Carbon dioxide auto-cascade screw refrigerating unit

Abstract

The application discloses a carbon dioxide self-recovery screw refrigerating unit, which comprises a screw compressor, a condenser and a gas-liquid separator in sequence, wherein the gas-liquid separator is internally provided with a temperature sensing assembly, and a fault confirmation assembly is installed on the outer wall of the gas-liquid separator. The first temperature sensing bag and the second temperature sensing bag are used for monitoring the temperature changes of the gas phase area and the liquid phase area of the gas-liquid separator respectively, the temperature signal is converted into the mechanical displacement of the diaphragm box through the capillary, and then the mechanical displacement is transmitted to the two ends of the lever through the push rod. When the temperatures detected by the two temperature sensing bags are different, the lever tilts to the side where the temperature decreases first, and the corresponding sensing part is triggered. The whole device does not need external energy, can realize the automatic identification and signal output of the gas phase liquid carrying and the liquid volume storage two faults, and provides reliable basic signals for subsequent differentiated control.

Description

Technical Field

[0001] This invention relates to the field of refrigeration units, and in particular to a carbon dioxide self-cascading screw refrigeration unit. Background Technology

[0002] Carbon dioxide cascade screw chillers are widely used in biomedicine, food freezing, and cryogenic preservation due to their environmental friendliness (GWP=1), safety, and ability to achieve ultra-low temperature refrigeration below -60℃. One of their core components—the gas-liquid separator—is prone to two typical malfunctions during operation.

[0003] Liquid carryover in the vapor phase: Liquid refrigerant is carried into the vapor phase outlet pipeline by the gas flow, which may cause liquid slugging damage to the compressor.

[0004] Liquid accumulation: High-boiling-point components accumulate excessively at the bottom, affecting the system's component balance and refrigeration efficiency.

[0005] To address the aforementioned issues, a search revealed Chinese patent CN202311473945.0, which discloses a dual-temperature-bulb self-regulating temperature control valve. This valve uses two temperature bulbs to detect temperatures at different locations and outputs a single signal through mechanical comparison to control the valve opening. While this solution achieves dual-point temperature detection, it cannot distinguish between unilateral temperature fluctuations and actual malfunctions, making it prone to misjudgment.

[0006] Chinese patent CN202311857270.X discloses a component control method for a self-cascade refrigeration system, which uses electronic sensors to detect exhaust pressure and inlet liquid temperature, and adjusts the opening of the electronic expansion valve through a controller algorithm. Although this scheme has high control accuracy, it relies on a power supply and electronic controller, is susceptible to electromagnetic interference, requires programming and debugging, and is costly.

[0007] In addition, although existing self-regulating temperature control valves achieve passive temperature control, they can only detect the temperature at a single point and cannot distinguish between two types of faults: gas phase liquid carryover and liquid accumulation.

[0008] Therefore, there is an urgent need for a purely mechanical solution that can distinguish between two types of faults, prevent misjudgment of unilateral disturbances, require no external energy, and enable differentiated control of multiple valves. Summary of the Invention

[0009] In view of this, the present invention addresses the deficiencies of the prior art, and its main objective is to provide a carbon dioxide self-cascading screw chiller unit that solves the aforementioned problems.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: a carbon dioxide self-cascading screw refrigeration unit, comprising a screw compressor, a condenser, and a gas-liquid separator connected in sequence, wherein a temperature sensing component is provided inside the gas-liquid separator, and a fault confirmation component is installed on the outer wall of the gas-liquid separator;

[0011] The gas-liquid separator includes a tank, a first pipe disposed on one side of the tank and connected to a screw compressor, and a gas phase outlet and a liquid phase outlet disposed at the top and bottom of the tank, respectively.

[0012] The temperature sensing component includes a first temperature sensing bulb, a second temperature sensing bulb, a capillary tube, and a membrane box. The first temperature sensing bulb is installed inside the gas phase outlet, and the second temperature sensing bulb is installed above the liquid phase outlet. The first temperature sensing bulb and the second temperature sensing bulb are respectively connected to the corresponding membrane box through the capillary tube.

[0013] The fault confirmation component includes a lever, two push rods, and two sensors. The two push rods are respectively located at both ends of the lever, with one end of each push rod connected to a corresponding diaphragm, and the other end of each push rod arranged opposite to the corresponding sensor.

[0014] Furthermore, the first temperature sensing bulb, the capillary tube connected to the first temperature sensing bulb, and the corresponding membrane box are all filled with propylene, and the capillary tube is connected to the membrane box.

[0015] Furthermore, the second temperature sensing bulb, the capillary tube connected to the second temperature sensing bulb, and the corresponding membrane box are all filled with low-temperature silicone oil, and the capillary tube is connected to the membrane box.

[0016] Furthermore, the outer wall of the capillary is fitted with an insulation layer.

[0017] Furthermore, the lever component includes a shaft, a torsion spring, and a plate. Both the torsion spring and the plate are sleeved on the shaft, with one end of the torsion spring connected to the shaft and the other end of the torsion spring connected to the plate.

[0018] Furthermore, both ends of the plate are provided with openings, through which the push rod passes, and a locking device is provided between the opening and the push rod.

[0019] Furthermore, the locking component includes a slot formed on two opposite sidewalls of the opening, a locking strip on the inner wall of the slot, and an elastic locking plate on the outer wall of the push rod, with the elastic locking plate corresponding to the locking strip.

[0020] Furthermore, the push rod includes a first rod body and a second rod body, the diameter of the second rod body is smaller than the diameter of the first rod body, and the first rod body is connected to the corresponding diaphragm box.

[0021] Furthermore, the elastic plate includes a spring and a base plate. A receiving groove is provided on the outer wall of the first rod. The spring is located in the receiving groove. One end of the base plate is inserted into the receiving groove and connected to the spring. The opposite surfaces of the base plate and the plate are provided with mutually compatible inclined surfaces.

[0022] Furthermore, the self-cascading screw chiller unit also includes a first refrigeration branch connected to the gas phase outlet of the gas-liquid separator and a second refrigeration branch connected to the liquid outlet of the gas-liquid separator; the first refrigeration branch and the second refrigeration branch exchange heat through heat exchange components to form a self-cascading cycle.

[0023] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, as can be seen from the above technical solution, the first and second temperature sensing bulbs are used to monitor the temperature changes in the gas phase zone and liquid phase zone of the gas-liquid separator, respectively. The temperature signal is converted into the mechanical displacement of the membrane capsule through the capillary tube, and then transmitted to both ends of the lever by the push rod. When there is a temperature difference detected by the two temperature sensing bulbs, the lever tilts to the side with the lower temperature first, triggering the corresponding sensing element. The entire device does not require external energy and can realize the automatic identification and signal output of two faults: gas phase liquid carryover and liquid accumulation, providing a reliable basic signal for subsequent differentiated control.

[0024] To more clearly illustrate the structural features and effects of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0025] Figure 1 This is a perspective view of Embodiment 1 of the present invention.

[0026] Figure 2 This is a cross-sectional view of the gas-liquid separator of Embodiment 1 of the present invention.

[0027] Figure 3 This is Embodiment 1 of the present invention. Figure 2 The diagram at point A is shown.

[0028] Figure 4 This is a cross-sectional view of the lever component according to Embodiment 1 of the present invention.

[0029] Figure 5 This is Embodiment 1 of the present invention. Figure 2 The diagram at point B is shown.

[0030] Explanation of reference numerals in the attached diagram:

[0031] 10 screw compressors;

[0032] Condenser 20;

[0033] Gas-liquid separator 30, tank 31, first pipeline 32, gas phase outlet 33, liquid phase outlet 34;

[0034] Temperature sensing component 40, first temperature sensing bulb 41, second temperature sensing bulb 42, capillary tube 43, diaphragm box 44, insulation layer 45;

[0035] Fault confirmation component 50, lever 51, shaft 511, torsion spring 512, plate 513, through port 5131, locking component 514, slot 5141, locking strip 5142, elastic plate 5143, spring 51431, base plate 51432, push rod 52, first rod 521, receiving groove 5211, second rod 522, sensing component 53;

[0036] First refrigeration branch 60;

[0037] Second refrigeration branch 70;

[0038] Heat exchange component 80. Detailed Implementation

[0039] Please refer to Figure 1-5 As shown, it illustrates the specific structure of a preferred first embodiment of the present invention, which is a carbon dioxide self-cascading screw refrigeration unit, including a screw compressor 10, a condenser 20, and a gas-liquid separator 30 connected in sequence. The gas-liquid separator 30 is provided with a temperature sensing component 40 inside, and a fault confirmation component 50 is installed on the outer wall of the gas-liquid separator 30.

[0040] The gas-liquid separator 30 includes a tank 31, a first pipe 32 disposed on one side of the tank 31 and connected to the screw compressor 10, and a gas phase outlet 33 and a liquid phase outlet 34 disposed at the top and bottom of the tank 31, respectively.

[0041] The temperature sensing component 40 includes a first temperature sensing element 41, a second temperature sensing element 42, a capillary tube 43, and a membrane box 44. The first temperature sensing element 41 is installed inside the gas phase outlet 33, and the second temperature sensing element 42 is installed above the liquid phase outlet 34. The first temperature sensing element 41 and the second temperature sensing element 42 are respectively connected to the corresponding membrane box 44 through the capillary tube 43.

[0042] The fault confirmation component 50 includes a lever 51, two push rods 52, and two sensors 53. The two push rods 52 are respectively located at both ends of the lever 51. One end of each push rod 52 is connected to a corresponding diaphragm 44, and the other end is opposite to the corresponding sensor 53. When the gas phase contains liquid, the first temperature sensor 41 responds first; when liquid is present, the second temperature sensor 42 responds first. The two temperature sensors are independently arranged and do not interfere with each other, providing a physical basis for distinguishing between the two types of faults, and the entire detection process requires no external power supply. When a temperature sensor detects a temperature change, its internal medium contracts, transmitting the pressure change to the diaphragm 44 through the capillary tube 43, driving the diaphragm 44 to produce mechanical displacement. When the temperature detected by one temperature sensor differs from that of the other, the diaphragm 44 corresponding to that temperature sensor displaces, and the push rod 52 connected to that diaphragm 44 applies a force to one end of the lever 51, causing the lever 51 to tilt. The tilt direction of lever 51 directly reflects the side where the temperature drops first, thus determining the fault type: tilting to the first side indicates liquid in the gas phase, and tilting to the second side indicates liquid accumulation.

[0043] When lever 51 tilts, it comes into contact with the corresponding sensor 53. The sensor 53 then sends an electrical signal to control other actuators in the self-cascading screw chiller unit to address the problem of liquid carryover in the gas phase or liquid accumulation. It should be noted that when lever 51 tilts to one side, it triggers the corresponding sensor 53 to output a control signal. The two sensors 53 can be connected to different actuators (such as a gas phase outlet proportional valve and a bottom drain valve) to achieve differentiated control: closing the proportional valve when liquid carryover occurs and opening the drain valve when liquid accumulation occurs.

[0044] For example, the first temperature sensing element 41, the capillary tube 43 connected to the first temperature sensing element 41, and the corresponding membrane box 44 are all filled with propylene, and the capillary tube 43 is connected to the membrane box 44. When the first temperature sensor 41 senses a temperature change within the gas phase outlet 33, the propylene medium inside expands or contracts in volume. This volume change is transmitted to the diaphragm 44 through the pressure within the capillary tube 43, driving the diaphragm 44 to produce a corresponding mechanical displacement. Since the boiling point of propylene is -47.6℃, within the typical operating temperature range (approximately -40℃ to -20℃) of the gas phase outlet 33 of the self-cascade refrigeration system, propylene exists in a gas-liquid two-phase coexistence state. When the temperature changes, propylene undergoes a gas-liquid phase transition, and its volume change is much greater than that of ordinary liquids due to thermal expansion and contraction. Therefore, the first temperature sensor 41 has extremely high sensitivity to temperature changes and can quickly respond to sudden temperature drops when a gas phase liquid-carrying fault occurs. At the same time, the entire closed system is isolated from the outside world, and the conversion from temperature signal to pressure signal and then to mechanical displacement can be completed without external energy, realizing purely mechanical and passive signal transmission, avoiding the signal drift or failure problems that may occur in electronic sensors in low-temperature environments.

[0045] For example, the second temperature sensing bulb 42, the capillary tube 43 connected to the second temperature sensing bulb 42, and the corresponding diaphragm box 44 are all filled with low-temperature silicone oil, and the capillary tube 43 is connected to the diaphragm box 44. When the second temperature sensing bulb 42 senses a temperature change in the liquid refrigerant above the liquid phase outlet 34, the low-temperature silicone oil medium inside it undergoes thermal expansion and contraction. The volume change is transmitted to the diaphragm box 44 through the pressure in the capillary tube 43, driving the diaphragm box 44 to produce a corresponding mechanical displacement. The freezing point of the low-temperature silicone oil is below -70°C, and it remains liquid in the typical operating temperature range (approximately -60°C to -30°C) of the liquid phase region at the bottom of the self-cascade refrigeration system, and will not solidify or fail due to low temperature. This ensures the normal operation of the second temperature sensing bulb 42 under extremely low temperature conditions. Unlike the gas-liquid phase change of propylene, the thermal expansion and contraction of the low-temperature silicone oil is continuous. The linear response to temperature changes is relatively smooth, which perfectly matches the slow temperature drop during liquid storage failures. This allows for stable detection of temperature changes in the liquid phase region, avoiding misjudgments caused by temperature fluctuations. Furthermore, the entire closed system is isolated from the outside world, enabling the conversion of temperature signals to pressure signals and then to mechanical displacement without external energy, achieving purely mechanical and passive signal transmission. In addition, the low-temperature silicone oil has good chemical stability, does not react with refrigerants commonly used in self-cascade refrigeration systems, and will not deteriorate with long-term use, ensuring the service life and detection reliability of the second temperature sensor 42.

[0046] For example, the outer wall of the capillary 43 is fitted with a heat insulation layer 45. The heat insulation layer 45 isolates the capillary 43 from the external environment, keeping the temperature of the medium inside the capillary 43 basically stable. This ensures that the temperature changes detected by the temperature sensor can be transmitted to the diaphragm box accurately and reliably through the capillary 43, avoiding interference from ambient temperature fluctuations on signal transmission. At the same time, in the self-cascade refrigeration system, there may be local low-temperature or high-temperature areas around the gas-liquid separator 30. The heat insulation layer 45 can effectively counteract the influence of these environmental factors on the pressure signal, improving the detection reliability and anti-environmental interference capability of the fault confirmation component 50.

[0047] It should be noted that the insulation layer 45 can be made of commonly used insulation materials such as rubber and plastic sponge and glass wool, which are inexpensive and easy to install, and will not significantly increase the manufacturing cost and installation difficulty of the unit.

[0048] For example, the lever 51 includes a shaft 511, a torsion spring 512 and a plate 513. The torsion spring 512 and the plate 513 are both sleeved on the shaft 511, and one end of the torsion spring 512 is connected to the shaft 511, while the other end of the torsion spring 512 is connected to the plate 513. The shaft 511 is fixedly mounted on the outer wall of the gas-liquid separator 30, serving as the rotation center of the lever 51. The torsion spring 512 and the plate 513 are both sleeved on the shaft 511. One end of the torsion spring 512 is fixedly connected to the shaft 511, and the other end is fixedly connected to the plate 513. The two ends of the plate 513 are respectively arranged opposite to the two push rods 52. When any push rod 52 applies a thrust to one end of the plate 513, the plate 513 overcomes the elastic force of the torsion spring 512 and deflects around the shaft 511. The direction of deflection indicates the corresponding fault type. When the thrust disappears, the restoring force of the torsion spring 512 drives the plate 513 back to the initial equilibrium position. Through the above structure, the lever 51 can convert the displacement signals of the two diaphragm boxes 44 into a single directional deflection output, and also has an automatic reset capability without manual intervention.

[0049] For example, both ends of the plate 513 have openings 5131, through which the push rod 52 passes, and a locking element 514 is provided between the opening 5131 and the push rod 52. For ease of explanation of the working principle, the push rod 52 is divided into a first push rod 52a and a second push rod 52b. When the first push rod 52a retracts due to a temperature drop detected by the corresponding temperature sensor, it locks itself against the plate 513 via the locking element 514. At this time, the plate 513 tilts under the influence of the first push rod 52a. During this process, the side of the plate 513 that contacts the second push rod 52b can tilt upwards thanks to the opening 5131, thereby avoiding interference with the second push rod 52b and ensuring smooth deflection of the plate 513.

[0050] For example, the locking member 514 includes a slot 5141 formed on two opposite sidewalls of the opening 5131, a locking strip 5142 provided on the inner wall of the slot 5141, and an elastic locking plate 5143 provided on the outer wall of the push rod 52, wherein the elastic locking plate 5143 corresponds to the locking strip 5142. When the first push rod 52a retracts due to the temperature decrease detected by the corresponding temperature sensor, the elastic plate 5143 on the first push rod 52a extends into the corresponding slot 5141 and overlaps with the locking strip 5142 in the slot 5141, thereby fixing the first push rod 52a relative to the plate 513, which in turn causes the plate 513 to tilt. During the tilting process of the plate 513, the second push rod 52b moves in the opposite direction relative to the plate 513. At this time, the distance between the elastic plate 5143 on the second push rod 52b and the inner wall of the corresponding opening 5131 gradually decreases, and the elastic plate 5143 is squeezed inward by the inner wall of the opening 5131. In this state, the locking strip 5142 cannot overlap with the elastic locking plate 5143, and the plate 513 can continue to tilt past the elastic locking plate 5143 on the second push rod 52b until the end of the opening 5131 abuts against the outer wall of the second push rod 52b, at which point a locking state is formed. This locking state can only be released when the second push rod 52b moves itself, so that the plate 513 can continue to tilt until it contacts the corresponding sensing element 53, thereby determining whether there is a real gas phase with liquid or liquid accumulation.

[0051] For example, the push rod 52 includes a first rod body 521 and a second rod body 522. The diameter of the second rod body 522 is smaller than the diameter of the first rod body 521. The first rod body 521 is connected to the corresponding diaphragm box 44. Based on the previous paragraph, the plate 513 corresponding to the second push rod 52b, due to its tilt, forms an abutment between its inner opening 5131 and the inner wall of the larger-diameter first rod body 521, preventing the plate 513 from tilting further and thus forming a stable locked state. When the second push rod 52b retracts, causing the second rod body 522 to move to the position of the opening 5131, a new gap is formed between the inner wall of the opening 5131 and the second rod body 522, allowing the plate 513 to continue tilting.

[0052] For example, the elastic plate 5143 includes a spring 51431 and a base plate 51432. The outer wall of the first rod 521 is provided with a receiving groove 5211. The spring 51431 is disposed in the receiving groove 5211. One end of the base plate 51432 is inserted into the receiving groove 5211 and connected to the spring 51431. The opposite surfaces of the base plate 51432 and the plate 5142 are provided with mutually adapted inclined surfaces. When the push rod 52 slides to the set position, the base plate 51432 extends out of the receiving groove 5211 under the push of the spring 51431 and inserts into the slot 5141. At this time, the base plate 51432 and the card strip 5142 are stacked one on top of the other, and their inclined surfaces do not contact each other. The end face of the base plate 51432 abuts against the side of the card strip 5142, thereby achieving relative fixation between the push rod 52 and the plate 513. When the plate 513 tilts, the inner wall of the through 5131 squeezes the base plate 51432, causing it to overcome the elastic force of the spring 51431 and retract into the receiving groove 5211. Under this compressed and contracted state, the relative position between the base plate 51432 and the card strip 5142 changes, and their inclined surfaces contact each other and slide relative to each other. Due to the guiding effect of the inclined surfaces, the card strip 5142 can smoothly pass over the base plate 51432, thereby releasing the locking state and allowing the plate 513 to continue to tilt.

[0053] For example, the self-cascading screw chiller unit also includes a first refrigeration branch 60 connected to the gas phase outlet 33 of the gas-liquid separator 30 and a second refrigeration branch 70 connected to the liquid outlet 34 of the gas-liquid separator 30. The first refrigeration branch 60 and the second refrigeration branch 70 exchange heat through a heat exchange component 80, forming a self-cascading cycle. The gas-liquid separator 30 separates the condensed mixed working fluid into gaseous and liquid phases. The gaseous working fluid (rich in low-boiling-point components) from the gas phase outlet 33 enters the first refrigeration branch 60, and the liquid working fluid (rich in high-boiling-point components) from the liquid phase outlet 34 enters the second refrigeration branch 70. The two working fluids exchange heat in the heat exchange component 80. The liquid working fluid (high-boiling-point components) in the second refrigeration branch 70 evaporates and absorbs heat, cooling the gaseous working fluid (low-boiling-point components) in the first refrigeration branch 60, further cooling the working fluid in the first refrigeration branch 60 or even partially condensing it, thereby obtaining a lower evaporation temperature.

[0054] In summary, the key design focus of this invention is;

[0055] In the initial state, both the first temperature sensor 41 and the second temperature sensor 42 are at normal temperature, both diaphragm boxes 44 are in their initial positions, and both push rods 52 are in the extended state, with the end of the second rod 522 located below the corresponding end of the plate 513 and in contact with the plate 513. The plate 513 remains horizontal under the action of the torsion spring 512, and neither of the two sensors 53 is triggered.

[0056] When a liquid-carrying failure occurs in the gas phase, the temperature inside the gas phase outlet 33 decreases first. The propylene inside the first temperature sensing bulb 41 contracts, and the membrane box 44 connected to it contracts accordingly, causing the first push rod 52a to move in the retraction direction. When the first push rod 52a retracts, its second rod 522 leaves the corresponding end of the plate 513, and the plate 513 loses support at that end. At the same time, the elastic retaining plate 5143 on the first push rod 52a moves with the first push rod 52a and extends into the corresponding retaining groove 5141. The end of the elastic retaining plate 5143 overlaps with the retaining strip 5142, so that the first push rod 52a and the plate 513 are relatively fixed.

[0057] At this time, the second push rod 52b is still in the extended state, and the end of its second rod body 522 remains in contact with the corresponding end of the plate body 513. After the first push rod 52a retracts, the plate body 513 loses the support at that end and tilts towards the first push rod 52a under its own weight and the action of the torsion spring 512. That end of the plate body 513 moves downward, and the other end tilts upward. When the plate body 513 tilts, its tilted end moves upward, causing the opening 5131 to move upward relative to the second push rod 52b. The elastic retaining plate 5143 on the second push rod 52b is squeezed by the inner wall of the opening 5131 and retracts into the receiving groove 5211. The retaining strip 5142 cannot overlap with the elastic retaining plate 5143, and the plate body 513 can continue to tilt past the elastic retaining plate 5143 on the second push rod 52b.

[0058] The plate 513 continues to tilt until the end of the opening 5131 abuts against the outer wall of the first rod 521 of the second push rod 52b. At this point, the plate 513 is stopped by the first rod 521 of the second push rod 52b, forming a locked state. The plate 513 cannot tilt further, so the corresponding sensor 53 will not be triggered. When the second push rod 52b subsequently retracts, the second rod 522 moves to the position of the opening 5131, and a gap is restored between the inner wall of the opening 5131 and the second rod 522. The plate 513 loses its last support and can continue to tilt until the corresponding sensor 53 is triggered, outputting the first control signal. The first control signal is used to control the proportional valve on the gas phase outlet 33 pipeline to close less, reducing the gas phase outlet flow rate.

[0059] When a liquid accumulation failure occurs, the temperature above the liquid outlet 34 first decreases. The low-temperature silicone oil inside the second temperature sensor 42 contracts, and the membrane box 44 connected to it contracts accordingly, causing the second push rod 52b to move in the retraction direction. Symmetrically, the second push rod 52b is locked, the plate 513 tilts towards the second push rod 52b, and when the first push rod 52a subsequently retracts, it triggers another sensor 53, outputting a second control signal. The second control signal is used to control the opening of the drain valve on the liquid outlet 34 pipeline to drain the accumulated liquid.

[0060] When both temperature sensors detect a temperature change at the same time, both push rods 52 retract simultaneously, and both ends of the plate 513 lose support at the same time. The plate 513 remains horizontal under the action of the torsion spring 512, and neither of the two sensors 53 is triggered, thus avoiding misjudgment due to changes in system operating conditions.

[0061] The self-cascading screw chiller unit also includes a first refrigeration branch 60 connected to the gas phase outlet 33 of the gas-liquid separator 30, and a second refrigeration branch 70 connected to the liquid outlet 34 of the gas-liquid separator 30. The first refrigeration branch 60 and the second refrigeration branch 70 exchange heat through a heat exchange component 80 to form a self-cascading cycle;

[0062] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A carbon dioxide auto-cascade screw refrigeration unit, comprising a screw compressor (10), a condenser (20), a gas-liquid separator (30) connected in sequence, characterized in that: The gas-liquid separator (30) is equipped with a temperature sensing component (40) inside and a fault confirmation component (50) is installed on the outer wall of the gas-liquid separator (30). The gas-liquid separator (30) includes a tank (31), a first pipe (32) disposed on one side of the tank (31) and connected to the screw compressor (10), and a gas phase outlet (33) and a liquid phase outlet (34) respectively disposed at the top and bottom of the tank (31). The temperature sensing component (40) includes a first temperature sensing element (41), a second temperature sensing element (42), a capillary tube (43), and a membrane box (44). The first temperature sensing element (41) is installed inside the gas phase outlet (33), and the second temperature sensing element (42) is installed above the liquid phase outlet (34). The first temperature sensing element (41) and the second temperature sensing element (42) are respectively connected to the corresponding membrane box (44) through the capillary tube (43). The fault confirmation component (50) includes a lever (51), two push rods (52) and two sensors (53). The two push rods (52) are respectively disposed at both ends of the lever (51). One end of each push rod (52) is connected to the corresponding diaphragm (44), and the other end of each push rod (52) is arranged opposite to the corresponding sensor (53).

2. A carbon dioxide auto-cascade screw chiller unit according to claim 1, characterised in that: The first temperature sensing bulb (41), the capillary tube (43) connected to the first temperature sensing bulb (41) and the corresponding membrane box (44) are all filled with propylene, and the capillary tube (43) is connected to the membrane box (44).

3. A carbon dioxide auto-cascade screw chiller unit according to claim 1, characterised in that: The second temperature sensing bulb (42), the capillary tube (43) connected to the second temperature sensing bulb (42) and the corresponding membrane box (44) are all filled with low-temperature silicone oil, and the capillary tube (43) is connected to the membrane box (44).

4. A carbon dioxide self-cascading screw chiller unit according to any one of claims 1-3, characterized in that: The outer wall of the capillary (43) is fitted with a heat insulation layer (45).

5. A carbon dioxide self-cascading screw chiller unit according to claim 1, characterized in that: The lever (51) includes a shaft (511), a torsion spring (512) and a plate (513). The torsion spring (512) and the plate (513) are both sleeved on the shaft (511), and one end of the torsion spring (512) is connected to the shaft (511), while the other end of the torsion spring (512) is connected to the plate (513).

6. A carbon dioxide self-cascading screw chiller unit according to claim 5, characterized in that: Both ends of the plate (513) are provided with openings (5131), the push rod (52) passes through the openings (5131), and a locking member (514) is provided between the openings (5131) and the push rod (52).

7. A carbon dioxide self-cascading screw chiller unit according to claim 6, characterized in that: The locking member (514) includes a slot (5141) formed on two opposite side walls of the opening (5131), a locking strip (5142) provided on the inner wall of the slot (5141), and an elastic locking plate (5143) provided on the outer wall of the push rod (52). The elastic locking plate (5143) is positioned corresponding to the locking strip (5142).

8. A carbon dioxide self-cascading screw chiller unit according to claim 7, characterized in that: The push rod (52) includes a first rod body (521) and a second rod body (522), the diameter of the second rod body (522) is smaller than the diameter of the first rod body (521), and the first rod body (521) is connected to the corresponding diaphragm box (44).

9. A carbon dioxide self-cascading screw chiller unit according to claim 8, characterized in that: The elastic plate (5143) includes a spring (51431) and a base plate (51432). The outer wall of the first rod (521) is provided with a receiving groove (5211). The spring (51431) is disposed in the receiving groove (5211). One end of the base plate (51432) is inserted into the receiving groove (5211) and connected to the spring (51431). The opposite surfaces of the base plate (51432) and the plate (5142) are provided with mutually compatible inclined surfaces.

10. A carbon dioxide self-cascading screw chiller unit according to claim 1, characterized in that: The self-cascading screw chiller unit also includes a first refrigeration branch (60) connected to the gas phase outlet (33) of the gas-liquid separator (30) and a second refrigeration branch (70) connected to the drain port (34) of the gas-liquid separator (30); the first refrigeration branch (60) and the second refrigeration branch (70) exchange heat through a heat exchange component (80) to form a self-cascading cycle.

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