Twin screw compressor

Abstract

The present application discloses a twin-screw compressor, which comprises: a shell having an inner cavity, and an air inlet and an air outlet connected to the inner cavity; at least one pair of screws, which are rotatably arranged in the inner cavity of the shell; and a gas regulating mechanism, which comprises at least one bypass hole, which is arranged on the outer peripheral side of the shell and selectively connected or closed to the inner cavity. The regulating structure required by the present application is simple, low in cost, high in reliability, and can realize continuous regulation of the suction volume, and can achieve a good energy efficiency ratio in various working conditions.

Description

Technical Field

[0001] The present application relates to the technical field of compressors, and in particular to a twin-screw compressor. Background Art

[0002] Compressor capacity regulation is related to whether the compressor's output capacity matches the demand. This can not only avoid energy waste caused by the compressor running at high capacity for a long time, but also improve the energy efficiency ratio of the entire refrigeration system and achieve energy conservation and emission reduction.

[0003] At present, the capacity adjustment method of screw refrigeration compressors is mainly speed adjustment. Speed ​​adjustment only controls the speed of the screw rotor through a variable frequency motor to achieve compressor capacity adjustment. However, when the rotor speed is low, the efficiency of the compressor is also greatly reduced.

[0004] Therefore, how to design a capacity regulation method with a simple structure, low cost and high reliability has become a problem that needs to be solved in the field. Summary of the invention

[0005] In view of this, the present application proposes a twin-screw compressor, which comprises:

[0006] A housing having an inner cavity, and an air inlet and an air outlet communicating with the inner cavity;

[0007] at least one pair of screws rotatably disposed in the inner cavity of the housing; and

[0008] The gas regulating mechanism comprises at least one bypass hole, which is arranged on the outer peripheral side of the shell and is selectively connected or closed to the inner cavity.

[0009] Preferably, the inner cavity includes a region where suction ends and compression begins, and the bypass hole is arranged in the region.

[0010] Further preferably, the gas regulating mechanism further includes a regulating pipeline and a regulating valve arranged in the regulating pipeline, one end of the regulating pipeline is communicated with the bypass hole, and the regulating valve is used to control the opening of the bypass hole.

[0011] Further preferably, the other end of the regulating pipeline is communicated with the air intake port or the external pipeline of the twin-screw compressor.

[0012] Further preferably, the regulating valve is configured in plurality.

[0013] Further preferably, each regulating valve is arranged in parallel.

[0014] Further preferably, the regulating valve includes an electric valve and / or a solenoid valve.

[0015] Further preferably, the electric valve and the solenoid valve are arranged in series.

[0016] Further preferably, the screw comprises: a primary screw rotor and a secondary screw rotor;

[0017] The bypass hole is arranged above the first-stage screw rotor.

[0018] Preferably, the twin-screw compressor further comprises a speed regulating mechanism for adjusting the speed of the screw.

[0019] The twin-screw compressor provided in the present application is provided with a bypass hole on the outer peripheral side of the compressor housing, which is selectively connected or closed to the inner cavity of the compressor, and is used to adjust the suction flow of the compressor, thereby adjusting the capacity of the compressor. This adjustment method can adapt to various working conditions of the compressor, and has a simple structure, and is economical and practical.

[0020] Other features and advantages of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings constituting a part of the present application are used to provide a further understanding of the present application, and the schematic implementation modes and descriptions of the present application are used to explain the present application. In the accompanying drawings:

[0022] Figure 1 This is a schematic side view of the structure of a twin-screw compressor according to a preferred embodiment of the present application;

[0023] Figure 2 This is a schematic diagram of the internal structure of a twin-screw compressor according to a preferred embodiment of the present application;

[0024] Figure 3 This is a schematic diagram of the bypass port position of a preferred embodiment of the present application;

[0025] Figure 4 This is a schematic structural diagram of a first gas regulating mechanism in a preferred embodiment of the present application;

[0026] Figure 5 This is a schematic structural diagram of the second gas regulating mechanism of the preferred embodiment of the present application.

[0027] Figure numbers: 1-housing; 2-a pair of screws; 21-a pair of primary screws; 22-a pair of secondary screws; 31-bypass hole; 32-regulating valve; 33-regulating pipeline. DETAILED DESCRIPTION

[0028] The technical solution of the present application will be described in detail below with reference to the accompanying drawings and in combination with the implementation modes.

[0029] A twin-screw compressor is a positive displacement gas compression machine whose working volume performs rotary motion. Its working cycle can be divided into three processes: suction, compression and exhaust. As the rotor (screw) rotates, each pair of meshing teeth successively completes the same working cycle.

[0030] Based on this, the present application provides a twin-screw compressor, combined with Figure 1-5 As shown, the twin-screw compressor includes: a shell 1, at least one pair of screws 2 and a gas regulating structure 3. The shell 1 has an inner cavity, and an air inlet and an air outlet communicated with the inner cavity, and at least one pair of screws 2 are rotatably arranged in the inner cavity of the shell 1. The gas enters the inner cavity from the air inlet, and the at least one pair of screws 2 in the inner cavity compresses the gas and then discharges it from the exhaust port. The gas regulating mechanism includes at least one bypass hole 31, which is arranged on the outer peripheral side of the shell 1 and selectively connected or closed with the inner cavity. The inner cavity is connected or closed by the at least one bypass hole 31 to adjust the capacity of the compressor.

[0031] Specifically, according to the above-mentioned introduction to the principle of the twin-screw compressor, the inner cavity of the compressor includes the area where the suction ends and the compression begins, that is, the position area where the suction of the screw 2 ends and the compression begins. Figure 3 Specifically, the coverage area is depicted with "dots". Specifically, it can be understood that when the female and male screws (a pair of screws) rotate in opposite directions, the volume between the teeth gradually increases, connects with the suction orifice, and starts to inhale. When the volume between the teeth reaches the maximum value, the suction orifice is disconnected, and the suction process ends. As the female and male screws continue to rotate, the volume between the teeth no longer increases, but begins to gradually decrease. At this time, the gas in the tooth grooves enclosed by the inner cavity, the suction end, and the exhaust end begins to be compressed, and the pressure gradually increases. Therefore, in a twin-screw compressor, the area where the suction ends and the compression begins is the position area where the volume between the teeth of screw 2 reaches the maximum value and then begins to decrease, that is, the part of the area where the suction orifice is disconnected, the tooth grooves begin to be closed, and the gas is compressed.

[0032] The bypass hole 31 in the present application is arranged in the above-mentioned area. In this area, the gas pressure in the compression chamber is greater than the suction pressure. Any opening at any position in this area can achieve the adjustment of the suction flow rate, such as Figure 3 Furthermore, since the bypass hole 31 is arranged in the region of the initial stage of gas compression, the method of adjusting the compressor working mode by using the bypass hole 31 in this region is more energy-efficient than the hot gas bypass method.

[0033] In a specific embodiment, the estimation method of compressor suction volume = compressor exhaust volume × compressor efficiency can be used to estimate that the adjustable compressor suction flow range in this area is 50%-100% of the maximum suction flow under full load conditions. Among them, the exhaust volume is the rated exhaust volume given by the compressor; the compressor efficiency is the product of the operating efficiencies of each component, usually between 0.75 and 0.85.

[0034] More specifically, the gas regulating mechanism also includes a regulating pipeline 33 and a regulating valve 32 disposed in the regulating pipeline 33. One end of the regulating pipeline 33 is in communication with the bypass hole 31, and the other end is directly in communication with the suction port of the twin-screw compressor, so as to connect the bypass hole 31 and the suction port to regulate the suction flow; or, one end of the regulating pipeline 33 is in communication with the bypass hole 31, and the other end is in communication with an external pipeline, and the external pipeline is used to regulate the suction flow of the area connected to the bypass hole 31. The regulating valve 32 controls the opening of the bypass hole 31 in the regulating pipeline 33 to regulate the suction flow of the compressor, thereby regulating the capacity of the compressor.

[0035] In addition, the regulating valve 32 can be configured as multiple regulating valves 32, each of which is arranged in parallel, so that graded regulation can be achieved through multiple regulating valves 32. The regulating valve 32 includes an electric valve and / or a solenoid valve. When the electric valve and the solenoid valve are set at the same time, they are arranged in series, and continuous regulation is achieved through the cooperation between the two. Figure 4-5 In the example, "S" indicates a solenoid valve, "M" indicates an electric valve, "S1" indicates one solenoid valve, and "S2" indicates another solenoid valve.

[0036] It can be understood that, according to the above description, if there are multiple regulating valves 32, these regulating valves 32 can all be electric valves, or all be solenoid valves, or both electric valves and solenoid valves. If the multiple regulating valves 32 include both electric valves and solenoid valves, then one electric valve and one solenoid valve can be connected in series to form a group of regulating valves 32, and each group of regulating valves 32 can be arranged in parallel. Of course, Figure 4-5 These are just examples of the two ways of setting the solenoid valve and the electric valve, and the present application is not limited thereto.

[0037] In addition, the twin-screw compressor in the present application can be a single-stage screw compressor or a two-stage screw compressor. If the compressor is a two-stage screw compressor, the screw 2 includes a pair of primary screws 21 and a pair of secondary screws 22, the inner cavity includes the cavity of the primary screw 21 and the cavity of the secondary screw 22, the air intake of the compressor is connected to the cavity of the primary screw 21, and the bypass 31 is arranged above the primary screw 21 and is located in the area where the primary screw 21 ends suction and starts compression.

[0038] In addition, the twin-screw compressor in the present application also includes a speed regulating mechanism (not shown in the figure) and / or an internal volume ratio regulating mechanism (not shown in the figure), the speed regulating mechanism is used to adjust the speed of the screw 2, and the internal volume ratio regulating mechanism is used to adjust the exhaust volume of the inner cavity by changing the flow area between the inner cavity and the exhaust port, thereby adjusting the internal volume ratio of the compressor. If the adjustment range of the existing regulating valve 32 is not sufficient to meet the operating requirements, the regulating valve 32 can be made to cooperate with the speed regulating mechanism and / or the internal volume ratio regulating mechanism to achieve a more comprehensive adjustment of the compressor working mode.

[0039] In addition, the twin-screw compressor in the present application may also include: gears (not shown in the figure), suction ports and exhaust ports. Among them, the gears are used to drive the screw 2 to rotate. The suction port is arranged on the suction end seat in the compressor, and can be specifically arranged in the upper area of ​​the shell 1. The exhaust port includes a side exhaust port and a bottom exhaust port, and both exhaust ports are arranged in the lower area of ​​the shell 1, one is arranged on the side of the lower area of ​​the shell 1, and the other is arranged on the bottom surface of the shell 1, so as to facilitate different pipe connection methods of the unit.

[0040] The twin-screw compressor provided in the present application is provided with a bypass hole on the outer peripheral side of the compressor housing, which is selectively connected or closed to the inner cavity of the compressor, and is used to adjust the suction flow of the compressor, thereby adjusting the capacity of the compressor. This adjustment method can adapt to various working conditions of the compressor, and has a simple structure, and is economical and practical.

[0041] Based on the structure of the twin-screw compressor of the present application, when the compressor is working, the working state of the compressor can be monitored, and the working state of the regulating valve 32 can be automatically or manually adjusted at any time according to the working state of the compressor to adapt to various working conditions of the compressor. The present application can at least realize the embodiments in the following working conditions:

[0042] Embodiment 1:

[0043] When the compressor is started, the opening of the regulating valve 32 is increased to increase the opening of the bypass hole 31, thereby reducing the suction flow of the compressor to reduce the compressor startup load as much as possible.

[0044] Embodiment 2:

[0045] When the compressor is in a high temperature condition, the opening of the regulating valve 32 is also increased to increase the opening of the bypass hole 31, thereby reducing the suction flow of the compressor. Under high temperature conditions, the power of the motor will increase significantly, and the actual matching motor power is considered according to the low temperature condition, so the suction volume needs to be reduced under high temperature conditions, otherwise the motor will be overloaded. In addition, the volume ratio of the compressor under high temperature conditions is also very small, and the volume ratio is also reduced when the suction flow is reduced, thereby achieving the purpose of energy saving. The temperature of the high temperature condition can be set as needed. For example, the condition when the evaporation temperature is greater than -20°C is set as the high temperature condition of the compressor.

[0046] Embodiment 3:

[0047] When the compressor is in a wet compression state, the opening of the regulating valve 32 is adjusted to the maximum to maximize the opening of the bypass hole 31, and the speed regulating mechanism can be selectively used to reduce the speed of the screw 2, and / or the volume ratio of the compressor can be lowered by using the volume ratio regulating mechanism. The wet compression state means that during the compression process of the compressor, liquid refrigerant is mixed in the refrigerant gas. In the wet compression state, the liquid refrigerant will evaporate during the compression process, thereby reducing the exhaust temperature. The larger the suction flow rate, the greater the moisture content. Therefore, it is necessary to control the regulating valve 32 to reduce the suction flow rate. If the screw speed is reduced and the volume ratio of the compressor is reduced while reducing the suction flow rate, the compressor can be protected from damage to the maximum extent by simultaneously controlling the suction volume and the degree of over-compression of the compressor.

[0048] The preferred embodiments of the present application are described in detail above; however, the present application is not limited to the specific details in the above embodiments. Within the technical concept of the present application, a variety of simple modifications can be made to the technical solution of the present application, and these simple modifications all fall within the protection scope of the present application.

[0049] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this application will not further describe various possible combinations.

[0050] In addition, the various implementation modes of the present application may be arbitrarily combined, and as long as they do not violate the concept of the present application, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A twin-screw compressor, comprising: A housing (1), the housing (1) having an inner cavity, and an air inlet and an air outlet communicated with the inner cavity; At least one pair of screw rods (2), the at least one pair of screw rods (2) being rotatably disposed in the inner cavity of the housing (1); and A gas regulating mechanism comprises at least one bypass hole (31), which is arranged on the outer peripheral side of the shell (1) and is selectively connected to or closed with the inner cavity.

2. The compressor according to claim 1, characterized in that The inner cavity includes a region where suction ends and compression begins, and the bypass hole (31) is arranged in the region.

3. The compressor according to claim 2, characterized in that The gas regulating mechanism further comprises a regulating pipeline (33) and a regulating valve (32) arranged in the regulating pipeline (33); one end of the regulating pipeline (33) is in communication with the bypass hole (31), and the regulating valve (32) controls the opening of the bypass hole (31).

4. The compressor according to claim 3, characterized in that The other end of the regulating pipeline (33) is communicated with the air intake port of the twin-screw compressor or an external pipeline.

5. The compressor according to claim 3, characterized in that The regulating valve (32) is configured in plural numbers.

6. The compressor according to claim 5, characterized in that Each regulating valve (32) is arranged in parallel.

7. The compressor according to claim 3, characterized in that The regulating valve (32) comprises an electric valve and / or a solenoid valve.

8. The compressor according to claim 7, characterized in that The electric valve and the solenoid valve are arranged in series.

9. The compressor according to claim 1 or 2, characterized in that The twin-screw compressor comprises: a pair of primary screws (21) and a pair of secondary screws (22); The bypass hole (31) is arranged above the primary screw (21).

10. The compressor according to claim 1, characterized in that The twin-screw compressor also includes a speed regulating mechanism for regulating the speed of the screw.

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