Screw compressor and air flow adjusting method

Abstract

The invention discloses a screw compressor and an air flow adjusting method, and belongs to the technical field of compressors, and the screw compressor comprises an air cylinder shell provided with a first liquid injection opening and a second liquid injection opening; the check block assembly is arranged in the air cylinder shell and connected with the air cylinder shell. High-pressure liquid is injected into the first liquid injection opening, so that the high-pressure liquid enters the containing cavity through the first overflowing hole and the second overflowing hole, and therefore the sliding valve assembly is pushed to move in the length direction, and the compression cavity communicates with the exhaust channel; part of gas in the compression cavity can be exhausted through the exhaust channel, and therefore the purpose of adjusting the gas amount in the compression cavity is achieved. According to the structure, high-pressure liquid directly acts on the sliding valve assembly, the sliding valve assembly is pushed through the high-pressure liquid, and therefore the sliding valve assembly can conveniently move in the length direction, the sliding difficulty of the sliding valve assembly is reduced, and the air amount in the compression cavity can be rapidly adjusted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of compressors, in particular to a screw compressor and a gas volume adjusting method. BACKGROUND

[0002] An oil-free screw compressor is a kind of gas compressor without using lubricating oil in the compression process, which has the characteristics of pure compressed gas, high efficiency and energy saving, and is widely used in fields with high requirements for gas quality. The oil-free screw compressor mainly consists of a pair of intermeshing male and female rotors. When the rotors rotate, air enters the compressor from the suction port. With the rotation of the rotors, the volume between the teeth gradually decreases, the air is compressed, the pressure is increased, and finally discharged from the exhaust port. In some working conditions, it may be necessary to deliver different exhaust volumes from the exhaust port, but the compressor is not convenient for adjusting the volume of the compressed gas, which is not conducive to the use of the compressor. SUMMARY

[0003] The embodiments of the present application provide a screw compressor and a gas volume adjusting method to solve the technical problem that the compressor is not convenient for adjusting the volume of the compressed gas.

[0004] In order to achieve the above-mentioned purpose, according to the first aspect of the present application, a screw compressor is provided, comprising: a cylinder housing having a first liquid injection port and a second liquid injection port; a stop block assembly arranged in the cylinder housing and connected with the cylinder housing, the stop block assembly having a first flow hole and an exhaust passage, the first flow hole being in communication with the first liquid injection port, and the exhaust passage being in communication with an air inlet passage of the screw compressor; a piston assembly arranged in the cylinder housing, the piston assembly comprising a connecting rod part and a head part, the connecting rod part being connected to the stop block assembly and having a second flow hole in communication with the first flow hole, and the connecting rod part being arranged in and connected with the head part; a spool valve assembly arranged in the cylinder housing and in sliding connection with the cylinder housing, the spool valve assembly and the cylinder housing enclosing a compression chamber and a liquid storage chamber, the liquid storage chamber being in communication with the second liquid injection port, the spool valve assembly having a containing cavity, the head part being arranged in the containing cavity and in sealing connection with the inner wall of the containing cavity, and the second flow hole being in communication with the containing cavity; wherein the piston assembly is configured to deliver high-pressure liquid into the containing cavity through the second flow hole, push the spool valve assembly to move along the length direction and separate from the stop block assembly, so as to make the compression chamber in communication with the exhaust passage.

[0005] Optionally, the stopper assembly has a fixing groove, and the connecting rod part is embedded into the fixing groove and connected with the stopper assembly. The connecting rod part has a positioning groove, and the stopper assembly includes a positioning block arranged on the inner wall of the fixing groove and embedded into the positioning groove.

[0006] Optionally, the cylinder shell has a mounting groove, and the stopper assembly further includes a mounting part embedded into the mounting groove and detachably connected with the cylinder shell.

[0007] Optionally, the connecting rod part has a circumferentially arranged annular groove in communication with the second flow hole, and the annular groove is in communication with the first flow hole.

[0008] Optionally, the connecting rod part has a plurality of circumferentially arranged first sealing grooves arranged on both sides of the annular groove along the length direction. The piston assembly includes a plurality of first sealing parts each arranged in one of the first sealing grooves, and the connecting rod part is sealingly connected with the stopper assembly through the first sealing parts.

[0009] Optionally, the end head part has a plurality of circumferentially arranged second sealing grooves, and the piston assembly further includes a plurality of second sealing parts each arranged in one of the second sealing grooves, and the end head part is sealingly connected with the inner wall of the accommodating cavity through the second sealing parts.

[0010] Optionally, the piston assembly further includes: a resilient part arranged on the side of the end head part facing the stopper assembly and sleeved on the connecting rod part, and the two ends of the resilient part abut against the end head part and the inner wall of the accommodating cavity, respectively.

[0011] Optionally, the liquid storage cavity has a first side wall and a second side wall arranged at intervals along the length direction, and the spool valve assembly includes: a body slidingly connected with the cylinder shell; a spacing part arranged in the liquid storage cavity and connected with the first side wall, the spacing part being used for spacing the first side wall and the second side wall; along the length direction, the second side wall and the second liquid injection port have a maximum distance L1, and along the length direction, the spacing part has a size L2, and L2≥L1 is satisfied.

[0012] Optionally, the cylinder housing has two dovetail grooves arranged along a width direction and extending along the length direction, and the slide valve assembly includes two matching parts arranged along the width direction and embedded in the two dovetail grooves respectively. The dovetail groove has a first contact surface and a second contact surface connected to each other, and the matching part has a first matching surface and a second matching surface connected to each other, the first matching surface being connected to the first contact surface, and the second matching surface being connected to the second contact surface.

[0013] Optionally, the stop block assembly includes two connecting parts arranged along the width direction and embedded in the two dovetail grooves respectively. The connecting part includes a first connecting surface and a second connecting surface connected to each other, the first connecting surface being connected to the first contact surface, and the second connecting surface being connected to the second contact surface.

[0014] Optionally, an included angle α between the first contact surface and the second contact surface satisfies 55°≤α≤70°.

[0015] Optionally, an inner wall of the dovetail groove and a surface of the matching part are provided with a coating structure for reducing friction when the matching part slides in the dovetail groove.

[0016] Optionally, the stop block assembly has a blowdown port for discharging liquid between the stop block assembly and the slide valve assembly.

[0017] Optionally, a distance between the slide valve assembly and the stop block assembly along the length direction is H1, and the screw compressor further includes a rotor assembly, and a size of the rotor assembly along the length direction in the compression cavity is H2, satisfying 0≤H1 / H2≤0.4.

[0018] According to a second aspect of the present application, a gas volume adjusting method of a screw compressor is provided, which is applied to the screw compressor according to any one of the above-mentioned embodiments, and the method includes: When reducing the exhaust volume of the screw compressor, high-pressure liquid is delivered from a first liquid injection port of the cylinder housing to a first flow hole of the stop block assembly, so that the high-pressure liquid enters a containing cavity of the slide valve assembly through a second flow hole; The high-pressure liquid pushes the slide valve assembly to move along the length direction away from the stop block assembly, so that the compression cavity is communicated with an exhaust passage, and the compressed gas in the compression cavity flows back to an intake passage of the screw compressor through the exhaust passage.

[0019] Optionally, the method further includes: When the discharge capacity of the screw compressor is increased, the high-pressure liquid is stopped from being delivered to the second through hole, and the high-pressure liquid is injected into the liquid storage cavity through the second liquid injection port of the cylinder shell; Under the thrust of the high-pressure liquid, the slide valve assembly moves along the length direction to the direction close to the stopper assembly, gradually closes the communication between the compression cavity and the exhaust passage, until the slide valve assembly is attached to the stopper assembly, and the discharge capacity of the screw compressor reaches the maximum.

[0020] The screw compressor of the embodiment of the present application comprises: a cylinder shell having a first liquid injection port and a second liquid injection port; a stopper assembly arranged in the cylinder shell and connected with the cylinder shell, the stopper assembly having a first through hole and an exhaust passage, the first through hole being in communication with the first liquid injection port, and the exhaust passage being in communication with an intake passage of the screw compressor; a piston assembly arranged in the cylinder shell, the piston assembly comprising a connecting rod part and an end part, the connecting rod part being connected to the stopper assembly and having a second through hole in communication with the first through hole, the connecting rod part being arranged in the end part and connected with the end part; and a slide valve assembly arranged in the cylinder shell and in sliding connection with the cylinder shell, the slide valve assembly and the cylinder shell enclosing a compression cavity and a liquid storage cavity, the liquid storage cavity being in communication with the second liquid injection port, the slide valve assembly having a containing cavity, the end part being arranged in the containing cavity and in sealing connection with the inner wall of the containing cavity, and the second through hole being in communication with the containing cavity; wherein the piston assembly is configured to deliver high-pressure liquid into the containing cavity through the second through hole, push the slide valve assembly to move along the length direction and separate from the stopper assembly, so as to make the compression cavity in communication with the exhaust passage. By injecting high-pressure liquid into the first liquid injection port, the high-pressure liquid enters the containing cavity through the first through hole and the second through hole, thereby pushing the slide valve assembly to move along the length direction, so as to make the compression cavity in communication with the exhaust passage, and part of the gas in the compression cavity can be discharged through the exhaust passage, thereby achieving the purpose of adjusting the gas amount in the compression cavity. The structure directly acts on the slide valve assembly with high-pressure liquid, and the slide valve assembly is pushed by the high-pressure liquid, thereby facilitating the movement of the slide valve assembly along the length direction, reducing the difficulty of sliding of the slide valve assembly, and being conducive to quickly adjusting the gas amount in the compression cavity. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0022] In order to more completely understand the present application and its beneficial effects, the following will be described in conjunction with the drawings, wherein the same reference numerals in the following description represent the same parts.

[0023] Figure 1 is a front sectional view of a screw compressor provided in an exemplary embodiment of the present disclosure; Figure 2 is a front sectional view of a cylinder housing provided in an exemplary embodiment of the present disclosure, in which a slide valve assembly is in a closed state; Figure 3 is a schematic view of a partial structure at a liquid storage cavity provided in an exemplary embodiment of the present disclosure; Figure 4 is a front sectional view of a cylinder housing provided in an exemplary embodiment of the present disclosure, in which a slide valve assembly is in an open state; Figure 5 is a perspective view of a cylinder housing provided in an exemplary embodiment of the present disclosure; Figure 6 is a side view of a cylinder housing provided in an exemplary embodiment of the present disclosure; Figure 7 is a perspective view of a piston assembly provided in an exemplary embodiment of the present disclosure; Figure 6 is a partial enlarged view of region A in FIG. 8; Figure 8 is a perspective view of a stopper assembly provided in an exemplary embodiment of the present disclosure; Figure 9 is a front sectional view of a stopper assembly provided in an exemplary embodiment of the present disclosure; Figure 10 is a perspective view of a piston assembly provided in an exemplary embodiment of the present disclosure; Figure 11 is a front sectional view of a piston assembly provided in an exemplary embodiment of the present disclosure; Figure 12 is a perspective view of a slide valve assembly provided in an exemplary embodiment of the present disclosure; Figure 13 is a front sectional view of a slide valve assembly provided in an exemplary embodiment of the present disclosure.

[0024] BRIEF DESCRIPTION OF REFERENCE NUMERALS: 10 - cylinder housing; 11 - first liquid injection port; 12 - second liquid injection port; 13 - compression chamber; 14 - liquid storage chamber; 141 - first side wall; 142 - second side wall; 15 - mounting groove; 16 - dovetail groove; 161 - first contact surface; 162 - second contact surface; 20 - stop block assembly; 21 - first flow hole; 22 - exhaust passage; 23 - fixing groove; 24 - positioning block; 25 - mounting portion; 26 - connecting portion; 261 - first connecting surface; 262 - second connecting surface; 27 - blowdown port; 30 - piston assembly; 31 - connecting rod portion; 311 - second flow hole; 312 - positioning groove; 313 - annular groove; 314 - first sealing groove; 32 - end portion; 321 - second sealing groove; 33 - first sealing portion; 34 - second sealing portion; 35 - elastic portion; 40 - slide valve assembly; 41 - accommodating cavity; 42 - body; 43 - spacing portion; 44 - fitting portion; 441 - first fitting surface; 442 - second fitting surface; 50 - rotor assembly; 60 - screw compressor; 61 - gas inlet passage; X - length direction; Y - width direction. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person skilled in the art without creative labor are within the protection scope of the present application.

[0026] As a core power equipment in modern industry, especially in the fields of petroleum chemical industry, steel smelting, biological medicine, printing and dyeing textile, etc., the core value of oil-free liquid injection screw compressor lies in that it can provide absolutely clean and oil-free compressed steam or process gas. With the continuous expansion of industrial production scale, the increasingly fine process requirements and the increasingly stringent energy efficiency requirements under the "double carbon" target, the operating efficiency of the compressor, especially the gas flow regulation performance under part load conditions, has become a key indicator to measure the advancement and economy of the equipment. At present, the mainstream and mature solutions for flow regulation of such compressors in the industry mainly include two types: frequency regulation and circulation backflow regulation.

[0027] Variable frequency regulation technology changes the power frequency supplied to the main motor of the compressor through the frequency converter, thereby steplessly adjusting the motor speed and changing the rotation speed of the screw rotor, achieving a nearly proportional relationship between the displacement and the rotation speed. In theory, this is an extremely ideal adjustment method: when the flow needs to be reduced, the motor speed decreases synchronously, and its input power decreases approximately in proportion to the third power of the rotation speed, so it has excellent energy-saving potential in a large adjustment range. At the same time, it realizes smooth and stepless adjustment of the flow, and has less impact on the power grid and mechanical system. However, the application of this technology has limitations that cannot be ignored. First, the initial investment cost is high, and the high-power frequency converter and its supporting harmonic control and cooling system are expensive. Second, the compressor efficiency will decrease significantly in the low-speed operating range. Too low a speed will cause the relative proportion of the leakage gap between the screw rotors to increase, the internal leakage to intensify, and the volumetric efficiency to decrease sharply; third, the frequency converter itself will generate harmonics, pollute the power grid, require additional filtering devices, and have poor long-term stable operation reliability, high maintenance costs, and other problems.

[0028] Recycle regulation is a classic and simple "bypass" regulation method. This method installs a recycle pipe and a regulating valve on the compressor outlet pipeline, and the excess compressed gas exceeding the user's demand is introduced back to the compressor inlet after cooling. Its essence is to make the compressor always operate near the rated operating point, and match the external low demand by "creating and recycling" internal flow. The biggest advantage of this method is that the initial investment is extremely low, only the pipeline, valve and cooler need to be added, and the technical threshold is low and easy to implement. However, the energy efficiency cost is extremely high. The compressor runs at full load or near full load power, consumes rated power, but the effective work output is only a part, and a large amount of energy is wasted in the compression, cooling, and re-compression cycle. From the second law of thermodynamics, this is a "high-quality low-use" energy waste process. Especially at part load, for example, when the actual demand is only 50% of the rated flow, using recycle regulation means that nearly half of the input power is wasted in the recycle and cooling process, and the operating cost is high. In addition, the recycled gas usually needs to be cooled to control the inlet temperature, which increases the load and energy consumption of the cooling system.

[0029] Compared with the first two modes, the slide valve adjustment is a volume direct adjustment mechanism based on the structural innovation of the compressor. The slide valve moves along the axial direction, and can continuously change the effective working length of the screw rotor. When it is necessary to reduce the exhaust volume, the slide valve moves to the exhaust end, and opens the bypass port connected to the suction end in advance, so that part of the suction gas is returned to the suction chamber before compression, and only the gas in the effective length of the rotor is compressed. The advantages of this adjustment mode are: first, the slide valve adjustment reduces the load by reducing the actual compression volume, avoiding the huge energy loss of "full pressure head circulation" in the reflux adjustment. Its power consumption is close to being proportional to the actual exhaust volume under partial load conditions, and the overall energy efficiency under partial load is much higher than that of the reflux adjustment. At the same time, compared with the efficiency decay of the frequency conversion adjustment in the low speed area, the rotor speed remains unchanged during the slide valve adjustment, maintaining high volumetric efficiency and adiabatic efficiency. Second, the slide valve can realize stepless and continuous adjustment of the flow, and is not limited by the minimum speed, which can meet the various complex working condition requirements from low load start to full load operation in chemical production, and provides great operation flexibility. Third, the slide valve adjustment is essentially a "unloading" process, which reduces the load and shaft power of the compressor, thereby reducing the stress on the rotor, the load on the bearing, and the heat that needs to be taken away by the liquid injection system, which helps to improve the service life of the mechanical parts and the operation reliability of the whole machine.

[0030] Although the slide valve adjustment has significant advantages, applying the slide valve adjustment mechanism to the oil-free screw compressor has certain technical challenges. The liquid injection medium inside the cavity of the oil-free screw compressor is generally water or process gas condensate, which has poor lubricity and is not conducive to the movement of the slide valve, which makes it difficult to adjust the amount of compressed gas in the compressor. In addition, the high-pressure liquid used to drive the movement of the slide valve also needs to meet the requirements of oil-free contact, and ordinary hydraulic structure devices cannot meet the requirements. Under high temperature working conditions, the slide valve body and the compressor shell are subject to thermal expansion, and the gap between the slide valve body and the rotor needs to be set and the slide valve body needs to be limited.

[0031] Please refer to Figure 1 、 Figure 2 、 Figure 4 and Figure 8 , the present application provides a screw compressor, which comprises a cylinder shell 10, a stop block assembly 20, a piston assembly 30 and a slide valve assembly 40.

[0032] The cylinder shell 10 has a first liquid injection port 11 and a second liquid injection port 12. The baffle assembly 20 is arranged in the cylinder shell 10 and connected with the cylinder shell 10, and has a first flow hole 21 and an exhaust passage 22, the first flow hole 21 is communicated with the first liquid injection port 11, and the exhaust passage 22 is communicated with the inlet passage 61 of the screw compressor 60. The piston assembly 30 is arranged in the cylinder shell 10, and includes a connecting rod part 31 and a head part 32, the connecting rod part 31 is connected with the baffle assembly 20 and has a second flow hole 311 communicated with the first flow hole 21, and the connecting rod part 31 is arranged in the head part 32 and connected with the head part 32. The slide valve assembly 40 is arranged in the cylinder shell 10 and connected with the cylinder shell 10 in a sliding mode, and the slide valve assembly 40 and the cylinder shell 10 enclose a compression cavity 13 and a liquid storage cavity 14, the liquid storage cavity 14 is communicated with the second liquid injection port 12, and the slide valve assembly 40 has a containing cavity 41, the head part 32 is arranged in the containing cavity 41 and connected with the inner wall of the containing cavity 41 in a sealing mode, and the second flow hole 311 is communicated with the containing cavity 41. The piston assembly 30 is configured to: deliver high-pressure liquid into the containing cavity 41 through the second flow hole 311, push the slide valve assembly 40 to move along the length direction X and separate from the baffle assembly 20, so that the compression cavity 13 is communicated with the exhaust passage 22. The length direction X is the direction of the length of the cylinder shell 10.

[0033] It can be understood that the cylinder shell 10 of the screw compressor 60 has the compression cavity 13, the inside of the compression cavity 13 is provided with a female rotor and a male rotor, and the two rotors are used to compress the gas entering the compression cavity 13. In order to facilitate the adjustment of the amount of the gas compressed in the compression cavity 13, the baffle assembly 20, the piston assembly 30 and the slide valve assembly 40 are cooperated to discharge part of the gas in the compression cavity 13, and the part of the gas discharged can enter the inlet passage 61 of the screw compressor 60 and be taken as the new inlet gas into the inside of the compression cavity 13. The screw compressor 60 can be used to compress water vapor, process gas, special gas, food or medical gas and other gases with high cleanliness requirements.

[0034] The baffle assembly 20 is fixed at one end of the cylinder shell 10 close to the inlet passage 61, and the baffle assembly 20 has the first flow hole 21 communicated with the first liquid injection port 11 on the cylinder shell 10. The connecting rod part 31 of the piston assembly 30 is connected with the baffle assembly 20, and has the second flow hole 311 communicated with the first flow hole 21, and the end of the connecting rod part 31 and the head part 32 connected with the end are embedded into the containing cavity 41 of the slide valve assembly 40. The pipeline structure can be connected at the first liquid injection port 11, and the liquid inlet valve and the liquid outlet valve can be arranged on the pipeline structure. Figure 2As shown, when the piston assembly 30 is in the initial position, one end of the piston assembly 30 is in close contact with the block assembly 20, and the piston assembly 30 isolates the compression cavity 13 from the exhaust passage 22 on the block assembly 20, so that the gas in the compression cavity 13 cannot enter the intake passage 61 through the exhaust passage 22. If it is necessary to adjust the exhaust capacity of the screw compressor 60, the liquid inlet valve at the first liquid inlet 11 can be opened, and high-pressure liquid can be transported to the first liquid inlet 11 through the pipeline structure, and then pass through the first flow hole 21 and the second flow hole 311 in sequence, and then be discharged from the opening at one end of the second flow hole 311. The discharged high-pressure liquid is located between the end head 32 and the inner wall on one side of the containing cavity 41. Since the piston assembly 30 is fixedly connected with the block assembly 20, and the slide valve assembly 40 is slidably connected with the cylinder shell 10, after the high-pressure liquid is injected from the first liquid inlet 11, the high-pressure liquid acts on the piston assembly 30 and the slide valve assembly 40, thereby pushing the slide valve assembly 40 to move away from the block assembly 20 along the length direction X, the connection between the slide valve assembly 40 and the block assembly 20 is separated, and a space is formed between the slide valve assembly 40 and the block assembly 20, so that the gas in the compression cavity 13 can enter the exhaust passage 22 through the space, and then enter the intake passage 61 through the exhaust passage 22, thereby realizing the adjustment of the gas capacity in the compression cavity 13. The degree of adjustment can be determined according to the distance between the slide valve assembly 40 and the block assembly 20, the greater the distance between them, the greater the degree of adjustment, until the slide valve assembly 40 moves to the maximum distance, and reaches the maximum adjustment degree, at this time, the amount of gas discharged by the screw compressor 60 is the smallest. The structure directly acts on the slide valve assembly 40 by high-pressure liquid, and pushes the slide valve assembly 40 by high-pressure liquid, so as to facilitate the movement of the slide valve assembly 40 along the length direction X, and reduce the difficulty of sliding of the slide valve assembly 40, which is conducive to the rapid adjustment of the gas capacity in the compression cavity 13. The structure is suitable for working environments with a compressor outlet pressure less than 2.5 MPa and an outlet temperature less than 220℃, and the components of the high-pressure liquid can be the same as those of the compressed gas.

[0035] If it is necessary to make the separated slide valve assembly 40 and the block assembly 20 re-adhere to connect, a pipeline structure can also be arranged at the position of the second liquid injection port 12, and the pipeline structure is also provided with an inlet valve and an outlet valve. The inlet valve on the pipeline structure is opened, and the outlet valve is closed. Then the inlet valve on the pipeline structure at the first liquid injection port 11 is closed, and the outlet valve at the first liquid injection port 11 is opened. High-pressure liquid is injected into the second liquid injection port 12, and the high-pressure liquid in the second liquid injection port 12 enters the liquid storage cavity 14, thereby pushing the slide valve assembly 40, so that the slide valve assembly 40 moves along the length direction X towards the direction of the block assembly 20 until the slide valve assembly 40 and the block assembly 20 are reconnected. The compressed cavity 13 is isolated from the exhaust passage 22 by the slide valve assembly 40, so as to avoid that the gas in the compressed cavity 13 enters the exhaust passage 22. In this process, the high-pressure liquid in the containing cavity 41 is discharged through the second overflow hole 311, the first overflow hole 21 and the first liquid injection 11. In the process of moving of the slide valve assembly 40, the amount of gas in the compressed cavity 13 can also be adjusted.

[0036] Please refer to Figure 8 、 Figure 9 、 Figure 10 and Figure 11 , in combination with the above embodiments, in some embodiments, the block assembly 20 has a fixed groove 23, and the end of the connecting rod part 31 away from the end head part 32 is embedded into the fixed groove 23 and connected with the block assembly 20. The connecting rod part 31 has a positioning groove 312, and the block assembly 20 includes a positioning block 24 arranged on the inner wall of the fixed groove 23 and embedded into the positioning groove 312.

[0037] It can be understood that the fixed groove 23 is arranged in the block assembly 20 along the length direction X, and the end of the connecting rod part 31 away from the end head part 32 is embedded into the fixed groove 23 and the connecting rod part 31 is connected with the block assembly 20 by bolts. For the part of the connecting rod part 31 in the fixed groove 23, the positioning groove 312 is arranged on the connecting rod part 31, and the positioning block 24 is arranged on the inner wall of the fixed groove 23 and embedded into the positioning groove 312, so as to form a close fit with the positioning groove 312. Through this structure, the circumferential rotation of the connecting rod part 31 when the connecting rod part 31 is connected with the block assembly 20 can be avoided to a certain extent, and the stability during the connection of the two can be ensured. The positioning block 24 can be a flexible structure and can be deformed to a certain extent under extrusion, so as to facilitate the embedding of the connecting rod part 31 into the fixed groove 23.

[0038] Please refer to Figure 5 and Figure 8 , in combination with the above embodiments, in some embodiments, the cylinder housing 10 has a mounting groove 15, and the block assembly 20 further includes a mounting part 25 embedded into the mounting groove 15 and detachably connected with the cylinder housing 10.

[0039] It can be understood that the mounting portion 25 on the block assembly 20 can be embedded into the mounting groove 15 on the cylinder shell 10, and then the mounting portion 25 and the cylinder shell 10 are connected by bolts. This structure facilitates the disassembly and assembly of the block assembly 20, and facilitates the disassembly and assembly of the piston assembly 30 and the spool valve assembly 40, and facilitates the inspection and maintenance of these structures.

[0040] Please refer to Figure 10 and Figure 11 , in combination with the above embodiments, in some embodiments, the connecting rod portion 31 has an annular groove 313 arranged in the circumferential direction, the annular groove 313 is in communication with the second flow hole 311, and the annular groove 313 is in communication with the first flow hole 21.

[0041] It can be understood that the annular groove 313 is arranged on the connecting rod portion 31, the annular groove 313 is in communication with the inlet of the second flow hole 311, and the position of the annular groove 313 corresponds to the position of the first flow hole 21, and the two are also in communication. Even if the connecting rod portion 31 rotates during assembly with the block assembly 20, causing the second flow hole 311 and the first flow hole 21 not to be arranged opposite each other, the high-pressure liquid in the first flow hole 21 can still first enter the annular groove 313, and then enter the second flow hole 311 along the flow channel of the annular groove 313. That is, this structure ensures that the first flow hole 21 can be in communication with the second flow hole 311 through the annular groove 313, reducing the difficulty of installing the connecting rod portion 31, and facilitating the smooth flow of high-pressure liquid.

[0042] Please refer to Figure 10 and Figure 11 , in combination with the above embodiments, in some embodiments, the connecting rod portion 31 has a plurality of first sealing grooves 314 arranged in the circumferential direction, and the plurality of first sealing grooves 314 are arranged on both sides of the annular groove 313 along the length direction X. The piston assembly 30 includes a plurality of first sealing portions 33, each first sealing portion 33 is arranged in a first sealing groove 314, and the connecting rod portion 31 is sealed and connected with the block assembly 20 through the first sealing portion 33.

[0043] It can be understood that the first sealing groove 314 is arranged on the left and right sides of the connecting rod part 31 relative to the annular groove 313, and the number of the first sealing groove 314 on the left and right sides of the annular groove 313 can be one or more. The first sealing part 33 is arranged in each first sealing groove 314, and the first sealing part 33 and the first sealing groove 314 are annular structures. The first sealing part 33 protrudes from the corresponding first sealing groove 314, so that when one end of the connecting rod part 31 is embedded into the fixed groove 23, the first sealing part 33 can be tightly attached to the inner wall of the fixed groove 23, and the connecting rod part 31 is sealingly connected to the inner wall of the fixed groove 23 through the first sealing part 33. Thus, the leakage of high-pressure liquid flowing through the annular groove 313 is avoided, and the sealing performance of the connection between the connecting rod part 31 and the inner wall of the fixed groove 23 is improved. The first sealing part 33 can be made of silica gel, rubber or the like.

[0044] Please refer to Figure 10 and Figure 11 , in combination with the above embodiments, in some embodiments, the end head part 32 has a plurality of second sealing grooves 321 arranged in the circumferential direction, and the piston assembly 30 further comprises a plurality of second sealing parts 34, each of which is arranged in a second sealing groove 321, and the end head part 32 is sealingly connected to the inner wall of the containing cavity 41 through the second sealing part 34.

[0045] It can be understood that a plurality of second sealing grooves 321 are arranged on the end head part 32, and a second sealing part 34 is arranged in each second sealing groove 321. The second sealing part 34 and the second sealing groove 321 are annular structures, the cross section of the end head part 32 and the containing cavity 41 is a circular structure, and the second sealing part 34 sealingly connects the end head part 32 to the inner wall of the containing cavity 41. The end head part 32 is located inside the containing cavity 41, and when high-pressure liquid is injected into the first liquid injection port 11, the high-pressure liquid will enter between the end head part 32 and the right inner wall of the containing cavity 41. At this time, the high-pressure liquid is located on the right side of the end head part 32, and the second sealing groove 321 and the second sealing part 34 arranged thereon can prevent the high-pressure liquid from leaking to the left side of the end head part 32, thereby sealing the high-pressure liquid well. The second sealing part 34 can be made of silica gel, rubber or the like.

[0046] Please refer to Figure 2 and Figure 4 , in combination with the above embodiments, in some embodiments, the piston assembly 30 further comprises an elastic part 35, which is arranged on the side of the end head part 32 facing the stop block assembly 20 and is sleeved on the connecting rod part 31. The two ends of the elastic part 35 respectively abut against the end head part 32 and the inner wall of the containing cavity 41.

[0047] It can be understood that the elastic part 35 can be a spring which is located inside the accommodating cavity 41 and sleeved on the connecting rod part 31. When the spool assembly 40 and the block assembly 20 are in the initial state, that is, no high-pressure liquid is injected into the first liquid injection port 11, and the two are also in the connected state, the elastic part 35 is in the compressed state, at this time, the elastic part 35 will extrude the spool assembly 40, the spool assembly 40 extrudes the block assembly 20, so that the spool assembly 40 and the block assembly 20 have high connection stability, avoiding that the two are not connected tightly, and the gas in the compression cavity 13 leaks into the exhaust passage 22. When high-pressure liquid is injected into the first liquid injection port 11, the high-pressure liquid pushes the spool assembly 40 to move away from the block assembly 20 along the length direction X, and the spool assembly 40 extrudes the elastic part 35 during movement, so that the elastic part 35 is forced to shrink. In the case of injecting high-pressure liquid into the second liquid injection port 12 and moving the spool assembly 40 towards the block assembly 20, the high-pressure liquid in the liquid storage cavity 14 can push the spool assembly 40, and at the same time, the elastic part 35 can also push the spool assembly 40, facilitating the rapid discharge of high-pressure liquid in the accommodating cavity 41, and being beneficial to the rapid connection of the spool assembly 40 and the block assembly 20. In this process, the high-pressure liquid can stay in the liquid storage cavity 14 to provide extrusion force to the spool assembly 40, so that the spool assembly 40 and the block assembly 20 are connected more tightly.

[0048] Please refer to Figure 2 and Figure 3 , in combination with the above embodiments, in some embodiments, the liquid storage cavity 14 has a first side wall 141 and a second side wall 142 which are spaced apart along the length direction X, and the spool assembly 40 comprises a body 42 and a spacing part 43. The body 42 is slidably connected to the cylinder housing 10. The spacing part 43 is arranged in the liquid storage cavity 14 and connected with the first side wall 141, and is used for spacing the first side wall 141 and the second side wall 142. Along the length direction X, the second side wall 142 has a maximum distance L1 from the second liquid injection port 12, and the spacing part 43 has a size L2 along the length direction X, and L2≥L1 is satisfied.

[0049] It can be understood that the first side wall 141 and the second side wall 142 in the liquid storage cavity 14 are spaced apart along the length direction X, in order to ensure that there is a gap between the first side wall 141 and the second side wall 142, that is, in order to ensure that the liquid storage cavity 14 can exist, a spacing portion 43 can be arranged on the first side wall 141, when the spool valve assembly 40 moves away from the stopper assembly 20 and moves to the maximum distance, the spacing portion 43 can abut against the second side wall 142, so as to avoid the first side wall 141 and the second side wall 142 from being attached. The size of the spacing portion 43 in the length direction X is greater than or equal to the maximum distance between the second side wall 142 and the second liquid inlet 12, which is beneficial to the high-pressure liquid entering the liquid storage cavity 14 through the second liquid inlet 12. If the first side wall 141 and the second side wall 142 are attached, the spool valve assembly 40 will block the second liquid inlet 12, which is not conducive to the high-pressure body fluid entering the liquid storage cavity 14.

[0050] Please refer to Figure 5 , Figure 6 , Figure 7 , Figure 12 and Figure 13 , in combination with the above embodiments, in some embodiments, the cylinder housing 10 has two dovetail grooves 16 spaced apart along the width direction Y, the dovetail groove 16 extends along the length direction X, and the spool valve assembly 40 includes two matching portions 44 spaced apart along the width direction Y, each matching portion 44 is embedded into one dovetail groove 16. The dovetail groove 16 has a first contact surface 161 and a second contact surface 162 connected, the matching portion 44 has a first matching surface 441 and a second matching surface 442 connected, the first matching surface 441 is connected to the first contact surface 161, and the second matching surface 442 is connected to the second contact surface 162. Wherein, the width direction Y is the direction in which the width of the cylinder housing 10 is located.

[0051] It can be understood that two dovetail grooves 16 are arranged inside the cylinder housing 10, the two matching portions 44 on the spool valve assembly 40 are in dovetail structure and are embedded into the corresponding dovetail grooves 16, and the matching portion 44 can slide in the dovetail groove 16 along the length direction X. The dovetail groove 16 plays a certain guiding role on the matching portion 44, so that the entire spool valve assembly 40 moves along the length direction X. When the matching portion 44 is connected with the dovetail groove 16, the first matching surface 441 on the matching portion 44 is connected with the first contact surface 161 of the dovetail groove 16, and the second matching surface 442 on the matching portion 44 is connected with the second contact surface 162 of the dovetail groove 16. Through this surface-to-surface matching mode, the matching portion 44 and the dovetail groove 16 are stably connected, so as to avoid the spool valve assembly 40 from shaking left and right or rotating circumferentially during sliding.

[0052] Please refer to Figure 5 , Figure 6 , Figure 7 andFigure 8 In some embodiments, the stopper assembly 20 includes two connecting portions 26 spaced apart along the width direction Y, and each connecting portion 26 is embedded into a corresponding dovetail groove 16. The connecting portion 26 includes a first connecting surface 261 connected to the first contact surface 161 and a second connecting surface 262 connected to the second contact surface 162.

[0053] It can be understood that the two connecting portions 26 on the stopper assembly 20 are in dovetail structure and can be embedded into the corresponding dovetail groove 16. The first connecting surface 261 on the connecting portion 26 is connected to the first contact surface 161 on the dovetail groove 16, and the second connecting surface 262 on the connecting portion 26 is connected to the second contact surface 162 on the dovetail groove 16. Through the surface-to-surface cooperation, the connecting portion 26 can be embedded into the corresponding dovetail groove 16 during the installation of the stopper assembly 20, and the dovetail groove 16 can limit the stopper assembly 20 to prevent the stopper assembly 20 from shaking left and right or rotating in the circumferential direction during the installation, thereby improving the stability during the installation.

[0054] Referring to Figure 7 In some embodiments, the first contact surface 161 and the second contact surface 162 have an included angle a satisfying 55°≤a≤70°.

[0055] It can be understood that when the included angle between the first contact surface 161 and the second contact surface 162 is set to 55° to 70°, the machining of the milling cutter is facilitated, and the cutter head works better under stress. When the angle a is too large or too small, the cutter will be worn out and even broken.

[0056] Referring to Figure 1 In some embodiments, the inner wall of the dovetail groove 16 and the surface of the cooperating portion 44 are provided with a coating structure for reducing the friction when the cooperating portion 44 slides in the dovetail groove 16.

[0057] It can be understood that the inner wall of the dovetail groove 16 and the surface of the cooperating portion 44 are provided with a coating structure, which can be a polytetrafluoroethylene coating, an ultrahigh molecular weight polyethylene coating, a polyurethane lubricating coating, a metal alloy coating, etc. By setting the coating structure, the friction of the cooperating portion 44 when sliding in the dovetail groove 16 can be reduced, which is conducive to the smooth sliding of the slide valve assembly 40.

[0058] Referring to Figure 8 In some embodiments, the stopper assembly 20 has a blowdown port 27 for discharging liquid between the stopper assembly 20 and the slide valve assembly 40.

[0059] It can be understood that the block assembly 20 is also provided with a drain port 27, the number of the drain port 27 can be one or multiple, the drain port 27 is in a semicircular structure and extends along the length direction X. When there is liquid between the block assembly 20 and the slide valve assembly 40, such as part of the high-pressure liquid leaking between the block assembly 20 and the slide valve assembly 40, the part of the liquid can be discharged through the drain port 27, avoiding the impact of these liquids on the operation of the compressor.

[0060] Please refer to Figure 2 and Figure 4 , in combination with the above embodiments, in some embodiments, the distance between the slide valve assembly 40 and the block assembly 20 along the length direction X is H1, the screw compressor 60 further comprises a rotor assembly 50, the size of the rotor assembly 50 in the compression chamber 13 along the length direction X is H2, and 0≤H1 / H2≤0.4 is satisfied.

[0061] It can be understood that when the high-pressure liquid is not injected through the first liquid injection port 11, the slide valve assembly 40 is connected with the block assembly 20, the distance H1 between the slide valve assembly 40 and the block assembly 20 along the length direction X is 0, then H1 / H2 is 0. At this time, the gas in the compression chamber 13 cannot be discharged through the exhaust passage 22, and the gas in the compression chamber 13 is completely discharged through the exhaust end of the screw compressor 60; when the high-pressure liquid is injected through the first liquid injection port 11, the high-pressure liquid pushes the slide valve assembly 40 to move away from the block assembly 20 along the length direction X, and when it moves to the maximum distance, at this time, H1 / H2 is 0.4, part of the gas in the compression chamber 13 is discharged through the exhaust passage 22, and another part of the gas is discharged through the exhaust end of the screw compressor 60, and the gas discharged through the exhaust passage 22 accounts for 40% of the total gas in the compression chamber 13.

[0062] In combination with the above structural features, taking a water vapor screw compressor 60 as an example, the inlet pressure is 0.0877 MPaA, the exhaust pressure is 0.45 MPaA, the liquid injection medium is liquid water, and the high-pressure liquid used to drive the slide valve assembly 40 is water. The total length of the compressor cylinder shell 10 is 1165 mm, the maximum moving distance of the slide valve assembly 40 is designed to be 250 mm, and the gas capacity adjustment range is 70%~100%. The force analysis of the slide valve assembly 40 is as follows: when the slide valve assembly 40 moves 200 mm (opening process), at least 0.94 MPaG of water injection pressure is required, and different water injection pressures can be obtained according to different moving distances of the slide valve assembly 40.

[0063]

[0064] The application further provides a gas volume adjusting method of the screw compressor, which is applied to the screw compressor, and the method comprises the following steps: when the exhaust volume of the screw compressor 60 is reduced, high-pressure liquid is delivered to the first flow hole 21 of the block assembly 20 through the first liquid injection port 11 of the cylinder shell 10, so that the high-pressure liquid enters the containing cavity 41 of the slide valve assembly 40 through the second flow hole 311. The high-pressure liquid pushes the slide valve assembly 40 to move along the length direction X to the direction away from the block assembly 20, so that the compression cavity 13 is communicated with the exhaust passage 22, and the compressed gas in the compression cavity 13 flows back to the air inlet passage 61 of the screw compressor 60 through the exhaust passage 22.

[0065] In combination with the above embodiments, in some embodiments, the gas volume adjusting method of the screw compressor further comprises the following steps: when the exhaust volume of the screw compressor 60 is increased, the delivery of the high-pressure liquid to the second flow hole 311 is stopped, and the high-pressure liquid is injected into the liquid storage cavity 14 through the second liquid injection port 12 of the cylinder shell 10. Under the thrust of the high-pressure liquid, the slide valve assembly 40 moves along the length direction X to the direction close to the block assembly 20, gradually closes the communication between the compression cavity 13 and the exhaust passage 22, until the slide valve assembly 40 is attached to the block assembly 20, and the exhaust volume of the screw compressor 60 reaches the maximum.

[0066] In the description of the application, the terms “first” and “second” are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as “first” and “second” can explicitly or implicitly include one or more features. In the description of the application, the meaning of “multiple” is two or more, unless otherwise specifically limited.

[0067] In the above embodiments, the description of each embodiment is focused on, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments.

[0068] The embodiments, the implementation manners and the related technical features of the application can be combined or replaced with each other without conflict.

[0069] The above is only the preferred embodiments of the application, and does not limit the application in any form, but any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the application, without departing from the technical solution of the application, still belongs to the scope of the technical solution of the application.

Claims

1. A screw compressor, characterized in that, include: The cylinder housing (10) has a first injection port (11) and a second injection port (12). A stop block assembly (20) is disposed inside the cylinder housing (10). The stop block assembly (20) has a first flow hole (21) and an exhaust passage (22). The first flow hole (21) is connected to the first liquid injection port (11), and the exhaust passage (22) is connected to the intake passage (61) of the screw compressor (60). A piston assembly (30) is disposed within the cylinder housing (10). The piston assembly (30) includes a connecting rod portion (31) and an end head (32). The connecting rod portion (31) is connected to the stop assembly (20) and has a second flow hole (311) communicating with the first flow hole (21). The connecting rod portion (31) passes through the end head (32). A slide valve assembly (40) is disposed inside the cylinder housing (10) and is slidably connected to the cylinder housing (10). The slide valve assembly (40) and the cylinder housing (10) enclose a compression chamber (13) and a liquid storage chamber (14). The liquid storage chamber (14) is connected to the second injection port (12). The slide valve assembly (40) has a receiving cavity (41). The end head (32) is disposed inside the receiving cavity (41) and is sealed to the inner wall of the receiving cavity (41). The second flow hole (311) is connected to the receiving cavity (41). The piston assembly (30) is configured to deliver high-pressure liquid into the receiving cavity (41) through the second flow hole (311), thereby pushing the slide valve assembly (40) to move along the length direction (X) and separate from the stop assembly (20) so that the compression cavity (13) is connected to the exhaust channel (22).

2. The screw compressor according to claim 1, characterized in that, The stop assembly (20) has a fixing groove (23), and one end of the connecting rod (31) away from the end head (32) is embedded in the fixing groove (23) and connected to the stop assembly (20); The connecting rod (31) has a positioning groove (312), and the stop assembly (20) includes a positioning block (24). The positioning block (24) is disposed on the inner wall of the fixing groove (23) and embedded in the positioning groove (312).

3. The screw compressor according to claim 1, characterized in that, The cylinder housing (10) has a mounting groove (15), and the stop assembly (20) further includes a mounting part (25), which is embedded in the mounting groove (15) and is detachably connected to the cylinder housing (10).

4. The screw compressor according to claim 1, characterized in that, The connecting rod portion (31) has an annular groove (313) arranged in the circumferential direction. The annular groove (313) communicates with the second flow hole (311) and the annular groove (313) communicates with the first flow hole (21).

5. The screw compressor according to claim 4, characterized in that, The connecting rod portion (31) has a plurality of first sealing grooves (314) arranged circumferentially, and the plurality of first sealing grooves (314) are respectively arranged on both sides of the annular groove (313) along the length direction (X); The piston assembly (30) includes a plurality of first sealing parts (33), each of the first sealing parts (33) being disposed in a first sealing groove (314), and the connecting rod part (31) being sealed to the stop assembly (20) through the first sealing parts (33).

6. The screw compressor according to claim 1, characterized in that, The end head (32) has a plurality of second sealing grooves (321) arranged circumferentially, and the piston assembly (30) further includes a plurality of second sealing parts (34), each of the second sealing parts (34) being disposed in a second sealing groove (321), and the end head (32) being sealed to the inner wall of the receiving cavity (41) through the second sealing parts (34).

7. The screw compressor according to claim 1, characterized in that, The piston assembly (30) also includes: The elastic part (35) is disposed on the side of the end head (32) facing the stop assembly (20) and sleeved on the connecting rod part (31). The two ends of the elastic part (35) abut against the end head (32) and the inner wall of the receiving cavity (41), respectively.

8. The screw compressor according to claim 1, characterized in that, The liquid storage chamber (14) has a first sidewall (141) and a second sidewall (142) spaced apart along the length direction (X), and the slide valve assembly (40) includes: The main body (42) is slidably connected to the cylinder housing (10); A spacer (43) is disposed in the liquid storage cavity (14) and connected to the first side wall (141). The spacer (43) is used to separate the first side wall (141) and the second side wall (142). Along the length direction (X), there is a maximum distance L1 between the second sidewall (142) and the second injection port (12), and along the length direction (X), the interval (43) has a size L2, satisfying: L2≥L1.

9. The screw compressor according to claim 1, characterized in that, The cylinder housing (10) has two dovetail grooves (16) spaced apart along the width direction (Y), the dovetail grooves (16) extending along the length direction (X), and the slide valve assembly (40) includes two mating parts (44) spaced apart along the width direction (Y), each of the mating parts (44) being embedded in one of the dovetail grooves (16); The dovetail groove (16) has a first contact surface (161) and a second contact surface (162) connected to each other, and the mating part (44) has a first mating surface (441) and a second mating surface (442) connected to each other. The first mating surface (441) is connected to the first contact surface (161), and the second mating surface (442) is connected to the second contact surface (162).

10. The screw compressor according to claim 9, characterized in that, The stop assembly (20) includes two connecting portions (26) spaced apart along the width direction (Y), each connecting portion (26) being embedded in one of the dovetail grooves (16); The connecting part (26) includes a first connecting surface (261) and a second connecting surface (262) connected to each other. The first connecting surface (261) is connected to the first contact surface (161), and the second connecting surface (262) is connected to the second contact surface (162).

11. The screw compressor according to claim 9, characterized in that, The first contact surface (161) and the second contact surface (162) have an included angle α, which satisfies: 55°≤α≤70°.

12. The screw compressor according to claim 9, characterized in that, The inner wall of the dovetail groove (16) and the surface of the mating part (44) are provided with a coating structure, which is used to reduce the friction of the mating part (44) when it slides in the dovetail groove (16).

13. The screw compressor according to claim 1, characterized in that, The baffle assembly (20) has a drain port (27) for discharging liquid between the baffle assembly (20) and the slide valve assembly (40).

14. The screw compressor according to claim 1, characterized in that, The distance H1 of the slide valve assembly (40) away from the stop assembly (20) along the length direction (X) is also included in the screw compressor (60), and the rotor assembly (50) along the length direction (X) has a size H2 in the compression chamber (13) that satisfies: 0≤H1 / H2≤0.

4.

15. A method for regulating the gas volume of a screw compressor, characterized in that, Applied to a screw compressor as described in any one of claims 1 to 14, the method comprises: When the discharge volume of the screw compressor (60) is reduced, high-pressure liquid is delivered to the first flow hole (21) of the baffle assembly (20) through the first liquid injection port (11) of the cylinder housing (10), so that the high-pressure liquid enters the receiving cavity (41) of the slide valve assembly (40) through the second flow hole (311); High-pressure liquid pushes the slide valve assembly (40) to move away from the stop assembly (20) along the length direction (X), so that the compression chamber (13) is connected to the exhaust passage (22), and the compressed gas in the compression chamber (13) flows back to the intake passage (61) of the screw compressor (60) through the exhaust passage (22).

16. The method for regulating the gas volume of a screw compressor according to claim 15, characterized in that, The method further includes: When the discharge volume of the screw compressor (60) is increased, the high-pressure liquid is stopped from being delivered to the second flow hole (311), and high-pressure liquid is injected into the liquid storage chamber (14) through the second liquid injection port (12) of the cylinder housing (10); Under the thrust of the high-pressure liquid, the slide valve assembly (40) moves along the length direction (X) toward the direction of the stop assembly (20), gradually closing the connection between the compression chamber (13) and the exhaust channel (22) until the slide valve assembly (40) and the stop assembly (20) are in contact, and the exhaust volume of the screw compressor (60) reaches its maximum.

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