Screw compressor and control method thereof
By setting a second chamber in the screw compressor and controlling the inlet and exit of pressure fluid, the problems of cumbersome control logic and delay in the prior art are solved, and more timely and efficient load and pressure ratio adjustment is achieved.
Patent Information
- Application Number
- CN202510634556.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-16
- Publication Date
- 2025-07-18
AI Technical Summary
The pressure ratio adjustment and capacity adjustment control process of existing screw compressors is complicated, with delays and requires repeated iterative control logic.
A second chamber is provided in the screw compressor, and the inlet and exit of pressure fluid is controlled through the pressurization port and the pressure relief port. The volume of the second chamber is adjusted by using the pressure fluid control assembly to change the position of the slide valve and realize the adjustment of the effective working length or pressure ratio of the screw rotor.
The control logic of the screw compressor is simplified, the cumbersomeness of the control process is reduced, and more timely and efficient load and pressure ratio adjustment is achieved.
Smart Images
Figure CN120332177A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of air conditioning, and particularly relates to a screw compressor and a control method thereof. Background Art
[0002] Screw compressors usually use the reciprocating motion of a slide valve and an oil piston to achieve capacity regulation or compression ratio regulation. Taking a single-stage two-stage screw compressor as an example, the difference between capacity regulation and compression ratio regulation lies in the structure of the slide valve and its movement stroke. However, whether it is capacity regulation or compression ratio regulation, the compressor receives a whole-machine control signal, and through the opening and closing of the solenoid valve, under the action of the suction and discharge pressure difference, lubricating oil enters and exits the oil cylinder, causing the reciprocating motion of the slide valve and the oil piston, thereby achieving the control requirements or purposes of the whole machine; among them, compression ratio regulation is based on the actually monitored suction and discharge pressures of the whole machine, uses control logic to calculate the ratio of the discharge pressure to the suction pressure, controls the opening and closing of the solenoid valve to adjust the movement of the slide valve, makes the external compression ratio equal to the internal compression ratio, eliminates the pressure loss caused by under-compression or over-compression, and achieves efficient design; capacity regulation is based on the actually monitored capacity load of the whole machine, uses control logic to determine whether the actual operating load reaches the target load, and then controls the opening and closing of the solenoid valve to adjust the movement of the slide valve, making the compressor load or unload to achieve the load regulation of the whole machine.
[0003] Whether it is compression ratio regulation or capacity regulation, there will be a process of repeated iteration of the control logic, and then corresponding adjustment instructions are sent to the compressor, and the control process is relatively cumbersome and there is a delay. Summary of the Invention
[0004] Therefore, the present invention provides a screw compressor and a control method thereof, which can overcome the technical problems in the related art that the compression ratio regulation or capacity regulation of the screw compressor needs to be achieved through repeated iteration of the control logic, and the control process is cumbersome and there is a delay.
[0005] To solve the above problems, the present invention provides a screw compressor, including a compressor body in which a compression chamber is formed. A screw rotor is disposed in the compression chamber. The screw compressor further includes an adjustment assembly for adjusting the pressure ratio or capacity of the screw compressor. The adjustment assembly includes a slide valve and a piston fixedly connected to the slide valve. A piston chamber is further formed in the compressor body. The piston is located in the piston chamber and divides the piston chamber into an independent first chamber and a second chamber. Wherein, the second chamber is on the side of the first chamber away from the slide valve. The second chamber is configured with a pressure-inlet port and a pressure-relief port communicating therewith. The screw compressor further includes a pressure fluid control assembly. The pressure fluid control assembly can be controlled to increase pressure fluid into the second chamber via the pressure-inlet port or reduce pressure fluid from the second chamber via the pressure-relief port, so as to drive the slide valve to move by adjusting the volume of the second chamber, thereby changing the effective working length of the screw rotor or the pressure ratio of the screw rotor.
[0006] In some embodiments, the pressure fluid control assembly includes a loading pipeline controllably communicating with the outlet of a pressure fluid source and an unloading pipeline controllably communicating with the return port of a pressure fluid unloading component. A first flowmeter is connected in series on the loading pipeline, and a second flowmeter is connected in series on the unloading pipeline.
[0007] In some embodiments, a first solenoid valve is further connected in series on the loading pipeline, and a second solenoid valve is further connected in series on the unloading pipeline.
[0008] In some embodiments, the pressure fluid control assembly includes a loading pipeline controllably communicating with the outlet of a pressure fluid source and an unloading pipeline controllably communicating with the return port of a pressure fluid unloading component. The loading pipeline and the unloading pipeline share a third flowmeter.
[0009] In some embodiments, the third flowmeter is connected in series on the loading pipeline and divides the loading pipeline into a loading downstream pipe section connected to the pressure-inlet port and a loading upstream pipe section connected to the outlet and capable of being controllably opened and closed. The unloading pipeline has an unloading upstream pipe section communicating with the loading upstream pipe section and capable of being controllably opened and closed, and an unloading downstream pipe section connected between the third flowmeter and the return port. A first solenoid valve is connected in series on the loading upstream pipe section, and a second solenoid valve is connected in series on the unloading downstream pipe section.
[0010] In some embodiments, the unloading upstream pipe section communicates with the loading upstream pipe section at a first position. A first check valve is connected in series on the loading upstream pipe section between the first position and the outlet. The first check valve is conductive in the direction from the outlet to the pressure-inlet port and cut off in the reverse direction. A second check valve is connected in series on the unloading upstream pipe section. The second check valve is conductive in the direction from the pressure-relief port to the third flowmeter and cut off in the reverse direction.
[0011] In some embodiments, the piston and the sliding valve are fixed as a whole via a piston rod. An elastic member is also provided in the first cavity. The elastic member is sleeved on the piston rod and clamped between an end surface of the piston facing away from the second cavity and an inner wall surface of the first cavity.
[0012] The present invention also provides a control method for the screw compressor as described above, comprising the following steps:
[0013] Acquire a target operating condition of the screw compressor, and acquire a target pressure fluid volume V0 of the second chamber corresponding to the target operating condition according to the target operating condition;
[0014] Acquire the real-time pressure fluid volume V of the second chamber;
[0015] The relationship between the real-time pressure fluid volume V and the target pressure fluid volume V0 is determined to control the pressure fluid regulating component to increase pressure fluid into the second chamber or to reduce pressure fluid from the second chamber.
[0016] In some embodiments, determining the relationship between the real-time pressure fluid volume V and the target pressure fluid volume V0 to control whether the pressure fluid control component adds pressure fluid to the second chamber or reduces pressure fluid from the second chamber specifically includes:
[0017] When V=V0, the pressure fluid regulating component is controlled to neither add pressure fluid to the second chamber nor reduce pressure fluid from the second chamber so that the position of the slide valve remains unchanged; or,
[0018] When V>V0, the pressure fluid regulating component is controlled to reduce the pressure fluid from the second chamber, so that the slide valve slides close to the second chamber to reduce the effective working length of the screw rotor, until the pressure fluid is stopped from being reduced when V=V0; or,
[0019] When V<V0, the pressure fluid regulating component is controlled to add pressure fluid into the second chamber to make the slide valve slide away from the second chamber to increase the effective working length of the screw rotor, until the pressure fluid is stopped from being added when V=V0.
[0020] In some embodiments, when the screw compressor includes a first flow meter, a second flow meter, a first solenoid valve, and a second solenoid valve,
[0021] When V = V0, control the first solenoid valve and the second solenoid valve to be in a cut-off state; when V > V0, control the second solenoid valve to conduct and the first solenoid valve to cut off, and when the real-time flow rate detected by the second flowmeter is V - V0, control the second solenoid valve to cut off; when V < V0, control the first solenoid valve to conduct and the second solenoid valve to cut off, and when the real-time flow rate detected by the first flowmeter is V0 - V, control the first solenoid valve to cut off; or,
[0022] When the screw compressor includes a third flowmeter, a first solenoid valve, a second solenoid valve, a first check valve and a second check valve,
[0023] When V = V0, control the first solenoid valve and the second solenoid valve to be in a cut-off state; when V > V0, control the second solenoid valve to conduct and the first solenoid valve to cut off, and when the real-time flow rate detected by the third flowmeter is V - V0, control the second solenoid valve to cut off; when V < V0, control the first solenoid valve to conduct and the second solenoid valve to cut off, and when the real-time flow rate detected by the third flowmeter is V0 - V, control the first solenoid valve to cut off.
[0024] In some embodiments, the real-time pressure fluid volume V is the difference between the sum of the inlet flow rates detected by the first flowmeter each time and the sum of the outlet flow rates detected by the second flowmeter each time; or,
[0025] The real-time pressure fluid volume V is the difference between the sum of the inlet flow rates detected by the third flowmeter each time and the sum of the outlet flow rates detected each time.
[0026] A screw compressor and its control method provided by the present invention have the following beneficial effects:
[0027] By providing a pressurizing port and a pressure relief port on the second chamber, and controlling the pressure fluid regulating component to control the inflow and outflow of the pressure fluid in the second chamber, changing the position of the piston in the piston chamber, and then driving the slide valve to move to change the effective working length or pressure ratio of the screw rotor, realizing the load regulation or pressure ratio regulation of the screw compressor. In specific applications, the actual volume of the second chamber can be controlled by the amount of pressure fluid entering or flowing out of the second chamber, and then the position adjustment of the piston-slide valve can be realized, which is beneficial to simplifying the control logic of the screw compressor, reducing the complexity of the control process, and the adjustment is more timely and efficient. Description of the Drawings
[0028] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. The drawings in the following description are merely exemplary. For those of ordinary skill in the art, without creative efforts, other implementation drawings can also be obtained based on the provided drawings.
[0029] Figure 1 is a schematic structural diagram (simplified diagram) of some components in the pressure fluid control assembly and the adjustment assembly of a screw compressor in an embodiment of the present invention;
[0030] Figure 2 is Figure 1 a schematic diagram of the state when the first solenoid valve in [Figure number] is in the connected state and the second solenoid valve is in the cut-off state. The figure shows that the pressure fluid flows into the second chamber through the pressurizing port to increase the volume of the pressure fluid in the second chamber, thereby driving the piston and the slide valve to move to the left. In the figure, F1 is the axial (axial direction of the piston rod) resultant force of the pressure of the pressure fluid in the second chamber and the pressure of the compressed fluid borne by the left end face of the slide valve (if there is an elastic member, it also includes the elastic force of the elastic member);
[0031] Figure 3 is Figure 1 a schematic diagram of the state when the first solenoid valve in [Figure number] is in the cut-off state and the second solenoid valve is in the connected state. The figure shows that the pressure fluid flows out of the second chamber through the pressure relief port to reduce the volume of the pressure fluid in the second chamber, thereby driving the piston and the slide valve to move to the right. In the figure, F2 is the axial resultant force of the pressure of the pressure fluid in the second chamber and the pressure of the compressed fluid borne by the left end face of the slide valve (if there is an elastic member, it also includes the elastic force of the elastic member);
[0032] Figure 4 is a schematic structural diagram (simplified diagram) of some components in the pressure fluid control assembly and the adjustment assembly of a screw compressor in another embodiment of the present invention;
[0033] Figure 5 is Figure 4 a schematic diagram of the state when the first solenoid valve in [Figure number] is in the connected state and the second solenoid valve is in the cut-off state. The figure shows that the pressure fluid flows into the second chamber through the pressurizing port to increase the volume of the pressure fluid in the second chamber, thereby driving the piston and the slide valve to move to the left. In the figure, F1 is the axial (axial direction of the piston rod) resultant force of the pressure of the pressure fluid in the second chamber and the pressure of the compressed fluid borne by the left end face of the slide valve (if there is an elastic member, it also includes the elastic force of the elastic member);
[0034] Figure 6 is Figure 4Schematic diagram of the state when the first solenoid valve is in the cut-off state and the second solenoid valve is in the connected state. In the figure, it is shown that the pressure fluid flows out of the second chamber through the pressure relief port to reduce the volume of the pressure fluid in the second chamber, thereby driving the piston and the spool to move to the right. In the figure, F2 is the axial resultant force of the pressure of the pressure fluid in the second chamber and the compressed fluid borne by the left end face of the spool (if there is an elastic member, it also includes the elastic force of the elastic member).
[0035] The reference numerals are as follows:
[0036] 1. Piston; 11. Piston rod; 2. Piston chamber; 21. First chamber; 22. Second chamber; 221. Pressurizing port; 222. Pressure relief port; 31. Loading pipeline; 311. First flowmeter; 312. First solenoid valve; 32. Unloading pipeline; 321. Second flowmeter; 322. Second solenoid valve; 33. Third flowmeter; 341. First check valve; 342. Second check valve. Specific embodiments
[0037] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way constitutes a limitation to the present invention and its application or use. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0038] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the orientation words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description. Without contrary explanation, these orientation words do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the protection scope of the present invention; the orientation words "inside, outside" refer to the inside and outside of the contour of each component itself.
[0039] For ease of description, spatial relative terms such as "above", "over", "on the upper surface", "upper" etc. may be used herein to describe the spatial positional relationship of one device or feature to other devices or features as shown in the figures. It should be understood that the spatial relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, a device described as "above" or "over" other devices or structures will then be oriented "below" or "under" the other devices or structures. Thus, the exemplary term "above" can include both orientations of "above" and "below". The device may also be positioned in other different ways (rotated 90° or at other orientations), and the corresponding explanations are made for the spatial relative descriptions used herein.
[0040] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Without further statement, the above terms have no special meaning, and thus should not be construed as limiting the scope of protection of the present invention.
[0041] See Figure 1 and Figure 6As shown, according to an embodiment of the present invention, a screw compressor is provided, including a compressor body (not shown and not indexed in the figure). A compression chamber (not shown and not indexed in the figure) is formed inside the compressor body. A screw rotor (not shown and not indexed in the figure, which can be a single screw or a double screw) is arranged inside the compression chamber and is driven by a motor to rotate, thereby achieving the purpose of compressing fluid. The screw compressor further includes an adjustment assembly (not shown and not indexed in the figure) for adjusting the pressure ratio or capacity of the screw compressor. The adjustment assembly includes a slide valve (not shown and not indexed in the figure) and a piston 1 fixedly connected to the slide valve. That is to say, the movement of the slide valve is synchronized with that of the piston 1. It can be understood that the slide valve can serve as a part of the wall of the compression chamber. A piston chamber 2 is further formed inside the compressor body. The piston 1 is located inside the piston chamber 2 and divides the piston chamber 2 into an independent first chamber 21 and a second chamber 22. Among them, the second chamber 22 is located on the side of the first chamber 21 away from the slide valve. The second chamber 22 is configured with a pressure inlet 221 and a pressure outlet 222 communicating therewith. It further includes a pressure fluid control assembly (not shown and not indexed in the figure). The pressure fluid control assembly can be controlled to increase pressure fluid into the second chamber 22 via the pressure inlet 221 (that is, the pressure inlet 221 is used for flowing in pressure fluid) or reduce pressure fluid from the second chamber 22 via the pressure outlet 222 (that is, the pressure outlet 222 is used for flowing out pressure fluid), so as to drive the slide valve to move by adjusting the volume of the second chamber 22, thereby changing the effective working length of the screw rotor (that is, the length of the part where the slide valve and the screw rotor cooperate) or the pressure ratio of the screw rotor. The aforementioned pressure fluid can be lubricating oil, for example. It can be understood that for a compressor of the load adjustment type (that is, the capacity adjustment type), the effective working length of the screw rotor is specifically changed, while for a compressor of the pressure ratio adjustment type, the pressure ratio of the screw rotor is specifically changed.
[0042] In this technical solution, by providing a pressure inlet 221 and a pressure outlet 222 on the second chamber 22, the control of the inflow and outflow of the pressure fluid in the second chamber 22 is achieved through the control of the pressure fluid control assembly, so as to change the position of the piston 1 in the piston chamber 2, and then drive the slide valve to move to change the effective working length or the pressure ratio of the screw rotor, realizing the load adjustment or the pressure ratio adjustment of the screw compressor. In specific applications, the actual volume of the second chamber 22 can be changed by controlling the amount of the pressure fluid flowing into or out of the second chamber 22, thereby realizing the position adjustment of the piston-slide valve, which is beneficial to simplifying the control logic of the screw compressor, reducing the complexity of the control process, and enabling more timely and efficient adjustment.
[0043] For specific reference Figures 1 to 3As shown, in a specific embodiment, the pressure fluid regulation assembly includes a loading pipeline 31 controllably connected to the outlet (such as the oil supply port, not shown in the figure) of a pressure fluid source (such as a hydraulic oil pump), and an unloading pipeline 32 controllably connected to the return port of a pressure fluid unloading component (the aforementioned pressure fluid unloading component can be the oil phase of a hydraulic oil pump, and the corresponding return port is then the oil return port). A first flowmeter 311 is connected in series on the loading pipeline 31, and a second flowmeter 321 is connected in series on the unloading pipeline 32.
[0044] In this technical solution, by respectively connecting a first flowmeter 311 and a second flowmeter 321 in series on the loading pipeline 31 and the unloading pipeline 32, the pressure fluid entering and flowing out of the second chamber 22 can be recorded in real time. Furthermore, the accurate volume of the pressure fluid in the second chamber 22 can be obtained by taking the difference between the total flow rates of the pressure fluid recorded by the two flowmeters. Then, the accurate position of the piston 1, that is, the relative position between the spool valve and the screw rotor, can be obtained through the piston diameter or the piston chamber diameter. In this way, the compression ratio state or load state of the screw compressor can be adjusted efficiently and timely, without the need to repeatedly iterate the compression ratio or flow rate multiple times and then convert it into digital control of the lubricating oil flow rate in the compression oil cylinder as in the prior art, and the control is simpler.
[0045] In some embodiments, a first solenoid valve 312 is also connected in series on the loading pipeline 31, and a second solenoid valve 322 is also connected in series on the unloading pipeline 32. The specific installation positions of the first solenoid valve 312 and the second solenoid valve 322 are not particularly limited, and it is preferably close to the second chamber 22, for example, it can be assembled on the outer wall surface of the second chamber 22.
[0046] In this technical solution, by respectively arranging a first solenoid valve 312 and a second solenoid valve 322 on the loading pipeline 31 and the unloading pipeline 32, the component integration degree and structural compactness of the device can be improved.
[0047] Specifically refer to Figures 4 to 6 As shown, in another specific embodiment, the pressure fluid regulation assembly includes a loading pipeline 31 controllably connected to the outlet of a pressure fluid source and an unloading pipeline 32 controllably connected to the return port of a pressure fluid unloading component. The loading pipeline 31 and the unloading pipeline 32 share a third flowmeter 33. At this time, it can be understood that while the third flowmeter 33 records the flow rate, the corresponding control system also needs to independently record the flow rates corresponding to loading (inflow) and unloading (return flow) of the third flowmeter 33, so as to obtain the accurate volume of the pressure fluid in the second chamber 22 by taking the difference between the total loading flow rate and the total unloading flow rate.
[0048] In this technical solution, the loading pipeline 31 and the unloading pipeline 32 share a third flow meter 33, which can reduce the number of flow meters used, and at the same time reduce the manufacturing cost, it can also reduce the number of failure points of the equipment.
[0049] In some embodiments, the third flowmeter 33 is connected in series to the loading pipeline 31 and divides the loading pipeline 31 into a loading downstream pipe section (not labeled in the figure) connected to the pressurization port 221 and a loading upstream pipe section (not labeled in the figure) connected to the outlet and capable of controllable opening and closing. The unloading pipeline 32 has an unloading upstream pipe section (not labeled in the figure) connected to the loading upstream pipe section and capable of controllable opening and closing, and an unloading downstream pipe section (not labeled in the figure) connected between the third flowmeter 33 and the reflux port. A first solenoid valve 312 is connected in series to the loading upstream pipe section, and a second solenoid valve 322 is connected in series to the unloading downstream pipe section.
[0050] In this technical solution, the first solenoid valve 312 is set in the upstream pipe section of loading, and the second solenoid valve 322 is set in the downstream pipe section of unloading. On the premise that the loading pipeline 31 and the unloading pipeline 32 share the third flow meter 33, independent control of the inflow and reflux of the second chamber 22 is guaranteed.
[0051] In some embodiments, the unloading upstream pipe section is connected to the loading upstream pipe section at a first position (not marked in the figure), and a first one-way valve 341 is connected in series on the loading upstream pipe section between the first position and the outlet, and the first one-way valve 341 is connected in series from the outlet to the pressurizing port 221 and is blocked in the reverse direction, and a second one-way valve 342 is connected in series on the unloading upstream pipe section, and the second one-way valve 342 is connected in series from the pressure relief port 222 to the third flowmeter 33 and is blocked in the reverse direction.
[0052] In this technical solution, by connecting the first one-way valve 341 and the second one-way valve 342 in series on the loading upstream pipe section and the unloading upstream pipe section respectively, the pressure fluid control component only needs to control the on and off of the first solenoid valve 312 and the second solenoid valve 322 to achieve the inlet and reflux control under the premise of sharing the third flow meter 33, which simplifies the component layout and the pipeline design, making the control simpler.
[0053] In some embodiments, the piston 1 and the sliding valve are fixedly connected as a whole via a piston rod 11. An elastic member (not shown in the figure) is also provided in the first chamber 21. The elastic member is sleeved on the piston rod 11 and clamped between the end surface of the piston 1 facing away from the second chamber 22 and the inner wall surface of the first chamber 21. The elastic member can specifically be a coil spring.
[0054] In this technical solution, by arranging an elastic member on the piston rod 11, force can be applied to the piston 1 when the equipment stops abnormally so that the piston 1 can return to its initial position, that is, a state where there is no pressure flowing in the second chamber 22 (the volume of the second chamber 22 is 0 at this time).
[0055] According to an embodiment of the present invention, there is also provided a control method for the screw compressor as described above, comprising the following steps:
[0056] Obtaining a target operating condition of the screw compressor, and obtaining a target pressure fluid volume V0 of the second chamber 22 corresponding to the target operating condition according to the target operating condition. It can be understood that different target operating conditions correspond to different aforementioned target pressure fluid volumes V0, and the specific corresponding relationship can be clearly determined by design calculation;
[0057] Obtaining the real-time pressure fluid volume V of the second chamber 22, specifically, the real-time pressure fluid volume V is the difference between the sum of the inflow flow rates detected by the first flow meter 311 and the sum of the outflow flow rates detected by the second flow meter 321, or the real-time pressure fluid volume V is the difference between the sum of the inflow flow rates detected by the third flow meter 33 and the sum of the outflow flow rates detected;
[0058] The relationship between the real-time pressure fluid volume V and the target pressure fluid volume V0 is determined to control whether the pressure fluid regulating component adds pressure fluid to the second chamber 22 (that is, controls the pressure fluid to flow into the second chamber 22) or reduces pressure fluid from the second chamber 22 (that is, controls the pressure fluid to flow out of the second chamber 22). In this process, the pressure fluid flowing through it is detected in real time by the first flow meter 311, the second flow meter 321 or the third flow meter 33, and the inflow or outflow is controlled to be stopped after it is detected that the inflow or outflow pressure fluid reaches the target flow rate.
[0059] Specifically, determining the magnitude relationship between the real-time pressure fluid volume V and the target pressure fluid volume V0 to control whether the pressure fluid control component adds pressure fluid to the second chamber 22 or reduces pressure fluid from the second chamber 22 specifically includes:
[0060] When V=V0, the pressure fluid regulating component is controlled to neither add pressure fluid to the second chamber 22 nor reduce pressure fluid from the second chamber 22 so that the position of the slide valve remains unchanged; or,
[0061] When V > V0, control the pressure fluid regulation component to reduce the pressure fluid in the second chamber 22, so that the spool slides close to the second chamber 22 to reduce the effective working length or pressure ratio of the screw rotor until V = V0, then stop reducing the pressure fluid; or,
[0062] When V < V0, control the pressure fluid regulation component to increase the pressure fluid into the second chamber 22, so that the spool slides away from the second chamber 22 to increase the effective working length or pressure ratio of the screw rotor until V = V0, then stop increasing the pressure fluid.
[0063] In some embodiments, when the screw compressor includes a first flowmeter 311, a second flowmeter 321, a first solenoid valve 312 and a second solenoid valve 322,
[0064] When V = V0, control the first solenoid valve 312 and the second solenoid valve 322 to be in a cut-off state; when V > V0, control the second solenoid valve 322 to conduct and the first solenoid valve 312 to cut off, and when the real-time flow rate detected by the second flowmeter 321 is V - V0, control the second solenoid valve 322 to cut off. At this time, with Figure 1 the shown orientation as a reference, the piston 1 will slide from left to right under the action of the pressure difference on both sides (as shown in Figure 3 and Figure 6 shown); when V < V0, control the first solenoid valve 312 to conduct and the second solenoid valve 322 to cut off, and when the real-time flow rate detected by the first flowmeter 311 is V0 - V, control the first solenoid valve 312 to cut off. At this time, with Figure 1 the shown orientation as a reference, the piston 1 will slide from right to left under the action of the pressure difference on both sides (as shown in Figure 2 and Figure 5 shown); or,
[0065] When the screw compressor includes a third flowmeter 33, a first solenoid valve 312, a second solenoid valve 322, a first one-way valve 341 and a second one-way valve 342, when V = V0, control the first solenoid valve 312 and the second solenoid valve 322 to be in a cut-off state; when V > V0, control the second solenoid valve 322 to conduct and the first solenoid valve 312 to cut off, and when the real-time flow rate detected by the third flowmeter 33 is V - V0, control the second solenoid valve 322 to cut off; when V < V0, control the first solenoid valve 312 to conduct and the second solenoid valve 322 to cut off, and when the real-time flow rate detected by the third flowmeter 33 is V0 - V, control the first solenoid valve 312 to cut off.
[0066] For example, if it is pressure ratio adjustment, the current pressure ratio is 3.0 (i.e., the current operating condition is a pressure ratio of 3.0), and the volume of oil in the corresponding oil cylinder (i.e., the volume in the aforementioned second chamber 22) is V = 1.5 L (this volume is also the current pressure fluid volume V0 corresponding to a pressure ratio of 3.0). Now, if you want to adjust the pressure ratio to 2.4, the corresponding target pressure fluid volume is V0 = 1.8 L. At this time, V0 > V, which means that 0.3 L of oil needs to be added to the oil cylinder. Drive the piston 1 to move along the direction away from the second chamber 22 (which can be defined as moving left) to a specified distance. During this process, the first flowmeter 311 is used to detect the pressure fluid flowing into the second chamber 22 in real time until 0.3 L of lubricating oil is filled and the oil supply stops.
[0067] It should be noted that when the compressor is initially designed, whether it is pressure ratio adjustment or capacity adjustment, the volume of lubricating oil (i.e., the aforementioned pressure fluid) that can be accommodated in the oil cylinder (i.e., the aforementioned second chamber 22, the same below) corresponding to the movement of the slide valve has been calculated and formed into a database, which is incorporated into the overall machine control logic. For example, when the pressure ratio is 3.0, the volume V of lubricating oil that the oil cylinder can accommodate 3.0 (The specific value is reasonably determined according to the actual piston chamber diameter, etc.); when the load is 75%, the volume V of lubricating oil that the oil cylinder can accommodate 75％ . In this way, different types of databases can be formed. During the operation of the overall machine, the known data in the control logic can be called at any time for comparison (i.e., a one-to-one correspondence between the target operating condition and the target pressure fluid volume V0 is formed).
[0068] Taking Figures 1 to 3 the shown embodiment as an example, in a certain operating state of the overall machine, the volume data V11, V12, V13,..., V1n and V21, V22, V23,..., V2n of each loading and unloading of the two flowmeters Q1 (corresponding to the first flowmeter) and Q2 (corresponding to the second flowmeter) on the compressor loading and unloading oil path since the operation can be obtained from the overall machine control logic. The cumulative volumes V1 = V11 + V12 + V13 +... + V1n and V2 = V21 + V22 + V23 +... + V2n of the two flowmeters can be calculated. Furthermore, the volume V of lubricating oil in the oil cylinder in the current state can be calculated as V = V1 - V2, where V1 is the sum of V11, V12, V13,..., V1n, and V2 is the sum of V21, V22, V23,..., V2n.
[0069] If it is necessary to run to a certain target operating condition, and the volume of lubricating oil in the corresponding oil cylinder is V0, the overall machine control logic will calculate the difference △V between V0 and V, and control the opening or closing of the solenoid valves (i.e., the aforementioned first solenoid valve and second solenoid valve, the same below) according to the difference △V to achieve oil supply or oil discharge, so as to reach the specified volume V0. If V < V0, the compressor will receive the overall machine control instruction, open the loading solenoid valve (i.e., the aforementioned first solenoid valve 312, the same below), and close the unloading solenoid valve (i.e., the aforementioned second solenoid valve 322, the same below). Under the action of the pressure difference, the slide valve and the oil piston will move to the left side in the figure as shown, and the moving distance is controlled by the flow meter Q1. When the specified flow rate △V is reached, the loading solenoid valve is closed and the operation is maintained. Similarly, if V > V0, the compressor will receive the overall machine control instruction, open the unloading solenoid valve, and close the loading solenoid valve. Under the action of the pressure difference, the slide valve and the oil piston will move to the right side in the figure as shown, and the moving distance is controlled by the flow meter Q2. When the specified flow rate △V is reached, the unloading solenoid valve is closed and the operation is maintained.
[0070] In this technical solution, by connecting the first flow meter 311 and the second flow meter 321 in series on the loading pipeline 31 and the unloading pipeline 32 respectively, the pressure fluid entering and flowing out of the second chamber 22 can be recorded in real time. Furthermore, the accurate volume of the pressure fluid in the second chamber 22 can be obtained by taking the difference between the total flow rates of the pressure fluid recorded by the two flow meters. Then, the accurate position of the piston 1, that is, the relative position between the slide valve and the screw rotor, can be obtained through the piston diameter or the piston chamber diameter. In this way, the compression ratio state or the load state of the screw compressor can be adjusted efficiently and in a timely manner, without the need for repeated iterations of the compression ratio or flow rate as in the prior art and then converting it into digital control of the lubricating oil flow rate in the compressor oil cylinder. The control is simpler, and it can effectively prevent the problems of energy efficiency and load fluctuations that occur during the slide valve adjustment of the compressor due to control delay.
[0071] The first flow meter 311, the second flow meter 321 and the third flow meter 33 of the present invention can all be conventional commercially available components. Preferably, a flow meter configured with a functional module capable of converting the real-time calculation of the flow rate into volume is used. Of course, the aforementioned conversion can also be achieved by using the relevant functional modules in the control module of the compressor.
[0072] It is easy for those skilled in the art to understand that, on the premise of no conflict, the advantageous technical features of the above various methods can be freely combined and superimposed.
[0073] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention. The above is only the preferred implementation manner of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and variations can be made, and these improvements and variations should also be regarded as within the protection scope of the present invention.
Claims
1. A screw compressor, characterized in that, It includes a compressor body, a compression chamber is formed in the compressor body, a screw rotor is provided in the compression chamber, and it further includes an adjustment assembly for adjusting the pressure ratio or capacity of the screw compressor. The adjustment assembly includes a slide valve and a piston (1) fixedly connected to the slide valve. A piston chamber (2) is further formed in the compressor body. The piston (1) is located in the piston chamber (2) and divides the piston chamber (2) into an independent first chamber (21) and a second chamber (22). Among them, the second chamber (22) is on the side of the first chamber (21) away from the slide valve. The second chamber (22) is configured with a pressurizing port (221) and a pressure relief port (222) communicated therewith. It further includes a pressure fluid control assembly, and the pressure fluid control assembly can be controlled to increase pressure fluid into the second chamber (22) via the pressurizing port (221) or reduce pressure fluid from the second chamber (22) via the pressure relief port (222) to drive the slide valve to move by adjusting the volume of the second chamber (22), thereby changing the effective working length of the screw rotor or the pressure ratio of the screw rotor.
2. The screw compressor according to claim 1, wherein, The pressure fluid control assembly includes a loading pipeline (31) controllably communicated with the outlet of the pressure fluid source and an unloading pipeline (32) controllably communicated with the return port of the pressure fluid unloading component. A first flowmeter (311) is connected in series on the loading pipeline (31), and a second flowmeter (321) is connected in series on the unloading pipeline (32).
3. The screw compressor according to claim 2, characterized in that, A first solenoid valve (312) is further connected in series on the loading pipeline (31), and a second solenoid valve (322) is further connected in series on the unloading pipeline (32).
4. The screw compressor according to claim 1, characterized in that, The pressure fluid control assembly includes a loading pipeline (31) controllably communicated with the outlet of the pressure fluid source and an unloading pipeline (32) controllably communicated with the return port of the pressure fluid unloading component. The loading pipeline (31) and the unloading pipeline (32) share a third flowmeter (33).
5. The screw compressor according to claim 4, characterized in that, The third flowmeter (33) is connected in series on the loading pipeline (31) and divides the loading pipeline (31) into a loading downstream pipe section connected to the pressurizing port (221) and a loading upstream pipe section connected to the outlet and capable of being controllably switched on and off. The unloading pipeline (32) has an unloading upstream pipe section communicated with the loading upstream pipe section and capable of being controllably switched on and off and an unloading downstream pipe section connected between the third flowmeter (33) and the return port. A first solenoid valve (312) is connected in series on the loading upstream pipe section, and a second solenoid valve (322) is connected in series on the unloading downstream pipe section.
6. The screw compressor according to claim 5, wherein The unloading upstream pipe section is connected to the loading upstream pipe section at a first position. A first one-way valve (341) is connected in series to the loading upstream pipe section between the first position and the outlet. The first one-way valve (341) is connected in series from the outlet to the pressurizing port (221) and is blocked in the reverse direction. A second one-way valve (342) is connected in series to the unloading upstream pipe section. The second one-way valve (342) is connected in series from the pressure relief port (222) to the third flow meter (33) and is blocked in the reverse direction.
7. The screw compressor according to any one of claims 1 to 6, characterized in that, The piston (1) and the sliding valve are fixedly connected as a whole via a piston rod (11); an elastic member is also provided in the first chamber (21); the elastic member is sleeved on the piston rod (11) and clamped between an end surface of the piston (1) facing away from the second chamber (22) and an inner wall surface of the first chamber (21).
8. A control method for a screw compressor according to any one of claims 1 to 7, characterized in that, The steps include: Acquiring a target operating condition of the screw compressor, and acquiring a target pressure fluid volume V0 of the second chamber (22) corresponding to the target operating condition according to the target operating condition; Obtaining the real-time pressure fluid volume V of the second chamber (22); The relationship between the real-time pressure fluid volume V and the target pressure fluid volume V0 is determined to control whether the pressure fluid regulating component adds pressure fluid to the second chamber (22) or reduces pressure fluid from the second chamber (22).
9. The control method according to claim 8, wherein Determining the relationship between the real-time pressure fluid volume V and the target pressure fluid volume V0 and controlling whether the pressure fluid regulating component adds pressure fluid to the second chamber (22) or reduces pressure fluid from the second chamber (22) specifically includes: When V=V0, the pressure fluid regulating component is controlled to neither add pressure fluid to the second chamber (22) nor reduce pressure fluid from the second chamber (22) so that the position of the slide valve remains unchanged; or, When V>V0, the pressure fluid control component is controlled to reduce the pressure fluid from the second chamber (22), so that the slide valve slides close to the second chamber (22) to reduce the effective working length or pressure ratio of the screw rotor, until the pressure fluid is stopped from being reduced when V=V0; or, When V<V0, the pressure fluid regulating component is controlled to increase the pressure fluid into the second chamber (22) so that the slide valve slides away from the second chamber (22) to increase the effective working length or pressure ratio of the screw rotor, until the pressure fluid is stopped from being increased when V=V0.
10. The control method according to claim 9, wherein When the screw compressor includes a first flow meter (311), a second flow meter (321), a first solenoid valve (312) and a second solenoid valve (322), When V = V0, control the first solenoid valve (312) and the second solenoid valve (322) to be in a cut-off state; when V > V0, control the second solenoid valve (322) to conduct and the first solenoid valve (312) to cut off, and when the real-time flow rate detected by the second flowmeter (321) is V - V0, control the second solenoid valve (322) to cut off; when V < V0, control the first solenoid valve (312) to conduct and the second solenoid valve (322) to cut off, and when the real-time flow rate detected by the first flowmeter (311) is V0 - V, control the first solenoid valve (312) to cut off; or, When the screw compressor includes a third flowmeter (33), a first solenoid valve (312), a second solenoid valve (322), a first check valve (341) and a second check valve (342), When V = V0, control the first solenoid valve (312) and the second solenoid valve (322) to be in a cut-off state; when V > V0, control the second solenoid valve (322) to conduct and the first solenoid valve (312) to cut off, and when the real-time flow rate detected by the third flowmeter (33) is V - V0, control the second solenoid valve (322) to cut off; when V < V0, control the first solenoid valve (312) to conduct and the second solenoid valve (322) to cut off, and when the real-time flow rate detected by the third flowmeter (33) is V0 - V, control the first solenoid valve (312) to cut off.
11. The control method according to claim 10, wherein The real-time pressure fluid volume V is the difference between the sum of the inflow flow rates detected by the first flowmeter (311) each time and the sum of the outflow flow rates detected by the second flowmeter (321) each time; Or, The real-time pressure fluid volume V is the difference between the sum of the inflow flow rates detected by the third flowmeter (33) each time and the sum of the outflow flow rates detected each time.