Ultra-wide working condition multi-stage time-sharing series-parallel centrifugal vacuum pump system

Abstract

The application discloses a kind of ultra-wide working condition multistage time-sharing series-parallel centrifugal vacuum pump systems applied to vacuum pump related field, by setting up one-stage vacuum pump unit and two, three-stage centrifugal vacuum pumps in parallel or in series, and cooperate with multiple switching valves, realize one-stage unit separate operation, two three-stage unit separate operation, parallel and series four kinds of time-sharing switching operation mode, so that system can cover from low vacuum degree high flow to high vacuum degree low flow Ultra-wide working condition range, significantly widen stable working interval, increase surge margin;In addition, by setting buffer tank containing laminated pressure relief assembly at each key pipeline node and setting precision regulating valve in air inlet pipeline, adaptive pressure relief or air supply can be carried out when mode switching or air flow mutation, effectively suppresses pressure fluctuation peak, overcomes "air rush" and transient pressure impact problem, so as to ensure the efficiency and stability of system in ultra-wide working condition and long time-varying working condition operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of vacuum pumps, in particular to a multi-stage time-sharing series-parallel centrifugal vacuum pump system with ultra-wide working conditions. BACKGROUND

[0002] In the system design of centrifugal vacuum pumps, the traditional multi-stage pure series mode can improve the system pressure ratio, but it will narrow the stable working flow range and increase the risk of surge; while the multi-stage pure parallel mode can widen the flow range, but it cannot improve the system pressure ratio, and is prone to cause uneven gas distribution such as 'gas stealing', affecting stability.

[0003] The centrifugal vacuum pump group for large flow and low pressure disclosed in Chinese patent CN120231764B aims to meet the requirements of large flow and high compression ratio, but its multi-stage series structure still cannot avoid the inherent disadvantage that the stable working range decreases with the increase of the number of stages.

[0004] In view of the surge problem prone to occur in series operation, Chinese patent CN111828367A discloses a surge protection device and method for a high-speed centrifugal vacuum pump, which prevents surge and backflow through valve group control, pressure monitoring and check valve. However, this scheme mainly focuses on safety protection and does not solve the fundamental problem of efficient and stable operation of series-parallel combined system in wide pressure ratio and wide flow range, and the transient pressure impact caused by the sharp change of gas momentum in the series-parallel switching process may threaten the safety of the pump group.

[0005] Therefore, for scientific experimental research projects such as hypersonic wind tunnels that require wide pressure ratio range (1-36 or higher), wide flow range and long time-varying working condition operation, the traditional multi-stage pure series and multi-stage pure parallel combination of centrifugal vacuum pumps cannot meet the above ultra-wide working condition and long time-varying working condition operation requirements.

[0006] Therefore, it is urgent to provide a multi-stage time-sharing series-parallel centrifugal vacuum pump system with ultra-wide working conditions, which can effectively overcome the defect that the stability decreases with the increase of the number of stages. SUMMARY

[0007] 1. Technical problem to be solved

[0008] The core of the present application is to effectively solve the problem of decreasing stability with increasing number of stages in the prior art by using a multi-stage vacuum pump system with switchable series-parallel operation mode; and under the action of the buffer tank, the pressure can be automatically released according to the actual situation of the gas pressure under different working conditions.

[0009] 2. Technical scheme

[0010] To solve the above problems, the present application adopts the following technical scheme.

[0011] The system comprises a flow pipe, a first-stage inlet pipe fixedly connected with the flow pipe, a three-way distribution pipe fixedly connected with the middle part of the first-stage inlet pipe, a first-stage vacuum pump unit connected with the three-way distribution pipe, a second-stage centrifugal vacuum pump, a third-stage centrifugal vacuum pump, and two frequency conversion units; a third-stage inlet pipe is fixedly connected between the exhaust end of the second-stage centrifugal vacuum pump and the inlet end of the third-stage centrifugal vacuum pump; the first-stage vacuum pump unit comprises two first-stage centrifugal vacuum pumps; a second-stage inlet pipe is fixedly connected between the tail end of the first-stage inlet pipe and the air inlet of the second-stage centrifugal vacuum pump, and a front parallel switch valve is installed at the connection position; the air inlets of the two first-stage centrifugal vacuum pumps are fixedly connected with two exhaust ends of the three-way distribution pipe; a first-stage inlet switch valve is fixedly installed at the air inlet end of the three-way distribution pipe; the exhaust ends of the two first-stage centrifugal vacuum pumps are fixedly connected with a first-stage exhaust pipe; one end of the first-stage exhaust pipe is fixedly connected with a converging exhaust pipe; a third-stage exhaust pipe is fixedly connected between the exhaust end of the third-stage centrifugal vacuum pump and the converging exhaust pipe; the other end of the first-stage exhaust pipe is fixedly connected with the outer end of the second-stage inlet pipe; a first-stage exhaust parallel switch valve is fixedly installed at the outer end of the first-stage exhaust pipe close to the converging exhaust pipe; a series switch valve is fixedly installed at the outer end of the first-stage exhaust pipe close to the second-stage inlet pipe; a gas supplement pipe is fixedly connected with the outer end of the first-stage exhaust pipe; a plurality of precision adjusting valves are fixedly installed at the outer ends of the flow pipe and the gas supplement pipe; the gas supplement pipe is located between a cooler and the series switch valve; the first-stage exhaust parallel switch valve and the series switch valve are respectively located outside the exhaust ports of the two first-stage centrifugal vacuum pumps; a cooler is connected in series with the flow pipe, one end of the first-stage exhaust pipe away from the converging exhaust pipe, and the third-stage inlet pipe; and a quick stop valve is installed on the converging exhaust pipe.

[0012] A buffer tank is connected in series with the outer ends of the two arms of the three-way distribution pipe, the outer end of the second-stage inlet pipe close to the second-stage centrifugal vacuum pump, the outer end of the third-stage inlet pipe close to the third-stage centrifugal vacuum pump, and the converging exhaust pipe; the buffer tank on the converging exhaust pipe is located between the tail end of a double-flow pressure relief plate and the quick stop valve; a laminated pressure relief assembly is fixedly installed inside the buffer tank; the laminated pressure relief assembly comprises a plurality of double-flow pressure relief plates, a plurality of taper surface pressure relief cylinders fixedly connected between the air inlets of the buffer tank and adjacent double-flow pressure relief plates, and between adjacent two double-flow pressure relief plates; and a plurality of connecting blocks are fixedly connected between the outer ends of the double-flow pressure relief plates and the inner wall of the buffer tank.

[0013] Further, the frequency conversion unit comprises a double-shaft frequency conversion motor, and two gearboxes connected with the two output shafts of the double-shaft frequency conversion motor; the two first-stage centrifugal vacuum pumps share one frequency conversion unit; and the second-stage centrifugal vacuum pump and the third-stage centrifugal vacuum pump share one frequency conversion unit.

[0014] Further, the multiple conical relief cylinders and the double-flow relief plates are sequentially communicated, and the last double-flow relief plate is opposite to the exhaust port of the buffer tank and directly communicates with the inside of the buffer tank along the direction of air movement.

[0015] Further, the exhaust side port of the relief straight hole communicates with the next conical relief cylinder, the exhaust side port of the L-shaped exhaust hole directly communicates with the inside of the buffer tank, and the double-flow relief plate is fixedly connected with a flow limiting ring near the air inlet side end of the buffer tank.

[0016] Further, the double-flow relief plate is drilled with multiple relief straight holes arranged in a ring array, and is drilled with multiple L-shaped exhaust holes arranged in a ring array, the L-shaped exhaust hole array, the relief straight hole array and the flow limiting ring are coaxially arranged and sequentially arranged away from the axis, and the multiple L-shaped exhaust holes and the relief straight holes are staggered.

[0017] Further, the conical relief cylinder comprises a conical ring piece fixedly connected with the radial inner wall of the buffer tank or the end surface of the double-flow relief plate towards the air inlet end of the buffer tank, multiple split rings arranged in a ring array in sliding connection with the other end surface of the double-flow relief plate, and multiple path modification assemblies fixedly connected with the middle parts of the multiple split rings, the outer end middle part of the conical ring piece is further fixedly connected with an outer sealing layer, the outer sealing layer is attached to the surface of the double-flow relief plate and the connecting block, and the end of the outer sealing layer away from the conical ring piece crosses the flow limiting ring and is fixedly connected with the outer wall of the flow limiting ring, and the outer sealing layer is made of a flexible sealing material.

[0018] Optionally, the end parts of the multiple split rings close to each other are drilled with accommodating grooves, and the adjacent two accommodating grooves are fixedly connected with a reset elastic strip, the reset elastic strip is made of an elastic material, and when the two split rings contact each other, the reset elastic strip is in a straightened state.

[0019] Further, the path modification assembly comprises a sealing plate and a connecting rod fixedly connected between the sealing plate and the middle part of the inner wall of the split ring, and when the split ring contacts the flow limiting ring, the sealing plate completely covers the L-shaped exhaust hole.

[0020] 3. Advantages

[0021] Compared with the prior art, the advantages of the present application are:

[0022] (1) By setting the first-stage vacuum pump unit and the second-stage and third-stage centrifugal vacuum pumps in parallel or series, and cooperating with multiple switching valves, four time-sharing switching operation modes of single first-stage unit operation, single second-stage and third-stage unit operation, parallel connection and series connection are realized, so that the system can cover an ultra-wide working condition range from low vacuum degree high flow to high vacuum degree low flow, significantly widening the stable working interval and increasing the surge margin.

[0023] (2) In addition, by setting a buffer tank containing a laminated pressure relief assembly at each key pipeline node and a precision regulating valve at the intake pipeline, adaptive pressure relief or air supplement can be performed when mode switching or air flow mutation occurs, effectively suppressing the pressure fluctuation peak, overcoming the "air stealing" and transient pressure impact problems, thereby ensuring the efficiency and stability of the system in ultra-wide operating conditions and long-time varying operating conditions. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a right side perspective view of the present application;

[0025] Figure 2 is a left side perspective view of the present application;

[0026] Figure 3 is a perspective view of a primary vacuum pump unit of the present application;

[0027] Figure 4 is a perspective view of a secondary centrifugal vacuum pump and a tertiary centrifugal vacuum pump of the present application;

[0028] Figure 5 is a schematic diagram when the primary vacuum pump unit of the present application operates alone;

[0029] Figure 6 is a schematic diagram when the secondary and tertiary centrifugal vacuum pumps of the present application operate alone;

[0030] Figure 7 is a schematic diagram when the primary vacuum pump unit and the secondary and tertiary centrifugal vacuum pumps of the present application operate in parallel;

[0031] Figure 8 is a schematic diagram when the primary vacuum pump unit and the secondary and tertiary centrifugal vacuum pumps of the present application operate in series;

[0032] Figure 9 is a perspective view when the buffer tank of the present application is added;

[0033] Figure 10 is a top view schematic diagram when the buffer tank of the present application is added;

[0034] Figure 11 is a perspective view when the buffer tank of the present application is added;

[0035] Figure 12 is a front view cross-sectional schematic diagram when the buffer tank of the present application is relieved;

[0036] Figure 13 is a radial cross-sectional schematic diagram of the buffer tank of the present application;

[0037] Figure 14 is a radial cross-sectional schematic diagram when the buffer tank of the present application is relieved;

[0038] Figure 15 The variation process diagram of the conical relief cylinder in the pressure stabilizing process of the application.

[0039] Explanation of the reference numerals in the drawings:

[0040] 101 incoming pipe, 102 first-stage inlet pipe, 103 three-way distribution pipe, 104 first-stage exhaust pipe, 105 second-stage inlet pipe, 106 third-stage inlet pipe, 107 third-stage exhaust pipe, 108 exhaust pipe, 109 air supplement pipe, 21 first-stage centrifugal vacuum pump, 22 double-shaft variable frequency motor, 23 gear box, 3 cooler, 41 second-stage centrifugal vacuum pump, 42 third-stage centrifugal vacuum pump, 501 first-stage inlet switching valve, 502 first-stage exhaust parallel switching valve, 503 series switching valve, 504 preposition parallel switching valve;

[0041] 6 buffer tank, 7 double-channel relief plate, 71 connecting block, 72 flow-limiting ring, 701 L-shaped exhaust hole, 702 relief straight hole, 8 conical relief cylinder, 81 split ring, 821 sealing plate, 822 connecting rod, 83 conical ring piece, 84 outer sealing layer, 85 reset spring. DETAILED DESCRIPTION

[0042] The technical solutions will be described clearly and completely below in combination with the drawings in the embodiments of the application.

[0043] Embodiment 1

[0044] Please refer to Figures 1-2 A super-wide working condition multi-stage time-sharing series-parallel centrifugal vacuum pump system, comprising an incoming pipe 101, a first-stage inlet pipe 102 fixedly connected with the incoming pipe 101, a three-way distribution pipe 103 fixedly connected with the middle part of the first-stage inlet pipe 102, a first-stage vacuum pump unit connected with the three-way distribution pipe 103, a second-stage centrifugal vacuum pump 41, a third-stage centrifugal vacuum pump 42 and two variable frequency motor units, such as Figures 3-4 The exhaust end of the second-stage centrifugal vacuum pump 41 and the inlet end of the third-stage centrifugal vacuum pump 42 are fixedly connected with a third-stage inlet pipe 106, the first-stage vacuum pump unit comprises two first-stage centrifugal vacuum pumps 21, the variable frequency motor unit comprises a double-shaft variable frequency motor 22, two gear boxes 23 respectively connected with the two output shafts of the double-shaft variable frequency motor 22, and the two first-stage centrifugal vacuum pumps 21 share one variable frequency motor unit, and the second-stage centrifugal vacuum pump 41 and the third-stage centrifugal vacuum pump 42 share one variable frequency motor unit.

[0045] The end of the primary inlet pipe 102 is fixedly connected with the gas inlet of the secondary centrifugal vacuum pump, and a front parallel switch valve 504 is installed at the connection position. The gas inlets of the two primary centrifugal vacuum pumps 21 are fixedly connected with the two gas outlets of the three-way shunt pipe 103, and a primary inlet switch valve 501 is fixedly installed at the gas inlet of the three-way shunt pipe 103. The gas outlets of the two primary centrifugal vacuum pumps 21 are fixedly connected with the primary exhaust pipe 104. One end of the primary exhaust pipe 104 is fixedly connected with the converging exhaust pipe 108. The gas outlet of the tertiary centrifugal vacuum pump 42 is fixedly connected with the converging exhaust pipe 108 through a tertiary exhaust pipe 107. The other end of the primary exhaust pipe 104 is fixedly connected with the secondary inlet pipe 105. A primary exhaust parallel switch valve 502 is fixedly installed at the outer end of the primary exhaust pipe 104 close to the converging exhaust pipe 108. A series switch valve 503 is fixedly installed at the outer end of the primary exhaust pipe 104 close to the secondary inlet pipe 105. A gas supplement pipe 109 is fixedly connected with the outer end of the primary exhaust pipe 104. The gas supplement pipe 109 is located between the series switch valve 503 and the cooler 3. A plurality of precision adjusting valves are fixedly installed on the outer ends of the gas flow pipe 101 and the gas supplement pipe 109. When the gas pressure of the system suddenly drops, the precision adjusting valves on the gas flow pipe 101 and the gas supplement pipe 109 can be opened to supplement the gas, so as to compensate for the problem of sudden drop of gas pressure, reduce the lower limit of gas pressure fluctuation in actual operation, and improve the stability. The gas supplement pipe 109 is located between the cooler 3 and the series switch valve 503. The primary exhaust parallel switch valve 502 and the series switch valve 503 are located outside the gas outlets of the two primary centrifugal vacuum pumps 21. The gas flow pipe 101, the primary exhaust pipe 104 away from the converging exhaust pipe 108, and the tertiary inlet pipe 106 are all connected with the cooler 3 in series. The cooler 3 can pre-cool the gas entering the primary centrifugal vacuum pump 21, the secondary centrifugal vacuum pump 41, or the tertiary centrifugal vacuum pump 42, so that the temperature of the gas will not be too high when entering the primary centrifugal vacuum pump 21, the secondary centrifugal vacuum pump 41, or the tertiary centrifugal vacuum pump 42. A quick cut-off valve is also installed on the converging exhaust pipe 108.

[0046] The system has multiple different operation modes, which are as follows:

[0047] For example, Figure 5 When the primary vacuum pump unit is independently debugged and operated, the primary inlet switch valve 501 and the primary exhaust parallel switch valve 502 are opened, and the series switch valve 503 and the front parallel switch valve 504 are closed, so that the gas flow passes through the primary inlet switch valve 501 and the three-way shunt pipe 103 to enter the two primary centrifugal vacuum pumps 21. The exhaust gas of the two primary centrifugal vacuum pumps 21 is combined in the primary exhaust pipe 104 and then passes through the primary exhaust parallel switch valve 502 to enter the converging exhaust pipe 108 and is discharged.

[0048] For example, Figure 6When the two-stage and three-stage centrifugal vacuum pumps are independently debugged and operated, the system controls the first-stage inlet switching valve 501, the first-stage exhaust parallel switching valve 502, and the series switching valve 503 to be closed, and controls the pre-parallel switching valve 504 to be opened, so that the flow comes from the flow pipe 101, the first-stage inlet pipe 102, passes through the pre-parallel switching valve 504, and directly reaches the second-stage inlet pipe 105 and enters the second-stage centrifugal vacuum pump 41, and then passes through the third-stage inlet pipe 106 and enters the third-stage centrifugal vacuum pump 42, and then passes through the third-stage exhaust pipe 107 and reaches the flow exhaust pipe 108 and is discharged.

[0049] As shown in FIG. 1, the system comprises a first-stage centrifugal vacuum pump unit 40, a second-stage centrifugal vacuum pump 41, a third-stage centrifugal vacuum pump 42, a flow pipe 101, a first-stage inlet pipe 102, a three-way flow dividing pipe 103, a first-stage exhaust pipe 104, a second-stage inlet pipe 105, a third-stage inlet pipe 106, a third-stage exhaust pipe 107, a flow exhaust pipe 108, a first-stage inlet switching valve 501, a first-stage exhaust parallel switching valve 502, a series switching valve 503, a pre-parallel switching valve 504, and a plurality of precision regulating valves 200. Figure 7 When the first-stage vacuum pump unit and the two-stage and three-stage centrifugal vacuum pumps are operated in parallel, the system controls the first-stage inlet switching valve 501, the first-stage exhaust parallel switching valve 502, and the pre-parallel switching valve 504 to be opened, and controls the series switching valve 503 to be closed, so that the flow first passes through the first-stage inlet switching valve 501 and the three-way flow dividing pipe 103 and enters the first-stage centrifugal vacuum pump unit, and then flows to the first-stage exhaust pipe 104 and directly reaches the second-stage centrifugal vacuum pump 41 through the second-stage inlet pipe 105, and then enters the third-stage centrifugal vacuum pump 42 through the third-stage inlet pipe 106, and then passes through the third-stage exhaust pipe 107 and reaches the flow exhaust pipe 108 and is discharged. Figure 5 and Figure 6 The two gas operation paths shown in FIG. 1 are parallel.

[0050] As shown in FIG. 1, the system comprises a first-stage centrifugal vacuum pump unit 40, a second-stage centrifugal vacuum pump 41, a third-stage centrifugal vacuum pump 42, a flow pipe 101, a first-stage inlet pipe 102, a three-way flow dividing pipe 103, a first-stage exhaust pipe 104, a second-stage inlet pipe 105, a third-stage inlet pipe 106, a third-stage exhaust pipe 107, a flow exhaust pipe 108, a first-stage inlet switching valve 501, a first-stage exhaust parallel switching valve 502, a series switching valve 503, a pre-parallel switching valve 504, and a plurality of precision regulating valves 200. Figure 8 When the first-stage vacuum pump unit and the two-stage and three-stage centrifugal vacuum pumps are operated in series, the system controls the first-stage inlet switching valve 501 and the series switching valve 503 to be opened, and controls the first-stage exhaust parallel switching valve 502 and the pre-parallel switching valve 504 to be closed, so that the flow first passes through the first-stage inlet switching valve 501 and the three-way flow dividing pipe 103 and enters the first-stage centrifugal vacuum pump unit, and then flows to the first-stage exhaust pipe 104 and directly reaches the second-stage centrifugal vacuum pump 41 through the second-stage inlet pipe 105, and then enters the third-stage centrifugal vacuum pump 42 through the third-stage inlet pipe 106, and then passes through the third-stage exhaust pipe 107 and reaches the flow exhaust pipe 108 and is discharged.

[0051] In addition, it is worth noting that when the system is operated to maintain a vacuum environment, no air supplement is needed, at which time the plurality of precision regulating valves are controlled to be closed; and when the series and parallel modes are switched, the system will have a pressure value fluctuation, at which time the plurality of precision regulating valves are controlled to be opened, so as to supplement air in time when the air pressure is insufficient.

[0052] In summary, in the aforementioned ultra-wide operating condition multi-stage time-sharing series-parallel centrifugal vacuum pump system, the multi-stage time-sharing series-parallel centrifugal vacuum pump configuration allows for different operating modes, thus covering a wider range of operating conditions and increasing surge margin. Combined with the precision regulating valve, it enables gas replenishment operations based on system conditions, reducing the adverse effects of gas competition. Furthermore, by pre-calculating the operating range of different modes, planning operating strategies, and pre-writing them into the control system, it is possible to control the first-stage inlet switching valve 501, the first-stage exhaust parallel switching valve 502, the series switching valve 503, and the pre-parallel switching valve 504 to be in different states under different operating conditions. This achieves time-sharing series-parallel control of the first-stage vacuum pump unit and the second and third-stage centrifugal vacuum pumps, effectively reducing system control complexity. The modular design of the unit facilitates transportation, installation, and maintenance.

[0053] Example 2:

[0054] like Figures 9-10 Buffer tanks 6 are connected in series on the two arms of the three-way diverter 103 near the outer ends of the two primary centrifugal vacuum pumps 21, the secondary intake pipe 105 near the outer end of the secondary centrifugal vacuum pump 41, the tertiary intake pipe 106 near the outer end of the tertiary centrifugal vacuum pump 42, and the manifold exhaust pipe 108. The buffer tank 6 on the manifold exhaust pipe 108 is located between the end of the dual-flow-channel pressure relief plate 7 and the quick-closing valve. Figure 11 The buffer tank 6 is equipped with a stacked pressure relief assembly, which includes multiple dual-channel pressure relief plates 7 and multiple conical pressure relief cylinders 8 that are fixedly connected between the air inlet of the buffer tank 6 and the adjacent dual-channel pressure relief plates 7, as well as between two adjacent dual-channel pressure relief plates 7. Multiple connecting blocks 71 are fixedly connected between the outer end of the dual-channel pressure relief plate 7 and the inner wall of the buffer tank 6. The multiple conical pressure relief cylinders 8 and the dual-channel pressure relief plates 7 are connected in sequence and along the direction of air flow. The last dual-channel pressure relief plate 7 is directly opposite the exhaust port of the buffer tank 6 and is directly connected to the inside of the buffer tank 6. When the gas pressure is too high, it is discharged from the last dual-channel pressure relief plate 7 after being relieved by all the dual-channel pressure relief plates 7 and conical pressure relief cylinders 8 in the buffer tank 6. It can be discharged directly into the buffer tank 6 and then discharged from the buffer tank 6.

[0055] like Figure 11 and Figure 13The double-flow relief plate 7 is provided with a plurality of relief straight holes 702 arranged in a ring array, and a plurality of L-shaped exhaust holes 701 arranged in a ring array. The L-shaped exhaust hole array, the relief straight hole array, and the flow limiting ring 72 are coaxially arranged and sequentially arranged in a direction away from the axis. The plurality of L-shaped exhaust holes 701 and the relief straight holes 702 are staggered. The exhaust side of the relief straight hole 702 is communicated with the rear conical relief cylinder 8. The exhaust side of the L-shaped exhaust hole 701 is directly communicated with the inside of the buffer tank 6. The double-flow relief plate 7 is fixedly connected with the flow limiting ring 72 near the gas inlet side of the buffer tank 6. The conical relief cylinder 8 includes a conical ring 83 fixedly connected with the radial inner wall of the buffer tank 6 or the side surface of the double-flow relief plate 7 facing the gas inlet end of the buffer tank 6, a plurality of split rings 81 arranged in a ring array and slidably connected with the other end surface of the double-flow relief plate 7, and a plurality of path modification assemblies fixedly connected with the middle part of the split rings 81. The path modification assembly includes a sealing plate 821 and a connecting rod 822 fixedly connected between the sealing plate 821 and the middle part of the inner wall of the split ring 81. When the split ring 81 is in contact with the flow limiting ring 72, the sealing plate 821 completely covers the L-shaped exhaust hole 701. Figure 13 When the gas pressure is small and it is difficult to push the conical relief cylinder 8 to expand, it does not need to be relieved, and the gas can be directly discharged to the buffer tank 6 along the L-shaped exhaust hole 701, and then continue to be discharged outward. Figure 14 When the gas pressure is too high and needs to be relieved, under the action of the gas pressure, the small-diameter end of the conical relief cylinder 8 is expanded until it is turned over the relief straight hole 702, so that the gas in the conical relief cylinder 8 flows into the next conical relief cylinder 8 through the relief straight hole 702, and the relief continues, realizing self-adaptive relief.

[0056] The outer end of the conical ring 83 is further fixedly connected with an outer sealing layer 84. The outer sealing layer 84 is in contact with the surface of the connecting block 71 and the double-flow relief plate 7. The end of the outer sealing layer 84 away from the conical ring 83 crosses the flow limiting ring 72 and is fixedly connected with the outer wall of the flow limiting ring 72. The outer sealing layer 84 is made of flexible sealing material. The gap between the double-flow relief plate 7 and the conical relief cylinder 8 is effectively sealed by the outer sealing layer 84, so that the gas is not easy to leak into the buffer tank 6 along the gap between the double-flow relief plate 7 and the conical relief cylinder 8 before being relieved, thereby effectively avoiding the influence of the unrelieved gas on the stability of the system.

[0057] The end of each of the plurality of split rings 81 close to each other is provided with a receiving groove. Adjacent two receiving grooves are fixedly connected with a reset elastic strip 85. The reset elastic strip 85 is made of elastic material. When the two split rings 81 are in contact with each other, the reset elastic strip 85 is in a straightened state. The reset elastic strip 85 can assist the reset of the conical ring 83 after the relief is completed, which is convenient for the relief in the next series-parallel switching.

[0058] As Figure 12 When the gas pressure is large, after the gas enters the conical relief cylinder 8, it can push the conical relief cylinder 8 from inside to outside under the action of gas pressure, so that the inner diameter of the conical relief cylinder 8 gradually expands towards the outlet of the double-channel relief plate 7. On the one hand, it can consume a certain gas pressure, and on the other hand, as Figure 14 During the expansion process, the path modification assembly will be moved, and the L-shaped exhaust hole 701 will be gradually blocked, and the gas will be forced to be discharged from the straight relief hole 702 to the next conical relief cylinder 8, and then be relieved again. When the pressure is not enough to make the next conical relief cylinder 8 expand again after one or more relief, the path modification assembly cannot cover or cannot completely cover the L-shaped exhaust hole 701, the gas will be directly discharged from the L-shaped exhaust hole 701 to the buffer tank 6, and then discharged along the discharge end of the buffer tank 6. Figure 12 15 When the gas pressure is large, after the gas enters the conical relief cylinder 8, it can push the conical relief cylinder 8 from inside to outside under the action of gas pressure, so that the inner diameter of the conical relief cylinder 8 gradually expands towards the outlet of the double-channel relief plate 7. On the one hand, it can consume a certain gas pressure, and on the other hand, as

[0059] By setting the buffer tank 6 containing the laminated relief assembly at each key pipeline node and the precision regulating valve on the inlet pipe 101 and the secondary inlet pipe, the pressure can be relieved or supplemented adaptively when the mode is switched or the gas flow is suddenly changed, the pressure fluctuation peak value is effectively inhibited, the "gas stealing" and transient pressure impact problems are overcome, and the efficiency and stability of the system in the ultra-wide operating condition and long-time variable operating condition are ensured.

[0060] The above is only the preferred specific embodiment of the present application; all the protection scope of the present application, any person skilled in the art according to the technical solution and the improvement concept of the present application within the technical range disclosed by the present application, equivalent replacement or change, should be covered in the protection scope of the present application.​

Claims

1. An ultra-wide operating condition multi-stage time-sharing series-parallel centrifugal vacuum pump system, comprising an inflow pipe (101), a first-stage intake pipe (102) fixedly connected with the inflow pipe (101), a three-way distribution pipe (103) fixedly connected with the middle part of the first-stage intake pipe (102), a first-stage vacuum pump unit connected with the three-way distribution pipe (103), a second-stage centrifugal vacuum pump (41), a third-stage centrifugal vacuum pump (42) and two variable frequency units, a third-stage intake pipe (106) being fixedly connected between the exhaust end of the second-stage centrifugal vacuum pump (41) and the air intake end of the third-stage centrifugal vacuum pump (42), characterized in that: The primary vacuum pump unit comprises two primary centrifugal vacuum pumps (21), a secondary air inlet pipe (105) fixedly connected between the end of the primary air inlet pipe (102) and the air inlet of the secondary centrifugal vacuum pump (41), and a pre-parallel switch valve (504) installed at the connection position of the two, the air inlets of the two primary centrifugal vacuum pumps (21) are fixedly connected with two exhaust ends of a three-way shunt pipe (103), a primary inlet switch valve (501) is fixedly installed at the air inlet end of the three-way shunt pipe (103), the exhaust ends of the two primary centrifugal vacuum pumps (21) are fixedly connected with a primary exhaust pipe (104), one end of the primary exhaust pipe (104) is fixedly connected with a converging exhaust pipe (108), a tertiary exhaust pipe (107) is fixedly connected between the exhaust end of the tertiary centrifugal vacuum pump (42) and the converging exhaust pipe (108), the other end of the primary exhaust pipe (104) is fixedly connected with the outer end of the secondary air inlet pipe (105) and communicates with the outer end of the secondary air inlet pipe (105), a primary exhaust parallel switch valve (502) is fixedly installed at the outer end of the primary exhaust pipe (104) close to the converging exhaust pipe (108), a series switch valve (503) is fixedly installed at the outer end of the primary exhaust pipe (104) close to the secondary air inlet pipe (105), the outer end of the primary exhaust pipe (104) is further fixedly connected with a gas supplement pipe (109), a plurality of precision regulating valves are fixedly installed at the outer ends of the air inlet pipe (101) and the gas supplement pipe (109), a cooler (3) is connected in series on the one end of the air inlet pipe (101), the primary exhaust pipe (104) away from the converging exhaust pipe (108), and the tertiary air inlet pipe (106), the gas supplement pipe (109) is located between the cooler (3) and the series switch valve (503), and the primary exhaust parallel switch valve (502) and the series switch valve (503) are respectively located at the outer sides of the exhaust ports of the two primary centrifugal vacuum pumps (21), and a quick stop valve is further installed on the converging exhaust pipe (108). The two arms of the three-way shunt pipe (103) are close to the outer ends of the two primary centrifugal vacuum pumps (21), the outer end of the secondary air inlet pipe (105) is close to the secondary centrifugal vacuum pump (41), the outer end of the tertiary air inlet pipe (106) is close to the tertiary centrifugal vacuum pump (42), and the converging exhaust pipe (108) is all connected in series with a buffer tank (6), the buffer tank (6) is internally provided with a laminated pressure relief assembly, the laminated pressure relief assembly comprises a plurality of double-flow pressure relief plates (7), a plurality of conical pressure relief cylinders (8) fixedly connected between the air inlets of the buffer tank (6) and adjacent double-flow pressure relief plates (7) and between adjacent two double-flow pressure relief plates (7), and a plurality of connecting blocks (71) fixedly connected between the outer ends of the double-flow pressure relief plates (7) and the inner walls of the buffer tank (6).

2. The ultra-wide-range multi-stage time-division series-parallel centrifugal vacuum pump system according to claim 1, characterized in that: The variable frequency unit comprises a double-shaft variable frequency motor (22) and two gearboxes (23) connected with the two output shafts of the double-shaft variable frequency motor (22), respectively, and the two primary centrifugal vacuum pumps (21) share one variable frequency unit, and the secondary centrifugal vacuum pump (41) and the tertiary centrifugal vacuum pump (42) share one variable frequency unit.

3. The ultra-wide-range multi-stage time-division series-parallel centrifugal vacuum pump system according to claim 2, characterized in that: A plurality of said conical relief cylinders (8) and double-channel relief plates (7) are sequentially communicated, and the last said double-channel relief plate (7) is directly communicated with the inside of the buffer tank (6) along the direction of air movement.

4. The super-wide-range multi-stage time-division series-parallel centrifugal vacuum pump system according to claim 3, characterized in that: A plurality of L-shaped exhaust holes (701) and a plurality of relief straight holes (702) are arranged in an annular array on the double-channel relief plate (7), the exhaust side of the relief straight hole (702) is communicated with the next conical relief cylinder (8), the exhaust side of the L-shaped exhaust hole (701) is directly communicated with the inside of the buffer tank (6), and the double-channel relief plate (7) is fixedly connected with a flow limiting ring (72) near the air inlet side of the buffer tank (6).

5. The ultra-wide-range multi-stage time-division series-parallel centrifugal vacuum pump system according to claim 4, characterized in that: The L-shaped exhaust hole (701) array, the relief straight hole (702) array, and the flow limiting ring (72) are coaxially arranged, and are sequentially arranged in a direction away from the axis, and a plurality of L-shaped exhaust holes (701) and relief straight holes (702) are arranged in an interlaced manner.

6. The ultra-wide-range multi-stage time-division series-parallel centrifugal vacuum pump system according to claim 5, characterized in that: The conical relief cylinder (8) comprises a conical ring piece (83) fixedly connected with the radial inner wall of the buffer tank (6) or the side surface of the double-channel relief plate (7) away from the air inlet end of the buffer tank (6), a plurality of split rings (81) arranged in an annular array and slidably connected with the other side surface of the double-channel relief plate (7), and a plurality of path modification assemblies respectively fixedly connected with the middle portions of the plurality of split rings (81), the outer end of the conical ring piece (83) is further fixedly connected with an outer sealing layer (84), the outer sealing layer (84) is attached to the surface of the connecting block (71) and the double-channel relief plate (7), and the end of the outer sealing layer (84) away from the conical ring piece (83) crosses the flow limiting ring (72) and is fixedly connected with the outer wall of the flow limiting ring (72), and the outer sealing layer (84) is made of a flexible sealing material.

7. The ultra-wide-range multi-stage time-division series-parallel centrifugal vacuum pump system according to claim 6, characterized in that: The end portions of the plurality of split rings (81) are respectively provided with accommodating grooves, and a reset elastic strip (85) is fixedly connected between adjacent two accommodating grooves.

8. The ultra-wide-range multi-stage time-division series-parallel centrifugal vacuum pump system according to claim 7, characterized in that: The path modification assembly comprises a sealing plate (821) and a connecting rod (822) fixedly connected between the sealing plate (821) and the inner wall of the split ring (81), and when the split ring (81) abuts against the flow limiting ring (72), the sealing plate (821) completely covers the L-shaped exhaust hole (701).

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