Inlet high-pressure multi-stage centrifugal pump with low-pressure sealing function

Abstract

The invention relates to the technical field of centrifugal pumps, in particular to an inlet high-pressure multi-stage centrifugal pump with a low-pressure sealing function, and solves the problems that when an existing centrifugal pump is used for conveying liquid to a reaction kettle in wastewater treatment, the liquid pressure is high, so that the structural sealing pressure is too large, the structural sealing failure is easily caused, and the service life is shortened. Comprising a high-pressure suction mechanism, a high-pressure multi-stage centrifugal mechanism and a transmission shaft, the high-pressure suction mechanism is installed on the outer side of the front end of the transmission shaft and comprises a first suction shell, and a second suction shell is fixedly installed at the rear end of the first suction shell; a high-pressure suction cavity is formed in the inner side of the first suction shell and the inner side of the second suction shell, and a shaft end low-pressure maintaining assembly is installed on the inner side of the high-pressure suction cavity. According to the centrifugal pump, the pressure of the liquid is reduced when the high-pressure liquid is centrifugally conveyed, the sealing pressure can be reduced while the sealing of the centrifugal pump is cooled, the sealing service life of the centrifugal pump is prolonged, and the sealing cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of centrifugal pumps, and particularly to an inlet high-pressure multistage centrifugal pump with a low-pressure sealing function. Background Technique

[0002] A centrifugal pump drives an impeller to rotate at a high speed through a motor, so that the liquid is thrown to the outer edge of the impeller under the action of centrifugal force, and flows into the pressure water pipeline of the water pump through the flow channel of the volute, thereby realizing the transportation of the liquid. At the same time as the liquid is thrown to the outlet of the impeller, a low pressure is formed at the center of the impeller inlet. Under the action of this pressure difference, the liquid in the liquid suction tank continuously enters the impeller through the suction pipeline and the suction chamber of the pump, forming a continuous liquid transportation process. By adjusting the rotational speed of the impeller and the number of impellers, the head and flow rate of the pump can be changed, thereby realizing the regulation of the liquid pressure. Most centrifugal pumps are two-end supported multistage pumps, using ultra-high pressure mechanical seals, and the impellers are arranged back-to-back to achieve self-balanced axial force.

[0003] When the existing centrifugal pump conveys liquid to the reactor in wastewater treatment, the liquid pressure is high, which makes the structural sealing pressure too high, easily causing the failure of the structural seal and shortening the service life. Therefore, it does not meet the existing requirements, and for this reason, we propose an inlet high-pressure multistage centrifugal pump with a low-pressure sealing function. Summary of the Invention

[0004] The purpose of the present invention is to provide an inlet high-pressure multistage centrifugal pump with a low-pressure sealing function, so as to solve the problem that when the existing centrifugal pump conveys liquid to the reactor in wastewater treatment, the liquid pressure is high, which makes the structural sealing pressure too high, easily causing the failure of the structural seal and shortening the service life as mentioned in the above background technique.

[0005] To achieve the above object, the present invention provides the following technical solution: A high-pressure multistage centrifugal pump at the inlet with a low-pressure sealing function, comprising a high-pressure suction mechanism, a high-pressure multistage centrifugal mechanism and a transmission shaft. The high-pressure suction mechanism is installed on the outer side of the front end of the transmission shaft. The high-pressure suction mechanism includes a first suction housing, and a second suction housing is fixedly installed at the rear end of the first suction housing. A high-pressure suction cavity is provided inside the first suction housing and the second suction housing. An axial low-pressure maintaining assembly is installed inside the high-pressure suction cavity. The axial low-pressure maintaining assembly includes an axial balance seat. A liquid guiding hole is provided in the middle of the axial balance seat. A second separating follower ring is installed at the rear end of the axial balance seat. A second bearing snap ring is installed at the rear end of the second separating follower ring. A sliding bearing inner sleeve is installed at the rear end of the second bearing snap ring. A first flat key liquid guiding groove is provided between the sliding bearing inner sleeve and the transmission shaft. The outer side of the sliding bearing inner sleeve is slidably connected with a sliding bearing outer sleeve. A first bearing snap ring is installed at the rear end of the sliding bearing inner sleeve. A low-pressure liquid guiding gap is provided between the axial balance seat, the second separating follower ring, the sliding bearing outer sleeve, the sliding bearing inner sleeve and the first bearing snap ring.

[0006] Preferably, a high-pressure multistage centrifugal mechanism is installed at the rear end of the high-pressure suction mechanism. The high-pressure multistage centrifugal mechanism includes a pump casing, and a pump cover is fixedly installed at the rear end of the pump casing. A high-pressure centrifugal cavity is provided between the pump casing and the pump cover. A multistage centrifugal assembly is installed inside the high-pressure centrifugal cavity. A pressure reducing and sealing seat is fixedly installed inside the pump cover. A connecting shaft sleeve is rotatably connected inside the pressure reducing and sealing seat. A second separating follower ring is installed at the front end of the connecting shaft sleeve. A mechanical sealing seat is fixedly installed on the rear end face of the pump cover.

[0007] Preferably, the multistage centrifugal assembly includes a second impeller cover. A plurality of first impeller covers are installed at the front end of the second impeller cover. The second suction housing and the pump cover are fixedly connected through the second impeller cover and the plurality of first impeller covers. Centrifugal flow guiding seats are fixedly installed inside the second impeller cover and the plurality of first impeller covers. Centrifugal impellers are installed between the second impeller cover and the centrifugal flow guiding seats and the transmission shaft. A support connecting ring is rotatably connected to the front end of the centrifugal impeller. A second flat key liquid guiding groove is provided between the transmission shaft and the plurality of centrifugal impellers.

[0008] Preferably, the front end of the second suction housing is fixedly connected to the pump casing. The high-pressure suction cavity is connected in a through manner with the high-pressure centrifugal cavity. A liquid outlet is provided at the upper end of the pump casing. The high-pressure centrifugal cavity is connected in a through manner with the liquid outlet. The first suction housing, the second suction housing, the pump casing and the pump cover are coaxial.

[0009] Preferably, the plurality of support connecting rings are fixedly connected to the second suction housing, the second impeller cover and the plurality of first impeller covers. The centrifugal flow guiding seat is rotatably connected to the centrifugal impeller. The transmission shaft is fixedly connected to the plurality of centrifugal impellers.

[0010] Preferably, the liquid guiding hole is connected to the high-pressure suction chamber through a low-pressure liquid guiding gap. The outer sleeve of the sliding bearing is fixedly connected to the first suction housing and the second suction housing. The inner sleeve of the sliding bearing is fixedly connected to the transmission shaft through a first bearing snap ring and a second bearing snap ring. The shaft end balance seat is fixedly connected to the first suction housing. The shaft end balance seat is rotatably connected to the second bearing snap ring through a second separating follower ring. The shaft end balance seat, the second separating follower ring, the second bearing snap ring, the inner sleeve of the sliding bearing, the first bearing snap ring, and the outer sleeve of the sliding bearing are coaxial.

[0011] Preferably, a bearing sealing mechanism is installed at the rear end of the high-pressure multi-stage centrifugal mechanism. The bearing sealing mechanism includes a bearing housing. The front end of the bearing housing is fixedly connected to the pump cover. A bearing gland is fixedly installed at the rear end of the bearing housing. A grease injection chamber is provided between the bearing housing and the bearing gland. A first bearing isolation ring is installed at the front end of the grease injection chamber. A second bearing isolation ring is installed at the rear end of the grease injection chamber. The bearing housing is rotatably connected to the transmission shaft through the first bearing isolation ring. The bearing gland is rotatably connected to the transmission shaft through the second bearing isolation ring.

[0012] Preferably, two support bearings are installed in the middle of the grease injection chamber. A bearing bushing is installed inside the two support bearings. A bearing limit ring is installed on the rear end face of one of the support bearings. The bearing housing is rotatably connected to the transmission shaft through the two support bearings. The bearing limit ring is fixedly connected to the transmission shaft. A grease injection port is provided on the outer surface of the bearing housing.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] 1. In the present invention, high-pressure liquid is introduced and conveyed to the inside of the high-pressure centrifugal chamber through the high-pressure suction chambers on the inner sides of the first suction housing and the second suction housing. The transmission shaft synchronously drives the shaft end low-pressure maintaining assembly and the multi-stage centrifugal assembly to rotate. Then, the high-pressure liquid is subjected to multi-stage centrifugal transportation through multiple centrifugal impellers and centrifugal flow guiding seats. The shaft end low-pressure maintaining assembly and the bearing sealing mechanism can radially support both ends of the transmission shaft to maintain the stable rotation of the transmission shaft. Among them, the pressure reduction sealing seat and the mechanical sealing seat can perform two-stage sealing on the high-pressure centrifugal chamber, effectively improving the sealing performance of the high-pressure liquid in the high-pressure centrifugal chamber;

[0015] 2. In the present invention, the liquid guiding hole and the high-pressure suction chamber are connected through a low-pressure liquid guiding gap. The first part of the high-pressure liquid enters the inner side of the low-pressure liquid guiding gap from the high-pressure suction chamber, achieving the reduction of the high-pressure liquid to low-pressure liquid. At the same time, the liquid is transported between the pressure-reducing sealing seat and the mechanical sealing seat through the first flat key liquid guiding groove and the second flat key liquid guiding groove and maintained at a low pressure state. The second part of the high-pressure liquid undergoes multi-stage centrifugation through the multi-stage centrifugation component and is discharged. The third part of the high-pressure liquid penetrates into the pressure-reducing sealing seat through the pressure-reducing sealing seat, achieving the reduction of the high-pressure liquid to low-pressure liquid. The liquid in the low-pressure liquid guiding gap and between the mechanical sealing seat and the pressure-reducing sealing seat is in a low-pressure state, enabling the low-pressure liquid to cool the shaft-end low-pressure maintaining component, the mechanical sealing seat, and the pressure-reducing sealing seat, and reducing the sealing pressure of the shaft-end low-pressure maintaining component, the mechanical sealing seat, and the pressure-reducing sealing seat, thereby prolonging the sealing service life of the centrifugal pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic structural diagram of the whole of the present invention;

[0017] Figure 2 is a schematic cross-sectional structural diagram of the whole of the present invention;

[0018] Figure 3 is a schematic partial cross-sectional structural diagram of the transmission shaft of the present invention;

[0019] Figure 4 is a schematic partial cross-sectional structural diagram of the shaft-end low-pressure maintaining component of the present invention;

[0020] Figure 5 is a schematic partial cross-sectional structural diagram of the high-pressure suction mechanism of the present invention;

[0021] Figure 6 is a schematic partial cross-sectional structural diagram of the multi-stage centrifugation component of the present invention.

[0022] In the figure: 1. High-pressure suction mechanism; 101. First suction housing; 102. Second suction housing; 103. High-pressure suction chamber; 104. Low-pressure maintaining assembly at the shaft end; 105. Balancing seat at the shaft end; 106. Liquid guiding hole; 107. Second separating follower ring; 108. Outer sleeve of sliding bearing; 109. Inner sleeve of sliding bearing; 110. First bearing snap ring; 111. Second bearing snap ring; 112. First flat key liquid guiding groove; 113. Low-pressure liquid guiding gap; 2. High-pressure multi-stage centrifugal mechanism; 201. Pump housing; 202. Pump cover; 203. High-pressure centrifugal chamber; 204. Multi-stage centrifugal assembly; 205. Mechanical seal seat; 206. Pressure-reducing seal seat; 207. Centrifugal flow guiding seat; 208. Support connecting ring; 209. Centrifugal impeller; 210. First impeller cover; 211. Second impeller cover; 212. Second separating follower ring; 213. Connecting shaft sleeve; 214. Second flat key liquid guiding groove; 3. Bearing sealing mechanism; 301. Bearing housing; 302. Bearing gland; 303. Grease injection chamber; 304. First bearing isolation ring; 305. Support bearing; 306. Bearing bushing; 307. Bearing limit ring; 308. Second bearing isolation ring; 4. Transmission shaft. Detailed implementation manners

[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with 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 the embodiments.

[0024] Please refer to Figure 1 , Figure 2 and Figure 5 , an embodiment provided by the present invention: an inlet high-pressure multi-stage centrifugal pump with a low-pressure sealing function, including a high-pressure suction mechanism 1, a high-pressure multi-stage centrifugal mechanism 2, and a transmission shaft 4. The high-pressure suction mechanism 1 is installed on the outer side of the front end of the transmission shaft 4. The high-pressure suction mechanism 1 includes a first suction housing 101. The second suction housing 102 is fixedly installed at the rear end of the first suction housing 101. A high-pressure suction chamber 103 is provided inside the first suction housing 101 and the second suction housing 102. The high-pressure liquid is introduced through the high-pressure suction chamber 103 inside the first suction housing 101 and the second suction housing 102, and the high-pressure liquid can be shunted.

[0025] Please refer to Figures 2 to 5, a shaft-end low-pressure maintaining assembly 104 is installed inside the high-pressure suction chamber 103. The shaft-end low-pressure maintaining assembly 104 includes a shaft-end balance seat 105, the shaft-end balance seat 105 is fixedly connected to the first suction housing 101, a liquid guiding hole 106 is provided in the middle of the shaft-end balance seat 105, a second separating follower ring 107 is installed at the rear end of the shaft-end balance seat 105, a second bearing snap ring 111 is installed at the rear end of the second separating follower ring 107, a sliding bearing inner sleeve 109 is installed at the rear end of the second bearing snap ring 111, a first flat key liquid guiding groove 112 is provided between the sliding bearing inner sleeve 109 and the transmission shaft 4, the outer side of the sliding bearing inner sleeve 109 is slidably connected with a sliding bearing outer sleeve 108. The shaft-end low-pressure maintaining assembly 104 facilitates radial support for the end of the transmission shaft 4 to maintain stable rotation;

[0026] The sliding bearing outer sleeve 108 is fixedly connected to the first suction housing 101 and the second suction housing 102. A first bearing snap ring 110 is installed at the rear end of the sliding bearing inner sleeve 109. The sliding bearing inner sleeve 109 and the transmission shaft 4 are fixedly connected through the first bearing snap ring 110 and the second bearing snap ring 111. The shaft-end balance seat 105 and the second bearing snap ring 111 are rotatably connected through the second separating follower ring 107. The shaft-end balance seat 105, the second separating follower ring 107, the second bearing snap ring 111, the sliding bearing inner sleeve 109, the first bearing snap ring 110 and the sliding bearing outer sleeve 108 are coaxial. A low-pressure liquid guiding gap 113 is provided between the shaft-end balance seat 105, the second separating follower ring 107, the sliding bearing outer sleeve 108, the sliding bearing inner sleeve 109 and the first bearing snap ring 110. The liquid guiding hole 106 and the high-pressure suction chamber 103 are connected through the low-pressure liquid guiding gap 113. The high-pressure liquid can penetrate into the shaft-end low-pressure maintaining assembly 104 through the low-pressure liquid guiding gap 113, thereby reducing the sealing pressure and facilitating sealing cooling.

[0027] Please refer to Figures 1 to 6, a high-pressure multi-stage centrifugal mechanism 2 is installed at the rear end of the high-pressure suction mechanism 1. The high-pressure multi-stage centrifugal mechanism 2 includes a pump casing 201. The second suction casing 102 is fixedly connected to the front end of the pump casing 201. A pump cover 202 is fixedly installed at the rear end of the pump casing 201. The first suction casing 101, the second suction casing 102, the pump casing 201, and the pump cover 202 are coaxial. A high-pressure centrifugal chamber 203 is provided between the pump casing 201 and the pump cover 202. The high-pressure suction chamber 103 is connected to the high-pressure centrifugal chamber 203 in a through manner. A liquid outlet is provided at the upper end of the pump casing 201. The high-pressure centrifugal chamber 203 is connected to the liquid outlet in a through manner. A multi-stage centrifugal assembly 204 is installed inside the high-pressure centrifugal chamber 203. A pressure-reducing seal seat 206 is fixedly installed inside the pump cover 202. A connecting shaft sleeve 213 is rotatably connected to the inside of the pressure-reducing seal seat 206. A second separating follower ring 212 is installed at the front end of the connecting shaft sleeve 213. A mechanical seal seat 205 is fixedly installed on the rear end face of the pump cover 202. The high-pressure centrifugal chamber 203 can be blocked in two stages through the pressure-reducing seal seat 20 and the mechanical seal seat 205, effectively improving the sealing performance of the high-pressure liquid in the high-pressure centrifugal chamber 203.

[0028] Please refer to Figures 3 to 6 , the multi-stage centrifugal assembly 204 includes a second impeller cover 211. A plurality of first impeller covers 210 are installed at the front end of the second impeller cover 211. The second suction casing 102 and the pump cover 202 are fixedly connected through the second impeller cover 211 and the plurality of first impeller covers 210. Centrifugal flow guide seats 207 are fixedly installed inside the second impeller cover 211 and the plurality of first impeller covers 210. Centrifugal impellers 209 are installed between the second impeller cover 211 and the centrifugal flow guide seat 207 and between the centrifugal flow guide seat 207 and the transmission shaft 4. The transmission shaft 4 is fixedly connected to the plurality of centrifugal impellers 209. The centrifugal flow guide seat 207 is rotatably connected to the centrifugal impeller 209. A support connection ring 208 is rotatably connected to the front end of the centrifugal impeller 209. The plurality of support connection rings 208 are fixedly connected to the second suction casing 102, the second impeller cover 211, and the plurality of first impeller covers 210. A second flat key liquid guide groove 214 is provided between the transmission shaft 4 and the plurality of centrifugal impellers 209. Through the second flat key liquid guide groove 214, it is convenient to transport the low-pressure liquid between the pressure-reducing seal seat 206 and the mechanical seal seat 205, and thus it is convenient to realize the cooling of the seal.

[0029] Please refer to Figure 1 and Figure 2, a bearing seal mechanism 3 is installed at the rear end of the high-pressure multi-stage centrifugal mechanism 2. The bearing seal mechanism 3 includes a bearing housing 301. The front end of the bearing housing 301 is fixedly connected to the pump cover 202. A bearing gland 302 is fixedly installed at the rear end of the bearing housing 301. A grease injection chamber 303 is provided between the bearing housing 301 and the bearing gland 302. A grease injection port is provided on the outer surface of the bearing housing 301. A first bearing isolation ring 304 is installed at the front end of the grease injection chamber 303. A second bearing isolation ring 308 is installed at the rear end of the grease injection chamber 303. The bearing housing 301 and the transmission shaft 4 are rotationally connected through the first bearing isolation ring 304. The bearing gland 302 and the transmission shaft 4 are rotationally connected through the second bearing isolation ring 308. The grease injection chamber 303 can be filled with lubricating grease through the grease injection port, thereby maintaining the stable rotation of the transmission shaft 4.

[0030] Two support bearings 305 are installed in the middle of the grease injection chamber 303. A bearing bushing 306 is installed inside the two support bearings 305. A bearing limit ring 307 is installed on the rear end face of one of the support bearings 305. The bearing housing 301 and the transmission shaft 4 are rotationally connected through the two support bearings 305. The bearing limit ring 307 is fixedly connected to the transmission shaft 4. The two support bearings 305 can radially support the shaft end of the transmission shaft 4.

[0031] In summary, connect the centrifugal pump to the conveying pipeline, turn on the power supply, introduce and convey the high-pressure liquid into the inside of the high-pressure centrifugal chamber 203 through the high-pressure suction chamber 103 inside the first suction housing 101 and the second suction housing 102, drive the transmission shaft 4 to rotate through an external power source, and then the transmission shaft 4 synchronously drives the shaft-end low-pressure maintaining assembly 104 and the multi-stage centrifugal assembly 204 to rotate. At this time, the transmission shaft 4 drives a plurality of centrifugal impellers 209 to rotate inside the centrifugal guide seat 207 and the second impeller cover 211. Then, the high-pressure liquid is discharged from the liquid outlet provided at the upper end of the pump casing 201 after being multi-stage centrifuged by the plurality of centrifugal impellers 209 and the centrifugal guide seat 207;

[0032] The shaft-end low-pressure maintaining assembly 104 and the bearing seal mechanism 3 can radially support both ends of the transmission shaft 4 to maintain the stable rotation of the transmission shaft 4. Among them, the high-pressure centrifugal chamber 203 can be blocked in two stages through the pressure-reducing seal seat 206 and the mechanical seal seat 205, effectively improving the sealing performance of the high-pressure liquid in the high-pressure centrifugal chamber 203. During the centrifugal transportation of the high-pressure liquid, it flows in three parts;

[0033] Specifically, a low-pressure liquid guiding gap 113 is provided between the shaft-end balance seat 105, the second separating follower ring 107, the outer sliding bearing 108, the inner sliding bearing 109 and the first bearing snap ring 110. The liquid guiding hole 106 is connected to the high-pressure suction chamber 103 through the low-pressure liquid guiding gap 113. During the mutual sliding of the outer sliding bearing 108 and the inner sliding bearing 109, the first part of the high-pressure liquid enters the inner side of the low-pressure liquid guiding gap 113 from the high-pressure suction chamber 103, so as to reduce the high-pressure liquid to low-pressure liquid and guide it to the space between the first suction housing 101 and the shaft-end balance seat 105 through the liquid guiding hole 106. At the same time, the liquid is conveyed to the space between the pressure-reducing seal seat 206 and the mechanical seal seat 205 through the first flat key liquid guiding groove 112 and the second flat key liquid guiding groove 214 and maintained in a low-pressure state;

[0034] The second part of the high-pressure liquid is centrifuged in multiple stages through the multi-stage centrifugation assembly 204 and discharged. The third part of the high-pressure liquid seeps through the pressure-reducing seal seat 206 to reduce the high-pressure liquid to low-pressure liquid. The liquid between the low-pressure liquid guiding gap 113 and between the mechanical seal seat 205 and the pressure-reducing seal seat 206 is in a low-pressure state, so that the low-pressure liquid can cool the shaft-end low-pressure maintaining assembly 104, the mechanical seal seat 205 and the pressure-reducing seal seat 206, and can reduce the sealing pressure of the shaft-end low-pressure maintaining assembly 104, the mechanical seal seat 205 and the pressure-reducing seal seat 206, thereby prolonging the sealing service life of the centrifugal pump.

[0035] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed claim.

Claims

1. An inlet high-pressure multi-stage centrifugal pump with a low-pressure sealing function, comprising a high-pressure suction mechanism (1), a high-pressure multi-stage centrifugal mechanism (2) and a transmission shaft (4), characterized in that: A high-pressure suction mechanism (1) is installed on the outer side of the front end of the transmission shaft (4). The high-pressure suction mechanism (1) includes a first suction housing (101). A second suction housing (102) is fixedly installed at the rear end of the first suction housing (101). A high-pressure suction chamber (103) is provided inside the first suction housing (101) and the second suction housing (102). An axial-end low-pressure maintaining assembly (104) is installed inside the high-pressure suction chamber (103). The axial-end low-pressure maintaining assembly (104) includes an axial-end balance seat (105). A liquid guiding hole (106) is provided in the middle of the axial-end balance seat (105). A second separating follower ring (107) is installed at the rear end of the axial-end balance seat (105). A second bearing snap ring (111) is installed at the rear end of the second separating follower ring (107). A sliding bearing inner sleeve (109) is installed at the rear end of the second bearing snap ring (111). A first flat key liquid guiding groove (112) is provided between the sliding bearing inner sleeve (109) and the transmission shaft (4). A sliding bearing outer sleeve (108) is slidably connected to the outer side of the sliding bearing inner sleeve (109). A first bearing snap ring (110) is installed at the rear end of the sliding bearing inner sleeve (109). A low-pressure liquid guiding gap (113) is provided between the axial-end balance seat (105), the second separating follower ring (107), the sliding bearing outer sleeve (108), the sliding bearing inner sleeve (109), and the first bearing snap ring (110).

2. The inlet high-pressure multistage centrifugal pump with a low-pressure sealing function according to claim 1, wherein: A high-pressure multi-stage centrifugal mechanism (2) is installed at the rear end of the high-pressure suction mechanism (1). The high-pressure multi-stage centrifugal mechanism (2) includes a pump housing (201). A pump cover (202) is fixedly installed at the rear end of the pump housing (201). A high-pressure centrifugal chamber (203) is provided between the pump housing (201) and the pump cover (202). A multi-stage centrifugal assembly (204) is installed inside the high-pressure centrifugal chamber (203). A decompression seal seat (206) is fixedly installed inside the pump cover (202). A connecting shaft sleeve (213) is rotatably connected to the inside of the decompression seal seat (206). A second separating follower ring (212) is installed at the front end of the connecting shaft sleeve (213). A mechanical seal seat (205) is fixedly installed on the rear end face of the pump cover (202).

3. The inlet high-pressure multi-stage centrifugal pump with low-pressure sealing function according to claim 2, wherein: The multi-stage centrifugal assembly (204) includes a second impeller cover (211). A plurality of first impeller covers (210) are installed at the front end of the second impeller cover (211). The second suction housing (102) and the pump cover (202) are fixedly connected through the second impeller cover (211) and the plurality of first impeller covers (210). Centrifugal guide seats (207) are fixedly installed inside both the second impeller cover (211) and the plurality of first impeller covers (210). Centrifugal impellers (209) are installed between the second impeller cover (211) and the centrifugal guide seats (207) and the drive shaft (4). A support connection ring (208) is rotatably connected to the front end of the centrifugal impeller (209). A second flat key liquid guide groove (214) is provided between the drive shaft (4) and the plurality of centrifugal impellers (209).

4. The inlet high-pressure multi-stage centrifugal pump with a low-pressure sealing function according to claim 3, wherein: The second suction housing (102) is fixedly connected to the front end of the pump housing (201). The high-pressure suction chamber (103) is connected to the high-pressure centrifugal chamber (203) in a through manner. A liquid outlet is provided at the upper end of the pump housing (201). The high-pressure centrifugal chamber (203) is connected to the liquid outlet in a through manner. The first suction housing (101), the second suction housing (102), the pump housing (201), and the pump cover (202) are coaxial.

5. The inlet high-pressure multistage centrifugal pump with a low-pressure sealing function according to claim 4, characterized in that: A plurality of the support connection rings (208) are fixedly connected to the second suction housing (102), the second impeller cover (211), and the plurality of first impeller covers (210). The centrifugal guide seat (207) is rotatably connected to the centrifugal impeller (209). The drive shaft (4) is fixedly connected to the plurality of centrifugal impellers (209).

6. The inlet high-pressure multistage centrifugal pump with a low-pressure sealing function according to claim 5, wherein: The liquid guide hole (106) is connected to the high-pressure suction chamber (103) in a through manner through a low-pressure liquid guide gap (113). The sliding bearing outer sleeve (108) is fixedly connected to the first suction housing (101) and the second suction housing (102). The sliding bearing inner sleeve (109) is fixedly connected to the drive shaft (4) through a first bearing snap ring (110) and a second bearing snap ring (111). The shaft end balance seat (105) is fixedly connected to the first suction housing (101). The shaft end balance seat (105) is rotatably connected to the second bearing snap ring (111) through a second separating follower ring (107). The shaft end balance seat (105), the second separating follower ring (107), the second bearing snap ring (111), the sliding bearing inner sleeve (109), the first bearing snap ring (110), and the sliding bearing outer sleeve (108) are coaxial.

7. The inlet high-pressure multistage centrifugal pump with a low-pressure sealing function according to claim 6, characterized in that: A bearing seal mechanism (3) is installed at the rear end of the high-pressure multi-stage centrifugal mechanism (2). The bearing seal mechanism (3) includes a bearing housing (301). The front end of the bearing housing (301) is fixedly connected to the pump cover (202). A bearing gland (302) is fixedly installed at the rear end of the bearing housing (301). A grease injection chamber (303) is provided between the bearing housing (301) and the bearing gland (302). A first bearing isolation ring (304) is installed at the front end of the grease injection chamber (303). A second bearing isolation ring (308) is installed at the rear end of the grease injection chamber (303). The bearing housing (301) and the transmission shaft (4) are rotatably connected through the first bearing isolation ring (304). The bearing gland (302) and the transmission shaft (4) are rotatably connected through the second bearing isolation ring (308).

8. The inlet high-pressure multi-stage centrifugal pump with a low-pressure sealing function according to claim 7, wherein: Two support bearings (305) are installed in the middle of the grease injection chamber (303). A bearing bushing (306) is installed inside the two support bearings (305). A bearing limit ring (307) is installed on the rear end face of one of the support bearings (305). The bearing housing (301) and the transmission shaft (4) are rotatably connected through the two support bearings (305). The bearing limit ring (307) is fixedly connected to the transmission shaft (4). A grease injection port is provided on the outer surface of the bearing housing (301).

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