TWM676593U - Centrifugal high-pressure sewage pump - Google Patents

Abstract

A centrifugal high-pressure sewage pump includes a fixed disc with high and low pressure outlets and a swashplate axial piston pump connected to its lower side. The pump pressurizes the pumped liquid and outputs it through the high-pressure outlet. A filter assembly is connected to the lower side of the swashplate axial piston pump to filter impurities entering the pump. A casing assembly with an inlet and a flow chamber is disposed outside the filter assembly. A motor is integrated at the top to drive a transmission shaft that connects a swashplate axial piston pump and a centrifugal impeller. The centrifugal impeller is located inside the inlet to generate negative pressure, drawing external liquid into the inlet and causing the liquid containing impurities in the flow chamber to be discharged from the low-pressure outlet. In this way, this invention can filter impurities in the liquid and then output it at high pressure after pressurization, and the structure is not easily damaged and is easy to maintain.

Description

Centrifugal high-pressure sewage pump

This invention relates to liquid pressurization pumps; in particular, it refers to a centrifugal high-pressure sludge pump that uses a swashplate axial piston pump to deliver liquid at high pressure.

Existing liquid pressurization pumps, such as vertical submersible pumps, are widely used in applications requiring pressurized liquids, such as sewage or wastewater treatment or supplying cutting fluid to machine tools. These pumps typically include a motor that drives a multi-stage centrifugal impeller to generate centrifugal force, propelling the liquid to be output at the required pressure.

However, the aforementioned existing liquid booster pumps have several limitations in use. When higher liquid pressure is required, liquid booster pumps using multi-stage centrifugal impellers are less effective than swashplate axial piston pumps, but swashplate axial piston pumps have higher requirements for the purity of the pressurized liquid. Because existing liquid booster pumps lack internal filtration mechanisms, they cannot effectively remove metal shavings or impurities from cutting fluid. When integrated with a swashplate axial piston pump and used to pressurize machine tool cutting fluid, the metal shavings in the circulating cutting fluid will cause significant damage to the internal parts of the piston pump, thereby shortening the service life of the liquid booster pump.

In view of this, it is necessary to improve existing liquid booster pumps to overcome the above limitations, so that the liquid booster pump integrating the swashplate axial piston pump can not only stably output high-pressure liquid, but also filter impurities such as metal shavings in the liquid it draws, protect the internal swashplate axial piston pump from damage and make it easy to maintain.

To achieve the above objectives, this invention provides a centrifugal high-pressure sewage pump, comprising a fixed plate, a swashplate axial piston pump, a filter assembly, a casing assembly, a motor, and a centrifugal impeller. The fixed plate has an upper shaft bore and a high-pressure outlet and a low-pressure outlet around its perimeter. The lower side of the fixed plate has a high-pressure inlet and a low-pressure inlet, the high-pressure inlet leading to the high-pressure outlet and the low-pressure inlet leading to the low-pressure outlet. The swashplate axial piston pump is connected to the fixed plate on the upper side and has at least one pressure port and at least one suction port, the at least one pressure port leading to the high-pressure inlet; the swashplate axial piston pump has a pump cover on the lower side, the pump cover having a central shaft hole and at least one inlet hole, the at least one inlet hole leading to the at least one suction port.

The filtration assembly includes an inner filter screen and a cover; the inner filter screen is a tubular mesh and its upper end is connected to the pump cover, the cover is connected to the lower end of the inner filter screen and has a lower axial hole; a filtration chamber is formed between the pump cover, the cover and the inner filter screen, and the filtration chamber communicates with the at least one liquid inlet. The casing assembly includes a lower casing and a base plate. The lower casing is fitted around the inner filter screen and its upper end is connected to the pump cover. The base plate is located directly below the cover and is connected to the lower end of the lower casing. The base plate has a liquid inlet. A flow chamber is formed between the lower casing and the inner filter screen. The liquid inlet leads to the flow chamber, and the flow chamber leads to the low-pressure inlet. The motor is connected to the fixed plate and has a drive shaft. The drive shaft passes sequentially through the upper shaft hole, the middle shaft hole, and the lower shaft hole and is connected to the swashplate axial piston pump. The centrifugal impeller is centrally coupled to the lower end of the transmission shaft, and is located between the cover and the chassis.

In use, this device is attached to a water tank with a fixed plate, and the lower end of the casing assembly is inserted into the liquid in the tank, immersing the inlet in the liquid. When the motor drives the transmission shaft to rotate, it drives the swashplate axial piston pump and causes the centrifugal impeller to rotate. The rotation of the centrifugal impeller generates centrifugal force around its periphery and creates a negative pressure area in the center. This negative pressure area generates an attractive force, drawing the liquid into the flow chamber through the inlet. Part of the liquid entering the flow chamber is filtered by the internal filter and then enters the filtration chamber, while the other part flows from the low-pressure inlet to the low-pressure outlet and is discharged outward. Since it is not filtered, the liquid discharged from the low-pressure outlet is wastewater. The liquid entering the filtration chamber flows from at least one inlet to at least one suction port, then enters the swashplate axial piston pump through the suction port. After being pressurized by the swashplate axial piston pump, it flows through at least one pressure port to the high-pressure inlet, so that the pressurized liquid is finally discharged from the high-pressure outlet. Since the liquid discharged from the high-pressure outlet has been filtered, it is clean water. With the above-described structure of the centrifugal high-pressure pump, when the motor of this invention is started, filtered and pressurized clean water is simultaneously output from the high-pressure outlet, and wastewater is output from the low-pressure outlet.

When this invention is applied to wastewater containing impurities, such as cutting fluid containing metal shavings in machine tools, the wastewater discharged from the low-pressure outlet can be connected to an external filtration device for cleaning, and then circulated back into the water tank for use by the centrifugal high-pressure pump. The high-pressure cutting fluid output from the high-pressure outlet is filtered and pressurized before being connected to the machine tool's clean water supply to power the cutting tools. The advantage of this invention lies in the fact that, thanks to the integrated design of the swashplate axial piston pump, the high-pressure outlet can output high-pressure cutting fluid, meeting the machine tool's cutting fluid pressure requirements. Furthermore, since the cutting fluid supplied to the centrifugal high-pressure pump in the filtration chamber is filtered by the internal filter screen before entering the filtration chamber, it ensures that the cutting fluid pressurized by the swashplate axial piston pump is relatively clean, preventing impurities such as metal shavings from damaging the parts of the swashplate axial piston pump. This extends the service life of the swashplate axial piston pump and makes this invention easy to maintain.

Furthermore, this invention incorporates a turbine impeller at the lower end of the transmission shaft. This turbine impeller, positioned within the flow chamber and surrounding the inner filter screen, not only utilizes the thrust generated by the centrifugal impeller but also, through the rotational motion of the turbine impeller driven by the transmission shaft, further pushes the wastewater within the connecting chamber upwards, facilitating its discharge from the low-pressure outlet. The flow of wastewater within the flow chamber also carries away metal shavings or impurities adhering to the outer surface of the inner filter screen after filtration, ensuring its discharge through the low-pressure outlet. This effectively cleans the inner filter screen, preventing dirt from easily accumulating on its outer surface.

To more clearly illustrate this invention, a preferred embodiment is described in detail below with reference to the accompanying drawings. Referring to Figures 1 to 3, a preferred embodiment of this invention, a centrifugal high-pressure sludge pump 100, has an axial length L extending in the vertical direction and includes a fixed disc 10, a swashplate axial piston pump 20, a filter assembly 30, a casing assembly 40, a motor 50, and an impeller assembly 60, wherein:

Please refer to Figures 4 to 7. The fixed plate 10 is a disc body with a motor seat 12 on the upper side and a plunger pump seat 14 on the lower side. An upper annular portion 141 is connected to the outer periphery of the plunger pump seat 14, and a fixing ring 142 is connected to the outer periphery of the upper annular portion 141. A plurality of fixing holes 143 are formed around the fixing ring 142. The fixed plate 10 has an upper shaft hole L1 in the center, which passes through the center of the motor seat 12 and the center of the plunger pump seat 14 along the axial direction L.

The fixed plate 10 has a high-pressure flow channel 16 and a low-pressure flow channel 18. The high-pressure flow channel 16 has two ends, one end forming a high-pressure outlet 161 around the fixed plate 10, and the other end forming a high-pressure inlet 162 on one side below the plunger pump seat 14. The low-pressure flow channel 18 has two ends, one end forming a low-pressure outlet 181 around the fixed plate 10, and the other end forming a low-pressure inlet 182 on the underside of the upper annular portion 141. A groove 19 is formed on the other side below the plunger pump seat 14.

Please refer to Figures 3 to 4 and Figures 6 to 7. The swashplate axial piston pump 20 has a distribution plate 22 and a pump cover 24 on each of the upper and lower sides along the axial direction L. The distribution plate 22 is fixed to the lower side of the piston pump seat 14, thereby connecting the swashplate axial piston pump 20 to the lower side of the piston pump seat 14. At least one pressure port 221 and at least one suction port 222 are formed on each side of the distribution plate 22. In this preferred embodiment, the at least one pressure port 221 includes a plurality of pressure ports 221 that lead to the high-pressure inlet 162; the at least one suction port 222 includes a plurality of suction ports 222 that communicate with the inside of the groove 19.

A cylinder 26 is disposed close to the lower part of the distribution plate 22. The cylinder 26 can rotate about the axis of rotation L. The peripheral part of the cylinder 26 has a plurality of plunger holes 261. A portion of the plunger holes 261 on one side of the cylinder 26 communicates with the liquid pressure ports 221, and another portion of the plunger holes 261 on the other side of the cylinder 26 communicates with the liquid suction ports 222. A axial through hole L2 is formed in the middle part of the cylinder 26 along the axis L, and an internal tooth ring L21 is formed on the peripheral wall of the axial through hole L2. A plunger 28 is inserted through each of the plunger holes 261. The lower end of each plunger 28 extends downward through the plunger hole 261 and connects to a slipper 281. The slippers 281 abut against a swashplate 29, which is an annular plate inclined relative to the axial direction L. A pump housing 21 is arranged around the distribution plate 22, the cylinder 26, and the swashplate 29. The pump housing 21 is a cylindrical tube and its upper end is connected to the periphery of the plunger pump seat 14. The pump housing 21 accommodates the distribution plate 22, the cylinder 26, the plungers 28, the slippers 281, and the swashplate 29. The outer side of the groove 19 communicates with the interior of the pump housing 21.

The pump cover 24 has a swashplate seat 241 on its upper side and an inner filter screen seat 242 on its lower side in the middle portion. The swashplate 29 is disposed on the swashplate seat 241, and the lower end of the pump casing 21 is connected to the portion surrounding the swashplate seat 241. The middle portion of the pump cover 24 has a central axial hole L3 and at least one liquid inlet hole 244 in its center and periphery. The central axial hole L3 and the at least one liquid inlet hole 244 penetrate the swashplate seat 241 and the inner filter screen seat 242 along the axial direction L. The upper end of the at least one liquid inlet hole 244 communicates with the interior of the pump casing 21. In this preferred embodiment, the at least one inlet port 244 includes a plurality of inlet ports 244; these inlet ports 244 pass through the interior of the pump housing 21 and the groove 19 to the suction ports 222. The peripheral portion of the pump cover 24 has a lower annular portion 245 that protrudes radially from the pump housing 21, and a through hole 246 is formed between the upper surface of the lower annular portion 245 and the lower surface of the peripheral portion of the inner filter screen holder 242.

Referring to Figures 2 to 4, the filtration assembly 30 includes a slot ring 31, an inner filter screen 32, and a cover 34. The slot ring 31 is a ring and is attached to the periphery of the inner filter screen holder 242. A recess 311 is formed by recessing the slot ring 31 inwards around the lower end of the connecting hole 246 to prevent the slot ring 31 from covering the lower end of the connecting hole 246. The slot ring 31 also surrounds the lower ends of the liquid inlet holes 244 to prevent them from being covered. A slot 312, which is a circular groove, is formed on the underside of the slot ring 31.

Referring to Figures 2, 4, and 6, the inner filter 32 is a tubular mesh with sufficient filtration precision to filter fine metal shavings and other impurities generated during machine tool cutting. The upper end of the inner filter 32 is inserted into the slot 312 for fixation, so that the inner filter 32 is connected to the inner filter holder 242 through the slot ring 31. The cover 34 is connected to the lower end of the inner filter 32 and has a lower shaft hole L4 in the center. A filtration chamber S is formed between the pump cover 24, the seal 34 and the inner filter screen 32. The filtration chamber S is connected to the lower end of the liquid inlet holes 244, so that the liquid can pass through the inner filter screen 32 into the filtration chamber S, and then flow through the liquid inlet holes 244 to the inside of the pump housing 21 for the swashplate axial plunger pump 20 to draw.

Please refer to Figures 2 to 4 and Figure 6. The shell assembly 40 includes an upper shell 42, a lower shell 44, a base plate 46, a bottom plate 48, and a primary filter screen 49. The upper casing 42 is a tube and is wrapped around the pump casing 21. The upper end of the upper casing 42 is connected to the periphery of the upper annular portion 141, and the lower end of the upper casing 42 is connected to the periphery of the lower annular portion 245. A connecting cavity S1 is formed between the upper annular portion 141, the lower annular portion 245, the pump casing 21, and the upper casing 42. The connecting cavity S1 is an annular space. The upper side of the connecting cavity S1 communicates with the low-pressure inlet 182, and the lower side of the connecting cavity S1 communicates with the connecting hole 246.

The lower casing 44 is a tube body and is wrapped around the inner filter screen 32. The upper end of the lower casing 44 is connected to the periphery of the inner filter screen holder 242. The base 46 is located directly below the cover 34 and is connected to the lower end of the lower casing 44 with its periphery. The base 46 has a liquid inlet 461 in the center and an annular cone 462 is formed on the upper surface of the base 46. The liquid inlet 461 passes through the middle of the annular cone 462. A flow chamber S2 is formed between the pump cover 24, the chassis 46, the lower casing 44 and the inner filter screen 32. The lower side of the flow chamber S2 communicates with the liquid inlet 461. The flow chamber S2 is an annular space and its upper side communicates with the connecting hole 246. The two ends of the connecting hole 246 are respectively connected to the connecting chamber S1 and the flow chamber S2. The flow chamber S2 leads to the low-pressure inlet 182 through the connecting hole 246 and the connecting chamber S1.

The base plate 48 is located directly below the chassis 46. The primary filter 49 is a circular mesh with its upper and lower ends connected to the periphery of the chassis 46 and the periphery of the base plate 48, respectively. The filtration accuracy of the inner filter 32 is higher than that of the primary filter 49. The primary filter 49 is used to initially filter out impurities such as metal shavings that are relatively large.

Please refer to Figures 2, 3, and 6 to 7. The motor 50 can be a DC motor, a frequency converter motor, a stepper motor, or a servo motor, etc., which can change the speed as needed. In this preferred embodiment, the motor 50 is a frequency converter motor and is coupled to the motor base 12 of the fixed plate 10. The motor 50 has a transmission shaft 52. In this preferred embodiment, the axial direction L of the centrifugal high-pressure sewage pump 100 is defined by the axis of the transmission shaft 52. The transmission shaft 52 passes sequentially downwards along the axial direction L through the upper shaft hole L1, the shaft through hole L2, the middle shaft hole L3, and the lower shaft hole L4. The transmission shaft 52, in conjunction with the cylinder body 26, forms an external gear ring 521 on its peripheral wall. This external gear ring 521 meshes with the internal gear ring L21 of the cylinder body 26, thereby enabling the transmission... The shaft 52 is connected to the swashplate axial piston pump 20 and drives the swashplate axial piston pump 20 to operate. The speed of the motor 50 is proportional to the pressure of the liquid drawn and pressurized by the swashplate axial piston pump 20 driven by the motor 50. The lower end of the transmission shaft 52 extends between the cover 34 and the chassis 46.

Referring to Figures 2 and 6 to 7, the impeller assembly 60 includes a centrifugal impeller 62 and a turbine impeller 64. The centrifugal impeller 62 is centrally coupled to the lower end of the transmission shaft 52, and the centrifugal impeller 62 is located between the cover 34 and the chassis 46. Specifically, the centrifugal impeller 62 has a blade disk 621, the center of which is connected to the lower end of the transmission shaft 52. The liquid inlet 461 is located directly below the middle part of the blade disk 621. Multiple blades 622 are connected in a circumferential arrangement around the blade disk 621. The lower edges of these blades 622 are inclined near the annular cone surface 462.

When the drive shaft 52 drives the centrifugal impeller 62 to rotate, a negative pressure area is formed in the middle part of the centrifugal impeller 62, so that the inlet 461 can draw liquid from the outside of the primary filter screen 49, such as cutting fluid containing metal shavings in the cutting fluid tank, and enter the flow chamber S2 after preliminary filtration by the primary filter screen 49, and make the pressure of the liquid in the flow chamber S2 greater than the pressure of the liquid in the filtration chamber S and the connecting chamber S1. In this way, the liquid entering the flow chamber S2 can flow towards the filtration chamber S, so that the inner filter screen 32 can further filter out impurities such as fine metal filings in the liquid, and the relatively clean liquid after filtration can enter the filtration chamber S.

The liquid entering the filtration chamber S fills the pump housing 21 through the inlet holes 244, allowing the liquid to flow from the groove 19 to the suction ports 222 of the distribution plate 22 for the swashplate axial piston pump 20 to draw and pressurize. When the swashplate axial piston pump 20 draws liquid from the pump housing 21, a negative pressure attraction is generated inside the pump housing 21, drawing the liquid outside the inner filter screen 32 toward the filtration chamber S, and finally into the pump housing 21 for the swashplate axial piston pump 20 to draw. The liquid pressurized by the swashplate axial piston pump 20 will eventually be output at high pressure from the high-pressure outlet 161. The high pressure of the liquid output from the high-pressure outlet 161 comes not only from the high pressurization capacity of the swashplate axial piston pump 20, but also from the fact that when the motor 50 operates at a lower speed, the swashplate axial piston pump 20 pressurizes the liquid at a lower pressure. Therefore, the high pressure of the liquid output from the high-pressure outlet 161 is relative to the low pressure of the liquid output from the low-pressure outlet 181.

In this design, since the liquid entering the swashplate axial piston pump 20 has passed through the primary filter 49 and the internal filter 32 to filter out impurities such as metal shavings, the liquid entering the filtration chamber S, such as cutting fluid, is relatively clean. This protects the internal parts of the swashplate axial piston pump 20 from damage by impurities such as metal shavings, thereby extending the service life of the swashplate axial piston pump 20 and making this design easy to maintain. Because the pressure of the liquid in the flow chamber S2 is greater than that in the connecting chamber S1, the liquid in the flow chamber S2 will also flow upward towards the connecting chamber S1 to some extent. This causes the liquid to flow from the connecting hole 246 and the flow chamber S2 to the low-pressure inlet 182, and finally be discharged outward at low pressure from the low-pressure outlet 181. When this invention is used for pressurized cutting fluid in a machine tool, because the liquid discharged from the low-pressure outlet 181 contains more impurities such as metal shavings, the low-pressure outlet 181 will be connected to an external filtration device. After the external filtration device filters the cutting fluid, it will be circulated back to this invention for pressurized output. At this time, the fixed plate 10 is fixed to the water tank by the bracket, and the lower side of the lower tube shell 44 and the primary filter screen 49 are immersed in the cutting fluid in the water tank.

The turbine impeller 64 includes a blade support plate 641, a blade support 642, multiple inclined blades 643, and multiple helical blades 644. The middle part of the blade support plate 641 is sleeved around the lower end of the transmission shaft 52, and the lower part of the blade support plate 641 contacts the upper part of the centrifugal impeller 62. The centrifugal impeller 62 is screwed to the blade support plate 641, thereby connecting the turbine impeller 64 to the lower end of the transmission shaft 52 and surrounding the inner filter screen 32. The drive shaft 52 can simultaneously drive the swashplate axial piston pump 20, the centrifugal impeller 62, and the turbine impeller 64 to rotate together.

The blade support 642 is tubular and has multiple perforations 6421. The lower end of the blade support 642 is connected to the periphery of the blade support disc 641, such that the blade support 642 is located within the flow cavity S2 and surrounds the inner filter screen 32. The inclined blades 643 are connected to the blade support 642, and the extension direction of the inclined blades 643 is inclined relative to the axial direction L of the transmission shaft 52. The helical blades 644 are connected to the blade support 642, and the extension direction of the helical blades 644 is a helical segment with the axial direction L of the transmission shaft 52 as the center of rotation. Specifically, the blade support 642 includes a plurality of rings 642A spaced apart along the axial direction L of the transmission shaft 52.

In this preferred embodiment, the plurality of rings 642A includes three rings 642A. The lowermost ring 642A is coupled to the periphery of the blade support disk 641, and a plurality of inclined ribs 642B are connected between the rings 642A. The inclined ribs 642B are arranged in a manner that encircles the transmission shaft 52, and the extension direction of each inclined rib 642B is inclined relative to the axial direction L of the transmission shaft 52. Each opening 6421 is formed between two adjacent rings 642A and two adjacent inclined ribs 642B. The inclined blades 643 are respectively connected to the portions of each inclined rib 642B located between two adjacent rings 642A. Each ring 642A, except for the lowermost ring 642A, is connected to a plurality of the spiral blades 644 in a circumferential arrangement.

When the transmission shaft 52 drives the turbine impeller 64 to rotate, it drives the inclined blades 643 and the spiral blades 644 of the turbine impeller 64 to rotate around the transmission shaft 52 as the center of rotation. When the inclined blades 643 and the spiral blades 644 rotate, they can generate an upward thrust, which can further push the liquid in the flow chamber S2 upward. In addition, while the inclined blades 643 and the spiral blades 644 agitate the liquid in the flow chamber S2 and make it flow upward, they also make the liquid swirl.

By means of the rotation of the turbine impeller 64, the liquid flowing upward in the flow chamber S2, propelled by the centrifugal impeller 62, can more smoothly flow from the connecting hole 246 and the flow chamber S2 to the low-pressure inlet 182 for discharge. At the same time, the liquid forced upward and swirling by the turbine impeller 64 flows over the outer surface of the inner filter screen 32, carrying away metal shavings that have been filtered by the inner filter screen 32 and adhered to its outer surface, thus cleaning the inner filter screen 32. In this way, the internal filter 32 is not easily clogged even after filtering metal shavings from the liquid in the filtration chamber S for a long time, which further enables the invention to eliminate the need for frequent disassembly and cleaning of the internal filter 32.

The above description is merely a preferred embodiment of the invention. Any equivalent changes made in accordance with the invention specification and the scope of the patent application should be included within the scope of the invention.

100: Centrifugal high-pressure sludge pump 10: Fixed plate 12: Motor seat 14: Plunger pump seat 141: Upper annular part 142: Fixed ring 143: Fixed hole 16: High-pressure flow channel 161: High-pressure outlet 162: High-pressure inlet 18: Low-pressure flow channel 181: Low-pressure outlet 182: Low-pressure inlet 19: Groove 20: Swashplate axial plunger pump 21 : Pump housing 22: Distribution plate 221: Pressure port 222: Suction port 24: Pump cover 241: Swashplate seat 242: Internal filter screen seat 244: Liquid inlet 245: Lower annular part 246: Connecting hole 26: Cylinder block 261: Plunger hole 28: Plunger 281: Slipper 29: Swashplate 30: Filter assembly 31: Slotted ring 311: Recess 3 12: Slot 32: Internal Filter 34: Cover 40: Shell Assembly 42: Upper Shell 44: Lower Shell 46: Chassis 461: Liquid Inlet 462: Annular Conical Surface 48: Base Plate 49: Primary Filter 50: Motor 52: Drive Shaft 521: External Gear Ring 60: Impeller Assembly 62: Centrifugal Impeller 621: Fan Blade Disc 622: Fan Blade 64: Turbine impeller 641: Blade support plate 642: Blade support 6421: Hollowed-out opening 642A: Ring 642B: Inclined rib 643: Inclined blade 644: Helical blade L: Axial direction L1: Upper shaft hole L2: Shaft through hole L21: Internal gear ring L3: Middle shaft hole L4: Lower shaft hole S: Filter chamber S1: Connecting chamber S2: Flow chamber

Figure 1 is a perspective view of a preferred embodiment of the present invention. Figure 2 is an exploded view of the preferred embodiment of the present invention described above. Figure 3 is an exploded view of the upper half of Figure 2. Figure 4 is a perspective view of Figure 3 from another angle. Figure 5 is a top view of the preferred embodiment of the present invention described above. Figure 6 is a cross-sectional view along direction 6-6 of Figure 5. Figure 7 is a cross-sectional view along direction 7-7 of Figure 5.

100: Centrifugal Sewage High-Pressure Hydraulic Pump

10: Fixed plate

40: Shell assembly

50: Motor

L: Axial direction

Claims (10)

A centrifugal high-pressure hydraulic pump for sewage discharge includes: a fixed plate having an upper shaft bore and a high-pressure outlet and a low-pressure outlet around its periphery; a high-pressure inlet and a low-pressure inlet on the lower side of the fixed plate, the high-pressure inlet leading to the high-pressure outlet and the low-pressure inlet leading to the low-pressure outlet; a swashplate axial piston pump, connected to the fixed plate on its upper side and having at least one pressure port and at least one suction port, the at least one pressure port leading to the high-pressure inlet; a pump cover on the lower side of the swashplate axial piston pump, the pump cover having a central shaft bore and at least one inlet port, the at least one inlet port leading to the at least one suction port; A filtration assembly includes an inner filter screen and a cover; the inner filter screen is a tubular mesh and its upper end is connected to the pump cover, the cover is connected to the lower end of the inner filter screen and has a lower axial hole; a filtration chamber is formed between the pump cover, the cover and the inner filter screen, and the filtration chamber communicates with the at least one liquid inlet. A casing assembly includes a lower casing and a base; the lower casing is fitted around the inner filter screen and its upper end is connected to the pump cover; the base is located directly below the cover and connected to the lower end of the lower casing, and the base has a liquid inlet; a flow chamber is formed between the pump cover, the base, the lower casing, and the inner filter screen, and the flow chamber leads to the low-pressure inlet; a motor is connected to the fixed plate and has a drive shaft, the drive shaft sequentially passing through the upper shaft hole, the middle shaft hole, and the lower shaft hole and connected to the swashplate axial piston pump; and A centrifugal impeller is centrally coupled to the lower end of the drive shaft, the centrifugal impeller being positioned between the cover and the chassis. As described in claim 1, the centrifugal high-pressure pump for sewage discharge includes a swashplate axial piston pump with a pump housing. The upper end of the pump housing is connected to the fixed plate, and the lower end of the pump housing is connected to the pump cover. The peripheral portion of the pump cover has a lower annular portion that radially protrudes from the pump housing and has a through hole. The at least one inlet hole communicates with the interior of the pump housing. A groove is formed on the bottom surface of the fixed plate, and the inner side of the groove is connected to the at least one inlet hole. The groove is connected to the inner part of the pump housing, and the outer side of the groove is connected to the inner part of the pump housing. The housing assembly also includes an upper housing, which is wrapped around the pump housing and its upper end is connected to the fixed plate. The lower end of the upper housing is connected to the periphery of the lower annular part. A connecting cavity is formed between the pump housing and the upper housing, which is connected to the low-pressure inlet. The two ends of the connecting hole are respectively connected to the connecting cavity and the flow cavity. As described in claim 2, the centrifugal high-pressure pump for sewage discharge comprises a motor seat and a plunger pump seat on each of the upper and lower sides of the fixed plate. The outer periphery of the plunger pump seat is connected to an upper annular portion. The high-pressure inlet is formed on one side of the plunger pump seat, and the groove is formed on the other side of the plunger pump seat. The low-pressure inlet is formed on the upper annular portion. A swashplate seat is formed on the upper side of the middle portion of the pump cover. The motor is coupled to the motor seat. The upper side of the swashplate axial plunger pump is coupled to the lower side of the plunger pump seat. The upper end of the pump casing is coupled to the periphery of the plunger pump seat, and the lower end of the pump casing is coupled to the periphery of the swashplate seat. The upper end of the upper casing is coupled to the periphery of the upper annular portion. As described in claim 3, the centrifugal high-pressure pump for sewage discharge includes an inner filter holder formed on the lower side of the middle portion of the pump cover; a connecting hole is formed between the upper surface of the lower annular portion and the lower surface of the peripheral portion of the inner filter holder; a slot ring is attached to the peripheral portion of the inner filter holder, the slot ring is wrapped around the lower end of the at least one inlet hole, and the lower end of the connecting hole is recessed inward around the periphery of the slot ring to form a recess, the space in the recess leading to the connecting hole; the slot ring has a slot; the upper end of the inner filter is inserted into the slot for fixation; and the upper end of the lower casing is attached to the peripheral portion of the inner filter holder. The centrifugal high-pressure pump for sewage discharge as described in claim 1, wherein a turbine impeller is coupled to the lower end of the drive shaft, the turbine impeller being located within the flow chamber and surrounding the internal filter screen. The centrifugal high-pressure pump for sewage discharge as described in claim 5, wherein the turbine impeller includes a blade support disc and a blade support, the blade support disc being sleeved around the lower end of the transmission shaft, the lower part of the blade support disc contacting the upper part of the centrifugal impeller, and the centrifugal impeller being coupled to the blade support disc; the blade support is tubular and has multiple perforations, the lower end of the blade support being coupled to the periphery of the blade support disc, such that the blade support is located within the flow chamber and surrounds the inner filter screen, and multiple inclined blades are coupled to the blade support, the extension direction of which is inclined relative to the axial direction of the transmission shaft. As described in claim 6, the centrifugal high-pressure sewage pump comprises a plurality of helical blades integrated into the blade support, the helical blades extending in a helical line segment with the axial direction of the transmission shaft as the center of rotation; the blade support includes a plurality of rings spaced apart along the axial direction of the transmission shaft, wherein the lowermost ring is joined to the periphery of the blade support disc, and a plurality of inclined ribs connect the rings. The ribs are arranged in a ring around the transmission shaft, and the extension direction of each inclined rib is inclined relative to the axial direction of the transmission shaft; each opening is formed between two adjacent rings and two adjacent inclined ribs; each ring except the lowermost ring is connected to a plurality of the spiral blades in a ring arrangement; each inclined rib is connected to one of the inclined blades at the portion between two adjacent rings. The centrifugal high-pressure pump for sewage discharge as described in claim 1, wherein an annular cone is formed on the upper surface of the chassis, and the inlet penetrates the middle of the annular cone; the centrifugal impeller has a vane disk, the center of which is connected to the lower end of the transmission shaft, the inlet is located directly below the middle portion of the vane disk, and multiple vanes are connected in a circumferential arrangement around the vane disk, with the lower edge of each vane inclined near the annular cone. The centrifugal high-pressure pump for sewage discharge as described in claim 1, wherein a base plate is provided directly below the chassis, and a primary filter is connected between the periphery of the chassis and the periphery of the base plate. The centrifugal high-pressure sewage pump as described in claim 9, wherein the motor is a DC motor, a variable frequency motor, a stepper motor, or a servo motor; and the filtration accuracy of the internal filter is higher than that of the primary filter.