Digital variable plunger pump unit and radial plunger pump

Abstract

The invention provides a digital variable plunger pump unit and a radial plunger pump, and belongs to the technical field of plunger pumps. The digital variable plunger pump unit comprises a pump body and a plunger, a plunger hole and a pumping channel are arranged in the pump body, an inlet and an outlet of the pumping channel are provided with a suction valve and a flow control valve respectively, the flow control valve comprises a valve seat and a valve cavity arranged in the valve seat, and the valve seat is provided with a valve inlet, a valve outlet and a pressure relief opening which are communicated with the valve cavity. The flow control valve further comprises a jacking structure which elastically abuts against and seals the pressure relief opening from the outer side, and a piezoelectric ceramic piece which is used for lifting the jacking structure through extension to open the pressure relief opening at the high level is arranged between the valve seat and the jacking structure. The radial plunger pump comprises the plunger pump unit. According to the plunger pump unit, the flow control valve is arranged at the outlet of the plunger pump unit, so that accurate control over the output flow of the single plunger pump unit is achieved, and different use requirements are met.

Description

Technical Field

[0001] This invention belongs to the field of plunger pump technology, and in particular relates to a digital variable plunger pump unit and a radial plunger pump. Background Technology

[0002] Ultra-high pressure hydraulic technology requires pressurizing liquids to over 100MPa. Plunger hydraulic pumps, due to their high working pressure and high efficiency, are typically used as ultra-high pressure power sources, while radial piston pumps, due to their strong drive mechanism load-bearing capacity, are more suitable for ultra-high pressure working scenarios.

[0003] The general structure of a radial piston pump can be referred to in Chinese invention patent application CN107939628A, which discloses a multi-head radial piston pump. The multi-head radial piston pump includes a pump body, piston mechanisms, and eccentric wheels. The piston mechanisms are installed at intervals in the pump body along the circumferential direction. The pump body is provided with a drive shaft, and the eccentric wheels are mounted on the drive shaft. The eccentric wheels are rotatably installed between the piston mechanisms. When the eccentric wheels rotate, the piston mechanisms move back and forth in the radial direction successively, thereby successively sucking up and discharging the working medium.

[0004] In existing technologies, the output flow rate of each plunger assembly (i.e., plunger pump unit) is fixed within one working cycle, and the overall output flow rate of the radial plunger pump is also fixed, making it difficult to adapt to different working requirements. Moreover, the output pressure of a single plunger assembly varies pulsatingly. Although the pulsation of output pressure can be alleviated by arranging multiple plunger assemblies circumferentially and alternating their output, the limited space in the circumferential direction and the limited number of plunger assemblies make it difficult to further improve the stability of the overall output pressure of the current radial plunger pump. Summary of the Invention

[0005] The purpose of this invention is to provide a digital variable displacement piston pump unit to solve the technical problems of existing piston pumps having difficulty in adjusting output flow and having unstable output pressure.

[0006] Another object of the present invention is to provide a radial piston pump to solve the above-mentioned technical problems.

[0007] To achieve the above objectives, the technical solution of the digital variable piston pump unit provided by this invention is as follows: A digital variable displacement piston pump unit includes a pump body and a piston. The pump body has a plug hole for reciprocating motion of the piston and a pumping channel communicating with the plug hole in the middle. The inlet and outlet of the pumping channel are respectively provided with a suction valve and a flow control valve. The flow control valve includes a valve seat and a valve cavity disposed in the valve seat. The valve seat is provided with a valve inlet, a valve outlet and a pressure relief port communicating with the valve cavity. A valve ball is disposed in the valve cavity, which is pressed against and closes the valve inlet by an elastic element. The flow control valve also includes a top pressure structure that elastically presses against and closes the pressure relief port from the outside. A piezoelectric ceramic element is disposed between the valve seat and the top pressure structure for extending to lift the top pressure structure to open the pressure relief port when the voltage is high.

[0008] As a further improvement, the valve seat has a pressure relief port at one end connected to the valve body, and the pressure-relief structure includes a compression spring nested inside and outside the piezoelectric ceramic component, a force transmission component connected between the end of the piezoelectric ceramic component away from the valve seat and the end of the compression spring near the valve seat, and a pressure relief sealing structure pressed by the force transmission component at the pressure relief port.

[0009] As a further improvement, the valve body is a cup-shaped structure with the opening connected to the valve seat and an opening at the bottom. The top pressure structure and the piezoelectric ceramic component are both located inside the valve body. The force transmission component is sleeve-shaped and has abutment parts at both ends for abutting the piezoelectric ceramic component and the compression spring, respectively. One of the piezoelectric ceramic component and the compression spring is located inside the force transmission component and the other is located outside the force transmission component.

[0010] As a further improvement, the piezoelectric ceramic component is located inside the force transmission component, and the compression spring is located outside the force transmission component. The force transmission component is a cup-shaped structure with its opening facing the valve seat. The opening of the force transmission component is provided with an outwardly turned flange for abutting against the compression spring. The bottom wall of the force transmission component is used to abut against the piezoelectric ceramic component. The flange and the bottom wall respectively constitute the abutting part. An opening for the working medium to flow through is provided on the bottom wall.

[0011] As a further improvement, the pressure relief sealing structure includes a push rod and a sealing ball. One end of the push rod is pressed against or connected to the force transmission component, and the other end of the push rod is provided with a recess for the sealing ball to be inserted. The end of the pressure relief port facing out of the valve cavity is provided with a trumpet-shaped guide structure for guiding the sealing ball to press and close the pressure relief port.

[0012] As a further improvement, the pressure relief sealing structure includes a push rod, one end of which is pressed against or connected to the force transmission component, and the other end of the push rod is provided with a spherical surface. The end of the pressure relief port facing out of the valve cavity is provided with a trumpet-shaped guiding structure for guiding the spherical surface of the push rod to press against and seal the pressure relief port.

[0013] As a further improvement, the valve seat includes a seat body and a base mounted on the seat body for receiving the piezoelectric ceramic component. A position adjustment structure is provided between the base and the seat body for adjusting the position of the base along the extension and retraction direction of the piezoelectric ceramic component.

[0014] As a further improvement, a hollow connecting column is provided at the pressure relief port on the main body of the seat. The outer circumferential surface of the connecting column is provided with external threads. The base is a ring-shaped structure and its inner circumferential surface is provided with internal threads for threaded connection with the connecting column. The threaded engagement structure between the connecting column and the base constitutes the position adjustment structure.

[0015] The beneficial effects are as follows: The digital variable displacement piston pump unit provided by this invention is an improvement on the prior art. This digital variable displacement piston pump unit replaces the ordinary one-way valve at its outlet with a flow control valve that can control the flow rate, thereby achieving precise control of the output flow rate of a single piston pump unit to adapt to different application requirements; moreover, during use, the flow control valves on each piston pump unit can be controlled separately according to the rotation angle information of the shaft, thereby regulating the output flow rate and pressure pulsation, and improving the pressure output quality of the radial piston pump.

[0016] To achieve the above objectives, the technical solution of the radial piston pump provided by this invention is as follows: A radial plunger pump includes a housing, a rotating shaft, and plunger pump units arranged around the rotating shaft. The rotating shaft has an eccentric structure for pushing each plunger of the plunger pump unit. Each plunger pump unit includes a pump body and plungers. The pump body has a plug hole for reciprocating motion of the plungers and a pumping channel communicating with the plug hole in the middle. The inlet and outlet of the pumping channel are respectively provided with a suction valve and a flow control valve. The flow control valve includes a valve seat and a valve cavity disposed in the valve seat. The valve seat has a valve inlet, a valve outlet, and a pressure relief port communicating with the valve cavity. The valve cavity has a valve ball that is pressed against and closes the valve inlet by an elastic element. The flow control valve also includes a top pressure structure that elastically presses against and closes the pressure relief port from the outside. A piezoelectric ceramic element is disposed between the valve seat and the top pressure structure for extending to lift the top pressure structure to open the pressure relief port when the voltage is high.

[0017] As a further improvement, the valve seat has a pressure relief port at one end connected to the valve body, and the pressure-relief structure includes a compression spring nested inside and outside the piezoelectric ceramic component, a force transmission component connected between the end of the piezoelectric ceramic component away from the valve seat and the end of the compression spring near the valve seat, and a pressure relief sealing structure pressed by the force transmission component at the pressure relief port.

[0018] As a further improvement, the valve body is a cup-shaped structure with the opening connected to the valve seat and an opening at the bottom. The top pressure structure and the piezoelectric ceramic component are both located inside the valve body. The force transmission component is sleeve-shaped and has abutment parts at both ends for abutting the piezoelectric ceramic component and the compression spring, respectively. One of the piezoelectric ceramic component and the compression spring is located inside the force transmission component and the other is located outside the force transmission component.

[0019] As a further improvement, the piezoelectric ceramic component is located inside the force transmission component, and the compression spring is located outside the force transmission component. The force transmission component is a cup-shaped structure with its opening facing the valve seat. The opening of the force transmission component is provided with an outwardly turned flange for abutting against the compression spring. The bottom wall of the force transmission component is used to abut against the piezoelectric ceramic component. The flange and the bottom wall respectively constitute the abutting part. An opening for the working medium to flow through is provided on the bottom wall.

[0020] As a further improvement, the pressure relief sealing structure includes a push rod and a sealing ball. One end of the push rod is pressed against or connected to the force transmission component, and the other end of the push rod is provided with a recess for the sealing ball to be inserted. The end of the pressure relief port facing out of the valve cavity is provided with a trumpet-shaped guide structure for guiding the sealing ball to press and close the pressure relief port.

[0021] As a further improvement, the pressure relief sealing structure includes a push rod, one end of which is pressed against or connected to the force transmission component, and the other end of the push rod is provided with a spherical surface. The end of the pressure relief port facing out of the valve cavity is provided with a trumpet-shaped guiding structure for guiding the spherical surface of the push rod to press against and seal the pressure relief port.

[0022] As a further improvement, the valve seat includes a seat body and a base mounted on the seat body for receiving the piezoelectric ceramic component. A position adjustment structure is provided between the base and the seat body for adjusting the position of the base along the extension and retraction direction of the piezoelectric ceramic component.

[0023] As a further improvement, a hollow connecting column is provided at the pressure relief port on the main body of the seat. The outer circumferential surface of the connecting column is provided with external threads. The base is a ring-shaped structure and its inner circumferential surface is provided with internal threads for threaded connection with the connecting column. The threaded engagement structure between the connecting column and the base constitutes the position adjustment structure.

[0024] As a further improvement, the plunger pump units are arranged in groups, with each plunger pump unit in each group being circumferentially distributed and each plunger pump unit group being axially distributed. At least two groups of plunger pump units are arranged circumferentially staggered to alternately output the working medium.

[0025] The beneficial effects are as follows: The radial piston pump provided by this invention is an improvement on the prior art. The piston pump unit of this radial piston pump replaces the ordinary one-way valve at its outlet with a flow control valve that can control the flow rate, thereby achieving precise control of the output flow rate of a single piston pump unit to adapt to different application requirements; moreover, during use, the flow control valves on each piston pump unit can be controlled separately according to the rotation angle information of the shaft, thereby regulating the output flow rate and pressure pulsation, and improving the pressure output quality of the radial piston pump. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of the radial plunger pump in this invention; Figure 2This is a schematic diagram of the radial plunger pump of the present invention after removing part of the outer shell in Embodiment 1. Figure 3 This is a schematic diagram of the motor structure in Embodiment 1 of the radial piston pump of the present invention; Figure 4 This is a schematic diagram of the front end cover in Embodiment 1 of the radial plunger pump of the present invention; Figure 5 This is a cross-sectional view of the front end cover in Embodiment 1 of the radial plunger pump of the present invention; Figure 6 This is a schematic diagram of the rear end cover in Embodiment 1 of the radial plunger pump of the present invention; Figure 7 This is a cross-sectional view of the rear end cover in Embodiment 1 of the radial plunger pump of the present invention; Figure 8 This is a schematic diagram of the diaphragm structure in Embodiment 1 of the radial plunger pump of the present invention; Figure 9 This is a cross-sectional view of the diaphragm in Embodiment 1 of the radial piston pump of the present invention; Figure 10 This is a schematic diagram of the connecting ring structure in Embodiment 1 of the radial plunger pump of the present invention; Figure 11 This is a cross-sectional view of the connecting ring in Embodiment 1 of the radial piston pump of the present invention; Figure 12 This is a schematic diagram of the piston pump unit in Embodiment 1 of the radial piston pump of the present invention; Figure 13 This is a schematic diagram of the base structure in Embodiment 1 of the radial plunger pump of the present invention; Figure 14 This is a schematic diagram of the plunger structure in Embodiment 1 of the radial plunger pump of the present invention; Figure 15 This is a schematic diagram of the flow control valve in Embodiment 1 of the radial plunger pump of the present invention; Figure 16 This is a schematic diagram of the flow control valve in Embodiment 2 of the radial plunger pump of the present invention; Figure 17 This is a schematic diagram of the flow control valve in Embodiment 3 of the radial piston pump of the present invention.

[0027] Explanation of reference numerals in the attached figures: 1. Outer shell; 11. Front cover; 12. Rear cover; 13. Partition; 131. Recess; 14. Connecting ring; 141. Sealing groove; 15. Connecting hole; 16. Pump inlet; 17. Pump outlet; 18. Combining channel; 181. Circular channel; 182. Connecting channel; 183. Pump outlet channel; 184. Merging channel; 2. Rotating shaft; 21. Distribution channel; 3. Plunger pump unit; 31. Pump body; 311. Plug hole; 312. Pumping channel; 32. Plunger; 321. Head; 322. Spherical surface; 33. Suction valve; 34. Flow control valve; 341. Valve seat; 342. Valve chamber; 343. 344. Valve inlet; 345. Valve outlet; 346. Pressure relief port; 347. Valve body; 348. Compression spring; 349. Force transmission component; 340. Piezoelectric ceramic component; 3410. Push rod; 3411. Sealing ball; 3412. Guide structure; 3413. Guide hole; 3414. Base support; 3415. Connecting column; 35. Piston spring; 36. Spring seat; 37. Base; 371. Arc-shaped mating surface; 372. Ball socket structure; 4. Eccentric structure; 41. Eccentric shaft section; 42. Bearing structure; 43. Spacer sleeve; 44. Threaded ring; 5. Motor; 6. Shaft seal structure; 7. Support bearing; 8. Encoder. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to the embodiments.

[0029] Specific embodiment 1 of the radial plunger pump provided by the present invention: See appendix Figure 1 and attached Figure 2 The radial piston pump includes a housing 1, a rotating shaft 2, and a piston pump unit 3. The rotating shaft 2 is provided with an eccentric structure 4 for pushing each piston 32 of the piston pump unit 3.

[0030] The outer casing 1 includes a front cover 11 and a rear cover 12 located at its axial ends, and also includes two extension shells disposed between the front cover 11 and the rear cover 12. The front cover 11, the extension shells, and the rear cover 12 are stacked axially. A rotating shaft 2 passes through the inner cavity of the outer casing 1 axially. Both ends of the rotating shaft 2 are rotatably engaged with the front cover 11 and the rear cover 12, respectively. A shaft seal structure 6 is provided between the rotating shaft 2 and the rear cover 12, and a support bearing 7 is provided between the rotating shaft 2 and the front cover 11. See Appendix. Figure 3 In this embodiment, the rotating shaft 2 is the output shaft of the motor 5 configured for the radial piston pump. In other embodiments, the rotating shaft 2 can also be set independently and then connected to the motor 5 through a coupling.

[0031] The expansion shell includes two partitions 13 and three connecting rings 14. The two partitions 13 are arranged axially at intervals, and the three connecting rings 14 are respectively located between the front cover 11 and the adjacent partition 13, between two adjacent partitions 13, and between the rear cover 12 and the adjacent partition 13. The outer contours of the connecting rings 14, partitions 13, front cover 11, and rear cover 12 are similar and the outer contours of each component are aligned. See Appendix. Figure 4 -Appendix Figure 11 Each component of the outer shell 1 has a corresponding connecting hole 15 at its outer contour edge, so that the components of the outer shell 1 can be strung together and fixed together to form a complete outer shell 1 using bolts.

[0032] See appendix Figure 10 and attached Figure 11 Each connecting ring 14 has a sealing groove 141 on its axial end face, and a sealing strip is installed in each sealing groove 141. See Appendix Figure 4 -Appendix Figure 9 The front cover 11, the rear cover 12, and the partition 13 are all provided with recesses 131 at the positions for mating with the connecting ring 14, and the end face of the connecting ring 14 is in close contact with the recesses 131. The recesses 131 facilitate the alignment of the components during installation and also reduce the amount of finishing work on the end faces.

[0033] A central hole is formed in the center of the partition 13, through which the rotating shaft 2 passes. A large space is left between the central hole and the rotating shaft 2 to allow for circumferential flow of the working medium. The portion of the partition 13 located in the inner cavity of the outer shell 1 is the radially inward extension of the extended shell. This portion constitutes the mounting base for mounting the plunger pump unit 3. The plunger pump unit 3 is mounted on the side of the partition 13 opposite to the rear end cover 12 and on the inner side of the rear end cover 12.

[0034] Each plunger pump unit 3 on the same partition 13 or rear end cover 12 belongs to a group, thus there are three groups of plunger pump units 3 in the radial plunger pump of this embodiment. The number of plunger pump units 3 in each group is the same, which is five, and the plunger pump units 3 in each group are evenly spaced in the circumferential direction. In other embodiments, the number of plunger pump units 3 in a group may also be three or seven, and the number of groups of plunger pump units 3 may also be two or four.

[0035] Two adjacent sets of plunger pump units 3 are offset by a certain angle in the circumferential direction. The value of the offset angle is determined according to the actual situation, and ultimately, all sets of plunger pump units 3 need to be offset in the circumferential direction. To make the offset more uniform, the offset angle between two adjacent sets of plunger pump units 3 can be 360° / (the number of plunger pump units 3 in a set * the number of sets of plunger pump units 3). In this embodiment, the offset angle between two adjacent sets of plunger pump units 3 is limited to facilitate installation and arrangement. In other embodiments, a set of plunger pump units 3 can also be offset from another set of non-adjacent plunger pump units 3 according to the above rules to achieve the same effect.

[0036] The rotating shaft 2 has an eccentric shaft section 41, the length of which covers the distribution range of each plunger pump unit 3. Three bearing structures 42 are axially spaced on the eccentric shaft section 41, each separated by a spacer sleeve 43. Each bearing structure 42 and spacer sleeve 43 is pressed and fixed by a threaded ring 44 threaded onto the rotating shaft 2. The three bearing structures 42 correspond to three groups of plunger pump units 3, with the outer circumferential surface of the outer ring of each bearing structure 42 abutting against each plunger pump unit 3 in its corresponding group. When the rotating shaft 2 rotates, the bearing structures 42 sequentially push against each plunger pump unit 3. In this embodiment, the eccentric shaft section 41 and the bearing structures 42 constitute an eccentric structure 4.

[0037] When in use, the working medium output by all plunger pump units 3 is collected together and pumped out as a whole, and the output flow of each group of plunger pump units 3 is superimposed.

[0038] The plunger pump unit 3 can sequentially and alternately output the working medium across groups, thereby further shortening the output pressure pulsation interval of the radial plunger pump and improving the stability of the output pressure. For further explanation in conjunction with this embodiment, please refer to the appendix. Figure 2 Each plunger pump unit 3 is numbered. The plunger pump units 3 installed on the rear end cover 12 are sequentially arranged along the circumference as A1, A2, A3, A4, and A5. The plunger pump units 3 on the partition 13 adjacent to the rear end cover 12 are sequentially arranged along the circumference in the same direction as B1, B2, B3, B4, and B5. The plunger pump units 3 on the partition 13 away from the rear end cover 12 are sequentially arranged along the circumference in the same direction as C1, C2, C3, C4, and C5. A1 and B1 correspond to each other and are offset by a certain angle on the circumference, B1 and C1 correspond to each other and are offset by a certain angle on the circumference, and so on.

[0039] In actual use, the working sequence of each plunger pump unit 3 is A1, B1, C1, A2, B2, C2..., and so on, in a cycle. It can be seen that B1 and C1 are inserted between the working times of A1 and A2, further shortening the working interval of each plunger pump unit 3, thereby making the output pressure pulsation peaks more concentrated and effectively improving the stability of the output pressure.

[0040] The outer casing 1 is provided with a pump inlet 16 and a pump outlet 17. The working medium is drawn into the radial piston pump through the pump inlet 16 and pumped out under pressure through the pump outlet 17. The pump inlet 16 is located at the center of the front cover 11, and the pump outlet 17 is located at the edge of the front cover 11.

[0041] See appendix Figure 3 The rotating shaft 2 is provided with a distribution channel 21 for distributing the working medium to the inner cavity of the housing 1. The distribution channel 21 includes an axially extending section of channel and multiple radially extending sections of channel. The axially extending channel penetrates the end face of the rotating shaft 2 corresponding to the front end cover 11 and forms the inlet of the distribution channel 21, so that the inlet of the distribution channel 21 can be directly connected to the pump inlet 16. The radially extending channels are located at the end of the axially extending channel away from the inlet and are connected to the axially extending channel. The radially extending channels penetrate the outer peripheral surface of the rotating shaft 2 and form the outlet of the distribution channel 21. Each outlet of the distribution channel 21 is located between the end wall of the housing 1 without pump inlet 16 and an adjacent set of plunger pump units 3.

[0042] After the working medium enters the distribution channel 21 from the pump inlet 16, it flows into the inner cavity of the outer shell 1 along the outlet of the distribution channel 21. Since the shaft 2 rotates continuously during operation, the outlet of the distribution channel 21 also rotates continuously, which allows the working medium to flow into the inner cavity of the outer shell 1 more evenly. It also disturbs the working medium in the inner cavity of the outer shell 1, making the flow path of the working medium spiral. This has the effect that the working medium flows more fully in the inner cavity of the outer shell 1, which helps to remove the excess heat generated by friction during the operation of the radial plunger pump.

[0043] The plunger pump unit 3 draws in the working medium from the inner cavity of the housing 1 and then expels it after pressurization. The housing 1 is provided with a collection channel 18 for collecting the working medium output by each plunger pump unit 3. Each inlet of the collection channel 18 is connected to the outlet of each plunger pump unit 3, and the outlet of the collection channel 18 constitutes the pump outlet 17 of the radial plunger pump.

[0044] See appendix Figure 4 -Appendix Figure 11The flow collection channel 18 includes an annular channel 181 disposed in each partition 13 and the rear end cover 12. Each partition 13 and the rear end cover 12 has a radially extending connecting channel 182 at the location where each plunger pump unit 3 is disposed, which communicates with the annular channel 181. The connecting channel 182 is the inlet of the flow collection channel 18 and communicates with the outlet of the corresponding plunger pump unit 3. The flow collection channel 18 also includes a radially extending pump outlet channel 183 disposed in each partition 13 and the rear end cover 12. One end of the pump outlet channel 183 communicates with the annular channel, and the other end communicates with a converging channel 184 that passes through the rear end cover 12, the connecting ring 14, the partition 13, and the front end cover 11 in sequence. The end of the converging channel 184 is located at the front end cover 11 and constitutes the outlet of the flow collection channel 18, and also constitutes the pump outlet 17.

[0045] See appendix Figure 12 The plunger pump unit 3 includes a pump body 31 and a plunger 32. The pump body 31 has a plug hole 311 for the reciprocating motion of the plunger 32 and a pumping channel 312 communicating with the plug hole 311 in the middle. The inlet and outlet of the pumping channel 312 are respectively equipped with a suction valve 33 and a flow control valve 34, both of which are one-way valves for the unidirectional passage of the working medium. When the plunger 32 reciprocates in the plug hole 311, the space in the plug hole 311 and the pumping channel 312 alternately increases and decreases, thereby achieving alternating suction and discharge processes of the working medium.

[0046] The reciprocating motion of the plunger 32 is achieved by the combined action of the eccentric structure 4 and the elastic element in the plunger pump unit 3. The elastic element is located between the end of the plunger 32 outside the pump body 31 and the pump body 31. This elastic element is a plunger spring 35 that is always in a compressed state. The plunger 32 is provided with a spring seat 36 for abutting against the plunger 32. The end of the plunger 32 is provided with a head 321 with a larger diameter, and the head 321 and the spring seat 36 are engaged in an axial stop engagement.

[0047] Each plunger pump unit 3 is equipped with a base 37 for the plunger 32, see Appendix Figure 13 One end of the base 37 is an arc-shaped mating surface 371 for adapting to and abutting against the outer peripheral surface of the bearing structure 42. The other end of the base 37 is provided with a ball-and-socket structure 372. (See attached diagram) Figure 14 The head 321 of the plunger 32 is provided with a spherical surface 322 that mates with the ball-and-socket structure 372. The base 37 improves the stress on the plunger 32, reduces the lateral force on the plunger 32, and thus reduces uneven wear of the plunger 32. In other embodiments, the end face of the head 321 of the plunger 32 can be made into a plane, and this plane can be directly mated to the outer peripheral surface of the bearing structure 42, without the need for the base 37.

[0048] The flow control valve 34 is used to control the flow rate of the working medium expelled by the plunger pump unit 3. It can actively regulate the maximum output pressure of the plunger pump unit 3 during operation. When the output pressure exceeds the value, the flow control valve 34 will discharge the excess working medium into the inner cavity of the housing 1, thereby achieving precise control of the output flow rate and realizing the variable function of the radial plunger pump.

[0049] See appendix Figure 15 The flow control valve 34 includes a valve seat 341, a valve body 346, a pressure-pressing structure, and a piezoelectric ceramic component 349. The valve seat 341 contains a valve cavity 342, and the valve seat 341 has a valve inlet 343, a valve outlet 344, and a pressure relief port 345 communicating with the valve cavity 342. A valve ball is disposed within the valve cavity 342, which is pressed against and closes the valve inlet 343 by an elastic element, specifically an internal valve spring. The valve body 346 is connected to the end of the valve seat 341 where the pressure relief port 345 is located. The pressure-pressing structure and the piezoelectric ceramic component 349 are both located within the valve body 346. The pressure-pressing structure elastically presses against and closes the pressure relief port 345 from the outside, and the piezoelectric ceramic component 349 extends to lift the pressure-pressing structure and open the pressure relief port 345 when a high-level voltage is applied.

[0050] The valve housing 346 is a cup-shaped structure with its opening connected to the valve seat 341 and an opening at the bottom. The pressure-relief structure includes a compression spring 347, a force transmission element 348, and a pressure relief sealing structure. The force transmission element 348 is a cup-shaped structure with its opening facing the valve seat 341. An opening for the working medium to flow through is provided on the bottom wall of the force transmission element 348. The compression spring 347 is fitted around the force transmission element 348 and located in the annular space between the force transmission element 348 and the valve housing 346. The opening of the force transmission element 348 has an outwardly flared flange for abutting against the compression spring 347. One end of the compression spring 347 abuts against the flange, and the other end abuts against the bottom wall of the valve housing 346. The bottom wall of the force transmission element 348 is pressed against the pressure relief sealing structure, and the pressure relief sealing structure is pressed against the pressure relief port 345 by the force transmission element 348.

[0051] The piezoelectric ceramic component 349 is a tubular structure, located inside the force transmission component 348. One end of the piezoelectric ceramic component 349 abuts against the valve seat 341, and the other end abuts against the bottom wall of the force transmission component 348. At a high voltage level, the piezoelectric ceramic component 349 can axially extend to overcome the elastic force of the compression spring 347 and push the force transmission component 348. After the force transmission component 348 is pushed and undergoes axial displacement, it no longer applies pressure to the pressure relief sealing structure. At this time, the pressure-relief structure is lifted, and the pressure relief sealing structure opens the pressure relief port 345. At a low voltage level, the piezoelectric ceramic component 349 returns to its original length, and the elastic force of the compression spring 347 causes the force transmission component 348 to move in the opposite direction, thereby pressing the pressure relief sealing structure back onto the pressure relief port 345, closing the pressure relief port 345. The nested arrangement of the piezoelectric ceramic component 349 and the compression spring 347 makes the overall mechanism more compact and saves space.

[0052] The pressure relief sealing structure includes a push rod 3410 and a sealing ball 3411. One end of the push rod 3410 is pressed against the bottom wall of the force transmission component 348, and the other end of the push rod 3410 is pressed against the sealing ball 3411. The sealing ball 3411 is pressed against the end of the pressure relief port 345 facing out of the valve chamber 342. The sealing ball 3411 has the same shape in all directions, so using the sealing ball 3411 to seal the pressure relief port 345 can ensure the reliability of the sealing of the pressure relief port 345.

[0053] A smaller opening than the push rod 3410 is provided on the bottom wall of the force transmission component 348 at a position corresponding to the push rod 3410. A spherical surface is provided at the corresponding end of the push rod 3410 to improve the stress distribution on the push rod 3410. The end of the push rod 3410 used to press the sealing ball 3411 has a recess for the sealing ball 3411 to be engaged, thereby limiting the sealing ball 3411 and ensuring good stability of the sealing ball 3411 under pressure. The end of the pressure relief port 345 facing out of the valve cavity 342 has a trumpet-shaped guide structure 3412 for guiding the sealing ball 3411. Guided by the guide structure 3412, the sealing ball 3411 can automatically roll to the pressure relief port 345, thereby pressing and sealing the pressure relief port 345.

[0054] A guide hole 3413 is provided on the valve seat 341 at the end of the pressure relief port 345 facing the valve cavity 342. The push rod 3410 passes through the guide hole 3413. The inner wall of the guide hole 3413, which is used to guide the push rod 3410, is provided with an axially extending flow groove so that the working medium can flow out from the flow groove when the pressure is relieved.

[0055] To facilitate manufacturing and enable more functions, the valve seat 341 is designed as a split structure in this embodiment. Specifically, the valve seat 341 includes a seat body and a base 3414 disposed on the seat body for receiving the piezoelectric ceramic component 349. A position adjustment structure is provided between the base 3414 and the seat body for adjusting the position of the base 3414 along the extension and retraction direction of the piezoelectric ceramic component 349.

[0056] Because the deformation of the piezoelectric ceramic component 349 is small, assembly errors must be strictly controlled during assembly to prevent it from being loose after assembly. This would result in the piezoelectric ceramic component 349 being insufficient to lift the top pressure structure after elongation. For this purpose, the piezoelectric ceramic component 349, after assembly, needs to be able to abut against the force transmission component 348 without affecting the clamping of the top rod 3410. However, due to manufacturing and assembly errors, this objective is difficult to achieve if directly assembled. In this embodiment, the position of the base support 3414 can be adjusted using a position adjustment structure according to the actual situation of each plunger pump unit 3, thereby achieving the above objective. Of course, if the machining and assembly accuracy meet the usage requirements, the base support 3414 can be omitted, allowing the piezoelectric ceramic to directly abut against the main body.

[0057] The position adjustment structure includes a connecting column 3415 integrally extended axially from the guide hole 3413 on the valve seat 341, and an external thread on the outer circumferential surface of the connecting column 3415. The connecting column 3415 is a hollow tube, and the push rod 3410 passes through the connecting column 3415. A certain gap is left between the connecting column 3415 and the push rod 3410 to allow the working medium to flow. The base 3414 is an annular structure. The position adjustment structure also includes an internal thread on the inner circumferential surface of the base 3414 for threaded connection with the connecting column 3415. The axial position of the base 3414 can be changed by screwing the base 3414.

[0058] The radial piston pump is equipped with an encoder 8 on the motor 5, which can monitor the rotation angle of the shaft 2 in real time. When the shaft 2 rotates to a certain angle, causing a piston 32 pump body 31 unit to switch from sucking in the working medium to discharging the working medium, the controller sends a command to start the flow control valve 34, inputting a PWM (pulse width modulation) voltage signal to the piezoelectric ceramic component 349, controlling the extension and shortening of the piezoelectric ceramic component 349, thereby controlling the displacement of the force transmission component 348, the push rod 3410 and the sealing ball 3411, and finally achieving the purpose of controlling the contact and separation of the sealing ball 3411 and the pressure relief port 345.

[0059] When the input signal is low, the sealing ball 3411 is pressed against the pressure relief port 345, closing the pressure relief port 345. The working medium in the valve chamber 342 flows out from the valve outlet 344 and enters the manifold 18. When the input signal is high, the sealing ball 3411 is released, and the working medium in the valve chamber 342 is discharged from the pressure relief port 345, returning to the inner cavity of the radial plunger pump housing 1 through the force transmission element 348 and the opening on the valve housing 346. This allows control of the output flow of a single plunger pump body 31 unit to adapt to different usage requirements. At the same time, the flow control valves 34 on each plunger pump unit 3 can be controlled according to the rotation angle information of the shaft 2, thereby regulating the output flow and pressure pulsation and improving the pressure output quality of the radial plunger pump.

[0060] Piezoelectric ceramics have the advantages of fast response speed and high stiffness. Therefore, the flow control valve 34 uses the piezoelectric ceramic component 349 for regulation operation, which can meet the high frequency response action requirements of the flow control valve 34.

[0061] Specific embodiment 2 of the radial plunger pump provided by the present invention: This implementation method is based on implementation method 1, and the difference between it and implementation method 1 is as follows (see Appendix). Figure 16 In this embodiment, the opening of the force transmission member 348 faces away from the valve seat 341, the piezoelectric ceramic member 349 is located on the outside of the force transmission member 348, and the compression spring 347 is located on the inside of the force transmission member 348. In this embodiment, the length of the push rod 3410 is shorter than that in embodiment 1.

[0062] The position adjustment structure can be similar to that in embodiment 1, that is, a hollow connecting post 3415 is integrally provided on the seat body of valve seat 341, so that the base support 3414 is threadedly connected to the connecting post 3415. In different embodiments, the base support 3414 can be sleeved on the outside of the connecting post 3415 and the connecting post 3415 is connected to the base support 3414 through external threads, or the base support 3414 can be set inside the connecting post 3415 and the connecting post 3415 is connected to the base support 3414 through internal threads.

[0063] In other embodiments, the position adjustment structure may also be at least three threaded pins rotatably mounted on the valve seat 341. Connecting ears are provided on the inner or outer edge of the base 3414 and threaded holes that are threaded to engage with the threaded pins are provided on the connecting ears. Thus, the position of the base 3414 can also be adjusted by turning the threaded pins.

[0064] Specific embodiment 3 of the radial plunger pump provided by the present invention: This implementation method is based on implementation method 1, and the difference between it and implementation method 1 is as follows (see Appendix). Figure 17 In this embodiment, the force transmission component 348 is relatively large. The force transmission component 348 is sleeved outside the valve housing 346. The compression spring 347 is disposed in the annular space between the force transmission component 348 and the valve housing 346. The valve housing 346 is a cylindrical structure with both ends open in the axial direction. The piezoelectric ceramic component 349 is disposed inside the valve housing 346 and still abuts against the bottom wall of the force transmission component 348.

[0065] Specific embodiment 4 of the radial plunger pump provided by the present invention: This embodiment is based on embodiment 1. The difference between this embodiment and embodiment 1 is that the force transmission component in this embodiment is a sheet-like structure. The piezoelectric ceramic component, the force transmission component and the compression spring are arranged in sequence along the circumference inside the valve body. This can also achieve the same function, but the flow control valve occupies a larger space and is suitable for situations where the number of plunger pump units in each group is small, such as three.

[0066] Specific embodiment 5 of the radial plunger pump provided by the present invention: This embodiment is based on embodiment 1. The difference between this embodiment and embodiment 1 is that the pressure relief sealing structure in this embodiment only includes a push rod. One end of the push rod is pressed against the force transmission member, and the other end of the push rod is provided with a spherical surface so that the push rod can be pressed against the pressure relief port under the guidance of the guide structure.

[0067] Specific embodiment 6 of the radial plunger pump provided by the present invention: This embodiment is based on embodiment 1. The difference between this embodiment and embodiment 1 is that the push rod is fixedly connected to the force transmission component, and the push rod can move together with the force transmission component when the force transmission component moves.

[0068] Specific embodiment 7 of the radial plunger pump provided by the present invention: This embodiment is based on embodiment 1. The difference between this embodiment and embodiment 1 is that the extended shell is a structure that is integrally cast and then machined, and has fewer parts than that in embodiment 1.

[0069] Specific embodiment 8 of the radial plunger pump provided by the present invention: This embodiment is based on embodiment 1. The difference between this embodiment and embodiment 1 is that the expansion shell in this embodiment is composed of multiple units. Each unit includes a partition and a connecting ring. The partition and connecting ring in the same unit can be processed separately and then assembled together, or they can be processed as a single piece. Compared with embodiment 1, the assembly of the expansion shell in this embodiment is more convenient.

[0070] Specific embodiment 9 of the radial plunger pump provided by the present invention: This embodiment is based on Embodiment 1, but differs in that the outer casing in this embodiment includes a rear end cover and a housing. The housing corresponds to the front end cover and connecting ring in Embodiment 1, but is an integrally formed structure. A mounting bracket is fixedly installed on the inner side wall of the housing. Except for the plunger pump unit on the rear end cover, all other plunger pump units are mounted on the mounting bracket. To facilitate the delivery of the working medium, the outlet of each plunger pump unit in this embodiment is connected to a pressure-bearing hose, which replaces the function of the manifold channel.

[0071] Specific embodiment 10 of the radial plunger pump provided by the present invention: This embodiment is based on embodiment 1. The difference between this embodiment and embodiment 1 is that in this embodiment, only one end of the rotating shaft is connected to the rear end cover, and the other end is suspended. In this way, there is no need to set up a flow distribution channel inside the rotating shaft, and the working medium can directly enter the inner cavity of the outer shell through the pump inlet.

[0072] Specific embodiment 11 of the radial plunger pump provided by the present invention: This embodiment is based on embodiment 1. The difference between this embodiment and embodiment 1 is that the distribution channel is also provided with an outlet between two adjacent sets of plunger pump units, and a clearance hole is provided at the corresponding outlet to avoid the outlet.

[0073] Specific embodiment 12 of the radial plunger pump provided by the present invention: This embodiment is based on embodiment 1. The difference between this embodiment and embodiment 1 is that the eccentric shaft segment is not provided on the rotating shaft in this embodiment, but the rotating shaft is provided with a bearing structure with an eccentric inner ring. The eccentric inner ring means that the center hole of the inner ring is set eccentrically. In this way, after the inner ring is connected to the rotating shaft by welding or by key connection, the same purpose as setting an eccentric shaft segment on the rotating shaft can be achieved.

[0074] Specific embodiment 13 of the radial plunger pump provided by the present invention: This embodiment is based on Embodiment 1, but differs in that it does not include a bearing structure. The base of each plunger pump unit directly contacts and slides relative to the eccentric structure. The eccentric structure in this embodiment is an eccentric shaft segment on a rotating shaft or an eccentric cam mounted on a rotating shaft. All parts of the outer circumferential surface of the eccentric shaft segment or eccentric cam are located on the same circumferential surface, meaning that the eccentric shaft segment or eccentric cam is a structure with an unchanged axial profile.

[0075] Specific embodiment 14 of the radial plunger pump provided by the present invention: This embodiment is based on embodiment 1. The difference between this embodiment and embodiment 1 is that the plunger pump units in different groups are circumferentially aligned in this embodiment. An eccentric cam is provided on the rotating shaft at each plunger pump unit group. Adjacent eccentric cams are staggered in the circumferential direction, and the staggering method is the same as the staggering method of the plunger pump units in embodiment 1. The eccentric cams constitute an eccentric structure used to push each plunger pump unit. When used, it can achieve the same effect as embodiment 1.

[0076] Specific embodiment 15 of the radial plunger pump provided by the present invention: This embodiment is based on embodiment 1. The difference between this embodiment and embodiment 1 is that the two sets of plunger pump units set on the partition are not separated, but the plunger pump units on the partition are separated from the plunger pump units on the rear end cover. This also improves the output pressure of the radial plunger pump compared to the prior art.

[0077] Specific embodiments of the digital variable displacement piston pump unit provided by this invention: This digital variable piston pump unit is the piston pump unit in the specific implementation of the radial piston pump described above, and will not be described again.

[0078] It should be noted that this digital variable piston pump unit can be applied to radial piston pumps with multiple sets of piston pump units, or to radial piston pumps with only one set of piston pump units.

[0079] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still make modifications to the technical solutions described in the foregoing embodiments without creative effort, or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A digital variable displacement piston pump unit, comprising a pump body and a piston, wherein the pump body is provided with a plug hole for reciprocating motion of the piston and a pumping channel communicating with the plug hole in the middle, characterized in that, The pumping channel is equipped with a suction valve and a flow control valve at the inlet and outlet, respectively. The flow control valve includes a valve seat and a valve cavity disposed within the valve seat. The valve seat is provided with a valve inlet, a valve outlet, and a pressure relief port communicating with the valve cavity. A valve ball is disposed within the valve cavity, which is pressed against and closes the valve inlet by an elastic element. The flow control valve also includes a top pressure structure that elastically presses against and closes the pressure relief port from the outside. A piezoelectric ceramic element is disposed between the valve seat and the top pressure structure for extending to lift the top pressure structure to open the pressure relief port when the voltage is high.

2. The digital variable piston pump unit according to claim 1, characterized in that, The valve seat has a pressure relief port at one end connected to the valve body. The pressure-relief structure includes a compression spring nested inside and outside the piezoelectric ceramic component, a force transmission component connected between the end of the piezoelectric ceramic component away from the valve seat and the end of the compression spring near the valve seat, and a pressure relief sealing structure pressed by the force transmission component at the pressure relief port.

3. The digital variable piston pump unit according to claim 2, characterized in that, The valve body is a cup-shaped structure with the opening connected to the valve seat and an opening at the bottom. The top pressure structure and the piezoelectric ceramic component are located inside the valve body. The force transmission component is sleeve-shaped and has abutment parts at both ends for abutting the piezoelectric ceramic component and the compression spring, respectively. One of the piezoelectric ceramic component and the compression spring is located inside the force transmission component and the other is located outside the force transmission component.

4. The digital variable piston pump unit according to claim 3, characterized in that, The piezoelectric ceramic component is located inside the force transmission component, and the compression spring is located outside the force transmission component. The force transmission component is a cup-shaped structure with its opening facing the valve seat. The opening of the force transmission component is provided with an outwardly turned flange for abutting against the compression spring. The bottom wall of the force transmission component is used to abut against the piezoelectric ceramic component. The flange and the bottom wall respectively constitute the abutting part. An opening for the working medium to flow is provided on the bottom wall.

5. The digital variable piston pump unit according to any one of claims 2-4, characterized in that, The pressure relief and sealing structure includes a push rod and a sealing ball. One end of the push rod is pressed against or connected to the force transmission component, and the other end of the push rod is provided with a recess for the sealing ball to be inserted. The end of the pressure relief port facing out of the valve cavity is provided with a trumpet-shaped guide structure for guiding the sealing ball to press and seal the pressure relief port.

6. The digital variable displacement piston pump unit according to any one of claims 2-4, characterized in that, The pressure relief and sealing structure includes a push rod, one end of which is pressed against or connected to a force transmission component, and the other end of the push rod is provided with a spherical surface. The end of the pressure relief port facing out of the valve cavity is provided with a trumpet-shaped guiding structure to guide the spherical surface of the push rod to press against and seal the pressure relief port.

7. The digital variable displacement piston pump unit according to any one of claims 1-4, characterized in that, The valve seat includes a seat body and a base mounted on the seat body for receiving the piezoelectric ceramic component. A position adjustment structure is provided between the base and the seat body for adjusting the position of the base along the extension and retraction direction of the piezoelectric ceramic component.

8. The digital variable displacement piston pump unit according to claim 7, characterized in that, A hollow connecting column is provided at the pressure relief port on the main body of the seat. The outer circumferential surface of the connecting column is provided with external threads. The base is a ring structure and its inner circumferential surface is provided with internal threads for threaded connection with the connecting column. The threaded engagement structure between the connecting column and the base constitutes the position adjustment structure.

9. A radial piston pump, comprising a housing, a rotating shaft, and piston pump units arranged around the rotating shaft, wherein the rotating shaft is provided with an eccentric structure for pushing each piston of the piston pump unit, characterized in that, The plunger pump unit is the digital variable plunger pump unit as described in any one of claims 1-8.

10. The radial piston pump according to claim 9, characterized in that, The plunger pump units are arranged in groups, with each plunger pump unit in the group being circumferentially distributed and each plunger pump unit group being axially distributed. At least two groups of plunger pump units are arranged circumferentially staggered to alternately output the working medium.

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