Low pulsation integrated duplex shaft piston pump based on stator bias and damping cooperation

Abstract

The application relates to the technical field of hydraulic power elements, in particular to a low-pulsation integrated double-coupling axial plunger pump based on stator biasing and damping cooperation, which comprises a shared driving shaft, a pump shell and two groups of odd plunger groups with the same number of plungers coaxially connected in series. The two pump assemblies are provided with a specific phase angle in the circumferential phase, and the second pump assembly lags behind the first pump assembly by a quarter of a plunger working period. A rigid confluence flow channel which is connected with the oil discharge ports of the two pumps is integrated in the pump shell to accurately transmit pressure waves. The two valve plates are provided with phase-coordinated damping grooves, wherein the second damping groove is modified in an asymmetric manner to realize accurate staggered oil discharge. The application can utilize the cooperative action of stator reference physical phase shift, rigid flow channel transmission and asymmetric damping groove compensation to eliminate flow pulsation and inhibit confluence impact from the root, significantly reduce fluid excitation noise and improve system running stability.

Description

Technical Field

[0001] This invention relates to the field of hydraulic power components technology, and more specifically, to a low-pulsation integrated dual axial piston pump based on stator bias and damping synergy. Background Technology

[0002] Axial piston pumps are widely used in the hydraulic transmission systems of high-end equipment such as construction machinery, aerospace, and heavy metallurgical equipment due to their advantages such as high power density, high working pressure, and flexible variable control. In complex working conditions such as excavators and loaders that require high-flow-rate, multi-circuit independent or cross-supply, coaxial double axial piston pumps driven in series from the same drive shaft are typically used.

[0003] However, since piston pumps rely on the reciprocating motion of pistons within the cylinder to achieve oil suction and discharge, their output flow and pressure inevitably exhibit periodic pulsations. For the most widely used odd-numbered piston pumps (e.g., 9-piston pumps), the fundamental frequency of the single-pump output flow pulsation is usually high, and the pulsation amplitude is relatively small. However, in a coaxial tandem pump structure, when the discharge lines of the two pumps are externally combined or operate in parallel, if the rotor phases of the two pumps are completely synchronized and the piston motion phase between the parallel pumps is not designed, their pulsation waveforms will undergo "in-phase superposition," resulting in a multiplied amplification of the total flow pulsation amplitude after merging. This can lead to strong fluid vibration noise, pipeline fatigue rupture, and malfunctions of the control valve assembly. Summary of the Invention

[0004] The purpose of this application is to provide a low-pulsation integrated dual axial piston pump based on stator bias and damping synergy, which solves the problems of superimposed pulsation, large fluid excitation noise, oil backflow and cavitation caused by the confluence impact in existing coaxial dual odd-number piston pumps.

[0005] The present invention adopts the following solution:

[0006] A low-pulsation integrated dual axial piston pump based on stator bias and damping coordination, sharing a drive shaft, pump housing, and a first pump assembly and a second pump assembly coaxially connected in series and synchronously driven by the shared drive shaft. The first pump assembly includes a first swashplate support, a first distributor plate, and a first cylinder block and a first piston assembly located between the first swashplate support and the first distributor plate. The second pump assembly includes a second swashplate support, a second distributor plate, and a second cylinder block and a second piston assembly located between the second swashplate support and the second distributor plate. The number of the first piston assembly and the second piston assembly are both an odd number.

[0007] The second pump assembly is offset relative to the first pump assembly by a phase angle α, which satisfies the formula α=π / (2Z), where Z is the number of the first plunger group or the second plunger group. When the common drive shaft synchronously drives the first pump assembly and the second pump assembly to rotate, the highest physical displacement point and the flow distribution switching phase of the second pump assembly are synchronously offset relative to the first pump assembly and lag behind the plunger working cycle of the first pump assembly.

[0008] The pump housing is integrated with a rigid confluence channel, which connects the oil outlets of the first pump assembly and the second pump assembly inside the pump housing, so as to use the internal oil passage to transmit the dynamically superimposed pressure wave to the fluid confluence point with fidelity.

[0009] The high-pressure transition zones of the first distribution plate and the second distribution plate are respectively provided with a first phase cooperative damping groove and a second phase cooperative damping groove. The pre-compression angle of the second phase cooperative damping groove is asymmetrically corrected based on the dynamic superimposed pressure waveform in the rigid confluence channel. It is configured so that the moment when the plunger chamber of the second pump assembly opens to discharge oil avoids the pulsating peak of the oil discharge output of the first pump assembly.

[0010] Furthermore, the first swashplate support and the first distribution plate of the first pump assembly are respectively installed in the pump housing via the first swashplate support positioning pin group and the first distribution plate positioning pin group; and the first swashplate support positioning pin group and the first distribution plate positioning pin group are consistent in circumferential phase to serve as the reference phase for the entire duplex pump; the second distribution plate and the second swashplate support of the second pump assembly are respectively installed in the pump housing via the second distribution plate positioning pin group and the second swashplate support positioning pin group; wherein the projected phases of the second distribution plate positioning pin group and the second swashplate support positioning pin group on the pump housing are all offset from the reference phase by the phase angle α in the circumferential direction.

[0011] Furthermore, the pump housing includes a common intermediate body located between the first pump assembly and the second pump assembly; the first distribution plate and the second distribution plate are respectively fitted and installed on opposite end faces of the common intermediate body.

[0012] Furthermore, the rigid confluence channel is integrally disposed inside the common intermediate body, and the high-pressure oil discharged from the first pump assembly and the second pump assembly converges at an acute angle inside the common intermediate body.

[0013] Furthermore, the rigid confluence channel has a "U" or "V" shaped structure.

[0014] Furthermore, the second phase-coordinated damping groove of the second distribution plate and the first phase-coordinated damping groove of the first distribution plate are asymmetrically arranged in terms of circumferential throttling length or flow cross-sectional area; the pre-compression angle or pressure relief angle of the second phase-coordinated damping groove is compensated by the asymmetrical arrangement to offset the microsecond-level sound velocity time difference when the high-pressure oil is transmitted in the rigid confluence channel, thereby achieving precise destructive interference of the dynamic pressure waveform.

[0015] Furthermore, a front distribution plate anti-misalignment positioning pin is provided on the back of the first distribution plate, and a rear distribution plate anti-misalignment positioning pin is provided on the back of the second distribution plate. The diameter and length of the front distribution plate anti-misalignment positioning pin and the rear distribution plate anti-misalignment positioning pin are incompatible with each other, so as to physically restrict the interchangeability of the first distribution plate and the second distribution plate during the assembly process through the incompatible anti-misalignment structure.

[0016] Furthermore, both the first and second plunger groups consist of nine units, so that the second pump assembly lags behind the first pump assembly by one-quarter of a plunger cycle.

[0017] Beneficial effects:

[0018] 1. This invention deflects the static reference of the swashplate and the distribution plate, avoiding the lateral shear force caused by stator misalignment in the pump body. It can accurately calculate and set a fixed deflection angle corresponding to 1 / 4 cycle of plunger movement for its rated operating pressure and speed, thereby achieving pulsation and noise suppression under the standard operating conditions of the pump, ensuring the high responsiveness and long-term reliability of the metering mechanism.

[0019] 2. This invention integrates a rigid confluence channel within a shared intermediate body, replacing the traditional external high-pressure hose with an extremely short internal oil passage. This eliminates the delay and absorption effect of the hose's "breathing effect" on the propagation of transient pressure waves, ensuring that the 1 / 4-cycle phase difference set by the mechanical structure can be transmitted to the fluid confluence point without loss and with high fidelity, greatly improving the actual noise reduction effect.

[0020] 3. By setting a "phase-coordinated asymmetric damping groove" on the distribution plate that matches the confluence waveform, the sound velocity propagation time difference is actively compensated in the time domain of the micro-flow field. This design allows the plunger chamber of the second pump assembly to cleverly "avoid" the pressure wave peak of the first pump assembly when it is about to discharge oil, effectively suppressing high-pressure oil backflow and cavitation at the moment of confluence, and fundamentally eliminating high-frequency whistling of the fluid.

[0021] 4. This invention achieves extremely low pulsation characteristics simply by modifying the CNC machining program of a standard housing blank, without adding any specific torsional spline shaft or complex, irregularly shaped transmission components. Simultaneously, the asymmetric pin design of the distribution plate completely eliminates the risk of misassembly on the assembly line, making it highly valuable for industrial-scale mass production and offering significant economic benefits. Attached Figure Description

[0022] Figure 1 This is a cross-sectional schematic diagram of a low-pulsation integrated dual axial piston pump based on stator bias and damping coordination according to an embodiment of the present invention.

[0023] Figure 2 This is a schematic diagram of the installation structure of the first pump assembly of a low-pulsation integrated dual axial piston pump based on stator bias and damping coordination according to an embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of the installation structure of the second pump assembly of a low-pulse integrated dual axial piston pump based on stator bias and damping coordination according to an embodiment of the present invention.

[0025] Figure 4 This is a schematic diagram of the back structure of the first distribution plate of a low-pulsation integrated dual axial piston pump based on stator bias and damping coordination according to an embodiment of the present invention.

[0026] Figure 5 This is a schematic diagram of the back structure of the second distribution plate of a low-pulsation integrated dual axial piston pump based on stator bias and damping coordination according to an embodiment of the present invention.

[0027] Figure 6 This is a schematic diagram of the destructive interference waveform of flow pulsation according to an embodiment of the present invention;

[0028] Figure label:

[0029] Common drive shaft 1, pump housing 2, first cylinder block 3, first plunger assembly 4, first swashplate support 5, first distributor plate 6, second cylinder block 7, second plunger assembly 8, second swashplate support 9, second distributor plate 10, common intermediate body 13, first phase co-damping groove 14, second distributor plate positioning pin assembly 15, rear distributor plate anti-misalignment positioning pin 16, second phase co-damping groove 17, second swashplate support positioning pin assembly 18, front distributor plate anti-misalignment positioning pin 19, first pump assembly 21, second pump assembly 22, first swashplate support positioning pin assembly 24, first distributor plate positioning pin assembly 25, first drain port 31, second drain port 32, rigid confluence channel 33, total drain outlet 34. Detailed Implementation

[0030] This embodiment provides a low-pulsation integrated dual axial piston pump based on stator bias and damping synergy, the overall structure of which is as follows: Figure 1As shown, it mainly consists of a common drive shaft 1, a pump housing 2, a first pump assembly 21, a second pump assembly 22, and a common intermediate body 13 located between the two pump assemblies. The common drive shaft 1 runs through the front and rear bearing supports of the entire pump housing 2. The first pump assembly 21 serves as the front pump, and the second pump assembly 22 serves as the rear pump, and the two are arranged coaxially in series. In terms of power transmission, the common drive shaft 1 is connected to the first cylinder 3 of the first pump assembly 21 and the second cylinder 7 of the second pump assembly 22 through a spline structure on its outer circumference. When an external power source drives the common drive shaft 1 to rotate, the first cylinder 3 and the second cylinder 7 rotate synchronously.

[0031] The internal structure of the first pump assembly 21 includes a first swashplate support 5, a first cylinder 3, a first plunger assembly 4, and a first distribution plate 6. Multiple plungers in the first plunger assembly 4 are evenly distributed within the plunger chambers of the first cylinder 3. The first swashplate support 5 provides an inclined plane, and the slippers of the first plunger assembly adhere to the sliding surface of the first swashplate support 5 under the action of spring preload and hydraulic pressure. The first distribution plate 6 is fitted onto the front end face of the common intermediate body 13, and the flow distribution control within the plunger chambers of the first cylinder 3 is achieved through the oil suction and discharge windows on the first distribution plate 6.

[0032] The second pump assembly 22 has a structure basically the same as the first pump assembly 21, including a second swashplate support 9, a second cylinder block 7, a second plunger assembly 8, and a second distributor plate 10. The second distributor plate 10 is fitted onto the rear end face of the common intermediate body 13. In this embodiment, the number of plungers Z in both the first plunger assembly 4 and the second plunger assembly 8 is selected as 9. This odd-numbered plunger design has good flow smoothness under single-pump operation, but requires specific phase interference design when the two pumps merge.

[0033] Combined with appendix Figure 2 and attached Figure 3 In the first pump assembly 21, the first swashplate support 5 is installed inside the front housing of the pump housing 2 via the first swashplate support locating pin group 24, and the first distribution plate 6 is fixed to the end face of the common intermediate body 13 via the first distribution plate locating pin group 25. The first distribution plate locating pin group 25 and the first swashplate support locating pin group 24 are aligned in the circumferential phase, serving as the reference phase for the entire duplex pump. The first distribution plate 6 and the first swashplate support 5 are provided with a first locating pin hole group that mates with the first distribution plate locating pin group 25 and the first swashplate support locating pin group 24.

[0034] For the second pump assembly 22, the second distribution plate locating pin group 15 and the second swashplate support locating pin group 18 are used to install the second distribution plate 10 and the second swashplate support 9, respectively. It should be noted that the second distribution plate locating pin group 15 and the second swashplate support locating pin group 18 are respectively installed within the second locating pin hole group. To achieve precise waveform destructive interference, its stator components are forcibly deflected in their physical installation position. The projected phase of the second distribution plate locating pin group 15, used to fix the second distribution plate 10, on the pump housing 2, and the second swashplate support locating pin group 18, used to fix the second swashplate support 9, are both offset by a phase angle α in the circumferential direction relative to the reference phase; the phase angle α satisfies the formula α=π / (2Z); for example, when the number of plungers Z equals 9, this phase angle is 10°. Due to this physical offset, when the shared drive shaft 1 drives the two cylinders to rotate synchronously, the plunger of the second pump assembly 22 lags behind the plunger of the first pump assembly 21 by 10° in rotation angle when reaching the top dead center of its stroke. Since the rotation angle corresponding to a complete working cycle of the plunger pump is 40°, the 10° deviation corresponds exactly to 1 / 4 of a plunger working cycle.

[0035] Combination Figure 1 As shown, in the fluid transmission path design, a rigid confluence channel 33 is integrated inside the pump housing 2. This rigid confluence channel 33 is located within the metal matrix of the common intermediate body 13. The high-pressure oil discharged from the first pump assembly 21 enters the common intermediate body 13 through the first drain port 31, and the high-pressure oil discharged from the second pump assembly 22 enters the common intermediate body 13 through the second drain port 32. The rigid confluence channel 33 has a U-shaped or V-shaped structure in geometry, so that the two high-pressure fluids merge at an acute angle inside the common intermediate body 13, for example, designed to be 30°~80°, and finally output to the external load through the total drain port 34. This integrated rigid channel design eliminates the expansion deformation caused by pressure pulsation impact of traditional high-pressure hoses through all-metal piping, ensuring that the 10° phase difference set by the mechanical structure does not cause phase drift during the transmission of fluid pressure waves, thus guaranteeing the physical basis of waveform cancellation.

[0036] Combination Figure 4 and Figure 5As shown, to address the dynamic back pressure impact that may occur during the confluence of two pumps, this invention implements an asymmetric damping cooperative design on the distribution pair. The high-pressure transition zone of the first distribution plate 6 is equipped with a standard first-phase cooperative damping groove 14. The high-pressure transition zone of the second distribution plate 10 is equipped with a modified second-phase cooperative damping groove 17. The second-phase cooperative damping groove 17 has been finely compensated in terms of circumferential throttling length and opening start angle. For example, the throttling length of the second-phase cooperative damping groove 17 is increased by 5% compared to the first-phase cooperative damping groove 14, and the pre-compression angle is reduced by 3°. This allows the transient pressure released by the plunger cavity of the second pump assembly 22 at the moment of opening for oil discharge to precisely avoid the pulsating peak of the oil discharge output of the first pump assembly 21, suppressing high-pressure oil backflow and cavitation noise. In other words, this asymmetric correction compensates for the slight delay caused by the limited sound velocity during oil transmission in the rigid confluence channel 33 by adjusting the microsecond-level timing of the opening of the plunger cavity of the second pump assembly 22 for oil discharge.

[0037] In terms of assembly error prevention, this embodiment achieves unique locking of the assembly position through the incompatibility of geometric dimensions. In this embodiment, the front distribution plate error prevention positioning pin 19 on the back of the first distribution plate 6 and the rear distribution plate error prevention positioning pin 16 on the back of the second distribution plate 10 adopt an incompatible design; for example, the pin diameters and pin hole depths are different. This structure physically restricts the interchangeability of the two during the assembly process, avoiding assembly errors on the production line.

[0038] Combination Figures 1 to 6 As shown, the logical and physical processes in actual operation of this embodiment are as follows:

[0039] An external power source drives the first cylinder block 3 and the second cylinder block 7 to rotate at the same angular velocity via a shared drive shaft 1. During rotation, the first plunger assembly 4 and the second plunger assembly 8 reciprocate within their respective cylinder bores. Due to a 10° physical deviation in the circumferential phase between the first swashplate support 5 and the second swashplate support 9, the flow pulsation curve A generated by the first plunger assembly 4 and the flow pulsation curve B generated by the second plunger assembly 8 are offset by 90° (i.e., 1 / 4 cycle) in phase.

[0040] The high-pressure oil discharged from the first pump assembly 21 enters the rigid confluence channel 33 through the first drain port 31, while the high-pressure oil discharged from the second pump assembly 22 enters the same channel through the second drain port 32. Due to the high rigidity of the rigid confluence channel 33, the two pressure waves with a phase difference are transmitted faithfully within the channel. At this time, the peak of curve A and the trough of curve B coincide on the time axis.

[0041] At the instant the two fluids merge, the second phase-coordinated damping groove 17 actively adapts to the dynamic back pressure at the merging point by slowing down the pressurization rate of the plunger cavity of the second pump assembly 22. This process, through the gradual design of the throttling area, controls the pressure jump amplitude when the second pump assembly 22 starts discharging oil to a low level, preventing the backflow of high-pressure oil at the merging point into the second pump assembly 22.

[0042] The combined oil flows superimpose at the main discharge outlet (point 34) to form the total flow rate. Through the principle of waveform destructive interference, the pulsating components of curves A and B cancel each other out, ultimately forming the total flow rate waveform shown in curve C. Compared to curve D, which is obtained solely by superimposing curves A without phase shifting, the pulsation rate of the total flow rate is significantly reduced, fundamentally solving the high-frequency excitation problem of coaxial dual odd-numbered piston pumps.

[0043] During the manufacturing process, the phase difference between the two sets of pin holes is pre-set during the blank machining stage of the pump housing 2, achieving zero-cost phase compensation. This design approach, which replaces hardware additions with manufacturing process optimization, gives the invention a strong cost competitive advantage while maintaining excellent performance. During assembly line production, the physical error-proofing structure based on the pin diameter eliminates the impact of human factors on product performance.

[0044] Finally, through the appendix Figure 6 The experimental data curves show that, after adopting the technical solution of this invention, the pressure fluctuation amplitude at the total oil outlet (point 34) is significantly reduced compared to the traditional in-phase dual pump. This results in a substantial decrease in the vibration acceleration of the downstream hydraulic pipeline, which is beneficial for extending the service life of hydraulic accessories and significantly improving the operator's driving comfort. The low pulsation characteristics provided by this invention also make this pump a promising candidate for application in fields such as aerospace and precision machine tools where extreme requirements for hydraulic stability exist.

[0045] It should be understood that the above are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions that fall within the scope of the present invention are within the scope of protection of the present invention.

[0046] The accompanying drawings used in the above description of the embodiments only illustrate certain embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

Claims

1. A low-pulsation integrated dual axial piston pump based on stator bias and damping coordination, comprising a common drive shaft, a pump housing, and a first pump assembly and a second pump assembly coaxially connected in series and synchronously driven by the common drive shaft. The first pump assembly includes a first swashplate support, a first distribution plate, and a first cylinder block and a first piston assembly located between the first swashplate support and the first distribution plate. The second pump assembly includes a second swashplate support, a second distribution plate, and a second cylinder block and a second piston assembly located between the second swashplate support and the second distribution plate. The first piston assembly and the second piston assembly both have the same odd number. The second pump assembly is offset relative to the first pump assembly by a phase angle α, which satisfies the formula α=π / (2Z), where Z is the number of the first plunger group or the second plunger group. When the common drive shaft synchronously drives the first pump assembly and the second pump assembly to rotate, the highest physical displacement point and the flow distribution switching phase of the second pump assembly are synchronously offset relative to the first pump assembly and lag behind the plunger working cycle of the first pump assembly. The pump housing is integrated with a rigid confluence channel, which connects the oil outlets of the first pump assembly and the second pump assembly inside the pump housing, so as to use the internal oil passage to transmit the dynamically superimposed pressure wave to the fluid confluence point with fidelity. The high-pressure transition zones of the first distribution plate and the second distribution plate are respectively provided with a first phase cooperative damping groove and a second phase cooperative damping groove. The pre-compression angle of the second phase cooperative damping groove is asymmetrically corrected based on the dynamic superimposed pressure waveform in the rigid confluence channel. It is configured so that the moment when the plunger chamber of the second pump assembly opens to discharge oil avoids the pulsating peak of the oil discharge output of the first pump assembly.

2. The low-pulsation integrated dual axial piston pump based on stator bias and damping synergy as described in claim 1, characterized in that, The first swashplate support and the first distribution plate of the first pump assembly are respectively installed in the pump housing by the first swashplate support positioning pin group and the first distribution plate positioning pin group; and the first swashplate support positioning pin group and the first distribution plate positioning pin group are consistent in circumferential phase to serve as the reference phase of the entire double pump. The second distribution plate and the second swashplate support of the second pump assembly are respectively installed in the pump housing via the second distribution plate positioning pin group and the second swashplate support positioning pin group; wherein the projection phase of the second distribution plate positioning pin group and the second swashplate support positioning pin group on the pump housing are both offset from the reference phase in the circumferential direction by the phase angle α.

3. The low-pulsation integrated dual axial piston pump based on stator bias and damping synergy as described in claim 1, characterized in that, The pump housing includes a common intermediate body located between the first pump assembly and the second pump assembly; the first distribution plate and the second distribution plate are respectively attached to the opposite end faces of the common intermediate body.

4. The low-pulsation integrated dual axial piston pump based on stator bias and damping synergy as described in claim 3, characterized in that, The rigid confluence channel is integrally disposed inside the common intermediate body, and the high-pressure oil discharged from the first pump assembly and the second pump assembly converges at an acute angle inside the common intermediate body.

5. The low-pulsation integrated dual axial piston pump based on stator bias and damping synergy as described in claim 4, characterized in that, The rigid confluence channel has a "U" or "V" shaped structure.

6. The low-pulsation integrated dual axial piston pump based on stator bias and damping synergy as described in claim 1, characterized in that, The second phase co-damping groove of the second distribution plate and the first phase co-damping groove of the first distribution plate are asymmetrically arranged in terms of circumferential throttling length or flow cross-sectional area; the pre-compression angle or pressure relief angle of the second phase co-damping groove is compensated by the asymmetrical arrangement to offset the microsecond-level sound velocity time difference when the high-pressure oil is transmitted in the rigid confluence channel, thereby achieving precise destructive interference of the dynamic pressure waveform.

7. The low-pulsation integrated dual axial piston pump based on stator bias and damping synergy as described in claim 1, characterized in that, The back of the first distribution plate is provided with a front distribution plate anti-misalignment positioning pin, and the back of the second distribution plate is provided with a rear distribution plate anti-misalignment positioning pin. The diameter and length of the front distribution plate anti-misalignment positioning pin and the rear distribution plate anti-misalignment positioning pin are incompatible with each other, so as to physically restrict the interchangeability of the first distribution plate and the second distribution plate during the assembly process through the incompatible anti-misalignment structure.

8. The low-pulsation integrated dual axial piston pump based on stator bias and damping synergy as described in claim 1, characterized in that, The first plunger group and the second plunger group each have 9 units, so that the second pump assembly lags behind the first pump assembly by 1 / 4 of a plunger working cycle.

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