Plunger pump variable displacement device capable of quickly responding to reduce pressure overshoot and control method

Abstract

The invention relates to a plunger pump variable device capable of quickly responding and reducing pressure overshoot and a control method, the plunger pump variable device comprises a hydraulic amplification variable device connected with a swash plate, the hydraulic amplification variable device is connected with a giant magnetostrictive driver, and the plunger pump variable device further comprises a controller; the input end of the controller is connected with a temperature sensor, a pump oil outlet pressure sensor and a load pressure port pressure sensor, the temperature sensor is arranged on the giant magnetostrictive driver, and the output end of the controller is connected with the giant magnetostrictive driver. According to the plunger pump variable device capable of quickly responding and reducing the pressure overshoot and the control method, the output displacement of the giant magnetostrictive actuator is accurately controlled by controlling the input current of the giant magnetostrictive actuator, and then the displacement of the swash plate can be accurately controlled by hydraulically amplifying the appropriate area ratio of a large piston and a small piston of the variable device; the response speed of the plunger pump is effectively increased, the pressure overshoot generated when the load pressure of the executing mechanism changes suddenly is reduced, and the response rapidity and the pressure stability of the plunger pump are further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of construction machinery, and specifically to a piston pump variable device and a control method with fast response and reduced pressure overshoot. Background Art

[0002] The piston pump is a key control device in the hydraulic system. Its performance plays a crucial role in the performance of the entire pump control system. The piston pump has the advantages of high rated pressure, compact structure, high efficiency, and convenient flow regulation, and is widely used in occasions where high pressure, large flow, and flow regulation are required, such as hydraulic presses, construction machinery, and ships.

[0003] As one of the key structures of the swashplate axial piston pump, the swashplate variable mechanism changes the inclination angle of the swashplate by the left and right movement of the variable piston, and then changes the volume of the closed cavity composed of the cylinder block and the piston assembly, so as to realize the change of the displacement of the piston pump. Most traditional piston pump variable mechanisms use control oil to act on the variable mechanism through a control valve, resulting in a complex structure, high requirements for the machining accuracy of parts, and inability to avoid the instantaneous high pressure and high torque generated during load mutation, which has a certain impact on the performance and safety of the hydraulic system.

[0004] The existing way for the piston pump to achieve variable is generally that the control oil acts on the variable piston to drive the swing angle of the swashplate, and then the piston pump variable is realized. However, when the load suddenly changes (such as the bucket of an excavator suddenly touches the ground), during this process, due to the instantaneous increase in the pump outlet pressure, the pump outlet pressure may exceed the rated pressure of the pump, and because of the certain hysteresis of the spool movement in the variable mechanism, the variable piston that drives the change of the swashplate angle of the pump cannot respond in time, and then the variable piston fails to generate displacement in time to push the swashplate to rotate and make the pump variable. If the pump is in the large displacement state at this time, combined with the pressure overshoot, it will cause the product of pressure and displacement, that is, the instantaneous torque of the pump, to be very high, resulting in certain potential safety hazards. Therefore, how to improve the response speed of the piston pump, reduce the pressure overshoot and instantaneous high torque generated by load mutation is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the above-mentioned prior art, and provide a piston pump variable device and a control method with fast response and reduced pressure overshoot, which have a simple structure and good effects.

[0006] The present invention is realized by the following technical solutions: A piston pump variable device with fast response and reduced pressure overshoot includes a hydraulic amplification variable device connected to the swashplate, and the hydraulic amplification variable device is connected with a giant magnetostrictive actuator;

[0007] Giant magnetostrictive actuator, comprising a sleeve, with a rear cover and a cover plate respectively provided at two ends of the sleeve. An output rod is provided inside the sleeve. One end of the output rod passes through the cover plate and is connected to a hydraulic amplification variable device. Between the other end of the output rod and the rear cover, there are a permanent magnet and a magnetostrictive rod, and a drive coil is provided on the outer periphery of the permanent magnet and the magnetostrictive rod; a disc spring is provided on the outer periphery of the output rod near the cover plate.

[0008] Hydraulic amplification variable device, comprising a piston chamber, with a large-end piston provided at one end of the piston chamber. The large-end piston is connected to the output rod. A small-end piston is provided at the other end of the piston chamber. The small-end piston is connected to an inclined plate through a variable rod.

[0009] It further includes a controller. The input end of the controller is connected to a temperature sensor, a pump outlet pressure sensor, and a load pressure port pressure sensor. The temperature sensor is arranged on the giant magnetostrictive actuator. The output end of the controller is connected to the giant magnetostrictive actuator. Further, partitions are provided in the middle of both the sleeve and the output rod. The sleeve is of an H-shaped structure, and the output rod is of a cross-shaped structure. The partition of the output rod is located on the side of the sleeve partition close to the cover plate.

[0010] A permanent magnet, a magnetostrictive rod, and a drive coil are arranged between the sleeve partition and the rear cover, and a disc spring is arranged between the sleeve partition and the cover plate.

[0011] Seal I and seal II are respectively provided between the large-end piston and the small-end piston and the piston chamber.

[0012] The end face ratio of the large-end piston and the small-end piston is a determined value.

[0013] The temperature sensor is a patch type temperature sensor, and the temperature sensor is arranged on the outer side of the sleeve.

[0014] A control method for variable control of a plunger pump with fast response and reduced pressure overshoot. By using the pump outlet pressure sensor and the load pressure port pressure sensor to collect signals in real time, the pressure difference error е and the pressure difference error rate Δе are calculated as input signals. Through PID operation, the output signal u is obtained to adjust the input current. Then, based on the calibrated current-displacement characteristic curve of the giant magnetostrictive actuator, the displacement relationship is obtained, and finally, the inclined plate angle is adjusted.

[0015] In the calculation method of the pressure difference error е and the pressure difference error rate Δе, the pressure difference error е = ΔP SET -ΔP, pressure difference error rate where, ΔP SET is the set pressure difference of the load sensing system, and the target pressure difference is set as ΔP SET = 2 MPa, the actual pressure difference ΔP = P P -PSET , P P is the pump output pressure, P SET为 Load feedback pressure.

[0016] The PID operation consists of three parts:

[0017]

[0018] Among them, e(t) is the error e at the current moment;

[0019] K P is the proportional coefficient, used to adjust the weight of the current error;

[0020] Ki is the integral coefficient, used to adjust the weight of the historical error accumulation;

[0021] Kd is the differential coefficient, used to adjust the weight of the error change trend.

[0022] Use a temperature sensor to collect the real-time temperature of the giant magnetostrictive actuator as the input signal, and superimpose the temperature drift compensation amount on the PID calculation result Suppress the influence of the thermal expansion of the magnetostrictive material. Among them, T is the real-time collected temperature, T0 is the normal temperature (usually set to 25 °C), and α = 0.5um / °C, β = 0.1um·s / °C are the characteristic coefficients of the giant magnetostrictive material.

[0023] The present invention has the following advantages: A variable device and control method for a plunger pump with fast response and reduced pressure overshoot of the present invention can accurately control the output displacement by controlling the input current of the giant magnetostrictive actuator, and then accurately control the swashplate displacement amount through the appropriate area ratio of the large and small pistons of the hydraulic amplification variable device, effectively improving the response speed of the plunger pump and reducing the pressure overshoot generated when the load pressure of the actuator suddenly changes, further improving the response rapidity and pressure stability of the plunger pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings, as a part of the present invention, are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention, but do not constitute an improper limitation to the present invention. Obviously, the drawings in the following description are only some embodiments, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts.

[0025] In the drawings:

[0026] Figure 1 is the structural schematic diagram of the present invention;

[0027] Figure 2 is the schematic diagram of the variable control method of the present invention;

[0028] Figure 3 is the magnetostrictive characteristic curve of the present invention.

[0029] In the figure: 1. Giant magnetostrictive actuator, 11. Sleeve, 12. Rear cover, 13. Drive coil, 14. Permanent magnet, 15. Magnetostrictive rod, 16. Output rod, 17. Disc spring, 18. Cover plate, 19. Temperature sensor, 2. Hydraulic amplification variable device, 21. Piston chamber, 22. Large-end piston, 23. Seal I, 24. Small-end piston, 25. Seal II, 26. Swash plate, 27. Variable rod.

[0030] It should be noted that these drawings and textual descriptions are not intended to limit the scope of the concept of the present invention in any way, but to illustrate the concept of the present invention to those skilled in the art by reference to specific embodiments. Detailed implementation manners

[0031] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0032] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0033] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] Such as Figures 1 to 2The described plunger pump variable device for quickly responding and reducing pressure overshoot includes a hydraulic amplification variable device 2 connected to a swash plate 26, and a giant magnetostrictive actuator 1 is connected to the hydraulic amplification variable device 2; it also includes a controller. The input end of the controller is connected to a temperature sensor 19, a pump outlet pressure sensor, and a load pressure port pressure sensor. The temperature sensor 19 is arranged on the giant magnetostrictive actuator 1, and the output end of the controller is connected to the giant magnetostrictive actuator 1. In the plunger pump variable device for quickly responding and reducing pressure overshoot of the present invention, the output end of the giant magnetostrictive actuator is connected to the amplification piston of the amplification variable device through a rigid connecting rod, and the ball head at the output end of the amplification piston directly acts on the swash plate. The output displacement of the giant magnetostrictive actuator causes the variable piston to displace through hydraulic amplification, and then drives the swash plate to rotate. Since the external dimension of the magnetic body of the giant magnetostrictive actuator changes when the magnetic field changes, the size of the magnetic body is controlled by changing the current of the giant magnetostrictive actuator, and then the left and right movement of the variable piston is controlled to change the volume of the closed cavity composed of the cylinder block and the plunger assembly, thereby changing the inclination angle of the swash plate, and thus realizing the change of the displacement of the plunger pump. At the same time, a temperature sensor is externally connected to the giant magnetostrictive actuator, and pressure sensors are connected to the pump outlet and the load pressure port. The sensors are connected to the controller. By using the current characteristics of the giant magnetostrictive actuator and combining the data collected by the temperature sensor and the pressure sensor, the size of the input current can be accurately controlled by using the adaptive PID algorithm to control the displacement of the output rod, and then the displacement of the swash plate can be accurately controlled through an appropriate area ratio (such as 1:20) of the hydraulic amplification piston. The variable device of the present invention utilizes the characteristic of magnetostrictive direct drive with a response time ≤ 2 ms to play a role in suppressing pressure overshoot in the case of sudden load changes, avoiding the hysteresis caused by the movement of the spool valve, and can effectively improve the response speed of the plunger pump and reduce the pressure overshoot generated when the load pressure of the actuator suddenly changes, further enhancing the response rapidity and pressure stability of the plunger pump. Such as Figure 1A plunger pump variable device for quickly responding to reduce pressure overshoot. The giant magnetostrictive actuator 1 includes a sleeve 11. Both ends of the sleeve 11 are respectively provided with a rear cover 12 and a cover plate 18. An output rod 16 is arranged inside the sleeve 11. One end of the output rod 16 passes through the cover plate 18 and is connected to the hydraulic amplification variable device 2. Between the other end of the output rod 16 and the rear cover 12, there are a permanent magnet 14 and a magnetostrictive rod 15. A drive coil 13 is arranged on the outer periphery of the permanent magnet 14 and the magnetostrictive rod 15. A disc spring 17 is arranged on the outer periphery of the output rod 16 near the cover plate 18. The giant magnetostrictive actuator of the present invention includes a rear cover, a permanent magnet, a magnetostrictive rod, a drive coil, a sleeve, an output rod, a disc spring and a cover plate. The rear cover and the cover plate are respectively arranged at both ends of the sleeve. Inside the sleeve, from the rear cover to the cover plate, a permanent magnet, a magnetostrictive rod and an output rod are sequentially arranged. The drive coil is arranged on the outer periphery of the permanent magnet and the magnetostrictive rod. The disc spring is arranged on the outer periphery of the output rod. Among them, the number of permanent magnets is three, the number of magnetostrictive rods is two, the permanent magnets and the magnetostrictive rods are arranged at intervals, one end of the output rod is connected to the permanent magnet, and the other end passes through the cover plate and is connected to the hydraulic amplification variable device.

[0035] As Figure 1 For the plunger pump variable device for quickly responding to reduce pressure overshoot described above, partitions are provided in the middle of both the sleeve 11 and the output rod 16. The sleeve 11 is of an H-shaped structure, and the output rod 16 is of a cross-shaped structure. The partition of the output rod 16 is located on the side of the partition of the sleeve 11 close to the cover plate 18. Between the partition of the sleeve 11 and the rear cover 12, a permanent magnet 14, a magnetostrictive rod 15 and a drive coil 13 are arranged. Between the partition of the sleeve 11 and the cover plate 18, a disc spring 17 is arranged. In the present invention, the inside of the sleeve is divided into two parts, the left part close to the rear cover is provided with a permanent magnet, a magnetostrictive rod and a drive coil, the right part close to the cover plate is provided with an output rod and a disc spring, a partition is also provided in the middle of the output rod, the partition of the output rod is arranged in the right space of the sleeve, one end of the output rod passes through the sleeve partition and is connected to the permanent magnet, and the other end passes through the cover plate and is connected to the hydraulic amplification variable device to move rightward. During use, the output rod can be reset under the action of the disc spring, and the maximum leftward movement position of the output rod is limited by the sleeve partition. As Figure 1 For the plunger pump variable device for quickly responding to reduce pressure overshoot described above, the temperature sensor 19 is a patch type temperature sensor, and the temperature sensor 19 is arranged on the outer side of the sleeve 11. The temperature sensor of the present invention is of the patch type and is fixed outside the sleeve, and is used to detect the real-time temperature of the giant magnetostrictive actuator and transmit it to the controller as an input value of the input current algorithm.

[0036] As Figure 1A plunger pump variable device for rapid response and pressure overshoot reduction, a hydraulic amplification variable device 2, includes a piston chamber 21. One end of the piston chamber 21 is provided with a large-end piston 22, which is connected to the output rod 16. The other end of the piston chamber 21 is provided with a small-end piston 24, which is connected to the swash plate 26 through a variable rod 27. Seals I 23 and II 25 are respectively provided between the large-end piston 22 and the small-end piston 24 and the piston chamber 21. The end face ratio of the large-end piston 22 and the small-end piston 24 is a determined value. The hydraulic amplification variable device of the present invention includes a piston chamber. The left and right ends of the piston chamber are respectively a large chamber and a small chamber, which are interconnected. A large-end piston is provided in the large chamber and is connected to the output rod of the giant magnetostrictive actuator. A small-end piston is provided in the small chamber and is connected to the swash plate through a variable rod. The area ratio of the large-end piston and the small-end piston can be selected according to needs to meet the working requirements. In addition, seals are provided between the large-end piston and the small-end piston and the piston chamber to ensure the stability of the equipment operation, prevent liquid leakage from causing errors in the amplification ratio, and improve the accuracy of the hydraulic amplification variable device.

[0037] A control method for a plunger pump variable with rapid response and pressure overshoot reduction. By using a pump outlet pressure sensor and a load pressure port pressure sensor to collect signals in real time, the pressure difference error е and the pressure difference error rate Δе are calculated as input signals. Through PID operation, the output signal u is obtained to adjust the input current. Then, according to the calibrated current-displacement characteristic curve of the giant magnetostrictive actuator 1, the displacement relationship is obtained, as Figure 3 shown, the displacement of the output rod can be accurately controlled, and finally the swash plate angle is adjusted.

[0038] In the calculation method of the pressure difference error е and the pressure difference error rate Δе, the pressure difference error е = ΔP SET -ΔP, the pressure difference error rate where, ΔP SET is the set pressure difference of the load sensing system, the target pressure difference is set as ΔP SET = 2 MPa, the actual pressure difference ΔP = P P - P SET , P P is the pump output pressure, P SET为 is the load feedback pressure.

[0039] The PID operation consists of three parts:

[0040]

[0041] where, e(t) is the error e at the current moment;

[0042] K P is the proportional coefficient, which is used to adjust the weight of the current error;

[0043] Ki is the integral coefficient, which is used to adjust the weight of the historical error accumulation;

[0044] Kd is the differential coefficient, which is used to adjust the weight of the error change trend.

[0045] At the same time, the temperature sensor 19 is used to collect the real-time temperature of the giant magnetostrictive actuator 1 as the input signal, and the temperature drift compensation amount is superimposed on the PID calculation result To suppress the influence of the thermal expansion of magnetostrictive materials (such as Terfenol-D), the accuracy and stability of the variable mechanism can be further improved. Among them, T is the real-time collected temperature, T0 is the normal temperature (usually set to 25 °C), α = 0.5um / °C, and β = 0.1um·s / °C are the characteristic coefficients of the giant magnetostrictive material. The plunger pump variable device and control method for rapid response and reduced pressure overshoot of the present invention directly outputs a linear displacement by the giant magnetostrictive actuator, and then amplifies the micron-level magnetostrictive displacement to a millimeter-level variable piston displacement through a hydraulic amplification variable mechanism and drives the swash plate angle. By combining the adaptive PID control method to control the swash plate variable through the giant magnetostrictive actuator, the flow control of the plunger pump can be accurately realized, and the output displacement deviation of the magnetostrictive material caused by temperature rise is corrected in real time by using an integrated temperature sensor and a temperature compensation algorithm, avoiding the feedback variable mechanism composed of valve groups and oil circuits in traditional plunger pumps, eliminating the delay caused by the movement of the spool, and improving the response speed of the plunger pump.

[0046] In the specification provided here, a large number of specific details are described. However, it can be understood that the embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures, and technologies are not shown in detail so as not to obscure the understanding of this specification.

[0047] In addition, those skilled in the art can understand that although some embodiments described herein include certain features contained in other embodiments rather than other features, the combination of the features of different embodiments also means that it is within the protection scope of the present invention and forms different embodiments. For example, in the above embodiments, those skilled in the art can use them in combination according to the known technical solutions and the technical problems to be solved by this application. The above description is only a preferred embodiment of the present invention, and does not impose any form of limitation on the present invention. Although the present invention has been disclosed above with a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art of this patent can make some changes or modifications to the above-mentioned technical content as equivalent changes within the scope of the technical solution of the present invention, but as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change, and modification made to the above embodiments according to the technical essence of the present invention still fall within the scope of the present invention.

Claims

1. A plunger pump variable displacement device with fast response and reduced pressure overshoot, characterized in that: A hydraulic variable amplification device (2) connected to the swash plate (26), wherein the hydraulic variable amplification device (2) is connected to a giant magnetostrictive actuator (1); A giant magnetostrictive actuator (1) comprises a sleeve (11), wherein two ends of the sleeve (11) are respectively provided with a rear cover (12) and a cover plate (18), an output rod (16) is provided inside the sleeve (11), one end of the output rod (16) passes through the cover plate (18) and is connected to a hydraulic variable amplification device (2), a permanent magnet (14) and a magnetostrictive rod (15) are provided between the other end of the output rod (16) and the rear cover (12), a driving coil (13) is provided on the periphery of the permanent magnet (14) and the magnetostrictive rod (15); and a disc spring (17) is provided on the periphery of one end of the output rod (16) close to the cover plate (18); A hydraulic variable amplification device (2) comprises a piston chamber (21), one end of the piston chamber (21) is provided with a large end piston (22), the large end piston (22) is connected to an output rod (16), and the other end of the piston chamber (21) is provided with a small end piston (24), the small end piston (24) is connected to a swash plate (26) via a variable rod (27); It also includes a controller, the input end of the controller is connected to a temperature sensor (19), a pump oil outlet pressure sensor and a load pressure port pressure sensor, the temperature sensor (19) is arranged on the giant magnetostrictive actuator (1), and the output end of the controller is connected to the giant magnetostrictive actuator (1).

2. A plunger pump variable displacement device with fast response and reduced pressure overshoot as claimed in claim 1, characterized in that: A spacer is provided between the sleeve (11) and the output rod (16); the sleeve (11) is an H-shaped structure, the output rod (16) is a cross-shaped structure, and the spacer of the output rod (16) is located on a side of the sleeve (11) spacer close to the cover plate (18).

3. A plunger pump variable displacement device with fast response and reduced pressure overshoot as claimed in claim 2, characterized in that: A permanent magnet (14), a magnetostrictive rod (15) and a driving coil (13) are arranged between the partition of the sleeve (11) and the rear cover (12), and a disc spring (17) is arranged between the partition of the sleeve (11) and the cover plate (18).

4. A plunger pump variable displacement device with fast response and reduced pressure overshoot as claimed in claim 1, characterized in that: A sealing member I (23) and a sealing member II (25) are respectively provided between the large end piston (22) and the small end piston (24) and the piston chamber (21).

5. A plunger pump variable displacement device with fast response and reduced pressure overshoot as claimed in claim 1, characterized in that: The end surface ratio of the large end piston (22) and the small end piston (24) is a certain value.

6. A plunger pump variable displacement device with fast response and reduced pressure overshoot as claimed in claim 1, characterized in that: The temperature sensor (19) is a patch-type temperature sensor, and the temperature sensor (19) is arranged on the outside of the sleeve (11).

7. A method for controlling the variable of a piston pump variable device to reduce pressure overshoot in a quick response, characterized in that: The pressure difference error е and the pressure difference error rate Δе are calculated by real-time signal acquisition through the pump oil outlet pressure sensor and the load pressure port pressure sensor as input signals, and the output signal u is obtained through PID operation to adjust the input current, and then the displacement relationship is obtained through the calibrable current-displacement characteristic curve of the giant magnetostrictive actuator (1), and finally the swash plate angle is adjusted.

8. A variable displacement control method for a plunger pump with fast response and reduced pressure overshoot as claimed in claim 7, characterized in that: In the calculation method of the pressure difference error е and the pressure difference error rate Δе, the pressure difference error е=ΔP SET -ΔP, differential pressure error rate Among them, ΔP SET Set the pressure difference for the load sensing system. The target pressure difference is set to ΔP SET =2MPa, actual pressure difference ΔP=P P -P SET ,P P is the pump output pressure, P SET为 Load feedback pressure.

9. A variable control method for a plunger pump with fast response and reduced pressure overshoot as claimed in claim 7, characterized in that: The PID operation consists of three parts: Among them, e(t) is the error e at the current moment; K P is the proportional coefficient, which is used to adjust the weight of the current error; Ki is the integral coefficient, which is used to adjust the weight of historical error accumulation; Kd is the differential coefficient, which is used to adjust the weight of the error change trend.

10. A variable displacement control method for a plunger pump with fast response and reduced pressure overshoot as claimed in claim 7, characterized in that: The temperature sensor (19) is used to collect the real-time temperature of the giant magnetostrictive actuator (1) as an input signal, and the temperature drift compensation value is added to the PID calculation result. Suppress the influence of thermal expansion of magnetostrictive materials, where T is the temperature collected in real time, T0 is room temperature, α=0.5um / ℃, and β=0.1um·s / ℃ are the characteristic coefficients of giant magnetostrictive materials.

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