A position-force feedback type electro-proportional axial piston pump variable mechanism

Abstract

This utility model relates to the field of swashplate axial piston pump technology, specifically to a position-force feedback electro-proportional axial piston pump variable displacement mechanism. It includes a pump housing, drive shaft, servo piston, swashplate, swashplate pin, slide rail, cylinder block, and piston-slide assembly. It also includes an adjuster housing, valve sleeve, slide valve, pilot spring, PF valve sleeve, PF piston, electromagnet, and feedback linkage. The electromagnet receives an electrical signal to drive a pressure change in the PF valve sleeve, which pushes the slide valve to allow hydraulic oil to enter the servo piston chamber. This drives the servo piston to adjust the swashplate tilt angle via the swashplate pin to regulate the displacement. The feedback linkage drives the valve sleeve to cut off the oil passage, achieving balance. This utility model, through its "electro-proportional drive + position-force feedback" design, achieves breakthroughs in structure, size, lifespan, control accuracy, and energy efficiency, overcoming the shortcomings of traditional hydraulic control systems and demonstrating significant technological advancement and practical value.

Description

Technical Field

[0001] This utility model relates to the field of swashplate axial piston pump technology, specifically to a position-force feedback electro-proportional axial piston pump variable mechanism. Background Technology

[0002] Swashplate axial piston pumps adjust the stroke of the piston slide assembly by changing the swashplate angle, thereby changing the displacement. The performance of its variable displacement mechanism directly affects the pump's efficiency and lifespan. Existing axial piston pumps mostly use a "hydraulic-controlled" variable displacement mechanism, which drives the components through pressure differences in the internal hydraulic circuit. This has the following drawbacks: first, it has a large number of internal transmission parts, a complex structure, and is difficult to assemble and maintain; second, it is large in size and weight, making it difficult to adapt to miniaturized hydraulic systems; and third, the long transmission links between parts are prone to wear and tear, leading to failures and shortening the service life of the variable displacement mechanism. Therefore, there is an urgent need for a variable displacement mechanism with a simplified structure, smaller size, and longer service life to overcome the shortcomings of existing technologies. Utility Model Content

[0003] The purpose of this invention is to provide a position-force feedback electro-proportional axial piston pump variable displacement mechanism. Through a structural design combining position-force feedback and electro-proportional control, it solves the problems of numerous parts, large size, and short lifespan in traditional hydraulic variable displacement mechanisms. To this end, this invention adopts the following technical solution: A position-force feedback electro-proportional axial piston pump variable mechanism includes a pump housing, a drive shaft rotatably connected to the pump housing, a servo piston slidably disposed within the pump housing, a swashplate rotatably connected to the pump housing, a swashplate pin with one end hinged to the servo piston and the other end fixed to the swashplate, a cylinder sleeved on the drive shaft and rotating synchronously therewith, and a piston-sliding assembly slidably disposed within the cylinder. The piston-sliding assembly fits against the slide rail, and the slide rail engages with the swashplate. Unlike existing technologies, it also includes an regulator housing fixed to the pump housing and a valve sleeve disposed within the regulator housing. The system includes a spool valve, a pilot spring and spring seat fitted at one end of the spool valve, a PF valve sleeve communicating with the regulator housing, a PF plunger slidably disposed within the PF valve sleeve, an electromagnet for receiving external electrical signals and driving changes in the hydraulic oil pressure within the PF valve sleeve, and a feedback link with one end connected to the servo piston via a cylindrical pin and the other end hinged to the valve sleeve; one end of the spool valve abuts against the spring seat, and the other end can contact the PF plunger; both the valve sleeve and the spool valve are provided with through holes, which can communicate with the oil passage of the regulator housing and the servo piston chamber of the pump housing.

[0004] Furthermore, the output thrust of the electromagnet is proportional to the strength of the external electrical signal, which can drive the internal valve core to move axially to adjust the hydraulic oil pressure in the PF valve sleeve.

[0005] Furthermore, the inclined pin is fixed to the swashplate by an interference fit, and a smooth, wear-resistant bushing is provided at the hinge point between the inclined pin and the servo piston.

[0006] Furthermore, the electromagnet is electrically connected to the external excavator system and can receive current or voltage signals output by the excavator system.

[0007] Furthermore, the PF valve sleeve is connected to the regulator housing by threads, and the mating surfaces of the two are provided with sealing rings.

[0008] Furthermore, it also includes a bracket for supporting the rotation of the swashplate, the bracket being fixed to the pump housing, and the swashplate being rotatably connected to the bracket's semicircular R-arc by its own semicircular R-arc.

[0009] Furthermore, one end of the drive shaft is supported on the pump housing by a cylindrical roller bearing, and the other end is supported by a needle roller bearing.

[0010] Furthermore, the clearance between the spool valve and the valve sleeve is 0.005-0.01mm to ensure the sealing performance of the hydraulic oil.

[0011] Furthermore, the initial pre-compression of the pilot spring is 1-3 mm, which is used to provide the initial reset force for the slide valve.

[0012] Compared with the prior art, the beneficial technical effects of this utility model are: 1. Simplified structure, making assembly and maintenance more convenient. Existing technologies employ complex hydraulic control circuits with numerous transmission parts, making assembly and maintenance difficult. This invention replaces the traditional hydraulic control circuit with an electromagnet and position-force feedback structure, reducing transmission parts, simplifying assembly steps, and requiring only inspection of core components such as the electromagnet, spool valve, and feedback linkage during later maintenance, significantly reducing maintenance costs and time.

[0013] 2. Lightweight and more adaptable Existing hydraulic variable displacement mechanisms are bulky and heavy due to redundant parts. This invention, through structural integration, reduces the overall size and weight of the variable displacement mechanism, making it directly adaptable to space- and weight-sensitive applications such as mini excavators and portable hydraulic equipment.

[0014] 3. Significantly extended lifespan and improved reliability Existing hydraulic control mechanisms have long transmission links, numerous wear points on parts, and an average lifespan of approximately 2000 hours. This invention shortens the transmission link, reducing 4-5 wear points; adds wear-resistant structures to key components; and uses "position-force feedback" to quickly cut off the oil passage, avoiding impact wear caused by excessive servo piston movement. These combined improvements increase the average lifespan of the mechanism and reduce the failure rate.

[0015] 4. High control precision and fast response speed Existing hydraulic variable displacement mechanisms rely on hydraulic signal transmission, with a displacement adjustment response time of approximately 0.5 seconds and an accuracy error of ±5%. This invention achieves linear control of "electrical signal-displacement" through direct drive of an electromagnet's electrical signal and mechanical position feedback, shortening the response time and improving displacement adjustment accuracy. Furthermore, stepless adjustment of the displacement can be achieved by adjusting the input current of the electromagnet, meeting the precise flow matching requirements of engineering machinery.

[0016] 5. Optimized energy efficiency and outstanding energy saving performance Existing hydraulic variable displacement mechanisms suffer from significant energy loss due to complex hydraulic circuits. This invention's electro-proportional control can precisely adjust the displacement according to load requirements, avoiding unnecessary flow output. Compared to traditional hydraulic control mechanisms, it is more energy-efficient, especially under low to medium flow conditions.

[0017] In summary, this utility model achieves breakthroughs in multiple dimensions such as structure, volume, lifespan, control precision, and energy efficiency through the innovative design of "electro-proportional drive + position-force feedback". It effectively solves the inherent defects of traditional hydraulic variable mechanisms and has significant technological progress and practical value. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of this utility model. Detailed Implementation

[0019] In the description of this utility model, it should be noted that the terms "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the paper. This orientation or positional relationship is only for the convenience of describing this utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0020] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "communication" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0021] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0022] like Figure 1 The position-force feedback type electro-proportional axial piston pump variable mechanism shown includes a pump housing 7, a drive shaft 1, a servo piston 4, a swashplate 3, a swashplate pin 5, a slide rail 19, a cylinder 17, a piston-slide assembly 18, a regulator housing 10, a valve sleeve 11, a slide valve 12, a pilot spring 15, a spring seat 14, a PF valve sleeve 8, a PF piston 9, an electromagnet 16, a feedback link 13, and a cylindrical pin 6. Drive shaft 1 is rotatably connected to pump housing 7. Cylinder body 17 is sleeved on drive shaft 1 and rotates synchronously with it. Sliding assembly 18 is slidably disposed in cylinder body 17 and fits against slide rail 19. Sliding rail 19 is fitted with swashplate 3. Servo piston 4 is slidably disposed in pump housing 7. One end of swashplate 5 is hinged to servo piston 4, and the other end is fixed to swashplate 3. Regulator housing 10 is fixed to pump housing 7. Valve sleeve 11 and slide valve 12 are disposed in regulator housing 10. Pilot spring 15 is sleeved on one end of slide valve 12. Spring seat 14 is far from pilot spring 15. The PF valve sleeve 8 is connected to the regulator housing 10, and the PF plunger 9 is slidably disposed in the PF valve sleeve 8. One end of the PF plunger 9 can contact the spool valve 12. The electromagnet 16 is used to receive external electrical signals and drive the hydraulic oil pressure change in the PF valve sleeve 8. One end of the feedback linkage 13 is connected to the servo piston 4 through the cylindrical pin 6, and the other end is hinged to the valve sleeve 11. Both the valve sleeve 11 and the spool valve 12 are provided with through holes, which can communicate with the oil passage of the regulator housing 10 and the servo piston chamber of the pump housing 7.

[0023] Work process An external electrical signal is input to the electromagnet 16, which drives the hydraulic oil pressure in the PF valve sleeve 8 to change, pushing the PF plunger 9 to contact the slide valve 12 and causing the slide valve 12 to move. When the slide valve 12 is aligned with the through hole of the valve sleeve 11, the hydraulic oil enters the servo piston chamber and drives the servo piston 4 to move. The servo piston 4 drives the swashplate 3 to rotate through the swashplate pin 5, changing the stroke of the swashplate assembly 18 to adjust the displacement. At the same time, the servo piston 4 drives the valve sleeve 11 to move through the feedback linkage 13, causing the through hole to be misaligned and cutting off the oil passage to achieve balance. In another preferred embodiment, the output thrust of the electromagnet 16 is proportional to the strength of the external electrical signal: when the input electrical signal is 0.3A, the output thrust is 15N; when the electrical signal increases to 0.6A, the thrust increases to 30N, which can linearly drive the internal valve core to move axially (stroke 0-5mm), accurately adjust the hydraulic oil pressure in the PF valve sleeve 8 (0-10MPa), and realize stepless proportional control of displacement. In another preferred embodiment, the swashplate 5 and the swashplate 3 are fixed with an interference fit, and a smooth, wear-resistant bushing is provided at the hinge between the swashplate 5 and the servo piston 4. The interference fit eliminates the need for additional fasteners, thus eliminating the risk of bolt loosening, avoiding swashplate tilt angle adjustment deviations caused by connection gaps, and reducing displacement fluctuations. The smooth, wear-resistant bushing reduces the friction coefficient at the hinge, reduces relative rotational resistance, makes the servo piston drive the swashplate to rotate more smoothly and avoids jamming, improving displacement adjustment responsiveness. At the same time, it avoids direct metal-to-metal wear between the swashplate and the servo piston, extending the maintenance cycle at the hinge. The combination of these two features also maintains the long-term transmission accuracy of the swashplate, ensuring stable displacement adjustment accuracy during long-term use of the mechanism, and meeting the needs of long-term stable operation of engineering machinery.

[0024] In another preferred embodiment, the electromagnet 16 is connected to the controller of the external excavator system via a shielded wire to receive a 0-1A current signal (or a 0-5V voltage signal). The excavator system adjusts the output signal in real time according to load requirements (such as digging resistance), enabling the electromagnet 16 to dynamically adjust the pump displacement to adapt to the flow requirements of different working conditions. In another preferred embodiment, the PF valve sleeve 8 and the regulator housing 10 are connected by an M16×1.5 thread, and an O-ring (made of nitrile rubber, wire diameter 1.8mm) is provided on the mating surface of the two. During assembly, thread sealant (model Loctite 567) is applied to the thread, and the tightening torque is 25 N·m to ensure that there is no leakage of hydraulic oil and the sealing pressure reaches more than 20 MPa. In another preferred embodiment, a bracket 2 (made of Q235 steel) is added. The bracket 2 is fixed to the pump housing 7, and the swashplate 3 is rotatably connected to the bracket 2 via its own semi-circular R-arc. The Q235 steel bracket provides stable support and is suitable for the overall stress requirements of the pump body. Compared with the traditional pin connection, the semi-circular R-arc connection not only has a larger contact area, which can effectively limit the radial wobble of the swashplate 3 during rotation and improve the rotational stability of the swashplate, but also allows the swashplate to slide smoothly along the arc surface, reducing the risk of rotational jamming. At the same time, it avoids the local wear problem that is prone to occur with pin connections, extends the service life of the swashplate and the bracket, and eliminates the need for additional pin assembly, simplifying the overall assembly process and further ensuring the long-term operational stability of the mechanism. In another preferred embodiment, one end of the drive shaft 1 is supported on the pump housing 7 by a cylindrical roller bearing, and the other end by a needle roller bearing. The cylindrical roller bearing can effectively withstand the large radial load generated when the drive shaft rotates, preventing deformation of the drive shaft due to load concentration; the needle roller bearing, with its compact structure, fits the limited installation space within the pump housing 7, while providing stable support for the other end of the drive shaft. The combined use of the two bearings can reduce radial runout when the drive shaft rotates, ensure the accuracy of synchronous rotation of the cylinder with the drive shaft, avoid abnormal contact between the swashplate and the sliding assembly, reduce the wear risk of the bearings themselves, extend the service life of the drive shaft and bearings, and further ensure the stability of the entire variable mechanism operation.

[0025] In another preferred embodiment, the clearance between the slide valve 12 and the valve sleeve 11 is 0.005-0.008 mm. Precision grinding (dimensional tolerance IT5 grade, roundness ≤0.002 mm) ensures the sealing performance of the hydraulic oil, thereby guaranteeing the accuracy of displacement changes.

[0026] In another preferred embodiment, the initial pre-compression of the pilot spring 15 is 2mm (free length 25mm, assembled length 23mm). The spring is made of 60Si2Mn material and has undergone low-temperature tempering treatment, with an elastic coefficient deviation of ≤5%, which can ensure the stability of the reset force of the slide valve 12 (initial elastic force 10N) and improve the consistency of feedback balance. The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A position-force feedback type electro-proportional axial piston pump variable mechanism, comprising a pump housing (7), a drive shaft (1) rotatably connected to the pump housing (7), a servo piston (4) slidably disposed within the pump housing (7), a swashplate (3) rotatably connected to the pump housing (7), a swashplate pin (5) with one end hinged to the servo piston (4) and the other end fixed to the swashplate (3), a cylinder (17) sleeved on the drive shaft (1) and rotating synchronously therewith, and a piston-sliding assembly (18) slidably disposed within the cylinder (17), wherein the piston-sliding assembly (18) fits against a slide rail (19), and the slide rail (19) engages with the swashplate (3), characterized in that, It also includes a regulator housing (10) fixed to the pump housing (7), a valve sleeve (11) and a slide valve (12) disposed in the regulator housing (10), a pilot spring (15) and a spring seat (14) sleeved on one end of the slide valve (12), a PF valve sleeve (8) communicating with the regulator housing (10), and a PF plunger (9) slidably disposed in the PF valve sleeve (8) for receiving external electrical signals and driving the hydraulic oil pressure in the PF valve sleeve (8). The variable electromagnet (16) and the feedback link (13) with one end connected to the servo piston (4) via a cylindrical pin (6) and the other end hinged to the valve sleeve (11); one end of the slide valve (12) abuts against the spring seat (14) and the other end can contact the PF plunger (9); both the valve sleeve (11) and the slide valve (12) are provided with through holes, which can communicate with the oil passage of the regulator housing (10) and the servo piston chamber of the pump housing (7).

2. The position-force feedback electro-proportional axial piston pump variable mechanism according to claim 1, characterized in that, The output thrust of the electromagnet (16) is proportional to the strength of the external electrical signal, which can drive the internal valve core to move axially to adjust the hydraulic oil pressure in the PF valve sleeve (8).

3. The position-force feedback electro-proportional axial piston pump variable mechanism according to claim 1, characterized in that, The inclined pin (5) is fixed to the swashplate (3) by an interference fit, and a smooth wear-resistant bushing is provided at the hinge of the inclined pin (5) and the servo piston (4).

4. The position-force feedback electro-proportional axial piston pump variable mechanism according to claim 1, characterized in that, The electromagnet (16) is electrically connected to the external excavator system and can receive current or voltage signals output by the excavator system.

5. The position-force feedback electro-proportional axial piston pump variable mechanism according to claim 1, characterized in that, The PF valve sleeve (8) is connected to the regulator housing (10) by threads, and the mating surfaces of the two are provided with sealing rings.

6. The position-force feedback electro-proportional axial piston pump variable mechanism according to claim 1, characterized in that, It also includes a bracket (2) for supporting the rotation of the swash plate (3), the bracket (2) being fixed to the pump housing (7), and the swash plate (3) being rotatably connected to the bracket (2) through its own semicircular R-arc.

7. The position-force feedback electro-proportional axial piston pump variable mechanism according to claim 1, characterized in that, The drive shaft (1) is supported on the pump housing (7) by a cylindrical roller bearing at one end and a needle roller bearing at the other end.

8. The position-force feedback electro-proportional axial piston pump variable mechanism according to claim 1, characterized in that, The clearance between the slide valve (12) and the valve sleeve (11) is 0.005-0.01mm to ensure the sealing performance of the hydraulic oil.

9. The position-force feedback electro-proportional axial piston pump variable mechanism according to claim 1, characterized in that, The initial pre-compression of the pilot spring (15) is 1-3 mm, which is used to provide the initial reset force for the slide valve (12).

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