Compact power unit and electro-hydraulic actuator

Abstract

The utility model discloses a compact type power unit and electro-hydraulic actuator, including the motor subassembly for providing power, be used for outputting the plunger pump subassembly of hydraulic power, be used for containing the oil tank of hydraulic medium, the motor subassembly includes drive shaft, stator subassembly, rotor subassembly, motor front end cover, plunger pump subassembly is completely contained in the oil tank, the plunger pump assembly comprises a pump body, a valve plate, a cylinder body and a swash plate, the shaft extension end of the driving shaft is directly inserted into a rotation center hole, a cantilever at the shaft extension end of the driving shaft supports the cylinder body and drives the cylinder body to synchronously run through a key, the cylinder body abuts against the valve plate under the action of hydraulic pressure, the valve plate is supported on the pump body, and the swash plate is supported on the pump body. The end of a pump body of the plunger pump assembly is fixedly connected with a motor front end cover of the motor assembly, and the pump body is provided with an oil inlet opening towards an inner cavity of the oil tank so that a pump body cavity can be communicated with the inner cavity of the oil tank. The power unit is compact in structure, high in power density and low in manufacturing cost.

Description

Technical Field

[0001] This utility model belongs to the field of hydraulic transmission and control technology, and specifically relates to a compact power unit and an electro-hydraulic actuator. Background Technology

[0002] Existing hydraulic systems mostly employ centralized valve control systems, which offer advantages such as fast response and high precision. However, they also suffer from problems such as large throttling losses, low system efficiency, numerous and complex pipelines, and severe system overheating. For example, drive systems employing an engine-variable pump-multi-way valve-actuator or an electric motor-variable pump-multi-way valve-actuator, where the engine or electric motor drives the hydraulic pump and the multi-way valve distributes hydraulic energy to various actuators, typically have the following characteristics:

[0003] (1) The existing centralized hydraulic system is based on the open valve control principle. A large amount of energy is consumed in the throttling orifice and overflow. At the same time, there are a large amount of friction loss and local loss in this process, namely pressure loss caused by pipeline and hydraulic valve. The overall efficiency of the hydraulic system is about 30%. A large amount of hydraulic energy is lost and converted into heat energy, causing the system to heat up. The system efficiency is low.

[0004] (2) Existing centralized hydraulic system drive system has a long centralized pressure oil drive pipeline, a large amount of oil consumption, and requires an additional oil tank and cooling device, which further increases the system volume and cost.

[0005] (3) Traditional hydraulic power systems are bulky, have an inefficient structure, generate a lot of vibration and noise, have many connecting pipes and interfaces, are prone to oil leaks, and pollute the environment.

[0006] Distributed pump-controlled hydraulic systems (DPHS) are a relatively new type of hydraulic system, especially with the development of electrification. DPHS will become an important technological trend in the future to match electrification. The most important component of a DPHS system is the electro-hydraulic actuator (EHA), which integrates the motor, hydraulic pump, and oil tank, directly using a pump-controlled actuator. The EHA embodies the trend of high integration between hydraulic components and electric motor control, fully leveraging the high power-to-weight ratio of hydraulics and the control advantages of electric motors.

[0007] The core component of an electro-hydraulic actuator (EHA) is the power unit that provides hydraulic power, and currently, it mainly faces the following problems:

[0008] (1) The existing electro-hydraulic actuator (EHA) power unit consists of a motor, hydraulic pump, coupling, oil tank, hydraulic valve and other parts that are simply integrated together in series and parallel. Each component occupies a large volume space and has a large weight, resulting in a relatively low overall power-to-weight ratio.

[0009] (2) Most of the hydraulic pumps used in the existing electro-hydraulic actuator (EHA) power units are gear pumps, and their working pressure is generally below medium pressure. Therefore, they are difficult to meet the requirements of long-term use in engineering machinery and other fields that require high-pressure operation.

[0010] (3) The hydraulic reversal in the existing electro-hydraulic actuator (EHA) power unit is achieved by the motor, which can rotate in both directions. The repeated high-frequency reversal of the motor under high speed conditions and high rotational inertia can easily lead to motor damage. At the same time, the hydraulic pump is a hydraulic pump that can work in four quadrants. Therefore, the overall price is high and difficult to afford in the field of engineering machinery.

[0011] (4) The piston pumps used in some existing electro-hydraulic actuator (EHA) power units are generally slipper-type swashplate piston pumps. Due to inherent defects in the structural design of these piston pumps, there are unbalanced forces and torques in the friction pairs, which can easily lead to problems such as lateral force overturning, wear and burning of the disc. Especially when used in conjunction with a high-speed motor, the wear and failure of the piston pump is aggravated. At the same time, the slipper-type piston pumps used have poor high-speed and low-speed performance and cannot be matched with the wide speed range of the motor. Utility Model Content

[0012] This utility model discloses a compact power unit and an electro-hydraulic actuator. The purpose is to provide a new type of power unit and electro-hydraulic actuator that is highly compact, small in size, light in weight, low in noise, highly efficient and energy-saving, high in power density and low in price, in order to address the problems existing in current power units and electro-hydraulic actuators in distributed hydraulic systems.

[0013] To achieve the above objectives, the present invention adopts the following compact power unit design:

[0014] A compact power unit includes:

[0015] The motor assembly provides driving force and drives the plunger pump assembly; the front end of the drive shaft of the motor assembly extends from the front cover of the motor and forms a shaft extension end;

[0016] A plunger pump assembly, in conjunction with a motor assembly, outputs hydraulic power. The plunger pump assembly includes a pump body directly connected to the motor assembly. It also includes a distribution pair and a sliding plate pair. The pump body houses several plungers, one end of which engages with a cylinder block, and the other end engages with a swashplate via a sliding plate and a pressure plate. A shaft extension, in a cantilevered state, directly inserts into and supports the cylinder block. The shaft extension, in conjunction with the cylinder block, drives the plungers and sliding plate to rotate, achieving reciprocating motion for oil suction and pressure. Low-pressure oil enters the plunger bore from the distribution pair and / or the sliding plate pair and exits from the sliding plate pair. The plunger pump assembly is also connected to a control valve group to control the on / off state of the hydraulic oil supply pipeline.

[0017] The oil tank is used to contain hydraulic oil and supply oil to the piston pump assembly. The shaft extension end extends into the oil tank and the piston pump assembly is located in the oil tank and submerged in hydraulic oil. The pump body is provided with an oil inlet that connects to the oil tank.

[0018] The aforementioned compact power unit operates by energizing the motor assembly, which drives the plunger pump assembly to perform oil suction and pressure processes. The plunger pump assembly is submerged in an oil tank, allowing for continuous oil suction with low noise, while simultaneously delivering high-pressure hydraulic fluid for continuous drive output, ensuring smooth operation of external loads. The hydraulic oil in the tank submerges the pump body, which has an inlet to allow hydraulic fluid to enter the pump body cavity. After the plunger's suction and pressure actions, high-pressure hydraulic oil is delivered as the driving medium.

[0019] Furthermore, in this invention, the motor assembly can be constructed in various forms and is not limited to a single one. Here, we propose an optimized and feasible option: the motor assembly includes a motor housing, one end of which is closed by a front cover; the drive shaft is located inside the motor housing and a rotor assembly is connected to it; a stator assembly corresponding to the rotor assembly is provided on the inner surface of the motor housing; the front part of the drive shaft engages with the motor housing via a first bearing, and the rear part of the drive shaft engages with the motor housing via a second bearing. With this design, the motor assembly also includes an encoder and a controller to achieve precise control and ensure accurate and effective power output.

[0020] Furthermore, in this invention, the motor assembly operates continuously, and the hydraulic oil in the tank is continuously compressed and transported, causing the hydraulic oil temperature to rise. To avoid the impact of high temperature on the motor assembly, it is necessary to control the motor assembly temperature. This can be achieved through various methods, and is not limited to a single one. Here, we optimize and propose one feasible option: a heat-insulating sealing gasket is provided between the motor assembly and the tank and / or between the motor assembly and the pump body. The heat-insulating sealing gasket is used to prevent the external temperature of the motor assembly from being conducted to the interior of the motor assembly. When this solution is adopted, the heat-insulating sealing gasket can separate the motor assembly from the tank to reduce heat transfer, and can also separate the motor assembly from the pump body to reduce heat transfer, thereby preventing the motor assembly temperature from becoming too high. Alternatively, a heat dissipation structure can be used to dissipate heat from the motor assembly to control the temperature.

[0021] Furthermore, to ensure the safe and reliable operation of the motor assembly and prevent hydraulic oil from entering and damaging it, the sealing structure of the motor assembly can be optimized. The specific sealing structure is not limited to a single design; one feasible option is proposed here: an oil seal assembly is installed between the drive shaft and the front end cover of the motor, with the opening of the oil seal assembly facing the plunger pump assembly. When using this solution, a skeleton oil seal can be used, which improves the sealing performance between the motor housing and the drive shaft, preventing external hydraulic oil from entering the motor housing along the drive shaft.

[0022] Furthermore, when the motor assembly drives the plunger pump assembly to rotate for oil suction, the corresponding plunger pump assembly structure can be constructed in various forms and is not limited to a single one. Here, we optimize and propose one feasible option: the cylinder body is provided with plunger holes corresponding to the plungers one-to-one. The plungers enter the plunger holes from the rear end face of the cylinder body and slide back and forth relative to the plunger holes. The plunger holes extend through to the front end face of the cylinder body and are covered by a distribution plate on the front end face of the cylinder body. The distribution plate is provided with a low-pressure distribution port. The cylinder body rotates relative to the distribution plate, and oil suction occurs when the plunger holes connect to the low-pressure distribution port. With this scheme, the low-pressure distribution port on the distribution plate serves as an oil inlet structure, helping hydraulic oil to better enter the plunger holes and improving oil suction efficiency.

[0023] Furthermore, in this invention, a sliding plate and a plunger are designed to work together. During the synchronous rotation of the cylinder block and the sliding plate, the plunger is driven to reciprocate, allowing it to switch between oil suction and oil pressure states. The structure of the sliding plate is not limited to a single type; an optimization is proposed, and one feasible option is as follows: The front end face of the sliding plate has plunger ball sockets corresponding to the plungers. These ball sockets extend through a waist-shaped hole in the sliding plate to the rear end face. The rear end face of the sliding plate also has a sealing structure and an oil draining structure. The pressure plate is fitted to the sliding plate and has a pressure plate hole corresponding to the plunger ball socket. The pressure plate hole engages with the plunger to ensure that the end of the plunger is always within the plunger ball socket. With this design, as the pressure plate and the sliding plate rotate synchronously on the swashplate, the plunger is pulled out of or pushed into the plunger hole by the plunger ball socket, thus achieving the oil suction and oil pressure actions.

[0024] Furthermore, in this invention, the swashplate structure can be constructed in various forms and is not limited to a single one. Here, we optimize and propose one feasible option: the swashplate is provided with an inclined surface for the sliding plate to be placed at an angle. The swashplate is provided with a low-pressure port and a high-pressure port that penetrate and connect to the inclined surface. The low-pressure port is connected to the pump body cavity and is submerged in hydraulic oil, while the high-pressure port is connected to the oil outlet on the rear end cover of the pump body. When the sliding plate rotates to the plunger waist-shaped hole connected to the low-pressure port, oil is drawn in; when the sliding plate rotates to the plunger waist-shaped hole connected to the high-pressure port, oil is discharged. With this scheme, oil enters at the low-pressure port of the swashplate and is drawn into the plunger hole, which is a synchronous action with the oil drawn into the plunger hole from the low-pressure port of the distribution plate. When rotating to the discharge position, the distribution plate closes one end of the plunger hole, and the hydraulic oil in the plunger hole can only be discharged from the high-pressure port of the swashplate, thereby realizing the external delivery of high-pressure oil as a driving medium.

[0025] In this invention, the connection and fit structure of the sliding plate, pressure plate, and swashplate is not limited to a single type and can be constructed in various feasible ways. Here, we optimize and propose one feasible option: the sliding plate and swashplate are connected and fitted through a locking structure. The locking structure includes a locking member connected to the swashplate. From its front end to its rear end, the locking member includes, in sequence, a locking member positioning part aligned with the swashplate, a locking member connecting part fixed to the swashplate, and a rotary fitting part connected and fitted to the pressure plate and sliding plate. The rear end of the locking member is secured by a limiting structure to keep the pressure plate, sliding plate, and swashplate tightly fitted. The limiting structure is installed to the locking member through a connecting member or is integrally formed with the locking member. With this solution, the locking structure presses the pressure plate tightly against the sliding plate, and the sliding plate presses tightly against the swashplate, maintaining a tight fit throughout the rotation process. In this solution, the locking member can be removed from the swashplate. When the locking member wears out after a certain period of use, it can be directly replaced, avoiding the need to replace the swashplate and thus reducing maintenance costs.

[0026] In this invention, the connection and fit structure of the sliding plate, pressure plate, and swashplate is not limited to a single type and can be constructed in various feasible ways. Here, we optimize and propose another feasible option: the sliding plate and swashplate are connected and fitted through a locking structure. The locking structure includes a rotary fitting part that protrudes from the surface of the swashplate and forms a cylindrical protrusion. Both the pressure plate and the sliding plate are connected and fitted to the rotary fitting part and rotate along the rotary fitting part. The top of the rotary fitting part is secured by a limiting structure to keep the pressure plate, sliding plate, and swashplate in close contact. The limiting structure is installed to the rotary fitting part through a connector. With this solution, the locking structure and the swashplate are integrally formed, ensuring the integrity of the locking structure and the swashplate. After connecting the sliding plate and pressure plate, the rotational direction is maintained, preventing loosening and detachment, thereby improving the reliability of the plunger pump assembly during operation.

[0027] In this invention, the connection and cooperation structure of the slide, pressure plate, and swashplate is not limited to a single one and can be constructed in a variety of feasible options. Here, we optimize and propose another feasible option: the slide and swashplate are connected and cooperated by a locking structure. The locking structure includes a locking member, a locking member bolt, a locking member disc spring, and a locking member limiting pin. The locking member is provided with a rotating engagement part and a locking member positioning part. A limiting plate that cooperates with the pressure plate and slide is provided between the locking member and the pressure plate. The locking member and the limiting plate are either separate structures or connected and fixed into an integral structure. A locking member disc spring is provided between the locking member bolt and the limiting plate. A locking member limiting pin is provided between the locking member positioning part and the swashplate to limit the rotation of the locking member. The locking member bolt passes through the locking member and is fixedly connected to the swashplate.

[0028] Furthermore, the locking element is fixed to the swashplate by a threaded structure or an interference fit; the locking structure connects the slide plate and the pressure plate through a sliding bearing, and the rotary mating part is provided with at least one oil drain groove for draining the high-pressure oil leaking from the slide plate and the pressure plate and for lubricating the sliding bearing. The oil drain groove can be configured in a radial or spiral shape.

[0029] Furthermore, in this invention, the cylinder body is connected to the shaft extension end. During rotation, the cylinder body should maintain a stable position to ensure the smooth and reliable operation of the plunger pump assembly. Smooth cylinder operation can be achieved in various ways; here, an optimization is proposed, and one feasible option is suggested: the cylinder body is provided with a rotation center hole for connecting the shaft extension end. The shaft extension end passes through the rotation center hole and is equipped with a fastener and a blocking plate at its end. An elastic preload is provided between the blocking plate and the rotation center hole, applying an elastic preload force to the cylinder body. With this solution, the fastener can be a bolt, the blocking plate can be a circular baffle, and the elastic preload can be a spring.

[0030] The above describes the structure of the compact power unit. This utility model also introduces an electro-hydraulic actuator using this compact power unit, which will be described below.

[0031] An electro-hydraulic actuator includes the compact power unit described above. Specifically, the oil outlet structure of the compact power unit is connected to an oil distribution pipeline, which is connected to a hydraulic cylinder assembly for driving a load. The hydraulic cylinder assembly includes a cylinder barrel, a piston rod disposed inside the cylinder barrel, and the piston rod divides the cylinder barrel into two actuating chambers. Each actuating chamber is provided with an oil inlet structure and an oil outlet structure. The oil distribution pipeline is respectively connected to the oil inlet structures of the two actuating chambers and the oil inlet is controlled by a control valve. The front end of the piston rod is provided with a drive connection structure for connecting to and driving the load.

[0032] The electro-hydraulic actuator described above drives a piston rod to reciprocate through hydraulic oil supplied by a compact power unit, thereby driving the load. Since the compact power unit operates in one direction, the control valve includes at least a directional valve or a directional throttle valve to distribute the hydraulic oil output.

[0033] Furthermore, in this invention, the structure of the piston rod is not limited to a single type. Here, an optimization is proposed, and one feasible option is suggested: the piston rod is a single-acting rod, with the piston positioned at the rear end of the piston rod to divide the cylinder into a rod-side chamber and a rodless chamber. The port of the rod-side chamber is equipped with a guide seat to guide the sliding direction of the piston rod, and the port of the rodless chamber is equipped with a connecting block for sealing. With this design, the guide seat slides with the piston rod, and several sealing rings are provided between the guide seat and the sliding rod.

[0034] Furthermore, this paper proposes an alternative feasible option for the piston rod: the piston rod is a double-acting rod, with the piston positioned in the middle of the piston rod to divide the cylinder into two rod-bound chambers. Guide seats are provided at both ends of the cylinder to guide the piston rod's sliding. Drive connection structures are provided at both ends of the piston rod to connect to and drive the load. With this design, loads can be placed on both sides of the cylinder, and the reciprocating motion of the piston rod can drive the loads on both sides.

[0035] Compared with the prior art, some of the beneficial effects that this utility model can achieve include:

[0036] The power unit disclosed in this utility model outputs power by driving a piston pump assembly with a motor. It has a compact structure, stable operation, higher power density, and can ensure the reliability of output while reducing overall cost. Attached Figure Description

[0037] Figure 1 This invention relates to a compact electro-hydraulic actuator.

[0038] Figure 2 for Figure 1 The compact power unit in the system.

[0039] Figure 3 This is a structural diagram of the plunger pump assembly in this utility model.

[0040] Figure 4 for Figure 3 AA section view.

[0041] Figure 5 This is a schematic diagram of the end face structure of the slide plate in this utility model.

[0042] Figure 6 In this utility model Figure 5 CC cross-section view.

[0043] Figure 7 This is a schematic diagram of the other end face of the slide plate in this utility model.

[0044] Figure 8 This is a schematic diagram of the distribution plate in this utility model.

[0045] Figure 9 This is a schematic diagram of the swashplate and pin shaft on one side of the present invention.

[0046] Figure 10 In this utility model Figure 9 DD cross-section view.

[0047] Figure 11 This is a schematic diagram of the other side of the swashplate and pin in this utility model.

[0048] Figure 12 This is a schematic diagram of the pin shaft in this utility model.

[0049] Figure 13 This is a cross-sectional view of the integrated swashplate and pin shaft structure of this utility model.

[0050] Figure 14 The slide block pair structure in this utility model adopts an integrated limiting structure.

[0051] Figure 15 This is a diagram of the integrated limiting structure in this utility model.

[0052] Figure 16 This is another embodiment of the limiting structure in this utility model.

[0053] Marked in the image:

[0054] 1. Motor assembly; 2. Thermal insulation gasket; 3. Piston pump assembly; 4. Oil tank; 4a. Oil tank inner cavity; 5. Control valve; 6. Hydraulic cylinder assembly; 6a. Cylinder barrel; 6b. Piston rod; 6c. Guide seat; 6d. Piston; 6e. Connecting block; 6g. Rod chamber; 6h. Rodless chamber; 10. Drive shaft; 10a. Shaft extension end; 11. Motor stator assembly; 12. Motor rotor assembly; 12a. Permanent magnet; 13. First bearing; 14. Second bearing; 15. Motor housing; 16. Motor front end cover; 17. Skeleton oil seal; 18. Encoder; 19. 10. Controller; 20. Fastener; 21. Baffle plate; 22. Elastic preload; 31. Pump body; 32. Rear end cover; 33. Oil inlet; 32b. Oil outlet; 35. Pump body cavity; 40. Swashplate; 41. Swashplate support surface; 41a. Swashplate center hole; 42. Swashplate back side; 42a. Swashplate positioning hole; 42b. Swashplate drain groove; 42c. Bolt connection hole; 42d. Pin positioning hole; 43. Swashplate opening groove; 44. Swashplate low-pressure port; 44a. Swashplate low-pressure port triangular groove; 45. Swashplate high-pressure port; 45a. Swashplate high-pressure port triangular groove; 4 5b. Spacer; 46. Attaching element; 46a. Rotary mating part; 46b. Attaching element connecting part; 46c. Attaching element positioning part; 46d. Attaching element oil drain groove; 46e. Socket hexagonal hole; 46f. Attaching element bolt hole; 46g. Attaching element disc spring; 46h. Attaching element limit pin; 47. Limiting plate; 47a. Limiting plate oil drain groove; 47b. Limiting plate oil drain hole; 48. Limiting bolt; 50. Slide plate; 51. Slide plate hydrostatic support surface; 52. Slide plate center hole; 52a. Sliding bearing; 53. Slide plate oblong hole; 54. Slide plate outer sealing part; 5 5. Inner sealing part of the sliding plate; 56. Spacing sealing part of the sliding plate; 57. Auxiliary support surface of the sliding plate; 57a. Annular oil drain groove of the sliding plate; 57b. Radial oil drain groove of the sliding plate; 58. Plunger ball socket; 60. Pressure plate; 61. Center support surface of the pressure plate; 70. Plunger; 71. Plunger ball head; 72. Center hole of the plunger; 73. Tapered rod part; 74. Plunger part; 80. Cylinder block; 81. Plunger hole; 82. Waist-shaped hole of the cylinder block; 83. Rotation center hole; 84. Preload groove; 90. Distribution plate; 91. Static pressure support surface; 92. Low-pressure distribution port; 93. Triangular groove of the distribution plate. Detailed Implementation

[0055] The present invention will now be described in detail with reference to the accompanying drawings.

[0056] Although this invention allows for various embodiments, this specification and drawings only disclose certain specific forms as exemplified by this invention. However, this invention is not intended to be limited to the described embodiments. The scope of this invention is set forth in the appended claims.

[0057] For ease of description, embodiments of the present invention are shown in a typical orientation such that when the central axis of the drive shaft of the power unit or electro-hydraulic actuator is horizontally positioned, with the motor assembly side on the left and the plunger pump assembly side on the right, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "horizontal," "bottom," "inner," and "outer" used in the description are all used with reference to this position and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or a specific orientation construction and operation. It should be understood that the present invention can be manufactured, stored, transported, used, and sold in orientations other than those described.

[0058] Example 1

[0059] like Figure 1 The diagram illustrates a compact electro-hydraulic actuator of this invention. The actuator includes a hydraulic cylinder assembly 6 for driving a load, a motor assembly 1 for providing power, a piston pump assembly 3 for outputting hydraulic power, and an oil tank 4 for containing hydraulic fluid. The hydraulic cylinder assembly 6 includes a cylinder barrel 6a, a piston rod 6b, a guide seat 6c, a piston 6d, and a connecting block 6e. The piston 6d divides the cylinder barrel 6a into a rod chamber 6g or a rodless chamber 6h. The connecting block 6e is fixedly connected to the cylinder barrel 6a. The piston pump assembly 3 is housed within the inner cavity 4a of the oil tank. The motor assembly 3 and the piston pump assembly 4 share a drive shaft 10. The high-pressure hydraulic fluid output by the piston pump assembly 3 is delivered to the rod chamber 6g or the rodless chamber 6h of the cylinder barrel via a control valve assembly 5, thereby achieving the extension and retraction of the piston rod 6b.

[0060] The motor assembly 1 operates in one direction. The control valve 5 includes at least a directional valve or a directional throttle valve. The working ports (A and B ports) of the control valve 5 are connected to the rod chamber 6g or rodless chamber 6h of the actuator. The oil inlet (P port) of the control valve 5 is connected to the outlet 32b of the plunger pump assembly. During operation, the low-pressure oil in the inner cavity 4a of the oil tank enters the pump body cavity 35 through the oil inlet 33. The oil in the pump body cavity 35 enters the plunger pump assembly 3 and, under its action, delivers high-pressure oil to the rod chamber 6g or rodless chamber 6h of the hydraulic cylinder assembly 6 through the control valve 5. The control valve 5 is used to control the extension and retraction of the piston rod 6b. Predictably, the control valve 5 may also include a flow valve for flow control and a pressure valve for pressure control.

[0061] As can be seen from the above structure, volumetric speed regulation is achieved by relying on the unidirectional speed change of the motor assembly and the oil reversing is realized through the reversing valve. This structure can significantly reduce the overall cost on the one hand, and avoid motor damage caused by repeated high-frequency reversing under high-speed conditions with high rotational inertia on the other hand.

[0062] It should be noted that this embodiment shows an asymmetrical single-rod hydraulic cylinder. It can be predicted that this invention is also applicable to symmetrical double-rod hydraulic cylinders.

[0063] The core component of a compact electro-hydraulic actuator is the power unit, which determines the actuator's performance. Figure 2 As shown, this is a compact power unit of the present invention, comprising a motor assembly 1 for providing power, a plunger pump assembly 3 for outputting hydraulic power, and an oil tank 4 for containing hydraulic medium. The motor assembly 1 includes a drive shaft 10, a stator assembly 11, a rotor assembly 12, and a motor front end cover 16. The plunger pump assembly 3 is completely housed inside the oil tank 4. The plunger pump assembly 3 includes a pump body 31, a distribution plate 90, a cylinder body 80, and a swashplate 40. The shaft extension end 10a of the drive shaft 10 is directly inserted into the rotation center hole 83. The shaft extension end 10a of the drive shaft 10 cantilever supports the cylinder body 80 and drives the cylinder body to rotate synchronously through a key. The cylinder body 80 abuts against the distribution plate 90 under hydraulic pressure. The distribution plate 90 is supported on the pump body 31. The end of the pump body 31 is fixedly connected to the motor front end cover 16 of the motor assembly 1. The pump body 31 is provided with an oil inlet 33 that opens into the inner cavity 4a of the oil tank, so that the pump body cavity 35 communicates with the inner cavity 4a of the oil tank.

[0064] A skeleton oil seal 17 is provided between the drive shaft 10 and the front cover 16 of the motor, with the opening of the skeleton oil seal 17 facing the plunger pump assembly.

[0065] A heat-insulating sealing gasket 2 is provided between the front cover 16 of the motor and the pump body 31 or / and between the front cover 16 of the motor and the oil tank 4 pump body to prevent the high temperature of the oil tank from being conducted to the motor assembly 1.

[0066] The motor assembly 1 includes a stator assembly 11 and a rotor assembly 12, with a certain air gap maintained between them to ensure a reasonable power factor and starting performance during motor operation. The rotor assembly 12 is fixedly connected to the drive shaft 10, which is supported on a first bearing 13 and a second bearing 14 at both ends. Preferably, the first bearing 13 or the second bearing 14 is configured to withstand a certain axial load to meet the preload applied by the plunger pump assembly 3 at the drive shaft extension end 10a. For example, tapered roller thrust bearings and deep groove ball thrust bearings are preferred. It should be noted that the motor assembly 1 can be, but is not limited to, an induction asynchronous motor, a permanent magnet DC motor, or a permanent magnet synchronous motor. Preferably, the motor assembly is a permanent magnet synchronous motor, and the rotor assembly 12 of the motor assembly includes at least permanent magnets 12a distributed on its outer circumferential surface. In another preferred embodiment, the motor is an induction asynchronous motor, including existing squirrel-cage asynchronous motors and wound-rotor asynchronous motors. The motor assembly 1 includes a stator assembly 11 and a rotor assembly 12. The stator assembly 11 includes components such as a stator core and stator windings. The stator core is a component of the motor's magnetic circuit and electrical circuit, and is formed by stamping and stacking thin silicon steel sheets coated with insulating varnish. Its outer circumference is fixedly connected to the motor housing 15. The stator windings are wound with insulated copper wire or insulated aluminum wire. The lead-out ends of the stator windings are led to lead-out holes provided on the motor housing 15 and connected to the controller 19. The other end of the drive shaft is connected to an encoder 18, and the encoder 18 signal is transmitted to the controller 19 through a data line.

[0067] like Figure 3 As shown, the plunger pump assembly 3 is a sliding disc type non-through shaft structure, including a pump body 31, a swashplate 40, a sliding disc 50, a pressure plate 60, a plunger 70, a cylinder 80, a distribution plate 90, and a rear end cover 32. The axis of the drive shaft 10 coincides with the axis of the cylinder 80. The shaft extension end 10a of the drive shaft 10 extends out of the front motor cover 16 of the motor housing 15. The shaft extension end 10a of the drive shaft 10 cantilever supports the cylinder 80 and is connected to the cylinder 80 through a spindle spline. The drive shaft 10 drives the cylinder 80 to rotate synchronously. The plunger 70 reciprocates in the plunger hole 81 of the cylinder 80 to realize the pump's suction and pressure oil operation.

[0068] The pump body 31 and the rear end cover 32 are fixedly connected by bolts. The pump body 31 is also provided with an oil inlet 33, which opens into the inner cavity 4a of the oil tank. The pump body 31 has a pump body cavity 35, which is connected to the inner cavity 4a of the oil tank through the oil inlet 33. The rear end cover 32 is provided with an oil outlet 32b and a control valve 5. The inlet of the control valve is connected to the oil outlet 32b. Preferably, the control valve 5 is a directional valve to control the direction of the oil. Predictably, the control valve 5 may also include, but is not limited to, a flow valve for controlling the flow rate of the oil and a pressure valve for controlling the pressure.

[0069] The sliding plate assembly is a key core component of the plunger pump assembly, including a swashplate 40 and a sliding plate 50 supported on the swashplate 40. In this embodiment, the sliding plate 50 has an integral disc structure, and a hydrostatic support exists between the sliding plate 50 and the swashplate 40. A hydrostatic support surface 51 is provided on the end face of the sliding plate 50 opposite to the swashplate 40. The hydrostatic support surface 51 has a sliding plate waist-shaped hole 53. The hydrostatic support surface 51 and the swashplate 40 maintain a sliding fit and form a clearance fit hydrostatic oil film support. Multiple waist-shaped sliding plate holes 53 are provided on the hydrostatic support surface 51. Preferably, the sliding plate waist-shaped holes 53 are evenly distributed on the hydrostatic support surface 51 with the sliding plate axis as the center. The sliding plate waist-shaped holes 53 communicate with the plunger ball socket 58. Preferably, the number of sliding plate waist-shaped holes 53 and plunger ball sockets 58 is set to 7 or 9. Figure 5 , Figure 6 , Figure 7 As shown.

[0070] An effective hydrostatic oil film support is formed between the hydrostatic support surface 51 and the swashplate 40 support surface. The hydrostatic support surface 51 is provided with a sealing portion for sealing the oil. The sealing portion is positioned around the inner and outer circumferences of the swashplate's oblong hole 53. The sealing portion includes an inner sealing portion 55 and an outer sealing portion 54 distributed radially inside and outside the swashplate's oblong hole 53, and a spacer sealing portion 56 distributed between adjacent swashplate oblong holes 53. The inner sealing portion 55 is the area enclosed by the inner edge of the swashplate's oblong hole 53 and the inner diameter R1 of the hydrostatic support surface 51. The outer sealing portion 54 is the area enclosed by the outer edge of the swashplate's oblong hole 53 and the outer diameter R2 of the hydrostatic support surface 51. The spacer sealing portion 56 is the spacer boss surface area between adjacent swashplate oblong holes 53. A certain reasonable gap is always maintained between the sealing portion of the hydrostatic support surface 51 and the swashplate 40 support surface to keep oil film leakage at a reasonable level. The hydrostatic support surface 51 of the slide 50 can be configured as a planar or spherical structure.

[0071] To reduce the bearing force on the slide plate support surface and reduce wear, multiple auxiliary support surfaces 57 can be added radially on the outer circumference of the slide plate 50, based on the slide plate waist-shaped hole 53 provided on the hydrostatic support surface 51. Figure 5 As shown, a radial oil drain groove 57b is provided between the auxiliary support surfaces 57, and an annular oil drain groove 57a is also provided between the auxiliary support surface 57 and the outer sealing part 54. The radial oil drain groove 57b and the annular oil drain groove 57a are interconnected.

[0072] like Figures 9-11As shown, the swashplate 40 has a swashplate support surface 41 that matches the hydrostatic support surface 51 of the swashplate. A low-pressure port 44 and a high-pressure port 45 are provided on the swashplate support surface 41. The low-pressure port 44 and the high-pressure port 45 are divided into two sides by the central axis of the swashplate. The low-pressure port 44 and the high-pressure port 45 can be configured as symmetrical or asymmetrical structures relative to the central axis. For example, the high-pressure port 45 can be configured as multiple waist-shaped windows with partitions 45b. This allows the swashplate to have a certain pre-pressure and pre-load. The pressure reduction function allows the swashplate low-pressure port 44 and high-pressure port 45 to rotate a certain angle along the central axis of the swashplate. Alternatively, a triangular groove 44a can be provided at the end of the low-pressure port 44 to transition from the low-pressure port 44 to the high-pressure port 45, and a triangular groove 45a or hole can be provided at the end of the high-pressure port 45 to transition from the high-pressure port 45 to the low-pressure port 44, serving as a pre-pressure reduction from high pressure to low pressure or a pre-pressure increase from low pressure to high pressure. In addition, the swashplate back side 42, opposite to the rear end cover 32, is provided with swashplate positioning holes 42a, bolt connection holes 42c, and fastener positioning holes 42d for installation and positioning.

[0073] Furthermore, the end face of the slide plate 50 facing the cylinder body has multiple plunger ball sockets 58 arranged circumferentially opposite to the plunger 70, such as... Figure 6 , Figure 7 As shown, the plunger ball socket 58 forms a roughly hemispherical recess on the end face of the slide plate 50. The plunger ball socket 58 supports the plunger in a manner that is evenly spaced around the common circumference of the slide plate axis 50C. After the plunger 70 is installed in the plunger ball socket 58, it is fixed to the end face of the slide plate 50 by a pressure plate 60, thereby restricting the movement of the plunger 70 away from the end face of the slide plate 50. In particular, the method of fixing the plunger 70 to the end face of the slide plate 50 is not limited to using a pressure plate. For example, a shape-locking clamping device can also be provided on the slide plate 50, which can fix the plunger ball head 71 by covering it with a greater than 180-degree angle.

[0074] The plunger 70 includes a plunger head 71 supported at one end on the plunger socket 58 of the slide plate 50 and fixed to the end face of the slide plate via a pressure plate 60; a plunger center hole 72 for connecting the plunger hole 81 and the plunger socket 58; a tapered rod portion 73 with a conical outer circumference; and a plunger portion 74 that is clearance-fitted with the cylinder plunger hole wall and can reciprocate therein. The plunger head 71 is spherical and can slide freely on the plunger socket 58 of the slide plate 50. The plunger center hole 72 is a large-diameter through-hole structure, serving as a channel for sucking in and / or discharging oil. At least one sealing ring is usually provided on the plunger portion 74 for sealing the liquid. The tapered rod portion 73 is a tapered shape that gradually increases from the plunger ball end to the plunger portion 74. When the plunger 70 moves to a certain position, the tapered rod portion 74 contacts the inner circumferential surface of the plunger hole 81, playing a force transmission role. However, it should be noted that the plunger 70 is not limited to the conical plunger type, but may also include a connecting rod plunger with ball heads at both ends or a spherical plunger with universal joints.

[0075] The distribution assembly includes a distribution plate 90 supported on the pump body 31 and a cylinder 80 supported on the distribution plate 90, such as Figure 8 As shown, the distribution plate structure of this embodiment is illustrated. The distribution plate 90 has a low-pressure distribution port 91 on the low-pressure side, and a triangular groove 93 or hole at the end of the low-pressure distribution port 91 transitioning from the high-pressure zone to the low-pressure zone. The high-pressure zone of the distribution plate does not have a distribution port, but is a closed planar structure. When the cylinder body waist-shaped hole 82 rotates to the low-pressure distribution port 91, it draws oil from the pump body cavity. When the cylinder body waist-shaped hole 82 rotates to the high-pressure zone, the cylinder body waist-shaped hole 82 is closed by the distribution plate, and the cylinder body 80 and the distribution plate 90 are supported by an oil film.

[0076] The cylinder body 80 has a cylindrical configuration with a circular radial cross section and is housed within the pump body cavity 35 of the pump body 31. The cylinder body 80 has a plurality of plunger holes 81 and plunger waist-shaped holes 82 evenly distributed around the cylinder body axis, and a rotation center hole 83 at the center for accommodating the main shaft. The number of plunger holes in the cylinder body 80 is generally set to 7 or 9. The drive shaft 10 passes through the rotation center hole 83 of the cylinder body 80 and is connected to the cylinder body 80 by a spline. The cylinder body 80 is cantilevered on the drive shaft 10 in a manner that it moves synchronously with the drive shaft 10.

[0077] It should be noted that the cylinder block 80 of this invention does not have bearings supporting it on its outer periphery. Instead, it is directly supported on the drive shaft extension end 10a. The main reason for this is that, due to the use of a conical plunger or connecting rod plunger structure, the lateral force of the plunger 70 is not transmitted to the cylinder block through the plunger. The drive shaft extension end primarily bears the centrifugal force of the plunger and cylinder block, which is far less than the lateral hydraulic pressure of the plunger. Therefore, the structure of this invention can significantly reduce the radial dimension of the plunger pump and avoid problems such as excessive noise, reduced reliability, and limited speed limits caused by large bearings on the outer periphery of the cylinder block.

[0078] In this embodiment, the plunger assembly is directly inserted into the shaft extension end of the motor assembly's drive shaft. The front end cover 16 of the motor assembly serves as the support for the plunger pump assembly. The oil inlet 33 is located on the pump body 31, and the oil outlet 32b is located on the rear end cover 32. This structure has the following advantages: First, it significantly increases the size of the oil inlet, improving the self-priming speed; second, it significantly reduces the axial dimension of the plunger pump assembly 3, especially further reducing the axial cantilever length of the drive shaft, thus significantly reducing the deflection deformation of the shaft extension end 10a of the drive shaft 10, thereby improving the compactness of the structure and the support strength of the drive shaft; third, it can utilize the bearings of the motor assembly itself, therefore the plunger pump assembly 3 does not need a separate bearing to support the drive shaft 10, further reducing costs.

[0079] To ensure that the distribution pair and sliding plate pair establish oil pressure when the plunger pump assembly starts to move, and to prevent pull-out force during oil suction during the movement, a certain preload and return force need to be applied to the distribution pair and sliding plate pair. This utility model achieves this function by setting an independent preload limit structure.

[0080] The independent preload limiting structure includes a preload structure near the cylinder 80 and a limiting structure near the swashplate 40. The preload structure and the limiting structure function independently. The preload structure generates a preload force by compressing the disc spring 15 through the preload bolt 13 connected to the main shaft 10, and transmits it to the cylinder 80, so that the cylinder 80 always abuts against the distributor plate 90. The limiting structure includes a fastener 46 fixed at the center of the swashplate 40, a limiting plate 47 that slides with the pressure plate 60, and a limiting clamping member 48 that presses the limiting plate 47 against the pressure plate 60. The limiting structure restricts the slide plate 50 from moving outward away from the swashplate 40 through the limiting plate 47.

[0081] Preferably, in this embodiment, the fastener 46 is a pin, and the fastener 46 is provided with a fastener bolt hole 46f and an internal hexagonal hole 46e for cooperating with the setting of the limiting clamping member 48.

[0082] In one preferred embodiment of the limiting structure, the locking member 46 and the swashplate 40 are separate structures. The locking member 46 is provided with a rotary fitting part 46a extending out of the swashplate 40, a locking member connecting part 46b connected to the center hole 41a of the swashplate, and a locking member positioning part 46c. The locking member 46 is connected to the center hole 41a of the swashplate by a threaded structure, or the locking member 46 can also be fixed to the swashplate 40 by an interference fit with the center hole 41a of the swashplate. The slide plate 50 is provided with a central through hole 52 in the middle. The slide plate is supported on the rotary fitting part 46a by a sliding bearing 52a in the central through hole 52 of the slide plate. In general, the sliding bearing 52a and the center through hole 52 of the slide plate are configured to be interference fit. In special cases, the slide plate can be directly supported on the rotary fitting part 46a without the sliding bearing. In addition, to ensure the accuracy of the connection between the fastener and the swashplate, a fastener positioning hole 42d is provided on the swashplate. When the fastener 46 is connected to the swashplate 40, the fastener positioning part 46c is inserted into the fastener positioning hole 42d.

[0083] To ensure that high-pressure oil leaking from the seal strip inside the slide plate can be quickly discharged through the gap between the slide plate and the swash plate, and to prevent high pressure accumulation from damaging the oil film, at least one oil drain groove 46d is provided on the rotating mating part 46a of the locking member 46. The oil drain groove 46d can be configured in a radial or spiral shape. In addition, an oil drain groove is also provided on the sliding bearing 52a. It is easy to understand that this structure, which provides an oil drain groove on the rotating mating part 46a and / or on the sliding bearing 52a, is also beneficial for lubricating the sliding bearing 52a and carrying away heat from the bearing, thus playing a role in active lubrication of the sliding bearing 52a and significantly improving the service life of the sliding bearing 52a.

[0084] To enhance the reliability of the contact between the sliding plate 50 and the swashplate 40, a limiting plate 47 is provided at the center of the pressure plate 60 and connected and fixed to the limiting clamping member 48 and the fastening member 46 to form a forced clearance limiting structure. The pressure plate 60 has a central support surface 61 that slides with the limiting plate 47. The limiting plate 47 and the pressure plate 60 form a friction pair. To provide better lubrication for this friction pair during sliding plate contact, multiple limiting plate oil drain grooves 47a and / or limiting plate oil drain holes 47b are provided on the outer periphery of the limiting plate 47 that contacts the central support surface 61. Simultaneously, oil leaking from the gap between the sliding plate and the swashplate is further discharged into the pump body cavity 35 through the limiting plate oil drain grooves 47a and / or the limiting plate oil drain holes 47b.

[0085] Another embodiment of the limiting structure, such as Figure 13As shown, the locking member 46 and the swashplate 40 are an integral structure. The rotating fitting part 46a of the locking member 46 is an outward extension of the center part of the swashplate. The slide plate 50 is supported on the rotating fitting part 46a by the sliding bearing 52a. At least one locking member oil drain groove 46d is provided on the rotating fitting part 46a for lubricating the sliding bearing 52a and leaking oil. The locking member oil drain groove 46d can be configured in a radial or spiral shape.

[0086] One preferred embodiment of the preload structure includes a preload bolt 13, a retaining ring 14, a disc spring 15, and a washer 16. A preload groove 84 for accommodating the preload structure is provided at the central end of the cylinder body 80. The preload bolt 13 is connected to the drive shaft 10 and compresses the disc spring 15. The first bearing 13 or the second bearing 14 is configured to withstand axial loads in the direction of the cylinder body 80 to ensure no axial movement. For example, it can be configured to include, but is not limited to, tapered roller bearings, deep groove ball thrust bearings, cylindrical roller bearings with flanges, and other bearing types.

[0087] The above structural analysis demonstrates that the independent preload limiting structure used in this embodiment replaces the multiple independent slippers and the structure utilizing the return plate in the prior art, offering the following significant advantages: The connection between the plunger and the slipper, and between the slipper and the pressure plate, is more reliable, avoiding wear and shearing damage at the slipper neck and shoulder, and cracking at the return plate drilling location, as seen in the prior art, thereby improving the operational reliability of the plunger pump assembly; Due to the use of the independent preload limiting structure, the rotational space of the slipper pair and the cylinder pair does not interfere with each other, thus significantly increasing the variable tilt angle, with the maximum tilt angle controlled between 21 and 40°, and preferably further controlled between 24° and... The angle is between 30° and 40°, which is much larger than the tilt angle of existing plunger pumps, thus significantly improving the displacement and power density of the plunger pump assembly. The preload can be set according to the different requirements between the sliding plate and swashplate, and between the cylinder block and the distributor plate (90°), solving the problem that traditional center spring return mechanisms can only set one preload. A limiting structure is set at the center of the pressure plate, resulting in a low contact linear velocity between the limiting plate and the pressure plate, and minimal wear on the limiting plate. Oil drain holes or grooves are provided on the rotary mating parts, limiting plate, and sliding bearings in the limiting structure, ensuring sufficient lubrication of the sliding bearings and locking components, as well as the sliding parts of the limiting plate and the pressure plate, preventing dry friction, adhesion, and burning.

[0088] The following is combined with Figure 4Further explanation of the double-end-face oil distribution structure adopted by the plunger pump assembly: A low-pressure oil inlet 33 is provided on the pump body 31, and a high-pressure oil outlet 32b is provided on the rear end cover 32. The low-pressure oil inlet 33 communicates with the pump body cavity 35. Simultaneously, an opening groove 43 facing the pump body cavity 35 is provided on the suction side of the swashplate 40, and the opening groove 43 communicates with the low-pressure port 44 of the swashplate. A third drain groove 42b is also provided on the swashplate 40, and the drain groove 42b communicates with the opening groove 43. The plunger 70 has a conical structure and is provided with a large-diameter plunger center hole 72 connecting the plunger ball socket 58 and the plunger bore 81. The sliding plate 50 is provided with a sliding plate waist-shaped hole 53 communicating with the plunger center hole 72. During oil suction, low-pressure oil enters from the inner cavity 4a of the oil tank through the low-pressure inlet 33, and then splits into two paths into the cylinder plunger bore 81. One path enters the cylinder plunger bore 81 through the pump body cavity 35 and the low-pressure port 92 of the distribution plate, while the other path enters the cylinder plunger bore 81 through the pump body cavity 35, the swashplate low-pressure port 44, the swashplate waist-shaped hole 53, and the plunger center hole 72. During oil discharge, high-pressure oil exits from the cylinder plunger bore 81 through the plunger center hole 72, the swashplate waist-shaped hole 53, the swashplate high-pressure port 45, and the high-pressure outlet 32b. The dual-end-face oil distribution structure allows hot oil leaking from the plunger pump assembly friction pair into the pump body cavity to directly enter the plunger bore and participate in the hydraulic system circulation, promptly carrying away heat. The oil in the pump body cavity 35 remains cold, resulting in minimal thermal deformation and minimal impact on the friction pair's performance. Furthermore, the elimination of the drain line simplifies the structure.

[0089] Example 2

[0090] like Figure 14 and Figure 15 As shown, another embodiment of the present invention is illustrated. The difference from embodiment 1 is that the limiting structure on one side of the swashplate is different. Other aspects can be referred to the structure described in embodiment 1.

[0091] The locking component 46 and the limiting plate 47 are connected and fixed into an integral structure. For example, the limiting plate 47 is an extension of the end of the locking component 46, or the limiting plate 47 is connected to the locking component 46 and the limiting plate 47 into a whole by welding, sintering, gluing, or other methods. From the front end to the rear end, the locking component is provided with the limiting plate 47, the rotary mating part 46a, the locking component positioning part 46c, and the locking component connecting part 46b in sequence. The advantage of this structure is that it eliminates the need for the limiting clamping component 48 and improves the reliability of the part's operation.

[0092] It can be predicted that the locking member 46 and the limiting plate 47 can be integrally formed from the same material, such as copper alloy. This will not only meet the end face matching requirements of the limiting plate 46 and the pressure plate 60 or the slide plate 50, but also meet the support requirements of the locking member 46 and the center hole of the slide plate. This will further eliminate the need for the sliding bearing 52a.

[0093] To achieve oil drainage, multiple oil drainage grooves 46d can be provided on the center hole 52 of the slide plate or on the support part 46a of the fastener 46, and a limit plate oil drainage groove can be provided circumferentially on the surface of the limit plate 47 that mates with the pressure plate.

[0094] Example 3

[0095] like Figure 16 As shown, another embodiment of the present invention is illustrated. The difference from embodiment 1 is that the locking structure on one side of the swashplate is different. Other aspects can be referred to the structure described in embodiment 1.

[0096] The fastening structure includes a fastening member 46, a fastening member bolt 46f, a fastening member disc spring 46g, and a fastening member limiting pin 46h. The fastening member 46 is provided with a rotating engagement part 46a and a fastening member positioning part 46c. A limiting plate 47 that engages with the pressure plate slide is provided between the fastening member 46 and the pressure plate 60. The fastening member 46 and the limiting plate 47 are either separate structures or connected and fixed into an integral structure. A fastening member disc spring 46g is provided between the fastening member bolt 46f and the limiting plate 47. A fastening member limiting pin 46h is provided between the fastening member positioning part 46c and the swashplate to limit the rotation of the fastening member. The fastening member bolt 46f passes through the fastening member and is fixedly connected to the swashplate.

[0097] When implemented according to the above embodiments, the following beneficial effects can be achieved:

[0098] (1) The power unit and electro-hydraulic actuator highly integrate components such as electric motor, hydraulic pump, oil tank, and cylinder assembly, eliminating couplings and oil pipelines. It features compact structure, light weight, small size, low power loss, and high power density, significantly reducing the space occupied by the actuator and the amount of hydraulic oil used. The overall structure has the advantages of compactness, modularity, and ultra-high power density, making it easy to install. It can fully utilize the high power-to-weight ratio of hydraulic power, making it particularly suitable for fields with strict requirements on space and weight. For example, it can be matched with distributed hydraulic actuator systems in the fields of engineering machinery, aerospace, and robotics, solving a series of problems such as long pipelines, large weight, and high energy consumption brought about by traditional centralized hydraulic actuator systems.

[0099] (2) The motor assembly and piston pump assembly in the power unit and electro-hydraulic actuator share the same drive shaft. The cylinder block of the piston pump assembly is supported on the drive shaft. The piston pump assembly can be designed as a modular assembly that can be directly inserted into the drive shaft, making installation convenient.

[0100] (3) The plunger assembly is directly inserted into the shaft extension end of the motor assembly drive shaft. The front end cover of the motor assembly serves as the support for the plunger pump assembly. The oil inlet is located on the pump body, and the oil outlet is located on the rear end cover. This structure has the following advantages: First, it can significantly increase the size of the oil inlet and improve the self-priming speed; second, it can significantly reduce the axial dimension of the plunger assembly, especially further reducing the axial cantilever length of the drive shaft, which significantly reduces the flexural deformation of the cantilever end of the drive shaft, thereby improving the compactness of the structure and the support strength of the drive shaft; third, it can also utilize the bearings of the motor assembly itself, so the plunger pump assembly does not need to have additional bearings to support the drive shaft, thereby further reducing costs.

[0101] (4) The power unit and electro-hydraulic actuator house components such as the plunger pump assembly in the oil tank. The plunger pump assembly is wrapped in oil and wetted by the oil through layers of nesting. The noise and vibration generated by the actuator are significantly reduced, making it particularly suitable for occasions with strict noise and vibration requirements.

[0102] (5) The power unit and electro-hydraulic actuator have good thermal stability, which is mainly reflected in: First, the plunger pump assembly is equipped with an oil suction port that opens into the inner cavity of the oil tank, and the oil inside the pump body can be circulated into the hydraulic system through double-end oil distribution to achieve oil self-cooling; Second, the electro-hydraulic assembly and the oil tank are isolated by a heat-insulating sealing strip to prevent the high temperature of the oil tank from affecting the electrical components in the motor assembly. Therefore, this power unit and electro-hydraulic actuator can operate continuously and at high power.

[0103] (6) The piston pump assembly in the power unit and electro-hydraulic actuator adopts an integral sliding plate structure and a conical piston structure. The unique design of the two significantly reduces the lateral force of the piston on the cylinder, significantly improves the working conditions of the three major friction pairs, and improves the stability of the oil film, so that the hydraulic pump assembly has higher speed and longer service life to match the working conditions of high-speed motor.

[0104] (7) The power unit and electro-hydraulic actuator rely on the unidirectional speed change of the motor assembly to achieve volume speed regulation and realize the reversing of the oil through the reversing valve. This structure can significantly reduce the overall cost on the one hand, and avoid motor damage caused by repeated high-frequency reversing under high-speed conditions with high rotational inertia on the other hand.

[0105] (8) The plunger pump assembly in the power unit and electro-hydraulic actuator adopts a high-pressure plunger pump structure, and the working pressure can reach more than 35MPa. Therefore, it can meet the requirements of engineering machinery and other fields that require long-term use under high pressure conditions.

[0106] The above description, in conjunction with specific preferred technical solutions, provides a further detailed explanation of this utility model. It should not be construed that the specific implementation of this utility model is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of this utility model. All technical solutions and improvements that do not depart from the spirit and scope of this utility model should be covered within the scope of the claims of this utility model.

Claims

1. A compact power unit, characterized in that, include: The motor assembly (1) is used to provide driving force and drive the plunger pump assembly (3) to operate; the front end of the drive shaft (10) of the motor assembly (1) extends from the front end cover of the motor and forms a shaft extension end; A plunger pump assembly (3) is used in conjunction with a motor assembly (1) to output hydraulic power. The plunger pump assembly (3) includes a pump body and is directly connected to the motor assembly. The plunger pump assembly (3) also includes a distribution pair and a sliding plate pair. Several plungers are provided in the pump body. One end of the plunger is connected to the cylinder body, and the other end of the plunger is connected to the swashplate through the sliding plate (50) and the pressure plate. The shaft extension end is directly inserted into the cylinder body in a cantilever state and supports the cylinder body. The shaft extension end works with the cylinder body to drive the plunger and the sliding plate (50) to rotate and realize the reciprocating motion of the plunger to perform oil suction and oil pressure. Low-pressure oil enters the plunger hole from the distribution pair and / or the sliding plate pair and discharges high-pressure oil from the sliding plate pair. The plunger pump assembly (3) is also connected to a control valve group to control the opening and closing of the pipeline for supplying hydraulic oil. The oil tank is used to contain hydraulic oil and supply oil to the piston pump assembly (3). The shaft extension end extends into the oil tank and the piston pump assembly (3) is located in the oil tank and submerged in hydraulic oil. The pump body is provided with an oil inlet that connects to the oil tank.

2. The compact power unit according to claim 1, characterized in that: The motor assembly (1) includes a motor housing, one end of which is closed by a front cover of the motor; the drive shaft (10) is located inside the motor housing and a rotor assembly is connected to the drive shaft (10); a stator assembly corresponding to the rotor assembly is provided on the inner surface of the motor housing; the front part of the drive shaft (10) is connected to the motor housing by a first bearing; and the rear part of the drive shaft (10) is connected to the motor housing by a second bearing.

3. The compact power unit according to claim 1 or 2, characterized in that: A heat-insulating sealing gasket (2) is provided between the motor assembly (1) and the oil tank and / or between the motor assembly (1) and the pump body. The heat-insulating sealing gasket (2) is used to prevent the temperature of the oil in the oil tank from being conducted to the inside of the motor assembly (1).

4. The compact power unit according to claim 1 or 2, characterized in that: An oil seal assembly is provided between the drive shaft (10) and the front end cover of the motor, and the opening of the oil seal assembly faces the plunger pump assembly (3).

5. The compact power unit according to claim 1, characterized in that: The cylinder body is provided with plunger holes corresponding to the plungers. The plungers enter the plunger holes from the rear end face of the cylinder body and slide back and forth relative to the plunger holes. The plunger holes extend through to the front end face of the cylinder body and are covered by the distribution plate on the front end face of the cylinder body. The distribution plate is provided with a low-pressure distribution port (92). The cylinder body rotates relative to the distribution plate and sucks oil when the plunger holes are connected to the low-pressure distribution port (92).

6. The compact power unit according to claim 5, characterized in that: The front end face of the slide (50) is provided with a plunger ball socket corresponding to the plunger. The plunger ball socket passes through the waist-shaped hole of the slide (50) to the rear end face of the slide (50). The rear end face of the slide (50) is also provided with a sealing structure and an oil draining structure. The pressure plate is set in close contact with the slide (50) and is provided with a pressure plate hole corresponding to the plunger ball socket. The pressure plate hole cooperates with the plunger so that the end of the plunger is always located in the plunger ball socket.

7. The compact power unit according to claim 6, characterized in that: The swash plate is provided with an inclined surface for the slide plate (50) to be placed at an angle. The swash plate is provided with a low-pressure port and a high-pressure port that are connected to the inclined surface. The low-pressure port is connected to the pump body cavity and is submerged in hydraulic oil. The high-pressure port is connected to the oil outlet on the rear end cover of the pump body. When the slide plate (50) rotates to the plunger waist-shaped hole connected to the low-pressure port of the swash plate, it draws in oil. When the slide plate (50) rotates to the plunger waist-shaped hole connected to the high-pressure port of the swash plate, it pressurizes oil.

8. The compact power unit according to any one of claims 1, 5 to 7, characterized in that: The pressure plate and slide plate (50) are connected and cooperate with the swashplate through a fastening structure. The fastening structure includes a fastening member connected to the swashplate. The fastening member includes a fastening member positioning part aligned with the swashplate, a fastening member connecting part connected and fixed to the swashplate, and a rotary cooperation part connected and cooperated with the pressure plate and slide plate (50). The fastening member keeps the pressure plate and slide plate (50) in close contact through a limiting structure. The limiting structure is installed to the fastening member through a connecting member or the limiting structure is integrally formed with the fastening member.

9. The compact power unit according to any one of claims 1, 5 to 7, characterized in that: The pressure plate and the slide plate (50) are connected and fitted to the swashplate through a locking structure. The locking structure includes a rotary fitting part that protrudes from the surface of the swashplate and forms a cylindrical protrusion. The pressure plate and the slide plate (50) are both connected and fitted to the rotary fitting part and rotate along the rotary fitting part. The top of the rotary fitting part is kept in close contact with the pressure plate and the slide plate (50) by a limiting structure. The limiting structure is installed to the rotary fitting part by a connector.

10. The compact power unit according to any one of claims 1, 5 to 7, characterized in that: The pressure plate and slide plate (50) are connected and cooperate with the swashplate through a fastening structure. The fastening structure includes a fastening element, a fastening element bolt, a fastening element disc spring, and a fastening element limiting pin. The fastening element is provided with a rotating engagement part and a fastening element positioning part. A limiting plate that cooperates with the pressure plate and slide plate is provided between the fastening element and the pressure plate. The fastening element and the limiting plate are either separate structures or connected and fixed into an integral structure. A fastening element disc spring is provided between the fastening element bolt and the limiting plate. A fastening element limiting pin is provided between the fastening element positioning part and the swashplate to limit the rotation of the fastening element. The fastening element bolt passes through the fastening element and is fixedly connected to the swashplate.

11. The compact power unit according to claim 1, characterized in that: The cylinder body is provided with a rotation center hole for connecting the shaft extension end. The shaft extension end passes through the rotation center hole and is provided with a fastener and a blocking plate at its end. An elastic preload is provided between the blocking plate and the rotation center hole, and the elastic preload applies an elastic preload force to the cylinder body.

12. An electro-hydraulic actuator comprising the compact power unit according to any one of claims 1 to 11, characterized in that: The oil outlet structure of the compact power unit is connected to the oil distribution pipeline, which is connected to the hydraulic cylinder assembly (6) used to drive the load. The hydraulic cylinder assembly (6) includes a cylinder (6a), a piston rod (6b) is provided inside the cylinder (6a), and the piston rod (6b) divides the cylinder (6a) into two action chambers. Both action chambers are provided with oil ports. The oil distribution pipeline is connected to the oil ports of the two action chambers respectively and the oil inlet is controlled by the control valve (5). The front end of the piston rod (6b) is provided with a drive connection structure and is used to connect and drive the load. The hydraulic cylinder assembly (6) includes an asymmetrical single rod or a symmetrical double rod structure.

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