Axial integrated compact power unit and electro-hydraulic actuator

Abstract

The utility model discloses an axial integrated compact type power unit and electro-hydraulic actuator, including motor subassembly, plunger pump subassembly, junction valve block, oil tank, the junction valve block is provided between motor subassembly and plunger pump subassembly, the one end of junction valve block seals motor subassembly shell, the other end seals plunger pump subassembly shell and oil tank, the junction valve block is equipped with the oil tank. The connecting valve block is provided with a bearing for supporting the front end of a rotating shaft and a shaft seal for sealing oil, the rotating shaft of the motor assembly penetrates through the connecting valve block and extends out to form a shaft extension end, the shaft extension end is directly inserted into a center hole of the cylinder body, the shaft extension end of the rotating shaft supports the cylinder body in a cantilever mode and drives the cylinder body to synchronously run through a key, and the cylinder body abuts against the valve plate under the action of hydraulic force. The valve plate is supported on the connecting valve block, and the connecting valve block is provided with a flow distribution window, an oil channel and a control valve set and conveys and receives oil outwards. 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 an axially integrated 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 oil supply pressure drive pipeline, large oil consumption, and requires 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 connected together in series and parallel. The integration is not high, each component occupies a large volume space and is heavy, and the overall power-weight ratio is relatively low.

[0009] (2) Most of the hydraulic pumps used in the existing electro-hydraulic actuator (EHA) power units are gear pumps, which generally operate at medium pressure or below. At the same time, gear pumps have poor low-speed performance and high noise, making it difficult to meet the requirements of good electro-hydraulic performance matching, high-pressure conditions and low noise under the trend of electrification.

[0010] (3) 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.

[0011] It is evident that current electro-hydraulic power units and electro-hydraulic actuators still have room for improvement and should be optimized to overcome the shortcomings of existing technologies. Utility Model Content

[0012] This utility model discloses an axially integrated compact power unit and an electro-hydraulic actuator. The purpose is to provide a new type of power unit and electro-hydraulic actuator with a highly compact structure, small size, light weight, low noise, high efficiency and energy saving, and high power density, 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 axially integrated compact power unit solution adopted in this utility model is as follows:

[0014] An axially integrated compact power unit includes:

[0015] The motor assembly is connected in conjunction with the plunger pump assembly to provide electric drive or to generate electricity; the front end of the motor assembly's shaft is supported on the connecting valve block and extends through the connecting valve block to form a shaft extension end;

[0016] A plunger pump assembly includes a pump housing, within which a flow distribution pair, a plunger pair, and a sliding plate pair are disposed. The pump housing and flow distribution pair of the plunger pump assembly are connected to a connecting valve block. The plunger pair includes a cylinder body and a plurality of plungers. One end of the plunger engages with the cylinder body, and the other end of the plunger engages with the sliding plate pair. The shaft extension end is connected to and supports the cylinder body in a cantilevered state. The shaft extension end, in conjunction with the cylinder body, drives the plunger to rotate, thereby realizing the reciprocating motion of the plunger for oil suction and oil pressure.

[0017] A connecting valve block is disposed between the motor assembly and the plunger pump assembly. One side of the connecting valve block encloses the housing of the motor assembly, and the other side encloses the pump housing and oil tank of the plunger pump assembly. The connecting valve block is provided with a flow distribution window, an oil passage, and a control valve group for external delivery and reception of oil. The flow distribution window and oil passage are connected to the flow distribution pair of the plunger pump assembly.

[0018] An oil tank is used to contain hydraulic oil and a plunger pump assembly. The shaft extension end extends into the oil tank and the plunger pump assembly is located in the oil tank and submerged in hydraulic oil. The pump housing is provided with an oil port that connects to the oil tank.

[0019] The aforementioned compact power unit connects the motor assembly and the plunger pump assembly into one unit via a connecting valve block. After connection, the motor assembly and the plunger pump assembly rotate synchronously. This allows the motor assembly to drive the plunger pump assembly to operate, thereby driving an electro-hydraulic actuator to operate and drive a load, or the plunger pump to drive the motor to generate electricity. The power unit in this invention reduces some connecting pipe support structures, resulting in a more streamlined and compact overall structure with better stability and reliability. Furthermore, the motor assembly can operate in both power generation and driving modes, and the plunger pump assembly can switch between pump and motor modes.

[0020] Furthermore, in this invention, the generator assembly can have various structural 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 motor end cover; the other end of the motor housing is closed by a valve block; the rotating shaft extends from inside the motor housing to the outside and a rotor assembly is connected to the rotating shaft; a stator assembly corresponding to the rotor assembly is provided on the inner surface of the motor housing; the rear part of the rotating shaft is connected to the motor housing via a second bearing, and the front part of the rotating shaft is connected to the connecting valve block via a first bearing. With this design, the motor housing and the connecting valve block form a closed motor cavity, and the rotating shaft, stator assembly, and rotor assembly are all housed within this cavity. By incorporating the connecting valve block as part of the motor assembly, the structure of the motor assembly can be simplified, thereby reducing the overall size of the power unit.

[0021] Furthermore, the rotating shaft, after mating with the connecting valve block, extends into the oil tank to mate with the plunger pump assembly, thereby achieving synchronous rotation. To prevent hydraulic oil from entering the motor assembly, an oil seal should be applied to the mating area between the rotating shaft and the connecting valve block. Various methods can be used, and there is no single limitation. Here, we optimize and propose one feasible option: an oil seal assembly is installed between the rotating shaft and the connecting valve block to prevent hydraulic oil from entering the motor assembly. When using this solution, the oil seal assembly can be a skeleton oil seal, with the opening of the skeleton oil seal facing the plunger pump assembly.

[0022] Furthermore, in this invention, to make the fit between the rotating shaft and the connecting valve block more stable and reliable, an optimization is proposed, and one feasible option is suggested: a third bearing is provided between the rotating shaft and the connecting valve block. With this solution, the third bearing can be located in the middle of the shaft hole on the connecting valve block, and a sliding bearing with a smaller radial thickness can be used, allowing for self-lubrication using hydraulic oil from the oil tank side.

[0023] Furthermore, the structure of the connecting valve block can be constructed in various forms and is not limited to a single one. Here, we optimize and propose one feasible option: the connecting valve block is provided with a connecting boss. The flow distribution pair of the plunger pump assembly abuts against the end face of the connecting boss. The flow distribution plate surface of the flow distribution pair is attached to the end face of the connecting boss and communicates with the flow distribution window of the connecting boss. The front end of the pump housing of the plunger pump assembly forms an opening that fits and is fixed to the side surface of the connecting boss. With this design, the connection between the connecting valve block and the plunger pump assembly is tighter, resulting in a better sealing effect.

[0024] Furthermore, in this invention, the structure of the sliding plate pair can be constructed in various forms and is not limited to a single one. Here, we optimize and propose one feasible option: the sliding plate pair includes a swashplate and a sliding plate supported on the swashplate. The plunger is connected to the sliding plate via a pressure plate. The front end face of the sliding plate is provided with plunger ball sockets corresponding to the plungers. The plunger ball sockets extend to the rear end face of the sliding plate through a central oil hole and a waist-shaped hole in the sliding plate. The rear end face of the sliding plate is also provided with a sealing structure and an oil draining structure. The pressure plate is set against the front end face of the sliding plate and has 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. When this scheme is adopted, the sliding plate pair cooperates with the plunger pair and is always in cooperation with the end of the plunger, thereby realizing the extension and retraction of the plunger during rotation, thus realizing the oil suction and oil pressure of the plunger pair.

[0025] Furthermore, the pressure plate in the swashplate pair must cooperate with the swashplate to connect the plunger and maintain stable operation. The specific connection method can take several forms and is not limited to one. Here, we optimize and propose one feasible option: the pressure plate and swashplate are connected to the swashplate via a locking structure. The locking structure includes a locking element, which has a limiting plate portion, a rotating engagement portion, a locking element positioning portion, and a locking element connecting portion. The limiting plate portion cooperates with the pressure plate to keep the swashplate and swashplate in close contact. The swashplate is swivelly supported on the rotating engagement portion. The locking element positioning portion is inserted into the swashplate's central positioning hole. The locking element connecting portion connects to the swashplate's central connecting hole. A locking element limiting end face is provided between the rotating engagement portion and the locking element positioning portion, and the locking element limiting end face abuts against the swashplate support surface. With this scheme, the swashplate's central positioning hole and central connecting hole are coaxially arranged and connected to the locking element via threads.

[0026] Furthermore, the locking structure can also be connected in other ways. Here, we optimize and propose one feasible option: the pressure plate and the sliding plate are connected to the swashplate through the locking structure. The locking structure includes a locking element, a locking element bolt, a locking element disc spring, and a locking element limiting pin. The locking element includes a limiting plate part, a rotating fitting part, and a locking element positioning part. The locking element disc spring is disposed between the locking element bolt and the limiting plate. The locking element limiting pin is disposed between the locking element positioning part and the swashplate and is used to keep the locking element circumferentially fixed. The locking element bolt passes through the locking element and is fixedly connected to the swashplate. When using this method, the connection method using locking bolts is more convenient for disassembly and assembly operations. Moreover, the separate locking element bolt and locking element simplify the structure of the locking element, which can reduce the production and processing costs of the locking element and facilitate the reduction of maintenance costs.

[0027] Furthermore, to maintain a tight fit between the plunger assembly, the flow distribution assembly, and the connecting valve block, various fit structures can be adopted, and there is no single limitation. Here, we optimize and propose one feasible option: 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 cylinder body. The elastic preload applies an elastic preload force to the cylinder body, causing the cylinder body and the flow distribution assembly to press against the connecting valve block. With this scheme, the elastic preload can be a spring, with one end applying an elastic force to the cylinder body to press against it, and the other end pressing against the fastener and blocking plate on the shaft extension end, thereby maintaining a tight fit between the cylinder body, the sliding plate assembly, and the connecting valve block, while simultaneously satisfying oil suction and pressure during rotation.

[0028] The above describes the power unit. This utility model also discloses an electro-hydraulic actuator, which will be described below.

[0029] An electro-hydraulic actuator includes the aforementioned axially integrated compact power unit, comprising a hydraulic cylinder assembly that is connected to and cooperates with the power unit. The hydraulic cylinder assembly includes a cylinder barrel and a piston rod that cooperate with each other. One end of the cylinder barrel is provided with a connecting block and connected to a connecting valve block. The piston rod divides the cylinder barrel into two actuating chambers at intervals. Both actuating chambers are provided with oil ports. The oil passage of the connecting valve block extends to the connecting block and is respectively connected to the oil ports of the two actuating chambers.

[0030] The aforementioned electro-hydraulic actuator uses hydraulic oil supplied by a power unit as the driving medium, enabling the hydraulic cylinder assembly to reciprocate and drive the load. Simultaneously, by configuring the plunger pump assembly as a closed structure, the hydraulic cylinder assembly's movement sends hydraulic oil into the plunger pump assembly, thereby rotating the cylinder and ultimately driving the motor assembly to generate electricity. This dual-acting electro-hydraulic actuator is more convenient and flexible to use, and offers richer functionality.

[0031] Furthermore, in this invention, the operating mode of the motor assembly can be diversified, and the type of motor used is not limited to a single one. Here, we propose an optimized and feasible option: the motor assembly uses a servo motor, which is connected in conjunction with a driver and controller. The servo motor works with the driver and controller to perform variable-speed volume control on the plunger pump assembly to adjust the flow rate of the output oil. With this approach, the servo motor's operating mode becomes more flexible and diverse.

[0032] Furthermore, in this invention, the motor assembly can be further optimized. One feasible option is as follows: the motor assembly employs a servo motor with dual functions of power generation and drive, and the plunger pump assembly employs a bidirectional four-quadrant plunger pump. The plunger pump assembly operates in either pump mode or motor mode. When the plunger pump assembly operates in pump mode, the servo motor assembly operates in drive mode; when the plunger pump assembly operates in motor mode, the servo motor assembly operates in power generation mode. With this scheme, the motor can rotate forward to drive the plunger pump assembly and hydraulic cylinder assembly, thus driving the load; alternatively, the reverse thrust of the hydraulic cylinder assembly can achieve reverse rotation, thereby generating electricity.

[0033] This utility model also discloses various application methods of electro-hydraulic actuators, which are described below.

[0034] An application of an electro-hydraulic actuator, using the electro-hydraulic actuator described above, wherein the power unit constitutes a bidirectional closed system, and the motor assembly and the plunger pump assembly cooperate to operate in both directions. High-pressure oil is output from the plunger pump assembly, transported to the actuator via the connecting valve block, and then returned to the plunger pump assembly via the connecting valve block. The connecting valve block is equipped with a control valve group, which includes at least two relief valves connected to the main oil circuit, two pressure sensors, two replenishing check valves, and one electromagnetic unloading valve.

[0035] In the aforementioned application of electro-hydraulic actuators, the bidirectional closed system of the power unit refers to the plunger pair drawing oil from only one side of the distribution pair and simultaneously pressurizing oil from the same side, while the sliding plate pair remains sealed. This type of electro-hydraulic actuator allows for switching between forward and reverse rotation, enabling different operating modes.

[0036] An application of an electro-hydraulic actuator, using the electro-hydraulic actuator described above, wherein the power unit constitutes a one-way open system, the motor assembly operates in one direction and drives the plunger pump assembly to operate, the plunger pump assembly draws oil from the oil tank and delivers it to the actuator via the connecting valve block, and after the actuator acts, the oil returns to the oil tank via the connecting valve block; the connecting valve block is provided with a control valve group, the control valve group including at least one relief valve, one directional valve or one directional throttle valve.

[0037] The aforementioned application of electro-hydraulic actuators, specifically the unidirectional open power unit system, refers to a piston assembly that can draw oil from both sides of the distribution pair and the sliding plate pair, while simultaneously pressurizing oil from one side of the distribution pair. Electro-hydraulic actuators with this structure can only rotate in either the forward or reverse direction, and the operating mode of the motor and piston pump assembly is singular and cannot be switched.

[0038] Compared with the prior art, some of the beneficial effects that this utility model can achieve include:

[0039] The power unit disclosed in this utility model outputs power by driving a plunger pump assembly with a motor. It has a compact structure, significantly reduced structural parts, and significantly reduced axial dimensions. The plunger pump assembly has good high and low speed performance, good matching between the plunger pump assembly and the motor, stable overall operation, higher power density, and can ensure the reliability of output, thereby reducing the overall cost. Attached Figure Description

[0040] Figure 1 This invention relates to a bidirectional closed-type axial integrated compact electro-hydraulic actuator.

[0041] Figure 2 This is a schematic diagram illustrating the working principle of the bidirectional closed-type axial integrated compact electro-hydraulic actuator of this utility model.

[0042] Figure 3 This is a schematic diagram showing the four working states of an electro-hydraulic actuator.

[0043] Figure 4 for Figure 1 The bidirectional closed-axis integrated compact power unit.

[0044] Figure 5 This is a structural diagram of the plunger pump assembly in this utility model.

[0045] Figure 6 for Figure 5 AA section view.

[0046] Figure 7 This is a schematic diagram of the end face structure of the slide plate in this utility model.

[0047] Figure 8 In this utility model Figure 7 CC cross-section view.

[0048] Figure 9 This is a schematic diagram of the other end face of the slide plate in this utility model.

[0049] Figure 10 This is a schematic diagram of the distribution plate in this utility model.

[0050] Figure 11 This is a schematic diagram of the swashplate support surface in this utility model.

[0051] Figure 12 In this utility model Figure 11 DD cross-sectional view.

[0052] Figure 13 This is a schematic diagram of another structure of the swashplate support surface in this utility model.

[0053] Figure 14 This is a cross-sectional view of the fastener in this utility model.

[0054] Figure 15 In this utility model Figure 14 Axonometric view of the fastener.

[0055] Figure 16 This is a structural diagram of a piston pump assembly with another fixed structure in this utility model.

[0056] Figure 17 This is a structural diagram of the connecting valve block in this utility model.

[0057] Figure 18 In this utility model Figure 17 AA cross-section view.

[0058] Figure 19 In this utility model Figure 17 BB cross-section.

[0059] Figure 20 This is a unidirectional open axial integrated compact power unit in this utility model.

[0060] Figure 21 In this utility model Figure 20 A schematic diagram illustrating the working principle of the embodiment.

[0061] Figure 22 In this utility model Figure 20 Structural diagram of the plunger pump assembly in the embodiment

[0062] Figure 23 In this utility model Figure 20 Slide structure diagram of the embodiment

[0063] Figure 24 In this utility model Figure 20 Connection valve block structure diagram of the embodiment

[0064] Marked in the image:

[0065] 1. Motor assembly; 2. Controller; 3. Connecting valve block; 4. Piston pump assembly; 5. Oil tank; 5a. Oil tank inner cavity; 6. Hydraulic cylinder assembly; 6a. Cylinder barrel; 6b. Piston rod; 6c. Guide seat; 6d. Piston; 6e. Connecting block; 6g. Cylinder barrel first cavity; 6h. Cylinder barrel second cavity; 10. Shaft; 10a. Shaft extension end; 11. Motor stator assembly; 12. Motor rotor assembly; 13. First bearing; 14. Second bearing; 15. Motor housing; 16. Skeleton oil seal; 17. Third bearing; 18. Encoder; 20. Fastener; 21. Blocking plate; 22. Elastic preload; 23. Set bolt ; 24. Locking disc spring; 25. Locking limit pin; 31. Pump housing; 32. Oil port; 33. Rear end cover; 33a. Rear end cover oil inlet; 34. Connecting bolt; 35. Pump housing cavity; 36. Housing positioning part; 40. Swashplate; 41. Swashplate support surface; 42. Swashplate first waist-shaped groove; 43. Swashplate second waist-shaped groove; 44. Swashplate center positioning hole; 45. Swashplate center connecting hole; 46. Swashplate bolt connecting hole; 50. Sliding plate; 51. Sliding plate hydrostatic support surface; 52. Sliding plate center hole; 52a. Sliding bearing; 53. Sliding plate waist-shaped hole; 53a. Sliding plate oil hole; 54. Sliding plate outer sealing part; 5 5. Sliding disc inner sealing part; 56. Sliding disc interval sealing part; 57. Sliding disc auxiliary support surface; 57a. Sliding disc annular oil drain groove; 57b. Sliding disc radial oil drain groove; 58. Plunger ball socket; 60. Pressure plate; 70. Plunger; 71. Plunger ball head; 72. Plunger center hole; 73. Tapered rod part; 74. Plunger part; 80. Cylinder body; 81. Plunger hole; 82. Cylinder body waist-shaped hole; 84. Preload groove; 90. Distribution plate; 91. Static pressure support surface; 92. First distribution port; 93. Second distribution port; 94. Triangular groove; 100. Fastening element; 101. Limiting plate part; 102. Limiting plate oil drain groove; 103. Rotary distribution plate 104. Rotary part oil drain groove; 105. Fastener limiting end face; 106. Fastener positioning part; 107. Fastener connecting part; 108. Internal hexagonal hole; 110. First overflow valve; 111. Second overflow valve; 112. Pressure sensor; 113. Electromagnetic unloading valve; 301. Connecting boss; 302. Valve block support surface; 303. Valve block first distribution port; 304. Valve block second distribution port; 305. Oil drain groove; 306. First bearing support part; 307. Shaft seal sealing part; 308. Third bearing support part; 309. Valve block first oil port; 310. Valve block second oil port; 311. Support rib. Detailed Implementation

[0066] The present invention will now be described in detail with reference to the accompanying drawings.

[0067] 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.

[0068] For ease of description, embodiments of the present invention are shown in a typical orientation such that when the central axis of the rotating 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.

[0069] Example 1

[0070] like Figures 4 to 19 The diagram illustrates the axially integrated compact power unit of this invention. This power unit is a bidirectional closed-loop power unit, comprising a motor assembly 1, a connecting valve block 3, a plunger pump assembly 4, and an oil tank 5. The motor assembly 1, connecting valve block 3, and plunger pump assembly 4 are arranged axially from left to right. The connecting valve block 3 is positioned between the motor assembly and the plunger pump assembly, with one end sealing the motor assembly housing and the other end sealing the plunger pump assembly housing and the oil tank. The front end of the motor assembly's shaft is supported on the connecting valve block and extends through it to form a shaft extension. This shaft extension is directly inserted into the rotation center hole. The shaft extension cantilever supports the cylinder body and drives the cylinder body to rotate synchronously via a key. Under hydraulic pressure, the cylinder body abuts against a distribution plate, which is supported by the connecting valve block. The connecting valve block is equipped with a distribution window, oil passage, and control valve assembly for external oil delivery and reception. The motor assembly and piston pump assembly are bidirectional motion, and the power unit hydraulic system is a closed system, that is, the motor assembly and piston pump assembly can operate in both directions. The high-pressure oil in the main oil circuit of the hydraulic system is output from the piston pump assembly and returned to the piston pump assembly through the return oil line after the actuator is activated.

[0071] like Figure 1 As shown, this utility model includes Figure 4An axially integrated compact electro-hydraulic actuator. This actuator also includes a hydraulic cylinder assembly 6, which comprises a cylinder 6a, a piston rod 6b, a guide seat 6c, a piston 6d, and a connecting block 6e. The piston 6d divides the cylinder 6a into a first chamber 6g and a second chamber 6h. The connecting block 6e is fixedly connected to the cylinder 6a. A plunger pump assembly 3 is housed within an oil tank cavity 5a. The motor assembly 3 and the plunger pump assembly 4 share a rotating shaft 10. The high-pressure oil output from the plunger pump assembly 3 is delivered to either the first chamber 6g or the second chamber 6h via a connecting valve block 3 and a control valve, thereby enabling the extension and retraction of the piston rod 6b.

[0072] like Figure 2 This is a schematic diagram illustrating the working principle of the electro-hydraulic actuator of this utility model. Motor assembly 1 is a bidirectional servo motor assembly. Under the action of the driver and controller, the servo motor assembly achieves variable speed and volume control of the plunger pump assembly, and outputs oil at different required flow rates. The controller compares the real-time displacement feedback from the hydraulic cylinder and the pressure signals from the two chambers of the hydraulic cylinder with the given command, and outputs a control signal to adjust the speed and direction of the servo motor. The servo motor directly drives the bidirectional plunger pump assembly. Different servo motor speeds result in different hydraulic pump outlet flow rates, achieving speed regulation control; different servo motor rotation directions result in different hydraulic pump output flow directions, achieving reversing control.

[0073] The connecting valve block 3 is equipped with a control valve assembly for safety and oil replenishment. This control valve assembly serves only as an auxiliary component of the system. The control valve assembly includes at least two relief valves (first relief valve 110 and second relief valve 111) connected to the main oil pipeline, two pressure sensors 112, two oil replenishment check valves, and one electromagnetic unloading valve 113. The control valve assembly can also be supplemented with a balance valve or a hydraulically controlled check valve as needed. If necessary, an accumulator can also be installed on the connecting valve block to achieve oil replenishment and energy storage.

[0074] In a specific application, such as applications requiring urgent energy recovery, such as medium and large forklifts and lifting trucks, the servo motor assembly is configured as a servo motor with dual functions of power generation and drive. When the servo motor assembly is configured as a servo motor assembly with dual functions of power generation and drive, the matching plunger pump assembly is a bidirectional four-quadrant plunger pump assembly. The plunger pump assembly operates in pump mode or motor mode. When the plunger pump assembly operates in pump mode, the motor assembly operates in drive mode. When the plunger pump assembly operates in motor mode, the motor assembly operates in power generation mode.

[0075] like Figure 3As shown, taking a single-rod double-acting hydraulic actuator as an example, the direction of the hydraulic cylinder extension is defined as the positive direction of velocity, and the direction of the force opposing the extension of the hydraulic cylinder is taken as the positive direction. Based on the direction of the external load force and velocity, the operating conditions of the electro-hydraulic actuator are divided into four types: In the first quadrant, the load force performs negative work, the rodless chamber is a high-pressure controllable chamber with a large flow demand, and the accumulator compensates for the asymmetrical flow to the system through a hydraulically controlled check valve. At this time, the piston pump assembly operates in pump mode, and the servo motor operates in drive mode. In the second quadrant, the load force performs positive work, the rod chamber is a high-pressure controllable chamber, and the accumulator compensates for the asymmetrical flow to the system through a hydraulically controlled check valve. At this time, the piston pump assembly operates in motor mode, and the servo motor operates in generator mode. In the third quadrant, the load force performs negative work, the rod chamber is a high-pressure controllable chamber, the hydraulically controlled check valve opens under the action of high-pressure oil in the rod chamber, and the system charges the accumulator. At this time, the piston pump assembly operates in pump mode, and the servo motor operates in drive mode. In the fourth quadrant, the load force does positive work, the rodless chamber is a high-pressure controllable chamber, the hydraulic check valve opens under the action of high-pressure oil in the rod chamber, and the system charges the accumulator with oil. At this time, the plunger pump assembly operates in motor mode, and the servo motor operates in generator mode.

[0076] From the above structure, it can be seen that by relying on different working condition combinations of the dual-function servo motor assembly and the four-quadrant piston pump assembly, the following can be achieved: (1) variable speed volume speed regulation; (2) reversing; and (3) energy recovery. Therefore, this structure and system are particularly suitable for fields such as electric medium and large forklifts and electric lifting trucks that require energy recovery and energy saving, which can significantly reduce the overall cost and extend the battery life of the equipment.

[0077] It should be noted that (1) this embodiment shows an asymmetrical single-rod hydraulic cylinder, and it can be predicted that this utility model is also applicable to symmetrical double-rod hydraulic cylinders; (2) the four working conditions described in this utility model are not required for all machines and equipment that require energy recovery, but are determined according to the specific working conditions. For example, forklifts that only lift up and down only need to use the first and fourth quadrants.

[0078] The core component of a compact electro-hydraulic actuator is the power unit, which determines the actuator's performance. Figure 4As shown, this utility model's axially integrated compact power unit includes a motor assembly 1, a connecting valve block 3, a plunger pump assembly 4, and an oil tank 5. The motor assembly 1 includes a rotating shaft 10, a stator assembly 11, a rotor assembly 12, and a motor housing 15. The plunger pump assembly 4 is completely housed inside the oil tank 5. The plunger pump assembly 4 includes a pump housing 31, a distribution plate 90, a cylinder 80, and a swashplate 40. The shaft extension end 10a of the rotating shaft 10 is directly inserted into the rotation center hole. The shaft extension end 10a of the rotating shaft 10 cantilever supports the cylinder 80 and drives the cylinder to rotate synchronously via a key. The cylinder 80 abuts against the distribution plate 90 under hydraulic pressure. The distribution plate 90 is supported on the connecting valve block. The pump housing 31 is provided with an oil port 32 that opens into the inner cavity 5a of the oil tank, so that the pump housing cavity 35 communicates with the inner cavity 5a of the oil tank.

[0079] A skeleton oil seal 16 is provided between the rotating shaft 10 and the connecting valve block, and the opening of the skeleton oil seal 16 faces the plunger pump assembly 3.

[0080] Furthermore, in order to reduce the length of the cantilever of the rotating shaft 10 and to prevent excessive oil leakage from the oil tank side into the motor housing cavity when the skeleton oil seal 16 fails, a third bearing 17 is also provided between the rotating shaft 10 and the connecting valve block. The third bearing 17 is preferably a sliding bearing.

[0081] The motor assembly 1 includes a stator assembly 11 and a rotor assembly 12. A certain air gap is maintained between the stator assembly 11 and the rotor assembly 12 to ensure that the motor has a reasonable power factor and starting performance during operation. The rotor assembly 12 is fixedly connected to the 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 force applied by the plunger pump assembly 3 at the 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 adopts a permanent magnet synchronous motor, and the rotor assembly 12 of the motor assembly includes at least permanent magnets 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 2. The other end of the rotor shaft is connected to an encoder 18, and the encoder 18 signal is transmitted to the controller 2 through a data line.

[0082] like Figure 5 As shown, the plunger pump assembly 3 is a sliding disc type non-through shaft structure, including a pump housing 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 33. The axis of the rotating shaft 10 coincides with the axis of the cylinder 80. The shaft extension end 10a of the rotating shaft 10 extends out of the motor housing 15 and passes through the connecting valve block 3. The shaft extension end 10a of the rotating shaft 10 cantilever supports the cylinder 80 and is connected to the cylinder 80 through a main shaft spline. The shaft extension end 10a of the rotating 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.

[0083] The pump housing 31 is fixedly connected to the rear end cover 33 by bolts. The pump housing 31 is also provided with an oil port 32, which opens into the inner cavity 5a of the oil tank. The pump housing 31 has a pump housing cavity 35, which is connected to the inner cavity 5a of the oil tank through the oil port 32.

[0084] 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 through a sliding plate oil hole 53a. Preferably, the number of sliding plate waist-shaped holes 53 and plunger ball sockets 58 is set to 7 or 9. Figure 7 , Figure 8 , Figure 9 As shown.

[0085] 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.

[0086] 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 7 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.

[0087] 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 8 , Figure 9 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.

[0088] 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.

[0089] like Figure 10 As shown, the flow distribution pair includes a flow distribution plate 90 supported on the connecting valve block 3 and a cylinder 80 supported on the flow distribution plate 90. A first flow distribution port 92 and a second flow distribution port 93 are provided on the support surface 91 of the flow distribution plate. A triangular groove 94 or a hole is provided at the two ends of the first flow distribution port 92 and the second flow distribution port 93 respectively. The first flow distribution port 92 and the second flow distribution port 93 have a symmetrical structure.

[0090] like Figures 11-13 As shown, the swash plate 40 has a swash plate support surface 41 that matches the hydrostatic support surface 51 of the swash plate. The swash plate support surface 41 is set with a smooth surface structure, or a waist-shaped shallow groove is set on the high and low pressure sides of the swash plate support surface corresponding to the high and low pressure plunger holes, so as to reduce contact friction and improve lubrication.

[0091] The cylinder body 80 has a cylindrical configuration with a circular radial cross section and is housed within the pump housing cavity 35 of the pump housing 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, as well as a rotation center hole 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 rotating shaft 10 passes through the rotation center hole of the cylinder body 80 and is connected to the cylinder body 80 by a spline. The cylinder body 80 is cantilevered on the rotating shaft 10 in a manner that it moves synchronously with the rotating shaft 10.

[0092] It should be noted that the cylinder body 80 of this invention does not have bearings supporting it on its outer periphery. Instead, it is directly supported on the 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 body through the plunger. The shaft extension end primarily bears the centrifugal force of the plunger and cylinder body, 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 maximum speed caused by placing large bearings on the outer periphery of the cylinder body.

[0093] In this embodiment, the plunger assembly is directly inserted into the shaft extension end of the motor assembly shaft. The shaft extension end passes through the connecting valve block 3, which serves as the support for the plunger pump assembly. The inlet and outlet oil passages are also located on the connecting valve block 3. This structure has the following advantages: First, it further reduces the axial cantilever length of the shaft, significantly reducing the deflection deformation of the shaft extension end 10a of the shaft 10, thereby improving the compactness of the structure and the shaft support strength. Second, it utilizes the bearings of the motor assembly itself, thus eliminating the need for a separate bearing to support the shaft 10 in the plunger pump assembly 3, further reducing costs.

[0094] 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.

[0095] like Figure 14 , Figure 15 As shown, 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 100 fixed at the center of the swashplate 40, and the limiting structure restricts the slide plate 50 from moving outward away from the swashplate 40.

[0096] like Figure 5 , Figure 6As shown, a preferred embodiment of one of the limiting structures is illustrated. The pressure plate 60 and the slide plate 50 are connected and engaged with the swashplate via a locking structure. The locking structure includes a locking member 100, which is an integral structure. The locking member 100 is provided with a limiting plate portion 101, a rotary engagement portion 103, a locking member positioning portion 106, a locking member connecting portion 107, and an internal hexagonal hole 108. The limiting plate portion 101 engages with the pressure plate 60 to restrict the slide plate 50 from moving away from the swashplate 40. The slide plate 50 is supported on the rotary engagement portion 103 and slides with it. The locking member positioning portion 106 is inserted into the swashplate center positioning hole 44. The locking member connecting portion 107 is connected to the swashplate center connecting hole 45. A locking member limiting end face 105 is provided between the rotary engagement portion 103 and the locking member positioning portion 106, and the locking member limiting end face 105 abuts against the swashplate support surface 41.

[0097] like Figure 16 As shown, another preferred embodiment of the limiting structure is illustrated. The pressure plate 60 and the slide plate 50 are connected and engaged with the swashplate via a locking structure. The locking structure is a separate structure and includes a locking member 100, a locking member bolt 23, a locking member disc spring 24, and a locking member limiting pin 25. The locking member 100 is provided with a limiting plate portion 101, a rotary engagement portion 103, and a locking member positioning portion 106. A locking member disc spring 24 is provided between the locking member bolt 23 and the limiting plate portion 101. A locking member limiting pin 25 is provided between the locking member positioning portion 106 and the swashplate 41 to limit the rotation of the locking member 100. The locking member bolt 23 passes through the locking member 100 and is fixedly connected to the swashplate 40.

[0098] To ensure the rapid discharge of high-pressure oil leaking from the sealing strip inside the sliding plate through the gap between the sliding plate and the swashplate, and to prevent high-pressure accumulation from damaging the oil film, at least one locking member oil drain groove 104 is provided on the rotating mating part 103 of the locking member 100. The locking member oil drain groove 104 can be configured in a radial or spiral shape. At the same time, multiple limiting plate oil drain grooves 102 are provided on the limiting plate part, so that the oil leaking from the gap between the sliding plate and the swashplate is discharged from the limiting plate oil drain grooves 102 into the pump housing cavity 35.

[0099] A preload structure is provided on one side of the cylinder body. 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 center end of the cylinder body 80. The preload bolt 13 is connected to the rotating 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.

[0100] The above structural analysis demonstrates that the independent preload limiting structure used in this embodiment replaces the multiple independent slippers and the return plate-based return structure 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 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 30°. The angle is between °, which is much larger than that 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 50 and the swashplate 40, and between the cylinder block 80 and the distributor plate 90, solving the problem that traditional center spring return mechanisms can only have one preload. A limiting structure is set at the center of the pressure plate, resulting in a low contact linear velocity between the limiting structure and the pressure plate, and minimal wear on the limiting plate. Oil drain holes or grooves are provided on the rotary mating parts of the limiting structure and on the limiting plate, ensuring sufficient lubrication of the sliding parts where the sliding plate and the fasteners, as well as the sliding parts where the limiting plate and the pressure plate mate, cooperate, preventing dry friction, adhesion, and burning.

[0101] like Figures 17-19 As shown, the connecting valve block 3 has an outwardly extending connecting boss 301 and a valve block support surface 302 in the middle region. The valve block support surface 302 has a first valve block distribution port 303 and a second valve block distribution port 304. The distribution plate of the plunger pump assembly 3 is supported on the valve block support surface 302. The first valve block distribution port 303 and the second valve block distribution port 304 are respectively connected to the first distribution port 92 and the second distribution port 93 of the distribution plate. The front opening of the pump housing of the plunger pump assembly 3 is inserted into the protruding structure and connected to the connecting valve block 3. In order to prevent the distribution plate from leaking inside and causing the oil to rise and damage the shaft seal structure, an oil drain groove 305 is provided on the valve block support surface 302. The oil drain groove 305 runs through the inner and outer sides of the valve block support surface 302. The center of the connecting valve block 3 is provided with a first bearing support part 306, a shaft seal sealing part 307 and a third bearing support part 308, a first oil port 309 of the valve block and a second oil port 310 of the valve block. The first oil port 309 and the second oil port 310 of the valve block are respectively connected to the first cavity 6g of the cylinder and the second cavity 6h of the cylinder.

[0102] Example 2

[0103] like Figures 20-24 As shown, the differences lie in the structure of the plunger pump assembly, the internal oil suction and discharge method, and the hydraulic system circuit, which differ from those in Example 1. A detailed explanation follows:

[0104] like Figures 20-24The diagram illustrates the axially integrated compact power unit of this invention. This power unit is a unidirectional open power unit, comprising a motor assembly 1, a connecting valve block 3, a plunger pump assembly 4, and an oil tank 5. The motor assembly 1, connecting valve block 3, and plunger pump assembly 4 are arranged axially from left to right. The connecting valve block 3 is positioned between the motor assembly and the plunger pump assembly, with one end sealing the motor assembly housing and the other end sealing the plunger pump assembly housing and the oil tank. The front end of the motor assembly's shaft is supported on the connecting valve block and extends through it to form a shaft extension. This shaft extension is directly inserted into the rotation center hole. The shaft extension cantilever supports the cylinder body and drives the cylinder body to rotate synchronously via a key. Under hydraulic pressure, the cylinder body abuts against a distribution plate, which is supported by the connecting valve block. The connecting valve block is equipped with a distribution window, oil passage, and control valve assembly for external oil delivery and reception. The motor assembly and piston pump assembly are unidirectional motion, and the power unit hydraulic system is an open system, that is, the motor assembly and piston pump assembly can only rotate forward or reverse. The main oil circuit of the hydraulic system draws oil from the oil tank, and after the piston pump assembly acts, the high-pressure oil is delivered to the actuator. After the actuator acts, the return oil line returns the oil to the oil tank.

[0105] Firstly, the internal structures of the plunger pump assemblies differ, primarily in the structures of the sliding plate, plunger, distributor plate, and swashplate. Additionally, the inlet windows of the connecting valve block structure matched with the distributor plate also differ. The oblong orifice of the sliding plate serves as the main oil inlet and outlet passage, directly connecting to the plunger ball socket 58. Figure 23 As shown; the plunger's central bore 72 is a large-diameter through-hole structure, also serving as a channel for oil intake and / or discharge, such as... Figure 22 As shown; the first and second distribution ports of the distribution plate are generally asymmetrical structures, with one distribution port fixed as a low-pressure distribution port and the other fixed as a high-pressure distribution port; the swashplate is provided with a slot 47 opening into the pump housing cavity 35, and the first waist-shaped groove of the swashplate extends through the swashplate to the slot 47. To match the distribution plate, the structure of the valve block support surface 302 connecting the valve block 3 is also different. The valve block support surface 302 is provided with an oil inlet groove 312 and a support rib 311 communicating with the pump housing cavity 35, as shown. Figure 24 As shown.

[0106] Secondly, as shown in the figure, the oil suction and discharge methods inside the plunger pump assembly are different. The unidirectional open power unit adopts a double-end face oil distribution method. That is, the oil in the tank enters the plunger hole 81 from the oil inlet 33a of the rear end cover in two ways. One way enters the plunger hole 81 of the cylinder body from the rear end cover 33 through the first waist-shaped groove (low-pressure oil inlet groove) 42 of the swash plate, the waist-shaped hole 53 of the swash plate, and the plunger center hole 72 in sequence. The other way enters the housing cavity 35 from the rear end cover 33, and then enters the plunger hole 81 of the cylinder body through the oil inlet groove 312 on the connecting valve block, the first distribution port 92 (low-pressure port) of the distribution plate, and the waist-shaped hole 82 of the cylinder body in sequence. After being acted upon by the plunger pump assembly, the high-pressure oil enters the oil circuit of the connecting valve block from the plunger hole 81 through the waist-shaped hole 82 of the cylinder body and the second distribution port 93 (high-pressure port), and is then delivered to the outside of the actuator through the control valve group.

[0107] Secondly, the hydraulic system circuits are different, such as... Figure 21 As shown, this is a one-way open hydraulic system. The difference from Example 1 is that the motor assembly and piston pump assembly in Example 2 can only rotate forward or backward. The main hydraulic circuit draws oil from the tank, and the high-pressure oil formed by the piston pump assembly is delivered to the actuator. After the actuator's action, the return oil line returns it to the tank. The connecting valve group 3 is equipped with a control valve group, which includes at least one relief valve and one directional valve or directional throttle valve. The control valve group can also be equipped with a balance valve or a hydraulically controlled check valve as needed. Oil reversal is achieved through the directional valve (or directional throttle valve) mounted on the connecting valve block. Flow control is achieved through servo motor speed control, the control valve group, or a combination of both to control the flow rate output by the piston pump assembly.

[0108] When implemented according to the above embodiments, the following beneficial effects can be achieved:

[0109] (1) The power unit and electro-hydraulic actuator integrate the electric motor, hydraulic pump motor assembly, connecting valve block, oil tank, cylinder assembly and other components axially, eliminating the coupling and oil pipeline; it has the characteristics of compact structure, light weight, small size; low power loss and high power density; and significantly reduces the amount of hydraulic oil used; therefore, the electro-hydraulic actuator of this utility model is suitable for fields with strict requirements on space and weight, such as it can be matched with distributed hydraulic execution 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 execution systems.

[0110] (2) The motor assembly and plunger pump assembly in the power unit and electro-hydraulic actuator share the same rotating shaft. The cylinder block of the plunger pump assembly is supported on the rotating shaft. The plunger pump assembly can be designed as a modular assembly that can be directly inserted into the rotating shaft, making installation convenient.

[0111] (3) The plunger assembly is directly inserted into the shaft extension end of the motor assembly shaft. The connecting valve block has multiple structural functions. It serves as an end cover for sealing and supporting the motor assembly and plunger pump assembly, and can also serve as a carrier for oil inlet and outlet and control valve group. The structure is highly compact, the number of structural parts is significantly reduced, further reducing costs. At the same time, the axial dimension is significantly reduced, significantly reducing the space occupied by the actuator.

[0112] (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.

[0113] (5) 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, improves the oil film stability, and has good high and low speed performance, so that the hydraulic pump assembly has higher speed and longer service life to match the working conditions of high-speed motor.

[0114] (6) By combining dual-function servo motor components and four-quadrant piston pump components under different operating conditions, functions such as variable speed volume speed regulation, reversing, and energy recovery can be achieved. Therefore, it is particularly suitable for fields such as electric medium and large-sized forklifts and electric lifting trucks that require energy recovery and energy saving, which can significantly reduce the overall cost and extend the battery life of the equipment.

[0115] (7) 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.

[0116] 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. An axially integrated compact power unit, characterized in that, include: The motor assembly (1) is connected to the plunger pump assembly (4) and used to provide electric drive or generate electricity; the front end of the shaft (10) of the motor assembly (1) is supported on the connecting valve block (3) and passes through the connecting valve block (3) to form a shaft extension end; The plunger pump assembly (4) includes a pump housing, a flow distribution pair, a plunger (70) pair and a sliding plate pair are provided inside the pump housing. The pump housing and the flow distribution pair of the plunger pump assembly (4) are connected to the connecting valve block (3). The plunger (70) pair includes a cylinder (80) and a plurality of plungers (70). One end of the plunger (70) is engaged with the cylinder (80) and the other end of the plunger (70) is engaged with the sliding plate pair. The shaft extension end is connected to and supports the cylinder (80) in a cantilever state. The shaft extension end, in conjunction with the cylinder (80), drives the plunger (70) to rotate to realize the reciprocating motion of the plunger (70) for oil suction and oil pressure. A connecting valve block (3) is disposed between the motor assembly (1) and the plunger pump assembly (4). One side of the connecting valve block (3) encloses the housing of the motor assembly (1), and the other side encloses the pump housing and oil tank (5) of the plunger pump assembly (4). The connecting valve block (3) is provided with a distribution window, an oil passage and a control valve group for conveying and receiving oil. The distribution window and oil passage are connected to the distribution pair of the plunger pump assembly (4). The oil tank (5) is used to contain hydraulic oil and the plunger pump assembly (4). The shaft extension end extends into the oil tank (5) and the plunger pump assembly (4) is located in the oil tank (5) and submerged in hydraulic oil. The pump housing is provided with an oil port that communicates with the oil tank (5).

2. The axially integrated 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 motor end cover; the other end of the motor housing is closed by a valve block (3), the rotating shaft (10) extends from inside the motor housing to the outside and a rotor assembly is connected to the rotating shaft (10), a stator assembly corresponding to the rotor assembly is provided on the inner surface of the motor housing, the rear part of the rotating shaft (10) is connected to the motor housing by a second bearing, and the front part of the rotating shaft (10) is connected to the valve block (3) by a first bearing.

3. The axially integrated compact power unit according to claim 1 or 2, characterized in that: An oil seal assembly is provided between the rotating shaft (10) and the connecting valve block (3) to prevent hydraulic oil from entering the motor assembly (1).

4. The axially integrated compact power unit according to claim 1 or 2, characterized in that: A third bearing is provided between the rotating shaft (10) and the connecting valve block (3).

5. The axially integrated compact power unit according to claim 1, characterized in that: The connecting valve block (3) is provided with a connecting boss (301). The flow distribution pair of the plunger pump assembly (4) is tightly fitted with the end face of the connecting boss (301). The flow distribution plate (90) of the flow distribution pair is attached to the end face of the connecting boss (301) and communicates with the flow distribution window of the connecting boss (301). The front end of the pump housing of the plunger pump assembly (4) forms an opening and is fixed to the side surface of the connecting boss (301).

6. The axially integrated compact power unit according to claim 1, characterized in that: The slide plate assembly includes a swashplate and a slide plate supported on the swashplate. The plunger (70) is connected to the slide plate via a pressure plate (60). The front end face of the slide plate is provided with plunger ball sockets (58) corresponding to the plunger (70). The plunger ball sockets (58) extend through the central oil hole and the slide plate waist-shaped hole to the rear end face of the slide plate. The rear end face of the slide plate is also provided with a sealing structure and an oil draining structure. The pressure plate (60) is fitted to the front end face of the slide plate and is provided with a pressure plate (60) hole corresponding to the plunger ball socket (58). The pressure plate (60) hole cooperates with the plunger (70) so that the end of the plunger (70) is always located in the plunger ball socket (58).

7. The axially integrated compact power unit according to claim 6, characterized in that: The pressure plate (60) and the slide are connected and cooperate with the swashplate through a fastening structure. The fastening structure includes a fastening member, which is provided with a limiting plate part, a rotary fitting part, a fastening member positioning part, and a fastening member connecting part. The limiting plate part cooperates with the pressure plate (60) to keep the slide plate and the swashplate in close contact. The slide plate is rotatably supported on the rotary fitting part. The fastening member positioning part is inserted into the center positioning hole of the swashplate. The fastening member connecting part is connected to the center connecting hole of the swashplate. A fastening member limiting end face is provided between the rotary fitting part and the fastening member positioning part. The fastening member limiting end face abuts against the swashplate support surface.

8. The axially integrated compact power unit according to claim 6, characterized in that: The pressure plate (60) and the slide are connected to the swashplate via a locking structure. The locking structure includes a locking component, a locking component bolt, a locking component disc spring, and a locking component limiting pin. The locking component includes a limiting plate part, a rotary fitting part, and a locking component positioning part. The locking component disc spring is disposed between the locking component bolt and the limiting plate. The locking component limiting pin is disposed between the locking component positioning part and the swashplate and is used to keep the locking component circumferentially fixed. The locking component bolt passes through the locking component and is fixedly connected to the swashplate.

9. The axially integrated compact power unit according to claim 1, characterized in that: The cylinder body (80) 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 cylinder body (80). The elastic preload applies an elastic preload force to the cylinder body (80) and causes the cylinder body (80) and the flow distribution pair to press against the connecting valve block (3).

10. An electro-hydraulic actuator comprising an axially integrated compact power unit as described in any one of claims 1 to 9, characterized in that: The hydraulic cylinder assembly (6) is connected to the power unit. The hydraulic cylinder assembly (6) includes a cylinder barrel (6a) and a piston rod (6b) that cooperate with each other. One end of the cylinder barrel (6a) is provided with a connecting block (6e) and connected to the connecting valve block (3). The piston rod (6b) divides the cylinder barrel (6a) into two action chambers. Both action chambers are provided with oil ports. The oil passage of the connecting valve block (3) extends to the connecting block (6e) and is connected to the oil ports of the two action chambers respectively.

11. The electro-hydraulic actuator according to claim 10, characterized in that: The motor assembly (1) is a servo motor and is connected in conjunction with the driver and controller (2). The servo motor is used in conjunction with the driver and controller (2) to perform variable speed volume control on the plunger pump assembly (4) to adjust the flow rate of the output oil.

12. The electro-hydraulic actuator according to claim 10 or 11, characterized in that: The motor assembly (1) adopts a servo motor with dual functions of power generation and drive, and the plunger pump assembly (4) adopts a bidirectional four-quadrant plunger (70) pump; the plunger pump assembly (4) works in pump mode or motor mode. When the plunger pump assembly (4) works in pump mode, the servo motor assembly (1) works in drive mode, and when the plunger pump assembly (4) works in motor mode, the servo motor assembly (1) works in power generation mode.

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