Integrated Electro-Hydraulic Actuator

Abstract

An example electro-hydraulic actuator includes an assembly including: a housing; a hydraulic cylinder actuator disposed within the housing and including a cylinder and a piston, the piston dividing an interior space of the cylinder into a first chamber and a second chamber, the hydraulic cylinder actuator being unbalanced; an accumulator disposed within the housing and including an annular fluid chamber surrounding the cylinder of the hydraulic cylinder actuator, the accumulator configured to provide a boost fluid flow comprising a difference between a first fluid flow rate and a second fluid flow rate or to receive an excess fluid flow; and an electric motor disposed within the housing and configured to (i) provide a flow source; and (ii) drive the pump to provide fluid flow to the first chamber or the second chamber of the hydraulic cylinder actuator, thereby driving the piston.

Description

[Technical Field]

[0001] The present invention relates to an integrated electro-hydraulic actuator. (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 63 / 493,002, filed March 30, 2023, the entire contents of which are incorporated herein by reference as if fully set forth herein. [Background technology]

[0002] Work machines, such as hydraulic excavators, wheel loaders, loading shovels, backhoe excavators, mining equipment, industrial machinery, and the like, may have one or more operating components, such as lifting and / or tilting arms, booms, buckets, steering features, swing features, locomotion means, etc. Typically, in such machines, a prime mover drives a hydraulic pump, which provides fluid to the actuators. Open-center or closed-center valves can control fluid flow to the actuators. Such valves are characterized by significant power losses due to throttling of the flow through the valve. Furthermore, such conventional systems may involve providing a constant flow rate from the pump regardless of the number of actuators used. Therefore, such systems are characterized by low efficiency.

[0003] Therefore, it may be desirable to have a hydraulic system that increases the efficiency of a work machine. With the recent trend toward electrification due to emission regulations, some hydraulic systems are configured to include decentralized or distributed electrohydraulic actuators (EHA), which reduce throttling losses and allow for energy recovery from overloads.

[0004] An exemplary EHA may include an electrohydraulic power unit having an electric motor driving a pump, which provides fluid flow to an actuator, such as a linear hydraulic actuator cylinder or a hydraulic motor. Typically, standard components are arranged and connected together to form the EHA. For example, the electric motor is coupled to the pump, and the electric motor is axially spaced from the pump and connected to the pump via a shaft. The electric motor and pump may be positioned, for example, next to the hydraulic cylinder.

[0005] Additionally, a fluid reservoir may be located next to the pump, and a separate valve block or a separate manifold connects the pump, reservoir, and hydraulic cylinder via fluid lines (pipes, hoses, etc.).

[0006] While such configurations involve the use of standard components, they may not be suitable for many applications, such as construction equipment (e.g., excavators, wheel loaders, etc.), that are subject to impacts, rocks, debris, etc. In particular, such configurations may not provide adequate structural integrity in environments where rocks and debris may continually impact the EHA components. Furthermore, such configurations have low power to volume density because they occupy a large amount of space. Also, the multiple fluid connections connecting the various components present potential leak points, thus reducing the reliability of the system.

[0007] Therefore, it may be desirable to integrate the components of an EHA into a compact, self-contained configuration with no or minimal external connections, thereby improving the performance and reliability of the EHA. It is with respect to these and other issues that the disclosure herein presents considerations. Summary of the Invention

[0008] The present disclosure describes configurations for integrated electro-hydraulic actuators.

[0009] In particular, the present disclosure describes an electro-hydraulic actuator in which an accumulator is integrated with a hydraulic cylinder actuator, whereby the fluid chamber of the accumulator is formed within a housing of the electro-hydraulic actuator and surrounds a cylinder of the hydraulic cylinder actuator disposed within the housing.

[0010] The present disclosure also describes a method for assembling an electrohydraulic actuator.

[0011] The foregoing summary is illustrative only and is not intended to be limiting in any way. In addition to the exemplary aspects, configurations, and features described above, further aspects, configurations, and features will become apparent by reference to the drawings and the following detailed description.

[0012] The novel features believed characteristic of the illustrative examples are set forth in the appended claims. However, the illustrative examples, as well as preferred modes of use, further objects and description thereof, can best be understood by reference to the following detailed description of illustrative examples of the present disclosure, read in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram of a hydraulic system according to an exemplary configuration. [Figure 2] FIG. 1 is a perspective view of an electro-hydraulic actuator integrating an electro-hydraulic power unit, an accumulator, a valve, and a hydraulic actuator cylinder into an assembly according to an exemplary configuration. [Figure 3] 3 is a cross-sectional side view of the electro-hydraulic actuator of FIG. 2 according to an exemplary configuration. [Figure 4] 3 is a perspective cross-sectional view of the electro-hydraulic actuator of FIG. 2 according to an exemplary configuration. [Figure 5] FIG. 1 is a perspective view of a first housing portion and an electric motor and pump assembly disposed within the first housing portion according to an exemplary configuration. [Figure 6] 1 is a cross-sectional side view of a first housing portion and an assembly disposed within the first housing portion according to an exemplary configuration. [Figure 7] 3 is a partial cross-sectional perspective view of the electro-hydraulic actuator of FIG. 2 according to an exemplary configuration, showing the connector block attached to the manifold. [Figure 8] FIG. 8 is a rear view of the connector block of FIG. 7 according to an exemplary configuration. [Figure 9] 3 is a partial cross-sectional perspective view of the electrohydraulic actuator of FIG. 2 showing the manifold according to an exemplary configuration. [Figure 10] FIG. 10 is a rear view of the manifold of FIG. 9 according to an exemplary configuration. [Figure 11] FIG. 10 is a side view of the manifold of FIG. 9 according to an exemplary configuration. [Figure 12] FIG. 10 is a front view of the manifold of FIG. 9 according to an exemplary configuration. [Figure 13] FIG. 5 is a flowchart diagram of a method for assembling the electro-hydraulic actuator of FIGS. 2-4, according to an exemplary configuration. DETAILED DESCRIPTION OF THE INVENTION

[0014] An exemplary hydraulic machine, such as an excavator, can use multiple hydraulic actuators to perform various tasks. Many electric hybrid and battery-powered machines use multiple hydraulic cylinders and electric motors to perform various tasks. It is desirable to increase the efficiency of the machine, which allows for the reduction of the size of the hybrid internal combustion engine and / or battery, while also reducing the thermal management costs of the battery.

[0015] An exemplary system approach to increasing efficiency is to provide an on-demand closed-loop system with a dedicated hydrostatic pump and electric motor for each actuator on the machine. This approach can increase efficiency by enabling the recovery of electrical energy from hydraulic energy while eliminating the valve metering, overpressure, and standby losses characteristic of conventional systems.

[0016] The combination of a hydrostatic pump and an electric motor is sometimes referred to as an electrohydraulic power unit. As described in more detail below, when such an electrohydraulic power unit is used to operate an unbalanced actuator (e.g., a hydraulic cylinder actuator with chambers having different volumes), a variable volume reservoir (e.g., an accumulator) can be used as a fluid source to provide boost fluid to the unbalanced actuator. Such a reservoir thus compensates for the difference in fluid flow rate between the fluid provided to the actuator and the fluid discharged from the actuator. If the fluid flow rate discharged from the actuator is greater than the fluid flow rate provided to the actuator, the reservoir can also absorb the excess flow.

[0017] Additionally, various valves may be used to define paths between the reservoir, the electro-hydraulic power unit, and the hydraulic actuator. Thus, the electro-hydraulic actuator may include a hydraulic cylinder actuator, a reservoir (e.g., an accumulator), a valve block or manifold, and various connections between these components.

[0018] Disclosed herein is an assembly that integrates various components of an electrohydraulic actuator, thereby improving the system's power output and reliability relative to its volumetric density. One example of the disclosed assembly includes a housing within which a compact electrohydraulic power unit (e.g., an electric motor and pump) is disposed. A valve block or manifold integrating various valves of the electrohydraulic actuator is also disposed within the housing. In one example, a connector block is also integrated within the housing, thereby defining fluid paths between the various components of the electrohydraulic actuator. A variable volume reservoir (e.g., an accumulator) is disposed around the hydraulic cylinder, with the reservoir surrounding at least a portion of the cylinder. This configuration provides a compact, efficient, and reliable assembly.

[0019] 1 is a schematic diagram of a hydraulic system 100 that uses an accumulator 102 as a source of boost fluid, according to an exemplary configuration. The hydraulic system 100 includes a hydraulic cylinder actuator 104 having a cylinder 106 and a piston 108 slidably received within the cylinder 106 and configured to move linearly within the cylinder 106.

[0020] The piston 108 includes a piston head 110 and a rod 112 that extends from the piston head 110 along the central longitudinal axis of the cylinder 106. The rod 112 can be coupled to a load representing, for example, a machine element, such as a boom, arm, or bucket, and any force acting on the machine element. The piston head 110 divides the interior space of the cylinder 106 into a first chamber 116 and a second chamber 118.

[0021] The first chamber 116 may be referred to as the head-side chamber because fluid in the first chamber 116 interacts with the piston head 110, and the second chamber 118 may be referred to as the rod-side chamber because the rod 112 is partially disposed in the second chamber 118. Fluid may flow into and out of the first chamber 116 through workport 117 and into and out of the second chamber 118 through workport 119.

[0022] The diameter of the piston head 110 is D H and the diameter of the rod 112 may be D R Thus, the fluid in the first chamber 116 interacts with the cross-sectional area of ​​the piston head 110, which may be referred to as the piston head area, JPEG2026505902000002.jpg10150. Meanwhile, the fluid in the second chamber 118 interacts with the annular surface area of ​​the piston 108, which is equal to the piston annular area It is sometimes called JPEG2026505902000003.jpg11161.

[0023] Area A Annular is the piston head area A H Therefore, when the piston 108 extends (e.g., moves to the right in FIG. 1 ) or retracts (e.g., moves to the left in FIG. 1 ) within the cylinder 106, the fluid flow rate Q entering or leaving the first chamber 116 is A is the fluid flow rate Q leaving or entering the second chamber 118 a More than.

[0024] In particular, if the piston 108 is moving at a particular velocity V, then Q A =A H V is Q a =A Annular More than V. The difference in flow is Q A -Q a =A RV can be determined as: R is the cross-sectional area of ​​the rod 112, JPEG2026505902000004.jpg10150. In this configuration, the hydraulic cylinder actuator 104 may be referred to as an unbalanced actuator because the fluid flow to / from the first chamber 116 is not equal to the fluid flow to / from the second chamber 118.

[0025] The hydraulic system 100 includes an electro-hydraulic power unit 120 having an electric motor that drives a pump. The electro-hydraulic power unit 120 is configured to control the amount and direction of hydraulic fluid flow into and out of the hydraulic cylinder actuator 104. Such control is achieved by controlling the speed and direction of the electric motor and a pump that is configured as a bidirectional fluid flow source.

[0026] The electro-hydraulic power unit 120 has a first pump port 122 connected to the first chamber 116 of the hydraulic cylinder actuator 104 by a first fluid line 124 and a second pump port 126 connected to the second chamber 118 of the hydraulic cylinder actuator 104 by a second fluid line 128. Throughout this specification, the term "fluid line" is used to indicate one or more fluid passages, conduits, etc. that provide the indicated connectivity.

[0027] The first pump port 122 and the second pump port 126 are configured to function as both an inlet port and an outlet port based on the direction of rotation of the rotor of the electric motor driving the pump. When the rotor of the electric motor rotates in a first rotational direction, the pump draws fluid through the first pump port 122 (in this case, the inlet port) and pushes fluid out the second pump port 126 (in this case, the outlet port). Conversely, when the rotor rotates in a second rotational direction, the pump draws fluid through the second pump port 126 (in this case, the inlet port) and pushes fluid out the first pump port 122 (in this case, the outlet port).

[0028] Additionally, as described in more detail below, the electrohydraulic power unit 120 is configured to operate in a pump mode and a motor mode. In the pump mode, the electric motor drives a pump, which provides fluid to drive the piston 108 against a resistive load.

[0029] In motoring mode (e.g., regenerative mode), the hydraulic cylinder actuator 104 is subjected to an auxiliary load (e.g., the direction of the force acting on the piston 108 is the same as the direction of movement of the piston 108). Thus, in motoring mode, fluid discharged from the hydraulic cylinder actuator 104 and returning to the electrohydraulic power unit 120 drives a pump, which drives an electric motor. In this case, the electric motor operates as a generator, and fluid energy received by the electrohydraulic power unit 120 is converted by the electric motor into electrical power. The electrical power generated in this mode can be stored, for example, in a battery. Thus, the electric motor may be generally referred to as an electric machine configured to operate as both an electric motor and a generator.

[0030] 1, the pump of the electro-hydraulic power unit 120 and the hydraulic cylinder actuators 104 are configured in a closed circuit, i.e., a closed-loop hydraulic circuit. The term "closed circuit" is used herein to indicate that fluid is recirculated within a loop between the pump and the hydraulic cylinder actuators 104. Specifically, in the hydraulic system 100, the pump provides fluid to the work port 117 through the first pump port 122 or to the work port 119 through the second pump port 126, and fluid discharged from the other work port returns to the corresponding port of the pump. Thus, fluid is recirculated between the pump and the hydraulic cylinder actuators 104.

[0031] In one example, the pump may be a fixed displacement pump, where the fluid flow rate provided by the pump is controlled by the speed of the electric motor (i.e., the rotational speed of the rotor of the electric motor coupled to the pump). For example, the pump may have a particular pump displacement P D and this particular pump capacity P D is the volume of fluid produced or delivered by a pump, e.g., in cubic inches per revolution (in 3 Electric motors can be run at a commanded speed in revolutions per minute (RPM). Therefore, the speed of an electric motor is determined by P D cubic inches per minute (in 3 The fluid flow rate Q (in sq. / min) is determined.

[0032] The flow rate Q determines the linear velocity of the piston 108. For example, when an electric motor drives the pump in a first rotational direction, thereby providing fluid to the first chamber 116, the piston 108 moves at a velocity V1=Q / A H On the other hand, when the electric motor drives the pump in a second rotational direction, thereby providing fluid to the second chamber 118, the piston 108 may extend at a speed V2=Q / A Annular It may be shrunk by

[0033] As previously mentioned, the hydraulic cylinder actuator 104 is in an imbalance state in which the fluid flow rate provided to or discharged from the first chamber 116 is greater than the fluid flow rate provided to or discharged from the second chamber 118. Thus, the fluid flow rate provided to or received at the first pump port 122 (to or from the first chamber 116) is greater than the fluid flow rate provided to or received at the second pump port 126 (to or from the second chamber 118). This mismatch between the fluid flow rate provided by the pump and the fluid flow rate received by the pump can cause cavitation, which can cause the pump to malfunction.

[0034] The hydraulic system 100 includes a variable volume reservoir, such as an accumulator 102, that is configured to augment fluid flow or accept excess flow, thereby compensating for fluid flow mismatches. The accumulator 102 may be configured to provide fluid flow at a particular pressure range, for example, between 0 and 15 bar. As a specific example, the accumulator 102 may provide fluid at a pressure level of 4 to 5 bar.

[0035] The accumulator 102 is configured to provide boost flow or accept excess flow via a boost flow line 132. In one example, the accumulator 102 can provide or accept fluid directly from the boost flow line 132. In another example, the accumulator 102 provides boost flow to or accepts excess flow from the boost flow line 132 via the electro-hydraulic power unit 120. In particular, as described in more detail below, the electric motor and pump of the electro-hydraulic power unit 120 may be integrated into an assembly having an internal chamber through which the boost or excess flow flows to or from the accumulator 102 to cool the electric motor without the use of a separate cooling arrangement.

[0036] In one example, the accumulator 102 is configured as a pressure storage reservoir in which an incompressible working fluid is held under pressure applied by an external mechanical energy source. The external mechanical energy source may be an engine, a spring, a weight, or compressed gas. For example, the accumulator 102 may have a cylindrical chamber with a piston therein. The piston may be spring loaded or pressurized by gas disposed on one side of the piston.

[0037] When fluid is provided to the accumulator 102 (which acts as a sealed container with a fixed volume), the volume of fluid in the accumulator 102 increases, and the pressure in the accumulator 102 increases due to spring or gas pressure acting on the other side of the piston. The accumulator 102 can then provide pressurized fluid to the boost flow line 132.

[0038] Other types of accumulators may be used. For example, the accumulator 102 may be a bladder-type accumulator. Such an accumulator may include a nitrogen-filled bladder fitted to a welded or forged steel pressure vessel. The bladder is fabricated from an elastic material (elastomer), such as rubber. The gas pre-charge pressure may be adjusted via a gas inlet / outlet valve on top of the bladder-type accumulator. When the pressure level of the working fluid in the accumulator decreases, the compressed gas in the bladder expands, forcing the stored fluid into the hydraulic circuit. Conversely, when fluid is provided to the accumulator, the fluid compresses the bladder, thereby increasing the pressure level of the fluid in the accumulator. In other examples, the accumulator 102 may be a diaphragm-type accumulator or a spring-type accumulator, in which a diaphragm or spring is used instead of compressed gas.

[0039] The boost flow line 132 is connected to a reverse shuttle valve 130, which fluidly connects the chambers 116, 118 of the cylinder 106 to the boost flow line 132 in response to the pressure differential across the pump (i.e., the pressure differential between the first fluid line 124 and the second fluid line 128). In one example, the reverse shuttle valve 130 may be configured as a pilot-operated three-position shuttle valve having a shuttle element (e.g., a poppet or spool) therein whose position is determined by the pressure differential across the pump.

[0040] The reverse shuttle valve 130 may have a first pilot port 134 fluidly connected to the first fluid line 124 and a second pilot port 136 fluidly connected to the second fluid line 128. The reverse shuttle valve 130 also has a boost port 138 fluidly connected to the boost flow line 132. The reverse shuttle valve 130 is actuated by the pressure differential between the fluid lines 124, 128, thereby connecting (i) the second fluid line 128 to the boost flow line 132 when the pressure in the first fluid line 124 exceeds the pressure level of the second fluid line 128, or (ii) the first fluid line 124 to the boost flow line 132 when the pressure in the second fluid line 128 exceeds the pressure level of the first fluid line 124.

[0041] For example, when the pump is driven by an electric motor, thereby supplying fluid to the first fluid line 124 and extending the piston 108, a pressure differential across the pump causes the shuttle element of the reverse shuttle valve 130 to transition, thereby connecting the boost port 138 to the second pilot port 136, thereby fluidly connecting the second fluid line 128 to the boost flow line 132 while blocking flow from the first fluid line 124 to the boost flow line 132. The reverse shuttle valve 130 thus provides a fluid flow path from the boost flow line 132 to the second pump port 126, compensating for the difference between the fluid flow rate provided to the first chamber 116 and the fluid flow rate returning from the second chamber 118 through the second fluid line 128.

[0042] Conversely, when the pump is driven in the opposite direction, causing the piston 108 to retract, the pressure differential across the pump transitions the shuttle element of the reverse shuttle valve 130, connecting the first pilot port 134 to the boost port 138, thereby fluidly connecting the first fluid line 124 to the boost flow line 132 while blocking flow from the second fluid line 128 to the boost flow line 132. The reverse shuttle valve 130 thus provides a fluid flow path for excess fluid flow from the first chamber 116 through the first fluid line 124 back to the boost flow line 132. Different modes of operation of the hydraulic system 100 and the reverse shuttle valve 130 are described below.

[0043] The term "reverse" is applied to the reverse shuttle valve 130 because it differs from a conventional shuttle valve. A conventional shuttle valve may have a first inlet, a second inlet, and an outlet. The valve element moves freely within such a conventional shuttle valve, such that when pressure from a fluid is applied through a particular inlet, the pressure from the fluid pushes the valve element toward the opposite inlet. This movement allows fluid to flow from a particular inlet to the outlet while blocking the opposite inlet. In this way, two different fluid sources can provide pressurized fluid to the outlets without reverse flow from one source to the other. The reverse shuttle valve 130 does not have a dedicated outlet port and instead provides fluid flow either from the boost port 138 to the second pilot port 136 or from the first pilot port 134 to the boost port 138.

[0044] In the exemplary configuration described above, the reverse shuttle valve 130 is a pilot-operated valve, and the shuttle element moves in response to the pressure differential between the fluid lines 124, 128. In other examples, the reverse shuttle valve 130 may be electrically actuated, whereby an electronic controller of the hydraulic system 100 can provide an electrical signal that moves the shuttle element based on pressure levels sensed in the fluid lines 124, 128.

[0045] In one example, hydraulic system 100 further includes a filter 140 configured to filter the fluid, thereby removing any contaminants in the fluid. In this example, a check valve 142 may be used to prevent backflow from second fluid line 128 to filter 140 or boost flow line 132.

[0046] In one example, the hydraulic system further includes a shuttle valve 144, a metering valve 146, and a pressure relief valve 148. The metering valve 146 is configured as a throttle valve that meters or throttles the fluid flow discharged from the hydraulic cylinder actuator 104, thereby slowing the speed of the piston 108, as described below. For example, the metering valve 146 may be a proportional valve that is electronically actuated via a solenoid 150. An electrical command signal sent from a controller of the hydraulic system 100 to the solenoid 150 controls the fluid flow through the metering valve 146.

[0047] The shuttle valve 144 has a first inlet port 152 fluidly connected to the first fluid line 124 and the first chamber 116, and a second inlet port 154 fluidly connected to the second fluid line 128 and the second chamber 118. The shuttle valve 144 also has an outlet port 156 fluidly connected to an inlet port 158 ​​of the metering valve 146. An outlet port 160 of the metering valve 146 is fluidly connected to the boost flow line 132.

[0048] When the pressure level of the fluid in the first chamber 116 is higher than the pressure level of the fluid in the second chamber 118, the shuttle valve 144 provides a fluid path from the first inlet port 152 (and the first chamber 116) to the outlet port 156. Conversely, when the pressure level of the fluid in the second chamber 118 is higher than the pressure level of the fluid in the first chamber 116, the shuttle valve 144 provides a fluid path from the second inlet port 154 (and the second chamber 118) to the outlet port 156.

[0049] Occasionally, the hydraulic cylinder actuator 104 may be subjected to large forces that can cause overpressure in one of the chambers 116, 118. To protect the hydraulic cylinder actuator 104 from possible overpressure, the hydraulic system 100 includes a pressure relief valve 148.

[0050] The pressure relief valve 148 is configured to protect the chambers 116, 118. Fluid having a higher pressure level between the chambers 116, 118 flows through the shuttle valve 144 to the pressure relief valve 148. When the pressure level reaches a threshold, e.g., 300 bar or 4350 lb / in 2 (psi), when the metering valve 146 is closed (deactivated), the pressure relief valve 148 opens, thereby allowing such high pressure fluid to escape to the boost flow line 132.

[0051] Other types of valves may be added to the hydraulic system 100. For example, load holding valves may be added. Such load holding valves may be configured as pilot operated check valves, counterbalance valves, on / off electronic control valves, etc.

[0052] The hydraulic system 100 is configured to operate in at least four modes of operation. The first mode of operation involves extending the piston 108 while the piston 108 is subjected to a resistive load (e.g., moving the piston 108 to the right in FIG. 1 ). The term "resistive" indicates that the load exerts a force on the piston 108 in a direction opposite to the direction of movement of the piston 108. The second mode of operation involves extending the piston 108 while the piston 108 is subjected to an auxiliary load. The term "assisted" indicates that the load exerts a force on the piston 108 in the same direction as the direction of movement of the piston 108. This may occur, for example, when the movement of the piston 108 is assisted by gravity.

[0053] In the first and second modes of operation, the accumulator 102 is configured to provide boost flow through the electric motor to the boost flow line 132. In other words, the accumulator 102 operates in a discharge mode in which fluid is discharged from the accumulator 102.

[0054] The third mode of operation involves retracting the piston 108 while the piston 108 is subjected to a resistive load (e.g., moving the piston 108 to the left in FIG. 1 ). The fourth mode of operation involves retracting the piston 108 while the piston 108 is subjected to an auxiliary load. In the third and fourth modes of operation, the accumulator 102 is configured to receive excess flow from the boost flow line 132 through the electric motor. In other words, the accumulator 102 operates in a charging mode, in which the excess flow is used to charge the accumulator 102.

[0055] In particular, to extend the piston 108 while the piston 108 is subjected to a resistive load (a first mode of operation), the controller of the hydraulic system 100 can send a command signal to the power electronics module, which operates the electric motor and drives the pump of the electro-hydraulic power unit 120 in a first rotational direction. Thus, the fluid flow rate Q A is provided from the first pump port 122 through the first fluid line 124 to the first chamber 116, thereby extending the piston 108. As the piston 108 extends, fluid is drawn from the second chamber 118 at a fluid flow rate Q a into the second fluid line 128 at .

[0056] At the same time, the accumulator 102 provides a compensation flow or boost flow Q in the boost flow line 132. accSpecifically, the high pressure fluid in the first fluid line 124 transitions the reverse shuttle valve 130 to a state that fluidly connects the boost flow line 132 to the second fluid line 128. Thus, the reverse shuttle valve 130 operates with the second pilot port 136 fluidly connected to the boost port 138, and thus the boost flow provided by the accumulator 102 combines with the fluid discharged from the second chamber 118 in the second fluid line 128. The compensation flow or boost flow Q provided by the accumulator 102 is acc Q acc =A R V is determined as R is the cross-sectional area of ​​the rod 112, and V is the velocity of the piston 108. Then, the combined flow Q from the second chamber 118 and the accumulator 102 A =Q a +Q acc flows to the second pump port 126.

[0057] Thus, the total flow received at the second pump port 126 is equal to the total flow provided by the pump to the first chamber 116 through the first pump port 122 and the first fluid line 124. In particular, the fluid returning from the second chamber 118 to the second pump port 126 through the second fluid line 128 has a low pressure level, and thus the boost flow Q provided by the accumulator 102. acc may be provided at a low pressure level that matches the low pressure level of the flow returning to the second pump port 126. For example, the boost flow may have a pressure level in the range of 0 to 15 bar, compared to the high pressure level of 300 bar that may be provided by the pump to the first chamber 116 to extend the piston 108 against a resistive load.

[0058] In this mode, the electro-hydraulic power unit 120 (i.e., electric motor and pump) supplies hydraulic power P to the hydraulic cylinder actuator 104. EHU , which causes the piston 108 to move at a particular speed against a resistive load.

[0059] The second mode of operation involves extending the piston 108 while the piston 108 is subjected to an auxiliary load (extending the piston 108 at a particular rate while the auxiliary load acts in the same direction). In this mode, the fluid in the first fluid line 124 is a low pressure fluid, while the fluid discharged from the second chamber 118 to the second fluid line 128 may be a high pressure fluid. The pump generates a flow of fluid discharged from the second chamber 118 at a flow rate Q at the second pump port 126. a and therefore the same flow rate Q a In this case, high pressure fluid received at the second pump port 126 drives a pump, which in turn drives the electric motor in a regenerative mode, thereby consuming power P rather than consuming power. EHU is generated.

[0060] Additionally, the high pressure fluid in the second fluid line 128 transitions the reverse shuttle valve 130 to a state that fluidly connects the boost flow line 132 to the first fluid line 124. In particular, the reverse shuttle valve 130 operates with the first pilot port 134 fluidly connected to the boost port 138, which in turn connects the boost flow Q provided by the accumulator 102 to the boost port 138. acc flows through boost flow line 132 to boost port 138 and then to first pilot port 134, thereby increasing the fluid flow Q provided by the pump in first fluid line 124. a The combined fluid flow Q A =Q a +Q acc is provided to a first chamber 116 of the hydraulic cylinder actuator 104.

[0061] In particular, the fluid provided by the pump to the first fluid line 124 has a low pressure level. Therefore, the boost flow Q provided by the accumulator 102 acc can be provided at a low pressure level (e.g., 0-15 bar) that matches the low pressure level of the flow provided through the first pump port 122.

[0062] A third mode of operation involves retracting the piston 108 while the piston 108 is subjected to a resistive load. To retract the piston 108 (e.g., to move the piston 108 to the left in FIG. 1 ), the controller of the hydraulic system 100 can send a command signal to the power electronics module, which operates the electric motor to drive the pump in a second rotational direction opposite the first rotational direction associated with extending the piston 108. Thus, the fluid flow rate Q of the high-pressure fluid a is provided from the second pump port 126 through the second fluid line 128 to the second chamber 118, causing the piston 108 to retract. As the piston 108 retracts, fluid is pumped from the first chamber 116 at a fluid flow rate Q A into the first fluid line 124 at .

[0063] The pump generates a fluid flow rate Q at the second pump port 126. a , the pump will accept the same amount of fluid flow at the first pump port 122. A and Q a The difference in flow between the first and second pilot ports 134 of the reversing shuttle valve 130 is diverted to the accumulator 102 at a flow rate Q acc , which charges the accumulator 102.

[0064] In particular, the high pressure fluid in the second fluid line 128 causes the reverse shuttle valve 130 to transition to a state where the boost flow line 132 is fluidly connected to the first fluid line 124. Specifically, the reverse shuttle valve 130 operates with the first pilot port 134 fluidly connected to the boost port 138, thus providing a flow differential or excess flow Q acc =Q A -Q aflows from first fluid line 124 to first pilot port 134, then to boost port 138, into boost flow line 132, and then (through the casing or housing of the electric motor and pump) to accumulator 102, thereby charging accumulator 102. In this mode, electro-hydraulic power unit 120 (i.e., electric motor and pump) provides hydraulic power P to hydraulic cylinder actuator 104. EHU , which causes the piston 108 to retract at a particular rate against a resistive load.

[0065] A fourth mode of operation involves retracting the piston 108 while the piston 108 is subjected to an auxiliary load. In this mode of operation, the piston 108 can be retracted at a particular rate while subjected to an auxiliary load acting in the same direction.

[0066] When the piston 108 retracts under the assistance of a load, the pump provides low pressure fluid to the second fluid line 128 through the second pump port 126, while the fluid expelled from the first chamber 116 to the first fluid line 124 may be high pressure fluid. The pump provides a flow rate Q from the first chamber 116 to the first pump port 122. A and thus receives the flow discharged at the same flow rate Q A In this case, the high pressure fluid received via the first fluid line 124 drives a pump, which in turn drives the electric motor in a regenerative mode, thereby consuming power P rather than consuming power. EHU is generated.

[0067] The pump delivers a fluid flow rate Q to the second fluid line 128. A while the second chamber 118 provides a fluid flow rate Q a Accept the difference in flow or excess flow Q A -Q a is the accumulator flow Q acc , which charges the accumulator 102.

[0068] In particular, the high pressure fluid in the first fluid line 124 causes the reverse shuttle valve 130 to transition to a state where the boost flow line 132 is fluidly connected to the second fluid line 128. Specifically, the reverse shuttle valve 130 operates with the second pilot port 136 fluidly connected to the boost port 138, thus providing excess flow Q acc =Q A -Q a flows from the second fluid line 128 to the second pilot port 136, to the boost port 138, then to the boost flow line 132 (through the casing or housing of the electric motor and pump), and then to the accumulator 102, thereby charging the accumulator 102.

[0069] In the four modes described above, the metering valve 146 may not be used (i.e., the metering valve 146 remains closed in an inactivated state). However, in some instances, it may be desirable to operate the hydraulic cylinder actuator 104 at a slow speed (e.g., extending or retracting the piston 108), but the pump and electric motor may be configured to operate at a minimum speed that may not be suitable for moving the piston 108 at such a slow speed. In such cases, the metering valve 146 can be used to throttle the fluid, thereby achieving a slow piston speed.

[0070] For example, if the piston 108 is extended against a resistive load at a slow speed, the electric motor may be operated at a minimum speed. The metering valve 146 is then actuated, thereby discharging a portion Q of the fluid flowing through the first fluid line 124. t flows through shuttle valve 144 to metering valve 146 and then to accumulator flow Q acc The metering valve 146 throttles the flow by controlling its opening (e.g., by controlling the amount of voltage or current provided to the solenoid 150 of the metering valve 146), thereby slowing the speed of the piston 108 to a desired speed.

[0071] To allow the auxiliary load to extend the piston 108, the electric motor may be stopped (i.e., the electric motor and pump are not commanded to provide flow). The fluid discharged at high pressure from the second chamber 118 flows through the second fluid line 128, and then a portion Q of such flow is t is provided through shuttle valve 144 to metering valve 146, which throttles the flow, thereby controlling the velocity of piston 108. Fluid flow Q t is the accumulator flow Q acc The combined fluid flows through the one-way shuttle valve 130 to the first fluid line 124 and then to the first chamber 116. Thus, no fluid is provided by the pump and the metering valve 146 controls the speed of the piston 108.

[0072] However, if it is desired to increase the speed of the piston 108 while the piston 108 is under an auxiliary load, the electric motor may be operated at its maximum speed, which provides a large amount of fluid flow to the first chamber 116 and causes the piston 108 to extend at a high speed.

[0073] The electric motor may be operated at a minimum speed to slowly retract the piston 108 against the resistive load. Thus, the pump provides fluid to the second fluid line 128, and a portion Q of such fluid t is provided through a shuttle valve 144 and then through a metering valve 146 which throttles the flow and then provides fluid to the boost flow line 132. t is combined with a portion of the fluid discharged from the first chamber 116, and this flow Q t flows through the reverse shuttle valve 130 to the boost flow line 132, after which the combined flow is acc to the accumulator, thereby charging the accumulator.

[0074] The electric motor may be stopped (i.e., the electric motor and pump are not commanded to provide flow) to allow the auxiliary load to retract the piston 108. The fluid flow Q discharged at high pressure from the first chamber 116 A flows through first fluid line 124 and then through shuttle valve 144 to metering valve 146, which throttles the flow, thereby controlling the velocity of piston 108. In this case, Q t =Q A and the fluid flow Q t is provided to boost flow line 132. Flow Q t Part Q acc Q acc and another portion Q a is provided through a one-way shuttle valve 130 to a second fluid line 128 and thereby to the second chamber 118 .

[0075] However, if it is desired to increase the retraction speed of the piston 108 while the piston 108 is under an auxiliary load, the electric motor may be operated at its maximum speed, which provides a large amount of fluid flow to the second chamber 118 and causes the piston 108 to retract at a high speed.

[0076] It may be desirable to integrate the components of the hydraulic system 100 into a self-contained electrohydraulic actuator (EHA) unit, where the hydraulic cylinder actuator 104, accumulator 102, various valves, and electrohydraulic power unit 120 are integrated into a single unit or assembly, thereby improving the power-to-volume ratio. This configuration eliminates the need for additional connections and hoses, which can improve the reliability of the hydraulic system 100.

[0077] Figure 2 shows a perspective view of an EHA 200 that integrates the electro-hydraulic power unit 120, accumulator 102, valves, and hydraulic cylinder actuator 104 of hydraulic system 100 into an assembly according to an exemplary configuration, Figure 3 shows a cross-sectional side view of EHA 200 according to an exemplary configuration, and Figure 4 shows a perspective cross-sectional view of EHA 200 according to an exemplary configuration. Figures 2 to 4 will be described together.

[0078] EHA 200 has a housing 202 that includes a first housing portion 204 (e.g., a rear housing cover) and a second housing portion 206 (e.g., a front housing cover) coupled to first housing portion 204. For example, first housing portion 204 may be threadedly engaged with second housing portion 206. First housing portion 204 and second housing portion 206 of housing 202 together define an enclosure within first housing portion 204 and second housing portion 206 in which electro-hydraulic power unit 120, valves of hydraulic system 100, hydraulic cylinder actuator 104, and accumulator 102 are disposed.

[0079] The first housing portion 204 is configured to house or contain the electro-hydraulic power unit 120, which includes an electric motor and pump assembly 205, as described below. The second housing portion 206 is configured to house or contain the hydraulic cylinder actuator 104, the accumulator 102, and a manifold 208 that integrates the valves of the hydraulic system 100.

[0080] For example, the hydraulic cylinder actuator 104 may include an end cap or gland 209, and the cylinder 106 of the hydraulic cylinder actuator 104 may be threaded into the gland 209, thereby mounting the hydraulic cylinder actuator 104 within the second housing portion 206. The gland 209 is generally annular and may have a seal attached to an inner surface of the gland 209, the seal being disposed around the rod 112 of the piston 108, thereby sealing the second chamber 118 and preventing fluid leakage into the environment surrounding the EHA 200. The cylinder 106 of the hydraulic cylinder actuator 104 is at least partially disposed within the second housing portion 206.

[0081] EHA 200 may also include a connector block 210 that fluidly connects electro-hydraulic power unit 120 to manifold 208. As shown in FIGS. 3-4 , connector block 210 is disposed partially within first housing portion 204 and partially within second housing portion 206, and is interposed between manifold 208 and assembly 205.

[0082] 2-4, the second housing portion 206 functions as a housing or outer wall of the accumulator 102. The accumulator 102 has an annular fluid chamber 212 that surrounds or encircles the cylinder 106 of the hydraulic cylinder actuator 104, such that the annular fluid chamber 212 is radially interposed or defined between the inner surface of the second housing portion 206 and the outer surface of the cylinder 106. With this configuration, the hydraulic cylinder actuator 104 is embedded within the accumulator 102. In other words, the annular fluid chamber 212 is defined between the outer circumferential surface of the cylinder 106 and the inner circumferential surface of the second housing portion 206.

[0083] The annular fluid chamber 212 is configured to contain a working fluid. The volume of the annular fluid chamber 212 is determined by the dimensions of the piston 108 (e.g., D H ,DR ) and the stroke (distance traveled by the piston 108) of the piston 108. The configuration and stroke of the piston 108 determine the volume of boost fluid that must flow into the first chamber 116 or the volume of excess fluid that is released from the first chamber 116, which in turn determines the volume of the annular fluid chamber 212.

[0084] 3-4, the accumulator 102 is configured as a piston-type accumulator that includes an annular gas chamber 214 that also surrounds or encircles the cylinder 106 of the hydraulic cylinder actuator 104. The annular gas chamber 214 is configured to contain the gas (e.g., nitrogen) of the accumulator 102. An accumulator gas valve 215 can be used to pre-fill the annular gas chamber 214 with gas.

[0085] The annular gas chamber 214 is separated and sealed from the annular fluid chamber 212 via an annular piston 216 of the accumulator 102. The annular piston 216 surrounds or encircles the cylinder 106 of the hydraulic cylinder actuator 104 and is slidably received in an annular space formed between the second housing portion 206 and the cylinder 106. The annular piston 216 may have one or more seals disposed in annular grooves formed in an outer surface of the annular piston 216, thereby sealing the annular gas chamber 214 from the annular fluid chamber 212.

[0086] As shown, the annular gas chamber 214 is axially interposed between the annular piston 216 and the accumulator head 217. The accumulator head 217 may have external threads that are configured to engage with internal threads on the second housing portion 206, thereby attaching the second housing portion 206 to the accumulator head 217.

[0087] During a fill phase of the accumulator 102, fluid is provided to the annular fluid chamber 212, causing the annular piston 216 to move distally (e.g., to the left in FIG. 3 ), compressing the gas in the annular gas chamber 214. During a discharge phase, the compressed gas pushes the annular piston 216 proximally (e.g., to the right in FIG. 3 ), expelling fluid from the annular fluid chamber 212 into the manifold 208.

[0088] In other examples, different types of accumulators may be used. For example, instead of the annular piston 216 and the annular gas chamber 214, a bladder or diaphragm may be used to store pressurized fluid in the annular fluid chamber 212 and facilitate the release of fluid from the annular fluid chamber 212.

[0089] 2-3 , the EHA 200 may include an external fluid line 218 (e.g., an external pipe) that may fluidly connect the manifold 208 to the second chamber 118 of the hydraulic cylinder actuator 104. For example, the external fluid line 218 may connect a port of the manifold 208 (described below with respect to FIG. 11 ) to a corresponding port of the accumulator head 217, which is fluidly connected to the second chamber 118 through a fluid passage between the accumulator head 217 and the cylinder 106. In other exemplary configurations, instead of using the external fluid line 218, a passage may be formed inside the housing 202 (e.g., in the second housing portion 206) that may fluidly connect the manifold 208 to the second chamber 118.

[0090] In one example, the manifold 208 includes an electrohydraulic valve (e.g., metering valve 146) therein. Such electrohydraulic valves are electrically actuated, for example, via a solenoid. In some solenoid valves, the solenoid coil is enclosed in a sealed housing that is pressurized or filled with a fluid, such as air or oil. When the solenoid coil is energized, this can generate heat, which can cause the fluid or air within the solenoid housing to expand. This expansion can create pressure that can affect the operation of the valve and potentially damage the solenoid coil. In this example, to provide air venting to the solenoid and prevent this problem, the housing 202 (e.g., second housing portion 206) can include one or more vent holes 220 formed in a circular array around the periphery of the housing 202. The vent holes 220 allow any excess pressure or fluid to escape. This venting maintains the solenoid coil at a safe operating temperature and ensures stable operation of the valve. Additionally, venting can also help prevent contamination of the fluid or gas controlled by the valve by preventing any fluid or gas from entering the solenoid housing.

[0091] Figure 5 shows a perspective view of first housing portion 204 and assembly 205 disposed within first housing portion 204 according to an exemplary configuration, and Figure 6 shows a cross-sectional side view of first housing portion 204 and assembly 205 disposed within first housing portion 204 according to an exemplary configuration. Figures 5 and 6 will be described together.

[0092] The first housing portion 204 may have a lug mount 300 having a hole 302. The lug mount 300 is configured as a protrusion that facilitates mounting the EHA 200 to a machine frame, for example, via a fastener placed through the hole 302. Other mounting configurations may also be used, such as a clevis, trunnion mount, flange mount, etc.

[0093] 6, the first housing portion 204 may have internal threads 304. The second housing portion 206 may have external threads configured to engage the internal threads 304, thereby enabling the second housing portion 206 to be coupled to the first housing portion 204.

[0094] Assembly 205 is disposed within an interior of first housing portion 204. Assembly 205 includes a pump motor casing 306 disposed or housed within first housing portion 204. First housing portion 204 and pump motor casing 306 define an interior 307 in which an electric motor 308 is integrated with a pump 310.

[0095] The pump 310 described herein is an internal gear pump as an illustrative example, however, other types of pumps may be used, such as a piston pump, a gerotor pump, an external gear pump, or a vane pump.

[0096] The electric motor 308 includes a stator 312 that is stationarily positioned within the interior chamber 307 of the pump motor casing 306. The stator 312 may have windings 314 that are wound around a body (e.g., a lamination stack) of the stator 312 and that generate a magnetic field when an electric current is provided to the windings 314. For example, as shown in FIG. 4 , the EHA 200 includes an electrical connector 222 that is attached to the first housing portion 204 and configured to connect to a power source (e.g., a battery or generator). The electrical connector 222 is also electrically connected to the windings 314, thereby providing power to the windings 314.

[0097] 6 , electric motor 308 further includes a rotor 316 positioned within stator 312. Electric motor 308 may further include magnets 318 attached to rotor 316 in the annular space between stator 312 and rotor 316. Magnets 318 are configured to interact with the magnetic field generated by windings 314 of stator 312, causing rotor 316 to rotate and generate torque. In other exemplary configurations, different types of electric motors that do not include permanent magnets may be used. Exemplary electric motor types that may be used include induction motors, surface mounted permanent magnet motors, interior permanent magnet motors, brushless DC motors, wound rotors, and switched reluctance motors.

[0098] Pump 310 is mounted at least partially within rotor 316 and stator 312 of electric motor 308. Pump 310 has a cylindrical protrusion 320 that is formed as part of pump motor casing 306 and extends axially or longitudinally within assembly 205. Pump 310 also includes a cylindrical protrusion 322 that is formed as part of first housing portion 204 and extends axially or longitudinally within assembly 205 toward cylindrical protrusion 320 of pump motor casing 306.

[0099] The cylindrical protrusions 320, 322 face each other and form a space between them, in which components of the pump 310 are disposed, so that the cylindrical protrusions 320, 322 are disposed to contain or sandwich the components of the pump 310. In this way, the cylindrical protrusions 320, 322 are configured as a pump housing 323.

[0100] Cylindrical protrusion 322 has an annular groove or recess that receives outer bushing 324. Cylindrical protrusion 320 may likewise have an annular groove or recess that receives another outer bushing similar to outer bushing 324.

[0101] Assembly 205 includes a drive flange 328, which is generally cylindrical in shape. Drive flange 328 is rotatably coupled to rotor 316 of electric motor 308 such that as rotor 316 rotates, drive flange 328 rotates with rotor 316. For example, drive flange 328 may be press fit within rotor 316. Alternatively, rotor 316 may be coupled to drive flange 328 using other configurations, such as a key-and-key configuration, a spline configuration, a self-retaining taper configuration, or the like.

[0102] Pump 310 also includes a ring gear 330, which is axially interposed between cylindrical projections 320, 322. Ring gear 330 has internal teeth formed on an inner circumferential surface thereof. In one example, ring gear 330 is integral with drive flange 328, such that ring gear 330 and drive flange 328 are formed as a single component. In another example, ring gear 330 may be a separate component that is coupled to drive flange 328 (e.g., via a key-and-keyway configuration, a spline configuration, a self-retaining taper configuration, etc.).

[0103] 6, an outer bushing 324 is radially interposed between the outer peripheral surface of cylindrical projection 322 and the inner peripheral surface of drive flange 328. Outer bushing 324 functions as a bearing that supports the rotation of drive flange 328 and ring gear 330 with minimal friction.

[0104] Pump 310 has a pump shaft 332 on which is mounted or integral a pump pinion 334 (e.g., a spur gear having external teeth formed on the outer periphery of pump shaft 332). The external teeth of pump pinion 334 engage internal teeth of ring gear 330. Furthermore, pump pinion 334 is mounted off-center relative to ring gear 330, i.e., the center of rotation of pump pinion 334 is eccentric or offset from the center of rotation of each of ring gears 330.

[0105] The cylindrical protrusion 320 has a cavity that receives the pump shaft 332, and a first inner bushing 336 is radially interposed between the outer circumferential surface of the pump shaft 332 and the inner circumferential surface of the cylindrical protrusion 320. Similarly, the cylindrical protrusion 322 has a hole or cavity that receives the other end of the pump shaft 332, and a second inner bushing 338 is radially interposed between the outer circumferential surface of the pump shaft 332 and the inner circumferential surface of the cylindrical protrusion 322.

[0106] The inner bushings 336, 338 function as bearings that support the rotation of the pump shaft 332 with minimal friction. Because the pump shaft 332 is off-center from the ring gear 330, the inner bushings 336, 338 (which support the pump shaft 332) are off-center relative to the outer bushing 324 (which supports the drive flange 328).

[0107] The ring gear 330 and the pump pinion 334 are supported axially inward via a thrust plate 340 disposed on one side of the ring gear 330 and the pump pinion 334. Thus, the pump pinion 334 and the ring gear 330 are interposed or sandwiched between the thrust plate 340 and the cylindrical protrusion 322.

[0108] Furthermore, the thrust plate 340 is supported by the cylindrical protrusion 320. In particular, the thrust plate 340 is in contact with the cylindrical protrusion 320. The thrust plate 340 is configured as a floating component that can move axially to compensate for axial clearance and reduce internal leakage within the pump 310.

[0109] 5, the pump 310 has a first pump port 342 (e.g., representing the first pump port 122) and a second pump port 344 (e.g., representing the second pump port 126). The pump 310 may be configured to operate as a bidirectional pump. In particular, the first pump port 342 may function as an inlet port configured to receive fluid from the hydraulic cylinder actuator 104, and the second pump port 344 may function as an outlet or discharge port for providing fluid discharged from the pump 310 to the hydraulic cylinder actuator 104. In this mode of operation, the pump pinion 334 and the ring gear 330 rotate in a first rotational direction, and the piston 108 may move in a first direction.

[0110] In another mode of operation, the first pump port 342 can function as a discharge port for providing fluid discharged from the pump 310 to the hydraulic cylinder actuator 104, and the second pump port 344 can function as an inlet port configured to receive fluid from the hydraulic cylinder actuator 104. In this mode of operation, the pump pinion 334 and ring gear 330 rotate in a second rotational direction opposite the first rotational direction, and the piston 108 can move in the second direction opposite the first direction.

[0111] Additionally, the pump 310 can operate in pump mode or motor mode. In pump mode, the pump 310 provides pressurized fluid to the hydraulic cylinder actuator 104, which drives the piston 108 against a resistive load. In motor mode, the fluid returned from the hydraulic cylinder actuator 104 is high-pressure fluid, which can drive the pump 310 and electric motor 308 in a regenerative mode.

[0112] In one example, the assembly 205 may further include a first cooling port 346 and a second cooling port 348. The fluid provided by the accumulator 102 (when the accumulator 102 is in a discharge mode) may first flow through one of the cooling ports 346, 348 to the interior chamber 307, thereby cooling the electric motor 308, and then flow from the other of the cooling ports 346, 348 to the hydraulic cylinder actuator 104.

[0113] Similarly, fluid returning from the hydraulic cylinder actuator 104 to the accumulator 102 (when the accumulator 102 is in a charging mode) may first flow through one of the cooling ports 346, 348 to the interior chamber 307, thereby cooling the electric motor 308, and then flow through the other of the cooling ports 346, 348 to the accumulator 102. As described in more detail below, the connector block 210 shown in Figures 3-4 includes ports corresponding to the pump ports 342, 344 and the cooling ports 346, 348, respectively, to facilitate directing or routing fluid flow to and from the electric motor 308 and pump 310 assembly 205.

[0114] The operation of pump 310 will now be described assuming that pump 310 rotates in a given direction, however, it should be understood that pump 310 can also operate in the reverse direction by reversing the operation of the ports and fluid volumes.

[0115] During operation, rotor 316 of electric motor 308 drives ring gear 330 via drive flange 328, causing ring gear 330 to rotate, which in turn causes pump pinion 334 to rotate with ring gear 330. As previously mentioned, pump pinion 334 rotates off-center relative to ring gear 330. In other words, the longitudinal axis about which pump pinion 334 rotates is offset from the respective longitudinal axis about which ring gear 330 rotates.

[0116] When the external teeth of the pump pinion 334 and the internal teeth of the ring gear 330 separate or disengage, the external teeth of the pump pinion 334 and the internal teeth of the ring gear 330 create an expansion volume (i.e., an expansion chamber). This expansion volume collectively refers to the pockets formed between the separated teeth. This expansion volume functions as a suction void formed between the separated teeth on the suction side of the pump 310, and this suction void is fluidly connected to an inlet port (e.g., first pump port 342). Thus, fluid from the inlet port fills the expansion volume between the teeth.

[0117] The fluid is then conveyed by the external teeth of pump pinion 334 and the internal teeth of ring gear 330 to another chamber or volume on the discharge side of pump 310, which is fluidly connected to a discharge port (e.g., second pump port 344). The meshing of the teeth of pump pinion 334 with the teeth of ring gear 330 displaces the fluid, which is then provided to the discharge port. Thus, as the teeth of pump pinion 334 and the teeth of ring gear 330 interlock on the discharge side of pump 310, the volume decreases and fluid is forced out under pressure.

[0118] When the external teeth of pump pinion 334 mesh with the internal teeth of ring gear 330, they form a seal between the expansion volume having low pressure fluid received from the inlet port and the volume between the meshing or about to mesh teeth at the outlet port. The seal created by the meshing teeth forces fluid out the discharge port and prevents fluid from flowing back toward the inlet port.

[0119] 6, pump 310 includes a crescent seal assembly including an inner crescent portion 350 and an upper or outer crescent portion 352. The terms "inner" and "outer" refer to the radial positioning of the crescent portions, where inner crescent portion 350 is disposed radially inward relative to outer crescent portion 352.

[0120] Inner crescent 350 and outer crescent 352 are axially supported within the interior space between ring gear 330 and pump pinion 334 by pivot or locating pins 354. Referring to Figure 6, locating pins 354 are partially disposed in blind holes formed in cylindrical projections 320, 322 and extend through locating pin through holes in thrust plate 340 and crescents 350, 352.

[0121] With this configuration, inner crescent portion 350 and outer crescent portion 352 are held axially in place by locating pin 354, which also maintains the orientation of crescent portions 350, 352. Thus, locating pin 354 axially supports the crescent seal assembly (inner crescent portion 350 and outer crescent portion 352).

[0122] As the pump pinion 334 and ring gear 330 rotate during operation of the pump 310, the crescents 350, 352 divide the fluid as it is conveyed from the low-pressure intake expansion volume to the volume connected to the discharge port, thus forming a seal between the low-pressure volume and the high-pressure volume.

[0123] In particular, the outer surface (i.e., the radially outer surface) of outer crescent 352 abuts and creates a seal with the internal teeth of ring gear 330. An effective seal between the outer surface of outer crescent 352 and the internal teeth of ring gear 330 prevents leakage from the high-pressure volume to the low-pressure volume. As used herein, the terms "block" or "obstruct" fluid flow mean substantially preventing fluid flow, for example, except at a minimum rate of drops per minute.

[0124] Similarly, the inner surface (i.e., the radially inner surface) of inner crescent 350 abuts and creates a seal against the external teeth of pump pinion 334. An effective seal between the inner surface of inner crescent 350 and the external teeth of pump pinion 334 prevents leakage from the high pressure volume to the low pressure volume.

[0125] As described above, connector block 210 of EHA 200 fluidly connects assembly 205 (electric motor 308 and pump 310) to manifold 208. Thus, connector block 210 is configured to conduct fluid between pump ports 342, 344 (e.g., inlet and outlet ports) of pump 310 and manifold 208, and is also configured to conduct cooling fluid (e.g., fluid provided by or to accumulator 102) between assembly 205 and manifold 208 (which is fluidly connected to annular fluid chamber 212 of accumulator 102).

[0126] Figure 7 shows a partial cross-sectional view of EHA 200 showing connector block 210 attached to manifold 208 according to an exemplary configuration, and Figure 8 shows a rear view of connector block 210 according to an exemplary configuration. Figure 7 does not show assembly 205, thereby revealing details of connector block 210. Figure 8 shows the rear or proximal end of connector block 210, which abuts assembly 205 disposed within first housing portion 204.

[0127] Connector block 210 includes a first port 400 that is aligned with and in fluid communication with first pump port 342, and connector block 210 includes a second port 402 that is aligned with and in fluid communication with second pump port 344. Additionally, connector block 210 may include a first cooling port 404 that is aligned with and in fluid communication with first cooling port 346 of assembly 205. First cooling port 404 may, for example, fluidly connect reverse shuttle valve 130 (disposed within manifold 208) to internal chamber 307 of assembly 205. Such a connection between reverse shuttle valve 130 and first cooling port 404 represents boost flow line 132, for example, as described above with respect to FIG. 1 .

[0128] The connector block 210 may also include a second cooling port 406 that is aligned with and in fluid communication with the second cooling port 348 of the assembly 205. The second cooling port 406 may, for example, fluidly connect the annular fluid chamber of the accumulator 102 to the internal chamber 307 of the assembly 205.

[0129] Manifold 208 integrates the various valves of hydraulic system 100. Manifold 208 is configured to provide fluid to and receive fluid from hydraulic cylinder actuators 104 and accumulators 102, and is also configured to provide fluid to and receive fluid from assembly 205 via connector block 210.

[0130] FIG. 9 shows a partial cross-sectional view of EHA 200 showing manifold 208 according to an exemplary configuration, FIG. 10 shows a rear view of manifold 208 according to an exemplary configuration, and FIG. 11 shows a side view of manifold 208 according to an exemplary configuration. FIG. 9 does not show assembly 205 or connector block 210, thereby revealing details of manifold 208. FIG. 10 shows the rear or proximal end of connector block 210, which mates with connector block 210. Manifold 208 may have external threads that engage with internal threads on second housing portion 206, thereby mounting manifold 208 within second housing portion 206.

[0131] The manifold 208 includes cavities in which the valves of the hydraulic system 100 are mounted and includes fluid passages connecting the cavities. The manifold 208 also includes ports and fluid passages that route fluid between the hydraulic cylinder actuators 104 and accumulators 102 on one side of the manifold 208 and a connector block 210 (fluidly connected to assembly 205) on the other side of the manifold 208.

[0132] 10 , manifold 208 includes a first manifold port 500 and a second manifold port 502 that are aligned and in fluid communication with ports 400, 402 of connector block 210 (which are fluidly connected to pump ports 342, 344 of assembly 205). Manifold 208 also includes a first manifold cooling port 504 that may be in fluid communication from accumulator 102 to interior chamber 307 of assembly 205, thereby cooling electric motor 308. The manifold 208 also includes a second manifold cooling port 506 which may communicate fluid communicated from the accumulator 102 to the internal chamber 307 back from the internal chamber 307 to the reverse shuttle valve 130, which is located within a cavity 508 shown in the side of the manifold 208 in FIG. 11.

[0133] 10, the manifold 208 further includes a cavity 510 that houses the pressure relief valve 148 of the hydraulic system 100, and the manifold 208 further includes a cavity 512 that houses the shuttle valve 144 of the hydraulic system 100. The manifold 208 further includes a cavity 514 that houses the metering valve 146 of the hydraulic system 100.

[0134] The manifold 208 receives fluid from and provides fluid to the chambers 116, 118 of the hydraulic cylinder actuator 104. Referring to FIG. 11 , the manifold includes a rod-side chamber port 516 that is fluidly connected to the second chamber 118 of the hydraulic cylinder actuator 104 via an external fluid line 218 shown in FIGS. 2-3. FIG. 11 also shows that the manifold 208 includes a first annular groove 518 and a second annular groove 520, in which a seal (e.g., an O-ring) may be disposed, respectively, to seal the manifold 208 against the inner surface of the second housing portion 206.

[0135] 12 illustrates a front view of the manifold 208 in an exemplary configuration. As shown, the manifold 208 includes an accumulator port 522 that is fluidly connected to the annular fluid chamber 212 of the accumulator 102. This configuration allows the accumulator port 522 to communicate fluid to and from the annular fluid chamber 212 of the accumulator 102. The manifold 208 also includes a head-side chamber port 524 that is fluidly connected to the first chamber 116 of the hydraulic cylinder actuator 104.

[0136] As an example of how fluid is routed through EHA 200, during retraction of piston 108, fluid is expelled from first chamber 116 and then flows through head-side chamber port 524 of manifold 208. A portion of the fluid flows through second manifold port 502, through second port 402 of connector block 210, and to second pump port 344.

[0137] Another portion of the fluid flows to the one-way shuttle valve 130, then through the second manifold cooling port 506, through the second cooling port 406 in the connector block 210, through the second cooling port 348 in the assembly 205, and into the interior chamber 307 of the assembly 205, thereby cooling the electric motor 308. The fluid then flows from the interior chamber 307 through the first cooling port 346 in the assembly 205, through the first cooling port 404 in the connector block 210, back to the first manifold cooling port 504, through the accumulator port 522, and then back into the annular fluid chamber 212 of the accumulator 102, thereby filling the accumulator 102.

[0138] Fluid from the first pump port 342 is provided to the first port 400 of the connector block 210 and then through the rod side chamber port 516 of the manifold 208. The fluid is then provided to the second chamber 118 of the hydraulic cylinder actuator 104 via the external fluid line 218 shown in Figures 2-3.

[0139] This fluid flow path may be reversed upon extension of the piston 108 .

[0140] The configuration of EHA 200 may offer several advantages. Accumulator 102 is integrated within housing 202 of EHA 200, which surrounds cylinder 106 of hydraulic cylinder actuator 104. This configuration reduces the overall size and length of EHA 200 compared to conventional EHAs in which the accumulator is a separate element mounted adjacent to the hydraulic cylinder and communicates with the hydraulic cylinder via a fluid line.

[0141] Furthermore, the configuration of EHA 200, in which manifold 208, electro-hydraulic power unit 120 (e.g., electric motor 308 and pump 310 assembly 205), hydraulic cylinder actuator 104, and accumulator 102 are integrated into a single housing (e.g., housing 202), reduces the number of connections (fluid lines, fittings, couplings, etc.), thereby improving the reliability of EHA 200.

[0142] Also, as previously mentioned, because accumulator 102 provides low pressure fluid, and therefore the walls of second housing portion 206 do not need to withstand high pressures, the walls do not need to be thick. However, by embedding accumulator 102 within housing 202, accumulator 102 is protected from debris or impacts to which EHA 200 may be exposed.

[0143] Additionally, by integrating the valves of EHA 200 into manifold 208, which is also embedded within housing 202, the valves are protected from debris, shocks, or impacts to which EHA 200 may be exposed.

[0144] 13 is a flowchart of a method 600 for assembling EHA 200 according to an example configuration. Method 600 may include one or more operations, functions, or acts, as illustrated by one or more of steps 602-614.

[0145] While steps are illustrated sequentially, these steps may be performed in parallel and / or in a different order than described herein. Also, various steps may be combined into fewer steps, divided into additional steps, and / or eliminated based on the desired configuration. Of course, for these and other processes and methods disclosed herein, the flowcharts illustrate the functionality and operation of one possible configuration of the examples. Included within the scope of the examples of the present disclosure are alternative configurations in which functions may be performed in a different order than illustrated or discussed, for example, substantially concurrently or in reverse order, depending on the functionality involved, as would be apparent to one of ordinary skill in the art.

[0146] At block 602 , the method 600 includes attaching the electric motor 308 and pump 310 assembly 205 to the first housing portion 204 .

[0147] At block 604, the method 600 includes providing a piston 108, including a rod 112, a piston head 110, and a gland 209, of a hydraulic cylinder actuator 104. As used herein, the term "providing" includes any act, for example, with respect to a piston 108 or other component, to make the piston 108 or other component usable, such as bringing the piston 108 or other component into an apparatus or work environment for further processing (e.g., installation of other components, etc.).

[0148] As an example, in block 604, the method 600 may include providing a rod 112 with a gland 209 attached, then attaching a piston head 110 to the rod 112, and then locking the piston head 110 to the rod 112 using a nut.

[0149] At block 606, the method 600 includes coupling the cylinder 106 of the hydraulic cylinder actuator 104 to the gland 209 such that the piston head 110 is slidably received within the cylinder 106. For example, the gland 209 may have external threads and the cylinder 106 may have corresponding internal threads, allowing the cylinder 106 to be threadedly engaged with the gland 209.

[0150] At block 608 , the method 600 includes mounting the accumulator head 217 around the cylinder 106 .

[0151] At block 610, the method 600 includes coupling the second housing portion 206 to the accumulator head 217 such that an annular space is formed between the second housing portion 206 and the cylinder 106 of the hydraulic cylinder actuator 104. For example, the accumulator head 217 may include external threads and the second housing portion 206 may have corresponding internal threads, allowing the second housing portion 206 to be threadedly coupled to the accumulator head 217.

[0152] At block 612 , the method 600 includes inserting the annular piston 216 of the accumulator 102 into the annular space such that the annular piston 216 divides the annular space into an annular fluid chamber 212 and an annular gas chamber 214 .

[0153] At block 614, the method 600 includes coupling the first housing portion 204, having the assembly 205 disposed therein, to the second housing portion 206. For example, the first housing portion 204 may have internal threads 304, and the second housing portion 206 may have external threads configured to engage with the internal threads 304, thereby coupling the second housing portion 206 to the first housing portion 204.

[0154] Method 600 may further include other steps for assembling EHA 200, as described throughout this specification.

[0155] In the above detailed description, various features and operations of the disclosed system are explained with reference to the accompanying drawings. The exemplary configurations described herein are not meant to be limiting. Particular aspects of the disclosed system may be arranged and combined in a wide variety of configurations, all of which are contemplated herein.

[0156] Furthermore, unless the context suggests otherwise, features shown in each drawing may be used in combination with one another. Thus, it should be understood that the drawings should generally be viewed as component aspects of one or more overall configurations, and that not all illustrated features are required for each configuration.

[0157] Furthermore, any listing of elements, blocks, or steps in the specification or claims is for the purpose of clarity, and therefore, such listing should not be construed as requiring or implying that these elements, blocks, or steps be adhered to in a particular arrangement or performed in a particular order.

[0158] Furthermore, a device or system may be used or configured to perform the functions presented in the figures. In some cases, components of the device and / or system may be configured to perform the functions, whereby the components are in fact configured and organized (with hardware and / or software) to enable such performance. In other examples, components of the device and / or system may be adapted to perform a function, enable performance of a function, or be arranged so as to be suitable for performing a function, e.g., when operated in a particular manner.

[0159] The term "substantially" or "about" means that the recited characteristic, parameter or numerical value need not be achieved exactly, but deviations or variations including, for example, tolerances, measurement errors, measurement accuracy limits and other factors known to those skilled in the art may occur to an extent that does not prevent the effect that the characteristic is intended to provide.

[0160] The arrangements described herein are for illustrative purposes only. Thus, those skilled in the art will recognize that other arrangements and other elements (e.g., machines, interfaces, operations, sequences, and groupings of operations) may be substituted, and that some elements may be omitted entirely, depending on the desired results. Furthermore, many of the described elements are functional entities that may be configured as separate or distributed components or in any suitable combination and location with other components.

[0161] While various embodiments and configurations have been disclosed herein, other embodiments and configurations will be apparent to those skilled in the art. The various embodiments and configurations disclosed herein are for illustrative purposes only and are not intended to be limiting, with the true scope being indicated by the following claims, along with the full scope of equivalents to which such claims are entitled. Additionally, the terminology used herein is for the purpose of describing particular configurations only and is not intended to be limiting.

[0162] Accordingly, embodiments of the present disclosure may relate to one of the following listed exemplary embodiments (EEE):

[0163] EEE1 is an electro-hydraulic actuator including a housing; a hydraulic cylinder actuator disposed within the housing and including a cylinder and a piston, the piston dividing an interior space of the cylinder into a first chamber and a second chamber, the hydraulic cylinder actuator being unbalanced such that a first fluid flow rate of fluid provided to either the first chamber or the second chamber to drive the piston in a predetermined direction is different from a second fluid flow rate of fluid discharged from the other chamber as the piston moves; and an annular fluid chamber disposed within the housing and surrounding the cylinder of the hydraulic cylinder actuator. an accumulator configured to provide a boost fluid flow from or receive an excess fluid flow into an annular fluid chamber, the boost fluid flow or the excess fluid flow comprising a difference between a first fluid flow rate and a second fluid flow rate; and an assembly disposed within the housing, the assembly comprising: (i) a pump configured to provide a bidirectional fluid flow source; and (ii) an electric motor configured to drive the pump in opposite rotational directions to provide fluid flow to a first chamber or a second chamber of the hydraulic cylinder actuator, thereby driving a piston.

[0164] EEE2 is the electro-hydraulic actuator of EEE1, wherein the accumulator further comprises an annular piston disposed around the cylinder of the hydraulic cylinder actuator, the annular piston being slidably received in an annular space formed between a housing and the cylinder of the hydraulic cylinder actuator, and an annular gas chamber surrounding the cylinder, the annular piston separating the annular fluid chamber from the annular gas chamber.

[0165] EEE3 is the electro-hydraulic actuator according to EEE1 or EEE2, wherein the assembly comprises an internal chamber in which the electric motor and the pump are disposed, and wherein a boost fluid flow provided from the annular fluid chamber of the accumulator flows through the internal chamber to cool the electric motor before flowing to the hydraulic cylinder actuator, and wherein a surplus fluid flow from the hydraulic cylinder actuator flows through the internal chamber to cool the electric motor before flowing to the annular fluid chamber of the accumulator.

[0166] EEE4 is the electro-hydraulic actuator of any one of EEE1 to EEE3, wherein the accumulator further comprises an accumulator head having external threads, and the housing comprises internal threads that engage with the external threads of the accumulator head to attach the housing to the accumulator head.

[0167] EEE5 is an electro-hydraulic actuator according to any one of EEE1 to EEE4, wherein the housing comprises a first housing portion in which an electric motor and pump assembly is arranged, and a second housing portion coupled to the first housing portion, the second housing portion comprising an accumulator and a hydraulic cylinder actuator, whereby the cylinder of the hydraulic cylinder actuator is arranged within the second housing portion and the accumulator is arranged in the annular space between the cylinder and the second housing portion.

[0168] EEE6 is the electro-hydraulic actuator of any one of EEE1 to EEE5, wherein the electric motor comprises (i) a stator fixedly positioned in the housing, and (ii) a rotor positioned within the stator and rotatable relative to the stator, and the pump is a gear pump positioned at least partially within the rotor of the electric motor, the gear pump comprising: (i) a drive flange rotatably coupled to the rotor of the electric motor, (ii) a ring gear coupled to the drive flange and configured to rotate with the drive flange, (iii) a pump pinion disposed within the ring gear, the external teeth of the pump pinion engaging the internal teeth of the ring gear, and (iv) a plurality of ports comprising a first pump port and a second pump port, wherein when the rotor rotates, the drive flange and ring gear rotate with the rotor, thereby rotating the pump pinion within the ring gear, thereby drawing fluid in through the first pump port and displacing fluid to the second pump port for discharge.

[0169] EEE7 is the electro-hydraulic actuator described in EEE6, further comprising a pump motor casing having a first cylindrical protrusion, the housing having a second cylindrical protrusion facing the first cylindrical protrusion, whereby the ring gear and pump pinion are interposed between the first cylindrical protrusion and the second cylindrical protrusion.

[0170] EEE8 is the electro-hydraulic actuator of any one of EEE1 to EEE7, further comprising a manifold disposed within the housing and fluidly connected to the pump, the accumulator, and the hydraulic cylinder actuator, the manifold having a plurality of ports, cavities configured to accommodate respective valves therein, and fluid passages.

[0171] EEE9 is an electro-hydraulic actuator as described in EEE8, wherein the manifold has a head side chamber port fluidly connected to a first chamber of the hydraulic cylinder actuator and a rod side chamber port fluidly connected to a second chamber of the hydraulic cylinder actuator.

[0172] EEE10 is the electrohydraulic actuator of EEE9, wherein the rod side chamber port is fluidly connected to the second chamber via an external fluid line located outside the housing.

[0173] EEE11 is the electrohydraulic actuator of any one of EEE8 to 10, wherein the manifold comprises an accumulator port fluidly connected to an annular fluid chamber of the accumulator.

[0174] EEE12 is the electro-hydraulic actuator of any one of EEE8 to 11, wherein the pump comprises a first pump port and a second pump port, the pump configured to draw fluid through the first pump port and push fluid to the second pump port for discharge, and the manifold further comprises a first manifold port fluidly connected to the first pump port and a second manifold port fluidly connected to the second pump port.

[0175] EEE13 is the electro-hydraulic actuator of EEE12, wherein the assembly comprises a first cooling port and a second cooling port, the first cooling port and the second cooling port being fluidly connected to an internal chamber of the assembly in which the electric motor is disposed, and the manifold comprises a first manifold cooling port fluidly connected to the first cooling port of the assembly and a second manifold cooling port fluidly connected to the second cooling port of the assembly, wherein a boost fluid flow provided from the annular fluid chamber of the accumulator flows through the first manifold cooling port to the first cooling port of the assembly, then through the internal chamber to cool the electric motor before being discharged from the internal chamber through the second cooling port of the assembly to the second manifold cooling port.

[0176] EEE14 is the electrohydraulic actuator of EEE13, further comprising a connector block interposed between the manifold and the assembly, the connector block configured to fluidly connect the assembly to the manifold.

[0177] EEE15 is the electro-hydraulic actuator described in EEE14, wherein the connector block has a first port fluidly connected to the first pump port and the first manifold port, a second port fluidly connected to the second pump port and the second manifold port, a first cooling port fluidly connected to the first cooling port and the first manifold cooling port of the assembly, and a second cooling port fluidly connected to the second cooling port and the second manifold cooling port of the assembly.

[0178] EEE16 is the electro-hydraulic actuator of any one of EEE8 to 15, wherein the manifold comprises at least one valve that is electronically actuated via a solenoid, and wherein the housing comprises one or more vent holes that allow expanded air caused by operation of the solenoid to be vented to the surrounding environment of the housing.

[0179] EEE17 is the electro-hydraulic actuator of any one of EEE8 to 16, wherein the manifold comprises at least one annular groove in which a seal is disposed to seal the manifold against the inner surface of the housing.

[0180] EEE18 is a method for assembling an electro-hydraulic actuator according to any one of EEE1 to 17. The method includes mounting an electric motor and pump assembly within a first housing part, providing a hydraulic cylinder actuator piston having a rod, a piston head, and a gland, coupling a cylinder of the hydraulic cylinder actuator to the gland such that the piston head is slidably received within the cylinder, mounting an accumulator head around the cylinder, coupling the second housing part to the accumulator head such that an annular space is formed between the second housing part and the cylinder of the hydraulic cylinder actuator, inserting the accumulator annular piston into the annular space such that the annular piston divides the annular space into an annular fluid chamber and an annular gas chamber, and coupling the first housing part with the assembly disposed therein to the second housing part.

[0181] EEE19 is the method of EEE18, further including attaching a manifold to the second housing portion to fluidly connect the annular fluid chamber of the accumulator and the hydraulic cylinder actuator, and attaching a connector block to the manifold, followed by coupling the first housing portion to the second housing portion.

[0182] EEE20 is the method described in EEE19, wherein the piston head divides the interior space of the cylinder into a first chamber and a second chamber, and further comprising attaching an external pipe to the second housing portion to fluidly connect the second chamber to the manifold.

Claims

1. 1. An electrohydraulic actuator comprising: Housing and a hydraulic cylinder actuator disposed within the housing, the hydraulic cylinder actuator comprising a cylinder and a piston, the piston dividing an interior space of the cylinder into a first chamber and a second chamber, the hydraulic cylinder actuator being unbalanced such that a first fluid flow rate of fluid provided to the first chamber or the second chamber to drive the piston in a predetermined direction is different from a second fluid flow rate of fluid discharged from the other chamber as the piston moves; an accumulator disposed within the housing and including an annular fluid chamber surrounding the cylinder of the hydraulic cylinder actuator, the accumulator configured to provide a boost fluid flow from the annular fluid chamber or to receive an excess fluid flow into the annular fluid chamber, the boost fluid flow or the excess fluid flow comprising a difference between the first fluid flow rate and the second fluid flow rate; an assembly disposed within the housing, the assembly comprising: (i) a pump configured to provide a bidirectional fluid flow source; and (ii) an electric motor configured to drive the pump in opposite rotational directions, thereby driving the piston, to provide fluid flow to either the first chamber or the second chamber of the hydraulic cylinder actuator; 1. An electrohydraulic actuator comprising:

2. The accumulator comprises: an annular piston disposed around the cylinder of the hydraulic cylinder actuator, the annular piston being slidably received in an annular space formed between the housing and the cylinder of the hydraulic cylinder actuator; an annular gas chamber surrounding the cylinder, the annular piston separating the annular fluid chamber from the annular gas chamber; The electrohydraulic actuator of claim 1 further comprising:

3. 2. The electro-hydraulic actuator of claim 1, wherein the assembly includes an internal chamber in which the electric motor and the pump are disposed, the boost fluid flow provided from the annular fluid chamber of the accumulator passing through the internal chamber to cool the electric motor before flowing to the hydraulic cylinder actuator, and the excess fluid flow from the hydraulic cylinder actuator passing through the internal chamber to cool the electric motor before flowing to the annular fluid chamber of the accumulator.

4. 2. The electro-hydraulic actuator of claim 1, wherein the accumulator further comprises an accumulator head having external threads, and the housing comprises internal threads that engage the external threads of the accumulator head to attach the housing to the accumulator head.

5. The housing includes: a first housing portion in which the electric motor and pump assembly is disposed; a second housing portion coupled to the first housing portion, the second housing portion comprising the accumulator and the hydraulic cylinder actuator, whereby the cylinder of the hydraulic cylinder actuator is disposed within the second housing portion and the accumulator is disposed in an annular space between the cylinder and the second housing portion; The electrohydraulic actuator of claim 1 , comprising:

6. 2. The electro-hydraulic actuator of claim 1, wherein the electric motor comprises: (i) a stator fixedly positioned in the housing; and (ii) a rotor positioned within the stator and rotatable relative to the stator; the pump is a gear pump positioned at least partially within the rotor of the electric motor; the gear pump comprising: (i) a drive flange rotatably coupled to the rotor of the electric motor; (ii) a ring gear coupled to the drive flange and configured to rotate therewith; (iii) a pump pinion disposed within the ring gear, external teeth of the pump pinion engaging internal teeth of the ring gear; and (iv) a plurality of ports comprising a first pump port and a second pump port; wherein rotation of the rotor causes the drive flange and the ring gear to rotate with the rotor, thereby rotating the pump pinion within the ring gear, thereby drawing fluid through the first pump port and displacing fluid to the second pump port for discharge.

7. 7. The electro-hydraulic actuator of claim 6, further comprising a pump motor casing including a first cylindrical protrusion, said housing including a second cylindrical protrusion facing said first cylindrical protrusion, whereby said ring gear and said pump pinion are interposed between said first cylindrical protrusion and said second cylindrical protrusion.

8. 10. The electro-hydraulic actuator of claim 1, further comprising a manifold disposed within the housing and fluidly connected to the pump, the accumulator, and the hydraulic cylinder actuator, the manifold comprising a plurality of ports, cavities configured to accommodate respective valves therein, and fluid passages.

9. The manifold comprises: a head-side chamber port fluidly connected to the first chamber of the hydraulic cylinder actuator; a rod-side chamber port fluidly connected to the second chamber of the hydraulic cylinder actuator; The electrohydraulic actuator of claim 8 , comprising:

10. The electrohydraulic actuator of claim 9 , wherein the rod side chamber port is fluidly connected to the second chamber via an external fluid line located outside the housing.

11. The electrohydraulic actuator of claim 8 , wherein the manifold includes an accumulator port fluidly connected to the annular fluid chamber of the accumulator.

12. the pump comprises a first pump port and a second pump port, the pump configured to draw fluid through the first pump port and displace the fluid to the second pump port for expulsion; The manifold comprises: a first manifold port fluidly connected to the first pump port; a second manifold port fluidly connected to the second pump port; The electrohydraulic actuator of claim 8 further comprising:

13. the assembly includes a first cooling port and a second cooling port, the first cooling port and the second cooling port being in fluid communication with an interior chamber of the assembly in which the electric motor is disposed; The manifold comprises: a first manifold cooling port fluidly connected to the first cooling port of the assembly; a second manifold cooling port fluidly connected to the second cooling port of the assembly, wherein the boost fluid flow provided from the annular fluid chamber of the accumulator flows through the first manifold cooling port to the first cooling port of the assembly, then through the inner chamber to cool the electric motor, and then discharged from the inner chamber through the second cooling port of the assembly to the second manifold cooling port; The electrohydraulic actuator of claim 12 , comprising:

14. The electrohydraulic actuator of claim 13 , further comprising a connector block interposed between the manifold and the assembly, the connector block configured to fluidly connect the assembly to the manifold.

15. The connector block comprises: a first port fluidly connected to the first pump port and the first manifold port; a second port fluidly connected to the second pump port and the second manifold port; a first cooling port fluidly connected to the first cooling port of the assembly and the first manifold cooling port; a second cooling port fluidly connected to the second cooling port of the assembly and the second manifold cooling port; The electrohydraulic actuator of claim 14 comprising:

16. 9. The electro-hydraulic actuator of claim 8, wherein the manifold includes at least one valve that is electronically actuated via a solenoid, and the housing includes one or more vent holes that allow expanded air resulting from operation of the solenoid to be vented to the environment surrounding the housing.

17. The electrohydraulic actuator of claim 8 , wherein the manifold includes at least one annular groove having a seal disposed therein to seal the manifold against the inner surface of the housing.

18. 1. A method for assembling an electrohydraulic actuator, comprising: Mounting an electric motor and pump assembly within the first housing portion; providing a piston of a hydraulic cylinder actuator, the piston comprising a rod, a piston head and a gland; coupling a cylinder of the hydraulic cylinder actuator to the gland such that the piston head is slidably received within the cylinder; mounting an accumulator head around the cylinder; coupling a second housing portion to the accumulator head such that an annular space is formed between the second housing portion and the cylinder of the hydraulic cylinder actuator; inserting an annular piston of an accumulator into the annular space such that the annular piston divides the annular space into an annular fluid chamber and an annular gas chamber; coupling the first housing portion with the assembly disposed therein to the second housing portion; A method comprising:

19. mounting a manifold on the second housing portion to fluidly connect the annular fluid chamber of the accumulator and the hydraulic cylinder actuator; attaching a connector block to the manifold prior to coupling the first housing portion to the second housing portion; 20. The method of claim 18, further comprising:

20. The piston head divides the internal space of the cylinder into a first chamber and a second chamber, 20. The method of claim 19, further comprising attaching an external pipe to the second housing portion to fluidly connect the second chamber to the manifold.

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