Miniature hydraulic valves and their application to robotic systems.

Abstract

The electrohydraulic valve includes a valve housing having a common chamber and a metering port in communication with the common chamber. The valve housing is coupled to a valve manifold having a supply port and an exhaust port. A first nozzle in fluid communication with the supply port has a first orifice. A second nozzle in fluid communication with the exhaust port has a second orifice. The first valve disposed in the common chamber is operable to move between a closed position in which the first valve closes the first orifice and an open position in which the first valve opens the first orifice. The second valve disposed in the common chamber is operable to move between a closed position in which the second valve closes the second orifice and an open position in which the second valve opens the second orifice.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 63 / 428997, filed November 30, 2022, the contents of which are incorporated herein by reference.

[0002] The present systems, devices, and methods relate generally to hydraulic valves, and more particularly to miniature hydraulic valves for hydraulically actuated robotic components. [Background technology]

[0003] A robot is a machine that can assist or replace humans in performing tasks. Robots can be used in a variety of applications, including construction, manufacturing, surveillance, exploration, learning, and entertainment. Robots can be used, for example, in dangerous and inhospitable environments.

[0004] Some robots require user input and can be operated by humans. Other robots have a degree of autonomy and can operate without human intervention, at least in some situations. Some autonomous robots are designed to mimic human behavior. Autonomous robots are particularly useful in applications where they are required to operate for extended periods of time without operator intervention, navigate within their operating environment, and / or adapt to changing conditions.

[0005] Hydraulics is the science of the mechanical properties and uses of fluids, based on the theoretical foundations of fluid mechanics. In fluid power applications, hydraulics can be used to generate, control, transmit, and distribute power. In robotic applications, hydraulics can be used alone or in combination with electric motors or other power sources to distribute power to robotic components (such as actuators).

[0006] A hydraulic system may include one or more hydraulic valves. Hydraulic valves can control the flow of hydraulic fluid within a hydraulic system. Some hydraulic valves control the flow of hydraulic fluid by opening and closing the valve. Some hydraulic valves control the flow of hydraulic fluid by continuously adjusting the flow rate. Hydraulic valves can be actuated by a handle, knob, or cam, for example, or can be solenoid-operated or pilot-operated.

[0007] Directional control valves can temporarily stop and restart the flow of hydraulic fluid and / or change the direction of flow. An example of a directional control valve is a two-way control valve with two ports, called a supply port and a discharge port.

[0008] A pressure control valve can regulate the pressure of hydraulic fluid in a hydraulic system, for example, by relieving excess pressure.

[0009] Flow control valves can be used to improve the performance of hydraulic systems by regulating the flow of hydraulic fluid through the system. Summary of the Invention

[0010] In a representative example, a miniature hydraulic valve may include a valve body, a fluid path, a plunger, and a piezoelectric material. The valve body has a supply port and an outlet port. The fluid path passes through the valve body and is hydraulically connectable between the supply port and the outlet port, and includes a nozzle having a diameter in a first range of 600 micrometers to 700 micrometers. The plunger is disposed within the fluid path near the nozzle. The piezoelectric material is mechanically coupled to the plunger. The position of the plunger relative to the nozzle depends on at least one dimension of the piezoelectric material, which at least one dimension of the piezoelectric material is responsive to one or more electrical signals from an electrical system. During operation, when the electrical system does not provide power to the piezoelectric material, the plunger is biased against the nozzle, blocking the flow of hydraulic fluid along the fluid path, with a force sufficient to block flow at a fluid pressure of at least 700 pounds per square inch (psi). During operation, when the electrical system provides power to the piezoelectric material, the plunger is displaced from the nozzle, forming a gap between the plunger and the nozzle, allowing hydraulic fluid to flow along the fluid path. The gap is proportional to the power supplied to the piezoelectric material, and the plunger displacement is in a second range of 40 micrometers to 70 micrometers. The gap is sufficient to accommodate hydraulic fluid flow rates of up to 0.5 liters per minute (lpm).

[0011] In another representative example, a hydraulic system can include a miniature hydraulic valve, a fluid path, a plunger, and a piezoelectric material. The miniature hydraulic valve includes a valve body. The valve body has a supply port and an outlet port. A fluid path passes through the valve body, hydraulically communicating the supply port and the outlet port, and includes a nozzle having a diameter in a first range of 600 micrometers to 700 micrometers. The plunger is disposed within the fluid path near the nozzle. The piezoelectric material is mechanically coupled to the plunger. The hydraulic system can further include an electrical system electrically coupled to the piezoelectric material. At least one dimension of the piezoelectric material is responsive to one or more electrical signals from the electrical system, and the position of the plunger relative to the nozzle depends on the at least one dimension of the piezoelectric material. During operation, when the electrical system does not supply power to the piezoelectric material, the plunger is biased against the nozzle, blocking the flow of hydraulic fluid along the fluid path, with a force sufficient to block the flow at a fluid pressure of at least 700 pounds per square inch (psi). In operation, when an electrical system applies power to the piezoelectric material, the plunger displaces from the nozzle, creating a gap between the plunger and the nozzle that allows hydraulic fluid to flow along the fluid path. The gap is proportional to the power applied to the piezoelectric material, and the plunger displacement is in a second range of 40 micrometers to 70 micrometers. The gap is sufficient to accommodate hydraulic fluid flow rates up to 0.5 liters per minute (lpm).

[0012] In another exemplary embodiment, the robot arm may include a hydraulic control system, a hydraulic actuation component, and a hydraulic assembly. The hydraulic control system is physically coupled to the robot body. The hydraulic actuation component is physically coupled to the robot body and enables movement of at least a portion of the robot. The hydraulic assembly may include a miniature hydraulic valve. The miniature hydraulic valve may include a valve body, a fluid path, a plunger, and a piezoelectric material. The valve body has a supply port and an outlet. The fluid path passes through the valve body and is capable of hydraulically connecting the supply port and the outlet, and has a nozzle with a diameter in a first range of 600 micrometers to 700 micrometers. The plunger is disposed within the fluid path near the nozzle. The piezoelectric material is mechanically and communicatively coupled to the plunger. The hydraulic assembly may further include an electrical system electrically coupled to the piezoelectric material, wherein at least one dimension of the piezoelectric material is responsive to one or more electrical signals from the electrical system, and the position of the plunger relative to the nozzle depends on at least one dimension of the piezoelectric material. In operation, when the electrical system does not supply power to the piezoelectric material, the plunger is biased against the nozzle, blocking the flow of hydraulic fluid along the fluid path. This bias is sufficient to block the flow of fluid at a fluid pressure of at least 700 pounds per square inch (psi). In operation, when the electrical system supplies power to the piezoelectric material, the plunger is displaced from the nozzle, creating a gap between the plunger and the nozzle, allowing hydraulic fluid to flow along the fluid path. This gap is proportional to the power supplied to the piezoelectric material, and the plunger displacement is in a second range of 40 micrometers to 70 micrometers. The gap can accommodate hydraulic fluid flow rates up to 0.5 liters per minute (lpm).

[0013] In another representative example, the robot may include a robot body, a hydraulic control system, a hydraulic actuation component, and a hydraulic assembly. The hydraulic control system is physically coupled to the robot body. The hydraulic actuation component is physically coupled to the robot body and is capable of operating at least a portion of the robot. The hydraulic assembly may include a miniature hydraulic valve. The miniature hydraulic valve may include a valve body, a fluid path, a plunger, and a piezoelectric material. The valve body has a supply port and an outlet. The fluid path may pass through the valve body and hydraulically couple the supply port and the outlet, and include a nozzle having a diameter in a first range of 600 micrometers to 700 micrometers. The plunger is disposed within the fluid path near the nozzle. The piezoelectric material is mechanically coupled to the plunger. The hydraulic assembly may further include an electrical system electrically coupled to the piezoelectric material, wherein at least one dimension of the piezoelectric material is responsive to one or more electrical signals from the electrical system, and the position of the plunger relative to the nozzle depends on at least one dimension of the piezoelectric material. In operation, when the electrical system does not supply power to the piezoelectric material, the plunger is biased against the nozzle, blocking the flow of hydraulic fluid along the fluid path. This bias is sufficient to block flow at fluid pressures of at least 700 pounds per square inch (psi). In operation, when the electrical system supplies power to the piezoelectric material, the plunger is displaced from the nozzle, creating a gap between the plunger and the nozzle, allowing hydraulic fluid to flow along the fluid path. This gap is proportional to the power supplied to the piezoelectric material, and the plunger displacement is in a second range of 40 micrometers to 70 micrometers. The gap can accommodate a hydraulic fluid flow rate of up to 0.5 liters per minute (LPM).

[0014] As another representative example, an electrohydraulic valve includes a valve manifold having a supply port and an exhaust port, a valve housing defining a common chamber, a metering port communicating with the common chamber, and a first end coupled to the valve manifold, a first nozzle in fluid communication with the supply port and disposed within the common chamber, the first nozzle having a first nozzle tip with a first orifice, a second nozzle in fluid communication with the exhaust port and disposed within the common chamber, the second nozzle having a second nozzle tip with a second orifice, a first valve plug disposed within the common chamber and opposite the first orifice, and a first valve plug coupled to the first valve plug, the first valve plug contacting the first nozzle tip to close the first orifice, and a second valve plug offset from the first nozzle tip. a first valve actuator operable to move the first valve plug between an open position in which a first gap is formed between the first valve plug and the first orifice to allow fluid to pass from the first orifice to the common chamber; a second valve plug disposed in the common chamber and positioned opposite the second orifice; and a second valve actuator coupled to the second valve plug and operable to move the second valve plug between a closed position in which the second valve plug contacts the second nozzle tip to close the second orifice and an open position in which the second valve plug is offset from the second nozzle tip to allow fluid to pass from the common chamber to the second orifice.

[0015] As another representative example, a method for operating a hydraulic actuator includes applying an electric field to a first valve actuator disposed in a common chamber of a valve unit to axially displace a first valve plug disposed in the common chamber from a first orifice connected to a supply port of a valve manifold, thereby forming a first communication path between the supply port and the common chamber through the first orifice; supplying fluid from a fluid source connected to the supply port to the common chamber through the first communication path; and supplying the fluid from the common chamber to the hydraulic actuator through a metering port of the valve unit. removing an electric field from the first valve actuator to urge the first valve plug against the first orifice to close the first communication path; applying an electric field to a second valve actuator disposed in the common chamber of the valve unit to axially displace a second valve plug disposed in the common chamber from a second orifice connected to an exhaust port of the valve manifold to form a second communication path between the exhaust port and the common chamber through the second orifice; and exhausting fluid from the common chamber through the second communication path to a fluid return connected to the exhaust port. [Brief explanation of the drawings]

[0016] The various elements and acts shown in the figures are intended to supplement the detailed description and are provided for illustrative purposes. Unless otherwise dictated by the specific context, the size, shape, and relative positions of the elements and acts shown in the figures are not necessarily drawn to scale and are not intended to convey any information or limitations. Generally, the same reference numbers are used to identify similar elements or acts. [Figure 1] FIG. 1 is a perspective view of an example implementation of a direct piezoelectric hydraulic valve according to the present systems, devices, and methods. [Figure 2A] 2A is a cross-sectional view of the direct piezoelectric hydraulic valve of FIG. 1 in accordance with the present systems, devices, and methods. [Figure 2B] 2B is a cross-sectional view of a portion of the direct piezoelectric hydraulic valve of FIG. 1 in accordance with the present systems, devices, and methods. [Figure 3A] FIG. 3A is a cross-sectional view of a portion of another implementation of a direct piezoelectric hydraulic valve according to the present systems, devices, and methods. [Figure 3B] 3B is a perspective view of the direct piezoelectric hydraulic valve of the cross-sectional view of FIG. 3A in accordance with the present systems, devices, and methods. [Figure 4A] FIG. 4A is a cross-sectional view of an example implementation of an amplified piezoelectric hydraulic valve in accordance with the present systems, devices, and methods. [Figure 4B] FIG. 4B is a perspective view of a cross section of the amplified piezoelectric hydraulic valve shown in FIG. 4A in accordance with the present systems, devices, and methods. [Figure 5] FIG. 5 is a perspective view of the amplified piezoelectric hydraulic valve shown in FIGS. 4A and 4B in accordance with the present systems, devices, and methods. [Figure 6A] FIG. 6A is a cross-sectional view of another implementation of an amplified piezoelectric hydraulic valve according to the present systems, devices, and methods. [Figure 6B] FIG. 6B is a perspective view of a cross section of the amplified piezoelectric hydraulic valve shown in FIG. 6A in accordance with the present systems, devices, and methods. [Figure 7] FIG. 7 is a perspective view of the amplified piezoelectric hydraulic valve of FIGS. 6A and 6B in accordance with the present systems, devices, and methods. [Figure 8] FIG. 8 is a schematic diagram of an exemplary implementation of a hydraulically powered robot with miniature hydraulic valves integrated into the robot's arm in accordance with the present systems, devices, and methods. [Figure 9] FIG. 9 is a schematic diagram illustrating an example implementation of portions of a hydraulic system in a forearm, wrist, and hand of a robot (e.g., the robot of FIG. 8) according to the present systems, devices, and methods. [Figure 10]FIG. 10 is a screenshot of an example CFD simulation showing the flow path of an example implementation of an amplified piezoelectric hydraulic valve (e.g., the amplified piezoelectric hydraulic valve shown in FIGS. 4A, 4B, and 5) according to the present systems, devices, and methods. [Figure 11] FIG. 11 is a screenshot of a CFD simulation for the same example as FIG. 10, showing the static pressure just above the nozzle of an amplified hydraulic valve (e.g., the amplified piezoelectric hydraulic valve shown in FIGS. 4A, 4B, and 5) according to the present systems, devices, and methods. [Figure 12A] FIG. 12A is a perspective view of an electrohydraulic valve including one valve unit. [Figure 12B] FIG. 12B is a cross-sectional view of the electrohydraulic valve of FIG. 12A. [Figure 12C] FIG. 12C is a cross-sectional view of the electrohydraulic valve of FIG. 12A. [Figure 12D] FIG. 12D is a cross-sectional view of the electrohydraulic valve of FIG. 12A showing the valves within the valve unit in different positions. [Figure 12E] FIG. 12E is a cross-sectional view of the electrohydraulic valve of FIG. 12A showing the valves within the valve unit in different positions. [Figure 12F] FIG. 12F is a cross-sectional view of the electrohydraulic valve of FIG. 12A showing the valves within the valve unit in different positions. [Figure 12G] FIG. 12G is a cross-sectional view of the electrohydraulic valve of FIG. 12A showing the electrical feedthrough and pressure transducer coupled to the cap of the valve unit. [Figure 12H] FIG. 12H is a cross-sectional view of the electrohydraulic valve of FIG. 12A showing the metering ports formed in the cap of the valve unit. [Figure 13] FIG. 13 is a schematic diagram of a hydraulic system using the electrohydraulic valve of FIG. 12A to operate a single-acting hydraulic cylinder. [Figure 14A] FIG. 14A is a perspective view of an electrohydraulic valve including two valve units. [Figure 14B]FIG. 14B is a cross-sectional view of the electrohydraulic valve of FIG. 14A. [Figure 14C] FIG. 14C is a perspective view of a valve pack including a plurality of the electrohydraulic valves of FIG. 14A. [Figure 15] FIG. 15 is a schematic diagram of a hydraulic system using the electrohydraulic valve of FIG. 14A to operate a double-acting hydraulic cylinder. DETAILED DESCRIPTION OF THE INVENTION

[0017] The following description sets forth specific details to explain and provide an understanding of various implementations and embodiments of the present systems, devices, and methods. Those skilled in the art will understand that some specific details described herein may be omitted or changed in alternative implementations and embodiments, and that the various implementations and embodiments described herein may be combined with each other and / or with other methods, components, materials, etc. to produce further implementations and embodiments.

[0018] In some instances, well-known structures and / or processes related to computer systems and data processing have not been shown or provided in detail to avoid unnecessarily complicating or obscuring the description of implementations and embodiments.

[0019] Unless the specific context requires otherwise, throughout this specification and the appended claims, terms such as "comprise" and "have," as well as "include" and variations thereof, are used in an open and inclusive sense, meaning "including but not limited to."

[0020] Throughout this specification and the appended claims, the singular forms "a," "the," "the," "the," and "the" include the plural unless the specific context requires otherwise. For example, references to "an embodiment" and "the embodiment" include "embodiments" and "the implementations," respectively, and references to "an implementation" and "the implementation" include "implementations" and "the implementations," respectively. Similarly, the term "or" is generally used in its broadest sense, meaning "and / or," unless the specific context clearly dictates otherwise.

[0021] The headings and abstract of this disclosure are provided for convenience only and are not intended to, and should not be construed to, interpret the scope or meaning of the present systems, devices, and methods.

[0022] The technology described herein includes systems, devices, and methods for hydraulically driven robots. In particular, the present application describes hydraulic valves suitable for use in hydraulic systems (e.g., hydraulic systems used in hydraulically driven robots). The hydraulic valves may be miniature hydraulic valves.

[0023] In some applications of robotic systems in general, and humanoid robots in particular, it may be desirable for the end effector to have sufficient power and precision while fitting into a particular form factor. It may also be desirable for the couplings (e.g., cables, hoses, wires) between the end effector and other components of the robotic system to be located at least partially inside the robot. External couplings not only detract from aesthetics, but also increase the robot's external dimensions, potentially making it difficult to maneuver the robot in tight spaces. External couplings may also pose a risk of damage to the robot or its surrounding environment, for example, if the coupling gets caught on an object around the robot.

[0024] The technology described herein includes hydraulic valves for hydraulic applications, including, but not limited to, hydraulic systems powering robotic systems. For example, the valves may be used in hydraulic systems powering end effectors of robotic systems (e.g., the hands of a humanoid robot), where some or all of the hydraulic system is adapted and / or miniaturized to fit at least partially inside the robot (e.g., inside a robotic arm).

[0025] In some implementations, at least a portion of the hydraulic system (e.g., at least one hydraulic hose) is routed through a pivot joint (e.g., a shoulder, elbow, forearm, wrist, and / or knuckles of a robotic arm). The pivot joint is an example of a confined space. A confined space may, for example, have a limited volume. The confined space may contain moving components that may interfere with hydraulic hoses within and / or passing through the space, as well as other hydraulic fittings and components within or passing through the space. The confined space may change volume or shape during operation, such as while the robot is moving or performing a task. In confined spaces in general, and in pivot joints as an example, more compact hydraulic fittings are advantageous. Also, in confined spaces, smaller dimensions of hydraulic hoses and fittings (e.g., hydraulic valves) are advantageous.

[0026] The technology described herein includes miniaturized hydraulic valves for hydraulic systems. In some implementations, the hydraulic system is used to control the actuation of various degrees of freedom (DOF) of a robotic hand. As mentioned above, it may be desirable to miniaturize components of the hydraulic system (e.g., hydraulic valves) to fit at least some components within the internal volume of the robot and eliminate, or at least reduce, external hydraulic hoses.

[0027] The technology described herein includes a novel implementation of a miniaturized piezoelectric poppet valve. Poppet valves can be used to control the timing and amount of hydraulic fluid flow to hydraulic devices in hydraulic systems. Poppet valves typically have a) a nozzle with an aperture and b) a plunger that presses against the nozzle (or aperture) to close the valve and stop or at least reduce the flow of hydraulic fluid through the valve. Closing the valve is traditionally accomplished using a spring and / or solenoid. Opening the valve is traditionally accomplished by compressing the spring or solenoid to push or pull the plunger away from the aperture, allowing fluid to flow through the nozzle.

[0028] This technology replaces springs and / or solenoids with piezoelectric materials, and uses electrically controlled actuation (expansion or contraction) of the piezoelectric materials to open the aperture.

[0029] The performance of a hydraulic valve depends on the viscosity of the hydraulic fluid flowing through it. In some implementations, the hydraulic fluid is oil. In some implementations, peanut oil has a viscosity in the range of 60 to 80 centistokes.

[0030] During operation, higher fluid pressure of the hydraulic fluid in the hydraulic system can apply greater force to an end effector of a robotic system, such as a robotic hand of a humanoid robot. In some implementations, it may be desirable for the hydraulic system to have a fluid pressure of at least 700 pounds per square inch (psi). In one implementation, the fluid pressure is 800 psi. Higher fluid pressure places additional stress on hydraulic system components, such as hydraulic valves. The present technology can accommodate fluid pressures that support implementation in a robotic system.

[0031] During operation, the flow rate of hydraulic fluid within a hydraulic system can at least partially determine the speed at which an end effector can move. Typically, the higher the flow rate, the faster the end effector moves. The higher the flow rate, the more difficult it is to control. The present technology can accommodate fluid flow rates that support implementation in a robotic system. In some implementations, the fluid flow rate is less than 0.5 liters per minute (lpm). In one implementation, the fluid flow rate is 0.2 lpm.

[0032] In some applications, it may be desirable for a hydraulic valve to operate efficiently at high pressures and low flow rates. For example, in some robotic systems, the robot's hydraulic system fluid pressure is greater than 700 psi (pounds per square inch), and the robot's hydraulic system hydraulic fluid flow rate is less than 0.4 lpm (liters per minute).

[0033] The miniature hydraulic valves described below are referred to herein as "high pressure, low flow" valves. The technology combines operation at high fluid pressures (e.g., above 700 psi) with low fluid flows (e.g., below 0.5 lpm).

[0034] In some implementations, approximately 40 hydraulic valves are arranged in the internal volume of each robotic arm. In some implementations of existing technology, the hydraulic valves are approximately 2 cm x 2 cm x 2 cm in size, making it difficult to accommodate 40 hydraulic valves in the internal volume of each robotic arm. In some implementations of the present technology, the hydraulic valves are approximately 1 cm x 1 cm x 1 cm in size and arranged in a 2 cm x 2 cm x 10 cm rectangular block inside the forearm of each robotic arm.

[0035] It is desirable that the hydraulic valve consume less power than existing technologies, that the hydraulic valve operate for more cycles than existing technologies, and that the hydraulic valve consume no power in the off state.

[0036] An object or shape is defined as humanoid if it has an appearance or characteristics similar to a human. For example, a humanoid robot is a robot that has a human-like appearance or characteristics. A humanoid robot may be entirely "humanoid" or may have humanoid components (e.g., a torso, head, arms, hands) coupled to non-humanoid components (e.g., a wheeled base). While the following description focuses primarily on hydraulically powered humanoid robots, those skilled in the art will understand that hydraulic systems according to the present technology can be used to control the hands, feet, tails, heads, or any applicable end effectors or actuators of humanoid or non-humanoid robots.

[0037] The use of hydraulics to drive the robot arm and / or end effector is advantageous for the following reasons:

[0038] Hydraulics can provide high speeds and strengths within the envelope of humanoid shapes and sizes.

[0039] To accommodate the constraints of a humanoid's envelope, components (e.g., motors) can be located outside the envelope, or at least outside the volume-constrained area, and hydraulically coupled to components within the envelope. Components in a hydraulic system are said to be hydraulically coupled if they are connected by hydraulic fluid.

[0040] Hydraulics can provide high power density, especially if the motor is located outside of a constrained volume.

[0041] Hydraulics can at least reduce hysteresis, which can manifest as jerky robot movements. Because hydraulic fluids are virtually incompressible, little or no potential energy is released once the static coefficient of friction is exceeded.

[0042] Hydraulics provide concentrated power, allowing the total force to be applied to a single degree of freedom (DOF).

[0043] Hydraulics can provide high fidelity control of the robot, i.e., precise control of the robot's movements.

[0044] Hydraulic systems include hydraulic hoses that provide hydraulic couplings and hydraulic fittings to secure the hydraulic hoses to other hydraulic components (e.g., pumps, valves, actuating pistons, etc.).

[0045] 1 is a perspective view of an exemplary implementation of a hydraulic system 100 including a direct piezoelectric hydraulic valve 102 in accordance with the present systems, devices, and methods. The hydraulic valve 102 has a valve body 104. The valve body 104 has three segments: an upper body 106, a middle body 108, and a lower body 110.

[0046] The upper body 106 has openings 112 and 114, fittings 116 and 118, and electrical pins 120 and 122. The electrical pins 120 and 122 provide an electrical communication connection between the piezoelectric hydraulic valve 102 and an electrical system 124 via electrical wires 126 and 128. The electrical system 124 is operable to provide electrical signals to control the extension of the piezoelectric material within the piezoelectric hydraulic valve 102, as described below in Figures 2A and 2B. The electrical system 124 may include a controller.

[0047] The lower body 110 has a port 130. The port 130 can be a supply or a discharge port. In some implementations, the valve body 104 has a manifold (not shown in FIG. 1 ) with various additional ports that can be used as supplies, discharges, bleed lines, vents, electrical conduits, etc.

[0048] 2A shows a cross-sectional view of the direct piezoelectric hydraulic valve 102 of FIG. 1 in accordance with the present systems, devices, and methods. The direct piezoelectric hydraulic valve 102 has a spring 202. The spring 202 is mechanically coupled to a tee fitting 204. The tee fitting 204 is mechanically coupled to the upper end of a piezoelectric sleeve 206. The tee fitting 204 covers the upper end of the piezoelectric sleeve 206 and extends downward through the interior space of the piezoelectric sleeve 206. In operation, the spring 202 is biased toward the upper surface of the tee fitting 204.

[0049] Piezoelectric sleeve 206 is a length of tubular piezoelectric material. Piezoelectric sleeve 206 can comprise, for example, lead zirconate titanate (PZT) comprised of one or more PZT stacks. Piezoelectric sleeve 206 is housed in a hollow cylinder 208. Piezoelectric sleeve 206 extends from tee fitting 204 to plunger 210, which is mechanically coupled to plunger 210 via piezoelectric sleeve 206. Plunger 210 has a gasket 212.

[0050] The nozzle 214 is hydraulically coupled to the port 130. In some implementations, the diameter of the nozzle 214 is in the range of 600 micrometers (μm) to 700 μm.

[0051] Portion 216 of direct piezoelectric hydraulic valve 102 is described below with reference to FIG. 2B.

[0052] 2B is a cross-sectional view of portion 216 of the direct piezoelectric hydraulic valve 102 of FIG. 1 according to the present systems, devices, and methods. Portion 216 is identified in FIG. 2A. Portion 216 includes the center body 108, the lower body 110, the port 130, the lower end of the piezoelectric sleeve 206, the plunger 210, and the gasket 212.

[0053] 1, 2A, and 2B, hydraulic fluid enters the lower body 110 of the hydraulic valve 102 through port 130. The hydraulic fluid flows upward through a nozzle 214 toward a gasket 212. The nozzle 214 has a narrow channel that extends along the longitudinal axis of the lower body 110.

[0054] The gasket 212 is held in place by the plunger 210 . In some implementations, the gasket 212 comprises a polytetrafluoroethylene (PTFE) material. As mentioned above, the plunger 210 is mechanically coupled to the piezoelectric sleeve 206. The piezoelectric sleeve 206 is biased toward the nozzle 214 by the spring 202 and the T-joint 204 at the top end of the piezoelectric sleeve 206.

[0055] An electrical system (not shown in FIGS. 2A and 2B) is electrically and communicatively connected to the piezoelectric sleeve 216. At least one dimension of the piezoelectric sleeve 216 can be responsive to one or more electrical signals from the electrical system. For example, the length of the piezoelectric sleeve 206 along the longitudinal axis of the hydraulic valve 102 can be responsive to the electrical signals from the electrical system. For example, the electrical signal can increase the length of the piezoelectric sleeve 206 (i.e., extend the piezoelectric sleeve 206). The position of the plunger 210 relative to the nozzle 214 can depend on at least one dimension of the piezoelectric sleeve 206, such as the length of the piezoelectric sleeve 206.

[0056] In operation, while no electric field (E-field) is applied to the piezoelectric sleeve 206, the spring 202 biases the piezoelectric sleeve 206 toward the plunger 210, holding the gasket 212 in the upper opening of the nozzle 214. In this state, the direct piezoelectric hydraulic valve 102 is closed.

[0057] When an electric field is applied to the piezoelectric sleeve 206, the piezoelectric sleeve 206 expands longitudinally, biasing the tee fitting 204 against the spring 202 and pulling the gasket 212 upward and away from the top opening of the nozzle 214. In this state, the direct piezoelectric hydraulic valve 102 is open, allowing hydraulic fluid to flow through the nozzle 214. The hydraulic fluid can enter the volume around the gasket 212 and exit the direct piezoelectric hydraulic valve 102 through an exhaust port (not shown in FIG. 2B ).

[0058] In some implementations, the hydraulic fluid flowing directly from the port 130 (supply) to the exhaust port (exhaust) of the piezoelectric hydraulic valve 102 is oil, such as peanut oil or mineral oil.

[0059] A hydraulic hose (not shown in FIG. 1) can be attached to port 130 using an appropriate hydraulic fitting. Similarly, another hydraulic hose (not shown in FIG. 1) can be attached to the exhaust port of direct piezoelectric hydraulic valve 102, which is described below with reference to direct piezoelectric hydraulic valve 300 of FIGS. 3A and 3B.

[0060] The length of the piezoelectric hydraulic valve 102 can be determined, at least in part, depending on the desired flow rate at the nozzle 214. In one implementation, the length of the piezoelectric hydraulic valve 102 illustrated in FIGS. 1, 2A, and 2B is approximately 6 cm. In an implementation where the desired flow rate is 0.2 lpm, the gasket 212 can move between 40 micrometers (μm) and 70 μm. Generally, the pressure exerted on the gasket 212 by the spring 202 is desirably balanced by hydraulic fluid pressure within the piezoelectric valve 102 with an appropriate longitudinal extension of the piezoelectric sleeve 206. In one implementation, the hydraulic fluid pressure within the piezoelectric valve 102 is approximately 800 psi, and the length of the piezoelectric sleeve 206 is 40 mm to achieve the appropriate longitudinal extension of the piezoelectric sleeve 206.

[0061] In some applications, it may be desirable for the piezoelectric hydraulic valve to be less than 6 cm in length. An example of an application where further miniaturization is advantageous is an application where a large number of piezoelectric hydraulic valves (e.g., 40 piezoelectric hydraulic valves) are placed in a limited space, such as the forearm of a hydraulically powered humanoid robot.

[0062] 3A is a cross-sectional view of a portion of another implementation of a direct piezoelectric hydraulic valve 300 according to the present systems, devices, and methods. The direct piezoelectric hydraulic valve 300 includes a central body 302, a lower body 304, a piezoelectric sleeve 306 disposed within an interior cylindrical volume 308 of the central body 302, a plunger 310, a gasket 312, a nozzle 314, a supply port 316, and an outlet port 318.

[0063] In operation, when direct piezoelectric hydraulic valve 300 is open, hydraulic fluid flows through direct piezoelectric hydraulic valve 300 in the directions indicated by arrows A, B, C, D, and F from supply port 316 to outlet port 318.

[0064] FIG. 3B is a perspective view of a direct piezoelectric hydraulic valve 300 showing the cross section of FIG. 3A in accordance with the present systems, devices, and methods.

[0065] 4A is a cross-sectional view of an exemplary implementation of the present systems, devices, and methods of an amplified piezoelectric hydraulic valve 400. The amplified piezoelectric hydraulic valve 400 is more compact than the direct piezoelectric hydraulic valve 102 shown in FIGS. 1 and 2A.

[0066] The amplified piezoelectric hydraulic valve 400 has an upper body 402, a center body 404, and a lower body 406. In some implementations, the valve body 402 includes or is fabricated from aluminum. The upper body 402 has a center port 408 and two side ports 410a and 410b.

[0067] The central body 404 has a housing 412 that encloses a chamber 414. The chamber 414 houses a piezoelectric block 416. The piezoelectric block 416 is mechanically coupled to a plunger 418. The plunger 418 has a gasket 420. In the amplified piezoelectric hydraulic valve 400, the piezoelectric sleeve 206 of the direct piezoelectric hydraulic valve 102 shown in FIGS. 1, 2A, and 2B is replaced with the piezoelectric block 416. An electric field (E-field) applied to the piezoelectric block 416 causes the piezoelectric block 416 to contract in size. Because the piezoelectric block 416 is an ellipsoid, the contraction of the piezoelectric block 416 is at least partially magnified.

[0068] The lower body 406 includes a nozzle 422. In some implementations, the diameter of the nozzle 422 ranges from 600 micrometers (μm) to 700 μm. In operation, when the amplified piezoelectric hydraulic valve 400 is closed, the piezoelectric block 416 biases the plunger 418 and gasket 420 against the nozzle 422, stopping or at least reducing the flow of hydraulic fluid through the amplified piezoelectric hydraulic valve 400.

[0069] An electrical system (not shown in FIG. 4A ) can be electrically and communicatively connected to the piezoelectric block 416. At least one dimension of the piezoelectric block 416 can be responsive to one or more electrical signals from the electrical system. The position of the plunger 418 relative to the nozzle 422 can depend on at least one dimension of the piezoelectric block 416. For example, if the piezoelectric block 416 is an ellipsoid, the minor axis of the ellipsoid can be responsive to an electrical signal from the electrical system.

[0070] In operation, while no electric field (E-field) is applied to the piezoelectric block 416, the piezoelectric block 416 biases the plunger 418 to hold the gasket 420 in the upper opening of the nozzle 422. In this state, the amplified piezoelectric hydraulic valve 400 is closed.

[0071] When an E-field is applied to the piezoelectric block 416 , the piezoelectric block 416 contracts sufficiently to open the amplified piezoelectric hydraulic valve 400 and allow hydraulic fluid to flow through the amplified piezoelectric hydraulic valve 400 .

[0072] In some implementations, the contraction of the piezoelectric block 416 is sufficient to create a gap in the range of 40 μm to 70 μm between the gasket 420 and the nozzle 422. In these implementations, the flow rate of hydraulic fluid through the amplified piezoelectric hydraulic valve 400 may be approximately 0.2 lpm, and the physical dimensions of the amplified piezoelectric hydraulic valve 400 may be approximately 1 cm x 1 cm x 1 cm.

[0073] In some implementations, the gap between the gasket 420 and the nozzle 422 is proportional to the power of the electric field applied to the piezoelectric block 416. This proportionality of the amplified piezoelectric hydraulic valve 400 is one of its advantages. In operation, the amplified piezoelectric hydraulic valve 400 can regulate the flow rate of hydraulic fluid through the amplified piezoelectric hydraulic valve 400 with very high resolution to a value ranging from 0 to a predetermined upper limit. The predetermined upper limit may be less than the design limit of the piezoelectric hydraulic valve 400.

[0074] In an example implementation, the resolution is 0.00006 times the range. In the same example implementation, if the predetermined upper limit for the flow of hydraulic fluid through the amplified piezoelectric hydraulic valve 400 is 0.4 lpm, the amplified piezoelectric hydraulic valve 400 can adjust the flow of hydraulic fluid through the amplified piezoelectric hydraulic valve 400 in increments of 0.000024 lpm.

[0075] The lower body 406 also includes a supply port 424, a supply chamber 426, and a discharge chamber 428. In operation, when the amplified piezoelectric hydraulic valve 400 is open, hydraulic fluid can flow through the amplified piezoelectric hydraulic valve 400 from the supply port 424 to the discharge chamber 428 in the directions indicated by arrows A, B, C, D, E, and F.

[0076] 4B is a perspective view of an amplified piezoelectric hydraulic valve 400 showing the cross section of FIG. 4A in accordance with the present systems, devices, and methods. The amplified piezoelectric hydraulic valve 400 has an exhaust port 430 fluidly connected to an exhaust chamber 428.

[0077] FIG. 5 is a perspective view of an amplified piezoelectric hydraulic valve 400 showing the cross section of FIGS. 4A and 4B in accordance with the present systems, devices, and methods.

[0078] Figure 6A is a cross-sectional view of another exemplary implementation of an amplified piezoelectric hydraulic valve 600 according to the present systems, devices, and methods. The amplified piezoelectric hydraulic valve 600 is a variation of the amplified piezoelectric hydraulic valve 400 shown in Figures 4A, 4B, and 5. The amplified piezoelectric hydraulic valve 600 is smaller than the amplified piezoelectric hydraulic valve 400 shown in Figures 4A, 4B, and 5.

[0079] The amplified piezoelectric hydraulic valve 600 has an upper body 602, a center body 604, and a lower body 606. In some implementations, the valve body 602 includes or is fabricated from aluminum. The upper body 602 has a center port 608 and two side ports 610a and 610b.

[0080] The central body 604 has a housing 612 that encloses a chamber 614. The chamber 614 contains a piezoelectric block 616. The piezoelectric block 616 is mechanically coupled to a gasket 618. An electric field (E-field) applied to the piezoelectric block 616 can cause the piezoelectric block to contract (i.e., decrease in size).

[0081] The lower body 606 has a nozzle 620. In some implementations, the diameter of the nozzle 620 ranges from 600 micrometers (μm) to 700 μm. In operation, when the amplified piezoelectric hydraulic valve 600 is closed, the piezoelectric block 616 biases the gasket 618 against the nozzle 620, preventing or at least reducing the flow of hydraulic fluid through the amplified piezoelectric hydraulic valve 600. When an E-field is applied to the piezoelectric block 616, the piezoelectric block 616 contracts sufficiently to open the amplified piezoelectric hydraulic valve 600 and allow hydraulic fluid to flow through the amplified piezoelectric hydraulic valve 600.

[0082] In some implementations, the contraction of the piezoelectric block 616 is sufficient to create a gap in the range of 40 μm to 70 μm between the gasket 618 and the nozzle 620. In these implementations, the flow rate of hydraulic fluid through the amplified piezoelectric hydraulic valve 600 is approximately 0.2 lpm, and the physical dimensions of the amplified piezoelectric hydraulic valve 600 can be less than approximately 1 cm x 1 cm x 1 cm.

[0083] The lower body 606 also has a supply port 622, a supply chamber 624, and a discharge chamber 626. In operation, when the amplified piezoelectric hydraulic valve 600 is open, hydraulic fluid can flow from the supply port 622 to the discharge chamber 626 through the amplified piezoelectric hydraulic valve 600.

[0084] Figure 6B is a perspective view of an amplified piezoelectric hydraulic valve 600 showing the cross section of Figure 6A in accordance with the present systems, devices, and methods. The amplified piezoelectric hydraulic valve 600 has an exhaust port 628 (see Figure 7) fluidly coupled to an exhaust chamber 626 (see Figure 6A).

[0085] FIG. 7 is a perspective view of the amplified piezoelectric hydraulic valve 600 of the cross section of FIGS. 6A and 6B in accordance with the present systems, devices, and methods.

[0086] 8 is a schematic diagram illustrating an example implementation of a hydraulically driven robot 800 in accordance with the present systems, devices, and methods, with a hydraulic pump 802 integrated into an arm 804a of the robot 800. The hose is also referred to herein as a hydraulic hose.

[0087] The robot 800 comprises a base 806 and a humanoid upper body 808 . Base 806 is comprised of a pelvis 810 and two legs 812a and 812b (collectively referred to as "legs 812"). Only the tops of legs 812 are shown in Figure 8. In other implementations, base 806 may be comprised of a stand and (optionally) one or more wheels.

[0088] The upper body 808 is comprised of a torso 814, a head 816, a right arm 804a and a left arm 804b (collectively referred to as arms 804), and a right hand 818a and a left hand 818b (collectively referred to as hands 818). The arms 804 of the robot 800 are also referred to herein as robotic arms. The arms 804 of the robot 800 are humanoid arms. In other implementations, the arms 804 have a form factor that differs from that of a humanoid arm.

[0089] The hands 818 are also referred to herein as end effectors. In other implementations, the hands 818 have a form factor that differs from that of a humanoid hand. Each hand 818 has one or more digits, such as digit 820 of hand 818a. The digits can include fingers, thumbs, or similar structures of the hand or end effector.

[0090] In some implementations, the base 804 and / or fuselage 814 of the upper body 808 houses, for example, a hydraulic control system. In some implementations, the hydraulic control system components may be located outside the robot, for example, on a wheeled unit that rotates with the robot as it moves, or in a fixed station to which the robot is fixed.

[0091] The hydraulic control system of the robot 800 includes a hydraulic pump 802 housed in the arm 804a, a reservoir 822, and an accumulator 824. A hose 826 provides a hydraulic coupling between the accumulator 824 and a pressure valve 828 of the hydraulic control system. A hose 830 provides a hydraulic coupling between a discharge valve 832 of the hydraulic control system and the reservoir 822.

[0092] Pressure valve 828 is hydraulically connected to actuation piston 834 by hose 836. Actuation piston 834 is hydraulically connected to exhaust valve 832 by hose 838. Hoses 826 and 836 and pressure valve 828 provide a forward path to actuation piston 834. Hoses 830 and 838 and exhaust valve 832 provide a return path to actuation piston 834. Pressure valve 828 and exhaust valve 832 can control and move actuation piston 834, which can cause corresponding movement of at least a portion of hand 818a, e.g., finger structure 820.

[0093] In some implementations, pressure valve 828 and exhaust valve 832 are electrohydraulic servo valves controlled by a controller (not shown in FIG. 8 ). Electrohydraulic servo valves are also referred to herein as servo valves and servo-controlled valves. The controller can be implemented by any suitable combination of hardware, software, and / or firmware. The controller can include, for example, one or more application-specific integrated circuits, standard integrated circuits, and / or computer programs executed by any number of computers, microcontrollers, and / or processors (e.g., microprocessors, central processing units, etc.). In other implementations, other suitable types of valves can be used.

[0094] In another implementation, the hydraulic drive mechanism includes a motor and a drive piston. The drive piston can be propelled linearly forward by a lead screw that can be coupled to the motor via a flexible shaft coupler. The drive piston can be hydraulically coupled to a hose containing hydraulic fluid. The hose extends from the drive piston to an actuation piston elsewhere on the robot 800, such as in the hand 818a. When the drive piston is driven by the motor, it forces the actuation piston to move, causing a corresponding movement of at least a portion of the robot 800.

[0095] In some implementations, the hydraulic fluid in the hydraulic hoses of FIG. 8 (including hoses 826, 830, 836, and 838) is an oil, such as, for example, peanut oil or mineral oil.

[0096] Each hand 818 can have multiple degrees of freedom (DOF). In some implementations, each hand has up to 18 degrees of freedom. Each degree of freedom can be driven by a respective actuation piston (e.g., actuation piston 834). In FIG. 8, only one actuation piston is shown for clarity. Each actuation piston may be located in a hand 818 .

[0097] A single-acting piston can use a spring to provide return motion for the piston. The degrees of freedom (DOF) can be double-acting to allow for push-pull motion. This means that there is a hose connected to each side of the actuating piston. In one implementation, there are two double-acting degrees of freedom (DOF), resulting in 20 hoses plumbed to each hand 818 to control 18 degrees of freedom for each hand. In some implementations, at least some of the hoses shown in FIG. 8 (e.g., hoses 826, 830, 836, and 838) belong to a hose bundle that can accommodate 20 1 / 8-inch (1 / 8-inch) hoses.

[0098] In some implementations, a robot incorporating a hydraulic system, such as robot 800 of FIG. 8, may employ some or all of the teachings of U.S. Provisional Patent Application No. 63 / 191,732, "Systems, Devices, and Methods for Hydraulic Robotic Arms," ​​filed May 21, 2021, which is incorporated herein by reference in its entirety.

[0099] While Figure 8 illustrates an example implementation of a hydraulically driven robot with only a single-acting hydraulic system, one skilled in the art will appreciate that a hydraulically driven robot can include multiple hydraulic systems. In some implementations, at least some of the multiple hydraulic systems are hydraulically isolated from one another. In some implementations, at least some of the multiple hydraulic systems share a common hydraulic pump.

[0100] It may be beneficial for a hydraulically driven robot to have multiple hydraulically isolated hydraulic systems. For example, a hydraulically driven robot may have multiple components or devices, including hydraulic actuators. A single-acting hydraulic system operable to control hydraulic actuators for multiple components or devices may be too large, complex, or expensive to be practical. For example, it is difficult to route hydraulic hoses from a single shared pump to multiple components or devices in different areas of the robot (especially internally, as in robot 800). Hydraulic systems dedicated to a single component or device, or to a subset of multiple components or devices, are more localized and can be easily adapted to a desired form factor.

[0101] The direct piezoelectric hydraulic valve 102 of Figures 1, 2A, and 2B, the amplified piezoelectric hydraulic valve 400 of Figures 4A, 4B, and 5, and / or the amplified piezoelectric hydraulic valve 600 of Figures 6A, 6B, and 7 may be used in the hydraulic control system of the robot 800 to control the flow of hydraulic fluid within the hydraulic control system. The direct piezoelectric hydraulic valve 102 of Figures 1, 2A, and 2B, the amplified piezoelectric hydraulic valve 400 of Figures 4A, 4B, and 5, and / or the amplified piezoelectric hydraulic valve 600 of Figures 6A, 6B, and 7 may be used in the pressure valve 828 and / or the exhaust valve 832, for example.

[0102] In some implementations, the pressure valve 828 and the exhaust valve 832 can be replaced with a single hydraulic valve having two channels that can be used to control the pressure to and exhaust flow from the actuation piston.

[0103] The direct piezoelectric hydraulic valve 102 of FIGS. 1, 2A, and 2B, the amplified piezoelectric hydraulic valve 400 of FIGS. 4A, 4B, and 5, and / or the amplified piezoelectric hydraulic valve 600 of FIGS. 6A, 6B, and 7 can be more compact than other types of hydraulic valves and can be advantageously deployed in situations where there is limited space and / or where multiple hydraulic connections are required.

[0104] 9 is a schematic diagram illustrating an example implementation of portions 900 of a hydraulic system for a forearm 902, wrist 904, and hand 906 of a robot (e.g., robot 800 of FIG. 8) according to the present systems, devices, and methods. The hand 906 has digits 908.

[0105] The forearm 902 has a series of valves 910 integrated with the forearm 902. The valves 910 include valve 910-1. (For clarity of illustration, only one valve is labeled.) The valves 910 may include a pressure valve and a discharge valve. The valves 910 may include electrohydraulic servo valves and may be operated by a controller (not shown in FIG. 9).

[0106] Finger structure 908 has an actuation piston 912 integral with finger structure 908. Actuation piston 912 is hydraulically connected to valve 910 via pressure hose 914 and exhaust hose 916.

[0107] A pressure hose 914 and a discharge hose 916 pass through wrist 904. While wrist 904 may be a restricted space (as discussed above), and the diameters of hoses 914 and 916 generally need to be large enough to meet the pressure / force requirements of hydraulic system portion 900, the diameter of each of hoses 914 and 916 is preferably small enough in the region of wrist 904 and flexible enough to allow manipulation of wrist 904.

[0108] The direct piezoelectric hydraulic valve 102 of Figures 1, 2A, and 2B, the amplified piezoelectric hydraulic valve 400 of Figures 4A, 4B, and 5, and / or the amplified piezoelectric hydraulic valve 600 of Figures 6A, 6B, and 7 can be used in the hydraulic control system portion 900 of Figure 9 to control the flow of hydraulic fluid within the hydraulic control system. The direct piezoelectric hydraulic valve 102 of Figures 1, 2A, and 2B, the amplified piezoelectric hydraulic valve 400 of Figures 4A, 4B, and 5, and / or the amplified piezoelectric hydraulic valve 600 of Figures 6A, 6B, and 7 can be used in valve 910, for example. In some embodiments, the direct piezoelectric hydraulic valve 102 of FIGS. 1, 2A, and 2B, the amplified piezoelectric hydraulic valve 400 of FIGS. 4A, 4B, and 5, and / or the amplified piezoelectric hydraulic valve 600 of FIGS. 6A, 6B, and 7 may be used to control both pressure flow and exhaust flow to and / or from an actuation piston (e.g., actuation piston 912).

[0109] 9, the forearm 902, wrist 904, and hand 906 are limited spaces and may require numerous hydraulic connections (e.g., connections to valves 910). In one implementation, there are two double-acting degrees of freedom (DOF), resulting in 20 hoses connected to the hand 906 to control 18 DOF for each hand. In some implementations, there are 20 1 / 8 inch (1 / 8 inch) hoses to accommodate the forearm 902, wrist 904, and hand 906.

[0110] As discussed above, it is desirable for hydraulic valves to operate efficiently at high pressures and low flow rates. The above-described miniature hydraulic valves are referred to herein as "high pressure, low flow" valves. For example, the miniature hydraulic valves described herein can combine operation at high fluid pressures (e.g., above about 700 psi) with low fluid flow rates (e.g., below about 0.5 lpm).

[0111] For example, in a robotics application, the fluid pressure and fluid flow rate in a hydraulic valve used to operate an element of a robotic hand can be related to the desired performance of the robotic hand and the desired physical dimensions and form factor of the hydraulic valve. It is an aspect of the present technology that the nozzle size and stroke of the hydraulic valve can be determined, at least in part, from the desired performance of the hydraulic valve and the desired physical dimensions and form factor of the hydraulic valve. Determining the nozzle size and stroke of the hydraulic valve can include analysis and / or simulation, for example, computational fluid dynamics (CFD) simulation.

[0112] FIG. 10 is a screenshot 1000 of a CFD simulation showing the flow path of an example implementation of an amplified piezoelectric hydraulic valve (e.g., the amplified piezoelectric hydraulic valve 400 shown in FIGS. 4A, 4B, and 5) in accordance with the systems, devices, and methods of the present invention.

[0113] Screenshot 1000 includes a supply inlet 1002, an outlet 1004, and a flow path 1006 (e.g., flow paths 1006-1 and 1006-2). Screenshot 1000 shows the results of a CFD simulation for an example 40 μm stroke of an amplified piezoelectric hydraulic valve. The CFD simulation results shown in screenshot 1000 show that, for illustrative purposes, a desirable upper limit of fluid flow rate is achievable with an example 40 μm stroke. Other implementations of the present invention may have different strokes.

[0114] FIG. 11 is a screenshot 1100 of the same example CFD simulation as FIG. 10, showing the static pressure immediately adjacent to and above the nozzle of an amplified hydraulic valve (e.g., the amplified piezoelectric hydraulic valve 400 shown in FIGS. 4A, 4B, and 5) according to the present systems, devices, and methods.

[0115] Screenshot 1100 has a nozzle 1102 with a channel 1104. Screenshot 1100 shows the static pressure at the top of channel 1104 where it exits nozzle 1102. The example CFD simulation results shown in Figure 11 are for an amplified piezoelectric hydraulic valve with a 40 μm gap between the top of channel 1104 of nozzle 1102 and the gasket (e.g., gasket 420 of amplified piezoelectric hydraulic valve 400 shown in Figures 4A, 4B, and 5) and are provided for illustrative purposes.

[0116] The results of the CFD simulation shown in screenshot 1100 indicate that the desired fluid pressure is achievable with the example stroke of 40 μm and the example nozzle dimensions used in the CFD simulation. Other implementations of the present technology may use different strokes and / or nozzle dimensions.

[0117] 12A-12C show an example of an electro-hydraulic valve 1200 including a valve unit 1201. The valve unit 1201 is disposed on a first side of a valve manifold 1202 having a supply port 1218 and an exhaust port 1220. The valve unit 1201 has a common chamber 1208 including a first valve 1203 that can open and close a supply orifice 1210 and a second valve 1205 that can open and close an exhaust orifice 1214. The supply orifice 1210 is fluidly connected to the supply port 1218 of the valve manifold 1202, and the exhaust orifice 1214 is fluidly connected to the exhaust port 1220 of the valve manifold 1202. The valve unit 1201 has a metering port 1222 fluidly connected to the common chamber 1208. The metering port 1222 can be connected to a hydraulic actuator (e.g., a single-acting hydraulic cylinder). The valve unit 1201 may include a pressure transducer 1225 for measuring the pressure in the common chamber 1208 .

[0118] FIG. 13 is a simplified circuit diagram illustrating an example of a hydraulic system 1300 including the electro-hydraulic valve 1200. The valve manifold supply port 1218 (see FIGS. 12B-12C) can be fluidly connected to an accumulator 1302 via a main manifold 1318. The accumulator 1302 receives pressurized fluid (e.g., oil) from a pump 1304 having a suction end fluidly connected to a reservoir 1314. The hydraulic fluid pumped from the pump 1304 to the accumulator 1302 can pass through a directional valve 1316, a high-pressure filter 1306, a check valve 1308, and the main manifold 1318. The hydraulic system 1300 can have a dump valve 1310 fluidly connected to the reservoir 1314. The dump valve 1310 can vent pressure in the accumulator 1302 when the hydraulic system 1300 is turned off. The metering port 1222 of the valve unit (see FIGS. 12B-12C) may be connected to a hydraulic actuator 1312 via a hydraulic line 1320. The valve manifold exhaust port 1220 may be fluidly connected to a reservoir 1314.

[0119] The hydraulic system 1300 can operate in various modes. In a first mode, the first valve 1203 is open and the second valve 1205 is closed. In this mode, pressurized fluid from the accumulator 1302 can enter the common chamber 1208 through the supply gap formed by the supply port 1218 and the open first valve 1203. The pressurized fluid in the common chamber 1208 is supplied to the hydraulic actuator 1312 through the metering port 1222 and the hydraulic line 1320. The flow rate of hydraulic fluid to the common chamber 1208 can be controlled based on the power demand of the hydraulic actuator 1312. The power applied to the hydraulic actuator 1312 can be determined by measuring the pressure in the common chamber 1208 using the pressure transducer 1225. In a second mode, the first valve 1203 can be closed while the second valve 1205 is open. In this mode, fluid in the common chamber 1208 is discharged to the reservoir 1314 through the discharge gap formed by the open second valve 1205 and the discharge port 1220. In a third mode, the first valve 1203 and the second valve 1205 can be opened. In this mode, fluid can be circulated through the common chamber 1208 from the supply port 1218, through the supply gap formed by the open first valve 1203 and the discharge gap formed by the open second valve 1205, and to the discharge port 1220.

[0120] 12B and 12C, the valve unit 1200 can have a valve housing 1231 including a valve body 1232 and a valve cap 1234. The valve cap 1234 can be attached to or integrally formed with a first end of the valve body 1232. A second end of the valve body 1232 is disposed on or attached to a first side of a manifold block 1236 of the valve manifold 1202 such that the valve cap 1234 faces the first side of the manifold block 1236. The valve housing 1231 can be secured to the manifold block 1236 using any suitable method, such as using bolts 1238 that extend through holes in the valve cap 1234 and the valve body 1232 and are inserted into holes in the manifold block 1236.

[0121] A common chamber 1208 is defined within the valve body 1232 and extends between an opposing valve cap 1234 and a first side of a manifold block 1236. One or more sealing members (or gaskets) 1240 may be disposed at the interface between the valve body 1232 and the valve cap 1234 to prevent leakage of the common chamber fluid from that interface. One or more sealing members (or gaskets) 1242 may be disposed at the interface between the manifold block 1236 and the valve body 1232 to prevent leakage of the common chamber fluid from that interface.

[0122] The manifold block 1236 includes the supply port 1218 and the exhaust port 1220 of the valve manifold 1202. The manifold block 1236 can have a first hole 1244 that extends to the first portion 1208a of the common chamber 1208 and is connected to the supply port 1218. The manifold block 1236 can have a second hole 1246 that extends to the second portion 1208b of the common chamber 1208 and is connected to the exhaust port 1220.

[0123] The manifold block 1236 has a supply port 1218. The manifold block 1236 can have a first hole 1244 connected to the supply port 1218 and extending to the first portion 1208a of the common chamber 1208. The valve unit 1201 can have a supply nozzle 1212 having a tip including a supply orifice 1210. The supply nozzle 1212 can be attached to the first hole 1244 such that the tip of the supply nozzle 1212 with the supply orifice 1210 extends into the chamber portion 1208a. One or more sealing members (or gaskets) 1248 can be disposed at the interface between the supply nozzle 1212 and the wall of the first hole 1244 to prevent common chamber fluid from leaking from that interface.

[0124] The manifold block 1236 has an exhaust port 1220. The manifold block can have a second hole 1246 connected to the exhaust port 1220 and extending to the second portion 1208b of the common chamber 1208. The valve unit 1201 can have an exhaust nozzle 1216 having a tip including an exhaust orifice 1214. The exhaust nozzle 1216 can be attached to the second hole 1246, with the exhaust orifice 1214, including the tip of the exhaust nozzle 1246, extending into the chamber portion 1208b. One or more sealing members (or gaskets) 1250 can be disposed at the interface between the exhaust nozzle 1216 and the wall of the second hole 1246 to prevent common chamber fluid from leaking from that interface.

[0125] The manifold block 1236 can have a third hole 1245 and a fourth hole 1247, which are opposite the first hole 1244 and the second hole 1246, respectively. The third and fourth holes 1245, 1247 can accommodate additional supply and exhaust nozzles when two valve units are positioned on opposite sides of the manifold block 1236 (see FIG. 14B). If the third and fourth holes 1245, 1247 are not used, an end cap 1249 can be attached to close the third and fourth holes 1245, 1247 and prevent fluid from exiting the valve manifold through the third and fourth holes 1245, 1247.

[0126] A first valve 1203 disposed within chamber portion 1208a has a first valve plug 1204 (or first valve plunger) movable to close or open a supply orifice 1210. When the supply orifice 1210 is open, a fluid communication path is formed extending from the supply port 1218, through the supply orifice 1210, and into the common chamber 1208. The first valve 1203 has a first valve actuator 1226 coupled to the first valve plug 1204 and operable to move the first valve plug 1204 between a closed position and an open position.

[0127] A second valve 1205 disposed within chamber portion 1208b has a second valve plug 1206 movable to close or open an exhaust orifice 1214. When the exhaust orifice 1214 is open, a fluid communication path is formed, extending from the common chamber 1208 through the exhaust orifice 1214 to an exhaust port 1220. The second valve 1205 has a second valve actuator 1228 coupled to the second valve plug 1206 and operable to move the second valve plug 1206 between a closed position and an open position.

[0128] The first valve plug 1204 is disposed in the chamber portion 1208a opposite the supply orifice 1210. The first valve plug 1204 can be axially aligned with the supply nozzle 1212 (e.g., along the axial axis L1). The first valve plug 1204 can have a holder 1252 and a pad 1254 fitted into an opening in the holder 1252. The holder 1252 can be coupled to the first valve actuator 1226 (e.g., by a threaded pin 1256). The pad 1254 is exposed at a distal end of the first valve plug 1204 and is disposed opposite the supply orifice 1210. The pad 1254 can be, for example, flat and disc-shaped. The pad 1254 has a size (e.g., diameter) larger than the size of the feed orifice 1210 so that the pad 1254 can cover the feed orifice 1210 when the first valve plug 1204 is biased against the tip of the feed nozzle 1212. In some examples, the feed orifice 1210 can have a diameter in the range of 600 microns to 700 microns. The pad 1254 can be formed of a material (e.g., PTFE) that can form a seal against the tip of the feed nozzle 1212.

[0129] The second valve plug 1206 is disposed in the chamber portion 1208b opposite the discharge orifice 1214. The second valve plug 1206 may be axially aligned with the discharge nozzle 1216 (e.g., along an axial axis L2, which may be parallel to the axial axis L1). The second valve plug 1206 may have a holder 1280 and a pad 1282 fitted into an opening in the holder 1280. The holder 1280 may be coupled to the second valve actuator 1228 (e.g., by a threaded pin 1284). The pad 1282 is exposed at a distal end of the second valve plug 1206 and is disposed opposite the discharge orifice 1214. The pad 1282 may be, for example, flat and disc-shaped. The pad 1282 has a size (e.g., diameter) larger than the diameter of the discharge orifice 1214 so that the pad 1282 can cover the discharge orifice 1214 when the second valve plug 1206 is biased against the tip of the discharge nozzle 1216. In some examples, the diameter of the discharge orifice 1214 can be in the range of 600 microns to 900 microns. The pad 1282 can be formed of a material (e.g., PTFE) that can form a seal against the tip of the discharge nozzle 1216.

[0130] In some examples, the first valve actuator 1226 can have a piezoelectric actuator 1258 (or multiple piezoelectric actuators) that can deform axially in response to an applied electric field (e.g., an applied voltage or current). The axial deformation of the piezoelectric actuator 1258 can translate into axial movement of the first valve plug 1204 within the chamber portion 1208a. In one example, the piezoelectric actuator 1258 can be an amplified piezoelectric actuator having a piezoelectric element 1260 mounted within a flexure housing 1262. The first valve plug 1204 can be coupled to the flexure housing 1262 (e.g., by a threaded pin 1256). When an electric field is applied to the piezoelectric actuator 1258, the piezoelectric element 1260 extends laterally (e.g., transverse to the axial axis L1) and the flexure housing 1262 shortens axially (e.g., parallel to the axial axis L1). The amount that the flexure housing 1262 shortens is proportional to the applied electric field and determines the axial displacement of the first valve plug 1204 in a direction parallel to the axial axis L1.

[0131] In some examples, the second valve actuator 1228 can include one or more piezoelectric actuators. In the illustrated example, the second valve actuator 1228 includes two piezoelectric actuators 1288a, 1288b. Each piezoelectric actuator 1288a, 1288b can deform axially in response to an applied electric field (e.g., an applied voltage or current). The combined axial deformation of the piezoelectric actuators 1288a, 1288b can translate into axial movement of the second valve plug 1206 within the chamber portion 1208b. In one example, each piezoelectric actuator 1288a, 1288b can be an amplified piezoelectric actuator including a piezoelectric element 1290a, 1290b mounted within a respective flexure housing 1292a, 1292b. The flexure housings 1292a, 1292b can be coupled to one another (e.g., using a threaded pin 1294). The second valve plug 1206 can be coupled to an adjacent piezo actuator 1288a (eg, using a threaded pin 1284).

[0132] When an electric field is applied to each of the piezoelectric actuators 1288a, 1288b, the respective piezoelectric actuator 1288a, 1288b expands laterally (e.g., in a direction transverse to the axial axis L2), causing the respective flexure housing 1292a, 1292b to shorten axially (e.g., in a direction parallel to the axial axis L2). The amount that each flexure housing 1292a, 1292b shortens is proportional to the electric field applied to the respective piezoelectric actuator 1288a, 1288b. The axial displacement of the second valve plug 1228 in a direction parallel to the axial axis L2 is determined by the combined amount that the flexure housings 1292, 1292 are axially shortened.

[0133] The two piezo actuators 1288a, 1288b can provide a larger stroke compared to a single piezo actuator and serve to expel fluid from the common chamber 1208 to the exhaust port 1220 through the exhaust orifice 1214. In some examples, the second valve actuator 1228 can have a single piezo actuator configured to provide a stroke sufficient to expel fluid from the common chamber 1208 to the exhaust port 1220. In some examples, the single piezo actuator can be combined with a relatively large exhaust orifice 1214 to expel fluid from the chamber 1208 to the exhaust port 1220.

[0134] In some examples, the valve cap 1234 can have an electrical feedthrough 1229 (see FIGS. 12G and 12H) that extends into the common chamber 1208 and is connected to the valve actuators 1226, 1228. The electrical feedthrough 1229 can be used to provide power to the piezo elements of the piezo actuators 1258, 1288a, 1288b.

[0135] The first valve 1203 can have a closed position in which the first valve plug 1204 abuts the tip of the delivery nozzle 1212 and the delivery orifice 1210 is closed or sealed (e.g., pad 1254 covers the delivery orifice 1210). The first valve 1203 can have an open position (or range of open positions) in which the first valve plug 1204 is lifted from the tip of the delivery nozzle 1212 and the delivery orifice 1210 is open (e.g., exposed to the common chamber 1208). When the first valve 1203 is in the open position, a delivery gap G1 (shown in FIG. 12D ) is formed between the first valve plug 1204 and the delivery orifice 1210. The size of the delivery gap G1 and the pressure of the fluid at the delivery port 1218 determine the flow rate of fluid that can flow through the delivery orifice 1210 and into the common chamber 1208. The closed position of the first valve 1203 may correspond to no electric field being applied to the piezo actuator 1258 .

[0136] The second valve 1205 can have a closed position in which the second valve plug 1206 is biased against the tip of the discharge nozzle 1216, closing or sealing the discharge orifice 1214 (e.g., the pad 1282 covers the discharge orifice). The second valve 1205 can have an open position (or range of open positions) in which the second valve plug 1206 is lifted from the tip of the discharge nozzle 1216, leaving the discharge orifice 1214 open (e.g., exposed to the common chamber 1208). When the second valve 1205 is in the open position, a discharge gap G2 is formed between the second valve plug 1206 and the discharge orifice 1214. The size of the discharge gap G2 and the pressure of the fluid in the common chamber 1208 determine the rate at which fluid flows through the discharge orifice 1214 to the discharge port 1220. The closed position of the second valve 1205 can correspond to no electric field being applied to either of the piezo actuators 1288a, 1288b.

[0137] 12C , first valve 1203 can have a stroke adjustment mechanism 1264 that allows the position of first valve plug 1204 to be adjusted after valve unit 1201 is assembled into valve manifold 1202. For example, the position of first valve plug 1204 can be adjusted so that when no electric field is applied to piezo actuator 1258, first valve plug 1204 contacts the tip of delivery nozzle 1212 and closes delivery orifice 1210.

[0138] The valve cap 1234 can have a first hole 1268 that can be axially aligned with the first hole 1244 of the manifold block 1236. The stroke adjustment mechanism 1264 can have an adjustment head 1266 housed in the first hole 1268. The adjustment head 1266 is coupled to the piezo actuator 1258 (e.g., the adjustment head 1266 can be coupled to the flexure housing 1262 of the piezo actuator 1258 by a threaded pin 1270). A sealing member (or gasket) 1272 can be disposed between the adjustment head 1266 and the wall of the first hole 1268 to prevent leakage of chamber fluid through a path between the hole 1268 and the adjustment head 1266.

[0139] The stroke adjustment mechanism 1264 can include an adjustment screw 1274 that passes through an opening 1276 in the valve cap 1234, into a first hole 1268, and then into a threaded opening 1278 in the adjustment head 1266. The adjustment screw 1274 is rotatably supported relative to the first hole 1268 by bearings 1277, 1279 and is axially constrained by a nut 1284 threaded onto the screw. As the adjustment screw 1274 is rotated, the adjustment head 1266 can move axially along the adjustment screw 1274, utilizing the threaded interface between the threaded opening 1278 and the adjustment screw 1274. The adjustment screw 1274 can be rotated until it is stopped by contact between the first valve plug 1204 and the tip of the delivery nozzle 1212.

[0140] The second valve 1205 can have a stroke adjustment mechanism 1293 that can be used to adjust the position of the second valve plug 1206 after the valve unit 1201 is assembled into the valve manifold 1202. For example, the position of the second valve plug 1206 can be adjusted so that the second valve plug 1206 contacts the tip of the discharge nozzle 1216 and closes the discharge orifice 1214 when no electric field is applied to the piezoelectric actuators 1288 a, 1288 b.

[0141] The valve cap 1234 can have a second hole 1294 axially alignable with the second hole 1246 of the manifold block 1236. The stroke adjustment mechanism 1293 can have an adjustment head 1295 housed in the second hole 1293. The adjustment head 1295 is coupled to the piezo actuator 1288b (e.g., the adjustment head 1295 can be coupled to the flexure housing 1292b using a threaded pin 1296). A sealing member (or gasket) 1297 can be disposed between the adjustment head 1295 and the wall of the second hole 1294 to prevent leakage of chamber fluid through a path between the hole 1292 and the adjustment head 1295.

[0142] The stroke adjustment mechanism 1293 can have an adjustment screw 1298 that passes through an opening 1299 in the valve cap 1234, into a second hole 1294, and then into a threaded opening 1281 in the adjustment head 1295. The adjustment screw 1298 is rotatably supported relative to the second hole 1294 by bearings 1283, 1285 and is axially constrained by a nut 1287 threaded onto the screw. As the adjustment screw 1298 is rotated, the adjustment head 1295 can move axially along the adjustment screw 1298 using the threaded interface between the threaded opening 1281 and the adjustment screw 1298. The adjustment screw 1298 can be rotated until it stops when the second valve plug 1206 contacts the tip of the discharge nozzle 1216.

[0143] When the valve 1200 is initially assembled, while no electric field is applied to the piezoelectric actuators 1258, 1288a, 1288b, the valve plugs 1204, 1206 can be offset (or axially displaced) from the respective tips of the nozzles 1212, 1216, such that the supply orifice 1210 and the exhaust orifice 1214 open to a common chamber 1208, as shown in FIG. 12F. The supply port 1218 can be connected to a fluid source (e.g., accumulator 1302 in FIG. 13), and the exhaust port 1218 can be connected to a fluid return (e.g., reservoir 1314 in FIG. 13). Pressurized fluid introduced into the supply port 1218 enters and fills the chamber 1208 through the supply orifice 1210. At this stage, the second valve plug 1206 is offset from the discharge nozzle 1216, so that fluid is discharged from the chamber 1208 through the discharge orifice 1214 to the discharge port 1220. The filling rate of the chamber 1208 can be faster than the rate at which fluid is discharged from the chamber 1208.

[0144] After filling chamber 1208 with fluid from supply port 1218, with no electric field applied to piezo actuator 1258, stroke adjustment mechanism 1264 can be operated to move first valve plug 1204 to a position where it contacts the tip of supply nozzle 1212 and seals or closes supply orifice 1210. With no electric field applied to piezo actuators 1288a, 1288b, stroke adjustment mechanism 1293 can be operated to move second valve plug 1206 to a position where it contacts the tip of exhaust nozzle 1216 and seals or closes exhaust orifice 1214. After these adjustments, an electric field can be selectively applied to the piezoelectric actuators 1258, 1288a, 1288b to displace the valve plugs 1204, 1206 from the respective nozzles 1212, 1216 and open the respective orifices 1210, 1214.

[0145] The valve unit 1201 can have an intake stroke and an exhaust stroke. During the intake stroke, the valve unit 1201 can receive pressurized fluid in a common chamber 1208. If the valve unit 1201 is connected to a hydraulic actuator, the pressurized fluid in the common chamber 1208 can be supplied to the hydraulic actuator through a metering port 1222 of the valve unit 1201. During the exhaust stroke, the fluid can be exhausted from the common chamber 1208. The stroke cycle can be repeated as necessary to operate the hydraulic actuator.

[0146] The intake stroke of the valve unit 1201 can include opening the supply orifice 1210 (e.g., controlling the first valve 1203 to an open position) and closing the exhaust orifice 1214 (e.g., controlling the second valve 1205 to a closed position). Pressurized fluid received at the supply port 1218 of the valve manifold can enter the common chamber 1208 and fill the chamber 1208 (see FIG. 12D). The rate at which the fluid enters the chamber 1208 depends on the size of the supply gap G1 between the first valve plug 1204 and the tip of the supply nozzle 1212 (or supply orifice 1210) and the pressure of the fluid. The magnitude of the electric field applied to the piezo actuator 1258 determines the size of the supply gap G1. In some examples, the supply gap can be in the range of 65 to 70 microns. The fluid received at the common chamber 1208 can exit the common chamber 1208 through the metering port 1222. The supply gap in some examples can accommodate a maximum flow rate of 0.29 LPM at the metering port.

[0147] The discharge stroke of the valve unit 1201 can include closing the supply orifice 1210 (e.g., controlling the first valve 1203 to a closed position) and opening the discharge orifice 1214 (e.g., controlling the second valve 1205 to an open position). The supply orifice 1210 can be controlled, for example, by turning off the electric field applied to the piezoelectric actuator 1258, causing the first valve plug 1204 to return to a position where it contacts the tip of the supply nozzle 1212 and seals the supply orifice 1210. The second orifice 1214 can be controlled by applying an electric field to the piezoelectric actuators 1288a, 1288b to axially displace the second valve plug 1206 from the discharge nozzle 1216, thereby forming a discharge gap G2 between the second valve plug 1206 and the tip of the discharge nozzle 1216 (or discharge orifice 1214). The magnitude of the electric field applied to the piezoelectric actuators 1288a, 1288b determines the size of the exhaust gap G2. In some examples, the exhaust gap can be in the range of 130 to 140 microns. Fluid in the common chamber 1208 can exit through the exhaust gap and the exhaust orifice 1214 to the exhaust port 1220.

[0148] 12G and 12H, in some examples, the metering port 1222 can be an opening in a valve cap 1234 that extends to the common chamber 1208 and has a pipe fitting 1223 attached. Hydraulic lines (e.g., hoses) for hydraulic actuators can be connected to the pipe fitting 1223. In some examples, a pressure transducer 1225 and associated measurement circuitry can be attached to the valve cap 1234. The valve cap 1234 can have a channel 1230 that extends from the pressure transducer 1225 to the common chamber 1208 and allows the pressure transducer 1225 to sense pressure changes in the common chamber 1208.

[0149] The pressure transducer 1225, together with the piezoelectric actuators 1258, 1288a, and 1288b, enable impedance control of the force acting on the hydraulic actuators fluidly connected to the metering port 1222. For example, pressure measurements by the pressure transducer 1225 indicate the pressure in the common chamber 1208. This pressure is identical to the pressure in the fluid line (e.g., fluid line 1320 in FIG. 13) connecting the hydraulic actuators to the metering port 1222. The pressure measurements can be used to determine the force applied to the output of the hydraulic actuators and used for impedance control. The valve unit 1201 functions as a proportional valve because the supply gap G1 between the supply orifice 1210 and the first valve plug 1204 can be varied by small increments through control of the electric field applied to the piezoelectric actuator 1258.

[0150] 14A and 14B, an electrohydraulic valve 1400 can have two valve units 1401a and 1401b disposed on opposite sides of a valve manifold 1402. Each of the valve units 1401a, 1401b can include any of the features and functionality described for the valve unit 1201 (FIGS. 12A-12H). The valve manifold 1402 can include any of the features and functionality described for the valve manifold 1202 (FIGS. 12A-12H). For example, each of the valve units 1401a, 1401b can have a common chamber 1408a, 1408b that includes a first valve 1403a, 1403b operable to open or close a supply orifice 1410a, 1410b, and a second valve 1405a, 1405b operable to open or close a discharge orifice 1414a, 1414b. Each valve unit 1401a, 1401b can have a metering port 1422a, 1422b fluidly connected to a respective common chamber 1408a, 1408b. Each metering port 1422a, 1422b can be connected to a respective hydraulic actuator (e.g., a single-acting hydraulic cylinder), or both metering ports 1422a, 1422b can be connected to the same hydraulic actuator (e.g., a double-acting hydraulic cylinder). Each valve unit 1401a, 1401b can include a pressure transducer 1425a, 1425b for measuring the pressure in the respective common chamber 1408a, 1408b. Each valve unit 1401a, 1401b can include electrical feedthroughs for the valve actuator, stroke adjustment mechanism, and other features and functions described for valve unit 1201. The valve manifold 1402 can have a supply port 1418 fluidly connected to the supply orifices 1410a, 1410b and an exhaust port 1420 fluidly connected to the exhaust orifices 1414a, 1414b.

[0151] FIG. 14C illustrates a valve pack 1499 in which multiple electrohydraulic valves 1400 are connected in series. Three electrohydraulic valves 1400 are shown. However, the number of electrohydraulic valves 1400 that can be incorporated into the valve pack 1500 is not limited to three. Generally, the number of electrohydraulic valves 1400 that can be included in the valve pack depends on the number and type of hydraulic actuators connected to the valve pack. For example, a valve pack can be configured with a number of electrohydraulic valve assemblies sufficient to operate a robotic hand (906 in FIG. 9), which can have a combination of single-acting and double-acting hydraulic cylinders to control its degrees of freedom. The electrohydraulic valves 1400 can be connected to each other using flange members 1437 of the valve manifold 1402.

[0152] FIG. 15 is a simplified circuit diagram illustrating an example of a hydraulic system 1500 that uses an electro-hydraulic valve 1400 to supply fluid to a double-acting hydraulic cylinder 1512. A valve manifold supply port 1418 (fluidly connected to supply orifices 1410a, 1410b as shown in FIG. 14B) can be fluidly connected to an accumulator 1502 through a main manifold 1518. The accumulator 1502 receives pressurized fluid (e.g., oil) from a pump 1504 having a suction end fluidly connected to a reservoir 1514. The hydraulic fluid from the pump 1504 to the accumulator 1502 can pass through a directional valve 1516, a high-pressure filter 1506, a check valve 1508, and the main manifold 1518. The hydraulic system 1500 can have a dump valve 1510 fluidly connected to the reservoir 1514. The dump valve 1510 can vent pressure in the accumulator 1502 when the hydraulic system is turned off. Metering port 1422a of valve unit 1401a can be connected to one side of hydraulic cylinder 1512 via hydraulic line 1520a, and metering port 1422b of valve unit 1401b can be connected to the other side of hydraulic cylinder 1512 via hydraulic line 1520b. Valve manifold exhaust port 1420 (which is fluidly connected to exhaust orifices 1414a, 1414b as shown in FIG. 14B) can be fluidly connected to reservoir 1514.

[0153] Various implementations described herein are incorporated by reference in U.S. Patent Application No. 16 / 940,566 (Publication No. US2021-0031383A1), U.S. Patent Application No. 17 / 023,929 (Publication No. US2021-0090201A1), U.S. Patent Application No. 17 / 061,187 (Publication No. US2021-0122035A1), and U.S. Patent Application No. 17 / 098,716 (Publication No. US2021-0146553A1), U.S. Patent Application No. 17 / 111,789 (Publication No. US2021-0170607A1), U.S. Patent Application No. 17 / 158,244 (Publication No. US2021-0234997A1), U.S. Patent Application No. 17 / 217,650 (Publication No. US No. 2021-0307170A1), and / or U.S. Proper Patent Application No. 17 / 386,877, as well as some or all of the systems, devices, and methods described in U.S. Proper Patent Application No. 17 / 749,536, U.S. Proper Patent Application No. 17 / 833,998, U.S. Proper Patent Application No. 17 / 863,333, U.S. Proper Patent Application No. 17 / 867,056, U.S. Proper Patent Application No. 17 / 871,801, U.S. Proper Patent Application No. 17 / 976,665, and / or U.S. Provisional Patent Application No. 63 / 342,414, each of which is incorporated by reference herein in its entirety.

[0154] Throughout this specification and the appended claims, infinitive verb forms are frequently used. Examples include, but are not limited to, "provide," "control," etc. Unless the specific context requires otherwise, these infinitive forms are used in an open and inclusive sense to be interpreted as "at least provide," "at least control," etc.

[0155] The present specification, including the drawings and abstract, is not intended to be an exhaustive or limiting description of all implementations and embodiments of the present systems, devices, and methods. Those skilled in the art will appreciate that the various descriptions and drawings set forth herein may be modified without departing from the spirit and scope of the present disclosure. In particular, the teachings herein are not intended to be limited by or to the illustrative examples of robotic systems and hydraulic circuits provided.

[0156] The claims of the present disclosure are as follows. This disclosure is intended to support, enable, and illustrate the claims, but is not intended to limit the claims to any particular implementation or embodiment. In general, the claims should be construed to include all possible implementations and embodiments, along with the full range of equivalents to which such claims are entitled. Additional Examples

[0157] Additional embodiments based on the principles described herein are listed below. Additional embodiments within the scope of the present subject matter may be constructed, for example, by employing a single feature of an embodiment alone, by employing multiple features of an embodiment in combination, or by combining one or more features of an embodiment with one or more features of one or more other embodiments.

[0158] Example 1: A compact hydraulic valve includes a valve body having a supply port and an outlet port; a fluid path through the valve body capable of hydraulically connecting the supply port and the outlet port and having a nozzle with a diameter in a first range of 600 micrometers to 700 micrometers; a plunger disposed in the fluid path near the nozzle; and a piezoelectric material in mechanical communication with the plunger, the position of the plunger relative to the nozzle being dependent on at least one dimension of the piezoelectric material, the at least one dimension of the piezoelectric material being responsive to one or more electrical signals from an electrical system. In operation, when the electrical system does not supply power to the piezoelectric material, the plunger is biased against the nozzle to block the flow of hydraulic fluid along the fluid path. This bias is sufficient to block the flow at a fluid pressure of at least 700 pounds per square inch (psi). In operation, when the electrical system supplies power to the piezoelectric material, the plunger is displaced from the nozzle to form a gap between the plunger and the nozzle, allowing hydraulic fluid to flow along the fluid path. The gap is proportional to the power supplied to the piezoelectric material, and the plunger displacement is in the second range of 40 to 70 micrometers. The gap can accommodate hydraulic fluid flow rates up to 0.5 liters per minute (lpm).

[0159] Example 2: The compact hydraulic valve of Example 1, wherein the valve body includes or is fabricated from aluminum.

[0160] Example 3: The compact hydraulic valve of Example 1, wherein the valve body is cylindrical.

[0161] Example 4: The miniature hydraulic valve of example 3, wherein at least a portion of the volume of the piezoelectric material is a cylindrical sleeve.

[0162] Example 5: The compact hydraulic valve of example 1, wherein at least a portion of the valve body is formed by one of assembling multiple elements, casting, molding, 3D printing, or machining from a solid cylinder.

[0163] Example 6: The small hydraulic valve of Example 1, wherein the hydraulic fluid is oil.

[0164] Example 7: The miniature hydraulic valve of Example 6, wherein the oil is peanut oil having a viscosity in the range of 60 centistokes to 80 centistokes.

[0165] Example 8: The compact hydraulic valve of Example 1, wherein the supply and outlet ports each have a respective through hole capable of receiving a hydraulic fitting fluidly connectable to a hydraulic hose.

[0166] Example 9: The compact hydraulic valve of example 1, wherein the plunger has a gasket, and wherein biasing the plunger against the nozzle to block the flow of hydraulic fluid along the fluid path comprises biasing the gasket against the nozzle.

[0167] Example 10: The miniature hydraulic valve of Example 9, wherein the gasket comprises polytetrafluoroethylene (PTFE).

[0168] Example 11: The miniature hydraulic valve of example 1, wherein the electrical system is operable to receive an electrical signal to electrically actuate the piezoelectric material to open the aperture.

[0169] Example 12: The miniature hydraulic valve of example 11, wherein the electrically controlled actuation of the piezoelectric material comprises elongation of the piezoelectric material.

[0170] Example 13: The miniature hydraulic valve of example 11, wherein the electrically controlled actuation of the piezoelectric material comprises contraction of the piezoelectric material.

[0171] Example 14: The miniature hydraulic valve of Example 13, where the contraction of the piezoelectric material is amplified.

[0172] Example 15: The miniature hydraulic valve of Example 14, wherein the piezoelectric material is an ellipsoid.

[0173] Example 16: The miniature hydraulic valve of Example 1, wherein the piezoelectric material comprises lead zirconate titanate.

[0174] Example 17: A hydraulic system includes a compact hydraulic valve having a valve body with a supply port and an outlet port; a fluid path through the valve body capable of hydraulically connecting the supply port and the outlet port and having a nozzle with a diameter in a first range of 600 micrometers to 700 micrometers; a plunger disposed in the fluid path near the nozzle; a piezoelectric material in mechanical communication with the plunger; and an electrical system electrically and communicatively connected to the piezoelectric material, wherein at least one dimension of the piezoelectric material is responsive to one or more electrical signals from the electrical system, and the position of the plunger relative to the nozzle is dependent on the at least one dimension of the piezoelectric material. During operation, when the electrical system does not supply power to the piezoelectric material, the plunger is biased against the nozzle, blocking the flow of hydraulic fluid along the fluid path. This bias is sufficient to block the flow at a fluid pressure of at least 700 pounds per square inch (psi). During operation, when the electrical system supplies power to the piezoelectric material, the plunger is displaced from the nozzle, forming a gap between the plunger and the nozzle, allowing hydraulic fluid to flow along the fluid path. This gap is proportional to the power supplied to the piezoelectric material, and the plunger displacement is in the second range of 40 to 70 micrometers. The gap is sufficient to accommodate hydraulic fluid flow rates up to 0.5 liters per minute (lpm).

[0175] Example 18: The hydraulic system of Example 17, further comprising a hydraulic pump, an accumulator, a reservoir, and at least one hydraulic hose.

[0176] Example 19: The hydraulic system of example 17, wherein the valve body includes or is fabricated from aluminum.

[0177] Example 20: The hydraulic system of Example 17, wherein the valve body is cylindrical.

[0178] Example 21: The hydraulic system of example 20, wherein at least a portion of the volume of the piezoelectric material is a cylindrical sleeve.

[0179] Example 22: The hydraulic system of example 17, wherein at least a portion of the valve body is formed by one of a multi-component assembly, casting, molding, 3D printing, or machining from a solid cylinder.

[0180] Example 23: The hydraulic system of Example 17, wherein the hydraulic fluid is oil.

[0181] Example 24: The hydraulic system of Example 23, wherein the oil is peanut oil having a viscosity in the range of 60 centistokes to 80 centistokes.

[0182] Example 25: The hydraulic system of example 17, wherein the supply and outlet each have a respective through-hole capable of receiving a hydraulic fitting fluidly connectable to a hydraulic hose.

[0183] Example 26: The hydraulic system of example 17, wherein the plunger includes a gasket, and wherein biasing the plunger against the nozzle to block the flow of hydraulic fluid along the fluid path comprises biasing the gasket against the nozzle.

[0184] Example 27: The hydraulic system of Example 26, wherein the gasket comprises polytetrafluoroethylene (PTFE).

[0185] Example 28: The hydraulic system of example 17, wherein the electrical system is operable to receive an electrical signal to electrically control and actuate the piezoelectric material to open the aperture.

[0186] Example 29: The hydraulic system of example 28, wherein the electrically controlled actuation of the piezoelectric material comprises elongation of the piezoelectric material.

[0187] Example 30: The hydraulic system of example 28, wherein the electrically controlled actuation of the piezoelectric material comprises contraction of the piezoelectric material.

[0188] Example 31: The hydraulic system of example 30, wherein the contraction of the piezoelectric material is amplified.

[0189] Example 32: The hydraulic system of example 31, wherein the piezoelectric material is an ellipsoid.

[0190] Example 33: The hydraulic system of example 17, wherein the piezoelectric material comprises lead zirconate titanate.

[0191] Example 34: A robotic arm includes a hydraulic control system physically coupled to the robot body, a hydraulic actuation component physically coupled to the robot body and capable of manipulating at least a portion of the robot, and a hydraulic assembly including a miniature hydraulic valve. The hydraulic assembly includes a miniature hydraulic valve. The miniature hydraulic valve includes a valve body having an inlet and an outlet, a fluid path through the valve body capable of hydraulically communicating the inlet and the outlet and having a nozzle with a diameter in a first range of 600 micrometers to 700 micrometers, a plunger disposed in the fluid path near the nozzle, a piezoelectric material in mechanical communication with the plunger, and an electrical system electrically and communicatively connected to the piezoelectric material, wherein at least one dimension of the piezoelectric material is responsive to one or more electrical signals from the electrical system, and the position of the plunger relative to the nozzle is dependent on at least one dimension of the piezoelectric material. During operation, when the electrical system does not supply power to the piezoelectric material, the plunger is biased against the nozzle, blocking the flow of hydraulic fluid along the fluid path. This bias is sufficient to block flow at fluid pressures of at least 700 pounds per square inch (psi). In operation, when an electrical system supplies power to the piezoelectric material, the plunger displaces from the nozzle, creating a gap between the plunger and the nozzle, allowing hydraulic fluid to flow along the fluid path. This gap is proportional to the power supplied to the piezoelectric material, and the plunger displacement is in the second range of 40 micrometers to 70 micrometers. The gap can accommodate hydraulic fluid flow rates up to 0.5 liters per minute (lpm).

[0192] Example 35: The robotic arm of example 34, wherein the valve body comprises or is fabricated from aluminum.

[0193] Example 36: The robot arm of example 34, wherein the valve body is cylindrical.

[0194] Example 37: The robotic arm of example 36, wherein at least a portion of the volume of the piezoelectric material is a cylindrical sleeve.

[0195] Example 38: The robotic arm of example 34, wherein at least a portion of the valve body is formed by either assembly of multiple elements, casting, molding, 3D printing, or machining from a solid cylinder.

[0196] Example 39: The robot arm of example 34, wherein the hydraulic fluid is oil.

[0197] Example 40: The robotic arm of Example 39, wherein the oil is peanut oil having a viscosity in the range of 60 centistokes to 80 centistokes.

[0198] Example 41: The robotic arm of example 34, wherein each of the supply and discharge ports includes a through hole capable of accommodating a hydraulic fitting fluidly connectable to a hydraulic hose.

[0199] Example 42: The robot arm of example 34, wherein the plunger includes a gasket, and wherein forcing the plunger against the nozzle to block the flow of hydraulic fluid along the fluid path includes forcing the gasket against the nozzle.

[0200] Example 43: The robotic arm of example 42, wherein the gasket comprises polytetrafluoroethylene (PTFE).

[0201] Example 44: The robotic arm of example 34, wherein the electrical system is operable to receive an electrical signal that electrically controls and activates the piezoelectric material to open the aperture.

[0202] Example 45: The robotic arm of example 44, wherein the electrically controlled actuation of the piezoelectric material comprises elongation of the piezoelectric material.

[0203] Example 46: The robotic arm of example 44, wherein the electrically controlled actuation of the piezoelectric material comprises contraction of the piezoelectric material.

[0204] Example 47: The robot arm of example 46, wherein the contraction of the piezoelectric material is amplified.

[0205] Example 48: The robot arm of Example 47, wherein the piezoelectric material is an ellipsoid.

[0206] Example 49: The robotic arm of example 34, wherein the piezoelectric material comprises lead zirconate titanate.

[0207] Example 50: A robot includes a robot body, a hydraulic control system physically coupled to the robot body, a hydraulic actuation component physically coupled to the robot body and operable to cause movement of at least a portion of the robot, and a hydraulic assembly having a miniature hydraulic valve. The miniature hydraulic valve includes a valve body having an inlet and an outlet, a fluid path through the valve body capable of hydraulically communicating the inlet and the outlet and having a nozzle with a diameter in a first range of 600 micrometers to 700 micrometers, a plunger disposed in the fluid path near the nozzle, a piezoelectric material in mechanical communication with the plunger, and an electrical system electrically and communicatively connected to the piezoelectric material, wherein at least one dimension of the piezoelectric material is responsive to one or more electrical signals from the electrical system, and the position of the plunger relative to the nozzle is dependent on the at least one dimension of the piezoelectric material. In operation, when the electrical system does not supply power to the piezoelectric material, the plunger is biased against the nozzle, blocking the flow of hydraulic fluid along the fluid path. This bias is sufficient to block flow at fluid pressures of at least 700 pounds per square inch (psi). In operation, when an electrical system supplies power to the piezoelectric material, the plunger displaces from the nozzle, creating a gap between the plunger and the nozzle, allowing hydraulic fluid to flow along the fluid path. The gap is proportional to the power supplied to the piezoelectric material, and the plunger displacement is in the range of 40 micrometers to 70 micrometers. The gap can accommodate hydraulic fluid flow rates of up to 0.5 liters per minute (lpm).

[0208] Example 51: The robot of example 50, wherein the valve body includes or is manufactured from aluminum.

[0209] Example 52: The robot of example 50, wherein the valve body is cylindrical.

[0210] Example 53: The robot of Example 52, wherein at least a portion of the volume of the piezoelectric material is a cylindrical sleeve.

[0211] Example 54: The robot of example 50, wherein at least a portion of the valve body is formed by assembling multiple elements, casting, molding, 3D printing, or machining from a solid cylinder.

[0212] Example 55: The robot of Example 50, wherein the hydraulic fluid is oil.

[0213] Example 56: The robot of Example 55, wherein the oil is peanut oil having a viscosity in the range of 60 centistokes to 80 centistokes.

[0214] Example 57: The robot of example 50, wherein each of the supply and discharge ports has a respective through-hole capable of accommodating a hydraulic coupling that is fluidly connectable to a hydraulic hose.

[0215] Example 58: The robot of Example 50, wherein the plunger includes a gasket, and wherein forcing the plunger against the nozzle to block the flow of hydraulic fluid along the fluid path includes forcing the gasket against the nozzle.

[0216] Example 59: The robot of Example 58, wherein the gasket comprises polytetrafluoroethylene (PTFE).

[0217] Example 60: The robot of Example 50, wherein the electrical system is operable to receive an electrical signal that electrically controls and activates the piezoelectric material to open the aperture.

[0218] Example 61: The robot of Example 60, wherein the electrically controlled actuation of the piezoelectric material comprises elongation of the piezoelectric material.

[0219] Example 62: The robot of Example 60, wherein the electrically controlled actuation of the piezoelectric material includes contraction of the piezoelectric material.

[0220] Example 63: The robot of Example 62, wherein the contraction of the piezoelectric material is amplified.

[0221] Example 64: The robot of Example 63, wherein the piezoelectric material is an ellipsoid.

[0222] Example 65: The robot of example 50, wherein the piezoelectric material comprises lead zirconate titanate.

[0223] Example 66: An electrohydraulic valve includes a valve manifold having a supply port and an exhaust port, a valve housing defining a common chamber, a metering port communicating with the common chamber, and a first end coupled to the valve manifold, a first nozzle in fluid communication with the supply port and disposed within the common chamber, the first nozzle having a first nozzle tip with a first orifice, a second nozzle in fluid communication with the exhaust port and disposed within the common chamber, the second nozzle having a second nozzle tip with a second orifice, a first valve plug disposed within the common chamber and opposite the first orifice, and a first valve plug coupled to the first valve plug, the first valve plug contacting the first nozzle tip to close the first orifice, and the first valve plug being offset from the first nozzle tip; a first valve actuator operable to move the first valve plug between an open position, in which a first gap is formed between the first valve plug and the first orifice, allowing fluid to pass from the first orifice to the common chamber; a second valve plug disposed in the common chamber and positioned opposite the second orifice; and a second valve actuator coupled to the second valve plug and operable to move the second valve plug between a closed position, in which the second valve plug contacts the second nozzle tip and closes the second orifice, and an open position, in which the second valve plug is offset from the second nozzle tip and a second gap is formed between the second valve plug and the second orifice, allowing fluid to pass from the common chamber to the second orifice.

[0224] Example 67: An electrohydraulic valve according to Example 66, wherein the first valve actuator comprises a first piezoelectric actuator having a first piezoelectric element and a first flexure element, and the first flexure element is coupled to the first valve plug.

[0225] Example 68: An electrohydraulic valve according to Example 67, wherein the second valve actuator includes a second piezoelectric actuator having a second piezoelectric element and a second flexure element, and the second flexure element is coupled to the second valve plug.

[0226] Example 69: An electrohydraulic valve according to Example 68, wherein the second valve actuator has a third piezoelectric actuator having a third piezoelectric element and a third flexure element, and the third flexure element is coupled to the second flexure element.

[0227] Example 70: An electrohydraulic valve according to Example 66, wherein the valve housing has a valve body portion in which the common chamber is defined and a valve cap portion surrounding one end of the common chamber.

[0228] Example 71: An electrohydraulic valve according to Example 70, further comprising a first stroke adjustment mechanism coupled to the first valve plug and operable to adjust the position of the first valve plug relative to the first nozzle tip, and a second stroke adjustment mechanism coupled to the second valve plug and operable to adjust the position of the second valve plug relative to the second nozzle tip.

[0229] Example 72: An electrohydraulic valve according to Example 71, wherein the first stroke adjustment mechanism has a first adjustment head connected to the first valve plug and a first adjustment screw threadably connected to the first adjustment head, and rotation of the first adjustment screw causes the first adjustment head to translate along the first adjustment screw.

[0230] Example 73: An electrohydraulic valve according to Example 72, wherein the first adjusting screw is rotatably coupled to the valve cap and axially constrained relative to the valve cap.

[0231] Example 74: An electrohydraulic valve according to Example 72, wherein the first valve actuator comprises a first piezoelectric actuator having a first piezoelectric element and a first flexure element, the first flexure element being coupled at a first end to a first valve plug and at a second end to a first adjusting head.

[0232] Example 75: An electrohydraulic valve according to Example 72, wherein the second stroke adjustment mechanism has a second adjustment head connected to the second valve plug and a second adjustment screw threadably connected to the second adjustment head, and rotation of the second adjustment screw causes the second adjustment head to move in translation along the second adjustment screw.

[0233] Example 76: An electrohydraulic valve according to Example 75, wherein the second adjusting screw is rotatably coupled to the valve cap and axially constrained relative to the valve cap.

[0234] Example 77: An electrohydraulic valve according to Example 75, wherein the second valve actuator has at least one piezoelectric actuator having a piezoelectric element and a flexure element, the flexure element being coupled to the second valve plug on a first side and coupled to the second adjusting head on a second side.

[0235] Example 78: An electrohydraulic valve according to Example 75, wherein the second valve actuator has a first piezoelectric actuator having a first piezoelectric element and a first flexure element, the second valve actuator has a second piezoelectric actuator having a second piezoelectric element and a second flexure element, the first flexure element being connected to the second valve plug on a first side and to the first side of the second flexure element on a second side, and the second flexure element being connected to the second adjustment head on a second side.

[0236] Example 79: An electrohydraulic valve according to Example 75, wherein the first adjusting head is accommodated within a first hole formed in the valve cap portion and is movable axially within the first hole in response to rotation of the first adjusting screw, and the second adjusting head is accommodated within a second hole formed in the valve cap portion and is movable axially within the second hole in response to rotation of the first adjusting screw.

[0237] Example 80: An electrohydraulic valve as described in Example 70, further comprising a pressure transducer coupled to the valve cap portion and an opening in the valve cap portion forming a pressure transmission path between the pressure transducer and the common chamber.

[0238] Example 81: An electrohydraulic valve as described in Example 70, further comprising an electrical feedthrough coupled to the valve cap portion and electrically connected to the first valve actuator and the second valve actuator within the common chamber.

[0239] Example 82: An electrohydraulic valve as described in Example 81, wherein the metering port is formed in the valve cap portion and has a fitting for connecting a hydraulic line.

[0240] Example 83: An electrohydraulic valve according to Example 66, wherein the valve manifold has a first hole connected to the supply port and a second hole connected to the exhaust port, the first nozzle is mounted within the first hole with the first nozzle tip protruding into the common chamber, and the second nozzle is mounted within the second hole with the second nozzle tip protruding into the common chamber.

[0241] Example 84: An electrohydraulic valve according to Example 66, wherein a portion of the first valve plug positioned opposite the first orifice has a first sealing member, and a portion of the second valve plug positioned opposite the second orifice has a second sealing member.

[0242] Example 85: A method of operating a hydraulic actuator includes applying an electric field to a first valve actuator disposed in a common chamber of a valve unit to axially displace a first valve plug disposed in the common chamber from a first orifice connected to a supply port of a valve manifold, thereby forming a first communication path between the supply port and the common chamber through the first orifice; supplying fluid from a fluid source connected to the supply port to the common chamber through the first communication path; and supplying the fluid from the common chamber to the hydraulic actuator through a metering port of the valve unit. removing an electric field from a first valve actuator to urge the first valve plug against the first orifice to close the first communication path; applying an electric field to a second valve actuator disposed in the common chamber of the valve unit to axially displace a second valve plug disposed in the common chamber from a second orifice connected to an exhaust port of the valve manifold to form a second communication path between the exhaust port and the common chamber through the second orifice; and exhausting fluid from the common chamber through the second communication path to a fluid return connected to the exhaust port.

Claims

1. a valve manifold having a supply port and an exhaust port; a valve housing defining a common chamber, the valve housing having a metering port in communication with the common chamber and a first end coupled to the valve manifold; a first nozzle disposed within the common chamber in fluid communication with the supply port, the first nozzle having a first nozzle tip with a first orifice; a second nozzle disposed within the common chamber in fluid communication with the exhaust port, the second nozzle having a second nozzle tip with a second orifice; a first valve plug disposed within the common chamber and facing the first orifice; a first valve actuator coupled to the first valve plug and operable to move the first valve plug between a closed position in which the first valve plug contacts the first nozzle tip to close the first orifice and an open position in which the first valve plug is offset from the first nozzle tip to form a first gap between the first valve plug and the first orifice to allow fluid to pass from the first orifice to the common chamber; a second valve plug disposed within the common chamber and facing the second orifice; a second valve actuator coupled to the second valve plug and operable to move the second valve plug between a closed position in which the second valve plug contacts the second nozzle tip to close the second orifice and an open position in which the second valve plug is offset from the second nozzle tip to form a second gap between the second valve plug and the second orifice to allow fluid to pass from the common chamber to the second orifice; Electro-hydraulic valve comprising:

2. 2. The electrohydraulic valve of claim 1, wherein the first valve actuator comprises a first piezoelectric actuator having a first piezoelectric element and a first flexure element, the first flexure element coupled to the first valve plug.

3. 3. The electrohydraulic valve of claim 2, wherein the second valve actuator comprises a second piezoelectric actuator having a second piezoelectric element and a second flexure element, the second flexure element coupled to the second valve plug.

4. 4. The electrohydraulic valve of claim 3, wherein the second valve actuator comprises a third piezoelectric actuator having a third piezoelectric element and a third flexure element, the third flexure element coupled to the second flexure element.

5. 2. The electrohydraulic valve of claim 1, wherein the valve housing includes a valve body portion defining the common chamber and a valve cap portion surrounding one end of the common chamber.

6. a first stroke adjustment mechanism coupled to the first valve plug and operable to adjust the position of the first valve plug relative to the first nozzle tip; a second stroke adjustment mechanism coupled to the second valve plug and operable to adjust the position of the second valve plug relative to the second nozzle tip; The electrohydraulic valve of claim 5 further comprising:

7. 7. The electrohydraulic valve of claim 6, wherein the first stroke adjustment mechanism includes a first adjusting head connected to the first valve plug and a first adjusting screw threadably connected to the first adjusting head, and wherein rotation of the first adjusting screw causes translational movement of the first adjusting head along the first adjusting screw.

8. The electrohydraulic valve of claim 7 , wherein the first adjustment screw is rotatably coupled to the valve cap and axially constrained relative to the valve cap.

9. 8. The electrohydraulic valve of claim 7, wherein the first valve actuator comprises a first piezoelectric actuator having a first piezoelectric element and a first flexure element, the first flexure element coupled at a first end to a first valve plug and at a second end to a first adjusting head.

10. 8. The electrohydraulic valve of claim 7, wherein the second stroke adjustment mechanism includes a second adjustment head connected to the second valve plug and a second adjustment screw threadably connected to the second adjustment head, and wherein rotation of the second adjustment screw causes the second adjustment head to translate along the second adjustment screw.

11. The electrohydraulic valve of claim 10 , wherein the second adjustment screw is rotatably coupled to the valve cap and axially constrained relative to the valve cap.

12. 11. The electrohydraulic valve of claim 10, wherein the second valve actuator comprises at least one piezoelectric actuator having a piezoelectric element and a flexure element, the flexure element coupled on a first side to the second valve plug and coupled on a second side to the second adjusting head.

13. the second valve actuator includes a first piezoelectric actuator having a first piezoelectric element and a first flexure element; the second valve actuator includes a second piezoelectric actuator having a second piezoelectric element and a second flexure element; the first flexure element is coupled on a first side to the second valve plug and on a second side to the first side of a second flexure element; The electrohydraulic valve of claim 10 , wherein the second flexure element is coupled on a second side to the second adjustment head.

14. the first adjustment head is accommodated in a first hole formed in the valve cap portion and is axially movable within the first hole in response to rotation of the first adjustment screw; 11. The electrohydraulic valve of claim 10, wherein the second adjusting head is received within a second bore formed in the valve cap portion and is axially movable within the second bore in response to rotation of the first adjusting screw.

15. 6. The electrohydraulic valve of claim 5, further comprising a pressure transducer coupled to the valve cap portion and an opening in the valve cap portion forming a pressure transmission path between the pressure transducer and the common chamber.

16. 6. The electrohydraulic valve of claim 5, further comprising an electrical feedthrough coupled to the valve cap portion and electrically connected to the first valve actuator and the second valve actuator within the common chamber.

17. 17. The electrohydraulic valve of claim 16, wherein the metering port is formed in the valve cap portion and has a fitting for connecting a hydraulic line.

18. 2. The electrohydraulic valve of claim 1, wherein the valve manifold has a first hole connected to the supply port and a second hole connected to the exhaust port, the first nozzle mounted in the first hole with the first nozzle tip protruding into the common chamber, and the second nozzle mounted in the second hole with the second nozzle tip protruding into the common chamber.

19. 2. The electrohydraulic valve of claim 1, wherein a portion of the first valve plug positioned opposite the first orifice includes a first sealing member, and a portion of the second valve plug positioned opposite the second orifice includes a second sealing member.

20. applying an electric field to a first valve actuator disposed in a common chamber of the valve unit to axially displace a first valve plug disposed in the common chamber from a first orifice connected to a supply port of a valve manifold, thereby forming a first communication path between the supply port and the common chamber via the first orifice; supplying fluid from a fluid source connected to the supply port to the common chamber through the first communication path; supplying the fluid from the common chamber to a hydraulic actuator through a metering port of the valve unit; removing the electric field from the first valve actuator to bias the first valve plug against the first orifice to close the first communication path; applying an electric field to a second valve actuator disposed in the common chamber of the valve unit to axially displace a second valve plug disposed in the common chamber from a second orifice connected to an exhaust port of the valve manifold, thereby forming a second communication path between the exhaust port and the common chamber through the second orifice; Discharging fluid from the common chamber through the second communication path to a fluid return connected to the discharge port; A method for operating a hydraulic actuator, comprising:

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