Belt-driven linear actuator including self-alignment system and method of operating linear actuator

Abstract

This disclosure describes techniques for a self-alignment system within a belt driven linear actuator that enables a'keyless' or'round blunt profile 'piston to be sealed while maintaining alignment and / or anti-torque capability. This allows the air gap within the electromechanical actuator to be pressurized to perform an auxiliary load holding function redundant with respect to the linear screw arrangement.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to a self-aligning, belt-driven linear actuator that includes a pneumatic back-up operation function. BACKGROUND

[0002] Modern belts have many desirable properties. They can be lightweight, low maintenance, and have high strength under tension. Many new and old applications for modern belts are currently being adopted. Linear actuators are often used to manipulate sensitive, heavy, or dangerous loads. Emergency holding and back-up operation can be an important capability for certain applications. SUMMARY

[0003] Generally, the present disclosure relates to systems and methods for pneumatically operating and self-aligning a belt-driven linear actuator. The alignment system can include an actuator chassis having an inner surface, a travel assembly including an operating piston and an output shaft. The travel assembly can be configured to translate along a primary axis defined by a centerline of the output shaft. A roller can be rotatably coupled to the travel assembly and configured to mechanically engage the inner surface of the actuator chassis, the roller including an axis of rotation that is perpendicular to the primary axis. A first flanged sheave can be coupled to the output shaft, a second flanged sheave can be coupled to the actuator chassis, and a belt can extend between and around the first and second sheaves.

[0004] The alignment system can optionally include one or more of the following features.

[0005] In some examples, the roller engages the inner surface with a spring, and the spring is preloaded by a set screw.

[0006] In some examples, the first and second flanged sheaves operate as a pulley system configured to translate the output shaft along the axis.

[0007] In some examples, the roller has a curved surface shaped to maximize a contact area between the roller and the inner surface.

[0008] In some examples, the roller allows the output shaft and affixed components to rotate about the primary axis, with a range of rotation between 0.1 and 1 degrees per meter of travel.

[0009] In some examples, the roller is one of a plurality of rollers, and the plurality of rollers form an annular arrangement that at least partially encloses the output shaft.

[0010] The present disclosure further includes a method of operating a belt-driven linear actuator, the method including translating a travel assembly of the belt-driven linear actuator, and allowing the travel assembly to rotate about a primary axis while translating the travel assembly to maintain alignment of a belt between a first sheave and a second sheave.

[0011] The method may optionally include one or more of the following features.

[0012] In some instances, the method includes preventing rotation about a main axis when the traveling assembly is not translating. This prevention may include using one or more members fixed to the traveling assembly and mechanically engaging with the inner surface of the actuator frame via one or more preloaded springs to resist rotation in a frictional manner.

[0013] In some instances, the linear actuator includes an actuator frame with an inner surface, and the traveling assembly includes an actuating piston and an output shaft that translates along a main axis defined by a centerline of the output shaft. In some instances, the linear actuator includes a roller rotatably coupled to the traveling assembly, the roller being configured to mechanically engage with the inner surface of the actuator frame, the roller having a rotational axis perpendicular to the main axis.

[0014] In some instances, the first and second grooved wheels are flanged grooved wheels, with the first grooved wheel connected to the travel assembly and the second grooved wheel connected to the actuator frame.

[0015] This disclosure further describes a pneumatically operated belt-driven linear actuator. The system includes a pneumatically operated system and an alignment system. The pneumatically operated system includes: a proximal volume, a distal volume, an operating piston fixed to the output shaft of the linear actuator, the operating piston separating the distal and proximal volumes, and a valve configured to direct gas to either the distal or proximal volume, thereby creating a pressure differential across the operating piston. The alignment system is configured to maintain rotational alignment of the output shaft of the linear actuator and includes: an actuator frame having an inner surface, rollers rotatably coupled to a travel assembly and configured to mechanically engage the inner surface of the actuator frame. The rollers have an axis of rotation perpendicular to a principal axis defined by the centerline of the output shaft. The alignment system further includes: a first flange pulley coupled to the output shaft, a second flange pulley coupled to the actuator frame, and a flat belt extending between and around the first and second pulleys.

[0016] The system may optionally include one or more of the following features.

[0017] In some instances, the roller engages with the inner surface via a spring preloaded by a locating screw.

[0018] In some instances, the first flange groove wheel and the second flange groove wheel operate as a pulley system configured to translate the operating piston along the main axis.

[0019] In some instances, the roller has a curved surface shaped to maximize the contact area between the roller and the inner surface.

[0020] In some instances, the valve is a three-way valve, which can be selected to direct gas to either the proximal or distal volume.

[0021] In some instances, the system includes: an isolation valve configured to initiate gas flow when opened; and a controller configured to receive information relating to the operating load of the linear actuator and align the three-way valve to direct gas against that operating load. In some instances, the controller regulates the pressure provided by the isolation valve to match the pressure differential across the operating piston to the operating load.

[0022] Safety-critical applications in the off-highway heavy machinery industry typically involve linear actuators used to manipulate sensitive, heavy, or hazardous loads. These applications require not only methods to safely move the load to the desired physical state but also auxiliary methods to maintain the load in the event of damage to power transmission components or power outages. Conventional hydrodynamic systems typically include pipe rupture valves that open during normal operation and close if high flow occurs, thereby locking the cylinder and preventing further movement. This prevention occurs independently of most of the hydraulic circuit. From this locked state, fluid can then be drained via a throttle valve or pumped back into the cylinder using a backup pump, according to widely accepted engineering principles, allowing the cylinder system to be slowly and safely moved to the desired physical configuration for recovery and repair. In contrast, electromechanical actuators driven by ball screws or roller screws cannot meet this recovery requirement. While some electromechanical actuators integrate locking devices that can lock the linear screw in case of a failure in the upstream power transmission system (e.g., in the gearbox or motor), this offers limited capability for finely adjusting the actuator's output position. Typically, this requires externally applied torque directed to the linear screw's manual overrunning mechanism (e.g., via a hand crank), bypassing the main torque transmission path. This may be effective in limited situations, but the technique is not widely applicable to off-highway heavy machinery applications for several reasons, three of which will be discussed here.

[0023] First, it requires direct physical contact with the electromechanical actuator to move or change the output position. This is often impractical or impossible, depending on the actuator's location within the machine frame and whether the operator can physically access the actuator, which is still under load, within the machine's context. Even if physical access to the manual overrun position is possible, the torque required to drive the lead screw may be very high, far exceeding the ability of a single operator to generate that torque manually using hand tools, thus requiring auxiliary mechanisms to generate the torque to move the actuator position. Second, this principle applies only to machine degrees of freedom driven by a single actuator. If two actuators drive the same machine degree of freedom and share the load equally during operation, they also need to be manually operated synchronously (via manual overrun), which can be difficult or even impossible. In contrast, fluid from a set of paired hydrodynamic cylinders can be discharged simultaneously, ensuring even load distribution across the cylinders throughout the recovery process. Third, any mechanism that locks the linear lead screw is only operable if the linear lead screw itself is still functioning properly. Therefore, any failure mode that includes severe damage to the linear lead screw's load-bearing components may not be recoverable by a manual overrun mechanism.

[0024] Now, turning to the issue of angular alignment between the output shaft (also often called the piston rod) and the cylinder block in the actuator's operating environment, several facts can be stated regarding hydrodynamic cylinder blocks and electromechanical actuators. Hydrodynamic cylinder blocks contain rotationally symmetrical components (output shaft, piston head, seals, etc.) and allow arbitrary angular alignment applied to the paired working components (output shaft and cylinder block) by an external system. For example, as an excavator arm swings left and right, the clearance within the connecting rod bushing and the flexibility of the structural arm components will collectively result in a small offset (e.g., about 1 degree) in the relative angular alignment at the cylinder rod end position. This can be directly accommodated in hydrodynamic cylinder blocks with standard rod end / fork joint components, as angular rotation is allowed between the rod and the cylinder block. Alternatively, this rotation can be externalized through ball joints at either end of the device to minimize scratches on the cylinder walls and other asymmetrical load conditions.

[0025] Some electromechanical actuators driven by ball screw or roller screw mechanisms can also accommodate externally forced offsets in angular alignment, but they also have inherent requirements for response torque, which needs to be applied to the output shaft component to resist its rotation, otherwise it will freely rotate and travel. This response torque can be provided in one of three conventional ways: externally via the rod end position, externally via an anti-rotation device, or internally via an integrated anti-rotation device. The first option is highly undesirable because it requires torque from the rod end interface, which amplifies the load on the standard rod end or fork joint at that pivot position and does not allow for the integration of a standard ball joint, which rotates and moves violently during operation. The second way to transmit response torque to the output shaft component is via an external anti-rotation device, which typically takes the form of a linear guide type device that bears the torque along its length and transmits it to a linear bushing that runs parallel to the output shaft component. This solution is effective in controlled manufacturing environments, but it is highly undesirable in off-highway heavy machinery applications because it exposes additional sensitive and bulky linear guide components to the environment and occupies potentially unavailable additional space. A third way to transmit responsive torque to the output shaft is via an integrated anti-rotation device, which takes the form of a "keyed" geometry and is typically located between the driven nut and the housing of the device. This interface withstands significant torque because, neglecting friction, the responsive torque provided by the keyed interface must match the screw drive torque under steady-state operation. The advantages of this arrangement are obvious: all working parts within the electromechanical actuator are protected from environmental influences behind the master shaft seal; and since no external torque is required to the output shaft, a ball joint that can accommodate misalignment can be used at one of the actuator's two ends. However, the integrated anti-rotation device has two disadvantages. First, it increases the size of the device because the keyed geometry occupies additional space. Second, a convex or concave key feature must be present in the cross-section of the housing. The presence of a key in the cross-section does not allow for the use of a standard (circular profile) dynamic piston head seal, which would normally provide a seal between the traveling component and the housing.

[0026] The technology discussed in this disclosure describes a self-aligning system that allows a "keyless" or "circular profile" piston to be sealed while maintaining alignment and / or torque resistance. This allows the air gap within the electromechanical actuator to be pressurized to perform an auxiliary load holding function that is redundant relative to a linear screw mechanism. Overall, the disclosed device is an electromechanical linear actuator that is not driven by a ball screw or roller screw mechanism, but rather uses a flexible belt in a pulley block arrangement.

[0027] Details of one or more embodiments of the subject matter of this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, drawings, and claims. Attached Figure Description

[0028] To more clearly describe the technical solutions in the embodiments of this specification or the prior art, the accompanying drawings required for describing the embodiments or the prior art are briefly described below. Obviously, the drawings in the following description only show some embodiments of this specification, and those skilled in the art can still derive other drawings from these drawings without creative effort.

[0029] Figure 1 It is a three-dimensional view of a belt-driven linear actuator that includes pneumatic operation function.

[0030] Figure 2 yes Figure 1 A perspective view of a belt-driven linear actuator, with the outer housing removed to show specific internal components.

[0031] Figure 3 yes Figure 1 A partially cut-out side view of a belt-driven linear actuator that includes pneumatic operation functionality.

[0032] Figure 4 yes Figure 1 A three-dimensional diagram of a belt-driven linear actuator, showing the belt circuit.

[0033] Figure 5A This is a schematic diagram of a pneumatic system for pneumatically operating a belt-driven linear actuator.

[0034] Figure 5B It shows Figure 5A The alternative supply layout for pneumatic systems.

[0035] Figure 5C This is a schematic diagram of a pneumatic system for pneumatically operating a single-acting belt-driven linear actuator.

[0036] Figure 6 yes Figure 1 A side view of some selected components of a belt-driven linear actuator, showing the belt topology.

[0037] Figure 7A It is a perspective view of an operating piston with alignment rollers.

[0038] Figure 7B It is a partial cross-sectional view of the operating piston with alignment rollers.

[0039] Figure 8A This is a top view of an example of a pair of misaligned pulleys engaged with a belt.

[0040] Figure 8B This is a perspective view of an example of a pair of misaligned pulleys engaging with a belt.

[0041] Figure 9 This is a flowchart illustrating an example process for pneumatically operating a linear actuator.

[0042] The same reference numerals and symbols in the various figures indicate the same elements. Detailed Implementation

[0043] This disclosure describes a self-alignment system that enables a "keyless" or "rounded profile" piston to be sealed while maintaining alignment and / or torque resistance. This allows the air gap within the electromechanical actuator to be pressurized to perform an auxiliary load holding function that is redundant with linear lead screw devices.

[0044] To help those skilled in the art better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification are clearly and comprehensively described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments in this specification, and not all of them. All other embodiments obtained by those skilled in the art based on one or more embodiments of this specification without creative effort should fall within the protection scope of the embodiments in this specification.

[0045] Figure 1 This is a perspective view of a belt-driven linear actuator 100 including pneumatic operation. The shown linear actuator 100 includes a housing 108 with two gas ports 110A and 110B. A drive motor 102 operates a drive mechanism 104 that moves an output shaft 106 linearly. Gas ports 110A and 110B can be used to pressurize various parts inside the linear actuator 100, as described in more detail below.

[0046] During normal operation, the drive motor 102 converts electrical energy into mechanical energy, which is then converted into motion of the output shaft 106 via the drive mechanism 104. However, in the event of an electrical or internal mechanical failure within the linear actuator 100, backup pneumatic operation can be employed. Typically, linear actuators are used to lift or actuate large loads and usually need to resist external forces (e.g., gravity, resistance, etc.). For safety, some implementations may require redundant load holding and backup operation capabilities. Furthermore, it is advantageous for the system to include safety features that prevent uninstructed or accidental movement of the linear actuator 100 should a fault condition be triggered.

[0047] The pneumatic system can pressurize the various internal volumes of the linear actuator 100 and provide pneumatic operation, including motion inhibition, load manipulation, and controlled unloading of the linear actuator 100. Figure 1 In the illustrated embodiment, a lever locking mechanism 112 is installed to provide additional motion restraint capability. It should be noted that although two gas ports 110A and 110B are shown, in some embodiments only a single gas port is required. Generally, this disclosure discusses pneumatic operation on double-acting or push-pull linear actuators. However, in many embodiments, the linear actuator is configured to operate under load in a single direction (e.g., "compression only" or "tension only"). For these single-acting devices, a single gas port may be suitable.

[0048] The lever lock 112 can be a friction device that mechanically prevents movement of the output shaft 106. For example, the lever lock 112 may include a collar and a set of translational washers that cause the collar to press against the output shaft 106, thereby stopping dynamic movement and holding the load in a static state. Lever lock mechanisms are commercially available, including, for example, Nexsafe lever locks, Amlok locks, or SITEMA safety brakes. The lever lock 112 can be electrically, pneumatically, or hydraulically operated and can be configured to automatically stop or prevent output shaft movement in the event of certain faults, such as power outages, pressure losses, or other electrically triggered signals (e.g., loss of continuity of belt reinforcement measured within the belt of a belt-driven linear actuator).

[0049] Figure 2 yes Figure 1 A perspective view of a belt-driven linear actuator 100, with the outer housing removed to show specific internal components. Other structural components have been removed for clarity. For example, only a portion of the belt 212 is shown; its portion within the expansion pulley system 202 has been removed for clarity. The following is combined with… Figure 6 A more complete description of the topology of belt 212 is provided.

[0050] The linear actuator 100 is typically operated using a belt 212. The belt 212 may consist of two or more steel wire ropes running in a parallel arrangement and covered with polyurethane or other sheathing material. This material arrangement can create a high-strength and highly durable belt capable of withstanding repeated bending and tension stresses when running on relatively small-diameter pulleys. In some embodiments, the steel wire ropes within the belt 212 may be pre-tensioned in a non-uniform manner to increase the torsional and misalignment tolerances of the belt 212.

[0051] In the illustrated embodiment, the linear actuator 100 is a double-acting linear actuator, with the belt 212 arranged in an opposing pulley system topology. The drive mechanism 104 is configured to extract the belt from one pulley system and feed it into another. For example, when the drive mechanism 104 rotates in one direction, the belt 212 is extracted from the expanding pulley system 202 and fed into the contracting pulley system 206, causing the operating piston 204 and output shaft 106 to translate to the right, thereby extending the linear actuator 100. Conversely, if the drive mechanism 104 rotates in the other direction, the belt 212 is extracted from the contracting pulley system 206 and fed into the expanding pulley system 202, causing the operating piston 204 and output shaft 106 to translate to the left, thereby contracting the linear actuator 100.

[0052] The operating piston 204 is fixed to the output shaft 106 and provides a structural member for mounting the traveling pulleys from the contraction pulley system 206 and the expansion pulley system 202. The operating piston 204 is coupled to the output shaft 106 and is housed in the housing (e.g., Figure 1 The linear actuator 100 can be translated within the housing 108. One or more seals 208 can seal different volumes inside the linear actuator 100 and enable selective pressurization or pressure differential across the operating piston 204 to provide pneumatic operation.

[0053] A set of alignment rollers 210 are fixed to the operating piston 204 and to the outer housing (e.g., Figure 1 The housing 108) is engaged. The alignment roller 210 will be discussed in more detail below in conjunction with Figure 7. Overall, the alignment roller 210 resists rotational forces and minimizes the amount of rotation of the operating piston 204 and the output shaft 106 as they travel within the linear actuator 100.

[0054] Figure 3 This is a partially sectional side view of a belt-driven linear actuator including pneumatic operation. The operating piston 204 divides the interior of the linear actuator 100 into two volumes: a proximal volume 302 and a distal volume 304.

[0055] During pneumatic operation, to stop movement caused by an expanding load, the distal volume 304 can be pressurized to create a resistance, thereby preventing or reducing the expansion of the linear actuator 100. Similarly, movement caused by a contracting load can be stopped by pressurizing the proximal volume 302. Alternatively, if movement (e.g., expanding movement) is required, the corresponding volume can be pressurized to induce movement. In applications where pneumatic operation is used for emergency holding or standby operation, the linear actuator 100 can be returned to a stationary state by slowly releasing pressure from the pressurized volume. For example, this would allow the load lifted by the linear actuator 100 to be slowly reduced until the linear actuator 100 is fully contracted (or expanded).

[0056] Figure 4 This is a perspective view of a belt-driven linear actuator, showing the belt loop 402. In a double-acting embodiment of the linear actuator 100, the belt transmits power between the proximal and distal volumes, or between an expanding pulley system and a contracting pulley system. In the example shown, the belt 212 passes through a “rigid line” outside the housing 108. This “rigid line” can act as a bypass during normal operation, allowing gas to flow freely between the distal and proximal volumes. One or more pinch valves can be installed in the belt loop 402 to seal the rigid line when pressurization of either the distal or proximal volume is required.

[0057] The pinch valve may include diaphragms, or in some embodiments, multiple diaphragms bend and seal around belt 212 when the pinch valve is engaged. In some embodiments, the pinch valve may allow belt 212 to move through the pinch valve with restriction while maintaining sufficient sealing to ensure that pressure in the pressurized volume is maintained. In some embodiments, the pinch valve includes a flexible tube (e.g., [missing information]) surrounding the belt. Figure 2 When actuated, a piston or ring deforms the tube around the belt 212 to form a seal. In some embodiments, the pinch valve is electrically operated. In some embodiments, the pinch valve is pneumatically operated. For example, if the pinch valve's sensing line detects pressurized gas, the pinch valve can automatically close, thereby pneumatically separating the distal and proximal volumes.

[0058] Figure 5A This is a schematic diagram of a pneumatic system for pneumatically operating a belt-driven linear actuator 100. Figure 5A The proximal volume 302 and distal volume 304 are shown, separated by the operating piston 204.

[0059] During normal operation, the belt loop 402 can act as a balancing line, allowing pressure to be balanced across the operating piston 204. In the illustrated embodiment, the three-way valve 502 also provides a flow path between the proximal volume 302 and the distal volume 304, further balancing the pressure. In some embodiments, no balancing line is provided, and a relatively small pressure differential is generated across the operating piston 204 as it moves throughout its normal range of motion. Even if one or more air balancing passages are open, the pressure in the proximal volume 302 and the distal volume 304 may still fluctuate as the actuator contracts and expands due to volume displacement caused by the retraction of the output shaft 106 into the housing 108.

[0060] The three-way valve 502 may be a ball valve or other valve with multiple positions and is configured to selectively direct air to either the proximal volume 302 or the distal volume 304. In some embodiments, the three-way valve 502 may have four positions, such as a "to distal" position, a "to proximal" position, a "bypass" position, and a "closed" position. In some embodiments, the three-way valve 502 has three or two positions. Generally, the three-way valve 502 can direct high-energy or pressurized gas released by the isolation valve 504 to an appropriate volume to stop motion or counteract the force generated by the operating load of the linear actuator 100. In some embodiments, the three-way valve 502 is electrically actuated, for example, via a motor or solenoid. In some embodiments, a controller is configured to monitor the operating load on the linear actuator 100 and, as needed, control the three-way valve 502 to align the flow path to the volume that will counteract the operating load. In the event of a system failure, isolation valve 504 can be opened, and the gas will be immediately directed to the appropriate volume to provide resistance and stop movement caused by the operating load.

[0061] The isolation valve 504 can be a gate valve, throttle valve, or other suitable valve, used to isolate high-pressure gas until pressurization of the proximal volume 302 or the distal volume 304 is required. In the illustrated example, the storage tank 510 provides storage volume for the high-pressure gas. In some embodiments, a pump is used instead of a storage tank. That is, in some embodiments, the high-pressure gas is generated on demand upon detection of a fault.

[0062] Figure 5B It shows Figure 5A An alternative supply layout for the pneumatic system. Dual isolation valves replace three-way valves, with each isolation valve directing gas to a specific volume. Figure 5A or Figure 5B In this context, the isolation valve 504 can be pneumatically operated or solenoid-operated, etc. For example, the isolation valve 504 can be kept closed by an electrical signal and configured to automatically open by a spring in the event of a power outage.

[0063] Back Figure 5A When a volume needs to be pressurized, pinch valve 508 provides isolation between the proximal volume 403 and the distal volume 304. In some embodiments, pinch valve 508 automatically shuts off when high-pressure gas flows in via sensing line 506. In some embodiments, pinch valve 508 is electrically shut off (e.g., shut off by the same signal that triggers the opening of isolation valve 504). Pinch valve 508 can be, for example, a valve similar to the AKO VMC pinch valve or the Schubert & Salzburg 7069 type. In some embodiments, pinch valve 508 can be belt-sealed or substantially sealed and maintain a differential pressure of 200 to 1000 pounds per square inch.

[0064] A needle valve 512 can be installed along the supply line to controllably reduce the pressure of the proximal volume 302 or the distal volume 304. In some embodiments, the needle valve 512 is manually operated. In some embodiments, the needle valve 512 is electrically operated or configured as a static valve that leaks slowly over time. If a pneumatic stop event occurs within the linear actuator 100, such as belt failure when the load is suspended, the needle valve 512 allows the operator to safely and slowly lower the load to a resting position.

[0065] Figure 5C This is a schematic diagram of a pneumatic system for pneumatically operating a single-acting belt-driven linear actuator 500. The linear actuator 500 differs from the previously illustrated linear actuator 100 in that it is configured to operate under a unidirectional operating load. In the example shown, the linear actuator 500 is a "compression" actuator, or an actuator configured to expand under power and contract under an externally applied compressive load, with the output shaft 106 subjected to compressive loads in both directions. This configuration is simplified because only a single volume (e.g., proximal volume 302) needs to be pressurized. A single flow path, with an isolated isolation valve 504, is sufficient to support pneumatic operation against the operating load. Since the single-acting linear actuator 500 does not have a belt circuit, a pinch valve 508 is not required.

[0066] Figure 6 This is a side view of some selected components of a belt-driven linear actuator, showing the belt topology. The belt 212 enters from a first anchor 604 into a retraction pulley system 206, which includes multiple stationary pulleys and multiple traveling pulleys, operable to retract the linear actuator 100. The belt 212 then enters a drive system 602, which moves the belt 212 within the linear actuator 100. The belt then enters an expansion pulley system 202 (via...) Figure 4 The belt loop 402 shown passes through the expansion pulley system 202 and terminates at the anchoring part 606. It should be noted that in embodiments without opposing pulley systems, there may be a winding mechanism configured to wind up additional belt when the belt is removed from the operating pulley system (retracting pulley system 206 or expansion pulley system 202).

[0067] To provide an effective seal between the contraction pulley system 206 and the expansion pulley system 202, the dynamically operated seal 208 preferably has a circular or annular form. That is, the operating structure and housing in which the belt system operates can be cylindrical with a smooth internal shape. However, if the angular alignment between the actuator frame and the output rod is not controlled, the output shaft (e.g., Figure 1The output shaft 106 and therefore the traveling pulleys of the contraction pulley system 206 and expansion pulley system 202 may be subjected to torsional or misalignment forces during operation. If the output shaft rotates or twists significantly, misalignment of the internal pulley systems (202 and 206) will lead to rapid belt deterioration and premature failure of the linear actuator 100. Therefore, a system is needed that can maintain pulley alignment within 0.15 degrees and resist externally applied torsional torques.

[0068] Conventional anti-rotation systems use keyways and lugs, or slot and track systems. This disclosure describes an anti-rotation and self-aligning system that does not require keyways or lugs, thus enabling the use of circular or cylindrical seals, such as seal 208. Furthermore, the disclosed system requires no external supports or structures, thus not altering the overall footprint of the linear actuator 100. A set of alignment rollers 210 is provided, which are radially preloaded to engage with the inner surface of the cylindrical outer housing (e.g., ...). Figure 1 The housing 108 engages with the alignment rollers. The alignment rollers resist the rotational movement of the traveling components (e.g., output shaft 106 and operating piston 204) about the drive axis 608.

[0069] Alignment rollers 210 may be formed of polyurethane, metal, metal alloy, or other materials, and their axes of rotation are perpendicularly aligned with the drive shaft 608. Generally, the function of alignment rollers 210 is to prevent large-scale torsion or rotation about the drive shaft 608 that may be caused by external disturbances, but when subjected to a torque of constant direction and magnitude, and over a relatively large linear stroke, alignment rollers 210 allow slight rotation. For example, when subjected to a continuous torque caused by a misaligned belt 212, alignment rollers 210 may allow the output shaft 106 to rotate 0.1 to 1 degree per meter of stroke. This relatively small slippage allows the system to self-align during operation because the force exerted by belt 212 on the inner pulleys of the pulley system (202 and / or 206) generates a corrective torque tending towards a position with zero run-off angle (or true running). This self-alignment will be discussed in detail below. Figure 8A and Figure 8B Further detailed discussion is needed.

[0070] The linear actuator 100 shown in the diagram is a double-acting linear actuator, but as mentioned above... Figure 5C Other configurations discussed are also possible. For example, an actuator with a retraction pulley system 206 that re-expands under operating load but without an expansion pulley system 202 can be a "pull-only" (tension load) configuration. In another example, the actuator can have an expansion pulley system 202 without a retraction pulley system 206 and can be a "push-only" (compression load) actuator. Both examples above will still include alignment rollers 210 to achieve self-alignment characteristics and resist misalignment disturbances.

[0071] Figure 7A This is a perspective view of the operating piston 204 with alignment rollers 210. In the example shown, five alignment rollers 210 are used. However, fewer or more alignment rollers can also be used. For example, a system with three alignment rollers 210 arranged in a triangular pattern can be implemented. The alignment rollers are cantilevered to the structure of the operating piston 204, which allows the tension spring 704 to preload each alignment roller 210 against the outer housing.

[0072] The radial preload alignment roller 210 ensures that a tangential frictional force perpendicular to the radial preload is generated between the alignment roller 210 and the housing, which resists the rotation of the output shaft 106, the operating piston 204, and any grooved wheels attached to the output shaft 106 and / or the operating piston 204.

[0073] The tension springs 704 can be pre-compressed using the positioning screws 702 to adjust the magnitude of the force they apply to each alignment roller 210, thereby achieving the target preload of the alignment rollers 210.

[0074] In general, this construction prevents rapid deviations from true operating alignment by resisting rotational forces or misalignment torques, which may be internal or external to the linear actuator. However, a small amount of rotation will naturally be allowed over the extended stroke, enabling the belt-driven linear actuator to achieve self-alignment characteristics. Specifically, the belt-driven linear actuator will naturally self-align because misaligned pulleys will cause the belt (e.g., Figure 2 Apply alignment force to the belt 212, as described below. Figure 8A and Figure 8B As shown.

[0075] Figure 7B It is a partial cross-sectional view of the operating piston with alignment rollers. Figure 7B The preload force 706 generated by the tension spring 704 is shown. Each alignment roller 210 may have a preload force 706, which ensures that a frictional force 708 can be generated to counteract the torque or torsional force applied to the output shaft 106.

[0076] Figure 8A This is a top view of an example of a pair of misaligned pulleys (802 and 804) engaged with belt 810. The misalignment of pulley 804 relative to pulley 802 causes an increase in sidewall pressure from belt 810 on both pulleys. This results in sidewall forces 806A and 806B.

[0077] Figure 8BThis is a perspective view of an example of a pair of misaligned Geneva pulleys engaged with belt 810. The misalignment results in sidewall forces 806A to 806D, which produce alignment torque 808A applied by belt 810 to Geneva pulley 802 and alignment torque 808B applied by belt 810 to Geneva pulley 804. If either Geneva pulley can rotate freely about axis 812 relative to its opposite Geneva pulley, then alignment will be achieved due to the sidewall forces.

[0078] Back Figure 2 A similar effect applies. If the output shaft 106 twists, the traveling pulleys in the contraction pulley system 206 and the expansion pulley system 202 will misalign with their respective fixed pulleys. This misalignment will cause increased sidewall forces and alignment torque throughout the linear actuator 100, and will cause the output shaft 106 to tend to self-align towards a position with zero deviation angle (or true operation) as it operates, with the alignment roller 210 gradually sliding to allow for corrective action during movement.

[0079] Figure 9 This is a flowchart illustrating an example process 900 for pneumatically operating a linear actuator. It should be understood that process 900 can be performed by any suitable system, environment, software, and hardware, or a suitable combination of such systems, environments, software, and hardware. In some instances, process 900 can be performed by… Figure 1 The process 900 may be performed by the system or portions thereof shown in Figure 7, as well as other components or functions described in other parts of this description. In other instances, process 900 may be performed by multiple connected components or systems. The operations shown may be performed using any suitable system(s), architecture(s), or application(s). Furthermore, it should be noted that not every element of process 900 is suitable for every configuration. For example, a single-acting linear actuator may not require an actuation pinch valve as described below.

[0080] At process 902, the operating load of the linear actuator is monitored. The operating load can be monitored by a controller and one or more sensors. In some embodiments, the operating load is sensed based on the motor driver that drives the linear actuator. For example, motor current, torque, and direction can be used to determine the magnitude of the operating load the linear actuator is experiencing. In another embodiment, one or more sensors measuring belt tension within the linear actuator can be used to identify the operating load. In some embodiments, external sensors separate from the linear actuator (e.g., cameras, weight sensors, etc.) can be used to determine the operating load. Overall, the load on the linear actuator is monitored to determine its magnitude and orientation.

[0081] At process 904, if the operating load causes the linear actuator to contract, process 900 proceeds to process 908. If the operating load causes the linear actuator to expand, process 900 proceeds to process 906. It should be noted that in some configurations where the linear actuator is designed to operate under unidirectional loads, processes 902 and 904 can be combined, and only the magnitude of the operating load needs to be determined. In these configurations, gas alignment and volume selection are not necessary because only one volume may need to be pressurized.

[0082] At process 906, when the operating load causes the linear actuator to expand, gas is aligned to the distal volume within the linear actuator. Gas alignment can be the alignment of flow paths, such as aligning a three-way valve to direct gas from the high-pressure reservoir to the distal volume. Alternatively, gas alignment can indicate "ready" or electrically prepare certain isolation valves to be opened. In any case, the system is configured to prepare for pressurization of the distal volume.

[0083] At process 908, when the operating load causes the linear actuator to contract, gas is aligned to the proximal volume within the linear actuator. Gas alignment can be the alignment of flow paths, such as aligning a three-way valve to direct gas from the high-pressure reservoir to the distal volume. Alternatively, gas alignment can indicate "ready" or electrically prepare certain isolation valves to be opened. In any case, the system is configured to prepare for pressurization of the distal volume.

[0084] At process 910, the system monitors for a malfunction in the linear actuator. Malfunctions may include belt failure, uncommanded movement, belt slippage / overload, motor failure, or other malfunctions indicating a loss of control of the linear actuator. If no malfunction is detected, process 900 returns to process 902 and continues monitoring for operating load and malfunctions. If a malfunction is detected, process 900 proceeds to process 912.

[0085] Optionally, at process 912, a lever locking device is engaged. The lever locking device may be pneumatically, hydraulically, or electrically actuated and is configured to prevent movement of the linear actuator when switching to pneumatic operation. The lever locking device may remain engaged until the appropriate volume is sufficiently pressurized, after which the lever locking device may disengage to allow movement of the linear actuator (e.g., relaxation or lowering).

[0086] At process 914, in some configurations, one or more pinch valves are actuated. The pinch valves form a seal around the belt and separate different volumes (e.g., Figure 3 The distal volume 304 and the proximal volume 302 are isolated from each other. In some embodiments, the pinch valve (one or more) is simultaneously actuated with the volume pressurization. In configurations that include only a single volume or no belt segment requiring sealing, the pinch valve may not be necessary.

[0087] At process 916, the counteracting volume is pressurized. The counteracting volume refers to the volume that counteracts the operating load. In some embodiments, pressurization is achieved by opening an isolation valve between the high-pressure tank and the volume. In some embodiments, pressurization is achieved by rapidly supplying gas to the counteracting volume by starting a compressor or initiating a chemical reaction. In some embodiments, the pressure in the counteracting volume is regulated or controlled and designed to match the operating load. It should be noted that matching the operating load does not necessarily mean that the force generated by the internal pressure is equal to the operating load. Rather, matching can mean that the force difference between the operating load and the pressurized volume is less than a predetermined value (e.g., 1000 kg, 100 kg, or 20 kg, etc.). In some embodiments, matching the internal pressure means that the pressure difference across the operating piston is sufficient to limit the translational speed of the linear actuator to a safe speed (e.g., 5 m / s, 1 m / s, or lower).

[0088] At process 918, after pressurization of the counteracting volume or once pressurization is initiated, the pressure in the counteracting volume is regulated to return the linear actuator to a safe state. For example, the pressure may initially be rapidly increased to match the operating load, thereby stopping motion. The pressure may then be slowly released, for example, using one or more needle valves (e.g., needle valve 512 in Figure 5) to allow the linear actuator to return to a relaxed state in a slow and controlled manner. In some embodiments, a throttle valve may be used to regulate or electronically control the pressure in the counteracting volume to provide backup operation for the linear actuator.

[0089] The foregoing description is provided in the context of one or more specific embodiments. Various modifications, alterations, and variations can be made to the disclosed embodiments without departing from the scope of this disclosure. Therefore, this disclosure is not limited to the described or illustrated embodiments, but should be given the widest scope consistent with the principles and features disclosed herein.

Claims

1. An alignment system for a belt-driven linear actuator, comprising: An actuator frame, the actuator frame including an inner surface; A traveling assembly, the traveling assembly including an operating piston and an output shaft, and configured to translate along a main axis defined by the centerline of the output shaft; A roller, rotatably coupled to the traveling assembly and configured to mechanically engage with the inner surface of the actuator frame, the roller having an axis of rotation perpendicular to the main axis; A first flange grooved wheel is connected to the output shaft; The second flange grooved wheel is connected to the actuator frame; as well as A belt that extends between and around a first pulley and a second pulley.

2. The system according to claim 1, characterized in that, The roller engages with the inner surface via a spring, wherein the spring is preloaded by a positioning screw.

3. The system according to claim 1 or 2, characterized in that, The first flange grooved wheel and the second flange grooved wheel operate as a pulley system, which is configured to allow the output shaft to translate along the axis.

4. The system according to any one of claims 1 to 3, characterized in that, The roller has a curved surface, which is shaped to maximize the contact area between the roller and the inner surface.

5. The system according to any one of claims 1 to 4, characterized in that, The rollers allow the output shaft to rotate about the main axis, with a rotation range between 0.1 and 1 degree per meter of travel.

6. The system according to any one of claims 1 to 5, characterized in that, The roller is one of a plurality of rollers, wherein the plurality of rollers form an annular arrangement that at least partially surrounds the output shaft.

7. A method of operating a belt-driven linear actuator, comprising: The travel assembly of the belt-driven linear actuator is translated; as well as While translating the traveling assembly, the traveling assembly is allowed to rotate about the main axis to correct the alignment of the belt between the first pulley and the second pulley.

8. The method according to claim 7, characterized in that, include: When the traveling component is not translating, it prevents rotation about the main axis.

9. The method according to claim 8, characterized in that, Preventing rotation about the main axis includes using one or more components fixed to the traveling assembly and mechanically engaging with the inner surface of the actuator frame via one or more preloaded springs to resist rotation in a frictional manner.

10. The method according to any one of claims 7 to 9, characterized in that, The linear actuator includes: Actuator frame, the actuator frame including an inner surface; and The traveling assembly includes an operating piston and an output shaft, and is configured to translate along the main axis, wherein the main axis is defined by the centerline of the output shaft.

11. The method according to any one of claims 7 to 10, characterized in that, The linear actuator includes: Actuator frame, the actuator frame including an inner surface; and A roller, rotatably coupled to the traveling assembly and configured to mechanically engage with the inner surface of the actuator frame, the roller having an axis of rotation perpendicular to the main axis.

12. The method according to any one of claims 7 to 11, characterized in that, The first pulley is a flange pulley and is coupled to the traveling assembly, wherein the second pulley is a flange pulley and is coupled to the actuator frame of the linear actuator, and wherein the traveling assembly rotates about the main axis in response to the sidewall forces generated between the first pulley and the second pulley and the belt.

13. The method according to any one of claims 7 to 12, characterized in that, Allowing the travel component to rotate includes allowing the travel component to rotate within a range of 0.1 to 1 degree per meter of travel.

14. The method according to any one of claims 7 to 13, characterized in that, The first and second grooved wheels operate as a pulley system configured to allow the traveling component to translate along the main axis.

15. A system for operating a belt-driven linear actuator, comprising: A pneumatically operated system, the pneumatically operated system comprising: - Proximal volume; - Distal volume; - An operating piston, fixed to the output shaft of the linear actuator, the operating piston separating the distal volume and the proximal volume; and - A valve configured to direct gas to the distal volume or the proximal volume, thereby generating a pressure differential across the operating piston; and An alignment system configured to maintain rotational alignment of the output shaft of the linear actuator, the alignment system comprising: - An actuator frame, the actuator frame including an inner surface; - A roller, rotatably coupled to the travel assembly and configured to mechanically engage with the inner surface of the actuator frame, the roller having an axis of rotation perpendicular to the main axis defined by the centerline of the output shaft; - A first flange grooved wheel, which is connected to the output shaft; - A second flanged grooved wheel, the second flanged grooved wheel being coupled to the actuator frame; and - A flat belt that extends between and around a first pulley and a second pulley.

16. The system according to claim 15, characterized in that, The roller engages with the inner surface via a spring, wherein the spring is preloaded by a positioning screw.

17. The system according to claim 15 or 16, characterized in that, The first flange grooved wheel and the second flange grooved wheel operate as a pulley system, which is configured to allow the operating piston to translate along the main axis.

18. The system according to any one of claims 15 to 17, characterized in that, The roller has a curved surface, which is shaped to maximize the contact area between the roller and the inner surface.

19. The system according to any one of claims 15 to 18, characterized in that, The valve is a three-way valve, capable of selectively directing gas to either the distal volume or the proximal volume, and the system includes: An isolation valve, configured to initiate gas flow when opened; and A controller configured to receive information related to the operating load of the linear actuator and to align the three-way valve to direct gas against the operating load.

20. The system according to claim 19, characterized in that, The controller is configured to adjust the pressure provided by the isolation valve so that the pressure difference across the operating piston matches the operating load.

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