Curvilinear helical actuator

Abstract

The present invention describes a curvilinear helical actuator that converts curvilinear helical motion into rotational motion. The actuator comprises a helical conduit, a helical crosshead piston unit, a sliding crank pin, a crank, and an output shaft. Fluidic pressure drives the piston unit within the helical conduit, generating a curvilinear motion, which is then transferred as rotational motion to the crank via the crank pin that is connected to the crank using a sliding joint. The actuator features configurations for dual opposing pistons, single acting without spring, and single acting with spring, enhancing control for applications such as prosthetic limbs and robotics. Additionally, it supports extended motion ranges exceeding 360 degrees. Its compact design and efficient motion conversion make it suitable for medical devices, aerospace, automotive, and manufacturing industries, providing precise and reliable motion control.

Description

Curvilinear Helical Actuator Technical Field

[0001] The present invention is broadly directed to fluidic actuators, in particular to such actuators which convert curvilinear helical motion to rotational to pivot a first structure relative to a second structure. Background Art

[0002] The term "linear actuator" is commonly used in the field of actuators to refer to an actuator that produces straight-line motion (rectilinear translation). In this application, the term "linear" refers to rectilinear translation, even though curvilinear translation also falls under the category of linear translation in terms of kinematics.

[0003] Many mechanical systems require rotational motion. Rotary actuators are often used in applications needing precise motion control, such as prosthetic devices, robotic joints, and other mechanical systems. For example, special motor vehicles use rotary actuators for lifting platforms, enabling work at high places and around obstacles like electrical and telephone lines, duct work, and trees during construction, repairs, or maintenance work. In applications such as robotic arms, a rotary pivot range greater than 360° is desirable.

[0004] Various prior art approaches exist to convert linear motion into rotational motion. Some notable mechanisms include: - Rack-and-pinion mechanism (see JP2003049805A or US2024141927A1) - Slotted cam and follower mechanism (see KR101761827B1 or US2014123789A1) - Swashplate (see US20050186085A1 or US20090290996A1)- Three-bar mechanism (see KR20110093176A or KR20100005843A) - Helical-spline and groove (see US9476433B2 or US7267044B1) - Helical-crankshaft and axial-piston mechanism (see CA2642613A1) - Ball-and-piston rotary actuator mechanism (see US8683883B2) Some problems associated with these linear actuators include limited range of motion, excessive space requirements, high friction, and a large number of moving parts. These factors tends to increase design complexity, weight, and / or potential points of failure, making these approaches less efficient and reliable.

[0005] Another approach involves fluidic actuators that convert curvilinear translatory motion into rotary motion. Examples include: - Arcuate-piston-and-cylinder (see US10352169B2 or US9709078B2) - Toroidal actuator (see US2009031718A1 or ES2580329A1) However, a significant disadvantage of these actuators is that their pivot range does not exceed 360° due to the design.

[0006] Therefore, there is a need for fluidic actuators that provide a compact form factor, reducing the space required and potentially lowering the costs associated with their manufacture and use. Additionally, these actuators should offer a pivot range exceeding 360° and provide consistent and potentially high output torque. Summary of Invention

[0007] The present invention introduces a curvilinear helical actuator designed to convert curvilinear helical motion into rotational and vice versa. This actuator mechanism is compact, reliable, and suitable for various applications requiring precise control over rotational movement.

[0008] The curvilinear helical actuator comprises several key components working in harmony to achieve its intended function. The primary elements include a first housing unit with a helical conduit, a helical crosshead piston unit, a sliding crank pin, and an output crankshaft. Each component plays a crucial role in ensuring the actuator operates smoothly and efficiently.

[0009] At the heart of the actuator is the helical crosshead piston unit, which consists of a helical piston head, a helical piston rod, and a helical crosshead. The piston unit is designed to traverse within a helical cylinder, which is essentially a hollow helical coil or a housing with a helical conduit. One end of the helical cylinder is connected to a hydraulic or pneumatic power source, which provides the necessary fluidic pressure to actuate the piston. The other end of the cylinder remains open to facilitate the piston’s movement.

[0010] As fluidic pressure is applied to the piston head, the helical crosshead piston unit moves in a curvilinear translatory motion along the helical path of the helical cylinder. This motion is transferred to the sliding crank pin, which is connected to the helical crosshead. The sliding crank pin is a cylindrical rod with one end fixed to the helical crosshead and the other end passing through a cylindrical hole on the output crankshaft via a prismatic (sliding) joint. These sliding joints play a pivotal role in converting the curvilinear motion of the helical crosshead into rotational motion.

[0011] The output crankshaft, which extends through ball bearings or roller bearings, supports the sliding crank pin and facilitates the transfer of motion. These bearings allow the output crankshaft to spin with minimal friction, ensuring smooth operation. The output shaft, fixed to the crank on one end and connected to the crank pin on the other, facilitates this transfer of motion.

[0012] The output crankshaft’s longitudinal axis of rotation aligns with the central axis of the helical cylinder, ensuring the desired rotational motion is achieved whilerestricting other degrees of freedom. Depending on the design, the crank can either be a separate component or integrated with the output shaft.

[0013] This design reduces the number of moving parts, enhancing the reliability and efficiency of the actuator while minimizing the risk of mechanical failure.

[0014] The innovative design of the actuator, with its helical crosshead piston unit and cylinder, allows for a significant range of motion exceeding 360°. This extensive rotational capability makes the actuator ideal for applications such as robotic joints, prosthetic devices, and other mechanical systems where space, weight, and cost constraints are significant factors. In an alternate embodiment of the present invention, the curvilinear helical actuator may be designed to convert curvilinear (helical) motion into roto-linear, and / or linear motion, and vice versa if needed.

[0015] The actuator’s ability to convert curvilinear helical motion into rotational motion is further enhanced by the careful design of its components. The helical crosshead piston unit and cylinder have matching helical geometries, ensuring seamless motion. The sliding crank pin’s connection to the helical crosshead and output crankshaft allows for precise motion transfer, resulting in high output torque and efficient performance.

[0016] The described embodiments of the fluidic curvilinear actuator demonstrate its capabilities and advantages. However, the invention is not limited to these embodiments. Various modifications and variations can be made without departing from the spirit and scope of the invention, as defined in the appended claims. Brief Description of Drawings The following detailed description will be better understood when read in conjunction with the appended drawings, in which there are shown example embodiments for the purposes of illustration. It should be understood that specific structural and functionaldetails disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Description of Figures Fig.1a and 1b: Perspective views showing the motion of the helical piston through the actuator. Fig.1c: Exploded view detailing the individual components of the actuator. Fig.1d: Isometric shaded view of the 3D model of the actuator. Fig.1e: Top view illustrating the layout of the actuator components. Fig.1f: Front view providing a straight-on perspective of the actuator. Fig.1g: Sectioned view along the line AA, showing the internal configuration of the actuator components. Fig.2a: Sectioned view along line BB, displaying the internal configuration of the actuator components, including the enhanced helical crosshead guide sleeves. Fig.2b: Top view illustrating the layout of the actuator components. Fig.2c and 2d: Comparison views detailing the individual components of the first example and the second example.Fig.3a: Top view illustrating the layout of the entire assembly of the curvilinear helical actuator. Fig.3b: Side view showing the profile of the actuator assembly. Fig.3c: Front view providing a straight-on perspective of the actuator. Fig.3d: Exploded view detailing the individual components of the actuator, including the modifications for the dual opposing actuators. Fig.3e: Isometric view providing a 3D representation of the total assembly, showing the overall structure and design. Description of Embodiments In the preferred embodiments of the invention shown in the drawings Fig.1a to 1g, a curvilinear helical actuator consists of a single acting helical crosshead piston with no spring return nor spring extension. It is understood, however, that the principle of the actuator may operate with a single acting helical crosshead piston with spring return nor spring. Aside from the preferred embodiment or embodiments disclosed below, this invention is capable of other embodiments and of being practiced or being carried out in various ways. Thus, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. If only one embodiment is described herein, the claims hereof are not to be limited to that embodiment. Moreover, the claims hereof are not to be read restrictively unless there is clear and convincing evidence manifesting a certain exclusion, restriction, or disclaimer.

[0018] The embodiment depicted in the accompanying figures illustrates the operation and components of the fluidic curvilinear helical actuator. The actuator comprises several key components, including a helical piston head (201a), a helical cylinder (101a), a sliding crank pin (3), a crank (401), and an output shaft (411).

[0019] The first housing unit (1), comprising the first helical cylinder (101a) or the first housing with a helical conduit (111a), is designed to guide the motion of the helical piston head (201a). The helical cylinder (101a) is connected to a hydraulic or pneumatic power source at one end, known as the first feed conduit (AFa), which directs pressurized fluid into the helical conduit. The other end of the cylinder remains open, allowing the piston head (201a) to traverse its entire length.

[0020] The helical piston head (201a), part of the helical crosshead piston unit (2), features a helical piston rod (211a) and a helical crosshead (221a). The piston unit (2) is designed to move within the helical cylinder (101a). When fluidic pressure is applied to the piston head (201a), the piston unit (2) moves along the helical path defined by the helical cylinder (101a). This movement is curvilinear and translatory due to the helical geometry of the cylinder (101a).

[0021] The sliding crank pin (3) is attached to the helical crosshead (221a) at one end. The other end of the sliding crank pin (3) passes through a cylindrical hole on the crank (401) via a prismatic (sliding) joint. As the helical piston head (201a) moves through the helical cylinder (101a), the sliding crank pin (3) translates this motion into a combination of rotational and linear movements. The crank (401) revolves around the central axis while also moving along the helical path of the piston head (201a).

[0022] The output crankshaft (4) consists of the crank (401) and the output shaft (411). The crank (401) supports the sliding crank pin (3) and facilitates the transfer of motion to the output shaft (411). The output shaft (411) is supported by ball bearings or roller bearings, which minimize friction and allow for smooth rotation. Thisarrangement ensures that the motion generated by the helical piston head (201a) and crank (401) is efficiently transferred to the output shaft (411).

[0023] The output shaft (411) is fixedly coupled to the crank (401) and serves as the point from which the rotational output is harnessed. The output shaft’s (411) longitudinal axis of rotation aligns with the central axis of the helical cylinder (101a), ensuring that the rotational motion is consistent and precise. The output shaft (411) can either be a separate component or integrated with the crank (401).

[0024] The diagram highlights the relationship between the components. The helical piston head (201a) moves along the helical path within the helical cylinder (101a), driven by the fluidic pressure. The sliding crank pin (3) translates the curvilinear translatory motion of the piston head (201a) into rotational motion, which is then transferred through the crank (401) to the output shaft (411).

[0025] This embodiment showcases the efficiency of the fluidic curvilinear helical actuator in converting curvilinear translatory motion into rotational motion. The design leverages the helical geometry of the piston head (201a) and cylinder (101a), the motion translation capabilities of the sliding crank pin (3), and the smooth rotation provided by the crank (401) and bearings to achieve a compact and reliable actuator suitable for various applications requiring precise rotational control. In the preferred embodiments of the invention shown in the drawings Fig.2a 2b, and 2d, a curvilinear helical actuator is depicted with an extended range of motion, capable of multiple turns. This actuator features modifications to the helical crosshead guide sleeves to accommodate the increased range. It is understood, however, that the principle of the actuator may be applied in various forms, and the actual design may differ from the illustrations. The following detailed description will be better understood when read in conjunction with the appended drawings, which illustrate example embodiments for the purposes of explanation. Specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative foundation for instructingthose skilled in the art to employ the present invention in various appropriately detailed structures.

[0026] The second embodiment of the fluidic curvilinear helical actuator, depicted in Fig.2a to 2d, incorporates several design modifications to increase the actuator's range of motion. This version is capable of multiple turns, enhancing its applicability for various high-precision rotational tasks.

[0027] The primary change in this embodiment is the increased number of turns the actuator can perform, providing a pivot range greater than 360 degrees. This extended range of motion necessitated modifications to the helical crosshead guide sleeves (222a) to ensure that there are no obstructions for the sliding crank pin (3) as it follows the helical path.

[0028] The enhanced helical crosshead guide sleeves (222a) have been redesigned to accommodate the extended motion path of the sliding crank pin (3). This ensures smooth operation and prevents any potential interference or blockage that could hinder the movement of the crank pin as it navigates the helical conduit (112a).

[0029] The working principles of this embodiment remain consistent with the first embodiment. The helical piston head (202a), driven by fluidic pressure, moves along the helical path within the helical cylinder (102a). The sliding crank pin (3) translates this curvilinear translatory motion into rotational motion, which is then transferred through the longer crank (402) to the output shaft (412). The overall mechanism ensures efficient and precise conversion of curvilinear motion to rotational motion, suitable for high-precision applications.

[0030] The final embodiment depicted in the accompanying figures illustrates the operation and components of the dual opposing fluidic curvilinear helical actuator. This actuator comprises several key components working in unison to achieve precise control over rotational and translational movements. The primary elementsinclude the first structure (10) and the second structure (11), which are crucial for mounting the actuator to the upper arm and forearm parts of a prosthetic limb, respectively.

[0031] The assembly includes two helical piston heads (203a, 203b) housed within their respective helical cylinders (103a, 103b). Each helical piston head (203a, 203b) features a helical piston rod (213a, 213b) and a helical crosshead (223a, 223b), designed to move within the helical cylinders (103a, 103b). The cylinders are connected to a hydraulic or pneumatic power source via feed conduits, which direct pressurized fluid into the helical conduits.

[0032] As fluidic pressure is applied, the helical piston heads (203a, 203b) move along their respective helical paths, generating curvilinear translatory motion. This motion is transferred to sliding crank pins (403a, 403b), which are attached to the helical crossheads (223a, 223b) at one end. The other ends of the sliding crank pins (403a, 403b) pass through cylindrical holes on the cranks (401, 402) via prismatic joints, converting the curvilinear motion into a combination of rotational and linear movements.

[0033] The dual output crankshafts consist of the cranks (401, 402) and the output shafts (411, 412). The cranks (401, 402) support the sliding crank pins (403a, 403b) and facilitate the transfer of motion to the output shafts (411, 412). The output shafts (411, 412) are supported by ball bearings or roller bearings, minimizing friction and ensuring smooth rotation. This arrangement ensures that the motion generated by the helical piston heads (203a, 203b) and cranks (401, 402) is efficiently transferred to the output shafts (411, 412).

[0034] The first structure (10) is attached to the housing, serving as the mounting point for the upper arm part of a prosthetic limb. The second structure (11) connects to the forearm part, enabling precise and controlled movement of the prosthetic limb.The dual actuator setup allows for enhanced control, flexibility, and range of motion, making it particularly suitable for applications requiring fine motor skills and high precision.

[0035] The exploded view (Fig.3d) highlights the relationship between the components, showing the detailed assembly of the actuator. The helical piston heads (203a, 203b) move along the helical paths within the helical cylinders (103a, 103b), driven by fluidic pressure. The sliding crank pins (403a, 403b) translate the curvilinear translatory motion into rotational motion, which is then transferred through the cranks (401, 402) to the output shafts (411, 412).

[0036] This embodiment demonstrates the efficiency of the dual opposing fluidic curvilinear helical actuator in converting curvilinear translatory motion into rotational motion. The design leverages the helical geometry of the piston heads (203a, 203b) and cylinders (103a, 103b), the motion translation capabilities of the sliding crank pins (403a, 403b), and the smooth rotation provided by the cranks (401, 402) and bearings to achieve a compact and reliable actuator suitable for various applications requiring precise rotational control. Industrial Applicability The curvilinear helical actuator described in this patent application, including its various embodiments, has significant industrial applicability across multiple sectors requiring precise and controlled motion. Below are key areas where this actuator can be effectively utilized: 1. Prosthetic Limbs: o The dual opposing actuator configuration, as well as the single and extended range variants, are ideal for prosthetic limbs. They provide enhanced control and flexibility, allowing for fine motor skills and high-precision tasks. This greatly improves the functionality and usability of prosthetic devices, enabling more natural and responsive movements. Systems: In robotics, the actuator can be applied in articulated robots and robotic arms where precise rotational and translational motion control is crucial. The compact design and high range of motion make it suitable for complex tasks in automation, assembly, and material handling.l Devices: Medical devices that require precise movement, such as surgical robots and diagnostic equipment, can benefit from the reliability and accuracy of the curvilinear helical actuator. Its smooth and controlled motion is essential for delicate and precise medical procedures.ace: In aerospace applications, the compact design and efficient motion conversion of the actuator make it suitable for use in control surfaces, satellite deployment mechanisms, and other aerospace components requiring precise motion control. The extended range of motion ensures greater flexibility in aerospace design. tive Industry: The automotive industry can utilize this actuator in applications such as active suspension systems, steering mechanisms, and other components requiring precise motion control. Its robust design and reliability ensure long-term performance in demanding automotive environments. cturing and Automation: The actuator’s precise control capabilities make it ideal for manufacturing and automation processes that require accurate positioning and movement of components. It can be used in CNC machines, pick-and-place robots, and other automated systems to enhance productivity and precision. er Electronics: In consumer electronics, the actuator can be used in devices that require precise control of motion, such as camera gimbals, drones, andother devices with movable parts. Its compact size and precise motion control enhance the functionality and user experience of these devices. 8. Industrial Machinery: o Industrial machinery requiring precise control of moving parts, such as conveyor systems, packaging machines, and assembly lines, can benefit from the curvilinear helical actuator. Its ability to convert curvilinear translatory motion into rotational motion ensures efficient and accurate operation in various industrial applications. In summary, the curvilinear helical actuator, in its various embodiments, is a versatile and highly applicable technology that can be used across multiple industries requiring precise and controlled motion. Its innovative design, combining compactness with high precision and extended range of motion, makes it a valuable component for enhancing the performance and functionality of various mechanical and electromechanical systems. Reference Signs List Here is the reference signs list for the various components of the curvilinear helical actuator described in the different embodiments: 1. Housing unit with helical conduit • 101a, 102a – Housing block (simplified helical cylinder) • 103a, 103b – Reinforced housing block (prototype implementation) • 111a, 112a, 113a, 113b – Helical conduit • 121a, 122a, 123a, 123b – Helical crosshead guide sleeve • 141a – Optional end-stop • 131a, 132a, 133a, 133b – Mounting structure (optional internal support) • AFa – Input feed conduit 2. Helical Crosshead Piston Unit • 201a, 202a, 203a, 203b – Helical piston head• 211a, 212a, 213a, 213b – Helical piston rod • 221a, 222a, 223a, 223b – Helical crosshead 3. Sliding crank pin • 301, 302, – Sliding crank pin (first and second embodiment) • 303 –Sliding crank pin (third embodiment / prototype) 4. Output Crankshaft Unit • 400 – Output crankshaft unit • 401, 402 – Crank (first and second embodiment) • 403 – Shared crank (prototype / third embodiment) • 403a, 403b – Crank couplers (prototype fastening elements) • 411, 412 – Output shaft (first and second embodiment) • 413 – Central output shaft (third embodiment / prototype) Mounting Interfaces (Prototype) • 10 – First structure (mounting interface for upper arm section) • 11 – Second structure (mounting interface for forearm section)

Claims

Claims 1. A curvilinear helical actuator comprising: - a first housing unit with a helical conduit; - a helical crosshead piston unit, including a helical piston head, a helical piston rod, and a helical crosshead, the piston unit designed to move within the helical conduit of the first housing unit; - a sliding crank pin attached to the helical crosshead; - a crank with a prismatic joint that receives the sliding crank pin; and - an output shaft coupled to the crank, where the output shaft is supported by bearings to allow rotation, the actuator configured to convert curvilinear translatory motion of the helical crosshead piston unit into rotational motion of the output shaft.

2. The actuator of claim 1, wherein the helical conduit is connected to a hydraulic or pneumatic power source at one end, which provides fluidic pressure to actuate the helical crosshead piston unit.

3. The actuator of claim 1, wherein the other end of the helical conduit remains open to facilitate the movement of the helical crosshead piston unit.

4. The actuator of claim 1, wherein the output shaft’s longitudinal axis of rotation aligns with the central axis of the helical conduit.

5. The actuator is configured as a single-acting unit or as a dual mirrored actuator system enabling bidirectional motion.

6. The actuator of claim 1, wherein the actuator includes a spring for spring return.

7. The actuator of claim 1, further comprising a dual mirrored configuration, in which two helical crosshead piston units are housed within respective helical conduits, each capable of independent actuation in opposite directions.

8. The actuator of claim 7, wherein the sliding crank pins translate the curvilinear translatory motion of the helical crosshead piston units into rotational motion, which is then transferred through a shared crank to a central output shaft..

9. The actuator of claim 1, wherein the helical conduit, the helical crosshead, and the helical crosshead guide sleeve are structurally modified to accommodate an extended range of motion, providing a pivot range greater than 360 degrees..

10. The actuator of claim 9, wherein the enhanced helical crosshead guide sleeve are designed to ensure smooth operation and prevent mechanical obstructions for the sliding crank pin during extended travel along the helical path.

11. The actuator of claim 1, wherein the first structure is attached to the housing, serving as a mounting point for various applications, enabling precise and controlled movement of the connected structure.

12. A method of converting curvilinear translatory motion into rotational motion using a curvilinear helical actuator, the method comprising: - providing a helical conduit within a first housing unit; - actuating a helical crosshead piston unit within the helical conduit using fluidic pressure; - attaching a sliding crank pin to a helical crosshead of the piston unit; - translating the curvilinear translatory motion of the helical crosshead piston unit into a combination of rotational and linear movements using the sliding crank pin and a crank; and - transferring the rotational motion to an output shaft supported by bearings to allow rotation.

13. The method of claim 12, wherein the helical crosshead guide sleeves are enhanced to accommodate multiple turns of the helical crosshead piston unit, providing a pivot range greater than 360 degrees.

14. The method of claim 12, wherein the actuator comprises dual opposing helical crosshead piston units housed within respective helical conduits, each piston unit moving in opposite directions, and the method includes transferring the rotational motion through dual output shafts.

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