Electric actuators for marine steering systems

Abstract

A ship steering system includes a ship propulsion unit, a steering tiller having a first end and a second end opposite the first end and pivotably coupled to the ship propulsion unit in close proximity to the second end, and an electric actuator. The electric actuator includes an output shaft, a motor that drives the rotation of the output shaft about an axis, and a driven assembly pivotably coupled to the steering tiller in close proximity to the first end and operably coupled to the output shaft, such that the rotation of the output shaft by the motor drives the axial movement of the driven assembly relative to the output shaft and motor in order to steer the ship propulsion unit via the steering tiller.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims the benefit of priority under 35 U.S.C. § 119 to U.S. Patent Application No. 18 / 616,439, filed Mar. 26, 2024, which claims the benefit of U.S. Provisional Patent Application No. 63 / 454,972, filed Mar. 28, 2023, and U.S. Provisional Patent Application No. 63 / 463,083, filed May 1, 2023, the entire contents of which are incorporated herein by reference.

[0002] Technical Field This disclosure generally relates to marine steering systems. More particularly, this disclosure relates to marine steering systems and electric actuators for marine steering systems.

Background Art

[0003] A ship can include a steering system having an electric actuator. Due to the limited space between the engine cowling and the hull of a ship, it is desirable to have an electric actuator for a marine steering system that has a small space occupation area while meeting the requirements of durability and performance.

Summary of the Invention

Means for Solving the Problems

[0004] According to a first aspect of the present disclosure, a ship steering system includes a ship propulsion unit, a steering tiller having a first end and a second end opposite the first end and pivotably coupled to the ship propulsion unit in proximity to the second end, and an electric actuator. The electric actuator includes an output shaft, a motor for driving the rotation of the output shaft about an axis, and a driven assembly, which is pivotably coupled to the steering tiller in proximity to the first end and operably coupled to the output shaft, such that the rotation of the output shaft by the motor drives the axial movement of the driven assembly relative to the output shaft and motor to steer the ship propulsion unit via the steering tiller.

[0005] Embodiments of the first aspect of this disclosure may include any one or a combination of the following features: - The driven assembly includes a housing and a nut tube housed by and fixed to the housing, which receives a central screw fixedly coupled to an output shaft, and which is translatable along the shaft in response to the motor rotating the output shaft. - A ship steering system includes a roller screw assembly comprising a central screw fixedly coupled to an output shaft, a nut tube that receives the central screw internally, and a plurality of rollers radially positioned between the central screw and the nut tube and configured to engage with the central screw and the nut tube. - Multiple rollers are connected to a central screw in a way that prevents translation, such that the axial position of each of the multiple rollers is fixed with respect to the central screw. - The motor is located outside the housing. - The motor is offset axially from the entire driven assembly. - The motor and output shaft are coaxially aligned so that they rotate around the axis. - The motor includes a stator and a rotor, which is configured to rotate relative to the stator about a rotor axis that is radially offset from the axis around which the output shaft rotates. - The motor is drivable and connected to the output shaft via a gear set. - The motor is drivably connected to the output shaft via a belt. - The driven assembly is pivotably coupled to the housing and is operable to pivot relative to the housing about a pivot plate axis which is parallel to the axis around which the output shaft rotates; the steering tiller is pivotably coupled to the driven assembly via a pivot coupling to the pivot plate such that the pivot plate is operable to pivot relative to the housing about the pivot plate axis; the steering tiller includes a pivot plate which is operable to pivot relative to the pivot plate. - The electric actuator further includes a support structure having a support arm that is offset axially from the housing and configured to prevent axial movement of the output shaft, wherein the motor is housed by the support arm such that axial movement of the motor relative to the support arm is prevented. - The electric actuator further includes a mounting shaft configured to facilitate the pivotal movement of the support structure, motor, output shaft, and housing, with respect to a pivot axis that is coupled to the support structure, extends parallel to the axis, and is radially offset from the axis and the pivot plate axis. - Full stroke operation of the electric actuator facilitates the pivotal movement of the support structure, motor, output shaft, and housing around the pivot axis, the pivotal movement of the pivot plate relative to the housing around the pivot plate axis, the pivotal movement of the steering tiller relative to the pivot plate, and the pivotal movement of the steering tiller relative to the ship's propulsion unit. - A ship's propulsion unit is an engine.

[0006] According to a second aspect of the present disclosure, an electric actuator for a ship steering system includes a housing, a first output shaft extending axially outward from the housing in a first axial direction, a first motor located outside the housing and drive-engaged with the first output shaft such that the first motor is operable to drive the rotation of the first output shaft about an axis, and a roller screw assembly located inside the housing and coupled to the first output shaft. The roller screw assembly has a nut tube fixed to the housing and a central screw received by the nut tube. Furthermore, the nut tube is axially translatable in response to the first motor rotating the first output shaft and the central screw about an axis.

[0007] Embodiments of the second aspect of this disclosure may include any one or a combination of the following features: - A second output shaft coupled to a roller screw assembly and extending axially outward from the housing in a second axial direction opposite to the first axial direction, and a second motor located outside the housing and drive-engaged with the second output shaft. A pivot plate that is pivotably coupled to a housing and is operable to pivot relative to the housing about a pivot plate axis which is parallel to an axis in which a first output shaft rotates, wherein a steering tiller of a ship steering system is pivotably coupled to the pivot plate. - The rotation of the first output shaft causes the nut tube to move axially parallel to the first motor.

[0008] According to a third aspect of the present disclosure, a ship steering system includes a ship propulsion unit, a steering tiller having a first end and a second end opposite to the first end and pivotably coupled to the ship propulsion unit in proximity to the second end, and an electric actuator. The electric actuator includes a housing, a pivot plate pivotably coupled to the housing and operable to pivot relative to the housing about a pivot plate axis, the steering tiller pivotably coupled to the pivot plate in proximity to the first end of the steering tiller such that the pivot plate is operable to pivot relative to the housing about a pivot plate axis, and the steering tiller is operable to pivot relative to the pivot plate. The electric actuator also includes a first output shaft extending axially outward from the housing in a first axial direction, and a second output shaft extending axially outward from the housing in a second axial direction opposite to the first axial direction. In addition, the electric actuator includes a first motor, which is located outside the housing and is drive-engaged with the first output shaft so that the first motor can operate to drive the rotation of the first output shaft about an axis; and a second motor, which is located outside the housing and is drive-engaged with the second output shaft so that the second motor can operate to drive the rotation of the second output shaft about an axis. Furthermore, the electric actuator includes a roller screw assembly located inside the housing and coupled to the first and second output shafts. The roller screw assembly has a nut tube fixed to the housing and a central screw received by the nut tube. Furthermore, the nut tube is configured to translate axially along the axis in response to the rotation of the central screw via at least one of the first motor driving the rotation of the first output shaft and the second motor driving the rotation of the second output shaft.

[0009] These and other features, advantages, and purposes of this disclosure will be further understood and recognized by those skilled in the art by referring to the following specification, claims, and accompanying drawings. [Brief explanation of the drawing]

[0010] [Figure 1] This is a top view of a ship steering system including an electric actuator according to an exemplary embodiment of the present disclosure. [Figure 2] This is a cross-sectional view of a portion of an electric actuator for a marine steering system, illustrating a first and second output shafts extending outward from a housing containing a roller screw assembly, according to an exemplary embodiment of the present disclosure. [Figure 3] This is a top view of a ship steering system including an electric actuator having a first motor driven and engaged with a first output shaft via a gear train and a second motor driven and engaged with a second output shaft via a belt, according to an exemplary embodiment of the present disclosure. [Figure 4] This is a top view of a plurality of rollers and a center screw of a roller screw assembly of an electric actuator for a ship steering system, according to an exemplary embodiment of the present disclosure. [Modes for carrying out the invention]

[0011] The elements in the figures are not necessarily to scale; instead, the focus is on illustrating the principles described herein.

[0012] Additional features and advantages of this disclosure will be revealed in the following detailed description and will be apparent to those skilled in the art from that description, or will be recognized by practicing this disclosure as described below, together with the claims and accompanying drawings.

[0013] As used herein, the term "and / or" means, when used in a list of two or more items, that any one of the listed items may be used alone, or any combination of two or more of the listed items may be used. For example, if a composition is described as containing components A, B, and / or C, the composition may contain A alone, B alone, C alone, A and B in combination, A and C in combination, B and C in combination, or A, B, and C in combination.

[0014] In this specification, relational terms such as “first” and “second,” “upper” and “lower” are used solely to distinguish one entity or action from another entity or action, and do not necessarily require or imply any actual relationship or order between such entities or actions.

[0015] For the purposes of this disclosure, the term “coupled” (in all its variations, i.e., in “couple,” “coupling,” “coupled,” etc.) generally means that two components are joined to one another, directly or indirectly (electrically or mechanically). Such a joint may be essentially stationary or essentially movable. Such a joint may be achieved using two components (electrically or mechanically) and / or any additional intermediate members. Such a joint may involve the members being formed integrally with one another as a single unit (i.e., being integrally coupled), or it may refer to the joining of two components. Such a joint may be essentially permanent or essentially removable or detachable, unless otherwise specified.

[0016] As used herein, the terms "the", "a", or "an" mean "at least one" and should not be limited to "only one" unless the contrary is expressly indicated. Thus, for example, reference to "a component" includes embodiments having two or more such components unless the context clearly indicates otherwise.

[0017] As used herein, the term "axial" and derivatives thereof such as "axially" are to be understood to refer to a direction along the axis. Further, the term "radial" and derivatives thereof such as "radially" are to be understood in relation to the aforementioned axis. For example, "radially outboard" refers to being farther away from the axis, and "radially inboard" refers to being closer to the axis. The term "circumferential" and derivatives thereof such as "circumferentially" are to be understood in relation to the aforementioned axis. Further, the term "coaxial" and derivatives thereof such as "coaxially aligned" are to be understood to refer to elements configured to rotate about a common axis. Unless the context clearly dictates otherwise, "axial", "radial", "circumferential", and their respective derivatives are to be understood with reference to the axis about which the output shaft of the marine steering system rotates.

[0018] Referring now to FIGS. 1-4, the marine steering system 10 includes a marine propulsion unit 12. The steering tiller 14 includes a first end 16 and a second end 18 opposite the first end 16. The steering tiller 14 is pivotally coupled to the marine propulsion unit 12 proximate the second end 18 of the steering tiller 14. The marine steering system 10 includes an electric actuator 20. The electric actuator 20 includes an output shaft 22, a motor 24 that drives rotation of the output shaft 22 about an axis 26, and a driven assembly 28. The driven assembly 28 is pivotally coupled to the steering tiller 14 proximate the first end 16 of the steering tiller 14 and is operatively coupled to the output shaft 22. Rotation of the output shaft 22 by the motor 24 drives axial movement of the driven assembly 28 relative to the output shaft 22 and the motor 24 to steer the marine propulsion unit 12 via the steering tiller 14.

[0019] Referring now to FIG. 1, the marine steering system 10 includes a marine propulsion unit 12. The marine propulsion unit 12 is configured to be coupled to a marine vessel (not shown) and to propel the marine vessel within a body of water. The marine propulsion unit 12 can be an engine 30, such as an outboard engine, configured to be mounted proximate the stern of the marine vessel. Various arrangements and types of the marine propulsion unit 12 (e.g., an electric motor) are contemplated. The marine propulsion unit 12 can be configured to pivot and / or swivel relative to the marine vessel to enable steering of the marine vessel as further described herein.

[0020] Referring further to Figure 1, the ship steering system 10 may include a steering tiller 14. As illustrated in Figure 1, the steering tiller 14 extends from a first end 16 to a second end 18 opposite the first end 16. The steering tiller 14 may be pivotably coupled to the ship propulsion unit 12. As illustrated in Figure 1, the steering tiller 14 is pivotably coupled to the ship propulsion unit 12 in close proximity to the second end 18 of the steering tiller 14. In various implementations, the steering tiller 14 may also be pivotably coupled to a driven assembly 28 of the electric actuator 20 in order to operably couple the ship propulsion unit 12 with the electric actuator 20 so that the operation of the electric actuator 20 facilitates the pivoting and / or turning of the ship propulsion unit 12 in order to steer the ship.

[0021] Referring further to Figure 1, the ship steering system 10 includes an electric actuator 20. The electric actuator 20 includes a motor 24. The motor 24 may include a stator 32 and a rotor 34 configured to rotate relative to the stator 32 about a rotor shaft 66 when the motor 24 is operating. The motor 24 is drive-engaged with an output shaft 22 so that the motor 24 can operate to drive the rotation of the output shaft 22 about a shaft 26. In some implementations, the electric actuator 20 includes a plurality of motors 24. For example, as illustrated in Figure 1, the electric actuator 20 includes a first motor 24A and a second motor 24B. In some implementations, the electric actuator 20 may include a plurality of output shafts 22. For example, in the embodiment of the electric actuator 20 illustrated in Figure 2, the electric actuator 20 includes a first output shaft 22A and a second output shaft 22B. In the exemplary embodiment, a first motor 24A is drive-engaged with a first output shaft 22A, and a second motor 24B is drive-engaged with a second output shaft 22B. The first output shaft 22A and the second output shaft 22B are coaxially aligned such that at least one of the first motor 24A and the second motor 24B is operable to drive the rotation of the first output shaft 22A and the second output shaft 22B around the axis 26.

[0022] Referring here to Figures 1 and 2, the electric actuator 20 includes a driven assembly 28. The driven assembly 28 is operably coupled to the output shaft 22 such that the rotation of the output shaft 22 by the motor 24 drives the axial movement of the driven assembly 28 relative to the output shaft 22 and the motor 24. In various implementations, the rotation of the output shaft 22 by the motor 24 in a first rotational direction drives the axial movement of the driven assembly 28 relative to the output shaft 22 and the motor 24 in the first axial direction, and the rotation of the output shaft 22 by the motor 24 in a second rotational direction opposite to the first rotational direction drives the axial movement of the driven assembly 28 relative to the output shaft 22 and the motor 24 in the second axial direction opposite to the first axial direction. Thus, during the operation of the electric actuator 20, the driven assembly 28 can reciprocate in the axial direction as the motor 24 drives the rotation of the output shaft 22 in the first and second rotational directions.

[0023] Referring further to Figures 1 and 2, the driven assembly 28 may include a nut tube 36. A central screw 38 fixedly coupled to the output shaft 22 may be housed within the nut tube 36. In other words, the central screw 38 may be positioned radially inward of the nut tube 36 within a hollow portion defined by the threaded interior of the nut tube 36. In various configurations, the nut tube 36 is translatable along the shaft 26 such that it is axially displaced relative to the central screw 38 in response to the motor 24 rotating the output shaft 22 to which the central screw 38 is fixedly coupled. In other words, the rotation of the output shaft 22 and the central screw 38 fixedly coupled to the output shaft 22 may cause the nut tube 36 to move axially while remaining stationary relative to the shaft 26.

[0024] In some embodiments, the nut tube 36 and the central screw 38 are components of a roller screw assembly 40 of the ship's steering system 10. For example, as illustrated in Figure 2, the roller screw assembly 40 includes a central screw 38 fixedly coupled to an output shaft 22, a nut tube 36 that receives the central screw 38 internally, and a plurality of rollers 42 radially disposed between the central screw 38 and the nut tube 36. The plurality of rollers 42 are configured to engage with the central screw 38 and the nut tube 36, so that the rotation of the central screw 38 by the output shaft 22 causes the rollers 42 to move the nut tube 36 axially relative to the central screw 38.

[0025] In the embodiment illustrated in Figure 2, the roller 42 has threads that engage with the central screw 38 and the corresponding threads of the nut tube 36. The threaded roller 42 is engaged so that the roller 42 rotates about an axis (not shown) parallel to the axis 26 and revolves planetarily around the axis 26 while the central screw 38 rotates. In some implementations, multiple rollers 42 are non-translatably connected to the central screw 38 of the roller screw assembly 40. In other words, the axial position of each of the multiple rollers 42 is fixed with respect to the central screw 38. An exemplary embodiment of the threaded planetary roller 42 is illustrated in Figure 4. In the exemplary embodiment, the threads of the roller 42 and the threads of the central screw 38 have a helix angle that can cause the roller 42 to skew under load. As illustrated in Figure 4, the roller 42 includes geared ends 44 corresponding to a toothed or geared interface 46 positioned on the central screw 38 to prevent skew. The roller screw assembly 40 is intended to include various types of rollers 42 (e.g., balls) in various mounting configurations. Furthermore, in some mounting configurations, the threads of the central screw 38 are intended to correspond directly to the threads of the nut tube 36.

[0026] Referring here to Figures 1 and 2, the driven assembly 28 includes a housing 48. In various configurations, the nut tube 36 is housed in and fixed to the housing 48. Thus, the housing 48 can translate along the shaft 26 together with the nut tube 36 in response to the motor 24 rotating the output shaft 22. In the embodiment illustrated in Figure 1, the entire roller screw assembly 40 is located within the housing 48. In various configurations, the output shaft 22 extends axially outward from the housing 48. As illustrated in Figure 1, a first output shaft 22A extends axially outward from the housing 48 in a first axial direction, and a second output shaft 22B extends axially outward from the housing 48 in a second axial direction opposite to the first axial direction.

[0027] Referring further to Figures 1 and 2, the housing 48 may be formed from a plurality of components that cooperate to form an enclosure that is sealed to prevent external contaminants, such as saltwater, from entering the enclosure in which the nut tube 36 is located. In an exemplary embodiment, the housing 48 includes a body 50 that extends circumferentially around the nut tube 36 and is fixed to the nut tube 36, a bushing 52 that receives an output shaft 22 extending through the body 50 and is coupled to the body 50 at its axial end to facilitate rotation of the output shaft 22, and a sealing portion 54, such as an O-ring, that extends radially between the output shaft 22 and the bushing 52, thereby the body 50, the bushing 52, the sealing portion 54, and the output shaft 22 cooperate to seal the enclosure defined by the housing 48. In the operation of an exemplary embodiment of the electric actuator 20, the rotation of the output shaft 22 causes the nut tube 36 and the housing 48 fixed to the nut tube 36 to move axially, thereby causing the body 50, bushing 52, and seal portion 54 to move axially relative to the output shaft 22. In order for the housing 48 to maintain a sealed enclosure, the seal portion 54 must maintain sufficient contact with the outer surface of the output shaft 22 as the housing 48 moves axially along the output shaft 22. Therefore, the axial range of the outer surface of the output shaft 22 to which the seal portion 54 must maintain contact during the operation of the electric actuator 20 may be cylindrical and smooth in order to ensure a consistent interface between the output shaft 22 and the seal portion 54. In some embodiments, the housing 48 is intended to include other sealing means, such as bellows, to adapt the movement of the housing 48 relative to the output shaft 22.

[0028] As illustrated in Figure 2, the housing 48 includes a body 50 extending circumferentially around the roller screw assembly 40, a first bushing 52A coupled to the body 50 near a first axial end of the body 50, a second bushing 52B coupled to the body 50 near a second axial end of the body 50 opposite the first axial end, and a first seal portion 54A and a second seal portion 54B coupled to the first bushing 52A and the second bushing 52B, respectively. The first output shaft 22A is fixedly coupled to a central screw 38 and extends axially outward in the first axial direction through the first bushing 52A. The second output shaft 22B is fixedly coupled to the central screw 38 and extends axially outward in the second axial direction through the second bushing 52B. To seal the enclosure defined by the housing 48, the first sealing portion 54A extends radially between the first bushing 52A and the output shaft 22, and the second sealing portion 54B extends radially between the second bushing 52B and the second output shaft 22B.

[0029] Referring here to Figures 1 and 3, the driven assembly 28 may include a pivot plate 56. The pivot plate 56 is pivotably coupled to the housing 48 and can be operable to pivot relative to the housing 48 about a pivot plate axis 58 which is parallel to the axis 26 around which the output shaft 22 rotates. As illustrated in Figures 1 and 3, the steering tiller 14 is pivotally coupled to the driven assembly 28 via a pivot connection with the pivot plate 56. In other words, the steering tiller 14 is pivotally coupled to the pivot plate 56 of the driven assembly 28. Thus, in the embodiment illustrated in Figures 1 and 3, the pivot plate 56 is operable to pivot relative to the housing 48 about the pivot plate axis 58, and the steering tiller 14 is operable to pivot relative to the pivot plate 56. In the embodiments illustrated in Figures 1 and 3, the steering tiller 14 is pivotably coupled to the ship's propulsion unit 12 near a second end 18 of the steering tiller 14, and pivotably coupled to a pivot plate 56 near a first end 16 of the steering tiller 14. The steering tiller 14, thus pivotably coupled to the ship's propulsion unit 12 and the driven assembly 28 of the electric actuator 20, enables control of the steering of the ship's propulsion unit 12 via the operation of the electric actuator 20, as further described herein.

[0030] Referring further to Figures 1 and 3, the electric actuator 20 includes a support structure 60. The support structure 60 can support various components of the electric actuator 20. For example, the support structure 60 can support the motor 24 and output shaft 22 of the electric actuator 20. In an exemplary embodiment, the motor 24 is housed by a support arm 62 of the support structure 60, which is offset axially from the housing 48. The motor 24 is housed by the support arm 62 such that axial movement of the motor 24 and rotational movement of the stator 32 of the motor 24 are prevented by the support arm 62. In some implementations, the support arm 62 of the support structure 60 prevents axial movement of the output shaft 22. The support arm 62 may have a bearing 64 coupled to the support arm 62 that supports the output shaft 22 and facilitates the rotation of the output shaft 22, as illustrated in Figures 1 and 3. In some embodiments, the support structure 60 may include a plurality of support arms 62. For example, in the embodiment illustrated in Figure 1, the support structure 60 includes a first support arm 62A and a second support arm 62B.

[0031] In various embodiments, the motor 24 of the electric actuator 20 is located outside the housing 48 that houses the nut tube 36. For example, in the embodiment illustrated in Figure 1, the first motor 24A is housed in the first support arm 62A of the support structure 60, and the motor 24 is axially offset from the housing 48 and located outside the housing 48. The electric actuator 20 of Figure 1 further includes a second motor 24B housed in the second support arm 62B of the support structure 60, which is positioned axially opposite to the first support arm 62A. The second motor 24B, like the first motor 24A, is axially offset from the housing 48 that houses the nut tube 36 and located outside the housing 48. In the illustrative embodiment, the first motor 24A and the second motor 24B are coaxial with the first output shaft 22A and the second output shaft 22B, so that the rotors 34 of the first output shaft 22A and the second output shaft 22B, as well as the first motor 24A and the second motor 24B, rotate about an axis 26. In some implementations, the motors 24 of the electric actuator 20 are positioned such that the rotor axis 66 around which the rotor 34 of the motor 24 rotates relative to the stator 32 is radially offset from the axis 26 around which the output shaft 22 rotates. For example, in the embodiment illustrated in Figure 3, the rotor axis 66 of the first motor 24A and the second motor 24B is radially offset from the axis 26 around which the first output shaft 22A and the second output shaft 22B rotate. The operability of the electric actuator 20 having this arrangement of motors 24 can be achieved by utilizing an intermediate structure that transmits the rotational force of the motors 24 to the offset output shafts 22. For example, in the embodiment illustrated in Figure 3, a first motor 24A is drivably connected to a first output shaft 22A via a gear set 68, and a second motor 24B is drivably connected to a second output shaft 22B via a belt 70.The embodiment illustrated in Figure 3 includes, exemplarily, a gear set 68 and a belt 70, but it should be understood that the first motor 24A and the second motor 24B can be drivably connected to the first output shaft 22A and the second output shaft 22B by intermediate structures of various types and combinations of types (e.g., the first gear set and the second gear set 68, the first belt and the second belt 70, etc.).

[0032] Referring here to Figures 1 and 3, the electric actuator 20 may include a mounting shaft 72. The mounting shaft 72 can be coupled to a support structure 60 and is configured to facilitate the pivotal movement of the support structure 60, the motor 24, the output shaft 22, and the housing 48 of the electric actuator 20 around a pivot shaft 74. The pivot shaft 74 may extend parallel to the shaft 26 around which the output shaft 22 rotates and / or the pivot plate shaft 58 around which the pivot plate 56 rotates relative to the housing 48. As illustrated in Figures 1 and 3, the pivot shaft 74 is radially offset from the shaft 26 around which the output shaft 22 pivots and the pivot plate shaft 58. In various implementation configurations, the mounting shaft 72 is coupled to a mounting structure (not shown) of the ship's steering system 10, such as an engine mounting bracket, and is configured to facilitate the pivotal movement of the support structure 60, motor 24, output shaft 22, and housing 48 around the pivot axis 74 by rotating relative to the mounting structure, or by providing a reinforcing interface such as a rotating stationary cylindrical surface on which the support structure 60, motor 24, output shaft 22, and housing 48 rotate relatively together as a single unit.

[0033] In various implementations, the mounting shaft 72 is elongated in the axial direction of the pivot shaft 74, and the pivot shaft 74 extends through the mounting shaft 72 or within a hollow portion defined by the mounting shaft 72. In some implementations, the electric actuator 20 may include multiple mounting shafts 72, such as a first mounting shaft 72A and a second mounting shaft 72B extending from a first support arm 62A and a second support arm 62B of the support structure 60 to the mounting structure, respectively. In various implementations, the ship propulsion unit 12 is operable to pivot around the pivot shaft 74, for example, when adjusting the ship propulsion unit 12 up or down.

[0034] In some implementations, the support structure 60 may include a front housing 76 that extends axially between a first support arm 62A and a second support arm 62B of the support structure 60. In various implementations, the front housing 76 may be positioned such that a housing 48 housing a nut tube 36 is positioned between the front housing 76 of the support structure 60 and the steering tiller 14 of the ship's steering system 10. In some implementations, the front housing 76 is positioned forward of the housing 48 housing the nut tube 36. The front housing 76 may support additional components of the electric actuator 20, such as a sensor 78 and lights 80. In an exemplary implementation, the front housing 76 may support a linear sensor 82 configured to detect the translational position of the housing 48 along the axis 26. In some embodiments, the front housing 76 may support one or more lights 80 configured to act in response to the operating state of the electric actuator 20 to indicate, for example, the operating status of the electric actuator 20, the diagnosis of the electric actuator 20, and / or various other states.

[0035] In an exemplary embodiment of the ship steering system 10 illustrated in Figure 1, the ship steering system 10 includes a ship propulsion unit 12. A steering tiller 14 is pivotably coupled to the ship propulsion unit 12 in proximity to a second end 18 of the steering tiller 14. An electric actuator 20 includes a housing 48. A pivot plate 56 is pivotably coupled to the housing 48 and is operable to pivot relative to the housing 48 about a pivot plate axis 58. The steering tiller 14 is pivotably coupled to the pivot plate 56 in proximity to a first end 16 of the steering tiller 14, thereby allowing the pivot plate 56 to pivot relative to the housing 48 about a pivot plate axis 58, and the steering tiller 14 is operable to pivot relative to the pivot plate 56. A first output shaft 22A extends axially outward from the housing 48 in a first axial direction. The second output shaft 22B extends axially outward from the housing 48 in the second axial direction opposite to the first axial direction. The first motor 24A is located outside the housing 48 within the first support arm 62A of the support structure 60 and is drive-engaged with the first output shaft 22A, thereby enabling the first motor 24A to operate to drive the rotation of the first output shaft 22A about axis 26. The second motor 24B is located outside the housing 48 within the second support arm 62B of the support structure 60 and is drive-engaged with the second output shaft 22B, thereby enabling the second motor 24B to operate to drive the rotation of the second output shaft 22B about axis 26. The roller screw assembly 40 is located inside the housing 48 and is coupled to the first output shaft 22A and the second output shaft 22B. The roller screw assembly 40 includes a nut tube 36 fixed to the housing 48. The roller screw assembly 40 further includes a central screw 38 which is received by a nut tube 36.The nut tube 36 is axially translatable with respect to the central screw 38 in response to at least one of the first motor 24A that drives the rotation of the first output shaft 22A and the second motor 24B that drives the rotation of the second output shaft 22B. The mounting shaft 72 extends axially between the first support arm 62A and the second support arm 62B.

[0036] In the operation of an exemplary embodiment of the ship steering system 10 illustrated in Figure 1, a steering command prompts the first motor 24A and the second motor 24B to drive the rotation of the first output shaft 22A and the second output shaft 22B around the axis 26. The rotation of the first output shaft 22A and the second output shaft 22B causes a central screw 38 extending axially between them to rotate around the axis 26, driving the axial movement of the nut tube 36. The housing 48, fixedly coupled to the nut tube 36, translates axially with the nut tube 36. This translation of the housing 48 results in the rotation of the ship's propulsion unit 12 because (1) the pivot plate 56 is pivotably coupled to the housing 48 and is operable to pivot relative to the housing 48 about the pivot plate shaft 58; (2) the steering tiller 14 is pivotably coupled to the pivot plate 56 in close proximity to the first end 16 of the steering tiller 14; (3) the steering tiller 14 is pivotably coupled to the ship's propulsion unit 12 in close proximity to the second end 18 of the steering tiller 14; and (4) the support structure 60, the first motor 24A and the second motor 24B, the first output shaft 22A and the second output shaft 22B, the roller screw assembly 40, and the housing 48 are operable to pivot about the pivot shaft 74 extending through the mounting shaft 72. Thus, in full-stroke operation of the electric actuator 20 that controls the ship's propulsion unit 12, (1) the nut tube 36 and housing 48 are translated in the axial direction, (2) the pivot plate 56 pivots relative to the housing 48 about the pivot plate shaft 58 such that the portion of the pivot plate 56 to which the steering tiller 14 is pivotally connected moves along an arc, (3) the steering tiller 14 pivots relative to the pivot plate 56, (4) the steering tiller 14 pivots relative to the ship's propulsion unit 12, and (5) the support structure 60, the first motor 24A and the second motor 24B, the first output shaft 22A and the second output shaft 22B, the roller screw assembly 40, and the housing 48 pivot about the pivot shaft 74.As used herein, “full stroke actuation” of the electric actuator 20 should be understood as the actuation of the electric actuator 20 that facilitates the axial movement of the nut tube 36 from a first axial end limit of the nut tube 36 to a second axial end limit of the nut tube 36. In various implementations, limit switches may be used to set the axial end limits, which in some embodiments may be adjustable to allow for modification of the axial length between the axial end limits.

[0037] The ship steering system 10 and the electric actuator 20 of the ship steering system 10 of this disclosure may offer several advantages. Firstly, fixing the motor 24 axially to the support arm 62 of the electric actuator 20 reduces the movement of the motor cable (i.e., the cable for electrical connections) during the steering of the ship propulsion unit 12, which improves the durability of the motor cable. Secondly, the electric actuator 20 having a first motor 24A and a second motor 24B advantageously allows the ship steering system 10 to continue operating if either the first motor 24A or the second motor 24B stops working. In particular, having two motors 24, each capable of operating to apply twice the amount of torque required to operate the ship steering system 10, can protect against failure of either the first motor 24A or the second motor 24B. Thirdly, the electric actuator 20 having the motor 24 located outside the housing 48 that houses the nut tube 36 reduces the required area of ​​the electric actuator 20 in the region where the electric actuator 20 is axially aligned with the ship propulsion unit 12. This is particularly advantageous because it provides an additional gap for raising the ship's propulsion unit 12 out of the water for adjustment or tilting.

[0038] It should be understood that modifications and alterations can be made to the aforementioned structures without departing from the concepts of this disclosure, and further, that such concepts are intended to be encompassed by the following claims unless expressly otherwise provided in their language. [Explanation of symbols]

[0039] 10. Marine Steering Systems 12. Ship propulsion units 14 Steering tiller 16 First end 18. Second end 20 Electric Actuators 22 Output shaft 22A First output shaft 22B Second output shaft 24 motors 24A First motor 24B Second motor 26 axes 28 Driven Assembly 30 Engine 32 Stator 34 rotors 36 Nut Tube 38 Center screw 40 Roller Screw Assembly 42 Laura 44 End with pull 46 Geared Interface 48 Housing 50 Main Unit 52 Bushing 52A First Bushing 52B Second Bushing 54 Seal part 54A First seal section 54B Second seal section 56. Pivoting plate 58 Pivot plate shaft 60 Support structure 62 Support Arms 62A First support arm 62B Second support arm 64 Bearings 66 Rotor shaft 68 Gear Set 70 belt 72 Mounting shaft 72A First mounting shaft 72B Second mounting shaft 74 Pivot axis 76 Front Housing 78 sensors 80 Lights 82 Linear Sensors

Claims

1. A ship steering system, Ship propulsion unit and A steering tiller having a first end and a second end opposite to the first end, and being pivotably coupled to the ship's propulsion unit in close proximity to the second end, It is an electric actuator, Output shaft, A motor that drives the rotation of the output shaft around the axis, and An electric actuator comprising a driven assembly, the driven assembly being pivotably coupled to the steering tiller near the first end and operably coupled to the output shaft, such that the rotation of the output shaft by the motor drives the axial movement of the driven assembly relative to the output shaft and the motor in order to steer the ship's propulsion unit via the steering tiller, A ship steering system equipped with the following features.

2. The driven assembly, Housing and A nut tube housed in the housing and fixed to the housing, receiving a central screw internally that is fixedly coupled to the output shaft, the nut tube being translatable along the shaft in response to the motor rotating the output shaft, The ship steering system according to claim 1, comprising:

3. The aforementioned ship steering system is a roller screw assembly, The central screw fixedly connected to the output shaft, The nut tube, which receives the central screw inside, A ship steering system according to claim 2, comprising a roller screw assembly comprising a plurality of rollers, which are radially disposed between the central screw and the nut tube and configured to engage with the central screw and the nut tube.

4. The ship steering system according to claim 3, wherein the plurality of rollers are connected to the central screw in a way that prevents translation, such that the axial position of each of the plurality of rollers is fixed with respect to the central screw.

5. The ship steering system according to claim 2, wherein the motor is located outside the housing.

6. The ship steering system according to claim 1, wherein the motor is offset in the axial direction from the whole of the driven assembly.

7. The ship steering system according to claim 6, wherein the motor and the output shaft are coaxially aligned such that the motor and the output shaft rotate about the axis.

8. The ship steering system according to claim 1, wherein the motor includes a stator and a rotor configured to rotate relative to the stator about a rotor axis which is radially offset from the axis around which the output shaft rotates.

9. The ship steering system according to claim 8, wherein the motor is drivably connected to the output shaft via a gear set.

10. The ship steering system according to claim 8, wherein the motor is drivably connected to the output shaft via a belt.

11. The driven assembly, A pivot plate pivotably coupled to the housing and operable to pivot relative to the housing about a pivot plate axis parallel to the axis around which the output shaft rotates, wherein the steering tiller is pivotably coupled to the driven assembly via a pivot coupling to the pivot plate such that the pivot plate is operable to pivot relative to the housing about the pivot plate axis, and the steering tiller is operable to pivot relative to the pivot plate.

12. The aforementioned electric actuator The ship steering system according to claim 11, further comprising a support structure having a support arm that is offset in the axial direction from the housing and configured to prevent axial movement of the output shaft, wherein the motor is housed by the support arm such that axial movement of the motor relative to the support arm is prevented.

13. The aforementioned electric actuator The ship steering system according to claim 12, further comprising a mounting shaft connected to the support structure, extending parallel to the axis, and configured to facilitate the pivotal movement of the support structure, the motor, the output shaft, and the housing around a pivot axis that is radially offset from the axis and the pivot plate axis.

14. The ship steering system according to claim 13, wherein the full stroke operation of the electric actuator facilitates the pivot movement of the support structure, the motor, the output shaft, and the housing around the pivot axis, the pivot movement of the pivot plate relative to the housing around the pivot plate axis, the pivot movement of the steering tiller relative to the pivot plate, and the pivot movement of the steering tiller relative to the ship propulsion unit.

15. The ship steering system according to claim 1, wherein the ship propulsion unit is an engine.

16. An electric actuator for a ship steering system, Housing and A first output shaft extending axially outward from the housing in the first axial direction, A first motor, which is located outside the housing and is drive-engaged with the first output shaft such that the first motor can operate to drive the rotation of the first output shaft about an axis, A roller screw assembly disposed within the housing and coupled to the first output shaft, wherein the roller screw assembly comprises a nut tube fixed to the housing and a central screw received by the nut tube, the nut tube being axially translatable in response to the first motor rotating the first output shaft and the central screw about the axis, An electric actuator equipped with the following features.

17. A second output shaft is coupled to the roller screw assembly and extends axially outward from the housing in a second axial direction opposite to the first axial direction, A second motor is located outside the housing and is drive-engaged with the second output shaft, The electric actuator according to claim 16, further comprising the above.

18. The electric actuator according to claim 16, further comprising a pivot plate which is pivotably coupled to the housing and is operable to pivot relative to the housing about a pivot plate axis which is parallel to the axis around which the first output shaft rotates, wherein the pivot plate is configured to pivotably couple a steering tiller of the ship steering system to the pivot plate.

19. The electric actuator according to claim 16, wherein the rotation of the first output shaft promotes the axial translation of the nut tube relative to the first motor.

20. A ship steering system, Ship propulsion unit and A steering tiller having a first end and a second end opposite to the first end, and being pivotably coupled to the ship's propulsion unit in close proximity to the second end, It is an electric actuator, housing, A pivot plate is pivotably coupled to the housing and is operable to pivot relative to the housing about a pivot plate axis, wherein the steering tiller is pivotably coupled to the pivot plate in close proximity to the first end of the steering tiller such that the pivot plate is operable to pivot relative to the housing about a pivot plate axis, and the steering tiller is operable to pivot relative to the pivot plate, A first output shaft extending axially outward from the housing in the first axial direction, A second output shaft extending axially outward from the housing in a second axial direction opposite to the first axial direction, A first motor, which is located outside the housing and is drive-engaged with the first output shaft so as to be operable to drive the rotation of the first output shaft about an axis, A second motor, which is located outside the housing and is drive-engaged with the second output shaft such that the second motor can operate to drive the rotation of the second output shaft about the axis, An electric actuator comprising a roller screw assembly disposed within the housing and coupled to the first output shaft and the second output shaft, wherein the roller screw assembly comprises a nut tube fixed to the housing and a central screw received by the nut tube, and the nut tube is configured to translate axially along the shaft in response to the rotation of the central screw via at least one of the first motor driving the rotation of the first output shaft and the second motor driving the rotation of the second output shaft, A ship steering system equipped with the following features.

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