Screw and nut transmission system

Abstract

Improve the screw nut transmission system. 【Solution means】The present invention relates to a screw nut transmission system, and this screw nut transmission system is - a first element (10 or 20), - a second element (20 or 10) arranged to rotate about an axis (X), and when the second element (20 or 10) rotates in cooperation with the first element (10 or 20), the first element (10 or 20) moves along this axis (X) in a translational motion, the second element (20 or 10) A screw nut transmission system comprising When the first element (10 or 20) is a nut, the second element (20 or 10) is a screw, and when the first element is a screw, the second element is a nut, The screw nut transmission system is - provided with a fixed casing (60) that at least partially surrounds the first element (10 or 20) and the second element (20 or 10) and has a groove (90) defined by a plurality of side surfaces, - provided with a part arranged such that the first element (10 or 20) performs a translational motion within the groove (90), In the screw nut transmission system, the screw nut transmission system is - provided with a first magnet (40) connected to each of this part and the fixed casing (60), - one or both of a contact surface made of a ferromagnetic material and a second magnet, One or both of the contact surface and the second magnet are respectively connected to the fixed casing and this part, One or both of the contact surface and the second magnet cooperate with the first magnet (40) to prevent the rotation of the first element (10 or 20), Comprising the contact surface (51) and one or both of the second magnets Characterized by.

Description

Technical Field

[0001] The present invention relates to a screw-nut transmission system, particularly for high-precision positioning applications, i.e., applications where the positioning accuracy is 50 μm or less, particularly 10 μm or less, for example 1 μm or less. More specifically, the present invention relates to a screw-nut transmission system that eliminates angular backlash by utilizing magnetic force.

Background Art

[0002] One of the conventional solutions for converting rotational motion into translational (or linear) motion or vice versa is a screw-nut transmission system.

[0003] Generally, a screw-nut transmission system basically comprises - a first element, and - a second element that cooperates with the first element and is arranged to rotate about an axis, and when the first element rotates, the second element performs a translational motion along the second element. and basically includes these.

[0004] When the first element is a nut and the second element is a screw, the nut performs a translational motion along the rotating screw.

[0005] When the first element is a screw and the second element is a nut, while the nut rotates around the screw, the screw performs a translational motion along its main axis.

[0006] By adding balls between the first element and the second element, the screw-nut system is called a "ball screw system". With the balls, transmission can be achieved by rolling instead of sliding or friction as in the case of a screw-nut system.

[0007] In a screw-nut transmission system, in order to convert rotational motion into translational (or linear) motion and obtain linear actuation in one direction, for example, along the X direction, it is desirable or necessary to reduce or block the rotational freedom dΘX of the element performing the translational motion around the X axis.

[0008] In fact, this anti-rotation condition for elements moving in translational motion affects the positioning accuracy of these elements. For an angular tolerance dΘX, the positioning error can be calculated using the following formula.

[0009]

number

[0010] P is the pitch value (of either the screw or the nut, or both).

[0011] As a result, in applications requiring high positioning accuracy, it may be necessary to limit or even eliminate dΘX.

[0012] Solutions exist to limit or eliminate dΘX.

[0013] In one of these solutions, the nut is the first element, and as the screw rotates around its principal axis, the nut translates along the screw. In this solution, the transmission system comprises a fixed casing surrounding the nut and screw, and this casing has grooves defined by its sides.

[0014] At least a portion of the nut undergoes translational motion within the groove.

[0015] In this solution, the screw-nut transmission system typically uses a pin attached to the nut as an anti-rotation device. For the pin to reduce or prevent the nut from rotating, a gap must exist between the pin and the groove.

[0016] A conventional solution to absorb the gap between the pin and the groove is, for example, to use a torsion spring between the nut and the shell to apply an angular preload.

[0017] This ensures that the pin is always in contact with one side of the groove. If there is no play compensation in the groove, when the second element rotates in the opposite direction and the first element moves in the opposite direction, the pin will come into contact with the other side of the groove and stop, resulting in an error called "hysteresis."

[0018] When there are balls between the screw and nut, the transmission system also includes rolling guides, such as ball bearings, to guide the movement of the nut within the groove. This allows the nut to roll on one side of the groove without friction, thus reducing or eliminating a phenomenon called "stick-slip" (or "slipstick"), especially in precise positioning.

[0019] The presence of a torsion spring for angular backlash adjustment introduces certain disadvantages, particularly the volume occupied by the spring. This disadvantage can become significant when this solution is used in very compact devices, such as, but not limited to, embedded devices.

[0020] Furthermore, the presence of torsion springs can lead to uncontrollable friction between the spring coils and various components of the system. The coils may overlap when folded, resulting in uncontrollable friction.

[0021] In addition, the preload force may change during the nut stroke. In the case of a tension spring, the force difference is equal to the product of the spring's stiffness and elongation. This change can affect positioning accuracy depending on the load conditions.

[0022] Finally, using a torsion spring requires significant force to adjust the backlash over the entire travel of the nut. This affects at least one of the following: the size of the actuarial part (e.g., a linear actuator) connected to the screw-nut transmission system, the required driving torque, the energy consumption of the system, and the volume used.

[0023] Patent Document 1 (US9273766) describes an electric operating unit equipped with a ball screw mechanism that converts the rotational motion of an electric motor into linear axial motion of a drive shaft. This system has a magnet on a pin and, in conjunction with a sensor such as a Hall effect sensor, can detect the position of the shaft from the rotation angle of the pin.

[0024] Patent Document 2 (JP2004182063) describes an automotive screw nut system that uses magnetic force to prevent the nut from rotating.

[0025] Patent Document 3 (JP2021035311) relates to a screw nut system. (In the described system) it uses the magnetic interaction between an internal magnet and an external magnet to prevent the rotation of the nut and the piston associated with it.

Prior Art Documents

Patent Documents

[0026]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0027] One object of the present invention is to provide a screw nut transmission system that is not subject to the limitations of known screw nut transmission systems.

[0028] Another object of the present invention is to provide a screw nut transmission system suitable for high-precision positioning applications.

[0029] Furthermore, an object of the present invention is to provide a screw nut transmission system that is smaller in size compared to known systems.

[0030] Furthermore, an object of the present invention is to provide a screw-nut transmission system that is sized for use in very small (compact) devices, such as embedded devices, for example, as a non-limiting example.

[0031] Another object of the present invention is to provide a screw nut transmission system that can better control friction than known systems.

[0032] Furthermore, an object of the present invention is to provide a screw-nut transmission system that allows for angular play of the moving element while achieving at least one of the following: minimizing energy requirements, ensuring a constant load state over the entire stroke of the moving element, ensuring an equistatic stress state, and minimizing the impact on the system volume. [Means for solving the problem]

[0033] The present invention achieves these objectives, particularly through the screw-nut transmission system described in claim 1.

[0034] The screw nut transmission system is - The first element, - A second element positioned to rotate around an axis, which works in cooperation with the first element so that when the second element rotates, the first element moves so that it performs translational motion along its axis. It comprises such that the first element is a nut and the second element is a screw, and the first element is a screw and the second element is a nut, The screw nut transmission system is - A fixed casing comprising at least partially enclosing the first and second elements and having a groove defined by its side, the portion comprising which the first element is positioned to perform translational motion within the groove.

[0035] In this invention, the system also includes a first magnet connected (directly or indirectly) to the aforementioned part and to the fixed casing.

[0036] In this invention, one or both of the contact surface and the second magnet, which are made of a ferromagnetic material, are connected to the aforementioned part and the fixed casing, respectively, and this surface and one or both of the second magnet cooperate with the first magnet to prevent the rotation of the first element.

[0037] This solution has advantages over conventional technologies, particularly in that it is a screw-nut transmission system suitable for high-precision positioning applications.

[0038] This solution also has advantages over conventional technologies in that it is smaller in size than known systems and, in particular, has a volume (size) that is suitable for use in very miniaturized devices, such as implantable devices, for example, in non-limiting examples.

[0039] An embodiment in which the first magnet is connected to a portion of the first element and the contact surface of the ferromagnetic material, and the second magnet is connected to a fixed casing, has the advantage of being even smaller in volume than an embodiment in which the first magnet is connected to a fixed casing and one or both of the contact surface of the ferromagnetic material and the second magnet are connected to a portion of the first element. In fact, in this second embodiment, the first magnet may have larger dimensions than in the first embodiment, but this affects the overall diameter of the screw nut transmission system.

[0040] Furthermore, in both embodiments, the presence of the first magnet and the surface made of a ferromagnetic material, and the presence of one or both of the second magnet, allows for better control of friction than in known systems.

[0041] In either case, the screw-nut transmission system according to the present invention minimizes energy requirements, incorporates the angular play of the translationally moving elements, ensures a constant load state throughout the entire stroke of the translationally moving elements, maintains an equistatic pressure state, and minimizes the impact on the system's volume.

[0042] In one embodiment, the screw nut transmission system includes a guide device that guides the displacement of an element moving in translational motion.

[0043] In one embodiment, the guide device is a rolling element guide device (rolling transmission mechanism). In this embodiment, there is a ball between the screw and the nut.

[0044] In one embodiment, the rolling elements are nonmagnetic and, for example, are formed of ceramic in a non-limiting manner.

[0045] In one embodiment, the rolling elements are formed from a magnetizable material such as magnetizable steel.

[0046] In one embodiment, the rolling element guide (guide device) is a ball bearing.

[0047] In one embodiment, the rolling element guide device is At least a portion of the (outer ring) is an outer ring arranged to roll on the contact surface of the ferromagnetic material and on one or both of the second magnet, or The rolling element guide device is The outer ring is connected to a sleeve, and at least a portion of it is arranged to roll on one or both of the ferromagnetic material contact surface and the second magnet, It is.

[0048] In one embodiment, the first magnet is connected to an outer ring or sleeve. In this embodiment, the first magnet is a rotating magnet, i.e., a magnet arranged to rotate around an axis during operation of the screw nut transmission system.

[0049] In one embodiment, a portion arranged to translate within a groove is connected to a rod (e.g., a pin, stud, etc.) arranged to translate within the groove and transport a first magnet.

[0050] In one embodiment, the rolling element guide device is transported by this rod.

[0051] In one embodiment, the guide device is a fixed sliding bearing that at least partially surrounds the screw and nut (sliding drive). In this case, the sliding bearing may include one or both of the contact surface and the second magnet.

[0052] In this case, in one embodiment, one or both of the contact surface and the second magnet need to have a low coefficient of friction, for example, less than 0.15, preferably equal to 0.05.

[0053] In one embodiment, the groove lies on a plane, and one or both contact surfaces of the ferromagnetic material and the second magnet are substantially perpendicular to this plane.

[0054] In one embodiment, the dimension parallel to the translational direction of the first element on the contact surface of the ferromagnetic material and on one or both of the second magnet is less than 15 μm, preferably less than 10 μm, for example, 1 μm.

[0055] In one embodiment, the contact surface, consisting of one or both of the ferromagnetic material and the second magnet, has a roughness (Ra) of less than 1 μm, preferably less than 0.8 μm, for example, 0.2 μm.

[0056] In one embodiment, the fixed casing comprises a plate (having a contact surface made of a ferromagnetic material and a second magnet, or both) and a mounting surface for fixing the plate to the fixed casing.

[0057] In one embodiment, the substrate is made of a ferromagnetic material.

[0058] In one embodiment, one or both of the contact surface and the second magnet are perpendicular to the mounting surface.

[0059] Instead of an embodiment in which the first magnet is attached to a fixed casing and one or both of the contact surface and the second magnet, which are made of a ferromagnetic material, are attached to a portion of the first element, the first magnet is positioned on the casing, for example, near a rolling plate that is not necessarily ferromagnetic, and one or both of a portion of the first element and a portion of the guide device (for example, one or both of the outer ring and sleeve if the guide device is a ball bearing) are formed of a magnetic material.

[0060] The present invention also relates to a rotary stroke bearing device, and this rotary stroke bearing device is - The transmission system according to the present invention, - A component (e.g., a lens) connected to the first element and thus arranged to move with translational motion, - To prevent the rotation of the first element, and thus prevent the rotation of the part, a contact surface made of a ferromagnetic material cooperates with the first magnet. It is equipped with.

[0061] Several examples of the embodiment of the present invention are shown in the description, which is illustrated by the accompanying drawings. [Brief explanation of the drawing]

[0062] [Figure 1] Figure 1 is a perspective view of a linear actuator equipped with a screw-nut transmission system, comprising a translationally moving nut, a rotating screw, a ball bearing, and a first rotating magnet, according to one embodiment of the present invention. [Figure 2] Figure 2 shows a longitudinal cross-section of the linear actuator shown in Figure 1. [Figure 3] Figure 3 shows a more detailed view of Figure 2. [Figure 4] Figure 4 shows a cross-section of Figure 1. [Figure 5] Figure 5 shows the bottom view of a linear actuator equipped with a screw-nut transmission mechanism, comprising a linearly moving nut, a rotating screw, a ball bearing, and a first non-rotating magnet, according to another embodiment of the present invention. [Figure 6] Figure 6 shows a side view of the linear actuator shown in Figure 5. [Figure 7] Figure 7 shows a cross-sectional view of the linear actuator shown in Figure 6. [Figure 8] Figure 8 shows a cross-section of the linear actuator shown in Figure 7 along the AA axis. [Figure 9] Figure 9 shows a longitudinal section of a perspective view of another linear actuator comprising a screw-nut transmission mechanism, a translationally moving nut, a rotating screw, a sliding bearing, and a translationally moving first magnet, according to another embodiment of the present invention. [Figure 10] Figure 10 shows a longitudinal cross-section of the linear actuator shown in Figure 9. [Figure 11] Figure 11 shows a longitudinal section of a perspective view of another linear actuator comprising a screw-nut transmission mechanism, a rotating nut, a translationally moving screw, a sliding bearing, and a translationally moving first magnet, according to another embodiment of the present invention. [Modes for carrying out the invention]

[0063] For the sake of explanation, the following description will be based on the magnetic force between (1) the magnet and the ferromagnetic support. However, it should be understood that the present invention is not limited to such magnetic forces and also includes (alternatively or additionally) the magnetic force between the first magnet and the second magnet.

[0064] For simplicity, the following explanation will use a screw-nut system as an example, in which the first magnet is connected to the first element (the part undergoing translational motion), and the contact surface made of ferromagnetic material is connected to a fixed casing.

[0065] However, it should be understood that the present invention is not limited to such embodiments and includes all screw-nut transmission systems as defined in the claims.

[0066] For example, in another embodiment not shown in the figures, the first magnet is connected to a fixed casing, and the contact surface made of ferromagnetic material is connected to a part of the first element. In yet another embodiment, the first magnet may be located near rolling plates that are not necessarily made of ferromagnetic material, and one or both of the part of the first element and the part of the guide device (for example, if the guide device is a ball bearing, one or both of the outer ring and the sleeve) may be made of ferromagnetic material.

[0067] In yet another embodiment, the first magnet may have larger dimensions than in the first embodiment, which affects the overall diameter of the screw nut transmission system.

[0068] Figure 1 shows a perspective view of a linear actuator 1 equipped with a screw-nut transmission system according to one embodiment of the present invention. Figure 2 shows a longitudinal cross-section of the linear actuator 1 (linear motion mechanism 1) shown in Figure 1. Figure 3 shows details of Figure 2. Figure 4 shows a cross-section of Figure 1.

[0069] In the embodiments shown in Figures 1 to 4, the screw-nut transmission system comprises a nut 10 that translates along the axis X (for example, shown in Figure 2) of a screw 20 that rotates around the axis X by a motor M (which is reduced by a reduction gear R if necessary). The nut 10 is connected to a head T that also translates.

[0070] Linear actuator 1 can be used in devices such as implantable devices. Other examples include linear actuators that can be assembled in parallel to form tripods or hexagons to position components such as mirrors, lenses, and semiconductor wafers, or to guide surgical instruments that require high-precision operation.

[0071] In the embodiments shown in Figures 1 to 4, the transmission system comprises a fixed casing 60 surrounding a nut 10 and a screw 20. In this embodiment, there is a ball between the screw 20 and the nut 10. In this embodiment, the casing 60 is not integrally molded but comprises multiple parts, including internal components 61. In the embodiments shown in Figures 1 to 4, the casing also comprises an optional radial force-receiving section 62. In the embodiments shown in Figures 1 to 4, this section 62 is a ball cage (for example, a ball is visible in Figure 4) positioned to move halfway along the nut in a rotary screw configuration.

[0072] The casing 60, and in particular its internal components 61, is provided with a groove 90 defined by its side. A portion of the nut 10 is positioned to translate along the X-axis along this groove 90.

[0073] In the embodiments shown in Figures 1 to 4, the transmission system includes a rod 30 (e.g., a pin or stud) substantially perpendicular to the X-axis. Since this pin 30 is integrated with the nut 10, it also translates along the X-axis within the groove 90. In the embodiments shown in Figures 1 to 4, this pin 30 is inserted into the cavity of the nut 10.

[0074] In the embodiments shown in Figures 1 to 4, this rod 30 is used to support the first magnet 40 and the guide device, which in this case is a ball bearing 80.

[0075] However, in other embodiments, one or both of the first magnet 40 and the guide device are directly supported by a portion of the nut 10 that moves within the groove 90.

[0076] The guide device is used to guide the movement of a portion of the nut 10 (and the rod 30 in the embodiments shown in Figures 1 to 4) within the groove 90.

[0077] As shown in Figure 4, the ball bearing 80 is Inner ring 82 (static in this embodiment) and Outer ring 83 (which is dynamic in this embodiment and rotates in particular around the Y axis), The rolling elements 81 (multiple balls in Figures 1 to 4) held between the outer ring 83 and the inner ring 82 The system includes the following: In one embodiment, the static wheel comprises two separate, interconnected parts, namely a core and a cone, which is generally driven on the core and determines the desired clearance within the bearing. In another embodiment, the static wheel comprises a single part, namely a core (without a cone). In this case, the system according to the present invention has the advantage of allowing play in the bearing, as play is incorporated.

[0078] In some cases, a cage is used to create space between the multiple rolling elements 81 in the wheel.

[0079] The number of contact points (for example, if the rolling elements are balls) or contact lines (for example, if the rolling elements are rollers) between the rolling elements and the ring may vary depending on the type of bearing. In the embodiments shown in Figures 1 to 4, the bearing 80 is a deep groove bearing. In another embodiment (not shown), the bearing 80 is a four-point contact ball bearing. In this case, the system according to the present invention provides a ball bearing with reduced clearance.

[0080] In one embodiment shown in Figures 1 to 4, the rolling elements are non-magnetic or have low permeability. For example, but not limited to these, they are made from ceramic, which eliminates the need to apply lubricant to the bearing 80. By using non-magnetic or low-permeability rolling elements, it is possible to prevent the magnetization of the rolling elements from interfering with the operation of the system according to the present invention. However, the system according to the present invention will also function with magnetizable rolling elements, such as magnetizable steel rolling elements.

[0081] As shown in Figure 4, the ball bearing 80 in this embodiment includes an (outer) sleeve 84 connected to an outer ring 83 and thus rotating around the Y-axis.

[0082] In the embodiments shown in Figures 1 to 4, the screw nut transmission system includes a first magnet 40 connected via a rod 30 to a portion of a nut 10 moving within a groove 90. In this embodiment, the first magnet 40 is integrated with the dynamic portion of the bearing 80, particularly the sleeve 84, and is therefore arranged to rotate around the Y-axis.

[0083] In one embodiment, one or both of the first and second magnets are permanent magnets. In one embodiment, one or both of the first and second magnets are magnetized along the X-axis. In one embodiment, one or both of the first and second magnets are substantially cylindrical.

[0084] The present invention comprises a contact surface 51 made of a ferromagnetic material (exemplary and not limited to iron, an iron alloy, or a magnetizable steel) connected to a fixed casing 60. In the embodiments shown in Figures 1 to 4, this contact surface 51 belongs to a plate 50 connected to the fixed casing 60, for example, via one or more screws V. In another embodiment, this contact surface 51 belongs directly to the fixed casing 60, although it is not shown. In yet another embodiment, the plate 50 and the fixed casing 60 form a single component.

[0085] In this invention, the contact surface 51 works in cooperation with the first magnet 40 to prevent the nut 10 from rotating.

[0086] In the embodiments shown in Figures 1 to 4, the translational portion of the nut 10 within the groove 90 and one side of the groove 90 are indirectly made, for example, via one or both of the rod 30 and the guide device 80. In the embodiments shown in Figures 1 to 4, the sleeve 84 of the guide device 80 is in contact with the plate 50. If the sleeve 84 is absent, the wheel 83 is capable of rolling on the plate 50. In this embodiment, the groove 90 is a gap and does not function as a rolling support. In the case of a sliding bearing (Figures 9 to 11), one side of the groove can be considered the contact surface.

[0087] In one embodiment, as shown in Figure 4, for example, at least one dynamic part of the guide device (outer sleeve 84 in the embodiments of Figures 1 to 4) is in direct contact C with a portion of the contact surface 51. Thus, the outer sleeve 84 rolls on this contact surface 51.

[0088] In one embodiment, for example, as shown in Figure 4, there is a distance d (air gap) between the first magnet 40 and the contact surface 51.

[0089] Due to the magnetic attraction between the first magnet 40 and the contact surface 51, contact C is ensured between the moving part of the guide device (outer sleeve 84 in the embodiments shown in Figures 1 to 4) and a part of the contact surface 51, as shown in Figure 4.

[0090] In one embodiment, the adhesive force is sized to ensure this contact C under the extreme conditions (maximum load and acceleration) required for the application of the system according to the present invention. The adhesive force particularly depends on the magnetization force of the first magnet 40, the distance d, the material of the plate 51, and so on.

[0091] As a non-limiting example, if the holding force of a cylindrical first magnet 40 made of neodymium N45 with a diameter of 4 mm and a height of 2 mm is 4.1 N, then the adhesive force of a pure iron plate 50 with a distance d of 0.3 mm is 2.1 N. The value obtained by multiplying this force by the distance of the screw 20 from the X axis must be greater than the torque transmitted under extreme operating conditions (maximum load and acceleration) of the system according to the present invention.

[0092] In one embodiment, the contact surface 51 of the ferromagnetic material has a dimension parallel to the translational direction of the nut 10 (i.e., parallel to the X-axis) of less than 15 μm, preferably less than 10 μm, for example, 1 μm.

[0093] In one embodiment, the contact surface of the ferromagnetic material has a roughness (Ra) of less than 1 μm, preferably less than 0.8 μm, for example, 0.2 μm. In one embodiment, hardening and / or grinding may be used to achieve this roughness.

[0094] In the embodiments shown in Figures 1 to 4, the plate 50 includes not only a contact surface 51 made of a ferromagnetic material, but also a fixing surface 52 (visible in Figure 4, for example) that fixes the plate 50 to the fixing casing 60.

[0095] In one embodiment, the entire plate 50 is made of a ferromagnetic material.

[0096] In one embodiment, for example, as shown in Figure 4, the contact surface 51 is substantially perpendicular to the fixed surface 52. If this perpendicularity is absent, the system according to the present invention can be calibrated before use.

[0097] Figure 5 shows the bottom view of another linear actuator 1 equipped with a screw nut transmission system according to another embodiment of the present invention. Figure 6 shows a side view of the linear actuator 1 shown in Figure 5. Figure 7 shows a longitudinal cross-section of the linear actuator 1 shown in Figure 6. Figure 8 shows a cross-section of the linear actuator in Figure 7 along axis AA.

[0098] In the embodiments shown in Figures 5 to 8, the screw-nut transmission system comprises a screw 20 that rotates around its principal axis X (visible, for example, in Figure 7) and a rotational speed provided by a motor M (which may be reduced by a reduction gear R). This rotation causes the nut 10 to translate along the X axis. In the embodiments shown in Figures 5 to 8, a ball is positioned between the screw 20 and the nut 10. This is similar to the system shown in Figures 1 to 4, except that in the embodiments shown in Figures 5 to 8, the first magnet 40 does not rotate.

[0099] In the designs shown in Figures 5 to 8, the screw 20 rotates within the cavity of the intermediate section 70, which functions as the rolling surface for the ball sleeves 61 and 62 that capture radial forces and bending moments.

[0100] Similar to Figures 1 to 4, the transmission system shown in Figures 5 to 8 includes a fixed casing 60 that surrounds the nut 10 and the screw 20.

[0101] In the embodiments shown in Figures 5 to 8, the transmission system is substantially perpendicular to the screw 20 and comprises a rod 30 (e.g., a pin or stud), the rod being integral with the nut 10 and therefore translating along the X-axis even within the groove 90. In the embodiments shown in Figures 5 to 8, this pin 30 is inserted into a cavity in the intermediate portion 70 connected to the screw 20.

[0102] In the designs shown in Figures 5 to 8, this rod 30 also supports the first magnet 40 and the guide device, which in this case is a ball bearing 80.

[0103] The guide device is used to guide the movement of the nut 10 (and the rod 30 in the embodiments shown in Figures 5 to 8) within the groove 90.

[0104] In the embodiments shown in Figures 5 to 8, the bearing 80 is also a deep groove ball bearing.

[0105] As can be seen in Figure 8, the ball bearing 80 is connected to the outer ring 83 and includes an (outer) sleeve 84 that rotates around the Y axis.

[0106] However, in the embodiments shown in Figures 5 to 8, the first magnet 40 is supported by the rod 30 but is not connected to the dynamic part of the bearing. Therefore, in this embodiment, the first magnet 40 does not rotate.

[0107] The present invention comprises a contact surface 51 made of a ferromagnetic material (exemplary and not limited to iron, an iron alloy, or a magnetizable steel) connected to a fixed casing 60. In the embodiments shown in Figures 5 to 8, this contact surface 51 belongs to a plate 50 connected to the fixed casing 60, for example, via one or more screws V.

[0108] According to the present invention, the contact surface 51 works in cooperation with the first magnet 40 to prevent the nut 10 from rotating.

[0109] In the embodiments shown in Figures 5 to 8, contact between the portion of the nut 10 moving within the groove 90 and one side of the groove is made indirectly, i.e., via one or both of the rod 30 and the guide device 80.

[0110] In one embodiment, for example as shown in Figure 8, at least one dynamic part of the guide device (an outer sleeve 84 in the embodiments shown in Figures 1 to 4) is in direct contact C with a part of the contact surface 51.

[0111] In one embodiment, for example, as shown in Figure 8, there is a distance d (air gap) between the first magnet 40 and the contact surface 51.

[0112] The magnetic attraction between the first magnet 40 and the contact surface 51 ensures contact C between the dynamic part of the guide device (outer sleeve 84 in the embodiments shown in Figures 1 to 4) and a part of the contact surface 51.

[0113] Similar to Figures 1 to 4, the gripping force is sized to ensure this contact C under the extreme conditions (maximum load and maximum acceleration) required for the application of the system according to the present invention.

[0114] Of course, the presence of the non-rotating first magnet 40 is not linked to the presence of the translating nut 10. The first magnet can be positioned on the translating element or on the casing, whether or not it rotates. Generally, the objective is to minimize the mass of the moving element. In several embodiments shown in Figures 1 to 4, Figures 5 to 8, and Figure 11, the first magnet is positioned on the moving part (a nut subassembly in Figures 1 to 4 and Figures 5 to 8, and a screw subassembly in Figure 11).

[0115] In the embodiments shown in Figures 9 to 11, the guide device is a sliding bearing 80'. In the embodiments shown in Figures 9 to 10, the object that moves is a nut, but in the embodiment shown in Figure 11, the object that moves is a screw. A linear actuator configuration 1 equipped with a rotating nut (as shown in Figure 11) is generally called a "non-captive (type) screw actuator".

[0116] In the embodiments shown in Figures 9 and 10, the nut 10, which translates along the main axis X (for example, shown in Figure 9), is integrated with an intermediate portion 70 that defines a cavity for receiving at least a portion of the rotating screw 20.

[0117] In the embodiments shown in Figures 9 to 10, the transmission system includes a fixed casing 60 that surrounds the nut 10 and the screw 20.

[0118] The fixed casing 60 further comprises a sliding bearing 80'. This sliding bearing 80' has grooves 90 defined on both sides. A portion of the intermediate piece 70 (or, if there is no intermediate piece 70, a portion of the nut 10) is positioned to translate along the axis X along the groove 90.

[0119] In the embodiments shown in Figures 9 to 10, the transmission system comprises a rod 30 (e.g., a pin or stud) that is substantially perpendicular to the intermediate section 70, integral with the intermediate section 70, and therefore integral with the nut 10, and thus moves along the groove 90 in translational motion along the X-axis. In the embodiments shown in Figures 9 to 10, the rod 30 is inserted into the cavity of the intermediate section 70.

[0120] As shown in Figures 9 to 10, this rod 30 supports the first magnet 40.

[0121] In the embodiments shown in Figures 9 to 10, the guide device guides the movement of the rod 30 within the groove 90. In particular, at least a portion of the rod 30 is in frictional contact with one side of the groove 90.

[0122] In the embodiments shown in Figures 9 to 10, the screw nut transmission system includes a first magnet 40 connected via a rod 30 to an intermediate portion 70 that moves within a groove 90. In this embodiment, the first magnet 40 does not rotate.

[0123] The transmission system according to the present invention comprises a contact surface 51 made of a ferromagnetic material connected to a fixed casing 60. Similar to the embodiments in Figures 1 to 8, in the embodiments in Figures 9 to 10, this contact surface 51 belongs to a plate 50 connected to the fixed casing 60 by, for example, one or more screws V. In another embodiment (not shown), this contact surface 51 is directly located on the fixed casing 60. In another embodiment, the plate 50 and the fixed casing 60 form an integral part.

[0124] According to the present invention, the contact surface 51 cooperates with the first magnet 40 to ensure contact between the rod 30 and one side of the groove, thereby preventing the rotation of the nut 10.

[0125] In one embodiment, there is a distance d (air gap) between the first magnet 40 and the contact surface 51, for example, as shown in Figure 10.

[0126] Due to the magnetic attraction between the first magnet 40 and the contact surface 51, contact C' is ensured between a portion of the sliding bearing 80' and a portion of the rod 30, as shown in Figure 10.

[0127] Similar to Figures 1 to 8, the adhesive force is sized to ensure this contact C' under the extreme conditions (maximum load and maximum acceleration) required for the application of the system according to the present invention. The adhesive force particularly depends on the magnetization force of the first magnet 40, the distance d, the material of the plate 51, and so on.

[0128] Figure 11 shows a longitudinal section of a perspective view of another linear actuator equipped with a screw-nut transmission system according to another embodiment of the present invention.

[0129] In the embodiment shown in Figure 11, the screw-nut transmission system includes a nut 10 that rotates about a principal axis X at a speed given by a motor M (visible, for example, in Figure 9). The screw 20 translates along this axis X.

[0130] In the embodiment shown in Figure 11, the screw 20 is integral with the intermediate portion 70, which defines a cavity that receives at least a portion of the screw 20.

[0131] In the embodiment shown in Figure 11, the transmission system includes a fixed casing 60 that surrounds the nut 10 and the screw 20.

[0132] The casing 60 includes a sliding bearing 80' having a groove 90 defined by its side. A portion of the intermediate piece 70 (or, if the intermediate piece 70 is absent, a portion of the screw 20) is positioned to translate along the X-axis along this groove 90.

[0133] In the embodiment shown in Figure 11, the transmission system includes a rod 30, similar to the embodiments shown in Figures 9 and 10. In the embodiment shown in Figure 11, this rod 30 supports the first magnet 40.

[0134] In the embodiment shown in Figure 11, the guide device guides the movement of the rod 30 within the groove 90. In particular, at least a portion of the rod 30 is in frictional contact with one side of the groove 90.

[0135] In the embodiment shown in Figure 11, the screw nut transmission system includes a first magnet 40 connected to a portion of an intermediate section 70 that moves within a groove 90 via a rod 30. In this embodiment, the first magnet 40 does not rotate.

[0136] In the present invention, the transmission system comprises a contact surface 51 made of a ferromagnetic material (exemplary and not limited to, iron, an iron alloy, or magnetizable steel) connected to a fixed casing 60. Similar to the embodiments in Figures 1 to 10, this contact surface 51 belongs to a plate 50 connected to the fixed casing 60, for example, via one or more screws V. In another embodiment (not shown), this contact surface 51 is directly attached to the fixed casing 60. In another embodiment, the plate 50 and the fixed casing 60 form a single integrated component.

[0137] In this invention, the contact surface 51 works in cooperation with the first magnet 40 to prevent the rotation of the screw 20.

[0138] In one embodiment, there is a distance d (air gap) between the first magnet 40 and the contact surface 51. Due to the magnetic attraction between the first magnet 40 and the contact surface 51, a portion of the sliding bearing 80' (in this case, one side of the groove 90) and a portion of the rod 30 come into direct contact.

[0139] In this case as well, the adhesive force is sized to ensure this contact even under the extreme conditions (maximum load and acceleration) required for the application of the system according to the present invention. The adhesive force particularly depends on the magnetization force of the first magnet 40, the distance d, the material of the plate 51, and so on.

[0140] The present invention relates to a rotary stroke bearing device, and this rotary stroke bearing device is - The transmission system according to the present invention, - A component (e.g., a lens) connected to the first element and thus arranged to move with translational motion, - To prevent the rotation of the first element, and thus prevent the rotation of the part, a contact surface made of a ferromagnetic material cooperates with the first magnet. It is equipped with.

[0141] In one embodiment, the lens moves linearly but does not rotate (as this may cause changes in the optical parameters of the lens configuration). In this case, the magnetic gap adjustment according to the present invention can be applied to this point. [Explanation of Symbols]

[0142] 1 Linear Actuator 10 nuts 20 screws 30 rods 40 First Magnet 50 boards 51 Contact surfaces 52 Fixed surface 60 Fixed casing 61 Inside the fixed casing 62. A piece that captures radial forces. 70 Intermediate piece 80 Ball bearings 80' Plain bearing 81 Rolling element 82 Inner Ring 83 Outer ring 84 Ball bearing sleeve 90 grooves AA Transverse axis C The point where the bearing and the contact surface make contact. C' The point where the bearing and the rod make contact. d Distance between the first magnet and the contact surface M Motor MR reducer T Head V-screw X thread axis Rotation axis of Y-bearing 80

Claims

1. - The first element (10 or 20), - A second element (20 or 10) arranged to rotate about an axis (X), wherein the second element (20 or 10) cooperates with the first element (10 or 20) so that when the second element (20 or 10) rotates, the first element (10 or 20) moves such that it performs translational motion along this axis (X), and A screw nut transmission system comprising, If the first element (10 or 20) is a nut, then the second element (20 or 10) is a screw, and if the first element is a screw, then the second element is a nut. The screw nut transmission system, - A fixed casing (60) is provided, which at least partially encloses the first element (10 or 20) and the second element (20 or 10) and has a groove (90) defined by a plurality of sides, - A portion comprising the first element (10 or 20) arranged to perform translational motion within the groove (90), In the screw nut transmission system, the screw nut transmission system is - This part and the fixed casing (60) are each connected to a first magnet (40), - One or both of the contact surface and the second magnet are made of a ferromagnetic material. The contact surface and the second magnet, or one or both, are connected to the fixing casing and the first part, respectively. The contact surface and the second magnet, or one or both, cooperate with the first magnet (40) to prevent the rotation of the first element (10 or 20). The contact surface (51) and one or both of the second magnet are provided. A screw nut transmission system characterized by the following.

2. The system according to claim 1, further comprising a guide device (80, 80') for guiding the displacement of the one portion of the first element (10 or 20).

3. The system according to claim 1 or 2, wherein the guide device is a rolling element guide device (80) having a plurality of rolling elements (80).

4. The system according to claim 3, wherein the rolling element guide device (80) is a ball bearing.

5. The rolling element guide device (80) The outer ring (83) comprises an outer ring (83) in which at least a portion is arranged to roll on one or both of the contact surface (51) and the second magnet, which are made of a ferromagnetic material, or The aforementioned rolling element guide device, The system according to claim 3 or 4, wherein the outer ring (83) is connected to a sleeve, and at least a portion of the sleeve is arranged to roll on a contact surface (51) made of a ferromagnetic material and on one or both of the second magnets.

6. The system according to claim 5, wherein the first magnet (40) is connected to the sleeve (84) or the outer ring (83).

7. The system according to any one of claims 3 to 6, wherein the rolling element is a non-magnetic material.

8. The system according to any one of claims 1 to 7, wherein the portion of the first element (10 or 20) is connected to a rod (30) which moves within the groove and carries the first magnet (40).

9. The system according to claim 8, wherein the rolling element guide device (80) is carried by the rod (30).

10. The system according to claim 1 or 2, wherein the guide device is a sliding bearing (80'), and the sliding bearing (80') includes the groove (90).

11. The system according to any one of claims 1 to 10, wherein the dimension of the contact surface (51) on one or both of the ferromagnetic material and the second magnet, parallel to the translational direction (X) of the first element, is less than 15 μm.

12. The system according to any one of claims 1 to 11, wherein the roughness (Ra) of the contact surface on one or both of the ferromagnetic material and the second magnet is less than 1 μm.

13. The aforementioned fixed casing (60) A plate (50), wherein the plate (50) comprises the contact surface (51) made of a ferromagnetic material and one or both of the second magnet, Mounting surface (52) for fixing the plate (50) to the fixing casing (60) The system according to any one of claims 1 to 12, comprising:

14. The system according to claim 13, wherein the substrate (50) is made of a ferromagnetic material.

15. The system according to claim 13 or 14, wherein one or both of the contact surface (51) and the second magnet are perpendicular to the mounting surface (52).

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