DOUBLE CARDAN MECHANICAL LINKAGE DEVICE
The monobloc double-cardan mechanical linkage device with a single-piece design and elastic deformation capabilities addresses precision and bulkiness issues in optical and optronic instruments, enhancing alignment and accuracy.
Patent Information
- Application Number
- FR2023011935
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-11-02
- Publication Date
- 2025-11-28
- Estimated Expiration
- 2043-11-02
AI Technical Summary
Existing double-cardan mechanical linkage devices in optical and optronic instruments suffer from precision defects due to manufacturing and assembly tolerances, leading to misalignment and axial inaccuracy, and are often too bulky for precise applications.
A monobloc double-cardan mechanical linkage device with a single-piece design featuring a double universal joint, comprising end blocks and intermediate films that allow for elastic deformation to absorb misalignment and axial forces, ensuring precise adjustment and flexibility.
The device effectively compensates for misalignment and axial forces, providing precise adjustment and flexibility while transmitting torque, thus improving the accuracy and compatibility of optical and optronic instruments.
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Abstract
Description
Title of the invention: MECHANICAL JOINT DEVICE WITH DOUBLE CARDAN Technical field of the invention
[0001] The present invention relates to a double gimbal mechanical linkage device, and an optical or optronic instrument comprising such a device. Technical background
[0002] An optical or optronic instrument may include moving parts and a motor for setting these moving parts in motion. This is, for example, the case of a lens which can be moved in translation along an axis by means of a motor and a linkage mechanism transforming a rotation of the motor's output shaft into a translational movement of the lens.
[0003] In a camera, for example, to ensure its observational accuracy, all the components of the zoom system must be positioned very precisely. Some of these mechanical components, due to insufficient precision in the physical measuring instruments, cannot meet the positioning specifications of the optical design. This results, in this case, in axial misalignment in the transmission, and thus inaccuracy of the system.
[0004] In this type of instrument, it is therefore useful to use a double cardan device to ensure the mechanical connection of a drive shaft, in order to compensate for misalignments and axial forces while transmitting a rotational torque.
[0005] In current technology, double-cardan mechanical linkage devices are unsatisfactory. In particular, they do not allow for optimal precision, especially in adjusting the displacements of moving parts. Furthermore, they are generally formed by assembling several parts, which introduces precision defects due to manufacturing and assembly tolerances. In addition, known linkage devices are generally too bulky and therefore incompatible with the intended application.
[0006] A connecting device must allow for precise adjustment, even when it undergoes misalignment, and must retain a certain degree of flexibility for this adjustment. A connecting device that is too rigid would risk breaking and would therefore be too fragile.
[0007] There is therefore a need for a double cardan mechanical linkage device which makes it possible to solve at least some of the problems and disadvantages mentioned above. Summary of the invention
[0008] The present invention proposes a double-cardan mechanical linkage device, this device having a generally elongated shape along an axis of elongation and comprising:
[0009] - a first longitudinal end of a mechanical connection,
[0010] - a second longitudinal end of mechanical connection, and
[0011] - a double universal joint between the first and second longitudinal ends,
[0012] characterized in that the first and second ends are formed of a single piece with the double universal joint so that the connecting device is a single unit, and in that the double universal joint comprises:
[0013] - a first end block which is rigidly connected to the first longitudinal end student,
[0014] - a second end block which is rigidly connected to the second longitudinal end student,
[0015] - a first intermediate block which is connected to the first end block by a first intermediate film of matter,
[0016] - a second intermediate block which is connected to the second end block by a second intermediate film of material, the first and second intermediate blocks being arranged between the first and second end blocks, the first and second intermediate films being located in a first plane of symmetry of the double gimbal which passes through the axis of elongation, and
[0017] - a central block which is located between the first and second intermediate blocks and which is connected to these first and second intermediate blocks respectively by first and second central films of matter, these first and second central films being located in a second plane of symmetry of the double gimbal which passes through the axis of elongation and which is perpendicular to the first plane of symmetry.
[0018] The device according to the invention makes it possible to absorb the misalignment and positional defects of the transmission between two elements while transmitting a force such as a torque and ensuring axial damping.
[0019] The term "double cardan joint" refers to the fact that the device can be replaced by a system of two cardan joints placed one after the other. A cardan joint allows the transmission of angular rotation between two elements, such as two shafts, whose geometric axes intersect. A double cardan joint therefore ensures angular rotation of two parallel axes that are not necessarily aligned. The term "monobloc" refers to the fact that the system is composed of only one piece. The films are thin walls that allow the device to twist along different axes. The films thus ensure that the monobloc device performs its double cardan joint function. The different blocks prevent plastic deformation of the geometry.
[0020] The geometric shapes are defined so as to meet the mechanical strength requirements both statically and dynamically.
[0021] The device according to the invention may comprise one or more of the following features, taken individually or in combination with each other: the device includes a third plane of symmetry of the double gimbal, which is perpendicular to the axis of extension and which passes between the first and second intermediate blocks and in the middle of the central block; the first and second end blocks have identical shapes and dimensions, and / or the first and second intermediate blocks have identical shapes and dimensions; the first and second end blocks have in section in said second plane a general triangular shape of which one base is connected to one of the longitudinal ends, and one vertex is connected to one of the intermediate films; the first and second intermediate blocks each have a general shape of a disk or cylinder centered on the axis of elongation; Each of the end blocks is separated from the nearest intermediate block by a distance measured along the elongation axis, which is less than or equal to 1 mm, and which is the smallest on the side of the longitudinal end to which the end block is connected; the intermediate blocks are separated from each other by a distance measured along the elongation axis, which is less than or equal to 1 mm. the measured distance is the smallest at one of the faces of the disk or cylinder, or at the faces of the disk or cylinder; the distance between the intermediate blocks is less than a measured distance along the elongation axis between the central block and each of the intermediate blocks; the first and second intermediate blocks each have a first recess in which one of the end blocks is engaged at least partially, and a second recess in which the said central block is engaged at least partially; the first and second indentations are located on two opposite faces of the disk or cylinder; the material films are each connected to the bottom of one of the recesses, by two connecting fillets which are located respectively on either side of the material film, each of these connecting fillets extending over the entire length of the material film and having a concave curved shape in the form of a portion of a cylinder which extends angularly over at least 180° around an axis parallel to the material film; the central block has a generally elongated shape along a perpendicular axis in the foreground of symmetry;
[0022] — the central block has in section in said first plane of symmetry a general shape oval or elliptical;
[0023] — the films are elastically deformable, in particular in bending;
[0024] — the films have a thickness less than or equal to 1 mm, preferably less than or equal to 0.5mm, and more preferably less than or equal to 0.2mm;
[0025] — the device has a total length measured along the elongation axis, which is between 20 and 100mm, and preferably between 30 and 50mm;
[0026] — the double cardan joint has a total length measured along the elongation axis, which is between 5 and 50mm, and preferably between 10 and 30mm;
[0027] — the central block is located between two identical pockets formed in the double cardan, each of these pockets separating the central block from one of the intermediate blocks;
[0028] — the volume (of vacuum) of each of the pockets is greater than or equal to the volume (of material) of the central block.
[0029] The invention further relates to an optical or optronic instrument comprising a motor, a movable optical equipment, and a device as described above, the motor comprising a shaft which is coupled to one of the longitudinal ends of the device, the other longitudinal end of which is connected to the optical or optronic equipment for the purpose of moving it. Brief description of the figures
[0030] Other features and advantages will become apparent from the following description of a non-limiting embodiment of the invention with reference to the accompanying drawings in which:
[0031] [Fig-1] [Fig.1] is a schematic perspective view of a linking device double cardan mechanical joint, according to a first embodiment of the invention,
[0032] [Fig.2] [Fig.2] is another schematic perspective view of the device of [Fig.1],
[0033] [Fig.3] [Fig.3] is a schematic cross-sectional view along line III-III of the device of [Fig.1],
[0034] [Fig.4] [Fig.4] is a schematic cross-sectional view along line IV-IV of the device of [Fig.2],
[0035] [Fig.5] [Fig.5] is a schematic perspective view of a double-cardan mechanical linkage device, according to a second embodiment of the invention,
[0036] [Fig.6] [Fig.6] is another schematic perspective view of the device of [Fig.5],
[0037] [Fig.7] [Fig.7] is a schematic perspective view of the device in [Fig.5] and shows a deformation of the device due to a misalignment of its longitudinal ends. students,
[0038] [Fig.8] [Fig.8] is a schematic perspective view of the device of [Fig.5] and shows a deformation of the device due to axial compression,
[0039] [Fig.9] [Fig.9] is another schematic perspective view of the device of [Fig.5] and shows the deformation of the device due to axial compression,
[0040] [Fig. 10] [Fig. 10] is a schematic perspective view of the device of [Fig. 5] and shows a deformation of the device due to axial tension,
[0041] [Fig. 11] [Fig. 11] is another schematic perspective view of the device in [Fig. 5] and shows the deformation of the device due to axial tension, and
[0042] [Fig. 12] [Fig. 12] is a schematic perspective and cross-sectional view of an optical or optronic instrument comprising a device according to the invention. Detailed description of the invention
[0043] Figures 1 to 4 illustrate a first embodiment of a double cardan mechanical linkage device 10.
[0044] This device 10 is particularly suitable, but not exclusively, for use in an optical or optronic instrument such as that illustrated in [Fig. 12].
[0045] The device 10 has a general elongated shape along an elongation axis which is denoted X. For example, it has a total length measured along the X axis, which is between 20 and 100 mm, and preferably between 30 and 50 mm.
[0046] Essentially, the device 10 comprises three parts, namely:
[0047] - a first longitudinal end 12 of mechanical connection, that is to say, suitable for to be mechanically connected to an element,
[0048] - a second longitudinal end 14 of mechanical connection, that is to say, capable of be mechanically connected to another element, and
[0049] - a double cardan joint 16 between the first and second longitudinal ends 12 and 14.
[0050] In the example shown, the ends 12, 14 have different lengths along the X axis.
[0051] The ends 12, 14 may be of the same type or of different types. In the example shown, they are of the same type.
[0052] Each of the ends 12, 14 may have a generally tubular shape that is threaded and further includes axial slots 18 to define angular sections that are elastically deformable in the radial direction. To connect one of these ends 12, 14 to an element, it is sufficient to insert a finger of this element into the tubular end and then screw a nut previously mounted on the finger onto the thread of this tubular end. This screwing causes the elastic deformation of the angular sections and their radial clamping onto the finger of the element.
[0053] Each of the ends 12, 14 preferably has an external diameter smaller than the external diameter of the double universal joint 16. Each of the ends 12, 14, for example, has an external diameter less than or equal to 10 mm, preferably less than or equal to 7 mm, and more preferably less than or equal to 5 mm. The double universal joint 16, for example, has an external diameter between 10 and 30 mm, preferably between 10 and 20 mm, and more preferably between 10 and 15 mm.
[0054] One of the first features of the linkage device 10 according to the invention is related to the fact that the ends 12, 14 are formed in one piece with the double cardan 16 so that the linkage device 10 is monobloc.
[0055] This connecting device 10 is, for example, made of a metal alloy, and for example of maraging steel. Due to its relatively complex shape, it can be manufactured by wire electrical discharge machining (EDM) or by additive manufacturing.
[0056] Another of the features of device 10 relates to the composition of its double cardan 16.
[0057] The double universal joint 16 comprises:
[0058] - a first end block 20 which is rigidly connected to the first end lon gitudinale 12,
[0059] - a second end block 22 which is rigidly connected to the second longitudinal end study 14,
[0060] - a first intermediate block 24 which is connected to the first end block 20 by a first intermediate film of material 26,
[0061] - a second intermediate block 28 which is connected to the second end block 22 by a second intermediate film of material 30, and
[0062] - a central block 32 which is located between the first and second intermediate blocks 24, 28 and which is connected to these first and second intermediate blocks 24, 28 respectively by first and second central films of matter 33, 34.
[0063] The double cardan 16 has for example a total length measured along the X axis, which is between 5 and 50mm, and preferably between 10 and 30mm.
[0064] The first and second intermediate blocks 24, 28 are arranged between the first and second end blocks 20, 22.
[0065] The first and second intermediate films 26, 30 are located in a first plane PI of the double gimbal 16 which passes through the extension axis X.
[0066] The first and second central films 33, 34 are located in a second plane P2 of symmetry of the double gimbal 16 which passes through the elongation axis X and which is perpendicular to the first plane of symmetry PL
[0067] Advantageously, the films 26, 30, 33, 34 are elastically deformable, particularly in bending and / or compression and / or tension. These films preferably have a thickness less than or equal to 1 mm, more preferably less than or equal to 0.5mm, and even more preferably less than or equal to 0.2mm.
[0068] In the example shown, the device 10 includes a third plane P3 of symmetry of the double cardan 16, which is perpendicular to the elongation axis X and which passes between the first and second intermediate blocks 24, 28 and in the middle of the central block 32.
[0069] As in the example shown, the first and second end blocks 20, 22 may have identical shapes and dimensions, and / or the first and second intermediate blocks 24, 28 may have identical shapes and dimensions.
[0070] The first and second end blocks 20, 22 can have in section in the second plane P2 a general triangular shape of which a base B is connected to one of the longitudinal ends 12, 14, and a vertex S is connected to one of the intermediate films 26, 30.
[0071] The first and second intermediate blocks 24, 28 can each have a general shape of disk or cylinder centered on the elongation axis X.
[0072] Each of the end blocks 20, 22 can be separated from the nearest intermediate block 24, 28 by a distance L1 measured along the elongation axis X.
[0073] This distance L1 is preferably less than or equal to 1 mm, preferably less than or equal to 0.5 mm, and more preferably less than or equal to 0.3 mm. This distance L1 may be the smallest on the side of the longitudinal end 12, 14 to which the end block 20, 22 is connected.
[0074] The intermediate blocks 24, 28 are separated from each other by a distance L2 measured along the elongation axis X, which is less than or equal to 1mm, preferably less than or equal to 0.7mm, and more preferably less than or equal to 0.5mm.
[0075] Preferably, the measured distance L1 is lowest at one of the faces of the aforementioned disk or cylinder, namely at the face located on the side of the end block 20, 22 in the example shown.
[0076] Preferably, the measured distance L2 is the smallest at the faces of the aforementioned disk or cylinder, namely at the faces located on the sides of the central block 32.
[0077] This distance L2 is preferably less than a distance L3 measured along the same axis X between the central block 32 and each of the intermediate blocks 24, 28.
[0078] The first and second intermediate blocks 24, 28 can each have a first recess 40 in which one of the end blocks 20, 22 is engaged at least partially, and a second recess 42 in which the central block 32 is engaged at least partially.
[0079] Preferably, these first and second recesses 40, 42 are located on two opposite faces of the aforementioned disk or cylinder.
[0080] The material films 26, 30, 33, 34 are preferably each connected to the bottom of one recesses 40, 42, by two connecting fillets 44, 46.
[0081] These fillets 44, 46 are located respectively on either side of the material film 26, 30, 33, 34. Each of these fillets 44, 46 can extend over the entire length of the material film 26, 30, 33, 34 and preferably has a concave curved shape in the form of a portion of a cylinder which extends angularly over at least 180° around an axis Y parallel to the material film 26, 30, 33, 34.
[0082] The radius of curvature of each of the fillets 44, 46, around its axis Y, is preferably less than or equal to 1mm, and more preferably less than or equal to 0.6mm.
[0083] The central block 32 can have a general elongated shape along an axis Z perpendicular to the first plane of symmetry PI, as in the example shown.
[0084] The central block 32 may have in section in the first plane of symmetry PI a general oval or elliptical shape.
[0085] The symmetries guarantee rotation without causing imbalance (in rotation) and / or axial fragility.
[0086] The central block 32 is located between two identical pockets 48 formed in the double cardan 16, each of these pockets 48 separating the central block 32 from the two intermediate blocks 24, 28.
[0087] The volume (of void) of each of the pockets 48 is here very small compared to the volume (of material) of the central block 32.
[0088] Figures 5 and 6 show a variant embodiment of the device 10 which differs from the previous embodiment by the shape of the intermediate blocks 24, 28. Compared to the previous embodiment, the intermediate blocks 24, 28 are more hollowed out or cut out to reduce their mass.
[0089] In this variant, the volume (of void) of each of the pockets 48 is greater than or equal to the volume (of material) of the central block 32. This allows the axial stiffness of the device 10 to be varied without affecting its radial stiffness. It is thus possible to optimize the stiffness of the device 10 by adjusting the volume of the pockets 48.
[0090] Figures 7 to 11 show the elastic deformation capacities of device 10 which relate to device 10 of figures 1 to 4, as well as that of figures 5 and 6.
[0091] In [Fig. 7], the device 10 undergoes misalignment, meaning that the ends 12, 14 of the device are no longer aligned on the same axis, namely the elongation axis X. On the contrary, the ends 12, 14 are aligned respectively on two parallel axes XI, X2. This phenomenon causes an elastic deformation of the double gimbal 16, which is permitted by an elastic deformation of the films 26, 30 and / or the films 33, 34, and which results in a tilting of at least some blocks relative to the ends 12, 14.
[0092] In figures 8 and 9, the device 10 is subjected to an axial compressive force, This means that the ends 12, 14 of the device are brought axially closer together. This phenomenon causes an elastic deformation of the double gimbal 16, which is permitted by an elastic deformation of the films 26, 30 and / or the films 33, 34. This results, on the one hand, in the end blocks 20, 22 coming closer to the intermediate blocks 24, 28, and possibly in axial contact of the end blocks 20, 22 with the intermediate blocks 24, 28 (contacts C1), and / or in the intermediate blocks 24, 28 coming closer to each other, and possibly in axial contact of these intermediate blocks 24, 28 with each other (contacts C2). These contacts occur on the aforementioned faces.
[0093] In Figures 10 and 11, the device 10 is subjected to an axial tensile force, meaning that the ends 12, 14 of the device 10 are axially separated from each other. This phenomenon causes an elastic deformation of the double gimbal 16, which is permitted by an elastic deformation of the films 26, 30 and / or the films 33, 34. This results, on the one hand, in a separation of the end blocks 20, 22 relative to the intermediate blocks 24, 28, and / or a separation of the intermediate blocks 24, 28 from each other. The aforementioned distances L1 and L2 then increase.
[0094] The present invention also relates to an optical or optronic instrument 50 such as that illustrated in [Fig. 12].
[0095] This instrument 50 comprises a motor 52, a movable optical equipment 54, and a device 10 as described above.
[0096] The motor 52 here includes a shaft 56 which is coupled to one of the longitudinal ends 12 of the device 10.
[0097] The other longitudinal end 14 of the device 10 is connected to the optical or optronic equipment 54 for the purpose of its movement.
[0098] In the example shown, the optical equipment 54 is a lens carried by a support 58, which is connected by a barrel 62 to a worm gear 60 coupled to the other longitudinal end 14 of the device 10. The rotational torque of the shaft 56 is transmitted by the device 10 to the worm gear 60, which is driven in rotation and passes through the barrel 62. The barrel 62, for example a ball bearing, transforms the rotation of the worm gear 60 into axial translation. The barrel 62 moves along the worm gear 60 and transmits this movement to the lens via its support 58.
[0099] Although the invention has been described in the context of an optical or optronic application, the double gimbal mechanical linkage device 10 could be used in another context or field, in particular for any application comprising an element in axial motion (translation) produced by a radial motion (motor).
Claims
Demands
1. A double-cardan mechanical linkage device (10), said device (10) having a generally elongated shape along an elongation axis (X) and comprising: - a first longitudinal end (12) of the mechanical linkage, - a second longitudinal end (14) of the mechanical linkage, and - a double cardan joint (16) between the first and second longitudinal ends (12, 14), characterized in that the first and second ends (12, 14) are formed in one piece with the double cardan joint (16) so that the linkage device (10) is monobloc, and in that the double cardan joint (16) comprises: - a first end block (20) which is rigidly connected to the first longitudinal end (12), - a second end block (22) which is rigidly connected to the second longitudinal end (14), - a first intermediate block (24) which is connected to the first end block (20) by a first film material intermediate (26),- a second intermediate block (28) which is connected to the second end block (22) by a second intermediate film of material (30), the first and second intermediate blocks (24, 28) being arranged between the first and second end blocks (20, 22), the first and second intermediate films (26, 30) being located in a first plane (PI) of symmetry of the double gimbal (16) which passes through the elongation axis (X), and - a central block (32) which is located between the first and second intermediate blocks (24, 28) and which is connected to these first and second intermediate blocks (24, 28) respectively by first and second central films of material (33, 34), these first and second central films (33, 34) being located in a second plane (P2) of symmetry of the double gimbal (16) which passes through the elongation axis (X) and which is perpendicular to the first plane of symmetry (PI).,
2. Device (10) according to claim 1, wherein it comprises a third plane (P3) of symmetry of the double cardan (16), which is perpendicular to the axis of elongation (X) and which passes between the first and second intermediate blocks (24, 28) and in the middle of the central block (32).
3. Device (10) according to claim 1 or 2, wherein the first and second end blocks (20, 22) have shapes and dimensions identical, and / or the first and second intermediate blocks (24, 28) have identical shapes and dimensions.
4. Device (10) according to any one of the preceding claims, wherein the first and second end blocks (20, 22) have in section in said second plane (P2) a general triangular shape of which a base (B) is connected to one of the longitudinal ends (20, 22), and a vertex (S) is connected to one of the intermediate films (26, 30).
5. Device (10) according to any one of the preceding claims, wherein the first and second intermediate blocks (24, 28) each have a general shape of a disc or cylinder centered on the elongation axis (X).
6. Device (10) according to any one of the preceding claims, wherein each of the end blocks (20, 22) is separated from the nearest intermediate block (24, 28) by a distance (Ll) measured along the elongation axis (X), which is less than or equal to 1mm, and which is the smallest on the side of the longitudinal end (12, 14) to which the end block (20, 22) is connected.
7. Device (10) according to any one of the preceding claims, wherein the intermediate blocks (24, 28) are separated from each other by a distance (L2) measured along the elongation axis (X), which is less than or equal to 1mm.
8. Device (10) according to claim 7, wherein the distance (L2) between the intermediate blocks (24, 28) is less than a distance (L3) measured along the elongation axis (X) between the central block (32) and each of the intermediate blocks (24, 28).
9. Device (10) according to any one of claims 6 to 8, depending on claim 5, wherein the measured distance (L1, L2) is lowest at one of the faces of the disk or cylinder, or at the faces of the disk or cylinder.
10. Device (10) according to any one of the preceding claims, wherein the first and second intermediate blocks (24, 28) each have a first recess (40) in which one of the end blocks (20, 22) is engaged at least partially, and a second recess (42) in which said central block (32) is engaged at least partially.
11. Device (10) according to claim 10, depending on one of claims 5 or 8, wherein the first and second recesses (40, 42) are located on two opposite faces of the disc or cylinder.
12. Device (10) according to claim 10 or 11, wherein the material films (26, 30, 33, 34) are each connected to the bottom of one of the recesses (40, 42), by two connecting fillets (44, 46) which are located respectively on either side of the material film (26, 30, 33, 34), each of these connecting fillets (44) extending over the entire length of the material film (26, 30, 33, 34) and having a concave curved shape in the form of a portion of a cylinder which extends angularly over at least 180° around an axis (Y) parallel to the material film (26, 30, 33, 34).
13. Device (10) according to any one of the preceding claims, wherein the central block (32) has a general elongated shape along an axis (X) perpendicular to the first plane of symmetry (PI).
14. Optical or optronic instrument (50) comprising a motor (52), movable optical equipment (54), and a device (10) according to any one of the preceding claims, the motor (52) comprising a shaft (56) which is coupled to one of the longitudinal ends (12) of the device (10) the other longitudinal end (14) of which is connected to the optical or optronic equipment (54) for the purpose of moving it.