Linear unit and system

Abstract

Linear unit (10) for converting a rotary motion into a translational motion, comprising the following: - a case (12), - a spindle (14) which is rotatably mounted in the housing (12), - a nut (16) that interacts with the spindle (14), and - two fastening arrangements (30) for attaching the housing (12) to an external structure (E), wherein the fastening arrangements (30) each comprise at least two pins (32) arranged transversely to the spindle (14), the pins (32) being movably mounted in bearing shells (34) arranged on opposite sides of the spindle (14).

Description

[0001] The present invention relates to a linear unit and a system comprising such a linear unit.

[0002] Linear units are used in engineering to move and position components, such as machine parts. These units convert rotary motion, for example from an electric motor, into translational motion. This is achieved using a rotatable spindle that interacts with a nut. As the spindle rotates with the motor, the nut moves translationally along the spindle. The movement of the nut is then transferred to the machine part, for example via a pushrod.

[0003] The longevity of such linear units depends heavily on the loads exerted on the spindle. In particular, the service life of the spindle and / or nut is significantly reduced by radial loads, which can increase friction or even slightly deform the spindle. Such loads can arise not only from inadequate (radial) guidance of the machine part but also from thermal expansion of components within the linear unit itself. Furthermore, if the linear unit is rigidly attached to an external structure, deformation of the structure can cause deformation of the linear unit, i.e., of its components, which can also lead to such loads.

[0004] From DE 10 2015 204 074 A1, a linear actuator is known which comprises a spindle drive and a drive unit. A bearing unit with a solid bearing block is arranged between the drive unit and the spindle drive. A pivot bearing is connected to the bearing block. A housing, which is tiltably mounted in a connecting structure, can be pivoted about an axis located between the drive unit and the spindle drive by means of bolts attached to the bearing block.

[0005] DE 10 2015 204 073 A1 discloses an actuator with a housing in which current-carrying and mechanical components and a spindle drive are arranged. The housing is tiltably mounted in a connecting structure. For this purpose, bearing journals are located on the housing, forming components of a sliding bearing.

[0006] One object of the invention is to increase the service life of a linear unit, in particular to reduce the loads acting on the linear unit due to deformation of an external structure to which the linear unit is attached or due to thermal expansion of the linear unit.

[0007] This problem is solved by a linear unit and a system comprising such a linear unit, according to the independent claims.

[0008] Preferred embodiments are the subject of the dependent claims and the following description.

[0009] The linear unit for converting rotary motion into translational motion according to a first aspect of the invention comprises i) a housing, ii) a spindle rotatably mounted in the housing, iii) a nut interacting with the spindle, and iv) two fastening assemblies for attaching the housing to an external structure. Each fastening assembly comprises at least two pins arranged transversely to the spindle, in particular to an axis of rotation of the spindle. The pins are preferably movably mounted in preferably annular bearing shells arranged on opposite sides of the spindle, in particular on opposite sides of the axis of rotation of the spindle.

[0010] One aspect of the invention is based on the approach of flexibly, and in particular by means of a hinge, attaching the linear unit to an external structure, so that a deformation of the external structure is not transmitted to the linear unit, in particular to the spindle and / or a housing in which the spindle is arranged. For this purpose, the linear unit preferably comprises a fastening system for attaching the linear unit to the external structure, which allows the linear unit, in particular the spindle and / or the housing, to maintain its original shape and / or orientation even if the external component deforms. The original shape preferably corresponds to the shape without any load. For example, the fastening system can be configured to self-align the linear unit if the fastening points at which the linear unit is attached to the external structure are displaced due to a deformation of the external structure.The linear unit, and in particular the mounting system, can thus compensate, at least in part, for any misalignments between the linear unit and the external structure caused by deformation of the external structure during operation. Furthermore, the linear unit, and in particular the mounting system, can compensate, at least in part, for any changes in the distance between mounting points on the linear unit caused by thermal expansion of the linear unit itself.

[0011] Preferably, the linear unit comprises two fastening arrangements for attaching the housing of the linear unit to the external structure, e.g., at four fastening points. The fastening arrangements are advantageously configured to hold the linear unit, in particular the nut and / or the housing, in an unloaded state, especially regardless of the position of the four fastening points relative to the linear unit. In other words, the four fastening points can move relative to the linear unit, at least to a certain extent that can be expected considering thermal expansion or deformation of the external structure due to external loads, without exerting any forces on the linear unit.

[0012] For example, the two mounting arrangements can each comprise two pins that are movably mounted in respective bearing shells. The bearing shells or pins can thus move with the external structure under deformation or with the linear unit under thermal expansion, without or with only partial transmission of this movement to the corresponding counterpart. In other words, by movably mounting the pins in the bearing shells, the pins and the bearing shells—and thus the linear unit and the external structure—are preferably movably decoupled, at least to some extent. Such a pin movably mounted in a bearing shell can, for example, be rotatably, pivotably, and / or translationally (i.e., linearly movable) mounted in the bearing shell. This means that the pin can rotate, pivot, and / or move translationally relative to the bearing shell.The journal can be received by a corresponding seat in the bearing shell. The seat can, for example, be rotatable and / or rotatably arranged within the bearing shell. Additionally or alternatively, the seat can allow translational (linear) movement of the journal relative to the bearing shell.

[0013] By equipping the linear unit with such a fastening system, in particular with two such fastening arrangements, the functionality and reliability of the linear unit can be ensured, even for long periods of time.

[0014] The nut and spindle preferably interact via several planetary rollers arranged radially between them. The nut and spindle can thus form a planetary roller screw drive. Alternatively, the nut and spindle can interact via several balls, thus forming a ball screw drive.

[0015] Preferred embodiments of the invention and further aspects thereof are described below, all of which can be combined with each other and with the aspects of the invention described below, unless this is expressly excluded.

[0016] The two mounting assemblies are preferably arranged at opposite ends of the linear unit, particularly the housing. Accordingly, the spindle, in particular an external thread of the spindle, is positioned axially between the two mounting assemblies such that the sum of the axial distances between the nut and each of the mounting assemblies is constant. This allows for a particularly stable and robust mounting of the linear unit to the external structure.

[0017] Here and in the following, unless explicitly stated otherwise, “axial” refers to a direction parallel to a longitudinal axis of the linear unit, i.e., parallel to the spindle or its axis of rotation.

[0018] To decouple the linear unit from any deformation of the external structure that affects the alignment of the mounting points—that is, the components of the mounting assemblies fixed to the external structure—the pins of at least one of the mounting assemblies are rotatably mounted in the respective bearing shells. For example, bending of the external structure in a plane perpendicular to the pins can affect the alignment of the mounting points. Therefore, it is preferred that the pins be rotatable about their longitudinal axes relative to the bearing shells.

[0019] To allow decoupling from bending of the external structure in a plane parallel to the pins, the pins of at least one of the mounting assemblies are preferably axially movable relative to their respective bearing shells. For this purpose, the pins may have axial play relative to their seat in the respective bearing shell. Here, "axial" refers to the longitudinal axis of the pins. Accordingly, the pins are advantageously positioned further in and / or out of their respective seats.

[0020] In another preferred embodiment, one of the mounting arrangements is located on a head of the linear unit, the head being attached to a front end plate of the housing. The front end plate can close the housing at its front, for example, in an area adjacent to a free end of the spindle. Attaching the head to the front end plate allows for additional degrees of freedom for moving the mounting arrangement on the head, in particular for adjusting its orientation and / or axial position.

[0021] For example, the head can be pivotally mounted to the front end plate of the housing and / or be axially movable relative to the front end plate of the housing. This allows the orientation and / or position of the corresponding mounting arrangement to be changed without affecting the orientation and / or position of the housing.

[0022] Such an adaptive connection between the front end plate and the head piece can be achieved by providing a head piece that includes a cylindrical bore in which an axial projection of the front end plate is received. In some embodiments, the projection has a lateral surface with an annular convex curvature. The projection can, for example, be formed by a cylindrical pin with a spherical front end. Advantageously, the curvature of the projection contacts an inner wall of the central bore and can slide axially along the inner wall and / or pivot with respect to the wall.

[0023] Alternatively, the axial projection can be cylindrical, i.e., have a completely flat lateral surface. In this case, the head piece preferably includes a cavity with an inner wall region that is complementary to a spherical surface region of a central bearing disk. Thus, the central bearing disk is pivotable within the cavity. The central bearing disk advantageously includes a central bore in which the axial cylindrical projection of the front end plate is axially movable. Therefore, the head piece and the central bearing disk can form a central spherical bearing that is axially movable about the axial cylindrical projection of the front end plate.

[0024] Preferably, the pins of at least one of the fastening assemblies have a mounting base for securely attaching the pins to the external structure. In this case, the bearing shells of one of the fastening assemblies are advantageously arranged in the head piece. The bearing shells are preferably formed, at least in part, by recesses in the head piece that receive the pins. Bushings can additionally be arranged in the recesses to allow rotation of the received pins relative to the head piece.

[0025] Alternatively, the pins of one of the mounting arrangements extend from the head piece to opposite sides. In this case, the pins are preferably integral with the head piece, i.e., formed in one piece with it. To improve the adaptability of the head piece's orientation to deformation of the external structure and / or thermal expansion of the linear unit, it is preferred that the pins be pivotably mounted in the bearing shells with respect to the bearing shell's central axis. In particular, the bearing shells can form spherical bearings for the pins.

[0026] The bearing shell center axis is preferably parallel to a surface normal of the bearing shell opening, i.e., an area enclosed by the bearing shell. If the bearing shells are attached to the external structure at a mounting surface, the bearing shell center axes are preferably perpendicular to the mounting surface.

[0027] Another option for providing at least one additional degree of freedom for aligning and / or positioning the pins of the fastening arrangement mounted on the headpiece with respect to the external structure and / or the housing is to provide a headpiece that includes a bearing eye in which a central spherical bearing is arranged. In some embodiments, this central spherical bearing can be formed by bushings with spherical contact surfaces.

[0028] Preferably, the journals extend from the central spherical bearing to both sides of the bearing eye. In this case, the journals on both sides of the head can be formed by a single rod that is received by the central spherical bearing, in particular an inner bushing, which is arranged in the bearing eye of the head. Here, the head is preferably formed integrally with the front end plate of the housing.

[0029] To allow axial translational movement of the journals relative to the housing, the journals preferably extend eccentrically from the central spherical bearing. For this purpose, the inner bushing can have a seat, e.g., a cylindrical bore, which receives the journals, in particular the single rod that is arranged eccentrically with respect to a central longitudinal axis of the bushing. Due to this eccentric design of the central spherical bearing, a rotational movement of the journals about a central axis of the bearing eye can have a translational component in the axial direction.

[0030] The movements of the external structure relative to the linear unit due to deformation of the external structure and / or thermal expansion of the linear unit, or at least some of its components, are small compared to the dimensions of the linear unit, for example, on the order of a few millimeters. The central spherical bearing can be a deformable spherical bearing. Advantageously, the deformable spherical bearing comprises an elastic material surrounding an inner bushing in which the journals are mounted. In particular, the elastic material is arranged between an inner bushing and an outer bushing that is coaxial with the inner bushing. The bushings can have spherical surface areas facing each other, with the elastic material positioned between them. By using a deformable central spherical bearing, it is possible to absorb vibrations.Furthermore, a certain degree of stiffness in a predefined direction can be provided as needed, which is advantageous for standard operation of the linear unit.

[0031] As mentioned above, the bearing shells can form spherical bearings to allow pivoting movement of the pins within the bearing shells, thus further increasing the degrees of freedom for moving and / or aligning the linear unit with respect to the external structure. For this purpose, at least one of the mounting arrangements preferably comprises bearing discs rotatably mounted in the bearing shells of the mounting arrangement. Preferably, each bearing disc has a recess that receives the respective pin. The bearing shells can each have a spherical inner surface area that is complementary to a spherical surface of the respective bearing disc. Thus, the bearing discs are pivotable within a cavity formed by the spherical inner surface of the bearing shells.If the bearing shells are fixed to the external structure, the pins received by the bearing disc sockets can therefore pivot relative to the external structure.

[0032] In addition or alternatively, to compensate for compression or elongation of the external structure and / or the linear unit, the pins of at least one of the fastening arrangements are preferably movable in the bearing shells in a direction perpendicular to the longitudinal axis of the pins, in particular parallel to the spindle.

[0033] For example, at least one of the fastening arrangements can comprise bearing discs rotatably mounted in the bearing shells, each bearing disc having a socket that receives one of the pins. Preferably, the pins have two parallel flat surfaces that contact opposite inner surfaces of the sockets. Advantageously, the sockets are elongated so that the pins are translationally movable within the sockets. For example, the sockets can be formed by elongated holes in the bearing discs. Accordingly, each of the pins can move translationally within its bearing shell perpendicular to its longitudinal axis.

[0034] Alternatively, translational movement of the journals within the bearing shells can be achieved by providing at least one fastening arrangement comprising bearing discs rotatably mounted in the bearing shells, each bearing disc having a socket that receives one of the journals. Advantageously, the sockets are arranged eccentrically on the bearing discs. A rotation of the journals about a central axis of the bearing discs or the bearing shells also has a component in the axial direction, i.e., parallel to the spindle.

[0035] The system according to a second aspect of the invention comprises a first component and a second component, which is movable, in particular pivotable, with respect to the first component. Preferably, a linear unit according to the first aspect of the invention is attached to the first component by means of the fastening system, in particular the two fastening arrangements, and the second component is coupled to the nut of the linear unit.

[0036] In this configuration, the linear unit is preferably suspended from the first component. In particular, this configuration can prevent or at least significantly reduce the effects of loads on the linear unit, especially its spindle, caused by deformation of the first component and / or thermal expansion of the linear unit. In other words, deformations of the first component, such as bending, torsion, and / or compression / elongation, are not transferred to the linear unit. This can considerably extend the service life of the linear unit, especially its spindle.

[0037] The properties, features, and advantages of the invention described above, as well as the manner in which they are achieved, are explained in more detail in the following description of examples, in conjunction with the figures. Where appropriate, the same reference numerals in the figures are used for the same or corresponding elements of the invention. The examples serve to illustrate the invention and do not limit it to the combinations of features given herein, even with respect to functional features. Furthermore, any of the features disclosed in the above description and the following examples can be considered individually and combined accordingly with the features of any of the above embodiments and their further aspects.In particular, each of the features described above and below can be combined alone or in combination with other described features with the linear unit according to the first aspect of the invention and the system according to the second aspect of the invention.

[0038] They show, in particular schematically: Fig. 1 an example of a linear unit comprising two mounting arrangements; Fig. 2 an example of a headpiece in a cross-sectional view; Fig. 3 Another example of a headpiece in a cross-sectional view; Fig. 4. Another example of a headpiece in a three-dimensional view; Fig. 5 an example of two fastening arrangements in a side view; Fig. 6 Another example of two fastening arrangements in a side view; Fig. 7 an example of a flexible spherical bearing; and Fig. 8 is an example of a system comprising two components and a linear unit for pivoting the two components relative to each other.

[0039] Fig. Figure 1 shows an example of a linear unit 10 for converting a rotary motion, for example of a motor 18, into a translational motion. The linear unit 10 comprises a housing 12, a spindle 14 rotatably mounted in the housing 12, a nut 16 interacting with the spindle 14, and two fastening assemblies 30 for attaching the linear unit 10, in particular the housing 12, to an external structure (not shown). The two fastening assemblies 30 can form a fastening system.

[0040] The motor 18 is operatively coupled to the spindle 14 via a gearbox located in a gearbox 20. The gearbox 20 is located at a distal or rear end 12b of the housing 12. Rotation of the spindle 14 moves the nut 16 translationally along the spindle 14. The nut 16 is coupled to a slide 22 located outside the housing 12, so that the slide 22 moves along with the nut 16. The movement of the slide 22 along the housing 12 is guided by guide rails 24 located on an upper side of the housing 12. The slide 22 includes a mounting structure 26 for attaching a component, for example, a machine part, to the slide 22.

[0041] The fastening arrangements 30 each comprise two pins 32 which are movably mounted in bearing shells (in Fig. The two pins 32 of each mounting arrangement 30 extend perpendicular to a longitudinal axis L of the linear unit 10, in particular to the spindle 14. Advantageously, the two pins 32 of each mounting arrangement 30 are arranged on opposite sides of the linear unit 10, in particular the spindle 14. The linear unit 10 can thus be attached to the external structure at four mounting points.

[0042] Each pin 32 includes a mounting base 32a for securely attaching the respective pin 32 to the external structure. The mounting bases 32a may include through holes 32c for screwing the pins 32 to the external structure (for clarity, only one through hole 32c is shown with a reference symbol).

[0043] One of the mounting arrangements 30 is arranged at the rear end 12b of the housing 12. The other mounting arrangement 30 is arranged at a head piece 40 of the linear unit 10, the head piece 40 being attached to a proximal or front end 12a of the housing 12.

[0044] Preferably, the pins 32 of the fastening assembly 30, which is arranged at the rear end 12b, are rotatably mounted only in their respective bearing shells. In other words, the components of the fastening assembly 30 are all axially fixed. However, the pins 32 of the fastening assembly 30, which is arranged on the headpiece 40, are preferably movably mounted in their respective bearing shells such that movement of the headpiece 40 is permitted with respect to additional degrees of freedom, i.e., not only rotation but also axial and radial movements. Alternatively or additionally, the headpiece 40 can be attached to the housing 12 in such a way that at least some of the additional degrees of freedom are provided.

[0045] Accordingly, the cones follow in the example of 32. Fig. 1. Any movement caused by a deformation of the external structure. Since the pins 32 of the front mounting assembly 30 are movably mounted in their bearing shells and / or the head piece 40 is movably mounted at the front end 12a, the linear unit 10 can maintain its initial orientation. In other words, any deformation, e.g., bending, torsion, and / or compression / elongation, of the external structure can be compensated by movement of the pins 32 in the respective bearing shell and / or the head piece 40 relative to the housing 12. Likewise, thermal expansion of the linear unit 10 or some of its components, in particular its spindle 14, can be compensated by movement of the pins 32 relative to the respective bearing shell. In this respect, the linear unit 10 can be freely suspended from the external structure at its front end 12a by the mounting assemblies 30.Due to the inherent rigidity of the components of the linear unit 10, in particular the housing 12, the mounting arrangements 30 can be considered self-aligning.

[0046] Fig. Figure 2 shows an example of such a head piece 40 in a cross-sectional view. Here, the head piece 40 is movably attached to a front end plate 50 of the housing 12. The front end plate 50 closes the housing 12 at its front end 12a near a free end of the spindle 14.

[0047] The head piece 40 comprises a cylindrical bore 42 that accommodates an axial projection 52 of the front end plate 50. The axial projection 52, which preferably extends along the longitudinal axis L, is axially movable within the cylindrical bore 42. This allows for compensation of, for example, thermal expansion of the linear unit or extension / compression of the external structure E due to external loads.

[0048] Additional degrees of freedom for positioning and / or aligning the external structure E with respect to the linear unit can be provided by equipping the axial projection 52 with a convex, preferably spherical, annular surface area 54a. The surface area 54a can be formed by a curvature 54 of the lateral surface 52a of the projection 52. Preferably, under load, the surface area 54a makes point contact with an inner wall of the cylindrical bore 42. This type of point contact between the axial projection 52 and the head 40 allows the head 40 to pivot about the axial projection 52 and also enables translational movement along the spindle axis.

[0049] In the Fig. In the example shown, the pins 32 are fixedly attached to the external structure E via the mounting bases 32a. Specifically, the linear unit is arranged between two walls of the external structure E, with the pins 32 passing through openings in the walls. The pins 32 are received in recesses 44 of the head piece 40. Here, the recesses 44 form the bearing shells 34 of the mounting assembly 30, which is arranged on the head piece 40. To allow the pins 32 to rotate within the bearing shells 34, bushings 36 can optionally be arranged in the bearing shells 34 / recesses 44.

[0050] Preferably, the pins 32 have axial play D in the recesses 44. Thus, the pins 32 can move translationally along their longitudinal axis A, thereby enabling self-alignment of the fastening arrangement 30 on the head piece 40 when the external structure E is bent in the plane of the figure. Fig. 2 is made possible.

[0051] Fig. Figure 3 shows another example of a headpiece 40 in a cross-sectional view. Similar to the one in Fig. In the example shown, the head piece 40 is movably attached to the front end plate 50 of the housing 12.

[0052] The head piece 40 comprises a preferably spherical cavity 46 in which a central bearing disk 48 is received. An inner surface region 46a of the cavity 46 is designed to be complementary to the spherical surface region 48a of the central bearing disk 48. The central bearing disk 48 is thus pivotable within the cavity 46. In other words, the head piece 40 and the central bearing disk 48 form a spherical bearing.

[0053] Preferably, the central bearing disk 48 comprises the cylindrical bore 42 in which the axial projection 52 of the front end plate 50 is received. Here, the axial projection 52 is cylindrical, that is, it has a flat lateral surface 52a, so that it is only linearly movable within the cylindrical bore 42.

[0054] Furthermore, the pins 32 of the fastening arrangement 30 are, in contrast to the one in Fig. In the example shown in Figure 2, the pins 32 are fixedly attached to the head piece 40. In particular, the pins 32 are integrally formed with the head piece 40, i.e., they are formed in one piece with the head piece 40. The free ends of the pins 32 are movably attached in the bearing shells 34, which may be fixedly attached to the external structure E.

[0055] In the present example, the journals 32 are not only rotatable but also pivotable in the bearing shells 34, particularly with respect to a bearing shell center axis X (indicated by a dashed line). For this purpose, the fastening arrangement 30 comprises bearing discs 38, which provide a seat for the free ends of the journals 32. The bearing discs 38 each comprise a spherical surface region 38a. An inner surface region 34a of the bearing shells 34 is designed to be complementary, so that the bearing shells 34 and the bearing discs 38 together form a spherical bearing.

[0056] The bearing shells 34 further comprise bores 38b which receive the journals 32. The bores 38b thus form the seats for the journals 32 in the bearing shells 34.

[0057] Preferably the pins 32, at least their free ends, are axially movable in the bores 38b, i.e. along their longitudinal axis A (which is indicated by a dashed line) - and thus, when the bearing shells 34 are attached to a mounting surface of the external structure E, movable perpendicular to the mounting surface.

[0058] Fig. Figure 4 shows another example of a headpiece 40 in a three-dimensional view. Here, the headpiece 40 is fixedly attached to the front end plate 50 of the housing 12. The headpiece 40 includes a bearing eye 64 in which a central spherical bearing 56 is arranged. Preferably, the pins 32 extend from the central spherical bearing 56 on both sides of the bearing eye 64. The spherical bearing 56 allows not only rotation of the pins 32, but also pivoting about the central axis of the bearing eye 64.

[0059] In this example, the pins 32 can be formed by a single rod 58 passing through the bearing eye 64 and the seat provided by the spherical bearing 56.

[0060] Fig. Figure 5 shows an example of two mounting arrangements 30 in a side view. A linear unit 10 is attached to an external structure E by the mounting arrangements 30.

[0061] One of the mounting assemblies 30 is arranged at a rear end 12b of a housing 12 of the linear unit 10. The mounting assembly 30 comprises two pins 32 (only one of which is visible) which are rotatably mounted in bearing shells 34 (only one of which is also visible). To allow rotation, a bushing 36 is arranged radially between each pin 32 and the corresponding bearing shell 34.

[0062] The other of the mounting assemblies 30 is arranged on a headpiece 40 of the linear unit 10. The headpiece 40 is attached to the housing 12, in particular to a front end plate therein (not specified), at a front end 12a of the housing 12. Pins 32 of the mounting assembly 30 are also movably mounted in bearing shells 34.

[0063] In contrast to the fastening arrangement 30 at the rear end 12b, the pins 32 of the fastening arrangement 30 on the head piece 40 are not only rotatable in the respective bearing shell 34, but also pivotable. For this purpose, the pins 32 are seated in bearing discs 38. The bearing discs 38 form spherical bearings with the corresponding bearing shells 34, as described in connection with Fig. 3 was explained in more detail.

[0064] Furthermore, the pins 32 are also in their bearing shells 34 in a direction perpendicular to a longitudinal axis of the pins 32 (which is perpendicular to the plane of the figure in Fig. 5 is) movable translationally in the direction running. In particular, the pins 32 can be movable translationally in a direction running parallel to a longitudinal axis L of the linear unit 10.

[0065] For this purpose, the pins 32 of the fastening arrangement 30 on the head piece 40 comprise two parallel flat surfaces 32b which touch the inner surfaces 60a of a socket 60 in the bearing discs 38.

[0066] The sockets 60 thus define the seats of the pins 32 in the bearing shells 34.

[0067] Advantageously, the sockets 60 are elongated and the pins 32 have play in the elongated sockets 60 perpendicular to their longitudinal axis.

[0068] Fig. Figure 6 shows another example of two fastening arrangements 30 in a side view. As in Fig. 5 is a linear unit 10 attached to an external structure E by the fastening arrangements 30.

[0069] The fastening arrangements 30 correspond to those in Fig. The five mounting arrangements shown are different. The only difference is that the translational mobility of the pins 32 of the mounting arrangement 30, which is arranged on the head piece 40, is not achieved by elongated sockets, but by an eccentric arrangement of the sockets 60 on the bearing disks 38. In other words, the sockets 60 that receive the pins 32 are arranged at a distance from a center point of the bearing disks 38. As a result, when the bearing disks 38 rotate in the bearing shells 34, the pins 32 follow a curved path and move translationally perpendicular to their longitudinal axis. This translational movement along the curved path also has a component parallel to the longitudinal axis L of the linear unit 10.

[0070] In the example shown, the center point of the bearing shells 34 of the mounting assembly 30 on the head piece 40 – and thus the pivot point or pivot axis of the bearing discs 38 in the bearing shells 34 – is radially offset O from the longitudinal axis L. The offset O is preferably selected such that, when the linear unit 10 is in a neutral position with respect to the external structure E, i.e., without deformation of the external structure E and without thermal expansion of the linear unit 10, the pins 32 are at the same height, i.e., arranged in a plane parallel to the longitudinal axis. In particular, the longitudinal axis L and the center of the pins 32, or at least their sockets 60, lie in the same plane.

[0071] Fig. Figure 7 shows an example of a flexible spherical bearing in cross-section. This type of spherical bearing can be, for example, a centered spherical bearing (reference numeral 56 in [reference number]). Fig. 4) can be used. The flexible spherical bearing comprises two coaxially aligned bushings 62a, 62b, between which an elastic material 66 is arranged. The inner bushing 62a has a circumferential surface that is at least partially convex, preferably spherical. The outer bushing 62b has a complementary inner surface that is at least partially concave, preferably spherical. In an alternative embodiment, however, the bushings 62a, 62b can have flat circumferential and inner surfaces, respectively. By using such a flexible spherical bearing, the radial stiffness required for standard operation can be provided, with radial, torsional, axial, and conical degrees of freedom being achieved by the elastic material 66 in predetermined directions as required.

[0072] In addition to or as an alternative to using the flexible spherical bearing as a central spherical bearing, such flexible spherical bearings can also be used to movably attach journals to an external structure. In particular, such flexible spherical bearings can replace the spherical bearings formed by bearing discs and bearing shells, e.g., as shown in [reference]. Fig. 3 can be formed, in principle, to replace them. For example, the bearing discs and bearing shells that are in Fig. 3 are shown, provided with the flexible material 66, which is arranged between them.

[0073] Fig. Figure 8 shows an example of a system 100 comprising a first component 102 and a second component 104 pivotally attached to the first component 102. The system 100 further comprises a linear unit 10 attached to the first component 102 by two mounting assemblies 30. A nut (not shown) of the linear unit 10 is coupled to the second component 104 such that, during a linear translational movement of the nut, the second component 104 pivots about a joint 106 relative to the first component 102. The connection between the nut and the second component 104 can be achieved by a slide that engages a mounting structure 26 (see Figure 8). Fig. 1) and a connector 108 which is attached at one end to the fastening structure 26 and at the opposite end to the second component 104.

[0074] The two mounting arrangements 30 allow the linear unit 10 to be decoupled from deformations of the first component 102, which may be caused, for example, by a load exerted by the second component 104. Likewise, one of the mounting arrangements 30 can self-align in the event of thermal expansion of the linear unit 10, thus preventing any load from being generated. Reference symbol list 10 linear units 12 cases 12a front end 12b rear end 14 spindles 16 Mother 18 engine 20 gearboxes 22 sleds 24 guide rail 26 Mounting structure 30 Mounting arrangement 32 cones 32a Mounting base 32b flat surface 32c Through holes 34 bearing shell 34a Interior surface area 36 socket 38 bearing disc 38a spherical area 38b bore 40 Headpiece 42 bore 44 In-depth study 46 cavity 46a Interior surface area 48 central bearing disc 48a spherical area 50 front end plate 52 lead 52a lateral area 54 Curvature 54a convex annular area 56 central spherical bearing 58 bars Version 60 60a Internal surface 62a inner socket 62b outer socket 64 Bearing eye 66 elastic material 100 System 102 first component 104 second component 106 joint 108 connectors E external structure L Longitudinal axis A Longitudinal axis X bearing shell center axis D game O offset

Claims

[1] Linear unit (10) for converting a rotational motion into a translational motion, comprising: - a case (12), - a spindle (14) which is rotatably mounted in the housing (12), - a nut (16) that interacts with the spindle (14), and - two fastening arrangements (30) for attaching the housing (12) to an external structure (E), wherein the fastening arrangements (30) each comprise at least two pins (32) arranged transversely to the spindle (14), the pins (32) being movably mounted in bearing shells (34) arranged on opposite sides of the spindle (14). [2] Linear unit (10) according to claim 1, wherein the pins (32) of at least one of the fastening arrangements (30) are rotatably fastened in their respective bearing shells (34). [3] Linear unit (10) according to claim 1 or 2, wherein the pins (32) of at least one of the fastening arrangements (30) are axially translationally movable with respect to their respective bearing shells (34). [4] Linear unit (10) according to one of the preceding claims, wherein one of the fastening arrangements (30) is arranged on a head piece (40) of the linear unit (10), the head piece (40) being attached to a front end plate (50) of the housing (12). [5] Linear unit (10) according to claim 4, wherein the head piece (40) is pivotably attached to the front end plate (50) of the housing (12) and / or is axially translationally movable with respect to the front end plate (50) of the housing (12). [6] Linear unit (10) according to claim 5, wherein the head piece (40) comprises a cylindrical bore (42) in which an axial projection (52) of the front end plate (50) is received, wherein the projection (52) has a lateral surface (52a) with an annular convex curvature (54). [7] Linear unit (10) according to claim 5, wherein the head piece (40) comprises a cavity (46) with an inner surface area (46a) which is complementary to a spherical surface area (48a) of a central bearing disk (48), so that the central bearing disk (48) is pivotable in the cavity (46), and the central bearing disk (48) comprises a cylindrical bore (42) in which an axial cylindrical projection (52) of the front end plate (50) is axially translationally movable. [8] Linear unit (10) according to one of claims 4 to 6, wherein the pins (32) of at least one of the fastening arrangements (30) have a fastening base (32a) for firmly attaching the pins (32) to the external structure (E) and the bearing shells (34) of one of the fastening arrangements (30) are arranged in the head piece (40). [9] Linear unit (10) according to one of claims 4 to 7, wherein the pins (32) of one of the fastening arrangements (30) extend from the head piece (40) on opposite sides and are pivotably mounted in the bearing shells (34) with respect to the bearing shell central axis (X). [10] Linear unit (10) according to claim 9, wherein the head piece (40) comprises a bearing eye (64) in which a central spherical bearing (56) is arranged, wherein the pins (32) extend from the central spherical bearing (56) on both sides of the bearing eye (64). [11] Linear unit (10) according to claim 10, wherein the pins (32) extend eccentrically from the central spherical bearing (56). [12] Linear unit (10) according to one of claims 10 or 11, wherein the central spherical bearing (56) is a deformable spherical bearing comprising an elastic material (66) surrounding an inner bushing (62a) in which the pins (32) are mounted. [13] Linear unit (10) according to one of the preceding claims, wherein at least one of the fastening arrangements (30) comprises bearing discs (38) rotatably mounted in the bearing shells (34) of the fastening arrangement (30), wherein the bearing discs (38) each have a socket (60) which receives the respective pin (32), and the bearing shells (34) each have a spherical inner surface area (34a) which is complementary to a spherical surface area (38a) of the respective bearing disc (38), so that spherical bearings are formed. [14] Linear unit (10) according to one of the preceding claims, wherein the pins (32) of at least one of the fastening arrangements (30) in the bearing shells (34) are translationally movable in a direction perpendicular to a longitudinal axis (A) of the pins (32). [15] Linear unit (10) according to claim 14, wherein at least one of the fastening arrangements (30) comprises bearing discs (38) rotatably mounted in the bearing shells (34), the bearing discs (38) each having a socket (60) that receives one of the pins (32), and the pins (32) having two parallel flat surfaces (32b) that contact opposite inner surfaces (60a) of the sockets (60), and the sockets (60) being elongated so that the pins (32) are translationally movable in the sockets (60). [16] Linear unit (10) according to claim 14, wherein at least one of the fastening arrangements (30) comprises bearing discs (38) rotatably mounted in the bearing shells (34), wherein the bearing discs (38) each have a socket (60) which receives one of the pins (32), and the sockets (60) are arranged eccentrically on the bearing discs (38). [17] System (100) comprising a first component (102) and a second component (104) movable with respect to the first component (102), wherein a linear unit (10) according to one of the preceding claims is attached to the first component (102) by the two fastening arrangements (30) and the second component (104) is coupled to the nut (16) of the linear unit (10).

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