Joint

The invention relates to a joint, in particular for use in a parallel kinematic positioning device, which has at least three rotational degrees of freedom, and which has a rigid carrier element and at least two elastically deformable joint devices arranged overlapping one another at least in sections on the carrier element, wherein each of the joint devices comprises two joint elements, and each of the joint elements has an elongated connecting section and a securing section arranged at one end of the connecting section for securing the joint device to a higher level unit, and the two connecting sections of each joint device extend in a direction pointing away from the carrier element in such a way that they cross over one another.

The invention relates to a joint and a positioning device with such a joint.

From DE 10 2017 115 050 B3 a solid body joint is known, which has at least three degrees of freedom of rotation and which attempts to simulate the bearing behavior of a ball joint, without, however, having its disadvantages with regard to the unavoidable breakaway torques. Although the solution disclosed therein with suitable solid joints is already close to the bearing properties of a ball joint, however, there are certain disadvantages due to different stiffnesses in the individual degrees of freedom of rotation, so that this solution is less suitable for certain applications.

It is therefore an object of the invention to provide a joint with at least three degrees of freedom of rotation, i.e. with the functionality of a ball joint, which comprises stiffnesses which with respect to the degrees of freedom of rotation are the same or approximately the same.

This object is achieved by a joint which comprises a rigid carrier element (2) and at least two elasticallv deformable joint devices (3), which are arranged at the carrier element (2) in an overlap at least in a section, wherein each of the joint devices (3) comprises two joint elements (4), and wherein each of the joint elements (4) comprises an elongated web section (5) and a fastening section (6) which is arranged at one end of the web section (4) for fastening the joint device (3) at a higher-level unit, and wherein the two web sections (4) of each joint device (3) extend in a direction which points away from the carrier element (2) in such a way that the same cross one another.

The term “essentially” which is used in the following part of the description in several places in connection with the specification of geometric data such as angles, dimensions, positions, orientations or directions, is to be understood as meaning that the corresponding geometric data may have a deviation of +/−5% compared to the respective specified geometric data, wherein this deviation is due, for example, to manufacturing or assembly tolerances.

The joint according to the invention, which comprises at least three degrees of freedom of rotation, comprises a rigid carrier element and at least two elastically deformable joint devices which are arranged at the carrier element in a covering or in an overlap of one another at least in a section.

Each of the two elastically deformable joint devices comprises two joint elements, wherein each of the joint elements comprise an elongated, preferably rod-shaped web section and a fastening section which is arranged at one end of the web section. This fastening section is provided in order to attach the joint to a higher-level unit or to an element of a higher-level unit in order to realize the desired mobility of the higher-level unit by means of the joint. The term “elongated web section” describes a web section whose longitudinal extension is significantly greater than its extension in the directions perpendicular to the longitudinal extension, i.e. its length is much greater than its width and thickness or height.

The two web sections of a joint device extend in a direction which points away from the carrier element in such a way that they cross one another in a mutually overlapping manner. The corresponding crossover area ensures a certain relative movement of the web sections with respect to one another in the crossover area, so that an advantageous mobility of the joint device results in case of a corresponding demands, in particular with regard to a rotational movement or tilting in a plane which extends parallel to the carrier element or in the plane of the support element.

In this connection it can be advantageous that the two web sections of a joint device at least in a section enclose an angle between them which amounts to between 60 degrees and 120 degrees, and preferably between 70 degrees and 95 degrees.

It can be advantageous that at least one web section and preferably both web sections of one joint device runs or run at least in a section between the two web sections of the other joint device. In other words, a web section or both web sections of one joint device pass through a frame or its opening formed by the two web sections of the other joint device. In this way, a crossing arrangement of the joint devices can be implemented comparatively easily.

It can also be advantageous that the web sections of a joint device are arranged to the web sections of the other joint device at an angle which amounts to between 60 degrees and 90 degrees. Such an arrangement results in a particularly effective function of the joint according to the invention.

In addition, it can be advantageous that the area of the crossing of the web sections of a joint device has a different distance from the support element than the area of the crossing of the web sections of the other joint device. In concrete terms, it can be advantageous for the area of the crossover of the web sections of one joint device to be arranged closer to the support element than the crossover area of the web sections of the other joint device.

Furthermore, it can be advantageous that one joint element comprises two fastening sections which are arranged at opposite ends of the web portion. The joint element can thus be fastened to the carrier element via one of the fastening sections, while the other fastening section of the same joint element is used for fastening to a superordinate unit or an element of a superordinate unit.

In addition, it can be advantageous that the joint elements are made in one piece, that is to say that the fastening section is realized or the fastening sections are realized in one piece or integrally with the web section. As a result, the parts of the joint element or of the entire joint are reduced so that the assembly of the joint is simplified and can be implemented more quickly or more cost-effectively.

In addition, it can be advantageous that all of the joint elements to have essentially the same geometry. This simplifies the production and manufacturing process.

It can also be advantageous that the two joint elements of a joint device are arranged in mirror image to one another. Thereby, in particular a symmetrical arrangement of the web sections of a joint device result in an equally symmetrical deformation behavior of the joint device, in particular in a largely identical flexibility around all degrees of freedom of rotation.

Furthermore, it can be advantageous that on the carrier element at least one elastically deformable support element is arranged. In this connection, it is particularly advantageous if the support element extends at least in a section between at least one of the two joint devices in a direction which points away from the support element. With the aid of the support element, a tensile force can be applied to the web sections of the joint elements in a simple manner, so that a pretensioning of the joint elements in the extension direction of the joint results.

Furthermore, it can be advantageous that the joint comprises four joint devices which are arranged at the support element and two support elements which are arranged at the support element, wherein the joint devices are located in pairs and the support elements are individually located at the opposite ends of the support element. Due to the corresponding symmetrical structure of the joint, a largely identical flexibility around all degrees of freedom of rotation is realized on both sides of the support element.

The invention also relates to a positioning device, in particular a parallel kinematic positioning device, with at least one of the previously described joint.

An exemplary embodiment of the invention is described below with reference to the singleFIG.1. The same shows an embodiment of a joint1according to the invention, which comprises a total of four joint devices3which are disposed at an essentially rigid carrier element2which consist of aluminum, wherein the joint devices3are elastically deformable or flexible and are made of spring steel. Other materials which comprise a corresponding elastic deformability or flexibility for use for the joint devices3are also conceivable, for example bronze, which is non-magnetic and can be used in case that the joint according to the invention is used in a magnetic field. In case that only very small deflections of the joint are intended, the joint devices can also be made of a ceramic material.

The carrier element2, which besides aluminum can also be made of another metal, for example of steel, or also of ceramic, has an essentially rectangular shape, wherein the middle area comprises a greater thickness, and the carrier element extends towards its two ends tapered in terms of its thickness.

Each joint device3comprises two identically shaped joint elements4, wherein each joint element4having an elongated, essentially rod-shaped web section5and two fastening sections6formed in one piece with this, which are arranged at the two opposite ends of the web section5. However, a one-piece design of the fastening sections6with the elongated web section5or a one-piece design of the joint elements4is not mandatory so that the fastening sections6can also be connected to the web section5or arranged on it in another way.

The fastening sections6of a joint element4have the same shape, wherein only the fastening sections6which are spaced apart by the carrier element2are clearly visible inFIG.1. Each of the two fastening sections6of a joint element4extends at the respective end of the web section5in a substantially flag-shaped manner to this, however the directions of extension of the fastening sections6at the opposite ends of the web section5are contrary to each other. Therefore, each joint element4has a substantially Z-shape. Each fastening section6also comprises two through bores or recesses60.

The two joint elements4of a joint device3have the same shape, but are arranged in mirror-image to one another, the respectively associated fastening sections6coming to overlap in such a way that the two through bores60of one fastening section6are arranged exactly over the through bores60of the adjoining and associated fastening section6. This makes it possible that a fastening element8in the form of a screw extends through the holes which are formed by the superimposed through holes and that a connection of the fastening section6to the carrier element2on the one hand and to an element100of a higher-level unit, on which or in which the joint according to the invention is installed or inserted, on the other hand, can be realized.

Due to the overlapping arrangement of the through bores60of two adjacent and associated fastening sections6, by the fastening element8, in addition to the connection with the carrier element2or the element100of a higher-level unit, a connection of the two joint elements4of a joint device3can be established. However, such a connection between the two joint elements4of a joint device3is not mandatory, so that the fastening sections6can also be designed in such a way that only the necessary fixation of the web section5between them is realized via them.

It is conceivable to realize the connection between the web sections5of a joint device3and the carrier element2not via screws, but via other types of connection such as soldering, welding, riveting or gluing. A one-piece or integral realization of the web sections5with the carrier element2while at the same time eliminating the corresponding fastening section6is also conceivable. It is conceivable by analogy to realize the connection between the web sections5of a joint device3and a higher-level unit not by means of screws, but also using the previously listed types of connection such as soldering, welding, riveting or gluing. Even a one-piece embodiment of the web sections5with the superordinate structure or unit is conceivable.

According toFIG.1, in each case on both the upper side21of the carrier element2and the underside22of the carrier element there are two joint elements4fastened via their corresponding fastening section6and with the use of a screw8. At the joint elements4of the corresponding joint device3which are attached to the upper side21of the carrier element2, the web sections5are arranged in such a way that they extend in a direction pointing away from the carrier element2and cross one another in the further course. That is, the web sections5extend from the carrier element2in a direction that deviates from the direction of extension of the carrier element or is inclined with respect to the same, wherein the angle of this direction with regard to the corresponding side surface of the carrier element2amounts to less than 90 degrees. In addition, the web sections5of the two joint elements4which are arranged on the upper side21of the carrier element2in a direction pointing away from the carrier element2in such a way that they extend inclined with regard to the plane which is spanned by the upper side21of the carrier element2. At the same time the two web sections5lie essentially in the same plane or emerge from the common plane only in the area of their crossing.

Also at the joint elements4of the corresponding joint device3which are mounted to the underside22of the carrier element2, the web sections5are arranged such that the same extend in a direction which points away from the carrier element2and which cross each other in the further course. However, the area of the crossing of the two web sections4of the joint elements4which are fastened to the underside22of the carrier element2is positioned further away from the carrier element or at a distance from the same than the area of the crossing of the two web sections4of the joint elements4which are attached at the upper side21of the carrier element2. As a result of the fact that the crossover areas are positioned at different distances from the carrier element2, the two web sections of the joint elements4which are fastened to the upper side21of the carrier element2can extend in a section between the two web sections5of the joint elements which are fastened to the underside22of the carrier element2or can pass through the same. In other words, the two web sections5of the hinge device3which is arranged on the underside22of the carrier element2, due to the crossover region which is positioned further away from the carrier element2, form a substantially triangular frame through which the two web sections5of the hinge device3which is arranged on the upper side21of the carrier element3can pass through. This means that the joint elements4of a joint device3or their web sections5also comprise an arrangement with a crossing over of one another, i.e. next to the crossing arrangement of the two web sections4of a joint device3.

Analogous to the web sections5of the joint device3which is arranged on the upper side21on the carrier element2, the web sections5of the two joint elements5which are arranged on the underside22of the carrier element2extend in a direction which points away from the carrier element2in such a way that the same are arranged inclined with regard to the plane which is spanned by the underside22of the carrier element2. At the same time the two web sections5lie essentially in the same plane or emerge from the common plane only in the area of their crossing.

The plane in which the two web sections5of the hinge device3which is arranged on the upper side21of the carrier element2does not extend parallel to the plane in which the two web sections5of the hinge device3which is arranged on the underside22of the carrier element2extend. The two planes described above enclose an angle which amounts to approximately 70 degrees.

At one of the two outward-facing ends or end portions of the carrier element2an elastically deformable, elongated and flat support element7is disposed, which, for reasons of clarity, has been omitted inFIG.1on the opposite side of the carrier element2. The support element7is with one of its end portions inserted in a corresponding recess of the carrier element2used and fixed at this position by means of a clamp connection. Other types of attachment, such as a screw connection, gluing, soldering, welding or the like are also conceivable.

The support element7extends with its elongated shape in a direction which points away from the carrier element2and comprises, at its opposite end, a widening end section, which cannot be seen inFIG.1, wherein the end section engages an element100of a superordinate unit or engages with a recess of an element100, preferably via a clamp connection. By connecting the support element7to the element100of a superordinate unit, the support element7is acted upon by a compressive force, and this compressive force causes a tensile load on the joint elements4and, in particular, a corresponding pretensioning of their web sections5in a direction which essentially coincides with the direction of extension of the support element or the joint.

LIST OF REFERENCE SYMBOLS