The present invention relates to a crimping element for holding a wire with a nominal diameter of approximately 0.1 mm or less. The invention also relates to a method for producing a crimping element of this type.
For compact actuators, use is increasingly being made of shape memory alloy wires, the shape, in particular the length, of which changes when heated, and thus convert thermal (or electrical) energy into mechanical work. Of late, shape memory alloy wires of this type are used as valve actuators in small, compact valves for filling and/or emptying a fluid bladder or fluid chamber in pneumatic adjusting devices of pneumatically adjustable vehicle seats. The shape memory alloy wires, in particular in applications of this type, are what are known as ultra-fine wires and have a diameter of approximately 0.1 mm or less. These wires or ultra-fine wires must be electrically and mechanically connected to a printed circuit board, for example, in a cost-effective and reliable manner. This is usually done by means of a crimping technique, in which the wire is crimped by a crimping element. The material of the crimping element is usually considerably softer than the material of the wire, with the result that the wire is held by the crimping element by means of clamping when it is being crimped. In the process, the crimping element produces the mechanical and electrical connection between the wire and the printed circuit board, for example.
However, it has been shown that the wire can easily slip out of the crimping element in certain circumstances. In particular when the shape and the length of the wire changes, these changes occurring in the event of variation in the loading and temperature of shape memory alloy wires, it is possible for the wire to be pulled out of the crimping element and therefore the mechanical and electrical connection is disrupted.
It is therefore an object of the present invention to provide a crimping element for holding a wire (ultra-fine wire) with a nominal diameter of approximately 0.1 mm or less, which also ensures that the wire is reliably held in the event of many variations in loading and temperature of the wire. It is furthermore an object of the present invention to provide a method for producing a crimping element of this type.
These objects are achieved by a crimping element according to patent claim 1, and by a method for producing a crimping element of this type according to patent claim 9. Advantageous refinements are the subject matter of the dependent claims.
According to a first aspect of the present invention, a crimping element for holding a wire (ultra-fine wire) with a nominal diameter of approximately 0.1 mm or less is provided. In this respect, the crimping element comprises a sheet-metal element, which has a base portion extending in a base plane and a holding portion connected to the base portion, wherein the holding portion has a first clamping element and a second clamping element, which is spaced apart from the first clamping element by means of a recess in the holding portion. In this context, the recess may be a slot-shaped recess, for example, which extends along a direction of longitudinal extent or axis. The first clamping element has a first clamping portion, which is connected to the base portion, and a second clamping portion, which is connected to the first clamping portion, wherein the first clamping portion and the second clamping portion form a first clamping region for holding the wire between the first clamping portion and the second clamping portion. The second clamping element has a third clamping portion, which is connected to the base portion, and a fourth clamping portion, which is connected to the third clamping portion, wherein the third clamping portion and the fourth clamping portion form a second clamping region for holding the wire between the third clamping portion and the fourth clamping portion.
In the crimping element according to the invention, the first clamping portion of the first clamping element extends in a first plane, which forms a first angle that, in terms of magnitude, is in a range of approximately 0° to approximately 10° with the base plane of the base portion. Furthermore, in the crimping element according to the invention, the third clamping portion of the second clamping element extends in a second plane, which forms a second angle that, in terms of magnitude, is in a range of approximately 1° to approximately 10° with the first plane of the first clamping element. In other words, the second clamping element and the third clamping portion is tilted with respect to the first clamping element and the first clamping portion, respectively. This tilted arrangement, or the fact that the second plane forms an angle that, in terms of magnitude, is in a range of approximately 1° to approximately 10° with the first plane, provides a crimping element that can twist or shear the wire present in the clamping regions. This shearing leads to particularly good clamping of the wire, with the result that the wire can be reliably held by the crimping element even in the event of high variations in loading and temperature.
According to a further preferred configuration, the second angle, which the second plane forms with the first plane, in terms of magnitude is in a range of approximately 2° to approximately 3°. In such a configuration, the first clamping portion is substantially only slightly tilted with respect to the third clamping portion, or the third clamping portion is substantially only slightly tilted with respect to the first clamping portion, wherein the tilting in this case is in the region of the nominal diameter of the wire, thereby having particularly good long-term stability when the wire is being held.
In a further preferred configuration, the first angle, which the first plane forms with the base plane of the base portion, is approximately 0°. In other words, in this respect the first clamping portion extends in continuation of the base portion. In this configuration, only the third clamping portion is tilted relative to the first clamping portion, or the first clamping portion is tilted relative to the third clamping portion. There is no additional tilting between the first clamping portion and the base portion, and therefore the crimping element does not need to be bent additionally between the base portion and the first clamping portion, which is why a crimping element of this type can be produced particularly cost-effectively and easily.
According to a further preferred configuration, the second clamping portion and the first clamping portion are bent (or folded) about a first bending axis (or folding axis) and the first bending axis extends substantially perpendicularly with respect to a direction of longitudinal extent of the recess. It is also advantageous when the fourth clamping portion and the third clamping portion are also bent (or folded) around a second bending axis (or folding axis) and the second bending axis extends substantially parallel to the first bending axis. Moreover, when the two bending axes largely coincide, the second and the fourth clamping portion can be bent at the same time and thus cost-effectively in the same work step.
In a further preferred configuration, the crimping element also has a wire with a nominal diameter of approximately 0.1 mm or less, wherein the wire is arranged in the first clamping region and in the second clamping region in such a way that the wire extends along a direction of longitudinal extent of the wire, which extends substantially parallel to the first bending axis and parallel to the second bending axis, in the first clamping region and in the second clamping region. In this configuration, the wire is subjected to particularly uniform clamping in the first and the second clamping region, since the wire runs substantially parallel to the first and the second bending axis.
In a further preferred configuration, the holding portion of the sheet-metal element has a third clamping element, which is spaced apart from the second clamping element by means of a recess in the holding portion. The further recess, in turn, may be a slot-shaped recess extending along a further direction of longitudinal extent or axis. In this configuration, the third clamping element also has a fifth clamping portion, which is connected to the base portion, and a sixth clamping portion, which is connected to the fifth clamping portion, wherein the fifth clamping portion and the sixth clamping portion form a third clamping region for holding the wire between the fifth clamping portion and the sixth clamping portion, and wherein the fifth clamping portion of the third clamping element extends in a third plane, which substantially coincides with the first plane of the first clamping element. In this configuration, a crimping element with three clamping regions is provided, wherein the first clamping element and the third clamping element, or the first clamping portion and the fifth clamping portion, extend substantially in the same plane, and wherein the second clamping element, located between the first clamping element and the third clamping element, is tilted with respect to the other two clamping elements. This configuration provides a symmetrical crimping element, in which the wire is held even better, since the wire is sheared or twisted respectively between the middle and the outer clamping element, as a result of which the wire being pulled out of the crimping element is prevented even more reliably. It is particularly advantageous when, in this configuration, moreover the second angle is in a range that, in terms of magnitude, corresponds to merely half of the range mentioned above, that is to say is in a range that, in terms of magnitude, is approximately 0.5° to approximately 5°, in particular, in terms of magnitude, is approximately 1° to approximately 1.5°. This particularly advantageous configuration is based on the idea that the wire is ultimately twisted twice in the case of the symmetrical configuration of the crimping element, and as a result tilting by a half angle, in each case, is sufficient for the wire to be reliably held.
A further preferred configuration of the crimping element according to the invention provides that the base portion also has contact elements, which are designed for making electrical and mechanical contact with an electrical printed circuit board. The contact elements may be connected to a printed circuit board by means of soldering, for example. In addition to mechanical holding, the contact elements also serve for making electrical contact with the wire, as a result of which easy mechanical and electrical attachment of the wire to the printed circuit board is possible, in particular in the case of shape memory alloy wires.
According to a second aspect of the present invention, a method for producing a crimping element for holding a wire with a nominal diameter of approximately 0.1 mm or less is provided, wherein the crimping element has a sheet-metal element with a base portion extending in a base plane and a holding portion connected to the base portion, and wherein the holding portion has a first clamping element and a second clamping element, which is spaced apart from the first clamping element by means of a recess in the holding portion, wherein the first clamping element has a first clamping portion connected to the base portion and a second clamping portion connected to the first clamping portion, and the second clamping element has a third clamping portion connected to the base portion and a fourth clamping portion connected to the third clamping portion, and the method comprises the following steps: bending the second clamping portion about a first bending axis in such a way that the second clamping portion and the first clamping portion form a first clamping region for holding the wire; bending the fourth clamping portion about a second bending axis in such a way that the fourth clamping portion and the third clamping portion form a second clamping region for holding the wire; and tilting the third clamping portion relative to the first clamping portion or tilting the first clamping portion relative to the third clamping portion in such a way that the first clamping portion and the third clamping portion form an angle in relation to one another that, in terms of magnitude, is in a range of approximately 1° to approximately 10°. As a result of the tilting according to the invention of the third clamping portion relative to the first clamping portion or the tilting according to the invention of the first clamping portion relative to the third clamping portion, a wire arranged in the two clamping regions is twisted or sheared between the two clamping regions and, as a result, can be held steadily and reliably by the crimping element.
In a particularly preferred configuration of the method according to the invention, the third clamping portion is tilted relative to the first clamping portion or the first clamping portion is tilted relative to the third clamping portion in such a way that the first clamping portion and the third clamping portion form an angle in relation to one another that, in terms of magnitude, is in a range of approximately 2° to 3°. The result of such an angle range is that the tilting of the clamping portions in relation to one another is in a region of a nominal diameter of the wire, as a result of which the wire is held particularly reliably and steadily in the crimping element.
In a further preferred configuration of the method according to the invention, the third clamping portion is tilted relative to the first clamping portion or the first clamping portion is tilted relative to the third clamping portion before the second clamping portion is bent about the first bending axis and before the fourth clamping portion is bent about the second bending axis. In other words, first of all a twisting of the wire is created by tilting the clamping elements in relation to one another, wherein the wire is not yet fixed in the clamping regions and can still slip out in the clamping regions. Only when the wire has been twisted or the clamping elements have been tilted in relation to one another is the wire ultimately fixed in the two clamping regions by bending the respective clamping portions. In this preferred configuration, the fatigue strength of the wire held in the crimping element can be increased.
Further features and objects of the present invention will become apparent to a person skilled in the art by practicing the present teaching and taking into consideration the accompanying drawings. In the figures:
Elements of identical design or function are provided with the same reference signs across all figures.
Reference is made firstly to
The clamping elements 18, 20 and 22 are also bendable or foldable along a bending axis 32. Thus, for example, the first clamping element 18 is bendable along a first bending axis 34, the second clamping element 20 is bendable along a second bending axis 36, and the third clamping element 22 is bendable along a third bending axis 38. In the specific example of
The first clamping element 18 also has a first clamping portion 40, which is connected to the base portion 14, and a second clamping portion 42, which is connected to the first clamping portion 40. The second clamping element 20 has a third clamping portion 44, which is connected to the base portion 14, and a fourth clamping portion 46, which is connected to the third clamping portion 44. The third clamping element 22 has a fifth clamping portion 48, which is connected to the base portion 14, and a sixth clamping portion 50, which is connected to the fifth clamping portion 48. The respective clamping portions of the respective clamping elements 18, 20, 22 are foldable or bendable toward one another along the respective bending axes 34, 36, 38, in order to form clamping regions for holding a wire, as will be described in more detail in conjunction with
As is also shown in
Reference will now be made to
Specifically, the second clamping portion 42 and the first clamping portion 40 of the first clamping element 18 are bent toward one another about the first bending axis 34 in such a way that the first clamping portion 40 and the second clamping portion 42 form a first clamping region 54 between the first clamping portion 40 and the second clamping portion 42 for the purpose of holding a wire 56. Furthermore, the third clamping portion 44 and the fourth clamping portion 46 are bent toward one another about the second bending axis 36 in such a way that the third clamping portion 44 and the fourth clamping portion 46 form a second clamping region 58 between the third clamping portion 44 and the fourth clamping portion 46 for the purpose of holding the wire 56. Lastly, the fifth clamping portion 48 and the sixth clamping portion 50 are bent toward one another about the third bending axis 38 in such a way that the fifth clamping portion 48 and the sixth clamping portion 50 form a third clamping region 60 between the fifth clamping portion 48 and the sixth clamping portion 50 for the purpose of holding the wire 56.
In the specific example of
On account of the fact that the bending axes 34, 36, 38 are parallel to one another or coincide to form a common bending axis 32, and each of the bending axes 34, 36 and 38 extends substantially perpendicularly with respect to the directions of longitudinal extent 28, 30 of the two recesses 24, 26, it is possible to arrange the wire 56 in the clamping regions 54, 58 and 60 in such a way that a direction of longitudinal extent 61 of the wire 56 runs substantially parallel to the bending axes 34, 36 and 38.
Reference will now be made to
In the specific example of
In order ultimately to not subject the wire 56 to unnecessary loading or damage when it is being held in the crimping element 12, when the crimping element 12 is being produced first of all the third clamping portion 44 is tilted relative to the first clamping portion 40 and only then are the clamping portions 42, 46 and 50 bent about the respective bending axis 34, 36, 38. Such a sequence of the processing steps of the sheet-metal element 10 has the result that, when the third holding portion 44 is being tilted or when the second clamping element 20 is being tilted, the wire 56 is not yet completely fixed and the wire 56 can thus slip out, before, in the subsequent step, lastly the wire 56 is fixed in its offset and ultimate position by bending the clamping portions 42, 46 and 50. This selection or sequence of the processing steps of the sheet-metal element 10 largely avoids stretching or shearing of the wire 56 during the tilting operation, as a result of which the wire 56 is damaged less and the wire 56 thus has greater long-term stability.
In
By contrast,
In the specific example of
A value of approximately 9° for the second angle 68 is obtained, for example, when the wire 56 has for example a spacing 70 of an order of magnitude of approximately 2 mm from an axis of rotation 72, about which the second clamping element 20 is rotated or tilted relative to the first clamping element 80, and moreover the third clamping portion 44 is tilted relative to the first clamping portion 40 by a thickness of 0.3 mm, which corresponds to the material thickness of the sheet-metal element 10, for example.
However, if the third clamping portion 44 is tilted much less, for example only by a nominal diameter of the wire 56, considerably smaller values result for the second angle 68. When the wire 56 has a nominal diameter of 0.076 mm, for example, and the third clamping portion 44 is tilted relative to the first clamping portion 40 only by the nominal diameter, given a spacing 70 of the order of magnitude of approximately 2 mm between the wire 56 and the axis of rotation 72 the result is a value for the second angle 68 of approximately 2°. Such a small tilt has the result that the wire 56 is not only held reliably, but at the same time the material stress that acts on the sheet-metal element 10 when the third clamping portion 44 is being tilted relative to the first clamping portion 40 is comparatively low. This increases the long-term stability of the wire 56.
Reference will now be made to
Reference will now be made to
Of course, other embodiments of the crimping element 12 according to the invention are conceivable. It is possible, for example, for the fifth clamping portion 50 to extend in a third plane that coincides with the first plane 64 of the first clamping portion 40. However, it is also conceivable for the fifth clamping portion 50 to extend in a third plane that does not coincide with the first plane 64, but forms a predetermined angle in relation to it. In all other respects, it is also conceivable for the third plane to likewise form a (identical or different) predetermined angle in relation to the second plane 66.
By virtue of the tilting of the clamping elements 18, 20, 22 or the clamping portions 40, 44, 48 in relation to one another, the crimping element 12 according to the invention ensures that the wire 56 is held reliably in the clamping regions 54, 58, 60 even in the event of frequent variations in loading and temperature. This is particularly advantageous for shape memory alloy wires, which are used as actuators for valves in pneumatic adjusting devices, since these wires are exposed to frequent variations in loading and temperature.
Although the crimping element 12 is shown in the form of an element consisting of three clamping elements 18, 20, 22 in conjunction with
In all other respects, it should be noted that
Number | Date | Country | Kind |
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10 2020 204 229.2 | Apr 2020 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/DE2021/200022 | 2/25/2021 | WO |