Patent Application
20180283363
The present embodiments relate to a spring unit, a spring accumulator, and an actuator.
Spring elements are used often in mechanical engineering. For example, mechanical accumulators in the form of spring accumulators are widespread. Spring elements typically include a part that may be deflected with a deflection s. A spring force acts with a spring stiffness k on the part that may be deflected in accordance with Hooke's law:
F=k·s.
The spring force thus increases with increasing deflection of the part that may be deflected.
For example, actuators include spring elements as described above. Actuators of this kind, and thus also the spring elements, are typically deflected, where the spring elements are often part of spring accumulators, either explicitly (e.g., as additional components with accumulator function) or implicitly (e.g., as components such as piezoelectric stacks or seal elements, such as bellows of appropriate stiffness). The characteristics of the actuator (e.g., force profile and speed profile) therefore do not have the desired form over the deflection, since the spring force of the spring elements is dependent on the extent of the deflection. This provides that the dependency on deflection is too great for many applications.
It is known to use spring elements that have low stiffness so that the spring force in the event of deflection is limited.
Such solutions, however, provide disadvantageously sensitive limitations in the parameter selection for these spring elements.
The scope of the present invention is defined solely by the appended claims and is not affected to any degree by the statements within this summary.
The present embodiments may obviate one or more of the drawbacks or limitations in the related art. For example, an improved spring unit including a spring element, in which dependency of a spring force on a deflection has a less disruptive effect, is provided. In another example, an improved spring accumulator and an improved actuator are provided.
The spring unit according to one or more of the present embodiments includes at least one spring element that has a part that may be deflected against a spring force, and a compensation device. The compensation device is configured, at least along a segment along which the part may be deflected, to counteract the spring force more strongly in the case of a more greatly deflected part than in the case of a less greatly deflected part. The segment may include, for example, the case of vanishing deflection. The segment may include all paths that may be described by the part with the deflection thereof, below a maximum path or path value.
A part of a spring element that may be deflected, within the sense of the present embodiments, for example, provides a free end of a compression spring or tension spring or a freely movable non-end or non-edge region of a spring element (e.g., the disc center of a disc spring).
The compensation device thus advantageously counteracts the dependency of the spring force on the deflection of the part that may be deflected. In this way, a spring unit and, for example, a spring accumulator including a spring unit of this kind, and an actuator with a significantly reduced deflection dependency of the application of force on the free part of the spring element may be formed. The significant reduction of this dependency of the application of force thus opens up new fields of use for spring accumulators and actuators that previously were not available on account of the dependency.
Due to the compensation device, the influence of the dependency of the spring force on the deflection may be eliminated. This is important, for example, in the case of metal or diaphragm bellows that provide a metallic seal alongside length compensation. These bellows form spring elements and have a certain stiffness, whereby a force is built up in the event of a deflection. In accordance with one or more of the present embodiments, this influence of force may be easily reduced. For example, it is not necessary to use a bellows that is as soft as possible.
In the spring unit according to one or more of the present embodiments, the compensation device may include a body that may be deflected together with the part along a path, and also one or more clamping jaws that clamp the body in the direction transverse to the path.
In a development of the spring unit, the body has a convex contour as considered in the direction of the one or more clamping jaws. In this way, a force counteracting the spring force may be exerted onto the body by a clamping action.
In the spring unit according to one or more of the present embodiments, the contour when the part is not deflected may have a tangent on the one or more clamping jaws that is parallel to the path. The one or more clamping jaws thus behave in a neutral manner on the part when the part is not deflected.
In the case of the spring unit according to one or more of the present embodiments, the contour of a more strongly deflected part may have a tangent on the one or more clamping jaws that is inclined relative to the path. An increasing force counteracting the spring force may be applied to the part accordingly.
In a development, the contour of the spring unit is an outer contour. Alternatively or additionally, the contour is an inner contour.
In the case of the spring unit according to one or more of the present embodiments, the body may be resilient. The spring accumulator according to one or more of the present embodiments includes a spring unit as described above.
In the spring accumulator according to one or more of the present embodiments, the compensation device may be formed with a spring accumulator. The, for example, resilient body between the clamping jaws may function as a further energy accumulator of this kind (e.g., the entire spring accumulator inclusive of compensation device functions in this development as an energy accumulator).
The actuator according to one or more of the present embodiments includes a spring unit as described above and/or a spring accumulator as described above. The functionality of the actuator may thus be significantly improved, since in accordance with the present embodiments, the force-path characteristics of an actuator of this kind are not influenced by spring elements, as are formed, for example, by metal or diaphragm bellows. This is important, for example, in the case of smaller actuators (e.g., microactuators), since the force-path reserves are usually low and even small spring stiffnesses may have a large negative influence.
The spring accumulator shown in
The clamping body 20 has a longitudinal section that remains the same in different cuts parallel to the drawing plane (e.g., the clamping body 20 forms a general mathematical cylinder, the generatrix of which runs perpendicular to the drawing plane). The outer contour 25 of the longitudinal section of the clamping body 20 has a convex curved course, as considered outwardly in the direction perpendicular to the axis A.
The clamping body 20 bears, in a direction perpendicular to the axis A, against two clamping jaws 30, 35 that are oriented as roller bearings with rolling axes perpendicular to the drawing plane and are arranged fixedly relative to the sides 13, 17 of the actuator. In further exemplary embodiments (not shown specifically), the clamping jaws may also be formed as plain bearings.
The clamping body 20 is formed in a flexible manner and is clamped by the clamping jaws 30, 35, and at the same time is compressed in the direction perpendicular to the axis A and within the drawing plane. In the non-deflected position of the clamping body 20 according to
With increasing deflection (
With a further deflection of the clamping body 20, the clamping jaws 30, 35, on account of the convex outer contour of the clamping body 20 (e.g., as considered outwardly in the direction perpendicular to the axis A), bear against a point such that the tangents on the outer contour at the location of the clamping jaws 30, 35 enclose a larger angle with the axis A compared to the position according to
The contour of the clamping body 20 in the shown exemplary embodiment has such a course that the total force acting on the clamping body 20 along the axis A is practically constant (e.g., is practically independent of the deflection of the clamping body 20).
In the extreme case, the outer contour of the clamping body 20 may be selected in a further exemplary embodiment (not shown specifically) such that the force Fx conveyed by the clamping jaws 30, 35 always offsets the spring force Fk on the clamping body 20. The clamping body 20 thus remains free of force with each deflection. Consequently, the clamping body 20 is stopped in each deflected position in exemplary embodiments of this kind.
The clamping jaws 30, 35 do not have to act on the outer contour of the clamping body 20 as presented above. Rather, the clamping body 20 may have a corresponding inner contour that is acted on by the clamping jaws 30, 35, as shown in
The clamping body 50 presented in
In this exemplary embodiment, the spring force may be suitably compensated, may be linearized in relation to the deflection, and/or may be cancelled out completely.
The clamping body does not have to have the form of a general mathematical cylinder. Rather, the clamping body may also have a rotationally symmetrical design, as shown in
In a further exemplary embodiment (not shown specifically), the clamping body results from rotation of the longitudinal section of the clamping body 50. In this case as well, the clamping jaws (not shown specifically) are provided by ball bearings.
In further exemplary embodiments (not shown specifically), which, for the rest, correspond to those described above, the spring elements do not satisfy Hooke's law. Rather, in many cases encountered in practice, the spring constant is not an actual constant, and instead, is dependent on the deflection s. The spring force, therefore, has a non-linear dependency of the spring force F on the deflection s:
F=k(s)*s,
where k(s) describes the spring stiffness now dependent on the deflection. In this case, the clamping body 20 may be configured to compensate for the spring force that follows from this non-linear characteristic or to compensate or weaken the increase/decrease thereof with increasing deflection.
In order to compensate for a non-linear spring force of this kind in the entire deflection range, the form of the clamping body is modified compared to the drawing. If, for example, k(s) increases with the deflection s, the curvature of the clamping body in the non-deflected position thereof is to be lower and is to be higher accordingly at the edge compared to that shown in
The elements and features recited in the appended claims may be combined in different ways to produce new claims that likewise fall within the scope of the present invention. Thus, whereas the dependent claims appended below depend from only a single independent or dependent claim, it is to be understood that these dependent claims may, alternatively, be made to depend in the alternative from any preceding or following claim, whether independent or dependent. Such new combinations are to be understood as forming a part of the present specification.
While the present invention has been described above by reference to various embodiments, it should be understood that many changes and modifications can be made to the described embodiments. It is therefore intended that the foregoing description be regarded as illustrative rather than limiting, and that it be understood that all equivalents and/or combinations of embodiments are intended to be included in this description.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2015 218 851.5 | Sep 2015 | DE | national |
This application is the National Stage of International Application No. PCT/EP2016/073135, filed Sep. 28, 2016, which claims the benefit of German Patent Application No. 10 2015 218 851.5, filed Sep. 30, 2015. The entire contents of these documents are hereby incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2016/073135 | 9/28/2016 | WO | 00 |
