DE102010008194A1 - Adaptive spring element for use in magnetic actuator in e.g. pneumatic valve, has spring whose walls comprise recesses, where length and/or rigidity of element is adjusted by number of recesses bridged with control element - Google Patents

Abstract

The element has a tubular spring (1) whose walls comprise axially stepped concentric recesses, where the spring exhibits a hollow cylindrical, hollow prism or cone shape. An actuated interconnection is provided at two ends of the tubular spring and a control element (2). Length and/or rigidity of the element are adjusted by number of recesses in the spring bridged with the control element. The tubular spring and the control element comprise an external thread and an internal thread, respectively. The recesses exhibit elongated shape with edging or tilting contour.

Description

The present invention relates to an adaptive spring element which z. B. in magnetic (resonance) actuators, which act as a driving element in pneumatic and hydraulic valves, can be used. In addition, the spring element according to the invention could be used for adjustable support (i.e., force absorption) of beams and plates to minimize their deflection or to increase their natural frequency or to detune the characteristic shapes of beams and plates. As a technical application example, a plate which deflects due to gravity is conceivable (for example in a machine frame), which can be supported forcibly with the aid of an adaptive spring element according to the invention.

A spring or spring element is referred to in the specialist literature as an elastic component which yields under load (ie, deforms) and returns to its original shape upon release. For springs exist many different designs, eg. B. diaphragm springs, disc spring stack, Wellfederstapel, various coil springs or coil springs. On the one hand, springs serve as an energy store (potential energy) or for applying a defined force, since there is always a mathematical relationship between the deflection of the spring and the restoring force it exerts. Furthermore, springs and spring assemblies are also known for guiding (i.e., receiving forces and moments perpendicular to and moments about the axis of motion of components being employed, their stiffness being less than perpendicular thereto in the direction of motion.

Diaphragm springs are for use as a guide element, so to be able to absorb moments perpendicular to the central axis, at least in pairs and allow compared to the outer diameter only small inner diameter. There is a mathematical relationship between possible deflection and the outer / inner diameter ratio: they behave proportionally to each other. Disc spring and Wellfederstapel often consist of metallic, mostly ferrous materials and are therefore u. U. for applications in the field of influence of magnetic fields, for example, in or near electromagnetic actuators, not suitable. They can not pick up moments around the center axis and have a small ratio of inside to outside diameter. Coil springs twist during axial deformation and are not suitable for guiding components. They also consist mostly of metallic, iron-containing materials and are therefore for applications in the field of influence of magnetic fields u. U. not suitable. Furthermore, they can absorb only small or only to a limited extent moments about the central axis. Bourdon tubes can absorb moments along their central axis and therefore simultaneously act as a shaft. With regard to the choice of materials, they are particularly variable, so that they can be used in a broader field of application also because of their magnetic, thermal, electrical etc. properties, while the choice of material in other types of spring is already severely limited by the required spring properties. Further advantages of the bourdon tubes are based on the fact that, in contrast to, for example, coil springs, their spring ends do not rotate with one another when the spring is deflected. In addition, the support line (or the support points) does not shift with a deflection in the radial direction (in contrast to disc springs). A Bourdon tube can absorb high transverse forces perpendicular to the central axis with comparatively small deflections in the direction of force application and can therefore also be used as a guide element.

Various tube springs are already known from the prior art. So describes z. B. the EP 1 519 072 B1 Such a resilient element with annular cross-section, wherein different geometries of the recesses are provided, which are arranged in several rows one above the other. The structure is produced by punching. The EP 1 434 952 B1 also describes a resilient element with an annular cross section, in which the distances of the recesses are in a certain ratio to the wall thickness. The production of these compliant elements is carried out by means of jet cutting processes (eg laser or water jet cutting). With the DE 10 2005 046 269 B4 a bourdon tube spring for biasing a piezoelectric or magnetostrictive actuator is presented, which is produced in an injection molding of metal or ceramic, wherein the recesses in the wood cylinder produced directly by injection molding. In the in the DE 10 2006 035 038 A1 described spring element for biasing a piezoelectric actuator provided in the spring element recesses are each formed as a polygon with rounded corners.

Finally, out of the DE 879 327 B a cylindrical Bourdon tube known whose effective length (ie, their rigidity) can be adjusted via a sliding nut, the total length of the spring remains constant. However, this Bourdon tube is designed as a helical spring. Therefore, their two ends twist in a deflection to each other, which changes the orientation of the spring itself and possibly coupled components in addition to the position. This creates friction on the support surface or line or at the support points, the In the form of wear adversely affect the components of the friction pairing as well as the leadership properties of the spring.

The known from the prior art solutions also have the disadvantage that their spring rate (increase in the force-displacement curve) and the course of the spring characteristic (degressive, linear, progressive) are not adjustable or invariable.

The object of the present invention is therefore to overcome the disadvantages of the prior art and to provide an adaptive spring element in which the inner to outer diameter ratio allows a passage or implementation of further components and / or fluidic media and generates a restoring force and lateral forces and moments can be absorbed perpendicular to the central axis, without introducing a moment about the central axis.

According to the invention, the solution of this problem succeeds with the features of the first claim.

Preferred further embodiments of the spring element according to the invention are specified in the subclaims.

The invention will be explained in more detail below with reference to drawings. Show it:

1 - Two embodiments of a tubular spring in perspective view

2 - Two embodiments of a tubular spring in a sectional view

3 - Embodiments of the edge and edge contours of the recesses in a Bourdon tube

4 - Various embodiments of the spring element according to the invention

The adaptive spring element according to the invention comprises at least one Bourdon tube ( 1 ) and at least one actuator ( 2 ). Two embodiments of such a Bourdon tube are in 1 in perspective and in 2 shown cut. The bourdon tube ( 1 ) a cylindrical ( 1a and 2a ), a prismatic ( 1b and 2 B ) or a cone (blunt) shaped (not shown) component with internal, concentric or non-concentric, prismatic or cylindrical recess (continuous or sectioned), are introduced into the axially stepped concentric recesses. The number, size, shape and position of the recesses and grading is arbitrary. The Bourdon tube can be embodied in any materials, can be monolithic or heterogeneous, and can follow a straight or non-straight geometry (for example, obliquely or along an extrusion path). The shape and the number of axially stepped concentric recesses are arbitrary ( 3 ). Both the recess angle (for cylindrical versions) and the recess width (for prismatic versions) as well as the height of the recess can be changed so that all recesses of the Bourdon tube or all recesses of a stage or no recess in a (arbitrary) stage the same height or has the same recess angle. The contour of the recesses, in particular the transition between the recess surfaces (hereinafter referred to as edge contour) can take any shape and be different at each recess and at each circular arc edge of a recess. The cutout surfaces defining the recesses may be flat or curved, parallel or non-parallel to each other. The edge contour of the development of the cutout can be linear, any function curve or composed of several arbitrary function curves. The connection between an upper and an associated lower edge of the development of the recess surface can be generated by any continuous or non-continuous curves or composite curves. The clear dimension of the edge contour can exceed that of the recess in staging direction.

In 4 different embodiments of the spring element according to the invention are shown. In this case, one or more coil springs ( 1 ) together ( 4a and 4c ) or with one or more control elements ( 2 ) ( 4b . 4d . 4e and 4f ) via external or internal thread for adjusting the stiffness of the spring element combined with each other, wherein the rigidity of the individual components of the spring element may well be different.

In 4a a first embodiment of the spring element according to the invention is shown, in which two first and third bourdon tube are each connected to each other via threads. By screwing the third tube spring in or on one or two first tube springs, possibly other stiffness, the recesses in the tube springs can be partially bridged and the stiffness of the spring element can be changed. It goes without saying that it is within the scope of the invention that the first two tube springs can have the same or a different rigidity.

A second embodiment of a spring element according to the invention using two coil springs is in 4b shown. By screwing in a rigid actuator ( 2 ) can also check the stiffness and length of the Be changed spring element. The coil springs can also be different in shape and diameter here. Instead of a rigid inner control element and a rigid ring (outer actuator) is suitable for adjusting the stiffness and length of the spring element.

In 4c a third embodiment of an adaptive spring element according to the invention with two tube springs is shown. By screwing or screwing a Bourdon tube into or onto another Bourdon tube of the same or different stiffness, the cutouts in the Bourdon tubes are partially bridged and the rigidity and the length of the entire spring element are changed.

In 4d and 4e Further embodiments of the adaptive spring element according to the invention are shown. By screwing on or screwing in a rigid actuating element ( 2 ) on or in the Bourdon tube ( 1 ), the recesses in the Bourdon tube ( 1 ) partially bridged and changed the stiffness and length of the spring element so.

The spring element according to the invention is in addition to the function of energy storage in a position to absorb moments about each major axis and forces orthogonal to the central axis and generates a restoring force in the axial direction. When rotated about the central axis also a restoring torque is generated. By appropriate design of the spring element, for example, a non-symmetrical structure, it is possible to influence these properties (restoring forces and moments) for the individual axes differently. Due to these properties, the spring element is able to assume leadership functions. With it, both a length-invariant stiffness change and a stiffness-invariant change in length as well as the simultaneous change of length and stiffness can be realized.

It is also within the scope of the invention that the shape of the spring element according to the invention not only includes tubes (hollow cylinder) with recesses, but also hollow prisms and truncated cones, each in a straight or slated embodiment. In this case, in order to realize the adaptivity, the thread (in contrast to the embodiments shown in the figures) must be cut on the outside of the blank. Alternatively, the adaptivity can also be realized by inserts (spacers), which are inserted from the inside or outside into the recesses. Alternatively, suitable form elements (eg cones) can be attached to the ends of the spring, which at a certain deformation of the spring enter into a surface pairing with the spring and thereby stiffen them massively in the direction of higher forces.

The adaptive spring element according to the invention can also be embodied in non-ferromagnetic materials (eg spring bronze). For the fabrication of the structure and the recesses, primary shaping methods, for example MIM (metal injection molding) technologies or injection molding are just as suitable as ablative methods such as etching, eroding, machining (also in each case in conjunction with lithographic methods) or combinations thereof. Depending on the technological boundary conditions and the material chosen, spring elements with different spring stiffnesses, restoring and guiding properties that can be adapted to the respective application are possible with identical main dimensions.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1519072 B1 [0004]
• EP 1434952 B1 [0004]
• DE 102005046269 B4 [0004]
• DE 102006035038 A1 [0004]
• DE 879327 B [0005]

Claims (9)

Adaptive spring element which has at least one Bourdon tube ( 1 ), whose wall has axially stepped concentric recesses, and at least one actuating element ( 2 ) and a hollow cylinder or hollow prismatic shape, characterized in that the at least one Bourdon tube ( 1 ) and the at least one actuating element ( 2 ) at least at their first and / or second ends each having means for positive and / or non-positive mutual connection and the length and / or rigidity of the spring element by the number of at least one actuating element ( 2 ) bridged recesses in the at least one Bourdon tube ( 1 ) is adjustable. Adaptive spring element according to claim 1, characterized in that the actuating element ( 2 ) is designed as a tube spring. Adaptive spring element according to claim 1, characterized in that the actuating element ( 2 ) is rigid. Adaptive spring element according to one of claims 1 to 3, characterized in that the at least one Bourdon tube ( 1 ) External thread and the actuator ( 2 ) Have internal thread. Adaptive spring element according to one of claims 1 to 3, characterized in that the at least one Bourdon tube ( 1 ) Female thread and the actuator ( 2 ) Have external thread. Adaptive spring element according to one of claims 1 to 5, characterized in that it consists of several coil springs ( 1 ) of equal and / or different stiffness and one or more actuating elements ( 2 ) consists. Adaptive spring element according to one of claims 1 to 6, characterized in that the recesses have an elongated shape with any edge and edge contour. Adaptive spring element according to one of claims 1 to 7, characterized in that it is constructed asymmetrically. Adaptive spring element according to one of claims 1 to 8, characterized in that the Bourdon tube and the adjusting element are produced by means of injection molding.

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