Leaf spring

Abstract

The invention relates to a disk spring (1) formed from a substantially circular, plate-like spring steel sheet (10), wherein the spring steel sheet (10) integrally forms a plurality of spirally bent spring arms (20) of variable width (B) which extend around a center (Z).

Description

[0001] leaf spring

[0002] Description:

[0003] The invention relates to a leaf spring or disc spring with an optimized design, in particular a leaf spring or disc spring for applications in measuring devices or sensors in the automotive industry.

[0004] A variety of different leaf springs are known from the state of the art. Disc springs or leaf springs are particularly well-known for resetting diaphragms or other movable devices in measuring devices.

[0005] DE 10 2008 025 045 A1 discloses such measuring devices comprising a housing and a diaphragm arranged in and / or on the housing. The housing also contains an elastic element for resetting the diaphragm. A signal transmitter is operatively connected to the diaphragm and / or the elastic element. A signal sensor interacts with the signal transmitter to generate the measurement signal. These sensors exhibit a certain hysteresis when the pressure and / or temperature of the fluid being measured changes, which in turn can lead to a falsification of the measurement signal.

[0006] DE 689 08 697 T2 describes a disc spring serving as an elastic restoring element. The disc spring has a spiral-like wave ring structure between its center and its edge.

[0007] DE 10 2010 0022428 A1 discloses a leaf spring for a measuring device with an elastic element. The elastic element has a stiffening structure. In other words, structures are incorporated into the geometry of the elastic element in certain areas to stiffen it. This discloses a space-saving and low-hysteresis spring-membrane system. To reduce the installation height or the installation space, this document proposes designing the elastic element in the manner of a disc-shaped leaf spring. The leaf spring shown expediently has a circular shape. A particularly high restoring force can be achieved with the elastic element if the leaf spring has a spring element that runs spirally from the center to the edge region of the leaf spring. This ensures a compact design with high spring force.

[0008] To reduce the installation height of the measuring device, it was further proposed that, in addition to its circular shape, the leaf spring have a spring element extending spirally from the center to the edge of the leaf spring to achieve a high restoring force. This ensures a compact design with high spring force. It has been shown that, using the solutions known in the prior art, it is difficult to realize a spring with a specific and optimized force-displacement characteristic within the available installation space and material parameters. The known solutions require comparatively large installation space and offer insufficient adaptation options to the desired spring characteristics.

[0009] The invention is therefore based on the object of overcoming the aforementioned disadvantages and providing an optimized solution for a leaf spring or disc spring.

[0010] This problem is solved by the combination of features according to patent claim 1.

[0011] According to the invention, a disc spring (leaf spring) formed from a substantially circular, plate-shaped spring sheet is therefore proposed, wherein the spring sheet forms a plurality of spirally bent spring arms with a variable width B, which extend around a center (middle).

[0012] A preferred solution is one in which the curved spring arms extend over an arc angle a of between 120° and 310°, preferably between 180° and 270°, and more preferably between 200° and 240°. By selecting the angle and width of the spring arms, as well as varying the width of the spring arms along their arcuate extension, the spring characteristics of the disc spring can be adjusted as desired.

[0013] Due to the inventive design of the spring arms, the following properties in particular can be influenced: - Stress reduction in the component and thus increase in component efficiency (especially with a reduction of the width by approximately 25% in the center of the spring arm)

[0014] - Due to the optimized design and the stress reduction, it is possible to achieve the desired spring characteristics with a reduced size (smaller radius).

[0015] In a preferred embodiment of the invention, it is provided that the width B of one, several or preferably all spring arms increases and / or decreases along the arc angle a, at least in sections or over the entire length.

[0016] A design has proven particularly advantageous in which the width B of one, several, or all spring arms initially decreases in sections along their arc angle a and then increases again in sections, preferably having the same width B at the beginning and end. It is also advantageous if the respective spring arm has its minimum width B approximately midway between its two spring arm ends. Advantageous width ratios are explained below in connection with the description of preferred embodiments.

[0017] In a further preferred embodiment of the invention, both ends of the respective spring arms are connected integrally and in one piece to the spring plate. In other words, the spring arms do not have a free end, but are connected or integrally connected to the spring plate at their ends.

[0018] It is advantageous if, viewed in the radial direction R, a correspondingly arcuate gap runs over the entire length of the respective curved spring arms between the respective spring arms. In a likewise preferred embodiment of the invention, it is provided that the spring arms extend at least partially or completely along an Archimedean spiral or a spiral with increasing radius R, so that the radius increases outwards as viewed in the circumferential direction. A further advantageous solution is one in which the spring arms, viewed from the inside outwards in the radial direction R, each have an increasingly larger radius compared to the respective spiral-shaped spring arm located further inside.

[0019] An advantageous embodiment is one in which the spring arms are not mounted within the entire surface of the spring plate, but rather an essentially (approximately) circular spring plate section is present in the center of the plate spring, on which the radially further inner ends of the spring arms are arranged, preferably at an equidistant arc angle.

[0020] A design in which the inner ends of the (in this case, three) spring arms are offset from each other at an arc angle of 120° has also proven advantageous. This means that the three spring arms are nested within each other, each offset by an angle of 120°.

[0021] The arched gap provided between the spring arms advantageously has an increasing width at its beginning and / or end, with a nose-like shape. This end shape can be designed as a nose, teardrop, or pear-shaped.

[0022] In a preferred embodiment, the maximum width B of the spring arms is approximately 2-4% of the spring arm length, but can also deviate from these dimensions if specific properties of the spring plate are to be specifically modified. The width B of the spring arms preferably varies within a range between 20-30%, preferably approximately 25%.

[0023] The features disclosed above can be combined as desired, as long as this is technically possible and they do not contradict each other.

[0024] Other advantageous developments of the invention are characterized in the subclaims or are presented in more detail below together with the description of the preferred embodiment of the invention with reference to the figures.

[0025] They show:

[0026] Fig. 1 is a plan view of a first example of a disc spring according to the invention,

[0027] Fig. 2 is a plan view of an alternative embodiment of a disc spring according to the invention,

[0028] Fig. 3 is a graph showing the relationship between the width reduction of the spring arms and the stress reduction and component size.

[0029] The figures are schematic examples. Identical reference numerals in the figures indicate identical functional and / or structural features.

[0030] Figures 1 and 2 show exemplary embodiments of a disc spring 1. These disc springs 1 consist of a substantially circular, plate-shaped spring plate 10. As can be seen, the spring plate 10 each has three spirally curved spring arms 20. The spring arms 20 have a first spring arm end 20a (inside) and a second spring arm end 20b (radially further outwards). The width B of the spring arms 20 is not constant; rather, the width B of one initially decreases along the arc angle a (here from 0.8 mm) to a dimension of 0.6 mm and then increases again in sections to the dimension of 0.8 mm. The respective spring arm 20 has its minimum width B (0.6 mm) approximately halfway between its two spring arm ends 20a, 20b. The two spring arm ends 20a, 20b of the respective spring arms 20 are integrally and integrally connected to the spring plate 10. This can be achieved by punching out the spring plate, creating the gap 30.

[0031] The curved spring arms 20 extend over a total arc angle of approximately 270°.

[0032] Furthermore, Figures 1 and 2 show that the spring arms 20 extend along a spiral with increasing radius R, which may be an Archimedean spiral. In any case, the three spring arms 20, viewed from the inside outward in the radial direction R, each have an increasingly larger radius than the spiral-shaped spring arm 20 located further inside.

[0033] Centrally, the disc spring 1 has a substantially circular spring plate section 11 on which the radially inner ends 20a of the spring arms 20 are arranged at an equidistant arc angle of 120°.

[0034] The maximum width B of the spring arms 20, approximately 0.8 mm, is approximately 3% of the spring arm length of 26.74 mm. These dimensions are only examples and can be specified differently.

[0035] Below is a Table 1 in conjunction with Figure 3, which explains the change in tension (mechanical stress) to the modification of the width B in the spring arm center.

[0036] Table 1

[0037] In Table 1 and Figure 3, the width B of the spring arms is varied from 0% to 50% in the center, which corresponds to 0.8 mm at each end and from 0.8 mm to 0.4 mm in the center. It is clearly visible that with a 25% reduction in the spring arm width toward the center of the spring arm 20, the stress reduction is maximum at 8.9%. With this configuration, the outer radius can be reduced by 3.8%.

[0038] The invention is not limited in its implementation to the preferred embodiments described above. Rather, a number of variants are conceivable that utilize the presented solution even in fundamentally different configurations. Thus, the invention also relates to a measuring device comprising a disc spring according to the invention as described above.

Claims

Disc spring (1) formed from a substantially circular, plate-shaped spring plate (10), wherein the spring plate (10) integrally forms a plurality of spirally bent spring arms (20) with a variable width B, which extend around a center (Z). Disc spring (1) according to claim 1, characterized in that the bent spring arms (20) extend over an arc angle α which is between 120° and 310°, preferably between 180° and 270°, more preferably between 200° and 240°. Disc spring (1) according to claim 1 or 2, characterized in that the width B of one, several or all spring arms (20) increases and / or decreases along the arc angle α, at least in sections or over the entire length.Disc spring (1) according to claim 1 or 2, characterized in that the width B of one, several or all spring arms (20) initially decreases in sections along the arc angle α and then increases again in sections and preferably has the same width B at the beginning and end. Disc spring (1) according to claim 1, characterized in that the respective spring arm (20) has its minimum width B approximately in the middle between its two spring arm ends (20a, 20b). Disc spring (1) according to one of the preceding claims, characterized in that the two ends (20a, 20b) of the respective spring arms (20) are each connected integrally and in one piece to the spring plate (10).

7. Disc spring (1) according to one of the preceding claims, characterized in that between the respective spring arms (20) viewed in the radial direction R there is a correspondingly arcuate gap (30) over the entire length of the curved spring arms (20).

8. Disc spring (1) according to one of the preceding claims, characterized in that the spring arms (20) extend at least partially or completely along an Archimedean spiral or a spiral with increasing radius R.

9. Disc spring (1) according to one of the preceding claims, characterized in that the spring arms (20), viewed from the inside outwards in the radial direction R, each have an increasingly larger radius compared to the respective further inside, spirally shaped spring arm (20).

10. Disc spring (1) according to one of the preceding claims, characterized in that in the center of the disc spring (1) there is a substantially circular spring plate section (11) on which the radially further inner ends of the spring arms (20) are arranged, preferably at an equidistant arc angle.

11. Disc spring (1) according to one of the preceding claims, characterized in that the respective inner end (20a) of the spring arms (20) are arranged offset from one another at an arc angle of 120°.

12. Disc spring (1) according to one of the preceding claims, characterized in that the respective arcuate gap (30) provided between the spring arms (20) has an increasing width with a nose-like shape at its beginning and / or end. Disc spring (1) according to one of the preceding claims, characterized in that the maximum width B of the spring arms (20) is approximately 2-4% of the spring arm length. Disc spring (1) according to one of the preceding claims, characterized in that the width B of the spring arms (20) varies within a range between 20-30%, preferably approximately 25%. Measuring device comprising a disc spring (1) according to one of the preceding claims.

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