Nut press-fit structure

Abstract

To provide a nut press-fitting structure which can properly dispose shavings occurring during press-fitting.SOLUTION: A nut press-fitting structure 1 includes: a nut 10; and a housing 20 having a press-fitting recessed part 21 into which the nut 10 may be press-fitted. The press-fitting recessed part 21 has: a first opening 21a which is open along a press-fitting direction X of the nut 10; a second opening 21b which is open along a direction Z intersecting with the press-fitting direction X; and a plurality of ribs 22 formed along the press-fitting direction X on a first inner wall surface 21c, which is located adjacent to the first opening 21a and the second opening 21b, and interposed between the first inner wall surface 21c and the nut 10. The plurality of ribs 22 includes: a first rib 23 which is formed having a relatively large protruding amount L1 from the first inner wall surface 21c; and a second rib 24 which is provided between the first rib 23 and the second opening 21b and formed having a relatively small protruding amount L2 from the first inner wall surface 21c.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a nut press-fitting structure.

Background Art

[0002] For example, Patent Document 1 discloses a nut press-fitting structure including a nut and a housing having a recess (press-fitting recess) into which the nut can be press-fitted, and the nut is held by ribs formed on the inner wall surface of the press-fitting recess.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the nut press-fitting structure described in the above Patent Document 1, when the nut is press-fitted into the press-fitting recess, the nut contacts the ribs, and the ribs may be scraped by the nut, resulting in the generation of chips. There is room for further improvement in terms of the treatment of these chips.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a nut press-fitting structure capable of properly treating chips generated during press-fitting.

[0006] To achieve the above objective, the nut press-fitting structure according to the present invention comprises a nut on which a fastening member is fastened with a conductive member interposed between the fastening member and the nut, and a housing having a press-fitting recess into which the nut can be press-fitted, wherein the press-fitting recess has a first opening that opens along the press-fitting direction of the nut, a second opening that opens along a direction intersecting the press-fitting direction, and a plurality of ribs formed along the press-fitting direction on a first inner wall surface located adjacent to the first opening and the second opening, and interposed between the first inner wall surface and the nut, wherein the plurality of ribs include a first rib formed to protrude relatively large from the first inner wall surface, and a second rib provided between the first rib and the second opening, and formed to protrude relatively small from the first inner wall surface.

[0007] The nut press-fitting structure according to the present invention has the effect of properly disposing of the shavings generated during press-fitting. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a perspective view showing the schematic configuration of the nut press-fitting structure according to the embodiment. [Figure 2] Figure 2 is an exploded perspective view showing the schematic configuration of the nut press-fitting structure according to the embodiment. [Figure 3] Figure 3 is a partial perspective view showing the state of the nut press-fitting structure according to the embodiment before the nut is pressed in. [Figure 4] Figure 4 is a partial plan view showing the state of the nut press-fitting structure according to the embodiment before the nut is pressed in. [Figure 5] Figure 5 is a partial perspective view showing the state of the nut press-fitting structure according to the embodiment after the nut has been pressed in. [Figure 6] Figure 6 is a partial plan view showing the state of the nut press-fitting structure according to the embodiment after the nut has been pressed in. [Figure 7] Figure 7 is a partial perspective view showing the schematic configuration of a modified nut press-fitting structure. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is not limited by these embodiments. Furthermore, some of the components in the following embodiments are substituted or substantially identical to those easily substituted by those skilled in the art.

[0010] [Embodiment] The nut press-fitting structure 1 according to this embodiment is applied to a conductive fixing portion 100 that fixes a conductive member 101, as shown in Figures 1 and 2. The conductive fixing portion 100 is the part in which the conductive member 101 is positioned adjacent to the nut 10 that has been press-fitted into the housing 20, and the conductive member 101 is joined and fixed to the nut 10 via a bolt 102.

[0011] The conductive member 101 is a conductive material, such as a terminal or busbar formed in the shape of a plate from a metal material. In Figures 1 and 2, only a part of the conductive member 101 is shown. The conductive member 101 has a bolt insertion hole 101a formed therein. The bolt insertion hole 101a is a hole through which the shaft portion 102a of a bolt 102, which is fastened to a nut 10, is inserted. The bolt 102 is a conductive material, and in this case, it is a fastening member formed from a metal material. The bolt 102 has a threaded groove formed on the outer circumferential surface of the shaft portion 102a, and when combined with the nut 10, it can tighten and fix the conductive member 101 sandwiched between the nut 10 and the bolt 10.

[0012] Figures 1 and 2 illustrate three combinations of nuts 10, conductive members 101, and bolts 102, with one conductive member 101 shown in each combination. In addition, in this conductive fixing part 100, for example, multiple stacked conductive members 101 can be electrically connected and fixed by fastening them together with nuts 10 and bolts 102.

[0013] In the nut press-fit structure 1 applied to such a conductive fixing part 100, the nut 10 is press-fitted into a press-fit recess 21 formed in the housing 20. The housing 20 is provided with a press-fit rib 22 inside the press-fit recess 21, which is provided along the press-fit direction to hold the press-fitted nut 10. In this configuration, the nut press-fit structure 1 of this embodiment is configured such that the press-fit rib 22 is made up of two ribs of different sizes, namely a first rib 23 and a second rib 24, thereby enabling proper disposal of shavings S (see Figure 6) generated when the press-fit rib 22 is worn down when the nut 10 is press-fitted into the press-fit recess 21. The various components of the nut press-fit structure 1 will be described in detail below with reference to Figures 2 to 6.

[0014] For convenience, in the following explanation, the three intersecting directions will be referred to as "first direction X," "second direction Y," and "third direction Z." Here, the first direction X, second direction Y, and third direction Z are orthogonal to each other. The first direction X typically corresponds to the direction in which the nut 10 is pressed into the press-fit recess 21. The second direction Y and third direction Z correspond to directions that intersect the press-fit direction (first direction X). Of these, the second direction Y corresponds to the protruding direction of the press-fit rib 22, and the third direction Z corresponds to the width direction of the press-fit rib 22. Unless otherwise specified, each direction used in the following explanation refers to the direction when the nut 10 is pressed into the press-fit recess 21.

[0015] Specifically, the nut press-fit structure 1 comprises a nut 10 and a housing 20, as shown in Figure 2. As described above, the nut 10 is a member that fastens the fastening member 102 with a conductive member 101 interposed between it and the fastening member 102. As described above, the housing 20 is a member having a press-fit recess 21 into which the nut 10 can be press-fitted.

[0016] The nut 10 is a conductive component, and in this case, it is a square nut made of a metal material. The nut 10 in this embodiment is formed in a substantially rectangular shape when viewed along the third direction Z, and has a bolt fastening hole 10a that penetrates along the third direction Z. The bolt fastening hole 10a is a hole with a screw groove formed on its inner circumferential surface, into which the shaft portion 102a of the bolt 102 is screwed. The nut 10 is press-fitted into the press-fit recess 21 in a positional relationship in which the bolt fastening hole 10a faces the third direction Z.

[0017] The housing 20 is formed, for example, from an insulating synthetic resin material and is a component that holds the nuts 10 housed in the press-fit recesses 21. In Figures 1 and 2, only a portion of the housing 20 is shown. Here, the housing 20 is divided into three parts corresponding to the three nuts 10, with one press-fit recess 21 formed in each part, for a total of three press-fit recesses 21. Here, the three press-fit recesses 21 are positioned spaced apart along the second direction Y.

[0018] As shown in Figures 2 and 3, the press-fit recess 21 is formed at the corner 20C (see Figure 3) on one side of the housing 20 in the first direction X and one side in the third direction Z. Thus, the press-fit recess 21 is formed having a first opening 21a that opens along the first direction X, which is the press-fit direction of the nut 10, and a second opening 21b that opens along the third direction Z, which is the direction intersecting the first direction X. The first direction X, which is the press-fit direction of the nut 10, corresponds to the opening direction of the first opening 21a, and the third direction Z, which intersects the first direction X, corresponds to the opening direction of the second opening 21b.

[0019] More specifically, the press-fitting recess 21 is formed as a substantially rectangular columnar concave space portion having a first opening 21a and a second opening 21b, by a pair of first inner wall surfaces 21c, one second inner wall surface 21d, and one third inner wall surface 21e. The pair of first inner wall surfaces 21c are wall surfaces that partition both sides in the second direction Y in the press-fitting recess 21, and are positioned opposite to each other with an interval along the second direction Y. The second inner wall surface 21d is a wall surface that partitions one side in the third direction Z in the press-fitting recess 21, here, the side opposite to the second opening 21b, and is positioned opposite to the second opening 21b along the third direction Z. The third inner wall surface 21e is a wall surface that partitions one side in the first direction X in the press-fitting recess 21, here, the side opposite to the first opening 21a, and is positioned opposite to the first opening 21a along the first direction X.

[0020] And the pair of first inner wall surfaces 21c are positioned adjacent to the first opening 21a and the second opening 21b, and form a part of the first opening 21a by the edge on the side opposite to the third inner wall surface 21e side in the first direction X, and form a part of the second opening 21b by the edge on the side opposite to the second inner wall surface 21d side in the third direction Z. Similarly, the second inner wall surface 21d is positioned adjacent to the first opening 21a, and forms the remaining part of the first opening 21a by the edge on the side opposite to the third inner wall surface 21e side in the first direction X. The third inner wall surface 21e is positioned adjacent to the second opening 21b, and forms the remaining part of the second opening 21b by the edge on the side opposite to the second inner wall surface 21d side in the third direction Z. That is, the first opening 21a is formed by the edges on one side in the first direction X of the pair of first inner wall surfaces 21c and the second inner wall surface 21d, and the second opening 21b is formed by the edges on one side in the third direction Z of the pair of first inner wall surfaces 21c and the third inner wall surface 21e. Here, the first opening 21a, the second opening 21b, the pair of first inner wall surfaces 21c, the second inner wall surface 21d, and the third inner wall surface 21e are each formed in a substantially rectangular shape, and the press-fitting recess 21 is formed as a substantially rectangular columnar concave space portion surrounded by the first opening 21a, the second opening 21b, the pair of first inner wall surfaces 21c, the second inner wall surface 21d, and the third inner wall surface 21e as described above.

[0021] And, as shown in FIGS. 3, 4, 5, and 6, the press-fitting recess 21 has a plurality of press-fitting ribs 22 formed along the first direction X, which is the press-fitting direction of the nut 10, on the first inner wall surface 21c. Here, a plurality of press-fitting ribs 22 are formed on each of the pair of first inner wall surfaces 21c in each press-fitting recess 21. That is, here, each of the pair of first inner wall surfaces 21c constitutes a rib forming surface on which a plurality of press-fitting ribs 22 are formed. The plurality of press-fitting ribs 22 are respectively interposed between the first inner wall surface 21c and the nut 10 in a state where the nut 10 is press-fitted into the press-fitting recess 21 (see FIGS. 5 and 6).

[0022] And, the plurality of press-fitting ribs 22 of the present embodiment are configured to include a first rib 23 and a second rib 24. Here, the plurality of press-fitting ribs 22 are configured to include one first rib 23 and one second rib 24 on each of the pair of first inner wall surfaces 21c.

[0023] Both the first rib 23 and the second rib 24 are formed to protrude inward of the press-fitting recess 21 along the second direction Y from the first inner wall surface 21c, and as described above, are each formed in a linear columnar shape along the first direction X on the first inner wall surface 21c. Here, the first rib 23 and the second rib 24 are formed substantially parallel to each other along the first direction X.

[0024] Also, in the examples shown in FIGS. 3, 4, 5, and 6, as an example, the first rib 23 is formed as a convex rib having a substantially semi-circular cross-sectional shape when viewed along the first direction X. Similarly, in the examples shown in FIGS. 3, 4, 5, and 6, as an example, the second rib 24 is formed as a convex rib having a substantially semi-circular cross-sectional shape when viewed along the first direction X.

[0025] Furthermore, in the state before the nut 10 is pressed into the press-fit recess 21, the amount of protrusion L1 (see Figure 4) of the first rib 23 from the first inner wall surface 21c along the second direction Y is relatively larger compared to the amount of protrusion L2 (see Figure 4) of the second rib 24. In other words, in the state before the nut 10 is pressed into the press-fit recess 21, the amount of protrusion L2 of the second rib 24 from the first inner wall surface 21c along the second direction Y is relatively smaller compared to the amount of protrusion L1 of the first rib 23.

[0026] Here, the amount of protrusion L1 of the first rib 23 is set to be the amount by which the first rib 23 is plastically deformed and worn down by the nut 10 when the nut 10 is pressed into the press-fit recess 21. In other words, the amount of protrusion L1 of the first rib 23 is set such that the distance between a pair of first ribs 23 facing each other along the second direction Y is smaller than the width of the nut 10 along the second direction Y, so that when the nut 10 is pressed into the press-fit recess 21, the first rib 23 is deformed and worn down by the nut 10.

[0027] On the other hand, the protrusion amount L2 of the second rib 24 is set to be such that when the nut 10 is press-fitted into the press-fit recess 21, it makes zero contact (line contact) with the side surface 10b of the nut 10 (the circumferential surface other than the open end surface of the bolt insertion hole 101a) (see Figures 5, 6, etc.). It is permissible that the second rib 24 may have a very small gap between it and the side surface 10b, or that it may be worn down by the nut 10, depending on the manufacturing tolerance of the protrusion amount L2.

[0028] Furthermore, the first rib 23 is formed with a width W1 (see Figure 4) along the third direction Z that is relatively larger compared to the protrusion amount L2 (see Figure 4) of the second rib 24. In other words, the second rib 24 is formed with a width W2 along the third direction Z that is relatively smaller compared to the width W1 of the first rib 23.

[0029] The second rib 24 is positioned between the first rib 23 and the second opening 21b with respect to the third direction Z. In other words, the first rib 23 is positioned between the second rib 24 and the second inner wall surface 21d with respect to the third direction Z. That is, the first rib 23 is provided in the press-fit recess 21 on the side of the second inner wall surface 21d in the third direction Z, and the second rib 24 is provided in the press-fit recess 21 on the side of the second opening 21b in the third direction Z. Here, the first rib 23 and the second rib 24 are positioned with a gap D (see Figure 4) with respect to the third direction Z.

[0030] The first rib 23, configured as described above, can function as a crushing rib that guides the nut 10 along the first direction X when the nut 10 is pressed into the press-fit recess 21, and is plastically deformed and worn down by the nut 10. As a result, the first rib 23 can function as the main part that generates frictional force to hold the nut 10, which has been pressed into the press-fit recess 21, within the press-fit recess 21.

[0031] Here, when the nut 10 is press-fitted into the press-fit recess 21, the protruding top 23a of the first rib 23 is scraped away, and the scraped portion is exposed as a new surface, forming a flat portion 23b (see Figures 5 and 6). The flat portion 23b of the first rib 23 then forms the contact surface with the side surface 10b of the nut 10. In other words, after the nut 10 has been press-fitted into the press-fit recess 21, the first rib 23 has a flat portion 23b formed on the protruding top 23a of the first rib 23 that contacts the side surface 10b of the nut 10 and holds it in the press-fit recess 21 by frictional force. This flat portion 23b is formed to have an area that can generate a frictional force (holding force) of a size sufficient to hold the nut 10 in the press-fit recess 21 at the contact surface with the side surface 10b of the nut 10. In other words, the width W1 of the first rib 23 is set to account for the amount that will be removed by the nut 10, so that the flat portion 23b has the above area.

[0032] On the other hand, the second rib 24, configured as described above, can guide the nut 10 along the first direction X when the nut 10 is pressed into the press-fit recess 21, and can also function as an auxiliary rib to prevent the shavings S generated when the first rib 23 is scraped when the nut 10 is pressed into the press-fit recess 21 from spilling out from the second opening 21b side.

[0033] In this embodiment, the press-fit recess 21 has a storage portion 25 capable of accommodating shavings S due to the blocking function of the second rib 24. This storage portion 25 is formed by the space GP located between the second inner wall surface 21d, which is located opposite the second opening 21b, and the first rib 23, and between the first rib 23 and the second rib 24. This storage portion 25 is formed to have a volume equal to or greater than the volume of shavings S generated when the first rib 23 is worn down when the nut 10 is press-fitted into the press-fit recess 21; in this case, a volume capable of accommodating all of the shavings S. In other words, the second rib 24 is positioned such that the distance D (see Figure 4) between it and the first rib 23 along the second direction Y is set so that the storage portion 25 can have the above volume.

[0034] Furthermore, if the second rib 24 is slightly worn down during the press-fitting of the nut 10, it will partially assist the first rib 23 in holding the nut 10 in place. However, the amount of shavings S generated when the second rib 24 is worn down during the press-fitting recess 21 of the nut 10 is minimal.

[0035] In the nut press-fitting structure 1 configured as described above, for example, with the housing 20 set on a jig or the like, the nut 10 is press-fitted into the press-fitting recess 21 from the first opening 21a along the first direction X, with the bolt fastening hole 10a of the nut 10 facing the second opening 21b side of the press-fitting recess 21. At this time, the nut press-fitting structure 1 guides the press-fitting of the nut 10 along the first direction X with the first rib 23 and the second rib 24, and the nut 10 is press-fitted while the side surface 10b of the nut 10 grinds down the first rib 23. At this time, the shavings S generated when the first rib 23 is ground down are prevented from spilling out from the second opening 21b side by the second rib 24 and are contained in the housing portion 25 formed in the press-fitting recess 21.

[0036] Then, the nut press-fitting structure 1 completes the press-fitting of the nut 10 into the press-fitting recess 21 when the nut 10 is pushed in until it contacts the third inner wall surface 21e. In this state, the nut press-fitting structure 1 uses the frictional force generated at the contact surface between the flat portion 23b formed by grinding down the protruding top portion 23a of the first rib 23 and the side surface 10b of the nut 10 as a holding force to hold the nut 10 that has been press-fitted into the press-fitting recess 21. Subsequently, in the conductive fixing part 100, the conductive member 101 and the bolt 102 are assembled to the nut 10 that has been press-fitted into and held in the press-fitting recess 21, thereby joining and fixing the conductive member 101 to the nut 10 via the bolt 102.

[0037] The nut press-fitting structure 1 described above can press-fit and hold a nut 10, to which the fastening member 102 is fastened with a conductive member 101 interposed between the bolt 102 and the nut 10, into the press-fitting recess 21 of the housing 20. In this case, when the nut 10 is press-fitted into the press-fitting recess 21 from the first opening 21a along the first direction X, the nut 10 is pressed in while scraping the first rib 23, and the nut 10 pressed into the press-fitting recess 21 can be held in the press-fitting recess 21 by the frictional force generated at the contact surface between the first rib 23 and the nut 10. At this time, the nut press-fitting structure 1 can prevent the scraping debris S generated by scraping the first rib 23 from spilling out from the second opening 21b side, for example, from falling to the outside of the housing 20, by blocking it with the second rib 24. As a result, the nut press-fitting structure 1 can properly process the shavings S generated when the press-fitting rib 22 is scraped when the nut 10 is press-fitted into the press-fitting recess 21.

[0038] In this case, the nut press-fitting structure 1 described above can contain the shavings S that are blocked by the second rib 24 in the storage section 25 formed as a space GP between the second inner wall surface 21d and the first rib 23, or between the first rib 23 and the second rib 24. Therefore, it is possible to more reliably prevent the shavings from falling to the outside of the housing 20 as described above and to dispose of them properly.

[0039] More specifically, the nut press-fitting structure 1 described above can hold the nut 10 in the press-fitting recess 21 by the flat portion 23b formed on the protruding top 23a of the first rib 23 as the nut 10 is pressed into the press-fitting recess 21. Furthermore, the nut press-fitting structure 1 can properly dispose of the shavings S generated when the nut 10 is used to form the flat portion 23b on the protruding top 23a of the first rib 23, as described above.

[0040] Furthermore, in the nut press-fitting structure 1 described above, the width W2 of the second rib 24 along the third direction Z is formed to be smaller than the width W1 of the first rib 23 along the third direction Z. Therefore, the second rib 24 can be kept to the minimum necessary size, suppressing its enlargement, and the shavings S can be properly processed as described above.

[0041] Furthermore, the nut press-fitting structure according to the embodiments of the present invention described above is not limited to the embodiments described above, and various modifications are possible within the scope of the claims.

[0042] In the above description, it has been explained that each of the pair of first inner wall surfaces 21c constitutes a rib-forming surface on which a plurality of press-fit ribs 22 are formed, and that each of the plurality of press-fit ribs 22 includes one first rib 23 and one second rib 24 on each of the pair of first inner wall surfaces 21c, but the description is not limited to this. The first rib 23 and the second rib 24 only need to be formed on at least one of the pair of first inner wall surfaces 21c, and multiple ribs of each may be formed.

[0043] In the above explanation, the first rib 23 and the second rib 24 were described as being formed substantially parallel to the first direction X, but this is not the only way. The first rib 23 and the second rib 24 only need to be formed extending along the first direction X, which is the press-fit direction, and for example, they may each be slightly inclined with respect to the first direction X.

[0044] In the above description, the first rib 23 and the second rib 24 are described as being formed as convex ribs with a cross-sectional shape that is approximately semicircular when viewed along the first direction X, but the invention is not limited to this. Figure 7 is a diagram showing an example of a modified press-fit rib 22A. The multiple press-fit ribs 22A shown in Figure 7 are composed of a first rib 23A and a second rib 24A. The press-fit ribs 22A, first rib 23A and second rib 24A shown in Figure 7 differ from the embodiments described above in terms of shape. The other configurations of the press-fit ribs 22A, first rib 23A and second rib 24A in the modified examples are substantially the same as those of the embodiments described above. The first rib 23A and second rib 24A in these modified examples are both formed as convex ribs with a cross-sectional shape that is approximately triangular when viewed along the first direction X. The approximately triangular shape may be any shape, such as an equilateral triangle, isosceles triangle, or right triangle. Even when the press-fit ribs 22A, first rib 23A, and second rib 24A shown in Figure 7 are applied, the nut press-fit structure 1 can properly process the shavings S generated when the press-fit rib 22A is shaved down when the nut 10 is press-fitted into the press-fit recess 21, similar to the embodiment described above.

[0045] The nut press-fit structure according to this embodiment may be constructed by appropriately combining the components of the embodiments and modified examples described above. In Figure 2, the set on the left shows the press-fit rib 22, first rib 23, and second rib 24 shown in Figure 3, etc., while the two sets in the center and on the right show the press-fit rib 22A, first rib 23A, and second rib 24A shown in Figure 7. [Explanation of Symbols]

[0046] 1. Nut press-fit structure 10 nuts 10a Bolt fastening hole 10b side 20 Housing 21 Press-fit recess 21a 1st opening 21b 2nd opening 21c 1st inner wall surface 21d Second inner wall surface 21e Third inner wall surface 22, 22A Press-fit ribs 23, 23A First Rib 23a Protruding top 23b Plane part 24, 24A Second Rib 25 Storage Unit 101 Conductive member 102 Bolts (fastening members) D interval GP space section L1, L2 protrusion amount S Shavings W1, W2 width X First direction (press-fit direction) Y Second direction Z Third direction (direction intersecting the press-fit direction)

Claims

1. A nut on which a fastening member is fastened, with a conductive member interposed between the fastening member and the nut, The housing comprises a press-fit recess into which the nut can be press-fitted, The press-fit recess has a first opening that opens along the press-fit direction of the nut, A second opening that opens along a direction intersecting the press-fitting direction, The first inner wall surface located adjacent to the first opening and the second opening is formed along the press-fitting direction, and has a plurality of ribs interposed between the first inner wall surface and the nut, The plurality of ribs are characterized in that they include a first rib formed to protrude relatively large from the first inner wall surface, and a second rib provided between the first rib and the second opening, and formed to protrude relatively small from the first inner wall surface. Nut press-fit structure.

2. The first rib and the second rib are positioned at intervals with respect to a direction intersecting the press-fit direction. The press-fit recess is formed by the space between the second inner wall surface located opposite the second opening and the first rib, and the space between the first rib and the second rib, and has a storage portion capable of accommodating shavings generated when the nut cuts against the first rib during press-fitting. The nut press-fitting structure according to claim 1.

3. The first rib has a flat portion formed at the top of the first rib that contacts the nut, The nut press-fitting structure according to claim 1 or claim 2.

4. The second rib is formed such that its width along the direction intersecting the press-fitting direction is smaller than the width of the first rib along the direction intersecting the press-fitting direction. The nut press-fitting structure according to claim 1 or claim 2.

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