In the prior art, the coils of a retaining spring are located with the help of a two-part riveted connection in an open-edged recess of a brake pad backing plate. To assemble the retaining spring to the backing plate, the retaining spring with its coils is set on a substantially cylindrical rivet body and secured in the open-edged recess of the backing plate with the aid of a rivet counterpiece. This construction is complicated and expensive.

The object of the present invention is, therefore, to continue development of an anchoring arrangement between a brake pad backing plate and a retaining spring such that the anchoring arrangement can be manufactured more simply and more economically.

This object is achieved with an anchoring arrangement of the type stated at the beginning, whereby a shoulder-like section projecting radially inward into the recess is provided in the recess, grasped at least in sections by adjacent coils of the retaining spring.

As a result of the anchoring arrangement in accordance with the invention, the riveted connection from the prior art can be eliminated, since the retaining spring with its adjacent coils is accommodated in the recess of the backing plate, wherein adjacent coils grasp the shoulder- like section on both sides. Since the brake pad backing plate can be configured, for example, as a pressed or forged part, the shoulder-shaped section can be produced without additional cost. Even the retaining spring of the invention is no more expensive to produce than the retaining springs known from the prior art. All that has to be ensured is that adjacent coils of the retaining spring can grasp the shoulder-shaped section in the open- edged recess of the backing plate.

It is advantageous that the retaining spring is suitable for providing a clamping engagement at the shoulder. This can be achieved by selecting a suitable thickness for the shoulder or the distance between the oppositely located surfaces of adjacent coils. For example, the aforementioned distance is somewhat smaller than the thickness of the shoulder, that is to say of the shoulder-like section, so that, compared with its normal position, the adjacent coils of the retaining spring are pushed slightly outward through the interposition of the shoulder, so that the equivalent return force of the retaining spring locks it to the shoulder.

It is advantageous that the shoulder has a depth which corresponds at least to the thickness of the retaining spring material. This ensures that the retaining spring with its coils can brace itself effectively and reliably against the shoulder without the retaining spring being able to slip from the shoulder and fall out of the recess in the backing plate.

In a further development of the invention, the recess is at least in sections configured as a segment of a circle.

Firstly, this avoids abrupt changes in geometry, which can prevent stress peaks in the backing plate. Secondly, the recess can be matched to the outside geometry of the coils of the retaining spring, so that the coils of the retaining spring butt against the recess and the retaining spring is precisely positioned geometrically with respect to the backing plate.

In accordance with a further development of the invention, the recess has a U-shaped configuration. In this way, the retaining spring can grasp the shoulder- shaped section with its coils, butt against the recess over a range of approximately 180°, and at the same time be located slightly offset to the inside with respect to the backing plate, so that the retaining spring can be even better secured against detachment from the backing plate. It is particularly advantageous if ledges are provided in the recesses, formed by the shoulder and by wall surfaces located substantially perpendicular to the shoulder. These ledges can be furnished on both sides of the shoulder, so that the radially outwardly facing surfaces of the adjacent coils of the retaining spring butt against the wall surfaces of the ledges, and the surfaces of the adjacent coils, which extend substantially parallel to the plane of the shoulder- shaped section, butt against this section. In this way, the retaining spring is reliably locked in the recess of the backing plate. Of course, the ledges can be furnished on both sides of the shoulder so that the retaining spring is locked especially reliably.

It is furthermore advantageous that the opening width of the wall surfaces of the ledges at their oppositely located open ends is slightly smaller than the outside diameter of the coils of the retaining spring. This can be achieved, for example, by furnishing raised areas on the material of the ledges and/or on the shoulder which restrict the opening width compared with the rearward area, that is, the area which faces the inside of the backing plate. On the one hand, the effect is that the retaining spring can be inserted into the recess without greater application of force ; the retaining spring must be compressed slightly in order to be able to pass the now somewhat reduced opening. On the other hand, the effect is that the retaining spring is protected against unintentional detachment from the recess in the retaining plate to the front, since an installation force must be applied which compresses the retaining spring such that it can pass through the opening, which is somewhat reduced compared with the external diameter of the coils of the retaining spring.

In the embodiment of the invention, the adjacent coils of the retaining spring are spaced apart from each other over a angular range of at least 180° and <360°. Through this selection of the angular ranges, the adjacent coils of the retaining spring on the one hand abut the shoulder-shaped section of the recess in the backing plate over a comparatively large angular range; on the other hand, the retaining spring can be dimensionally just as compact as the retaining springs known from the prior art.

It is particularly advantageous that the adjacent coils spaced apart from each other over an angular range of 180° and <360° run parallel to each other in this angular range. The effect of is that the adjacent coils in their aforementioned angular range abut the corresponding surfaces of the shoulder-shaped section of the recess in the backing plate and can thereby create an interference fit in this angular range which contributes to the retaining spring not becoming unintentionally detached from the backing plate.

In an advantageous embodiment of the invention, the adjacent coils spaced apart from each other over an angular range of 180° and <360° are connected to each other by a common section of material which extends over an angular range of >0° to 180°. The retaining spring can, for example, be made from continuous wire material, where the coils of the retaining spring grasping the shoulder- shaped section are connected over the entire section of material. In principle, the geometry of the retaining spring is conformed such that the coils are not configured in a spiral, but in steps, where the step is formed across the common section of material.

In accordance with a further advantageous embodiment of the invention, the shoulder-shaped section tapers toward the outside. This makes it easier to assemble the retaining spring in the recess in the backing plate, since the tapered open end of the shoulder-shaped section interposes itself between adjacent coils of the retaining spring, and as the retaining spring is pushed further into the recess, the coils are pushed outward by the tapered section until the adjacent coils grasp the shoulder-shaped section. The invention further relates to a backing plate for a brake pad as well as a retaining spring.

Additional advantageous embodiments and details of the invention can be found in the following description in which the invention is described and explained in greater detail with reference to the embodiment shown in the drawing.

Figure 1 shows a perspective drawing of an anchoring arrangement between a backing plate for a brake pad and a retaining spring in an unassembled state; and Figure 2 shows an anchoring arrangement between a backing plate and a retaining spring in an assembled state.

Figure 1 shows part of a backing plate 2 for a brake pad and a retaining spring in its entirety. The backing plate 2 is configured substantially plane and has an open-sided U-shaped recess 8 at its edge 6. A shoulder-shaped section projecting radially inward into the recess 8, identified in what follows as shoulder 10, is furnished in this recess. The shoulder 10 has a surface 12 facing upward in the drawing, running substantially parallel to the extensional direction of the backing plate 2. A wall surface 14 adjoins the surface 12, configured in a U- shape and extending substantially perpendicular to the extensional direction of the backing plate 2. A ledge 16 is formed by the surface 12, or by the wall surface 14.

The shoulder 10 has a corresponding bottom surface 18, as viewed in the drawing, which adjoins a wall surface 20, thereby forming a ledge 22.

The recess 8 is contained completely in a lateral area of the backing plate 2, which is slightly thinner compared with the thickness D of the backing plate in the main area 26, so that a step 28 is created.

The retaining spring 4 has substantially a coil region 30 and two open ends 32 and 34. The coil region 30 is formed substantially of an upper coil 36 and a lower coil 38, as viewed in the drawing, which are connected to each other by a common section of material 40. The two coils 36 and 38 run essentially parallel to the extensional direction of the backing plate 2, whereas the material section 40 runs at an angle thereto.

To assemble the retaining spring 4 to the backing plate 2, the retaining spring 4 shown in Figure 1 is pushed into the recess 8 in the direction indicated by the arrow 42. The retaining spring 4 is shown in its state as assembled to the backing plate 2 in Figure 2. The upper coil 36 contacts the ledge 16 shown in Figure 1, and the lower coil 38 contacts the ledge 22 shown in Figure 1. In this contact area, the coils 36 and 38 run parallel to the surfaces 12 and 18 of the shoulder 10 shown in Figure 1. The distance between the coils 36 and 38 in the area in which they are accommodated in the ledges 16 and 22 is selected such that the coils 36 and 38 grasp the shoulder 10 through a clamping action.

The retaining spring 4 is prevented from falling out of the recess 8 firstly by the space between the coils 36 and 38 being smaller than the thickness of the shoulder 10, thereby achieving a clamping effect. Secondly, on the wall surfaces 14 and 20 in the area of the edge 6, the recess 8 has inwardly projecting nibs 44, which engage the coils 36 and 38 of the retaining spring 4 from the back after it has been pushed into the recess 8.

The anchoring arrangement shown-between retaining spring 4 and backing plate 2 is so flat that it does not exceed the thickness D of the backing plate 2, thus the anchoring arrangement shown is especially compact in its dimensions and insensitive to mechanical factors, for example, to the frictional force acting on a brake pad which is attached to the backing plate.