METHOD FOR PRODUCING A FLYWHEEL

Abstract

A method for producing a flywheel includes producing a damping plate part by permanently connecting at least a first metallic plate element provided for the flywheel to at least one further material layer to form a sandwich component. According to the method, the first plate element is connected by a joining process to at least a second, parallel plate layer, so that they lie on one another to form a disc-shaped structural unit. According to the method, at least two sheet metal layers from different materials and/or at least two sheet metal layers having different material strengths are connected with each other. This enables a large variance for the production of flywheels. In this way, it is possible, for example, to produce a flywheel having a plurality of superimposed plates adapted to the respective load situation in a defined flexibility.

Claims

1. Method for producing a flywheel, in which a damping plate part is produced by permanently connecting at least a first metallic plate element (13) provided for the flywheel to at least a second, parallel plate layer (14) by a joining process so that they lie on one another to form a disc-shaped structural unit, characterized in that at least two plate layers (13, 14) made of different materials and/or at least two plate layers (13, 14) with different material strengths are connected to each other.

2. Method according to claim 1, characterized in that the first plate layer (13) has a greater plate thickness than the second plate layer (14).

3. Method according to claim 1, characterized in that the first plate layer (13) is made of a softer steel material than the second plate layer (14).

4. Method according to claim 1, characterized in that the first plate layer (13) has a plate thickness of more than 1 mm, preferably, a plate thickness of more than 1.5 mm.

5. Method according to claim 1, characterized in that the second plate layer (14) has a plate thickness of less than 1 mm.

6. Method according to claim 1, characterized in that the first plate layer (13) consists of a thermomechanically rolled low-carbon high-strength steel material with a minimum yield strength of 355 N/mm.sup.2 that is suitable for cold forming.

7. Method according to claim 1, characterized in that the second plate layer (14) consists of a thermomechanically rolled low-carbon high-strength steel material with a minimum yield strength of 700 N/mm.sup.2 that is suitable for cold forming.

8. Method according to claim 1, characterized in that a plurality of plate layers (13, 14) each comprising plate layer pairing combinations of two plate layers (13, 14) with a different material strength and/or respectively different steel materials can be joined together.

9. Method according to claim 1, characterized in that on can connect at least two plate layers (13, 14) to each other having shaping contours that are at least in their original state before the joining process.

10. Method according to claim 1, characterized in that one can, for example, connect at least two plate layers (13, 14) to one another having cut contours that are at least different in their original state before the joining process.

11. Method according to claim 1, characterized in that one can connect at least two plate layers (13, 14) to each other having shaping contours that are at least different in their original state before the joining process.

12. Method according to claim 1, characterized in that the sandwich component comprising the first plate element (13), the second plate layer (14) and optionally further plate layers is at least partially formed from the main plane of the disc-shaped sandwich component according to the shape of the flywheel (10) and perforations or punches (18, 19) are carried out on this if applicable.

13. The method according to claim 1, characterized in that only one plate layer (13) of the disc-shaped sandwich component in a radially outer edge region obtains an upturn or a bend, which do not have the second or other plate layers (14).

14. Method according to claim 1, characterized in that the joining process of the plate layers (13, 14) also includes an additional mutual fixation of the plate layers in the radial direction by means of being clipped in.

15. The method according to claim 1, characterized in that the plate layers (13, 14) of the disc-shaped sandwich component on one another have no mutual fixation to each other and, in the radial direction and/or in the axial direction, relative position changes of the plate layers to each other in the micro-range are possible.

16. Flywheel provided for a starter of a motor vehicle, in particular for a motor vehicle with an automatic start/stop system, characterized in that it is produced according to a method according to claim 1.

Description

[0043] In the following, the present invention is explained in more detail on the basis of exemplary embodiments with reference to the enclosed drawings. The figures show:

[0044] FIG. 1 is a view of a disc-shaped output plate, which forms the basis for the production of the flywheel;

[0045] FIG. 2 a view of a double plate according to the invention for a flywheel;

[0046] FIG. 3 a schematically simplified sectional view through the double plate according to the invention along the section line A-A in FIG. 2;

[0047] FIG. 4 an enlarged detailed view of a section B from the double plate in accordance with the representation of FIG. 3.

[0048] FIG. 1 shows a disc-shaped sheet metal blank for a flywheel according to the invention before forming and further processing.

[0049] In the following, reference is made to FIG. 2. This shows in perspective a double plate for a flywheel indicated overall with the reference number 10, which was produced according to the method according to the invention. In principle, such a double plate 10 has the shape of a disc-shaped base body made of sheet metal, which is also referred to here as the carrier disc. On the outer circumference of this disc-shaped base body, for example, a ring gear (not shown here) is attached around a ring gear, for example, being welded.

[0050] The disc-shaped base body 10 has holes in different regions usually distributed across the circumference. For example, such perforations with smaller holes 18 in the region of an outer ring-shaped flat flange 11 of the carrier disc are present, each distributed at a spacing from one another across the circumference of the carrying disc 10. In addition to these smaller holes 18, for example, holes 19 may be present in other places, for example in a radial inner region 17 of the carrier disc. The hole pattern, the shape and quantity of the various holes 18, 19 is not relevant in the context of the present invention since, in principle, it rather has to do with the type of production and the structure of the flywheel according to the invention.

[0051] As can be recognized in FIG. 3, the above-mentioned central region 17 of the flywheel is formed by means of a forming method from the plate of the disc-shaped base body 10 so that this central region 17 is raised with relation to the regions adjoining radially towards the outside. This central region has a centre hole 16, wherein there is perforated ring with a plurality of the smaller holes 19, which concentrically surround the centre hole 16. However, these constructive details regarding the structure of the flywheel are not decisive for the present invention since it rather depends here more on the method of production of the disc-shaped base body 10, which, as one can recognize from FIGS. 3 and 4, a sandwich-like component is made of at least two plate layers.

[0052] This sandwich-like structure of the disc-shaped base body is explained below with reference to the sectional views in accordance with FIGS. 3 and 4. As you can easily see there, the disc-shaped base body 10 consists of a double plate, i.e. there are two plate layers parallel to each other in most regions, 13, 14, which are on one another and in principle against each other. As can be seen from FIG. 4, the first plate layer below is designed with a larger material strength of more than one mm, for example, a material strength of 1.8 mm. In comparison, the plate thickness of the second plate layer 14, which forms the upper plate layer here, is lower and lies, for example, in a range of less than 1 mm, for example, here the plate thickness of the second plate layer 14 is about 0.8 mm, which is less than half the plate thickness of the first plate layer is 13.

[0053] Furthermore, the two plate layers 13, 14 in this example consist of different steel materials, wherein the first lower plate layer 13 in the example consists of a softer steel material, for example, made of the material S355MC, while the second upper plate layer 14 consists of a harder steel material, for example, made of the material S700MC, which has a higher minimum yield strength of 700 N/mm.sup.2 compared to the first steel material, while the first softer steel material has only a minimum yield limit 355 N/mm.sup.2.

[0054] In a joining process under pressure, these two plate layers 13, 14 on one another are permanently firmly connected to each other to form a sandwich component. Experiments with regard to the noise-damping properties of such a flywheel in operation during an opening operation have shown that such a sandwich-like double plate reacts softer than a single plate when forces are applied. On the outside via the ring gear, the flywheel is connected to the gearbox during operation. In the ring gear, for example, a pinion (not shown here) engages when the flywheel is used in a start/stop device of a starter. In the central region 17, the carrier disc of the flywheel is connected to the crankshaft of the motor (these motors/gearbox elements are not shown in the present application.)

[0055] In the case of a forming of a flywheel according to the invention of 1 mm in the axial direction for example, only a force of approx. 1080 N must be applied, whereas this force is about twice as large in a conventional flywheel according to the prior art according to the prior art. As a result, important components, such as in bearings, are subjected to a significantly lower level of wear and the load of the crankshaft is considerably lower.

[0056] By doing without a viscoelastic layer, weight is saved compared to conventional solutions; the flywheel becomes lighter and has a lower mass moment of inertia. The noise-damping effect of the double plate is nevertheless very good. Instead of two plate layers on one another, three or a plurality plate layers can also be used if the corresponding application requires it.

[0057] The connection of the double plate to the two plate layers 13, 14 on the outer circumference with the ring gear of a fly wheel can be established via a weld seam for example. In their respective outer edge region, the two plate layers 13, 14 can each be shaped differently.

[0058] The two plate layers 13, 14 can also additionally be formed, for example, by means of clinching in such a way that a better mutual fixation results. This type of connection facilitates, for example, the transport of the components until assembly by welding.

[0059] According to a preferred method, the preparation of a damping plate part according to the invention, as well as a flywheel can be carried out, for example, with the following sequence of method steps:

the first plate layer 13 and the second plate layer 14 are inserted together in a press and are reshaped in this together according to the desired shape of the carrier disc to be produced in one or a plurality of steps;
if one of the plate layers in its radially outer region obtains an upturn or a bend,which is not strictly necessary,then this has the advantage that this results in a stiffening and a smoothing of the plate layer in the plane of the carrier disc;
the two plate layers are fixed to each other by means of clinching (This step is optional and not absolutely necessary.);
the two plate layers are then perforated together, according to the required hole pattern for the carrier disc plate to be produced;
the two plate layers are then preferably welded in their radially outer region both to each other as well as to a ring gear radially surrounding the plate layers on the outside;
in the radial inner region, the thus obtained carrier disc with a ring gear, which thus forms a flywheel, is connected by a screw connection to a crankshaft.

REFERENCE LIST

[0060] 10 disc-shaped base body, carrier disc
11 outer ring-shaped region
13 first (lower) plate layer
14 second (upper) plate layer
16 centre hole
17 raised centre region
18 smaller holes on the outside
19 holes all around centre hole