DE102016103029A1 - Housing for a vehicle powertrain and method of making the same - Google Patents

Abstract

A housing (24) for a drive train (10) of a motor vehicle, comprising a plurality of wall portions (26) defining together a space (28) within which a drivetrain component (17) is receivable, wherein at least one of the wall portions (26a) Base thickness has. In this case, a plurality of depressions (30) is formed on the at least one wall portion (26a), within which the wall portion (26a) has a bowl thickness (46), wherein a thickness ratio of bowl thickness (46) to base thickness (44) in a range of 0.2 to 0.9.

Description

The present invention relates to a housing for a drive train of a motor vehicle, comprising a plurality of wall sections, which together define a space within which a drive train component is receivable, wherein at least one of the wall sections has a base thickness.

Furthermore, the present invention relates to a method for producing a housing of the above type, comprising the step of providing a mold for the housing, wherein the mold has at least one inlet which defines a flow direction for liquid casting material.

Drive train housing of the type described above, which are designed in particular as a gear and / or clutch housing, are usually made of metal in a casting process. The casting material may be steel alloys, light metal alloys, non-ferrous alloys and / or plastic.

The housings serve to support powertrain components such as input and output shafts, shift rails, actuators and / or clutch hubs, etc. Especially at the locations where the housings support such powertrain components, the housings must be able to accommodate high load peaks.

The housings are therefore usually first digitally modeled, in particular using the so-called finite element method. Subsequently, simulations determine where the highest loads occur. Accordingly, the housing is dimensioned, in particular from the wall thickness ago.

To increase the bending strength of certain wall sections, it is also known to provide ribbing on the inner or outer periphery. These can also provide better heat transfer, as they lead to a larger surface per wall section area.

Other considerations that play a role in the manufacture of such housings are the castability, ie whether certain shapes can be realized by casting, as well as aspects of noise generation (NVA, Noise Vibration Harshness).

Against the above background, it is an object of the invention to provide an improved powertrain housing and an improved method of manufacturing such a housing.

The above object is achieved in the aforementioned drive train housing in that a plurality of wells is formed on the at least one wall section, within which the wall section has a bowl thickness, wherein a thickness ratio of bowl thickness to the base thickness in a range of 0.2 to 0, 9 lies.

Furthermore, the above object is achieved by a method for producing a housing according to the invention, with the steps of providing a mold for the housing, wherein the mold has at least one inlet defining a flow direction for liquid casting material, wherein the formation of the wells in the Mold provided trough portions are formed so that a flow of casting material can be carried out substantially unobstructed past the trough areas.

With the provision of a housing according to the invention, in particular the following advantages can be achieved. The housing can be made with less weight. In particular, a material reduction can take place without penalizing rigidity or castability. In a differential housing for a drive train, the material savings, for example, be greater than 50 g, in particular greater than 80 g. The material reduction or weight reduction leads to a reduction of CO ₂ emissions. Furthermore, advantageously manufacturing costs can be reduced.

The housing may have good castability. In particular, the housing may be manufactured without creating greater turbulence in the casting stream.

Finally, the troughs improve the NVH properties. In some cases, due to the wells so-called NVH ribs can be omitted on a cast component. The troughs are preferably formed on an outer wall of the wall portion.

The housing is preferably a cast housing, but may also be a forged housing.

The depressions are preferably flat depressions, which in particular have a flat bottom area. The bottom area may be flat, but may also be curved, for example convex or concave. The troughs preferably do not adjoin one another.

Within the at least one wall section, a base thickness is preferably substantially constant. The at least one wall section preferably has an outer side and an inside on. The outside is preferably facing the environment, for example an engine compartment of a motor vehicle. The inside preferably faces the space defined by the wall sections.

In some embodiments, additional stiffening elements, such as ribs or beads, may be formed on the wall section.

In the case of such ribs or beads, the troughs preferably extend over such stiffening sections.

The troughs preferably form a substantially uniform pattern within the wall portion. The troughs may in particular have a uniform size. In other embodiments, they may have different sizes. However, the number of different sizes of wells within a wall section is preferably less than 4, in particular less than 3.

In the method according to the invention, a flow direction for liquid casting material within a wall section generally results due to the orientation of the wall section and the arrangement of the trough edges in relation to an inlet.

The ratio of bowl thickness to base thickness is preferably selected so that the casting material can penetrate well into the well regions in order to form the wall section in the region of the wells, but can also flow past these well regions in order to fill downstream regions of the wall section ,

The troughs are preferably shaped so that a good pourability results. In particular, transitions between a base thickness wall portion and a trough may be rounded to reduce or avoid turbulence.

In addition, the NVH behavior can be improved by the plurality of depressions within the wall section. In particular, the NVH sensitivity improves. Due to the hollows a "flat" surface of the wall portion is interrupted, so that the effect of a "speaker diaphragm" is reduced or can not arise.

During casting, due to the low mass, moreover, a faster cooling of the housing can result, which can lead to a structural improvement. This in turn can increase the casting quality.

Preferably, each of the wall sections of the housing has a plurality of wells in order to be able to realize the abovementioned advantages as far as possible for all wall sections in this way.

The calculation of the material thicknesses (bowl thickness or base thickness) is preferably carried out in the following manner. First, the housing is calculated in a conventional manner, namely in terms of load peaks, castability and possibly other parameters. This results in the individual wall sections base thicknesses, which can provide a uniform strength on the one hand and a low weight on the other hand with a uniform wall thickness within the wall section.

Starting from this model, wells of the type according to the invention are then introduced into at least one of the wall sections, so that the wall section has a smaller thickness (bowl thickness) in the region of the wells. Although this leads to an overall reduction in the material used, but without significantly reducing the strength of this wall section.

The task is thus completely solved.

It is particularly preferable that the thickness ratio is in a range of 0.65 to 0.85, more preferably in a range of 0.7 to 0.8.

With a thickness ratio in this range, the above advantages can be optimized respectively.

If the pit depth is relatively small due to this thickness ratio, the impact on the NVH is reduced. If the bowl depth is relatively large, the pourability is possibly degraded.

According to a further preferred embodiment, an area ratio of the total area of the hollows within the wall section to the total area of the wall section lies in a range of 0.5 to 0.85, in particular in a range of 0.55 to 0.8.

Particularly preferably, this area ratio is in a range of 0.65 to 0.75.

Even with this area ratio, the above-mentioned advantages can optionally be optimized.

According to a further preferred embodiment, each of the troughs has a trough surface in a range of 15 mm ² to 1500 mm ² .

Particularly preferably, the trough surface is in a range of 300 mm ² to 1000 mm ² , in particular in a range of 600 mm ² to 800 mm ² .

Even with these well surfaces, the above advantages can be optimally achieved with typical sizes of powertrain housings of the type mentioned.

According to a further preferred embodiment, the troughs are spaced from each other via a web.

The base thickness of the wall section is preferably present on the web. A mold for the housing is chosen in this case so that casting material can flow substantially in the region of the webs to fill the trough areas gradually.

According to a further preferred embodiment, in this case at least one trough edge is formed between a web and a trough having at least one radius.

As a result, the castability can be improved.

It is particularly preferred, when the trough edge is formed by a trough bottom radius, which is aligned from the trough bottom toward the trough edge, and by a subsequent trough rim radius, which merges from the trough bottom radius to the trough edge, wherein the radii are shaped differently, so that an S-contour results.

As a result, the castability can be significantly improved because turbulence can be reduced.

The radius or the radii are preferably in a range of 1 mm to 16 mm, in particular 3 mm to 9 mm, preferably 4 mm to 8 mm.

The trough bottom radius is preferably in a range of 4 mm to 8 mm. The trough rim radius is preferably in a range of 2 mm to 16 mm, in particular 4 mm to 12 mm. The trough rim radius is preferably larger than the trough bottom radius. By the radii of different sizes, the castability can be improved, wherein the surface of the trough bottom can still be comparatively large, in particular for improving the NVH properties.

According to another preferred embodiment, the troughs in the plan view have a circular shape or a polygonal shape.

In the case of a circular shape, it may be preferred if depressions of different sizes are provided in a wall section.

In a polygonal shape, it is preferable that the troughs each have a uniform polygonal shape.

The polygonal shape preferably has at least five corners, preferably not more than eight corners. It is particularly preferred if the polygonal shape is a hexagonal shape, in particular a regular hexagon shape.

In the plan view of the wall portion results in this case preferably a kind of honeycomb pattern.

In general, however, it is also possible to combine hollows of different shapes with each other.

According to another overall preferred embodiment, the housing is a casting produced by a casting process, wherein the troughs have a polygonal shape with a plurality of trough edges and wherein the troughs are positioned on the wall portion such that the number of trough edges projecting at an angle greater than 60 °, in particular of greater than 45 °, are aligned with respect to a direction of flow of material during the casting process is minimized, in particular at most one fifth, in particular at most one tenth of the total number of well edges.

In other words, it is preferable for the polygonal troughs to be positioned on the housing in such a way that casting material is deflected from trough edges at as acute an angle as possible, so that casting material can flow past the trough areas of the casting mold in order to be able to better fill following trough areas in the direction of flow ,

It is particularly preferred if the number of well edges aligned at an angle of greater than 60 ° with respect to a flow direction of material is zero.

In this embodiment, a polygonal shape of the troughs is preferable to a circular shape.

Furthermore, it is altogether advantageous if the depressions within the at least one wall section have a uniform size.

However, the troughs of a wall section may also vary in shape and size, and thus be varied with each other.

Furthermore, it is of particular advantage if at least one depression is formed in each wall section of the housing, which is larger than 1.15 times the area of a depression.

In other words, it is provided that troughs of uniform size are preferably formed over the entire area of the housing in order to realize a relatively high overall weight saving.

Overall, therefore, as many wells or depressions should be provided on the housing.

Depending on the reference surface of the wall portion, a single or may be provided a plurality of such wells. The size of the troughs with respect to the surface of the wall section must be selected so that a closed structure can be produced reliably. Stiffening measures can, as already mentioned, be implemented with ribs or beads or the like.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. Show it:

1 a schematic representation of a drive train with a perspective view of an embodiment of a housing according to the invention from the front;

2 the case of the 1 in a perspective view from behind;

3 a schematic plan view of a wall portion of a housing according to the invention;

4 a detailed perspective view of a wall portion of a housing according to the invention;

5 a schematic longitudinal sectional view through a wall portion of a housing according to the invention;

6 a detailed view of the VI 5 ; and

7 a schematic representation of a section of a mold for a housing according to the invention, namely for carrying out the method according to the invention.

In 1 is in schematic form a drive train 10 represented for a motor vehicle. The powertrain 10 includes a drive motor 12 , a clutch assembly 14 and a gear arrangement 16 , Output power from the drive motor 12 is required, via the clutch assembly 14 in the gearbox 16 directed. An output of the gearbox 16 in which a transmission component 17 included is with a differential 18 connected by means of its drive power to driven wheels 20L . 20R is distributable.

The gear arrangement 16 has an in 1 in perspective obliquely from the front illustrated housing part 24 on. The housing part 24 has a plurality of wall sections 26a . 26b . 26c . 26d on, each having a peripheral portion of the housing part 24 define and share a space 28 within which is a powertrain component, such as the transmission component 17 can be included.

The housing part 24 is preferably a transmission, a differential and / or a clutch housing and is used for example for supporting waves. That in the 1 and 2 shown housing part 24 is an intermediate housing, which includes at least one opening in a longitudinal direction and at the two axial ends unspecified flange portions for connection to other housing parts.

The wall sections 26a - 26d are each with troughs 32 are formed, which are each polygonal in plan view, in particular hexagonal, so that the wall sections 26a - 26d look honeycomb-like on the outside. The hollows 30 are from each other via bars 32 spaced.

The hollows 30 also extend over beads or ribs, as in the 1 and 2 you can see.

The hollows 30 can on an inside of the housing part 24 be formed, but are preferably formed on an outer side thereof.

3 shows in schematic form a detailed view of the housing part 24 from the outside, of a wall section 26a hereof.

It can be seen that the hollows 30 hexagonal and over bridges 32 spaced apart from each other. A trough edge is in 3 at 33 shown. The trough edge 33 is shaped so that the corners are not square, but over a Muldenumfangsradius 34 rounded, which may for example be in a range of 1 mm to 16 mm, preferably in a range of 4 mm to 10 mm.

The bridge width 36 of the bridges 32 may for example be in a range of 2 mm to 8 mm, in particular in a range of 2.5 mm to 5 mm, in particular from 3 mm to 5 mm.

The in 3 illustrated section of the wall section 26a has a total area defined by the side edges a and b. Within this total area a · b are hollows 30 present, which have a hollows total area. An area ratio of total areas of the hollows 30 inside the wall section 26a to the total area of the wall section 26a is preferably about 0.7.

Each of the troughs has a trough surface whose size is about 700 mm ² . The diameter of the trough may be for example about 30 mm.

The trough surface is in 3 schematically at 38 shown.

In 4 is shown that the hollows 30 may also extend beyond unspecified corrugations, so that they may have a curved or corrugated shape, for example.

4 further shows that the wells each have a well depth 40 may, for example, in a range of 0.3 mm to 2 mm, in particular in a range of 0.4 mm to 1.2 mm, for example, 0.8 mm.

5 shows a schematic sectional view through the wall portion 26a of the 4 wherein a substantially plane trough 30i and a corrugated trough extending across a crimp 30 ii are shown.

The wall section 26a has a base thickness 44 which may for example be in a range of 2.5 to 4.5 mm, in particular in a range of 3 mm to 3.6 mm.

Furthermore, in 5 represented by the depression 40 a bowl thickness of the wall section 26a gives (44 - 46 = 40), which can preferably take the above values.

The thickness ratio of bowl thickness 46 to base thickness 44 is preferably in a range from 0.2 to 0.9, in particular in a range from 0.4 to 0.85, in particular in a range from 0.5 to 0.85 and particularly preferably in a range from 0.65 to 0.85.

6 shows a detailed view of the VI 5 in the area of a Muldenrandes 33 ,

It can be seen that the trough 30i starting from a trough bottom first over a trough bottom radius 48 and a subsequent trough rim radius 50 in the top of the wall section 26a goes over, so to the area of the footbridge 32 out. In other words, the course of the trough edge 33 in section approximately S-shaped and in particular has no edges. In other words, the trough edge 33 steadily trained. The trough bottom radius 48 is preferably in a value range of 1 mm to 16 mm, in particular in the range of 3 mm to 9 mm, preferably from 4 mm to 8 mm. The trough rim radius 50 is preferably greater than the trough bottom radius 48 and is preferably in a value range of 2 mm to 16 mm, preferably in a range of 4 mm to 12 mm, in particular from 6 mm to 10 mm.

7 shows in schematic form a mold 60 that have a feed 62 and a schematically indicated sequence 64 includes, which may for example be designed as an overflow. Anyhow, results in the mold 60 due to the feed 62 a flow direction 66 , which is oriented so that a flow of casting material, although in trough areas 68 can flow in, where the hollows 30 be formed, however, that a large part of the casting material at the trough areas 68 flowed by, in the direction of flow 66 to be able to effectively fill the trough areas behind.

In the area between the trough areas 68 lying web areas (in 7 unspecified), the mold has a greater depth due to the existing base thickness, so that there casting material generally better and / or can flow quickly.

The trough edges are in the mold 60 positioned so that a majority of the trough edges at an angle greater than 60 ° with respect to the flow direction or flow direction 66 is aligned so that as little turbulence or the like are generated.

Claims (12)

Casing ( 24 ) for a drive train ( 10 ) of a motor vehicle, with a plurality of wall sections ( 26 ), who share a room ( 28 ) within which a powertrain component ( 17 ) is receivable, wherein at least one of the wall sections ( 26a ) a base thickness characterized in that on the at least one wall section ( 26a ) a plurality of wells ( 30 ) is formed, within which the wall section ( 26a ) a bowl thickness ( 46 ), wherein a thickness ratio of bowl thickness ( 46 ) to base thickness ( 44 ) is in a range of 0.2 to 0.9. Housing according to claim 1, characterized in that the thickness ratio is in a range of 0.65 to 0.85. Housing according to claim 1 or 2, characterized in that an area ratio of the total area of the troughs ( 30 ) within the at least one wall section ( 26a ) to the total area of the at least one wall section ( 26a ) is in a range of 0.5 to 0.85. Housing according to one of claims 1-3, characterized in that each of the troughs ( 30 ) has a trough surface in a range of 15 mm ² to 1500 mm ² . Housing according to one of claims 1-4, characterized in that the wells ( 30 ) to each other via a web ( 32 ) are spaced from each other. Housing according to claim 5, characterized in that at least one trough edge ( 33 ) between a bridge ( 32 ) and a trough ( 30 ) with at least one radius ( 48 . 50 ) is trained. Housing according to claim 6, characterized in that the radius ( 48 . 50 ) is in a range of 1 mm to 16 mm. Housing according to one of claims 1-7, characterized in that the wells ( 30 ) in plan view have a circular shape or a polygonal shape. Housing according to one of claims 1-8, characterized in that the housing ( 24 ) is a casting produced by a casting process, wherein the troughs ( 30 ) a polygonal shape with multiple well edges ( 33 ) and wherein the troughs ( 30 ) on the wall section ( 26a - 26d ) are positioned so that the number of well edges ( 33 ), which are oriented at an angle of greater than 60 ° with respect to a direction of flow of material during the casting process, is minimized. Housing according to one of claims 1-9, characterized in that the wells ( 30 ) within the wall section ( 26a - 26d ) have a uniform size. Housing according to claim 10, characterized in that in each wall section ( 26a - 26d ) of the housing ( 24 ) greater than 1.15 times the area of a trough ( 30 ), at least one trough ( 30 ) is trained. A method of manufacturing a housing according to any one of claims 1-11, comprising the steps of: - providing a mold ( 60 ) for the housing ( 24 ), the casting mold ( 60 ) an inlet ( 62 ), which has a flow direction ( 66 ) for liquid casting material, and - whereby the formation of the wells ( 30 ) in the mold ( 60 ) provided trough areas ( 68 ) are formed so that a flow of casting material substantially unhindered at the trough areas ( 68 ) can be done over.

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