DE102016103029B4 - Housing for a motor vehicle drive train and method for producing the same - Google Patents

Abstract

Housing (24) for a drive train (10) of a motor vehicle, with a plurality of wall sections (26) which together define a space (28) within which a drive train component (17) can be received, at least one of the wall sections (26a). Base thickness and additional stiffening elements such as ribs or beads are formed on the wall section (26a), characterized in that a plurality of troughs (30) are formed on the at least one wall section (26a), within which the wall section (26a) has a trough thickness ( 46), wherein a thickness ratio of trough thickness (46) to base thickness (44) is in a range from 0.2 to 0.9 and the troughs extend over such stiffening sections.

Description

The present invention relates to a housing for a drive train of a motor vehicle, having a plurality of wall sections which together define a space within which a drive train component can be received, at least one of the wall sections having a base thickness.

The present invention further relates to a method for producing a housing of the above-mentioned type, with the step of providing a casting mold for the housing, the casting mold having at least one inlet which defines a flow direction for liquid casting material.

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

The housings are used to support drive train components such as input and output shafts, shift rods, actuators and/or clutch hubs, etc. The housings must be able to absorb high load peaks, particularly at the points where they support such drive train components.

The housings are therefore usually first modeled digitally, in particular using the so-called finite element method. Simulations are then used to determine where the highest loads occur. The housing is dimensioned accordingly, particularly in terms of wall thickness.

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

Further considerations that play a role in the production of such housings are castability, i.e. whether certain shapes can be achieved using casting technology, as well as aspects of noise development (NVA, Noise Vibration Harshness).

CN 204 061 822 U shows a gearbox housing with a polygonal honeycomb structure on selected surfaces, with the structure created by grooves in the material. This means that the area in the middle between the grooves has the same material thickness as the neighboring walls. In addition, although there are stiffening ribs or beads, the grooves do not extend beyond these structures.

The EN 10 2014 204 563 A1 shows a honeycomb structure with depressions between webs that differ from each other by a factor of 0.6. The structure is applied to flat wall sections. Beads or ribs are not covered with it.

EP 0 094 688 A1 shows a structure that is also created by introducing grooves.

EP 0 106 203 A1 shows ribs made of additional material so that the troughs between the ribs have a small thickness. However, the ribs are not a base thickness, but rather the filling surfaces between the ribs.

Against the above background, it is an object of the invention to provide an improved housing for a drive train and an improved method for producing such a housing.

The above object is achieved in the drive train housing mentioned at the outset in that a plurality of troughs are formed on the at least one wall section, within which the wall section has a trough thickness, with a thickness ratio of the trough 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 casting mold for the housing, the casting mold having at least one inlet which defines a flow direction for liquid casting material, which is used to form the troughs in the The trough areas provided in the casting mold are designed in such a way that a flow of casting material can take place past the trough areas essentially unhindered.

By providing a housing according to the invention, the following advantages in particular can be achieved. The case can be made with lighter weight. In particular, a reduction in material can take place without impairing the rigidity or castability. In the case of a differential housing for a drive train, the material savings can, for example, be greater than 50 g, in particular greater than 80 g. The reduction in material or weight leads to a reduction in CO2 emissions. Furthermore, manufacturing costs can advantageously be reduced.

The housing can have good castability. In particular, the housing can be manufactured without generating major turbulence in the casting stream.

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

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

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

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

Additional stiffening elements such as ribs or beads are formed on the wall section.

The troughs extend over such stiffening sections.

The troughs preferably form a substantially uniform pattern within the wall section. The troughs can in particular have a uniform size. In other embodiments, they may have different sizes. However, the number of different sizes of troughs 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 from the orientation of the wall section and the arrangement of the trough edges in relation to an inlet.

The ratio of trough thickness to base thickness is preferably selected so that the cast material can, on the one hand, penetrate well into the trough areas in order to form the wall section in the area of the troughs, but can also flow past these trough areas in order to fill areas of the wall section lying behind them in the direction of flow .

The troughs are preferably shaped in such a way that good pourability results. In particular, transitions between a wall section with a base thickness and a trough can be rounded in order to reduce or avoid turbulence.

The NVH behavior can also be improved due to the plurality of troughs within the wall section. In particular, NVH sensitivity improves. Due to the troughs, a “flat” surface of the wall section is interrupted, so that the effect of a “speaker membrane” is reduced or cannot arise.

When casting, due to the low mass, the housing can also cool down more quickly, which can lead to an improvement in the structure. This in turn can increase the casting quality.

Preferably, each of the wall sections of the housing has a plurality of troughs in order to be able to realize the above-mentioned advantages for all wall sections if possible.

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

Based on this model, troughs 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 (trough thickness) in the area of the troughs. 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 if the thickness ratio is in a range from 0.65 to 0.85, in particular in a range from 0.7 to 0.8.

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

If the trough depth is relatively small due to this thickness ratio, the impact on NVH is reduced. If the trough depth is relatively large, the castability may be deteriorated.

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

This area ratio is particularly preferably in a range from 0.65 to 0.75.

The above-mentioned advantages can also be optimized with this area ratio.

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

The trough surface is particularly preferably in a range from 300 mm ² to 1000 mm ² , in particular in a range from 600 mm ² to 800 mm ² .

With these trough surfaces, the above-mentioned advantages can also be optimally achieved with typical sizes of drive train housings of the type mentioned at the beginning.

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

The base thickness of the wall section is preferably present on the web. In this case, a casting mold for the housing is chosen so that casting material can essentially flow in the area of the webs in order to gradually fill the trough areas.

According to a further preferred embodiment, at least one trough edge is formed between a web and a trough with at least one radius.

This can improve the castability.

It is particularly preferred if the trough edge is formed by a trough bottom radius, which is aligned from the trough bottom towards the trough edge, and by an adjoining trough edge radius, which transitions from the trough bottom radius to the trough edge, the radii being shaped differently, so that an S contour results.

This can significantly improve castability because turbulence can be reduced.

The radius or radii are preferably in a range from 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 from 4 mm to 8 mm. The trough edge radius is preferably in a range from 2 mm to 16 mm, in particular 4 mm to 12 mm. The trough edge radius is preferably larger than the trough bottom radius. The castability can be improved through the radii of different sizes, although the area of the trough bottom can still be comparatively large, in particular to improve the NVH properties.

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

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

In the case of a polygonal shape, it is preferred if the troughs each have a uniform polygonal shape.

The polygonal shape preferably has at least five corners, preferably no more than eight corners. It is particularly preferred if the polygonal shape is a hexagonal shape, in particular a regular hexagonal shape.

The top view of the wall section preferably results in a kind of honeycomb pattern.

In general, however, it is also possible to combine troughs of different shapes with one another.

According to a further overall preferred embodiment, the housing is a cast part produced by means of 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 section such that the number of trough edges which are at an angle of greater than 60°, in particular greater than 45°, with respect to a flow direction of material during of the casting process is minimized, in particular at most one fifth, in particular at most one tenth of the total number of cavity edges.

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

It is particularly preferable if the number of trough edges that are 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 preferred over a circular shape.

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

However, the troughs of a wall section can also vary in shape and size, and can be combined with each other in different ways.

Furthermore, it is particularly advantageous if at least one trough is formed in each wall section of the housing that is larger than 1.15 times the area of a trough.

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

Overall, as many recesses or depressions as possible should be provided on the housing.

Depending on the reference surface of the wall section, a single or several such troughs can be provided. The size of the troughs in relation to the area of the wall section must be chosen so that a closed structure can be produced in a process-reliable manner. As already mentioned, stiffening measures can be implemented with ribs or beads or the like.

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

• 1 eine schematische Darstellung eines Antriebsstranges mit einer perspektivischen Darstellung einer Ausführungsform eines erfindungsgemäßen Gehäuses von vorne;
• 2 das Gehäuse der 1 in einer perspektivischen Ansicht von hinten;
• 3 eine schematische Draufsicht auf einen Wandabschnitt eines erfindungsgemäßen Gehäuses;
• 4 eine perspektivische Detailansicht auf einen Wandabschnitt eines erfindungsgemäßen Gehäuses;
• 5 eine schematische Längsschnittansicht durch einen Wandabschnitt eines erfindungsgemäßen Gehäuses;
• 6 eine Detailansicht VI der 5; und
• 7 eine schematische Darstellung eines Ausschnittes einer Gussform für ein erfindungsgemäßes Gehäuse, und zwar zur Durchführung des erfindungsgemäßen Verfahrens.

Exemplary embodiments of the invention are shown in the drawing 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 housing of the 1 in a perspective view from behind;
• 3 a schematic top view of a wall section of a housing according to the invention;
• 4 a perspective detailed view of a wall section of a housing according to the invention;
• 5 a schematic longitudinal sectional view through a wall section of a housing according to the invention;
• 6 a detailed view VI of the 5 ; and
• 7 a schematic representation of a section of a mold for a housing according to the invention, specifically for carrying out the method according to the invention.

In 1 A drive train 10 for a motor vehicle is shown in schematic form. The drive train 10 includes a drive motor 12, a clutch arrangement 14 and a transmission arrangement 16. Output power from the drive motor 12 is passed into the transmission arrangement 16 via the clutch arrangement 14 if necessary. An output of the transmission arrangement 16, which contains a transmission component 17, is connected to a differential 18, by means of which drive power can be distributed to driven wheels 20L, 20R.

The gear arrangement 16 has an in 1 Housing part 24 shown in perspective from the front at an angle. The housing part 24 has a plurality of wall sections 26a, 26b, 26c, 26d, which each define a peripheral section of the housing part 24 and which together define a space 28 within which a drive train component, such as the transmission component 17, can be received.

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

The wall sections 26a - 26d are each formed with troughs 32, which are polygonal in plan view, in particular hexagonal, so that the wall sections 26a - 26d look honeycomb-shaped on the outside. The troughs 30 are spaced apart from one another via webs 32.

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

The recesses 30 may be formed on an inner side of the housing part 24, 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, namely of a wall section 26a thereof.

It can be seen that the troughs 30 are hexagonal and are spaced apart from one another via webs 32. A trough edge is in 3 at 33 shown. The trough edge 33 is shaped so that the corners are not angular, but are rounded over a trough circumferential radius 34, which can be, for example, in a range of 1 mm to 16 mm, preferably in a range of 4 mm to 10 mm.

The web width 36 of the webs 32 can be, for example, in a range from 2 mm to 8 mm, in particular in a range from 2.5 mm to 5 mm, in particular from 3 mm to 5 mm.

The in 3 The section of the wall section 26a shown has a total area that is defined by the side edges a and b. Within this total area there are troughs 30 which have a total trough area. An area ratio of the total areas of the troughs 30 within the wall section 26a to the total area of the wall section 26a is preferably approximately 0.7.

Each of the troughs has a trough area whose size is approximately 700 mm<2>. The diameter of the trough can be approximately 30 mm, for example.

The trough area is in 3 shown schematically at 38.

In 4 It is shown that the troughs 30 can also extend over unspecified beads, so that they can, for example, have a curved or wavy shape.

4 further shows that the troughs can each have a trough depth 40, which can be, 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 section 26a 4 , wherein a substantially flat trough 30i and a corrugated trough 30ii extending over a bead are shown.

The wall section 26a has a base thickness 44, which can be, for example, 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 shown that the trough depth 40 results in a trough thickness of the wall section 26a (44 - 46 = 40), which can preferably take on the values mentioned above.

The thickness ratio of trough 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 preferred in a range of 0.65 to 0.85.

6 shows a detailed view VI of the 5 in the area of a trough edge 33.

It can be seen that the trough 30i, starting from a trough bottom, first passes over a trough bottom radius 48 and an adjoining trough edge radius 50 into the top of the wall section 26a, i.e. towards the area of the web 32. In other words, the course of the trough edge 33 is approximately S-shaped in section and in particular has no edges. In other words, the trough edge 33 is formed continuously. The trough bottom radius 48 is preferably in a value range from 1 mm to 16 mm, in particular in the range from 3 mm to 9 mm, preferably from 4 mm to 8 mm. The trough edge radius 50 is preferably larger than the trough bottom radius 48 and is preferably in a value range from 2 mm to 16 mm, preferably in a range from 4 mm to 12 mm, in particular from 6 mm to 10 mm.

7 shows in schematic form a mold 60, which contains an inlet 62 and a schematically indicated drain 64, which can also be designed as an overflow, for example. In any case, a flow direction 66 results in the mold 60 due to the inlet 62, which is aligned in such a way that a flow of casting material can flow into trough areas 68 in which the troughs 30 are formed, but that a large part of the casting material flows past the trough areas 68 in order to be able to effectively fill trough areas behind them in the flow direction 66.

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

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

Claims (12)

Housing (24) for a drive train (10) of a motor vehicle, with a plurality of wall sections (26) which together define a space (28) within which a drive train component (17) can be received, at least one of the wall sections (26a). Base thickness and additional stiffening elements such as ribs or beads are formed on the wall section (26a), characterized in that a plurality of troughs (30) are formed on the at least one wall section (26a), within which the wall section (26a) has a trough thickness ( 46), wherein a thickness ratio of trough thickness (46) to base thickness (44) is in a range from 0.2 to 0.9 and the troughs extend over such stiffening sections. Housing according to Claim 1 , characterized in that the thickness ratio is in a range of 0.65 to 0.85. Housing after 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 from 0.5 to 0.85. Housing according to one of the Claims 1 - 3 , characterized in that each of the troughs (30) has a trough area in a range of 15 mm<2> to 1500 mm<2>. Housing according to one of the Claims 1 - 4 , characterized in that the troughs (30) are spaced from each other via a web (32). Housing after Claim 5 , characterized in that at least one trough edge (33) is formed between a web (32) and a trough (30) with at least one radius (48, 50). Housing after Claim 6 , characterized in that the radius (48, 50) is in a range of 1 mm to 16 mm. Housing according to one of the Claims 1 - 7 , characterized in that the troughs (30) have a circular shape or a polygonal shape in plan view. Housing according to one of the Claims 1 - 8th , characterized in that the housing (24) is a cast part produced by means of a casting process, the troughs (30) having a polygonal shape with a plurality of trough edges (33) and the troughs (30) being positioned on the wall section (26a - 26d). are that the number of trough edges (33), which are aligned at an angle of greater than 60 ° with respect to a flow direction of material during the casting process, is minimized. Housing according to one of the Claims 1 - 9 , characterized in that the troughs (30) within the wall section (26a - 26d) have a uniform size. Housing after Claim 10 , characterized in that at least one trough (30) is formed in each wall section (26a - 26d) of the housing (24), which is larger than 1.15 times the area of a trough (30). Method for producing a housing according to one of Claims 1 - 11 , with the steps: - providing a mold (60) for the housing (24), the mold (60) having an inlet (62) which defines a flow direction (66) for liquid casting material, and - wherein the for forming the Trough regions (68) provided in the mold (60) are designed in such a way that a flow of casting material can take place past the trough regions (68) essentially unhindered.

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