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Title:
A CROSS MEMBER OF AN AXLE ASSEMBLY FOR A LIGHT COMMERCIAL VEHICLE
Document Type and Number:
WIPO Patent Application WO/2017/158535
Kind Code:
A1
Abstract:
A cross member of an axle assembly for a light commercial vehicle, the cross member (1) comprising: a single body (2) extending along an axis (Al) transverse to a direction of travel (V) of the axle assembly (1); the single body (2) being produced in an aluminium-silicon alloy as one piece by means of a casting process, preferably at high pressure; the single body (2) comprising a first structure (11, 24) having a closed section, preferably the first structure (11, 24) being hollow.

Inventors:
FERRARIO DAVIDE (IT)
CECCHEL SILVIA (IT)
GOLIMBIOSCHI ROBERT EDUARD (IT)
Application Number:
PCT/IB2017/051510
Publication Date:
September 21, 2017
Filing Date:
March 15, 2017
Export Citation:
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Assignee:
STREPARAVA S P A CON SOCIO UNICO (IT)
International Classes:
B62D21/11; B62D29/00
Foreign References:
DE102012213663A12014-02-06
EP0779204A11997-06-18
US20160068189A12016-03-10
EP1270374A22003-01-02
Attorney, Agent or Firm:
BOGGIO, Luigi et al. (IT)
Download PDF:
Claims:
CLAIMS

1. A cross member of an axle assembly for a light commercial vehicle, the cross member (1) comprising: a single body (2) extending along an axis (Al) transverse to a direction of travel (V) of the axle assembly (1) ; the single body (2) being produced in an aluminium-silicon alloy as one piece by means of a casting process, preferably at high pressure; the single body (2) comprising a first structure (11, 24) having a closed section, preferably the first structure (11, 24) being hollow.

2. The cross member of claim 1, the single body (2) comprising a second structure (12; 25) having a closed section, preferably aligned with the first structure (11, 24) transverse to the first axis (Al), in particular perpendicularly.

3. The cross member of claim 2, wherein the first and the second structure (11, 12; 24, 25) are connected to each other by means of a first ribbing (16; 26) of the single body (2), preferably the first ribbing (16; 26) extending transverse to the first axis, in particular perpendicularly .

4. The cross member of any one of the preceding claims, the single body (2) comprising a first rib (10) connected to the first section (11) by means of a second ribbing (15), preferably transverse to the first axis (Al ) , in particular perpendicular.

5. The cross member of claim 4, having a first portion (20) of the single body (2) having a portion of the first structure (11) and a portion of the first rib (10) and being connected to each other by means of the second ribbing ( 15) .

6. The cross member of any one of the preceding claims, having a second portion (21, 22) of the single body (2) having a portion of the first structure (11) and a portion of the second structure (12) and connected to each other by means of a connecting section (18) or a first ribbing (16) .

7. The cross member of any one of the preceding claims, the single body (2) comprising a third structure (24) with a closed section having a dimension (Dl) transverse to the axis (Al ) greater than a dimension (D2) transverse to the axis (Al) of the first structure (11) .

8. The cross member of claim 7, comprising a fourth structure (24) with a closed section, which in use is arranged above the third structure (23) with closed section .

9. The cross member of one of claims 5 to 8, wherein the single body (2) comprises a central sector (3) and two lateral sectors (4) that extend from the central section (3) from opposite sides.

10. The cross member of any one of the preceding claims, the single body (2) comprising a second rib (17) which in use is facing the ground and is preferably parallel to the axis (A) ; and a plurality of second ribbings (15) that extend transverse to the axis (Al) from the second rib (17) and wherein at least one of the plurality of second ribbings (15) forms an angle with the second rib between 60° and 120°, preferably between 75° and 105° .

11. An axle assembly comprising

- two suspensions;

- a cross member according to any one of the preceding claims; and

- two hub assemblies articulated to the subframe by means of the respective suspensions;

wherein each suspension comprises:

- a mechanical joint for articulated connection of the hub assembly to the cross member.

12. Production process of a cross member of an axle assembly, the production process comprising a step of casting, preferably at high pressure, with an aluminium- silicon alloy; and a step of producing at least one carriage (31) for producing at least one structure (11; 12; 24; 25) with a hollow section of the cross member (1) .

13. Production process of claim 12, comprising the step of producing a casting die that defines the ribbings (15) of the cross member (1) that extend from a second rib (17) of the cross member (1), preferably the second rib (17) being on a lower side of the cross member (1); arranging the casting gates (30) in proximity of the second rib (17); and comprising the step of arranging the casting gates (30) and/or defining the ribbings (15) so that an angle formed between the one of the casting gates (30) and one of the ribbings (15) is between 150° and 210°, preferably between 165°and 195° .

14. Production process of claims 12 or 13, wherein the casting process is performed at high pressure and under vacuum.

15. Production process of one of claims 12 to 14, comprising the step of producing the cross member in a single body ( 2 ) .

Description:
"A CROSS MEMBER OF AN AXLE ASSEMBLY FOR A LIGHT COMMERCIAL VEHICLE"

TECHNICAL FIELD

The invention relates to a cross member for an axle assembly for a light commercial vehicle, to said axle assembly and to a process for the production of the cross member.

BACKGROUND ART

The use of light commercial vehicles is becoming more and more common, especially in urban and suburban contexts for the transportation of objects. Commercial vehicles require high performances in terms of flexibility and ease of handling. In particular, they should be very sturdy both in supporting heavy loads and in resisting impacts, strains and stresses, due for example to uneven grounds.

The axle assembly of a light commercial vehicle currently comprises a cross member, two suspensions and hub assemblies articulated to the cross member by means of the respective suspensions.

The cross member of the axle assembly of the light commercial vehicle is manufactured by welding a plurality of pieces of pressed and/or bent sheet metal. Finally, the cross member is subjected to cataphoresis and painting operations as well as to other possible machining processes .

A drawback of the prior art lies in the fact that these cross members are very heavy, with a weight that increases as the need to resist impacts, strains and stresses becomes stronger. This leads to a significant fuel consumption of the respective commercial vehicle.

DISCLOSURE OF INVENTION

An object of the invention is to provide a cross member that reduces the drawback of the prior art.

According to the invention, there is provided a cross member of an axle assembly for a light commercial vehicle; the cross member comprising a single body extending along an axis transverse to a direction of travel of the axle assembly; the single body being produced in an aluminium- silicon alloy as one piece by means of a casting process, preferably at high pressure; the single body comprising a first structure having a closed section, preferably the first closed section is hollow. Thanks to the invention, the cross member made of aluminium has a high resistance to impacts, strains and stresses, though with a low weight.

According to a preferred embodiment of the invention, the single body comprises a second structure having a closed section, preferably aligned with the first structure transverse to the first axis, in particular perpendicularly .

According to another preferred embodiment of the invention, the first and the second structure are connected to each other by means of a first ribbing obtained in the single body, preferably the first ribbing extends transverse to the first axis, in particular perpendicularly .

According to another preferred embodiment of the invention, the single body comprises a first rib connected to the first section by means of a second ribbing, preferably transverse to the first axis, in particular perpendicular .

According to another preferred embodiment of the invention, the cross member comprises a first portion of the single body having a portion of the first structure and a portion of the first rib and being connected to each other by means of the first ribbing.

According to another preferred embodiment of the invention, the cross member comprises a second portion of the single body having a portion of the first structure and a portion of the second structure with a closed section and connected to each other by means of a connecting section or the second ribbing.

According to another preferred embodiment of the invention, the single body comprises a third structure with a closed section having a dimension transverse to the axis greater than a dimension transverse to the axis of the first structure, the dimensions being preferably perpendicular to the axis.

According to another preferred embodiment of the invention, the single body comprises a fourth structure with a closed section, which in use is arranged above the third structure with a closed section.

According to another preferred embodiment of the invention, the single body comprises a central sector and two lateral sectors that extend from the central sector on opposite sides. The central sector comprises the first portion and the second portion.

According to another preferred embodiment of the invention, the single body comprises a second rib which in use is facing the ground and is preferably parallel to the axis; and a plurality of ribbings that extend transverse to the axis from the second rib and wherein at least one of the plurality of ribbings forms an angle with the second rib between 60° and 120°, preferably between 75° and 105°. In particular, the plurality of ribbings form respective angles with second rib between 60° and 120°, preferably between 75° and 105°.

Another object of the invention is to provide an axle assembly that can reduce the drawbacks of the prior art.

According to the invention, there is provided an axle assembly comprising:

- two suspensions;

- a cross member according to any one of the claims from 1 to 10; and

- two hub assemblies articulated to the subframe by means of the respective suspensions;

wherein each suspension comprises:

a mechanical joint for articulated connection of the hub assembly to the cross member.

Another object of the invention is to provide a production process of a cross member of an axle assembly.

According to the invention, there is provided a production process of a cross member of an axle assembly; wherein the production process comprises a step of casting, preferably at high pressure, with an aluminium-silicon alloy and a step of producing carriages for producing at least one structure with a hollow section of the cross member .

According to a preferred embodiment of the invention, the process comprises the step of producing a casting die that defines the ribbings of the cross member that extend from a second rib of the cross member; arranging the casting gates in proximity of the second rib; and wherein the two processes comprise the step of arranging the casting gates and/or defining the ribbings so that an angle formed between one of the casting gates and one of the ribbings is between 150° and 210°, preferably between 165°and 195° .

According to another preferred embodiment of the invention, the casting process is performed at high pressure and under vacuum.

According to another preferred embodiment of the invention, the production process comprises the step of producing the cross member in a single body.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will be best understood upon perusal of the following description of a non-limiting embodiment thereof, with reference to the accompanying drawing, wherein:

- figure 1 is a front view of a cross member for an axle assembly according to the invention;

- figure 2 is a front view with sectional parts and with a lateral carriage used for a step of the cross member production process;

- figure 3 is a cross section view according to plane III-III of figure 1 ;

- figure 4 is a cross section view according plane IV-

IV of figure 1; and

- figure 5 is a cross section view according plane V-V of figure 1.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to figure 1, number 1 indicates a cross member of an axle assembly for a light commercial vehicle.

The axle assembly (not shown in the accompanying figures) comprises the cross member 1 extending along an axis Al transverse to a direction of travel V of the light commercial vehicle; two suspensions (not shown) ; two hub assemblies (not shown) articulated to the cross member 1 by means of the respective suspensions; and a steering system (not shown) arranged along the cross member 1 and connected to the two hub assembly so as to steer the hub assemblies.

The cross member 1 comprises a single body 2, which extends along the axis Al and is manufactured as one single piece by means of a casting process, preferably die casting. In other words, the cross member 1 is formed by one single piece. The single body 2 is made of an aluminium-silicon alloy. Furthermore, the cross member 1 is symmetrical relative to a symmetry plane P, which is perpendicular to the axis Al .

The single body 2 has a central sector 3 and two lateral sectors 4, which extend towards opposite sides of the central sector 3 and partly transversely to the axis Al . In other words, the two lateral sectors 4 are arranged at the ends of the central body 3 on opposite sides.

With reference to figure 1, the cross memberl has through holes 5, in particular two upper through holes 5 and two lower through holes 5, which are configured for the attachment of the suspensions. The upper through holes 5 are obtained on the lateral sectors 4 transversely to the axis Al, in particular perpendicularly to the axis Al and parallely to the direction of travel. The lower through holes 5 are obtained between the central sector 3 and the respective lateral sectors 4. In other words, the suspensions are connected to the cross member 1, in particular to the lateral sectors 4 of the cross member 1 by means of the through holes 5.

Furthermore, the cross member 1 comprises through holes 6 having a smaller diameter than the through holes 5 and configured for the attachment of the steering system. The through holes 6 are obtained in the central sector 3 transversely to the axis Al, in particular perpendicularly to the axis Al and parallely to the direction of travel. In other words, the hydraulic steering system is connected to the cross member 1, in particular to the central sector 3 of the cross member 1 by means of the through holes 6.

With reference to figures 1 and 2, the central sector 3 is symmetrical relative to the symmetry plane P and comprises an upper rib 10, which extends along the central sector 3 connecting the lateral sectors 4 to each other, and two structures 11, which have a closed section and are symmetrical to each other relative to the plane P. Each structure 11 extends from the plane P towards the respective lateral sector 4. Furthermore, the two structures 11 are connected to each other along the plane P.

Furthermore, the central sector 3 comprises two structures 12, which have a closed section and are symmetrical to each other relative to the plane P. The two structures 12 are spaced apart from one another and are adjacent to the respective lateral sector 4.

In use, the structures 11 are located under the structures 12. In other words, in use, the structures 11 are closer to the ground than the structures 12.

The central sector 3 has a lower rib 17, which is arranged along a lower side of the structures 11. In other words, one of the sides of the structures 11 that faces the outside of the cross member 1 defines the lower rib 17. The lower rib 17, in use, is adjacent to the ground and is arranged on the opposite side of the cross member 1 relative to the upper rib 10. The lower rib 17 extends between the lower holes 5 and fulfils the structural function of distributing the loads on the lower holes 5 along the entire central sector 3.

Furthermore, the central sector 3 comprises a plurality of ribbings 15, which connect the structure 11 to the upper rib 10. More in detail, a group of the plurality of ribbings 15 extend from the lower rib 17 to the upper rib 10. In particular, said ribbings of said group of the plurality of ribbings 15 extend, along a first portion, on the side of the lower structures 11 and, along a second portion, from respective upper walls 11a of the lower structures 11 to the upper rib 10. Furthermore, another group of the plurality of ribbings 15a extend from the upper wall 11a of the lower structure 11 to the upper rib 10.

Furthermore, the central sector 3 comprises two ribbings 16, which connect the structure 11 to the structure 12.

With reference to figure 5, you can see a section of a portion 20 of the central sector 3 of the single body 2, where there are the lower structure 11 having the closed section, the upper rib 10 and one of the ribbings 15 of the plurality of ribbings 15 connecting the structure 11 to the upper rib 10. The ribbing 15 is transverse to the axis Al, in particular perpendicular.

With reference to figure 3, the single body 2 comprises a connecting section 18, which connects the structure 11 to the structure 12. More in detail, figure 3 shows a section of a portion 21 of the central sector 3, where there are the structure 11 having the closed section, the structure 11 having the closed section and the connecting section, which connects the closed section of the structure 11 to the closed section of the structure 12. The connecting section 18 is open and its cross section is substantially C-shaped. Furthermore, in use, the connecting section 18 houses the fixing means to fix the steering system to the cross member 1. In the portion 21, one of the upper sides of the closed section of the structure 12 defines a portion of the upper rib 10. In other words, an outer side of the closed section of the structure 12 defines a portion of the upper rib 10. The outer side of the closed section of the structure 12 is the farthest side of the structure 12 from the lower rib 17. The connecting section 18 comprises a portion that is transverse to the axis Al, in particular perpendicular.

With reference to figure 4, you can see a section of a portion 22 of the central sector 3, where there are the structure 11 having the closed section, the structure 11 having the closed section and the ribbing 16, which connects the closed section of the structure 11 to the closed section of the structure 12. In the portion 22, one of the upper sides of the structure 12 defines a portion of the upper rib 10. In particular, the upper side is farthest from the lower rib 17 of the sides of the structures 12. The ribbing 16 is transverse to the axis Al, in particular perpendicular .

With reference to figures 1 and 2, each lateral sector 4 comprises a structure 24 with a closed section having a dimension Dl transverse to the axis Al that is greater than a dimension D2 transverse to the axis Al of the structure 11 and than a dimension D3 transverse to the axis Al of the structure 12. In particular, the dimension Dl of the structure 24 is greater than the sum of the dimension D2 of the structure 11 and the dimension D3 of the structure 12. The dimensions are preferably perpendicular to the axis Al .

Furthermore, each lateral sector 4 comprises a structure 25 having a closed section. The structure 24 and the structures 25 are connected by means of a bracket 26, which is solid and has a thickness that is approximately equal to twice the thickness of the ribbing 16. The thickness of the bracket 26 is approximately equal to twice the thickness of the ribbing 15. The thickness of the bracket 26 is approximately equal to twice the thickness of the walls of the structure 11. Furthermore, the structure 25 is arranged, in use, above the structure 24. In other words, the structure 25 is farther from the lower rib 17 than the structure 24. In other words, in use, the structure 25 is farther from the ground than the structure 24.

The bracket 26 houses, in use, a bounce buffer 26a, which limits the stroke of suspension connected to the hole 5 downwards. The cross member 1 comprises a seat 26b, which houses an upper buffer, which limits the stroke of the suspension connected to the hole 5 upwards. The cross member 1 comprises ribbings 27 around the seat 26b.

The upper holes 5 are made in the structure 25 and the lower holes 5 are made in the structure 24. The suspensions are partly housed inside the respective structures 24 and 25.

With reference to figures 1 and 2, as already mentioned above, the plurality of ribbings 15, which extend from the lower rib 17 towards the upper rib 10 on the side of the structure 11, form an angle with the lower rib 17 that ranges from 60° to 120°, preferably from 75° to 105°.

As already mentioned above, the structures 11, 12, 24 and 25 are hollow.

With reference to the accompanying figures, the thicknesses of the walls of the structures 11, of the structures 12, of the ribbings 15, of the ribbings 16 and of the connecting section 18 approximately have the same dimensions; in other words, the thicknesses have dimensions that differ from each other by less than 30%, preferably less than 15%. By so doing, you can avoid the formation of air bubbles during the production process of the single body 2 and, as a consequence, the resistance to impacts of the cross member 1 is greater.

Furthermore, with reference to the accompanying figures and for greater clarity, the following information should be pointed out.

The structure 11 is part of the single body 2.

The structure 12 is part of the single body 2.

The structure 24 is part of the single body 2.

The structure 25 is part of the single body 2.

The plurality of ribbings 15 are part of the single body 2.

The ribbings 16 are part of the single body 2.

The connecting section 18 is part of the single body

2.

The bracket 26 is part of the single body 2.

The ribs 10 and 17 are part of the single body 2.

The ribbings 27 are part of the single body 2.

In other words, the cross member 1, with the exception of the bounce buffer, is entirely made in the single body 2, which is one single piece of the primary aluminium- silicon alloy.

With reference to figure 1, the broken lines show the casting gates 30, which are used during the production process of the cross member 1. On the other hand, figure 2 shows the carriages 31, which are used during the production process to manufacture the structures 11, 12, 24 and 25.

More in detail and with reference to figure 1 and 2, the production process of the cross member 1 comprises the steps of:

a) manufacturing a die having the profiles of the ribbings 15, 16, 26 and of the connecting section 18;

b) manufacturing the carriages 31 having the profiles of the hollow structures 11, 12, 24 and 25 with a closed section;

c) preparing the casting gates 30 aligned with the ribbings 15, in particular so that between the angle between the casting gates 30 and the ribbings 15 ranges from 150° to 210°, preferably from 175° to 195°; and

d) using a casting process, preferably at high pressure, using a primary aluminium-silicon alloy. The production process further comprises the step of manufacturing the cross member in a single body 2.

In a preferred version of the invention, the casting process is performed at high pressure, namely it is a die casting process carried out at a pressure greater than 100 bar and under vacuum.

In another embodiment, the casting process is performed at low pressure, namely at a pressure ranging from 0.2 bar to 1 bar and under vacuum. The casting process is carried out at a controlled pressure.

In another embodiment, the casting process is performed at high pressure, namely by means of die casting, or at low pressure without the aid of the vacuum.

Finally, it is clear that the axle assembly can be subjected to changes and variations, without for this reason going beyond the scope of protection of the appended claims .