Low carbon lower suspension arm
By employing steel bar sections from the 'long products' industry with a high recycled content and a forging-welding process, the suspension arm manufacturing process achieves reduced greenhouse gas emissions and cost-effective production with enhanced mechanical strength.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- RENAULT SA
- Filing Date
- 2024-02-22
- Publication Date
- 2026-04-17
AI Technical Summary
Existing manufacturing processes for motor vehicle suspension arms produce high greenhouse gas emissions due to the limited use of recycled materials in steel production, particularly in the 'flat products' industry, which emits more CO2 equivalent greenhouse gases.
The use of steel bar sections sourced from the 'long products' industry, where a higher percentage of recycled materials can be incorporated, combined with a specific forging and welding process to form a low carbon suspension arm, utilizing bainitic steel with a low carbon content for easy forging and welding, and incorporating curved sections for reinforcement.
This approach significantly reduces greenhouse gas emissions by allowing for the use of up to 80% recycled materials, while maintaining mechanical integrity and reducing manufacturing costs through the use of standard components and efficient welding.
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Abstract
Description
Title of the invention: Low carbon lower suspension arm
[0001] The present invention relates to a low carbon front lower suspension arm for a motor vehicle.
[0002] The front lower suspension arms are among the essential elements of pseudo-McPherson type suspensions, commonly implemented on motor vehicles.
[0003] They are mounted articulated on the front cradle of the vehicle, on the right and on the left, and they receive at their end a wheel support or spindle.
[0004] Each arm comprises a rear arm having a rear end and a forearm angled relative to the rear arm and terminating in a front end. Thus, the arm is connected to the cradle via the rear arm at its rear end and the elbow, while the front end of the forearm is equipped with a wheel support.
[0005] The arms are usually made from a main shell stamped from a steel plate and an additional reinforcing piece welded inside the shell. In addition, a bushing is advantageously welded at the elbow to allow it to pivot on the cradle.
[0006] Reference may be made to document EP 794 075, which describes such a lower suspension arm.
[0007] The steels used are hot-rolled steels. The hot-rolling process requires the use of materials with a recycled content of less than 30%. However, the more recycled material is used in steels, the fewer greenhouse gases are produced.
[0008] Consequently, manufacturing front suspension arms while reducing CO2 equivalent greenhouse gas emissions is limited by the rate of usable recycled material in steel.
[0009] Also, a problem which arises and which the present invention aims to solve, is precisely to provide front suspension arms for which the emission of greenhouse gas equivalent CO2 has been lowered.
[0010] In order to solve this problem, a front lower suspension arm of a motor vehicle is proposed, comprising a rear arm having a rear end adapted to be connected to a cradle of said motor vehicle and a forearm substantially bent relative to said rear arm by forming an elbow, said forearm having a front end adapted to be connected to a wheel support of said motor vehicle, while said elbow is adapted to be connected to said cradle.
[0011] And the suspension arm comprises two first sections of connected steel bar together to form said forearm and two second sections of steel bar connected together to form said forearm.
[0012] Thus, a feature of the invention lies in the use of steel bar sections. In other words, steel wire is used, sourced from the "long products" steel industry, and not from the "flat products" steel industry where steel strips are obtained by rolling. The "flat products" steel industry emits significantly more CO2 equivalent greenhouse gases overall than the "long products" industry, because it tolerates far fewer recycled materials.
[0013] Advantageously, the first and second sections of steel bar are forged in such a way as to give them a particular shape.
[0014] According to the invention, the suspension arm comprises a plurality of third sections connecting the first and second sections respectively. Thus, the first two steel bar sections and the second two steel bar sections are connected by means of third sections that are welded together. These third sections are welded between the first and second sections in predefined areas to withstand the mechanical stresses exerted on the suspension arms.
[0015] Furthermore, according to the invention, said first two sections and said second two sections are preferably substantially identical. In this way, the suspension arms are manufactured using standard components. Consequently, the manufacturing costs of these arms are reduced.
[0016] Furthermore, according to a particularly advantageous feature of the invention, said first two sections and said second two sections are curved. They are, for example, curved during forging. The advantages of such curvature will be explained in more detail later in the description.
[0017] Moreover, the third sections of said plurality of third sections are advantageously curved. However, the third sections are shorter than the first and second sections. And they are advantageously all identical, so as to minimize the number of types of parts required to manufacture the suspension arms.
[0018] According to a particularly advantageous embodiment of the invention, one of the first two steel bar sections extends along the line of one of the second two steel bar sections, while the other of the first two sections extends along the line of the other of the second two sections. Preferably, the first two sections and the second two sections are joined together by weld beads. Furthermore, the other first two sections and the other second two sections are also joined together by weld beads.
[0019] Furthermore, and as will be explained in more detail later in the description, said one of said first two sections and said one of said second two sections of steel bar define an extrados of the suspension arm, while said other of said first two sections and said other of said second two sections define an intrados.
[0020] According to a particularly advantageous embodiment of the invention, one of the first two sections and one of the second two sections are respectively coupled to two fourth sections of steel bar. The sections are advantageously coupled by means of weld beads. In this way, the suspension arm is substantially reinforced on its upper surface.
[0021] According to another embodiment, the other of the first two sections and the other of the second two sections are respectively coupled to two fifth sections of steel bar. The sections are preferably coupled by means of weld beads. In this way, the suspension arm is reinforced on its underside.
[0022] Furthermore, the rear end of the forearm comprises an annular attachment having a first axis of symmetry substantially perpendicular to the forearm, while the elbow comprises a tubular attachment having a second axis of symmetry substantially perpendicular to the first axis of symmetry. Thus, the rear end of the forearm is mounted on the cradle in a vertical tenon. The elbow is fixed to the cradle in a horizontal tenon. It will be noted that the tenons advantageously take the form of a silent block.
[0023] With regard to the steel for the sections of steel bar, a bainitic steel containing up to 0.30% carbon will be chosen, for example. Such a steel is easily forged and, moreover, given its low carbon content, is easily weldable. In this way, the sections can be forged and then more easily welded.
[0024] Moreover, the steel used in the sections comes from a long steel production line that allows for the use of 50% to over 80% recycled material. Consequently, the "carbon footprint" of such steel is much lower compared to that of flat steels.
[0025] Other features and advantages of the invention will become apparent from the following description of particular embodiments of the invention, given by way of example but not limitation, with reference to the accompanying drawings in which:
[0026] [Fig.1] is a partial schematic top view of a motor vehicle equipped with the object of the invention;
[0027] [Fig.2A] is a schematic top view of the object of the invention according to a first embodiment;
[0028] [Fig. 2B] is a schematic cross-sectional view of the object in [Fig. 2A] along plane IIB - IIB;
[0029] [Fig.3A] is a schematic top view of the object of the invention according to a second embodiment;
[0030] [Fig.3B] is a schematic cross-sectional view of the object of [Fig.3A] along plane IIIB - IIIB;
[0031] [Fig.4A] is a schematic top view of the object of the invention according to a third embodiment; and,
[0032] [Fig.4B] is a schematic cross-sectional view of the object of [Fig.4A] along the IVB - IVB plane.
[0033] Fig. 1 shows partially the front left top of a motor vehicle 10, and it is inscribed in an orthogonal coordinate system X, Y, Z, in which the X axis extends along a longitudinal front-to-rear direction of the motor vehicle, oriented towards the rear; the Y axis extends along a transverse direction of the vehicle, oriented from left to right when in a driving situation; and the Z axis extends along a vertical direction, oriented away from the ground.
[0034] Figure 1 schematically represents a chassis element 12 and a body element 14 of the motor vehicle. The chassis element 12 receives a left front lower suspension arm 16, which connects a left front wheel 18 to the chassis element 12.
[0035] The left front suspension arm 16 will be described in detail with reference to [Fig.2A] and [Fig.2B].
[0036] It comprises a forearm 20 extended by a forearm 22. The forearm 20 and the forearm 22 extend in directions substantially inclined to each other and thus define an elbow 24.
[0037] Also, the forearm 20 has a rear end 26, while the forearm 22 has a front end 28.
[0038] And according to the invention, the rear arm 20 is formed of two first sections of steel bar 30, 32, and the forearm 22 is formed of two second sections 34, 36 of steel bar.
[0039] Steel bars are produced from the "long products" steel industry and, consequently, can incorporate a high percentage of recycled steel products, commonly referred to as "scrap metal." This percentage of recycled steel products can exceed 50% and reach up to 80%. As a result, the greenhouse gas emissions from the production of these steel products are significantly lower than those from steel products directly derived from iron ore, which are used to manufacture "flat products."
[0040] With regard to the steel bar intended to make the first and second sections, a bainitic steel will be chosen, for example. In the range of steels of this type For example, a bainitic steel would be chosen. Within the range of steels of this type, one would be selected that includes, for example: up to 0.30% carbon, 0.25% silicon, 1.00% manganese, 0.50% nickel, 1.00% molybdenum, and 0.10% niobium. Such a steel is easily forged and, moreover, given its low carbon content, easily weldable. In this way, the sections can be forged and then more easily welded.
[0041] Also, the bar from which the first 30, 32 and second 34, 36 sections are made has a diameter between 15 mm and 25 mm, for example 20 mm. Furthermore, the first 30, 32 and second 34, 36 sections are all identical. They are curved, and their average radius of curvature is, for example, between 60 cm and 80 cm.
[0042] Thus, the first two 30, 32 sections are spaced apart and arranged substantially in the same plane Pm, as illustrated in [Fig. 2B]. They are also oriented so that their curvatures are in the same direction. In other words, their center of curvature is located on the same side of the forearm 20.
[0043] In addition, the first two sections 30, 32 converge substantially towards each other from the bend 24 towards the rear end 26.
[0044] The second sections 34, 36 extend respectively in the continuation of the first sections 30, 32, converging themselves, from the bend 24 towards the front end 28. They extend in the same plane as that defined by the first sections 30, 32.
[0045] Furthermore, the first 30, 32 and second 34, 36 sections are connected together by means of four third steel bar sections 40, 42, 44, 46.
[0046] The steel of the steel bar intended for the third sections is, for example, the same steel as that of the bar intended for the first 30, 32 and second 34, 36 sections. However, the diameter of the steel bar is smaller, ranging, for example, from 8 mm to 15 mm. Furthermore, the third sections 40, 42, 44, 46, all substantially identical, are shorter than the first 30, 32 and second 34, 36 sections. For example, their length is approximately equal to one-quarter of the length of the first 30, 32 and second 34, 36 sections. In addition, they are also curved. Their radius of curvature is, for example, between 20 cm and 50 cm.
[0047] Among the four third sections of steel bar 40, 42, 44, 46, a first 40 is welded to the first two sections 30, 32. It substantially joins their middle portions. Also, the concavity of the first third section 40 is oriented towards the rear end 26.
[0048] A second third section 42, oriented in the same way as the first third section 40, is connected by welding to both the first 30, 32 and second 34, 36 sections at the elbow 24. In other words, the second third section 42 is connected to the two times two ends of the first 30, 32 and second 34, 36 sections.
[0049] The third section 44 connects together one 32 of the first sections and one 36 of the second sections, which form an extrados 48 of the suspension arm 16. It is welded to both ends of these first 32 and second 36 sections and extends out of the extrados 48.
[0050] Also, the convex part of the third third section 44 extends towards the inside of the arm 16.
[0051] The fourth third section 46 extends between the two second sections 36, 34 to which it is connected by welding. It is oriented so that one of its ends is connected to one 36 of the second sections while its convex part is connected to the other 34 of the second sections and its other end is connected to the second third section 42.
[0052] The first 30, 32 and second 34, 36 sections as well as the third sections 40, 42, 44, 46 extend substantially in the same plane and they form a single rigid piece.
[0053] Furthermore, the rear end 26 of the forearm 20 is provided with an annular attachment 50 to which the first two sections 30, 32 are welded. The annular attachment 50 has a first axis of circular symmetry A, substantially perpendicular to the mean plane defined by the first 30, 32, the second 34, 36, and the third 40, 42, 44, 46 sections. This mean plane corresponds to the plane of the figure.
[0054] Furthermore, a tubular attachment 52 is connected by welding to the third section 44, outside the first 30, 32 and second 34, 36 sections, at the elbow 24. The tubular attachment 52 has a second axis of circular symmetry B, which is substantially perpendicular to the first axis of circular symmetry A. Moreover, this second axis of circular symmetry B extends substantially in the mean plane defined by the first 30, 32, the second 34, 36 and the third 40, 42, 44, 46 sections.
[0055] In addition, the front end 28 of the forearm 22 is provided with a fixing plate 54, welded to the two ends of the two second sections 34, 36. The fixing plate 54 extends substantially in the aforementioned mean plane.
[0056] Thus, the tubular bracket 52 is pivotally mounted towards the front of the chassis 12, as illustrated in [Fig. 1], and along an axis substantially parallel to the longitudinal axis of the vehicle 10. The ring bracket 50 is mounted on the chassis 12, towards the rear, so that its axis of symmetry A is oriented substantially vertically. And the mounting plate 54 is connected to the wheel support 18.
[0057] Reference will be made to [Fig. 3A] and [Fig. 3B], which illustrate, according to another embodiment, all the elements of the object of [Fig. 2A], which will present the same features. references affected by a prime sign: « ' , with in addition a doubling, of one 32' of the first sections, of one 36' of the second sections and of the third section 44'.
[0058] Thus, said first section 32', on the extrados 48', is doubled by a second first section 56. This second first section 56 extends parallel to and above said first section 32', as illustrated in [Fig.3B]. It is connected to it, for example, by welding.
[0059] Similarly, said 36' of the second sections, is doubled by a second second section 58 parallel and also extending above.
[0060] And furthermore, the third third section 44', linking together said one 32 of the first sections and said one 36 of the second sections, is itself doubled by another third third section 60 linking the second second 58 and second first sections 56.
[0061] In this way, the suspension arm 16' is reinforced, essentially on its extrados 48'.
[0062] We will now refer to [Fig.4A] and [Fig.4B] showing, according to yet another mode of implementation, an additional reinforcement opposite the extrados 48”, on the intrados side.
[0063] Also, all the elements of the object in [Fig.3A] appear in [Fig.4A] and they will have the same references marked with a double prime sign: « “. And in addition, the other 30” of the first sections, the other 34” of the second sections and all the other third sections 40”, 42” and 46” are doubled.
[0064] Thus, the said other 30” of the first sections, opposite the extrados 48', i.e. the intrados, is doubled by a third first section 62 extending parallel and above, as illustrated on the [Fig.4B].
[0065] Similarly, the said other 34” of the second sections, is doubled by a third second section 64 extending also parallel above.
[0066] And furthermore, the first third section 40'', the second third section 42'' and the fourth third section 46'' are themselves doubled by three other third sections 66, 68, 70.
[0067] In this way, the suspension arm 16”, is reinforced not only in the extrados 48”, but also on the opposite side in the intrados.
Claims
Demands
1. Front lower suspension arm (16) of a motor vehicle, comprising a rear arm (20) having a rear end (26) adapted to be connected to a cradle of said motor vehicle and a forearm (22) substantially bent relative to said rear arm (20) by forming an elbow (24), said forearm (22) having a front end (28) adapted to be connected to a wheel support of said motor vehicle, while said elbow (24) is adapted to be connected to said cradle; characterized in that it comprises two first sections of steel bar (32, 30) connected together to form said rear arm (20) and two second sections of steel bar (34, 36) connected together to form said forearm (22).
2. Front lower suspension arm according to claim 1, characterized in that it comprises a plurality of third sections (40, 42, 44, 46) respectively connecting together said first (30, 32) and second (34, 36) sections.
3. Front lower suspension arm according to claim 1 or 2, characterized in that said first two sections (30, 32) and said second two sections (34, 36) are substantially identical.
4. Front lower suspension arm according to any one of claims 1 to 3, characterized in that said first two sections (30, 32) and said second two sections (34, 36) are curved.
5. Front lower suspension arm according to any one of claims 1 to 4, characterized in that the third sections (40, 42, 44, 46) of said plurality of third sections are curved.
6. Front lower suspension arm according to any one of claims 1 to 5, characterized in that one (32) of said first two steel bar sections (30, 32) extends in line with one (36) of said second two steel bar sections (34, 36), while the other (30) of said first two sections extends in line with the other (34) of said second two sections.
7. Front lower suspension arm according to claim 6, characterized in that said one (32') of said first two sections and said one (36') of said second two sections are respectively coupled to two fourth steel bar sections (56, 58).
8. Front lower suspension arm according to claim 6 or 7, ca- characterized in that said other (30”) of said first two sections and said other (34”) of said second two sections are respectively coupled to two fifth sections of steel bar (62, 64).
9. Front lower suspension arm according to any one of claims 1 to 8, characterized in that said rear end (26) of said rear arm (20) comprises an annular attachment (50) having a first axis of symmetry A substantially perpendicular to said rear arm, while said elbow (24) comprises a tubular attachment (52) having a second axis of symmetry B substantially perpendicular to said first axis of symmetry A.
10. Front lower suspension arm according to any one of claims 1 to 9, characterized in that the steel of the steel bar sections comprises up to 0.3% carbon.
11. Front lower suspension arm according to any one of claims 1 to 10, characterized in that the steel of the sections comes from a long steel production line allowing the use of 50% to more than 80% recycled material