KR20240003217A - Method of manufacturing a torsion beam for a vehicle suspension and vehicle suspension - Google Patents

Abstract

The present invention relates to a torsion beam manufacturing method for a vehicle suspension system and a vehicle suspension system that can simultaneously achieve weight reduction while reinforcing the strength of the weak portion of the torsion beam, wherein a first plate having a first thickness corresponds to the lower part of the torsion beam. A lower plate molding step of forming a lower plate of a shape that is similar to It may include an assembling step of assembling the upper plate to the upper side and a welding step of welding a connection portion of the lower plate and the upper plate to form the torsion beam.

Description

Method of manufacturing a torsion beam for a vehicle suspension and vehicle suspension {Method of manufacturing a torsion beam for a vehicle suspension and vehicle suspension}

The present invention relates to a torsion beam manufacturing method for a vehicle suspension system and a vehicle suspension system. More specifically, the present invention relates to a torsion beam manufacturing method for a vehicle suspension system and a vehicle suspension system that can simultaneously achieve weight reduction while reinforcing the strength of vulnerable parts of the torsion beam. It's about.

The suspension system of a passenger car is an essential part of vehicle operation that connects the body, powertrain, driving parts, and wheels. These suspension systems are divided into front and rear wheels. The rear suspension system uses a torsion beam axle (CTBA, Coupled Torsion Beam Axle), which has fewer parts and a simpler structure than the multi-link type, which is advantageous for manufacturing costs, mainly for small and medium-sized vehicles. It is widely adopted.

Generally, the torsion beam axle consists of a trailing arm that can be connected to the wheels and car body, and a torsion beam that connects the center portion of the left and right trailing arms and crosses. The torsion beam is an important component that controls the attitude of the wheels through torsion action of the wheel movement that occurs while the vehicle is running. Depending on the manufacturing method and cross-sectional shape of the torsion beam, it can be largely divided into a combination of a V beam and a torsion bar and a tubular. It can be classified into two beam types. The combination of V beam and torsion bar has excellent torsional resistance, but due to the increase in the weight of parts, there is a recent trend of specifications for reasons such as vehicle weight reduction, and tubulars can maximize vehicle weight reduction. The beam type is mainly used.

Automotive suspension systems are safety components related to vehicle driving, and require verification of high durability performance. In the case of the conventional tubular beam type torsion beam, repeated durability tests are conducted by simulating the torsional behavior that occurs during vehicle operation. In the case of the tubular beam type torsion beam, during the development process, cracks occurred on the side of the beam where the torsion moment occurs based on the center of the torsion beam, and there was a problem that the material strength and thickness had to be reinforced to ensure a high durability life.

In the conventional tubular beam type torsion beam, in order to realize a closed cross-section, a pipe was manufactured and then molded with a press mold to form a tubular beam with a closed cross-section in the shape of a “V”. However, when forming a tubular beam with a “V”-shaped closed cross-section using a rough pipe material like this, there was a problem in that cracks easily occurred in the earing portion of the beam where stress concentration occurred during forming.

The earring part is a part where plastic deformation occurs during molding and molding cracks easily occur, and stress concentration can occur as a torsional load is applied after molding the product. Therefore, in order to relieve stress concentration in the earring portion, a structure is needed that can avoid rapid shape changes during molding and relieve stress even when a load is applied.

Recently, some automobile manufacturers have formed variable cross-section tubular beams by forming pipes using a hydroforming method, and have also formed “V”-shaped tubular beams by applying deformed blanks, forming them with a press, and then welding them. However, since the hydroforming method requires good formability because it is formed using a mold after expanding the pipe material, there was a problem in applying it to high-strength materials. To solve this problem, the shape was changed using a deformed blank. A method of forming a tubular beam by forming has been recently applied, but this method also has many problems in that it is still difficult to apply to high-strength materials due to problems such as springback after forming.

The present invention is intended to solve various problems including the above-mentioned problems. The purpose of the present invention is to provide a torsion beam manufacturing method for a vehicle suspension system and a vehicle suspension system that can simultaneously achieve weight reduction while reinforcing the strength of the vulnerable portion of the torsion beam. do. However, these tasks are illustrative and do not limit the scope of the present invention.

According to one embodiment of the present invention, a method for manufacturing a torsion beam of a vehicle suspension system is provided. The method of manufacturing a torsion beam of a vehicle suspension system includes: a first plate having a first thickness for manufacturing a torsion beam having a “V”-shaped closed cross-section in at least some sections; A lower plate forming step of forming a lower plate with a shape corresponding to the lower portion of the torsion beam; A top plate forming step of forming a second plate having a second thickness different from the first thickness into a top plate of a shape corresponding to the upper portion of the torsion beam; An assembly step of assembling the upper plate on the upper side of the lower plate; and a welding step of welding a connection portion of the lower plate and the upper plate to form the torsion beam.

According to one embodiment of the present invention, the first thickness of the first plate may be formed to be thicker than the second thickness of the second plate.

According to one embodiment of the present invention, the difference in thickness between the first thickness and the second thickness may be at least 0.5 mm or more.

According to one embodiment of the present invention, the torsion beam is formed with an outer bent portion of the curved portion as the upper plate portion having the second thickness, based on a “V”-shaped closed cross-section, and an inner bent portion of the curved portion. and earring portions at both ends may be formed of the lower plate portion having the first thickness.

According to one embodiment of the present invention, in the lower plate forming step, the first plate is formed into a “W”-shaped cross section so that the lower plate can form the inner bent portion and the earring portion of the curved portion of the torsion beam. It can be formed by bending.

According to one embodiment of the present invention, in the lower plate forming step, the lower plate that is bent and molded to have a “W”-shaped cross section is sequentially bent and formed at least twice at least twice by press molding at least twice. It can be.

According to one embodiment of the present invention, in the upper plate forming step, the second plate is bent and formed to have a “V” shaped cross section so that the upper plate can form the outer bent portion of the curved portion of the torsion beam. can do.

According to one embodiment of the present invention, in the upper plate forming step, the upper plate that is bent and molded to have a “V”-shaped cross section is sequentially bent and formed at least twice at least twice by press molding. It can be.

According to one embodiment of the present invention, the assembling step is performed by forming a “W” shape of the lower plate so that both sides of the first plate that is bent and formed to have a “W” shaped cross section can be held in the lower plate forming step. A first flange portion cutting step of cutting a pair of first flange portions formed on both sides of the cross section; In the upper plate forming step, a pair of second flanges formed on both sides of the “V” shaped cross section of the upper plate are provided to hold both sides of the second plate that is bent and formed to have a “V” shaped cross section. A second flange portion cutting step; And a seating step of flipping the upper plate, which has been bent and molded to have a “V” shaped cross section, into a “∧” shape and seating it on the upper side of the lower plate, which has been bent and molded to have a “W” shaped cross section. there is.

According to one embodiment of the present invention, in the assembling step, after the seating step, the pair of first flange portions of the lower plate covers at least a portion of the inclined surface of the upper plate, so that the ends of the pair of first flange portions It may further include a bending step of further bending the pair of first flange portions inward so that the inclined surface of the upper plate comes into contact with the upper plate.

According to one embodiment of the present invention, in the second flange portion cutting step, the pair of second flange portions are cut in a shorter length than the pair of first flange portions cut in the first flange portion cutting step. It can be cut.

According to one embodiment of the present invention, in the welding step, the ends of the pair of first flange parts and the contact portion of the inclined surface of the upper plate may be welded.

According to another embodiment of the present invention, a suspension device for a vehicle is provided. The vehicle suspension device may include a torsion beam of the vehicle suspension device manufactured by the method of manufacturing the torsion beam of the vehicle suspension device.

According to an embodiment of the present invention made as described above, the upper and lower sections of the closed cross-section were separated so that the thickness and shape could be changed, and the upper and lower plates were separated and shaped in places where durability was not affected. , By joining through welding, plastic deformation occurs at the durable weak portion of the lower part of the torsion beam where a large torsional moment can occur and during molding, which can easily cause molding cracks and stress concentration can occur due to the torsional load imposed even after molding the product. It is possible to manufacture a torsion beam where the upper part has a thick thickness and the upper part, which has little effect on the twisting moment, has a relatively thin thickness.

In this way, it is possible to produce a tubular beam type torsion beam through press molding without manufacturing, and by producing the upper and lower plates separately through press molding, the thickness can be different from each other, and the steel type can also be designed differently. , Since the upper and lower plates are molded differently, it can have an advantageous effect in terms of formability compared to the conventional method of manufacturing a torsion beam by molding using a single blank.

In addition, since there is an advantage in that the width of the panel can be made different when molding using the press method, molding is possible even when manufacturing variable cross-section CTBA tubular beams, and the durability of the part is improved and lightweight by reinforcing the thickness of the weak durability part of the torsion beam. It is possible to implement a torsion beam manufacturing method and a vehicle suspension device that can simultaneously achieve. Of course, the scope of the present invention is not limited by this effect.

1 is a process flow chart sequentially showing a method of manufacturing a torsion beam of a vehicle suspension system according to an embodiment of the present invention.
Figures 2 to 5 are perspective views schematically showing each manufacturing process of a torsion beam of a vehicle suspension system according to the process flow chart of Figure 1.
Figure 6 is an image comparing the results of analyzing the torsional load stress distribution of the torsion beam of the conventional vehicle suspension system and the torsion beam of the vehicle suspension system of the present invention.
Figure 7 is an image showing an actual product of a vehicle suspension system manufactured by the torsion beam manufacturing method of a vehicle suspension system according to an embodiment of the present invention.

Hereinafter, various preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art, and the following examples may be modified into various other forms, and the scope of the present invention is as follows. It is not limited to the examples. Rather, these embodiments are provided to make the present disclosure more faithful and complete and to fully convey the spirit of the present invention to those skilled in the art. Additionally, the thickness and size of each layer in the drawings are exaggerated for convenience and clarity of explanation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will now be described with reference to drawings that schematically show ideal embodiments of the present invention. In the drawings, variations of the depicted shape may be expected, for example, depending on manufacturing technology and/or tolerances. Accordingly, embodiments of the present invention should not be construed as being limited to the specific shape of the area shown in this specification, but should include, for example, changes in shape resulting from manufacturing.

1 is a process flowchart sequentially showing a method of manufacturing a torsion beam of a vehicle suspension system according to an embodiment of the present invention, and FIGS. 2 to 5 show each manufacturing process of a torsion beam of a vehicle suspension system according to the process flowchart of FIG. 1. These are perspective views that schematically represent . And, Figure 6 is an image comparing the results of analyzing the torsional load stress distribution of the torsion beam 100 of the conventional vehicle suspension system and the torsion beam 100 of the vehicle suspension system of the present invention, and Figure 7 is an embodiment of the present invention. This is an image showing the actual product of the vehicle suspension system (1000) manufactured by the torsion beam manufacturing method of the vehicle suspension system according to .

First, as shown in FIG. 1, the method of manufacturing a torsion beam of a vehicle suspension system according to an embodiment of the present invention is for manufacturing a torsion beam 100 having a “V”-shaped closed cross-section in at least some sections. A torsion beam manufacturing method for a vehicle suspension system may largely include a lower plate forming step (S100), an upper plate forming step (S200), an assembling step (S300), and a welding step (S400).

As shown in FIGS. 1 and 2, in the lower plate forming step (S100), the first plate P1 having a first thickness is formed into the lower plate 10 having a shape corresponding to the lower portion of the torsion beam 100. can do.

For example, in the lower plate forming step (S100), the lower plate 10 may form the inner bent portion (112 in Fig. 5) and the earing portion (120 in Fig. 5) of the curved portion (110 in Fig. 5) of the torsion beam 100. In order to do this, the first plate (P1) can be formed by bending to have a “W” shaped cross section.

At this time, in the lower plate forming step (S100), the lower plate 10, which is bent and molded to have a “W”-shaped cross section, is press molded at least twice, as shown in (a) and (b) of FIG. 2. Thus, the bending portion can be sequentially bent and formed at least twice.

In this way, by sequentially dividing the bending part at least two times and performing bending molding, plastic deformation occurs intensively in the bending part at once, which can have the effect of preventing molding cracks from occurring during the bending molding process.

In addition, in the lower plate forming step (S100), both sides of the first plate (P1), which is bent and formed to have a “W”-shaped cross section, can be stably held by the holding pad (not shown) of the forming mold. A pair of first flange portions (F1) of a planar shape may be formed on both sides of the molded area that is formed into a W” shape.

Subsequently, as shown in FIGS. 1 and 3, in the upper plate forming step (S200), a second plate P2 having a second thickness different from the first thickness is formed corresponding to the upper portion of the torsion beam 100. It can be molded into a shaped top plate (20).

For example, in the upper plate forming step (S200), the second plate P2 is formed into a “V” shape so that the upper plate 20 forms the outer bent portion 111 of the curved portion (110 in FIG. 5) of the torsion beam 100. It can be bent and formed to have a square cross-section.

At this time, in the upper plate forming step (S200), the upper plate 20, which is bent and molded to have a “V”-shaped cross section, is press molded at least twice, as shown in (a) and (b) of FIG. 3. Thus, the bending portion can be sequentially bent and formed at least twice.

In this way, like the lower plate 10 described above, the upper plate 20 is also bent and molded by sequentially dividing the bending portion into at least two parts, so that plastic deformation occurs intensively in the bending portion at once, resulting in forming cracks during the bending molding process. It can have the effect of preventing this from happening.

In addition, in the upper plate forming step (S200), both sides of the second plate (P2), which is bent and formed to have a “V”-shaped cross section, can be stably held by the holding pad (not shown) of the forming mold. A pair of second flange portions (F2) in a planar shape may be formed on both sides of the V”-shaped molded portion.

The first thickness of the first plate P1 formed into the lower plate 10 in the lower plate forming step S100 and the second plate P2 formed into the upper plate 20 in the upper plate forming step S200 The second thickness is the portion where stress concentration occurs and the portion where stress concentration does not occur of the torsion beam 100, which is manufactured by welding the lower plate 10 and the upper plate 20 through the assembly step (S300) and the welding step (S400) to be described later. So that they can be formed to different thicknesses, they can be formed to different thicknesses.

For example, the first thickness of the first plate P1 formed into the lower plate 10 in the lower plate forming step S100 is that of the second plate P2 formed into the upper plate 20 in the upper plate forming step S200. It is formed to be thicker than the second thickness, and the difference in thickness may be at least 0.5 mm or more.

Subsequently, as shown in FIGS. 1 and 4, in the assembly step (S300), the upper plate 20 can be assembled on the upper side of the lower plate 10.

For example, in the assembly step (S300), the “W” of the lower plate 10 can be held on both sides of the first plate (P1), which is bent and molded to have a “W”-shaped cross section in the lower plate forming step (S100). In the first flange portion cutting step (S310) of cutting a pair of first flange portions (F1) formed on both sides of the shaped cross section, and the top plate forming step (S200), the top plate is bent and formed to have a “V” shaped cross section. A second flange portion cutting step (S320) of cutting a pair of second flange portions (F2) formed on both sides of the “V”-shaped cross section of the upper plate (20) so that both sides of the second plate (P2) can be held. ) and a seating step in which the upper plate 20, bent and molded to have a “V” shaped cross section, is flipped and placed in a “∧” shape on the upper side of the lower plate 10, which has been bent and molded to have a “W” shaped cross section. (S330) may proceed in this order.

At this time, in the second flange portion cutting step (S320), the pair of second flange portions (F2) are shorter than the pair of first flange portions (F1) cut in the first flange portion cutting step (S310). It may be desirable to cut to length.

Accordingly. Finally, as shown in FIG. 5, the assembly step (S300) further bends the pair of first flange portions (F1) inward through the bending step (S340), thereby forming the pair of lower plate 10. The first flange portion F1 may cover at least a portion of the inclined surface 21 of the upper plate 20 so that the ends of the pair of first flange portions F1 and the inclined surface of the upper plate 20 come into contact.

Subsequently, as shown in FIGS. 1 and 5, in the welding step (S400), the connection portion of the lower plate 10 and the upper plate 20 is welded to form the torsion beam 100.

For example, in the welding step (S400), the contact portion of the end of the pair of first flange portions F1 of the lower plate 10 and the inclined surface 21 of the upper plate 20 are welded by arc welding, thereby forming the lower plate 10. ) and the upper plate 20 can be combined to form a torsion beam 100. Accordingly, a welding line W is formed along the contact portion between the end portions of the pair of first flange portions F1 formed long along the longitudinal direction of the torsion beam 100 and the inclined surface 21 of the upper plate 20. It can be formed long.

Here, the lower plate 10 and the upper plate 20 are welded and joined by arc welding, but this is not necessarily limited to this, and TIG welding or friction stir welding is used as an example. Any welding process that can firmly join the lower plate 10 and the upper plate 20 can be used.

Accordingly, as shown in FIG. 5, the lower plate 10 is formed of a first plate P1 of a first thickness t1 and a second plate of a second thickness t2 thinner than the first thickness t1. The torsion beam 100, which is formed by joining the upper plate 20 molded as (P2) by welding, has the outer bent portion 111 of the curved portion 110 with a second thickness based on the “V”-shaped closed cross-section. It is formed as a portion of the upper plate 20 having a portion, and the inner bent portion 112 of the curved portion 110 and the earring portion 120 at both ends are formed as a portion of the lower plate 10 having a first thickness t1, thereby forming a specific section. It may be formed as a torsion beam 100 having closed cross-sections of different thicknesses.

For example, as shown in the simulation result analyzing the torsional load stress distribution in Figure 6, the torsion beam formed by hydroforming the conventional pipe in (a) has a V"-shaped closed cross-section when the torsional load is applied. Based on , it was found that stress distribution was concentrated on the inner bent portion 112 of the curved portion 110 and the earring portion 120 at both ends. In this way, stress concentration may occur in the earring portion 120, which may cause durability quality problems, such as easily causing breakage in the earring portion 120.

However, as shown in the simulation result of the torsion beam 100 of the present invention in Figure 6 (b), the lower plate 10 and the upper plate 20 are joined so that the upper and lower plates can have different thicknesses. In the case of the torsion beam 100, when a torsional load is applied, the inner bent portion 112 of the curved portion 110 and the earring portions 120 at both ends are formed with a relatively thick thickness based on the “V”-shaped closed cross-section. As a result, it was confirmed that the stress concentration in the earring portion 120 was significantly lowered, thereby significantly reducing the possibility of durability quality problems.

In this way, according to the method of manufacturing a torsion beam of a vehicle suspension system according to an embodiment of the present invention, as shown in FIG. 7, the durable weak part where a large torsional moment can occur has a large thickness and does not affect the torsional moment. The almost missing part is made by manufacturing a torsion beam 100 with a relatively thin thickness and then attaching trailing arms 200 that can be connected to the wheels and body of the vehicle on both sides of the torsion beam 100. , vehicle suspension device 1000 can be manufactured.

Therefore, according to the method of manufacturing a torsion beam for a vehicle suspension system and the vehicle suspension device according to an embodiment of the present invention, the upper and lower parts of the closed cross-section are separated so that the thickness and shape can be changed, and the upper plate is placed in a place where durability is not affected. (20) and the lower plate (10) are separated and formed into shapes, and then joined through welding. By doing this, plastic deformation occurs at the durability weak part of the lower part of the torsion beam where a large torsional moment can occur and plastic deformation occurs during forming, which easily causes molding cracks. The earring portion 120, where stress concentration can occur due to the torsional load imposed even after product molding, has a thick thickness, and the portion that has little effect on the torsional moment at the upper end is a torsion beam 100 with a relatively thin thickness. It can be manufactured.

In this way, it is possible to produce a tubular beam type torsion beam through press molding without manufacturing, and by producing the upper and lower plates separately through press molding, the thickness can be different from each other, and the steel type can also be designed differently. , Since the upper plate 20 and the lower plate 10 are molded differently, it can have an advantageous effect in terms of formability compared to the conventional method of manufacturing a torsion beam by molding using a single blank.

In addition, since there is an advantage in that the width of the panel can be made different when molding using the press method, molding is possible even when manufacturing variable cross-section CTBA tubular beams, and the durability of the part is improved and lightweight by reinforcing the thickness of the weak durability part of the torsion beam. A vehicle suspension device 1000 that can simultaneously achieve can be implemented.

The present invention has been described with reference to the embodiments shown in the drawings, but these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true scope of technical protection of the present invention should be determined by the technical spirit of the attached patent claims.

10: Bottom plate
20: Top plate
21: slope
100: Torsion beam
110: curved portion
111: Outer bending part
112: medial bending part
120: Earring part
200: Trailing arm
1000: Vehicle suspension system
P1: first plate
P2: Second plate
F1: A pair of first flange portions
F2: A pair of second flange portions
W: welding line

Claims (13)

In the torsion beam manufacturing method of a vehicle suspension system for manufacturing a torsion beam having a “V”-shaped closed cross-section in at least some sections,
A lower plate forming step of forming a first plate having a first thickness into a lower plate of a shape corresponding to the lower portion of the torsion beam;
A top plate forming step of forming a second plate having a second thickness different from the first thickness into a top plate of a shape corresponding to the upper portion of the torsion beam;
An assembly step of assembling the upper plate on the upper side of the lower plate; and
A welding step of welding a connection portion of the lower plate and the upper plate to form the torsion beam;
A torsion beam manufacturing method for a vehicle suspension system, including a. According to claim 1,
The first thickness of the first plate is,
A method of manufacturing a torsion beam for a vehicle suspension system, wherein the second plate is formed to a thickness greater than the second thickness. According to claim 2,
The first thickness and the second thickness are,
A method of manufacturing a torsion beam for a vehicle suspension system where the difference in thickness is at least 0.5 mm. According to claim 2,
The torsion beam is,
Based on a “V”-shaped closed cross-section, the outer bent portion of the curved portion is formed by the upper plate portion having the second thickness, and the inner bent portion of the curved portion and the earring portions at both ends are formed with the lower plate having the first thickness. Method for manufacturing a torsion beam of a vehicle suspension system, formed from parts. According to claim 4,
In the lower plate forming step,
A torsion beam of a vehicle suspension system in which the first plate is bent and formed to have a “W”-shaped cross section so that the lower plate forms the inner bent portion and the earring portion of the curved portion of the torsion beam. Manufacturing method. According to claim 5,
In the lower plate forming step,
A method of manufacturing a torsion beam for a vehicle suspension system, wherein the lower plate, which is bent and molded to have a “W”-shaped cross section, is sequentially bent and molded at least twice at least twice by press molding at least twice. According to claim 5,
In the upper plate forming step,
A method of manufacturing a torsion beam for a vehicle suspension system, wherein the second plate is bent and formed to have a “V” shaped cross section so that the upper plate forms the outer bent portion of the curved portion of the torsion beam. According to claim 7,
In the upper plate forming step,
A method of manufacturing a torsion beam for a vehicle suspension system, wherein the upper plate, which is bent and molded to have a “V”-shaped cross section, is sequentially bent and molded at least twice at least twice by press molding at least twice. According to claim 7,
The assembly step is,
A pair of first flanges formed on both sides of the “W” shaped cross section of the lower plate to be able to hold both sides of the first plate that is bent and formed to have a “W” shaped cross section in the lower plate forming step. Cutting the first flange portion;
In the upper plate forming step, a pair of second flanges formed on both sides of the “V” shaped cross section of the upper plate are provided to hold both sides of the second plate that is bent and formed to have a “V” shaped cross section. A second flange portion cutting step; and
A seating step of flipping the upper plate, which has been bent and molded to have a “V” shaped cross section, into a “∧” shape and placing it on the upper side of the lower plate, which has been bent and molded to have a “W” shaped cross section;
A torsion beam manufacturing method for a vehicle suspension system, including a. According to clause 9,
The assembly step is,
After the seating step, the pair of first flange portions of the lower plate covers at least a portion of the inclined surface of the upper plate so that the ends of the pair of first flange portions and the inclined surface of the upper plate can come into contact. A bending step of further bending the first flange portion of the pair inward;
A method of manufacturing a torsion beam of a vehicle suspension system, further comprising: According to clause 9,
In the second flange portion cutting step,
The method of manufacturing a torsion beam for a vehicle suspension device, wherein the pair of second flange portions are cut to a shorter length than the pair of first flange portions cut in the first flange portion cutting step. According to claim 10,
In the welding step,
A method of manufacturing a torsion beam for a vehicle suspension system, wherein a contact portion of the end of the pair of first flange portions and the inclined surface of the upper plate is welded. A torsion beam for a vehicle suspension manufactured by the method for manufacturing a torsion beam for a vehicle suspension according to any one of claims 1 to 12;
Including, a suspension system for a vehicle.

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