CN112776929B

CN112776929B - Vehicle swing arm

Info

Publication number: CN112776929B
Application number: CN202011233571.1A
Authority: CN
Inventors: 伊什瓦·拉杰瓦尼; 杰夫什·普拉森
Original assignee: Shangyinuo Motorcycle Co ltd
Current assignee: Shangyinuo Motorcycle Co ltd
Priority date: 2019-11-06
Filing date: 2020-11-06
Publication date: 2023-04-07
Anticipated expiration: 2040-11-06
Also published as: CO2020013916A1; CN112776929A

Abstract

A swing arm (220) of a vehicle (10) includes: a first arm (222), a second arm (224), and a bridge member (140). The first arm (222) has an upper support wall (230), a lower support wall (232), an inboard support wall (234), and at least one set of first arm rib members (236 and 238). The second arm (224) has an upper support wall (230 a), a lower support wall (232 a), an inner support wall (234 a), at least one set of second arm rib members (236 a and 238 a). The bridge member (140) has a first sidewall (142) and a second sidewall (144) spaced apart from each other. At least one of the first side wall (142) and the second side wall (144) includes at least one set of bridge rib members (240 and 240 a), and the at least one set of bridge rib members (240 and 240 a) extends outward in a width direction of the vehicle (10).

Description

Vehicle swing arm

Technical Field

The present invention relates to a two-wheeled vehicle, and more particularly to a swing arm of a two-wheeled vehicle.

Background

Vehicles, particularly vehicles configured for riding, such as scooters, motorcycles, three-wheeled vehicles, and four-wheeled vehicles (e.g., all-terrain vehicles), include the internal combustion engine and body frame of the vehicle. The power generated by the internal combustion engine is transmitted to the wheels and other auxiliary components of the vehicle. The internal combustion engine is carried by the frame of the vehicle.

Typically, the frame includes a swing arm that rotatably supports the rear wheel. In addition, the swing arm serves as a support member for one or more rear suspensions and other vehicle components. The swing arm is generally formed of a left arm and a right arm to which an axle of the rear wheel is attached at the rear side, and the front side of the swing arm is hingably supported on the vehicle body frame. The cross member is connected to the left and right arms of the swing arm. The cross member is provided with a bracket member extending upward from the cross member, which supports a lower portion of a rear suspension of the vehicle. Each of the left arm, the right arm, and the cross member includes a set of rib members.

In a one-piece die cast swing arm, a set of rib members are formed at the left and right arms to form the swing arm. It is always desirable to keep the swing arm lightweight while withstanding different loads. However, the length of the rib member requires a larger draft angle, resulting in a higher weight of the rib member of the swing arm and a lower level of porosity, which is undesirable.

Disclosure of Invention

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key or critical features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

In one aspect of the invention, a vehicle includes a swing arm having a frame. The swing arm includes a first arm, a second arm, and a bridge member. The first arm has an upper support wall, a lower support wall, an inner support wall connecting the upper support wall and the lower support wall, and at least one set of first arm rib members. The second arm has an upper support wall, a lower support wall, an inner support wall connecting the upper support wall and the lower support wall, and at least one set of second arm rib members. The bridge member has a first sidewall and a second sidewall. The first and second side walls are spaced apart from each other in the vehicle width direction, and at least one of the first and second side walls includes at least one set of bridge rib members extending outward in the vehicle width direction.

In one embodiment, the first arm has a first arm first set of rib members and a first arm second set of rib members. The second arm has a second arm first set of rib members and a second arm second set of rib members.

In one embodiment, the first side wall has a first set of bridge rib members and the second side wall has a second set of bridge rib members.

In one embodiment, a first set of bridge rib members extends from the first side wall in a direction W1 along the width of the vehicle. The second set of bridge rib members extends from the second side wall in a direction W2 along the width of the vehicle.

In one embodiment, the swing arm has a first set of bridge rib members and a second set of bridge rib members having a draft angle less than or equal to 3 degrees.

In one embodiment, the swing arm has a first set of bridge rib members and a second set of bridge rib members having a length along a width of the vehicle that is less than or equal to 70 millimeters.

In one embodiment, the swing arm has a bridge member. The bridge member further includes a third set of bridge rib members and a bottom wall such that the third set of bridge rib members extend outwardly from the bottom wall.

In one embodiment, the swing arm has a third set of bridge rib members extending upwardly from the bottom wall.

In one embodiment, the swing arm has a third set of bridge rib members extending downwardly from the bottom wall.

One advantage of the present invention is that because the first set of bridge rib members extend outwardly from the first side wall, the second set of bridge rib members extend outwardly from the second side wall, and the third set of bridge rib members extend outwardly from the bottom wall. This configuration minimizes the length of the rib member, thus reducing the draft angle, and also reduces weight by saving material. This makes the swing arm lighter in weight.

In one embodiment, the swing arm has a third set of bridge rib members engaged with the first and second side walls.

In one embodiment, the swing arm has a cover member that covers the bridge member to close a space inside the bridge member.

An advantage of the invention is that since the cover member covers the bridge member to close the space inside the bridge member, this avoids any dust, dirt and water accumulation inside the bridge member, and furthermore, the space inside the bridge member may be used as utility space.

In one embodiment, a vehicle includes a swing arm having a frame. The swing arm includes a first arm, a second arm, and a bridge member. The first arm has an upper support wall, a lower support wall, an inner support wall connecting the upper support wall and the lower support wall, and at least one set of first arm rib members. The second arm has an upper support wall, a lower support wall, an inner support wall connecting the upper support wall and the lower support wall, and at least one set of second arm rib members. The bridge member has a first sidewall, a second sidewall, a first set of bridge rib members, a second set of bridge rib members, and a third set of bridge rib members. At least one of the first set of bridge rib members and the second set of bridge rib members extends in the vehicle width direction, and the third set of bridge rib members extends vertically in the vehicle height direction.

Drawings

The invention itself, together with further features and attendant advantages, will be best understood by reference to the following detailed description, taken in conjunction with the accompanying drawings. One or more embodiments of the present invention will now be described, by way of example only, with like reference numerals representing like elements, wherein:

FIG. 1 illustrates a side view of an exemplary two-wheeled vehicle according to one embodiment of the present invention;

FIG. 2 illustrates a perspective view of a frame of an exemplary two-wheeled vehicle according to one embodiment of the present invention;

FIG. 3 illustrates a perspective view of a swing arm of an exemplary two-wheeled vehicle, according to one embodiment of the present invention;

FIG. 4 illustrates another perspective view of a swing arm of an exemplary two-wheeled vehicle, in accordance with one embodiment of the present invention;

FIG. 5 illustrates another perspective view of a swing arm of an exemplary two-wheeled vehicle according to one embodiment of the present invention;

FIG. 6A illustrates a side view of a swing arm of an exemplary two-wheeled vehicle, according to one embodiment of the present invention;

FIG. 6B illustrates a cross-sectional view of a swing arm of an exemplary two-wheeled vehicle, according to one embodiment of the present invention;

FIG. 7A illustrates a cross-sectional view of a swing arm of an exemplary two-wheeled vehicle, according to one embodiment of the present invention;

FIG. 7B illustrates a bottom view of a swing arm of an exemplary two-wheeled vehicle, according to an embodiment of the present invention;

FIG. 8A illustrates a perspective view of a swing arm of an exemplary two-wheeled vehicle according to another embodiment of the present invention; and

fig. 8B shows a cross-sectional view of a swing arm of an exemplary two-wheeled vehicle according to another embodiment of the present invention.

The drawings referred to in this description should not be understood as being drawn to scale unless specifically noted, and are merely exemplary in nature.

Detailed Description

While the invention is susceptible to various modifications and alternative forms, embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an arrangement, structure, or method that comprises a list of elements or steps does not include only those elements or steps, but may include other elements or steps not expressly listed or inherent to such arrangement, structure, or method. In other words, without further constraints, one or more elements beginning with 'include 8230', '8230;' do not preclude the presence of other elements or other elements in the system or device.

For a better understanding of the present invention, reference will now be made to the embodiments illustrated in the drawings and described below, in addition to the accompanying figures in which like reference numerals are used to identify like parts in the various views.

However, while the invention is illustrated in the context of a vehicle, the swing arm and aspects and features thereof may also be used with other types of vehicles. Throughout the specification, the terms "vehicle", "two-wheeled vehicle" and "motorcycle" have been used interchangeably. The term "vehicle" includes vehicles such as motorcycles, scooters, bicycles, scooters, scooter-type vehicles, all-terrain vehicles (ATVs), and the like.

The terms "front/forward", "rear/rearward", "up/above/top", "down/below/down, bottom", "left/left", "right/right" used herein denote directions as seen from the straddle-type vehicle driver, and these directions are indicated by arrows Fr, rr, U, lr, L, R in the drawings.

Referring to fig. 1, a vehicle (10) according to an embodiment of the present invention is shown. The vehicle (10) referred to herein is embodied as a two-wheeled motorcycle. Alternatively, without limiting the scope of the invention, the vehicle (10) may be embodied as any other cycling vehicle, such as a scooter, a three-wheeled vehicle, an All Terrain Vehicle (ATV), and the like.

The vehicle (10) includes one or more body parts, such as a frame (12), a handlebar (14), a front wheel (16), a rear wheel (18), an engine (200), a headlight (22), and a fuel tank (24). The frame (12) supports an engine (200) in a middle portion of the vehicle (10). In the illustrated embodiment, the engine (200) provides the necessary power required to drive the rear wheels (18) of the vehicle (10). Alternatively, without limiting the scope of the invention, the engine (200) may provide the necessary power to drive the front wheels (16), or to drive both the front wheels (16) and the rear wheels (18). The rear wheel (18) is connected to the engine (200) via a transmission (not numbered). The fuel tank (24) provides the necessary fuel to the engine (200) to generate power within the vehicle (10).

Referring to fig. 2, the vehicle (10) includes a frame (12). The frame (12) is formed by integrally joining a plurality of steel members or the like by welding or the like. In the illustrated embodiment, a frame (12) having a particular configuration is disclosed. Alternatively, without limiting the scope of the invention, the frame (12) may have a different body frame configuration normally associated with motorcycles.

The frame (12) includes a head pipe (124), a lower frame member (125), and an upper frame member (126). The upper frame member (126) extends downward and rearward in the longitudinal direction of the vehicle (10) from the head pipe (124). A pivot plate (129) is disposed on a rear portion of the upper frame member (126). The upper frame member (126) supports the fuel tank (114). The lower frame member (125) extends downward and rearward in the longitudinal direction of the vehicle (10) from the head pipe (124), and is disposed below the upper frame member (126). The lower frame member (125) supports the power unit (110) (shown in fig. 1). The head tube (124) is a cylindrical member that supports the steering assembly (104) and the front wheels (16). A steering shaft (not shown) is rotatably supported on the head pipe (124). The front fork (117) is inclined at substantially the same inclination angle as that of the head pipe (124).

The frame (12) includes a left seat track member (123) and a right seat track member (127). Left and right seat rail members (123, 127) extend rearwardly from the upper frame member (126). The left seat rail member (123) and the right seat rail member (127) support a seat (116) of the vehicle (10). The lower frame member (125) and a pivot plate (129) disposed at the rear of the upper frame member (126) support an engine (112) of the vehicle (10).

The frame (12) includes a left sub-frame member (131) and a right sub-frame member (133). A left subframe member (131) extends between the left seat track member (123) and the pivot plate (129). A right subframe member (133) extends between the right seat track member (127) and the pivot plate (129). The left sub frame member (131) and the right sub frame member (133) provide support for the left seat track member (123) and the right seat track member (127), respectively.

As shown in fig. 3, 4, and 5, the vehicle (10) includes a swing arm (220). A swing arm (220) is operatively coupled to the frame (12). The swing arm (220) rotatably supports the rear wheel (18). The swing arm (220) includes a first arm (222) and a second arm (224). The rear wheel (18) is pivotally supported between a first arm (222) and a second arm (224) of the swing arm (220). The vehicle (10) includes a deceleration system (not shown). The deceleration system provides braking forces to the front wheels (16) and the rear wheels (18) for decelerating or stopping the vehicle (10). Furthermore, without limiting the scope of the invention, the rear of the vehicle (10) may include tail lights, suspension systems, rear handlebars, etc.

The first arm (222) and the second arm (224) support an axle (not shown) of the rear wheel (18). In the illustrated embodiment, the swing arm (220) is a dual support type swing arm in which the rear wheel (18) is supported on both the left and right sides of its axle. The swing arm (220) can mount one or more shock absorbers (not shown).

The first arm (222) includes three support walls and a set of rib members. In particular, the first arm (222) comprises: an upper support wall (230) (shown in fig. 4), a lower support wall (232), and an inner support wall (234) connecting the upper support wall (230) and the lower support wall (232). The upper support wall (230), the lower support wall (232), and the inner support wall (234) connecting the upper support wall (230) and the lower support wall (232) form a C-shaped cross section.

In one embodiment, the upper support wall (230), the lower support wall (232) and the inner support wall (234) connecting the upper support wall (230) and the lower support wall (232) form a first arm (222), which has an opening or cavity in the first arm (222) in its longitudinal direction. In one embodiment, an upper support wall (230), a lower support wall (232), and an inner support wall (234) connecting the upper support wall (230) and the lower support wall (232) form an opening on the first arm (222) toward the left side of the vehicle (10).

The first arm (222) further includes a first arm first set rib member (236) and a first arm second set rib member (238), as shown in fig. 7B, the first arm first set rib member (236) extending along the width direction W1 of the first arm (222). The first arm second set rib members (238) also extend along the width direction W1 of the first arm (222). In one embodiment, a first arm first set of rib members (236) and a first arm second set of rib members (238) extend from an inner surface of the inboard support wall (234) along the upper support wall (230), with the lower support wall (232) facing an opening in the first arm (222) toward the left side of the vehicle (10).

Likewise, the second arm (224) includes three support walls, i.e., an upper support wall (230 a), a lower support wall (232 a), and an inner side support wall (234 a) connecting the upper support wall (230 a) and the lower support wall (232 a). The upper support wall (230 a), the lower support wall (232 a), and the inner support wall (234 a) connecting the upper support wall (230 a) and the lower support wall (232 a) form a C-shaped cross section.

In one embodiment, the upper support wall (230 a), the lower support wall (232 a), and the inner support wall (234 a) connecting the upper support wall (230 a) and the lower support wall (232 a) form the second arm (224), which has an opening or cavity in the second arm (224) in its longitudinal direction. In one embodiment, the upper support wall (230 a), the lower support wall (232 a), and the inner support wall (234 a) connecting the upper support wall (230 a) and the lower support wall (232 a) form an opening in the second wall (224) toward the right side of the vehicle (10).

The second arm (224) further includes a second arm first set of rib members (236 a) and a second arm second set of rib members (238 a). The second arm first set rib member (236 a) extends in the width direction W2 of the second arm (224). The second arm second set rib member (238 a) also extends in the width direction W2 of the second arm (224). In one embodiment, a second arm first set rib member (236 a) and a second arm second set rib member (238 a) extend from an inner surface of the inboard support wall (234 a) along the upper support wall (230 a), and the lower support wall (232 a) is directed toward an opening in the second arm (224) that is directed toward the right side of the vehicle (10).

The swing arm (220) includes a bridge member (140). The bridging member (140) is a hollow member disposed between the first arm (222) and the second arm (224), the bridging member (140) connecting the two arms together in side-by-side relationship with each other.

As shown in fig. 6A, 6B, 7A, and 7B, the bridge member (140) includes a first side wall (142), a second side wall (144), a first set of bridge rib members (240), a second set of bridge rib members (240 a), and a third set of bridge rib members (146), and a bottom wall (148). The bridge member (140) engages the second arm (224) and the first arm (222) with each other. The bridge member (140) has a bottom wall (148), the bottom wall (148) joining the first side wall (142) and the second side wall (144).

The first side wall (142) and the second side wall (144) are spaced apart from each other in the vehicle width direction. A first set of bridge rib members (240) extend from the first side wall (142) in a direction W1 along the width of the vehicle (10). The second set of bridge rib members (240 a) extend from the second side wall (144) in a direction W2 along the width of the vehicle (10).

A third set of bridge rib members (146) extend outwardly from the bottom wall (148). Similarly, the first side wall (142) and the second side wall (144) extend outwardly from a peripheral edge portion of the bottom wall (148). In one embodiment, the first side wall (142) and the second side wall (144) extend perpendicularly outward from a peripheral edge portion of the bottom wall (148). In an alternative embodiment, the first and second side walls (142, 144) extend outwardly from a peripheral edge portion of the bottom wall (148) at a predetermined angle relative to the bottom wall (148).

In one embodiment, a third set of bridge rib members (146) extends downwardly from the bottom wall (148). In another embodiment, a third set of bridge rib members (146) extends upwardly from the bottom wall (148).

As shown in fig. 7A and 7B, the first set of bridge rib members (240) and the second set of bridge rib members (240 a) extend from the bridge member (140). More specifically, a first set of bridge rib members (240) extend from a first side wall (142) of the bridge member (140). In the same manner, a second set of bridge rib members (240 a) extend from the second side wall (144) of the bridge member (140).

In one embodiment, a first set of bridge rib members (240) extends from a first sidewall (142) of a bridge member (140) such that a length of each rib member is less than or equal to a predetermined length and a draft angle is less than or equal to a predetermined draft angle. In one embodiment, a first set of bridge rib members (240) extends from the first side wall (142) of the bridge member (140) such that each rib member has a length of about 70 millimeters. Further, in such an embodiment, each rib member of the first set of bridge rib members (240) has a draft angle of about 3 degrees.

In one embodiment, a second set of bridge rib members (240 a) extends from the second side wall (144) of the bridge member (140) such that the length of each rib member is less than or equal to a predetermined length and the draft angle is less than or equal to a predetermined draft angle. In one embodiment, a second set of bridge rib members (240 a) extend from the second side wall (144) of the bridge member (140), which results in a length of each rib member of about 70 millimeters. Further, in such an embodiment, each rib member of the second set of bridge rib members (240 a) has a draft angle of about 3 degrees.

The swing arm (220), i.e., all of its various parts, i.e., the first arm (222), the second arm (224), and the bridge member (140), are formed by a casting process that requires the provision of draft angles at the various elements or parts of the swing arm (220). The positioning of the first set of bridge rib members (240) and the second set of bridge rib members (240 a) on the bridge member (140) ensures that the length of the rib members of each of the first set of bridge rib members (240) and the second set of bridge rib members (240 a) is maintained within predetermined limits. Thus, a first set of bridge rib members (240) extending from the first side wall (142) of the bridge member (140) and a second set of bridge rib members (240 a) extending from the second side wall (144) of the bridge member (140) allow for a smaller draft angle.

In one embodiment, a first set of bridge rib members (240) extending from a first sidewall (142) of the bridge member (140) and a second set of bridge rib members (240 a) extending from a second sidewall (144) of the bridge member (140) are allowed to have a draft angle of less than or equal to 3 degrees.

Fig. 8A and 8B illustrate another embodiment of a swing arm 220. The swing arm (220) includes a bridge member (140). The bridging member (140) is a hollow member disposed between the first arm (222) and the second arm (224), the bridging member (140) connecting the two arms together in side-by-side relationship to one another.

The bridge member (140) includes a first sidewall (142), a second sidewall (144), a third set of bridge rib members (146), and a bottom wall (148). The bridge member (140) engages the second arm (224) and the first arm (222) with each other. The bridge member (140) has a bottom wall (148), the bottom wall (148) joining the first side wall (142) and the second side wall (144).

A third set of bridge rib members (146) extend upwardly from the bottom wall (148). Also, a first side wall (142) and a second side wall (144) extend upwardly from a peripheral edge portion of the bottom wall (148). In one embodiment, the first and second side walls (142, 144) extend perpendicularly outward from a peripheral edge portion of the bottom wall (148). In an alternative embodiment, the first and second side walls (142, 144) extend outwardly from a peripheral edge portion of the bottom wall (148) at a predetermined angle relative to the bottom wall (148).

Since the swing arm (220) has a third set of bridge rib members (146) extending upwardly from the bottom wall (148), which may contain dust, dirt and water inside, the swing arm (220) has a cover member (300), the cover member (300) covering the third set of bridge rib members (146) at the bridge members (140). In one embodiment, the cover member (300) snaps over the bridge member (140). The cover member (300) covers the bridge member (140) to close a space inside the bridge member (140), which can be used as a utility space by a rider, and furthermore, protects the swing arm (220) from dust, dirt, and water accumulating inside the bridge member (140).

In view of the foregoing, a first set of bridge rib members (240) extends outwardly from the first side wall (142), a second set of bridge rib members (240 a) extends outwardly from the second side wall (144), and a third set of bridge rib members (146) extends outwardly from the bottom wall (148). This configuration minimizes the length of the rib member, thus reducing the draft angle, and in addition may reduce weight by saving material. This makes the swing arm lighter in weight.

The draft angle used in the rib member is less than or equal to 3 degrees, which enables the swing arm (220) to have a significantly reduced weight because less material is used to form the rib. The reduction in weight significantly reduces the cost associated with the swing arm (220). In addition, the present invention enables a swing arm (220) to have an improved level of porosity by allowing the lengths of the first set of bridge rib members (240) and the second set of bridge rib members (240 a) to be less than a predetermined length.

Although several embodiments of the present invention have been described above, it should be understood that the present invention is not limited to the above embodiments, and may be appropriately modified within the spirit and scope of the present invention.

While emphasis has been placed herein on particular features of the invention, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other modifications will be apparent to those skilled in the art from the disclosure herein, which is to be regarded as illustrative in nature and not as restrictive, of the invention or preferred embodiments.

Claims

1. A swing arm (220) of a vehicle (10) having a frame (12), the swing arm comprising:

a first arm (222), the first arm (222) having an upper support wall (230), a lower support wall (232), an inboard support wall (234) connecting the upper support wall (230) and the lower support wall (232), at least one set of first arm rib members (236 and 238);

a second arm (224) having an upper support wall (230 a), a lower support wall (232 a), an inner support wall (234 a) connecting the upper support wall (230 a) and the lower support wall (232 a), at least one set of second arm rib members (236 a and 238 a); and

a bridge member (140), wherein the bridge member (140) has a first side wall (142) and a second side wall (144), the first side wall (142) and the second side wall (144) being spaced apart from each other in a vehicle width direction, and wherein at least one of the first side wall (142) and the second side wall (144) includes at least one set of bridge rib members (240 and 240 a), the at least one set of bridge rib members (240 and 240 a) extending outward in the width direction of the vehicle (10),

wherein the bridge member (140) further comprises a third set of bridge rib members (146) and a bottom wall (148), such that the third set of bridge rib members (146) extend from the bottom wall (148).

2. The swing arm (220) of claim 1 wherein the first arm (222) has a first arm first set of rib members (236) and a first arm second set of rib members (238); and the second arm (224) has a second arm first set rib member (236 a) and a second arm second set rib member (238 a).

3. The swing arm (220) of claim 1, wherein the first side wall (142) comprises a first set of bridge rib members (240) and the second side wall (144) comprises a second set of bridge rib members (240 a).

4. The swing arm (220) of claim 3, wherein the first set of bridge rib members (240) extend from the first side wall (142) in a direction W1 along a width of the vehicle (10), and the second set of bridge rib members (240 a) extend from the second side wall (144) in a direction W2 along the width of the vehicle (10).

5. The swing arm (220) of claim 3, wherein the first set of bridge rib members (240) and the second set of bridge rib members (240 a) have a draft angle less than or equal to 3 degrees.

6. The swing arm (220) of claim 3, wherein the first set of bridge rib members (240) and the second set of bridge rib members (240 a) have a length along a width of the vehicle (10) that is less than or equal to 70 millimeters.

7. The swing arm (220) of claim 1 wherein the third set of bridge rib members (146) extend upwardly from the bottom wall (148).

8. The swing arm (220) of claim 1, wherein the third set of bridge rib members (146) extend downwardly from the bottom wall (148).

9. The swing arm (220) of claim 1 wherein the third set of bridge rib members (146) engage the first and second side walls (142, 144).

10. The swing arm (220) according to claim 1, wherein a cover member (300) covers the bridge member (140) to close a space inside the bridge member (140).

11. A swing arm (220) of a vehicle (10) having a frame (12), the swing arm comprising:

a second arm (224), the second arm (224) having an upper support wall (230 a), a lower support wall (232 a), an inner support wall (234 a) connecting the upper support wall (230 a) and the lower support wall (232 a), at least one set of second arm rib members (236 a and 238 a); and

a bridge member (140), wherein the bridge member (140) has a first side wall (142), a second side wall (144), a first set of bridge rib members (240), a second set of bridge rib members (240 a), and a third set of bridge rib members (146), wherein at least one of the first set of bridge rib members (240) and the second set of bridge rib members (240 a) extends in a vehicle width direction, and the third set of bridge rib members (146) extends vertically in a vehicle height direction.