FRONT STRUCTURE OF VEHICLE BODY

Abstract: A front structure of a vehicle body includes a front frame which extends in the longitudinal direction of the vehicle body and is formed of an outer frame and an inner frame connected together to form a closed cross section. A dash­ board lower panel is disposed near the rear edge of the front frame to vertically extend, and a front floor extends rearward from the lower edge of the dashboard lower panel. A side sill is disposed on one side of the front floor at a height lower than the front frame, and a floor frame is disposed on the inner side of the side sill at a height lower than the front frame. The rear end portion of the front frame is connected to the side sill by way of a frame member and to the front end portion of the floor frame by way of another frame member.

Description: This invention relates to a front structure of a vehicle body having the features as stated in the first part of claim 1. In a front structure according to the prior art (JP-A 59-109468) a front frame extending in the longitudinal direction of the vehicle body is formed by connecting an outer frame and a channel-shaped inner frame to have a closed cross section. The rear end of the front frame is connected to the dashboard lower panel in order to ensure a sufficient strength and the suspension tower is disposed on the outer side of the front frame. Therefore the suspension tower is apt to be deformed due to external forces such as vibration and impacts transmitted from the suspension. Further, this front structure is not sufficient from the viewpoint of the rigidity of the vehicle body. A similar front structure of a vehicle is disclosed in US-A 37 91 472 which has the features stated in the first part of claim 1. The front frame of this known front structure is connected to the dashboard by its rear end and extends along the suspension tower. Since the single front frame is under a relatively heavy load, carrying the engine and transmitting vibrations and loads exerted by the wheels when running on a road, it is apt to be deformed in its portion near the suspension tower. Any deformation of the front frame thereby may be transmitted to this suspension tower and may impair the correct positioning of the wheel suspension. It is true, also in this known front structure there are provided means for strengthening. For this purpose the front frames are connected by means of torque boxes or connecting bridges to the side sills of the vehicle body. These torque boxes or connecting bridges, however, are not placed in the vicinity of the suspension tower but rather in the rear portion of the front frame near by the side sills. This means that deformations of the front frames occurring in the vicinity of the suspension tower cannot be prevented to an extent which is desirable. In view of the foregoing observations the primary object of the present invention is to provide an improved front structure of a vehicle which can ensure a sufficient rigidity of the vehicle body, in particular in that part of the front frame which is near the suspension tower so as to prevent the suspension tower to be affected by deformations of the front frame. These and further objects are achieved by a front frame structure having the features stated in the characterizing portion of claim 1. Embodiments of the front frame structure according to the invention are explained in context with the attached drawings. Figure 1 is a fragmentary perspective view of a front structure of a vehicle body in accordance with an embodiment of the present invention; Figure 2 is a cross-sectional view taken along line II-II in Figure 1; Figure 3 is a cross-sectional view taken along line III-III in Fig. 1; Figure 4 is a cross-sectional view taken along line IV-IV in Fig. 1; Figure 5 is a cross-sectional view taken along line V-V in Figure 1, Figure 6a is a cross-sectional view taken along line VIa-VIa in Figures 2 and 3, Figure 6b is a cross-sectional view taken along line VIb-VIb in Figures 2 and 3, Figure 6c is a cross-sectional view taken along line VIc-VIc in Figures 2 and 3, Figure 6d is a cross-sectional view taken along line VId-VId in Figures 2 and 3, Figure 7 is a view similar to Figure 3 but showing a modification of the embodiment of Figure 1, Figure 8 is a fragmentary perspective view of a front structure of a vehicle body in accordance with another embodiment of the present invention, Figure 9 is a cross-sectional view taken along line IX-IX in Figure 8, Figure 10 is a cross-sectional view taken along line X-X in Figure 8, Figure 11 is a cross-sectional view taken along line XI-XI in Figure 8, Figure 12 is a cross-sectional view taken along line XII-XII in Figure 8, Figure 13a is a cross-sectional view taken along line XIIIa-XIIIa in Figures 9 and 10, Figure 13b is a cross-sectional view taken along line XIIIb-XIIIb in Figures 9 and 10, Figure 13c is a cross-sectional view taken along line XIIIc-XIIIc in Figures 9 and 10, Figure 13d is a cross-sectional view taken along line XIIId-XIIId in Figures 9 and 10, Figure 14 is a view similar to Figure 10 but showing a modification of the embodiment of Figure 8, Figure 15 is a fragmentary perspective view of a front structure of a vehicle body in accordance with still another embodiment of the present invention, Figure 16 is a perspective view showing the lower gusset employed in the structure of Figure 15, Figure 17 is a cross-sectional view taken along line XVII-XVII in Figure 15, Figure 18 is a cross-sectional view taken along line XVIII-XVIII in Figure 15, Figure 19 is a cross-sectional view taken along line XIX-XIX in Figure 15, Figure 20 is a cross-sectional view taken along line XX-XX in Figure 15, Figure 21a is a cross-sectional view taken along line XXIa-XXIa in Figures 17 and 18, Figure 21b is a cross-sectional view taken along line XXIb-XXIb in Figures 17 and 18, Figure 21c is a cross-sectional view taken along line XXIc-XXIc in Figures 17 and 18, and Figure 21d is a cross-sectional view taken along line XXId-XXId in Figures 17 and 18. DESCRIPTION OF THE PREFERRED EMBODIMENTS In Figure 1, an outer frame 1 which is in the form of a vertical flat plate and an inner frame 2 which is a channel-like member are connected together to form a front frame 3 having a closed cross section. The front frame 3 extends in an engine room 4 in the longitudinal direction of the vehicle body. A dashboard lower panel 6 is provided on the rear side of the front frame 3 to vertically extend and separate the engine room 4 from a passenger compartment 5. The lower end portion of the dashboard lower panel 6 is bent obliquely rearward to form a rake surface portion 6a and is connected to a floor panel 7. A curved surface portion 6b and a projecting portion 6c are integrally provided on the outer side of the rake surface portion 6a of the dashboard lower panel 6. The curved surface portion 6b is formed as an extension of a wheel apron 9 formed on the rear side of a suspension tower 8, and is connected to an outer panel 10. The projecting portion 6c is formed on the lower side of the curved surface portion 6b to bulge rearward and is connected to a side sill 11. The outer frame 1 of the front frame 3 has a bent portion 1a which extends obliquely rearward from a portion of the front frame 3 immediately behind the suspension tower 8 toward the inner frame 2 across the closed cross-section front frame 3 and is connected to the inner peripheral surface of the inner frame 2. An outer rear frame 12 is connected to the outer surface of the outer frame 1 to extend rearward from a portion of the outer frame 1 on the front side of the bent portion 1a. The outer rear frame 12 extends below the outer portion of the dashboard lower panel 6 and the rear end 12a thereof is connected to the side sill 11 with the cross section of the outer rear frame 12 gradually changing toward the rear end 12a from a portion near the front surface of the dashboard lower panel 6. The outer rear frame 12 is bowed forward at the portion where the cross section changes and the periphery of the bowed portion is connected to the dashboard lower panel 6 or the floor panel 7 to form a closed cross section portion together with the curved surface portion 6b and the projecting portion 6c of the dashboard lower panel 6. The inner frame 2 of the front frame 3 extends in the longitudinal direction of the vehicle body and is connected to the dashboard lower panel 6 at the rear end thereof. To the lower surface of the rear end portion of the inner frame 2 is connected a front end portion of a channel-shaped joint frame 13 which is connected to the front surface of the rake surface portion 6a of the dashboard lower panel 6. The joint frame 13 is connected, at the lower surface of the floor panel 7, to a floor frame 7a connected to the floor panel 7 to extend in the longitudinal direction of the vehicle body. Figures 2 to 5 are cross-sectional views respectively taken along lines II-II, III-III, IV-IV and V-V in Figure 1, and Figures 6a to 6d are cross-sectional views respectively taken along lines VIa-VIa, VIb-VIb, VIc-VIc and VId-VId in Figures 2 and 3. The members are spot-welded at places indicated by X's in Figures 2 to 6. As can be understood from the description above and from the drawings, in the front structure of this embodiment, the outer frame 1 is bent inwardly at a portion near the rear side of the suspension tower 8 and is connected to the inner frame 2. Accordingly, a "node" is formed in the cross section of the front frame 3, and a sufficient strength against vibration and impacts transmitted from the suspension through the suspension tower 8 can be ensured irrespective of the fact that the outer rear frame 12 extends to the side side sill 11 without being connected to the vertical surface of the dashboard lower panel 6. Of course, the portion of the front frame 3 near the rear side of the suspension tower 8 can be further strengthened by directly connecting the rear end portion of the outer rear panel 12 as shown in Figure 7. Figures 8 to 13 show another embodiment of the present invention. In Figure 8, an outer frame 101 which is in the form of a vertical flat plate and an inner frame 102 which is a channel-like member are connected together to form a front frame 103 having a closed cross section. The front frame 103 extends in an engine room 104 in the longitudinal direction of the vehicle body. A dashboard lower panel 106 is provided on the rear side of the front frame 103 to vertically extend and separate the engine room 104 from a passenger compartment 105. The lower end portion of the dashboard lower panel 106 is bent obliquely rearward to form a rake surface portion 106a and is connected to a floor panel 107. A curved surface portion 106b and a projecting portion 106c are integrally provided on the outer side of the rake surface portion 106a of the dashboard lower panel 106. The curved surface portion 106b is formed as an extension of a wheel apron formed on the rear side of a suspension tower, and is connected to an outer panel 108. The projecting portion 106c is formed on the lower side of the curved surface portion 106b to bulge rearward and is connected to a side sill 109. The outer frame 101 of the front frame 103 extends below the outer portion of the dashboard lower panel 106 and the rear end 101a thereof is connected to the side sill 109 with the cross section of the outer frame 101 gradually changing toward the rear end 101a from a portion near the front surface of the dashboard lower panel 106. The outer frame 101 is bowed forward at the portion where the cross section changes and the periphery of the bowed portion is connected to the dashboard lower panel 106 or the floor panel 107 to form a closed cross section portion together with the curved surface portion 106b and the projecting portion 106c of the dashboard lower panel 106. The inner frame 102 of the front frame 103 has a bent portion 102b which extends obliquely rearward from a portion of the front frame 3 near the front surface of the dashboard lower panel 106 toward the outer fame 101 across the closed cross-section front frame 103 and is connected to the outer frame 101 at the distal end portion 102a thereof. A gusset 110 is provided on the inner frame 102 along the outer surface thereof to cover the bent portion 102b. The gusset 110 is connected to the inner frame 102 at the outer, inner, upper and lower sides thereof. The lower side of the gusset 110 extends below the dashboard lower panel 106 and the rear end portion 110a of the lower side of the gusset 110 is connected to a front end portion of a channel-shaped joint frame 111 which is connected to the front surface of the rake surface portion 106a of the dashboard lower panel 106. The lower side of the gusset 110 is gradually bowed downward from a portion near the front side of the dashboard lower panel 106 toward the rear end portion 110a to be smoothly merged into the joint frame 111. The joint frame 111 is connected, at the lower surface of the floor panel 107, to a floor frame 112 connected to the floor panel 107 to extend in the longitudinal direction of the vehicle body. Figures 9 to 12 are cross-sectional views respectively taken along lines IX-IX, X-X, XI-XI, and XII-XII in Figure 8, and Figures 13a to 13d are cross-sectional views respectively taken along lines XIIIa-XIIIa, XIIIb-XIIIb, XIIIc-XIIIc and XIIId-XIIId in Figures 9 and 10. The members are spot-welded at places indicated by X's in Figures 9 to 13. As can be understood from the description above and from the drawings, in the front structure of this embodiment, the rear portion of the inner frame 102 is bent outwardly and is connected to the outer frame 101 and the gusset 110 is provided to cover the bent portion 102b of the inner frame 102. Accordingly, a "node" is formed in the cross section of the front frame 103, and a sufficient strength can be ensured irrespective of the fact that the outer frame 101 extends to the side sill 109 without being connected to the vertical surface of the dashboard lower panel 106. Of course, the rear end portion of the front frame 103 can be further strengthened by directly connecting the rear end portion of the outer frame 101 as shown in Figure 14. Figures 15 to 20 show still another embodiment of the present invention. In Figure 15, an outer frame 201 which is in the form of a vertical flat plate and an inner frame 202 which is a channel-like member are connected together to form a front frame 203 having a closed cross section. The front frame 203 extends in an engine room 204 in the longitudinal direction of the vehicle body. A dashboard lower panel 206 is provided on the rear side of the front frame 203 to vertically extend and separate the engine room 204 from a passenger compartment 205. The lower end portion of the dashboard lower panel 206 is bent obliquely rearward to form a rake surface portion 206a and is connected to a floor panel 207. A curved surface portion 206b and a projecting portion 206c are integrally provided on the outer side of the rake surface portion 206a of the dashboard lower panel 206. The curved surface portion 206b is formed as an extension of a wheel apron and is connected to an outer panel 208. The projecting portion 206c is formed on the lower side of the curved surface portion 206b to bulge rearward and is connected to a side sill 209. The outer frame 201 of the front frame 203 extends rearwardly and is connected to the dashboard lower panel 206. A cutaway portion is formed in the inner frame 202 in front of the dashboard lower panel 206 at a predetermined distance therefrom. A lower gusset 210 and an upper gusset 211 extending in the longitudinal direction of the vehicle body are provided to cover the cutaway portion. The lower gusset 210 has, as clearly shown in Figure 16, a substantially channel-shaped cross-section with the height of the inner wall portion being gradually reduced rearward, and the outer wall portion being connected to the outer frame 201. Further, the rear end portion of the lower gusset 210 extends below the dashboard lower panel 206 and is bifurcated to form a pair of rear ends 210a and 210b. The rear end 210a is connected to a channel-shaped floor frame 212 connected to lower side of the floor panel 207 to extend in the longitudinal direction of the vehicle body. The other rear end 210b of the lower gusset 210 is connected to the side sill 209. Further, the lower gusset 210 is gradually bowed downward from a portion near the front side of the dashboard lower panel 206 toward the rear end portion 210a so that the rear end portion is smoothly merged into the floor frame 212, and is gradually bowed downward from a portion near the front side of the dashboard lower panel 206 toward the rear end portion 210b so that the rear end portion 210b forms a box-like cross section together with the projecting portion 206c of the dashboard lower panel 206. The peripheral edge portion of each of the bowed portions is connected to the dashboard lower panel 206 or the floor panel 207. The upper gusset 211 has a substantially L-shaped cross-section with the height of the inner wall portion being gradually increased rearward to conform to the shape of the inner wall portion of the lower gusset 210, and is connected to the lower gusset 210 at the inner wall portion, to the outer frame 201 at the outer wall portion and to the dashboard lower panel 206 at the rear end. The joint surface between the upper and lower gussets 210 and 211 is inclined rearwardly to be smoothly merged into the rearwardly inclined joint surface between the lower gusset 210 and the rake surface portion 206a of the dashboard lower panel 206. Figures 17 to 20 are cross-sectional views respectively taken along lines XVII-XVII, XVIII-XVIII, XIX-XIX, and XX-XX in Figure 15, and Figures 21a to 21d are cross-sectional views respectively taken along lines XXIa-XXIa, XXIb-XXIb, XXIc-XXIc and XXId-XXId in Figures 17 and 18. The members are spot-welded at places indicated by X's in Figures 17 to 21. As can be understood from the description above and from the drawings, in the front structure of this embodiment, the front frame 203 is connected to the rearward part of the vehicle body at the dashboard lower panel 206, the floor panel 207, the floor frame 212 and the side sill 209 by way of the lower and upper gussets 210 and 211, and the connecting points are distributed over a wide range of the frame structure. Accordingly, when an external force acts on the front frame 3, stress can be sufficiently dispersed, thereby substantially increasing rigidity of the vehicle body. At the same time, in the case of the structure of this embodiment, the part of the frame structure on the front side of the dashboard lower panel and the part of the frame structure on the rear side of the dashboard lower panel are continuous, and accordingly, load acting on the front frame can be transmitted to the floor frame and the side sill, whereby rigidity of the vehicle body can be further increased.

Claims: A front structure of a vehicle body comprising a front frame (3, 103) which extends in the longitudinal direction of the vehicle body and is formed of an outer frame (1, 101) and an inner frame (2, 102) connected together to form a closed cross section, a dashboard lower panel (6, 106) disposed near the rear end of the front frame and extending substantially vertically, a front floor (7, 107) extending rearwardly from the lower edge of the dashboard lower panel, a side sill (11, 109) disposed at the side edges of the front floor at a height lower than the front frame, a floor frame (7a, 112) disposed on the inner side of the side sill at a height lower than the front frame, a first frame member (12) connecting the rear end portion of the front frame to the side sill and a second frame member (13, 111) connecting the rear end portion of the front frame to the front end portion of the floor frame, characterized in that the inner frame (2, 102) of the front frame (3, 103) is channel-shaped in cross section and one of said outer frame (1, 101) and inner frame (2, 102) is bent so as to extend across the front frame toward the other one of the outer and inner frames at a portion near the rear side of a suspension tower (8), the bent portion (1a, 102b) being connected to said other one of the outer and inner frames. A front structure as defined in claim 1, characterized in that said inner frame (102) is bent so as to extend across the front frame toward the outer frame (101) at a portion near the front side of the dashboard lower panel (106), and a channel-shaped gusset (110) is provided to cover the bent portion, the gusset being connected to the inner frame (102) and the dashboard lower panel (106). A front structure as defined in claim 2, characterized in that the outer frame (101) of the front frame (103) extends below the outer portion of the dashboard lower panel (106) to form a closed cross section therewith and is connected to the side sill (109) with the cross section of the outer frame (101) gradually changing toward its rear end from a portion near the front surface of the dashboard lower panel, the outer frame thereby forming said first frame member. A front structure as defined in any of claims 2 and 3, characterized in that a channel-shaped joint frame (13, 111) extends forwardly from the front end of said floor frame (7a, 112), and the lower side of the gusset (110) is connected to the joint frame at the rear end, the lower side of the gusset gradually bowed downwardly toward the rear end thereby to smoothly merge into the joint frame. A front structure as defined in claim 1 or 4, characterized in that said first frame member is an outer rear frame (12) which is connected to the outer side of the outer frame (1) to extend rearwardly from a portion on the front side of the bent portion (1a) to cover the bent portion. A front structure as defined in claim 5, characterized in that the outer rear frame extends below the outer portion of the dashboard lower panel so as to form a closed cross section therewith and is connected to the side sill with the cross section of the outer rear frame gradually changing toward its rear end from a portion near the front surface of the dashboard lower panel. A front structure as defined in any of claims 1 to 6, characterized in that the lower portion of the dashboard lower panel comprises a rake surface portion (6a, 106a) bent obliquely rearwardly, curved surface portions (6b, 106b) formed on the outer edges, respectively, of the rake surface portion, and projecting portions (6c, 106c) respectively formed on the lower side of the curved surface portions so as to project rearwardly, each projecting portion being connected to the adjacent side sill (109). A front structure as defined in claim 7, characterized in that the outer rear frame (12) is gradually bowed downwardly from a portion near the front side of the dashboard lower panel toward the side sill so as to form a box-like cross section together with the respective one of the projecting portions (6c) of the dashboard lower panel. A front structure as defined in claim 6 or 8, characterized in that said second frame member is a joint frame (13) having a channel-shaped cross section and forming a closed cross section portion together with the rake surface portion of the dashboard lower panel, the front end portion of the joint frame being connected to the inner frame (2) of the front frame (3) and the rear end portion of the joint frame being connected to the front end of the floor frame (7a).

Inventors: MATSUURA, OSAMU, SAKIYAMA, NORITAKA
Applicants: MAZDA MOTOR CORPORATION
Application year: 1986
Main classification: B62D25
IPC codes: B62D25