Body for a motor vehicle

Abstract: The body of the invention substantially comprises a frame (1) capable of supporting several fixed and movable enclosing panels and a floor pan (2) defining the bottom of the interior; the floor pan is provided with suitable means of attachment for fixing it to the lower surface of the frame, and with suitable means for securing several mechanical parts and assemblies to the said floor pan to form a single unit, prior to the floor pan being fixed to the frame by the aforementioned means of attachment.

Description: The present invention relates to a motor vehicle body of the type comprising a frame suitable for supporting several fixed and movable enclosing panels, and a floor pan defining the bottom of the interior of the vehicle. The frame normally comrises two side members, two front supports fixed to the front end of the side members and forming therewith a pre-defined angle, a front cross member suitable for attaching the ends of the supports together, and a rear cross member suitable for attaching the rear ends of the side members together. In this type of body, the floor pan is normally fixed to the frame by non-dismountable means of attachment, for example by welding, or is fixed thereto using dismountable means of attachment normally comprising threaded parts. This type of body presents some disadvantages. First of all, complete body preparation requires numerous lengthy operations; in fact, after the floor pan has been attached to the frame in the aforesaid manner, it is necessary to fix basic mechanical parts and assemblies to the body, such as the servo-brake device, pedals, steering support cradle, steering box and seat support guides; these operations are difficult to execute, particularly because of the lack of access to the parts of the body to which these parts and assemblies must be attached. Furthermore, a body of this type is difficult to assemble in a fully automated manner using dedicated machines and devices. DE-A-2 923 874 discloses a motor vehicle body comprising a frame and a floor pan provided with attachment means for fixing the floor pan to the frame and with attachment means for fixing a plurality of mechanical parts and assemblies to said floor pan to form thereby a single unit prior to the floor pan being fixed the frame. The features known from DE-A-2 923 874 form the basis of the preamble of claim 1. An aim of the present invention is to provide a body for a motor vehicle of the aforementioned type, wherein the floor pan and the frame are connected in a simple manner by attachment means that has a high mechanical resistance and does not produce vibrations which are a source of noise. Such an aim is achieved by a body for a motor vehicle substantially comprising a frame capable of supporting several fixed and mobile enclosing panels and a floor pan defining the floor of the interior of the motor vehicle, said frame comprising two side members, two front supports fixed to the front end of the said side members and forming therewith a pre-defined angle, a front cross member suitable for attaching the ends of the said supports together and a rear cross member suitable for attaching the rear ends of the said side members together, said floor pan being provided with attachment means for fixing the floor pan to the lower surface of said frame and attachment means for fixing several mechanical parts and assemblies to said floor pan to form thereby a single unit, prior to the floor pan being fixed to said frame by said means of attachment, characterised in that said attachment means for fixing said floor pan to the said frame comprises a continuous seating obtained on three sides of said floor and suitable for resting against the lower surface of said side member and against the lower surface of the said rear cross member and a plurality of metal gussets each of which rests against the lower surface of said floor and is attached by means of threaded attachments to said side members and said rear cross member, a layer of elastic adhesive being placed between said continuous seating and said lower surfaces of the side members and of said rear cross member and between said floor pan and said gussets. For a better understanding of the body of the present invention there is now given, by way of an example, a detailed description thereof with reference to the attached drawings in which : figure 1 represents a perspective view of the basic elements of the body of the invention; figures 2, 3 and 4 represent plan, section and front views, respectively, of the floor pan of the body; figures 5 and 6 represent sections through the floor pan of figure 2, through planes V-V and VI-VI respectively; figure 7 represents a section of a part of the floor pan of figure 2 through plane VII-VII; figure 8 represents a section through a side member of the body frame and a part of the floor pan thereof; figure 9 represents a vertical section through the front part of the floor pan to which mechanical parts and assemblies of the motor vehicle are attached; figure 10 represents a section through a part of the floor pan suitable for illustrating the attachment of another mechanical assembly to the floor pan; figure 11 represents a transversal section of a cross member fixed to the floor pan; figure 12 represents a side view of the cross member of figure 11; figure 13 represents a detail, on a larger scale, of figure 12 suitable for illustrating the manner in which the cross member is attached to the side members of the frame; figures 14 to 16 represent various forms of realisation of the means for attaching mechanical parts and assemblies to the floor pan of the body. The body of the invention substantially comprises a frame, indicated as a whole by reference 1 (fig.1), which is capable of supporting several fixed and movable enclosing panels (not shown) and a floor pan 2. The frame, in turn, comprises two side members 3, two front supports 4 fixed to the front end of the side members and forming thereby a pre-defined angle, a front cross member 5 suitable for attaching the ends of supports 4 together and a rear cross member 6, suitable for attaching the rear ends of the said side members together. The floor pan 2, shown in figures 2, 3 and 4, substantially comprises a floor 7 and a fireproof wall 8 forming a pre-defined angle with the former and suitable for dividing the engine compartment from the interior of the vehicle. The floor 7 is shaped so as to produce a tunnel 9 and a cross member 10, visible in section in figures 5 and 6. Although the abovementioned floor pan can be constructed of sheet metal, it is preferably constructed by forming a semi-finished piece of plastic material; this comprises several layers of plastic material, at least two of which are external layers 11 (figures 8, 14, 15 and 16) having a higher density and mechanical resistance and at least one intermediate layer 12 with a lower density. The floor pan 2 is provided with means of attachment suitable for fixing it to the lower surface of the frame, and with means of attachment suitable for fixing several mechanical parts and assemblies to the floor pan to form thereby a single unit. This unit comprises, in addition to the floor pan, a servo-brake device 13 (figure 9), pedals 14, a steering support cradle 15, a steering box 16, two seat support guides 17 (figure 6) and an assembly 18 (figure 3) of which the handbrake and gear levers form a part. The means for attaching the floor pan to the frame comprises continuous seating 24 (fig.8) capable of resting against the lower surface 25 of side members 3 and on the lower surface 26 (figure 3) of rear cross member 6; such means of attachment further comprises several metal gussets 27 (figures 2 and 8) each of which is suitable for resting against the lower surface 28 of the floor 7 and for attachment, by threaded organs of attachment 29, to side members 3 and rear cross member 6. As is clearly seen in figure 2, some gussets 27 are provided, four of which are fixed to the side members and the others to the rear cross member 6 and front fireproof wall. In figure 8, the edges of the floor 7 are formed to produce a rim 30, turned towards the base, and each gusset 27 has a concavity 31 suitable for housing the said rim. Furthermore, between the continuous seating 24 and the lower surfaces 25 and 26 respectively of side members 3 and rear cross member 6 is placed a layer of elastic adhesive 32; a similar layer of adhesive 33 is interposed between the rim 30 and the concavity 31. Finally, conveniently, each gusset 27 has a lug 34 suitable for resting against the lower surface 25 of the floor 7, with the interposition of a further layer of elastic adhesive 35. The abovementioned means of attachment suitable for fixing the floor pan 2 to the frame 1 further comprises a layer of adhesive 40 (figure 1) placed between the edges of the fireproof wall 8 and the lower surfaces of the supporting elements 4 and front cross member 5. The floor pan 2, being constructed of a plastic material according to the aforementioned manner, may also comprise cross member 10 (fig.2), which is produced directly from the material of the floor 7, a separate cross member 41 (figures 11 and 12) constructed of sheet metal and having a substantially U-shaped section, as can be seen in figure 11; this cross member is fixed, in the manner indicated, to the side members 3 and is suitable for supporting seat guides 42 (figure 12). Each end of the said cross member is attached to a corresponding side member 3 by means of attachment shown in figure 13; it comprises substantially a seating 43 obtained on the outer edge of the floor 7 and suitable for resting against the lower surface 44 of a corresponding side member, at least one bolt 46 suitable for attaching the said edge to the side member and a lug 47 capable of being supported on the upper surface 48 of the said side member and of being fixed, by at least one other bolt 49, to the end of the cross member; between the seating 43 and the lower surface 44 of the side member is placed a layer of elastic adhesive 50. The aforementioned means of attachment suitable for fixing several mechanical parts and assemblies to floor pan 2 substantially comprises a metal plate 55 (figure 9), fixed to the internal surface 56 of fireproof wall 8 and provided with a cradle 15 suitable for supporting the steering column 58 and pedals 14. The said means of attachment further comprises several studs 60 fixed to the casing of the servo-brake 13, and several holes for these studs obtained in the fireproof wall and in the plate 55. The casing of the servo-brake is placed on the external surface 62 of the fireproof wall and the studs are secured by means of nuts 63, which therefore fix both the plate 55 and the servo-brake 13 to the fireproof wall. The other mechanical parts and assemblies which are fixed to the floor pan 7 before the latter is fixed to the frame 2 are the steering box 16 (figure 9) and assembly 18 for the gear and handbrake levers (figure 3). Among the parts to be fixed to the floor pan are included the seat guides 17 (figure 6). For the attachment of these latter mechanical parts and assemblies to the floor pan, means of attachment of the type shown in figures 14 to 16 can be used. Such means comprise a hole 66 (figure 15) obtained in the floor pan, a cavity 67 made on a surface of the said floor pan coaxially with hole 66, a cup-shaped metal washer 68 housed in the cavity 67 and fixed by a nut 69, and a bolt 70 which passes through a hole 71 obtained in a wall 72 of the mechanical part or assembly to be fixed to the floor pan. As can be seen, to realise such a fixture, the shank of the bolt 70 passes through the hole 71 and screws into threaded nut 69. As can be clearly seen in the figure, the nut 69 is provided with a sleeve having the function of a distance piece, suitable for making contact with wall 72 of the mechanical part or assembly to be fixed to the floor pan. Furthermore, conveniently, each of the means of attachment aforementioned can comprise a bush 73 (figure 16), inserted in hole 66 and provided with a flange 74 suitable for insertion between the floor pan and the wall 72 of the mechanical part or assembly to be fixed to the floor pan. Or, according to the more simplified form of figure 14, the metal washer 68 can be dispensed with. The means of attachment illustrated in figures 14 to 16 have different resistances, higher for that of the last of these figures; they can be used without distinction according to the mechanical resistance and stresses required of the attachment, but in each case are attached rigidly to the floor pan to enable the necessary tightening torque to be applied to ensure attachment of the various parts. Such means of attachment can be mounted either by concurrent pressing or by adhesion or by another known method. In the case of concurrent pressing, such means will be positioned in the press together with the fabric, and the resin which impregnates the fabric will ensure the adhesion thereof to the floor pan. In the case of adhesion between the metal cup-shaped washer 68 and the cavity 67, a layer of adhesive will be deposited. Mounting can be effected automatically by systems such as robots or mechanical arms, the tool holders of which will have a coil to heat the means of attachment to a suitable temperature. Alternatively, other heating systems with a high density of energy can be used such as laser or electron beam. The heat passing from the metal element to the adhesive will give it a rapid pre-polymerization and render superfluous the passage of the floor pan through suitable jigs or ovens. It is evident that the body described can be realised with very simple and quick operations and at low cost. In fact, a unit of elements is first realised comprising, in addition to the floor pan (2), mechanical parts and assemblies which have been described and which are fixed to the said floor pan, such as the servo-brake device 13, pedals 14, steering support cradle 15, steering box 16, seat support guides 17 and handbrake and gear lever assembly 18. This unit can be prepared with extreme ease and in a fully automated manner, due to the notable accessibility offered by the floor pan. It, in turn, is mounted on the frame 2 by bringing it into contact with the lower surface of the said structure and using the means of attachment which have been described above. The attachment realised between the floor pan and frame has a high mechanical resistance and does not produce substantial vibration which is a source of noise; in fact the attachment between the floor pan 2, side members 3 and front 5 and rear cross member 6 is effected by means of elastic elements, comprised of layers of elastic adhesive 32, 33 and 34 (figure 8) and layers of adhesive 40 (fig.1) which are interposed between the fireproof wall 8 and the front supports 4 and front cross member 5 of the frame. If such a floor pan is constructed with plastic material it can be produced with the forming technology normally used for these materials; in such a case, the weight of the body is also significantly reduced. It is evident that the described form of realisation of the present invention can be provided with modifications and variations, either in respect of the form, or the arrangement of the various parts, without exceeding the scope of the invention.

Claims: A body for a motor vehicle substantially comprising a frame (1) capable of supporting several fixed and mobile enclosing panels and a floor pan (2) defining the floor (7) of the interior of the motor vehicle, said frame comprising two side members (3), two front supports (4) fixed to the front end of the said side members and forming therewith a pre-defined angle, a front cross member (5) suitable for attaching the ends of the said supports together and a rear cross member (6) suitable for attaching the rear ends of the said side members together, said floor pan (2) being provided with attachment means (27,30) for fixing the floor pan to the lower surface of said frame and attachment means (55,60,69,70) for fixing several mechanical parts and assemblies to said floor pan (2) to form thereby a single unit, prior to the floor pan being fixed to said frame by said means of attachment, characterised in that said attachment means for fixing said floor pan (2) to the said frame (1) comprises a continuous seating (24) obtained on three sides of said floor (7) and suitable for resting against the lower surface (25) of said side members (3) and against the lower surface (26) of the said rear cross member (6) and a plurality of metal gussets (27) each of which rests against the lower surface (28) of said floor (7) and is attached by means of threaded attachments (46,49) to said side members (3) and said rear cross member (6), a layer of elastic adhesive (32,33,35) being placed between said continuous seating (24) and said lower surfaces (25,26) of the side members and of said rear cross member and between said floor pan (2) and said gussets (27). A body according to claim 1, characterised by the fact that the said unit comprises, in addition to the said floor pan, a servo-brake device (13), pedals (14), a steering support cradle (15), a steering box (16), two seat support guides (17), and a handbrake and gear lever assembly (18). A body according to claims 1 or 2, characterised by the fact that the said floor pan (2) has a first wall (7) suitable for creating the floor of the said interior and a second wall (8) suitable for creating a fireproof wall suitable for separating the said interior from the engine compartment, said fireproof wall forming a pre-defined angle with the said floor. A body according to one of the foregoing claims, characterised by the fact that the said means of attachment is capable of attaching pre-defined zones of the edge of the said floor (7) to the said side members (3) and said rear cross member (6) of the frame, and pre-defined zones of the edges of said fireproof wall (8) to the said supports (4) and said front cross member (5). A body according to one of the foregoing claims, characterised by the fact that the said floor pan is obtained by forming semi-finished plastic material, said floor pan comprising several layers of plastic material, with at least two external layers (11) of higher density and mechanical resistance and an intermediate layer (12) of a lower density. A body according to any of the preceding claims, characterised by the fact that the edges of the said floor (7) are shaped in such a way as to produce a rim (30) turned towards the base and each of the said gussets (27) comprises a concavity (31) suitable for housing the said rim. A body according to any of the preceding claims, characterised by the fact that each of said gussets (27) further has a lug (34) suitable for resting against the lower surface (28) of the said floor. A body according to claim 7, characterised by the fact that a layer of elastic adhesive (33, 35) is placed, between the said rim (30) and each of the said cavities (31) of the gussets, and between the said lower surface (28) of the said floor and the said lug (34). A body according to any of the preceding claims, characterised by the fact that it comprises 5 of said gussets (27), two of which are fixed to each side member (3) and one to the said rear cross member (6). A body according to one of the foregoing claims, characterised by the fact that the said means of attachment suitable for fixing the floor pan (2) to the frame (1) further comprises a layer of adhesive (40) placed between the edges of the said fireproof wall (8) and the lower surfaces of the said supports (4) and of the said front cross member (5). A body according to one of the foregoing claims, characterised by the fact that the said floor (7) is shaped in a manner to produce a longitudunal tunnel (9) and is provided with an opening for the passage of parts attached to the said gear lever and handbrake assembly (18). A body according to claim 11, characterised by the fact that the said floor (7) is further shaped in a manner to produce a cross member (10) provided with holes for the said means for attaching the said guides (17) to the floor pan. A body according to one of claims 1 to 11, characterised by the fact that it comprises a metal cross member (41) with a substantially U-shaped section in contact with the said floor (7) of the floor pan and suitable for supporting the seat guides (42), each end of the said metal cross member being attached to a corresponding side member (3) by parts of attachment. A body according to claim 13, characterised by the fact that the said parts of attachment comprise a seating (43) obtained on the peripheral edge of the said floor (7) and suitable for resting against the lower surface (44) of a corresponding side member, at least one bolt (46) suitable for securing the said edge to the said side member and a lug (47) suitable for resting against the upper surface (48) of the side member and for being secured, by at least one other bolt (49), to the said end of the cross member, a layer of adhesive (50) being interposed between the said seating and said lower surface of the side member . A body according to one of the foregoing claims, characterised by the fact that the said means of attachment suitable for fixing several mechanical parts and assemblies to the floor pan (2) comprises a metal plate (55) fixed on the internal surface (56) of the said fireproof wall and provided with the said cradle (15) suitable for supporting the steering column and the said pedals (14), several threaded studs (16) fixed to the casing of the said servo-brake (13) and several holes for the said studs obtained in the fireproof wall (8) and in the plate (55), the said servo-brake casing resting against the external surface (62) of the said fireproof wall and the said studs passing through the said holes and being secured by means of nuts (63). A body according to one of the foregoing claims, characterised by the fact that each of the said means of attachment of several mechanical parts and assemblies to the said floor pan comprises a hole (66) provided in the said floor pan, a cavity (67) obtained on a surface of the said floor pan coaxially to the said hole, a metal washer (68) in the form of a cup housed in the said cavity and secured by a nut (69) and a bolt (70) which passes through a hole provided in a wall (72) of the said mechanical part or assembly, said hole and said washer and which is screwed into the said nut. A body according to claim 16, characterised by the fact that the said nut (69) is provided with a sleeve with the function of a distance piece suitable for resting against the said wall (72) of the said mechanical part or assembly. A body according to claims 16 or 17, characterised by the fact that each of the said means of attachment comprises a bush (73) inserted in the said hole (66) of the said floor pan and provided with a flange (74) suitable for being interposed between the said floor pan (2) and the said wall (72) of the said mechanical part or assembly. A body according to claim 18, characterised by the fact that each of the said means of attachment is inserted by concurrent pressing or by adhesion. A body according to claim 19, characterised by the fact that each of the said means of attachment is inserted by automatic means and secured by an adhesive, polymerized by local thermal action with a high density of energy (induction, laser, Electron beam).

Inventors: BRUNO ALFONSO, TREVISAN LUCIANO, BRUNO, ALFONSO, TREVISAN, LUCIANO
Applicants: FIAT AUTO SPA, FIAT AUTO S.P.A.
Application year: 1990
Main classification: B62D25
IPC codes: B62D25, B62D65, B62D29