Passive structural design that improves impact signal during side impact

A vehicle includes a floor structure and one or more tubular rocker structures. Each rocker structure includes an outer cladding and/or an inner structure extending across an interior space of the rocker structure. At least one acceleration sensor is connected to a central portion of the floor structure to detect acceleration resulting from a crash event. The vehicle may also include pressure sensors that detect changes in pressure in the door cavities that result from side impacts. The cladding and/or inner structure of the rockers reduce the time required to detect acceleration due to a side impact on the rocker structures.

FIELD OF THE INVENTION

The present invention generally relates to motor vehicles, and more particularly, to a vehicle structural design and crash sensing system that distinguishes between vehicle crashes and non-crash events and provides for quicker airbag deployment if a vehicle crash event occurs.

BACKGROUND OF THE INVENTION

Motor vehicles may be tested to determine the effects of a side impact on a vehicle door. Such tests are known as a “pole test.” These tests seek to simulate the effects of a crash even involving a side impact on a vehicle door. During the impact of a vehicle subjected to a lateral speed of 20 mph, contact between the occupant and the interior side structure of the vehicle can occur during the first 20 ms.

Vehicles may be equipped with pressure sensors in the doors to detect an early impact and deploy airbags or other restraint systems. The sensors contain elements whose deformations are measured and converted to electrical signals representing pressure values in the door cavities. Pressure sensors are generally effective in measuring deformations in a door cavity indicative of a vehicle crash with a Moving Deformable Barrier (MDB) or pole. However, there are events where deformation of the door cavity can occur, but deployment of side restraints (e.g. side airbags) are not required or desired. For example, deployment of side airbags would typically not be required as a result of slamming a vehicle door, a very low speed parking lot impact, or other such non crash events. To protect against inadvertent deployments, an acceleration sensor may be placed near the vehicle centerline within a Restraints Control Module (RCM) to determine the plausibility of a crash event. The restraint system may be configured to deploy the side airbags or other restraints only if the pressure sensors detect deformation in a door cavity and an accelerometer also detects acceleration exceeding a predefined threshold.

SUMMARY OF THE INVENTION

One aspect of the present invention is a vehicle structure including a primary structure having a unitized floor structure and an upper vehicle structure above the unitized floor structure. The primary structure defines a passenger space between the unitized floor structure and the upper vehicle structure and includes openings on opposite sides to permit user ingress and egress to the passenger space. The vehicle may include doors that are movably mounted to the primary structure to selectively close off the first and second openings. Rocker structures extend along lower edges of the openings. The rocker structures have a closed cross section and define internal cavities. The rocker structures include upper portions above the internal cavities, lower portions below the internal cavities, an outer portion extending between the upper and lower portions on an outer side of the internal cavities, and inner portions extending between the upper and lower portions on inner sides of the internal cavities. The unitized floor structure may include a center tunnel that extends in a fore-aft direction, and horizontal side portions that extend horizontally between the inner portions of the rockers and the center tunnel. An acceleration sensor is connected to the center tunnel of the floor structure to detect lateral acceleration of the floor structure at the center tunnel. Each rocker includes a substantially rigid central structure disposed in the internal cavity. The rigid central structure extends from the outer portion to the inner portion such that a side impact on the outer portion of the rocker generates a side impact signal that is transmitted through the rigid central structure and at least one of the side portions of the floor structure to the acceleration sensor. The acceleration sensor is able to detect a lateral acceleration due to the side impact signal that has been transmitted through the substantially rigid central structure of the rocker.

Another aspect of the present invention is a vehicle structure including a floor structure having a generally horizontal central portion and opposite side portions. A tubular rocker structure extends in a fore-aft direction along the opposite side portions. The rocker structures further include outer side walls having outwardly facing central portions, upwardly facing upper portions, and downwardly facing lower portions. The rocker structures further include inner side walls, and the opposite side portions of the floor structure are connected to the inner side walls of the rocker structures. A substantially rigid cladding comprising polymer or other suitable materials is disposed on at least a portion of the outer side walls of the rocker structures. The polymer cladding extends over the central portions and at least one of the upper and lower portions such that an impact force on the polymer cladding is transmitted from the polymer cladding to the inner side wall and to the floor structure. The vehicle structure further includes a rigid structural front cross member extending between the rocker structures in front of the central portion of the floor structure. A rigid structural rear cross member extends between the rocker structures. The rear cross member is positioned rearwardly of the central portion of the floor structure. An acceleration sensor is connected to the central portion of the floor structure that is spaced apart from the front and rear cross members.

Another aspect of the present invention is a vehicle including a floor structure with tubular rockers extending fore-aft along opposite sides thereof. The tubular rockers have rigid internal braces extending horizontally inside the rockers between inner and outer side walls of the rockers to directly transmit side impact forces on the rockers into the floor structure. The vehicle further includes rigid, horizontally spaced apart front and rear cross members. An acceleration sensor is mounted on a center portion of the floor structure that is approximately midway between the front and rear cross members.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference toFIGS. 1 and 2, a motor vehicle1includes a vehicle structure2having an upper portion4and a floor structure6. The vehicle structure2includes side openings8and10on opposite sides thereof with rocker structures18extending below the side openings8and10. As discussed in more detail below, the rocker structures18have increased stifthess/strength such that side impact forces on rocker structures18are transmitted into floor structure6such that a centrally located Restraints Control Module62can detect transverse acceleration more quickly to thereby permit quicker deployment of passenger restraints such as side airbags.

The side openings8and10are selectively closed off by a pair of front doors12and a pair of rear doors14to provide user ingress and egress to the passenger space16. In the illustrated example, the vehicle1includes front and rear doors12and14, respectively. However, the present invention is not limited to a four door vehicle, and other vehicle configurations (e.g., two door vehicles) are contemplated by the present invention. Furthermore, although the vehicle1ofFIGS. 1 and 2comprises an automobile, a vehicle structure according to the present invention may also be utilized in connection with a wide range of vehicles such as pickup trucks, vans, SUVs, sedans, hatchbacks, or virtually any vehicle configuration having rocker panels.

Referring toFIG. 2, floor structure6includes a generally horizontal primary or central portion20and a center tunnel22that extends in a fore-aft direction to accommodate drive train components24. Rocker structures18extend fore-aft along opposite edge portions26of floor structure6. A rigid front cross member28extends between the rockers18adjacent a front portion32of the floor structure6, and a rigid rear cross member30extends between rockers30adjacent a rear portion34of floor structure6. The vehicle structure2may include a front subframe44and rear subframe46to support an engine48and provide for structural support of the vehicle suspension. The vehicle structure2generally comprises a unibody structure, and the vehicle structure2therefore does not include a separate ladder-type frame or other such structure.

Vehicle1also includes front wheels36disposed in front wheel wells38and rear wheels40disposed in rear wheel wells42. The rockers18include opposite end portions50and52disposed adjacent front and rear wheel wells38and42, respectively. As discussed in more detail below, the rockers18have a generally tubular construction forming an elongated internal space104A, and extend linearly in a fore-aft direction between the wheel wells38and42. In general, the front cross member28extends between the front portions50of the rockers18, and the rear cross member30extends between the rear portions52of the rockers18. Thus, the front and rear cross members28and30together with the rockers18form a generally rectangular or quadrilateral structure extending around the primary or central portion20of the floor structure6. In general, the center tunnel22extends fore-aft along a vehicle centerline54between the front and rear cross members28and30, respectively.

As discussed in more detail below, the rockers18have a generally hollow tubular construction, and may include an internal bracing structure56and/or an external cladding58. In the event of an impact with a pole60or other object the internal bracing structure56(FIG. 3) and/or external cladding58(FIG. 4) that directly transmit force “F” from a side impact through the rocker18and through the primary or central portion20of floor structure6to a central portion64of center tunnel22. A Restraints Control Module (RCM)62is mounted on the central portion64of center tunnel22. The RCM62includes one or more sensors that detect acceleration due to a side impact of the vehicle1with a pole60or other object. The front and rear doors12and14include internal cavities13and15, respectively. Pressure sensors66A and66B are configured to measure changes in pressure in the cavities13and15. The system may, optionally, include additional acceleration sensors (test shown) that are mounted in doors12and14and/or other vehicle structures such as the door beam, B-pillar, or other substantial structural member near the outer portion of the vehicle structure. The RCM (or other controller) may be configured to utilize the inputs from the additional sensors to evaluate the plausibility of an impact event to thereby determine if the passenger restraints are to be deployed.

The RCM62includes a controller that is configured to access the plausibility of a crash event utilizing pressure information/data from the pressure sensors66and acceleration information/data from the accelerometers of the RCM. In the event of a crash event, the RCM62actuates (“fires”) one or more side airbags and/or other restraints. As discussed in more detail below, the internal bracing structure56and/or external cladding58of rockers18causes an acceleration signal to propagate through the rockers18and central portion20of floor structure16to the accelerometers of RCM62in a very short period of time. This enables the RCM to access the plausibility of a crash event and actuate or fire the restraints in a very short amount of time (e.g. about 7 ms). It will be appreciated that this is significantly quicker than similar vehicle structures that do not include internal bracing structure56and/or external cladding58. For example, as discussed in more detail below in connection withFIG. 10, vehicle structures that do not include the internal bracing structure56and/or external cladding58may have a firing time of 10 ms or more. Significantly, this reduction in time is achieved without positioning the RCM on or adjacent a rigid cross member.

With further reference toFIG. 3, a rocker18according to one aspect of the present invention includes an inner member68A and an outer member70A. The inner and outer members68A and70A are generally C-shaped in cross section, and include upwardly extending flanges72A and74A that are welded together along a seam76. The inner and outer members68A and70A also include downwardly extending flanges78A and80A that are welded together along a seam82. The inner and outer members68A and70A, respectively, may be fabricated from sheet metal (e.g. steel or aluminum) or other suitable material. Inner member68A includes a central portion84A that is welded or otherwise secured to the floor structure6. The inner member68A further includes an upper portion86A and a lower portion88A. Outer member70A includes a central portion94A, upper portion96A, and lower portion98A. It will be understood that the rocker members68A and70A may have different shapes and sizes as required for a particular application. For example, the central portions94A and/or84A may be substantially flat as shown inFIG. 3, or they may have a convex or concave curved contour as required for a particular application. The floor structure6comprises sheet metal or other suitable material. Floor structure6is generally horizontal, and defines a horizontal floor plane92A.

Internal bracing structure56A extends between the central portions84A and94A of inner and outer members68A and70A, respectively. Bracing structure56A may comprise high density foam as shown inFIG. 3, or it may comprise metal or other relatively rigid material. If an external force F is applied to the central portion94A of outer rocker member70A, the force is transmitted through internal bracing structure56A and into central portion20of floor structure6. The impact force is transmitted along a direct path108A to the accelerometers63in RCM62that is substantially linear, thereby significantly reducing the amount of time required for the signal to travel to RCM62. The transmission of an impact force in a manner that causes acceleration at the RCM62may be referred to herein as a signal.

As discussed below, the internal bracing structures56A-56F of the embodiments ofFIGS. 1-9, respectively, may comprise virtually any material or combinations of materials that have sufficient strength and stiffness to transmit sufficient side impact forces on the rocker structures18-18F into the floor structure6to permit detection of acceleration by RCM62. For example, the bracing structures56A-56F may comprise rigid, closed cell foam, polymer honeycomb structures (not shown) polymer or foam structures similar to egg crates, metal (e.g. steel) plates or flanges or other material/structural configurations having sufficient rigidity/stiffness. It will be understood that the internal bracing structures56A-56F may not be required in every instance, particularly if a relatively rigid cladding (e.g. cladding58B,FIG. 4, cladding58C,FIG. 6) is utilized to cover at least a portion of the rocker structure18-18F. A cladding may optionally be utilized with any of the rocker structures18-18F to provide increased structural rigidity and thereby reduce the time required for an acceleration detected by RCM62to exceed a predefined acceleration threshold134described in more detail below in connection withFIG. 10. In general, the bracing structures56A-56F ofFIGS. 1-9and/or the cladding are configured to significantly reduce the time required to detect a predefined threshold level of acceleration at RCM62. This reduction in detection time may be on the order of 10%, 20%, 30%, or more relative to rocker structures that do not include an internal bracing structure or a rigid cladding.

InFIG. 3, the RCM62is illustrated as being mounted on a relatively flat portion of floor structure6. However, it will be understood that the RCM62may also be mounted to a center tunnel22as shown inFIG. 2. InFIG. 3, the foam of internal bracing structure56A does not completely fill the internal space104A defined by the tubular rocker structure18, thereby forming an upper space100A above the bracing structure56A, and a lower space102A below the bracing structure. However, the internal bracing structure56A may, alternatively, also substantially fill the internal space104of rocker structure18such that upper and lower spaces100A and102A (FIG. 3) do not exist. Also, referring toFIG. 2, the internal bracing structure56A may have a length (see also length L1,FIG. 5) that is substantially less than the overall length of the rocker structures18, such that the internal bracing structure56A only extends across a central portion106of rocker structures18. Alternatively, the internal bracing structure56A may extend along substantially the entire length of the rocker structures18.

With further reference toFIG. 4, a rocker structure18B according to another aspect of the present invention includes inner and outer members68B and70B, respectively that are similar to the rocker members68A and70B ofFIG. 3. The members68B and70B are welded together at joints68B and82B along flanges74B,72B, and80B,78B, respectively. In the illustrated example, the outer member70B has a central portion94B that is not vertical, but rather angles or slopes inwardly somewhat along the top of the outer member70B. However, it will be understood that the inner and outer members68B and70B, respectively, the central portion94B may be substantially vertical or it may be sloped outwardly rather than inwardly. The inner member68B includes a central portion84B that is welded to the floor structure6at welds90B.

A cladding58B extends over and around outer rocker member70B. The exterior cladding58B may include an outer shell110B, and internal foam112B. The shell110B may comprise a suitable polymer material, a sheet of metal (e.g. steel), or other suitable material, and the foam112B may comprise a substantially rigid foam or other material having sufficient stiffness/rigidity to transmit force. The cladding58B is relatively rigid, such that an impact force F at horizontal plane92B of floor structure6is transmitted through the cladding58B along a load path108B around the upper portions86B and88B of inner rocker member68B and through the central portion20of floor structure6. Rocker structure18B may optionally include an inner bracing structure56B that is similar to bracing structure56A (FIG. 3). The internal bracing structure56B may comprise high density foam, metal, or other suitable material as may be required for a particular application. The external cladding structure58B (and internal bracing structure56B, if present) significantly increases the rigidity of the rocker structure18B, and allows a signal due to an external impact force F to travel through the central portion20of floor structure6to the RCM62in significantly less time than conventional rocker structures that do not include the cladding58B and/or internal bracing structure56B.

With further reference toFIGS. 5 and 6, a tubular rocker structure18C according to another aspect of the present invention includes inner and outer members68C and70C that may be formed from sheet metal or other suitable material and welded together in substantially the same manner as described above in connection with the rocker structures18A and18B (FIGS. 3 and 4). An external cladding58C includes an outer shell110C and inner foam112C. The outer shell110C may have a C or L shape, and the inner foam112C may be adhesively bonded directly to the outer rocker member70C. The length “L1” (FIG. 5) of the foam112may be significantly less than the length “L2” of the outer shell110C. The length L2of the outer shell110C may be substantially equal to the overall length of the rocker structure18C (i.e. rockers18ofFIGS. 1 and 2), and the rocker structure18C may extend across substantially the entire length of the vehicle between the front and rear wheel wells38and40. The foam112C may be adhesively bonded to an inner surface114C of outer shell110. The inner foam112C may be positioned outboard of central portion20of floor structure6(FIG. 2) such that the inner foam112C is generally aligned with RCM62. An impact force F is transmitted through the shell110C and foam112C into outer rocker member70C, and the load travels around lower portions88C and98C of inner and outer rocker members70C and68C. A signal (force) due to an impact force F is transmitted through the central portion20of floor structure6to the RCM62. Although a portion of the signal may be transmitted through the front and rear cross members28and30, a sufficiently large signal travels through central portion20of floor structure6to permit sensors63of RCM to detect a crash event. The central portion20of floor structure6may comprise sheet metal or other relatively thin material to provide sufficient passenger space16(FIG. 1) without requiring increased vehicle height.

An inner bracing structure56C may optionally be disposed within internal space104C of rocker structure18C. The internal bracing structure56C may comprise high density foam, metal, or other suitable material. The inner foam112may extend substantially the entire length of outer shell110C, such that the inner foam112C has a length that is substantially equal to the length L2(FIG. 5).

With further reference toFIG. 7, a rocker structure18D according to another aspect of the present invention includes inner and outer members68D and70D, respectively, that may be welded together to form an internal space104D. An internal structure56D extends between the inner and outer rocker members68D and70D along a plane92D of floor structure6. The internal bracing structure56D may comprise a metal structure having a generally planar central portion116D with flanges118D and120D that are secured to the inner and outer rocker members68D and70D by welding or other suitable arrangement. The bracket or internal structure56D provides for direct transmission of a signal caused by an external force F along a relatively straight path108D to the RCM62. It will be understood that the structure56D may comprise a plurality of individual bracing members, or it may comprise a single member that extends along a portion of the length of the rocker structure18D (e.g. internal structure56D could have a length similar to the length L1ofFIG. 5). Alternately, the internal bracing structure56D could extend along substantially the entire length of the rocker structure18D.

With further reference toFIG. 8, a rocker structure18E according to another aspect of the present invention may include a single rocker member70E that is substantially C shaped. An internal bracing structure56E provides for a direct load path108E in the event an external force F is applied to the rocker structure18E. The outer rocker member70E may optionally include an inner portion122E that extends from lower end portion124E of outer member70E to an outer edge portion126E of floor structure6.

With further reference toFIG. 9, a rocker structure18F according to another aspect of the present invention includes inner and outer members68F and70F, respectively that may be welded together as described above in connection withFIGS. 3-8. An optional inner bracing structure56F extends along lower portions88F and98F of inner and outer rocker member68F and70F, respectively. The outer rocker member70F is generally contoured such that the lower portion128F protrudes outwardly somewhat, such that a force F due to an external impact is transmitted directly along a relatively linear load path108F to the RCM62and accelerometers63. However, the rocker members68F and70F may have virtually any shape as required. The internal bracing structure56F may comprise metal or other suitable material, and may be welded to the inner and outer rocker members68F and70F, respectively.

The rocker structures18-18F ofFIGS. 1-9preferably extend linearly along opposite edge portions26of floor structure6(FIG. 1). However, the rocker structures18-18F may have a non-linear curved configuration according to other aspects of the present invention. Also, with the exception of rocker18E, rockers18-18F ofFIGS. 1-9preferably have a two piece “clam shell” type construction wherein the inner and outer sheet metal components are welded together. However, the rockers18-18F may comprise one piece members and may have virtually any suitable construction and may have virtually any contour and cross sectional shape. An RCM62of a vehicle having a rocker structure as described in more detail above in connection withFIGS. 1-9generates a signal to deploy the side impact air bags and/or other restraints in significantly less time than a similar vehicle having a conventional rocker structure.

FIG. 10is a graph showing test results (i.e. the acceleration measured by an RCM62) of a baseline vehicle (line130) having a conventional rocker structure with no internal rocker structure or cladding during a “pole test.”FIG. 10also shows the acceleration measured by an RCM (line132) during a pole test of a vehicle including a rocker structure according to the present invention. A predefined acceleration threshold134is chosen as a criteria to determine if a sufficiently large acceleration has been measured by RCM62to detect a side impact event requiring deployment of side air bags and/or other passenger restraints. In the illustrated example, the acceleration threshold134required at accelerometers63to fire or deploy the restraints is in the range of about 2.0 g to about 6.0 g. The acceleration threshold may be selected according to the requirements of a particular vehicle type or other relevant criteria. Referring again toFIG. 10, time τ0(0.0 seconds) corresponds to the moment of impact of vehicle1on a pole60(FIGS. 1 and 2) during a “pole test.” The accelerometers of the RCM of the baseline vehicle reach the threshold134at a time τ2of about 10.4 ms. However, as shown by the line132, the accelerometers63of an RCM62of a vehicle having a rocker structure according to the present application exceeds the acceleration threshold134at a time τ2of about 7.2 ms. In general, the times τ, and τ2are the times at which RCM62determines that a side impact event has occurred and generates a signal to deploy the side airbags and/or other passenger restraints. In the example ofFIG. 10, the reduction in time (ΔT) to deploy the restraints is about 3.2 ms (i.e. on the order of a 30% reduction in the time delay). However, the actual reduction in deployment time will depend on the specific vehicle structure and rocker structure utilized in a particular application of the present invention.

The RCM62may be configured to deploy/fire the restraints only if a door pressure sensor66A (FIG. 1) detects a pressure increase and the accelerometers63of RCM also detect an acceleration exceeding the acceleration threshold134.

As shown inFIG. 10, the rocker structure of the present invention significantly reduces the time required for the accelerometer63of RCM62to exceed the acceleration threshold. The rocker structure of the present invention thereby permits significantly faster deployment of the side impact airbags or other restraint systems, while still providing for accurate assessment of the plausibility of a crash event to prevent unwanted/inadvertent deployment of the side airbags. Significantly, rocker structures according to the present invention permit the force F (FIG. 2) to be transmitted directly through the primary or central portion20of the floor structure6to the RCM62even if an impact force F is applied to the rocker structure18at a location that is midway between the front and rear cross members28and30, respectively. Furthermore, the internal bracing56and/or external cladding58may be utilized in connection with rocker structures18that are substantially similar to known rocker structures such that extensive modification of the rocker structures and other related structures is not required.