Vehicle steering and braking trigger logic for a pedestrian protection leg brace

Abstract

Method for controlling the operation of a pedestrian protection stiffener of a motor vehicle (10), comprising: Retracting the stiffener from an operating position when a measured steering angle of the motor vehicle (10) exceeds a limit angle.

Description

[0001] The present invention relates generally to a deployable pedestrian protection stiffener for a motor vehicle and, more particularly, to a deployment logic that takes into account the vehicle steering angle and / or deceleration.

[0002] Most current motor vehicles include a front bumper system designed to resist and / or cushion impact loads in the event of a collision. Typically, the bumper system includes a rigid bumper beam that extends transversely with respect to the vehicle and is sufficiently stiff to withstand a required impact energy. The bumper beam is attached to and supported by the vehicle frame, subframe, and / or body structure. In some cases, the bumper beam is attached to the forward ends of a pair of frame rails that extend longitudinally with respect to the vehicle and are spaced transversely from each other. Often, the forwardmost portion of the front frame immediately rearward of the bumper beam includes crumple zones designed to deform or collapse longitudinally to absorb impact energy in a predictable manner.The bumper system may also include numerous other bumper elements and / or decorative elements connected to the bumper beam and / or the front frame members. Bumper systems may also include one or more cover components exposed over and covering the bumper.

[0003] Several current national and multinational vehicle safety regulatory agencies have formulated pedestrian safety standards against which new vehicles are measured. At least one such vehicle safety test attempts to measure or estimate the degree of injury that occurs to the lower leg of a standing or walking pedestrian when struck by a relatively slow-moving vehicle. These tests generally indicate that a greater vertical clearance between the bumper and the road surface results in greater injury to the pedestrian's lower leg because the lower leg can slide under the bumper.

[0004] Simply reducing the bumper height to improve performance in such a test may not be a practical solution due to the resulting reduction in the vehicle's ground clearance. A relatively high ground clearance is especially important for vehicles that must operate off paved surfaces.

[0005] It is known to provide a so-called lower leg stiffener under the bumper, which is intended to prevent the bumper from sliding over the pedestrian's lower leg, thus reducing the likelihood and / or severity of injury upon impact with a pedestrian. If the stiffener is fixed, it can be damaged if it strikes an object in the vehicle's path.

[0006] DE 10 2005 008 029 A1, DE 103 24 514 A1, DE 199 21 480 A1, DE 10 2010 011 301 A1 and DE 10 2009 021 281 A1 disclose generic protective elements, front spoilers and bumpers.

[0007] The objective, technical problem to be solved can be seen as eliminating or at least mitigating the disadvantages of the prior art. This problem is solved according to the invention by the subject matter of the independent patent claims.

[0008] In a disclosed embodiment of a method for controlling the operation of a deployable pedestrian protection stiffener of a motor vehicle, the stiffener is retracted from a deployed position when a measured steering angle of the vehicle exceeds a limit angle.

[0009] In a further disclosed embodiment of the method, the stiffener is retracted from the deployed position when a vehicle brake is applied and a longitudinal acceleration of the vehicle simultaneously exceeds a limit acceleration.

[0010] In a further disclosed embodiment of the method, the stiffener is retracted from the deployed position when a measured speed of the vehicle falls below a lower limit.

[0011] In a further disclosed embodiment of the method, the stiffener is only retracted from the deployed position if the measured speed of the vehicle falls below a lower limit for longer than a predetermined period of time.

[0012] In another disclosed embodiment of the method, the stiffener has a retracted position behind a front side of a bumper beam and above a ground clearance plane of the vehicle, and in the deployed position, the stiffener is in front of the retracted position and below the ground clearance plane.

[0013] In another disclosed embodiment of the method, a method for controlling a deployable pedestrian protection stiffener of a motor vehicle includes deploying the stiffener when a vehicle speed exceeds a first value. The stiffener is subsequently retracted from the deployed position when one of the following conditions occurs: 1) the vehicle speed drops below a second value; 2) a vehicle steering angle exceeds a threshold angle; and 3) a vehicle brake is applied and a longitudinal acceleration of the vehicle simultaneously exceeds a threshold acceleration.

[0014] In a further disclosed embodiment of the method, the first value corresponds to the second value.

[0015] In a further disclosed embodiment of the method, the stiffener is also retracted when the vehicle speed increases above a third value which is greater than the first value.

[0016] In another disclosed embodiment, the pedestrian protection leg brace device comprises a pedestrian leg brace movably mounted on a motor vehicle, an actuator that moves the brace between a retracted position and a deployed position; and a controller that controls the actuator. The controller receives input from a steering system of the vehicle and commands the actuator to place the brace in the retracted position when the steering system input indicates that a steering angle exceeds a threshold angle.

[0017] In another disclosed embodiment of the apparatus, the controller further receives inputs from a braking system of the vehicle and an accelerometer and instructs the actuator to place the stiffener in the retracted position when the braking system input indicates that a vehicle brake has been applied and the accelerometer input simultaneously indicates that the vehicle is experiencing a longitudinal acceleration above a limit acceleration.

[0018] In another disclosed embodiment of the apparatus, the controller further receives an input from a vehicle speed sensor and instructs the actuator to place the stiffener in the retracted position when the speed sensor input indicates that a vehicle speed is below a lower limit.

[0019] In a further disclosed embodiment of the device, the controller instructs the actuator to set the stiffener in the retracted position only when the vehicle speed is below the lower limit for more than a predetermined period of time.

[0020] In another disclosed embodiment of the apparatus, the controller further receives an input from a vehicle speed sensor and instructs the actuator to place the stiffener in the deployed position when the speed sensor input indicates that a vehicle speed exceeds an upper limit.

[0021] In another disclosed embodiment of the device, the stiffener is located behind a front side of a bumper beam and above a ground clearance plane of the vehicle in the retracted position, and the stiffener is located in front of the retracted position and below the ground clearance plane in the deployed position. Fig. 1 is a schematic perspective view of a vehicle designed with a pedestrian protection leg stiffener; Fig. 2 is a schematic side view of the vehicle and the pedestrian protection leg stiffener of Fig. 1; Fig. 3 is a schematic view of a linear actuator for deploying a pedestrian protection leg stiffener; Fig. Figure 4 is a schematic side view of a pedestrian protection leg brace in a deployed position; Fig. 5 and Fig. 6 show, in flowchart form, an example of deployment logic for a leg stiffening system that takes into account the steering and braking of the vehicle in addition to the vehicle speed; and Fig. 7 is a system block diagram of a control system for controlling the stiffener position.

[0022] As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments merely illustrate by way of example the invention that may be embodied in various and alternative forms. The drawings are not necessarily to scale; some features may be exaggerated or reduced to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art how to variously employ the present invention.

[0023] Referring to Fig. 1 and Fig. 2, a motor vehicle 10 generally includes left and right front frame members 12, 14 oriented approximately longitudinally with respect to the vehicle. The front frame members 12, 14 may be parts of a traditional ladder-type frame, a front vehicle subframe, a unitary body / frame construction ("unit body"), or any known motor vehicle construction. The front frame members 12, 14 may include crumple zones.

[0024] A bumper assembly 16 extends generally transversely with respect to the vehicle and is attached to the left and right front frame members 12, 14 in a conventionally known manner. The bumper assembly 16 generally includes a rigid, high-strength bumper beam 18, typically formed from steel, an aluminum alloy, or a high-strength composite. As is well known in the art, the bumper beam 18 is a structural member designed to resist impact loads during a collision and transfer those loads to the front frame member 12, 14. If the front frame member 12, 14 includes crush zones, an impact of sufficiently high impulse will cause the front frame members to yield or deform to absorb the kinetic impact energy.

[0025] Referring to Fig. 2, the bumper assembly 16 may further include one or more other components, such as an upper apron 19, a lower apron 20 attached to a lower portion of the bumper beam 18, and / or a front spoiler 22 that may be integrally molded with the lower apron.

[0026] Left and right linear actuators 24, 26 are mounted adjacent to the inner surfaces of the front frame members 12, 14. As best shown in Fig. 2, the right linear actuator 26 generally comprises a fixed portion 26a attached to the front frame member 14 and a movable piston 26b. The right linear actuator 26 is attached to the right frame member 14 such that the piston 26b can be extended linearly along a deployment axis 30 oriented downwardly and forwardly at an angle α with respect to a line L parallel to the vehicle's longitudinal axis. The left linear actuator 24 similarly comprises a fixed portion attached to the left front frame member 12 and a movable piston that can be extended along a deployment axis at an angle α with respect to the vehicle's longitudinal axis.

[0027] A lower leg stiffener 28 is attached to the front or distal ends of the pistons 24b, 26b and can be moved between a retracted position and an extended or deployed position (shown in phantom lines in Fig. 1) by extending the linear actuators 24, 26. The stiffener 28 can be made of any suitable material, such as steel, aluminum, carbon fiber composites, or plastics. For example, computer-aided engineering (CAE) simulations were performed in which the stiffener was modeled as a 50 mm x 50 mm tube section with a wall thickness of 1.6 mm made of 6111 aluminum alloy.

[0028] How best in Fig. 2, in the retracted position, the stiffener 28 is located immediately below the front frame members 12, 14 and rearward of the front of the bumper beam 18. In the retracted position, the stiffener 28 is preferably disposed above a ground clearance plane 32. The ground clearance plane 32, as is well known in the art, is an imaginary plane typically created by drawing a straight line from a point contacting the front tire 34 to a lowermost portion of the bumper assembly 16 or any other component extending downwardly and / or forwardly from the bumper beam. The ground clearance plane 32 is thus the inclined plane below which no part of the vehicle structure extends.The ground clearance plane typically provides a minimum height of operating clearance and minimum ramp or departure angle clearance in front of the front tires for most vehicles sold in the standard market. Because the stiffener 28 is completely positioned above the ground clearance plane 32 when retracted, it is protected from impacting objects and does not reduce the vehicle's ground clearance.

[0029] Fig. Figure 4 shows the actuator 24 and the lower leg stiffener 28 in the deployed or extended position. The actuator 26 is not visible in this side view but is also in an extended state. In the deployed position, the linear actuators 24, 26 have been actuated to extend the pistons 24b, 26b downward and forward so that the stiffener 28 is located below the bumper beam 18 and below the ground clearance plane 32. When the stiffener 28 is in the deployed position, it prevents or inhibits a pedestrian's lower leg (not shown) from becoming trapped under the bumper assembly of a vehicle when the vehicle impacts the pedestrian.The value of the angle α at which the deployment axes 30 are oriented with respect to the horizontal and vertical position of the stiffener 28 between the ground surface and the bumper assembly 16 can be determined by the geometry of the respective vehicle type and the pedestrian protection objectives that the system is intended to achieve.

[0030] Fig. Figure 4 also shows the position of the stiffener in the retracted position, shown with the hidden line and indicated at 28'. The retracted stiffener 28' may be partially enclosed and / or concealed by the lower fascia 20 or other components of the bumper assembly 16. Alternatively, the retracted stiffener 28' may abut and / or fit within a recess in the lower structure of the bumper assembly (e.g., in the fascia 20) to provide an aerodynamic shape.

[0031] The linear actuators 24, 26 can be driven electrically, pneumatically or hydraulically. Fig. Figure 3 is a simplified schematic diagram of a possible embodiment with a helical rotary linear actuator in which a reversible electric motor 40 rotates a screw 42. A nut 44 engages the threads of the screw 42 and is fixed relative to a piston shaft 46. Consequently, rotation of the screw 42 by the motor 40 results in the extension or retraction of the nut 44 and the attached piston 46, depending on the direction of motor rotation.

[0032] Given the data collected on real-world pedestrian-vehicle collisions, pedestrian protection standards related to lower leg injuries generally only address vehicle operation at relatively low speeds. For example, some standards require a vehicle to meet lower leg injury targets only within a speed range of approximately 30 km / h (kilometers per hour) to approximately 80 km / h. Consequently, the stiffener can only be deployed when the vehicle is traveling within this speed range. Below 30 km / h, the stiffener remains in the retracted position, where it is protected from damage. If the vehicle driver sees an obstacle that must be negotiated and requires maximum ground clearance, they can decelerate the vehicle below 30 km / h, and the stiffener will retract.Above 80 km / h, the stiffening is also withdrawn to reduce air resistance and improve energy efficiency.

[0033] In addition, some vehicles may operate in off-road mode, in which certain vehicle systems (e.g., suspension and / or drivetrain) are configured to operate on unpaved, uneven surfaces, typically at lower speeds. Such an off-road mode may be manually selected by the vehicle operator (if such a switch is provided for the operator) and / or may be automatically triggered based on certain verified parameters. When operating in off-road mode, the vehicle is assumed to be traveling in an area unlikely to have pedestrians present, and it is assumed that the vehicle needs the greatest possible ground clearance to avoid impacting obstacles. In off-road mode, the deployment of stiffening is therefore suppressed regardless of vehicle speed.

[0034] Even if the vehicle is traveling at speeds within the "stiffener operating range" (and off-road mode has not been selected), there are certain circumstances where it may be beneficial to have the stiffener in the retracted position.

[0035] Fig. 5 and Fig. 6 shows an example of a stiffening application logic in the form of a flow chart, which also takes into account the vehicle's steering and braking conditions. At START in Fig. 5, the stiffener is in the retracted position and off-road mode (which suppresses stiffener deployment, as described above) is not selected. In step 100, the vehicle speed is read and compared in step 120 with a lower limit speed, in this example 30 km / h. If the speed is below this lower limit speed (step 110, NO), the logic returns to step 100 and the stiffener is held in the retracted position. If the speed is 30 km / h or above (step 110, YES), a timer is started in step 120 and the method continues to step 130 where the vehicle speed continues to be read (or monitored) and is compared with the lower limit speed in step 140.

[0036] If, when checking the vehicle speed in step 140, it is determined that the speed has fallen below 30 km / h (YES), the timer is stopped (step 150) and the process returns to step 100. If the speed remains above 30 km / h (step 140, NO), the process goes through steps 130, 140, 160 until the timer exceeds a predetermined time (10 seconds in this example), and the process continues to step 170, where the stiffener is inserted.

[0037] The vehicle speed continues to be read in step 180 and compared to an upper limit speed (in this example, 80 km / h) in step 190. If the upper limit is exceeded (step 190, YES), the combination of steps 190 to 240 results in the stiffener being held in the deployed position until the upper speed limit is exceeded for at least a predetermined period of time (in this example, 1 minute). If the time limit is exceeded (step 240, YES), the method reaches step 250, where the stiffener is retracted.

[0038] After the stiffener is retracted, the vehicle speed continues to be monitored (260) and compared with the upper limit (270). Steps 260 to 320, in combination, keep the stiffener retracted until the vehicle speed continuously falls below 80 km / h (or another selected upper limit speed) for over 1 minute (or another predetermined period of time), step 320, YES. The method then returns to step 100, and after completing steps 10 to 160, the stiffener is applied after another 10 seconds if the vehicle speed remains above 30 km / h for the specified period of time (step 160, YES).

[0039] The timer setting in the logic in Fig. 5 (steps 160, 240, and 320) and their respective speed thresholds prevent undesirable frequent periodic switching between the retracted and deployed positions of the stiffener, which may otherwise occur if the vehicle frequently exceeds the selected lower or upper speed limit. Note that by using a longer time threshold for retracting the stiffener than is necessary for its deployment (1 minute in step 240 versus 10 seconds in step 160 in the present example), the system tends to maintain the stiffener in its deployed position, thus providing protection for the pedestrian.

[0040] Returning again to Fig. 5, step 190, if (after the stiffening has been applied in step 170) the vehicle speed remains below 80 km / h (step 190, NO), the method continues with step 400 (see Fig. 6). When the speed drops below 30 km / h again (step 410 YES), a timer is started (step 420) and when the timer reaches 10 seconds (step 500, YES), the stiffener is withdrawn in step 450. This timer delay prevents, as described above with reference to Fig. Figure 5 explains unwanted periodic stiffening changes when the vehicle speed frequently falls above and below 30 km / h. During the running time of this timer delay, the remaining Fig. 6 but step 450 and pull back the stiffener in two cases.

[0041] In steps 430, 440, the steering angle is read (measured) and compared with a limit angle (60° in this example). If the steering angle equals or exceeds the limit angle, indicating a sharp turn, the stiffener is retracted to avoid the risk of damage.

[0042] In step 460, the vehicle's braking system status and longitudinal acceleration are read (monitored). If the vehicle brake has been applied AND the vehicle's longitudinal acceleration exceeds a threshold acceleration (0.2 g in this example), indicating an abrupt braking maneuver, the stiffener is retracted to prevent damage.

[0043] Overall, the Fig. 5 and Fig. The logic disclosed in Figure 6 is effective for deploying the stiffener when it is likely to reduce the risk and / or severity of pedestrian injuries, but retracts the stiffener when its effectiveness is unlikely and it may unnecessarily reduce ground clearance. Furthermore, this is achieved without unnecessary switching of the deployment mechanism.

[0044] Fig. Figure 7 shows in the form of a schematic block diagram an example of a device which determines the position of the stiffener according to the method described above with reference to Fig. 5 and Fig. 6. In this example, numerous vehicle performance and control inputs are communicated to a pedestrian safety controller 62, for example, via an electronic data bus, such as a Communication Area Network or CAN bus 65. The pedestrian protection controller 62 is preferably a microprocessor-based device that receives necessary inputs and applies appropriate programmed logic to maintain the position of a pedestrian leg brace by controlling actuators, such as the linear actuators 24, 26, which are connected with respect to Fig. 1-4 were discussed.

[0045] The pedestrian safety controller 62 receives, among other inputs: speed data from a vehicle speed sensor 60; steering angle data from the vehicle steering system 74; brake activation data from a vehicle braking system 70; vehicle acceleration data from an accelerometer 76 (e.g., an inertial navigation system (IMU)); and elapsed time information from a timer 78. Brake activation data from the vehicle braking system 70 may be a binary brake applied / disapplied signal from an electrical switch, or it may indicate a degree of braking.

[0046] An off-road mode selector switch 64 may be used to allow the driver to suppress the deployment of the stiffener as described above. Other vehicle systems, such as the stability control module 66, powertrain 68, braking system 70, and an adjustable suspension system 72, may also be adjusted according to the position of the on / off-road selector switch and / or additional inputs, as is well known in the art.

[0047] The information relating to Fig. 5-7 disclosed methods for controlling the stiffener and the system block diagram are not limited to the stiffener actuator Fig. 1-4, but can instead be applied to any applicable pedestrian protection leg stiffening device.

Claims

[1] A method for controlling the operation of a pedestrian protection stiffener of a motor vehicle (10), comprising: Retracting the stiffener from an operating position when a measured steering angle of the motor vehicle (10) exceeds a limit angle. [2] The method of claim 1, further comprising: Retraction of the stiffener from the deployed position when a vehicle brake is applied and a longitudinal acceleration of the motor vehicle (10) simultaneously exceeds a limit acceleration. [3] The method of claim 1, further comprising: Retracting the stiffener from the deployed position when a measured speed of the motor vehicle (10) falls below a lower limit. [4] A method according to claim 3, wherein the stiffener is only withdrawn if the measured speed of the motor vehicle (10) falls below the lower limit for more than a predetermined period of time. [5] The method of claim 1, further comprising: before the retraction step, the movement of the stiffener into the deployment position when a measured speed of the motor vehicle (10) increases above an upper limit. [6] The method of claim 1, wherein the stiffener is located in a retracted position behind a front side of a bumper beam (18) and above a ground clearance plane (32) of the motor vehicle (10), and wherein the stiffener is located in front of the retracted position and below the ground clearance plane (32) in the deployed position. [7] Method for controlling a pedestrian protection stiffener of a motor vehicle (10), comprising: stiffening begins when a vehicle speed exceeds a first value; Retraction of the stiffener when the vehicle speed falls below a second value; Retraction of the stiffener when a vehicle steering angle exceeds a limit angle; and Retraction of the stiffening when a vehicle brake is applied and a longitudinal acceleration of the motor vehicle (10) simultaneously exceeds a limit acceleration. [8] The method of claim 7, wherein the first value corresponds to the second value. [9] The method of claim 7, further comprising: Retraction of the stiffener when the vehicle speed increases above a third value that is greater than the first value. [10] Device comprising: a pedestrian leg brace movably mounted on a motor vehicle (10); an actuator (24, 26) which moves the stiffener between a retracted position and an deployed position; and a controller that receives an input from a steering system of the motor vehicle (10) and instructing the actuator (24, 26) to place the stiffener in the retracted position when the steering system input indicates that a steering angle exceeds a limit angle. [11] Device according to claim 10 wherein: the controller further receives inputs from a braking system (70) of the motor vehicle (10) and an accelerometer and instructs the actuator (24, 26) to set the stiffener to the retracted position when the braking system input indicates that a vehicle brake has been applied and the accelerometer input simultaneously indicates that the motor vehicle (10) is experiencing a longitudinal acceleration above a limit acceleration. [12] Device according to claim 10, wherein: the controller further receives an input from a vehicle speed sensor and instructing the actuator (24, 26) to place the stiffener in the retracted position when the speed sensor input indicates that a vehicle speed is below a lower limit. [13] Apparatus according to claim 12, wherein the controller instructs the actuator (24, 26) to place the stiffener in the retracted position only when the vehicle speed is below the lower limit for more than a predetermined period of time. [14] Device according to claim 10, wherein: the controller further receives an input from a vehicle speed sensor and instructing the actuator (24, 26) to place the stiffener into the deployed position when the speed sensor input indicates that a vehicle speed exceeds an upper limit. [15] The device of claim 10, wherein the stiffener in the retracted position is located behind a front side of a bumper beam (18) and above a ground clearance plane (32) of the motor vehicle (10), and wherein the stiffener in the deployed position is located in front of the retracted position and below the ground clearance plane (32).

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