NL2025144B1

NL2025144B1 - Vehicle comprising a panel with adjustable flexibility

Info

Publication number: NL2025144B1
Application number: NL2025144A
Authority: NL
Inventors: Dijken Durandus
Original assignee: Atlas Technologies Holding Bv
Priority date: 2020-03-17
Filing date: 2020-03-17
Publication date: 2021-10-20

Abstract

Vehicle comprising a panel with adjustable flexibility. The invention relates to a vehicle (m) comprising a panel (204), characterized in that the panel has an adjustable stiffness, the stiffness a function of at least one of the 5 following conditions: . a speed of the vehicle with respect to an obstacle, . a speed of the vehicle with respect to a road surface, . a contact of the vehicle with an obstacle, . detection of an obstacle combined with a speed of the vehicle with respect to the 10 obstacle or road surface, the stiffness adjusted using a panel support structure (304) supporting the panel (202), the panel support structure having at least two configurations, a first configuration in which the stiffness of the panel is higher than when the support structure is in a second configuration, the panel support structure in the first configuration when the speed of the 15 vehicle below a predetermined speed or when the vehicle is not in contact with an obstacle and the panel support structure in the second configuration when the speed is above a predetermined speed or when contacting an obstacle. (Fig. 3)

Description

Vehicle comprising a panel with adjustable flexibility. Technical field of the invention.

[0001] The invention relates to a vehicle comprising a panel with variable flexibility.

Acknowledgement.

[0002] The project leading to this application has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No.

848620.

Background of the invention.

[0003] Vehicles, such as automobiles, have a multitude of panels, for example a bonnet and side or door panels. Such a panel has two contradictory demands: the panel should be stiff under vibration and torsion and when people lean or even sit on it, but should be pliable when a collision with a pedestrian occurs.

[0004] It is noted that ‘pedestrian’ in this context includes cyclists and children.

[0005] A good description of the problems occurring is given in publication https://pdfs.semanticscholar.org/5e61/84deae2617d7ded2b351843d5559fdb5dc40. pdf [-1-].

[0006] The problem may be even more severe when the panel has an outer surface that is made of a hard and relatively brittle material, such as glass. Such panels are used in, for example, solar cars, such as the Lightyear One, commercially available from Atlas Technologied B.V., Helmond, the Netherlands.

[0007] It is noted that an often occurring accident is the impact of the head on the bonnet.

[0008] US patent application publication US2002/0011365 to Honda addresses this problem. A bonnet is connected to the car using hinges at the side of the bonnet near the front window. The impact with a pedestrian is detected by a sensor, and when that occurs the hinges at side of the hood near the window are rapidly lifted by a spring, thereby lifting the bonnet itself. When now the head of the pedestrian impacts, the lifted part of the hood is pushed back again, absorbing energy, and the impact forces are lower than when the hood is not lifted.

[0009] Deployment time of such an active hood system, also known as a “pop-up bonnet” must be very fast, typically in the order of 10 ms from the moment that the sensor senses that the pedestrian touches the vehicle, see “A Shock Mitigation of Pedestrian-Vehicle Impact Using Active Hood Lift System: Deploying Time Investigation”, Tae-Hoon Lee et al., Shock and Vibration, vol. 2018, Article ID75895982016, https://doi.org/10.1155/2016/7589598, table 8 and accompanying text [-2-].

Itis worth mentioning that, if the impact is predicted by a sensor before the impact actually occurs, the deployment time can be longer, as the 10 ms is an estimate of the time from hitting the pedestrians’ legs to the impact of the head.

[0010] A disadvantage of this solution is that it does not help when the head impact occurs near the front of the hood, i.e. when impacting a child, as the impact point for children is close to the front of the bonnet, and the pop-up location is near the windscreen.

[0011] German patent application publication DE10102760A1 to Volkswagen describes a similar solution, with a similar disadvantage.

[0012] The invention intends to provide an improved or at least an alternative solution to this problem. Summary of the invention.

[0013] To that end a vehicle comprising a panel according to the invention is characterized in that the panel has an adjustable stiffness, the stiffness a function of at least one of the following conditions: ° a speed of the vehicle with respect to an obstacle, ° a speed of the vehicle with respect to a road surface, . a contact of the vehicle with an obstacle, . detection of an obstacle combined with a speed of the vehicle with respect to the obstacle or a road surface, the stiffness adjusted using a panel support structure having at least two configurations, a first configuration in which the stiffness of the panel is higher than in a second configuration, the panel support structure in the first configuration when the speed is below a predetermined speed or when not in contact with an obstacle and the panel support structure in the second configuration when the speed is above a predetermined speed or when contacting an obstacle.

[0014] When the vehicle is not moving, the panel support structure is in the first configuration the panel (for example the bonnet, also known as the hood) is stiff. Only when the vehicle has a speed of, for example, above 3 km/h, the panel support structure is brought in the second configuration resulting in a lower stiffness to reduce the effects of an impact with a pedestrian. The moment that the panel support structure must change from the first to the second configuration can be derived from:

- going from a parked situation to an activated situation of the vehicle, - the speed of the vehicle, - the speed of the vehicle with respect to a detected obstacle, - a contact of the vehicle with an obstacle.

[0015] Above a predetermined speed, for example above a speed of 50 km/h, the stiffness might rise again to avoid fluttering and/or vibration of the panel at high windspeed. It is noted that at such high speeds the impact point of the head impact then often is at the front window, instead of at the bonnet.

[0018] As known to the skilled artisan a hysteresis should be used when going from one configuration to the other. However, the change from one configuration to the other should take sufficiently fast, as can be derived from [-2-].

[0017] The panel support structure is preferably rigidly connected to the chassis or a subframe rigidly mounted thereon.

[0018] It is noted that to avoid vibrations a solid underpinning may be used, but also a damper comprising, for example, rubber, may be used.

[0019] In an embodiment the panel is a bonnet.

[0020] The bonnet of a car is the most obvious panel in this respect, although also pedestrian impact on, for example, door panels may occur.

[0021] In another embodiment which the panel support structure comprises a piston, an inflatable tube, or an inflatable bag, or a rotatable cam.

[0022] An implementation is to use a mechanical piston-in-cylinder, an rotatable cam, a tube that is inflated or a bag that is inflated. As clear to the person skilled in the art, each of these and other implementations can be used to achieve a combination of panel and panel support structure with adjustable stiffness.

[0023] In yet another embodiment the speed of the vehicle is estimated using a sensor from the group of radar, laser, camera, lidar, speedometer, or a GPS system.

[0024] Presumably the speedometer of the vehicle is used to determine the speed of the vehicle, but also the other types of sensors and read-outs can be used.

[0025] In another embodiment the speed and/or distance of the vehicle with respect to an obstacle is estimated using a sensor from the group of radar, laser, camera, or lidar.

[0028] By using one of the sensors to determine speed and/or distance to an obstacle, braking of the vehicle can be initiated as well as a change of the stiffness of the bonnet before an accident occurs.

[0027] In still another embodiment the contact of the vehicle with an obstacle is detected using one or more force sensors.

[0028] By incorporating one or more force sensors in the front bumper of the vehicle, contact of the vehicle with a pedestrian or any other obstacle can be detected.

[0029] In yet another embodiment the obstacle is a child, a pedestrian or a cyclist.

[0030] In still another embodiment the stiffness in the first configuration is at least twice as large as in the second configuration.

[0031] In still another embodiment the change from the first configuration and vice versa takes place within 0.5 second, preferably less than 0.1 second.

[0032] A change within 0.5 second may be enough at low speed and/or a detection of a dangerous situation before the pedestrian is hit (by radar, sonar, or the like), otherwise

0.1 second is the maximum response time, as discussed in [-2-]

[0033] In yet another embodiment the panel support structure has more than two configurations.

[0034] In yet another embodiment the panel support structure has a damping function that in at least one of the configuration s of the panel support structure dampens vibrations of the panel.

[0035] To avoid vibrations of the panel when driving at high speed, preferably a damper or a part comprising damping material is included in the panel support structure. As a result resonant vibrations caused by wind or road are suppressed.

[0036] In still another embodiment the vehicle comprises a front window, the panel is a bonnet and the vehicle further comprises a bonnet hinge system that operates to pop-up the side of the bonnet closest to the front window in response to an impending pedestrian impact.

[0037] Here the pop-up bonnet as described in e.g. US patent application publication US2002/0011365 to Honda is combined with the current invention.

[0038] In a preferred embodiment connection between the panel and the panel support structure comprise smart liquid and the change of rigidity is the result of a change of properties of the smart liquid.

[0039] By using a connection between the panel and the panel support structure that 5 comprises a smart fluid, such as a magnetorheological fluid or an electrorheological fluid, a connection can be made that changes its properties in milliseconds or less, due to a change of the fluid's viscosity.

[0040] It is noted that this embodiment can be used to have a continuously adjustable stiffness, as opposed to an adjustable stiffness with only two stiffness values.

Brief description of the drawings.

[0037] The invention is now elucidated using figures, in which identical reference signs indicate corresponding features. To that end: Figure 1 schematically shows an accident between a pedestrian and a vehicle, Figure 2 schematically shows a bonnet with several head impact areas, Figure 3 schematically shows a cross-section of the bonnet of figure 2 along line AA’, and Figure 4 schematically shows the use of a rheological fluid. Detailed description of the invention.

[0041] Figure 1 schematically shows an accident between a pedestrian and a vehicle.

[0042] A pedestrian 102 is hit by vehicle 100. If the pedestrian is an adult, the point of first impact is often at or near the knee. As a result the pedestrian will then hit the bonnet 104 with his/her head, often near the front window 106 of the vehicle. If the pedestrian is a child the impact is often more removed from the front window and near the feont of the vehicle.

[0043] Knee and head injuries are the most common serious injuries occurring during car/pedestrian accidents.

[0044] Figure 2 schematically shows a bonnet with several head impact areas.

[0045] A bonnet 104 shows several head impact areas 202, 204, 206 and 208. Head impact areas 202 and 204 are relatively close to the front window 106, while head impact areas 206 and 208 are more removed from the front window. It is likely that head impact areas 202 and 204 are associated with an impact between the vehicle and an adult, while head impact areas 206 and 208 are likely to be associated with an impact between the vehicle and a child. This is due to the ‘wrap-around distance’ (the distance measured from the ground surface up around the car contour to the head impact point) for adults ends close to the front window, while that for a child is closer to the front of the car.

[0046] Line AA’ is used to show where a cross-section of figure 3 is shown.

[0047] Figure 3 schematically shows a cross-section of the bonnet shown in figure 2 along line AA’.

[0048] A bonnet 202 is supported by a panel support frame 304 using a connection in the form of a piston in a cylinder. The piston can be extruded from the cylinder using a fluid, such as an oil. By pressurizing the fluid the piston is extruded from the cylinder and bonnet and piston touch each other, when the fluid is not pressurized the piston is retracted in the cylinder by, for example, a spring (not shown), and the piston and the bonnet do not touch each other. The pressurized situation corresponds with the first configuration of the panel support frame, as the bonnet is rigidly supported/connected to the panel support frame.

[0049] It is noted that the maximum travel of the piston/cylinder can be limited by a stop.

[0050] When the piston does not touch the bonnet, the bonnet is pliable.

[0051] It is noted that here a solution using a cylinder/piston is shown, but the skilled artisan will recognize that also other (mechanical) solutions, such as, but not limited to excentres, spindles etc. can be used. However, the transition from the first to the second configuration and vice versa should be fast enough.

[0052] It is further noted that the piston may comprise a damping material, for example a disk 308,

[0053] Figure 4 schematically shows the use of a rheological fluid.

[0054] A rheological fluid is a fluid (liquid) of which the viscosity is changed due to a magnetic field or an electric field.

[0055] In this figure the piston 402 is rigidly connected to the bonnet and moves in a first cylinder 404. The first cylinder is mounted on the chassis 408 or a subframe rigidly connected thereto. The first cylinder is filled with a rheological fluid 410. O-ring 406 hermetically seals the rheological fluid inside the first cylinder from the environment while enabling the piston to move in and out of the first cylinder. A second cylinder is connected to the first cylinder via a channel 412. The second cylinder 416 is only partly filled with the rheological fluid and partly filled with a (compressible) gas 418. Therefore the fluid can move from the first to the second cylinder. When the fluid is brought in a situation with a high viscosity, the fluid can move relatively easy from the first to the second cylinder. In other words: the piston can move easy in and out of the first cylinder. When applying a high electric field to the fluid via electrode 414 the viscosity becomes low, the fluid will not flow easy from the first to the second cylinder and the piston will not move easy in and out of the cylinder. This results in a higher stiffness of the bonnet. The change in viscosity occurs in a time in the order of a millisecond.

[0056] It is noted that pre-tensioning of the panel is possible using springs. The panel support structure can support the panel at one configuration, or at a multitude of configuration. Cited non-patent literature. [-1-] “Comparison of Steel and Aluminum Hood with same Design in View of Pedestrian Head Impact’, D. Schwarz et al. fka, Aachen, Germany, www.autosteel.org, hitps://pdfs. semanticscholar.org/Seg1/B4deze281/d7ded2b35184395559fdbsdc40. pdf [-2-] “A Shock Mitigation of Pedestrian-Vehicle Impact Using Active Hood Lift System: Deploying Time Investigation”, Tae-Hoon Lee et al., Shock and Vibration, vol. 2016, Article ID75895982016, https://doi.org/10.1155/2016/7589598, table 8 and accompanying text [-2-].

Claims

Conclusions.

A vehicle (100) comprising a panel (104, 204), characterized in that the panel has an adjustable stiffness, the stiffness being a function of at least one of the following conditions: a speed of the vehicle relative to an obstacle, . a speed of the vehicle relative to a road surface, . a vehicle contact with an obstacle, . detection of an obstacle combined with a speed of the vehicle relative to the obstacle or road surface, the stiffness adjusted using a panel support structure (304) supporting the panel, the panel support structure exhibiting at least two configurations, a first configuration wherein the stiffness of the the panel is higher than when the panel support structure is in a second configuration, the panel support structure in the first configuration when the speed of the vehicle is below a predetermined speed or when not in contact with an obstacle and the panel support structure is in the second configuration when the speed exceeds a predetermined speed or when the vehicle makes contact with an obstacle.

Vehicle according to claim 1, wherein the panel is a hood.

The vehicle of claim 1 or claim 2, wherein the panel support structure comprises a piston (306), an inflatable tube or an inflatable bag or a rotatable cam.

Vehicle according to one of the preceding claims, wherein the speed of the vehicle is estimated using a sensor from the group of radar, laser, camera, lidar, speedometer or a GPS system.

Vehicle according to any one of the preceding claims, wherein the speed and/or distance of the vehicle relative to an obstacle is estimated using a sensor from the group of radar, laser, camera or lidar.

A vehicle according to any one of the preceding claims, wherein the contact with an obstacle is detected using one or more force sensors.

A vehicle according to any one of the preceding claims, wherein the obstacle is a child, a pedestrian (102) or a cyclist.

A vehicle according to any one of the preceding claims, wherein the stiffness in the first configuration is at least twice as great as in the second configuration.

A vehicle according to any one of the preceding claims, wherein the panel support structure has more than two configurations.

A vehicle according to any one of the preceding claims, wherein the panel support structure has a damping function that dampens vibrations of the panel in at least one of the configurations of the panel support structure.

A vehicle according to any one of the preceding claims, wherein the vehicle comprises a windshield, the panel is a hood and the vehicle further comprises a hood hinge system that acts as a pop-up hinge on the side of the hood closest to the hood. windshield, fold up in response to an approaching impact with a pedestrian.

A vehicle according to any one of the preceding claims, wherein the coupling between the panel and the panel support structure comprises a smart fluid and the change in stiffness is the result of a change in properties of the smart fluid.

The vehicle of claim 12, wherein the smart fluid is a magnetorheological fluid or an electrorheological fluid and the change in stiffness is the result of a change in viscosity.