WHEEL SYSTEM WITH BRAKE AND CORRESPONDING BRAKING ENHANCEMENT

Abstract

An automotive vehicle wheel and brake system includes a wheel axle, an angularly split wheel drum, the wheel drum including at least two separate wheel segments that are each radially movable, and a deforming actuator system including a deforming actuator to displace at least one of the wheel segments relative to at least another segment in such a way that an outer circumference of the wheel is temporarily deformed. The deforming actuator system also includes an electronic system that, during at least one predefined braking process, triggers the deforming actuator system so as to impose a temporary shape deformation of the split wheel drum.

Claims

1-10. (canceled)

11. An automotive vehicle wheel and brake system, comprising a wheel axle; an angularly split wheel drum to rotate around the wheel axle and to support the vehicle weight by contacting the ground directly or through a tire, the wheel drum comprising at least two separate wheel segments that are each radially movable so as to vary a maximum outer radius measured from the wheel axle; a deforming actuator system comprising a deforming actuator configured to displace at least one of the wheel segments relative to at least another of the wheel segments such that an outer circumference of a wheel is temporarily deformed from a circular shape to a different shape, wherein the deforming actuator system comprises an electronic system that is configured to, during at least one predefined braking process, trigger the deforming actuator system so as to impose a temporary shape deformation of the split wheel drum.

12. The automotive vehicle wheel and brake system according to claim ii, further comprising: a main braking system to stop rotational motion of the drum around the wheel axle; a wheel speed estimator to estimate a rotational speed of the split drum; and a wheel position sensor to estimate an angular position of the split drum, wherein the electronic system is configured to trigger a braking process in view of stopping the vehicle, and wherein the electronic system is configured to trigger the deforming actuator system to induce the temporary shape deformation of the split drum during the braking process when the angular speed of the wheel is less than a first speed threshold, and when the position of the split drum is within a predefined group of angular positions.

13. The automotive vehicle wheel and brake system according to claim 11, wherein, during the predefined braking process, the wheel segments are displaced by the deforming actuator, in such a way that an overall wheel shape is changed from an overall round shape to an elongated shape.

14. The automotive vehicle wheel and brake system according to claim 13, wherein the wheel comprises at least three of the wheel segments that are configured such that at one of the wheel segments is configured to be radially extensible or retractable relative to at least one other of the wheel segments.

15. The automotive vehicle wheel and brake system according to claim 14, wherein at least two of the segments are configured to be radially extensible or retractable together by the deforming actuator so as to both gain a different radial length than at least one other of the wheel segments.

16. The automotive vehicle wheel and brake system according to claim 13, wherein the wheel segments are surrounded by a common deformable locking ring, the locking ring defining an outer shape of the wheel, the locking ring having a round shape in a first position of the deforming actuator, and the locking ring having an elongated shape in at least another position of the deforming actuator.

17. The automotive vehicle wheel and brake system according to claim 16, wherein which all of the wheel segments are radially movable, and wherein the wheel and brake system further comprises: two radially expandable legs, each leg end constantly pointing, from a wheel axle leg end towards an outer leg end, at a fixed slanted direction towards the ground, a split drum configured to rotate around the expandable legs so that each outer leg end constantly points towards at least one of the wheel segments, and is configured be pressed toward the outside of the wheel against the expandable leg, wherein the electronic system is configured to trigger the deforming actuator system to expand the expandable legs during a braking process when the position of the split drum is within a predefined group of angular positions.

18. The automotive vehicle wheel and brake system according to claim 17, further comprising: a rotating hub configured to maintain the wheel segments rotating around the wheel axle; and a group of radial pressing struts to connect the hub and each wheel segment, and to apply a radial force between the hub and each wheel segment, so as to press each wheel segment radially against the deformable locking ring.

19. The automotive vehicle wheel and brake system according to claim 18, further comprising: a disk braking system configured to stop rotational motion of the hub around the wheel axle; and an angular detection means for estimating an angular position of at least one of the wheel segments relative to one of the legs, and for determining at which moments an expansion of the legs makes the legs press on only one of the wheel segments.

20. An automotive vehicle comprising: at least two of the automotive vehicle wheel and brake system according to claim 11 as front wheels of the vehicle or as rear wheels of the vehicle.

Description

[0049] The present invention and its advantages will be better understood upon reading hereafter the detailed description of one particular embodiment illustrated by the appended drawings, this embodiment being cited as a non limiting example.

[0050] FIG. 1 is a schematic description of a wheel and brake system according to the invention;

[0051] FIG. 2 shows a vertical section of a portion of wheel belonging to the system of FIG. 1;

[0052] FIG. 3 is an exploded view of a wheel belonging to the system of FIG. 1.

[0053] FIGS. 4a and 4b illustrate one possible deformation pattern of a wheel belonging to an embodiment of the present invention;

[0054] FIGS. 5a and 5b illustrate another possible deformation pattern of a wheel belonging to an embodiment of the present invention;

[0055] As illustrated on FIG. 1, a wheel and brake system 1 comprises:

[0056] an axle end 2, attached to the vehicle body, and configured to impose the rotational axis of the wheel,

[0057] a central hub, rotating around the axle end,

[0058] an angularly split drum 6, comprising a number of wheel segments 20, here 10 wheel segments of same angular amplitude,

[0059] radial pressing struts, here radial springs 5, for exerting a radial force between the hub 4 and wheel segments 20; The springs may be partially inserted into the hub at one end, and/or into wheel segments at the other end; They may, alternatively, be placed around protruding portions of either hub and/or wheel segments; There may be a radial guidance by hub portions penetrating wheel segments, or the opposite.

[0060] The wheel system also comprises a deformable locking ring 17, here comprising a metallic, elastomeric or composite locking element 7, and also comprising a tire circling the locking element 7 and the wheel segments 20. The locking element here counterbalances the forces exerted by the springs 5, and also offers support for the tire 8.

[0061] The wheel and brake system comprises two actuator legs 3, with an inner end attached to the axle end , and an outer end equipped with a roller 16 placed so as to press onto one of the wheel segments, when the leg is expanded. The leg direction is at a slant, that is forming an angle a with the vertical direction of the vehicle. The angle may be comprised between 20 and 90 for example.

[0062] The wheel and brake system comprises an electronic system 10, which is configured to detect a need for braking and/or a braking signal emitted from a braking pedal 13.

[0063] The electronic system comprises a wheel speed estimator 11 which is configured to measure, or to calculated, a rotational speed of the wheel. The electronic system also comprises wheel position sensor systems 12 (illustrated on FIG. 2). When braking is requested, the electronic system may, at a specific time during the braking process, trigger an expansion l(t) of the actuator legs 3, taking into account a rotation speed (t) of the wheel, and an angular position (t) of the wheel. The expansion of actuator legs 3 provokes a change in the overall outer shape of the wheel, increasing contact surface between tire and road. This secondary braking process can be triggered when the wheel has already been slowed down by a main braking process, for instance by a disk braking process.

[0064] FIG. 2 shows a vertical section of a portion of wheel belonging to the system of FIG. 1; Some elements are already depicted on FIG. 1, same elements being designated by same references.

[0065] As can be seen on FIG. 2, each wheel segment may have a pressing surface 14 facing the center of the wheel, and circling around the rollers 16 of the outer leg ends, so as to contact the rollers, avoiding brutal contact between leg and wheel segment when the leg is triggered to expand. The wheel segment itself may have a centering portion 15 extending to the inside of the wheel, the centering portion 15 coming closer to the wheel axle, than the contacting radius imposed by the outer radius of the outer leg ends.

[0066] The wheel may be equipped with a primary braking system, here a braking system with a disk 9.

[0067] In order to improve contact surface with the ground, leg expansion is tailored to change the overall shape of the wheel, and the overall shape of locking element 7 and split drum 6 underneath.

[0068] FIG. 3 is an exploded view, to better distinguish between the different components of the wheel, allowing to get an actively deformable wheel.

[0069] Some elements are already depicted on FIGS. 1 and 2, same elements being designated by same references. Elements 2, 3, 16 on the right of the image have a constant angular position relative to axis x corresponding to geometrical axis of the wheel axle. Elements 4, 5, 6, 12, 7, 8 on left side of the image, as well as the rotating brake disk 9, rotate around axis x during driving of the vehicle.

[0070] As can be seen on FIG. 3, the leg system 3, or more generally the deforming actuator 3, is preferably placed along the axis x of the wheel, so as to be closer to the vehicle central frame, than the rotating brake disk 9. In this way, the deformable wheel system can be delivered as a whole system preassembled around a central stub axle. Both the brake disk 9 and actuator system 3 may be delivered pre-mounted around the stub axle. After the stub axle has been assembled onto the vehicle frame, the actuator system 3 may then be blocked in rotation relative to the vehicle frame. For instance, long screws (not depicted on the pictures), traversing the frame and the deforming actuator system, may be inserted to this purpose.

[0071] FIG. 4a illustrates a wheel shape during driving, FIG. 4b illustrates the same wheel portion during braking. All pressing struts are here elongated once the legs are triggered; the shape changes from round on FIG. 4a to elliptic on FIG. 4b. Some elements are already depicted on FIG. 1, same elements being designated by same references.

[0072] FIG. 5a illustrates, in a different embodiment, a wheel shape during vehicle driving, FIG. 5b illustrates the same wheel portion during braking. Once the legs are triggered to extend, vertical pressing struts get shorter, whereas lateral struts are elongated. The shortening of the vertical legs may be obtained thanks to the reaction of the deformable locking element 7 to the pressure exerted by the actuator legs 3, by choosing an appropriate a angle of the legs. In this embodiment, the wheel shape changes from round on FIG. 5a to oval on FIG. 5b. Some elements are already depicted on FIG. 1, same elements being designated by same references.

[0073] The braking system and associated braking process according to the invention, has been estimated to reduce emergency braking distance to about a half of braking distance without active wheel shape change, for initial vehicle speeds comprised between 50 km/h and 200 km/h.