The invention concerns a bearing, a braking assembly comprising such a bearing, and an application of these assemblies to the measurement of the torque and the forces applied to one or each of the wheels of a vehicle and to the regulation of at least one control of the vehicle.
Bearings are already known of the type comprising a fixed raceway intended to be associated with a fixed structure, a rotating raceway intended to be associated with a rotating member, and rolling bodies disposed between them, in which the fixed raceway comprises means of fixing the bearing to a fixed structure.
When it is wished to know forces applied by the fixed structure to the rotating structure, it is known that attached parts forming measuring units can be disposed at the connection between the fixed raceway and the fixed structure.
The document EP-A-0 432 122 illustrates this technology, providing a measuring unit rigidly fixed to the fixed raceway, this measuring unit comprising an annular support and a plurality of sensors associated with the support in predetermined orientations with respect to the axis of rotation.
This type of technology has a certain number of drawbacks.
This is because the presence and multiplicity of the attached measuring units make the assembly of the bearing tricky and complex.
The fixed raceway, by trapping the measuring units when the bearing is assembled, subjects them to prestressing which is detrimental to the subsequent measurements of forces.
Moreover, when it is wished also to know the braking torque applied to a wheel by means of a brake calliper, this type of technology cannot be envisaged.
The invention therefore aims to remedy these drawbacks by proposing a bearing which comprises, in an integrated fashion, deformation zones instrumented by sensors, and which makes it possible to measure both the forces resulting from the static and dynamic behaviour of the vehicle and the braking torque exerted on a wheel of the vehicle.
For this purpose, and according to a first aspect, the invention proposes a bearing of the type comprising a fixed raceway intended to be associated with a fixed structure, a rotating raceway intended to be associated with a rotating member and rolling bodies disposed between them, in which the fixed raceway comprises first means of fixing the said bearing to the fixed structure, the fixed raceway comprising at least one elastic deformation zone able to be deformed under the action of forces exerted on the said bearing, at least one sensor able to measure the said forces being associated functionally with the said elastic deformation zone.
This bearing can also comprise second means of fixing a device intended to apply a force to the rotating member associated with the rotating raceway.
The elastic deformation zone is located for example in the vicinity of the first and/or the second fixing means.
According to one embodiment, the sensor or sensors located in the vicinity of the first fixing means are arranged so as to measure the forces applied to the first fixing means, and their respective moments, in three orthogonal directions forming a trihedron together.
The sensor or sensors located in the vicinity of the second fixing means can for their part be arranged so as to measure the forces applied to the second fixing means, and their respective moments, in three orthogonal directions forming a trihedron together.
According to one embodiment, the bearing comprises a flange forming the first fixing means, this flange projecting radially from the fixed raceway, and comprising two flat faces extending radially and connected together by a circumferential face.
This flange comprises for example first radial projections in which axial holes are formed for fixing the bearing by screwing to the fixed structure, two adjacent projections being separated by a zone with a lesser axial and/or radial direction forming an elastic deformation zone, on which the sensor or sensors are disposed.
For example, the flange comprises four first projections disposed substantially at 90xc2x0 with respect to each other, defining between them four elastic deformation zones on each of which at least one sensor is disposed.
Moreover, the flange can comprise second radial projections forming second means of fixing to the bearing a device intended to apply a force to the rotating member associated with the rotating raceway, the projections comprising a base zone and an end zone.
These second projections comprise for example axial holes for fixing the said device by screwing, located in the end zone, at least one sensor being disposed on or in the vicinity of the base zone, this forming an elastic deformation zone.
According to one embodiment, two sensors are disposed on the circumferential face, on each side of each radial projection, and/or at least one sensor is disposed on the transverse faces of the flange.
Preferably, one radial dimension of the second projection is greater than a radial dimension of the first projections.
According to one embodiment, the flange comprises:
four first projections disposed substantially at 90xc2x0 with respect to each other, defining between them three elastic deformation zones on each of which at least one sensor is disposed; and
two second projections located between two adjacent first projections, each second projection being provided with at least one sensor.
As a variant, openings are formed in the first and/or second projections, sensors being disposed on the internal faces of the openings.
According to one embodiment, at least one sensor is disposed on, or comprises, an intermediate part fixed to an elastic deformation zone by nesting, welding, gluing or the like.
According to a second aspect, the invention proposes a braking assembly comprising a bearing as described above, and a brake calliper associated with it by means of second fixing means, the calliper being separate from the fixed structure.
According to one embodiment, this assembly also comprises a brake disc associated with the rotating raceway, inserted between the jaws of the calliper so that the latter applies to it a braking force by the bringing together of the jaws.
According to a third aspect, the invention proposes an application of these assemblies to the measurement on the one hand of the braking torque of a vehicle and on the other hand of the longitudinal, transverse and vertical forces exerted on one or each of its wheels, in which an assembly is associated with one or each of the wheels of the vehicle, the torque being measured by means of sensors located in the vicinity of the second fixing means and the forces being measured by means of the sensors located in the vicinity of the first fixing means.
According to one embodiment, in which a control device collects the measurements of the braking torque and/or of the forces exerted on one or each of the wheels, this device being arranged so as to regulate at least one command for dynamic control of the vehicle, notably the braking, the acceleration, the steering or the suspension according to the said measurements.