Automobile Wheel Hub

The invention pertains to an automobile wheel hub comprising a roller bearing in a housing for said hub and an information sensor, the coding element of which rotates integrally with the hub and moves in front of a stationary sensor.

French Patent No. 2,570,143 describes a hub of this type, in which the coder is fixed to the outer periphery of the hub, essentially in the plane of a raceway of the roller bearing.

When the hub is integral with a brake drum which defines, together with the outer periphery of the hub, the brake housing, the coder can no longer be placed on the hub. Moreover, when the roller bearing is a conventional roller placed in a hub attached to the steering knuckle onto which the brake plate is secured, the sensor can no longer satisfy the above-mentioned arrangement because of the small amount of space available.

The principal task of the invention is, therefore, to provide a wheel hub for drum brakes which facilitates the installation of a speed sensor with the goal of allowing, for example, the implementation of an anti-wheel locking and/or anti-skid device for vehicles equipped with drum brakes.

According to the invention, the coder is preferably integrated into the seal of the roller bearing in such a way that it is essentially flush with the plane of one lateral face of the hub facing the longitudinal plane of the vehicle; the sensor is integral with a support, which is stationary with respect to the wheel, is coaxial to the coder in a radial position essentially equal to the value of the radius of the coder element and shifted longitudinally by a maximum value corresponding to the air gap allowed by the technology of the sensor used.

An embodiment of the hub is described below with reference to the attached drawings, in which:

FIG. 1 is a view, partly in cross-section, taken along line 1--1 of FIG. 2 of a drum brake hub mounted on an undriven wheel spindle of an automobile;

FIG. 2 is a front view of the hub along line 2--2 of FIG. 1 showing the sensor and sensor support plate;

FIG. 3 is a partial view of details of the preferred embodiment of FIG. 1 on an enlarged scale; and

FIG. 4 is a partial detailed view on an enlarged scale of a further preferred embodiment of the invention.

In the various figures, like parts are referred to by like numbers.

An undriven wheel hub comprises a spindle 10 projecting from a steering knuckle 11 with, at its threaded end, a nut 12 and a washer for axially preloading a bearing 13, which can have two rows of rolling elements 14 between an inner ring 15 split into two parts and an outer ring 16, the ends of which each carry a seal 17.

Bearing 13 can consist of two conventional bearings without going beyond the context of the present invention.

Bearing 13 is placed in the bore 21 of housing 22 which extends radially into a brake drum 23, the outer face of which carries studs (not shown) for attaching the vehicle wheel

Outer ring 16 of the bearing is held radially in housing 22 by clamping and held axially between a shoulder 24 on housing 22 and a retaining washer in bore 21.

Referring to FIG. 3, a device for sensing information, especially for sensing the rotational speed of the wheel consists of a coder element 26 rotating integrally with housing 22 and a stationary sensor 27. It is advantageous for coder element 26 to be integrated into seal 17 at the time the latter is molded, in such a way that it is positioned opposite the sensor. The coder element is flush with the outer lateral face of the seal. According to a variant of the invention (FIG. 4), a support 28 of coder 26 is a ring with a circular groove, in which coder 26 is housed; this support is installed in bore 21 so that the coder is essentially in the plane of lateral face 40. For this purpose, support 28 has a radial annular rim 30 clamped between an axial end of bearing ring 16 and shoulder 24.

The coder and its support can be connected by other means without going beyond the scope of the invention.

Support 29 for sensor 27 consists of a plate, made preferably of a non-magnetic material, connected to a fixed ring 30', mounted on spindle 10 between inner ring 15 of the bearing and steering knuckle 11. Support 29 is configured in such a way as to ensure its angular position with respect to the brake plate. In the example shown in FIG. 2, support 29 has a series of recesses 31, which perform this function by interacting with attachment bolts 33 of brake plate 32. Moreover, support 29 is designed in such a way that there is only one single angular positioning possibility, namely, that which favors correct operation of sensor 27. To make it independent of the variation in the air gap between coder 26 and sensor 27 resulting from the angular camber of the wheel along its vertical plane of symmetry while passing through curves, sensor is positioned on a horizontal plane along section line 1--1 of FIG. 2.

Support 29 for sensor 27 has the additional function of carrying a printed circuit 27', comprising elements to protect sensor 27 against overvoltages and polarity reversals. It also effectively holds a cable 27", which carries signals to the processing unit. The cable passes through brake plate 32 in cooperation with an element 34, which provides a seal against the penetration of contamination into the brake enclosure.

The invention is in no way limited to the embodiment described and represented here by way of example. In particular, the invention embraces technical means equivalent to the means described or combinations thereof to the extent that the latter are implemented in the spirit of the invention or carried out in the context of a measurement of information concerning the speed of a rotating hub.