Flanged wheel hub bearing provided with a sensor

Abstract

A wheel hub bearing for motor vehicles including a rotatable hub provided with a flange for the engagement of the hub to a wheel of a vehicle and provided with a radially outer free portion and a bearing unit provided with a radially outer ring for the engagement of the wheel hub bearing to a knuckle of the vehicle and a radially inner rotatable ring angularly connected to the hub. Furthermore, the wheel hub bearing has a device for detecting a vehicle parameter and provided with an encoder and a sensor in communication with the encoder. The encoder is ridgidly coupled to the radially outer free portion of the flange to jointly rotate with the hub.

Claims

1. A wheel hub bearing for motor vehicles, the wheel hub bearing comprising: a rotatable hub provided with a flange for the engagement of the hub to a wheel of a vehicle, a radially outer free portion, and a bearing unit having a radially outer ring for the engagement of the wheel hub bearing to a knuckle of the vehicle and a radially inner rotatable ring angularly fixed to the hub, a device for detecting a vehicle parameter being provided, the device including an encoder and a sensor with magnetic effect, the encoder is configured to generate magnetic signal, the sensor being in communication with and axially spaced from the encoder and facing the encoder, and a protective cap coupled to a radially outer free portion of the flange, wherein the protective cap comprises a radially extending sidewall having an axially inner side surface and an axially outer side surface, wherein the axially outer side surface is axially spaced from and faces an axially inner side surface of the flange, and wherein the encoder is mounted on a radially outer end of the axially inner side surface of the radially extending sidewall at the radially outer free portion of the flange wherein the encoder is engaged with the flange directly through the protective cap, so that the protective cap and encoder rotate with the same rotational speed of the hub, wherein the encoder is solely coupled to the rotatable hub though the protective cap's coupling to the radially outer free portion of the flange.

2. The wheel hub bearing of claim 1, wherein the device for detecting a vehicle parameter detects a rotational speed with a speed sensor, wherein the value of a nominal reading diameter (D) of the speed sensor ranges between 130 mm to 150 mm.

3. The wheel hub bearing of claim 2, wherein the intermediate element is a block, separated or integrated to the knuckle of the suspension.

4. The wheel hub bearing of claim 3, further comprising a plurality of discharge windows in the cylindrical sidewall.

5. The wheel hub bearing according to claim 1, wherein a number of poles pairs with inverse polarity accommodated on the encoder ranges between 120 to 160.

6. The wheel hub bearing of claim 1, wherein the sensor is configured to be mounted on the knuckle of a vehicle suspension by interposing an intermediate element and the axial position of the sensor is adjustable by means of tightening elements configured to adjust the axial position between the sensor and the encoder.

7. The wheel hub bearing of claim 1, further comprising a protective screen configured to isolate an interior of the bearing, wherein the protective screen has an elastomeric lip.

8. The wheel hub bearing of claim 1, wherein the protective cover further comprises a cylindrical sidewall coupled to a radially outer free portion of the flange, wherein the radially extending sidewall extends radially inwardly from the cylindrical sidewall.

9. A wheel hub bearing for motor vehicles, the wheel hub bearing comprising: a rotatable hub provided with a flange for the engagement of the hub to a wheel of a vehicle, a radially outer free portion, and a bearing unit having a radially outer ring for the engagement of the wheel hub bearing to a knuckle of the vehicle and a radially inner rotatable ring angularly fixed to the hub, and a device for detecting a vehicle parameter being provided, the device including an encoder and a speed sensor with magnetic effect, the encoder is configured to generate magnetic signal, the sensor being in communication with and axially spaced from the encoder and facing the encoder, wherein the encoder is rigidly coupled to the radially outer free portion of the flange to jointly rotate with the hub, wherein the encoder is engaged with the flange through a protective cover; wherein the encoder is mounted on a radially outer end of an axially side surface of the protective cover rigidly coupled to the flange and extending around a lateral surface of the radially outer ring, so that the protective cover rotates with the same rotational speed of the hub, wherein the protective cover further comprises an axially outer side surface axially spaced from and facing an axially inner surface of the flange; wherein the speed sensor is configured to be mounted on the knuckle of a vehicle suspension by interposing an intermediate element and the axial position of the speed sensor is adjustable by means of tightening elements configured to adjust the axial position between the speed sensor and the encoder, wherein the encoder is solely coupled to the rotatable hub though the protective cap's coupling to the radially outer free portion of the flange.

10. The wheel hub bearing of claim 9, wherein the value of a nominal reading diameter (D) of the speed sensor ranges between 130 mm to 150 mm.

11. The wheel hub bearing according to claim 9, wherein a number of poles pairs with inverse polarity accommodated on the encoder ranges between 120 to 160.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) The invention will now be described with reference to the accompanying drawings, which illustrate some examples of non-limiting implementation, in which:

(2) FIG. 1, in a partial axonometric view, shows a wheel hub bearing provided with a device for detecting the rotational speed, according to an embodiment of the invention,

(3) FIG. 2, in a partial axi-symmetrical section, shows the wheel hub bearing provided with the device for detecting the rotational speed of FIG. 1, and

(4) FIG. 3, in a partial axi-symmetrical section, shows the wheel hub bearing provided with the device for detecting the rotational speed of FIG. 1, according to an alternative embodiment.

DETAILED DESCRIPTION

(5) With reference to the aforementioned figures, 10 indicates as a whole a wheel hub bearing according to a preferred embodiment of the invention. As stated in the introduction, the invention is applicable not only to the configuration described below but more generally to any wheel hub bearing for motor vehicles.

(6) The assembly 10 comprises a hub 20 preferably, but not necessarily, rotatable and a bearing unit 30. The hub 20 is configured to also assume the function of a radially inner ring of the bearing.

(7) In all the present description and enclosed claims, terms and wording, indicating positions and directions, as “radial” or “axial” have to be understood as referred to the rotation axis X. Wording as “axially inner” or “axially outer” have to be referred to a mounting condition of the hub-bearing unit on the motor vehicle.

(8) The bearing unit 30 comprises a radially outer ring 31, stationary, provided with respective radially outer raceways, at least one radially inner ring 20, 34, provided with respective radially inner raceways and two rolling elements crowns 32, 33, in this example balls. The axially outer rolling elements crown 32 is interposed between the radially outer ring 31 and the hub 20, having a radially inner ring function, while the axially inner rolling elements crown 33 is interposed between the radially outer ring 31 and radially inner ring 34. For simplicity of graphic representation, references 32, 33 will be attributed both for the individual balls and the balls rows and in particular with 32 will be referenced the axially outer balls row or single ball, while with 33 will be referenced the axially inner balls row or single ball. Again, for simplicity, the term “ball” can be used in the present description instead of the more generic “rolling element” term (and the same numeral reference will also be used in the attached drawings). It is always understood that instead of the balls any other rolling element can be used (for example, rollers, conical rollers, small rollers, etc.).

(9) The bearing unit 30 is sealed by suitable sealing elements 35, 36 which are cassette sealing elements, as in the prior art. The rolling elements of the crowns 32, 33 are held in position by corresponding cages 39, 40.

(10) The hub 20 defines in its axially inner end a rolled edge 22 which is configured for axially preloading the inner ring 34. The hub 20 also has an axially outer flange 23. The flange 23 has a plurality of axial fixing holes 24. These holes are the seats for the same number of fixing means (for example stud bolts, not shown in the figure) which connect in a known manner an element of the motor vehicle wheel, for example the brake disc (also of known type and not shown in the figure), at the hub 20. The flange 23 is also provided with a radially outer free portion 23′.

(11) The bearing is equipped with a device 50 for detecting a parameter of the motor vehicle, for example the rotational speed of the rotatable ring of the bearing unit 30, and is 30 provided with an encoder 51 and a sensor, for example a speed sensor 52 with magnetic effect.

(12) The solution according to the present invention aims to improve the resolution and accuracy of the speed sensor signal. In other words, what we want to achieve is the possibility of housing a greater number of poles pairs on the encoder, increasing the nominal reading diameter of the sensor.

(13) Therefore, according to the present invention, the encoder 51 is mounted at the radially outer free portion 23′ of the flange 23 of the wheel hub assembly 10, steadily engaged with the flange 23. More specifically, the encoder is mounted on the radially outer side surface 53′ of a protective cover 53, which is steadily engaged with the radially outer free portion 23′ of the flange 23.

(14) The cover 53, object of a previous patent application by the writer, ITTO2011A000708, is mounted on the flange 23 so as to rotate together with the hub 20 and extends around the lateral surface of the radially outer ring to circumscribe the gap 54 from the outside of the bearing unit 30. The cover is also provided with a plurality of discharge windows 55 passing through for the evacuation of any moisture that has accidentally entered or formed inside the cover 53.

(15) In this way, by mounting the encoder 51 on the side surface 53′ of the cover 53 instead of on the axially inner ring 34 or on an element connected thereto, as per the prior art, a nominal reading diameter D of the sensor is obtained, value almost double with respect to the nominal reading diameter d obtainable from solutions according to the prior art. As a consequence, also the number of poles pairs with inverse polarity lodged on the encoder will be greater and almost double compared to that of the known embodiments.

(16) To give an exemplifying and non-limiting idea, according to the known art, the reading diameter d is of the order of 80 mm and such an encoder allows the housing of 48 poles pairs. Vice versa, according to an embodiment of the present invention, the reading diameter D is about 130mm and the relative encoder 51 allows to house about 126 poles pairs.

(17) Preferably, in order to meet the needs of “premium” range cars, where autonomous driving or at least assistance during parking maneuvers are rapidly spreading, experimental evidence has shown that, in order to obtain high resolution of the signal and greater accuracy in reading, an optimal range for the value of the nominal reading diameter D is between 130 mm and 150 mm, allowing the lodging of a number of poles pairs between 120 and 160.

(18) Advantageously, the speed sensor 52 facing the encoder 51 is assembled on the knuckle 56 of the suspension by interposing an intermediate element 57. The axial position of the sensor is adjustable by means of clamping or tightening elements 58, in particular bolts. The intermediate element 57 may be a block which is separate or integrated with the knuckle of the suspension. In this way, the axial dimension of the air gap between the sensor 52 and the encoder 51 can be adjusted according to the signal reading requirements.

(19) An undoubted technical advantage of this solution is that it is no longer necessary to house the encoder on the radially inner ring 34. This advantage further simplifies the design of the bearing unit.

(20) In fact, as can be seen in FIG. 3, since there is no longer an encoder, the axially inner cassette seal 36 is not even necessary since it is sufficient to provide a protective screen with an elastomeric lip to isolate the inside of the bearing unit.

(21) Therefore, with the present invention numerous and significant advantages are achievable. First of all, the speed sensor will have greater accuracy and resolution with this ensuring to identify a more precise position of the vehicle as well as its speed.

(22) Furthermore, the use of such a solution requires the adoption of the protective cap which guarantees an excellent protection of the entire axially external area of the bearing and in particular of its cassette seal.

(23) Finally, the design of the bearing unit can be simplified and consequently be less expensive due to the fact that the concept of cassette seal can be eliminated by introducing a simpler protective screen.

(24) Other than the embodiments of the invention, as above disclosed, it is to be understood that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.