GB2207470A

GB2207470A - A sealing assembly for interposition between two members in relative rotation operable to permit detection of the speed of relative rotation between them, and a bearing for supporting a vehicle wheel, provided therewith

Info

Publication number: GB2207470A
Application number: GB08810275A
Authority: GB
Inventors: Roberto Moretti; Angelo Vignotto; Angelo Varvello
Original assignee: RIV SKF Officine di Villar Perosa SpA; RIV Officine di Villar Perosa SpA
Current assignee: SKF Industrie SpA
Priority date: 1987-07-24
Filing date: 1988-04-29
Publication date: 1989-02-01
Also published as: GB8810275D0; FR2618516A1; DE3819619A1; ES2009983A6; IT1211239B; FR2618516B1; GB2207470B; IT8767650A0

Description

14 1 1 1 -.1 2267470 1 A SEALING ASSEMBLY FOR INTERPOSITICN EE.T.WEEN TWO

MEMBERS IN RELATIVE ROTATION OPERABLE TO PERMIT DETECTIO-1 CF THE SPEED OF RELATIVE ROTATION BETWEEN THEM, AND A BEARING FOR SUPPORTING A VEHICLE WHEEI, PROVIDED THEREWITH The Present invention relates to a zealing asse.mbly which car, be interposed between two members in re-"a4,--ive rotation, for example the rings of a rolling element bearing, and which can permit the speed of relative rotation between them to be detected; further the inventon also relates tc a rc'"4ng elemen' '-ea--1r.g -fcr supporting the wheel of a vehicle prcv-Jded with t-he said sealing assembly.

It is known that currently special control c-rcu-'L4--s of the type known as AES are installed for -thle purpose of preventing locking oil the wheels of the vehicle during braking; these circuits consist, as is known, of ar. hydraulic operative part. acting by means of valves an the no braking circuit, and an electronic control part able t-cause the operative part to intervene when a differential variation in the speed of rotation of the wheels of each axle of the vehicle greater than a predetermined threshold is detected; these speed variations are "5 detected by an appropriate known circuit making use of electromagnetic sensors, at least cne for each wheel of 2 the vehicle, each of which emits a pulse signal proportional to the speed of rotation of the wheel controlled by it; this pulse signal is obtained in the majority of cases by mounting, usually on the wheel support beariig, a toothed"element known in the art as a "phonic wheel" or "impulse ring"; this element essentially comprises a flange of ferromagnetic material fixed for rotation with the wheel and provided with a toothed ring in correspondence with which the sensor is mounted; during rotation oil the wheel, therefore, the alternatiot past the sensor Cl. solid' parts const-Tituted by the teeth and voids constituted by the spaces bet-ween the teeth causes a periodic variation in the air gap between the flange and sensor and, therefore, a periodic variation in the magnetic field with consequent generation by 'he sensor of a periodic signal.

the frequency of which is propor.tional to the speed of rotation.of the wheel.

one disadvantage of the above described detection system lies in the large dimensions and weight c..E the phonic wheel and in its cost whien is also rather high. Albove all, however, the system.described involves the disadvantage of becoming unreliable after a relatively short period of-use in that ferromagnetic dust prcduced by wear of the braking seals become mixed with road mud 0. -- 1. 1 1, 1.1 (0 3 which comes into contact with the vehicle suspension in operation, filling the spaces between.11..'-.e te--"--h of the phonic wheel and therefore causing a fall or attenuation in the signal produced by the sensor for which reason it becomes necessary periodically to renew the efficiency of the system by frequently washing the wheel-suspension units.

The object of the invention is that of providing a sealing assembly which can be fixed to a rotating member, in particular to a ring of a bearing for supporting a vehicle wheel, and operable simultaneously to exert a sealing action and to allow detection of the angular velocity of the rotating member to which it is fixed by means oil a system for enerating magnetic pulses entirely similar to that currently in use in ABS systems so as to be usable in 'place of the phonic wheel and tb.e sensors currently used in this system.

J; The said object is achieved by the invention, which relates to a sealing assembly for interposition between two relatively rotatable members, in Particular between the rings of a roller element bearing fcr supporting a vehicle wheel, characterised by the fact that it comprises a first rigid screen which can be fixed for rotation with one o the said'members which is a - 4 with respect to the other, which first screen carries a reference element fixed for rotation therewith and provided with a ring of depressions in a regular succession, a rigid second screen which can be fitted onto the other, of the said members and fixedly ca.-rying a sensor disposed in position such as to be disposed, in use, facing the said reference element, and an annular elastomeric sealing element carried by one of the said rigid screens and able to cooperate in use with the other of the said screens to define between them and with the said members on which the screens are fitted, a fluid tight closed chamber housing the said sensor and the said reference element.

For a better understanding of the invention there is now given a nonlimitative description of va.rlous embodiment-s, with reference to the attached drawings, in which:

Figure 1 illustrates a support bearing for a vehicle wheel, not illustrated, provided with a sealing assembly according to the-.-4nv6ntion.. _ i Figure 2 illustrates on an enlarged scale and in sectioned side view a detail of the sealing assembly according to the invention mounted on the bearing of Figure 1; and 2.

1.

1 1 0 Figures 3 and 4 illustrate two possible variants of the sealing assembly of Figure 2.

With reference to Figures 1 and 2 a rolling element bearing of knawn type able to support a wheel, not illustrated, of the. vehicle, also known and not illustrated for simplicity, is generally indicated with the reference numeral 1; the bearing 1 comprises an outer ring 2, an inner ring 3 and'a plurality of rolling bodies 4 grouped in two adjacent rings and interposed between the rings 2 and 3 to render these relatively rotatable with respect tc'one another with low friction; one of the rings, in this case the outer ring 2, is provided with an attachment flange 5 for the said wheel, and the annular space between these, in which the rolling element bearings are housed, i closed from the outside by a seal 6 cf known type and by a sealing assembly 7 of dculle screen type illustrated only schematically in Figure 1 and in detail in Figure 2, disposed c.-i the side opposite i the flange 5 and including a first rigid scree-n C preferably made in sheet metal and fitted onto the ring 2, fixed to it externally, arid a second rigid screen 9, also preferably made of sheet metal, which is fitted onto the ring 3; in particular this latter, which is preferably made from a pair of adjace.nt provided on the side opposite the flange 5 with a is 1 6 portion 10 for mounting one of the screens 8 and 9, in particular for the screen 9, which projects axially out from the outer ring 2, whilst this latter is provided on its outer side surface 11 with an annular groove 12 for receiving the-screen 8; this, according to the invention, is constituted by a.cup-shape sheet metal element having an end rim 13 swaged into the annular groove 1127, whilst the screen 9 is closely fitted onto the mounting portion 10 of the inner ring 3 within the said cup-shape element 8 cpposite a through hole '14 passing through this latter anc of a di=ameter such as to allow the screen 9 pass through it; the cup-shape screen element 8 a cylindrical side wall 15 fitted on41---the surface 11 of the ring 2 coaxially therewith, and a bcl"-cm wall 16 provided centrally with a hole 14, which is coaxial with the wall 15 and with the rest of the screen 8; according to the invention it carries, for rotation therewith, a ferromagnetic element provided in a ring with a regular succession of depressions 18, which is constituted by a i cylindrical internally toothed ring 1,9 fitted against an inner surface 20 of the side wall 15 of it-he cup-shape element 8 coaxial therewith., which rIng lg'is, in use, as is illustrated in Figure.2, able to be clamped between the bottom wall 16 of the cup-shape element 8 and an end face 21 of the radially outer member of those between which the sealing assembly 7 is interposed, in this- case 1 I ' 1.; 7 the ring 2.

The screen.9 is constituted by an annular sheet metal element shaped in radial section with a substantially L-shape profile which is mountable on the portion 10 of the ring 3, projecting with respect to the face 21, and which is provided, according to the invention with a sensor 22 of known type (for example a magnetic sensor) fixed for rotation therewith and disposed in a position such as to be disposed, in use, facing the reference element 19..(for example made cf ferromagnetic material); this, in substance, defines a phonic wheel cf 1--ncwn type arid, being fitted by the screen 8 to a rotat-ing member such as the ring 2, permits in use the detection, by the sensor 22, of the angular velocity of the ring 21 and, in this case, of the wheel fixed to it securely through the flange 5 in that, because of the relative motion between the rings 2 and 3, the passage of the teeth and the voids constituted by the interdent-al spaces 18 in front of the 1 sensor 22, usually constituted by a simple electromagnet, makes it possible to induce in this a magnetic field variation because of the v_, ari&ticns in.thelalr gap, such as to generate a pulse signal which the sensor 2-1 can then transmit in.a known way, not illustrated for simplicity, for example through appropriate wires passing out through the sealing assembly 7 through the screen 9 r. A--1 1 1 8 and the hole 14, to a central control unit, for example of an ABS installation. The sealing assembly 7 according to the invention finally includes an elastomeric annular sealing element 23 carried by one of the screens 8 and 9, but preferably, by that provided with the sensor 22 and therefore, in the illustrated example, by the screen 9, which is able to cooperate in use with the other screen (screen 8) to define between them and with the members on which the screens 8 and 9 are fitted (rings 2 and 3) an annular ch-amber ^44 closed in a fluid tight sealing manner by the elaptomeric element 23 and housing, acc--rd--'ng to the invention, both the sensor 22 and the reference element 19 cooperating with it. In the embodiment illustrated the element or screen 8 is provided on its bottom wall 16, in correspon dence with the hole 14, with an annular indentation 26 the concavIty ef towards the iterior of the element 8 itself; the elastomeric sealing element 23 is constituted by an annular lip shaped, in radial section, with a 1 substantially V-shape which projects from an cuter peripheral rim 27 of the screen 9 and which cooperates by sliding, in use, with the L_ - _;Indentation 26 within the concavity thereof, as well as with the wall portion 16 immediately adjacent to the hole 14 so as to exert a dual sealing action, both radial and axial, against the exterior to close the chamber 24 and consequently prote= 1 9 not only the rolling bodies 4 as in traditional sealing assemblies, but also, according to the invention, the sensor 22 'and associated phonic element 19 with its depressions 18.

Making reference now to Figure 3, where similar cr identical details to those already described are indicated for simplicity with the same reference numerals, the bearing 1 or any pair of relatively rotatable members such as the rings 2 and 3 the speed c.' rotation of one of which it is des2:red tc, ci-:n Le provided in place of the sealing assembly 7 with its variant 7a which is entirely similar e.,ccept for the different form of the screen 9 and the absence of the indentation 26 on the screen 8; in this sea!,4.-,.9 assembly, in fact, the screen 9 is const-ituted by an annular sheet metal element which is substanli-i.ally U-shape in radial section, disposed parallel to the axis of the element 8a and defined by a pair of concentric sleeves 30 and 31 i connected integrally by a common terminal flange portion 32; the sleeve 30 is able to allow the screen 9 to be fitted on the ring 3 projc---"-iry. g with respe=lt to the face 21a within the element 8, whilst the sleeve 31 carries the sensor 22 externally and projecting perpendicularly, on the side opposite that facing towards the inner sleeve 30, and is provided securely with an annular elastomeric 1 sealing element 34 which includes a lip 35 which in use can cooperate by sliding over the surface 21, and an annular protuberance 36 extending radially over the exterior of the sleeve 31 and disposed flush with the bottom wall l& of the element 8 close to a rim 37 of the through hole 14 in such a way as to define a labyrinth seal with the rim 37. In this variant there is thus left, between the sleeves 30 and 311, within the sealing assembly 7a, a large chamber isolated by the lip 35 and which can be utilised for reserves of lubrication grease, as well as.-the chamber 24, also sealingly closed in a fluid tight manrier like the above, housing the sensor 21 and phonic element 19.

Finally, making reference to Figure 4, there is illustrated therein a further variant 7b of the sealing assembly 7, aain illustrated, for simPlicity, on a bearing lb, illustrated only in part, which differs from the bearing 1 only by the fact that the ring fixed to the wheel is now the inner ring 3 (typical case of bearings for the driving wheels of vehicles) which obviously is provided in a known manner,, ifi place of..I-hL- outer ring with the flange 5 which however is disposed on the opposite side from the sealing assembly 7b; similar or identical details to those already described are indicated with the same re. 'eren'ce nu,-,,e--als; In 2, c 1 1 4 1 1 11 particular, in this case the screen provided with the sensor 22 is constituted by a cup-shape element 6b identical to the element 8 of the sealing assembly 7a except for the fact that it is shaped in such a way as to be provided wilth an inwardly projecting sensor 22 on the inner surface 20 of the side wall 15 and with an annular sealing element 40 fixed on the rim 37 of the through hole 14 in the bottom wall 16 and projecting inwardly therefrom; the sealing Is provided with a pair of substantially parallel radial annular lips 41 towards the radially inner screen gh; this iz constituted by an annular sheet metal element cE substantially U-shape in radial secti.on disposed par-='J.Iei to the axis of the cup-shape element 8b and de-fined by a pair of concentric sleeves 42 and 43 connected integrally by a common terminal flange portion 44; the sleeve 412 allows the sceen 9b to be fitted onto the projectinwportion 10 of the rotating ring 3, projecting witInrespect to the face 21 and with respect to _the interior of the cup-shape element Bb; the sleeve 431 on the c-ther b. - and defines the reference ele-.-,.ent cocperat.4ng with the sensor 22 being integ_rally formed w3Lth.theirest of the W screen 9b, which is likewise made of sheet metal, and provided with a plurality of parallel slots 46 formed in a ring defining the depressions 18; the flange pcrtion 44 finally includes an inclined, substantially frustzccnical 1.

v 1 12 part 45 having its narrow end facing outwardly of the chamber 24, defined between the screens 8b and 9'D and the rings 2 and 3,-on which the lip 41 of the elastomeric element 40 slide for fluid tight sealing of the chamber 24.

From what has been described the advantages connected with the sealing assembly according to the invention and with the support bearing for wheels provided therewith will be evident; substantially within the same dimensions required fpr a normal sealing assembly, in fact, _= system for detecting the relative angular velocity cf the members between which the sealing assembly is placed has been successfully positioned, all with a ---av..-.lg of weight due to the reduction of the number of c=ponents with respect to known rotational velocity detection systems, with respect o this, and, especially in the case of applications on vehicle wheels, there is tc-Itall from external contaminants both of the sensor and of the i phonic element so that the measurement system becomes of high reliability and no longer requires frequent maintenance; finally, in t>e case of sealJna assembl--,-zz directly mounted on a bearing, the support unit thus obtained permits..the angular velocity of the member supported by it to be detected in use with extreme precision compared to detection systems in use today in i v 1 13 that the sensor, rather than being mounted on the vehicle in a suitable position which is determined upon assembly thereof, with all the possible positioning errors of an operation performed on the assembly line, or by artisans for systems wkich are not part of the first installation, are mounted with high precision already on the bearing, upon positioning of the sealing assembly.

11 .e i 14

Claims

A sealing assembly for interposition between two relatively rotatable members, in particular between the rings of a rorling elementbea_ring for the support of a vehicle wheel, characterised by the faCt- that it comprises a first rigid screen which can be fixed for rotation with one of the said members which is rotatable with respect to the other, which first screen carries a reference element fixed fcr therewith and provided wIth a regular succession of depression-z in a ring, a rigid second screen which can be fitted ontc the other of the said members and fixedly carrying a sensor disposed in a position such as to be disposedl in use, is facing the said reference element, and an annular elastomeric se.ling element carried by one of' the said rigid screens and able to cooperate in use with the other of the said screens to define between them and with the said members on which the screens are fitted a fluid tight chamber housing the said sensor and the said reference element.
2. A sealing assembly.according to Claim 1, characterised by'the fact that the said annular elastomeric sealing element is carried by the said second screen, together with the said sensor.

t
3. A sealing assembly according to Claim 1 or Claim 2, characterised by the fact that one of the said rigid screens is constituted by a cup-shape element having a the said thereto, radially externally with respect to the other, and a bottom wall provided with a central through hole having diameter such as to allow the other said screen to pass 10 through it.

cylindrical side wall fitted onto a first of members coaxially thereof and fixed securely
4. A sealing assembly according tc Claim 3, characterised by the fact that the said firs" screen is constituted by the said cup-shape element, and by 1Che is fact that the said refe-ence element is constituted by an internally toothed cylindrical ring fitted against an inner surface of the said lateral wall of the cup-,1-ape element coaxially therewith, the said internally toothed ring being able in use to be gripped between the said i bottom wall of the cup-shape element and an end face off:

the said first member.

1
5. A sealing assembly,according to Claim 4, characterised byAhe fact that the said second screen is constituted by an annular element havAing a substantially L-shape in radial section, which is mountable on a second of the said members projecting from the said end face of the said first member and into the interior of the said cup-shape element, this latter being provided on the said bottom wall around the said central through hole with an annular indentation the concavity of which faces towards the interior of the,cup-shape element; the said elastomeric sealing element being constituted by an annular lip having a substantially V-shape radial section projecting from an outer peripheral rim of the said second screen and cooperating, in use, by sliding on the said concavity of the said indentaticn cf the said cup-shape element.
6.. A sealing assembly according to Claim 4, characterised by the fact that the said second screen is constituted by an annular element having a substantially U-shape radiai section disposed parallel to the axis of the said cup-shape element and defined by a pair of concentric sleeves connected integrally by a common terminal flange portion, a first sleeve being able to allow fitting of the said second screen on a second c.' the said members, projecting zitl,- . respect to the said end face of the said first member and within the interior of the said cup-sha pe element, and a second sleeve carrying the said sensor projecting perpendicularly outwardly and being provided fixedly with the said annular sealing 1.

4 17 element, which includes a lip able in use to cooperate by sliding onthe said end face of the first member, and an annular protuberance extending radially over the exterior of the said second sleeve of the second screen and disposed flush with the said bottom wall of the cup-shape element close to a rim of the said through hole W this latter in such a way as to define a labyrinth seal wit'--i the said rim.
7. A sealing assembly according to Claim 3, characteriped by the fact that the said second screen constituted by the said cup-shape element, whizh is provided with the said sensor prJecting inwardly frcm the said lateral wall and with the said annular sealing element fixed so as to project inwardly from the rim cf the said through hole in the said bottom wall, and by the fact that the'said first screen is constituted by an annular element of sheet metal hiving a substantially U-shape radial section disposed parallel to the axis ef the said cup-shape element and defined by a pair of concentric sleeves integrally cennectei by a ccmmcn terminal flange portion, afirst sleeve being able to allow the said first screen to be fitted onto a second of the said members.projecting with respect to the said end face of the said first member and into the interior of the said cup-shape element, and a second sleeve defining . I,.

4 R 18 the said ferromagnetic element being provided with plurality of parallel slots defining the said depressions; the said flange portion of the first screen including an inclined part on which the said elastomeric sealing elemeat slides.
8. A bearing for supporting the wheel of a vehicle and able to permit measurement of the speed of rotation thereof, of the type comprising an cute-r ring, an inner ring and a plurality of rolling bodies interposed between the said rings to render them relatively rotatable with respect to one another with low friction, in which cne of the said rings is provided with an attachment flange for the said wheel, charac"k--er2Lsed by the fact that it includes a sealing assembly according to-any of Claims from 1 to 7 disposed on the side opposite the sa-'d flange and having the said first screen -"--hereof fitted onto that ring of the said bearing provided with the attachment flange for the wheel and the said second screen fitted onto the other of the said rings, the inne-l- ring of the said bearing being provided, on the side opposite the said wheel attachment fla:ige, lwith a mountling portion for receiving one of the said screens extending axially and projecting out from the said outer ring, and this latter being provided on its outer lateral surface with an annular groove for receiving the other of the said 1 l.

4 19 screens of the sealing assembly.
9. A bearing according to Claim 8, characterised by the fact that the said screen of the sealing assembly fitted to thesaid outer ring is constituted by a sheet metal cup-shape element having a rim swaged intc the said annular groove, whilst the other said screen is fitted into the said mounting portion of the inner ring within the said cup-shape element.
10. A sealing assembly substantially as hereinbefore described with reference to, and as illustrated in, Figures 1 and 2 or Figure 3, or Figure 4 of the accompanying drawings.
11. The combination of a bearing and sealing assembly therefor, thecombination being substantially as hereinbefore described with reference to, and as illustrated in, Figures 1 and 2, or Figure 3, or Figure 4, of the accompanying drawings.

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