Title: Bearing unit for the hub of a vehicle wheel equipped with a tire inflating system
Abstract: A bearing unit comprises an outer stationary race (1) with a first inner passage (6) for the air, and two axially adjacent inner half-races (2a, 2b) rotatable with the hub of a wheel. Formed between the inner half-races are essentially radial second inner air passages (7, 71, 72). These passages have surfaces (71d, 72d) inclined forwardly with respect to a direction of rotation (A, B) so as to favor the air flow through the rotating part of the bearing.
Patent Number: 6,896,413 Issued on 05/24/2005 to Zavaglia, et al.
| Inventors:
|
Zavaglia; Luca (Rivoli, IT);
Musso; Michele (Rosta, IT);
Ruetter; Andreas (Pinerolo, IT);
Brunetti; Marco (Turin, IT)
|
| Assignee:
|
SKF Industrie S.p.A. (Turin, IT)
|
| Appl. No.:
|
446915 |
| Filed:
|
May 27, 2003 |
Foreign Application Priority Data
| May 31, 2002[IT] | TO2002A0463 |
| Current U.S. Class: |
384/484; 152/417; 384/477; 384/544 |
| Intern'l Class: |
F16C 033/78; B60C023/00 |
| Field of Search: |
384/477,484,544,589
152/417
|
References Cited [Referenced By]
U.S. Patent Documents
| 4730656 | Mar., 1988 | Goodell et al.
| |
| 4733707 | Mar., 1988 | Goodell et al.
| |
| 4844138 | Jul., 1989 | Kokubu.
| |
| 4932451 | Jun., 1990 | Williams et al.
| |
| 5080157 | Jan., 1992 | Oerter.
| |
| 5503480 | Apr., 1996 | Caillaut et al.
| |
| 6199611 | Mar., 2001 | Wernick.
| |
| Foreign Patent Documents |
| 3738529 | Oct., 1988 | DE.
| |
| 656 267 | Jan., 1996 | EP.
| |
| 713 021 | May., 1996 | EP.
| |
| 2714943 | Jul., 1995 | FR.
| |
Primary Examiner: Hannon; Thomas R.
Attorney, Agent or Firm: Merchant & Gould P.C.
Claims
1. A bearing unit for a wheel hub of a vehicle equipped with a system for supplying
pressurized air to a tyre through the hub of the wheel, of the type in which the
bearing unit comprises:
a first stationary annular element (
1,
16) with at least a first
inner air passage (
6),
at least a second rotatable annular element (
2a,
2b;
17) with at least a second essentially radial inner air passage (
7,
71,
72),
an intermediate annular chamber (
13) between the first (
1,
16)
and the second (
2a,
2b;
17) annular elements;
characterised in that said at least one second passage (
7,
71,
72)
has a surface (
71d,
72d) inclined forwardly with respect
to a direction of rotation (A, B) so as to favour the air flow from the intermediate
annular chamber (
13) through the second passage (
7,
71,
72).
2. A bearing unit according to claim 1, wherein said at least one second passage
(
7,
71,
72) has a cross-section progressively decreasing in
a radial direction away from the first stationary annular element and that said
second passage is inclined forwardly with respect to a direction of rotation (A, B).
3. A bearing unit according to claim 2, wherein:
the first annular element (
1,
16) is radially outer,
the second annular element (
2a,
2b;
17) is
radially inner and adapted for being mounted fast for rotation to a wheel hub,
and
said at least one second inner passage (
7,
71,
72) has a
cross-section progressively decreasing from the outside towards the inside.
4. A bearing unit according to claim 1, wherein:
the first annular element (
1,
16) is radially outer;
the second annular element (
2a,
2b;
17) is
radially inner and is adapted for being mounted fast for rotation with a wheel
hub.
5. A bearing unit according to claim 4, wherein at least one of said second inner
passages (
7,
71,
72) is defined by at least a recess (
71a,
72a) formed in at least one of two facing surfaces (
15) of
two adjacent radially inner half-races (
2a,
2b) of
the bearing unit.
6. A bearing unit according to claim 5, wherein at least one of said second inner
passages (
7,
71,
72) is defined by a pair of complementary
recesses formed in respective facing surfaces (
14) of two adjacent radially
inner half-races (
2a,
2b) of the bearing unit.
7. A bearing unit according to claim 6, wherein the complementary recesses formed
in the two inner half-races (
2a,
2b) are specular.
8. A bearing unit according to claim 1, comprising a plurality of said inclined
surfaces (
71d,
72d), at least one (
71d)
of which is inclined forwardly with respect to a first direction of rotation (A),
and at least another (
72d) of which is inclined forwardly with respect
to a second direction of rotation (B) opposite to the first direction (A).
9. A bearing unit according to claim 1, wherein said inclined surface (
71d,
72d) is curved and concave with a concavity facing the same direction
of rotation towards which said surface is forwardly inclined.
10. A bearing unit according to claim 9, wherein in at least one of said second
passages (
7,
71,
72) the inclined and concave surface (
71d,
72d) is facing an opposite curved and convex surface (
71c,
72c).
11. A bearing unit according to claim 1, wherein said at least one inclined surface
(
71d,
72d) is formed by an air conveyor rotor (
14)
of essentially annular shape fast for rotation with the second rotatable annular
element (
2a,
2b;
17).
12. A bearing unit according to claim 11, wherein the air conveyor rotor (
14),
forms lateral surfaces (
16) at the sides of each inclined surface (
71d,
72d), whereby the rotor has radially oriented air inlets (
20a,
20b).
13. A bearing unit according to claim 12, wherein the air inlets (
20a,
20b) are facing alternate opposite tangential directions along the
perimeter of the rotor.
14. A bearing unit according to claim 11, wherein the air conveyor rotor (
14)
has a peripheral undulated or multi-lobed shape, where in each lobe (
21)
there is formed a pair of said surfaces (
71d,
72d)
inclined forwardly with respect to opposite directions of rotations and curved
with concavities facing opposite directions of rotation (A, B).
15. A bearing unit according to claim 14, wherein the pairs of inclined surfaces
(
71d,
72d) are part of respective pairs of passages
(
71,
72), where the two passages of each pair open onto the peripheral
surface of the rotor forming air inlets (
20a,
20b)
facing opposite directions of rotation (A, B).
16. A bearing unit according to claim 15, wherein the passages of each pair of
passages (
71,
72) converge so as to face and communicate with one
of the passages (
7) in the second rotatable annular element.
17. A bearing unit according to claim 1, wherein the radially inner annular element
is an annular element (
21) separate from the rotatable race (
2b)
of the bearing unit and is adapted for being mounted adjacent and fast for rotation
to said rotatable race.
Description
The present invention refers to a bearing unit for the hub of a vehicle wheel
equipped with an on-board tyre inflating system.
There are known bearing units for a vehicle wheel hub provided with special
vents and sealing devices for blowing into the tyre air pressurized by a source
of pressurized air mounted on board of the vehicle. Hub-bearing unit of this kind,
known for example from EP-713 021, EP-656 267, U.S. Pat. No. 5,503,480, DE-37 38
529, FR-2 714 943, allow to adjust and/or monitor the air pressure in the tyres.
The cited documents disclose bearing units for the hub of a vehicle wheel comprising
a non-rotating outer race housed in a cylindrical seat of the suspension standard
and an inner race (usually a pair of half-races located side by side) fast for
rotation with the hub. The air coming from a pressurized air source mounted on
board of the vehicle is blown through special conduits obtained in the suspension
standard. Radial passages are formed in the outer and inner races of the bearing
for conveying air through the outer race into an intermediate annular chamber between
the races and then through the inner race or half-races towards the centre of the
bearing. From here, the air is conveyed through other conduits to the wheel rim
and then the tyre.
It has been noted that, at high speed of rotation, the pressurized air encounters
difficulties in passing through the bearing, particularly in passing from the intermediate
chamber through the rotating part of the bearing.
Accordingly, the object of the present invention is to improve the air
flow through the bearing, particularly through its rotating part.
This and other objects and advantages, that will be better understood herein
after, are accomplished according to the invention by a bearing unit as defined
in the appended claims.
The constructional and functional features of a few preferred but not limiting
embodiments of a bearing unit according to the present invention will now be described,
reference being made to the accompanying drawings, in which:
FIG. 1 is a schematic cross sectional view of a bearing unit according to the
invention for the hub of the wheel of a vehicle equipped with a tyre inflating system;
FIG. 2 is a schematic radial cross-sectional view along the line II—II
of FIG. 1;
FIG. 3 is a partial perspective view of one of the two inner half-races of the
bearing unit of FIG. 1;
FIG. 4 is a schematic axial cross-sectional view of another embodiment of bearing
unit according to the invention;
FIG. 5 is a schematic axial cross-sectional view, similar of that of FIG. 1,
of a bearing unit according to a further embodiment of the invention, provided
in this example with an air conveyor rotor;
FIG. 6 is a schematic view in radial cross-section taken along the line VI—VI
of FIG. 5;
FIG. 7 is a partial perspective view of some of the components of FIG. 6;
FIG. 8 is a schematic view in radial cross-section of a rotating half-race of
the bearing with an air conveyor rotor alternative to that of FIGS. 6 and 7;
FIG. 9 is a partial perspective view of the components of FIG. 8; and
FIG. 10 is a schematic axial cross-sectional view of a further and still different
embodiment of a bearing unit according to the invention.
With reference initially to FIG. 1, a bearing unit comprises a radially outer
stationary race
1, a radially inner rotatable race
2 formed by two
axially adjacent half-races
2a,
2b, and two sets of
rolling balls
3 interposed between the outer race
1 and the inner
races
2a,
2b. In a radial plane located between the
two sets of balls
3 there are provided one or more radial passages
6
are formed through the bearing outer race
1 and one or more essentially
radial passages
7 obtained through the bearing inner race
2, described
in detail in the following.
In the annular space defined by the outer race
1, the inner half-races
2a,
2b and the two sets of balls
3 there is
mounted a sealing device
8 of known kind, that allows the pressurized air
to pass through the outer
6 and inner
7 passages of the bearing.
The sealing device is constituted by two annular sealing elements
9 facing
one another axially and symmetrically with respect to the radial plane in which
the passages
6,
7 of the bearing unit lie. Each sealing element
9
comprises a metal reinforcement
10 on which there is moulded a flexible
material, such as an elastomer, forming sealing lips
11 in sliding contact
with contacts surfaces
12 of the inner half-races
2a,
2b.
The two sealing elements
9 so arranged delimit an intermediate annular
chamber
13. Pressurized air coming from a source of pressurized air mounted
on board of the vehicle, which may be part of an automatic system or a system controlled
by the driver, passes through special ducts (not shown) formed in the suspension
standard of the wheel where the bearing is housed, passes through the passage
6,
into the intermediate chamber
13, through the passages
7, and from
here is conveyed through other conduits (not shown) to the wheel rim and then the tyre.
As shown in FIG. 2, the inner passages
7 have a cross section progressively
decreasing from the outside to the inside and are inclined forwardly with respect
to the direction of rotation. Owing to this arrangement, when the inner half-races
rotate fast with the hub, the inner passages
7 create a vacuum in the intermediate
annular chamber
13 that favours the air flow through the rotating part of
the bearing.
In the embodiment schematically illustrated in FIG. 2, the inner passages
7
comprise both inner passages
71 inclined forwardly with respect to the direction
of rotation indicated by arrow A, and inner passages
72 inclined forwardly
with respect to the opposite direction of rotation, indicated by the arrow B. A
hub unit of this kind has the further advantage that it can be mounted indifferently
on a wheel on the left or right side of the vehicle. In one case, the vacuum in
chamber
13 will be provoked by the inner passages
71, and in the
other case by the passages
72.
Preferably, the inner passages
7 are defined by the coupling of
complementary recesses formed, according to a specular symmetry, on facing surfaces
of the two inner half-races
2a,
2b. As shown in FIG.
3, the bearing half-race
2a has, on its radial side
15 facing
the adjacent half-race
2b, a plurality of essential radial recesses
71a,
72a. When the two half-races are placed side by
side, these recesses define with symmetrical recesses of the half-race
2b
the above described inner passages
71 and
72.
For a better introduction of the air in the passages
7, the passages
71,
72 each have a surface
71d,
72d, here defined
"rear" or "trailing" with reference to the direction of rotation, of concave shape
with the concavity facing one of the two possible directions of rotation. To reduce
turbulence, each passage
71,
72 has a respective surface
71c,
72c, here defined "leading" with reference to the direction of rotation,
of convex shape with the convexity facing one of the two possible directions of rotation.
FIG. 4 shows another embodiment of the invention, wherein the air passages are
not formed through the bearing races
1,
2a and
2b,
but in annular elements
16,
17 adapted for mounting on one side of
the bearing races. Annular elements similar to those here indicated
16,
17, but with radial straight passages of constant cross-section are described
and shown in another Italian patent application to the same applicant, to which
reference is made, filed on Mar. 6, 2002 under filing number TO2002A000189 and
not yet available to the public at the filing date of the present patent application.
Referring to FIG. 4, where parts equal or corresponding to those already
described with reference to FIGS. 1 to
3 are designated with like reference
numbers, the bearing unit comprises a stationary outer annular element
16
fixed on one side of the outer race
1 and an inner annular element
17
adapted for being mounted fast for rotation to the hub (not shown) on one side
of the inner half-race
2b. An inner passage formed through the outer
annular element
16 is indicated
6.
Formed in the inner annular element
17 are one or more inner passages
7 having a progressively decreasing cross-section from the outside to the
inside and inclined forwardly with respect to the direction of rotation. The radial
cross-section (not shown) of the internal annular element
17 is similar
to that of FIG. 2, of which reference is made. Also in this embodiment of the invention
each of the inner passages
7 has a trailing surface with reference to one
of the two possible direction of rotation, inclined forwardly with respect to the
direction of rotation being considered and preferably curved with a concavity facing
said direction of rotation. Between the annular elements
16 and
17
there is mounted a sealing device
8 defining an intermediate annular chamber
13 communicating with the passages
6 and
7 to allow the passage
of pressurized air in a manner similar to what described with reference to FIGS.
1 to
3.
Referring now to FIGS. 5,
6 and
7, according to another embodiment
of the invention, fitted on the rotating half-races
2a,
2b
is an air conveyor rotor
14 of annular shape with a plurality of passages
71,
72 each having a surface
71d,
72d radially
protruding in the intermediate annular chamber
13. Each surface
71d,
72d is inclined forwardly with respect to one of the two possible
directions of rotations. The surfaces
71d,
72d are
each disposed in proximity of one of the passages
7 formed in the rotating
half-races
2a,
2b and extend from an edge of the passage
(here defined "trailing" edge with reference to a direction of rotation) towards
the outside and forwardly in such a direction of rotation. Owing to this arrangement,
when the inner half-races rotate fast with the hub, the inclined surfaces capture
the air in the intermediate chamber
13 and convey it into the passageways
7 formed through the rotating part of the bearing.
Also in this embodiment, as shown schematically in FIG. 6 and 7, there are provided
both surface
71d inclined forwardly with respect to the direction
of rotation indicated by arrow A, and surfaces
72d inclined forwardly
with respect to the opposite direction of rotation, indicated by arrow B. A bearing
unit fitted with an air conveyor rotor of this kind has the further advantage that
it can be indifferently mounted to a wheel on the left or right side of a vehicle.
In one case, when the direction of rotation is that indicated by arrow A, the air
will be captured in chamber
13 by the surfaces
71d, and, in
the other case, by the surfaces
72d. To improve the capturing of
air to be conveyed through the bearing, the inclined surfaces
71d,
72d are preferably curved with a concavity facing one of the two
possible directions of rotations.
In the example of FIGS. 6 and 7, the air conveyor rotor
14 forms a pair
of side surfaces
18 located at the sides of each inclined surface
71d,
72d, whereby the rotor has two sets of air inlets
20a,
20b alternately facing opposite tangential directions along the perimeter
of the rotor.
In the example of FIGS. 8 and 9, the rotor
14 has a peripheral undulated
or multi-lobed shape. At each lobe
21 there is formed a pair of surfaces
71d,
72d inclined forwardly with respect to opposite
directions of rotations and curved with concavities facing opposite directions.
The pairs of inclined surfaces in each lobe are part of a respective pair of passages
71,
72 that converge so as to face and communicate with one of the
passages
7 in the rotating race of the bearing. Each of the passages
71,
72 a cross-section progressively decreasing from the outside to the inside
and is inclined forwardly with respect to a direction of rotation opposite to that
of the other passage of the pair. The passages
71,
72 open on the
peripheral surface of the rotor forming air inlets
20a,
20b
facing opposite directions (FIG.
9).
Upon rotating with the rotatable part of the bearing, the rotor
14 captures
air from the intermediate chamber
13 through the air inlets
20a
(or
20b according to the direction of rotation). The inclined
surfaces
71d (or
72d) convey air into the passages
7 formed through the rotating part of the bearing. The progressively decreasing
cross-section of the passages
71,
72 is advantageous in that it generates
a vacuum in the intermediate annular chamber
13 that favours the air flow
through the rotating part of the bearing.
Similarly to what is shown in FIG. 2, also in the example of FIGS. 8 and
9 in each passage
71,
72 the surface
71c,
72c,
here defined "leading" with reference to the direction of rotation being considered
has a convex shape to reduce turbulence. For a better introduction of air in the
passages
7, the "trailing" surface
71d,
72d,
which serves to capture the air, is instead curved with a concavity facing the
direction of rotation. It is to be noted that in the examples of FIGS. 6 to
9,
the passages
7 formed through the rotating part of the bearing may be radial
and straight. Still according to the invention, it is also possible to associate
an air conveyor rotor of the type indicated
14 with a bearing unit with
inclined inner passages as shown in FIGS. 2 to
4.
In FIG. 10 there is shown another embodiment of the invention, in which the air
passages are not formed through the bearing races
1,
2a and
2b, but in a device comprised of annular elements
16,
17
adapted for being mounted to a side of the bearing races, similarly to what is
shown in FIG.
4. The bearing unit of FIG. 10 includes a stationary outer
annular element
16 fixed to a side of the outer race
1 and an inner
annular element
17 adapted for being mounted fast for rotation to the hub
(not shown) on one side of the inner half-race
2b. An inner passage
formed through the outer annular element
16 is indicated
6. Formed
in the inner annular element
17 are one or more inner radial passages
7.
Between the annular element
16 and
17 there is mounted a sealing
device
8 defining an intermediate annular chamber
13 communicating
with the passages
6 and
7 to allow the passage of pressurized air
through the annular elements
16 and
17.
An air conveyor rotor
14 is fitted onto the inner rotatable annular element
17 in a manner similar to what has already been described in FIGS. 5 to
9. Also in this embodiment of the invention, when the inner annular element
is rotating, the inclined surfaces of the rotor
14 capture air from the
intermediate chamber
13 and convey it into passages
7 formed through
the rotating annular element.
It is to be understood that the invention is not limited to the embodiments here
described and illustrated, which are to be considered as examples of a bearing
unit according to the invention. The invention is likely to undergo modifications
as to shape and location of parts, constructional and functional details, and materials
employed. For example, the bearing units here shown are units of the so-called
first generation. However, reference to this possible field of use should not in
any way be interpreted as limiting the scope of the patent, as the invention is
equally applicable to bearing units of the so-called second or third generation
with flanges races.
In addition, those skilled in the art will recognize that the invention is equally
applicable to bearing units in which the outer race is rotatable and the inner
race is stationary.
Finally, the section of the second passages
7,
71,
72
may take any shape, for example polygonal, (as shown in FIG. 3) or curved.
*
