U.S. patent application number 10/627080 was filed with the patent office on 2004-03-25 for axle boot.
This patent application is currently assigned to Carl Freudenberg KG. Invention is credited to Kammann, Andreas, Wolf, Joachim.
Application Number | 20040056434 10/627080 |
Document ID | / |
Family ID | 30001513 |
Filed Date | 2004-03-25 |
United States Patent
Application |
20040056434 |
Kind Code |
A1 |
Wolf, Joachim ; et
al. |
March 25, 2004 |
Axle boot
Abstract
An axle boot for joint sealing, in particular on the drive train
of motor vehicles, includes a substantially axisymmetric bellows,
which is designed as a single piece with a connecting collar. The
connecting collar has a plurality of indentations projecting
towards the inside that are adapted to radial recesses in the
external contour of the joint housing. To the outside of the
connecting collar are attached compensating pieces that complete
the external contour, forming a cylindrical circumferential surface
on which a clamp is located.
Inventors: |
Wolf, Joachim; (Weinheim,
DE) ; Kammann, Andreas; (Heidelberg, DE) |
Correspondence
Address: |
DAVIDSON, DAVIDSON & KAPPEL, LLC
485 SEVENTH AVENUE, 14TH FLOOR
NEW YORK
NY
10018
US
|
Assignee: |
Carl Freudenberg KG
Weinheim
DE
|
Family ID: |
30001513 |
Appl. No.: |
10/627080 |
Filed: |
July 25, 2003 |
Current U.S.
Class: |
277/634 |
Current CPC
Class: |
F16D 3/845 20130101 |
Class at
Publication: |
277/634 |
International
Class: |
F16J 015/52 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 26, 2002 |
DE |
102 34 284.9-12 |
Aug 21, 2002 |
DE |
102 39 169.6-12 |
Claims
What is claimed is:
1. An axle boot for joint sealing, comprising: a joint housing
including an external contour having a plurality of radial
recesses; a substantially axisymmetric bellows including an
integral connecting collar formed as a single piece, the connecting
collar including a plurality of indentations projecting radially
inward each indentation adapted one of the radial recesses; and a
plurality of compensating pieces attached to an outer surface of
the connecting collar so as to form a cylindrical outer
circumferential surface.
2. The axle boot as recited in claim 1, wherein the axle boot is
for sealing a joint on a drive train of a motor vehicle.
3. The axle boot as recited in claim 1, wherein a circumferential
length of each of the plurality of compensating pieces corresponds
approximately to a circumferential length of an associated radial
recess.
4. The axle boot as recited in claim 1, wherein the plurality of
compensating pieces are connected to each other to form a
single-piece component extending around an entire circumference of
the connecting collar.
5. The axle boot as recited in claim 4, wherein the single-piece
component includes a plurality of ring sections for connecting
adjacent ones of the plurality of connecting pieces, at least one
of the ring sections being elastically deformable in the a
circumferential direction.
6. The axle boot as recited in claim 5, wherein at least one of the
ring sections includes a meander shape.
7. The axle boot as recited in claim 1, further comprising a
circumferential clamp for the connecting collar, the compensating
pieces connected to the circumferential clamp.
8. The axle boot as recited in claim 7, wherein the compensating
pieces are integrated with the clamp as an integrated
multi-component unit.
9. The axle boot as recited in claim 1, wherein each compensating
piece includes a more than one material component, each of the
material components having a different hardness.
10. The axle boot as recited in claim 1, wherein each of the
compensating pieces is a fluid-filled hollow body having flexible
walls.
11. The axle boot as recited in claim 1, wherein the bellows is
made of a thermoplastic copolyester (TPE).
Description
[0001] Priority is claimed to German patent application no. 102 34
2894.9-12, filed on Jul. 26, 2002 and to German patent application
no. 102 39 169.6-12, filed on Aug. 21, 2002. The subject matter of
both of the aforesaid German patent applications is hereby
incorporated by reference herein.
BACKGROUND
[0002] The present invention relates to an axle boot for joint
sealing, in particular on the drive train of motor vehicles, that
includes a substantially axisymmetric bellows, which is designed as
a single piece with a connecting collar, and compensating pieces
attached to and distributed over the connecting collar for the
purpose of adapting to an external contour of a joint housing, a
contour that includes a plurality of radial recesses.
[0003] Axle boots of this type are typically used to seal off
joints in the drive train of motor vehicles, joints whose joint
housing has an external contour that includes a plurality of radial
recesses. Since three radial recesses are usually provided on the
circumference, the result is a three-lobe external contour that is
also described as trilobe-shaped, which is at the same time the
interface to the axle boot, which is usually fastened by clamps.
The sealing of the joint area is necessary in order to keep dirt
and moisture away from the joint and to preserve the grease filling
in the joint.
[0004] For the purpose of adapting the connecting collar of the
bellows on to the non-axisymmetric external contour of the joint
housing, it is known in the case of axle boots manufactured from
elastomers by the injection-molding method to provide enlargements
in the connecting collar that act as compensating pieces and
compensate for the radius differences of the external contour of
the joint housing so that a circular clamp can be used for clamping
purposes.
[0005] In this case, pronounced undercuts are formed on the inside
at the transition from the connecting collar to the bellows. The
elastomer material that is used makes easy demolding possible, in
spite of these pronounced undercuts, since it has sufficient
reversible extensibility. This manufacturing method, however, is no
longer possible if the axle boot is to be manufactured from a
thermoplastic copolyester (TPE). A molding having such pronounced
undercuts would be destroyed during demolding since it does not
withstand the necessary extensions. In addition, the formation of
great wall thickness differences in thermoplastic moldings requires
long cooling times in the mold and results in sink marks or the
formation of voids.
[0006] In order to avoid these difficulties, the connecting collar
for a known axle boot (European Patent Application EP 0 924 450 A2)
is cylindrical in design. An annular insert that is surrounded by
the connecting collar is provided for the purpose of adapting to
the joint housing's external contour, which is provided with radial
recesses. This insert has a plurality of projections that protrude
into the inside and fit into the radial recesses of the joint
housing. The axle boot can be manufactured relatively easily
because the connecting collar, in particular, has a constant wall
thickness and no undercuts are formed that would be a hindrance
during demolding. Disadvantageous, however, is the fact that the
bellows or at least its connecting collar must be reheated in a
second manufacturing step in order to create the bond with the
insert. This has a disadvantageous effect on strength and geometry
due to molecule rearrangement. In addition, there is another joint
between the connecting collar and the insert that has no useful
function but must also be designed so that it seals.
[0007] That type of joint is avoided in an axle boot described in
European Patent Application EP 0 915 264 A2, through the formation,
in a single piece, of compensating pieces on the inside of the
connecting collar that fit into the radial recesses in the joint
housing. The known axle boot is manufactured in a combined
injection blow molding process that makes an automated
manufacturing run possible. The compensating pieces must be
reinforced by radial webs in order to transfer the clamping force
for the purpose of connecting the axle boot to the joint housing.
The necessary optimization of wall thickness distribution makes any
changes in the compensating pieces complicated and expensive
because the injection-molding mold has to be changed for this
purpose.
SUMMARY OF THE INVENTION
[0008] An object of the present invention is to provide an axle
boot of the kind cited at the beginning of this document such that
it may be manufactured from TPE, taking into account the
material-specific boundary conditions. An additional or alternative
object is to avoid the technical difficulties of the known
designs.
[0009] The present invention provides an axle boot for joint
sealing, in particular on the drive train of motor vehicles, that
includes a substantially axisymmetric bellows designed as a single
piece with a connecting collar, and comprising compensating pieces
attached to and distributed on the connecting collar for the
purpose of adapting to an external contour of a joint housing, a
contour that includes a plurality of radial recesses. The
connecting collar (5) has a plurality of indentations (5a)
projecting towards the inside that are adapted to the radial
recesses (2) of the external contour of the joint housing (1), and
the compensating pieces (6, 6') are attached to the outside of the
connecting collar (5) and complete its outside contour, forming a
cylindrical circumferential surface.
[0010] Between the axle boot and the joint housing there is only
one single joint that needs to be sealed. Since the contact
surfaces between the connecting collar and the compensating pieces
lie on the outside, no sealing is required there.
[0011] The connecting collar that forms the interface between the
axle boot and the joint housing is formed immediately during the
first manufacturing step. Because of the trilobe-shaped contour of
the connecting collar, an unnecessary additional sealing surface is
avoided. The previous molds for axle boots made of thermoplastic
copolyester in which the connecting collar has a radially symmetric
design may be used, after a slight change, for manufacturing the
axle boots according to the present invention, which have a
non-axisymmetric connecting collar. As was already the case with
the conventional method, wall thickness differences may be
minimized by using the available machine technology.
[0012] Nevertheless, the use of a circular clamp is possible, as
before, because the spacings between the connecting collar and the
outside contour are bridged by the compensating pieces attached to
the outside. The compensating pieces transfer the clamping force
from the clamp to the connecting collar and thus to the joint being
sealed. A tight bond between the compensating pieces and the
connecting collar is not required.
[0013] In accordance with one embodiment of the present invention,
it is provided that the circumferential length of each compensating
piece corresponds approximately to the circumferential length of
the associated radial recess. The compensating pieces include, in
this case, a plurality of components that are separated from one
another and located at a circumferential distance from one
another.
[0014] In order to reduce the assembly expenditure in automotive
manufacturing, all compensating pieces may be designed such that
they are connected in the form of a single-piece component
extending around the entire circumference of the connecting collar.
This also brings about a reduction in diameter.
[0015] Preferentially, the compensating pieces may be connected to
a circumferential clamp for the connecting collar. The compensating
pieces may also be designed together with the clamp as an
integrated multi-component unit. All these measures serve
essentially to simplify assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Exemplary embodiments of the invention are explained in
greater detail in the following and are shown in the drawings, in
which:
[0017] FIG. 1 shows a joint housing with an attached axle boot in
three-dimensional representation;
[0018] FIG. 2 shows the axle boot of FIG. 1 along with the
associated compensating pieces in partial cutaway
representation;
[0019] FIG. 3 shows the axle boot of FIGS. 1 and 2 in
three-dimensional representation;
[0020] FIG. 4 shows the axle boot of FIG. 3 with compensating
pieces attached to it;
[0021] FIG. 5 shows the axle boot of FIG. 3 with compensating
pieces that are connected to one another annularly;
[0022] FIG. 6 shows the compensating pieces of FIG. 5 that are
connected to one another annularly; and
[0023] FIG. 7 shows the compensating pieces of FIGS. 5 and 6 that
are connected to one another annularly, whereby the ring sections
that connect the compensating pieces are designed in the shape of a
meander.
DETAILED DESCRIPTION
[0024] FIG. 1 shows a joint housing 1 made of metal for a joint in
the drive train of a motor vehicle. The external contour of joint
housing 1 includes a plurality of radial recesses 2--three of them
in the exemplary embodiment shown in the figure. An axle boot 3
made of a thermoplastic copolyester (TPE) includes an axisymmetric
bellows 4 and is used to seal off the joint in the drive train of
the motor vehicle.
[0025] A connecting collar 5 of axle boot 3 is designed as a single
piece with bellows 4. Connecting collar 5 includes a plurality of
indentations 5a projecting towards the inside that are adapted to
radial recesses 2 in the external contour of joint housing 1.
[0026] A plurality of compensating pieces 6--three in the exemplary
embodiment shown in the figure--are attached to the outside of
connecting collar 5, in each case on the outside of indentations
5a. Compensating pieces 6 complete the external contour of
connecting collar 5, forming a cylindrical circumferential surface
around which a metal or plastic clamp 7 is clamped in order to
press connecting collar 5 against the external surface of joint
housing 1, thereby forming a seal.
[0027] In the exemplary embodiment shown in FIGS. 1 through 4, the
three single compensating pieces 6 are connected to clamp 7 by
rivets 8, for example.
[0028] In a design that differs from that, compensating pieces 6'
in the exemplary embodiment shown in FIGS. 5 and 6 are connected by
ring sections 9 and bending joints 10 to form a single-piece
component (FIG. 6) that extends around the entire circumference of
connecting collar 5.
[0029] In a design that differs from FIG. 6, compensating pieces 6'
in the exemplary embodiment shown in FIG. 7 are connected by ring
sections 9' that are designed in the shape of a meander to form a
single-piece component that extends around the entire circumference
of connecting collar 5. An advantageous feature of this design is
the fact that the compensating pieces that are adjacent to one
another in the circumferential direction are connected by ring
sections that are designed to be elastically yielding in the
circumferential direction. The ring, including compensating pieces
6 and 6' and ring sections 9 and 9', may compensate for the
positive and negative circumferential changes that occur during
assembly, without fracture and with a low required forming
force.
[0030] In a design that differs from the exemplary embodiments
shown in the figures, compensating pieces 6 may also be designed
together with clamp 7 as an integrated multicomponent unit.
[0031] In the exemplary embodiments shown in the figures,
compensating pieces 6 and 6' each include a radial supporting web
11 that is used for transferring the clamping force from clamp 7 to
connecting collar 5. In a different design, a plurality of
supporting webs may also transfer the clamping force in a
lattice-type structure. In addition, the compensating pieces may
also be fluid-filled hollow bodies with flexible walls. It is also
possible to design the compensating pieces as multi-component units
made of material components of different hardnesses in order to
achieve a very homogeneous pressure distribution between connecting
collar 5 and joint housing 1. The possible design of the
compensating pieces in the form of multi-component units made of
material components of different hardnesses serves the same
purpose.
* * * * *