U.S. patent application number 09/943421 was filed with the patent office on 2002-03-28 for heatable steering wheel, and rim and method thereof.
Invention is credited to Bonn, Helmut, Schlett, Egon.
Application Number | 20020036191 09/943421 |
Document ID | / |
Family ID | 7900111 |
Filed Date | 2002-03-28 |
United States Patent
Application |
20020036191 |
Kind Code |
A1 |
Bonn, Helmut ; et
al. |
March 28, 2002 |
Heatable steering wheel, and rim and method thereof
Abstract
A steering wheel includes a rim having a structural core, an
outer casing, and a heating device for heating the outer casing.
The core includes a frame and an insulating layer formed around the
frame. The heating device includes a layer of electrically
conductive plastic surrounding the core, and a pair of electrodes
extending along the length of the conductive layer. The electrodes
extend substantially along the entire peripheral length of the
conductive layer, and the conductive layer encapsulates the
insulating layer and the electrodes. The conductive layer heats the
outer casing, which can be a decorative layer comprised of one or
more wood, leather, film, and lacquer, when current flows through
the electrodes. The electrodes are positioned along the conductive
layer to allow current to uniformly pass along the periphery of the
steering wheel rim into the conductive layer.
Inventors: |
Bonn, Helmut; (Haibach,
DE) ; Schlett, Egon; (Aschaffenburg, DE) |
Correspondence
Address: |
Lyle Kimms
FOLEY & LARDNER
Washington Harbour
3000 K Street, N.W., Suite 500
Washington
DC
20007-5109
US
|
Family ID: |
7900111 |
Appl. No.: |
09/943421 |
Filed: |
August 31, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09943421 |
Aug 31, 2001 |
|
|
|
PCT/DE00/00672 |
Feb 28, 2000 |
|
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Current U.S.
Class: |
219/204 |
Current CPC
Class: |
H05B 3/34 20130101; B62D
1/065 20130101; H05B 2203/013 20130101; H05B 3/00 20130101; H05B
3/146 20130101; H05B 2203/017 20130101 |
Class at
Publication: |
219/204 |
International
Class: |
B60L 001/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 1, 1999 |
DE |
199 10 132.9 |
Claims
We claim:
1. A heatable steering wheel comprising: a steering wheel rim
comprising a steering wheel rim core, an outer casing, and a
heating device for heating the outer casing, wherein the heating
device comprises a layer of electrically conductive plastic
surrounding the core and two electrodes extending along a length of
the conductive layer, and wherein the outer casing surrounds the
conductive layer.
2. A heatable steering wheel according to claim 1, wherein the
electrodes are positioned along substantially the entire length of
the conductive layer to allow current to uniformly pass along the
periphery of the steering wheel rim into the conductive layer.
3. A heatable steering wheel according to claim 1, wherein the
conductive layer is configured as a plastic shell that at least
partially fits around the core.
4. A heatable steering wheel according to claim 3, wherein the
conductive layer completely surrounds the steering wheel core.
5. A heatable steering wheel according to claim 1, wherein the
conductive layer comprises two half shells connected together over
the steering wheel core.
6. A heatable steering wheel according to claim 5, wherein the two
half shells are joined together by ultrasonic or electromagnetic
welding.
7. A heatable steering wheel according to claim 5, wherein at least
one of the half shells include a securing projection for fastening
to the core.
8. A heatable steering wheel according to claim 7, wherein the core
comprise a steering wheel frame and an internal layer completely
surrounding the frame.
9. A heatable steering wheel according to claim 1, wherein the
conductive layer comprises at least two segments.
10. A heatable steering wheel according to claim 9, wherein the
segments are separately heatable.
11. A heatable steering wheel according to claim 9, wherein one of
the segments is heatable.
12. A heatable steering wheel according to claim 1, wherein the
conductive layer is injection molded over the core.
13. A heatable steering wheel according to claim 12, wherein the
injection molded conductive layer encapsulates the electrodes.
14. A heatable steering wheel according to claim 1, wherein the
electrodes are strip conductors extending along the periphery of
the core.
15. A heatable steering wheel according to claim 1, wherein the
electrodes are spaced from each other in the radial direction or
transversely thereof relative to the steering wheel rim.
16. A heatable steering wheel according to claim 1, wherein the
electrodes are substantially spaced apart diametrically opposite
the core.
17. A heatable steering wheel according to claim 1, wherein the
core comprises a steering wheel frame and an internal layer
substantially surrounding the frame.
18. A heatable steering wheel according to claim 17, wherein a
portion of the steering wheel frame comprises one of the
electrodes.
19. A heatable steering wheel according to claim 1, wherein at
least one of the electrodes comprises copper strands.
20. A heatable steering wheel according to claim 1, wherein at
least one of the electrodes comprises a perforated or profiled
metal strip.
21. A heatable steering wheel according to claim 1, further
including spokes and a steering wheel hub, the spokes connecting
the steering wheel rim to the hub, wherein the heating device heats
portions of the spokes.
22. A heatable steering wheel according to claim 1, wherein the
outer casing is a decorative layer comprised of at least one of
wood, leather, film, and lacquer.
23. A heatable steering wheel comprising: a steering wheel rim
comprising a steering wheel rim core and an outer casing, and a
heating device for heating the outer casing, wherein the heating
device comprises resistance plates formed over the core and two
electrodes extending along the plates, and wherein the outer casing
surrounds the plates.
24. A heatable steering wheel rim comprising: a frame; an
insulating layer formed around the frame; a pair of electrodes
extending along a peripheral length of the insulating layer; and an
electrically conductive layer encapsulating the insulating layer
and the electrodes.
25. A heatable steering wheel rim according to claim 24, wherein
the electrodes extend substantially along the entire length of the
conductive layer.
26. A heatable steering wheel rim according to claim 24, further
including an outer casing, the electrically conductive layer
heating the outer casing when current flows through the
electrodes.
27. A method of heating a steering wheel rim having a structural
core, comprising the steps of: placing a pair of electrodes
positioned substantially diametrically opposite the core;
surrounding the electrodes and the core with an electrically
conductive plastic layer, wherein the electrodes extend along the
length of the conductive layer; flowing current through the
electrodes to distribute current to and heat the electrically
conductive plastic layer.
28. A method according to claim 27, wherein the electrodes are
formed to extend substantially along the entire length of the
conductive layer.
Description
[0001] This is a continuation of International Application
PCT/DE00/00672 having an international filing date of Feb. 28,
2000. This international application was not published in English,
but in German, as WO 00/51872.
BACKGROUND
[0002] To make driving more comfortable in winter or in cold
climate, vehicles can include a heatable steering wheel, in
addition to an air heater and a seat heater. Typically, the
steering wheel rim includes a resistance heating element comprised
of a heating wire. A heatable steering wheel is normally offered in
luxury vehicles, which have a plush matching interior, typically
include matching wood and leather. These materials, however, are
not particularly suitable for transmitting heat because wood and
leather are poor heat conductors. Indeed, a wooden steering wheel
rim is generally thick, making it unsuitable for heating.
[0003] In this respect, German patent publication DE 297 12 839
discloses simplifying the production of a heatable steering wheel
by injection molding conductive plastic shells onto its steering
wheel rim. The conductive plastic acts as a resistance heating
element. Wood and leather are used to dress the rim of a luxury
vehicle. Accordingly, this reference still does not solve the
non-uniform heating problem associated with these materials.
Similar heating problems relating to uniformity and heating speed
occur with a steering wheel rim encased with film or lacquer.
[0004] Accordingly, there is a need for a heatable steering wheel
that can heat poor conductive materials used for covering the
steering wheel rim. The present invention addresses this need.
SUMMARY
[0005] The present invention relates to a heatable steering wheel,
a heatable steering wheel rim thereof, and a method of heating a
steering wheel.
[0006] One aspect of the invention is a steering wheel rim, which
can comprise a steering wheel rim core, an outer casing, and a
heating device for heating the outer casing. The other aspect of
the invention is a steering wheel that can include the
above-described steering wheel rim. The steering wheel can include
a steering wheel hub and spokes that connect the steering wheel rim
to the hub. The heating device also can heat portions of the
spokes.
[0007] The core can include a frame, which can be circular, and an
insulating layer formed around the frame. The insulating layer can
completely or substantially encapsulate or surround the frame. The
heating device can include a layer of electrically conductive
plastic surrounding the core, or resistance plates formed over the
core, and a pair of electrodes extending along the length of the
conductive layer or the resistance plate. More specifically, the
electrodes can extend substantially along the entire peripheral
length of the conductive or insulating layer, and the conductive
layer can encapsulate the insulating layer and the electrodes. The
rim can include an outer casing surrounding the conductive layer.
The conductive layer heats the outer casing, which can be a
decorative layer comprised of one or more of wood, leather, film,
and lacquer, when current flows through the electrodes. The
electrodes are positioned along the conductive layer to allow
current to uniformly pass along the periphery of the steering wheel
rim into the conductive layer. The conductive layer can be
configured as a plastic shell that at least partially fits around
the core. The conductive layer also can completely surround the
core. The conductive layer can be comprised of two half shells
connected together over the core. The two half shells can be joined
together by ultrasonic or electromagnetic welding. At least one of
the half shells can include a securing projection for fastening to
the core or the insulating layer. The conductive layer also can be
comprised of at least two segments, which can be separately heated
or only one of which is heatable. The conductive layer can be
injection molded over the core to encapsulate the electrodes and
the core.
[0008] The electrodes can be strip conductors extending along the
periphery of the core. The electrodes can be spaced from each other
in the radial direction or transversely thereof relative to the
steering wheel rim. The electrodes can be substantially spaced
apart diametrically opposite the core. A portion of the steering
wheel frame can comprise one of the electrodes. Moreover, at least
one of the electrodes can be comprised of copper strands or a
perforated or profiled metal strip.
[0009] Another aspect of the present invention is the method of
heating a steering wheel rim having a structural core. The method
can include the steps of placing the pair of electrodes
substantially diametrically opposite the core, surrounding the
electrodes and the core with an electrically conductive plastic
layer, and flowing current through the electrodes to distribute
current to the electrically conductive plastic layer and heat the
same. The electrodes extend along the length of the conductive
layer. The method can include or more features of the steering
wheel described above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1a illustrates a plan view of a heatable steering
wheel, with its central cover removed.
[0011] FIG. 1b illustrates a cross-sectional view taken along line
Ib-Ib of FIG. 1a.
[0012] FIG. 1c illustrates an enlarged cross-sectional view of FIG.
1b, illustrating the details of the steering wheel rim of FIG.
1b.
[0013] FIG. 2a illustrates a plan view of another embodiment of a
heatable steering wheel, with its central cover removed.
[0014] FIG. 2b illustrates a cross-sectional view taken along line
IIb-IIb of FIG. 2a.
[0015] FIG. 2c illustrates an enlarged cross-sectional view of FIG.
2b, illustrating the details of the steering wheel rim of FIG.
2b.
[0016] FIG. 3a illustrates a plan view of yet another embodiment of
a heatable steering wheel, with its central cover removed.
[0017] FIG. 3b illustrates a cross-sectional view taken along line
IIIb-IIIb of FIG. 3a.
[0018] FIG. 3c illustrates an enlarged cross-sectional view of FIG.
3b, illustrating the details of the steering wheel rim of FIG.
3b.
DETAILED DESCRIPTION
[0019] For clarity, the present drawings omit those components not
essential for illustrating the present invention, such as the
center cover located over the steering wheel hub 3.
[0020] In all illustrated embodiments, the steering wheel 1
comprises a steering wheel hub or base 3, a steering wheel rim 2,
and spokes 5 that connect the steering wheel rim 2 to the hub 3,
and a rim heating device. The rim 2 comprises a circular steering
wheel core. The core, which is structural for supporting a load,
can include a frame 4 and an inner layer 9 encasing or enclosing
the frame 4 as illustrated in the drawings, or can be formed of a
monolithic material or a composite material. The frame 4 or the
core itself can be connected to the spoke 5. The rim 2 further
includes layers of materials that surround the core, such as an
outer casing or cover 8, which can be leather, wood, or other
visually appealing material. The frame or the core can be made of
any conventional structural material, such as metal, plastic,
graphite, carbon fiber, etc., of any configuration that provides
the necessary strength.
[0021] FIGS. 1a-1c illustrate a first embodiment of a steering
wheel 1 according to the present invention. Specifically, referring
to FIG. 1c, the steering wheel frame 4 is situated at the center of
the rim 2 as a supporting element and is connected to the hub 3 via
the spokes 5. In this embodiment, the inner layer 9 completely
surrounds or encases the frame 4, which has a substantially
inverted U-shape. The inner layer 9 can be plastic, such as
polyurethane or PUR, which have insulating properties. The rim 2
further includes an intermediate layer or shell 7, which can be
plastic for example, completely surrounding or encasing the inner
layer 9. The outer casing or cover 8, such as leather, surrounds
the intermediate layer 7.
[0022] According to this embodiment, the rim heating device
comprises a pair of electrical conductors 6, 6' of opposite
polarity and the intermediate layer 7, which can be electrically
conductive plastic surrounding the conductors 6, 6'. The conductors
6, 6' can be strip conductors. The conductors 6, 6' can be
positioned diametrically opposite to each other over the inner
layer 9. FIG. 1c illustrates these conductors 6, 6' positioned at
twelve (top) and six (bottom) o'clock and sandwiched between the
inner layer 9 and the intermediate layer 7. The electrically
conductive shell or intermediate layer 7 is thus electrically
connected to the conductors 6, 6', which extend circumferentially
or peripherally U around the rim 2, as illustrated in FIG. 1a. The
conductors or conductor strips 6, 6' can be formed of one or more
metal strands encased in a conductive sheath 12, which can be made
of conductive plastic. This sheath 12 is designed to stabilize the
metal strands, which can be made of copper.
[0023] The conductive plastic shell 7 can be formed to have a
suitable resistance by mixing plastic with conductive material or
particles. For example, polymers filled with carbon fibers, carbon
black or metal particles, for example HOSTAFORM X326 (POM with
carbon fibers) from HOECHST are available for this purpose. The
resistance can be controlled at least with the quantity of the
conductive material used.
[0024] As the conductors 6, 6' extend over the entire circumference
or periphery U of the rim 2, current can flow through the shell 7
over its entire length, which like the conductors 6, 6' extends
along the periphery U of the steering rim 2, from one conductor 6
to the other conductor 6'. Because the conductors 6, 6' extends the
entire length of the shell 7, the shell 7 can uniformly generate
heat to uniformly heat the outer cover 8. The conductors 6, 6' can
be connected to a power source via supply lines 11. FIG. 1a
illustrates a supply line 11 for the upper electrode 6. A supply
line 11 for the lower electrode 6' can be arranged on the lower
side of the steering wheel rim 2, opposite the upper electrode
supply line 11.
[0025] Based on the present configuration, the cover 8 can be
uniformly heated using only a single current connection, via the
supply lines 11, since the current is uniformly distributed around
the periphery U of the shell 7 as the diametrically opposite
conductors 6, 6' extend along the entire length of the shell 7. In
the first embodiment, the upper and lower conductors 6, 6' are
spaced apart from each other substantially perpendicularly with
respect to the radial direction R of the rim 2. The shell 7, which
is the heating element, therefore can have a low resistance, and
the heat output can be targeted by appropriate selection of the
shell thickness and the distance between the conductors 6, 6'.
[0026] The steering wheel 1 according to this embodiment can be
formed by molding or injecting molding the inner layer 9 around the
frame 4. After this step, the conductors 6, 6' can be set, such as
by gluing or adhering onto the inner layer 9. Then, the shell 7 can
be formed by injection molding conductive plastic over the inner
layer 9 and the conductors 6, 6' to completely encase or
encapsulate them. This step also forms electrical contacts between
the conductors 6, 6' and the shell 7. Finally, the casing 8 can
cover shell.
[0027] FIGS. 2a-2c and FIGS. 3a-3c illustrate second and third
embodiments of a steering wheel 1 according to the present
invention. These embodiments include components that are identical
or similar to the ones described with respect to the first
embodiment (FIGS. 1a-1c), identified by the same reference numbers.
The description of identical or similar components previously
described is thus omitted.
[0028] In the second embodiment (FIGS. 2a-2c ), the steering wheel
frame 4 is comprised of a metallic material, which can be used as a
second electrode, as can best been seen from FIGS. 2b and 2c. In
this respect, the frame 4 has a portion that projects through the
inner layer from one side of the steering wheel rim 2 and extends
into the shell 7 so that can be in electrical contact with the
shell 7 along its entire length. In the illustrated embodiment, the
frame has a substantially inverted Y-shape. The vertical leg
portion thereof forms one of the conductors 6, 6'. Otherwise, the
steering rim can be formed in the same manner as described in the
first embodiment.
[0029] FIGS. 3a-3c illustrate the third embodiment of a steering
wheel according to the present invention. This embodiment differs
in two respects from the first and second embodiments. First, in
the third embodiment, the electrically conductive shell 7 is
divided into four discrete segments 7a-7d. These segments can have
different outer casings 8 and also can be independently heated. In
the exemplary embodiment, only segments 7a, 7c, referred to
respectively as a 3 o'clock position and a 9 o'clock position of
the steering wheel, are heated. The other two segments 7b, 7d can
have an insulating plastic instead of a conductive plastic.
Secondly, each of the shell segments 7a, 7c comprises of two half
shells 7', 7", as can be seen on the right-hand side of FIG. 3c.
These half shells 7', 7" are connected in a play-free manner to the
inner layer 9 via a securing projection 10 (for example, by means
of latching elements). Furthermore, the two half shells 7', 7" can
be connected to each other by electromagnetic welding or ultrasonic
welding, in which case the two strip conductors 6, 6' can act as
heating elements or direction indicators for the welding
process.
[0030] FIG. 3c, on the left-hand side, illustrates the non-heatable
shell segments 7b, 7d. Here, perforated metal strips can replace
the conductors 6, 6' of the heatable shell segments 7a, 7c. The
metal strips further improve the ability to hold the shell halves
7', 7" together.
[0031] In this third exemplary embodiment, the conductors 6, 6' run
spaced apart from each other in the radial direction R of the
steering wheel on the "right-hand side" and "left-hand side" of the
steering wheel rim 2, substantially similar to the first
embodiment, but located at left and right, as opposed to top and
bottom.
[0032] In the third embodiment, the inner insulating layer 9 is
formed around the steering wheel frame 4, such as by injection
molding, as in the first and second embodiments. Thereafter, the
half shells 7', 7" can be injection molded into corresponding
shapes and the conductors 6, 6' are placed into complementary
recesses formed in the half shells. The half shells 7', 7" then can
be positioned around the inner layer 9 and, by means of ultrasound
or an alternating magnetic field, the plastic in the region of the
conductors 6, 6' can be melted to join or fuse the half shells 7,
7' together under pressure. This also creates contact between the
conductors 6, 6' and the half shells 7', 7". The half shells 7', 7"
can be secured to the inner layer 9 via a securing projection 10,
which project into a recess or cavity formed in the inner layer 9.
The casing 8 can be is applied over the shell 7.
[0033] Even when an integral, conductive shell 7 is used as in the
first and second embodiments as a resistance heating element,
heating of the individual regions of the steering wheel rim 2 can
be controlled; for example, by insulating the conductors 6, 6' in
the regions not requiring heating, so that no current conducts into
the shell in those regions.
[0034] According to the present invention, the steering wheel can
have at least one heating element formed by an electrically
conductive plastic element. The heating element can extend along
the periphery of the steering wheel rim. The steering wheel further
includes two electrodes of different polarity. These electrodes
extend along and electrically contact the heating element. The
current can supply over the entire length to the heating element,
which can extend along the entire steering wheel rim. Accordingly,
the entire steering wheel rim or selected portions thereof can be
uniformly heated.
[0035] The resistance of the heating element of the steering wheel
according to the present invention can be reduced in comparison
with a heating element described in German patent publication DE
297 12 839 since the current (in the present invention) flows
around a predetermined portion of the conductive shell, namely
circumferentially about a central longitudinal axis of the rim 2
rather than the entire shell, namely circumferentially about the
central axis of the steering wheel. That is, in the present
invention, the current need not conduct through the entire heating
element from one end to the other (electrodes). In the present
invention, the electrodes 6, 6' provide infinite current paths that
can travel through the shell 7 about its central longitudinal axis
so that they can provide current anywhere along the length of the
rim.
[0036] As the shell can be made of conductive plastic, the heat
output can be set in a targeted manner by variation of the
thickness and conductivity of the shell and the distance between
the electrodes. Since the shell is heated uniformly because of the
corresponding supply of current along the periphery of the steering
wheel, reliable heating of the steering wheel in a manner pleasant
for the occupant is ensured even if a poor heat conductive material
(i.e., decor) is used for the outer casing.
[0037] Since the plastic element can be produced in any desired
shape in a very simple manner by injection molding, the outlay on
the production of the heatable steering wheel is considerably
reduced in comparison with steering wheels having a heating wire.
Coiling heating wire around parts of the steering wheel rim is
eliminated according to the present invention.
[0038] The plastic element can be injection molded directly onto
the steering wheel rim core. The shell can comprise two half shells
joined together or mechanically fastened to the core. The half
shells can be connected to each other by ultrasonic welding or
electromagnetic welding, in which case the electrodes extending
along the shells act as energy-direction indicators or as a heating
element. In this regard, the electrodes can be formed from a
perforated or profiled metal strip to form an optimum interlocking
connection as the liquefied plastic can fill any void and spaces
that are present.
[0039] It is expedient for the shell or the half shells to have at
least one securing point for their securing to the steering wheel
frame or part of the rim profile. This results in a play-free
connection between the shell or the half shells and the steering
wheel frame and/or rim profile. For example, the steering wheel
frame may be provided with recesses in which corresponding
projections on the (half) shells engage.
[0040] The electrodes, which extend together with the plastic
element along the periphery of the steering wheel rim, can be
configured as strip conductors. This enables uniform heating to be
achieved with a small overall resistance of the heating device
(comprising the plastic element plus electrodes). The intention is
for the strip conductors to be in contact with the plastic element
at a predetermined, preferably constant spacing from one another.
An arrangement of the electrodes on opposite sides of the plastic
element designed as a shell (for example, spaced apart at the top
and bottom or in the radical direction of the steering wheel rim)
is particularly expedient. Instead of a second strip conductor, the
steering wheel frame, which conventionally is comprised of, in any
case, a conductive metal, can form the second electrode.
[0041] As an alternative, the use of resistance plates instead of
the plastic elements would also be possible, but the production of
the steering wheel is more complicated in this case and therefore
use of resistance plates is preferable only in special cases.
[0042] The outer casing, which covers the shell, can be made, for
example, from wood, leather, film, and/or lacquer. The casing forms
the decorative surface this is visible. The present invention
allows a greater selection of materials and permits a free design.
Even if different materials are used, local overheating is
eliminated since the heating takes place very uniformly by means of
the longitudinally extending plastic element and the placement of
the electrodes, which allows current flow along its direction of
extent.
[0043] With the solution according to the invention it is, of
course, also possible only to heat individual segments of the
steering wheel rim. For this purpose, it is expedient to divide the
plastic element along the periphery of the steering wheel rim into
segments of which only individual ones are heated. For example, it
is therefore possible to heat the steering wheel only in what is
referred to as the 3 o'clock and the 9 o'clock position, i.e., the
regions in which the driver usually grasps the steering wheel.
Also, individual regions or segments of the heating element can be
heated separately, for example to different degrees.
[0044] Furthermore, it is possible at the same time to at least
partially heat the spokes, via which the steering wheel rim is
connected to a steering wheel hub. This can be achieved by
providing a conductive layer to those parts of the spokes to be
heated and the associated electrodes. In this case, the
electrically conductive plastic elements and also the electrodes
can be formed integrally with the corresponding parts of the
steering wheel rim.
[0045] The disclosures of the parent application, PCT/DE00/00672,
and its priority application, DE 199 10 132.9, in their entirety,
including the drawings, claims, and the specification thereof, are
incorporated herein by reference.
* * * * *