U.S. patent application number 09/956077 was filed with the patent office on 2002-03-21 for heater, heater-equipped steering wheel, and method of manufacturing such steering wheel.
This patent application is currently assigned to NIHON PLAST CO., LTD.. Invention is credited to Akaike, Nobukazu, Harada, Hiromitsu, Ochiai, Mikio, Sugiyama, Toshiyuki.
Application Number | 20020033389 09/956077 |
Document ID | / |
Family ID | 27481633 |
Filed Date | 2002-03-21 |
United States Patent
Application |
20020033389 |
Kind Code |
A1 |
Sugiyama, Toshiyuki ; et
al. |
March 21, 2002 |
HEATER, HEATER-EQUIPPED STEERING WHEEL, AND METHOD OF MANUFACTURING
SUCH STEERING WHEEL
Abstract
A heater for a steering wheel includes a heater main body
arranged on a rim of the steering wheel and formed like a net. The
heater main body comprises a plurality of heater wires for
generating heat upon energization and side edges arranged along
longitudinal edges of the heater main body and fixed at an inner
periphery of the rim.
Inventors: |
Sugiyama, Toshiyuki;
(Shizuoka, JP) ; Ochiai, Mikio; (Shizuoka, JP)
; Akaike, Nobukazu; (Shizuoka, JP) ; Harada,
Hiromitsu; (Shizuoka, JP) |
Correspondence
Address: |
Richard L. Schwaab
FOLEY & LARDNER
Washington Harbour
3000 K Street, N. W., Suite 500
Washington
DC
20007-5109
US
|
Assignee: |
NIHON PLAST CO., LTD.
|
Family ID: |
27481633 |
Appl. No.: |
09/956077 |
Filed: |
September 20, 2001 |
Current U.S.
Class: |
219/204 ;
219/528; 219/548 |
Current CPC
Class: |
H05B 2203/014 20130101;
B62D 1/065 20130101; Y10T 74/20834 20150115; H05B 2203/011
20130101; H05B 2203/007 20130101; H05B 2203/017 20130101; H05B 3/34
20130101 |
Class at
Publication: |
219/204 ;
219/528; 219/548 |
International
Class: |
H05B 003/00; B60L
001/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 21, 2000 |
JP |
2000-287360 |
Sep 22, 2000 |
JP |
2000-289200 |
Sep 25, 2000 |
JP |
2000-291315 |
Sep 29, 2000 |
JP |
2000-301025 |
Claims
What is claimed is:
1. A heater for a steering wheel, comprising: a main body arranged
on a rim of the steering wheel, the main body being formed like a
net comprising a plurality of heater wires for generating heat upon
energization; and side edges arranged along longitudinal edges of
the main body, the side edges being fixed at an inner periphery of
the rim.
2. The heater as claimed in claim 1, further comprising an
elongation restraining device arranged along a circumferential
direction of the rim, the elongation restraining device restraining
longitudinal elongation of the main body.
3. The heater as claimed in claim 2, wherein the elongation
restraining device includes a string.
4. The heater as claimed in claim 2, wherein the elongation
restraining device is arranged along each side edge.
5. The heater as claimed in claim 1, wherein that the heater wires
are inclined with respect to a circumferential direction of the
rim.
6. A steering wheel, comprising: a steering-wheel main body with a
rim; a heater arranged on the rim; and a covering arranged on the
heater, wherein the heater comprises a heater main body formed like
a net, the heater main body comprising a plurality of heater wires
for generating heat upon energization and side edges arranged along
longitudinal edges of the heater main body and fixed to the
covering at an inner periphery of the rim.
7. The steering wheel as claimed in claim 6, further comprising a
feed portion connected to an end of the heater main body, and a
protector disposed on the feed portion and the heater main body in
the vicinity of the feed portion.
8. The steering wheel as claimed in claim 7, wherein the protector
is formed out of a deformable material.
9. The steering wheel as claimed in claim 7, wherein the protector
is disposed in layer between the heater and the covering.
10. The steering wheel as claimed in claim 7, wherein the protector
is integrally formed with the covering.
11. The steering wheel as claimed in claim 8, wherein the
deformable material includes cloth, leather, and resin.
12. The steering wheel as claimed in claim 6, further comprising a
heat transfer device arranged between the rim and the covering,
wherein the heat transfer device extends to a position facing a
connection of the covering, and wherein the heat transfer device
has both sides superimposed on the heater main body through the
connection.
13. The steering wheel as claimed in claim 12, wherein the heat
transfer device is greater in heat conductivity than the
covering.
14. The steering wheel as claimed in claim 12, wherein the heat
transfer device comprises a metal sheet.
15. The steering wheel as claimed in claim 6, further comprising a
temperature control device mounted to the steering-wheel main
body.
16. A method of manufacturing a heater-equipped steering wheel,
comprising: placing a heater on a covering of the steering wheel at
an inner periphery and along longitudinal edges of the covering;
connecting ends of the covering to form a tube-like member;
engaging the tube-like member with a rim of the steering wheel at
an outer periphery of the rim; and connecting longitudinal edges of
the tube-like member along the inner periphery of the rim.
17. The method as claimed in claim 16, wherein the heater comprises
a heater main body formed like a net, the heater main body
comprising a plurality of heater wires for generating heat upon
energization and side edges arranged along longitudinal edges of
the heater main body and fixed to the covering at the inner
periphery of the rim.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to heaters for heating
steering wheels for vehicles, heater-equipped steering wheels, and
a method of manufacturing such steering wheels.
[0002] When using the steering wheels for vehicles in cold
conditions such as the outdoors in winter, it is desirable for
comfortable steering after vehicle start to quickly heat a
steering-wheel rim up to a temperature suitable for driver's
holding operation.
[0003] One solution is to heat the steering-wheel rim by means of
engine coolant or hot air out of an air-conditioning box. However,
for cooled vehicles in cold conditions such as the outdoors in
winter, this solution needs sufficient warming-up of the vehicles,
leading to difficulty of quick heating of the rim.
[0004] Another solution is to arrange in a grip portion of the
steering wheel a sheet-like heater to which engine-generated power
is supplied.
[0005] JP-Y2 63-11029 discloses a heater-equipped steering wheel
comprising a steering-wheel main body having a heat insulator at
the outer periphery, a sheet-like heating unit placed on the heat
insulator, and a covering placed on the heating unit. The heating
unit comprises a covered heater wire having a core string and a
heating wire wound thereon, which is disposed zigzag and close on
the inner surface of a heat-equalizing aluminum foil. However, the
zigzag arrangement of the heater wires on the foil needs
complicated operation when visually excellently mounting the
heating unit along the rim of the annular steering wheel having
circular section, leading to difficult enhancement in workability.
In other words, the provision of finished products having excellent
appearance involves an increase in manufacturing cost. Moreover,
the zigzag arrangement often creates protrusion of thick heater
wires on the covering, i.e. so-called outstanding state thereof,
which can be perceived visually and tactilely, resulting in
difficult enhancement in visual quality and operation feel of the
steering wheel.
[0006] JP-A 4-15162 discloses a heatable steering wheel including a
net heating insert obtained by weaving a plurality of thin heating
wires. The heating insert is connected to a covering material by
means of joining or other appropriate means, which is mounted to a
steering-wheel main body. This allows deformation of a heater in
response to the curved surface of the steering-wheel rim in
securing the amount of generated heat per unit area. This structure
is preferable in view of difficulty of creating the so-called
outstanding state of the heater wires. However, mounting the
band-like net heater along the surface of the rim is not easy
operation exactly. Moreover, preforming the net heater to conform
to the shape of the rim involves an increase in manufacturing cost
and a decrease in general versatility. Furthermore, as is not
apparent from the disclosure of JP-A 4-15162, when fixing the net
heater by full application of an adhesive, stress acts
concentratedly on fixed areas to bring easy breaking of the heater
wire. And when having relatively small number of heater wires,
breaking of some heater wires can lower the heater capacity, so
that prudent assembling is needed not to damage the heater wires,
causing lowering of the workability and yield or necessity of
careful inspection, leading to difficult reduction in manufacturing
cost. Particularly, feed portions located at both ends of the
heater wherein an expandable net heating portion and feeders are
connect to terminal plates can concentratedly undergo tensile
stress during assembling, forming a cause of breaking of the heater
wires which can degrade the temperature rise-characteristics.
[0007] As described above, the zigzag arrangement of the heater
wires as disclosed in JP-Y2 63-11029 often creates the outstanding
state of the heater wires on the covering, making difficult the
enhancement in visual quality and operation feel of the steering
wheel. On the other hand, the use of a net heating insert obtained
by weaving thin heating wires as disclosed in JP-A 4-15162 requires
complicated operation of accurately positioning a heater, making
difficult a reduction in manufacturing cost. Moreover, prudent
assembling is needed not to damage the heater wires, making
manufacturing complicated, leading to difficult reduction in
manufacturing cost.
SUMMARY OF THE INVENTION
[0008] It is, therefore, an object of the present invention to
provide heaters for heating steering wheels for vehicles, which
ensure excellent temperature-rise characteristics and easy
assembling with reduced manufacturing cost. Another object of the
present invention is to provide steering wheels equipped with
heater of the present invention. Still another object of the
present invention is to provide a method of manufacturing such
steering wheels.
[0009] The present invention provides generally a heater for a
steering wheel, comprising:
[0010] a main body arranged on a rim of the steering wheel, the
main body being formed like a net comprising a plurality of heater
wires for generating heat upon energization; and
[0011] side edges arranged along longitudinal edges of the main
body, the side edges being fixed at an inner periphery of the
rim.
[0012] One aspect of the present invention is to provide a steering
wheel, comprising:
[0013] a steering-wheel main body with a rim;
[0014] a heater arranged on the rim; and
[0015] a covering arranged on the heater,
[0016] wherein the heater comprises a heater main body formed like
a net comprising a plurality of heater wires for generating heat
upon energization, and side edges arranged along longitudinal edges
of the heater main body and fixed to the covering at an inner
periphery of the rim.
[0017] Another aspect of the present invention is to provide a
method of manufacturing a heater-equipped steering wheel,
comprising:
[0018] placing a heater on a covering of the steering wheel at an
inner periphery and along longitudinal edges of the covering to
form a tube-like member;
[0019] engaging the tube-like member with a rim of the steering
wheel at an outer periphery of the rim; and
[0020] connecting longitudinal edges of the tube-like member along
the inner periphery of the rim.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The other objects and features of the present invention will
become apparent from the following description with reference to
the accompanying drawings, wherein:
[0022] FIG. 1 is a partially cutaway exploded perspective view
showing a steering wheel embodying the present invention;
[0023] FIG. 2 is a perspective view showing a steering-wheel main
body with a heater and a skin mounted;
[0024] FIG. 3 is a view showing the heater;
[0025] FIG. 4 is an enlarged fragmentary view showing part ofthe
heater;
[0026] FIG. 5 is a view similar to FIG. 3, showing the skin with
heater;
[0027] FIG. 6 is a fragmentary perspective view showing a second
embodiment of the present invention;
[0028] FIG. 7 is a cross sectional view showing a rim of the
steering wheel;
[0029] FIG. 8A is a partially cutaway fragmentary front view
showing a third embodiment of the present invention;
[0030] FIG. 8B is a fragmentary sectional view showing the heater
in FIG. 8A;
[0031] FIG. 9A is a view similar to FIG. 8A, showing a fourth
embodiment of the present invention;
[0032] FIG. 9B is a view similar to FIG. 8B, showing the heater in
FIG. 9A;
[0033] FIG. 10 is a view similar to FIG. 9B, showing a fifth
embodiment of the present invention;
[0034] FIG. 11 is a view similar to FIG. 1, showing a sixth
embodiment of the present invention; and
[0035] FIG. 12 is a view similar to FIG. 7, showing the rim in FIG.
11.
DETAILED DESCRIPTION OF THE INVENTION
[0036] Referring to the drawings, a description will be made with
regard to a heater for heating a steering wheel for a vehicle, a
heater-equipped steering wheel, and a method of manufacturing such
steering wheel, which embody the present invention.
[0037] Referring to FIGS. 1-2, a steering wheel 1 for a vehicle
comprises a steering-wheel main body 1 and an airbag device or
module or a pad, not shown, mounted thereto on the side of a driver
or occupant. The steering wheel I is mounted to a steering shaft
that is ordinarily provided with the vehicle in an inclined way.
For the steering wheel 1, refer hereafter the occupant or front
side of the airbag device to as upper side, the steering-shaft or
reverse side to as lower side, the vehicular forward or front-glass
side to as front side, and the vehicular backward or lower rearward
side to as rear side.
[0038] The steering-wheel main body 2 comprises an annular rim 5
called also grip or ring for holding operation, a boss 6 placed
inside the rim 5, and a plurality of (four in the embodiment)
spokes 7 for connecting the rim 5 and the boss 6. Arranged in the
lower part or on the vehicle-body side of the boss 6 is a
substantially cylindrical boss portion 8, to which a boss plate or
hub core 9 is integrally fixed by means of die casting of aluminum
alloy, etc. A core bar 7a of each spoke 7 is integrated with or
fixed to the boss plate 9 by welding or the like to extend
therefrom. A core bar 5a of the rim 5 is fixed to the core bars 7a
of the spokes 7 by welding or the like. An inner covering 10 of
soft polyurethane foam or the like is arranged on all
circumferential surface of the core bar 5a of the rim 5 and the
surface of a rim-side end of each core bar 7a of the spoke 7. Refer
hereafter the side of the rim 5 circumferentially facing the boss 6
to as inner periphery A, and the side opposite to the inner
periphery A to as outer periphery B.
[0039] A resin lower cover 11 called also rear cover or body cover
is attached to the boss 6 of the steering wheel 1 to conceal the
underside of the boss 6. The lower cover 11 has a center opening
11a formed vertically therethrough, a rear opening 11b that opens
to the rear side, and substantially circular side openings 11c that
open to both sides. The steering shaft is arranged through the
center opening 11a, and an electric connection device such as clock
spring, not shown, is disposed therein to electrically connect a
vehicle body and the steering wheel 1. The rear opening 11b and the
side openings 11 serve as work openings. The rear opening 11b is
concealed with a detachable cover or lid 13, and each side opening
11c is concealed with a detachable cover or mask 14. A plurality of
(four in the embodiment) mounting bosses 11d with tapped hole is
formed with the lower cover 11, wherein a screw is engaged with the
mounting boss 1 d through a lower-cover mounting hole 9a of the
boss plate 9 from above, mounting the lower cover 11 to the boss
plate 9.
[0040] Mounting lugs 16 are arranged on both sides of the boss
plate 9 for integration therewith. Each mounting lug 16 includes a
bracket 17 obtained by extending outwardly horizontally and then
being bent upwardly in a slightly outwardly inclined way, and a
bracket slot 18 formed in the transverse center of the bracket 17
to extend longitudinally.
[0041] The airbag device, not shown, has a horn-switch mechanism or
switch device integrally arranged therein, through which an
airbag-device main body is supported. The airbag-device main body
comprises a base plate formed out of a metal plate or the like, an
airbag, a resin cover for concealing the folded airbag, an inflator
for ejecting gas, a retainer for fixing the airbag and the inflator
to the base plate, and a tube-like metal belt for fixing the cover
to the base plate. On the other hand, the horn-switch mechanism
comprises a horn plate or support, a pair of switches, four horn
springs or coil spring or biasing means, three TORX bolts or
coupling means, and a pair of harnesses. The horn-switch mechanism
is mounted to the mounting lugs 16 of the boss plate 9. The push of
the airbag device makes contacts of the horn switches contact with
each other to sound a horn. In the event of vehicle collision or
the like, the inflator quickly jets gas into the folded airbag,
which expands instantaneously to rip and open the cover, obtaining
the airbag deployed in front of an occupant and the horn plate
deformed plastically for occupant restraint.
[0042] A heater 21 is arranged on the surface of an inner covering
10 of the rim 5 of the steering-wheel main body 2, and a skin or
covering member 22 is arranged on the surface of the heater 21.
[0043] Referring to FIG. 1, the heater 21 comprises a heater main
body 25 forming a long band-like net and having a long rectangular
shape as a whole. The heater main body 25 has longitudinal edges
that form side edges 26, and longitudinal ends that form terminals
27a, 27b. The heater main body 25 is obtained by weaving a
plurality of heater wires 28 like a net, wherein each heater wire
28 comprises a core wire generating heat during energization and
having an insulating film on the surface. Specifically, referring
to FIG. 4 wherein one heater wire 28 is shown by thick line for
explanation, each heater wire 28 except heater wires located at a
transverse end is moved rectilinearly by two squares, and hooked to
another heater wire 28 for turning-back. Then, it is moved in the
opposite direction by one square, and hooked to still another
heater wire 28 to be bent roughly at right angles. It is again
moved rectilinearly by two squares to draw a zigzag pattern,
obtaining a weave extending from one terminal 27a to another
terminal 27b.
[0044] As best seen in FIG. 3, attached to each terminal 27a, 27b
of the heater main body 25 is a terminal plate 29 of a copper sheet
to which the core wires of the heater wires 28 are connected in
parallel to constitute a heater with a predetermined capacity.
Preferably, typical heaters for steering wheels have 60-100 W
capacity. One lead wire 31 is connected to each terminal 27a, 27b,
and has a connector 31a mounted at a tip thereof.
[0045] As best seen in FIG. 4, a string 32 of polyester, nylon or
the like is arranged along each side edge 26 to extend
longitudinally. The heater wire 28 located at the transverse end is
hooked thereto for support. As shown in FIG. 3, a double-faced tape
or fixing and joining means 32 is placed at each side edge 26 to
adherer to one side, i.e. the skin 22. The string 32 includes two
white twines, and is smaller in elongation and greater in tensile
strength than the heater main body 25.
[0046] Specifically, referring also to FIG. 5, the heater 21
comprises circumferentially extensible heater main body or heating
portion 25, and elongation restraining means or string 32 for
restraining elongation of the side edges 26 of the heater main body
25. The heater 21 is of a rectangle with the side edges 26 as long
sides, wherein the elongation restraining means 32 are arranged at
the opposite side edges 26. The heater main body 25 is formed like
a net disposed in the bias direction with respect to the
circumferential direction of the rim 5. The rim 5 covered with the
heater main body 25 is covered further with the skin 22, to which
the side edges 26 of the heater 21 are fixed to particular portions
of the skin 22.
[0047] In the illustrative embodiment, the heater wire 28 includes,
for example, a 0.05-0.10 mm diameter copper nickel alloy wire as
core wire, and a polyurethane resin coating as insulting film. A
piece of heater wire 28 has 60 .OMEGA. resistance. As shown in FIG.
4, each heater wire 28 is woven like a net having a rhombic mesh
wherein the length d of each side is 2 mm. A width L of the heater
21 is about 70 mm in natural conditions, between which 30 pieces of
heater wires 28 are arranged in parallel. The heater 21 operates at
12V, and has 72 W capacity.
[0048] As shown in FIG. 5, the skin 22 includes a sheet such as
natural or artificial leather. In the illustrative embodiment, the
skin 22 is formed like roughly a band as a whole by connecting a
plurality of band-like members 41, 42, 43, 44 of natural cowhide to
each other through connections 45. The skin 22 comprises a main
body 47 for covering the rim 5, and extensions 48 extending from
the main body 47 for covering the spokes 7. As best seen in FIG. 1,
the skin 22 has stitch holes 50 formed along the vicinity of edges
49 and throughout the length.
[0049] The operation of mounting the heater 21 to the
steering-wheel main body 21 will be described. Referring to FIG. 5,
the heater 21 having double-side tape 33 placed is stuck to the
inner surface of the roughly band-like skin 22. Then, double-sided
tapes 52 are placed on the inner surface of the heater 21 in the
cross direction and along the connections 45 of the skin 22. The
double-sided tapes 33, 52 placed on the surface of the heater main
body 25 of the heater 21 provide an adhesive effect to both sides
of the heater 21 through meshes of the heater main body 25.
[0050] Then, both ends of the skin 22 having heater main body 25
stuck are joined by sewing or the like to form an annular tube-like
member 55 with the heater 21 located inside as shown in FIG. 1. The
tube-like member 55 has inner diameter that is slightly smaller
than outer diameter of the rim 5 of the steering-wheel main body
2.
[0051] The operation of winding the skin 22 on the rim 5 of the
steering-wheel main body 2 will be described. With the skin 22
pulled and stretched for temporarily enlarging the diameter of the
tube-like member 55, a transverse center 56 of the skin 22, i.e.
the heater 21, as shown by one-dot chain line in FIG. 1 is mounted
along the outer periphery B of the rim 5. In this state, the skin
22 is elastically deformed under tension, and is fitted to the
vicinity of the outer periphery B of the rim 5 without any wrinkle.
During mounting operation, the heater main body 25 of the heater 21
placed on the back or inner surface of the skin 22 is also
stretched. However, the heater main body 25 is formed like a net,
and is not restrained wholly along the skin 22, but free at at
least the outer periphery B, having no concentrated elongation in
particular spots, resulting in no occurrence of breaking of the
heater wires 28. Specifically, when wound on the rim 5 during
mounting operation, the skin 22 and the heater 21 produce
dimensional changes due to respective elongation characteristics.
Since the heater main body 25 is more extensible than the skin 22,
the elongation of the skin 22 does not bring the heater main body
25 to the elongation limit, resulting in no occurrence of breaking
of the heater wires 28 during mounting operation.
[0052] As shown in FIG. 5, since the heater 21 is smaller in width
than the skin 22, the skin 22 has on both sides of the heater 21
blanks 53 on which the heater 21 is not placed. The heater 21 is
placed in a roughly transverse center of the skin 22, wherein the
holes 50 are aligned in a row in the transverse center of each
blank 53, i.e. the blank 53 is divided into two equal parts with
respect to the aligned holes 50 as center line. An adhesive may be
used in place of one or both of the double-sided tapes 33, 52.
[0053] In this state, since no double-sided tape is arranged along
the transverse center of the heater 21, i.e. the transverse center
of the heater 21 is not placed on the skin 22, the heater main body
24 or net of heater wires 21 is not restrained by the skin 22 in
the center of the heater 21, and thus elongates independently of
the skin 22 when stretched.
[0054] The skin 22 elongated at the outer periphery B of the rim 5
is inclined inwardly to wind the rim 5, and then disposed along the
surface of the rim 5 to adhere thereto by means of the double-sided
tapes 33, 52 for temporary fixing.
[0055] Subsequently, the edges 49 of the skin 22 are butted each
other at the inner periphery A of the rim 5, and stitched with a
thread 58 of polyester or the like which passes through the stitch
holes 50 as shown in FIG. 2.
[0056] The lead wires 31 are connected to a harness, not shown, of
the steering-wheel main body 2 through the connector 31 mounted at
the tip.
[0057] Referring to FIG. 1, a thermostat or temperature control
means 23 is mounted to the steering-wheel main body 21. The
thermostat 23 comprises a thermostat main body or temperature
sensor 23a, a lead wire 23b derived from the main body 23a, and a
connector 23c mounted to the lead wire 23b at a tip thereof. The
thermostat main body 23a is accommodated in a concavity, not shown,
formed in the underside of the core bar 7a of the spoke 7 of the
steering-wheel main body 2 to conform to the shape of the main body
23a. The lead wire 23b is drawn to the side of the boss 6 along the
spoke 7, and is connected to a harness, not shown, through the
connector 23c. The thermostat 23 serves to measure the temperature
of the steering wheel 1, base on which the supply of power to the
heater 21 is intermittently carried out to control the
steering-wheel temperature not to be out of a predetermined
temperature range. Moreover, the temperature control means 23 may
include a voltage control circuit, etc. to adjust the amount of
generated heat.
[0058] As described above, the first embodiment shows heater 21 for
covering the annular rim 5 of the vehicular steering wheel 1, and
heater-equipped steering wheel 1. In the first embodiment, the
heater 21 is formed like a net having side edges 26 disposed along
the circumferential direction of the rim 5 and terminals 27a, 27b
each arranged at a termination of the side edges 26 to intersect
them. Moreover, the heater 21 is fixedly mounted to the rim 5 with
the side edges 26 located at the inner periphery of the rim 5, i.e.
it is not fixed on the surface of the rim 5 at the outer periphery
B. Therefore, even when the heater 21 undergoes external force,
this force does not concentratedly act on particular narrow area or
spots of the heater wires 28, but is dispersedly applied on the
heater 21 by its movement on the surface of the rim 5 through the
net structure, preventing breaking of the heater wires 28.
[0059] Moreover, in the structure with the skin 22 for covering the
rim 5 and the heater 21, since the side edges 26 of the heater 21
are fixed to the skin 22 at the position corresponding to the inner
periphery A of the rim 5, i.e. the heater 21 is not restrained by
the skin 22 at the outer periphery B of the rim 5, the skin 22 and
the heater 21 can be elongated without being restrained each other.
Therefore, even when the heater 21 undergoes external force, this
force does not concentratedly act on particular narrow area or
spots of the heater wires 28, but is dispersedly applied on the
heater 21 by its movement on the surface of the rim 5 through the
net structure, preventing breaking of the heater wires 28.
[0060] Specifically, since the skin 22 is elongated by about 20%
during mounting to the rim 5, the center portion of the heater main
body 25 of the heater 21, which is located at the outer periphery B
of the rim 5, undergoes perceptible tension from the skin 22. In
the first embodiment, the center portion of the heater main body 25
is arranged freely movably to protect the heater 21, resulting in
easy mounting operation and reduced manufacturing cost. On the
other hand, the side edges 26 of the heater main body 25 fixed to
another member are not arranged movably, since they are located at
the inner periphery A of the rim 5.
[0061] Moreover, when mounting the heater 21 to the rim 5, the
heater 21 is integrally fixed to the skin 22 to form the annular
tube-like member 55 having inner diameter equal to outer diameter
of the rim 5, which is then mounted to the rim 5. This facilitates
mounting operation including winding of the skin 22 and the heater
21 to the rim 5, leading to less complicated operation and
manufacturing cost with reduced occurrence of breaking of the
heater wires 28 during mounting operation.
[0062] Furthermore, since the net-structure heater main body 25 of
the heater 21 in itself is deformed elastically, there is no need
to fix the heater wires 28 by using an expensive adhesive tape with
elasticity, allowing easy reduction in manufacturing cost compared
with the structure using such adhesive tape.
[0063] Further, the heater 21 comprises circumferentially
extensible net heater main body 25, and strings or elongation
restraining means 32 arranged at the side edges 26 disposed along
the circumferential direction of the heater main body 25 and for
restraining elongation of the side edges 26. The side edges 26
having string 32 can restrain elongation of the heater main body 25
when applying tension to the heater 21, and provide to the heater
21 the characteristics of having a curved shape that facilitates
its mounting to the outer surface of the rim 5. This results in
easy winding of the heater 21 on the rim 5 and difficult occurrence
of wrinkle and displacement, allowing enhancement not only in
workability, but in appearance and quality.
[0064] Specifically, the heater 21 is of a rectangle with the side
edges 26 as long sides, wherein the strings or elongation
restraining means 32 are arranged along the side edges 26. This
structure enables the heater 21 to easily be curved along the
convex surface of the rim 5 with roughly circular section.
Moreover, the presence of the strings 32 at the side edges 26
contributes to stabilization of the shape of the side edges 26,
leading to enhanced workability and quality with restrained
occurrence of extreme density dispersion of the heater wires 28 in
a predetermined area.
[0065] Still further, the elongation restraining means or string 32
include a twine of polyester, nylon or the like, which is soft in
itself, allowing protection of the heater wires 28. Though less
extensible than the heater main body 25, the string 32 can elongate
in some degree, providing easy and neat winding of the heater 21 on
the rim 5. Moreover, the use of the elongation restraining means 32
having greater tensile strength than that of the heater main body
25 allows substantial construction of the edges of the heater
21.
[0066] Furthermore, the heater 21 is constructed such that the
meshes of the heater wires 28 of the heater main body 25 are
inclined with respect to the circumferential direction, i.e. they
are disposed in the bias direction. Therefore, when mounting the
heater 21 to the rim 5, the heater main body 25 can smoothly be
elongated without providing tension to one or both of the radial
direction and the longitudinal direction of the heater wires 28.
This facilitates winding of the heater 21 on the rim 5 without any
uneven arrangement of the heater wires 28, preventing breaking
thereof. Moreover, this increases a difference in elongation
between the heater main body 25 and the string or elongation
restraining means 32, providing easy curvature of the heater
21.
[0067] Further, the rim 5 is covered with the heater 21, which is
in turn covered with the skin 22, allowing protection of the heater
21. Moreover, heating of the skin 22 through heat generated by the
heater 21 can provide more uniform surface temperature thereof.
Moreover, concealing of the heater 21 allows achievement of the
same appearance as that of typical steering wheels with heater 21
that is not enhanced in design particularly.
[0068] Still further, fixing of the edges 26 of the heater 21 to
the skin 22 allows easy and accurate positioning of the heater 21
with respect to the skin 22, and restrained elongation of the skin
22 by means of the string or elongation restraining means 32. Then,
mounting of the skin 22 to the rim 5 in a proper position allows
proper positioning of the heater 21 with respect to the rim 5.
Moreover, the skin 22 with elongation restrained by the strings 32
can be provided with the characteristics of inward curvature and
easy deformation into a shape suitable for mounting along the outer
surface of the rim 5. Moreover, the heater 21 can easily and surely
be disposed avoiding the holes 50 or stitching portion of the skin
22, leading to prevention of an interference of a needle with the
heater 21 and elimination of breaking of the heater wires 28.
[0069] Furthermore, the skin 22 is formed like a closed loop or
annulus, and is laid on the rim 5 with the heater 21 placed inside.
This facilitates mounting operation of the skin 22 to the rim 5,
and provides uniform tension to the skin 22 to restrain occurrence
of local stretch and wrinkle, allowing enhancement in winding
appearance or product quality.
[0070] Further, the heater 21 is mounted to the skin 22 mainly
through the side edges 26 located at the inner periphery A of the
rim 5, and not fixed thereto through the cross-direction center
located at the outer periphery B of the rim 5. Therefore, even when
the heater 21 undergoes external force, this force does not
concentratedly act on particular narrow area or spots of the heater
wires 28, but is dispersedly applied on the heater 21 by its
movement on the surface of the rim 5 through the net structure,
preventing breaking of the heater wires 28. As described above, the
first embodiment can achieve an enhancement in quality of the
steering wheel 1 with reduced manufacturing cost.
[0071] In the first embodiment, the heater 21 is mounted to the
skin 22 to form an assembly, which is then mounted to the
steering-wheel main body 2. Optionally, after mounting the heater
21 to the steering-wheel main body 2, the skin 22 can be disposed
on the heater 21 for concealment.
[0072] By way of example, referring to FIGS. 6-7, as in the first
embodiment, the inner covering 10 of polyurethane foam is arranged
on all circumferential surface of the core bar 5a of the rim 5 of
the steering-wheel main body 2. The inner covering 10 is covered
with the heater 21 and the skin 22. A parting line C of a mold
produced when forming the inner covering 10 is seen at the inner
periphery A of the rim 5.
[0073] In the second embodiment, as in the first embodiment, the
double-sided tape 33 for fixing the heater 21 is positioned in the
vicinity of the inner periphery A of the rim 5. However, the
double-sided tape 33 is not placed firstly on the heater 21 and the
skin 22, but on the inner covering 10 of the rim 5. Specifically,
firstly, a separator, not shown, is removed from one adhesive face
of the double-sided tape 33 to have the adhesive face exposed,
which is pressed and placed on the surface of the inner covering 10
in a predetermined position, e.g. a position along both sides of
the inner periphery A. At that time, a separator remains disposed
on another adhesive face of the double-sided tape 33.
[0074] Then, the heater 21 is wound on the rim 5. In the second
embodiment, as in the first embodiment, the heater 21 comprises
heater main body 25 obtained by weaving fine heater wires 28 formed
like a net. The transverse center of the heater main body 25 is
positioned at the outer periphery B of the rim 5 to fit the heater
main body 25 on the inner covering 10 by means of self-restoring
force. With the side edges 26 separated at the inner periphery A of
the rim 5 to be opposite to each other, the remaining separator is
removed from the double-sided tape 33 to place the side edges 26
thereon.
[0075] Subsequently, the skin 22 is wound on the heater 21 to form
the steering wheel 1 as shown in FIG. 7. The skin 22 includes a
closed-loop or annular tube-like member having inner diameter
slightly smaller than outer diameter of the rim 5 as the tube-like
member 55 shown in FIG. 1. For winding of the skin 22 on the rim 5,
the tube-like member is enlarged in diameter to engage with the
outer periphery B of the rim 5, then stitched at the inner
periphery A of the rim 5.
[0076] In the second embodiment, the heater 21 is not fixed to the
rim 5 at the outer periphery B wherein the skin 22 is pressed or
rubbed on the inner covering 10 by strong force. Therefore, during
winding operation of the skin 22, even when the skin 22 is rubbed
against the heater 21, the movement of the heater 21 contributes to
prevention of damage or breaking of the heater wires 28 and the net
heater main body 25 in particular spots. This allows achievement of
an intended heating performance of the heater 21 arranged in the
steering-wheel main body 2, leading to enhanced yield. Moreover,
the elongation of the skin 22 can be secured by a large amount,
enabling easy winding of the skin 22 without any wrinkle, resulting
in easy enhancement in product appearance. Moreover, winding of the
skin 22 can be carried out as in the case with no heater 21, i.e.
the steering wheel 1 can be assembled through ordinary operation as
it were. As described above, the second embodiment can achieve an
enhancement in quality of the steering wheel 1 with reduced
manufacturing cost.
[0077] Referring to FIGS. 8A-8B, in the third embodiment, a
protective covering or protector 35 is disposed to conceal the
terminal plate 29 of each terminal 27a, 27b of the heater main body
25 of the heater 21, and particular portions of the heater wires 28
connected to the terminal plate 29 and located in the vicinity of
the terminal plate 29. The protective covering 35 is formed like
roughly a sheet having a rectangular shape when deployed. The
protective covering 35 is formed out of a deformable soft material,
which is a nonwoven fabric of polyester fiber or the like in the
third embodiment. The protective covering 35 is turned back at an
end of the heater 21 to envelop in its entirety the terminal plate
29 and in part the heater main body 25 connected thereto. Moreover,
a rubber adhesive or bonding means is placed on the protective
covering 35 to have upper and lower opposite faces bonded each
other through meshes of the heater main body 25.
[0078] Specifically, the heater 21 conceals the annular rim 5 of
the steering wheel 1, and comprises heater main body 25 including
side edges 26 disposed along the circumferential direction of the
rim 5 and terminals 27a, 27b each arranged at a termination of the
side edges 26 to intersect them, wherein the heater main body
includes a net heating portion obtained by weaving a plurality of
heater wires 28 interconnecting the terminals 27a, 27b. Each
terminal 27a, 27b includes terminal plate or connection 29 for
electrically mechanically connecting the heater wires 28 disposed
in the above direction of intersection. The protective covering 35
is arranged to conceal the terminal plate 29 and part of the heater
main body 25 adjacent thereto.
[0079] In the third embodiment, the protective covering 35 having
intermediate characteristics between very large flexibility of the
net heater main body 25 and small deformation follow-ability of the
terminal plate 29 is disposed at a connection between the heater
main body 25 and the terminal plate 29. Thus, the function of the
characteristics of the protective covering 35 contributes to
alleviation of stress concentration on the connection between the
heater main body 25 and the terminal plate 29, i.e. stress
dispersion, to protect the heater wires 28 of the heater main body
25, preventing breaking of the heater wires 28. This restrains
damage of the heater 21 during assembling of the heater 21 to the
steering-wheel main body 2, allowing preservation of excellent
temperature-rise characteristics. Moreover, this facilitates
handling of the heater 21 in the manufacturing process, allowing
enhanced workability and reduced manufacturing cost.
[0080] Further, the protective covering 35 is disposed in layer
between the heater 21 and the skin 22 for concealing the heater 21
and the rim 5 so as to support and protect the heater 21 together
with the skin 22. This restrains breaking of the heater wires 28,
allowing preservation of excellent temperature-rise
characteristics. Moreover, this facilitates handling of the heater
21 in the manufacturing process, allowing enhanced workability and
reduced manufacturing cost.
[0081] Furthermore, the protective covering 35 is formed out of an
insulative material such as nonwoven fabric, achieving easy
insulation of the terminal plates or feed portions 29 at ends of
the heater 21 from other members.
[0082] In the third embodiment, the protective covering 35 includes
a member different and distinct from the skin 22. Alternatively,
the protective covering may be integrated or integrally formed with
the skin. By way of example, referring to FIGS. 9A-9B, a protective
covering 60 can be obtained by extending a turned-back portion 22a
at a longitudinal end of the skin 22 up to the heater main body 2.
Such integration of the protective covering 60 with the skin 22
allows a reduction in number of parts and manufacturing cost.
[0083] In the fourth embodiment as shown in FIGS. 9A-9B, the
vicinity of each terminal 27a, 27b of the heater 21 is placed on
the skin 22 along both edges 49 by means of a double-sided tape, an
adhesive or the like. As in the first embodiment, the blank 53 is
divided into two equal parts with respect to the aligned holes 50
as center line. Both ends of the skin 22 are sewed to each other
with a thread 22b as shown in FIG. 9B.
[0084] Optionally, the protective covering can be obtained out of
resin in place of a sheet of cloth, leather or the like. By way of
example, referring to FIG. 10, in the fifth embodiment, the
terminal plate 29 is connected at least electrically to the heater
wires 28 of the heater main body 25 by means of soldering or the
like at predetermined spots 61, which is then immersed in liquid
resin, obtaining a protective covering 63. Examples of preferable
resins for forming the protective covering 63 are vinyl chloride
and natural rubber.
[0085] In the illustrative embodiments, for enhanced workability,
the longitudinal ends of the skin 22 are butted each other to form
an annular or closed-loop member, which is then engaged with the
rim 5. Optionally, after winding the band-like skin 22 on the rim 5
of the steering-wheel main body 2, the opposite ends of the skin 22
may be joined through sewing or the like.
[0086] Referring to FIGS. 11-12, in the sixth embodiment, the
steering-wheel main body 2 further comprises heat transfer means 70
including a plurality of metal plates or aluminum sheets 70a, 70b,
70b, 70c. Each aluminum sheet 70a, 70b, 70b, 70c is disposed at the
inner periphery A of the rim 5 and between the spokes 7. The inner
covering 10 is formed with recesses 10a having different widths,
lengths and depths to receive the aluminum sheets 70a, 70b, 70b,
70c. When engaged with the recesses 10a, the aluminum sheets 70a,
70b, 70b, 70c have surfaces continuously connected to the surface
of the inner covering 10, providing a roughly flat and single
surface to the rim 5. In the sixth embodiment, the aluminum sheets
70a, 70b, 70b, 70c have 28 mm width W and 0.3 mm thickness, and are
adhesively placed in the recesses 10a, respectively.
[0087] As described before, the skin 22 elongated at the outer
periphery B of the rim 5 is inclined inwardly to wind the rim 5,
and then disposed along the surface of the rim 5 to adhere thereto
by means of the double-sided tapes for temporary fixing. In this
state, as shown in FIG. 12, the side edges 26 of the heater 21 are
disposed on both sides of the aluminum sheets 70a, 70b, 70b, 70c of
the heat transfer means 70.
[0088] As shown in FIG. 12, the edges 49 of the skin 22 are butted
each other on the inner periphery A of the rim 5 in a position C,
and stitched with thread of polyester or the like which passes
through the stitch holes. Stitches E are provided in a range W1 of
about 8 mm in the circumferential direction of the section of the
rim 5. The heater 21 is disposed at a distance of an additional
space W2 of 2 mm away from the range W1 so as to avoid interference
or contact of a needle with the heater 21 during stitching of the
skin 22. The width of a superimposition W3 of each aluminum sheets
70a, 70b, 70b, 70c on the heater 21 is 8 mm.
[0089] When the heater 21 is energized through lead wires, the
heater main body 25 provides heat except the rim 5 at the perimeter
of the stitches E, achieving a temperature rise of the surface of
the rim 5 through the skin 22. The portion of the rim 5 having
stitches E is not directly heated by the heater main body 25.
However, since both sides of the heater main body 25 are in contact
with the superimposition W3 of the aluminum sheets 70a, 70b, 70b,
70c to warm the aluminum sheets, through which the skin 22 in the
vicinity of the edges 49 is warmed. In such a way, the skin 22 is
warmed in its entirety including a portion having stitches E in the
vicinity of the edges 49.
[0090] As described above, the sixth embodiment shows heater 21 for
covering the annular rim 5 of the vehicular steering wheel 1,
wherein the heater 21 is arranged merely on part of the surface of
the rim 5, and the heat transfer means 70 partly superimposed on
the heater 21 is arranged on remaining part of the surface of the
rim 5. Thus, heat generated by the heater 21 is promptly
circumferentially transferred to the rim 5 through the heat
transfer means 70, achieving substantially uniform heating of the
rim 5 along all circumference of the section thereof, resulting in
enhanced operation feel of the steering wheel 1. This structure
allows the heater 21 not to extend exactly to the vicinity of the
edges 49 of the skin 22.
[0091] In the sixth embodiment, the edges 49 of the skin 22 that
conceals the rim 5, the heater 21 and the heat transfer means 70
are circumferentially disposed at the inner periphery A of the rim
5, and are butted each other for stitching. Since the heat transfer
means 70 are disposed along the edges 49 of the skin 22, i.e. the
heater 21 is not disposed along them, the portion of the skin 22
having stitches E, i.e. stitched portion of the edges 49, is not
superimposed on the heater 21, but on the heat transfer means 70
only, preventing damage of the heater wires 28 of the heater 21
from a needle. Moreover, the heater 21 is arranged astride a butt
portion of the edges 49 of the skin 22, providing sufficient
heating of the portion of the skin 22 having stitches E.
[0092] Further, the heat transfer means 70 have both sides
superimposed on the side edges 26 of the heater 21, receiving heat
from two directions, resulting in achievement of effective
heating.
[0093] Still further, the heat transfer means 70 include thin metal
sheets with excellent heat conductivity such as aluminum sheets
70a, 70b, 70b, 70c, allowing easy achievement of the structure
suitable for heating of the rim or grip 5.
[0094] In the sixth embodiment, the heat transfer means 70 are
disposed on the rim 5, and the heater 21 is in turn disposed on the
heat transfer means 70. Alternatively, the heat transfer means 70
may be disposed on the heater 21. Moreover, the heat transfer means
70 can be extended to the spokes to provide a heat-transfer effect
to particular portions of the spokes in the vicinity of junctions
with the rim 5.
[0095] Having described the present invention with regard to the
preferred embodiments, it is noted that the present invention is
not limited thereto, and various changes and modifications can be
made without departing from the scope of the present invention.
[0096] The entire teachings of Japanese Patent Applications
2000-287360, 2000-289200, 2000-301025, and 2000-291315 are
incorporated hereby by reference.
* * * * *