Note: Descriptions are shown in the official language in which they were submitted.
1323~91
WHEEL COVER
The present application is a division of Application
Serial No. 543,556 filed July 31, 1987.
The present invention relates to an automobile wheel
cover, and, more particularly, to a wheel cover that, when
fixed to a wheel, has a plurality of holding claws protruding
from its rear surface tha~ are urged in the radially outward
direction toward the rim of the wheel by means of a resilient
ring.
To enable the prior art to be described with the aid
of diagrams the figures of the drawings will first be listed.
Figs. 1 and 2 are respectively a rear view and a
cross sectional view of a main portion of a conventional wheel
cover:
Fig. 3 is a plan view showing a wire ring of another
conventional wheel cover;
Figs. 4 and 5 are a perspective view and a rear
view, respectively, showing a rear main portion of a wheel
cover of E~bodiment l according to the present invention;
Figs. 6 and 7 (with Fig. 4) are respectively cross
sectional views taken on line VI-VI and line VII-VII of Fig.
5;
Fig. 8 (with-Fig. 5~ is a top plan view of a holding
claw according to Embodiment l;
Fig. 9 (with Fig. 5) is a cross sectional view taken
on line IX-IX of Fig. 5:
1323391
-- 2
Figs. 10 and 11 are cross sectional views of the
main portion of the wheel cover attached to a wheel;
Figs. 12 and 13 are explanatory views showing the
movement of the metal mold when molding the holding claws of
the wheel cover according to Embodiment l;
Fig. 14 is a perspective view of a holding claw
of a wheel cover according to Embodiment 2 of the present
invention;
Fig. 15 is a schematic rear view of a wheel cover
having the holding claw shown in Fig. 14;
Fig. 16 is a schematic rear view of the wheel
cover;
Fig. 17 is a vertical sectional view of the holding
claw;
Fig. 18 is a top plan view of the holding claw as
shown in Figs. 14 - 17;
Fig. 19 is an explanatory view according to
; Embodiment 2 showing the movement of the metal mold when
molding the holding claw;
Fig. 20 is a sectional view of the main portion of
the wheel cover according to Embodiment 2 showing the
engagement of the wheel cover and wheel;
Fig. 21 is an enlarged explanatory side view of
the holding claw as shown in Fig. 14;
Figs. 22A, 22B and 22C are respective explanatory
views showing the process of fitting the holding claw to the
wheel;
Figs. 23A, 23B and 23C are respective graphs showing
the relationships of the values of S, a, l/tan 0, and F with
respect to the bending degree of the holding claw;
Figs. 24 and 25 are perspective explanatory views
showing the holding claw shown in Fig. 14;
Fig. 26 is a perspective view of a holding claw oî
a wheel cover according to Embodiment 3 of the present
invention;
:
1323391
-- 3
Fig. 27 is a schematic rear view of the wheel cover
shown in Fig. 26;
Fig. 28 is an enlarged top plan view of the holding
claw and support members shown in Fig. 27;
Fig. 29 is a vertical sectional view according to
Embodiment 3, showing the configuration wherein the holding
claw engaged with a wire ring and a rim of the wheel are
being pressed together;
Fig. 30 is a front view of the holding claw shown
in Fig. 26;
Fig. 31 is an explanatory view according to
Embodiment 3, showing the movement of the metal mold when
molding the holding claw;
Fig. 32 is a top plan view similar to Fig. 28,
showing a modification of Embodiment 3;
Fig. 33 is an explanatory view showing the
relationship between the holding claw and wheel rim of the
foregoing wheel cover, as shown in Fig. 10, therein serially
presenting: an explanatory view (a) of the arrangement of
the wheel and the holding claw; a moment diagram (b) in
terms of the component force Ps, in the axial direction of
the leg portion, acting on the leg portion of the holding
claw; a moment diagram ~c) in terms of the radial component
force Pr; and a moment diagram (d) showing the sum of both
the foregoing moment diagrams;
Fig. 34 is an explanatory view showing the
relationship between the configuration of the head portion
of the holding claw and wheel rim, as shown in Fig. 10;
Fig. 35 is a rear view showing a part of a wheel
cover according to Embodiment 4 of the present invention;
Fig. 36 is a sectional view of the essential part
of the wheel cover according to Embodiment 4 which is mounted
on a wheel; and
Fig. 37 - Fig. 39 are respectively enlarged
sectional views of the leg portion of the holding claw
according to modifications of Embodiment 4.
_ 4 _ 1~3391
Conventional wheel covers have a variety of
constructions: for example, a wheel cover as shown in Figs. 1
and 2 is described in Japanese Patent Publication
No. 67602/1981. Referring to Figs. 1 and 2, a plurality of
S holding claws 22 are formed on the rear surface of a wheel
cover main body 21, a groove 22a is formed on the radially
inside surface of each holding claw 22, and a base portion
23b of an arch-shaped protrusion 23a of a wire ring 23 is
pressed-into contact with stoppers 24 formed on both sides
of the holding claw 22 so as to protrude from the rear surface
of the wheel cover main body, whereby the radially outwardly
spreading force of the wire ring 23 is received by the
stoppers 24. When the holding claws 22 are radially inwardly
bent during a mounting operation of the wheel cover onto the
wheel, the protrusion 23a of the wire ring 23 is also bent,
thereby applying the resilient force of the wire ring 23 as
well as the resilient force of the holding claw. Thus a
large resilient force is applied to the holding claw 22,
even with only a slight degree of bending of the holding claw
22. In this construction, when fitting the wheel cover 21 to
the wheel, some of the holding claws 22 are first bent towards
the central portion of the wheel cover so as to abut the
wheel rim. Then the rest of the holding claws are gradually
bent towards this central portion so as to fit the entire
wheel cover to the wheel rim, whereby the holding claws are
pressed into contact with the wheel rim with the aid of the
foregoing resilient force, in order to fit the wheel cover 21
to the wheel.
Another construction of a conventional wheel cover
is shown in Fig. 3 and is described in Japanese Patent
Publication No. 67601/1981. The wheel cover in Fig. 3 has
basically the same construction as the one described above;
however the construction of the wire ring is altered, as
shown in Fig. 3, namely the ratio of the radial dimension R
rrom the center of the wire ring 27 to a protrusion 27a and
the radial dimension r from the center to a base portion 27b
~ 5 ~ 1 ~ 2 3 3 9 1
of a protrusion 27a, is so chosen, that, as shown by dotted
lines in the drawing, when the protrusion 27a is bent inwardly
toward the central portion with the aid of the holding claw,
the base portion 27b is also bent in the same direction
together with the holding claw. Thus the protrusion 27a of
the wire ring 27 is provided with a large stroke to resist the
resilient force of the wire ring and the foregoing holding
claw by utilizing a large vacant space within the wheel rim.
According to the construction described above,
however, the wire ring is provided with a multiplicity of
protrusions, whereby the number of shaping procedures when
making the protrusions is large, thus increasing the
production cost. If the number of protrusions is reduced to
lower the cost, the number of holding claws corresponding to
the protrusions is also reduced, resulting in an increased
holding force applied on the wheel rim by each holding claw.
As a result, the degree of bending of each holding claw is
increased and the wheel cover is difficult to fit onto the
wheel. Furthermore, there is no regulating means for bending
the wire ring in the radially inside portion of the wire ring.
This causes the wire ring to bend freely so that it is apt to
become removed from the holding claw.
The object of the present invention is to solve
these disadvantages and, more particularly, to provide a wheel
cover that can be produced at a lower cost, that is easy to
fit onto a wheel, and, once fitted, that is firmly secured
with the aid of the resilience force of the holding claws as
well as the resilient ring.
To achieve the foregoing object, according to the
present invention, there is provided a wheel cover for a motor
vehicle comprising: a synthetic-resin-made wheel cover main
body having a plurality of holding claws integrally circum-
ferentially formed on a rear surface thereof; said holding
claws being provided with an engaging portion formed on a
radial outside surface of a head portion thereof; a resilient
reinforcement ring having approximately the same diameter as a
diameter defined by said holding claws; each of said plurality
of holding claws having a projection integrally formed on the
.
1~233~1
-- 6 ~
radial inside surface of the head portion of said claw, said
projection protruding substantially inwardly in the radial
direction with respect to the radial inside surface of said
head portion and including a wire-ring engaging surface which
engages and holds said resilient reinforcement ring; said
resilient reinforcement ring being inserted into said wire-
ring engaging surface, whereby the wire-ring engaging surfaces
of each of said holding claws, when said wheel cover is
removably fitted to a wheel, are pressed to contact with a rim
of the wheel by an inherent resilience of said holding claws
and said resilient reinforcement ring; and an opening radially
penetrating said claw and being positioned under the
projection, wherein a metal mold is positionable within said
opening for integrally forming the wire-ring engaging surface
when molding the wheel cover.
Embodiment 1
Figs. 4 - 11 show Embodiment 1 according to the
present invention.
Referring to ~igs. 4 and 5, a wheel cover 1 is
provided with a plurality of holding claws 4 formed on the
rear surface of a synthetic-resin main body 5, support members
3 being arranged between adjacent holding claws 4. A
circular, resilient, metal wire ring 2 is engaged with the
holding claws 4 and support members 3, the radial movement of
the wire ring 2 being regulated by the support members 3.
This wheel cover 1 is composed of an approximately
circular plate, i.e. the main body 5, a multiplicity of the
holding claws 4 and support members 3 being formed integrally
at regular intervals on the rear surface of the circular plate
5, and an opening 7 for allowing air to flow therethrough,
_ 7 _ 13 2 33 91
which is surrounded by a reinforcement wall 6 formed between
a holding claw 4a and a pair of support members 3.
A plurality of holding claws 4 are, as shown in
Fig. 4, formed at regular intervals on the rear surface of
the main body 5. As shown in Figs. 6 - 8, each holding claw
4 comprises a leg portion 4b protruding from the rear surface
of the body 5, and a pair of head portions 4a formed at the
tip of the leg portion 4b. The radial outside surface of
the head portion 4a is provided with an engaging portion 4d
protruding in the form of a triangle in cross section, so as
to engage with a concave portion 8b of a rim 8a of a wheel 8.
A groove 4e is formed on the radial inside surface of the
head portion 4a. A wire ring 2 is inserted into the groove
4e. The upper surface of the groove 4e is provided with a first
protrusion 4f, and the lower surface of the groove 4e is
provided with a second protrusion 4g. A third protrusion 4h
is formed at the portion corresponding to the second protrusion
4g and below a space 4c between the pair of head portions 4a.
The wire ring 2 in the groove 4e is thus engaged with the
first protrusion 4f and the second protrusion 4g, and, at
the same time, the ring 2 between both head portions 4a and
4a is supported by the third protrusion 4h, thereby
positioning the ring 2. The first protrusion 4f is formed to
protrude radially inwardly more than the second protrusion
4g, so as to prevent the ring 2 from being removed from the
groove 4e in the upward direction as seen in Figs. 6 and 7.
The leg portion 4b is so flexible that, when the
ring 2 is inserted into the groove 4e and subsequently when the
wheel cover 1 is fitted onto the wheel 8, the leg portion 4b
is slightly, radially, and resiliently able to bend, so as to
allow the ring 2 to be smoothly slightly inserted into the
groove 4e, as well as the wheel cover 1 to be fitted onto the
wheel 8.
Moreover, a pair of support members 3 is formed
between adjacent holding claws 4. Each support member 3 is
a plate arranged on the rear surface of the body 5. The
.
- 8 - 1~2339~
surface of this plate 3 extends in the radial direction.
The plate 3 has sufficient thickness and width so as not to
be deformed even if a radial force is applied to it, and not
to be excessively bent even if a circumferential force is
applied. Also, the support member 3 is connected to the
reinforcement wall 6 through a plate 9 so as to be securely
prevented from being excessively bent circumferentially by
any force applied circumferentially thereto.
The support member 3 described above is, as shown
in Fig. 9, provided with a pair of protrusions 3a and 3c
formed respectively at radially outside and inside portions
of an upper surface confronting the wheel, and a groove 3b
extending radially between the protrusions 3a and 3c, whereby
the ring 2 can be radially moved into the groove 3b located
between the protrusions 3a and 3c. The height hl of the
first protrusion 3a with respect to the groove bottom surface,
is made greater than the height h2 of the second protrusion
3c with respect to the groove bottom surface, and greater than
the diameter of the wire ring 2, thereby preventing the ring
2 in the groove 3b from expanding radially outwardly. The
second protrusion 3c is made lower than the first protrusion
3a, so that the ring 2 can be easily inserted into the groove
3b. Hence, the ring 2 is inserted into the groove 3b from
a radially inside position over the second protrusion 3c
towards the outside. The second protrusion 3c prevents the
ring 2 from being removed from the groove 3b when it is
inserted into the groove 3b.
A groove end surface 3d of the first protrusion 3a
is located on the circumference of the groove end surface 4i
of the holding claw 4, or slightly radially outside the
circumference of such surface 4i, whereby the ring 2 when
inserted into the groove 4e of the holding claw 4 has a small
clearance 11 between the end surface 3d of the first
protrusions 3a and end surface 4i of the holding claw 4.
According to this construction, the wire ring 2 can exert a
- ' ' ~ ~ .
, .
9 1323391
resilient force much greater on the holding claw 4 than on
the support member 3 by the amount caused by the clearance 11,
whereby the wheel cover 1 can be securely held and pressed
into contact with the wheel 8. The radial length L of the
groove 3b of the support member 3 is so formed as to allow
the wire ring 2 to deform or to move due to the bending of
the holding claw 4 when fitting the wheel cover 1 to the wheel
8, while this radial length L should not allow the ring 2 to
deform or move when an excessive bending is generated on the
holding claw 4. Also, the height H2 of the bottom surface of
the groove 4e from the reference surface of the wheel cover 1
is made lower than the height Hl of the bottom surface of the
holding claw 4 from the reference surface of the wheel cover
1. Therefore, the ring 2 can move in the groove 3b of the
support member 3, and the ring 2 is prevented from falling to
the rear surface of the body 5 between the holding claws 4.
In addition, when the wheel cover 1 is fitted to the wheel 8
in a normal manner, a clearance 10 is maintained between the
outside end surface 3e of the support member 3 and the rim 8a
of the wheel 8. Thus, if an excessively eccentric load is
applied to the wheel cover 1, the support member 3 is pressed
into contact with the wheel 8 so as to eliminate the clearance
10, thereby preventing an excessive bending of the wheel
cover.
According to the construction described above and
shown in Fig. 4, the wire ring 2 is inserted into the grooves
4e of the holding claw 4 from over the rear surface of the
main body 5 with the holding claws 4 bent radially outwardly;
then the ring 2 is supported by the grooves 3b of the support
members 3 so as to be radially movable. When the ring 2 is
inserted into the groove 4e of the holding claw 4, the ring
is slightly bent, and thus the resilient force exerted by
this bending movement acts on the holding claw 4, pressing
the same slightly radially outwardly. Further, as shown in
Figs. 10 and 11, when some holding claws 4 of the wheel cover
1 to which the ring 2 is fitted, are pressed into contact with
. . - ,. ,
, ~
: .
. .
1323391
-- 10 --
the rim 8a of the wheel 8, those holding claws 4 and the ring
2 in the grooves 4e of the holding claws 4 are bent radially
inwardly together. At this time, the portion other than the
portion to which the bending force of the ring 2 is applied,
is apt to extend radially outwardly. Subsequently, when some
holding claws 4 are pressed into the wheel 8, the rest of the
holding claws 4 are also apt to extend outwardly. However,
they are prevented from outward movement by the first
protrusion 3a of the groove 3b of the support member 3.
Accordingly, all the holding claws 4 can be easily bent
radially inwardly, and the wheel cover l is fitted to the
wheel 8. Moreover, the wheel cover l is fitted in the wheel
8 together with the holding claw 4, with the ring 2 being bent,
whereby the engaging portion 4d is engaged with the concave
portion 8b of the rim 8a of the wheel 8 with the aid of the
combined resilient force exerted by the ring 2 and the holding
claw itself, so that the wheel cover l is securely fitted to
the wheel 8. The wheel cover l can be removed from the
wheel 8 by releasing the engagement of some holding claws 4
of the wheel cover l with respect to the rim 8a.
According to the embodiment described above, the
support members 3 are formed, at the adjacent holding claws
4, on the rear surface of the main body 5, and the wire ring
2 is inserted into the grooves 4e of the holding claws 4 as
well as into the grooves 3b of the support members 3, whereby,
when the wheel cover l is fitted to the wheel, some holding
claws 4 are bent towards the central portion together with
the wire ring 2. The rest of the holding claws 4 are apt to
extend radially outwardly due to the resilient force exerted
by the deformed wire ring 2. However, since the first
protrusions 3a of the grooves 3b of the support members 3
prevent the wire ring 2 from moving radially outwardly, the
rest of the holding claws 4 can be bent inwardly toward the
central portion with a relatively small force. This arrange-
ment facilitates fitting of the wheel cover l onto the wheel8. Also, even if an external force is applied to the holding
1323391
claws 4 so as to deform some holding claws 4 excessively, the
radial movement of the wire ring 2 is restricted by both
protrusions 3a and 3c of the support member 3, whereby the
holding claw 4 is effectively prevented from being
excessively deformed by the ring 2. When the wheel cover 1
is fitted to the wheel 18, the holding claws 4 are securely
pressed into contact with the rim 8a of the wheel8 by means
of the combined resilient force of the holding claws 4
themselves and the wire ring 2, thus making the fitting
secure.
It is to be noted that various changes and
modifications will be apparent to those skilled in the art.
For example, the support member 3 may be integrally formed
with the reinforcement wall 6, and the holding claws 4 may
be formed in any desired number provided that they can
effectively perform the same function as described above. In
addition, a plate member 9 independent of the reinforcement
wall 6, may radially reinforce the support member 3 with
respect to the wheel cover main body 5. Reinforcement of the
support member 3 is not limited to a configuration wherein a
plate member 9 is formed at one side of the support member 3,
- but the support member 3 can be reinforced by two plate
members formed on both sides.
Embodiment 2
The wheel cover according to Embodiment 1 has the
following disadvantage. Referring to Fig. 12, which
schematically shows a holding claw 4, when forming holding
claws on the wheel cover main body, a metal mold portion A,
which is positioned inside the holding claws 4 and which
forms the inside surface of the holding claw having the
groove 4e is, as shown in Fig. 13, drawn upwardly after
completion of the injection molding so as to bend the
holding claws radially outwardly.
At this time, the forcible drawing distance d is
restricted by the length h of the holding claws. The guide
!.
' .
- 12 - 13233~1
distance D of the tip portion of the holding claw 4 is also
restricted. As a result, when mounting the wheel cover on
the rim of a wheel, the tip portion of the holding claw cannot
be sufficiently guided with respect to the wheel. Therefore,
the holding claws are not smoothly bent toward the central
portion of the wheel cover main body, nor is the wheel cover
smoothly fitted onto the wheel. Furthermore, the wire ring
may be removed during transportation of the wheel cover.
Accordingly, the object of Embodiment 2 is to over-
10 come this disadvantage, i.e., to provide a wheel coverwherein the holding claws have sufficient strength, a
resilient ring, such as the wire ring, can be securely engaged
- with the holding claw, and, moreover, the wheel can easily be
fitted onto the wheel cover.
Figs. 14 through 20 shows Embodiment 2.
Referring to Figs. 14 - 16, a wheel cover 101 has
a construction wherein a plurality of holding claws 104 is
provided on the rear surface of the wheel cover main body 105.
Protrusions 104f are integrally formed on the circumferential
20 side ends of each holding claw 104. Support members 103 are
formed at both sides of each holding claw 104. A circular metal
wire ring 102 serving as the resilient member is engaged with
two protrusions 104f of the holding claws 104 and the support
members 103. Accordingly, radial movement of the wire ring
25 102 is generally controlled by the support members 103.
The wheel cover 101 generally comprises a wheel cover
body, i.e., a circular plate, a multiplicity of holding claws
104 and support members 103 integrally circumferentially
formed on its rear surface at regular intervals. A plurality
30 of holding claws 104 is, as shown in Fig. 16, arranged at
regular intervals on the rear surface of the main body 105.
Each holding claw 104 generally comprises a leg portion 104b
protruding from the rear surface of the main body 105, and a
head portion 104a having a groove 104e, formed at the tip
35 portion of the leg portion 104b, into which the ring 102 is
inserted. The radial outside surface of the head portion
132~3~1
- 13 -
104a is provided with an engaging portion 104d protruding
outwardly, which is to be engaged with a concave portion
108b of a rim 108a of the wheel 108. The groove 104e is formed
on the inside surface of the head portion 104a, into which
the ring 102 is inserted. A protrusion 104f is in the form of
a triangle in cross-section at both ends of the head portion
104a of the holding claw 104 in the circumferential direction.
The radial inside tip portion of each protrusion 104f protrudes
radially inwardly over the inside surface of the groove 104e
and the ring 102 fitted in the groove 104e. The lower surface
of each protrusion 104f is an incline 104g that is slanted
radially from outside to inside so as to approach the main
body 105. The angle formed by the radial inside surface of
the head portion 104a of the holding claw and the incline
104g is less than 90 degrees. The ring 102 inserted into the
groove 104e is engaged with both protrusions 104f. In this
case, since the leg portion 104b of the holding claw 104 is
flexible, it can bend resiliently with respect to the rear
surface of the main body 105, so that the ring 102 can be
inserted smoothly and slightly into the groove 104e. Further-
more, when the wheel cover 101 is fitted into the wheel 108,
the leg portion 104b allows each holding claw 104 to bend
easily in the radially inward direction, thereby facilitating
fitting the wheel cover 101 smoothly into the wheel 108. The
portion 104d is provided with concave portions 104h to prevent
a sink, which is liable to occur when injection-molding the
holding claws.
The above-described holding claw 104 is formed, as
shown in Figs. 18 and 19, by a conventional molding method
using the following metal molds; a pair of radially-movable
first molds 106 for molding the incline 104g of each
protrusion 104f, a second mold 107 for molding the radially
outside surface of the holding claw 104, and a third mold 109
for molding the groove 104e and the radially inside surface of
the holding claw 104. Each of the molds 106 is provided with
13233~1
- 14 -
an incline 106f slanting toward the central portion of the
main body. The first mold 106 molds the protrusion 104f with
the aid of the second mold 107 and third mold 109.
The first support member 103 is made of an
approximately rectangular plate which is positioned on the
rear surface of the wheel cover 104 in such a way that the
plate surface extends in the radial direction and has enough
width and thickness not to bend when subjected to the radial
and circumferential forces. At the top end surface of each
10 first support member 103 there is formed a groove 103a which
controls the radial movement of the ring 102 so that the ring
102 does not move excessively in the radial direction in
conjunction with the holding claw 104.
According to this construction, the ring 102 is
inserted into the groove 104e and is engaged with both
protrusions 104f, with the holding claw 104 bending outwardly
in the radial direction. The ring 102 is also inserted into
and supported by a groove 103a of the first support member
103 so as to be movable in the radial direction. When the
20 ring 102 is inserted into the groove 104e of each holding claw
104, the ring 102 is slightly deformed. The resilient force
generated by this bending motion acts on the groove 104e of
each holding claw 104, and slightly presses each holding claw
104 outwardly in the radial direction. Moreover, as shown in
25 Fig. 20, when the holding claws 104 of the wheel cover 1,
wherein the ring 102 is fitted, are pressed into contact with
the rim 108a of the wheel 108 and the holding claws are bent
inwardly in the radial direction, the ring 102 in the groove
104e of the holding claws 104 is bent inwardly in the radial
direction together with the holding claws 104. The engaging
portion 104d is engaged with the concave portion 108b of the
rim 108a of the wheel 108 with the aid of the combined
resilient force exerted by the ring 102 and the holding claws
104 themselves, so that the wheel cover 101 is securely
35 attached to the wheel 108. The wheel cover 101 can be removed
-
13233~1
- 15 -
from the wheel 108 by releasing the engagement of some holding
claws 104 with respect to the rim 108a.
In Embodiment 2, as described above, both ends of the
holding claw 104 are provided with a protrusion 104f, and the
inside surface of the head portion 104a and the protrusions
104f are circumferentially positioned at different locations
so as to be molded by the molds 106, 106, 107, and 109 which
slide radially and the incline 104g of each protrusion 104f is
formed so as to slant radially inwardly with respect to the
wheel cover main body. Therefore, the angle formed by the
inside surface of the head portion 104a of the holding claw
and the incline 104g is less than 90 degrees, and the ring 102
is thus securely engaged with the protrusion 104f, without
fear that the wire ring may be displaced.
Also, the holding claws 104 are formed by moving the
molds 106, 106, 107 and 109 approximately along the rear surface
of the main body 105, whereby the leg portion 104b of each
holding claw 104 can be easily formed to have a sufficient
thickness and thus be provided with sufficient strength.
Further, protrusions 104f are formed on both side ends of the
holding claw 104, and the ring 102 is inserted into the grooves
104e of the holding claws 104 as well as being engaged with
the foregoing protrusions 104f. After the wheel cover 101 is
fitted onto the wheel 108, the holding claws 104 can be
securely pressed into contact with the rim 108a of the wheel
108 with the aid of the resilient force generated by the wire
ring 102 and the resilience force of the holding claws 104
themselves, so that the wheel cover 101 can be securely fitted
onto the wheel 108.
Alternatively, the configuration of the holding
claw 104 and protrusion 104f may be of any desired type
provided that it functions in the same way as in the
embodiment described above. Furthermore, the holding claw 104
can be constructed to have no groove 104e, but instead, the
ring 102 can be simply abutted against the inside surface of
the head portion 104a, or the ring 102 may be arranged facing
- 16 - 13233~1
the inside surface with a small clearance therebetween.
The configuration of the outside surface of the
head portion 104a of the holding claw 104 greatly influences
the degree of easiness of fitting the wheel cover 101 to the
wheel. As clearly shown in Figs. 21, 22A, 22s, and 22C, when
the wheel cover 101 is fitted onto the wheel 108, the outside
surface 104h of the head portion 104a abuts the curved portion
108b of the rim 108a of the wheel 108, thereby causing a
frictional resistance.
The outside surface 104h of the head portion 104a
normally comprises a flat surface 104i, as shown by dotted
lines in Fig. 21, followed by a curved surface 104j. However,
the inventors of the present invention have found through
various experiments that a gently curved surface 104k as
shown by solid lines in Fig. 21 is better than the flat
surface 104i; the following description deals with the
configuration of the gently curved surface 104k:
Figs. 22A through 22C show that the holding claw
104 slides on the curved surface 108b of the wheel 108; Fig.
22A shows the initial stage, Fig. 22B shows the intermediate
stage, and Fig. 22C shows the final stage.
Supposing that with respect to the pressing force
of the wheel cover against the wheel, N represents a
perpendicular reaction force against the curved surface 108b
of the holding claw 104, F represents a component of force
(pressing force) N in the pressing direction onto the wheel
cover, and S represents a perpendicular component of the force
(reaction force of the ring 102) N in the pressing direction.
- The relationships of the forces can be stated in the equation
shown below; where 0 represents the angle formed by the tangent
line of the holding claw 104 and curved surface 108b with
respect to the perpendicular line in the pressing direction.
The relationship between S and F can be stated in the
equation:
F = S
tan~
13233~1
- 17 -
(A) Initial stage (Fig. 22A)
N : small
S : small
F : small
: large
tan9
(s) Intermediate stage (Fig. 22s)
N : medium
S : medium
F ; large
: large
tan3
(C) Final stage (Fig. 22C)
N : large
S : large
F : small
tan~
The pressing force F thus becomes maximum in the
intermediate stage of fitting the wheel cover onto the wheel.
To reduce the pressing force F, the value of l/tan ~ should -
be reduced, i.e., the value of 6 should be increased. The
inventors of the present invention have found that the value
of the pressing force F can be generally reduced by
manipulating the value ~, i.e., by making this value in
accordance with the solid line representing the curved surface
104k in Fig. 21. Figs. 23A through 23D show the relationships
between S, ~, l/tan ~, and F with respect to the degree of
bending of the holding claw.
g ~ (P2), and (P3) show the initial
stage, intermediate stage, and the final stage corresponding
to Fig. 22A, Fig. 22B, and Fig. 22C, respectively. As shown
in the figures, in the initial stage, the value ~ of the flat
1323391
- 18 -
surface 104i is larger than that of the curved surface 104k
(Fig. 23B); accordingly, regarding the curved surface 104k,
l/tan ~ is large, and F is also small (Fig. 23D). In the
intermediate stage and final stage, however, the value ~ of the
S curved surface 104k is larger than that of the flat surface
104i (Fig. 23B); accordingly, regarding the curved surface
104k, l/tan a is small, and F is also small. In other words,
it is apparent that the pressing force F can be generally
made small when the outside surface 104h of the holding claw
10 104 is so formed as the curved surface 104k rather than as the
flat surface 104i.
Embodiment 3
Embodiment 3, as shown in Figs. 26 through 32, is an
improvement of Embodiment 2. Embodiment 2 has the disadvantage
that will be described by making reference to Figs. 24 and 25.
It is to be noted that the wheel cover is generally formed by
way of injection molding. As shown in Figs. 24 and 25, the
engaging surface 104g of the protrusion 104f protruding
inwardly from the inside surface 104q of the head portion in
the radial direction, is formed by means of the outer mold
10~ (Fig. 19), thereby permitting the engaging-surface-forming
portion of the outer mold to locate radially inside the leg
portion 104b of the holding claw 104. Therefore, in order to
draw outwardly the outer mold 104p upon completion of the
molding process, the leg portion 104b must have approximately
the same width from its base portion 104m to a connection
portion 104m of the head portion. If the leg portion 21e is,
as shown by the dotted line 104Q in Fig. 25, so formed that
its width increases from the connection portion 104n of the
head portion toward the base portion 104m, a triangle portion
104p behind the portion lOQ remains when the mold is drawn
inwardly, i.e, in the direction shown by the arrow X in
Fig. 25. In this case, one proposal would be to draw the
mold inwardly, but due to the restrictions arising from the
design of the wheel cover, the mold cannot be drawn inwardly;
- 19 _ ~323391
thus, the leg portion 104b has to be of approximately the
same width from the head portion to the leg portion, resulting
in an excessive stress at the base portion 104m.
Accordingly, the object of Embodiment 3 is to solve
this problem, i.e., to provide a wheel cover wherein the
holding claw has sufficient strength and a leg portion is
formed whose width increases from the connection portion of
the head portion toward the base portion, resulting in
sufficient strength.
Referring to Figs. 26 through 31, a wheel cover 201
is generally so constructed that, as shown in Fig. 27, a
plurality of holding claws 204 are formed on the rear surface
of a wheel cover main body 205 that is made of synthetic resin.
The holding claw 204 comprises a head portion 204a and a leg
portion 204b. A slit 204c is formed in the leg portion 204b.
On the head portion 204a there is formed a protrusion 204f
which engages and holds a wire ring 202 used as a reinforce-
ment resilient member. The ring 202, having approximately the
same diameter as the circumference wherein the holding claw
204 is arranged, is arranged on the rear surface of the main
body 205 and positioned radially inside the holding claw 204 to
be engaged and held by the protrusion 204f. Therefore, when
the wheel cover is removably fitted onto the wheel 208, each
holding claw 204 is pressed into contact with the rim 208a of
the wheel 208 with the aid of the resilience of the ring 202
and the holding claw 204, whereby the wheel cover 201 is
mounted on the wheel 208.
The main body 205 is formed approximately into the
shape of a disc. A plurality of holding claws 204 and support
member 203 are integrally formed with the main body 205 at
regular intervals in the circumferential direction and on the
rear surface thereof.
The holding claw 204 comprises the leg portion 204b
protruding from the rear surface of the main body 205, and the
head portion 204a formed at the tip of the leg portion 204b.
-.
- 20 - 1323391
The leg portion 204b is so formed that its
circumferential width L gradually increases from the portion
204n connected with the head portion toward the base portion
204m which connects to the main body 205, whereby the stress
on the holding claw 204 can be made uniform over the entire
area of the leg portion 204b. Also, the ring 202 is abutted
against the inside surface 204e of the head portion so as to
be engaged with the protrusion 204f. In this case, the leg
portion 204b is flexible and accordingly slightly and
resiliently bends with respect to the rear surface of the
main body 205. Therefore, the leg portion 204b allows the
ring 202 to abut smoothly on the inside surface 204e of the
head portion. Furthermore, when the wheel cover 201 is to be
fitted onto the wheel 208, the leg portion 204b allows each
lS holding claw 204 to bend easily in the radial direction,
thereby facilitating fitting the wheel cover 201 smoothly onto
the wheel 208. In both circumferential end surfaces of the
base portion 204m of the leg portion 204b,i.e.~ a side surface 204j
in the radial direction, a curved surface 204i is formed at
the portion connecting each side surface 204j and the main
body 205, thereby eliminating stress concentration on the
connection portion. In the widthwise central portion of the
leg portion 204b, the slit 204c extends from the base portion
204m to the head portion 204a via the connection portion 204n,
thus penetrating the leg portion in the radial direction.
An engaging portion 204d protruding outwardly in the
radial direction is formed on the outside surface of the head
portion 204a. The engaging portion 204d engages with a rim
208a of a concave portion 208b. The inside surface 204e is so
arranged as to be located slightly inside the outer diameter
of the ring 202, so that the ring 202 abuts the inside surface
204e with the aid of the resilience of the ring, whereby to
press the engaging portion 204d outwardly in the radial
directi~n, i.e., the engaging portion is pressed toward the
rim 208a of the wheel 208. The top end pcrtion of the slit
204c is located at a circumferential central portion of the
- 21 - 1323331
head portion 204a of the holding claw 204. The protrusion
204f is located at a position adjacent the top end of the
slit 204c. Furthermore, the wire-ring-engaging surface 204g
of the protrusion 204f extends to the top end surface of the
S slit 204c. The protrusion 204f is so formed as to have a cross-
sectional shape approximating a triangle protruding inwardly
in the radial direction. The inside tip portion in the
radial direction of the protrusion 204f protrudes inwardly
over the ring 202 which abuts the inside surface 204e. The
surface 204g of the protrusion 204f facing the main body 205
is formed as an incline that slants with respect to the main
body 205 f~om the radially outside portion to the inside
portion, the angle formed by the inside surface 204e of the
head portion 204a and the surface 204g being less than 90
degrees, thereby preventing the ring 202 engaged with the
protrusion 204f from being removed from the protrusion 204f
in the upward direction shown in Fig. 29. In addition,
concave portions 204h are formed on the head portion 204a
between the engaging portions 204d to prevent a sink when
injection-molding the holding claw.
The holding claw 204 is formed by means of the
following processes: As shown in Fig. 31, the holding claw
204 is injection-molded by the outer mold 207 which can move
outwardly in the radial direction (in the ~rawing; to the
left?, and the inner mold 209 which can move in the direction
of the thickness of the wheel cover main body. The outer
mold 207 molds the outside surface of each holding claw 204,
i.e., the engaging portions 204d, the outside surface and
side surface 204j having the curved surface 204i of the leg
portion 204b, the concave portions 204h, as well as the slit
204c of each holding claw 204 and engaging surface 204g of
the protrusion 204f, and so on. The inner mold 209 molds
the inside surface 204e in the radial direction of each
holding claw 204, the protrusion 204f, and so on. The holding
claw 204 is, therefore, molded by the combination of both
molds 207 and 209 using a conventional injection-molding
, .,
1323391
- 22 -
method.
Further, first support members 203 are integrally
formed at constant intervals on the wheel cover main body 205
between the neighboring holding claws 204. The second support
member 206 is formed at constant intervals on the inside
surface of each holding claw 204. Each first support member
203 is made as an approximately rectangular plate that is
positioned on the wheel cover in the circumferential direction
in such a way that the plate surface extends in the radial
direction and has enough width and thickness to prevent itself
from being deformed when subjected to the radial force and
from being excessively bent when subjected to the
circumferential force. At the top end surface of each first
support member 203 there is formed a groove 203a which controls
the radial movement of the ring 202, thereby preventing the
ring 202 from moving excessively in the radial direction in
conjunction with the holding claw 204. Also, second support
member 206 includes a central wall 206a and a pair of side
walls 206b at both ends of a central wall 206a. The central
wall 206a is arranged approximately in parallel with the
inside surface 204e of each holding claw 204 so as to face the
slit 204c of each holding claw 204. When each holding claw
204 is bent excessively inwardly in the radial direction, the
inside surface 204e of each holding claw 204 contacts the
central wall 206a of the second support member 206, thereby
preventing the holding claw 204 from being excessively bent.
According to the construction described above, as
shown in Fig. 29, the ring 202 is allowed to directly abut on
the inside surface 204e of the head portion 204b and to
engage with theprotrusion 204f. The ring 202 is provided from
the rear surface and over the protrusion 204f. The ring 202 is
inserted into and supported by the groove 203a of the first
support member 203 in such a manner as to be movable in the
radial direction, When the ring 202 is abutted against the
inside surface 204e of each holding claw 204, the ring 202 is
slightly deformed; the resilient force generated by this
1323391
- 23 -
bending motion acts on the inside surface 204e of each holding
claw 204, and slightly presses each holding claw 204 outwardly
in the radial direction. Moreover, as shown in Fig. 29, when
the holding claw 204 of the wheel cover 201, wherein the ring
202 is fitted, are pressed into contact with the rim 208a of
the wheel 208 and the holding claws are inwardly bent in the
radial direction, the ring 202 abutted the inside surface 204e
of the holding claw 204 is bent inwardly with the holding claws
204 in the radial direction. Subsequently, the wheel cover 201
is gradually fitted in the wheel 208, then the ring 202,
- together with each holding claw 204 of the wheel cover 201, is
fitted in the wheel 208, with the ring 202 being inwardly bent
in the radial direction. Thus the wheel cover 201 is completely
fitted in the wheel 208, the claw 204d being engaged with
i5 the concave portion 208b of the rim 208a of the wheel 208 with
the aid of the combined resilient force exerted by the wire
202 and the holding claw itself, the wheel cover 201 thus being
securely held by the wheel 208. The wheel cover 201 can be
removed from the wheel 208 by releasing the engagement of some
holding claws 204 with the rim 208a.
According to Embodiment 3 described above, the wheel
cover is so constructed that the slit 204c is formed in the
leg portion 204b of each holding claw, wherein the outer mold
207 is i~serted in the radial direction through the slit 204c
so that the surface 204g is so formed that the top end surface
of the slit 204c becomes a part of the wire-ring-engagement
surface. Consequently, even if the inner mold 209 is so
designed as to be drafted in the direction of the thickness of
the wheel cover main body 205, the angle formed by the surface
204g and the inside surface 204e of the head portion can be
made to less than 90 degrees. The leg portion 204b can be
formed in such a manner that its width increases from the
connection portion 204n toward the base portion 4m, and the
leg portion 204b can be provided with sufficient strength,
whereby the stress acting on the holding claw 204 can be
effectively prevented from increasing excessively. Also,
- 24 _ 1 32 3 3~ 1
the protrusion 204f having engaging surface 204g for engaging
the ring 202 at both ends of the head portion 204a, is
eliminated and the protrusion 204f is formed at the inter-
mediate portion of both ends. Therefore, the leg portion 204b
can be so formed as to have the desired width without being
restricted by the protrusion 204f. The ring 202 can be
securely engaged with the engaging surface 204g. Further, the
connection portion of each side surface 204j and wheel cover
main body 205 can be made in the form of the curved surface
204i in the base portion 204m of the leg portion 204b, whereby
the stress concentration on the foregoing connection portion
can be effectively prevented.
The configuration of the foregoing second support
member 6 is not limited to a U-shaped wall, but any other
configuration, for example, a support member 206' which is
formed from a parallelepiped body, may be utilized, as shown
in Fig. 32.
Embodiment 4
Embodiment 1 has the disadvantage that, when the
wheel cover is to be fixed to the rim of the wheel and when
the head portion of each holding claw contacts the wheel rim,
the head portion cannot be accidentally guided along the rim
toward the center of the wheel, which could be reversely
guided in the outward direction, causing the head portion to
bend in the outward direction of the wheel cover main body
and not to engage the concave portion of the rim, thus making
it difficult to insert the wheel cover onto the wheel, and,
in an extreme case, with the result that the holding claw
suffers plastic deformation and cannot be forcibly pressed
against the rim, which would make it difficult to attach and
hold the wheel cover onto the wheel. The inventors of the
present invention have analyzed the cause of this problem as
described hereinbelow according to Figs. 33 and 34. It is to
be noted that Figs. 33 and 34 shows substantially the same
holding claw as that of Embodiment 1.
13233~1
- 25 -
When each holding claw 4 is, as shown in Fig. 33(a),
contacted ~y the rim 8a of the wheel 8, a reaction force P
from the wheel acts on the holding claw 4 at a contact point.
This reaction force P can be divided into a component force Ps
acting in the axial direction of the leg portion 4b of the
holding claw 4 and a component force Pr acting in the direction
orthogonally intersecting such axial direction, i.e., the
radial direction of the wheel cover main body. A moment
diagram in terms of each component force is shown in Figs.
33(b) and (c), where the length of the holding claw 304
extending from the rear surface of the wheel cover main body
is expressed as L, and the distance from the contact point
between the holding claw 4 and the rim 8a to the inside
surface of the leg portion 4a for the holding claw 4 is
indicated as Q. As illustrated in Fig. 33 (d), with the sum
of the moments resulting from the above-described component
forces, the moment Ps-Q, which has a tendency to bend the
holding claw 4 in the outward direction, acts on both the
head portion 4a and a portion, close to the head portion, of
the leg portion 4b, while the moment Pr-L, which has a tendency
to bend the holding claw 4 in the inward direction, acts at a
portion, on the wheel cover main body, of the leg portion 4b
of the holding claw 4. It is conceivable from Fig.33 that the
maximum moment acts on the head portion of the holding claw 4.
However, the head portion 4a is free from deformation due to
the high geometrical moment of inertia thereof. Rather, at a
constricted portion of the holding claw 4, i.e., at a portion,
close to the head portion, of the leg portion 4b, the stress
is a maximum and the deformation tends to occur. In actuality,
the compressed force resulting from the axial component force
Ps acts on the holding claw 4 in addition to the foregoing
moment; thus the holding claw 4 is more liable to be
subjected to so~called neck-breakage.
Referring to Fig. 34, to permit the rim 8a of the
wheel 8 to securely facilitate guiding along a guide portion
4Q on the top surface of the head portion 4a for the holding
13233~1
- 26 -
claw 4, it is necessary to enlarge as much as possible the
radial dimension Ql of the guide portion 4Q. At the same time,
since the slope on the internal surface of the head portion for
the holding claw 4 is, as it were, an undercut against the
mold draw direction (in the direction of the arrow A as
indicated in Fig. 34), it is necessary to minimize the radial
dimension Q2 of the undercut portion so as to reduce the amount
of forced draw, with the result that the dimension between the
internal surface of the leg portion 4b and the external surface
of-the head portion is large and is expressed as Q3 = Ql ~ Q2
Consequently , when the head portion 4a of the holding claw 4
is to be bent in the radially inward direction, the dimension
Q between the contact point where the rim 8a of the wheel 8
contacts the head portion 4a of the holding claw 4, and the
internal surface of the leg portion of the holding claw 4
becomes large, attaining the size of the foregoing dimension
Q3. Consequently, the moment Ps-Q increases, causing the
head portion of the holding claw 4 to bend in the radially
outward direction, hampering smooth sliding of the head portion
4a along the rim 8a toward the center of the wheel, thereby
making it difficult to bend the holding claw 4 along the rim
in the radially inward direction, which could conceivably
make it difficult to fit the wheel cover onto the wheel.
The inventors of the present invention have
discovered that, in order to prevent the head portion of such
holding claw from bending in the radially outward direction
of the main body, the external surface of a portion, close to
the head portion, of the leg portion, at which the maximum
stress occurs, should be formed by a thick wall to increase
the geometrical moment of inertia at said portion, thereby
preventing extreme lowering of the geometrical moment of
inertia at said portion and thus effectively preventing the
head portion from bending in the outward direction.
In view of this problem, the object of Embodiment 4
is to provide a wheel cover that allows the holding claws to
securely bend in the radially inward direction and that can be
~ 27 - 13233~1
easily attached to the wheel.
Referrinq to Fig. 35 - Fig. 39, the Embodiment 4
is described below:
A wheel cover 301 according to the present embodiment,
as illustrated in Fig. 35 and Fig. 36, is so constructed that
a plurality of holding claws 304 is integrally formed on the
rear surface of an almost circular wheel co-~er main body 305
made of synthetic resin, and a circular,resilient metallic
wire ring 302 for reinforcement is held by each holding claw
304, wherein, when the wheel cover 301 is removably inserted
onto a wheel 308, a head portion 304a of each said holding
claw 304 is forcibly pressed against a rim 308a of the wheel
308 by the resilience of both the wire ring ~02 and each said
holding claw 304.
Each holding claw 304 mainly comprises a leg portion
304b protruding from the rear surface of the main cover 305
and a head portion 304a formed at the tip of said leg portion
304b. There is provided an engaging portion 304d mounted -
on the radial outside of the head portion 304a and fitted into
20 a concave portion 308b of the rim 308a of the wheel 308.
There is provided a protrusion 304f in the shape of triangle
in section, which protrudes from each end in the circumferential
direction of the head portion 304a. Each protrusion 304f
protrudes in the radial direction more inwardly than an internal
surface 304e of the head 304a, and which abuts on the internal
surface 304e, so that the ring 302 is securely held by each
protrusion 304f and is prevented from being removed toward the
lower side in Fig. 36. The bottom surface of each protrusion
304f is formed into a slope 304g in such a way that the bottom
30 surface approaches the wheel cover main body 305 as it moves
in the direction from the outside radius to the inside radius,
and the angle between the surface 304e and the slope 304g is
less than 90 degrees. Further, the leg portion 304b is
flexible so that the wire ring can be fitted into the holding
35 claws 304 and be engaged with the protrusions 304f to be held.
- 28 - 1323391
Subsequently, the wheel cover 301 can be easily attached to
the wheel 308, since the leg portion 304b can be bent inwardly.
A thick reinforcement portion 304c is integrally
formed, projecting from a portion close to the head portion
of this leg portion, i.e., the external surface of the portion
where the foregoing moment Ps.Q acting on the holding claw
304 becomes high due to the reaction force P generated from the
rim 308a when the head portion 304a bends by abutting on the
rim 308a of the wheel 308. The side configuration of the
reinforcement portion 304c is formed in a triangular shape,
in such a way that the side of the reinforcement portion 304c
is thin as it moves in the direction from the vicinity of the
head portion toward the wheel cover main body. This reinforce-
ment portion 304c effectively prevents extreme lowering of the
geometrical moment of inertia at a portion where the moment
Ps.Q of the leg portion 304b is high. This reinforcement
portion 304c, as illustrated in Fig. 37, may be formed into
a shape with two convex portions 309 and 309 at the corres-
ponding area of the leg portion 304b, one convex portion 310
as shown in Fig. 38, or a convex portion 311 protruding from
the entire corresponding area as shown in Fig. 39. That is,
the configuration of the reinforcement portion 304c can be
arbitrarily chosen, provided that the above-described
measures are attainable. The reinforcement portion 304c is
not necessarily in the vicinity of the wheel cover main body,
since the moment is low close to the wheel cover main body,
thus permitting a low geometrical moment of inertia. Concave
portions 304h are formed in the engaging portion 304d so as to
prevent a sink when molding the holding claw.
In Fig. 35, numeral 303 shows a support member. The
ring 302 is received by a groove or recess on the top end
surface thereof so that radial movement of the ring 302 is
controlled.
According to this construction, as illustrated in
35 Fig. 36, the ring 302 is crossed over the projections 304f of
each holding claw 304, with each holding claw 304 being bent,
. : i
1323391
- 29 -
and the ring 302, held by both projections 304f of each
holding claw 304, is contacted by the internal surface 304e
of the head portion 304a. At the same time, the ring 302 is
inserted into the groove of each support member 303, thereby
being allowed to freely make a radial movement within a fixed
range when supported thereon. The ring 302, when remaining
contacted by the internal surface 304e of each holding claw
304, bends slightly , causing the resilience corresponding to
the magnitude of the bending to be applied to each holding
claw 304; thus each holding claw 304 is slightly pushed onto
the outside radius. When the wheel cover 301 is to be
attached to the wheel 308, the holding claws 304, which are
part of the wheel cover 301, begin to be successively contacted
by the rim 308b of the wheel 308. When the head portion 304a
of each holding claw 304 abuts the rim 308a of the wheel 308,
the reinforcement portion 304c controls the radially outward
bending of the head portion 304a of the holding claw 304,
causing this head portion 304a to bend in the radially inward
direction, sliding along the rim 308a and engaging the
concave portion 308b of the rim 308a. Each holding claw 304
is forcibly pressed against the wheel 308; thus the wheel cover
301 together with the holding claw 304 is finally mounted on
the wheel 308 with the ring 302 being bent. Under this
condition, a force, i.e., the sum of the resiliences of the
holding claw itself and the ring 302, acts on each holding
claw 304, whereby the engaging portion 304d of the head portion
304a for each holding claw 304 engages the concave portion 308b
of the rim 308a for the wheel 308; thus the wheel cover 301
is securely fixed to the wheel 308. When the wheel cover 301
is to be removed from the wheel 308, by forcibly pressing the
holding claw 304 against the rim 308a, the wheel 308 is
released, and the wheel cover 301 can be removed in a manner
similar to that of a conventional wheel cover.
According to this embodiment, when the head portion
304a of each holding claw 304 abuts the rim 308a and is thus
subjected to the reaction force therefrom, the head portion
1323391
- 30 -
304a has a tendency to bend onto the outside radius of the
wheel cover main body 305. However, the reinforcement portion
304c controls the outward bending of this head portion 304a,
since the reinforcing portion 304c is formed close to the head
of the leg portion 304b; thus, the head portion 304a bends
inwardly, guided to slide along the rim, and engages the
inside of the concave portion 308b. Consequently, at a
portion of the holding claw 304 where the stress is high, i.e.,
where the moment shown in the moment diagram is high, the
geometrical moment of inertia increases with the aid of the
reinforcement portion 304c. Furthermore, at a portion of the
holding claw 304 close to the wheel cover main body, where the
moment is low, the geometrical moment of inertia decreases due
to the absence of the reinforcement portion 304c, whereby the
internal stress is uniformly spread throughout the entire leg
portion, thus effectively preventing local deformation or
bending, and consequently the wheel cover 301 can be easily
attached to the wheel 308. That is, a guiding portion 304i
resting against the rim 308a can be securely maintained in
each holding claw 304, with the result that the head portion
304a has an effective guiding ability, thereby allowing easy
attachment of the wheel cover 301 to the wheel 308. Further,
at the time of molding each holding claw 304, it is possible to
minimize the amount of undercut against the mold draw direction
of the internal surface 304e, which allows the mold draw to be
a forced draw, and hence a low cost for the mold.
.
