Rotary connector

Details Rotary connector Rotary connector

2000-01-19

2001-07-24

Paumen, Gary F. (Department: 2833)

Electrical connectors

With relatively guided members and intermediate pliable...

Relatively movable about axis

C439S015000

Reexamination Certificate

active

06264487

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a rotary connector used for a steering device for a motor vehicle or the like. More particularly, the invention relates to a rotary connector whose outer case and inner case which is rotatable relatively to the outer case are electrically connected by using a flexible flat cable.
BACKGROUND OF THE INVENTION
In general, in a conventional rotary connector, a flexible flat cable shares high percentage of the total cost of the rotary connector. A proposal disclosed in the Japanese Non-Examined Patent Publication H4-310445 is an example for saving the cost by decreasing the length of the flexible flat cable.
Hereinafter the conventional rotary connector is described referring to FIG.
14
through FIG.
16
.
FIG. 14
is a cross sectional plan view showing the conventional rotary connector,
FIG. 15
is a cross sectional side view showing the main portion of the same, and
FIG. 16
is an exploded view showing the conventional rotary connector.
As shown in the illustrations, at the inner side of an annular outer case
510
, an inner case
520
is disposed in such a manner as to be rotatable relatively to the outer case
510
. The inner case
520
comprises a cylindrical portion
522
and a cover portion
521
which covers the upper side of an annular space
540
formed with the inner wall
511
of the annular outer case
510
and the outer wall of the cylindrical portion
522
of the inner case
520
. A lower-side-cover
530
is fixed to the lower side of the annular outer case
510
, and covers the lower side of the annular space
540
.
In the annular space
540
, a flexible flat cable
550
is disposed. The respective ends (
551
,
552
) of the cable
550
are respectively fixed to the outer case
510
and to the inner case
520
, by which the outer case
510
and the inner case
520
are electrically connected as well. The outer case
510
and the inner case
520
are respectively further electrically connected to outer electrical circuits. In the annular space
540
, the cable
550
is wound along the inner wall
511
of the outer case
510
in a first direction, and along the outer wall of the cylindrical portion
552
of the inner case
520
in a second direction which is opposite to the first direction via a U-shaped reversed-portion
553
.
In the annular space
540
, a plurality of rollers
570
, which are connected by a connecting member
560
along the annular space
540
, are disposed. The rollers
570
respectively rotate, and, guide and regulate the cable
550
wound along the annular space
540
. Rollers
571
and
572
disposed at the respective end portions (i.e. cut-portion
561
) of the connecting member
560
guide the cable
550
which passes through the cut-portion
561
to be reversed along the rollers
571
and
572
.
In the above structure, when the inner case
520
is counterclockwise rotated, the cable
550
is wound off from the side of the cylindrical portion
522
of the inner case
520
, and the reversed-portion
553
of the cable
550
presses the roller
571
, whereby the connecting member
560
is counterclockwise rotated and the cable
550
becomes the state of wound-off (i.e., the dimension of the cable
550
becomes longer than before at the side of the inner wall
511
of the outer case
510
).
On the other hand, when the inner case
520
is clockwise rotated, the cable
550
is wound up toward the side of the cylindrical portion
522
of the inner case
520
and presses the roller
572
, whereby the connecting member
560
is rotated clockwise and the cable
550
becomes the state of wound-up (i.e., the dimension of the cable
550
becomes longer than before at the side of the cylindrical portion
522
of the inner case
520
).
However, in the above conventional structure, predetermined clearances are formed between the rollers (
570
,
571
,
572
) and the outer case
510
, and, between the rollers and the inner case
520
, also between the connecting member
560
and the outer case
510
, also between the connecting member
560
and the inner case
520
, for enabling the winding of the cable
550
and for enabling the rotation of the rollers. Also the mass of the rollers are large. Therefore, when a vibration is applied to the rotary connector during driving a motor vehicle for instance, an audible noise caused by the each-other's bumps of the component parts of the rotary connector occurs.
Also, when the inner case
520
is rotated, the connecting member
560
is moved along the rotating direction of the inner case
520
in the annular space
540
. In this case, the reversed-portion
553
of the cable
550
presses the roller (
571
,
572
), which causes the damage of the cable
550
due to the stress applied to the flat cable
550
.
SUMMARY OF THE INVENTION
The present invention addresses the problems in the conventional rotary connector and aims to provide a highly reliable low cost rotary connector, in which a noise caused by the each-other's bumps of the component parts (i.e., rollers, cases and the like) of a rotary connector is suppressed and stress applied to a flat cable is greatly decreased.
For realizing the above aim, the rotary connector of the present invention comprises:
(a) an annular outer case,
(b) an inner case disposed at the inner side of the annular outer case, wherein the inner case comprises a cylindrical portion and a cover portion which covers the upper side of the annular space formed with the outer annular case and the cylindrical portion of the inner case,
(c) a lower-side-cover which is fixed to the outer annular case and covers the lower side of the annular space,
(d) a flexible flat cable which is disposed in the annular space in such a manner as to be wound along the inner wall of the outer annular case in a first direction, and along the outer wall of the cylindrical portion of the inner case in a second direction which is opposite to the first direction via the reversed-portion of the cable,
(e) a guide ring which has a cut-portion where the reversed-portion of the cable passes through, wherein the guide ring is disposed in the annular space in such a manner as to be rotated along the annular space in the state that the guide ring elastically contacts with the lower side of the cover portion of the inner case, and
(f) a plurality of cylindrical rollers, wherein the intermediate supporting portion of each of the rollers is rotatably supported by the guide ring in the state that the rotation axis of each roller slants, and the lower portion of the outer end-side and the upper portion of the inner end-side of each roller respectively contact with the cable, also the circumference-side of each roller elastically contacts with the upper side of the lower-side-cover.
The above structure realizes a highly reliable low cost rotary connector in which a noise caused by the each-other's bumps of the components parts of the rotary connector is suppressed and stress applied to the cable is greatly decreased.


REFERENCES:
patent: 5046951 (1991-09-01), Suzuki
patent: 5219460 (1993-06-01), Kato et al.
patent: 5224871 (1993-07-01), Ida et al.
patent: 5314344 (1994-05-01), Ida et al.
patent: 5669777 (1997-09-01), Matsumoto et al.
patent: 5865634 (1999-02-01), Best
patent: 5890921 (1999-04-01), Kuroda et al.
patent: 5980286 (1999-04-01), Best et al.
patent: 4419077 A1 (1994-12-01), None
patent: 4422788 A1 (1995-01-01), None
patent: 0770521 A1 (1997-05-01), None
patent: 4-310445 (1992-11-01), None

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