Electrical connectors – With relatively guided members and intermediate pliable... – Relatively movable about axis
Reexamination Certificate
1998-07-10
2001-10-16
Paumen, Gary (Department: 2833)
Electrical connectors
With relatively guided members and intermediate pliable...
Relatively movable about axis
Reexamination Certificate
active
06302716
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rotatable connector mounted in a steering system of an automobile for use as an electrical connecting means of an air bag system and, more particularly, to a rotatable connector in which flat cables are reversely wound through a turned-back portion within a housing section defined between a stationary housing and a movable housing.
2. Description of the Prior Art
The rotatable connector has flat cables which are housed and wound between a stationary housing and a movable housing rotatably mounted on the stationary housing, and is used as an electrical connecting means of an air bag inflator or other built in a steering wheel which is mounted on a steering system of an automobile and rotated by a limited number. The flat cable is a strip-like body having a plurality of conductors. There have been known two types of flat cables: one wound in a spiral form and the other turned back halfway to an opposite direction; and the latter, or the turned-back type, can be made substantially shorter than the former.
In the turned-back rotatable connector, a single flat cable is usually employed. However, when the number of conductors increases with adoption of multiple circuits, the flat cable increases in width with the number of the conductors, thereby preventing a decrease in the thickness of the whole body of the rotatable connector. According to the rotatable connector disclosed in the specification of U.S. Pat. No. 3,763,455, however, the conductors are divided into the two flat cables to thereby meet the adoption of the multiple circuits.
FIG. 6
is a plan view schematically showing the constitution of a cable reel disclosed in the above-described patent specification. As shown in
FIG. 6
, a movable housing
101
having an inner cylindrical portion is rotatably connected to a stationary housing
100
having an outer cylindrical portion. A first flat cable
103
and a second flat cable
104
are inserted in an annular housing section
102
defined between the stationary housing
100
and the movable housing
101
. These flat cables
103
and
104
are arranged, in opposite winding directions, in the outer cylindrical portion of the stationary housing
100
and in the inner cylindrical portion of the movable housing
101
in the housing section
102
. U-shaped turned-back portions
103
a
and
104
a
are formed in a position where the winding direction is changed. The inner ends of both the flat cables
103
and
104
are connected to cable exit portions
107
and
108
disposed adjacently to the inner cylindrical portion of the movable housing
101
, and led out of the movable housing
101
through the cable exit portions
107
and
108
. On the other hand, the outer ends of both the flat cables
103
and
104
are connected to cable exit portions
109
and
110
located adjacently to the outer cylindrical portion of the stationary housing
100
, being let out of the stationary housing
100
through the cable exit portions
109
and
110
. Furthermore, in the housing section
102
are arranged a plurality of roller groups
105
and
106
along the circumferential direction thereof. The turned-back portion
103
a
of the first flat cable
103
is coiled around one of rollers in the roller group
105
, while the turned-back portion
104
a
of the second flat cable
104
is coiled around one of rollers in the other roller group
106
.
In the rotatable connector thus constituted, when for instance the movable housing
101
is turned clockwise in
FIG. 6
, the turned-back portions
103
a
and
104
a
of the flat cables
103
and
104
move clockwise within the housing section
102
by a less amount of rotation than the movable housing
101
, thus winding the flat cables
103
and
104
more on the inner cylindrical portion side of the movable housing
101
. Conversely, when the movable housing
101
is turned counterclockwise in
FIG. 6
, the turned-back portions
103
a
and
104
a
of the flat cables
103
and
104
move in the same direction by a less amount of rotation than the movable housing
101
; that is, the flat cables
103
and
104
are unwound, thus being wound much on the outer cylindrical portion side of the stationary housing
100
. The rollers
105
and
106
are moved in the same direction by a force from the turned-back portions
103
a
and
104
a
of the flat cables
103
and
104
at the time of winding and unwinding.
In the prior art rotatable connector described above the radial deformation of the flat cables
103
and
104
is restricted by a plurality of roller groups
105
and
106
, and therefore the flat cables
103
and
104
can be smoothly moved in the circumferential direction of the housing section
102
. However, since the plurality of roller groups
105
and
106
are separately arranged within the housing section
102
, the roller groups
105
and
106
hit against each other, producing a sound of collision, when the rotatable connector vibrates, resulting in lowered assembling operation performance.
It is, therefore, conceivable to adopt such a structure that a moving body
111
having at least a couple of openings
111
a
and
111
b
is rotatably disposed inside the housing section
102
in place of the use of the mutually independent roller groups
105
and
106
as shown in
FIG. 7
, and the turned-back portions
103
a
and
104
a
of the flat cables
103
and
104
are arranged through the openings
111
a
and
111
b.
The moving body
111
is comprised of a ring-like rotary disk
112
and a plurality of roller groups
113
axially supported on the rotary disk
112
, and the openings
111
a
and
111
b
are formed, equally spaced between these roller groups
113
. Therefore, when the moving body
111
having the openings
111
a
and
111
b
is used, the rotary disk
112
and the roller groups
113
can be handled as one body and can prevent the collision of the roller groups
113
. The aforesaid problem inherent to the prior art rotatable connector can be solved, but a later-described new problem will arise.
That is, in the above-described rotatable connector, let D be the diameter of the inner cylindrical portion of the movable housing
101
and t be the thickness of the flat cables
103
and
104
, and the winding diameter of the first flat cable
103
directly wound on the inner cylindrical portion is D and the winding diameter of the second flat cable
104
wound on the inner cylindrical portion via about one turn of the first flat cable
103
becomes (D+2t). In this case, the flat cables
103
and
104
differ in winding diameter. Therefore, when the movable housing
101
is turned, the length of the flat cables
103
and
104
wound on the inner cylindrical portion, or the length of these flat cables unwound from the inner cylindrical portion, varies, with the result that the turned-back portion
104
a
of the second flat cable
104
having a large winding diameter moves faster than the turned-back portion
103
a
of the first flat cable
103
having a small winding diameter. Consequently, for instance when the flat cables
103
and
104
are fed out from the inner cylindrical portion and wound on the outer cylindrical portion as illustrated, the turned-back portion
104
a
of the second flat cable
104
contacts the roller
113
which is disposed at the end of the opening
111
b.
In this case, however, the turned-back portion
103
a
of the first flat cable
103
which moves at a slow speed moves only in the opening
111
a
and does not contact the roller
113
Therefore there arises such a problem that the moving body
111
cannot smoothly be moved by the force from the turned-back portions
103
a
and
104
a.
The present invention, therefore, has an object to provide a rotatable connector in which a moving body disposed in a housing section has a plurality of openings through which turned-back portions of a plurality of flat cables pass, and at least one of the openings is set less in width along the peripheral direction than the other. If the o
Bannai Hiroyuki
Ito Takehiko
Matsumoto Mitsunori
Matsuzaki Nobuo
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Paumen Gary
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