Electrical connectors – With relatively guided members and intermediate pliable... – Relatively movable about axis
Reexamination Certificate
2000-06-23
2002-03-12
Sircus, Brian (Department: 2839)
Electrical connectors
With relatively guided members and intermediate pliable...
Relatively movable about axis
Reexamination Certificate
active
06354854
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicle-mounted rotary connector mounted to a steering system of a motor vehicle to be used as an electrical connection means for an air bag system or the like. More particularly, the invention relates to a vehicle-mounted rotary connector in which plural flexible cables are accommodated in a cable-accommodating space and the winding direction of the flexible cables is reversed in the cable accommodating space.
2. Description of the Related Art
A vehicle-mounted rotary connector is incorporated in a steering system of a motor vehicle to be used as an electrical connection means for an air bag circuit, a horn circuit, and other switch circuits fitting in a steering wheel, and is basically composed of a pair of a fixed housing and a movable housing which are coaxially disposed and are rotatably connected to each other, and a flexible cable accommodated in such a manner that it can be wound up and unwound in a ring-shaped cable-accommodating space formed between the pair of housings. The flexible cable carries plural electrically independent conductors between two insulating base films and is formed in a belt-like shape.
Along with the recent increasing trends toward fitting circuits in steering wheels, an increase in the number of conductors carried by the flexible cable, that is, an increase in the number of circuits, and a reduction in the external dimensions are demanded.
Hitherto, this type of rotary connector has been proposed, as disclosed in, for example, U.S. Pat. No. 5,865,634 in which plural flexible cables are accommodated in a cable-accommodating space, and the winding direction of the flexible cables is reversed halfway. The accommodation of the plural flexible cables in the cable-accommodating space can respond to the demand for increasing the number of circuits because the number of conductors capable of being carried by the flexible cables can be increased as compared to the accommodation of only one flexible cable. In addition, the halfway reversal of the winding direction of the flexible cables can shorten the necessary length of the flexible cable to about one-half as compared to a case in which the flexible cables are not reversed halfway. Therefore, the number of windings of the flexible cables can be decreased, and the external dimension of the rotary connector can be reduced.
A rotating member (called a moving member) is accommodated in the cable-accommodating space, and the flexible cable is wound in a U-shape around a roller fitted on the moving member, whereby the winding direction of the flexible cable is reversed.
FIG. 5
shows a construction of the rotary connector disclosed in U.S. Pat. No. 5,865,634. Referring to
FIG. 5
, there are provided a fixed housing
101
, a movable housing
102
, a ring-shaped cable-accommodating space formed between the pair of housings
101
and
102
, a moving member
104
rotatably accommodated in the space-accommodating space
103
, first and second rollers
105
and
106
rotatably fitted on the moving member
104
, first and second openings
107
and
108
formed in the moving member
104
for passing flexible cables therethrough, first and second flexible cables
109
and
110
, and connectors
111
and
112
connected to both ends of the flexible cables. In this specification, in order to facilitate comparison of the present invention with the above conventional example, components in the conventional example are renamed to correspond to the components shown in FIG.
5
.
The flexible cables
109
and
110
are double-wound with the first flexible cable
109
wound on the inner peripheral side and the second flexible cable
110
wound on the outer peripheral side, and are accommodated in the cable-accommodating space
103
. The connectors
111
and
112
connected to both ends of the flexible cables
109
and
110
are fixed to the fixed housing
101
and the movable housing
102
, respectively, and are connected to external circuits, such as an air bag circuit and the like. The first flexible cable
109
passes through the first opening
107
during its winding to be wound around the first roller
105
in a U-shape, whereby the winding direction is reversed 180 degrees. On the other hand, the second flexible cable
110
passes through the second opening
108
during its winding to be wound around the second roller
106
in a U-shape, whereby the winding direction is reversed 180 degrees.
In the rotary connector, when the movable housing
102
is rotated counterclockwise in relation to the fixed housing
101
, the flexible cables
109
and
110
are wound up around the movable housing
102
, reversed sections
109
a
and
110
a
come into close contact with the peripheral surfaces of the first and second rollers
105
and
106
, so that the first and second rollers
105
and
106
are rotated clockwise and counterclockwise, respectively, by tensile forces of the flexible cables
109
and
110
, and the moving member
104
is rotated counterclockwise. Conversely, when the movable housing
102
is rotated clockwise in relation to the fixed housing
101
, the flexible cables
109
and
110
are unwound from the movable housing
102
, and the reversed sections
109
a
and
110
a
come into close contact with side face portions of the first and second openings
107
and
108
, so that the moving member
104
is rotated counterclockwise by pressing forces of the flexible cables
109
and
110
. This can maintain the continuity between the flexible cables
109
and
110
during the rotation of the movable housing
102
.
The rotary connector constructed as described above, however, does not take this into consideration at all because of double winding of the flexible cables
109
and
110
, the difference between the winding amount of the flexible cables
109
and
110
around the movable housing
102
and the unwinding amount of the flexible cables
109
and
110
from the movable housing
102
is generated when the movable housing
102
is rotated, and includes the following inconveniences.
That is, when the movable housing
102
is rotated counterclockwise to gradually wind up the double-wound flexible cables
109
and
110
around the movable housing
102
, since the winding speed of the second flexible cable
110
disposed and wound on the outer peripheral side is faster than that of the first flexible cable
110
disposed and wound on the inner peripheral side, and the first and second openings
107
and
108
of the conventional rotary connector are formed to have the same widths w
1
and w
2
, the first flexible cable
109
does not abut against the first roller
105
even if the second flexible cable
110
abuts against the second roller
106
in accordance with the rotation of the movable housing
102
. In addition, since the moving speed of the reversed section
110
a
in the circumferential direction is faster than the moving speed of the reversed section
109
a
in the circumferential direction, the reversed section
109
a
is brought into abutment with a wall opposing the roller
105
. In this state, the moving member
104
and the reversed section
109
a
push strongly against each other, whereby the rotation of the moving member
104
and the movable housing
102
is prevented.
This also applies to a case where the movable housing
102
is rotated clockwise to unwind the double-wound flexible cables
109
and
110
from the movable housing
102
. That is, since the unwinding speed of the second movable cable
110
disposed and wound on the outer peripheral side is faster than that of the first flexible cable
109
disposed and wound on the inner peripheral side, and the first and second openings
107
and
108
of the conventional rotary connector are formed to have the same widths w
1
and w
2
, the second flexible cable
110
abuts against the side face portion of the second opening
108
prior to the first flexible cable
109
in accordance with the rotation of the movable housing
102
. In addition, since the movin
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Duverne J. F.
Sircus Brian
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