Rotation connection unit

Details Rotation connection unit Rotation connection unit

2001-07-16

2003-01-14

Pauman, Gary (Department: 2833)

Electrical connectors

With relatively guided members and intermediate pliable...

Relatively movable about axis

Reexamination Certificate

active

06506066

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates to a rotation connection unit, for example, being built in a steering system of an automobile for use as means for connecting circuit wiring of a steering wheel side (rotation side) and a body side (fixed side).
2. Related Arts
Hitherto, as this kind of rotation connection unit, a swirl type wherein a belt-like cable for conduction, which normally is called a flat cable and will be hereinafter called simply cable, is wound like a swirl in a cable housing space and an inversion type wherein the winding direction of the cable is inverted at an intermediate point have been known.
An inversion-type rotation connection unit taking an inversion-type multiple-winding structure of housing two or more cables in response to an increase in the number of circuits to be connected is also known.
FIG. 8
is a sectional view of a rotation connection unit in a related art and
FIG. 9
is a front view of only cables in the rotation connection unit in the related art. Here, a double-winding structure using two flat cables is taken as an example and the case where the rotation connection unit is built in a steering system of an automobile is illustrated.
In the figures, numeral
101
denotes a case as a cylindrical outer member fixed to the body side of the automobile and numeral
102
denotes a rotor as an inner member rotated in one piece with a steering shaft. A cable housing space
103
is formed between the case
101
and the rotor
102
. Two cables (a first cable and a second cable)
104
and
105
are housed in the cable housing space
103
in such a manner that they are wound and that the cable winding direction is inverted at an intermediate point.
A guide ring
106
for movably guiding both the cables
104
and
105
has guide grooves
107
and
108
at two parts in a circumferential direction (usually, symmetrical two parts spaced
180
degrees from each other as shown in the figure). An inversion part
104
a
of the first cable
104
is passed through one guide groove
107
(first guide groove) and an inversion part
105
a
of the second cable
105
is passed through the other guide groove
108
(second guide groove).
Both the cables
104
and
105
have inner peripheral terminals fixed to the rotor
102
by inner peripheral terminal members
109
and
110
and outer peripheral terminals fixed to the case
101
by outer peripheral terminal members
111
and
112
.
The inner peripheral terminal members
109
and
110
and the outer peripheral terminal members
111
and
112
are placed at the same position or different positions with respect to both the cables
104
and
105
. In the example shown in the figure, the inner peripheral terminal members
109
and
110
are placed at almost symmetrical positions with respect to the rotation center and the outer peripheral terminal members
111
and
112
are placed at the same position.
The inner peripheral terminal members
109
and
110
are housed separately in inner peripheral terminal spaces
113
and
114
provided swelling inwardly at two parts of the inner periphery of the rotor
102
and the outer peripheral terminal members
111
and
112
are housed together in an outer peripheral terminal space
115
provided swelling outwardly at one part of the outer periphery of the case
101
. Outer wiring of the steering wheel side and outer winding of the body side are connected to the terminal members
109
,
110
,
111
, and
112
.
Problem to be Solved
However, in the rotation connection unit having the inversion-type double-winding structure, the following problems occur:
(1) When the steering wheel is turned at high speed, a discrepancy occurs between the rotation speed of the guide ring
106
and the move speed of cable's inner and outer peripheral portions
104
b
,
104
c
,
105
b
, and
105
c
and a situation in which coming and going of the cable inversion part
104
a
,
105
a
relative to the guide groove
107
,
108
is too late occurs.
In this case, a phenomenon in which the cable's outer peripheral portions
104
c
and
105
c
stick to the guide ring
106
so as to fasten the guide ring
106
from the outer periphery occurs and accordingly it is feared that rotation resistance of the guide ring
106
may grow.
(2) Both the cables
104
and
105
differ in fixing positions of inner and outer peripheral terminals and thus are set to difference lengths. If the lengths vary because of manufacturing tolerances, a situation in which the length difference to be provided between both the cables shifts from the setup value occurs.
If such a situation occurs, the relative positions of the inversion parts
104
a
and
105
a
of both the cables
104
and
105
shift and thus either of them is hard to be well housed in the guide groove
107
,
108
at the assembling time.
In this case, in the rotation connection unit in the related art having no flexibility of the cable length, there is little room for absorbing the cable length discrepancy from the setup value and thus it becomes difficult or impossible to assemble or as a result of forcibly passing the cable inversion parts
104
a
and
105
a
through the guide grooves
107
and
108
, it is feared that smooth motion of the guide ring
106
may be hindered.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a rotation connection unit for making it possible to provide the length of a cable outer peripheral portion with flexibility.
Means for Solving the Problem
According to the invention as in aspect
1
, there is provided a rotation connection unit wherein an inner member and an outer member are fitted for relative rotation in a state in which a cable housing space is formed between the inner member and the outer member, wherein a plurality of conduction cables are housed in the cable housing space in a state in which the winding direction is inverted at an intermediate point and the cables move with relative rotation of both the members, and wherein a guide ring for guiding moving of the cables is placed rotatably and is formed with a plurality of guide grooves through which inversion parts of the cables are passed at different positions, characterized in that the cables are housed in the cable housing space in a state in which a force in a direction touching the inner periphery of the outer member is given.
According to the configuration, the cable is housed in the cable housing space in a state in which the force in the direction touching the inner periphery of the outer member is given, so that the cable outer peripheral portion can be changed with a constant margin. The length of the cable outer peripheral portion is thus provided with flexibility, whereby if the rotation connection unit is rotated at high speed, a phenomenon in which the cable outer peripheral portion sticks to the guide ring so as to fasten the guide ring
6
from the outer periphery does not occur, so that an increase in the rotation resistance of the guide ring can be prevented. Shift from the setup value caused by cable length manufacturing tolerances can be absorbed, assembling the rotation connection unit is facilitated, or smooth motion of the guide ring can be provided.
For example, as in aspect
2
, the cable maybe formed longer than the length of the outer peripheral portion of the cable touching the outer periphery of the guide ring, whereby the force in the direction touching an inner periphery of the outer member is given.
Further, as in aspect
3
, if the rotation connection unit comprises terminal position adjustment means for attaching a terminal member attached to a terminal of the cable to the outer member or the inner member so that the position of the terminal member can be adjusted in a length direction of the cable, the cable outer peripheral portion can be changed with a constant margin by adjusting the position of the terminal member.
For example, as in aspect
4
, the terminal position adjustment means may comprise a plurality of engaged parts formed in the outer member or the inner member at p

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