Turn signal cancel device

Details Turn signal cancel device Turn signal cancel device

2000-11-13

2002-10-29

Scott, J. R. (Department: 2832)

Electricity: circuit makers and breakers

Special application

Turn indicator type switches

C200S061300, C200S061310, C200S061350

Reexamination Certificate

active

06472623

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a turn signal cancel device adapted to automatically return a turn lever, which has been turned to a left turn indicating position or to a right turn indicating position, to a neutral position according to the fact that a steering wheel is rotated in a direction opposite to the direction indicated by the turn lever.
2. Related Art
The configuration of a related turn signal cancel device of such a kind is described hereinafter with reference to
FIGS. 8
to
12
. As shown in
FIGS. 8 and 9
, a cancel cam
1
is a cylindrically shaped member, which has a cancel convex portion la on the outer peripheral portion thereof, and adapted to be integrally rotated with a steering wheel (not shown).
A rectangular box body
2
having opening portions at both lateral end portions is provided in a fixed manner on the right side of this cancel cam
1
. A bracket
3
is provided in the body
2
in such a way as to able to rotate around a shaft portion
3
a
. A base portion of a turn lever
4
is connected to the bracket
3
. A moderation surface portion
5
having alternate formed ridge portions and valley portions is provided on the left-hand inner surface of the body
2
. A moderation piece
6
b
is provided at the end portion of the bracket
3
and is pushed by a moderation spring
6
a
in a direction which the moderation piece
6
b
is press-contacted with the moderation portion
5
. A moderation mechanism
7
includes the moderation surface portion
5
, the moderation spring
6
a
, and the moderation piece
6
b.
The bracket
3
and the turn lever
4
are held selectively at a neutral position, a left turn indicating position (see
FIG. 10
) to which the turn lever
4
is turned therefrom in a direction of an arrow A
1
, and a right turn indicating position (not shown) to which the turn lever
4
is turned therefrom in a direction of an arrow A
2
whose direction is opposite to the direction of the arrow A
1
, as illustrated in
FIGS. 8 and 9
. Incidentally, although not shown, a turn signal switch, whose contacts are switched according to the position of the bracket
3
, is provided in the body
2
.
A back plate
8
is nearly U-shaped as a whole, and includes pressed portions
8
a
and
8
b
at both end portions thereof. The back plate is attached onto a nearly central part of the top surface portion of the bracket
3
in such a manner as to be able to slide in the directions of arrows B
1
and B
2
. A back-plate holding spring
9
for holding the back plate
8
at an intermediate position illustrated in
FIG. 8
by a predetermined force is provided between the back plate
8
and the bracket
3
. A cam portion
10
having a crest part is provided on a left-hand side portion of the top surface of the bracket
3
.
A ratchet
11
is disposed in the top surface portion of the bracket
3
. A shaft portion
11
a
is provided on the middle portion of the ratchet
11
so that the top end of the shaft portion
11
a
is inserted into a guide hole
12
a
, which is an elongated hole formed in a cover
12
(see
FIG. 9
) attached to the top surface portion of the body
2
in such a manner as to be able to move and rotate, and so that the bottom part of the shaft portion
11
a
moves along the cam portion
10
. The ratchet
11
is pushed by a ratchet pushing spring
13
in a direction of an arrow C, that is, to the side of the cancel cam
1
.
In a state in which the bracket
3
(thus, the turn lever
4
) is placed at the neutral position illustrated in
FIG. 8
in the aforementioned configuration, the bottom part of the shaft portion
11
a
of the ratchet
11
is placed at the top of the crest part of the cam portion
10
. The ratchet
11
is held at a position where the leading end portion
11
b
thereof retreats from a rotational locus K (see the position indicated by a chain double-dashed line in
FIG. 8
) of a cancel convex portion
1
a.
When the turn lever
4
is turned from the neutral position thereof in the direction of, for instance, the arrow A
1
, and the bracket
3
is placed at the left turn indicating position illustrated in
FIG. 10
, the ratchet
11
is caused by the pushing force of the ratchet pushing spring
13
to frontwardly move in the direction of the arrow C during the bottom part of the shaft portion
11
a
moves along a slope of the cam portion
10
. Then, the ratchet
11
is put into a state in which the leading end portion
11
b
thereof moves inside the rotational lotus K of the cancel convex portion
1
a.
When the cancel cam
1
is turned in the direction of the arrow D
1
opposed to the indicated direction of the bracket
3
by the steering wheel during this state, the leading end portion
11
b
of the ratchet
11
is pushed in the same direction, so that the ratchet
11
is turned around the shaft portion
11
a
in the direction of an arrow E, and that the rear end thereof pushes the pressed portion
8
a
of the back plate
8
. In the case that this pushing force exceeds the holding force of the moderation mechanism
7
, the bracket
3
(thus, the turn lever
4
) is turned and returned to the neutral position.
In the case that a phenomenon of what is called a grabby brake occurs, for example, the turn lever
4
is held by a driver at the left turn indicating position when the cancel operation is performed, an excessive pushing force
8
a
, which exceeds the holding force of the back-plate holding spring
9
, of the back plate
8
acts on the pressed portion
8
a
of the back plate
8
from the rear end portion of the ratchet
11
. Then, as illustrated in
FIG. 11
, the back plate
8
moves in the direction of the arrow B
1
. This permits the cancel convex portion la to pass therethrough in the direction of an arrow D
1
. Consequently, the ratchet
11
and the back plate
8
are prevented from being damaged when the phenomena of grabby brakes occur.
Incidentally, although the aforementioned operation is performed when the bracket
3
(thus, the turn lever
4
) is turned to the left turn indicating position, a similar operation is performed when the bracket
3
(thus, the turn lever
4
) is turned to the right turn indicating position.
However, the related cancel device has the following problem. That is, let F
1
denote a vector representing the pushing force transmitted from the ratchet
11
to the back plate
8
when the cancel operation is performed as illustrated in FIG.
10
. In this case, a vector F
2
representing the force acting on the back-plate holding spring
9
is established as illustrated in
FIG. 10. A
vector F
3
is a vector representing a vertical reaction force transmitted from the back plate
8
to the ratchet
11
. In this case, the direction of the vector F
1
representing the pushing force transmitted from the back plate
8
to the ratchet
11
is close to the direction of expansion and contraction of the back-plate holding spring
9
(that is, the direction of the arrow B
1
or B
2
, in which the back plate
8
moves). Thus, when the cancel operation is performed, the vector F
2
acting on the back-plate holding spring
9
has a large magnitude and exerts a large influence on the back-plate holding spring
9
.
Thus, even when the cancel operation is performed at the rotational speed of the steering wheel (or of the cancel cam) under ordinary driving conditions, the back plate
8
easily moves. Therefore, as illustrated in
FIG. 12
, an amount of movement of the back plate
8
increases with increase in the rotational speed of the cancel cam
1
(or of the steering wheel) Consequently, a cancel error (that is, even when the ratchet
11
is turned by the cancel convex portion la, the bracket
3
is not returned to the neutral position thereof) easily occurs.
SUMMARY OF THE INVENTION
The present invention is accomplished in view of such circumstances. Accordingly, an object of the present invention is to provide a turn signal cancel device, which has a function of avoiding occurrences of phenomena of grabby brakes in a turn lever, and which can prevent occurrences of

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