Turn signal cancellation mechanism

Details Turn signal cancellation mechanism Turn signal cancellation mechanism

1999-07-20

2001-02-13

Footland, Lenard A. (Department: 3682)

Machine element or mechanism

Control lever and linkage systems

Multiple controlling elements for single controlled element

C200S061300

Reexamination Certificate

active

06186022

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a turn signal canceling mechanism for automatically returning a turn signal lever, which has been turned from a neutral position to a right or a left position so that a proceeding direction of a vehicle can be indicated, to the neutral position when a steering shaft is turned in a direction opposite to the direction of the turn signal lever.
TECHNICAL BACKGROUND OF THE INVENTION
In
FIG. 5
, there is shown a conventional turn signal canceling mechanism. As shown in the drawing, the turn signal canceling mechanism
10
includes: a canceling cam
11
turned integrally with a steering shaft; a turn bracket
14
attached to a case
13
so that the turn bracket
14
can be turned from a neutral position to a right or a left turning position being linked with a turn signal lever
12
; a back plate
16
having a pair of arms
15
which are arranged on the right and left; and a ratchet
17
attached to the case
13
so that the ratchet
17
can be advanced and retracted.
Moderation pieces
18
and moderation springs
19
are respectively incorporated into the right and the left end portions of the turn bracket
14
. These moderation pieces
18
come into pressure contact with moderation ridges
20
arranged in the case
13
. Therefore, the turn bracket
14
can be held at the neutral position, the right turning position or the left turning position by these moderation pieces
18
and the moderation springs
19
. On an upper face of the turn bracket
14
, there are provided a pair of protrusions
21
which are arranged on the right and left, and the back plate
16
is
1
attached to both protrusions
21
in such a manner that the back plate
16
can be linearly reciprocated. The back plate
16
is held at a neutral position by the back spring
22
arranged between both protrusions
21
.
The ratchet
17
has a protrusion
23
formed on the upper face, a protrusion
24
formed on the lower face, and a step portion
25
. The upper protrusion
23
is engaged with a long groove
26
formed on an upper cover of the case, and the lower protrusion
24
slidably comes into contact with a cam face
27
, the profile of which is an angle-shape, arranged inside of the forward end of the turn bracket
14
. There is provided a ratchet spring
28
in the step portion
25
on the lower face. This ratchet spring
28
biases the ratchet
17
toward the canceling cam
11
.
The structure of the conventional turn signal canceling mechanism
10
is described above. As shown in
FIG. 5
, when the turn bracket
14
is located at the neutral position, the lower protrusion
24
slidably comes into contact with a top portion of the ridge of the cam face
27
, and a forward end portion of the ratchet
17
retracts from a rotational locus of the canceling cam
11
.
When the turn lever
12
is operated, the turn bracket
14
is turned to the right turning position or the left turning position and held at the position by the actions of the moderation ridge
20
, moderation piece
18
and moderation spring
19
. When the turn bracket
14
is turned, the lower protrusion
24
, which slidably comes into contact with the top of the ridge of the cam face
27
, slidably comes into contact with a bottom portion. Therefore, the ratchet
17
advances along the long groove
26
, and the forward end portion proceeds into the rotational locus of the canceling cam
11
, and a base end portion of the ratchet
17
comes close to one of the arms
15
.
When the turn bracket
14
is located at the right or the left turning position and also when the canceling cam
11
is turned in the same direction as that of the steering shaft according to the turn of the steering shaft, the canceling cam
11
is engaged with a forward end of the ratchet
17
, and the base end portion of the ratchet
17
is turned in a direction so that it can be separate from the arm
15
which has been located close to the base end portion of the ratchet
17
. On the other hand, when the canceling cam
11
is turned in the opposite direction, the base end portion of the ratchet
17
is engaged with the arm
15
which is located close to it. Therefore, the turn bracket
14
is returned to the neutral position integrally with the back plate
16
.
When the turn signal lever
12
is turned by an operator's hand and held at the position as it is, the turn bracket
14
integrated with the lever
12
is locked at the right turning position or the left turning position. When the canceling cam
11
is turned in the opposite direction under the condition that the turn bracket
14
is locked at the right turning position or the left turning position, the base end portion of the ratchet
17
is engaged with the arm
15
which is located close to it, and a torque of the canceling cam
11
is transmitted to the back plate
16
. Therefore, the back spring
22
is compressed, and the back plate
16
is moved to the right or the left along the protrusion
21
, so that a disengagement of the ratchet
17
is caused.
In this connection, in the above conventional turn signal canceling mechanism
10
, it is necessary to provide three types of springs including the moderation spring
19
, the back spring
22
and the ratchet spring
28
. As a result, the number of parts is large, and the production cost is raised.
The present invention has been accomplished to solve the above problems. It is an object of the present invention to provide a turn signal canceling mechanism capable of lowering the cost by reducing the number of spring types.
SUMMARY OF THE INVENTION
The present invention provides a turn signal canceling mechanism comprising: a canceling cam turned integrally with a steering shaft; a turn bracket attached to a case so that the turn bracket can be turned between a neutral position and a right or a left turning position being linked with the operation of a turn signal lever; a movable member having a pair of arms arranged on the right and left, the movable member being attached to the turn bracket in such a manner that the movable member can proceed and retract, the movable member being biased by a moderation spring so that a moderation mechanism can be composed in which a forward end portion of each arm comes into pressure contact with a moderation ridge formed in the case and the turn bracket is held at one of the neutral position, right turning position and left turning position; and a ratchet attached to the case in such a manner that the ratchet can proceed, retract and turn, the ratchet being biased by a ratchet spring in a direction so that the ratchet can proceed into a rotational locus of the canceling cam, wherein a forward end portion of the ratchet proceeds into the rotational locus of the canceling cam when the turn bracket is turned from the neutral position to the right or the left turning position, a base end portion of the ratchet is turned between both arms when the turn bracket is located at the right turning position or the left turning position and the canceling cam is turned in the same direction, the base end portion of the ratchet is engaged with one of the arms and the turn bracket is returned to the neutral position when the canceling cam is turned to the opposite direction, and the turn bracket, ratchet and movable member are linked with each other so that the base end portion of the ratchet can be engaged with one of the arms and the movable member can be retracted while resisting a biasing force of the moderation spring when the turn bracket is locked at the right turning position or the left turning position and the canceling cam is turned in the opposite direction.
According to the invention, the movable member is retracted while resisting a force generated by the moderation spring. Due to the foregoing, a clearance is caused in the ratchet under the condition that the turn bracket is locked. Therefore, compared with the structure of the conventional turn signal canceling mechanism having two moderation spring, two moderation pieces, a back spring and a back plate, the turn signal can

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