Turn signal switch

Details Turn signal switch Turn signal switch

2002-01-28

2003-02-04

Easthom, Karl D. (Department: 2832)

Electricity: circuit makers and breakers

Special application

Turn indicator type switches

C200S01700A, C200S061270

Reexamination Certificate

active

06515243

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to a turn signal switch (direction indicator) for indicating the right or left turn of an automobile or the like, and more particularly to a self-cancellation technique for automatically returning a turn lever to a neutral position.
A related turn signal switch of this type is shown in
FIGS. 6
to
10
.
FIG. 6
is a cross-sectional view of the turn signal switch, showing a condition in which a steering shaft is disposed in a neutral position, and a turn lever is located in a neutral position,
FIG. 7
is a cross-sectional view of the turn signal switch, showing a condition in which the turn lever is operated to a right position,
FIG. 8
is a cross-sectional view of the turn signal switch, showing a condition in which the steering shaft, after rotated right, is rotated left, and a cam member and a projection are disposed in an interference position,
FIG. 9
is a cross-sectional view of the turn signal switch, showing a condition in which the steering shaft is directly rotated left without being rotated right, and the cam member and a projection are disposed in an interference position, and
FIG. 10
is a cross-sectional view of the turn signal switch, showing its cross-section different from that of
FIGS. 6
to
9
.
As shown in
FIGS. 6
to
10
, the turn signal switch A includes a cancellation cam
1
, and this cancellation cam
1
is so provided as to rotate in accord with the rotation of the steering shaft (not shown). The cancellation cam
1
has a circumferential surface la, and the projections
2
a
and
2
b
are formed respectively on two portions of this circumferential surface
1
a
spaced from each other in the circumferential direction. A cover
4
for receiving parts, described below, is fixedly secured to a box-like member (not shown) substantially covering the outer periphery of the cancellation cam
1
. The turn lever
5
projects from this cover
4
. Abase portion of the turn lever
5
is fixedly secured to an operating member
6
received in the cover
4
.
This operating member
6
is pivotally mounted on the cover
4
through a rotation support pin
7
inserted in a rotation hole
4
a
in the cover
4
, and with this construction the turn lever
5
is operated to be moved from the central neutral position to the right-turn position and the left-turn position. When the turn lever
5
is in the neutral position, the operating member
6
is located in a neutral position, and when the turn lever
5
is in the right-turn position, the operating member
6
is located in a right-operated position, and when the turn lever
5
is in the left-turn position, the operating member
6
is located in a left-operated position. A position-holding pin
9
, on which an urging force of a spring
8
acts, is formed on the operating member
6
, and this position-holding pin
9
is abutted against an inclined stepped surface
10
of the cover
4
. As the operating member
6
is pivotally moved, the position-holding pin
9
slides over the inclined stepped surface
10
, and the operating member
6
is held in the three positions, that is, its neutral position, right-operated position and left-operated position, with a predetermined position-holding force larger than that obtained in the other positions.
The cam member
11
has a pair of support pin portions
12
a
and
12
b
, and one of the pair of support pin portions
12
a
and
12
b
, that is, the support pin portion
12
a
, is inserted in a slot
13
in the cover
4
while the other
12
b
is inserted in a control groove
14
in the operating member
6
. A lower surface of the control groove
14
has an inverted V-shape, and a central portion of this lower surface is disposed at a position spaced from the circumferential surface
1
a
of the cancellation cam
1
, and the distance of this lower surface from the circumferential surface
1
a
of the cancellation cam
1
is decreasing gradually from its central portion toward its opposite sides. When the operating member
6
is located in the neutral position, the other support pin
12
b
is disposed at an apex surface of the inverted V-shape, and a distal end portion
11
a
of the cam member
11
is disposed in a stand-by position (position shown in
FIG. 6
) outside a path of revolution of the projections
2
a
and
2
b
of the cancellation cam
1
. When the operating member
6
is located in the right-operated position or the left-operated position, the other support pin
12
b
is disposed at a bottom point of the inverted V-shape, and the distal end portion
11
a
of the cam member
11
is disposed in the interference position (position shown in
FIGS. 7
to
9
) in the path of revolution of the projections
2
a
and
2
b
of the cancellation cam
1
.
Namely, the cam member
11
can be moved between the interference position and the stand-by position through the control groove
14
in the operating member
6
, and this cam member is supported for rotation about the pair of support pin portions
12
a
and
12
b
. A tension spring
15
(shown in FIGS.
6
and
10
), which is retained at its opposite ends on the cover
4
, and serves as urging means, is engaged at its central portion with the cam member
11
, and the cam member
11
is urged toward the interference position by a spring force of this tension spring
15
.
A ratchet member
16
is mounted on the operating member
6
so as to slide generally in the direction of the circumference of the circumferential surface la of the cancellation cam
1
, and a compression spring
17
and so on are interposed between this ratchet member and the operating member
6
. The ratchet member
16
is pivotally moved together with the operating member
6
by a spring force of this compression spring
17
unless a sliding force, larger than a predetermined value, acts on the ratchet member. The ratchet member
16
has right and left arms
16
a
and
16
b
, and a rear end portion
11
b
of the cam member
11
is disposed in an interference position, and is disposed between the right and left arms
16
a
and
16
b.
Next, the operation of the turn signal switch A of the above construction will be described with reference to
FIGS. 6
to
8
. When the turn lever
5
is disposed in the neutral position as shown in
FIG. 6
, the support pin portion
12
b
of the cam member
11
is disposed at the apex portion of the control groove
14
, so that the cam member
11
is located in the stand-by position. Therefore, even when the cancellation cam
1
rotates in accord with the rotation of the steering shaft (not shown), the cam member
11
does not interfere with the projections
2
a
and
2
b
, and merely the cancellation cam
1
is rotated.
When the turn lever
5
is operated to the right position, with the steering shaft (not shown) held in the neutral condition as shown in
FIG. 7
, the operating member
6
is located in the right-operated position. As a result, the support pin portion
12
b
of the cam member
11
is moved from the apex portion of the control groove
14
in the operating member
6
to the bottom point portion thereof by the spring force of the tension spring
15
, so that the cam member
11
is located in the interference position. The ratchet member
16
rotates together with the operating member
6
, so that one arm
16
a
thereof is located substantially in contact with the rear end portion
11
b
of the cam member
11
.
Then, when the steering shaft (not shown) is rotated right, the cancellation cam
1
is rotated in the right direction (clockwise direction), and the projection
2
a
of the cancellation cam
1
interferes with the distal end portion
11
a
of the cam member
11
, so that the cam member
11
is rotated counter clockwise about the pair of support pin portions
12
a
and
12
b
so as to allow the revolution of the projection
2
a
. This rotation of the cam member
11
will not exert a rotational force on the ratchet member
16
, and therefore the ratchet member
16
will not return the operating member
6
to the neutral position, and therefore the turn lever

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