Brakes – Vehicle
Reexamination Certificate
2000-07-14
2001-06-05
Oberleitner, Robert J. (Department: 3613)
Brakes
Vehicle
C188S10600P
Reexamination Certificate
active
06241051
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a drum brake device activated by a brake cable such as a parking brake, and more particularly, to a brake cable connecting device for connecting the brake cable to a brake lever within the drum brake in a blind manner.
BACKGROUND OF THE INVENTION
As a brake cable connecting device for a drum brake, a forward-pull type parking brake device is known wherein a brake cable is connected to a free end of a brake lever in the drum brake while a base end of the brake lever is pivotally mounted on a shoe web of one of the brake shoes.
The brake cable that activates the brake lever by being pulled from a distance is comprised mainly of an inner cable and an outer casing. At the free end of the brake lever, there is provided with a cable retaining groove bent into U-shape in cross section. One end of the inner cable is connected to a brake application device such as a hand lever in a driver's compartment, and the other end of the inner cable is inserted into the drum brake through an opening in a back plate and is fit in the cable retaining groove of the brake lever.
When an enlarged cable end fixed to the other end of the inner cable engages on an edge surface of the cable retaining groove opposite to a cable pulling direction, the brake cable is completely installed in the cable retaining groove. When the hand lever is operated in the driver's compartment, the inner cable is pulled accordingly, which rotates the brake lever to open a pair of brake shoes to activate the parking brake.
In a brake device of this kind, when the brake cable is pre-installed, several disadvantages are incurred such as a problem of maintaining associated parts, increase in space required for transportation, and/or damages in the brake cable or other components. Thus, it is desirable not to install the brake cable in the assembly process of the brake device, but to do it during the assembly process of the automobile.
However, in general, the brake lever in the drum brake is arranged under the shoe web of the brake shoe, i.e., the back plate side of the shoe web, which makes it difficult to engage the cable end with the brake lever. After the drum brake is covered with the brake drum, it becomes further difficult to specify the location of the brake device to install the brake cable.
Therefore, the connecting device for easily fastening the brake cable to the brake lever is proposed in the U.S. Pat. No. 5,002,159. In this patent, a guide pipe having a curved shape is fixed to an opening of the back plate where also an outer casing of the brake cable is connected so that the cable end passing through the guide pipe is aligned in the cable retaining groove of the brake lever.
However, in the brake cable connecting device disclosed in this patent, in order to align the cable end accurately in the cable retaining groove of the brake lever, the guide pipe must be extended to be close enough to the cable retaining groove. When the space between the end of the guide pipe and the cable retaining groove is decreased, it causes a problem that the brake lever interferes with the guide pipe during its operation. Therefore, it is difficult to compromise both requirements described above.
The assignee of this invention proposed an improved version of the brake cable connecting device which is disclosed in the Japanese Patent Laid Open Publication No. 10-220506. This conventional device is reproduced in
FIGS. 8 and 9
and described below.
FIG. 8
is a plan view showing a leading-trailing type (hereinafter “LT type”) drum brake and
FIG. 9
is a perspective view showing an essential portion of the brake cable connecting portion of FIG.
8
. As shown in
FIG. 8
, brake shoes
1
and
2
arranged symmetrically at right and left in the brake device have a structure identical to each other and comprise crescent-shaped shoe webs
1
a
and
2
a
and shoe rims
1
b
and
2
b
connected respectively in T-shape in cross section. Brake linings
1
c
and
2
c
are respectively adhered to the outer surfaces of the shoe rims
1
b
and
2
b.
The brake shoes
1
and
2
are elastically supported on a back plate
5
by shoe hold means
3
and
4
. The lower adjacent ends of the brake shoes
1
and
2
are abutted against an anchor member and are limited to be lifted from the back plate
5
by a retaining plate
6
. Further, the upper adjacent ends of the brake shoes
1
and
2
are respectively engaged with corresponding pistons of a wheel cylinder
7
.
Between the brake shoes
1
and
2
, an upper shoe return spring
8
and a lower shoe return spring
9
are respectively provided so as to urge the pair of brake shoes
1
and
2
toward each other. Between the brake shoe
1
and a brake lever
10
is provided with an adjuster
13
to be able to adjust the clearance between the brake drum (not shown) and the brake shoes
1
and
2
.
The brake lever
10
is superposed under the shoe web
2
a
of the brake shoe
2
. A base end of the brake lever
10
is rotatably supported on the shoe web
2
a
with a pin
11
as the fulcrum. A lever return spring
12
arranged between the shoe web
2
a
and the brake lever
10
applies a rotational force to the brake lever
10
with a pivotal point of the pin
11
in a clockwise direction (non-operational position).
FIG. 9
shows the structure in the vicinity of the free end of the brake lever
10
as viewed from the back plate
5
side. A cable retaining groove
10
b,
a guide member
10
c,
and a projection
10
e
are integrally formed on the free end portion of the brake lever
10
. The cable retaining groove
10
b
has a U-shape for retaining an inner cable
14
that constitutes a brake cable. The guide member
10
c
is projected toward the cable pulling direction (hereafter “front”, “front side” or “forward”) from the body side of the cable retaining groove
10
b.
The projection
10
e
is formed on a turn-up portion
10
d
of the cable retaining groove
10
b
and projected toward the direction opposite to the cable pulling direction (hereafter “back”, “backside” or “backward”).
The guide member
10
c
of the brake lever
10
, constituting a cable guide means, is formed in a fan-like shape which is widened toward the tip thereof and has a surface of partially conical or pyramidal. When a cable end
14
a
contacts anywhere on the surface of the widened end of the guide member
10
c,
it can be securely guided to the engagement position along the partially conical or pyramidal surface. A ramped surface
10
f
rising backwardly upwardly is formed on the marginal edge of the turn-up portion
10
d
for bending the inner cable
14
into contact with the cable end
14
a
upon advancing the cable end
14
a
thereon.
The connecting procedure of the brake cable is explained in the following. When the inner cable
14
passes through a guide pipe
16
which acts as a cable deflection means from outside (brake outside) of the back plate
5
, the cable end
14
a
is guided toward the guide member
10
c
of the brake lever
10
facing the guide pipe
16
.
When the inner cable
14
is pushed further in the backward direction, the cable end
14
a
is guided from the guide member
10
c
to the ramped surface
10
f
of the turn-up portion
10
d.
When the cable end
14
a
advances further on the ramped surface
10
f
while it bends the inner cable
14
upwardly along to the angle of the ramped surface
14
f,
thereby generating a downward return force in the inner cable
14
, the tip of the cable end
14
a
eventually reaches a plate spring
17
. The cable end
14
a
further advances while deforming the plate spring
17
.
After the cable end
14
a
passes the projection
10
e,
the inner cable
14
immediately moves downward into the cable retaining groove
10
b
by the downward return force thereof as well as a return force of the plate spring
17
. Consequently, the cable end
14
a
is captured by the backside edge of the cable retaining groove
10
b.
Because the cable end
14
a
goes down as noted above, the plate spring
17
returns to its original state by t
Asai Seiji
Ohnishi Junichi
Muramatsu & Associates
Nisshimbo Industries, Inc.
Oberleitner Robert J.
Pezzlo Benjamin A.
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