Blade tensioner

Details Blade tensioner Blade tensioner

2001-06-11

2004-01-13

Fenstermacher, David (Department: 3682)

Endless belt power transmission systems or components

Means for adjusting belt tension or for shifting belt,...

Tension adjuster has surface in sliding contact with belt

C474S101000

Reexamination Certificate

active

06676550

ABSTRACT:

FIELD OF THE INVENTION
The present invention pertains to a blade tensioner equipped with a blade shoe having a chain sliding face and several plate-like blade springs for applying a spring force to the blade shoe.
BACKGROUND OF THE INVENTION
Conventionally, a blade tensioner has been utilized as a tensioner for applying tension to a chain. An example of a prior art blade tensioner is shown in FIG.
9
.
As shown in
FIG. 9
, a prior art blade tensioner
100
may be configured primarily with a resin blade shoe
101
having a curved chain sliding face
101
a
and several metal blade springs
102
stacked on the reverse side of the chain sliding face
101
a
of the blade shoe
101
in order to apply a spring force to the blade shoe
101
. Respective ends of the plate-spring-like blade springs
102
may be disposed in concave parts
111
and
113
created at a tip part
110
and a base part
112
of the blade shoe
101
.
In addition, a bracket
120
for installing the blade tensioner
100
into an engine can be provided. Holes
121
and
122
for inserting attachment bolts may be created on the bracket
120
. A sliding face
125
which allows the tip part
110
of the blade shoe
101
to slide while remaining in contact is created at the tip of the bracket
120
, and a pin
130
which supports the base part
112
of the blade shoe
101
while allowing it to pivot freely can be fixed near the center of the bracket
120
by one end.
During the operation of the chain, the chain runs while sliding on the chain sliding face
101
a
of the blade shoe
101
. At this time, a pressing load created as the blade shoe
101
and the blade springs
102
are deformed may act upon the chain, so that constant tension of the chain is maintained. In addition, chord vibrations caused by thrashing of the chain and/or fluctuation of tension are propagated to the respective blade springs
102
in the blade shoe
101
via the blade shoe
101
. At this time, the adjoining blade springs
102
slide against each other as the respective blade springs
102
are repeatedly subjected to elastic deformation and return deformation, and the chord vibrations of the chain are damped.
The blade springs as products are subject to quite significant variation in terms of curvature and length. Thus, when several of the blade springs are stacked and installed into the blade shoe, as shown in
FIG. 10
, contact positions C and C′, contact conditions, and gaps between the respective blade springs
102
may vary.
As a result, the overall damping factor of the blade springs varies, creating a problem that the damping performance of a blade tensioner may vary.
SUMMARY OF THE INVENTION
In accordance with an aspect of the invention, a blade tensioner is provided for applying tension to a chain equipped with a blade shoe having a chain sliding face, several plate-spring-like blade springs stacked on the reverse side of the aforementioned chain sliding face of the aforementioned blade shoe in order to apply a spring force to the aforementioned blade shoe, and spacer members provided between the aforementioned adjoining blade springs and brought in contact with corresponding blade springs at at least two points separated from each other by a fixed distance.
During the operation of the chain, the chain runs while sliding on the chain sliding face of the blade shoe. At this time, a pressing load created as the blade shoe and the blade springs are deformed may act upon the chain, so that constant tension is imparted upon the chain.
What is more, in such case, spacer members may be provided between the respective adjoining blade springs, and the spacer members can be brought in contact with the corresponding blade springs at at least two points separated from each other by a fixed distance.
That is, the respective blade springs can be in contact with the spacer members at junctions of a fixed span instead of at irregular contact points. Accordingly, fluctuation of the damping factor of the overall blade spring or system can be reduced or eliminated, so that the damping performance of the blade tensioner can be stabilized.
In an aspect of the blade tensioner of the invention, almost uniform gaps can be created between the aforementioned adjoining blade springs. In such case, when the pressing load is applied by the chain, uneven contact between the deformed blade springs can be avoided. Accordingly, fluctuation of the damping factor of the overall blade spring due to changes in the contact condition can be prevented.
In a further aspect of the blade tensioner of the invention, the aforementioned spacer member may be configured with several spacer parts laid out at certain intervals in the width direction of the spring and a pair of connector parts extending in the length direction of the spring while connecting the aforementioned respective spacer parts.
In such case, because each spacer part functions to serve as a spacer between blade springs, an almost uniform gap can be created between the blade springs along the length direction of the springs due to these spacer parts. Accordingly, the curvature of the respective blade springs can be made almost uniform. As a result, the damping factor of the overall blade spring can be constant, so that the damping performance of the blade tensioner can be stabilized.
What is more, in such case, because almost uniform gaps can be created between the respective adjoining blade springs, the deformed blade springs can uniformly contact the spacer members to be brought into contact with them as the pressing load is applied by the chain. Accordingly, the damping performance of the overall blade spring can be stabilized. In addition, in such case, because the number of contact faces with the spacer members increases, the damping force of the blade tensioner can be improved.
In yet another aspect of the invention, the aforementioned spacer part may have a cross section in the shape of a circle, an oval, or a rectangle.
According to another aspect of the invention, retainer parts for preventing the aforementioned spacer members from falling off the aforementioned blade springs may be created at the ends of the aforementioned spacer parts.
According to yet another aspect of the invention, the aforementioned connector parts may have a retaining function to prevent the aforementioned spacer members from falling off the aforementioned blade springs.
In another aspect of the invention, the aforementioned spacer members may be created by means of molding or press-punching a net band.
In yet another aspect of the invention, contact faces between the aforementioned spacer members and the aforementioned blade springs may be provided with a friction material. In such case, the damping force can be increased by the spacer members; and the damping performance of the blade tensioner can be improved accordingly.


REFERENCES:
patent: 1036247 (1912-08-01), Huston
patent: 1127511 (1915-02-01), Potter
patent: 1265623 (1918-05-01), Currey
patent: 1678035 (1928-07-01), Davis
patent: 1743049 (1930-01-01), Smith
patent: 1745269 (1930-01-01), Pilz
patent: 4832664 (1989-05-01), Groger et al.
patent: 5462493 (1995-10-01), Simpson
patent: 5984815 (1999-11-01), Baddaria

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