U.S. patent application number 10/226900 was filed with the patent office on 2003-03-13 for synthetic resin guide for transmission device.
Invention is credited to Konno, Masahiko.
Application Number | 20030050140 10/226900 |
Document ID | / |
Family ID | 19100502 |
Filed Date | 2003-03-13 |
United States Patent
Application |
20030050140 |
Kind Code |
A1 |
Konno, Masahiko |
March 13, 2003 |
Synthetic resin guide for transmission device
Abstract
A synthetic resin guide for a transmission device comprises an
elongated rail for longitudinal sliding engagement with a power
transmission medium, and a rail supporting member molded as a unit
with the rail. The supporting member comprises a plurality of
reinforcing ribs which support the rail. The ribs are distributed
along the length of the transmission device from a location
adjacent one end of the rail to a location adjacent the opposite
end of the rail. The guide is formed by injection molding and the
reinforcing ribs extend in directions following the flow of
synthetic resin during injection molding. Preferably the synthetic
resin is a glass fiber reinforced resin. By forming the reinforcing
ribs in this manner, high strength and toughness are imparted to
the guide, and warpage and torsion, which would otherwise be
encountered in a high temperature transmission environment, are
reduced.
Inventors: |
Konno, Masahiko; (Osaka,
JP) |
Correspondence
Address: |
HOWSON AND HOWSON
ONE SPRING HOUSE CORPORATION CENTER
BOX 457
321 NORRISTOWN ROAD
SPRING HOUSE
PA
19477
US
|
Family ID: |
19100502 |
Appl. No.: |
10/226900 |
Filed: |
August 23, 2002 |
Current U.S.
Class: |
474/111 |
Current CPC
Class: |
F16H 2007/0872 20130101;
F16H 7/18 20130101 |
Class at
Publication: |
474/111 |
International
Class: |
F16H 007/08 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 11, 2001 |
JP |
275680/2001 |
Claims
I claim:
1. A synthetic resin guide for a transmission device comprising an
elongated rail for longitudinal sliding engagement with a power
transmission medium, and a rail supporting member molded as a unit
with said rail, the supporting member comprising a plurality of
reinforcing ribs which support said rail, the ribs being
distributed along the length of the transmission device from a
location adjacent one end of the rail to a location adjacent the
opposite end of the rail, wherein the guide is formed by injection
molding and said reinforcing ribs extend in directions such that
the flow of synthetic resin during injection molding substantially
follows the longitudinal directions of the reinforcing ribs.
2. A synthetic resin guide according to claim 1, in which said
synthetic resin is a glass fiber reinforced resin.
Description
FIELD OF THE INVENTION
[0001] This invention relates to guides for sliding engagement with
chains, belts and other power transmission media such as those used
in a motor vehicle engine or the like for transmitting power from a
driving sprocket or pulley to a driven sprocket or pulley. These
guides may be fixed guides, or movable guides associated with
tensioners. More specifically, the invention relates to
improvements in guides formed of synthetic resins.
BACKGROUND OF THE INVENTION
[0002] In general, in a transmission device for a motor vehicle
engine or the like, in which mechanical power is transmitted by a
medium such as a chain, belt or the like, a movable or fixed guide
is attached to a body frame, such as an engine block wall, by a
mounting bolt, a pin or the like. The chain, belt, or other power
transmission medium, travels in sliding contact with the guide
[0003] In the case of a movable guide, which may be in the form of
a tension lever or the like, the guide provides the power
transmission medium with appropriate tension to prevent
transmission failure resulting from excessive stretching, or
excessive loosening, of the power transmission medium. A fixed
guide, such as a guide rail or the like, limits the power
transmission medium to a predetermined traveling path to prevent
vibration noise, side vibration, and disengagement.
[0004] FIG. 13 illustrates an example of a conventional synthetic
resin guide 100 for a tensioner lever. The guide 100 comprises a
slide rail 101, which is in sliding contact with a traveling chain
C, and a rail-supporting member 102 provided on the back side of
the slide rail 101. The rail supporting member 102 includes a boss
102a having a mounting hole 103 for pivoting attachment to an
engine block wall. The rail supporting member also includes a
tensioner abutting portion 102b, which cooperates with a tensioner
(not shown) for providing appropriate tension to prevent
transmission failure resulting from excessive stretching, or
excessive loosening, of the chain. The synthetic resin guide 100
includes a plurality of thick reinforcing ribs 102c, each formed at
suitable intervals along the rail supporting member 102, to enhance
the mechanical properties and toughness of the guide 100.
[0005] The conventional synthetic resin guide 100 has several
problems preventing it from exhibiting good mechanical properties
and toughness. When the guide is injection-molded from an injection
gate provided on one end portion of the guide, the reinforcing ribs
102c extend substantially perpendicular to the direction of
injection of the synthetic resin P. As a result of the orientation
of the reinforcing ribs, the flow of the injected synthetic resin
P, which, as shown in FIG. 14, comprises a skin layer-forming resin
P1 and a core layer-forming resin P2, exhibits a stagnant fluid
state within and around the interior of the reinforcing ribs 102c.
The residence, eddy flow, and turbulent flow of the resin P prevent
the resin from achieving a strain-free molecular orientation in the
interior of the reinforcing ribs 102c. Consequently, the peripheral
portions of the ribs are solidified in an strained state. The
orientation strain not only causes cracks due to loading during
power transmission, but also causes thermal shrinkage resulting
from a non-crystalline region in the synthetic resin P.
Accordingly, strains such as warpage, torsion and the like occur in
a high temperature environment such as in an automobile engine, and
the guiding function is not entirely satisfactory.
[0006] Referring to FIGS. 15 and 16, when a synthetic resin P,
composed of a glass fiber reinforced resin (consisting of a skin
layer forming resin P1 and a core layer forming resin P2) is used,
ideal mechanical properties and toughness are exhibited when the
reinforcing glass fibers F contained in the core layer forming
resin are oriented in a direction substantially parallel to the
slide rail 101. However, as described above, since the reinforcing
rib portions 102c extend substantially perpendicular to the
direction of injection of the synthetic resin P, the resin is in a
stagnant fluid state in the interiors of the respective reinforcing
ribs 102c, and in the peripheral portions thereof. Residence, eddy
flow, turbulent flow and the like are generated in the fluid resin,
and, as a result, as shown in FIG. 16, the orientation of the glass
fibers is disturbed. Thus, in spite of the mixing of glass fibers F
in the synthetic resin P to increase the strength of the guide,
ideal strength cannot be achieved.
[0007] Furthermore, since the reinforcing rib portions 102c impair
the flow of the glass fiber-reinforced synthetic resin P,
moldability during injection molding is unsatisfactory. Thus, glass
fibers F cannot be dispersed in such a way that they are oriented
in a specified direction, and cannot be mixed uniformly in the
resin. To solve this problem, changing the injection conditions has
been tried. However, a higher injection pressure and a longer
injection time are required, thereby increasing the cost of
injection molding.
[0008] Accordingly, objects of the invention are to solve the
above-mentioned problems encountered in the prior art, and to
provide a synthetic resin guide for a transmission device including
reinforcing portions, which exhibits greater strength and
toughness, and in which strains such as warpage, torsion and the
like in a high temperature environment are significantly
reduced.
[0009] The synthetic resin guide in accordance with the invention
comprises an elongated rail for longitudinal sliding engagement
with a power transmission medium, and a rail supporting member
molded as a unit with the rail. The supporting member comprises a
plurality of reinforcing ribs which support the rail. These ribs
are distributed along the length of the transmission device from a
location adjacent one end of the rail to a location adjacent the
opposite end of the rail. The guide is formed by injection molding,
and, in order to achieve the above-mentioned objects, the
reinforcing ribs extend in directions such that the flow of
synthetic resin during injection molding substantially follows the
longitudinal directions of the reinforcing ribs. Preferably, the
synthetic resin is a glass fiber reinforced resin. The synthetic
resin guide in accordance with the invention, may be either a fixed
guide or a movable guide.
[0010] In order for the reinforcing ribs to extend in a direction
following the flow of resin during injection molding, any
arrangement such as an S-shaped arrangement, a curved arrangement,
a truss-shaped arrangement, a vein-shaped arrangement, a
honeycomb-shaped arrangement, or the like, may be used.
[0011] The injection molding process used to produce the synthetic
resin guide according to the invention can be an injection molding
process in which resin processing is integrally carried out from
one end portion in a longitudinal direction of the guide toward the
other end portion. For example, any process such as a typical
injection molding process using a single synthetic resin, a
two-color injection molding process using two kinds of synthetic
resins, a sandwich injection molding process in which a core layer
resin is injected inside a skin layer, or the like, may be
used.
[0012] According to the invention the reinforcing rib portions
which supports the slide rail extend in directions following the
flow of synthetic resin during injection molding of the guide. Thus
the reinforcing rib portions behave as auxiliary flow paths, which
lead the synthetic resin injected during the injection molding of
the guide from one end portion in a longitudinal direction of the
guide toward the other end portion, so that injected synthetic
resin flows throughout the guide without significant flow
resistance, so that the injected synthetic resin flows smoothly to
the end of the synthetic resin guide.
[0013] Since the synthetic resin is fully molecularly-oriented when
solidified, the crystal region of the synthetic resin is increased
and thermal shrinkage of the guide is reduced. Furthermore, the
pressure required for injection molding of the guide can be reduced
to a lower level than in the conventional case, and the injection
time can also be reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a front elevational view illustrating a
transmission guide in accordance with the invention in use in a
motor vehicle engine;
[0015] FIG. 2 is a schematic elevational illustrating the flow of
resin during injection molding of a guide in accordance with the
invention;
[0016] FIG. 3 is a cross-sectional view of a reinforcing rib taken
on plane A-A in FIG. 2;
[0017] FIG. 4 is a cross-sectional view corresponding to FIG. 3,
but illustrating a case in which a glass fiber reinforcing resin is
used;
[0018] FIG. 5 is a schematic elevational view showing the
relationship between an S-shaped reinforcing rib and the flow of
resin;
[0019] FIG. 6 is a schematic elevational view showing the
relationship between a truss-shaped reinforcing rib and the flow of
resin;
[0020] FIG. 7 is a schematic elevational view showing the
relationship between radial, linear, reinforcing ribs and the flow
of resin;
[0021] FIG. 8 is a schematic elevational view showing the
relationship between radial, curved, reinforcing ribs and the flow
of resin;
[0022] FIG. 9 is a schematic elevational view showing the
relationship between linear, vein-shaped, reinforcing ribs and the
flow of resin;
[0023] FIG. 10 is a schematic elevational view showing a
relationship between curved, vein-shaped, curve reinforcing ribs
and the flow of resin;
[0024] FIG. 11 is a schematic elevational view showing the
relationship between honeycomb-shaped reinforcing ribs and the flow
of resin;
[0025] FIG. 12 is a schematic elevational view showing the
relationship between reinforcing ribs formed in a number-sign
pattern and the flow of resin.
[0026] FIG. 13 is a view illustrating an example of a conventional
synthetic resin guide for a transmission device;
[0027] FIG. 14 is a cross-sectional view taken on plane B-B in FIG.
13;
[0028] FIG. 15 is a view showing the ideal orientation of glass
fibers in a guide; and
[0029] FIG. 16 a cross-sectional view taken on plane B-B in FIG. 13
illustrating a case in which a glass fiber reinforcing resin was
used.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] Preferred embodiments of a synthetic resin transmission
device guide according to the invention for a (hereinafter referred
to as a transmission guide) will be described below with reference
to the drawings.
[0031] As shown in FIG. 1, a transmission, for valve timing in a
motor vehicle engine, transmits power by means of a chain C, which
travels around a driving sprocket S1 and driven sprockets S2 in a
circulating path. A movable transmission guide 10 guides, and
applies tension to, the chain C, as the chain slides on the guide.
A fixed guide L, along which the chain slides, is also provided.
However, unlike the transmission guide 10, the fixed guide does not
have a reinforcing rib portion.
[0032] As shown in FIG. 2, the transmission guide comprises a slide
rail 11, having on one side a substantially arc-shaped sliding
contact surface on which a chain C slides, and, on its opposite
side, a rail supporting member 12, which extends in perpendicular
relationship to the sliding contact surface, along the length of
the guide. The rail supporting member 12 includes a boss 12a having
a mounting hole 13, for pivotally mounting the guide on a wall of
an engine block so that it can serve as a movable guide, and
portion 12b for abutting a tensioner T (FIG. 1), in order to apply
appropriate tension to the chain C to prevent transmission failure
resulting from excessive stretching or loosening of the chain. The
guide also has reinforcing rib portions 12c which serve both a
reinforcing and weight-reducing function.
[0033] The slide rail 11 and rail supporting member 12 are
integrally molded as a unit by injection molding. A synthetic resin
P is injected through a gate G, provided at one end in the
longitudinal direction of the guide. The reinforcing rib portions
12c extend in an S-shaped configuration, to correspond to the
direction of injection of the synthetic resin P. Consequently, the
synthetic resin P, injected through the gate G, flows to the
reinforcing rib portions 12c along an auxiliary flow path as shown
by arrows D in FIG. 2, so that the resin is injected into the
entire guide with a minimum of flow resistance. The resin P does
not remain stationary at the reinforcing rib portions 12c during
injection molding, and no eddy flow or turbulent flow occurs.
Consequently, the synthetic resin P can be injected smoothly to the
end of the guide opposite the gate G. As a result, the synthetic
resin P is molecularly oriented when it is solidified.
[0034] The transmission guide 10 thus obtained has an increased
crystal region of injection-molded synthetic resin P, and
accordingly, the strength and toughness of the guide are
dramatically improved. Further, because the crystal region is
increased, thermal shrinkage of the guide is reduced, strains such
as warpage, torsion and the like are less likely to occur even in a
high temperature transmission environment, and a stable
transmission guiding function can be achieved.
[0035] As illustrated in FIG. 3, a sandwich injection molding
process may be used to form the transmission guide. In sandwich
injection molding, a resin P2, which forms a core layer, is
injected into the interior of a sheath composed of a resin P1,
which forms a skin layer. As shown, the core layer is injected into
the interior of the reinforcing rib portions 12c. Since the
injection ratio of the core layer forming resin P2 can be
increased, the strength and toughness of the guide can be
improved.
[0036] When the core layer resin P2 consists of a glass fiber
reinforced resin, the reinforcing glass fibers F are uniformly
dispersed in the resin and oriented in the injection direction (the
direction of the normal to the a cross section in FIG. 4). With the
use of glass fibers, the strength and toughness of the guide can be
further enhanced.
[0037] The transmission guide 10 can be produced by a conventional
injection molding apparatus, except that the mold is shaped so that
the reinforcing ribs follow the direction of injection of the
synthetic resin P during injection molding.
[0038] The synthetic resins P, used for the transmission guide 10
are not particularly limited, and any one of the synthetic resins,
which have been used in the injection molding, such as nylon 6,
nylon 66, nylon 46, all aromatic nylons and the like, may be
used.
[0039] Although the reinforcing ribs 12c in the above example are
in the form of an S-shaped curve substantially following the
injection direction of the synthetic resin P, the reinforcing ribs
can be arranged in various other forms, as shown in FIGS. 5 to
12.
[0040] By adopting an arrangement in which the reinforcing ribs
form a plurality of connected triangles, as shown in FIG. 6, a
truss-shaped arrangement is achieved. Inner stress, generated when
the guide 10 is under load, can be balanced, and its bending
strength and toughness can be enhanced.
[0041] As shown in FIGS. 7 and 8, a plurality of reinforcing ribs
12c are disposed in a radiating pattern which begins at the slide
rail, which is at the outer end of the radiating pattern. The
radiating ribs extend along the direction of flow of the synthetic
resin P. A resulting enhanced fluidity of the resin during
injection molding contributes to a reduction in injection pressure
and a reduction in injection time.
[0042] As shown in FIGS. 9 and 10, a plurality of reinforcing ribs
12c extend in a vein-shaped arrangement. These ribs extend
outwardly from a central rib which extends longitudinally in a
direction substantially parallel to the slide rail. The synthetic
resin P can be injected uniformly into the entire guide, since the
flow of resin follows the directions of the ribs during injection
molding. In these embodiments, the bending strength and toughness
of the guide are further enhanced.
[0043] As shown in FIGS. 11 and 12, reinforcing ribs 12c are
disposed in a honeycomb-shaped arrangement or a number sign- or
pound sign-shaped arrangement. Here again, the flow of resin during
injection molding follows the directions of the ribs, and the
strength of the guide is enhanced.
[0044] In accordance with the invention, the reinforcing ribs of a
slide rail supporting member extend in a direction such that the
flow of synthetic resin P during injection molding follows the
longitudinal directions of the ribs. Thus, the resin is molecularly
oriented when it is solidified in such a way that the strength and
toughness of the guide are dramatically improved. Furthermore, the
crystal region of the resin injected into the guide is increased so
that thermal shrinkage of the guide is decreased, and warpage,
torsion and the like are reduced, even in a high temperature
environment, and a stable guiding function is achieved. The
injection pressure and injection time are also reduced, and a the
production cost of the guide can be significantly reduced.
[0045] When the synthetic resin is a glass fiber-reinforcing resin,
the orientation of the glass fibers F in the longitudinal direction
of reinforcing ribs can be enhanced significantly, and a more
uniform dispersion of the reinforcing glass fibers can be achieved.
As a result, the strength of the guide can be significantly
increased.
* * * * *