BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
[0001] The present invention relates to a shaft structure to be installed in
shafts used for various industrial machines such as vehicles, and a male
component and a female component included 5 in the shaft structure.
DESCRIPTION OF THE BACKGROUND ART
[0002] Conventionally, there have been publicly well-known telescopic
shafts each including male and female spline shafts to be incorporated into e.g.
10 vehicle steering shafts (see FIG. 2 in Patent Document 1). Such a telescopic
shaft has splines formed on an outer surface of the male spline shaft and an
inner surface of the female spline shaft. Furthermore, an approximately 0.25
mm thick synthetic resin (nylon or the like) coating is formed on either of the
outer surface of the male spline shaft or the inner surface of the female spline
15 shaft.
[0003] However, the telescopic shafts generate unpleasant noise i.e. the
so-called tooth-hit noise from between the male and female spline shafts,
which are problematic, due to the fact that the dimensional accuracy of such a
20 telescopic shaft is pursued with respect to the splines formed on the outer
surface of the male spline shaft or the inner surface of the female spline shaft.
[0004] Meanwhile, there has been publicly well-known a torque transmission
joint having rubber material such as nitrile rubber, silicone rubber, urethane
25 rubber, and the like disposed in a gap in part between a male spline shaft and a
female spline shaft (see FIG. 2 in Patent Document 2). In such a joint,
rattling vibrations between the male and female spline shafts are absorbed
with the rubber material, thereby resulting in the reduction of rattle noise
(tooth-hit noise) generated therebetween.
30
[0005] (Prior Art Documents)
(Patent Documents)
Patent Document 1: Japanese Patent Application Publication No.
2008-120250
35 Patent Document 2: Japanese Patent Application Publication No.
2009-108892
[0006] (Problems to be Solved)
The torque transmission joints described in Patent Document 2 can
40 reduce the rattle noise; however, the rubber material causes a problem that
sliding resistance in an axial direction is increased between the male spline
3
shaft and the female spline shaft, which results in decrease in slidability with
respect to each other.
SUMMARY OF THE INVENTION
[0007] The objective of the present invention is to provide 5 a shaft structure, a
male component, and a female component capable of reducing unpleasant and
abnormal tooth-hit noise while decreasing sliding resistance in an axial
direction.
10 [0008] (Means for Solving Problems)
[1] A shaft structure according to the present invention is
characterized in that said shaft structure is installed in a shaft capable of
making a power-transmission, and that said shaft structure comprises: a male
component having a plurality of male splines formed on an outer peripheral
15 part thereof; and a female component having a plurality of female splines
formed on an inner peripheral part thereof, the inner peripheral part
configured to allow the outer peripheral part of the male component to be
engaged therein so that the male component and the female component can be
slidably fitted with respect to each other in an axial direction thereby making
20 up said shaft structure, wherein the outer peripheral part of the male
component and the inner peripheral part of the female component have a
fabric impregnated with rubber or resin interposed therebetween.
[0009] According to the construction of [1] above, by virtue of interposing
25 the fabric impregnated with rubber or resin between the outer peripheral part
of the male component and the inner peripheral part of the female component,
tooth-hit noise generated therebetween can be reduced while sliding resistance
in an axial direction therebetween can be decreased. Furthermore, the
improvement of slidability can eliminate the need for lubrication between the
30 outer peripheral part of the male component and the inner peripheral part of
the female component, thereby capable of saving expense in time and effort
with respect to the need for lubricant supply.
[2] A male component according to the present invention is
characterized in that said male component is installed in a shaft capable of
35 making a power-transmission, and is slidably fitted in a female component in
an axial direction, and that said male component comprises: a plurality of
male splines formed on an outer peripheral part, the outer peripheral part of
said male component configured to be engaged in an inner peripheral part of
the female component, wherein the outer peripheral part of said male
40 component has a fabric impregnated with rubber or resin disposed thereon.
[0010] According to the construction of [2] above, by virtue of disposing the
fabric impregnated with rubber or resin on the outer peripheral part of the
4
male component, tooth hit noise generated between the male component and
the female component can be reduced while sliding resistance in an axial
direction therebetween can be decreased. Furthermore, the improvement of
slidability can eliminate the need for lubrication between the outer peripheral
part of the male component and the inner peripheral 5 part of the female
component, thereby capable of saving expense in time and effort with respect
to the need for lubricant supply.
[0011] [3] A female component according to the present invention is
10 characterized in that said female component is installed in a shaft capable of
making a power-transmission, and is slidably fitted to a male component in an
axial direction, and that said female component comprises: a plurality of
female splines formed on an inner peripheral part, the inner peripheral part of
said female component configured to be engaged to an outer peripheral part of
15 the male component, wherein the inner peripheral part of said female
component has a fabric impregnated with rubber or resin disposed thereon.
[0012] According to the construction of [3] above, by virtue of disposing the
fabric impregnated with rubber or resin on the inner peripheral part of the
20 female component, tooth hit noise generated between the male component and
the female component can be reduced while sliding resistance in an axial
direction therebetween can be decreased. Furthermore, the improvement of
slidability can eliminate the need for lubrication between the outer peripheral
part of the male component and the inner peripheral part of the female
25 component, thereby capable of saving expense in time and effort with respect
to the need for lubricant supply.
[0013] [4] As one aspect of [3] above, the female component may further
comprise: a first hole formed on one side of said female component
30 configured to allow the male component to be inserted thereinto in an axial
direction; and a second hole formed on the other side of said female
component configured to allow a rod-shaped component to be pressed therein
in an axial direction and fixed thereto, wherein the first hole may have a first
movement stopper disposed therein, the first movement stopper configured to
35 cause the male component to stop moving in an insertion direction before or at
a predetermined position when the male component is inserted into the first
hole.
[0014] [5] As another aspect of [3] above, the female component may further
40 comprise: a third hole formed on one side of said female component
configured to allow the male component to be inserted thereinto in an axial
direction; and a fourth hole formed on the other side of said female
component configured to allow another male component different from the
male component to be slidably fitted therein in an axial direction, wherein the
5
third hole may have a second movement stopper disposed therein, the second
movement stopper configured to cause the male component to stop moving in
an insertion direction before or at a predetermined position when the male
component is inserted into the third hole, and the fourth hole may have a third
movement stopper disposed therein, the third movement 5 stopper configured to
cause said another male component to stop moving in an insertion direction
before or at a predetermined position when said another male component is
inserted into the fourth hole.
10 [0015] According to the construction of [4] or [5] above, the female
component can be used as a component for connecting (coupling) the male
component and the rod-shaped component. The movement stoppers, in
particular, enable the female component itself to be positioned between the
male component and the rod-shaped component.
15
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] For more thorough understanding of the present invention and
advantages thereof, the following descriptions should be read in conjunction
with the accompanying drawings, in which:
20 FIG. 1 depicts an example of schematic diagram showing an electric
power steering device applied with a shaft structure as an embodiment of the
present invention.
FIG. 2 depicts an example of perspective view showing a shaft
structure as an embodiment.
25 FIG. 3 depicts an exploded perspective view showing main parts of a
shaft structure as an embodiment: (a) an example of a male component, (b) an
example of a female component, and (c) an example of a fabric to be
interposed between the male and female components.
FIG. 4 depicts a perspective view showing modified examples of an
30 embodiment: (a) an example of a male component attached with a fabric such
that the fabric is adhered on an outer peripheral part of the male component
with glue, and (b) an example of a female component attached with a fabric
such that the fabric is adhered on an inner peripheral part of the female
component with glue.
35 FIG. 5 depicts views showing modified example 1 of a female
component in an embodiment: (a) a side view; (b) a view taken along an
arrowed line A-A of (a); and (c) a view taken along an arrowed line B-B of
(a).
FIG. 6 depicts views showing modified example 2 of a female
40 component in an embodiment: (a) a side view; (b) a view taken along an
arrowed line C-C of (a); and (c) a view taken along an arrowed line D-D of
(a).
6
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0017] Hereinafter, a shaft structure (spline) as well as a male component
(male spline shaft) and a female component (female spline shaft), both
components making up the shaft structure, in an embodiment of the present
invention will be described with 5 reference to FIGS. 1-4.
[0018] (Outlined structure of electric power steering device)
Explanations about the elements of an electric power steering device
along with further explanations about the operation of such a device will be
10 provided here. As shown in FIG. 1, the electric power steering device (EPS)
(1) includes: a steering shaft (shaft) (3) connected to a steering wheel (2) as a
steering component; and a rack shaft (6) having a pinion gear (4) disposed on
an end of the steering shaft (3) and a rack gear (5) engaged with the pinion
gear (4), where the rack shaft (6) can serve as a steering shaft extended in a
15 lateral direction of the vehicle.
[0019] The rack shaft (6) has tie rods (7) connected to both ends thereof,
respectively, and the tie rods (7) are connected to their respective wheels (8)
through their respective knuckle arms (not shown). When the steering wheel
20 (2) is manipulated so as to rotate the steering shaft (3), the rotational motion
of the steering shaft (3) is converted by the pinion gear (4) and the rack gear
(5) to the translational motion of the rack shaft (6) in a lateral direction of the
vehicle. As a result, the steering of the wheels (8) can be thus achieved.
25 [0020] The steering shaft (3) is separated into an input shaft (9) connected to
the steering wheel (2) and an output shaft (10) connected to the pinion gear (4).
Such input/output shafts (9, 10) are coupled to each other via a torsion bar
(11) along the same axis. Further, a torque sensor (12) is provided so as to
detect steering torque on the basis of an amount of relative rotational
30 displacement between the input and output shafts (9, 10) with respect to the
torsion bar (11) interposed therebetween, and output torque-detection results
obtained by the torque sensor (12) to a control unit (13). On the basis of:
torque-detection results obtained by the torque sensor (12);
vehicle-speed-detection results; and the like, the control unit (13) controls a
35 driver (14) so as to adjust a voltage applied to an electric motor (15) for
assistance in steering. Still further, the rotation of a rotary shaft (not shown)
in the electric motor (15) is decreased in speed through a speed reducer (17).
The outputted rotational motion of the speed reducer (17) is converted through
a converter (18) to the translational motion of the rack shaft (6) in an axial
40 direction, thereby resulting in assistance in steering. This electric power
steering device (1) is that of the so-called rack assist type.
[0021] (Structure of shaft structure)
7
The shaft structure in an embodiment described above is applied e.g.
to the steering shaft (3) described above (hereinafter, occasionally referred to
as “shaft (3)” for short).
[0022] The shaft structure (20) according to the present 5 invention is installed
on a shaft 3 capable of making a power-transmission. The male and female
components capable of making a power-transmission are slidably fitted with
respect to each other in an axial direction, thereby making up such a shaft
structure (20). The shaft structure (20), as shown in FIG. 2, includes a
10 metallic male component (21), a metallic female component (22), and a fabric
(23) impregnated with rubber or other material.
[0023] The male component (21), as shown in (a) of FIG. 3, has a
substantially cylindrical linchpin (21a) and a convex part (21b) projecting
15 from the end of the linchpin (21a). The outer peripheral part (21c) of the
convex part (21b) has e.g. eight male splines (21d) positioned at
predetermined intervals in a circumferential direction around the convex part
(21b).
20 [0024] The female component (22), as shown in (b) of FIG. 3, is formed into
a substantially cylindrical shape and has an inner peripheral part (22a)
configured such that the male component (21) can be inserted thereinto, and
its outer peripheral part (21c) can be engaged therein. In other words, the
inner peripheral part (22a) of the female component (22) has the structure of
25 eight female splines (22b) (the number of the splines must be the same as that
of the male splines on the convex part (21b) of the male component (21),
therefore eight (8) in this embodiment) positioned at predetermined intervals
in a circumferential direction around the female component (22).
30 [0025] The fabric (23) may be made of, e.g., aramid fiber, nylon, urethane,
cotton, silk, linen, acetate, rayon, fluorine-containing fiber, polyester, and the
like, which are impregnated with rubber or resin. The fabric (23) may be
made of e.g. short fibers or long fibers, and may also be sheet-like fabric.
35 [0026] By virtue of impregnating fibers with rubber or resin, rubber material
or resin material is enabled to fill the gaps among the fibers and bond the
fibers together, thereby allowing the fibers to serve as a component (sheet
body) like a fabric (23). Further, by virtue of impregnating fibers with
rubber or resin, the wear caused by friction between the fibers can be reduced,
40 and still further, the resistance to wear on the surface of the fabric (23) caused
by friction between the fabric (23) and the male component (21) or the female
component (22) can be improved.
8
[0027] The rubber is required to be that with which the fibers can be
impregnated. As such types of rubber, the followings may be used in a neat
form or in a form denatured in various ways: e.g., urethane rubber, nitrile
rubber, silicon rubber, fluororubber, acrylic rubber, ethylene-propylene rubber,
butyl rubber, isoprene rubber, chlorinated 5 polyethylene rubber,
epichlorohydrin rubber, hydrogenated nitrile rubber, chloroprene rubber,
polybutadiene rubber, styrene-butadiene rubber, natural rubber, and the like.
Each of these types of rubber may be used alone, or a plurality of types of
rubber selected therefrom may be used in a blended form. Further, the
10 rubber may contain appropriate amounts of traditional compounding
ingredients for rubber, such as vulcanizing agent, vulcanizing accelerator,
antioxidant, softener, plasticizer, filler, colorant, and the like as well as solid
lubricants such as graphite, silicone oil, fluorine powder, molybdenum
disulfide, or the like for enhancing the lubricity of the fabric (23). Still
15 further, the above types of rubber may be replaced by or combined with
thermoplastic or thermosetting resin such as acrylic resin, polyester resin,
urethane resin, vinyl chloride resin, polypropylene, polycarbonate,
polyethylene terephthalate resin, fluorine resin, polyethylene,
acrylonitrile-styrene resin, acrylonitrile-butadiene-styrene resin, polystyrene
20 resin, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, nylon,
alkyd resin, phenolic resin, epoxy resin, polyphenylene sulfide resin, and the
like.
[0028] When impregnating fibers with rubber or resin as described above, it
25 is preferable that the rubber or resin be dissolved by a solvent or another
means into a liquid state before dipping the predetermined fibers (short or
long fibers) in the liquid. In practice, the sheet-like fabric made of the fibers
may be used. This fabric is impregnated with rubber or resin in the same
way as described above.
30
[0029] The fabric may be, e.g., non-woven fabric made of irregularly tangled
fibers, regularly-formed woven, knitted fabric, or the like. These fabrics are
characterized by facilitating impregnation (easier handling) with rubber and
the like, and further facilitating adhesion to the surface of the shaft structure
35 described below in comparison with those made of fibers (short or long fibers)
only, because these fabrics are in sheet form. The woven fabric may be
made in a plain weave, satin weave, twill weave, or the like.
[0030] The fabric may preferably be stretchy to some extent. By virtue of
40 such stretchiness, when the fabric is formed so as to be in line with the female
splines (22b) or male splines (21d) in shape, or when the fabric is adhered to a
concave-convex surface of the outer peripheral part (21c) of the male
component (21) and the inner peripheral part (22a) of the female component
(22), there can be achieved the advantageous effects that: the surface of the
9
fabric can easily be shaped in accordance with the concave-convex surface
form; and the fabric (23) has the surface subjected to few creases and
uniformly finished, thereby enabling smooth fitting between the male
component (21) and the female component (22), and further enabling decrease
in sliding resistance generated between: the male 5 component (21) or the
female component (22); and the fabric (23). By producing the fabric (23) in
such a manner that a stretchiness direction of the fabric, in particular, can
coincide with at least a circumferential direction of the cylindrically-shaped
fabric (23), it becomes possible that the surface of the fabric (23) is subjected
10 to fewer creases.
[0031] As shown in FIG. 2, the impregnation-processed fabric (23) is
interposed between the outer peripheral part (21c) of the male component (21)
and the inner peripheral part (22a) of the female component (22) (see (b) of
15 FIG. 3). As shown in (c) of FIG. 3, the impregnation-processed fabric (23)
has an inner surface (23a) substantially the same in shape as the outer
peripheral part (21c) of the male component (21) (see (a) of FIG. 3), and has
an outer surface (23b) substantially the same in shape as the inner peripheral
part (22a) of the female component (22) (see (b) of FIG. 3). In this
20 embodiment, as shown in (a) of FIG. 4, the impregnation-processed fabric (23)
is adhered to the outer peripheral part (21c) of the male component (21).
The adhesive used here may be, e.g., acrylic resin adhesive, olefin adhesive,
urethane resin adhesive, ethylene-vinyl acetate resin adhesive, epoxy resin
adhesive, vinyl chloride resin adhesive, chloroprene rubber adhesive,
25 cyanoacrylate adhesive, silicon adhesive, styrene-butadiene rubber adhesive,
nitrile rubber adhesive, hot-melt adhesive, phenolic resin adhesive, melamine
resin adhesive, urea resin adhesive, resorcinol adhesive, and the like. There
are methods to cure an adhesive for bonding: by heating an adhesive so as to
cause the adhesive to melt as fluid, applying the melting adhesive, and
30 thereafter cooling the applied adhesive; just by heating an adhesive; or the
like.
[0032] In this embodiment, the impregnation-processed fabric (23) is
disposed on an entire circumference of the outer peripheral part (21c) of the
35 male component (21). As illustrated in FIG. 2, the male component (21)
adhered with the fabric (23) has a tip projecting from one end of the female
component (22) in an axial direction. The tip of the male component (21) is
processed appropriately in accordance with circumstances that the shaft
structure (20) is used.
40
[0033] The shaft structure (20) can be manufactured by sequentially
performing the steps of e.g.: cutting the male and female components (21, 22)
having their respective shapes as shown in (a), (b) of FIG. 3 from metal
material (not shown); impregnating the fabric (23) with rubber or the like; and
10
interposing the impregnation-processed fabric (23) between the outer
peripheral part (21c) of the male component (21) and the inner peripheral part
(22a) of the female component (22).
[0034] Further, regarding a method of manufacturing 5 the fabric (23), the
following may be appropriately selected. In order to form the fabric (23)
shown in e.g. (c) of FIG. 3, inner and outer molds for forming the inner and
outer surfaces (23a, 23b), respectively, are prepared. It is a matter of course
that the outer surface of the inner mold and the inner surface of the outer mold
10 have a concave-convex form corresponding to the inner and outer surfaces
(23a, 23b), respectively. Fibers (short fibers, long fibers, or sheet-like
fabric) impregnated with rubber or resin are stuffed between the inner and
outer molds, and thereafter the stuffed fibers are pressed and heated through
the molds. Subsequently, the fibers are removed from between the molds.
15 Still subsequently, fabrics (23) having inner and outer surfaces (23a, 23b)
molded can be obtained.
[0035] Still further, regarding an alternative method of manufacturing the
fabric (23), it may also be formed by: initially making a fabric supposed to fill
20 a gap between an inner mold and an outer mold into a cylindrical shape in
accordance with an outer shape of the inner mold; subsequently disposing the
cylindrically-shaped fabric on the inner mold in accordance with the outer
shape of the inner mold; and thereafter pressing and heating the fabric placed
on the inner mold in a similar manner to the above. In this case, the
25 stretchiness of the fabric enables the fabric (23) to be formed further in
accordance with the concave-convex form of the inner and outer molds. As
a result, the formed fabric (23) having the inner and outer surfaces (23a, 23b)
subjected to no creases and uniformly finished can be manufactured. The
fabric (23) with such uniformly finished surfaces interposed between the male
30 and female components (21, 22) of the shaft structure (20) can result in further
decrease in sliding resistance in an axial direction. By forming the fabric
into a cylindrical shape in such a manner that a stretchiness direction of the
fabric to be formed is aligned at least with a circumferential direction of the
formed fabric (23) in a cylindrical shape, the occurrence of creases can be
35 further reduced.
[0036] The male component (21) having the outer peripheral part (21c)
adhered with the impregnation-processed fabric (23) as shown in (a) of FIG. 4
can be manufactured by performing the following steps, on condition that “the
40 inner mold” in the above-described manufacturing method is replaced with
“the male component (21)”: the step of applying adhesive on a metal surface
of the male component (21); the step of subsequently filling fibers (short
fibers, long fibers, or sheet-like fabric) impregnated with rubber or resin
between the male component (21) and the outer mold; the step of still
11
subsequently pressing and heating the fibers through the outer mold; and
thereafter the step of removing the outer mold, thereby obtaining the male
component (21) having the outer peripheral part (21c) adhered with the fabric
(23) as shown in (a) of FIG. 4. In a similar manner to the above, as an
alternative method, the component shown in (a) of FIG. 5 4 may be obtained by:
initially making a fabric into a cylindrical shape in accordance with an outer
shape of the male component (21); subsequently disposing the
cylindrically-shaped fabric on the male component (21) in accordance with
the outer shape thereof; and thereafter pressing the fabric placed on the male
10 component (21). According to such a method, by virtue of the stretchiness
of the fabric, the surface of the fabric (23) adhered to the outer peripheral part
(21c) of the male component (21) is resistant to the generation of creases, and
is uniformly finished, which results in still further decrease in sliding
resistance in an axial direction between the male and female components (21,
15 22) of the shaft structure (20). By forming the fabric (23) into a cylindrical
shape in such a manner that a stretchiness direction of the fabric to be formed
is aligned at least with a circumferential direction of the male component
(21), the occurrence of creases can be further reduced as described above.
20 [0037] (Examples)
Next, the present invention will be specifically explained with
reference to examples. The following descriptions are provided for the
results of material tests prescribed in Japanese Industrial Standards (JIS) for
examining the usefulness of the fabric (23) in an embodiment (see FIG. 2) as a
25 buffer member. It is to be noted that the present invention shall not be
limited to this example. More specifically, the inventors have conducted the
Pico abrasion test (JIS K 6264-2) as well as the friction coefficient
measurement test (JIS K 7125) using a Heidon tester to compare between
nylon 66 impregnated with nitrile rubber and single-component rubber
30 material made of nitrile rubber (hardness 70, JIS K 6253, Type A Durometer).
[0038] Table 1 below shows the results of the Pico abrasion test, and Table 2
below shows the results of the friction coefficient measurement test. In
Tables 1, 2, the item “Rubber-impregnated” denotes material contained in the
35 fabric (23) in this embodiment, more specifically, the nylon 66 impregnated
with nitrile rubber, and the item “Single-component rubber” denotes the
single-component rubber material made of nitrile rubber for comparison with
the material contained in the fabric (23) in this embodiment.
40 Table 1
Abrasion loss
Rubber-impregnated 2.2 mg
Single-component rubber 9.9 mg
12
Table 2
Friction coefficient
Rubber-impregnated 0.54
Single-component rubber 1.48
[0039] As shown in Table 1, the abrasion loss is 2.2 mg in the nylon 66
impregnated with nitrile rubber, and is 9.9 mg in the single-component rubber
material made of nitrile rubber. It is therefore found 5 that the abrasion loss
can be reduced to approximately one-fifth in the nylon 66 impregnated with
nitrile rubber as compared to the single-component rubber material.
[0040] As shown in Table 2, the friction coefficient is 0.54 in the nylon 66
10 impregnated with nitrile rubber, and is 1.48 in the single-component rubber
material made of nitrile rubber. It is found therefore that the friction
coefficient can be reduced to approximately one-third in the nylon 66
impregnated with nitrile rubber as compared to the single-component rubber
material.
15
[0041] These results demonstrate the superiority of the nylon 66 impregnated
with nitrile rubber as a buffer. More specifically, the results show that the
single-component rubber material formed on the outer peripheral part (21c) of
the male component (21) can indeed reduce the tooth-hit noise generated
20 between the male and female components (21, 22), while increases the sliding
resistance (the friction coefficient is increased). Meanwhile, the fabric (23)
containing the nylon 66 impregnated with nitrile rubber formed on the outer
peripheral part (21c) of the male component (21) can reduce the sliding
resistance (the friction coefficient is decreased more than that of the
25 single-component rubber material formed on the outer peripheral part (21c) of
the male component (21)), and can improve the durability (the abrasion loss is
decreased further than that of the single-component rubber material formed on
the outer peripheral part (21c) of the male component (21)).
30 [0042] (Features of shaft structure in embodiment)
According to the above construction, by virtue of interposing the
fabric (23) impregnated with rubber or the like between the outer peripheral
part (21c) of the male component (21) and the inner peripheral part (22a) of
the female component (22), not only unpleasant tooth-hit noise generated
35 therebetween can be reduced, but also sliding resistance in an axial direction
between the male and female components (21, 22) can be decreased, both of
which reduction/decrease are trade-off related to each other. Further, by
virtue of the improvement of slidability between the male and female
components (21, 22) in an axial direction, the need for lubrication between the
40 outer peripheral part (21c) of the male component (21) and the inner
peripheral part (22a) of the female component (22) can be eliminated, and
13
expense in time and effort can be saved with respect to the need for lubricant
supply. Still further, by virtue of impregnating the fabric (23) with rubber or
resin, the resistance to wear on the surface of the fabric (23) caused by friction
between the fabric (23) and the outer peripheral part (21c) of the male
component (21) or between the fabric (23) and the inner 5 peripheral part (22a)
of the female component (22) can be improved.
[0043] Means for interposing the rubber-impregnated fabric (23) between the
outer peripheral part (21c) of the male component (21) and the inner
10 peripheral part (22a) of the female component (22) are not limited to one sort
of means shown in (a) of FIG. 4, by which the fabric (23) impregnated with
rubber is adhered to the outer peripheral part (21c) of the male component
(21). Another sort of means available is shown in (b) of FIG. 4, by which the
fabric (23) impregnated with rubber is adhered to the inner peripheral part
15 (22a) of the female component (22). In other words, as long as
rubber-impregnated fabric (23) and metal are configured such that they can
slide with respect to each other, the above-described advantageous effects can
be achieved by either of the above two sorts of means. The
rubber-impregnated fabric (23) can be adhered to the outer peripheral part
20 (21c) of the male component (21) or the inner peripheral part (22a) of the
female component (22) by: forming a rubber layer on a rear surface (a surface
to be adhered to the outer peripheral part (21c) of the male component (21) or
the inner peripheral part (22a) of the female component (22)) of the
rubber-impregnated fabric (23) such that the rubber layer is integrated with
25 the fabric (23); and subsequently adhering the rubber layer with adhesive to a
metal surface (a surface of the outer peripheral part (21c) of the male
component (21) or the inner peripheral part (22a) of the female component
(22)), for example. According to such means, the adhesion between the
fabric (23) and the metal surface can be strengthen.
30
[0044] Specific constructions according to the present invention are not
limited to the above embodiments described above with reference to the
drawings. The scope of the present invention is not encompassed by the
above explanations of the embodiment but particularly pointed out by the
35 claims, and the equivalents of the claim recitations as well as all the
modifications within the scope of the claims fall within the scope of the
present invention. Two modified examples 1, 2 will be provided below.
[0045] (Modified example 1)
40 The female component (22) in the above embodiment may be
replaced by a female component (32) shown in FIG. 5 ((a) a side view; (b) a
view taken along an arrowed line A-A of (a); and (c) a view taken along an
arrowed line B-B of (a)). Hereinafter, the female component (32) will be
specifically described. Note that, in (a) of FIG. 5, a transparent view is
14
provided only for the parts (32a1, 32a2) by using a dashed-dotted line for
convenience in the illustration.
[0046] The female component (32) includes a first hole (32a), a second hole
(32b), and a movement stopper (32c) (first movement 5 stopper). The first
hole (32a) is configured such that, when a male component like the male
component (21) in the above embodiment is inserted into the first hole (32a),
the male component slidably fits in the inner peripheral part of the first hole
(32a) (e.g. parts 32a1 and 32a2) along the first hole (32a), and the male
10 component is caused by the movement stopper (32c) to stop moving before or
at a predetermined position (at a bottom of the first hole (32a)). A fabric like
the fabric (23) in the above embodiment is interposed between the male
component and the first hole (32a). The second hole (32b) is configured in a
cylindrical shape such that a rod-shaped component (not shown) having a
15 predetermined diameter can be pressed in and fixed to the second hole (32b).
[0047] According to the above construction, the female component (32) can
be used as a component for connecting (coupling) the male component, which
is the same in sort as the male component (21), and the rod-shaped component.
20 The movement stopper (32c) in particular enables the female component (32)
itself to be positioned between the male component and the rod-shaped
component.
[0048] (Modified example 2)
25 The female component (22) in the above embodiment may be
replaced by a female component (42) shown in FIG. 6 ((a) a side view; (b) a
view taken along an arrowed line C-C of (a); and (c) a view taken along an
arrowed line D-D of (a)). Hereinafter, the female component (42) will be
specifically described. Note that, in (a) of FIG. 6, a transparent view is
30 provided only for the parts (42a1, 42a2, 42b1, 42b2) by using a dashed-dotted
line for convenience in illustration.
[0049] The female component (42) includes a third hole (42a), a fourth hole
(42b), a movement stopper (42c) (second movement stopper), and a
35 movement stopper (42d) (third movement stopper). The third hole (42a) is
configured such that, when a male component like the male component (21) in
the above embodiment is inserted into the third hole (42a), the male
component slidably fits in the inner peripheral part of the third hole (42a) (e.g.
parts 42a1 and 42a2) along the third hole (42a), and the male component is
40 caused by the movement stopper (42c) to stop moving before or at a
predetermined position (at a bottom of the third hole (42a)). A fabric like the
fabric (23) in the above embodiment is interposed between the male
component and the third hole (42a). The fourth hole (42b) is configured
such that, when another male component (not shown) like the male component
15
(21) in the above embodiment is inserted into the fourth hole (42b), the male
component slidably fits in the inner peripheral part of the fourth hole (42b)
(e.g. parts 42b1 and 42b2) along the fourth hole (42a), and the male
component is caused by the movement stopper (42d) to stop moving before or
at a predetermined position (at a bottom of the fourth 5 hole (42b)). A fabric
like the fabric (23) in the above embodiment is interposed between the male
component and the fourth hole (42b).
[0050] According to the above construction, the female component (42) can
10 be used as a component for connecting (coupling) the male component, which
is the same in sort as the male component (21), and another male component.
The movement stoppers (42c, 42d) in particular enable the female component
(42) itself to be positioned between the male component, which is the same in
sort as the male component (21), and the above-described another male
15 component.
[0051] Regarding further modified examples, although the shaft structures in
the above embodiments and modified examples 1, 2 are applied to the steering
shafts for vehicles, the present invention can be applied not only to such shafts
20 in a limitative manner but also to shafts used for various industrial machines.
[0052] In the above embodiments and modified examples 1, 2, there is
described an example of impregnating fibers with rubber or the like; however,
the present invention shall not be limited to such an example, and the fibers
25 are required to be those which can be impregnated with rubber or the like and
which have low sliding resistance against the metal surface, and sheet-like
fabric made of fibers may be used. For example, canvas, velvet, denim,
woven fabric, knitted fabric impregnated with rubber or the like may be used.
Horizontally and/or vertically stretchy fabric may also be used.
30
[0053] In the modified examples 1, 2, each movement stopper at the bottom
of each hole; however, the movement stoppers may be arranged anywhere in
the holes as long as they can stop the movement of the male component before
or at a predetermined position (arbitrarily defined positions) in the holes so as
35 to determine the position of the female component.
[0054] (Reference Numerals)
1 Electric power steering device 2 Steering
wheel
40 3 Steering shaft (shaft) 4 Pinion
gear
5 Rack gear 6 Rack shaft
7 Tie rod 8 Wheel
9 Input shaft 10 Output
16
shaft
11 Torsion bar 12 Torque
sensor
13 Control unit 14 Driver
15 5 Electric motor 17 Speed
reducer
18 Converter 20 Shaft
structure
21 Male component 21a Linchpin
10 21b Convex part 21c Outer
peripheral part
21d Male splines 22, 32, 42 Female
component
22a Inner peripheral part 22b Female
15 splines
32a First hole 32b Second
hole
42a Third hole 42b Fourth
hole
20
32c Movement Stopper (first movement stopper)
42c Movement stopper (second movement stopper)
42d Movement stopper (third movement stopper)
25 23 Woven fabric (fibers) 23a Inner
surface
23b Outer surface
17
We Claim:
1. A shaft structure installed in a shaft capable of making a
power-transmission, the shaft structure comprising:
a male component having a plurality of male 5 splines formed on an
outer peripheral part thereof; and
a female component having a plurality of female splines formed on an
inner peripheral part thereof, the inner peripheral part configured to allow the
outer peripheral part of the male component to be engaged therein so that the
10 male component and the female component can be slidably fitted with respect
to each other in an axial direction thereby making up said shaft structure,
wherein
the outer peripheral part of the male component and the inner
peripheral part of the female component have a fabric impregnated with
15 rubber or resin interposed therebetween.
2. A male component installed in a shaft capable of making a
power-transmission, and slidably fitted in a female component in an axial
direction, the male component comprising:
20 a plurality of male splines formed on an outer peripheral part, the
outer peripheral part of said male component configured to be engaged in an
inner peripheral part of the female component, wherein
the outer peripheral part of said male component has a fabric
impregnated with rubber or resin disposed thereon.
25
3. A female component installed in a shaft capable of making a
power-transmission, and slidably fitted to a male component in an axial
direction, the female component comprising:
a plurality of female splines formed on an inner peripheral part, the
30 inner peripheral part of said female component configured to be engaged to an
outer peripheral part of the male component, wherein
the inner peripheral part of said female component has a fabric
impregnated with rubber or resin disposed thereon.
35 4. The female component according to claim 3 further comprising:
a first hole formed on one side of said female component configured
to allow the male component to be inserted thereinto in an axial direction; and
a second hole formed on the other side of said female component
configured to allow a rod-shaped component to be pressed therein in an axial
40 direction and fixed thereto, wherein
the first hole has a first movement stopper disposed therein, the first
movement stopper configured to cause the male component to stop moving in
an insertion direction before or at a predetermined position when the male
component is inserted into the first hole.
18
5. The female component according to claim 3 further comprising:
a third hole formed on one side of said female component configured
to allow the male component to be inserted thereinto in an axial direction; and
a fourth hole formed on the other side of 5 said female component
configured to allow another male component different from the male
component to be slidably fitted therein in an axial direction, wherein
the third hole has a second movement stopper disposed therein, the
second movement stopper configured to cause the male component to stop
10 moving in an insertion direction before or at a predetermined position when
the male component is inserted into the third hole, and
the fourth hole has a third movement stopper disposed therein, the
third movement stopper configured to cause said another male component to
stop moving in an insertion direction before or at a predetermined position
15 when said another male component is inserted into the fourth hole.