SPECIFICATION
YOKE FOR CROSS SHAFT UNIVERSAL JOINT AND
METHOD FOR MANUFACTURING THE SAME
5 TECHNICAL FIELD
[0001]
The invention relates to an improved yoke constituting, for example, a cross
shaft universal joint ( cm·dan joint) for connecting together rotation shafts constituting a
vehicle steering apparatus in a torque transmittable manner.
10
BACKGROUND ART
[0002]
A vehicle steering apparatus is structured as shown in Fig. 7. The movement
of a steering wheel I to be operated by a driver is transmitted to an input shaft 6 of a
15 steering gear unit 5 through a steering shaft 2, a universal joint 3, an intermediate shaft
4 and another universal joint 3. And, a pair of right and left tie rods 7, 7 are pushed
and pulled by a rack and opinion mechanism built in the steering gear unit 5 to thereby
apply proper steering angles to a pair of right and left steering wheels according to the
operation amount of the steering wheel 1. Here, as the intermediate shaft 4, generally,
2 0 there is used a shaft structured such that, as shown in Fig. 8, the one-side ends of an
outer shaft 8 and an itmer shaft 9 are serration engaged with each other to thereby
enable torque transmission and contraction in a collision accident. The universal
joints 3, 3 are connected to the other-side ends of the shafts 8, 9.
[0003]
25 As the universal joints 3, 3 to be incorporated into the steering apparatus,
1
there are used, for example, such cross shaft universal joints as disclosed in the patent
document I. Description is given of a conventional structure of one of yokes
constituting such cross shaft universal joints and including a basic structure to be
aimed at by the invention with reference to Figs. 9 to II E. A yoke I 0 of the
5 conventional structure is a so called press yoke which is formed by punching and
bending sequentially a metal plate such as steel material using a press, and includes a
base paii II and a pair of cmmecting arm parts 12, 12.
[0004]
The base part II has a partially-lacking cylindrical shape and includes a
10 discontinuous portion (slit) 13 for enabling expansion and compression of the inside
diameter of the base part II in one circumferential location thereof. It also includes
first and second flange pmiions 14, 15 while they are sandwiching the discontinuous
portion 13 fi"om both sides in the circumferential direction thereof. It further includes
a female serration 16 in the inner peripheral surface thereof. Also, because a metal
15 plate is folded back, the first and second flange pmtions 14, 15 have a double thickness
dimension of a metal plate. The first and second flange pmiions 14, 15 have a
through hole 17 and a screw hole 18 at the mutually matching positions of the first and
second flange potiions 14, 15 while the through hole 17 and the screw hole 18 are
respectively twisted with respect to the axis of the base pmi II. Also, in the free state
2 0 of the yoke I 0, the first and second flange potiions 14, 15 are substantially parallel to
each other, while the through hole 17 and screw hole 18 are arranged concentrically
with each other.
[0005]
The co1111ecting ann patis 12, 12 extend in the axial direction from such two
25 locations of the one axial end edge (in Fig. 9, upper end edge) of the base pmi II as are
2
opposed to each other in the diameter direction of the base pmt II. Also, the
arrangement direction (in Figs. 9 and 10, right and left direction) of the connecting arm
parts 12, 12 is circumferentially coincident (parallel to) with the arrangement direction
(in Fig. 10, right and left direction) of the first and second flange portions 14, 15.
5 And, the connecting arm pmts 12, 12 include mutually concentric circular holes 19, 19
in their respective tip portions.
[0006]
As shown in Fig. II A, the yoke I 0 having the above structure is made of a flat
material plate 22 which includes a base plate part 20 and a pair of tongue-like parts 21,
10 21. Firstly, the two ends of the base plate patt 20 of this material plate 22 are
respectively folded back 180° in their respective middle pmtions, thereby providing a
fu·st intermediate material 23 as shown in Fig. 11 B. Next, the first intermediate
material 23 is pressed between a pair of extrusion molding dies to be deformed
plastically, thereby providing a second intermediate material 24 as shown in Fig. II C.
15 In the second intermediate material24, the tongue-like pmts 2I, 21 to provide the pair
of connecting arm parts 12, 12 are curved in a pattially cylindrical manner, the base
end near portions of the tongue-like parts 21, 21 are bent substantially in a crank shape,
and the intermediate portions of the tongue-like parts 21, 2I to the tip end near portions
thereof are offset with respect to the base plate part 20. Next, of the thus-structured
2 0 second intermediate material 24, the central portion of the base plate part 20 is slightly
curved to provide a third intermediate material 25 as shown in Fig. liD. Next, the
base plate part 20 of the third intermediate material 25 is cmved further to provide a
fourth intermediate material 26 as sho\\~1 in Fig. II E. In this state, there are formed
the base part II and the pair of connecting ann parts 12, 12 to be equipped in the yoke
2 5 I 0 after completed. Finally, the tluough hole 17 and screw hole 18 are formed in the
3
first, second t1ange po1tions 14, 15 constituting the base pmt II, the female serration
16 is formed in the inner peripheral surface of the base pmt II, and the circular holes
19, 19 are formed in the connecting arm pmts 12, 12, thereby providing the yoke I 0 as
shown in Figs. 9 and 10.
5 [0007]
As shown in Figs. 12 to 14, to assemble a cross shaft universal joint using the
above-produced yoke 10, inside the circular holes 19, 19 formed in the tip portions of
the connecting arm parts 12, 12, there are pivotally supported the two ends of one shaft
palt 28a of a pair of shaft pmts 28a, 28b constituting a cross shaft 27. Thus, cup
1 0 bearings 29, 29 are internally engaged with and fixed to the insides of the circular
holes 19, 19.
[0008]
The cup bearings 29, 29 respectively correspond to shell-type needle bearings
and include bottomed cylindrical cups 30, 30 corresponding to shell-type outer rings,
15 and multiple needles 31, 31. And, while the cups 30, 30 are pressure insetted into the
circular holes 19, 19, the two ends of one shaft part 28a constituting the cross shaft 27
are respectively inserted into the radial-direction insides of the needles 31, 31. Thus,
the two ends of the shaft pmt 28a are rotatably suppmted on the yoke 10.
[0009]
20 Also, for assembling a steering apparatus, to connect and fix the base part 11
of the yoke 10 to the end of a rotation shaft constituted of any one of the steering shaft
2, intermediate shaft 4 and input shaft (see Fig. 7) in a torque transmittable manner,
firstly, the end of the rotation shaft is inserted into the inside of the center hole
(serration hole) of the base part 11, in the free state of the yoke 10. Thus, the female
25 serration 16 formed in the inner peripheral surface of the base part 11 is serration
4
'l
engaged with a male serration formed in the outer peripheral surface of the end of the
rotation shaft. Next, as shown in Figs. 12 and 13, a bolt 32 is insetted into the
through hole 17 and is threadedly engaged with the screw hole 18, and is fmther
tightened. Thus, the width of the discontinuous part 13 is elastically narrowed,
5 thereby reducing the diameter of the base part 11 elastically. As a result, the surface
pressure of the serration engaged pati increases, whereby the base end 11 is cmmected
and fixed to the end of the rotation shaft in a torque transmittable manner.
[0010]
In the yoke 10 having the above structure, for reason of securing the
1 0 assembling workability of the cup bearings 29, 29, the end of the shaft pmt 28a
constituting the cross shaft 27 is inserted into the radial-direction insides of the needles
31, 31 constituting the cup bearings 29, 29 with a certain degree of clearance.
Therefore, when in use, there is a possibility that the end of the shaft part 28a can
shake in the diameter direction (radial direction) relative to the cup bearings 29, 29 and
15 can generate strange sounds. Also, such shaking motion can probably become
excessively large with long use.
[00 11]
In view of the above circumstances, for example, the patent document 2
discloses an invention in which the peripheral part of a circular hole of a connecting
2 0 ann pmt, constituting a yoke, with a cup bearing being pressure inserted therein is
plastically deformed to thereby suppress occurrence of shaking motion between the
cup bearing and the shaft part of a cross shaft. Also, for example, the patent
document 3 discloses an invention in which the shape of a cup constituting a cup
bearing is worked (the cylindrical part thereof is deformed) to thereby suppress
2 5 occurrence of shaking motion between the cup bearing and the shaft part of a cross
5
5
shaft. However, in both of the inventions of the patent documents 2 and 3, for
suppression of occurrence of shaking motion, exclusive working on the connecting arm
part or cup is necessary. This inevitably increases the working cost of the cross shaft
universal joint.
Here, in the conventional structure shown in Figs. 9 to 14, the circumferential
phases of the arrangement direction of the pair of connecting arm parts 12, 12 and the
arrangement direction of the first, second flanges 14, 15 are identical with each other.
Thus, even when the first, second flanges 14, 15 are deformed in their mutually
approaching directions by tightening the bolt 32, as shown by a thick arrow in Fig. 14,
10 the connecting arm parts 12, 12 are simply flexually deformed in the mutually
15
20
approaching directions in the axial direction of the circular holes 19, 19 which is a
direction parallel to the arrangement direction of the first, second flange portions 14,
15; that is, there does not occur such defmmation as can reduce the above-mentioned
shaking motion.
RELATED ART REFERENCE
PATENT DOCUMENT
[0012]
Patent Document 1 :
Patent Document 2:
Patent Document 3:
JP-A-2012-37043
JP-A-2003-28188
JP-A-2007-327590
SUMMARY OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
25 [0013]
6
In view of the above circumstances, the invention aims at realizing at low
costs a yoke for a cross shaft universal joint which can suppress occurrence of shaking
motion between a bearing incorporated in a circular hole and the end of the shaft part
of a cross shaft rotatably supported by the bearing.
5
MEANS FOR SOLVING THE PROBLEMS
[0014]
A yoke for a cross shaft universal joint of the invention includes: a base part
for connecting and fixing the end of a rotation shaft thereto; and a pair of connecting
10 arm parts respectively extending in the axial direction from two diametrically opposite
positions corresponding to the base part at one axial end edge of the base part, wherein:
the pair of connecting arm patis include a pair of circular holes formed at tip portions
thereof to be concentric with each other, the pair of circular holes being configured to
pivotally support the end of a shaft pati, forming a cross shaft, through bearings; the
15 base pati has a partially-lacking cylindrical shape and includes a discontinuous part in
one circumferential location thereof; and the base part includes: a pair of flange parts
formed across the discontinuous part; and a pair of mounting holes formed in the
mutually matching pmiions of the pair of flange patis.
Here, the above-mentioned bearings are not limited to cup bearings (shell-type
2 0 needle bearings) but there can be employed various bearings such as a sliding bearing.
[0015]
Particularly, in the yoke for a cross shaft universal joint of the invention, the
circumferential phases of the arrangement direction (the axial direction of the axes of
the circular holes) of the pair of connecting arm patis and the arrangement direction
25 (the expansion direction of the discontinuous part) of the pair of flange parts are shifted
7
from each other (are arranged not in parallel to each other).
That is, an angle between the arrangement direction of the pair of connecting
ann parts and the arrangement direction of the pair of flange parts is set larger than
0° and smaller than 90° (preferably, larger than 10° and smaller than 60°, more
5 preferably, larger than 20° and smaller than 40°).
Also, the flange pmis are put nearer to each other up to a dimension capable of
fixing the end of the rotation shaft inside the base part, thereby applying mutually
approaching forces to the pair of connecting arm parts in directions inclined relative to
the axes of the pair of circular holes.
10 [0016]
In enforcing the above yoke for a cross shaft universal joint of the invention,
for example, the axes of the pair of mounting holes are set coincident with the
thickness direction of the pair of flange pmis.
In enforcing the above yoke for a cross shaft universal joint of the invention,
15 for example, the anangement direction of the circular holes and the arrangement
direction of the pair of connecting arm pmis are set coincident with each other, the
axial direction of the axes of the pair of mounting holes and the arrangement direction
of the pair of flange parts are set coincident with each other, and the axial direction of
the axes of the pair of circular holes and the axial direction of the axes of the pair of
2 0 mounting holes are shifted from each other in phase in the circumferential direction
(they are arranged not in parallel to each other).
Further, in enforcing the above yoke for a cross shaft universal joint of the
invention, for example, the mounting hole formed in one of the pair of flange parts is
constituted of a through hole, whereas the mounting hole formed in the other flange
2 5 pmi is constituted of a screw hole.
8
[0017]
Also, a method for manufacturing a yoke for a cross shaft universal joint of
the invention includes: forming a flat material plate including a base plate part
providing the base plate and a pair of tongue-like parts providing the pair of connecting
5 arm parts, the pair of tongue-like parts being arranged shifted from the length-direction
center thereof toward the length-direction one side thereof; folding back 180° the two
ends of the base plate part of the material plate with the same folding amounts to form
a first intermediate material; plastically deforming the first intermediate material such
that the pair of tongue-like parts are curved in pmtially cylindrical shapes, the base end
10 near portions of the pair of tongue-like parts are bent substantially in crank shapes, and
the intermediate portion near portions to the leading end near portions of the pair of
tongue-like pmts are offset with respect to the base plate part, thereby forming a
second intermediate material; curving the base plate pmt of the second intermediate
material to thereby form the base part and the pair of connecting arm pmts of the yoke;
15 and forming the pair of mounting holes in the pair of flange parts and the pair of
circular holes in the connecting arm parts.
[0018]
In enforcing the above yoke for a cross shaft universal joint of the invention,
for example, when the curving, the base pmt and pair of connecting arm pmts of the
2 0 yoke may also be formed in such a manner that the base plate part of the third
intermediate material is further curved after the central portion of the base plate pmt of
the second intermediate material is curved to form a third intermediate material.
ADVANTAGES OF THE INVENTION
25 [0019]
9
According to the above structured yoke for a cross shaft universal joint of the
invention, a structure capable of suppressing occurrence of shaking motion between
the bearings incorporated in the circular holes and the end of the shaft pati of the cross
shaft supported rotatably by the bearings can be realized at low costs.
5 That is, in the invention, since the circumferential phases of the arrangement
direction of the pair of connecting arm parts and the arrangement direction of the pair
of flange patis are shifted from each other, by tightening a fastening member such as a
bolt inserted through the mounting holes formed in the pair of flange patis to put the
flange parts nearer to each other, mutually approaching forces can be applied to the
10 pair of connecting arm parts in directions inclined relative to the axes of the pair of
circular holes. This can prevent formation of a radial clearance between the bearings
incorporated in the circular holes and the end of the shaft part of the cross shaft
inserted into the bearings, thereby enabling suppression of occurrence of shaking
motion between the bearings and the end of the shaft part. Also, in the invention,
15 since there is eliminated the need for exclusive working for suppression of such
shaking motion occurrence, the working cost of the yoke for a cross shaft universal
joint and thus a cross shaft universal joint including the yoke for a cross shaft universal
joint of the invention can be reduced, thereby enabling cost reduction.
[0020]
20 Also, according to the above-structured method for manufacturing a yoke for
a cross shaft universal joint of the invention, since the pair of tongue-like parts to
provide the pair of cotmecting arm patis are arranged shifted toward the
length-direction one side from the length-direction central portion of the base plate pati,
when forming the flat material plate, the finished yoke is formed such that the
2 5 circumferential phases of the arrangement direction of the pair of comtect ing arm patis
10
and the arrangement direction of the pair of flange parts are shifted from each other.
Thus, a structure capable of suppressing occurrence of shaking motion between the
bearings incorporated in the circular holes and the end of the shaft part of the cross
shaft supported rotatably by the bearings can be realized at low costs.
5
BRIEF DESCRIPTION OF THE DRAWINGS
[0021]
Fig. 1 is a side view of a yoke for a cross shaft universal joint according to a
first embodiment of the invention.
10 Fig. 2 is an end view of the yoke of Fig. 1 when viewed from below.
Figs. 3A to 3E are typical views of an example of a method for manufacturing
the yoke of Fig. 1, showing the sequence of the steps thereof.
Fig. 4 corresponds to Fig. 1 and shows how a cup bearing incorpomted in the
yoke supports a cross shaft.
15 Fig. 5 corresponds to Fig. 2 and shows a state where a bolt is fastened to the
yoke.
Fig. 6 is a section view of the yoke of Fig. 4, taken along the VI-VI line of Fig.
4.
Fig. 7 is a perspective view of an example of a steering apparatus with a
2 0 universal joint incorporated therein.
Fig. 8 is a partially sectional side view of an intermediate shaft with cross
shaft universal joints assembled to the two ends thereof.
Fig. 9 is a side view of a yoke having a conventional structure.
Fig. I 0 is an end view of the yoke of Fig. 9 when viewed from below.
25 Figs. 11A to liE are typical views of a method for manufacturing the yoke of
11
Fig. 9 having the conventional structure, showing the sequence of the steps thereof.
Fig. 12 corresponds to Fig. 9 and shows how a cup bearing incorporated in the
yoke supports a cross shaft.
Fig. 13 corresponds to Fig. I 0 and shows a state where a bolt is fastened to the
5 yoke.
Fig. 14 is a section view of the yoke of Fig. 12, taken along the XIV-XIV line
ofFig. 12.
MODES FOR CARRYING OUT THE INVENTION
10 [0022] [First Embodiment]
Figs. I to 6 show an example of a yoke for a cross shaft universal joint
according to a first embodiment of the invention. Here, the yoke I Oa of this
embodiment is characterized in that the circumferential phases of the arrangement
direction of a pair of connecting arm parts 12a, 12 and the an·angement direction of a
15 pair of first and second flange parts 14a, 15a are shifted from each other (arranged not
in parallel to each other). The structures and operations of the remaining parts thereof
are similar to those of the above-mentioned conventional structure of Figs. 9 to 14.
Therefore, the equivalent parts are given the same designations and thus the duplicated
description thereof is omitted or simplified. And, description is given below mainly
2 0 of parts not described above and the characteristic patts of this embodiment.
[0023]
The yoke 1 Oa of this embodiment is a so called press yoke to be formed by
enforcing punching and bending operations sequentially on a metal 'plate such as a
steel member using a press, and includes a base part lla and a pair of connecting arm
2 5 parts 12a, 12a.
12
[0024]
The base part lla has a partially lacking cylindrical shape which includes: a
discontinuous pm1 13a penetrating in the axial direction therethrough in one
circumferential location thereof; and the first and second flange parts 14a and 15a in
5 the two locations of the base part sandwiching the discontinuous part 13a from the two
circumferential sides. Since the metal plate is folded back, the first and second flange
pmts 14a and 15a each have a double thickness of a metal plate and respectively
include, in the mutually matching locations thereof, a through hole 17a and a screw
hole 18a formed concentrically with each other. Also, in this embodiment, the axes
10 of the through hole 17a and screw hole 18a are coincident with the thickness direction
of the first and second flange parts 14a and 15a.
[0025]
Also, the connecting arm pat1s 12a, 12a extend in the axial direction of the
base part lla from such two locations of the one axial end edge (in Figs. I and 4, upper
15 end edge) of the base part !Ia as exist on the mutually opposite sides in the diameter
direction of the base pat11la. And, the connecting arm pmts 12a, 12a include in the
tip pot1ions thereof two concentric circulm· holes 19a and 19a.
[0026]
Pmticularly, in this embodiment, the circumferential phases of the
20 arrangement direction {the X direction (right and left direction) of Figs. I, 2 and 6, and
the same direction as the axial direction XI of the axes of the first, second circular
holes 19a, 19a} of the connecting arm parts 12a, 12a and the arrangement direction
{the Y direction of Figs. 2, 6 and the same direction as the expansion direction of the
discontinuous part 13a and the axial direction Yl of the axes of the through hole 17a
2 5 and screw hole 18a} of the first and second flange parts 14a, 15a are shifted from each
13
other. In other words, the arrangement direction of the cmmecting ann pmts 12a, 12a
and the arrangement direction of the first, second flange pmts 14a, 15a are arranged not
in parallel to each other (and at a non-right angle). Specifically, the arrangement
direction of the first, second flange parts 14a, !Sa is set shifted (inclined), for example,
5 I 0 to 60° (in the illustrated example, 30°) from the arrangement direction of the
connecting arm parts 12a, 12a. Here, the shift amount (inclination angle) between the
two arrangement directions can be determined properly according to the shape of the
yoke lOa (pmticulm·ly, the rigidity size of the connecting arm parts 12a, 12a) and the
size of a radial clearance between a cup bearing 29 and the end of a shaft pmt 28a
1 0 (which are described later).
[0027]
Therefore, the circumferential phases of the axial direction XI of the axes of
the pair of circular holes 19a, 19a and the axial direction Yl of the axes of the tln·ough
hole 17a and screw hole 18a are shifted from each other. Specifically, the axial
15 direction Yl of the axes of the through hole 17a and screw hole 18a is set shifted
(inclined), for example, 10 to 60° (in the illustrated example, 30°) from the axial
direction XI of the axes of the pair of circular holes 19a, 19a.
[0028]
Also, as shown in Fig. 2, when viewed from below, that is, from the axial
2 0 direction of the rotation shaft, the axial direction XI of the axes of the pair of circular
holes 19a, 19a and the extension direction S of the discontinuous pmt 13a cross each
other at a non-right angle.
[0029]
As shown in Fig. 3A, the above-stmctured yoke I Oa of this embodiment is
2 5 made of a flat material plate 22a which, for example, includes a base plate pm·t 20a and
14
a pair of tongue-like parts 21a, 2la. In the material plate 22a, the tongue-like parts
21a, 2Ja are disposed shifted toward the length-direction one side (in Figs. 3A to 3E,
the right side) from the length-direction center of the base plate part 20a. Such
material plate 22a can be obtained, similarly to the material plate 22 formed according
5 to the conventional manufacturing method shown previously in Fig. llA, by punching
a metal plate between a punching die and a receiving die. The two ends of the base
plate part 20a of this material plate 22a are folded back 180° respectively, thereby
providing a first intermediate material 23a as shown in Fig. 3B. In this embodiment,
in the state of the material plate 22a, such portions of the base plate pmt 20a as project
10 toward both sides fi·om the tongue-like pmts 2la, 21a are different in length dimension
from each other, but the fold-back amounts of the two ends of the base plate part 20a
are set equal to each other. Next, the first intermediate material 23a is pressed
between a pair of pressing dies and is plastically deformed, thereby providing a second
intermediate material 24a as shown in Fig. 3C. In this second intermediate material
15 24a, the tongue-like pmts 2la, 2la thereof to provide the pair of cormecting arm parts
12a, 12a are curved in a pmtially cylindrical manner; and the base end near portions of
the tongue-like parts 2la, 2la are bent substantially in a crank shape and the
intermediate portion near portions of the tongue-like pmis 21a, 2la to the leading end
near pmtions thereof are offset with respect to the base plate pmt 20a. Next, in the
2 0 second intermediate material 24a, the central portion of the base plate part 20a is
slightly curved, thereby providing a third intermediate material 2Sa as shown in Fig.
3D. Then, the base plate part 20a of the third intermediate material 2Sa is curved
further, thereby providing a fomth intermediate material 26a as shown in Fig. 3E. In
this state, there are formed the base part 11 a and the pair of connecting arm parts 12a,
25 12a to be equipped in the completed yoke lOa. Finally, the through hole 17a and
15
screw hole 18a are formed in the first, second flanges 14a, 15a constituting the base
part II a, the female serration 16a is formed in the irn1er peripheral surface of the base
part lla, and the circular holes 19a, 19a arc formed in the connecting arm pmts 12a,
I 2a, respectively, thereby providing the yoke I Oa as shown in Figs. 1 and 2.
5 [0030]
As shown in Figs. 4 to 6, to assemble a cross shaft universal joint using the
above produced yoke 1 Oa, the two ends of one shaft pmt 28a of the pair of shaft parts
28a, 28b constituting the cross shaft 27 are pivotally suppmted on the insides of the
circular holes 19a, 19a formed in the tip portions of the connecting arm parts 12a, 12a.
10 Thus, the cup bearings 29, 29 are internally engaged with and fixed to the insides of
the circular holes 19a, 19a, respectively.
[0031]
The cup bearings 29, 29 respectively correspond to shell type needle bearings,
and include bottomed cylindrical cups 30, 30 corresponding to shell type outer rings
15 and multiple needles 31, 31. The cup 30 is formed by bending a hard metal plate
such as a carbon steel plate or a case hardened steel plate using plastic working such as
deep drawing, and includes a cylindrical pmt 33, a bottom pmt 34 and an inward flange
patt 35. The bottom part 34 covers the whole of the axial-direction one end side (in a
state where the cup bearing is assembled into the circular hole 19a, the outer surface
20 side of the corn1ccting arm pmt 12a) of the cylindrical part 33. Also, the inward
flange pmt 35 is arranged to be folded radially inward from the axial-direction other
end side (in a state where the cup bearing is assembled into the circular hole 19a, the
i1111er surface side of the corn1ccting arm pmt 12a) of the cylindrical part 33. And, the
above-structured cups 30, 30 arc pressure inse1ted into the circular holes 19a, 19a and,
2 5 of the outer surfaces of the cmmecting ann pmts 12a, 12a, the opening edges of the
16
circular holes 19a, 19a are plastically deformed radially inward to form caulking parts
(not shown), thereby preventing the cups 30, 30 from moving outwardly of the circular
holes 19a, 19a. Also, the two ends of the shaft part 28a constituting the cross shaft 27
are respectively inserted into the radial insides of the needles 31, 31. Thus, the two
5 ends of the shaft part 28a are rotatably supported with respect to the yoke 1 Oa. Here,
in the yoke 1 Oa of this embodiment as well, the ends of the shaft part 28a can be
insetted into the radial insides of the needles 31, 31 while having a certain degree of
clearance in a stage where the two ends of the shaft part 28a are inserted into the radial
insides of the needles 31, 31 (in a state before the bolt 32 is fastened), similarly to the
10 conventional sttucture. This prevents the assembling workability of the cup bearing
29, 29 fi·om being lowered.
[0032]
Also, to connect and fix the base patt 11 a of the yoke 10 of this embodiment
to the end of the rotation shaft in a torque transmittable mamter, the end of the rotation
15 shaft is insetted into the inside of the center hole (serration hole) of the base patt 11 a in
the free state of the yoke 1 Oa. Thus, the female serration 16a formed in the inner
peripheral surface of the base patt 11 a and a male serration formed in the outer
peripheral surface of the end of the rotation shaft are serration engaged with each other.
Next, as shown in Figs. 4 and 5, a bolt (a circular washer equipped bolt) 32 is insetted
2 0 through the through hole 17a and is threadedly engaged with the screw hole !Sa, and is
fastened fmther. Thus, since the width of the discontinuous patt 13a is elastically
narrowed (the first and second flange patts 14a and 15a are put nearer to each other),
the base part 11 a is elastically reduced 'in diameter. As a result, the surface pressure
of the serration engaged part increases, whereby the base part lla is connected and
2 5 fixed to the end of the rotation shaft in a torque transmittable manner.
17
[0033]
According to the above-stmctured yoke 1 Oa for a universal joint of this
embodiment, a structure capable of suppressing occunence of shaking motion between
the cup bearings 29, 29 assembled into the circular holes 19a, 19a and the end of the
5 shaft pm1 28a of the cross shaft 27 rotatably suppmted by the cup bearings 29, 29 can
be realized at low costs.
[0034]
That is, in this embodiment, smce the circumferential phases of the
arrangement direction X of the connecting ann parts 12a, 12a and the arrangement
1 0 direction Y of the first, second flange pat1s 14a, !Sa are shifted Jimn each other, by
tightening the bolt 32 to put the first, second flange pm1s 14a, !Sa nearer to each other,
as shown by thick anows in Fig. 6, mutually approaching forces having directions
inclined relative to the axes of the circular holes 19a, 19a can be applied to the
connecting arm pm1s 12a, 12a. Thus, due to the flexual deformation of the
15 connecting arm parts 12a, 12a caused by the forces applied, the cup bearings 29, 29
(the needles 31, 31 constituting the same) can be pressed against the two ends of the
shaft pm1 28a. More specifically, the radial-direction itmer surface of the needle 31
situated on the upper side of Fig. 6 of the needles 31, 31 constituting the cup bearing
29 arranged on the left side of Fig. 6 is pressed downward from above against the outer
2 0 peripheral surface of the left -side end of Fig. 6 of the two ends of the shaft part 28a;
and the radial-direction inner surface of the needle 31 situated on the lower side of Fig.
6 of the needles 31, 31 constituting the cup bearing 29 arranged on the right side of Fig.
6 is pressed upward fi·om below against the outer peripheral surface of the right -side
end of Fig. 6 of the two ends of the shaft part 28a. This can prevent formation of
2 5 radial-direction clearances between the cup bearings 29, 29 incorporated into the
18
insides of the circular holes 19a, 19a and the two ends of the shaft part 28a constituting
the cross shaft 27 inserted into the insides of the cup bearings 29, 29, thereby enabling
suppression of occurrence of shaking motion between the cup bearings 29, 29 and the
two ends of the shaft pmi 28a. Also, this embodiment eliminates the need for such
5 exclusive working to suppress occurrence of shaking motion as is found in the
inventions disclosed in the above-cited patent documents 2 and 3, thereby enabling
suppression of the working cost of the yoke 10 of this embodiment and thus a cross
shaft universal joint including the yoke I Oa of this embodiment, that is, enabling cost
reduction.
10 [003S]
Also, in this embodiment, the axial direction Xl of the axes of the pair of
circular holes 19a, 19a is set coincident with the arrangement direction X of the pair of
connecting arm paris 12a, 12a, the axial direction Yl of the axes of the through hole
17a and screw hole !Sa is set coincident with the arrangement direction Y of the first,
15 second flange paris 14a, !Sa, and the circumferential phases of the axial direction X 1
of the axes of the pair of circular holes 19a, 19a and the axial direction Yl of the axes
of the through hole 17a and screw hole !Sa are shifted fi·om each other. Therefore,
the pair of circular holes 19a, 19a and the through hole 17a, screw hole !Sa can be
formed in the circumferential-phase intermediate positions of the pair of comtecting
2 0 arm parts 12a, 12a and the first, second flange pmis 14a, !Sa, whereby, while
providing the above effects, the strengths of the pair of connecting ann patis 12a, 12a
and the first, second flange parts 14a, !Sa can be maintained in good balance.
[0036]
Also, according to a method for manufacturing the yoke 1 Oa for a cross shaft
2 5 universal joint of the embodiment having the above structure, since the pair of
19
tongue-like patis 21a, 21a providing the pair of cmmccting ann parts 12a, 12a arc
arranged in such positions of the base plate pati 20a as are shifted toward the
length-direction one side thereof from the length-direction center thereof when forming
the flat material plate 22a, the yoke 1 Oa after completed is formed such that the
5 circumferential phases of the arrangement direction of the connecting ann patis 12a,
12a and the arrangement direction of the first, second flange pmis 14a, !Sa are shifted
from each other. Thus, a structure capable of suppressing occurrence of shaking
motion between the cup bearings 29, 29 incorporated into the circular holes 19a, 19a
and the hvo ends of the shaft part 28a of the cross shaft 27 rotatably supported by the
10 cup bearings 29,29 can be realized at low costs.
[0037]
Here, the invention is not limited to the above embodiment but can be
changed or improved properly.
For example, the invention is not limited to the above embodiment in which
15 one of the mounting holes respectively formed in the pair of flange parts is formed as
the through hole and the other as the screw hole. For example, there may also be
employed a structure that the pair of mounting holes are respectively constituted of
through holes and a nut is pressure inserted into and fixed to one of them. Also, the
thickness dimension of the flange part is not limited to ·a double thickness dimension of
2 0 a metal plate used as a material plate.
[0038]
Also, the bearing to be incorporated into the circular hole formed in the
leading end of the connecting ann part is not limited to the cup bearing (shell type
needle bearing) but there may be employed various bearings such as a sliding bearing
2 5 having a shape omitting a needle from the cup bearing. Also, a method for
20
manufacturing a yoke for a universal joint according to the invention is not limited to
the method described in the embodiment. That is, another step(s) can be added
thereto, or any one or more of the above-mentioned steps can be omitted therefrom.
Or, other various methods can also be employed. Also, the invention is not limited to
5 the press yoke but can also apply to a forged yoke.
[0039]
This application is based on the Japanese Patent Application No. 2014-99166
filed on May 13, 2014 and the contents thereof are incorporated herein for reference.
10 DESCRIPTION OF REFERENCE NUMERALS AND SIGNS
[0040]
1: Steering wheel
2: Steering shaft
3: Universal joint
15 4: Intermediate shaft
5: Steering gear unit
6: Input shaft
7: Tie rod
8: Outer shaft
20 9: Inner shaft
10, lOa: Yoke
11, lla: Base part
12, 12a: Connecting arm part
13, l3a: Discontinuous part (slit)
25 14, 14a: First flange part
21
15, !Sa: Second flange part
I 6, I 6a: Female serration
17, I 7a: Through hole
I 8, I 8a: Screw hole
5 19, 19a: Circular hole
20, 20a: Base plate part
21, 21a: Tongue-like pmt
22, 22a: Material plate
23, 23a: First intermediate material
10 24, 24a: Second intermediate material
25, 25a: Third intermediate material
26, 26a: Fourth intermediate material
27: Cross shaft
28a, 28b: Shaft part
15 29: Cup bearing
30: Cup
31: Needle
32: Bolt
33: Cylindrical part
20 34: Bottom part
35: Inward flange part

CLAIMS
1. A yoke for a cross shaft universal joint, comprising:
a base part for connecting and fixing the end of a rotation shaft thereto; and
5 a pair of connecting arm pat1s respectively extending in the axial direction
from two diametrically opposite positions corresponding to the base patt at one axial
end edge of the base patt, wherein:
the pair of connecting arm parts include a pair of circular holes formed at tip
pmtions thereof to be concentric with each other, the pair of circular holes being
1 0 configured to pivotally support the end of a shaft pat1, forming a cross shaft, through
bearings;
the base pat1 has a pattially-lacking cylindrical shape and includes a
discontinuous part in one circumferential location thereof;
the base part includes: a pair of flange parts formed across the discontinuous
15 part; and a pair of mounting holes formed in the mutually matching pot1ions of the pair
of flange patts; and
the circumferential phases of the arrangement direction of the patr of
connecting arm patts and the arrangement direction of the pair of flange parts are
shifted from each other, and the flange parts are put nearer to each other up to a
2 0 dimension capable of fixing the end of the rotation shaft within the base pat1, thereby
applying mutually approaching forces to the pair of connecting arm patts in directions
inclined relative to the axes of the pair of circular holes.
2. The yoke for a cross shaft universal joint according to Claim 1,
25 wherein
23
the axes of the pair of mounting holes are coincident with the thickness
directions of the pair of flange parts.
3. The yoke for a cross shaft universal joint according to Claim I or 2,
5 wherein
the axial direction of the axes of the pair of circular holes is set coincident
with the arrangement direction of the pair of connecting arm parts, the axial direction
of the axes of the pair of mounting holes is set coincident with the arrangement
direction of the pair of flange parts, and the circumferential phases of the axial
1 0 direction of the axes of the pair of circular holes and the axial direction of the axes of
the pair of motmting holes are shifted from each other.
4. The yoke for a cross shaft universal joint according to any one of
Claims I to 3, wherein
15 when viewed from the axial direction of the rotation shaft, the axial direction
of the axes of the pair of circular holes and the extension direction of the discontinuous
part cross each other at non-right angles.
5. The yoke for a cross shaft universal joint according to any one of
2 0 Claims I to 4, wherein
the mounting hole formed in one of the pair of flange parts is a through hole,
while the mounting hole formed in the other is a screw hole.
6. A method for manufacturing a yoke for a cross shaft universal joint
2 5 including: a base part for connecting and fixing the end of a rotation shaft thereto; and
24
a pair of connecting arm pmis respectively extending in the axial direction from two
diametrically opposite positions corresponding to the base pmi at one axial end edge of
the base part, the pair of connecting arm parts including a pair of circular holes formed
at tip portions thereof to be concentric with each other, the pair of circular holes being
5 configured to pivotally support the end of a shaft part, forming a cross shaft, through
bearings; the base part having a partially-lacking cylindrical shape and including a
discontinuous part in one circumferential location thereof; the base part including: a
pair of flange parts formed across the discontinuous part; and a pair of mounting holes
formed in the mutually matching pmiions of the pair of flange parts, the method
1 0 comprising:
forming a flat material plate including a base plate part providing the base
plate and a pair of tongue-like pmis providing the pair of connecting arm parts, the pair
of tongue-like patis being shifted toward the length-direction one side of the base plate
part from the length-direction center thereof;
15 folding back 180° the two ends of the base plate pmi of the material plate in
the same folding amounts to form a first intermediate material;
plastically deforming the first intermediate material such that the pair of
tongue-like parts are curved in partially cylindrical shapes, the base end near potiions
of the pair of tongue-like parts are bent substantially in crank shapes, and the
2 0 intermediate pmiions of the pair of tongue-like parts to the leading end near portions
thereof are offset with respect to the base plate part, thereby forming a second
intermediate material;
curving the base plate part of the second intermediate material to thereby form
the base part and the pair of connecting arm patis of the yoke; and
25 forming the pair of mounting holes in the pair of flange parts and the pair of
25
5
circular holes in th~_eonnecting ann parts.
7. The method for manufacturing a yoke for a cross sha:ft universal joint
according to Claim 6, wherein
when the curving, the base plate patt of the third intermediate material 1s
further curved after the central portion of the base plate part of the second intermediate
material is curved to form a third intermediate material, thereby forming the base part
and the pair of cormecting arm parts of the yoke.