JP2007303575A - Cross shaft joint and vehicular steering device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cross shaft joint for preventing damage to shaft portions and rolling elements when mounting a cup bearing having the rolling elements inside on the shaft portions of a cross shaft, and to provide a vehicular steering device using the same. <P>SOLUTION: The cross shaft joint comprises the cross shaft 15 having four shaft portions 16, a plurality of the rolling elements 17 arranged on the outer peripheral face 16a of each shaft portion 16, and a bearing cup 18 covering the plurality of rolling elements 17 through the outer periphery side of the shaft portion 16. Into a tapered hole 22 formed at the shaft end face 16b of each shaft portion 16 with its diameter gradually enlarged toward the front end, a diameter enlarging member 23 is inserted for enlarging the diameter of the tapered hole 22 to form negative clearances in all of the plurality of rolling elements 17 between the outer peripheral face 16a of the shaft portion 16 and itself. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cross joint and a vehicle steering apparatus having the joint.

  For example, a rack and pinion type automobile steering apparatus includes a steering shaft having a steering member, a pinion shaft having pinion teeth constituting a rack and pinion mechanism, and an intermediate shaft interposed between the two shafts. The intermediate shaft is configured such that both end portions of the intermediate shaft are interlocked and connected to the respective end portions of the steering shaft and the pinion shaft by cross joints.

The cross shaft joint includes a cross shaft having four shaft portions projecting in all directions, a plurality of rolling elements arranged to be freely rollable on an outer peripheral surface of each shaft portion, and the plurality of rolling bodies connected to the shaft portion. And a bearing cup disposed coaxially with respect to the shaft portion in a state of being covered from the outer peripheral side.
In such a cross shaft joint, the shaft portion of the cross shaft may rattle in the axial direction or the radial direction, and noise may be generated. In order to solve this problem, between the bearing cup and the shaft portion of the cross shaft, There has been proposed a cross joint for interposing an engaging member to apply pressure in the axial direction and the radial direction to the cross shaft (see Patent Document 1).

  The cross shaft joint of Patent Document 1 corresponds to the end face of each shaft portion in a cross shaft joint that supports each shaft portion of the cross shaft via a needle roller by a bearing cup fitted in the corresponding fitting hole of the yoke. An engagement member that is interposed between the inner bottom surface of the bearing cup and that engages the bearing cup in a pressed state, and the engagement member engages with the first engaged portion of the inner bottom surface of the bearing cup in a concavo-convex manner. 1 engaging portion and a second engaging portion that engages with the second engaged portion on the end face of the shaft portion, and the engaging centers of the first and second engaging portions are offset from each other The engaged center of the first engaged portion is along the central axis of the bearing cup, and the engaged center of the second engaged portion is along the central axis of the shaft portion. One of the engaging portion and the second engaged portion includes a tapered convex portion, and the other includes a concave portion that fits into the convex portion. Includes a conical tapered surface that matches with each other about the center axis of the shaft portion. Thereby, since it can pressurize stably with respect to an axial part and an axial direction with respect to an axial part, a vibration and abnormal noise are eliminated to some extent. However, in this case, the radial pressing by the engaging member is in one direction, and a negative clearance can be achieved only in a part between the outer peripheral surface of the shaft portion and the plurality of rolling elements, so the transmission torque is large. In this case, there is a possibility that the rolling element having a positive clearance between the outer peripheral surface of the shaft portion may slip and cause rattling due to poor torque transmission or pulsation.

In order to solve this problem, for example, as shown in Patent Document 2, a cross joint having a negative clearance generated between all of the plurality of rolling elements and the outer peripheral surface of the shaft portion of the cross shaft has been proposed. ing.
As shown in FIG. 6, the assembly of the joint structure including the cross shaft joint of Patent Document 2 is performed in a state where the shaft portion 44 of the cross shaft 43 is inserted into the bearing hole 42 of the yoke 41. From outside in the axial direction, a bearing cup 46 having a plurality of rolling elements 45 arranged on the inner periphery is brought close to the shaft portion 44, and the rolling element 45 in the bearing cup 46 is pivoted while being pressed into the bearing hole 42 This is done by fitting from the tip of the portion 44. As a result, the diameter of the bearing cup 46 is reduced so that all of the rolling elements 45 are pressed against the shaft portion 44.

JP 2005-155830 A Table 03/064877

  However, when the rolling element 45 in the bearing cup 46 is fitted on the shaft portion 44, the bearing cup 46 is reduced in diameter by press-fitting into the bearing hole 42. Further, the corner portion 47 of the end surface of the shaft portion 44 is in strong contact with the outer peripheral surface of the shaft portion 44 serving as a rolling surface, and the rolling element 45 may be scratched or deformed. In particular, at the initial stage of fitting when the rolling element 45 comes into contact with the tip of the shaft part 44, the contact surface pressure between the rolling element 45 and the shaft part 44 is large, so that the tip of the shaft part 44 is easily damaged. As described above, when the rolling surface of the shaft portion 44 or the rolling element 45 is damaged, the performance and durability of the joint structure may be deteriorated.

  Accordingly, the present invention has been made in view of the above problems, and in a cross shaft joint of a type that generates a negative clearance between all of the plurality of rolling elements and the outer peripheral surface of the shaft portion of the cross shaft, An object of the present invention is to provide a cross joint and a vehicle steering apparatus having the joint that can prevent the shaft and rolling elements from being damaged when a bearing cup having an inner periphery is attached to the shaft of the cross. To do.

  In order to achieve the above object, a cross joint of the present invention includes a cross shaft having four shaft portions projecting in all directions, and a plurality of rolling elements arranged to be freely rollable on the outer peripheral surface of each shaft portion, In a cross joint including a bearing cup disposed coaxially with respect to the shaft portion in a state where the plurality of rolling elements are covered from the outer peripheral side of the shaft portion, the diameter gradually increases toward the tip side. In the tapered hole formed in the shaft end surface of each shaft part, the taper hole is expanded to generate a negative clearance between the outer peripheral surface of the shaft part for all of the plurality of rolling elements. The diameter-expanding member to be inserted is inserted.

  According to this configuration, when the bearing cup having the rolling element on the inner periphery is attached to the shaft portion, all of the plurality of rolling elements and the outer peripheral surface of the shaft portion are expanded by expanding the tapered hole of the shaft portion with the diameter increasing member. Since there is a negative clearance between the two, there is no need to generate a negative clearance when the bearing cup is inserted into the shaft, and the rolling element can be inserted without contacting the outer peripheral surface of the shaft. Therefore, damage to the tip of the shaft portion and the rolling element can be prevented.

Further, in this cross shaft joint, the plurality of rolling elements are made up of needle rollers in which a crowning conforming to the curved shape of the outer peripheral surface of each shaft portion after the diameter expansion of each shaft portion is formed on the outer peripheral surface. Is preferred.
According to this, the crowning formed on the outer peripheral surface of the needle roller conforms to the curved shape of the outer peripheral surface of the shaft portion after diameter expansion, so that the outer peripheral surface of the shaft portion contacts the outer peripheral surface of the needle roller. The surface pressure can be reduced.

The plurality of rolling elements may include needle rollers in which a partial crowning for reducing an edge load on each shaft portion is formed at an axial end portion of the outer peripheral surface.
Thereby, the stress concentration to the axial direction edge part of the outer peripheral surface of a needle roller can be prevented, and the contact surface pressure with respect to each axial part can be optimized.

In the cross joint, the bearing cup and the diameter-expanding member are preferably provided with positioning means for positioning both members coaxially.
The positioning means allows the bearing cup and the diameter-expanding member to be positioned coaxially without being eccentric, and the diameter-expanding member can uniformly expand the taper hole to the outer diameter side. Thus, a negative clearance between the outer peripheral surface of the shaft portion can be generated more reliably.

A vehicle steering apparatus according to the present invention includes a steering shaft having a steering member, a pinion shaft having pinion teeth constituting a rack and pinion mechanism, an intermediate shaft interposed between the two shafts, and the intermediate shaft. The cross shaft joint includes both ends connected to the steering shaft and each end of the pinion shaft.
According to this configuration, since the cross shaft joint is provided, it is possible to prevent the shaft portion and the rolling element from being damaged when the bearing cup having the rolling element on the inner periphery is attached to the shaft portion of the cross shaft. .

  According to the present invention, when a bearing cup having a rolling element on the inner periphery is attached to the shaft portion, all of the plurality of rolling elements and the outer peripheral surface of the shaft portion are expanded by expanding the tapered hole of the shaft portion with the diameter increasing member. Since there is a negative clearance between the two, there is no need to generate a negative clearance when the bearing cup is inserted into the shaft, and the rolling element can be inserted without contacting the outer peripheral surface of the shaft. Therefore, damage to the tip of the shaft portion and the rolling element can be prevented. Thereby, the quality of a cross-shaft joint can be improved and durability can be improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view of a vehicle steering apparatus having a cross joint of the present invention. The vehicle steering apparatus 1 includes a steering shaft 3 having one end connected to a steering member (steering wheel) 2 and one end connected to the other end of the steering shaft 3 via a cross joint 4 of the present invention. An intermediate shaft 5, a pinion shaft 6 connected to the other end of the intermediate shaft 5 via the cross joint 4 of the present invention, and a pinion tooth 6 a provided near the end of the pinion shaft 6. It has a rack bar 7 as a turning shaft that has matching rack teeth 7a and extends in the left-right direction of the automobile.

The pinion shaft 6 and the rack bar 7 constitute a rack and pinion mechanism as a steering mechanism. The rack bar 7 is supported in a housing 8 fixed to the vehicle body so as to be capable of linear reciprocation through a plurality of bearings (not shown). Both end portions of the rack bar 7 protrude to both sides of the housing 8, and tie rods 9 are coupled to the respective end portions. Each tie rod 9 is connected to a corresponding steered wheel 10 via a corresponding knuckle arm (not shown).
When the steering member 2 is operated and the steering shaft 3 rotates, this rotation is converted into a linear motion of the rack bar 7 along the left-right direction of the automobile by the pinion teeth 6a and the rack teeth 7a. Thereby, steering of the steered wheel 10 is achieved.

  FIG. 2 is a side view of the main part of the vehicle steering apparatus 1 of the present invention, and FIG. 3 is a cross-sectional view taken along the line III-III of FIG. In FIG. 2, an intermediate shaft 5 is interposed between the steering shaft 3, the pinion shaft 6, and both the shafts 3, 6, and both ends of the intermediate shaft 5 are connected to the steering shaft 3 and the pinion shaft 6. Each end portion is interlocked with a cross shaft joint 4.

A U-shaped first yoke 11 is provided at the end of the steering shaft 3, and the first yoke 11 has a pair of opposing arms 13 and 13. On the other hand, a U-shaped second yoke 12 is provided at one end of the intermediate shaft 5, and the second yoke 12 has a pair of opposed arms 14, 14. Then, bearing holes 13a and 13a having the same axis line are formed in the arms 13 and 13 of the first yoke 11, and bearing holes 14a having the same axis line in the arms 14 and 14 of the second yoke 12, respectively. , 14a are formed.
The cross joint 4 is fitted in the bearing holes 13a, 13a, 14a, 14a.

The cross shaft joint 4 includes a cross shaft 15 having four shaft portions 16 projecting in four directions, a plurality of rolling elements 17 disposed on the outer peripheral surface 16a of the shaft portion 16 so as to be freely rollable, and the plurality of rolling members. A bearing cup 18 is provided coaxially with respect to the shaft portion 16 in a state where the moving body 17 is covered from the outer peripheral side of the shaft portion 16.
In each of the bearing holes 13a, 13a, 14a, and 14a, the shaft portions 16 of the cross shaft 15 are rotated around the axis via the bearing cup 18 in which a plurality of rolling elements 17 are arranged on the inner periphery. It is supported freely. The structure between the third yoke 19 provided at the other end of the intermediate shaft 5 and the fourth yoke 20 provided at the end of the pinion shaft 6 is the same, and the description thereof is omitted.

FIG. 4 is an exploded cross-sectional view of the main part of the cross shaft joint 4, showing the main part of the cross shaft joint 4 in the arm 13 of the first yoke 11.
The cross shaft 15 includes a body portion 21 and four shaft portions 16 that protrude in four directions from the side peripheral surface of the body portion 21. The cross shaft 15 is made of steel, and the body portion 21 and the four shaft portions 16 are integrally formed by forging.
The rolling element 17 includes a needle roller having a crowning formed on the outer peripheral surface 17a that conforms to the curved shape of the outer peripheral surface 16a of each shaft portion 16 after the diameter of each shaft portion 16 is expanded. And the partial crowning for reducing the edge load with respect to each axial part 16 is formed in the axial direction edge part 17b of the outer peripheral surface 17a of the needle roller 17. As shown in FIG.
The bearing cup 18 has, for example, a bottomed cylindrical shape, and includes a cylindrical portion 18a and a disk portion 18b that is continuous with an end portion of the cylindrical portion 18a. And the internal peripheral surface of the cylindrical part 18a is used as the track surface. The needle roller 17 and the bearing cup 18 are made of steel.

A tapered hole 22 is formed in the shaft end surface 16 b of the shaft portion 16, and a diameter increasing member 23 is inserted into the tapered hole 22. The diameter-expanding member 23 expands the taper hole 22 to generate a negative clearance between the outer peripheral surface 16 a of the shaft portion 16 for all of the plurality of rolling elements 17.
The tapered hole 22 is formed in the shaft end surface 16b of the shaft portion 16 so as to gradually increase in diameter toward the tip side. That is, the tapered hole 22 includes a large-diameter opening 22a, a tapered surface 22b that gradually increases in diameter toward the distal end side, and a small-diameter bottom surface 25c.
The diameter-expanding member 23 is made of, for example, a metal (for example, steel) having an inverted frustoconical cross section. It is composed of
The diameter d1 of the opening 22a of the tapered hole 22 is smaller than the diameter d2 of the large-diameter end surface 23a of the enlarged member 23 so that a part of the enlarged member 23 is inserted into the tapered hole 22. The diameter d3 of the bottom surface portion 22c is set to be smaller than the diameter d4 of the small diameter end surface 23c of the diameter expanding member 23.

  The bearing cup 18 and the diameter expanding member 23 are provided with positioning means for positioning the members 18 and 23 coaxially. That is, a protrusion 24 is formed concentrically with the axis L of the shaft portion 16 on the large-diameter end surface 23 a of the diameter-expanding member 23, and the above-mentioned concentricity with the axis L of the shaft portion 16 is formed on the inner bottom surface 18 c of the bearing cup 18. A recess 25 is formed to engage with the protrusion 24 in an uneven manner.

  In the assembled state, the bearing cup 18 is in a state of being fitted into the bearing hole 13a of the arm 13 in the cylindrical portion 18a. Further, in the bearing cup 18, a diameter increasing member 23 for expanding the taper hole 22 is inserted into the taper hole 22 formed in each shaft portion 16. A negative clearance between all the moving bodies 17 and the outer peripheral surface 16a of the shaft portion 16 is generated.

FIGS. 5A and 5B are explanatory views for explaining an assembly method of the cross joint 4. FIG. 5A shows a state before the bearing cup 18 is inserted, and FIG. 5B shows a state in which the bearing cup 18 is being inserted. (C) has shown the state which the diameter-expansion member 23 is pressed and the taper hole 22 is diameter-expanding.
In assembling the cross shaft joint 4, first, the shaft portions 16, 16 in the same axial direction constituting the cross shaft 15 are set in the bearing holes 13 a, 13 a of the opposing arms 13, 13 of the first yoke 11. Then, the diameter-expanding member 23 is brought close to the shaft part 16 from the outside in the axial direction of the one shaft part 16, and the diameter-expanding member 23 is expanded along the tapered surface 22 b of the tapered hole 22 formed in the shaft part 16. A part of the member 23 is inserted. Then, the bearing cup 18 in which a plurality of needle rollers 17 are arranged along the inner circumference is brought close to the shaft portion 16 (see FIG. 5A), and the protrusion 24 of the diameter expanding member 23 and the recess 25 of the bearing cup 18 are The bearing cup 18 is press-fitted into the bearing hole 13a until they are engaged (see FIG. 5B). In this state, since the inner diameter d5 of the needle roller 17 is larger than the shaft diameter d6 of the shaft portion 16 (see FIG. 4), there is a gap between the plurality of needle rollers 17 and the outer peripheral surface 16a of the shaft portion 16. Then, the bearing cup 18 is pressurized toward the diameter expansion member 23 in a state where the inner bottom surface 18c of the bearing cup 18 is in contact with the large diameter end surface 23a of the diameter expansion member 23 (see FIG. 5C). As a result, the taper hole 22 can be expanded to generate a negative clearance between the outer peripheral surface 16 a of the shaft portion 16 for all of the plurality of needle rollers 17. Thereafter, the inner peripheral portion on the opening end side of the bearing hole 13a is caulked to prevent the bearing cup 18 from coming off. Similarly, in the bearing hole 13 a of the other arm 13, a bearing cup (not shown) in which a plurality of needle rollers 17 are arranged on the inner periphery is attached to the shaft portion 16.

  Before the assembly, an annular seal member 26 is attached in advance to the base end side of the shaft portion 16 of the cross shaft 15. Further, an annular flange 18e that is bent radially inward from the end of the cylindrical portion 18a is formed at the end of the bearing cup 18 on the opening side. The seal member 26 and the flange 18e come into contact with each other to prevent foreign matter from entering the needle roller 17 side.

  As described above, the taper hole 22 of the shaft portion 16 is expanded by the diameter expanding member 23 to generate a negative clearance between all of the plurality of rolling elements (needle rollers) 17 and the outer peripheral surface 16a of the shaft portion 16. Therefore, there is no need to generate a negative clearance when the bearing cup 18 is inserted into the shaft portion 16, and the rolling element 17 and the outer peripheral surface 16a of the shaft portion 16 can be inserted without contacting each other. Damage to the tip of the portion 16 and the rolling element 17 can be prevented.

  And in this cross shaft coupling 4, the crowning which fits the curved shape of the outer peripheral surface 16a of each said shaft part 16 after the diameter expansion of each shaft part 16 was formed in the outer peripheral surface 17a. Since it consists of a needle roller, the outer peripheral surface 16a of the axial part 16 can be made to follow the outer peripheral surface 17a of the needle roller 17, and a contact surface pressure can be made small. Moreover, since the partial crowning for reducing the edge load with respect to each axial part 16 is formed in the axial direction edge part 17b of the outer peripheral surface 17a of this needle roller 17, the axis | shaft of the outer peripheral surface 17a of the needle roller 17 is formed. Stress concentration on the direction end portion 17b can be prevented and the contact surface pressure with respect to each shaft portion 16 can be optimized.

  The cross joint 4 is provided with a protrusion 24 and a recess 25 as positioning means for positioning the members 18 and 23 coaxially on the bearing cup 18 and the diameter-expanding member 23, respectively. Thereby, the bearing cup 18 and the diameter-expanding member 23 are positioned coaxially without being eccentric, and the diameter-expanding member 23 can uniformly expand the taper hole 22 to the outer diameter side. The negative clearance between the outer peripheral surface 16a of the shaft portion 16 can be more reliably generated for all 17.

  Note that the cross joint of the present invention is not limited to the illustrated form, and may be of other forms within the scope of the present invention. In the above-described embodiment, the diameter-expanding member 23 is made of steel, but is not limited to steel. The diameter of the tapered hole 22 is increased and the outer circumference of the shaft portion 16 is increased with respect to all of the plurality of rolling elements 17. Any material may be used as long as it generates a negative clearance between the surface 16a. Further, as the positioning means, the protrusion 24 is formed on the diameter-expanding member 23 and the recess 25 is formed on the bearing cup 18. However, it is sufficient that the bearing cup 18 and the diameter-expanding member 23 can be positioned coaxially. It is also possible to form the recess 25 in the member 23 and form the protrusion 24 in the bearing cup 18.

It is a schematic diagram of the steering apparatus for vehicles which has the cross-axis coupling of this invention. It is a side view of the principal part of the steering device for vehicles of the present invention. It is sectional drawing in the III-III cross section of FIG. It is an exploded sectional view of an important section of a cross joint. It is explanatory drawing explaining the assembly method of a cross shaft coupling, (a) shows the state before inserting a bearing cup, (b) shows the state in the middle of inserting the bearing cup, (c) is The state which the diameter-expansion member is pressed and the taper hole is expanding is shown. It is explanatory drawing explaining the assembly of the joint structure provided with the conventional cross shaft joint.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle steering device 3 Steering shaft 4 Cross shaft joint 5 Intermediate shaft 6 Pinion shaft 11 1st yoke 13 Arm 13a Bearing hole 15 Cross shaft 16 Shaft part 17 Rolling body (needle roller)
18 Bearing cup 23 Diameter-expanding member 24 Projection (positioning means)
25 Recess (Positioning means)

Claims (5)

A cross shaft having four shaft portions projecting in all directions, a plurality of rolling elements arranged to roll on the outer peripheral surface of each shaft portion, and the plurality of rolling bodies covered from the outer peripheral side of the shaft portion In a cross joint having a bearing cup arranged coaxially with respect to the shaft in the state,
An outer peripheral surface of the shaft portion with respect to all of the plurality of rolling elements by expanding the taper hole into a tapered hole formed in the shaft end surface of each shaft portion so that the diameter gradually increases toward the tip side. A cross-shaft joint, wherein a diameter-expanding member that generates a negative clearance is inserted.   2. The cross shaft joint according to claim 1, wherein each of the plurality of rolling elements includes a needle roller having a crowning formed on an outer peripheral surface that conforms to a curved shape of an outer peripheral surface of each shaft portion after the diameter of each shaft portion is expanded. .   3. The cross joint according to claim 1, wherein each of the plurality of rolling elements includes a needle roller in which a partial crowning for reducing an edge load on each of the shaft portions is formed at an axial end portion of an outer peripheral surface. .   The cross shaft joint according to any one of claims 1 to 3, wherein a positioning means is provided on the bearing cup and the diameter-expanding member to position both members coaxially. A steering shaft having a steering member;
A pinion shaft having pinion teeth constituting a rack and pinion mechanism;
An intermediate shaft interposed between these two shafts,
5. A vehicle steering apparatus comprising: the cross shaft joint according to claim 1, wherein both ends of the intermediate shaft are interlocked and connected to the respective ends of the steering shaft and the pinion shaft.

Images