JP5636828B2 - Universal joint and processing method thereof - Google Patents

Description

  The present invention relates to a universal joint, and more particularly, to a universal joint that connects shafts that transmit rotation of a steering shaft of a steering device, and a processing method thereof.

  In a steering device that steers the front wheels of a vehicle, the movement of a steering shaft that is rotated by the operation of a steering wheel is transmitted to an input shaft of a steering gear through a universal joint.

  The movement of the steering wheel is transmitted to the steering gear via a steering shaft and an intermediate shaft that are rotatably provided in the steering column, and the direction of the wheel is steered by the steering gear. Usually, the steering shaft and the input shaft of the steering gear cannot be provided on the same straight line.

  For this reason, conventionally, an intermediate shaft is provided between the steering shaft and the input shaft to the steering gear, the end of the intermediate shaft and the steering shaft, and the end of the intermediate shaft and the end of the input shaft of the steering gear. Are coupled via a universal joint so that power can be transmitted between the steering shaft and the input shaft that do not exist on the same straight line.

  In recent years, there has been an increasing number of column assist type electric power steering devices in which an assist device for applying a steering assist force to a steering shaft is provided between an intermediate shaft and a steering wheel.

  In such column assist type electric power steering, the rotational torque applied to the intermediate shaft increases, so the rigidity of the universal joint, especially the rigidity of the coupling arm around the bearing hole for supporting the cross shaft. Need to be larger.

  The universal joints shown in Patent Document 1 and Patent Document 2 are formed with an annular protrusion around the bearing hole on the radially inner side of the coupling arm portion to increase the axial length for axially supporting the bearing. The rigidity of the coupling arm portion around the bearing hole for supporting the shaft is increased.

  However, in the universal joints shown in Patent Literature 1 and Patent Literature 2, the cross-sectional shape of the coupling arm portion in the direction orthogonal to the axis of the coupling cylinder portion is flat. If the cross-sectional shape of the coupling arm portion is flat, plastic processing from the plate material is easy, but in order to improve the rigidity of the coupling arm portion, it is necessary to increase the width dimension of the coupling arm portion. Therefore, since the amount of interference with the other coupling arm portion connected by the cross shaft increases, it is difficult to increase the bending angle of the universal joint.

  It is preferable to press the convex surface on the radially outer side of the coupling arm portion inward in the radial direction to plastically flow the metal material and increase the thickness of the coupling arm portion because the rigidity of the coupling arm portion is improved. However, since the metal material also plastically flows on the outer peripheral surface side of the coupling arm portion, the outer peripheral surface side of the coupling arm portion expands, and the shape of the outer peripheral surface is not stable. Since the machining of the inner peripheral surface of the bearing hole and the coupling cylinder portion is performed by clamping the outer circumferential surface of the coupling arm portion, the clamping accuracy is not stable, and the machining accuracy is adversely affected.

  The universal joint machining method disclosed in Patent Document 3 improves the drilling accuracy of the bearing hole by simultaneously drilling the bearing hole with a punch and chamfering the coupling arm portion. However, the universal joint processing method disclosed in Patent Document 3 does not stabilize the shape of the outer peripheral surface of the coupling arm portion when the radially outer side of the coupling arm portion is pressed radially inward.

Japanese translation of PCT publication No. 2002-540357 Japanese Utility Model Publication No.59-8015 JP-A-8-270669

  The present invention provides a universal joint in which the shape of the outer peripheral surface of the coupling arm portion is molded stably when the radially outer side of the coupling arm portion is pressed inward in the radial direction, and a processing method therefor. Let it be an issue.

The above problem is solved by the following means. That is, the first invention is provided integrally with the coupling cylinder part on the opposite side of the coupling cylinder part and coupled cylinder part for coupling the shaft so as to be able to transmit rotational torque. A cross-sectional shape in a direction perpendicular to the axis has a circular arc shape protruding outward in the radial direction, and a pair of coupling arm portions having bearing holes for supporting the cross shaft, and formed by plastic processing of the plate material A method of processing a universal joint, wherein the cross-sectional shape in a direction perpendicular to the axis of the coupling cylinder portion of the coupling arm portion forms a convex surface having an arc shape radially outward and a concave surface radially inward; A step of forming the coupling cylinder portion into a cylindrical shape, and the pair of
Fold tangential extensions extending in the tangential direction from each of the coupling cylinders with coupling arms
A folding forming step for forming a pair of flange portions, a small-diameter through-hole forming step for forming a small-diameter through hole having a smaller diameter than the bearing hole and substantially concentric with the bearing hole in the pair of coupling arm portions, and the small-diameter penetration The outer peripheral surfaces of the pair of coupling arm portions in which the holes are formed are constrained by a mold, and the convex surfaces on the radially outer side of the pair of coupling arm portions are pressed radially inward to cause the metal material to plastically flow, and the pair of couplings A projecting portion forming step for forming a projecting portion that is concentric with the bearing and larger in diameter than the bearing hole on the concave surface on the radially inner side of the arm portion, and a small diameter through hole of the pair of coupling arm portions is expanded to a predetermined diameter. It is the processing method of the universal joint characterized by having the bearing hole shaping | molding process which forms this bearing hole in this order.

The second invention is a universal joint processed by the universal joint processing method of the first invention.

Third invention is a steering apparatus having a universal joint of the second invention.

Fourth invention, in the processing method of the universal joint of the first or second th one of the invention, binding method of the coupling tubular portion and shaft, welding, caulking, coupling sleeve the outer peripheral surface of the shaft A method for processing a universal joint, wherein the method is any one of bolt tightening tightened on an inner peripheral surface of a portion.

  In the universal joint and the processing method thereof according to the present invention, a small diameter through hole forming step of forming a small diameter through hole having a smaller diameter than the bearing hole and substantially concentric with the bearing hole in the pair of coupling arms, and a pair of the small diameter through holes formed A binding arm that forms a pair of coupling arms by restraining the outer peripheral surface of the coupling arm with a mold and pressing the radially outer convex surfaces of the pair of coupling arms inward in the radial direction to plastically flow the metal material. A part forming step and a bearing hole forming step of forming a bearing hole having a predetermined diameter by expanding the small-diameter through holes of the pair of coupling arm portions.

  The plastic flowed metal material flows to the small diameter through hole side, the small diameter through hole is reduced in diameter, and the outer peripheral surface of the coupling arm portion is accurately formed into a predetermined shape. Accordingly, the clamping accuracy when the outer peripheral surface of the coupling arm portion is clamped during machining is stabilized, and the machining accuracy is improved.

It is a whole side view of a steering device provided with the universal joint of Example 1 of the present invention. It is a perspective view which shows the yoke of the universal joint of Example 1 of this invention. The state which formed the return | turnback part and the joint arm part in the yoke of the universal joint of Example 1 of this invention is shown, (a) is a front view, (b) is a P arrow view of (a). It is AA sectional drawing of Fig.3 (a). The state which formed the small diameter through-hole in a pair of joint arm part of the yoke of the universal joint of Example 1 of this invention is shown, (a) is a front view, (b) is Q arrow view of (a). . It is BB sectional drawing of Fig.5 (a). After the outer peripheral surfaces of the pair of coupling arm portions of the universal joint yoke according to the first embodiment of the present invention are constrained by a mold, the projecting portions are projected radially inwardly on the concave surfaces on the radially inner side of the pair of coupling arm portions. (A) is a front view, (b) is an R arrow view of (a). It is CC sectional drawing of Fig.7 (a). The state which formed the bearing hole in a pair of coupling arm part of the yoke of the universal joint of Example 1 of this invention is shown, (a) is a front view, (b) is a S arrow view of (a). It is DD sectional drawing of Fig.9 (a). It is a perspective view which shows the yoke of the universal joint of Example 2 of this invention.

  Hereinafter, Example 1 to Example 2 of the present invention will be described with reference to the drawings.

  Embodiments of the present invention will be described below with reference to the drawings. 1 is an overall side view of a steering apparatus including a universal joint according to a first embodiment of the present invention. As shown in FIG. 1, a steering apparatus having a universal joint according to an embodiment of the present invention has a steering shaft 12 on which a steering wheel 11 can be mounted on the rear side of the vehicle body (right side in FIG. 1), and the steering shaft 12 is inserted. The steering column 13, an assist device (steering assisting portion) 20 for applying an assist torque to the steering shaft 12, and a rack / pinion mechanism (not shown) on the front side of the vehicle body (left side in FIG. 1) of the steering shaft 12 And a steering gear 30 connected to each other.

  The steering shaft 12 is spline-fitted between a female steering shaft 12A and a male steering shaft 12B so as to be able to transmit rotational torque and to be relatively movable in the axial direction. Therefore, when the female steering shaft 12A and the male steering shaft 12B collide, the spline fitting portion moves relative to each other so that the total length can be shortened.

  The cylindrical steering column 13 inserted through the steering shaft 12 combines an outer column 13A and an inner column 13B so as to be telescopically movable. Therefore, the steering column 13 has a so-called collapsible structure in which, when an impact in the axial direction is applied during a collision, the entire length is reduced while absorbing energy due to the impact.

  The vehicle body front side end portion of the inner column 13B is press-fitted and fixed to the vehicle body rear side end portion of the gear housing 21. Further, the front end portion of the male steering shaft 12B on the vehicle body is passed through the inside of the gear housing 21 and connected to the rear end portion of the assist device 20 on the rear side of the input shaft (not shown).

  The steering column 13 is supported by a support bracket 14 at a middle portion thereof on a part of the vehicle body 18 such as a lower surface of the dashboard. Further, a locking portion (not shown) is provided between the support bracket 14 and the vehicle body 18, and when an impact in a direction toward the front side of the vehicle body is applied to the support bracket 14, the support bracket 14 is locked to the locking bracket 14. It moves away from the vehicle and moves to the front side of the vehicle.

  The upper end portion of the gear housing 21 is also supported on a part of the vehicle body 18. In the case of this embodiment, by providing a tilt mechanism and a telescopic mechanism, the position of the steering wheel 11 in the longitudinal direction of the vehicle body and the height position can be freely adjusted. Such a tilt mechanism and a telescopic mechanism are well known in the art and are not characteristic features of the present invention, and thus detailed description thereof is omitted.

  The output shaft 23 protruding from the front end face of the gear housing 21 on the vehicle body is connected to the rear end portion of the intermediate shaft 15 via a universal joint (upper universal joint) 4. Further, a pinion shaft (hereinafter referred to as a shaft) 6 of the steering gear 30 is connected to the front end portion of the intermediate shaft 15 via another universal joint (lower universal joint) 5. The intermediate shaft 15 is fitted on the vehicle body front side of the male intermediate shaft (male shaft) 15A on the vehicle body rear side of the female intermediate shaft (female shaft) 15B so as to be able to transmit rotational torque and relatively move in the axial direction. Is fitted.

  A pinion (not shown) is formed at the lower end (front end of the vehicle body) of the shaft 6. A rack (not shown) meshes with the pinion, and rotation of the steering wheel 11 moves the tie rod 31 to steer a wheel (not shown).

  A case 261 of an electric motor 26 is fixed to the gear housing 21 of the assist device 20, and a worm is coupled to a rotating shaft (not shown) of the electric motor 26. A worm wheel (not shown) is attached to the output shaft 23, and the worm of the rotating shaft of the electric motor 26 is engaged with the worm wheel.

  A torque sensor (not shown) is provided around the intermediate portion of the output shaft 23. The direction and magnitude of the torque applied from the steering wheel 11 to the steering shaft 12 is detected by a torque sensor, and the electric motor 26 is driven in accordance with the detected value via a reduction mechanism comprising a worm and a worm wheel. Then, the output shaft 23 is caused to generate auxiliary torque with a predetermined magnitude in a predetermined direction. The assist device that generates the auxiliary torque is not limited to an electric type, and may be a hydraulic assist device.

  2 to 10 show a universal joint yoke according to the first embodiment of the present invention, and show an example in which the yoke is applied to a joint portion between one yoke 51 and the shaft 6 of the universal joint 5 shown in FIG. FIG. 2 is a perspective view showing the yoke of the universal joint according to the first embodiment of the present invention. FIGS. 3 to 10 show the forming process of the universal joint yoke 51 according to the first embodiment of the present invention, and FIG. 3 shows a state in which the folded portion and the coupling arm portion are formed on the universal joint yoke according to the first embodiment of the present invention. (A) is a front view, (b) is a P arrow view of (a). 4 is a cross-sectional view taken along line AA in FIG.

  5A and 5B show a state in which a small-diameter through hole is formed in a pair of coupling arm portions of the universal joint yoke according to the first embodiment of the present invention. FIG. 5A is a front view, and FIG. FIG. 6 is a cross-sectional view taken along the line BB in FIG. FIG. 7 shows a configuration of the universal joint yoke according to the first embodiment of the present invention. The state formed by projecting is shown, (a) is a front view, (b) is a view taken along the arrow R in (a). FIG. 8 is a cross-sectional view taken along the line CC of FIG. 9A and 9B show a state in which bearing holes are formed in a pair of coupling arm portions of the universal joint yoke according to the first embodiment of the present invention. FIG. 9A is a front view, and FIG. is there. FIG. 10 is a sectional view taken along the line DD of FIG.

  FIGS. 2 to 10 show a coupling portion between one of the pair of yokes 51 and 51 constituting the universal joint 5 according to the first embodiment of the present invention and the shaft 6. As shown in FIG. 2, bifurcated coupling arm portions 52, 52 are formed on the left side of the universal joint yoke 51 (left side in FIG. 2), and bearing holes 521 formed in the coupling arm portions 52, 52, 521 is coupled to the other yoke 51 (not shown) via a cross shaft 7 inserted through a bearing.

  A substantially cylindrical coupling cylinder part 53 is formed on the right side of the yoke 51 (right side in FIG. 2). The coupling cylinder part 53 is formed on the inner peripheral surface 531 of the coupling cylinder part 53 from the right side in FIG. The shaft 6 is inserted in parallel. The male serration formed on the outer peripheral surface of the shaft is serrated to a female serration (not shown) formed on the inner peripheral surface 531 so that rotational torque can be transmitted.

  Tangential extension portions 544 and 544 extending in the tangential direction from the coupling cylinder portion 53 are formed in the coupling cylinder portion 53 of the yoke 51. Folded portions 543 and 543 that are folded inward are formed at the extended ends of the tangential extension portions 544 and 544, and a pair of left and right flange portions 54 and 54 are formed by the tangential extension portion 544 and the folded portion 543. Yes. A slit (cut) 56 communicating with the inner peripheral surface 531 is formed between the flange portions 54, 54. The slit 56 is formed over the entire length of the coupling cylinder portion 53 in the axial direction.

  Bolt holes 541 and 541 for inserting bolts (not shown) are concentrically formed in the flange portions 54 and 54. In addition, seat surfaces 542 and 542 are formed on the flange portions 54 and 54. The right seat surface 542 in FIG. 2 is in contact with the lower surface of the bolt head of the bolt. The left seat surface (not shown) in FIG. 2 is in contact with the lower surface of a nut (not shown) screwed into the bolt shaft portion of the bolt.

  A shaft is inserted into the inner peripheral surface 531 of the coupling cylinder portion 53, and bolts are inserted into the bolt holes 541 and 541 from the right side of FIG. When the nut is screwed into the bolt shaft portion of the bolt, the flange portions 54 and 54 are elastically deformed and the groove width of the slit 56 is narrowed, and the outer peripheral surface of the shaft is firmly tightened and fixed by the inner peripheral surface 531 of the coupling tube portion 53 Can do.

As shown in FIGS. 2 to 4 , the bifurcated coupling arm portions 52, 52 have a circular arc shape in which the cross-sectional shape in the direction orthogonal to the axis of the coupling cylinder portion 53 is convex radially outward by pressing . Convex surfaces 522 and 522 are formed on the radially outer side of the coupling arm portions 52 and 52, and concave surfaces 523 and 523 are formed on the radially inner side of the coupling arm portions 52 and 52. Moreover, as shown in FIG.2 and FIG.3, the connection cylinder part 53 is shape | molded by the press work to a cylindrical shape. Further, the tangential extension portions 544 and 544 are folded inward to form folded portions 543 and 543.

  Next, as shown in FIGS. 5 and 6, a small-diameter through hole 525 having a smaller diameter than the bearing hole 521 is formed substantially concentrically with the bearing hole 521 with a punch (not shown). Next, as shown in FIGS. 7 and 8, the outer peripheral surfaces 526 and 526 of the coupling arm portions 52 and 52 are restrained by the mold 8.

With the outer peripheral surfaces 526 and 526 constrained by the mold 8, as shown in FIGS. 7 and 8, with the punch (not shown), the convex surfaces 522 and 522 on the radially outer side of the coupling arm portions 52 and 52 are radially inward. The metal material is plastically flowed by pressing. Since the die (not shown) is brought into contact with the concave surfaces 523 and 523 on the radially inner side, the protrusions 58 are formed on the concave surfaces 523 and 523 on the radially inner side so as to protrude radially inward. The protrusion 58 is concentric with the bearing holes 521 and 521 and has a larger diameter than the bearing holes 521 and 521.

  Since the outer peripheral surfaces 526 and 526 of the coupling arm portions 52 and 52 are constrained by the mold 8, the surplus of the plastic material that has flowed plastically flows to the small diameter through hole 525 side, and the small diameter through hole 525 is reduced in diameter. The outer peripheral surfaces 526 and 526 of the coupling arm portions 52 and 52 are accurately formed into a predetermined shape.

  Next, as shown in FIGS. 9 and 10, the reduced diameter through hole 525 is machined to increase the diameter, and bearing holes 521 and 521 having predetermined diameters are formed in the coupling arm portions 52 and 52. Moreover, if the inner peripheral surface 531 of the coupling cylinder portion 53 is machined, the forming of the yoke 51 of the universal joint according to the first embodiment of the present invention is completed. The machining of the bearing holes 521 and 521 and the inner peripheral surface 531 of the coupling cylinder portion 53 is performed by clamping the outer peripheral surfaces 526 and 526 of the coupling arm portions 52 and 52, but the outer peripheral surface 526 of the coupling arm portions 52 and 52 is processed. Since 526 is accurately formed into a predetermined shape, the clamping accuracy is stabilized and the machining accuracy is improved.

  Further, as shown in FIG. 2, a part of the protruding portion 58 (the left end side in FIG. 2) at the tip of the coupling arm portions 52, 52 is scraped vertically, and an opening 59 is formed in a part of the bearing holes 521, 521. , 59 is preferable because the cross shaft 7 can be easily assembled to the bearing holes 521 and 521. Furthermore, as shown in FIG. 2, if the oblique chamfered portions 524 and 524 are formed at the upper and lower ends of the concave surfaces 523 and 523 of the coupling arm portions 52 and 52, respectively, the bending angle of the universal joint can be further increased. It becomes possible.

  In the universal joint according to the first embodiment of the present invention, the coupling arm portions 52 and 52 have a circular arc shape in which the cross-sectional shape in the direction orthogonal to the axis of the coupling cylinder portion 53 is convex radially outward. Since the rigidity is improved even if the width dimensions of 52 and 52 are small, the amount of interference with the other coupling arm portion connected by the cross shaft 7 is small, and the bending angle of the universal joint can be increased. In addition, since the protruding portion 58 is formed so as to protrude inward in the radial direction and the axial length for supporting the bearing is increased, the support rigidity of the bearing is increased.

  FIG. 11 is a perspective view showing a yoke of a universal joint according to Embodiment 2 of the present invention. In the following description, only structural portions and operations different from those of the first embodiment will be described, and overlapping descriptions will be omitted. The same parts as those in the first embodiment will be described with the same numbers. As shown in FIG. 11, in the second embodiment of the present invention, the coupling cylinder portion 53 has no flange portion for reducing the diameter of the coupling cylinder portion 53, and the shaft 6 and the coupling cylinder portion 53 are welded or They are joined by caulking.

  In the first embodiment, the bolt holes 541 and 541 for inserting bolts are formed in the flange portions 54 and 54, but a female screw is formed in one bolt hole 541 and formed in the bolt shaft portion of the bolt. You may screw in a male screw. Moreover, in the said Example, although the example applied to the yoke of the universal joint 5 was shown, you may apply to the yoke of the universal joint 4, and you may apply to both yokes of the universal joints 5 and 4. .

DESCRIPTION OF SYMBOLS 11 Steering wheel 12 Steering shaft 12A Female steering shaft 12B Male steering shaft 13 Steering column 13A Outer column 13B Inner column 14 Support bracket 15 Intermediate shaft 15A Male intermediate shaft 15B Female intermediate shaft 18 Car body 20 Assist device 21 Gear housing 23 Output shaft 26 Electric Motor 261 Case 30 Steering gear 31 Tie rod 4 Universal joint (upper universal joint)
5 Universal joint (lower universal joint)
51 Yoke 52 Coupling arm portion 521 Bearing hole 522 Convex surface 523 Concave surface 524 Chamfered portion 525 Small diameter through hole 526 Outer peripheral surface 53 Coupling tube portion 531 Inner peripheral surface 54 Flange portion 541 Bolt hole 542 Seat surface 543 Folded portion 544 Slit direction extending portion 544 (Cutting)
58 Projection 59 Opening 6 Axis (Pinion Shaft)
7 Cross shaft 8 Mold

Claims (4)

A coupling cylinder for coupling the shafts so as to be able to transmit rotational torque;
On the opposite side of the connecting cylinder part, it is provided integrally with the connecting cylinder part, and the cross-sectional shape in the direction orthogonal to the axis of the connecting cylinder part has a circular arc shape protruding radially outward, and the cross shaft is pivotally supported. A pair of coupling arm portions having bearing holes for
A processing method of a universal joint formed by plastic processing of a plate material,
A step of forming an arcuate convex surface on the radially outer side and a concave surface on the radially inner side of a cross-sectional shape of the coupling arm portion in a direction perpendicular to the axis of the coupling cylinder portion;
Forming the coupling cylinder part into a cylindrical shape;
A tangential extension extending in a tangential direction from each coupling cylinder having the pair of coupling arms.
A folding forming step of folding the inside to form a pair of flange portions,
A small-diameter through-hole forming step of forming a small-diameter through hole having a smaller diameter than the bearing hole in the pair of coupling arm portions and substantially concentric with the bearing hole;
The outer peripheral surfaces of the pair of coupling arm portions in which the small-diameter through holes are formed are constrained by a mold, and the metal material is plastically flowed by pressing the radially outer convex surfaces of the pair of coupling arm portions radially inwardly.
A projecting portion forming step of forming a projecting portion concentric with the bearing on the radially inner concave surface of the pair of coupling arm portions and having a larger diameter than the bearing hole;
A bearing hole forming step of forming a bearing hole of a predetermined diameter by expanding the small diameter through hole of the pair of coupling arm portions,
A processing method of a universal joint, characterized by having in this order.   A universal joint machined by the universal joint machining method according to claim 1.   A steering apparatus having the universal joint according to claim 2. In the processing method of the universal joint according to claim 1,
A method for processing a universal joint, characterized in that the connecting method of the connecting tube portion and the shaft is any one of welding, caulking, and bolt tightening for tightening the outer peripheral surface of the shaft with the inner peripheral surface of the connecting tube portion.

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