JP5120294B2 - 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, since the rotational torque applied to the intermediate shaft is increased, it is necessary to increase the coupling rigidity of the coupling portion between the intermediate shaft and the universal joint.

  The universal joint shown in Patent Document 1 extrudes a pilot hole for providing a bolt hole in a pair of flange parts extending in parallel with each other from a free end of a coupling cylinder part for fitting a shaft. A protruding portion is formed on the opposite side of. As a result, the bolt hole becomes longer by the amount corresponding to the protruding portion, and the flange portion is reinforced, so that the coupling rigidity between the coupling tube portion and the shaft is increased when the pair of flange portions are tightened with bolts.

  FIG. 7 shows a yoke 51 of a conventional universal joint having a folded portion that is folded inward after a pair of flange portions extend from the free end of the coupling tube portion in a substantially tangential direction of the coupling tube portion. FIG. 7A is a front view showing a conventional universal joint yoke 51, and FIG. 7B is a perspective view showing the conventional universal joint yoke 51.

  As shown in FIGS. 7 (1) and (2), bifurcated coupling arm portions 52, 52 are formed on the left side (left side of FIG. 7 (2)) of the yoke 51 of the conventional universal joint. The circular holes (bearing holes) 521 and 521 formed in the portions 52 and 52 are coupled to the other yoke 51 (not shown) via a cross shaft 7 inserted through a bearing.

  A substantially cylindrical coupling tube portion 53 is formed on the right side of the yoke 51 (the right side in FIG. 7 (2)), and the coupling tube is formed on the inner peripheral surface 531 of the coupling tube portion 53 from the right side in FIG. 7 (2). A cylindrical shaft (not shown) is inserted in parallel with the axial direction of the portion 53. 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. The extension ends of the tangential extension portions 544 and 544 are formed with folded portions 543 and 543 that are folded inward. The pair of left and right flange portions 54 and 54 are formed by the tangential extension portion 544 and the folded portion 543. ing. 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 the bolts 55 are formed concentrically 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. 7A is in contact with the lower surface of the bolt head 553 of the bolt 55. The seat surface 542 on the left side in FIG. 7A is in contact with the lower surface of the nut 551 that is screwed into the bolt shaft portion 552 of the bolt 55.

  The shaft is inserted into the inner peripheral surface 531 of the coupling cylinder portion 53, and the bolt 55 is inserted into the bolt holes 541 and 541 from the right side of FIG. When the nut 551 is screwed into the bolt shaft portion 552 of the bolt 55, the flange portions 54 and 54 are elastically deformed to narrow the groove width of the slit 56, and the outer peripheral surface of the shaft is strongly tightened with the inner peripheral surface 531 of the coupling tube portion 53. Can be fixed.

  The conventional universal joint shown in FIGS. 7A and 7B has improved rigidity because the flange portions 54 and 54 are thicker than the folded portions 543 and 543. However, since the joint surface between the tangential extension 544 and the folded portion 543 is only in partial contact and is not in close contact, when a large rotational torque acts on the universal joint, the tangential extension 544 and the folded portion 543 are folded back. The joint surface of the portion 543 may be displaced, and a large bending moment may act on the bolt 55.

Japanese Examined Patent Publication No. 3-75772

  It is an object of the present invention to provide a universal joint that can form a folded portion to improve the rigidity of the flange portion, reduce a bending moment generated in the bolt, and transmit a large rotational torque. .

The above problem is solved by the following means. That is, the first invention is a coupling cylinder part provided with an inner peripheral surface for fitting a shaft so as to be able to transmit rotational torque, a slit formed in the coupling cylinder part and penetrating through the inner peripheral surface, After forming a tangential extension extending substantially in the tangential direction of the coupling cylinder part from one and the other free ends of the coupling cylinder part across the slit, the folded part folded back inward at the extension end of the tangential extension part A pair of flange portions having a pair of coupling arm portions provided integrally with the coupling cylinder portion on the side opposite to the inner peripheral surface and having a bearing hole for supporting the cross shaft, and the pair of flange portions The bolt shaft portion is fitted into the formed concentric bolt hole, the slit interval between the pair of flange portions is narrowed, the inner peripheral surface of the coupling cylinder portion is reduced in diameter, and the outer peripheral surface of the shaft is Bolts to be tightened on the inner peripheral surface of the coupling cylinder are provided to make the plate material plastic The method for processing a universal joint which is molded by engineering, in order to prevent the displacement of the joint surface between the tangential extension and the folded portion of the flange portion which occurs when the effect is large rotational torque to the universal joint, the Extending the tangential direction by forming a pilot hole for forming a bolt hole on the outer side of the pair of flange parts and at the same time embossing a projecting part concentric with the lower hole on the inner side of the pair of flange parts is a processing method of a universal joint, characterized in that parts and by causing plastic flow of the metal material on the joint surface of the folded portion Ru are brought into close contact with the tangential extension and the folded portion.

  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.

  In the universal joint and the processing method thereof according to the present invention, a universal joint formed by plastic processing of a plate material, and a coupling cylinder portion having an inner peripheral surface for fitting a shaft so as to transmit rotational torque, A pair of flanges having a folded portion that is folded inward at the extended end of the tangential extension portion after forming a tangential extension portion extending in a substantially tangential direction of the coupled cylinder portion from one and the other free ends of the coupling cylinder portion By forming embossing to form a concentric projection with the lower hole at the same time as forming a pilot hole for forming a bolt hole on the outer side of the flange part and the pair of flange parts, The extension part and the folded part are in close contact. Therefore, the folded portion is formed to improve the rigidity of the flange portion, and the bending moment generated in the bolt can be reduced to transmit a large rotational torque.

It is the whole steering device provided with the universal joint of the example of the present invention. The blank of the board | plate material used as the material of the yoke of the universal joint of the Example of this invention is shown, (1) is a front view, (2) is a right view of (1). FIG. 2 shows a state in which the folded portion is formed on the blank of FIG. 2 and then embossed, (1) is a front view, (2) is a right side view of (1), and (3) is an A- of (1). It is A sectional drawing. (1) is the front view which shows the yoke which gave the plastic processing to the blank of FIG. 3, and was completed, (2) is a P arrow view of (1). (1) is BB sectional drawing of FIG. 4 (1), (2) is CC sectional drawing of FIG. 4 (2). It is DD sectional drawing of FIG. 4 (1). The conventional universal joint yoke is shown, (1) is a front view showing the conventional universal joint yoke, and (2) is a perspective view showing the conventional universal joint yoke.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall side view of a steering apparatus including a universal joint according to an 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 6 show a universal joint yoke according to an embodiment of the present invention, and show an example applied to a joint portion between one yoke 51 and the shaft 6 of the universal joint 5 shown in FIG. 2A and 2B show a blank 8 of a plate material used as the material of the universal joint yoke 51 according to the embodiment of the present invention. FIG. 2A is a front view and FIG. 2B is a right side view of FIG. 3 shows a state where embossing is performed after forming a folded portion on the blank 8 of FIG. 2, FIG. 3 (1) is a front view, FIG. 3 (2) is a right side view of FIG. FIG. 3 (3) is a cross-sectional view taken along the line AA in FIG. 3 (1).

  4 (1) is a front view showing a yoke 51 that has been molded by performing plastic working on the blank shown in FIG. 3, and FIG. 4 (2) is a view taken along arrow P in FIG. 4 (1). 5A is a cross-sectional view taken along the line BB in FIG. 4A, and FIG. 5B is a cross-sectional view taken along the line CC in FIG. FIG. 6 is a sectional view taken along the line DD of FIG. The universal joint of the present invention may be applied to a joint portion between the universal joint 4 and the male intermediate shaft 15 </ b> A in FIG. 1 or a joint portion between the universal joint 4 and the output shaft 23.

  2 to 6 show a coupling portion between one of the pair of yokes 51 and 51 constituting the universal joint 5 according to the embodiment of the present invention and the shaft 6. As shown in FIG. 2, a rectangular coupling cylinder portion 53 that is elongated in the vertical direction is formed at the right end of the blank 8 of the plate material used as the material of the yoke 51, and the coupling cylinder portion is formed on the upper and lower sides of the coupling cylinder portion 53. Rectangular flange portions 54 and 54 having the same width as the left and right widths of 53 are formed. In addition, on the left side of the coupling cylinder portion 53, coupling arm portions 52, 52 are formed to protrude to the left side with a space therebetween in the vertical direction.

  As shown in FIGS. 3 (1) and 3 (2), the flange portions 54 and 54 are folded inward (on the right side of FIG. 3 (2)) to form folded portions 543 and 543 by press working. Next, the flange portions 54 and 54 are embossed by using a press die composed of a punch 81 having two convex portions 811 and 811 and a die 82 having two concave portions 821 and 821. .

  By this embossing, pilot holes 57 and 57 for forming bolt holes are formed outside the tangential extension 544 of the flange portions 54 and 54 (the left side surface in FIGS. 3B and 3C). The At the same time, protrusions 58 and 58 concentric with the lower holes 57 and 57 are formed inside the folded portions 543 and 543 (on the right side surface of (FIGS. 3 (2) and (3)). The plastic flow of the metal material occurs on the joint surface 545 of the extension portion 544 and the folded portions 543 and 543, and the tangential extension portion 544 of the flange portions 54 and 54 and the joint surface 545 of the folded portions 543 and 543 are completely adhered.

  Next, the connecting cylinder part 53 of the blank 8 is formed into a cylindrical shape by press working, and the inner peripheral surface 531 of the connecting cylinder part 53 is machined. If the bolt holes and the seating surfaces are machined into the lower holes 57, 57, the forming of the yoke 51 of the universal joint according to the embodiment of the present invention is completed. That is, as shown in FIGS. 4 to 6, the yoke 51 of the universal joint according to the embodiment of the present invention is formed with the bifurcated coupling arm portions 52, 52, and the circle formed on the coupling arm portions 52, 52. The holes 521 and 521 are coupled to the other yoke 51 (not shown) via a cross shaft 7 (see FIG. 6) inserted through a bearing.

  The yoke 51 is formed with a substantially cylindrical coupling cylinder portion 53. An axis (pinion) is formed on the inner peripheral surface 531 of the coupling cylinder portion 53 from the left side of FIG. 4 (2) in parallel with the axial direction of the coupling cylinder portion 53. (Axis) 6 is inserted. The male serration formed on the outer peripheral surface of the shaft 6 is serrated to a female serration (not shown) formed on the inner peripheral surface 531 so that rotational torque can be transmitted.

  A pair of left and right flange portions 54, 54 having folded portions 543, 543 extending in the tangential direction from the coupling tube portion 53 and then folded inward are formed in the coupling tube portion 53 of the yoke 51. A slit (cut) 56 communicating with the inner peripheral surface 531 is formed between the protruding portions 58 and 58 of the folded portions 543 and 543.

  Bolt holes 541 and 541 for inserting the bolts 55 are formed concentrically in the flange portions 54 and 54. Further, seat surfaces 542 and 542 are formed on the tangential extension 544 of the flange portions 54 and 54. The seat surface 542 on the right side of FIG. 4A is in contact with the lower surface of the bolt head 553 of the bolt 55. The left seat surface 542 in FIG. 4A contacts the lower surface of the nut 551 that is screwed into the bolt shaft portion 552 of the bolt 55.

  The shaft 6 is inserted into the inner peripheral surface 531 of the coupling cylinder portion 53, and the bolt 55 is inserted into the bolt holes 541 and 541 from the right side of FIG. When the nut 551 is screwed into the bolt shaft portion 552 of the bolt 55, the flange portions 54 and 54 are elastically deformed to narrow the groove width of the slit 56, and the outer peripheral surface of the shaft 6 is strongly tightened with the inner peripheral surface 531 of the coupling tube portion 53. Can be fixed.

  The universal joint according to the embodiment of the present invention has improved rigidity because the flange portions 54 and 54 are increased in thickness by the folded portions 543 and 543. In addition, since the tangential extension portion 544 of the flange portion 54 and the joining surface 545 of the folded portion 543 are completely in close contact with each other, even if a large rotational torque acts on the universal joint, the tangential extension portion 544 and the folded portion 543 Since the joining surface 545 is not displaced, the bending moment generated in the bolt 55 is reduced, and a large rotational torque can be transmitted.

  In the above-described embodiment, the bolt holes 541 and 541 for inserting the bolts 55 are formed in the flange portions 54 and 54, but a female screw is formed in one bolt hole 541 and the bolt shaft portion of the bolt 55 is formed. The formed male screw may be screwed in. Although the example applied to the yoke of the universal joint 5 has been described in the above embodiment, the invention may be applied to the yoke of the universal joint 4 or may be applied 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 part 521 Circular hole (bearing hole)
53 Connecting cylinder portion 531 Inner peripheral surface 54 Flange portion 541 Bolt hole 542 Seat surface 543 Turn-up portion 544 Tangential direction extension portion 545 Joint surface 55 Bolt 551 Nut 552 Bolt shaft portion 553 Bolt head portion 56 Slit (cut)
57 Pilot hole 58 Projection 6 axis (pinion shaft)
7 Cross shaft 8 Blank 81 Punch 811 Convex part 82 Die 821 Concave part

Claims (3)

A coupling cylinder portion having an inner peripheral surface for fitting the shaft so that rotational torque can be transmitted;
A slit formed in the coupling cylinder and penetrating the inner peripheral surface;
After forming a tangential extension extending substantially in the tangential direction of the coupling cylinder part from one and the other of the free ends of the coupling cylinder part across the slit, the folded part is folded inward at the extension end of the tangential extension part A pair of flange portions,
A pair of coupling arm portions provided integrally with the coupling cylinder portion on the side opposite to the inner peripheral surface and having bearing holes for supporting the cross shaft,
The bolt shaft portion is fitted in concentric bolt holes formed in the pair of flange portions, the slit interval between the pair of flange portions is narrowed, and the inner peripheral surface of the coupling tube portion is reduced in diameter, A bolt for tightening the outer peripheral surface of the shaft with the inner peripheral surface of the coupling cylinder part,
In the method for processing a universal joint formed by plastic processing of a plate material ,
In order to prevent the displacement of the joint surface between the tangential extension portion of the flange portion and the folded portion, which occurs when a large rotational torque acts on the universal joint, a bolt hole is formed on the outside of the pair of flange portions. At the same time as forming the pilot hole, embossing is performed on the inner side of the pair of flanges to form a projecting part concentric with the pilot hole, so that the plastic flow of the metal material on the joint surface between the tangential extension and the folded part method for processing a universal joint, characterized in that the by causing Ru are brought into close contact with the tangential extension and the folded portion.   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 .

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