JP2009210012A - Universal joint and its processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a universal joint in which it is possible to transmit a large running torque by reducing a bending stress generating in a bolt, reducing an average stress generating in the bolt and enlarging an allowable stress vibration amplitude. <P>SOLUTION: Flange parts 54A, 54B are elastically deformed by holding from longitudinal direction of the fig. 3 with clamping fixtures 71 for machining and the change of shapes corresponding to the conditions in which a male serration 61 of the shaft 6 is fastened by a female serration 531 are generated in the flange part 54A and 54B. In this state, on the flange part 54A, 54B, bolt holes 541A and 541B are perforated, and a seat surface 542A of the flange part 54A and the seat surface 542B of the flange part 54B are machined. As a result, the bolt hole 541A, 541B are (concentrically) formed on the same axis line and against the axis line of the bolt hole 541A, 541B seat surface 542A and seat surface 542B are orthogonally formed. <P>COPYRIGHT: (C)2009,JPO&INPIT

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. Normally, 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 joints shown in Patent Document 1 and Patent Document 2 form a slit over the entire axial length of the coupling tube portion of the yoke, thereby facilitating elastic deformation of the coupling tube portion, and integral with the coupling tube portion across the slit. When the pair of flange portions provided on the bolt are tightened with bolts, the coupling rigidity between the coupling cylinder portion of the yoke and the shaft is increased.

  14 to 16 show a conventional universal joint in which a slit is formed over the entire axial length of the coupling cylinder portion of the yoke, and FIG. 14 (1) is a perspective view showing the conventional universal joint, and FIG. ) Is a longitudinal sectional view of FIG. FIG. 15 is an enlarged cross-sectional view taken along the line CC of FIG. 14 (2) showing a state before a bolt is tightened on a conventional universal joint. FIG. 16 (1) is an enlarged cross-sectional view taken along the line CC of FIG. 14 (2) showing a state in which the bolt is tightened on the conventional universal joint, and FIG. 16 (2) is a view when the bolt is tightened on the conventional universal joint. It is a parts figure showing a bolt simple substance.

  As shown in FIGS. 14 to 15, bifurcated coupling arm portions 52, 52 are formed on the left side of the yoke 51 (FIG. 14), and circular holes 521, 521 formed in the coupling arm portions 52, 52 are formed in the circular holes 521, 521. The other yoke 51 is coupled via a cross shaft (not shown) inserted through a bearing.

  A substantially cylindrical coupling cylinder portion 53 is formed on the right side (FIG. 14) of the yoke 51, and the coupling cylinder portion 53 is formed on the female serration 531 formed on the inner peripheral surface of the coupling cylinder portion 53 from the right side of FIG. The shaft 6 is inserted in parallel to the axial direction. The male serration 61 formed on the outer peripheral surface of the shaft 6 is serrated to the female serration 531 so that rotational torque can be transmitted.

  The coupling cylinder part 53 of the yoke 51 is formed with a pair of left and right flange parts 54A and 54B that extend in the tangential direction from the coupling cylinder part 53 and then bend inward. A slit (cut) 56 communicating with the female serration 531 is formed between the flange portions 54A and 54B. The slit 56 is formed over the entire length of the coupling cylinder portion 53 in the axial direction.

  An annular recess 62 is formed at a substantially intermediate position in the axial direction of the male serration 61 of the shaft 6. Therefore, when the shaft 6 tries to come out from the coupling cylinder portion 53 of the yoke 51 to the right side in FIG. 14, the bolt shaft portion 552 of the bolt 55 comes into contact with the concave portion 62 and the shaft 6 comes out of the coupling cylinder portion 53 of the yoke 51. To prevent.

  Bolt holes 541A and 541B for inserting the bolts 55 are concentrically formed in the flange portions 54A and 54B. Further, a seating surface 542A and a seating surface 542B are formed on the flange portions 54A and 54B. The seating surface 542A contacts the lower surface 553A of the bolt head 553 of the bolt 55. The seating surface 542B contacts the lower surface 551A of the nut 551 that is screwed into the male screw 552A of the bolt shaft portion 552 of the bolt 55. The bolt holes 541A and 541B are formed on the same axis (concentric), and the seat surface 542A and the seat surface 542B are formed orthogonal to the axis of the bolt holes 541A and 541B.

  As shown in FIG. 16 (1), the shaft 6 is inserted into the female serration 531 of the coupling cylinder portion 53, and the bolt 55 and the spring washer 554 are inserted into the bolt holes 541A and 541B from the right side of FIG. When the nut 551 is screwed into the male screw 552A of the bolt 55, the flange portions 54A and 54B are elastically deformed to narrow the groove width of the slit 56, and the male serration 61 of the shaft 6 can be firmly tightened and fixed with the female serration 531.

  The flange portions 54A and 54B are elastically deformed to narrow the groove width of the slit 56, and the seating surface 542A and the seating surface 542B have a shape (non-parallel) narrowed by an angle β on the lower side of FIG. Therefore, since the seating surface 542A and the seating surface 542B are inclined with respect to the axis of the bolt holes 541A and 541B, both the bending stress and the tensile stress act on the bolt 55. As a result, the stress at the substantially central portion of the axial length of the bolt shaft portion 552 of the bolt 55 is increased, the allowable stress amplitude is decreased, and the bolt 55 is liable to be subject to fatigue failure, so that a large rotational torque is transmitted. It becomes difficult.

JP-A-10-205547 JP 2000-192982 A

  It is an object of the present invention to provide a universal joint that can reduce bending stress generated in a bolt, reduce an average stress generated in the bolt, increase an allowable stress amplitude, and transmit a large rotational torque. And

  The above problem is solved by the following means. That is, the first invention is formed in the coupling cylinder part having an inner peripheral surface for fitting the shaft so that rotational torque can be transmitted to the proximal end portion, and formed in the coupling cylinder part. A through slit, a pair of flange portions provided integrally with the connecting cylinder portion across the slit, provided integrally with the connecting cylinder portion on the side opposite to the inner peripheral surface, and supports the cross shaft A pair of coupling arm portions having bearing holes for inserting the shafts, the shafts having outer peripheral surfaces that are inserted into the inner peripheral surface of the coupling cylinder portion and are fitted into the inner circumferential surface of the coupling cylinder portion so as to transmit rotational torque, A bolt shaft portion is fitted in a concentric bolt hole formed in the flange portion, the interval between the pair of flange portions is narrowed, the inner peripheral surface of the coupling tube portion is reduced in diameter, and the shaft Bolts that tighten the outer peripheral surface with the inner peripheral surface of the coupling cylinder, The bolt is formed such that the bolt hole is perpendicular to the seating surface of the flange portion that contacts the lower surface of the bolt head in a state where the peripheral surface is tightened by the inner peripheral surface of the coupling cylinder portion. It is a joint.

  According to a second invention, in the universal joint of the first invention, a female serration is formed on the inner peripheral surface of the coupling cylinder portion, and the male serration that engages with the female serration and transmits rotational torque is the above-described A universal joint formed on the outer peripheral surface of the shaft.

  A third invention is a steering device having the universal joint according to any one of the first to second inventions.

  4th invention is formed in the coupling cylinder part provided with the inner peripheral surface for fitting a shaft so that rotational torque can be transmitted to the part near a base end, and is formed in the coupling cylinder part, and penetrates the inner peripheral surface A pair of flange portions provided integrally with the coupling cylinder portion with the slit interposed therebetween, and provided integrally with the coupling cylinder portion on the side opposite to the inner peripheral surface, for pivotally supporting the cross shaft A pair of coupling arm portions having bearing holes, a shaft having an outer peripheral surface that is inserted into an inner peripheral surface of the coupling cylinder portion and is fitted to the inner circumferential surface of the coupling cylinder portion so as to transmit rotational torque, and the pair of flange portions A bolt shaft portion is internally fitted in a concentric bolt hole formed in the outer peripheral surface of the shaft, the inner peripheral surface of the coupling tube portion is reduced in diameter by narrowing a gap between the pair of flange portions. In a universal joint provided with a bolt that tightens the inner cylindrical surface of the coupling cylinder, The bearing surface of the flange portion that contacts the lower surface of the bolt head with the deformation corresponding to the state in which the outer peripheral surface of the shaft is fastened to the inner peripheral surface of the coupling cylinder portion applied to the pair of flange portions And the bolt hole is machined into the pair of flange portions.

  The universal joint according to the present invention is formed in a coupling cylinder portion having an inner circumferential surface for fitting a shaft to a proximal end portion so that rotational torque can be transmitted, and the coupling cylinder portion, and penetrates the inner circumferential surface. A slit, a pair of flange portions provided integrally with the coupling cylinder portion across the slit, and a bearing hole provided integrally with the coupling cylinder portion on the opposite side to the inner peripheral surface and for supporting the cross shaft Formed on a pair of flange portions, a shaft having an outer peripheral surface that is inserted into an inner peripheral surface of the coupling cylinder portion and is fitted inside the inner circumferential surface of the coupling cylinder portion so as to be able to transmit rotational torque, and a pair of flange portions The bolt shaft portion is fitted in the concentric bolt hole formed, the 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 connected to the coupling cylinder portion. Bolts to be tightened on the inner peripheral surface, and the bolts are tightened and the outer peripheral surface of the shaft is tightened to the inner peripheral surface of the coupling cylinder , Seat and the bolt hole of the flange portion abutting against the lower surface of the bolt head is formed so as to be orthogonal.

  Therefore, when the bolt is tightened, the bolt hole is formed on the same axis, and since the bearing surface of the flange portion is orthogonal to the axis of the bolt hole, only the tensile stress acts on the bolt, and the bending stress is almost not. Does not work. As a result, the average stress generated in the bolt can be reduced and the allowable stress amplitude can be increased, so that a large rotational torque can be transmitted.

  Embodiments 1 to 4 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. FIG. 2 is a longitudinal sectional view showing a state in which a bolt hole and a seating surface are processed in the universal joint according to the first embodiment of the present invention. 3 is a cross-sectional view taken along the line AA in FIG. FIG. 4 is a view corresponding to FIG. 3 showing a state in which the clamp of the universal joint after the processing of the bolt hole and the seat surface is released. FIG. 5 is a view corresponding to FIG. 3 showing a state in which the bolt is fastened to the universal joint according to the first embodiment of the present invention.

  As shown in FIG. 1, the steering device equipped with the universal joint according to the first 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 5 show the universal joint according to the first embodiment of the present invention, and show an example in which the universal joint 5 shown in FIG. 1 is applied to a coupling portion between one yoke 51 and the shaft 6. 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.

  FIGS. 2 to 5 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. Bifurcated coupling arm portions 52, 52 are formed on the left side of the yoke 51 (FIG. 2), and are inserted into circular holes 521, 521 formed in the coupling arm portions 52, 52 via bearings (not shown). It is connected to the other yoke 51 via a cross shaft. Therefore, the rotational force can be transmitted between the yokes 51 and 51 even if the centers of the yokes 51 and 51 are not located on the same straight line.

  A substantially cylindrical coupling cylinder portion 53 is formed on the right side (FIG. 2) of the yoke 51, and the coupling cylinder portion 53 is formed on the female serration 531 formed on the inner peripheral surface of the coupling cylinder portion 53 from the right side of FIG. The shaft 6 is inserted in parallel to the axial direction. The male serration 61 formed on the outer peripheral surface of the shaft 6 is serrated to the female serration 531 so that rotational torque can be transmitted.

  As shown in FIGS. 2 to 3, the coupling cylinder portion 53 of the yoke 51 is formed with a pair of left and right flange portions 54 </ b> A and 54 </ b> B that extend in the tangential direction from the coupling cylinder portion 53 and then bend inward. . A slit (cut) 56 communicating with the female serration 531 is formed between the flange portions 54A and 54B. The slit 56 is formed over the entire length of the coupling cylinder portion 53 in the axial direction.

  An annular recess 62 is formed at a substantially intermediate position in the axial direction of the male serration 61 of the shaft 6. Therefore, when the shaft 6 tries to come out from the coupling cylinder portion 53 of the yoke 51 to the right side in FIG. 2, the bolt shaft portion 552 of the bolt 55 comes into contact with the recess 62 and the shaft 6 comes out of the coupling cylinder portion 53 of the yoke 51. To prevent.

  Bolt holes 541A and 541B for inserting the bolts 55 into the flange portions 54A and 54B are formed by the following processing method. That is, the shaft 6 having the male serration 61 or the shaft 6 as a processing jig having the same shape as the shaft 6 is inserted into the female serration 531 of the coupling cylinder portion 53 and engaged with the serration.

  Next, the flange portions 54A and 54B are clamped from the left and right directions of FIG. 3 by the processing clamp jig 71, the flange portions 54A and 54B are elastically deformed, and the male serration 61 of the shaft 6 is tightened by the female serration 531. Corresponding deformation is applied to the flange portions 54A and 54B. That is, in the normal assembly state, the bolt 55 is tightened, and deformation corresponding to the state where the male serration 61 of the shaft 6 is tightened by the female serration 531 is applied to the flange portions 54A and 54B.

  In this state, the bolt holes 541A and 541B, the seat surface 542A of the flange portion 54A, and the seat surface 542B of the flange portion 54B are processed in the flange portions 54A and 54B. The seating surface 542A of the flange portion 54A abuts on the lower surface 553A of the bolt head 553 of the bolt 55. The bearing surface 542B of the flange portion 54B contacts the lower surface 551A of the nut 551 that is screwed into the male screw 552A of the bolt shaft portion 552 of the bolt 55. As a result, the bolt holes 541A and 541B are formed on the same axis (concentric), and the seat surface 542A and the seat surface 542B are formed orthogonal to the axis of the bolt holes 541A and 541B.

  Bolt holes 541A and 541B are processed with a drill 72, a seating surface 542A of the flange portion 54A is processed with a counterbore bit 73, and a seating surface 542B of the flange portion 54B is processed with a counterbore bit 74. The seating surface 542B of the flange portion 54B may be processed from the same side as the counterbore bit 73 using a counterbore bit (not shown).

  Although not shown in the drawings, as another example, the nut 551 is not used, a bolt hole (buck hole) 541A is formed in one flange portion 54A, and a bolt hole (female screw) is formed in the other flange portion 54B. The present invention may be applied to a screw bolt system in which the male screw 552A of the shaft portion 552 is screwed into the female screw and the flange portions 54A and 54B are tightened.

  In the case of this screw bolt method, the processing of the seating surface 542B of the other flange portion 54B is not required, and the flange portion 54A has a bolt hole 541A, the flange portion 54B has a bolt hole (female screw), and the flange portion 54A has a seating surface 542A. Will be processed.

  FIG. 4A shows a state where the yoke 51 that has finished the processing of the bolt holes 541A, 541B and the seating surfaces 542A, 542B is removed from the processing clamp jig 71. FIG. As shown in FIG. 4A, since the elastic deformation of the flange portions 54A and 54B is restored, the groove width of the slit 56 is widened, and the seat surface 542A and the seat surface 542B are formed at an angle θ on the lower side of FIG. Expanded shape.

  In order to assemble the yoke 51 thus manufactured to the vehicle body, as shown in FIG. 4 (2), the shaft 6 is inserted into the female serration 531 of the coupling cylinder portion 53, and the bolt holes 541A and 541B are inserted with the shaft shown in FIG. The bolt 55 and the spring washer 554 are inserted from the right side. When the nut 551 is screwed into the male screw 552A of the bolt 55, the flange portions 54A and 54B are elastically deformed to narrow the groove width of the slit 56 and the male serration 61 of the shaft 6 is firmly tightened with the female serration 531 as shown in FIG. Can be fixed.

  As a result, the bolt holes 541A and 541B are arranged on the same axis (concentric), and the seat surface 542A and the seat surface 542B are orthogonal to the axis of the bolt holes 541A and 541B. Acts, and bending stress hardly acts. As a result, the average stress generated in the bolt 55 is reduced and the allowable stress amplitude can be increased, so that a large rotational torque can be transmitted.

  Next, a second embodiment of the present invention will be described. FIG. 6 shows a coupling structure of a universal joint and a shaft according to a second embodiment of the present invention, and is a longitudinal sectional view showing a state in which a shaft is being press-fitted into the universal joint. FIG. 6 (2) is a cross-sectional view of FIG. FIG. FIG. 7 shows a coupling structure of a universal joint and a shaft according to the second embodiment of the present invention, and is a longitudinal sectional view showing a state in which the press-fitting of the shaft to the universal joint is completed. FIG. 7 (2) is a diagram of FIG. It is Q section expansion longitudinal cross-sectional view.

  FIG. 8 is a perspective view showing two examples of the coupling ring used in the coupling structure of the universal joint and the shaft according to the second embodiment 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. Further, the same parts will be described with the same numbers.

  The second embodiment shows a modification of the coupling structure between the yoke 51 of the universal joint 5 and the shaft 6. The coupling structure of the second embodiment includes a coupling portion between the universal joint 4 and the male intermediate shaft 15A, a coupling portion between the universal joint 4 and the output shaft 23, a coupling portion between the universal joint 5 and the female intermediate shaft 15B, and The present invention can be applied to any male shaft and female shaft coupling portion that fit together.

  That is, in Example 2, in order to transmit the rotational torque between the male shaft and the female shaft, non-circular processing such as serration that requires accuracy is unnecessary, and only by pressing the female shaft into the male shaft, An example of a coupling structure that enables the transmission of rotational torque and the axial movement of the female shaft relative to the male shaft to be disabled is shown.

  As shown in FIG. 6 (1), a cylindrical coupling cylinder 57 is formed on the right side (FIG. 2) of the yoke 51, and a cylindrical hole 571 is formed on the inner peripheral surface of the coupling cylinder 57. ing. A shaft 6 is inserted into the cylindrical hole 571 from the right side of FIG. 6 in parallel to the axial direction of the coupling cylinder portion 57, and a small-diameter columnar shaft portion 63 formed on the left outer peripheral surface of the shaft 6 is cylindrically shaped. It fits in the hole 571. In order to facilitate the easy insertion of the columnar shaft portion 63 of the shaft 6 into the cylindrical hole 571, the cylindrical hole 571 and the columnar shaft portion 63 are preferably fitted with an appropriate clearance fit. Or close fit.

  A thin cylindrical portion 573 is formed on the right end surface 572 of the coupling cylinder portion 57, and the thin cylindrical portion 573 protrudes to the right side by α (see FIG. 6 (2)) from the right end surface 572 of the coupling cylinder portion 57. Yes. The shaft 6 is formed with an annular groove 64 having a rectangular cross section on the right side of the small-diameter cylindrical shaft portion 63, and a cylindrical medium-diameter shaft having a slightly larger diameter than the cylindrical shaft portion 63 on the right side of the annular groove 64. A portion 65 is formed.

  A cylindrical large-diameter shaft portion 66 having the same diameter as the outer peripheral surface 574 of the coupling cylinder portion 57 is formed on the right side of the medium-diameter shaft portion 65. A coupling ring 58 is interposed between the left end surface 67 of the large-diameter shaft portion 66 and the right end surface 572 of the coupling cylinder portion 57. As shown in detail in FIG. 8, the coupling ring 58 has an annular cross-sectional shape. In the example of FIG. 8 (1), conical protrusions 581 and 581 are arranged on the left and right side surfaces at equal intervals on the circumference. In addition, four each are formed. In the example of FIG. 8B, four hemispherical protrusions 582 and 582 are formed on the left and right side surfaces, respectively.

  A cylindrical hole 583 (see FIG. 6B) on the inner peripheral surface of the coupling ring 58 is formed to have a diameter substantially the same as the diameter of the medium diameter shaft portion 65, and the cylindrical hole 583 is moderate in the medium diameter shaft portion 65. It is formed so as to be fitted by fitting.

  As shown in FIG. 7, when the cylindrical shaft portion 63 of the shaft 6 is further pushed into the cylindrical hole 571 of the coupling tube portion 57, the conical protrusions 581 and 581 of the coupling ring 58 (in the case of the example of FIG. 8 (2)) The hemispherical projections 582 and 582) bite into the left end surface 67 of the large-diameter shaft portion 66 and the right end surface 572 of the coupling tube portion 57, and rotational torque is generated between the coupling tube portion 57 of the yoke 51 and the shaft 6. It becomes possible to communicate.

  Further, since the conical protrusion 581 of the coupling ring 58 bites into the right end surface 572 of the coupling cylinder part 57, the thin cylindrical part 573 of the coupling cylinder part 57 is bent radially inward and enters the annular groove 64 of the shaft 6. The shaft 6 is coupled to the coupling cylinder portion 57 of the yoke 51 so as not to move in the axial direction. Therefore, non-circular processing such as serration with high accuracy is not required for the coupling cylinder portion 57 and the shaft 6 of the yoke 51, and the shaft 6 is simply press-fitted in the axial direction into the coupling cylinder portion 57 of the yoke 51. Thus, both transmission of rotational torque and axial fixing are possible at the same time, so that manufacturing costs can be reduced.

  Next, a third embodiment of the present invention will be described. FIG. 9 (1) is a longitudinal sectional view showing a universal joint according to Embodiment 3 of the present invention, and FIG. 9 (2) is a view taken along arrow R in FIG. 9 (1). FIG. 10 (1) is a longitudinal sectional view showing a conventional universal joint, and FIG. 10 (2) is a view taken in the direction of arrow S in FIG. 10 (1). In the following description, only structural portions and operations different from the above embodiment will be described, and redundant description will be omitted. Further, the same parts will be described with the same numbers.

  The third embodiment is an example in which the shape of the slit 56 of the first embodiment is changed to improve the rigidity of the yoke 51. That is, in the first embodiment, the slit 56 is formed over the entire axial length of the coupling cylinder portion 53. On the other hand, the slit 56 of the third embodiment has a rounded-up position 561 from the coupling cylinder portion 53 formed in the middle of the length of the coupling cylinder portion 53 in the axial direction. The left end of the coupling cylinder portion 53 is connected by the connecting wall 562 and is not completely divided by the slit 56.

  Accordingly, as shown in FIG. 10, in the case of the yoke 51 of the first embodiment in which the slit 56 is formed over the entire axial length of the coupling cylinder portion 53, if a large rotational torque acts on the yoke 51, As shown in FIG. 6, the deformation of the slit 56 and the coupling arm portion 52 is increased, and the stress amplitude of the yoke 51 is increased in accordance with the fluctuation of the rotational torque, so that the yoke 51 may be damaged.

  However, in the yoke 51 of the third embodiment, the right end of the coupling arm portion 52 and the left end of the coupling cylinder portion 53 are coupled by the coupling wall 562 and are not completely divided by the slit 56. Therefore, when a large rotational torque is applied to the yoke 51, the deformation of the slit 56 and the coupling arm portion 52 is small, and the stress amplitude of the yoke 51 due to the fluctuation of the rotational torque is small. It is possible to reduce the size of the conventional yoke 51.

  Next, a fourth embodiment of the present invention will be described. FIG. 11 (1) is a side view of a main part showing a fitting state of the female steering shaft 12A and the male steering shaft 12B according to the fourth embodiment of the present invention, and FIG. 11 (2) is a BB view of FIG. It is an expanded sectional view. FIGS. 12 (1) to 12 (3) show a modification of FIG. 11 (2) and correspond to an enlarged cross-sectional view taken along the line BB of FIG. 11 (1).

  FIG. 13 is a graph in which the relationship between the resin coating thickness and the rigidity of the female steering shaft 12A and the male steering shaft 12B of Example 4 of the present invention is obtained by FEM analysis. In the following description, only structural portions and operations different from the above embodiment will be described, and redundant description will be omitted. Further, the same parts will be described with the same numbers.

  The fourth embodiment is an example of the female steering shaft 12A and the male steering shaft 12B that can stably obtain a small sliding resistance and reliably prevent rattling. The structure of the fourth embodiment is not limited to the telescopic shaft composed of the female steering shaft 12A and the male steering shaft 12B, but can rotate the telescopic shaft composed of the male intermediate shaft 15A and the female intermediate shaft 15B. The present invention can be applied to a telescopic shaft composed of an arbitrary male shaft and a female shaft that can transmit torque and are slidably fitted to each other.

  Such a telescopic shaft needs to have a low sliding resistance during expansion and contraction and a small backlash when the steering wheel is operated. For this purpose, either a male shaft or a female shaft is coated with a resin film, and grease or the like is applied as lubricating oil.

  If this resin coating is thin, the variation rate of the sliding resistance increases with respect to the tightening allowance that varies depending on the machining accuracy of the male shaft and the female shaft, and it becomes difficult to stably secure an appropriate sliding resistance. In addition, if the resin coating is thick, the rigidity between the male shaft and the female shaft with respect to the rotational torque is lowered, which increases the feeling of play when the steering wheel is operated, which is not preferable.

  As shown in FIGS. 11 (1) and 11 (2), the steering shaft 12, which is the telescopic shaft of the fourth embodiment of the present invention, can transmit the rotational torque between the female steering shaft 12A and the male steering shaft 12B, and Splines are fitted so that they can move relative to each other in the axial direction.

  As shown in FIG. 11 (2), a female spline 121A is formed on the female steering shaft 12A, and a male spline 121B is formed on the male steering shaft 12B. The resin film 122B is coated. Nylon 11 is used as the material for the resin coating of Example 4 of the present invention. 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.

  In the example of FIG. 12A, a female spline 121A is formed on the female steering shaft 12A, and a male spline 121B is formed on the male steering shaft 12B. A resin film 122A is coated on the periphery.

  As shown in FIG. 12 (2), a rectangular hole 123A is formed on the inner periphery of the female steering shaft 12A, and a rectangular shaft 123B is formed on the outer periphery of the male steering shaft 12B, so that rotational torque can be transmitted to each other. The resin film 125 may be coated on the outer periphery of the square shaft 123B or the inner periphery of the square hole 123A.

  Also, as shown in FIG. 12 (3), a triangular hole 124A is formed on the inner periphery of the female steering shaft 12A, and a triangular shaft 124B is formed on the outer periphery of the male steering shaft 12B so that rotational torque can be transmitted to each other. The resin film 125 may be coated on the outer periphery of the triangular shaft 124B or the inner periphery of the triangular hole 124A.

  As shown in the graph of FIG. 13, when the thickness of the resin film increases, the rigidity between the female steering shaft 12A and the male steering shaft 12B with respect to the rotational torque decreases. If the thickness of the resin coating is 0.2 mm or less, the rigidity is large, but the change in the rigidity is large, and the sliding resistance varies greatly due to a small error in the tightening margin of the female steering shaft 12A and the male steering shaft 12B. .

  Further, when the thickness of the resin coating is 0.8 mm or more, the rate of decrease in rigidity is small, and it may be considered that the rigidity becomes substantially constant. Therefore, in order to easily manage the processing dimensions of the female steering shaft 12A and the male steering shaft 12B and to stably secure an appropriate sliding resistance, the thickness of the resin film is set to 0.2 mm to 0.8 mm. It is appropriate to set the thickness of the resin coating to 0.4 mm to 0.8 mm.

  In the above embodiment, the example in which the present invention is applied to the yoke in which the substantially cylindrical coupling cylinder portion 53 is formed has been described. However, the present invention can be applied to a yoke having a coupling cylinder portion having a substantially U-shaped cross section. Good.

  Further, in the above embodiment, the present invention is a through-bolt method in which bolt holes (blunt holes) 541A and 541B are formed in the flange portions 54A and 54B of the yoke 51, and the flange portions 54A and 54B are clamped by bolts 55 and nuts 551. An example in which is applied has been described. As another example, a nut 551 is not used, a female screw is formed on one of the flange portions 54A and 54B, a male screw 552A of the bolt shaft portion 552 is screwed into the female screw, and a screw bolt method is used to tighten the flange portions 54A and 54B. The present invention may be applied.

It is the whole steering device provided with the universal joint of the example of the present invention. It is a longitudinal cross-sectional view which shows the state which is processing the bolt hole and the seat surface in the universal joint of Example 1 of this invention. It is AA sectional drawing of FIG. FIG. 4 is a view corresponding to FIG. 3 showing a state in which the clamp of the universal joint after the processing of the bolt hole and the seating surface is released. FIG. 4 is a view corresponding to FIG. 3 and showing a state in which a bolt is fastened to the universal joint of Embodiment 1 of the present invention. It is the longitudinal cross-sectional view which shows the joint structure of the universal joint of Example 2 of this invention, and a shaft, and shows the state in the middle of press-fitting a shaft into a universal joint, (2) is P section expanded longitudinal cross-sectional view of (1). is there. FIG. 2 is a longitudinal sectional view showing a coupling structure of a universal joint and a shaft according to a second embodiment of the present invention, and showing a state where the press-fitting of the shaft to the universal joint is completed, and (2) is an enlarged longitudinal sectional view of a Q part in (1). is there. It is a perspective view which shows two examples of the coupling ring used for the coupling structure of the universal joint of Example 2 of this invention, and a shaft. (1) is a longitudinal cross-sectional view which shows the universal joint of Example 3 of this invention, (2) is R arrow directional view of (1). (1) is a longitudinal cross-sectional view which shows the conventional universal joint, (2) is a S arrow view of (1). (1) is the principal part side view which shows the fitting state of 12 A of female steering shafts and male steering shaft 12B of Example 4 of this invention, (2) is BB expanded sectional drawing of (1). (1) to (3) show a modification of FIG. 11 (2), which corresponds to an enlarged cross-sectional view taken along the line BB of FIG. 11 (1). It is the graph which calculated | required the relationship of the thickness and rigidity of the resin film of the female steering shaft 12A of Example 4 of this invention, and the male steering shaft 12B by FEM analysis. (1) is a perspective view which shows the conventional universal joint, (2) is a longitudinal cross-sectional view of (1). It is CC expanded sectional drawing of FIG.14 (2) which shows the state before fastening a volt | bolt to the conventional universal joint. 14 is an enlarged cross-sectional view taken along the line CC in FIG. 14 (2) showing a state in which a bolt is fastened to a conventional universal joint, and (2) is a single bolt when a bolt is fastened to a conventional universal joint. FIG.

Explanation of symbols

11 Steering wheel 12 Steering shaft 12A Female steering shaft 121A Female spline 122A Resin coating 123A Square hole 124A Triangular hole 12B Male steering shaft 121B Female spline 122B Resin coating 123B Square shaft 124B Triangular shaft 125 Resin coating 13 Steering column 13A Outer column 13B Inner column 13B DESCRIPTION OF SYMBOLS 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 53 Coupling cylinder part 531 Female serration 54A, 54B Flange part 541A, 541B Bolt hole 542A, 542B Seat surface 55 Bolt 551 Nut 551A Lower surface 552 Bolt shaft portion 552A Male screw 553 Bolt head 553 Spring washer 56 Slit (cut)
561 Round-up position 562 Connecting wall 57 Connecting cylinder portion 571 Cylindrical hole 572 Right end surface 573 Thin cylindrical portion 574 Outer peripheral surface 58 Connecting ring 581 Conical protrusion 582 Semispherical protrusion 583 Cylindrical hole 6 axis (pinion shaft)
61 Male serration 62 Recessed portion 63 Cylindrical shaft portion 64 Annular groove 65 Medium diameter shaft portion 66 Large diameter shaft portion 67 Left end surface 71 Clamp jig for machining 72 Drill 73 Counterbore bit 74 Counterbore bit

Claims (4)

A coupling cylinder portion having an inner peripheral surface for fitting a shaft to a portion near the base end so as to be able to transmit rotational torque,
A slit formed in the coupling cylinder portion and penetrating the inner peripheral surface,
A pair of flange portions provided integrally with the coupling cylinder portion across the cut,
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,
A shaft having an outer peripheral surface that is inserted into the inner peripheral surface of the coupling cylinder part and is fitted into the inner circumferential surface of the coupling cylinder part so as to transmit rotational torque;
A bolt shaft portion is fitted into concentric bolt holes formed in the pair of flange portions, the interval between the pair of flange portions is narrowed, and the inner peripheral surface of the coupling cylinder 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 state where the bolt is tightened and the outer peripheral surface of the shaft is tightened with the inner peripheral surface of the coupling tube portion, the seat surface of the flange portion that is in contact with the lower surface of the bolt head is formed so that the bolt hole is orthogonal to the bolt surface. A universal joint characterized by The universal joint according to claim 1,
Female serrations are formed on the inner peripheral surface of the coupling cylinder part,
A universal joint, wherein a male serration that engages with the female serration and transmits rotational torque is formed on an outer peripheral surface of the shaft.   A steering apparatus having the universal joint according to any one of claims 1 to 2. A coupling cylinder portion having an inner peripheral surface for fitting a shaft to a portion near the base end so as to be able to transmit rotational torque,
A slit formed in the coupling cylinder portion and penetrating the inner peripheral surface,
A pair of flange portions provided integrally with the coupling cylinder portion across the cut,
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,
A shaft having an outer peripheral surface that is inserted into the inner peripheral surface of the coupling cylinder part and is fitted into the inner circumferential surface of the coupling cylinder part so as to transmit rotational torque;
A bolt shaft portion is fitted into concentric bolt holes formed in the pair of flange portions, the interval between the pair of flange portions is narrowed, and the inner peripheral surface of the coupling cylinder portion is reduced in diameter, In the universal joint provided with a bolt for tightening the outer peripheral surface of the shaft with the inner peripheral surface of the coupling cylinder portion,
The flange portion contacting the lower surface of the bolt head with the deformation corresponding to the state in which the bolt is tightened and the outer peripheral surface of the shaft is tightened with the inner peripheral surface of the coupling cylinder portion is applied to the pair of flange portions. A processing method of a universal joint, wherein the seat surface and the bolt hole are processed into the pair of flange portions.

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