JP6900876B2 - Bonding structure and bonding method between shafts - Google Patents

Description

The present invention relates to an improvement in a coupling structure and a coupling method between shafts, which constitute a torque transmission shaft incorporated in a steering device for an automobile or the like.

FIG. 18 is described in Japanese Patent Application Laid-Open No. 2017-25964 and shows a conventionally known steering device for automobiles. The steering device includes a steering wheel 1, a steering shaft 2, a steering column 3, a pair of universal joints 4a and 4b, an intermediate shaft 5, a steering gear unit 6, and a pair of tie rods 7. ..

The steering wheel 1 is attached to the rear end portion of the steering shaft 2 rotatably supported inside the steering column 3. The front end portion of the steering shaft 2 is connected to the input shaft 8 of the steering gear unit 6 via a pair of universal joints 4a and 4b and an intermediate shaft 5. Then, by converting the rotation of the input shaft 8 into a linear motion of a rack (not shown), the pair of tie rods 7 is pushed and pulled, and the steering wheel is given a steering angle according to the amount of operation of the steering wheel 1. The front-rear direction means the front-rear direction of the vehicle body to which the steering device is assembled.

By the way, in the field of steering devices for automobiles, a torque transmission shaft used for torque transmission may be formed by connecting a plurality of members. In this way, when a plurality of members are connected to form a torque transmission shaft, a pair of shafts arranged adjacent to each other are connected by welding so that torque can be transmitted between the pair of shafts. Is being done.

Japanese Unexamined Patent Publication No. 2017-25964

In recent years, the demand for reliability of a shaft for torque transmission has become more sophisticated. In the case of a torque transmission shaft formed by connecting a plurality of members, the torque transmission function is provided even when a defect such as a crack or peeling occurs in the welded portion connecting the pair of shafts. It is required that it can be secured and that the pair of shafts does not separate from each other. Further, even when a defect occurs in the welded portion, it is required to prevent rattling in the circumferential direction and the radial direction between the pair of shafts.

In view of the above circumstances, the present invention can transmit torque between the shafts without causing rattling even when a defect occurs in the welded portion, and the shafts can communicate with each other. It is an object of the invention to realize a coupling structure and a coupling method between shafts that can prevent separation of the shafts.

The shaft-to-shaft coupling structure of the present invention includes a first shaft, a second shaft, and microprojections.
The first shaft has a first tubular portion provided with an outer peripheral side concave-convex portion and an annular concave groove, respectively, having an uneven shape in the circumferential direction on the outer peripheral surface.
The second shaft has a second tubular portion provided with an inner peripheral side concave-convex portion having a concave-convex shape in the circumferential direction on the inner peripheral surface.
The microprojection can be plastically deformed when the outer peripheral side uneven portion and the inner peripheral side uneven portion are engaged with each other, and the outer surface and the inner peripheral side of the outer peripheral side convex portion constituting the outer peripheral side uneven portion. It is provided on at least one of the inner surfaces of the inner peripheral side recesses constituting the uneven portion.
In the shaft-to-shaft coupling structure of the present invention, the outer peripheral side concavo-convex portion and the inner peripheral side concavo-convex portion are engaged with the outer peripheral surface of the first shaft in a plastically deformed state. The axial end of the second cylinder is welded and fixed.
Further, a plastically deformed portion formed by plastically deforming a portion of the inner peripheral surface of the second tubular portion that coincides with the annular concave groove in the axial direction so as to project inward in the radial direction is formed inside the annular concave groove. It is placed in.

In the present invention, the microprojections can be provided on the outer peripheral side convex portions arranged at every other or every other outer peripheral side convex portion in the circumferential direction among the plurality of outer peripheral side convex portions constituting the outer peripheral side uneven portion.

In the present invention, among the plurality of outer peripheral side convex portions, one microprojection is provided on each outer surface of three or more outer peripheral side convex portions arranged at equal intervals in the circumferential direction of the first tubular portion. Can be provided.
In this case, for example, the microprojection can be provided on the top of the outer peripheral convex portion.

Alternatively, two of the microprojections may be provided on the outer surfaces of at least two outer peripheral convex portions arranged at positions opposite to each other in the radial direction of the first tubular portion among the plurality of outer peripheral side convex portions. it can.
In this case, the microprojections can be provided at two locations on the outer surface of the outer peripheral convex portion, which are separated from the top on both sides in the circumferential direction.

In the present invention, among the plurality of outer peripheral side convex portions, the amount of protrusion to the front side end portion in the insertion direction into the inner peripheral side concave portion is smaller than that in the rear side portion in the insertion direction. A guide portion can be provided.

In the method of connecting the shafts of the present invention, the first tubular portion constituting the first shaft, which is provided with the outer peripheral side concave-convex portion and the annular concave groove, respectively, having an uneven shape in the circumferential direction on the outer peripheral surface is formed on the inner peripheral surface. A part of the outer peripheral surface of the first cylinder portion is the inner circumference of the second cylinder portion inside the second cylinder portion constituting the second shaft provided with the uneven portion on the inner peripheral side having an uneven shape in the circumferential direction. It is inserted until it hits a part of the surface, and is provided on at least one of the outer surface of the outer peripheral side convex portion constituting the outer peripheral side uneven portion and the inner surface of the inner peripheral side concave portion constituting the inner peripheral side uneven portion. In a state where the minute protrusions are plastically deformed, the outer peripheral side uneven portion and the inner peripheral side uneven portion are engaged with the unevenness. Then, by crushing the outer peripheral surface of the second tubular portion inward in the radial direction, the outer peripheral surface of the second tubular portion protrudes inward in the radial direction so as to be arranged inside the annular concave groove. A crimped portion is formed to suppress rattling of the first shaft and the second shaft in the axial direction. After that, the first shaft and the second shaft are welded and fixed.

According to the present invention, even when a defect occurs in the welded portion, torque can be transmitted between the shafts without causing rattling, and separation between the shafts can be prevented.

FIG. 1 is a schematic view showing an example of a steering device to which the shaft-to-shaft coupling structure according to the first example of the embodiment is applied. FIG. 2 is a cross-sectional view showing an intermediate shaft taken out from the steering device shown in FIG. 1 with respect to the first example of the embodiment. FIG. 3 is a cross-sectional view showing the first example of the embodiment in which the intermediate shaft shown in FIG. 2 is separated at the position of the joint member and the first telescopic shaft and the female joint are taken out. FIG. 4 is a cross-sectional view showing the first example of the embodiment in which the intermediate shaft shown in FIG. 2 is separated at the position of the joint member and the second telescopic shaft and the male joint are taken out. FIG. 5 is an enlarged view of part A of FIG. 4 showing a first example of the embodiment. FIG. 6 is a partial perspective view of a portion corresponding to the portion B of FIG. 4, showing the first example of the embodiment. FIG. 7 is a partial perspective perspective view of a portion corresponding to the portion B of FIG. 4, showing the first example of the embodiment. FIG. 8 is an end sectional view showing a female shaft corresponding to the second shaft taken out with respect to the first example of the embodiment. FIG. 9 is a plan view showing a male joint corresponding to the first shaft taken out with respect to the first example of the embodiment. FIG. 10 is a perspective view showing a male joint corresponding to the first shaft taken out with respect to the first example of the embodiment. FIG. 11 is a partially enlarged view (B) of end views (A) and (A) showing the male joint corresponding to the first shaft taken out with respect to the first example of the embodiment. FIG. 12 is a diagram corresponding to FIG. 11 showing a second example of the embodiment. FIG. 13 is a diagram corresponding to FIG. 11A showing a third example of the embodiment. FIG. 14 is a diagram corresponding to FIG. 11A showing a fourth example of the embodiment. FIG. 15 is a partially enlarged view of an end face showing a female shaft corresponding to the second shaft taken out with respect to the fifth example of the embodiment. 16A and 16B are views showing a male joint corresponding to the first shaft taken out with respect to the sixth example of the embodiment, FIG. 16A is a plan view, FIG. 16B is an end view, and FIG. 16C is an end view. Is a perspective view. FIG. 17 is a diagram corresponding to FIG. 16 showing a seventh example of the embodiment. FIG. 18 is a partial cross-sectional side view showing a conventionally known steering device.

[First Example of Embodiment]
A first example of the embodiment will be described with reference to FIGS. 1 to 11. In this example, the structure of the intermediate shaft 5a is devised among the plurality of torque transmission shafts constituting the steering device. Specifically, the coupling structure of the male joint 46 and the female shaft 30, which are a pair of shafts constituting the intermediate shaft 5a, is devised. Hereinafter, the overall structure of the steering device and the intermediate shaft 5a will be described, and the characteristic parts of this example will be described.

[Overview of steering device]
The steering device for automobiles includes a steering wheel 1, a steering shaft 2, a steering column 3, a pair of universal joints 4c and 4d, an intermediate shaft 5a, a steering gear unit 6, and a pair of tie rods 7. I have.

The steering shaft 2 is rotatably supported inside the steering column 3 supported by the vehicle body. A driver-operated steering wheel 1 is attached to the rear end of the steering shaft 2, and the front end of the steering shaft 2 is a steering gear via a pair of universal joints 4c and 4d and an intermediate shaft 5a. It is connected to the input shaft 8 of the unit 6. Therefore, when the driver rotates the steering wheel 1, the rotation of the steering wheel 1 is transmitted to the input shaft 8 of the steering gear unit 6. The rotation of the input shaft 8 is converted into a linear motion of the rack meshed with the input shaft 8 and pushes and pulls the pair of tie rods 7. As a result, the steering wheel is provided with a steering angle corresponding to the amount of operation of the steering wheel 1.

[Composition of intermediate shaft]
The intermediate shaft 5a is a torque transmission shaft that transmits torque, and as shown in FIG. 2, the first telescopic shaft 9 and the second telescopic shaft 10, each of which can expand and contract in the axial direction, are torqued by the joint member 11. It is configured by connecting so that it can be transmitted.

The first telescopic shaft 9 is configured so that the entire length can be contracted only when an impact load having a magnitude equal to or larger than a predetermined value is applied in the axial direction, whereas the second telescopic shaft 10 causes a collision accident. It is configured so that the entire length can be expanded and contracted in a steady state where it is not. Therefore, in the steady state, only the second telescopic shaft 10 expands and contracts to change the overall length of the intermediate shaft 5a, but when a collision accident occurs, each of the first telescopic shaft 9 and the second telescopic shaft 10 expands and contracts. By contracting, the total length is shortened. The intermediate shaft 5a of this example is used for a large vehicle, and has a longer axial dimension than that used for a general ordinary passenger car.

[Structure of the first telescopic shaft]
As shown in FIGS. 2 and 3, the first telescopic shaft 9 includes an inner shaft 12 and an outer tube 13. The inner shaft 12 and the outer tube 13 are coupled so that torque can be transmitted and relative displacement in the axial direction is possible only at the time of a temporary collision. In other words, the inner shaft 12 and the outer tube 13 are coupled so that relative displacement in the axial direction becomes impossible in a steady state.

The inner shaft 12 is made of metal and has a yoke portion 14 on one side in the axial direction and a shaft portion 15 on the other side in the axial direction. In this example, the yoke portion 14 and the shaft portion 15 are integrally provided. That is, the yoke portion 14 and the shaft portion 15 are not connected by fitting or welding, but are integrally formed by plastically deforming the material by forging or the like.

The yoke portion 14 constitutes a universal joint 4d by another yoke 16 connected to the input shaft 8 of the steering gear unit 6 and a cross shaft (not shown), and includes a base portion 17 and a pair of arm portions 18. Have. The central portion of the other side surface of the base portion 17 in the axial direction is continuous with the end surface of one side portion in the axial direction of the shaft portion 15. The radial outer portion of the other side surface in the axial direction of the base portion 17 is a circular ring surface 19 existing on a virtual plane orthogonal to the central axis of the shaft portion 15.

The pair of arm portions 18 are formed in a substantially flat plate shape, and extend from two positions on the opposite side of the base portion 17 in the diametrical direction to one side in the axial direction. Further, the tip portion of the arm portion 18 is provided with a circular hole 20 for rotatably supporting the shaft portion constituting the cross axis, coaxially with each other.

The shaft portion 15 has a substantially columnar shape, and is formed in a solid state over almost the entire length. On the other side of the shaft portion 15 in the axial direction, a hollow portion 21 opened only at the end surface on the other side of the shaft portion 15 in the axial direction is provided. A male serration 22 is provided on the outer peripheral surface of the other half of the shaft portion 15 in the axial direction. On the other hand, a concave curved surface 23 having a concave arc shape is provided on the outer peripheral surface of the end portion of the shaft portion 15 on one side in the axial direction. The concave curved surface 23 is a so-called corner R portion, has a single radius of curvature r, and is smoothly continuous with the annular surface 19 which is the other side surface in the axial direction of the base portion 17 constituting the yoke portion 14. ing.

The outer tube 13 is made of metal and has a hollow circular tubular shape. A pair of coupling cylinder portions 24a and 24b are provided on both sides of the outer tube 13 in the axial direction, and a bellows-shaped bellows portion 25 is provided in the intermediate portion in the axial direction of the outer tube 13.

Of the pair of coupling cylinders 24a and 24b, the first female serration 26 is provided on the inner peripheral surface of the coupling cylinder 24a on one side in the axial direction, and the inside of the coupling cylinder 24b on the other side in the axial direction. A second female serration 27 is provided on the peripheral surface.

The bellows portion 25 is a portion that absorbs the impact load due to the collision by plastically deforming so as to bend at the time of an offset collision, and the driver operates the steering wheel 1 in a steady state before the collision accident occurs. It has a torsional strength that does not deform depending on the load in the torsional direction that is applied based on the above. The bellows portion 25 is configured by arranging a plurality of mountain portions having a large diameter portion and valley portions having a small diameter portion alternately in the axial direction. Further, in this example, the top of the mountain portion and the bottom of the valley portion have an arc shape in cross section.

In this example, in order to connect the inner shaft 12 and the outer tube 13 so that torque can be transmitted and the relative displacement in the axial direction at the time of a temporary collision is possible, the male serration 22 of the inner shaft 12 and the outer tube 13 are connected. The first female serration 26 is engaged with the serration, and the fitting portion between the inner shaft 12 and the outer tube 13 is a so-called elliptical fitting. That is, plastic deformation having an elliptical cross-sectional shape at the end of the shaft portion 15 constituting the inner shaft 12 on the other side in the axial direction and the end of the coupling cylinder portion 24a constituting the outer tube 13 on the other side in the axial direction. Parts 28a and 28b are formed, respectively. In FIG. 3, wavy lines are provided in the formation ranges of the plastic deformation portions 28a and 28b, respectively.

In this example, with the above-described configuration, torque can be transmitted between the other side portion of the shaft portion 15 constituting the inner shaft 12 in the axial direction and the coupling cylinder portion 24a constituting the outer tube 13 in the axial direction. It is coupled so that relative displacement in the axial direction is possible only in the case of a primary collision where a large impact load is applied to. Further, since the plastic deformed portions 28a and 28b serve as resistance when the inner shaft 12 and the outer tube 13 are displaced relative to each other in the axial direction, the inner shaft 12 and the outer tube 13 are displaced relative to each other in the axial direction, and the first When the telescopic shaft 9 contracts, it absorbs energy due to collision.

The plastic deformed portions 28a and 28b as described above are formed, for example, as follows.
First, the axially opposite side of the shaft portion 15 is slightly inserted into the axially one side of the outer tube 13. That is, the one side portion in the axial direction of the coupling cylinder portion 24a and the other side portion in the axial direction of the shaft portion 15 are engaged with each other. Next, one side of the coupling cylinder 24a in the axial direction is crushed from the outside in the radial direction with a tool, and the inner peripheral surface of the one side of the coupling cylinder 24a in the axial direction and the outer peripheral surface of the other side of the shaft 15 in the axial direction are crushed. , Plastically deformed into an elliptical cross section to form plastically deformed portions 28a and 28b in the portion. After that, the inner shaft 12 and the outer tube 13 are displaced relative to each other in the axial direction so as to reduce the total length of the first telescopic shaft 9, and the total length of the first telescopic shaft 9 is set to a predetermined axial length in a steady state. .. As a result, the plastically deformed portion 28a of the inner shaft 12 and the plastically deformed portion 28b of the outer tube 13 are arranged apart from each other in the axial direction.

[Structure of the second telescopic shaft]
As shown in FIGS. 2 and 4, the second telescopic shaft 10 includes a male shaft 29, a female shaft 30, a plurality of balls 31, a plurality of rollers 32, and a plurality of leaf springs 33. ing.

The male shaft 29 is configured to be solid over the entire length, and has a first male-side axial groove 34 and a second male-side axial groove 35, each of which extends in the axial direction, on the outer peripheral surface of one side in the axial direction. Alternately in the circumferential direction. The first male side axial groove 34 has a substantially isosceles trapezoidal cross-sectional shape, and the circumferential width of the opening is wider than the circumferential width of the bottom. On the other hand, the second male side axial groove 35 has a concave arc shape in cross section. Further, a ring-shaped stopper 36 is fixed to the outer peripheral surface of the end portion of the male shaft 29 on one side in the axial direction. As a result, the ball 31 arranged in the first male side axial groove 34 and the roller 32 arranged in the second male side axial groove 35 are moved to the first male side axial groove 34 and the second male side. It is prevented from coming out from the axial groove 35 to one side in the axial direction. A yoke 37 separate from the male shaft 29 is fixed to the other end of the male shaft 29 in the axial direction by welding. The yoke 37 constitutes a universal joint 4c together with another yoke 38 and a cross shaft connected to the front end portion of the steering shaft 2.

The female shaft 30 corresponds to the second shaft, and is formed in a hollow circular tubular shape as a whole, and has an axial groove 39 on the first female side and a second female side, each of which extends in the axial direction, on the inner peripheral surface. Axial grooves 40 are alternately provided in the circumferential direction. The first female side axial groove 39 and the second female side axial groove 40 each have a concave arc shape in cross section.

On one side of the female shaft 30 in the axial direction, a fixed cylinder portion 44 corresponding to a second cylinder portion into which a part of the joint member 11 is inserted is provided inside the female shaft 30. Of the inner peripheral surface of the fixed tubular portion 44, the portion adjacent to one side in the axial direction of the first female side axial groove 39 and the second female side axial groove 40 is the inner peripheral side having an uneven shape with respect to the circumferential direction. It has an uneven portion 41. The inner peripheral side concave-convex portion 41 forms a plurality of inner peripheral side concave portions 42 each having a concave arc shape with a long cross section in the axial direction on the cylindrical inner peripheral surface of the female shaft 30 at equal intervals in the circumferential direction. It is composed of. The other axial portion of the inner peripheral side recess 42 is continuous with the axial one side portion of the first female side axial groove 39 or the second female side axial groove 40. Further, of the inner peripheral surfaces of the female shaft 30 on one side in the axial direction, the inner peripheral surface of the concave-convex portion 41 on the inner peripheral side has a tapered abutment surface whose inner diameter increases toward one side in the axial direction. Has 43. Inner peripheral side recesses 42 are opened at a plurality of equidistant positions of the abutting surface 43 in the circumferential direction. Further, on the inner peripheral surface of the end portion on one side of the female shaft 30 in the axial direction, the inner diameter is constant over the axial direction, and the other side portion in the axial direction is continuous with the large diameter side portion of the abutting surface 43. It has a large diameter portion 64 of.

When the male shaft 29 is inserted inside the female shaft 30, the first male side axial groove 34 and the first female side axial groove 39 are aligned in the circumferential direction, and the second male side The phases of the axial groove 35 and the second female axial groove 40 in the circumferential direction are matched. Then, a plurality of balls 31 are arranged between the first male side axial groove 34 and the first female side axial groove 39. Further, a leaf spring 33 is arranged between the first male side axial groove 34 and the plurality of balls 31, and preload is applied to the plurality of balls 31. Further, one roller 32 is arranged between the second male side axial groove 35 and the second female side axial groove 40.

In the second telescopic shaft 10 as described above, the male shaft 29 and the female shaft 30 are combined so that torque can be transmitted and the entire length can be expanded and contracted in a steady state. In particular, the second telescopic shaft 10 increases when a plurality of balls 31 and leaf springs 33 transmit torque between the male shaft 29 and the female shaft 30 during low torque transmission, and the transmitted torque increases. A plurality of rollers 32 transmit the torque of the minute. Further, when the male shaft 29 and the female shaft 30 are displaced relative to each other in the axial direction, the plurality of balls 31 roll between the first male side axial groove 34 and the first female side axial groove 39. The plurality of rollers 32 slide and slide between the second male side axial groove 35 and the second female side axial groove 40. Further, in this example, since the plurality of balls 31 are pressed against the inner surface of the first female axial groove 39 by the elasticity of the leaf spring 33, the male shaft 29 and the female shaft 30 are prevented from rattling. To.

[Structure of joint members]
In this example, the first telescopic shaft 9 and the second telescopic shaft 10 as described above are connected by a joint member 11 so as to be able to transmit torque. The joint member 11 has a female joint 45 and a male joint 46. The female joint 45 is fixed to the coupling cylinder portion 24b of the outer tube 13 that constitutes the first telescopic shaft 9, and the male joint 46 is fixed to the female shaft 30 that constitutes the second telescopic shaft 10.

The female joint 45 is formed in a substantially cylindrical shape as a whole. A male serration 47 is provided on the outer peripheral surface of one side of the female joint 45 in the axial direction, and a female serration 48 is provided on the inner peripheral surface of the other side of the female joint 45 in the axial direction. Further, a slit 49 extending in the axial direction is provided in the other half of the female joint 45 in the axial direction, and a pair of slits 49 extending outward in the radial direction are provided on both sides of the slit 49 in the circumferential direction. A collar portion 50 is provided. Further, the pair of collar portions 50 are provided with screw holes 51 coaxially with each other.

Then, the male serration 47 provided on the outer peripheral surface on one side in the axial direction of the female joint 45 is serrated engaged with the second female serration 27 provided on the inner peripheral surface of the coupling cylinder portion 24b of the outer tube 13. There is. Further, the outer peripheral surface of the female joint 45 and the end surface of the coupling cylinder portion 24b on the other side in the axial direction are welded and fixed by the welding bead portion 52 over the entire circumference. As a result, the female joint 45 and the outer tube 13 are coupled so that torque can be transmitted.

The male joint 46 corresponds to the first shaft, and has a joint shaft portion 53 on one side in the axial direction and a joint cylinder portion 54 corresponding to the first cylinder portion on the other side in the axial direction. A male serration 55 is provided on the outer peripheral surface of the joint shaft portion 53 over the entire circumference, and a notch 56 is provided in a part in the circumferential direction in a direction perpendicular to the central axis of the joint shaft portion 53. There is.

The joint tubular portion 54 is formed in a substantially cylindrical shape as a whole. An annular groove 57 recessed inward in the radial direction is provided in the middle portion in the axial direction of the joint cylinder portion 54 over the entire circumference. Further, the outer peripheral surface of the end portion of the joint cylinder portion 54 on the other side in the axial direction has an outer peripheral side uneven portion 58 having a concave-convex shape in the circumferential direction. The outer peripheral side concavo-convex portion 58 has a plurality of (six in the illustrated example) outer peripheral side convex portions 59 each having a long semi-cylindrical cross section in the axial direction, and a cylindrical surface at the other end of the joint tubular portion 54 in the axial direction. It is formed by forming the outer peripheral surface of the shape at equal intervals in the circumferential direction. In this example, the outer peripheral side convex portion 59 has a size and a shape that can be loosely inserted into the inner peripheral side concave portion 42 instead of being strongly press-fitted. Therefore, in this example, the dimensional and shape accuracy of the outer peripheral side convex portion 59 and the inner peripheral side concave portion 42 need not be high accuracy. Further, among the outer peripheral surfaces of the joint tubular portion 54, between the ends of the outer peripheral side convex portions 59 adjacent to each other in the circumferential direction on one side in the axial direction, the more toward one side in the axial direction, the more outward in the radial direction. It has an inclined surface 60 inclined in the direction.

In this example, out of a total of six outer peripheral side convex portions 59 constituting the outer peripheral side convex portion 58, three outer peripheral side convex portions 59 arranged at equal intervals in the circumferential direction are formed on the outer surface of the outer peripheral side convex portions 59. Two microprojections 61 are provided. Specifically, with respect to each of the three outer peripheral side convex portions 59, microprojections 61 are provided at positions separated by the same length on both sides in the circumferential direction from the top having the largest amount of protrusion in the radial direction. ing.

The micro-projection 61 projects in the normal direction with respect to the portion of the outer surface of the outer peripheral side convex portion 59 on which the micro-projection 61 is formed, and the amount of protrusion P1 from the outer surface of the outer peripheral side convex portion 59 is 0. It is about 1 mm, which is sufficiently smaller (for example, about 1/20) than the protrusion amount P2 of the outer peripheral side convex portion 59 itself. Further, the micro-projection 61 is configured to be sufficiently thin so that it can be plastically deformed when the outer peripheral side uneven portion 58 and the inner peripheral side uneven portion 41 are engaged with the uneven portion. In this example, such a minute protrusion 61 is formed by forging or cutting the outer surface of the outer peripheral convex portion 59, for example.

In the illustrated example, the microprojection 61 is configured to have a semicircular cross section, and is provided over the entire length of the outer peripheral side convex portion 59. However, the cross-sectional shape is not limited to a semicircular shape, and various shapes such as a rectangular shape and a triangular shape can be adopted, and the formation range thereof is also provided only in a part of the outer peripheral side convex portion 59 in the axial direction. You can also. Further, in the illustrated example, the protrusion amount P1 from the outer surface of the outer peripheral side convex portion 59 of the microprojection 61 is constant over the entire length, but the protrusion amount increases from the tip end side to the proximal end side of the outer peripheral side convex portion 59. A larger configuration may be adopted. If such a configuration is adopted, the gap between the outer peripheral side convex portion 59 and the inner peripheral side concave portion 42 is formed by the outer peripheral side convex portion 59 due to the insertion work of the outer peripheral side convex portion 59 into the inner peripheral side concave portion 42. Since the size can be gradually reduced toward the base end side of the insertion work, the workability of the insertion work can be improved.

Then, in this example, the joint cylinder portion 54 of the male joint 46 is hit by the inclined surface 60 provided on the outer peripheral surface of the joint cylinder portion 54 against the abutting surface 43 provided on the inner peripheral surface of the female shaft 30. It is inserted inside the fixed cylinder portion 44 of the female shaft 30 until it comes into contact with the female shaft 30. As a result, the male joint 46 is positioned with respect to the female shaft 30 in the axial direction, and the plurality of outer peripheral side convex portions 59 constituting the outer peripheral side uneven portion 58 of the male joint 46 are formed on the inner peripheral side uneven portion 41 of the female shaft 30. Is inserted into each of the plurality of inner peripheral side concave portions 42 constituting the above, and the inner peripheral side uneven portion 41 and the outer peripheral side uneven portion 58 are engaged with each other. In this example, in particular, the microprojection 61 provided on the outer surface of the outer peripheral side convex portion 59 is plastically deformed so as to be crushed by the inner surface of the inner peripheral side concave portion 42, and the outer surface and the inner peripheral side concave portion 42 of the outer peripheral side convex portion 59 are formed. The uneven portion 41 on the inner peripheral side and the uneven portion 58 on the outer peripheral side are engaged with each other while filling the gap between the inner surface and the inner surface.

Further, the large diameter portion 64, which is the inner peripheral surface of one side of the female shaft 30 in the axial direction, is press-fitted into the outer peripheral surface of the joint cylinder portion 54, and of the large diameter portions 64, the male joint 46 is annular in the axial direction. A plurality of caulking portions 62 formed in a portion consistent with the concave groove 57 are arranged inside the annular concave groove 57. The caulking portions 62 are provided at equal intervals with respect to the circumferential direction of the female shaft 30. In this example, the tip of the tool crushes a plurality of circumferential directions of the outer peripheral surface of the fixed cylinder 44 inward in the radial direction to form recesses 63 on the outer peripheral surface of the female shaft 30, respectively. A caulking portion 62 is formed by plastically deforming a plurality of portions of the diameter portion 64 that match the annular groove 57 in the axial direction so as to project inward in the radial direction. As a result, rattling in the axial direction between the male joint 46 and the female shaft 30 is suppressed in the state before the joint cylinder portion 54 and the female shaft 30 are welded and fixed.

Further, a portion of the outer peripheral surface of the joint cylinder portion 54 exposed from the female shaft 30 and an end surface on one side of the female shaft 30 in the axial direction are welded and fixed by a weld bead portion 66 over the entire circumference. In this example, the joint cylinder portion 54 is inserted inside the fixed cylinder portion 44, and the crimped portions 62 are formed at a plurality of locations in the circumferential direction of the inner peripheral surface of the fixed cylinder portion 44, and then the shaft is formed from the crimped portion 62. A weld bead portion 66 is formed between the outer peripheral surface of the joint cylinder portion 54 and the end surface on one side of the female shaft 30 in the axial direction, which are separated in the direction. This prevents the influence of welding heat when forming the welding bead portion 66 from being transmitted to the caulking portion 62. Further, such a welding operation can be performed in a state where rattling in the axial direction between the male joint 46 and the female shaft 30 is suppressed.

Further, the joint shaft portion 53 of the male joint 46 is inserted inside the other side portion in the axial direction of the female joint 45, and the male serration 55 and the female serration 48 are serrated engaged with each other. As a result, the female joint 45 and the male joint 46 are coupled so that torque can be transmitted. Further, a bolt (not shown) is screwed into a screw hole 51 of a pair of flange portions 50 constituting the female joint 45. Then, the intermediate portion of the bolt is arranged inside the notch 56 to prevent the joint shaft portion 53 from coming out from the female joint 45 to the other side in the axial direction.

In the steady state, the intermediate shaft 5a of this example as described above expands and contracts due to the relative displacement of the male shaft 29 and the female shaft 30 constituting the second telescopic shaft 10 in the axial direction. This prevents the vibration input from the tire during traveling from being transmitted to the steering wheel 1.

When a so-called full-wrap collision occurs in which the entire front surface of the vehicle body collides with another automobile or the like, the first telescopic shaft 9 and the second telescopic shaft 10 contract respectively. As a result, the overall length of the intermediate shaft 5a is shortened while absorbing the impact load. This prevents the steering wheel 1 from being pushed up toward the driver.

On the other hand, when a part of the front surface of the vehicle body is biased in the width direction and collides with another automobile or the like, a so-called offset collision occurs, the engine room is deformed and the intermediate shaft 5a is moved in the axial direction. It may not be able to shrink. In this case, the outer tube 13 bends at the bellows portion 25 based on the impact load associated with the collision. As a result, the impact load is absorbed, and the bent intermediate shaft 5a is housed in the gap existing between the peripheral parts to prevent the intermediate shaft 5a from being displaced rearward. Therefore, even in the case of an offset collision, it is possible to prevent the steering wheel 1 from being pushed up toward the driver. Whether or not the total length of the intermediate shaft 5a contracts when an offset collision occurs depends on how an impact load is applied, how the engine room is deformed, and the like.

In this example having the above configuration, the male joint 46 and the female shaft are related to the joint portion between the male joint 46 and the female shaft 30, which are a pair of shafts constituting the intermediate shaft 5a which is a torque transmission shaft. Even if the weld bead portion 66 connecting the 30 is defective, torque can be transmitted between the male joint 46 and the female shaft 30 without causing rattling (play). , It is possible to prevent the male joint 46 and the female shaft 30 from being separated.
That is, in this example, the microprojections 61 provided on the outer surface of the outer peripheral side convex portion 59 are plastically deformed by the inner surface of the inner peripheral side concave portion 42, and the outer surface of the outer peripheral side convex portion 59 and the inner surface of the inner peripheral side concave portion 42 are formed. In a state where the gap between the two is filled, the inner peripheral side uneven portion 41 and the outer peripheral side uneven portion 58 are concavely engaged with each other. Therefore, even if a defect occurs in the weld bead portion 66, torque can be transmitted between the male joint 46 and the female shaft 30 without causing rattling in the circumferential direction or the radial direction. .. Moreover, in this example, in order to prevent rattling between the male joint 46 and the female shaft 30, the configuration in which the outer peripheral side convex portion 59 is strongly press-fitted into the inner peripheral side concave portion 42 is not adopted. That is, in this example, the outer peripheral side convex portion 59 can be loosely inserted into the inner peripheral side concave portion 42 in a state where the micro protrusion 61 is not provided. Therefore, it is not necessary to increase the dimensional and shape accuracy of the inner peripheral side concave portion 42 and the outer peripheral side convex portion 59, and a high degree of accuracy control is not required. Can be achieved. Further, in this example, since the microprojections 61 are provided on the outer surfaces of the three outer peripheral convex portions 59 arranged at equal intervals in the circumferential direction, the central axis of the male joint 46 and the central axis of the female axis 30 are provided. Is easy to match. Further, since the micro-projection 61 is provided, it is possible to perform backlash in the circumferential direction between the male joint 46 and the female shaft 30 when performing the caulking work and the press-fitting work.

Further, in this example, since the caulking portion 62 formed on the inner peripheral surface of the female shaft 30 is arranged inside the annular concave groove 57 formed in the male joint 46, a defect occurs in the weld bead portion 66. In this case as well, it is possible to prevent the male joint 46 from coming out of the female shaft 30 in the axial direction.

Further, in this example, in the state where the intermediate shaft 5a is assembled, by visually confirming that the recessed portion 63 is formed on the outer peripheral surface of the female shaft 30, the caulking portion 62 is formed on the inner peripheral surface of the female shaft 30. Can be confirmed to be formed. Therefore, it is possible to easily confirm whether or not the caulking portion 62 is formed.

[Second Example of Embodiment]
A second example of the embodiment will be described with reference to FIG. In this example, out of a total of six outer peripheral side convex portions 59 constituting the outer peripheral side convex portion 58a, three outer peripheral side convex portions 59 arranged at equal intervals in the circumferential direction are formed on the outer surface of the outer peripheral side convex portions 59. The microprojections 61 are provided one by one. Specifically, among the outer surfaces of the three outer peripheral side convex portions 59, the microprojections 61 are provided on the apex having the largest amount of protrusion in the radial direction.

In this example, a total of three microprojections 61 arranged at equal intervals in the circumferential direction are plastically deformed when the inner peripheral side uneven portion 41 (see FIG. 8) and the outer peripheral side uneven portion 58a are engaged with the unevenness. The gap between the outer surface of the outer peripheral side convex portion 59 and the inner surface of the inner peripheral side concave portion 42 (see FIG. 8) is filled. Further, in this example, since the number of microprojections 61 formed is smaller than that in the first example of the embodiment, the man-hours for processing the microprojections 61 can be reduced. Further, since the microprojection 61 is provided on the top of the outer peripheral convex portion 59, it is possible to effectively prevent rattling of the male joint 46 and the female shaft 30 (see FIG. 8) in the radial direction. Other configurations and effects are the same as in the first example of the embodiment.

[Third example of the embodiment]
A third example of the embodiment will be described with reference to FIG. In this example, of the total of six outer peripheral side convex portions 59 constituting the outer peripheral side convex portion 58b, the outer surfaces of the two outer peripheral side convex portions 59 arranged at opposite positions with respect to the diameter direction of the joint cylinder portion 54 are formed on the outer surface. Two microprojections 61 are provided. Specifically, with respect to each of the two outer peripheral side convex portions 59, microprojections 61 are provided at two locations deviated from the top on both sides in the circumferential direction by the same length.

In this example, since the number of microprojections 61 formed is smaller than that of the first example of the embodiment, the man-hours for processing the microprojections 61 can be reduced. Other configurations and effects are the same as in the first example of the embodiment.

[Fourth Example of Embodiment]
A fourth example of the embodiment will be described with reference to FIG. In this example, out of a total of six outer peripheral side convex portions 59 constituting the outer peripheral side convex portion 58c, the outer surfaces of the two outer peripheral side convex portions 59 arranged at positions opposite to each other in the radial direction of the joint cylinder portion 54. , The microprojections 61 are provided one by one. Specifically, microprojections 61 are provided on the tops of the two outer peripheral convex portions 59.

In this example, since the number of microprojections 61 formed is smaller than that of the first example of the embodiment, the man-hours for processing the microprojections 61 can be reduced. Other configurations and effects are the same as those of the first, second and third examples of the embodiment.

[Fifth Example of Embodiment]
A fifth example of the embodiment will be described with reference to FIG. In this example, out of a total of six inner peripheral side recesses 42 constituting the inner peripheral side uneven portion 41a, the inner surfaces of the three inner peripheral side recesses 42 arranged at equal intervals every other in the circumferential direction. , Two microprojections 61a are provided. Specifically, with respect to each of the three inner peripheral side recesses 42, the minute protrusions 61a are provided at positions separated by the same length on both sides in the circumferential direction from the bottom where the amount of recess in the radial direction is the largest. It is provided.

In this example, a total of six microprojections 61a formed on the inner surface of the inner peripheral side concave portion 42 are plastic when the inner peripheral side uneven portion 41a and the outer peripheral side uneven portion 58 (see FIG. 10) are engaged with each other. It is deformed to fill the gap between the outer surface of the outer peripheral side convex portion 59 and the inner surface of the inner peripheral side concave portion 42. It should be noted that the outer surface of the outer peripheral side convex portion 59 constituting the outer peripheral side convex portion 58 may or may not be provided with minute protrusions. When the microprojections are provided on the outer surface of the outer peripheral side convex portion 59, it is preferable to provide the microprojections on the outer surface of the outer peripheral side convex portion 59 inserted inside the inner peripheral side concave portion 42 in which the microprojections are not provided. .. Other configurations and effects are the same as in the first example of the embodiment.

[6th Example of Embodiment]
A sixth example of the embodiment will be described with reference to FIG. In this example, all the outer peripheral side convex portions 59a constituting the outer peripheral side concave-convex portion 58d have a stepped shape, and the semi-cylindrical convex portion main body 67 on the base end side and the semi-cylindrical guide portion 68 on the tip end side are formed. It is composed of and. The guide portion 68 has a smaller amount of protrusion outward in the radial direction and a width dimension in the circumferential direction than the convex portion main body 67. Further, in this example, among the outer peripheral side convex portions 59a, the microprojections 61 are provided only on the outer surface of the convex portion main body 67, and the microprojections are not provided on the outer surface of the guide portion 68.

In this example having the above configuration, the guide portion 68 exerts a guiding function when the outer peripheral side uneven portion 58d is inserted into the inner peripheral side uneven portion 41 (see FIG. 8), so that the outer peripheral side uneven portion is exhibited. The portion 58d can be easily inserted into the inner peripheral side uneven portion 41. In particular, in this example, since the minute protrusion 61 is provided on the outer surface of the outer peripheral side convex portion 59a, when the guide portion 68 is not provided, the tip portion of the outer peripheral side convex portion 59a is set to the inner peripheral side concave portion 42 (see FIG. 8). ), It is necessary to plastically deform the microprojection 61 from the moment it starts to be inserted. However, in this example, since the guide portion 68 can be loosely inserted inside the inner peripheral side concave portion 42, the outer peripheral side convex portion 59a is formed on the inner circumference. The microprojection 61 can be plastically deformed after being inserted into the side recess 42 to some extent. Therefore, the workability of the engagement work between the outer peripheral side uneven portion 58d and the inner peripheral side uneven portion 41 can be improved. Other configurations and effects are the same as in the first example of the embodiment.

[7th example of the embodiment]
A seventh example of the embodiment will be described with reference to FIG. In this example, all the outer peripheral side convex portions 59b constituting the outer peripheral side uneven portion 58e are composed of a semi-cylindrical convex portion main body 67 on the base end side and a 1/4 spherical guide portion 68a on the tip end side. ing. Even in this example, the guide portion 68a has a smaller amount of protrusion outward in the radial direction and a width dimension in the circumferential direction than the convex portion main body 67.

In this example having the above configuration, the outer surface of the guide portion 68a is a spherical convex surface, and the protrusion amount in the radial direction and the width dimension in the circumferential direction of the guide portion 68a are the base ends of the outer peripheral side convex portion 59b. Since the size increases toward the side, the workability of the work of inserting the tip of the outer peripheral side convex portion 59b into the inner peripheral side concave portion 42 (see FIG. 8) can be further improved. Other configurations and effects are the same as those of the first and sixth examples of the embodiment.

The shape of the guide portion provided at the tip of the convex portion on the outer peripheral side is not limited to a semicircular columnar shape or a 1/4 spherical shape, and various shapes such as a semicircular cone shape, a triangular cone shape, and a square cone shape shall be adopted. Can be done. Further, a male serration can be provided on the shaft portion of the inner shaft constituting the first telescopic shaft over the entire length thereof. If such a configuration is adopted, torque can be transmitted between the inner shaft and the outer tube even when the total length of the first telescopic shaft is shortened. Further, as a method of forming the plastically deformed portion on the inner peripheral surface of the second cylinder portion, embossing or the like can be used in addition to the caulking as described in each example of the embodiment. Further, the present invention can be implemented by appropriately combining the structures of the examples of the embodiments as appropriate.

1 Steering wheel 2 Steering shaft 3 Steering column 4a, 4b, 4c, 4d Flexible joint 5, 5a Intermediate shaft 6 Steering gear unit 7 Tie rod 8 Input shaft 9 First telescopic shaft 10 Second telescopic shaft 11 Joint member 12 Inner shaft 13, 13a Outer tube 14 York part 15 Shaft part 16 York 17 Base part 18 Arm part 19 Circular ring surface 20 Circular hole 21 Hollow part 22 Male serration 23 Concave curved surface 24a, 24b Coupling cylinder part 25 Bellows part 26 First female serration 27 Second female Serration 28a, 28b Plastic deformation part 29 Male shaft 30 Female shaft 31 Ball 32 Roller 33 Leaf spring 34 First male side axial groove 35 Second male side axial groove 36 Stopper 37 York 38 York 39 First female side axial groove 40 Second female side axial groove 41 Inner peripheral side uneven part 42, 42a Inner peripheral side concave part 43 Abutment surface 44 Fixed cylinder part 45, 45a Female joint 46 Male joint 47 Male serration 48 Female serration 49 Slit 50 Collar 51 Screw Holes 52, 52a Welded bead part 53 Joint shaft part 54 Joint cylinder part 55 Male serration 56 Notch 57, 57a Circular concave groove 58, 58a to 58e Outer peripheral side uneven part 59, 59a, 59b Outer outer side convex part 60 Inclined surface 61, 61a microprotrusion
62, 62a Caulking part 63, 63a Recessed part 64 Large diameter part 65 Cylindrical part 66 Welded bead part 67 Convex part Main body 68, 68a Guide part

Claims (6)

A first shaft having a first tubular portion provided with an outer peripheral side concave-convex portion and an annular concave groove, each of which has a concave-convex shape in the circumferential direction on the outer peripheral surface.
A second shaft having an inner peripheral side uneven portion having an uneven shape in the circumferential direction on the inner peripheral surface and having a second tubular portion into which the first tubular portion is inserted.
It is provided on at least one of the outer surface of the outer peripheral side convex portion forming the outer peripheral side uneven portion and the inner surface of the inner peripheral side concave portion forming the inner peripheral side uneven portion, and the outer peripheral side uneven portion and the inner peripheral side are provided. It is provided with micro-projections that can be plastically deformed when engaging with the uneven portion.
The inner peripheral side uneven portion and the outer peripheral side uneven portion are engaged with each other in a state in which the microprojections are plastically deformed, and the outer peripheral surface of the first shaft and the axial end portion of the second cylinder portion. And is fixed by welding, and a plastically deformed portion formed by plastically deforming a portion of the inner peripheral surface of the second tubular portion that matches the annular concave groove in the axial direction so as to project inward in the radial direction. A coupling structure between shafts in which the above-mentioned annular groove is arranged inside the annular groove. The first aspect of the present invention, wherein the minute protrusions are provided on the outer peripheral side convex portions arranged at every other or a plurality of times in the circumferential direction among the plurality of outer peripheral side convex portions constituting the outer peripheral side uneven portion. The described shaft-to-shaft coupling structure. Among the plurality of outer peripheral side convex portions, one microprojection is provided on each outer surface of three or more outer peripheral side convex portions arranged at equal intervals in the circumferential direction of the first tubular portion. , The coupling structure between the shafts according to claim 2. Of the plurality of outer peripheral convex portions, at least two outer peripheral convex portions arranged at positions opposite to each other in the radial direction of the first tubular portion are provided with two microprojections each. The coupling structure between the shafts according to claim 2. Of the plurality of outer peripheral side convex portions constituting the outer peripheral side concave-convex portion, the front end portion in the insertion direction into the inner peripheral side concave portion is radially outward in the insertion direction as compared with the rear side portion. The coupling structure between shafts according to any one of claims 1 to 4, wherein a guide portion having a small protrusion amount is provided. The first tubular portion constituting the first shaft, which is provided with an outer peripheral side uneven portion having a concave-convex shape in the circumferential direction and an annular concave groove on the outer peripheral surface, respectively, is provided on the inner peripheral surface on the inner peripheral side of the concave-convex shape in the circumferential direction. Insert it inside the second cylinder portion constituting the second shaft provided with the uneven portion until a part of the outer peripheral surface of the first cylinder portion abuts on a part of the inner peripheral surface of the second cylinder portion. In a state in which microprojections provided on at least one of the outer surface of the outer peripheral convex portion forming the outer peripheral side concave-convex portion and the inner surface of the inner peripheral side concave portion forming the inner peripheral side concave-convex portion are plastically deformed. After engaging the uneven portion on the outer peripheral side with the uneven portion on the inner peripheral side, the outer peripheral surface of the second cylinder portion is crushed inward in the radial direction to be arranged inside the annular concave groove. As described above, after forming a caulking portion that protrudes inward in the radial direction on the inner peripheral surface of the second tubular portion to suppress rattling in the axial direction between the first shaft and the second shaft, the above A method of connecting shafts to each other by welding and fixing the first shaft and the second shaft.

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