Yoke cover

Abstract

To provide a yoke cover capable of preventing the peripheral edge of an end face on the opposite side to a pair of yoke arm parts in the axial direction, out of a yoke base part as part of a yoke, from contacting an arm or leg of a human.SOLUTION: A yoke cover 1 includes a cover outer peripheral part 29 arranged around an other axial side portion of a yoke base part 14 for covering at least the end on the other axial side of the yoke base part 14 in the peripheral direction, and a stopper part 30 extending from the end on the other axial side of the cover outer peripheral part 29 to the radial inside and abutting on an end face 31 on the other axial side of the yoke base part 14, the cover outer peripheral part 29 having a snap fit piece 36 extending to one axial side, in a portion arranged on the radial outside of a pair of yoke flange parts 20a, 20b, the snap fit piece 36 having a claw part 37 protruding from the end on one axial side to the radial inside and engaging with a pair of extension parts 21a, 21b from one axial side.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a yoke cover that covers a yoke constituting a universal joint incorporated in a steering device for an automobile.

Background Art

[0002] In a steering device for an automobile, respective end portions of a steering shaft and an intermediate shaft that are not arranged on the same straight line are connected by a universal joint. Among the yokes constituting the universal joint, as a rear yoke coupled to the front end portion of the steering shaft, for example, a pinch bolt type yoke made of a metal material and manufactured by performing forging and cutting processes is used.

[0003] The yoke includes a yoke base portion and a pair of yoke arm portions. The yoke base portion has an inner peripheral surface that fits with the outer peripheral surface of the tip portion of the shaft and is configured in a cylindrical shape. The pair of yoke arm portions extend from two locations on the opposite side in the radial direction of the end portion on one axial side of the yoke base portion toward one axial side of the yoke base portion. Further, the yoke base portion has a slit that opens on both sides in the radial direction and on the other axial side at one location in the circumferential direction, a pair of yoke flange portions facing each other with the slit interposed therebetween, and a pair of bolt holes penetrating the pair of yoke flange portions.

[0004] When coupling the front end portion of the steering shaft to such a yoke, the front end portion of the steering shaft is inserted into the inside of the yoke base portion from the other axial side of the yoke base portion. Then, by tightening bolts inserted or screwed into the pair of bolt holes, the inner peripheral surface of the yoke base portion is reduced in diameter, and the inner peripheral surface is brought into pressure contact with the outer peripheral surface of the front end portion of the steering shaft.

[0005] Conventionally, various structures of yoke covers have been proposed for assembling the tip portion of the shaft to the yoke in a proper positional relationship (see, for example, Japanese Patent Application Laid-Open No. 2008-202742, Japanese Patent Application Laid-Open No. 2009-108875, and Japanese Patent No. 5223914). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2008-202742 [Patent Document 2] Japanese Patent Publication No. 2009-108875 [Patent Document 3] Patent No. 5223914 [Overview of the project] [Problems that the invention aims to solve]

[0007] In passenger car steering systems, the universal joint connecting the steering shaft and the intermediate shaft is usually located inside the steering column's under cover and is not exposed to the passenger compartment. Therefore, this universal joint does not come into contact with, for example, the driver's feet or with people's hands during cleaning of the passenger compartment.

[0008] In contrast, in steering systems for commercial vehicles, the universal joint connecting the steering shaft and the intermediate shaft is sometimes positioned exposed on the passenger side. In recent years, in such cases, it has been proposed to adequately prevent the driver's foot or other body parts from coming into contact with the corners on the periphery of the other end face of the yoke base of the rear yoke, which is coupled to the front end of the steering shaft.

[0009] One possible preventative measure is to use a yoke cover that is assembled to the yoke. However, conventional yoke covers have a structure specifically designed to prevent incorrect assembly of the shaft end to the yoke, and do not have a structure that can adequately prevent the driver's foot or other body parts from coming into contact with the corners on the periphery of the other end face on the axial side of the yoke base. In other words, when a conventional yoke cover is assembled to the yoke, at least a portion of the corners on the periphery of the other end face on the axial side of the yoke base is exposed to the outside of the yoke cover.

[0010] The present invention aims to provide a yoke cover that can prevent the peripheral edge of the end face opposite to the pair of yoke arms in the axial direction of the yoke base that constitutes the yoke from coming into contact with a person's hands, feet, etc. [Means for solving the problem]

[0011] A yoke for a universal joint to which a yoke cover according to one aspect of the present invention is assembled comprises a cylindrical yoke base having an inner circumferential surface that fits with the outer circumferential surface of the tip of a shaft, and a pair of yoke arms extending from two locations on the radially opposite side of one axial end of the yoke base toward one axial side of the yoke base, wherein the yoke base has a slit that opens radially on both sides and axially on the other side at one circumferential location, a pair of yoke flange portions facing each other on the other axial side with the slit in between, and a pair of bolt holes passing through the pair of yoke flange portions, wherein the pair of yoke flange portions has a pair of overhangs that protrude radially outward from the axial side portion of the yoke base, the shafts of bolts are inserted through or screwed into the pair of bolt holes, and the heads of the bolts abut against the outer surface of one of the yoke flange portions constituting the pair of yoke flange portions.

[0012] A yoke cover according to one aspect of the present invention comprises a cover outer periphery disposed around the other axial portion of the yoke base and covering at least the other axial end of the yoke base in the circumferential direction, and a stopper portion extending radially inward from the other axial end of the cover outer periphery and contacting the other axial end face of the yoke base. The cover outer periphery has snap-fit ​​pieces extending axially inward in portions disposed radially outward of the pair of yoke flange portions. The snap-fit ​​pieces have claw portions that protrude radially inward from the one axial end and engage with the pair of protruding portions from the one axial side.

[0013] In one embodiment of the present invention, the axial portion of the radially inner surface of the claw portion is composed of a one-sided inclined surface that is inclined radially outward as it moves toward the axial side.

[0014] In one embodiment of the present invention, the axially opposite portion of the radially inner surface of the claw portion is composed of an inclined surface on the other side that is inclined radially outward as it moves toward the other side in the axial direction.

[0015] In one embodiment of the present invention, the outer periphery of the cover has a protruding boss portion and / or the tip of the shaft portion protruding from the bolt hole on the outer surface of the other yoke flange portion constituting the pair of yoke flange portions, or the tip of the shaft portion and a nut that is screwed onto the tip and contacts the outer surface of the other yoke flange portion, and has a protruding cover portion that covers the protruding portion from the radially outward direction at a position that aligns with the protruding portion.

[0016] In one embodiment of the present invention, the yoke cover has a head circumference portion which, when viewed from the axial direction of the bolt, is arranged around the head of the bolt, and whose radially outer surface is arranged radially outward from the head.

[0017] In the yoke cover according to one aspect of the present invention, the outer peripheral portion of the cover has a wide portion having a larger radial width at at least one location in the circumferential direction of the end face on one side in the axial direction than the portions adjacent in the circumferential direction.

[0018] In the yoke cover according to one aspect of the present invention, the outer peripheral portion of the cover does not have a sharp corner over the entire circumference at the radially outer end of the end on the other side in the axial direction. That is, in the yoke cover of this aspect, the outer peripheral portion of the cover either does not have a corner at the radially outer end of the end on the other side in the axial direction, or even if it has a corner, the corner has an R shape. The radius of curvature of the R shape is preferably 1.0 mm or more, and more preferably 2.5 mm or more.

[0019] The present invention can be implemented by appropriately combining the configurations of the yoke covers of the above-described aspects within a range where no contradiction occurs.

Advantages of the Invention

[0020] According to the yoke cover of one aspect of the present invention, it is possible to prevent the peripheral edge of the end face on the side opposite to the pair of yoke arms in the axial direction of the yoke base constituting the yoke from being touched by a person's hand, foot, etc.

Brief Description of the Drawings

[0021] [Figure 1] FIG. 1 is a diagram schematically showing a steering device to which a yoke cover according to a first example of an embodiment of the present invention is assembled. [Figure 2] FIG. 2 is a perspective view of a yoke with a first example of a yoke cover and bolts assembled thereto, viewed from one side in the axial direction. [Figure 3] FIG. 3(a) is a side view of a yoke with a first example of a yoke cover and bolts assembled thereto, and FIG. 3(b) is a side view of the yoke viewed from the opposite side of FIG. 3(a). [Figure 4] FIG. 4(a) is a view seen from above FIG. 3(a), and FIG. 4(b) is a view seen from below FIG. 3(a). [Figure 5]Fig. 5(a) is a sectional view taken along the line A-A of Fig. 3(a), and Fig. 5(b) is a view seen from the right side (the other side in the axial direction) of Fig. 3(a). [Figure 6] Fig. 6 is a perspective view of the yoke cover of the first example seen from one side in the axial direction. [Figure 7] Fig. 7(a) is a side view of the yoke cover of the first example, and Fig. 7(b) is a side view of the yoke cover seen from the opposite side of Fig. 7(a). [Figure 8] Fig. 8(a) is a view seen from above Fig. 7(a), and Fig. 8(b) is a view seen from below Fig. 7(a). [Figure 9] Fig. 9(a) is a view seen from the left side (one side in the axial direction) of Fig. 7(a), and Fig. 9(b) is a view seen from the right side (the other side in the axial direction) of Fig. 7(a). [Figure 10] Figs. 10(a) and 10(b) are sectional views showing the process of manufacturing the yoke cover of the first example by injection molding in order of steps. [Figure 11] Fig. 11 is a perspective view of the yoke cover of the second example of the embodiment of the present invention and the yoke assembled with bolts seen from one side in the axial direction. [Figure 12] Fig. 12(a) is a view corresponding to the right half of Fig. 3(a) for the second example, and Fig. 12(b) is a view corresponding to Fig. 5(a) for the second example. [Figure 13] Fig. 13 is a perspective view of the yoke cover of the second example seen from one side in the axial direction. [Figure 14] Fig. 14(a) is a view corresponding to Fig. 7(a) for the second example, and Fig. 14(b) is a view seen from the left side of Fig. 14(a).

Embodiment for Carrying out the Invention

[0022] [First Example] The first example of the embodiment of the present invention will be described with reference to Figs. 1 to 10.

[0023] Figure 1 is a schematic diagram showing the steering device 2 for an automobile to which the yoke cover 1 (see Figures 2 to 5(b)) of this example is assembled.

[0024] In the following explanation in this example, the front-rear direction refers to the front-rear direction of the vehicle, the up-down direction refers to the up-down direction of the vehicle, and the left-right direction refers to the width direction of the vehicle.

[0025] The steering device 2 in this example comprises a steering wheel 3, a steering shaft 4, a steering column 5, a pair of universal joints 6a and 6b, an intermediate shaft 7, and a steering gear unit 8.

[0026] The steering wheel 3, which is rotated by the driver, is attached to the rear end of the steering shaft 4. The steering shaft 4 is rotatably supported inside the steering column 5, which is supported by the vehicle body. The front end of the steering shaft 4 is connected to the pinion shaft 9 of the steering gear unit 8 via a universal joint 6a, an intermediate shaft 7, and another universal joint 6b. The pinion shaft 9 meshes with the rack 10 of the steering gear unit 8. Therefore, when the driver rotates the steering wheel 3, the rotation of the steering wheel 3 is transmitted to the pinion shaft 9. The rotation of the pinion shaft 9 is then converted into linear motion of the rack 10. As a result, a pair of tie rods 11 connected to both ends of the rack 10 are pushed and pulled, and a steering angle corresponding to the amount of rotation of the steering wheel 3 is applied to the left and right steering wheels 12.

[0027] Although not shown in the diagram, the steering device 2 can provide assist driving force from an electric or hydraulic assist device to any of the steering force transmission members, such as the steering shaft 4, pinion shaft 9, or rack 10, in order to reduce the force required to rotate the steering wheel 3.

[0028] In this example, the yoke cover 1 is assembled to one of the yokes 13 that constitute the universal joint 6a, specifically the yoke 13 connected to the front end of the steering shaft 4. The universal joint 6a is constructed by connecting one yoke 13 and the other yoke (not shown) connected to the rear end of the intermediate shaft 7 via a cross shaft (not shown).

[0029] In the following description of the yoke 13 and yoke cover 1, one axial side is the left side in Figures 3(a), 4(a), 4(b), 7(a), 8(a), and 8(b), and the other axial side is the right side in these figures.

[0030] As shown in Figures 2 to 5(b), the yoke 13 in this example is manufactured by forging and machining a metal material and comprises a cylindrical yoke base 14 and a pair of yoke arms 15. The pair of yoke arms 15 extend from two locations on the radially opposite side of one axial end of the yoke base 14, toward one axial side of the yoke base 14. Each of the yoke arms 15 has a circular hole 16 at its tip that is arranged coaxially with respect to the other. The ends of the cross shaft are rotatably supported inside these circular holes 16 via needle bearings.

[0031] The yoke base 14 has an inner circumferential surface 18 that fits with the outer circumferential surface 17 of the front end, which is the tip of the steering shaft 4 (see Figure 3(a)). In this example, male serrations are formed on the outer circumferential surface 17 of the front end of the steering shaft 4, and female serrations that can engage with the male serrations are formed on the inner circumferential surface 18 of the yoke base 14.

[0032] The yoke base 14 has a slit 19 at one circumferential location on the other half of the axial side, which opens on both the radial side and the other axial side.

[0033] The yoke base 14 has a pair of yoke flange portions 20a and 20b facing each other across the slit 19. The pair of yoke flange portions 20a and 20b have a pair of overhangs 21a and 21b on their radially outer portions that extend radially outward from one axial half of the yoke base 14.

[0034] The yoke base 14 has a pair of bolt holes 22a, 22b that pass through a pair of yoke flange portions 20a, 20b. One bolt hole 22a that passes through one yoke flange portion 20a (lower side in Figure 4(a), right side in Figure 5(a), left side in Figure 5(b)) and the other bolt hole 22b that passes through the other yoke flange portion 20b (upper side in Figure 4(a), left side in Figure 5(a), right side in Figure 5(b)) are coaxially arranged. At least a portion of the pair of bolt holes 22a, 22b is formed in a pair of protruding portions 21a, 21b and is located radially outward from one axial half of the yoke base 14. In this example, one bolt hole 22a is configured as a through hole for inserting the shaft portion 24 of a bolt 23. The other bolt hole 22b is configured as a female threaded hole for screwing the shaft portion 24 of a bolt 23.

[0035] On the outer surface of one yoke flange portion 20a, the portion surrounding the opening of one bolt hole 22a is used as a seating surface against which the inner surface of the bolt head 25 of the bolt 23 abuts. On the outer surface of the other yoke flange portion 20b, the portion surrounding the other bolt hole 22b has a cylindrical boss portion 26 that protrudes more in the axial direction of the bolt hole 22b than the other portion.

[0036] As the yoke to which the yoke cover of the present invention is attached, a yoke can be used in which each of the bolt holes constituting a pair of bolt holes is configured as a through hole. In this case, a boss portion is not provided on the outer surface of the other yoke flange in the area surrounding the opening of the other bolt hole, and a nut is screwed onto the tip of the bolt shaft protruding from the other bolt hole. The area surrounding the opening of the other bolt hole on the outer surface of the other yoke flange is used as a seating surface for which the inner surface of the nut abuts. As the yoke to which the yoke cover of the present invention is attached, a yoke can also be used in which the phase of the arrangement of the pair of yoke arms in the circumferential direction of the yoke base is shifted by an arbitrary angle (for example, about 90°) with respect to the yoke 13 of this example.

[0037] With the front end of the steering shaft 4 (see Figure 3(a)) connected to the yoke 13, the front end of the steering shaft 4 is inserted into the inside of the yoke base 14 from the other axial side of the yoke base 14. A notched bolt engagement portion 27 is provided at one location in the circumferential direction on the outer surface of the front end of the steering shaft 4 and is positioned to align with a pair of bolt holes 22a and 22b. The shaft portion 24 of the bolt 23 is inserted through or screwed into the pair of bolt holes 22a and 22b. Specifically, the shaft portion 24 of the bolt 23 inserted through one bolt hole 22a is screwed into the other bolt hole 22b. The middle portion of the shaft portion 24 engages with the bolt engagement portion 27. This prevents the front end of the steering shaft 4 from coming out axially from the inside of the yoke base 14. The bolt 23 is tightened with the inner surface of the head 25 of the bolt 23 in contact with the outer surface of one yoke flange portion 20a. As a result, the inner circumferential surface 18 of the yoke base 14 is reduced in diameter, and this inner circumferential surface 18 is pressed against the outer circumferential surface 17 of the front end of the steering shaft 4. Specifically, the female serrations on the inner circumferential surface 18 are strongly engaged with the male serrations on the outer circumferential surface 17. This connects the front end of the steering shaft 4 to the yoke 13 in a way that allows for torque transmission.

[0038] Furthermore, in this state, as shown in Figures 4(a), 4(b), 5(a), and 5(b), the tip of the shaft portion 24 of the bolt 23 protrudes slightly outside the boss portion 26. In this example, the boss portion 26 and the tip of the shaft portion 24 constitute the convex portion 28. When implementing the present invention, the boss portion 26 can be omitted, and the convex portion can be formed by the tip of the shaft portion 24 protruding from the other bolt hole 22b. Furthermore, when implementing the present invention, as described above, if a configuration in which a nut is screwed onto the tip of the shaft portion of the bolt is adopted, the tips of these shaft portions and the nut constitute the convex portion.

[0039] In this example, the yoke cover 1 is attached to the yoke 13, as shown in Figures 2 to 5(b). Figures 6(a) to 9(b) show the yoke cover 1 in this example in its standalone state.

[0040] The yoke cover 1 in this example is made entirely of synthetic resin and comprises a cover outer circumference 29 and a stopper portion 30.

[0041] The outer periphery of the cover 29 is positioned around the other axial side portion of the yoke base 14 and covers at least the other axial end of the yoke base 14 in the circumferential direction. When carrying out the present invention, it is preferable that the outer periphery of the cover covers at least the other axial end of the yoke base 14 over its entire circumference. However, notches or holes can be formed in a part of the outer periphery of the cover that covers the other axial end of the yoke base in the circumferential direction. The stopper portion 30 extends radially inward from the other axial end of the outer periphery of the cover 29 and abuts against the other axial end face 31 of the yoke base 14, thereby axially positioning the yoke cover 1 relative to the yoke 13.

[0042] In this example, the outer periphery of the cover 29 is configured to be cylindrical overall. When viewed from the axial direction, the outer periphery of the cover 29 has a shape that generally follows the outer circumferential surface of the yoke base 14, that is, the side facing the slit 19 is roughly rectangular, and the side opposite the slit 19 is semi-cylindrical. The outer periphery of the cover 29 is fitted onto the other axial side of the yoke 13 to which the bolt 23 is attached, without any rattle.

[0043] The outer periphery of the cover 29 has an annular portion 32 that extends around its entire circumference at the other end on the axial side. The annular portion 32 is positioned to cover the entire circumference of the other end on the axial side of the yoke base 14, and more specifically, to cover up to the other edge on the axial side of the yoke base 14. In this example, the annular portion 32 covers the entire circumference of the other axial side portion of the yoke base 14 that is located on the other axial side of the head 25 of the bolt 23. When carrying out the present invention, the axial range of the portion of the other axial side portion of the yoke base 14 that is covered from the radially outside by the annular portion can be made wider or narrower than in this example. In this example, the other axial end of the annular portion 32 has a chamfered portion 51 on its outer circumferential surface, which will be described later, and is composed of a curved portion having a quarter-circular arc cross-sectional shape. The other axial edge of the curved portion, that is, the other axial edge of the outer periphery of the cover 29, is positioned on the other axial side of the other axial edge of the yoke base 14.

[0044] The outer periphery of the cover 29 has two notches 33 and 34 in the circumferential direction within the axial range, located on one axial side of the annular portion 32, each opening on one axial side.

[0045] One of the notches 33 extends over a wide circumferential range, from a position aligned with the outer widthwise portion of the radially outer surface of one of the yoke flange portions 20a to a position aligned with the head 25 of the bolt 23. The head 25 of the bolt 23 is positioned inside one of the notches 33. The inner end of one of the notches 33, which is the other axial end, is formed by an arc-shaped recess 35 that curves along the outer circumference of the head 25, and aligns with the head 25 of the bolt 23. A portion of the head 25 is positioned inside the recess 35.

[0046] The other notch 34 is located in a position that aligns with the midpoint of the widthwise portion of the radially outer surface of the other yoke flange portion 20b with respect to the circumferential direction.

[0047] The outer periphery 29 of the cover is located radially outward from a pair of yoke flange portions 20a and 20b, and has a snap-fit ​​piece 36 extending axially in one direction in the portion sandwiched between two notches 33 and 34. The snap-fit ​​piece 36 has a claw portion 37 projecting radially inward from one end on the axial side. The claw portion 37 engages with a pair of protruding portions 21a and 21b of the pair of yoke flange portions 20a and 20b from one side on the axial side. This prevents the yoke cover 1 from being displaced axially in the other direction relative to the yoke 13 and falling off.

[0048] When implementing the present invention, the shape of the claw portion of the snap-fit ​​piece is arbitrary as long as it can engage with a pair of protruding portions from one axial side. In this example, the claw portion 37 has a triangular shape when viewed from the axial direction of the bolt 23, as shown in Figure 3(a).

[0049] In other words, of the radially inner surface of the claw portion 37, the axially oriented portion is composed of a one-sided inclined surface 38 that is inclined radially outward as it moves toward the axially oriented side. In this example, the one-sided inclined surface 38 is composed of a flat surface, but it can also be composed of a concave or convex curved surface. The one-sided inclined surface 38 functions as a guide surface for the claw portion 37 to ride up onto the radially outer surfaces of the pair of yoke flange portions 20a and 20b when the outer circumference 29 of the cover is inserted around the yoke base 14 from the other axial side.

[0050] Of the radially inner surface of the claw portion 37, the portion on the other axial side is composed of a other-side inclined surface 39 that is inclined radially outward as it extends toward the other axial side. The axial end of the other-side inclined surface 39 on the other axial side is connected to the axial end of the portion of the radially inner surface of the snap-fit ​​piece 36 that is located on the other axial side of the claw portion 37. In this example, the other-side inclined surface 39 is composed of a concave curved surface, but it can also be composed of a flat surface or a convex curved surface. In this example, the other-side inclined surface 39 abuts against a pair of protruding portions 21a and 21b of a pair of yoke flange portions 20a and 20b. In this example, the one-side inclined surface 38 and the other-side inclined surface 39 are arranged adjacent to each other, but a flat surface or the like extending in the axial direction can also be provided between the one-side inclined surface 38 and the other-side inclined surface 39.

[0051] In this example, the outer periphery 29 of the cover has a protrusion covering portion 40 that covers the protrusion 28 from the radially outside, at a position aligned with the protrusion 28. As shown in Figures 5(a) and 5(b), the protrusion covering portion 40 protrudes radially outward from the outer periphery 29 of the cover compared to adjacent portions in the circumferential direction. When implementing the present invention, the shape of the protrusion covering portion is arbitrary as long as it can cover the protrusion from the radially outside, but in this example, the protrusion covering portion 40 has a trapezoidal shape when viewed from the axial direction. When implementing the present invention, the protrusion covering portion 40 can be omitted, and the protrusion 28 can be exposed to the outside of the yoke cover 1.

[0052] In this example, the outer periphery of the cover 29 has a wider portion 41 on one axial end face, located on the radially opposite side to the snap-fit ​​piece 36, which is wider in the radial direction than the adjacent portion in the circumferential direction. The wider portion 41 protrudes only radially outward compared to the adjacent portion in the circumferential direction. In this example, to form the wider portion 41, a projection 50 is provided that protrudes radially outward from the portion of the outer periphery of the cover 29 on one axial end face, located on the radially opposite side to the snap-fit ​​piece 36. The axial end face of this projection 50 is made part of the wider portion 41. As shown in Figure 3(a), the radially outer surface of the projection 50 is inclined radially inward as it moves toward the other axial side. In this example, the wider portion 41 is used as a point to be pressed by an ejector pin, which will be described later. When implementing the present invention, any structure can be adopted for the elements constituting the wider portion on the axial end face. For example, instead of the projection 50, a ridge that protrudes radially inward and extends axially can be provided, and the end face on one axial side of the ridge can be made part of the wider portion.

[0053] When implementing the present invention, the outer periphery of the cover can also consist only of an annular portion 32 and a snap-fit ​​piece 36 extending axially from a part of the annular portion 32 in the circumferential direction.

[0054] In this example, the stopper portion 30 is configured as an inward-facing flange extending radially inward from the entire circumference of the other axial end of the outer peripheral portion 29 of the cover. When viewed from the axial direction, the stopper portion 30 has an inner circumference shape that is substantially rectangular on the side facing the slit 19 and semicircular on the side opposite the slit 19. When implementing the present invention, the stopper portion can be provided at only one or more locations in the circumferential direction. The shape of the stopper portion can be any shape as long as interference with the front end of the steering shaft is avoided.

[0055] In this example, the outer circumference 29 of the cover does not have a sharp corner along its entire circumference at the radially outer end of the other axial end.

[0056] Specifically, in this example, the outer surface of the outer periphery of the cover 29 has corners when viewed from the other axial side, that is, in Figure 5(b), at both ends in the left-right direction of the upper end and at both ends on the upper and lower sides of the tip (right end) of the protruding cover portion 40. However, these corners are not sharp and have a large radius of curvature (R shape). The radius of curvature of the R shape is preferably 2.5 mm or more, and more preferably 5.0 mm or more.

[0057] A chamfered portion 51 with a large radius of curvature (R-shape) is provided at the axial end of the outer circumferential surface of the annular portion 32 that constitutes the outer circumferential portion 29 of the cover. The radius of curvature of the R-shape is preferably 1.0 mm or more, and more preferably 2.5 mm or more. The radially inner end of the chamfered portion 51 is connected to the radially outer end of the axially opposite side surface of the stopper portion 30.

[0058] In the structure of this example, for example, after assembling the yoke cover 1 to the yoke 13, the front end of the steering shaft 4 can be connected to the yoke 13 using bolts 23.

[0059] When assembling the yoke cover 1 to the yoke 13, the outer circumference 29 of the cover is inserted around the yoke base 14 from the other axial side. The stopper portion 30 is then brought into contact with the other axial end face 31 of the yoke base 14, and the claw portion 37 is engaged with the pair of protruding portions 21a and 21b of the pair of yoke flange portions 20a and 20b from one axial side.

[0060] In this example, when inserting the outer circumference 29 of the cover around the yoke base 14 from the other axial side, the snap-fit ​​piece 36 elastically deforms radially outward as the inclined surface 38 on one side of the claw portion 37 is guided by the other axial edge of the radially outer surface of the pair of yoke flange portions 20a and 20b, causing the claw portion 37 to ride up onto the radially outer surface of the pair of yoke flange portions 20a and 20b. This makes it easy to insert the outer circumference 29 of the cover around the yoke base 14 from the other axial side. The snap-fit ​​piece 36 elastically returns to its radially inward position once the claw portion 37 has passed the radially outer surface of the pair of yoke flange portions 20a and 20b in the axial direction. As a result, the claw portion 37 engages with the pair of protruding portions 21a and 21b of the pair of yoke flange portions 20a and 20b from one axial side.

[0061] In carrying out the present invention, a configuration can be adopted in which the claw portion does not have a sloping surface on one side that serves as a guide surface when inserted. In this case, for example, when inserting the outer circumference of the cover around the yoke base from the other side in the axial direction, the operator can elastically deform the snap-fit ​​piece radially outward by hand.

[0062] When connecting the front end of the steering shaft 4 to the yoke 13 to which the yoke cover 1 is assembled, first, the front end of the steering shaft 4 is inserted into the yoke base 14 from the other axial side, and the bolt engagement portion 27 provided at one location in the circumferential direction on the outer surface of the front end of the steering shaft 4 is positioned to align with a pair of bolt holes 22a and 22b. Next, the shaft portion 24 of the bolt 23 inserted through one bolt hole 22a is screwed into the other bolt hole 22b, and the middle portion of the shaft portion 24 is engaged with the bolt engagement portion 27 of the steering shaft 4. Then, with the inner surface of the head 25 of the bolt 23 in contact with the outer surface of one yoke flange portion 20a, the bolt 23 is tightened. This reduces the diameter of the inner circumferential surface 18 of the yoke base 14, and strongly engages the female serrations provided on the inner circumferential surface 18 with the male serrations provided on the outer surface 17.

[0063] In this example, the yoke cover 1 can also be attached to the yoke 13 after the front end of the steering shaft 4 has been connected to the yoke 13 using bolts 23. In this case, the yoke cover 1 is first positioned around the portion of the steering shaft 4 located behind the front end. Then, after connecting the front end of the steering shaft 4 to the yoke 13 using bolts 23, the yoke cover 1 is attached to the yoke 13 by inserting the outer circumference 29 of the cover around the yoke base 14 from the other axial side.

[0064] The yoke cover 1 in this example can be manufactured using an injection molding apparatus equipped with a first mold 42 and a second mold 43, as shown in Figure 10(a). The first mold 42 has a convex-shaped internal molding portion 44 that forms the internal shape of the yoke cover 1 (including the inner peripheral shape of the notches 33 and 34). The second mold 43 has a concave-shaped external molding portion 45 that forms the external shape of the yoke cover 1. The first mold 42 and the second mold 43 are capable of relative movement in the axial direction of the yoke cover 1.

[0065] When injection molding the yoke cover 1, first, as shown in Figure 10(a), heated and molten resin is poured through a gate (not shown) into a cavity for molding the yoke cover 1, which is defined between the inner molding portion 44 of the first mold 42 and the outer molding portion 45 of the second mold 43. Then, the yoke cover 1 is molded by cooling and solidifying the resin in the cavity.

[0066] Next, as shown in Figure 10(b), the mold is demolded by moving the second mold 43 axially away from the first mold 42 (or moving the first mold 42 axially away from the second mold 43). In this example, the portion of the yoke cover 1 sandwiched between the stopper portion 30 and the claw portion 37 in the axial direction is the undercut portion 46. Therefore, after demolding, the yoke cover 1 remains on the inner mold portion 44 side based on the engagement between the undercut portion 46 and the inner mold portion 44.

[0067] Next, the yoke cover 1 is pressed in the other axial direction by an ejector pin (not shown) provided in the first mold 42, thereby moving the yoke cover 1 in the other axial direction relative to the internal molded portion 44 and separating the yoke cover 1 from the internal molded portion 44.

[0068] When performing the separation operation of the yoke cover 1, the locations where the yoke cover 1 is pressed by the ejector pin are not particularly limited, as long as no problems such as damage to the yoke cover 1 occur during the operation. In this example, the locations where the yoke cover 1 is pressed by the ejector pin are the multiple locations (parts P) indicated by black circles in Figure 9(a). In particular, in this example, one of the locations is selected to be the end face on one axial side of the outer circumference 29 of the cover. More specifically, the wide portion 41 of the end face on one axial side of the outer circumference 29 of the cover is selected. This prevents problems such as deformation of the end on one axial side of the outer circumference 29 of the cover from occurring due to the force applied by the ejector pin. It is also possible to select multiple locations in the circumferential direction of the end face on one axial side of the outer circumference 29 of the cover as locations where the yoke cover 1 is pressed by the ejector pin. In this case, a wide portion can be provided at each of these locations.

[0069] In this example, when the yoke cover 1 is moved axially to the other side relative to the internal molded portion 44 as described above, the snap-fit ​​piece 36 elastically deforms radially outward as the other-side inclined surface 39 of the claw portion 37 is guided by the axial end of the undercut portion molding 47 of the internal molded portion 44, causing the claw portion 37 to ride up onto the radially outer surface of the undercut portion molding 47. Therefore, the operation of moving the yoke cover 1 axially to the other side relative to the internal molded portion 44 can be performed smoothly. Consequently, the yoke cover 1 in this example can be molded with a simple mold structure, thereby reducing manufacturing costs.

[0070] When implementing the present invention, it is also possible to adopt a configuration in which the claw portion does not have an inclined surface on the other side, and the end of the claw portion on the other axial side has a stepped surface facing the other axial side. In this case, when moving the yoke cover to the other axial side relative to the internally formed part, the snap-fit ​​piece can be elastically deformed radially outward using a jig or the like, thereby causing the claw portion to ride up onto the radially outer surface of the undercut portion forming part.

[0071] According to the yoke cover 1 in this example, it is possible to prevent the corner portion 52 (see Figures 3 to 5) located on the periphery of the end face 31 on the other axial side of the yoke base 14 that constitutes the yoke 13 from coming into contact with a person's hands or feet.

[0072] In other words, in the manufacturing of the yoke 13, the end face 31 is finished by machining, so the corners 52 on the periphery of the end face 31 become sharp. Therefore, it is desirable to prevent such corners 52 from coming into contact with a person's hands or feet. The yoke cover 1 in this example includes a cover outer periphery 29 that covers the entire circumference of the other axial end of the yoke base 14, and is positioned such that the other axial end face is located further axially than the other axial end face of the yoke base 14. Therefore, the corners 52 on the periphery of the other axial end face 31 of the yoke base 14 are not exposed to the outside of the cover outer periphery 29, but are positioned radially inward of the cover outer periphery 29. Therefore, it is possible to prevent the corners 52 from coming into contact with a person's hands or feet. Specifically, this prevents the corner portion 52 from touching the driver's feet, touching a person's hand when cleaning the interior of the vehicle, or touching the hand of a worker who connects the front end of the steering shaft 4 to the yoke 13 after assembling the yoke cover 1 to the yoke 13.

[0073] In this example, the outer circumference 29 of the cover does not have a sharp corner along its entire circumference at the radially outer end of the other axial end. Therefore, safety can be ensured in case the driver's foot or other body part comes into contact with the radially outer end of the other axial end of the outer circumference 29 of the cover.

[0074] In this example, the outer periphery 29 of the cover has a protrusion covering portion 40 that covers the protrusion 28 from the radially outer side at a position aligned with the protrusion 28. This prevents the driver's foot or other body parts from coming into contact with the protrusion 28. When implementing the present invention, a wall plate portion can also be provided on the outer periphery 29 of the cover, projecting outward in the axial direction of the bolt 23 from the portion of the notch 33 located around the head 25 of the bolt 23. The presence of this wall plate portion makes it more difficult for the driver's foot or other body parts to come into contact with the head 25.

[0075] In this example, the annular portion 32 and snap-fit ​​piece 36 of the yoke cover 1 cover the radially outer opening of the slit 19 of the yoke 13. Therefore, after assembling the yoke cover 1 to the yoke 13, it is possible to prevent the worker's hand from touching the radially outer opening edge of the slit 19 when connecting the front end of the steering shaft 4 to the yoke 13. In other words, in the manufacturing of the yoke 13, the slit 19 is finished by machining, so the radially outer opening edge of the slit 19 becomes a sharp corner. With the yoke cover 1 in this example, it is possible to prevent the worker's hand from touching such a corner.

[0076] Japanese Patent Publication No. 2008-202742 describes a structure in which, in order to prevent the yoke cover from coming off the yoke in the other axial direction, the claw portion at the tip of a snap-fit ​​piece extending from the other axial side of the yoke cover toward one axial direction engages from one axial side with a portion of the axial edge of the yoke base that is circumferentially away from a pair of yoke arms. However, in this structure, if the length of the snap-fit ​​piece increases, or if the circumferential position of the pair of yoke arms relative to the yoke base changes, it becomes necessary to change the circumferential position of the snap-fit ​​piece accordingly. In contrast, in this example, in order to prevent the yoke cover 1 from coming off the yoke cover 1 in the other axial direction with respect to the yoke 13, the claw portion 37 at the tip of a snap-fit ​​piece 36 extending from the other axial side of the yoke cover 1 toward one axial direction engages from one axial side with a pair of protruding portions 21a and 21b of a pair of yoke flange portions 20a and 20b. Therefore, the length of the snap-fit ​​piece 36 can be reduced compared to the structure described in Japanese Patent Publication No. 2008-202742. In addition, the yoke cover 1 can be attached to multiple yokes with different circumferential positions of a pair of yoke arms 15 relative to the yoke base 14 without changing the circumferential position of the snap-fit ​​piece 36.

[0077] [Example 2] A second example of an embodiment of the present invention will be described with reference to Figures 11 to 14(b).

[0078] In this example, the notch 33a on the outer circumference 29a of the yoke cover 1a, adjacent to the bolt head 25 side relative to the snap-fit ​​piece 36, is located in a position that aligns with the middle of the widthwise side of the radially outer surface of one of the yoke flange portions 20a. That is, in this example, the circumferential width of the notch 33a is smaller than in the first example.

[0079] In this example, the outer periphery of the cover 29a has a notch 48 that opens on one side in the axial direction, at a position that aligns with the head 25 of the bolt 23. As shown in Figure 12(a), when viewed from the axial direction of the bolt 23, the head 25 is located inside the notch 48 and is not covered from the radially outer side by the outer periphery of the cover 29a. The outer periphery of the cover 29a has a head circumference portion 49 around the notch 48, which is positioned around the head 25 of the bolt 23 when viewed from the axial direction of the bolt 23. As shown in Figure 12(b), the radially outer surface of the head circumference portion 49 is positioned radially outward from the head 25. Therefore, in this example, the presence of the head circumference portion 49 prevents the driver's foot or other objects from hitting the head 25.

[0080] When manufacturing the yoke cover 1a in this example by injection molding, multiple circumferential locations on one axial end face of the outer peripheral portion 29a of the cover, for example, the multiple α portions shown in Figure 14(b), can be used as pressing portions by the ejector pin. In this case, a wide portion can be provided for each of the α portions. The other configurations and effects are the same as in the first example. [Explanation of Symbols]

[0081] 1, 1a Yoke cover 2. Steering system 3. Steering Wheel 4. Steering shaft 5. Steering column 6a, 6b Universal joint 7 Intermediate shaft 8. Steering Gear Unit 9 Pinion shaft 10 racks 11 Tie Rod 12 Steering wheels 13 York 14 Yoke base 15. Yoke Arm 16 circular hole 17 Outer surface 18 Inner surface 19 slits 20a, 20b Yoke flange section 21a, 21b Overhang 22a, 22b Bolt holes 23 volts 24 Shaft section 25 Head 26 Boss Section 27 Bolt engagement part 28 Convex part 29, 29a Outer periphery of the cover 30 Stopper section 31 End face 32 Ring section 33, 33a Notch 34 Notches 35 recess 36 snap-fit ​​pieces 37. Nail area 38 One side slope 39 Other side slope 40 Convex part covering 41 Wide section 42. First mold 43. Second mold 44 Internal molding section 45 External shaping part 46 Undercut section 47 Undercut molding section 48 Notches 49. Head circumference 50 protrusions 51 Chamfered section 52 corners

Claims

1. a cylindrical yoke base having an inner peripheral surface that mates with the outer peripheral surface of the tip end of a shaft; and a pair of yoke arms extending from two radially opposite locations on one axial end of the yoke base to one axial side of the yoke base, the yoke base having a slit that opens to both radial sides and the other axial side at one circumferential location, a pair of yoke flanges that face each other across the slit at the other axial side, and a pair of bolt holes that pass through the pair of yoke flanges, the pair of yoke flanges having a pair of overhanging portions that overhang radially outward beyond the one axial side of the yoke base, and bolt shanks that are inserted or screwed into the pair of bolt holes, and the yoke cover is assembled to a universal joint yoke in which the head of the bolt abuts against the outer surface of one of the pair of yoke flanges, a cover outer circumferential portion disposed around the other axial side portion of the yoke base and circumferentially covering at least the other axial side end portion of the yoke base; a stopper portion extending radially inward from the other axial end of the outer circumferential portion of the cover and abutting against the other axial end face of the yoke base, the outer circumferential surface of the cover has a snap-fit ​​piece extending toward one axial side at a portion disposed radially outward of the pair of yoke flange portions, The snap-fit ​​piece has a claw portion that protrudes radially inward from an end portion on one axial side and engages with the pair of overhanging portions from one axial side. Yoke cover.

2. 2. The yoke cover according to claim 1, wherein one axial side portion of the radially inner surface of the claw portion is configured as a one-side inclined surface that is inclined radially outward as it approaches the one axial side.

3. 2. The yoke cover according to claim 1, wherein the other axial side portion of the radially inner surface of the claw portion is configured as an other-side inclined surface that is inclined radially outward as it approaches the other axial side.

4. 2. The yoke cover according to claim 1, wherein the outer circumferential surface of the cover has a protrusion covering portion that covers the protrusion from the radially outer side at a position aligned with a protrusion formed by a boss portion that protrudes from the outer surface of the other of the pair of yoke flange portions around the bolt hole and / or a tip portion of the shaft portion that protrudes from the bolt hole, or a nut that threads onto the tip portion of the shaft portion and abuts against the outer surface of the other of the pair of yoke flange portions.

5. 2. The yoke cover according to claim 1, wherein the cover outer peripheral portion has a head peripheral portion that is arranged around the head of the bolt when viewed in the axial direction of the bolt and has a radially outer surface that is arranged radially outward from the head.

6. 2. The yoke cover according to claim 1, wherein the outer circumferential portion of the cover has a wide portion at at least one circumferential location on an end surface on one axial side, the wide portion having a radial width greater than that of a portion adjacent thereto in the circumferential direction.

7. 7. The yoke cover according to claim 1, wherein the outer circumferential portion of the cover does not have any sharp corners along the entire circumference at the radially outer end of the other axial end.

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