JP7850596B2 - York cover - Google Patents

Description

This invention relates to a yoke cover that covers a yoke constituting a universal joint incorporated into an automobile steering system.

In automotive steering systems, the ends of the steering shaft and the intermediate shaft, which are not aligned on the same straight line, are connected by a universal joint. Among the yokes constituting this universal joint, the rear yoke connected to the front end of the steering shaft is typically a pinch bolt type yoke, made from a metal material through forging and machining.

The yoke comprises a yoke base and a pair of yoke arms. The yoke base has an inner circumferential surface that fits with the outer circumferential surface of the shaft's tip and is cylindrical in shape. The pair of yoke arms extend from two points on the radially opposite side of one axial end of the yoke base, towards the axial side of the yoke base. The yoke base also has a slit opening at one circumferential point on both radial and axial sides, a pair of yoke flanges facing each other across the slit, and a pair of bolt holes passing through the pair of yoke flanges.

When connecting the front end of the steering shaft to such a yoke, the front end of the steering shaft is inserted into the inside of the yoke base from the other axial side of the yoke base. Then, by tightening a bolt inserted or screwed into a pair of bolt holes, the inner circumferential surface of the yoke base is reduced in diameter, and this inner circumferential surface is pressed against the outer circumferential surface of the front end of the steering shaft.

Conventionally, various structures for yoke covers have been proposed to enable the shaft tip to be assembled to the yoke in the correct positional relationship (see, for example, Japanese Patent Publication No. 2008-202742, Japanese Patent Publication No. 2009-108875, and Japanese Patent No. 5223914).

Japanese Patent Publication No. 2008-202742 Japanese Patent Publication No. 2009-108875 Patent No. 5223914

In passenger car steering systems, the universal joint connecting the steering shaft and the intermediate shaft is typically 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.

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. Recently, 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 axial end face of the rear yoke, which is coupled to the front end of the steering shaft.

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 adequately prevents the driver's foot or other body parts from coming into contact with the corners on the periphery of the other axial end face 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 axial end face of the yoke base is exposed to the outside of the yoke cover.

The present invention aims to provide a yoke cover that prevents the peripheral edge of the end face opposite to the pair of yoke arms in the axial direction from coming into contact with a person's hands, feet, or other body parts.

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. The yoke base has a slit opening at one circumferential location on both radial sides and the other axial side, a pair of yoke flange portions facing each other across the slit on the other axial side, and a pair of bolt holes passing through the pair of yoke flange portions. The shafts of bolts are inserted through or screwed into the pair of bolt holes, and the heads of the bolts abut against the widthwise outer surface of one of the yoke flange portions, which is part of the outer circumferential surface of the other axial side portion of the yoke base.

A yoke cover according to one aspect of the present invention comprises a first cover plate portion and a pair of second cover plate portions, the base ends of which are pivotably connected to the widthwise ends of the first cover plate portion, and whose respective tip portions can be moved toward or toward each other based on this pivoting motion. The yoke cover can be configured in a closed state, where the first cover plate portion and the pair of second cover plate portions are connected in a cylindrical shape by bringing the tip portions of the pair of second cover plate portions closer together and engaging them, thereby creating a space radially inward; and an open state, where the tip portions of the pair of second cover plate portions are moved apart, opening the space. In the closed state, the axial opposite side of the yoke base portion is positioned within the space.

In one embodiment of the present invention, in the closed state, the first cover plate covers the circumferential portion of the outer circumferential surface of the axially opposite portion of the yoke base located between the openings of the pair of bolt holes. The pair of second cover plate portions covers the remaining circumferential portion of the outer circumferential surface.

In one embodiment of the present invention, in the closed state, the first cover plate covers the radially outer surface of the pair of yoke flanges on the outer circumferential surface of the other axial side portion of the yoke base. The pair of second cover plate covers the remaining circumferential portion of the outer circumferential surface, i.e., the widthwise outer surface of the pair of yoke flanges and the portion circumferentially offset from the pair of yoke flanges.

In one embodiment of the present invention, in the closed state, the first cover plate covers the portion of the outer circumferential surface of the axially opposite portion of the yoke base that is circumferentially separated from the pair of yoke flange portions. The pair of second cover plate portions cover the remaining circumferential portion of the outer circumferential surface, i.e., the widthwise outer surface of the pair of yoke flange portions and the radially outer surface of the pair of yoke flange portions.

In one embodiment of the present invention, a yoke cover is provided with a stopper portion connected to at least one of the axial ends of the first cover plate portion. In the closed state, the stopper portion engages axially with a pair of protruding portions of the pair of yoke flange portions that extend radially outward from one axial side portion of the yoke base portion.

In one embodiment of the present invention, a yoke cover is provided with a slit entry portion connected to the first cover plate portion and which enters the slit in the closed state. The slit entry portion opens radially inward from the yoke base portion and has a notched bolt engagement portion that engages with the shaft portion.

In one embodiment of the present invention, the yoke cover, of the pair of second cover plate portions, the second cover plate portion positioned on the head side with respect to the axial direction of the bolt, has a head insertion portion into which the head is inserted.

In one embodiment of the present invention, the inner side of the head insertion portion in the width direction when the head is closed has a concave shape into which the head is inserted, and the outer side of the head insertion portion in the width direction when the head is closed has a convex shape.

In one embodiment of the present invention, the yoke cover, of the pair of second cover plate portions, the second cover plate portion positioned opposite the bolt head with respect to the axial direction of the bolt, has a protrusion insertion portion into which a protrusion is inserted. This protrusion is formed by a boss portion and/or the tip of the shaft portion protruding from the bolt hole on the outer surface in the width direction of the other yoke flange portion of the pair of yoke flange portions, which is part of the outer surface of the other axial portion of the yoke base portion, or by the tip of the shaft portion and a nut that screws onto the tip and abuts against the outer surface in the width direction of the other yoke flange portion.

In one embodiment of the present invention, the inner side of the protrusion insertion portion in the width direction when closed has a concave shape into which the protrusion is inserted, and the outer side of the protrusion insertion portion in the width direction when closed has a convex shape.

In one embodiment of the present invention, the first cover plate portion and the pair of second cover plate portions each have a shape that, in the closed state, conforms circumferentially to the outer circumferential surface of the other axial portion of the yoke base.

The present invention can be implemented by appropriately combining the configurations of the yoke cover described in each of the above embodiments, within the limits that do not result in contradictions.

According to one embodiment of the present invention, the peripheral edge of the end face of the yoke base, which constitutes the yoke, opposite to the pair of yoke arms in the axial direction, can be prevented from coming into contact with a person's hands, feet, or other body parts.

Figure 1 is a schematic diagram showing a steering device to which a yoke cover of a first embodiment of the present invention is assembled. Figure 2 is a perspective view of the yoke with the yoke cover and bolts assembled in the first example, viewed from one side in the axial direction. Figure 3 is a perspective view of the yoke with the yoke cover and bolts assembled in the first example, seen from the opposite side of Figure 2. Figure 4(a) is a side view of the yoke with the yoke cover and bolts assembled according to the first example, and Figure 4(b) is a side view of the yoke as seen from the opposite side of Figure 4(a). Figure 5(a) is a view of Figure 4(a) from above, and Figure 5(b) is a view of Figure 4(a) from below. Figure 6(a) is a cross-sectional view taken along line A-A in Figure 4(a), and Figure 6(b) is a view of Figure 4(a) from the right side (the other side in the axial direction). Figure 7 is a perspective view of the first example of the yoke cover, viewed from one side in the axial direction. Figure 8 is a perspective view showing the yoke cover of the first example unfolded. Figure 9(a) is a plan view showing the yoke cover of the first example unfolded, and Figure 9(b) is a view of the yoke cover from below Figure 9(a). Figure 10 is a diagram relating to a second embodiment of the present invention, corresponding to the left half of Figure 3. Figure 11 is a diagram relating to a third embodiment of the present invention, corresponding to the left half of Figure 3.

[Example 1]
A first example of an embodiment of the present invention will be described with reference to Figures 1 to 9(b).

Figure 1 is a schematic diagram showing the steering device 2 for an automobile to which the yoke cover 1 (see Figures 2 to 6(b)) of this example is assembled.

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.

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.

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.

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

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 to the other yoke (not shown) connected to the rear end of the intermediate shaft 7 via a cross shaft (not shown).

In the following description of the yoke 13 and yoke cover 1, one axial side is the left side in Figures 4(a), 5(a), and 5(b), and the other axial side is the right side in these figures.

As shown in Figures 2 to 6(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, which is coaxially arranged with respect to the other. The ends of the cross shaft are rotatably supported inside these circular holes 16 via needle bearings.

The yoke base 14 has an inner circumferential surface 18 that engages with the outer circumferential surface 17 of the front end of the steering shaft 4 (see Figures 4(a) and 4(b)). 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 these male serrations are formed on the inner circumferential surface 18 of the yoke base 14.

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 and axial sides.

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 protruding portions 21a and 21b on their radially outer sides, extending radially outward from one axial half of the yoke base 14.

The yoke base 14 has a pair of bolt holes 22a and 22b that pass through a pair of yoke flange portions 20a and 20b. One bolt hole 22a that passes through one yoke flange portion 20a (lower side in Figure 5(b), left side in Figure 6(a), and right side in Figure 6(b)), and the other bolt hole 22b that passes through the other yoke flange portion 20b (upper side in Figure 5(b), right side in Figure 6(a), and left side in Figure 6(b)) are arranged coaxially with each other. At least a portion of the pair of bolt holes 22a and 22b is formed in a pair of protruding portions 21a and 21b, and is located radially outward from one half of the axial side 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 the bolt 23. The other bolt hole 22b is configured as a female threaded hole for screwing the shaft portion 24 of the bolt 23.

The outer surface of one yoke flange portion 20a, specifically the outer surface in the width direction (left-right direction in Figures 6(a) and 6(b)), which is a part of the outer surface of the other axial portion of the yoke base portion 14, is used as a seating surface for the inner surface of the bolt head 25 of the bolt 23. The other yoke flange portion 20b has a cylindrical boss portion 26 on its outer surface in the width direction, specifically the portion around the other bolt hole 22b, which protrudes more in the axial direction of the bolt hole 22b than the rest of the portion.

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 width direction, around the opening of the other bolt hole, and a nut is screwed onto the tip of the bolt shaft portion protruding from the other bolt hole. The outer surface of the other yoke flange in the width direction, around the opening of the other bolt hole, 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 of the yoke base in the circumferential direction is shifted by an arbitrary angle (for example, about 90°) with respect to the yoke 13 of this example.

With the front end of the steering shaft 4 (see Figures 4(a) and 4(b)) 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 a bolt 23 is inserted through or screwed into the pair of bolt holes 22a and 22b. Specifically, the shaft portion 24 of a bolt 23 inserted through one bolt hole 22a is screwed into the other bolt hole 22b. The middle portion of the shaft portion 24 is engaged 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 its head 25 in contact with the outer surface in the width direction of one of the yoke flange portions 20a. This causes the inner circumferential surface 18 of the yoke base 14 to shrink in diameter, and this inner circumferential surface 18 presses 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 strongly engage 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 torque-transmitting manner.

Furthermore, in this state, as shown in Figures 5(a), 5(b), 6(a), and 6(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. Note that 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, if a configuration is adopted in which a nut is screwed onto the tip of the bolt shaft portion, as described above, the tips of these shaft portions and the nut constitute the convex portion.

The yoke cover 1 in this example is attached to the yoke 13, as shown in Figures 2 to 6(b). Figures 7 to 9(b) show the yoke cover 1 in this example in its standalone state.

The yoke cover 1 in this example is entirely made of synthetic resin or synthetic rubber. The yoke cover 1 comprises a first cover plate portion 29 and a pair of second cover plate portions 30a and 30b, the base ends of which are pivotably connected to the ends on both sides of the first cover plate portion 29 in the width direction (left and right direction in Figures 9(a) and 9(b)), and whose respective tip portions can be moved toward and away from each other based on this pivoting. The yoke cover 1 can be configured in two states: a closed state (see Figure 7) where the front ends of a pair of second cover plate portions 30a and 30b are brought close together and engaged, forming a cylindrical body in which the first cover plate portion 29 and the pair of second cover plate portions 30a and 30b are connected in a cylindrical manner, creating an inward arrangement space S; and an open state (see Figures 8 to 9(b)) where the front ends of the pair of second cover plate portions 30a and 30b are moved apart, opening the arrangement space S. As shown in Figures 2 to 6(b), the yoke cover 1 is attached to the yoke 13 in the closed state. In this state, the axial opposite side portion of the yoke base portion 14 (including the axial opposite end face 31) is positioned within the arrangement space S.

In this example, the first cover plate portion 29 has a rectangular flat plate shape, as shown in Figures 8 to 9(b).

One of the second cover plate portions 30a has a flat, straight portion 32a on the base end half, which is closer to the first cover plate portion 29. The base end of the straight portion 32a is pivotably connected to one end of the first cover plate portion 29 in the width direction (the left side in Figures 9(a) and 9(b)) by an arbitrary structure. In this example, by bending the connection between the base end of the straight portion 32a and the end of the first cover plate portion 29 in the width direction—in other words, by making the connection function as a hinge—it is possible to pivot one of the second cover plate portions 30a relative to the first cover plate portion 29. In this example, the thickness of the connection is the same as the thickness of the first cover plate portion 29 and one of the second cover plate portions 30a. When implementing the present invention, the thickness of the connection can be made smaller than the thickness of the first cover plate portion and one of the second cover plate portions to make the connection easier to bend.

One of the second cover plate portions 30a has a partially cylindrical curved portion 33a on the tip side, which is the half furthest from the first cover plate portion 29. This curved portion has a concave inner surface (the upper surface in Figures 8 and 9(b)) that is positioned radially inward in the closed state (see Figure 7).

One of the second cover plate portions 30a has flange portions 34a that are bent at a right angle toward the inner surface at both axial ends of the mutually continuous straight portion 32a and curved portion 33a. The one of the second cover plate portions 30a is reinforced by these flange portions 34a.

One of the second cover plates, portion 30a, has a head insertion portion 35 located approximately in the center of the straight portion 32a, into which the head 25 of the bolt 23 is inserted. In the closed state, the inner side of the head insertion portion 35 in the width direction, i.e., the inner surface side, has a concave shape into which the head 25 is inserted, while the outer side of the head insertion portion 35 in the closed state, i.e., the outer surface side, has a convex shape. In this example, such a head insertion portion 35 is constructed in the shape of a bottomed cylindrical tube (a bottomed cone in the illustrated example).

One of the second cover plates 30a has a one-sided engaging portion 36 at the axial center of the tip of the curved portion 33a. The one-sided engaging portion 36 is positioned to protrude radially outward from the curved portion 33a. The one-sided engaging portion 36 has a snap-fit piece 37 that protrudes more than the tip surface of the curved portion 33a in the direction normal to the tip surface.

The other second cover plate portion 30b has a flat, straight portion 32b on the base end half, which is closer to the first cover plate portion 29. Similar to the first second cover plate portion 30a, the base end of the straight portion 32b is pivotably connected to the other end of the first cover plate portion 29 in the width direction (the right side in Figures 9(a) and 9(b)).

The other second cover plate portion 30b has a partially cylindrical curved portion 33b on the tip side, which is the half furthest from the first cover plate portion 29. This curved portion has a concave inner surface (the upper surface in Figures 8 and 9(b)) that is positioned radially inward in the closed state (see Figure 7).

The other second cover plate portion 30b has flange portions 34b that are bent at a right angle toward the inner surface at both axial ends of the mutually continuous straight portion 32b and curved portion 33b. The other second cover plate portion 30b is reinforced by these flange portions 34b.

The other second cover plate portion 30b has a protrusion insertion portion 38 located approximately in the center of the straight portion 32b into which the protrusion 28 is inserted. In the closed state, the inner side in the width direction of the protrusion insertion portion 38, i.e., the inner surface side, has a concave shape into which the protrusion 28 is inserted, while the outer side in the width direction of the protrusion insertion portion 38, i.e., the outer surface side, has a convex shape. In this example, such a protrusion insertion portion 38 is configured as a bottomed cylindrical shape (a bottomed cone shape in the illustrated example).

The other second cover plate portion 30b has a "other-side engaging portion 39" at the axial center of the tip of the curved portion 33b. The other-side engaging portion 39 is positioned to protrude radially outward from the curved portion 33b. The other-side engaging portion 39 has a through hole 40 through which the snap-fit piece 37 can be inserted.

The engaging portion 36 on one side and the engaging portion 39 on the other side are mutually reciprocal. To engage the engaging portion 36 and the engaging portion 39, the snap-fit piece 37 of the engaging portion 36 is inserted through the through-hole 40 of the engaging portion 39, and the claws on the tip of the snap-fit piece 37 protruding from the through-hole 40 are engaged with the opening periphery of the through-hole 40. To disengage the engaging portion 36 and the engaging portion 39, the claws of the snap-fit piece 37 are disengaged from the opening periphery of the through-hole 40, and the snap-fit piece 37 is removed from the through-hole 40.

The yoke cover 1 in this example further comprises a pair of stopper portions 41. The pair of stopper portions 41 are connected to the axial ends of the first cover plate portion 29. More specifically, the pair of stopper portions 41 are flat plates that are bent at a right angle from the axial ends of the first cover plate portion 29 toward the inner surface (upper surface in Figures 8 and 9(b)) of the first cover plate portion 29, which is radially inward in the closed state (see Figure 7). When implementing the present invention, any shape can be adopted for each of the stopper portions constituting the pair. When implementing the present invention, at least one of the pair of stopper portions can be omitted.

The yoke cover 1 in this example further includes a slit entry portion 42. The slit entry portion 42 is connected to the first cover plate portion 29. More specifically, the slit entry portion 42 is connected to the center of the inner surface of the first cover plate portion 29 in the width direction. The slit entry portion 42 is configured as a flat plate extending in the axial direction and in the direction normal to the inner surface. Both axial ends of the slit entry portion 42 are connected to the center of a pair of stopper portions 41 in the width direction. The slit entry portion 42 has a notched bolt engagement portion 43 in its axial middle section, opening towards the tip side which is radially inward in the closed state (see Figure 7). The slit entry portion can be omitted when implementing the present invention.

In this example of the yoke cover 1, by swinging a pair of second cover plate portions 30a and 30b relative to the first cover plate portion 29, it is possible to move the tip of one second cover plate portion 30a and the tip of the other second cover plate portion 30b toward and away from each other.

As shown in Figures 8 through 7, the yoke cover 1 can be closed by swinging a pair of second cover plate portions 30a and 30b toward each other, causing the ends of the pair of second cover plate portions 30a and 30b to abut against each other, and engaging one-sided engaging portion 36 with the other-sided engaging portion 39. This connects the first cover plate portion 29, one second cover plate portion 30a, and the other second cover plate portion 30b in a cylindrical shape, creating a closed state in which an arrangement space S is formed radially inward.

As shown in Figures 7 to 8, the yoke cover 1 can be opened by disengaging the engagement between one-sided engagement portion 36 and the other-sided engagement portion 39, thereby causing the pair of second cover plate portions 30a and 30b to swing in a direction where their ends move away from each other, thus opening the arrangement space S.

When implementing the present invention, any structure can be adopted as the structure for removably engaging the tip portions of a pair of second cover plates.

In this example, when closed, the axial end of the yoke cover 1 does not have a sharp corner around its entire circumference when viewed from the axial side.

Specifically, in the closed state, the axial end of the yoke cover 1 has corners on both the left and right ends of the lower end, as viewed from the axial side, i.e., in Figure 6(b). However, these corners are not sharp and have a large radius of curvature (R-shape). The radius of curvature of this R-shape is preferably 1.0 mm or more, and more preferably 2.5 mm or more.

At the axial end of the yoke cover 1 in the closed state, the following connections are provided: the connection between the outer surface of one second cover plate portion 30a and the axial side of the flange portion 34a; the connection between the outer surface of the other second cover plate portion 30b and the axial side of the flange portion 34b; and the connection between the outer surface of the first cover plate portion 29 and the axial side of the stopper portion 41. Each of these connections is provided with an R-shaped chamfer. The radius of curvature of the R-shape is preferably 1.0 mm or more, and more preferably 2.5 mm or more.

In this example, the front end of the steering shaft 4 can be connected to the yoke 13 using bolts 23, and then the yoke cover 1 can be assembled to the yoke 13.

When assembling the yoke cover 1 to the yoke 13, first, with the yoke cover 1 in the open state (see Figures 8 to 9(b)), the slit entry portion 42 is inserted into the slit 19, and the intermediate portion of the shaft portion 24 of the bolt 23 is engaged with the bolt engagement portion 43 of the slit entry portion 42. Simultaneously, a pair of stopper portions 41 are positioned to sandwich the pair of protruding portions 21a and 21b, which constitute the pair of yoke flange portions 20a and 20b, from both axial sides. Then, the first cover plate portion 29 covers the radially outer surface (lower surface in Figures 6(a) and 6(b)) of the pair of yoke flange portions 20a and 20b on the outer circumferential surface of the other axial side portion of the yoke base portion 14. The slit entry portion 42 does not protrude radially inward from the inner circumferential surface 18 of the yoke base portion 14.

In this example, in this state, the yoke cover 1 is positioned axially relative to the yoke 13 based on the engagement of the bolt engagement portion 43 of the slit entry portion 42 with the shaft portion 24 of the bolt 23, and/or the axial engagement of the pair of stopper portions 41 and the pair of protruding portions 21a and 21b. Furthermore, the first cover plate portion 29 is positioned radially relative to the yoke 13 based on the contact of the inner surface of the first cover plate portion 29, and/or the tip of one of the pair of stopper portions 41 on the axial side, with the radially outer surfaces of the pair of yoke flange portions 20a and 20b.

Next, by swinging the pair of second cover plate portions 30a and 30b toward each other, the head 25 of the bolt 23 is inserted into the concave portion of the head insertion portion 35, and the convex portion 28 is inserted into the concave portion of the convex portion insertion portion 38. Simultaneously, the tips of the pair of second cover plate portions 30a and 30b are brought together, and the engagement portion 36 on one side and the engagement portion 39 on the other side are engaged, thereby closing the yoke cover 1. As a result, as shown in Figures 2 to 6(b), the axial other side portion of the yoke base 14 (including the axial other side end face 31) is positioned within the arrangement space S of the yoke cover 1.

In this example, in the closed state, the pair of second cover plates 30a and 30b cover the remaining circumferential portion of the outer circumferential surface of the other axial side portion of the yoke base 14 (i.e., the circumferential portion that is not covered by the radially outer surface of the pair of yoke flange portions 20a and 20b covered by the first cover plate 29). Specifically, they cover the widthwise outer surface of the pair of yoke flange portions 20a and 20b, and the portion that is not covered by the pair of yoke flange portions 20a and 20b in the circumferential direction.

In other words, one second cover plate portion 30a covers the remaining circumferential portion of the outer surface of the other axial side of the yoke base portion 14, specifically the half on the head 25 side with respect to the axial direction of the bolt 23 (the portion to the left of the dashed line α in Figure 6(a), and the portion to the right of the dashed line α in Figure 6(b)). Specifically, the straight portion 32a of one second cover plate portion 30a covers the flat surface portion of the aforementioned half, which is the outer surface in the width direction of one yoke flange portion 20a. The curved portion 33a of one second cover plate portion 30a covers the cylindrical convex surface portion of the aforementioned half, which is located further from the slit 19 than the flat surface portion in the circumferential direction. Furthermore, the head insertion portion 35 covers the head 25.

In contrast, the other second cover plate portion 30b covers the remaining circumferential portion of the outer surface of the axially opposite portion of the yoke base portion 14, specifically the half opposite to the head 25 with respect to the axial direction of the bolt 23 (the portion to the right of the dashed line α in Figure 6(a), and the portion to the left of the dashed line α in Figure 6(b)). Specifically, the straight portion 32b of the other second cover plate portion 30b covers the flat surface portion of the aforementioned half, which is the outer surface in the width direction of the other yoke flange portion 20b. The curved portion 33b of the other second cover plate portion 30b covers the cylindrical convex surface portion of the aforementioned half, which is located further from the slit 19 than the flat surface portion in the circumferential direction. Furthermore, the convex insertion portion 38 covers the convex portion 28.

In this example, in the closed state, the tips of the flange portions 34a and 34b, located at one axial end of the pair of second cover plate portions 30a and 30b, abut against the cylindrical convex surface on the outer circumferential surface of the yoke base portion 14. Based on this, the pair of second cover plate portions 30a and 30b are positioned radially relative to the yoke 13.

In other words, in this example, when closed, the yoke cover 1 is fitted onto the axial side of the yoke base 14 without any looseness.

In this example, the first cover plate portion 29 and the pair of second cover plate portions 30a and 30b each have a shape that, when closed, aligns circumferentially with respect to the outer peripheral surface of the other axial portion of the yoke base portion 14, as shown in Figures 6(a) and 6(b).

To remove the yoke cover 1 from the yoke 13, the engagement between one-sided engagement portion 36 and the other-sided engagement portion 39 is disengaged, causing the pair of second cover plate portions 30a and 30b to swing away from each other. This opens the yoke cover 1, allowing it to be removed from the yoke 13.

When implementing the present invention, in the closed state of the yoke cover, the circumferential portion of the outer surface of the axially opposite side of the yoke base that each of the first cover plate portion and the pair of second cover plate portions covers can be arbitrarily determined. For example, when implementing the present invention, the portion of the outer surface of the axially opposite side of the yoke base that is circumferentially separated from the pair of yoke flange portions can be covered by the first cover plate portion, while the remaining circumferential portion of the outer surface—the widthwise outer surface of the pair of yoke flange portions and the radially outer surface of the pair of yoke flange portions—can be covered by the pair of second cover plate portions.

According to the yoke cover 1 in this example, the corner portion 44 (see Figures 4 to 6) located on the peripheral edge of the end face 31 on the other axial side of the yoke base 14 that constitutes the yoke 13 can be prevented from coming into contact with a person's hands or feet.

In other words, in the manufacturing of the yoke 13, the end face 31 is finished by machining, so the corners 44 on the periphery of the end face 31 become sharp. Therefore, it is desirable to prevent such corners 44 from coming into contact with people's hands or feet. In this example, with the yoke cover 1 attached to the yoke 13, the axially opposite portion of the yoke base 14 (including the axially opposite end face 31) is positioned within the arrangement space S located radially inside the yoke cover 1. Therefore, the corners 44 on the periphery of the axially opposite end face 31 of the yoke base 14 are not exposed to the outside of the yoke cover 1. Thus, it is possible to prevent the corners 44 from coming into contact with people's hands or feet. Specifically, it is possible to prevent the corners 44 from coming into contact with the driver's feet or with people's hands during cleaning of the vehicle interior.

In this example, when the yoke cover 1 is attached to the yoke 13 in the closed position, the axial end of the yoke cover 1 does not have a sharp corner. Therefore, safety can be ensured in case the driver's foot or other body part comes into contact with the axial end of the yoke cover 1.

The yoke cover 1 in this example includes a head insertion portion 35 that covers the head 25 of the bolt 23. This prevents the driver's foot or other body parts from coming into contact with the bolt head 25.

The yoke cover 1 in this example includes a protrusion insertion portion 38 that covers the protrusion 28. Therefore, it is possible to prevent the driver's foot or other body parts from coming into contact with the protrusion 28. When implementing the present invention, a cylindrical protrusion insertion portion without a bottom, or a protrusion insertion portion configured as a through-hole penetrating the other second cover plate portion, can also be used.

In this example, with the yoke cover 1 attached to the yoke 13, the yoke cover 1 covers the radially outer opening of the slit 19 in the yoke 13. Therefore, it is possible to prevent the driver's feet or other body parts from touching the radially outer opening edge of the slit 19. That is, in the manufacturing of the yoke 13, the slit 19 is finished by machining, resulting in a sharp corner on the radially outer opening edge of the slit 19. The yoke cover 1 in this example prevents the driver's feet or other body parts from touching such a corner.

The structure of this example includes engagement points between the head 25 and the head insertion portion 35 of the bolt 23, engagement points between the protrusion 28 and the protrusion insertion portion 38, engagement points between a pair of protruding portions 21a and 21b and a pair of stopper portions 41, and engagement points between the intermediate portion of the shaft portion 24 of the bolt 23 and the bolt engagement portion 43 of the slit entry portion 42. Based on each of these engagement points, axial movement of the yoke cover 1 relative to the yoke 13 can be prevented.

In this example, the first cover plate portion 29 and the pair of second cover plate portions 30a and 30b each have a shape that, in the closed state, circumferentially aligns with the outer circumferential surface of the other axial portion of the yoke base portion 14. Therefore, the yoke cover 1 can be made compact in the closed state.

[Example 2]
A second example of an embodiment of the present invention will be described with reference to Figure 10.

In this example, the head insertion portion 35a constituting the yoke cover 1a is configured in a conical or cylindrical shape. Because the head insertion portion 35a is positioned around the head 25 of the bolt 23, it effectively prevents the driver's foot or other body parts from hitting the head 25.

In this example, even after the yoke cover 1a is assembled to the yoke 13, the head 25 of the bolt 23 can be visually inspected from outside the yoke cover 1a through the opening of the head insertion portion 35a. Therefore, during pre-shipment inspections of vehicles, it is possible to visually check from outside the yoke cover 1a whether any bolts 23 have been forgotten during assembly. Other configurations and effects are the same as in the first example.

[Example 3]
A third embodiment of the present invention will be described with reference to Figure 11.

In this example, the head insertion portion 35b of the yoke cover 1b is formed by a through-hole that penetrates one of the second cover plate portions 30a. In this example, with the yoke cover 1b assembled to the yoke 13, the head 25 of the bolt 23 protrudes to the outside of the yoke cover 1b through the head insertion portion 35b. Therefore, during pre-shipment inspections of vehicles, it is possible to visually check from the outside of the yoke cover 1a whether any bolts 23 have been left installed.

Furthermore, in this example, since the head 25 of the bolt 23 protrudes outside the yoke cover 1b through the head insertion portion 35b, the front end of the steering shaft can be connected to the yoke 13 using the bolt 23 after the yoke cover 1b has been assembled to the yoke 13. Other configurations and effects are the same as in the first example.

1, 1a, 1b Yoke cover 2 Steering device 3 Steering wheel 4 Steering shaft 5 Steering column 6a, 6b Universal joint 7 Intermediate shaft 8 Steering gear unit 9 Pinion shaft 10 Rack 11 Tie rod 12 Steering wheel 13 Yoke 14 Yoke base 15 Yoke arm 16 Circular hole 17 Outer surface 18 Inner surface 19 Slit 20a, 20b Yoke flange 21a, 21b Protruding part 22a, 22b Bolt hole 23 Bolt 24 Shaft part 25 Head 26 Boss part 27 Bolt engagement part 28 Protrusion 29 First cover plate part 30a, 30b Second cover plate part 31 End face 32a, 32b Straight part 33a, 33b Curved part 34a, 34b Flange portion 35, 35a, 35b Head insertion portion 36 One-side engaging portion 37 Snap-fit piece 38 Protrusion insertion portion 39 Other-side engaging portion 40 Through hole 41 Stopper portion 42 Slit entry portion 43 Bolt engaging portion 44 Corner portion

Claims (10)

A yoke cover for a universal joint, comprising 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 opening at one circumferential location on both radial sides and the other axial side, a pair of yoke flanges facing each other across the slit on the other axial side portion, and a pair of bolt holes passing through the pair of yoke flanges, the shafts of bolts being inserted through or screwed into the pair of bolt holes, and the heads of the bolts abutting against the widthwise outer surface of one of the pair of yoke flanges, which is part of the outer circumferential surface of the other axial side portion of the yoke base,
The device comprises a first cover plate portion and a pair of second cover plate portions, the base ends of which are pivotably connected to the ends on both sides in the width direction of the first cover plate portion, and the tip portions of which can be moved toward and away from each other based on the pivoting motion.
By bringing the tips of the pair of second cover plate portions closer together and engaging them, the first cover plate portion and the pair of second cover plate portions are connected in a cylindrical shape to form a cylindrical body, creating a closed state in which an arrangement space is formed radially inward, and an open state in which the tips of the pair of second cover plate portions are moved apart from each other to open the arrangement space.
In the closed state, the other axial portion of the yoke base is positioned within the arrangement space.
Yoke cover. In the closed state, the first cover plate covers the circumferential portion of the outer circumferential surface of the other axial side portion of the yoke base located between the openings of the pair of bolt holes, and the pair of second cover plate portions covers the remaining circumferential portion of the outer circumferential surface, as described in claim 1. The yoke cover according to claim 2, wherein the circumferential portion of the outer circumferential surface of the other axial portion of the yoke base, located between the openings of the pair of bolt holes, is the radially outer surface of the pair of yoke flange portions. At least one of the ends on both sides of the axial direction of the first cover plate portion is provided with a stopper portion connected to that end,
In the closed state, the stopper portion engages axially with a pair of protruding portions of the pair of yoke flange portions that extend radially outward from one axial side portion of the yoke base.
The yoke cover according to claim 3. It is connected to the first cover plate portion and includes a slit entry portion that enters the slit in the closed state,
The slit entry portion opens radially inward from the yoke base and has a notched bolt engagement portion that engages with the shaft portion.
The yoke cover according to claim 3. The yoke cover according to claim 2, wherein, of the pair of second cover plate portions, the second cover plate portion positioned on the head side with respect to the axial direction of the bolt has a head insertion portion into which the head is inserted. The yoke cover according to claim 6, wherein the inner side in the width direction of the head insertion portion in the closed state has a concave shape into which the head is inserted, and the outer side in the width direction of the head insertion portion in the closed state has a convex shape. The yoke cover according to claim 2, wherein the second cover plate portion of the pair of second cover plate portions, which is positioned on the opposite side of the bolt head with respect to the axial direction of the bolt, has a protrusion insertion portion into which a protrusion is inserted. This protrusion is formed by a boss portion and/or the tip of the shaft portion protruding from the bolt hole on the outer surface in the width direction of the other yoke flange portion of the pair of yoke flange portions, which is a part of the outer surface of the other yoke flange portion of the pair of yoke flange portions, or by the tip of the shaft portion and a nut that is screwed onto the tip and contacts the outer surface in the width direction of the other yoke flange portion. The yoke cover according to claim 8, wherein the inner side in the width direction of the protrusion insertion portion in the closed state has a concave shape into which the protrusion is inserted, and the outer side in the width direction of the protrusion insertion portion in the closed state has a convex shape. The yoke cover according to any one of claims 1 to 9, wherein each of the first cover plate portion and the pair of second cover plate portions has a shape that, in the closed state, is aligned circumferentially with respect to the outer peripheral surface of the other axial portion of the yoke base portion.