Steering column

A steering column includes: a cylindrical member that holds a steering shaft in such a manner as to allow extension and contraction of the steering shaft; a holding member that holds the cylindrical member; a fixture member that is fixed to a vehicle body; a coupling member that couples the fixture member and the holding member; and an energy absorbing member that is partially fixed to the holding member. The coupling member uncouples the fixture member and the holding member when the holding member moves forward for a specified distance in an axial direction. The fixture member has an engaging section arranged at a position where the engaging section is engaged with an engaged section of the energy absorbing member when the holding member moves forward for the specified distance or longer in the axial direction.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2018-098472 filed on May 23, 2018 including the specification, drawings and abstract is incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

The disclosure relates to a steering column.

2. Description of Related Art

A mechanism that absorbs impact on a driver during a secondary collision, in which the driver collides with a steering wheel due to a collision of a vehicle, is requested for a steering column. For example, in Japanese Patent Application Publication No. 2015-9685 (JP 2015-9685 A), a steering device including an absorbing member that absorbs impact energy during the secondary collision is disclosed. This steering device includes an upper bracket, an engaging section that integrally moves with the upper bracket, a fixture section, and the absorbing member. The fixture section is fixed to a vehicle body by a bolt, and thus relative positions thereof in the vehicle body before and after the secondary collision is fixed. The absorbing member includes: a fixed section that is fixed to the fixture section; an engaged section that opposes the engaging section; a coupling section that couples the fixed section and the engaged section; and an idle section. The idle section causes the engaged section to be disposed in such a manner as to keep a specified idle distance from the engaging section. During the secondary collision, the upper bracket moves in a specified moving direction. The absorbing member absorbs the energy in the secondary collision when the coupling section is deformed by engagement of the engaging section and the engaged section.

SUMMARY

In the steering device described above, the upper bracket in a separable state from the fixture section (a capsule) is fastened with the capsule to the vehicle body by the bolt. The capsule and the upper bracket are further coupled to each other by a resin pin. In such a structure, the upper bracket moves when the secondary collision occurs. Consequently, the resin pin is ruptured, and the upper bracket separates from the capsule. Then, the engaging section of the moving upper bracket is engaged with the absorbing member. In this way, the absorbing member absorbs the impact energy generated by the secondary collision.

However, as in the structure described above, in a structure in which a member (a moving member), which is unfixed from the vehicle body and moves by the impact during the secondary collision, is engaged with the absorbing member, engaged portions of the moving member and the absorbing member move with respect to the vehicle body. For such a reason, it is difficult to secure a stable engaged state between the moving member and the absorbing member during the secondary collision, for example.

The disclosure provides a steering column capable of performing appropriate impact absorbing operation with a simple configuration.

A steering column according to one aspect of the disclosure is a steering column provided in a vehicle body. The steering column includes a cylindrical member, a holding member, a fixture member, a coupling member, and an energy absorbing member. The cylindrical member holds a steering shaft in such a manner as to allow extension and contraction of the steering shaft to the front in an axial direction. The holding member holds the cylindrical member. The fixture member is fixed to the vehicle body. The coupling member is configured to couple the fixture member and the holding member. The coupling member is configured to uncouple the fixture member and the holding member when the holding member moves forward for a specified distance in the axial direction. The energy absorbing member is partially fixed to the holding member. The fixture member has an engaging section arranged at a position where the engaging section is engaged with the engaged section of the energy absorbing member in the case where the holding member moves forward for the specified distance or longer in the axial direction during a secondary collision.

In the steering column, the engaging section may be provided in such a manner as to be projected from the fixture member. The engaged section may be an opening provided in the energy absorbing member. The engaging section may be arranged in such a manner as to extend through the opening. The opening may be in such size that a clearance is provided between the opening and a rear side of the engaging section in the axial direction. On a portion of the engaging section that is exposed from the opening, a head that has a larger portion than the opening when seen in a projected direction of the engaging section may be provided, and the head may be arranged separately from a peripheral edge of the opening in the projected direction.

In the steering column, the head may be a head of a bolt that fixes the fixture member to the vehicle body by fastening the fixture member and the vehicle body. The engaging section may have a through hole that causes a shaft section of the bolt to extend through the engaging section in the projected direction. The energy absorbing member may have a plate shape. A projection length of the engaging section from the fixture member may be greater than a thickness of the peripheral edge of the opening in the energy absorbing member.

In the steering column, the engaging section may include a circular tube member. The circular tube member may be provided in an attachment hole provided in the fixture member such that a part of the circular tube member in a tube axial direction is projected from the fixture member. The shaft section of the bolt may be arranged to extend through the circular tube member in the tube axial direction.

In the steering column, the engaging section may be a step of a stepped bolt that fixes the fixture member to the vehicle body by fastening the fixture member and the vehicle body. The head may be a head of the stepped bolt. The energy absorbing member may have a plate shape. A thickness of the step in an axial direction of the stepped bolt may be greater than a thickness of the peripheral edge of the opening in the energy absorbing member.

In the steering column, a convex section that is projected toward the head or the fixture member may be formed on the peripheral edge of the opening in the energy absorbing member.

In the steering column, the energy absorbing member may include an annular section having the opening. The annular section may have a curved or bent shape to be projected toward the head or the fixture member.

The steering column described above can perform appropriate impact absorbing operation with a simple configuration.

DETAILED DESCRIPTION OF EMBODIMENTS

A specific description will hereinafter be made on an embodiment and modified embodiments thereof with reference to the drawings. Note that the embodiment and the modified embodiments, which will be described below, each illustrate a comprehensive or specific example. Numerical values, shapes, materials, constituent elements, arranged positions and coupled states of the constituent elements, steps, orders of steps described in the embodiment and the modified embodiments below are merely examples and thus have no intention to limit the invention. In addition, of the constituent elements described in the embodiment and the modified embodiments below, the constituent elements that are not described in the independent claim having the highest concept will be described as optional constituent elements.

Each of the drawings is a schematic view in which the constituent elements are appropriately exaggerated, omitted, or adjusted for a ratio to illustrate the disclosure, and thus shapes, positional relationships, and the ratios of the constituent elements shown in the drawings may differ from the actual shapes, the actual positional relationships, and the actual ratios thereof. Furthermore, there is a case where expressions indicating relative directions and postures, such as parallel and orthogonal, are used in the embodiment and the claims described below. However, each of such expressions also includes the relative direction or the posture not strictly corresponding to the relative direction or the posture indicated by the expression. For example, an expression that two directions are parallel to each other not only means that the two directions are completely parallel to each other but also means that the two directions are substantially parallel to each other, that is, a few percent of a difference is also included, for example.

Embodiment

A description will first be made on an overall configuration of a steering column10according to the embodiment with reference toFIG. 1andFIG. 2.FIG. 1is a perspective view of external appearance of the steering column10according to the embodiment.FIG. 2is an exploded perspective view of the steering column10according to the embodiment.

InFIG. 1, an approximate shape and an approximate arranged position of a steering shaft15are indicated by dotted lines. InFIG. 2, the steering shaft15is not shown. A one-dot chain line inFIG. 1represents a rotation axis A (a virtual axis) of the steering shaft15. In this embodiment, the rotation axis A is parallel to a Z-axis. Hereinafter, when an “axial direction” is simply described, the “axial direction” means a parallel direction with the rotation axis A (a Z-axis direction in this embodiment). In addition, “forward direction in the axial direction” means a direction that is parallel to the rotation axis A and is extending toward a front side of a vehicle (a positive side of the Z-axis). “Rearward direction in the axial direction” means a direction that is parallel to the rotation axis A and is extending toward a rear side of the vehicle (a negative side of the Z-axis).

The steering column10according to this embodiment is a device mounted on the vehicle such as an automobile, and is a device holding the steering shaft15that rotates when an unillustrated steering wheel is operated. The steering column10holds the steering shaft15such that an axial length and a vertical tilt of the steering shaft15can be adjusted by a driver's operation, for example. That is, with the steering column10, a position and a posture of the steering wheel can be adjusted (hereinafter simply referred to as “position adjustment”).

The steering shaft15includes, for example, an upper shaft and a lower shaft. The upper shaft is disposed rearward direction (on the steering wheel side) of the lower shaft. The upper shaft and the lower shaft are spline-fitted to each other. When the upper shaft slides in the axial direction with respect to the lower shaft, the steering shaft15is stretched or contracted in the axial direction. That is, the steering shaft15has a telescopic structure.

The steering column10, which has the steering shaft15just as described, specifically includes: a cylindrical member20that holds the steering shaft15in such a manner as to allow the steering shaft15to be stretched or contracted; a holding member30that holds the cylindrical member20; and a fixture member40that is fixed to a vehicle body. The fixture member40and the holding member30are coupled to each other by a coupling member60.

In this embodiment, the cylindrical member20has an outer tube21and an inner tube22. The holding member30has a holding bracket31on the cylindrical member20side and a fixture bracket32on the vehicle body side.

Each of the outer tube21and the inner tube22is a tube that is made of metal and extends in the axial direction. In this embodiment, the outer tube21is disposed rearward direction of the inner tube22. That is, the outer tube21is an upper tube, and the inner tube22is a lower tube.

The outer tube21is a member that fixes the upper shaft of the steering shaft15in the axial direction and supports the upper shaft of the steering shaft15in such a manner as to allow rotation thereof. The inner tube22is a member that fixes the lower shaft of the steering shaft15in the axial direction and supports the lower shaft of the steering shaft15in such a manner as to allow rotation thereof. The outer tube21is attached to the inner tube22in a movable manner in the axial direction. That is, when the outer tube21moves in the axial direction with respect to the inner tube22, the upper shaft of the steering shaft15moves in the axial direction with respect to the lower shaft. In this way, the entire steering shaft15is stretched or contracted in the axial direction.

The holding bracket31is fixed to the outer tube21by welding, for example. The holding bracket31is attached in such a manner as to be able to move and change a posture thereof with respect to the fixture bracket32on the vehicle body side.

More specifically, as shown inFIG. 2, when a tip of a bolt61, which extends through an elongated hole31aof the holding bracket31and an elongated hole35of the fixture bracket32in a lateral direction (an X-axis direction), is screwed to a nut62, the fixture bracket32is attached to the holding bracket31. In addition, a lever or a rotation cam, which is not shown, is arranged on a head side of the bolt61. For example, when the lever in a lowered state is raised, the fixture bracket32is brought into a state of tightening the holding bracket31in the lateral direction. That is, the holding bracket31is brought into a state where a position thereof is fixed (a locked state). Furthermore, when the lever is lowered in the locked state of the holding bracket31, the fixture bracket32untightens the holding bracket31. As a result, the holding bracket31can move. More specifically, the elongated hole31aof the holding bracket31is elongated in the axial direction. Thus, the holding bracket31can move in the axial direction. More specifically, the outer tube21can move with the holding bracket31in the axial direction. In this way, the steering shaft15is stretched or contracted. That is, a longitudinal position of the steering wheel, which is attached to a rear end of the steering shaft15in the axial direction, is changed (so-called “telescopic adjustment”).

The elongated hole35of the fixture bracket32is elongated in the vertical direction. Thus, a vertical tilt (a tilt in a Y-Z plane) of the holding bracket31can be changed. More specifically, a tilt of the cylindrical member20is changed along with the holding bracket31, and thus the tilt of the steering shaft15is also changed. As a result, an angle and a vertical position of the steering wheel, which is attached to a rear end of the steering shaft15in the axial direction, are changed (so-called “tilt adjustment”).

As described above, the steering column10according to this embodiment is a device capable of adjusting the vertical (tilt) position and the longitudinal (telescopic) position of the steering wheel.

The steering column10including a mechanism, which performs tilt and telescopic position adjustment of the steering wheel as described above, is fixed to the vehicle body via the fixture member40. As shown inFIG. 2, the fixture member40is a member that is made of the metal and has a through hole41through which a shaft section71of a bolt70passes. The bolt70that is inserted through the through hole41penetrates a part of the vehicle body and is screwed to a nut. In this way, the fixture member40is fixed to the vehicle body.

In addition, as shown inFIG. 1andFIG. 2, the fixture member40is attached to the fixture bracket32and is coupled to the fixture bracket32by the coupling members60. Each of the coupling members60is a pin that is made of a resin (a resin pin), for example. Each of the coupling members60is arranged in a state of penetrating a pin hole42and a pin hole33that are aligned vertically and respectively provided in the fixture member40and the fixture bracket32. In this embodiment, the steering column10has a right and left pair of the fixture members40, and each of the two fixture members40is coupled to the fixture bracket32by the three coupling members60. That is, in this embodiment, the two fixture members40are coupled to the fixture bracket32by a total of the six coupling members60. Each of these six coupling members60has strength that can endure a load generated by a normal operation for the steering column10, such as the position adjustment of the steering wheel.

When a secondary collision occurs, these six coupling members60uncouple the fixture bracket32(the holding member30) from the fixture members40by impact energy. As a result, the holding member30moves forward in the axial direction without being restrained by the fixture members40. During such movement, an energy absorbing member50, which moves with the holding member30, is engaged with the fixture member40, and the energy absorbing member50is deformed in conjunction with the movement of the holding member30. In this way, the impact energy is absorbed. That is, the steering column10performs impact absorbing operation during the secondary collision by uncoupling using the coupling members60(shearing of the coupling members60in this embodiment) and the deformation of the energy absorbing member50.

A description will hereinafter be made on a configuration of the steering column10related to the impact absorbing operation, and the like with reference toFIG. 1andFIG. 2, which have been referred above, andFIG. 3toFIG. 8.

FIG. 3is a perspective view of external appearance of the energy absorbing member50according to the embodiment.FIG. 4is a perspective view of external appearance of the fixture member40according to the embodiment. More specifically,FIG. 3is a perspective view at the time when the energy absorbing member50is seen obliquely downward.FIG. 4is a perspective view at the time when the fixture member40is seen obliquely upward.FIG. 5is a cross-sectional view of a structure of the fixture member40according to the embodiment and a periphery thereof. More specifically,FIG. 5shows a cross section, which is taken along line V-V inFIG. 1, in the Y-Z plane.

The energy absorbing member50according to this embodiment is a member that is made of the metal, and, as shown inFIG. 3, has: an annular section52having an opening51; and a fixed section53as a portion that is fixed to the holding member30. In this embodiment, the fixed section53is fixed to the fixture bracket32provided in the holding member30by welding, for example. A slit55aand a thin section55bare provided between the annular section52and the fixed section53.

The fixture member40according to this embodiment is the member that is made of the metal as described above, and, as shown inFIG. 4andFIG. 5, has the through hole41through which the shaft section71of the bolt70passes. The fixture member40is also provided with an engaging section45, which is engaged with the energy absorbing member50, on a surface thereof on a head72side of the bolt70(a surface on a negative side of the Y-axis).

In this embodiment, as shown inFIG. 4andFIG. 5, the engaging section45is provided in a projected manner from the fixture member40, and, as shown inFIG. 5, is arranged in a state of penetrating the opening51of the energy absorbing member50. That is, in this embodiment, the opening51of the energy absorbing member50is an example of the engaged section that is engaged with the engaging section45of the fixture member40.

The fixture member40is provided with a slide groove43in which the fixture bracket32is partially inserted. As shown inFIG. 1andFIG. 2, by using the slide groove43, the fixture member40is attached to the fixture bracket32. Furthermore, the fixture member40and the fixture bracket32are coupled to each other by the three coupling members60. More specifically, as shown inFIG. 5, each of the coupling members60is arranged in a state of penetrating a part of the fixture member40and a part of the fixture bracket32.

When the secondary collision occurs, an external force in a direction to separate the annular section52, which has the opening51engaged with the engaging section45, and the fixed section53, which is fixed to the fixture bracket32, from each other is applied to the energy absorbing member50. As a result, the thin section55bof the energy absorbing member50is ruptured and deformed to open a first portion56abetween the slit55aand the thin section55band a second portion56bon an outer side of each of the slit55aand the thin section55boutward. Just as described, when the energy absorbing member50is deformed, the energy absorbing member50absorbs the impact energy during the secondary collision.

In this embodiment, the head72, which has a larger portion than the opening51at the time when seen from a projected direction (a positive Y-axis direction) of the engaging section45, is arranged on a portion of the engaging section45that is exposed from the opening51. Since such a head72is stuck by a peripheral edge of the opening51, disengagement of the opening51from the engaging section45is prevented.

In this embodiment, the through hole41is provided in the engaging section45. That is, the engaging section45has the through hole41that causes the shaft section71of the bolt70to extend through the engaging section45in the projected direction of the engaging section45. Accordingly, the head72of the bolt70has a function of preventing the disengagement of the opening51from the engaging section45.

In addition, in the projected direction of the engaging section45, the head72is separately arranged from the peripheral edge of the opening51in the energy absorbing member50. That is, in the case where the fixture member40is fixed to the vehicle body by the bolt70, the head72of the bolt70is in a state of not pressing the peripheral edge of the opening51. Furthermore, as shown inFIG. 5, the opening51of the energy absorbing member50is provided in such size that a clearance having a distance D (hereinafter referred to as a “clearance D”) at the rear of the engaging section45in the axial direction (in the negative Z-axis direction). That is, the opening51is in such size that the clearance D is provided between the opening51and the rear side of the engaging section45, which is arranged to extend through the opening51, in the axial direction. Accordingly, after moving forward in the axial direction (the positive Z-axis direction) for a distance corresponding to the clearance D, the opening51of the energy absorbing member50is engaged with the engaging section45.

As described above, the bolt70, which fastens the fixture member40to the vehicle body in the state of penetrating the energy absorbing member50, fixes the fixture member40to the vehicle body in a state of not pressing the energy absorbing member50in an axial direction of the bolt70(a parallel direction to the Y-axis direction and hereinafter referred to as a “bolt-axis direction”). Furthermore, the opening51of the energy absorbing member50is provided such that the opening51is engaged with the engaging section45after moving forward in the axial direction (the positive Z-axis direction) for the specified distance with respect to the fixture member40fixed to the vehicle body.

A description will now be made on details of the impact absorbing operation realized by the fixture member40, the holding member30(the fixture bracket32), and the energy absorbing member50with reference toFIG. 6toFIG. 8.

FIG. 6is a view of the structure of the fixture member40and the periphery thereof during a normal time.FIG. 7is a view of the structure of the fixture member40and the periphery thereof immediately after the secondary collision.FIG. 8is a view of the structure of the fixture member40and the periphery thereof after the energy absorbing member50starts being deformed.

Note that each ofFIG. 6toFIG. 8shows the structure of the fixture member40and the periphery thereof in a simple cross section, and a position of the cross section is the same as the position of the cross section shown inFIG. 5. In addition, each ofFIG. 6toFIG. 8only shows constituent elements of the fixture member40and constituent elements related to the fixture member40, and thus the other constituent elements are not shown. These supplementary notes onFIG. 6toFIG. 8are also applied toFIG. 9andFIG. 10, which will be described below.

As shown inFIG. 6, in the steering column10according to the embodiment, the shaft section71of the bolt70, which fixes the fixture member40to a vehicle body120, is arranged in the state of penetrating the through hole41of the fixture member40and the opening51of the energy absorbing member50. Note that the vehicle body120is a part of a frame of the automobile on which the steering column10is mounted, for example. The through hole41, through which the shaft section71passes, is provided in the engaging section45, which is provided in the projected manner from the fixture member40, and a projection length of the engaging section45is greater than a thickness of the peripheral edge of the opening51(the annular section52) in the energy absorbing member50. Accordingly, the head72of the bolt70is in the state of pressing the engaging section45in the bolt-axis direction and separating from the peripheral edge of the opening51(the annular section52) in the energy absorbing member50. That is, a clearance having a distance G (hereinafter referred to as a “clearance G”) is provided between the head72of the bolt70and the annular section52. In addition, the opening51, in which the engaging section45is arranged in a penetrating manner, has such size that the clearance D is provided between the opening51and the engaging section45, and the clearance D is located at the rear of the engaging section45in the axial direction.

When the secondary collision occurs in the above state, the outer tube21(seeFIG. 1andFIG. 2) is pressed forward in the axial direction. As a result, the holding member30(the holding bracket31and the fixture bracket32) attempts to move forward in the axial direction. At this time, the coupling member60, which is the resin pin and couples the fixture member40and the fixture bracket32, starts being sheared. In addition, at initiation of shearing of the coupling member60, the clearance D exists at the rear of the engaging section45in the axial direction. Thus, the opening51moves forward in the axial direction without being engaged with the engaging section45. Furthermore, since the distance G exists between the head72of the bolt70and the peripheral edge of the opening51, the annular section52having the opening51moves forward in the axial direction without receiving a fastening force by the bolt70. That is, the opening51moves for the specified distance D without substantially receiving resistance from any of the other elements, and is then engaged with the engaging section45as shown inFIG. 7.

More specifically, after a shearing load on the coupling member60exceeds a peak, the opening51is engaged with the engaging section45. That is, a value of the specified distance D, and a shape, size, a material, and the like of the coupling member60are determined in such a manner as to satisfy such a condition. Accordingly, when the holding member30moves during the secondary collision, the shearing load that is required to shear the coupling member60is first applied to the holding member30, and then a load that causes the deformation of the energy absorbing member50is applied to the holding member30. Thus, a peak load for the impact absorption during the secondary collision is substantially equal to a load that uncouples the coupling members60(the six resin pins in this embodiment).

Note that, for example, expression “the coupling member60uncouples” does not only mean the coupling member60is completely sheared in the case where the coupling member60is arranged in a state of being sheared as in this embodiment. For example, in the case where the coupling member60as the resin pin is deformed to such extent that the shearing load exceeds the peak, the coupling member60can substantially uncouple the fixture member40and the holding member30(the fixture bracket32). In addition, the opening51of the energy absorbing member50may be engaged with the engaging section45of the fixture member40at timing after a time point of uncoupling by the coupling member60. Accordingly, in the case where a moving distance of the fixture bracket32that is required for the coupling member60to uncouple is set as L, the distance D shown inFIG. 6may be D≥L.

After the opening51is engaged with the engaging section45as shown inFIG. 7, the fixture bracket32moves forward in the axial direction. Consequently, the coupling member60as the resin pin is completely sheared, and the energy absorbing member50is modified as shown inFIG. 8. In this way, the energy absorbing member50absorbs the impact energy generated by the secondary collision. Note that the coupling member60as the resin pin may completely be sheared before the opening51is engaged with the engaging section45.

As it has been described so far, the steering column10according to this embodiment includes: the cylindrical member20that holds the steering shaft15in such a manner as to allow the extension and the contraction thereof in the axial direction; the holding member30that holds the cylindrical member20; the fixture member40that is fixed to the vehicle body120; the coupling member60that couples the fixture member40and the holding member30; and the energy absorbing member50. The uncoupling by the coupling member60occurs when the holding member30moves forward for a specified distance in the axial direction. The energy absorbing member50is partially fixed to the holding member30. The fixture member40has the engaging section45, which is arranged at the position where the engaging section45is engaged with the opening51as the engaged section of the energy absorbing member50in the case where the holding member30moves forward for the specified distance or longer in the axial direction during the secondary collision.

With such a configuration, when the holding member30moves forward for the specified distance in the axial direction, the uncoupling by the coupling member60occurs. Then, at the time point onward, the engaged section (the opening51in this embodiment) of the energy absorbing member50is engaged with the fixture member40. As a result, a time gap between uncoupling timing by the coupling member60and initiation timing of the deformation of the energy absorbing member50is generated, and thus the peak load during the impact absorbing operation becomes relatively small. In addition, in the impact absorbing operation, the energy absorbing member50is engaged with the engaging section45of the fixture member40, which is fixed to the vehicle body120. That is, a portion of the energy absorbing member50that is subjected to the engagement after the secondary collision does not move with respect to the vehicle body120. Thus, such an engaged state is stabilized. Furthermore, in the impact absorbing operation, the part of the energy absorbing member50is fixed in advance to the holding member30, which causes the deformation of the energy absorbing member50when moving with respect to the vehicle body120. For such a reason, the holding member30and the part of the energy absorbing member50can be firmly joined to each other by using a specified joining method such as welding, for example. As a result, for example, such a possibility that the energy absorbing member50is deformed as being designed (as being estimated) during the secondary collision is increased. As described above, the steering column10according to this embodiment can perform the appropriate impact absorbing operation with the simple configuration.

In this embodiment, the engaging section45is provided in the projected manner from the fixture member40. The engaged section corresponds to the opening51, which is provided in the energy absorbing member50, and in which the engaging section45is arranged in the penetrating manner, and the opening51is formed in such size that the clearance D is provided at the rear of the engaging section45in the axial direction. On the portion of the engaging section45that is exposed from the opening51, the head72is arranged. The head72has a larger portion than the opening51when seen in the projected direction of the engaging section45, and the head72is arranged separately from the peripheral edge of the opening51in the projected direction.

With such a configuration, the impact absorbing operation is performed in such a simple configuration that the engaging section45, which is provided in the projected manner from the fixture member40, is stuck by the opening51of the energy absorbing member50. In addition, due to the provision of the head72, during the normal time and during the impact absorbing operation, the disengagement of the opening51of the energy absorbing member50from the engaging section45is prevented. This stabilizes the impact absorbing operation.

In this embodiment, the head72is the head72of the bolt70that fastens the fixture member40and the vehicle body120to each other, so as to fix the fixture member40to the vehicle body120. The engaging section45has the through hole41, which causes the shaft section71of the bolt70to extend through the engaging section45in the projected direction. The projection length of the engaging section45from the fixture member40is greater than the thickness of the peripheral edge of the opening51in the plate-shaped energy absorbing member50.

Just as described, in this embodiment, the fixture member40is fixed to the vehicle body120by the bolt70, which extends through the through hole41provided in the engaging section45of the fixture member40. That is, the bolt70, which firmly fixes the fixture member40to the vehicle body120, is used for the engagement of the engaging section45with the energy absorbing member50. Thus, engagement strength is improved, for example. In addition, since the projection length of the engaging section45is greater than the thickness of the peripheral edge of the opening51(the annular section52), the fastening force by the bolt70is not substantially applied to the energy absorbing member50. That is, the fastening force by the bolt70does not hinder the uncoupling by the coupling member60(that is, the movement of the holding member30). Accordingly, for example, in the case where the resin pin is used as the coupling member60as in this embodiment, the resin pin only needs to have such strength that the resin pin can endure the load at the time of the position adjustment of the steering wheel, for example. As a result, the peak load during the impact absorbing operation can be reduced.

The description has been made so far on the steering column10according to the embodiment. However, the steering column10may include a fixture member and an energy absorbing member in a different mode from the mode shown inFIG. 1toFIG. 4. A description will hereinafter be centered on different points from the above embodiment in modified embodiments of the fixture member and the energy absorbing member.

First Modified Embodiment

FIG. 9is a view of a structure of a fixture member40aaccording to a first modified embodiment of the embodiment and a periphery thereof. In regard to the fixture member40aaccording to this modified embodiment shown inFIG. 9, an engaging section46is formed when a member manufactured as a separate member from the fixture member40ais attached to the fixture member40a.More specifically, the engaging section46is formed of a circular tube member48that is attached to an attachment hole47provided in the fixture member40asuch that a part of the circular tube member48in a tube axial direction is projected from the fixture member40a.The shaft section71of the bolt70is arranged in such a manner as to extend through the circular tube member48in the tube axial direction. That is, the part of the through hole41, which causes the shaft section71to penetrate, in the fixture member40ais formed of the circular tube member48.

With such a configuration, the circular tube member48, which forms the engaging section46in the projected shape, is arranged as the separate member in the metallic fixture member40a.Accordingly, for example, when compared to the fixture member40according to the above embodiment that integrally includes the engaging section45in the projected shape, the fixture member40acan easily be manufactured. In addition, a projection length of the engaging section46from the fixture member40acan be changed by changing a length of the circular tube member48in the tube axial direction. Thus, for example, when the thickness of the peripheral edge of the opening51in the energy absorbing member50is changed, the projection length of the engaging section46can easily be changed.

Second Modified Embodiment

FIG. 10is a view of a structure of a fixture member40baccording to a second modified embodiment of the embodiment and a periphery thereof. The fixture member40baccording to this modified embodiment shown inFIG. 10is fixed to the vehicle body120by a stepped bolt70a,and a step73of the stepped bolt70aas a separate member from the fixture member40bis provided as an engaging section49.

That is, in this modified embodiment, the engaging section49is the step73of the stepped bolt70athat fastens the fixture member40band the vehicle body120to each other, so as to fix the fixture member40bto the vehicle body120. In other words, the head72that is provided in an exposed portion of the engaging section49from the opening51and has a larger portion than the opening51is the head72of the stepped bolt70a.In addition, a thickness of the step73in the bolt-axis direction is greater than the thickness of the peripheral edge of the opening51in the plate-shaped energy absorbing member50.

With such a configuration, processing to provide an engaging section in a projected shape in the metallic fixture member40bis unnecessary, and a surface on the energy absorbing member50side of the fixture member40bcan be flat. In addition, since the step73of the stepped bolt70ais used as the engaging section49, the distance of the clearance D inFIG. 10can be changed by replacing the stepped bolt70a(by changing to the other stepped bolt70ahaving the step73in different size). For such a reason, an amount of the time gap between the uncoupling timing by the coupling member60and the initiation timing of the deformation of the energy absorbing member50can be adjusted by replacing the stepped bolt70a,for example.

Third Modified Embodiment

FIG. 11is a view illustrating characteristics of an energy absorbing member50aaccording to a third modified embodiment of the embodiment. Note thatFIG. 11shows a cross section of the fixture member40and a periphery thereof in an X-Y plane that passes the axis of the bolt70.

In this modified embodiment, the engaging section45of the fixture member40is arranged in a state of penetrating the opening51of the energy absorbing member50a,and the peripheral edge of the opening51is located between the head72of the bolt70and the fixture member40. In regard to such a configuration, this modified embodiment is the same as the above embodiment.

Meanwhile, in this modified embodiment, the peripheral edge of the opening51in the energy absorbing member50ais formed with a convex section57that is projected toward the head72. In such a point, this modified embodiment differs from the above embodiment.

Just as described, in this modified embodiment, the annular section52having the opening51is configured to have a thickness fitted to the clearance between the head72of the bolt70and the fixture member40(the clearance G inFIG. 6) and have the convex section57that is in point contact with the head72of the bolt70.

That is, the annular section52, which has the opening51, is arranged in such a manner as to hardly receive the fastening force by the bolt70, and the movement of the annular section52in the bolt-axis direction is restricted by the convex section57. Accordingly, the head72of the bolt70does not substantially hinder the forward movement of the annular section52in the axial direction (in the positive Z-axis direction) at the time of the engagement of the opening51with the engaging section45, and thus rattling of the annular section52is suppressed. In this way, for example, it is possible to suppress abnormal noise that is produced by the rattling of the annular section52, damage to the annular section52, or the like without degrading the stability of the impact absorbing operation.

Note that, although the two convex sections57are formed on the peripheral edge of the opening51in this modified embodiment, the at least one convex section57may be formed. In addition, a concave section is formed on a back side of the convex section57in the annular section52. However, such a concave section may not be formed. That is, the back side of the convex section57in the annular section52may have a flat shape. Furthermore, the convex section57may be formed on a surface on the fixture member40side of the annular section52. That is, the convex section57may be provided as a projected portion toward the fixture member40on the peripheral edge of the opening51. Also, in such a case, the annular section52, which has the opening51, can be arranged in such a manner as to hardly receive the fastening force by the bolt70, and the movement of the annular section52in the bolt-axis direction is restricted by the convex section57.

Fourth Modified Embodiment

FIG. 12is a view illustrating characteristics of an energy absorbing member50baccording to a fourth modified embodiment of the embodiment. In order to clarify a structural relationship between the energy absorbing member50band the bolt70,FIG. 12only shows the energy absorbing member50band the bolt70. In addition, the energy absorbing member50bis shown in the cross-sectional shape at the same position as inFIG. 5, and the bolt70is shown in a side view of a state where the bolt70separates from the energy absorbing member50b.

In this modified embodiment, the annular section52, which has the opening51, in the energy absorbing member50bhas a curved shape to be projected toward the head72. Accordingly, in the case where the engaging section45of the fixture member40is arranged in the state of penetrating the opening51and the fixture member40is fixed to the vehicle body120by the bolt70(for example, seeFIG. 6), the annular section52, which is curved to be projected toward the head72, comes in line or point contact with the head72of the bolt70.

That is, the annular section52, which has the opening51, can be arranged in such a manner as to hardly receive the fastening force by the bolt70, and a small area of the annular section52comes in contact with each of the head72and the fixture member40. In this way, the movement of the annular section52in the bolt-axis direction can be restricted. Accordingly, the head72of the bolt70does not substantially hinder the forward movement of the annular section52in the axial direction (in the positive Z-axis direction) at the time of the engagement of the opening51with the engaging section45, and thus the rattling of the annular section52is suppressed. In this way, for example, it is possible to suppress the abnormal noise that is produced by the rattling of the annular section52, the damage to the annular section52, or the like without degrading the stability of the impact absorbing operation.

Note that the annular section52may be bent to be projected toward the head72. In this way, the contact area of the annular section52with the head72is further reduced. In addition, the annular section52may be curved or bent to be projected toward the fixture member40. That is, the annular section52may be curved or bent in a reverse direction from the direction shown inFIG. 12. Also, in such a case, the annular section52, which has the opening51, can be arranged in such a manner as to hardly receive the fastening force by the bolt70. Furthermore, due to the contact of the annular section52with both of the head72and the fixture member40, the movement of the annular section52in the bolt-axis direction is suppressed.

Other Embodiments

The description has been made so far on the steering column according to the disclosure on the basis of the embodiment and the modified embodiments thereof. However, the disclosure is not limited to the embodiment and the modified embodiments described above. Various modifications that are conceived by persons skilled in the art and are made to the embodiment and the modified embodiments described above, and aspects that are constructed by combining the plural constituent elements described above are also included in the scope of the disclosure unless departing from the gist of the disclosure.

For example, in the steering column10according to the embodiment, the outer tube21and the inner tube22each has the cylindrical shape. However, the shape of each of these outer tube21and inner tube22is not limited to the cylindrical shape. For example, a cross-sectional shape of each of the outer tube21and the inner tube22that is orthogonal to the axial direction may be a polygonal shape, an oval shape, an elongated circular shape, or the like.

In this embodiment, the energy absorbing member50is the plate-shaped metallic member. However, the shape and the type of the energy absorbing member provided in the steering column10are not particularly limited. For example, a wavy metallic plate or a metallic tube formed in an accordion shape may be adopted as the energy absorbing member provided in the steering column10.

The coupling member60may be a member other than the resin pin. For example, the coupling member60may be formed by a resinous or metallic annular member that couples the fixture member40and the fixture bracket32.

The engagement structure between the fixture member40and the energy absorbing member50is not particularly limited. For example, the deformation of the energy absorbing member50may be initiated when a projection provided in the energy absorbing member50is engaged with a part of the fixture member40.

For example, the head72of the bolt70may function as an engaging section that is provided in a projected manner from the fixture member40. In such a case, for example, a screw hole is provided in the head72of the bolt70, and another bolt having a larger head than the head72is screwed to the screw hole. In this way, the other bolt can function to prevent the opening51of the energy absorbing member50from being disengaged from the engaging section (the head72).

The steering column according to the disclosure is useful as a steering column that is provided in the vehicle such as the automobile and capable of the position adjustment of the steering wheel.