JP2010188901A - Energy absorption steering column - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an energy absorption steering column capable of easily and properly setting a motion start load and an in-motion load between a first cylindrical member and a second cylindrical member with an inexpensive constitution. <P>SOLUTION: A resilient bushing 30 is installed between a first diameter-expanded part 11 and a first holding part 21 at the front side of a vehicle, and a second diameter-expanded part 21 is press-fitted into a second holding part 22 at the rear side of the vehicle. A steering shaft 1 is held in a state where the axial direction relative motion of the first cylindrical member (inner tube 10) is blocked with respect to the second cylindrical member (outer tube 20) so as to apply the motion start load. Further, an energy absorption block 50 having a friction engagement part FP is mounted to a plate-like member (energy absorption plate 40) to apply the in-motion load. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an energy absorbing steering column, and more particularly to an energy absorbing steering column that absorbs energy applied to a steering shaft of a vehicle.

  Energy absorption steering columns mounted on vehicles are widely known as a means to alleviate the impact on the steering wheel by giving the steering column the characteristic of absorbing energy, and various structures are adopted. Yes. For example, a ball type with a ball interposed between the outer tube and the inner tube of the steering column, a mesh type with a metal mesh structure for the steering column, silicon rubber sealed in the lower tube, and the upper tube entering from the slit A silicon rubber type configured such that silicon rubber is ejected is used.

  And in the following Patent Document 1, “in the energy absorbing steering column, regarding the relative movement in the axial direction between the first cylindrical member and the second cylindrical member constituting the column, the movement start load is easily and appropriately set. “Providing an energy-absorbing steering column that can be set” as an object, “diameter interposed between the first press-fit portion of the first cylindrical member and the first holding portion of the second cylindrical member. A metal elastic bushing that imparts an elastic force in the direction, and the metal elastic bushing is urged in the radial direction with respect to the first press-fitting portion and the first holding portion, and the first tubular shape with respect to the second tubular member The steering shaft is held in a state where the relative movement of the member in the axial direction is prevented. Further, “the first cylindrical member includes the second press-fit portion and the vicinity of the vehicle front opening end is cut off in a predetermined range in the axial direction. A second cylindrical member having a notch It urges against the holding portion in the radial direction to hold the steering shaft "It has been proposed while preventing axial relative movement of the first tubular member relative to the second tubular member.

JP 2007-168869 A

  According to the steering column described in Patent Document 1, the movement start load can be easily and appropriately set. However, in the vicinity of the vehicle rear opening end, the first press-fitting portion and the second press-fitting portion of the first tubular member are provided. The urging force of the metal elastic bush interposed between the first holding portion of the tubular member and the second press-fit portion of the first tubular member having the notch portion and the second portion in the vicinity of the vehicle front opening end. The axial movement of the first cylindrical member relative to the second cylindrical member is prevented by an urging force between the second cylindrical member and the second holding portion. However, if the metal elastic bushing is arranged near the vehicle rear opening end, a large repeated load is applied compared to the vehicle front opening end vicinity, so a metal elastic bushing that can withstand this is required. Inevitably expensive. Moreover, although it is necessary to form a plane part with respect to an inner tube, since a burr | flash is formed according to a general cutting process, it will be necessary to remove this. In addition, in order to ensure the necessary rigidity, it is necessary to use a tube material having a plate thickness that takes into account the thinning caused by the cutting process, resulting in waste.

  Accordingly, the present invention absorbs energy that can easily and appropriately set the movement start load and the moving load between the first cylindrical member and the second cylindrical member while ensuring the necessary rigidity with an inexpensive configuration. It is an object to provide a steering column.

  To achieve the above object, the present invention provides a first cylindrical member that accommodates a steering shaft of a vehicle and supports the vehicle so as to be rotatable around the shaft, and the first cylinder that accommodates the first cylindrical member and is always in the first cylinder. A second cylindrical member that holds the cylindrical member in a predetermined position, and an axial relative movement of the first cylindrical member relative to the second cylindrical member when a load greater than a predetermined value is applied to the steering shaft. In the energy-absorbing steering column configured so that the second cylindrical member has a first holding portion formed on an inner surface at a position spaced apart from the vehicle rear opening end by a predetermined distance in the axial direction. The 1st cylindrical member has the 1st enlarged diameter part by which the vehicle front opening end vicinity was diameter-expanded, and the said 2nd cylindrical member was formed in the inner surface of the vehicle rear opening end vicinity. The first cylinder has a holding portion The member has a second diameter-expanded portion whose diameter is increased by a predetermined distance from the front opening end of the vehicle in the axial direction, and a position where the second diameter-expanded portion is held by the second holding portion. A diameter-reduced portion continuously reduced in diameter in the circumferential direction between the first cylindrical member and the vicinity of the vehicle rear opening end, and a plane portion in which a part of the outer peripheral surface of the reduced-diameter portion is cut off. An elastic bushing interposed between the first enlarged diameter portion and the first holding portion and applying an elastic force in the radial direction; And an energy absorption block having a friction engagement portion that is attached to the plate member and guided while applying a frictional force during relative movement.

  In the energy absorbing steering column, the energy absorbing block is a bent groove that introduces the plate-like member from the front side of the vehicle and leads out to the rear side of the vehicle to form the friction engagement portion, It is preferable to have a bent groove that opens only on one side and at least one protrusion that locks the plate-like member with respect to the opening of the bent groove. Furthermore, the energy absorption block may be formed such that the bent groove constitutes a plurality of friction engagement portions. In addition, the said energy absorption block can be formed in a single member with a synthetic resin.

  Since this invention is comprised as mentioned above, there exist the following effects. That is, in the energy absorbing steering column of the present invention, the second cylindrical member has the first holding portion formed on the inner surface at a position spaced apart from the vehicle rear opening end by a predetermined distance in the axial direction. And the second cylindrical member has a second holding portion formed on the inner surface near the vehicle rear opening end. And the first tubular member has a second diameter-expanded portion whose diameter is increased by a predetermined distance from the front opening end of the vehicle in the axial direction, and the first diameter-expanded portion and the first holding portion. An elastic bushing that provides elastic force in the radial direction between them, a plate-like member that is fixed to the flat surface and extends in the direction toward the rear opening end of the vehicle, and a friction that is attached to the plate-like member and moves relative to it. As an energy absorption block having a friction engagement portion that guides while applying force Therefore, with respect to the diameter of the first enlarged portion and the first holding portion, the axial load reacts relatively insensitive to the second enlarged portion and the second holding portion and is displaced with respect to the external force. The second diameter-expanded portion and the second holding portion are more sensitive to the press-fitting allowance than the first diameter-expanded portion and the first holding portion. In contrast, the plate-like member can be securely held by the energy absorption block, guided while applying frictional force, and moved while absorbing energy by plastic deformation of the plate-like member. As a so-called handling load, a moving load can be appropriately applied. Thus, it is possible to easily and appropriately set the movement start load in the axial relative movement between the first cylindrical member and the second cylindrical member while ensuring the necessary rigidity with an inexpensive configuration, and the movement. The medium load can also be set appropriately by an energy absorption block having a simple configuration. In particular, the energy absorption block has a smaller number of parts than the conventional one and is easy to assemble, so that the cost can be reduced.

  If the energy absorption block has the bent groove and the protrusion, the energy absorption block can be easily attached to the plate-like member, and can be reliably prevented from falling off the plate-like member. . Furthermore, if the bent groove constitutes a plurality of friction engagement portions, the handling load on the plate-like member at the time of energy absorption can be easily adjusted. And if an energy absorption block is formed in a single member with a synthetic resin, it can manufacture cheaply and easily.

1 is a cross-sectional view of an energy absorption steering column according to an embodiment of the present invention. It is sectional drawing which expands and shows the relationship between the inner tube in FIG. 1, and an outer tube. It is a figure which shows the plane and cross section of the convex part by the drawing process of the elastic bush in one Embodiment of this invention. It is the side view which looked at the energy absorption steering column which concerns on one Embodiment of this invention from the vehicle rear side. It is a top view of the energy absorption block with which it uses for one Embodiment of this invention. It is a front view of the energy absorption block with which it uses for one Embodiment of this invention. It is a front view of the energy absorption block which concerns on the other Example with which it uses for one Embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of an energy absorbing steering column according to an embodiment of the present invention. A steering shaft 1 includes a cylindrical upper shaft 1a having a steering wheel (not shown) connected to a rear end portion thereof, The lower shaft 1b is spline-coupled to the inner cylindrical surface of the upper shaft 1a. That is, the upper shaft 1a and the lower shaft 1b are connected so as to be relatively movable in the axial direction but not to be relatively rotatable, and the front end portion of the lower shaft 1b is connected to a steering mechanism (not shown). The steering shaft 1 is supported on a vehicle body (not shown) by a bracket (not shown) via a column housing 2 so as to form a predetermined angle (for example, 25 °) with respect to a vehicle floor (not shown). Has been.

  A metal inner tube 10 is provided in the column housing 2 as a first cylindrical member that houses the steering shaft 1 and supports the steering shaft 1 so as to be rotatable about an axis. That is, the upper shaft 1 a accommodated in the inner tube 10 is rotatably supported by the rear end portion of the inner tube 10 via the bearing 3. However, the relative movement in the axial direction between the upper shaft 1a and the inner tube 10 is restricted, and the upper shaft 1a and the inner tube 10 are configured to be able to move in the axial direction as a unit. Further, a metal outer tube 20 is provided as a second cylindrical member that accommodates the first cylindrical member and normally holds the first cylindrical member in a predetermined position. And when the load more than predetermined value is applied with respect to the steering shaft 1, it is comprised so that the axial direction relative movement of the inner tube 10 with respect to the outer tube 20 (as a result, the axial direction movement of the upper shaft 1a) is permitted. The inner tube 10 and the outer tube 20 of this embodiment function as energy absorbing means together with the metal elastic bush 30 and the like.

  The outer tube 20 is supported by the column housing 2 via bearings 3a and 3b, and the outer tube 20 is pressed against and held by the inner surface of the column housing 2 by friction mechanisms 4a and 4b using disc springs. . Therefore, the sliding property in the thrust direction can be ensured without causing play in the steering wheel (not shown), but the space between the column housing 2 and the outer tube 20 does not function as an energy absorbing means.

  The outer tube 20 of the present embodiment has a first holding portion 21 formed on the inner surface at a predetermined distance in the axial direction from the vehicle rear opening end (hereinafter referred to as the rear opening end), and the rear opening end. A second holding portion 22 is formed on the inner surface in the vicinity. The first holding portion 21 is configured by an annular recess formed on the inner peripheral surface of the outer tube 20, and the second holding portion 22 extends integrally from the inner peripheral surface of the outer tube 20 in the axial direction. It is comprised by the formed annular convex part.

  On the other hand, the inner tube 10 has a first diameter-expanded portion 11 whose diameter is increased in the vicinity of an opening end (hereinafter referred to as a front opening end) in front of the vehicle, and a portion spaced apart from the front opening end by a predetermined distance in the axial direction. Has a second enlarged-diameter portion 12 having an enlarged diameter. The first enlarged diameter portion 11 and the second enlarged diameter portion 12 in the present embodiment are formed so as to bulge outward in the radial direction of the inner tube 10. Further, the portions of the first enlarged diameter portion 11 and the second enlarged diameter portion 12 that face the first holding portion 21 and the second holding portion 22 are cut out to be flat.

  As shown in FIG. 2 in an enlarged manner, an elastic bush 30 is interposed between the first enlarged diameter portion 11 and the first holding portion 21, and the elastic force is applied in the radial direction. Yes. The elastic bush 30 of this embodiment is formed of, for example, stainless steel. As shown in FIG. 3, as shown in FIG. 3, a cylindrical body portion 31 having a C-shaped cross section and a plurality of convex portions (representatively) in the circumferential direction of the cylindrical body portion 31. 32). The convex portions 32 of the present embodiment are formed by drawing so as to extend inward in the radial direction of the cylindrical body 31 at a predetermined interval in the circumferential direction of the cylindrical body 31. The cross section of each convex portion 32 is formed in a trapezoidal shape, but may be formed so that the outer side is a curved surface.

  Thus, when the elastic bush 30 configured as described above is interposed between the first enlarged diameter portion 11 and the first holding portion 21 as shown in FIG. 1 and FIG. 32 is compressed and deformed, and its restoring elastic force is applied in the radial direction between the two, that is, between the inner tube 10 and the outer tube 20. This elastic force ensures a frictional force between the elastic bush 30 and the inner tube 10 and the outer tube 20, so that the steering shaft 1 can be operated in a state where the axial relative movement of the inner tube 10 and the outer tube 20 is prevented. Retained. The height of each convex portion 32 formed by drawing is set to a value in the vicinity of the setting, and the first diameter-expanded portion 11 side of the inner tube 10 is an axis with respect to the radial dimensions of the inner tube 10 and the outer tube 20. The directional load is set so as to be relatively insensitive and to be relatively displaced with respect to an external force. On the other hand, the second enlarged diameter portion 12 is press-fitted and held in the second holding portion 22, and the second enlarged diameter portion 12 side of the inner tube 10 is press-fitted between the inner tube 10 and the outer tube 20. The axial load is set so that it reacts relatively sensitively to the margin and is relatively difficult to displace relative to the external force. Therefore, the inner tube 10 is appropriately held with respect to the outer tube 20 without causing play in the steering wheel (not shown).

  Further, the inner tube 10 has a part in the circumferential direction continuously between the position where the second enlarged diameter portion 12 is held by the second holding portion 22 and the vicinity of the vehicle rear opening end of the inner tube 10. While having the reduced diameter part 13 reduced in diameter, it has the plane part 14 by which a part of outer peripheral surface of this reduced diameter part 13 was excised. Note that the inner tube 10 of the present embodiment has an end mill (FIG. 1) after the pipe material is subjected to plastic forming by hydroforming to form the first and second enlarged diameter portions 11 and 12 and the reduced diameter portion 13. The flat portion 14 is formed by cutting a part of the outer peripheral surface of the reduced diameter portion 13. In addition, since the inner tube 10 of the present embodiment is formed by cutting a part of the outer peripheral surface of the reduced diameter portion 13 to form the flat portion 14, the section modulus thereof is compared with the section modulus of the conventional structure. It becomes relatively large and the required rigidity can be easily secured.

  Thus, as shown in FIG. 1, an axial space SP is formed between the outer peripheral surfaces of the reduced diameter portion 13 and the flat portion 14 and the inner peripheral surface of the inner tube 10. An energy absorbing plate (commonly referred to as an EA plate, hereinafter simply referred to as a plate) 40, which is a long elastic plate-like member, is interposed, and one end thereof is fixed to the flat portion 14 by welding. In addition, it is good also as fixing using a pin, caulking, a rivet, etc.

  Further, as shown in FIG. 1, an energy absorption block (hereinafter simply referred to as a block) 50 is attached to the plate 40 in the vicinity of the rear opening end of the outer tube 20. The block 50 of the present embodiment is formed as a single member having the shape shown in FIGS. 4 to 6 with a synthetic resin. That is, the plate 40 is introduced from the front side of the vehicle (left side of FIG. 1) and led out to the rear side of the vehicle (right side of FIG. 1) to constitute a friction engagement portion (indicated by FP in FIG. 6). Is formed. The bent groove 51 is opened only in one side of the vehicle (left side in FIG. 4), and two protrusions 52 and 53 for locking the plate 40 are formed integrally with the block body. Yes. Therefore, when the block 50 is mounted on the plate 40, the plate 40 is bent from the side of the vehicle (left side in FIG. 4) and is received in the bending groove 51 across the two protrusions 52 and 53. Well, since the plate 40 is securely held in the bending groove 51, it does not fall off.

  When the block 50 and the plate 40 move relative to each other and the plate 40 moves in the bending groove 51, a frictional force is applied to the plate 40 by the friction engagement portion FP, and the plastic deformation of the plate 40 is performed. Therefore, a so-called handling load is applied. In this embodiment, the friction engagement portions FP are formed at two locations as shown in FIG. 6, but if the bent grooves 55 having the shape shown in FIG. 7 are formed, for example, the friction engagement portions FP are formed at four locations. The Thus, by appropriately forming the plurality of friction engagement portions FP, the handling load by the block 50 on the plate 40 during energy absorption can be easily adjusted.

  Furthermore, in this embodiment, after the outer peripheral surface of the inner tube 10 is cut in the axial direction by an end mill (not shown) to form the flat surface portion 14, the inner tube 10 is drilled by the end mill and the locking hole is formed. 16 is formed. On the other hand, a locking pin 60 is fixed to the outer tube 20, and the inner tube 10 and the outer tube 20 are assembled in a state where the locking pin 60 is inserted into the locking hole 16. As a result, as shown in FIG. 1, the locking pin 60 protrudes inside the outer tube 20 so as to be in contact with and locked to the inner wall surface of the locking hole 16 in front of the vehicle. The dimension is set so as not to contact the outer surface of the flat portion 14. Thus, the inner tube 10 is reliably prevented from dropping from the outer tube 20 to the vehicle rear side. The locking pin 60 is not tightly fitted to the locking hole 16, and there is no problem even if the rear side of the locking hole 16 is open to the vehicle. What is necessary is just to be comprised so that it may touch.

  The operation of the energy absorbing steering column having the above-described configuration will be described. Normally, the second expanded portion 12 of the inner tube 10 is press-fitted into the second holding portion 22 of the outer tube 20 in the state shown in FIG. At the same time, the first enlarged diameter portion 11 of the inner tube 10 and the first holding portion 21 of the outer tube 20 are held in a pressed state by the elastic force of the elastic bush 30. At the position shown in FIG. The tube 10 and the outer tube 20 are held in a state in which relative movement in the axial direction is prevented.

  Next, when a load equal to or greater than a predetermined value is applied to the steering shaft 1 and the steering shaft 1 moves forward together with the inner tube 10, the first diameter-expanded portion 11 of the inner tube 10 becomes the first holding portion 21 of the outer tube 20 and The second expanded portion 12 of the inner tube 10 is detached from the second holding portion 22 of the outer tube 20 while being separated from the elastic bush 30. The load at this time is the movement start load of the steering shaft 1. Therefore, the movement is started by the first and second enlarged diameter portions 11 and 12, the first and second holding portions 21 and 22, and the elastic bush 30. A load adding portion is configured. The movement start load includes the outer diameters of the first and second enlarged diameter portions 11 and 12, the inner diameters of the first and second holding portions 21 and 22, the plate thickness of the elastic bush 30, and the convex portion 32. By adjusting either the total number or the height of each convex portion 32, it is possible to set a stable and appropriate load without causing a change with time or a temperature change of the movement start load.

  When a larger load is applied to the steering shaft 1, the plate 40 moves forward while being guided by the block 50. During this time, the plate 40 is given a frictional force by the frictional engagement portion FP of the block 50 and moves while absorbing energy due to its plastic deformation, so that a handling load is given. As described above, this handling load can be adjusted by adjusting the number and shape of the friction engagement portions FP. Furthermore, a desired load can be set by forming a protrusion, a concave portion, a notch or the like on the plate 40. The handling load application start stroke is set by adjusting a gap (indicated by Ls in FIG. 1) between the front end surface of the block 50 and the rear end surface of the outer tube 20 when the block 50 is mounted on the plate 40. be able to.

  Thus, desired energy absorption characteristics can be secured by the energy absorption steering column 1 configured as described above. First, when a load is applied to the steering shaft 1 and exceeds the above-described movement start load, the inner tube 10 starts to move relative to the outer tube 20. That is, the frictional force between the second enlarged diameter portion 12 of the inner tube 10 and the second holding portion 22 of the outer tube 20, the elastic bush 30, the first enlarged diameter portion 11, and the first holding portion 21. The inner tube 10 and the outer tube 20 move relative to each other in the axial direction against the frictional force between them, and a free state occurs when a predetermined stroke is exceeded.

  Further, after the stroke of the steering shaft 1 moves through the gap Ls between the block 50 and the rear end surface of the outer tube 20, a handling load is applied, and a substantially constant load by the block 50 is applied to the steering shaft 1. The inner tube 10 moves relative to the outer tube 20 together with the steering shaft 1. As a result, energy is appropriately absorbed even when the steering shaft 1 is making a stroke.

  As described above, in the energy absorbing steering column 1 described above, the movement start load adding portion is formed by the first and second enlarged diameter portions 11 and 12, the first and second holding portions 21 and 22, and the elastic bush 30. In addition, since the moving load addition portion is configured by the plate 40, the block 50, etc., the movement start load and the moving load in the axial relative movement between the inner tube 10 and the outer tube 20 are individually provided. It can be set to an appropriate value.

1 Steering shaft 2 Column housing 10 Inner tube (first tubular member)
11 1st diameter expansion part 12 2nd diameter expansion part 13 diameter reduction part 14 plane part 20 outer tube (2nd cylindrical member)
21 1st holding | maintenance part 22 2nd holding | maintenance part 23 Guide part 30 Elastic bush 40 Energy absorption plate 50 Energy absorption block

Claims (4)

  A first tubular member that accommodates a steering shaft of a vehicle and supports the vehicle so as to be rotatable about an axis, and a second tubular member that accommodates the first tubular member and always holds the first tubular member in a predetermined position. An energy absorbing steering column configured to allow axial movement of the first tubular member relative to the second tubular member when a load greater than a predetermined value is applied to the member and the steering shaft; The second cylindrical member has a first holding portion formed on the inner surface at a position spaced apart from the vehicle rear opening end by a predetermined distance in the axial direction, and the first cylindrical member is located near the vehicle front opening end. The first tubular member has a first enlarged diameter portion and a second holding member formed on the inner surface near the vehicle rear opening end, and the first tubular member. Is axially from the front opening end of the vehicle The vicinity of the vehicle rear opening end of the first tubular member from the second enlarged diameter portion in which the portion separated by a constant distance is enlarged, and the position where the second enlarged diameter portion is held by the second holding portion A diameter-reduced part continuously reduced in diameter in the circumferential direction and a plane part obtained by cutting out a part of the outer peripheral surface of the reduced-diameter part. An elastic bushing interposed between the diameter part and the first holding part to impart elastic force in the radial direction; a plate-like member fixed to the flat part and extending toward the vehicle rear opening end; and the plate An energy-absorbing steering column comprising: an energy-absorbing block having a frictional engagement portion that is attached to a member and guided while applying a frictional force during relative movement.   The energy absorption block is a bent groove that introduces the plate-like member from the front side of the vehicle and leads out to the rear side of the vehicle to constitute the friction engagement portion, and is a bent groove that opens only to one side of the vehicle. 2. The energy absorbing steering column according to claim 1, further comprising at least one protrusion for locking the plate-like member with respect to the opening of the bent groove.   3. The energy absorbing steering column according to claim 2, wherein the energy absorbing block is formed so that the bent groove constitutes a plurality of friction engaging portions.   The energy absorption steering column according to any one of claims 1 to 3, wherein the energy absorption block is formed of a synthetic resin into a single member.

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