JP2003252209A - Impact absorbing steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain variation of the amount of absorption of impact energy. <P>SOLUTION: In this impact absorbing steering device 1, an outer jacket 10 of a steering column 4 and an inner jacket 11 are engaged so as to relatively slide. Swelling projections 42-44 are formed at an outer periphery 41 of the inner jacket 11 as a plurality of outward projections 29. A plurality of inward projections 28 are formed at an inner periphery 31 of the outer jacket 10 by caulking. The inward projections 28 and the outward projections 29 are engaged and both the jackets 10, 11 are kept in a press fit condition. Both the jackets 10, 11 are relatively slid at the time of collision, and engagement between projections is released at a roughly simultaneous timing to release the press fit condition. The amount of absorption of the impact energy by press fit of the jackets can be reduced, thus reducing the variation in the amount of absorption. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorbing steering device which absorbs a shock at the time of collision of an automobile.

[0002]

2. Description of the Related Art Some shock absorbing steering devices include a column contraction type that contracts a steering column at the time of a collision. For example, in this type of steering column, a pair of relatively slidable cylindrical tubes are fitted to each other at the fitting portion, and the outer circumferential surface of the fitting portion of the outer tube is caulked from the outside to thereby A protrusion is formed, and the protrusion is pressed against the outer circumference of the inner tube to achieve a press-fit state of both tubes. At the time of collision, during the shock absorption stroke, the protrusion of the outer tube rubs the outer circumference of the inner tube, causing a load that resists the impact force,
This absorbs impact energy.

However, the press-fitting load due to caulking is difficult to manage and easily varies, and it becomes difficult to obtain a predetermined absorbed energy with a predetermined shock absorbing stroke.
On the other hand, when another shock absorbing mechanism is also used together, variations in the buffer load of each shock absorbing mechanism are added, and it is very difficult to obtain a predetermined shock absorbing energy in a predetermined shock absorbing stroke. Therefore, the purpose of the present invention is to
It is an object of the present invention to provide a shock absorbing steering device that solves the above-mentioned technical problem and can reduce variations in the amount of shock energy absorption.

[0004]

According to a first aspect of the present invention, a steering column that rotatably supports a steering shaft has a tubular outer jacket and inner jacket that are fitted to each other. In a shock absorbing steering device in which both jackets relatively slide in the axial direction at the time of a collision to absorb the shock, both jackets are formed by engaging the inward projections of the outer jacket and the outer projections of the inner jacket that are formed by caulking. It is press-fitted, and the engagement of the inward projection and the outward projection is released due to the relative sliding of the two jackets at the time of collision, whereby the press-fitted state of both jackets is released.

According to the present invention, the protrusions are disengaged from each other at the time of a collision, and the press-fitting of the two jackets is released. Therefore, the amount of impact energy absorbed by the relative sliding of the jackets is remarkably reduced. As a result, the variation in absorption amount can be reduced. Further, even if another shock absorbing mechanism is added, it is possible to suppress variations in the absorbed energy as a whole to be small. According to a second aspect of the present invention, in the first aspect, the inward protrusions include at least a pair of inward protrusions that are separated from each other in the axial direction of the outer jacket, and the positions of the corresponding pair of inward protrusions are circumferentially displaced from each other. It is characterized by

By the way, when a plurality of inward projections are arranged at the same position in the circumferential direction along the axial direction, an outward projection corresponding to one of the inward projections due to relative movement at the time of collision,
There is a risk of interference with the other inward projection. Therefore, a pair of inward projections corresponding to each other are arranged so as to be displaced in the circumferential direction so that interference can be prevented. According to a third aspect of the present invention, in the first aspect, the outward projection of the inner jacket is
It includes a long bulging protrusion that is bulged long in the axial direction, and a pair of inward protrusions spaced apart in the axial direction of the outer jacket are engaged with both ends of the bulging protrusion in the axial direction. The positions of the protrusions are displaced from each other in the circumferential direction, and the circumferential width of the bulging protrusions is widened at the end portion on the open end side of the inner jacket and narrowed at the end portion on the other end side. It is characterized in that the protrusions are disengaged at substantially the same time.

According to the present invention, the effect of preventing interference can be obtained by a simple method of bulging the inner jacket. Moreover, the bulging formation can easily form the outward protrusions having partially different circumferential widths by using a generally inexpensive pipe material.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An impact absorbing steering apparatus (hereinafter, also simply referred to as a steering apparatus) according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a schematic configuration of the above steering device. The steering apparatus 1 includes a steering shaft 3 that transmits the movement of the steering wheel 2 for steering wheels (not shown) and a steering column 4 that rotatably supports the steering shaft 3 through the inside. Have The steering wheel 2 is connected to one end 5 of the steering shaft 3. A steering mechanism including a pinion, a rack shaft and the like is connected to the other end 6 of the steering shaft 3 via an integrally rotatable universal joint (not shown), an intermediate shaft and the like. When the steering wheel 2 is turned, its rotation is transmitted to the steering mechanism via the steering shaft 3, the universal joint, the intermediate shaft, etc., and thereby the wheels can be steered.

In the present steering apparatus 1, for example, the steering column 4 is attached to the vehicle body 7 so that the central axis of the steering shaft 3 is inclined with respect to the longitudinal direction of the vehicle and the steering wheel 2 is on the upper side.
Note that, hereinafter, the direction will be described based on a state in which the axial direction of the steering shaft 3 (hereinafter, also simply referred to as an axial direction) is horizontal and is aligned with the front-rear direction. Further, in each drawing, the front-back direction and the axial direction (see arrow S) are illustrated as necessary.

The steering shaft 3 has an upper shaft 8 which is arranged on the steering wheel 2 side and constitutes a rear portion thereof, and a lower shaft 9 which is connected to a front end of the upper shaft 8 and constitutes a front portion thereof. . The upper shaft 8 and the lower shaft 9 are connected to each other by a joint structure such as a spline structure so that they can move relative to each other in the axial direction and rotate integrally. The steering shaft 3 is supported by the steering column 4 via a plurality of bearings (not shown).

The steering column 4 accommodates an upper shaft 8 and is rotatably supported in a state of being positioned in the axial direction, and is an outer jacket 1 as a first tubular member.
0, an inner jacket 11 as a second tubular member that rotatably supports the lower shaft 9 in a state where it is positioned in the axial direction, a housing 12 fixed to the front part of the inner jacket 11, and an inner The lower bracket 13 fixed to the front part of the jacket 11 via the housing 12 and the upper bracket 14 fixed to the outer jacket 10. A configuration in which the housing 12 is omitted may be considered.

The outer jacket 10 of the steering column 4 is attached to the vehicle body 7 via an upper bracket 14, a support shaft 15, an upper fixing bracket 16, a connecting member 17, a fixing bolt 18, and the like. The inner jacket 11 includes the lower bracket 13 and the tilt center shaft 1.
It is attached to the vehicle body 7 by means of the lower fixing bracket 20 and the like. The steering system 1 also includes first to third impact absorbing mechanisms 21, 22, and 23 for alleviating the impact when the driver (driver) hits the steering wheel 2 during a collision.

The first shock absorbing mechanism 21 is constructed by fitting both jackets 10 and 11 of the steering column 4 to each other. At the time of a collision, both jackets 10 and 11 relatively slide in the axial direction, and the friction generated between the jackets 10 and 11 is used to absorb the shock. The second shock absorbing mechanism 22 has a so-called capsule structure, and has the above-described connecting member 31 and the like. The second shock absorbing mechanism 22 removably clamps the mounting seat of the upper fixing bracket 16 with the fixing bolt 18 inserted between the pair of clamping members of the connecting member 17, and penetrates the clamping member and the mounting seat. A resin pin for connection is provided. At the normal time before the collision, the upper fixing bracket 1
6 is held with a predetermined holding force. When an impact force exceeding the holding force is applied at the time of collision, the resin pin is sheared and broken, and the mounting seat is separated from between the holding members. At this time, the shock is absorbed by utilizing the friction generated between the mounting seat and the sandwiching member and the shear fracture of the resin pin.

The third shock absorbing mechanism 23 fixes the shock absorbing plate member folded back in a substantially U shape to the vehicle body side, and inserts the rod member engaging with the shock absorbing plate member through the inside of the folded back plate member to the steering column 4. Fixed to the side. With the relative movement at the time of collision, the rod absorbs the shock by squeezing the shock absorbing plate while plastically deforming it. In a normal state before the collision, the jackets 10 and 11 are press-fitted with the steering column 4 extending in the axial direction and held with a predetermined holding force to prevent the steering column 4 from unintentionally contracting. Then, at the time of a collision, when an impact force acts axially forward on the steering wheel 2, the steering columns 4 are contracted by the first to third impact absorbing mechanisms 21, 22, 23, and the impact is alleviated.

When the impact force from the driver acts on the steering wheel 2 at the time of absorbing the impact, each of the impact absorbing mechanisms 21, 22 and 23 produces a load against the impact force. Thereby, the impact energy is absorbed.
Then, the total absorption amount of the steering device 1 is obtained as the sum of the absorption amounts of impact energy (hereinafter, also simply referred to as absorption amounts) by the respective shock absorbing mechanisms 21, 22, 23. By the way, the absorption amount as a whole generally tends to vary from one steering device 1 to another. Therefore, in the present embodiment, the amount of absorption by the first shock absorbing mechanism 21 is reduced to suppress variations in the amount of absorption. On the other hand, if the load against the impact is originally reduced in order to reduce the absorption amount, there is a concern that the steering column 4 may inadvertently contract or the rigidity thereof may decrease during normal operation. There is no problem with the steering device 1.

In the first shock absorbing mechanism 21, as shown in FIGS. 2 to 5, the protrusions 28 and 29 formed on the jackets 10 and 11 are engaged with each other to achieve the press-fitted state. Inner circumference 31 of the front part of the outer jacket 10
Has a plurality of inward projections 28 formed by crimping and projecting inward in the radial direction. The plurality of inward protrusions 28 include inward protrusions 32 to 37 whose positions are different from each other. The outer periphery 41 of the rear portion of the inner jacket 11 has a plurality of outward protrusions 29 protruding outward in the radial direction.
The plurality of outward protrusions 29 are bulging protrusions 42 to 44, which will be described later, and whose positions are different from each other. The rear portion of the inner jacket 11 is fitted inside the front portion of the outer jacket 10 so that the inward protrusions 28 of the outer jacket 10 and the outward protrusions 29 of the inner jacket 11 are brought into contact with each other by the apex portions 52 and 53 facing each other. And press each other to engage each other. The front portion of the outer jacket 10 and the rear portion of the inner jacket 11 are fitted so as to be slidable relative to each other in the axial direction.

In the normal state before the collision, both jackets 10 and 1
In No. 1, in the press-fitted state, the rigidity of the steering column 4 can be maintained high. Then, at the time of collision, the protrusions 28 and 29 are disengaged from each other, and the press-fitted state of the jackets 10 and 11 is released. Therefore, the amount of impact energy absorbed by relative sliding of the jackets 10 and 11 is reduced. It can be made extremely small (see FIG. 6), and as a result, the variation in the amount of absorption by the first impact absorbing mechanism 21, and thus the variation in the amount of impact energy absorbed in a predetermined impact absorbing stroke, can be reduced in the steering device as a whole.

Further, as in the present embodiment, another shock absorbing mechanism, for example, the second and third shock absorbing mechanisms 22 and 23.
Even when adding the third shock absorbing mechanism 2, the amount of shock energy absorbed by the steering device 1 as a whole is
3 is mainly used (see FIG. 6). Therefore, the variation in the absorption amount as a whole is mainly determined by the third shock absorbing mechanism 23, is hardly affected by the mechanisms 21, 22, and becomes small. Furthermore, the third shock absorbing mechanism 23
In general, the variation in the absorption amount can be made smaller than that in the first shock absorbing mechanism 21 that uses caulking. As a result, it is possible to easily reduce the variation in the absorption amount in a predetermined shock absorbing stroke as a whole.

For example, the shock absorption characteristics of the steering apparatus 1 are as shown in the graph of FIG. FIG. 6 shows a change in the magnitude of the load (vertical axis) against a shock according to the stroke amount (horizontal axis).
The absorption amount of impact energy at T corresponds to the product of the load and the stroke amount (the area of the region surrounded by the lines in the graph). The load F1 applied by the first impact absorbing mechanism 21 and the load F2 applied by the second impact absorbing mechanism 22 are significantly reduced while the stroke amount after the collision is small. On the other hand, the load F3 applied by the third shock absorbing mechanism 23 increases with an increase in the stroke amount, and has a level almost equal to the load as a whole. As a result, the absorption amount E3 by the third shock absorbing mechanism 23 becomes significantly larger than the absorption amount E1 by the first shock absorbing mechanism 21 and the absorption amount E2 by the second shock absorbing mechanism 22, and the total absorption amount (E1 + E2 + E3). ).

On the other hand, the shock absorption characteristics of the conventional shock absorption steering device are as shown in the graph of FIG. 7, for example. The load F4 and the absorption amount E4 are based on the column contraction type shock absorbing mechanism described in the section of the prior art.
Further, the loads F5 and F6 and the absorption amounts E5 and E6 are due to two impact absorbing mechanisms that are substantially the same as the second and third impact absorbing mechanisms described in the embodiment of the present invention. The absorption amount of impact energy as a whole is
It is the sum of 5, E6. The loads F4 and F6 maintain a certain level within the range of a predetermined shock absorption stroke, and the absorption amounts E4 and E6 occupy a large proportion of the total absorption amount.

Further, the front side of the edge of the outward protrusion 29 is recessed one step lower than the outward protrusion 29, and the cylindrical surface 45 which is the recessed portion has a length corresponding to the shock absorbing stroke in the axial direction. Along the front of the relative movement. Since the cylindrical surface 45 escapes from all the inward projections 28 at the same time, the engagement between the projections 28 and 29 can be released all at once almost simultaneously, and as a result, the behavior at the time of collision can be stably obtained. In addition, when the protrusions 28 and 29 are engaged with each other, the engagement can be promptly released by a relative movement of a short distance. It is convenient to disengage each other at the same time.

It is also conceivable to allow a deviation in the timing at which the plurality of projections 28, 29 are disengaged from each other. In this case, the processing accuracy of the projections 28, 29 does not have to be increased, and the steering column 4 is not required. Can be made cheaper. Further, in the illustrated example, the cylindrical surface 45 is configured so that a gap is opened between the top surface 52 of the inward projection 28 facing the cylindrical surface 45 after the press fitting is released. In this case, the influence of friction between the jackets 10 and 11 can be minimized after the engagement between the protrusions 28 and 29 is released, which is preferable for suppressing the variation in the absorption amount. Further, the cylindrical surface 45 may be brought into sliding contact with the apexes 52 of the inward projections 28 facing each other after the press-fitting is released,
In this case, the cylindrical surface 45 can guide the inward projection 28,
It is preferable to smoothly slide the two jackets 10 and 11 relative to each other.

The inner circumference 31 of the outer jacket 10 has a cylindrical surface 38 and a plurality of, for example, 6 pieces projecting from the surface 38.
The above-mentioned inward projections 28 are provided. In addition, the outer jacket 30 has an outer periphery 30 on which a concave portion 3 is formed by caulking.
9 is formed, and the inward projection 2 described above is formed on the back surface of the recess 39.
8 is formed. The recess 39 is for forming the inward projection 28, and remains as a trace of pressing the caulking tool against the outer periphery 30. That is, the caulking tool is pressed against the outer circumference 30 of the outer jacket 10, whereby the outer circumference 30 is plastically deformed and recessed. As a result, the outer circumference 30
A concave portion 39 is formed in the inner surface of the concave portion 39, and an inward protrusion 28 is formed on the inner circumference 31 that is the back surface of the concave portion 39.

As a method of forming the inward projection 28,
A recess 39 may be formed in the outer jacket 10 while the two jackets 10 and 11 are fitted together. Further, the inner jacket 11 is fitted to the outer jacket 10 by forming the recess 39 in the outer jacket 10 before the inner jacket 11 is fitted.
May be fitted in a press-fitted state.

By providing the engaging positions of the projections 28 and 29 with each other at two locations and separating them in the axial direction,
11 can be connected with high rigidity. Such a plurality of inward projections 28 may be arranged along the axial direction and at the same position in the circumferential direction, but in this case, one of them is the front of the movement due to the relative movement at the time of collision. The outward protrusion 29 corresponding to the inward protrusion 28 may interfere with the other inward protrusion 28 that is behind the movement. Therefore, in the present embodiment, a pair of inward projections 28 corresponding to each other arranged in the axial direction are arranged so as to be displaced in the circumferential direction so that interference can be prevented.

For example, the inward projection 32 and the inward projection 33 form a pair corresponding to each other. Also, two inward projections 3
4, 35 correspond to each other. Further, the two inward projections 36 and 37 form a pair corresponding to each other. A pair of these inward projections 28 is formed on the inner circumference 3 of the outer jacket 10.
1 are arranged at equal intervals in the circumferential direction. The pair of inward projections 32 and 33 corresponding to each other are arranged relatively closer to each other in the circumferential direction than the other inward projections 28. The positions of the pair of inward projections 32 and 33 corresponding to each other are offset from each other in the circumferential direction. Thereby, interference can be prevented. The inward projections 28 of the other pairs than the pair of the inward projections 32 and 33 have substantially the same configuration.

The outer circumference 41 of the inner jacket 11 has the above-mentioned cylindrical surface 45 having a small diameter, and a plurality of long elongate axially bulged projections 29 projecting from this surface 45, for example, three. And bulging projections 42 to 44. The plurality of bulging projections 42 to 44 are arranged at a plurality of positions in the circumferential direction evenly corresponding to the plurality of pairs of the inward projections 28 forming a pair. A pair of inward projections 28 spaced apart in the axial direction of the outer jacket 10 are engaged with both axial end portions 48, 47 of the respective bulging projections 42-44. The positions of the pair of inward projections 28 are offset from each other in the circumferential direction (the circumferential direction of the positions corresponding to the inward projections 32 and 33 are shown by the arrow R), and the circumferential width of the bulging projections 42 to 44 is the inner jacket. The end portion 47 of the bulging projections 42 to 44 on the open end 49 side of 11 is wide (circumferential width L1) and the end portion 48 of the bulging projections 42 to 44 on the other end 50 side of the inner jacket 11.
Are narrowed (circumferential width L2, L2 <L1.) So that the pair of inward projections 28 and the bulging projections 42 to 44 are disengaged at substantially the same time during a collision. For example, the inward projection 33 is engaged with the end portion 47 of the bulging projection 42, and the bulging projection 4
The inward projection 32 engages with the end 48 of the second.

Further, when viewed from the axial direction, the pair of corresponding inward projections 32 and 33 are arranged so that a part thereof overlaps with each other. There is no problem because it does not rotate. Also,
The bulging protrusions 42 to 44 are axially intermediate portions 51 and can guide the inward protrusion 33 in the axial direction while restricting the inward protrusion 33 in the circumferential direction at the time of collision. As a result, it is possible to reliably prevent the inward projection 33 from colliding with the end portion 48 of the forward outward projection 29.

If the bulging projections 42 to 44 are as described above,
For example, the outward projections 29 having different circumferential widths at the one end 47 and the other end 48 can be easily formed by a simple method of bulging the pipe material of the inner jacket 11. Therefore,
The above-mentioned effect of preventing interference can be easily obtained.
Moreover, in the bulging formation, the outward projections 29 having partially different circumferential widths can be easily formed by using a generally inexpensive pipe material. In addition, the bulging projections 42 to 44 are attached to the inner jacket 1.
When reaching the open end 49 of No. 1, bulge formation is even easier.

Although a plurality of inward projections 28 and a plurality of outward projections 29 are provided in this embodiment, the present invention is not limited to this. For example, it is also conceivable to engage only a single inward projection 28 and a single outward projection 29 with one another. It is likewise conceivable that only one corresponding pair of inward projections 28 is provided. Further, the outward protrusions 29 and the inward protrusions 28 may correspond to each other on a one-to-one basis or a plurality of one-to-one basis. As the outward protrusion 29, the bulging protrusion 42 described above is used.
In addition to ~ 44, for example, a pipe material may be cut and processed, and in addition to a long one that is long in the axial direction, for example, one that has a circumferential width and an axial length that are substantially the same, A long one that is long in the direction is also conceivable.

The present invention may be applied to a steering device in which the outer jacket is at the front part, the inner jacket is at the rear part, and the inner jacket moves relative to the vehicle body at the time of a collision. Further, as the second and third shock absorbing mechanisms 22 and 23, other known shock absorbing mechanisms may be used in addition to those described above. Further, the second and third shock absorbing mechanisms 22 and 23 are omitted and only the first shock absorbing mechanism 21 is provided by utilizing a known shock absorbing mechanism outside the steering device such as an airbag or a seat belt. It is also possible.

Besides, various modifications can be made within the scope of the claims of the present invention.

[Brief description of drawings]

FIG. 1 is a side view of a schematic configuration of a shock absorbing steering device according to an embodiment of the present invention.

2 is a partial cross-sectional side view of a main part of the shock absorbing steering device of FIG. 1, showing a state before a collision.

3 is a partial cross-sectional side view of the main part shown in FIG. 2, showing a state after a collision.

4 is a sectional view taken along line AA of FIG.

5 is an exploded perspective view of the inner jacket and the outer jacket of FIG.

6 is a graph schematically showing the impact absorption characteristics of the impact absorption steering device of FIG. 1, in which the vertical axis represents the load magnitude and the horizontal axis represents the stroke amount of relative sliding between the jackets to absorb the impact. The load which resists the impact of each mechanism is indicated by the length along the vertical axis between the lines in the graph, and the change in the load is shown from the stroke amount of 0 to the impact absorption stroke amount ST.
It is illustrated until it becomes.

FIG. 7 is a graph showing the impact absorption characteristics of a conventional impact absorption steering device as in FIG.

[Explanation of symbols]

1 Shock absorption steering device 3 steering shaft 4 steering column 10 outer jacket 11 inner jacket 28 Inward projection 29 outward protrusion 32, 33 a pair of inward projections 34,35 a pair of inward projections 36,37 a pair of inward projections 42-44 Swelling protrusion (outward protrusion) 47 Axial end of bulging protrusion (open end side) 48 Axial end of bulging protrusion (other end side) 49 Open end of inner jacket 50 The other end of the inner jacket L1, L2 Circumferential width of bulging protrusion S axis direction R circumferential direction

Claims (3)

[Claims] 1. A steering column that rotatably supports a steering shaft has a cylindrical outer jacket and inner jacket that are fitted to each other, and both jackets relatively slide in the axial direction at the time of collision to absorb the shock. In the shock absorbing steering device, both jackets are press-fitted by engaging the inward projections of the outer jacket and the outer projections of the inner jacket that are formed by caulking, and the two jackets are slid together during a collision. A shock absorbing steering device characterized in that the press-fitted state of both jackets is released by disengaging the engagement between the inward protrusion and the outward protrusion. 2. The shock absorbing steering device according to claim 1, wherein the inward projections include at least a pair of inward projections that are separated from each other in the axial direction of the outer jacket, and the positions of the pair of inward projections corresponding to each other are circumferential. A shock absorbing steering device characterized by being displaced from each other. 3. The shock absorbing steering device according to claim 1, wherein the outward projection of the inner jacket includes a long bulging projection that is bulged long in the axial direction, and the bulging projection has an axial direction. A pair of inward projections spaced apart from each other in the axial direction of the outer jacket are engaged with both ends of the inner jacket, the positions of the pair of inward projections are circumferentially displaced from each other, and the circumferential width of the bulging projection is equal to the open end side of the inner jacket. The shock absorbing steering device is characterized in that the pair of inward projections and the bulging projections are disengaged at substantially the same time at the time of a collision by widening at the end of the pair and narrowing at the end on the other end side.