JP4158596B2 - Steering device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steering device configured to absorb the impact energy of a secondary collision applied to a steering member at the time of a vehicle collision by shortening a cylindrical steering column supporting the steering shaft in the axial direction.
[0002]
[Prior art]
In steering a vehicle, a steering torque applied to a steering wheel (steering member) disposed inside the passenger compartment is distributed outside the passenger compartment to steer steering wheels (generally, left and right front wheels). To the steering mechanism. A steering device for performing such steering is provided with a steering wheel attached to an upper end portion of a steering shaft that is rotatably supported around a shaft inside a passenger compartment, and a lower end portion of the steering shaft is provided as a steering mechanism. It is connected and configured.
[0003]
In such a steering device, the steering shaft can be rotated for the purpose of reducing the damage of the driver who collides with the steering wheel (secondary collision) due to the inertial effect in the traveling direction at the frontal collision of the vehicle. The supporting steering column is configured to include an inner cylinder and an outer cylinder that are fitted inside and outside for an appropriate length and can be shortened in the axial length direction, and the secondary collision described above due to the frictional resistance when these are shortened. There is one configured as an impact-absorbing steering device that absorbs impact energy at the time (see, for example, Patent Document 1).
[0004]
Conventionally, the provision of frictional resistance when the inner cylinder and the outer cylinder are shortened has been realized in various configurations. In the steering apparatus disclosed in Patent Document 1, the outer wall of the outer cylinder is caulked at two positions separated by an appropriate length in the axial direction, and a plurality of resistance protrusions projecting inward are provided on the inner circumferential surface of each position. Thus, these protrusions are brought into pressure contact with the outer peripheral surface of the inner cylinder, and friction resistance is given by sliding of the pressure contact portion, and the object can be achieved with a simple structure.
[0005]
[Patent Document 1]
JP-A-2002-293249 [0006]
[Problems to be solved by the invention]
Now, in the shock absorption type steering device configured as described above, the driver who collides with the steering wheel is subjected to frictional resistance between the inner cylinder and the outer cylinder as a reaction force, thereby reducing the driver's damage. In order to achieve the initial purpose of doing this, it is important that the inner cylinder and the outer cylinder are shortened under a substantially constant resistance over the entire length of the shortening stroke.
[0007]
However, in the steering device described in Patent Document 1, it is difficult to manage the protruding amount of the resistance projection formed by caulking of the outer cylinder with high accuracy, and the pressure contact load with the inner cylinder varies, resulting in impact. In some cases, desired frictional resistance for absorption cannot be obtained. This difficulty can be solved by adjusting the protruding amount of the resistance projection before fitting with the inner cylinder, but this adjustment requires a second caulking process using caulking equipment. There is a problem that the product cost increases due to the increase.
[0008]
Therefore, conventionally, a plurality of inner cylinders having different outer diameters within a predetermined tolerance range are prepared, and the inner cylinder has an outer diameter that matches the actual size of the resistance projection on the inner surface of the outer cylinder to be assembled. There is a problem that the labor of assembling increases.
[0009]
On the other hand, a torsional force around the shaft is applied to the steering column due to the reaction force caused by the rotation of the steering shaft supported inside, and in particular, a column assist type equipped with a steering assist motor in the middle of the steering column. When configured as an electric power steering device, a large torsional force is applied to the steering column by the action of the rotational force of the motor transmitted to the steering shaft under deceleration.
[0010]
When such a twisting force is applied, in the steering device disclosed in Patent Document 1, a slight circumferential slip (stick slip) occurs in the fitting portion of the inner cylinder and the outer cylinder constituting the steering column. Sometimes. This slip does not adversely affect the rotation of the steering shaft inside the steering column and the steering performed by this rotation, but the noise generated by the slip propagates into the passenger compartment, and the driver or passenger May be misunderstood that some trouble such as failure or damage has occurred.
[0011]
The present invention has been made in view of such circumstances, and it is possible to easily adjust the frictional resistance between the inner cylinder and the outer cylinder constituting the steering column, thereby reliably realizing a desired shock absorbing performance. An object of the present invention is to provide a steering apparatus that can cause the outer cylinder and the inner cylinder constituting the steering column to slide in the circumferential direction without generating abnormal noise. .
[0012]
[Means for Solving the Problems]
A steering apparatus according to a first aspect of the present invention includes an inner cylinder and an outer cylinder fitted with a steering shaft for transmitting a steering torque applied to a steering member to a steering mechanism over an appropriate length. In the steering device that absorbs the impact energy of the secondary collision applied to the steering member at the time of a vehicle collision by shortening in the axial direction that occurs under a predetermined resistance between the inner cylinder and the outer cylinder, By knurling the outer peripheral surface of the inner cylinder or the inner peripheral surface of the outer cylinder, a plurality of protrusions formed from the respective surfaces are adjusted over the entire circumference of the outer peripheral surface or the inner peripheral surface. Protruding portions are provided, and these protruding portions are pressed against the inner peripheral surface of the outer cylinder or the outer peripheral surface of the inner cylinder.
[0013]
In the present invention, the inner cylinder and the outer cylinder constituting the steering column are brought into pressure contact with a plurality of convex portions formed by knurling on one fitting peripheral surface by the action of an impact force accompanying a secondary collision. The impact energy of the secondary collision is absorbed by the frictional resistance between these convex portions. The frictional resistance in this case can be easily adjusted by adjusting the height of the convex portion by selecting the knurling used for processing and the pressing force, thereby realizing the desired shock absorption performance with high accuracy. be able to. The magnitude of the frictional resistance can also be adjusted by increasing or decreasing the knurling range in the axial direction and circumferential direction.
[0014]
A steering device according to a second aspect of the present invention includes a groove formed on the outer peripheral surface of the inner cylinder or the inner peripheral surface of the outer cylinder by the knurling, and the inner peripheral surface of the outer cylinder or the outer periphery of the inner cylinder. A lubricant is held between the surface and the surface.
[0015]
In the present invention, due to the action of torsional force applied to the steering column, the inner cylinder and the outer cylinder constituting the steering column have a groove formed by knurling and the inner peripheral surface of the outer cylinder or the outer peripheral surface of the inner cylinder. Slip under the action of a lubricant held between the two, and the generation of sound accompanying this slip is reduced.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof. FIG. 1 is a schematic diagram showing an overall configuration of a steering apparatus according to the present invention.
[0017]
In the figure, reference numeral 1 denotes a steering shaft. The steering shaft 1 is coaxially supported inside a cylindrical steering column 2 and is fixed to a middle portion and one end portion of the steering column 2 respectively. The lower bracket 21 and the lower bracket 21 are supported inside the passenger compartment in an inclined posture with the lower bracket 21 side facing forward and downward (lower left in the figure).
[0018]
A steering wheel 10 as a steering member is fitted and fixed to the upper end portion of the steering shaft 1 protruding above the steering column 2 so as to face a driver (not shown) in the vehicle interior, and the steering wheel also protrudes downward. A lower end portion of the shaft 1 is connected to an input shaft 70 of the steering mechanism 7 via an intermediate shaft 6 having universal joints 60 and 60 at both ends. With the above configuration, the steering torque applied to the steering wheel 10 for steering is transmitted to the input shaft 70 of the steering mechanism 7 via the steering shaft 1 and the intermediate shaft 6, and the steering is performed by the operation of the steering mechanism 7. Is executed.
[0019]
The steering device shown in FIG. 1 includes a steering assist motor 23 attached in the vicinity of the lower end of the steering column 2, and a torque sensor 24 in the steering column 2 above the motor 23. The steering torque applied to the steering wheel 10 is detected by the torque sensor 24, and the rotational force of the motor 23 driven based on the detected torque is transmitted to the steering shaft 1 in the steering column 2 to perform the steering performed as described above. However, the characteristic configuration of the steering device according to the present invention described below is a manual type that allows steering by only the steering torque applied to the steering wheel 10 by the driver. The hydraulic system can be applied to a steering device and is attached to the steering mechanism 7. The force generated Sunda is also applicable to a hydraulic power steering device for assisting the steering.
[0020]
In the steering device according to the present invention, the upper half of the steering column 2 that is continuous with the upper position of the built-in portion of the torque sensor 24 is fitted inside and outside over an appropriate length and combined so as to be relatively movable in the axial direction. The outer cylinder 3 and the inner cylinder 4 are provided. The upper bracket 20 that supports the upper part of the steering column 2 to the vehicle body is fixed to the middle part of the outer cylinder 3, and the capsule 22 is left on the vehicle body by the action of a force exceeding a predetermined limit applied to the steering column 2 downward. It is configured as a well-known breakaway bracket that is released downward.
[0021]
2 is a longitudinal sectional view of a fitting portion of the outer cylinder 3 and the inner cylinder 4 constituting the steering column 2, and FIG. 3 is an exploded perspective view of the fitting portion. The outer cylinder 3 and the inner cylinder 4 are both thin cylindrical bodies, and the inner cylinder 4 located on the lower side is provided on the outer peripheral surface near the upper end portion on the fitting side to the outer cylinder 3 over the entire circumference. Knurled portions 40, 40... Formed by knurling are formed at a plurality of locations in the axial direction. The outer cylinder 3 is fitted so as to cover the entire formation range of the knurled portions 40, 40... And the inner peripheral surface of the outer cylinder 3 is in contact with the knurled portions 40, 40.
[0022]
FIG. 4 is an explanatory view showing the surface properties of the knurled portion 40 in an enlarged manner. Knurling is a known processing method in which a knurl having a predetermined concavo-convex pattern on the outer surface is pressed against a processing surface, and the concavo-convex pattern is transferred to the processing surface. In the knurl processing portion 40 subjected to such knurl processing, a large number of convex portions 4a, 4a,... Protruding from the original outer peripheral surface of the inner cylinder 4 are arranged at positions corresponding to the concave pattern of the used knurl. It is formed. As shown by a two-dot chain line in FIG. 4, the inner peripheral surface of the outer cylinder 3 fitted on the inner cylinder 4 is in pressure contact with the convex portions 4a, 4a,.
[0023]
The outer cylinder 3 and the inner cylinder 4 fitted in this way are affected by the external force applied in the axial direction, and the convex portions 4a, 4a,... Shorten under frictional resistance with the surface. Here, the height of the convex parts 4a, 4a ... in the knurled parts 40, 40 ... can be freely adjusted by selecting the knurling used for processing and the magnitude of the pressing force of the knurling. The size of the frictional resistance at the time of shortening 4 can be easily adjusted without requiring labor.
[0024]
The frictional resistance of the outer cylinder 3 and the inner cylinder 4 can be increased or decreased by changing the number of the knurling parts 40, 40... Arranged in parallel or the length of each knurling part 40, 40. In addition, the frictional resistance can be adjusted easily and with high accuracy. Furthermore, the form of formation may be different for each of the plurality of knurled portions 40, 40,.
[0025]
2 and 3, the configuration in which the knurled knurls 40, 40... Are provided on the outer circumferential surface of the inner cylinder 4 is described. It is also possible to form knurled portions of other forms such as flat and oblique.
[0026]
In the steering column 2 including the outer cylinder 3 and the inner cylinder 4 fitted as described above, the driver collides with the steering wheel 10 due to inertia in the traveling direction of the vehicle (secondary collision) at the time of frontal collision of the vehicle. When applied, an impact force is applied downward in the axial direction. At this time, the upper bracket 20 configured as a breakaway bracket as described above is detached from the vehicle body, and the outer cylinder 3 released from the restraint by the upper bracket 20 is fitted into the inner cylinder 4 by the action of the impact force. The steering column 2 is shortened by relative movement in an increasing direction. As described above, this shortening is performed under the frictional resistance between the convex portions 4a, 4a ... of the knurled portions 40, 40 ... provided on the outer peripheral surface of the inner cylinder 4 and the inner peripheral surface of the outer cylinder 3. 1 is absorbed between the shortened strokes indicated as S in FIG.
[0027]
During this time, the frictional resistance between the outer cylinder 3 and the inner cylinder 4 is applied to the driver who has collided with the steering wheel 10 as a reaction force. As described above, this frictional resistance can be managed with high accuracy by adjusting the height of the plurality of convex portions 4a, 4a ... of the knurled portions 40, 40 ... Protected without heavy damage by sustained load of force. As described above, the height of the convex portions 4a, 4a,... Can be easily adjusted (tuned) without requiring much labor, and a desired shock absorbing performance can be realized with high accuracy.
[0028]
Grooves are respectively formed between the plurality of convex portions 4a, 4a ... of the knurled portions 40, 40 ..., and these grooves form a minute space between the outer peripheral surface of the outer cylinder 3. In these spaces, when the inner cylinder 4 is press-fitted into the outer cylinder 3, a lubricant such as grease supplied for lubrication between the two is held in a confined state.
[0029]
The steering column 2 including the outer cylinder 3 and the inner cylinder 4 has a shaft caused by the reaction force accompanying the rotation of the steering shaft 1 supported therein and the rotational force transmitted from the steering assisting motor 23 to the steering shaft 1. The twisting force around is added. When a twisting force is applied in this way, slip occurs between the outer cylinder 3 and the inner cylinder 4, and this slip is caused by the lubricant held in the grooves of the knurled portions 40, 40. There is no possibility that a driver or a passenger in the passenger compartment is misunderstood that a malfunction has occurred without causing abnormal noise under the action.
[0030]
【The invention's effect】
As described in detail above, in the steering device according to the first aspect of the present invention, the shortening of the steering column caused by the impact absorption at the time of the secondary collision is reduced between the inner cylinder and the outer cylinder constituting the steering column. It can be performed under the action of a friction resistance force that can be easily adjusted, achieves desired shock absorption performance with high accuracy, and is useful for ensuring the safety of the driver.
[0031]
In the steering device according to the second aspect of the present invention, when a twisting force about the axis is applied to the steering column, the inner cylinder and the outer cylinder constituting the steering column are held in the groove of the knurled portion. The present invention has an excellent effect, for example, the possibility of being misunderstood by the driver when slipping or malfunctioning is caused without any noise due to the action of the lubricant.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an overall configuration of a steering apparatus according to the present invention.
FIG. 2 is a longitudinal sectional view of an outer cylinder and a fitting part of an inner cylinder constituting a steering column.
FIG. 3 is an exploded perspective view of a fitting portion of an outer cylinder and an inner cylinder constituting a steering column.
FIG. 4 is an explanatory diagram showing an enlarged surface property of a knurled portion.
[Explanation of symbols]
1 Steering shaft 2 Steering column 3 Outer cylinder 4 Inner cylinder 6 Steering mechanism
10 Steering wheel (steering member)
40 Knurling section
4a Convex

Claims (2)

A steering shaft for transmitting a steering torque applied to the steering member to the steering mechanism is supported inside a steering column having an inner cylinder and an outer cylinder fitted over an appropriate length, and the steering is performed in the event of a vehicle collision. In the steering device that absorbs the impact energy of the secondary collision applied to the member by shortening in the axial length direction generated under a predetermined resistance between the inner cylinder and the outer cylinder,
By knurling the outer peripheral surface of the inner cylinder or the inner peripheral surface of the outer cylinder , a plurality of protrusions formed from the respective surfaces are adjusted over the entire circumference of the outer peripheral surface or the inner peripheral surface. It includes a convex portion, a steering device in which these protrusions and wherein the Ah Turkey by pressure contact with the outer peripheral surface of the inner peripheral surface or the inner cylinder of the outer cylinder. A lubricant is held between the groove formed in the outer peripheral surface of the inner cylinder or the inner peripheral surface of the outer cylinder by the knurling and the inner peripheral surface of the outer cylinder or the outer peripheral surface of the inner cylinder. The steering apparatus according to claim 1.

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