JP2006111059A - Shock absorbing type steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shock absorbing type steering device capable of obtaining shock absorbing load with a little variation. <P>SOLUTION: The shock absorbing type steering device has an internal cylinder 21 and an external cylinder 22 where a column tube 23 of a steering column 20 is fitted by press fitting. A projection 33 formed on the inner peripheral surface 22b of the external cylinder 22 is pressurized to the outer peripheral surface 21a of the internal cylinder 21 by caulking. A groove 35 for storing and holding lubricating grease is provided on a contact part 33a of the projection 33 relative to the internal cylinder 21. A part between contact parts 33a, 21b with the internal cylinder 21 is lubricated by the grease supplied from the groove and projection 35. Even if a slight vibration is generated where the internal cylinder 21 and the external cylinder 22 are twisted by the reaction force torque of an electric motor in the rotating direction, an abnormal wear or welding is not generated on the contact parts 33a, 21b. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an impact absorption type steering apparatus that absorbs an impact at the time of a vehicle collision.

A steering column that rotatably supports the steering shaft is included, and the steering column includes an inner cylinder and an outer cylinder that are fitted in a press-fit state, and absorbs shock by the relative sliding of the inner cylinder and the outer cylinder at the time of collision. There is a shock absorbing steering device.
Usually, the relative movement in the axial direction of both cylinders at normal times is prevented by pressurizing the outer circumferential surface of the inner cylinder by a protrusion formed on the inner circumferential surface of the outer cylinder (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2003-2211

By the way, there is a column assist type electric power steering apparatus that obtains a steering assist force by an electric motor attached to a steering column.
In this type of electric power steering apparatus, the inner cylinder and the outer cylinder vibrate slightly in the rotational direction due to the influence of the driving reaction force of the electric motor. As a result, there is a problem that abnormal wear occurs or welding occurs in the protrusion of the outer cylinder and the contact portion of the inner cylinder. When abnormal wear or welding occurs, there is a possibility that a shock absorbing load having a desired size cannot be achieved.

Problems such as abnormal wear of the contact portion due to slight vibrations also exist in electric power steering devices and manual steering devices other than the column assist type.
The present invention has been made in view of the above problems, and an object of the present invention is to provide an impact-absorbing steering apparatus that can obtain an impact-absorbing load with little variation.

  In order to achieve the above object, the present invention includes a steering column that rotatably supports a steering shaft, the steering column including an inner cylinder and an outer cylinder that are fitted to each other. In the shock absorbing type steering device that absorbs an impact by sliding, a protrusion is formed on at least one of the outer peripheral surface of the inner cylinder and the inner peripheral surface of the outer cylinder, and a pressure is applied to the other. A lubricant holding recess for holding is formed.

In the present invention, even if the steering column is subjected to slight vibration during normal use, abnormal wear or welding does not occur at the contact portion between the projection and the other cylinder. As a result, a stable shock absorbing load can be obtained during shock absorption.
In the present invention, the lubricant retaining recess may include a plurality of grooves extending in the same direction. In this case, the groove can be easily formed by pressing or cutting.

In the present invention, a solid lubricant film may be formed on the other of the outer peripheral surface of the inner cylinder and the inner peripheral surface of the outer cylinder. In this case, it is possible to reliably prevent the occurrence of abnormal wear or welding at the contact portion between the protrusion and the other cylinder.
In the present invention, a steering assist force by an electric motor attached to the steering column may be obtained. In a so-called column-type electric power steering device, a rotational reaction occurs between the inner cylinder and the outer cylinder due to the driving reaction force of the electric motor, which causes abnormal wear and welding at the contact portion between the protrusion and the other cylinder. It tends to be easy. In the column-type electric power steering apparatus having such a tendency, a particularly remarkable effect that the occurrence of the abnormal wear and welding can be surely prevented can be exhibited.

A preferred embodiment of the present invention will be described with reference to the accompanying drawings.
As shown in FIG. 1, an impact absorption type steering apparatus 1 according to an embodiment of the present invention is configured as a column assist type electric power steering apparatus. Specifically, the shock absorbing steering device 1 includes a steering shaft 3 connected to a steering member 2 such as a steering wheel, an intermediate shaft 5 connected to the steering shaft 3 via a universal joint 4, and an intermediate shaft. As a steered shaft that extends in the left-right direction of the automobile, has a pinion shaft 7 connected to 5 through a universal joint 6 and rack teeth 8a that mesh with pinion teeth 7a provided in the vicinity of the end of the pinion shaft 7. And a rack bar 8. The pinion shaft 7 and the rack bar 8 constitute a steering mechanism A including a rack and pinion mechanism.

The rack bar 8 is supported in a housing 9 fixed to the vehicle body so as to be capable of linear reciprocation through a plurality of bearings (not shown). Both end portions of the rack bar 8 protrude to both sides of the housing 9, and tie rods 10 are coupled to the respective end portions. Each tie rod 10 is connected to a corresponding wheel 11 via a corresponding knuckle arm (not shown).
When the steering member 2 is operated and the steering shaft 3 is rotated, this rotation is converted into a linear motion of the rack bar 8 along the left-right direction of the automobile by the pinion teeth 7a and the rack teeth 8a. Thereby, steering of the wheel 11 is achieved.

  The steering shaft 3 is divided into an input shaft 31 connected to the steering member 2 and an output shaft 32 connected to the pinion shaft 7. These input and output shafts 31, 32 are on the same axis via the torsion bar 12. They are connected to each other so as to be relatively rotatable. The input shaft 31 includes, for example, a shaft 31a and a cylinder 31b that are serrated and connected to each other, and can contract when an impact load is applied to the steering member 2 due to a secondary collision or the like.

  A torque sensor 13 is provided for detecting a steering torque based on a relative rotational displacement amount between the input and output shafts 31 and 32 via the torsion bar 12, and the torque detection result of the torque sensor 13 is an ECU (Electronic Control Unit: electronic). Control unit) 14. The ECU 14 drives and controls the steering assisting electric motor 16 via the drive circuit 15 based on a torque detection result or a vehicle speed detection result given from a vehicle speed sensor (not shown). The output rotation of the electric motor 16 is decelerated via the speed reducer 17 and transmitted to the output shaft 32 of the steering shaft 3, and further converted into a linear motion of the rack bar 8 via the pinion shaft 7, thereby assisting steering. .

The speed reducer 17 is a worm shaft 18 as a drive gear that is rotationally driven by the electric motor 16, and a worm wheel as a driven gear that meshes with the worm shaft 18 and is connected to the output shaft 32 of the steering shaft 3 so as to be integrally rotatable. 19 is provided.
The shock absorbing steering device 1 includes a steering column 20 that rotatably supports the steering shaft 3 through the inside. The steering column 20 includes a column tube 23 including an inner cylinder 21 serving as a lower jacket and an outer cylinder 22 serving as an upper jacket, and a column housing 24 coupled to one end of the column tube 23.

The column housing 24 accommodates the speed reducer 17 and the torque sensor 13 described above, and the housing of the electric motor 16 is fixed.
The inner cylinder 21 and the outer cylinder 22 slide relative to each other at the time of collision to absorb impact energy. An upper bracket 25 is fixed to the outer tube 22 as an upper tube. The upper bracket 25 is fixed to a vehicle body side bracket 28 held by the vehicle body 27 via a connecting member 26. The connecting member 26 includes a breakable pin made of a synthetic resin for allowing the vehicle body side bracket 28 to be detached from the vehicle body 27 at the time of a secondary collision. Further, the inner cylinder 21 as a lower tube is fixed to a vehicle body side bracket 29 fixed to the vehicle body 27 by using a lower bracket 30.

A plurality of protrusions 33 are formed on the inner peripheral surface of the outer cylinder 22 as an upper jacket, and these protrusions 33 are caulked to the outer peripheral surface 21a of the inner cylinder 21 as a lower jacket and are pressurized. Thereby, the relative movement of the inner cylinder 21 and the outer cylinder 22 is suppressed.
With reference to FIG. 2, a plurality of protrusions 33 are provided on the inner peripheral surface 22 b of the outer cylinder 22 in the circumferential direction by forming a recess 34 on the outer peripheral surface 22 a of the outer cylinder 22. As illustrated, a plurality of rows of protrusions 33 may be provided at a distance in the axial direction of the outer cylinder 22.

  The protrusion 33 can be formed by expanding the inner peripheral surface 22b of the outer cylinder 22 by pressurizing the outer peripheral surface 22a of the outer cylinder 22 by pressing. With reference to FIG. 3 and FIG. 4, a groove 35 as one or a plurality of lubricant retaining recesses is formed in the contact portion 33 a of the protrusion 33 with respect to the contact portion 21 b of the outer peripheral surface 21 a of the inner cylinder 21. Lubricating grease is contained and held. If it is the groove | channel 35, it can form easily by press molding or cutting.

When a plurality of grooves 35 are formed, these grooves 35 preferably extend in the same direction, but the direction is not particularly limited.
According to the present embodiment, even if the steering column 20 receives slight vibration during normal use, the lubricating grease is provided from the groove 35 between the contact portion 33a of the protrusion 33 and the contact portion 21b of the outer peripheral surface 21a of the inner cylinder 21. Therefore, the contact portions 33a and 21b are not abnormally worn and the contact portions 33a and 21b are not welded to each other. As a result, a stable shock absorbing load can be obtained when the contact portion 33a of the projection 33 slides with respect to the outer peripheral surface 21a of the inner cylinder 21 during shock absorption.

  In particular, in the combination with the column assist type electric power steering as in the present embodiment, a remarkable effect can be achieved in preventing the occurrence of the abnormal wear and welding. This is because in the column assist type electric power steering apparatus, during normal use, a rotational reaction occurs between the inner cylinder 21 and the outer cylinder 22 due to the driving reaction force of the electric motor 16, and as a result, the above-mentioned abnormality This is because wear and welding tend to occur easily, but even in the column-type electric power steering apparatus having such a tendency, abnormal wear and welding can be reliably prevented.

As shown in FIG. 5, if the outer peripheral surface 21a of the inner cylinder 21 is coated with a solid lubricant film 36 such as molybdenum disulfide, PTFE, FEP, etc., abnormalities will occur at both contact portions 33a, 21b. Wear and welding can be prevented more reliably.
Further, the same effect can be obtained by coating the outer peripheral surface 21a of the inner periphery 21 with a coating by cationic coating instead of the coating 36 of the solid lubricant.

The present invention is not limited to the above-described embodiment, and a large number of dimples 37 that are dimple-processed as shown in FIG.
The protrusion 33 having the lubricant retaining recess may be formed on at least one of the outer peripheral surface 21 a of the inner cylinder 21 and the inner peripheral surface 22 b of the outer cylinder 22. The solid lubricant film 36 and the cation-coated film may be coated on the other cylinder with which the protrusion 33 contacts.

FIG. 1 is a schematic diagram showing a schematic configuration of an impact absorption type steering apparatus according to an embodiment of the present invention. It is a disassembled perspective view of the inner cylinder and outer cylinder which comprise the column tube of a steering column. It is a partially broken perspective view of the principal part of an outer cylinder. It is an expanded sectional view of an outer cylinder and an inner cylinder. It is sectional drawing of the principal part of the inner cylinder of another embodiment of this invention. It is a top view of the protrusion of another embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shock absorption type steering device 2 Steering member 3 Steering shaft 5 Intermediate shaft 7 Pinion shaft 8 Rack bar 11 Wheel 12 Torsion bar 13 Torque sensor 14 ECU
16 Electric motor 17 Reducer 20 Steering column 21 Inner cylinder 21a Outer peripheral surface 21b Contact portion 22 Outer cylinder 22a Outer peripheral surface 22b Inner peripheral surface 23 Column tube 24 Column housing 31 Input shaft 32 Output shaft 33 Protrusion 33a Contact portion 35 Groove (Lubricant) Holding recess)
36 Solid lubricant film 37 Dimple (lubricant holding recess)

Claims (4)

A shock-absorbing type steering that includes a steering column that rotatably supports a steering shaft, includes an inner cylinder and an outer cylinder that are fitted to each other, and absorbs an impact by the relative sliding of the inner cylinder and the outer cylinder at the time of a collision. In the device
A protrusion is formed on at least one of the outer peripheral surface of the inner cylinder and the inner peripheral surface of the outer cylinder and is pressurized on the other, and a lubricant holding recess for holding the lubricant is formed on the surface of the protrusion. Shock absorbing steering device.   2. The shock absorbing steering device according to claim 1, wherein the lubricant retaining recess includes a plurality of grooves extending in the same direction.   3. The shock absorbing steering device according to claim 1, wherein a coating film of a solid lubricant is formed on the other of the outer peripheral surface of the inner cylinder and the inner peripheral surface of the outer cylinder.   4. The shock absorbing type steering apparatus according to claim 1, 2, or 3, wherein a steering assist force is obtained by an electric motor attached to a steering column.

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