Outer column for telescopic steering device and telescopic steering device

An upper surface of a front portion of an outer column is provided with a slit having a substantial T shape as seen from a radial direction and a pair of sandwiched portions. In a rear end side portion of an outer surface of the sandwiched portion, a dented portion is formed to be dented inward in a width direction at a lower half portion thereof. Accordingly, a distance from the position of a force which acts on the sandwiched portions according to an operation on an adjustment lever to a position of a main outer column body which is a fulcrum of elastic deformation becomes longer. Therefore, a structure capable of reducing change of a force necessary for operating the adjustment lever and stably fitting and holding an inner column regardless of the position of a steering wheel in a front-rear direction is implemented.

TECHNICAL FIELD

The present invention relates to an improvement on a telescopic steering device which can adjust a position of a steering wheel in a front-rear direction and on an outer column to configure the telescopic steering device.

BACKGROUND ART

As a steering device for providing a steering angle to steering wheels (generally, front wheels, except for special vehicles such as forklifts), for example, a structure as shown inFIG. 9is widely known. In this steering device, a steering shaft3is rotatably supported on an inner side of a cylindrical steering column2which is supported on a vehicle body1. A steering wheel4is fixed to a rear end portion of the steering shaft3protruding toward the rear side from a rear end opening of the steering column2. If the steering wheel4is rotated, this rotation is transmitted to an input shaft8of a steering gear unit7through the steering shaft3, a universal joint5a, an intermediate shaft6and a universal joint5b. If the input device8rotates, a pair of tie rods9,9provided on both sides of the steering gear unit7are pushed and pulled, whereby a steering angle according to the operation amount of the steering wheel4is provided to a pair of left and right steering wheels. In this specification and claims, a front-rear direction, a width direction, and a vertical direction refers to a front-rear direction, a width direction, and a vertical direction of a vehicle body on which a telescopic steering device is mounted. That is, inFIG. 9, with respect to the steering column2, the steering gear unit7is positioned on the front side, and the steering wheel4is positioned on the rear side.

In this steering device, there has been known a telescopic mechanism for adjusting the position of the steering wheel in the front-rear direction according to the physique or driving position of a driver. In order to configure this telescopic mechanism, a rear portion of an inner column10provided on a front side is fitted into a front portion of an outer column11provided on a rear side so as to be relatively displaceable in an axial direction, whereby the steering column2is configured such that its total length can increase or decrease in a telescopic manner. Also, an outer tube12and an inner shaft13are assembled by spline engagement or the like, whereby the steering shaft3is configured to be able to transmit torque and able to be extended and contracted.

The example shown inFIG. 9incorporates a tilt mechanism capable of adjusting a vertical position of the steering wheel4. Further, this example incorporates an electric power steering device which uses an electric motor14as an auxiliary power source to reduce a force necessary for operating the steering wheel4. To this end, on the front end portion of the steering column2(the inner column10), a housing15including a worm reducer and the like configuring the electric power steering device is provided, and the housing15is supported on the vehicle body1to be able to swing around a horizontal shaft16. On a supporting bracket17supported at a different location of the vehicle body1, a column-side bracket18fixed to a portion of the steering column2(the outer column11) is supported to be displaceable in the front-rear direction and the vertical direction.

In the tilt mechanism and the telescopic mechanism except for an electric type, they are required to be switchable between a state where they can adjust the position of the steering column2and a state where they can hold the steering column at an adjusted position. An example of a conventional structure of a position adjusting mechanism will be described with reference toFIG. 10in addition toFIG. 9. In order to make it possible to elastically expand or contract an inner diameter of the front end portion of the outer column11, a slit19is formed on a lower surface of the outer column11from the front end portion to a center side portion to be long in the axial direction. A pair of sandwiched portions20,20configuring the column-side bracket18are provided on the outer column11at positions interposing the slit19therebetween in the width direction. At positions of the sandwiched portions20,20which match with each other, front-rear long holes21,21are formed long in the axial direction of the outer column11. In a pair of supporting plate members22,22which configure the supporting bracket17and sandwiches the sandwiched portions20,20from both sides in the width direction and are parallel to each other, vertical long holes23,23are formed to have a partial arc shape about the horizontal shaft16. Here, the vertical direction ofFIG. 10corresponds to the vertical direction of the vehicle body. An adjustment rod24is inserted through the long holes21,23.

An expansion/contraction mechanism incorporated in the adjustment rod24makes it possible to expand or contract an interval between the supporting plate members22,22, thereby making it possible to adjust the position of the outer column11in the vertical direction and the front-rear direction and to hold the outer column11at the adjusted position. In order to configure the expansion/contraction mechanism, on a portion of a base end portion of the adjustment rod24protruding from an outer surface of one supporting plate member22(the left one ofFIG. 10) of the supporting plate members22,22, a base end portion of an adjustment lever25is fixed, and a cam device26is provided between the outer surface of the one supporting plate member22and the adjustment lever25. The cam device26is expanded or contracted in the axial direction based on a relative displacement between a drive-side cam27and a driven-side cam28, and the driven-side cam28is engaged with the vertical long hole23formed in the one supporting plate member22to be displaceable only along the vertical long hole23(with rotation thereof being restricted). The drive-side cam27is configured to be rotatable together with the adjustment rod24by the adjustment lever25. On a portion of a tip end portion of the adjustment rod24protruding from the outer surface of the other supporting plate member22(the right one ofFIG. 10) of the supporting plate members22,22, a nut29is fixed, and a thrust bearing30and a pressing plate31are provided between the other supporting plate member22and the nut29. On an inner surface of the pressing plate31, an engaging piece32is provided, and the engaging piece32is engaged with the vertical long hole23formed in the other supporting plate member22to be displaceable only along that vertically long hole23.

In order to adjust the position of the steering wheel4, the adjustment lever25is rotated toward a predetermined direction (downward), whereby the drive-side cam27is rotated such that the dimension of the cam device26in the axial direction decreases. As a result, the interval between the inner surfaces of the driven-side cam28and the nut29facing each other is expanded, whereby the force of the supporting plate members22,22pressing the sandwiched portions20,20is released. At the same time, the inner diameter of the fitting portion which is the front portion of the outer column11and internally fitted with the rear portion of the inner column10is elastically expanded, whereby surface pressure acting on the contact area between the inner circumferential surface of the front portion of the outer column11and the outer circumferential surface of the rear portion of the inner column10is reduced. In this state, the position of the steering wheel4in the vertical direction and the front-rear direction can be adjusted within a range in which the adjustment rod24can be displaced inside the long holes21,23.

After the steering wheel4is moved to a desired position, the adjustment lever25is rotated toward a direction (upward) opposite to the predetermined direction, whereby the dimension of the cam device26in the axial direction is increased. As a result, the interval between the inner surfaces facing each other in the driven-side cam28and the nut29(which correspond to a pair of pressing members) is contracted, whereby the sandwiched portions20,20are strongly pressed by the supporting plate members22,22. At the same time, the inner diameter of the portion of the front portion of the outer column11internally fitted with the rear portion of the inner column10is elastically contracted, whereby the surface pressure acting on the contact area between the inner circumferential surface of the front portion of the outer column11and the outer circumferential surface of the rear portion of the inner column10is increased. In this state, the position of the steering wheel4in the vertical direction and the front-rear direction is held at the adjusted position.

Incidentally, in order to ensure the flexibility of the portion of the front portion of the outer column11fitting on and holding the inner column10, the front end portion of the slit19is opened to a front edge of the outer column11. In this case, the rigidity of the front edge of the outer column11which is the open end side of the slit19becomes lowest, and the rigidity of the outer column11increases as proceeding toward the bottom end side of the slit19. Therefore, in accordance with the position of the steering wheel4in the front-rear direction, a force necessary for operating the adjustment lever25to contract the inner diameter of the front portion of the outer column11changes.

In this regard, Patent Document 1 discloses a structure in which a slit includes a main slit portion which is formed in an axial direction and a sub slit portion which is formed in a circumferential direction in at least the front end portion of both end portions of the main slit portion such that an end portion of the main slit portion in the axial direction is open to a center portion of the sub slit portion in the circumferential direction, and the shape of the slit as seen from the radial direction is a T shape or an H shape. With this structure, while it is possible to ensure the flexibility of the fitting and holding portion of the outer column, thereby reducing a force necessary for expanding or contracting the inner diameter of the fitting and holding portion, it is possible to alleviate concentration of stress on the end portions of the slit. However, even in this structure, there is room for improvement in order to stabilize a force necessary for operating the adjustment lever regardless of the position of the steering wheel in the front-rear direction.

BACKGROUND ART DOCUMENT

Patent Document

SUMMARY OF THE INVENTION

Problems to be Solved

The present invention has been made in view of the above described circumstances, and an object of the present invention is to implement a structure capable of stabilizing a three necessary for operating an adjustment lever regardless of the position of a steering wheel in a front-rear direction.

Means for Solving the Problems

The present invention provides an outer column for a telescopic steering device, the outer column including:

a main column body which is formed in a substantially cylindrical overall shape and has a slit formed long in an axial direction at a front portion thereof; and

a pair of sandwiched portions which are fixedly provided on the main column body to protrude upward or downward at positions interposing the slit therebetween in a width direction,

wherein a pair of front-rear long holes are formed long in a front-rear direction on the sandwiched portions at positions matching with each other, and

wherein in a rear end side portion of an outer surface of at least one sandwiched portion of the sandwiched portions, a dented portion is formed to be dented inward in the width direction at a position on a main column body side in a vertical direction.

Especially, in the outer column for the telescopic steering device according to the present invention, in the rear end side portion of the outer surface of at least one sandwiched portion of the sandwiched portions, the dented portion (non-contact portion is formed to be dented inward in the width direction at the position on the main column body side in the vertical direction (a lower half portion in a case of providing the sandwiched portions to protrude upward, and an upper half portion in a case of providing the sandwiched portions to protrude downward).

In the above outer column for the telescopic steering device according to the present invention, it is preferred that the dented portion be continuous to the front-rear long hole.

Further, it is preferred that a stepped portion formed between the dented portion and the sandwiched portion be formed to an opposite side to the main column body side with respect to a center position of the front-rear long hole in the vertical direction.

Further, it is preferred that a vertical dimension of the dented portion increase as proceeding toward a rear side.

Further, it is preferred that a vertical dimension of the sandwiched portions is larger at a rear end side portion of the main column body than at a front end side portion of the main column body.

The present invention further provides a telescopic steering device including a steering column, a supporting bracket, a rod member and an adjustment mechanism.

The steering column includes an inner column and an outer column externally fitted on a rear portion of the inner column and having a slit formed on a front portion thereof. Which is a fitting portion with the inner column such that an inner diameter of the front portion can be expanded or contracted based on the slit. A steering shaft is rotatably supported on the inner diameter side of this steering column. The steering shaft is configured by assembling an outer shaft and an inner shaft such that a total length of the steering shaft can be increased or decreased and which has a rear end portion where a steering wheel is supported and fixed.

The supporting bracket includes a pair of supporting plate members which sandwich a pair of sandwiched portions of the outer column from both sides in a width direction, and a mounting plate member which supports the supporting plate members to a vehicle body. The supporting plate members are formed with bracket-side through holes at a position which matches with front-rear long holes formed long in a front-rear direction on the sandwiched portions.

The rod member is inserted through the front-rear long holes and the bracket-side through holes.

The adjustment mechanism is configured to expand or contract an interval between a pair of pressing members provided at both end portions of the rod member based on an operation on an adjustment lever provided at an end portion of the rod member. When the interval is contracted, an interval between inner surfaces of the supporting plate members is contracted, whereby the inner surfaces of the supporting plate members and outer surfaces of the sandwiched portions are frictionally engaged such that a position of the outer column in the front-rear direction with respect to the inner column is fixed.

Especially, in the telescopic steering device according to the present invention, the outer column is the outer column according to the present invention as described above.

Advantages of the Invention

According to the outer column for the telescopic steering device and the telescopic steering device configured according to the present invention as described above, it is possible to stabilize a force necessary for operating the adjustment lever regardless of the position of the steering wheel in the front-rear direction. That is, in the rear end side portion of the outer surface of at least one sandwiched portion of the pair of sandwiched portions, the dented portion is formed to be dented inward in the width direction at a position on the main column body side in the vertical direction. Therefore, in a case where the position of the steering wheel in the front-rear direction is located on the front side from the center position of an adjustable range, forces of the pair of supporting plate members pressing the sandwiched portions from both sides in the width direction can be effectively used as a force for contracting the inner diameter of the fitting/holding portion of the inner column, which is the front portion of the outer column (the main column body). Therefore, a force necessary for operating the adjustment lever can be suppressed from increasing.

DETAILED DESCRIPTION OF EMBODIMENTS

First Embodiment

FIGS. 1 to 5show a first embodiment of the present invention. The present invention as well as the present embodiment is characterized by a structure capable of stabilizing a force necessary for operating an adjustment lever25(seeFIG. 10) (an operation force on the adjustment lever25) (capable of reducing change of the operation force on the adjustment lever25), regardless of a position of a steering wheel4(seeFIG. 9) in a front-rear direction.

The structure and operation of the other part are similar to those in the above described existing structure, and thus repeated drawings and descriptions will be omitted or simplified. Hereinafter, characteristic parts of the present invention will be mainly described.

In the present embodiment, an outer column includes a main outer column body38formed in a substantially cylindrical overall shape, and a pair of sandwiched portions20a,20aconfiguring a column-side bracket18a. The main outer column body38is formed with a slit19ain an upper surface of a front portion thereof (the left side ofFIGS. 1 to 4) to have a substantial T shape as seen from a radial direction. The slit19ais formed in order to reduce rigidity in the radial direction of the front portion of the main outer column body38for sufficiently increasing a contact pressure between an inner circumferential surface of the front portion of the main outer column body38and an outer circumferential surface of a rear portion of an inner column10aaccording to an operation on the adjustment lever25. The slit19aincludes a main slit portion33long in an axial direction, a sub slit portion34and a width-enlarged portion35. The main slit portion33is formed between the sandwiched portions20a,20ato extend in the axial direction (parallel to a center axis) of the outer column11a. The sub slit portion34is formed to extend in a circumferential direction in the front end portion of the main slit portion33such that a front end portion of the main slit portion33is connected to a center portion of the sub slit portion in the circumferential direction (such that the front end portion of the main slit portion33is opened to the center portion of the sub slit portion in the circumferential direction). The width-enlarged portion35is formed in a rear end portion of the main slit portion33in a substantially circular shape as seen from the radial direction such that the rear end portion of the main slit portion33is connected to a center portion of the width-enlarged portion in the circumferential direction (such that the rear end portion of the main slit portion33is opened to the center portion of the width-enlarged portion in the circumferential direction). However, as shown inFIG. 6, without forming the sub slit portion34, a front end portion of a slit19amay be opened to a front edge of the outer column11a.

The sandwiched portions20a,20aare integrally formed with the main outer column body38on an outer circumferential surface of the main outer column body38at positions interposing the main slit portion33of the slit19atherebetween in the width direction (the circumferential direction) and extend in parallel with each other. However, the sandwiched portions20a,20amay be formed by fixing separate members by welding or the like. In either case, the sandwiched portions20a,20aare formed with front-rear long holes21a,21along in the axial direction of the outer column11aat positions which match each other.

Further, in the present embodiment, in rear end side portions of the outer surfaces of the sandwiched portions20a,20a(in a case where the steering wheel4is located at a center position of the adjustable range, portions on the rear side from portions where an adjustment rod24is located), dented portions36,36are formed as non-contact portions to be dented inward in the width direction at lower half portions which are base half portions of the sandwiched portions20a,20a(half portions on the main outer column body38side in the vertical direction). That is, the width dimension of a rear end side portion of the column-side bracket18aconfigured by the sandwiched portions20a,20a(the interval between the outer surfaces of the rear end side portions of the sandwiched portions20a,20a) is smaller at the lower half portions than at the upper half portions.

Between the sandwiched surfaces (outer surfaces) of the sandwiched portions20a,20aand the dented portions36,36, there is formed a stepped portions39ain a rear side of the front-rear long hole21a, and there is formed a stepped portion39bin a column-center side of the front-rear long hole21a. The stepped portions39a,39bare connected to the front-rear long holes21a,21a. That is, at least a portion of the front-rear long holes21a,21ais continuous to the dented portions36,36.

Further, the stepped portion39awhich is formed between the dented portions36,36and the sandwiched surfaces of the sandwiched portions20a,20aare formed to an opposite side to the main outer column body side with respect to a vertically center position C of the front-rear long holes21a,21a.

The rear portion of the inner column10ais internally fitted in the front portion of the outer column11aas described above to be able to be displaced in the axial direction, accordingly, a telescopic steering column2ais configured. Further, the middle portion of the steering column2ais supported on a vehicle body1through a supporting bracket17a(seeFIG. 9). The supporting bracket17ais formed by bending a metal plate, such as a steel plate, capable of ensuring necessary strength and rigidity in a substantially U shape, and includes a mounting plate member37for supporting on the vehicle body, and a pair of supporting plate members22a,22ahanged down from the lower surface of the mounting plate member37and parallel to each other in the width direction. In a state where the sandwiched portions20a,20aare sandwiched from both sides in the width direction by the pair of the supporting plate members22a,22a, the adjustment rod24is inserted through the vertical long holes23,23in the supporting plate members22a,22aand front-rear long holes21a,21a. Further, an expansion/contraction mechanism (for example, the cam device26and the nut29shown inFIG. 10) incorporated in the adjustment rod24makes it possible to expand or contract the interval between the supporting plate members22a,22a, thereby adjusting the position of the outer column11in the vertical direction and the front-rear direction and holding the outer column11at the adjusted position.

According to the telescopic steering column device of the present embodiment as described above, regardless of the position of the steering wheel4in the front-rear direction, it is possible to reduce change of a force necessary for operating the adjustment lever25(seeFIG. 9). The reason will be described below.

As shown inFIG. 4A, in a state where the steering wheel4is moved to the front end position of the adjustable range (a state where the adjustment rod24is engaged with the rear end portions of the front-rear long holes21a,21a), the pair of supporting plate members22a,22aconfiguring the supporting bracket17aare located on both sides in the width direction of the rear end portion of the slit19ahaving relatively high rigidity in the outer column11a. In this state, if the adjustment lever25is operated to reduce the interval between the supporting plate members22a,22ain order to hold the position of the steering wheel4in the front-rear direction at the adjusted position (the front end position), the inner surfaces of the supporting plate members22a,22acome into contact with rear end side portions of the outer surfaces of the pair of the sandwiched portions20a,20a. In the present embodiment, since the dented portions36,36are formed in the lower half portions of the rear end side portions of the outer surfaces of the sandwiched portions20a,20ato be dented inward in the width direction, only the upper half portions of the outer surfaces of the sandwiched portions20a,20acome into contact with the inner surfaces of the supporting plate members22a,22a. According to an operation on the adjustment lever25, the supporting plate members22a,22aare elastically deformed so as to approach each other in the width direction as proceeding toward the lower end portions.

Therefore, in the present embodiment, in a case of elastically deforming the vicinity of the rear end portion of the slit19ahaving relatively high rigidity in the main slit portion33in order to reduce its diameter, it is possible to lengthen a distance L1from a portion which is a fulcrum of the elastic deformationFIG. 5A, a portion O of the main outer column body38which is an intersection between the main outer column body38and a virtual line perpendicular to the center axis of the outer column11aand extending in a horizontal direction) to a force point F1(seeFIG. 5A) which is the lower end portion of the contact portion between the outer surface of the sandwiched portions20a,20aand the inner surfaces of the supporting plate members22a,22a. Therefore, it is possible to efficiently use the supporting plate members22a,22apressing the sandwiched portions20a,20aas a force for contracting the inner diameter of the front portion of the main outer column body38. As a result, even in a case of elastically deforming the vicinity of the rear end portion of the slit19ahaving relatively high rigidity in the main outer column body38, it is possible to suppress a force necessary for operating the adjustment lever25from needlessly increasing.

On the other hand, as shown inFIG. 4C, in a state where the steering wheel4is moved to the rear end position of the adjustable range (a state where the adjustment rod24is engaged with the front end portions of the front-rear long holes21a,21a), a distance L2from a portion which is a fulcrum of the elastic deformation O (seeFIG. 5B) to a force point F2(seeFIG. 5B) which is the lower end portion of the contact portion between the outer surface of the sandwiched portions20a,20aand the inner surface of the supporting plate members22a,22abecomes shorter (becomes the same as that in the case of the existing structure). Also, as shown inFIG. 4B, in a state where the steering wheel4is moved to the center position of the adjustable range (a state where the adjustment rod24is engaged with the middle portion of the front-rear long holes21a,21a), a distance between a portion which is a fulcrum of elastic deformation and a force point which is the rear side portion of the lower end portion of the contact portion between the outer surface of the sandwiched portions20a,20aand the inner surface of both supporting plate members22a,22abecomes longer, and a distance between the portion which is a fulcrum of elastic deformation and the front side portion of the lower end portion of the contact portion becomes similarly shorter. That is, in a case of elastically deforming the vicinity of the front end portion to the middle portion of the slit19ahaving relatively low rigidity in the main outer column body38, a distance between a fulcrum of the elastic deformation and a force point is the same as that in the case of the existing structure. Therefore, regardless of the position of the steering wheel4in the front-rear direction, it is possible to stabilize a force necessary for operating the adjustment lever25.

In the present embodiment, since the front-rear long holes21a,21aare continuous to the dented portions36,36, the supporting plate members22a,22aare easily bent toward the dented portions36,36according to a claiming operation on the adjustment lever25, and a force necessary for operating the adjustment lever25is easily decreased.

Especially, since the stepped portion39awhich is formed between the dented portions36,36and the sandwiched surfaces of the sandwiched portions20a,20aare formed to the opposite side to the main outer column body side with respect to the vertically center position C of the front-rear long holes21a,21a, it is possible to further reduce a force necessary for operating the adjustment lever25.

Second Embodiment

FIG. 7shows a second embodiment of the present invention. In an outer column11baccording to the present invention, at a lower half portion of the rear end side portion of the outer surface of a pair of sandwiched portions20b,20b, a dented portions36ais formed such that its dimension in the vertical direction increases as proceeding toward the rear side. That is, stepped portions39which are formed between the dented portions36,36and the sandwiched surfaces of the sandwiched portions20a,20aare formed to be inclined such that the vertical dimension of the sandwiched portions20b,20bincreases as proceeding from the front end side portion toward the rear end side portion.

In the case of the present embodiment as described above, since it is possible to increase the distance from the position of a force point F of a force acting from the inner surfaces of the pair of supporting plate members22a,22a(seeFIGS. 4 to 5) to the fulcrum O as the steering wheel4is displaced toward the rear side, it is possible to make even a force necessary for operating the adjustment lever25(seeFIG. 9).

The configuration and operation of the other parts are the same as those of the above-described first embodiment, and thus repeated drawings and descriptions are omitted.

Third Embodiment

FIG. 8shows a third embodiment of the present invention. As shown inFIG. 8, a pair of sandwiched portions20ais thickened upward as proceeding toward the rear side of the vehicle body which is the right side ofFIG. 8, and the vertical dimension of the sandwiched portion20ais larger at a rear end side portion of the main outer column body38than at a front end side portion thereof.

The configuration and operation of the other parts are the same as those of the above described first embodiment, and thus repeated drawings and descriptions are omitted.

In the outer column11ashown inFIG. 1, since the side where the slit19aand the pair of sandwiched portions20a,20aare formed is the front side of the outer column11a, the other side can be referred to as the rear side. This is also applicable toFIGS. 7 and 8.

INDUSTRIAL APPLICABILITY

In the present invention, it is essential to implement a telescopic steering device for adjusting a position of a steering wheel in the front-rear direction. However, it is optional to implement a tilt steering device for adjusting the position of a steering wheel together with the telescopic steering device.

Further, the relation between the upper side and lower side of the steering column in the vertical direction may be reverse to that of the above-described embodiments. That is, the slit and the pair of sandwiched portions may be provided on the lower side of the outer column.

However, in order to ensure a space around knees of a driver, it is preferable that sandwiched portions be provided on the upper side from a center axis in the axial direction (the center axis in the front-rear direction) of the main column body.

Also the dented portion may be formed only in the outer surface of either one sandwiched portion of the pair of sandwiched portions.

This application is based on Japanese Patent Application No. 2014-040344, filed Mar. 3, 2014, and Japanese Patent Application No. 2014-143054, filed Jul. 11, 2014, the entire contents of which are incorporated herein by reference.

DESCRIPTION OF REFERENCE NUMERALS