JP2013185686A - Spline telescopic shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive spline telescopic shaft capable of suppressing the occurrence of abnormal noise for a long period of time.SOLUTION: An intermediate shaft 5 (spline telescopic shaft) includes a cylindrical outer shaft 40 having inner splines 41 and an inner shaft 50. The inner shaft 50 includes a first divided body 51 and a second divided body 52 which are divided in an axial direction X1. Outer splines 53, 54 of the respective divided bodies 51, 52 are fitted in the inner splines 41. A torsion coil spring 60 (elastic member) stored in the outer shaft 40 connects both the divided bodies 51, 52 in a rotating direction Z1. The torsion coil spring 60 applies a pressing force in a direction of shifting phases of the respective divided bodies 51, 52 to both the divided bodies 51, 52, and constantly maintains a clearance between both the splines 41, and 51, 52 at zero.

Description

  The present invention relates to a spline telescopic shaft.

In spline telescopic shafts used in automobiles and industrial machines, it is necessary to provide a circumferential (rotational direction) gap between the inner and outer splines in order to slide the inner shaft and outer shaft in the axial direction. However, due to the gap, there is a problem that abnormal noise is generated due to rattling noise.
Patent Document 1 proposes a technique for applying a resin coating to inner and outer splines.

JP 2011-38561 A

However, it is necessary to strictly manage the gap between the inner and outer splines, which increases the manufacturing cost.
In addition, if the resin coating is worn over a long period of time, the circumferential gap between the inner and outer splines increases, and there is a risk that abnormal noise (gap noise) may occur.
Accordingly, an object of the present invention is to provide an inexpensive spline telescopic shaft that can suppress the generation of abnormal noise over a long period of time.

  In order to achieve the object, the invention of claim 1 has a cylindrical outer shaft (40) having an inner spline (41) and outer splines (53, 54; 153, 154) meshing with the inner spline. The inner shaft (50; 150) including a plurality of divided bodies (51, 52; 151, 152) divided in the axial direction (X1) and the plurality of divided bodies accommodated in the outer shaft in the rotational direction. A spline telescopic shaft (5) provided with an elastic member (60) connected to (Z1) and generating an urging force in a direction to shift the phase of the plurality of divided bodies.

In addition, although the alphanumeric character in a parenthesis represents the corresponding component etc. in embodiment mentioned later, this does not mean that this invention should be limited to those embodiment as a matter of course. The same applies hereinafter.
According to a second aspect of the present invention, the elastic member may include a torsion coil spring (60) that is twisted in the rotational direction.

According to a third aspect of the present invention, the initial torque of the elastic member may be larger than the maximum transmission torque of the spline telescopic shaft.
Further, as in claim 4, the convex portion (155) provided on the end surface (151b) of the adjacent divided body is fitted into the concave portion (156) provided on the end surface (152b) of the adjacent divided body. May be.

  According to the invention of claim 1, the urging force of the elastic member works so as to shift the phases of the plurality of divided bodies constituting the inner shaft from each other. Therefore, even when both splines wear due to long-term use, the amount of phase shift of the plurality of divided bodies can be increased according to the amount of wear, and the gap between both splines can be maintained at zero. . As a result, it is possible to suppress the occurrence of abnormal noise (tooth noise) over a long period of time. In addition, it is not necessary to strictly manage the gap between the two splines, and the manufacturing cost can be reduced.

According to the second aspect of the present invention, it is possible to generate a torsional torque that is stable over a long period of time by using a torsion coil spring as the elastic member.
According to invention of Claim 3, the some division body of an inner shaft can always be made to contribute to torque transmission. The occurrence of uneven wear can be suppressed and durability can be improved.
According to the fourth aspect of the present invention, since the adjacent divided bodies are unevenly coupled in the axial direction, the bending rigidity of the entire spline telescopic shaft can be increased.

1 is a schematic configuration diagram of a vehicle steering apparatus to which a spline telescopic shaft according to an embodiment of the present invention is applied. It is a partially broken side view of the intermediate shaft as a spline telescopic shaft. It is an expanded sectional view of the important section of the inner axis of an intermediate axis. It is a schematic diagram which shows the phase shift of the 2nd division body on the basis of the 1st division body of an inner shaft. FIG. 5 is an enlarged cross-sectional view of the intermediate shaft along the line VV in FIG. 2. FIG. 6 is an enlarged cross-sectional view of the intermediate shaft along the line VI-VI in FIG. 2. It is an expanded sectional view of the principal part of the inner shaft used for the spline telescopic shaft (intermediate shaft) of another embodiment of the present invention.

Preferred embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic configuration diagram of a vehicle steering apparatus having an intermediate shaft to which a spline telescopic shaft according to an embodiment of the present invention is applied. Referring to FIG. 1, a vehicle steering apparatus 1 includes a steering shaft 3 coupled to a steering member 2 such as a steering wheel, and an intermediate shaft as a spline telescopic shaft coupled to the steering shaft 3 via a universal joint 4. 5, a pinion shaft 7 connected to the intermediate shaft 5 via a universal joint 6, and a rack shaft 8 as a steered shaft having a rack 8 a meshing with a pinion 7 a provided in the vicinity of the end of the pinion shaft 7. I have.

  A steering mechanism A1 is configured by a rack and pinion mechanism including the pinion shaft 7 and the rack shaft 8. The rack shaft 8 is supported by a housing 10 fixed to the vehicle body side member 9 so as to be movable in an axial direction along the left-right direction of the vehicle (a direction orthogonal to the paper surface). Although not shown, each end of the rack shaft 8 is connected to a corresponding steered wheel via a corresponding tie rod and a corresponding knuckle arm.

  The steering shaft 3 includes a first steering shaft 11 and a second steering shaft 12 that are connected coaxially. The first steering shaft 11 has an upper shaft 13 and a lower shaft 14 which are fitted so as to be able to rotate together and be slidable relative to each other in the axial direction using spline coupling. One of the upper shaft 13 and the lower shaft 14 constitutes an inner shaft, and the other constitutes a cylindrical outer shaft.

The second steering shaft 12 includes an input shaft 15 connected to the lower shaft 14 so as to be able to rotate together, an output shaft 16 connected to the intermediate shaft 5 through the universal joint 4, and the input shaft 15 and the output shaft 16 And a torsion bar 17 for connecting the two in a relatively rotatable manner.
The steering shaft 3 is rotatably supported by a steering column 20 fixed to the vehicle body side members 18 and 19 via a bearing (not shown).

The steering column 20 includes a cylindrical upper jacket 21 and a cylindrical lower jacket 22 that are fitted so as to be relatively movable in the axial direction, and a housing 23 connected to the lower end in the axial direction of the lower jacket 22. The housing 23 houses a speed reduction mechanism 25 that decelerates the power of the steering assisting electric motor 24 and transmits it to the output shaft 16.
The speed reduction mechanism 25 has a drive gear 26 that is connected to a rotation shaft (not shown) of the electric motor 24 so as to be able to rotate together with the drive gear 26 and a driven gear 27 that meshes with the drive gear 26 and rotates together with the output shaft 16. . The drive gear 26 is composed of, for example, a worm shaft, and the driven gear 27 is composed of, for example, a worm wheel.

  The steering column 20 is fixed to the vehicle body side members 18 and 19 via an upper bracket 28 on the vehicle rear side and a lower bracket 29 on the vehicle front side. The upper bracket 28 can be fixed to the upper jacket 21 of the steering column 20 via a column bracket (not shown). The upper bracket 28 uses a fixing bolt (stud bolt) 30 that protrudes downward from the vehicle body side member 18, a nut 31 that is screwed to the fixing bolt 30, and a capsule 32 that is detachably held by the upper bracket 28. The vehicle body side member 18 is fixed.

The lower bracket 29 is fixed to the housing 23 of the steering column 20. Further, the lower bracket 29 is fixed to the vehicle body side member 19 using a fixing bolt (stud bolt) 33 protruding from the vehicle body side member 19 and a nut 34 screwed into the fixing bolt 33.
1 and 2, the intermediate shaft 5 as a spline telescopic shaft is spline-fitted so that it can slide along the axial direction X1 and transmit torque along the cylindrical outer shaft 40 and the inner shaft 50. Is formed. One of the outer shaft 40 and the inner shaft 50 constitutes the upper shaft, and the other constitutes the lower shaft.

In this embodiment, the outer shaft 40 is connected to the universal joint 4 as an upper shaft, and the inner shaft 50 is connected to the universal joint 6 as a lower shaft. A lubricant such as grease may be interposed between the outer shaft 40 and the inner shaft 50. Thereby, sliding resistance when the outer shaft 40 and the inner shaft 50 move relative to each other in the axial direction X1 can be reduced.
In this embodiment, the spline telescopic shaft is described as applied to the intermediate shaft 5, but the spline telescopic shaft of the present invention is applied to the first steering shaft 11, and the first steering shaft 11 has a telescopic adjustment function, You may make it fulfill | perform an impact absorption function. In this embodiment, the vehicle steering apparatus 1 is described as an electric power steering apparatus. However, the spline telescopic shaft of the present invention may be applied to a vehicle steering apparatus for manual steering. .

  As shown in FIG. 2 and FIG. 3 which is an enlarged sectional view, the outer shaft 40 has an inner spline 41 on its inner periphery 40a. The inner shaft 50 includes a first divided body 51 and a second divided body 52 that are divided in the axial direction X1. Outer splines 53 and 54 that mesh with the inner spline 41 are formed on the outer peripheries 51a and 52a (corresponding to the outer perimeter of the inner shaft 50) of the respective divided bodies 51 and 52, respectively. That is, the divided bodies 51 and 52 of the inner shaft 50 are both spline-fitted to the outer shaft 40.

Within the outer shaft 40, the end surface 51b of the first divided body 51 and the end surface 52b of the second divided body 52 face each other in the axial direction X1. A metal torsion coil spring 60 as an elastic member is accommodated in the outer shaft 40. The torsion coil spring 60 is interposed between the both end faces 51b and 52b in a state where it is twisted in the rotational direction Z1, that is, in a state where the initial torque T1 is loaded.
The first divided body 51 and the second divided body 52 of the inner shaft 50 are connected in the rotation direction Z1 via a torsion coil spring 60 as an elastic member. Specifically, one end 61 of the torsion coil spring 60 is engaged with an engagement hole 51 c provided in the end surface 51 b of the first divided body 51. The other end 62 of the torsion coil spring 60 is engaged with an engagement hole 52 c provided in the end surface 52 b of the second divided body 52. As a result, torque can be transmitted between the split bodies 51 and 52 via the torsion coil spring 60.

The torsion coil spring 60 applies a biasing force that shifts the phases of the first divided body 51 and the second divided body 52 to the first divided body 51 and the second divided body 52.
Referring to FIG. 4 which is a schematic diagram, the phase shift of the second divided body 52 with respect to the first divided body 51 in the inner shaft 50 in a free state before being incorporated in the outer shaft 40 is defined as an angle θ1. When the inner shaft 50 is incorporated into the outer shaft 40, the phase shift of the second divided body 52 with respect to the first divided body 51 becomes an angle θ2 (θ2 is zero or a value close to zero). That is, the torsion coil spring 60 in the assembled state is twisted from the free state at an angle (θ1−θ2) corresponding to the difference between the angle θ1 and the angle θ2.

The torsion coil spring 60 imparts a repulsive force (repulsive force for returning the phase shift to the angle θ1) corresponding to the angle (θ1−θ2) to both the split bodies 51 and 52. That is, the torsion coil spring 60 urges the first divided body 51 and the second divided body 52 to rotate in the opposite directions with the initial torque T1 (see FIGS. 5 and 6).
Accordingly, as shown in FIGS. 5 and 6, the first outer spline 53 having a pair of tooth surfaces 53a and 53b and the second outer spline 54 having a pair of tooth surfaces 54a and 54b are mutually connected with respect to the rotation direction. The tooth surfaces 53a and 54b on the opposite side are in contact with the corresponding tooth surfaces of the inner spline 41.

In addition, the initial torque T1 (see FIGS. 5 and 6) of the torsion coil spring 60 in a state where the two divided bodies 51 and 52 are connected in the outer shaft 40 is the maximum transmission torque TMAX (see FIG. 5 and FIG. 6) of the intermediate shaft 5 as the spline telescopic shaft. (T1> TMAX).
According to the present embodiment, the urging force of the elastic member (torsion coil spring 60) acts in a direction that shifts the phases of the two split bodies 51 and 52 that constitute the inner shaft 50 from each other. Therefore, when both the splines 41; 51, 52 are worn due to long-term use, the amount of phase shift between the two divided bodies 51, 52 is increased according to the amount of wear. Thereby, since the clearance gap between both the splines 41; 51 and 52 can be maintained to zero over a long period of time, generation | occurrence | production of abnormal noise (tooth rattling sound) can be suppressed over a long period of time. Moreover, it is not necessary to strictly manage the gap between the splines 41; 51, 52, and the manufacturing cost can be reduced.

In addition, the torsion coil spring 60 can be used as the elastic member to generate a stable torsion torque for a long period of time.
Further, since the initial torque T1 of the torsion coil spring 60 is larger than the maximum transmission torque TMAX of the intermediate shaft 5 serving as the spline expansion / contraction shaft, the plurality of divided bodies 51 and 52 of the inner shaft 50 are always used for torque transmission. Can contribute. Thereby, generation | occurrence | production of uneven wear can be suppressed and durability can be improved.

Next, FIG. 7 shows an inner shaft 150 used for a spline telescopic shaft according to another embodiment of the present invention. This embodiment is different from the embodiment of FIG. 3 in that the axial convex portion 155 provided on the end surface 151b of the first divided body 151 of the inner shaft 150 is the end surface 152b of the second divided body 152 of the inner shaft 150. Is fitted in an axial recess 156 provided on the surface.
A first outer spline 153 is formed on the outer periphery 15 a of the first divided body 151, and a second outer spline 154 is formed on the outer periphery 152 a of the second divided body 152. One end 61 of the compression coil spring 60 is locked in the engagement hole 151c provided in the convex portion 155, and the other end 62 of the compression coil spring 60 is locked in the engagement hole 152c provided in the concave portion 156. Yes.

Although not shown, the cross-sectional shape of the convex portion 155 and the cross-sectional shape of the concave portion 156 may be circular. Moreover, the cross-sectional shape of the recessed part 156 may be a rectangle, and the cross-sectional shape of the convex part 155 may be an oval shape. In the constituent elements of this embodiment, the same constituent elements as those of the embodiment of FIG. 3 are denoted by the same reference numerals as those of the constituent elements of the embodiment of FIG.
According to this embodiment, the same effect as the embodiment of FIG. 3 can be obtained. In addition, since the two split bodies 151 and 152 of the inner shaft 150 are unevenly coupled in the axial direction X1, the bending rigidity of the intermediate shaft 5 as a whole can be increased.

The present invention is not limited to the above-described embodiment. For example, the initial torque T1 of the elastic member (torsion coil spring 60) may be equal to or less than the maximum transmission torque TMAX of the spline telescopic shaft (intermediate shaft 5) ( T1 ≦ TMAX). Even in that case, it is possible to suppress the generation of abnormal noise (gap sound) over a long period of time.
Further, instead of the torsion coil spring, a rod-like elastic member (torsion bar) may be used as the elastic member. Moreover, you may provide three division bodies which comprise an inner axis | shaft. In addition, various modifications can be made within the scope of the claims of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle steering device, 3 ... Steering shaft, 5 ... Intermediate shaft (spline telescopic shaft), 40 ... Outer shaft, 40a ... Inner circumference, 41 ... Inner spline, 50 ... Inner shaft, 51 ... First divided body, 51a ... outer periphery, 51b ... end face, 51c ... engagement hole, 52 ... second divided body, 52a ... outer periphery, 52b ... end face, 52c ... engagement hole, 53 ... first outer spline, 54 ... second outer spline, 60 ... Torsion coil spring (elastic member), 61 ... one end, 62 ... other end, 150 ... inner shaft, 151 ... first divided body, 151a ... outer periphery, 151b ... end face, 152 ... second divided body, 152a ... outer periphery, 152b ... End face, 153... First outer spline, 154. Second outer spline, 155... Convex, 156 .. Concavity, .theta.1, .theta.2 (phase shift) angle, T1 ... Initial torque, X1.

Claims (4)

A cylindrical outer shaft having an inner spline;
Each having an outer spline meshing with the inner spline, an inner shaft including a plurality of divided bodies divided in the axial direction;
A spline telescopic shaft comprising: an elastic member that is housed in the outer shaft and connects the plurality of divided bodies in a rotation direction and generates a biasing force in a direction that shifts the phases of the plurality of divided bodies.   The spline telescopic shaft according to claim 1, wherein the elastic member includes a torsion coil spring that is twisted in the rotation direction.   3. The spline telescopic shaft according to claim 1, wherein an initial torque of the elastic member is larger than a maximum transmission torque of the spline telescopic shaft.   The spline telescopic shaft according to any one of claims 1 to 3, wherein a convex portion provided on an end surface of an adjacent divided body is fitted in a concave portion provided on an end surface of the adjacent divided body.

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