JP2023005441A - Steering device - Google Patents

Abstract

To provide a steering device capable of inhibiting from getting larger in size.SOLUTION: A steering device 100 includes: a turning mechanism 2 that rotates a turning wheel 1 of a vehicle about a turning axis; a power source 3 that applies a drive force for turning the turning wheel 1, to the turning mechanism; an input shaft 5 coupled to the power source 3; an output shaft 15 coupled to a support member (hub 6) supporting the turning wheel 1; a rectilinear motion guide part 14 that guides rectilinear motion of the output shaft 15 with respect to the input shaft 5; a universal joint 13 that is interposed between the input shaft 5 and the output shaft 15 and supports oscillatably the output shaft 15 via the rectilinear motion guide part 14; and a panel 17 interposed between the rectilinear motion guide part 14 and the output shaft 15 or the support member. The rectilinear motion guide part 14 being disposed near the universal joint 13, supports the output shaft 15 so that the output shaft can freely rectilinearly move and transmit torque.SELECTED DRAWING: Figure 1

Description

The present invention relates to a steering system.

2. Description of the Related Art Among steering devices, there is known a steering device in which a motor for driving a shaft serving as a rotation axis for steering is installed in a vehicle body (see, for example, Patent Document 1). Such a steering apparatus is provided with a universal joint that rockably supports the output shaft, and the universal joint allows precession of the output shaft with respect to the input shaft.

JP 2020-19459 A

Here, the output shaft includes a first support portion arranged on the swing center side and a second support portion arranged at a position away from the swing center. The spring is telescopically supported by the part. Further, the second support portion has a linear motion guide mechanism, and this linear motion guide mechanism allows expansion and contraction of the output shaft. Therefore, when the output shaft expands and contracts, the distance between the linear motion guide mechanism and the swing center changes. The linear motion guide mechanism supports a bending moment when a load is applied to the steered wheels, but the bending moment acting on the linear motion guide mechanism also fluctuates due to the variation in the distance described above. Due to this variation, the linear motion guide mechanism must be strong enough to withstand the largest bending moment, which is one of the factors leading to an increase in the size of the linear motion guide mechanism, that is, an increase in the size of the steering system.

SUMMARY OF THE INVENTION An object of the present invention is to provide a steering apparatus capable of suppressing an increase in size.

In order to solve the above problems, a steering system according to an aspect of the present invention includes a steering mechanism that rotates steerable wheels of a vehicle about a steerable shaft, and a steering mechanism that applies a driving force for turning the steerable wheels. a power source applied to the power source, an input shaft connected to the power source, an output shaft connected to a support member that supports the steered wheels, a linear motion guide portion that guides the linear motion of the output shaft with respect to the input shaft, and an input a universal joint disposed between the shaft and the output shaft to oscillatably support the output shaft via the linear motion guide; a spring interposed between the linear motion guide and the output shaft or the support member; It has The linear motion guide part supports the output shaft so as to be linearly movable and torque transmissible while being arranged in the vicinity of the universal joint.

ADVANTAGE OF THE INVENTION According to this invention, the steering apparatus which can suppress enlargement can be provided.

1 is a schematic diagram showing a configuration of a main part of a steering system according to an embodiment; FIG. 1 is a perspective view showing a schematic configuration of a universal joint according to an embodiment; FIG. 1 is an exploded perspective view of a universal joint according to an embodiment; FIG. FIG. 6 is an explanatory diagram showing a state in which the output shaft according to the embodiment has moved with respect to the linear motion guide; FIG. 5 is an explanatory diagram showing theoretical bending moments at respective parts when a lateral load is applied to the steered wheels according to the embodiment; FIG. 10 is a schematic diagram showing a main configuration of a steering device according to a modified example;

Hereinafter, embodiments will be specifically described with reference to the drawings. It should be noted that the embodiments described below are all comprehensive or specific examples. Numerical values, shapes, materials, constituent elements, arrangement positions of constituent elements, connection forms, and the like shown in the following embodiments are examples, and are not intended to limit the present invention. In addition, among the constituent elements in the following embodiments, constituent elements that are not described in independent claims representing the highest concept will be described as arbitrary constituent elements.

In addition, the drawings are schematic diagrams in which emphasis, omissions, and ratios are appropriately adjusted in order to illustrate the present invention, and may differ from actual shapes, positional relationships, and ratios.

A steering system 100 according to the present embodiment is, for example, a steering system used in a vehicle equipped with a strut-type suspension mechanism. FIG. 1 is a schematic diagram showing the main configuration of a steering system 100 according to an embodiment. With the axial direction of the output shaft 15 as a reference, the tire house 4 side is the upper side, and the ground side is the lower side.

As shown in FIG. 1 , the steering device 100 includes a steering mechanism 2 that rotates the steerable wheels 1 around the steering shaft, and a power source that provides the steering mechanism 2 with a driving force for steering the steerable wheels 1 . 3.

The power source 3 is, for example, a motor, and is arranged above the tire house 4 of the vehicle. An input shaft 5 of the steering mechanism 2 is connected to the rotating shaft of the power source 3 . The input shaft 5 is arranged in the tire housing 4 and has a shape with an open bottom end. The tire house 4 is a part of the vehicle body that forms a wheel house.

The steering mechanism 2 includes a knuckle 7 (supporting member) attached to the hub 6 of the steerable wheel 1, a lower arm 9 connected to the lower portion of the knuckle 7 via a ball joint 8, and an upper portion of the knuckle 7. a strut 10; One end of a drive shaft 12 is connected to the hub 6 via a constant velocity joint 11 . The strut 10 is arranged in the tire house 4 of the vehicle and supported by the tire house 4 .

Next, the strut 10 will be described in detail. The strut 10 has an input shaft 5 , a universal joint 13 , a linear guide portion 14 and an output shaft 15 .

The input shaft 5 is connected to the rotating shaft of the power source 3 as described above, and the universal joint 13 is connected to its lower end. Rotation from the power source 3 is thereby transmitted to the universal joint 13 via the input shaft 5 . An upper end portion of the output shaft 15 is accommodated inside the input shaft 5 .

The universal joint 13 is arranged between the input shaft 5 and the output shaft 15 and is a joint that transmits rotation from the input shaft 5 to the output shaft 15 via the linear motion guide portion 14 . The universal joint 13 is a joint for allowing precession motion of the linear guide portion 14 and the output shaft 15 with respect to the input shaft 5 .

FIG. 2 is a perspective view showing a schematic configuration of the universal joint 13 according to the embodiment. FIG. 3 is an exploded perspective view of the universal joint 13 according to the embodiment. As shown in FIGS. 2 and 3 , the universal joint 13 is flat as a whole and includes an inner frame 131 , an intermediate frame 132 and an outer frame 133 .

The inner frame 131 is an annular frame made of metal. Specifically, a pair of through holes 1311 penetrate the inner frame 131 along the radial direction, and these through holes 1311 are arranged so as to face each other in the radial direction of the inner frame 131 . there is Assuming that the axial direction of the pair of through-holes 1311 is a first direction Y1 and the direction orthogonal to the first direction Y1 is a second direction Y2, the pair of through-holes 1311 are positioned at the center of the inner frame 131 in the second direction Y2. are placed.

The intermediate frame 132 is an annular frame made of metal and arranged outside the inner frame 131 . The intermediate frame 132 is arranged concentrically with the inner frame 131 . A pair of through holes 1321 are arranged in the intermediate frame 132 along the first direction Y1. Each through-hole 1321 is arranged in the center of the intermediate frame 132 in the second direction Y2 and penetrates the intermediate frame 132 along the first direction Y1. The pair of through holes 1321 of the intermediate frame 132 respectively correspond to the pair of through holes 1311 of the inner frame 131 . For example, a shaft (not shown) is rotatably inserted through one through hole 1321 and one through hole 1311, and a shaft (not shown) is rotatably inserted through the other through hole 1321 and the other through hole 1311. It is As a result, the intermediate frame 132 and the inner frame 131 rotate relative to each other in the first direction Y1.

A pair of through holes 1322 are arranged in the intermediate frame 132 along the second direction Y2. Each through-hole 1322 is arranged in the center of the intermediate frame 132 in the first direction Y1 and passes through the intermediate frame 132 in the second direction Y2.

The outer frame 133 is an annular metal frame and is arranged outside the intermediate frame 132 . The outer frame 133 is arranged concentrically with the intermediate frame 132 . A pair of through holes 1331 are arranged in the outer frame body 133 along the second direction Y2. Each through-hole 1331 is arranged in the center of the outer frame 133 in the first direction Y1 and passes through the outer frame 133 in the second direction Y2. The pair of through holes 1331 of the outer frame 133 respectively correspond to the pair of through holes 1322 of the intermediate frame 132 . For example, the shaft 16 (see FIG. 1) is rotatably inserted through one through hole 1331 and one through hole 1322, and the shaft 16 is rotatable through the other through hole 1331 and the other through hole 1322. freely inserted. As a result, the outer frame 133 and the intermediate frame 132 rotate relative to each other in the second direction Y2. In addition, in the universal joint 13, each shaft may be rotatably attached to each through hole via a bearing.

A lower end portion of the input shaft 5 is fixed to the outer frame body 133 . Therefore, the rotational motion of the input shaft 5 is transmitted to the outer frame body 133 .

In a state in which the inner frame 131, the intermediate frame 132, and the outer frame 133 are not tilted, they are flat as a whole (see FIG. 1). Specifically, when the intermediate frame 132 is not tilted with respect to the outer frame 133 and the inner frame 131 is not tilted with respect to the intermediate frame 132 , the intermediate frame 132 is positioned within the outer frame 133 . and the inner frame body 131 are accommodated, and the universal joint 13 has a flat shape as a whole.

As shown in FIG. 1, the linear motion guide portion 14 is a portion that guides the linear movement of the output shaft 15 with respect to the input shaft 5, and supports the output shaft 15 for linear movement and torque transmission. Specifically, the direct-acting guide portion 14 is a tubular member having a flange portion 141 on its upper portion. The flange portion 141 is fixed to the upper surface of the inner frame member 131 in a state in which the portion of the linear motion guide portion 14 below the flange portion 141 is accommodated in the opening of the inner frame member 131 . As a result, the linear motion guide portion 14 operates together with the inner frame member 131 . Further, the linear motion guide portion 14 is formed in a flat shape as a whole, and the length in the axial direction is approximately the same as the length in the axial direction of the universal joint 13 .

A guide groove (not shown) is formed along the axial direction of the linear motion guide portion 14 on the inner peripheral surface of the linear motion guide portion 14 . A projection (not shown) provided on the outer peripheral surface of the output shaft 15, which will be described later, is engaged with the guide groove so as to be slidable in the axial direction. The ridges restrict rotation of the output shaft 15 in the circumferential direction when engaged with the guide grooves. Therefore, although the output shaft 15 slides in the axial direction with respect to the linear guide portion 14, it cannot rotate in the circumferential direction. In other words, the linear motion guide portion 14 guides the linear motion of the output shaft 15 with respect to the input shaft 5 and can transmit the torque transmitted from the input shaft 5 to the universal joint 13 to the output shaft 15. .

Here, as described above, one of the intermediate frame 132 and the inner frame 131 is rotatable with respect to the other around the first direction Y1 as the rotation axis. One of them is rotatable with respect to the other about the second direction Y2 as a rotation axis. For example, when the outer frame 133 fixed to the input shaft 5 is used as a reference, the intermediate frame 132 rotates about the second direction Y2 as a rotation axis, and the inner frame 131 rotates about the first direction Y1 as a rotation axis. do. That is, the linear motion guide portion 14 and the output shaft 15 connected to the inner frame 131 are rotated to the input shaft 5 by the rotation of the intermediate frame 132 with respect to the inner frame 131 and the rotation of the outer frame 133 with respect to the intermediate frame 132. It is supported so that it can swing freely. Therefore, the linear guide portion 14 and the output shaft 15 can precess with respect to the input shaft 5 . Thus, the precession motion (precession motion) of the linear guide portion 14 and the output shaft 15 with respect to the input shaft 5 is allowed by the universal joint 13 . Here, the precession is a conical motion like a pestle seen in the pivot of a spinning top, for example.

The output shaft 15 has a lower end connected to the knuckle 7 and is a portion that outputs torque to the steered wheels 1 via the knuckle 7 . Specifically, the output shaft 15 is a shaft that accommodates a shock absorber (not shown) inside. The shock absorber is connected to the knuckle 7 and absorbs shock generated between the output shaft 15 and the knuckle 7 .

A protruding portion (not shown) extending in the axial direction is formed on the outer peripheral surface of the upper portion of the output shaft 15 . The upper portion of the output shaft 15 is inserted into the linear motion guide portion 14 so that the protruding portion engages with the guide groove of the linear motion guide portion 14 . As described above, the output shaft 15 is slidable with respect to the linear motion guide portion 14 by cooperation of the ridge portion and the guide groove, and the torque from the linear motion guide portion 14 is transmitted. It's like

An intermediate portion of the output shaft 15 is provided with a flange portion 151 protruding outward from the outer peripheral surface over the entire circumference. A spring 17 made of a coil spring is provided between the collar portion 151 and the direct-acting guide portion 14 , and the spring 17 applies a constant biasing force to the collar portion 151 , that is, the output shaft 15 . . Therefore, even if the output shaft 15 moves from the reference position with respect to the direct-acting guide portion 14, the biasing force from the spring 17 causes the output shaft 15 to return to the reference position.

FIG. 4 is an explanatory diagram showing a state in which the output shaft 15 according to the embodiment has moved with respect to the linear guide portion 14. As shown in FIG. FIG. 4(a) shows a state in which the output shaft 15 is extended with respect to the linear motion guide 14, and FIG. showing. 4A, the upper portion of the output shaft 15 hardly protrudes from the linear guide portion 14, whereas in FIG. ing. In either case, the linear guide portion 14 overlaps the universal joint 13 when viewed from the front (when viewed in a direction orthogonal to the axial direction of the output shaft 15). In other words, the linear guide portion 14 always overlaps the center of the precession when viewed from the front.

FIG. 5 is an explanatory diagram showing the theoretical bending moment M at each part when a lateral load F is applied to the steered wheels 1 according to the embodiment. As shown in FIG. 5, when a lateral load F is applied to the steered wheels 1, the bending moment M becomes maximum at the position of the ball joint 8, but at the universal joint 13 the bending moment M becomes zero. As described above, the linear motion guide portion 14 overlaps the universal joint 13 in a front view, so the bending moment acting on the linear motion guide portion 14 is also theoretically zero.

As described above, in the steering apparatus 100 according to the present embodiment, since at least part of the linear motion guide portion 14 is accommodated in the universal joint 13, the center P of the precession caused by the universal joint 13 and the direct acting guide portion 14 can be overlapped when viewed from the front. In other words, the bending moment acting on the linear guide portion 14 can be minimized. As a result, the linear motion guide portion 14 can be designed while suppressing the influence of the bending moment. If an increase in the size of the linear guide portion 14 can be suppressed, an increase in the size of the steering device 100 itself can also be suppressed.

In addition, since the inner frame 131, the intermediate frame 132, and the outer frame 133 can be arranged on the same plane, the universal joint 13 can be made thin. Therefore, it is possible to make the steering device 100 more compact. In addition, since the universal joint 13 is made thinner, the overlapping length of the universal joint 13 with respect to the output shaft 15 can be suppressed, and the stroke length of the output shaft 15 can be secured.

Further, since the steering device 100 allows the precession of the output shaft 15 and the linear motion guide portion 14, it can be suitably employed in a vehicle equipped with a strut-type suspension mechanism. In particular, it is preferable that the strut-type suspension mechanism be supported so as to be able to swing according to tilting of the steerable wheels connected to the lower end side of the mechanism. Various joints may be used for the support structure of the strut-type suspension mechanism, but they must be accommodated in a limited space, which may make installation difficult. However, if the steering device 100, whose size is suppressed as described above, is adopted as the support structure of the strut-type suspension mechanism, the support structure can be easily accommodated in a limited space.

Further, since the linear motion guide portion 14 is flat as a whole, the length of overlap of the linear motion guide portion 14 with respect to the output shaft 15 can be suppressed, and the stroke length of the output shaft 15 can be secured. be.

Although the steering system according to the present invention has been described above based on the above embodiment, the present invention is not limited to the above embodiment.

For example, in the embodiment described above, the case where at least part of the linear motion guide portion 14 is housed inside the universal joint 13 has been exemplified. However, the direct-acting guide portion 14a may be arranged in the vicinity of the universal joint 13 as in a modification described later.

FIG. 6 is a schematic diagram showing the main configuration of a steering device 100A according to a modification. In the following description, parts that are the same as those in the above-described embodiment are denoted by the same reference numerals, and description thereof may be omitted. As shown in FIG. 6, the flange portion 141 of the linear motion guide portion 14a is fixed to the lower surface of the inner frame body 131. As shown in FIG. As a result, the linear guide portion 14a protrudes from the universal joint 13 as a whole. In this case as well, the center P of the precession caused by the universal joint 13 and the linear guide portion 14a can be arranged close to each other. That is, the bending moment acting on the linear motion guide portion 14 can be reduced. As a result, the linear motion guide portion 14a can be designed while suppressing the influence of the bending moment, so that the size increase of the linear motion guide portion 14a can be suppressed. If an increase in size of the linear guide portion 14a can be suppressed, an increase in size of the steering device 100A itself can also be suppressed. Here, the vicinity of the universal joint 13 is a range in which the distance L1 from the axial center P1 of the linear motion guide portion 14a to the universal joint 13 is shorter than the axial length L2 of the universal joint 13. good. In the vicinity of the universal joint 13 , all or part of the linear guide portion may protrude from above the universal joint 13 .

Further, in the above-described embodiment, the case where the lower end portion of the spring 17 is provided on the flange portion 151 of the output shaft 15 is exemplified. However, the lower end of the spring may be provided on the knuckle (support member). In this case, the collar portion of the output shaft can be reduced.

Moreover, in the above-described embodiment, the steering apparatus used in a vehicle equipped with a strut-type suspension mechanism has been exemplified. However, it is also possible to apply the characteristic configuration of the present disclosure to a steering device used in a vehicle equipped with other types of suspension mechanisms. Other methods include a multi-link suspension mechanism and the like.

Also, the universal joint may be other than the universal joint 13 described above. Other universal joints include, for example, universal joints with spherical bearings, universal joints with couplings, and the like.

Further, in the above embodiment, the case where the shock absorber is housed inside the output shaft 15 is exemplified. However, a shock absorber may be arranged outside the output shaft. In this case, the output shaft may be solid or hollow.

Moreover, in the present embodiment, the steered wheels 1 driven by the drive shaft 12 are illustrated, but the steered wheels may be driven by an in-wheel motor or the like.

In addition, in the present embodiment, the spring 17 made of a coil spring is exemplified, but the spring 17 may be an air spring, a torsion bar spring, or another type of elastic body.

In addition, forms obtained by applying various modifications to the embodiments that a person skilled in the art can think of, or realized by arbitrarily combining the constituent elements and functions of the embodiments and modifications without departing from the scope of the present invention. Also included in the present invention.

INDUSTRIAL APPLICABILITY The present invention is applicable to a steering system in which precession of the output shaft with respect to the input shaft is allowed.

DESCRIPTION OF SYMBOLS 1... Steerable wheel 2... Steering mechanism 3... Power source 4... Tire house 5... Input shaft 6... Hub 7... Knuckle (supporting member) 8... Ball joint 9... Lower arm 10... Strut , 11... constant velocity joint, 12... drive shaft, 13... universal joint, 14, 14a... linear motion guide part, 15... output shaft, 16... shaft body, 17... spring, 100, 100A... steering device, 131... inside Frame 132 Intermediate frame 133 Outer frame 141, 151 Flange 1311, 1321, 1322, 1331 Through hole F Load L1 Distance L2 Length M Moment P, P1... center, Y1... first direction, Y2... second direction

Claims (4)

a steering mechanism that rotates the steered wheels of the vehicle about the steered shaft;
a power source that provides the steering mechanism with a driving force for steering the steerable wheels;
an input shaft coupled to the power source;
an output shaft connected to a support member that supports the steered wheels;
a linear motion guide that guides the linear motion of the output shaft with respect to the input shaft;
a universal joint disposed between the input shaft and the output shaft and supporting the output shaft through the linear motion guide so as to be swingable;
a spring interposed between the linear motion guide and the output shaft or the support member;
The linear motion guide part supports the output shaft so as to be linearly movable and torque transmissible while being arranged in the vicinity of the universal joint. 2. The steering system according to claim 1, wherein at least part of said linear motion guide portion is accommodated within said universal joint. The universal joint is flat as a whole,
an annular inner frame;
an annular intermediate frame disposed outside the inner frame and rotatably supporting the inner frame with the first direction as a rotation axis;
an annular outer frame disposed outside the intermediate frame and rotatably supporting the intermediate frame with a rotation axis in a second direction perpendicular to the first direction;
The input shaft is connected to one of the inner frame body and the outer frame body,
The steering system according to claim 1 or 2, wherein the linear guide portion is connected to the other of the inner frame body and the outer frame body. The steering system according to any one of claims 1 to 3, which is used in the vehicle equipped with a strut-type suspension mechanism.

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