JP2011131801A - Bell crank arm structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device for improving operability and durability, by enhancing rigidity of a link mechanism of steering, by reducing stress generated in an installation bracket to the vehicle side for supporting a rotary shaft of a bell crank. <P>SOLUTION: A bell crank 3 mechanism is arranged in an intermediate part of the link mechanism 2 of the steering of a vehicle. This bell crank arm structure include an arm shaft 33 arranged in the vertical direction, an input side crank arm 31 having one end fixed to an upper end part of the arm shaft 33 and having the other end pivoted on a drag link 4 rocking in the longitudinal direction of the vehicle by being displaced downward, and an output side crank arm 32 having one end fixed to a lower end part of the arm shaft 33 and having the other end pivoted on a relay rod 51 rocking in the lateral direction of the vehicle by being displaced upward, and the respective other end intervals of the input side crank arm 31 and the output side crank arm 32 are shortened more than the length of the arm shaft 33 in the vertical direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a link mechanism that transmits steering force to a vehicle wheel.

A steering mechanism of a vehicle transmits steering of a steering wheel disposed in a driver's seat to wheels by a link mechanism, and moves the vehicle in an arbitrary direction by a driver's operation.
However, when the vehicle weight increases with the increase in vehicle equipment, and the turning angle is narrow, there is a so-called stationary operation in which the steering wheel is operated to the maximum when the vehicle is stopped. The need to increase power has arisen. The steering force of the steering wheel can reduce the burden on the driver by increasing the assist force of the power steering.
However, a reaction force due to frictional resistance between the wheel and the road surface acts on the steering link mechanism against the steering force for steering the wheel. The steering of the wheel is maintained by the reaction force by the rigidity of the link mechanism.

In particular, as shown in FIG. 4 (A), a bell crank 110 (corresponding to reference numeral 3 in FIG. 1) for converting the vehicle's forward / backward swing to left / right swing is provided at the intermediate portion of the link mechanism. Is arranged. In the bell crank 110, a relay rod 114 is connected to an input side crank arm 111 that receives a steering force from the steering wheel side and an output side crank arm 112 that steers the wheel side via an arm shaft 113. A tie rod is connected to both ends of the relay rod 114, and a wheel is disposed at the tip of the knuckle for steering the wheel. Torsional force and bending force are generated in the bell crank 110 due to the reaction force from the side of the wheel to be steered, and the load due to twisting is applied to the Y portion of the arm shaft 113 of the bell crank 110 and the arm bracket 115 supporting the arm shaft 113. It has been found that a high value is generated in terms of stress.
As for the location, high stress is generated in the Y portion (FIG. 4B) in the direction of the arrow Z (FIG. 4A) of the arm bracket 115 for attaching the bell crank 110 to the vehicle body.

This is a shape in which the connecting portion of the output side crank arm 112 and the relay rod 114 is offset downward.
Therefore, since the reaction force due to the frictional resistance between the wheel and the road surface is below the lower end of the arm shaft 113, the arm shaft 113 is easily arranged to bend in the axial direction of the arm shaft 113.
Japanese Patent Laid-Open No. 5-345511 (Patent Document 1) is disclosed as a prior art document of similar technology.

Japanese Patent Laid-Open No. 5-345511

And in patent document 1, the connection part with the actuator of the input side crank arm which is arrange | positioned at the upper end part of the rotating shaft of a bell crank and is an input side to a bell crank is offset upwards. An output-side crank arm that is an output side connected to a tie rod that transmits a steering force to a wheel is disposed at the lower end portion of the rotating shaft of the bell crank.
Therefore, the vertical height of the input unit and the output unit is higher than the vertical height of the rotating shaft. According to this structure, the bending force acting on the rotating shaft of the bell crank is greater than the force directly input from the actuator to the shaft end portion of the rotating shaft.
Accordingly, there is a problem in that a large stress is generated in the bearing portions arranged above and below to support the rotating shaft and the mounting bracket on the vehicle side that supports the bearing portions.

  The present invention has been made to solve such problems. The crankshaft rotation shaft is elongated and the crank arm input side connecting portion and the crank arm output attached to the upper and lower ends of the rotation shaft, respectively. Occurs in the bearing part that rotatably supports the rotation axis of the bell crank and the mounting bracket on the vehicle side that supports the bearing part by making the vertical distance between the side coupling parts smaller than the distance between the upper and lower ends of the rotation axis It is an object of the present invention to provide a bell crank arm structure for a steering device that improves operability and durability by reducing the stress to be applied and increasing the rigidity of the steering link mechanism.

  The present invention achieves such an object, and is arranged at an intermediate portion of a link mechanism for transmitting a steering force to a vehicle wheel, and converts a longitudinal swing of the vehicle into a lateral swing. In the arm structure, an arm shaft arranged in the vertical direction of the vehicle, an arm bracket that pivotally supports the arm shaft around a vertical axis and is fixed to a chassis frame, and one end of the arm shaft. A first crank arm fixed to the upper end, the other end being displaced downward, and pivotally attached to a drag link swinging in the longitudinal direction of the vehicle at the displaced position, and one end at the lower end of the arm shaft And a second crank arm pivotally attached to a relay rod that swings in the left-right direction of the vehicle at the displaced position. In the direction, characterized in that between the other end of each of said first crank arm and said second crank arm is made shorter than the length of the arm shaft.

  With such a configuration, the position of the steering force input to the first crank arm from the drag link side with respect to the mounting position of the first crank arm and the second crank arm fixed to the arm shaft, and the relay rod Since the position of the reaction force accompanying the wheel steering input from the side to the second crank arm is close to the middle part of the arm shaft in the vertical direction, the arm shaft and the bearing part that supports the arm shaft and The bending stress generated in the arm bracket can be reduced

Preferably, in the invention of the present application, at least one of the crank arms is provided in the inclined portion that is displaced downward in the first crank arm and in the vertical direction of the second crank arm, and at least the upper surface or the lower surface of the crank arm. Any surface may be formed with a lightening recess for weight reduction along an inclination, and the inclined lower surface of the recess may be formed substantially horizontally so that rainwater does not collect.

With such a configuration, the weight can be reduced, the amount of material used due to the lightening groove can be reduced, and the cost can be reduced.
Further, it is possible to enhance the rust prevention effect of the first crank arm and the second crank arm by preventing mud or rain water from collecting in the groove.

  The position of the steering force input to the first crank arm from the drag link side with respect to the mounting position of the first crank arm and the second crank arm fixed to the arm shaft, and the second crank arm from the relay rod side Since the position of the reaction input to the center of the arm shaft is close to the middle part in the vertical direction of the arm shaft, it occurs in the bearing part that rotatably supports the rotating shaft of the bell crank and the mounting bracket on the vehicle side that supports the bearing part. The operability and durability can be improved by reducing the stress to increase the rigidity of the steering link mechanism.

The top view which shows the steering mechanism outline of the vehicle which concerns on embodiment of this invention is shown. In the bell crank according to the embodiment of the present invention, (A) is a perspective view of the whole bell crank, and (B) is a side view of the input side crank arm. The assembly state figure of the arm shaft and arm bracket concerning the embodiment of the present invention is shown. In the bell crank according to the conventional example, (A) is a perspective view of the whole bell crank, and (B) is a Z arrow view of (A) of a single arm bracket.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this example are not intended to limit the scope of the present invention only to specific examples unless otherwise specified. Only.

(First embodiment)
FIG. 1 shows a front portion of a vehicle 1, and a steering link mechanism 2 for steering the front wheels 10 is arranged. A bone frame 11, which is a part of a chassis frame (not shown) of the vehicle 1, is disposed at the front portion of the vehicle 1 at the center of the vehicle 1 in the vehicle width direction.
The bone frame 11 also extends in the vertical direction, is formed in a box shape with a closed cross section, and arms 7 of independent suspension type suspensions are pivotally mounted on both side surfaces so as to be rotatable in the vertical direction.
A knuckle 8 is fixed to the outside of the arm 7 in the vehicle width direction, and a front wheel 10 is attached to a knuckle spindle (not shown) protruding from the knuckle 8 to the outside of the vehicle width via a hub bearing.
An arm having substantially the same shape as the arm 7 is also disposed below the bone frame 11 so that the knuckle 8 disposed in the vertical direction can be translated in the vertical direction.

The steering wheel steering (not shown) is transmitted to a drag link 4 connected to a pitman arm (not shown) mounted on a steering gear box (not shown). The steering gear box incorporates a power steering that reduces the operating force of the steering wheel.
The pitman arm is a member for switching the rotation operation of the steering wheel to swing the steering gear box in the vehicle front-rear direction.

As shown in FIG. 2A, the bell crank 3 has an axial center disposed in the vertical direction of the vehicle 1, and an arm shaft 33 that rotates about the axial center. An arm bracket that is pivotally supported and attached to a chassis frame (not shown), one end fixed to the upper end of the arm shaft 33, the other end extending in the radial direction of the arm shaft 33, and swinging in the vehicle longitudinal direction. The first crank arm that is offset downward and pivotally attached to the drag link 4, one of which is fixed to the lower end portion of the arm shaft 33, the other extending in the radial direction of the arm shaft 33, The input side crank arm 31 and the circumferential phase are shifted by 90 °, swing in the vehicle width direction, and offset upward so that the relay rod 51 And an output-side crank arm 32 is a second crank arm pivotally mounted.
One end of the tie rod 5 is pivotally attached to both ends in the vehicle width direction of the relay rod 51 pivotally attached to the output side crank arm 32, and the other end of the tie rod 5 is pivotally attached to the knuckle arm 6 connected to the knuckle 8. ing.
Further, as shown in FIG. 2B, a weight reducing groove 37 is provided on the upper inclined portion of the input side crank arm 31. The groove 37 is substantially horizontal on the lower surface side of the inclined portion, so that rainwater, mud and the like are not collected, and an antirust effect is obtained.
It should be noted that the lightening groove 37 is not limited to the upper surface of the input-side crank arm 31 but may be provided on the lower surface, and may be provided on the output-side crank arm 32 as necessary.

The operation of the steering link mechanism 2 will be described.
In FIG. 1, when the steering is operated to the right, the drag link 4 moves upward (rear of the vehicle). The bell crank 3 rotates clockwise around the arm shaft 33, and the relay rod 51 moves to the left (right side in FIG. 1). When the relay rod 51 moves to the left, the tie rod 5 moves to the left, and the knuckle arm 6 rotates about the king pin 61 in the clockwise direction. When the knuckle arm 6 rotates, the front wheel 10 attached to the knuckle spindle formed integrally with the knuckle arm 6 rotates to the right (left side in FIG. 1). When the steering is operated to the left, the above operation is reversed.

In the above-described operation, when the vehicle 1 is traveling, the front wheel 10 rotates while rotating, so that the reaction force (resistance) from the front wheel 10 is small. However, in the case of stationary driving (steering operation when the vehicle is stopped), the friction resistance between the road surface and the rubber tire of the front wheel is large, and the reaction force is applied to the input side crank via the knuckle arm 6, tie rod 5 and relay rod 51. Acts on the arm 31. On the other hand, a handle operating force is input from the drag link 4 side. An acting force in the vehicle width direction and an acting force in the vehicle front-rear direction act on the bell crank 3, and an acting force (bending force) in a direction tilting with respect to the vertical axis is applied to the arm shaft 33.
However, the vertical distance between the connecting portion of the input side crank arm 31 to the drag link 4 and the connecting portion of the output side crank arm 32 to the relay rod 51 is set to the upper and lower ends of the arm shaft 33. Since it is smaller than the distance between one end of the crank arm 31 and one of the output side crank arms 32, the moment force in the bending direction acting on the upper and lower ends of the arm shaft 33 becomes smaller than the lever ratio and is generated in the arm bracket 35. Stress to be reduced.

(Second Embodiment)
Since the basic structure is the same as that of the first embodiment, only different parts will be described.
In FIG. 2, instead of the output side crank arm 32 of the bell crank 9, an output side crank arm 92 in which the material of the conventional output side crank arm 112 is turned upside down is created, and the arm shaft 91 is extended downward. The vertical coupling position with the relay rod 51 is the same as the position of the conventional relay rod 51.
As a result, as shown in FIG. 3, the mounting pitch L of the bearing 34 in the axial direction of the arm shaft 91 can be made twice as long as the offset amount between the one side and the other side of the output side crank arm 92.

Thus, the coupling position of the output side crank arm 92 with the relay rod 51 is above the lower end portion of the arm shaft 91 and the vertical direction of the arm shaft 91 is also longer, so that it acts on the upper and lower end portions of the arm shaft 33. The bending force becomes smaller than the lever ratio, and the stress generated in the arm bracket 93 can be reduced.
In addition, since the vertical coupling position with the relay rod 51 is the same as the conventional position, a conventional link mechanism other than the bell crank 9 can be used by simply changing the bell crank 9, and the cost increase is minimized. Can be suppressed.

  A steering device that improves operability and durability by increasing the rigidity of the steering mechanism with a bell crank in the link mechanism.

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Link mechanism 3, 9 Bell crank 4 Drag link 5 Tie rod 6 Knuckle arm 31 Input side crank arm 32, 92 Output side crank arm 33, 91 Arm shaft 51 Relay rod

Claims (2)

  In a bell crank arm structure that is disposed at an intermediate portion of a link mechanism that transmits a steering force of a steering wheel to a vehicle wheel, and that converts the longitudinal swing of the vehicle into a lateral swing, it is disposed in the vertical direction of the vehicle. An arm shaft, an arm bracket that is pivotally supported about a vertical axis and fixed to the chassis frame, one end is fixed to the upper end of the arm shaft, and the other end is downward. A first crank arm pivotally attached to a drag link that swings in the longitudinal direction of the vehicle at the displaced position, and one end fixed to the lower end portion of the arm shaft and the other end displaced upward. A second crank arm pivotally attached to a relay rod that swings in the left-right direction of the vehicle at the displaced position, and in the up-down direction, the first crank arm Bell crank arm structure, characterized in that each between the other end of shorter than the length of the arm shaft and the second crank arm and.   At least one of the crank arms is inclined at the inclined portion of the first crank arm that is displaced in the vertical direction of the second crank arm, and at least one of the upper and lower surfaces of the crank arm is inclined. 3. A lightening recessed portion for reducing weight is formed along the inclined lower surface of the recessed portion so as to prevent rainwater from accumulating. Bell crank arm structure.

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