JP2006143013A - Steering retention force adjusting mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering retention force adjusting mechanism for restraining the deviation of a vehicle by adjusting the steering retention force in rectilinear movement. <P>SOLUTION: A suspension structure has a fulcrum 5a of a stabilizer in a shock absorber also serving as a strut fixed to a king pin shaft K. The stabilizer 6 is connected to the fulcrum 5a by a stabilizer link 5, and the stabilizer link 5 adjusts its total length by a length adjusting mechanism 52. The length of the stabilizer link 5 is adjusted to thereby adjust the moment (arrow B) of a stabilizer reaction force reverse to the moment (arrow A) around the king link axis generated by a road surface cant to cancel the moment. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mechanism that adjusts the steering force that affects the straight traveling performance when the vehicle travels, and more particularly, to a steering force adjustment mechanism that is configured to be able to adjust the steering force using a stabilizer reaction force.

  The road surface on which the vehicle travels is not flat in the cross-sectional direction, and has a cross slope that is higher in the center than at both ends. Due to the lateral component of the axle load due to the road surface gradient, a moment is generated around the kingpin axis of the suspension, and a slip angle is generated in the tire to balance it, so if the driver does not hold the steering wheel, the vehicle However, a vehicle flow that naturally deviates from the straight traveling direction to the lateral direction is generated, and in order to maintain the straight traveling, the driver must hold the steering wheel with a predetermined holding force.

On the other hand, a technique is known that suppresses the flow of the vehicle and reduces the steering force when traveling straight by adding a predetermined residual lateral force to the tire according to the crossing gradient of the road surface (for example, , See Patent Document 1).
Japanese Patent Laid-Open No. 11-115418

  However, due to the difference in the residual lateral force due to the tire tolerance and the difference in the vehicle flow caused by the steering system tolerance and the left / right difference due to the alignment tolerance, the actual lateral flow is excessive or insufficient. There is a possibility that the suppression will be insufficient or a reverse vehicle flow may occur. In addition, when the vehicle is used under different road crossing gradients, tire replacement is required.

  Then, this invention makes it a subject to provide the steering force adjustment mechanism which can adjust the steering force at the time of going straight, and suppresses a vehicle flow.

  In order to solve the above-mentioned problems, a steering force adjusting mechanism according to the present invention has a suspension structure having a fulcrum of a stabilizer at a portion fixed to a kingpin shaft, and a stabilizer link configured to be independently adjustable in length on the left and right. The steering force can be adjusted by adjusting the left and right stabilizer reaction force balance by adjusting the length of the stabilizer link.

  By changing the length of the left and right stabilizer links, the moment generated by the stabilizer reaction force in each of the left and right suspensions can be adjusted. The steering holding force is adjusted by canceling out the moment generated by the road crossing gradient by the moment generated by the stabilizer reaction force.

  Alternatively, the steering holding force adjusting mechanism according to the present invention has a suspension structure having a fulcrum of the stabilizer at a portion fixed to the kingpin shaft, and the stabilizer link mounting position on the suspension side is shifted to the left and right in a direction crossing the stabilizer reaction force direction. In this case, the steering holding force can be adjusted by making it independently adjustable.

  By changing the crossing position of the stabilizer link, the distance between the point of action of the stabilizer reaction force and the kingpin shaft is changed to change the moment arm length. As a result, the moment generated by the stabilizer reaction force is adjusted, and the steering holding force can be adjusted.

  Alternatively, the steering force adjusting mechanism according to the present invention has a suspension structure having a stabilizer fulcrum at a portion fixed to the kingpin shaft and having an active stabilizer, so that the actual lateral vehicle flow with respect to steering can be obtained. Means for determining and means for independently adjusting the drive amount of the active stabilizer on the left and right sides of the vehicle so as to cancel the vehicle flow in the lateral direction during the straight traveling operation may be provided.

  The steering force is adjusted by adjusting the drive amount of the active stabilizer to adjust the moment generated by the stabilizer reaction force.

  By adjusting the moment generated by the stabilizer reaction force and offsetting it with the moment generated by the road gradient, the vehicle flow during non-steering is suppressed to improve straightness, and the steering force during straight steering is reduced. be able to. In addition, fine adjustment is possible according to vehicle characteristics (for example, characteristics of mounted tires and steering system characteristics) and road characteristics, which is useful for improving maneuverability and vehicle controllability.

  In particular, if an active stabilizer is used to cancel the moment generated by the road crossing gradient, automatic adjustment can be performed according to vehicle characteristics and road characteristics. It becomes easy to maintain the rudder force at substantially zero.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same reference numerals are given to the same components in the drawings as much as possible, and duplicate descriptions are omitted.

  FIG. 1 is a configuration diagram showing a suspension structure having a first embodiment of a steering holding force adjusting mechanism according to the present invention. This suspension is a McPherson strut type front wheel suspension having an L-shaped lower arm 1, and the figure shows the right front wheel.

  As shown in FIG. 1, a shock absorber 3 is fixed to an upper part of a spindle 2 to which a wheel is attached, and one end of a lower arm 1 is connected to a lower part by a ball joint 20. The shock absorber 3 also serves as a strut, and a coil spring 42 sandwiched between an upper seat 40 and a lower seat 41 is disposed around the upper portion of the shock absorber 3. The upper end 30 of the shock absorber 3 is connected to the vehicle body via an insulator or the like (not shown). A stabilizer link 5 is attached slightly below the lower seat 41 of the shock absorber 3, and one end of the stabilizer 6 is connected to the other end.

  Thereby, the fulcrum of the stabilizer 6 (the upper end 5a of the stabilizer link 5 in FIG. 1) is fixed to the kingpin axis K (the axis connecting the upper end 30 of the shock absorber 3 and the ball joint 20). The other end of the stabilizer 6 is connected to the lower end of the left front wheel stabilizer link 5 (not shown).

  Here, the stabilizer link 5 is obtained by connecting an upper link 50 and a lower link 51 by a length adjusting mechanism 52. For example, the length adjusting mechanism 52 is configured such that the lower part can roll with the longitudinal direction as a rotation axis with respect to the upper part, and the screwing amount of the screw connection with the upper part of the lower link 51 or the lower part of the upper link 50 is changed. Thus, the entire length may be adjusted.

In the suspension system as shown in FIG. 1, a moment M _K indicated by an arrow A is generated around the kingpin axis K due to a road surface crossing gradient (road surface cant) (see FIG. 2). This M _K is expressed by the following equation (1).

Here, STD, LFD is of uniformity of the tire, respectively, a steering torque Deviation, lateral force Deviation, K _y is cornering stiffness, A _s is aligning stiffness, alpha slip angle, e ₁ is mechanical Trail (distance between the intersection of the kingpin axis K and the road surface), W is a tire load, and θ is a road surface cant.

On the other hand, the force (stabilizer reaction force) acting by the stabilizer 6 is F _st , and this stabilizer reaction force line is S. In the present embodiment, S coincides with the longitudinal direction of the stabilizer link 5. As shown in FIG. 3, when the distance between S and the kingpin axis K is l _st and the slope of S with respect to K is φ, the moment M _st (arrow B in FIG. 1) generated by the stabilizer reaction force is It is given by the following equation (2).

When the length of the stabilizer link 5 is adjusted, the direction of the stabilizer reaction force line S changes. Thereby, since φ and lst change, the moment M _st can be changed.

  Here, in order for the vehicle to go straight, the following equation (3) needs to be satisfied.

If the length of the stabilizer link 5 is adjusted and M _st is adjusted so that M _K + M _{st ≈0 at} the slip angle α where the equation (3) is established, the driver does not hold the steering wheel. Even in the state where force = 0, it is possible to ensure the straightness of the vehicle. As the road surface cant θ at the time of this adjustment, a general road surface cant under the use environment of the vehicle may be used.

  It should be noted that when adjusting the actual stabilizer link, it is not always necessary to theoretically adjust using the equations (1) to (3). For example, when a vehicle flow occurs, the stabilizer is reduced in the direction to reduce it. Adjustments may be made so that the vehicle flow or the steering force is less than or equal to a predetermined threshold by repeating fine adjustment of the length of the link 5.

  According to the present embodiment, by adjusting the length of the stabilizer link 5 in this way, the steering force can be adjusted and the vehicle flow can be suppressed. The difference in the steering force generated based on the alignment state or the like can be absorbed, and the steering force can be reduced by reliably suppressing the vehicle flow. Further, even when used in an environment where the road surface cant is different, the adjustment can be performed without replacing the tire.

  FIG. 4 is a configuration diagram showing a suspension structure having the second embodiment of the steering force adjusting mechanism according to the present invention. The basic structure of this suspension structure is the same as that of the first embodiment shown in FIG.

  This embodiment is different from the first embodiment shown in FIG. 1 in the attachment portion of the stabilizer link 5 and the shock absorber 3. Specifically, in the present embodiment, a link attachment portion 7 extending from the shock absorber 3 in a substantially horizontal direction (direction intersecting with the kingpin axis K) is provided, and the link attachment portion 7 has a groove 70 in the extending direction. Is formed. Thereby, the attachment position to the link attaching part 7 of the stabilizer link 5 can be shifted in a horizontal direction.

As described above, when the link attaching portion 7 of the stabilizer link 5 is shifted in the horizontal direction, the distance between the stabilizer reaction force line S and the kingpin axis K can be greatly changed. As a result, the amount of change in the moment length lst in equation (2) can be increased, so that the adjustment range of the moment Mst due to the stabilizer reaction force can be increased. As a result, the same effects as those of the first embodiment can be obtained, and even when the moment M _K due to the road surface cant is large, it is possible to cope with it. At this time, the length of the stabilizer link 5 may be adjusted to match.

  FIG. 5 is a configuration diagram showing a suspension structure having the third embodiment of the steering force adjusting mechanism according to the present invention. The basic structure of this suspension structure is the same as that of the first embodiment shown in FIG. 1 and the second embodiment shown in FIG.

  This embodiment differs from the first embodiment shown in FIG. 1 in the configuration of the stabilizer link 5 and the stabilizer 6. In this embodiment, the stabilizer link 5 is a non-expandable type having a fixed length, and the stabilizer 6 is twisted by rotation of the actuator 65 by connecting the actuator 65 to the stabilizer 6. 5 is used to transmit the stabilizer reaction force to the motor. The stabilizer reaction force can be freely set by the actuator 65.

FIG. 6 is a block diagram of the control unit of the present embodiment. A control unit ECU68 is, CPU, ROM, it is constituted by a RAM or the like, to change freely Sutarabiraiza reaction force _{F st} by controlling the drive amount of the actuator 65. The ECU 68 is provided with an output signal of a steering torque sensor 66 that is disposed on a steering wheel and a steering shaft (not shown) and detects a steering amount by a driver, and a yaw rate sensor 67 that detects a yaw rate generated in the vehicle. ing.

In the present embodiment, by providing the stabilizer reaction force F _st ECU 68 based on the output signal of the steering torque sensor 66 and the yaw rate sensor 67 controls the actuator 65, as is clear from equation (2), moment M _st is changed and control is performed so as to cancel the moment M _K caused by the road surface cant.

  FIG. 7 is a diagram showing the relationship between the steering torque and the yaw rate in the present embodiment. When the driver does not operate the steering wheel when the vehicle flows, so-called letting go, the steering torque becomes zero, but a yaw rate corresponding to the vehicle flow is generated. On the other hand, when the steering torque is not 0 even though the yaw rate is 0, the vehicle is in a straight traveling holding state where the vehicle flow is suppressed by the holding force. In the present embodiment, the stabilizer reaction force applied by the actuator 65 is adjusted so that the yaw rate corresponding to the steering torque is generated, thereby realizing the target steering torque-yaw rate. For this control, feedback control, feedforward control, PID control, or a combination thereof can be used.

  According to the present embodiment, the road surface cant can be surely and automatically canceled regardless of the tire characteristics or the steering system characteristics. Accordingly, it is possible to cope with changes due to different conditions of the road surface, tire characteristics, steering characteristics, etc., so that straightness can be improved and maintained.

  Here, an example in which the driving amount of the actuator 65 is automatically controlled has been described, but the driver can manually set the driving amount in a stepwise or stepless manner by using a switch, a slider, or the like. The adjustment may be made by If the lateral flow of the vehicle can be determined, the vehicle state quantity used for the determination is not limited to the combination of the yaw rate and the steering torque. For example, the lateral acceleration may be used instead of the yaw rate, and the steering angle may be used instead of the steering torque. .

  In the above description, the suspension structure having the fulcrum of the stabilizer 6 on the shock absorber 3 (functioning as a strut) has been described. However, the present invention is not limited to this, and a portion fixed to the kingpin shaft, for example, a knuckle The present invention can also be applied to a suspension having a structure having a fulcrum of the stabilizer.

It is a block diagram which shows the suspension structure which has 1st Embodiment of the steering force adjustment mechanism concerning this invention. It is a diagram illustrating a moment M _K generated in the kingpin axis K direction by the road cross slope (road surface cant). It is a figure which shows the relationship between the position of a stabilizer reaction force line, the kingpin axis | shaft, and a moment. It is a block diagram which shows the suspension structure which has 2nd Embodiment of the steering force adjustment mechanism concerning this invention. It is a block diagram which shows the suspension structure which has 3rd Embodiment of the steering force adjusting mechanism concerning this invention. It is a block diagram of the control part of the steering force adjustment mechanism of FIG. It is a figure which shows the relationship between the steering torque and yaw rate in 3rd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Lower arm, 2 ... Spindle, 3 ... Shock absorber, 5 ... Stabilizer link, 5a ... Upper end of stabilizer link (stabilizer fulcrum), 6 ... Stabilizer, 7 ... part, 20 ... Ball joint, 30 ... Upper end of shock absorber, 40 ... Upper seat, 41 ... Lower seat, 42 ... Coil spring, 50 ... Upper link, 51 ... Lower link, 52 ... Length adjusting mechanism, 65 ... Actuator, 66 ... Steering torque sensor, 67 ... Yaw rate sensor, 68 ... ECU, 70: Groove.

Claims (3)

  It has a suspension structure that has a stabilizer fulcrum at the part fixed to the kingpin shaft, and is equipped with a stabilizer link that can be adjusted in length independently on the left and right, and by adjusting the length of the stabilizer link, A steering force adjusting mechanism characterized in that the steering force can be adjusted by adjusting the stabilizer reaction force balance.   It has a suspension structure that has a stabilizer fulcrum at the part fixed to the kingpin shaft, and the stabilizer link mounting position on the suspension side can be adjusted independently on the left and right in the direction crossing the direction of the stabilizer reaction force. A steering holding force adjusting mechanism characterized in that the force can be adjusted. It has a suspension structure that has a stabilizer fulcrum at the part fixed to the kingpin shaft and is equipped with an active stabilizer.
Means for determining the actual lateral vehicle flow relative to steering;
Means for independently adjusting the drive amount of the active stabilizer on the left and right sides of the vehicle so as to cancel the vehicle flow in the lateral direction during the straight traveling operation;
A steering holding force adjusting mechanism characterized by comprising:

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