JP2007132815A - Wheel longitudinal force calculating device and lateral force calculating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely calculate a longitudinal force and a lateral force of a wheel with a simple structure. <P>SOLUTION: Longitudinal acceleration XG parallel to a rotation surface of the wheel and lateral acceleration YG to orthogonal to the rotation surface of the wheel are detected by a longitudinal acceleration sensor and a lateral acceleration sensor provided in a spring lower member having a knuckle shape. A longitudinal force FX parallel to a movement direction and a lateral force FY orthogonal to the movement direction are respectively calculated by the formulas, FX=K×(XG×cos β+YG×sin β) and FY=K×(YG×cos β+XG×sin β). However, β is a slip angle of the wheel and expressed by the formula of β=tan<SP>-1</SP>(∫YG/∫XG). Where K is a coefficient of a vehicle wheel ground load. In the longitudinal acceleration sensor and the lateral acceleration sensor, restrictions in a mounting method and a mounting position thereof are negligible unlike a distortion sensor. Accordingly, machining for mounting thereof will not reduce the strength of a spring lower member. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention calculates a longitudinal force calculation device for a wheel that calculates a longitudinal force FX acting on a wheel suspended from a vehicle body via a suspension device, and a lateral force FY that acts on a wheel suspended from the vehicle body via a suspension device. The present invention relates to a wheel lateral force calculation device.

  Conventionally, in order to detect a load applied to a wheel of a traveling vehicle (a longitudinal force in a direction parallel to the wheel rotation surface and a lateral force in a direction perpendicular to the wheel rotation surface), There are known a technique for detecting the strain of the hub bearing with a strain sensor, and a technique for detecting the phase change of the magnetized portion due to the multi-polar magnetic attachment on the tire sidewall and the deformation of the tire.

  However, in the former method, not only the mounting position of the strain sensor is greatly restricted in order to detect strain in a desired direction, but also the strength of the wheel and hub bearing is required because the mounting hole of the strain sensor must be processed. There has been a problem that a reduction is required, and a special technique is required for the joint that transmits the generated strain to the strain sensor. In addition, the latter method has a problem that it has poor versatility because a special tire needs to be used.

  The present invention has been made in view of the above circumstances, and an object thereof is to accurately calculate the longitudinal force and lateral force of a wheel with a simple structure.

In order to achieve the above object, according to the first aspect of the present invention, a longitudinal force calculation device for a wheel that calculates a longitudinal force FX parallel to a traveling direction acting on a wheel suspended from a vehicle body via a suspension device. A longitudinal acceleration sensor for detecting longitudinal acceleration XG parallel to the rotational surface of the wheel and a lateral acceleration sensor for detecting lateral acceleration YG orthogonal to the rotational surface of the wheel on an unsprung member that rotatably supports the wheel. And using the coefficient K indicating the longitudinal acceleration XG, the lateral acceleration YG and the wheel contact load,
FX = K × (XG × cos β + YG × sin β)
Where β is the slip angle of the wheel and β = tan ⁻¹ (∫YG / ∫XG)
A device for calculating the longitudinal force of a wheel is proposed.

According to a second aspect of the present invention, there is provided a wheel lateral force calculating device for calculating a lateral force FY perpendicular to a traveling direction acting on a wheel suspended from a vehicle body via a suspension device, the wheel rotating the wheel. The unsprung member that is freely supported is provided with a longitudinal acceleration sensor for detecting longitudinal acceleration XG parallel to the rotational surface of the wheel and a lateral acceleration sensor for detecting lateral acceleration YG orthogonal to the rotational surface of the wheel, and the lateral force FY is calculated using the longitudinal acceleration XG, the lateral acceleration YG, and the coefficient K indicating the wheel contact load.
FY = K × (YG × cos β + XG × sin β)
Where β is the slip angle of the wheel and β = tan ⁻¹ (∫YG / ∫XG)
A wheel lateral force calculating device is proposed, which is characterized by the following calculation.

  In addition, the knuckle 13 of an Example respond | corresponds to the unsprung member of this invention.

  According to the above configuration, the unsprung member that rotatably supports the wheel, the longitudinal acceleration sensor that detects the longitudinal acceleration XG parallel to the rotation surface of the wheel, and the lateral acceleration YG that is orthogonal to the rotation surface of the wheel. With a simple structure that only provides an acceleration sensor, the longitudinal force FX acting parallel to the traveling direction acting on the wheel and the lateral force FY acting on the wheel perpendicular to the traveling direction are accurately taken into account with respect to the slip angle of the wheel. Can be calculated. In addition, since the longitudinal acceleration sensor and the lateral acceleration sensor are different from the strain sensor in terms of attachment method and attachment position, the strength of the unsprung member is not impaired by the processing for attachment. In addition, since a special tire that is magnetically poled on the side wall is not required, it can be applied to any wheel and the versatility is improved.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples of the present invention shown in the accompanying drawings.

  1 to 3 show an embodiment of the present invention. FIG. 1 is a perspective view of a double wishbone suspension of a left rear wheel, FIG. 2 is a view taken in the direction of the arrow in FIG. 1, and FIG. It is explanatory drawing of the longitudinal force and lateral force which are added to.

  As shown in FIGS. 1 and 2, the double wishbone suspension device S includes a knuckle 13 supported by the vehicle body by an upper arm 11 and a lower arm 12. The knuckle 13 includes a knuckle body 14 and a lower arm support bracket 15 fastened to the lower part thereof. The knuckle body 14 includes an axle support portion 14a that rotatably supports the axle of the wheel W, and an upper arm support portion 14b that extends upward from the axle support portion 14a, and a ball joint at the upper end of the upper arm support portion 14b. 16, the outer end of the upper arm 11 in the vehicle width direction is pivotally supported. The outer end in the vehicle width direction of the lower arm 12 is pivotally supported by a ball joint 19 fixed to a lower arm support bracket 15 fastened to the lower part of the knuckle body 14 by bolts 17 and 18. The vicinity of the outer end in the vehicle width direction of the lower arm 12 and the vehicle body are connected by a damper 20 including a hydraulic cylinder and a suspension spring arranged coaxially.

  A longitudinal acceleration sensor 21 and a lateral acceleration sensor 22 are provided on the knuckle 13 which is an unsprung member of the suspension device S. The longitudinal acceleration sensor 21 detects longitudinal acceleration (longitudinal acceleration XG) parallel to the rotating surface of the wheel W, and the lateral acceleration sensor 22 detects lateral acceleration (lateral acceleration YG) orthogonal to the rotating surface of the wheel W. To do. Since the longitudinal acceleration sensor 21 and the lateral acceleration sensor 22 are small in size, for example, the wheel speed sensor can be supported by an attachment member attached to the knuckle 13.

As shown in FIG. 3, when the orthogonal coordinate system fixed to the wheel W is an XY coordinate system, the longitudinal acceleration XG detected by the longitudinal acceleration sensor 21 is the acceleration in the X direction of the XY coordinate system, and the lateral acceleration. The lateral acceleration YG detected by the sensor 22 is the acceleration in the Y direction of the XY coordinate system. The traveling direction of the wheel W (the traveling direction of the vehicle) does not necessarily coincide with the X direction of the XY coordinate system, and the angle formed by the traveling direction of the wheel W and the X direction is the slip angle β. That is, when the velocity in the X direction is u and the velocity in the Y direction is v, the slip angle β is
β = tan ⁻¹ (v / u)
Given in.

  In the present invention, based on the longitudinal acceleration XG and the lateral acceleration YG detected by the longitudinal acceleration sensor 21 and the lateral acceleration sensor 22, the longitudinal force FX, which is the force in the traveling direction applied to the wheel W, is orthogonal to the traveling direction applied to the wheel W. A lateral force FY, which is a directional force, is calculated.

When the longitudinal acceleration XG is integrated, the velocity u in the X direction is obtained, and when the lateral acceleration YG is integrated, the velocity v in the Y direction is obtained.
β = tan ⁻¹ (v / u) = tan ⁻¹ (∫YG / ∫XG)
Given in.

m is a set value of the ground contact load of the wheel W in the initial state, c is a correction coefficient corresponding to a change in suspension stroke determined from a detection value of a suspension stroke sensor (not shown) (1 in the initial state, 1 on the bump side of the suspension) Larger, and a positive value smaller than 1 on the rebound side of the suspension)
K = m × c
Given in. Therefore, the longitudinal force FX, which is the force in the traveling direction applied to the wheel W, is
FX = K × (XG × cos β + YG × sin β)
The lateral force FY, which is a lateral force applied to the wheel W, is given by
FY = K × (YG × cos β + XG × sin β)
Given in.

  As described above, the knuckle 13, which is an unsprung member that rotatably supports the wheel W, has an inexpensive and simple structure in which the longitudinal acceleration sensor 21 and the lateral acceleration sensor 22 are provided, and is parallel to the traveling direction acting on the wheel W. The longitudinal force FX and the lateral force FY perpendicular to the traveling direction acting on the wheel W can be accurately calculated in consideration of the wheel slip angle β. In addition, the longitudinal acceleration sensor 21 and the lateral acceleration sensor 22 are different from the conventionally used strain sensors in that there are few restrictions on the mounting method and mounting position, so that it can be mounted at an appropriate position by an appropriate method. In this process, the strength of the knuckle 13 is not impaired. In addition, since it does not require special tires that are magnetically poled on the side walls or special wheels with strain sensors embedded, it can be applied to any type of wheel, improving versatility.

  Although the embodiments of the present invention have been described above, various design changes can be made without departing from the scope of the present invention.

  For example, in the embodiment, the knuckle 13 is employed as the unsprung member to which the longitudinal acceleration sensor 21 and the lateral acceleration sensor 22 are attached, but a suspension arm or the like can be used instead of the knuckle 13.

  In the embodiment, the rear wheel which is a non-steered wheel has been described. However, when the present invention is applied to a steered wheel such as a front wheel, the wheel steered angle is included in the slip angle β of the wheel W described above. good. The wheel turning angle can be uniquely obtained from the steering angle by detecting the steering angle operated by the driver.

Perspective view of the left wish wheel double wishbone suspension 2 direction view of FIG. Illustration of longitudinal force and lateral force applied to wheels

Explanation of symbols

S suspension device W wheel 13 knuckle (unsprung member)
21 Longitudinal acceleration sensor 22 Lateral acceleration sensor

Claims (2)

A wheel longitudinal force calculating device for calculating a longitudinal force FX parallel to a traveling direction acting on a wheel (W) suspended on a vehicle body via a suspension device (S),
The unsprung member (13) that rotatably supports the wheel (W), the longitudinal acceleration sensor (21) that detects the longitudinal acceleration XG parallel to the rotational surface of the wheel (W), and the rotational surface of the wheel (W) A lateral acceleration sensor (22) for detecting a lateral acceleration YG orthogonal to each other;
Using the coefficient K indicating the longitudinal acceleration XG, the lateral acceleration YG, and the wheel contact load, the longitudinal force FX is
FX = K × (XG × cos β + YG × sin β)
Where β is the slip angle of the wheel and β = tan ⁻¹ (∫YG / ∫XG)
A longitudinal force calculation device for a wheel, characterized by: A wheel lateral force calculation device for calculating a lateral force FY perpendicular to a traveling direction acting on a wheel (W) suspended on a vehicle body via a suspension device (S),
The unsprung member (13) that rotatably supports the wheel (W), the longitudinal acceleration sensor (21) that detects the longitudinal acceleration XG parallel to the rotational surface of the wheel (W), and the rotational surface of the wheel (W) A lateral acceleration sensor (22) for detecting a lateral acceleration YG orthogonal to each other;
The lateral force FY is determined by using the longitudinal acceleration XG, the lateral acceleration YG, and a coefficient K indicating a wheel contact load,
FY = K × (YG × cos β + XG × sin β)
Where β is the slip angle of the wheel and β = tan ⁻¹ (∫YG / ∫XG)
A lateral force calculation device for a wheel, characterized by:

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