JP6458584B2 - Moment analysis device for vehicle, moment analysis method for vehicle, and moment analysis program for vehicle - Google Patents

Description

  The present invention relates to a vehicle moment analysis apparatus, a vehicle moment analysis method, and a vehicle moment analysis program that simulate a tire restoring moment generated around a kingpin axis when the vehicle is stationary.

  In a vehicle such as an automobile, in a so-called stationary state where the steering is steered when the vehicle is stopped, a tire restoring moment is generated around the kingpin axis as a reaction force of the steering. The kingpin shaft is a rotation shaft for giving a steering angle to the tire.

  The restoring moment generated when the vehicle is stationary changes depending on the actual steering angle. The actual rudder angle at the time of stationary is an angle formed by a straight traveling direction when the vehicle is stopped and a direction in which the tire faces by steering.

  Conventionally, the restoring moment has been analyzed using a tire model when the tire is rotating while the vehicle is moving, although it is generated when the vehicle is stationary, that is, when the vehicle is stopped. However, it is difficult to accurately simulate the restoring moment at the time of stationary in the analysis using the tire model when the vehicle moves.

  Non-Patent Document 1 discloses a method for estimating a rack bar axial force generated when a vehicle is stationary. The rack bar axial force is a force applied in the axial direction of the rack bar extending in the vehicle width direction. When the steering shaft rotates by steering, the rotational motion is converted into a linear motion of the rack bar via a pinion or the like. The rack bar axial force is transmitted to, for example, the left and right tie rods, and the tires rotate around the kingpin axis by these tie rods to steer the tires.

  The tire restoring moment can be calculated in consideration of the balance with the rack bar axial force generated when the vehicle is stationary. Therefore, it is considered that the tire restoring moment generated when the vehicle is stationary can be calculated by using the method of Non-Patent Document 1.

441-20102026 Development of rack bar axial force estimation means at the time of slipping (Japan Society for Automotive Engineers Preprint of Scientific Lecture No.92-10)

  However, in the method described in Non-Patent Document 1, in order to obtain the rack bar axial force, it is necessary to calculate the tire contact surface shape that changes every moment when the vehicle is stationary. In this method, the ground contact surface of the tire is calculated by dividing the ground contact surface of the tire into a mesh shape and obtaining the sum of the drag forces of the divided minute regions.

  That is, in Non-Patent Document 1, in order to obtain the rack bar axial force, it is indispensable to analyze the contact area and shape between the tire and the road surface at the time of turning. For this reason, even when trying to calculate the tire restoring moment that occurs when the vehicle is stationary using the method of Non-Patent Document 1, the analysis of the contact area and shape of the tire is complicated, and it is difficult to perform highly reliable simulation. Become.

  In addition, with this method, the restoring moment cannot be directly calculated from the characteristic values indicating the physical characteristics of the tire in the stationary state, that is, values such as the tire contact width, contact length, contact pressure distribution, stiffness value, and friction coefficient. For this reason, the method of Non-Patent Document 1 cannot simulate a restoring moment that reflects the physical characteristics of the tire in a stationary state.

  In view of such a problem, the present invention enables a highly reliable simulation of the restoring moment of the tire generated around the kingpin axis in the stationary state of the vehicle, reflecting the physical characteristics of the tire in the stationary state. An object of the present invention is to provide a vehicle moment analysis apparatus, a vehicle moment analysis method, and a vehicle moment analysis program.

  In order to solve the above problems, a typical configuration of the vehicle moment analyzing apparatus according to the present invention is a restoring moment generated around the kingpin axis as a steering reaction force in a stationary state in which the steering is steered when the vehicle is stopped. In the vehicle moment analysis apparatus that simulates the vehicle, an actual rudder angle measurement unit that measures an actual rudder angle ψ formed by a straight traveling direction of the vehicle and a direction in which the tire faces by steering, and tire characteristic value measurement that measures a tire characteristic value The frictional force based on the frictional characteristics of the tire is larger than the elastic force based on the rigidity characteristic of the tire including the center of the grounding surface among the grounding surfaces of the tire and the actual steering angle ψ and the characteristic value. An area setting unit that sets an area and a sliding area in which the elastic force is greater than the frictional force on the ground contact surface, and an elastic force mode by an elastic force in the adhesion region with reference to the center of the ground contact surface. And a simulation unit that approximates the restoring moment Mz (ψ) with respect to the actual rudder angle ψ using the elastic force moment and the friction force moment. Features.

  Here, in the adhesion region set on the contact surface of the tire, the friction force is larger than the elastic force, so that slip does not occur and the elastic force becomes the restoring force. In the sliding region, since the elastic force is larger than the frictional force, slipping occurs and the frictional force becomes the restoring force. According to the above configuration, the elastic force moment calculated in the adhesion region and the frictional force moment calculated in the slip region are calculated based on the actual steering angle ψ and the tire characteristic value with reference to the center of the tire contact surface. Used to simulate the restoring moment. Therefore, the restoring moment Mz (ψ) reflecting the physical characteristics of the tire in the stationary state can be simulated.

The sliding region set by the region setting unit includes the first portion and the second portion, and the simulation unit calculates the elastic force moment Mz1 (ψ) in the adhesion region, and the friction force in the first portion and the second portion. The moments Mz2 (ψ) and Mz3 (ψ) are calculated, and the restoring moment Mz (ψ) is approximated by the equation (1) including these moments.

  Here, in consideration of the relationship between the elastic force generated on the ground contact surface of the tire and the frictional force in the stationary state, the equation (1) is an elastic force moment Mz1 (ψ) and frictional force moments Mz2 (ψ), Mz3 ( (φ) is a mathematical formula as a tire model. According to the above configuration, the restoring moment Mz (ψ) reflecting the physical characteristics of the tire in the stationary state can be simulated by using the tire characteristic value in the expression (1).

（ただし、値Ｗはタイヤ接地幅、値Ｗｈは接地幅方向における凝着領域と滑り領域との境界、値Ｌはタイヤ接地長、値Ｌｈは接地長方向における凝着領域と滑り領域との境界、値σは接地面内の点（ｘ、ｙ）におけるせん断応力、値μはタイヤの摩擦係数、値ｐｚは接地面内の点（ｘ、ｙ）におけるタイヤ接地圧分布であって、これらの値がタイヤの特性値に含まれる。） The simulation unit may calculate the elastic force moment Mz1 (ψ) by the equation (2), and calculate the friction force moments Mz2 (ψ) and Mz3 (ψ) by the equations (3) and (4).

(However, the value W is the tire contact width, the value Wh is the boundary between the adhesion region and the slip region in the contact width direction, the value L is the tire contact length, and the value Lh is the boundary between the adhesion region and the slip region in the contact length direction. , The value σ is the shear stress at the point (x, y) in the contact surface, the value μ is the coefficient of friction of the tire, and the value pz is the tire contact pressure distribution at the point (x, y) in the contact surface. The value is included in the tire characteristic value.)

  Thereby, by using the tire characteristic values, it is possible to calculate the elastic force moment Mz1 (ψ), the friction force moments Mz2 (ψ), and Mz3 (ψ) with respect to the actual steering angle ψ in the stationary state. Therefore, the restoring moment Mz (ψ) with respect to the actual steering angle ψ can be grasped in relation to the tire characteristic value.

  According to the equation (2), in the adhesion region including the center of the ground plane and set between −Lh and Lh and between −Wh and Wh, the shear stress σ is the distance from the center of the ground plane. The elastic moment Mz1 (ψ) can be calculated by multiplying and multiplying this between -Lh and Lh and between -Wh and Wh. According to Equation (3), in the first part of the slip region set between −Lh and −L / 2 and between −Wh and −W / 2, the tire contact pressure distribution pz Multiplying the distance from the center, multiplying this between -Lh and -L / 2 and between -Wh and -W / 2, and further multiplying by the friction coefficient μ, the frictional force moment Mz2 (ψ) Can be calculated. According to the equation (4), in the second part of the slip region set between Lh and L / 2 and between Wh and W / 2, the tire contact pressure distribution pz is the distance from the center of the contact surface. The frictional force moment Mz3 (ψ) can be calculated by multiplying this by multiple integration between Lh and L / 2 and between Wh and W / 2, and by multiplying by the friction coefficient μ.

（ただし、値Ｋはタイヤのトレッド剛性、値ψslidingは滑りが発生しその後、ψ’（滑り速度）＝０となるまでの実舵角であって、タイヤの特性値に含まれる。） The simulation unit may calculate the shear stress σ (x, y, ψ) with respect to the actual rudder angle ψ at the point (x, y) in the ground plane using the equation (5).

(However, the value K is the tread rigidity of the tire, and the value ψsliding is the actual steering angle until slipping occurs and then ψ ′ (sliding speed) = 0, and is included in the tire characteristic value.)

  Thereby, the shear stress σ (x, y, ψ) with respect to the actual steering angle ψ can be calculated in consideration of the tread rigidity K and the value ψ sliding. According to Equation (5), the tangent of the value ψadhesion (actual rudder angle of the section where elastic deformation occurs at the point of the ground plane) obtained by subtracting ψsliding at the point (x, y) in the ground plane from the actual rudder angle ψ The shear stress σ (x, y, ψ) can be calculated by calculating the value, multiplying this value by the distance from the center of the contact surface to determine the shear deformation amount, and further multiplying this by the tread rigidity K.

  In order to solve the above problems, a representative configuration of the vehicle moment analysis method according to the present invention is a restoring moment generated around the kingpin axis as a steering reaction force in a stationary state in which the steering is steered when the vehicle is stopped. In the vehicle moment analysis method for simulating the vehicle, an actual rudder angle measurement step for measuring the actual rudder angle ψ formed by the straight direction of the vehicle and the direction in which the tire faces by steering, and tire characteristic value measurement for measuring the tire characteristic value Based on the step, the actual steering angle ψ, and the characteristic value, the friction force based on the tire friction characteristic is larger than the elastic force based on the tire rigidity characteristic including the center of the ground contact surface of the tire contact surface. An area setting step for setting an area and a sliding area where the elastic force is greater than the frictional force on the ground contact surface, and the adhesion region is elastic based on the center of the ground contact surface. A simulation step for calculating an elastic force moment due to a force, calculating a frictional force moment due to a frictional force in a sliding region, and approximating a restoring moment Mz (ψ) with respect to an actual steering angle ψ using the elastic force moment and the frictional force moment; It is characterized by including.

  The component corresponding to the technical idea in the vehicle moment analysis apparatus described above and the description thereof are also applied to the vehicle moment analysis method.

  In order to solve the above problems, a typical configuration of the vehicle moment analysis program according to the present invention is a restoring moment generated around the kingpin axis as a steering reaction force in a stationary state in which the steering is steered when the vehicle is stopped. In the vehicle moment analysis program for simulating the vehicle, the actual steering angle measurement processing for measuring the actual steering angle ψ formed by the straight direction of the vehicle and the direction of the tire by steering is measured by the computer, and the characteristic value of the tire is measured. Based on the tire characteristic value measurement processing to be performed, the actual steering angle ψ, and the characteristic value, the friction force based on the tire friction characteristic rather than the elastic force based on the tire rigidity characteristic including the center of the ground contact surface of the tire contact surface is included. Area setting processing for setting a larger adhesion area and a sliding area having a larger elastic force than a frictional force on the ground surface, and the center of the ground surface as a reference Then, the elastic force moment due to the elastic force is calculated in the adhesion region, the frictional force moment due to the frictional force is calculated in the sliding region, and the restoring moment Mz (with respect to the actual steering angle ψ) is calculated using the elastic force moment and the frictional force moment. and a simulation process for approximating (ψ).

  The component corresponding to the technical idea in the vehicle moment analysis apparatus described above and the description thereof are also applied to the vehicle moment analysis program.

  According to the present invention, a tire moment analysis device for a vehicle that can perform a highly reliable simulation of the restoring moment of a tire generated around a kingpin axis in a stationary state of the vehicle, reflecting the physical characteristics of the tire in the stationary state. A vehicle moment analysis method and a vehicle moment analysis program can be provided.

1 is a diagram schematically illustrating a vehicle to which a vehicle moment analysis apparatus according to an embodiment is applied. It is a figure explaining the actual rudder angle at the time of stationary of the vehicle of FIG. It is a block diagram which shows the function of the vehicle moment analyzer in this embodiment. FIG. 4 is a conceptual diagram of a tire model used in the vehicle moment analyzer of FIG. 3. It is a conceptual diagram which shows the example which introduce | transduced the sliding speed to the tire model of FIG. It is a flowchart which shows the process of the vehicle moment analyzer of FIG. It is a figure which compares the simulation result and experimental value by the vehicle moment analyzer of FIG.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

  FIG. 1 is a diagram schematically illustrating a vehicle to which the vehicle moment analysis apparatus according to the present embodiment is applied. The vehicle moment analysis device 100 (see FIG. 3) is a device that simulates a restoring moment Mz (ψ) that occurs in a stationary state in which the steering 104 is steered when the vehicle 102 stops. The restoring moment Mz (ψ) is generated around the kingpin shaft 106 as a steering reaction force of the steering 104 when the vehicle 102 is stationary. The restoring moment Mz (ψ) is also referred to as self-aligning torque (SAT).

  The kingpin shaft 106 serves as a rotation shaft for giving a steering angle (hereinafter referred to as an actual steering angle ψ) to the tire 108 and is, for example, along the axial direction of the strut 110 that supports the suspension. The restoring moment Mz (ψ) occurs around the kingpin axis 106 of the tire 108 that is the right front wheel, but also around the kingpin axis (not shown) of the tire 112 that is the left front wheel. In the figure, the steering mechanism 114 related to the generation of the restoring moment Mz (ψ) of the vehicle 102 is shown as a representative.

  The steering mechanism 114 employs an electric power steering system and includes a motor 118 attached to the steering column 116. The motor 118 provides auxiliary power for the rotation of the steering shaft 120. The steering column 116 includes a torsion bar 122 therein.

  The torsion bar 122 connects the input shaft 124 and the output shaft 126 which are a part of the steering shaft 120, and transmits torque from the input shaft 124 to the output shaft 126 as the steering shaft 120 rotates. The output shaft 126 is connected to one end of the intermediate shaft 130 via the connecting portion 128. The other end of the intermediate shaft 130 is connected to the pinion shaft 134 via the connecting portion 132.

  The torque transmitted to the output shaft 126 is transmitted to the pinion shaft 134 via the connecting portion 128, the intermediate shaft 130 and the connecting portion 132. A pinion is formed on the pinion shaft 134 and meshes with the rack of the rack bar 136. The rack bar 136 is a member extending in the vehicle width direction, and tie rods 138 and 140 are connected to both ends thereof.

  In the steering mechanism 114, the steering shaft 120 is rotated by the steering of the steering 104, and the rotational motion is converted into linear motion of the rack bar 136 via the pinion of the pinion shaft 134. The force accompanying the linear motion of the rack bar 136 is transmitted to the left and right tie rods 138 and 140. In the vehicle 102, for example, the tires 108 and 112 are rotated around the kingpin shaft 106 by the tie rods 138 and 140, and the tires 108 and 112 are steered.

  FIG. 2 is a diagram illustrating the actual steering angle ψ when the vehicle 102 in FIG. 1 is stationary. In the figure, the actual steering angle ψ of the tire 108 is shown with the vehicle 102 viewed from above. As shown in the figure, the actual rudder angle ψ is an angle formed by a straight traveling direction (a direction indicated by a one-dot chain line 142) when the vehicle 102 is stopped and a direction in which the tire 108 faces by steering (a direction indicated by a one-dot chain line 144). .

  FIG. 3 is a block diagram illustrating functions of the vehicle moment analysis apparatus 100 according to the present embodiment. The vehicle moment analysis device 100 is a device that simulates a restoring moment Mz (ψ) that occurs when the vehicle 102 is stationary, and includes, for example, an input unit 150, a simulation unit 152, a tire model storage unit 154, A display unit 156. The vehicle moment analysis device 100 is an independent device different from the vehicle 102 in the present embodiment, but the installation location is arbitrary and may be arranged in the vehicle 102.

  The input unit 150 includes an actual rudder angle measurement unit 158, a tire characteristic value measurement unit 160, and a region setting unit 162. The actual rudder angle measurement unit 158 measures the actual rudder angle ψ of the tire 108 as shown in FIG. 2 when the vehicle 102 is stationary. The tire characteristic value measuring unit 160 measures a characteristic value (described later) indicating the physical characteristics of the tire 108. The region setting unit 162 sets an adhesion region 172 and a slip region 174 on the ground contact surface 170 of the tire 108 shown in FIG. 4 based on the actual steering angle ψ and the characteristic value (described later).

  The simulation unit 152 is configured by a computer that operates according to the vehicle moment analysis program in the present embodiment. The simulation unit 152 performs calculation by substituting the actual steering angle ψ and the tire characteristic value measured by the input unit 150 into the equations (1) to (5) as the tire model stored in the tire model storage unit 154. , The restoring moment Mz (ψ) with respect to the actual steering angle ψ is approximated. The display unit 156 displays the restoring moment Mz (ψ) approximated by the simulation unit 152 as a simulation result.

  FIG. 4 is a conceptual diagram of a tire model used in the vehicle moment analysis apparatus 100 of FIG. First, the tire model of the present embodiment is based on the concept of a so-called brush model. In the brush model, the tire contact surface is assumed to be a collection of elastic bodies (brush), the brush gradually deforms from the stepping side, and the elastic force accompanying the deformation of the brush is the tire that contacts the contact surface (vertical pressure) with the contact surface. When the frictional force multiplied by the friction coefficient μ is exceeded, the tire slips.

  In the tire model of the present embodiment, the adhesion region 172 set by the region setting unit 162 in the ground contact surface 170 shown in FIG. 4 is a region where the frictional force is larger than the elastic force at the time of stationary, and slipping occurs. It does not occur and the elastic force becomes the restoring force. In addition, the set slip region 174 in the ground contact surface 170 is a region where the elastic force is larger than the friction force at the time of stationary, and slip occurs, and the friction force becomes a restoring force.

  The values W and L in the figure indicate the tire contact width and tire contact length of the contact surface 170, respectively. In the figure, the X axis is set along the contact length direction, the Y axis is set along the contact width direction, and the position of the point in the contact surface 170 is (x, y). Adhesion region 172 includes center O of ground plane 170 and is set between -Lh and Lh and between -Wh and Wh. The sliding region 174 includes a first portion 176 and a second portion 178. The first portion 176 is set between -Lh and -L / 2 and between -Wh and -W / 2. The second part is set between Lh and L / 2 and between Wh and W / 2. That is, the value Wh and the value Lh are the boundary between the adhesion region 172 and the sliding region 174 in the contact width direction and the contact length direction, respectively, and the magnitude relationship between the elastic force and the friction force changes with this boundary. .

  The simulation unit 152 calculates, based on the center O of the contact surface 170, an elastic force moment based on the tire stiffness characteristic in the adhesion region 172, and calculates a friction force moment based on the tire friction property in the slip region 174. Then, the simulation unit 152 approximates the restoring moment Mz (ψ) with respect to the actual steering angle ψ using these elastic force moment and friction force moment.

Hereinafter, the calculation by the simulation unit 152 will be specifically described. In consideration of the relationship between the elastic force generated on the ground contact surface of the tire and the frictional force in the stationary state, the equation (1) is an elastic force moment Mz1 (ψ), frictional force moments Mz2 (ψ), and Mz3 (ψ). Is a mathematical formula as a tire model combining

The elastic force moment Mz1 (ψ) is calculated from the equation (2).

  According to Equation (2), in the adhesion region 172 including the center O of the ground plane 170 and set between −Lh and Lh and between −Wh and Wh, the shear stress σ (x, y, ψ) is multiplied by the distance from the center O of the ground plane 170 to the point (x, y), and this is multiply integrated between −Lh and Lh and between −Wh and Wh, whereby the elastic force moment Mz1 (Ψ) can be calculated.

Friction force moments Mz2 (ψ) and Mz3 (ψ) are calculated from equations (3) and (4), respectively.

  Here, the value μ is the coefficient of friction of the tire. The tire contact pressure distribution pz is a distribution of contact pressure over the entire contact surface. For example, air pressure, tire load, tire posture, lateral slip that generates cornering force, and before and after generating driving force and braking force. Depending on the degree of direction slip, it varies with the shape of the ground plane. The tire contact pressure distribution pz also affects the driving force, braking force, cornering force, restoring moment Mz (ψ) required for vehicle motion, and tire wear performance.

  According to the equation (3), in the first portion 176 of the slip region 174 set between −Lh and −L / 2 and between −Wh and −W / 2, the tire contact pressure distribution pz (x , Y) is multiplied by the distance from the center O of the ground plane 170 to the point (x, y), and this is multiply integrated between -Lh and -L / 2 and between -Wh and -W / 2. Further, the frictional force moment Mz2 (ψ) can be calculated by multiplying by the friction coefficient μ.

  According to the equation (4), in the second portion 178 of the slip region 174 set between Lh and L / 2 and between Wh and W / 2, the tire contact pressure distribution pz (x, y) Multiply the distance from the center O of the ground plane 170 to the point (x, y), multiply this between Lh and L / 2 and between Wh and W / 2, and further multiply by the friction coefficient μ. Can calculate the frictional force moment Mz3 (ψ).

  Here, each value included in the above equations (2), (3), and (4) is one of the characteristic values of the tire. Therefore, the simulation unit 152 can calculate the elastic force moment Mz1 (ψ) and the friction force moments Mz2 (ψ) and Mz3 (ψ) with respect to the actual steering angle ψ in the stationary state by using the tire characteristic values. By using the equation (1), the restoring moment Mz (ψ) with respect to the actual steering angle ψ can be grasped in relation to the tire characteristic value.

Further, the shear stress σ (x, y, ψ) is calculated from the equation (5).

  Here, the value K is the tread rigidity of the tire, and the value ψsliding is the actual steering angle until ψ ′ (sliding speed) = 0 after slipping, and is included in the tire characteristic value. That is, Expression (5) is an expression in which a slip speed is introduced into the tire model, and the shear stress σ (x, y, ψ) with respect to the actual steering angle ψ is calculated in consideration of the value ψ sliding.

  FIG. 5 is a conceptual diagram showing an example in which a slip speed is introduced into the tire model of FIG. FIG. 5A is a conceptual diagram of adhesion-slip characteristics at a point on the ground contact surface 170 at the time of stationary, for example, the tread block α shown in FIG. FIG. 5B is a diagram showing the relationship between the actual steering angle ψ, the value ψadhesion, and the value ψsliding in the tread block α.

  As shown in FIG. 4, the tread block α is located in the sliding region 174 and elastically deforms without slipping when the shear stress does not exceed the ground pressure. Further, the actual steering angle ψ increases and the shear stress is grounded. If the pressure is exceeded, slippage occurs without elastic deformation. Specifically, when the tread block α shifts from the state A to the state B as shown on the left side of FIG. 5A, the actual rudder angle ψ increases, shear stress is generated, and the restoring moment increases. Elastically deforms as shown on the right side of FIG.

  Furthermore, as shown in the left side of FIG. 5 (a), when the tread block α shifts from the state B to the state C, the actual steering angle ψ increases, but the restoring moment does not change and slipping occurs. I understand that. Therefore, the tread block α maintains its shape without being elastically deformed when the state B shifts to the state C as shown on the right side of FIG. Further, of the actual rudder angle ψ, the actual rudder angle in a section where the tread block α does not slip and elastic deformation occurs (from state A to state B) is defined as a value ψadhesion. Therefore, here, the actual steering angle in the state B is ψadhesion.

  Subsequently, when shifting from the state C to the state D, the actual steering angle ψ does not increase but starts to decrease. This indicates that the slipping speed (differential value of ≈ψ) has changed from “positive” to “negative” through the sliding speed “0”, that is, through a stationary state. For this reason, ψsliding is the actual steering angle from state B where the slip occurs to state C where the slip speed is “0”. At this time, as shown in FIG. 5B, the actual rudder angle ψ is the sum of ψadhesion and ψsliding and becomes ψadhesion (= ψ-ψsliding). However, since ψsliding differs depending on the tread block, that is, the point of the ground contact surface 170, in Equation (5), ψsliding is generalized as ψsliding (x, y). Note that sliding = 0 at points in the adhesion region 172 such as near the center O of the ground contact surface 170, while sliding occurs at points sliding 174 even if the actual rudder angle ψ is small. ≒ ψ.

  When the tread block α shifts from the state C to the state D as shown on the left side of FIG. 5A, the actual steering angle ψ decreases “positive”. A shear stress opposite to the generated shear stress (negative) is generated. For this reason, as shown on the right side of FIG. 5A, the tread block α returns to the same shape as that of the state A when the state changes from the state C to the state D and is elastically deformed.

  On the other hand, since the actual rudder angle ψ is “positive” at the point of the adhesion region 172 such as the vicinity of the center O of the ground contact surface 170, positive shear stress is generated. That is, in the transition from the state C to the state D where the increase / decrease of the actual steering angle ψ is reversed, a negative shear stress is generated at the point of the slip region 174 and a positive shear stress is generated at the point of the adhesion region 172. Therefore, the history of shear stress differs between when the actual rudder angle ψ increases and when it decreases, and as a result, hysteresis occurs in the restoring moment as shown on the left side of FIG.

  In the transition from the state D to the state E, as shown in the left side of FIG. 5A, the actual steering angle ψ further decreases, negative shear stress is generated, and the restoring moment also shifts to negative. As shown on the right side of FIG. 5A, the tread block α in the state E has a shape that is elastically deformed in the opposite direction compared to the state B, for example. Subsequently, when shifting from the state E to the state F, the actual rudder angle ψ is decreased, a negative restoring moment is maintained, and slipping occurs. Therefore, the tread block α maintains its shape without being elastically deformed when shifting from the state E to the state F as shown on the right side of FIG. In the state F, the actual rudder angle ψ has started increasing from decreasing. Therefore, ψsliding is the actual rudder angle from the state E where the slip occurs to the state F where the slip speed becomes “0”.

  Thus, according to the equation (5) in which the slip speed is introduced into the tire model, the tangent value of ψadhesion (= ψ−ψsliding (x, y)) at the point (x, y) in the contact surface is obtained. Is multiplied by the distance from the center O of the ground contact surface 170 to the point (x, y) to obtain the shear deformation amount, and further multiplied by the tread rigidity K, whereby the shear stress σ (x, y, ψ) can be calculated. .

  In the present embodiment, the elastic force moment calculated in the adhesion region 172 as shown in Expression (1) based on the actual steering angle ψ and the above-described characteristic value of the tire with reference to the center O of the ground contact surface 170 of the tire 108. The restoring moment is simulated using Mz1 (ψ) and the frictional force moments Mz2 (ψ) and Mz3 (ψ) calculated in the sliding region 174. Therefore, according to the tire model shown in Formula (1), the restoring moment Mz (ψ) reflecting the physical characteristics of the tire in the stationary state can be simulated.

  Further, when calculating the shear stress σ (x, y, ψ), the restoring moment Mz with respect to the actual steering angle ψ as shown in FIG. 5A is obtained by using the equation (5) in which the slip speed is introduced into the tire model. The hysteresis of (ψ) can also be shown.

  FIG. 6 is a flowchart showing processing of the vehicle moment analysis apparatus 100 of FIG. First, the actual steering angle measurement unit 158 and the tire characteristic value measurement unit 160 of the input unit 150 measure the actual steering angle ψ and tire characteristic value of the tire when the vehicle 102 is stationary (step S100).

  Next, the region setting unit 162 of the input unit 150 sets the adhesion region 172 and the slip region 174 with respect to the tire contact surface 170 based on the actual steering angle ψ and the tire characteristic value (step S102).

  Subsequently, the simulation unit 152 reads the tire model including the above formulas (1) to (5) from the tire model storage unit 154, and substitutes the actual steering angle ψ and the tire characteristic value into the tire model. The simulation unit 152 calculates the elastic force moment Mz1 (ψ) in the adhesion region 172 using the center O of the ground contact surface 170 as a reference, and the friction force moments Mz2 (ψ) and Mz3 (ψ) in the sliding region 174. calculate. Further, the simulation unit 152 uses these moments Mz1 (ψ), Mz2 (ψ), and Mz3 (ψ) to generate a highly reliable restoring moment Mz (ψ) that reflects the physical characteristics of the tire in the stationary state. Approximate (step S104).

  Next, the simulation part 152 performs the process of step S100 again, when continuing simulation (step S106, Yes). On the other hand, when the simulation is not continued in step S106 (No), the simulation unit 152 outputs the approximated restoration moment Mz (ψ) to the display unit 156 as a simulation result. The display unit 156 may appropriately display the approximated restoration moment Mz (ψ) as a graph.

  FIG. 7 is a diagram comparing a simulation result obtained by the vehicle moment analysis apparatus 100 of FIG. 3 with an experimental value. In the figure, the horizontal axis represents the actual steering angle ψ, and the vertical axis represents the restoring moment Mz. Here, the simulation results indicated by the solid line and the alternate long and short dash line in FIG. 7A are obtained with the vertical load Fz being 6000N and 3000N, respectively, and the experimental values are indicated by dotted lines. The simulation can be executed by simulation software such as CarSim (registered trademark) or ADAMS (registered trademark).

  As shown in FIG. 7A, the simulation results and the experimental values almost coincide with each other. That is, it is clear that the vehicle moment analysis apparatus 100 can perform a highly reliable simulation of the restoring moment Mz (ψ).

  FIG. 7B shows, as a comparative example, a case where the restoring moment Mz (ψ) is simulated using a tire model when the tire rotates while the vehicle is moving. The simulation result of the comparative example indicated by a solid line in FIG. 7B is obtained with a vertical load Fz of 6000 N, and the experimental value is indicated by a dotted line.

  The simulation result and the experimental value according to the comparative example have different shapes as shown in FIG. That is, in the analysis using the tire model at the time of movement of the vehicle as in the comparative example, it is difficult to accurately simulate the restoring moment Mz (ψ) that is generated when the vehicle is stationary, that is, when the vehicle is stopped. I understand that.

  On the other hand, in the vehicle moment analyzing apparatus 100, the tire physical characteristics regarding the restoring moment Mz (ψ) are obtained by a tire model including the above formulas (1) to (5) based on the actual steering angle ψ and the tire characteristic values. This makes it possible to simulate with high reliability reflecting the above.

  For this reason, in the present embodiment, it is possible to grasp the relationship between the change in the physical characteristics of the tire and the influence on the restoring moment Mz in the stationary state. As an example, the influence on the restoring moment Mz can be grasped by changing the contact width W and the contact length L, the contact pressure distribution pz, the tire tread rigidity K, and the like as the characteristic values of the tire.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  The present invention can be used for a vehicle moment analysis device, a vehicle moment analysis method, and a vehicle moment analysis program for simulating a tire restoring moment generated around a kingpin axis when the vehicle is stationary.

DESCRIPTION OF SYMBOLS 100 ... Vehicle moment analyzer, 102 ... Vehicle, 104 ... Steering, 106 ... Kingpin shaft, 108, 112 ... Tire, 110 ... Strut, 114 ... Steering mechanism, 116 ... Steering column, 118 ... Motor, 120 ... Steering shaft, 122 ... Torsion bar, 124 ... Input shaft, 126 ... Output shaft, 128, 132 ... Connecting portion, 130 ... Intermediate shaft, 134 ... Pinion shaft, 136 ... Rack bar, 138, 140 ... Tie rod, 150 ... Input portion, 152 ... Simulation unit, 154 ... tire model storage unit, 156 ... display unit, 158 ... actual steering angle measurement unit, 160 ... tire characteristic value measurement unit, 162 ... region setting unit, 170 ... ground contact surface, 172 ... adhesion region, 174 ... Sliding region, 176 ... first part, 178 ... second part

Claims (6)

In a vehicle moment analyzer that simulates a restoring moment generated around a kingpin axis as a reaction force of the steering in a stationary state in which the steering is steered when the vehicle is stopped,
And the actual steering angle measurement unit that measures the actual steering angle ψ formed between the direction facing the tire by the steering and straight running direction of the vehicle,
A tire characteristic value measuring unit for measuring the characteristic value of the tire;
Based on the actual steering angle ψ and the characteristic value, the friction force based on the friction characteristic of the tire is more than the elastic force based on the rigidity characteristic of the tire including the center of the ground contact surface of the tire contact surface. A region setting unit for setting a large adhesion region and a sliding region in which the elastic force is larger than the frictional force in the ground contact surface;
Based on the center of the ground contact surface, an elastic force moment due to the elastic force is calculated in the adhesion region, a friction force moment due to the friction force is calculated in the slip region, and the elastic force moment and the friction force moment are calculated. used, vehicle moment analysis apparatus characterized by comprising a simulation unit for approximating the actual steering angle restore moment Mz against the ψ (ψ). The sliding region set by the region setting unit includes a first portion and a second portion,
The simulation unit
Elastic force moment Mz1 (ψ) is calculated in the adhesion region, and friction force moments Mz2 (ψ) and Mz3 (ψ) are calculated in the first part and the second part, respectively, and equations (1) including these moments are calculated. The vehicle moment analysis apparatus according to claim 1, wherein the restoring moment Mz (ψ) is approximated by:

The simulation unit
The elastic force moment Mz1 (ψ) is calculated by equation (2),
3. The vehicle moment analysis apparatus according to claim 2, wherein the frictional force moments Mz2 (ψ) and Mz3 (ψ) are calculated by Equations (3) and (4).

(However, the value W is the tire contact width, the value Wh is the boundary between the adhesion region and the slip region in the contact width direction, the value L is the tire contact length, and the value Lh is the boundary between the adhesion region and the slip region in the contact length direction. , The value σ is the shear stress at the point (x, y) in the contact surface, the value μ is the coefficient of friction of the tire, and the value pz is the tire contact pressure distribution at the point (x, y) in the contact surface. The value is included in the tire characteristic value.) The simulation unit calculates a shear stress σ (x, y, ψ) with respect to the actual rudder angle ψ at a point (x, y) in the ground contact surface according to Equation (5). The vehicle moment analysis apparatus described.

(However, the value K is the tread rigidity of the tire, and the value ψsliding is the actual steering angle until ψ ′ (sliding speed) = 0 after slipping, and is included in the tire characteristic value.) In a vehicle moment analysis method for simulating a restoring moment generated around a kingpin axis as a reaction force of the steering in a stationary state where the steering is steered when the vehicle is stopped,
And the actual steering angle measuring step of measuring the actual steering angle ψ formed between the direction facing the tire by the steering and straight running direction of the vehicle,
A tire characteristic value measuring step for measuring the characteristic value of the tire;
Based on the actual steering angle ψ and the characteristic value, the friction force based on the friction characteristic of the tire is more than the elastic force based on the rigidity characteristic of the tire including the center of the ground contact surface of the tire contact surface. A region setting step for setting a large adhesion region and a sliding region in which the elastic force is larger than the frictional force in the ground contact surface;
Based on the center of the ground contact surface, an elastic force moment due to the elastic force is calculated in the adhesion region, a friction force moment due to the friction force is calculated in the slip region, and the elastic force moment and the friction force moment are calculated. used, vehicle moment analysis method, which comprises a simulation step of approximating the actual steering angle restore moment Mz against the ψ (ψ). In a vehicle moment analysis program for simulating a restoring moment generated around a kingpin axis as a reaction force of the steering in a stationary state where the steering is steered when the vehicle is stopped,
And the actual steering angle measuring process of measuring the actual steering angle ψ formed between the direction facing the tire by the steering and straight running direction of the vehicle,
Tire characteristic value measurement processing for measuring the characteristic value of the tire;
Based on the actual steering angle ψ and the characteristic value, the friction force based on the friction characteristic of the tire is more than the elastic force based on the rigidity characteristic of the tire including the center of the ground contact surface of the tire contact surface. A region setting process for setting a large adhesion region and a sliding region in which the elastic force is larger than the frictional force in the ground contact surface;
Based on the center of the ground contact surface, an elastic force moment due to the elastic force is calculated in the adhesion region, a friction force moment due to the friction force is calculated in the slip region, and the elastic force moment and the friction force moment are calculated. used, the vehicle moment analysis program, characterized in that to execute a simulation processing for approximating the restore moment Mz against the actual steering angle [psi ([psi).

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