Evaluation method for tuck-in characteristic of vehicle

Abstract

To enable simple and accurate evaluation of tuck-in characteristics of a vehicle.SOLUTION: Provided is an evaluation method for tuck-in characteristics of a vehicle, including a second step S2 of making the vehicle travel to measure a state of the vehicle during traveling. The second step S2 includes: a steady circular turning step S21; a deceleration step S22 of inducing tuck-in in the vehicle from the steady circular turning state; a measurement step S23 of measuring a yaw rate from the steady circular turning step S21 to the deceleration step S22; and an evaluation step S24 of evaluating the tuck-in characteristics of the vehicle on the basis of the yaw rate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for evaluating the tuck-in characteristics of a vehicle. [Background technology]

[0002] The following Patent Document 1 describes a tire evaluation method that includes steps of accelerating a vehicle from a first point to a second point, measuring a steering angle α1 at the first point and a steering angle α2 at the second point, and evaluating steering characteristics based on the difference between the steering angles (α2-α1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-172731 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a strong demand for vehicles to avoid tuck-in, which is when a vehicle turns to the inside of a turn. Therefore, a method is needed that can easily and accurately evaluate the tuck-in characteristics of a vehicle.

[0005] The present invention has been devised in view of the above problems, and has as its main object to provide a vehicle evaluation method that can easily and accurately evaluate the tuck-in characteristics of a vehicle. [Means for solving the problem]

[0006] The present invention is a method for evaluating the tuck-in characteristics of a vehicle, comprising: a first step of preparing a vehicle equipped with tires; and a second step of running the vehicle and measuring the state of the vehicle while running, the second step comprising: a steady circular turning step of keeping the steering angle of the vehicle constant and running the vehicle in a steady circular turn at a constant speed; a deceleration step of applying longitudinal deceleration to the vehicle from the steady circular turning state while maintaining the steering angle to induce tuck-in of the vehicle; a step of measuring at least a yaw rate of the vehicle from the steady circular turning step to the deceleration step; and an evaluation step of evaluating the tuck-in characteristics of the vehicle based on the yaw rate. [Effects of the Invention]

[0007] By employing the above-described configuration, the tire evaluation method of the present invention can easily and accurately evaluate the tuck-in characteristics of a vehicle. [Brief explanation of the drawings]

[0008] [Figure 1] 4(a) is a flowchart showing the tire evaluation method of the present invention, and FIG. 4(b) is a flowchart showing the second step. [Figure 2] 1 is a schematic diagram showing an example of a vehicle used in an evaluation method of the present invention. [Figure 3] FIG. 10 is a schematic diagram for explaining a steady circular turning step. [Figure 4] FIG. 2 is a schematic diagram showing the travel trajectories of a vehicle equipped with tire A and a vehicle equipped with tire B. [Figure 5] 1 is a graph showing time-series measurement results of the yaw rate and speed of a vehicle equipped with tire A. [Figure 6] 10 is a graph showing time-series measurement results of the yaw rate and speed of a vehicle equipped with tire B. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, one embodiment of the present invention will be described with reference to the drawings. The drawings include exaggerated representations and representations that differ from the dimensional ratios of the actual structure to facilitate understanding of the present invention. Furthermore, when there are multiple embodiments, the same or common elements are designated by the same reference numerals throughout the specification, and redundant explanations will be omitted.

[0010] 1(A) is a flowchart showing a method for evaluating the tuck-in characteristics of a vehicle of the present invention (hereinafter, sometimes simply referred to as the "evaluation method"). In this specification, "good tuck-in characteristics" refers to the performance of a vehicle that does not turn too far to the inside of a turn during cornering, and "poor tuck-in characteristics" refers to the performance of a vehicle that turns too far to the inside of a turn during cornering. In other words, a vehicle with good tuck-in characteristics is a vehicle that can make stable cornering, and a vehicle with poor tuck-in characteristics is a vehicle that is prone to unstable cornering.

[0011] As shown in FIG. 1(A), the evaluation method of this embodiment includes a first step S1 and a second step S2.

[0012] In a first step S1, a vehicle 1 (shown in FIG. 3) equipped with a tire 2 is prepared. For example, a passenger car is preferably used as the vehicle 1. The passenger car may be of various drive systems, such as front-wheel drive, rear-wheel drive, or four-wheel drive, with front-wheel drive being particularly preferred. The vehicle 1 is not limited to a passenger car, but may also be a truck or a bus. The vehicle may be either engine-driven or motor-driven (electric vehicle). Steering of the vehicle 1 is not limited to being done by a person, but may be done by various devices (not shown), such as an automatic driving device. The vehicle 1 is preferably an automatic vehicle, but may also be a manual transmission vehicle. The tire 2 may be any tire suitable for the vehicle 1, and for example, a pneumatic tire or a non-pneumatic tire that is not filled with air may be used.

[0013] Fig. 2 is a schematic diagram showing an example of a vehicle 1 according to this embodiment. As shown in Fig. 2, the vehicle 1 is provided with, for example, a steering wheel 3 for steering the vehicle 1 and a yaw rate sensor 4 for measuring the yaw rate Y of the vehicle 1. In this specification, the rotation angle of the steering wheel 3 is taken as the steering angle of the vehicle 1 (hereinafter, sometimes simply referred to as "steering angle θ").

[0014] The vehicle 1 may also be provided with, for example, a steering sensor 5 for measuring the steering angle θ, a speed sensor 6 for measuring the speed V of the vehicle 1, and an acceleration sensor 7 for measuring the lateral acceleration or longitudinal acceleration of the vehicle 1. For example, a V-BOX manufactured by Racelogic (UK) or an inertial measurement unit (IMU sensor) is preferably used as the yaw rate sensor 4, the speed sensor 6, and the acceleration sensor 7. In this specification, the lateral direction refers to a direction perpendicular to the traveling direction of the vehicle 1 (the tangent direction of a circle) when the vehicle 1 is turning. When the vehicle 1 is turning, the lateral acceleration is defined as an acceleration perpendicular to the traveling direction of the vehicle 1 and toward the outside of the turn. In this specification, the longitudinal direction refers to a direction parallel to the traveling direction of the vehicle. When the longitudinal acceleration is defined as an acceleration toward the traveling direction of the vehicle, it is defined as a positive acceleration.

[0015] Furthermore, in the case of a vehicle 1 having an engine, the vehicle 1 may be provided with a throttle opening sensor 8 for measuring the opening of a throttle valve (accelerator opening K (not shown)). Furthermore, the vehicle 1 of this embodiment is provided with control means 9 connected to each of the sensors 4 to 8. The control means 9 has a function of, for example, controlling the operation of each of the sensors 4 to 8, and recording or outputting each piece of data transmitted in time series from each of the sensors 4 to 8 at each unit time.

[0016] In the evaluation method of this embodiment, a first step S1 is followed by a second step S2. In the second step S2, the vehicle 1 is driven and the state of the vehicle 1 while it is driving is measured. FIG. 1(B) is a flowchart showing the second step S2. As shown in FIG. 1(B), the second step S2 includes a steady circular turning step S21, a deceleration step S22, a measurement step S23, and an evaluation step S24.

[0017] In the second step S2, first, the vehicle 1 is driven, and a steady circular turning step S21 is performed. FIG. 3 is a schematic diagram for explaining the steady circular turning step S21. As shown in FIG. 3, in the steady circular turning step S21, the steering angle θ of the vehicle 1 is kept constant, and the vehicle 1 makes a steady circular turn at a constant speed V. In the steady circular turning step S21, for example, the steering wheel 3 is steered (rotated) in one direction, either left or right (left in the figure), and the vehicle 1 makes a turn in the same direction. In this specification, a "steady circular turn" refers to turning at a substantially constant speed V and a constant turning radius r. In addition, in this specification, the term "substantially" means that the speed V and turning radius r are constant within a range that can solve the problem of the present invention, and includes a range that is not constant in the strict sense.

[0018] It is desirable that the lateral acceleration αt of the vehicle 1 during steady circular turning be equal to or less than the limit lateral acceleration of the tire 2. In this specification, the "limit of the tire 2" refers to the traveling state at a speed just before the vehicle 1 starts to skid during turning. In other words, steady circular turning is possible when the lateral acceleration αt is equal to or less than the limit lateral acceleration of the tire 2. Conversely, when the lateral acceleration αt exceeds the limit lateral acceleration of the tire 2, steady circular turning becomes impossible. Furthermore, when the lateral acceleration αt exceeds the limit lateral acceleration of the tire 2, the change in the yaw rate Y tends to be large.

[0019] If the lateral acceleration αt of the vehicle 1 is excessively small, it may be difficult to induce the vehicle 1 to tuck in in the next deceleration step S22. In order to make it easier to induce the vehicle 1 to tuck in, the lateral acceleration αt of the vehicle 1 during steady circular turning should be set to 8 to 11 m / s. 2 From the same viewpoint, the turning radius r of the vehicle 1 during steady circular turning is preferably in the range of 60 to 120 m, for example.

[0020] In the steady circular turning step S21, for example, it is desirable that the vehicle make a circular turn of at least one revolution (360°), and more desirably at least 1.5 revolutions. This makes it possible to reduce (stabilize) the change in the yaw rate Y over time in the steady circular turning step S21. Although not particularly limited, it is desirable that the vehicle speed V be 70 to 120 km / h in the steady circular turning step S21, for example.

[0021] The road surface R on which the vehicle 1 makes a steady circular turn is not particularly limited as long as it is a road surface on which the vehicle 1 can run, but is preferably, for example, a dry asphalt road surface.

[0022] Next, deceleration step S22 is performed. In deceleration step S22, from the steady circular turning state, longitudinal deceleration is applied to the vehicle 1 while maintaining the steering angle θ, thereby inducing a tuck-in of the vehicle 1. A vehicle with good tuck-in characteristics will not undergo significant tuck-in even when deceleration is applied. On the other hand, a vehicle with poor tuck-in characteristics will undergo significant tuck-in when deceleration is applied. In this specification, deceleration means negative longitudinal acceleration. When deceleration is applied to the vehicle 1, the speed V continuously decreases without increasing.

[0023] Deceleration is 1.96 m / s 2It is desirable that the deceleration is 0.8 m / s or less. Alternatively, it is desirable that the deceleration step S22 is performed by releasing the accelerator of the vehicle 1. This causes a relatively large load to act on the front wheels of the vehicle 1, reducing the frictional force of the rear wheels, making tuck-in more likely to occur. If the deceleration is excessively small, even in a vehicle with poor tuck-in characteristics, tuck-in will not be induced, and the accuracy of the tuck-in characteristics may deteriorate. For this reason, the deceleration is 0.8 m / s or less. 2 More than 1.0m / s is desirable. 2 The above is even more desirable. The throttle valve opening is 0 (zero), and the throttle valve opening is 0.9 to 1.5 m / s 2 It is desirable to set the shift position so that the deceleration is

[0024] The measurement step S23 is performed from the steady circular turning step S21 to the deceleration step S22. In the measurement step S23, at least the yaw rate Y of the vehicle 1 is measured from the steady circular turning step S21 to the deceleration step S22. In the measurement step S23 of this embodiment, the yaw rate Y is measured chronologically for each unit time by the yaw rate sensor 4.

[0025] In addition, in the measurement step S23, at least one of the steering angle θ of the vehicle 1, the speed V of the vehicle 1, the longitudinal acceleration αs of the vehicle 1, the lateral acceleration αt of the vehicle 1, or the accelerator opening K of the vehicle T may be measured. The steering angle θ of the vehicle 1 is measured by a steering sensor 5. The speed V is measured by a speed sensor 6. The longitudinal acceleration αs and the lateral acceleration αt are measured by an acceleration sensor 7. The accelerator opening K is measured by a throttle opening sensor 8. Each parameter (θ, V, αs, αt, K) is measured, for example, in time series at each unit time by each sensor.

[0026] After the measurement step S23, an evaluation step S24 is performed. In the evaluation step S24 of this embodiment, the tuck-in characteristic of the vehicle 1 is evaluated based on at least the yaw rate Y. In the evaluation step S24, for example, the tuck-in characteristic is evaluated based on the yaw rate Y measured in time series for each unit time from the steady circular turning step S21 to the deceleration step S22.

[0027] Furthermore, by measuring the speed V in measurement step S23, it is possible to evaluate the time from when the accelerator is released until the vehicle 1 comes to a stop. By measuring the steering angle θ, it is possible to evaluate the change in yaw rate due to steering. Furthermore, by measuring the steering angle θ, it is possible to check whether a change in yaw rate is occurring due to steering by a person. By measuring the longitudinal acceleration αs and the lateral acceleration αt, it is possible to evaluate the change in the load acting on the vehicle 1 and the direction of the load. By measuring the accelerator opening degree K, it is possible to evaluate the variation in the person's operation relative to the longitudinal acceleration. Furthermore, by measuring the accelerator opening degree K, it is possible to check the variation at the start of the deceleration step due to a person.

[0028] In the evaluation method of this embodiment, the tire 2 mounted on the vehicle 1 is replaced and tested on the same vehicle 1, whereby the tuck-in characteristics of the tire 2 can be evaluated.

[0029] Although a particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment and can be modified and practiced in various ways. [Example]

[0030] A test was conducted to induce tuck-in in the vehicle 1 using the evaluation method of the present invention. The common specifications and test method are as follows.

[0031] <Common specifications> Tire size: 235 / 45R19 Rim size: 7.5J Vehicle: Passenger electric vehicle Turning radius: 80m Speed V:93km / h Deceleration step: Accelerator off

[0032] <Tuck-in characteristics> Two types of tires, A and B, were prepared, each of the same size but with different specifications. Tire A was mounted on the vehicle and a test was conducted, and then tire A was replaced with tire B and another test was conducted on the same vehicle. Tire A and tire B were mounted on all wheels of the vehicle. In addition, the yaw rate Y and velocity V of the vehicle were measured time-series for each unit time during the steady-state turning step and the deceleration step. In the steady-state turning step, the vehicle made two turns.

[0033] The test results are shown in Figs. 4 to 6. Fig. 4 is a schematic diagram showing the travel trajectories of a vehicle fitted with tire A (hereinafter referred to as vehicle A) and a vehicle fitted with tire B (hereinafter referred to as vehicle B). As mentioned above, vehicle A and vehicle B are the same vehicle. Fig. 5 is a graph showing the yaw rate and speed of vehicle A over time. Fig. 6 is a graph showing the yaw rate and speed of vehicle B over time. In Figs. 5 and 6, the horizontal axis shows elapsed time, and the vertical axis shows yaw rate Y and speed V.

[0034] From FIG. 4, it can be seen that vehicle A has better tuck-in characteristics than vehicle B. On the other hand, referring to FIGS. 5 and 6, it can be seen that for both vehicle A and vehicle B, the amount of change in yaw rate Y is small before the accelerator is released, and the change in yaw rate Y becomes larger after the accelerator is released. As a result, the graphs of FIGS. 5 and 6 make it possible to easily and accurately determine the accelerator-released state. It can also be seen that vehicle B has a larger increase in yaw rate Y after the accelerator is released than vehicle A. This can be understood to be because, when the vehicle tucks in, the rear wheels slip significantly, resulting in a larger change in yaw rate Y. For this reason, it can be seen that a vehicle such as that shown in the graph of FIG. 6 has worse tuck-in characteristics than a vehicle such as that shown in the graph of FIG. 5. Therefore, it can be seen that the evaluation method of the present invention, which can obtain a graph such as that shown in FIG. 5 or 6, can easily and accurately evaluate the tuck-in characteristics of a vehicle (tire).

[0035] Furthermore, as shown in Figures 5 and 6, after the accelerator is released, the vehicle speed V continuously decreases. However, it can be seen that the decrease in speed of vehicle A, which has good tuck-in characteristics, is smaller than the decrease in speed of vehicle B, which has poor tuck-in characteristics, so it can be understood that vehicle speed can also be an index for evaluating tuck-in characteristics. In this way, it can be said that tuck-in characteristics can be evaluated more accurately by measuring the vehicle speed V during the steady circular turning step and the deceleration step.

[0036] [Note] The present invention includes the following aspects.

[0037] [Invention 1] A method for evaluating tuck-in characteristics of a vehicle, comprising: The first step is to prepare a vehicle with tires; a second step of running the vehicle and measuring the state of the vehicle while it is running; The second step is a steady circular turning step of making the vehicle turn at a constant speed while keeping the steering angle constant; a deceleration step of inducing a tuck-in of the vehicle by applying a longitudinal deceleration to the vehicle while maintaining the steering angle from the steady circular turning state; measuring at least a yaw rate of the vehicle from the steady-state turning step to the deceleration step; an evaluation step of evaluating a tuck-in characteristic of the vehicle based on the yaw rate; A method for evaluating the tuck-in characteristics of a vehicle, including: [Invention 2] The method for evaluating the tuck-in characteristics of a vehicle according to the first aspect of the present invention, wherein the lateral acceleration of the vehicle during the steady circular cornering is equal to or less than the limit lateral acceleration of the tire. [Invention 3] The lateral acceleration of the vehicle is 8 to 11 m / s 2 The method for evaluating the tuck-in characteristics of a vehicle according to the present invention 1 or 2, wherein the range is [Invention 4] 4. The method for evaluating the tuck-in characteristics of a vehicle according to any one of claims 1 to 3, wherein the turning radius during the steady circular cornering is in the range of 60 to 120 m. [Invention 5] The deceleration is 1.96 m / s 2 A method for evaluating the tuck-in characteristics of a vehicle according to any one of Inventions 1 to 4, which is as follows: [Invention 6] 5. The method for evaluating a tuck-in characteristic of a vehicle according to any one of claims 1 to 4, wherein the deceleration step involves releasing the accelerator pedal of the vehicle. [Invention 7] The method for evaluating the tuck-in characteristics of a vehicle according to any one of the present inventions 1 to 6, wherein the measuring step further measures at least one of the vehicle's traveling speed, the vehicle's steering angle, the vehicle's accelerator opening, the vehicle's longitudinal acceleration, or the vehicle's lateral acceleration. [Explanation of symbols]

[0038] 1 vehicle S2 Second step S21 Steady circular turning step S22 Deceleration step S23 Measurement step S24 Evaluation Step

Claims

1. A method for evaluating tuck-in characteristics of a vehicle, comprising: A first step of providing a vehicle equipped with tires; a second step of running the vehicle and measuring the state of the vehicle while it is running; The second step is a steady circular turning step of making the vehicle turn at a constant speed while keeping the steering angle constant; a deceleration step of inducing a tuck-in of the vehicle by applying a longitudinal deceleration to the vehicle while maintaining the steering angle from the steady circular turning state; measuring at least a yaw rate of the vehicle from the steady-state turning step to the deceleration step; an evaluation step of evaluating a tuck-in characteristic of the vehicle based on the yaw rate; A method for evaluating the tuck-in characteristics of a vehicle, including:

2. 2. The method for evaluating the tuck-in characteristics of a vehicle according to claim 1, wherein the lateral acceleration of the vehicle during the steady-state circular cornering is equal to or less than a limit lateral acceleration of the tire.

3. The lateral acceleration of the vehicle is 8 to 11 m / s ２ 3. The method for evaluating the tuck-in characteristics of a vehicle according to claim 2, wherein the range is

4. 2. The method for evaluating the tuck-in characteristics of a vehicle according to claim 1, wherein the turning radius during the steady circular cornering is in the range of 60 to 120 m.

5. The deceleration is 1.96 m / s ２ 5. The method for evaluating the tuck-in characteristics of a vehicle according to claim 1, wherein:

6. 5. The method for evaluating the tuck-in characteristics of a vehicle according to claim 1, wherein the deceleration step includes releasing an accelerator pedal of the vehicle.

7. 5. The method for evaluating the tuck-in characteristics of a vehicle according to claim 1, wherein the measuring step further measures at least one of a speed of the vehicle, a steering angle of the vehicle, a longitudinal acceleration of the vehicle, a lateral acceleration of the vehicle, or an accelerator opening of the vehicle.

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