JP2008076287A - Simulation method of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simulation method of vehicle for developing efficiently tires suited to vehicles. <P>SOLUTION: An experiment step measuring tire property, a step identifying results of the experiment step as parameters of tire property to develop a nonlinear identifying model, a step developing a mechanism analytic model for vehicles and their suspension, a step developing a full vehicle model by combining the nonlinear identifying model and the mechanism analytic model, and a step implementing virtual vibration calculation using the full vehicle model are implemented. Therefore, it becomes possible to implement vibration simulations of vehicles including nonlinear tires with a high degree of accuracy, experiment man-hour is reduced significantly as roughcast screening is available prior to doing shakedown by attaching trial products to real vehicles, and reduction can be achieved of development period. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle simulation method for efficiently developing a tire suitable for a vehicle.

  Vehicle undercarriage development is carried out at the final stage of vehicle development, and in order to develop tires suitable for prototype vehicles, based on the data of tires of the same grade manufactured in the past, etc. Considering the opinions of the evaluation driver, the prototype has been repeated empirically, and the specification has been determined through sensory evaluation and instrument measurement tests by running a vehicle with tires actually mounted.

  In particular, for ride comfort, sensory evaluation according to conditions such as vehicle speed is performed on some specified specific road surfaces, or vertical acceleration near the driver's seat is measured, and the measured vertical acceleration is reduced. Development was carried out in the process of correcting the rigidity of the tire in such a direction, and this required a lot of development man-hours.

  In recent years, with the development of computer technology, computer simulation is being used to reduce man-hours for prototyping and experiments. In terms of improving ride comfort performance, development efficiency has been improved through vibration simulations aimed at minimizing the vertical acceleration of the vehicle.

  However, with conventional spring-mass modeling, there is no effective method for reproducing non-linear characteristics such as amplitude dependence and frequency dependence among the vibration characteristics of tires, dampers and rubber bushes. Therefore, the consistency with the experimental results is poor and high accuracy cannot be realized. In addition, tire modeling includes a finite element model in which mesh is divided into finite elements including the shape, but the modeling itself takes time and also requires time for calculation, reducing the overall man-hours. There is inconvenience that does not lead to.

  An object of the present invention is to provide a vehicle simulation method for efficiently developing a tire suitable for a vehicle.

A vehicle simulation method according to the present invention includes:
An experimental step to measure the characteristics of the tire;
Identifying the result of the experimental step as a tire characteristic parameter and creating a nonlinear identification model;
Creating a mechanism analysis model of the vehicle and its suspension;
Creating a full vehicle model by combining the nonlinear identification model and the mechanism analysis model;
And performing a virtual excitation calculation using the full vehicle model.

  According to the present invention, it is possible to perform a vibration simulation of a vehicle including a non-linear tire with high accuracy, and to enable rough screening before a prototype is mounted on an actual vehicle and a running test is performed. The number of experiment steps can be greatly reduced, and therefore the development period can be shortened. As a result, a tire suitable for the vehicle can be efficiently developed.

Preferably, the experimental step also measures the properties of the damper and the rubber bush,
As the non-linear identification model, an experimental non-linear tire model, an experimental non-linear damper model, and an experimental non-linear rubber bush model are created, and the tire is pressed in the experiment step.

Embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a flowchart of a vehicle simulation method according to the present invention. In this flowchart, an experimental step for measuring characteristics of the tire, the damper, and the rubber bush is performed after the tire, the damper, and the rubber bush are made as trial products.

  In order to realize a highly accurate simulation, it is important how to obtain accurate input / output data that reproduces the real characteristics in experiments. In particular, in the creation of a tire model, which will be described later, it is necessary to devise an experimental site in order to accurately extract the characteristics of vertical vibration caused by different tires.

  The vibration related to the ride comfort is a low frequency region of about 1 to 30 Hz. An excitation test using a random wave that covers the amplitude when traveling on a road surface that is symmetrical with the frequency band is performed. At this time, since the amplitude of the damper and the amplitude of the bush change according to the mounting position in the vehicle, appropriate values are selected.

  For tires, if the part to apply vibration is a flat surface (flat pressing), offset line pressing, vertical line pressing, round pressing, side pressing and multiple point pressing (Fig. 2), there is no difference in the tire deformation mode. It is hard to be affected by the hardness of the belt (Fig. 3). For this purpose, it is desirable to apply vibration (line pressing) using a battlefield protrusion across the width direction of the tire in order to more clearly show the difference in vertical vibration characteristics (FIG. 2). In FIG. 2, the pressed portion is indicated by hatching.

  The experimental results obtained in the experimental step are identified as parameters of the tire, damper, and rubber bush, and an experimental nonlinear tire model, experimental nonlinear damper model, and experimental nonlinear rubber bush model are created as nonlinear parameter identification models. The nonlinear parameter identification model is a model that applies random vibration including the amplitude and frequency range of vibrations that are problematic in actual road surface running conditions on a bench test machine to the tire, damper and rubber bush to be modeled. This is an Empirical model in which the relationship between input and output obtained at that time is measured, and nonlinear parameters are identified using a neural network. Further, the experimental nonlinear tire model created here is a one-way model that reproduces only the vibration characteristics in the vertical direction, and does not consider tire rolling, front-rear force, left-right force, and the like.

  After creating the nonlinear parameter identification model, a mechanism analysis model of the vehicle and its suspension is created using the experimental nonlinear damper model and the experimental nonlinear rubber bush model. The mechanism analysis model is a link model in which a suspension arm is represented by a rigid body. Each part of the link model has weight, inertia, etc., and is expressed by putting elastic elements having restraint conditions and non-linearity of the rubber bush at the joints of the arms. Further, elastic deformation can be taken into account by using an arm or the like as a finite element model.

  After creating the mechanism analysis model, a full vehicle model is created by combining the vehicle model and the mechanism analysis model. As the vehicle model, a model capable of considering elastic deformation such as a finite element model can be preferably used. In this case, a sprung model is created in consideration of the weight and inertia of the engine, steering, etc., and a suspension and tires are attached to this to form a full vehicle model. After creating a full vehicle model, an excitation simulation step and pre-screening are performed.

The present invention is not limited to the above-described embodiment, and many changes and modifications can be made.
For example, in the above embodiment, the experimental nonlinear tire model, the experimental nonlinear damper model, and the experimental nonlinear rubber bush model are created. However, the present invention can be applied to the case where only the experimental nonlinear tire model is created. .

3 is a flowchart of a vehicle simulation method according to the present invention. It is a figure which shows how to push the tire in the case of a tire vibration experiment. It is a figure which shows the difference in the tire characteristic by how to push a tire.

Claims (3)

An experimental step to measure the characteristics of the tire;
Identifying the result of the experimental step as a tire characteristic parameter and creating a nonlinear identification model;
Creating a mechanism analysis model of the vehicle and its suspension;
Creating a full vehicle model by combining the nonlinear identification model and the mechanism analysis model;
And a step of performing virtual excitation calculation using the full vehicle model. The experimental step also measures the properties of the damper and rubber bush,
2. The vehicle simulation method according to claim 1, wherein an experimental nonlinear tire model, an experimental nonlinear damper model, and an experimental nonlinear rubber bush model are created as the nonlinear identification model.   3. The vehicle simulation method according to claim 1, wherein the tire is pressed in the experiment step.

Images