JP2012108768A - Suspension behavior estimation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately grasp a behavior of a suspension mechanism.SOLUTION: In a suspension behavior evaluation system, an analysis condition acquisition part acquires displacement of a wheel in a vertical direction in relation to a vehicle body and steering angle of the wheel, and a behavior estimation part calculates a first oscillation angle θ1 around a reference stud axis z of a ball joint 36 and a third oscillation angle θ3 around a reference vertical axis x of the ball joint 36 by utilizing the acquired displacement and steering angle of the wheel. The behavior estimation part calculates a second oscillation angle θ2 around a reference stabilizer link axis y of the ball joint 36 by utilizing the calculated third oscillation angle θ3 and estimates the behavior of the suspension mechanism by utilizing the calculated first oscillation angle θ1, the second oscillation angle θ2 and the third oscillation angle θ3.

Description

  The present invention relates to a suspension behavior estimation method, and in particular, a suspension having a stabilizer link that moves in association with a relative movement of a wheel and a vehicle body in the vertical direction, and a stabilizer bar that is connected to the stabilizer link via a ball joint. The present invention relates to a suspension behavior estimation method for estimating the behavior of a mechanism.

  In general, a suspension mechanism is provided around the wheel of the vehicle so as to allow a certain amount of displacement of the wheel in the vertical direction with respect to the vehicle body when the wheel rides on the unevenness of the road surface. Here, a technique has been proposed in which a model for behavior analysis of each part constituting the suspension is created, the motion of each part is displayed as an animation, and the interference data between the parts is determined using the shape data of each part ( For example, see Patent Document 1).

JP 2009-43208 A

  The suspension of an automobile has a mechanism that behaves up and down (bounds) in order to prevent the occupant from feeling the force (vibration) from the road surface during traveling. The front suspension has a mechanism for turning (steering) the tire for turning. In the suspension design, it is important to design the suspension parts to avoid interference between the suspension parts or the suspension body and the vehicle body (body) by the movement of the bound steer. In recent years, in order to prevent such interference, development of a technique for sufficiently confirming the configuration of the suspension mechanism 10 before trial manufacture has been advanced by simulation using CAE (Computer Aided Engineering). In order to appropriately respond to the recent demands for miniaturization of vehicles and shortening of the development period, there is an increasing demand for improvement in accuracy of interference evaluation by such CAE.

  As a calculation model for CAD analysis, there are cases where an actual model is created and a model that is simplified than the actual model, but in many cases, a model simplified than the actual model is used to shorten the analysis time. create. Even if the parts constrained at both ends by ball joints are modeled as they are, they are not sufficient for the interference check, and a model suitable for the interference check is required. At this time, it is necessary to avoid this problem by creating a model in which a part that does not actually move is moved to a “range that can move”.

  Therefore, the present invention has been made to solve the above-described problems, and an object thereof is to accurately grasp the behavior of the suspension mechanism.

  In order to solve the above-described problems, a suspension behavior estimation method according to an aspect of the present invention includes a stabilizer link that moves in association with a relative movement of a wheel and a vehicle body in a vertical direction, and is connected via the stabilizer link and a ball joint. In the suspension behavior estimation method for estimating the behavior of the suspension mechanism having the stabilizer bar, the step of obtaining the displacement of the wheel in the vertical direction relative to the vehicle body and the turning angle of the wheel, and the stud of the ball joint The center axis of the reference wheel is the reference stud axis, the straight line connecting both ends of the stabilizer link is the reference stabilizer link axis, and the axis perpendicular to both the reference stabilizer link axis and the reference stud axis is the reference vertical axis. Using the displacement and steering angle, the ball join A step of calculating a first swing angle θ1 around the reference stud axis and a third swing angle θ3 around the reference vertical axis of the ball joint, and using the calculated third swing angle θ3 The step of calculating the second swing angle θ2 around the reference stabilizer link axis of the ball joint and the calculated first swing angle θ1, second swing angle θ2, and third swing angle θ3 are used. And estimating the behavior of the suspension mechanism.

  According to this aspect, the behavior of the suspension mechanism can be estimated using the second swing angle θ2. For this reason, it is possible to accurately grasp the behavior of components such as the stabilizer link and the stabilizer bar, and it is possible to accurately estimate the behavior of the suspension mechanism.

  According to the present invention, the behavior of the suspension mechanism can be accurately grasped.

It is a figure which shows typically the structure of the suspension mechanism used as the object of the behavior estimation by the suspension behavior evaluation system (not shown) which concerns on this embodiment. It is sectional drawing of the connection part of a stabilizer bar and a stabilizer link. It is a figure which shows typically the relationship between a stabilizer link and a ball joint. It is a functional block diagram which shows the structure of the suspension behavior evaluation system which concerns on this embodiment. It is a flowchart which shows the suspension behavior estimation procedure which estimates the behavior of a suspension mechanism by the behavior estimation system which concerns on this embodiment. (A) And (b) is a figure which shows a ball joint and a ball joint when a stabilizer link axis | shaft is perpendicular | vertical to the paper surface. It is a figure which shows 2nd rocking | swiveling angle (theta) 2 when changing a bound behavior and a steer behavior according to the analysis time t. FIG. 8 is an enlarged view of the second swing angle θ shown in FIG. 7.

  Hereinafter, embodiments of the present invention (hereinafter referred to as “embodiments”) will be described in detail with reference to the drawings.

  FIG. 1 is a diagram schematically showing a configuration of a suspension mechanism 10 that is a target of behavior estimation by a suspension behavior evaluation system (not shown) according to the present embodiment. The suspension mechanism 10 includes a wheel 12, a steering knuckle 14, an upper control arm 16, a lower control arm 18, a rack bar 20, a tie rod 22, a ball joint 24, a ball joint 26, a stabilizer link 30, a stabilizer bar 32, a ball joint 34, and a ball. A joint 36 is provided.

  The steering knuckle 14 supports the wheel 12 rotatably through a steering hub (not shown). The upper control arm 16 has one end connected to the upper portion of the steering knuckle 14 and the other end connected to a vehicle body (not shown). The lower control arm 18 has one end connected to the lower portion of the steering knuckle 14 and the other end connected to the vehicle body. The upper control arm 16 and the lower control arm 18 support the steering knuckle 14 so as to be displaced in the vertical direction with respect to the vehicle body.

  One end of the tie rod 22 is connected to the steering knuckle 14 via a ball joint 24. The other end of the tie rod 22 is connected to the rack bar 20 via a ball joint 26.

  The rack bar 20 is connected to a steering wheel provided in the vehicle cabin via a rack mechanism (not shown) and a steering shaft (not shown), and the steering wheel is turned by the driver. To propel the vehicle in the left-right direction. Accordingly, the tie rod 22 is also propelled in the left-right direction of the vehicle, the steering knuckle 14 is rotated, and the wheels 12 are steered.

  A lower end of a stabilizer link 30 is connected to the lower control arm 18 via a ball joint 34. The upper end of the stabilizer link 30 is connected to one end of the stabilizer bar 32 via a ball joint 36. Hereinafter, a straight line connecting the swing center between the stabilizer link 30 and the ball joint 34 and the swing center between the stabilizer link 30 and the ball joint 36 is referred to as a stabilizer link shaft 30a.

  The lower control arm 18 is swingably connected to both the vehicle body and the steering knuckle 14 so that the vehicle body and the wheel can be relatively moved in the vertical direction. For this reason, the stabilizer link 30 attached to the lower control arm 18 relatively moves in the vertical direction with respect to the vehicle main body with the relative movement in the vertical direction between the vehicle main body and the wheels. By connecting the stabilizer bar 32 to the stabilizer link 30, the roll of the vehicle is suppressed by the stabilizer bar 32. Each of the upper control arm 16, the lower control arm 18, and the stabilizer bar 32 is connected to the vehicle body via a rubber bush 38.

  FIG. 2 is a cross-sectional view of a connecting portion between the stabilizer bar 32 and the stabilizer link 30. The ball joint 36 is formed in a shape in which a spherical ball portion 36a and a stud 36b extending in a truncated cone shape are integrally coupled. The stud 36b is provided such that a stud shaft 36c, which is a central shaft, passes through the center of the ball portion 36a. The ball portion 36a is connected to one end of the stabilizer link 30 so as to be rotatable within a predetermined range. The stud 36b is inserted and fixed in the mounting hole of the stabilizer bar 32. 2 indicates the allowable swing angle of the ball joint 36. The swing angle of the ball joint 36 with respect to the stabilizer link 30 is regulated within the allowable swing angle θmax.

  FIG. 3 is a diagram schematically showing the relationship between the stabilizer link 30 and the ball joint 36. In the present embodiment, the position in the vertical direction of the wheel 12 with respect to the vehicle main body when the vehicle is stopped is set as the reference position. Here, the center axis of the stud 36b of the ball joint 36 connected to the stabilizer bar 32 when the vehicle is stopped on a horizontal road surface and the steering angle is zero degrees is defined as a reference stud axis z. Further, a straight line connecting both ends of the stabilizer link 30 at this time, that is, the stabilizer link shaft 30a is defined as a reference stabilizer link shaft y. Further, an axis orthogonal to both the reference stabilizer link axis y and the reference stud axis z is defined as a reference vertical axis x.

  The swing angle of the ball joint 36 around the reference stud axis z is the first swing angle θ1, the swing angle of the ball joint 36 around the reference stabilizer link axis y is the second swing angle θ2, and the reference vertical axis The swing angle of the ball joint 36 around x is a third swing angle θ3. The angle formed by the reference stud shaft z and the stud shaft 36 c is the swing angle θ of the ball joint 36.

  FIG. 4 is a functional block diagram showing the configuration of the suspension behavior evaluation system 50 according to the present embodiment. The suspension behavior evaluation system 50 includes a PC 52 and a display 54 connected to the PC 52. The PC 52 includes a CPU that executes various arithmetic processes, a ROM that stores various control programs, and a RAM that is used as a work area for data storage and program execution.

  The PC 52 incorporates behavior estimation software for estimating the behavior of each part constituting the suspension mechanism 10. In FIG. 4, the PC 52 depicts functional blocks realized by cooperation with hardware such as a CPU, ROM, and RAM, and this behavior estimation software. These functional blocks can be realized in various forms by a combination of hardware and software.

  The PC 52 includes a model construction unit 56, an analysis condition acquisition unit 58, a behavior estimation unit 60, and a display control unit 62. The model construction unit 56 constructs an analysis model of the suspension mechanism 10. The analysis condition acquisition unit 58 acquires behavior analysis conditions necessary for behavior analysis of the suspension mechanism 10 input by the user using an input device such as a mouse or a keyboard. The behavior estimation unit 60 estimates the behavior of each component constituting the suspension mechanism 10. The display control unit 62 displays the estimated behavior of the suspension mechanism 10 on the display 54.

  FIG. 5 is a flowchart showing a suspension behavior estimation procedure for estimating the behavior of the suspension mechanism 10 by the behavior estimation system according to the present embodiment. First, for example, a connection point between the upper control arm 16 and the lower control arm 18 and the steering knuckle 14, a connection point between the lower control arm 18 and the stabilizer link 30, a connection point between the stabilizer link 30 and the stabilizer bar 32, and a rubber bush 38. Various data specifying the specifications of the suspension mechanism 10 including the size, position, and material of each part, such as the characteristics of the stabilizer, the positions of both ends of the stabilizer link 30, and the axial direction of the ball joint 36, are input to the PC 52 by the user. The The stabilizer link shaft 30a is defined as a straight line connecting the positions of both ends of the stabilizer link 30 as described above. The model construction unit 56 constructs an analysis model of the suspension mechanism 10 using these data (S10).

  Further, when a behavior analysis condition such as a bound behavior or a steering behavior is input by the user (S12), the analysis condition acquisition unit 58 acquires the behavior analysis condition. Here, the bounce behavior refers to the vertical displacement of the suspension mechanism 10 with respect to the vehicle body from the reference position. Further, the steering behavior refers to the turning angle of the wheel 12. In S12, the user also inputs the allowable swing angle θmax and the allowable turning angle φmax of the ball joint 36.

  When the analysis model is thus constructed and the behavior analysis conditions are acquired, the behavior estimation unit 60 executes the behavior analysis of the suspension mechanism 10 using the constructed analysis model and the acquired behavior analysis conditions (S14).

  Here, in this behavior analysis, the behavior estimation unit 60 uses the obtained displacement of the wheel 12 and the turning angle to obtain the first swing angle θ1 around the reference stud axis z of the ball joint 36, the ball joint, First, a third swing angle θ3 around the reference vertical axis x is calculated. Since the calculation method of these 1st rocking angle (theta) 1 and 3rd rocking angle (theta) 3 is well-known, description is abbreviate | omitted. When the first swing angle θ1 and the third swing angle θ3 are calculated, the behavior estimation unit 60 uses the calculated third swing angle θ3 to rotate the ball joint 36 around the reference stabilizer link axis y. The second swing angle θ2 is calculated.

  Specifically, the behavior estimation system

To calculate the second swing angle θ2. This equation represents the swing angle θ of the stud shaft 36c with respect to the reference stud shaft z using the second swing angle θ2 and the third swing angle θ3, and can be derived by modifying this.

  Thus, in the suspension behavior evaluation system 50 according to the present embodiment, the behavior of the suspension mechanism 10 is estimated in consideration of the second swing angle θ2. As a result, it is possible to accurately grasp the behavior of components such as the stabilizer link 30 and the stabilizer bar 32, and it is possible to grasp the behavior of the suspension mechanism 10 more accurately.

  Here, the constraint condition regarding the behavior of the steering is examined. First, the movement of the ball joint 36 at both ends of the stabilizer link 30 will be examined. When considered on one side alone, the above formula is established for both ends. However, if the rotation is performed without considering the relationship between both ends, the allowable swing angle θmax at the other end may be exceeded. Therefore, by providing the following constraint conditions for behavior, analysis can be performed under conditions that do not exceed the allowable swing angle at both ends.

  So far, the first swing angle θ1, the second swing angle θ2, and the third swing angle θ3 related to the ball joint 36 interposed between the stabilizer link 30 and the stabilizer bar 32 have been described. When the swing angle of the ball joint 34 interposed between the stabilizer link 30 and the lower control arm 18 is φi, the following equation is established for φi.

この式におけるφｉ２は、ボールジョイント３４の挙動揺動角である。ボールジョイント３６の動きに合わせてスタビライザリンク３０も動くと仮定すると、φｉ２は、その動いた角度分を含んだ量にする必要がある。この点に着目すると、許容揺動角を超えた挙動の推定を回避するためには、以下の式を満たす必要がある。この値を解析に用いることにより、両端の許容揺動角を考慮した解析が可能となる。

Φi2 in this equation is the behavior swing angle of the ball joint 34. Assuming that the stabilizer link 30 also moves in accordance with the movement of the ball joint 36, φi2 needs to be an amount including the moved angle. Focusing on this point, it is necessary to satisfy the following equation in order to avoid estimation of behavior exceeding the allowable swing angle. By using this value for the analysis, it is possible to analyze in consideration of the allowable swing angle at both ends.

  This will be specifically described with reference to FIGS. 6 (a) and 6 (b). FIGS. 6A and 6B are views showing the ball joint 34 and the ball joint 36 when the stabilizer link shaft is oriented perpendicularly to the paper surface. The state where the ball joint 36 has rotated θ0i from the initial state shown in FIG. At this time, assuming that the stabilizer link 30 also rotates together, the ball joint 34 also rotates by φ0i which is the same value as θ0i. Here, when θ2i ≦ φ2i−φ0i, θ2i is used as it is. When θ2i> φ2i−φ0i, θ2i = φ2i−φ0i. Thereby, it is possible to analyze so as not to exceed the allowable swing angle at both ends of the stabilizer link 30.

  Further, the behavior estimation unit 60 estimates the direction and position of the wheel 12 using the calculated first swing angle θ1, second swing angle θ2, and third swing angle θ3 of the ball joint 36. . Using the estimated direction and position of the wheel 12 as described above, for example, it is possible to perform a gap evaluation as to whether a sufficient gap is provided so that components around the wheel 12 and the wheel 12 do not interfere with each other. Become.

  FIG. 7 is a diagram illustrating the second swing angle θ2 when the bound behavior and the steer behavior are changed according to the analysis time t. In the bound behavior, for example, as the analysis time t elapses, the vertical displacement of the wheel 12 with respect to the vehicle body can be changed stepwise multiple times. In the example shown in FIG. 7, as the analysis time t elapses, the bound behavior is increased over three stages from minus A, zero, and plus A. In FIG. 7, in the bound behavior, the direction in which the wheel 12 is displaced upward from the reference position due to the vehicle riding on the convex portion is defined as the plus direction.

  Further, in the steering behavior, for example, as the analysis time t elapses, the turning angle of the wheel 12 can be changed stepwise over a plurality of times. In the example shown in FIG. 7, the turning angle of the wheel 12 is changed stepwise over one period from minus B to plus B during a period in which the bound behavior is constant. In FIG. 7, in the steering behavior, the turning angle of the wheel 12 when the vehicle turns to the right is set to the plus direction.

  Thus, by changing the bounce behavior and the steering behavior, the combination of the displacement in the vertical direction of the wheel 12 with respect to the vehicle body and the turning angle of the wheel 12 can be periodically changed. The behavior estimation unit 60 calculates the second swing angle θ2 using the bounce behavior and the steering behavior acquired in this way.

  FIG. 8 is an enlarged view of the second swing angle θ2 shown in FIG. The behavior estimation unit 60 calculates the second swing angle θ2 when the bound behavior and the steering behavior are the i-th (i is a natural number) combination. In FIG. 8, the second swing angle θ2 at this time is shown as a second swing angle θ2i. Specifically, the behavior estimation unit 60 calculates the third swing angle θ3i when the bound behavior and the steering behavior are the i-th combination, and applies the second swing angle θ2i to the above formula to determine the second swing angle θ2i. calculate.

  Returning to FIG. When the behavior analysis is executed, the display control unit 62 uses the data input by the user for constructing the analysis model to determine the 3D (three-dimensional) shape of the wheel 12 and the parts around the wheel 12. The created and arranged image is displayed on the display 54 (S16). Next, the display control unit 62 displays the result of the behavior analysis by the behavior estimation unit 60 on the display 54 while changing i, which is the order of the combination of the bound behavior and the steering behavior, from 1 (S18). Since such an animation display method is known, the description thereof is omitted. The user sees this animation display and determines whether there is suspension mechanism 10 interference (S20). When it is determined that there is no interference (N in S20), the user proceeds to the next step such as creating a drawing of each component constituting the suspension mechanism 10 (S22).

  As described above, in this embodiment, whether or not there is interference is determined by visual observation by the user, but is not limited to this. For example, the behavior estimation unit 60 may determine whether interference has occurred between components using the shape and position of each component constituting the suspension mechanism 10 and the estimated behavior of each component. Since the technique for determining interference by a computer without using visual observation is well known, description thereof is omitted.

  If it is determined that there is interference (Y in S20), the processing in this flowchart is terminated. The user changes the shape of the parts as necessary, changes the suspension behavior condition and the allowable swing angle θmax of the ball joint 36, or the attachment position of the upper control arm 16 and the lower control arm 18 and the characteristics of the rubber bush 38. After changing the specifications of the suspension, etc., the process starts again from S10.

  In the foregoing, the behavior estimation method of the suspension mechanism 10 using the swing angle between the stabilizer link 30 and the ball joint 36 has been described. However, it goes without saying that the behavior estimation method of the suspension mechanism 10 is not limited to the method using the swing angle between the stabilizer link 30 and the ball joint 36.

  In the behavior estimation method of the suspension mechanism 10 described above, the swing angle θ of the ball joint 36 is calculated using the first swing angle θ1, the second swing angle θ2, and the third swing angle θ3. Of course, it is not limited to such a calculation method. For example, instead of any of the first swing angle θ1, the second swing angle θ2, and the third swing angle θ3, a user-defined joint whose motion is defined by a mathematical expression may be used. Since such user-defined joints are well known, detailed description thereof will be omitted.

  For example, instead of each of the first swing angle θ1, the second swing angle θ2, and the third swing angle θ3, different user-defined joint 1, user-defined joint 2, and user-defined joint 3 may be used. Good. Alternatively, a user-defined joint 4 may be used instead of each of the first swing angle θ1 and the second swing angle θ2, and a user-defined joint 5 may be used instead of the third swing angle θ3. You may use for each of the joints around a plurality of axes.

  The present invention is not limited to the above-described embodiment, and an appropriate combination of the elements of this embodiment is also effective as an embodiment of the present invention. Various modifications such as various design changes can be added to the present embodiment based on the knowledge of those skilled in the art, and the embodiments with such modifications can be included in the scope of the present invention.

  10 suspension mechanism, 12 wheels, 14 steering knuckle, 16 upper control arm, 18 lower control arm, 20 rack bar, 22 tie rod, 24 ball joint, 26 ball joint, 30 stabilizer link, 30a stabilizer link shaft, 32 stabilizer bar, 34 , 36 Ball joint, 36a Ball part, 36b Stud, 36c Stud shaft, 38 Rubber bush, 50 Suspension behavior evaluation system, 52 PC, 54 Display, 56 Model construction part, 58 Analysis condition acquisition part, 60 Behavior estimation part, 62 Display Control unit.

Claims (1)

In a suspension behavior estimation method for estimating the behavior of a suspension mechanism having a stabilizer link that moves with relative movement in the vertical direction between a wheel and a vehicle body, and a stabilizer bar that is connected to the stabilizer link via a ball joint,
Obtaining a displacement of the wheel in a vertical direction relative to a vehicle body, and a turning angle of the wheel;
When the center axis of the ball joint stud is the reference stud axis, the straight line connecting both ends of the stabilizer link is the reference stabilizer link axis, and the axis perpendicular to both the reference stabilizer link axis and the reference stud axis is the reference vertical axis Then, using the obtained wheel displacement and turning angle, a first swing angle θ1 about the reference stud axis of the ball joint and a third swing angle θ3 about the reference vertical axis of the ball joint are obtained. A calculating step;
Calculating a second swing angle θ2 about the reference stabilizer link axis of the ball joint using the calculated third swing angle θ3;
Estimating the behavior of the suspension mechanism using the calculated first swing angle θ1, second swing angle θ2, and third swing angle θ3;
A suspension behavior estimation method comprising:

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