JP2011207424A - Suspension specification evaluation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine the specification of a suspension model having excellent steering stability based on the practically applicable non-linear suspension characteristic.SOLUTION: A vehicle model setting unit 11 builds a vehicle model, and builds a front wheel suspension model and a rear wheel suspension model for each of the plurality of specification data. A roll mode analyzing unit 12 obtains the pitch rate at the roll angle zero to be applied to the vehicle model as a substitute of the roll mode for each combination of the front and rear wheel suspension models for each specification. The substitute roll mode selects the combination of the suspension specification indicating the characteristic closest to zero as the suspension model having excellent steering stability.

Description

  The present invention relates to a suspension specification evaluation apparatus that selects an optimum combination from a combination of suspensions of a plurality of front wheels and rear wheels having different specifications.

  A suspension provided in a vehicle such as an automobile includes a suspension spring and a damper (shock absorber), a function of buffering vibration transmitted from the wheel to the vehicle body side, and a function of pressing the wheel against the road surface. With these functions, ride comfort and steering stability are ensured.

  Here, a general vehicle behavior when the vehicle travels on a curved road will be briefly described. When the vehicle enters the curved road, first, the driver decelerates by braking. Then, a forward pitch motion is generated in the vehicle, a compressive load is applied to the suspension spring provided in the suspension on the front wheel side, and a tensile load is applied to the suspension spring of the rear wheel side suspension. Further, while the vehicle is turning on a curved road, a lateral acceleration due to the centrifugal force is generated in the vehicle, and therefore, a rolling motion that is inclined outward in the turning direction is generated in the vehicle. Therefore, a compressive load is applied to the suspension spring outside the turning, and a tensile load is applied to the suspension spring inside the turning. Thereafter, when the driver starts accelerating near the end of the curved road, a pitch motion that rises forward is generated in the vehicle. Therefore, a tensile load is applied to the suspension spring on the front wheel side, and a compressive load is applied to the suspension spring on the rear wheel side. Therefore, in the slalom traveling that travels while turning back the steering on the continuous curved road, the vehicle behavior is such that the roll motion and the pitch motion are repeated in a complex manner. Moreover, the vibration accompanying this roll driving | operation and pitch motion is suppressed by the damping effect | action of the damper provided in each suspension.

  This vehicle behavior largely depends on the specifications of the suspension model (suspension specifications), and the steering stability can be improved by changing the suspension specifications. Conventionally, this suspension specification is determined by the sensitivity of a test driver who performs a running test.

  However, in order for a test driver to perform a running test, it is necessary to prepare multiple vehicles with different suspension specifications and check the running of all the vehicles. It takes time to determine the final specifications. There is a disadvantage that development is delayed.

  By the way, the phase difference (roll mode) between the tilt angle in the horizontal direction (roll angle) due to the roll motion and the tilt angle (pitch angle) in the front-rear direction due to the pitch motion is brought close to zero, that is, the roll motion and the pitch motion It is known that the steering stability is improved by synchronizing the generation timing. Therefore, if suspension specifications that bring the roll mode closer to zero have been determined to some extent at the design stage, the suspension specifications will be narrowed down, reducing the time required for running tests and greatly reducing development costs. it can.

  As a technique for determining suspension specifications to some extent at the design stage, for example, in Patent Document 1 (Japanese Patent Laid-Open No. 2007-8373), the roll mode becomes zero by using a theoretical formula in consideration of the roll mode at the time of design. A technique for determining such a suspension specification is disclosed.

JP 2007-8373 A

  By the way, the steering pattern for continuously turning the steering, such as in the case of slalom running, is different for each driver, and the characteristics of the suspension of the same specification are different for each steering pattern. Ideally, a suspension specification in which the roll mode is zero in all steering patterns is preferable, but it is difficult in practice.

  In the technique disclosed in the above-mentioned document, only one set of suspension specifications is determined for one vehicle from the theoretical formula, so the suspension characteristics for each steering pattern are not taken into consideration. In the traveling test, traveling confirmation for each steering pattern is required. However, if a good evaluation cannot be obtained in the running test, the design must be performed again, resulting in an increase in development time.

  In addition, in the technology disclosed in the above-mentioned document, only one set of suspension specifications is determined for one vehicle. For example, there is a need to give priority to ride comfort at the expense of steering stability to some extent. In this case, it is not possible to select a suspension specification having characteristics in line with the needs, and there is a problem of lack of practicality.

  Furthermore, since the suspension specification is derived from the theoretical formula, this suspension characteristic becomes a linear characteristic. However, since the actual suspension characteristics are non-linear characteristics, it is not possible to sufficiently perform an analysis in line with the actual characteristics.

  In view of the above circumstances, the present invention obtains a roll mode based on actual non-linear suspension characteristics, and has a suspension specification with characteristics that meet user needs as well as a suspension specification with a roll mode characteristic close to zero. An object of the present invention is to provide a highly practical suspension specification evaluation apparatus.

  In order to achieve the above object, the present invention is based on the relationship between the roll angle and the pitch angle generated in the vehicle model at the time of steering based on the vehicle model data and the specification data of the suspension model installed in the vehicle model. In the suspension specification evaluation apparatus comprising analysis processing means for evaluating the specifications of the suspension model, the analysis processing means is configured to use the pitch rate when the roll angle is zero based on a Lissajous waveform represented by the roll angle and the pitch rate. Based on the above, the specification of the suspension model is evaluated.

  According to the present invention, the specification set for the suspension model is evaluated based on the Lissajous waveform represented by the roll angle and the pitch rate, and based on the pitch rate when the roll angle is zero. The phase difference between the roll angle and the pitch angle can be determined relatively easily on the basis of the actual non-linear suspension characteristics. In addition, by selecting the specifications of a suspension model having a characteristic in which the phase difference is close to zero, it is possible to specify a suspension that can obtain good steering stability for the current vehicle model.

  In addition, for example, by setting a pitch rate suitable for the user's preference when the roll angle is zero, and selecting a suspension model having a specification close to the preset pitch rate, the user's needs A suspension having characteristics suitable for the above can be set, and high practicality can be obtained.

Functional block diagram of suspension specification evaluation system Flow chart showing suspension specification evaluation process Schematic diagram of a vehicle equipped with a suspension Explanatory diagram showing suspension behavior when roll motion occurs (A) is a diagram showing a Lissajous waveform of roll angle and pitch angle, (b) is a diagram showing a Lissajous waveform of roll angle and pitch rate Chart showing the concept of the roll mode map A steering pattern that is a horizontal axis parameter of the roll mode map is shown, (I) is a timing chart showing a trapezoidal waveform steering pattern, (II) is a timing chart showing a trapezoidal sine waveform steering pattern, and (III) is a sine waveform steering pattern. (IV) is a timing chart showing a triangular waveform steering pattern The steering pattern at the time of changing the steering timing which is the parameter of the vertical axis | shaft of a roll mode map is shown, (a) is a timing chart which shows the steering timing of a phase advance state, (b) shows the steering timing of a normal phase state. Timing chart, (c) is a time chart showing the steering timing in the phase delay state Chart showing the concept of the roll mode tuning map Chart showing other roll mode tuning maps

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. A suspension specification evaluation apparatus 10 shown in FIG. 1 includes a CPU that executes suspension specification evaluation processing in accordance with a processing program stored in a ROM, which will be described later, a RAM that temporarily stores processing programs and intermediate processing data, a processing program, fixed data, and the like. It has a memory such as ROM to store, a large-capacity memory such as a hard disk to store various data, and based on the input vehicle model data and suspension specification data, the roll mode for each steering condition is determined by CAE (Computer Aided Engineering) To analyze.

  An input device 2 including a keyboard and a mouse is connected to the input side of the suspension specification evaluation device 10, and an output device 3 such as a monitor and a printer is connected to the output side. A suspension specification evaluation program is stored in advance in the memory of the suspension specification evaluation apparatus 10, and the CPU executes analysis processing according to the suspension specification evaluation program.

  Further, the CPU has a vehicle model setting processing unit 11, a roll mode analysis processing unit 12 as an analysis processing unit, and an output processing unit 13 for outputting calculation results as functions for executing suspension specification evaluation processing. Furthermore, the suspension specification evaluation apparatus 10 includes a database unit 14 that stores various data related to the vehicle, and a memory unit 15 that stores data calculated by the vehicle model setting processing unit 11 and the roll mode analysis processing unit 12. It has been. The database unit 14 and the memory unit 15 are constructed on the same readable / writable nonvolatile recording medium. Examples of the nonvolatile recording medium include a hard disk device, a magneto-optical disk device, and a flash memory.

  As shown in FIG. 3, the vehicle model setting processing unit 11 constructs a vehicle model 1 equipped with a suspension to be analyzed using various data of the vehicle and specifications of the front wheel suspension and the rear wheel suspension. A front wheel suspension model 21f and a rear wheel suspension model 21r are constructed using the data.

  The suspension models 21f and 21r are provided with dampers (shock absorbers) 22a and suspension springs 22b. As shown in FIG. 4, left and right unsprung members 25L and 25R provided in the front and rear, and springs It is interposed between the upper member 26. In the damper 22a, in order to achieve both riding comfort and vibration damping, the extension side and the compression side are set such that the extension side damping force is larger than the compression side damping force for the same damper stroke speed. ing. Therefore, when a roll motion is generated in the sprung member during the slalom running where the steering is continuously turned back, the damping force of the damper 22a of the extension-side unsprung member (left unsprung member 25L in the drawing) is reduced to the compression side. It becomes larger than the damping force of the damper 22a of the unsprung member (right unsprung member 25R in the figure). As a result, a force (pressing force) that pushes down the sprung member 26 is generated in the sprung member 26, and when this pressing force is different between the front and the back, a forward turning or a front rising pitch motion is generated. Therefore, this pitch motion is repeatedly generated during slalom traveling.

  In this embodiment, the front wheel suspension model 21f and the rear wheel suspension model 21r are constructed with different specifications, and the left and right suspension models 21f (21r) are constructed with the same specifications. These data are stored in advance in the database unit 14 for each specification.

  Each of the suspension models 21f and 21r has a plurality of specifications. First, a basic specification is set for the plurality of suspension models 21f and 21r, and a plurality of suspension models 21f and 21r having different specifications are set by performing parameter tuning stepwise on the basic specification.

  The roll mode analysis processing unit 12 is based on the vehicle model 1 constructed by the vehicle model setting processing unit 11 and the combination of the front wheel suspension model 21f and the rear wheel suspension model 21r subjected to parameter tuning for each steering condition. The roll mode [deg / sec] (the phase difference between the roll angle [deg] and the pitch angle [deg]) is analyzed to evaluate the roll feeling.

  As a means for calculating the roll mode, it is conceivable to calculate from the time series data. However, calculating the roll mode from time series data is difficult because the pitch motion and roll motion are non-linear motions, requiring enormous calculations. On the other hand, as shown in FIG. 5A, when the relationship between the roll angle and the pitch angle generated in the vehicle when traveling on a curved road is represented by a Lissajous waveform, the roll mode between the roll angle and the pitch angle is zero (phase difference). In the case of (none), the Lissajous waveform becomes a parabola as shown by a thick solid line, and the area becomes zero. In the case of roll mode detection (with phase difference), an area appears as shown by a thin line, and the roll mode can be obtained by calculating this area. However, calculating the roll mode one by one from the area for each Lissajous waveform takes more analysis time than necessary, increasing development time and development man-hours.

  By the way, as shown in FIG. 5B, when the relationship between the roll angle [deg] and the pitch rate [deg / sec] is shown by a Lissajous waveform, the convergence is proportional to the phase difference between the roll angle and the pitch angle. It can be seen that the pitch rate of the point P moves. The amount of movement of the convergence point P is substantially proportional to the roll mode. Therefore, the coordinates when the roll mode is zero are the origin (horizontal axis = 0, vertical axis = 0), and the roll angle is 0. By calculating the pitch rate, the roll mode can be calculated from this pitch rate instead. That is, the “roll mode that is the phase difference between the roll angle and the pitch angle” can be calculated by “pitch rate at zero roll angle” (hereinafter referred to as “substitute roll mode”). In FIG. 5, the roll angle + (plus) indicates left steering, − (minus) indicates right steering, the pitch angle + (plus) rises forward, and − (minus) indicates forward turning.

  The driver's steering timing and steering speed when continuously performing steering switching such as slalom running vary from driver to driver. In other words, the steering timing ranges from a type that returns slowly after performing a steering operation early to a type that returns quickly after turning at a slower timing, and further, from a type that prefers steering with a high steering speed to a slow steering. There are a wide variety of types that prefer to.

  Regardless of the steering conditions preferred by the driver, a suspension that can obtain a substantially satisfactory steering stability is said to have a specification (damping force) that makes the roll mode zero under each steering condition.

  In the present embodiment, as a method of evaluating the roll feeling for each steering condition, the vehicle model 1 is selected by selecting the suspension specification having the characteristic (damping force) closest to zero in each of the steering conditions. The suspension models 21f and 21r having the optimum specifications are identified. The steering timing is set by the phase difference between the steering input speed (steering speed) and the maximum steering angle.

  Specifically, as shown in FIG. 6, steering by a phase difference (steering peak phase difference) based on a steering pattern based on a steering speed on the horizontal axis and a maximum steering angle indicating an ideal sine waveform on the vertical axis. A steering condition is specified in a grid-like roll mode map that takes timing, and a roll feeling (feeling) for each steering condition with respect to one suspension specification is evaluated.

  As shown in FIG. 7, the horizontal axis of the grid-like roll mode map is different in the change characteristic of the steering speed as a typical steering pattern of the driver. (I) Trapezoid waveform, (II) Trapezoid Four types are set: sine waveform, (III) sine waveform, and (IV) triangular waveform. Further, on the vertical axis of this grid-like roll mode map, the phase at which the phase of the steering peak phase difference is advanced by + Δt with respect to the reference waveforms (a) and (b) from the fastest phase as the steering timing. Three types are set: a lead waveform, (b) a neutral reference waveform, and (c) a phase delay waveform whose phase is delayed by −Δt with respect to the reference waveform of (b). For example, when the reference waveform is the sine waveform shown in (III) of FIG. 7, the waveforms corresponding to the lattice points (III, a), (III, b), (III, c) in FIG. a) As shown in (b) and (c). In FIGS. 7 and 8, the + (plus) side is the left turning, and the − (minus) side is the right turning.

  Since the driver's steering condition can be expressed by a combination of the steering peak phase difference as the steering timing and the steering speed, the representative pattern of the steering speed on the vertical axis represented by the roll mode map shown in FIG. A typical driver's steering condition can be specified by a combination of the three types and four types of representative patterns of the steering peak phase difference on the horizontal axis, that is, any of the patterns related to 12 types of lattice points. In all of the specified steering conditions, the optimum suspension models 21f and 21r suitable for the vehicle model 1 can be specified by selecting a suspension specification in which the substitute roll mode exhibits characteristics closest to zero. The substitute roll mode between grid points is obtained by interpolation calculation. In the present embodiment, the substitute roll mode is classified according to the display pattern (or color) set for each region so that it can be easily recognized visually.

  In FIG. 9, basic specifications F1 and R1 of the front wheel suspension model 21f and the rear wheel suspension model 21r to be attached to the vehicle model 1 are set on the upper left, and parameters related to the suspension models 21f and 21r of the basic specifications F1 and R1 ( For example, the damping rate of the damper 22a) is tuned step by step, and the specifications of the front wheel suspension model 21f including the basic specifications F1 and 10 candidate specifications F1 to F10 are set as evaluation targets. As the specifications of the suspension model 21r, seven candidate specifications R1 to F7 including the basic specification R1 are set as evaluation targets. From the 70 candidate combinations, a combination of suspension models 21f and 21r having an optimal specification suitable for the vehicle model 1 is specified.

  Specifically, the suspension model evaluation process executed by the roll mode analysis processing unit 12 described above follows a suspension model evaluation routine shown in FIG.

  In this routine, vehicle data such as vehicle model data (vehicle specifications, etc.) and tire data (tire specifications, etc.) representing the behavior of the vehicle model 1 during travel are first input in step S1.

  Next, the process proceeds to step S2, and the specification data of the suspension model set for each candidate is input. This specification data is input for each suspension specification set in advance.

  Subsequently, it progresses to step S3 and it is determined whether there exists the next candidate. At this time, a message indicating whether or not there is a next candidate is displayed on the monitor provided in the output device of the suspension specification evaluation apparatus 10, and YES and NO selection buttons are displayed. If there is a next candidate and the operator clicks the YES button, the program returns to step S2 and a screen for inputting new candidate specification data is displayed.

  Further, in step S3, when all the specification data to be analyzed are input at this time, that is, 10 candidate specifications F1 to F10 for the front wheel suspension model 21f shown in FIG. 9 and 7 candidates for the rear wheel suspension model 21r. When all inputs of the specifications R1 to R7 are completed, the operator clicks NO on the selection button displayed on the monitor. Then, the program proceeds to step S4, executes a roll mode analysis for each candidate, and creates the roll mode map described above. In each roll mode map, the substitute roll mode obtained for each of the 12 types of steering conditions described above is displayed.

  Thereafter, the process proceeds to step S5, where the roll mode maps are assembled to create a roll mode tuning map as shown in FIG. 9. In step S6, the roll mode tuning map is stored in the memory unit 15, and the routine is executed. finish. The roll mode tuning map stored in the memory unit 15 can be output from the output device 3 such as a monitor or a printer via the output processing unit 13.

As described above, as the substitute roll mode is closer to zero, the suspension model 21f, 21r of the vehicle model 1 is an optimal combination. In the present embodiment, the substitute roll mode in this range is set to 0 ± 0.025. Therefore, the larger the area of the substitute roll mode (0 ± 0.025) in the entire roll mode map, the higher the evaluation value. This evaluation value may be expressed, for example, by the ratio shown in the substitute roll mode (0 ± 0.025) to the area of the entire roll mode map ([substitute roll mode (0 ± 0.025) area / roll mode map whole Area] × 100 [%]).
In addition, when it is desired that the vehicle on which the suspension to be evaluated is mounted have characteristics that meet specific needs, the road map is not evaluated with uniform weights, but is substituted under specific steering conditions. The area of the roll mode (0 ± 0.025) may be weighted so as to be evaluated relatively higher than the area of the substitute roll mode (0 ± 0.025) under other steering conditions. Alternatively, a road map may be created and evaluated only with specific steering conditions that meet the needs.

  Incidentally, in FIG. 9, the front wheel suspension model 21f side has the specifications F6 to F10, and the rear wheel suspension model 21r side has the specification R7 with an evaluation value of 85 to 95 {%}. Among a plurality of specifications, it can be said that this is an optimal combination capable of obtaining good steering stability. However, even if the front wheel suspension model 21f side has the specifications F6 to F9 and the rear wheel suspension model 21r side has the specifications R2 and R3, the evaluation value is in the range of 85 to 95 [%]. Can be obtained.

  Therefore, in consideration of this roll mode tuning map, one or a plurality of suspension models 21f and 21r having specifications that are considered to obtain good steering stability are selected, a vehicle equipped with them is actually driven, By adjusting, the final specification is determined.

  As described above, in this embodiment, the pitch rate (substitute roll mode) at the roll angle zero from the Lissajous waveform constituted by the roll angle and the pitch rate is changed to the roll mode (roll angle [deg] and pitch angle [deg]. Therefore, it is possible to obtain a specification based on the actual non-linear suspension characteristics relatively easily.

  Further, based on the substitute roll mode, the combination of the suspension models 21f and 21r that can obtain good steering stability can be specified by selecting the suspension specification having the characteristic that the substitute roll mode is closest to zero. .

  Further, when determining the specifications of the front wheel suspension model 21f and the rear wheel suspension model 21r equipped in one vehicle model, a roll mode map for each specification is used and based on the substitute roll mode indicated in the roll mode map. In addition, since the optimum suspension specification that matches one vehicle model 1 is selected, it is not necessary to run all kinds of combinations in actual vehicles, and the time required for development and the time required for running tests can be shortened. Development costs can be significantly reduced.

  Further, by referring to the roll mode tuning map, it is possible to roughly grasp the characteristics obtained by combining the suspension specifications of the front wheels and the rear wheels. Therefore, for example, it is possible to select a combination of suspension specifications that gives priority to ride comfort at the expense of steering stability to some extent. As a result, by using the suspension specification evaluation apparatus 10 according to the present embodiment, it is possible to select a suspension specification having characteristics that meet the user's needs at the design stage, and high practicality can be obtained.

  Further, in the roll mode tuning map of FIG. 9, for example, it is found from experience that good steering stability cannot be obtained by combining the specifications F1 to F5 of the front wheel suspension model 21f and the specifications R1 to R7 of the rear wheel suspension model 21r. If it is understood, the specifications F6 to F10 and the specifications R1 to R7 are used except for the specification, and further tuning is performed by subdividing these, and as shown in FIG. 10, a new front wheel suspension model 21f is obtained. A roll mode map composed of combinations of the specifications Fa to Ff and the specifications Ra to Rg of the rear wheel suspension model 21r may be created, and a roll mode tuning map may be created by collecting the roll mode maps. As a result, waste of time required for analysis is not only reduced, but suspension specifications can be set more precisely.

  The present invention is not limited to the above-described embodiment. For example, the combination of the specification of the front wheel suspension model 21f and the specification of the rear wheel suspension model 21r is comprehensively displayed as a roll mode tuning map. The roll mode map obtained for each specification may be displayed individually. Further, the obtained substitute roll mode may be displayed three-dimensionally on the roll mode map.

  Furthermore, in the above-described embodiment, the characteristics of the substitute roll mode are changed by changing the damper specifications (damping rate of the damper 22a), but the front and rear roll center heights are changed, or the specifications of the suspension springs are changed. The characteristics of the substitute roll mode may be changed by changing the specifications of both the damper and the suspension spring. Furthermore, there may be more than 12 types of steering conditions constituting the roll mode map.

1 ... Vehicle model,
10: Suspension specification evaluation device,
11 ... Vehicle model setting processing unit,
12 ... Roll mode analysis processing unit,
13 ... Output processing unit,
14 ... Database section
15 ... Memory part,
21f ... Front wheel suspension model,
21r ... rear wheel suspension model,
22a ... Damper,
22b ... suspension spring,
25L ... Left unsprung member,
25R ... right unsprung member,
26 ... sprung member,
F1-F10, R1-R7, Ra-Rg, Fa-Ff ... suspension specifications,
P: Convergence point

Claims (6)

Analysis processing means for evaluating the specifications of the suspension model based on the relationship between the roll angle and the pitch angle generated in the vehicle model at the time of steering based on the data of the vehicle model and the specification data of the suspension model installed in the vehicle model In the suspension specification evaluation apparatus comprising
The analysis processing means evaluates the specifications of the suspension model based on the pitch rate when the roll angle is zero based on a Lissajous waveform represented by the roll angle and the pitch rate. Evaluation device.   The suspension specification evaluation apparatus according to claim 1, wherein the plurality of steering conditions are set by a combination of a plurality of steering speeds set in advance and a phase difference at a plurality of steering peaks.   The steering model is specified by the plurality of steering speeds and the phase difference at the plurality of steering peaks, and the specification of the suspension model is evaluated for each of the specified driving conditions. Suspension specification evaluation device.   A map for specifying the steering condition is provided by the plurality of steering speeds and the phase difference at the plurality of steering peaks, and the map is provided for each specification of the suspension model, and is tuned by a set of maps for each specification. 4. The suspension specification evaluation apparatus according to claim 3, wherein a map is configured.   The suspension specification evaluation device according to any one of claims 1 to 4, wherein the analysis processing means is set such that an evaluation value is higher as the pitch rate is closer to zero.   6. The suspension specification evaluation apparatus according to claim 1, wherein the analysis processing unit has a plurality of steering conditions and evaluates the specification of the suspension model for each of the steering conditions.

Images