JPH06265441A - Setting method of running resistant load - Google Patents

Abstract

PURPOSE:To facilitate the measurement of running resistance in various automobiles as well as to reproduce the share ratio of front rear wheels in various chassis dynamometers in accurate manner. CONSTITUTION:At the time of controlling each running resistance of both front and rear wheels of a test car 1 with each absorption torque of two dynamometers 3F and 3R, a mechanical loss in reach mechanical system is measured by a coasting time measuring part 18, setting each to two mechanical loss compensating parts 15F and 15R, and the running resistance to be found out by means of coasting time measurement on a road is set to a running resistant load setting part 16, while an air resistant portion out of the running resistance and allocation of both front and rear wheels are obtained in a running resistance adjustment and distribution part 17 from a centroidal position of the car, thereby distributing each running resistance to each side of both these front and rear wheels.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chassis dynamometer for conducting a simulated running test of an automobile, and more particularly to a method of setting a running resistance load for testing a four-wheel drive vehicle.

[0002]

2. Description of the Related Art In a simulated driving test using a chassis dynamometer, front and rear wheels 1F and 1R of a test vehicle 1 are placed on rollers 2F and 2R, respectively, as shown in FIG. , 2R are respectively coupled with dynamometers 3F, 3R as power absorbing means and flywheels 4F, 4R for giving an inertial component of the vehicle under test 1, and the absorption torque and speed of the dynamometers 3F, 3R are converted into a power converter 5F, 5
Control with R.

The control of the dynamometers 3F and 3R is adjusted by controlling the output current of the power converters 5F and 5R by obtaining a current command corresponding to the running resistance value and the braking speed of the vehicle under test 1 by the control device 6.

The programmable controller 7 controls the speed and throttle opening and controls the operation of the transmission and the clutch in accordance with the running pattern of the vehicle under test 1, and controls the controller 6.
Is given a switching command for traveling resistance control or speed control.

The traveling resistance control by the control device 6 is performed by the dynamometers 3F, 3F in order to apply a load equivalent to traveling on the road.
Control the torque of R as a function of speed.

The running resistance consists of rolling resistance, gradient resistance, air resistance and inertial resistance, and is given based on the following equation.

[0007]

## EQU1 ## R = A + Wsin θ + BV ² + CdV / dt where A, B, C; constant determined by the shape of the car W; vehicle weight θ; road slope angle V; speed dV / dt; acceleration / deceleration Conventionally, there is a coasting method in which a vehicle is coasted on a test course or the like, constants A, B, and C for each speed section are obtained from the coasting time and speed, and a running resistance corresponding to the speed is calculated during a test. Mostly adopted.

The running resistance setting in the chassis dynamometer is set to compensate for the mechanical loss of the chassis dynamometer.

[0009]

The conventional running resistance setting method has a history for FF vehicles and FR vehicles, and is evaluated as an almost established technology.

However, in a four-wheel drive vehicle, how to distribute the running resistance to the front wheels and the rear wheels is an important issue in reproducing the running resistance during actual running.

That is, four-wheel drive vehicles are diversified in drive system such as center diff (full-time), part-time, a system for connecting front and rear wheels by viscous coupling, and a system for controlling drive force sharing of front and rear wheels. Therefore, it is necessary to set the traveling resistance load according to the drive system.

The chassis dynamometer itself also has a structure in which the left and right axles of the front wheels are directly connected to the left and right axles of the rear wheels, the front and rear axles are independent of each other, and the four wheels are independent of each other. In place of the flywheel, the dynamometer provides electric inertia, and the traveling resistance must be set according to the combination of these structures and the drive system of the four-wheel drive vehicle.

In particular, in a four-wheel drive vehicle, the friction loss between the front wheels and the rear wheels may not be independently measured depending on the transmission mechanism between the front wheels and the rear wheels, which may make it difficult to distribute the front wheels and the rear wheels. .

Even in such a case, there is a demand for a chassis dynamometer capable of performing an evaluation test by grasping the total friction loss including the mechanical loss without processing the test vehicle, particularly the completed vehicle.

An object of the present invention is to provide a running resistance load setting method which facilitates measurement of running resistance of various automobiles and which is applied to various chassis dynamometers to accurately reproduce the front-rear wheel sharing ratio. is there.

[0016]

In order to solve the above-mentioned problems, the present invention connects a pair of dynamometers to the front and rear wheels of a vehicle under test through rollers, respectively, to improve the running resistance of the vehicle. In a chassis dynamometer for performing a simulated running test by setting the absorption torque of the dynamometer respectively, a mechanical system including the roller and the dynamometer was accelerated to a rated speed with the dynamometer in a state where the test vehicle was not placed on the roller. After that, the coasting operation with the absorption torque of the dynamometer set to zero is performed, and the mechanical loss on the front wheel side and the rear wheel side for each vehicle speed section is obtained by measuring the elapsed time for each vehicle speed section during this coasting operation, and the test is performed. From the measured value of the running resistance value when the vehicle coasts on the road, the running resistance value of the rolling resistance and the air resistance for each vehicle speed section is obtained by the least squares method.
Each running resistance value was corrected as a value under standard environmental conditions, and the air resistance component of the corrected running resistance value was distributed from the center of gravity of the test vehicle to the front wheels and the rear wheels, and was distributed with the mechanical loss. The air resistance value and the inertial component are set as traveling resistance loads of the front wheels and the rear wheels for each vehicle speed section.

Further, according to the present invention, the coasting time of the test vehicle is measured by the set value of the running resistance load, the absorption torque of the dynamometer is calculated from the measured data, and the distribution ratio is calculated by the absorption torque value. It is characterized by performing a learning operation that is reset.

[0018]

[Operation] By calculating the mechanical loss of the chassis dynamometer having various dynamometer combinations for each vehicle speed section by the coasting operation of the mechanical system, the mechanical loss corresponding to the traveling resistance can be obtained for the chassis dynamometer of any structure. Make it easy.

The rolling resistance and the air resistance are calculated from the running resistance measurement values by coasting on the test course, and the running resistance value of the automobile is accurately obtained by correcting the rolling resistance and the air resistance to the standard environmental conditions.

By distributing the obtained air resistance of the running resistance to the front wheels and the rear wheels from the center of gravity of the automobile, a value close to the actual distribution of the running resistance of the front wheels and the rear wheels of the actual vehicle is obtained.

Further, the accuracy of setting the traveling resistance load is increased by performing the learning operation so that the error from the coasting time measurement value by the traveling resistance setting and the standard value data on the test course falls within the allowable value.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a block diagram of an apparatus showing an embodiment of the present invention. In the figure, the control device 6 shows only the traveling resistance control block.

The mechanical system is provided with pulse pickups 11F and 11R for vehicle speed detection and torque meters 12F and 12R for torque detection, as in the conventional case. The torque meters 12F and 12R obtain feedback signals to the torque control units 13F and 13R for running resistance control.

The pulse pickups 11F, 11R obtain the vehicle speed detection signals for obtaining the running resistance as a function of speed, and also the front and rear wheels 1F, 1R and the dynamometer 3F,
Synchronous rotation control unit 1 for synchronously rotating 3R and the like
The rotation angle detection signal of 4 is obtained.

The mechanical loss correction units 15F and 15R are rollers 2
F, 2R, flywheels 4F, 4R and dynamometers 3F, 3R have mechanical loss as a function of speed,
This correction value is given to the torque control units 13F and 13R as correction torque.

The running resistance load setting unit 16 obtains a running resistance that is a function of speed from the speed detection signal. The running resistance adjusting / distributing unit 17 adjusts the running resistance obtained by the setting unit 16, distributes the running resistance according to the ratio of the torque loaded by the front and rear wheel dynamometers 3F, 3R, and the torque control units 13F, 13F.
Get the torque setpoint for R.

The coasting time measuring unit 18 obtains the mechanical loss by measuring the coasting time from the speed detection signal and the elapsed time when the mechanical system is coasted.

The operation of setting the traveling resistance load will be described below.

(1) Measurement of mechanical loss of chassis dynamometer.

There are various combinations of drive methods for chassis dynamometers as described above. However, it is possible to reproducibly correct running resistance load by measuring the mechanical loss corresponding to the rotation speed of the chassis dynamometer equipment. Required.

For measuring the mechanical loss, the dynamometer 3F, the test vehicle 1 without the rollers 2F, 2R was used.
The 3R is accelerated to the rated speed in the speed control mode, and when the speed detection becomes stable, the dynamometers 3F and 3R are switched to the torque control mode, and the zero torque command is given to the torque control unit 13.
Set to F, 13R.

From the start of coasting by the zero torque, the coasting time measuring section 18 is provided with pulse pickups 11F, 11
The rotation speed from R and the elapsed time are measured respectively.

The measured changes in speed and time are as shown in FIG. 2, and the coasting time to reach each speed P ₁ , P ₂ , P ₃ , P ₄ , ... Is measured in each speed section, The loss of the mechanical system is calculated from this measured value. This calculation formula is as follows.

[0034]

[Equation 2]

However, M _L ; mechanical loss (N) ΔV; speed change width (Km / h) Δt; time required for speed change (seconds) W; mass of rotating parts such as rollers (Kg) coasting time measuring part 18 The mechanical loss on the front wheel side and the mechanical loss on the rear wheel side, which are obtained in step S4, are set in the mechanical loss correcting units 15F and 15R as speed-mechanical loss characteristics, respectively.

(2) Measurement of running resistance of the test vehicle 1.

The test vehicle 1 is coasted from a constant vehicle speed on a road such as a test course, and the running resistance is obtained by the coasting method of measuring the coasting time for each vehicle speed section as in the case of FIG. Set to 16.

The running resistance at this time is obtained from the following equation.

[0039]

[Equation 3]

However, R _L ; running resistance (N) W ₀ ; empty vehicle mass (Kg) K ₄ ; rotational inertia coefficient of the rotating part W _M ; weight of the occupant at the time of measurement (Kg) ΔV; speed change Width (Km / h) Δt; Time required for speed change (second) Running resistance R for each vehicle speed section obtained from the above equation (2)
For _L1 to R _Ln, determined as the following equation as the speed relationship in the least squares method.

[0041]

[Formula 4] F = a + bV ² (3) However, F: Running resistance (excluding inertia and gradient) a: Value corresponding to rolling resistance (N) b: Corresponding to air resistance coefficient Value (N / (Km / h) ² ) V; Velocity (Km / h) Next, the values a and b obtained from the equation (3) are corrected as the values under the standard environmental conditions. That is, in coasting time measurement on the test course, the influence of temperature, humidity, wind speed, etc. of the test course on the measurement accuracy is corrected and corrected to standard value data.

The values a and b are corrected according to the following equation.

[0043]

[Formula 5] F ₀ = a ₀ + b ₀ V ² ‥‥‥‥‥‥‥‥‥ (4-1) a ₀ = (a-bv ² ) (1 + 0.00864 (T-20)) ・ ・ ・ ・ ・ ・ ・ ・ (4-2) b ₀ = 345.8 · b (T + 273) / P (4-3) where F ₀ ; standard running resistance (N) v; average wind speed (Km / h) a ₀ at the time of test on test course a ₀ ; Rolling resistance in standard state (N) b ₀ ; Air resistance coefficient in standard state T; Average temperature during test on test course (° C) P; Average atmospheric pressure during test on test course (hPa) Travel determined by the above formula By setting the resistance F ₀ in the load setting unit 16 as data for each vehicle speed section, it is possible to obtain a standard running resistance in the test in which the influence of temperature, humidity, etc. of the test course is removed.

(3) Distribution of running resistance.

In the equation (4-1), the rolling resistance a ₀ of the first term is equally divided into the front and rear wheels, but the air resistance b ₀ V ² of the second term is different from that of the front wheel depending on the position of the center of gravity of the automobile. The load on the rear wheels changes. This will be described below.

FIG. 3 shows the load on the front and rear wheels depending on the position of the center of gravity of the automobile. The air resistance b ₀ V ² of the equation (4-1) is set to _Fa
The load W _{F of the} front wheel 1F is calculated by the following equation from the relationship between the force exerted by the air resistance _Fa on the vehicle 1 and the vehicle center of gravity position CG.

[0047]

[Equation 6]

Where L is the dimension between the wheel bases (m) L ₁ is the dimension of the center of gravity and the front wheels (m) L _{2 is} the dimension of the center of gravity and the rear wheels (m) h _c is the height of the center of gravity (m ) h _a; when determining the vehicle weight (Kg) the front wheel load W _F as the ratio of the body weight W _0,; center height consuming air resistance (m) W ₀
The equation (5) is obtained as the following equation (6).

[0049]

[Equation 7]

From the front wheel load ratio W _F / W _{0 in the} above equation (6), the vehicle body weight ratio W _R / W ₀ of the rear wheel load W _R can be obtained from the following equation.

[0051]

From Equation 8] _{W R / W 0 = 1-} W F / W 0 ‥‥‥‥‥ (7) that up to above the load bearing of the front and rear wheels by the air resistance F _a and (6) ( 7), and the running resistance adjusting / distributing unit 17 calculates the air resistance F _a of the running resistance from the running resistance load setting unit 16 by (6),
The distribution is made according to the distribution ratio of equation (7).

Incidentally, the simplified formula of the distribution ratio can be L ₂ / L in which the _second and third terms of the equation (6) are omitted.

(4) Adjustment of running resistance.

After the distribution setting is made, the deviation between the running resistance in the actual running and the set value of the running resistance load in the chassis dynamometer is corrected.

For this correction, a coasting test on the bench of the test vehicle 1 is carried out according to the running resistance setting set as the distribution,
At this time, the absorption torque of the dynamometer is calculated from the measurement data of the coasting time measurement unit 18, the distribution setting of the distribution unit 17 is redone with this absorption torque value, and the test and reset are performed until the error falls within the allowable value. Repeat learning driving.

The relationship between the absorption torque and the set running resistance can be obtained based on the following equation.

[0057]

[Equation 9]

However, F _c : running resistance value ε determined from the coasting time on the chassis dynamometer ε; allowable error range F _c ′; dynamometer absorption torque (N) F _c-1 ′; previous dynamometer absorption Torque (N) F ₀ ; 1st running resistance set value α; constant The learning operation ends when the inequality of the above equation (9) is satisfied, and the target running resistance and the load distribution ratio of the front and rear wheels that match the actual vehicle. Run the test with the running resistance load set in.

The embodiment is not limited to the setting of the running resistance load of a four-wheeled vehicle, but it goes without saying that it can be used for setting the running resistance load of an FF vehicle or an FR vehicle.

When the inertia component is set to the electric inertia component, the torque component is added to the running resistance setting.

[0061]

As described above, according to the present invention, the mechanical loss of the mechanical system of the chassis dynamometer is obtained on the front wheel side and the rear wheel side by coasting operation, and from the running resistance measurement value of the test vehicle on the road. Calculate the rolling resistance and air resistance, correct them as values under standard environmental conditions, distribute the air resistance from the center of gravity of the automobile to the front and rear wheels, and calculate the mechanical loss and the distributed air resistance and inertia. Since it was set as the running resistance load together, the setting that matches the running resistance in actual running, especially the distribution of the front wheels and the rear wheels to the difference in the drive system of the test vehicle and the configuration of the chassis dynamometer It is possible and the running resistance load can be easily measured.

Further, since the learning for adjusting the set value of the running resistance load to the standard data during the actual running from the coasting operation is performed, the running resistance load can be set with high accuracy.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a coasting time measurement waveform diagram.

FIG. 3 is a diagram for explaining a load applied to an automobile.

FIG. 4 is a configuration diagram of a chassis dynamometer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Test vehicle, 2F, 2R ... Roller, 3F, 3R ... Dynamometer, 4F, 4R ... Flywheel, 6 ... Control device, 13F, 13R ... Torque control part, 14 ... Synchronous rotation control unit, 15F, 15R ... Mechanical loss correction unit, 16
… Running resistance load setting unit, 17… Running resistance adjustment / distribution unit,
18 ... Coasting time measuring section.

Claims (2)

[Claims] 1. A chassis for conducting a simulated running test by connecting a pair of dynamometers to the front and rear wheels of a test vehicle through rollers respectively, and setting the running resistance of the vehicle to the absorption torque of the dynamometer. In the dynamometer, the roller under test is not mounted on the roller,
After accelerating the mechanical system including the dynamometer to the rated speed with the dynamometer, the coasting operation is performed with the absorption torque of the dynamometer being zero, and the elapsed time is measured for each vehicle speed section during this coasting operation for each vehicle speed section. The mechanical resistance of the front wheel side and the rear wheel side is calculated, and the rolling resistance and the air resistance equivalent to the air resistance for each vehicle speed section by the least square method from the measured value of the running resistance value when the test vehicle is coasted on the road. The value is obtained, and each running resistance value is corrected as a value under standard environmental conditions, and the air resistance of the corrected running resistance value is distributed from the center of gravity of the test vehicle to the front wheels and the rear wheels, A method of setting a traveling resistance load, characterized in that the loss and the distributed air resistance value and inertia are set as traveling resistance loads of front wheels and rear wheels for each vehicle speed section. 2. The coasting time of the vehicle under test is measured according to the set value of the running resistance load, the absorption torque of the dynamometer is calculated from this measurement data, and the distribution ratio is reset with this absorption torque value. The driving resistance load setting method according to claim 1, wherein learning operation is performed.