JP2001091411A - Front-rear axle load controlling method in four-wheel drive vehicle bench test - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve control accuracy for a front-rear axle load distribution ratio in a 4WD vehicle bench test. SOLUTION: A pulse generator PP is arranged in each tire 9 in a vehicle on a bench test base, a tire speed is detected by means of a speed detection unit 24, a mean speed in each axle is found in a computing unit 12, a front-rear axle mean speed is found in the computing unit 12, a traveling resistance command is formed in a traveling resistance command generation unit 11 on the basis of the mean speed, and torque control units 21 on the front and rear wheel sides control a power meter 4 for traveling resistance control so as to eliminate torque deviation. A difference between mean speeds of the front and rear axles is found in a computing unit 14, and on the basis of the difference speed, an electric command synchronizing the power meters 4 on the front and rear axle sides is formed for converting a command polarity to the rear wheel side current control unit 22 by means of a converter 15, and consequently, a dynamometer 2 is controlled by means of current control units 22 on the front and rear wheel sides. Because a tire speed is used instead of a roller speed for traveling resistance control and synchronous control, control accuracy of a front- rear axle load distribution ratio can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a longitudinal axis load control method for a chassis dynamometer for testing a four-wheel drive vehicle.

[0002]

2. Description of the Related Art The following types of four-wheel drive (4WD) vehicle 4WD systems are available. 1) Part-time 4WD: A device that selectively switches between four-wheel drive and two-wheel drive (two front wheels or two rear wheels).

[0003] In 4WD, the distribution of driving force before and after is proportional to the dynamic load distribution. 2) Full-time 4WD: The vehicle always travels at 4WD, and is divided as follows according to the driving force distribution method to the front and rear axes.

[0004] Constant distribution ratio method A method in which the distribution ratio is changed according to the rotational speed difference between the front and rear shafts.

[0005] A system in which the distribution ratio is changed by electronic control according to the running state or road surface condition. 3) Passive 4WD: When there is no rotation difference between the front and rear wheels of the vehicle, the vehicle runs at 2WD, and when a difference in rotation occurs, it is 4WD.

FIG. 4 shows a mechanical configuration diagram of a chassis dynamometer for testing a 4WD drive vehicle. The front and rear shafts of this test device are mechanically independent and are connected via the front and rear wheels of the vehicle. Although FIG. 4 shows only the left side of the vehicle and omits the right side, there is actually a right tire and a roller for receiving the tire, and the right roller is connected to the left roller.

Next, FIGS. 5 and 6 show examples of this control system diagram. This control system includes dynamometers 2 _F and 2 _R on the test device side in FIG.
And the flywheels 3 _F and 3 _{R control the} 4WD vehicle 8 to apply a load equivalent to that when the vehicle actually travels on the road (running resistance control). That is, the steady running resistance is absorbed by the dynamometer, and the acceleration / deceleration running resistance is absorbed by the flywheel. In the actual case, a mechanical loss compensating circuit, an electric inertia control, and the like are often attached in addition to the above, but they are omitted because they are not related to the essence of the present invention.

The control system shown in FIG. 5 is for a full-time 4WD vehicle of the above-mentioned constant distribution ratio type. Since the front and rear distribution ratio of the driving force on the vehicle side is constant (1/2), the dynamometers 2 _F and 2F on the front and rear shafts are used. load absorption of 2 _R also the running resistance of the entire vehicle to share a constant ratio (1/2), the running resistance command generating unit 11
The running resistance command from the motor is supplied to the ratio setting device 18 and the adder 19.
Are torque control as the running resistance command of the constant ratio (1/2) as the torque control section 21 _F and 21 _R by.

The running resistance command generator 11 includes a speed detector 24
_F, 24 generates a running resistance command based from the speed detection value of _R before and after the average speed obtained before and after the average vehicle speed calculating unit 12.

The control system of FIG. 6 corresponds to a 4WD vehicle in which the driving force distribution ratio on the vehicle side changes during driving, and the running resistance of the vehicle is determined by two dynamometers 2 _F and 2 _R. The distribution is such that the speed difference between the front and rear rollers 1 _F and 1 _R is equal to the front-rear axis speed difference when traveling on the road. It becomes zero.
This is because the distribution of driving force when traveling on a vehicle road is greatly affected by the rotational speed difference between the front and rear vehicles, and if this is reproduced on the chassis dynamometer, the distribution of driving force of the vehicle will eventually be reproduced. Can be.

In FIG. 6, the torque control units 21 _F and 21 _R are provided with a command from the running resistance command generation unit 11 and a torque detection unit 2.
The deviation from the sum of the torque detection obtained by adding the torque detection from 3 _F and 23 _R by the adder 16 is calculated by PI. Differential speed calculator 1
4 calculates the difference between the speed detections from the speed detectors 24 _F and 24 _R , and the front-rear synchronization control unit 13 inverts the current command of the front-rear synchronization control according to the speed difference and this signal by the polarity reversing circuit 15. The driving command distribution is reproduced by adding the current command to the current command output from the torque control units 21 _F and 21 _R.

[0012]

In the case of a vehicle in which the driving force distribution on the vehicle side changes during driving, this ratio changes in accordance with the driving condition of the vehicle. Is a major factor, and is allocated to make this a zero. On the other hand, in order to cope with this in the conventional FIG. 6, attention is paid to a roller speed (two dynamometer speeds) that is simple for speed detection, and control is performed so that the speed is the same, but a spring is provided between the roller and the tire. Yes, this size varies depending on driving force and tire conditions. For this reason, even if the roller speed is adjusted, a speed difference remains between the tires, and as a result, the vehicle may be operated at a ratio different from the distribution on the road surface.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to control longitudinal load control in a four-wheel drive chassis test that can improve the control accuracy of the longitudinal load distribution ratio. It is to provide a method.

[0014]

The front-rear axis load control system in the four-wheel drive chassis test according to the present invention comprises a front left and right roller and a rear left and right roller driven by front and rear wheels of a vehicle, respectively. In a four-wheel-drive undercarriage test that combines the dynamometer for the front axle and the rear axle and the flywheel, and controls both dynamometers in synchronization with the running resistance control, each tire speed of the vehicle is detected, and the left and right front wheels are detected. An average speed and a differential speed of the front-rear axis are calculated from each tire speed and the tire speeds of the right and left rear wheels, a running resistance control command is generated based on the average speed, and a current command of the front-rear axis synchronization control is generated based on the difference speed. And the running resistance of both dynamometers is controlled so that the deviation between the running resistance control command and the average torque detection of both dynamometers is eliminated, and synchronization is performed so that the speed difference between both shafts is eliminated. By different polarities of the control of the current command, characterized in that the current control.

[0015] Instead of detecting the tire speeds described above, measurement data of the shaft speed of an electronic control unit that distributes and controls the driving force of the engine mounted on the vehicle to the front and rear axes is read out via an interface. The average speed and the difference speed between the front axis and the rear axis can be calculated using the measured data of the axis speed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment FIG. 1 shows a control system for running resistance and synchronization control of a four-wheel drive chassis test apparatus according to a first embodiment. The front wheel side of this control system,
The rear wheel side control circuits 20 _F and 20 _R have the same configuration.
The control circuit 20 _F (20 _R ) is provided with speed detecting pulse detectors PP ₁ and PP ₂ on the left and right tires 9 ₁ and 9 ₂ of the front wheels (rear wheels), and the speed detectors 24 ₁ and 24 ₂ detect the pulses from the pulses. The left and right tire speeds are calculated, and the average value of the left and right tire speeds is obtained by the speed average value calculation unit 25. As for the torque of the dynamometer 2, the pressure applied to the load cell is detected by the load cell LC provided in the dynamometer, and the torque is calculated by the torque detection unit 23.

The front-rear average speed calculation unit 12 includes a control circuit 2
The average of the average speeds from the speed average value calculation unit 25 of 0 _F and 20 _R is calculated to calculate the average speed of all tires, and the running resistance command generation unit 11 generates a running resistance command based on the average speed of all tires. I do.

The differential speed detecting section 14 includes control circuits 20 _F and 20 _R
Of the average speed from the speed average value calculation unit 25 of
The front-rear synchronization control unit 13 outputs a current command for front-rear synchronization control according to the difference in the average speed.

The torque control unit 21 of the control circuits 20 _F and 20 _R
Calculates the difference between the running resistance command from the running resistance command generating section 11 and the value obtained by adding the torque detection from the torque detecting section 23 of the control circuits 20 _F and 20 _R by the adder 16 by PI.

The current control unit 22 of the control circuit 20 _F controls the dynamometer 2 the sum of the current command from the current command and a longitudinal synchronization control unit 13 from the torque control unit 21 as a current command. The current control unit 22 of the control circuit 20 _R is
The dynamometer 2 is controlled using the sum of the current command from the controller and the current command from the front-rear synchronization controller 13 as the current command for the front-rear synchronization control whose polarity has been changed by the polarity reversing circuit 15.

In the first embodiment, the tire speed of the vehicle is detected, and the average speed of the detected tire in the front-rear axis is calculated.
Since the running resistance command is obtained from the front-rear axis average speed and the dynamometers of the front and rear wheels are synchronously controlled to eliminate the torque deviation and the current deviation, the driving force distribution of the front-rear axis can be correctly reproduced.

Embodiment 2 A 4WD vehicle is equipped with an electronic control unit (ECU) for controlling the distribution of the engine driving force to the front and rear axes. ECU
In order to obtain data for the above-mentioned distribution control, sensors are attached to each part to measure various data. In the second embodiment, in the front-rear axis load control of the four-wheel drive chassis test on which the ECU is mounted, the same front-rear axis load control as in the first embodiment is performed using the front-rear axis left and right speed data measured by the ECU. Things.

Embodiment 2 will be described with reference to FIGS. 2 and 3. FIG. 2, the ECU 30 includes a CPU 31, a measurement interface 32, a memory 33, and a test interface 34. Each signal from each of the sensors S is input to the measurement interface 32 and the CPU
The processing is sequentially performed at 31 and temporarily stored in a memory provided in the memory 33 and the test interface 34. On the other hand, the dynamometer measuring device A is configured as shown in FIG. 1 as shown in FIG. 3, but the pulse detectors PP ₁ and PP ₂ are not attached to the 4WD vehicle to be tested. The control circuit is constituted by a CPU except for the output unit of the current control unit 22 that drives the dynamometer 2.

The CPU of the power measuring device A is based on the EC
The test interface 34 of the ECU 30 is used to perform longitudinal axis load control using the measurement data measured by the U30 and temporarily stored in the memory of the interface 34.
Connect with

Next, the operation of the second embodiment will be described.
The interface 34 of the ECU 30 outputs a measurement interrupt signal to the dynamometer control device A every time the sequentially measured data becomes available. The dynamometer control device A requests measurement data from the interface 34 of the ECU 30 every time the measurement interrupt signal is input, obtains measurement data from the interface 34, and obtains the rotation speed of the front shaft left and right and the rear shaft left and right rotation speed data. If the front wheel side 20 _F and the rear wheel side 20 by calculating the average value the average speed of the front and rear axes respectively in the calculating portion 25 of the _R: Figure 1 of FIG. 3 as well as to control longitudinal axis synchronously with.

According to the second embodiment, it is not necessary to consider the difference between the measured values existing between the ECU mounted on the vehicle and the chassis dynamometer. In addition, since the control of the chassis dynamometer can be performed simultaneously with the driving force distribution control on the ECU side, the control can be performed faster than in the case of performing the correcting operation after the rotation speed difference occurs in the tire of the first embodiment. Become. In addition, the ECU interface has higher reliability than the detection of the tire rotation speed.

[0027]

Since the present invention is configured as described above, the following effects can be obtained. (1) By directly measuring and controlling the tire speed,
Eliminate the effect of slip between the roller and tire,
The longitudinal axis speed of the vehicle can be accurately controlled. This improves the control accuracy of the front-rear shaft load distribution ratio. (2) When the measurement values of the ECU that distributes the driving force of the vehicle are used, it is not necessary to consider the difference between the measurement values existing between the ECU and the test device. (3) In addition, the control of the test apparatus can be performed simultaneously with the driving force distribution control on the ECU side, and the control for performing the correcting operation after the rotation speed difference occurs in the tire is quickened. (4) Also, the measurement data of the shaft speed of the ECU interface is more reliable than the detection of the tire rotation speed, the operation is simple, and the cost is advantageous.

[Brief description of the drawings]

FIG. 1 is a dynamometer control block diagram according to a first embodiment.

FIG. 2 is a schematic configuration diagram of a measurement data exchange portion when the dynamometer control device according to the second embodiment uses measurement data of an ECU.

FIG. 3 is a power control block diagram according to a second embodiment.

FIG. 4 is a schematic configuration diagram of a chassis dynamometer for a 4WD test.

FIG. 5 is a block diagram of a constant-ratio running resistance control according to a conventional example.

FIG. 6 is a block diagram of a running resistance / synchronous control according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Roller of a test apparatus 2 ... Load absorbing dynamometer 3 ... Mechanical flywheel 4 ... Load absorbing dynamometer 9 ... Tire 11 ... Running resistance command generation part 12 ... Front-back average speed calculation part 13 ... Front-back synchronization control part 14 ... Differential speed calculation unit 21. Torque control unit 22. Current control unit 23. Torque detection unit 24. Speed detection unit 25. Speed average value calculation unit.

Claims (2)

[Claims] 1. A dynamometer and a flywheel for a front shaft and a rear shaft are respectively coupled to left and right rollers for a front wheel and left and right rollers for a rear wheel driven by front and rear wheels of a vehicle, respectively.
In a four-wheel drive chassis test in which both dynamometers are controlled synchronously with running resistance control, each tire speed of the vehicle is detected, and the average speed of the front and rear axes and Calculate the differential speed, generate a running resistance control command based on this average speed, and generate a current command for front-rear axis synchronization control based on the difference speed, and calculate the running resistance control command and the average torque of both dynamometers. The dynamometer is controlled by running resistance so as to eliminate the deviation, and the current is controlled by changing the polarity of the current command of the synchronous control so that the speed difference between the two axes is eliminated. Front-rear axis load control method in test. 2. A dynamometer and a flywheel for a front shaft and a rear shaft are respectively connected to left and right rollers for a front wheel and left and right rollers for a rear wheel driven by front and rear wheels of a vehicle,
In a four-wheel drive chassis test in which both dynamometers are controlled synchronously with running resistance control, shaft speed measurement data of an electronic control unit that distributes and controls the engine driving force mounted on the vehicle to the front and rear axes is used as an interface. The average speed and the differential speed of the front axis and the rear axis are calculated using the measured data of the axis speed, a running resistance control command is generated based on the average speed, and the longitudinal axis is calculated based on the differential speed. Generates a current command for synchronous control, controls the running resistance of both dynamometers so that there is no deviation between the running resistance control command and the average torque detection of both dynamometers, and performs synchronous control so that there is no speed difference between both shafts. A front-rear axis load control method in a four-wheel drive chassis test, wherein current control is performed by changing the polarity of the current command.