JPH0339632A - Controller for chassis dynamometer - Google Patents

Abstract

PURPOSE:To simulate the travel state of a vehicle on a low-friction road by providing setters which set a friction coefficient mu and vehicle equivalent inertia W, a computing element which calculates the product muW, and a comparator which compares the product muW with travel resistance. CONSTITUTION:The computing element 102 calculates the product muW of the set value W of the vehicle equivalent inertia setter 14 and the set value mu of the friction coefficient setter 101. An adder 103 adds the rotational resistance value Fmu of a tire obtained from the calculation result and a travel resistance value Fp outputted from a travel resistance setter 12 according to a vehicle speed electric signal from an amplifier 8 and the comparator 104 compares the addition result. When travel resistance R/L generated on a drum 2 by the dynamometer 3 becomes larger than muW, a relay 105 turns on according to the comparison result to switch the input of the adder 11 from the resistance value Fp to the resistance value Fmu and the input of a multiplier 13 from the set value W to the set value Ws of an equivalent inertia setter 106 at the time of tire idling. Consequently, the resistance R/L generated on the drum 2 becomes the resistance value Fmu. Further, an inertia-compensated inertia quantity varies from the set value W to the equivalent inertia Ws.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for a chassis dynamometer, and more particularly to a control device for a chassis dynamometer suitable for simulating the running condition of a vehicle on a low-friction road.

[Conventional technology]

In a conventional chassis dynamometer, for example, as shown in FIG. 3, a drum 2 corresponds to the road surface with respect to a vehicle 1, and the drum 2 is directly connected to a dynamometer 3.

The dynamometer 3 is operated by automatic torque control with the configuration described below.

That is, a thyristor, a torque control device 5, a load cell 6 that detects the torque reaction force generated by the dynamometer 3, and an electric signal from the load cell 6 is sent to the dynamometer 3 via an amplifier 7 as a torque feed pack signal. Output.

Further, the rotation of the dynamometer 3 is detected by a rotation detector 9, which is converted into a vehicle speed electrical signal by an amplifier 8, and the vehicle speed electrical signal is output to a running resistance setting device 12 and a differentiator 15.

The running resistance setter 12 sets the running resistance collected in advance while driving on the actual road, and outputs a running resistance value command corresponding to the vehicle speed value from the amplifier 8 to the adder 11. On the other hand, the differentiator 15 calculates a speed change rate based on the vehicle speed value from the amplifier 8 and outputs it to the multiplier 13. Multiplier 13
The speed change rate from the differentiator 15 is multiplied by the set value W from the vehicle equivalent setting device 14 to calculate the inertial torque. These are called electrical inertia compensations.

The inertia torque calculated in this way is calculated by the adder 11
The adder 11 adds it to the running resistance value command and outputs it to the adder lO. The adder IO automatically controls the torque of the dynamometer 3 by comparing the running resistance value command with the torque feedback signal from the amplifier 7. That is, the dynamometer 3 is operated so as to generate the running resistance value set by the running resistance setting device 12.

Related devices of this type include, for example, Meidensha Jiho 1976 Nu 6 (Tsundou No. 149), pages 19 to 26, and regarding electrical inertia compensation,
For example, Japanese Patent Publication No. 56-101531 can be mentioned.

[Problem to be solved by the invention]

The above-mentioned conventional technology enables simulation only when the vehicle is running steadily and when accelerating and decelerating, as described above.

However, there is a problem in that it is not possible to simulate conditions in which slip occurs between the vehicle tires and the road surface due to a decrease in the coefficient of friction μ, that is, driving conditions on roads with a low coefficient of friction (for example, snowy roads, frozen roads, etc.). .

SUMMARY OF THE INVENTION An object of the present invention is to provide a chassis dynamometer control device that is capable of simulating the running state of a vehicle on a low-friction road in addition to simulating steady running and acceleration of a vehicle.

[Means to solve the problem]

When a vehicle enters a low-friction road and slips, the slipping tires spin and accelerate without moving the vehicle forward. Vehicle operation on low-friction roads must simulate this condition.

The conditions for tires to slip on a low-friction road are μ・W<R/L (1) where μ is the coefficient of friction between the tires and the road surface, W is the vehicle weight, and R/L is This is running resistance.

That is, when the vehicle enters a low-friction road, μW becomes small, and when it becomes smaller than the running resistance R/L at that time, the tires start slipping.

It is also clear that a slipping tire will not move the vehicle forward, so the tire will spin, and the rotational resistance Fμ of the tire will be μW. Therefore, the running resistance R/L can be considered to be μW.6 Also, the inertia force applied to the slipping tire is only the drive system of the vehicle (tires, engine power system), and this amount of inertia is assumed to be Ws.

Therefore, in order to achieve the above object, the chassis dynamometer control device of the present invention includes a friction coefficient setting device for setting the friction coefficient μ, a vehicle equivalent inertia setting device for setting the vehicle equivalent inertia W, and a friction coefficient setting device for setting the friction coefficient μ, a vehicle equivalent inertia setting device for setting the vehicle equivalent inertia W, and A calculator that calculates the product μW of the coefficient μ and the vehicle equivalent inertia W, and the product μ calculated by the calculator
A comparator that compares W and the running resistance R/L, and when compared by the comparator, the product μW and the running resistance R/L.
S is the condition for tires to spin on a low-friction road, that is, μW<
The vehicle is equipped with a switch that switches the running resistance R/S to the product μW calculated by the calculator and the equivalent inertia W of the vehicle to the equivalent inertia Ws when the tires are spinning when R/L is reached.

[Effect]

In the present invention, in order to simulate a low-friction road condition from a steady running condition, first, a friction coefficient μ is set using a friction coefficient setting device.
The setting of is decreased to satisfy the condition μW<R/L.

Under these conditions, the running resistance is switched from R/L to μW, and the electric inertia compensation inertia is switched from W to Ws using a switch. Before entering a low-friction road, the forward force of the vehicle is equal to the running resistance R/L at that time, and if the opening force of the vehicle is kept constant (accelerator depression amount is constant), the running resistance R/L andμ
The difference in force from W causes the slipping tire to spin and accelerate.

Further, the inertia applied to the tire becomes V su ws (v: vehicle speed) due to electric inertia compensation, so the tire will spin due to sudden acceleration.

The above conditions are physically identical to the low-friction road conditions on the actual road, and a low-friction road simulation can be performed on a chassis dynamometer.

〔Example〕

Hereinafter, a description will be given of FIG. 1, which shows a low friction road control device for a chassis dynamometer, which is an embodiment of the present invention.

In FIG. 1, the parts that are different from the conventional FIG. A computing unit 102 is provided to compute the product μW (hereinafter referred to as Fμ).

In addition, a vehicle equivalent inertia amount setter 106 sets the equivalent inertia Ws when the tires are spinning on a low-friction road, and an addition that adds the output Fμ of the arithmetic unit 102 and the running resistance command value FP that is the output of the running resistance setting unit 12. A comparator 104 for determining the result of addition by the adder 103 is provided.

Furthermore, a relay 105 is provided which operates based on the comparison result of the comparator 104. The relay 105 is the adder 1
1 is input to the running resistance value FP to the output Fμ of the arithmetic unit 102 and the vehicle equivalent inertia W input to the arithmetic unit 13.
is switched to the equivalent inertia Ws when the tire is spinning.

Since the parts other than the above are the same as those in FIG. 3, they are indicated by the same reference numerals as in FIG. 3.

Next, the operation will be explained.

Setting value W of vehicle equivalent inertia setting device 14 and friction coefficient setting device 1
The product μW with the friction coefficient set value μ of 01 is calculated by the calculator 102, and the rotational resistance value Fμ of the tire obtained as a result is calculated.
An adder 103 adds the running resistance value FP output from the running resistance setter 12 based on the vehicle speed electrical signal from the amplifier 8, and compares the addition result with a comparator 104.

Then, based on the comparison result by the comparator 104, relay 1
05 switches the running resistance value F inputted into the adder 11, the rotational resistance value Fμ of the tire, the set value W inputted by the vehicle equivalent inertia setting device 14 inputted into the multiplier 13, and the inertia amount Ws.

In this case, the vehicle 1 starts slipping on a low-friction road because
The condition of the above formula (1), that is, the tire rotational resistance value Fμ(
=μW) is smaller than running resistance R/L.

This detection is performed by comparing the rotational resistance value Fμ of the tire with the running resistance value FP using the adder 103 and the comparator 104 as described above.

The running resistance value FP is the output of the running resistance setting device 12 as described above. As also mentioned above, since automatic torque control is configured by the output F of the running resistance setting device 12 and the torque feedback signal of the load cell 6 of the dynamometer 3, the running resistance generated on the drum 2 by the dynamometer 3 is R/L has a relationship of R/L=FP. Therefore, the above formula (
It can be detected under the condition 1).

When the relay 105 is ON, the input of the adder 11 is changed from the running resistance value FP to the rotational resistance value Fμ of the tire, and the input of the multiplier 13 is changed from the value W set by the vehicle equivalent inertia setting device 14 to the equivalent inertia Ws when the tire is spinning. Switch.

As a result, the running resistance R/L generated in the drum 2 becomes the rotational resistance value Fμ of the tire. Further, the inertia compensation inertia amount becomes the equivalent inertia Ws when the tire is spinning from the set value W of the vehicle equivalent inertia setting device 14.

Next, it will be explained with reference to FIG. 2 whether the low friction road condition can be controlled by the above operation.

In FIG. 2, it is assumed that the vehicle 1 is traveling at a constant speed vl. In this state, if the rolling force of the vehicle 1 is Fu, then Fu=R/L ("Fp) --(2) R/
The relationship is L<Fμ.

In order to bring the vehicle l into a low-friction road state from the above state, the setting of the friction coefficient μ is decreased in accordance with the friction coefficient μ of the low-friction road to be simulated. As a result, if R/L>Fμ, the relay 105 is turned ON and operates as explained above, and the running resistance R/L and tire rotational resistance value F shown in FIG.
The difference from μ is the torque that accelerates the slipping tire. Furthermore, since the inertia V has been switched to Ws, the electric inertia compensation of dtWs is activated, and the inertia applied to the tires is only the equivalent inertia Ws when the tires are spinning, resulting in rapid acceleration.

If the driving force Fu of vehicle 1 remains unchanged, that is, if the accelerator pedal is left unchanged, the tires will spin due to vehicle 1.
As the engine speed increases, the driving force Fu of the vehicle 1 increases.
The vehicle speed v2 decreases and matches the tire rotational resistance value Fμ.
increase to.

Also, if you press the accelerator again midway through the process, the upper limit rotational speed of the tire will increase. If the accelerator is released midway, the idling rotational speed becomes constant before the vehicle speed reaches v2. And the acceleration torque of the idle tire at this time is F, -Fμ,
Determined by the value of friction coefficient μ. It is also clear that the rotational resistance of the tire during tire slip is only Fμ.

A simulation of the vehicle 1 on a low-friction road is performed as described above.

Next, to recover from the low-friction road, the set value of the friction coefficient μ may be increased to restore the condition of Fμ>R/L.

In addition, in the above embodiment, 2WD (two-wheel drive vehicle)
Although the chassis dynamometer described above is not limited to this, it can be applied to a 4WD (four-wheel drive vehicle) by installing two sets of the configuration shown in FIG. 1, for example. Furthermore, in a chassis dynamometer for a 4WD vehicle in which independent drums are provided for each of the four wheels, the configuration shown in FIG. 1 can also be applied by providing four sets. Furthermore, when the four-wheel metal part or any wheel among the four wheels is brought into a low-friction road state, the setting of the friction coefficient μ corresponding to that wheel can be reduced.

〔Effect of the invention〕

Analysis of vehicle driving conditions on low-friction roads is an important issue in the advancement and improvement of vehicle handling stability.
According to the present invention, it is possible to perform a low-friction road simulation equivalent to an actual road on a chassis dynamometer, which can greatly contribute to the above-mentioned analysis.

Additionally, demand for 4WD vehicles has been increasing in recent years. It is said that the steady running performance of 4WD vehicles is significantly superior to that of 2WD vehicles. However, when the tires slip on a low-friction road, not only does this advantage disappear, but a 4WD vehicle loses the cooperative power of all four wheels if one of its four wheels slips, so it is at a disadvantage compared to a 2WD vehicle on a low-friction road. becomes.

Therefore, in the case of 4WD vehicles, differential gear devices that control differential gearing are being actively developed.

Low-friction road simulation using a chassis dynamometer is essential for these developments and product tests.

According to the present invention, these low-friction road simulations are possible, and the effect of meeting the above needs is very large.

[Brief explanation of drawings]

FIG. 1 is a functional system diagram showing a low-friction road control device for a chassis dynamometer that is an embodiment of the present invention, and FIG. 2 is a diagram showing the relationship between vehicle speed, vehicle driving force, and running resistance. FIG. 3 is a functional diagram of a conventional chassis dynamometer. 1...Vehicle, 2...Drum, 3...Dynamometer, 4...
... Thyristor, 5... Torque control device, 6... Load cell, 7.8... Amplifier, 9... Rotation detector,
10.11...Adder, 12...Running resistance setter,
13... Arithmetic unit, 14... Vehicle equivalent inertia setting device, 1
5... Differentiator, 101... Friction coefficient setter, 102
... Arithmetic unit, 103 ... Adder, 104 ... Comparator, 105 ... Relay, 106 ... Equivalent inertial device setting device when the tire is spinning.

Claims (1)

[Claims] 1. An automatic torque control device that provides a running resistance R/L to a dynamometer, a running resistance setter that provides a running resistance command value to the automatic torque control device, and an acceleration resistance corresponding to the equivalent inertia W of the vehicle to the dynamometer. In the chassis dynamometer, the chassis dynamometer is equipped with an electric inertia compensator for setting the friction coefficient μ between the tires of the vehicle and the road surface, and a tire slipping equivalent inertia setting device for setting the equivalent inertia W_s when the tires are slipping. a calculator for calculating the product μW of the friction coefficient μ and the equivalent inertia W of the vehicle; and the product μW calculated by the calculator;
A comparator that compares the running resistance R/L, and when the product μW and the running resistance R/S reach the condition that the tire spins on a low friction road, that is, μW<R/L when compared by the comparator. , a switch for switching the running resistance R/S to the product μW calculated by the calculator and the equivalent inertia W of the vehicle to the equivalent inertia W_s when the tires are spinning, and is configured to enable simulation on a low-friction road. A control device for a palm dynamometer.