JPH07128192A - Torque detection method for chassis dynamometer - Google Patents

Abstract

PURPOSE:To provide a torque detection method for a chassis dynamometer which enables the detection of a torque generated simply without providing a torque sensor. CONSTITUTION:In a chassis dynamometer which is connected mechanically to a roller 1 on which a drive wheel 2 of a test vehicle is placed and a motor 3, acceleration is determined from the speed of the motor 3 when the coasting operation of the drive wheel 2 is made while no torque is generated from the motor 3. On the other hand, acceleration is determined from the speed of the motor 3 when the coasting operation of the drive wheel 2 is made while a torque is generated from the motor 3. Thus, a torque generated is detected based on both the acceleration and a mechanical inertia value of the roller 1, the motor 3 and a rotating part of the vehicle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque detecting method in a chassis dynamometer.

[0002]

2. Description of the Related Art In a conventional chassis dynamometer, as shown in FIG. 7, a drive wheel 11 of a test vehicle is placed and a motor 13 for braking a roller 12 for absorbing power of the test vehicle operates in accordance with a torque command. In order to detect whether torque is generated, a torque sensor 15 is provided on a shaft 14 that mechanically connects the roller 12 and the motor 13, and the torque sensor 15 measures the generated torque. In this figure, 16 issues a torque command to the motor 13 and receives detection outputs from a speed sensor (not shown) provided on the motor 13 or the shaft 14 and a torque sensor 15 to control the entire apparatus. It is a control device that operates.

[0003]

However, in the above method, the torque sensor 15 is indispensable, the number of constituent members is increased accordingly, and the torque sensor 15 is considerably expensive, which increases the cost of the chassis dynamometer. Was there.

The present invention has been made in consideration of the above matters, and provides a torque detecting method (hereinafter simply referred to as a torque detecting method) in a chassis dynamometer capable of easily detecting a generated torque without providing a torque sensor. It is intended to be provided.

[0005]

In order to achieve the above object, the present invention is a chassis dynamometer in which a motor on which a drive wheel of a test vehicle is placed and a motor are mechanically connected to each other, the motor generating torque. The acceleration is obtained from the speed of the motor when the drive wheel is coasting in the state where the torque is not generated, and the acceleration is obtained from the speed of the motor when the drive wheel is coasting while the motor is generating torque. The characteristic feature is that the generated torque is detected based on both accelerations and the mechanical inertia amounts of the roller, the motor, and the vehicle rotating portion.

[0006]

According to the torque detecting method having the above-mentioned structure, the generated torque can be easily obtained only by coasting the driving wheel on the roller, and it is not necessary to provide an expensive torque sensor.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 schematically shows an example of the construction of an apparatus for carrying out the torque detecting method according to the present invention. In FIG. A roller 3 for absorbing the power is mechanically connected to the roller 1 through a shaft 4, for example, an eddy current type motor 5, a torque command a is issued to the motor 3, and a motor 3 or a shaft 4 is provided. It is a control arithmetic unit that receives a detection output b from a speed sensor (not shown) provided and controls the entire device that performs an arithmetic operation based on various inputs.

Next, the procedure for obtaining the torque generated by the motor 3 using the above apparatus will be described with reference to FIGS. First, the drive wheels 2 are run on the rollers 1 so that torque is not generated in the motor 3 (that is, the torque command voltage is 0 V), the gear of the test vehicle is set in the neutral state, and the coasting operation (also referred to as coast down) is performed. I do. The relationship between the speed v of the motor 3 and the time t at this time is represented by, for example, a vt graph as shown in FIG.

[0009] In FIG. 2, (in the figure, shown by a dotted line) tangent at a certain time because the slope of represents acceleration dv ₁ / dt of the motor at that time, to the acceleration dv ₁ / dt, roller 1 The frictional force F (v) at that time is obtained by multiplying the motor 3 and the mechanical inertia amount I of the vehicle rotating portion. That is, F (v) = I × dv ₁ / dt ...

Next, in the state where the torque command voltage a is applied to the motor 3 to generate the torque in the motor 3, the drive wheels 2 are coasted in the same manner as above. At this time, the relationship between the speed v of the motor 3 and the time t is v-as shown in FIG.
It is represented by a t-graph.

In FIG. 3, the inclination of the tangent line (indicated by the dotted line in the figure) at a certain point represents the acceleration dv ₂ / dt of the motor at that point. And
In this case, the product of the acceleration dv ₂ / dt and the mechanical inertia amount I is the sum of the roller surface force f (v) by the motor 3 and the frictional force F (v). That is, f (v) + F (v) = I × dv ₂ / dt ...

From the above equation, f (v) = I × (dv ₂ / dt-dv ₁ / dt) ...

That is, it can be seen that the roller surface force f (v) by the motor 3 at the speed v of the motor 3 is obtained by multiplying the difference in inclination of the tangent lines in FIGS. 3 and 2 by the mechanical inertia amount I.

In this way, the drive wheels 2 with and without the torque command voltage applied to the motor 3.
The roller surface force f (v) of the motor 3 can be calculated based on the velocity and acceleration of the coasting operation of No. 1 and the mechanical inertia amount I which is known in advance.
Therefore, unlike the conventional method, it is possible to easily confirm whether or not the motor 3 generates the torque according to the torque command voltage, without using the torque sensor.

By the way, FIG. 4 shows a plot of the frictional force at each speed v in FIG. 2, that is, the motor 3
Represents the relationship between the speed and the frictional force of the
And the vertical axis represents the frictional force F. Also, FIG.
Is a plot of the roller surface force at each speed v in FIG. 3, that is, the relationship between the speed of the motor 3 and the surface force of the roller 1 generated by the motor 3, and the horizontal axis represents the speed. v is taken and the vertical axis is the surface force f.

By using the data shown in FIGS. 4 and 5, the driving force T output by the test vehicle at a certain point in time when the drive wheels 2 of the test vehicle are driven can be obtained. Now, it is assumed that v-t at the time of driving is as shown in FIG. That is, in this figure, a curve A represented by a solid line shows a running pattern of the test vehicle on the roller 1.

The inclination of the tangent line (indicated by the solid line in the figure) at a certain time point A in such a running pattern represents the acceleration dv ₃ / dt of the drive wheel 2 at that time point. _{Therefore, I × dv 3 / dt =} T-F (v) -f (v) a .....

From the above equation, T = I × dv ₃ / dt + F (v) + f (v) ...

[0019]

As described above, according to the present invention, unlike the conventional method, the generated torque can be easily detected without using the torque sensor. Therefore,
The structure of the chassis dynamometer is simplified and the cost is reduced. Further, it is not necessary to lift up the test vehicle when coasting the drive wheels.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing the configuration of an apparatus for carrying out the method of the present invention.

FIG. 2 is a graph showing an example of the relationship between the speed of the motor and the time when the coasting operation is performed while the motor is not generating torque.

FIG. 3 is a graph showing an example of the relationship between the speed of the motor and the time when the coasting operation is performed while the motor is generating torque.

FIG. 4 is a graph showing an example of the relationship between motor speed and frictional force.

FIG. 5 is a graph showing an example of the relationship between the motor speed and the roller surface force generated by the motor.

FIG. 6 is a diagram showing an example of a traveling pattern.

FIG. 7 is a diagram for explaining a conventional method.

[Explanation of symbols]

 1 ... roller, 2 ... drive wheel, 3 ... motor.

Claims (1)

[Claims] 1. A chassis dynamometer in which a motor on which a drive wheel of a test vehicle is placed and a motor are mechanically connected is used. The acceleration is obtained from the speed, and the acceleration is obtained from the speed of the motor when the drive wheel coasts while the torque is being generated by the motor. A method for detecting torque in a chassis dynamometer, characterized in that the generated torque is detected based on