JPS5825217B2 - Electric dynamometer torque measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a torque measuring method for an electric dynamometer, and in particular, by adding an acceleration signal of rocker inertia as a correction amount to an actual torque detection signal, measurement can be performed at a very high response speed. Furthermore, the present invention aims to provide a new torque measurement method in which only the true amount of torque is extracted, without including vibration components and oscillator displacement errors that may cause control errors in the corrected torque measurement signal. be.

In general, a vortex-type or DC-type electric dynamometer has a schematic structure as shown in FIG.

That is, a load cell 5 made up of a combination of strain gauges is disposed between the torque arm 4 and the bed 2 to which the rocker 1 is fixed, and a desired torque signal is extracted from the load cell 5.

In the same figure, numeral 3 indicates a bearing stand that supports the rocker 1.

In the electric dynamometer configured in this way, the actual torque detection signal generated by the dynamometer and taken out from the load cell 5 is used, as is well known, when performing torque control or running resistance control on the dynamometer, or when controlling the amount of torque. This type of actual torque detection signal is used when giving instructions with an indicating instrument, and the torque measurement system shown in Figure 2 shows how this kind of actual torque detection signal was conventionally obtained. In this case, for example, the actual torque detection signal taken out from the load cell 5 is first converted into a voltage signal by the strain converter 6, this voltage signal is once amplified by the amplifier 7, and this amplified signal is used for torque control. Predetermined torque control, running resistance control, etc. are performed via the circuit 8.

In Fig. 2, 9 is an indicator that indicates the actual torque amount, and 1
0 is an output terminal for recording torque.

The problems with the detection system configured in this way are, firstly, that the actual torque cannot be detected at a very high response speed, and secondly, the actual torque detection signal contains a vibration component, resulting in high accuracy. Moreover, coordinated control cannot be performed.

To explain the reason specifically, the oscillator shown in Figure 1 has a fairly large inertia, and the load cell has a spring constant of a certain magnitude because it vibrates due to the force applied to both ends. This spring constant also changes depending on the support structure of the load cell, such as the cushion mount (rubber) and the rigidity of the torque arm, so due to these factors, the torque generated by the dynamometer may be transient due to the inertia of the oscillator. Not only is the torque not accurately transmitted to the load cell, but the spring constant of the load cell and the inertia of the oscillator generate vibrations, and this vibration component is included in the load cell output.

The present invention was invented in view of this point, and is particularly characterized in that the acceleration of the rocker inertia is detected and this acceleration detection signal is added to the actual torque detection signal as a torque correction amount. This will be explained in detail based on the principle diagram shown in FIG.

The mutual relationship between the force applied to the load cell and the extracted fruit shown in FIG. 1 is roughly expressed as shown in FIG. 3.

In the figure, F is the torque generated by the dynamometer converted into the force at the tip of the torque arm, and this force F is applied to both ends of the load cell.

Similarly, W is the inertia of the oscillator converted into mass point weight at the tip of the torque arm (load cell application point), and this oscillator inertia W is also applied to both ends of the load cell.

Fl is the force applied to the load cell. Based on these factors, the spring constant of the load cell is K, the torque generated by the dynamometer is T, the moment of inertia of the oscillator is J, and the force from the tip of the torque arm to the axis of the dynamometer is When the distance is assumed to be X, and the equivalent displacement of the oscillator is assumed to be X, the above F, Fl, and W can be expressed as follows.

That is, F = T/L...■, F1=Kx...
・・・■、W=J/L2・・・・・・■ Top = Based on the conditions of D formula, 0 formula, and ■ formula, calculate the difference between the force actually applied to the load cell and the torque generated by the dynamometer. has the following relationship.

T/L 10Wd2X/dt2-Kx-0・・・・・・・・・
......... Substituting the above formula 0 and formula ■ into formula ■01, we get TZL+J/L2・d"x/d t2-F1
=0 ・・・・・・・・・■T/L-F1-J/L2・
d2x/dt2......It is determined as shown in the formula 00, and this formula 0 can be modified to be expressed as shown in the following formula for determining the dynamometer generated torque T.

That is, T-(Fl-J/L2・d2x/dt”)XL・
......■ As is clear from this formula 0, the generated torque T of the dynamometer is 1/2πiAW〒It vibrates especially during transients, and this vibration frequency is usually 5 to 20Hz, ζlower frequency. be.

As described above, such fluctuations in the load cell output become a major hindrance when measuring transient torque waveforms or when it is desired to make the response speed of torque control extremely fast.

Therefore, in the present invention, focusing on the fact that the torque generated by the dynamometer can be expressed as the above equation 0, we first measure the acceleration at the tip of the torque arm as shown in FIG.
If it is given as a correction amount to the actual torque detection signal, even if the actual torque detection signal contains a unique vibration frequency,
Since the signal that detects the acceleration of the inertia of the oscillator from the actual torque detection signal taken out from the load cell is quickly input to the torque control system or running resistance control system, this acceleration detection signal is first used to control the specified acceleration. Torque control or running resistance control is performed, and then the actual torque detection signal taken out from the load cell is input to the control system, so after that, the true difference between this actual torque detection signal and the acceleration detection signal of rocker inertia is determined. Predetermined control is performed using the torque detection signal.

To describe this specifically, when the above equation 0 is transformed, the following equation is obtained.

In other words, the torque generated by the dynamometer is T=F'L J/L-d2x
/dt2......■ In this formula 0, the term F'L on the right side is the actual torque detection signal directly detected by the load cell, while the term J/L-d2x/d t'' is the detected acceleration of the oscillator inertia, and as is clear from this equation 0, the true amount of torque generated by the dynamometer is the detected amount of acceleration of the oscillator inertia than the actual torque taken out from the load cell. It is understood that the value obtained by subtracting the product of the rocker inertia is the true amount of torque.

In addition, the torque correction amount added in the term on the right side of the above equation 0 is −(
The reason for this is that when the direction (polarity) of the X coordinate is treated as positive polarity in Figure 3, and on the contrary, when the direction of the X coordinate is treated as negative polarity, the torque is added to the actual torque detection signal. The amount of correction will be added.

Therefore, in the present invention, focusing on this point, first the amount of acceleration of the rocker inertia is detected, and this detected amount of acceleration is added as a torque correction amount to the actual torque detection signal, so that the true value generated by the dynamometer can be adjusted. By determining the torque amount of , first performing predetermined control using the torque correction amount, and then performing predetermined control using the true torque amount of this torque correction amount and the actual torque detection signal, This enables highly coordinated torque measurement or control.

As is clear from the above explanation, by detecting the acceleration of the rocker inertia and inputting this detected acceleration amount as the torque correction amount, it is possible to measure and record the actual torque amount with a very high response speed, and it is also possible to Although responsive torque control or running resistance control is possible, even with these methods, the actual torque detection signal extracted from the load cell still has two types of signals, one caused by mechanical vibration and the other caused by power supply. Since there is a possibility that a pulsating component due to voltage fluctuations is included, control may become unstable due to this pulsating component.

Therefore, in the present invention, such high frequency pulsating components are removed by using a low pass filter such as an active filter to achieve the desired purpose.

Note that if an integral element such as a filter is inserted into the torque measurement system, it can be said that this integral element causes a delay in control, making it impossible to perform coordinated control. Since the signal that detects the acceleration of the mover inertia is input as the torque correction amount, the torque correction amount is input to the control system before the actual torque detection signal taken out from the load cell, and this torque correction A predetermined control is performed based on the amount, and then a predetermined control is performed using the true torque amount of the actual torque detection signal and the torque correction amount, so torque control is highly coordinated. Alternatively, it is possible to control running resistance, etc.

FIG. 4 is a concrete block configuration diagram of a measurement system showing an embodiment of the present invention. In the figure, the same reference numerals as in FIG. 1 have almost the same functions, and the explanation thereof will be omitted. 11 is an acceleration detection circuit that detects the acceleration of the inertia of the rocker, and 12 is an acceleration conversion circuit that converts the acceleration detection signal into a voltage signal.

13 is a coefficient circuit for adding a predetermined coefficient (oscillator inertia) to the acceleration detection signal.

14 is a filter circuit that removes high frequency pulsation components of the mechanical system from the actual torque detection signal taken out from the load cell 5;
15 is a comparison circuit that compares the actual torque detection signal and the acceleration detection signal of the rocker inertia.

As described above, in the present invention, the true torque amount is measured by adding the signal that detects the acceleration of the rocker inertia as the torque correction amount to the actual torque detection signal taken out from the load cell. Therefore, various effects can be achieved as shown below.

- Vibration (pulsation) caused by the inertia of the oscillator and the spring constant of the load cell can be reliably suppressed, making it possible to measure torque and record torque waveforms in a coordinated manner.

(2) When performing predetermined torque control, running resistance control, etc. for the reason in item 0 above, highly accurate and highly coordinated control becomes possible.

- Since the signal that detects the acceleration of the rocker inertia can be simply inputted as the torque correction amount, torque measurement is very simple and an economical device can be realized.

[Brief explanation of the drawing]

Figure 1 shows a specific configuration example of a typical electric dynamometer, Figure 2 is a principle diagram showing the interaction between the torque generated by the power system according to the present invention and the force actually applied to the load cell, and Figure 3. The figure is a specific block configuration diagram showing a conventional torque measurement system.
The figure is a block configuration diagram showing an embodiment according to the present invention. 1 is an oscillator, 4 is a torque arm, 5 is a load cell, 6 is a strain converter, γ is an amplifier, 8 is a control circuit, 11 is an acceleration detection circuit, 12 is an acceleration conversion circuit, 13 is a coefficient circuit, and 14 is a filter , 15 is a comparison circuit.

Claims (1)

[Claims] 1. A torque arm is fixed to the oscillator, a load cell is installed between the torque arm and the dynamometer support, and the drive-absorbed torque of the dynamometer taken out from the load cell is measured. In such a device, the acceleration of the inertia of the oscillator is detected, this acceleration detection signal is multiplied by the inertia of the oscillator to obtain a torque correction signal, and this torque correction signal is taken out from the load cell. A torque measuring method for an electric dynamometer, characterized in that only true torque is measured by adding (subtracting) to an actual torque detection signal. 2. A torque arm is fixed to the oscillator, a load cell is installed between the torque arm and the dynamometer support base, and the amount of torque generated by the dynamometer taken out from the load cell is measured. The actual torque detection signal is extracted directly from the load cell. Once input to the filter circuit, this filter circuit removes only the pulsation component unique to the mechanical system included in the actual torque detection signal, and the oscillator inertia is added to the actual torque detection signal from which this pulsation component has been removed. A torque measuring method for an electric dynamometer, characterized in that only the true torque amount is measured by adding the product of the detected acceleration amount and the inertia of the oscillator as a torque correction amount. 3. As a device for detecting the acceleration of rocker inertia, there is an acceleration detection circuit that detects the amount of acceleration of inertia, an acceleration conversion circuit that converts the acceleration signal output from this circuit into a voltage signal, and a voltage signal output from this circuit. A torque measuring method for an electric dynamometer according to claim 1 or 2, comprising a coefficient circuit that adds rocker inertia to an acceleration signal to obtain an acceleration amount.