JPS6221029A - Phase difference type torque detector - Google Patents

Abstract

PURPOSE:To enable highly accurate detection of torque, by controlling the reference voltage for conversion of a square wave so that the duty ratio of a signal contracts to 50%. CONSTITUTION:Sensors 1-3 detect the positions of teeth of gears 4-6 to gener ate detection signals S1, S2 and S3. Signal processing circuits 10 and 11 process the signals S1 and S2 from the sensors 1 and 2 in the same way. Here, first, the output signal P1 of a waveform shaping circuit 12, the signal PN1 and the signal P1 obtained through an AND circuit 14 and a counter 17 and the signal PN2 obtained through a 1/2 frequency dividing circuit 13 and a counter 18 are taken into a microcomputer 23 separately. The microcomputer 23 calculates the data (t) (pulse width during the period of the positive half cycle of the signal P1) and the data T (the pulse width during the cycle period of the signal P1), outputs a 3 bits of control data DVR based on the results to be inputted into a selection circuit 1 of a reference voltage setting circuit 19 and the threshold voltage of the circuit 12 varies accordingly. Then, the micro computer 23 calculates the duty ratio D of the signal P1 to change the control data DVR so that the D=50%.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a device for detecting torque transmitted through a drive shaft of a vehicle such as an automobile, and in particular a device that operates without contact using a rotational position detection sensor. The present invention relates to a torque detection device.

[Background of the invention]

As the demand for more sophisticated and multi-equipment control of vehicles such as automobiles increases, various detection devices are being used, and one of these detection devices is a torque detection device. .

As a torque detection device for such a vehicle,
Although detection methods based on various detection principles have been proposed in the past, the current situation is that none with sufficient practicality is known.

There are many reasons that hinder the practical application of such torque detection devices, but one of the most important reasons is that the signal from the torque detection section is temperature dependent. This is due to variations due to changes over time and variations in the characteristics of the detection unit.

For example, Japanese Patent Application Laid-open No. 49-57880 discloses a torque detection device capable of detecting static torque, but it also mentions the gain and zero dip correction for the torque detection signal. , there is no mention of consideration of variations in the characteristics of the torque detection section, temperature dependence, aging, etc. mentioned above.

Therefore, it is difficult to improve the accuracy of conventional torque detection devices, particularly those that detect torque as a phase difference signal, and this has been a bottleneck for practical use.

[Purpose of the Invention] The present invention was made with the background of superiors, and is capable of sufficiently and easily compensating for the effects of variations in the characteristics of the torque detection section, temperature dependence, and changes over time. The purpose of the present invention is to provide a positional differential torque detection device that can always perform torque detection with high accuracy and is highly practical.

[Summary of the invention]

In order to achieve this object, the present invention detects the duty ratio of this rectangular wave signal in a method in which a rotational position detection signal is converted into a rectangular wave signal (pulse signal) and then detects a phase difference. It is characterized in that the reference voltage for rectangular wave conversion is controlled so as to converge to %.

[Embodiments of the invention]

Hereinafter, regarding the phase difference t-torque detection device according to the present invention,
This will be explained in detail with reference to the illustrated embodiment.

FIG. 1 shows an embodiment of the present invention, in which 1 to 3 are sensors for detecting rotational position, 4 to 6 are magnetic gears, 7 is a rotating shaft, and 10 and 11 are signal processing circuits. , 12.22 is a waveform shaping circuit, 13 is a 1/2 frequency divider, 14.15 is an AND circuit, 16 is a clock generation circuit, 17.18 is a counter,
19 is a reference voltage setting circuit, 20 is a voltage generation circuit, 21 is an achievement circuit, and 23 is a microcomputer (microcomputer).

Sensors 1-3 are magnetic resistance type position detectors, and gears 4-6
The position of each tooth is detected, and each detection signal Sl
, 82, 83.

Here, if you are wondering about the principle of torque detection using the phase difference method, the rotating shaft 7 is a rabbit. The gears 4 and 5 are provided on the rotating shaft 7 at a predetermined distance l. Therefore, when power is transmitted by the rotating shaft 7, twisting occurs in the rotating shaft 7 depending on the torque at that time, and a deviation in the rotational direction occurs between the gears 4 and 5.
As a result, a phase difference proportional to the torque appears between the signals S1 and 82 of sensors 1 and 2. Therefore, torque can be detected by measuring the phase difference between these signals S1 and 82, and this is the principle of phase difference type torque detection. The sensor 3 is for generating a timing signal S3 for signal processing, and has only one tooth, and is coupled to a gear 6, which is mounted as close as possible to the gear 4. 7 rotates once and reaches a predetermined rotation angle (one predetermined angle change among 360 #), a signal S3 is generated.

The signal processing circuit 10 processes the signal S1 from the sensor 1,
Similarly, 11 processes the signal S2, and since they are the same, the waveform shaping circuit 12 mainly processes 10, and the waveform shaping circuit 12 is a comparison circuit such as an operational amplifier. It functions to shape the signal S1 using the reference voltage given from the reference voltage circuit 19 as a threshold voltage and convert it into a rectangular wave signal P1.

Therefore, the relationship between these signals S1 and Pl is as shown in diagram F3. Similarly, the signal 82 from the sensor 2 is also converted into a rectangular wave signal P2 by the waveform V-shaped circuit IC in the signal processing circuit 11. Then, since τ in the signal representing the phase difference between these signals Pi and P2 becomes a signal representing torque τ, the microcomputer 23 takes in these signals Pi and P2, calculates the pulse width of τ in the signal, and calculates the torque. It stands as if calculating.

By the way, now suppose that the average value of the signal S2 from the sensor 2 increases by ΔV due to temperature changes, as shown in the signal P2' in Figure 3. On the other hand, the threshold voltage of the waveform shaping circuit changes to vRl. Therefore, the rectangular wave signal at this time becomes P2', and its positive pulse width also changes from 1+ to t.

As a result, even though there was no change in the torque to be measured, the signal representing the phase difference between signals P1 and P2 at this time had changed from τ to τ', and the detected torque value had changed. It will be difficult to do so.

Therefore, in this embodiment, as shown in FIG. 1, the output signal P1 of the waveform shaping circuit 12 is first applied to the AND circuit 14, which gates the clock CL output from the clock generation circuit 16 to generate a clock pulse train. PS1 is obtained, supplied to the counter 17 for counting, and the resulting PNI is taken into the microcomputer 23.

On the other hand, this signal P1 is
/2 frequency divider circuit 13 to obtain the frequency divided signal Pi2, and this signal P12 is input to the AND circuit 15 to gate the clock CL, thereby obtaining the clock pulse train PS.
2 is supplied to the counter 18 for counting, and the count result PN2 is taken into the microcomputer 23.

Now, if the period of the clock CL is δt, as is clear from FIG. 3, (PNixat) represents the pulse width t of the positive half cycle period of the signal P1, and similarly, (PN
2Xδt) represents the width T of one cycle period of the signal P1. That is, it becomes.

And since this is the same for the signal processing circuit 11,
Even if the signal P2 is .degree. C., t and T can be obtained, respectively.

Therefore, the microcomputer 23 stores these data t.

Calculate T and based on it, 3-bit control data DV
and based on it, f! The A voltage setting circuit is input to the selection circuit 21 of the fin 19.

This basic fishing torpedo pressure setting time #19 is based on 3-bit control data D.
The f selection circuit 2I controlled by vR and one of eight different positive pressures depending on the output of this selection circuit 21 are set as the reference positive pressure ■
It consists of a voltage generating circuit 20 that outputs as .

Therefore, when the microcomputer 23 outputs predetermined control data DvR, the threshold voltage of the waveform shaping circuit [12] changes accordingly, and the average level is controlled for converting the signals S1 and S2 into rectangular wave signals P1 and P2. can be done.

Therefore, the microcomputer 23 generates the stiff data t.

Based on TK, the duty ratio D of signals PI and P2 (D =
t/'l' x 100%), and as a result, D
The control data DVR will be transformed so that =50% can be obtained. For example, as shown in 9r L above, the signal S2 in Figure 3 changes to S2' due to temperature changes, and as a result, the signal P
2 becomes like P 2', the control data DV
By changing R, the output of the reference voltage setting circuit 19 is raised from vRl to vR2 by a positive voltage ΔV. Then, the width t of the signal P2' returns to tl again like the signal P2, and the signal τ' representing the torque also returns to its original value τ, making it possible to detect the correct torque.

Next, an embodiment of the processing of the microcomputer 23 necessary for the operation on the U will be described with reference to the flowcharts shown in FIG. 4 and FIG.

FIG. 4 shows the main processing routine 50. First, in step 51 (hereinafter referred to as step S), input/output ports of the microcomputer 23 are set.

In S52, the interrupt flag IRQFLG is checked and the interrupt processing (
Figure 5) Waiting state.

If the result at 852 becomes Y (YES), reset the interrupt flag at 353, and set the sensor flag to 5EN at continuation <854.
SORFLG is checked and it is decided whether to perform processing by the signal processing circuit 10 of sensor 1 or by signal processing circuit 11 of sensor 2, and in the case of sensor 1, S
If it is sensor 2, go to 356. In addition, 5EN
If SORFLG -1, sensor 1. Sha5ORFLG
= O, sensor 2 is selected.

Since the processing contents are the same in S55 and 856, in S57 and 861, the duty ratio is calculated from the time t and TK taken in from the processing circuit 10 or 11 of Sonezawa. .

D-(t/'r)xloo(%) ・・・・・・・・・
...(2) The duty ratio is 5 for S58 and 362
It is determined whether or not it is within 0% of 0%.

When the result is Y, reverse 859 and 863 and S5
At 9, the sensor flag is set to O, and at 863, the sensor flag is set to 1.

When the results at 858 and 862 are N (No), they turn to 860 and 864, respectively, and set the value of the low-value lightning pressure vR by the base sIF pressure setting circuit 19 to (D-50).
Move up or down by one step depending on the sign of . In other words,(
When D-50) is a square, it means that the duty ratio is less than 50%, so lower the threshold voltage VR by one step, and conversely, if (D-50)7')"- becomes positive, the threshold voltage This means raising the pressure V by one step.

Thereafter, the process returns to step S52 and waits for the next interrupt to occur.

Next, FIG. F5 shows an interrupt process 70, which starts at the rising edge of the signal P3 obtained by waveform shaping the signal S3 from the sensor 3 in FIG. 1, and first sets the interrupt flag IRQFLG to 1 in S71.

In the following S72, the sensor flag 5FNSORFLG is read to determine which of the sensor 1 and sensor 2 signal processing is to be performed. If the flag is 1, the signal processing circuit 1
0 signal processing is performed in 873, and if the flag is 0, signal processing in the signal processing circuit 11 is performed in 874.

The processing contents of S73 and S74 are the same in other respects except that the signal to be taken in is sent to either of the signal processing circuits 10 and 11, so the explanation will be made using -g.

First, 875.881 generates a signal RESET in order to reset the counter 17.18.

Next, at 376.882, the process fx waits for the end of time t. For this purpose, for example, it is sufficient to check the falling edge of the signal P1.

If the result in S76 and S82 is Y, 877°883
Read the count result and find the time t.

At step 878 and S84, the process waits for the measurement of time T to end. For this purpose, for example, it is sufficient to check the y-downstream of the signal P12.

And 879. In S85, the count result is read and time T is determined.

Note that, due to the characteristics of the microcomputer 23, there is a delay of Δt from when the signal P3 shown in FIG. 3 appears until the *4F2+ process shown in FIG. 5 starts. Therefore, the teeth of gear 6 must be positioned in a predetermined positional relationship with respect to the teeth of gear 4.

Therefore, according to the above embodiment, even if the average value of the signals Sl and S2 changes due to changes in temperature, aging, or variations in the characteristics of the sensors 1 and 2, the rectangular wave signal P
Since the duty ratios of I and P2 are always corrected to 50% α, torque can always be detected accurately.

In the above embodiment, magnetoresistive position detectors are used as the sensors 1 to 3, but optical position detectors may be used instead.

In addition, in the above embodiment, the hardware components 17 and 18 are used to measure the times t and T, but instead of these, a soft counter machine based on the program of the microcomputer 23 is used. Good too.

-T operation of the interrupt processing routine at this time is shown in Figure F6.

In this embodiment, first, S86. The time t is measured in S89, then the time (T-t) is measured in 887 and 890, and finally the time T is calculated in S88 and S91.

Therefore, according to this embodiment, the hardware configuration can be simplified.

〔Effect of the invention〕

As explained above, according to the present invention, even if a fluctuation occurs in the average value of the sensor signal, a correction is made that does not affect the tuning of the rectangular wave signal for phase difference detection. Because it is carried out, it eliminates the drawbacks of conventional technology and can be applied to vehicles such as automobiles to maintain accuracy and high reliability even under the influence of changes in temperature, aging, and variations in element characteristics. A phase difference type torque detection device capable of detecting torque can be easily provided.

[Brief explanation of the drawing]

Figure 11E+ is a block diagram showing one embodiment of the phase difference torque detection device according to the present invention, Figure 2 is a detailed explanatory diagram of the sensor portion, Figure 3 is a time chart for explaining the operation, and Figure 4
Figures 2 and 2-5 are 70-charts for falsifying operations, and the terrorist diagram is a flowchart explaining the operation of another example #2. 1-3... Sensor for rotational position detection, 4-6.
... Magnetic gear, 7 ... Rotating shaft to which the torque to be measured is transmitted, 10.11 ... Flaw processing circuit, 12.22 ... Waveform Shaping circuit, 13...
...1/2 frequency divider, 14,15...AND circuit, 16...clock generation circuit, 17,18...
... Counter, 19 ... Base fp'wt pressure setting circuit, 20 ... Voltage generation circuit, 21 ...
・Edge selection circuit, 23...Microcomputer. Figure 2 and Figure 3! :I Figure 4 Figure 5 Figure 6

Claims (2)

[Claims] 1. A waveform shaping circuit outputs first and second rectangular wave signals by inputting rotational position signals detected on the torque input side and the torque output side of a torque transmission shaft having a predetermined rigidity, respectively. A phase difference type torque detection device that detects torque based on a phase difference between rectangular wave signals includes a measuring means for detecting a duty ratio of the rectangular wave signals, and a measuring means for detecting a duty ratio of the rectangular wave signals, and a measuring means for detecting a duty ratio of the rectangular wave signals. and a threshold voltage setting means for controlling the threshold voltage of the waveform shaping circuit, and the phase difference type torque detection is configured such that the duty ratio of the rectangular wave signal is controlled to converge to a predetermined constant value. Device. 2. In claim 1, the measuring means comprises:
The counter includes a counter that counts the clock signal during one polarity portion of the rectangular wave signal, and a counter that counts the clock signal over the entire one cycle period of the rectangular wave signal. A phase difference type torque detection device, characterized in that it is configured to detect a duty ratio of the rectangular wave signal based on a ratio of counting results of a counter.