JPH04104023A - Torque detecting apparatus - Google Patents

Abstract

PURPOSE:To detect the accurate torque by obtaining the phase difference based on the position signals of two magnetic recording layers on a rotary shaft, obtaining the number of rotations of the rotary shaft, and operating the torque generated in the rotary shaft. CONSTITUTION:Magnetic recording layers 11 and 12 are formed on the outer surface of a rotary shaft 10 with a specified distance L being provided. Specified magnetic patterns are recorded and reproduced with magnetic heads 13 and 14. Magnetic signals are generated in a recording circuit 15 and imparted into the heads 13 and 14. The reproduced signals of the magnetic patterns which are reproduced in the heads 13 and 14 are inputted into a phase-difference detecting circuit 19. In the circuit 19, the phase difference between the reproduced signals is detected. The difference is imparted into a torque operating circuit 20. Meanwhile, a number-of-rotation detector 32 generates a signal indicating the number of rotations N of the rotary shaft 10. The signal is imparted to the torque operating circuit 20. In this way, the phase difference and the number of rotations are imparted into the circuit 20, and the torque T which is applied on the rotary shaft 10 is operated and outputted.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a torque detection device for a rotary shaft that is rotationally driven, and particularly to an in-vehicle device that detects the torque of a rotary shaft such as an automatic transmission of an automobile from the amount of torsion of the shaft. The present invention relates to a torque detection device for use in a vehicle.

[Conventional technology]

In recent years, the need for torque detection in automobiles has been increasing. In particular, it is expected that the characteristics of automatic transmissions using torque converters will be greatly improved by detecting the torque of the output shaft.

Furthermore, in a four-wheel drive vehicle, it is very important to detect the torque distribution between the front and rear wheels.

As a device for detecting the torque of such a rotating shaft, there is a device that measures the twist angle of the rotating shaft caused by the torque load.
Devices that calculate torque from this torsion angle by calculation have been widely known.

Generally, two rotary encoders are placed on the rotating shaft to be measured, separated by a predetermined distance in the axial direction, and the torsion angle is determined from the phase difference between the output signals from both encoders. Calculating torque. Rotary encoders generally use optical means or magnetic means. For example, JP-A-62
Japanese Patent No. 239031 discloses an example using a rotary encoder using a magnetoresistive element.

[Problem to be solved by the invention]

However, the torque detection device using the above-mentioned rotary encoder has a problem in that highly accurate torque detection cannot be performed. The first factor is an unavoidable installation error when attaching a rotary encoder to a rotating shaft. If there is an error in such a mounting, a phase difference will occur between the two rotary encoders even when there is no load. And the second factor is
This is the change over time of the rotating shaft itself. That is, torsional strain remains on the rotating shaft over time, and this causes an error in the phase difference between the two rotary encoders.

In order to solve such problems, Japanese Patent Application No. 1-2545
No. 61 discloses a novel torque detection device. In this device, two magnetic recording media are provided at a predetermined distance from a rotating shaft. And when there is no load, these two
Periodic signals of the same phase are written on two magnetic recording media. When detecting torque under load, this periodic signal is read out and the phase difference is detected to determine the torsion angle, and the torque is calculated from this torsion angle. With such reproduction, it is possible to rewrite the periodic signal at any time, so that accurate measurements can be made without errors due to time errors or changes over time. However, there are still problems with this device that need to be resolved. The point is that it is necessary to write periodic signals on the magnetic recording medium. The numerical value of the frequency of the periodic signal will be used to calculate the torque, but if the period of the written periodic signal fluctuates, it will not be possible to define the exact frequency, and the value obtained as a result of the calculation will be The torque value will include an error. In general, the rotational speed of a rotating shaft of a vehicle drive system frequently fluctuates, so it is difficult to accurately write a signal with a constant period to a magnetic recording medium provided on this rotating shaft. Therefore, the written periodic signal does not accurately become a periodic signal with a predetermined pitch, and the torque value ends up containing an error.

SUMMARY OF THE INVENTION An object of the present invention is to provide a torque detection device that is suitable for downsizing and that can accurately detect torque even on a rotating shaft whose rotational speed varies.

[Means to solve the problem]

The present invention includes two magnetic recording media formed at a predetermined distance from each other in the circumferential direction of a rotating shaft, two magnetic heads for recording and reproducing predetermined position signals on and from the two magnetic recording media, and the two magnetic heads. A recording means for performing recording by applying a position signal having the same phase to the two magnetic heads, and a position F[] for detecting the phase difference between the device signals reproduced from these two magnetic heads.
A difference detection means, a rotation speed detection means for detecting the rotation speed of the rotation shaft, a helix angle of the rotation shaft is determined based on the detected phase difference and the rotation speed, and the rotation angle is applied to the rotation shaft based on this helix angle. A torque calculation means for calculating torque is provided to detect the torque.

[For production]

The torsion angle θ of the rotating shaft is given by θ−2πΔtN, where Δt is the detected phase difference and N is the detected rotational speed.

Here, the phase difference Δt can be detected by the device signals reproduced from the two magnetic heads, and the rotation speed N can be detected by the rotation speed detection means.

Therefore, the frequency value of the position signal is no longer required to determine the twist angle. Therefore, even if the position signal is not written as an accurate periodic signal, no error occurs when determining the twist angle.

Further, since position signals can be written on two magnetic recording media at any time with the same phase, errors due to installation work or changes over time do not occur.

〔Example〕

The present invention will be described below based on illustrated embodiments. 1st
The figure is a reproduction diagram of a torque detection device according to an embodiment of the present invention. This device has a function of detecting torque applied to the rotating shaft 10. In this embodiment, the rotating shaft 10 is an output shaft of an automatic transmission for an automobile, and its left end in the figure is connected to a drive source, and its right end in the figure is connected to a load. Magnetic recording layers 11 and 12 are formed on the outer circumferential surface of the rotating shaft 10 at a predetermined distance apart. These magnetic recording layers can be formed by applying a magnetic paint in which magnetic powder such as ferrite is dispersed in a resin binder such as Epoquin resin to a predetermined portion of the surface of the rotating shaft 10. Inductive magnetic heads 13 and 14 are arranged close to and opposite the surfaces of the magnetic recording layers 11 and 12. These magnetic heads 13 and 14 have magnetic recording layers 11 and 1.
A predetermined magnetic pattern can be recorded and reproduced with respect to 2. A recording signal for recording the magnetic pattern is generated by the recording circuit 15 and sent to each magnetic field 13.14.
given to. Further, each reproduction signal of the magnetic pattern reproduced by each magnetic head 13, 14 is amplified by an amplifier 16, noise components are removed by a filter 17, and waveform shaped by a waveform shaping circuit 18. The detection circuit 19 is manually operated. The phase difference detection circuit 19 detects the phase difference Δt between the two systems of reproduced signals and provides this to the torque calculation circuit 20.

On the other hand, the rotating shaft 10 has a gear 3 for detecting the number of rotations.
0 is fixed. An electromagnetic pickup 31 is arranged on the circumferential surface of the gear 30, and the passage of each tooth formed at equal pitches on the outer circumference of the gear 30 is detected. This detection signal is given to the rotation speed detector 32. The rotational speed detector 32 generates a signal indicating the rotational speed N of the rotating shaft 10 based on this detection signal, and supplies this to the torque calculation circuit 20. In this way, the torque calculation circuit 20 has a phase difference Δ
t and the rotation speed N are given, and based on these, the rotation axis 1
The torque T added to 0 is calculated and output.

Next, the operation of torque detection by this device will be explained.

This detection operation is reproduced in two stages: a preparation stage in which a predetermined magnetic pattern is written in the magnetic recording layer, and a detection stage in which this magnetic pattern is read out. ! The soldering stage (a) is performed while the rotating shaft 10 is rotating with no load applied to it. In this state, the recording circuit 15 generates a predetermined periodic signal and applies it to the magnetic heads 13 and 14 simultaneously. Specifically, a pulse signal of a predetermined frequency fO is generated, and the magnetic heads 13 and 14 write a magnetic pattern corresponding to this pulse signal into the magnetic recording layers 11 and 12, respectively. Here, this written signal will be referred to as a position signal.

Since the rotary shaft 10 is rotating during the writing operation of the position signal, a magnetic pattern is formed in which marks indicating the peak positions of the pulses are lined up in the circumferential direction of the magnetic recording layer. FIG. 2 shows an example of a magnetic pattern written in this manner.

When the rotating shaft 10 is rotating at a constant speed, the pitch of the position signal written on the magnetic recording layer is constant, and the spatial frequency of the recorded position signal is the frequency of the pulse signal generated by the recording circuit 15. This corresponds to fO. However, in reality, the rotational speed of the rotating shaft 10 is not constant, but constantly fluctuates. Therefore, as shown in FIG. 2, the period of the position signals recorded on the magnetic recording layers 11 and 12 is not constant but varies. However, since the magnetic heads 13 and 14 are simultaneously given the same pulse signal generated by the recording circuit 15, the magnetic recording layer 1
The phases of the position signals written in 1 and 12 become equal. FIG. 3 shows the magnetic recording layers 11 and 1
2 shows a signal waveform when the position signal written in 2 is read out with no load. Here, signal A is the magnetic recording layer 1
The position signal read from the magnetic recording layer 12 and the signal B indicate the position signal read from the magnetic recording layer 12. As mentioned above, these position signals will not necessarily be periodic signals, but will have equal phases. For example, as shown in FIG. 3, the first period P1 and the second period P2 of each signal are not necessarily equal, but the first period of signal A and the first period of signal B are both equal to Pl. , the second period of signal A and the second period of signal B
Both periods are equal to P2.

By writing position signals of the same phase into the magnetic recording layers 11 and 12 in this way, the subsequent detection stage can be performed. This detection step takes place with the rotating shaft 10 under load. In this state, the rotating shaft 10 will be twisted due to the torque generated based on the load, and a phase difference will occur between the position signals read from both magnetic recording layers 11 and 12. FIG. 4 shows signal waveforms when the position signals written in the magnetic recording layers 11 and 12 are read out under load.

Similarly to FIG. 3, signal A indicates a position signal read from the magnetic recording layer 11, signal B indicates a position signal read from the magnetic recording layer 12, and signal C indicates a signal corresponding to the phase difference between the two. Each pulse of signal B is delayed by a phase difference Δt (calculated in units of time) with respect to each pulse of signal A. The single phase difference detection circuit thus detects the phase difference Δt between the two position signals given from the waveform shaping circuit 18 and supplies it to the torque calculation circuit 20.

Next, the calculation processing in the torque calculation circuit 20 will be explained. The relationship between the torsion angle θ of the rotating shaft and the phase difference Δt determined in units of time is θ−2π Δt N
It is given by (1). Here, N is the number of rotations of the rotating shaft per unit time. Above mentioned patent application Hei 1-254
In the torque detection device disclosed in the specification of No. 561, this rotational speed N is determined from the position signal recorded on the magnetic recording layer 11 or 12. That is, if the rotational speed of the rotating shaft when the position signal is written in the preparation stage is NO1, the frequency of the written position signal is fO, and the frequency of the position signal read out in the detection stage is f, then N-( f/fO)/NO(2) The number of rotations N per unit time in the detection stage is determined by the formula: f/fO)/NO(2). In this way, once the torsion angle θ is determined using equations (1) and (2), the torque T is calculated using the equation T-2πθGd4/64L (3). Here, G is the transverse elastic coefficient of the rotating shaft, d is the diameter of the rotating shaft, and L is the magnetic recording layer 11 and 12.
is the distance between In the apparatus disclosed in the above specification, the rotational speed N is determined by equation (2), the twist angle θ is determined by equation (1), and the torque T is calculated by equation (3). In this method, it is necessary to use frequencies f and fO in the calculation of equation (2), but since the rotating shaft does not actually rotate at a constant speed, the pinch of the recorded position signal is not constant. The values of frequencies f and fO are not accurately determined. Therefore, the values detected by the method disclosed in the above specification include errors.

The detection device of the present application was invented with the intention of eliminating this detection error, and the rotation speed N is not determined from a position signal, but is directly detected by the rotation speed detector 32. As mentioned above, the gear 30 has teeth formed at equal pitches, so by detecting the passage of these teeth with the electromagnetic pickup 31, the rotation speed detector 32 detects the rotation speed per unit time of the rotating shaft 10. N can be determined accurately. Substituting equation (1) into equation (3), T-π
2Gd4·Δt-N/16L (4) is obtained. Here, G, d, and L are known constants, and the phase difference Δt
is given by the phase difference detection circuit 19, and the rotation speed N is given from the rotation speed detector 32, so the torque calculation circuit 20
can calculate the torque T based on equation (4).

As described above, the torque detection device according to the present invention has an advantage over the device disclosed in the above-mentioned specification in that the position signals recorded on the magnetic recording layer do not need to be arranged at equal intervals, and Even if variations occur in the rotation, no error occurs in the detected torque value. Therefore, in principle, it is possible to record only a single pulse as a position signal on the magnetic recording layers 11 and 12 (that is, only one peak position is recorded on each magnetic recording layer). do not have. However, when considering the sampling time when performing torque calculation, the expected maximum torque value, the rotation speed of the rotating shaft 10, etc., it is practically preferable to record multiple pulses at as equal intervals as possible. .

Although the present invention has been described above based on an illustrated embodiment, the present invention is not limited to this embodiment only.
It can be implemented in various ways. For example, in the embodiment described above, the combination of gear 30 and electromagnetic pickup 31 is used as a means for detecting the rotation speed of the rotating shaft 10, or any other means may be used to detect the rotation speed. . For example, a slit plate with many slits arranged at equal intervals in the circumferential direction of the rotating shaft is fixed to the rotating shaft,
An optical pickup consisting of a light-emitting element and a light-receiving element may be provided at opposing positions across the slit to detect passage through the slit. Alternatively, in the same way as the magnetic recording layers 11 and 12, a third magnetic recording layer is formed on the rotating shaft 10, and magnetic patterns are recorded thereon at equal intervals, and the magnetic patterns are detected by a magnetic head. You can also play it back. Furthermore, in the above-mentioned embodiment, the magnetic recording layer 11.12 was coated with magnetic paint on the rotating shaft lO, but the magnetic recording layer is formed on the surface of a ring-shaped separate body. may be fixed to the rotating shaft. Alternatively, a magnetic tape used in audio tape recorders or the like may be wound around the rotating shaft and bonded.

〔Effect of the invention〕

As described above, according to the present invention, the phase difference Δt is determined from the position signals read from the two magnetic recording layers on the rotating shaft, and the number of rotations N per unit time of the rotating shaft is determined from the separately prepared rotational speed detection means. Since the torque generated on the rotating shaft is calculated from these, it is possible to accurately detect torque even for a rotating shaft whose rotational speed fluctuates.

[Brief explanation of drawings]

FIG. 1 is a reproduction diagram of a torque detection device according to an embodiment of the present invention, FIG. 2 is a diagram showing an example of a magnetic pattern written on a magnetic recording layer in the device of FIG. 1, and FIG. 3 is a diagram showing a magnetic recording layer. Figure 4 is a signal waveform diagram when the position signal written in the magnetic recording layer is read out under no load, and Figure 4 is a signal waveform diagram when the position signal written in the magnetic recording layer is read out under load. . 10.Rotation axis, 11.12.Magnetic recording layer, 13°14
・Magnetic head, 15... Recording circuit, 16... Amplifier, 17. Filter, 18... Waveform shaping circuit, 19...
Phase difference detection port path, 20...torque calculation circuit, 30...
- Gear, 31 - Electromagnetic pickup, 32... Rotation speed detector, A... Position signal read from the magnetic recording layer 11,
B...Position signal read from the magnetic recording layer 12, C...
Phase difference signal of same position signal, Δt...phase difference, N...
Number of rotations of the rotating shaft per unit time. Figure 1

Claims (1)

[Claims] a first magnetic recording medium formed in the circumferential direction of the rotating shaft;
A second magnetic recording medium is also formed at a predetermined interval in the axial direction with respect to the first magnetic recording medium in the circumferential direction of the rotating shaft, and a predetermined position signal is transmitted to the first magnetic recording medium. A first magnetic head for recording and reproducing a predetermined position signal on the second magnetic recording medium, a second magnetic head for recording and reproducing a predetermined position signal on the second magnetic recording medium, a recording means for applying a position signal having the same phase to the second magnetic head to perform recording; and a recording means for causing the second magnetic head to perform recording by applying a position signal having the same phase; a phase difference detection means for detecting a phase difference; a rotation speed detection means for detecting a rotation speed of the rotation shaft; a torsion angle of the rotation shaft is determined based on the phase difference and the rotation speed; A torque detection device comprising: torque calculation means for calculating the torque applied to the rotating shaft based on the rotational shaft.