JPS60192233A - Torque sensor - Google Patents

Abstract

PURPOSE:To improve the S/N of a torque sensor and the perform stable detection, by using a gate pulse signal synchronized with the number of revolutions of a torque transmission shaft and obtaining the change in the magnetic characteristic of a specific section in the peripheral direction of a thin strap of a magnetic metal as detection signals in one detection signal per one rotation. CONSTITUTION:Annular magnetic cores 221 and 222 are fixed to the outer perriphery of a torque transmission shaft 21 made of a ferromagnetic substance and induced magnetic anisotropies are given in advance to the magnetic cores 221 and 222 in directions respectively inclined at angles +theta and -theta against the peripheral direction of the magnetic cores 221 and 222. Moreover, U-shaped magnetic cores 231 and 232 for detection made of an oxide magnetic substance are respectively arranged above the annular magnetic cores 221 and 222 in the peripheral direction of the magnetic cores 221 and 222 under non-contacting conditions. Torque detection is performed by using output voltages obtained from specific sections of the magnetic cores 221 and 222 as detection signals in one signal per one rotation by utilizing a gate pulse signal synchronized with the number of revolutions of the torque transmission shaft 21.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a torque sensor that detects torque without contact.

[Technical background of the invention]

Torque is one of the basic quantities when controlling a rotational drive system. In order to accurately detect torque, the detection mechanism must be of a non-contact type.

In recent years, a non-contact torque sensor as described above that uses a thin strip of amorphous magnetic alloy has been proposed (IEE of Japan Magnetics Study Group Materials MAG
-81-72).

The general structure of this torque sensor is as shown in FIG. In the figure, reference numeral 1 denotes a rotating shaft on which torque is to be detected, that is, a torque transmission shaft.A ring-shaped magnetic core 2 made of an amorphous magnetic alloy is wound around and fixed to this torque transmission shaft 1. This annular magnetic core 2 is previously given an induced magnetic anisotropy Ku' 4 in a direction inclined at an angle θ with respect to its circumferential direction 3. Note that, for example, a detection coil (not shown) is disposed close to the annular magnetic core 2, and this detection coil is further connected to a detection circuit (not shown).

The principle of the torque sensor described above will be schematically explained.

Here, in order to simplify the explanation, it is assumed that θ>45° and the saturation magnetostriction constant λB>0. Now, torque 5 is applied to torque transmission shaft 1.
When , the strain stress generated in the torque transmission shaft 1 is transmitted to the annular magnetic core 2, and a tension force σ is generated in the annular magnetic core 2 in the +45° direction and a compressive stress -σ is generated in the -45° direction. Along with this, the annular magnetic core 2 has an induced magnetic anisotropy Ku"6 (=3λB) in the +45° direction due to the magnetostrictive effect.
・σ) is induced. As a result, the induced magnetic anisotropy changes to Ku7 as a combination of Ku' and Ku''. Generally, the magnetic permeability of a magnetic material changes depending on the direction of the induced magnetic anisotropy with respect to the excitation direction. Changes in magnetic permeability due to changes in the direction of induced magnetic anisotropy can be measured, for example, as changes in stain pressure using a detection coil and a detection circuit connected thereto, and from that value, the torque transmission axis 1 can be measured.
Torque 5 applied to can be detected.

In addition, in the above description of the torque sensor, a case was described in which an amorphous magnetic alloy was used as the magnetic material constituting the annular magnetic core, but the present invention is not limited to this, and as long as it exhibits soft magnetism, for example, permalloy (Fe-Ni alloy), Sendust (
Other magnetic materials such as Fe-At-St gold alloy and Fe-8t alloy can be used.

By the way, as mentioned above, torque can be detected by arranging a detection coil close to the annular magnetic core made of a thin magnetic metal strip, but the detection mechanism is an important factor that affects the performance of the torque sensor. .

Conventionally, the above-mentioned detection mechanism is as shown in Figs. 2(a) and (b).
) are known.

In FIG. 2(a), an annular magnetic core 12 made of a magnetic metal ribbon is fixed to a hollow torque transmission shaft 11, and a solenoid coil 13 is used to excite the annular magnetic core 12 in the circumferential direction.
The output is detected by winding the wire. Also, the same figure (b)
An annular magnetic core 12 made of a thin magnetic metal strip is fixed to a torque transmission shaft 11, and a solenoid coil 13' wound around the outer circumference is used to excite the annular magnetic core 12 in the width direction, and a detection winding 14' is installed outside the annular magnetic core 12. The output is detected by winding the wire.

In other words, in both the detection mechanisms shown in Figures 2 (a) and (b), changes in magnetic permeability are interpreted as changes in voltage due to mutual induction between the solenoid coil and the detection winding, and an output is obtained via an amplifier circuit. It is something.

[Problems with background technology]

However, as shown in Fig. 2(b), it is difficult to make a device that excites the annular magnetic core in the width direction, making it small and unable to store it in a narrow space.
Since an excitation current of mA or more is required, there are disadvantages in terms of the magnetic circuit.

In addition, as shown in Fig. 2 (a), in the case where the annular magnetic core is excited in the circumferential direction, the magnetic permeability of the entire circumference of the annular magnetic core is continuously detected, so it is necessary to keep the magnetic permeability of the -circumference to a constant value. be. However, when a ferromagnetic material such as Fe-based material is used as the torque transmission shaft, magnetic permeability changes within one revolution due to non-uniformity of the material.

Therefore, the output fluctuation caused by this change in magnetic permeability is superimposed on the torque detection output, resulting in significant deterioration of the eyes.

[Purpose of the invention]

The present invention was made in order to eliminate the above-mentioned drawbacks.It is small in size, requires a small excitation current, and has low S/N
The present invention aims to provide a torque sensor that can perform stable torque detection by improving the ratio.

[Summary of the invention]

The torque sensor of the present invention uses a dart pulse signal synchronized with the rotation speed of the torque transmission shaft to change the magnetic properties of a specific part of the circumferential direction of a magnetic metal ribbon fixed to the torque transmission shaft in one rotation. This is characterized in that torque detection is performed by obtaining one detection signal.

According to such a torque sensor, since a gate pulse signal having a pulse period and pulse width synchronized with the rotational speed is used, changes in the magnetic properties of a specific portion of a rotating magnetic metal ribbon can be equivalently detected. Can be detected under stationary conditions. Therefore, even if the magnetic permeability of the magnetic metal ribbon is not always a constant value on the circumference of the torque transmission shaft, accurate torque detection can be performed. In addition, Fe is used as the torque transmission shaft.
Even if a ferromagnetic material such as a ferromagnetic material is used, there is no output fluctuation caused by changes in magnetic permeability, and stable torque detection can be performed with a high S/N ratio.

Moreover, according to such a torque sensor, a low excitation current is required to obtain the same output, and S even when excited in the circumferential direction.
It is possible to obtain an output with a good /N ratio. In other words, when a magnetic metal ribbon is wound around a torque transmission shaft, excitation in the width direction requires a much larger excitation current than in the circumferential direction due to the demagnetizing field coefficient. On the other hand, in the case of excitation in the circumferential direction, a low excitation current is required, but when considering maintaining the uniformity of magnetic permeability of the magnetic metal ribbon, some problems remain compared to the case of excitation in the width direction. However, according to the present invention, this uniformity can be sufficiently covered and is very effective. Moreover, this magnetic metal ribbon may not be completely wound but may be provided partially.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 3 to 5.

In FIG. 3, a torque transmission shaft 2 made of a ferromagnetic material with a diameter of 55 m is rotated by a drive source such as a motor (not shown).
1 has an annular magnetic core 22□ on its outer periphery.

222 is fixed. These annular magnetic cores 221°22
2 is manufactured by a single roll method with a width of 5 mm and a thickness of 30 μm.
(FeO265Nio, 3CrO105)75S11
A thin ribbon of 1B14 alphus magnetic alloy is wound around the torque transmission shaft 2 and fixed thereto. These annular magnetic cores 221 r222 are given in advance induced magnetic anisotropy in the direction of angle 〇 and angle -〇 in the circumferential direction, respectively.

Above these annular magnetic cores 2”1 m 222 are U-shaped detection magnetic cores 231 and 232 made of oxide magnetic material, respectively.
are arranged circumferentially in a non-contact manner. These magnetic cores for detection 231 and 232 are connected to excitation coils 241 and 24, respectively.
2 and detection coils 251 and 252 are provided.

The annular magnetic core 221 is generated using a gate pulse signal synchronized with the rotation speed of the torque transmission shaft 21.

FIG. 4 shows a circuit configuration for detecting torque by using the output voltage obtained from a specific portion of the motor 222 as one detection signal per rotation.

Instead, the excitation coils 241 and 242 attached to the detection cores 231 and 232 are summation-coupled, and the detection coils 251 and 251.
252 is a differential coupling, and the sine wave obtained from the oscillator 26 is applied to the excitation coils 241 and 242, and the annular magnetic core;
! 21*222 Energizes the entire torque transmission shaft 210 in the circumferential direction. Now, when torque is applied to the torque transmission shaft 21,
Depending on the direction of induced magnetic anisotropy given in advance, the annular magnetic core 22! , 222 respectively increase or decrease in magnetic permeability. This amount of change is converted into a sine wave voltage by the detection coils 251 and 252, and added to the detection circuit 27, and further to the integration circuit 2.
8 and the A/D converter 29 to the sample hold circuit 30. On the other hand, a rotation speed sensor 3 is installed at another position on the torque transmission shaft 21.
A rotation speed signal obtained by the rotation speed sensor 31 is sent to a dirt pulse generation circuit 32, and a dirt pulse signal having a pulse period and pulse width synchronized with the rotation speed is sampled and held. Introduced into circuit 3θ.

In the sample and hold circuit 30, the output voltage due to a change in the magnetic properties of a specific part of the diurnal cycle of the annular magnetic core 221, 222 fixed to the torque transmission shaft 2 is calculated by 1. It can be obtained as one digital output value per revolution. Furthermore, by converting this digital output value (r) into a 9DC analog output voltage using the D/A converter 33, stable torque detection with high S can be performed.

According to the torque sensor of the present invention, by using a dart pulse signal having a pulse period and a pulse width synchronized with the rotation speed of the torque transmission shaft 21, Changes in the magnetic properties of a particular part of the whole can be equivalently detected under stationary conditions. Therefore, even if the magnetic permeability of the magnetic metal ribbons 221 and 222 fixed on the circumference of the torque transmission shaft 21 is not always constant on the circumference, torque can be accurately detected. Furthermore, even if a ferromagnetic material such as Fe-based material is used as the torque transmission shaft 2, there is no output fluctuation caused by changes in its magnetic permeability.
, stable torque detection with high S can be performed.

Furthermore, the entire device can be downsized and can be stored in a narrow space.

In fact, using the above torque sensor, the torque transmission shaft 21 ON
When the dynamic torque was detected at = 200 Orpm, it was found that it had extremely excellent linearity as shown in FIG.

Note that the output in Fig. 5 is the digital output value converted into stain pressure by the D/A converter 33, but any D/A converter can be used.
The A converter allows the output to be made variable. Furthermore, since the digital output value can be directly introduced into the microcomputer, there is great added value.

In addition, although digital signal processing was performed in the above embodiment,
Similar results were obtained even if the VD converter 29 and the D/A converter 33 were omitted and the sample and hold circuit 30 processed the analog signal.

Note that the same effect as in the above example can be obtained when permalloy, sendust, or Fe-3t alloy is used as a magnetic metal thin ribbon.
In addition, amorphous alloy, permalloy,
It was also obtained when Sendust and Fe-8 alloy were used.

In addition, in the torque sensor of the above embodiment, the annular magnetic core is fixed around the entire circumference of the torque transmission shaft, but even when dynamic torque is detected by fixing the entire magnetic metal thin strip only to a part of the circumferential direction of the torque transmission shaft, the same method can be used. A stable output voltage with a high SlN ratio can be obtained.

Furthermore, in the above embodiment, two detection cores were used, and the excitation coil was summatively coupled and the detection coil was differentially coupled, but if it is not necessary to know whether the torque is positive or negative, one detection core may be used. You can just do that.

Further, even when two detection magnetic cores are used, the detection coil may be a summation coupling. However, positive and negative torque ′ff
:, In order to detect with good linearity and high output, it is desirable to have a configuration like the above embodiment.

〔Effect of the invention〕

As detailed above, according to the present invention, the torque of the torque transmission shaft made of a wide range of materials can be transmitted with a high S/N ratio without being affected by changes in the material of the torque transmission shaft or the magnetic permeability within the magnetic metal ribbon. It is possible to provide a torque sensor that is industrially extremely practical, such as being able to stably detect the torque.

[Brief explanation of the drawing]

Figure 1 shows the principle of a non-contact torque sensor, Figure 2 (
a) and (b) are respectively configuration diagrams of conventional torque sensors, FIG. 3 is a configuration diagram of a torque sensor according to an embodiment of the present invention, FIG. 4 is a circuit configuration diagram of the same torque sensor, and FIG. 5 is a diagram of the same torque sensor. FIG. 3 is a characteristic diagram of dynamic l/lux detection by a sensor. 2...Torque transmission shaft, 221 m 222...
Annular magnetic core, 23. ．． 232...Detection magnetic core, 241
. 242... Excitation coil, 251.252... Detection coil, 26... Oscillator, 27... Detection circuit, 2
8...Integrator circuit, 29...Member converter, 30...
・Sample hold circuit, 31... rotation speed sensor, 3
2... Keystone generation circuit, 33... D/A
converter. Applicant's representative Patent attorney Takeshi Suzue Figure 1 Figure 3 Figure 4 Figure 5 Procedural amendments Showa qO.6. ．． 13th Commissioner of the Japan Patent Office Mr. Manabu Shiga■, Indication of Case Patent Application No. 1987-47907 2, Title of Invention 1. Ruli Sensor 3. Person making amendment Relationship with the case Patent Applicant (307) Shares Company Toshiba 4, Agent 6, Subject of amendment 7, Contents of amendment (1) The scope of claims will be corrected as shown in the attached sheet.゛(2)
From line 11 on page 6 of the specification to line 12 on the same page, “1
Delete "one per rotation". (3) Add the following sentence after the fourth line of page 13 of the specification. Furthermore, in the above embodiments, the case where one detection signal is obtained per rotation has been explained, but the invention is not limited to this, and by generating multiple gate pulse signals per rotation, one detection signal can be obtained.
A plurality of detection signals fj) may be generated per rotation. 2. Claims A magnetic metal ribbon having magnetostriction is fixed to a torque transmission shaft,
In a torque sensor that performs non-contact detection of torque by utilizing the change in the magnetic properties of the magnetic metal ribbon due to the torque applied to the torque transmission shaft, a gate pulse synchronized with the rotational speed of the torque transmission shaft. A torque sensor characterized in that torque is detected by using a signal to obtain a change in magnetic properties of a specific portion of the magnetic metal ribbon in a circumferential direction as a detection signal. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] A magnetic metal ribbon having magnetostriction is fixed to a torque transmission shaft, and non-contact detection of torque is performed by utilizing the fact that the magnetic properties of the magnetic metal ribbon change due to the torque applied to the torque transmission shaft. In the torque sensor, a dart pulse signal synchronized with the rotational speed of the torque transmission shaft is used to detect changes in the magnetic properties of a specific portion of the magnetic metal ribbon in the circumferential direction.
A torque sensor characterized in that torque is detected by obtaining one detection signal for each rotation.