JPH055661A - Torque sensor with multifunction - Google Patents

Abstract

(57) [Abstract] [Purpose] In a torque sensor using the applied magnetic effect, the rotational speed of the torque transmission shaft can be detected in a non-contact manner without changing the basic configuration, and the torque, rotational speed and power can also be monitored. It is intended to provide a torque sensor with a function. A coil in which a magnetic material ribbon 2 having magnetostriction is fixed to the surface of a torque transmission shaft 1 and a change in magnetic characteristics due to a stress transmitted from the torque transmission shaft 1 to the magnetic material 2 is wound in a concentric circle of the shaft. In the torque sensor for detecting the torque by changing the impedance of 5, the hole 3 or the void 3a is formed in the magnetic material ribbon 2 and the basic outer circumference is rectangular or parallelogrammatic and fixed in the circumferential direction of the torque transmission shaft 1. In this case, the opposite sides are fixed to each other by facing each other with a gap 3a or closely adhered to each other, and the magnetic core 7 around which the coil 8 is wound is arranged outside the magnetic material ribbon 2 in a non-contact manner with a space between them. The rotation speed of the torque transmission shaft can be detected at the same time as the torque by detecting the shaft rotation speed by detecting the air gap, and the rotation speed detection function can be added to obtain the work rate. ..

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque sensor using a so-called stress magnetic effect in which magnetic permeability changes when stress is applied to a member made of a magnetic material from the outside.

[0002]

2. Description of the Related Art Recently, attention has been paid to the development of a mechanical quantity sensor using the stress magnetic effect. For example, a torque sensor using this principle is described in U.S. Pat. No. 4,823,617 and JP-A-61-312250.

The structure of a conventional torque sensor of this type will be described below with reference to FIG.

As shown in the figure, the amorphous magnetic alloys 22a and 22b are adhered to the torque transmission shaft 21 with an adhesive such as a polyimide resin, and the difference in linear thermal expansion between the two is used to make the temperature higher than the operating temperature range. By hardening, the in-plane internal compressive stress is applied to the amorphous magnetic alloys 22a and 22b. Further, the coil 2 is centered around the torque transmission shaft 21.
3a and 23b are wound and connected to the differential output circuit 24.

When torque is applied to the torque transmission shaft 21, distortion occurs in the amorphous magnetic alloys 22a and 22b. As a result, the magnetic permeability changes due to the stress magnetic effect, and as a result, the inductance of the coils 23a and 23b changes. For example, with respect to the right-handed torque, the inductance of the coil 23a increases and the inductance of the coil 23b decreases. This change can be detected by the differential detection circuit to simultaneously detect the magnitude and direction of the torque.

[0006]

In such a conventional sensor, the amount of torque and the direction of the torque transmitted to the torque transmission shaft 21 can be detected, but it is necessary when the work rate (horsepower) is obtained. The rotation speed of the shaft had to be determined by a rotation speed sensor provided elsewhere. Therefore, the torque sensor itself has a problem that the power cannot be detected.

The present invention solves the above problems, and the rotational speed of the torque transmission shaft can be detected in a non-contact manner without changing the basic structure of the conventional torque sensor, and the torque, the rotational speed and the power can be monitored. It is intended to provide a torque sensor with multiple functions.

[0008]

In order to achieve the above-mentioned object, the present invention fixes a magnetic material ribbon having magnetostriction on the surface of a torque transmission shaft, and transmits the magnetic material ribbon from the torque transmission shaft to the magnetic material ribbon. In a torque sensor that detects torque by changing the magnetic characteristics due to stress by changing the impedance of a coil wound concentrically around the shaft, a hole or gap is formed in the magnetic material ribbon, and the basic outer circumference is rectangular or parallel four sides. When fixing in the circumferential direction of the torque transmission shaft, a gap is provided on the opposite side so as to face each other or closely adhere to each other, and the magnetic core around which the coil is wound has a space outside the magnetic material ribbon. Placed in non-contact via
The rotation speed of the torque transmission shaft is detected at the same time as the torque by detecting the rotation speed of the shaft by detecting the air gap during rotation. Further, by multiplying these two values, the power can be calculated at the same time.

[0009]

According to the present invention, the torque generated in the torque transmission shaft in the above-described structure is detected by the stress-magnetic effect of the magnetic material ribbon having magnetostriction, and when the torque transmission shaft rotates, the magnetic force of the torque transmission shaft is fixed. The difference between the material ribbon and the air gap can be detected by the change in the magnetic resistance in the magnetic circuit formed between the rotating torque transmission shaft and the rotating torque transmission shaft. Is what you can do. Further, the power can be calculated at the same time by multiplying these two values.

[0010]

【Example】

(Embodiment 1) FIG. 1 to FIG. 7 on the first embodiment of the present invention
Will be described with reference to.

As shown in FIG. 1, a rectangular linear thermal expansion coefficient of 7.9 × 10 ⁻⁶ (1 / ° C.) in a rectangular shape in which small rectangular holes 3a are provided at equal intervals in a torque transmission shaft 1 made of titanium having a diameter of 30 mm is positive. A magnetic alloy thin strip 2 of 45% Ni—Fe having a saturation magnetostriction constant and a thickness of 50 μm is adhered by an addition polymerization type polyimide adhesive. The adhesion was performed by rapidly raising the temperature to 250 ° C., which is 100 ° C. higher than the operating temperature of the torque sensor of 150 ° C., and kept at this temperature for 2 hours. By doing so, 45% Ni-F in the operating temperature range of the torque sensor −50 ° C. to + 150 ° C.
It is designed so that in-plane compressive stress acts on the magnetic alloy ribbon 2 of e. Before bonding, 900 ℃, 2 hours, 10
It is heat-treated in a vacuum atmosphere of ^-6 Torr to have a cylindrical shape as shown in FIG. 2, and is arranged so that a gap 3 can be formed on the torque transmission shaft 1 at the time of bonding. The circumferential length of the small rectangular hole 3a provided in the rectangular magnetic alloy ribbon 2 is the same as the circumferential length of the void 3. The bobbin 4 has a torque detecting coil 5
Is wound and attached to a yoke 6 made of a Ni—Fe based magnetic material having a high magnetic permeability. The high-permeability horseshoe-shaped ferrite magnetic core 7 has a gap length approximately equal to the circumferential length of the void 3 and the small rectangular hole 3a, and has a space outside the rectangular magnetic alloy ribbon 2 of 45% Ni-Fe. It is arranged in a non-contact manner. Further, a rotation speed detecting coil 8 is wound around the magnetic core 7. The torque detecting coil 5 and the rotational speed detecting coil 8 are driven at 10 kHz, respectively, and lead wires 10a, 1 are connected to an electric circuit 9 including a torque and rotational speed detecting circuit.
Wired at 0b.

FIG. 3 shows the principle of rotation speed detection in the torque sensor, and a typical state in which the torque transmission shaft 1 is rotating is shown in FIGS. 3 (a) and 3 (b). In the case of FIG. 3 (a),
The magnetic core 7 and the rectangular alloy thin ribbon 2 of 45% Ni-Fe form a magnetic circuit through a space. Further, in the case of FIG. 3B, the magnetic circuit does not include the rectangular-shaped magnetic alloy thin ribbon 2 of 45% Ni—Fe, and the space portion of the magnetic circuit becomes large. Therefore, compared to the impedance value Za of FIG. 3 (a),
The impedance value Zb in FIG. 3 (b) becomes smaller. Figure 3
In the state of (b), the number of small rectangular holes 3a + 1 times occurs every rotation of the torque transmission shaft 1 + 1 times, so the rotation speed can be measured by measuring this impedance change. In this rotation speed measurement, the impedance value of the rotation speed detection coil 8 is
It changes depending on the magnitude of the torque value applied to the torque transmission shaft 1 and the fluctuation of the air gap between the torque transmission shaft 1 and the magnetic core 7 due to rotation. Therefore, it is necessary to design the impedance value Zb of FIG. 3 (b) to be a small value exceeding these change widths, but the gap length of the magnetic core 7 is the same as the circumferential length of the air gap 3. If it is less than or equal to this level, this condition is satisfied.

FIG. 4 shows the relationship between the torque and the impedance value in the torque sensor. This relationship can be obtained with an accuracy of ± 1% FS (full scale) even when the torque transmission shaft 1 is stationary or rotating. This high precision occurs because the in-plane compressive stress is constantly applied to the magnetic alloy ribbon 2 of 45% Ni—Fe in the operating temperature region as described above, and the precision is deteriorated without this means. The torque detection coil 5 is incorporated in the bridge circuit shown in FIG.
Output as C (DC) voltage. Further, FIG. 6 shows changes in the voltage across the rotation speed detection coil 8 when the rotation speed detection coil 8 is connected to the power source in series with the fixed resistor R. The rotation causes a spike-shaped voltage drop. A voltage value V _L that is equal to or less than the voltage variation across the rotation speed detection coil 8 due to torque variation and rotation is set as a threshold value, and a comparator and a counter are passed through to detect the number of times per unit time that is less than or equal to this value. With this, the rotation speed can be detected. Moreover, the output from the counter can be converted into a DC voltage, and the DC voltage obtained by converting the average torque value at the sampling time into the DC voltage can be multiplied by the multiplication circuit to output the power. A block diagram of this circuit is shown in FIG.
Shown in.

As described above, it is possible to construct a sensor that can detect the rotational speed of the torque transmission shaft 1 at the same time as the highly accurate torque detection, and thereby obtain the work rate at the same time. These three outputs can be taken out individually.

In this embodiment, the void 3 is not particularly necessary,
The same rotation speed can be detected by using only the small rectangular hole 3a. However, when the rectangular magnetic alloy ribbon 2 of 45% Ni-Fe is used, the magnetic resistance of that portion is reduced even if the void 3 is made small. Since this exists, it is preferable to utilize this gap for rotation speed detection.

(Embodiment 2) A second embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 8, the torque transmission shaft 11 is made of steel (JIS S35C) having a diameter of 10 mm. Linear thermal expansion coefficient 11.0 × 10 ^-6 (1 / ° C), saturation magnetostriction constant 16 × 10
Fe-Ni-Si-B type rectangular amorphous magnetic alloy thin strips 12a and 12b having ^-6 are symmetrically provided with slits at ± 45 °. As shown in FIG. 9, a rectangular amorphous magnetic alloy thin ribbon 12b has a U-shaped void 13c formed on the side thereof and has a cylindrical shape, and is bonded to the torque transmission shaft 11 with an addition polymerization type polyimide adhesive. The in-plane compressive stress always acts within the operating temperature range. At the time of bonding, the bonding is performed so that the voids 13a and 13b are formed as in the first embodiment. Coils 15a and 15b are wound around the coil winding bobbins 14a and 14b. 16 is a ferrite yoke having a high magnetic permeability. The principle of torque detection is the same as that of the first embodiment, but since this embodiment has shape anisotropy at an angle of ± 45 °, a torque difference is generated simultaneously with the magnitude of the torque by the differential circuit as shown in FIG. The direction of can also be detected. The output characteristics are shown in FIG.

A high-permeability horseshoe-shaped ferrite magnetic core 17a,
17b has a small gap length, which is about half the circumferential length of the void, and has rectangular amorphous magnetic alloy ribbons 12a and 12b.
Are arranged in a non-contact manner on the outside of each of them via a space.
Further, rotation speed detection coils 18a and 18b are wound around the magnetic cores 17a and 17b, respectively. Reference numeral 19 is an electric circuit including a torque, rotation speed and power detection circuit. Each coil is driven at 30 kHz. Two
0a and 20b are the torque detection coil and the electric circuit 19,
Further, 20c and 20d are conducting wires respectively connecting the rotation speed detecting coil and the electric circuit. The rotation speed detection principle is the same as that of the first embodiment, but in this embodiment, the rotation speed detection coils 18a and 18b are formed by a bridge circuit similar to that shown in FIG. The differential is taken to make the detection of the air gap 13c more accurate.

As described above, the sensor of this embodiment can measure the magnitude, direction, and rotation speed of torque. With this, similarly to the first embodiment, the power can be obtained from the product of the torque magnitude and the rotation speed. These three outputs can be taken out individually.

In the present invention, the linear coefficient of thermal expansion of the torque transmission shaft is larger than the coefficient of thermal expansion of the magnetic material ribbon having magnetostriction, and the bonding is performed at a temperature higher than the sensor operating temperature, so that the magnetostriction is always present in the operating temperature range. An example of applying in-plane compressive stress to the magnetic material ribbon has been described. As a result, it is possible to realize a sensor with extremely small hysteresis and little change in temperature characteristics of the sensor. If this technique is not used, hysteresis appears on the contrary, and the sensor has a large change in temperature characteristics, which makes it unsuitable for a torque sensor.

In the present invention, the magnetic material ribbon is 45%.
The Ni—Fe magnetic material ribbon and the amorphous alloy ribbon have been described. This ribbon may be a magnetic material having a high magnetic permeability having magnetostriction, but especially in an amorphous magnetic alloy, the material composition can be freely changed, and the material constants such as the coefficient of thermal expansion with the torque transmission shaft can be changed. Since it is easy to adjust and has excellent magnetic properties, it is optimal as a torque detection material.

[0022]

As is apparent from the above description of the embodiments, according to the present invention, the magnitude, direction and rotational speed of torque can be simultaneously measured with a simple structure,
As a result, it is possible to provide an inexpensive and multifunctional sensor that can also obtain the work rate. It is expected that these sensors will make a great contribution to the control of automobiles, robots, etc. in the future.

[Brief description of drawings]

FIG. 1A is a partial sectional front view of a torque sensor according to a first embodiment of the present invention, and FIG. 1B is a sectional view taken along line AA of FIG.

FIG. 2 is a perspective view of a cylindrical and rectangular 45% Ni—Fe magnetic alloy ribbon before and after heat treatment in the first embodiment.

FIG. 3A is a diagram showing the principle of rotation speed detection in the torque sensor of the first embodiment. FIG. 3B is a diagram showing the principle of rotation speed detection in the torque sensor of the first embodiment.

FIG. 4 is a torque output characteristic diagram of the same.

FIG. 5 is a torque detection bridge circuit diagram of the same.

FIG. 6 is a diagram showing a change in voltage across the rotation speed detection coil.

FIG. 7 is a block circuit diagram for outputting the work rate.

FIG. 8A is a partial sectional front view of a torque sensor according to a second embodiment of the present invention, and FIG. 8B is a sectional view taken along line BB of FIG.

FIG. 9 is a perspective view of cylindrical and rectangular amorphous magnetic alloy ribbons before and after heat treatment in the second embodiment.

FIG. 10 is a torque detection bridge circuit diagram of the second embodiment.

FIG. 11 is the same torque output characteristic diagram.

FIG. 12 is a partial front view of a conventional torque sensor.

[Explanation of symbols]

 1 Torque Transmission Shaft 2 Magnetic Alloy Thin Band 3 Void 3a Hole 5 Torque Detection Coil 7 Horseshoe Ferrite Core 8 Rotation Speed Detection Coil 9 Electric Circuit

Claims (1)

Claims: 1. A torque transmission shaft having a magnetic material ribbon fixed to the surface thereof, and a coil provided concentrically with the torque transmission shaft.
In the case where a detection circuit for detecting impedance change of the coil is provided, holes or voids are formed in the magnetic material ribbon, and the basic outer circumference is rectangular or parallelogram, and fixed in the circumferential direction of the torque transmission shaft. Air gaps are provided on opposite sides to face each other or adhere closely to each other, and the magnetic core around which the coil is wound is placed outside the thin ribbon of magnetic material in a non-contact manner via a space, and axis rotation is performed by detecting air gap during rotation. A multi-function torque sensor that detects the number of revolutions of the torque transmission shaft at the same time as the torque by detecting the number of revolutions. 2. A magnetic material having a linear thermal expansion coefficient larger than that of a magnetic material ribbon having a magnetostriction, the torque transmission shaft being bonded at a temperature higher than a sensor operating temperature, and having a magnetostrictive coefficient in the operating temperature range. The multifunctional torque sensor according to claim 1, wherein an in-plane compressive stress is applied to the ribbon. 3. The multifunctional torque sensor according to claim 1, wherein the magnetic material fixed to the surface of the torque transmission shaft is an amorphous magnetic alloy having magnetostriction. 4. The multi-function torque sensor according to claim 1, further comprising a multiplication circuit that detects the rotational speed at the same time as the torque detection, multiplies the rotational speed by the torque, and outputs the power.