JPS6183927A - Torque sensor - Google Patents

Abstract

PURPOSE:To enable stable detection of torque with a high output and a high S/N ratio while facilitating mounting in a small space, by fixing magnetic thin metal strips each imparted magnetic anisotropy partially in a pair on the same circumference of a torque transmission shaft circumferentially to arrange a detection magnetic core differentially connected to a detection winding in proximity thereto. CONSTITUTION:A pair of magnetic thin metal strips 221 and 222 are fixed with an adhesive at two points shifted by 180 deg. on the same circumference of a torque transmission shaft 21 circumferentially. A large induction magnetic anisotropy KU' is imparted to the thin metal strip 221 in the direction inclined by an angle thetato the circumferential direction X of the shaft 21 while to the thin metal strip 222 in the direction inclined by -theta thereto. On the other hand, detection magnetic cores 231 and 232 are provided with excitation windings 241 and 242 and detection windings 251 and 252, which are connected differentially. Thus, as one pair of the detection magnetic cores 231 and 232 are arranged on the same circumference, less width thereof is required for the mounting and as the detection of a torque is done partially in the circumferential direction, there is less effect of non-uniformity in the material of the 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 using a thin strip of amorphous magnetic alloy has been proposed (IEE of Japan Magnetics Study Group Materials MAG
-81-72).

The schematic structure of this torque sensor is as shown in FIG. In FIG. 5, the rotating shaft on which torque is to be detected,
That is, an annular magnetic core 2 made of an amorphous magnetic alloy is wound and fixed around the 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, to simplify the explanation, it is assumed that θ>45° and the saturation fO magnetostriction constant λsho. Now, when torque 5 is applied to the torque transmission shaft 1, the strain stress generated on the torque transmission shaft 1 is transmitted to the annular magnetic core 2, and the annular magnetic core 2 receives a tension σ in the +45° direction and -45° direction. A compressive stress −σ is generated respectively. Along with this, the annular magnetic core 2 has induced magnetic anisotropy Ku''6 (Ku
″−3λS・σ) is induced. As a result, Ku′ and K
u'', the induced magnetic anisotropy changes to Ku7. Generally, the magnetic permeability of a magnetic material changes depending on the direction of the induced magnetic anisotropy with respect to the excitation direction.

Therefore, the change in magnetic permeability due to the change in the direction of the induced magnetic anisotropy of the annular magnetic core 2 can be measured as a change in voltage using, for example, a detection coil and a detection circuit connected to the detection coil, and from that value, the torque can be transmitted. The torque 5 applied to the shaft 1 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 forming the annular magnetic core. , Sendust (
Other magnetic materials such as Fe-ΔC3i alloy) and Fe-8i 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. 6(a) and (b).
) are known.

Fig. 6 (a) shows an annular magnetic core made of a thin magnetic metal strip fixed to a hollow torque transmission shaft 11, excited in the circumferential direction of the annular magnetic core 12 using a solenoid coil 13, and further wound with a detection winding 14 to output an output. In addition, in the same figure (b), an annular magnetic core 12 made of a magnetic metal ribbon is fixed to a torque transmission shaft 11,
The solenoid coil 13' wound around the outer circumference is used to excite the annular magnetic core 12 in the width direction, and the detection winding l! 14' is wound to detect the output.

In other words, both of the detection mechanisms shown in Figures 6(a) and (b) treat changes in magnetic permeability as changes in voltage due to mutual induction between the solenoid coil and the detection winding, and obtain an output via an amplifier circuit. It is.

[Problems with background technology]

In order to bring the linearity of the torque detection output to a practical level in the detection mechanism as described above, at least one pair of differentially coupled detection magnetic cores is required. However, when used as a torque detection device for a rotating shaft of an automobile internal combustion engine, a certain amount of width is required, making installation extremely difficult. In recent years, the space within the engine compartment has become increasingly narrow, making installation even more difficult.

In addition, in order to bring the torque detection output during rotation to a practical level, it is necessary to give a large induced magnetic anisotropy to the annular magnetic core that is wound and fixed around the torque transmission shaft. It is extremely difficult to impart orientation. Furthermore, since the torque is detected continuously over the entire circumference of the torque transmission shaft, it is necessary to keep the magnetic permeability to a constant value at any position. When using the outer body in 4., the material is not restricted ↑ (one round from 1).

Toru 6! j rate change occurs. Therefore, this permeability, 6
Since the output fluctuation caused by the change is multiplied by Φ on the detected torque output, the S/N ratio decreases significantly.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned drawbacks, and it can be easily taken up even when there is a very small space for installing an internal combustion engine in an automobile. 'g
, b, high output, +n S/N LP, -c, it is an attempt to provide a 1-lucren 1 that can perform stable torque detection.

[Summary of chewing]

The torque sensor of the present invention has a plurality of magnetic metal thin strips partially fixed on the same circumference in the circumferential direction of a torque transmission shaft so as to form a pair or a number of stages, and a magnetic metal ribbon forming L7-1. Magnetism in a thin strip in different directions relative to the circumferential direction? In addition to imparting cylindrical properties, n pairs of detection magnetic cores are disposed close to the above-mentioned J1 river metal ribbon, and detection windings are applied to these detection cores. The feature is that the lines are differentially connected.

According to such a torque sensor, since multiple detection magnetic cores exist on the same circumference, the width required for installation is narrower than before, and installation can be done even when the space is narrow, such as in an automobile internal combustion engine. Can be installed easily. In addition, since the magnetic metal ribbon is partially fixed in the circumferential direction of the torque transmission shaft, it is possible to impart a large induction anisotropy in advance, and it is not affected by the non-uniformity of the material of the torque transmission shaft. Therefore, stable torque detection can be performed with high output and high S/N ratio.

[Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1(a) to (C).

In Fig. 1(a), in the circumferential direction of the torque transmission shaft 21 made of a ferromagnetic material with a diameter of 55 mm, there are a pair of... 221 and 222 are fixed with adhesive.

These magnetic metal thin strips 22z and 222 have a width of 5'mm and a thickness of 30p (Feo, . . . , Coo, . . ) 78 S ia B
The t4 amorphous magnetic alloy strip was cut into a length of 1Qmm. In addition, the magnetic metal ribbon 221 has a first
As shown in FIG. 1(B), the torque transmitting shaft 21 is attached to the magnetic metal ribbon 222 in a direction inclined at an angle θ (for example, +45°) with respect to the circumferential direction X of the torque transmitting shaft 21, as shown in FIG. 1(C).
Induced magnetic anisotropy Ku' is given to each inclination direction at an angle -θ (for example, -45°) with respect to the circumferential direction X. Furthermore, a pair of U-shaped detection magnetic cores 231 and 232 are disposed on the outer periphery of the rotating surfaces of the magnetic metal thin strips 22+ and 222 with a gap of 111 m in between. Excitation windings 241.242 and detection windings 251.252 are provided on these detection magnetic cores 231.23z, respectively. The back detection winding 251 and the detection winding 252 are differentially connected.

According to the above torque sensor, since the pair of detection magnetic cores 23r and 232 are disposed on the same circumference of the outer circumference of the torque transmission shaft 21, the width required for installation is narrow, and the crankshaft of an internal combustion engine for an automobile can be used. Installation in the direction of the rotational axis, such as a shaft, is easy even when the space is narrow.

Furthermore, the detected objects of the detection magnetic cores 231 and 232 of the torque sensor are a pair of magnetic metal thin strips 221 and 222 that are partially fixed in the circumferential direction of the torque transmission shaft 21; Since the length is shorter than in the case of winding a magnetic metal ribbon, a large induced magnetic anisotropy can be imparted in advance. Moreover, since torque is detected only in a part of the circumferential direction of the torque transmission shaft 21, it is less affected by non-uniformity of the material of the torque transmission shaft 21, and output fluctuations per rotation are almost eliminated. Since the conditions are equivalent to a stationary state, stable torque detection with a high S/N ratio is possible. On the other hand, since the detection windings 25'1.252 attached to the detection magnetic cores 23+ and 232 are differentially connected, it is easy to set the output to zero when the torque load is zero, and the torque change is effectively amplified. Furthermore, detection with improved linearity is possible. In fact, when the above-mentioned torque sensor was used to detect the dynamic torque of the torque transmission shaft 21 at a rotation rate of 1500 rpm, as shown in Fig. 2, a high S/N ratio, stable detection characteristics with excellent linearity were obtained. I was able to do that.

Furthermore, in the above torque sensor, one peak of inductance P is obtained per revolution as shown in FIG. Therefore, when the torque load fluctuates periodically as in the case of internal combustion engines for automobiles, a detected value at a specific point can be obtained with high reliability. Furthermore, the rotational speed of the torque transmission shaft 21 can also be obtained by introducing the output signal into a counter such as a counter. Furthermore, when m pairs of magnetic metal ribbons are fixed under the same conditions, a small number of peaks of inductance P can be obtained per revolution.

In addition, in the above embodiment, a pair of magnetic metal ribbons were fixed to the torque transmission shaft, and a pair of detection magnetic cores were provided correspondingly, but the present invention is not limited to this. are fixed, and magnetic metal thin strips 32 are placed at four locations on the same circumference at 90° different rotation angles.
*, 322.323.324 are fixed with adhesive.

Among these, magnetic metal thin strips 321, 322.332, 333.333, 334.334, and 3 are adjacent to each other.
The three summers form a pair. The magnetic metal ribbons 321 and 3
23 is applied in a direction inclined at an angle of 45° to the circumferential direction X of the torque transmission shaft 31 as shown in FIG. Induced magnetic anisotropy Ku' is given to each direction at an angle of -45° with respect to the circumferential direction X of the transmission shaft 31, and the induced magnetic anisotropy given to the paired magnetic metal thin strips is are in different directions with respect to the circumferential direction of the torque transmission shaft 31. Furthermore, U-shaped detection magnetic cores 331 to 3ζ34 are arranged on the outer periphery of the rotating surface of the magnetic metal thin strips 321 to 324 with a gap of 1 mm between them, and the adjacent detection magnetic cores 33r and 332 and the detection magnetic core 333 and 334
are paired with each other. These detection magnetic cores 331 to 33
4 are provided with excitation windings 341 to 344 and detection windings 351 to 354, respectively. Of these, the detection winding 35
1 and 352 and detection windings 353- and 354 are differentially connected, respectively.

According to the torque sensor in which two pairs of magnetic metal ribbons are fixed to the torque transmission shaft and two pairs of detection magnetic cores are provided correspondingly to these, two inductance peaks can be obtained per rotation. Therefore, signals at two specific locations in the circumferential direction of the torque transmission shaft can be detected in time series, and S/
Transient response is improved without impairing the N ratio. Such transient response improves dramatically as the number of paired magnetic metal ribbons and detection cores increases.

It has been confirmed that the same effect as in the above example can be obtained when other magnetic materials such as permalloy, sendust, and Fe-8i alloy are used as the magnetic metal ribbon.

〔Effect of the invention〕

As detailed above, according to the torque sensor of the present invention, it can be easily installed even when the space is extremely narrow, such as in an internal combustion engine for self-help vehicles, and it also has high output and high S/N.
This has remarkable effects such as making it possible to detect torque more stably with the ratio.

[Brief explanation of drawings]

FIG. 1(a) is a schematic configuration diagram of a torque sensor according to an embodiment of the present invention, and FIG. 1(C) is an explanation of the direction of induced magnetic anisotropy imparted to the magnetic metal ribbon of the same torque sensor. Figure 2 is a detection characteristic diagram of the rib torque by the same torque sensor, Figure 3 is a schematic configuration diagram of the torque sensor at the same torque,
Figures (b) and (C) are explanatory diagrams of the direction of the magnetic metal ribbon of the same torque sensor, Figure 5 is a principle diagram of a non-contact type torque sensor, and Figure 6 ( a
> and (b) are strategic configuration diagrams of conventional torque sensors, respectively. 21.31...Torque transmission shaft, 221.222.32
1-324...Magnetic metal ribbon, 231.232.33
I~334...Detection magnetic core, 24s, 242.341
~344...excitation winding, 25+, 252.351~
354...Detection winding. Applicant's agent Patent attorney Takehiko Suzue Figure 1 (b) (C) Figure 2 Figure 3 〇 9 27'L
↓Go to Figure 4 (b) (c) Figure 5

Claims (1)

[Claims] A torque sensor in which 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 shaft, A plurality of magnetic metal thin strips are partially fixed in pairs or multiple pairs on the same circumference in the circumferential direction of the torque transmission shaft, and the magnetic metal thin strips forming pairs are fixed in different directions with respect to the circumferential direction. In addition to imparting magnetic anisotropy, paired detection magnetic cores are disposed close to the paired magnetic metal thin strips, and detection windings attached to these detection cores are differentially connected. A torque sensor featuring: