JPS6044840A - Torque detecting device - Google Patents

Abstract

PURPOSE:To measure the torque of a driven shaft without providing rotation dependence of the driven shaft, by imparting a magnetic field in the circumferential direction of the driven shaft, and detecting the component of magnetic flux in the axial direction by a detecting coil. CONSTITUTION:A magnetic field is imparted in the circumferential direction of a driven shaft 1 by exciting devices 3a and 3b. A thin, ribbon shaped magnetic layer 2 is fixed to the outer surface of the driven shaft 1. When torque is applied to the driven shaft 1, magnetic change is yielded in the magnetic layer 2. Then, unbalance is yielded in the magnetic resistance in the magnetic layer 2, and the magnetic flux is changed in the direction having an angle, which is proportional to the torque. The component of the magnetic flux in the axial direction is detected by a detecting coil 9, and the torque, which is applied to the driven shaft 1, is measured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a torque detection device that non-contactly measures the shaft torque of a passive shaft such as a rotating shaft.

[Prior art] Conventionally, the method of measuring shaft torque of a passive shaft, such as a rotating shaft, is to attach a strain gauge to the rotating shaft and detect the torque by detecting the change in resistance value of the strain gauge due to twisting of the shaft due to torque. There is a method in which an intermediate shaft with a known Young's modulus is inserted between the drive side and the load side, and the torsion of the intermediate shaft is detected as a phase difference. There is a method that utilizes the so-called magnetostrictive effect in which magnetic permeability changes.

The method of attaching the strain gauge to the rotating shaft has the disadvantage that accuracy is affected by how well the strain gauge is attached, and in addition, it is necessary to attach a slip ring, telemeter, etc. to take out the output signal.
The device becomes larger. In addition, there is a drawback that when rotating at high speeds and operating for long periods of time, the electrical resistance value of the slip ring changes and noise is likely to occur. The method of detecting the phase difference due to the torsion of the intermediate shaft requires a complicated electric circuit and is therefore expensive, and has the disadvantage that it is difficult to detect both high-speed rotation and low-speed rotation of the rotary shaft. The method of utilizing the magnetostrictive effect using a magnetic material shaft has the advantage that an actual shaft can be used.

However, on the other hand, most of the attention is paid to the strength of ordinary shafts, and not much consideration is given to the magnetic properties.
Magnetically it is extremely non-uniform.

Therefore, due to the magnetic non-uniformity of this axis, the output has rotation angle dependence, that is, the output drifts as the axis rotates.
In other words, it has the disadvantage that the output varies depending on the rotation angle. However, this output drift, that is, output fluctuation, can be corrected by providing a plurality of detectors around the axis, but this increases the complexity of the structure and is not a preferable method.

[Summary of the Invention] This invention was made to eliminate the drawbacks of the conventional method as described above, and uses an exciting device to apply a magnetic field in the circumferential direction of the passive shaft, thereby applying torque to the passive shaft. The axial torque of the passive shaft is detected by detecting the axial component of the magnetic flux generated when the magnetic flux is applied by a detection coil wound close to the passive shaft.

[Embodiments of the Invention] - Fig. 1 is a perspective view showing an embodiment of the present invention, Fig. 2 is a longitudinal sectional view thereof, and Fig. 3 is a transverse sectional view thereof.

FIG. 4 is an excitation coil connection diagram. In fig.

(1) is a passive shaft such as a rotating shaft (hereinafter referred to as a rotating shaft), which is made of a non-magnetic material such as stainless steel and has sufficient mechanical strength to withstand torque. (2
) is a thin ribbon-shaped magnetic layer, which is firmly fixed to the outer periphery of the rotating shaft +11 with an adhesive or the like. This magnetic layer (2) is preferably soft magnetic and has high magnetostriction characteristics, and is preferably an amorphous metal. This is because amorphous metals have high magnetostrictive properties, excellent mechanical strength, and little change in properties due to temperature. Also, by performing strain relief annealing, it is possible to produce a material with more uniform magnetic properties. (3a) is the yoke (4a)
and an excitation coil (5a) t (Sa).

(6b) is a yoke (4b) and an exciting coil (sb),
(sb). York (4
a) and (4b) are two magnetic poles (7a) and (8a), respectively, which are closely opposed to the outer peripheral surface of the rotating shaft fl) as shown in the figure.
, (711X81)), and one yoke (4a) has the above-mentioned magnetic pole (7a).
, (8a) are wound with two excitation coils (5a) and (6a) having the same number of turns, and the other yoke (
Similarly for 4b), the above magnetic poles (7'b) and (8'b)
Two excitation coils (5b) with the same number of turns across the
9 (6b) is wound. (9) is the above yoke (
4a) and (4b), has the same central axis in the long sleeve direction as the 9th rotating shaft fi+, and is wound around the rotating shaft +1) with a predetermined gap near the outer circumferential surface of the 9th rotating shaft +13. Brush with a coil.

Now, the above excitation coil (5a) I (6a) l (
51:+), (6b> are all connected in parallel to the constant current AC power supply members in the same direction as shown in Fig. 4. Therefore, the magnetic flux passing through the toroidal yoke (4a) is caused by the excitation coil (5a), ( Sa) by magnetic pole (7a) t
(8a) are generated in opposite directions, and this magnetic flux is transmitted through the magnetic poles (7a) and (8a) to the rotating shaft (1).
) is guided to the magnetic layer (2) fixed to the outer peripheral surface of the magnetic layer (2), thus forming two closed loop magnetic paths as shown by dotted lines in FIG. The excitation coil (5t+) is similarly applied to the other toroidal yoke (4b)? The magnetic flux due to (6b) is
It is guided to the magnetic layer (2) to form two closed loop magnetic paths. Therefore, the magnetic layer (2) K is as shown in FIG.

An alternating magnetic field in the circumferential direction as shown by the arrows in FIG. 3 is applied. Note that the above yoke (4a) and excitation coil (5a)
, an alternating magnetic field on the magnetic layer (2) applied by a first excitation device (5a) consisting of (6a), and a second excitation consisting of the yoke (4b) and excitation coils (5b) and (6h). Magnetic layer (2) applied by device (3b)
Each excitation coil (5
Select the winding direction of a) , (6a) t(sb) , and (6b).

In the above configuration, when no torque is applied to the 9-rotation shaft (1), the magnetic layer (2) fixed to the outer peripheral surface of the 9-rotation shaft (1) has uniform magnetic properties. 12
) The magnetic flux generated on the rotation axis (1
) is parallel to the circumferential direction of the detection coil (9
) does not appear, and no electromotive force is generated in the detection coil (9).

However, when torque is applied to the rotating shaft (1), a magnetic change occurs in the magnetic layer (2). That is, in the ±45° direction with respect to the longitudinal center axis of the nine rotational axes, the magnetic permeability increases on the one hand due to tensile stress, and decreases on the other side due to compressive stress. This causes an imbalance in the magnetic resistance within the magnetic layer (2)', and the magnetic flux generated on the magnetic layer (2) is
As shown by the dotted line in the figure, it changes in a direction having an angle proportional to the torque. The tilted magnetic flux can be divided into a circumferential component and an axial component. Detection coil (
This axial component interlinks with the detection coil (9).
) generates an electromotive force. When torque is applied in this way, an axial magnetic flux is generated, and its magnitude is proportional to the additional torque. Therefore, by detecting the magnitude of the electromotive force generated in the detection coil (9), it is possible to rotate 9 times. The torque applied to the shaft (11) can be measured.

In the above embodiment, the excitation device is divided into two toroidal yokes (4a) and (4b).

Four excitation coils (5a), (6a), (5b
), (6b) were used, but Figures 5 and 6
As shown in FIGS. 7 and 7, the number of excitation devices can be reduced to one. That is, the embodiment shown in FIGS. 5 and 6 is an excitation device (3)
the magnetic pole (7).

An example is shown in which one yoke (4) having a yoke (8) and two excitation coils (+5) and (e) are wound around the yoke.

A detection coil (9) is arranged in the cutout portion of the magnetic pole +71 and fsl of the yoke (4). 7th
In the illustrated embodiment, an excitation device (3) consisting of a yoke (4) and an excitation coil (not shown) wound around the yoke (4) is placed close to the outside of the detection coil (9). This is the coil bobby of the detection coil [9].

Furthermore, in each of the above embodiments, an example is shown in which the yoke has a toroidal shape, but since the yoke is used to provide a magnetic path for applying a magnetic field on the rotating shaft, it does not need to be toroidal. Needless to say, the yoke can be omitted if other magnetic path providing means are available. Further, in each of the embodiments, a case has been described in which two coils are used in the excitation device, but it goes without saying that in principle, it is also possible to use one excitation coil.

Furthermore, in the above description, a case has been described in which the one-rotation shaft is made of a non-magnetic material and a magnetic layer is fixed to the outer peripheral surface.

Needless to say, the intended purpose can be achieved if not only the rotating shaft itself but also at least the outer peripheral surface of the rotating shaft is made of magnetic material. Further, in the above description, the case where the passive shaft is a rotary shaft has been described, but it is not limited to nine rotary shafts.

[Effects of the Invention] As described above, according to the present invention, a circumferential magnetic field is applied to the surface of a passive shaft whose outer peripheral surface is made of a magnetic material, and the axial magnetic flux component generated when torque is applied is is configured to be detected by the electromotive force of a detection coil that has the same central axis as the passive shaft and is wound rotationally symmetrically close to the outer circumference of the shaft, so there is no dependence on the rotation angle of the passive shaft. If it can be detected, five effects can be obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing one embodiment of the invention. 2 is a longitudinal sectional view thereof, FIG. 3 is a lateral sectional view, FIG. 4 is an electric circuit diagram, and FIGS. 5, 6, and 7 are diagrams showing other embodiments of the present invention. In Figure 9, (1) is a passive shaft such as a rotating shaft, (2) is a magnetic layer, (31, (3a). (3b) is an excitation device * t4g, (4a) t (4b)
) is yoke * (5) t (5a). (51)), (6) I (sa), (sb)
is the excited carp/l' I (719 (7a)? (7b
) e(811(8a) I (8b) is the magnetic pole, (9)
is a detection coil, and ON is a constant current AC power supply. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Masuo Oiwa (and 2 others) Figure 4 Figure 5 Figure 7 Figure 6

Claims (5)

[Claims] (1) An excitation device that generates a circumferential magnetic flux on the surface of a passive shaft, at least the outer peripheral surface of which is made of a magnetic material. It is wound around the passive shaft with a predetermined gap therebetween. A torque detection device comprising a detection coil that derives an output according to an axial component of the magnetic flux generated when torque is applied to the passive shaft. (2) The torque detection device according to claim 1, wherein the outer peripheral surface of the passive shaft is made of soft magnetic amorphous metal. (3) The torque detection device according to claim 1, wherein the excitation device comprises a yoke having magnetic poles that closely oppose the outer peripheral surface of the passive shaft, and an excitation coil wound around the yoke. (4) The torque detection device according to claim 1, characterized in that an excitation device is disposed close to both sides of the detection coil in the axial direction of the passive shaft. (5) The torque detection device according to claim 1, characterized in that an excitation device is disposed close to the outside of the detection coil.