JPS59208431A - Torque detecting device - Google Patents

Abstract

PURPOSE:To make it possible to detect small torque highly accurately and to provide strength against large torque, by providing a tubular body, which is linked by a coupling structure that is provided with play and engaged and comprises a magnetic body that is fixed to both shafts; and covering the outer surface of the coupling part of a shaft to be measured. CONSTITUTION:Torque is applied to a shaft 10 to be measured. When the torque is relatively small, twisting moment acts on a tubular body 15 and a small diameter part 16b of a torsion bar 16, because engaging pawls 13 and 14 of two shafts 11 and 12 have plays. At this time, the twisting strength of said tubular body 15 and the small diameter part 16a of the torsion bar 16 are low. Therefore, the twisting amount is largely fluctuated with respect to the minute torque fluctuation, and the magnetostriction quantity yielded in the tubular body 15 is largely fluctuated. When relatively large torque is applied, the twisting moment also acts on the shafts 11 and 12, and the fluctuating rate of the twisting quantity of the tubular body 15 with respect to the fluctuation quantity becomes small.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a torque detection device using a magnetostrictive effect.

(Prior art and its problems) As a conventional torque detection device, for example, the
Various structures have been known in the past, such as one having a criss-cross core as shown in Japanese Patent No. 4985.

1 and 2 are diagrams showing the configuration of a detection section of a magnetostrictive torque detection device having a criss-cross core, with FIG. 1 being a front view thereof, and FIG. It is a cross-sectional view.

This 1~lux detection device is! 1. A U-shaped excitation core 2 is placed on the outside of the measured shaft 1 formed of a bamboo body and parallel to the axis, and its legs 2a, 2
b, excitation coils 3a, 3 connected in series with each other;
Further, a U-shaped detection core 4 is similarly arranged perpendicular to the excitation core 2, and detection coils 5 connected in series are disposed on both legs 4a and 4b of the U-shaped detection core 4.
a, 5 wires, thereby exciting coils 3a, 3
The measured shaft 1 is alternately magnetized in the axial direction by the magnetomotive force of b, and the magnetic flux magnetostrictive component generated on the measured shaft according to the torque applied to the measured shaft 1 is linked with the detection coils 5a and 5b, and the applied 1 - An induced electromotive force corresponding to the torque is induced in the detection coils 5a and 5b.

However, in the above conventional torque detection device,
Since the shaft to be measured is made of a single round bar, for example, when detecting a relatively large torque such as the engine torque of a car, a shaft to be measured with a large diameter can be used to improve accuracy and strength. However, when detecting a relatively small torque equal to or less than IKam, such as the steering torque of a steering wheel of an automobile, detection accuracy decreases with a shaft to be measured having a large diameter.

Furthermore, if the diameter of the shaft to be measured is reduced in order to detect small torques, the detection accuracy will improve, but the strength will decrease, so when detecting the steering torque of the steering wheel as described above, etc. When a vehicle runs over a vehicle, a large torque (20 km or more) is instantaneously applied, causing problems such as plastic deformation of the shaft to be measured and magnetic distortion remaining on the surface.

(Objective of the Invention) This invention was made in view of the above circumstances, and its purpose is to be able to accurately detect even a small 1 herk, and to detect when a large torque is applied.
It is an object of the present invention to provide a torque detection device that has strength comparable to that and is highly mass-producible.

(Structure of the Invention) In order to achieve the above-mentioned object, the present invention 5e comprises two shafts connected by a joint structure that meshes the shaft to be measured with a play of a predetermined gap, and The device is characterized in that a tubular body made of the measured magnetic material is provided.

(Description of an Embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG. 3 and subsequent drawings.

FIG. 3 is a diagram showing the structure of an embodiment of the 1-lux detection device according to the present invention. In the same figure, the excitation coil J that excites the shaft to be measured and the detection coil that detects the magnetostrictive component of the magnetic flux generated in the shaft to be measured have the same configuration as the conventional example shown in FIG. Therefore, illustration and description will be omitted.

As shown in the figure, in the torque detection device of this embodiment, the shaft to be measured 10 is formed by connecting two cylindrical shafts 11 (first shaft) and 12 (second shaft). A plurality of interlocking pawls 13.14 are provided in the section and protrude in the axial direction, and the interlocking pawls 13.14 are connected to each other by interlocking with each other.

Furthermore, a play of a predetermined gap d is provided between the engaging pawl 13 and the engaging pawl 14.

A tubular body 15 made of a magnetic material is fitted into the connecting portion of the shaft 10 to be measured, covering the outer circumference thereof and having both ends welded and fixed to the outer circumferences of the two shafts 11 and 12, respectively.

Further, a torsion bar 16 having a small diameter portion 16a formed at the connecting portion of the shaft to be measured 10 is inserted into the inside of the shaft to be measured 10, as shown in the vertical cross-sectional view in FIG. 4 and the horizontal cross-sectional view in FIG. has been done. This]--version 16 is
A spline is formed along the axial direction on the outer periphery of the shaft 5-11.12, and the shaft 5-11.12 is inserted into and engaged with the spline formed correspondingly on the inner surface of the shaft 5-11.12.

It should be noted that adhesive is applied or filled to the engaging portions of this torsion bar 16 and the two shafts 11 and 12! A strong bond can be achieved by tightening.

In addition, the above two shafts 11 and 12 and the torsion bar 1
The abrasive material No. 6 may be either magnetic or non-magnetic.

” - In the torque detection device configured as described above, when torque is applied to the shaft 10 to be measured, if this applied torque is relatively small, the two shafts 11 and 12
Since the engaging pawls 13 and 14 have play, the torsional moment is generated between the tubular body 15 and the torsion bar 1.
This will work on the small diameter portion 16a of No.6. In this case, since both the tubular body 15 and the small diameter portion 16a of the torsion bar 16 have low torsional strength, the amount of torsion varies greatly even with minute torque fluctuations, and this causes strain in the tubular body 15. The suspension will change significantly.

On the other hand, when a relatively large torque is applied to the shaft 10 to be measured, the engaging pawls 13 and 14 come into contact with each other, and the torsional moment is generated between the tubular body 15 and the small diameter portion of the hexion bar 16. In addition to 16a, it will also act on axis 11.12. As a result, the strength against torsional moment increases rapidly, the rate of variation in the amount of twist of the tubular body 15 with respect to the amount of variation in torque decreases, and the rate of variation in magnetostriction also decreases.

If the torque when the engaging claws 13 and 14 come into contact is the reference torque T, then as shown in FIG. 6, when a small torque less than the reference torque T is applied, 11
The rate of change in the detection output of the distortion component is large, allowing highly accurate detection.

Further, when a large torque equal to or greater than the reference torque 91 is applied, the rate of change in the detected output of the magnetostrictive component becomes small, but the strength against torsional moments increases due to the connection of the two shafts 11 and 12. However, problems such as plastic deformation of the tubular body 15 and magnetic distortion remaining on the surface do not occur.

Further, since the engaging pawls 13, 14 are formed on two shafts 12, 11 each having a large diameter, the predetermined gap d, which requires precision machining, has high accuracy and is excellent in mass production.

In addition, some conventional torque detection devices have a coating of highly magnetic material formed on a part of the outer periphery of the shaft to be measured by plating. Although there was a risk of peeling and the durability was low, the durability and productivity were improved by the structure in which the magnetic tubular body 15 was fitted and fixed to the outside of the shaft 10 to be measured as in the example described in J. can be done.

In the above embodiment, the configuration of the excitation core and the detection core is criss-cross type = 17, but the shape of each core is not limited to this. Of course, the present invention can also be applied to an annular core as shown in Japanese Patent No. 35-12=147.

(Effects of the Invention) As explained in detail, the torque detection device of the present invention can detect even weak torque fluctuations with high accuracy, and when a large torque is applied. Failures do not occur, performance can be improved in both sensitivity and strength, and productivity is greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a conventional torque detection device, FIG. 2 is a sectional view taken along the line ■-■ in FIG. FIG. 4 is a longitudinal sectional view of the same device, FIG. 5 is a cross-sectional view of the same device, and FIG. 6 is a graph showing the relationship between torque and magnetostrictive component detection output in the same device. 2・・・・・・・・・・・・・・・Excitation core 4
・・・・・・・・・・・・・・・Detection core 10
・・・・・・・・・・・・Measurement axis 11...
・・・・・・・・・・・・First axis 12・・・・・・・・・
...Second shaft 13.14...Matching pawl 15...Tubular body d...
・・・・・・・・・・・・・・・Play 9- Figure 1 Figure 2

Claims (1)

[Claims] (1) A shaft to be measured, which is formed by connecting two shafts by a joint structure that meshes with a predetermined play of a predetermined gap: A magnetic shaft that covers the outer periphery of the connecting portion of the shaft to be measured and is bonded and fixed to both shafts. a tubular body consisting of: an excitation coil disposed outside the tubular body and for alternately magnetizing the tubular body in a certain direction; A torque detection device comprising: a detection coil for outputting a magnetostrictive component.