JPS63210738A - Torque sensor - Google Patents

Abstract

PURPOSE:To improve operation efficiency at the time of manufacture and assembly by mounting a housing so as to cover a magnetic body formed on a cylindrical member, fitting an exciting and a detection coil on the internal surface of the housing, and constituting the iron cores of the coils by using laminate steel plates. CONSTITUTION:The housing body 32 is fitted covering the amorphous magnetic body 20 formed at the center part 18 rotatably together with the member 18. An opening part is bored in the center part of the housing 32 and a lid 46 is constituted so that it is freely opened and closed. Iron cores 60, 62, and 64 formed by laminating steel plates are fitted in a U shape to the reverse surface side of the lid 46 and combined so that their lamination directions cross each other at right angles. The iron cores are raised vertically and partially to constitute leg parts constituting magnetic electrodes, whose tip end surfaces 60b, 62b, and 64b are curved to the same radius of curvature with the member 18 so that the gap (d) to the surface of the magnetic body; 20 is uniform over the entire area. Further, the leg part 60a is wound with an exciting coil 70 and the leg parts 62a and 64a are wound with detection coils 72 and 72 rotationally symmetrically. Thus, an excitation frequency is increased to improve detection sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a torque sensor, and more specifically to a torque sensor that measures the torque of a rotating shaft such as a drive shaft or a steering shaft of an automobile.

(Prior Art) Conventionally, so-called indirect torque sensors have been used as this type of torque sensors, which measure torque by detecting the torsion angle of the shaft, but they are unsatisfactory because they cannot measure static torque. Therefore, a so-called direct type torque sensor using the magnetostriction phenomenon has recently been proposed, and an example thereof is the technique described in Japanese Patent Application Laid-Open No. 57-211030.

(Problems to be Solved by the Invention) However, in the above conventional example, since the magnetostrictive magnetic material is directly fixed to the shaft to be measured, it is inevitable that the shaft to be measured is part of the structure of the torque sensor. The disadvantage was that they had to be involved. As a result, when manufacturing or assembling the torque sensor, it is difficult to accurately fix the magnetic material at a predetermined position on the shaft to be measured, for example, a long shaft such as a drive shaft. It is extremely tedious to safely transport or store stuck drive shafts, etc., without damaging the fixed surfaces or letting dust adhere to them until the later stage of the vehicle assembly process, and then assembling them in the designated locations when the vehicle is assembled. Met.

Furthermore, as a result of the measured axis being involved as part of the sensor,
The sensor is not completed unless it is assembled on the shaft, and therefore the gap between the magnetic body and the coil cannot be adjusted until that point.In addition, the shaft to be measured, such as the drive shaft, is not strong enough. Although sufficient consideration has been taken, there are inconveniences such as the need for special adjustment means to adjust the gap because special precision is not required in terms of dimensions, and there are also inconveniences in inventory management, performance management, maintenance, etc. .

Furthermore, a part of the sensor, especially a part that is relatively susceptible to mechanical shock such as the coil, is not configured to be easily removed from the outside, which requires extra consideration during assembly and is also inconvenient in maintenance. There are disadvantages, and the measurement accuracy is also far from sufficient.

Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to fix the magnetic body to a member separate and independent from the shaft to be measured so that it can be freely attached to and detached from the shaft to be measured via the member. The object of the present invention is to propose a torque sensor in which the torque sensor is constructed as a single unit that is structurally separated without being involved in the shaft to be measured, and can be mounted on the shaft to be measured as is after completion.

Furthermore, the magnetic material is fixed to a member separate from the shaft to be measured without involving the shaft, and the fixed surface is covered with a casing to prevent damage during transportation, storage, and assembly. In addition, by completing the torque sensor as a single unit, there is no need for special adjustment means for adjusting the gap between parts, especially between the magnetic body and the coil, and we also propose a torque sensor that further improves measurement accuracy. purpose.

(Means for Solving the Problems) In order to achieve the above object, the torque sensor according to the present invention includes a magnetic material that changes its magnetostrictive characteristics according to the amount of applied torque, and In a torque sensor comprising excitation and detection coils arranged facing each other and detecting changes in magnetostriction, a removable cylindrical member is provided on the shaft to be measured, and the magnetic body is fixed on the cylindrical surface of the removable cylindrical member, Furthermore, a housing is rotatably attached to the outer periphery of the cylindrical member so as to cover the surface to which the magnetic material is fixed, and the coil is attached to the inner surface of the housing, and each core of the coil is made of a laminated steel plate. It is composed of

(Function) A cylindrical member configured separately from the shaft to be measured is provided, a magnetic material is fixed thereto, and a casing is rotatably provided on the outer periphery of the cylindrical member, and a coil is attached inside the cylindrical member. Configured. Since the cylindrical member and the shaft to be measured are spline-coupled, the rotational motion of the shaft to be measured is directly transmitted to the cylindrical member, and the resulting magnetostriction change in the magnetic body is induced by a coil in a stationary position. It is detected as an electromotive force and the direction of rotation and amount of torque are measured. Since the sensor is completed separately from the shaft to be measured, work efficiency during manufacturing, assembly, and maintenance is greatly improved.

(Example) Hereinafter, an example of a torque sensor according to the present invention will be described with reference to the accompanying drawings. Figure 1 is a top view of the state in which it is attached to the shaft to be measured, Figure 2 is a sectional view of it along the line ■-■, Figure 3 is a cross-sectional view of Figure 2 along the line ■-■, and Figure 4 is the view of Figure 1. It is a sectional view taken along the line IV-IV.

In the figure, the reference numeral 10 indicates the above-mentioned cylindrical member.

The cylindrical member 10 is approximately cylindrical, and has an inner hole 14 (FIG. 8) whose diameter is slightly larger than the outer diameter of the shaft 12 to be measured, which is bored through the entire length thereof. The shaft 12 can be inserted therein and secured as described below.

Step portions 16 are provided at appropriate left and right positions near the center of the cylindrical member 10.
A cylindrical portion 18 with a relatively small diameter is formed between the step portions 16, 16, and an amorphous magnetic material 20 is plated thereon as the above-mentioned magnetostrictive magnetic material using the step portion as a positioning guide. It is fixed by means such as. On the other hand, the diameter between the stepped portions 16, 16 and the end portions is relatively large, and boss portions 22, 22 are formed there. As clearly shown in FIG. 3 or 8, a spline groove 24.24 is formed on the inner wall surface of the boss portion 22.22, and a male spline shaft portion 26 is also formed at a corresponding position on the shaft 12 to be measured. .26 is engraved so that when the shaft 12 to be measured is inserted into the cylindrical member, the two mesh with each other and are firmly connected. In addition, when manufacturing the spline groove 24 and the spline shaft portion 26, dimensional tolerances are strictly controlled, and the shaft to be measured 12 is attached to the cylindrical member 1.
It is press-fitted within the inner hole 14 of 0 to the extent that no mechanical deformation occurs. As a result, the shaft 12 to be measured and the cylindrical member 10 are connected without slipping, and the torque applied to the shaft 12 to be measured is accurately transmitted to the cylindrical member 10. Incidentally, in order to prevent the cylindrical member 10 from moving in the axial direction, circlips 28, 28 are fitted on the shaft 12 to be measured as the aforementioned locking means.

Thus, the casing 32 is fitted onto the outer peripheral side of the cylindrical member 10. The casing 32 is fitted via bearings 34 and 34 provided on the outer peripheral surface of the boss portion 22 of the cylindrical member 10, so that it is rotatable independently of the cylindrical member 10. Even if the measured shaft 12 rotates, it is possible to maintain a stationary position without being affected by the rotation. Furthermore, the symbol 36.36 indicates the oil seal, and the symbol 38°3 indicates the oil seal.
Reference numeral 8 indicates a backing, and reference numerals 40, 40 and 41, 41 indicate rings fitted through bearings to prevent movement of the casing 32.

As shown in FIG. 1, the housing 32 has a roughly drum-like shape, and has a relatively small diameter near the center to reduce weight, and partially protrudes outward near the center. The protrusion 42
is formed. The protrusion 42 has an opening 44 (FIG. 8).
is formed, and the opening 44 is configured to be openable and closable with a lid 46. As shown in FIG. 1, the M46 has a generally rectangular shape, has ears 48 protruding from three places, and can be freely attached to the casing 32 with screws 52 through screw holes 50 formed there. . As clearly shown in FIG. 6, the back side of the lid 46 is provided with a groove 54 around the same circumference, and an O-ring 56 is disposed therein to airtightly seal the gap between the lid 46 and the casing 32.
(O-rings are not shown in FIGS. 5 and 6). As shown in the figure, the mounting surface of the lid 46 is formed flat and the three screw holes 50 are also located on the same plane, making assembly easy.

On the back side of the lid 46, iron cores 60, 62, and 64, which are made of three laminated steel plates such as silicon copper plates, are attached via stays 66 and screws 68 so as to have a U-shape in the top view of FIG. attached. In this case, the steel plates of each core are assembled and attached so that the stacking directions intersect at right angles, as shown in FIG. Each of the three iron cores has legs 60a, 62a, and 64a, a portion of which stands up vertically to form magnetic poles, and the tip surfaces 60b, 62b, and 64b of each leg are an amorphous fixing surface. They are spaced apart by a predetermined distance and are curved with the same radius of curvature as the cylindrical portion 18 of the cylindrical member serving as the fixing surface, so that the respective tip surfaces have a gap "d" (the second (Fig. 4) is made uniform. A coil is wound around each leg, and the arrangement thereof will be explained with reference to FIG. Two detection coils 72, 72 are wound rotationally symmetrically around the legs 62a, 64.a located at the center. Here, the excitation coil 70 and the detection coils 72, 72 have a magnetic flux path connecting them in a direction of ±45 degrees with respect to the axial direction of the shaft 12 to be measured, that is, the compressive stress and tensile stress caused by the applied torque are maximum. It is arranged so that it coincides with the direction. Note that the amorphous magnetic material 2 fixed to the cylindrical member lO
Regarding 0, uniaxial magnetic anisotropy is given in advance in the same direction. By the way, in this type of torque sensor, the detection sensitivity improves as the excitation frequency of the excitation coil increases, but in that case, if each iron core is made of one iron material, the iron will increase in proportion to the square of the frequency. There is a disadvantage that the eddy current product during loss increases. In the case of the torque sensor according to the present invention, as described above, the iron core is manufactured from laminated steel plates and the laminated directions of the steel plates are combined so that they are perpendicular to each other, so this problem can be avoided and the detection sensitivity can be improved by increasing the excitation frequency. It is possible.

The l [46 has a small protrusion 80 that gradually protrudes outward near the position where the two detection coils 72, 72 are attached, and the small protrusion 80 is provided near the end. It opens to form a small opening 82, into which a grommet 84 is inserted. A harness 86 in which coil signal wires are bundled is passed through the grommet 84 from the outside, and after the harness 86 passes through the grommet 84, each signal wire is branched and connected to each coil. As shown in FIG. 7, a clamper 88 is provided in the immediate vicinity of this branching position. The clamper 88
has a roughly Ω-shape, and its upper annular portion grips the harness 86, and its lower portion is fixed onto the inner wall surface of the small protrusion 80 of the lid via a claw 90. Therefore, since the harness 86 is fixed to the clamper 88, there is no problem such as disconnection of the signal line connected to the coil even if an unexpected pulling force is applied from the outside.

Further, the grommet 84 is provided with protrusions at appropriate positions to prevent it from coming off through the small opening 82, and resin is filled between the protrusions to airtightly seal the inside of the casing (not shown). .

Next, the operation of attaching the torque sensor according to the present invention to the shaft to be measured and the detection operation after attachment will be explained.

First, to explain how to attach the shaft 12 to be measured with reference to FIG. 8, with the lid 46 removed, the shaft 12 to be measured is inserted into the inner hole 14 of the cylindrical member 10 in the casing 32 by attaching the spline to the shaft 12 to be measured. The shaft portion 26.26 and the spline groove 24.24 on the inner wall surface of the boss portion 22 of the cylindrical member are aligned and inserted, and after insertion, the circlip 28.28 is fitted around the tube. After that, the box 32
A torque sensor is completed by attaching a lid 46 with a coil attached to the back side from the outside. After this, the box 32
is fixed with bolts and nuts to a bracket 93 protruding from a fixed part of the vehicle body or the like via a fixed wing 91 and a stay 92 provided on the same circumference.

Next, the detection operation will be explained with reference to FIGS. 9 and 10. After the excitation coil 70 is energized by the AC power source 94 and excited, when a predetermined amount of torque is applied to the shaft 12 to be measured, the torque is proportional to the torque. The amount of torque is applied to the spline shaft 26.2
6 and the spline grooves 24, 24 to the cylindrical member 10, and magnetostriction caused by compressive stress and tensile stress is generated in the direction indicated by 96 on the amorphous magnetic material 20 fixed therein, as is known in the art. . The change in magnetic permeability due to the magnetostriction is detected by two detection coils 72.7 arranged relative to the excitation coil 70 so as to form a magnetic flux path in the same direction.
2 and output as an induced electromotive voltage. After the output is extracted differentially, it is appropriately amplified by the amplifier circuit 98 and rectified by the rectifier circuit 100. The phase of the rectified output indicates the direction of torque application, and the output value of the stationery indicates the amount of applied torque. Become. Note that since the detection output is taken out through differential connection, even if the shaft 12 to be measured is a ferromagnetic material, it will not be affected by it.

As a result of the torque sensor according to the present invention being completed as a single unit without involving the shaft to be measured, it is only necessary to attach it to the measuring shaft as is in the appropriate process during vehicle assembly, and the amorphous magnetic material 20 is also attached to the drive shaft. The work efficiency is improved in that it only needs to be fixed on the cylindrical member 10, which is much easier to handle because it is shorter than the shaft to be measured, and furthermore, the surface on which the magnetic material is fixed is covered with the casing 32. As a result, work efficiency is improved in that transportation, storage, and assembly require less consideration for damage or dust adhesion. Furthermore, since the coil is attached to the back surface of the lid 46, which can be freely removed from the outside, assembly and maintenance operations are facilitated.

Furthermore, during manufacturing, the press-fitting position of the bearing 34, the casing 32
146, iron cores 60, 62, 64, etc., is not so difficult because the target parts are limited to the necessary minimum. Coupled with the effect of
(Fig. 4) can always be kept at a uniform value, so there is no need for special adjustment means for gap adjustment, and it is possible to reduce size, weight, and cost, and also to reduce the variation in dimensions between sensors. , it is possible to reduce the resulting output variations.

Although amorphous magnetic material was used as the magnetic material in the above embodiments, the material is not limited to this, and any material having magnetostrictive properties may be used.

(Effects of the Invention) The present invention is characterized in that a magnetic material is fixed on a cylindrical member that is independent of the shaft to be measured and can be fixed there through a spline coupling means, and a casing is rotatably attached to the outer periphery of the cylindrical member. Since the fixing surface is covered and the coil is attached to its inner surface, the magnetic material fixing work can be done on a cylindrical member that is much shorter than the shaft to be measured, which greatly improves work efficiency. It has the advantage of improving work efficiency, especially in that the heat capacity during fixing work is small. Furthermore, during assembly into a vehicle, during transportation and storage before and after that, the fixed surface is covered and protected by a casing, reducing the burden of consideration for damage to the fixed surface, dust adhesion, etc. It also has the advantage of improving work efficiency. Furthermore, since it is completed as a single unit, it has the advantage of facilitating parts management and inventory management.

Furthermore, by completing the torque sensor as a single unit with a circular cylindrical member and a casing, we have made it easier to manage the dimensional accuracy of the component parts, and as a result, we have improved the size of the gap between the parts, especially between the fixed surface and the end surface of the coil leg. This has the advantage of being easier to manage and reducing variations in output from sensor to sensor.

[Brief explanation of the drawing]

Fig. 1 is a plan view of the torque sensor according to the present invention mounted on a shaft to be measured, Fig. 2 is a sectional view thereof along the line ■-■, and Fig.
The figure is a sectional view taken along the line ■-■ in Figure 2, and Figure 4 is a cross-sectional view taken along the line IV-IV in Figure 1.
5 is a plan view of the back surface of the lid of the enclosure, FIG. 6 is an explanatory perspective view of the back surface of the lid, FIG. 7 is an explanatory perspective view showing the clamper of the harness, and FIG. 8 is a plan view of the back surface of the lid of the enclosure. FIG. 9 is a diagram showing the detection operation of the torque sensor according to the present invention, and FIG. 10 is an explanatory block diagram showing the configuration of the detection circuit of the sensor. 10... Cylindrical member, 12... Axis to be measured, 20...
Amorphous magnetic material, 22... Boss portion, 24... Spline groove, 26... Spline shaft portion, 28... Circlip, 32... Enclosure, 46... Lid, 56...
・0 ring, 6Q, 62.64... iron core, 60a, 6
2a, 64a... leg, 60 b, 62 b,
62 c... Tip surface, 70... Excitation coil, 72
...Detection coil, 84...Grommet, 86...
Harness, 88... Clamper Patent applicant Honda Motor Co., Ltd. Figure 6 Figure 9 Figure 10

Claims (4)

[Claims] (1) A torque sensor consisting of a magnetic material that changes its magnetostrictive characteristics according to the amount of torque applied, and an excitation and detection coil that is placed opposite to the magnetic material and detects changes in the magnetostriction, A removable cylindrical member is provided on the shaft to be measured, the magnetic material is fixed on the cylindrical surface of the cylindrical member, and a casing is rotatably attached to the outer periphery of the cylindrical member so as to cover the surface to which the magnetic material is fixed. A torque sensor, wherein the coil is attached to the inner surface of the torque sensor, and each core of the coil is made of a laminated steel plate. (2) The torque sensor according to claim 1, wherein the iron cores are assembled so that the lamination directions of the steel plates are orthogonal to each other. (3) The torque sensor according to claim 1, wherein the excitation coil has legs constituting magnetic poles having different lengths from those of the detection coil. (4) The torque sensor according to claim 3, wherein the excitation coil and the detection coil have a radius of curvature equal to that of the magnetic body fixing surface with which the tip end surface of the leg portion faces.