JPH0678953B2 - Magnetostrictive torque sensor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetostrictive torque sensor, preferably a magnetostrictive torque sensor for measuring torque acting on a shaft by detecting twist of a power transmission shaft of an automobile. The present invention relates to a torque sensor.

[Conventional technology]

In recent years, as a four-wheel drive vehicle, a full-time four-wheel drive vehicle having a mechanism that absorbs a difference in rotational speed between front wheels and rear wheels according to a difference in turning radius, that is, a center differential mechanism has been developed. However, since this center differential mechanism has a function of distributing the torques of the front wheels and the rear wheels in an equal ratio, the driving force transmission limit should be balanced with the lower value of the driving force of the front wheels or the rear wheels. Becomes For example, if one of the front wheels runs idle, the driving energy escapes there, and the driving force of the rear wheels becomes extremely small. For this reason, when a large driving force is generated, for example, during acceleration, the driving force cannot be sufficiently transmitted to the road surface, and it appears as a phenomenon such as slip (idling) of the front wheels or the rear wheels.

In order to prevent such adverse effects, conventionally, a lock mechanism has been provided for directly connecting the power transmission between the front wheels and the rear wheels without passing through the center differential, which requires a large driving force for acceleration or traveling on rough roads. When doing so, the center differential mechanism was manually locked and manually unlocked during normal running that does not require a large driving force.

However, when the vehicle is traveling with the center differential mechanism locked, when the cornering radius is small and the turning radius is small, the rotation speed on the front wheel side becomes too high compared to the rotation speed on the rear wheel side, resulting in negative torque on the front wheel side. Occurs, and a tight corner braking phenomenon occurs in which the brakes are applied only to the front wheels. Due to this phenomenon, when the vehicle speed is high and the centrifugal force due to turning is large, the tire skids in the centrifugal direction, and the difference in the number of rotations of the front and rear wheels is absorbed by the slip of the tire. Had a problem of adversely affecting.

In this way, when traveling with the center differential mechanism locked, a tight corner braking phenomenon occurs, but in order to reliably avoid this, the torque acting on the drive wheels is constantly monitored, and for example, negative torque is applied. In the case of occurrence of the torque, it is necessary to automatically unlock the center differential mechanism. Therefore, it is necessary to accurately measure the torque acting on the drive shaft.

Conventionally, a magnetostrictive torque sensor has been used to measure the torque acting on a torque transmission shaft or the like. this is,
A torque transmission shaft made of a ferromagnetic material is provided with a magnetizing coil in the circumferential direction and a detecting coil in the longitudinal direction of the shaft, and a high frequency current is supplied to the magnetizing coil to alternately magnetize the shaft in the longitudinal direction. The change in the magnetic flux in the circumferential direction that occurs in the shaft when is applied is converted into a voltage by the detection coil and taken out. However, when the shaft to be measured rotates, the magnetic characteristics of the shaft are non-uniform, which causes a problem that the output is disturbed. To solve this,
A method of increasing the number of detection coils is disclosed in Japanese Patent Laid-Open No. 53-77572.

This will be described with reference to FIGS. 10 to 12. In FIG. 10, the torque sensor 61 is mounted on the torque transmission shaft 63 in the transmission 62 via a bearing 64. As shown in FIG. 11, the torque sensor 61 comprises an exciting coil assembly 65 and detection coil assemblies 66 and 67 arranged on both sides of the exciting coil assembly 65.
65, 66, 67 are provided with a ring-shaped portion 68 and a plurality of cores 69, 69, ... Which extend from the ring-shaped portion 68 in the radial direction, and these coil assemblies 65, 66, 67 mount the torque transmission shaft 63. The plurality of cores 69, 6 when encircled and placed
The numbers 9, ... Are close to the outer peripheral surface of the torque transmission shaft 63. Furthermore, the plurality of cores 69, 69 of the coil assemblies 65, 66, 67, ...
The electric windings 70, 70, ..., 71, 71, ... and
72, 72 ... are provided, and as shown in FIG. 12, the electric windings 70, 70, ... Of one coil assembly 65 form the primary winding of the torque sensor 61, and the primary winding is a central tap. It is considered as a serial connection with the grounded. The electric windings 71, 71, ... and 72, 72 ... of the other coil assembly 66, 67 are connected in series to form a secondary winding, and both ends thereof are joined to the subtracting amplifier 75 in the signal processing circuit 73. There is. The subtraction amplifier 75 supplies an output signal relating to the torque of the transmission shaft 63 to the detection circuit 76, passes the filter circuit 77, and displays the torque in the torque indicating device 78.

In the torque sensor disclosed in Japanese Patent Laid-Open No. 59-5930, four detection cores 81a, 81b, 81c and 81d are arranged in parallel with the torque transmission shaft 80 as shown in FIG. The excitation core 83 is arranged at the corner of the base 82, the excitation core 83 is provided at the center of the rectangular base 82, and the tip of the excitation core 83 is arranged at right angles to the torque transmission shaft 80. Are arranged at an angle of 45 degrees up, down, left and right with respect to the torque transmission axis.

The torque detection method will be described with reference to FIGS. 14 and 15. When a high frequency current is passed through the coil e of the exciting core 83, the transmission shaft 80 is provided between the exciting core 83 and each of the detecting cores 81a, 81b, 81c and 81d. A closed loop of the magnetic field is formed via. For example, when the tip of the excitation core 83 has the N pole, the detection core 81
The tip portions of a, 81b, 81c, and 81d become S poles, and a magnetic flux flow in the direction of the arrow in the figure is generated.
Electromotive force is generated on the coils a, 81b, 81c, 81d. At this time, the coils a, b, c, d of the four detection cores are adjacent to each other, as shown in FIG. 14, because the windings of the coils of the adjacent detection cores are opposite to each other. The electromotive forces generated in the coils a, b, c, d have different polarities.

In this state, when the right rotation torque is applied to the right side of the transmission shaft 80 and the left rotation torque T is applied to the left side of the transmission shaft 80, the transmission shaft 80 is rotated about the axis of the transmission shaft 80 at a right angle of 45 degrees. Tensile stress occurs at an angle, compressive stress occurs at an angle of 45 degrees to the left, and permeability increases with tensile stress and decreases with compressive stress. Therefore, as shown in the figure, the strength of the magnetic flux flowing through the coils a and c decreases, and the strength of the magnetic flux flowing through the coils b and d increases. The output voltage generated in each coil a, b, c, d is as shown in FIG. 15 (a). By adding these output voltages in the signal processing circuit, the same figure (b) is shown.
The torque signal is obtained as follows.

[Problems to be solved by the invention]

In the example shown in JP-A-53-77572 of the above conventional torque sensor, in order to accurately position the sensor and the transmission shaft, the bearing is passed through the shaft and then assembled, There is a problem that the number of assembling steps is increased and it is difficult to assemble, and it takes time to wind the winding process due to the structure that each winding has a winding in the inner radial direction on the ring-shaped magnetic core assembly. With poor sex,
There is a problem in that the number of poles cannot be increased because the size is limited to wind a predetermined number of turns, and the size becomes large in the radial direction.

Further, the magnetostrictive torque sensor has hysteresis due to the property of using magnetism. This can be canceled by alternating-current excitation so that the shaft is magnetized to the saturation region and then inversely magnetized, but in the example shown in Japanese Patent Laid-Open No. 59-5930, only one exciting coil is provided. However, there is a problem that an exciting circuit that generates a large current and a winding that withstands the current are required to generate a magnetic flux sufficient to cancel the hysteresis. By applying plating or amorphous processing to the shaft, it is possible to cancel the hysteresis, but this causes problems in the processing method and durability. Further, although this sensor has a relatively small size, since the number of windings increases due to the plurality of detection coils, the number of steps such as addition processing in the signal processing circuit increases, and in order to maintain high accuracy, There is a problem that the signal processing circuit is complicated and expensive. Especially when the transmission shaft rotates at high speed like a vehicle, it is difficult to perform accurate positioning, and in order to keep the gap between the sensor and the transmission shaft constant, it is necessary to improve the dimensional accuracy of the sensor. It is difficult, time consuming and costly.

In addition, the shaft is usually in the case (eg, motor, engine, transmission, transfer).
Therefore, the sensor also has to be assembled in the case, and it is necessary to disassemble the case to take out the sensor when trouble occurs after the assembly is once performed, and it is difficult to repair. In addition, even if it is attached to the case itself, it is necessary to increase the accuracy of the case, making design and processing difficult,
When it is attached to the case, the installation is improved, but
There was a problem that it was difficult to keep the gap constant.

The present invention solves the above-mentioned problems, and it is possible to reduce the size of the sensor, simplify the software with high accuracy, and eliminate the need to increase the dimensional accuracy of the sensor and the torque transmission case more than necessary. Another object of the present invention is to provide a magnetostrictive torque sensor capable of accurately detecting torque by keeping the gap between the transmission shaft and the sensor always constant.

[Means for solving problems]

Therefore, the magnetostrictive torque sensor of the present invention is a magnetostrictive torque sensor that includes one detection element and four excitation elements, and detects the electromotive force generated by the magnetic flux excited by the excitation element by the detection element. The elements are arranged on a shaft, the four exciting elements are arranged on diagonal lines orthogonal to each other with respect to the detecting element, and adjacent exciting elements have mutually opposite magnetic flux directions generated when excited. In addition, the present invention is characterized in that the magnetostrictive torque sensor is fixed by a spring through a mounting hole provided in the case. is there.

[Operation and effect of the invention]

In the present invention, for example, as shown in FIG. 2, when a right rotation torque is applied to the right side of the shaft 5 and a left rotation torque T is applied to the left side of the shaft, the shaft 5 is axially rotated about the axis thereof. On the other hand, a tensile stress is generated at an angle of 45 degrees to the right, a compressive stress is generated in the direction perpendicular to this, and the magnetic permeability is increased by the tensile stress and decreased by the compressive stress. Therefore, as shown in the figure, the strength of the magnetic flux flowing through the exciting magnetic poles 2a and 2c decreases, the strength of the magnetic flux flowing through the exciting magnetic poles 2b and 2d increases, and the electromotive force generated by each magnetic flux is added. Appears in the detection coil 6.

Therefore, according to the present invention, since the number of windings that requires a large number of turns is one pole, the number of turns can be reduced as a whole and the size can be reduced accordingly, and the same size and cross-sectional area of the core can be produced. Compared with the conventional one-pole excitation four-pole detection method, a space can be secured as much as the number of turns can be reduced, and by allocating this space to the increased number of detection coils, a higher output can be obtained.

In addition, since the detection signals are magnetically added and appear in one coil or Hall element as they are, there is no loss of magnetic flux, and the signal processing circuit has a very simple structure, and high-precision measurement is possible, and overall Can significantly reduce costs.

Furthermore, when the exciting coils are connected in parallel, a large amount of magnetic flux is generated with a small amount of current without requiring a large amount of current.
A high-precision sensor is possible without being affected by noise.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing one embodiment of a magnetostrictive torque sensor of the present invention, FIGS. 2 and 3 are views for explaining a torque detecting method of the present invention, and FIG. 4 (a) is a conventional example. FIG. 5 is a diagram showing the detection result according to the present invention, FIG. 6B is a diagram showing the detection result according to the present invention, FIG. 5 is a diagram for explaining the main stress generated when a torsional stress acts on the shaft, and FIG. FIG. 7 is a block diagram of a control system applied to the present invention, FIG. 7 and FIG. 8 are views showing another embodiment of the coil applied to the present invention, and FIG. 9 is a transfer diagram of the magnetostrictive torque sensor of the present invention. It is a longitudinal cross-sectional view attached to the.

In the figure, 1 is a detection pole, 2a, 2b, 2c, 2d are excitation poles, 3 is a top plate, 5 is a torque transmission shaft, 6 is a detection coil, and 7a, 7
Reference numerals b, 7c and 7d denote exciting coils, and 21 denotes a sheet coil.

In FIG. 1, a magnetostrictive torque sensor has one detection pole 1 and four exciting magnetic poles 2a, 2b, 2c, 2d on a diagonal line orthogonal to the detection pole 1 and these detection poles are arranged. 1 and an exciting magnetic pole 2 are press-fitted into a top plate 3. The detection pole 1, the excitation pole 2, and the top plate 3 are manufactured by a laminated structure such as an iron-based material or a silicon steel plate material, or a sintered structure represented by ferrite or the like. The detection pole 1 and the four excitation magnetic poles 2 are parallel to each other, and the tip of the detection pole 1 is arranged so as to be perpendicular to the axial center of the shaft 5, and the tip of each pole is a circular cross section of the shaft 5. It is formed to be parallel to
The tips of the four exciting magnetic poles 2 are arranged at an angle of 45 degrees in the vertical and horizontal directions with respect to the torque transmission shaft. Also, the detection pole 1
The detection coil 6 is wound around the coil, and the exciting coils 7a, 7b, 7c and 7d are wound around the exciting magnetic poles 2a, 2b, 2c and 2d. The exciting coils 7a, 7b, 7c and 7d are connected in series or in parallel and, as shown in FIG. 2, are wound so that the winding directions of the adjacent exciting magnetic poles are opposite to each other. There is. The exciting coils are preferably connected in parallel, and since a large current is not required, the winding can be made thin, and since a large amount of magnetic flux is generated with a small amount of current, it is not affected by noise. A highly accurate sensor becomes possible.

Next, the operation will be described. As shown in FIG. 5, when the right rotation torque is applied to the right side of the shaft 5 and the left rotation torque T is applied to the left side of the shaft 5, the shaft 5 is rotated about the axis of the shaft 5 at an angle of 45 degrees to the right. Tensile stress at an angle of +
σ occurs, a compressive stress −σ occurs at an angle of 45 degrees to the left, and the magnitude of each principal stress is proportional to the distance from the center of the axis. When a torsional stress is applied to the shaft, the magnetic characteristics of the magnetic material change, and in particular the magnetic permeability increases with tensile stress and decreases with compressive stress.

On the other hand, as shown in FIG. 2, exciting coils 7a, 7b, 7c, 7d
When an alternating current is passed through, a closed loop of magnetic flux is formed between the exciting magnetic poles 2a, 2b, 2c, 2d and the detection pole 1 via the shaft 5. At this time, four exciting coils 7a, 7b, 7c, 7d
Since the adjacent coils are wound such that the winding directions of the adjacent coils are opposite to each other, the directions of the magnetic flux generated by the coils are different between the adjacent exciting magnetic poles. For example, when the tip of the exciting magnetic pole 2a is the S pole, the tip of the diagonal exciting magnetic pole 2c is the S pole, and the tips of the other exciting magnetic poles 2b and 2d are the N poles. Since the directions of the adjacent magnetic fluxes are opposite to each other in the flow of the magnetic flux, electromotive forces having different polarities are generated in the detection coil 6 according to the direction of the magnetic flux.

When no torque acts on the shaft 5, the electromotive forces generated by the magnetic fluxes are canceled at the same level, and the output signal becomes zero. From this state, when the right rotation torque is applied to the right side of the shaft 5 and the left rotation torque T is applied to the left side of the shaft, tensile stress is applied around the shaft 5 at an angle of 45 degrees to the right with respect to the axial direction. Occurs, and a compressive stress is generated in the direction perpendicular to this, and the magnetic permeability increases with tensile stress and decreases with compressive stress. Therefore, as shown in the figure, the intensity of the magnetic flux flowing through the exciting magnetic poles 2a and 2c is reduced,
The strength of the magnetic flux flowing through 2b and 2d increases, and the electromotive force generated by each magnetic flux is added and appears in the detection coil 6, so that the output voltage waveform shown in FIG. 3 is obtained.

FIG. 6 is a block diagram of a control system applied to the present invention. The alternating current output from the oscillator 10 and the amplifier 11 is an exciting coil.
Sent to 7a, 7b, 7c, 7d. On the other hand, the electromotive force signal generated in the detection coil 6 is applied to the high pass filter 13 under the control of the phase compensation circuit 12, and then the AC amplifier 15 and the rectifier circuit 1 are provided.
6, output through the smoothing circuit 17, the amplifier circuit 18, and the low-pass filter 19. A temperature compensating circuit including a temperature sensor and its processing circuit, a linearity compensating circuit by a CPU computing unit, and the like may be added.

FIG. 4 (a) shows the measurement results of the conventional 1-pole excitation 4-pole detection method disclosed in Japanese Patent Laid-Open No. 59-5930, and FIG. 4 (b) shows the 4-pole excitation 1-pole detection method according to the present invention. It can be seen that the output characteristics of the present invention are improved as compared with the conventional method.

Next, referring to FIG. 7 and FIG. 8, another embodiment of the exciting coil and the detecting coil applied to the present invention will be described. In this embodiment, a sheet coil 21 is laminated on a core 20 forming the detection pole 1 and the excitation pole 2.
As shown in FIG. 8, the sheet coil 21 is formed by printing the exciting coil 7 and the detecting coil 6 on the front and back sides of the sheet 22 with a photomask pattern and stacking the sheets 22.
The front and back of the coils of each layer are connected by spot welding.

According to this method, since the conductor occupancy of the coil can be increased, the sensor can be further downsized, and the solid strain of the sensor can be eliminated because there is no winding irregularity unlike the winding coil. Further, the equipment such as a winding machine is not required, and the photomask pattern can be formed first, so that the investment effect and the productivity can be improved. Further, by forming the substrate of the signal processing circuit into a sheet, it can be integrated with the sensor to improve the accuracy.

Although the detection element is formed of a coil in the above embodiments, a Hall effect element sensor may be used instead of the coil. The Hall effect sensor uses a semiconductor material, and when a current flows through the Hall effect sensor, the electric field in the semiconductor material changes due to the influence of magnetism to detect the output voltage.

FIG. 9 is a diagram showing a power transmission system of a four-wheel drive vehicle with a center differential equipped with the magnetostrictive torque sensor of the present invention. In the figure, 30 is a transfer gear, A is a center differential mechanism, B is a front differential mechanism, 31 is a ring gear, 32 is a front differential case, 33 is a center differential clutch, 34 is a conical roller bearing, 35 is a first hollow shaft, 36 Is a diff carrier, 37 is a diff pinion, 38 and 39 are side gears, 40 is a second hollow shaft, 41 is a diff carrier, 42 is a diff pinion, 43 and 44 are side gears, 45 is a left front wheel drive shaft, 46 is a drive shaft, 49 is a right front wheel Drive shaft, 50 is a center differential case, 51 is a rear wheel drive ring gear, 52 is a gear, 53 is a drive pinion shaft, 55 is a transfer case, 56 is a mounting hole, 57 is a bolt, 25 is a torque detection device, and 26 is the present invention. Is a magnetostrictive torque sensor, 27 is a sensor assembly, and 28 is a spring.

Generally, in a four-wheel drive vehicle with a center differential, when the engine is mounted on the front side, a driving force transmission mechanism as shown in FIG. 9 is obtained. That is, the rotation of the engine is appropriately shifted through an automatic transmission mechanism (not shown) and transmitted to the front differential case 32 through a ring gear 31 arranged in the transfer 30. During normal running, the center differential clutch 33 is in the released state, and in this state, the rotation of the front differential case 32 is transmitted to the differential carrier 36 of the center differential mechanism A via the first hollow shaft 35, and further the differential pinion 37. To the left and right side gears 38,
Is transmitted to 39. Then, the rotation of the left side gear 38 is the second
It is transmitted to the diff carrier 41 of the front diff mechanism B via the hollow shaft 40, further transmitted from the diff pinion 42 to the left and right side gears 43 and 44, and then transmitted from the left side gear 43 to the left front wheel drive shaft 45 and the right side gear 44. Is transmitted to the right front wheel drive shaft 49 via the drive shaft 46.

On the other hand, the rotation of the right side gear 39 of the center diff mechanism A is transmitted to the center diff case 50 that is splined with the gear, and further transmitted to the drive pinion shaft 53 via the rear wheel drive ring gear 51 and the gear 52. Then, it is transmitted to the left and right rear wheel drive shafts via a propeller shaft and a rear differential device (not shown).

Also, when a large driving force is required on a snowy road, sandy road, etc.,
If the wheels may slip, the center differential clutch 33 is engaged to set the center differential mechanism A.
Lock. In this state, the rotation of the front differential case 32 is directly transmitted to the differential carrier 41 of the front differential mechanism B via the center differential clutch 33, and further transmitted from the differential pinion 42 to the left and right side gears 43, 44 to respectively drive the left and right front wheel drive shafts. It is transmitted to 44 and 49. At the same time, the differential carrier 36 and the left side gear 38 of the center differential device A, which are integrated with the front differential case 32 and the differential carrier 41 via the hollow shafts 35 and 40, respectively, are integrally rotated without differential motion, and further, The rotation is transmitted to the center differential case 50. As a result, rotation at the same speed as that of the front wheel drive differential carrier 41 is transmitted to the rear wheel drive ring gear 51, and the left and right rear wheel drive shafts are driven.

The transfer case 55 of the transfer 30 is provided with a mounting hole 56 at a position facing the drive shaft 46, and the torque detecting device 25 is inserted into the mounting hole 56 and fixed by a bolt 57. The torque detection device 25 is a magnetostrictive torque sensor.
26 is fixed to the sensor assembly 27 with resin by molding,
The sensor assembly 27 is configured to be biased by a spring 28, rubber, or air.

In the above embodiment, the magnetostrictive torque sensor 26
Is molded and fixed in the sensor assembly 27 so that a constant gap is provided with the outer peripheral surface of the transmission shaft 46, and the transmission shaft 46 directly receives the sensor assembly 27, but a bearing is fitted to the transmission shaft 46, The sensor assembly 27 may be mounted on the bearing.

When the magnetostrictive torque sensor is attached to the transfer as described above, the magnetostrictive torque sensor is a floating type with respect to the transmission shaft, so that it is not necessary to raise the accuracy of the case more than necessary, and the assembly is easily performed. be able to. Also, because the torque sensor is fixed to the mold by resin,
The gap between the transmission shaft and the sensor can be easily kept constant, the torque can be accurately detected, and the dimensional accuracy of the sensor can be lowered in order to keep the gap constant.

Also, since the magnetostrictive torque sensor can be installed from the outside of the case, it can be easily installed, and even when trouble occurs, it is not necessary to disassemble the case, and it is easy to repair by replacing only the sensor part. Is possible.

As described above, according to the present invention, since the number of detection coils that require a large number of turns is one pole, the number of turns can be reduced as a whole and the size can be reduced accordingly, and the conditions such as the size and cross-sectional area of the core can be the same. Compared to the conventional 1-pole excitation 4-pole detection method that was produced, a space can be secured as much as the number of turns can be reduced. By allocating this space to the increase of the detection coil, higher output can be achieved. Becomes

In addition, since the detection signal appears in one coil or Hall element, the signal processing circuit has a very simple structure, and highly accurate measurement is possible, resulting in considerable cost reduction as a whole.

Further, when the exciting coils are connected in parallel, a large current is generated without generating a large current, and a large amount of magnetic flux is generated with a small current, so that a highly accurate sensor is possible without being affected by noise.

Further, as compared with the conventional torque sensor of the above-mentioned Japanese Patent Laid-Open No. 53-77572, the axes around which the coil is wound are in the same direction, which makes it easier to wind the coil, and when the sheet coil is adopted, the manufacturing process of the coil is further increased. Can be simplified and workability can be improved.

Furthermore, when the magnetostrictive torque sensor is attached to the case that houses the torque transmission shaft, it is not necessary to raise the precision of the case more than necessary, and the assembly can be done easily. In addition to the above, the dimensional accuracy of the sensor can be lowered.

[Brief description of drawings]

FIG. 1 is a perspective view showing one embodiment of a magnetostrictive torque sensor of the present invention, FIGS. 2 and 3 are views for explaining a torque detecting method of the present invention, and FIG. 4 (a) is a conventional example. FIG. 5 is a diagram showing the detection result according to the present invention, FIG. 6B is a diagram showing the detection result according to the present invention, FIG. 5 is a diagram for explaining the main stress generated when a torsional stress acts on the shaft, and FIG. FIG. 7 is a block diagram of a control system applied to the present invention, FIG. 7 and FIG. 8 are views showing another embodiment of the coil applied to the present invention, and FIG. 9 is a transfer diagram of the magnetostrictive torque sensor of the present invention. Fig. 10, Fig. 11, Fig. 12 and Fig. 12 are views for explaining a conventional torque sensor, and Fig. 13, Fig. 14, Fig. 15 and Fig. 15 explain other conventional torque sensors. FIG. 1 ... Detection pole, 2a, 2b, 2c, 2d ... Excitation pole, 3 ... Top plate, 5 ...
Torque transmission shaft, 6 ... Detection coil, 7a, 7b, 7c, 7d
… Excitation coil, 21… sheet coil. 25 ... Torque detecting device, 26 ... Magnetostrictive torque sensor, 27 ... Sensor assembly, 28
... Spring, (1, 6 ... Sensing element, 2, 7 ... Exciting element).

Claims (8)

[Claims] 1. A magnetostrictive torque sensor comprising one detection element and four excitation elements, wherein the detection element detects an electromotive force generated by a magnetic flux excited by the excitation element.
Two detecting elements are arranged on the shaft, the four exciting elements are arranged on diagonal lines orthogonal to each other about the detecting elements, and the adjacent exciting elements have the directions of the magnetic fluxes generated when excited. A magnetostrictive torque sensor, characterized in that they are formed in opposite directions. 2. The magnetostrictive torque sensor according to claim 1, wherein the detection element is a Hall effect element. 3. The detecting element and the exciting element are composed of a magnetic pole and a coil wound around the magnetic pole, and the coils of adjacent exciting elements are formed by winding in opposite directions to each other. The magnetostrictive torque sensor according to the item. 4. The magnetostrictive torque sensor according to claim 3, wherein the coils of the exciting element are connected in parallel. 5. The magnetostrictive torque sensor according to claim 3, wherein the magnetic poles of the detecting element and the exciting element are formed separately and are press-fitted into the top plate. 6. The magnetostrictive device according to claim 1, wherein the detection element and the excitation element are magnetic poles and sheet coils laminated on the magnetic poles, and the coils are formed by printing on the front and back of the sheet. Torque sensor. 7. The magnetostrictive torque sensor according to claim 1, wherein a diagonal line orthogonal to the detection element is an angle of 45 degrees with respect to the axial direction of the shaft. 8. A magnetostrictive torque sensor comprising one detecting element and four exciting elements, wherein the detecting element detects an electromotive force generated by a magnetic flux excited by the exciting element.
Two detecting elements are arranged on the shaft, the four exciting elements are arranged on diagonal lines orthogonal to each other about the detecting elements, and the adjacent exciting elements have the directions of the magnetic fluxes generated when excited. A magnetostrictive torque sensor, characterized in that the magnetostrictive torque sensor is formed so as to be in mutually opposite directions, and includes a case that internally houses the shaft, and the magnetostrictive torque sensor is fixed by a spring through a mounting hole provided in the case.