JP2020134312A - Magnetostrictive torque detection sensor - Google Patents

Abstract

To provide a magnetostrictive torque detection sensor capable of detecting change in torque generated in a circumferential direction on a side surface of an object to be detected and reducing thickness of the sensor in an axial direction.SOLUTION: A magnetic field generation unit M is arranged close to a side surface of an object S to be detected, and a torque is detected from change in inductance of a magnetic circuit formed between an inner diameter side peripheral wall and an outer diameter side peripheral wall of cores 5a and 5b and a magnetostrictive pattern 4 while a detection coil 5d is energized.SELECTED DRAWING: Figure 2

Description

The present invention relates to a magnetostrictive torque detection sensor.

Conventionally, in a vehicle engine, an industrial motor, or the like, torque measurement is accurately performed along with the rotation speed in order to analyze the operating state of the prime mover. In particular, in vehicle engines, ignition timing control, fuel injection amount control, and shift timing are measured by measuring the torque of the engine itself or various drive systems such as the transmission, propeller shaft, and differential gear that are the driving force transmission mechanism thereof. Alternatively, it is used for gear ratio control and the like, and can be used for various purposes such as improving the fuel efficiency of the vehicle or improving the driving characteristics based on these analysis results. Further, even in an industrial motor, optimum control and diagnostic action of a rotary drive system can be performed based on accurate torque measurement.

The following torque measuring devices are known, for example. That is, a magnetostrictive layer made of a soft high magnetostrictive material is formed on the side surface of the rotating disk that transmits torque, and a first magnetic sensor including an exciting coil and a magnetostrictive detection element is placed at predetermined intervals on the side surface of the magnetostrictive layer in the torque strain generation region. A second magnetic sensor including an exciting coil and a magnetostrictive detection element is arranged to face each other at predetermined intervals on the side surface of the magnetostrictive layer in which torque distortion does not occur, and the first magnetic sensor and the second magnetic sensor are arranged to face each other. There is a device that non-contactly measures the torque transmitted through the rotating disk with the magnetostriction detected by each magnetic sensor by arithmetically processing each detection signal of (Patent Document 1: Japanese Patent Application Laid-Open No. 6-72825). reference).

Special Fair 6-72825 Gazette

In the torque measuring device of Patent Document 1 described above, magnetic sensors including a magnetic coil and a magnetic flux detection element are spaced apart from each other at predetermined intervals on the side surface of a torque distortion generation region of the rotating disk, and are transmitted via the rotating disk. The torque can be detected non-contact with the magnetic strain of the rotating disk detected by the magnetic sensor.
However, since the magnetic sensor is locally arranged on the side surface of the torque distortion generation region of the rotating disk to detect magnetostriction, even if a partial torque change transmitted to the side surface of the rotating disk can be detected, it is uniformly detected over the entire circumference. Can not do it.
Further, since the pair of magnetic sensors are arranged facing each other at predetermined intervals facing the side surface of the rotating disk, the operating point of the magnetostrictive layer becomes unknown in relation to the stop position of the rotating disk, and the location where the magnetostriction occurs becomes unknown. ..
Furthermore, if the number of coils wound around the core is increased, the magnetic sensor becomes larger in the axial direction, making it difficult to assemble it in the device.

The present invention has been made to solve these problems, and an object of the present invention is to be able to uniformly detect the torque generated on the entire side surface of the object to be detected, and to make the sensor thin in the axial direction. It is an object of the present invention to provide a magnetostrictive torque detection sensor capable of achieving this.

The present invention has the following configurations in order to achieve the above object.
A magnetostrictive torque sensor that non-contactly detects changes in torque acting on the axial side surface of a detected object, which is provided in an output unit that is driven and transmitted from a drive source, and is formed around the side surface of the detected object. , A magnetostrictive pattern in which magnetostrictive coating layers made of a magnetostrictive material are formed in a chevron shape at equal intervals, and a magnetic material formed in a U-shaped cross section via a cross-linking portion, with both legs in the radial direction of the object to be detected. A magnetic field generating portion including an annular core arranged along the line and having a leg end surface facing the magnetostrictive pattern and a detection coil provided around the concave groove portion of the annular core is provided. The magnetic field generating portion is detected by energizing the detection coil so that a magnetic circuit is formed between the inner diameter side leg end face and the outer diameter side leg end face and the magnetostrictive pattern facing the annular core. It is characterized by being assembled in close proximity to the body.
As a result, the magnetic field generating part is arranged close to the side surface of the object to be detected, the detection coil is energized, and the torque is detected from the inductance change of the magnetic circuit formed between the annular core and the magnetostrictive pattern arranged opposite to each other. can do. In particular, a detection coil is provided in the concave groove portion of the annular core formed in a U-shaped cross section, and the magnetic flux is concentrated on the magnetic circuit formed by the magnetostrictive pattern facing the inner diameter side leg portion and the outer diameter side leg portion of the annular core. Therefore, the detection sensitivity of the torque acting on the object to be detected is improved. Therefore, the torque generated on the entire side surface of the object to be detected can be uniformly detected, and the sensor can be made thinner in the axial direction.

The first magnetostrictive pattern and the second magnetostrictive pattern formed concentrically on the side surface of the object to be detected are arranged close to each other to form the chevron-shaped magnetostrictive pattern, and each magnetostrictive coating layer forming the magnetostrictive pattern. Is preferably formed so as to have an inclination angle of any of ± 45 ° with respect to the axis of the detected body.
From the above configuration, when torque acts on the side surface of the object to be detected, compressive stress acts in the direction of + 45 ° and tensile stress acts in the direction of -45 °, or tensile stress acts in the direction of + 45 ° and -45. Compressive stress acts in the direction of °. At that time, since the magnetostrictive coating layer is formed so as to have an inclination angle of ± 45 ° with respect to the axis of the object to be detected, the change in magnetic permeability that occurs in the object to be detected is detected by the inductance of the detection coil. It can be detected at the maximum by converting the amount of change into torque.

Further, in the magnetic field generating portion, the first annular core and the second annular core are held side by side from the inside to the outside in the radial direction of the object to be detected, and the first annular core and the first magnetostrictive pattern are held. It is preferable that the second annular core and the second magnetostrictive pattern are arranged to face each other.
In this way, the first annular core and the second annular core provided in the magnetic field generating portion are held side by side from the inside to the outside in the radial direction, the first annular core and the first magnetostrictive pattern are arranged to face each other, and the second annular core is arranged. Since the core and the second magnetostrictive pattern are arranged so as to face each other, a compressive stress acts on the side surface of the object to be detected in one of the circumferential directions in the + 45 ° direction, and a tensile stress acts in the -45 ° direction, or +45. In any case where the tensile stress acts in the direction of ° and the compressive stress acts in the direction of −45 °, the torque change can be detected with high sensitivity.

The magnetostrictive coating layer may be formed by any of metal plating, metal spraying, or adhesion of a metal foil.
As a result, a chevron-like magnetostrictive pattern can be easily formed on the side surface of the object to be detected.

The magnetostrictive coating layer may be formed so as to overlap the side surface of the object to be detected. In this case, the magnetostrictive pattern can be formed without requiring special processing on the object to be detected.

The magnetic strain coating layer may be formed so as to be superimposed on a concave surface portion formed on the side surface of the object to be detected in a thin shape in the axial direction. In this case, since the magnetic generating portion can be arranged as close as possible to the side surface in the axial direction with respect to the object to be detected, leakage of magnetic flux can be reduced and miniaturization of the sensor in the axial direction can be promoted. ..

In each magnetic circuit in which the first annular core and the first magnetostrictive pattern and the second annular core and the second magnetostrictive pattern face each other inside and outside in the radial direction of the object to be detected, the inductances L1 and L2 in each other's magnetic circuits. At least one of the structure or material of each annular core, the area or material of the magnetostrictive pattern, the distance of the magnetostrictive pattern from the torque source on the object to be detected, the number of coil turns or the material is adjusted so that Alternatively, it is preferable that the first detection coil wound around the first annular core and the second detection coil wound around the second annular core are bridge-connected.
As a result, the structure or material of each annular core, the area or material of the magnetostrictive pattern, and the torque generation source on the object to be detected of the magnetostrictive pattern are used so that the inductances L _{1 and} L ₂ detected by the internal and external magnetic circuits are equal to each other. By adjusting at least one of the distance, the number of turns of the coil, and the material, the signal strength can be made the same by canceling the offset amount of the detected output.
Further, when the first detection coil wound around the first annular core and the second detection coil wound around the second annular core are bridge-connected, the positive / negative symmetric torque output is output with the offset portion set to zero. Therefore, a stable output can be obtained that is not easily affected by electromagnetic noise and temperature changes between the coils.

It is possible to provide a magnetostrictive torque detection sensor that can uniformly detect the torque generated over the entire side surface of the object to be detected and can reduce the thickness in the axial direction.

It is a perspective view of the motor with a reducer to which a magnetostrictive torque detection sensor is assembled. It is a perspective view which cut out a part of the output part of FIG. It is a partial sectional view in the axial direction of the output part of FIG. It is sectional drawing in the axial direction of the output part which concerns on another example. It is a perspective view and the side view of the output part of FIG. It is a schematic diagram of the magnetic circuit including an annular core and a magnetostrictive pattern, and is the sectional explanatory view which shows the dimensional relationship between members.

Hereinafter, an embodiment of the magnetostrictive torque detection sensor according to the present invention will be described with reference to the accompanying drawings. First, the schematic configuration of the magnetostrictive torque detection sensor will be described with reference to FIGS. 1 to 3. The motor with a speed reducer to which the magnetostrictive torque detection sensor shown in FIG. 1 is assembled is driven and transmitted from the motor 1 which is the drive source to the output unit 3 via the speed reducer 2. Hereinafter, a case where a torque change acting on the axial side surface of the detected body S assembled to the output unit 3 which is driven and transmitted from the motor 1 to the output unit 3 is detected by a magnetostrictive torque sensor in a non-contact manner will be described. The output shaft S1 and the disk portion S2 having a larger outer diameter than the output shaft S1 are integrally formed in the detected body S. The disk portion S2 is screwed and fixed to the speed reducer 2. The magnetostrictive torque detection sensor shall measure the torque change acting on the disk portion S2.

As an example of the object to be detected S, a material having a large magnetostrictive effect is preferable. For example, materials having a high magnetostrictive effect include permendur, Fe-Al (Alfer), Fe-Nix (Permalloy) and spheroidal graphite cast iron (JIS: FCD70). The inverse magnetostrictive effect is a phenomenon in which the magnetic characteristics change when stress is applied to the magnetic material from the outside. Further, if the object to be detected S is subjected to magnetic annealing in advance as necessary, the torque acting on the object to be detected S can be suitably detected, which will be described in detail later. Further, even if it is a non-magnetic material, torque can be detected by coating the metal magnetic material by thermal spraying or by press-fitting the magnetic cylinder into the shaft. The body S to be detected illustrated in FIG. 2 has a disk shape, but is not limited thereto. The detected body S may have a screw hole, a through hole, or the like as long as the outer shape is disk-shaped. In this embodiment, the disk portion S2 is screwed to the speed reducer 2 via the screw hole 3c. Further, the detected body S may be one that is scheduled to rotate, or may be a fixed one that is not scheduled to rotate.

As shown in FIG. 2, a magnetostrictive pattern 4 is formed around the axial side surface of the disk portion S2 of the detected body S. In the magnetostrictive pattern 4, the magnetostrictive coating layers made of the magnetostrictive material are formed in a chevron shape at equal intervals.
Specifically, as shown in FIG. 2, the first magnetostriction pattern 4a orbits from the inner diameter side of the disk portion S2 and is formed at equal intervals, and the second magnetostriction pattern 4b orbits close to the outside thereof. It is formed at equal intervals. A chevron-shaped magnetostrictive pattern 4 is formed by the first magnetostrictive pattern 4a and the second magnetostrictive pattern 4b adjacent to each other in the radial direction.
The magnetostrictive coating layers forming the first and second magnetostrictive patterns 4a and 4b are formed so as to have an inclination angle of ± 45 ° with respect to the axial center O of the object to be detected S. The magnetostrictive coating layer is formed by either metal plating, metal spraying, or adhesion of metal foil.

The magnetostrictive film layer is, for example, a soft high magnetostrictive material (for example, an amorphous alloy, a magnetostrictive film containing a ferromagnetic metal (Fe, Co, Ni, etc.), a magnetostrictive film containing metal glass (for example, Fe as a main component and an Fe content of 30%). Magnetostrictive film with a magnetostrictive film of ~ 80% atomic%, metal glass is Fe / Si / B / M, or Fe / Si / B / P / C / M (M = Cr, Nb, Ta, W, Ni, Co, Hf, The magnetostrictive film of Mo or M = none) and the metal glass may be a magnetostrictive film of Fe ₇₆ Si _5.7 B _9.5 P ₅ C _3.8 ).
These can be formed on the axial side surface of the object to be detected S (disk portion S2) by metal plating, metal spraying, or adhesion of metal foil. When spraying using metallic glass, the film of the metallic glass is formed by, for example, a high-speed frame spraying method or a plasma spraying method, and after the thermal spraying formation, heat treatment may be performed at a temperature lower than the glass transition temperature and higher than the Curie point temperature. Preferred (see WO2011 / 0163999).

In FIG. 3, the magnetic field generating unit M includes an annular core 5 arranged to face the magnetostrictive pattern 4. In the annular core 5, the end faces of the legs formed by bending a magnetic material formed in a U-shaped cross section on both sides in the radial direction via a crosslinked portion are arranged to face the magnetostrictive pattern 4.
Specifically, it is provided with a pair of first annular cores 5a and second annular cores 5b, and first detection coils 5d1 and second detection coils 5d2 provided around the recessed grooves 5c of each core. There is. The first annular core 5a and the second annular core 5b are assembled side by side from the inside to the outside in the radial direction so as to open the concave groove portion 5c outward in the axial direction to the core holding portion 5e formed in an annular shape. ing. The first annular core 5a and the second annular core 5b are formed by bending a magnetic plate material into a U-shaped cross section and forming them in an annular shape. As the magnetic plate material, a soft magnetic material is preferable, and a silicon steel plate or pure iron having a relatively high magnetic permeability is used. The first annular core 5a and the second annular core 5b may be magnetic nanowires. Further, for example, there are nanowires of amorphous alloy (metal glass), and fibers in which the wires are bundled can also be used. Further, the first annular core 5a and the second annular core 5b may be made of ferrite.

The first annular core 5a and the second annular core 5b have a U-shaped radial cross section, and have both side leg portions 5a1, 5b1 and bridge portions 5a2, 5b2 connecting them. The first annular core 5a and the second annular core 5b are assembled to the core holding portion 5e so that the first detection coil 5d1 and the second detection coil 5d2 circulate and pass through the concave groove portion 5c. When the core holding portion 5e is assembled into the central hole 3b of the case body 3a of the output portion 3, both side leg portions 5a1 of the first annular core 5a are arranged to face the first magnetostrictive pattern 4a, and both sides of the second annular core 5b. The legs 5a2 are arranged to face the second magnetostrictive pattern 4b (see FIG. 2).
When the first and second detection coils 5d1 and 5d2 are energized, a magnetic circuit is formed between the first annular core 5a and the first magnetostrictive pattern 4a, and between the second annular core 5b and the second magnetostrictive pattern 4b. A magnetic circuit is formed.

Further, as shown in FIG. 2, in the first magnetostriction pattern 4a and the second magnetostriction pattern 4b, the magnetic path formed in the detected body S (disk portion S2) is ± 45 with respect to the axial center O of the disk portion S2. It is formed so that it has an inclination angle of either °. As a result, when compressive stress acts in the direction of + 45 ° and tensile stress acts in the direction of -45 ° with respect to the axial center O of the disk portion S2, or tensile stress acts in the direction of + 45 ° and -45 °. When compressive stress acts in the direction of, the change in magnetic permeability that occurs in the object to be detected S due to the above-mentioned inverse magnetostrictive effect can be detected by converting it into torque from the amount of change in inductance of each detection coil 5c. The first magnetostriction pattern 4a and the second magnetostriction pattern 4b are preferably formed on the disk portion S2 as close as possible to the output shaft S1. In this embodiment, the first magnetostrictive pattern 4a and the second magnetostrictive pattern 4b are formed between the output shaft S1 and the screw hole 3c in the radial direction in the disk portion S2.

In the magnetic field generating portion M, the first annular core 5a and the second annular core 5b are held side by side from the inside to the outside in the radial direction, and the first annular core 5a and the first magnetostrictive pattern 4a are arranged so as to face each other. The bicyclic core 5b and the second magnetostrictive pattern 4b are arranged to face each other.
As a result, compressive stress acts on the side surface of the disk portion S2 in any of the circumferential directions in the + 45 ° direction, and tensile stress acts in the direction of −45 °, or tensile stress acts in the direction of + 45 ° and −45. In any case where compressive stress acts in the direction of °, it is possible to detect torque changes with high sensitivity.

Here, the detection principle of the torque acting on the detected body S will be described. When torque is generated in the detected object S, the magnetic permeability μ of the detected object S changes due to the inverse magnetostrictive effect, and as a result, it is measured as a change in the inductance of the detection coil 5d (first detection coil 5d1, second detection coil 5d2). can do. Specifically, the inductance of the detection coil 5d is proportional to the square of the number of turns N of the detection coil 5c, and the first and second annular cores 5a and 5b and the object to be detected are configured to sandwich the detection coil 5d. It is inversely proportional to the magnetic resistance Rm including the magnetic path of S. The reluctance Rm is inversely proportional to the cross-sectional area A of the magnetic path through which the magnetic flux flows and the relative permeability μr, and is proportional to the length of the magnetic path L through which the magnetic flux flows. Further, by increasing the amount of magnetic flux in a desired direction, it is possible to sensitively acquire a change in magnetic permeability μ. When a compressive force is applied in the same direction as the magnetic flux flowing from the first and second annular cores 5a and 5b that determine the inductance of the detection coil 5d into the detected body S, the value of the magnetic permeability μ of the detected body S decreases. As a result, the inductance of the detection coil 5d decreases. On the contrary, when a tensile force acts in the same direction as the flow of magnetic flux, the inductance of the detection coil 5d increases.

For example, in FIG. 2, when a tensile force acts on the disk portion S2 in the + 45 ° direction, the inductance of the detection coil 5d increases, and when a compressive force acts in the −45 ° direction, the inductance of the detection coil 5d decreases. This change in inductance is detected as a change in output voltage by a phase detection method using a lock-in amplifier, and the output voltage value when torque is acting on the object to be detected and the output voltage value when torque is not acting. The torque acting on the object to be detected S is detected based on the amount of change from the output voltage value.
The motor 1 is started, and the driving force is transmitted to the output unit 3 via the speed reducer 2. At this time, the torque change acting on the disk portion S2 integrated with the output shaft S1 is detected as an inductance change by the magnetic field generating portion M arranged to face the magnetostrictive pattern 4 formed on the axial side surface thereof. ing.

In this way, the magnetic field generating portion M is arranged close to the side surface of the detected body S (disk portion S2), and the first and second detection coils 5d1 and 5d2 are energized to energize the first and second annular cores 5a and 5b. The torque change can be detected from the magnetic flux change of the magnetic circuit formed between the first and second magnetostrictive patterns 4a and 4b facing the above. In particular, the first and second detection coils 5d1 and 5d2 are provided in the concave groove portions 5c of the first and second annular cores 5a and 5b formed in a U-shaped cross section, respectively, to form the first and second annular cores 5a and 5b. Since the magnetic flux can be concentrated on the magnetic circuits formed by the opposing first and second magnetostrictive patterns 4a and 4b, the detection sensitivity of the torque acting on the detected object S (disk portion S2) is improved. Therefore, the torque generated on the side surface of the detected body S over the entire circumference can be uniformly detected, and the sensor can be made thinner in the axial direction.

Next, another example of the magnetostrictive torque detection sensor will be described with reference to FIGS. 4 and 5.
The same members as those in the above-described embodiment shall be assigned the same number and the description shall be incorporated.
In the above embodiment, the object to be detected S is formed so as to overlap the axial side surface of the disk portion S2, but as shown in FIG. 4, the radial inside of the side surface of the disk portion S2 is the axial direction (plate thickness direction). A concave surface portion S3 having a thin wall is formed on the surface. A magnetostrictive coating layer is formed on the concave surface portion S3 by metal plating, metal spraying, or adhesion of a metal foil, and the magnetostrictive coating layer is polished flush with the concave surface portion S3 to form a chevron-shaped magnetostrictive pattern 4. Has been done. The magnetostrictive pattern 4 may be formed by engraving the concave surface portion S3 in advance in a chevron pattern shape, metal plating, metal spraying, or adhesion of metal foil. Alternatively, it may be formed by superimposing it on the concave surface portion S3 by metal plating, metal spraying, or adhesion of a metal foil.

Further, the magnetic flux generating portion 5 does not need to form the core holding portion 5e separately from the case body 3a. For example, as shown in FIG. 4, the first annular core 5a is arranged to face the first magnetostriction pattern 4a and the second annular core 5b is arranged to face the second magnetostriction pattern 4b in the case body 3a which is a non-magnetic material. They may be integrally assembled side by side in the radial direction. The first detection coil 5d1 and the second detection coil 5d2 are wound around the concave groove portions 5c of the first annular core 5a and the second annular core 5b.
In this case, the magnetic field generating portion M is arranged close to the thin-walled concave surface portion S3 of the disk portion S2 in the axial direction (plate thickness direction), and the magnetostrictive pattern 4 is flush with the concave surface portion S3 in a chevron pattern. Since the magnetic field generating portion 5 is formed so as to recede from it and can be arranged as close as possible to the magnetostrictive pattern 4, the leakage of magnetic flux is reduced and the miniaturization of the sensor in the axial direction can be promoted.

Further, in each of the above-described embodiments, the object to be detected S is screwed and fixed to the output unit 3 via the screw hole 3c, but the present invention is not limited to this. For example, as shown in FIGS. 5A and 5B, the detected body S may be a gear S4 having a tooth surface 6 formed on the outer peripheral surface of a disk portion integrally formed with the output shaft S1. The gear S4 may have a configuration in which the tooth surface 6 meshes with a planetary gear or another transmission gear provided in the speed reducer 2.

In this case, as in FIGS. 3 and 4, the magnetic flux generating portion M has a U-shaped radial cross-sectional shape in the first annular core 5a and the second annular core 5b, and both side legs 5a1, 5b1 and these. The core holding portion 5d (see FIG. 3) or the case body 3a so that the first and second detection coils 5d1 and 5d2 pass through the concave groove portion 5c surrounded by the crosslinked portions 5a2 and 5b2 connecting the two. It is assembled to (see Fig. 4).

FIG. 6A is a schematic view of a magnetic circuit from the second annular core 5b provided in the magnetic field generating portion M toward the second magnetostrictive pattern 4b, and FIG. 6B is a cross-sectional view showing a dimensional relationship between the members. Since the same applies to the magnetic circuit from the first annular core 5a to the first magnetostrictive pattern 4a, it is omitted. Turns N ₁ inside the first detection coil 5d1, the number of turns N ₂ of the outside of the second detection coil 5d2, the coil current I, the second annular core 5b (both side legs 5b1, bridge portions 5b2) and the second magnetostrictive pattern 4b The magnetic circuit formed between and is represented as shown in FIG. 6A. The total magnetic resistance is R, and the inductance L is as follows.

From the above, the inductance L is
The relative magnetic permeability μ _T changes when torque is applied to the disk portion S2 (disk). That is,
If all other arguments are constants

Annular yoke coils (first, second detection coil 5D1,5d2) when is in another set, the relative permeability mu _T1, mu _T2, when the inductance and L _1, L _2,
Finding the coil inductances L ₁ and L ₂ from Equation 5
A torque signal is obtained from the inductance changes of L ₁ and L _{2 in} the above equation 6.

As a result, the changes in the inductances L ₁ and L ₂ in Equation 2 are converted into voltage signals, signal processed by the circuit, and converted into torque signals. In this case, although the signal strengths of the internal and external sensors are different, it is necessary to perform amplification processing after detecting the signal (increasing the external signal sensitivity in terms of circuit and software). Thus, as the inductance L _1, L ₂ that it is detected by the magnetic circuit of the inner and outer are equal to each other, in advance first, second annular core 5a, 5b structure or the material of the first, second magnetostrictive pattern 4a, Area or material of 4b, distance of first and second magnetostrictive patterns 4a and 4b from the torque generation source on the detected object S, number of turns N ₁ , N ₂ or material of the first detection coil 5d1 and the second detection coil 5d2. By adjusting at least one of the above, the signal strength can be made the same by canceling the amount of the detected output offset.

Alternatively, the dimensions of the first annular core 5a and the second annular core 5b are designed under the following conditions, and the inductances L ₁ and L ₂ are made equal.
In Equation 7, if N ₁ = N 2, A ₁ = A ₂ , and B ₁ = B ₂ , the two coils are bridge-connected to obtain positive and negative symmetric torque outputs. In this case, the offset is 0. Furthermore, if the differential values by μ _T are equalized, the positive and negative sensitivities to torque will also be equal.
The signal strength detected by the internal and external sensors may be the same by physically changing μ _T (area of chevron pattern, distance from the center, material, etc.), N (number of turns), etc. so as to satisfy Equation 3. ..
As a result, in the magnetic circuit including the first magnetostriction pattern 4a and the second magnetostriction pattern 4b forming the chevron pattern on the disk-shaped object to be detected S2, the positive and negative symmetric torque output is output with the offset component as zero. Therefore, a stable output can be obtained that is not easily affected by electromagnetic noise and temperature changes between the coils.

As described above, according to the above configuration, a magnetostrictive torque detection sensor capable of uniformly detecting the torque generated over the entire side surface of the object S to be detected and thinning the sensor in the axial direction. Can be provided.

In each of the above-described embodiments, a pair of magnetostrictive patterns 4a and 4b are formed in the object S to be detected, in which the magnetic flux chain intersection surfaces of the annular cores 5a and 5b intersect at inclination angles of + 45 ° and −45 °, but only one of them. May be provided, or 3 or more magnetostrictive patterns may be provided.
Further, a search coil for detecting a change in the magnetic flux density passing through each core may be wound around the crosslinked portions 5a2 and 5b2 of the first and second annular cores 5a and 5b.
Further, the first and second annular cores 5 were integrally formed of a magnetic material in a U shape having both side leg portions 5a1, 5b1 and cross-linking portions 5a2, 5b2 connecting them, but both side leg portions 5a1,5b1. Is also formed of a magnetic plate material, and the crosslinked portions 5a2 and 5b2 may be formed of an annular magnetic plate provided on the case body 3a.
Further, the case 3a, the first annular core 5a, and the second annular core 5b may be integrally assembled by insert molding.

1 Motor 2 Reducer 3 Output part 3a Case body 3b Center hole 3c Thread hole S Detected body S1 Output shaft S2 Disc part S3 Concave part S4 Gear 4 Magnetostriction pattern 4a 1st magnetostriction pattern 4b 2nd magnetostriction pattern 5a Single annular core 5a1,5b1 Leg 5a2, 5b2 Bridge 5b Second annular core 5c Recessed groove 5d Detection coil 5d1 First detection coil 5d2 Second detection coil 5e Core holder 6 Tooth surface M Magnetostrictor

Claims (7)

A magnetostrictive torque sensor that non-contactly detects changes in torque acting on the axial side surface of the object to be detected provided in the output unit that is driven and transmitted from the drive source.
A magnetostrictive pattern formed around the side surface of the object to be detected and having magnetostrictive coating layers made of a magnetostrictive material formed in a chevron shape at equal intervals.
An annular core in which a magnetic material formed in a U-shape in cross section is arranged on both side legs along a radial direction of the object to be detected via a crosslinked portion, and the end faces of the legs are arranged to face the magnetostrictive pattern, and the above. It is provided with a magnetic field generating portion having a detection coil provided around the concave groove portion of the annular core.
The magnetic field generating portion is detected so that a magnetic circuit is formed between the inner diameter side leg end surface and the outer diameter side leg end surface of the annular core and the magnetostrictive pattern facing the detection coil. A magnetostrictive torque detection sensor characterized by being assembled close to the body. The first magnetostrictive pattern and the second magnetostrictive pattern formed concentrically around the side surface of the object to be detected are arranged in close proximity to form the chevron-shaped magnetostrictive pattern, and each magnetostrictive coating layer forming the magnetostrictive pattern. Is the magnetostrictive torque detection sensor according to claim 1, which is formed so as to have an inclination angle of any of ± 45 ° with respect to the axis of the object to be detected. In the magnetic field generating portion, the first annular core and the second annular core are held side by side from the inside to the outside in the radial direction of the detected body, and the first annular core and the first magnetostrictive pattern are arranged to face each other. The magnetostrictive torque detection sensor according to claim 2, wherein the second annular core and the second magnetostrictive pattern are arranged to face each other. The magnetostrictive torque detection sensor according to any one of claims 1 to 3, wherein the magnetostrictive coating layer is formed by metal plating, metal spraying, or adhesion of a metal foil. The magnetostrictive torque detection sensor according to any one of claims 1 to 4, wherein the magnetostrictive coating layer is formed so as to overlap the side surface of the object to be detected. The magnetostrictive torque detection sensor according to any one of claims 1 to 4, wherein the magnetostrictive coating layer is formed on a side surface of the object to be detected so as to be overlapped with a concave surface formed in a thin shape in the axial direction. In each of the magnetic circuits in the radial direction of the body to be detected first annular core and a first magnetostrictive pattern, the second annular core and a second magnetostrictive pattern is formed to face inside and outside, the inductance L ₁ of the magnetic circuit of one _another, At least one of the structure or material of each annular core, the area or material of the magnetostrictive pattern, the distance of the magnetostrictive pattern from the torque source on the detected object, the number of coil turns or the material is adjusted so that L ₂ is equal to each other. The magnetostrictive torque according to any one of claims 1 to 6, wherein the first detection coil wound around the first annular core and the second detection coil wound around the second annular core are bridge-connected. Detection sensor.