JPH0678956B2 - Torque sensor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque sensor, and more particularly to a torque sensor that measures rotational torque accurately without contact.

(Prior Art) In general, the number of devices driven by rotational driving force is very large, and its application fields are diverse. Torque control often occupies an important position in controlling such devices. That is, the torque is one of the most basic and important parameters when controlling the rotary drive system,
When the information on the torque and the number of revolutions is obtained, the product of them is proportional to the horsepower, so that it becomes possible to grasp the generation state and transmission state of power.

As a conventional torque sensor, for example, there is a torque sensor described in Japanese Patent Application Laid-Open No. 54-17228, which is applied to a steering force detecting device for detecting a steering force applied to a steering wheel of a vehicle. In this device, a steering wheel and a steering shaft are connected via an elastic body, and a relative torsional displacement generated between the steering wheel and the steering shaft due to a torsional action generated in the elastic body according to the magnitude of the steering torque during steering. It is detected by turning on and off the contacts that are interposed between the steering wheel and the steering shaft. However, in such a device, contacts and microswitches that are turned on and off by twisting displacement are provided, so high work accuracy is required for the placement of these contacts, and the amount of relative twisting displacement that turns on is large. There is a problem that it is difficult to individually set the relative torsional displacement amount that turns OFF or OFF. Further, the device described in Japanese Patent Laid-Open No. 55-44013 is provided with an electric displacement detection unit such as a strain gauge on an input shaft to which steering torque is transmitted from the steering wheel, and the steering torque and steering resistance input from the steering wheel. It detects the relative torsional displacement of the input shaft that occurs depending on the difference between the temperature and the temperature.Because an electrical displacement detector such as a strain gauge was fixed to the input shaft to detect the torsional displacement of the input shaft, There is a problem that it is susceptible to changes, its operation is unstable, and its reliability is poor.

Therefore, as a solution to such a problem,
JP-A-58-194664, JP-A-58-218627, JP-A-58-
No. 105877, No. 57-192872, No. 58-101153,
The ones disclosed in JP-A-58-5626 and JP-A-61-21861 are known.

For example, in the device described in JP-A-58-194664, a column shaft having one end connected to a steering wheel and the other end connected to a steering gear is divided, and the two divided shafts are connected via an elastic body. It is provided in a steering position connected so as to enable relative rotational displacement, and the relative rotational displacement of these two shafts is converted into an axial displacement, which is added to the steering wheel according to the magnitude of the axial displacement. The steering force applied is detected. Further, there is the one described in the above-mentioned JP-A-61-21861 as one in which the twist of the torsion bar mechanism is converted into a change in electrostatic capacity.

(Problems to be Solved by the Invention) However, in such a conventional device, the torsional displacement of the torsion bar mechanism is detected by using a member such as a switch, or the relative rotational displacement is determined as the axial displacement. In the case of so-called contact type torque sensors such as those that convert, the structure is complicated, the number of mechanical and electrical parts of the detector is large, and considerable accuracy is required for mounting, which not only increases the manufacturing cost. Detection accuracy may deteriorate due to environmental changes such as temperature and humidity. That is, when the torque is detected as the sensor, the non-contact type torque sensor is desirable from the viewpoint of reliability such as wear resistance and safety because the rotational axis is the target. On the other hand, even a non-contact type torque sensor, for example, one that photoelectrically detects the amount of torsional displacement (see Japanese Patent Laid-Open No. 58-5626) cannot be used particularly in a heavily soiled place. Sometimes. In addition to the above-mentioned problems, in the conventional device, whether the torque sensor is a contact type or a non-contact type, the conventional device detects the rotational displacement direction (that is, the direction in which the torque acts) and the stationary torque. Is quite difficult, and a torque sensor that solves these problems has not been realized yet.

As described above, there is a demand for the appearance of a torque sensor that can accurately detect rotation and static torque, which are extremely important parameters when controlling a rotation drive unit such as an engine or an electric motor, in a non-contact manner at low cost. Further, in order to apply such a torque sensor to a recent precise control device,
Extremely high precision tends to be required regardless of usage conditions.

(Object of the invention) Therefore, the present invention focuses on a physical quantity called a magnetic field that is not affected by environmental changes such as temperature and humidity and dirt, and converts a torsional displacement into a change in the magnetic flux by a predetermined structure. A plurality of magnetic detection elements are provided to detect the change in a non-contact manner, and at least two or more of the magnetic detection elements are detected at predetermined angles about the axis of the first shaft in the first and second pickup paths. By installing in the, the torsional displacement can be appropriately measured as a change in torque amount,
It is an object of the present invention to provide a highly accurate non-contact type torque sensor that has a simple structure, has good responsiveness, and can detect torque at low cost regardless of whether it is stationary or rotating.

(Means for Solving Problems) The torque sensor according to the present invention has the first object to achieve the above object.
The tip portion of the shaft is connected to the second shaft as a structure capable of generating torsional displacement, and a predetermined number of N poles and S poles are alternately arranged as fixed magnetic poles so as to surround the periphery of the connection portion. The first pickup path and the second pickup path, which are fixed to the shaft and have the same number of N poles and S poles, are arranged so as to face the intermediate positions of the respective magnetic poles, and flow through the first and second pickup paths. A plurality of magnetic detection elements for detecting a change in magnetic flux are arranged so as not to contact the first shaft, and at least two or more of the magnetic detection elements are arranged in the first and second pickup paths. One shaft is provided at every predetermined angle so as to correct mechanical eccentricity from the axis, and the second axis is provided.
When the first shaft is torsionally displaced with respect to the shaft, the amount of magnetic flux flowing through the first and second pickup paths is changed depending on which side of the first pickup path or the second pickup path the N pole approaches. The torsional displacement of the first shaft with respect to the second shaft is detected from the change in the magnetic flux.

(Operation) In the present invention, the tip portion of the first shaft is connected to the second shaft as a structure capable of generating torsional displacement, and a predetermined number of N poles and S poles are fixed magnetic poles so as to surround the periphery of the connection portion. Are alternately arranged and fixed to the second shaft, and the same number of first pickup paths and second pickup paths as the N poles and the S poles are arranged so as to face the intermediate positions of the respective magnetic poles. It Further, a plurality of magnetic detection elements that detect changes in the magnetic flux flowing through the first and second pickup paths are provided so as not to contact the first shaft, and at least two or more of the magnetic detection elements are provided. Objects are provided at predetermined angles about the axis of the first shaft in the first and second pickup paths, and when the first shaft is twisted and displaced with respect to the second shaft, the N pole becomes the first pickup path or the second pickup path. The amount of magnetic flux flowing through the first and second pickup paths is changed depending on which side of the pickup path is approached, and the twist displacement of the first shaft with respect to the second shaft is detected in a non-contact manner from the change in the magnetic flux. Therefore, the structure is simple, the response is good, and
Torque can be accurately measured at low cost regardless of rotation.

(Example) Hereinafter, the present invention will be described with reference to the drawings.

1 to 12 are views showing a first embodiment of the present invention.
The drawing is an exploded perspective view of this embodiment, FIG. 2 is a vertical side view, and FIG. 3 is a front view. This embodiment is an example using two magnetic detection elements.

First, the configuration will be described. In FIG. 1, reference numeral 1 is a first shaft, and the first shaft 1 is connected to a second shaft 3 via a small diameter portion 2 for slightly lowering torsional rigidity, as shown by A and B in the figure. The rotational force of the first shaft in the circumferential direction is transmitted to the second shaft 3 via the small diameter portion 2. Further, as shown in the vertical side view of FIG. 2, the outer peripheral surface 3a of the second shaft 3 has a projecting end portion 4a of a cylindrical mold member (nonmagnetic material) 4 formed so as to enclose the small diameter portion 2. The mold member 4 is fitted and fixed, and forms a torque detection mechanism 21 in combination with a pickup member 7 and Hall elements 13 and 14 described later. On the other hand, a donut-shaped magnetic material embedded portion 4b is formed on the other end of the mold member 4, and the magnetic material embedded portion 4b has a cut surface (end surface) 4c perpendicular to the axial direction. In the body-embedded portion 4b, the magnetic body 5a arranged so that the end face 4c faces the N pole, and the end face 4c.
And eight magnetic bodies 5b arranged so as to face the S pole are alternately arranged concentrically and at equal intervals. Further, the other end of each magnetic body 5a, 5b is connected to an annular common ring 6, and the common ring 6 forms a part of a closed loop magnetic path for the magnetic field emitted from each magnetic body 5a, 5b. . Common ring 6 and each magnetic body 5
The a and 5b are embedded in the magnetic material embedded portion 4b, and are integrally formed with the magnetic material embedded portion 4b made of a non-contact body. In the present embodiment, the number of the magnetic bodies 5a and 5b is eight, respectively, but of course the number is not limited to this, and another number may be used as long as the north pole and the south pole alternately face the end surface 4c at equal intervals. It may be one of the embodiments.

On the other hand, the outer peripheral surface 1a on the small diameter portion 2 side of the first shaft has an end surface 4c.
A disk-shaped pick-up member 7 facing the end face 4c and having a minute gap is fitted and fixed, and the input-side end face 7a of the pick-up member 7 is circumscribed with the end face 7a and the outer ring 8 and its outer surface. An inner ring 9 is provided inside. Also, the end surface 7b of the pickup member 7 facing the end surface 4c
The magnetic path piece 10a and the magnetic path piece 10b, which become magnetic paths by receiving the magnetic force from the magnetic material 5a or 5b, are alternately concentric with eight magnetic material pieces 5a and 5b so as to respond one-to-one. The magnetic path pieces 10a are connected to the outer ring 8 and the magnetic path pieces 10b are connected to the inner ring 9. The magnetic path piece 10a and the outer ring 8 form a first pickup path 11, and the magnetic path piece 10b and the inner ring 9 form a second pickup path 12. Here, the common ring 6, the magnetic path pieces 10a and 10b, the outer ring 8 and the inner ring 9 are preferably made of a material through which magnetic lines of force can easily pass, and are made of, for example, permalloy or ferrite. The generated magnetic force is guided to the outer ring 8 and the inner ring 9 via the magnetic path pieces 10a and 10b.
By the way, the magnetic path pieces 10a and 10b are integrally formed in the pickup member 7 made of a non-magnetic material like the magnetic materials 5a and 5b, and in the steady state (that is, when the torque is 0), the magnetic path pieces of FIG. As shown in the front view, the magnetic material 5a or 5b is the magnetic path piece.
It is configured to be located exactly in the middle of 10a and 10b. Therefore, the gap space l _A from the magnetic body 5a to the magnetic path piece 10a and the gap space l _B from the magnetic body 5a to the magnetic path piece 10b are equal to each other, and similarly, the magnetic body 5b to the magnetic path piece 10b. The gap space l _A up to and the gap space l _B from 5b to the magnetic path piece 10a are equal. Therefore, as shown in FIG. 1, the first shaft 1 has a circumferential direction A (or B).
When the rotational force is applied, the gap spaces l _A and l _B change by a predetermined amount according to the rotational force. Further, between the outer ring 8 and the inner ring 9 described above, there is no contact with these rings or the pick-up member 7 and a right angle to the magnetic field applied from the outer ring 8 to the inner ring 9 (or to the inner ring 9 or the outer ring 8). The Hall element (first magnetic detection element) 13 is arranged in such a position as to be 180 degrees with respect to the Hall element 13 and the first shaft 1.
A Hall element (second magnetic detection element) 14 is arranged at a position facing the angle of °. The Hall element 13 and the Hall element 14 are fixed to the printed circuit board 15 with an adhesive material or the like. A member (not shown) for detecting and processing the signals from the Hall elements 13 and 14 is arranged on the printed circuit board 15, and the printed circuit board 15 is provided with a support member 15a that is fixed to the printed circuit board. It is fitted on one shaft 1 so as to be rotatable and displaceable. The Hall elements 13 and 14 are sensors that utilize the solid Hall effect, and are elements that generate an output voltage proportional to the strength of the magnetic field. The description is omitted.

FIG. 4 is a diagram showing an arithmetic circuit for detecting the output from the Hall elements 13 and 14 as a torque amount. In the figure, OP1～OP4 the operational amplifier 1, R ₁ to R ₁₈ is a resistor, a Hall element 13 the positive output voltage Q _1a to the magnetic field directed from the outer ring 8 to the inner ring 9, and vice It is assumed that the negative output voltage Q _1b is output with respect to the magnetic field in the opposite direction, and the Hall element 14 similarly outputs the positive output voltage Q _2a with respect to the magnetic field directed from the outer ring 8 to the inner ring 9 and the opposite magnetic field. On the other hand, the negative output voltage Q _2b is output (see FIG. 5). The non-inverting amplifiers OP1 and OP2 are
For example, a constant voltage circuit as shown in FIG.
The power supply voltage [v] is supplied and the differential amplifier OP
3, OP4 by a constant voltage circuit as shown in Figure 6 (b)
A power supply voltage of 10 [V] is supplied. OP1, OP2 is configured as non-inverting amplifier, to the non-inverting input terminal of the OP1 and Q _2a through resistor R ₂ and Q _1a via a resistor R ₁ is connected in parallel, the non-inverting input of OP2 Q is connected to the terminal side via resistor R _5.
1b and Q _2b are connected in parallel via R ₆ . Therefore, OP1 is the positive output voltage Q _1a, to form the adder circuit Q _2a, OP2 negative output voltage Q _1b, to form an adder circuit of Q _2b. The output terminal of the OP1 is is connected to the inverting input terminal side of the resistor through R ₉ OP3, it is connected via a resistor R ₁₇ to the non-inverting input terminal side of OP4. Similarly, O
The output terminal of P2 is connected to the non-inverting input terminal side of the OP3 via the resistor R _12, is connected to the inverting input of OP4 via a resistor R _14. Here, the resistors _{R 3, R 4, R 7} , R 8,
R ₉ , R ₁₀ , R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₁₅ , R ₁₆ , R ₁₇ , and
The value of R ₁₈ determines the operating state of OP1 to OP4, and
The above resistance values are determined so that the operating characteristics of P1 and OP2 or OP3 and OP4 are equal.

The differential amplifiers OP3 and OP4 receive the outputs from OP1 and OP2, and when the difference is positive, for example, when the torque is applied in the right-hand screw direction, the output voltage E _TR is output from the output terminal of OP3, and when the difference is negative. Outputs the output voltage E _TL from the OP4 output terminal, assuming that torque is applied in the left-hand screw direction.

Next, the operation will be described.

The torque sensor according to the present invention has a mechanical torsional displacement generated between the first shaft 1 and the second shaft 3 when the Hall elements 13 and 14 detect the magnetic force generated from the magnetic bodies 5a and 5b. Is the gap space between the magnetic bodies 5a and 5b and the magnetic path pieces 10a and 10b.
The changes in l _A and l _B (in other words, changes in the spatial magnetic path length) are recognized as changes in the gap spaces l _A and l _B , and the Hall element 1
The torque is detected in a non-contact manner by detecting the change in the strength of the magnetic field applied to 3 and 14. Next, the basic idea of the present invention will be described with reference to FIGS. 7 and 8 by taking the case of one magnetic detection element (Hall element 13) as an example. FIG. 7 (a) is a diagram schematically showing a part of the torque detection mechanism 21 in a stationary state, and FIG. 7 (b) is a diagram showing the rotational force in the circumferential direction A as shown in FIG. A case where the rotational force is applied in the circumferential direction B is schematically shown in FIG. Further, FIG. 8 is a perspective view schematically showing a part of the torque detection mechanism 21 in the steady state.

Since torque is not constantly applied, the gap space l _A from the magnetic body 5a to the magnetic path piece 10a and the magnetic body 5 are
The gap space l _B from a to the magnetic path piece 10b is equal, and the positional relationship between each magnetic body and the magnetic path piece is uniform at any place. Therefore, as shown in FIG.
The pair of magnetic bodies 5a and 5b and the magnetic path pieces 10a and 10b can be described as representative examples. Now, the magnetic force generated from the N pole of the magnetic body 5a is the gap space as shown by the solid arrow.
l _A , magnetic path piece 10a, outer ring 8 and Hall element 13
To the S element of the magnetic body 5b through the inner ring 9, the magnetic path piece 10b, and the gap space l _A orthogonally to the Hall element 13.
It reaches the pole (the strength of the magnetic field acting on the Hall element 13 in the direction of the arrow of this solid line is called the magnetic field H _A ). The magnetic force generated from the N pole of the magnetic body 5b reaches the S pole of the magnetic body 5a through the common ring 6. In this way, the magnetic bodies 5a and 5b and the magnetic path piece 10
The a, 10b, the outer ring 8, the inner ring 9 and the common ring 6 form a closed loop magnetic path across the gap space l _A (see solid line arrow in the figure). However, the magnetic force generated at the N pole of the magnetic body 5a is equally applied to the magnetic path piece 10b side on the other hand, and as shown by the broken line arrow in FIG. (The strength of the magnetic field acting on the Hall element 13 in the direction of the broken line arrow is referred to as the magnetic field H _B ). In this case, the Hall element
The strength of the magnetic field applied to 13 is actually determined by the difference in the size of the gap space l _A or l _B whose permeability is extremely smaller than that of the magnetic path piece with high permeability and the inner and outer rings. . In addition, since each member of the magnetic path pieces 10a, 10b, the outer ring 8, the inner ring 9 and the common ring 6 forms a common magnetic path during steady state and non-steady state, secular change in each of these members. Even if there is deterioration due to, the accuracy of torque detection does not decrease.

As described above, in a steady state where no torque is applied, the gap spaces l _A and l _B described above are equal to each other, so that the magnetic fields H _A and H _B applied to the Hall element 13 have equal strengths and cancel each other out. Is not detected.

At unsteady state (when torque is applied) As shown in FIG. 7 (b), when the rotational force is applied in the circumferential direction A, the gap space l _A from the magnetic body 5a to the magnetic path piece 10a and the magnetic field Gap space l _A from body 5b to magnetic path piece 10b
Are all increased, both smaller than the gap space l _B from the gap space l _B and the magnetic body 5b of the opposite magnetic bodies 5a to magnetic path piece 10b to the magnetic path piece 10a. Therefore, along with this, the magnetic field H _B becomes larger than the magnetic field H _A , and the degree thereof is proportional to the magnitude of the twist angle applied in the A direction (see FIG. 9). For example, if the direction of the magnetic field applied to the Hall element 13 by the rotational force in the A direction is positive and the output of the Hall element 13 is set so that its output voltage has a positive value,
As shown in FIG. 9, the magnitude and direction of the generated torque and the static torque can be detected appropriately. Further, as shown in FIG. 7 (c), when the rotational force is applied in the direction of the circumferential direction B, the magnetic field H _A becomes larger than the magnetic field H _B, and the torque in the opposite direction to the above case is detected. be able to.

As described above, in the present embodiment, when the magnetic force generated from the magnetic bodies 5a and 5b is detected by the hall element 13, the torsional displacement generated between the first shaft 1 and the second shaft 3 causes the magnetic body 5a, It is perceived as a change in the gap space l _A , l _B between the 5b and the magnetic path piece 10a, 10b, and this change in the gap space l _A , l _{B is} a change in the magnetic field strength without contact with the pickup member 7. It is accurately detected by the Hall element 13 provided.

By the way, until now one magnetic detection element (Hall element)
Although the operation of the present invention has been described focusing only on 13), the same operation actually works in other magnetic detection elements (Hall element 14) (however, the output of the Hall element 14 is 180 ° out of phase with the output of the Hall element 13).

As described above, in the present embodiment, as described in the conventional problems, there is no rotating portion and the structure is extremely simple as compared with a conventional device such as a device that converts relative rotational displacement into axial displacement. Therefore, it is possible to realize a torque sensor that is excellent in responsiveness and reliability and has high measurement accuracy at low cost. Further, in addition to having a simple structure, since the Hall elements 13, 14 and the like can be adjusted after the mold member 4 and the pickup member 7 are attached, it is difficult to perform a difficult work requiring high precision in the attachment of these members. Does not need
Moreover, since the information of the rotating torque is detected in a non-contact manner in the present invention, not only the improvement of the measurement accuracy, but also the abrasion resistance, the reliability such as the safety can be dramatically improved, It is possible to accurately detect the static torque, which was difficult to measure with the conventional device.

In addition to the effects as described above, in this embodiment, the first shaft 1 is placed at a position opposite to the angle of 180 ° about the axis of the first shaft 1.
Since the individual magnetic detection elements are provided, if the air gap A and the air gap B are different due to machining or assembling errors as shown in FIG. Even if a trill ripple is generated for each rotation (see FIG. 11), this ripple is canceled by the two magnetic detection elements having 180 ° different phases, and only the required rotation torque can be detected. Therefore, not only the detection accuracy is remarkably improved, but also in the unlikely event that the shaft is eccentric or the magnetic detection element is damaged due to an accident or the like, the rotational torque can be appropriately detected. FIG. 12 is a characteristic diagram in which the relationship between the rotation angle and the output voltage of the Hall elements 13 and 14 when the eccentricity is present between the inner ring 9 and the outer ring 8 is measured. An arithmetic circuit as shown in the figure properly erases the ripple component related to the eccentricity.

If the present invention having the above features is applied to a steering device for detecting a steering force of an automobile, for example, it is extremely suitable for controlling the steering force.

In this embodiment, as an example of the detection of the rotation torque, FIG. 9 shows a mode in which the rotation angle is only ± 6 °, but the invention is not limited to this. For example, the torsional rigidity of the magnetic body, the magnetic path piece, and the shaft is adjusted. By doing so, it is of course possible to detect a wide range of static and dynamic torques.

Further, in the present invention, although the tip end portion of the first shaft is connected to the second shaft as a structure capable of generating a torsional displacement, the first shaft and the second shaft may be separate members, Alternatively, as in this embodiment, the first and second
It goes without saying that both the shaft and the shaft may be formed of a single member.

Further, in the present embodiment, a fourth embodiment is provided as a rotation torque detection circuit.
Although the arithmetic circuit as shown is shown, the present invention is not limited to this, and another circuit may be used as long as it is a circuit that cancels the torque ripple.

The above-described first embodiment is an example in which two magnetic detection elements that perform so-called eccentricity correction are used and are opposed to each other at every 180 °, but the number is not limited to two to perform eccentricity correction. For example, if the element is 120 °
Three may be provided for each, or further four or more may be provided for more accurate eccentricity correction.

Further, one of the points of the present invention is that a plurality of magnetic detection elements are provided. In the first embodiment, all of the elements are used for eccentricity correction. The present invention is not limited to the above-mentioned use, but may be used as a device for correcting non-uniformity of magnetic flux density in addition to mechanical factors. This aspect will be shown in the second embodiment below.

13 to 15 are views showing a second embodiment of the present invention, and this embodiment is the same as the first embodiment except that two more magnetic detecting elements are added. Therefore, the same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 13, except for the positions of the Hall elements 13 and 14, the Hall element (third magnetic detection element) 16 and the Hall element 16 are relative to each other at an angle of 180 ° in the same state as the case of the Hall elements 13 and 14. A Hall element (fourth magnetic detection element) 17 is arranged at the position where the Hall elements are connected, and the Hall elements 13, 14, 16 and 17 are connected as shown in the block diagram of FIG.

Therefore, in this embodiment, when the magnetic flux flows into the magnetic path pieces 10a, 10b from the tips of the magnetic bodies 5a, 5b, the air gap junction point between the magnetic bodies 5a, 5b and the magnetic path pieces 10a, 10b (thirteenth C, D in the figure
Even if the magnetic flux density becomes uneven in (see section), it can be canceled out by averaging it by the third Hall element 16 as shown in FIG. Therefore, in the present embodiment, in addition to the effect of the first embodiment, it is possible to correct the nonuniformity of the magnetic flux density due to the difference in the positional relationship of the members, and it is possible to further improve the accuracy. The hall element 17 corresponds to the hall element 14 of the first embodiment and has the same purpose.

(Effects) According to the present invention, the torsional displacement is converted into a change in the amount of magnetic flux by a predetermined structure, and the change in the amount of magnetic flux is detected by a plurality of magnetic detection elements arranged in a non-contact manner. Since at least two or more of them are provided at predetermined angles around the axis of the first shaft in the first and second pickup paths, the torsional displacement is appropriately measured as a change in torque amount. However, the torque can be accurately detected in a non-contact manner at low cost regardless of whether it is stationary or rotating, because it is simple and responsive.

[Brief description of drawings]

1 to 12 are views showing a first embodiment of a torque sensor according to the present invention. FIG. 1 is an exploded perspective view thereof, FIG. 2 is a longitudinal side view thereof, and FIG. 3 is a front view thereof. FIG. 4 is a circuit diagram showing the arithmetic circuit, FIG. 5 is a characteristic diagram of the Hall element, FIG.
FIG. 6A is one circuit diagram showing the constant voltage circuit, and FIG. 6B is another circuit diagram showing the constant voltage circuit.
Figure (a) is a schematic diagram for explaining the operation in the steady state,
FIG. 7 (b) is a schematic view for explaining the action when torque is applied in one direction, and FIG. 7 (c) is for explaining the action when torque is applied in the other direction. FIG. 8, FIG. 8 is a schematic perspective view for explaining the action, FIG. 9 is a characteristic diagram of rotational torque for explaining the effect, and FIG. 10 is for explaining the action. Is a front view, FIG. 11 is a rotation torque characteristic diagram for explaining the action, FIG. 12 is a rotation torque characteristic diagram for explaining the effect, and FIGS. 13 to 15 are second embodiments of the present invention. FIG. 13 is a diagram showing an example, FIG. 13 is a front view thereof, FIG. 14 is a block diagram thereof, and FIG. 15 is a rotational torque characteristic diagram for explaining the effect. 1 ...... First shaft, 2 ... Small diameter part, 3 ... Second shaft, 5a, 5b ... Magnetic material, 10a, 10b ... Magnetic path piece, 11 ... First pickup path, 12 ... Second Pickup path, 13, 14 ... Hall element (magnetic detection element), 16, 17 ... Hall element (third magnetic detection element).

Claims (3)

[Claims] 1. A tip portion of a first shaft is connected to a second shaft as a structure capable of generating a torsional displacement, and a predetermined number of N poles and S poles are alternately arranged as fixed magnetic poles so as to surround the periphery of the connection portion. The first pickup path and the second pickup path as many as the N poles and the S poles are arranged so as to face the intermediate positions of the respective magnetic poles. , A plurality of magnetic detection elements for detecting a change in magnetic flux flowing through the second pickup path are arranged so as not to contact the first shaft, and at least two of the magnetic detection elements are first , Second
The pickup shaft is provided at predetermined angles about the axis of the first shaft so as to correct mechanical eccentricity from the axis of the first shaft, and when the first shaft is twisted and displaced with respect to the second shaft, the N pole is the first The amount of magnetic flux flowing through the first and second pickup paths is changed by approaching either the pickup path or the second pickup path, and the torsional displacement of the first shaft with respect to the second shaft is detected from the change in the magnetic flux. A torque sensor characterized in that 2. The magnetic detection element is composed of two elements, which are arranged to face each other at an angle of 180 ° about the axis of the first shaft, as elements for correcting eccentricity. The torque sensor according to the first section. 3. The magnetic detection element is provided with two elements arranged at positions opposite to each other at an angle of 180 ° about the axis of the first shaft, and is arranged at a position other than these positions to perform eccentricity correction. The torque sensor according to claim 1, further comprising a third element that corrects the non-uniformity of the magnetic flux density between the first and second pickup paths.