JP2008216019A - Torque sensor and electric power steering device - Google Patents

Abstract

Magnetization is easy and the number of man-hours can be reduced, and variations in magnetization intensity can be reduced to prevent damage to the magnet surface.
An elastic member connected coaxially between a first shaft and a second shaft and a first shaft or one end of the elastic member are fixed to a torque sensor and magnetized in two poles in the axial direction. A plurality of claw portions are provided so as to face the magnet side surfaces and parallel to the magnet axial direction, and are fixed to both ends of the magnet axial direction so that the claw portions are alternately positioned. The pair of magnet side magnetic bodies and the second shaft or the other end side of the elastic member are connected to form a magnetic circuit together with the magnet and the pair of magnet side magnetic bodies, and the relative relationship between the pair of magnet side magnetic bodies A magnetic body having a structure in which the magnetic flux density generated in the magnetic circuit changes when the position changes, and a magnetic detection element for detecting the magnetic flux density generated in the magnetic circuit are provided.
[Selection] Figure 1

Description

  The present invention relates to a torque sensor that measures the state of torsion torque in a mechanism that transmits rotational power, such as an electric power steering device (EPS) of an automobile, and an improvement of an electric power steering device including the torque sensor.

  As torque sensors for measuring the state of torsional torque in a mechanism for transmitting rotational power, those disclosed in Patent Document 1 and Patent Document 2 below are known.

These torque sensors use, for example, two magnetic sensors, measure the angle with a screw as a voltage change from the output results obtained by operating and amplifying output signals of different polarities, and detect these two abnormalities by detecting an abnormality of the voltage change. This makes it possible to detect an abnormal state of two magnetic sensors.
Japanese Patent No. 2741388 JP 2003-149062 A

  However, in the torque sensors disclosed in Patent Document 1 and Patent Document 2, it is necessary to magnetize the magnet in multiple poles, and there is a problem that the number of magnetizing steps is large and the manufacturing is complicated. In addition, since these torque sensors need to be magnetized in multiple poles, there is a problem that the magnetization intensity varies, and the measurement accuracy as a torque sensor deteriorates.

  Furthermore, in the torque sensors disclosed in Patent Document 1 and Patent Document 2, since it is necessary to narrow a gap between the magnet surface and the opposing magnetic body, a protective layer cannot be provided on the magnet surface, and assembly is performed. There is a problem that the surface of the magnet is easily damaged due to contact due to a defect, and improvement has been desired.

  The present invention has been made in consideration of the above points, and intends to propose a torque sensor and an electric power steering apparatus that are easy to manufacture, have high measurement accuracy, and are less likely to be damaged.

  In order to solve such a problem, in the present invention, in the torque sensor, an elastic member connected coaxially between the first and second shafts and the first shaft or one end side of the elastic member are fixed. A plurality of claw portions are provided in parallel with the magnet in the axial direction and in parallel with the magnet in the axial direction so as to face the peripheral side surface of the magnet, and the claw portions are alternately positioned. As described above, a pair of magnet side magnetic bodies fixed to both ends of the magnet in the axial direction, and the second shaft or the other end side of the elastic member are coupled to the magnet and the pair of magnet side magnetic bodies. Forming a circuit and having a structure in which a magnetic flux density generated in the magnetic circuit changes when a relative position between the pair of magnet-side magnetic bodies changes according to the twist of the elastic member; Detecting the magnetic flux density generated in the magnetic circuit Characterized in that it comprises a detection device.

  This makes it easy to magnetize one of the magnets in the axial direction to the N pole and the other to the S pole, making it easy to magnetize and reducing the number of magnetizing steps. And the magnetization accuracy can be improved. Moreover, since it is not necessary to provide opposing parts on the outer peripheral surface of the magnet, the surface of the magnet can be protected with a protective layer. As a result, problems such as magnet breakage can be improved, and reliability can be improved.

  According to a second aspect of the present invention, the magnetic body portion is composed of a pair of magnetic bodies arranged so as to face each other with an interval therebetween in the axial direction, and each of the magnetic bodies surrounds the magnet-side magnetic body. An annular annular portion disposed so as to surround, and a convex portion provided on the inner peripheral side of the annular portion so as to project in the radial direction of the annular portion, and between the convex portions of one of the magnetic bodies Each of the magnetic bodies is disposed so that the convex portion of the other magnetic body is located. Thereby, a magnetic circuit can be comprised with both the magnet side magnetic bodies, and the direction of the magnetic flux induced | guided | derived to a magnetic detection element can be reversed.

  According to a third aspect of the present invention, the pair of magnetic bodies are arranged such that the center of the convex portion of the other magnetic body is located at the center position between the convex portions of the one magnetic body. It is characterized by. Thereby, the circumferential distance of the convex part of one magnetic body and the convex part of the other magnetic body can be taken large.

  The invention according to claim 4 is characterized in that the convex portions of the magnetic body are provided at equal intervals. Thereby, the distance between the convex parts of a magnetic body can be taken large.

  The invention according to claim 5 is characterized in that the magnetic body has an axisymmetric shape. Thereby, since the convex part of a magnetic body is arrange | positioned in the symmetrical position with respect to an axis | shaft, the influence of eccentricity etc. can be made small.

  The invention according to claim 6 is characterized in that the pair of magnet-side magnetic bodies covers the entire magnetized surface of the magnet. Thereby, the magnetic flux generated from the magnet can be guided to the magnetic circuit without leakage.

  The invention according to claim 7 is such that the pair of magnet side magnetic bodies is located at the center position between the claw parts of one of the magnet side magnetic bodies and the center of the claw part of the other magnet side magnetic body is located. It is characterized by being arranged in. Thereby, the circumferential direction distance of the nail | claw part of one magnet side magnetic body and the claw part of the other magnet side magnetic body can be taken large.

  The invention according to claim 8 is characterized in that the magnet side magnetic body has an axisymmetric shape. Thereby, since the nail | claw part of a magnet side magnetic body is arrange | positioned in the symmetrical position with respect to an axis | shaft, the influence of eccentricity etc. can be made small.

  The invention according to claim 9 is characterized in that the claw portions of the magnet side magnetic body are arranged at equal intervals. Thereby, the distance between the nail | claw part of a magnet side magnetic body and a nail | claw part can be taken large.

  The invention according to claim 10 is characterized in that at least one of the magnet side magnetic body and the magnetic body is formed using an alloy having a nickel content of 40 wt% or more. Thereby, the magnetic characteristics of the magnet side magnetic body and the magnetic body can be improved.

  The invention according to claim 11 is characterized in that at least one of the magnet side magnetic body and the magnetic body is formed using an alloy having a nickel content of 40 wt% or more and 80 wt% or less. Thereby, the magnetic characteristics of the magnet side magnetic body and the magnetic body can be further improved.

  The invention according to claim 12 constitutes the magnetic circuit together with the magnet, the pair of magnet-side magnetic bodies, and the magnetic body portion, and is arranged close to the magnetic body portion to guide a magnetic flux from the magnetic body. An auxiliary magnetic body portion having a magnetic flux collecting portion for collecting the magnetic flux, and the magnetic detection element detects a magnetic flux density of the magnetic flux passing through the magnetic circuit collected in the magnetic flux collecting portion of the auxiliary magnetic body portion It is characterized by doing. As a result, even if the positional relationship between the magnetic detection element and the magnetic body changes, the influence on the magnetic circuit can be reduced and the magnetic flux can be concentrated on the magnetic detection element. Can be made small and strong against magnetic disturbance.

  According to a thirteenth aspect of the present invention, the magnetic body portion is composed of a pair of annular magnetic bodies arranged so as to face each other at an interval in the axial direction, and each of the auxiliary magnetic body portions corresponds to the corresponding magnetic material. And a pair of ring-shaped auxiliary magnetic bodies which are opposed to the body in the radial direction and whose axial dimension is larger than the axial dimension of the magnetic body. Thereby, the influence of the processing error of a component can be made small, and the influence of eccentricity etc. can be made small.

  According to a fourteenth aspect of the present invention, the magnetic body portion includes a pair of annular magnetic bodies disposed so as to face each other at an interval in the axial direction, and each of the auxiliary magnetic body portions corresponds to the corresponding magnetic material. And a pair of auxiliary magnetic bodies that are opposed to the body in the radial direction and sandwich the magnetic body in the axial direction. Thereby, the influence of the processing error of a component can be made small, and the influence of eccentricity etc. can be made small.

  According to a fifteenth aspect of the present invention, the magnetic body portion includes a pair of annular magnetic bodies disposed so as to face each other at an interval in the axial direction, and each of the auxiliary magnetic body portions corresponds to the corresponding magnetic material. It is characterized by comprising a pair of auxiliary magnetic bodies which are opposed to the body in the axial direction and have arc portions having a smaller width than the magnetic body. Thereby, the influence of the processing error of a component can be made small, and the influence of eccentricity etc. can be made small.

  The invention according to claim 16 is characterized in that the auxiliary magnetic body is formed using an alloy having a nickel content of 40 wt% or more. Thereby, the magnetic characteristics of the auxiliary magnetic body can be improved.

  The invention according to claim 17 is characterized in that the auxiliary magnetic body is formed using an alloy having a nickel content of 40 wt% or more and 80 wt% or less. Thereby, the magnetic characteristics of the auxiliary magnetic body can be further improved.

  The invention according to claim 18 is provided with an abnormality detection circuit provided with two of the magnetic detection elements and detecting an abnormality of the other magnetic detection element based on an output of the one magnetic detection element. . Thereby, a double system can be constituted.

  The invention according to claim 19 is characterized in that three or more magnetic detection elements are provided. Thereby, a multiplex system can be configured.

  An invention according to claim 20 is an electric power steering apparatus, comprising the torque sensor according to any one of claims 1 to 19. Thereby, highly accurate assist can be performed.

  According to the present invention, since only one of the magnets in the axial direction is magnetized to the N pole and the other is magnetized to the S pole, the magnetizing is easy and the number of magnetizing steps can be reduced. Variations in strength are reduced, and magnetization accuracy can be improved. Moreover, since it is not necessary to provide opposing parts on the outer peripheral surface of the magnet, the surface of the magnet can be protected with a protective layer. As a result, problems such as magnet breakage can be improved, and reliability can be improved.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  In FIG. 1 to FIG. 3, reference numeral 1 denotes a luc sensor 1 according to the present embodiment as a whole. The torque sensor 1 includes a torsion bar 4 that coaxially connects the first shaft 2 and the second shaft 3, a columnar magnet assembly 5 fixed to the lower end portion of the first shaft 2, and a magnet assembly 5. The magnetic body portion 6 is disposed so as to surround the periphery of the magnetic body portion, the auxiliary magnetic body portion 7 is disposed in the vicinity of the magnetic body portion and guides the magnetic flux from the magnetic body portion 6, and the magnetic detection element 8.

  The torsion bar 4 is a torsion element that twists itself when a relative torsion torque is applied between the first and second shafts 2 and 3, and is formed of an elastic member. In the case of the present embodiment, the torsion bar 4 is formed with a smaller diameter than the first and second shafts 2 and 3 so as not to interfere with the rotation of the magnet assembly 5 twisted integrally with the first shaft 2. Has been.

  The magnet assembly 5 is configured by integrally molding a magnet 10 and first and second magnet side magnetic bodies 11A and 11B made of a general iron metal with a resin 12. From the viewpoint of cost, a sintered ferrite magnet may be used as the magnet 10. In this case, it is conceivable that the magnet 10 is broken and a magnetic circuit described later is short-circuited. In the present embodiment, such a problem can be avoided by molding the magnetic assembly 5.

  The magnet 10 is formed in a columnar shape, and the upper surface side and the lower surface side thereof are respectively magnetized to an N pole or an S pole.

  Further, as is apparent from FIG. 3, the first and second magnet-side magnetic bodies 11A and 11B include a plurality of claw portions 11AY and 11BY at regular intervals on the outer peripheral portion of the perforated disk-shaped main plate portions 11AX and 11BX. The claw portions 11AY and 11BY are bent in the axial direction so as to face the peripheral side surface of the magnet 10 with a gap therebetween. In the case of the present embodiment, the first and second magnet-side magnetic bodies 11A and 11B have claw portions 11AY and 11BY having the same shape as the axial length of the magnet 10 at 60 ° intervals. Is provided.

  The first and second magnet-side magnetic bodies 11A and 11B are arranged so as to cover the magnet 10 from the upper surface side or the lower surface side and at the center position between the claw portions 11AY of the first magnet-side magnetic body 11A. The two magnet side magnetic bodies 11B are integrated with the resin 12 in a state where the claws 11BY are positioned so as to be positioned.

  On the other hand, the magnetic body portion 6 is composed of a pair of annular magnetic bodies 6A and 6B arranged to face each other with an interval in the axial direction. Each magnetic body 6A, 6B is made of a general iron-based metal, and includes annular portions 6AX, 6BX and rectangular convex portions 6AY, 6BY, respectively. The annular portions 6 </ b> AX and 6 </ b> BX have an inner diameter larger than the outer diameter of the magnet assembly 5, and are arranged so as to surround the magnet assembly 5 on the same axis as the magnet assembly 5. Further, the convex portions 6AY, 6BY are connected to the claw portions 11AY, 11BY of the first and second magnet side magnetic bodies 11A, 11B so as to protrude in the radial direction of the annular portions on the inner peripheral side of the annular portions 6AX, 6BX. The same number is provided at equal intervals.

  The first and second magnetic bodies 6A and 6B are resin in a state where the convex portions 6BY of the second magnetic body 6B are positioned at the center position between the convex portions 6AY of the first magnetic body 6A. 13 is integrated. The first and second magnetic bodies 6A and 6B are fixed to the second shaft 3 via the connecting member 14.

  On the other hand, the auxiliary magnetic body portion 7 includes first and second auxiliary magnetic bodies 7A and 7B each made of a general iron-based metal.

  The first and second auxiliary magnetic bodies 7A and 7B are formed in a ring shape in which the dimension in the axial direction is larger than the dimension in the axial direction of the first and second magnetic bodies 6A and 6B. The first and second magnetic bodies 6A and 6B are arranged so as to correspond to the radial direction with a gap therebetween.

  The first and second auxiliary magnetic bodies 7A and 7B are provided with magnetic flux collecting portions 7AX and 7BX projecting in the radial direction of the first or second auxiliary magnetic bodies 7A and 7B, respectively, on the outer peripheral side. The first and second auxiliary magnetic bodies 7A and 7B are molded with a resin 15 integrally with the magnetic detection element 8 so that the magnetic collecting portions 7AX and 7BX are opposed to each other with a gap therebetween. As a result, the magnetic flux passing through the magnetic circuit including the magnet 10, the first and second magnet side magnetic bodies 11A and 11B, the magnetic body 6, and the first and second auxiliary magnetic bodies 7A and 7B is converted into the first and second magnetic fluxes. The auxiliary magnetic bodies 7A and 7B can be collected between the magnetic collecting portions 7AX and 7AY.

  The magnetic detection element 8 includes a Hall element, an MR element, an MI element, and an IC using each. The magnetic detection element 8 is disposed between the magnetic flux collectors 7AX and 7BX of the first and second auxiliary magnetic bodies 7A and 7B, thereby detecting a change in magnetic flux density passing through the magnetic circuit. It has been made possible.

  In the torque sensor 1 having the above configuration, when a torsional torque is applied to the first shaft 2 and the torsion bar 4 is twisted, the circumference of the magnet assembly 5 and the first and second magnetic bodies 6A and 6B is increased. Since the relative angle (relative position) of the direction changes, the claw portions 11AX, 11BX of the first and second magnet side magnetic bodies 11A, 11B and the convex portions 6AY of the first and second magnetic bodies 6A, 6B, The distance from 6BY changes, and the amount of magnetic flux (magnetic flux density) flowing through the magnetic circuit changes accordingly.

  More specifically, when the relative rotation angle between the magnet assembly 5 and the first and second magnetic bodies 6A and 6B changes, for example, the claw portion 11AY of the first magnet side magnetic body 11A and the second magnet side The convex portion 6AY of the first magnetic body 6A located at the center between the claw portion 11BY of the magnetic body 11B is the first magnet side magnetic body 11A that is gradually on the N pole side (or S pole side). Away from the claw portion 11AY (or the claw portion 11BY of the second magnet side magnetic body 11B) and the claw portion 11BY of the second magnet side magnetic body 11B on the S pole side (or N pole side) The magnet side magnetic body 11A approaches the claw portion 11AY). At the same time, the convex portion 6BY of the second magnetic body 6B gradually becomes the claw portion 11BY (or the first magnet-side magnetic body 11A) of the second magnet-side magnetic body 11B that is on the S-pole side (or N-pole side). Away from the claw portion 11AY) and approaching the claw portion 11AY of the first magnet side magnetic body 11A on the N pole side (or S pole side) (or the claw portion 11BY of the second magnet side magnetic body 11B). Go. As a result, the amount of magnetic flux flowing from the first magnetic body 6A to the second magnetic body 6B gradually decreases, and finally the direction of the magnetic flux is reversed.

  FIG. 4 shows a state in which the convex portion 6AY of the first magnetic body 6A is positioned at the center between the claw portions 11AY of the first magnet-side magnetic body 11A and the claw portions 11BY of the second magnet-side magnetic body 11B (hereinafter referred to as “the projections 6AY”). This is referred to as a first state). In this first state, the convex portion 6BY of the second magnetic body 6B is also centered between the claw portions 11AY of the first magnet side magnetic body 11A and the claw portions 11BY of the second magnet side magnetic body 11B, respectively. Therefore, no magnetic flux flows in the magnetic circuit. The torque sensor 1 is in the first state when it is in an initial state in which a torsional torque is not applied to the first shaft 2 and the second shaft 3 from the outside.

  On the other hand, FIG. 5 shows that the first shaft 2 and / or the second shaft 3 are given a torsional torque from the first state, and the first and second magnetic bodies 6A and 6B are relative to the magnet assembly 5. A state of being rotated clockwise by 30 degrees is shown (hereinafter referred to as a second state). In this second state, the convex portions 6AY of the first magnetic body 6A are opposed to the claw portions 11AY of the first magnet-side magnetic body 11A, respectively, and the convex portions 6BY of the second magnetic body 6B are respectively second It faces the claw portion 11BY of the magnet side magnetic body 11B. In the second state, the convex portions 6AY of the first magnetic body 6A are respectively the claw portions 11AY of the first magnet-side magnetic body 11A, and the convex portions 6BY of the second magnetic body 6B are the second magnets. Since the claw portions 11BY of the side magnetic body 11B are closest to each other, the magnetic flux flows in the magnetic circuit from the claw portions 11AY of the first magnet side magnetic body 11A to the convex portions 6AY of the first magnetic body 6A.

  On the other hand, FIG. 6 shows that the torsional torque is applied to the first shaft 2 and / or the second shaft 3 from the first state, so that the first and second magnetic bodies 6A and 6B are relative to the magnet assembly 5. Specifically, it shows a state rotated 30 degrees counterclockwise (hereinafter referred to as a third state). In this third state, the convex portion 6AY of the first magnetic body 6A faces the claw portion 11BY of the second magnet-side magnetic body 11B, and the convex portion 6BY of the second magnetic body 6B is on the first magnet side. It is in a state facing the claw portion 11AY of the magnetic body 11A. In the third state, the convex portion 6AY of the first magnetic body 6A is on the claw portion 11BY of the second magnet side magnetic body 11B, and the convex portion 6BY of the second magnetic body 6B is on the first magnet side. Since the claw portions 11AY of the magnetic body 11A are closest to each other, the magnetic flux flows through the magnetic circuit from the claw portions 11AY of the first magnet-side magnetic body 11A to the convex portions 6BY of the second magnetic body 6B.

  FIG. 7 shows the output of the magnetic detection element 8 in the first to third states of FIGS. As shown in FIG. 7, when the relative angle between the magnet assembly 5 and the first and second magnetic bodies 6A and 6B changes, the direction and amount of the magnetic flux flowing through the magnetic circuit changes. By detecting the amount by the magnetic detection element 8, the relative rotation angle between the magnet assembly 5 and the first and second magnetic bodies 6A and 6B can be measured based on the detection result. As a result, the relative torsion amount of the first shaft 2 and the second shaft 3 can be measured, and the torsional torque applied to the first shaft 2 and the second shaft 3 from the torsional rigidity of the torsion bar 4 is large. Can be detected.

  When the torque sensor 1 according to the present embodiment is provided in the electric power steering apparatus, the steering shaft that is the first shaft 2, the output shaft that is the second shaft 3, the magnet assembly 5, the first and second shafts. The magnetic bodies 11A and 11B also rotate absolutely while relatively rotating. However, since the first and second auxiliary magnetic bodies 7A and 7B can be provided on the stationary side, a change in magnetic flux can be accurately measured.

  As described above, in the torque sensor 1 according to the present embodiment, the magnet 10 is simply magnetized with one of the N-poles in the axial direction and the other with the S-poles. In addition to the reduction, variation in magnetization intensity can be reduced, and the magnetization accuracy can be improved. Further, since it is not necessary to provide a component that contacts the outer peripheral surface of the magnet 10, the surface of the magnet 10 can be protected with a protective layer. As a result, problems such as breakage of the magnet 10 can be improved, and reliability can be improved.

  In the torque sensor 1 according to the present embodiment, the first and second auxiliary magnetic bodies 7A and 7B that guide the magnetic flux from the first and second magnetic bodies 6A and 6B are provided. Even when a change occurs in the positional relationship between the first magnetic body 6A and the second magnetic body 6B, the influence of the change on the magnetic circuit can be reduced. Further, in the torque sensor 1 according to the present embodiment, the magnetic detection element 8 is arranged between the magnetic collecting portions 7AX and 7BX provided in the first and second auxiliary magnetic bodies 7A and 7B. In addition to being able to concentrate on the magnetic detection element 8, it is possible to reduce the influence of eccentricity and the like, and to be strong against magnetic disturbance.

  Furthermore, in the torque sensor 1 according to the present embodiment, the axial dimension of the first and second auxiliary magnetic bodies 7A and 7B is selected to be longer than the axial dimension of the first and second magnetic bodies 6A and 6B. Therefore, the influence of the processing error of the component parts can be further reduced, and the influence of eccentricity can be reduced.

  Further, in the torque sensor 1 according to the present embodiment, since the entire magnetized surface of the magnet 10 is covered by the first and second magnet-side magnetic bodies 11A and 11B, the magnetic flux generated from the magnet 10 can be magnetized without leakage. Can be directed to the circuit.

  Furthermore, in the torque sensor 1 according to the present embodiment, the first center is located so that the center of the claw part 11BY of the second magnet side magnetic body 11B is located at the center position between the claw parts 11AY of the first magnet side magnetic body 11A. Since the second magnet side magnetic bodies 11A and 11B are positioned, the distance between the claw portions 11AY of the first magnet side magnetic body 11A and the distance between the claw portions 11BY of the second magnet side magnetic body 11B is increased. Thus, the detection range of the twist angle can be increased. Similarly, the first and second magnetic bodies 6A and 6B are positioned so that the center of the convex portion 6BY of the second magnetic body 6B is positioned at the center position between the convex portions 6AY of the first magnetic body 6A. Therefore, the distance between the convex portions 6AY of the first magnetic body 6A and the convex portion 6BY of the second magnetic body 6B can be increased, and the detection range of the twist angle can be increased.

  Furthermore, in the torque sensor 1 according to the present embodiment, since the claw portions 11AY and 11BY of the first and second magnet-side magnetic bodies 11A and 11B are arranged at equal intervals, the distance between the claw portions 11AY and 11BY. The torsion angle detection range can be increased. Similarly, since the convex portions 6AY and 6BY of the first and second magnetic bodies 6A and 6B are arranged at equal intervals, the distance between the convex portions 6AY and 6BY can be increased, and the twist angle can be detected. The range can be increased.

  Furthermore, in the torque sensor 1 according to the present embodiment, the first and second magnet-side magnetic bodies 11A and 11B are formed in an axisymmetric shape, so that the influence of eccentricity and the like can be reduced. Similarly, since the first and second magnetic bodies 6A and 6B are also formed in an axisymmetric shape, the influence of eccentricity or the like can be reduced.

  Furthermore, if this torque sensor 1 is provided in an electric power steering apparatus, an electric power steering apparatus capable of highly accurate assist can be obtained.

(2) Second Embodiment FIGS. 8 and 9 show a schematic configuration of a torque sensor 20 according to a second embodiment. The torque sensor 20 is configured in the same manner as the torque sensor 1 according to the first embodiment except that the structure of the auxiliary magnetic body portion 21 is different.

  That is, in the case of the present embodiment, the auxiliary magnetic body portion 21 is composed of first and second auxiliary magnetic bodies 21A and 21B made of a general metal such as iron. The first and second auxiliary magnetic bodies 21A, 21B are plate-like arc portions 21AX, 21BX having the same arc shape as the first and second magnetic bodies 6A, 6B, and the arc portions 21AX, 21BX. The sandwiched portions 21AY and 21BY having a U-shaped cross section formed so as to open radially inward of the circular arc portions 21AX and 21BX at both ends in the circumferential direction, and the substantially central portion in the circumferential direction of the circular arc portions 21AX and 21BX Are provided with magnetic flux collecting portions 21AZ, 21BZ formed so as to protrude radially outward of the arc portions 21AX, 21BX. The arc portions 21AX and 21BX, the sandwiching portions 21AY and 21BY, and the magnetism collecting portions 21AZ and 21BZ are formed by bending a plate having a predetermined shape made of an iron-based metal.

  The first and second auxiliary magnetic bodies 21A and 21B are attached to the corresponding first or second magnetic bodies 6A and 6B from the outside in the radial direction so as to be sandwiched between the sandwiching portions 21AY and 21BY in the axial direction. ing. Further, the magnetic detection element 8 is disposed between the magnetic collecting portions 21AZ and 21BZ of the first and second auxiliary magnetic bodies 21A and 21B, and the first and second auxiliary magnetic bodies 21A and 21B and the magnetic detection element are arranged. 8 is integrally molded with a resin (not shown).

  As described above, in the torque sensor 20 according to the present embodiment, the first and second auxiliary magnetic bodies 21A and 21B have diameters corresponding to the first and second magnetic bodies 6A and 6B corresponding to the sandwiching portions 21AY and 21BY. By being configured so as to be opposed to each other and sandwiched in the axial direction, it is possible to reduce the influence of machining errors of components and reduce the influence of eccentricity and the like. Therefore, the influence on the magnetic circuit can be reduced even when subjected to a mechanical disturbance.

(3) Third Embodiment FIGS. 10 to 12 show a schematic configuration of a torque sensor 30 according to a third embodiment. The torque sensor 30 is configured in the same manner as the torque sensor 1 according to the first embodiment except that the configuration of the auxiliary magnetic body portion 31 is different.

  That is, in the case of the present embodiment, the auxiliary magnetic body portion 31 is composed of first and second auxiliary magnetic bodies 31A and 31B made of a general metal such as iron. The first and second auxiliary magnetic bodies 31A and 31B include arc portions 31AX and 31BX having arc shapes substantially the same diameter as the first and second magnetic bodies 6A and 6B, and the circumferential direction of the arc portions 31AX and 31BX. Magnetic flux collecting portions 31AY, 31BY formed so as to protrude radially outward of the arc portions 31AX, 31BX. The arc portions 31AX and 31BX and the magnetism collecting portions 31AY and 31BY are formed by bending a plate having a predetermined shape made of an iron-based metal.

  In this case, the first and second auxiliary magnetic bodies 31A and 31B are formed such that the width of the arc portions 31AX and 31BX is smaller than the width of the annular portions 6AX and 6BX of the first and second magnetic bodies 6A and 6B. And the inner side surface between the first and second magnetic bodies 6A and 6B to which the arc portions 31AX and 31BX correspond (the second or second of the opposite side to which the first or second magnetic bodies 6A and 6B form a pair). 1 magnetic bodies 6B, 6A) and the axial direction.

  Thus, the torque sensor 30 according to the present embodiment has the arc portions 31AX, 31AX, 31B of the first and second auxiliary magnetic bodies 31A, 31B based on the widths of the annular portions 6AX, 6BX of the first and second magnetic bodies 6A, 6B. Since the width of 31BX is reduced, it is possible to reduce the influence of processing errors of components and to reduce the influence of eccentricity and the like. Therefore, the influence on the magnetic circuit can be reduced even when subjected to a mechanical disturbance.

(4) Other Embodiments In the first to third embodiments described above, the convex portions 6AY and 6BY of the first and second magnetic bodies 6A and 6B are formed in a rectangular shape. However, the present invention is not limited to this, and the shape of the convex portions 6AY and 6BY may be a triangle, an arc shape, or the like. Various shapes can be widely applied as the shapes of the portions 6AY and 6BY.

  In the first to third embodiments, the first and second magnet side magnetic bodies 11A and 11B, the first and second magnetic bodies 6A and 6B, and the first and second auxiliary magnetic bodies are used. Although the case where 7A, 7B, 21A, 21B, 31A, 31B is formed of a general iron-based metal has been described, the present invention is not limited to this, and at least one of these is iron-based. You may make it form using magnetic materials other than. Specifically, when a general iron-based metal is used as the material of the first and second magnetic bodies 6A, 6B, etc., hysteresis occurs in the output characteristics of the first and second magnetic bodies 6A, 6B. To do. Therefore, by using an alloy containing nickel as such a material, the first and second magnet-side magnetic bodies 11A and 11B, the first and second magnetic bodies 6A and 6B, and the first and second auxiliary magnetisms are used. The magnetic properties of the bodies 7A, 7B, 21A, 21B, 31A, 31B can be improved.

  In this case, by using an alloy containing nickel of 40% (40 wt%) or more of the total weight as such a material, hysteresis is remarkably reduced as compared with general iron-based metals. Although it can be improved to a satisfactory level, it cannot be completely eliminated. Therefore, when it is desired to further reduce the hysteresis, an alloy containing nickel of 40% or more and 80% or less (40 wt% or more and 80 wt% or less), more preferably 70% (70 wt%) or more of the total weight as such a material. It should be used. Thereby, the magnetic characteristics of the first and second magnet side magnetic bodies 11A, 11B and the like can be further improved. However, since nickel is expensive, the content of nickel is preferably selected according to the required performance.

  Furthermore, in the above-described first to third embodiments, the case where only one magnetic detection element 8 is used has been described. However, the present invention is not limited to this, and two magnetic detection elements 8 are used. You may do it. Thereby, a double system can be constituted. In that case, by setting the output characteristics of the two magnetic detection elements 8 in opposite directions and obtaining the differential between the two magnetic detection elements 8, the sensitivity can be improved by a factor of two. If the sensitivity is sufficient, it is not necessary to obtain a differential between the two magnetic detection elements 8, and either one of the output signals may be used. In this case, the output characteristics of the two magnetic detection elements 8 may be the same. When only the output signal of one magnetic detection element 8 out of the two magnetic detection elements 8 is used, the output signal of the other magnetic detection element 8 is used as a reference to detect abnormality of the magnetic detection element 8. Can be used. Specifically, an abnormality detection circuit that detects an abnormality of the other magnetic detection element based on the output of one magnetic detection element 8 is provided, and when the abnormality detection circuit detects an abnormality of the one magnetic detection element 8, Report the error to the user.

  In addition, when there are two magnetic detection elements 8 and one of the magnetic detection elements 8 is damaged, it cannot be determined which of the magnetic detection elements 8 is damaged. Therefore, by arranging three or more magnetic detection elements 8 to form a multiplex system, it is possible to determine that the output signal with the larger number of matching output characteristics is correct, so that the damaged magnetic detection element 8 can be identified. As a result, even if one magnetic detection element 8 is damaged, the normal magnetic detection element 8 can be specified. Therefore, the output signal can be used without any problem. In addition, when using the some magnetic detection element 8, if the dedicated power supply is installed in each, the reliability of the whole torque sensor can be improved further.

  Further, in the above-described first to third embodiments, the case where the first and second magnetic bodies 6A and 6B are fixed to the second shaft 3 has been described, but the present invention is not limited thereto. Instead, the first and second magnetic bodies 6A and 6B may be coupled to the end of the torsion bar 4 on the second shaft 3 side.

  Further, in the first to third embodiments described above, the convex portions 6AY and 6BY of the first and second magnetic bodies 6A and 6B and the claw portion 11AY of the first and second magnet-side magnetic bodies 11A and 11B. However, the present invention is not limited to this, and other numbers may be provided.

  Further, in the above-described third embodiment, the first and second auxiliary magnetic bodies 31A and 31B are attached to the axial inner surfaces of the corresponding first or second magnetic bodies 6A and 6B. However, the present invention is not limited to this, and the first and second auxiliary magnetic bodies 31A and 31B are configured so that the arc portions 31AX and 31BX are the outer surfaces (the inner surface and the inner surface) of the first or second magnetic bodies 6A and 6B. You may make it arrange | position so that it may oppose the surface which opposes an axial direction.

It is sectional drawing which shows schematic structure of the torque sensor by 1st Embodiment. It is a perspective view which shows schematic structure of the torque sensor by 1st Embodiment. It is a disassembled perspective view which shows schematic structure of the torque sensor by 1st Embodiment. It is a top view with which it uses for operation | movement description of the torque sensor by 1st Embodiment. It is a top view with which it uses for operation | movement description of the torque sensor by 1st Embodiment. It is a top view with which it uses for operation | movement description of the torque sensor by 1st Embodiment. It is a characteristic diagram which shows the output voltage in each state of the torque sensor by 1st Embodiment. It is a perspective view which shows schematic structure of the torque sensor by 2nd Embodiment. It is a disassembled perspective view with which it uses for description of the auxiliary | assistant magnetic body part of the torque sensor by 2nd Embodiment. It is a perspective view which shows schematic structure of the torque sensor by 3rd Embodiment. It is a disassembled perspective view with which it uses for description of the auxiliary | assistant magnetic body part of the torque sensor by 3rd Embodiment. It is a top view with which it uses for description of the positional relationship of the auxiliary magnetic body and magnetic body of a torque sensor by 3rd Embodiment.

Explanation of symbols

  1, 20, 30 ... Torque sensor, 2 ... First axis, 3 ... Second axis, 4 ... Torsion bar, 5 ... Magnet assembly, 6 ... Magnetic body, 6A, 6B ... Magnetic body, 6AY, 6BY ... convex part, 7, 21, 31 ... auxiliary magnetic body part, 7A, 7B, 21A, 21B, 31A, 31B ... auxiliary magnetic body, 7AX, 7BX, 21AZ, 21BZ, 31AY, 31BY: Magnetic collector, 10: Magnet, 11A, 11B: Magnet side magnetic body, 11AY, 11BY: Claw, 8: Magnetic detection element.

Claims (20)

An elastic member coaxially connected between the first and second shafts;
A magnet fixed to one end of the first shaft or the elastic member and magnetized in two axial directions;
A plurality of claw portions are provided so as to face the circumferential side surface of the magnet and parallel to the axial direction of the magnet, and are fixed to both ends of the magnet in the axial direction so that the claw portions are alternately positioned. A pair of magnet side magnetic bodies;
The second shaft or the other end side of the elastic member is connected to form a magnetic circuit together with the magnet and the pair of magnet side magnetic bodies, and the pair of magnet side magnetic bodies according to the twist of the elastic member A magnetic part having a structure in which the magnetic flux density generated in the magnetic circuit changes when the relative position between
A torque sensor comprising: a magnetic detection element that detects a magnetic flux density generated in the magnetic circuit. The magnetic part is
It is composed of a set of magnetic bodies arranged so as to face each other at an interval in the axial direction,
Each of the magnetic bodies
An annular portion disposed so as to surround the magnet-side magnetic body;
A convex portion provided on the inner peripheral side of the annular portion so as to protrude in the radial direction of the annular portion,
2. The torque sensor according to claim 1, wherein each of the magnetic bodies is disposed so that the convex portion of the other magnetic body is positioned between the convex portions of one of the magnetic bodies. The set of magnetic bodies is
The torque sensor according to claim 2, wherein the torque sensor is disposed such that the center of the convex portion of the other magnetic body is positioned at the center position between the convex portions of the one magnetic body. The torque sensor according to claim 2 or 3, wherein the magnetic body has the convex portions provided at equal intervals. The torque sensor according to any one of claims 2 to 4, wherein the magnetic body has an axisymmetric shape. The torque sensor according to any one of claims 1 to 5, wherein the pair of magnet-side magnetic bodies covers the entire magnetized surface of the magnet. The pair of magnet-side magnetic bodies is
The center of the claw part of the other said magnet side magnetic body is arrange | positioned in the center position between the said claw parts of one said magnet side magnetic body, The 1st thru | or 6 characterized by the above-mentioned. The torque sensor according to any one of the above. The torque sensor according to any one of claims 1 to 7, wherein the magnet-side magnetic body has an axisymmetric shape. The torque sensor according to any one of claims 1 to 8, wherein the magnet side magnetic body has claw portions arranged at equal intervals. At least one of the magnet-side magnetic body and the magnetic body is
The torque sensor according to any one of claims 1 to 9, wherein the torque sensor is formed using an alloy having a nickel content of 40 wt% or more. At least one of the magnet-side magnetic body and the magnetic body is
The torque sensor according to any one of claims 1 to 9, wherein the torque sensor is formed using an alloy having a nickel content of 40 wt% or more and 80 wt% or less. The magnet, the pair of magnet-side magnetic bodies, and the magnetic body portion constitute the magnetic circuit, and are arranged close to the magnetic body portion to guide the magnetic flux from the magnetic body and collect the magnetic flux An auxiliary magnetic body having
The magnetic detection element is
The torque sensor according to any one of claims 1 to 11, wherein a magnetic flux density of the magnetic flux passing through the magnetic circuit collected at the magnetic collecting portion of the auxiliary magnetic body portion is detected. The magnetic part is
It is composed of a pair of annular magnetic bodies arranged so as to face each other with an interval in the axial direction,
The auxiliary magnetic body portion is
The torque according to claim 12, comprising a pair of ring-shaped auxiliary magnetic bodies that are opposed to the corresponding magnetic bodies in the radial direction and whose axial dimensions are larger than the axial dimensions of the magnetic bodies. Sensor. The magnetic part is
It is composed of a pair of annular magnetic bodies arranged so as to face each other with an interval in the axial direction,
The auxiliary magnetic part is
The torque sensor according to claim 12, further comprising a pair of auxiliary magnetic bodies that are opposed to the corresponding magnetic bodies in the radial direction and sandwich the magnetic bodies in the axial direction. The magnetic part is
It is composed of a pair of annular magnetic bodies arranged so as to face each other with an interval in the axial direction,
The auxiliary magnetic part is
13. The torque sensor according to claim 12, comprising a pair of auxiliary magnetic bodies that are opposed to the corresponding magnetic bodies in the axial direction and have arc portions having a smaller width than the magnetic bodies. The torque sensor according to any one of claims 13 to 15, wherein the auxiliary magnetic body is formed using an alloy having a nickel content of 40 wt% or more. The torque sensor according to any one of claims 12 to 15, wherein the auxiliary magnetic body is formed using an alloy having a nickel content of 40 wt% to 80 wt%. Two magnetic sensing elements are provided;
The torque sensor according to any one of claims 1 to 17, further comprising an abnormality detection circuit that detects an abnormality of the other magnetic detection element based on an output of the one magnetic detection element. The torque sensor according to any one of claims 1 to 18, wherein three or more magnetic detection elements are provided. An electric power steering apparatus comprising the torque sensor according to any one of claims 1 to 19.