JP4997474B2 - Torque detection device - Google Patents

Description

  The present invention relates to a torque detection device that detects rotational torque applied to first and second shafts connected coaxially by a relative angular displacement generated between the first and second shafts.

  An electric power steering apparatus that drives a steering assist motor in response to a rotation operation of a steering member such as a steering wheel and transmits the rotational force of the motor to a steering mechanism to assist steering is provided by driving a steering assist motor. A torque detection device that detects a steering torque applied to the steering member for use in control is provided. In this torque detection device, a steering shaft (rotating shaft) that connects a steering member and a steering mechanism is divided into a first shaft and a second shaft that are coaxially connected by a torsion bar, and steering is performed by operating the steering member. A steering torque (rotational torque) applied to the shaft is detected using a relative angular displacement generated between the first shaft and the second shaft in accordance with torsion of the torsion bar.

  The relative angular displacement between the first and second axes is conventionally detected by various means, and one of them is a cylindrical magnet that rotates integrally with the first axis, and surrounds the cylindrical magnet, A yoke ring that rotates integrally with the second shaft, and is configured to detect the relative angular displacement using a change in magnetic flux density of a magnetic circuit formed between the cylindrical magnet and the yoke ring. There is a torque detection device (see, for example, Patent Document 1).

  The cylindrical magnet that rotates integrally with the first shaft is a multipolar magnet in which N and S magnetic poles are alternately arranged in the circumferential direction. The yoke ring that rotates integrally with the second shaft is made of a soft magnetic material in which the same number of magnetic pole claws as the pair of N and S poles are equally distributed in the circumferential direction on one end edge of the annular ring body. These thin rings are fixed to the second shaft as a set of two pieces that are positioned so that the magnetic pole claws are alternately arranged in the circumferential direction. A magnetic flux collecting ring for collecting magnetic flux generated in the yoke ring is provided so as to surround the outside of the yoke ring. The magnetism collecting ring is provided with magnetism collecting projections that extend in the axial length direction and are bent at the distal end in the radial direction at two locations separated by a suitable length in the circumferential direction, and the magnetism collecting projections face each other. It is arranged to do. Magnetic detecting means is disposed between the facing portions of the magnetic flux collecting projections, and the magnetic detecting means detects a change in the magnetic flux density of the magnetic circuit to obtain a relative angular displacement between the first axis and the second axis. The rotational torque is obtained from the obtained relative angular displacement.

In the torque detection device configured as described above, it is desirable to make the gap between the magnetic flux collection protrusion and the magnetic detection means as narrow as possible in order to detect a change in magnetic flux density with high accuracy. Therefore, conventionally, a configuration is adopted in which the magnetic detection means is sandwiched between the magnetic collection protrusions, and the magnetic collection ring and the magnetic detection means are integrated by a resin mold body molded with synthetic resin while maintaining this state. (For example, refer to Patent Document 2).
JP 2003-149062 A JP 2003-332511 A

  However, when the magnetism collecting ring and the magnetism detecting means are integrated in this way, it is necessary to replace the magnetism collecting ring together when the magnetism detecting means fails, and work such as removing the shaft from the magnetism detecting means. This requires a lot of time and labor for replacement, and increases costs.

  Although the problem can be solved by configuring the magnetic detection means to be inserted later between the magnetic flux collecting projections so that only the magnetic detection means can be replaced, it is possible to detect rotational torque with high accuracy. Thus, when the gap between the magnetic flux collecting projections and the magnetic detection means is narrowed, it is difficult to assemble the magnetic detection means, and it is necessary to manage with high accuracy in order to maintain the narrow gap, which increases the cost. there were. On the other hand, when the gap is widened so that it can be easily assembled, the magnetic flux leaking around increases, the magnetic flux passing through the magnetic detection means decreases, and the gap is further varied, resulting in a decrease in detection accuracy. there were.

The present invention has been made in view of such circumstances, and it is possible to easily assemble the magnetic detection means between the opposed portions of the magnetism collection ring while ensuring the detection accuracy of the rotational torque , and only the magnetic detection means. An object of the present invention is to provide a torque detection device that can be replaced.

In the torque detector according to the first aspect of the invention, a cylindrical magnet and two yoke rings are fixed to the first and second shafts connected coaxially, respectively, and in addition to the first and second shafts. By detecting a change in the magnetic flux generated in each of the yoke rings in accordance with the relative angular displacement caused by the action of the rotational torque generated by the magnetic detection means disposed between the opposing portions of the magnetism collecting rings that respectively surround the yoke rings. In the torque detection device configured to obtain the rotational torque, grease mixed with magnetic powder is interposed between a facing portion of the magnetism collecting ring and the magnetic detection means .

In the torque detection device according to the second aspect of the invention, a cylindrical magnet and two yoke rings are fixed to the first and second shafts connected coaxially, respectively, and in addition to the first and second shafts. By detecting a change in the magnetic flux generated in each of the yoke rings in accordance with the relative angular displacement caused by the action of the rotational torque generated by the magnetic detection means disposed between the opposing portions of the magnetism collecting rings that respectively surround the yoke rings In the torque detection device configured to obtain the rotational torque, a curable resin mixed with magnetic powder is interposed between a facing portion of the magnetism collecting ring and the magnetic detection means. .

In the torque detector according to the third aspect of the present invention, a cylindrical magnet and two yoke rings are fixed to the first and second shafts connected coaxially, respectively, and in addition to the first and second shafts. By detecting a change in the magnetic flux generated in each of the yoke rings in accordance with the relative angular displacement caused by the action of the rotational torque generated by the magnetic detection means disposed between the opposing portions of the magnetism collecting rings that respectively surround the yoke rings. in the rotation torque torque detecting device configured to determine a rubber obtained by mixing magnetic powder respectively mounted on opposing portions of the magnetic flux collecting rings, the rubber is inclined so as opposing surfaces are close to each other taper It has a surface and is elastically contacted with the magnetic detection means.

According to the first aspect of the invention, since the grease mixed with the magnetic powder is interposed between the facing portion of the magnetism collecting ring and the magnetic detection means , according to the relative angular displacement between the first axis and the second axis. The magnetic flux collected between the opposing portions of the magnetism collecting ring is concentrated on the magnetic detection means through the grease mixed with the magnetic powder, and the magnetic flux passing through the magnetic detection means increases. Therefore, the relative magnetic flux is increased based on the detection result of the magnetic detection means. By obtaining the angular displacement, it is possible to detect the rotational torque with high accuracy. Further, for example, the magnetic detecting means coated with the grease mixed with the magnetic powder can be easily inserted with the grease mixed with the magnetic powder by the procedure of inserting the magnetic detecting means between the opposing portions of the magnetic collecting ring. The gap between the facing portion and the magnetic detection means can be widened, and the magnetic detection means can be easily assembled .

According to the second invention, since the curable resin such as the thermosetting resin or the ultraviolet curable resin mixed with the magnetic powder is interposed between the facing portion of the magnetism collecting ring and the magnetic detection means , the first The magnetic flux collected between the opposing portions of the magnetism collecting ring according to the relative angular displacement between the shaft and the second shaft is concentrated on the magnetic detection means through the curable resin mixed with magnetic powder, and the magnetic flux passing through the magnetic detection means is Therefore, the rotational torque can be detected with high accuracy by obtaining the relative angular displacement based on the detection result of the magnetic detection means. In addition, for example, after magnetic detecting means coated with a curable resin mixed with magnetic powder is inserted between the opposing portions of the magnetism collecting ring , the magnetic powder is mixed by the procedure of curing the curable resin by heating or ultraviolet irradiation . Rutotomoni can easily be interposed curable resin, the magnetic flux collecting ring gap between the opposing portion and the magnetic detecting means able to be widely, assembling of the magnetic detection means becomes easy, after assembly The magnetic detection means can be extracted and exchanged. On the other hand, it is possible to maintain the holding state of the curable resin mixed with magnetic powder even in the use environment where the assembly becomes high temperature or vibration is applied, and it is possible to detect the rotational torque stably and accurately. Become.

According to the third invention, a rubber obtained by mixing magnetic powder, and respectively mounted on opposing portions of the magnetic flux collector rings, since is elastically contacted to the magnetic detection means, the relative angle between the first and second axes The magnetic flux collected between the opposing parts of the magnetism collecting ring according to the displacement concentrates on the magnetic detection means through the rubber mixed with the magnetic powder, and the magnetic flux passing through the magnetic detection means increases. By obtaining the relative angular displacement based on this, it is possible to detect the rotational torque with high accuracy. Further, by inserting the magnetic detection means between the rubbers using the opposed tapered surfaces of the rubber previously mounted on each magnetic collection ring as a guide, the gap between the opposing part of the magnetic collection ring and the magnetic detection means is increased. As a result, the magnetic detecting means with rubber can be easily assembled and the magnetic detecting means can be easily detached.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof. FIG. 1 is a longitudinal sectional view schematically showing an assembled state of a torque detection device according to the present invention, and FIG. 2 is an exploded perspective view of a main part of the torque detection device according to the present invention.

  The torque detection device according to the present invention detects rotation torque applied to two shafts (first shaft 1 and second shaft 2) connected by a torsion bar 3, and rotates integrally with the first shaft 1. And a pair of yoke rings 5a and 5b that rotate integrally with the second shaft 2, and the yoke rings 5a and 5b are arranged so as to surround the outer sides of the yoke rings 5a and 5b. , 5 b and magnetic flux collecting rings 6, 6 for collecting magnetic flux generated in the magnetic flux collecting rings 6, 6, and magnetic sensors 7, 7 disposed between the magnetic flux collecting rings 6, 6.

  The torsion bar 3 includes connecting portions 30 and 30 having large diameters for connecting the first and second shafts 1 and 2 to both ends of a small-diameter round bar as a torsion spring. The first shaft 1 and the second shaft 2 are respectively connected to the connecting holes 10 and 20 formed in the respective shaft center portions by fitting the connecting portions 30 and 30 provided at both ends of the torsion bar 3 respectively. The pins 11 and 21 are connected by driving.

  When rotational torque is applied to the first shaft 1 and the second shaft 2 connected in this manner, the torsion bar 3 is twisted and deformed by the action of the rotational torque, and the first shaft 1 and the second shaft 2 In the meantime, a relative angular displacement having a magnitude corresponding to the rotational torque occurs in the direction of the rotational torque.

  As shown in FIG. 2, the cylindrical magnet 4 that rotates integrally with the first shaft 1 is a multipolar magnet in which a plurality of N poles 40, 40... And S poles 41, 41. As shown in FIG. 1, it is coaxially fixed to the first shaft 1 via a resin molded body 42 that is molded so as to cover both end surfaces and the inner surface with an appropriate thickness. Yes.

  As shown in FIG. 2, the yoke rings 5 a and 5 b that rotate integrally with the second shaft 2 have a plurality of magnetic pole claws that form a triangle extending in the axial length direction on the inner peripheral edge of the annular yoke body 50 or 50. 51, 51... These yoke rings 5a, 5b are positioned so that the magnetic pole claws 51, 51,... Are alternately arranged in the circumferential direction, and are integrated by a cylindrical resin mold body 52. As shown in FIG. Is coaxially fixed to the second shaft 2 through a boss portion 53 formed by extending one side. In the yoke rings 5a and 5b as described above, the inner surfaces exposed on the inner surface of the resin mold body 52 face the outer peripheral surface of the cylindrical magnet 4 with a slight air gap therebetween. It is assembled so that a predetermined positional relationship is obtained in the direction and the circumferential direction.

  The magnetic flux collecting rings 6 and 6 that collect magnetic flux generated in the yoke rings 5a and 5b are annulus made of a magnetic material having an inner diameter slightly larger than the outer diameter of the yoke main bodies 50 and 50, and are separated by an appropriate length in the circumferential direction. Two magnetic flux collecting protrusions 60 and 60 are provided at two locations, which extend in the axial direction and are bent at the distal end in the radial direction. The magnetism collecting rings 6 and 6 are positioned so that the magnetism collecting projections 60 and 60 face each other at a predetermined air gap, and are integrated by a cylindrical resin mold body 61 as shown in FIG. It is fitted and fixed to the housing 8 partially shown in FIG.

  FIG. 3 is an explanatory diagram showing the positional relationship between the yoke rings 5 a and 5 b and the magnetic poles of the cylindrical magnet 4. FIG. 3B shows the positional relationship during assembly, and the yoke rings 5a and 5b and the cylindrical magnet 4 maintain the positional relationship such that they are aligned in the axial direction, and then the yoke ring 5a. , 5b are positioned in the circumferential direction so as to be positioned at the boundary between the N pole 40 and the S pole 41 of the cylindrical magnet 4, respectively. In this positional relationship, the areas facing the magnetic pole claws 51, 51... Of the yoke rings 5a, 5b are the same in the N pole 40 and the S pole 41 of the cylindrical magnet 4, and the magnetic flux entering from the N pole 40 and the S pole 41. Thus, no magnetic flux is generated between the yoke rings 5a and 5b.

  When a rotational torque in one direction is applied to the first shaft 1 or the second shaft 2, the torsion bar 3 is twisted, and the magnetic pole claws 51, 51... Of the yoke rings 5a, 5b and the N pole 40 of the cylindrical magnet 4. And the positional relationship of the circumferential direction with the S pole 41 changes. At this time, for example, as shown in FIG. 3A, the area facing the magnetic pole claws 51, 51... Of the yoke ring 5 a is larger in the N pole 40 than in the S pole 41 and enters from the N pole 40. The magnetic flux is larger than the magnetic flux exiting the S pole 41. Further, the area of the yoke ring 5b facing the magnetic pole claws 51, 51... Is smaller in the N pole 40 than in the S pole 41, and the magnetic flux entering from the N pole 40 is smaller than the magnetic flux exiting to the S pole 41. As a result, a magnetic flux is generated from the yoke ring 5a to the yoke ring 5b, and the magnetic flux density increases as the area difference between the N pole 40 and the S pole 41 opposed to the magnetic pole claws 51, 51.

  On the other hand, when rotational torque in the other direction is applied to the first shaft 1 or the second shaft 2, the torsion bar 3 is twisted in the opposite direction to the above, and the magnetic pole claws 51, 51 of the yoke rings 5a, 5b. ... and the circumferential positional relationship between the N pole 40 and the S pole 41 of the cylindrical magnet 4 change. At this time, for example, as shown in FIG. 3C, the area facing the magnetic pole claws 51, 51... Of the yoke ring 5 a is smaller in the N pole 40 than in the S pole 41 and enters from the N pole 40. The magnetic flux is smaller than the magnetic flux exiting the S pole 41. Further, the area of the yoke ring 5 b facing the magnetic pole claws 51, 51... Is larger in the N pole 40 than in the S pole 41, and the magnetic flux entering from the N pole 40 is larger than the magnetic flux going out to the S pole 41. As a result, a magnetic flux is generated from the yoke ring 5b to the yoke ring 5a, and the magnetic flux density increases as the difference between the areas of the N pole 40 and the S pole 41 facing the magnetic pole claws 51, 51.

  The magnetic flux generated in the yoke rings 5a and 5b in this way is guided to the magnetic flux collecting rings 6 and 6, gathers in the magnetic flux collecting projections 60 and 60, and leaks between the magnetic flux collecting projections 60 and 60. The density of the leaked magnetic flux is detected by the magnetic sensors 7 and 7 disposed between the opposing portions of the magnetic flux collecting projections 60 and 60. Using this detection result, the relative angular displacement between the first shaft 1 and the second shaft 2, that is, the rotational torque applied to the first shaft 1 and the second shaft 2 can be obtained.

  As shown in FIG. 1, the magnetic sensor 7 is attached to one end of a cylindrical holder 70. A flange portion 71 is provided around the middle portion of the holder 70.

  On the other hand, the housing 8 is provided with a mounting hole 80 for attaching the holder 70 so as to be aligned between the opposing portions of the magnetic flux collecting projections 60, 60 of the magnetic flux collecting rings 6, 6 held inside the housing 8. A seating surface 81 is formed so as to border the mounting hole 80. The holder 70 is inserted into the mounting hole 80 provided in the housing 8 with the projecting side of the magnetic sensor 7 facing inward, and the magnetic sensor 7 is secured to the seating surface 81 by screwing and fixing the flange portion 71 to the magnetic flux collecting projection. 60 and 60 are mounted on the housing 8 so as to be positioned between the opposing portions.

  4 is an enlarged view of the vicinity of the magnetic flux collecting projections 60, 60. FIG. 4 (a) shows a state before the magnetic sensor 7 is attached, and FIG. 4 (b) shows a state after the magnetic sensor 7 is attached. ing. The magnetic sensor 7 includes a detection unit 7a that is a Hall element that uses a Hall effect that a voltage is generated in a direction orthogonal to the direction of the magnetic field and the current when the direction of the current is bent by the magnetic field, and the output voltage of the detection unit 7a. This is a known Hall IC that is integrally provided with an amplification amplifier for amplification and is covered with an exterior material.

  As shown in FIG. 4 (b), the detecting portion 7a of the magnetic sensor 7 is located between the opposing portions of the magnetic flux collecting projections 60, 60, and the magnetic flux collecting projections 60, opposed to each other with the detecting portion 7a interposed therebetween. Between the opposed surfaces of the magnetic sensor 60 and the magnetic sensor 7, magnetic materials 9, 9 having magnetism are interposed.

  With the above configuration, the magnetic flux focused on the tips of the magnetic flux collecting projections 60 and 60 is guided to the magnetic sensor 7 through the magnetic materials 9 and 9. Since the magnetic materials 9 and 9 have magnetism, the magnetic flux focused on the tips of the magnetic flux collecting projections 60 and 60 passes through the magnetic sensor 7 with which the magnetic materials 9 and 9 are in contact, without leaking around. It becomes. As a result, since the magnetic flux passing through the detector 7a increases, the rotational torque can be detected with high accuracy by obtaining the relative angular displacement from the magnetic flux density detected by the magnetic sensor 7.

  As the magnetic material 9, for example, grease or a curable resin mixed with soft magnetic powder such as ferrite powder can be used. As shown in FIG. 4A, the magnetic materials 9 and 9 are applied to both surfaces sandwiching the detection portion 7a of the magnetic sensor 7, and then are attached to the mounting holes 80 as indicated by white arrows. By inserting 70 and positioning the magnetic sensor 7 between the opposing portions of the magnetic flux collecting projections 60, 60, the magnetic flux collecting projections 60, 60 can be easily interposed between the magnetic sensor 7. Thus, the assembly of the magnetic sensor 7 between the opposing portions of the magnetic flux collecting protrusions 60, 60 can be performed by attaching the holder 70 to the housing 8 after applying the magnetic materials 9, 9 to the magnetic sensor 7. The magnetic sensor 7 can be easily assembled.

  When a curable resin is used as the magnetic material 9, the curable resin is cured by heating or ultraviolet irradiation after the holder 70 is attached to the housing 8. As a result, the holding state of the magnetic materials 9 and 9 between the magnetic flux collecting projections 60 and 60 of the magnetic flux collecting rings 6 and 6 and the magnetic sensors 7 and 7 even in a use environment where the temperature is high or vibration is applied. Thus, the rotational torque can be stably detected with high accuracy.

  FIG. 5 is an enlarged view of the vicinity of the magnetic flux collecting projections 60, 60 in another embodiment. In this embodiment, a magnetic rubber (for example, a magnetic powder or a rubber containing iron powder whose surface is treated with an insulating film) is used as the magnetic members 90 and 90. As shown in the drawing, the magnetic members 90 and 90 are mounted so as to cover the tip portions of the magnetic flux collecting projections 60 and 60, and the opposing surfaces are tapered surfaces that are inclined so as to approach each other from the outside to the inside. is there. The magnetic sensor 7 is inserted between the magnetic materials 90 and 90 using the tapered surface as a guide, and the magnetic materials 90 and 90 are elastically held by the projecting portions 90a and 90a that are closest to each other, whereby the magnetic flux collecting projections 60 and Between 60.

  In the present embodiment, as shown in FIG. 5, by aligning the positions of the detection part 7a of the magnetic sensor 7 and the protrusions 90a, 90a of the magnetic materials 90, 90, the tips of the magnetic flux collecting protrusions 60, 60 are aligned. Since the magnetic flux focused on the projecting portions 90a and 90a of the magnetic material 90 and 90 having magnetic properties is concentrated on the detection portion 7a, the magnetic flux passing through the detection portion 7a is further increased, and the rotational torque is further accurately increased. Can be sought. In addition, since elastic rubber is used as the magnetic materials 90, 90, the magnetic sensors 90, 90 are inserted between the magnetic materials 90, 90 so that the magnetic materials 90, 90 can be easily assembled. This can be realized, and the magnetic sensors 7, 7 can be easily removed.

It is a longitudinal cross-sectional view which shows schematically the assembly state of the torque detection apparatus which concerns on this invention. It is a disassembled perspective view of the principal part of the torque detection apparatus which concerns on this invention. It is explanatory drawing which shows the positional relationship of a yoke ring and the magnetic pole of a cylindrical magnet. It is an enlarged view of the magnetism collection protrusion vicinity. It is an enlarged view of the magnetism collection protrusion vicinity in other embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 1st axis | shaft, 2nd axis | shaft 4, Cylindrical magnet, 5a, 5b York ring, 6 Magnetic flux collection ring, 60 Magnetic flux collection protrusion (opposing part), 7 Magnetic sensor (magnetic detection means), 9 Magnetic material (grease, hardening) 90) magnetic material (rubber)

Claims (3)

A cylindrical magnet and two yoke rings are fixed to the first and second shafts that are coaxially connected to each other, and according to the relative angular displacement caused by the action of rotational torque applied to the first and second shafts. A torque configured to obtain the rotational torque by detecting a change in magnetic flux generated in each of the yoke rings by a magnetic detection means disposed between opposing portions of the magnetism collecting rings surrounding each of the yoke rings. The torque detecting device according to claim 1, wherein grease mixed with magnetic powder is interposed between the facing portion of the magnetism collecting ring and the magnetic detecting means . A cylindrical magnet and two yoke rings are fixed to the first and second shafts that are coaxially connected to each other, and according to the relative angular displacement caused by the action of rotational torque applied to the first and second shafts. A torque configured to obtain the rotational torque by detecting a change in magnetic flux generated in each of the yoke rings by a magnetic detection means disposed between opposing portions of the magnetism collecting rings surrounding each of the yoke rings. In the detecting device, a curable resin mixed with magnetic powder is interposed between a facing portion of the magnetism collecting ring and the magnetic detecting means . A cylindrical magnet and two yoke rings are fixed to the first and second shafts that are coaxially connected to each other, and according to the relative angular displacement caused by the action of rotational torque applied to the first and second shafts. A torque configured to obtain the rotational torque by detecting a change in magnetic flux generated in each of the yoke rings by a magnetic detection means disposed between opposing portions of the magnetism collecting rings surrounding each of the yoke rings. in the detection device, rubber mixed with magnetic powder respectively mounted on opposing portions of the magnetic flux collecting rings, the rubber has an inclined tapered surface, as opposed to the surface are close to each other, the bullet to the magnetic detection means A torque detection device characterized by being in contact with each other.

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