JP4822681B2 - Torque detection device - Google Patents

Description

  The present invention is suitably used for an electric power steering device of a vehicle, and the like. The first shaft and the second shaft are coaxially connected by a connecting shaft, the permanent magnet fixed to the first shaft, and the second shaft. Detects multiple soft magnetic bodies that are fixed and placed in the magnetic field of a permanent magnet to form a magnetic circuit, multiple auxiliary soft magnetic bodies magnetically coupled to the soft magnetic bodies, and magnetic flux induced by the auxiliary soft magnetic bodies The present invention relates to a torque detector that detects a torque based on an output of a detector when torque is applied to a first shaft or a second shaft. .

  As a vehicle steering apparatus, there is an electric power steering apparatus that assists steering by driving an electric motor to reduce a burden on a driver. This includes an input shaft connected to a steering member (steering wheel, steering wheel), an output shaft connected to a steering wheel by a pinion, a rack, and the like, and a connecting shaft that connects the input shaft and the output shaft. The torque detection device detects the steering torque applied to the input shaft based on the angle, and drives and controls the steering assist electric motor linked to the output shaft based on the detected steering torque value. Conventionally, a magnetic detection resolver that detects a rotational position using a coil, an optical encoder detection device that detects transmission of light, or the like is used as a torque detection device of such an electric power steering device.

  Further, in Patent Document 1, as shown in an exploded perspective view (a), a longitudinal sectional view (b) and a transverse sectional view (c) of FIG. The shaft 2, the ring-shaped 24-pole permanent magnet 5 fixed to the input shaft 1, and a plurality of soft magnetic bodies fixed to the output shaft 2 and arranged in the magnetic field of the permanent magnet 5 to form a magnetic circuit 4a and 4b, two magnetic flux collecting rings 8 and 8 which are magnetically coupled to the magnetic yokes 4a and 4b and induce magnetic flux from the magnetic yokes 4a and 4b, and magnetic flux induced by the magnetic collecting rings 8 and 8 Two magnetic sensors 6 and 6 (Hall IC) for detecting the torque are proposed, and when torque is applied to the input shaft 1, a torque sensor for detecting the torque is proposed based on the output of the magnetic sensors 6 and 6. Yes.

Patent Document 2 discloses a magnetic shield for shielding the magnetic flux collecting ring from external magnetic noise while the magnetic yoke is molded with synthetic resin and the magnetic flux collecting ring is molded with synthetic resin. Is disclosed as a torque sensor provided around a molded synthetic resin.
JP 2003-149062 A JP 2004-125717 A

The torque sensor described above has a problem that the ease of assembly of the magnetic shield and its fixing strength are not considered. In addition, the electric power steering device of a vehicle needs a waterproof function and a dustproof function depending on the mounting location. However, when the torque sensor is used in the electric power steering device, the torque sensor naturally has a waterproof function and a dustproof function. There is a problem that it is required.
The present invention has been made in view of the circumstances as described above, and it is an object of the present invention to provide a torque detection device in which a magnetic shield member can be easily assembled and firmly fixed, and has both a waterproof function and a dustproof function. And

  A torque detector according to a first aspect of the present invention includes a permanent magnet and a plurality of soft magnetic bodies that are coaxially fixed and magnetically coupled to a first shaft and a second shaft that are coaxially connected by a connecting shaft, and the soft magnetic body. A plurality of auxiliary soft magnetic bodies magnetically coupled to the detector, a detector for detecting a magnetic flux induced by the auxiliary soft magnetic body, an electronic circuit member connected to the detector, and the auxiliary soft magnetic body, the detector, and the electronic circuit member And a magnetic shield member that surrounds the synthetic resin body, and is housed in a housing having an opening, and a peripheral portion of the opening and a flange provided on the synthetic resin body In the torque detection device that detects the torque applied to the first shaft or the second shaft based on the output of the detector, the magnetic shield member is between the peripheral portion and the flange portion. A sealing portion for sealing the sealing portion , Characterized in that it is fastened between the peripheral edge and the flange portion.

A torque detector according to a second aspect of the present invention includes a permanent magnet and a plurality of soft magnetic bodies that are coaxially fixed and magnetically coupled to a first shaft and a second shaft that are coaxially connected by a connecting shaft, and the soft magnetic body. magnetically coupled with the plurality of auxiliary soft magnetic materials that, an electronic circuit member connected to the detector and the detector for detecting the magnetic flux the auxiliary soft magnetic material is induced, the plurality of soft magnetic material, a plurality of auxiliary to In the torque detection device in which the soft magnetic body and the detector are housed from the opening in a housing having the opening, and the torque applied to the first shaft or the second shaft is detected based on the output of the detector. A portion of the plurality of auxiliary soft magnetic bodies that overlaps the detector, a synthetic resin body in which the detector and the electronic circuit member are molded, and the auxiliary soft magnetic body is protected and the connection of the auxiliary soft magnetic bodies is performed Magnetically shield the shaft in the radial direction and A first magnetic shield member having a flange portion to be attached to a peripheral portion of the portion; and protecting the synthetic resin body, magnetically shielding the radial direction of the detector and the electronic circuit member, and attaching to the peripheral portion And a second magnetic shield member having a flange, wherein each flange of the first magnetic shield member and the second magnetic shield member is fastened together with the peripheral edge.

  According to the torque detection device of the present invention, it is possible to realize a torque detection device in which the magnetic shield member can be easily fixed and firmly fixed, and has both a waterproof function and a dustproof function.

Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments thereof.
(Embodiment 1)
FIG. 1 is an explanatory view showing the configuration of the first embodiment of the torque detection device according to the present invention, where (a) is an exploded perspective view, (b) is a longitudinal sectional view, and (c) is A in (b). It is a cross-sectional view in -A 'plane. In this torque detector, an input shaft 1 (first shaft) and an output shaft 2 (second shaft) are coaxially connected via a small-diameter torsion bar 3 (connecting shaft). The input shaft 1 and the output shaft 2 are connected to the torsion bar 3 by pins 9 respectively.

A cylindrical (24 pole) permanent magnet 5 having 24 poles (12 poles each of N and S poles) magnetized at equal intervals in the circumferential direction is fixed coaxially on the input shaft 1. A cylindrical yoke 4 surrounding the permanent magnet 5 with an appropriate gap in the radial direction is fixed coaxially to the output shaft 2. As shown in FIG. 2, the yoke 4 includes two magnetic yokes 4a in which twelve isosceles triangular claws 10 extending in one direction perpendicular to the plate surface are provided at equal intervals on a plate-shaped ring. , 4b (soft magnetic material). The two magnetic yokes 4a and 4b are molded in a cylindrical shape by the synthetic resin body 17 in a state where the claws 10 face each other so as to be displaced at an appropriate interval in the circumferential direction. However, the surfaces of the magnetic yokes 4 a and 4 b that face the permanent magnet 5 are exposed from the synthetic resin body 17.
Further, the magnetic yokes 4 a and 4 b are arranged in a neutral state where no torque is applied so that the tips of the respective claws 10 point to the boundary between the N pole and the S pole of the permanent magnet 5.

  The torque detection device further includes two magnetic flux collecting rings 8 and 8 (auxiliary soft magnetic bodies) that are magnetically coupled to the magnetic yokes 4a and 4b, respectively, and that induce magnetic fluxes from the magnetic yokes 4a and 4b, respectively. As shown in FIG. 2, the magnetism collecting rings 8, 8 are arranged in parallel and have flat plate-like parts 8 a, 8 a that are closer to each other than the other parts, and one or two in the gaps between the adjacent parts 8 a, 8 a A plurality of Hall ICs 6 (detectors, magnetic sensors) are inserted.

  The magnetism collecting rings 8 and 8 and the Hall IC 6 are molded by the synthetic resin bodies 18a and 18b together with the circuit board 19 (electronic circuit member) on which the electronic circuit connected to the Hall IC 6 is formed. The Hall IC 6 is connected to a circuit board 19 by a plurality of lead wires 7, and the circuit board 19 is connected to an external control device (not shown) by a cord 11.

  However, the mutually opposing surfaces of the magnetic yokes 4a and 4b and the magnetism collecting rings 8 and 8 are exposed from the synthetic resin bodies 17 and 18b. In addition, when molding with synthetic resin, it is molded in two steps, and in the first molding, the electronic components of the Hall ICs 6 and 6 and the circuit board 19 are made of a flexible synthetic resin body 18a (for example, hot melt). In the second molding, the magnetism collecting rings 8 and 8 are molded with a rigid synthetic resin body 18b (for example, PBT). In the synthetic resin body 18b, two flange portions 23, 23 having attachment holes 23a for attachment to a housing such as an electric power steering device to be described later are formed.

A magnetic shield member 26 that shields the magnetism in the radial direction of the input shaft 1 and the output shaft 2 is attached to the synthetic resin body 18a with a machine screw or the like. Further, the synthetic resin body 18b is surrounded by a magnetic shield member 27 that shields the magnetism in the radial direction of the input shaft 1 and the output shaft 2.
As shown in the perspective view of FIG. 3, the magnetic shield member 27 includes a frame-shaped flange portion 27a having two mounting holes 27b and 27b provided so as to overlap the mounting hole 23a of the synthetic resin body 18b. ing.

  As shown in the exploded perspective view of FIG. 4, the housing 15 such as the electric power steering device that houses the torque detection device having such a configuration includes a cylindrical portion 14 that surrounds the output shaft 2 (steering shaft), and the cylindrical portion 14. It has a mounting seat 12 (peripheral portion) projecting at one location on the outer periphery and a through hole 13 (opening) that penetrates the mounting seat 12 in the radial direction. The attachment seat 12 is a surface parallel to the center line of the housing 15 and has a plurality of mounting holes 16 formed therein.

The magnetic shield member 27, the synthetic resin bodies 18 a and 18 b, and the synthetic resin body 17 (not shown) are accommodated in the housing 15 from the through hole 13. The flange portion 27a of the magnetic shield member 27 is sandwiched between the mounting seat 12 of the housing 15 and the portion of the synthetic resin body 18b connected to the flange portions 23, 23 and the flange portions 23, 23, as shown in FIG. As shown in the figure, they are fastened together with screws 29 that pass through the mounting holes 23 a and 27 b and are screwed into the mounting holes 16. Thereby, the collar part 27a (sealing part) of the magnetic shield member 27 seals between the synthetic resin body 18b and the attachment seat 12, and can have a waterproof function and a dustproof function into the housing 15.
The permanent magnet 5 is fitted from an opening at one end (not shown) of the cylindrical portion 14 while being fixed to the input shaft 1 (not shown).

  Below, operation | movement of the torque detection apparatus of such a structure is demonstrated. When no torque is applied to the input shaft 1 or the output shaft 2, the claws 10 of the magnetic yokes 4a and 4b have areas facing the N pole and S pole of the permanent magnet 5, as shown in FIG. Since the magnetic flux entering from the N pole is equal to the magnetic flux exiting from the S pole, no magnetic flux is generated between the magnetic yoke 4a and the magnetic yoke 4b.

  When a one-way torque is applied to the input shaft 1 or the output shaft 2, the torsion bar 3 is twisted, and the relative positions of the claws 10 and the permanent magnets 5 of the magnetic yokes 4a and 4b change. At this time, for example, as shown in FIG. 6A, the area of the magnetic yoke 4a facing the claws 10 is larger in the N pole of the permanent magnet 5 than in the S pole, and the magnetic flux entering from the N pole Becomes larger than the magnetic flux that goes out to the south pole. Further, the area of the magnetic yoke 4b facing the claws 10 is smaller in the N pole of the permanent magnet 5 than in the S pole, and the magnetic flux entering from the N pole is smaller than the magnetic flux exiting to the S pole. As a result, a magnetic flux is generated from the magnetic yoke 4a to the magnetic yoke 4b, and this magnetic flux density increases as the difference in area between the N pole and the S pole facing each claw 10 increases.

  On the other hand, when the torque in the other direction is applied to the input shaft 1 or the output shaft 2, the torsion bar 3 is twisted in the opposite direction to the above, and the claws 10 of the magnetic yokes 4a and 4b and the permanent magnet 5 The relative position changes. At this time, for example, as shown in FIG. 6C, the area of the magnetic yoke 4a facing the claws 10 is smaller in the N pole of the permanent magnet 5 than in the S pole, and the magnetic flux entering from the N pole Becomes smaller than the magnetic flux exiting the S pole. In addition, the area of the magnetic yoke 4b facing each claw 10 is larger in the N pole of the permanent magnet 5 than in the S pole, and the magnetic flux entering from the N pole is larger than the magnetic flux exiting to the S pole. As a result, a magnetic flux is generated from the magnetic yoke 4b to the magnetic yoke 4a, and this magnetic flux density increases as the difference in the area between the N pole and the S pole facing each claw 10 increases.

  The change in the magnetic flux density generated in the gap between the magnetic yoke 4a and the magnetic yoke 4b described above is represented by the electric angle −180 to 180 deg. If it is illustrated corresponding to (mechanical angle-15-15 deg.), It becomes a sine wave shape as shown in FIG. The range actually used is -90 to 90 deg. From the rigidity of the torsion bar 3. Never exceed.

  In accordance with the magnetic flux density of the gap between the magnetic yoke 4a and the magnetic yoke 4b described above, the magnetic flux generated in the magnetic yokes 4a and 4b is induced by the magnetic flux collecting rings 8 and 8, respectively. 8 and 8 are concentrated on the portions adjacent to each other and detected by the Hall ICs 6 and 6. The magnetic flux collecting rings 8 and 8 allow the Hall ICs 6 and 6 to detect the average of the magnetic flux density generated on the entire circumference of the magnetic yokes 4a and 4b.

As described above, the Hall ICs 6 and 6 can detect the magnetic flux density according to the magnetic flux generated in the magnetic flux collecting rings 8 and 8, that is, the magnetic flux density according to the torque applied to the input shaft 1 or the output shaft 2. I can do it. That is, the applied torque can be known based on the detected magnetic flux density. In particular, by reversing the detection direction of the Hall ICs 6 and 6 and obtaining the difference between the outputs, the influences of the swinging, temperature characteristics of the Hall ICs 6 and 6 and the detection sensitivity in the axial direction can be offset and detected. Accuracy can be increased.
In the embodiment described above, the torque is similarly detected even if the Hall ICs 6 and 6 directly detect the magnetic fluxes generated in the magnetic yokes 4a and 4b except for the magnetism collecting rings 8 and 8. It is possible to do.

(Embodiment 2)
FIG. 7 is an explanatory view showing a configuration of a second embodiment of the torque detection device according to the present invention, wherein (a) is an exploded perspective view, (b) is a longitudinal sectional view, and (c) is B of (b). It is a cross-sectional view in -B 'plane. This torque detection device includes a synthetic resin body together with a circuit board 19 (electronic circuit member) on which an electronic circuit in which the plate-like portions 8a and 8a of the magnetism collecting rings 8 and 8 and the Hall IC 6 are connected to the Hall IC 6 is formed. Molded by 18c and 18d.

  When molding with synthetic resin, it is molded in two steps. In the first molding, the flat portions 8a and 8a of the magnetism collecting rings 8 and 8, the Hall ICs 6 and 6 and the electronic components of the circuit board 19 are formed. Molded with a flexible synthetic resin body 18c (for example, hot melt), and the second portion of the flat plate portions 8a and 8a and the synthetic resin body 18c are rigidly combined with a rigid synthetic resin body 18d (for example, PBT). It is molded by. The synthetic resin body 18d is not provided with a flange for mounting on the housing. Further, most of the magnetism collecting rings 8 and 8 are not molded.

  In the synthetic resin bodies 18c and 18d, the magnetism collecting rings 8 and 8, the Hall ICs 6 and 6 and the circuit board 19 are shielded from the radial magnetism of the input shaft 1 and the output shaft 2 to protect the synthetic resin body 18c. A shield member 30 (second magnetic shield member) is attached. The magnetic shield member 30 is made of a hard material such as pressed steel, and includes two flange portions 30a having attachment holes 30b for attachment to the housing. The synthetic resin bodies 18c and 18d are fixed to the magnetic shield member 30 by pouring at the time of molding, press-fitting after formation, or a small screw.

The magnetic flux collecting rings 8 and 8, the Hall ICs 6 and 6 and the circuit board 19 are shielded from the radial magnetism of the input shaft 1 and the output shaft 2 to protect the magnetic flux collecting rings 8 and 8 (first shield). 1 magnetic shield member) surrounds the magnetism collecting rings 8 and 8.
The magnetic shield member 37 is made of a solid material such as pressed steel and includes a frame-like flange portion 37a as shown in the perspective view of FIG. 3, and the flange portion 37a has two attachment holes for attachment to the housing. 37b and 37b are provided.

The housing for housing the torque detection device is the same as the housing 15 shown in FIG. 4, and the flange 30 a of the magnetic shield member 30 and the flange 37 a of the magnetic shield member 37 overlap the mounting seat 12 of the housing 15. It is stored in. In this state, as in the cross-sectional view of FIG. 5 (however, there is no equivalent to the flange portion of the synthetic resin body), the screw 29 that passes through the mounting hole 30b and the mounting hole 37b and is screwed into the mounting hole 16 is used. It is tightened together. Thereby, the collar part 37a (sealing part) of the magnetic shield member 37 can seal between the magnetic shield member 30 and the attachment seat 12, and can have a waterproof function and a dustproof function into the housing 15.
The other configuration and operation of the torque detection device according to the second embodiment are the same as the configuration and operation of the torque detection device according to the first embodiment described above, and a description thereof will be omitted.

  In the torque detection device of the second embodiment, since the magnetic shield member also serves as a protective cover, the structure is simplified, and since most of the magnetism collecting ring is not molded, the amount of synthetic resin used is reduced. In addition, the annealing process for stabilizing the thermal deformation of the synthetic resin and preventing the deformation of the magnetism collecting ring becomes unnecessary. As described above, the component cost and the manufacturing cost can be reduced, and high reliability can be ensured.

It is explanatory drawing which shows the structure of embodiment of the torque detection apparatus which concerns on this invention. It is a disassembled perspective view which shows the magnetic yoke and the magnetism collection ring of the torque detection apparatus which concern on this invention. It is a perspective view which shows the external appearance of a magnetic shielding member. It is a disassembled perspective view which shows a housing. It is sectional drawing which shows the attachment state to the housing of a magnetic shielding member and a synthetic resin body. It is explanatory drawing for demonstrating operation | movement of a torque detection apparatus. It is explanatory drawing which shows the structure of embodiment of the torque detection apparatus which concerns on this invention.

Explanation of symbols

1 Input shaft (first axis)
2 Output shaft (second shaft)
3 Torsion bar (connection shaft)
4a, 4b Magnetic yoke (soft magnetic material)
5 Permanent magnet 6 Hall IC (Hall element, detector)
7 Lead wire 8 Magnetic flux collecting ring (auxiliary soft magnetic material)
10 Claws 11 Code 12 Attachment seat (peripheral part)
13 Through hole (opening)
15 Housing 16 Mounting hole 17, 18a, 18b, 18c, 18d Synthetic resin body 19 Circuit board (electronic circuit member)
23, 30a collar 23a, 27b, 30b, 37b mounting hole 26, 27 magnetic shield member 27a, 37a collar (sealing part)
29 Screw 30 Magnetic shield member (second magnetic shield member)
37 Magnetic shield member (first magnetic shield member)

Claims (2)

Permanent magnets and a plurality of soft magnetic bodies that are coaxially fixed and magnetically coupled to a first axis and a second axis that are coaxially coupled by a coupling shaft, respectively, and a plurality of auxiliary soft magnetic bodies that are magnetically coupled to the soft magnetic body A detector for detecting the magnetic flux induced by the auxiliary soft magnetic body, an electronic circuit member connected to the detector, a synthetic resin body in which the auxiliary soft magnetic body, the detector and the electronic circuit member are molded, A magnetic shield member surrounding the synthetic resin body, housed in a housing having an opening, and a peripheral edge of the opening and a flange provided on the synthetic resin body are fastened together, In the torque detection device for detecting the torque applied to the first axis or the second axis based on the output of the detector,
The magnetic shield member has a sealing portion that seals between the peripheral portion and the flange portion, and the sealing portion is fastened together between the peripheral portion and the flange portion. apparatus. Permanent magnets and a plurality of soft magnetic bodies that are coaxially fixed and magnetically coupled to a first axis and a second axis that are coaxially coupled by a coupling shaft, respectively, and a plurality of auxiliary soft magnetic bodies that are magnetically coupled to the soft magnetic body And a detector for detecting the magnetic flux induced by the auxiliary soft magnetic body and an electronic circuit member connected to the detector, wherein the plurality of soft magnetic bodies, the plurality of auxiliary soft magnetic bodies, and the detector have openings. In a torque detection device that detects torque applied to the first shaft or the second shaft, based on the output of the detector, from the opening in a housing having
A portion of the plurality of auxiliary soft magnetic bodies that overlaps the detector, a synthetic resin body in which the detector and the electronic circuit member are molded, the auxiliary soft magnetic body is protected, and the connecting shaft of the auxiliary soft magnetic body A first magnetic shield member having a flange for attaching to the periphery of the opening, and protecting the synthetic resin body, and magnetizing the detector and the electronic circuit member in the radial direction. And a second magnetic shield member having a flange portion for shielding and attaching to the peripheral edge portion, and the flange portions of the first magnetic shield member and the second magnetic shield member are fastened together with the peripheral edge portion. Torque detection device characterized by the above.

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