JP2009092463A - Torque detection device, electric power steering device, and method of manufacturing torque detection device - Google Patents

Abstract

A magnetic sensor is prevented from being damaged when a torque detector is manufactured.
The torque detector includes first and second units (31, 32) fixed to a sensor housing (30). The first unit 31 includes first and second magnetism collecting rings 36 and 37 and a synthetic resin member 38. The first unit 31 has the first and second magnetism collecting rings 36 and 37 positioned in the holding recess 52 of the sensor housing 30 and the first and second magnetism collecting rings 36 and 37 are synthetic resin members. 38 is resin-molded and fixed to the sensor housing 30. The second unit 32 holds the first and second magnetic sensors 41 and 42 that detect the magnetic flux density between the first and second magnetism collecting rings 36 and 37, and is attached to the sensor housing 30.
[Selection] Figure 2

Description

  The present invention relates to a torque detection device, an electric power steering device, and a method for manufacturing the torque detection device.

The electric power steering device has a torque detection device. This torque detection device has, for example, a magnetic sensor for detecting a magnetic flux that changes according to torque (see, for example, Patent Document 1). This magnetic sensor is fixed to the sensor housing.
JP 2003-149062 A

By the way, a magnetic sensor may be damaged at the time of manufacture of a torque detector. As a result, the manufacturing cost of the torque detection device has increased.
Accordingly, an object of the present invention is to provide a torque detection device, an electric power steering device, and a method for manufacturing the torque detection device that can suppress the occurrence of breakage of a magnetic sensor during the manufacture of the torque detection device.

The magnetic sensor may be attached to the sensor housing in the early stage of the assembly process of the torque detection device. In this case, after the magnetic sensor is attached, other components of the torque detection device are attached to the sensor housing. At this time, the magnetic sensor may be damaged by receiving an impact force.
In the torque detector (20) of the present invention, a pair of magnetism collecting rings (36, 37) magnetically coupled to the corresponding soft magnetic bodies (27, 28) are resin-molded by a synthetic resin member (38). The magnetic flux density between the pair of magnetic flux collecting rings and the first unit (31, 65) held in a state where the pair of magnetic flux collecting rings is positioned in the holding recess (52) of the sensor housing (30). And a second unit (32) attached to the sensor housing. The magnetic sensor (41, 42) is used for detecting the magnetic field.

  According to the present invention, the magnetic sensor and the pair of magnetism collecting rings are provided in different first and second units, respectively. Thereby, the assembly of the magnetic sensor to the sensor housing can be performed at a later timing than the assembly of the pair of magnetism collecting rings to the sensor housing, for example, at the end of the assembly process of the torque detection device. Therefore, the occurrence of breakage of the magnetic sensor due to the assembly of other parts other than the magnetic sensor in the torque detector is prevented. As a result, an increase in manufacturing cost is suppressed. Moreover, since the magnetism collecting ring is resin-molded and positioned in the holding recess, the torque detection accuracy can be improved.

  In the present invention, the synthetic resin member of the first unit (31) may be formed by resin molding using the holding recess of the sensor housing as a part (52) of the molding die (60). In this case, the pair of magnetism collecting rings are positioned on the sensor housing as a part of the mold. Thereby, the two positioning operations required when the pair of magnetism collecting rings are resin-molded separately from the sensor housing are collectively achieved. As a result, the manufacturing cost can be reduced. In addition, since the synthetic resin member of the first unit is molded into the sensor housing, the molding of the synthetic resin member and the fixing of the first unit to the sensor housing can be achieved in a lump. Can be reduced. As a result, the manufacturing cost can be further reduced.

In the present invention, the first unit (65) may include an annular body inserted into the holding recess of the sensor housing. In this case, since the annular body is resin-molded separately from the sensor housing, the pair of magnetism collecting rings in the annular body can be easily positioned outside the sensor housing.
The electric power steering device (1) of the present invention includes a torque detection device (20) for detecting a steering torque, and a steering assist electric motor (driven according to the steering torque detected by the torque detection device). 23). According to the present invention, for example, the operation of attaching the magnetic sensor to the sensor housing in the assembly process of the torque detection device can be performed at the final stage of the assembly process of the electric power steering device. Therefore, damage to the magnetic sensor in the assembly process of the electric power steering device is suppressed. As a result, the manufacturing cost of the electric power steering device can be reduced.

The method for manufacturing a torque detection device according to the present invention is the method for manufacturing the torque detection device, wherein the first unit is held by the sensor housing, and then the second unit is attached to the sensor housing. . According to the present invention, it is possible to reliably prevent the magnetic sensor from being damaged.
In addition, although the alphanumeric characters in the parentheses indicate reference signs of corresponding components in the embodiments described later, the scope of the claims is not limited by these reference signs.

A preferred embodiment of the present invention will be described with reference to the accompanying drawings. In the present embodiment, a description will be given based on a case where the torque detection device is applied to an electric power steering device for an automobile. Note that the torque detection device of the present embodiment may be applied to devices other than the electric power steering device.
FIG. 1 is a schematic diagram of a schematic configuration of an electric power steering apparatus to which a torque detection device according to a first embodiment of the present invention is applied. Referring to FIG. 1, an electric power steering system (EPS) 1 includes a steering shaft 3 connected to a steering member 2 such as a steering wheel, and a first universal joint 4 on the steering shaft 3. An intermediate shaft 5 connected to the intermediate shaft 5, a pinion shaft 7 connected to the intermediate shaft 5 via a second universal joint 6, and rack teeth 9 that mesh with pinion teeth 8 provided near the end of the pinion shaft 7. And a rack bar 10 as a turning shaft extending in the left-right direction of the automobile.

  The pinion shaft 7 and the rack bar 10 constitute a steering gear 11 composed of a rack and pinion mechanism. The rack bar 10 is supported in a rack housing 13 fixed to the vehicle body 12 so as to be linearly reciprocable via a plurality of bearings (not shown). A pair of tie rods 14 are coupled to the rack bar 10. Each tie rod 14 is connected to a corresponding steered wheel 16 via a corresponding knuckle arm 15.

When the steering member 2 is operated and the steering shaft 3 is rotated, this rotation is converted by the pinion teeth 8 and the rack teeth 9 into a linear motion of the rack bar 10 along the left-right direction of the automobile. Thereby, the turning of the steered wheels 16 is achieved.
With reference to FIG. 1, the steering shaft 3 is divided into an input shaft 17 connected to the steering member 2 and an output shaft 18 connected to the pinion shaft 7. The input shaft 17 and the output shaft 18 are connected to each other on the same axis via a torsion bar 19. When steering torque is input to the input shaft 17, the torsion bar 19 is elastically torsionally deformed, whereby the input shaft 17 and the output shaft 18 are rotated relative to each other.

  A torque detection device 20 that detects a steering torque based on the relative rotational displacement between the input shaft 17 and the output shaft 18 via the torsion bar 19 is provided. A vehicle speed sensor 21 for detecting the vehicle speed is also provided. An ECU (Electronic Control Unit) 22 is provided as a control device. An electric motor 23 for generating a steering assist force and a speed reducer 24 for reducing the output rotation of the electric motor 23 are provided.

  Detection signals from the torque detection device 20 and the vehicle speed sensor 21 are input to the ECU 22. The ECU 22 controls the steering assisting electric motor 23 based on the torque detection result, the vehicle speed detection result, and the like. The output rotation of the electric motor 23 is decelerated via the speed reducer 24 and transmitted to the pinion shaft 7 and converted into a linear motion of the rack bar 10 to assist steering.

The electric power steering apparatus 1 has a steering column 25 that rotatably supports the steering shaft 3. A torque detection device 20 is disposed on the steering column 25.
FIG. 2 is a cross-sectional view of the torque detection device 20 of FIG. FIG. 3 is an exploded perspective view of the torque detection device 20 of FIG. 1, partially cut away. Referring to FIGS. 2 and 3, torque detection device 20 includes input shaft 17, output shaft 18, and torsion bar 19 described above. The torque detection device 20 has an annular permanent magnet 26 fixed to the input shaft 17 and annular first and second magnetic yokes 27 and 28 as soft magnetic bodies fixed to the output shaft 18. is doing. The first and second magnetic yokes 27 and 28 are integrally molded by a synthetic resin member 29.

The first and second magnetic yokes 27 and 28 are fixed in a non-contact state with each other and surround the permanent magnet 26 in a non-contact manner from the radially outer side of the steering shaft 3. Each of the first and second magnetic yokes 27 and 28 is magnetically coupled to the permanent magnet 26 by being disposed in a magnetic field formed by the permanent magnet 26.
The torque detection device 20 includes a cylindrical sensor housing 30, first and second units 31 and 32 fixed to the sensor housing 30, and a fixing unit for fixing the second unit 32 to the sensor housing 30. It has two fixing screws 33 as members.

The first unit 31 has annular first and second magnetism collecting rings 36 and 37 as soft magnetic materials. The first unit 31 is disposed in the sensor housing 30. The first unit 31 is formed by integrally molding first and second magnetism collecting rings 36 and 37 with a synthetic resin member 38 as an insulator.
2 and 3, the second unit 32 includes first and second magnetic sensors 41 and 42, a circuit board 43, and a wire bundle 44 electrically connected to the circuit board 43. Have. The electric wire bundle 44 has a plurality of electric wires. The second unit 32 is formed by integrally molding the first and second magnetic sensors 41 and 42, the circuit board 43, and a part of the wire bundle 44 with a synthetic resin member 45 as an insulator.

  FIG. 4 is a schematic perspective view of the first and second magnetic yokes 27 and 28, the first and second magnetic flux collecting rings 36 and 37, and the first and second magnetic sensors 41 and 42 of FIG. is there. 2 and 4, each of the first and second magnetic flux collecting rings 36 and 37 has an annular portion 47 and two claw pieces 48 and 49. Each claw piece 48, 49 protrudes from the annular part 47 toward the outer side in the radial direction of the annular part 47.

  The first and second magnetism collecting rings 36 and 37 are magnetically coupled to the corresponding first and second magnetic yokes 27 and 28, respectively. Specifically, the first magnetism collecting ring 36 is arranged concentrically and non-contactingly with the corresponding first magnetic yoke 27, and surrounds the outer periphery of the first magnetic yoke 27 from the radially outer side. It is out. The second magnetism collecting ring 37 is disposed concentrically and in non-contact with the corresponding second magnetic yoke 28, and surrounds the outer periphery of the second magnetic yoke 28 from the radially outer side.

  The first and second magnetism collecting rings 36 and 37 are magnetically coupled to each other. Specifically, the first and second magnetism collecting rings 36 and 37 are not in contact with each other. At the same time, in the first and second magnetism collecting rings 36 and 37, The claw pieces 49 are relatively close to each other as compared with the annular portions 47. As a result, the first and second magnetism collecting rings 36 and 37 cause the magnetic fluxes from the corresponding first and second magnetic yokes 27 and 28 to be disposed between the corresponding claw pieces 48 and 49, respectively. And it guide | induces to the 2nd magnetic sensor 41,42.

  The first and second magnetic sensors 41 and 42 include, for example, a Hall element and an MR element as detection elements, and detect the magnetic flux induced by the first and second magnetic flux collecting rings 36 and 37. A torque is obtained based on the detected magnetic flux. The circuit board 43 is formed by assembling electric components on a wiring board. The circuit board 43 functions as a power source and a signal processing unit for the first and second magnetic sensors 41 and 42.

  Referring to FIGS. 2 and 3, the sensor housing 30 includes a peripheral wall that forms a part of the steering column 25. The peripheral wall is formed in a cylindrical shape from an aluminum alloy as a metal. The sensor housing 30 has an insertion hole 50 that penetrates the peripheral wall, a mounting surface 51 to which the second unit 32 is mounted, and a holding recess 52 that holds the first unit 31. ing. The holding recess 52 is formed on the inner periphery of the peripheral wall described above, and is formed of an annular recess extending in the circumferential direction of the sensor housing 30 and communicates with the insertion hole 50.

In the present embodiment, the first and second units 31 and 32 are configured as different units separated from each other. As a result, the second unit 32 can be attached to the sensor housing 30 at a later point in time than the first unit 31.
In addition, the first and second units 31 and 32 of the present embodiment are mechanically connected to each other via the sensor housing 30 and can be separated from each other as necessary. Specifically, the first unit 31 is fixed to the sensor housing 30 so as not to be separated. On the other hand, the second unit 32 is fixed to the sensor housing 30 by screws so as to be separable.

  Thereby, for example, when at least one of the first and second magnetic sensors 41 and 42 needs to be replaced, only the second unit 32 including the first and second magnetic sensors 41 and 42 needs to be replaced. . At this time, the first unit 31 can be omitted. Accordingly, the first and second magnetic sensors 41 and 42 are compared with the conventional case where the first and second magnetic flux collecting rings and the first and second magnetic sensors constitute an integral unit. It can be exchanged economically and in a short time. This is because, in the above-described conventional integral unit, the steering shaft is inserted into the first and second magnetism collecting rings. Therefore, when exchanging the first and second magnetic sensors, it is necessary to pull out the steering shaft. As a result, it takes time to replace the unit.

  With reference to FIGS. 2 and 3, in the present embodiment, the first and second magnetism collecting rings 36 and 37 of the first unit 31 are held in a state of being positioned in the holding recess 52 of the sensor housing 30. ing. Specifically, the annular portions 47 of the first and second magnetism collecting rings 36 and 37 are positioned concentrically with the steering shaft 3. Further, the claw pieces 48 and 49 of the first and second magnetism collecting rings 36 and 37 are respectively positioned at predetermined positions in the axial direction and the circumferential direction of the steering shaft 3. In this state, the first and second magnetism collecting rings 36 and 37 are embedded in the synthetic resin member 38. That is, the synthetic resin member 38 as a molded article is formed by injection molding (insert molding) with the first and second magnetism collecting rings 36 and 37 as inserts inserted into the mold. The first and second magnetism collecting rings 36 and 37 are embedded therein. As a result, the first and second magnetic flux collecting rings 36 and 37 and the synthetic resin member 38 are integrally fixed to the holding recess 52 of the sensor housing 30.

  With reference to FIGS. 2 and 3, the first unit 31 forms a bottom 53 of the insertion hole 50 of the sensor housing 30. On the bottom 53, one claw pieces 48 of the first and second magnetism collecting rings 36 and 37 are arranged to face each other, and the first and second magnetism collecting rings 36 and 37 are arranged. The other claw pieces 49 are arranged to face each other. A predetermined amount of gap is formed between the one claw pieces 48 corresponding to each other, and a predetermined amount of gap is formed between the other claw pieces 49 corresponding to each other.

  The second unit 32 is fixed to the sensor housing 30 while being positioned with respect to the first unit 31, and covers the insertion hole 50. The second unit 32 has a flat attached surface 54. The first and second magnetic sensors 41 and 42 protrude from the mounted surface 54. The first magnetic sensor 41 is disposed between the one claw pieces 48 corresponding to each other, and the second magnetic sensor 42 is disposed between the other claw pieces 49 corresponding to each other.

2 and 3, the permanent magnet 26 has a cylindrical shape and is fixed to the input shaft 17 so as to rotate concentrically and integrally. On the outer periphery of the permanent magnet 26, a plurality of magnetic poles, for example, 24 poles (12 poles of N and S poles) are magnetized at equal intervals in the circumferential direction of the permanent magnet 26.
2 and 4, each of the first and second magnetic yokes 27 and 28 includes a disk-shaped ring 55 and a plurality of equally rising from the inner peripheral portion of the plate surface of the ring 55. For example, twelve claws 56 are provided. The rings 55 of the first and second magnetic yokes 27 and 28 are opposed to each other at a predetermined interval in the axial direction of the steering shaft 3 and are arranged concentrically with each other. The claws 56 of the first and second magnetic yokes 27 and 28 protrude in a direction approaching each other and are alternately and evenly arranged so as to be shifted from each other in the circumferential direction of the ring 55.

5A to 5C are schematic diagrams for explaining the operation of the torque detection device 20 of FIG. 2, and FIG. 5D illustrates the twist angle and magnetic flux density generated between the input shaft 17 and the output shaft 18. It is a graph which shows a relationship, The point which shows the relationship of the twist angle corresponding to each state of FIG. 5A, FIG. 5B, and FIG. 5C and magnetic flux density was attached | subjected and illustrated with the code | symbol of 5A, 5B, 5C.
Referring to FIGS. 2 and 5D, permanent magnet 26, first and second magnetic yokes 27 and 28, and first and second magnetic flux collecting rings 36 and 37 form a magnetic circuit. The magnetic flux density of this magnetic circuit changes according to the relative rotation of the input shaft 17 and the output shaft 18. The change in magnetic flux density that occurs at this time is shown in FIG. 5D.

  2B, in the neutral state where no torque acts between the input shaft 17 and the output shaft 18, the tips of the claws 56 of the first and second magnetic yokes 27, 28 are permanently The boundary between the north pole and the south pole of the magnet 26 is indicated. At this time, in each claw 56 of the first and second magnetic yokes 27 and 28, the area facing the north pole of the permanent magnet 26 is equal to the area facing the south pole. As a result of equalization of the magnetic flux that exits the pole, no magnetic flux is generated between the first and second magnetic yokes 27 and 28 (see FIG. 5D).

Referring to FIGS. 2 and 5A, when a one-way torque acts between the input shaft 17 and the output shaft 18, the torsion bar 19 is twisted. As a result, the claws 56 of the first and second magnetic yokes 27 and 28 move relative to the permanent magnet 26.
At this time, in each claw 56 of the first magnetic yoke 27, the area facing the north pole of the permanent magnet 26 becomes larger than the area facing the south pole of the permanent magnet 26. The magnetic flux entering from the pole is larger than the magnetic flux exiting to the S pole. In each claw 56 of the second magnetic yoke 28, the area facing the N pole of the permanent magnet 26 is smaller than the area facing the S pole of the permanent magnet 26, and enters from the N pole in the second magnetic yoke 28. The magnetic flux is smaller than the magnetic flux exiting the S pole. Magnetic fluxes generated in the first and second magnetic yokes 27 and 28 are respectively induced by the corresponding first and second magnetic flux collecting rings 36 and 37, and correspond to each other between the corresponding claw pieces 48 and 49. It is detected by the first and second magnetic sensors 41 and 42 (see FIG. 5D).

2C, when the torque in the other direction acts between the input shaft 17 and the output shaft 18, the second magnetism collecting ring is opposite to the case where the torque in the one direction acts. A magnetic flux is generated from 37 to the first magnetism collecting ring 36 (see FIG. 5D).
2D, within the range of the torsion angle of the torsion bar 19 that is actually used, the magnetic flux density is N poles at each claw 56 of each of the first and second magnetic yokes 27 and 28. Is proportional to the difference between the area facing the S pole and the area facing the S pole. This difference is proportional to the torsion angle of the torsion bar 19 and thus proportional to the magnitude of torque acting between the input shaft 17 and the output shaft 18. That is, the torque can be known based on the detected magnetic flux density. Further, the first and second magnetic flux collecting rings 36 and 37 can average the magnetic flux density between the first and second magnetic yokes 27 and 28 with respect to the entire circumference of the annular portion 47.

  With reference to FIGS. 2 and 3, the torque detection device 20 of the present embodiment can be manufactured, for example, by the following manufacturing method. The manufacturing method of the torque detection device 20 includes a first step in which the first unit 31 is held by the sensor housing 30, a permanent magnet 26, a first and a first step in the sensor housing 30 in which the first unit 31 is held. A second step of assembling the two magnetic yokes 27 and 28 and the like, and a third step of attaching the second unit 32 to the sensor housing 30 after the second step.

  In the first step, first, the first and second magnetism collecting rings 36 and 37 are positioned in the holding recess 52 of the sensor housing 30 and temporarily held by a temporary holding jig (not shown). At this time, for example, the respective annular portions 47 of the first and second magnetism collecting rings 36 and 37 are positioned concentrically with a bearing holding hole 57 as a positioning portion of the sensor housing 30. The bearing holding hole 57 concentrically supports the steering shaft 3 via a bearing 58 (see FIG. 1). Therefore, the first and second magnetism collecting rings 36 and 37 can be positioned concentrically with respect to the steering shaft 3 by positioning concentrically with respect to the bearing holding hole 57.

FIG. 6 is a cross-sectional view of the first unit 31 of the torque detector 20 of FIG. 2 and a molding die for molding the first unit 31. Referring to FIG. 6, first and second magnetic flux collecting rings 36 and 37 positioned as described above are resin-molded by synthetic resin member 38 molded using molding die 60.
The mold 60 includes a first mold member 61, a second mold member 62, and the above-described sensor housing 30 as a third mold member. The first mold member 61 has a cylindrical shape. A molding portion 63 provided on the outer periphery of the first mold member 61 forms the inner periphery of the first unit 31. The forming portion 64 of the second mold member 62 forms the bottom 53 of the insertion hole 50 in the first unit 31. The holding recess 52 as a molding part of the sensor housing 30 forms the outer periphery and the side surface of the first unit 31. The first mold member 61 is fitted to the inner periphery of the sensor housing 30, and the second mold member 62 is fitted to the insertion hole 50 of the sensor housing 30. In this state, the holding recess 52 of the sensor housing 30, the molding part 63 of the first mold member 61, and the molding part 64 of the second mold member 62 form a cavity for molding the first unit 31. It is partitioned. This cavity is filled with a synthetic resin in a molten state. Thereby, the first unit 31 is formed, and the first unit 31 is fixed in the sensor housing 30.

1 and 2, in the second step, the sensor housing 30 to which the first unit 31 is fixed is attached to the bearing 58, the steering shaft 3, the permanent magnet 26, and the first and second magnetic yokes 27. , 28 etc. are attached. In addition, the electric motor 23, the speed reducer 24, and the like are assembled to the steering column 25.
Thereafter, the second unit 32 is attached to the sensor housing 30 in the third step. The third process is the last process in the assembly process of the torque detector 20.

  As described above with reference to FIG. 2, in the present embodiment, (1) the first and second magnetic yokes 27 and 28 as corresponding soft magnetic bodies are magnetically coupled to the first and second magnetic yokes 27 and 28, respectively. The second magnetism collecting rings 36 and 37 are resin-molded by the synthetic resin member 38, and the first and second magnetism collecting rings 36 and 37 are held in a state of being positioned in the holding recess 52 of the sensor housing 30. The first unit 31 and (2) the first and second magnetic sensors 41 and 42 for detecting the magnetic flux density between the first and second magnetism collecting rings 36 and 37, and the sensor housing 30. And a second unit 32 attached to the.

  According to the present embodiment, the first and second magnetic sensors 41 and 42 and the first and second magnetic flux collecting rings 36 and 37 are different from each other in the first and second units 31 and 32, respectively. Provided. Thereby, the assembly of the first and second magnetic sensors 41, 42 to the sensor housing 30 is performed at a timing later than the assembly of the first and second magnetic flux collecting rings 36, 37 to the sensor housing 30, for example. This can be done at the end of the assembly process of the torque detector 20. Accordingly, the first and second components resulting from the assembly of other components of the torque detection device 20 (components other than the first and second magnetic sensors 41 and 42. For example, the first and second magnetic yokes 27 and 28). The occurrence of breakage of at least one of the two magnetic sensors 41 and 42 is prevented. As a result, an increase in manufacturing cost is suppressed. Moreover, since the first and second magnetism collecting rings 36 and 37 are resin-molded and positioned in the holding recess 52, the torque detection accuracy is improved.

  With reference to FIG. 6, in the present embodiment, the synthetic resin member 38 of the first unit 31 is formed by resin molding using the holding recess 52 of the sensor housing 30 as a part of the molding die 60 described above. In this case, the first and second magnetism collecting rings 36 and 37 are positioned on the sensor housing 30 as a part of the mold 60. Thereby, the two positioning operations required when the pair of magnetism collecting rings are resin-molded separately from the sensor housing are collectively achieved. That is, the operation of positioning the pair of magnetism collecting rings on the mold and the operation of positioning the pair of magnetism collecting rings on the sensor housing are accomplished in a lump. As a result, the manufacturing cost can be reduced.

In addition, by molding the synthetic resin member 38 of the first unit 31 to the sensor housing 30, molding of the synthetic resin member 38 and fixing of the first unit 31 to the sensor housing 30 can be achieved collectively. . Therefore, it is possible to reduce the time and labor of assembly. As a result, the manufacturing cost can be further reduced.
Referring to FIG. 1, the electric power steering device 1 includes the above-described torque detection device 20 for detecting the steering torque, and a steering assist device that is driven according to the steering torque detected by the torque detection device 20. The electric motor 23 is provided. As a result, for example, the first and second magnetic sensors 41 and 42 can be attached to the sensor housing 30 in the assembly process of the torque detection device 20 at the final stage of the assembly process of the electric power steering device 1. Become. Accordingly, the first and second magnetic sensors 41 and 42 are prevented from being damaged in the assembly process of the electric power steering device 1. As a result, the manufacturing cost of the electric power steering device 1 can be reduced.

The method for manufacturing the torque detection device 20 according to the present embodiment is characterized in that the first unit 31 is held by the sensor housing 30, and then the second unit 32 is attached to the sensor housing 30. Thereby, it can prevent reliably that the 1st and 2nd magnetic sensors 41 and 42 are damaged.
Moreover, the following modifications can be considered about this embodiment. In the following description, differences from the above-described embodiment will be mainly illustrated and described. Although explanation is omitted about other composition, it is the same as that of the above-mentioned embodiment, and attaches the same numerals.

For example, FIG. 7 is a cross-sectional view of the torque detection device 20 according to the second embodiment of the present invention. With reference to FIG. 7, the torque detection device 20 of the second embodiment has a first unit 65. The first unit 65 of the present embodiment is different from the first unit 31 of the first embodiment described above in the following points, and the other configurations are the same.
The first unit 65 includes an annular body that is formed separately from the sensor housing 30. This annular body is inserted into the holding recess 52 of the sensor housing 30, and the annular body is bonded by the adhesive 66 in a state where the first and second magnetic flux collecting rings 36 and 37 are adjusted with respect to the sensor housing 30. It is fixed to the holding recess 52. The annular body is formed by integrally resin-molding first and second magnetic flux collecting rings 36 and 37 with a synthetic resin member 38. The annular body is formed smaller than the holding recess 52 by a predetermined amount in the axial direction and the radial direction of the sensor housing 30 so that the position of the annular body can be adjusted in the holding recess 52.

  In the first step described above, first, the first unit 65 is formed separately from the sensor housing 30. Thereafter, the first unit 65 is inserted into the holding recess 52 through the insertion hole 50 of the sensor housing 30. With the first unit 65 inserted into the holding recess 52, the first and second magnetism collecting rings 36 and 37 are positioned in the holding recess 52 of the sensor housing 30. Thereafter, the first unit 65 is fixed using the adhesive 66.

As described above, in the present embodiment, the first unit 65 includes an annular body inserted into the holding recess 35 of the sensor housing 30. In this case, the annular body is resin-molded separately from the sensor housing 30. The positioning of the first and second magnetism collecting rings 36 and 37 at this time is easily performed outside the sensor housing 30.
In each of the above embodiments, the permanent magnet 26 may be fixed to the output shaft 18 and the first and second magnetic yokes 27 and 28 may be fixed to the input shaft 17. In addition, various changes can be made within the scope of the matters described in the claims.

1 is a schematic diagram of a schematic configuration of an electric power steering device to which a torque detection device according to a first embodiment of the present invention is applied. It is sectional drawing of the torque detection apparatus of FIG. It is a disassembled perspective view of the torque detection apparatus of FIG. 1, and is partially cut away and shown. It is a typical perspective view of the magnetic yoke of FIG. 2, a magnetism collection ring, and a magnetic sensor. 5A to 5C are schematic diagrams for explaining the operation of the torque detection device of FIG. 2, and FIG. 5D shows the relationship between the twist angle generated between the input shaft and the output shaft and the magnetic flux density. It is a graph, and the points indicating the relationship between the twist angle and the magnetic flux density corresponding to the states of FIGS. 5A, 5B, and 5C are shown with reference numerals 5A, 5B, and 5C. It is sectional drawing of the 1st unit of FIG. 2, and the shaping | molding die for shape | molding this. It is sectional drawing of the torque detection apparatus of the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electric power steering apparatus, 20 ... Torque detection apparatus, 23 ... Electric motor, 27 ... 1st magnetic yoke (soft magnetic body), 28 ... 2nd magnetic yoke (soft magnetic body), 30 ... Sensor housing, 31 ... 1st unit, 32 ... 2nd unit, 36 ... 1st magnetism collection ring, 37 ... 2nd magnetism collection ring, 38 ... Synthetic resin member, 52 ... Holding recessed part, 60 ... Mold, 65 ... 1st 1 unit (annular)

Claims (5)

A pair of magnetic flux collecting rings magnetically coupled to the corresponding soft magnetic bodies are resin-molded by a synthetic resin member, and the pair of magnetic flux collecting rings are held in a state of being positioned in the holding recesses of the sensor housing. A first unit;
A torque detection apparatus comprising: a second unit that holds a magnetic sensor for detecting a magnetic flux density between a pair of magnetic flux collecting rings and is attached to a sensor housing.   2. The torque detection device according to claim 1, wherein the synthetic resin member of the first unit is resin-molded using the holding recess of the sensor housing as a part of the molding die.   The torque detection device according to claim 1, wherein the first unit includes an annular body inserted into a holding recess of the sensor housing.   A torque detection device according to any one of claims 1 to 3 for detecting a steering torque, and a steering assisting electric motor driven in accordance with the steering torque detected by the torque detection device. Electric power steering device.   4. The method for manufacturing a torque detection device according to claim 1, wherein the first unit is held by the sensor housing, and then the second unit is attached to the sensor housing. A method for manufacturing a torque detector.

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