JP2004317280A - Torque sensor, its manufacturing method and electric steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a torque sensor capable of improving detection accuracy in the state where a load torque is zero furthermore than hitherto, its manufacturing method and an electric steering device. <P>SOLUTION: In this torque sensor 10 and its manufacturing method, since the relative position between each outside wiring part 53 and each inside wiring part 54 of a pair of resolvers 50, 50 having the same structure agree with each other between both resolvers 50, 50, each dispersion pattern of detection accuracy of the resolvers 50, 50 moving sequentially with rotation of a torsion bar 14 agrees with each other. Therefore, each dispersion of the detection accuracy of the resolvers 50, 50 is compensated by determining the difference between detection angles of both resolvers 50, 50 in the state where the load torque is zero. In this electric steering device 70 equipped with the torque sensor 10, assist torque to steering operation can be controlled accurately by detecting a reaction force to the steering 71 more accurately than hitherto. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a torque sensor capable of detecting a torque by detecting a torsion angle of a torsion bar with a pair of resolvers, a manufacturing method thereof, and an electric steering device.
[0002]
[Related technology]
The resolver is provided, for example, in a servomotor and plays a role in detecting a rotation angle (for example, see Patent Document 1). In recent years, the rotation angle of a torsion bar rotatably provided inside a cylindrical body is detected by a pair of resolvers having different numbers of poles, and the torsion angle of the torsion bar is determined based on the difference between the detected angles. The development of a torque sensor for detecting the applied load torque has been advanced.
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. Hei 10-328952 (Claim 42, [0005])
[0004]
[Problems to be solved by the invention]
By the way, the resolver is provided with an inner winding part rotatably inside the outer winding part, and detects a rotation angle based on a change in mutual inductance between the outer winding part and the inner winding part. However, the detection accuracy of the resolver varies in accordance with the change in the rotation angle of the inner winding with respect to the outer winding. Then, in the torque sensor under development, when calculating the difference between the pair of resolvers, the variation in the accuracy of the detection angles of the resolvers is added to the positive side or the negative side according to the rotation angle of the torsion bar. As shown in (D), even though the load torque was 0, the deviations in the detection angles of both resolvers fluctuated, and the torque could not be detected with high accuracy.
[0005]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a torque sensor, a method of manufacturing the same, and an electric steering device capable of improving detection accuracy in a state where a load torque is zero as compared with the related art.
[0006]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a method of manufacturing a torque sensor, wherein a torsion bar is rotatably provided inside a cylindrical body, and an outer winding portion fixed to the cylindrical body is connected to a torsion bar. A pair of resolvers for detecting the rotation angle of the torsion bar based on the change in mutual inductance with the inner winding portion fixed to the bar is provided, and the load torque applied to the torsion bar is determined from the difference between the detection angles of the pair of resolvers. In the method of manufacturing a torque sensor for detection, the outer winding portions and the inner winding portions of a pair of resolvers are made to have the same structure, and the relative position of the inner winding portion to the outer winding portion is set between the resolvers. The feature is that it is assembled by matching with.
[0007]
According to a second aspect of the present invention, in the method for manufacturing a torque sensor according to the first aspect, a reference position mark for specifying a reference position in a circumferential direction is provided on the outer winding part and / or the inner winding part. The feature is that the outer winding portion and / or the inner winding portion are assembled with the reference position marks being set at predetermined relative positions.
[0008]
According to a third aspect of the invention, in the method of manufacturing a torque sensor according to the second aspect, the reference position marks are arranged on a straight line in the axial direction of the torque sensor, so that the outer winding portions and / or the inner winding portion are arranged. The feature is that the parts are arranged at predetermined relative positions.
[0009]
According to a fourth aspect of the present invention, in the method for manufacturing a torque sensor according to any one of the first to third aspects, the outer winding portions of both resolvers are fitted and fixed inside a common outer fitting sleeve. It is characterized in that the outer fitting sleeve is assembled to the cylindrical body.
[0010]
In the torque sensor according to the present invention, the torsion bar is rotatably provided inside the tubular body, and the mutual inductance between the outer winding portion fixed to the tubular body and the inner winding portion fixed to the torsion bar. A pair of resolvers for detecting the rotation angle of the torsion bar based on the change of the torque, and detecting the load torque applied to the torsion bar from the difference between the detection angles of the pair of resolvers. Identify the outer reference position specifying part for specifying the circumferential reference position of the outer winding part, and specify the circumferential reference position of the inner winding part with the same structure for the winding parts and the inner winding part. An internal reference position specifying unit for performing the operation is provided, and the relative positions of the external reference position specifying unit and the internal reference position specifying unit are matched between the two resolvers.
[0011]
According to a sixth aspect of the present invention, in the torque sensor according to the fifth aspect, both outer reference position specifying portions of both resolvers are arranged on a straight line in the axial direction of the cylindrical body, and both inner reference position specifying portions of both resolvers are provided. It is characterized in that it is arranged on a straight line in the axial direction of the torsion bar.
[0012]
According to a seventh aspect of the present invention, in the torque sensor according to the fifth or sixth aspect, the outer winding portions of both resolvers are fitted and fixed inside a common outer fitting sleeve, and the outer fitting sleeve is attached to the cylindrical body. It has a characteristic when assembled.
[0013]
According to an eighth aspect of the present invention, in the torque sensor according to any one of the fifth to seventh aspects, the outer reference position specifying section is electrically connected to the outer winding section and projects laterally from the outer winding section. The terminal pins provided on the outer winding portions of both resolvers are inserted into pin holes of a common circuit board, and the outer winding portions of both resolvers are positioned at predetermined relative positions. Has features.
[0014]
An electric steering apparatus according to a ninth aspect of the present invention is characterized in that the torque sensor according to any one of the fifth to eighth aspects is provided so as to be connected to a shaft portion that is rotationally driven in accordance with a steering operation.
[0015]
Function and effect of the present invention
According to the manufacturing method of the torque sensor of the present invention, the outer winding portion and the inner winding portion of the pair of resolvers have the same structure, and the relative position of the inner winding portion with respect to the outer winding portion is set to both. Since the resolvers are assembled so as to be matched with each other, when the load torque is 0, the variation patterns of the detection accuracy of the resolvers linked to the rotation of the torsion bar match. As a result, when the difference between the detection angles of both resolvers is obtained in a state where the load torque is 0, the variation in the detection accuracy of the resolvers is canceled out, and the detection accuracy of the torque is improved as compared with the related art.
[0016]
More specifically, a reference position mark for specifying a reference position in the circumferential direction is provided on the outer winding portion and / or the inner winding portion, and the reference position marks are set to a predetermined relative position to form the outer winding portion. Section and / or the inner winding section may be assembled (the invention of claim 2). At this time, if the reference position marks are arranged on a straight line in the axial direction of the torque sensor, it becomes easy to arrange the outer winding portions and / or the inner winding portions at predetermined relative positions. 3 invention).
[0017]
In the torque sensor manufacturing method according to the fourth aspect, the outer winding portions of both resolvers are fitted and fixed inside the common outer fitting sleeve, and then the outer fitting sleeve is assembled to the cylindrical body. The outer winding portions of both resolvers can be easily arranged at predetermined relative positions without being disturbed by other components assembled to the first and second resolvers.
[0018]
According to the torque sensor of the fifth aspect, since the relative positions of the outer winding part and the inner winding part in the pair of resolvers match between the two resolvers, the detection accuracy of the resolver linked to the rotation of the torsion bar is improved. The variation patterns match. As a result, when the difference between the detection angles of both resolvers is obtained in a state where the load torque is 0, the variation in the detection accuracy of the resolvers is canceled out, and the detection accuracy of the torque is improved as compared with the related art.
[0019]
Note that the “inner reference position specifying unit” according to the present invention may be a mark that serves as a mark at the time of assembly, or may be directly or indirectly engaged with a part of the torsion bar in an uneven manner so that the inner winding around the torsion bar may be performed. It may be a concave / convex engaging portion that uniquely determines the assembling position of the wire portion in the circumferential direction. Similarly, the “outer reference position specifying unit” according to the present invention also directly or indirectly engages and recesses with a part of the tubular body to unambiguously assemble the circumferential mounting position of the outer winding part with respect to the tubular body. The concave / convex engaging portion may be determined. Further, a plurality of inner reference position specifying units and a plurality of inner reference position specifying units may be provided.
[0020]
Here, the outer reference position specifying portions of both resolvers are arranged on a straight line in the axial direction of the cylindrical body, and the inner reference position specifying portions of both resolvers are arranged on a straight line in the axial direction of the torsion bar. The relative positions of the reference position specifying unit and the inner reference position specifying unit can be easily matched between both resolvers (the invention of claim 6).
[0021]
In the torque sensor according to the seventh aspect, the outer winding portions of both resolvers can be fitted and fixed in the outer fitting sleeve in a state where the outer fitting sleeve is detached from the cylindrical body, and assembled to the cylindrical body. The outer winding portions of both resolvers can be easily arranged at predetermined relative positions without disturbing other components.
[0022]
In the torque sensor according to claim 8, terminal pins protruding laterally from the outer winding portions of both resolvers are inserted into pin holes of the common circuit board, so that the outer winding portions of both resolvers are in predetermined positions. Since they are positioned at the relative positions, work efficiency is improved.
[0023]
Further, in the electric steering device provided with the above-described torque sensor connected to a shaft portion that is rotationally driven in accordance with the operation of the steering wheel, it is possible to accurately control the assist torque for operating the steering wheel. Invention).
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
<First embodiment>
Hereinafter, a first embodiment according to the present invention will be described with reference to FIGS. FIG. 1 shows the entirety of a torque sensor 10 according to the present embodiment. In the figure, reference numeral 11 denotes a cylindrical body, through which a rotary shaft portion 12 penetrates, and is rotatably supported by bearings 13 provided at both ends of the cylindrical body 11.
[0025]
The rotating shaft 12 includes a torsion bar 14 and first and second extension sleeves 15 and 16. The diameter of the intermediate portion 14C of the torsion bar 14 is smaller than that of both end portions 14A and 14B, and the intermediate portion 14C is torsionally deformed when receiving a load torque.
[0026]
The first extension sleeve 15 covers almost the entire intermediate portion 14C of the torsion bar 14 in a loosely fitted state, and also has one end 14A of the torsion bar 14 (hereinafter, this is referred to as a “base end 14A”, (Referred to as “tip portion 14B”) without any gap. A pin 17 penetrates through a fitting portion between the first extension sleeve 15 and the base end 14A of the torsion bar 14, whereby the first extension sleeve 15 is integrated with the base end 14A of the torsion bar 14. To rotate.
[0027]
A bearing fitting portion 20 in which the bearing 13 is fitted is provided on the outer peripheral surface of the first extension sleeve 15, and a first resolver fitting portion is provided on the distal end portion 14 </ b> B side of the torsion bar 14 from the bearing fitting portion 20. A joint 18 is provided. Further, a first stopper portion 19 having a smaller outer diameter than the first resolver fitting portion 18 is formed on the distal end portion 14B side from the first resolver fitting portion 18, and a minimum diameter portion 21 is further formed on the distal end portion 14B side. Is formed.
[0028]
As shown in FIG. 2, the first stopper portion 19 is formed by forming a pair of flat surfaces 19H, 19H on a peripheral surface of a cylinder in parallel with each other. The two side edges of the flat surface 19H near the remaining arc surface 19C of the cylinder constitute a total of four contact portions 22 that can contact the second extension sleeve 16 described later.
[0029]
As shown in FIG. 1, the second extension sleeve 16 is formed integrally with one end of the pinion gear 23. Then, the first extension sleeve 15 is fitted on the distal end portion 14 </ b> B of the torsion bar 14 and covers the outside of the first stopper portion 19. At the fitting portion between the second extension sleeve 16 and the distal end portion 14B of the torsion bar 14, a concave / convex portion 24 for preventing rotation is formed on the entire circumference. It rotates integrally with the tip portion 14B. Therefore, when the intermediate portion 14C of the torsion bar 14 is twisted, the first extension sleeve 15 that rotates integrally with the base end portion 14A of the torsion bar 14 and the second extension sleeve 16 that rotates integrally with the distal end portion 14B are relatively positioned. Rotate.
[0030]
A bearing fitting portion 25 in which the bearing 13 is fitted is provided on the outer peripheral surface of the second extension sleeve 16. A second resolver is provided on the base end portion 14A side of the torsion bar 14 from the bearing fitting portion 25. A fitting portion 26 is provided. The second resolver fitting portion 26 has the same outer diameter as the first resolver fitting portion 18. The inside of the second resolver fitting part 26 is a second stopper part 27.
[0031]
As shown in FIG. 2, the second stopper portion 27 has a substantially long hole shape symmetrical in the vertical and horizontal directions in FIG. 2 at the same center line (L1, L2 in FIG. 2) as the first stopper portion 19. More specifically, the second stopper portion 27 includes a pair of arc surfaces 27C, 27C having a larger diameter than the arc surface 19C of the first stopper portion 19, which are arranged facing each other in the vertical direction in FIG. A pair of arc surfaces 27D, 27D each having a smaller diameter are provided so as to face each other in the vertical and horizontal directions in the figure, and the four ends of the first stopper portion 19 are provided between the adjacent arc surfaces 27C, 27D. It has a shape connected by four receiving surfaces 28 facing the contact portion 22.
[0032]
When the first extension sleeve 15 rotates by a predetermined angle in any direction with respect to the second extension sleeve 16 by twisting the intermediate portion 14 </ b> C of the torsion bar 14 to one side, the point symmetrical position in the first stopper portion 19. Are in contact with a pair of receiving surfaces 28, 28 of the second stopper 27 to restrict excessive torsional deformation of the torsion bar 14.
[0033]
As shown in FIG. 1, a pair of resolvers 50, 50 are provided between the cylindrical body 11 and the rotating shaft 12, and the resolvers 50, 50 have the same structure. That is, the resolver 50 includes the rotor 50R fixed to the rotary shaft 12 side and the stator 50S fixed to the cylindrical body 11 side. The rotor 50R includes a power receiving coil section 52 and an inner winding section 54, and the stator 50S includes a power feeding coil section 51 and an outer winding section 53. Then, the inner winding 54 is received and excited by electromagnetic induction between the feeding coil 51 and the receiving coil 52, and the inner and outer windings 53, 54 are rotated by the rotation angle of the rotating shaft 12. The electrical angle of the rotating shaft 12 changes based on the change in inductance. Further, the resolver 50 of the present embodiment has, for example, an eight-pole structure, and １ ／ rotation of the inner winding part 54 with respect to the outer winding part 53 corresponds to one cycle of the electrical angle of the resolver 50.
[0034]
FIG. 3 shows an enlarged detail of the resolver 50. As shown in the figure, the power receiving coil section 52 is formed by winding an electric wire 52D around a bobbin 52B. On the other hand, the feeding coil unit 51 has a configuration in which an electric wire 51D is wound around a bobbin 51B, and the outside of the bobbin 51B is covered with another bobbin 51E. A terminal pin 51P protrudes laterally from the bobbin 51E in the power supply coil unit 51, and an electric wire 51D is electrically connected to the terminal pin 51P.
[0035]
The inner winding portion 54 is formed by winding an electric wire 54D around a plurality of teeth provided on the rotor core 54C. Here, the electric wire 54D is wound around the rotor core 54C in a predetermined order and a predetermined number of turns for each tooth, and the winding structure is slightly different for each tooth. Then, in order to specify the circumferential position of the inner winding portion 54, for example, a reference position mark 90 according to the present invention (see FIG. 2) is set at a reference position set on the rotor core 54C. Is also attached).
[0036]
The outer winding portion 53 is formed by winding an electric wire 53D around a plurality of teeth provided on the stator core 53C. Here, the electric wire 53D is wound around the stator core 53C in a predetermined order and a predetermined number of turns for each tooth, and the winding structure is slightly different for each tooth. Then, a plurality of terminal pins 53P (corresponding to the “outer reference position specifying unit” of the present invention, and also serve as “reference position marks”) from the reference position set to specify the circumferential position of the outer winding portion 53. Get) protruding sideways.
[0037]
In FIG. 3, reference numeral 56 denotes a rotating cylinder, on which the power receiving coil portion 52 and the inner winding portion 54 are fitted. The rotating cylinder 56 is fitted to each of the resolver fitting portions 18 and 26 of each of the extension sleeves 15 and 16, and a locking piece 56 </ b> A extending from one end of the rotating cylinder 56 is fitted to each of the resolver fitting portions 18 and 26. It is locked in the formed locking groove 16M and positioned in the axial direction.
[0038]
In FIG. 3, reference numeral 57 denotes an outer fitting sleeve, into which the power supply coil unit 51 and the outer winding unit 53 are fitted. As shown in FIG. 4, a pin insertion window 57 </ b> W is formed in the outer fitting sleeve 57 by cutting off a part of the outer fitting sleeve in the entire axial direction.
[0039]
The structure of each component of the torque sensor 10 is as described above. Next, of the method of manufacturing the torque sensor 10, the steps according to the present invention will be mainly described. First, a pair of inner winding portions 54, 54 produced in the same lot and a pair of outer winding portions 53, 53 produced in the same lot are prepared. Then, the shield disks 83, 83 are fitted from both ends of the outer fitting sleeve 57 (see FIG. 4), and the terminal pin 53P is made to enter from the opening of the pin insertion window 57W at both ends of the outer fitting sleeve 57. Each outer winding portion 53 is fitted to the outer fitting sleeve 57. Next, the shield disks 82 are fitted to the outside of the outer winding portions 53, and the pair of feeding coil portions 51 are fitted to the shield disks 82. Note that an adhesive is applied to the parts that are inserted and assembled into the outer fitting sleeve 57 on the contact surface with the outer fitting sleeve 57.
[0040]
Next, as shown in FIG. 4, a circuit board 58 is arranged so as to cover the pin insertion window 57W of the outer fitting sleeve 57 from the outside (from above in FIG. 4), and a pin hole 59 formed in the circuit board 58 The terminal pin 51P of the feeding coil part 51 and the terminal pin 53P of the outer winding part 53 in each resolver 50 are inserted, respectively. At this time, the phases of the feeding coil unit 51 and the outer winding unit 53 are finely adjusted so that the terminal pins 51P and 53P are smoothly inserted into the pin holes 59. Then, the terminal pins 51P and 53P are fixed to the circuit board 58 by soldering while being inserted into the pin holes 59. Thereby, corresponding ones of the plurality of terminal pins 53P provided on the outer winding portions 53, 53 of the resolvers 50, 50 are aligned in the axial direction of the outer fitting sleeve 57 (direction H in FIG. 4). The outer winding portions 53 are positioned in the same phase. Then, it is fixed at this position by the adhesive, and the stators 50S, 50S of both resolvers 50, 50 are completed as one part.
[0041]
Next, as shown in FIG. 3, the power receiving coil part 52 and the inner winding part 54 are fitted to the outside of the rotary cylinder 56. At this time, shield disks 80 and 81 are fitted on both sides of the inner winding portion 54. It should be noted that an adhesive is applied to the parts to be fitted to the rotating cylinder 56 on the contact surface with the rotating cylinder 56. Here, in the shield disk 81 at one end of the rotary cylinder 56, for example, as shown in FIG. 2, the edge of a position overlapping with the reference position mark 90 attached to the rotor core 54C is cut out to provide a reference position mark according to the present invention. 91 (corresponding to the “inner reference position specifying unit” of the present invention). Then, each component is fixed to the rotary cylinder 56 by the adhesive, and the rotors 50R, 50R of both resolvers 50, 50 are completed separately.
[0042]
Next, the first and second extension sleeves 15 and 16 are assembled to the torsion bar 14, and in this state, the rotor 50 </ b> R of one resolver 50 is attached to the first resolver fitting portion 18 of the first extension sleeve 15. After the fitting and fixing, the rotor 50R of the other resolver 50 is fitted and fixed to the second resolver fitting portion 26 of the second extension sleeve 16. At this time, the load torque is not applied to the torsion bar 14, and the reference position marks 91, 91 (see FIG. 2) provided on both rotors 50R, 50R are positioned so as to be aligned in the axial direction of the torsion bar 14. Perform alignment. As described above, the inner winding portions 54 of the pair of resolvers 50, 50 are assembled in the same phase while the load torque is not applied to the torsion bar 14. The fixing between the rotors 50R, 50R and the extension sleeves 15, 16 may be performed with an adhesive.
[0043]
Next, the stators 50S, 50S, which are made into one part of the two resolvers 50, 50, are inserted and fixed in the main body of the cylindrical body 11, and the rotary shaft 12 is inserted into the cylindrical body 11 together with the rotors 50R, 50R. And are rotatably supported by bearings 13 and 13. As a result, the relative position of the inner winding portion 54 with respect to the outer winding portion 53 is maintained between the two resolvers 50, 50, and the torsion bar 14 can rotate. Thus, the torque sensor 10 is completed.
[0044]
As shown in FIG. 7, for example, the torque sensor 10 of the present embodiment is mounted on an electric steering device 70 provided in an automobile. Specifically, the rotation shaft 12 of the torque sensor 10 is connected to the tip of the steering shaft 78 connected to the handle 71, and the pinion gear 23 of the rotation shaft 12 meshes with the rack 74 in the actuator 72. . The actuator 72 has a built-in electric motor, and converts the rotation output of the electric motor into a linear motion to linearly move the rack 74. Also, tie rods 75, 75 are connected between both ends of the rack 74 and the rotation support portions 76, 76 of the steering wheels 73, 73. Further, the cylindrical body 11 of the torque sensor 10 is fixed to the vehicle body, and the output lines of the resolvers 50, 50 of the torque sensor 10 are connected to the ECU 77. Then, the ECU 77 controls the driving of the actuator 72 based on the load torque of the steering shaft 78 detected by the torque sensor 10. As a result, the rack 74 is driven linearly by the resultant force obtained by adding the output of the actuator 72 to the steering force of the driver to the steering wheel 71 as an auxiliary force, and the steered wheels 73 are steered.
[0045]
Next, the operation of the electric steering device 70 of the present embodiment will be described. When the handle 71 is rotated, a load torque is applied to the torsion bar 14 of the torque sensor 10, and the intermediate portion 14C of the torsion bar 14 is twisted. Then, the first extension sleeve 15 that rotates integrally with the base end portion 14A of the torsion bar 14 and the second extension sleeve 16 that rotates integrally with the distal end portion 14B of the torsion bar 14 relatively rotate, and both resolvers 50, 50 are rotated. There is a difference in electrical angle between the two. The ECU 77 calculates the load torque applied to the rotating shaft 12 based on the difference between the electrical angles of the resolvers 50, 50, and calculates the load torque applied to the rotating shaft 12, that is, the reaction torque applied to the steering wheel 71. The output of the actuator 72 is changed so as to be appropriately changed according to the above.
[0046]
Now, the operation of the torque sensor 10 of the present embodiment will be described in detail as follows. Since the number of poles of the resolver 50 provided in the torque sensor 10 is eight, as shown in FIG. 5A, the resolver 50 rotates at １ ／ rotation of the mechanical angle of the torsion bar 14 (= 360 ° / 8). One cycle of the electrical angle corresponds. Here, FIG. 5B shows the theoretical value and the actual measured value of the electrical angle of the torque sensor 10 superimposed. As shown in the figure, the detection error of the actually measured value with respect to the theoretical value of the electrical angle of the torque sensor 10 changes in conjunction with the rotation angle (mechanical angle) of the torsion bar 14.
[0047]
FIG. 6A shows a detection error of the torque sensor 10 with respect to a rotation angle (mechanical angle) of the torsion bar 14. As shown in the drawing, a variation pattern of the detection error in one cycle of the electrical angle (for example, S1 in FIG. 6A) and one cycle of another electrical angle (for example, in FIG. 6A). This is different from the variation pattern of the detection error in S2). On the other hand, the outer winding portions 53 of the resolvers 50, 50 and the inner winding portions 54, 54 have the same structure and are produced in the same lot. As shown in comparison with FIG. 6 (A) and FIG. 6 (B), it is the same between both resolvers 50,50.
[0048]
Here, assuming that the relative positions of the outer winding part 53 and the inner winding part 54 are displaced between the resolvers 50, 50, the variation pattern of the detection error is also displaced, and the resolvers 50, 50 are displaced. When the difference between the detection angles is obtained, the detection error is added in the positive or negative direction, and as shown in FIG. 6D, even when the load torque is not applied to the torsion bar 14, a load other than 0 is applied. Erroneous detection of torque.
[0049]
However, according to the torque sensor 10 and the method of manufacturing the same according to the present embodiment, the relative positions of the outer winding portion 53 and the inner winding portion 54 are matched between the two resolvers 50, 50. The variation patterns of the detection accuracy of the resolvers 50, 50 linked to the rotation also match. Accordingly, when the difference between the detection angles of the resolvers 50 and 50 is obtained in a state where the load torque is 0, the variation in the detection accuracy of the resolvers is canceled. That is, as shown in FIG. 6C, it is possible to improve the detection accuracy of the torque when the load torque is 0 as compared with the related art (see FIG. 6D). Further, according to the electric steering device 70 including the torque sensor 10, the reaction force to the steering wheel 71 can be detected more accurately than before, and the assist torque for steering operation can be accurately controlled.
[0050]
In the present embodiment, the outer fitting sleeve 57 is detached from the cylindrical body 11, and the outer winding portions 53 of the resolvers 50, 50 are fitted and fixed in the outer fitting sleeve 57. The outer winding portions 53 of both resolvers 50, 50 can be easily arranged at predetermined relative positions without being disturbed by other components assembled to the cylindrical body 11.
[0051]
<Second embodiment>
This embodiment is shown in FIG. 8, in which the first and second extension sleeves 15, 16 are respectively provided with marker grooves 60, 60, and the marker grooves 60 of the first extension sleeve 15 and the second extension sleeves are formed. The 16 mark grooves 60 are arranged in a straight line without applying a load torque to the torsion bar 14. Further, the second extension sleeve 16 of the present embodiment has a structure in which a pin (not shown) is commonly penetrated and fixed to a portion fitted to the torsion bar 14. Except for the above-described portions, the configuration is the same as that of the first embodiment, and thus the same portions are denoted by the same reference numerals and overlapping description will be omitted.
[0052]
When assembling the torque sensor of the present embodiment, the first and second extension sleeves 15 and 16 are detached from the torsion bar 14, and the reference position mark 91 of one of the rotors 50R is marked with a mark groove of the first extension sleeve 15. The rotor 50 </ b> R is fitted and fixed to the first extension sleeve 15 while being positioned at 60. Next, the reference position mark 91 of the other rotor 50R is aligned with the mark groove 60 of the second extension sleeve 16, and the rotor 50R is fitted and fixed to the second extension sleeve 16. Then, the first and second extension sleeves 15 and 16 are assembled to the torsion bar 14 and fixed so that they cannot rotate with pins. Then, the first and second extension sleeves 15, 16 are positioned and fixed to the torsion bar 14, and the reference position marks 91, 91 (see FIG. 2) of both rotors 50R, 50R are aligned with each other in the axial direction of the torsion bar 14. Line up. As a result, the inner winding portions 54 of the pair of resolvers 50, 50 have the same phase in a state where no load torque is applied to the torsion bar 14.
[0053]
According to the present embodiment, the same operation and effect as those of the first embodiment can be obtained, and the reference position mark 91 of the rotor 50R may be aligned for each of the extension sleeves 15 and 16, so that the assembling work is facilitated.
[0054]
The mark grooves 60 also serve as marks for matching the phases of the extension sleeves 15 and 16 with each other. Therefore, the mark grooves 60 can be used for positioning the stoppers 19 and 27 (see FIG. 2) of the first embodiment.
[0055]
<Other embodiments>
The present invention is not limited to the above-described embodiments. For example, the following embodiments are also included in the technical scope of the present invention, and furthermore, various embodiments may be made without departing from the spirit of the present invention. It can be changed and implemented.
(1) In the torque sensor 10 of the embodiment, the number of poles of the pair of resolvers 50 and 50 is eight, but the number of poles of the pair of resolvers is limited to eight as long as they are the same. is not.
[0056]
(2) Although the torque sensor 10 of the above embodiment is used by being incorporated in the electric steering device 70, the torque sensor according to the present invention may be used for something other than the electric steering device.
[0057]
(3) In the first embodiment, the inner winding portions 54, 54 of the resolvers 50, 50 are visually arranged at a fixed relative position. However, the inner winding portions 54, 54 are formed on each component as the "inner reference position specifying unit" of the present invention. By engaging the concave and convex engaging portions, the inner winding portions 54 of the resolvers 50 may be assembled in a fixed relative positional relationship.
[0058]
(4) In the torque sensor 10 of the embodiment, the terminal pins 53P of the outer winding portions 53, 53 of the resolvers 50, 50 are inserted and fixed in the pin holes 59 of the circuit board 58, so that the resolvers 50, 50 are fixed. Although the configuration is such that the outer winding portions 53, 53 of the 50 are assembled in a fixed relative positional relationship, the outer winding portions 53, 53 may be visually aligned.
[Brief description of the drawings]
FIG. 1 is a side sectional view of a torque sensor according to a first embodiment of the present invention. FIG. 2 is a sectional view taken along a line AA in FIG. 1. FIG. 3 is a side sectional view in which a part of the torque sensor is enlarged. FIG. 4 is a perspective view showing a state in which a terminal pin is inserted and fixed to a circuit board. FIG. 5A is a graph showing a relationship between an electrical angle and a mechanical angle. FIG. (A) Graph showing detection error of one resolver (B) Graph showing detection error of the other resolver (C) Deviation between both resolvers when load torque is 0 Graph (D) is a graph showing the deviation between the two resolvers when the load torque is 0 in the conventional torque sensor. FIG. 7 is a conceptual diagram of the electric steering device. FIG. 8 is a mark provided on the extension sleeve of the second embodiment. Perspective view showing grooves [Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Torque sensor 11 ... Cylindrical body 14 ... Torsion bar 50 ... Resolver 53 ... Outer winding part 54 ... Inner winding part 57 ... External fitting sleeve 58 ... Circuit board 59 ... Pinhole 60 ... Marking groove 70 ... Electric steering device 71: Handle 90, 91: Reference position mark

Claims (9)

A torsion bar is rotatably provided inside the cylindrical body, and the torsion bar of the torsion bar is formed based on a change in mutual inductance between an outer winding portion fixed to the cylindrical body and an inner winding portion fixed to the torsion bar. A resolver for detecting a rotation angle is provided in a pair, and a method of manufacturing a torque sensor for detecting a load torque applied to the torsion bar from a difference between detection angles of the pair of resolvers,
The outer winding portions and the inner winding portions of the pair of resolvers have the same structure,
A method of manufacturing a torque sensor, wherein a relative position of the inner winding section with respect to the outer winding section is matched between the two resolvers. The outer winding part and / or the inner winding part is provided with a reference position mark for specifying a reference position in a circumferential direction,
2. The method according to claim 1, wherein the outer winding portion and / or the inner winding portion are assembled by setting the reference position marks to a predetermined relative position. 3. By arranging the reference position marks on a straight line in the axial direction of the torque sensor, the outer winding portions and / or the inner winding portions are arranged at the predetermined relative positions. Item 3. A method for manufacturing a torque sensor according to Item 2. 4. The outer winding sleeve of each of the resolvers is fitted and fixed inside a common outer fitting sleeve, and then the outer fitting sleeve is assembled to the cylindrical body. 3. The method for manufacturing a torque sensor according to claim 1. A torsion bar is rotatably provided inside the cylindrical body, and the torsion bar of the torsion bar is formed based on a change in mutual inductance between an outer winding portion fixed to the cylindrical body and an inner winding portion fixed to the torsion bar. A resolver for detecting a rotation angle is provided as a pair, and a torque sensor for detecting a load torque applied to the torsion bar from a difference between detection angles of the pair of resolvers,
An outer reference position specifying unit for specifying the outer winding unit and the inner winding unit of the pair of resolvers having the same structure, and specifying a circumferential reference position of the outer winding unit; Provide an inner reference position specifying unit for specifying the circumferential reference position of the winding unit,
A torque sensor, wherein a relative position between the outer reference position specifying unit and the inner reference position specifying unit is matched between the two resolvers. The outer reference position specifying portions of both resolvers are arranged on a straight line in the axial direction of the tubular body, and the inner reference position specifying portions of both resolvers are arranged on a straight line in the axial direction of the torsion bar. The torque sensor according to claim 5, wherein: 7. The outer winding portion of each of the resolvers is fitted and fixed inside a common outer fitting sleeve, and the outer fitting sleeve is assembled to the cylindrical body. Torque sensor. The outer reference position specifying unit is configured by a terminal pin that is electrically connected to the outer winding unit and protrudes laterally from the outer winding unit, and is provided on the outer winding unit of both resolvers. The torque according to any one of claims 5 to 7, wherein terminal pins are inserted into pin holes of a common circuit board, and the outer winding portions of both resolvers are positioned at predetermined relative positions. Sensors. An electric steering apparatus comprising the torque sensor according to any one of claims 5 to 8 connected to a shaft portion that is driven to rotate in response to a steering operation.

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