JP2004317281A - Torque sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a torque sensor capable of improving reliability by suppressing an internal stress generated by thermal expansion. <P>SOLUTION: In this torque sensor 10, the first terminal pin 51P having comparatively high stiffness is fixed to a feeding coil part 51, and the second terminal pin 53P having comparatively low stiffness is fixed to an outside wiring part 53, and the first and second terminal pins 51P, 53P are allowed to penetrate a pinhole 59 on a common circuit board 58, to be thereby blocked. Hereby, when each terminal pin 51P, 53P is thermally expanded, the internal stress can be mitigated by deformation of the second terminal pin 53P having the comparatively low stiffness in the state where the first terminal pin 51P having the comparatively high stiffness supports the circuit board 58. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a torque sensor that detects a torque by detecting a torsion angle of a torsion bar with a pair of resolvers.
[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, in the above-mentioned torque sensor, a structure in which a plurality of terminal pins of a feeding coil unit and an outer winding unit provided in a resolver are connected to a common circuit board is preferable. In such a structure, when each part thermally expands, internal stress is generated at a connection portion between the circuit board and each terminal pin and at the terminal pin itself. Therefore, it is necessary to suppress the internal stress and improve reliability. Was required.
[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 capable of suppressing internal stress caused by thermal expansion and improving reliability.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the torque sensor according to the first aspect of the present invention provides a torsion bar rotatably inside a cylindrical body, and an outer winding portion fixed to the cylindrical body and 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, and a torque for detecting a load torque applied to the torsion bar from a difference between the detection angles of the pair of resolvers. In the sensor, the torsion bar is provided with a pair of power receiving coil portions connected to the respective inner winding portions, and the cylindrical body is provided with a pair of power feeding coils for supplying power to the respective power receiving coil portions by electromagnetic induction. Portion is provided, a first terminal pin whose surface of steel is covered with copper, and a second terminal pin made of copper having lower rigidity than the first terminal pin. While fixing to the power coil part, the other terminal pin is fixed to each outer winding part, the first and second terminal pins are fixed to a common circuit board, and the feeding coil part and the outer winding part are fixed. The feature is that it is electrically connected to the circuit board.
[0007]
According to a second aspect of the present invention, in the torque sensor according to the first aspect, a pair of outer winding portions are disposed between the pair of power supply coil portions, and a terminal of the power supply coil portion serves as a first terminal pin. The feature is that the terminal of the outer winding portion is a second terminal pin.
[0008]
According to a third aspect of the present invention, in the torque sensor according to the second aspect, the power supply coil unit is formed by winding an electric wire around a bobbin, and the first terminal pin is fixed to the bobbin.
[0009]
According to a fourth aspect of the present invention, in the torque sensor according to any one of the first to third aspects, the second terminal pin is provided with a portion to be clamped which is flatter than other portions. It is characterized in that it is arranged inside the pinhole of the circuit board.
[0010]
A fifth aspect of the present invention is characterized in that, in the torque sensor according to any one of the first to fourth aspects, a curved portion is provided at an intermediate portion in the axial direction of the second terminal pin.
[0011]
Function and effect of the present invention
<Invention of claim 1>
In the torque sensor according to claim 1, one of the first and second terminal pins having different rigidities is fixed to the feeding coil unit, and the other terminal pin is fixed to the outer winding unit. Since the first and second terminal pins are fixed to the common circuit board, when each terminal pin thermally expands, the relatively high rigidity of the first terminal pin supports the circuit board, and the first and second terminal pins support the circuit board. The internal stress can be reduced by the deformation of the second terminal pin having a low thickness. Thereby, the reliability of the connection between the feeding coil unit and the outer winding unit and the circuit board can be improved.
[0012]
<Inventions of Claims 2 and 3>
In the torque sensor according to the second aspect, since the first terminal pins having relatively high rigidity are arranged on the sides separated from each other to support the circuit board, the support of the circuit board is stabilized. Here, if the first terminal pin is fixed to the bobbin, the first terminal pin itself can be stabilized, thereby stably supporting the circuit board (the invention of claim 3).
[0013]
<Invention of Claim 4>
In the torque sensor according to the fourth aspect, the flat clamped portion of the second terminal pin having relatively low strength is disposed inside the pinhole of the circuit board, so that the clamped portion is reinforced by solder. This prevents stress from being concentrated on the clamped portion. Since the clamped portion has a flat shape, it can be stably gripped by a tool.
[0014]
<Invention of claim 5>
In the torque sensor according to the fifth aspect, since the curved portion is provided at an intermediate portion of the second terminal pin in the axial direction, the internal stress can be reduced by bending deformation of the curved portion.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an 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.
[0016]
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.
[0017]
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.
[0018]
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.
[0019]
As shown in FIG. 1, the second extension sleeve 16 is formed integrally with one end of the pinion gear 23. Then, it is fitted to the distal end portion 14 </ b> B of the torsion bar 14 and covers the outside of the first extension sleeve 15. At the fitting portion between the second extension sleeve 16 and the distal end portion 14B of the torsion bar 14, an uneven portion 24 for preventing rotation is formed on the entire circumference, whereby the second extension sleeve 16 is attached to the torsion bar 14. 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.
[0020]
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.
[0021]
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.
[0022]
In detail, as shown in FIG. 2, the power receiving coil unit 52 is formed by winding an electric wire 52D around a bobbin 52B, and the inner winding unit 54 is formed by winding an electric wire 54D around a plurality of teeth provided on a rotor core 54C. Become. Shield disks 80 and 81 are arranged on both sides of the inner winding portion 54. The power receiving coil portion 52 and the inner winding portion 54 are fitted and fixed to the outer surface of the rotary cylinder 56 to form a rotor 50R. Then, one rotor 50R is fitted and fixed to the first resolver fitting portion 18 of the first extension sleeve 15, and the other rotor 50R is fitted and fixed to the second resolver fitting portion 26 of the second extension sleeve 16. I have. A locking piece 56A extending from one end of the rotary cylinder 56 is locked in a locking groove 16M formed in each of the resolver fitting portions 18, 26, and the rotor 50R is positioned in the axial direction.
[0023]
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. As shown in FIG. 5, a plurality of (see FIG. 3) first terminal pins 51P are fixed to the side surface of the bobbin 51E, and the first terminal pins 51P protrude radially outward of the bobbin 51E. I have. The electric wire 51D of the power supply coil unit 51 is electrically connected to the base end of the first terminal pin 51P.
[0024]
On the other hand, the outer winding portion 53 is formed by winding an electric wire 53D around a plurality of teeth provided on the stator core 53C. A disk 84 is fixed to one side surface of the outer winding portion 53, and a plurality of (see FIG. 3) second terminal pins 53P are fixed to the disk 84. Here, as shown in FIG. 5, the second terminal pin 53P rises in the axial direction of the outer winding portion 53 from the edge of the disk 84, curves in the middle, and has a tip in the radial direction of the outer winding portion 53. It protrudes outward. Further, an electric wire 53D of the outer winding portion 53 is electrically connected to a base end of the second terminal pin 53P. Further, a portion to be clamped 53V that is flatter than the other portions of the second terminal pin 53P is provided on the distal end side of the middle curved portion 53W of the second terminal pin 53P.
[0025]
When assembling and fixing the second terminal pin 53P to the outer winding portion 53, the clamped portion 53V is gripped by a tool (not shown).
[0026]
Now, in the present embodiment, the first terminal pin 51P of the power supply coil unit 51 has higher rigidity than the second terminal pin 53P of the outer winding unit 53. Specifically, as shown in the cross-sectional view of FIG. 4A, the first terminal pin 51P has a structure in which the periphery of steel K1 (for example, mild steel) is covered with copper K2. On the other hand, as shown in FIG. 4B, the second terminal pin 53P is entirely made of copper K2. Thereby, the first terminal pin 51P has higher rigidity than the second terminal pin 53P.
[0027]
The feeding coil part 51 and the outer winding part 53 of both resolvers 50, 50 are fitted and fixed inside the outer fitting sleeve 57. Specifically, as shown in FIG. 3, the outer fitting sleeve 57 has a pin insertion window 57W formed by cutting a part of the outer fitting sleeve in the entire axial direction. Then, the shield disks 83, 83, the disks 84, 84, the outer winding portions 53, 53, the shield disks 82, 82, and the power supply coil portions 51, 51 are fitted in order from both ends of the outer fitting sleeve 57, respectively. Have been. That is, as shown in FIG. 3, a pair of outer winding portions 53, 53 are arranged between a pair of feeding coil portions 51, 51. When the outer winding portion 53 and the power supply coil portion 51 are fitted, the terminal pins 51P and 53P are inserted into the pin insertion windows 57W from the openings of the pin insertion windows 57W at both ends of the outer fitting sleeve 57. Is done.
[0028]
A circuit board 58 is arranged on the side of the outer fitting sleeve 57 so as to cover the pin insertion window 57W. A first terminal pin 51P and a second terminal pin 53P are inserted and soldered into pin holes 59 formed in the circuit board 58, respectively. At this time, the clamped portion 53V of the second terminal pin 53P is disposed inside the pinhole 59 of the circuit board 58 and covered with the solder. As described above, the stators 50S, 50S of both resolvers 50, 50 are a one-piece stator unit. The stator unit is fitted and fixed in the cylindrical body 11.
[0029]
The structure of the torque sensor 10 according to the present embodiment is as described above. The torque sensor 10 is mounted on an electric steering device 70 provided in an automobile, for example, as shown in FIG. 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.
[0030]
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.
[0031]
By the way, a situation may occur in which each part constituting the torque sensor 10 thermally expands due to heat of the vehicle body. However, in the torque sensor 10 of the present embodiment, the first terminal pin 51P having a relatively high rigidity is fixed to the feeding coil portion 51, while the second terminal pin 53P having a relatively low rigidity is fixed to the outer winding portion 53, Since the first and second terminal pins 51P and 53P are fixed through the pin holes 59 of the common circuit board 58, when the terminal pins 51P and 53P thermally expand, the first terminal having relatively high rigidity is used. With the pins 51P supporting the circuit board 58, the internal stress can be reduced by deformation of the second terminal pins 53P having relatively low rigidity. In addition, since the curved portion 53W is provided at an intermediate portion in the axial direction of the second terminal pin 53P, the internal stress can be further reduced by bending deformation by the curved portion 53W. Thereby, the reliability of the connection portion between the power supply coil portion 51 and the outer winding portion 53 and the circuit board 58 can be improved.
[0032]
Further, since the first terminal pins 51P having relatively high rigidity are fixed to both ends of the circuit board 58, the support of the circuit board 58 is stabilized. Furthermore, by placing the flat clamped portion 53V of the second terminal pin 53P having relatively low strength inside the pinhole 59 of the circuit board 58, the clamped portion 53V is reinforced by solder, Concentration of stress on the clamped portion 53V is prevented.
[0033]
<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) 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 in a device other than the electric steering device.
[0034]
(2) In the above-described embodiment, the feeding coil unit 51 is provided with the first terminal pin 51P having relatively high rigidity, and the outer winding unit 53 is provided with the second terminal pin 53P having relatively low rigidity. Conversely, the outer winding portion may be provided with a first terminal pin having relatively high rigidity, and the outer winding portion may be provided with a first terminal pin having relatively low rigidity.
[Brief description of the drawings]
FIG. 1 is a side sectional view of a torque sensor according to an embodiment of the present invention. FIG. 2 is a side sectional view in which a part of the torque sensor is enlarged. FIG. 3 is a perspective view of a state where terminal pins are inserted and fixed to a circuit board. FIG. 4A is a perspective view of a first terminal pin. FIG. 5B is a perspective view of a second terminal pin. FIG. 5 is a perspective view of a state in which the terminal pin is inserted and fixed to a circuit board. FIG. [Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Torque sensor 11 ... Cylindrical body 14 ... Torsion bar 50 ... Resolver 51 ... Power supply coil part 51B, 51E ... Bobbin 51P ... First terminal pin 52 ... Power receiving coil part 53 ... Outer winding part 53P ... Second terminal pin 53V ... Clamped portion 53W Curved portion 54 Inner winding portion 54C Rotor core 58 Circuit board 59 Pinhole

Claims (5)

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,
The torsion bar is provided with a pair of power receiving coil portions connected to the respective inner winding portions,
The cylindrical body is provided with a pair of power supply coil units that supply power to each of the power receiving coil units by electromagnetic induction.
A first terminal pin having a steel surface covered with copper and a second terminal pin made of copper having a lower rigidity than the first terminal pin are fixed to each of the power supply coil units, while the other terminal pin is fixed to the other terminal pin. A terminal pin was fixed to each of the outer winding portions, the first and second terminal pins were fixed to a common circuit board, and the feeding coil portion and the outer winding portion were electrically connected to the circuit board. A torque sensor, characterized in that: The pair of outer winding portions is disposed between the pair of feeding coil portions, and a terminal of the feeding coil portion is the first terminal pin, while a terminal of the outer winding portion is the second terminal. The torque sensor according to claim 1, wherein the torque sensor is a pin. The torque sensor according to claim 2, wherein the power feeding coil unit is formed by winding an electric wire around a bobbin, and the first terminal pin is fixed to the bobbin. The said 2nd terminal pin is provided with the to-be-clamped part which made flat shape from another part, The said to-be-clamped part was arrange | positioned inside the said pinhole of the said circuit board, The said 1st terminal. 4. The torque sensor according to any one of claims 1 to 3. The torque sensor according to any one of claims 1 to 4, wherein a curved portion is provided at an intermediate portion in the axial direction of the second terminal pin.

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