JP4073384B2 - Torque detection device - Google Patents

Description

  The present invention is suitably used for an electric power steering device of a vehicle, and the like. The first shaft and the second shaft are coaxially connected by a connecting shaft, the permanent magnet fixed to the first shaft, and the second shaft. A plurality of soft magnetic bodies that are fixed and arranged in a magnetic field of a permanent magnet to form a magnetic circuit, and a detector that detects a magnetic flux generated in the soft magnetic body, and torque is applied to the first axis or the second axis. The present invention relates to a torque detection device that detects torque based on the output of a detector when added.

  Some steering devices for vehicles reduce the burden on the driver by driving an electric motor to assist steering. This includes an input shaft connected to a steering member (steering wheel, steering wheel), an output shaft connected to a steering wheel by a pinion, a rack, and the like, and a connecting shaft that connects the input shaft and the output shaft. The torque detection device detects the steering torque applied to the input shaft based on the angle, and drives and controls the steering assist electric motor linked to the output shaft based on the detected steering torque value.

  Conventionally, for such a torque detection device of a steering device, a magnetic detection type resolver that detects a rotational position using a coil, an optical encoder detection device that detects transmission of light, or the like is used. In Patent Document 1, an input shaft and an output shaft that are coaxially connected by a torsion bar, a ring-shaped permanent magnet fixed to the input shaft, and fixed to the output shaft are arranged in a magnetic field of the permanent magnet. A magnetic yoke made of a plurality of soft magnetic bodies forming a magnetic circuit and a magnetic sensor for detecting a magnetic flux generated in the magnetic yoke, based on the output of the magnetic sensor when torque is applied to the input shaft. A torque sensor for detecting torque has been proposed.

In Patent Document 1, an input shaft and an output shaft connected coaxially by a torsion bar, a ring-shaped permanent magnet fixed to the input shaft, and fixed to the output shaft are arranged in the magnetic field of the permanent magnet. A magnetic yoke made of a plurality of soft magnetic materials that forms a magnetic circuit, a plurality of magnetic flux collecting rings that are magnetically coupled to the magnetic yoke and induce magnetic flux from the magnetic yoke, and a magnetic flux induced by the magnetic flux collecting ring is detected A torque sensor has been proposed that includes a magnetic sensor and detects torque based on the output of the magnetic sensor when torque is applied to the input shaft.
JP 2003-149062 A

  The torque sensor as described above requires high-precision positioning between the magnetic yoke and the magnetic sensor or high-precision positioning between the magnetism collecting ring and the magnetic sensor at the time of manufacture. There is a problem that it takes time and labor and productivity is lowered. The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a torque detection device that can be easily assembled at the time of manufacture and can improve productivity.

The torque detection device according to the present invention includes a first shaft and a second shaft that are coaxially coupled by a coupling shaft, a permanent magnet fixed to the first shaft, a fixed to the second shaft, and the permanent magnet Two magnetic yokes, which are soft magnetic bodies that are arranged in the magnetic field of the magnetic field, and a detector that detects the magnetic flux generated in the magnetic yoke, and torque is applied to the first axis or the second axis. In the torque detection device for detecting the torque based on the output of the detector when applied, the two magnetic yokes are arranged in a plate-shaped ring in one direction perpendicular to the plate surface. A plurality of isosceles triangular claws that extend are two magnetic yokes that are circumferentially arranged at equal intervals, and the respective claws are opposed to each other so as to be displaced at an appropriate interval in the circumferential direction. Molded into a cylindrical shape and integrated It is characterized in.

In this torque detector, the first shaft and the second shaft are connected coaxially by a connecting shaft, and the permanent magnet is fixed to the first shaft. Two magnetic yokes are fixed to the second axis and arranged in the magnetic field of the permanent magnet to form a magnetic circuit. The detector detects the magnetic flux generated in the magnetic yoke , and torques the first axis or the second axis. Is applied, the torque is detected based on the output of the detector. The two magnetic yokes are two magnetic yokes in which a plurality of isosceles triangular claws extending in one direction perpendicular to the plate surface are provided at equal intervals on a plate-shaped ring, and each of the claws has a circumference. It is molded in a cylindrical shape with a synthetic resin and integrated with the detector in a state of being opposed so as to be displaced at an appropriate interval in the direction .

According to the torque detection device of the present invention, the positioning operation between the magnetic yoke and the magnetic sensor is not necessary, and therefore a torque detection device that can be easily assembled and improved in productivity at the time of manufacture can be realized.

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

  A cylindrical (24 pole) permanent magnet 5 having 24 poles (12 poles each of N and S poles) magnetized at equal intervals in the circumferential direction is fixed coaxially on the input shaft 1. A cylindrical yoke 4 surrounding the permanent magnet 5 with an appropriate gap in the radial direction is fixed coaxially to the output shaft 2. As shown in FIG. 2, the yoke 4 includes two magnetic yokes 4a in which twelve isosceles triangular claws 10 extending in one direction perpendicular to the plate surface are provided at equal intervals on a plate-shaped ring. , 4b (soft magnetic material). The two magnetic yokes 4a and 4b are molded into a cylindrical shape with a synthetic resin in a state where the claws 10 face each other so as to be displaced at an appropriate interval in the circumferential direction.

  The magnetic yokes 4a and 4b are arranged in a magnetic field formed by the permanent magnet 5, and one or a plurality of Hall ICs 6 (Hall elements, detectors) for detecting a magnetic flux generated in the gap between them are inserted into the gap. In this state, the magnetic yokes 4a and 4b are molded and integrated with a synthetic resin together with the magnetic yokes 4a and 4b. The Hall IC 6 is fixed to a housing (not shown), and the lead wire 7 of the Hall IC 6 is soldered to a substrate (not shown), supplying power for operating the Hall IC 6 and obtaining an output detected by the Hall IC 6. The magnetic yokes 4 a and 4 b are arranged in a neutral state where no torque is applied, so that the tips of the respective claws 10 point to the boundary between the N pole and the S pole of the permanent magnet 5.

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

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

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

  The change in the magnetic flux density generated in the gap between the magnetic yoke 4a and the magnetic yoke 4b described above is represented by the electric angle −180 to 180 deg. If it is illustrated corresponding to (mechanical angle-15 to 15 deg.), It becomes a sine wave shape as shown in FIG. The range actually used is -90 to 90 deg. From the rigidity of the torsion bar 3. The magnetic flux density corresponding to the applied torque can be detected. That is, the applied torque can be known based on the detected magnetic flux density.

( Disclosure technology )
Figure 4 is an explanatory diagram showing a configuration of a torque detecting apparatus disclosed, (a) an exploded perspective view, the (b) is a longitudinal sectional view, (c) is a cross-sectional view. The torque detector includes two magnetic flux collecting rings 8 and 8 (auxiliary soft magnetic bodies) that are magnetically coupled to the magnetic yokes 4a and 4b, respectively, and that induce magnetic fluxes from the magnetic yokes 4a and 4b, respectively. As shown in FIG. 5, the magnetism collecting rings 8 and 8 are arranged in parallel and have flat plate-like portions closer to each other, and one or a plurality of Hall ICs 6 are inserted into the gaps between the adjacent portions. Has been.

In the state described above, the magnetism collecting rings 8 and 8 and the Hall IC 6 are molded and integrated with a synthetic resin. Alternatively, the magnetic yokes 4a, 4b is also, in the form on purpose similar embodiment, is molded integrally by synthetic resin to form a yoke 41. The other configuration is the same as the configuration of the torque detection device described in the form status of implementation, the description thereof is omitted.

In the torque detector having such a configuration, the magnetic fluxes generated in the magnetic yokes 4a and 4b are respectively induced by the magnetic flux collecting rings 8 and 8, and the induced magnetic fluxes are located in the adjacent portions of the magnetic flux collecting rings 8 and 8. Collected preferentially and detected by the Hall IC 6. The magnetic flux collecting rings 8 and 8 allow the Hall IC 6 to detect the average of the magnetic flux density generated around the entire circumference of the magnetic yokes 4a and 4b. The other operations are the same as those of the torque detecting device described in the form status of implementation, the description thereof is omitted.

FIG. 1 is an explanatory diagram showing a configuration of an embodiment of a torque detection device according to the present invention.
2 is an exploded perspective view showing a magnetic yoke and a Hall IC of the torque detector shown in FIG.
[FIG. 3] It is explanatory drawing which shows operation | movement of embodiment of the torque detection apparatus based on this invention.
Is an explanatory diagram showing the configuration of [4] the disclosed torque detector.
[5] The magnetic yoke of the torque detection device shown in FIG. 4 is an exploded perspective view showing a magnetic flux collector rings and Hall IC.

Explanation of symbols

1 Input shaft (first axis)
2 Output shaft (second shaft)
3 Torsion bar (connection shaft)
4 Yoke 4a, 4b Magnetic yoke (soft magnetic material)
5 (24 poles) permanent magnet 6 Hall IC (Hall element, detector)
7 Lead wire 8 Magnetic flux collecting ring (auxiliary soft magnetic material)
10 nails

Claims (1)

A first shaft and a second shaft connected coaxially by a connecting shaft, a permanent magnet fixed to the first shaft, and a magnetic circuit fixed to the second shaft and disposed in the magnetic field of the permanent magnet And two detectors for detecting magnetic flux generated in the magnetic yoke, and when the torque is applied to the first shaft or the second shaft, the detector In the torque detection device adapted to detect the torque based on the output of
The two magnetic yokes are two magnetic yokes in which a plurality of isosceles triangular claws extending in one direction perpendicular to the plate surface are provided around a plate-like ring at equal intervals. A torque detector characterized by being integrated in a cylindrical shape with a synthetic resin together with the detector in a state of being opposed so as to be displaced at an appropriate interval in the circumferential direction.

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