JP4470591B2 - Rotation angle detector - Google Patents

Description

  The present invention relates to a rotation angle detection device used for automobile steering and the like, and more particularly to a rotation angle detection device capable of detecting the rotation angle of a steering with high accuracy.

  Conventionally, a method as shown in FIG. 7 is known as a method for detecting the rotation angle. In FIG. 7, the gear A22 is fixedly attached to the shaft 23 whose rotation angle is desired to be detected. There is known a magnetic detection system in which a gear B24 and a gear C25, which are respectively meshed with the gear A22, are held by a main body 26, and a rotation angle of the shaft 23 is detected by rotation of a magnet provided in the gear B24 and the gear C25. Yes. Here, the relative positions of the gear A22, the gear B24, and the gear C25 are determined by the arrangement of the two rotary bearings 28 provided on the gear B24, the shaft portion 27 of the gear C25, and the main body 26.

For example, Patent Document 1 is known as prior art document information related to the invention of this application.
Japanese Patent Laid-Open No. 11-500828

  However, in the rotation angle detecting device configured as described above, the meshing state of the gears is caused by the variation between the rotational centers of the gears B24 and C25 that rotate or hold the gears B24 and C25. Therefore, there is a technical problem in which a so-called backlash is generated between the teeth, and it is difficult to accurately transmit the rotation angle of the shaft 23 to the detection unit due to the backlash. In order to realize an accurate rotation angle detection device, high-precision gear components are required, and there is a problem that the price becomes expensive.

  Further, in the rotation angle detection device having this configuration, a hysteresis error corresponding to the angle when the rotation direction is reversed is generated due to the backlash between the input shaft 23 and the gear A22. There was also a risk that it would be difficult to detect.

  SUMMARY OF THE INVENTION The present invention solves the above-described problems, and an object of the present invention is to provide a high-precision and high-resolution rotation angle detector with a simple configuration using a pair of magnetized magnets. .

  In order to achieve the above object, the present invention has the following configuration.

  According to a first aspect of the present invention, there is provided a first gear elastically connected to the input shaft, and a first magnet which is meshed with the first gear and rotated and magnetized in the center in the radial direction. A fixed second gear, a third gear that rotates in mesh with the second gear, and a second magnet that is radially magnetized in the center, and a second gear and a third gear. An arm that rotatably holds the gear and constantly urges the second gear with respect to the first gear, and is rotatably supported by a fulcrum shaft provided on the case; A rotation angle detection device comprising a circuit board on which a first magnetic detection element and a second magnetic detection element are arranged opposite to a magnet and a second magnet, and a cover that fits into a case. The second gear with the first magnet for measuring the angle is applied to the input shaft by the elastic force. Since the first gear that is engaged and rotated integrally is always biased via the arm, the variation in the distance between the shafts of the first gear and the second gear and the bearings of these gears The generation of the gear meshing gap due to rattling is eliminated, and the rotation of the input shaft is transmitted to the rotation of the first magnet without error, so that an angle error corresponding to the tooth gap may occur. Absent. This makes it possible to detect the angle with high accuracy and to improve the performance of the rotation angle detection device.

  According to a second aspect of the present invention, there is provided an attachment comprising an elastic body that is provided with at least one locking piece that is elastically fitted to a recess provided in the input shaft, and is fixed to the first gear. The input shaft and the boss of the first gear are fitted together without any interference, and the rotational force in the circumferential direction is fitted between the locking piece and the recess provided in the input shaft. By reliably transmitting without slipping, it is possible to prevent the occurrence of angular error due to the backlash of the boss part and the occurrence of angular hysteresis due to the rotation direction, and to enable highly accurate angle detection. An effect is obtained.

  The invention according to claim 3 of the present invention is based on simplification and assembly of the device by integrally forming at least one locking piece that is elastically fitted in the recess provided in the input shaft with the first gear. The effect of preventing the occurrence of errors can be obtained.

  The invention according to claim 4 of the present invention is a rotation angle detecting device having an arm formed thinly by resin molding around a bearing portion supporting the second gear or the third gear. Alternatively, when the third gear is supported by the arm bearing portion of the both-side support structure, the upper arm and the lower arm for sandwiching both gears can be integrally formed, and the resin material that forms the arm when the gear is incorporated The shaft part of the gear can be elastically fitted using the elasticity of the device, so that the assembly of the device becomes easy and the number of parts can be reduced, and the entire rotation angle detection device has a simple and inexpensive configuration. The effect of being able to be obtained.

  According to a fifth aspect of the present invention, there is provided a configuration in which a magnetic unit having a magnet fixed to a central portion and a metal ring accommodated in a circumferential portion is fixedly held in the central portion of the second gear or the third gear. By configuring the magnetic unit by arranging a metal ring on the outer periphery of the magnet, it is possible to prevent the influence of external disturbance magnetic field and to configure the magnetic unit separately from the gear Therefore, it is possible to simplify the configuration of the gear and simplify the incorporation of the metal ring, so that the effect of improving the angle detection accuracy and the convenience of work can be obtained.

  The invention according to claim 6 of the present invention is provided with a magnetic unit having a concave portion with metal plating on the outer peripheral side surface. For example, the magnetic unit is formed of a plateable material, and the outer peripheral surface is subjected to metal plating. As a result, an optimum thin metal ring capable of preventing the influence of an external disturbance magnetic field can be easily configured, and an effect of simplifying assembly and improving detection accuracy can be obtained.

  The invention according to claim 7 of the present invention is provided with a magnetic unit having a concave portion with a metal foil affixed to the outer peripheral side surface, and a general-purpose metal foil is provided along the concave portion by providing a concave portion on the outer peripheral side surface of the magnetic unit. By sticking them together, it is possible to easily construct an optimally thick metal ring that can prevent the influence of an external disturbance magnetic field, and it is possible to obtain an effect of simplifying assembly and improving detection accuracy.

  The rotation angle detection apparatus according to the present invention has the above-described configuration, and the apparatus for detecting the rotation angle of the input shaft is configured to be compact, and a highly accurate and reliable apparatus can be supplied at low cost. There is an effect.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
1 is a plan view showing a configuration of a rotation angle detection device according to Embodiment 1 of the present invention, FIG. 2 (a) is an XX sectional view, FIG. 2 (b) is an YY enlarged sectional view, and FIG. 2 (c) shows the ZZ enlarged sectional view.

  In FIG. 1, FIG. 2 (a), FIG. 2 (b), and FIG. 2 (c), the first gear 1 has an attachment 2 formed of a metal plate having elasticity at the end thereof and passing through the center. It is fixed by screws 3a. A plurality of bent portions 2a projecting inward are provided on the inner peripheral surface of the attachment 2, and a locking piece 2b is formed on the bent portion 2a. Further, as shown in FIG. 2B, the second gear 4 that meshes with and rotates with the first gear 1 can freely rotate its rotating shaft portion 4 a with rotating boss portions 5 a and 6 b of the upper arm 5 and the lower arm 6. Is held in. Further, the third gear 7 that meshes with the second gear 4 and rotates, similarly to the second gear 4, holds the rotating shaft portion 7 a rotatably by the rotating boss portions 5 a and 6 b of the upper arm 5 and the lower arm 6. Has been. Further, the upper arm 5 and the lower arm 6 are integrally fixed by screws 3b with the second gear 4 and the third gear 7 interposed therebetween, and at one end thereof, a fulcrum shaft 8b provided in the case 8 is fixed. Rotating holes 6a and 7b to be fitted are provided.

  As shown in FIG. 2C, a projection 6c is provided at the other end of the upper arm 5 and the lower arm 6 to lock the elastic body 9 made of a tension spring. The other end of the elastic body 9 is the case. 8 is locked to a spring shaft 10. Further, a first magnet 11a and a second magnet 11b magnetized so as to form a magnetic field in the radial direction are bonded or insert-molded at the centers of the second gear 4 and the third gear 7, respectively. The magnetic detection element 12a, which detects the direction of the magnetic field of the magnets 11a and 11b, is fixed on the printed circuit board 12 at a position facing the first magnet 11a and the second magnet 11b. 12b is arranged. As shown in FIG. 2A, the printed circuit board 12 is fixed and held by a case 8 and a cover 13 that are fixed together by screws 3c.

  The operation of the rotation angle detection device configured as described above will be described below using the same diagram.

  In FIG. 1, the upper and lower arms 5 and 6 that rotate and hold the second gear 4 are constantly urged clockwise around the fulcrum shaft 8b by the tensile force of the elastic body 9 made of a tension spring. The second gear 4 is always meshed and rotated while being pressed against the first gear 1 by this biasing force. Therefore, the distance between the shafts of the first gear 1 and the second gear 4 varies, or it depends on the dimensional variations of the rotating boss portions 5a, 6b of the upper and lower arms 5, 6 and the rotating shaft portion 4a of the second gear 4. Even if there is a crack, no gap is generated in the meshing portion of the teeth of the first gear 1 and the second gear 4, and the rotation of the first gear 1 is accurately transmitted to the second gear 4. It will be.

  As shown in FIGS. 1 and 2A, the attachment 2 is provided with a plurality of bent portions 2 a having elastic force toward the inner peripheral direction of the first gear 1 on the end face of the first gear 1. Is fixed. The bent portion 2a of the attachment 2 is provided with a locking piece 2b at a position where the bent portion 2a of the attachment 2 is fitted into the concave portion 14a of the hole formed in the input shaft 14. When the rotation angle detection device of the present invention is attached to the vehicle side, as shown in FIG. 3, the input shaft 14 is inserted while resisting the elastic force of the bent portion 2a of the attachment 2, and the bent portion of the attachment 2 is inserted. The locking piece 2b is attached by elastic fitting in a recess 14a of a hole formed in the input shaft 14. With such an attachment method, the first gear 1 is held in the radial direction by the elastic force of the attachment 2 so that the first gear 1 does not slip on the input shaft 14, and in the rotational direction (circumferential direction), the locking piece 2 b slips. Thus, the rotation of the input shaft 14 is accurately transmitted to the first gear 1.

  Another embodiment of the attachment 2 will be described with reference to FIGS. 4 (a) and 4 (b).

  4A is a plan view showing another example of the attachment 2 according to Embodiment 1 of the present invention, and FIG. 4B is a cross-sectional view thereof.

  The first gear 1 is formed of a resin material having elasticity and wear resistance, such as polyacetal resin. The hole in the central portion of the first gear 1 is provided with a plurality of elastic piece portions 15 provided with convex portions 15a integrally formed at the time of molding inward. Since the action of the elastic piece 15 is the same as that of the attachment 2 described above, the description thereof is omitted. Thus, by forming the attachment 2 integrally with the first gear 1 with resin, it is not necessary to fix the attachment 2 to the first gear 1 with a fastening material such as screws 3a or means such as resin welding. And the number of parts can be reduced. Moreover, since the shape of the locking piece 2b fitted to the concave portion 14a of the input shaft 14 can be freely designed, the fitting state can be optimized.

  As described above, according to the rotation angle detection device according to the configuration of the present invention, transmission of rotation between the input shaft 14 and the first gear 1 and between the first gear 1 and the second gear 4 is transmitted. Therefore, the accuracy of the apparatus can be increased, and the mounting operation itself can be performed only by the insertion operation as described above, so that the incorporation can be simplified.

(Embodiment 2)
In the following description, the same components as those described above are denoted by the same reference numerals as those in FIG. 1 and FIG.

  FIG. 5 is a perspective view showing the configuration of the arm of the rotation angle detection device according to Embodiment 2 of the present invention.

  In FIG. 5, the link 16 is integrally formed by means such as resin molding. A rotation boss portion 5 a that rotatably supports the second gear 4 and the third gear 7 is formed in the center portion, and a space 17 for housing the second gear 4 and the third gear 7 is formed. The vicinity is formed in the thin portion 18. Therefore, when the second gear 4 and the third gear 7 are inserted into the link 16, the thin portion 18 is deformed against the elastic force of the resin, and the second gear 4 and the third gear 7. Therefore, the number of parts can be reduced and the number of assembling steps can be reduced as compared with the case where the arm is formed separately.

(Embodiment 3)
6 (a), 6 (b), and 6 (c) show a magnetic unit of the rotation angle detection device according to the third embodiment of the present invention. In FIG. 6 (a), the magnetic unit 19 is fixed and held by a means such as adhesion or resin welding in a recess provided in the central portion of the second gear 4 or the third gear 7 described above. A magnet 11a fixed by insert molding is attached to the center portion. The magnetic unit 19 is created by means such as resin molding, and a groove portion 19a along the circumference is formed on the outer peripheral portion. By fitting a ring 20 made of, for example, a ferromagnetic material as shown in FIG. 6B into the groove 19a, the first magnet 11a or the second magnet 11b is affected by the magnetic field of disturbance, Further, since unnecessary magnetic fields can be prevented from being radiated to the outside, the distance between the first magnet 11a and the second magnet 11b can be shortened, and the apparatus can be downsized. Have.

  Further, as shown in FIG. 6C, the magnetic unit 19 is formed of a material capable of resin plating such as ABS, PP, etc., and a ferromagnetic material is partially formed in an optimal shape in the groove portion 19a on the outer peripheral side surface. By plating, the same effects as those described above can be realized. In this case, there is no increase in the number of parts as in the case where the ring 20 is created with different parts, and the degree of freedom in the shape of the ring 20 is high.

  As yet another method, a metal foil can be applied to the groove 19a on the outer peripheral side surface of the magnetic unit 19 to achieve a magnetic shield effect. In this case, when a metal ring 20 having a relatively thin wall thickness is required using a general material, an inexpensive and reliable shielding effect can be obtained and the mass productivity of the apparatus is excellent. Is.

  The rotation angle detection device according to the present invention has the effect of simplifying the device and preventing the occurrence of errors due to assembly and supplying a highly accurate and reliable device at a low cost. Suitable for use in etc.

The top view showing the structure of the rotation angle detection apparatus in Embodiment 1 of this invention. (A) XX sectional view of FIG. 1, (b) YY enlarged sectional view of FIG. 1, (c) ZZ enlarged sectional view of FIG. Attachment explanatory drawing to the input shaft of the attachment in Embodiment 1 of this invention (A) Top view which shows the other Example of the attachment in Embodiment 1 of this invention, (b) The same sectional drawing The perspective view of the arm of the rotation angle detection apparatus in Embodiment 2 of this invention (A) Cross-sectional view of a magnetic unit of a rotation angle detector in Embodiment 3 of the present invention, (b) A perspective view of a ring used in the magnetic unit, (c) A cross-sectional view of the magnetic unit Explanatory drawing of the rotation angle detection apparatus of a prior art example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st gear 2 Attachment 2a Bending part 2b Locking piece 3a, 3b, 3c Screw 4 2nd gear 4a Rotating shaft part 5 Upper arm 5a, 6b Rotating boss part 6 Lower arm 6a, 7b Rotating hole 6c Projection 7 First Third gear 7a Rotating shaft 8 Case 8b Support shaft 9 Elastic body 10 Spring shaft 11a First magnet 11b Second magnet 12 Printed circuit board 12a, 12b Magnetic detection element 13 Cover 14 Input shaft 14a Recess 15 Elastic piece 15a Convex Portion 16 Link 17 Space 18 Thin portion 19 Magnetic unit 19a Groove portion 20 Ring

Claims (7)

A first gear elastically connected to the input shaft, a second gear that meshes with the first gear, rotates, and has a first magnet fixed in the radial direction at the center, and the second gear A third gear that meshes with the gear and rotates, and a second magnet magnetized in the radial direction at the center thereof is fixed; and the second gear and the third gear are rotatably held and Including an elastic body for constantly energizing the first gear with respect to the first gear, an arm rotatably supported by a fulcrum shaft provided on the case, the first magnet, and the second magnet A rotation angle detection device comprising: a circuit board on which a first magnetic detection element and a second magnetic detection element are arranged at a position opposed to the first magnetic detection element; and a cover fitted to the case. The rotation angle according to claim 1, further comprising an attachment made of an elastic body that is provided with at least one locking piece that is elastically fitted to a recess provided in the input shaft, and is fixed to the first gear. Detection device. The rotation angle detection device according to claim 1, comprising at least one locking piece that is elastically fitted to a recess provided in the input shaft, and the locking piece is formed integrally with the first gear. The rotation angle detection device according to claim 1, wherein the arm is formed thinly by resin molding around a bearing portion that supports the second gear or the third gear. The rotation angle detection device according to claim 1, wherein a magnetic unit having a magnet fixed to a central portion and a metal ring accommodated in a circumferential portion is fixedly held at the central portion of the second gear or the third gear. The rotation angle detection device according to claim 5, wherein the magnetic unit has a configuration in which a metal plating is applied to an outer peripheral side surface thereof. The rotation angle detection device according to claim 5, wherein the magnetic unit has a configuration in which a metal foil is attached to an outer peripheral side surface thereof.

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