JP2011010537A - Gear device and motor with reducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a gear device and a motor with a reducer, in which a magnetic member is fixed to a gear without a backlash, and which allows the rotating condition of an output shaft to be detected accurately.SOLUTION: A worm reduction gear 10 has a worm wheel 20 for transferring rotation to the output shaft 22, a sensor magnet 36 having a boss magnet 40 magnetized by a magnetization pattern for detecting the rotating condition of the output shaft 22 by a magnetic sensor 38, a projection 54 formed at one end portion in an axial direction in a metal output shaft 22, which is also a rotating shaft of the output shaft 22, and a fixing ring 52 fixed by insert molding to an axial center of the boss magnet 40. The projection 54 is press-fitted into the fixing ring 52. Thus, the sensor magnet 36 is fixed to the worm wheel 20 so as to be rotated coaxially and integrally.

Description

  The present invention relates to a gear device provided with a magnetic member for detecting the rotation state of an output shaft, and a motor with a reduction gear to which the gear device is applied.

  2. Description of the Related Art An electric motor with a speed reduction mechanism, which is unitized by attaching a worm speed reduction mechanism to a motor body, is known in which a magnet, which is a detected member of a rotational position detection sensor, is fixed to the end of the worm wheel in the axial (thickness) direction (For example, refer to Patent Document 1). In this patent document 1, the fixing method by welding is disclosed as a fixing method of the magnet to the worm wheel. In addition, through holes are provided in three connecting portions that connect the inner and outer rings of the sensor magnet member formed in a double ring shape, and three fixing pins that protrude from the worm wheel and pass through the through holes are provided. There is known one in which a sensor magnet member is fixed to a worm wheel by fastening a toothed ring to each of the distal ends (see, for example, Patent Document 2).

JP-A-2005-94821 JP 2008-253121 A

  However, in the method of fixing the worm wheel and the magnet in Patent Document 1, the worm wheel and the magnet (particularly in the case of a bond magnet) may be deformed by the heat of welding. The deformation of the gears and magnets causes erroneous detection (error) of the rotational position sensor. Furthermore, when a large amount of magnetic material is included to increase the magnetic force of the bonded magnet, there is a problem that cracks are likely to occur. On the other hand, in the method for fixing the sensor magnet member and the worm wheel in Patent Document 2, in order to suppress the deterioration of the rotation detection accuracy due to the backlash in the circumferential direction of the sensor magnet member with respect to the worm wheel, the sensor magnet is used. It is necessary to set a small clearance between the through hole of the member and the fixing pin of the worm wheel. Setting the clearance to be small in this way causes an increase in cost due to an improvement in processing accuracy between components and a decrease in assemblability due to a reduction in clearance.

  In view of the above facts, the present invention has an object to obtain a gear device and a motor with a speed reducer that can fix a magnetic member to a gear without rattling and can accurately detect the rotation state of an output shaft. .

  A gear device according to a first aspect of the present invention includes a gear for transmitting rotation to an output shaft and a magnetic material, and directly or indirectly detects the rotation state of the output shaft by a magnetic sensor. A magnetic member having a magnetized portion magnetized with a magnetizing pattern, a metal press-fit portion provided at one end of the rotating shaft of the gear in the axial direction, and a magnetized portion of the magnetic member A metal press-fit member fixed to the shaft center portion by insert molding and fixed to the press-fit portion by press-fitting so that the magnetic member rotates coaxially and integrally with the gear. It is equipped with.

  The gear device according to claim 1, wherein the press-fitting member is fixed to the press-fitting portion from one side in the axial direction of the gear by press-fitting so that the magnetic member rotates coaxially and integrally with the gear. Are fixed to one side (one side surface) in the axial direction. The magnetized portion of the magnetic member formed in a disk shape is magnetized with a predetermined magnetization pattern in advance or after being fixed to a gear. Thereby, the rotation state of an output shaft can be detected directly or indirectly by the change of the magnetic pole or magnetic flux based on the magnetization pattern by relative rotation with respect to the magnetic sensor of the magnetic member accompanying rotation of a gear.

  Here, in this gear device, in order to press-fit and fix a metal press-fit member fixed to the shaft center portion of the magnetic member to a metal press-fit portion provided at one end of the rotation shaft of the gear, The metal members are pressed into each other, and can be firmly fixed to each other while relaxing the stress acting on the magnetic member, and the magnetic member is fixed to the gear so as not to rattle while preventing cracking. Further, since the magnetic member is not heated along with the fixing, deformation and demagnetization of the magnetic member are suppressed, and required rotation detection accuracy can be ensured.

  Thus, in the gear device according to the first aspect, the magnetic member can be fixed to the gear without rattling, and the rotation state of the output shaft can be detected with high accuracy.

  A gear device according to a second aspect of the present invention is the gear device according to the first aspect, wherein the rotation shaft of the gear is cantilevered rotatably at the other end side in the axial direction with respect to the gear, The press-fit portion projects from the gear at one end in the axial direction of the rotating shaft toward the side opposite to the cantilever support side with respect to the gear.

  In the gear device according to claim 2, since the magnetic member is fixed to the side opposite to the cantilever support side of the rotating shaft with respect to the gear, for example, the circuit is formed without making a hole in the control circuit board provided with the magnetic sensor. It becomes possible to arrange | position a board | substrate facing a magnetic member. Therefore, it is easy to secure the circuit board placement space, and the circuit board (outer shape) can be downsized.

  A gear device according to a third aspect of the present invention is the gear device according to the first or second aspect, wherein the magnetic member is coaxially disposed on an outer peripheral portion of a magnetized portion to which the press-fitted member is fixed. And at least one ring-shaped magnetized part magnetized with a magnetized pattern different from the magnetized part to which the press-fitted member is fixed.

  According to a third aspect of the present invention, at least one ring-shaped magnetized portion is disposed on the outer peripheral side of the magnetized portion in which the press-fitting member is fixed to the shaft center portion. The magnetic pattern (magnetization pattern for the corresponding magnetic sensor) is made different in the rotation direction of the gear. For this reason, in this gear apparatus, the signal for detecting many rotation states of an output shaft, or many signals for detecting the rotation state of an output shaft can be obtained. Further, in the present gear device, it can be considered that a magnetized portion is provided in the vicinity of the shaft center by utilizing a portion (boss portion) that holds a press-fit member for fixing the magnetic member to the gear. For this reason, more signals as described above can be obtained while suppressing an increase in the number of ring-shaped magnetized portions.

  A gear device according to a fourth aspect of the present invention is the gear device according to the third aspect, wherein the magnetic member includes a plurality of the magnetized parts spaced apart in the radial direction and is adjacent to the radial direction. The magnetized parts arranged in the same manner are connected so as to rotate coaxially and integrally.

  5. The gear device according to claim 4, wherein the disk-shaped magnetized part and the ring-shaped magnetized part on the outer peripheral side thereof are connected via a connecting part, and two or more ring-shaped magnetized parts are connected. In the configuration having a magnetic part, ring-shaped magnetized parts adjacent in the radial direction are connected to each other via a connecting part. For this reason, a magnetic member can be assembled | attached to a gear, maintaining the relative relationship (relative position) of the mutually different magnetization pattern in each to-be-magnetized part. As a result, errors in the relative positions of the plurality of magnetized patterns are not accumulated as in the configuration in which each magnetized portion is individually assembled to the gear, which contributes to improvement in detection accuracy of the rotation state of the output shaft. .

  A gear device according to a fifth aspect of the present invention is the gear device according to the third or fourth aspect, wherein the magnetic member is at least two magnetization patterns among the magnetization pattern surfaces of the plurality of magnetized portions. The plane is located on the same plane perpendicular to the axis of the rotation axis.

  6. The gear device according to claim 5, wherein at least one of a magnetization pattern surface of a magnetized portion forming an axial center portion (boss portion) of the magnetic member and a magnetization pattern surface of at least one ring-shaped magnetized portion. The two magnetization pattern surfaces are located on the same plane facing one side in the axial direction of the rotating shaft (gear). For this reason, for example, by applying the magnetic sensor to a configuration in which the magnetic sensor is disposed on the same plane facing the at least two magnetization pattern surfaces, the facing interval between the at least two magnetization patterns and the magnetic sensor can be made constant. it can. With this configuration, it is possible to use a magnetic sensor having the same characteristics for the magnetized portion magnetized with the at least two magnetization patterns.

  A gear device according to a sixth aspect of the present invention is the gear device according to any one of the first to fifth aspects, further comprising a positioning structure for positioning the magnetic member in the circumferential direction with respect to the gear. It was.

  According to a sixth aspect of the present invention, the magnetic member is fixed to the gear in a state where the circumferential (rotational) direction position with respect to the gear is determined by the positioning structure. For this reason, the magnetization pattern of the magnetic member can be set at a predetermined circumferential position with respect to the gear. For example, when assembling a magnetic member (magnet) preliminarily magnetized with a predetermined magnetization pattern to a gear previously assembled in the apparatus, the positional relationship in the circumferential direction between the magnetization pattern of the magnetic member and the gear is It can be set uniquely.

  A gear device according to a seventh aspect of the present invention is the gear device according to the sixth aspect, wherein the positioning structure is recessed from the gear side in the magnetized portion so as to be asymmetric with respect to the axis of the gear. Alternatively, it is configured to have a protruding insertion portion and an insertion portion that is protruded or recessed by the same number as the insertion portion from the magnetic member side in the gear and into which the insertion portion is inserted. .

  In the gear device according to claim 7, the magnetic member (magnetization pattern of the magnetized portion) with respect to the gear is inserted by inserting the insertion portion on the magnetized portion (magnetic member) side into the geared portion on the gear side. The position is determined. The insertion portion is asymmetric with respect to the axis of the gear (for example, at least one of the number, arrangement, shape, etc. is asymmetric) and the same number of insertion portions as the insertion portions are provided. By inserting, the positional relationship in the circumferential direction between the magnetization pattern of the magnetic member and the gear can be uniquely set.

  According to an eighth aspect of the present invention, there is provided a motor with a speed reducer, wherein the motor unit and the gear device according to any one of the first to seventh aspects decelerate rotation of the motor unit and transmit it to the output shaft. And a speed reduction portion applied and configured as at least a part of the speed reduction mechanism that is coupled to the output shaft.

  In the motor with a reduction gear of the gear device according to the eighth aspect, when the motor unit is driven, the torque is amplified while being transmitted to the output shaft while the rotation of the motor unit is decelerated by the reduction mechanism. In the present motor with a speed reducer, the speed reduction mechanism is configured by applying the gear device according to any one of claims 1 to 8, so that the rotation state of the output shaft, that is, the driven member (load device) ) Can be detected with high accuracy.

  A motor with a speed reducer according to an invention according to claim 9 is the motor with a speed reducer according to claim 8, wherein the speed reducer is any one of claims 2 to 5, or claims 6 and 6. Of the seventh aspect, the gear device according to any one of the parts dependent on the second aspect is applied and configured as at least a part of a speed reduction mechanism that decelerates the rotation of the motor unit and transmits it to the output shaft. A case housing the speed reduction mechanism including the gear device, and a control circuit for driving and controlling the rotation of the magnetic sensor and the motor unit, on the projecting side of the press-fitting portion with respect to the gear in the case, And a control board arranged to face the magnetic member and to face the magnetic member without penetrating the rotating shaft.

  In the motor with a reduction gear according to claim 9, the magnetic member is fixed to the side opposite to the cantilever support side of the rotation shaft with respect to the gear, and the circuit board and the circuit board are formed on the control circuit board without making a hole. The magnetic sensor is arranged to face the magnetic member. Therefore, it is easy to secure an arrangement space for the circuit board in the case, and the circuit board (outer shape) can be reduced in size.

It is a perspective view which isolate | separates and shows the worm wheel and sensor magnet which comprise the worm reduction mechanism which concerns on the 1st Embodiment of this invention. It is a figure which shows the principal part of the worm reduction mechanism which concerns on the 1st Embodiment of this invention, Comprising: (A) is a sectional side view of the fixed state of a worm wheel and a sensor magnet, (B) is a worm wheel and a sensor magnet. FIG. It is a perspective view which cuts and shows the separation state of the worm wheel and sensor magnet which constitute the worm deceleration mechanism concerning a 1st embodiment of the present invention. It is a perspective view which shows the sensor magnet which comprises the worm reduction mechanism which concerns on the 1st Embodiment of this invention. It is a figure which shows the fixing ring which comprises the worm reduction mechanism which concerns on the 1st Embodiment of this invention, Comprising: (A) is a perspective view which shows a 1st example, (B) is a perspective view which shows a 2nd example, ( C) is a perspective view showing a third example. FIG. 8 is a cross-sectional view taken along line 6-6 in FIG. 7, showing the wiper motor to which the worm reduction mechanism according to the first embodiment of the present invention is applied. It is a side view which shows the external appearance of the wiper motor to which the worm reduction mechanism which concerns on the 1st Embodiment of this invention was applied. It is a perspective view which isolate | separates and shows the worm wheel and sensor magnet which comprise the worm reduction mechanism which concerns on the 2nd Embodiment of this invention. It is a figure which shows the principal part of the worm reduction mechanism which concerns on the 2nd Embodiment of this invention, Comprising: (A) is a sectional side view of the fixed state of a worm wheel and a sensor magnet, (B) is a worm wheel and a sensor magnet. FIG. It is a perspective view which cuts and shows the separation state of the worm wheel and sensor magnet which constitute the worm speed reduction mechanism concerning a 2nd embodiment of the present invention.

  A worm reduction device 10 as a gear device according to a first embodiment of the present invention and a wiper motor 11 as a motor with a reduction mechanism to which the worm reduction device 10 is applied will be described with reference to FIGS. First, the overall configuration of the worm speed reduction device 10 will be described together with the wiper motor 11, and then the sensor magnet 36 as a magnetic member and the sensor magnet 36 for fixing the worm wheel 20 as a gear, which are the main parts of the present embodiment. The magnet fixing structure 50 will be described.

(Overall configuration of wiper motor)
FIG. 7 is a side view showing the appearance of the wiper motor 11 to which the worm reduction device 10 according to the embodiment of the present invention is applied. FIG. 6 is taken along line 6-6 in FIG. A cross-sectional view is shown. As shown in these drawings, the wiper motor 11 includes a motor main body 12, a speed reduction unit 14 to which the worm speed reduction device 10 is applied, and a control unit 15 as main parts. The motor main body 12 has a rotating shaft 16 protruding from the worm reduction device 10 and is configured to rotate the rotating shaft 16 based on the control of the control unit 15. In this embodiment, the motor body 12 is configured to rotate the rotating shaft 16 forward and backward based on the control of the control unit 15.

  The worm speed reduction device 10 includes a worm speed reduction mechanism including a worm 18 provided so as to rotate coaxially and integrally with a rotating shaft 16 and a worm wheel 20 meshed with the worm 18. In this embodiment, an output shaft 22 as an output shaft is fixedly connected to the axial center portion of the worm wheel 20 so as to rotate coaxially and integrally. Therefore, the worm reduction device 10 in this embodiment is a one-stage reduction mechanism. Further, grease as a lubricant is applied to the teeth 18A and 20A that are meshing portions of the worm 18 and the worm wheel 20.

  The worm reduction device 10 is accommodated in the case 24. The case 24 is configured by joining the first case 26 and the second case 28 while abutting each other at the opening end, and has a substantially rectangular shape in plan view as shown in FIG. In this embodiment, the worm speed reducer 10 is disposed in a gear chamber 24A as a mechanism accommodating chamber formed mainly in the first case 26 as shown in FIG. 6, and the output shaft 22 is in the first case. 26, the tip 22 </ b> A protrudes outside the case 24. A cylindrical bearing holding portion 26 </ b> A is formed in a through portion of the output shaft 22 in the first case 26, and the output shaft 22 is rotatably supported around its own axis via a bearing 30. That is, the output shaft 22 is cantilevered by the case 24 via the bearing 30 on one axial side with respect to the worm wheel 20.

  On the other hand, in the control substrate chamber 24B as a substrate storage chamber formed mainly in the second case 28 in the case 24, the control unit 15 (the control substrate 34) is mainly accommodated and fixed. The control unit 15 includes a rotation detection unit 32 for detecting (detecting) the rotation of the output shaft 22 and a control board provided with a control circuit for controlling the rotation of the motor body 12 based on a signal from the rotation detection unit 32. 34 as a main part. The control board 34 is held in the control board chamber 24B so as to face one end side in the axial direction of the worm wheel 20 (the side on which the output shaft 22 does not protrude) (the holding structure is not shown).

  The rotation detection unit 32 includes a sensor magnet 36 provided on the worm wheel 20 that rotates integrally with the output shaft 22, and a magnetic sensor 38 provided on the control board 34. Although details will be described later, the sensor magnet 36 includes a boss magnet (sensor magnet) 40 as shown in FIG. 1 and a plurality of (two in this embodiment) coaxially arranged on the outer peripheral side of the boss magnet 40. The ring magnets 42 and 44 are provided. The boss magnet 40 and the ring magnets 42 and 44 constituting the sensor magnet 36 are each formed with a magnetized pattern by adjoining at least one pair of N pole and S pole in the circumferential direction. In FIG. 1, the boss magnet 40 and the ring magnets 42 and 44 have portions having different polarities depending on the presence or absence of dots.

  The sensor magnet 36 described above is fixedly attached to one end in the axial direction of the worm wheel 20 so as to rotate coaxially and integrally by a magnet fixing structure 50 described later. In this embodiment, a peripheral wall 20 </ b> B that covers the sensor magnet 36 from the radially outer side is erected from the peripheral edge of the worm wheel 20.

  The magnetic sensor 38 includes at least one Hall element that outputs a signal corresponding to a change in magnetic pole or magnetic flux for each of the boss magnet 40 and the ring magnets 42 and 44 constituting the sensor magnet 36. In this embodiment, the magnetic sensor 38 is configured by including a total of four Hall elements, Hall elements 38A and 38D for the boss magnet 40, Hall element 38B for the ring magnet 42, and Hall element 38C for the ring magnet 44. ing. As shown in FIG. 6, the Hall elements 38 </ b> A to 38 </ b> D are arranged so as to face the corresponding boss magnets 40 and ring magnets 42 and 44 in the control board 34 in the axial direction of the worm wheel 20.

  In the rotation detection unit 32 described above, the magnetization patterns of the boss magnet 40 and the ring magnets 42 and 44 with respect to the Hall elements 38A to 38D (installation positions) are different, and the rotation state of the worm wheel 20, that is, the output shaft 22 is determined. It is possible to detect a plurality of rotational positions. In the present embodiment in which the Hall elements 38A to 38D are arranged along the diameter direction of the sensor magnet 36 as shown in FIG. 6, each sensor magnet 36 alone (before assembly) is shown in FIG. The magnetization patterns of the boss magnet 40 and the ring magnets 42 and 44 (the circumferential position of the boundary between the N pole and the S curve) are different. Thereby, in the wiper motor 11, for example, a storage position of a wiper arm (not shown), a lower inversion position, an upper inversion position, and a plurality of other control positions (positions serving as a reference for control) can be set.

  A control circuit formed on the control board 34 controls forward / reverse rotation (operation, inversion) and stop of the motor body 12 based on a signal from the rotation detection unit 32. Since this control circuit can adopt a known configuration as appropriate, its description is omitted.

  Further, as shown in FIG. 6, the wiper motor 11 includes a cover member 46 for preventing grease from scattering from the gear chamber 24 </ b> A to the control board chamber 24 </ b> B in the case 24. The cover member 46 divides the space in the case 24 into a gear chamber 24A and a control board chamber 24B. In the example shown in FIG. 6, the cover member 46 is configured to include the window portion 46 </ b> A that exposes the sensor magnet 36 to the magnetic sensor 38.

(Configuration of sensor magnet)
As shown in FIGS. 1 to 3, the sensor magnet 36 as a magnetic member includes a boss magnet 40 and ring magnets 42 and 44 that are coaxially arranged as magnetized portions, and bosses that are adjacent in the radial direction. It has the connection part 48 which connects the part magnet 40 and the ring magnet 42, and connects the ring magnet 42 and the ring magnet 44, and is comprised. Further, the sensor magnet 36 is provided with a fixing ring 52 as a press-fit member constituting the magnet fixing structure 50.

  The boss magnet 40 is configured by magnetizing a disc-shaped boss 36 </ b> A that constitutes the axial center of the sensor magnet 36 with a predetermined magnetization pattern. The ring magnet 42 is formed in a ring shape whose inner diameter is larger than the outer diameter of the boss magnet 40, and the ring magnet 44 is formed in a ring shape whose inner diameter is larger than the outer diameter of the ring magnet 42. ing. Therefore, the boss magnet 40 and the ring magnets 42 and 44 are arranged to be separated from each other in the radial direction. The connecting portion 48 includes a plurality (three in this embodiment) of inner connecting portions 48A that connect the boss magnet 40 and the ring magnet 42, and a plurality (in this embodiment) that connects the ring magnet 42 and the ring magnet 44. Three) outer connecting portions 48B.

  Thereby, in the sensor magnet 36, the boss | hub part magnet 40 and the ring magnets 42 and 44 are comprised so that handling is possible, maintaining the relative relationship (relative position) of a mutual magnetization pattern. In other words, in this embodiment, the boss magnet 40 and the ring magnets 42 and 44 are magnetized in the respective magnetized patterns before the sensor magnet 36 is assembled to the worm wheel 20. In this embodiment, the magnetization pattern surfaces of the boss magnet 40 and the ring magnets 42 and 44 are located (exposed) on the same plane along the plane orthogonal to the axial direction of the output shaft 22. .

  Further, in the sensor magnet 36, the boss magnet 40 and the ring magnets 42 and 44 are coaxially arranged, and a plurality of inner coupling portions 48A and outer coupling portions 48B are arranged at equal intervals in the circumferential direction. Therefore, the center of gravity is substantially coincident with the axis (rotation center) of the worm wheel 20. Thereby, in the worm reduction gear 10, the rotation balance of the worm wheel 20 (that is, the output shaft 22) rotated integrally with the sensor magnet 36 is stabilized.

  The sensor magnet 36 described above is a so-called plastic magnet (bonded magnet) formed by including a magnetic powder in a resin material, and each part is integrally formed (in this embodiment, it is integrally molded). ing). As the magnetic powder, for example, a ferrite-based magnetic material, an alnico-based magnetic material, a neodymium-iron-boron-based magnetic material, a samarium-cobalt-based magnetic material, and the like can be used. Resin materials such as polypropylene and polyamide can be used. In this embodiment, the sensor magnet 36 is made of a material obtained by adding ferrite to nylon.

  The fixing ring 52 is made of a metal material, and is insert-molded at an axial center portion of the boss magnet 40 (disk-shaped boss portion 36A). Specifically, as shown in FIGS. 5A to 5C, the fixing ring 52 has a shape that prevents rotation with respect to the boss magnet 40 when it is insert-molded into a resin material. In the example of FIG. 5A, a plurality of protrusions 52B protrude radially from the outer periphery of a cylindrical ring main body 52A, and the fixing ring 52 becomes a boss portion by the resin material entering between the plurality of protrusions 52B. The rotation is prevented with respect to the magnet 40. In this case, the length of the ring body 52A in the axial direction is substantially equal to the thickness of the boss magnet 40 (both end faces of the cylindrical ring body 52A are exposed).

  In the example of FIG. 5B, a flange 52C is projected radially outward from one axial end of a cylindrical ring body 52A, and a plurality of holes or recesses 52D are formed in the flange 52C. The fixing ring 52 is prevented from rotating with respect to the boss magnet 40 by the resin material entering the plurality of holes or recesses 52D. In this, the flange 52C is embedded in the boss magnet 40, and only the other end of the ring body 52A in the axial direction is exposed.

  In the example of FIG. 5C, a flange 52E is projected radially outward from one end in the axial direction of a cylindrical ring body 52A, and a plurality of protrusions 52F project radially from the outer periphery of the flange 52E. The fixing ring 52 is prevented from rotating with respect to the boss magnet 40 by the resin material entering between the plurality of protrusions 52F. In this, the flange 52C is embedded in the boss magnet 40, and only the other end of the ring body 52A in the axial direction is exposed.

  As described above, the fixing ring 52 includes a ring main body 52A into which a convex portion 54, which will be described later, is press-fitted, and a rotation prevention structure (a plurality of protrusions 52B, 52A) for preventing relative rotation of the ring main body 52A with respect to the boss magnet 40. A flange 52C having a plurality of holes or recesses 52D and a flange 52E) having a plurality of projections 52F are provided. A structure other than the above may be employed as the rotation preventing structure. 2, 3, and 6 (FIGS. 9 and 10 according to the second embodiment), the illustration of the rotation prevention structure of the fixing ring 52 is omitted.

  The magnet fixing structure 50 fixes the sensor magnet 36 to the worm wheel 20 by press-fitting a metal convex portion 54 as a press-fitting portion provided on the worm wheel 20 into the ring body 52A of the magnet fixing structure 50. It is supposed to be.

  In this embodiment, the output shaft 22 fixed to the worm wheel 20 is made of metal, and the convex portion 54 is integrated with the output shaft 22 as shown in FIGS. 2 (A), 2 (B) and 3. Is formed. That is, the convex portion 54 protrudes coaxially from the end surface 22B of the output shaft 22 opposite to the tip 22A, and protrudes toward the sensor magnet 36 with respect to the end surface 20D of the boss portion 20C of the worm wheel 20. In other words, the convex portion 54 projects from the worm wheel 20 toward the side opposite to the cantilever support side of the output shaft 22 by the bearing 30. To supplement the structure for fixing the output shaft 22 to the worm wheel 20, a metal fixing ring 56 is fixed to the end of the output shaft 22 opposite to the tip 22 </ b> A by press fitting. Is embedded in the boss portion 20C of the worm wheel 20 by insert molding. A knurling process (not shown) is performed on the outer periphery of the fixing ring 56, and the output shaft 22 is fixed so as not to rotate relative to the worm wheel 20 as described above.

  The boss portion 20 </ b> C of the worm wheel 20 is formed as a circular thick wall portion when viewed from the bottom, which forms the axial center portion (fixed portion of the output shaft 22) of the worm wheel 20. It protrudes toward the sensor magnet 36 with respect to the portion 20C. The convex portion 54 is press-fitted into the fixing ring 52 provided at the axis of the sensor magnet 36 (boss portion magnet 40), so that the sensor magnet 36 rotates coaxially and integrally with the worm wheel 20 as described above. It is the structure fixed to. Although not shown, the tip of the convex portion 54 and the opening edge of the fixing ring 52 on the press-fitting side of the convex portion 54 are each chamfered or rounded. In this embodiment, the output shaft 22 of the wiper motor 11 also serves as the rotating shaft of the worm wheel 20, and corresponds to both the rotating shaft and the output shaft in the present invention.

  Further, the boss portion 20 </ b> C of the worm wheel 20 is formed with a recess 58 as a fitted portion. The recess 58 opens toward the one side in the axial direction of the worm wheel 20 (the protruding side of the projection 54) and the outside in the radial direction. In this embodiment, the shape of the edge is substantially semicircular (U-shaped). ). The concave portion 58 constitutes a positioning structure 60 with a convex portion 62 as an insertion portion provided in the sensor magnet 36.

  As shown in FIG. 4, the convex portion 62 is provided on the back side of the magnetized pattern surface of the boss magnet 40 in the boss portion 36 </ b> A of the sensor magnet 36. In this embodiment, the back surface side of the boss portion 36A of the sensor magnet 36 is a recess 64 in which a part of the boss portion 20C of the worm wheel 20 is fitted in a non-press-fit state. The convex portion 62 protrudes into the concave portion 64 so as to straddle the bottom wall 64A and the peripheral wall 64B of the concave portion 64. Therefore, the convex portion 62 is arranged away from the axis of the sensor magnet 36, that is, the worm wheel 20. In this embodiment, a single convex portion 62 is provided on the sensor magnet 36.

  Therefore, the convex part 62 which comprises the positioning structure 60 is arrange | positioned asymmetrically with respect to the axis line of the worm wheel 20. FIG. On the other hand, only one concave portion 58 of the worm wheel 20 (the same number as the convex portions 62) is formed. Accordingly, the positioning structure 60 is configured to uniquely determine the circumferential (rotation) direction position of the sensor magnet 36 with respect to the worm wheel 20 by fitting the convex portion 62 into the concave portion 58.

  In this embodiment, as shown in FIG. 2B, the protrusion height H1 (pressing stroke to the fixing ring 52) with respect to the end surface 20D of the convex portion 54 constituting the magnet fixing structure 50 is the bottom of the convex portion 62. The protrusion height H2 with respect to the wall 64A (the insertion stroke into the recess 58) is slightly larger. Therefore, in the worm reduction device 10, when the sensor magnet 36 is assembled to the worm wheel 20, first, the convex portion 54 is slightly inserted into the fixing ring 52 and the sensor magnet 36 is centered with respect to the worm wheel 20. Positioning in the circumferential direction is performed so that the convex portion 62 enters the concave portion 58.

  In addition, you may form the serration for rotation prevention etc. in the inner peripheral surface of the fixing ring 52 which comprises the magnet fixing structure 50, and the outer peripheral surface of the convex part 54. FIG.

  Next, the operation of the first embodiment will be described.

  In the wiper motor 11 to which the worm reduction device 10 having the above configuration is applied, when the motor main body 12 is driven, the worm 18 of the worm reduction device 10 is rotated around the own shaft together with the rotary shaft 16 and is engaged with the worm 18. The worm wheel 20 is rotated around its own axis. Since the output shaft 22 is fixed to the worm wheel 20, the output shaft 22 is rotated integrally with the worm wheel 20 at a rotational speed (amplified torque) reduced with respect to the rotational speed of the worm 18. .

  At this time, the sensor magnet 36 rotates integrally with the worm wheel 20 and outputs signals corresponding to the rotational position of the output shaft 22 to the Hall elements 38A to 38D. The control unit provided on the control board 34 controls the operation, stop, rotation direction, and the like of the motor body 12 based on a signal corresponding to the rotation position of the output shaft 22 from the Hall elements 38A to 38D.

  In assembling the sensor magnet 36 to the worm wheel 20 constituting the worm reduction device 10 described above, first, the tip of the convex portion 54 of the magnet fixing structure 50 is inserted into the fixing ring 52 (light press-fitting) to the worm wheel 20. On the other hand, the sensor magnet 36 is centered. Next, the circumferential position of the sensor magnet 36 is provisionally determined with respect to the worm wheel 20 by matching the circumferential positions of the concave portion 58 and the convex portion 62 of the positioning structure 60.

  From this state, the convex portion 62 is inserted into the concave portion 58 while the convex portion 54 is pressed into the fixing ring 52 further deeply. When the convex portion 54 is press-fitted into the fixing ring 52 until the end surface 20D of the boss portion 20C of the worm wheel 20 abuts (or extremely close to) the bottom wall 64A of the concave portion 64, the assembly of the sensor magnet 36 to the worm wheel 20 is completed. .

  Here, in the worm speed reduction device 10, the sensor protrusion 36 is fixed to the worm wheel 20 by pressing the metal protrusion 54 on the worm wheel 20 side into the metal fixing ring 52 on the sensor magnet 36 side. Has been. Therefore, in the worm reduction device 10, the sensor magnet 36 can be fixed to the worm wheel 20 so as not to rattle the worm wheel 20.

  As a result, the worm reduction device 10 projects from a worm wheel and, for example, as in a comparative example in which a toothed ring is fastened to the tips of a plurality of pins inserted into a plurality of holes formed in a sensor magnet. In order to prevent the sensor magnet from rattling against the worm wheel, excessive machining accuracy is not required. Therefore, the worm speed reduction device 10 is reduced in cost as compared with the comparative example, and the assembling property of the sensor magnet 36 to the worm wheel 20 is improved.

  In the worm reduction device 10, the sensor magnet 36 is not heated with the assembly of the sensor magnet 36 to the worm wheel 20. For this reason, in the worm speed reducer 10, the boss magnet 40 and the ring magnets 42 and 44 constituting the sensor magnet 36 are not deformed or demagnetized by heating. Therefore, in the worm reduction device 10, the magnetic sensor 38 outputs a highly accurate signal corresponding to the magnetic poles or magnetic fluxes of the boss magnet 40 and the ring magnets 42 and 44 that accompany the rotation (including the speed 0) of the sensor magnet 36. be able to.

  Moreover, in the worm reduction device 10, the sensor magnet 36 is assembled to the worm wheel 20 by press-fitting the metal members of the fixing ring 52 and the convex portion 54. For this reason, the fixing ring 52 and the convex portion 54 are firmly fixed while relaxing the stress acting on the boss magnet 40. Thereby, the boss magnet 40 which is a plastic magnet (bonded magnet) is prevented or effectively suppressed from cracking due to the assembly of the sensor magnet 36 with respect to the worm wheel 20. It is firmly assembled. Furthermore, since the stress acting on the boss magnet 40 is relieved with the assembly, it is possible to increase the magnetic force by increasing the amount of magnetic powder mixed into the resin material constituting the sensor magnet 36, for example.

  Thus, in the worm reduction device 10 according to the present embodiment, the sensor magnet 36 is fixed to the worm wheel 20 without rattling, and the rotational position of the output shaft 22 can be detected with high accuracy.

  In particular, in the worm reduction device 10, the sensor magnet 36 is configured to have ring magnets 42 and 44 having a different magnetization pattern from the boss magnet 40 in addition to the boss magnet 40. For this reason, the worm reduction device 10 can obtain signals corresponding to many rotational positions of the output shaft 22. Thereby, in the wiper motor 11 to which the worm speed reduction device 10 is applied, for example, as described above, a retracted position, a lower reversing position, an upper reversing position, and a plurality of other control positions (positions serving as a reference for control) are not shown. It is possible to set.

  Moreover, since the boss magnet 40 is formed by using the boss 36A which is a fixed portion of the sensor magnet 36 to the worm wheel 20, the worm reduction device 10 can obtain an equivalent rotational position signal 3 Compared to the heavy ring sensor magnet (comparative example), the number of ring magnets can be reduced and the size can be reduced. In other words, the worm reduction device 10 can obtain signals corresponding to many rotational positions of the output shaft 22 as described above while reducing the number of ring magnets as compared with the comparative example.

  Further, in the worm speed reduction device 10, the boss magnet 40 and the ring magnets 42 and 44 constituting the sensor magnet 36 are connected to each other via a connecting part 48. For this reason, the sensor magnet 36 can be assembled to the worm wheel 20 while maintaining the relative relationship (relative position) of the plurality of different magnetization patterns in the boss magnet 40 and the ring magnets 42 and 44. Thereby, in the worm speed reducer 10, the relative position errors of the plurality of magnetization patterns are not accumulated unlike the comparative example in which a plurality of different magnetization patterns are individually assembled to the worm wheel 20, and the output shaft This contributes to improving the detection accuracy of the rotation state.

  Further, in the worm reduction device 10, the magnetization pattern surfaces of the boss magnet 40 and the ring magnets 42 and 44 are located on the same plane along a plane orthogonal to the axial direction of the output shaft 22. For this reason, in the worm speed reducer 10, the polarities of the boss magnet 40 and the ring magnets 42 and 44 using the Hall elements 38A to 38D having substantially the same characteristics arranged on the common control board 34 (same plane). Alternatively, the rotational position can be detected based on the magnetic flux change.

  Furthermore, since the worm speed reduction device 10 includes the positioning structure 60, the position in the circumferential (rotation) direction of the sensor magnet 36 with respect to the worm wheel 20 can be uniquely determined. In particular, the convex portions 62 constituting the positioning structure 60 are asymmetrically arranged with respect to the axis of the worm wheel 20, and the same number of concave portions 58 into which the convex portions 62 can be fitted are provided on the worm wheel 20 side. Therefore, the position of the sensor magnet 36 in the circumferential direction with respect to the worm wheel 20 can be uniquely determined with a simple structure.

  For this reason, for example, a sensor magnet 36 magnetized in advance with a predetermined magnetizing pattern on a worm wheel 20 incorporated in the wiper motor 11 and having a normal / reverse rotation range is determined in a predetermined position in the rotational direction of the worm wheel 20. It can be fixed with high precision (relative position according to the position of the wiper arm). Further, in the worm reduction device 10, the magnet fixing structure 50 ensures that the sensor magnet 36 is fixedly held (relative rotation prohibiting function) with respect to the worm wheel 20, so that torque is supported by the concave portion 58 and the convex portion 62 of the positioning structure 60. There is nothing. For this reason, the recessed part 58 and the convex part 62 have a small required strength in the rotation direction and a high degree of freedom in setting.

  In the wiper motor 11 including the worm reduction device 10 as described above, the rotation state of the output shaft 22, that is, the operation state of the driven member (wiper arm or the like) can be detected with high accuracy.

  Here, in the worm reduction device 10, the sensor magnet 36 is fixed to a convex portion 54 that protrudes from the worm wheel 20 of the output shaft 22 to the side opposite to the cantilever support side by the bearing 30. For this reason, the control board 34 is disposed in the case 24 so that each magnetic sensor 38 and the control board 34 itself face the sensor magnet 36 without forming a through hole for allowing the output shaft 22 to pass therethrough. . As a result, circuit components and wiring can be effectively arranged on the control board 34, so that the control board 34 (outside shape) can be downsized, and thereby the control board 34 can be placed in a limited space in the case 24. It is easy to secure the arrangement space.

(Second Embodiment)
Next, a worm reduction device 70 according to a second embodiment of the present invention will be described with reference to FIGS. Note that parts and portions that are basically the same as those in the first embodiment may be denoted by the same reference numerals as those in the first embodiment, and may not be described or illustrated.

  FIG. 8 is a perspective view showing a state where the worm wheel 20 and the sensor magnet 36 constituting the worm reduction device 70 according to the second embodiment are separated. As shown in this figure, the worm speed reduction device 70 has a fitting hole 72 as a fitting portion provided on the sensor magnet 36 side, instead of the positioning structure 60 composed of the concave portion 58 and the convex portion 62, and the fitting hole 72. The worm reduction device 10 according to the first embodiment is different from the worm reduction device 10 according to the first embodiment in that it includes a positioning structure 75 including a convex portion 74 as a fitted portion on the worm wheel 20 side that can be fitted into the worm wheel 20.

  As shown in FIGS. 9 and 10, the fitting hole 72 is formed in a portion of the boss magnet 40 (boss portion 36 </ b> A) that is separated from the fixing ring 52. In this embodiment, the insertion hole 72 is a through-hole that penetrates the boss magnet 40 (the bottom wall 64A of the concave portion 64) in the protruding direction of the convex portion 54 (the press-fitting direction of the convex portion 54 and the fixing ring 52). Yes. Only one insertion hole 72 is formed. Therefore, the insertion hole 72 is disposed asymmetrically with respect to the axis of the worm wheel 20.

  The convex portion 74 is erected in parallel with the convex portion 54 from the boss portion 20 </ b> C of the worm wheel 20. In this embodiment, the convex portions 74 are provided in the same number as the insertion holes 72, that is, only one. Therefore, the positioning structure 75 is configured to uniquely determine the position in the circumferential (rotation) direction of the sensor magnet 36 with respect to the worm wheel 20 by inserting the convex portion 74 into the insertion hole 72. The protrusion 74 is inserted into the insertion hole 72 along with the press-fitting and fixing of the protrusion 54 and the fixing ring 52.

  In this embodiment, the protruding height of the convex portion 74 from the end surface 20D is substantially equal to the protruding height H1 of the convex portion 54 from the end surface 20D. Therefore, in the positioning structure 75, when the sensor magnet 36 is assembled to the worm wheel 20, the centering of the sensor magnet 36 with respect to the worm wheel 20 and the positioning in the circumferential direction are performed almost simultaneously. Other configurations of the worm reduction device 70 are the same as the corresponding configurations of the worm reduction device 10 including portions not shown.

  Therefore, the worm reduction device 70 according to the second embodiment and the wiper motor 11 to which the worm reduction device 70 is applied are basically the same as the worm reduction device 10 and the wiper motor 11 according to the first embodiment. The effect of can be obtained.

  In each of the above-described embodiments, the example in which the rotation position of the output shaft 22 is detected by the sensor magnet 36 and the magnetic sensor 38 has been described. However, the present invention is not limited to this, and for example, the rotation position of the output shaft 22 Instead of or in addition to the rotation position of the output shaft 22, the sensor magnet 36 and the magnetic sensor 38 may detect at least a part of the rotation direction, the presence / absence of rotation, the rotation speed, and the like of the output shaft 22.

  In each of the above-described embodiments, the gear device according to the present invention is applied to the wiper motor 11 as the worm reduction device 10. However, the present invention is not limited to this and is used for applications other than the wiper. It may be applied to a motor, and may be applied to a motor with a reduction gear other than a wiper motor using various reduction mechanisms such as a spur gear train, a hypoid gear, and a planetary gear train instead of a worm gear. The present invention may be applied to a power transmission mechanism, a speed increasing device, and the like. Further, the gear in the present invention is not limited to the configuration in which the output shaft 22 serves as the rotation shaft (the configuration in which the sensor magnet 36 is fixed to the final gear), and the first gear or the intermediate gear is used. The present invention may be applied to fix the sensor magnet 36. Even in this case, the rotational state of the output shaft 22 can be indirectly detected from the speed ratio (rotational speed ratio) between the gear and the output shaft 22.

  Furthermore, in each of the above-described embodiments, the example in which the magnet fixing structure 50 for press-fitting the convex portion 54 on the worm wheel 20 side into the fixing ring 52 on the sensor magnet 36 side is shown, but the present invention is not limited to this. For example, instead of the magnet fixing structure 50, insert molding is performed on the shaft center portion of the boss magnet 40 in the press-fit hole as the press-fit portion formed in the shaft center portion of the rotating shaft (output shaft 22) of the worm wheel 20. It is good also as a structure provided with the magnet fixing structure which press-fits the fixed protrusion member. Further, the press-fit portion on the worm wheel 20 side is not limited to the configuration provided on the output shaft 22, and may be a member fixed to the worm wheel 20 by insert molding, for example.

  Furthermore, in each of the above-described embodiments, the example in which the sensor magnet 36, which is preliminarily magnetized with a predetermined magnetization pattern as the magnetic member, is fixed to the worm wheel 20, but the present invention is not limited to this. For example, the sensor member 36 may be formed after the assembly by magnetizing the magnetic member after being assembled to the worm wheel 20 with a predetermined magnetization pattern.

  In each of the above embodiments, the sensor magnet 36 has two ring-shaped magnets 42 and 44. However, the present invention is not limited to this. For example, the sensor magnet 36 is used as a magnetized portion. It is good also as a structure provided only with the boss | hub part magnet 40, and it is good also as a structure provided with the boss | hub part magnet 40 and the 1 or 3 or more ring magnet. Further, the present invention is not limited to the configuration in which the magnetized pattern surfaces of the respective magnetized portions are arranged in the same plane. For example, a plurality of magnetized pattern surfaces are offset in the axial direction of the worm wheel 20. It is good also as a structure.

  Further, in each of the above-described embodiments, the positioning structure 60 and the positioning structure 75 each have one insertion portion and a fitted portion, so that a simple example of uniquely determining the circumferential position of the sensor magnet 36 with respect to the worm wheel 20 is determined. Although shown, the present invention is not limited to this. For example, a plurality of insertion portions are arranged or formed asymmetrically with respect to the axis of the worm wheel 20 (such as having different shapes), and the insertion portions corresponding to the insertion portions are provided. By providing the part on the worm wheel 20 side, the circumferential position of the sensor magnet 36 relative to the worm wheel 20 may be uniquely determined. Further, for example, in a configuration in which the sensor magnet 36 is fixed to the worm wheel 20 before being assembled to the wiper motor 11 or a configuration in which the worm wheel 20 rotates only in one direction, a configuration without the positioning structure 60 may be employed.

  Further, in each of the above-described embodiments, the convex portion 54 is integrally formed with one end portion of the output shaft 22 having a small diameter. However, the present invention is not limited to this, and for example, one end portion of the output shaft 22 (the worm wheel 20 On the other hand, the output shaft portion protruding to the opposite side of the cantilever support side) may be simply protruded from the worm wheel, and the fixing ring 52 of the sensor magnet 36 may be press-fitted and fixed to the protruding portion. As a result, the fixing surface with the fixing ring 52 is increased, so that the fixing can be more firmly fixed and processing for forming the convex portion 54 becomes unnecessary.

DESCRIPTION OF SYMBOLS 10 ... Worm speed reduction device (gear apparatus, speed reduction mechanism), 11 ... Wiper motor (motor with a reduction gear), 12 ... Motor main body, 14 ... Speed reduction part, 20 ... Worm wheel (gear), 22 ... Output shaft (gear rotation axis) ), 36 ... Sensor magnet (magnetic member), 38 ... Magnetic sensor, 40 ... Boss magnet (magnetized part), 42 · 44 ... Ring magnet (ring-shaped magnetized part), 48 ... Connecting part, 52 ... Fixing ring (press-fit member), 54 ... Convex part (press-fit part), 58 ... Concave part (fit part), 60 ... Positioning structure, 62 ... Convex part (insertion part), 70 ... Worm speed reducer (gear device, Deceleration mechanism), 72 ... Insertion hole (insertion part), 74 ... Convex part (insertion part), 75 ... Positioning structure

Claims (9)

A gear for transmitting rotation to the output shaft;
A magnetic member comprising a magnetic material and having a magnetized portion magnetized with a magnetizing pattern for directly or indirectly detecting the rotation state of the output shaft by a magnetic sensor;
A metal press-fit portion provided at one end of the rotation axis of the gear in the axial direction;
The magnetic member is fixed to the shaft center portion of the magnetized portion of the magnetic member by insert molding, and fixed to the press-fitting portion by press-fitting, so that the magnetic member is fixed so as to rotate coaxially and integrally with the gear. A metal press-fit member,
A gear device comprising: The rotating shaft of the gear is cantilevered rotatably at the other end side in the axial direction with respect to the gear,
2. The gear device according to claim 1, wherein one end of the press-fitting portion in the axial direction of the rotating shaft protrudes from the gear toward a side opposite to the cantilever support side with respect to the gear.   The magnetic member is arranged coaxially on the outer peripheral portion of the magnetized portion to which the press-fitted member is fixed, and has a magnetization pattern that is different from the magnetized portion to which the press-fitted member is fixed in the rotation direction. The gear device according to claim 1 or 2, further comprising at least one ring-shaped magnetized portion to be magnetized.   The magnetic member has a plurality of the magnetized parts spaced apart in the radial direction and connected so that the magnetized parts arranged adjacent to each other in the radial direction rotate coaxially and integrally. The gear device according to claim 3, further comprising a connected portion.   5. The magnetic member according to claim 3, wherein at least two magnetization pattern surfaces among the magnetization pattern surfaces of the plurality of magnetized portions are located on the same plane perpendicular to the axis of the rotation axis. The gear device described.   The gear device according to any one of claims 1 to 5, further comprising a positioning structure for positioning the magnetic member in a circumferential direction with respect to the gear. The positioning structure is
A fitting portion that is recessed or protruded from the gear side in the magnetized portion of the magnetic member so as to be asymmetric with respect to the axis of the rotating shaft;
The same number of protrusions or recesses as the insertion portion from the magnetic member side in the gear, and the insertion portion into which the insertion portion is inserted,
The gear device according to claim 6, comprising: A motor section;
A reduction gear configured by applying the gear device according to any one of claims 1 to 7 as at least a part of a reduction mechanism that decelerates the rotation of the motor and transmits the rotation to the output shaft;
A motor with a speed reducer for driving a driven part connected to the output shaft. The deceleration part is
A gear device according to any one of claims 2 to 5 or any one of claims 6 and 7 dependent on claim 2 reduces the rotation of the motor unit. And is configured to be applied as at least a part of a speed reduction mechanism that transmits to the output shaft,
A case for accommodating the speed reduction mechanism including the gear device;
A control circuit for drivingly controlling the rotation of the magnetic sensor and the motor unit is provided, and the magnetic sensor is moved to the magnetic member without penetrating the rotating shaft on the protruding side of the press-fitting portion with respect to the gear in the case. And a control board arranged to face the magnetic member,
The motor with a reduction gear according to claim 8, comprising:

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