JP2011244562A - Motor with reduction gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an operation failure of a motor with a reduction gear by firmly fixing a sensor magnet to a side of a speed reduction gear without using a different component.SOLUTION: A circular sensor magnet 33 constituting a rotation position detection sensor 32 is fixed to a side 22a of a resin worm wheel 22 constituting the reduction gear. For fixing the sensor magnet 33, a circular holding wall 41 concentric with an output shaft 14 is integrally formed on the side 22a of the worm wheel 22. The sensor magnet 33 is formed in a circular shape with a plastic magnet and a step 42 is formed at a peripheral portion. The sensor magnet 33 is integrated to an inner side of the holding wall 41. A tip portion of the holding wall 41 is pushed toward the step 42 while it is heated by a heat jig. The tip portion is welded to the step 42 and the step 42 is locked by a locking portion 46 formed after cooling.

Description

  The present invention relates to a motor with a speed reducer that is a single unit by attaching a speed reducer to an electric motor, and in particular, a sensor magnet for detecting a rotational position of an output shaft is fixed to a side surface of a speed reduction gear constituting the speed reducer. About.

  As a drive source for a wiper device, a power window device, a sunroof device, etc. provided in a vehicle, there is a motor with a speed reducer as a unit by attaching a speed reducer to an electric motor operated by a power source such as a battery mounted on the vehicle. It is used.

  As a speed reducer used for a motor with a speed reducer, a worm gear mechanism that is small and can obtain a large reduction ratio is often used. The worm gear mechanism includes a worm and a worm wheel that meshes with the worm. The worm is provided on the motor shaft of the electric motor, and the worm wheel is fixed to the output shaft of the speed reducer.

  On the other hand, some motors with a reduction gear are provided with a rotational position detection sensor for detecting the rotational position of the output shaft in order to control the operation thereof. The rotational position detection sensor includes an annular sensor magnet fixed to the side surface of the worm wheel (reduction gear) and a magnetic sensor disposed opposite to the sensor magnet, and a plurality of magnetic poles surround the sensor magnet. They are magnetized side by side. When the electric motor is operated, the sensor magnet rotates together with the worm wheel, and the change of the magnetic pole is detected by the magnetic sensor. When a change in the magnetic pole is detected by the magnetic sensor, the rotational position of the output shaft is detected based on the detection result, and the driven device such as the wiper device is electrically operated based on the rotational position. The operation control of the motor is performed.

  By the way, in a motor with a reduction gear equipped with a rotational position detection sensor, it is necessary to securely fix the sensor magnet to the side surface of the worm wheel (deceleration gear) in order to increase the detection accuracy of the rotational position detection sensor. For this reason, various methods have been proposed for fixing the sensor magnet to the worm wheel.

  For example, in Patent Document 1, an inner peripheral surface of a sensor magnet is engaged with an outer peripheral surface of a holding wall provided on a worm wheel, and the holding wall is welded to the sensor magnet so that the sensor magnet is fixed to the side surface of the worm wheel. The structure is described.

  Further, in Patent Document 2, an insertion hole is provided in the sensor magnet, and the fixing protrusion provided on the worm wheel is inserted into the insertion hole of the sensor magnet disposed on the side surface of the worm wheel, and the toothed ring is tightened on the fixing protrusion. A structure in which the sensor magnet is fixed to the side surface of the worm wheel by wearing is described.

JP 2005-094821 A JP 2008-253121 A

  However, in the fixing structure of Patent Document 1, since the worm wheel and the sensor magnet are made of different materials, it is difficult to obtain a sufficient fixing strength by welding. Therefore, in some cases, the sensor magnet has a backlash with respect to the worm wheel, thereby causing an error in detection of the rotational position of the output shaft, and there is a possibility that the performance of the motor with a reduction gear is greatly deteriorated.

  On the other hand, the structure of Patent Document 2 can increase the fixing strength of the sensor magnet to the worm wheel, but since a toothed ring is used separately from the worm wheel and the sensor magnet, the number of parts and weight increase. In addition, there is a problem that the assembly becomes complicated.

  An object of the present invention is to make it possible to firmly fix a sensor magnet to a side surface of a reduction gear without using a separate part, and to reduce malfunction of a motor with a reduction gear.

  The motor with a speed reducer of the present invention is a motor with a speed reducer provided with an electric motor and a speed reducer that decelerates the output of the electric motor and outputs it from an output shaft, and is fixed to the output shaft. A resin-made reduction gear, an annular concentric ring with the output shaft, a resin-made holding wall provided integrally with the reduction gear on the side surface of the reduction gear, and a plurality of magnetic poles in the circumferential direction A sensor magnet which is magnetized side by side and is fixed to the side surface of the reduction gear with the outer peripheral portion being in contact with the inner peripheral surface of the holding wall, and is disposed opposite to the sensor magnet, and changes in the magnetic poles of the sensor magnet And a magnetic sensor for detecting the rotational position of the output shaft, a stepped portion is provided on an outer peripheral portion of the sensor magnet, and the holding wall is engaged with the stepped portion by welding so as to attach the sensor magnet to the reduction gear. Side of Wherein the fixed thing.

  In the motor with a reduction gear according to the present invention, the stepped portion is formed in a belt shape that protrudes radially outward from the outer peripheral surface of the sensor magnet and extends over the entire circumference of the outer peripheral surface, and the axial direction of the stepped portion A plurality of concave portions are provided in the circumferential direction on both side surfaces facing the surface.

  The motor with a speed reducer according to the present invention is characterized in that the sensor magnet is formed in a line-symmetric shape with respect to an axial center.

  The motor with a speed reducer according to the present invention is provided with a central projecting portion, which is disposed inside the sensor magnet and accommodates the base end portion of the output shaft, integrally provided on a side surface of the reduction gear. The protruding height of the sensor magnet is set lower than the protruding height of the central protruding portion from the side surface, and a gap is provided between the inner peripheral surface of the sensor magnet and the outer peripheral surface of the central protruding portion. It is characterized by.

  According to the present invention, the holding wall provided on the side surface of the reduction gear is engaged with the outer peripheral portion of the sensor magnet by welding so that the sensor magnet is fixed to the side surface of the reduction gear. Compared with the case where the sensor magnet is fixed by the above, the fixing strength of the sensor magnet to the reduction gear can be increased. In addition, since a step portion is provided on the outer peripheral portion of the sensor magnet, and a holding wall provided on the side surface of the reduction gear is engaged with the step portion by welding, the sensor magnet is fixed to the side surface of the reduction gear. The fixing strength of the sensor magnet to the reduction gear can be increased. As described above, the sensor magnet can be firmly fixed to the side surface of the reduction gear without using another component, and the malfunction of the motor with the reduction gear can be reduced. In addition, since the sensor magnet can be firmly fixed to the side surface of the reduction gear without using separate parts, the number of parts of the motor with a reduction gear can be reduced and the assembly work can be facilitated. The cost can be reduced.

  According to the present invention, the step portion is formed in a belt shape that protrudes radially outward from the outer peripheral surface of the sensor magnet and extends over the entire circumference of the outer peripheral surface, and is formed on both side surfaces facing the axial direction of the step portion. Since the plurality of recesses are provided at equal intervals in the circumferential direction, the holding wall is securely engaged with the stepped portion to further increase the fixing strength of the sensor magnet in the axial direction, and the holding wall is welded to the recess. By engaging, the fixing strength of the sensor magnet in the rotation direction can be further increased.

  According to the present invention, since the sensor magnet is formed in a line-symmetric shape with respect to the axial center, the sensor magnet is assembled to the reduction gear by eliminating the mounting direction in the axial direction of the sensor magnet. It is possible to prevent the direction difference from occurring.

  According to the present invention, the central protrusion that accommodates the base end portion of the output shaft is integrally provided on the side surface of the reduction gear, and the protrusion height of the sensor magnet from the side surface of the reduction gear is lower than the protrusion height of the central protrusion portion. Since a gap is provided between the inner peripheral surface of the sensor magnet and the outer peripheral surface of the central projecting portion, even if the housing portion is thermally expanded due to a thermal shock or the like, the load due to the expansion is applied to the sensor magnet. It is possible to prevent the sensor magnet from cracking.

It is a partially cutaway sectional view of a motor with a reduction gear according to an embodiment of the present invention. It is a front view which shows the internal structure of the reduction gear of the motor with a reduction gear shown in FIG. It is an expanded sectional view of the part of the worm wheel of the reduction gear shown in FIG. It is a front view which shows the control board attached to the cover body shown in FIG. It is a perspective view which shows the detail of the sensor magnet shown in FIG. (A) is a top view of the sensor magnet shown in FIG. 5, (b) is the same front view. It is sectional drawing which shows the state before the sensor magnet of the worm wheel shown in FIG. 3 is fixed. (A)-(c) is explanatory drawing which shows the procedure which engages a holding | maintenance wall with the level | step-difference part of a sensor magnet by welding, respectively.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  A motor 11 with a reduction gear according to an embodiment of the present invention shown in FIG. 1 is used as a drive source of a wiper device mounted on an automobile, that is, a wiper motor.

  The motor 11 with a speed reducer includes an electric motor 12 and a speed reducer 13, and the speed reducer 13 is attached to the electric motor 12 to form one unit. A motor with a brush is used as the electric motor 12, and the motor shaft 12a rotates in a predetermined direction.

  In the present embodiment, a motor with a brush is used as the electric motor 12. However, the present invention is not limited to this, and other types of electric motors such as a brushless DC motor may be used.

  The speed reducer 13 decelerates the output of the electric motor 12 at a predetermined reduction ratio and outputs it from the output shaft 14. As shown in FIG. 2, a worm gear mechanism 16 is provided inside a gear case 15 formed in a bathtub shape. It has a housed structure. The gear case 15 is fixed to the opening of the yoke 12 b of the electric motor 12 using a screw member 17, whereby the speed reducer 13 is attached to the electric motor 12. A cover body 18 is attached to the opening of the gear case 15, and the opening of the gear case 15 is closed by the cover body 18.

  The worm gear mechanism 16 includes a worm 21 and a worm wheel 22 as a reduction gear that meshes with the worm 21. The motor shaft 12a of the electric motor 12 protrudes into the gear case 15, and the worm 21 is integrally formed on the outer peripheral surface of the portion accommodated in the gear case 15 of the motor shaft 12a. On the other hand, the worm wheel 22 that is a reduction gear is made of a resin that is formed in a substantially disk shape by a resin material such as POM plastic (acetal plastic mainly composed of polyoxymethylene), and its axial center. In FIG. 3, the base end of the output shaft 14 of the speed reducer 13 is fixed. The output shaft 14 is rotatably supported by the boss portion 15 a of the gear case 15, whereby the worm wheel 22 is rotatable inside the gear case 15 together with the output shaft 14.

  With this configuration, when the electric motor 12 operates and the motor shaft 12a rotates, the rotation is decelerated to a predetermined number of rotations by the worm 21 and the worm wheel 22 and is output from the output shaft 14. The distal end of the output shaft 14 protrudes outside from the boss portion 15a of the gear case 15, and a link mechanism of a wiper device (not shown) is connected to the distal end.

  As shown in FIG. 1, a control board 23 is accommodated in the gear case 15, and the operation control of the electric motor 12 is performed by the control board 23. The control board 23 has a structure in which a plurality of electronic components (not shown) such as a CPU (central processing unit) and a memory are mounted on the board. As shown in FIG. It is fixed. The cover body 18 is fixed to the gear case 15, so that the control board 23 is accommodated in the gear case 15 in a state of facing the side surface 22 a facing the axial direction of the worm wheel 22. In addition, the control board 23 is connected to the electric motor 12 at the power supply terminal 23a, and is connected to a wiper switch (not shown) or an in-vehicle battery (power source) via a connector 18a provided on the cover body 18.

  As shown in FIG. 1, the motor 11 with a speed reducer is provided with a rotation sensor 31 that detects the rotation speed of the motor shaft 12a and a rotation position detection sensor 32 that detects the rotation position of the output shaft 14. The detection signals of these sensors 31 and 32 are input to the control board 23, and the control board 23 determines the rotational speed of the motor shaft 12 a and the rotational position of the output shaft 14 based on the detection signals input from these sensors 31 and 32. Is supposed to be detected. That is, when the wiper switch is operated and a command signal from the wiper switch is input to the control board 23, the control board 23 receives inputs from the rotation sensor 31 and the rotational position detection sensor 32 in addition to the command signal from the wiper switch. The operation control of the electric motor 12 is executed on the basis of the rotational speed of the motor shaft 12a detected by the above and the rotational position of the output shaft 14.

  Next, a detailed configuration of the rotational position detection sensor 32 will be described.

  As shown in FIGS. 2 and 3, the rotational position detection sensor 32 includes a sensor magnet 33 and a magnetic sensor 34.

  The sensor magnet 33 is formed in an annular shape, and is fixed to the side surface 22 a of the worm wheel 22 on the side facing the control substrate 23. As shown in FIG. 2, two magnetic poles (N pole and S pole) are magnetized side by side in the circumferential direction on the side surface 33 a facing the axial direction of the sensor magnet 33. In the illustrated case, the N pole is magnetized in a predetermined range (90 °) in the circumferential direction of the side surface 33a of the sensor magnet 33, and the S pole is magnetized in the remaining range.

  On the other hand, the magnetic sensor 34 is mounted at a predetermined position of the control board 23, and when the cover body 18 to which the control board 23 is fixed is fixed to the gear case 15, it faces the sensor magnet 33 with a predetermined interval. It has become. As the magnetic sensor 34, a Hall element (Hall IC) that reacts to changes in magnetic poles is used. The magnetic sensor 34 outputs a detection signal toward the control board 23 when the magnetic poles of the opposing portions change due to rotation of the sensor magnet 33. In the case shown in the figure, when the wiper arm constituting the wiper device is in the lower inversion position, that is, the stop position, the magnetic sensor 34 faces the N pole of the sensor magnet 33 and outputs a detection signal. That is, the control board 23 can detect that the rotational position of the output shaft 14 has reached the position where the wiper device is set to the stop position based on the detection signal input from the magnetic sensor 34. Thus, even when the wiper switch is turned off at random timing, the control board 23 maintains the operation of the electric motor 12 until the wiper device is at the stop position, and the wiper device is at the stop position. Sometimes, control to stop the electric motor 12 can be performed.

  Next, a structure for fixing the sensor magnet 33 constituting the rotational position detection sensor 32 to the side surface 22a of the worm wheel 22 will be described.

  In the present invention, in order to increase the fixing strength of the sensor magnet 33 to the side surface 22 a of the worm wheel 22, the holding wall 41 is provided on the side surface 22 a of the worm wheel 22, and the sensor magnet 33 is fitted inside the holding wall 41. A step portion 42 is provided on the outer peripheral portion of the sensor magnet 33, and the holding wall 41 is engaged with the step portion 42 by welding.

  The holding wall 41 provided on the side surface 22 a of the worm wheel 22 is formed of a resin material integrally with the worm wheel 22 on the side surface 22 a of the worm wheel 22. That is, the holding wall 41 is made of resin. The holding wall 41 has a wall shape protruding in the axial direction from the side surface 22a of the worm wheel 22 and is formed in an annular shape concentric with the worm wheel 22. As shown in FIG. It is set to be the same as or slightly smaller than the outer diameter D2 of the sensor magnet 33.

  A central protrusion 43 is provided on the side surface 22 a of the worm wheel 22 in addition to the holding wall 41, and the base end of the output shaft 14 is accommodated in the central protrusion 43. The central projecting portion 43 is formed of a resin material integrally with the worm wheel 22, is formed in a dome shape concentric with the worm wheel 22, and is disposed on the axis of the worm wheel 22. As shown in FIG. 3, the projection height h1 of the central protrusion 43 in the axial direction from the side surface 22a of the worm wheel 22 is the axial projection from the side surface 22a of the sensor magnet 33 fixed to the side surface 22a. It is set higher than the height h2.

  Further, as shown in FIG. 7, the outer diameter dimension D <b> 3 of the central protrusion 43 is set smaller than the inner diameter dimension D <b> 4 of the sensor magnet 33. Thereby, as shown in FIG. 3, a gap is provided between the inner peripheral surface of the sensor magnet 33 fixed to the worm wheel 22 and the outer peripheral surface of the central protrusion 43. By providing such a gap, even if the central protrusion 43 is thermally expanded in the radial direction due to thermal shock or the like, it is possible to prevent a load due to the expansion from being transmitted to the sensor magnet 33. Thereby, it can prevent that the sensor magnet 33 receives a load from the center protrusion part 43 which thermally expanded, and is cracked.

  The sensor magnet 33 used for the rotational position detection sensor 32 is formed in an annular shape by injection molding a resin material containing magnetic powder. That is, the sensor magnet 33 is a plastic magnet. As the resin material for forming the sensor magnet 33, polyamide resin, polyphenylene sulfide resin, polypropylene resin, or the like is used. Examples of magnetic powders contained in these resin materials include ferrite, alnico, and samarium. -Cobalt type, neodymium-iron-boron type are used.

  Here, as shown in FIG. 6A, a flat cutout portion 44 is provided on the outer periphery of the sensor magnet 33, and the sensor magnet 33 is injection-molded with a resin material containing a magnetic material. At this time, an injection gate for injecting the resin material is arranged toward the cutout portion 44 of the sensor magnet 33. That is, the injection gate is not arranged on the side surface 33 a facing the axial direction of the sensor magnet 33 that faces the magnetic sensor 34. Thereby, even if the magnetic properties of the sensor magnet 33 in the portion corresponding to the gate for injection deteriorate, the sensing accuracy by the magnetic sensor 34 is adversely affected without causing the deteriorated portion to face the magnetic sensor 34. Can be prevented.

  As shown in FIGS. 5 and 6, the outer peripheral surface 33b of the sensor magnet 33 is parallel to the axial direction, and the stepped portion 42 provided on the outer peripheral portion of the sensor magnet 33 is directed radially outward from the outer peripheral surface 33b. It is formed in the shape of a band having a rectangular cross section that protrudes over the entire circumference of the outer peripheral surface 33b. Both side surfaces 42 a facing the axial direction of the stepped portion 42 are arranged so as to be perpendicular to the axial direction and offset from the side surface 33 a facing the axial direction of the sensor magnet 33 in the axial direction. Thereby, the cross-sectional shape of the sensor magnet 33 is a convex shape in which the stepped portion 42 protrudes radially outward from the outer peripheral surface 33b.

  In addition, a plurality of concave portions 42b are provided on both side surfaces 42a of the step portion 42 so as to be arranged at equal intervals in the circumferential direction. Each of the recesses 42b has a predetermined width in the circumferential direction and is formed in a shape recessed from the both side surfaces 42a of the stepped portion 42 in the axial direction, and also on the outer peripheral surface 42c side of the stepped portion 42. It is open. That is, these recesses 42b are formed in a shape in which both side surfaces 42a of the stepped portion 42 are cut out with a predetermined width in the circumferential direction.

  As shown in FIGS. 6A and 6B, the sensor magnet 33 uses a reference line L passing through the center in the axial direction and a reference line R passing through the center in the radial direction as a reference. It is formed in a line-symmetric shape with a sandwich. Further, the cutout portion 44 of the sensor magnet 33 is disposed at a position that does not adversely affect the side surface 33a and the concave portion 42b. Thereby, the assembly direction of the sensor magnet 33 with respect to the worm wheel 22 is not limited to either the front or back side in the axial direction and the radial direction. As a result, the direction of assembly of the sensor magnet 33 in the axial direction and the radial direction can be eliminated, and a difference in the direction of assembly of the sensor magnet 33 to the worm wheel 22 can be prevented, thus facilitating the assembly work. Can be.

  The sensor magnet 33 is assembled from the axial direction in a space formed between the holding wall 41 of the side surface 22 a of the worm wheel 22 and the central protrusion 43. At this time, since the outer diameter D2 of the sensor magnet 33 and the inner diameter D1 of the holding wall 41 are the same or the outer dimension D2 is set to be slightly smaller than the inner diameter D1, the sensor magnet 33 has an outer peripheral portion. Is fitted into the inner peripheral surface of the holding wall 41.

  When the sensor magnet 33 is incorporated inside the holding wall 41, the tip end portion in the axial direction of the holding wall 41 is engaged with the stepped portion 42 of the sensor magnet 33 by welding. This welding is performed by heat caulking in which a tip portion of the holding wall 41 is thermally deformed toward the stepped portion 42 by using a heat jig (not shown).

  Next, a procedure for welding the tip end portion of the holding wall 41 to the stepped portion 42 will be described with reference to FIGS.

  When the sensor magnet 33 is fitted inside the holding wall 41 from the axial direction, the side surface 33a facing the axial direction of the sensor magnet 33 contacts the side surface 22a of the worm wheel 22 as shown in FIG. At the same time, the outer peripheral surface, that is, the outer peripheral surface 42 c of the stepped portion 42 abuts against the inner peripheral surface of the holding wall 41 and is positioned on the side surface 22 a of the worm wheel 22. That is, the sensor magnet 33 is positioned on the side surface 22 a of the worm wheel 22 by the holding wall 41 at the outer peripheral portion thereof. At this time, the tip end portion of the holding wall 41 in the axial direction protrudes outward in the axial direction from the side surface 42 a of the stepped portion 42 of the sensor magnet 33.

  When the sensor magnet 33 is positioned by the holding wall 41, next, as shown in FIG. 8B, the tip portion of the holding wall 41 is heated by a heating jig, and the tip portion softened by heating is radially inward. It is deformed by heat so as to be pressed and bent and is pressed toward the side surface 42 a of the stepped portion 42. When the distal end portion of the holding wall 41 is pressed against the step portion 42 by thermal deformation, the distal end portion is welded so as to be continuous with the step portion 42 of the sensor magnet 33 mainly composed of a resin material. Thereby, the step part 42 of the sensor magnet 33 is fixed to the holding wall 41 by welding.

  The thermal deformation of the tip portion of the holding wall 41 is performed over the entire circumference in the circumferential direction. Further, a tapered surface 45 is formed on the outer peripheral surface side of the tip portion of the holding wall 41 before welding, so that the tip portion of the holding wall 41 can be easily thermally deformed.

  When the front end portion of the holding wall 41 pressed against the step portion 42 due to thermal deformation is cooled after welding, the front end portion of the holding wall 41 maintained in the bent state is held as shown in FIG. The engaging portion 46 protrudes radially inward from the wall 41 and engages with the side surface 42 a of the step portion 42 of the sensor magnet 33. As a result, the sensor magnet 33 is sandwiched between the engaging portion 46 that engages the side surface 42 a of the stepped portion 42 and the side surface 22 a of the worm wheel 22, and is fixed in the axial direction with respect to the worm wheel 22.

  At this time, the locking portion 46 is disposed in a range between the side surface 42a of the step portion 42 of the sensor magnet 33 and the side surface 33a of the sensor magnet 33 so as not to protrude outward in the axial direction from the side surface 33a of the sensor magnet 33. It has become. Thereby, when the worm wheel 22 rotates, the locking portion 46 does not protrude from the side surface 33a of the sensor magnet 33 in the axial direction and interfere with the magnetic sensor 34.

  Further, a part of the front end portion of the holding wall 41 pressed against the side surface 42 a of the step portion 42 by thermal deformation is pushed into the recess 42 b provided on the side surface 42 a of the step portion 42. And the latching | locking part 46 will also be engaged with the recessed part 42b by cooling the pushed part. As a result, the sensor magnet 33 is more firmly fixed (locked) by the locking portion 46 in the circumferential direction.

  As described above, in the motor 11 with a reduction gear according to the present invention, the sensor magnet 33 has the holding wall 41 welded to the step portion 42 provided on the outer peripheral portion thereof, and the holding wall 41 is engaged with the step portion 42. By joining, it is firmly fixed to the side surface 22a of the worm wheel 22. Therefore, it is possible to prevent the fixed position of the sensor magnet 33 with respect to the worm wheel 22 from being shifted, thereby improving the detection accuracy of the rotational position detection sensor 32 and improving the operation accuracy of the motor 11 with a reduction gear.

  As described above, in the motor 11 with the speed reducer, the sensor magnet 33 is welded and engaged with the holding wall 41 provided on the side surface 22a of the worm wheel 22 at the outer peripheral portion thereof. The strength of fixing the sensor magnet 33 to the side surface 22a of the worm wheel 22 can be increased as compared with the case where the sensor magnet 33 is welded and engaged with the holding wall. Further, a step portion 42 is provided on the outer peripheral portion of the sensor magnet 33, and a holding wall 41 provided on the side surface 22 a of the worm wheel 22 is engaged with the step portion 42 by welding so that the sensor magnet 33 is attached to the side surface of the worm wheel 22. Since it was fixed to 22a, compared with the case where the level | step-difference part 42 is not provided, the fixing strength of the sensor magnet 33 by the holding wall 41 can be raised. Therefore, the sensor magnet 33 can be firmly fixed to the side surface 22a of the worm wheel 22 without using another part such as a fastening member. And the malfunction of the motor 11 with a reduction gear can be reduced by firmly fixing the sensor magnet 33 to the side surface 22a of the worm wheel 22.

  Further, since the sensor magnet 33 can be firmly fixed to the side surface 22a of the worm wheel 22 without using another part such as a fastening member, the number of parts of the motor 11 with a speed reducer can be reduced and the assembling work can be reduced. Can be easily. Thereby, the cost for manufacturing this motor 11 with a reduction gear can be reduced.

  Further, the step portion 42 provided on the outer peripheral portion of the sensor magnet 33 protrudes from the outer peripheral surface 33b of the sensor magnet 33 toward the radially outer side, and is formed in a belt shape extending over the entire circumference of the outer peripheral surface 33b. Since the plurality of recesses 42b are provided at equal intervals in the circumferential direction on both side surfaces 42a facing the axial direction of 42, the sensor magnet 33 is securely engaged by the locking portions 46 formed by thermal deformation on the holding wall 41. Can be stopped. Thereby, the fixing strength to the side surface 22a of the worm wheel 22 of the sensor magnet 33 using the holding wall 41 can be further increased.

  It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, although the worm gear mechanism 16 is used for the speed reducer 13 in the above-described embodiment, the speed reducer 13 is not limited thereto, and includes a speed reduction gear to which an output shaft is fixed, such as a speed reduction gear train including a plurality of spur gears. As long as it is a thing, you may make it use the deceleration mechanism of another type.

  In the above embodiment, a Hall element (Hall IC) is used as the magnetic sensor 34. However, the present invention is not limited to this, and it can detect a change in the magnetic pole of the sensor magnet 33 fixed to the worm wheel 22. If present, another magnetic sensor may be used.

  Furthermore, in the said embodiment, although the shape of the sensor magnet 33 was made into the annular | circular shape, the sensor magnet 33 is welded to the holding wall 41 provided in the worm wheel 22 in the outer peripheral part of the sensor magnet 33, Any shape that engages may be used.

  Furthermore, in the above-described embodiment, the plurality of concave portions 42b are provided on both side surfaces 42a of the stepped portion 42 so as to be arranged at equal intervals in the circumferential direction. It is not necessary to arrange them at equal intervals in the direction. Each of the plurality of recesses 42b has a predetermined width in the circumferential direction, but the width can be arbitrarily determined without being equally spaced.

  Furthermore, in the above-described embodiment, heat welding is used as means for welding the holding wall 41 to the stepped portion 42 of the sensor magnet 33. However, the present invention is not limited to this, and for example, the holding wall 41 using ultrasonic waves is used. Other welding methods may be used, such as ultrasonic welding for heating the plate and vibration welding for heating the holding wall 41 by applying vibration.

DESCRIPTION OF SYMBOLS 11 Motor with reduction gear 12 Electric motor 12a Motor shaft 12b Yoke 13 Reduction gear 14 Output shaft 15 Gear case 15a Boss part 16 Worm gear mechanism 17 Screw member 18 Cover body 18a Connector 21 Worm 22 Worm wheel (reduction gear)
22a side surface 23 control board 23a power supply terminal 24 screw member 31 rotation sensor 32 rotation position detection sensor 33 sensor magnet 33a side surface 33b outer peripheral surface 34 magnetic sensor 41 holding wall 42 stepped portion 42a side surface 42b concave portion 42c outer peripheral surface 43 central projecting portion 44 notch Part 45 Tapered surface 46 Locking part D1 Inner diameter of holding wall D2 Outer diameter of sensor magnet h1 Projection height of central protrusion h2 Projection height of sensor magnet D3 Outer diameter of central protrusion D4 Inner diameter of sensor magnet L reference line R reference line

Claims (4)

A motor with a speed reducer comprising an electric motor and a speed reducer that decelerates the output of the electric motor and outputs it from an output shaft,
A resin-made reduction gear fixed to the output shaft and constituting the reduction gear;
A resin-made holding wall formed in an annular shape concentric with the output shaft, and provided integrally with the reduction gear on a side surface of the reduction gear;
A plurality of magnetic poles arranged side by side in the circumferential direction, and a sensor magnet fixed to the side surface of the reduction gear by bringing the outer peripheral portion into contact with the inner peripheral surface of the holding wall;
A magnetic sensor disposed opposite to the sensor magnet and detecting a rotational position of the output shaft from a change in magnetic pole of the sensor magnet;
A motor with a reduction gear, wherein a step portion is provided on an outer peripheral portion of the sensor magnet, and the holding wall is engaged with the step portion by welding to fix the sensor magnet to a side surface of the reduction gear.   The motor with a speed reducer according to claim 1, wherein the stepped portion is formed in a belt shape that protrudes radially outward from the outer peripheral surface of the sensor magnet and extends over the entire circumference of the outer peripheral surface. A motor with a speed reducer, characterized in that a plurality of recesses are provided in the circumferential direction on both side surfaces facing the axial direction.   3. The motor with a speed reducer according to claim 2, wherein the sensor magnet is formed in a line-symmetric shape with respect to an axial center.   The motor with a speed reducer according to any one of claims 1 to 3, wherein a central projecting portion that is disposed inside the sensor magnet and accommodates a base end portion of the output shaft is integrated with a side surface of the speed reduction gear. And the projecting height of the sensor magnet from the side surface of the reduction gear is set lower than the projecting height of the central projecting portion from the side surface, and the inner peripheral surface of the sensor magnet and the outer periphery of the central projecting portion A motor with a speed reducer, characterized in that a gap is provided between the surface and the surface.

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