JP4393825B2 - Electric motor with reduction mechanism - Google Patents

Description

  The present invention relates to an electric motor with a speed reduction mechanism that is unitized by attaching a speed reduction mechanism to a motor body, and more particularly to a motor in which a magnet that is a detected member of a rotational position detection sensor is fixed to a speed reduction gear.

  As a drive source for a wiper device, a power window device, a sunroof device or the like provided in a vehicle, an electric motor that is operated by a power source such as a battery mounted on the vehicle is usually used. In order to adapt the electric motor to these devices, it is necessary to reduce the rotation of the motor to a required number of rotations. For this reason, such an electric motor is provided with a gear-type reduction mechanism and is formed as one unit as an electric motor with a reduction mechanism, and is also referred to as a geared motor because a gear-type reduction mechanism is attached.

  In such an electric motor with a speed reduction mechanism, the speed reduction mechanism is housed in a gear case fixed to the housing of the motor body, and a worm gear mechanism that is small and can provide a large reduction ratio is often used as the speed reduction mechanism. . In this case, a worm is integrally formed on the outer periphery of the portion of the rotating shaft that protrudes into the gear case, and the worm wheel that meshes with the worm is rotatably accommodated in the gear case. Further, an output shaft is fixed to the shaft center of the worm wheel, and a tip end portion of the output shaft protrudes from the gear case and is connected to the driven member. As a result, the rotation of the rotating shaft is decelerated by the worm gear mechanism and output from the output shaft, and the output is transmitted to the driven member.

In such an electric motor with a speed reduction mechanism, for example, as disclosed in Patent Document 1, a rotation position detection sensor for detecting the rotation position of the output shaft is provided, and the rotation position of the output shaft detected by the rotation position detection sensor is provided. There is known one that controls the operation of the motor body based on the above. In this case, the rotational position detection sensor has a magnet fixed to the side surface of the worm wheel and a magnetic sensor such as a hall element facing the magnet, and the magnet is fixed to the side surface of the reduction gear using an adhesive. It is designed to rotate with the worm wheel. The change in the magnetic pole of the magnet rotating with the worm wheel, that is, the output shaft is detected by a Hall element, and the rotational position of the output shaft is detected from the period and the number of pulses of the detection signal.
JP-A-4-306152 (page 3-4, FIG. 1)

  However, in the above-described electric motor with a speed reduction mechanism, the magnet is bonded to the worm wheel using an adhesive, so that it takes a long time for the adhesive to harden and complete fixing, and the number of work in progress increases. This will increase the manufacturing cost. Further, the worm gear is often formed of POM plastic (acetal plastic mainly composed of polyoxymethylene or the like), and in this case, it has been difficult to obtain sufficient adhesive strength with an adhesive.

  On the other hand, there is known a so-called snap-fit fixing method in which a claw portion that engages with a magnet is provided on the side surface of the worm gear, and the magnet is locked and fixed by this claw portion. However, in this fixing method, since the shape of the worm gear is complicated because the claw portion is provided, the manufacturing cost thereof may be increased, and the accuracy of the gear portion may be reduced.

  Further, in this fixing method, a slight backlash occurs between the claw portion and the magnet, so that there is a limit to the positioning accuracy of the magnet. For this reason, the fixed position of the magnet may deviate from the specified position and the detection accuracy of the rotational position of the output shaft by the rotational position detection sensor may be reduced. When this electric motor with a speed reduction mechanism is used in a wiper device, the wiper arm There was a risk of problems such as the stop position shifting and obstructing the driver's view.

  An object of the present invention is to increase the accuracy of operation of an electric motor with a speed reduction mechanism.

An electric motor with a speed reduction mechanism according to the present invention is an electric motor with a speed reduction mechanism having a motor body having a rotation shaft and a speed reduction mechanism that decelerates rotation of the rotation shaft and outputs it from an output shaft. A resin-made reduction gear fixed to the output shaft, a magnet formed in an annular shape by a resin containing magnetic powder, and fixed to a side surface of the reduction gear; and a side surface of the reduction gear And an annular holding wall that holds the magnet in contact with the inner or outer peripheral surface of the magnet, and faces the magnet, and detects the rotational position of the output shaft from the change in the magnetic pole of the magnet. And the magnet is fixed to the reduction gear by welding.

The electric motor with a speed reduction mechanism according to the present invention is characterized in that a notch portion is formed on an end surface of the magnet, and a tip end portion of the holding wall is welded to the notch portion .

The electric motor with a speed reduction mechanism according to the present invention is an electric motor with a speed reduction mechanism having a motor body having a rotation shaft and a speed reduction mechanism for reducing the rotation of the rotation shaft and transmitting the rotation to the output shaft. A resin-made reduction gear fixed to the output shaft, a magnet holder formed of resin and fixed to a side surface of the reduction gear, and a magnet held by the magnet holder and rotating together with the reduction gear; A magnetic sensor that faces the magnet and detects a rotational position of the output shaft from a change in magnetic pole of the magnet, and the magnet holder has a main body that holds the magnet and a leg that protrudes from the main body. And inserting the leg portion into a through hole formed in the reduction gear, and welding the tip end portion of the leg portion to the reduction gear. The sandwich the reduction gear between the end of the leg portion and characterized in that it is fixed to the reduction gear.

  The electric motor with a speed reduction mechanism according to the present invention is characterized in that a wall portion for positioning the magnet holder is provided on the speed reduction gear.

An electric motor with a speed reduction mechanism according to the present invention is an electric motor with a speed reduction mechanism having a motor body having a rotation shaft and a speed reduction mechanism that decelerates rotation of the rotation shaft and outputs it from an output shaft. A resin-made reduction gear fixed to the output shaft, a magnet fixed to a side surface of the reduction gear, and a side surface of the reduction gear, provided integrally with an inner peripheral surface or an outer peripheral surface of the magnet; contact with the annular retaining wall for holding the magnet, the aforementioned magnet facing, and a magnetic sensor for detecting a rotational position of the output shaft from the change of the magnetic poles of the magnet, the tip of the front Symbol retaining wall wherein The magnet is fixed to the reduction gear by being thermally deformed to the magnet side.

  According to the present invention, since the magnet can be securely fixed to the reduction gear, the detection accuracy of the rotational position detection sensor can be increased, and the operation accuracy of the electric motor with the reduction mechanism can be increased.

  Further, according to the present invention, the strength of fixing the magnet to the reduction gear can be increased.

  Furthermore, according to the present invention, since the magnet can be fixed to the reduction gear in a short time, the manufacturing cost of the electric motor with the reduction mechanism can be reduced.

  Furthermore, according to the present invention, since the structure of the reduction gear can be simplified, the accuracy of the gear portion of the reduction gear can be improved.

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

  FIG. 1 is an explanatory view showing an outline of a wiper device using an electric motor with a speed reduction mechanism according to an embodiment of the present invention. In the vehicle 11 shown in FIG. A wiper device 13 is provided to secure the driver's field of view by wiping off the splashes.

  The wiper device 13 has two wiper shafts 14a and 14b that are rotatably supported by the vehicle 11. A wiper shaft 14a is fixed with a wiper arm 15a on the driver side, that is, on the DR side, and a wiper shaft 14b has an assistant. The seat side, that is, AS-side wiper arm 15b is fixed. Further, the wiper blade 16a on the driver's seat side, that is, the DR side, is attached to the tip of the wiper arm 15a on the DR side, and the wiper blade 16b on the passenger side, that is, the AS side, is attached to the tip of the wiper arm 15b on the AS side. Each wiper blade 16a, 16b is pressed against the windshield 12 by a pressing force applied by a spring (not shown) built in the wiper arms 15a, 15b. A link mechanism 17 is connected to the wiper shafts 14a and 14b. When the crank arm 17a of the link mechanism 17 is rotated, the wiper shafts 14a and 14b are swung within a predetermined angular range. Then, when the wiper shafts 14a and 14b are swung, the wiper blades 16a and 16b are swung in the wiping ranges 12a and 12b between the upper reversing position and the lower reversing position on the windshield 12, and the windshield 12 is moved. It has come to be wiped out.

  The wiper device 13 is provided with an electric motor 21 with a speed reduction mechanism as its drive source. The electric motor 21 with a speed reduction mechanism is fixed to the vehicle 11 as a wiper device constituted by a link mechanism or the like, and the crank arm 17a is rotationally driven by the electric motor 21 with a speed reduction mechanism.

  2 is a partially cutaway sectional view showing details of the electric motor with a speed reduction mechanism shown in FIG. 1, and FIG. 3 is a front view showing details of the inside of the case body shown in FIG. 4 is a cross-sectional view showing details of the worm wheel shown in FIG.

  The electric motor 21 with a speed reduction mechanism is also called a wiper motor, and has a motor main body 22 and a speed reducer 23 attached to the motor main body 22 as shown in FIG. The motor body 22 is a so-called brushed electric motor, and includes a rotating shaft 22b protruding from the housing 22a, an armature coil (not shown), a field magnet, a commutator, a brush, and the like housed in the housing 22a. The rotary shaft 22b is rotated by a direct current supplied from a battery (power source) (not shown) mounted on the vehicle 11.

  In the illustrated case, the motor body 22 is an electric motor with a brush. However, the present invention is not limited to this, and other types of electric motors such as a brushless DC motor may be used.

  On the other hand, the speed reducer 23 has a speed reduction mechanism 24 and a gear case 25 that houses the speed reduction mechanism 24, and the gear case 25 is attached to the motor main body 22 by being fixed to the housing 22 a of the motor main body 22. The gear case 25 includes a case body 26 formed in a bathtub shape and a closing cover 27. The case body 26 accommodates the speed reduction mechanism 24, and the closing cover 27 is fixed to the case body 26 to close the case body 26. It is supposed to be. Further, a seal member 28 is provided at an engaging portion between the case body 26 and the closing cover 27, and the case body 26 is sealed by the closing cover 27 by providing the seal member 28. . In the illustrated case, as the sealing member 28, a liquid packing (sealant) such as butyl rubber applied to a sealing groove 27a formed in the closing cover 27 is used, and the case body 26 and the closing cover 27 at the time of maintenance or the like are used. It is easy to disassemble.

  The seal member 28 is not limited to liquid packing, but may be formed of other materials such as rubber packing formed of solid rubber.

  As shown in FIG. 3, the speed reduction mechanism 24 housed in the case body 26 is a worm gear mechanism having a worm 31 and a worm wheel 32 that meshes with the worm 31, and the worm 31 projects into the case body 26. The rotating shaft 22b is integrally formed on the outer periphery of the rotating shaft 22b and is rotated by the rotating shaft 22b. The worm wheel 32, which is a reduction gear of the reduction mechanism 24, is formed in a substantially disc shape from POM plastic (acetal plastic mainly composed of polyoxymethylene) as a resin. It is fixed to the proximal end portion of the output shaft 33 at the center. The output shaft 33 is rotatably supported by a boss portion 26 a formed on the case body 26, so that the worm wheel 32 is rotatable inside the case body 26 together with the output shaft 33. Further, for example, grease is applied as a lubricant to a meshing portion between the worm 31 and the worm wheel 32 so that the operation of the speed reduction mechanism 24 is made smooth. In this case, grease is used as the lubricant. However, the present invention is not limited to this, and a solid, semi-solid, or liquid lubricant may be used.

  The distal end portion of the output shaft 33 protrudes outside from the gear case 25, and the aforementioned crank arm 17a is fixed to the distal end portion. With this structure, when the rotary shaft 22b rotates, the rotation is decelerated by the speed reduction mechanism 24 and output from the output shaft 33, and the crank arm 17a is rotationally driven. Reference numeral 34 denotes a bearing 34 mounted between the boss portion 26 a and the output shaft 33, and reference numeral 35 denotes a pressing ring 35 that restricts the movement of the output shaft 33 in the axial direction.

  As shown in FIG. 2, a control board 41 is accommodated in the gear case 25 of the electric motor 21 with a speed reduction mechanism, and the control of the operation of the motor body 22 is performed by the control board 41. .

  FIG. 5 is a front view showing the details of the control board shown in FIG. 2, and this control board 41 is fixed to the inside of the closing cover 27 by a fastening member 42, and as shown in FIG. The casing 32 is accommodated inside the case body 26 so as to face the side surface of the foil 32. The control board 41 has a plurality of electronic components (not shown) such as a CPU and a memory and functions as a so-called microcomputer. The control board 41 is connected to the motor main body 22 via the power supply terminal 43 and is provided in the gear case 25. It is connected to a wiper switch (not shown) or a battery (power source) mounted on the vehicle via the coupler 44. When a command signal from the wiper switch is input, a direct current is supplied to the motor main body 22 according to the command signal to control the operation of the motor main body 22. Further, as shown in FIG. 2, a heat sink 45 having a plurality of fins 45a is provided on the outer surface side of the closing cover 27, and heat generated by the control board 41 is released by the heat sink 45 to the outside. It has become.

  The electric motor 21 with a speed reduction mechanism is provided with a rotation sensor 51 and a rotation position detection sensor 52, and the control board 41 controls the operation of the motor body 22 based on the detection signals of these sensors 51 and 52. It has become.

  As shown in FIG. 2, the rotation sensor 51 includes an annular magnet 53 fixed to the rotation shaft 22 b and a magnetic sensor 54 mounted on the control board 41 and facing the magnet 53, and this magnetic sensor 54. Thus, the rotational speed of the rotary shaft 22b is detected. The magnet 53 is a multi-pole magnetized magnet in which a plurality of magnetic poles are magnetized side by side in the circumferential direction, and the magnetic pole facing the magnetic sensor 54 changes as the rotating shaft 22b rotates. On the other hand, a Hall element that outputs a detection signal in response to a change in the magnetic pole is used as the magnetic sensor 54, and a detection signal having a period corresponding to the rotation of the rotating shaft 22b, that is, the change in the magnetic pole of the opposing magnet 53 is output. It is supposed to be. And the detection signal of the magnetic sensor 54 is input into the control board 41, and the control board 41 recognizes the rotation speed of the rotating shaft 22b from the period of the input detection signal. As a result, the control board 41 can control the operation of the motor main body 22 based on the rotational speed of the rotary shaft 22b. The wiping speed of the wiper blades 16a and 16b can be controlled by rotating the motor 22 at a constant rotational speed.

  As shown in FIG. 3, the rotational position detection sensor 52 includes an annular magnet 56 fixed to the side surface 55 of the worm wheel 32, which is a reduction gear, on the side facing the control board 41, and as shown in FIG. A magnetic sensor 57 is mounted on the control board 41 and faces the magnet 56, and the rotational position of the output shaft 33 is detected by the magnetic sensor 57. As shown in FIG. 3, the N pole is magnetized in a predetermined range (65 °) in the circumferential direction on the side surface of the magnet 56 facing the control board 41, and the S pole is magnetized in the remaining range. As the foil 32 rotates, the magnetic pole facing the magnetic sensor 57 changes. On the other hand, a Hall element that reacts to changes in the magnetic pole is used as the magnetic sensor 57. In this case, a detection signal is output when the magnetic pole of the magnet 56 changes from the S pole to the N pole. The detection signal of the magnetic sensor 57 is input to the control board 41, and the control board 41 can recognize the rotational position of the output shaft 33 when the magnetic sensor 57 faces the N pole of the magnet 56 from the input signal. It is like that. In this case, the rotation position of the output shaft 33 when the magnetic sensor 57 faces the N pole of the magnet 56 is a stop position where the wiper arms 15a and 15b are in the downward reversal position. It can be detected that the rotational position of 33 has become the stop position, that is, that the wiper arms 15a and 15b have been turned to the lower reverse position. Therefore, the control board 41 controls the motor body 22 based on the detection signal of the magnetic sensor 57, so that the wiper arm can be operated even when the wiper switch is randomly turned off regardless of the position of the wiper arms 15a and 15b. 15a and 15b can always be stopped at the lower inversion position.

  Since the rotational position detection sensor 52 detects the rotational position of the output shaft 33 by the magnet 56 and the magnetic sensor 57 fixed to the side surface 55 of the worm wheel 32, the fixed position of the magnet 56 with respect to the worm wheel 32. If the position is shifted, the stop positions of the wiper arms 15a and 15b are shifted from the lower reverse position to cause problems such as hindering the driver's view. For this reason, in the electric motor 21 with a speed reduction mechanism, the magnet 56 is fixed to the worm wheel 32 by welding so as to increase the fixing strength of the magnet 56.

  6 is a cross-sectional view showing a state before the magnet of the worm wheel shown in FIG. 4 is fixed, and FIG. 7 is a cross-sectional view showing details of a welded portion between the magnet and the worm wheel.

  The magnet 56 used in the rotational position detection sensor 52 is a so-called plastic magnet formed in an annular shape with a resin containing magnetic powder. Examples of the powder include ferrite-based, alnico-based, and samarium- Cobalt-based, neodymium-iron-boron-based magnetic materials are used, and as the resin, polyamide resin, polyphenylene sulfide resin, polypropylene resin, or the like is used. Further, on the inner peripheral side of the end surface of the magnet 56 on the side facing the control substrate 41, a cutout portion 56a that is cut out to have a larger diameter than the inner peripheral surface is formed.

  In the case shown in the figure, the magnet 56 is formed in an annular shape. However, the present invention is not limited to this, and other shapes may be used as long as the rotational position of the output shaft 33 is detected by the magnetic sensor 57. Good.

  On the other hand, as shown in FIG. 6, an annular holding wall 62 having an outer diameter corresponding to the inner diameter of the magnet 56 and protruding in the axial direction is integrally provided on the side surface 55 of the worm wheel 32. Is fitted to the outside of the holding wall 62 in the radial direction. The magnet 56 fitted in the holding wall 62 has one axial end surface in contact with the side surface 55 of the worm wheel 32 and its inner peripheral surface in contact with the holding wall 62. It is designed to be positioned. At this time, as indicated by a broken line in FIG. 7, the distal end portion of the holding wall 62 protrudes outward in the axial direction from the other end surface of the magnet 56.

  In the illustrated case, the holding wall 62 is formed so as to be in contact with the inner peripheral surface of the magnet 56, but is not limited thereto, and may be formed so as to be in contact with the outer peripheral surface of the magnet 56, When the magnet 56 is not formed in an annular shape, it may be formed in a shape corresponding to that.

  The front end portion of the holding wall 62 is a welded portion 63, and the magnet 56 is fixed to the worm wheel 32 by welding the welded portion 63 to the notch portion 56 a of the magnet 56. That is, the welded portion 63 provided at the distal end portion of the holding wall 62 is heated and softened, bent outward, and pressed against the notch 56a, so that the softened welded portion 63 is mutually attached to the notch 56a of the magnet 56. Joined for continuity. Such welding of the welded portion 63 may be anything as long as heat is applied to deform the welded portion 63 and the magnet 56 is fixed.

  Further, since the welded portion 63 is welded in a state of being bent toward the notch portion 56a, and thereafter cooled and maintained in a bent state, the magnet 56 is maintained at the notched portion 56a in the welded portion 63 and the worm wheel 32. Between the side surface 55 and the holding wall 62.

  Accordingly, the magnet 56 is held by the holding wall 62 and is firmly fixed to the worm wheel 32 by welding. Therefore, the fixing position of the magnet 56 with respect to the worm wheel 32 is not shifted, the detection accuracy of the rotational position detection sensor 52 is improved, and the operation accuracy of the electric motor 21 with the speed reduction mechanism is increased.

  As described above, in the electric motor 21 with the speed reduction mechanism, the magnet 56 is firmly fixed to the worm wheel 32 by welding, so that the displacement of the fixing position with respect to the worm wheel 32 is suppressed. Therefore, the magnet 56 is fixed to the worm wheel 32 with high positional accuracy, and the detection accuracy of the rotational position detection sensor 52 can be improved and the operation accuracy of the electric motor 21 with the speed reduction mechanism can be increased.

  Further, since the magnet 56 can be fixed to the worm wheel 32 in a short time by welding, the process setting is facilitated, and the manufacturing cost of the electric motor 21 with the speed reduction mechanism can be reduced.

  Furthermore, since it is not necessary to form a claw portion or the like for fixing the magnet 56 to the worm wheel 32, the structure can be simplified and the manufacturing cost of the worm wheel 32 can be reduced. Moreover, since the structure of the worm wheel 32 is simplified, the accuracy of the gear portion of the worm wheel 32 can be improved.

  8 is a cross-sectional view showing a modification of the worm wheel shown in FIG. 6, and FIG. 9 is a cross-sectional view showing a state where the magnet of the worm wheel shown in FIG. 8 is fixed.

  The worm wheel 64 shown in FIG. 8 is made of resin, and a welded portion 66 is provided on the side surface 65 thereof. In this case, the welded portion 66 is formed in a triangular shape whose cross section protrudes in the axial direction and is formed in an annular shape corresponding to the magnet 56, and when the magnet 56 is welded, it is shown in FIG. In this manner, the magnet 56 is pressed and deformed so as to spread over the entire end surface of the magnet 56. Thus, the welded portion 66 provided on the worm wheel 64 is not limited to the welded portion 63 provided at the distal end portion of the holding wall 62 shown in FIG. That's fine. Such welding of the welding part 66 is performed by ultrasonic welding for heating the welding part 66 using ultrasonic waves, vibration welding for welding by applying vibration, thermal welding for directly applying heat to the welding part 66, or the like.

  Further, in the worm wheels 32 and 64 shown in FIGS. 6 and 8, the magnet 56 formed of a resin containing magnetic powder is directly welded to the welding portions 61 and 66 provided in the worm wheels 32 and 64. However, the present invention is not limited to this, and the magnet may be held by a magnet holder made of resin, and the magnet holder may be fixed to a resin worm wheel by welding. For example, FIG. 10 is a cross-sectional view showing a modified example of the worm wheel shown in FIG. 6, and FIG. 11 is a cross-sectional view showing a state in which the holder of the worm wheel shown in FIG. 10 is fixed. Are provided with a main body 72 for holding the magnet 56 and a plurality of legs 73 protruding in the axial direction from the main body 72, while the worm wheel 74 has a plurality of through holes 74 a penetrating in the axial direction. Is provided. And when fixing the magnet holder 71 to the worm wheel 74, first, each leg part 73 is penetrated to the corresponding through-hole 74a. As indicated by a broken line in FIG. 11, in a state where the magnet holder 71 is set on the worm wheel 74, the distal end portion of each leg portion 73 protrudes from the opening portion of the through hole 74a. Next, the distal end portion of the leg portion 73 is softened by applying heat, and the softened distal end portion of the leg portion 73 is pressed against a concave locking portion 75 formed on the worm wheel 74. As a result, the distal end portion of the leg portion 73 is deformed into a head 76 having a larger diameter than the through hole 74 a and is in contact with the locking portion 75 and welded to the locking portion 75. Therefore, the magnet holder 71 decelerates in a state in which the worm wheel 74 is sandwiched between the head portion 76 formed at the distal end portion of the leg portion 73 and the main body portion 72 and the head portion 76 is welded to the locking portion 75. It is firmly fixed to the side surface of the worm wheel 74 that is a gear. Thus, even when the magnet 56 is fixed to the worm wheel 74 via the magnet holder 71, the magnet 56 held by the magnet holder 71 can be warmed by fixing the magnet holder 71 to the worm wheel 74 by welding. It can be firmly fixed to the foil 74.

  In this case, the magnet 56 may be formed of a magnetic material, or may be formed of a resin containing magnetic powder.

  Further, as shown by a one-dot chain line in FIG. 11, a wall 77 that contacts the outer peripheral surface of the magnet holder 71 may be provided on the side surface of the worm wheel 74, and the wall 77 magnet holder 71 may be positioned. In this case, a welding portion as shown in FIG. 8 may be provided on the side surface of the worm wheel 74, and the magnet holder 71 may be directly welded to the welding portion.

  Thus, in the electric motor 21 with the speed reduction mechanism, the magnet holder 71 that holds the magnet 56 is fixed to the worm wheel 74 by welding, so that the magnet 56 is firmly attached to the worm wheel 74 via the magnet holder 71. Can be fixed. Therefore, the fixing position of the magnet 56 with respect to the worm wheel 74 is not shifted, the accuracy of the rotational position detection sensor 52 is improved, and the operation accuracy of the electric motor 21 with the speed reduction mechanism can be increased.

  In FIGS. 8 to 11, members corresponding to those described above are denoted by the same reference numerals.

  12 is a cross-sectional view schematically showing the state of attachment of the cover shown in FIG. 2, and FIG. 13 is a perspective view showing details of the cover shown in FIG. As shown in FIG. 12, a cover 81 is provided between the speed reduction mechanism 24 and the control board 41 inside the gear case 25 of the electric motor 21 with the speed reduction mechanism, and the control board 41 and the speed reduction mechanism 24 are provided. Is in a shielding state by the cover 81.

  As shown in FIG. 13, the cover 81 has a separation wall portion 81a formed in a flat plate shape, and the case body so that the separation wall portion 81a is parallel to the rotating shaft 22b and faces the side surface 55 of the worm wheel 32. 26 is fixed. Therefore, even if the grease applied to the meshed portion of the worm 31 and the worm wheel 32 is scattered by the operation of the speed reduction mechanism 24, the cover 81 prevents the scattered grease from adhering to the control board 41.

  Further, the outer peripheral end portion 81 b of the cover 81 is bent at a right angle with respect to the isolation wall portion 81 a, and the outer peripheral end portion 81 b is a seal member provided at the engaging portion between the case body 26 and the closing cover 27. 28 is engaged with the inner side of the case body 26. As a result, the outer peripheral end portion 81 b of the cover 81 is engaged with the gear case 25 in a sealed state, and the grease melted by the heat generated by the motor main body 22 and the control board 41 travels along the inner wall of the gear case 25 and the control board 41. Even if it flows to the side, grease does not leak from the space between the outer peripheral end 81b of the cover 81 and the gear case 25 to the control board 41 side.

  Thus, in this electric motor 21 with a speed reduction mechanism, the control board 41 is isolated from the speed reduction mechanism 24 by the cover 81, so that the lubricant applied to the speed reduction mechanism can be prevented from adhering to the control board. . Further, since the outer peripheral end 81b of the cover 81 is engaged with the seal member 28 provided at the engaging portion between the case body 26 and the closing cover 27 constituting the gear case 25, the outer periphery of the gear case 25 and the cover 81 is engaged. Leakage of grease from between the end portions 81b can be prevented. Therefore, grease does not adhere to electronic components and sensors mounted on the control board 41, and the operation reliability of the electric motor 21 with a speed reduction mechanism can be improved.

  In addition, since the space between the cover 81 and the gear case 25 is sealed using the sealing member 28 that seals the case body 26 and the closing case 27, the number of parts and assembly steps of the sealing member 28 are reduced. The cost of the electric motor 21 with the speed reduction mechanism is reduced.

  Thus, in this electric motor 21 with a speed reduction mechanism, leakage of grease from between the gear case 25 and the cover 81 is prevented using the seal member 28 provided at the engaging portion between the case body 26 and the closing cover 27. Since it did in this way, the number of parts and the assembly man-hour of the sealing member 28 can be reduced, and the cost of this electric motor 21 with a reduction mechanism can be reduced.

  FIG. 14 is a cross-sectional view schematically showing a modification of the cover shown in FIG. 12, and the cover 91 shown in FIG. 14 is provided with an annular engagement wall 92 that protrudes from the isolation wall portion 81a in the right angle direction. It has been. In this case, the case body 26 is formed with an annular engagement groove 93 over the entire circumference of the case body 26 outside the worm wheel 32, and the engagement wall 92 of the cover 91 is engaged with the engagement groove 93. It is supposed to be. As a result, an engagement portion between the engagement wall 92 and the engagement groove 93 is formed between the cover 91 and the gear case 25, and is melted by the heat generated by the motor body 22 and the control board 41. Even if the grease flowing along the inner wall of the gear case 25 reaches between the cover 91 and the gear case 25, it does not leak out to the control board 41 side.

  As described above, in the electric motor 21 with the speed reduction mechanism, the engagement portion between the engagement wall 92 and the engagement groove 93 is provided between the cover 91 and the gear case 25, and therefore, between the gear case 25 and the cover 91. Leakage of grease can be prevented. Therefore, the lubricant does not adhere to the electronic components and sensors mounted on the control board 41, and the operation reliability of the electric motor 21 with the speed reduction mechanism can be improved.

  In the illustrated case, the engagement wall 92 is provided in the cover 91 and the engagement groove 93 is provided in the case body 26. However, the present invention is not limited to this, and the engagement wall 92 provided in the cover 91 and The engaging groove 93 to be engaged may be provided in the closing cover 27, or the engaging groove 93 may be provided in the cover 91, and the engaging wall 92 that engages with the engaging groove 93 may be provided in the case body 26 or the closing cover 27. .

  12 to 14, members corresponding to the members described above are denoted by the same reference numerals.

  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, in the above embodiment, a worm gear mechanism is used as the speed reduction mechanism 24. However, the speed reduction mechanism 24 is not limited thereto, and includes a speed reduction gear to which an output shaft is fixed, such as a speed reduction gear train composed of a plurality of spur gears. Any other type of speed reduction mechanism may be used.

  In the above embodiment, a Hall element is used as the magnetic sensor 57. However, the present invention is not limited to this, and any other element can be used as long as it can detect a change in the magnetic pole of the magnet 56 fixed to the worm wheel 32. A magnetic sensor may be used.

It is explanatory drawing which shows the outline of the wiper apparatus with which the electric motor with a reduction mechanism which is one embodiment of this invention was used. It is a partially cutaway sectional view showing details of the electric motor with a speed reduction mechanism shown in FIG. It is a front view which shows the detail inside the case body shown in FIG. It is sectional drawing which shows the detail of the worm wheel shown in FIG. It is a front view which shows the detail of the control board shown in FIG. It is sectional drawing which shows the state before the magnet of the worm wheel shown in FIG. 4 is fixed. It is sectional drawing which shows the detail of the welding part of a magnet and a worm wheel. It is sectional drawing which shows the modification of the worm wheel shown in FIG. It is sectional drawing which shows the state by which the magnet of the worm wheel shown in FIG. 8 was fixed. It is sectional drawing which shows the modification of the worm wheel shown in FIG. It is sectional drawing which shows the state by which the holder of the worm wheel shown in FIG. 10 was fixed. It is sectional drawing which shows typically the attachment state of the cover shown in FIG. It is a perspective view which shows the detail of the cover shown in FIG. It is sectional drawing which shows typically the modification of the cover shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Vehicle 12 Windshield 12a, 12b Wiping range 13 Wiper device 14a, 14b Wiper shaft 15a DR side wiper arm 15b AS side wiper arm 16a DR side wiper blade 16b AS side wiper blade 17 Link mechanism 17a Crank arm 21 With reduction mechanism Electric motor 22 Motor body 22a Housing 22b Rotating shaft 23 Reduction gear 24 Reduction mechanism 25 Gear case 26 Case body 26a Boss portion 27 Closure cover 27a Seal groove 28 Seal member 31 Warm 32 Warm wheel (reduction gear)
33 Output shaft 34 Bearing 35 Press ring 41 Control board 42 Fastening member 43 Power supply terminal 44 Coupler 45 Heat sink 45a Fin 51 Rotation sensor 52 Rotation position detection sensor 53 Magnet 54 Magnetic sensor 55 Side surface 56 Magnet 56a Notch 57 Magnetic sensor 62 Holding wall 63 welding portion 64 worm wheel 65 side surface 66 welding portion 71 magnet holder 72 main body portion 73 leg portion 74 worm wheel 74a through hole 75 locking portion 76 head 77 wall portion 81 cover 81a isolation wall portion 81b outer peripheral end portion 91 cover 92 engagement Abutment wall 93 engagement groove

Claims (5)

An electric motor with a speed reduction mechanism having a motor body having a rotation shaft and a speed reduction mechanism for reducing the rotation of the rotation shaft and outputting from the output shaft,
A reduction gear made of resin provided in the reduction mechanism and fixed to the output shaft;
A magnet formed in an annular shape from a resin containing magnetic powder, and fixed to a side surface of the reduction gear;
An annular holding wall that is integrally provided on a side surface of the reduction gear and that holds the magnet in contact with the inner or outer peripheral surface of the magnet;
A magnetic sensor that faces the magnet and detects a rotational position of the output shaft from a change in magnetic pole of the magnet;
An electric motor with a speed reduction mechanism, wherein the magnet is fixed to the speed reduction gear by welding. 2. The electric motor with a speed reduction mechanism according to claim 1, wherein a notch portion is formed on an end surface of the magnet, and a tip end portion of the holding wall is welded to the notch portion . An electric motor with a speed reduction mechanism having a motor body having a rotation shaft and a speed reduction mechanism for reducing the rotation of the rotation shaft and transmitting the rotation to the output shaft,
A reduction gear made of resin provided in the reduction mechanism and fixed to the output shaft;
A magnet holder formed of resin and fixed to a side surface of the reduction gear;
A magnet held by the magnet holder and rotating together with the reduction gear;
A magnetic sensor that faces the magnet and detects a rotational position of the output shaft from a change in magnetic pole of the magnet;
The magnet holder includes a main body portion for holding the magnet and a leg portion protruding from the main body portion, the leg portion is inserted into a through hole formed in the reduction gear, and a distal end portion of the leg portion is reduced to the speed reduction gear. An electric motor with a speed reduction mechanism , wherein the speed reduction gear is sandwiched between the main body portion and the tip end portion of the leg portion and fixed to the speed reduction gear by welding to the gear .   4. The electric motor with a speed reduction mechanism according to claim 3, wherein a wall portion for positioning the magnet holder is provided on the speed reduction gear. An electric motor with a speed reduction mechanism having a motor body having a rotation shaft and a speed reduction mechanism for reducing the rotation of the rotation shaft and outputting from the output shaft,
A reduction gear made of resin provided in the reduction mechanism and fixed to the output shaft;
A magnet fixed to a side surface of the reduction gear;
An annular holding wall that is integrally provided on a side surface of the reduction gear and that holds the magnet in contact with the inner or outer peripheral surface of the magnet;
A magnetic sensor that faces the magnet and detects a rotational position of the output shaft from a change in magnetic pole of the magnet;
Electric motor with speed reduction mechanism, wherein by thermal deformation that fixing the magnet to the reduction gear to the front end of the front Symbol retaining wall the magnet side.

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