Motor with reduction mechanism

Abstract

To provide a motor with a deceleration mechanism capable of suppressing disengagement of gears even when large external force is applied to an output shaft.SOLUTION: A first backup protrusion 21d maintaining engagement between a pinion gear 61 and a helical gear 62 by suppressing inclination of the helical gear 62 is provided in a gear case 20, and a fine gap δS1 is provided between the helical gear 62 and the first backup protrusion 21d. Thus, even when large external force is applied to an output shaft, inclination of the helical gear 62 with respect to the output shaft is suppressed and disengagement of the gears (the pinion gear 61 and the helical gear 62) can be suppressed. When the helical gear 62 is not inclined, smooth rotation of the helical gear 62 with respect to the gear case 20 can be ensured by the fine gap δS1 between the helical gear 62 and the first backup protrusion 21d.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a motor with a speed reduction mechanism, which includes a motor section having a rotating shaft and a speed reduction mechanism section that reduces the rotation speed of the rotating shaft. [Background technology]

[0002] Conventionally, motors with speed reduction mechanisms that are small but capable of producing large output have been used as drive sources for wiper devices, power window devices, etc., that are installed in vehicles such as automobiles. Such on-board motors with speed reduction mechanisms are described, for example, in Patent Document 1.

[0003] The motor with a speed reduction mechanism described in Patent Document 1 includes a brushless motor with a pinion gear and a helical gear with an output shaft that reduces the rotation of the pinion gear and outputs it. The pinion gear and the helical gear form a speed reduction mechanism and are meshed with each other. The axis of the pinion gear and the axis of the output shaft are parallel to each other. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-018035 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the technology described in Patent Document 1, a relatively large space is formed inside the gear case on the opposite side of the pinion gear from the helical gear side. This space is necessary for assembling the first ball bearing, which rotatably supports the pinion gear, in a predetermined position inside the gear case.

[0006] For example, if a large external force is applied to the output shaft, the helical gear, which has helical teeth, tends to tilt relative to the output shaft inside the gear case. As a result, because there is space on the opposite side of the pinion gear from the helical gear side, a large load is applied from the helical gear to the pinion gear, causing the pinion gear to bend away from the helical gear, which could result in the two gears becoming disengaged.

[0007] An object of the present invention is to provide a motor with a reduction mechanism that can prevent gears from coming out of mesh even when a large external force is applied to the output shaft. [Means for solving the problem]

[0008] In one aspect of the present invention, a motor with a reduction mechanism includes a motor section having a rotating shaft and a reduction mechanism section that reduces the rotation speed of the rotating shaft, and includes a first gear that is provided on the rotating shaft so as to be rotatable integrally with the rotating shaft, an output shaft that is provided parallel to the rotating shaft, a second gear that is fixed to the base end side of the output shaft, meshes with the first gear, and rotates at a slower speed than the first gear, a sensor magnet that is fixed to the rotation center of the second gear, a sensor that faces the sensor magnet, and a gearbox that rotatably accommodates the first gear and the second gear. The container has a bottom wall and a side wall integrally formed around the bottom wall. a gear case for rotating the first gear, a first bearing provided in the gear case and rotatably supporting one side of the first gear in the longitudinal direction; a meshing holding portion provided in the gear case and holding the meshing between the first gear and the second gear by preventing the second gear from tilting; a first gap provided between the second gear and the meshing holding portion; a cover member attached to the gear case; a bearing holder disposed between the gear case and the cover member; a second bearing provided in the bearing holder and rotatably supporting the other side of the first gear in the longitudinal direction; a bearing holder side meshing holding portion provided in the bearing holder and holding the meshing between the first gear and the second gear by preventing the second gear from tilting; and a second gap provided between the second gear and the bearing holder side meshing holding portion. a meshing retaining member that retains meshing of the first gear with the second gear is provided on the gear case on the side opposite to the second gear side of the first gear, the meshing retaining member including a fixed main body portion fixed to the gear case and a female thread portion arranged on the side opposite to the first gear side of the fixed main body portion, the side wall portion of the gear case is provided with a meshing retaining member accommodating portion to which the fixed main body portion is fixed, the meshing retaining member accommodating portion is provided with a single screw hole, a fixing screw for fixing the fixed main body portion to the meshing retaining member accommodating portion is inserted into the screw hole, and the fixing screw is fastened to the female thread portion. do. [Effects of the Invention]

[0009] According to the present invention, a meshing retaining portion that prevents the second gear from tilting and maintains meshing between the first gear and the second gear is provided on the gear case, and a gap is provided between the second gear and the meshing retaining portion. This prevents the second gear from tilting relative to the output shaft and prevents the gears from disengaging from each other, even when a large external force is applied to the output shaft. When the second gear is not tilted, the gap between the second gear and the meshing retaining portion ensures smooth rotation of the second gear relative to the gear case. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a cross-sectional view illustrating the internal structure of a motor with a reduction mechanism. [Figure 2] FIG. 2 is a perspective view showing the inside of the gear case. [Figure 3] FIG. 2 is a perspective view showing the helical gear side of the bearing holder. [Figure 4] 2 is an enlarged view of a portion A circled by a dashed line in FIG. 1, illustrating a gap between components. [Figure 5] FIG. 2 is an exploded perspective view showing a bearing holder, a helical gear, and a gear case. [Figure 6] FIG. 2 is a perspective view showing an output shaft, a helical gear, a pinion gear, a rotor, and a backup member. [Figure 7] FIG. 2 is a perspective view showing a pair of surrounding wall portions of the backup member. [Figure 8] FIG. 10 is a perspective view showing the main body fixing portion side of the backup member. [Figure 9] 2 is a cross-sectional view taken along line BB in FIG. 1, showing the gear case and the backup member. [Figure 10] 2 is an enlarged view of a portion A circled by a broken line in FIG. 1, illustrating the state of movement of grease. [Figure 11] 1, illustrating the positional relationship between a helical gear and a backup member. FIG. [Figure 12] FIG. 10 is a perspective view illustrating a second embodiment (bearing holder). [Figure 13]FIG. 10 is a perspective view illustrating a third embodiment (back-up member). DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, the first embodiment of the present invention will be described in detail with reference to the drawings.

[0012] FIG. 1 is a cross-sectional view illustrating the internal structure of the motor with a reduction gear mechanism, FIG. 2 is an oblique view showing the inside of the gear case, FIG. 3 is an oblique view showing the helical gear side of the bearing holder, FIG. 4 is an enlarged view of the dashed circle A in FIG. 1 illustrating the gap between the parts, FIG. 5 is an exploded oblique view showing the bearing holder, helical gear, and gear case, FIG. 6 is an oblique view showing the output shaft, helical gear, pinion gear, rotor, and backup member, FIG. 7 is an oblique view showing the pair of surrounding wall portions of the backup member, FIG. 8 is an oblique view showing the main body fixing portion side of the backup member, FIG. 9 is a cross-sectional view taken along line BB in FIG. 1 showing the gear case and backup member, FIG. 10 is an enlarged view of the dashed circle A in FIG. 1 illustrating the movement of grease, and FIG. 11 is a view seen from the arrow C in FIG. 1 illustrating the positional relationship between the helical gear and backup member.

[0013] [Outline of motor with reduction mechanism] 1 is used, for example, as a drive source for a wiper device mounted on a vehicle such as an automobile. Specifically, the speed reduction motor 10 is disposed in front of the windshield (not shown) of the vehicle and swings a wiper member (not shown) swingably mounted on the windshield within a predetermined wiping range between a lower reversing position and an upper reversing position.

[0014] The motor with speed reduction mechanism 10 has a housing 11 that forms the outer shell of the motor. A brushless motor 50 and a speed reduction mechanism 60 are rotatably housed inside the housing 11. The brushless motor 50 corresponds to the motor section in the present invention, and the speed reduction mechanism 60 corresponds to the speed reduction mechanism section in the present invention.

[0015] The housing 11 also accommodates a first sensor board 12 and a second sensor board 13 used to detect the rotational states of the rotor 52 and the helical gear 62. The housing 11 also includes an aluminum die-cast gear case 20 and a cover member 30 made by pressing a steel plate.

[0016] [Gear case] 1 and 2, the gear case 20 is formed into a generally bowl-shaped shape by injection molding molten aluminum material. Specifically, the gear case 20 includes a bottom wall portion 21, a side wall portion 22 integrally formed around the bottom wall portion 21, and a bearing holder mounting portion 23 to which a bearing holder 40 (see FIG. 3) is mounted.

[0017] A cylindrical boss portion 21a that rotatably supports the output shaft 63 is provided in the approximate center of the bottom wall portion 21. A plurality of reinforcing ribs 21b formed in a roughly triangular shape are provided on the radially outer side of the boss portion 21a. These reinforcing ribs 21b increase the fixing strength of the boss portion 21a to the bottom wall portion 21, and are arranged at equal intervals around the circumferential direction of the boss portion 21a, for example, eight of them.

[0018] A cylindrical bearing member 14, commonly known as a "metal," is attached to the radially inner side of the boss portion 21a. This allows the output shaft 63 to rotate smoothly without rattle relative to the boss portion 21a. An O-ring 15 made of an elastic material such as rubber is attached to the tip side (upper side in Figure 1) and radially inner side of the boss portion 21a. This prevents rainwater, dust, etc. from entering between the output shaft 63 and the bearing member 14.

[0019] Here, a retaining ring 16 is fixed to the center of the output shaft 63 in the longitudinal direction. The retaining ring 16 is hooked onto the tip of the boss portion 21a. As a result, the boss portion 21a is sandwiched between the helical gear 62 and the retaining ring 16, and the output shaft 63 is prevented from coming off the boss portion 21a. Therefore, rattle of the output shaft 63 relative to the boss portion 21a is suppressed, and the quietness of the reduction gear motor 10 is ensured.

[0020] A bearing member accommodating portion 21c is provided at a position eccentric from the boss portion 21a of the bottom wall portion 21. The bearing member accommodating portion 21c is formed in a cylindrical shape with a bottom, and protrudes from the bottom wall portion 21 toward the outside of the gear case 20 (upper side in FIG. 1). A first ball bearing BR1 is accommodated inside the bearing member accommodating portion 21c, and rotatably supports one longitudinal side (tip end side) of the pinion gear 61. Here, the first ball bearing BR1 corresponds to the first bearing in the present invention.

[0021] In this way, the boss portion 21a that supports the output shaft 63 and the first ball bearing BR1 that supports the pinion gear 61 (rotating shaft 53) are each provided in the precisely formed aluminum gear case 20. This allows the output shaft 63 and the rotating shaft 53 to be positioned with high precision, and allows the pinion gear 61 and the helical gear 62 to mesh with high precision inside the gear case 20. This further improves the quietness of the reduction gear motor 10.

[0022] A backup member accommodating portion 22a is provided in a portion of the side wall portion 22 near the bearing holder mounting portion 23. The backup member accommodating portion 22a is arranged in the vicinity of the bearing member accommodating portion 21c. A backup member 70 is accommodated inside the backup member accommodating portion 22a. The backup member 70 is supported by the backup member accommodating portion 22a and is provided so as to cover the periphery of the pinion gear 61. The backup member 70 has the function of preventing the pinion gear 61 from bending when a large external force is applied to the output shaft 63.

[0023] A single threaded hole 22b is formed in the backup member accommodating portion 22a. The threaded hole 22b opens in the radial direction of the pinion gear 61 and the helical gear 62 (the left-right direction in FIG. 1). A fixing screw SC1 for fixing the backup member 70 to the backup member accommodating portion 22a is inserted into the threaded hole 22b. This allows the backup member 70 to be fixed inside the backup member accommodating portion 22a without rattle. This also ensures quietness of the reduction gear motor 10.

[0024] 2 and 9, a pair of case-side inclined surfaces 22c are provided inside the backup member accommodating portion 22a. These case-side inclined surfaces 22c face each other in a direction intersecting the axial direction of the pinion gear 61 and the helical gear 62 (see FIG. 1). The pair of case-side inclined surfaces 22c are located on the leading end side in the insertion direction of the backup member 70 (see FIGS. 7 and 8) into the backup member accommodating portion 22a. In other words, the pair of case-side inclined surfaces 22c are located in a portion of the gear case 20 near the bottom wall portion 21.

[0025] The pair of case-side inclined surfaces 22c are abutted against a pair of backup-member-side inclined surfaces 71b (see FIGS. 7 to 9) provided on the backup member 70. As a result, as shown by arrow M1 in FIG. 9, when the backup member 70 is attached to the backup-member-accommodating portion 22a, the pair of backup-member-side inclined surfaces 71b abut against the pair of case-side inclined surfaces 22c, and the backup member 70 is positioned (centered) at a specified position in the backup-member-accommodating portion 22a.

[0026] That is, the pair of case-side inclined surfaces 22c and the pair of backup-member-side inclined surfaces 71b function to position the backup member 70 in the correct position relative to the backup-member housing portion 22a, thereby facilitating the subsequent tightening operation of the fixing screw SC1 (see arrow M2 in FIG. 9).

[0027] As shown in FIGS. 1 and 2, a first backup protrusion 21d formed in a substantially annular shape is provided on the inside of the bottom wall 21, i.e., on the side of the bottom wall 21 opposite the reinforcing rib 21b. The first backup protrusion 21d has a substantially semicircular cross section and protrudes a predetermined height toward the inside of the gear case 20 (the lower side in FIG. 1). The first backup protrusion 21d has the function of suppressing tilting of the helical gear 62 when a large external force is applied to the output shaft 63. Specifically, the first backup protrusion 21d suppresses tilting of the helical gear 62 inside the gear case 20, thereby maintaining meshing between the pinion gear 61 and the helical gear 62. The first backup protrusion 21d corresponds to the meshing retention portion in the present invention.

[0028] 2, bearing holder mounting portion 23 is provided with bearing holder positioning recess 23a. Bearing holder positioning recess 23a is provided so as to surround the periphery of backup member accommodating portion 22a and is recessed toward backup member accommodating portion 22a. Positioning protrusion 41a (see FIG. 3) provided on bearing holder 40 is fitted into bearing holder positioning recess 23a. Here, bearing holder positioning recess 23a positions bearing holder 40 relative to gear case 20 and corresponds to the positioning portion in the present invention.

[0029] This makes it possible to mount bearing holder 40 with high precision in the correct position relative to bearing holder mounting portion 23. This therefore makes it easy to subsequently fix bearing holder 40 to bearing holder mounting portion 23 using fastening screw SC2 (see FIG. 1), and also makes it possible to precisely position second ball bearing BR2 held in bearing holder 40 and first ball bearing BR1 housed in bearing member housing portion 21c coaxially. This reduces variations in rotational resistance of pinion gear 61 between products.

[0030] [Bearing holder] 1 and 3, bearing holder 40 mounted on bearing holder mounting portion 23 includes first sensor board 12 and a second ball bearing BR2 that rotatably supports the other longitudinal side (base end side) of pinion gear 61. Bearing holder 40 is made up of a holder main body 41 and a sub-holder 42, which are formed by butting together. The second ball bearing BR2 is disposed between holder main body 41 and sub-holder 42. The second ball bearing BR2 corresponds to the second bearing in this invention.

[0031] In this way, by rotatably supporting both longitudinal sides of the pinion gear 61 by the first ball bearing BR1 and the second ball bearing BR2, the pinion gear 61 can rotate smoothly while suppressing curvature (warping) of the pinion gear 61.

[0032] The holder body 41 and the sub-holder 42 are both made of die-cast aluminum and are firmly attached to the gear case 20 (bearing holder attachment portion 23) without any rattle. Also, Fig. 3 shows only the holder body 41 that forms the bearing holder 40.

[0033] As shown in Fig. 3, the holder main body 41 is provided on the helical gear 62 side with a positioning protrusion 41a that fits into the bearing holder positioning recess 23a (see Fig. 2) and is formed in a generally C shape, and a pair of second backup protrusions 41b that are formed in a generally arc shape. The positioning protrusion 41a protrudes higher than the pair of second backup protrusions 41b. Here, the positioning protrusion 41a corresponds to the positioning portion in this invention, and the pair of second backup protrusions 41b correspond to the bearing holder-side meshing and retaining portion in this invention.

[0034] When the bearing holder 40 (holder main body 41) is attached to the gear case 20 (bearing holder attachment portion 23), the pair of second backup protrusions 41b face the first backup protrusions 21d provided on the gear case 20 in the axial direction of the output shaft 63 (see FIG. 1). That is, the pair of second backup protrusions 41b also have the function of preventing the helical gear 62 from tilting when a large external force is applied to the output shaft 63, and maintains the meshing between the pinion gear 61 and the helical gear 62. The pair of second backup protrusions 41b also have a substantially semicircular cross section.

[0035] In this way, the first backup protrusion 21d and the second backup protrusion 41b can support the helical gear 62 from both axial sides, thereby making it possible to more effectively prevent the helical gear 62 from tilting beyond a predetermined angle inside the gear case 20, and more reliably maintaining the meshing between the pinion gear 61 and the helical gear 62.

[0036] Additionally, a total of three screw holes 41c are provided on the outer peripheral edge of the holder main body 41. As shown in Fig. 1, fastening screws SC2 for fixing the cover member 30 and the bearing holder 40 to the gear case 20 are inserted into these screw holes 41c. However, only one fastening screw SC2 is shown in Fig. 1.

[0037] Furthermore, an insertion hole 41d through which the pinion gear 61 is inserted in a non-contact state is provided in the approximate center of the holder body 41. The length dimension of the pair of second backup protrusions 41b is arbitrary, and is not limited to the short length dimension indicated by the solid line in Fig. 3, but can also be set to a long length dimension as indicated by the dashed arrow in the same figure.

[0038] [Cover material] 1, the cover member 30 forming the housing 11 includes a board holding portion 31 formed in a substantially flat plate shape and a motor accommodating portion 32 formed in a substantially cylindrical shape with a bottom. When the cover member 30 is attached to the gear case 20, the board holding portion 31 faces the helical gear 62 in the axial direction of the output shaft 63. The second sensor board 13 is fixed to the inside of the board holding portion 31 via a base member BS.

[0039] Furthermore, an insertion hole 31a is formed in the board holding portion 31, through which a connector connection portion CC, to which an external connector CN on the vehicle side is connected, is inserted. Here, the connector connection portion CC is fixed to the base member BS via a conductive member (not shown), and is electrically connected to the first sensor board 12, the second sensor board 13, and the brushless motor 50. This allows an on-board controller (not shown) connected to the external connector CN to accurately drive the brushless motor 50 in response to detection signals from the first and second sensor boards 12, 13.

[0040] Here, three Hall sensors 12a (only one is shown in the figure) are mounted on the first sensor board 12, and these Hall sensors 12a correspond to the U phase, V phase, and W phase, respectively. The three Hall sensors 12a face permanent magnets MG provided on the rotor 52 in the axial direction of the pinion gear 61. The on-board controller determines the rotational state (rotational speed, rotational direction, etc.) of the brushless motor 50 (pinion gear 61) from the detection signals of the three Hall sensors 12a, and accurately controls the rotational state of the brushless motor 50 based on this.

[0041] On the other hand, a single MR sensor 13a is mounted on the second sensor board 13, and the MR sensor 13a faces a sensor magnet SM fixed to the rotation center of the helical gear 62 in the axial direction of the output shaft 63. The on-board controller then determines the rotation state (rotation position, etc.) of the output shaft 63 from the detection signal of the MR sensor 13a, and based on this, accurately controls the wiping position of the wiper member (not shown) relative to the windshield (not shown).

[0042] When the cover member 30 is attached to the gear case 20, the motor accommodating portion 32 protrudes toward the side opposite the gear case 20 (the lower side in FIG. 1). When the cover member 30 is attached to the gear case 20, the motor accommodating portion 32 faces the bearing member accommodating portion 21c of the gear case 20. A brushless motor 50 is accommodated inside the motor accommodating portion 32.

[0043] Furthermore, a shaft hole 32a is provided in the approximate center of the motor accommodating section 32, and a bearing member BR is provided in the portion of the shaft hole 32a. The bearing member BR rotatably supports the base end side (the lower side in FIG. 1) of the rotating shaft 53 of the brushless motor 50 in the longitudinal direction. In this manner, the rotating shaft 53 including the pinion gear 61 is rotatably supported by a total of three bearings (first and second ball bearings BR1 and BR2 and the bearing member BR).

[0044] [Brushless motor] The brushless motor 50 housed in the motor housing portion 32 includes a stator core 51 formed in a generally cylindrical shape. The stator core 51 is firmly fixed inside the motor housing portion 32 to the sub-holder 42 of the bearing holder 40 in a rotation-preventing state (not shown in detail).

[0045] Stator core 51 is formed by laminating multiple thin steel plates (magnetic material), and multiple teeth (not shown) are radially arranged on the outer periphery of stator core 51. Coils 51a corresponding to U-phase, V-phase, and W-phase are wound around these teeth with a predetermined number of turns using concentrated winding.

[0046] Then, by supplying drive current alternately to U-phase, V-phase, and W-phase coils 51a at a predetermined timing by the on-board controller, rotor 52 provided radially outside stator core 51 is rotated in a predetermined rotational direction with a predetermined drive torque. In other words, brushless motor 50 according to this embodiment is an outer rotor type brushless motor.

[0047] A rotor 52 is rotatably mounted on the radially outer side of the stator core 51 via a small gap (air gap). As shown in Figs. 1 and 6, the rotor 52 rotates a rotating shaft 53 integrally provided with a pinion gear 61, and includes a rotor body 54 formed by pressing a steel plate (magnetic material) to have a generally U-shaped cross section. A plurality of permanent magnets MG formed in a generally tile-like shape are fixed to the radially inner side of the rotor body 54. The rotating shaft 53 integrally provided with the pinion gear 61 is firmly fixed to the center of rotation of the rotor body 54 by press fitting or the like.

[0048] [Deceleration mechanism] As shown in FIGS. 1 and 6 , the reduction gear mechanism 60 rotatably accommodated inside the housing 11 (gear case 20) includes a pinion gear (first gear) 61 integrally provided on the rotating shaft 53, and a helical gear (second gear) 62 that meshes with the pinion gear 61 and rotates at a slower speed than the pinion gear 61. The axes of the pinion gear 61 and the helical gear 62 are parallel to each other. In other words, the rotating shaft 53 and the output shaft 63 are parallel to each other. This allows the reduction gear mechanism 60 to be more compact than a worm reducer that includes a worm and a worm wheel whose axes intersect.

[0049] Furthermore, the pinion gear 61 is disposed on the rotary shaft 53 side (inlet side) of the reduction gear motor 10, and the helical gear 62 is disposed on the output shaft 63 side (outlet side) of the reduction gear motor 10. In other words, the reduction mechanism 60 reduces the high-speed rotation of the pinion gear 61, which has a small number of teeth, to the low-speed rotation of the helical gear 62, which has a large number of teeth. Therefore, the helical gear 62 rotates at a slower speed than the pinion gear 61.

[0050] The rotating shaft 53 including the pinion gear 61 is made of metal, and the pinion gear 61 has a shape as shown in Figures 1 and 7. Specifically, helical teeth (teeth) 61a are integrally formed on the periphery of the pinion gear 61, and the axial length of the helical teeth 61a is slightly longer than the axial length of the helical gear 62. This ensures that the helical teeth 61a mesh with the helical gear 62.

[0051] The helical tooth 61a extends continuously in a spiral shape in the axial direction of the pinion gear 61, and only one helical tooth 61a is provided on the pinion gear 61. In other words, the number of teeth of the pinion gear 61 is "1." The helical tooth 61a is formed so that its cross section is circular, and is adapted to fit into (mesh with) the meshing recess 62d of the helical gear 62.

[0052] The helical gear 62 that forms the reduction mechanism 60 is made of plastic and has a shape as shown in Figures 1 and 6. Specifically, the helical gear 62 has a gear body 62a formed in a substantially disk shape, and the base end side of the output shaft 63 is firmly fixed to the rotation center of the gear body 62a by press fitting or the like. This causes the output shaft 63 to rotate together with the helical gear 62. In addition, a sensor magnet SM is fixed to the rotation center of the gear body 62a on the side of the second sensor substrate 13 (the lower side in Figure 1).

[0053] A gear forming portion 62b formed in a generally cylindrical shape is provided on the radially outer side of the gear body 62a. A plurality of helical teeth 62c are provided on the gear forming portion 62b and aligned in the circumferential direction. These helical teeth 62c are inclined at a predetermined angle with respect to the axial direction of the pinion gear 61, thereby rotating the helical gear 62 in conjunction with the rotation of the helical teeth 61a. Specifically, meshing recesses 62d are provided between adjacent helical teeth 62c, and the helical teeth 61a fit into and mesh with the meshing recesses 62d. The meshing recesses 62d are also formed to have a circular cross-sectional shape.

[0054] A first surface SF1 and a second surface SF2 are provided on both axial sides of the gear forming portion 62b. As shown in FIGS. 1 and 5, the first surface SF1 is disposed on the bottom wall portion 21 side of the gear case 20, and the second surface SF2 is disposed on the bearing holder 40 side. In addition, in the axial direction of the output shaft 63, the first surface SF1 faces the first backup protrusion 21d, and the second surface SF2 faces the pair of second backup protrusions 41b. This prevents the helical gear 62 from tilting when a large external force is applied to the output shaft 63.

[0055] 4, when no large external force is applied to the output shaft 63, a minute gap (gap) δS1 is formed between the first surface SF1 and the first backup protrusion 21d. On the other hand, when no large external force is applied to the output shaft 63, a minute gap δS2 is formed between the second surface SF2 and the pair of second backup protrusions 41b (δS1 ≒ δS2). As a result, during "normal operation" of the motor with a reduction gear mechanism, when no large external force is applied to the output shaft 63, the helical gear 62 is in a non-contact state with both the gear case 20 and the bearing holder 40, allowing for smooth rotation.

[0056] In contrast, during "overload operation" of the motor with a reduction gear mechanism, in which a large external force is applied to the output shaft 63, the helical gear 62 tends to tilt (inside the gear case 20) relative to the axis of the output shaft 63 due to the inclination of the helical teeth 62c. Then, depending on the direction of rotation of the helical gear 62, the first surface SF1 contacts the first backup protrusion 21d (see the dashed arrow in FIG. 5), and the second surface SF2 contacts the pair of second backup protrusions 41b (see the dashed arrow in FIG. 5). This causes the helical gear 62 to be supported (backed up) by the first and second backup protrusions 21d, 41b, preventing the helical gear 62 from tilting further. This prevents the meshing between the helical gear 62 and the pinion gear 61 from deteriorating, preventing the plastic helical gear 62 from being gouged out and damaged by the metal pinion gear 61.

[0057] Here, the number of helical teeth 62c (meshing recesses 62d) provided on the helical gear 62 is 40. That is, in this embodiment, the reduction ratio of the reduction mechanism 60 made up of the pinion gear 61 and the helical gear 62 is 40.

[0058] [Backup member] 1, 4, and 6 to 8, the backup member 70 housed in the backup member housing portion 22a of the gear case 20 is formed in a substantially rectangular parallelepiped shape by injection molding a resin material such as plastic. The backup member 70 includes a fixed main body portion 71 fixed to the gear case 20, a pair of surrounding wall portions 72 formed integrally with the fixed main body portion 71 and surrounding the periphery of the pinion gear 61 together with the fixed main body portion 71, and an annular wall portion 73 formed integrally with one longitudinal side of the surrounding wall portions 72 (the right side in FIGS. 7 and 8) and having a substantially annular shape. The backup member 70 corresponds to the meshing holding member of the present invention.

[0059] A female thread portion 71a is provided on the fixed main body portion 71. The female thread portion 71a is provided in the center of the backup member 70 in the longitudinal direction of the pinion gear 61. The female thread portion 71a is also arranged on the opposite side (back side) of the fixed main body portion 71 to the pinion gear 61 side. A fixing screw SC1 is fastened to the female thread portion 71a to fix the backup member 70 to the gear case 20.

[0060] Furthermore, a pair of backup-member-side inclined surfaces 71b are provided on one longitudinal side of the fixed main body 71 (the right side in FIGS. 7 and 8). These backup-member-side inclined surfaces 71b are respectively abutted against a pair of case-side inclined surfaces 22c (see FIGS. 2 and 9) provided on the gear case 20. Here, as shown in FIG. 9, with the backup-member-side inclined surfaces 71b abutting against the case-side inclined surfaces 22c, a space SP is formed between the leading end of the backup member 70 in the insertion direction and the bottom of the backup-member accommodating portion 22a. This allows the pair of backup-member-side inclined surfaces 71b to abut against the pair of case-side inclined surfaces 22c without any rattle, improving the positioning accuracy of the backup member 70 relative to the gear case 20.

[0061] 1, 4, 6, and 10, when the backup member 70 is assembled to the gear case 20, the fixed main body portion 71 that forms the backup member 70 is provided on the gear case 20 on the side of the pinion gear 61 opposite the helical gear 62. A minute gap δS3 is formed between the pinion gear 61 and the fixed main body portion 71. Here, the minute gap δS3 has approximately the same gap dimension as the minute gap δS1 between the first surface SF1 and the first backup protrusion 21d and the minute gap δS2 between the second surface SF2 and the pair of second backup protrusions 41b (δS1 ≒ δS2 ≒ δS3).

[0062] As a result, during "normal operation" of the motor with reduction mechanism 10, in which no large external force is applied to the output shaft 63, no load is applied from the helical gear 62 to the pinion gear 61 that would cause the pinion gear 61 to bend, and the pinion gear 61 can rotate smoothly without contacting the backup member 70.

[0063] Furthermore, boss portion 21a that supports output shaft 63 and backup member housing portion 22a that supports backup member 70 are each provided in precisely formed aluminum gear case 20, which enables output shaft 63 and backup member 70 to be positioned with high precision relative to each other. This also makes it possible to close minute gap δS3 between pinion gear 61 and fixed main body portion 71 while allowing pinion gear 61 to rotate smoothly without contacting backup member 70.

[0064] On the other hand, when the reduction gear motor 10 is operating under an overload in which a large external force is applied to the output shaft 63, the helical gear 62 tends to tilt relative to the axis of the output shaft 63 due to the inclination of the helical teeth 62c. This causes a large lateral force to be applied to the pinion gear 61 from the radially outer side. Although the pinion gear 61 is made of metal, the portion where the pinion gear 61 is provided is particularly thin, making it vulnerable to lateral loads. As a result, the pinion gear 61 tends to bend due to the radial pressure exerted by the helical gear 62.

[0065] In this case, the approximate center portion in the longitudinal direction of the pinion gear 61 is pressed by the helical gear 62. Therefore, the approximate center portion in the longitudinal direction of the pinion gear 61 comes into contact with the fixed main body portion 71. Because the approximate center portion in the longitudinal direction of the pinion gear 61 is supported (backed up) by the fixed main body portion 71, further bending of the pinion gear 61 is suppressed, and the meshing state between the pinion gear 61 and the helical gear 62 is maintained.

[0066] As the pinion gear 61 bends, pressure is applied to the approximate center of the fixed main body portion 71 in the longitudinal direction, but this approximate center of the fixed main body portion 71 in the longitudinal direction is the portion that is fixed to the gear case 20 by the fixing screw SC1 and is least likely to rattle. Therefore, even if the pinion gear 61 is repeatedly bent, the backup member 70 can support the pinion gear 61 without rattling relative to the gear case 20. This effectively prevents the backup member 70 from being damaged early.

[0067] Furthermore, the minute gap δS3 between the pinion gear 61 and the fixed main body portion 71 is set to a gap dimension sufficient to prevent the pinion gear 61 from disengaging from the helical gear 62. Furthermore, as shown in FIGS. 4 and 10 , in this embodiment, the fixed main body portion 71 is provided over substantially the entire longitudinal length of the pinion gear 61. However, as described above, it is known that substantially the central portion of the pinion gear 61 in the longitudinal direction is bent when the reduction gear motor 10 is in an "overload operation." Therefore, it is sufficient to position the fixed main body portion 71 of the backup member 70 at least in the longitudinal center of the pinion gear 61. Specifically, the shaded portion surrounded by the two-dot chain line in FIG. 10 can be eliminated. In this case, the weight of the backup member 70 can be reduced, and the thickness of the backup member 70 can be reduced, thereby improving the molding precision of the backup member 70.

[0068] 11, the pair of surrounding wall portions 72 extend from the fixed main body portion 71 toward the helical gear 62, and a minute gap δS4 is formed between the tip ends of these surrounding wall portions 72 and the helical gear 62. These surrounding wall portions 72 are provided on both sides of the backup member 70 in the rotational direction of the helical gear 62. The tip ends of the pair of surrounding wall portions 72 are each provided with an inclined surface 72a that is inclined in the circumferential direction of the helical gear 62, and these inclined surfaces 72a extend in the circumferential direction of the helical gear 62 so as to follow the outer peripheral shape of the helical gear 62. Therefore, the space between the pair of inclined surfaces 72a and the helical gear 62 is narrowed, making it possible to form the minute gap δS4.

[0069] 11, by forming a minute gap δS4 between the pair of surrounding wall portions 72 and the helical gear 62, when the helical gear 62 rotates in one direction, as indicated by the solid X arrow, grease (not shown) applied to the meshing portion between the pinion gear 61 and the helical gear 62 is prevented from leaking out of the surrounding wall portion 72. On the other hand, when the helical gear 62 rotates in the other direction, as indicated by the dashed X arrow, grease applied to the meshing portion between the pinion gear 61 and the helical gear 62 is also prevented from leaking out of the surrounding wall portion 72.

[0070] The minute gap δS4 has substantially the same gap dimensions as the minute gap δS1 between the first surface SF1 and the first backup protrusion 21d, the minute gap δS2 between the second surface SF2 and the pair of second backup protrusions 41b, and the minute gap δS3 between the pinion gear 61 and the fixed main body portion 71 (δS1 ≒ δS2 ≒ δS3 ≒ δS4). Also, one of the pair of surrounding wall portions 72 can be eliminated and provided on at least one side of the backup member 70 in the rotation direction of the helical gear 62. Even in this case, the single surrounding wall portion 72 prevents grease from leaking out of the surrounding wall portion 72.

[0071] 7 and 8, the annular wall portion 73 is provided on one side of the backup member 70 (the right side in FIGS. 7 and 8) in the longitudinal direction of the pinion gear 61, and a pinion gear insertion hole 73a is provided in an approximate center portion of the annular wall portion 73. The pinion gear 61 is rotatably inserted through the pinion gear insertion hole 73a in a non-contact state, and a minute gap δS5 is formed between the pinion gear 61 and the pinion gear insertion hole 73a (see FIG. 8).

[0072] The minute gap δS5 has the same gap dimension as the minute gap δS3 between the pinion gear 61 and the fixed main body portion 71 (δS3=δS5).

[0073] 10, by forming minute gap δS5 between pinion gear 61 and pinion gear insertion hole 73a, grease (not shown), which attempts to move as indicated by the solid arrow, is prevented from leaking beyond annular wall portion 73 and out of annular wall portion 73 (see solid x arrow) when pinion gear 61 rotates in one direction. The grease that has been forced into annular wall portion 73 when pinion gear 61 rotates in one direction is returned toward the longitudinal center of pinion gear 61 as indicated by the dashed circle arrow when pinion gear 61 rotates in the other direction.

[0074] In this embodiment, the speed reduction motor 10 is used as a drive source for a wiper device. Therefore, when a wiper member (not shown) is oscillated, the pinion gear 61 and the helical gear 62 are rotated in forward and reverse directions at a predetermined cycle. Therefore, as shown in FIG. 10 , the pinion gear 61 and the helical gear 62 are repeatedly rotated in one direction (forward rotation) and the other direction (reverse rotation), causing grease to move back and forth in the axial direction of the pinion gear 61 inside the backup member 70. In other words, it is possible to retain grease in the meshing portion between the pinion gear 61 and the helical gear 62 for a long period of time.

[0075] When the backup member 70 is accommodated in the backup member accommodating portion 22a and the pair of backup member-side inclined surfaces 71b are respectively abutted against the pair of case-side inclined surfaces 22c, the annular wall portion 73 fits into the opening of the bearing member accommodating portion 21c provided in the gear case 20 (see FIGS. 1, 4, and 10). This prevents the backup member 70 from rattling inside the gear case 20.

[0076] As described above in detail, according to this embodiment, the gear case 20 is provided with the first backup protrusion 21d that prevents the helical gear 62 from tilting and maintains the meshing between the pinion gear 61 and the helical gear 62, and a minute gap δS1 is provided between the helical gear 62 and the first backup protrusion 21d.

[0077] As a result, even when a large external force is applied to the output shaft 63, the inclination of the helical gear 62 with respect to the output shaft 63 is suppressed, and disengagement of the gears (the pinion gear 61 and the helical gear 62) is suppressed. When the helical gear 62 is not inclined, the minute gap δS1 between the helical gear 62 and the first backup protrusion 21d ensures smooth rotation of the helical gear 62 with respect to the gear case 20.

[0078] Therefore, damage to the pinion gear 61 and the helical gear 62 (reduction mechanism 60) can be prevented for a long period of time, thereby enabling an increase in the lifespan of the reduction mechanism-equipped motor 10. In other words, in this embodiment, the lifespan of the reduction mechanism-equipped motor 10 can be increased, thereby saving the energy required to manufacture the reduction mechanism-equipped motor 10, and ultimately making it possible to achieve Goal 7 (Affordable and clean energy) and Goal 13 (Climate action) of the Sustainable Development Goals (SDGs) established by the United Nations.

[0079] Furthermore, according to this embodiment, the rotating shaft 53 and the output shaft 63 are arranged parallel to each other, the pinion gear 61 has one spiral tooth 61a, and the helical gear 62 has helical teeth 62c with which the one spiral tooth 61a meshes. This makes it possible to obtain a large reduction ratio while making the reduction mechanism 60 compact. Therefore, the reduction mechanism-equipped motor 10 can be made compact, making it easily applicable to small vehicles such as light automobiles.

[0080] Furthermore, according to this embodiment, the gear case 20 is provided with a first ball bearing BR1 that rotatably supports one longitudinal side of the pinion gear 61. That is, the boss portion 21a that supports the output shaft 63 and the first ball bearing BR1 that supports the pinion gear 61 are provided in the precisely formed aluminum gear case 20. This allows the output shaft 63 and the rotating shaft 53 to be positioned with high precision relative to each other, and allows the pinion gear 61 and the helical gear 62 to mesh with each other with high precision inside the gear case 20. This further improves the quietness of the reduction gear motor 10.

[0081] Furthermore, according to this embodiment, bearing holder 40 including second ball bearing BR2 that rotatably supports the other longitudinal side of pinion gear 61 is mounted on gear case 20. As a result, both longitudinal sides of pinion gear 61 are rotatably supported by first ball bearing BR1 and second ball bearing BR2, and pinion gear 61 can rotate smoothly while suppressing curvature (warping) of pinion gear 61.

[0082] Furthermore, according to this embodiment, the bearing holder 40 is provided with a pair of second backup protrusions 41b that prevent the helical gear 62 from tilting and maintain the meshing between the pinion gear 61 and the helical gear 62. This, together with the first backup protrusions 21d, makes it possible to support the helical gear 62 from both axial sides. Therefore, it is possible to further prevent the helical gear 62 from tilting relative to the output shaft 63, and more reliably maintain the meshing between the pinion gear 61 and the helical gear 62.

[0083] Furthermore, according to this embodiment, bearing holder 40 and gear case 20 are provided with positioning protrusions 41a and bearing holder positioning recesses 23a, respectively, which position bearing holder 40 relative to gear case 20. This allows bearing holder 40 to be mounted accurately in the correct position relative to bearing holder mounting portion 23. This makes it easy to subsequently fix bearing holder 40 to bearing holder mounting portion 23 using fastening screws SC2, and allows second ball bearing BR2 held in bearing holder 40 and first ball bearing BR1 housed in bearing member housing portion 21c to be positioned coaxially with high precision. This reduces variation in rotational resistance of pinion gear 61 between products.

[0084] Furthermore, according to this embodiment, a backup member 70 that maintains meshing of the pinion gear 61 with the helical gear 62 is provided on the side of the gear case 20 opposite the helical gear 62 side of the pinion gear 61. This prevents the pinion gear 61 from bending, and even when a large external force is applied to the output shaft 63, it is possible to further prevent the gears (the pinion gear 61 and the helical gear 62) from coming out of mesh with each other.

[0085] [Embodiment 2] Next, a second embodiment of the present invention will be described in detail with reference to the drawings. Note that parts having the same functions as those in the first embodiment will be given the same reference numerals, and detailed description thereof will be omitted.

[0086] FIG. 12 shows a perspective view for explaining the second embodiment (bearing holder).

[0087] As shown in Figure 12, bearing holder 80 of embodiment 2 differs from bearing holder 40 of embodiment 1 (see Figure 3) in that an annular base portion 81 is provided around insertion hole 41d of holder main body 41 on the positioning protrusion 41a side. Another difference is that a pair of second backup protrusions 82 extend so as to connect to annular base portion 81.

[0088] The annular base 81 is the portion that faces the other longitudinal side (the lower side in FIG. 1) of the backup member 70 (enclosure wall 72) when the reduction gear motor 10 is assembled (see FIG. 1). As a result, the annular base 81 also prevents grease from leaking beyond the annular base 81 to the outside, similar to the annular wall 73 of the backup member 70 (see FIGS. 7 and 8). The annular base 81 corresponds to the grease leakage prevention portion in this invention.

[0089] The second embodiment configured as described above can also achieve the same effects as the first embodiment. In addition, in the second embodiment, the bearing holder 80 is provided with the annular base portion 81 that prevents leakage of grease applied between the pinion gear 61 and the helical gear 62, thereby preventing the grease from reaching the brushless motor 50. This prevents leaked grease from adversely affecting the operation of the brushless motor 50. Furthermore, the pair of second backup protrusions 82 extend so as to connect to the annular base portion 81, which further prevents the helical gear 62 from being tilted.

[0090] [Embodiment 3] Next, a third embodiment of the present invention will be described in detail with reference to the drawings. Note that parts having the same functions as those in the first embodiment will be given the same reference numerals, and detailed description thereof will be omitted.

[0091] FIG. 13 shows a perspective view for explaining the third embodiment (backup member).

[0092] 13, the backup member 90 of the third embodiment differs from the backup member 70 of the first embodiment (see FIGS. 7 and 8) in that another annular wall portion 91 is provided on the other side of the backup member 90 in the longitudinal direction of the pinion gear 61 (corresponding to the right side in FIGS. 7 and 8). The other annular wall portion 91 also has a pinion gear insertion hole 73a similar to that of the annular wall portion 73. The other annular wall portion 91 faces the annular wall portion 73 in the longitudinal direction of the pair of surrounding wall portions 72.

[0093] The third embodiment configured as described above can also achieve the same effects as the first embodiment. In addition, in the third embodiment, another annular wall portion 91 is also provided on the other side (brushless motor 50 side) of the backup member 70, so that, similar to the second embodiment, the grease is prevented from reaching the brushless motor 50. This prevents the leaked grease from adversely affecting the operation of the brushless motor 50.

[0094] The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiments, the speed reduction motor 10 is applied to a drive source of a wiper device mounted on a vehicle, but the present invention is not limited to this, and can be applied to other drive sources such as a power window device and a sunroof device.

[0095] Furthermore, in each of the above embodiments, the motor 10 with a speed reducer is provided with a brushless motor 50, but the present invention is not limited to this, and a motor with brushes may be used as the motor portion.

[0096] Furthermore, the material, shape, dimensions, number, installation location, etc. of each component in each of the above embodiments are arbitrary as long as they can achieve the present invention, and are not limited to the above embodiments. [Explanation of symbols]

[0097] 10: motor with reduction mechanism, 11: housing, 12: first sensor board, 12a: hall sensor, 13: second sensor board, 13a: MR sensor, 14: bearing member, 15: O-ring, 16: retaining ring, 20: gear case, 21: bottom wall portion, 21a: boss portion, 21b: reinforcing rib, 21c: bearing member accommodating portion, 21d: first backup convex portion (engagement holding portion), 22: side wall portion, 22a: backup member accommodating portion, 22b: screw hole, 22c: case side inclined surface, 23: bearing holder mounting portion, 23a: Bearing holder positioning recess (positioning portion), 30: cover member, 31: board holding portion, 31a: insertion hole, 32: motor accommodating portion, 32a: shaft hole, 40: bearing holder, 41: holder body, 41a: positioning protrusion (positioning portion), 41b: second backup protrusion (bearing holder side meshing holding portion), 41c: screw hole, 41d: insertion hole, 42: sub-holder, 50: brushless motor (motor portion), 51: stator core, 51a: coil, 52: rotor, 53: rotating shaft, 54: rotor body, 60: Reduction mechanism (reduction mechanism part), 61: pinion gear (first gear), 61a: helical teeth (teeth), 62: helical gear (second gear), 62a: gear body, 62b: gear forming part, 62c: helical teeth, 62d: meshing recess, 63: output shaft, 70: backup member (mesh holding member), 71: fixed main body part, 71a: female thread part, 71b: inclined surface on backup member side, 72: surrounding wall part, 72a: inclined surface, 73: annular wall part, 73a: pinion gear insertion hole, 80: bearing holder, 81: annular base part (grease leakage anti-friction part), 82: second backup protrusion, 90: backup member, 91: other annular wall part, BR: bearing member, BR1: first ball bearing (first bearing), BR2: second ball bearing (second bearing), BS: base member, CC: connector connection part, CN: external connector, MG: permanent magnet, SF1: first surface, SF2: second surface, SM: sensor magnet, SP: space, δS1: minute gap (gap), δS2: minute gap, δS3: minute gap, δS4: minute gap, δS5: minute gap

Claims

1. a motor unit having a rotation shaft; a speed reduction mechanism that reduces the rotation speed of the rotary shaft; A motor with a reduction mechanism, a first gear provided on the rotary shaft so as to be integrally rotatable; an output shaft provided parallel to the rotation shaft; a second gear fixed to a base end side of the output shaft, meshed with the first gear, and rotated at a slower speed than the first gear; a sensor magnet fixed to the rotation center of the second gear; a sensor facing the sensor magnet; a gear case that rotatably houses the first gear and the second gear and has a bottom wall portion and a side wall portion integrally formed around the bottom wall portion; a first bearing provided in the gear case and rotatably supporting one longitudinal side of the first gear; a meshing holding portion provided in the gear case, the meshing holding portion preventing the second gear from tilting and holding the meshing between the first gear and the second gear; a first gap provided between the second gear and the meshing holder; a cover member attached to the gear case; a bearing holder disposed between the gear case and the cover member; a second bearing provided in the bearing holder and rotatably supporting the other longitudinal side of the first gear; a bearing holder side meshing holding portion that is provided on the bearing holder and that prevents the second gear from tilting and holds the meshing between the first gear and the second gear; a second gap provided between the second gear and the bearing holder side meshing holding portion; and an engagement holding member that holds the meshing of the first gear with the second gear is provided on a side of the gear case opposite to the second gear side of the first gear, The meshing holding member is a fixed main body portion fixed to the gear case; a female thread portion disposed on the opposite side of the fixed main body portion from the first gear side; Equipped with The side wall portion of the gear case is provided with a meshing holding member accommodating portion to which the fixed main body portion is fixed, The engagement holding member accommodating portion is provided with a single screw hole, A fixing screw for fixing the fixing main body portion to the engagement holding member accommodating portion is inserted into the screw hole, The fixing screw is fastened to the female thread portion. Motor with reduction mechanism.

2. the first gear is a pinion gear having one tooth; the second gear is a helical gear having helical teeth with which the one tooth meshes; The motor with a reduction mechanism according to claim 1.

3. 3. The motor with a reduction mechanism according to claim 1, The bearing holder and the gear case are each provided with a positioning portion that positions the bearing holder relative to the gear case. Motor with reduction mechanism.

4. 3. The motor with a reduction mechanism according to claim 2, The bearing holder is provided with a grease leakage prevention portion that prevents leakage of grease applied between the pinion gear and the helical gear. Motor with reduction mechanism.

Images