Worm and rotation device

Abstract

To realize noise reduction.SOLUTION: A resin worm formed by injection molding includes a portion having teeth, one end part, and the other end part having an apex. The portion includes a cavity extending in a rotary shaft direction. An outer peripheral side surface of the other end part in a circumferential direction has one or more annular marks.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a worm and a rotating device. [Background technology]

[0002] In motor-equipped gearboxes and other devices equipped with worms, techniques for improving the accuracy of the worm are known, for example, to reduce noise. For example, one technique is known in which the teeth at both ends of the worm have inclined surfaces whose outer diameters become smaller toward the ends. Another known worm has a shaft hole press-fitted onto the motor shaft from its base end, and a positioning abutment at the tip of the shaft hole that has an air hole communicating with the shaft hole, with the bottom of the air hole located closer to the base end of the shaft hole than the tip of the motor shaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-137857 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-265169 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when filling the mold with resin, compressed air inside the mold or gas generated from the filled resin can cause improper filling of the resin or voids, which can reduce the accuracy of the worm.

[0005] One object of the present invention is to improve the accuracy of the worm, and another object of the present invention is to provide a rotating device that can achieve quieter operation. [Means for solving the problem]

[0006] In one embodiment, a resin worm is formed by injection molding and includes a toothed portion, one end, and the other end having a vertex. The portion includes a cavity extending in the direction of the rotation axis, and the outer peripheral surface of the other end has one or more annular marks in the circumferential direction.

[0007] According to one aspect, the accuracy of the worm can be improved, and according to another aspect, the noise generated by the rotating device can be reduced. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a plan view showing an example of a rotation device according to an embodiment. [Figure 2] FIG. 2 is a side view showing an example of a rotation device according to an embodiment. [Figure 3] FIG. 3 is a bottom view illustrating an example of a rotation device according to an embodiment. [Figure 4] FIG. 4 is a perspective view of the rotation device according to the embodiment with the first housing removed. [Figure 5] FIG. 5 is a plan view of the rotation device according to the embodiment with the first housing removed. [Figure 6] FIG. 6 is a perspective view illustrating an example of a first housing in the embodiment. [Figure 7] FIG. 7 is a perspective view illustrating an example of the second housing in the embodiment. [Figure 8] FIG. 8 is a top view showing an example of the positional relationship between the helical gear and the worm in the embodiment. [Figure 9] FIG. 9 is a perspective view showing an example of the positional relationship between the helical gear and the worm in the embodiment. [Figure 10] FIG. 10 is an enlarged cross-sectional view showing an example of a rotation device according to an embodiment. [Figure 11] FIG. 11 is a cross-sectional view showing an example of a worm according to an embodiment. [Figure 12] FIG. 12 is a cross-sectional view illustrating an example of a mold according to an embodiment. [Figure 13] FIG. 13 is a cross-sectional view showing an example of a method for forming a worm in an embodiment. [Figure 14] FIG. 14 is an enlarged cross-sectional view illustrating an example of a method for forming a worm in an embodiment. [Figure 15] FIG. 15 is a perspective view showing an example of the positional relationship between the helical gear and the worm in the first modified example. [Figure 16] FIG. 16 is a cross-sectional view showing an example of a worm in the first modified example. [Figure 17] FIG. 17 is a cross-sectional view illustrating an example of a mold according to the first modified example. [Figure 18] FIG. 18 is a cross-sectional view showing an example of a method for forming a worm in the first modified example. [Figure 19] FIG. 19 is an enlarged cross-sectional view illustrating an example of a method for forming a worm in the first modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of a worm disclosed herein will be described in detail below with reference to the drawings. Note that the dimensional relationships and ratios of elements in the drawings may differ from reality. The dimensional relationships and ratios may also differ between the drawings. To facilitate understanding, the drawings may illustrate a coordinate system in which the X-axis direction corresponds to the direction in which a rotating shaft 31 of a motor 3 (described later) extends, i.e., the longitudinal axis of the worm 10, and the Z-axis direction corresponds to the direction in which an output shaft 51 (described later) extends, which is perpendicular to the rotating shaft 31.

[0010] [Embodiment] Fig. 1 is a plan view showing an example of a rotation device according to an embodiment, Fig. 2 is a side view showing an example of a rotation device according to an embodiment, Fig. 3 is a bottom view showing an example of a rotation device according to an embodiment, Fig. 4 is a perspective view showing an example of a rotation device according to an embodiment with a first housing removed, Fig. 5 is a plan view showing an example of a rotation device according to an embodiment with the first housing removed, Fig. 6 is a perspective view showing an example of a first housing according to an embodiment, and Fig. 7 is a perspective view showing an example of a second housing according to an embodiment.

[0011] The rotating device 1 according to the embodiment can be suitably used as an actuator for use in, for example, an air conditioning system for a vehicle, and can control the rotational movement of a louver for controlling the amount of airflow or the like.

[0012] As shown in Figures 1 to 3, the rotating device 1 includes a motor 3 shown in Figures 4 and 5, a plurality of gears (hereinafter referred to as a gear group) 6 that transmit power from the motor 3, and a sensor 7 that detects the rotation angle of an output gear 5 included in the gear group 6.

[0013] The gear group 6 includes a worm 10 attached to the rotating shaft 31 of the motor 3 (see FIG. 10), a first transmission gear 61, a second transmission gear 62, and an output gear 5. As shown in FIGS. 8 and 9, the first transmission gear 61 is located on the positive side in the Y-axis direction relative to the worm 10. FIG. 8 is a top view showing an example of the positional relationship between the helical gear and the worm in the embodiment. FIG. 9 is a perspective view showing an example of the positional relationship between the helical gear and the worm in the embodiment. The first transmission gear 61 is an example of a gear that meshes with the worm.

[0014] 8 to 10, the worm 10 includes a cylindrical portion 11, one end 16 located on the positive side of the cylindrical portion 11 in the X-axis direction, and the other end 13 located on the negative side of the cylindrical portion 11. FIG. 10 is an enlarged cross-sectional view showing an example of a rotation device according to an embodiment. FIG. 10 shows a cross section taken along line AA in FIG. 2. The negative side in the X-axis direction is an example of one side in the direction of the long axis, and the cylindrical portion 11 is an example of a portion having a gear.

[0015] The worm 10 is made of resin and is formed by, for example, injection molding. In this embodiment, the teeth 12 are formed in a spiral shape on the outer periphery of the cylindrical portion 11, as shown in FIGS.

[0016] Returning to FIG. 4, the rotation of the worm 10 is transmitted to the helical gear 61a of the first transmission gear 61, and is also transmitted to the second transmission gear 62 via a gear 61b that is provided coaxially with the helical gear 61a and has a smaller diameter than the helical gear 61a. The helical gear 61a is, for example, a helical gear that meshes with the teeth 12 of the worm 10. The rotation of the second transmission gear 62 is then transmitted to the output gear 5. The output gear 5 is provided with an output shaft 51 (FIG. 3). The rotation axes of the first transmission gear 61 and the second transmission gear 62 extend in the direction of the output shaft 51 (Z-axis direction) and extend in a direction intersecting the rotation axis direction of the worm 10 (X-axis direction).

[0017] In this way, the rotation of the motor 3 is reduced at a predetermined reduction ratio and output from the output shaft 51 to the outside. The rotation angle of this output gear 5 is then detected by the sensor 7. Information on the rotation angle of the output gear 5 detected by the sensor 7 is transmitted to the outside, for example, via the terminal group 4 shown in FIGS. 4 and 5. Note that the sensor 7 may detect not only the rotation angle of the output gear 5 but also the rotation speed, or may detect both the rotation angle and the rotation speed. Furthermore, in this embodiment, a DC motor having a commutator and brushes is used as the motor 3, but a brushless motor or a stepping motor may also be used. If a brushless motor or a stepping motor is used, the sensor 7 may not be necessary for the rotation device 1.

[0018] 2, the housing 2 includes a first housing 21 and a second housing 22 that face each other in the Z-axis direction. That is, the housing 2 is configured by connecting the first housing 21 (FIG. 6) having an opening 214 and the second housing 22 (FIG. 7) having an opening 226 with the openings 214 and 226 facing each other.

[0019] As shown in FIGS. 2 and 6, the first housing 21 has a first surface 210 that forms the top surface of the housing 2, and a first side wall 211 that is provided on the outer periphery of the first surface 210. An opening 214 is surrounded by the first side wall 211. On the other hand, as shown in FIGS. 3 and 7, the second housing 22 has a second surface 220 that forms the bottom surface of the housing 2, and a second side wall 222 that is provided on the outer periphery of the second surface 220. An opening 226 is surrounded by the second side wall 222. The housing 2 is formed of an elastic or deformable resin material, such as polypropylene, polyethylene terephthalate, ABS, or polycarbonate.

[0020] 6, the first housing 21 has a plurality of engaging portions 212 extending toward the second housing 22, which are integrally formed on the outer periphery of the first side wall portion 211. The engaging portions 212 are provided with recesses (hereinafter referred to as engaging recesses) 215. On the other hand, the second housing 22 has a plurality of protrusions (hereinafter referred to as engaging protrusions) 224 formed integrally on the second side wall portion 222 as engaged portions corresponding to the plurality of engaging portions 212 of the first housing 21, respectively, as shown in FIG. The engaging protrusions 224 engage with the engaging recesses 215 of the engaging portions 212.

[0021] In this way, the housing 2 is formed by butting the first housing 21 and the second housing 22 together (see FIG. 2). That is, by engaging the engaging protrusion 224 of the second housing 22 with the engaging recess 215 of the engaging portion 212 of the first housing 21, the first housing 21 and the second housing 22 are integrated together to form the housing 2 that houses the motor 3, gear group 6, and the like. Note that in FIG. 2, the engaging protrusion 224 of the second housing 22 is hidden by the engaging portion 212 of the first housing 21 and cannot be seen.

[0022] In this embodiment, the engaging portion 212 is provided on the first housing 21 and the engaging protrusion 224 is provided on the second housing 22, but it is also possible to provide the engaging portion 212 on the second housing 22 and the engaging protrusion 224 on the first housing 21.

[0023] 6, the first housing 21 is provided with a plurality of protrusions 91 for positioning, and the second housing 22 is provided with a plurality of holes (hereinafter referred to as fitting holes) 92 corresponding to the plurality of protrusions 91 of the first housing 21, as shown in Fig. 7. When the first housing 21 and the second housing 22 are butted together and joined together, the protrusions 91 fit into the fitting holes 92, respectively.

[0024] 6 and 7, outwardly protruding pieces (hereinafter referred to as connecting pieces) 93 are formed on both ends of one side of each of first housing 21 and second housing 22. Joining pieces 93 are provided with holes (hereinafter referred to as connecting holes) 94 through which fasteners (not shown) are inserted as predetermined fixing members, and joined first housing 21 and second housing 22 are firmly connected via four connecting holes 94 with the predetermined fasteners to form an integrated housing 2.

[0025] In the configuration of the housing 2 described above, in this embodiment, protrusions 28 are provided at corners of the first side wall 211 that forms the outer periphery of the first housing 21, and second through holes 282 are provided at corners of the second housing 22. That is, the first housing 21 has a cylindrical protrusion 28 that protrudes from the first surface 210 and has a first through hole 281 through which a fastener such as a bolt or a screw can be inserted. The second housing 22 is then provided with the second through hole 282 into which the protrusion 28 fits.

[0026] A plurality of protrusions 28 are provided, and a corresponding plurality of second through holes 282 are also provided. The plurality of protrusions 28 are provided at a plurality (four) of corners of the first housing 21, respectively, and the plurality of second through holes 282 are also provided at a plurality (four) of corners of the second housing 22, respectively. In this embodiment, the first surface 210 of the first housing 21 and the second surface 220 of the second housing 22 have a substantially rectangular shape in a plan view, and the protrusions 28 and the second through holes 282 are provided at the four corners, respectively.

[0027] The configuration of the motor 3 will be briefly described. As shown in Figures 4, 5, and 10, the motor 3 in this embodiment includes a rotating shaft 31 and a frame 30 that houses a functional unit. Note that the functional unit here refers to a collection of components necessary for driving the motor 3, excluding the rotating shaft 31, such as a stator and rotor that have magnets, coils, etc. In other words, the motor 3 includes the frame 30, the rotating shaft 31 that connects to the worm 10, and the functional unit.

[0028] 4 and 5, the frame 30 includes a cylindrical body 32 extending in the direction of the rotation axis of the motor 3, and two ends in the direction of the rotation axis (a first end 34 and a second end 35). As shown in Fig. 8, the first end 34 is one end on the worm 10 side, and the second end 35 is the other end on the opposite side from the worm 10.

[0029] 10, the first end 34 of the frame 30 includes a first outer surface 342 on the negative side of the X-axis, and a first bearing portion 341 that rotatably supports the worm 10 side portion of the rotating shaft 31 via a first bearing 349. The worm 10, which has teeth 12 that mesh with the first transmission gear 61, is attached to the portion of the rotating shaft 31 that protrudes from the first end 34.

[0030] 8 and 11 are a front view and a cross-sectional view showing an example of a worm in an embodiment. As shown in Fig. 8, the worm 10 includes a cylindrical portion 11 having an outer peripheral side surface, a portion 16 on the motor 3 side relative to the cylindrical portion 11 (hereinafter referred to as one end), and a portion 13 on the opposite side of the motor 3 relative to the cylindrical portion 11 (hereinafter referred to as the other end).

[0031] The other end 13 includes a crest 13a (13a1 and 13a2) (described later), a plurality of inclined surfaces (outer surfaces) 13b arranged to surround the crest 13a, a plurality of vertical surfaces (outer surfaces) 13c, a plurality of outer peripheral side surfaces (outer surfaces) 13d, an outer peripheral side surface 13e, a vertical surface (outer surface) 13f, and a vertical surface (outer surface) 13g. Of these, the plurality of vertical surfaces 13c are respectively arranged between the plurality of inclined surfaces 13b in the circumferential direction. The plurality of outer peripheral side surfaces 13d extend in the rotational axis direction (sometimes referred to as the axial direction) of the worm 10 and are located between the plurality of inclined surfaces 13b and the plurality of vertical surfaces 13c in the rotational axis direction of the worm 10. In this embodiment, the inclined surfaces 13b are outer surfaces extending in a direction intersecting the rotational axis direction of the worm 10. The vertical surfaces 13c, 13f, and 13g extend in a direction perpendicular to the rotational axis direction of the worm 10. The vertical surfaces 13c, 13f, and 13g are outer surfaces extending in a direction intersecting the rotational axis direction of the worm 10, and may be inclined surfaces extending in a direction oblique to the rotational axis direction of the worm 10.

[0032] Vertical surface 13f is located between outer peripheral side surface 13d and outer peripheral side surface 13e in the axial and radial directions and extends in the circumferential direction. Vertical surface 13f is formed on the radially outer side and is substantially flush with multiple vertical surfaces 13c. Vertical surface 13g is located between top portion 13a and inclined surface 13b in the axial and radial directions and extends in the circumferential direction.

[0033] As shown in Fig. 8, a portion of the worm 10 located between one end 16 and the other end 13 is a cylindrical portion 11. Teeth 12 that mesh with the first transmission gear 61 are formed on the outer peripheral side surface of this cylindrical portion 11, and the teeth 12 form part of the outer surface of the worm 10. As shown in Fig. 11, a cavity 14 that extends in the direction of the rotation axis of the worm 10 is formed in the cylindrical portion 11 of the worm 10. The cavity 14 has one end 14a on the side of one end 16 of the worm 10 and the other end 14b on the side of the other end 13 of the worm 10.

[0034] A recess 16a recessed toward the cavity 14 is formed at one end 16 of the worm 10 in the direction of the rotation axis of the worm 10. Gate marks 18 for injecting resin material are formed on the outer peripheral side surface of one end 16 of the worm 10, as shown in FIG. 8. Furthermore, a plurality of recesses 17 are formed in the circumferential direction on the outer peripheral side surface of one end 16 of the worm 10, as shown in FIG. 11. The recess 16a and the plurality of recesses 17 are connected to each other to form a single space.

[0035] As shown in FIG. 10, the rotating shaft 31 of the motor 3 is mounted in the cavity 14 of the worm 10. In the X-axis direction, the cavity 14 is connected to the recess 16a of the worm 10, and one end 14a of the cavity 14 is open toward the recess 16a. In addition, in the direction of the rotation axis of the worm, the other end 14b of the cavity 14 faces the portion that forms the apex 13a of the other end 13 of the worm 10, as shown in FIG. 11. In other words, the other end 14b of the cavity 14 is closed. In addition, the apex 13a is formed in a portion of the outer circumferential side surface of the other end 13 of the worm 10.

[0036] A plurality of (three or more in this embodiment) recesses 15 having holes 15c connecting to the cavity 14 are formed in the circumferential direction on the outer peripheral side surface of the other end 13 of the worm 10. These recesses 15 have a recessed shape in the rotational axis direction of the worm 10. Furthermore, the plurality of recesses 15 have a recessed shape in the radial direction on the outer peripheral side surface of the other end 13 of the worm 10. Specifically, the recesses 15 have an inner surface 15a extending in the rotational axis direction of the worm 10, a portion of a vertical surface 13c described below, and two inner surfaces 15b on both sides of the inner surface 15a and the vertical surface 13c in the circumferential direction.

[0037] The inner surface 15a is located radially inward of the outer peripheral side surface 13d. The inner surface 15a has holes (hereinafter referred to as communicating holes) 15c formed therein that connect to the cavity 14 in the radial direction. That is, the cavity 14 is formed radially inside the multiple recesses 15, and the space inside the recesses 15 is connected to the cavity 14 via the holes 15c. The two inner surfaces 15b face each other in the circumferential direction.

[0038] The vertical surface 13c has a portion that is radially inside the outer peripheral side surface 13d and a portion that surrounds the outer peripheral side surface 13d in the circumferential direction. The vertical surfaces 13c and 13f form a step on the outer peripheral side surface of the worm 10 and extend in a direction intersecting (perpendicular to) the outer peripheral side surfaces 13d and 13e. The vertical surface 13c also forms the bottom surface of the recess 15 in the direction of the rotation axis of the worm 10. The recess 15 is open toward the other side in the direction of the rotation axis.

[0039] The other end 13 of the worm 10 is formed contiguous with the cylindrical portion 11 on the negative side of the X-axis. In the X-axis direction, an apex 13a as the tip of the other end 13 is formed into a curved surface as shown in Fig. 11. In the direction of the rotation axis of the worm 10, the cross section of the apex 13a is formed into a curved shape (e.g., an arc shape). Specifically, the apex 13a of the other end 13 is formed into a hemispherical shape.

[0040] The outer peripheral side surface of the other end 13 of the worm 10 is rotatably supported by a second housing 22, which is another member, with the circumferential direction as the rotation direction. That is, the outer peripheral side surface of the worm 10 is in contact with the second housing 22 and rotates relative to the second housing 22 with the circumferential direction as the rotation direction. Specifically, the top 13a of the other end 13 of the worm 10 is supported by a wall 25 of the second housing 22. The wall 25 has a recess 25a formed in a position corresponding to the top 13a, for example. In this case, the top 13a serves as a pivot on the side of the other end 13 of the worm 10. The recess 25a of the second housing 22 is an example of a part of a housing.

[0041] Three recesses 15 are formed in the other end 13 of the worm 10. The cavity 14 is located radially inward of the recesses 15. In other words, the recesses 15 are located radially outward of the cavity 14. Note that the number of recesses 15 may be one or more.

[0042] The recesses 15 extend in the X-axis direction. Communication holes (holes) 15c that communicate with the cavity 14 are formed in the inner surface 15a that forms the recesses 15. The communication holes 15c are formed at positions that face the cavity 14 in the radial direction. The recesses 15 are formed at equal intervals in the circumferential direction of the other end 13, i.e., in the rotational direction of the worm 10.

[0043] The other end 13 of the worm 10 has one or more annular marks 19 on the outer peripheral side surface. In this embodiment, the multiple annular marks 19 are formed as protrusions 19a, 19b extending in the circumferential direction on the outer peripheral side surface of the worm 10. Specifically, at the other end 13 of the worm 10, a protrusion 19a is formed on the vertical surface 13g surrounding the top 13a, and a protrusion 19b is formed on the vertical surface 13c surrounding the outer peripheral side surface 13d. These protrusions 19a, 19b protrude from the vertical surface 13c and the vertical surfaces 13f, 13g, respectively, in the direction of the rotation axis of the worm 10.

[0044] The protrusion 19a is located near the boundary between the apex 13a and the inclined surface 13b in the radial direction. The protrusion 19b is located near the boundary between the outer peripheral side surface 13d and the outer peripheral side surface 13e in the radial direction. In the rotational axis direction of the worm 10, a part of the recess 15 and a part of the outer peripheral side surface 13d of the other end 13 are located between the protrusions 19a and 19b. In this embodiment, the protrusions 19a and 19b are formed, for example, in a substantially concentric shape. In the following description, when the protrusions 19c and 19b are not to be distinguished from each other, they may be simply referred to as the protrusion 19.

[0045] The protrusions 19 are formed at positions corresponding to gas vents 89 formed in the pin 80, which will be described later. As shown in FIG. 9, the protrusions 19a are formed on the outer peripheral side surface that is located inside the recesses 15 in the circumferential direction. In the embodiment, the protrusions 19 are formed concentrically and extend in the circumferential direction. The concentrically formed protrusions 19 are marks that are continuously formed in an annular shape, and are an example of an annular mark.

[0046] As indicated by an arrow D1 in FIG. 11, the protrusion 19 is located on the negative X-axis direction side of the cavity 14, that is, on the apex 13a side.

[0047] Next, a method for molding the worm 10 will be described with reference to Figs. 12 to 14. Fig. 12 is a cross-sectional view illustrating an example of a mold in an embodiment. Fig. 13 is a cross-sectional view illustrating an example of a method for molding a worm in an embodiment. Fig. 14 is an enlarged cross-sectional view illustrating an example of a method for molding a worm in an embodiment. Fig. 14 is an enlarged view of a portion indicated by frame F1 in Fig. 13. The worm 10 is formed by injection molding using molds 71, 72, and 73 and pins 74, 75, and 80.

[0048] The mold 71 is formed with holes 71a into which the pins 74 and 80 are inserted, and the mold 72 is formed with a hole 72a into which the pin 75 is inserted. The mold 72 is also formed with a gate portion (not shown) for injecting resin. The mold 73 is formed with a molding surface 73a that forms the outer shape of the teeth 12 of the worm 10.

[0049] The pin 80 inserted into the die 71 has a molding surface 80b that forms the inclined surface 13b at the other end 13 of the worm 10, and a molding surface 80f that forms the vertical surface 13f. The pin 80 also has three protrusions 81 that form recesses 15 with communicating holes 15c at the other end 13 of the worm 10. The number of protrusions 81 corresponds to the number of recesses 15. The protrusions 81 each have a molding surface 81c that forms the vertical surface 13c. The pin 80 also has a hole 80a formed therein through which the pin 74 is inserted.

[0050] Furthermore, multiple gas vents 89a and 89b are formed in the pin 80. In this embodiment, the gas vent 89a is formed radially outward of the gas vent 89b. Note that, hereinafter, when there is no need to distinguish between the gas vents 89a and 89b, they may be simply referred to as gas vents 89.

[0051] As shown in Fig. 12, in the direction of the rotational axis of the worm 10, one opening of the gas vent 89a is located on the molding surface 80g, and the other opening is located at the other end 74x of the pin 74. Also, one opening of the gas vent 89b is located on the molding surface 81c, and the other opening is located at the other end 80x of the pin 80. That is, as shown in Fig. 12, the gas vent 89 is a communicating hole (hole) formed in the inner and outer peripheries of the pin 80 and extending in the longitudinal direction of the worm. Note that, as shown in Fig. 13, the gas vent 89b in this embodiment is located along the outer peripheral side surface 81a of the protrusion 81 in the direction of the rotational axis of the worm 10.

[0052] The pin 74 that is inserted into the pin 80 has a substantially hemispherical forming surface 74a that forms the outer peripheral surface (outer surface) 13a1 of the other end 13 of the worm 10.

[0053] The pin 75 inserted into the die 72 is formed with a protrusion 75 a that protrudes radially outward and forms the recess 16 a of one end 16 of the worm 10 .

[0054] When molding the worm 10, the mold 73 is assembled so that one end portion thereof contacts the mold 72 and the other end portion thereof contacts the mold 71 in the direction of the rotational axis of the worm 10, as shown in Fig. 12. With pins 74 and 80 inserted into the mold 71 and pin 75 inserted into the mold 72, the molds 71 ​​and 72 are moved to a predetermined molding position so that they contact the mold 71 in the direction of the rotational axis of the worm. As a result, a cavity 79, which is a gap for molding the worm 10, is formed by the molds 71, 72, 73 and the pins 74, 75, 80, as shown in Fig. 12.

[0055] The three protrusions 81 come into contact with the pins 75 inserted through the dies 72 and 73. As a result, the tips of the protrusions 81 of the pins 80 are supported by the pins 75 in the direction of the rotation axis of the worm 10. As shown in FIG. 14, the portions where the protrusions 81 of the pins 80 and the pins 75 face each other in the radial direction form communication holes 15c between the cavity 14 and the recessed portion 15 of the worm 10.

[0056] The heated and melted resin is then injected at high pressure into the cavity 79 through the gate of the mold 72, filling the cavity 79 with resin and molding the worm 10, as shown in FIG. 13 . During this process, compressed air in the mold and gas generated from the resin being filled are released to the outside of the mold through the gas vent 89. This prevents imperfect resin filling and the generation of voids. When air and gas are released from the gas vent 89, some of the molten resin also flows toward the gas vent 89. In this case, the protrusion 19 of the worm 10 is formed in a position facing the opening of the gas vent 89 on the cavity 79 side. The pin 80 is supported by the protrusion 81, preventing the tip of the pin 80 from bending even when the resin is injected at high pressure.

[0057] After the resin has cooled, the molds 71, 72, 73 and pins 74, 75, 80 are moved to separate the worm 10 from the molds. In the worm 10 formed in this configuration, the resin that flows out from the vertical surfaces 13c and 13f of the other end 13 toward the gas vent 89 hardens, forming multiple protrusions 19 at positions corresponding to the gas vent 89, as shown in Fig. 14. This configuration improves the fluidity of the resin during injection molding, thereby improving the precision of the worm.

[0058] 11 and 14, the apex 13a has a curved outer peripheral surface 13a1 and a cylindrical outer peripheral side surface (outer surface) 13a2. The protrusion 19a is located radially outward (toward the slope 13b) from the curved outer peripheral surface 13a1 and the cylindrical outer peripheral side surface 13a2. The protrusion 19a is located closer to the cylindrical portion 11 than the curved outer peripheral surface 13a1 in the direction of the rotation axis of the worm 10. Meanwhile, the protrusion 19b is located radially outward (toward the tooth 12) from the apex 13a. In other words, the apex 13a is located radially inward from the protrusion 19b. The protrusion 19b is located closer to the positive X-axis direction, i.e., closer to the cylindrical portion 11, than the apex 13a in the direction of the rotation axis of the worm 10. According to this configuration, the convex portion 19 is located at a different position in the direction of the rotational axis of the worm 10 relative to the contact surface between the top 13a and the recess 25a of the wall 25 of the housing 2, so that the top 13a is rotatably supported by the recess 25a.

[0059] As described above, the worm 10 in this embodiment is a resin worm formed by injection molding. The worm 10 includes a cylindrical portion 11 having teeth 12, one end 16, and the other end 13 having a peak. The cylindrical portion 11 includes a cavity 14 with its major axis as its axis, and one or more annular marks 19 are formed on the outer peripheral side surface of the other end 13 in the circumferential direction. This configuration improves the accuracy of the worm 10. Furthermore, since the rotating device 1 includes the worm 10, the rotating device 1 can be made quieter. [Variation 1]

[0060] Although the configuration of this embodiment has been described above, the embodiment is not limited to this. For example, the annular mark corresponding to the position of the gas vent is not limited to that shown in the embodiment, and may be a discontinuous mark arranged in an annular shape, a mark that is part of a ring, or an arc mark, as shown in Figure 15 and subsequent figures. Figure 15 is a perspective view showing an example of the positional relationship between the helical gear and the worm in the first modified example. Figure 16 is a cross-sectional view showing an example of the worm in the first modified example. In the following modified examples, parts that are the same as those shown in the previously described drawings are given the same reference numerals, and duplicated explanations will be omitted.

[0061] As shown in Figures 15 and 16, in the first modified example, the worm A10 has a protrusion 19c and a protrusion 19d on an inclined surface A13b surrounding the apex 13a at the other end A13 of the worm A10, which protrude toward the other side in the X-axis direction. The protrusions 19c and 19d are formed, for example, in a substantially concentric shape. Note that, hereinafter, when the protrusions 19c and 19b are not to be distinguished from each other, they may be simply referred to as the protrusion A19. In addition, in the first modified example, the protrusions 19a and 19b are not formed on the vertical surfaces A13c, A13f, and A13g.

[0062] The protrusions 19c and 19d are formed at positions corresponding to the gas vents 89c and 89d formed in the pin A80 shown in Figure 17 and subsequent figures. Also, the protrusions 19 are formed inside the recesses 15 in the circumferential direction, as shown in Figure 16 and subsequent figures. In the first modified example, the protrusions A19 are formed concentrically and extend in the circumferential direction.

[0063] As indicated by an arrow D1 in FIG. 11, the protrusion 19 is located on the negative X-axis direction side of the cavity 14, that is, on the apex 13a side.

[0064] Next, a method for molding the worm A10 in the first modified example will be described with reference to Figs. 17 to 19. Fig. 17 is a cross-sectional view illustrating an example of a mold in the first modified example. Fig. 18 is a cross-sectional view illustrating an example of a method for molding the worm in the first modified example. Fig. 19 is an enlarged cross-sectional view illustrating an example of a method for molding the worm in the first modified example. Fig. 19 is an enlarged view of the portion indicated by frame F2 in Fig. 18. The worm A10 in the first modified example is formed by injection molding using molds A71, 72, 73 and pins A74, 75, A80.

[0065] The die A71 is formed with holes A71a into which the pins A74 and A80 are inserted. The pin A80 inserted into the die A71 has a molding surface A80b that forms the inclined surface A13b at the other end 13 of the worm A10. The pin A80 is also formed with a hole A80a into which the pin A74 is inserted.

[0066] The pin A80 is formed with a plurality of gas vents 89c and 89d. In a first modified example, the gas vent 89c is formed radially outward of the gas vent 89d. In the following description, when there is no need to distinguish between the gas vents 89c and 89d, they may be simply referred to as the gas vent A89. In this modified example, the gas vent A89 does not face the molding surfaces A80f and A81c.

[0067] An opening on one side in the longitudinal direction of the gas vent A89 is located on the molding surface A80b, and an opening on the other side is located at the other end A80g of the pin A80. That is, the gas vent A89 is a communicating hole that extends in the longitudinal direction and penetrates the pin A80, as shown in Fig. 17. Note that, as shown in Fig. 17, the gas vent A89 in the first modified example is formed in the longitudinal direction and spaced apart from the outer peripheral side surface A81a of the protrusion A81.

[0068] As shown in Fig. 17, the molds A71, 72, and 73 and the pins A74, 75, and A80 form a cavity A79, which is a gap for molding the worm A10. Furthermore, while the gas vent 89 in the embodiment is formed to extend circumferentially as shown in Fig. 9, the gas vent A89 in the first modified example is formed discontinuously in the circumferential direction as shown in Fig. 15.

[0069] In this configuration as well, the fluidity of the resin during injection molding is improved, thereby improving the accuracy of the worm.

[0070] 16 and 19, the protrusion A19 is formed further in the positive direction of the X axis than the apex 13a, i.e., closer to the tube portion 11. Also, as shown by arrow D3 in Fig. 19, the protrusion A19 is formed further outward in the Y axis direction than the apex 13a, i.e., closer to the teeth 12. Even in this configuration, the protrusion 19 does not prevent the apex 13a from contacting the housing 2.

[0071] [Variation 2] In the embodiment, gas vents 89a and 89b are formed in a generally concentric pattern on the outer and inner sides in the radial direction as shown in Fig. 14, and in the first modified example, gas vents 89c and 89d are formed in a generally concentric pattern on the outer and inner sides in the radial direction as shown in Fig. 19, but the embodiment is not limited to this. For example, only one gas vent 89 may be formed in the radial direction, or three or more may be arranged side by side. In either configuration, the convex portion of the worm is formed in a position facing the gas vent in the longitudinal direction, similar to the convex portion 19 of the worm 10 shown in Fig. 14.

[0072] As shown in FIG. 4, the motor 3 is a so-called "square motor" having a substantially rectangular cross section, but is not limited to this and may have any shape, such as a substantially circular cross section.

[0073] Furthermore, the supporting relationship between the worm 10 and the housing 2 is not limited to that shown in the embodiment and each modified example. For example, the top 13a of the other end 13 of the worm 10 may be supported by a portion other than the recess of the second housing 22, or the outer peripheral side surface 13d of the other end 13 of the worm 10 may be supported by the second housing 22. Also, any portion of the other end 13 may be supported by any portion of the first housing 21 instead of the second housing 22. Furthermore, the housing 2 may be provided with other members for supporting the other end 13.

[0074] 12, the gas vent 89 is, for example, a communication hole formed in the pin 80, but is not limited to this. For example, a gap formed in the boundary between the mold 71 and the pin 80, or in the boundary between the pin 74 and the pin 80, may be configured to act as a gas vent.

[0075] While the present invention has been described above based on the embodiments and modifications, it goes without saying that the present invention is not limited to the embodiments and modifications, and various modifications are possible without departing from the spirit of the present invention. Such modifications without departing from the spirit of the present invention are also included in the technical scope of the present invention, and this will be clear to those skilled in the art from the description of the claims. [Explanation of symbols]

[0076] 1 Rotating device, 2 Housing, 3 Motor, 4 Terminal group, 5 Output gear, 6 Gear group, 7 Sensor, 10, A10 Worm, 11 Cylinder portion, 12 Teeth, 13, A13 Other end, 13a Top, 13a1 Outer peripheral surface, 13b, A13b Slope, 13c, 13f, 13g, A13c, A13f, A13g Vertical surface, 13a2, 13d, 13e Outer peripheral side surface, 14 Cavity, 15 Recess, 15c Communication hole, 16 One end, 17 Recess, 18 Gate mark, 19, A19 Convex portion, 21 First housing, 22 Second housing, 28 Protrusion, 30 Frame, 31 Rotating shaft, 32 Cylinder, 34 First end, 35 Second end, 51 Output shaft, 61 First transmission gear, 61a helical gear, 61b gear, 62 second transmission gear, 71 to 73, A71 mold, 74, 75, 80, A74, A80 pin, 81, A81 protrusion, 89, A89 gas vent, 91 protrusion, 92 fitting hole, 93 joint piece, 94 connecting hole, 210 first surface portion, 211 first side wall portion, 212 engagement portion, 214 opening, 215 engagement recess, 220 second surface portion, 222 second side wall portion, 224 engagement protrusion, 226 opening, 281 first through hole, 282 second through hole, 341 first bearing portion, 342 first outer surface, 349 first bearing

Claims

1. A resin worm formed by injection molding, a portion having teeth, one end, and another end having a tip; Equipped with The portion includes a cavity extending in a direction of a rotation axis, In the circumferential direction, the outer peripheral surface of the other end has one or more annular marks. Warm.

2. The worm according to claim 1 , wherein the annular mark is a protrusion extending in a circumferential direction on an outer circumferential surface of the other end portion.

3. The other end is A plurality of recesses are provided in the radial direction, In the rotation axis direction, a part of the recess or a part of the outer circumferential surface of the other end is located between the plurality of annular marks.

3. A worm according to claim 1 or 2.

4. The top portion is The outer circumferential surface is rotatably supported by another member.

3. A worm according to claim 1 or 2.

5. A gear mechanism comprising the worm according to claim 4 and a gear meshing with the worm, a motor having a rotating shaft disposed in the cavity; a housing that houses the motor, the gear, and the worm; Equipped with A rotating device, wherein the other member is a part of the housing or a member provided on the housing.

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