JP7135406B2 - WORM WHEEL, WORM WHEEL MANUFACTURING METHOD AND MOTOR DEVICE - Google Patents

Description

The present invention relates to a worm wheel, a method for manufacturing a worm wheel, and a motor device provided with the worm wheel.

Patent Literature 1 listed below discloses a resin worm wheel attached to an output shaft of an electric motor. This resin worm wheel has teeth on its outer periphery, and the tooth groove bottoms between the teeth are recessed in the tooth groove length direction. Further, the resin worm wheel is composed of two halves divided at approximately the center in the axial direction. It is joined and integrated on the small diameter side, which is the small diameter side. A center hole is formed through the center position of each half body, and the output shaft is attached to the shaft hole formed by these center holes.

In this resin worm wheel, since the entire tooth groove bottom between the teeth is recessed in the tooth groove length direction, it is possible to ensure a wide contact area between the teeth of the worm wheel and the teeth of the worm. This facilitates ensuring the strength of the teeth of the worm wheel. In addition, since the tooth groove bottom of each half is formed in an arc shape so as to form a half of the concave shape, an undercut portion does not exist in the tooth groove bottom when each half is molded with resin. Gone. As a result, the worm wheel with the entire tooth groove bottom recessed can be obtained at low cost and with high precision.

Japanese Patent Application Laid-Open No. 2002-310267

However, in the resin worm wheel having the above configuration, after the two halves are joined (coupled) together, it is necessary to assemble the output shaft (rotating shaft) into the shaft hole of both halves. When the split body is formed or when the joint is slightly misaligned, the shaft hole becomes misaligned, and there is a risk that the joint portion may be damaged or stress may remain due to the insertion and fixation of the output shaft into the shaft hole. As a result, high component precision and assembly precision are required, resulting in an expensive product.

SUMMARY OF THE INVENTION In consideration of the above facts, it is an object of the present invention to provide an inexpensive worm wheel in which the strength of the tooth portion can be easily ensured, a method for manufacturing the worm wheel, and a motor device having the worm wheel.

In the worm wheel of the first aspect of the present invention, a first molded body having a first half-split tooth portion on the outer peripheral portion and a second molded body having a second half-split tooth portion on the outer peripheral portion are coupled in the axial direction. A tooth portion composed of the first half-split tooth portion and the second half-split tooth portion is provided on the outer peripheral portion, and the tooth bottom portion between the tooth portions becomes more axially centered in the axial direction. It comprises a worm wheel main body recessed in an arcuate shape toward the center, and a rotating shaft fixed as an integrally molded product to the axial center of the first molded body.

According to the worm wheel of the first aspect, the worm wheel main body includes the first molded body having the rotating shaft fixed to the axial center portion, the first half-split tooth portion on the outer peripheral portion, and the second half-split tooth portion on the outer peripheral portion. A second molded body having teeth is axially connected. A tooth portion composed of a first half-split tooth portion and a second half-split tooth portion is provided on the outer peripheral portion of the worm wheel main body. The tooth roots between the teeth are arcuately recessed toward the axial center side of the worm wheel main body toward the center side in the axial direction. As a result, it is possible to secure a large contact area between the teeth of the worm wheel body and the teeth of the worm, thereby facilitating securing the strength of the teeth of the worm wheel body. Moreover, the rotating shaft is fixed to the axial center portion of the first molded body as an integrally molded product with the first molded body. Therefore, it is not necessary to assemble the rotating shaft to the worm wheel body after the worm wheel body is manufactured by joining the first molded body and the second molded body. Therefore, it is possible to prevent the occurrence of problems associated with fixing both the first molded body and the second molded body to the rotating shaft, and to obtain an inexpensive resin worm wheel.

A worm wheel according to a second aspect of the present invention is, in the first aspect, formed with tip recesses recessed in an arc shape concentrically with the tooth bottom portions at the tip end portions of the tooth portions.

According to the worm wheel of the second aspect, the worm wheel main body is provided with an arc-shaped dented recess concentric with the tooth bottom between the teeth at the tip of the teeth of the worm wheel body. As a result, it is possible to ensure a wider contact area between the teeth of the worm wheel body and the teeth of the worm than in the case where the tip recesses are not formed at the tips of the teeth of the worm wheel body. .

A worm wheel according to a third aspect of the present invention is, in the first aspect or the second aspect, wherein the second molded body is formed in an annular shape, and the first molded body is the second molded body It has a fitting part fitted inside.

According to the worm wheel of the third aspect, the first molded body and the second molded body are connected in a state in which the fitting portion of the first molded body is fitted inside the annularly formed second molded body. are axially coupled. With this configuration, the first molded body and the second molded body can be positioned radially outward of the peripheral surface of the output shaft with high precision and can be joined with high strength.

A worm wheel according to a fourth aspect of the present invention is characterized in that, in the third aspect, a protrusion or a recess formed on the outer peripheral surface of the fitting portion and a recess or recess formed on the inner peripheral surface of the second molded body The protrusions are fitted to each other.

According to the worm wheel of the fourth aspect, the fitting portion of the first molded body is fitted inside the annularly formed second molded body. The protrusions or recesses formed on the second molded body are fitted with the recesses or protrusions formed on the inner peripheral surface of the second molded body. Thereby, the relative rotation between the first molded body and the second molded body can be effectively restricted.

A worm wheel according to a fifth aspect of the present invention is any one of the first to fourth aspects, wherein the first molded body and the second molded body are made of different materials.

According to the worm wheel of the fifth aspect, the first molded body and the second molded body, which are joined together to form the worm wheel main body, are made of different materials (for example, materials with different shear strengths). As a result, for example, one of the first molded body and the second molded body can be made of a high-strength material and the other can be made of an inexpensive material.

A worm wheel according to a sixth aspect of the present invention is a worm wheel according to any one of the first to fifth aspects, wherein the rotating shaft has a fixed portion in which unevennesses are arranged in the circumferential direction and formed on the outer peripheral surface. , the fixing portion is embedded in the axial center portion of the first molded body.

According to the worm wheel of the sixth aspect, irregularities are formed in the circumferential direction on the outer peripheral surface of the fixed portion of the rotating shaft, and the fixed portion is embedded in the axial center portion of the first molded body. ing. Thereby, relative rotation of the rotary shaft with respect to the first compact can be effectively restricted.

A worm wheel according to a seventh aspect of the present invention is a worm wheel according to any one of the first to sixth aspects, wherein the first molded body and the second molded body are composed of the first half-split tooth portion and the The second half-split tooth portion is coupled with the worm wheel main body in a state of being displaced in the circumferential direction.

According to the worm wheel of the seventh aspect, the worm wheel main body is composed of the first molded body having the first half-split tooth portion on the outer peripheral portion and the second molded body having the second half-split tooth portion on the outer peripheral portion. , are axially coupled. A tooth portion composed of a first half-split tooth portion and a second half-split tooth portion is provided on the outer peripheral portion of the worm wheel main body. In this tooth portion, the first half-split tooth portion and the second half-split tooth portion are shifted in the circumferential direction of the worm wheel body. Due to this deviation, the backlash of the teeth of the worm wheel body with respect to the teeth of the worm can be reduced (including zero backlash).

A worm wheel manufacturing method according to an eighth aspect of the present invention is the worm wheel manufacturing method according to claim 7, wherein the first molded body and the second molded body are mounted on a jig to which the worm is fixed. a mounting step of mounting and engaging the first half-split tooth portion and the second half-split tooth portion with the tooth portion of the worm; a joining step of joining the first molded body and the second molded body in a state in which they are displaced in a direction and brought into close contact with the teeth of the worm.

According to the worm wheel manufacturing method of the eighth aspect, in the mounting step, the first molded body and the second molded body are mounted on the jig to which the worm is fixed, and the first half-split tooth portion and the second half-split tooth portion are mounted. The toothing meshes with the toothing of the worm. Next, in the connecting step, the first molded body and the second molded body are formed in a state in which the first half-split tooth part and the second half-split tooth part are displaced in the circumferential direction of the worm wheel body and are in close contact with the tooth part of the worm. united with the body. As a result, the backlash of the teeth of the worm wheel body with respect to the teeth of the worm can be reduced (including the case where it is reduced to zero).

A motor device according to a ninth aspect of the present invention comprises a motor, a worm rotated by the motor, and a worm wheel according to any one of the first to seventh aspects meshed with the worm. .

According to the motor device of the ninth aspect, when the worm is rotated by the motor, the worm wheel meshed with the worm is rotated about the rotation axis integrally with the rotation axis. Since this worm wheel is a worm wheel according to any one of the first to seventh aspects, the above-described effects can be obtained.

1 is a perspective view of a motor device according to an embodiment of the invention; FIG. FIG. 2 is a perspective view showing a part of the configuration shown in FIG. 1, broken away; It is a perspective view which shows the worm wheel and worm with which the same motor apparatus is provided. 4 is an enlarged perspective view of a portion of the configuration shown in FIG. 3; FIG. It is a side view which shows some worm wheels. FIG. 4 is a cross-sectional view of the worm wheel taken along line F6-F6 in FIG. 3; FIG. 7 is a sectional view showing an enlarged part of FIG. 6; It is an exploded perspective view of a worm wheel. FIG. 5 is a side view showing a state in which the first half-split tooth portion of the first molded body and the second tooth portion of the second molded body, which are constituent members of the worm wheel body, are displaced in the circumferential direction of the worm wheel body. It is a perspective view for explaining a manufacturing method of a worm wheel. FIG. 7 is a cross-sectional view corresponding to FIG. 6 showing a first modified example of the worm wheel according to the embodiment of the present invention; FIG. 11 is a perspective view showing a second modified example of the worm wheel according to the embodiment of the present invention; FIG. 13 is a cross-sectional view showing a cut surface along line F13-F13 of FIG. 12; FIG. 7 is a cross-sectional view corresponding to FIG. 6 showing a third modification of the worm wheel according to the embodiment of the present invention; FIG. 7 is a cross-sectional view corresponding to FIG. 6 showing a fourth modified example of the worm wheel according to the embodiment of the present invention;

A worm wheel 30, a method for manufacturing the worm wheel 30, and a motor device 10 according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 10. FIG. A worm wheel 30 according to this embodiment is a component of the motor device 10 . This motor device 10 is a wiper motor with a speed reducer, and is a brushless motor here. First, the outline of the overall configuration of the motor device 10 will be described, and then the worm wheel 30, which is the main part of the present embodiment, and its manufacturing method will be described. In addition, in the following description, the motor device 10 is called the "wiper motor 10."

(Overall configuration of wiper motor)
As shown in FIGS. 1 and 2, wiper motor 10 includes motor 12 having motor case 14 , gear case 16 and cover 18 . The wiper motor 10 also includes a speed reduction mechanism 20 housed in the gear case 16 and a control board (not shown) housed in the cover 18 .

The motor case 14 is formed in a cylindrical shape with a bottom, for example, from resin or metal. An opening of the motor case 14 is provided with a flange portion 14A. The gear case 16 is made of metal such as iron or aluminum, and is arranged on the opening side of the motor case 14 . The gear case 16 includes a main body portion 16A having a substantially flat box shape with one side open in a direction perpendicular to the axial direction of the motor case 14, and a connecting portion 16B formed on the motor case 14 side of the main body portion 16A. ing. The connection portion 16B has a tubular shape concentric with the motor case 14 . A flange portion 14A of the motor case 14 is fixed to the connection portion 16B by means such as screwing. The cover 18 is made of resin, for example, and has a substantially flat box shape with an opening on the other side in the direction orthogonal to the axial direction of the motor case 14 . The cover 18 is fixed to the gear case 16 by, for example, claw fitting, and closes the opening of the gear case 16 .

The motor 12 having the motor case 14 is an inner rotor type electric motor, and includes a stator and a rotor (not shown) accommodated in the motor case 14 . The stator includes a cylindrical stator core and U-phase, V-phase, and W-phase (three-phase) coils wound around the stator core. The rotor includes a rotor core formed in a cylindrical shape and permanent magnets fixed to the outer peripheral surface of the rotor core, and is coaxially arranged inside the stator. A cylindrical shaft (rotating shaft) 22 made of metal, for example, is coaxially fixed to the axial center of the rotor core. The shaft 22 is arranged from the inside of the motor case 14 to the inside of the gear case 16 . The shaft 22 is rotatably supported by a pair of bearings 24 and 26 attached to the gear case 16, and rotates integrally with the rotor when the three-phase coils of the stator are excited.

A worm 28 is integrally formed between the pair of bearings 24 and 26 of the shaft 22 by means such as rolling. The worm 28 constitutes a reduction mechanism (gear mechanism) 20 together with a worm wheel 30 provided inside the gear case 16 . The worm wheel 30 is composed of a worm wheel main body 32 having teeth 33 formed on the outer peripheral portion thereof, and an output shaft 44 coaxially fixed to the axial center portion of the worm wheel main body 32. The worm wheel 30 rotates in the axial direction. It is arranged in a posture orthogonal to the axial direction of the shaft 22 . The toothed portion 33 of the worm wheel main body 32 meshes with the toothed portion 29 of the worm 28 (the reference numeral is omitted in FIG. 2). The output shaft 44 corresponds to the "rotating shaft" in the present invention. The output shaft 44 extends to one side in the axial direction of the worm wheel 30 (the side opposite to the cover 18), and is inserted through a cylindrical portion 16C formed in the body portion 16A of the gear case 16. . A pair of bearings (not shown) are mounted in the tubular portion 16C, and the output shaft 44 is rotatably supported by these bearings. The output shaft 44 rotates integrally with the worm wheel 30 when the worm wheel 30 is decelerated and rotated by the rotation of the worm 28 (rotating shaft 22).

A plurality (here, three) of vehicle-body-side fixing portions 16D are formed around the cylindrical portion 16C. Female threaded portions are formed on these vehicle body side fixing portions 16D, and the wiper motor 10 is fixed to the vehicle body via brackets, frames, etc. (not shown) using externally threaded members such as bolts that are screwed into the respective female threaded portions. be done. A wiper arm (not shown), for example, has its base end fixed to the output shaft 44, and a wiper blade is connected to the tip end of the wiper arm. By rotating the wiper arm integrally with the output shaft 44, the wiper blade (not shown) wipes the windshield glass (not shown) of the vehicle.

A plate-shaped grease cover 19 (see FIG. 2) is arranged on the other side of the worm wheel 30 in the axial direction. , a control board (not shown) is arranged. A connector portion 17 is formed in the gear case 16 corresponding to the control board. A terminal (not shown) provided on the connector portion 17 is electrically connected to the control board. An external connector (not shown) provided on the vehicle body side is connected to the connector portion 17 . As a result, the control board is electrically connected to the vehicle-mounted battery and the wiper switch (both of which are not shown). The three-phase coils described above are electrically connected to this control board. The control board also includes three rotation sensors (for example, Hall ICs) that perform switching operations in response to changes in the magnetic poles of a first sensor magnet (not shown) attached to the rotating shaft 22, and a shaft center portion of the worm wheel 30. An MR sensor (for example, a magnetoresistive element) (not shown) that performs a switching operation based on a change in the magnetic pole of a second sensor magnet (not shown) attached to the sensor is mounted.

Furthermore, various electronic parts such as a CPU, a controller chip, a capacitor, an inductor, and an FET module are mounted on this control board to form an electronic circuit. The CPU is composed of a known microcomputer, and the FET module has a plurality of switching elements. The CPU and FET module supply exciting currents to the three-phase coils described above to control the rotation of the rotor. At this time, the CPU controls the FET module based on the detection values detected by the three rotation sensors and the MR sensor. Specifically, the CPU detects the rotational state of the rotor (rotational speed, rotational position, rotational direction, etc.) based on the detection values detected by the three rotation sensors, and detects the detection values detected by the MR sensor. , the rotational position (absolute position) of the output shaft 44 with respect to the gear case 16 is detected. Then, the CPU controls the FET module based on these detection results. As a result, the output shaft 44 is configured to reciprocate integrally with the wiper arm.

(Main part of this embodiment)
Next, the worm wheel 30, which is the main part of this embodiment, and a method of manufacturing the same will be described in detail. The worm wheel 30 is composed of the worm wheel main body 32 and the output shaft 44 as described above. As shown in FIGS. 2 to 8, the worm wheel main body 32 includes a first molded body 36 having a first half-split tooth portion 37 (reference numerals are omitted in FIG. 2) on the outer peripheral portion, and a second half-split tooth portion on the outer peripheral portion. A second molded body 40 having teeth 41 (not shown in FIG. 2) is axially connected. The first molded body 36 and the second molded body 40 are made of different materials. A specific description will be given below.

The first molded body 36 is manufactured here by injection molding of resin (for example, polyacetal), and is formed in a substantially disc shape. Specifically, the first molded body 36 includes a main body portion 36A formed in a disk shape, and a radially outer portion of the main body portion 36A to one axial side of the main body portion 36A (arrows in FIGS. A direction side) and an annular convex portion 36B that protrudes in an annular shape (ring shape), and both sides of the main body portion 36A in the axial direction from the radial center portion of the main body portion 36A (arrow A direction side and arrow B direction side) and a plurality of reinforcing ribs 36D radially extending from the outer peripheral portion of the boss portion 36C. The boss portion 36C and the plurality of reinforcing ribs 36D are arranged inside the annular convex portion 36B, and the boss portion 36C and the annular convex portion 36B are formed coaxially with the main body portion 36A.

A first half-split tooth portion 37 is formed on the outer peripheral portion of the body portion 36A. The first half-split tooth portion 37 is a portion of the tooth portion 33 of the worm wheel main body 32 on one side in the axial direction of the worm wheel main body 32 (half or approximately half on the arrow B direction side in FIGS. 3 to 8). constitutes

The annular convex portion 36B has the same axial dimension as the main body portion 36A. A plurality of (here, eight) recesses 38 are formed in the circumferential direction of the annular protrusion 36B on the outer peripheral surface of the annular protrusion 36B. The plurality of recesses 38 are recessed in an arc shape toward the axial center side of the first molded body 36 when viewed from the axial direction of the first molded body 36, and the radially outer side of the first molded body 36 is open. . This annular convex portion 36B corresponds to the "fitting portion" in the present invention.

The boss portion 36C is formed in a bottomed cylindrical shape with one side of the first molding 36 in the axial direction (arrow A direction side in FIGS. 3 to 8) open. An output shaft 44 is coaxially fixed to the axial center portion of the first molded body 36 inside the boss portion 36C. The output shaft 44 is fixed as an integrally molded product to the first molded body 36 by integral molding (insert molding) with the first molded body 36 . One axial end of the output shaft 44 is a serration portion 44A (see FIG. 6) as a fixed portion, and the serration portion 40A is embedded in the axial center portion of the first molded body 36. As shown in FIG. A plurality of irregularities (grooves and ridges) extending in the axial direction of the output shaft 44 are formed along the outer peripheral surface of the serration portion 44A in the circumferential direction. These irregularities are formed by means such as rolling or cold forging.

Here, the second molded body 40 is manufactured by injection molding of a resin (for example, polyacetal containing glass fiber, or polyacetal with a different amount of glass fiber than that of the first molded body 37). It is formed in a (ring shape). The outer diameter of the second molded body 40 is set equal to the outer diameter of the first molded body 36, and the inner diameter of the second molded body 40 is set equal to the outer diameter of the annular projection 36B, The axial dimension of the second molded body 40 is set equal to the axial dimension of the annular projection 36B.

A second half-split tooth portion 41 is formed on the outer peripheral portion of the second compact 40 . The second half-split tooth portion 41 is a portion of the tooth portion 33 of the worm wheel main body 32 on the other side in the axial direction of the worm wheel main body 32 (half or approximately half on the arrow B direction side in FIGS. 3 to 8). constitutes In addition, a plurality of (here, eight) protrusions 42 are formed on the inner peripheral portion of the second molded body 40 on one axial end side (direction of arrow A in FIGS. 3 to 8). are formed in the same direction. The plurality of protrusions 42 are arcuately protruding toward the axial center side of the second molded body 40 when viewed from the axial direction of the second molded body 40 .

In this embodiment, the worm wheel main body 32 is configured by coupling the first molded body 36 and the second molded body 40 configured as described above in the axial direction. Specifically, the annular projection 36B of the first molded body 36 is fitted inside the second molded body 40, and the plurality of projections 42 of the second molded body 40 are fitted to the plurality of projections of the first molded body 36. It fits in the recess 38 . A plurality of protrusions 42 are joined to the first molded body 36 (mainly main body 36A) by welding. Thus, the first molded body 36 and the second molded body 40 are fitted together at a position sufficiently radially outside the outer peripheral surface of the output shaft 44 .

A tooth portion 33 consisting of a first half-split tooth portion 37 and a second half-split tooth portion 41 is provided on the outer peripheral portion of the worm wheel main body 32 . In this worm wheel body 32, as shown in FIGS. 6 and 7, the tooth bottom portions 35 between the tooth portions 33 move toward the axial center side of the worm wheel body 32 as it goes toward the center side in the axial direction of the worm wheel body 32. It is concave like an arc. Further, in the worm wheel main body 32 , tip recesses 34 are formed at the tip end portions of the tooth portions 33 so as to be concentric with the tooth bottom portions 35 and recessed in an arc shape. The tooth bottom portion 35 and the tip recess portion 34 are formed in an arcuate shape that is concentric or substantially concentric with the worm 28 at the point where the tooth portion 33 of the worm wheel body 32 and the tooth portion 29 of the worm 28 are meshed. .

In the worm wheel 30 configured as described above, the annular convex portion 36B of the first molded body 36 is fitted inside the second molded body 40, and the plurality of convex portions 42 of the second molded body 40 are fitted to the first molded body 36. Before being welded to the worm wheel main body 32 , the plurality of projections 42 are configured to be slightly movable relative to the plurality of recesses 38 in the circumferential direction of the worm wheel body 32 . As a result, in a state in which the first half-split tooth portion 37 and the second half-split tooth portion 41 are slightly displaced in the circumferential direction of the worm wheel main body 32 (see FIG. 9), the first molded body 36 and the second molded body 40 can be welded (bonded).

When manufacturing the worm wheel 30 in which the first half-split tooth portion 37 and the second half-split tooth portion 41 are shifted as described above, the following mounting process and coupling process are performed. In the mounting step, the first molded body 36 and the second molded body 40 are mounted on a jig 50 (see FIG. 10) to which a worm 52 similar to the worm 28 is fixed, and the first half-split tooth portion 37 and the second half-tooth portion are mounted. The split tooth portion 41 meshes with the tooth portion of the worm 52 (not shown in FIG. 10). Next, in the connecting step, the first half-split tooth portion 37 and the second half-split tooth portion 41 are slightly displaced in the circumferential direction of the worm wheel main body 32 and are in close contact with the tooth portion of the worm 52, and the jig is attached. The first molded body 36 and the second molded body 40 are held by the jig 50 by a plurality of positioning members 54 provided on the jig 50 . In this state, the plurality of protrusions 42 of the second compact 40 are welded to the first compact 36 . Although FIG. 10 shows only one trowel 56 for welding the projections 42 to the first molded body 36 , a plurality of trowels 56 are used to simultaneously weld a plurality of projections 42 to the first molded body 36 . It can be welded.

(Action and effect)
Next, the operation and effects of this embodiment will be described.

In the worm wheel 30 of the wiper motor 10 according to the present embodiment, the worm wheel main body 32 includes a first molded body 36 having an output shaft 44 fixed to the axial center portion and a first half-split tooth portion 37 on the outer peripheral portion; A second molded body 40 having a second half-split tooth portion 41 at its portion is coupled in the axial direction. A tooth portion 33 consisting of a first half-split tooth portion 37 and a second half-split tooth portion 41 is provided on the outer peripheral portion of the worm wheel main body 32 . A tooth bottom portion 35 between the tooth portions 33 is recessed in an arc shape toward the axial center side of the worm wheel main body 32 toward the center side in the axial direction. As a result, a large contact area can be secured between the toothed portion 33 of the worm wheel body 32 and the toothed portion 29 of the worm 28, so that the strength of the toothed portion 33 of the worm wheel body 32 can be easily secured.

In particular, wiper motors are used in harsh environments where the wiper arm must withstand external forces such as falling snow. Therefore, it is desired to reduce the size of the worm wheel made of resin or the like, and it is becoming difficult to ensure the strength of the teeth of the worm wheel. In this regard, according to the present embodiment, a large contact area can be secured between the tooth portions 33 of the worm wheel body 32 and the tooth portions 29 of the worm 28 as described above. It is possible to provide a small resin worm wheel 30 with sufficient strength.

Moreover, the output shaft 44 (rotating shaft) of the worm wheel 30 is fixed to the axial center portion of the first molded body 36 as an integrally molded product by integral molding with the first molded body 36 . Therefore, it is not necessary to assemble the output shaft 44 to the worm wheel body 32 after the worm wheel body 32 is manufactured by combining the first molded body 36 and the second molded body 40 . In other words, although the output shaft 44 is fixed to the first molded body 36 as an integrally molded product, it is not directly fixed to the second molded body 40, but is integrally fixed via the first molded body 36. be. Therefore, it is possible to prevent the occurrence of problems caused by fixing both the first molded body 36 and the second molded body 40 to the output shaft 44 as in the prior art, and to obtain an inexpensive resin worm wheel. Also, an increase in the number of assembly man-hours can be suppressed.

Further, in the present embodiment, an arcuate recess 34 concentric with the tooth bottom 35 between the teeth 33 is formed at the tip of the teeth 33 of the worm wheel body 32 . As a result, the contact area between the tooth portions 33 of the worm wheel body 32 and the tooth portions 29 of the worm 28 is increased compared to the case where the tip recesses 34 are not formed in the tip portions of the tooth portions 33 of the worm wheel body 32. can be secured.

Further, in the present embodiment, the first molded body 36 has a disk-shaped body portion 36A and an annular convex portion 36B that annularly protrudes from the body portion 36A to one side in the axial direction. The annular convex portion 36B is fitted inside the second molded body 40 formed in an annular shape. In this manner, the first molded body 36 and the second molded body 40 are fitted together at a position sufficiently radially outward of the outer peripheral surface of the output shaft 44. The second molded body 40 can be positioned with high accuracy in the radial direction and the circumferential direction and can be firmly coupled.

Further, in this embodiment, the plurality of recesses 38 formed on the outer peripheral surface of the annular protrusion 36B of the first molded body 36 and the plurality of protrusions 42 formed on the inner peripheral surface of the second molded body 40 are are interlocked. As a result, the relative rotation between the first molded body 36 and the second molded body 40 can be effectively restricted, and the first molded body 36 and the second molded body 40 can be strongly coupled in the circumferential direction. can.

Furthermore, in this embodiment, the first molded body 36 and the second molded body 40, which are joined together to form the worm wheel body 32, are made of different materials. Specifically, the first molded body 36 is made of resin (polyacetal) having excellent self-lubricating properties, and the second molded body is made of glass fiber-containing resin (polyacetal). As described above, the second molded body 40 is made of a material having higher strength than the material of the first molded body 36, and the first molded body 36 is made of a material that is cheaper than the material of the second molded body 40. , the manufacturing cost can be reduced while ensuring the strength of the tooth portion 33 .

Further, in this embodiment, the output shaft 44 has a serration portion 44A formed on the outer peripheral surface of the output shaft 44 with unevenness arranged in the circumferential direction. Embedded. As a result, relative rotation of the output shaft 44 with respect to the first molded body 36 can be effectively restricted.

Furthermore, in the present embodiment, the first molded body 36 and the second molded body 40 are arranged in a state in which the first half-split tooth portion 37 and the second half-split tooth portion 41 are slightly displaced in the circumferential direction of the worm wheel main body 32 . and can be combined. Due to the above deviation, the backlash of the teeth 33 of the worm wheel main body 32 against the teeth 29 of the worm 28 can be reduced (including the case where it is made zero). In other words, since some molding errors occur when molding the first molded body 36 and the second molded body 40, it is possible to reduce the backlash by only molding the first molded body 36 and the second molded body 40. There is a limit. In this regard, in the present embodiment, the first half-split tooth portion 37 and the second half-split tooth portion 41 are shifted in the circumferential direction of the worm wheel main body 32 when the first compact 36 and the second compact 40 are joined together. Therefore, the above backlash can be effectively reduced or eliminated. In particular, in the wiper motor 10 of the type that reciprocates the output shaft 44 as in the present embodiment, a large load is applied to the tooth portion 33 due to the above backlash, but in the present embodiment, the above load can be effectively reduced. Become.

<various modifications>
Next, various modifications of the above embodiment will be described with reference to FIGS. 11 to 15. FIG. Configurations and actions that are basically the same as those of the above-described embodiment are given the same reference numerals as those of the above-described embodiment, and the description thereof is omitted.

(First modification)
FIG. 11 shows a cross-sectional view corresponding to FIG. 6 of a first modification of the worm wheel 30 according to the embodiment of the invention. In this first modified example, a recess 34' different from the tip recess 34 according to the above-described embodiment is formed at the tip of the tooth portion 33 of the worm wheel body 32. As shown in FIG. The concave portion 34' is recessed in an arc shape concentrically with the tooth bottom portion 35 at the portion formed by the first molded body 36, and has a substantially rectangular shape toward the tooth bottom portion 35 side at the portion formed by the second molded body 40. recessed in Also in this first modification, the second half-split tooth portion 41 has the protruding portion 41A that protrudes radially outward from the second molded body 40, so that the contact area between the tooth portion 33 and the tooth portion 29 is reduced to It can be enlarged by the protrusion 41A.

(Second modification)
FIG. 12 shows a perspective view of a second modification of the worm wheel 30 according to the embodiment of the present invention, and FIG. 13 shows a cross-sectional view taken along line F13-F13 of FIG. is indicated by 12 shows a state before the first molded body 36 and the second molded body 40 are joined (immediately before the first molded body 36 and the second molded body 40 come into contact with each other in the axial direction). 13 shows a state in which the first molded body 36 and the second molded body 40 are in contact with each other in the axial direction.

In this second modification, the first molded body 36 has a boss portion 36E different from the boss portion 36C according to the above embodiment, and has the annular convex portion 36B and the reinforcing rib 36D according to the above embodiment. It is configured not to The boss portion 36E is formed in the center portion in the radial direction of the main body portion 36A in the same manner as the boss portion 36C according to the above-described embodiment, but is located on the other side of the main body portion 36A in the axial direction (arrow B direction side in FIG. 13). It stands out only in Further, the second molded body 40 is formed to have a smaller inner diameter than that of the above-described embodiment, and is arranged on the other side in the axial direction with respect to the first molded body 40 . A boss portion 36</b>E is fitted inside the second molded body 40 . That is, in this second modification, the boss portion 36E corresponds to the "fitting portion" in the present invention.

In addition, the second molded body 40 has a thin portion 40A whose axial dimension is reduced compared to the outer peripheral portion at the radially central portion except for the outer peripheral portion. A plurality of welding recesses 60 are formed in the thin portion 40</b>A so as to be aligned in the circumferential direction of the second molded body 40 . The plurality of welding recesses 60 are recessed toward one axial side (arrow A direction side in FIG. 13) of the second molded body 40 . Then, the second molded body 40 and the first molded body 36 are welded (bonded) by a soldering iron 56 (see FIG. 13) abutted against the bottom surfaces of these welding recesses 60 . Note that FIG. 13 shows a state before the bottom surface of the welding recess 60 is melted. Also in this second modified example, basically the same effects as those of the above-described embodiment can be obtained.

(Third modification)
FIG. 14 shows a cross-sectional view corresponding to FIGS. 6 and 13 of a third modification of the worm wheel 30 according to the embodiment of the invention. The third modified example has a configuration similar to the second modified example, but differs from the second modified example in the configuration of the welded portion between the first molded body 36 and the second molded body 40 .

In this third modification, the first molded body 36 includes a plurality of welding projections 70 projecting from the radially intermediate portion of the body portion 36A toward the other axial side of the body portion 36A (arrow B direction side in FIG. 14). have. A plurality of welding projections 70 are formed side by side in the circumferential direction of the first molded body 36 . Further, the thin portion 40A of the second molded body 40 is formed with a plurality of welding holes 72 in which the plurality of welding projections 70 are fitted. The distal end portions of the plurality of welding projections 70 protrude from the plurality of welding holes 72 to the other side in the axial direction. Then, the second molded body 40 and the first molded body 36 are welded (bonded) by the soldering iron 56 abutted against the tip end portions of the welding protrusions 70 . It should be noted that FIG. 14 shows a state before melting of the convex portion 70 for welding. Also in this third modified example, basically the same effects as those of the above-described embodiment can be obtained.

(Fourth modification)
FIG. 15 shows a fourth modification of the worm wheel 30 according to the embodiment of the invention in a cross-sectional view corresponding to FIGS. 6 and 13. As shown in FIG. This third modification has a configuration similar to that of the second modification, but the fitting structure between the first molded body 36 and the second molded body 40 and the structure for fitting the first molded body 36 and the second molded body 40 are different. The configuration of the welded portion is different from that of the second modification.

In this fourth modification, the second molded body 40 is formed with a larger inner diameter than in the second modification. The first molded body 36 also has a projecting portion 36F that annularly projects from the main body portion 36A to the other side in the axial direction (arrow B direction side in FIG. 15) radially outside the boss portion 36E. The projecting portion 36F corresponds to the “fitting portion” in the present invention, and is fitted inside the second molded body 40. As shown in FIG. A welding rib 80 projecting in a ring shape toward the other side in the axial direction is formed from the outer peripheral portion of the protruding portion 36F. The welding rib 80 protrudes from the thin portion 40A of the second molded body 40 toward the other side in the axial direction. The second molded body 40 and the first molded body 36 are welded (bonded) by the soldering iron 56 abutted against the tip portion of the welding rib 80 . It should be noted that FIG. 15 shows a state before the welding rib 80 is melted. Moreover, in this fourth modification, the iron 56 is formed in a cylindrical shape. Also in this fourth modified example, basically the same effects as those of the above-described embodiment can be obtained.

<Supplementary description of the embodiment>
In the above-described embodiment and various modifications, the first molded body 36 and the second molded body 40 are preferably made of resin, but the first molded body 36 and the second molded body 40 are not limited to this. may be made of metal.

In addition, in the above-described embodiment and various modifications, the first molded body 36 and the second molded body 40 are joined by welding, but the present invention is not limited to this, and the first molded body 36 and the second molded body may be combined by adhesion, bolting, or the like.

Further, in the above-described embodiment and various modifications, the fitting portions (annular convex portion 36B, boss portion 36E, projecting portion 36F) provided in the first molded body 36 are formed in an annular shape to form the second molded body 40. Although the configuration is such that it is fitted inside, the present invention is not limited to this. That is, the disc-shaped first molded body and the disc-shaped second molded body may be coupled in the axial direction. In that case, a boss portion extending in the opposite direction to the second molded body is formed in the radially central portion of the first molded body, and the boss portion supports the rotating shaft fixed to the axial center portion of the first molded body. is preferred.

In addition, in the above-described embodiment and various modifications, the first molded body 36 and the second molded body 40 are made of different materials (the resin base material is the same, but glass fibers are added to make different materials). ), but the first molded body and the second molded body may be made of the same material. Further, the resin base material itself may be different between the first molded body 36 and the second molded body 40, and furthermore, one is made of a metal material to increase the strength, and the other is made of a resin material so as to obtain lubricity. Also good.

Further, in the above embodiment and various modifications, the motor device is applied to a brushless motor, but the present invention is not limited to this, and may be a brush motor.
In addition, the present invention can be implemented with various modifications without departing from the scope of the invention. In addition, the scope of rights of the present invention is not limited to the above embodiments and various modifications.

DESCRIPTION OF SYMBOLS 10... Wiper motor (motor apparatus), 12... Motor, 28... Worm, 29... Tooth part, 30... Worm wheel, 32... Worm wheel main body, 33... Tooth part , 34... Tip concave part, 35... Tooth bottom part, 36... First molding, 36B... Annular convex part (fitting part), 36E... Boss part (fitting part), 36F ... Protruding portion (fitting portion), 37 ... First half-split tooth portion, 38 ... Recessed portion, 40 ... Second molded body, 41 ... Second half-split tooth portion, 42 · .. Convex portion 44 .. Output shaft (rotating shaft) 44A .. Serration portion (fixed portion)

Claims (8)

A first molded body having a first half-split tooth portion on its outer peripheral portion and a second molded body having a second half-split tooth portion on its outer peripheral portion are coupled together in the axial direction, and the first half-split tooth portion and the second half-split tooth portion are provided on the outer peripheral portion, and the tooth bottom portion between the tooth portions is recessed in an arc shape so as to move toward the center side in the axial direction. a wheel body;
a rotating shaft fixed as an integrally molded product to the axial center of the first molded body;
with
The first molded body includes a disc-shaped main body, a fitting portion annularly projecting from a radially outer portion of the main body toward one axial side of the main body, and the main body. and a boss portion cylindrically projecting from the radially central portion of the body portion to both sides in the axial direction of the main body portion,
The second molded body is formed in an annular shape, and the fitting portion is fitted inside the second molded body,
A worm wheel in which the first molded body and the second molded body are joined by welding, adhesion or bolting. 2. The worm wheel according to claim 1, wherein the tip of the tooth portion is formed with an arcuate tip concave portion that is concentric with the tooth bottom portion. 3. The projection or recess formed on the outer peripheral surface of the fitting portion and the recess or projection formed on the inner peripheral surface of the second molded body are fitted to each other . Worm wheel as described. The worm wheel according to any one of claims 1 to 3, wherein the first molded body and the second molded body are made of different materials . Claims 1 to 4, wherein the rotary shaft has a fixed portion formed on the outer peripheral surface with unevenness arranged in a circumferential direction, and the fixed portion is embedded in the axial center portion of the first molded body. The worm wheel according to any one of . The first molded body and the second molded body are joined together in a state that the first half-split tooth part and the second half-split tooth part are displaced in the circumferential direction of the worm wheel main body. A worm wheel according to any one of claims 1 to 5. A method for manufacturing a worm wheel according to claim 6,
a mounting step of mounting the first molded body and the second molded body on a jig to which a worm is fixed, and engaging the first half-split tooth portion and the second half-split tooth portion with the teeth of the worm; ,
The first molded body and the second molded body are welded and bonded in a state in which the first half-split tooth part and the second half-split tooth part are displaced in the circumferential direction and brought into close contact with the tooth part of the worm. Or a joining step of joining by bolting,
A method for manufacturing a worm wheel having a motor;
a worm rotated by the motor;
a worm wheel according to any one of claims 1 to 6 meshed with the worm;
A motor device with

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