Worm

Abstract

The present invention addresses the problem of providing a worm capable of simplifying a manufacturing process and having good rotational balance. A first tapered portion (35b) is provided with a cutting start portion (71) forming one end of a tooth bottom portion (74), a second tapered portion (35c) is provided with a cutting end portion (72) forming the other end of the tooth bottom portion (74), and the tooth bottom portion (74) extends in a spiral shape from the cutting start portion (71) toward one circumferential side (counterclockwise direction) of the worm (35). The position of the cutting end section (72) is disposed within an angle range (38 degrees) of less than 90 degrees, the angle range being centered on the center of rotation of the worm (35) (equal to the center of rotation (C) of the rotating shaft (34)) and the angle range being the other side in the circumferential direction (clockwise direction) of the worm (35) with respect to the position of the cutting start section (71).

Description

Technical Field

[0001] This invention relates to a worm gear for gear engagement. Background Technology

[0002] For example, Patent Document 1 describes adjusting the length of the worm, the lead angle of the teeth, and the chamfers provided at both ends of the worm along the axial direction to obtain a worm with good rotational balance.

[0003] [Existing technical documents]

[0004] [Patent Literature]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2020-169721 Summary of the Invention

[0006] [The problem the invention aims to solve]

[0007] However, the technology described in Patent Document 1 requires determining two adjustment elements, namely the lead angle of the teeth and the chamfers provided at both ends of the worm along the axial direction, relative to the specified length of the worm, which complicates the manufacturing process of the worm.

[0008] The purpose of this invention is to provide a worm gear that simplifies the manufacturing process and provides good rotational balance.

[0009] [Technical means to solve the problem]

[0010] In one embodiment of the worm gear, which is a gear meshing worm gear, the worm gear has: a main body portion; a first cone portion connected to one axial side of the main body portion, having a shape that tapers towards the tip as it moves away from the main body portion; a second cone portion connected to the other axial side of the main body portion, having a shape that tapers towards the tip as it moves away from the main body portion; helical teeth arranged helically on the outer periphery of the first cone portion, the main body portion, and the second cone portion, including a tooth tip and a tooth base; a first tooth base end portion disposed on the first cone portion, forming one end of the tooth base; and a second tooth base end portion disposed on the second cone portion, forming the other end of the tooth base, the tooth base extending helically from the first tooth base end portion toward one circumferential side of the worm gear, the position of the second tooth base end portion being configured within an angle range of less than 90 degrees relative to the position of the first tooth base end portion on the other circumferential side of the worm gear, centered on the rotation center of the worm gear.

[0011] [The effects of the invention]

[0012] This invention provides a worm gear that simplifies the manufacturing process and achieves good rotational balance. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of a sunroof device installed on the roof of a vehicle.

[0014] Figure 2 This is a 3D view of the sunroof motor viewed from the output gear side.

[0015] Figure 3 This is a three-dimensional view of the sunroof motor as seen from the side of the cover component.

[0016] Figure 4 It is a cross-sectional view along the axial direction of the sunroof motor's rotation axis.

[0017] Figure 5 This is a three-dimensional view of the rotor as seen from the worm side.

[0018] Figure 6 It is Figure 5 A magnified 3D view of the worm gear.

[0019] Figure 7 This is a diagram of the rotating shaft unit viewed from a direction orthogonal to the axial direction.

[0020] Figure 8 yes Figure 6 AR arrow view.

[0021] Figure 9 It is a chart that uses 30-degree units to represent the relationship between the position of the cutting end and the balance of the rotation axis.

[0022] Figure 10 It is a chart that uses 5-degree units to represent the relationship between the position of the cutting end and the balance of the rotation axis.

[0023] Figure 11 It is a graph that uses 1 degree as a unit to represent the relationship between the position of the cutting end and the balance of the rotating axis.

[0024] Figure 12 It is a graph showing the relationship between the position of the cutting end and static values.

[0025] Figure 13 This is a table (n=32) showing the balance of the rotation axis when the position of the cutting end is offset by 35 degrees in the clockwise direction.

[0026] Figure 14 This is a table (n=30) showing the balance of the rotation axis when the position of the cutting end is offset by 38 degrees clockwise.

[0027] Explanation of icon numbers

[0028] 10: Sunroof installation

[0029] 11: Roof panel

[0030] 12: Vehicles

[0031] 13: Roof

[0032] 14: Opening

[0033] 15a, 15b: Base plate

[0034] 16: Guide rail

[0035] 17a, 17b: Drive cables

[0036] 20: Sunroof motor

[0037] 30: Electric Motor Department

[0038] 31: Motor housing

[0039] 31a: Side wall portion

[0040] 31b: Bottom wall portion

[0041] 32: Stator

[0042] 32a: Stator core

[0043] 32b: Tooth-like structure

[0044] 32c: Insulator

[0045] 33: Rotor

[0046] 33a: Rotor core

[0047] 33b: Magnetic support

[0048] 34: Rotation axis

[0049] 34a: Rotating shaft body

[0050] 34b: Small-diameter cylindrical section (second small-diameter section)

[0051] 34c: Tapered connecting part

[0052] 34d: Bearing support section (first minor diameter section)

[0053] 35: Worm gear

[0054] 35a: Main body

[0055] 35b: First cone

[0056] 35c: Second cone

[0057] 36: Ball bearing

[0058] 36a: Inner circle

[0059] 36b: Outer ring

[0060] 36c: Ball bearing

[0061] 37: Sensor Magnet Unit

[0062] 37a: Carrier component

[0063] 37b: Sensor magnet

[0064] 38: Adjusting components

[0065] 39: Support Components

[0066] 39a: Supporting structure

[0067] 39b: Wall

[0068] 39c: Annular support portion

[0069] 40: Speed ​​Reduction Mechanism

[0070] 41: Gearbox

[0071] 42: First wall section

[0072] 43: Second wall section

[0073] 44: Third wall section

[0074] 45: Worm Gear Housing

[0075] 46: Worm gear (or worm gear)

[0076] 46a: Tooth

[0077] 47: Output shaft

[0078] 47a: Output gear

[0079] 48: Cover component

[0080] 49: Worm Gear Reception Section

[0081] 49a: Conductive component support

[0082] 50: Bearing Installation Department

[0083] 51: Motor Housing Department

[0084] 60: Metal jacket

[0085] 70: Spiral teeth

[0086] 71: Cutting start section (first tooth root end, starting point)

[0087] 72: Cutting end section (end point of the second tooth)

[0088] 73: Tooth tip

[0089] 74: Tooth base

[0090] AG: Air gap

[0091] BR1: First Bearing

[0092] BR2: Second bearing

[0093] BT: Lathe tool

[0094] CL: Coil

[0095] EP: Conductive component

[0096] FG: Windshield

[0097] MC: Meshing Center

[0098] MG: Magnet

[0099] SC: Fixing screw

[0100] SD: Speed ​​reduction mechanism

[0101] W: Workpiece Detailed Implementation

[0102] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0103] Figure 1 A schematic diagram of a sunroof device installed on the roof of a vehicle is shown. Figure 2 This image shows a perspective view of the sunroof motor from the output gear side. Figure 3 A perspective view of the sunroof motor as seen from the side of the cover component is shown. Figure 4 A cross-sectional view along the axial direction of the rotation axis of the sunroof motor is shown. Figure 5 A perspective view of the rotor as seen from the worm side is shown. Figure 6 Showing will Figure 5 A magnified 3D view of the worm gear. Figure 7 A diagram showing the rotating shaft unit viewed from a direction orthogonal to the axial direction is provided. Figure 8 Show Figure 6 AR arrow view.

[0104] <Skylight Installation>

[0105] like Figure 1 As shown, the sunroof device 10 includes a roof panel 11. The roof panel 11 allows for the opening and closing of an opening 14 formed in the roof 13 of the vehicle 12. On both sides of the roof panel 11 in the vehicle width direction ( Figure 1 The upper and lower sides are respectively fixed with a pair of base plates (shoe) 15a and 15b.

[0106] Additionally, on both sides of the opening 14 in the width direction of the vehicle, along the front-rear direction of the vehicle 12, are fixed respectively. Figure 1 The guide rail 16 extends in the left and right directions. Moreover, a pair of base plates 15a and 15b are each guided by a pair of guide rails 16, thereby allowing the roof panel 11 to move in the front and rear directions of the vehicle 12.

[0107] Located on the rear side of vehicle 12 ( Figure 1 On the right side, a pair of base plates 15b are respectively connected to one end of drive cables 17a and 17b with gears. The other ends of these drive cables 17a and 17b are guided to the front side of the vehicle 12, closer to the opening 14. Figure 1 (on the left side).

[0108] Additionally, a sunroof motor 20 is installed inside the roof 13 between the windshield FG and the opening 14 in the longitudinal direction of the vehicle 12. Furthermore, the other ends of a pair of drive cables 17a and 17b are engaged with the output gear 47a of the sunroof motor 20.

[0109] Therefore, when the sunroof motor 20 is driven, a pair of drive cables 17a and 17b move in opposite directions along their length. As a result, the roof panel 11 is pushed and pulled by the pair of drive cables 17a and 17b via a pair of base plates 15b, thereby opening and closing the opening 14.

[0110] <Sunroof Motor>

[0111] like Figures 2 to 4 As shown, the sunroof motor 20 includes an electric motor section 30 and a reduction gear section 40. These electric motor sections 30 and reduction gear sections 40 are fixed together by a total of three fixing screws SC.

[0112] <Electric Motor Section>

[0113] The electric motor unit 30 is a brushless motor and has a motor housing 31 formed into a bottomed cylindrical shape by deep drawing or other processes on steel plates. The motor housing 31 includes the outer contour forming the electric motor unit 30 and is connected to the rotation shaft 34 (see reference). Figure 4 The sidewall portion 31a, whose cross-section is formed in the axial direction orthogonal to the deceleration mechanism portion 40, is approximately hexagonal. Furthermore, the side of the sidewall portion 31a opposite to the side of the deceleration mechanism portion 40 in the axial direction... Figures 2 to 4 The right side) is blocked by the stepped bottom wall 31b.

[0114] <Stator>

[0115] like Figure 4As shown, a stator 32 is housed inside the motor housing 31. The stator 32 has a stator core 32a formed by stacking multiple thin steel plates. The stator core 32a includes a total of six teeth 32b (details not shown) and is fixed to the inside of the motor housing 31. Furthermore, three-phase coils CL, including the U-phase, V-phase, and W-phase, are wound and mounted on the six teeth 32b via insulators 32c.

[0116] <Rotor>

[0117] like Figure 4 and Figure 5 As shown, a rotor 33 is rotatably mounted on the radially inner side of the stator 32 via a predetermined air gap AG. The rotor 33 rotates relative to the stator 32 and has a rotor core 33a formed in a generally cylindrical shape. The rotor core 33a is formed by stacking multiple thin steel plates, and a total of four magnets MG are mounted on the radially outer side of the rotor core 33a. Specifically, the four magnets MG are arranged at equal intervals (90-degree intervals) circumferentially on the rotor core 33a.

[0118] Furthermore, the radially outer side of the magnet MG mounted on the rotor core 33a is covered by a generally cylindrical magnet support 33b made of a thin stainless steel plate or the like. The magnet support 33b has the function of preventing the magnet MG from falling off the rotor core 33a. Therefore, even if the rotor 33 rotates at high speed, the magnet MG will not fall off the rotor core 33a due to the centrifugal force at that time.

[0119] <Rotation axis>

[0120] A rotating shaft 34 is fixed to the rotation center of the rotor core 33a by pressing. That is, the rotating shaft 34 is integrally rotatable on the rotor 33. Furthermore, to ensure sufficient strength, the rotating shaft 34 is made of round steel bar.

[0121] On the axial base end side of the rotating shaft 34 ( Figure 4 , Figure 5 On the right side, a rotating shaft body 34a is provided. The rotating shaft body 34a is rotatably housed inside the motor housing 31 and is supported by a first bearing BR1 installed in the bottom wall portion 31b of the motor housing 31 for free rotation.

[0122] In contrast, on the axial top side of the rotating shaft 34 ( Figure 4 , Figure 5 On the left side, a worm gear 35 is provided. The worm gear 35 is rotatably housed inside the gearbox 41 that forms the reduction mechanism section 40. In addition, the axial top end side of the rotating shaft 34 is supported by a second bearing BR2 installed in the worm gear housing section 49 of the gearbox 41, allowing it to rotate freely.

[0123] Thus, the rotating shaft 34 is rotatably housed inside both the motor housing 31 and the gearbox 41.

[0124] The worm gear 35 is integrally mounted on the rotating shaft 34, forming the reduction mechanism SD. Therefore, the worm gear 35 is also made of a round steel bar with sufficient strength. As a result, the worm gear 35 will not bend and reliably meshes with the worm wheel 46 during the drive of the sunroof motor 20.

[0125] <Ball Bearings>

[0126] A ball bearing 36 is installed at the axial center of the rotating shaft 34 and on the side of the worm 35 along the axial direction of the rotating shaft body 34a. That is, the ball bearing 36 is positioned axially between the first bearing BR1 and the second bearing BR2 of the rotating shaft 34, supporting the axial center of the rotating shaft 34 for free rotation. Furthermore, a rotor core 33a equipped with a magnet MG is positioned axially between the ball bearing 36 and the first bearing BR1, and the worm 35 is positioned between the ball bearing 36 and the second bearing BR2.

[0127] The ball bearing 36 includes: an inner ring 36a, which is formed of steel in a generally cylindrical shape; and an outer ring 36b, which is also formed of steel in a generally cylindrical shape, but has a larger diameter than the inner ring 36a. Furthermore, a plurality of balls 36c are disposed between the inner ring 36a and the outer ring 36b. Moreover, the inner ring 36a is press-fitted to the rotating shaft body 34a and is capable of rotating together with the rotating shaft 34.

[0128] <Sensor Magnet Unit>

[0129] Additionally, a sensor magnet unit 37 is disposed axially between the worm gear 35 and the ball bearing 36 on the rotating shaft 34. The sensor magnet unit 37 includes a cylindrical support member 37a, which is fixed to the rotating shaft body 34a by pressing; and a sensor magnet 37b, which is held in the support member 37a. Here, the sensor magnet 37b is used to detect the rotational state of the rotating shaft 34 (rotor 33), specifically the direction of rotation or the number of revolutions.

[0130] In addition, the sensor magnet unit 37, like the inner ring 36a of the ball bearing 36, is also capable of rotating together with the rotating shaft 34.

[0131] <Adjusting Components>

[0132] Furthermore, in the axial direction of the rotating shaft 34, between the ball bearing 36 and the rotor core 33a (magnet MG), an adjustment member 38 is arranged for adjusting the rotational balance of the rotor 33. The adjustment member 38 is formed into a generally cylindrical shape by stacking multiple thin steel plates and is fixed to the rotating shaft body 34a by pressing.

[0133] The adjusting member 38 has the following function: to suppress the rotational wobbling of the rotor 33 caused by minute positional misalignments between the rotation center of the rotation axis 34 (which varies for each product) and the rotation center of the rotor core 33a. Specifically, during the assembly of the rotor 33, the outer periphery of the adjusting member 38 is locally shaved while the rotor 33 is rotated to perform a balancing operation. As a result, the rotational balance of the rotor 33 is optimized.

[0134] Therefore, the rotational oscillation of the rotor 33 is suppressed, the operating noise of the sunroof motor 20 is reduced, and thus the quietness is improved. In particular, since the sunroof motor 20 is positioned above the head of the driver or passenger, its operating noise can be harsh when loud. Therefore, it is important, especially in the sunroof motor 20, to further improve quietness.

[0135] Furthermore, to further improve quietness, it is ideal to arrange the adjustment members 38 on both axial sides of the relatively heavy rotor core 33a and magnet MG, and to perform balancing work by locally cutting each adjustment member 38. However, if the adjustment members 38 are added to the axial base end side of the rotating shaft 34, the balancing work is time-consuming, and it is impossible to avoid the increase in size or weight of the sunroof motor 20 (electric motor part 30). Therefore, in the sunroof motor 20 of this embodiment, only one adjustment member 38 is provided on the rotor 33, which is only necessary to a minimum.

[0136] As in this embodiment, by providing only one adjustment member 38, the overall static imbalance of the rotor 33 can be effectively reduced. On the other hand, since balancing is performed only on one side of the rotor core 33a and the magnet MG, the overall dynamic imbalance of the rotor 33 worsens when the phases of the rotational oscillations during right rotation and left rotation are opposite.

[0137] Therefore, when considering both static and dynamic imbalances and ensuring good overall rotational balance of the rotor 33, it is important to minimize these imbalances as much as possible on a per-component basis. Thus, in this embodiment, the imbalance within the worm 35 (rotation shaft 34) is reduced by studying the shape of the helical teeth 70 that form the worm 35. Furthermore, the detailed shape of the helical teeth 70 (worm 35) will be described in detail later.

[0138] <Support Components>

[0139] The electric motor unit 30 includes a support member 39. The support member 39 is formed into a predetermined shape from a resin material such as plastic. The support member 39 has a support body 39a, which is formed into a generally flat plate shape; and a wall portion 39b that enters into the gearbox 41. That is, the support member 39 is a part mounted on the gearbox 41.

[0140] An annular support portion 39c is integrally provided on the support body 39a of the bracket member 39. The annular support portion 39c extends axially from the electric motor portion 30 side ( Figure 4 The outer ring 36b of the ball bearing 36 is located on the right side. Furthermore, the worm gear housing 49 side of the outer ring 36b in the axial direction... Figure 4 The left side is supported by the bearing mounting part 50 provided in the gearbox 41.

[0141] Thus, the outer ring 36b of the ball bearing 36 is held in the axial direction of the rotating shaft 34 by the gearbox 41 and the support member 39. In addition, the support member 39 fixes the motor housing 31 to the gearbox 41 with a total of three fixing screws SC, thereby fixing it without wobbling inside the gearbox 41.

[0142] In addition, multiple conductive components EP are installed on the support body 39a, corresponding to the three-phase coils CL. Specifically, a total of three conductive components EP are provided corresponding to the U-phase, V-phase, and W-phase (see reference). Figure 3 Thus, the support member 39 holds a total of three conductive members EP. Furthermore, the conductive members EP are formed into a generally rod-shaped form from brass or other materials with excellent conductivity, such as... Figure 4 As shown, it extends axially along the rotation axis 34.

[0143] Here, on the electric motor section 30 side along the length of each conductive component EP ( Figure 4 The right side) is electrically connected to the three-phase coil CL. On the other hand, the side of each conductive member EP opposite to the electric motor section 30 in the length direction ( Figure 4The left side of the gearbox 41 is supported by a conductive member support 49a. Furthermore, the portion of the conductive member EP supported by the conductive member support 49a is electrically connected to the connecting vehicle 12 (see reference EP). Figure 1 The control board (not shown) of the external connector (not shown) on the side.

[0144] Thus, drive current is supplied from the vehicle controller and other sources to each coil CL, thereby causing the rotating shaft 34 to rotate clockwise (forward) or counterclockwise. In this way, the support member 39 supports the outer ring 36b of the ball bearing 36 and holds a total of three conductive members EP.

[0145] <Deceleration Mechanism Section>

[0146] like Figures 2 to 4 As shown, the reduction mechanism section 40 includes a gearbox 41 that houses the reduction mechanism SD. The gearbox 41 is formed from a resin material such as plastic into a generally flat cuboid shape and is aligned with the motor housing 31 in the axial direction of the rotation shaft 34. Specifically, the gearbox 41 has a first wall portion 42, a second wall portion 43, and a third wall portion 44.

[0147] Inside the gearbox 41, a worm gear housing 45 is provided. The worm gear housing 45 is located near the third wall portion 44. Inside the worm gear housing 45, a worm gear 46 forming the reduction mechanism SD is rotatably housed. Furthermore, the worm gear 46 is made of resin material such as plastic, which enables weight reduction.

[0148] The worm gear 46 is provided with teeth 46a, which mesh with the worm 35 inside the gearbox 41. Furthermore, the reduction mechanism SD is formed by the worm 35 and the worm gear 46. In addition, the worm gear 46 is a spur gear, equivalent to the gear of the present invention.

[0149] Thus, the reduction mechanism SD becomes a worm gear reducer that can achieve a relatively large reduction ratio. Specifically, in this embodiment, the reduction ratio of the reduction mechanism SD is [1 / 67]. That is, it is the reduction ratio at which the worm wheel 46 ultimately rotates at 1 when the worm 35 rotates at 67. Of course, other reduction ratios can also be set.

[0150] Additionally, at the rotation center of the worm gear 46, the axial base end side of the output shaft 47, formed of a round steel bar, is fixed. On the other hand, at the axial top end side of the output shaft 47, a pair of drive cables 17a and 17b (see reference) are integrally provided. Figure 1 The meshing output gear 47a (refer to) Figure 2 ).

[0151] Thus, the high-speed rotation of the rotating shaft 34 is reduced by the reduction mechanism SD, and the reduced and high-torque rotational force is transmitted to a pair of drive cables 17a and 17b via the output shaft 47 and the output gear 47a.

[0152] Here, the worm gear receiving portion 45 has an opening (not shown) on the side opposite to the first wall portion 42. The opening of the worm gear receiving portion 45 is as follows: Figure 3 As shown, the cover component 48 is formed into a roughly circular plate shape by pressing and processing steel plates.

[0153] In addition, such as Figure 4 As shown, a worm housing 49 is provided inside the gearbox 41. The worm housing 49 is located near the second wall portion 43. Moreover, the worm housing 49 and the worm gear housing 45 are side by side, and the interiors of the worm housing 49 and the worm gear housing 45 are interconnected. Therefore, the worm 35 and the teeth 46a mesh with each other inside the gearbox 41.

[0154] The worm gear receiving portion 49 extends axially along the rotation axis 34, and is located on the bottom side of the worm gear receiving portion 49. Figure 4 (on the left side), housing the axial top end side of the rotating shaft 34 ( Figure 4 The left side is supported by a freely rotating second bearing BR2.

[0155] Furthermore, a conductive member support 49a is disposed between the worm gear housing 49 and the second wall portion 43. The conductive member support 49a functions to support the conductive member EP held in the support member 39 on the side opposite to the electric motor portion 30 in the longitudinal direction. Figure 4 The left side of the support is designed to prevent wobbling. This allows the control board (not shown) to be electrically connected to each conductive component EP in a stable state.

[0156] Additionally, a bearing mounting section 50 is provided inside the gearbox 41. The bearing mounting section 50 is positioned axially on the electric motor section 30 side of the worm gear receiving section 49. Figure 4 The right side of the bearing housing 30 opens towards the motor housing 31. Inside the bearing mounting section 50, a ball bearing 36 is housed. The bearing mounting section 50 is located on the side opposite to the electric motor section 30 in the axial direction of the outer ring 36b. Figure 4 Support it on the left side.

[0157] Thus, the rotating shaft 34 is supported at three points: the first bearing BR1, the second bearing BR2, and the ball bearing 36. Therefore, when the sunroof motor 20 is operating, it is possible to prevent the worm 35 from disengaging from the teeth 46a of the worm wheel 46 (the situation of mutual disengagement) and to reliably transmit power.

[0158] Furthermore, an inner ring 36a is fixed to the main body 34a of the rotating shaft 34, and the outer ring 36b is held by the bearing mounting part 50 and the support member 39. Therefore, the rotating shaft 34 will not move along its axial direction. Thus, it is not necessary to arrange thrust bearings on both sides of the axial direction of the rotating shaft 34, which can reduce the number of parts.

[0159] <Motor Containment Department>

[0160] like Figure 4 As shown, a motor housing 51, which is generally box-shaped, is provided inside the gearbox 41. The motor housing 51 is arranged axially on the motor housing 31 side of the bearing mounting section 50 along the rotating shaft 34. Figure 4 (on the right side). Moreover, a portion of the electric motor unit 30 is housed in the motor housing 51. Specifically, the wall portion 39b of the support member 39 that forms the electric motor unit 30 enters the motor housing 51.

[0161] <Metal Jacket>

[0162] like Figure 2 and Figure 3 As shown, a metal sleeve 60, formed by bending a thin steel plate, is partially installed on the outer side of the gearbox 41. The metal sleeve 60 functions to prevent electrical noise generated inside the gearbox 41 from radiating to the outside of the gearbox 41. Therefore, electrical noise will not reach the vehicle 12 (see reference 12). Figure 1 Car audio systems (not shown) can suppress the generation of radio noise, etc.

[0163] <Detailed Structure of the Rotation Axis>

[0164] Next, the detailed structure of the rotating shaft 34 will be described in detail using the accompanying drawings.

[0165] like Figure 6 and Figure 7 As shown, the rotating shaft 34 includes a rotating shaft body 34a and a worm gear 35. The axial length of the rotating shaft 34 is L1 (114.5 mm). The axial length of the rotating shaft body 34a is L2 (72.0 mm), which is shorter than the overall length L1 of the rotating shaft 34 (L2 < L1). The axial length of the worm gear 35 is L3 (32.0 mm), which is shorter than the length L2 of the rotating shaft body 34a (L3 < L2).

[0166] Furthermore, the outer diameter of the rotating shaft body 34a is D1 (8.0 mm), and the outer diameter of the worm gear 35 is D2 (7.3 mm), which is smaller than the outer diameter D1 of the rotating shaft body 34a (D2 < D1).

[0167] Furthermore, the main body 34a of the rotating shaft is disposed on the axial base end side of the rotating shaft 34, and the worm gear 35 is disposed on the axial top end side of the rotating shaft 34. Here, in Figure 7 In the text, the worm gear 35 is represented by a shaded area for easier understanding. Additionally, in... Figure 7 Detailed illustrations of the helical teeth 70 forming the worm 35 are omitted (see reference). Figure 6 ).

[0168] The rotating shaft body 34a has no components formed on its outer periphery and is a simple cylindrical shape extending straight along the axial direction. Therefore, the rotating shaft body 34a itself has good rotational balance and hardly causes rotational wobbling. In other words, the rotating shaft body 34a does not need to adjust its rotational balance.

[0169] Furthermore, along the axial direction of the rotating shaft 34, a small-diameter cylindrical portion 34b and a tapered connecting portion 34c are provided between the rotating shaft body 34a and the worm gear 35. Specifically, along the axial direction of the rotating shaft 34, the small-diameter cylindrical portion 34b is positioned near the worm gear 35, and the tapered connecting portion 34c is positioned near the rotating shaft body 34a.

[0170] Furthermore, the outer diameter of the small-diameter cylindrical portion 34b is D3 (6.0 mm), which is smaller than the outer diameter D1 of the rotating shaft body 34a and the outer diameter D2 of the worm gear 35 (D3 < D2 < D1). In addition, the axial length of the small-diameter cylindrical portion 34b is L4 (0.8 mm).

[0171] The tapered connecting portion 34c has a roughly frustum-shaped form, with its outer diameter gradually changing to smoothly connect the rotating shaft body 34a and the small-diameter cylindrical portion 34b. Specifically, the outer diameter of the portion of the tapered connecting portion 34c near the rotating shaft body 34a is D1, and the outer diameter of the portion of the tapered connecting portion 34c near the small-diameter cylindrical portion 34b is D3. Furthermore, the axial length of the tapered connecting portion 34c is L5 (2.0 mm).

[0172] Here, the small-diameter cylindrical portion 34b and the tapered connecting portion 34c also have no components formed on their outer periphery, and are respectively formed as a simple cylindrical shape and a frustum-cone shape. Therefore, even in the small-diameter cylindrical portion 34b and the tapered connecting portion 34c, the rotational balance is good, and almost no rotational wobbling is caused. That is, like the rotating shaft body 34a, the small-diameter cylindrical portion 34b and the tapered connecting portion 34c do not require adjustment of their rotational balance.

[0173] Furthermore, by providing a small-diameter cylindrical portion 34b and a tapered connecting portion 34c between the worm gear 35 and the rotating shaft body 34a, the lathe cutting tool BT used during the forming of the helical teeth 70 (see reference) is prevented from being damaged. Figure 7In the case of contact with the rotating shaft body 34a, the small-diameter cylindrical portion 34b and the tapered connecting portion 34c function as "relief grooves" for the lathe cutting tool BT.

[0174] Furthermore, a bearing support 34d is provided on the axial tip side of the worm gear 35. Like the main body of the rotating shaft 34a, the bearing support 34d has no components formed on its outer periphery, exhibiting a simple cylindrical shape. Therefore, even within the bearing support 34d, rotational balance is good, and rotational wobble is almost nonexistent. Thus, even within the bearing support 34d, there is no need to adjust its rotational balance.

[0175] Here, the bearing support 34d is composed of the second bearing BR2 (refer to...). Figure 4 The support is a freely rotatable part, and its axial length is L6 (7.7 mm), which is longer than the axial length L4 of the small-diameter cylindrical part 34b and the axial length L5 of the tapered connecting part 34c (L6 > L5 > L4). In addition, the outer diameter of the bearing support part 34d is D4 (6.7 mm), which is larger than the outer diameter D3 of the small-diameter cylindrical part 34b (D4 > D3).

[0176] <worm gear>

[0177] The worm 35 is integrally mounted on the portion of the rotating shaft 34 near the axial tip. Furthermore, helical teeth 70 are provided on the outer periphery of the worm 35 (see reference). Figure 6 The helical teeth 70 are formed by rotating the round steel bar (workpiece) that serves as the axis of rotation 34 while abutting against the lathe tool BT from its radially outer side (see reference). Figure 7 The outer periphery of the workpiece is cut into a spiral shape. Thus, the helical teeth 70 are formed using a lathe and extend spirally along the axial direction of the workpiece. Therefore, the worm 35 (helical teeth 70) is a machined product.

[0178] Here, the number of helical teeth 70 is "1". In this embodiment, as described above, the reduction mechanism SD (refer to...) Figure 4 The reduction ratio is [1 / 67], therefore the number of teeth 46a of the worm wheel 46 meshing with the worm 35 is "67".

[0179] Additionally, the worm 35 includes a main body 35a, which has teeth 46a for the worm wheel 46 (see reference). Figure 4 The meshing center MC of the meshing. Furthermore, as... Figure 6 and Figure 7As shown, the main body 35a is disposed at the axial center of the worm 35. Furthermore, the worm 35 includes: a first tapered portion 35b, which is connected to the axial top end side (one axial side) of the main body 35a; and a second tapered portion 35c, which is connected to the axial base end side (the other axial side) of the main body 35a.

[0180] Specifically, along the axial direction of the worm 35, the first cone 35b exhibits a shape where the diameter gradually decreases and the tip becomes increasingly thinner as it moves away from the main body 35a. Similarly, along the axial direction of the worm 35, the second cone 35c also exhibits a shape where the diameter gradually decreases and the tip becomes increasingly thinner as it moves away from the main body 35a.

[0181] Furthermore, the axial top end side of the first tapered portion 35b is connected to the bearing support portion 34d, and the axial base end side of the second tapered portion 35c is connected to the small-diameter cylindrical portion 34b. That is, on the side of the first tapered portion 35b in the axial direction of the worm 35 opposite to the side of the main body portion 35a, a bearing support portion 34d with a diameter smaller than that of the main body portion 35a is provided, and on the side of the second tapered portion 35c in the axial direction of the worm 35 opposite to the side of the main body portion 35a, a small-diameter cylindrical portion 34b with a diameter smaller than that of the main body portion 35a is provided.

[0182] Furthermore, the bearing support portion 34d corresponds to the first minor diameter portion of the present invention. Additionally, the minor diameter cylindrical portion 34b corresponds to the second minor diameter portion of the present invention.

[0183] Spiral teeth

[0184] like Figure 6 As shown, the helical teeth 70 extend in a helical shape along the axial direction of the worm 35, and are formed by cutting on a lathe from the axial top end side to the axial base end side. Specifically, the helical teeth 70 are helically arranged on the outer periphery of the first cone portion 35b, the main body portion 35a, and the second cone portion 35c of the worm 35.

[0185] Here, on the tip side of the spiral tooth 70 along its length ( Figure 6 On the left side, a cutting start section 71 is provided, which serves as the starting point for the cutting process. The cutting start section 71 is a lathe tool BT (see reference BT). Figure 7 The inlet portion of the spiral teeth 70. On the other hand, on the base end side in the length direction of the spiral teeth 70 ( Figure 6 On the right side, a cutting end portion 72 is provided, which serves as the end position (end point) of the cutting process. The cutting end portion 72 is a lathe tool BT (refer to...). Figure 7 The discharge section of ).

[0186] Specifically, the cutting start portion 71 is disposed on the first cone portion 35b forming the worm 35, and the cutting end portion 72 is disposed on the second cone portion 35c forming the worm 35. Here, the first cone portion 35b and the second cone portion 35c are so-called incomplete portions that do not function as gears. By providing the cutting start portion 71 on the first cone portion 35b and the cutting end portion 72 on the second cone portion 35c, the transmission efficiency of the reduction mechanism SD can be improved, and the reduction mechanism SD can operate smoothly.

[0187] In other words, in this embodiment, the rotational balance of the worm 35 is adjusted using the incomplete portions of the worm 35, namely the first cone portion 35b and the second cone portion 35c, as described later. That is, in this embodiment, the incomplete portions of the worm 35 are effectively utilized.

[0188] Furthermore, a tooth tip 73 is provided on the outer periphery of the helical tooth 70. Moreover, a tooth root 74 is provided in the portion that is radially recessed by the lathe cutting tool BT of the lathe. That is, the helical tooth 70 includes a tooth tip 73 and a tooth root 74. Furthermore, the cutting start portion 71 forms the longitudinal end portion (one end) of the tooth root 74, and the cutting end portion 72 forms the longitudinal base portion (the other end) of the tooth root 74.

[0189] Furthermore, the cutting start portion 71 corresponds to the first tooth root end portion of the present invention. Additionally, the cutting end portion 72 corresponds to the second tooth root end portion of the present invention.

[0190] Thus, the helical teeth 70 are formed by alternating tooth tips 73 and tooth bases 74 along the axial direction of the worm 35. Furthermore, in the helical teeth 70 of this embodiment, the pressure angle is set to "11.0 degrees", the module is set to "0.700", and the pitch is set to "2.199 mm".

[0191] Furthermore, the helical teeth 70 provided in the worm 35 are helically connected in the axial direction of the worm 35. Therefore, the position of the centroid of the cross-section in the direction orthogonal to the axial direction of the worm 35, and the position of the rotation center of the worm 35, are offset in different directions in a part of the worm 35 and other parts in the axial direction. Therefore, compared with the rotating shaft body 34a, the small-diameter cylindrical part 34b, the tapered connecting part 34c, and the bearing support part 34d, which have no parts formed on their outer periphery, it can be said that the rotational balance of the worm 35 is poor.

[0192] Furthermore, as described above, poor rotational balance of the worm 35 can induce rotational oscillation of the rotating shaft 34, on which the worm 35 is integrally mounted. Therefore, for the electric motor section 30 (see reference...) Figure 4This applies a load, causing the sunroof motor 20 to operate with increased noise. Therefore, in this embodiment, the worm gear 35, like the other parts of the rotating shaft 34, is designed to maintain good rotational balance as much as possible.

[0193] In this embodiment, to ensure good rotational balance of the worm 35, such as Figure 8 As shown, when the worm 35 is viewed axially, the position of the cutting end portion 72, which is the endpoint, is adjusted relative to the position of the cutting start portion 71, which is the starting point, in the circumferential direction of the worm 35. That is, in this embodiment, by offsetting the position of the cutting end portion 72 relative to the position of the cutting start portion 71 by a predetermined angle in the circumferential direction of the worm 35, the overall rotational wobbling of the worm 35 is suppressed. As a result, the rotational balance of the worm 35 unit, and consequently the overall rotational balance of the rotating shaft 34, becomes good.

[0194] Specifically, in Figure 7 In the rotation axis 34 of the physique shown, as Figure 8 As shown, the tooth base 74 of the spiral tooth 70 extends in a spiral manner from the cutting start point 71 (starting point) toward the circumferential side of the worm 35 (counterclockwise). Furthermore, the cutting end point 72 (end point) is positioned within an angle range of less than 90 degrees relative to the cutting start point 71 (0 degrees) on the other circumferential side of the worm 35 (clockwise), specifically at 38 degrees.

[0195] That is, the cutting end portion 72 is offset at an acute angle relative to the cutting start portion 71 in the clockwise direction of the worm 35. It is determined that by setting the helical teeth 70 to this shape, the overall rotational balance of the rotating shaft 34 becomes the best (the balance amount [g·mm] of the rotating shaft 34 becomes optimal).

[0196] <Regarding the machining sequence of helical teeth and the position of the cutting end>

[0197] The angle formed by the position of the cutting start point 71 (starting point) and the position of the cutting end point 72 (end point) (in) Figure 8 The optimal value (the acute angle side in the clockwise direction) was determined by preparing multiple samples (prototypes) for research. The results are described in detail below.

[0198] Figure 9 A graph showing the relationship between the position of the cutting end and the balance of the rotation axis, expressed in 30-degree units. Figure 10 A graph showing the relationship between the position of the cutting end and the balance of the rotation axis, expressed in 5-degree units. Figure 11A graph showing the relationship between the position of the cutting end and the balance of the rotation axis, expressed in units of 1 degree. Figure 12 A graph showing the relationship between the position of the cutting end and static values ​​is presented. Figure 13 A table showing the balance of the rotation axis when the position of the cutting end is offset by 35 degrees clockwise (n=32) is displayed. Figure 14 A table showing the balance of the rotation axis when the position of the cutting end is offset by 38 degrees clockwise (n=30).

[0199] Here, before explaining the results of the study on the position of the cutting end portion 72, we will use... Figure 8 The process details the machining sequence of the helical teeth 70 (tooth bottom 74) using a lathe, i.e. the forming sequence (cutting sequence) of the worm 35.

[0200] <Machining sequence of spiral teeth>

[0201] Figure 8 The symbol C indicates the rotation center of the chuck (not shown) mounted on the lathe spindle, on which the workpiece W (round steel bar) is mounted as the rotation axis 34. That is, the rotation center C of the lathe spindle and chuck coincides with the rotation center of the rotation axis 34 after the cutting process is completed.

[0202] Additionally, a lathe tool BT is disposed radially outside the workpiece W, which is mounted on the chuck. The lathe tool BT is configured to approach or move away from the workpiece W from its radially outer side. The lathe tool BT is capable of... Figure 8 The two-dot dashed arrow M1 and the two-dot dashed arrow M2 can move in the direction of the rotation center C, and thus can also move along the axis of the rotation center C. Figure 8 It can move along the depth direction. As a result, a helical tooth 70 (tooth bottom 74) can be formed along its axial direction on the outer periphery of the workpiece W.

[0203] First, place the lathe tool BT against the cutting start point 71 (see reference). Figure 8 The part with the black dots, namely the first cone 35b (refer to the black dot). Figure 7 ) part, and Figure 8 The part shown at 0 degrees, and rotate the workpiece W in the direction of arrow RT (clockwise). Then, gradually move the lathe tool BT in the direction of the two-dot arrow M1, and gradually towards the axial base end side of the workpiece W ( Figure 8 The inside and Figure 7 The tooth moves to the right side. Thus, the tooth root 74 (see reference) is formed in a manner that gradually deepens radially inward from the cutting start portion 71 toward the workpiece W. Figure 6Additionally, the tooth base 74 is formed to a certain depth equal to the tooth height of the helical tooth 70, and is formed in a helical manner toward the axial base end side of the workpiece W in a counterclockwise direction.

[0204] That is, such as Figure 8 As indicated by the dashed arrow pointing to the start of cutting, the portion of the tooth base 74 near the start of cutting 71 is shallow. As it moves away from the start of cutting 71, the depth of the tooth base 74 increases, eventually reaching a depth equal to the tooth height dimension of the helical tooth 70. Thus, the helical tooth 70 (tooth base 74) is formed at a predetermined interval (2.199 mm).

[0205] Subsequently, in the portion on the axial base end side of the worm 35, specifically the second cone 35c (refer to...) Figure 7 The lathe tool BT is gradually moved towards the direction of the two-dot arrow M2 near the point where the cutting tool BT is located. As a result, the depth of the tooth root 74 machined by the lathe tool BT gradually decreases towards the cutting end 72 (see reference). Figure 8 (The cutting ends as indicated by the dashed arrow).

[0206] Furthermore, from the start of the cut indicated by the dashed arrow to the end of the cut, the lathe tool BT rotates multiple times relative to the workpiece W. As a result, the helical tooth 70 (tooth base 74) is formed in a helical manner advancing in the counter-clockwise direction, and the position of the cutting end portion 72 on the counter-clockwise side (obtuse angle side) is 322 degrees. In contrast, relative to the position of the cutting start portion 71 (0 degrees), the position of the cutting end portion 72 on the clockwise side (acute angle side) is 38 degrees.

[0207]

[0208] Next, a model of the rotating axis 34 is created using a computer, and the optimal position of the cutting end point 72 relative to the position of the cutting start point 71 is simulated. The following will use... Figures 9 to 14 The research results will be described in detail.

[0209] First, such as Figure 9 As shown, the position of the cutting end point 72 relative to the position of the cutting start point 71 (0 degrees) is varied in the clockwise direction (acute angle side) within the range of 0 to 180 degrees <in 30-degree increments> to simulate the balance amount [g·mm] of the rotation axis 34. Thus, the balance amount [g·mm] of the rotation axis 34 shows a minimum of 0.02255 [g·mm] at the 30-degree mark.

[0210] Next, as Figure 10As shown, to further improve the resolution, the position of the cutting end 72 where the balance amount [g·mm] of the rotation axis 34 decreases is simulated <in 5-degree units>. Thus, in the case of <in 5-degree units>, the balance amount [g·mm] of the rotation axis 34 shows a minimum of 0.01390 [g·mm] at 40 degrees of the circular mark.

[0211] Thus, in the case of <30-degree units>, the balance of the rotation axis 34 at 30 degrees [g·mm] shows a minimum value of 0.02255 [g·mm], and in the case of <5-degree units>, the balance of the rotation axis 34 at 40 degrees [g·mm] shows a minimum value of 0.01390 [g·mm]. The angular difference between these two values ​​is 10 degrees, neither of which can be considered an accurate value. Therefore, to further increase the resolution, simulations are performed <in 1-degree units>. Thus, as... Figure 11 As shown, it is determined that the balance of the rotating shaft 34 [g·mm] is the smallest at 38 degrees, which is close to 40 degrees, and is 0.01327 [g·mm].

[0212] In the cutting process on a lathe, based on the size of the workpiece W (refer to...), Figure 7 However, some degree of error may occur. Specifically, the position of the cutting end point 72 (the acute angle side in the clockwise direction) relative to the position of the cutting start point 71 (0 degrees) may not be as precisely determined as the target. Therefore, in this embodiment, the size of the workpiece W (refer to...) is derived from the position of the cutting end point 72. Figure 7 The desired range is determined by machining to converge within the range, thereby achieving good rotational balance for the rotating shaft 34 of the sunroof motor 20.

[0213] Specifically, in this embodiment, such as Figure 11 As shown in the shaded area, by setting the position of the cutting end portion 72 at an acute angle relative to the position of the cutting start portion 71 (0 degrees) within the range of 37 to 40 degrees (angle range) marked by the circle, the balance amount [g·mm] of the rotation shaft 34 becomes an optimal value that can also be fully applied to the sunroof motor 20. Furthermore, the balance amount [g·mm] of the rotation shaft 34 at this time shows 0.01390 [g·mm] or less.

[0214] Here, several samples of the rotating shaft 34 are prepared for each position (each angle) of the cutting end portion 72 to confirm whether these samples also exhibit the same tendency as the simulation. Thus, as... Figure 12 Average (AVE) and Figure 13As shown, when the cutting end 72 is at a position of 35 degrees, the static value [g·mm] becomes the minimum (n=32, see shaded area).

[0215] However, as Figure 14 As shown, if the balance of the rotating shaft 34 [g·mm] (dynamic imbalance: right / left) is observed, then, as in the simulation, the position of the cutting end 72 at 38 degrees is smaller than that at 35 degrees (n=30, see shaded area).

[0216] Therefore, in the sunroof motor 20, since the vibration or noise generated during its operation becomes a problem, 38 degrees, which shows a smaller value in dynamic imbalance, is adopted as the optimal position of the cutting end 72. In this embodiment, the 38 degrees is taken as the approximate center value in the range of 37 to 40 degrees (the optimal angle range).

[0217] also, Figure 12 The dashed "analysis value" represents the simulation results obtained by the computer.

[0218] As described in detail above, according to this embodiment, a cutting start portion 71 forming one end of a tooth bottom 74 is provided in the first cone portion 35b, and a cutting end portion 72 forming the other end of a tooth bottom 74 is provided in the second cone portion 35c. The tooth bottom 74 extends in a spiral manner from the cutting start portion 71 toward the circumferential side (counterclockwise direction) of the worm 35. The position of the cutting end portion 72 is arranged within an angle range of less than 90 degrees (38 degrees) with the rotation center of the worm 35 (which is the same as the rotation center C of the rotation axis 34) as the center, and the position of the cutting start portion 71 is on the other circumferential side (clockwise direction) of the worm 35.

[0219] Therefore, the rotational balance of the rotating shaft 34 with the worm gear 35 can be achieved. Thus, even a rotor 33 with an adjustment member 38 on only one side of the rotor core 33a and the magnet MG (see reference) can achieve good rotational balance. Figure 5 This allows both static imbalance and dynamic imbalance to be combined into a well-balanced rotational equilibrium. Therefore, it enables the electric motor unit 30 (sunroof motor 20) to achieve further improved quietness.

[0220] Furthermore, the helical tooth 70 can be designed based on only one adjustment element, namely the offset (deviation value) of the position of the cutting end 72 relative to the position of the cutting start 71. Therefore, the manufacturing process of the rotating shaft 34, including the worm 35, can be simplified, reducing time costs.

[0221] Furthermore, according to this embodiment, a bearing support portion 34d with a smaller diameter than the main body portion 35a is provided on the side of the first tapered portion 35b opposite to the side of the main body portion 35a in the axial direction of the worm 35, and a small-diameter cylindrical portion 34b with a smaller diameter than the main body portion 35a is provided on the side of the second tapered portion 35c opposite to the side of the main body portion 35a in the axial direction of the worm 35.

[0222] Therefore, the axial sides of the worm 35 can function as "relief grooves" for the lathe tool BT, thereby forming the tooth root 74 (helical tooth 70) with good precision from the first cone portion 35b (incomplete portion) through the main body portion 35a to the second cone portion 35c (incomplete portion). This improves the transmission efficiency of the gear forming the reduction mechanism SD and allows the reduction mechanism SD to operate more smoothly.

[0223] Furthermore, according to this embodiment, the manufacturing process of the rotating shaft 34, including the worm gear 35, can be simplified, thus enabling energy saving in manufacturing. This achieves, in particular, Goal 7 (ensuring access to affordable, reliable and sustainable modern energy for all) and Goal 13 (taking urgent action to address climate change and its impacts) of the United Nations Sustainable Development Goals (SDGs).

[0224] The present invention is not limited to the described embodiments, and various modifications can be made without departing from its spirit. In the described embodiments, the present invention is shown to be applied to the worm gear 35 of the sunroof motor 20, but the present invention is not limited thereto, and can also be applied, for example, to the worm gear of a motor device used in the drive source of a vehicle's sliding door device, power window device, windshield wiper device, etc.

[0225] Furthermore, the material, shape, size, quantity, and placement of each component in the embodiments are arbitrary as long as they achieve the present invention, and are not limited to the embodiments described.

Claims

1. A worm gear for meshing with gears, The worm gear has: Main body; The first conical portion is connected to one axial side of the main body portion and has a shape that becomes increasingly tapered at the tip as it moves away from the main body portion. The second conical portion is connected to the other side of the axial direction of the main body portion and has a shape that becomes increasingly tapered at the tip as it moves away from the main body portion. Spiral teeth are spirally arranged on the outer periphery of the first cone portion, the main body portion, and the second cone portion, including a tooth tip and a tooth base; The first tooth root end is disposed at the first cone portion, forming one end of the tooth root; and The second tooth root end is located at the second cone portion, forming the other end of the tooth root. The tooth base extends in a spiral manner from the first tooth base end toward one circumferential side of the worm, and the position of the second tooth base end is configured within an angle range of less than 90 degrees relative to the position of the first tooth base end on the other circumferential side of the worm, with the rotation center of the worm as the center.

2. The worm gear according to claim 1, wherein, The angle range is from 37 degrees to 40 degrees.

3. The worm gear according to claim 1 or 2, wherein, On the side of the first tapered portion in the worm gear, opposite to the main body portion, a first minor diameter portion with a smaller diameter than the main body portion is provided. On the side opposite to the main body portion of the second tapered portion along the axial direction of the worm, a second minor diameter portion with a smaller diameter than the main body portion is provided.

4. The worm gear according to claim 3, wherein, The worm gear is a machined product.

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