JP2017082859A - Gear and steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gear capable of improving coupling force between a tooth part and a resin sleeve in such a structure that the tooth part is connected to the resin sleeve, and a steering device including the gear.SOLUTION: A gear 22 includes a resin sleeve 37 formed into a disc shape, and a tooth part 36 at least covering an outer peripheral part 46 of the sleeve 37 and formed with a gear tooth 31. On the outer peripheral part 46, an outer peripheral rib 50 and an outer peripheral flange 48 are provided. The outer peripheral rib 50 extends in an axial direction X of the sleeve 37 while projecting toward a radial outside Z1 of the sleeve 37, and is engaged with the tooth part 36. The outer peripheral flange 48 extends in a circumferential direction Y of the sleeve 37 while projecting toward the radial outside Z1, is engaged with the tooth part 36, and is connected to the outer peripheral rib 50.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a gear and a steering apparatus including the gear.

  The gear wheel disclosed in Patent Document 1 below is a resin-made outer peripheral part in which gear teeth are formed on the outer peripheral surface, a metal insert formed in a hub shape, and a resin-made connecting the outer peripheral part and the insert. It is comprised by three separate parts called the connection part of this. The connecting part has a disk shape, and the outer peripheral part covers only the outer peripheral part of the connecting part.

European Patent Application Publication No. 1777439A1

  In the case where the connecting part is made of resin like the gear wheel of Patent Document 1, there is a concern that the rigidity and strength of the connecting part are reduced compared to the case where the connecting part is made of metal. Therefore, for example, when an external force acts on the gear teeth of the outer peripheral part as power is transmitted by the gear wheel, the connecting part may be deformed or damaged, and the coupling force between the connecting part and the outer peripheral part may be reduced. There is.

  The present invention has been made under such a background. In a configuration in which a tooth portion is coupled to a resin sleeve, a gear capable of improving the coupling force between the sleeve and the tooth portion, and the gear are provided. An object of the present invention is to provide a steering device including the same.

  The invention according to claim 1 is a resin sleeve (37) formed in a disk shape, provided on the outer peripheral portion (46), and protruding toward the outer side (Z1) in the radial direction (Z) of the sleeve. An outer peripheral rib (50) extending in the axial direction (X) of the sleeve, and provided in the outer peripheral portion, extending in the circumferential direction (Y) of the sleeve while projecting outward in the radial direction, and connected to the outer peripheral rib. A sleeve having an outer peripheral flange (48), and a tooth portion (36) that covers at least the outer peripheral portion and is engaged by the outer peripheral rib and the outer peripheral flange to form gear teeth (31). It is a gear (22) characterized by these.

According to a second aspect of the present invention, the tooth portion includes a first portion (41) that covers the outer peripheral portion and a second portion (37A) that covers a front portion (37A) on one side (X1) in the axial direction of the sleeve. 42) The gear according to claim 1, further comprising a front rib (55) provided on the front portion, projecting toward the one side, and engaging the second portion. It is.
The invention according to claim 3 is the gear according to claim 2, characterized in that the outer peripheral rib and the front rib are connected.

Invention of Claim 4 contains the electric motor (19) driven based on steering of a steering member (2), and the gear in any one of Claims 1-3, The output rotation of the said electric motor is carried out. A steering device (1) including a speed reducer (20) decelerated by the gear and transmitted to the steering mechanism (6).
In addition, in the above, the numbers in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

According to the first and fourth aspects of the present invention, the gear includes a disk-shaped resin sleeve and a tooth portion that covers at least the outer peripheral portion of the sleeve and has gear teeth.
An outer peripheral rib and an outer peripheral flange are provided on the outer peripheral portion. The outer peripheral rib extends in the axial direction of the sleeve while protruding outward in the radial direction of the sleeve, and engages with the tooth portion. As a result, it is possible to prevent the teeth from coming off in the circumferential direction of the sleeve. The outer peripheral flange extends in the circumferential direction while protruding outward in the radial direction, and is engaged with the tooth portion. As a result, it is possible to prevent the tooth portion from coming off in the axial direction. The outer peripheral rib and the outer peripheral flange reinforce each other by being connected. Since the outer peripheral rib and the outer peripheral flange having improved rigidity and strength are strong, they can be firmly engaged with the tooth portion.

As a result, it is possible to improve the coupling force between the sleeve and the tooth portion.
According to the invention described in claim 2, the tooth portion integrally includes a first portion that covers the outer peripheral portion of the sleeve and a second portion that covers the front portion on one side in the axial direction of the sleeve.
In the sleeve, in addition to the outer peripheral rib and outer peripheral flange provided on the outer peripheral portion engaging with the first portion, the front rib provided on the front portion is engaged with the second portion. In this way, when all of the outer peripheral rib, outer peripheral flange and front rib are engaged with the tooth portion, the force acting near the boundary between the sleeve and the tooth portion along with the transmission of power by the gear is Dispersed in each of the front ribs. Thereby, the burden which each of an outer periphery rib, an outer periphery flange, and a front rib receives in the case of transmission of the motive power by a gear becomes small. For this reason, the outer peripheral rib, the outer peripheral flange, and the front rib are not easily deformed, and can be firmly engaged with the tooth portion. Moreover, the area | region engaged with a tooth | gear part in a sleeve is ensured comparatively widely by being comprised by an outer periphery rib, an outer periphery flange, and a front rib.

As a result, the coupling force between the sleeve and the tooth portion can be further improved.
According to invention of Claim 3, the outer peripheral rib and the front rib mutually reinforce by connecting. Since the outer peripheral rib and the front rib having improved rigidity and strength are strong, they can be firmly engaged with the tooth portion. For this reason, the coupling force between the sleeve and the tooth portion can be further improved.

FIG. 1 is a schematic view of a steering apparatus according to an embodiment of the present invention. FIG. 2 is a front view of a gear used in the reduction gear of the steering device. FIG. 3 is a rear view of the gear. 4 is a cross-sectional view taken along line AA in FIG. FIG. 5 is a side view of a sleeve included in the gear. FIG. 6 is a front view of the sleeve. FIG. 7 is a rear view of the sleeve. 8 is a cross-sectional view taken along the line BB in FIG. 9 is a cross-sectional view taken along the line CC in FIG. FIG. 10 is a cross-sectional view of a gear according to a first modification. FIG. 11 is a schematic cross-sectional view showing a gear manufacturing method. FIG. 12 is a schematic cross-sectional view showing the next step of FIG. FIG. 13 is a schematic cross-sectional view showing the next step of FIG. FIG. 14 is a schematic cross-sectional view showing a modification of the gear manufacturing method. FIG. 15 is a front view of a gear sleeve according to a second modification. FIG. 16 is a cross-sectional view of a gear according to a third modification.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic view of a steering apparatus 1 according to an embodiment of the present invention. Referring to FIG. 1, a steering device 1 is an electric power steering device, includes a steering mechanism 6 and a steering mechanism 4, and is based on steering (steering operation) of a driver's steering wheel 2 (steering member). The steered wheel 3 is steered. The steering mechanism 6 includes an assist mechanism 5 that assists the driver's steering operation.

  The steering mechanism 6 has an input shaft 8, an output shaft 9, an intermediate shaft 7 and a pinion shaft 15. The input shaft 8 is connected to the steering wheel 2. The output shaft 9 is connected to the input shaft 8 via a torsion bar 10. The intermediate shaft 7 is connected to a pinion shaft 15 having a pinion 15a through a universal joint.

The steered mechanism 4 has a rack shaft 16 and a tie rod 17. The rack shaft 16 has a rack 16a meshed with the pinion 15a. The tie rod 17 has one end connected to the rack shaft 16 and the other end connected to the steered wheel 3.
When the steering wheel 2 rotates in accordance with the driver's operation of the steering wheel 2, the pinion shaft 15 rotates through the input shaft 8, the output shaft 9 and the intermediate shaft 7. The rotation of the pinion shaft 15 is converted into a reciprocating motion in the axial direction of the rack shaft 16 by the steering mechanism 4. The turning angle of the steered wheels 3 is changed by the reciprocating motion of the rack shaft 16 in the axial direction.

The assist mechanism 5 includes a torque sensor 11, an ECU (Electronic Control Unit) 12, an electric motor 19, and a speed reducer 20.
The speed reducer 20 includes a worm 21, a gear 22 configured as a worm wheel that meshes with the worm 21, and a housing 23 that houses the worm 21 and the gear 22. The worm 21 is connected to a rotating shaft (not shown) of the electric motor 19. The gear 22 is connected to the output shaft 9 so as to be integrally rotatable.

  When the steering wheel 2 rotates with the driver's steering, the torque sensor 11 detects the amount of twist between the input shaft 8 and the output shaft 9. The ECU 12 determines the assist torque based on the steering torque T obtained from the amount of twist detected by the torque sensor 11, the vehicle speed V detected by the vehicle speed sensor 13, and the like. The electric motor 19 is driven and controlled by the ECU 12. Thus, the electric motor 19 driven based on the steering of the steering wheel 2 transmits the output rotation to the worm 21 to rotate the worm 21. Then, the gear 22 meshed with the worm 21 rotates at a lower speed than the worm 21, and the gear 22 and the output shaft 9 rotate integrally. Thus, the speed reducer 20 decelerates the output rotation of the electric motor 19 by the gear 22 and transmits it to the output shaft 9 of the steering mechanism 6 as an assist torque. This assists the steering operation of the steering wheel 2 by the driver.

Next, the gear 22 will be described in detail. FIG. 2 is a front view of the gear 22. FIG. 3 is a rear view of the gear 22. 4 is a cross-sectional view taken along line AA in FIG.
Referring to FIG. 2, gear 22 is formed in a disc shape. A direction perpendicular to the paper surface of FIG. 2 is the axial direction X of the gear 22. The axial direction X is also the thickness direction of the gear 22. The central axis J of the gear 22 extends in the axial direction X through the circle center of the gear 22. In the axial direction X, the front side in FIG. 2 is referred to as the front side X1 of the gear 22, and the back side in FIG. The front side X1 is one side in the axial direction X, and the back side X2 is the opposite side to the one side in the axial direction X.

  A circular through hole 30 penetrating the gear 22 along the axial direction X is formed at the center of the circle of the gear 22. When the output shaft 9 is press-fitted into the through hole 30, the gear 22 is coupled to the output shaft 9 so as to be integrally rotatable. A large number of gear teeth 31 that mesh with the worm 21 are formed at equal intervals in the circumferential direction Y of the gear 22 over the entire outer peripheral portion of the gear 22. A gap between adjacent gear teeth 31 is formed in a groove shape in which the outer peripheral portion of the gear 22 is cut out in the axial direction X. When the worm 21 rotates with the gear teeth 31 engaged with the worm 21, the gear 22 rotates in the circumferential direction Y.

  The gear 22 includes a collar 35, a tooth portion 36, and a sleeve 37. Hereinafter, each of the collar 35, the tooth portion 36, and the sleeve 37 will be described using the axial direction X, the front side X1, the back side X2, the circumferential direction Y, and the radial direction Z of the gear 22. In the radial direction Z, a direction away from the central axis J toward the outer peripheral portion of the gear 22 is referred to as a radial outer side Z1, and a direction toward the central axis J is referred to as a radial inner side Z2.

  The collar 35 is formed in a metal annular shape having a central axis that coincides with the central axis J. The through hole 30 of the gear 22 is defined by an inner peripheral surface 35 </ b> A of the collar 35. A flange 38 that protrudes radially outward Z1 and extends in the circumferential direction Y is integrally provided substantially at the center in the axial direction X on the outer circumferential surface 35B of the collar 35 (see FIG. 4). The flange 38 is provided over the entire area in the circumferential direction Y on the outer circumferential surface 35 </ b> B, but may be provided only in a partial region in the circumferential direction Y. A plurality of convex portions 39 projecting radially outward Z1 are integrally provided in a region on the back surface side X2 from the flange 38 in the outer peripheral surface 35B (see FIG. 3). These convex portions 39 have a substantially triangular shape that narrows toward the radially outer side Z1 when viewed from the axial direction X, and are arranged at equal intervals in the circumferential direction Y. The convex portion 39 has a rib shape extending in the axial direction X. The convex portion 39 may be connected to the flange 38.

The tooth part 36 is made of resin. The tooth portion 36 integrally includes a first portion 41 and a second portion 42.
The first part 41 is formed in an annular shape, the axial direction thereof coincides with the axial direction X, the circumferential direction thereof coincides with the circumferential direction Y, and the radial direction thereof coincides with the radial direction Z. Yes. Referring to FIG. 4, the first portion 41 has a thickness in the axial direction X. The outer peripheral surface 41A of the first portion 41 is curved along the circumferential direction Y. In the first portion 41, the front surface 41B located on the front side X1 and the back surface 41C located on the back side X2 are flat along the radial direction Z. A chamfer 41D is formed across the entire circumferential direction Y at the boundary between the outer peripheral surface 41A and the rear surface 41C. The outer peripheral surface 41A and the portions connected to the outer peripheral surface 41A in each of the front surface 41B and the back surface 41C constitute the outer peripheral portion of the first portion 41. The gear teeth 31 described above are formed on the outer periphery of the first portion 41. A groove 41 </ b> F extending in the circumferential direction Y while being recessed toward the radially outer side Z <b> 1 is formed in a region of the inner peripheral surface 41 </ b> E of the first portion 41 that is biased toward the back side X <b> 2. The groove 41F is provided over the entire area in the circumferential direction Y on the inner peripheral surface 41E, but may be provided only in a partial region in the circumferential direction Y.

  The second portion 42 projects from the end portion of the first portion 41 on the front side X1 to the radially inner side Z2. The second part 42 is formed in an annular shape extending in the circumferential direction Y (see FIG. 2). The second portion 42 may not be a complete annular shape, and may be interrupted in the middle in the circumferential direction Y. The surface portion on the front side X1 in the second portion 42 will be referred to as a front portion 42A. The front part 42A is an annular first front part 42B that extends flatly in the circumferential direction Y along the radial direction Z, and extends to the rear side X2 while continuously expanding from the first front part 42B. And a tapered second front portion 42 </ b> C connected to the front surface 41 </ b> B of 41. That is, the second front part 42C, which is a part of the front part 42A, is formed in a taper shape toward the back side X2 as it goes to the radially outer side Z1.

  The sleeve 37 is formed in a disc shape, and its axial direction coincides with the axial direction X, its circumferential direction coincides with the circumferential direction Y, and its radial direction coincides with the radial direction Z. The entire sleeve 37 is made of resin. Since not only the tooth portion 36 but also the sleeve 37 is made of resin, the entire gear 22 can be reduced in weight. Examples of the resin constituting the sleeve 37 include a resin in which glass fiber (GF) or the like is mixed with nylon such as PA66. The glass fiber contributes to suppression of the dimensional change of the sleeve 37. The ratio of the glass fiber to this resin is, for example, about 50%.

The sleeve 37 extends in the radial direction Z and connects the inner circumferential portion 45 and the outer circumferential portion 46 extending in the radial direction Z. And a connecting portion 47 to be integrated.
The inner peripheral portion 45 is formed in an annular shape having a central axis that coincides with the central axis J. In the axial direction X, the inner peripheral portion 45 has the same dimensions as the collar 35. The thickness of the inner peripheral portion 45 in the radial direction Z is substantially the same in the entire region in the axial direction X. The diameter of the inner peripheral surface 45A of the inner peripheral portion 45 is the same as the diameter of the outer peripheral surface of the outer peripheral surface 35B of the collar 35. A groove 45B extending in the circumferential direction Y while being recessed toward the radially outer side Z1 is formed at a substantially center in the axial direction X on the inner circumferential surface 45A. The groove 45B is provided over the entire area in the circumferential direction Y on the inner circumferential surface 45A, but may be provided only in a partial area in the circumferential direction Y. In the inner peripheral surface 45A, a plurality of concave portions 45C that are recessed toward the radially outer side Z1 are formed in the region on the back side X2 from the groove 45B (see FIG. 3). These concave portions 45C have a substantially triangular shape that narrows toward the radially outer side Z1 when viewed from the axial direction X, and are arranged at equal intervals in the circumferential direction Y. The recess 45C has a groove shape extending in the axial direction X, and may be connected to the groove 45B.

  The outer peripheral portion 46 is formed in an annular shape and is arranged coaxially with the inner peripheral portion 45. The thickness of the outer peripheral portion 46 in the radial direction Z is substantially the same in the entire region in the axial direction X. In the axial direction X, the end portion 46A on the front side X1 of the outer peripheral portion 46 is substantially at the same position as the substantially central portion of the inner peripheral portion 45, and the end portion 46B on the back side X2 of the outer peripheral portion 46 is the inner peripheral portion 45. It protrudes to the back side X2 from the end of the back side X2. The diameter of the outer peripheral surface 46 </ b> C of the outer peripheral portion 46 is substantially the same as the diameter of the inner peripheral surface 41 </ b> E of the first portion 41 of the tooth portion 36. An outer peripheral flange 48 that protrudes radially outward Z1 and extends in the circumferential direction Y is integrally provided in a region of the outer peripheral surface 46C that is biased toward the back side X2.

Referring to FIG. 5 which is a side view of the sleeve 37 and FIG. 6 which is a front view of the sleeve 37, the outer peripheral flange 48 is provided over the entire area in the circumferential direction Y on the outer peripheral surface 46C. You may provide only in the one part area | region in the direction Y. FIG. A boundary portion 49 between the outer peripheral flange 48 and the outer peripheral surface 46C is rounded in an arc shape.
Referring to FIG. 5, a plurality of outer peripheral ribs 50 are provided in the outer circumferential surface 46 </ b> C so as to be arranged at equal intervals in the circumferential direction Y in the entire region in the circumferential direction Y in the region on the front side X <b> 1 from the outer circumferential flange 48. . Each outer peripheral rib 50 is formed in a rib shape extending in the axial direction X while projecting outward in the radial direction Z1. The end portions on the back side X <b> 2 of the respective outer peripheral ribs 50 are connected to the outer peripheral flange 48. When the outer peripheral surface 46C is used as a reference, the height T1 of the outer peripheral rib 50 in the radial direction Z is the same as or slightly lower than the height T2 of the outer peripheral flange 48 in the radial direction Z (see FIG. 6). ). Between the outer peripheral ribs 50 adjacent to each other in the circumferential direction Y, outer peripheral grooves 51 extending in the axial direction X while being recessed toward the radially inner side Z2 are formed one by one. The groove bottom of the outer peripheral groove 51 is constituted by an outer peripheral surface 46C. The outer peripheral rib 50 and the outer peripheral groove 51 constitute an outer peripheral engaging portion 52 provided in the outer peripheral portion 46.

  Referring to FIG. 4, the connecting portion 47 is formed in a thin annular shape in the axial direction X, and is arranged coaxially with each of the inner peripheral portion 45 and the outer peripheral portion 46. The connecting portion 47 is provided between the substantially central portion in the axial direction X in the inner peripheral portion 45 and the end portion 46 </ b> A on the front side X <b> 1 of the outer peripheral portion 46. A boundary portion 53 between the connecting portion 47 and the outer peripheral surface 45D of the inner peripheral portion 45 is rounded into an arc shape. An annular portion on the front side X1 from the connecting portion 47 in the inner peripheral portion 45 is referred to as a front flange 45E, and an annular portion on the back side X2 from the connecting portion 47 in the inner peripheral portion 45 is referred to as a rear flange 45F. . The front flange 45E is a part of the front portion 37A constituting the surface portion of the front side X1 of the sleeve 37, and extends in the circumferential direction Y while projecting to the front side X1 from the connecting portion 47 (FIGS. 5 and 6). reference). The back flange 45F is a part of the back surface portion 37B constituting the surface portion on the back surface side X2 of the sleeve 37, and extends in the circumferential direction Y while projecting from the connecting portion 47 to the back surface side X2 (see FIG. 7 described later). reference).

  A surface portion on the front side X1 in the connecting portion 47 is a part of the front portion 37A of the sleeve 37. The front surface portion is flat along the radial direction Z and extends in the circumferential direction Y. The annular first front portion 47A extends to the rear side X2 while continuously expanding from the first front portion 47A. And a tapered second front portion 47B connected to the outer peripheral surface 46C. That is, the second front surface portion 47B, which is a part of the front surface portion 37A, is formed in a tapered shape toward the back surface side X2 as it goes toward the radially outer side Z1. A boundary portion 54 between the second front portion 47B and the outer peripheral surface 46C is rounded into an arc shape.

  Referring to FIGS. 5 and 6, a plurality of front ribs 55 are provided in a region of the front side 37 </ b> A of the sleeve 37 that is radially outside Z <b> 1 from the front flange 45 </ b> E, that is, the first front side 47 </ b> A and the second front side 47 </ b> B. Are arranged at equal intervals in the circumferential direction Y. Each front rib 55 is formed in a rib shape extending in the radial direction Z while projecting to the front side X1. The ends of the radially inner Z2 of each front rib 55 are connected to the front flange 45E, and these front ribs 55 extend radially from the front flange 45E when viewed from the front side X1 (FIG. 6). reference). When the first front portion 47A is used as a reference, the height T3 of the front flange 45E in the axial direction X is higher than the height T4 of the front rib 55 in the axial direction X. In the front portion 37A, between the front ribs 55 adjacent in the circumferential direction Y, one front groove 56 extending in the radial direction Z while being recessed toward the back side X2 is formed. The groove bottom of the front groove 56 is constituted by a first front part 47A and a second front part 47B. The front rib 55 and the front groove 56 constitute a front engaging portion 57 provided in the front portion 37A.

  The front ribs 55 are provided in the same number as the outer peripheral ribs 50, and each front rib 55 is in the same position in the circumferential direction Y as any one of the outer peripheral ribs 50. The front rib 55 and the outer peripheral rib 50 at the same position in the circumferential direction Y are connected and integrated to form one rib. A connecting portion between the front rib 55 and the outer peripheral rib 50 is curved along a boundary portion 54 between the second front portion 47B and the outer peripheral surface 46C of the outer peripheral portion 46.

As in the case of the front rib 55 and the outer peripheral rib 50, the same number of front grooves 56 as the outer peripheral grooves 51 are provided, and each front groove 56 is located at the same position in the circumferential direction Y as any one of the outer peripheral grooves 51. The outer peripheral groove 51 and the front groove 56 at the same position in the circumferential direction Y are connected and integrated to form one groove.
FIG. 7 is a rear view of the sleeve 37. In FIG. 7, the back surface portion 37B of the sleeve 37 is illustrated. A plurality of recesses 58 that are recessed toward the front side X <b> 1 are formed in the back surface portion 37 </ b> B so as to be arranged at equal intervals in the circumferential direction Y. Thereby, weight reduction of the sleeve 37 can be achieved.

  A back surface rib 59 extending in the radial direction Z between these recesses 58 is integrally provided as a boundary between the adjacent recesses 58 on the back surface part 37B. The back rib 59 is constructed between the back flange 45F of the inner peripheral portion 45 and the outer peripheral portion 46, and is connected to the connecting portion 47 from the back side X2. Each concave portion 58 is a space sandwiched from the circumferential direction Y by the adjacent back ribs 59 and sandwiched from the radial direction Z by the back flange 45F and the outer peripheral portion 46, and is connected to the front side X1 by the connecting portion 47. Although it is blocked, it is open to the back side X2 (see also FIG. 4). The back rib 59 can ensure the rigidity and strength of the sleeve 37 around the recess 58.

  Referring to FIG. 8, which is a cross-sectional view taken along the line B-B in FIG. 2, each back rib 59 is provided at a position shifted from the front rib 55 in the circumferential direction Y. Referring to FIG. 9, which is a cross-sectional view taken along the line CC in FIG. 4, each back rib 59 is provided at a position shifted from the outer peripheral rib 50 in the circumferential direction Y. In this way, when the rear rib 59 is arranged so as to be shifted in the circumferential direction Y from each of the front rib 55 and the outer circumferential rib 50, the position in the circumferential direction Y is compared to the case where the rear rib 59 is arranged at the same position in the circumferential direction Y. As a result, it is possible to prevent the rigidity and strength of the sleeve 37 from greatly varying.

Next, referring to FIGS. 4, 8, and 9, a coupling structure between the collar 35 and the tooth portion 36 and the sleeve 37 will be described.
The sleeve 37 is fitted coaxially to the collar 35, and the flange 38 of the collar 35 is fitted into the groove 45B of the inner peripheral portion 45 of the sleeve 37 from the radially inner side Z2 (see FIG. 4). As a result, the collar 35 and the sleeve 37 are coupled so that they cannot move relative to each other in the axial direction X. Further, the convex portions 39 of the collar 35 are fitted into the concave portions 45C of the inner peripheral portion 45 one by one from the radially inner side Z2 (see FIG. 9). As a result, the collar 35 and the sleeve 37 are coupled so that they cannot move relative to each other in the circumferential direction Y.

  The outer peripheral flange 48 of the outer peripheral portion 46 of the sleeve 37 is engaged with the tooth portion 36 by fitting from the radially inner side Z2 into the groove 41F of the inner peripheral surface 41E of the first portion 41 of the tooth portion 36 ( (See FIG. 4). Thus, the tooth portion 36 and the sleeve 37 are coupled so as not to move relative to each other in the axial direction X. Therefore, even when a component force in the axial direction X of the power acts on the tooth portion 36 during power transmission by the gear 22, the tooth portion 36 in the axial direction X can be prevented from coming off.

  In the tooth portion 36, the first portion 41 covers the outer peripheral portion 46 of the sleeve 37 from the radially outer side Z1, and the second portion 42 is a region in the radially outer side Z1 of the front portion 37A of the sleeve 37 from the front flange 45E. All are covered from the front side X1 (refer FIG. 4). The first part 41 enters the outer peripheral groove 51 between the adjacent outer peripheral ribs 50 in the outer peripheral part 46 without any gap (see FIG. 9), and the second part 42 is between the adjacent front ribs 55 in the front part 37A. It has entered the front groove 56 without any gap (see FIG. 8). Thereby, the outer periphery engaging part 52 comprised by the outer peripheral rib 50 and the outer periphery groove | channel 51 engages with the 1st part 41, and the front engaging part 57 comprised by the front rib 55 and the front groove | channel 56 is 2nd. The portion 42 is engaged. Therefore, the tooth part 36 and the sleeve 37 are coupled so as not to move relative to each other in the circumferential direction Y. Therefore, even when a component force in the circumferential direction Y acts on the tooth portion 36 during power transmission by the gear 22, the tooth portion 36 can be prevented from coming off in the circumferential direction Y.

  As described above, when all of the outer peripheral flange 48, the outer peripheral engaging portion 52, and the front engaging portion 57 are engaged with the tooth portion 36, near the boundary between the sleeve 37 and the tooth portion 36 as power is transmitted by the gear 22. The acting force is distributed to each of the outer peripheral flange 48, the outer peripheral engaging portion 52, and the front engaging portion 57. Thereby, the load which each of the outer periphery flange 48, the outer periphery engaging part 52, and the front engaging part 57 receives in the case of transmission of the motive power by the gear 22 becomes small. Therefore, the outer peripheral flange 48, the outer peripheral engaging portion 52, and the front engaging portion 57 are not easily deformed, and can be firmly engaged with the tooth portion 36. Further, the region of the sleeve 37 that engages with the tooth portion 36 is constituted by the outer peripheral flange 48, the outer peripheral engagement portion 52, and the front engagement portion 57, so that it is relatively wide across the outer peripheral portion 46 and the front portion 37 </ b> A. Secured.

  Further, the outer peripheral rib 50 and the outer peripheral flange 48 reinforce each other by being connected. Since the outer peripheral rib 50 and the outer peripheral flange 48 having improved rigidity and strength are strong and difficult to deform, they can be firmly engaged with the tooth portion 36. This effect can also be obtained by the gear 22 (see FIG. 10) of the first modification in which the second portion 42 is omitted from the tooth portion 36 and the front engaging portion 57 is omitted from the sleeve 37.

  As a result, the coupling force between the sleeve 37 and the tooth portion 36 can be improved. Further, the coupling force between the sleeve 37 and the tooth portion 36 is improved, so that the rigidity of the gear 22, particularly the rigidity around the gear teeth 31 to which power is transmitted is improved. Thereby, even when the resin sleeve 37 is used, it is possible to stabilize the meshing between the gear teeth 31 of the gear 22 and the worm 21 when power is transmitted.

Further, the outer peripheral rib 50 of the outer peripheral engaging portion 52 and the front rib 55 of the front engaging portion 57 are connected to each other to reinforce each other (see FIG. 5). Since the outer peripheral rib 50 and the front rib 55 having improved rigidity and strength in this manner are strong and difficult to deform, they can be firmly engaged with the tooth portion 36. For this reason, the coupling force between the sleeve 37 and the tooth portion 36 can be further improved.
The front flange 45E of the sleeve 37 is in contact with the second portion 42 of the tooth portion 36 from the radially inner side Z2 over the entire region in the circumferential direction Y (see also FIG. 2). Therefore, even if a force such as a bending moment that tries to tilt the tooth portion 36 to the front side X1 acts on the tooth portion 36, the second portion 42 is supported and stretched by the front flange 45E. Can be prevented from coming off. This improves the rigidity and strength of both the tooth portion 36 and the sleeve 37 with respect to the bending moment toward the front side X1. Therefore, the meshing between the gear teeth 31 of the tooth portion 36 and the worm 21 during power transmission by the gear 22 can be stabilized.

In the sleeve 37, a front rib 55 provided on the front portion 37 </ b> A and protruding to the front side X <b> 1 is engaged with the second portion 42. Thereby, since the front portion 37 </ b> A of the sleeve 37 is firmly coupled to the second portion 42, it is possible to reliably suppress the tooth portion 36 from being detached from the sleeve 37.
Further, since the front rib 55 is reinforced by being connected to the front flange 45E, the rigidity and strength of the front rib 55 can be improved. As a result, the front rib 55 is sturdy and difficult to deform, and can be firmly engaged with the second portion 42 of the tooth portion 36. Therefore, the front portion 37 </ b> A of the sleeve 37 is more firmly coupled to the second portion 42, so that it is possible to more reliably suppress the tooth portion 36 from being detached from the sleeve 37.

  And since each front rib 55 is provided with an undercut, the cross-sectional shape of each front rib 55 when cut along the cut surface along the circumferential direction Y is the front side X1 as shown in FIG. It is getting thicker. In this case, since the front rib 55 is engaged with the second portion 42 from the front side X1, it is difficult to remove the second portion 42 from the front portion 37A of the sleeve 37 to the front side X1. Therefore, even if a force such as a bending moment that tries to incline the tooth portion 36 on the front side X1 acts on the tooth portion 36, the tooth portion 36 can be reliably prevented from coming off the sleeve 37. In order to acquire the same effect, the cross-sectional shape (refer FIG. 9) of the outer periphery rib 50 when cut | disconnected by the cut surface along the radial direction Z may become thick toward the radial direction outer side Z1.

  As described above, in the gear 22, the outer peripheral flange 48, the outer peripheral rib 50, the front flange 45E, and the front rib 55 are provided on the resin sleeve 37, and the outer peripheral flange 48 and the outer peripheral rib 50 are connected to each other. And the front rib 55 are connected, and the front flange 45E and the front rib 55 are connected. As a result, the weight of the sleeve 37 can be reduced, the coupling force between the tooth portion 36 and the sleeve 37 can be improved, and the rigidity and strength of the entire sleeve 37 can be improved.

Since the back ribs 59 of the sleeve 37 are reinforced by connecting the back ribs 59 to the back flange 45F of the inner peripheral portion 45 (see FIG. 3), the rigidity and strength of the back rib 59 and the sleeve 37 as a whole. Can be improved.
Next, a method for manufacturing the gear 22 will be described. 11 to 13 are schematic cross-sectional views showing a method for manufacturing the gear 22. In the following, for convenience of explanation, description will be made based on the vertical direction of FIGS. 11 to 13, but the vertical direction of FIGS. 11 to 13 may not be an actual vertical direction.

  Referring to FIG. 11, a first mold 65 is prepared. The first mold 65 can be divided vertically into a first split mold 66 and a second split mold 67. The first split mold 66 is provided with a columnar support portion 66A that protrudes upward, and a plurality of convex portions 66B that protrude upward and are arranged side by side so as to surround the support portion 66A. The convex portion 66 </ b> B has a shape that matches the concave portion 58 of the back surface portion 37 </ b> B of the sleeve 37. The portion around the support portion 66A on the upper surface of the first split mold 66 matches the contour of the back surface portion 37B. On the lower surface of the second split mold 67, a recess 67 </ b> A that coincides with the contour of the front portion 37 </ b> A of the sleeve 37 and the outer peripheral surface 46 </ b> C of the outer peripheral portion 46 is formed. The second split mold 67 is formed with a circular disc gate 67B that continues from above on the recess 67A, and a sprue 67C that continues from above on the disc gate 67B. The second split mold 67 may be separable into a portion where the recess 67A is formed and a portion where the disk gate 67B and the sprue 67C are formed. The sprue 67C is connected to a nozzle of an injection molding machine (not shown).

  As shown in FIG. 11, in a state where the collar 35 is externally fitted to the support portion 66 </ b> A of the first split mold 66, the second split mold 67 is lowered and the first mold 65 is closed. Then, in the first mold 65, an annular cavity 68 that matches the completed sleeve 37 is formed around the collar 35. The disk gate 67B is disposed coaxially with the cavity 68 and faces the cavity 68 from above. The melted resin supplied from the nozzle of the injection molding machine reaches the disk gate 67B through the sprue 67C and spreads radially from the disk gate 67B as indicated by the thick arrow, and the cavity 68 in the first mold 65 is spread. Injected into. When the resin that has reached the cavity 68 is cooled and hardened, the insert molding of the sleeve 37 is completed. The molded sleeve 37 is coupled to the collar 35.

  In the sleeve 37, the back rib 59 is determined to be provided at a position shifted from the front rib 55 in the circumferential direction Y. Specifically, the back rib 59 is provided at the same position as the front groove 56 in the circumferential direction Y. (See FIG. 8). Therefore, compared with the case where the back rib 59 is provided at the same position as the front rib 55 in the circumferential direction Y, the thickness in the axial direction X of the sleeve 37 after molding is suppressed from greatly varying according to the position in the circumferential direction Y. it can. As a result, when the sleeve 37 is molded with the molten resin, the cooling rate of the resin in the entire sleeve 37 can be made uniform, so that the occurrence of dimensional defects and molding defects in the sleeve 37 after cooling of the resin can be suppressed. Further, in such a sleeve 37, the thickness in the axial direction X as a whole is reduced, so that the amount of dimensional change due to temperature change can be suppressed.

  After forming the sleeve 37, a second mold 70 shown in FIG. 12 is prepared. The second mold 70 can be divided vertically into a first split mold 71 and a second split mold 72. The first split mold 71 is provided with a columnar support 71A that protrudes upward. The collar 35 to which the sleeve 37 is coupled is externally fitted to the support portion 71A. A portion around the sleeve 37 on the upper surface of the first split mold 71 coincides with the contour of the back side X2 of the tooth portion 36. On the lower surface of the second split mold 72, a recess 72 </ b> A that matches the contour of the front side X <b> 1 of the sleeve 37 is formed. The second split mold 72 is formed with a circular disc gate 72B continuous from above on the recess 72A and a sprue 72C continuous from above on the disc gate 72B. The second split mold 72 may be separable into a portion where the recess 72A is formed and a portion where the disk gate 72B and the sprue 72C are formed. The sprue 72C is connected to a nozzle of an injection molding machine (not shown).

As shown in FIG. 12, the collar 35 and the sleeve 37 are externally fitted to the support portion 71 </ b> A of the first split mold 71. At this time, in the sleeve 37, the front surface portion 37A faces upward, and the back surface portion 37B faces downward. Therefore, the upper side of FIG. 12 is the front side X1, and the lower side of FIG. 12 is the back side X2.
Next, the second split mold 72 is lowered and the second mold 70 is closed. Then, an annular cavity 73 that coincides with the completed tooth portion 36 is formed in the second mold 70 around the sleeve 37. The cavity 73 is a gap between the sleeve 37 set in the second mold 70 and the second mold 70. The disk gate 72B is disposed coaxially with the cavity 73 and faces the cavity 73 from above. The melted resin supplied from the nozzle of the injection molding machine reaches the disk gate 72B through the sprue 72C and spreads radially from the disk gate 72B as indicated by the thick arrow, and the cavity 73 in the second mold 70 is spread. Injected into.

  In the sleeve 37, a front engaging portion 57 constituted by the front rib 55 and the front groove 56 extends in the radial direction Z. Therefore, when the molten resin is poured into the front portion 37A of the sleeve 37 in the cavity 73 to form the tooth portion 36, the resin smoothly flows to the radially outer side Z1 by being guided by the front engaging portion 57. be able to. Further, the second front surface portion 47B of the front surface portion 37A of the sleeve 37 is formed in a taper shape toward the back surface side X2 as it goes toward the radially outer side Z1. Therefore, when the molten resin is flowed to the front portion 37A to form the tooth portion 36, the resin can smoothly flow to the radially outer side Z1 by being guided by the tapered second front portion 47B.

  Further, as described above, the second front part 42C of the front part 42A on the front side X1 in the second part 42 of the completed tooth part 36 is formed in a tapered shape toward the back side X2 as it goes to the radially outer side Z1. (See FIG. 4). In this case, the region 72D that coincides with the second front part 42C in the second split mold 72 also has a tapered shape along the second front part 42C. Therefore, when the molten resin is poured into the second mold 70 to form the tooth portion 36, the resin is smoothly guided to the radially outer side Z1 by being guided by the tapered region 72D in the second split mold 72. Can flow into.

  Further, when the resin flows into the gap 83 between the tapered region 72D and the tapered second front portion 47B of the front portion 37A of the sleeve 37, the thickness of the axial direction X is reduced by the resin flowing into the gap 83. The second portion 42 that is substantially constant over the direction Z can be formed. Thus, in the 2nd part 42 with which thickness became substantially constant, the cooling rate of the resin at the time of shaping | molding can be made uniform, and generation | occurrence | production of molding defects, such as a void and a dimension defect, can be suppressed.

As a result, the tooth portion 36 having a target shape for improving the coupling force with the sleeve 37 can be formed.
Also, by injecting the resin into the cavities 68 and 73 while spreading the resin radially using the disk gates 67B and 72B, it is possible to suppress the occurrence of molding defects such as weld marks in the sleeve 37 and the tooth portion 36 after molding. Thereby, the gear 22 which can aim at the improvement of the coupling | bonding force between the sleeve 37 and the tooth | gear part 36 can be manufactured.

  When the resin that has reached the cavity 73 is cooled and hardened, the semi-finished product 80 of the tooth portion 36 is completed as shown in FIG. The semi-finished product 80 is coupled to the sleeve 37. The resin remaining on the disk gate 72B is solidified to form a surplus portion 81, which closes the inner space of the collar 35 from the front side X1 as a part of the semi-finished product 80. Therefore, when the surplus portion 81 is cut and removed, the formation of the tooth portion 36 is completed. In addition, the semi-finished product 80 in which the surplus part 81 does not exist can be shape | molded by shape | molding using another division | segmentation type | mold (not shown) which blocks the internal space of the collar 35 from the front side X1.

Finally, when the gear teeth 31 are formed on the tooth portion 36 by cutting, the gear 22 is completed (see FIG. 4).
FIG. 14 is a schematic cross-sectional view showing a modification of the method for manufacturing the gear 22. 11 to 13, the manufacturing method for forming the tooth portion 36 after forming the sleeve 37 has been described. However, as shown in FIG. 14, the sleeve 37 may be insert-molded after the tooth portion 36 is formed.

  In FIG. 14, a third mold 85 is prepared. The third mold 85 is provided with a columnar support portion 85A that protrudes upward, and a plurality of convex portions 85B that protrude upward and are provided side by side so as to surround the support portion 85A. The convex portion 85 </ b> B has a shape that matches the concave portion 58 of the back surface portion 37 </ b> B of the sleeve 37. A portion around the support portion 85A on the upper surface of the third mold 85 coincides with the contour of the back surface portion 37B.

  As shown in FIG. 14, the tooth part 36 after molding is set on the third mold 85 so as to surround the collar 35 in a state in which the collar 35 is externally fitted to the support part 85 </ b> A of the third mold 85. . At this time, in the tooth part 36, the first part 41 is in contact with the upper surface of the third mold 85, and the second part 42 is in a state of floating from the third mold 85. Further, the convex portion 85 </ b> B of the third mold 85 is located between the collar 35 and the tooth portion 36. As a result, an annular cavity 86 coinciding with the completed sleeve 37 is formed between the third mold 85 and the tooth portion 36 so as to surround the collar 35. A disk gate (not shown) connected to the nozzle of the injection molding machine is disposed coaxially with the cavity 86 and faces the cavity 86 from above. The molten resin supplied from the nozzle of the injection molding machine reaches the disk gate, and is injected into the cavity 86 while spreading radially from the disk gate as indicated by the thick arrow. When the resin that has reached the cavity 86 is hardened, the molding of the sleeve 37 is completed. The molded sleeve 37 is coupled to each of the collar 35 and the tooth portion 36. Thereby, the gear 22 is completed (refer FIG. 4).

  A pin gate (not shown) may be used instead of the disk gate (not shown). In this case, the plurality of pin gates are arranged in a ring so as to be coaxial with the cavity 86 and face the cavity 86 from above. The molten resin supplied from the nozzle of the injection molding machine reaches each pin gate and is injected into the cavity 86 in the third mold 85 from the pin gate. Since the plurality of pin gates are arranged in a ring shape, when the plurality of pin gates are viewed as a whole, the molten resin is injected into the cavity 86 while spreading radially.

The present invention is not limited to the embodiment described above, and various modifications can be made within the scope of the claims.
For example, the front rib 55 of the front portion 37A of the sleeve 37 extends radially from the front flange 45E around the central axis J as seen from the front side X1 (see FIG. 6), but the second deformation shown in FIG. Like the sleeve 37 of the gear 22 in the example, two adjacent front ribs 55 may intersect so as to draw “X”.

  In the above-described embodiment, in the sleeve 37, the outer peripheral engaging portion 52 is configured by the outer peripheral rib 50 and the outer peripheral groove 51 extending in the axial direction X, and the front engaging portion 57 is the front rib 55 extending in the radial direction Z. And a front groove 56. Instead, like the gear 22 of the third modified example shown in FIG. 16, the outer peripheral engaging portion 52 is configured by a protruding outer peripheral convex portion 90 extending in the radial outer side Z1 and a concave outer peripheral concave portion 91. May be. A plurality of outer peripheral convex portions 90 are provided and are discretely arranged. The adjacent outer peripheral convex portions 90 may be arranged in the axial direction X. The outer circumferential recess 91 exists around each outer circumferential projection 90. Similar to the outer peripheral engagement portion 52, the front engagement portion 57 includes a plurality of protrusion-like front projections 92 extending to the front side X1, and concave front depressions that exist around each front projection 92. 93. The plurality of front protrusions 92 are discretely arranged. The adjacent front projections 92 may be arranged in the radial direction Z.

  In the above-described embodiment, the output shaft 9 is press-fitted into the through hole 30 of the collar 35 of the gear 22 in order to connect the gear 22 to the output shaft 9 so as to be integrally rotatable. Alternatively, serrations may be provided on the inner peripheral surface of the collar 35 and the outer peripheral surface of the output shaft 9 so that the collar 35 and the output shaft 9 are serrated. In the gear 22, the collar 35 may be omitted. In this case, the sleeve 37 is directly connected to the output shaft 9.

In the tooth portion 36, the gear teeth 31 may be formed only on the second portion 42, or may be formed across the first portion 41 and the second portion 42. Further, when the tooth portion 36 is not molded by resin using the first mold 65 or the second mold 70, the tooth portion 36 may be made of metal instead of resin.
Moreover, you may catch each of the above-mentioned front side X1 and back side X2 conversely.

  In the embodiment described above, the gear 22 is used for the speed reducer 20 of the steering device 1, but it can also be used for devices other than the steering device 1.

DESCRIPTION OF SYMBOLS 1 ... Steering device, 2 ... Steering member, 6 ... Steering mechanism, 19 ... Electric motor, 20 ... Reduction gear, 22 ... Gear, 31 ... Gear tooth, 36 ... Tooth part, 37 ... Sleeve, 37A ... Front part, 41 ... 1st part, 42 ... 2nd part, 46 ... outer peripheral part, 48 ... outer peripheral flange, 50 ... outer peripheral rib, 55 ... front rib, X ... axial direction, X1 ... front side, Y ... circumferential direction, Z ... radial direction, Z1 ... radially outward

Claims (4)

A resin-made sleeve formed in a disk shape, provided on the outer peripheral portion, provided on the outer peripheral portion with an outer peripheral rib extending in the axial direction of the sleeve while protruding outward in the radial direction of the sleeve, and the diameter A sleeve having an outer peripheral flange connected to the outer peripheral rib and extending in the circumferential direction of the sleeve while protruding outward in a direction;
A tooth portion that covers at least the outer peripheral portion, is engaged by the outer peripheral rib and the outer peripheral flange, and has gear teeth formed;
Including a gear. The tooth portion integrally includes a first portion that covers the outer peripheral portion and a second portion that covers a front portion on one side in the axial direction of the sleeve,
The gear according to claim 1, further comprising a front rib that is provided on the front portion, protrudes toward the one side, and engages with the second portion.   The gear according to claim 2, wherein the outer peripheral rib and the front rib are connected to each other. An electric motor driven based on steering of the steering member;
A steering device comprising: the gear according to claim 1, and a speed reducer that decelerates the output rotation of the electric motor by the gear and transmits the reduced speed to the steering mechanism.

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