JP4950926B2 - Gear shaft bearing structure - Google Patents

Description

  The present invention relates to a gear shaft bearing structure, and more particularly to a gear shaft bearing structure of a reduction gear mechanism provided in a wiper motor or the like.

As a bearing structure of a gear shaft of a reduction gear mechanism provided in a wiper motor or the like, there is a sliding bearing using a cylindrical bearing member called a plain metal (for example, Patent Document 1).
Japanese Utility Model Publication No. Hei 6-31362

  Like a reduction gear mechanism associated with a wiper motor, if it includes a worm gear and the axis of the output gear shaft extends in the radial direction of the wiper motor perpendicular to the central axis of the wiper motor, the tip of the output gear shaft The tip of the output gear shaft protrudes radially outward from the outer diameter of the yoke so that the attached wiper arm does not interfere with the outer housing (yoke) of the wiper motor, and the axial length of the output gear shaft becomes longer according to the yoke radius.

  Conventionally, such a shaft slide bearing of a gear shaft has the same specification using a long plain metal covering almost the entire length of the shaft length of the gear shaft regardless of the output torque of the wiper motor and the driving load of the wiper system. It has become.

  However, in many cases, the plain metal is an expensive metal material including rare metal such as a baby metal (white metal). From the viewpoint of AV / AE (Value Analysis / Value Engineering) and resource saving, It should be set to the minimum necessary for the output torque and load.

  The problem to be solved by the present invention is that the bearing structure of the gear shaft can be used without changing the bearing structure on the housing side (shaft support member), without increasing the number of parts, regardless of the shaft length of the gear shaft. The member (plain metal) is to be set to the minimum necessary for the output torque and load, and in addition, it can cope with overload.

  In the bearing structure of the gear shaft according to the present invention, a cylindrical bearing member is disposed in a bearing hole formed in the shaft support member, and a gear shaft fixed to the hub portion of the gear is fitted to the bearing member, A cylindrical extending sleeve portion extending from the hub portion toward the bearing member is integrally formed, and the extending sleeve portion is inserted into the bearing hole.

  In the bearing structure of the gear shaft according to the present invention, preferably, the extending sleeve portion is adjacent to the bearing member in the axial direction and loosely fitted to the bearing hole.

  In the bearing structure of the gear shaft according to the present invention, preferably, the loose engagement between the extension sleeve portion and the bearing hole is caused by bending deformation of the gear shaft so that the extension sleeve portion is brought into contact with the inner peripheral surface of the bearing hole. The clearance is set so that the extended sleeve portion comes into contact with the bearing load in an auxiliary manner.

  As a preferred application example, the gear shaft bearing structure according to the present invention is an output gear shaft of a reduction gear mechanism associated with a wiper motor.

  According to the gear shaft bearing structure of the present invention, the cylindrical extension sleeve portion extends from the hub portion to the bearing member arrangement side from the hub portion, and the extension sleeve portion extends into the bearing hole of the bearing member arrangement. Since it is inserted, the axial length of the bearing member can be shortened by the extended shaft length of the extended sleeve portion.

  That is, in this bearing structure, the sliding bearing is composed of a bearing member (plain metal) and an extending sleeve portion, and the bearing member is set to the minimum necessary for the output torque and load. In the case of overload, the load can be handled by the extending sleeve portion in addition to the bearing member.

  Since the extended sleeve portion is integrally formed with the hub portion of the gear, providing the extended sleeve portion does not increase the number of parts.

  Thus, the gear shaft bearing structure according to the present invention can take measures against AV and AE.

  An embodiment in which the gear shaft bearing structure according to the present invention is applied to the output gear shaft bearing structure of a reduction gear mechanism associated with a wiper motor will be described below with reference to FIGS.

  FIG. 1 shows the overall configuration of the wiper drive mechanism. The wiper drive mechanism includes a wiper motor 10 and a reduction gear mechanism 30 attached to the wiper motor 10.

  The wiper motor 10 is constituted by a DC motor, and is constituted by a pair of half-cylindrical permanent magnets in a motor housing (outer housing) 13 including a yoke member 11 and an end member 12 connected to the yoke member 11. The stator 14 has a fixed arrangement, and an armature 15 that can rotate within the stator 14. The armature 15 is inside the stator 14 and integrally has an armature shaft 16 at the center. The armature shaft 16 is rotatably supported by the motor housing 13 by bearing members 17 and 18 provided on the yoke member 11 and the end member 12.

  A commutator 19 is attached to the armature 15, and a power supply brush mechanism 21 including a brush member 20 that is in sliding contact with the commutator 19 is attached to the end member 12.

  The armature shaft 16 is an output shaft of the wiper motor 10, and a tip of the armature shaft 16 is provided integrally with the end member 12 and extends into a gear housing 31 that houses the reduction gear mechanism 30. A worm 16A is formed on the substrate. An intermediate gear shaft 32 is attached to the gear housing 31. A worm wheel 33 that meshes with the worm 16 </ b> A of the armature shaft 16 is rotatably attached to the intermediate gear shaft 32. An intermediate gear 34 is provided integrally with the worm wheel 33. An output gear 35 is engaged with the intermediate gear 34.

  As shown well in FIG. 2, the output gear shaft 37 is connected to the hub portion 36 of the output gear 35 with a serration portion 38 formed at one end (lower end) of the output gear shaft 37. It is fixed with. At the other end (upper end) of the output gear shaft 37 is formed a link plate mounting screw portion 39 to which a link plate (not shown) for transmitting the rotational force of the wiper motor 10 is attached to a wiper arm (not shown).

  The shaft tip of the output gear shaft 37 (link plate mounting screw portion 39) is connected to the motor so that a link plate (not shown) attached to the link plate mounting screw portion 39 of the output gear shaft 37 does not interfere with the motor housing 13 of the wiper motor 10. It is radially outward from the outer diameter of the housing 13. Thereby, the shaft length of the output gear shaft 37 is long according to the radius of the motor housing 13.

  The gear housing 31 is integrally formed with a shaft support cylindrical portion 40 as a shaft support member of the output gear shaft 37 so as to protrude in and out of the housing. The shaft support cylindrical portion 40 has an axial length corresponding to the axial length of the output gear shaft 37 and defines a bearing hole 41 on the inner side.

  A cylindrical bearing member made of sintered metal, that is, a plain metal 42 made of a bearing alloy such as white metal is disposed in the bearing hole 41 in the shaft support cylindrical portion 40. An output gear shaft 37 is rotatably fitted to the plain metal 42. Thus, the output gear shaft 37 is supported by the plain metal 42 so as to be rotatable in a sliding bearing manner from the gear housing 31.

  The output gear 35 is a resin molded product such as polyacetal, and a cylindrical extending sleeve portion 43 that extends from the hub portion 36 toward the plane metal 42 is integrally formed with the hub portion 36.

  The extension sleeve portion 43 surrounds the outer periphery of the output gear shaft 37 on the serration portion 38 side, is inserted into the bearing hole 41 of the shaft support cylindrical portion 40, and is adjacent to the plain metal 42 in the axial direction.

  Here, the inner diameter Da of the plain metal 42 is substantially equal to the outer diameter Db of the output gear shaft 37, and the outer diameter Dc of the plain metal 42 is substantially equal to the inner diameter Dd of the bearing hole 41, so that a normal sliding bearing is configured.

  The extending sleeve portion 43 is a straight cylinder, and the outer diameter De of the extending sleeve portion 43 is slightly smaller than the inner diameter Dd of the bearing hole 41. Thereby, the extending sleeve portion 43 is loosely fitted (gap fitting) with the bearing hole 41 in a form adjacent to the plain metal 42 in the axial direction. In the loose fitting of the extension sleeve portion 43 and the bearing hole 41, when the output gear shaft 37 is overloaded and bending deformation of a predetermined amount or more occurs in the output gear shaft 37, the extension sleeve portion 43 is moved into the bearing hole. A gap t is set between the extending sleeve portion 43 and the bearing hole 41 so that the extending sleeve portion 43 is in contact with the inner peripheral surface of the terminal 41 and is responsible for the load.

  Due to the presence of the above-described extension sleeve portion 43, the plain metal 42 is shorter by the axial length of the extension sleeve portion 43.

  In this bearing structure, the plain bearing is composed of the plain metal 42 and the extending sleeve portion 43, and the plain metal 42 is set to the minimum necessary for the output torque and load, and then, when overloaded. For example, in addition to the plain metal 42, the extended sleeve portion 43 can handle the load.

  That is, at the normal rated load, the plain bearing of the output gear shaft 37 using only the plain metal 42 is established, and for loads exceeding the predetermined value from the wiper system (overload, restraint, etc.) In addition to 42, the extended sleeve portion 43 receives a load.

  As a result, the plane metal 42 can be shortened with the same performance, and the portion where the plane metal 42 is vacated is filled with the extended sleeve portion 43, and excellent AV / AE measures are taken.

  Furthermore, since the extension sleeve portion 43 is integrally formed with the hub portion 36 of the output gear 35 by die casting or resin molding, the provision of the extension sleeve portion 43 also increases the number of parts. Don't be.

It is sectional drawing which shows the whole structure of the wiper drive mechanism to which the bearing structure of the gear shaft by this invention was applied. It is an expanded sectional view showing one embodiment of the bearing structure of a gear shaft by the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Wiper motor 30 Reduction gear mechanism 13 Motor housing 14 Stator 15 Armature 30 Reduction gear mechanism 35 Output gear 36 Hub part 37 Output gear shaft 41 Bearing hole 42 Plain metal 43 Extension sleeve part

Claims (2)

A cylindrical bearing member is disposed in a bearing hole formed in the support member, and a gear shaft fixed to the hub portion of the gear is fitted to the bearing member so that the gear shaft can be rotated by the shaft support member. A supporting bearing structure,
The bearing member is a bearing member responsible for a rated load ,
The hub portion is integrally formed with a cylindrical extending sleeve portion extending from the hub portion toward the bearing member, and the extending sleeve portion is adjacent to the bearing member in the axial direction in the bearing hole. The loose insertion of the extended sleeve portion and the bearing hole is caused by bending deformation of the gear shaft when the gear shaft is overloaded. A gear shaft bearing structure in which a gap is set so that the extending sleeve portion comes into contact with the inner peripheral surface of the bearing hole and the extending sleeve portion bears an auxiliary load . The gear shaft bearing structure according to claim 1, wherein the gear shaft is an output gear shaft of a reduction gear mechanism attached to a wiper motor.

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