JP2013226880A - Reduction gear of electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To firmly fix a flange member of a toothed pulley to a pulley body in an electric power steering device having a reduction gear using a toothed belt, to prevent the toothed belt from falling off from the toothed pulley, and to steer To provide an electric power steering apparatus that is not likely to be unable to assist.
In the speed reducer of the electric power steering device 10, an insertion end 34J of a mounting shaft portion 34A of a flange member 34 inserted into a mounting hole 31H of a pulley body 31 in a toothed pulley 30 is formed in the mounting hole 31H. What is crimped to a locking portion 31J provided on the periphery.
[Selection] Figure 3

Description

  The present invention relates to a reduction device for an electric power steering apparatus.

  As a reduction device of an electric power steering device, as described in Patent Document 1, a rack shaft is supported on a housing so as to be linearly movable, and a drive-side toothed pulley is fixed to a rotating shaft of an electric motor attached to the housing. The driven side toothed pulley is fixed to the ball nut that meshes with the ball screw provided in the shaft, and the rotational force of the driving side toothed pulley is transmitted to the driven side toothed pulley via the toothed belt. .

  In the reduction device of the electric power steering apparatus described in Patent Document 1, the driving-side toothed pulley and the driven-side toothed pulley are fixed on both sides of the pulley body with a flange member having a larger outer diameter than the toothed portion. Yes. The flange member of the toothed pulley regulates the winding position of the toothed belt wound around the tooth portion of the pulley main body and prevents its falling off.

  In addition, the toothed pulley which fixed the flange member to the pulley main body fits the flange member to the pulley main body, and is caulked to prevent it from coming off, as described in Patent Document 2.

JP2007-153300 JP2004-183742

  In the speed reducer of the electric power steering apparatus described in Patent Document 1, the toothed pulley is fitted with a flange member to the pulley body, and is crimped, or press-fitted, screwed, bonded, etc., as described in Patent Document 2. It is fixed with.

  However, the flange member of the toothed pulley is only fixed to the pulley body by caulking or the like. Therefore, when the flange member is detached from the pulley body due to the contact force exerted on the flange member by the toothed belt and the flange member falls off, the toothed belt comes off from the toothed pulley. The rotational force of the electric motor is not transmitted to the rack shaft, and steering assist by the electric motor becomes impossible.

  An object of the present invention is to provide an electric power steering apparatus having a reduction gear using a toothed belt, in which the flange member of the toothed pulley is firmly fixed to the pulley body, and the toothed belt is prevented from falling off from the toothed pulley. It is another object of the present invention to provide an electric power steering device that does not cause the possibility of steering assist being impossible.

  According to the first aspect of the present invention, a rack shaft is supported on a housing so as to be linearly movable, a drive-side toothed pulley is fixed to a rotating shaft of an electric motor attached to the housing, and a ball that meshes with a ball screw provided on the rack shaft. In a reduction device for an electric power steering apparatus in which a driven toothed pulley is fixed to a nut and the rotational force of the driving toothed pulley is transmitted to the driven toothed pulley via the toothed belt, the toothed pulley is connected to the pulley body. A flange member having an outer diameter larger than that of the tooth portion is fixed to one side of the tooth portion on one end side, and the flange member is inserted and attached to a mounting hole formed on the central axis of one end of the pulley body. The mounting shaft portion and a flange portion provided at one end of the mounting shaft portion and projecting in the radial direction, and the insertion end of the mounting shaft portion of the flange member inserted into the mounting hole of the pulley body is within the mounting hole. Around It is obtained as formed by caulking to the retaining portion.

  According to a second aspect of the present invention, in the first aspect of the present invention, the locking portion provided on the inner periphery of the attachment hole of the pulley body is an annular groove.

  The invention according to claim 3 is an electric power steering apparatus including the speed reducer according to claim 1 or 2.

(Claims 1 and 3)
(a) In a toothed pulley around which a toothed belt is wound, the insertion end of the mounting shaft portion of the flange member inserted into the mounting hole of the pulley body is added to the locking portion provided on the inner periphery of the mounting hole. It is tightened. The attachment shaft portion of the flange member is inserted into the attachment hole of the pulley body and attached by, for example, press-fitting, and the insertion end is crimped to the engaging portion on the inner periphery of the attachment hole. Therefore, the flange member of the toothed pulley is firmly fixed to the pulley body. Therefore, in a state where the toothed belt is wound around the toothed pulley, the toothed belt is hooked on the flange member to prevent the toothed belt from falling off, and continues to transmit the rotational force of the electric motor to the rack shaft. The steering assist by the electric motor is not disabled.

  The insertion end of the mounting shaft portion of the flange member may be crimped to the locking portion at a part of the inner periphery of the mounting hole of the pulley body, and the mounting man-hour can be reduced.

  When the attachment shaft portion of the flange member is press-fitted and attached to the attachment hole of the pulley body, the flange member is firmly fixed by the pulley body.

(Claim 2)
(b) Since the engaging portion provided on the inner periphery of the pulley body mounting hole is formed by an annular groove, the insertion end of the mounting shaft portion of the flange member is engaged with the inner periphery of the pulley body mounting hole. The flange member can be firmly fixed by the pulley main body, and can be stably clamped by the portion.

FIG. 1 is a front view showing the entire electric power steering apparatus. FIG. 2 is a cross-sectional view showing the speed reducer. FIG. 3 is an enlarged cross-sectional view showing a main part of the reduction gear. FIG. 4 is an enlarged cross-sectional view showing a main part of the toothed pulley.

  As shown in FIG. 1, the electric power steering apparatus 10 includes a first gear housing 11A and a second gear housing 11B in which the gear housing 11 is divided, and a steering input is input to the gear housing 11 (first gear housing 11A). The shaft 12 is supported, an output shaft (not shown) is connected to the input shaft 12 via a torsion bar 13, a pinion (not shown) is provided on the output shaft, and the rack shaft 14 meshing with the pinion is connected to the gear housing 11. It is supported so that it can move linearly in the left-right direction. A steering torque sensor (not shown) is provided between the input shaft 12 and the output shaft. The steering torque sensor detects the steering torque based on the relative rotational displacement generated between the input shaft 12 and the output shaft due to the elastic torsional deformation of the torsion bar caused by the steering torque applied to the steering wheel.

  The electric power steering apparatus 10 has both end portions of the rack shaft 14 projecting from both sides of the gear housing 11 (first gear housing 11A, second gear housing 11B), and tie rods 15A, 15B are connected to the end portions of the rack shaft 14, The left and right wheels can be steered via tie rods 15A and 15B that are linked to the 14 linear movements.

  The electric power steering device 10 includes an electric motor 20. The electric motor 20 is attached to a bearing housing 21 fixed to the first gear housing 11A, and the serration of the drive shaft 32 of the drive side toothed pulley 30 is coaxially coupled to the serration hole of the rotary shaft 20A of the electric motor 20. ing.

  The electric power steering device 10 has a large-diameter driven-side toothed pulley 40 connected to the small-diameter driving-side toothed pulley 30 via a toothed belt 50 by the rotational force of the driving-side toothed pulley 30 provided by the electric motor 20. Is transmitted to the rack shaft 14 through a power transmission mechanism including a speed reducer.

  As shown in FIGS. 2 and 3, the drive-side toothed pulley 30 has flange members 33 and 34 having a larger outer diameter than the tooth portion 31A on both sides of the tooth portion 31A provided on the drive shaft 32 of the pulley body 31. Prepare. The flange members 33 and 34 on both sides regulate the winding position of the toothed belt 50 wound around the tooth portion 31A and prevent the falling off.

  In the drive side toothed pulley 30, two rolling bearings 35 and 36 are loaded on a drive shaft 32 extending to one side of the tooth portion 31 </ b> A of the pulley body 31, and these bearings 35 and 36 are supported by the above-described bearing housing 21. doing. Here, the bearing 35 is sandwiched between both end surfaces of the outer ring 35 </ b> A by a stepped portion 21 </ b> J near the motor of the small-diameter bearing holding hole of the bearing housing 21 and a retaining ring 35 </ b> C engaged with the bearing holding hole of the bearing housing 21. The position of the inner ring 35B is fixed and the position of the inner ring 35B is fixed and restricted by a retaining ring 35D engaged with the drive shaft 32 at one end surface near the motor. The bearing 36 is positioned between both end surfaces of the outer ring 36 </ b> A between the stepped portion 21 </ b> K near the motor of the large-diameter bearing holding hole of the bearing housing 21 and the retaining ring 36 </ b> C engaged with the bearing holding hole of the bearing housing 21. Has been fixed. The inner ring 36 </ b> B of the bearing 36 sandwiches the flange member 33 between the end surface of the tooth portion 31 </ b> A of the pulley main body 31 near the motor.

  As shown in FIGS. 2 and 3, the driven-side toothed pulley 40 includes a tooth portion 41 </ b> A on the outer periphery of a cup-shaped pulley body 41, and a hollow cylindrical boss 42 at the center of the pulley body 41.

  The electric power steering apparatus 10 is provided with a ball screw 60 on the rack shaft 14, a ball nut 62 that meshes with the ball screw 60 via a ball 61, and a rolling bearing supported on the gear housing 11 (first gear housing 11 </ b> A). A ball nut 62 is rotatably supported by 63. The boss 42 of the driven-side toothed pulley 40 is fixed to the outer periphery of the ball nut 62. Here, the bearing 63 is positioned between both end surfaces of the outer ring 63A by a stepped portion 11J of the bearing holding hole of the first gear housing 11A and a bearing nut 64 screwed into the bearing holding hole of the first gear housing 11A. Regulated and fixed. The boss 42 of the driven-side toothed pulley 40 and the inner ring 63B of the bearing 63 are screwed to the outer periphery of the ball nut 62 at one end step 62J on the outer periphery of the ball nut 62 and the other end on the outer periphery of the ball nut 62. It is clamped and fixed between the locking nuts 65.

  The electric power steering device 10 includes a tooth portion 31A of the pulley body 31 of the driving-side toothed pulley 30 on the electric motor 20 side and a tooth portion 41A of the pulley body 41 of the driven-side toothed pulley 40 on the ball nut 62 side. The toothed belt 50 is wound around, and the rotational force of the driving side toothed pulley 30 is transmitted from the toothed belt 50 to the ball nut 62 via the driven side toothed pulley 40 and then to the rack shaft 14, and the rack shaft 14 is straightened. Move.

Hereinafter, the operation of the electric power steering apparatus 10 will be described.
(1) When the steering torque detected by the steering torque sensor is lower than a predetermined value, the steering assist force is unnecessary and the electric motor 20 is not driven.

  (2) Since the steering assist force is required when the steering torque detected by the steering torque sensor exceeds a predetermined value, the electric motor 20 is driven. The rotational force of the driving-side toothed pulley 30 based on the torque generated by the electric motor 20 is transmitted from the toothed belt 50 to the ball nut 62 via the driven-side toothed pulley 40, and the rack shaft 14 is straightened through the ball screw 60. The steering assist force is moved.

  However, in the electric power steering apparatus 10, the flange member 34 of the driving-side toothed pulley 30 is firmly fixed to the pulley body 31, and the toothed belt 50 is prevented from falling off from the driving-side toothed pulley 30. In order to provide an electric power steering apparatus that does not cause the possibility of steering assist being disabled, the following configuration is provided.

  As shown in FIG. 3, the electric power steering apparatus 10 is configured such that the driving-side toothed pulley 30 is provided on one side of the tooth portion 31 </ b> A provided on the side opposite to the driving shaft 32 of the pulley body 31 ( As described above, the flange member 34 having an outer diameter larger than that of the tooth portion 31A is fixed to the side.

  The flange member 34 is inserted into a mounting hole 31H drilled on the central axis at the end opposite to the drive shaft 32 of the pulley main body 31, and is attached by press fitting or the like, and one end of the mounting shaft portion 34A. And a flange portion 34B projecting in the radial direction. The flange member 34 is, for example, a press-molded product, the attachment shaft portion 34A is formed of a hollow cylinder, and the flange portion 34B is an annular plate (plate thickness b) extended radially outward from one end of the tube of the attachment shaft portion 34A. ). The flange member 34 is attached so that the attachment shaft portion 34A is inserted into the attachment hole 31H of the pulley body 31, and the flange portion 34B is brought into contact with the opening end surface of the attachment hole 31H of the pulley body 31.

  Further, in the drive-side toothed pulley 30, as shown in FIG. 4, the insertion end 34J of the attachment shaft portion 34A of the flange member 34 inserted into the attachment hole 31H of the pulley body 31 has an inner periphery of the attachment hole 31H. And is fastened to a locking portion 31J provided in. That is, in the present embodiment, the mounting shaft portion 34A of the flange member 34 is press-fitted into the mounting hole 31H of the pulley body 31, and then the insertion end 34J is crimped to the locking portion 31J on the inner periphery of the mounting hole 31H. The

  At this time, the locking portion 31J provided in the attachment hole 31H of the pulley body 31 is formed of an annular groove provided in the inner periphery of the attachment hole 31H. Thereby, all or a plurality of portions in the circumferential direction of the cylindrical insertion end 34J of the mounting shaft portion 34A are expanded radially outward within the mounting hole 31H, and the annular groove (the locking portion 31J) is expanded. It is crimped.

According to the present embodiment, the following operational effects can be obtained.
(a) In the driving-side toothed pulley 30 around which the toothed belt 50 is wound, the insertion end 34J of the attachment shaft portion 34A of the flange member 34 inserted into the attachment hole 31H of the pulley body 31 is connected to the attachment hole 31H. It is fastened to a locking portion 31J provided on the inner periphery. The attachment shaft portion 34A of the flange member 34 is inserted into the attachment hole 31H of the pulley body 31 and attached by, for example, press fitting, and the insertion end 34J is caulked to the engaging portion 31J on the inner periphery of the attachment hole 31H. Stopped. Therefore, the flange member 34 of the drive-side toothed pulley 30 is firmly fixed to the pulley body 31. Therefore, in a state where the toothed belt 50 is wound around the driving-side toothed pulley 30, the toothed belt 50 is hooked on the flange member 34 to be prevented from falling off and continues to transmit the rotational force of the electric motor 20 to the rack shaft 14. The steering assist by the electric motor 20 is not disabled.

  The insertion end 34J of the mounting shaft portion 34A of the flange member 34 may be crimped to the locking portion 31J at a part of the inner periphery of the mounting hole 31H of the pulley body 31, and the mounting man-hour can be reduced.

  When the attachment shaft portion 34 </ b> A of the flange member 34 is press-fitted and attached to the attachment hole 31 </ b> H of the pulley body 31, the flange member 34 is firmly fixed to the pulley body 31.

  (b) When the engaging portion 31J provided on the inner periphery of the attachment hole 31H of the pulley body 31 is formed of an annular groove, the insertion end 34J of the attachment shaft portion 34A of the flange member 34 is attached to the pulley body 31. The flange member 34 can be firmly fixed by the pulley body 31 by being stably clamped by the locking portion 31J on the inner periphery of the hole 31H.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention. For example, in the present invention, even if the flange member is fixed to one end side of the pulley body of the driven-side toothed pulley, the flange member is inserted into a mounting hole formed on the central axis of one end of the pulley body. Mounting shaft portion and a flange portion provided at one end of the mounting shaft portion and projecting in the radial direction. The insertion end of the mounting shaft portion of the flange member inserted into the mounting hole of the pulley body is attached to the mounting shaft portion. It may be one that is crimped to a locking portion provided on the inner periphery of the hole.

  The present invention is such that a rack shaft is supported by a housing so as to be linearly movable, a driving-side toothed pulley is fixed to a rotating shaft of an electric motor attached to the housing, and a ball nut engaged with a ball screw provided on the rack shaft is driven. In a reduction device for an electric power steering apparatus in which a toothed pulley is fixed and the rotational force of a driving side toothed pulley is transmitted to a driven side toothed pulley via a toothed belt, the toothed pulley is a tooth on one end side of the pulley body. A flange member having an outer diameter larger than that of the tooth portion is fixed to one side of the portion, and the flange member is inserted into a mounting hole drilled on the central shaft at one end of the pulley body and attached to the mounting shaft portion. A flange portion provided at one end of the mounting shaft portion and projecting in the radial direction, and an insertion end of the mounting shaft portion of the flange member inserted into the mounting hole of the pulley body is provided on the inner periphery of the mounting hole. Clamping the locking part It is fit. As a result, in the electric power steering apparatus having the reduction gear using the toothed belt, the flange member of the toothed pulley is firmly fixed to the pulley body, and the toothed belt is prevented from falling off from the toothed pulley. It is possible to provide an electric power steering apparatus that is not likely to be unable to assist.

DESCRIPTION OF SYMBOLS 10 Electric power steering apparatus 11 Housing 14 Rack shaft 20 Electric motor 20A Rotating shaft 30 Drive side toothed pulley 31 Pulley body 31A Tooth portion 31H Mounting hole 31J Locking portion 32 Drive shaft 34 Flange member 34A Mounting shaft portion 34B Flange portion 34J Stop (annular groove)
40 Driven side toothed pulley 50 Toothed belt

Claims (3)

The rack shaft is supported by the housing so that it can move linearly,
Fix the drive side toothed pulley to the rotating shaft of the electric motor attached to the housing,
Fix the driven side pulley with a ball nut that meshes with the ball screw provided on the rack shaft,
In the reduction device of the electric power steering device in which the rotational force of the driving side toothed pulley is transmitted to the driven side toothed pulley via the toothed belt,
The toothed pulley is formed by fixing a flange member having a larger outer diameter than the tooth part on one side of the tooth part on one end side of the pulley body,
The flange member includes an attachment shaft portion that is inserted and attached to an attachment hole formed on the central shaft at one end of the pulley body, and a flange portion that is provided at one end of the attachment shaft portion and projects in the radial direction.
Deceleration of an electric power steering device characterized in that an insertion end of a mounting shaft portion of a flange member inserted in a mounting hole of a pulley body is crimped by a locking portion provided on an inner periphery of the mounting hole. apparatus.   The speed reducer for an electric power steering apparatus according to claim 1, wherein the engaging portion provided on the inner periphery of the attachment hole of the pulley body is formed of an annular groove.   An electric power steering apparatus comprising the speed reducer according to claim 1.

Images