JP2012153270A - Electric power steering device and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power steering device configured to support a driving rotary body by a first bearing mechanism and a second bearing mechanism, and having flexibility in selecting the structure of the driving rotary body, and to provide a method for manufacturing the same.SOLUTION: The electric power steering device is provided with an electric motor 21 assisting reciprocation of a steering shaft, a driving pulley 41 attached to an output shaft 21A of the electric motor 21 and a housing 30 to which the electric motor 21 is mounted. The first bearing mechanism 50 is provided in a first mounting part 42 of the driving pulley 41, and the second bearing mechanism 70 is provided in a second mounting part 43 of the driving pulley 41.

Description

  The present invention relates to an electric motor that assists linear motion of a steered shaft, a ball screw device that converts rotation of the electric motor into linear motion, a winding transmission device that transmits rotation of the electric motor to the ball screw device, The present invention relates to an electric power steering apparatus including a first bearing mechanism and a second bearing mechanism that support a driving rotating body of a hanging transmission, and a method for manufacturing the same.

As the electric power steering device, one described in Patent Document 1 is known.
In this type of electric power steering apparatus, after the rotation of the output shaft of the electric motor is transmitted to the ball screw device via the winding transmission device, the rotation of the output shaft is converted into linear motion by this device.

With reference to FIG. 9, the structure of the conventional winding transmission apparatus 100 is demonstrated.
The winding transmission device 100 includes a driving pulley 110 attached to the output shaft 211 of the electric motor 210, a driven pulley 120 attached to the ball screw device 220, and a belt 130 connecting the driving pulley 110 and the driven pulley 120. Is provided.

  The drive pulley 110 is provided with a first pulley portion 111 to which an output shaft 211 is attached and a second pulley portion 112 around which a belt 130 is wound. The second pulley portion 112 is provided with a winding portion 113 around which the belt 130 is wound and a support portion 114 provided on the opposite side of the first pulley portion 111 with respect to the winding portion 113 in the axial direction. It has been. A first ball bearing 140 is attached to the first pulley portion 111. A second ball bearing 150 is attached to the support portion 114 of the second pulley portion 112.

Japanese Patent No. 4447138

  By the way, in the said winding transmission apparatus 100, since the structure which supports the support part 114 of the 1st pulley part 111 and the 2nd pulley part 112 with the 1st ball bearing 140 and the 2nd ball bearing 150 is employ | adopted, respectively. A drive pulley having a structure in which the support portion 114 is omitted cannot be used.

  For this reason, when manufacturing an electric power steering device, it is necessary to select a drive pulley having a structure having a support portion 114 as the drive pulley 110. That is, the degree of freedom in selecting the structure of the drive pulley is low.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a configuration in which a drive rotator is supported by a first bearing mechanism and a second bearing mechanism, and further to select a structure of the drive rotator. An object is to provide an electric power steering apparatus having a high degree of freedom and a method for manufacturing the same.

  Means for achieving the above object will be described. In the following description, a drive rotator around which an end portion of the second mounting portion is wound in the axial direction is referred to as an A-type drive rotator. In addition, a drive rotator in which the rotary transmission body is wound around a portion closer to the first attachment portion than the end portion of the second attachment portion in the axial direction is referred to as a B-type drive rotator.

  (1) The invention described in claim 1 is directed to an electric motor that assists linear motion of the steered shaft, a ball screw device that converts rotation of the electric motor into linear motion, and rotation of the electric motor to the ball screw. A winding transmission device that transmits to the device, a first bearing mechanism and a second bearing mechanism that support a driving rotating body of the winding transmission device, the driving rotating body attached to the electric motor, and the ball In the electric power steering apparatus in which the driven rotator attached to the screw device, the drive rotator and the rotation transmission member wound around the driven rotator are provided in the winding transmission device, the drive rotator And a portion including one end portion in the axial direction of the drive rotating body as a first attachment portion to which the output shaft of the electric motor is attached, A portion different from the first attachment portion in the drive rotator, and a portion including the other end portion in the axial direction of the drive rotator as the second attachment portion is wound around the rotation transmission body, The first mounting portion is supported by the first bearing mechanism, the second mounting portion is supported by the second bearing mechanism, and the second bearing mechanism is supported by the second mounting portion. The gist is that the second mounting portion is supported inside.

  According to the above invention, since the second bearing mechanism for supporting the mounting portion is provided inside the second mounting portion, either the A-type driving rotator or the B-type driving rotator is used in manufacturing the electric power steering device. Selection is also allowed. That is, it is possible to provide an electric power steering device with a high degree of freedom in selecting the structure of the drive rotor.

  (2) The invention according to claim 2 is the electric power steering device according to claim 1, wherein a housing for housing the winding transmission device is provided, and the first bearing mechanism has the drive. A bearing for supporting the first mounting portion of the rotating body; and a spacer for restricting movement of the bearing relative to the housing between the housing and the bearing; and A shaft that is inserted into the second mounting portion and supports the second mounting portion is provided. The shaft is fixed to the housing and a shaft portion that is inserted into the driving rotating body. A hole formed in the spacer and into which the bearing is fitted is defined as a bearing fitting hole, and the center line of the bearing fitting hole is opposite to the center line of the spacer. The center line of the shaft portion is decentered with respect to the center line of the head, the center line of the output shaft of the electric motor, the center line of the drive rotor, and the center line of the shaft And the center line of the bearing fitting hole and the center line of the head are the same.

  According to the above invention, the center line of the bearing fitting hole is eccentric with respect to the center line of the spacer, the center line of the shaft portion of the shaft is eccentric with respect to the center line of the head, and the output shaft of the electric motor The center line of the drive, the center line of the drive rotator, and the center line of the shaft match, and the center line of the bearing fitting hole matches the center line of the head. The insertion hole and the shaft shaft revolve around the centerline of the spacer and the centerline of the shaft head. At this time, since the position of the center line of the shaft portion of the shaft with respect to the center line of the driven rotator is changed, the distance between the rotation center of the driven rotator and the rotation center of the drive rotator is also changed.

  For this reason, in the manufacturing process of the electric power steering device, the distance between the drive rotator and the driven rotator is obtained by rotating the spacer and the shaft after the housing, the winding transmission device, the first bearing mechanism and the second bearing mechanism are combined with each other. By changing, the tension of the rotary transmission can be adjusted.

  (3) According to a third aspect of the present invention, in the electric power steering apparatus according to the first or second aspect, a housing for housing the winding transmission device is provided, and the second bearing mechanism includes: A shaft inserted into the second mounting portion and supporting the second mounting portion is provided; the shaft is fixed to the housing; and the second bearing mechanism includes: The gist is that a slide bearing for supporting the shaft is provided between the shaft and the drive rotor.

  (4) According to a fourth aspect of the present invention, in the electric power steering device according to any one of the first to third aspects, the other end portion of the second mounting portion of the drive rotating body is at the other end. The gist is that the rotating transmission is wound around.

  According to the above invention, since the rotation transmission body is wound around the end of the second mounting portion of the drive rotator, that is, the A-type drive rotator is adopted as the drive rotator, the drive rotator As compared with the case where a B-type drive rotator is employed, the drive rotator can be made smaller in the axial direction.

  (5) The invention according to claim 5 is the electric power steering apparatus according to claim 4, wherein the shaft includes a shaft portion inserted into a second mounting portion of the drive rotating body, and the housing. A head fixed to the head, the head is provided outside the housing, and a portion of the housing corresponding to the head as a head fixing portion. The gist is that the portion fixing portion and the second mounting portion of the drive rotating body are adjacent to each other via a gap.

  According to the above invention, since the head portion of the shaft is provided outside the housing, the distance between the drive rotating body and the head fixing portion of the housing is compared with the case where the head portion is provided inside the housing. Can be narrowed.

(6) The invention according to claim 6 is the method for manufacturing the electric power steering apparatus according to claim 5, wherein the housing, the winding transmission device, the first bearing mechanism, and the second bearing mechanism are combined with each other. Assembling the assembled assembly into an assembly that satisfies the following conditions (a) to (e):
(A) “The bearing is attached to the first attachment portion of the drive rotating body”
(B) “The spacer is attached between the housing and the bearing”
(C) “The spacer can be rotated with respect to the housing”
(D) “The shaft portion of the shaft is inserted into the second mounting portion of the drive rotor”
(E) “The shaft can rotate relative to the housing”
After the step A, the step B for adjusting the tension of the rotary transmission of the assembly, the step C for fixing the head of the shaft to the housing after the step B, and the assembly after the step C to the assembly A step D for fixing the electric motor. In the step B, the drive rotor, the bearing, the spacer, and the center of the shaft and the center line of the bearing fitting hole of the spacer are used as rotation centers. The distance between the rotation center of the drive rotator and the rotation center of the driven rotator is changed by integrally rotating the shaft, and the tension of the rotary transmission body is set within a predetermined range by changing the rotation center. The gist is to make adjustments.

  According to the above invention, in order to make the tension of the rotary transmission body within the predetermined range in the step B, that is, before the electric motor is attached to the housing, the tension of the rotary transmission body is adjusted. Compared with the case where the tension of the rotary transmission body is adjusted after being attached to, the work of adjusting the tension of the rotary transmission body can be easily performed.

  According to the present invention, there is provided an electric power steering device having a configuration in which a drive rotator is supported by a first bearing mechanism and a second bearing mechanism, and a high degree of freedom in selecting a structure of the drive rotator, and a method for manufacturing the same. Can be provided.

The front view which shows the whole structure about one Embodiment of the electric power steering apparatus of this invention. The schematic diagram which shows typically the cross-sectional structure of a winding transmission about the electric power steering apparatus of the embodiment. Sectional drawing which shows the cross-sectional structure about the electric power steering apparatus of the embodiment. Sectional drawing which shows the cross-section structure of a winding transmission device and its periphery about the electric power steering apparatus of the embodiment. Sectional drawing which shows the cross-section of the state which decomposed | disassembled the winding transmission about the electric power steering apparatus of the embodiment. The schematic diagram which shows typically the positional relationship of a drive pulley and a driven pulley about the electric power steering apparatus of the embodiment. The flowchart which shows the manufacturing process about the electric power steering apparatus of the embodiment. Sectional drawing which shows the sectional structure of a winding transmission device and its periphery about other embodiment of the electric power steering apparatus of this invention. Sectional drawing which shows the sectional structure of the winding transmission device and its periphery about the conventional electric power steering apparatus.

An embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the electric power steering apparatus 1 steers a steering angle transmission mechanism 10 that transmits the rotation of the steering to the steered wheels and a force that assists the operation of the steering (hereinafter referred to as “assist force”). An assist device 20 applied to the shaft 13 and a housing 30 that accommodates an intermediate portion of the steered shaft 13 are provided. Hereinafter, in the axial direction of the steered shaft 13, the direction from the left end 13A to the right end 13B is referred to as “right”, and the direction from the right end 13B to the left end 13A is referred to as “left”.

  The steering angle transmission mechanism 10 includes a steering shaft 11 that rotates together with the steering, a rack and pinion mechanism 12 that converts the rotation of the steering shaft 11 into a linear motion, and a shaft that moves in the axial direction as the rack and pinion mechanism 12 operates. A rudder shaft 13 is provided.

  The assist device 20 includes an electric motor 21 as a drive source, a ball screw device 22 that converts the rotation of the electric motor 21 into a linear motion and transmits the linear motion to the steered shaft 13, and a winding that decelerates the rotation of the electric motor 21. A hanging transmission 40 is provided.

  The housing 30 includes a first housing 31 and a second housing 34. The left end portion 13 </ b> A and the right end portion 13 </ b> B of the steered shaft 13 protrude from the housing 30.

  The first housing 31 is provided with a cylindrical first main body 32. A first enlarged diameter portion 33 is provided at the right end portion of the first main body portion 32. The outer diameter of the first enlarged diameter portion 33 is larger than the outer diameter of the first main body portion 32. The electric motor 21 is attached to the first enlarged diameter portion 33 by a bolt 23. The electric motor 21 is provided so that the output shaft 21 </ b> A is parallel to the steered shaft 13. A rack and pinion mechanism 12 is provided at the left end of the first main body 32.

  The second housing 34 is provided with a cylindrical second main body portion 35. A second enlarged diameter portion 36 is provided on the left side of the second main body portion 35. A reduced diameter portion 37 is provided on the right side of the second main body portion 35. The outer diameter of the second enlarged diameter portion 36 is larger than the outer diameter of the second main body portion 35. The outer diameter of the reduced diameter portion 37 is smaller than the outer diameter of the second main body portion 35. The second enlarged diameter portion 36 of the second housing 34 corresponds to a “housing head fixing portion”.

The operation of the electric power steering apparatus 1 will be described.
When the driver rotates the steering, the steering shaft 11 rotates together with the steering. The rotation of the steering shaft 11 is converted into a linear motion by the rack and pinion mechanism 12. The steered shaft 13 is moved in the axial direction by the force transmitted from the rack and pinion mechanism 12. And the steering angle of a steered wheel is changed with the movement to the axial direction of the steered shaft 13. FIG. At this time, the torque of the electric motor 21 is applied to the steered shaft 13 through the ball screw device 22 as an assist force.

With reference to FIG. 2, the outline | summary of the support structure of the winding transmission 40 is demonstrated.
In the winding transmission device 40, a drive pulley 41 that rotates integrally with the output shaft 21 </ b> A of the electric motor 21, a driven pulley 46 that rotates integrally with the ball screw device 22, and the rotation of the drive pulley 41 are transmitted to the driven pulley 46. Belt 47 is provided. The drive pulley 41 corresponds to a “drive rotator”. The driven pulley 46 corresponds to a “driven rotor”. The belt 47 corresponds to a “rotary transmission”.

  As the driving pulley 41 and the driven pulley 46, a toothed pulley is used. The belt 47 is a toothed belt that meshes with the teeth of the drive pulley 41 and the driven pulley 46.

  The drive pulley 41 is provided with a cylindrical first attachment portion 42 into which the output shaft 21A of the electric motor 21 is inserted, and a cylindrical second attachment portion 43 around which a belt 47 is wound. The first mounting portion 42 is provided with a first bearing mechanism 50 that supports the mounting portion 42 in a state that allows rotation with respect to the housing 30. The second mounting portion 43 is provided with a second bearing mechanism 70 that supports the mounting portion 43 in a state that allows rotation with respect to the housing 30. The first attachment portion 42 and the second attachment portion 43 are provided as portions that are adjacent to each other in the axial direction and are continuous with each other.

  The first bearing mechanism 50 includes a ball bearing 60 that supports the first mounting portion 42 of the drive pulley 41, a spacer 51 that supports the ball bearing 60, and a C-ring 56 that fixes the spacer 51 to the second housing 34. Is provided.

  The second bearing mechanism 70 includes a sliding bearing 71 that rotates integrally with the second mounting portion 43 of the drive pulley 41, an eccentric shaft 72 that supports the second mounting portion 43 via the sliding bearing 71, and an eccentric shaft 72. And a bolt 78 that fixes the second enlarged diameter portion 36 of the housing 30 to the second enlarged diameter portion 36 of the housing 30. The eccentric shaft 72 corresponds to “the shaft of the second bearing mechanism”.

  The eccentric shaft 72 is provided with a shaft portion 73 inserted into the slide bearing 71 and a head portion 74 fixed to the housing 30 with a bolt 78. The shaft portion 73 slides with respect to the inner peripheral surface of the slide bearing 71.

  In the assist device 20 (see FIG. 1), the adjustment mechanism for changing the distance between the rotation center of the drive pulley 41 and the rotation center of the driven pulley 46, that is, the adjustment mechanism for changing the tension of the belt 47 is the first. The bearing mechanism 50 and the second bearing mechanism 70 are configured.

  The adjustment mechanism has a function of changing the position of the rotation center of the drive pulley 41 relative to the rotation center of the driven pulley 46 by rotating the spacer 51 and the eccentric shaft 72 with respect to the housing 30. When the electric power steering apparatus 1 is completed, the spacer 51 and the eccentric shaft 72 are fixed to the housing 30. Therefore, when the tension of the belt 47 is adjusted after the apparatus 1 is completed, The fixing of the spacer 51 and the eccentric shaft 72 is released.

  In the winding transmission device 40, when the distance between the rotation center of the drive pulley 41 and the rotation center of the driven pulley 46 increases due to the rotation of the spacer 51 and the eccentric shaft 72 with respect to the housing 30, the tension of the belt 47 is unnecessarily large. Also grows. On the other hand, when the distance between the rotation center of the driving pulley 41 and the rotation center of the driven pulley 46 is reduced by the rotation of the spacer 51 and the eccentric shaft 72 with respect to the housing 30, the tension of the belt 47 is also reduced.

  A detailed configuration of the assist device 20 will be described with reference to FIG. Hereinafter, in the radial direction of the output shaft 21A of the electric motor 21, a direction approaching the rotation center of the output shaft 21A is referred to as “inward”, and a direction away from the rotation center of the output shaft 21A is referred to as “outward”.

  The first enlarged diameter portion 33 of the first housing 31 is provided with a first through hole 33A into which the output shaft 21A of the electric motor 21 is inserted, and a flange 33C protruding outward in the radial direction of the output shaft 21A. ing. The right end surface of the main body portion 21 </ b> B of the electric motor 21 is in contact with the left end surface of the first enlarged diameter portion 33.

  The first through hole 33A is provided with an annular groove 33B that is recessed outward in the radial direction of the output shaft 21A. A bolt insertion hole 33D is provided in the flange 33C. The diameter of the bolt insertion hole 33 </ b> D is larger than the outer diameter of the shaft portion of the bolt 23. The bolt 23 is fastened to the main body portion 21B via the bolt insertion hole 33D.

  The first attachment portion 42 is a part of the drive pulley 41 and is configured as a portion to which the output shaft 21 </ b> A of the electric motor 21 is attached and which includes the left end portion of the drive pulley 41. Further, the second attachment portion 43 is a part different from the first attachment portion 42 in the drive pulley 41, and is configured as a portion including the right end portion of the drive pulley 41 while the belt 47 is wound around. .

  The first attachment portion 42 is formed with a first insertion hole 44 into which the output shaft 21A is inserted. The first insertion hole 44 is formed from the left end face of the first attachment portion 42 to the intermediate portion in the axial direction. Serrations are formed on each of the inner peripheral surface of the first insertion hole 44 and the outer peripheral surface of the output shaft 21A. The serration of the first insertion hole 44 and the serration of the output shaft 21A are engaged with each other.

  The second attachment portion 43 is provided with a second insertion hole 45 into which the second bearing mechanism 70 is inserted. The second insertion hole 45 is formed from the right end surface of the second attachment portion 43 to the intermediate portion in the axial direction.

With reference to FIG. 4, the detailed structure of each bearing mechanism 50 and 70 is demonstrated.
The ball bearing 60 is provided with an inner ring 61 attached to the first attachment portion 42, an outer ring 62 attached to the spacer 51, and a plurality of rolling elements 63 provided between the inner ring 61 and the outer ring 62. Yes.

  The spacer 51 includes a cylindrical support portion 52 that supports the outer ring 62, a cylindrical restriction portion 53 that restricts the movement of the outer ring 62 in the axial direction, and protrudes radially outward at the left end of the support portion 52. A flange 54 is provided.

  A bearing fitting hole 55 into which the outer ring 62 is fitted is formed in the support portion 52. The restricting portion 53 is located radially inward of the first through hole 33 </ b> A and protrudes to the left of the left end surface of the first enlarged diameter portion 33. The left end of the restricting portion 53 is fitted in the hole of the main body portion 21 </ b> B of the electric motor 21. The flange 54 is sandwiched between the C ring 56 and the first enlarged diameter portion 33. The C ring 56 is fitted in the annular groove 33 </ b> B of the second housing 34.

  The spacer 51 has a first diameter expansion due to a frictional force between the flange 54 and the first diameter-expanded portion 33, a frictional force between the flange 54 and the C-ring 56, and a frictional force between the support portion 52 and the first diameter-expanded portion 33. The rotation with respect to the portion 33 is restricted.

  The shaft portion 73 of the eccentric shaft 72 is inserted into the second through hole 36 </ b> A provided in the second enlarged diameter portion 36 of the second housing 34. In the head 74 of the eccentric shaft 72, the two through holes 75 into which the shaft portions of the bolts 78 are inserted, the pair of plane portions 76, and the second through holes 36A of the second enlarged diameter portion 36 are fitted into the contraction. A diameter portion 77 is provided. The inner diameter of the through hole 75 of the eccentric shaft 72 is larger than the diameter of the bolt 78.

With reference to FIG. 5, the positional relationship of the center lines of the output shaft 21A, the drive pulley 41, the spacer 51, and the second bearing mechanism 70 of the electric motor 21 will be described.
In the assist device 20 (see FIG. 3), the center line as the rotation center of the spacer 51, the center line of the first through hole 33 </ b> A of the first housing 31, and the center line of the second through hole 36 </ b> A of the second housing 34. And the center line as the rotation center of the eccentric shaft 72 coincide with each other. Hereinafter, the center line of the spacer 51, the center line of the first through hole 33A of the first housing 31, the center line of the second through hole 36A of the second housing 34, and the center line of the eccentric shaft 72 are collectively shown. This is referred to as “reference center line J2.”

  Further, the center line as the rotation center of the output shaft 21 </ b> A of the electric motor 21, the center line as the rotation center of the drive pulley 41, the center line as the rotation center of the slide bearing 71, and the shaft portion 73 of the eccentric shaft 72. The center line, the center line of the bearing fitting hole 55 of the spacer 51, the center line of the restricting portion 53 of the spacer 51, and the center line of the main body portion 21B of the electric motor 21 coincide with each other. In the following, the center line of the output shaft 21A of the electric motor 21, the center line of the drive pulley 41, the center line of the slide bearing 71, the center line of the shaft portion 73 of the eccentric shaft 72, and the bearing fitting hole of the spacer 51 The center line 55, the center line of the restricting portion 53 of the spacer 51, and the center line of the main body 21B of the electric motor 21 are collectively referred to as an “eccentric center line J1”.

  In the assist device 20, since the eccentric center line J1 is eccentric with respect to the reference center line J2, when the spacer 51 and the eccentric shaft 72 are rotated with respect to the housing 30, the eccentric center line J1 becomes the reference center line J2. Revolve around. That is, the eccentric amount D1 of the center line of the output shaft 21A with respect to the reference center line J2, the eccentric amount D2 of the center line of the drive pulley 41 with respect to the reference center line J2, and the eccentric amount of the center line of the slide bearing 71 with respect to the reference center line J2. D3, the eccentric amount D4 of the center line of the shaft portion 73 with respect to the reference center line J2, and the eccentric amount D5 of the center line of the bearing fitting hole 55 of the spacer 51 with respect to the reference center line J2 are the same. For this reason, the drive pulley 41 revolves around the reference center line J2 without being inclined with respect to the axial direction.

  Details of the tension adjustment method of the belt 47 will be described with reference to FIG. Hereinafter, the distance between the eccentric center line J1 and the rotation center line J3 of the driven pulley 46 is referred to as “inter-pulley distance”. Further, the position of the eccentric center line J1 with respect to the reference center line J2 shown in FIG. Further, the distance between the pulleys at the reference position KP is defined as “reference distance KD”, and the tension of the belt 47 at that time is defined as “reference tension KT”.

  When the spacer 51 and the eccentric shaft 72 (see FIG. 4) are rotated clockwise in a state where the eccentric center line J1 is at the reference position KP, the eccentric center line J1 rotates clockwise with respect to the reference center line J2. . Accordingly, since the rotation center of the drive pulley 41 is separated from the rotation center of the driven pulley 46, the distance between the pulleys becomes larger than the reference distance KD. For this reason, the tension of the belt 47 becomes larger than the reference tension KT. As shown in FIG. 6B, when the eccentric center line J1 is at a position farthest from the rotation center line J3, the distance between the pulleys becomes the maximum distance Dmax. For this reason, the tension of the belt 47 is maximized within the adjustable range of the tension.

  When the spacer 51 and the eccentric shaft 72 are rotated counterclockwise while the eccentric center line J1 is at the reference position KP, the eccentric center line J1 rotates counterclockwise with respect to the reference center line J2. Accordingly, since the rotation center of the drive pulley 41 approaches the rotation center of the driven pulley 46, the distance between the pulleys becomes smaller than the reference distance KD. For this reason, the tension of the belt 47 becomes smaller than the reference tension KT. As shown in FIG. 6C, when the eccentric center line J1 is located closest to the rotation center line J3, the distance between the pulleys becomes the minimum distance Dmin. For this reason, the tension of the belt 47 is minimized within the adjustable range of the tension.

A manufacturing process of the device 1 will be described with reference to FIGS. 3, 4, and 7.
In step S1, an assembly that satisfies the following conditions (a) to (e) is obtained by combining the second housing 34, the ball screw device 22, the winding transmission device 40, the first bearing mechanism 50, and the second bearing mechanism 70. assemble. Step S1 corresponds to “Step A”.

(A) “Ball bearing 60 is attached to first attachment portion 42 of drive pulley 41”
(B) “Spacer 51 is attached between second housing 34 and ball bearing 60”
(C) “The spacer 51 can rotate with respect to the second housing 34”.
(D) “The shaft portion 73 of the eccentric shaft 72 is inserted into the second mounting portion 43 of the pulley”
(E) “Eccentric shaft 72 can rotate relative to second housing 34”
The above-described assembly corresponds to an assembly in which the electric motor 21, the bolt 23, the C ring 56 and the bolt 78 are omitted from the electric power steering apparatus 1 shown in FIGS.

  In step S2, an operation of adjusting the tension of the belt 47 of the assembly is performed after step S1. Specifically, the drive pulley 41, the ball bearing 60, the spacer 51, and the eccentric shaft 72 are rotated integrally with the center line of the head 74 of the eccentric shaft 72 and the bearing insertion hole 55 of the spacer 51 as the rotation center. Thus, the distance between the rotation center of the drive pulley 41 and the rotation center of the driven pulley 46, that is, the distance between the pulleys, which is the distance between the eccentric center line J1 and the rotation center line J3, is changed. Then, when the tension of the belt 47 measured by the tension meter is within the target range, the change of the distance between the pulleys is finished. Step S2 corresponds to “Step B”.

  In step S3, after step S2, the head portion 74 of the eccentric shaft 72 is fixed to the second enlarged diameter portion 36 of the second housing 34 with the bolt 78. Further, the spacer 51 is fixed to the first enlarged diameter portion 33 of the first housing 31 by fitting the C ring 56 into the annular groove 33 </ b> B of the first housing 31. Step S3 corresponds to “Step C”.

  In step S <b> 4, after step S <b> 3, the output shaft 21 </ b> A of the electric motor 21 is inserted into the first mounting portion 42 of the drive pulley 41, and the main body portion 21 </ b> B of the electric motor 21 is tightened by the bolt 23 with the first diameter increase of the first housing 31. It fixes to the part 33. Step S4 corresponds to “Step D”.

(Effect of embodiment)
According to the electric power steering apparatus 1 of the present embodiment, the following effects can be obtained.
(1) In the electric power steering apparatus 1, a configuration in which the second bearing mechanism 70 is provided inside the second attachment portion 43 of the drive pulley 41 is employed. In this configuration, for example, the drive pulley 80 shown in FIG. 8, that is, the drive in which the belt 47 is wound around the first attachment portion 81 side of the second attachment portion 82 of the drive pulley 80 rather than the right end in the axial direction. The present invention can also be applied to an electric power steering apparatus having a pulley 80. That is, it is possible to provide an electric power steering device with a high degree of freedom in selecting the structure of the drive pulley.

  (2) In the electric power steering apparatus 1, the second bearing mechanism 70 is provided in the second insertion hole 45 of the second mounting portion 43 of the drive pulley 41. According to this configuration, for example, the drive pulley 41 can be made smaller in the axial direction than the drive pulley 110 shown in FIG.

  (3) In the electric power steering apparatus 1, the head portion 74 of the eccentric shaft 72 is provided outside the second diameter-expanded portion 36 of the second housing 34. According to this configuration, the distance between the drive pulley 41 and the second enlarged diameter portion 36 can be reduced as compared with a configuration in which the head 74 is provided inside the second enlarged diameter portion 36.

  (4) In the electric power steering apparatus 1, the eccentric pulley centerline J1 revolves around the reference centerline J2, so that the drive pulley 41 revolves around the reference centerline J2. Further, as the drive pulley 41 revolves, the distance between the drive pulley 41 and the driven pulley 46 changes. According to this configuration, in the manufacturing process of the electric power steering apparatus 1, the tension of the belt 47 can be adjusted by revolving the spacer 51 and the eccentric shaft 72 around the reference center line J2 after assembling the assembly.

  (5) In the electric power steering apparatus 1, both the spacer 51 and the eccentric shaft 72 revolve around the reference center line J2. According to this configuration, when the drive pulley 41 revolves around the reference center, the drive pulley 41 can be prevented from being inclined in the axial direction due to the tension of the belt 47.

  (6) In the method for manufacturing the electric power steering apparatus 1, the tension is adjusted so that the tension of the belt 47 is within the target range by revolving the spacer 51 and the eccentric shaft 72, and then the output shaft 21A of the electric motor 21 is adjusted. Is attached to the drive pulley 41. For this reason, compared with the case where the tension of the belt 47 is adjusted after the electric motor 21 is attached to the drive pulley 41, the work of adjusting the tension of the belt 47 can be easily performed.

  (7) In the electric power steering device 1, the serration of the output shaft 21 </ b> A of the electric motor 21 and the serration of the first attachment portion 42 of the drive pulley 41 are engaged with each other. That is, the drive pulley 41 and the output shaft 21A are combined in a state where the attachment to the output shaft 21A and the removal from the output shaft 21A are possible. According to this configuration, it is possible to remove the electric motor 21 from the drive pulley 41 by removing the bolt 23 from the housing 30, so that the electric motor 21 and the drive pulley 41 can be replaced separately.

  (8) In the electric power steering apparatus 1, the flat portion 76 is provided on the head 74 of the eccentric shaft 72. According to this configuration, since the eccentric shaft 72 can be revolved while the operator hooks his / her finger on the flat portion 76, the operator can easily rotate the head 74. For this reason, workability when adjusting the tension of the belt 47 is further improved.

  (9) In the electric power steering apparatus 1, the restricting portion 53 of the spacer 51 is radially separated from the first through hole 33 </ b> A of the first enlarged diameter portion 33 and from the left end surface of the first enlarged diameter portion 33. Also protrudes to the left. According to this configuration, since the operator can easily grip the spacer 51, the tension of the belt 47 can be easily adjusted.

  (10) In the electric power steering apparatus 1, the reduced diameter portion 77 of the head 74 of the eccentric shaft 72 is fitted in the second through hole 36 </ b> A of the second expanded diameter portion 36. According to this structure, it can suppress that the center line of the head 74 shifts | deviates with respect to the center line of 36 A of 2nd through-holes.

(Other embodiments)
The specific configuration of the electric power steering apparatus of the present invention is not limited to the contents of the above-described embodiment, and can be modified as follows, for example. Further, the following modified examples are not applied only to the above embodiment, and different modified examples can be implemented in combination with each other.

  In the above embodiment, the C ring 56 is used to fix the spacer 51 to the first enlarged diameter portion 33 of the first housing 31, but the structure for fixing the spacer 51 to the first enlarged diameter portion 33 is It is not limited to this. For example, a fixing nut can be used in place of the C-ring 56. In this case, a female screw is formed in the portion where the first through-hole 33A is formed in the first enlarged diameter portion 33 instead of the annular groove 33B.

  In the above embodiment, the spacer 51 can be omitted. In this case, the outer ring 62 of the ball bearing 60 is attached to the first enlarged diameter portion 33. In the manufacturing process of the electric power steering apparatus 1, the tension of the belt 47 can be adjusted by rotating the eccentric shaft 72.

  In the above embodiment, the center line of the shaft portion 73 of the eccentric shaft 72 and the center line of the slide bearing 71 can be matched. In this case, in the manufacturing process of the electric power steering apparatus 1, the tension of the belt 47 can be adjusted by rotating the spacer 51.

  In the above embodiment, the ball bearing 60 is used as the bearing of the first bearing mechanism 50, but other rolling bearings such as roller bearings may be used instead of the ball bearing 60. In addition, a sliding bearing can be used instead of the rolling bearing.

  In the above embodiment, the slide bearing 71 is used as the bearing of the second bearing mechanism 70, but a rolling bearing may be used instead of the slide bearing 71. In this case, the outer ring of the rolling bearing is attached to the second insertion hole 45 in place of the slide bearing 71 attached to the second insertion hole 45 of the drive pulley 41. The second housing 34 is provided with a shaft that is fixed to the inner ring of the rolling bearing.

  In the above embodiment, the eccentric shaft 72 is fixed to the second housing 34 and the slide bearing 71 is fixed to the drive pulley 41. However, the eccentric shaft 72 is fixed to the drive pulley 41 and the slide bearing 71 is fixed to the second housing 34. It can also be fixed.

In the above embodiment, the slide bearing 71 can be omitted. In this case, the drive pulley 41 and the shaft portion 73 of the eccentric shaft 72 slide.
In the above embodiment, the drive pulley 41 around which the belt 47 is wound around the right end portion of the second attachment portion 43 is used, but the drive pulley 80 shown in FIG. You can also.

  The drive pulley 80 is provided with a first attachment portion 81 corresponding to the first attachment portion 42 of the drive pulley 41 and a second attachment portion 82 corresponding to the second attachment portion 43 of the drive pulley 41. The second attachment portion 82 is provided with a winding portion 83 around which the belt 47 is wound and a support portion 84 supported by the second bearing mechanism 70. That is, the belt 47 is wound around a portion (a winding portion 83) closer to the first attachment portion 81 than the support portion 84 in the axial direction of the second attachment portion 82.

  In the drive pulley 80, an insertion hole 85 for inserting the shaft portion 73 of the eccentric shaft 72 is formed in the support portion 84. A slide bearing 71 that supports the shaft portion 73 of the eccentric shaft 72 is attached to the insertion hole 85.

  In the above embodiment, the winding transmission device 40 including the driving pulley 41, the driven pulley 46, and the belt 47 is used. However, the winding transmission device 40 is replaced with a driving sprocket, a driven sprocket, and a chain. It is also possible to use a winding transmission device.

  In the above embodiment, the present invention is applied to the so-called rack assist type electric power steering apparatus 1 in which the electric motor 21 is attached to the steered shaft 13, but the electric power steering apparatus to which the present invention can be applied is the same. It is not restricted to what was illustrated to embodiment. For example, the present invention can be applied to a so-called column-type electric power steering apparatus in which an electric motor is attached to a steering shaft, or a so-called pinion-type electric power steering apparatus in which an electric motor is attached to a pinion of a rack and pinion mechanism.

  DESCRIPTION OF SYMBOLS 1 ... Electric power steering apparatus, 10 ... Steering angle transmission mechanism, 11 ... Steering shaft, 12 ... Rack and pinion mechanism, 13 ... Steering shaft, 13A ... Left end part, 13B ... Right end part, 20 ... Assist device, 21 ... Electricity Motor, 21A ... output shaft, 21B ... main body, 22 ... ball screw device, 23 ... bolt, 30 ... housing, 31 ... first housing, 32 ... first main body, 33 ... first enlarged diameter part, 33A ... first 1 through hole, 33B ... annular groove, 33C ... flange, 33D ... bolt insertion hole, 34 ... second housing, 35 ... second body part, 36 ... second enlarged diameter part, 36A ... second through hole, 36B ... Right side, 37 ... reduced diameter part, 40 ... winding transmission device, 41 ... drive pulley (drive rotator), 42 ... first attachment part, 43 ... second attachment part, 44 ... first insertion hole, 45 ... second Insertion hole, 46 Drive pulley (driven rotor), 47 ... belt (rotation transmission), 50 ... first bearing mechanism, 51 ... spacer, 52 ... support part, 53 ... regulating part, 54 ... flange, 55 ... bearing insertion hole, 56 ... C ring, 60 ... ball bearing (bearing), 61 ... inner ring, 62 ... outer ring, 63 ... rolling element, 70 ... second bearing mechanism, 71 ... slide bearing, 72 ... eccentric shaft (shaft), 73 ... shaft part, 74 ... head, 75 ... through hole, 76 ... plane part, 77 ... reduced diameter part, 78 ... bolt, 80 ... drive pulley (drive rotator), 81 ... first attachment part, 82 ... second attachment part, 83 ... winding part, 84 ... support part, 85 ... insertion hole.

Claims (6)

An electric motor that assists the linear motion of the steered shaft, a ball screw device that converts the rotation of the electric motor into a linear motion, a winding transmission device that transmits the rotation of the electric motor to the ball screw device, and the winding A first bearing mechanism and a second bearing mechanism for supporting a driving rotating body of a hanging transmission device; the driving rotating body attached to the electric motor; a driven rotating body attached to the ball screw device; In the electric power steering apparatus in which the drive transmission body and the rotation transmission body wound around the driven rotation body are provided in the winding transmission apparatus,
A portion of the drive rotator that is attached to the output shaft of the electric motor and includes one end in the axial direction of the drive rotator is a first attachment portion. 1 is a part different from the attachment part, and the part including the other end in the axial direction of the drive rotator as the second transmission part is wound around the rotation transmission body,
The first mounting portion is supported by the first bearing mechanism;
The second mounting portion is supported by the second bearing mechanism;
The electric power steering apparatus is characterized in that the second bearing mechanism supports the second mounting portion inside the second mounting portion. The electric power steering apparatus according to claim 1, wherein
A housing for accommodating the winding transmission is provided;
The first bearing mechanism is provided with a bearing that supports the first mounting portion of the drive rotating body, and a spacer that restricts movement of the bearing relative to the housing between the housing and the bearing. ,
The second bearing mechanism is provided with a shaft that is inserted into the second mounting portion and supports the second mounting portion;
The shaft is provided with a shaft portion inserted into the drive rotator and a head portion fixed to the housing;
The hole formed in the spacer and into which the bearing is fitted is a bearing fitting hole, and the center line of the bearing fitting hole is eccentric with respect to the center line of the spacer,
The center line of the shaft is eccentric with respect to the center line of the head;
The center line of the output shaft of the electric motor, the center line of the drive rotating body, and the center line of the shaft match,
In addition, an electric power steering apparatus, wherein a center line of the bearing fitting hole and a center line of the head coincide with each other. In the electric power steering apparatus according to claim 1 or 2,
A housing for accommodating the winding transmission is provided;
The second bearing mechanism is provided with a shaft that is inserted into the second mounting portion and supports the second mounting portion;
The shaft is fixed to the housing;
The electric power steering apparatus is characterized in that the second bearing mechanism is provided with a slide bearing for supporting the shaft between the shaft and the drive rotating body. In the electric power steering device according to any one of claims 1 to 3,
The electric power steering apparatus, wherein the rotary transmission body is wound around the other end portion of the second mounting portion of the drive rotary body. In the electric power steering apparatus according to claim 4,
The shaft is provided with a shaft portion inserted into the second mounting portion of the drive rotor and a head fixed to the housing.
The head is provided outside the housing;
In addition, a portion corresponding to the head in the housing is used as a head fixing portion, and the head fixing portion and the second mounting portion of the drive rotating body are adjacent to each other with a gap. Power steering device. In the manufacturing method of the electric power steering device according to claim 5,
Assembling an assembly that satisfies the following conditions (a) to (e), wherein the housing and the winding transmission device and the first bearing mechanism and the second bearing mechanism are combined with each other:
(A) “The bearing is attached to the first attachment portion of the drive rotating body”
(B) “The spacer is attached between the housing and the bearing”
(C) “The spacer can be rotated with respect to the housing”
(D) “The shaft portion of the shaft is inserted into the second mounting portion of the drive rotor”
(E) “The shaft can rotate relative to the housing”
Adjusting the tension of the rotary transmission of the assembly after step A;
Step C after fixing the shaft head to the housing after Step B;
A step D of fixing the electric motor to the assembly after the step C;
In the step B, the driving rotating body, the bearing, the spacer, and the shaft are integrally rotated with the shaft head and the center line of the bearing fitting hole of the spacer as the rotation center. An electric power steering device characterized in that a distance between a rotation center of a rotating body and a rotation center of the driven rotating body is changed, and the tension of the rotating transmission body is adjusted to a magnitude within a predetermined range by changing the distance. Manufacturing method.

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