JP6135179B2 - Steering device - Google Patents

Description

The present invention relates to a steering equipment having a structure in which a driven pulley fixed to a drive pulley and a ball screw mechanism for rotating the output shaft integral with the electric motor are connected by a belt.

  A conventional steering device includes an electric motor, a drive pulley connected to an output shaft of the electric motor, a ball screw mechanism that reciprocates a rack shaft, a driven pulley fixed to the ball screw mechanism, a drive pulley, and a driven pulley And a belt connecting the pulleys. In the conventional steering device, the rotation of the output shaft of the electric motor is transmitted to the ball nut of the ball screw mechanism via the belt. The conventional steering device reciprocates the rack shaft as the ball nut rotates.

  In the conventional steering apparatus, the belt tension is adjusted in order to suppress variations in belt tension. The conventional steering apparatus changes the position of the drive pulley with respect to the driven pulley by changing the position of the electric motor with respect to the ball screw mechanism. Thereby, since the center-to-center distance between the driving pulley and the driven pulley is changed, the belt tension is changed. Note that Patent Document 1 shows an example of a conventional steering device.

JP 2008-307980 A

  In the conventional steering device, the electric motor and the driving pulley are moved for adjusting the tension of the belt. For this reason, it is necessary to move the total weight of the electric motor and the drive pulley, and it is difficult to adjust the belt tension.

The present invention has been made in light of the above background, and an object thereof is to provide a turning equipment capable of adjusting the tension of the belt easily.

The means includes: “an electric motor, a driving pulley that rotates integrally with an output shaft of the electric motor, a driven pulley that rotates as the driving pulley rotates via a belt, and a rack shaft that reciprocates in an axial direction. And a ball screw mechanism that reciprocates the rack shaft by rotating with the rotation of the driven pulley, a housing to which the electric motor is attached, and a fixing component that fixes the driving pulley to the housing. The pulley includes a pulley body that is wound around the belt and rotates integrally with the output shaft, a pulley housing that is attached to the housing and accommodates a part of the pulley body, and the pulley body that rotates relative to the pulley housing. A bearing that supports the pulley body in a state in which the housing is possible, and the housing Has a pulley insertion hole over Li body is inserted, said drive pulley, the closer or away with respect to the driven pulley is inserted in the pulley insertion hole in a state as possible, the pulley insertion hole, the drive pulley is the The pulley housing is formed as a long hole that can approach or separate from the driven pulley, and the pulley housing has a flange portion that is sandwiched between the housing and the fixed component, and the housing has a pulley mounting portion that accommodates the flange portion. The outer shape of the flange portion is formed in an elliptical shape, and the long axis of the flange portion is the center of the drive pulley and the inner peripheral surface of the pulley mounting portion when the drive pulley is closest to the driven pulley. A steering device that is greater than twice the distance between .

In this steering apparatus, the drive pulley is fixed to the housing by a fixing component. For this reason, the drive pulley can be fixed to the housing by the fixing component in a state where the position of the drive pulley relative to the driven pulley is changed, that is, in a state where the belt tension is adjusted. This avoids moving the electric motor in adjusting the belt tension. Therefore, it is easier to adjust the belt tension as compared with the configuration in which both the electric motor and the driving pulley are assumed to move in adjusting the belt tension.
In this steering device, the long axis of the flange is larger than twice the distance between the center of the drive pulley and the inner peripheral surface of the pulley mounting portion when the drive pulley is closest to the driven pulley. And the area of the collar part pinched | interposed by fixing components becomes large. Therefore, the tightening torque of the fixed part can be reduced. For this reason, since the force which acts on a fixed component from the collar part resulting from a fastening torque becomes small, the required thickness of a fixed component can be made small. Therefore, the fixed part is reduced in size.

One mode of the above means includes a “steering device in which the long axis of the flange portion is orthogonal to the longitudinal direction of the pulley insertion hole”.
In this steered device, the area of the eaves portion sandwiched between the housing and the fixed part becomes larger. Therefore, the fastening torque of the fixed part can be further reduced. Therefore, the fixed component can be further downsized.

This steering equipment may adjust the tension of the belt easily.

The block diagram which shows the structure of a vehicle provided with the steering apparatus of embodiment. The disassembled perspective view of the rear-wheel steering apparatus of embodiment. It is sectional drawing of the rear-wheel steering apparatus of embodiment, and sectional drawing of the Z2-Z2 line | wire of FIG. Sectional drawing of the drive pulley of embodiment and its periphery. The top view of the pulley attachment part of the 1st housing of embodiment. The top view of the state in which the drive pulley was attached to the pulley attachment part of embodiment. The flowchart of the belt tension adjustment method of the steering apparatus of embodiment. The top view of the state in which the drive pulley was attached to the pulley attachment part of embodiment.

With reference to FIG. 1, the structure of the vehicle 1 is demonstrated.
The vehicle 1 includes a steering component 2, a front wheel 3F, a rear wheel 3R, a front wheel steering device 10, a rear wheel steering device 20, and a control device 110. The vehicle 1 controls the operations of the front wheel steering device 10 and the rear wheel steering device 20 based on the operation of the steering component 2 by the control device 110. The vehicle 1 changes the turning angles of the front wheels 3F and the rear wheels 3R by the front wheel steering device 10 and the rear wheel steering device 20 based on the operation of the steering component 2. The vehicle 1 changes the turning angle of the rear wheel 3 </ b> R by the rear wheel turning device 20 for the purpose of reducing the turning radius of the vehicle 1 during turning of the vehicle 1. The rear wheel steering device 20 corresponds to a “steering device”.

  The front wheel steering device 10 includes a steering shaft 11, a rack and pinion mechanism 12, a front wheel rack shaft 13, two front wheel tie rods 14, and an assist device 15. The front wheel steering device 10 converts the rotation of the steering shaft 11 into the reciprocating motion of the front wheel rack shaft 13 by the rack and pinion mechanism 12. The front wheel steering device 10 steers the front wheel 3 </ b> F via the front wheel tie rod 14 by the reciprocating motion of the front wheel rack shaft 13.

The steering shaft 11 is connected to the steering component 2 at one end. The steering shaft 11 is connected to the front wheel rack shaft 13 at the other end.
The rack and pinion mechanism 12 has pinion teeth 11 </ b> A formed on the other end of the steering shaft 11 and rack teeth 13 </ b> A formed on the front wheel rack shaft 13. The rack and pinion mechanism 12 converts the rotation of the steering shaft 11 into the reciprocating motion of the front wheel rack shaft 13.

  The front wheel rack shaft 13 is connected to a front wheel tie rod 14 at both ends. The front wheel rack shaft 13 reciprocates to change the turning angle of the front wheel 3F via the front wheel tie rod 14.

  The assist device 15 includes an assist motor 16 and a speed reduction mechanism 17 as a worm gear. The assist device 15 has a configuration in which the speed reduction mechanism 17 is fixed to the steering shaft 11 and connected to the output shaft of the assist motor 16. The assist device 15 gives the steering shaft 11 a force for rotating the steering shaft 11 by transmitting the rotation of the assist motor 16 to the steering shaft 11 while being decelerated by the speed reduction mechanism 17.

  The rear wheel steering device 20 includes a rear wheel rack shaft 21, two rear wheel tie rods 22, a rack housing 23, and a drive device 30. The rear wheel steering device 20 has a configuration in which rear wheel tie rods 22 are connected to both ends of a rear wheel rack shaft 21. The rear wheel steering device 20 has a rack parallel type configuration in which the rear wheel rack shaft 21 and the electric motor 31 of the drive device 30 are parallel to each other. The rear wheel steering device 20 reciprocates the rear wheel rack shaft 21 by the drive device 30. The rear wheel steering device 20 steers the rear wheel 3 </ b> R via the rear wheel tie rod 22 by the reciprocating motion of the rear wheel rack shaft 21. The rear wheel rack shaft 21 corresponds to a “rack shaft”. The rack housing 23 corresponds to a “housing”.

  The detailed configuration of the rear wheel steering device 20 will be described with reference to FIGS. 2 and 3. The “axial direction ZA” indicates a direction along the axial direction of the rear wheel rack shaft 21. The “radial direction ZB” indicates a normal direction of the axial direction ZA.

  As shown in FIG. 2, the rack housing 23 accommodates a part of the rear wheel rack shaft 21 and the drive device 30. The rack housing 23 includes a first housing 90 and a second housing 100. The rack housing 23 has a configuration in which the first housing 90 and the second housing 100 are fastened to each other by a plurality of bolts (not shown).

  The drive device 30 includes an electric motor 31, a belt 33 (see FIG. 3), a drive pulley 40, a driven pulley 34 (see FIG. 3), a lock nut 70 as a fixed part, and a ball screw mechanism 80 (see FIG. 3). . The driving device 30 transmits the rotation of the output shaft 31 </ b> A of the electric motor 31 to the ball screw mechanism 80 while being decelerated by the driving pulley 40, the belt 33, and the driven pulley 34. The drive device 30 converts the rotation of the output shaft 31 </ b> A of the electric motor 31 into the reciprocating motion of the rear wheel rack shaft 21 by the ball screw mechanism 80.

A detailed configuration of the rack housing 23 will be described with reference to FIG.
The first housing 90 has a housing body 91 and a flange 93. The first housing 90 has a configuration in which a housing body 91 and a flange 93 are integrally formed of the same material.

  The housing body 91 has a cylindrical shape extending in the axial direction ZA. The housing body 91 has a bearing support portion 92. The housing main body 91 has a configuration in which the diameter of the bearing support portion 92 is larger than that of other portions. The housing main body 91 accommodates the ball bearing 36 in the bearing support portion 92.

  The flange 93 has four bolt insertion holes 94 and a pulley mounting portion 95. The flange 93 projects in the radial direction ZB from the end of the bearing support portion 92 in the axial direction ZA. The flange 93 has a substantially rectangular shape in plan view from the axial direction ZA.

  Bolt insertion hole 94 is formed as a long hole whose longitudinal direction is a direction along a straight line connecting the central axis of rear wheel rack shaft 21 and the central axis of output shaft 31A of electric motor 31 (hereinafter referred to as “pulley movement direction PM”). Has been.

  The second housing 100 has a housing body 101 and a flange 103. The second housing 100 has a configuration in which the housing main body 101 and the flange 103 are integrally formed of the same material.

  The housing body 101 has a cylindrical shape extending in the axial direction ZA. The housing body 101 has a bearing support portion 102. The housing body 101 has a configuration in which the diameter of the bearing support portion 102 is larger than that of other portions. The housing body 101 accommodates two ball bearings 35 in the bearing support portion 102.

The flange 103 has a belt accommodating portion 104, an extension portion 105, and four bolt insertion holes 106.
The belt accommodating portion 104 accommodates the belt 33. The extension portion 105 extends in the radial direction ZB from the end of the belt housing portion 104 opposite to the bearing support portion 102 in the radial direction ZB. The bolt insertion hole 106 is formed at a position corresponding to the bolt insertion hole 94 of the first housing 90 in the belt accommodating portion 104 and the extension portion 105. The bolt insertion hole 106 is formed as a long hole whose pulley moving direction PM is the longitudinal direction.

With reference to FIG. 3, the detailed structure of the drive device 30 is demonstrated.
The electric motor 31 is fixed to the flange 93 of the first housing 90 by a fixing bolt 32. The electric motor 31 is coupled to the drive pulley 40 on the output shaft 31A.

  The drive pulley 40 is located in the pulley mounting portion 95 and the belt accommodating portion 104. The drive pulley 40 is fixed to the pulley mounting portion 95 by a lock nut 70. The drive pulley 40 rotates integrally with the output shaft 31A.

  The ball screw mechanism 80 includes a male screw portion 21A of the rear wheel rack shaft 21, a ball nut 81, and a plurality of balls 82. The ball screw mechanism 80 has a configuration in which a plurality of balls 82 are accommodated in a rolling path 83 formed by the male screw portion 21A of the rear wheel rack shaft 21 and the female screw portion 81A of the ball nut 81. The ball screw mechanism 80 converts the rotation of the ball nut 81 into the reciprocating motion of the rear rack shaft 21 by the infinite circulation of the plurality of balls 82 as the ball nut 81 rotates.

  The ball nut 81 has a cylindrical shape. The ball nut 81 is supported by the second housing 100 by two ball bearings 35 so as to be rotatable with respect to the second housing 100. The ball nut 81 is supported by the first housing 90 so as to be rotatable with respect to the first housing 90 by the ball bearing 36.

  The driven pulley 34 is fixed to the outer peripheral surface of the ball nut 81. The driven pulley 34 is located between the ball bearing 35 and the ball bearing 36 in the axial direction ZA. The driven pulley 34 is restricted from moving in the axial direction ZA by the ball nut 81 and the ball bearing 35.

  The belt 33 is wound around the drive pulley 40 and the driven pulley 34. The belt 33 rotates the driven pulley 34 by transmitting the rotation of the driving pulley 40 to the driven pulley 34.

With reference to FIG. 4, the detailed structure of the pulley attachment part 95 is demonstrated.
The pulley mounting portion 95 passes through the flange 93 in the axial direction ZA. The pulley attachment portion 95 has a screw portion 96, a pulley support portion 97, and a pulley insertion hole 98.

The screw portion 96 is formed on the inner peripheral surface 95 </ b> A of the pulley mounting portion 95 at a portion on the electric motor 31 side.
The pulley support portion 97 protrudes from the inner peripheral surface 95 </ b> A of the portion on the belt 33 side toward the drive pulley 40 in the pulley attachment portion 95. The pulley support portion 97 has an annular shape in a plan view of the pulley attachment portion 95 in the axial direction ZA.

  The pulley insertion hole 98 passes through the pulley support portion 97 in the axial direction ZA. The pulley insertion hole 98 communicates the internal space of the belt housing portion 104 with the internal space of the pulley mounting portion. The pulley insertion hole 98 is formed with inclined portions 98C at both end portions in the axial direction ZA. The inclined portion 98C is formed by chamfering.

A detailed configuration of the drive pulley 40 will be described with reference to FIG.
The drive pulley 40 includes a pulley body 50, a pulley housing 60, two ball bearings 41 as bearings, and a retaining ring 42.

  The pulley body 50 is inserted into the pulley insertion hole 98. The pulley main body 50 includes a belt attachment portion 51, a shaft portion 52, a step portion 53, and a fitting hole 54. The pulley main body 50 has a configuration in which a belt attaching portion 51, a shaft portion 52, and a stepped portion 53 are integrally formed of the same material.

  The belt attachment portion 51 is formed in a portion of the pulley main body 50 on the belt 33 side. The belt attaching portion 51 is accommodated in the belt accommodating portion 104 of the second housing 100. The belt attachment portion 51 has a gear formed at the outer peripheral portion. The belt attachment portion 51 is meshed with the belt 33 in the gear.

The shaft portion 52 is formed in a portion of the pulley body 50 on the electric motor 31 side. The shaft portion 52 is supported by two ball bearings 41 on the outer peripheral surface.
The step portion 53 is formed between the belt attaching portion 51 and the shaft portion 52. The step portion 53 supports the ball bearing 41 in the axial direction ZA.

  The fitting hole 54 is recessed from the end surface of the shaft portion 52 on the electric motor 31 side toward the axial direction ZA. As for the fitting hole 54, the spline is formed in the internal peripheral surface. In the fitting hole 54, the output shaft 31A is fixed.

  The pulley housing 60 has a bearing support portion 61 and a flange portion 62. The pulley housing 60 has a configuration in which a bearing support portion 61 and a flange portion 62 are integrally formed of the same material. The pulley housing 60 is located in the pulley mounting portion 95. An end of the pulley housing 60 on the side of the electric motor 31 protrudes further toward the electric motor 31 than the pulley mounting portion 95.

  The bearing support portion 61 has a cylindrical shape. The bearing support portion 61 has a reduced diameter portion 61A at the end portion on the electric motor 31 side. The bearing support portion 61 supports the ball bearing 41 in the axial direction ZA at the reduced diameter portion 61A.

  The flange portion 62 protrudes in the radial direction ZB from the outer peripheral surface of the portion on the belt 33 side in the bearing support portion 61. The flange portion 62 is sandwiched between the pulley support portion 97 and the lock nut 70 in the axial direction ZA.

  The ball bearing 41 is fixed to the inner peripheral surface of the bearing support portion 61 at a portion closer to the belt 33 than the reduced diameter portion 61A. The two ball bearings 41 are sandwiched between the stepped portion 53 of the pulley body 50 and the retaining ring 42 in the axial direction ZA. The two ball bearings 41 support the pulley body 50 in a state in which the pulley body 50 can rotate with respect to the pulley housing 60.

A detailed configuration of the lock nut 70 and a fixing structure of the drive pulley 40 will be described with reference to FIG.
The lock nut 70 has an annular shape in a plan view of the lock nut 70. The lock nut 70 has a fitting portion 71 and a screw portion 72.

  The fitting portion 71 is formed at the end of the lock nut 70 on the electric motor 31 side. The fitting part 71 has an uneven shape in the axial direction ZA. The fitting portion 71 is formed over the entire circumference of the lock nut 70. The fitting portion 71 is fitted with a tool (not shown) for fixing the lock nut 70 to the pulley mounting portion 95.

  The threaded portion 72 is formed on the outer peripheral surface of the portion of the lock nut 70 on the belt 33 side. The screw portion 72 is screwed with the screw portion 96 of the pulley attachment portion 95 in a state where the lock nut 70 is fixed to the pulley attachment portion 95.

  The drive pulley 40 is supported by the pulley support portion 97 at the flange portion 62. The lock nut 70 presses the flange portion 62 against the belt 33 side by being screwed into the screw portion 96 of the pulley attachment portion 95. The flange portion 62 is sandwiched in the axial direction ZA by the pulley support portion 97 and the lock nut 70.

The shape of the pulley insertion hole 98 will be described with reference to FIG.
The pulley insertion hole 98 is formed as a long hole in which the pulley moving direction PM is a longitudinal direction in the plan view of the pulley mounting portion 95. The pulley insertion hole 98 has a pair of curved portions 98A and a flat portion 98B.

  The curved portion 98A is formed at the end of the pulley insertion hole 98 in the pulley movement direction PM. The pair of curved portions 98A are separated from each other in the pulley movement direction PM. The curved portion 98A has a semicircular shape.

  The flat portion 98B is located between the pair of curved portions 98A in the pulley movement direction PM. The flat portion 98B connects the pair of curved portions 98A to each other. The flat portion 98B extends in parallel to the pulley movement direction PM.

  With reference to FIGS. 5 and 6, the relationship between the pulley mounting portion 95 and the drive pulley 40 will be described. Note that the “approach direction PM1” indicates a direction of approaching the driven pulley 34 in the pulley movement direction PM. The “separation direction PM2” indicates a direction away from the driven pulley 34 in the pulley movement direction PM. FIG. 6 shows a state in which the drive pulley 40 has moved most in the approach direction PM1 of the pulley movement direction PM. In FIGS. 5 and 6, the inclined portion 98C is omitted.

  An end portion of the bearing support portion 61 of the pulley housing 60 on the belt 33 (see FIG. 4) side is inserted into the pulley insertion hole 98 while being fixed to the pulley mounting portion 95. The bearing support portion 61 has a circular outer shape in a plan view of the drive pulley 40. The outer radius RP of the bearing support 61 is equal to the inner diameter RH (see FIG. 5) of the curved portion 98A. The outer diameter dimension DP of the bearing support portion 61 is smaller than the dimension DH1 (see FIG. 5) of the pulley insertion hole 98 in the pulley movement direction PM. The outer diameter dimension DP of the bearing support portion 61 is equal to the dimension DH2 (see FIG. 5) of the pulley insertion hole 98 orthogonal to the pulley movement direction PM in the plan view of the pulley mounting portion 95.

  The flange portion 62 of the pulley housing 60 has an elliptical shape in a plan view of the drive pulley 40. The flange portion 62 has a major axis MA (longitudinal direction) in a direction orthogonal to the pulley movement direction PM in a plan view of the drive pulley 40.

  Specifically, the flange portion 62 is a distance between the arc having a radius RB1 between the center C1 and the curved portion 98A on the separation direction PM2 side and the curved portion 98A on the approach direction PM1 side with the radius RB1. And a circular arc having a radius RB2 at the center CP. Note that the center C1 coincides with the center CH (see FIG. 5) of the pulley mounting portion 95 when the drive pulley 40 moves most in the separation direction PM2 of the pulley movement direction PM. The center C2 coincides with the center CH of the pulley mounting portion 95 when the drive pulley 40 moves most in the approach direction PM1 of the pulley movement direction PM. The long axis MA of the flange portion 62 is a distance DH3 between the center CP of the drive pulley 40 and the inner peripheral surface 95A of the pulley attachment portion 95 in a state where the drive pulley 40 has moved most in the approach direction PM1 of the pulley movement direction PM. Greater than twice.

  The flange portion 62 is an inner peripheral surface 95A of the pulley mounting portion 95 in a state where the drive pulley 40 is most moved in the approach direction PM1 of the pulley movement direction PM, that is, in a state where the drive pulley 40 is in contact with the curved portion 98A on the approach direction PM1 side. Contact with. Further, the flange portion 62 has an inner peripheral surface 95A of the pulley mounting portion 95 in a state where the drive pulley 40 is moved most in the separation direction PM2 of the pulley movement direction PM, that is, in a state where the drive pulley 40 is in contact with the curved portion 98A in the separation direction PM2. Contact with.

  With reference to FIG. 7, the belt tension adjustment method of the rear-wheel steering apparatus 20 is demonstrated. In the following description with reference to FIG. 7, each component of the rear wheel steering device 20 denoted by a reference numeral indicates each component of the rear wheel steering device 20 described in FIG. 3. In FIG. 7, the inclined portion 98C is omitted.

The belt tension adjusting method includes a ball screw mechanism assembling step, a pulley inserting step, a tension adjusting step, a pulley fixing step, and a motor fixing step.
In the ball screw mechanism assembling step (step S11), the ball nut 81 is assembled to the rear wheel rack shaft 21 via a plurality of balls 82. Further, the driven pulley 34 is fixed to the ball nut 81. In the ball screw mechanism assembly process, the ball bearings 35 and 36 are attached to the rack housing 23 and the ball nut 81. Further, the belt 33 is wound around the driven pulley 34.

In the pulley insertion step (step S12), the drive pulley 40 is inserted into the pulley mounting portion 95. The drive pulley 40 is in a state in which the flange portion 62 is supported by the pulley support portion 97.
In the tension adjustment step (step S13), the belt 33 is wound around the belt mounting portion 51 of the drive pulley 40. A sonic belt tension meter (not shown) is attached to a part of the flange 93 of the first housing 90. In the tension adjustment step, the tension of the belt 33 is adjusted based on the measurement result of the sonic belt tension meter.

  The sonic belt tension meter calculates the tension of the belt 33 by measuring the frequency of the belt 33 based on the proportional relationship between the tension of the belt 33 and the vibration frequency when the belt 33 is vibrated.

In the tension adjusting step, the tension of the belt 33 is changed by the drive pulley 40 moving in the pulley moving direction PM.
Specifically, the distance between the centers of the drive pulley 40 and the driven pulley 34 is reduced as the drive pulley 40 moves in the approach direction PM1. Thereby, the tension of the belt 33 is reduced. Further, when the drive pulley 40 moves in the separation direction PM2, the center distance between the drive pulley 40 and the driven pulley 34 increases. As a result, the tension of the belt 33 increases. In the tension adjustment step, the position of the drive pulley 40 in the pulley movement direction PM is changed so that the belt 33 is within the designed tension range. Note that the center-to-center distance between the drive pulley 40 and the driven pulley 34 indicates a straight line connecting the center CP of the drive pulley 40 and the center of the driven pulley 34 in plan view from the axial direction ZA.

  In the pulley fixing step (step S14), the lock nut 70 is attached to the pulley attachment portion 95. The lock nut 70 fixes the drive pulley 40 to the rack housing 23 by sandwiching the flange portion 62 between the lock nut 70 and the pulley support portion 97. As a result, the drive pulley 40 is fixed to the rack housing 23 at a position in the pulley movement direction PM of the drive pulley 40 with respect to the pulley insertion hole 98 determined in the tension adjustment step.

  In the motor fixing step (step S15), the output shaft 31A of the electric motor 31 is fitted into the fitting hole 54 of the drive pulley 40. The electric motor 31 is fastened to the rack housing 23 by the four fixing bolts 32 through the bolt insertion holes 94 and 106.

The effect | action of the rear-wheel steering apparatus 20 of this embodiment is demonstrated.
The rear wheel steering device 20 has a first function and a second function. The first function is a function that facilitates adjustment of the tension of the belt 33. The second function is a function capable of reducing the size of the lock nut 70.

The detailed contents of the first function will be described. The “comparison steering device” indicates a configuration in which the tension of the belt 33 is adjusted in a state where the electric motor 31 and the drive pulley 40 are connected.
In the comparative steering device, it is necessary to move both the electric motor 31 and the drive pulley 40 in order to adjust the tension of the belt 33. For this reason, it is necessary to adjust the tension of the belt 33 by moving the total weight of the electric motor 31 and the drive pulley 40, and the tension of the belt 33 is difficult to adjust.

  On the other hand, in the rear wheel steering device 20 of the present embodiment, the tension of the belt 33 is adjusted by the movement of the drive pulley 40 in the tension adjustment step. After adjusting the tension of the belt 33, the electric motor 31 is fixed to the rack housing 23 in the motor fixing step. For this reason, in order to adjust the tension of the belt 33, only the drive pulley 40 needs to be moved. Therefore, the tension of the belt 33 can be easily adjusted as compared with the comparative turning device.

  The detailed contents of the second function will be described with reference to FIG. Note that the “comparison pulley” has a circular shape (two-dot chain line in FIG. 8) in which the flange portion is concentric with the center CP of the drive pulley 40 in a plan view of the comparison pulley. FIG. 8 shows a state in which the drive pulley 40 has moved most in the approach direction PM1 of the pulley movement direction PM.

  The flange portion 62 of the drive pulley 40 of this embodiment has a larger area in contact with the pulley support portion 97 than the flange portion of the comparative pulley by the area indicated by the oblique lines in FIG. Further, the flange portion 62 of the drive pulley 40 has a larger area in contact with the lock nut 70 than the flange portion of the comparison pulley by the area indicated by the hatched lines in FIG. For this reason, the flange 62 of the drive pulley 40 has a larger area sandwiched between the pulley support 97 and the lock nut 70 than the flange of the comparison pulley. As a result, the frictional force between the flange 62 of the drive pulley 40 and the pulley support 97 and the friction force between the lock nut 70 and the flange of the comparison pulley are larger. For this reason, even if the tightening torque with respect to the flange portion 62 of the lock nut 70 set in advance is reduced, the movement of the flange portion 62 from the lock nut 70 is restricted. Further, the lock nut 70 is restrained from being loosened by the force that the flange 62 acts on the lock nut 70 due to the tightening torque. Therefore, it is possible to reduce the tightening torque with respect to the flange portion 62 of the lock nut 70. For this reason, since the force acting on the lock nut 70 from the flange 62 due to the tightening torque is reduced, the thickness of the threaded portion 72 of the lock nut 70 required to restrict the lock nut 70 from being loosened is reduced. can do. Therefore, the lock nut 70 can be reduced in size.

The rear wheel steering device 20 of the present embodiment has the following effects.
(1) The rear wheel steering device 20 has a pulley insertion hole 98 through which the drive pulley 40 can move in the pulley movement direction PM. According to this configuration, the center-to-center distance between the drive pulley 40 and the driven pulley 34 can be changed in the pulley movement direction PM. Therefore, the tension of the belt 33 can be adjusted. In addition, since the drive pulley 40 is fixed to the first housing 90 by the lock nut 70, the tension of the belt 33 is adjusted by changing the position of the drive pulley 40. Therefore, the tension of the belt 33 can be easily adjusted as compared with the configuration in which the tension of the belt 33 is assumed to be adjusted by changing the positions of both the electric motor 31 and the drive pulley 40.

  (2) The long axis MA of the flange portion 62 of the pulley housing 60 is the distance between the center CP of the drive pulley 40 and the inner peripheral surface 95A of the pulley mounting portion 95 when the drive pulley 40 is closest to the driven pulley 34. Greater than twice DH3. According to this configuration, as shown in FIG. 8, the area of the flange portion 62 sandwiched between the pulley support portion 97 and the lock nut 70 is increased. Therefore, the tightening torque of the lock nut 70 can be reduced. For this reason, since the force which acts on the lock nut 70 from the collar part 62 resulting from a fastening torque becomes small, the thickness of the thread part 72 of the lock nut 70 can be made small. Therefore, the lock nut 70 is reduced in size.

  (3) The long axis MA of the flange portion 62 is orthogonal to the pulley movement direction PM. According to this configuration, the long axis MA of the flange 62 is orthogonal to the longitudinal direction of the pulley insertion hole 98. For this reason, the area of the collar part 62 pinched by the pulley support part 97 and the lock nut 70 becomes larger. Therefore, the lock nut 70 can be further downsized.

  (4) The dimension DH2 of the pulley insertion hole 98 orthogonal to the pulley moving direction PM is equal to the outer diameter dimension DP of the bearing support portion 61 of the pulley housing 60. According to this configuration, the drive pulley 40 is restricted from moving in a direction orthogonal to the pulley movement direction PM. For this reason, it is suppressed that the bolt fixing hole (not shown) of the electric motor 31 shifts in the direction orthogonal to the bolt insertion holes 94 and 106 of the rack housing 23 and the pulley moving direction PM. Therefore, the electric motor 31 is easily fixed to the rack housing 23 by the fixing bolt 32.

  The turning apparatus and the belt tension adjusting method of the turning apparatus include an embodiment different from the above embodiment. Hereinafter, the modification of the said embodiment as other embodiment of the belt tension adjustment method of this steering apparatus and this steering apparatus is shown. The following modifications can be combined with each other.

  -The pulley insertion hole 98 of embodiment is formed as a long hole which has a pair of curved part 98A and the flat part 98B. However, the shape of the pulley insertion hole 98 is not limited to the content exemplified in the embodiment. For example, the modified pulley insertion hole 98 is formed in a circular shape in plan view of the pulley insertion hole 98. The inner diameter of the pulley insertion hole 98 of the modification is larger than the outer diameter dimension DP of the bearing support portion 61 of the pulley housing 60. Moreover, the pulley insertion hole 98 of another modification has an elliptical shape in a plan view of the pulley insertion hole 98. The major axis of the pulley insertion hole 98 of another modification is parallel to the pulley movement direction PM. The major axis of the pulley insertion hole 98 of another modification is larger than the outer diameter dimension DP of the bearing support portion 61.

  -The pulley insertion hole 98 of embodiment has a pair of flat part 98B. However, the shape of the pulley insertion hole 98 is not limited to the content exemplified in the embodiment. For example, the pulley insertion hole 98 of the modification has a shape in which any one of the pair of flat portions 98B is omitted. In the pulley insertion hole 98 of the modified example, the omitted flat portion 98B is formed in a curved shape that connects the pair of curved portions 98A to each other in the pulley movement direction PM.

  -The collar part 62 of embodiment is formed by making the direction orthogonal to the pulley moving direction PM into the major axis MA. However, the shape of the collar part 62 is not restricted to the content illustrated by embodiment. For example, the flange portion 62 of the modification is formed with a major axis MA in a direction other than the direction along the pulley movement direction PM and the direction orthogonal to the pulley movement direction PM.

  -The collar part 62 of embodiment is formed in the ellipse shape in planar view of the collar part 62. As shown in FIG. However, the shape of the collar part 62 is not restricted to the content illustrated by embodiment. For example, the flange portion 62 of the modified example is formed in a circular shape in the plan view of the flange portion 62.

  -The collar part 62 of embodiment contacts the inner peripheral surface 95A of the pulley attachment part 95 in the state which the drive pulley 40 moved most to the approach direction PM1 of the pulley moving direction PM. Further, the flange portion 62 comes into contact with the inner peripheral surface 95A of the pulley mounting portion 95 in a state where the drive pulley 40 is most moved in the separation direction PM2 of the pulley movement direction PM. However, the relationship between the flange part 62 and the pulley attachment part 95 is not restricted to the content illustrated by embodiment. For example, the outer side surface of the flange portion 62 of the modified example opposes the inner peripheral surface 95A of the pulley mounting portion 95 with a slight gap in a state where the drive pulley 40 is most moved in the approach direction PM1 of the pulley moving direction PM. Further, the outer surface of the flange portion 62 of the modified example opposes the inner peripheral surface 95A of the pulley mounting portion 95 with a slight gap in a state where the drive pulley 40 is most moved in the separation direction PM2 of the pulley movement direction PM.

  The drive pulley 40 of the embodiment includes a ball bearing 41 that supports the pulley body 50 in a state where the pulley body 50 can rotate with respect to the pulley housing 60. However, the configuration of the bearing that supports the pulley body 50 is not limited to the content exemplified in the embodiment. For example, the drive pulley 40 of the modified example has any of a roller bearing, a needle bearing, and a slide bearing instead of the ball bearing 41.

  In the vehicle 1 of the embodiment, the present steering device is applied to the rear wheel steering device 20. However, application of the present steering device is not limited to the content exemplified in the embodiment. For example, in the vehicle 1 according to the modification, the front wheel steering device 10 includes a rack parallel type steering device. And the vehicle 1 of a modification has the structure by which this steering apparatus is applied to the front wheel steering apparatus 10. FIG. Moreover, the vehicle 1 of another modification has a configuration in which the present steering device is applied to both the front wheel steering device 10 and the rear wheel steering device 20.

  The vehicle 1 of the embodiment includes a front wheel steering device 10 and a rear wheel steering device 20. However, the configuration of the vehicle 1 is not limited to the content exemplified in the embodiment. For example, the vehicle 1 of the modified example does not have the rear wheel steering device 20. In the vehicle 1 of the modified example, the front wheel steering device 10 has a rack parallel type steering device. The vehicle 1 of a modification has a configuration in which the present steering device is applied to the front wheel steering device 10.

  DESCRIPTION OF SYMBOLS 20 ... Rear wheel steering device (steering device), 21 ... Rear wheel rack shaft (rack shaft), 23 ... Rack housing (housing), 31 ... Electric motor, 31A ... Output shaft, 33 ... Belt, 34 ... Drive pulley, DESCRIPTION OF SYMBOLS 40 ... Drive pulley, 41 ... Ball bearing (bearing), 50 ... Pulley body, 60 ... Pulley housing, 62 ... Gutter, 70 ... Lock nut (fixed part), 80 ... Ball screw mechanism, 90 ... First housing, 95 ... pulley mounting part, 95A ... inner peripheral surface, 98 ... pulley insertion hole, 100 ... second housing, CP ... center of driving pulley, DH3 ... distance between the center of driving pulley and inner peripheral surface of pulley mounting part, MA: Long axis of the buttocks, ZA: Axial direction.

Claims (2)

An electric motor;
A drive pulley that rotates integrally with the output shaft of the electric motor;
A driven pulley that rotates as the drive pulley rotates through a belt;
A rack shaft that reciprocates in the axial direction;
A ball screw mechanism that reciprocates the rack shaft by rotating with the rotation of the driven pulley;
A housing to which the electric motor is mounted;
A fixing part for fixing the drive pulley to the housing;
The drive pulley includes a pulley body that is wound around the belt and rotates integrally with the output shaft, a pulley housing that is attached to the housing and accommodates a part of the pulley body, and the pulley body with respect to the pulley housing A bearing that supports the pulley body in a state in which the rotation of the pulley is possible,
The housing has a pulley insertion hole into which the pulley body is inserted,
The drive pulley is inserted into the pulley insertion hole in a state in which the drive pulley can approach or separate from the driven pulley ,
The pulley insertion hole is formed as a long hole in which the driving pulley can approach or separate from the driven pulley,
The pulley housing has a flange portion that is sandwiched between the housing and the fixed component,
The housing has a pulley mounting portion that accommodates the flange portion,
The outer shape of the collar is formed in an elliptical shape,
The long shaft of the flange portion is a steered device that is larger than twice the distance between the center of the drive pulley and the inner peripheral surface of the pulley mounting portion when the drive pulley is closest to the driven pulley . The long axis of the flange is orthogonal to the longitudinal direction of the pulley insertion hole.
The steering device according to claim 1 .