WO2022059384A1 - ステアリング装置 - Google Patents
ステアリング装置 Download PDFInfo
- Publication number
- WO2022059384A1 WO2022059384A1 PCT/JP2021/029469 JP2021029469W WO2022059384A1 WO 2022059384 A1 WO2022059384 A1 WO 2022059384A1 JP 2021029469 W JP2021029469 W JP 2021029469W WO 2022059384 A1 WO2022059384 A1 WO 2022059384A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- rack
- rack bar
- steering device
- inclined portion
- tooth
- Prior art date
Links
- 230000002093 peripheral effect Effects 0.000 claims description 12
- 230000033001 locomotion Effects 0.000 claims description 9
- 230000005489 elastic deformation Effects 0.000 claims description 8
- 239000007769 metal material Substances 0.000 claims description 5
- 238000004512 die casting Methods 0.000 claims description 3
- 238000005242 forging Methods 0.000 claims description 3
- 239000000463 material Substances 0.000 claims description 3
- 230000007547 defect Effects 0.000 description 9
- 238000005452 bending Methods 0.000 description 8
- 238000005266 casting Methods 0.000 description 3
- 241001247986 Calotropis procera Species 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 230000002950 deficient Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 239000013013 elastic material Substances 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 229920003051 synthetic elastomer Polymers 0.000 description 1
- 239000005061 synthetic rubber Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D3/00—Steering gears
- B62D3/02—Steering gears mechanical
- B62D3/12—Steering gears mechanical of rack-and-pinion type
- B62D3/126—Steering gears mechanical of rack-and-pinion type characterised by the rack
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H19/00—Gearings comprising essentially only toothed gears or friction members and not capable of conveying indefinitely-continuing rotary motion
- F16H19/02—Gearings comprising essentially only toothed gears or friction members and not capable of conveying indefinitely-continuing rotary motion for interconverting rotary or oscillating motion and reciprocating motion
- F16H19/04—Gearings comprising essentially only toothed gears or friction members and not capable of conveying indefinitely-continuing rotary motion for interconverting rotary or oscillating motion and reciprocating motion comprising a rack
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
- F16H55/02—Toothed members; Worms
- F16H55/26—Racks
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H57/00—General details of gearing
- F16H57/02—Gearboxes; Mounting gearing therein
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H57/00—General details of gearing
- F16H57/02—Gearboxes; Mounting gearing therein
- F16H57/032—Gearboxes; Mounting gearing therein characterised by the materials used
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H57/00—General details of gearing
- F16H57/02—Gearboxes; Mounting gearing therein
- F16H2057/02039—Gearboxes for particular applications
- F16H2057/02082—Gearboxes for particular applications for application in vehicles other than propelling, e.g. adjustment of parts
Definitions
- the present invention relates to a steering device.
- the steering device of Patent Document 1 has a cylindrical rack housing that movably accommodates the rack bar.
- This rack housing has a tubular portion extending in the moving direction of the rack bar, and a corner portion radially opposed to the outer peripheral portion of the rack bar is formed at the inner peripheral portion of the axial end portion of the tubular portion. Has been done.
- the present invention has been devised in view of the conventional circumstances, and one object of the present invention is to provide a steering device capable of suppressing a defect in the inner peripheral portion of a rack housing.
- the rack housing has a first inclined portion provided at the axial end portion of the tubular portion, and the first inclined portion is provided from the rack bar to the radial outer side of the rack bar. Tilt away. The first inclined portion comes into contact with the rack bar after the tubular portion when the rack bar is bent by an external input.
- FIG. 1 It is a schematic diagram of the steering apparatus of 1st Embodiment.
- (A) is a plan view of a rack bar
- (b) is a perspective view of the rack bar. It is sectional drawing of the rack bar cut along the line AA of FIG. 2 (a). It is sectional drawing of the rack bar in the rack housing cut along the line BB of FIG. It is a vertical sectional view of the rack bar and the rack housing cut along the line CC of FIG.
- (A) is a vertical cross-sectional view of the rack bar and the rack housing when the rack bar starts to bend in the direction of arrow X, and (b) is when the rack bar further bends in the direction of arrow X from the state of (a).
- a vertical sectional view of the rack bar and the rack housing according to the above, (c) is a vertical sectional view of the rack bar and the rack housing when the rack bar is further bent in the arrow X direction from the state of (b). It is a vertical sectional view of the rack bar and the rack housing of the prior art. It is a vertical sectional view of the rack bar and the rack housing of the second embodiment.
- FIG. 1 is a schematic view of the steering device of the first embodiment.
- a part of the steering device (outer part of the rack end) is shown in cross section.
- the steering device includes a steering mechanism 1 that transmits steering force from the driver and a steering assist mechanism 2 that assists the driver in steering operation.
- the steering mechanism 1 mechanically connects a steering wheel (not shown) arranged in the driver's cab of the vehicle and two steering wheels (not shown) which are the front wheels of the vehicle.
- the steering mechanism 1 has a steering shaft 5 having an input shaft 3 to which rotational force from the steering wheel is transmitted, an output shaft 4 connected to the input shaft 3 via a torsion bar (not shown), and steering thereof.
- a transmission mechanism 6 for transmitting the rotation of the shaft 5 to the steering wheel is provided.
- the transmission mechanism 6 is a rack & pinion mechanism (rack & pinion gear) including a pinion (not shown) provided on the outer periphery of the output shaft 4 and a rack tooth portion 20 provided on the outer periphery of the rack bar 7, which will be described later. It is composed of.
- the rack bar 7 is formed in a columnar shape made of a metal material, and is movably housed in an elongated cylindrical rack housing 8.
- the female threaded portion formed on the one end portion 7a of the rack bar 7 meshes with the male threaded portion of the first rack end 9, so that the first rack end 9 becomes the rack bar 7. It is fixed to one end 7a of the.
- the first rack end 9 has a concave portion 9a recessed in an arc shape, and the spherical end portion 10a of the first tie rod 10 is fitted into the concave portion 9a.
- the first ball joint 11 is configured by combining the recess 9a and the spherical end portion 10a, and the rack bar 7 and the first tie rod 10 are connected via the first ball joint 11. There is.
- the female threaded portion formed on the other end 7b of the rack bar 7 meshes with the male threaded portion of the second rack end 12, so that the second rack bar 7 is second.
- the rack end 12 is fixed to the other end 7b of the rack bar 7.
- the second rack end 12 has a recess 12a recessed in an arc shape, and the spherical end 13a of the second tie rod 13 is fitted into the recess 12a.
- the second ball joint 14 is configured by combining the recess 12a and the spherical end portion 13a, and the rack bar 7 and the second tie rod 13 are connected via the second ball joint 14. There is.
- the first tie rod 10 and the second tie rod 13 are connected to the corresponding steering wheel via a knuckle arm (not shown).
- the rack housing 8 is formed by die casting using a metal material such as aluminum. At both ends 8a and 8b in the axial direction of the rack housing 8, the impact due to the collision is alleviated when the first rack end 9 collides with the rack housing 8 and when the second rack end 12 collides with the rack housing 8. Each cushioning member may be provided.
- bellows-shaped boots 15 and 15 covering the outer periphery of the first ball joint 11 and the second ball joint 14 are installed at both ends 8a and 8b in the axial direction of the rack housing 8, respectively.
- the boot 15 is formed of an elastic material, for example, a synthetic rubber material so as to secure a predetermined flexibility, and prevents water, dust, etc. from entering the rack housing 8.
- mount brackets 16 for attaching the rack housing 8 to the vehicle body are provided in the vicinity of both ends 8a and 8b in the axial direction of the rack housing 8, respectively.
- a rubber bush (not shown) is installed on the mount bracket 16, and the rack housing 8 is attached to the vehicle body via the rubber bush.
- the steering assist mechanism 2 includes a motor 17, which is an electric motor that applies steering force to the steering mechanism 1, and the motor 17 is integrally configured with an electronic control unit (ECU) 18.
- the electronic control unit 18 has a function of storing and executing various control processes, and drives and controls the motor 17 based on a steering torque signal or the like from a torque sensor (not shown).
- the input shaft 3 rotates and the torsion bar is twisted, and the elastic force of the torsion bar generated by the rotation causes the output shaft 4 to rotate.
- the rotary motion of the output shaft 4 is converted into a linear motion along the axial direction of the rack bar 7 by the rack & pinion mechanism, and the knuckle arm (not shown) is pushed and pulled in the vehicle width direction via the tie rods 10 and 13. By doing so, the direction of the corresponding steering wheel is changed.
- FIG. 2A is a plan view of the rack bar 7, and FIG. 2B is a perspective view of the rack bar 7.
- FIG. 3 is a cross-sectional view of the rack bar 7 cut along the line AA of FIG. 2A.
- the line passing through the center of the rack bar 7 is defined as the "reference axis M”. Further, the direction parallel to the reference axis M and coincident with the moving direction of the rack bar 7 is defined as the "axial direction”, and the direction orthogonal to the reference axis M is defined as the "radial direction” with respect to the reference axis M. Further, the direction around the reference axis M is defined as the "circumferential direction”.
- the rack bar 7 is integrally formed of a metal material, and has a substantially semi-cylindrical rack main body 19 formed in a circumferential range opposite to the output shaft 4 with the reference axis M in between, and an output.
- a plurality of rack tooth portions 20 integrally formed with the rack main body 19 in a circumferential range facing the shaft 4, a columnar one end 7a integrally formed with one axial end of the rack main body 19, and a rack. It has a columnar other end portion 7b integrally formed at the other end in the axial direction of the main body portion 19.
- the rack main body 19 has a substantially semicircular shape when viewed from the axial direction, and has an outer edge portion 19a located at one end in the circumferential direction of a continuous arcuate outer peripheral portion and an outer peripheral portion. It has an outer edge portion 19b located at the other end in the circumferential direction of the above.
- the rack main body 19 has been shown to have a substantially semicircular shape when viewed from the axial direction, but the rack body 19 is not limited to the embodiment.
- the rack tooth portion 20 has a plurality of rack tooth portions 20 (31 in this embodiment) formed by forging a part of the circumferential region of the outer peripheral portion of the axial range excluding both end portions 7a and 7b. As shown in FIGS. 2A and 2B, the plurality of rack tooth portions 20 are arranged at equal intervals along the axial direction in the axial region between the both end portions 7a and 7b. As shown in FIG. 2A, each rack tooth portion 20 is slightly inclined toward one end portion 7a with respect to the reference axis M. That is, each rack tooth portion 20 is inclined so that the other end portion 20b of the rack tooth portion 20 in the tooth width direction is slightly located on the one end portion 7a side of the one end portion 20a in the tooth width direction.
- the rack tooth portion 20 has a substantially trapezoidal shape when viewed from the axial direction as shown in FIG.
- the rack tooth portion 20 has a tooth width direction one end portion 20a located at one end in the tooth width direction and a tooth width direction other end portion 20b located at the other end in the tooth width direction.
- the tooth width direction one end portion 20a includes a first inclined surface portion 20d inclined inward from one outer edge portion 19a of the rack main body portion 19 toward the tooth tip portion 20c side, and the first inclined surface portion. It has an arcuate first arcuate surface portion 20e that connects one end of the 20d and one end of the tooth tip portion 20c.
- the first inclined surface portion 20d and the first arc-shaped surface portion 20e have an outer circumference of the other end portion 7b (a part of the outer circumference is indicated by an arc-shaped solid line 7c and an arc-shaped broken line 7d, 7e). It is located on the outer side in the radial direction.
- the other end portion 20b in the tooth width direction has the same shape as the first inclined surface portion 20d, and the second inclined surface portion 20f inclined inward from the other outer edge portion 19b of the rack main body portion 19 toward the tooth tip portion 20c side.
- a second arcuate surface portion 20g having an arcuate surface shape similar to that of the first arcuate surface portion 20e and connecting one end of the second inclined surface portion 20f and the other end of the tooth tip portion 20c. ing.
- the second inclined surface portion 20f and the second arcuate surface portion 20g are located radially outside the outer periphery of the other end portion 7b described above.
- the tooth width (maximum tooth width) TW of the rack tooth portion 20 is the two intersection points C1 of the outer periphery of the other end portion 7b and the tooth tip portion 20c of the rack tooth portion 20 when viewed from the axial direction.
- the length of the line segment L connecting C2 is larger than the length L1 and is set to a length equal to or less than the diameter of the rack bar 7.
- the tooth width TW is substantially equal to the diameter of the rack bar 7.
- FIG. 4 is a cross-sectional view of the rack bar 7 in the rack housing 8 cut along the line BB of FIG.
- the outer peripheral portion of the rack housing 8 is simplified in order to clarify the figure.
- the rack housing 8 has a rack bar accommodating through hole 21b corresponding to the outer shape of the rack bar 7 in the central portion of the rack housing 8, and axially outward at both ends of the rack bar accommodating through hole 21b in the axial direction.
- a step portion 21 is provided so as to expand the step diameter.
- the inner peripheral surface of the rack bar accommodating through hole 21b is located at a portion facing the first arcuate surface portion 20e and the second arcuate surface portion 20g, and the rack bar 7 is input from the outside, for example, the road surface, from the rack main body portion 19 to the rack teeth. It has an arcuate first contact surface portion 21c and a second contact surface portion 21d that can be contacted with the first arcuate surface portion 20e and the second arcuate surface portion 20g when bent in the direction X toward the portion 20. ing.
- the radius of curvature of the first contact surface portion 21c and the second contact surface portion 21d is formed to be larger than the radius of curvature of the first arc-shaped surface portion 20e and the second arc-shaped surface portion 20g.
- the step portion 21 has an inner diameter that can receive the first rack end 9, and the bottom surface 21a of the step portion 21 is a regulatory surface that regulates the movement of the first ball joint 11 (see FIG. 1) along the axial direction.
- the width of the bottom surface 21a along the radial direction is such that the width BW1 of the portion where the first contact surface portion 21c and the second contact surface portion 21d are not provided is provided with the first contact surface portion 21c and the second contact surface portion 21d. It is formed so as to be wider than the widths BW2 and BW3 of the portions.
- the movement of the first ball joint 11 is not restricted directly by the bottom surface 21a of the stepped portion 21, but a cushioning member (not shown) that is housed in the stepped portion 21 and is provided so as to be in contact with the bottom surface 21a. It may be done indirectly through.
- FIG. 5 is a vertical cross-sectional view of the rack bar 7 and the rack housing 8 cut along the line CC of FIG.
- the first tilt angle ⁇ and the second tilt angle ⁇ are exaggerated and shown to be larger than the actual angles.
- the rack housing 8 has a cylindrical cylindrical portion 22 extending in the axial direction, a first inclined portion 23 provided at one end portion in the axial direction of the tubular portion 22, and an axial end portion of the first inclined portion 23. It has a second inclined portion 24 connected to the above.
- first racks the rack tooth portions facing the end of the inner side surface 22a adjacent to the first inclined portion 23 among the plurality of rack tooth portions 20 facing the tubular portion 22 in the radial direction are referred to as “first racks”. It is defined as “tooth portion 20A”. Further, the rack tooth portion that faces the first inclined portion 23 in the radial direction is defined as the “second rack tooth portion 20B”, and the rack tooth portion that faces the second inclined portion 24 in the radial direction is defined as the "third rack tooth portion”. It is defined as "20C”.
- the tubular portion 22, the first inclined portion 23, and the second inclined portion 24 are provided from the first to third rack tooth portions 20A, 20B, 20C when the rack bar 7 is bent in the arrow X direction due to the input from the road surface. It is provided on the premise that the stress received is dispersed step by step. That is, in the tubular portion 22, the first inclined portion 23 and the second inclined portion 24, when the rack bar 7 bends in the arrow X direction, the first rack tooth portion 20A first abuts on the tubular portion 22. Next, the second rack tooth portion 20B is provided so as to abut on the first inclined portion 23, and finally the third rack tooth portion 20C is provided so as to abut on the second inclined portion 24.
- the tubular portion 22 is located at the center of the rack housing 8 in the axial direction and extends along the axial direction.
- the tubular portion 22 has an inner side surface 22a formed by machining a cast surface, and the inner side surface 22a is parallel to the axial direction.
- the inner side surface 22a is provided on the first contact surface portion 21c and the second contact surface portion 21d (see FIG. 4) of the rack housing 8.
- the first inclined portion 23 has a first inclined inner side surface 23a that is inclined so as to move away from the rack bar 7 in the radial direction toward the outer side in the axial direction (one end 8a side in the axial direction).
- the first inclined portion 23 has a first inclined inner side surface 23a inclined so that the radial distance between the reference axis M and the first inclined portion 23 increases toward the outside in the axial direction.
- the first inclined inner side surface 23a is a casting surface formed when the rack housing 8 is die-cast.
- the first inclined inner side surface 23a is provided on the first contact surface portion 21c and the second contact surface portion 21d (see FIG. 4) of the rack housing 8.
- the first inclined inner side surface 23a is axially oriented at a first inclination angle ⁇ , which is an inferior angle among the angles formed between the inner side surface 22a of the tubular portion 22 parallel to the axial direction and the first inclined inner side surface 23a. It is inclined toward the outside.
- the first inclination angle ⁇ is set to the first arcuate surface portion 20e and the second arcuate surface portion of the first rack tooth portion 20A when the rack bar 7 bends in the elastic deformation region in the elastic deformation region due to the input from the road surface.
- the first arcuate surface portion 20e and the second arcuate surface portion 20g of the second rack tooth portion 20B are attached to the first inclined inner side surface 23a. It is set to an angle that allows contact.
- the first inclination angle ⁇ is 7 °.
- first inclined inner side surface 23a and the inner side surface 22a are interposed via a first arcuate surface 25 having an arcuate shape that swells toward the rack bar 7 when viewed in a cross section along the axial direction as shown in FIG. Are smoothly connected to each other.
- the second inclined portion 24 has a second inclined inner side surface 24a inclined so as to be separated radially outward at a second inclined angle ⁇ larger than the first inclined angle ⁇ of the first inclined portion 23.
- the second inclination angle ⁇ is set to the first arcuate surface portion 20e and the second arcuate surface portion of the second rack tooth portion 20B when the rack bar 7 bends in the elastic deformation region in the elastic deformation region due to the input from the road surface. After 20 g (see FIG. 4) abuts on each of the first inclined inner side surfaces 23a, the first arcuate surface portion 20e and the second arcuate surface portion 20 g of the third rack tooth portion 20C abut on each second inclined inner side surface 24a. It is set to a possible angle.
- the second inclination angle ⁇ is 11 °.
- the second inclined inner side surface 24a is a casting surface formed when the rack housing 8 is die-cast.
- the second inclined inner side surface 24a is provided on the first contact surface portion 21c and the second contact surface portion 21d (see FIG. 4) of the rack housing 8.
- the second inclined inner side surface 24a and the first inclined inner side surface 23a form a second arcuate surface that swells toward the rack bar 7 when viewed in a cross section along the axial direction as shown in FIG. They are smoothly connected to each other via 26.
- the corner portion 24b provided between the second inclined inner side surface 24a and the bottom surface 21a of the step portion 21 is formed with an R chamfered portion 24c curved in an arcuate shape.
- the pitch P of the rack tooth portion 20 is the axial width D1 and the first axial width D1 of the first inclined inner side surface 23a along the axial direction. 2 It is shorter than the axial width D2 of the inclined inner side surface 24a.
- the pitch P is shorter than the axial widths D1 and D2 as described above, as shown in FIG. 5, the tooth thickness t of the first arcuate surface portion 20e along the axial direction is smaller than the axial widths D1 and D2.
- the second rack tooth portion 20B and the third rack tooth portion 20C are likely to come into contact with the first inclined inner side surface 23a and the second inclined inner side surface 24a.
- FIG. 6A is a vertical cross-sectional view of the rack bar 7 and the rack housing 8 when the rack bar 7 begins to bend in the direction of arrow X.
- FIG. 6B is a vertical cross-sectional view of the rack bar 7 and the rack housing 8 when the rack bar 7 is further bent in the arrow X direction from the state of FIG. 6A.
- FIG. 6 (c) is a vertical cross-sectional view of the rack bar 7 and the rack housing 8 when the rack bar 7 is further bent in the arrow X direction from the state of FIG. 6 (b).
- the first arcuate surface portion 20e of the third rack tooth portion 20C abuts on the second inclined inner side surface 24a, so that the stress acting from the rack bar 7 to the rack housing 8 is applied to the inner side surface 22a and the first inclined inner surface surface. It is dispersed in 23a and the second inclined inner side surface 24a.
- FIG. 7 is a vertical sectional view of the rack bar 7 and the rack housing 8 of the prior art.
- the corner portion 27 is located at the inner peripheral portion of the axial end portion of the tubular portion 22 of the rack housing 8. It is provided.
- the corner portion 27 has an angle of 90 ° when viewed in an axial cross section, and is a portion where stress is more likely to be concentrated than other portions of the tubular portion 22. There is.
- the corner portion 27 may be damaged due to the stress concentration.
- the first inclined inner side surface 23a of the first inclined portion 23 has the first rack tooth portion 20A and the cylinder when the rack bar 7 is bent in the arrow X direction by the input from the road surface.
- the contact with the second rack tooth portion 20B is performed after the contact with the inner side surface 22a of the shaped portion 22.
- the stress acting on the rack housing 8 from the rack bar 7 is dispersed to the inner side surface 22a and the first inclined inner side surface 23a.
- the inner side surface 22a absorbs the stress acting on the rack housing 8 from the rack bar 7, and then a smaller stress acts on the first inclined inner side surface 23a. Therefore, it is possible to suppress the occurrence of a defect in the inner surface of the rack housing 8 as compared with the case where an excessive stress acts directly only on the inner surface 22a.
- the rack is loaded from the connection point between the first tie rod 10 and the rack bar 7 as compared with the case where the stress is received only by the inner side surface 22a.
- the distance between the bar 7 and the rack housing 8 to the contact point is shortened. More specifically, the distance from the connection point between the first tie rod 10 and the rack bar 7 to the contact point between the first inclined inner side surface 23a and the second rack tooth portion 20B is the distance between the first tie rod 10 and the rack bar 7. It is shorter than the distance from the connection point to the contact point between the inner side surface 22a and the first rack tooth portion 20A.
- the bending moment acting on the rack bar 7 is the distance from the connection point between the first tie rod 10 and the rack bar 7 to the contact point between the rack bar 7 and the rack housing 8, and the bending direction of the rack bar 7, that is, the arrow X. It is the product of the force acting in the direction. Therefore, the bending moment acting on the rack bar 7 is from the connection point between the first tie rod 10 and the rack bar 7 to the contact point between the rack bar 7 and the rack housing 8 if the force acting in the arrow X direction is constant. The shorter the distance, the smaller.
- the bending moment acting on the rack bar 7 becomes smaller as compared with the case where the stress is received only by the inner side surface 22a. , The bending stress acting on the rack bar 7 is also reduced. Therefore, the durability of the rack bar 7 with respect to the contact with the rack housing 8 can be improved.
- the second inclined portion 24 has a second inclined inner side surface 24a that is inclined at an inclination angle larger than that of the first inclined inner side surface 23a in the axial direction, and the second inclined inner surface surface.
- the 24a is in contact with the third rack tooth portion 20C when the rack bar 7 is bent in the arrow X direction due to the input from the road surface.
- the second inclined inner side surface 24a is in contact with the third rack tooth portion. It is in contact with the portion 20C.
- the stress acting on the rack housing 8 from the rack bar 7 is dispersed to the inner side surface 22a, the first inclined inner side surface 23a, and the second inclined inner side surface 24a. Therefore, it is possible to more effectively suppress the occurrence of defects on the inner surface of the rack housing 8 as compared with the case where stress acts on the inner surface 22a and the first inclined inner surface 23a.
- the stress from the rack bar 7 is received by the inner side surface 22a, the first inclined inner side surface 23a and the second inclined inner side surface 24a, the stress is applied by the inner side surface 22a and the first inclined inner side surface 23a.
- the distance from the connection point between the tie rod 10 and the rack bar 7 to the contact point between the rack bar 7 and the rack housing 8 is shortened. More specifically, the distance from the connection point between the first tie rod 10 and the rack bar 7 to the contact point between the second inclined inner surface surface 24a and the third rack tooth portion 20C is the distance between the first tie rod 10 and the rack bar 7. It is shorter than the distance from the connection point to the contact point between the first inclined inner side surface 23a and the second rack tooth portion 20B. Therefore, the bending moment acting on the rack bar 7 is further reduced, and thereby the bending stress acting on the rack bar 7 is further reduced. Therefore, the durability of the rack bar 7 with respect to the contact with the rack housing 8 can be further improved.
- the tooth width TW of the rack tooth portion 20 connects two intersections C1 and C2 between the outer periphery of the other end portion 7b and the tooth tip portion 20c of the rack tooth portion 20 when viewed from the axial direction. It is larger than the length L1 of the line segment L.
- the tooth width TW of the rack tooth portion 20 is set relatively wide in this way, a large number of rack tooth portions 20 that mesh with the pinion of the output shaft 4 at the same time is secured. Therefore, the load received by one rack tooth portion 20 becomes small, which improves the durability of the rack tooth portion 20.
- the inner side surface 22a, the first inclined inner side surface 23a, and the second inclined inner side surface 24a are the first to third racks when the rack bar 7 is bent in the arrow X direction by the input from the road surface.
- the tooth portions 20A, 20B, and 20C are in contact with one end portion 20a in the tooth width direction and the other end portion 20b in the tooth width direction. Therefore, the stress acting on the rack housing 8 from the rack bar 7 is dispersed at two points, one end portion 20a in the tooth width direction and the other end portion 20b in the tooth width direction. Therefore, it becomes difficult for the stress to act locally from the rack bar 7 to a part of the rack housing 8 as compared with the case where the stress is received at one point. Therefore, it is possible to further suppress the occurrence of defects in the inner side surface 22a, the first inclined inner side surface 23a, and the second inclined inner side surface 24a of the rack housing 8.
- the width of the bottom surface 21a along the radial direction is such that the width BW1 of the portion where the first contact surface portion 21c and the second contact surface portion 21d are not provided is the first contact surface portion 21c and the second. It is formed so as to be wider than the widths BW2 and BW3 of the portion where the contact surface portion 21d is provided.
- the width of the bottom surface 21a which is the regulation surface along the radial direction of the rack bar 7, is the width of the portion where the second inclined portion 24 is not provided, and the width BW1 of the portion where the second inclined portion 24 is provided. It is formed so as to be wider than the widths BW2 and BW3.
- both ends 20a and 20b of the rack tooth portion 20 in the tooth width direction are formed in an arcuate shape. That is, one end portion 20a in the tooth width direction and the other end portion 20b in the tooth width direction have an arcuate first arcuate surface portion 20e and a second arcuate surface portion 20g. Then, the first arcuate surface portion 20e and the second arcuate surface portion 20g come into contact with the arcuate surface-shaped first contact surface portion 21c and the second contact surface portion 21d. Therefore, the first arcuate surface portion 20e and the second arcuate surface portion 20g come into surface contact with the first contact surface portion 21c and the second contact surface portion 21d.
- the second inclined inner side surface 24a has the third rack tooth after the contact of the first inclined inner surface 23a when the rack bar 7 is bent in the arrow X direction by the input from the road surface. It comes into contact with the portion 20C. More specifically, the inner side surface 22a and the first inclined inner side surface 23a absorb the stress acting on the rack housing 8 from the rack bar 7, and then a smaller stress acts on the second inclined inner side surface 24a. As a result, when the excessive stress acts directly on the second inclined inner side surface 24a without passing through the contact between the first and second rack tooth portions 20A and 20B and the inner side surface 22a and the first inclined inner side surface 23a. In comparison, the stress acting on the corner portion 24b provided on one end side in the axial direction of the second inclined inner side surface 24a can be reduced, and the loss of the corner portion 24b can be suppressed.
- the inner surface 22a and the first inclined inner surface 23a are connected to each other via the first arc surface 25 forming an arc surface, and the first inclined inner surface 23a and the second inclined inner surface 24a are connected to each other. Are connected to each other via a second arcuate surface 26 forming an arcuate surface. If the inner side surface 22a and the first inclined inner side surface 23a and the first inclined inner side surface 23a and the second inclined inner side surface 24a are connected by a corner portion, the second rack tooth portion 20B and the third rack tooth The portion 20C may be damaged due to contact with the corner portion.
- the pitch P of the rack tooth portion 20 is shorter than the axial width D1 of the first inclined inner side surface 23a along the axial direction.
- the tooth thickness t of the first arcuate surface portion 20e along the axial direction is shorter than the axial width D1 of the first inclined inner side surface 23a along the axial direction. Therefore, when the first arcuate surface portion 20e of the second rack tooth portion 20B abuts on the wide first inclined inner side surface 23a, the stress from the second rack tooth portion 20B is reliably transmitted by the first inclined inner surface portion 23a. Tooth. As a result, it is possible to improve the distribution of stress to the first inclined portion 23 and suppress the defect of the first inclined portion 23.
- the pitch P of the rack tooth portion 20 is shorter than the axial width D2 of the second inclined inner side surface 24a along the axial direction. Therefore, as in the case of the first inclined inner side surface 23a, the stress from the third rack tooth portion 20C is caused by the first arcuate surface portion 20e of the third rack tooth portion 20C coming into contact with the wide second inclined inner side surface 24a. Is reliably transmitted by the second inclined inner side surface 24a. As a result, it is possible to improve the distribution of stress to the second inclined portion 24 and suppress the defect of the second inclined portion 24, particularly the corner portion 24b.
- the rack bar 7 abuts on the second inclined inner side surface 24a within the elastic deformation region of the rack bar 7. If the rack bar 7 abuts on the second inclined inner surface 24a in the plastic deformation region, the rack bar 7 abuts on the second inclined inner surface as compared with the case where the rack bar 7 abuts in the elastic deformation region. There is a risk of strongly abutting on the 24a and damaging the second inclined inner side surface 24a and the corner portion 24b. Therefore, in the present embodiment, damage to the second inclined inner side surface 24a and the like can be suppressed by keeping the rack bar 7 in contact with the elastic deformation region.
- the first inclined inner surface 23a has a cast surface. If the first inclined inner side surface 23a is machined, cavities may remain on the first inclined inner side surface 23a, and the cavities may reduce the strength of the first inclined inner side surface 23a. Therefore, in the present embodiment, by using the first inclined inner side surface 23a as the casting surface, it is possible to suppress a decrease in the strength of the first inclined inner side surface 23a.
- FIG. 8 is a vertical sectional view of the rack bar 7 and the rack housing 8 of the second embodiment.
- the tubular portion 22, the first inclined portion 23, and the second inclined portion 24 change in a curved shape along the axial direction. More specifically, as shown in FIG. 8, the linear inner side surface 22a is slightly recessed in an arc shape toward the first inclined portion 23 via the first arc surface 25, and the first inclined portion arc surface 23b. The first inclined portion arc surface 23b is connected to the second inclined portion arc surface 24d recessed on the second inclined portion 24 side via the second arc surface 26.
- the inner side surface 22a of the tubular portion 22, the first inclined portion arc surface 23b of the first inclined portion 23, and the second inclined portion arc surface 24d of the second inclined portion 24 are curved in the axial direction. It has changed to. Therefore, the bulge of the second arc surface 26, which is the change point of the inclination angle between the first inclined portion arc surface 23b and the second inclined portion arc surface 24d, becomes small. As a result, the stress concentration on the second arc surface 26 when the second rack tooth portion 20B comes into contact with the input from the road surface is relaxed. Therefore, it is possible to suppress the defect of the second arc surface 26.
- the steering device based on the embodiment described above, for example, the one described below can be considered.
- the steering device is, as one aspect, a rack housing formed of a steering shaft to which rotational force is transmitted, a rack bar that meshes with the steering shaft, and a metal material, and movably accommodates the rack bar.
- a tubular portion extending along the moving direction of the rack bar, and a first inclined portion provided at the axial end of the tubular portion and inclined away from the rack bar in the radial direction of the rack bar.
- the tubular portion abuts on the rack bar when the rack bar is bent by an external input, and the first inclined portion is bent by the rack bar due to an external input.
- the rack housing is provided, which comes into contact with the rack bar after the tubular portion.
- the rack housing is connected to the first tilted portion and tilts away from the rack bar radially outward at a larger tilt angle than the first tilted portion.
- a second inclined portion is further provided, and the second inclined portion comes into contact with the rack bar when the rack bar is bent by an external input.
- the rack bar is formed by forging a portion of the circumferential region at the outer periphery of the axial range excluding the ends of the columnar material. It has a plurality of rack tooth portions, and the first inclined portion is formed at a position facing one of the plurality of rack tooth portions.
- the tooth width of the rack tooth portion is the outer circumference of the end portion and the tooth tip portion of the rack tooth portion when viewed from the moving direction of the rack bar. It is longer than the length of the line segment connecting the two intersections with.
- the tubular portion, the first tilted portion and the second tilted portion are racks when the rack bar is bent by an external input. It abuts on both ends of the tooth in the tooth width direction.
- the rack bar is connected to a ball joint and the rack housing is located adjacent to the second tilt portion in the direction of movement of the rack bar.
- a step portion having a bottom surface serving as a restricting surface for restricting the movement of the ball joint along the movement direction of the rack bar is provided, and the width of the bottom surface along the radial direction of the rack bar is the second.
- the width of the portion where the inclined portion is not provided is formed to be wider than the width of the portion where the second inclined portion is provided.
- both ends of each rack tooth portion in the tooth width direction are formed in an arcuate shape.
- the second tilted portion is with the rack bar after the first tilted portion when the rack bar is bent by an external input. Contact.
- the tubular portion and the first inclined portion are connected to each other via a first arc plane forming an arc surface, and the first inclined portion is formed.
- the second inclined portion are connected to each other via a second arc plane forming an arc plane.
- the tubular portion, the first inclined portion and the second inclined portion change in a curved shape.
- the pitch of the rack teeth is shorter than the axial width of the first inclined portion along the moving direction of the rack bar.
- the pitch of the rack teeth is shorter than the axial width of the second inclined portion along the moving direction of the rack bar.
- the rack bar abuts on the second tilted portion within the elastically deformed region of the rack bar.
- the rack housing is formed by die casting and the first inclined portion has a cast surface.
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- General Engineering & Computer Science (AREA)
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Abstract
Description
(ステアリング装置の構成)
図1は、第1の実施形態のステアリング装置の概略図である。図1では、ステアリング装置の一部(ラックエンドの外側部分)を断面で示してある。
[第1の実施形態の効果]
図7は、従来技術のラックバー7およびラックハウジング8の縦断面図である。
図8は、第2の実施形態のラックバー7およびラックハウジング8の縦断面図である。
第2の実施形態では、筒状部22の内側面22a、第1傾斜部23の第1傾斜部円弧面23bおよび第2傾斜部24の第2傾斜部円弧面24dは、軸方向にわたって曲線状に変化している。このため、第1傾斜部円弧面23bと第2傾斜部円弧面24dとの傾斜角度の変化点となる第2円弧面26の膨らみが小さくなる。これにより、路面からの入力に伴い第2ラック歯部20Bが当接したときの第2円弧面26への応力集中が緩和される。よって、第2円弧面26の欠損を抑制することができる。
Claims (14)
- 回転力が伝達される操舵軸と、
前記操舵軸と噛み合うラックバーと、
金属材料で形成され、前記ラックバーを移動可能に収容するラックハウジングであって、
前記ラックバーの移動方向に沿って延びる筒状部と、該筒状部の軸方向端部に設けられ、前記ラックバーから前記ラックバーの径方向外側に離れるように傾斜する第1傾斜部と、を有し、
前記筒状部は、前記ラックバーが外部からの入力により撓んだときに前記ラックバーと当接し、
前記第1傾斜部は、前記ラックバーが外部からの入力により撓んだときに、前記筒状部よりも後に前記ラックバーと当接する、前記ラックハウジングと、
を備えるステアリング装置。 - 請求項1に記載のステアリング装置において、
前記ラックハウジングは、前記第1傾斜部に接続され、前記第1傾斜部よりも大きな傾斜角度で前記ラックバーから前記ラックバーの径方向外側に離れるように傾斜する第2傾斜部をさらに備え、
前記第2傾斜部は、前記ラックバーが外部からの入力により撓んだときに前記ラックバーと当接することを特徴とするステアリング装置。 - 請求項2に記載のステアリング装置において、
前記ラックバーは、円柱状の素材の端部を除く軸方向範囲の外周部における一部の周方向領域を鍛造することにより形成された複数のラック歯部を有し、
前記第1傾斜部は、前記複数のラック歯部のうちの1つと対向する位置に形成されていることを特徴とするステアリング装置。 - 請求項3に記載のステアリング装置において、
前記ラック歯部の歯幅は、前記ラックバーの移動方向から見たときの前記端部の外周と前記ラック歯部の歯先部との2つの交点を結ぶ線分の長さよりも大きいことを特徴とするステアリング装置。 - 請求項3に記載のステアリング装置において、
前記筒状部、前記第1傾斜部および前記第2傾斜部は、前記ラックバーが外部からの入力により撓んだときに各ラック歯部の歯幅方向両端部と当接することを特徴とするステアリング装置。 - 請求項5に記載のステアリング装置において、
前記ラックバーは、ボールジョイントに接続され、
前記ラックハウジングは、前記ラックバーの移動方向において前記第2傾斜部と隣接した位置に、前記ラックバーの移動方向に沿った前記ボールジョイントの移動を規制する規制面となる底面を有した段部を備えており、
前記ラックバーの径方向に沿った前記底面の幅は、前記第2傾斜部が設けられていない箇所の幅が前記第2傾斜部が設けられている箇所の幅よりも広くなるように形成されていることを特徴とするステアリング装置。 - 請求項5に記載のステアリング装置において、
各ラック歯部の歯幅方向両端部が円弧面状に形成されていることを特徴とするステアリング装置。 - 請求項3に記載のステアリング装置において、
前記第2傾斜部は、前記ラックバーが外部からの入力により撓んだときに、前記第1傾斜部よりも後に前記ラックバーと当接することを特徴とするステアリング装置。 - 請求項8に記載のステアリング装置において、
前記筒状部と前記第1傾斜部とは、円弧面状をなす第1円弧面を介して互いに接続され、
前記第1傾斜部と前記第2傾斜部とは、円弧面状をなす第2円弧面を介して互いに接続されていることを特徴とするステアリング装置。 - 請求項3に記載のステアリング装置において、
前記筒状部、前記第1傾斜部および前記第2傾斜部は、曲線状に変化することを特徴とするステアリング装置。 - 請求項3に記載のステアリング装置において、
前記ラック歯部のピッチは、前記ラックバーの移動方向に沿った前記第1傾斜部の軸方向幅よりも短いことを特徴とするステアリング装置。 - 請求項11に記載のステアリング装置において、
前記ラック歯部のピッチは、前記ラックバーの移動方向に沿った前記第2傾斜部の軸方向幅よりも短いことを特徴とするステアリング装置。 - 請求項3に記載のステアリング装置において、
前記ラックバーは、該ラックバーの弾性変形領域内で前記第2傾斜部と当接することを特徴とするステアリング装置。 - 請求項1に記載のステアリング装置において、
前記ラックハウジングは、ダイカスト鋳造により形成され、
前記第1傾斜部は鋳肌面を有することを特徴とするステアリング装置。
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CN202180063170.2A CN116507548A (zh) | 2020-09-17 | 2021-08-10 | 转向装置 |
JP2022550409A JP7488905B2 (ja) | 2020-09-17 | 2021-08-10 | ステアリング装置 |
US18/044,330 US20230331288A1 (en) | 2020-09-17 | 2021-08-10 | Steering device |
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JP2020-156060 | 2020-09-17 | ||
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PCT/JP2021/029469 WO2022059384A1 (ja) | 2020-09-17 | 2021-08-10 | ステアリング装置 |
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US (1) | US20230331288A1 (ja) |
JP (1) | JP7488905B2 (ja) |
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Citations (4)
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JP2017007420A (ja) * | 2015-06-18 | 2017-01-12 | 日本精工株式会社 | ラックアンドピニオン式ステアリングギヤユニット及び滑り軸受の製造方法 |
WO2019049477A1 (ja) * | 2017-09-07 | 2019-03-14 | 日本精工株式会社 | ラックおよびその製造方法、並びに、操舵装置、車両、および、ラックの予備成形用金型 |
JP2019077250A (ja) * | 2017-10-20 | 2019-05-23 | 株式会社ジェイテクト | ステアリング装置 |
US20200172151A1 (en) * | 2018-11-30 | 2020-06-04 | Steering Solutions Ip Holding Corporation | Steering system rack with flattened portion |
-
2021
- 2021-08-10 US US18/044,330 patent/US20230331288A1/en active Pending
- 2021-08-10 WO PCT/JP2021/029469 patent/WO2022059384A1/ja active Application Filing
- 2021-08-10 CN CN202180063170.2A patent/CN116507548A/zh active Pending
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JP2017007420A (ja) * | 2015-06-18 | 2017-01-12 | 日本精工株式会社 | ラックアンドピニオン式ステアリングギヤユニット及び滑り軸受の製造方法 |
WO2019049477A1 (ja) * | 2017-09-07 | 2019-03-14 | 日本精工株式会社 | ラックおよびその製造方法、並びに、操舵装置、車両、および、ラックの予備成形用金型 |
JP2019077250A (ja) * | 2017-10-20 | 2019-05-23 | 株式会社ジェイテクト | ステアリング装置 |
US20200172151A1 (en) * | 2018-11-30 | 2020-06-04 | Steering Solutions Ip Holding Corporation | Steering system rack with flattened portion |
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JPWO2022059384A1 (ja) | 2022-03-24 |
CN116507548A (zh) | 2023-07-28 |
JP7488905B2 (ja) | 2024-05-22 |
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