WO2020004037A1 - Réducteur et dispositif de direction assistée - Google Patents

Réducteur et dispositif de direction assistée Download PDF

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Publication number
WO2020004037A1
WO2020004037A1 PCT/JP2019/023278 JP2019023278W WO2020004037A1 WO 2020004037 A1 WO2020004037 A1 WO 2020004037A1 JP 2019023278 W JP2019023278 W JP 2019023278W WO 2020004037 A1 WO2020004037 A1 WO 2020004037A1
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WO
WIPO (PCT)
Prior art keywords
bearing
raceway groove
speed reducer
drive gear
outer ring
Prior art date
Application number
PCT/JP2019/023278
Other languages
English (en)
Japanese (ja)
Inventor
貴也 柳生
Original Assignee
Ｋｙｂ株式会社
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Filing date
Publication date
Application filed by Ｋｙｂ株式会社 filed Critical Ｋｙｂ株式会社
Publication of WO2020004037A1 publication Critical patent/WO2020004037A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • 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
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/02—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows
    • F16C19/04—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for radial load mainly
    • F16C19/06—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for radial load mainly with a single row or balls
    • 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
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C25/00—Bearings for exclusively rotary movement adjustable for wear or play
    • F16C25/06—Ball or roller bearings
    • F16C25/08—Ball or roller bearings self-adjusting
    • 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
    • F16H1/00—Toothed gearings for conveying rotary motion
    • F16H1/02—Toothed gearings for conveying rotary motion without gears having orbital motion
    • F16H1/04—Toothed gearings for conveying rotary motion without gears having orbital motion involving only two intermeshing members
    • F16H1/12—Toothed gearings for conveying rotary motion without gears having orbital motion involving only two intermeshing members with non-parallel axes
    • F16H1/16—Toothed gearings for conveying rotary motion without gears having orbital motion involving only two intermeshing members with non-parallel axes comprising worm and worm-wheel
    • 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
    • F16H57/021—Shaft support structures, e.g. partition walls, bearing eyes, casing walls or covers with bearings
    • F16H57/022—Adjustment of gear shafts or bearings

Definitions

  • the present invention relates to a speed reducer and a power steering device.
  • the worm speed reducer includes a worm shaft that is rotationally driven by a drive source such as an electric motor, and a worm wheel that meshes with the worm shaft. Both ends of the worm shaft are rotatably supported by bearings.
  • the base end of the worm shaft is swingably connected to the rotating shaft of the electric motor, and the distal end of the worm shaft is urged toward the worm wheel by the urging member.
  • the bearing supporting the base end of the worm shaft is provided with an internal clearance so that the inner ring can swing with respect to the outer ring.
  • the bearing is provided with the internal clearance, when an axial force acts on the worm shaft, the inner ring moves slightly in the axial direction together with the worm shaft, so that the rolling element (ball) is moved to the outer ring.
  • noise collision sound
  • the present invention aims to reduce the noise of the speed reducer.
  • a speed reducer including a drive gear shaft connected to a drive source, and a driven gear meshing with the drive gear shaft, wherein a base end side of the drive gear shaft is rotatable.
  • a first bearing for supporting, a second bearing for rotatably supporting the distal end side of the drive gear shaft, and an urging member for urging the drive gear shaft toward the driven gear via the second bearing.
  • the first bearing comprises: an inner ring having an inner raceway groove; an outer ring having an outer raceway groove; and a plurality of rolling elements disposed between the inner raceway groove and the outer raceway groove.
  • a distance between the inner raceway groove and the outer raceway groove in a first direction which is a direction in which the drive gear shaft swings, and in a second direction orthogonal to each of the axial directions of the drive gear shaft, The distance between the inner raceway groove and the outer raceway groove in the first direction; It is also small.
  • a speed reducer including a drive gear shaft connected to a drive source, and a driven gear meshing with the drive gear shaft, wherein a base end side of the drive gear shaft is rotatable.
  • a second bearing rotatably supporting the distal end side of the drive gear shaft, and a bias for biasing the drive gear shaft toward the driven gear via the second bearing.
  • the pressing portion sets a direction in which the drive gear shaft swings as a first direction, and includes a first direction and an axial direction of the drive gear shaft.
  • a direction orthogonal to each is defined as a second direction, the second direction with respect to the first bearing Pressure, the to be larger than the pressing force of the first direction relative to the first bearing, to press the outer ring of the first bearing.
  • a power steering device including the speed reducer and an electric motor serving as the drive source, wherein the driven gear is provided on a rack shaft that steers a wheel.
  • the speed reducer is provided on an output shaft that transmits a rotational force of a motor, and reduces the rotation of the drive gear shaft and transmits the rotation to the driven gear.
  • FIG. 1 is a configuration diagram of a power steering device including a speed reducer according to a first embodiment of the present invention.
  • FIG. 2 is a cross-sectional view of a power steering device including the speed reducer according to the first embodiment of the present invention.
  • FIG. 3A is a schematic cross-sectional view of the bearing, showing a state where the inner ring is not inclined with respect to the outer ring.
  • FIG. 3B is a schematic cross-sectional view of the bearing, showing a state where the inner ring is inclined with respect to the outer ring.
  • FIG. 4 is a perspective view of the speed reducer with a gear case partially cut away.
  • FIG. 5 is a schematic sectional view of the speed reducer taken along line VV in FIG. FIG.
  • FIG. 6 is a schematic cross-sectional view of the inner ring and the outer ring of the first bearing along the line VI-VI in FIGS. 7 and 8.
  • FIG. 7 is a schematic sectional view of the first bearing taken along line VII-VII in FIG.
  • FIG. 8 is a schematic sectional view of the first bearing taken along line VIII-VIII in FIG.
  • FIG. 9 is a schematic sectional view of a speed reducer according to a second embodiment of the present invention.
  • FIG. 10 is a diagram illustrating a pressing ring used in a speed reducer according to a second embodiment of the present invention.
  • FIG. 11 is a diagram illustrating a pressing ring deformed by press-fitting a bearing.
  • FIG. 12 is a schematic cross-sectional view illustrating a pressing portion provided in a housing hole of a speed reducer according to a modification.
  • a power steering device including a speed reducer according to a first embodiment of the present invention will be described with reference to the drawings.
  • a power steering device is a device that is mounted on a vehicle and assists a steering force applied by a driver to a steering wheel.
  • the power steering device 10 includes a speed reducer 100 and an electric motor 7 as a drive source.
  • the speed reducer 100 is connected to an output shaft 7 a of the electric motor 7 and meshes with a worm shaft 2 as a drive gear shaft that rotates with the driving of the electric motor 7, and a worm 2 a as a drive gear formed on the worm shaft 2.
  • the worm wheel 1 includes a worm wheel 1 as a driven gear, a gear case 3 that is a case that houses the worm shaft 2 and the worm wheel 1, and a shaft support structure 101 that supports the worm shaft 2.
  • the worm shaft 2 and the output shaft 7a of the electric motor 7 are connected by a shaft connecting device 19 that allows a shaft deviation.
  • a steering shaft 20 is connected to the steering wheel 16, and the steering shaft 20 rotates with the rotation of the steering wheel 16.
  • the steering shaft 20 includes an input shaft 21 linked to the steering wheel 16, an output shaft 22 linked to the rack shaft 8, and a torsion bar 23 connecting the input shaft 21 and the output shaft 22.
  • the worm wheel 1 is provided on the output shaft 22.
  • the power steering device 10 includes a torque sensor 24 that detects a steering torque acting on a torsion bar 23 by a relative rotation between an input shaft 21 and an output shaft 22 caused by a driver's steering operation, and a steering detected by the torque sensor 24.
  • a controller that controls the driving of the electric motor based on the torque.
  • the torque output from the electric motor 7 is transmitted from the worm shaft 2 to the worm wheel 1 and applied to the output shaft 22 as assist torque.
  • the power steering device 10 assists the driver in steering by controlling the driving of the electric motor 7 by the controller 25 based on the detection result of the torque sensor 24.
  • the speed reducer 100 reduces the rotation of the worm shaft 2 and transmits the rotation to the worm wheel 1.
  • the output shaft 22 provided with the worm wheel 1 transmits the torque of the electric motor 7 to the rack shaft 8 that steers the wheels 6.
  • the worm shaft 2 is housed in a metal gear case 3, and the electric motor 7 is attached to the gear case 3.
  • the worm 2a is formed with teeth 2e that mesh with the teeth 1a of the worm wheel 1.
  • An opening 3c is formed in the gear case 3 at a position corresponding to the tooth 2e, and the tooth 2e of the worm 2a and the tooth 1a of the worm wheel 1 mesh with each other through the opening 3c.
  • the shaft support structure 101 of the speed reducer 100 includes a first bearing 4 that rotatably supports the base end side (the electric motor 7 side) of the worm shaft 2 and a distal end side (the side opposite to the electric motor 7 side) of the worm shaft 2. ), And a coil spring 12 as an urging member for urging the worm shaft 2 toward the worm wheel 1 via the second bearing 11.
  • the worm shaft 2 is rotatably supported in the gear case 3 by a pair of bearings (a first bearing 4 and a second bearing 11).
  • the axial direction (center axis direction) of the worm shaft 2 is also simply referred to as the axial direction (D3).
  • the first bearing 4 is a deep groove ball bearing in which a ball (ball) 143 as a rolling element is interposed between the annular outer ring 141 and the inner ring 142.
  • the first bearing 4 is housed in a housing hole 130 provided in the gear case 3.
  • the outer ring 141 of the first bearing 4 is held in the axial direction (D3) between the stepped portion 3a formed in the gear case 3 and the lock nut 5 fastened in the gear case 3.
  • the inner ring 142 of the first bearing 4 is fixed by being pressed into the worm shaft 2.
  • the inner ring 142 is sandwiched in the axial direction (D3) between the step portion 2b of the worm shaft 2 and the worm-side joint 9 of the shaft coupler 19 that is press-fitted into the end of the worm shaft 2.
  • the first bearing 4 has an internal clearance 144 (see FIG. 7) for allowing the worm shaft 2 to swing toward the worm wheel 1.
  • a first direction in which the worm shaft 2 swings about the first bearing 4 is referred to as a swing direction (D1). Details of the first bearing 4 will be described later.
  • the second bearing 11 is a deep groove ball bearing in which a ball (ball) as a rolling element is interposed between an annular outer ring and an inner ring.
  • the second bearing 11 is housed at the bottom of the gear case 3.
  • a step 2c formed near the tip of the worm shaft 2 is locked to the inner ring of the second bearing 11.
  • An end surface 17 a is formed on the outer peripheral surface of the gear case 3 so as to protrude from a flat flange portion 17.
  • a through hole 13 is formed in the flange portion 17 and opens toward the outer peripheral surface of the second bearing 11. The opening of the through hole 13 that opens to the end face 17 a of the flange 17 is closed by the plug 14.
  • the coil spring 12 is housed in a state where the coil spring 12 is compressed between the distal end surface of the plug 14 and the outer peripheral surface of the second bearing 11 in the through hole 13.
  • the coil spring 12 urges the second bearing 11 in a direction in which a gap between the teeth 2e of the worm 2a and the teeth 1a of the worm wheel 1 is reduced, that is, in a direction in which the worm 2a meshes with the worm wheel 1.
  • the inner peripheral surface 3b surrounding the outer peripheral surface of the second bearing 11 in the gear case 3 has a pair of parallel flat portions so that the second bearing 11 can move toward the worm wheel 1 by the urging force of the coil spring 12. It is formed in a long hole shape.
  • the inner peripheral surface 3b may have any shape as long as the second bearing 11 can move inside the inner peripheral surface 3b.
  • the inner peripheral surface 3b may have a round hole shape whose inner diameter is larger than the outer diameter of the second bearing 11, and there is no need to form a pair of parallel flat portions.
  • the second bearing 11 is urged toward the worm wheel 1 by the urging force of the coil spring 12, and the backlash between the worm 2a and the worm wheel 1 is increased. There is no (gap). In this state, the worm shaft 2 is tilted about the first bearing 4 as a fulcrum by the urging force of the coil spring 12.
  • the first bearing 4 is provided with an internal gap 144 so that the inner ring 142 fixed to the worm shaft 2 can swing with respect to the outer ring 141 fixed to the gear case 3.
  • the internal clearance 144 is provided over the entire circumference of the first bearing 4, when a force in the axial direction (D3) acts on the worm shaft 2, the inner ring 142 together with the worm shaft 2 slightly moves in the axial direction (D3). May move. Therefore, for example, when a force in the axial direction (D3) acts on the worm shaft 2 from the electric motor 7 at the time of reverse steering, the ball 143 collides with the outer ring 141 or the inner ring 142, and noise (collision sound) is generated. There is a risk. Also, when a force in the axial direction (D3) acts on the worm shaft 2 from the worm wheel 1 via the wheels 6, the rack shaft 8, the output shaft 22, and the like from the road surface, noise (collision noise) may similarly be generated. There is also.
  • the inside of the first bearing 4 is set.
  • the size of the gap 144 is made different depending on the position in the circumferential direction.
  • an internal gap 144 having a predetermined length X (> 0) is secured, and each is orthogonal to the swing direction (D1) and the axial direction (D3) of the worm shaft 2.
  • the orthogonal direction (D2) which is the second direction, the internal gap 144 is set to 0 or almost 0.
  • FIG. 4 is a perspective view of the speed reducer 100 with the gear case 3 partially cut away. 4, illustration of the worm wheel 1 is omitted.
  • FIG. 5 is a schematic cross-sectional view of the speed reducer 100 along the line VV in FIG.
  • the shaft support structure 101 of the speed reducer 100 further includes a bolt 150 as a pressing portion that presses the outer periphery of the outer ring 141 of the first bearing 4 in the orthogonal direction (D2).
  • the gear case 3 has an insertion hole 133 through which the bolt 150 is inserted.
  • the insertion hole 133 is a through hole that penetrates in the orthogonal direction (D2), and a female screw that is screwed to a male screw formed on the outer periphery of the shaft of the bolt 150 is formed on the inner peripheral surface. Therefore, by rotating the bolt 150 from outside the gear case 3 using a tool or the like, the bolt 150 can be moved in the orthogonal direction (D2) along the insertion hole 133.
  • the bottom 131 that faces the insertion hole 133 is a support that supports the first bearing 4. That is, the housing hole 130 of the gear case 3 forms a part of the shaft support structure 101, and the bottom 131 of the housing hole 130 functions as a pressing portion that presses the outer circumference of the outer ring 141 of the first bearing 4 in the orthogonal direction (D2). .
  • the outer ring 141 of the first bearing 4 is sandwiched in the orthogonal direction (D2) between the bolt 150 as a pressing portion and the bottom 131 as a pressing portion formed in the housing hole 130.
  • the outer ring 141 of the first bearing 4 has a circular outer and inner circumference before being assembled to the gear case 3.
  • the outer ring 141 of the first bearing 4 is compressed in the orthogonal direction (D2) and expands in the swing direction (D1). Deform to.
  • the outer ring 141 of the first bearing 4 is assembled to the gear case 3 and, after the bolt 150 is screwed by a predetermined amount, the outer circumference and the inner circumference each have an elliptical shape. Become.
  • the bolt 150 is arranged such that the central axis of the worm shaft 2 is located on an extension of the central axis. For this reason, the bolt 150 presses the outer peripheral surface of the outer ring 141 toward the central axis of the worm shaft 2.
  • the tip surface 151 of the shaft of the bolt 150 is formed so as not to prevent the outer ring 141 from being deformed into an elliptical shape when the outer ring 141 is pressed by the bolt 150.
  • the tip surface 151 of the shaft of the bolt 150 is formed in a flat shape.
  • the inner peripheral surface of the housing hole 130 is formed so as not to hinder the outer ring 141 from being deformed into an elliptical shape when the outer ring 141 is pressed by the bolt 150.
  • the radius of curvature of the inner peripheral surface of the bottom portion 131 of the housing hole 130 is formed to be larger than the radius of curvature of a portion of the outer ring 141 deformed into an elliptical shape that comes into contact with the bottom portion 131.
  • the outer ring 141 deformed into an elliptical shape may have both ends in the swing direction (D1) in contact with the inner peripheral surface of the housing hole 130, or may not be in contact as illustrated.
  • At least the first bearing 4 is set so that the pressing force acting on the first bearing 4 in the orthogonal direction (D2) is greater than the pressing force acting on the first bearing 4 in the swing direction (D1).
  • the outer ring 141 may be configured to be pressed.
  • the diameter of the shaft portion of the bolt 150 is set to, for example, ⁇ or more of the width (length in the axial direction (D3)) of the outer ring 141 in order to secure a pressing range against the outer peripheral surface of the outer ring 141.
  • the diameter of the bolt 150 may be set to be smaller than the width of the outer ring 141. preferable. Further, by setting the diameter of the bolt 150 to be smaller than the width of the outer ring 141, the degree of freedom in layout is also improved.
  • FIG. 6 is a schematic cross-sectional view of the inner ring 142 and the outer ring 141 of the first bearing 4 along the line VI-VI in FIGS. 7 and 8. 6, illustration of the ball 143 is omitted.
  • FIG. 7 is a schematic sectional view of the first bearing 4 along the line VII-VII in FIG. 6, and FIG. 8 is a schematic sectional view of the first bearing 4 along the line VIII-VIII in FIG. 6 to 8, illustration of a retainer that holds the ball 143 is omitted.
  • the inner diameter of the inner ring 142 of the first bearing 4 is shown smaller than those shown in FIGS. In FIG. 7, the internal gap 144 is exaggerated and enlarged.
  • the first bearing 4 is disposed between the inner race 142 having the inner race groove 142a, the outer race 141 having the outer race groove 141a, and the inner race groove 142a and the outer race groove 141a.
  • the outer ring 141 is pressed in the orthogonal direction (D2) by the bolt 150 and is held in the accommodation hole 130 in a state of being deformed into an elliptical shape.
  • the outer raceway groove 141a that forms the inner peripheral surface of the outer ring 141 has a major axis length of 2 ⁇ La and a minor axis length of 2 ⁇ L in a cross section orthogonal to the axial direction (D3) of the worm shaft 2. It has an elliptical shape of Lb (La> Lb).
  • the inner raceway groove 142a which is the outer peripheral surface of the inner ring 142, has a circular shape with a diameter Do.
  • the distance L2 between the inner raceway groove 142a and the outer raceway groove 141a becomes larger than before the deformation. Therefore, the internal gap 144 in the swing direction (D1) can be made larger than before the deformation.
  • the length X of the internal gap 144 in the swing direction (D1) allows the worm shaft 2 to swing in the swing direction (D1), and effectively causes the backlash between the worm 2a and the worm wheel 1.
  • (Gap) is set to a length that can be reduced.
  • the distance L1 is set to be equal to or slightly longer than the outer diameter of the ball 143 so that the length of the internal gap 144 in the orthogonal direction (D2) is zero or almost zero. Since the distance L1 and the distance L2 are set as described above, the length of the internal gap 144 in the orthogonal direction (D2) is smaller than the length X of the internal gap 144 in the swing direction (D1).
  • the bolt 150 is provided movably in the orthogonal direction (D2) in the insertion hole 133. Further, the first bearing 4 is configured such that the distance L1 between the inner raceway groove 142a and the outer raceway groove 141a in the orthogonal direction (D2) can be adjusted according to the screwing amount of the bolt 150. Therefore, the internal clearance 144 of the first bearing 4 in the orthogonal direction (D2) can be easily adjusted by the screwing amount of the bolt 150.
  • the length of the internal clearance 144 of the first bearing 4 in the orthogonal direction (D2) is determined by the distance from the receiving seat of the bolt 150 formed in the gear case 3 to the top surface of the head of the bolt 150 or the worm shaft 2 Can be managed by measuring the amount of rocking when a predetermined load is applied to the. As shown in FIG. 5, a shim 156 having a predetermined thickness may be interposed between the head of the bolt 150 and a receiving seat formed on the gear case 3 so as to obtain a predetermined swing amount. Good.
  • the outer raceway groove 141a of the first bearing 4 assembled to the power steering device 10 according to the present embodiment is orthogonal to the swing direction (D1) and the axial direction (D3) of the worm shaft 2 (D3).
  • the ellipse is formed so that the distance L1 between the inner raceway groove 142a and the outer raceway groove 141a in D2) is smaller than the distance L2 between the inner raceway groove 142a and the outer raceway groove 141a in the swing direction (D1). It is shaped. For this reason, while securing the internal clearance 144 of the first bearing 4 in the swing direction (D1), the internal clearance 144 of the first bearing 4 in the orthogonal direction (D2) is larger than the internal clearance 144 in the swing direction (D1). Can be smaller.
  • the outer race 141 of the first bearing 4 is held in a state of being pressed in the orthogonal direction (D2) by the bolts 150 and the bottom 131 of the receiving hole 130, so that the inner raceway groove 142a in the orthogonal direction (D2)
  • the distance L1 between the outer raceway groove 141a and the outer raceway groove 141a is deformed to be smaller than the distance L2 between the inner raceway groove 142a and the outer raceway groove 141a in the swing direction (D1).
  • the outer ring 141 is pressed by the bolt 150 and deformed into an elliptical shape, so that the internal clearance 144 of the first bearing 4 in the orthogonal direction (D2) can be easily reduced.
  • the manufacturing cost of the first bearing 4 can be reduced. Further, since a standard deep groove ball bearing can be used as the first bearing 4, the first bearing 4 can be easily obtained. Therefore, the cost of the power steering device 10 can be reduced.
  • the speed reducer 200 includes an annular pressing ring 250 as a pressing portion instead of the bolt 150 described in the first embodiment.
  • the gear case 203 of the speed reducer 200 is formed with a housing hole 230 for housing the first bearing 4.
  • the outer ring 141 of the first bearing 4 is held in the axial direction (D3) between the stepped portion 3a formed in the gear case 203 and the lock nut 5 fastened in the gear case 203.
  • the inner race 142 is sandwiched in the axial direction (D3) between the stepped portion 2b of the worm shaft 2 and the worm-side joint 9 (see FIG. 2) of the shaft coupler 19 which is press-fitted into the end of the worm shaft 2.
  • the housing hole 230 has a small diameter portion 230a having an inner diameter slightly larger than the outer diameter of the outer ring 141 of the first bearing 4, and a large diameter portion 230b having an inner diameter larger than the small diameter portion 230a.
  • the pressing ring 250 is loosely fitted to the large diameter portion 230b.
  • the pressing ring 250 is an annular member into which the outer ring 141 of the first bearing 4 is press-fitted.
  • the pressing ring 250 is provided with low rigidity portions 251 having lower rigidity than both ends 250b in the orthogonal direction (D2) at both ends 250a in the swinging direction (D1).
  • the low-rigidity portion 251 is formed such that the width in the radial direction is smaller than the width in the radial direction in another portion (for example, both ends 250b in the orthogonal direction (D2)). That is, the low-rigidity portion 251 is a thin portion whose thickness (radial width) is smaller than the thickness (radial width) of both ends 250b in the orthogonal direction (D2).
  • the low-rigidity portion 251 may be any portion that has lower rigidity than other portions. For this reason, even if it has the same thickness (radial width) as the other portions, the low-rigidity portion may be formed by providing a plurality of grooves or through holes.
  • the pressing ring may be formed by joining both ends of a pair of semi-arc members with members having a lower elastic modulus than the semi-arc members.
  • the connecting member that connects the semicircular arc-shaped members serves as a low rigidity portion.
  • the low-rigidity portion 251 can adopt various forms.
  • the low-rigidity portion 251 when the low-rigidity portion 251 is a thin portion having a smaller thickness than other portions, the low-rigidity portion 251 has a low rigidity. Since the rigid portion 251 can be easily formed, the manufacturing cost of the speed reducer 200 can be reduced.
  • the low-rigidity portion 251 is formed by forming a pair of flat rectangular surfaces on the outer periphery of the annular ring member.
  • the outer flat surfaces of the pair of low rigidity portions 251 are formed parallel to each other.
  • the interval (two-plane width) in the swing direction (D1) between the outer flat surfaces of the pair of low-rigidity portions 251 is smaller than the outer diameter of the pressing ring 250.
  • the inner diameter of the pressing ring 250 is slightly smaller than the outer diameter of the outer ring 141 of the first bearing 4.
  • the pressing ring 250 is provided with a pair of low-rigid portions 251, when the outer ring 141 of the first bearing 4 is press-fitted into the inner circumference of the pressing ring 250, as shown by a solid line in FIG.
  • the pressing ring 250 is deformed so that the shape becomes elliptical. This is because the low rigidity portion 251 has lower rigidity than other portions (for example, both ends 250b in the orthogonal direction) and is easily deformed.
  • both ends of the outer ring 141 of the first bearing 4 in the orthogonal direction (D2) are provided at both ends in the swing direction (D1) of the outer ring 141 of the first bearing 4.
  • a pressing force greater than the pressing force applied to both ends acts.
  • the pressing ring 250 acts on the first bearing 4 so that the pressing force in the orthogonal direction (D2) against the first bearing 4 is larger than the pressing force in the swing direction (D1) on the first bearing 4.
  • the outer ring 141 is pressed. Therefore, as the inner circumference of the pressing ring 250 is deformed into an elliptical shape, the outer ring 141 of the first bearing 4 is also deformed into an elliptical shape.
  • the pressing ring 250 before deformation is indicated by a two-dot chain line.
  • the distance between both ends 250a in the swinging direction (D1) of the pressing ring 250 after the deformation is larger than before the deformation. That is, the press ring 250 extends in the swing direction (D1) when the outer ring 141 is press-fitted.
  • the distance between both ends 250b of the pressing ring 250 in the orthogonal direction (D2) after the deformation is smaller than before. That is, the press ring 250 is compressed in the orthogonal direction (D2) by press-fitting the outer ring 141.
  • the axial width W1 of the pressing ring 250 is smaller than the axial width W2 of the outer ring 141 (W1 ⁇ W2).
  • the position of the pressing ring 250 is defined by being clamped between a step formed between the small diameter portion 230a and the large diameter portion 230b and the lock nut 5.
  • One end of the first bearing 4 protrudes from the pressing ring 250 in the axial direction (D3), and the protruding portion 4a of the first bearing 4 is fitted into the small-diameter portion 230a of the accommodation hole 230.
  • the fit between the projecting portion 4a of the first bearing 4 and the small-diameter portion 230a of the housing hole 230 is "clearance fit".
  • the inner circumference of the pressing ring 250 is not in contact with the protrusion 4a. That is, the protruding portion 4 a is a portion that does not receive the pressing force directly from the pressing ring 250. Thereby, the deformation of the protruding portion 4a due to the pressing force of the pressing ring 250 is suppressed, so that the protruding portion 4a can be fitted into the small-diameter portion 230a of the accommodation hole 230 by “clear fit”.
  • the outer ring 141 of the first bearing 4 can be compressed in the orthogonal direction (D2). Therefore, similarly to the first embodiment, the distance L1 between the inner raceway groove 142a and the outer raceway groove 141a in the orthogonal direction (D2) is equal to the distance L1 between the inner raceway groove 142a and the outer raceway groove 141a in the swing direction (D1).
  • the first bearing 4 can be deformed so as to be smaller than the distance L2 between the two (see FIGS. 6 to 8). Therefore, according to the second embodiment, the same operation and effect as those of the first embodiment can be obtained.
  • the compression amount of the first bearing 4 in the orthogonal direction (D2) can be set by the rigidity of the low rigidity portion 251.
  • the internal clearance 144 of the first bearing 4 in the orthogonal direction (D2) can be appropriately set.
  • ⁇ Modification 2> In the first embodiment, the example in which the bolt 150 functions as a pressing portion that presses the outer ring 141 has been described, but the present invention is not limited to this.
  • a pair of upper and lower through holes facing the housing hole 130 may be formed, and the outer ring 141 may be sandwiched from above and below by a clamp having a pair of pressing portions inserted into the through hole.
  • the outer ring 141 is deformed into an elliptical shape by applying a pressing force to each of the upper and lower portions of the outer peripheral surface of the outer ring 141 by a clamp or the like.
  • a pressing portion may be formed in the receiving hole 330 that receives the first bearing 4.
  • the housing hole 330 is formed between a pair of fitting surfaces 350 on both ends of the outer ring 141 of the first bearing 4 in the orthogonal direction (D2) by press-fitting, and the outer ring 141 of the first bearing 4.
  • a concave portion 353 that is disposed to face both ends in the first direction and that is depressed radially outward from the fitting surface 350.
  • the pair of fitting surfaces 350 are arc-shaped surfaces, and the inner diameter thereof is slightly smaller than the outer diameter of the outer ring 141 of the first bearing 4. Therefore, when the outer ring 141 of the first bearing 4 is press-fitted into the accommodation hole 330, the outer periphery of the outer ring 141 is pressed by the pair of fitting surfaces 350. That is, in the present modification, the pair of fitting surfaces 350 function as a pressing portion that presses the outer periphery of the outer ring 141 of the first bearing 4.
  • the depth of the recess 353 is set to a sufficient depth so as not to prevent the outer ring 141 of the first bearing 4 from being deformed into an elliptical shape. In this modification, the bottom surface of the recess 353 does not contact the outer ring 141. That is, no pressing force acts on the outer periphery of the outer ring 141 facing the recess 353.
  • the pair of fitting surfaces 350 is such that the pressing force in the orthogonal direction (D2) against the first bearing 4 is the pressing force in the swing direction (D1) against the first bearing 4 (in this modification, the first direction).
  • the outer ring 141 of the first bearing 4 is pressed so that the pressing force of (D1) is larger than 0 (zero).
  • the internal gap 144 of the first bearing 4 is secured in the orthogonal direction (D2) while the internal gap 144 of the first bearing 4 is secured in the swing direction (D1). It can be smaller than the internal gap 144 in the swing direction (D1).
  • This allows the inner ring 142 to move in the axial direction together with the worm shaft 2 when an axial force acts on the worm shaft 2 while allowing the worm shaft 2 to swing.
  • it is possible to reduce the collision noise caused by the ball 143 colliding with the outer ring 141 or the inner ring 142, and reduce the noise of the speed reducer.
  • the fitting surface 350 since the fitting surface 350 has a simple configuration in which the concave portion 353 is provided, it is possible to reduce the manufacturing cost of the speed reducer.
  • the outer periphery of the outer ring 141 and the outer raceway groove 141a may be deformed into an elliptical shape by forming the accommodation hole 130 into an elliptical shape and press-fitting the circular outer ring 141 into the accommodation hole 130. Further, by forming the accommodation hole 130 in a circular shape and pressing the elliptical outer ring 141 into the accommodation hole 130, the outer periphery of the outer ring 141 is deformed into a circular shape, and the outer raceway groove 141a of the outer ring 141 is formed into an elliptical shape. It may be deformed.
  • the contact portion of the housing hole 130 with the outer ring 141 functions as a pressing portion that deforms the outer ring 141.
  • pressing members such as the bolt 150 and the pressing ring 250 can be omitted. That is, when the pressing portion is formed in the receiving hole 330, the pressing portion formed in the receiving hole 330 presses the outer ring 141 of the first bearing 4 in the second direction (D2). The number of parts can be reduced as compared with the case of providing.
  • the present invention is not limited to this.
  • the outer race 141 having the elliptical outer raceway groove 141a may be fixed to the housing hole 130 in advance.
  • the outer raceway groove 141a can be made elliptical by removing the pressing force.
  • the elliptical outer raceway groove 141a is formed in the first bearing 4 in advance, so that the bolt 150 can be omitted.
  • the outer shape can be any shape.
  • the outer shape of the outer ring 141 can be circular.
  • the outer raceway groove 141a may be formed as a continuous curved surface. At least, the distance L1 between the inner raceway groove 142a and the outer raceway groove 141a in the orthogonal direction (D2) is smaller than the distance L2 between the inner raceway groove 142a and the outer raceway groove 141a in the swing direction (D1). I just need to be.
  • the first bearing 4 may be at least a ball bearing, and may be a self-aligning ball bearing or an angular ball bearing.
  • ⁇ Modification 8> In the above embodiment, an example was described in which the worm gear having the worm 2a as the drive gear and the worm wheel 1 as the driven gear was used as the speed reducer 100, but the present invention is not limited to this.
  • a hypoid gear having a hypoid pinion as a driving gear and a hypoid wheel as a driven gear may be used as a reduction gear. Further, a bevel gear may be used as a speed reducer.
  • the reduction gears 100 and 200 each include a drive gear shaft (worm shaft 2) connected to a drive source (electric motor 7) and a driven gear (worm wheel 1) that meshes with the drive gear shaft (worm shaft 2).
  • a first bearing 4 rotatably supporting a base end side of a drive gear shaft (worm shaft 2) and a second bearing 11 rotatably supporting a distal end side of the drive gear shaft (worm shaft 2).
  • a biasing member for biasing the drive gear shaft (worm shaft 2) toward the driven gear (worm wheel 1) via the second bearing 11;
  • An inner race 142 having an inner race groove 142a, an outer race 141 having an outer race groove 141a, and a plurality of rolling elements (balls 143) arranged between the inner race groove 142a and the outer race groove 141a.
  • Drive gear shaft W The inner raceway groove 142a and the outer raceway in a second direction (D2) orthogonal to the first direction (D1) in which the shaft 2) swings and the axial direction (D3) of the drive gear shaft (worm shaft 2).
  • the distance L1 between the raceway groove 141a and the distance L2 between the inner raceway groove 142a and the outer raceway groove 141a in the first direction (D1) is smaller.
  • the internal clearance 144 of the first bearing 4 is secured in the second direction (D2) while the internal clearance 144 of the first bearing 4 is secured in the first direction (D1).
  • the inner ring 142 is formed together with the drive gear shaft (worm shaft 2). Movement in the axial direction can be suppressed.
  • the reduction gears 100 and 200 further include a pressing portion (a bottom portion 131, a bolt 150, a pressing ring 250, and a fitting surface 350) that presses the outer ring 141 of the first bearing 4 in the second direction (D2).
  • the outer race 141 is held in a state where it is pressed by the pressing portions (the bottom 131, the bolt 150, the pressing ring 250, the fitting surface 350), so that the inner raceway groove 142a and the outer raceway groove in the second direction (D2).
  • the distance L1 between the outer raceway 141a and the inner raceway groove 142a is smaller than the distance L2 between the inner raceway groove 142a and the outer raceway groove 141a in the first direction (D1).
  • the inner space 144 of the first bearing 4 in the second direction (D2) can be easily reduced by deforming the outer ring 141 by the pressing portion (the bottom 131, the bolt 150, the pressing ring 250, the fitting surface 350). can do.
  • the reduction gears 100 and 200 each include a drive gear shaft (worm shaft 2) connected to a drive source (electric motor 7) and a driven gear (worm wheel 1) that meshes with the drive gear shaft (worm shaft 2).
  • a first bearing 4 rotatably supporting a base end side of a drive gear shaft (worm shaft 2) and a second bearing 11 rotatably supporting a distal end side of the drive gear shaft (worm shaft 2).
  • an urging member coil spring 12 for urging the drive gear shaft (worm shaft 2) toward the driven gear (worm wheel 1) via the second bearing 11, and presses the outer periphery of the first bearing 4.
  • the first bearing 4 includes an inner race 142 having an inner raceway groove 142a and an outer racer 141 having an outer raceway groove 141a, and a pressing portion (bottom 131, bolt 150, pressing ring 250, fitting surface 350).
  • Inner track groove 142 And a plurality of rolling elements (balls 143) disposed between the outer raceway groove 141a and the outer raceway groove 141a.
  • the pressing portion (the bottom portion 131, the bolt 150, the pressing ring 250, and the fitting surface 350) includes a driving gear shaft ( The direction in which the worm shaft 2) swings is defined as a first direction (D1), and the direction orthogonal to each of the first direction (D1) and the axial direction (D3) of the drive gear shaft (worm shaft 2) is defined as a second direction (D1). D2), the outer ring 141 of the first bearing 4 such that the pressing force on the first bearing 4 in the second direction (D2) is greater than the pressing force on the first bearing 4 in the first direction (D1). Press.
  • the internal clearance 144 of the first bearing 4 is secured in the second direction (D2) while the internal clearance 144 of the first bearing 4 is secured in the first direction (D1).
  • the inner ring 142 is formed together with the drive gear shaft (worm shaft 2). Movement in the axial direction can be suppressed.
  • the pressing portion is a bolt 150 that is movable in the second direction (D2), and the first bearing 4 is configured such that the first bearing 4 moves the inner raceway groove 142a in the second direction (D2) in accordance with the screwing amount of the bolt 150.
  • the distance L1 between the outer raceway groove 141a and the outer raceway groove 141a is configured to be adjustable.
  • the internal clearance 144 of the first bearing 4 in the second direction (D2) can be easily adjusted by the screwing amount of the bolt 150.
  • the pressing portion is an annular member (pressing ring 250) into which the outer ring 141 of the first bearing 4 is press-fitted, and is provided at both ends 250 a in the first direction (D 1) in the second direction (D 2).
  • a low-rigidity portion 251 having lower rigidity than both ends 250b is provided.
  • the outer ring 141 of the first bearing 4 can be compressed in the second direction (D2) by press-fitting the first bearing 4 into the annular pressing portion (the pressing ring 250). It can be set by the rigidity of the low rigidity portion 251.
  • the low-rigidity portion 251 is a thin portion that is thinner than the thickness of both ends 250b in the second direction (D2).
  • the reduction gears 100 and 200 further include a case (gear case 3, 203) for accommodating the drive gear shaft (worm shaft 2), and the case (gear case 3, 203) has an accommodation hole 130, for accommodating the first bearing 4. 330 is formed, and the pressing portion (the bottom portion 131, the fitting surface 350) is formed in the receiving holes 130 and 330.
  • the outer ring 141 of the first bearing 4 is pressed in the second direction (D2) by the pressing portions (the bottom portion 131, the fitting surface 350) formed in the receiving holes 130 and 330.
  • the number of parts can be reduced as compared with the case where a pressing portion is provided separately from 203).
  • the housing hole 330 has a pair of fitting surfaces 350 into which both ends of the outer ring 141 of the first bearing 4 in the second direction (D2) are press-fitted, and the outer ring 141 of the first bearing 4. And a recess 353 which is disposed opposite to both ends in the first direction (D1) and is depressed radially outward from the fitting surface 350.
  • the pair of fitting surfaces 350 presses the outer ring 141. Department.
  • the power steering device 10 includes the speed reducer 100 and an electric motor 7 as a drive source.
  • a driven gear (worm wheel 1) applies a torque of the electric motor 7 to a rack shaft 8 that steers the wheels 6.
  • the reduction gear 100 is provided on the output shaft 22 for transmission, and reduces the rotation of the drive gear shaft (worm shaft 2) and transmits the rotation to the driven gear (worm wheel 1).

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Power Steering Mechanism (AREA)

Abstract

L'invention concerne un réducteur (100) étant pourvu : d'un premier palier (4) qui supporte un côté d'extrémité de base d'un arbre de transmission ; un second palier qui supporte le côté d'extrémité avant de l'arbre de transmission ; et un élément de sollicitation qui sollicite l'arbre de transmission vers un engrenage entraîné. Le premier palier (4) a une bague intérieure (142) ayant une rainure de course intérieure (142a) et une bague extérieure (141) ayant une rainure de course extérieure (141a), la distance (L1) entre la rainure de course intérieure (142a) et la rainure de course extérieure (141a) dans une deuxième direction (D2) perpendiculaire à chacune d'une première direction (D1), dans laquelle l'arbre de transmission oscille, et la direction axiale (D3) de l'arbre de transmission est inférieure à la distance (L2) entre la rainure de course intérieure (142a) et la rainure de course extérieure (141a) dans la première direction (D1).
PCT/JP2019/023278 2018-06-28 2019-06-12 Réducteur et dispositif de direction assistée WO2020004037A1 (fr)

Applications Claiming Priority (2)

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JP2018123047 2018-06-28
JP2018-123047 2018-06-28

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WO2020004037A1 true WO2020004037A1 (fr) 2020-01-02

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100140011A1 (en) * 2006-11-04 2010-06-10 Mark Anthony Wilkes Worm gear for electric assisted steering apparatus and method controlling the movement of the worm shaft in a worm gearing

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100140011A1 (en) * 2006-11-04 2010-06-10 Mark Anthony Wilkes Worm gear for electric assisted steering apparatus and method controlling the movement of the worm shaft in a worm gearing

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