WO2005001309A1 - ウォーム減速機及び電動式パワーステアリング装置 - Google Patents
ウォーム減速機及び電動式パワーステアリング装置 Download PDFInfo
- Publication number
- WO2005001309A1 WO2005001309A1 PCT/JP2004/008887 JP2004008887W WO2005001309A1 WO 2005001309 A1 WO2005001309 A1 WO 2005001309A1 JP 2004008887 W JP2004008887 W JP 2004008887W WO 2005001309 A1 WO2005001309 A1 WO 2005001309A1
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- WIPO (PCT)
- Prior art keywords
- worm
- shaft
- worm shaft
- bearing
- gear housing
- Prior art date
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Classifications
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- 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
-
- 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
- B62D5/0409—Electric motor acting on the steering column
-
- 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
- F16C25/083—Ball or roller bearings self-adjusting with resilient means acting axially on a race ring to preload the bearing
-
- 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
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
- H02K7/08—Structural association with bearings
- H02K7/081—Structural association with bearings specially adapted for worm gear drives
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
- H02K7/10—Structural association with clutches, brakes, gears, pulleys or mechanical starters
- H02K7/116—Structural association with clutches, brakes, gears, pulleys or mechanical starters with gears
- H02K7/1163—Structural association with clutches, brakes, gears, pulleys or mechanical starters with gears where at least two gears have non-parallel axes without having orbital motion
- H02K7/1166—Structural association with clutches, brakes, gears, pulleys or mechanical starters with gears where at least two gears have non-parallel axes without having orbital motion 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
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C2361/00—Apparatus or articles in engineering in general
- F16C2361/61—Toothed gear systems, e.g. support of pinion shafts
-
- 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
- F16C2380/00—Electrical apparatus
- F16C2380/26—Dynamo-electric machines or combinations therewith, e.g. electro-motors and generators
- F16C2380/27—Motor coupled with a gear, e.g. worm gears
-
- 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
- F16H2057/0213—Support of worm gear shafts
-
- 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
- F16H2057/0222—Lateral adjustment
-
- 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
- F16H55/22—Toothed members; Worms for transmissions with crossing shafts, especially worms, worm-gears
- F16H55/24—Special devices for taking up backlash
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T74/00—Machine element or mechanism
- Y10T74/19—Gearing
- Y10T74/19642—Directly cooperating gears
- Y10T74/19698—Spiral
- Y10T74/19828—Worm
Definitions
- the worm speed reducer and the electric power steering device according to the present invention are incorporated into, for example, a steering device of a vehicle, and a driver operates a steering wheel by using an output of an electric motor as auxiliary power. Use to reduce the power required for
- the worm reduction gear according to the present invention is used by being incorporated in a linear actuator incorporated in various mechanical devices such as an electric bed, an electric table, an electric chair, and a lifter, in addition to the electric power steering device.
- Power steering is a device for reducing the force required for a driver to operate a steering wheel when giving a steering angle to a steered wheel (except for a special vehicle such as a forklift or the like, which is usually a front wheel).
- the device is widely used.
- an electric power steering apparatus using an electric motor as an auxiliary power source has begun to be widely used in recent years.
- Electric power steering devices are smaller and lighter than hydraulic power steering devices. They have the advantages of being able to control the amount of auxiliary power (torque) easily, and reducing power and engine power loss. is there.
- FIG. 46 schematically shows a basic configuration of such an electric power steering apparatus which has been known in the related art.
- a tonnole sensor 3 for detecting the direction and magnitude of the torque applied to the steering shaft 2 from the steering wheel 1, and a reduction gear 4 are provided.
- the output side of the speed reducer 4 is connected to an intermediate portion of the steering shaft 2, and the input side is connected to the rotation shaft of the electric motor 5.
- the detection signal of the torque sensor 3 is input to a controller 6 for controlling the energization of the electric motor 5 together with a signal indicating the vehicle speed.
- a worm reducer having a large lead angle and having reversibility with respect to the power transmission direction is generally used as the reducer 4.
- the home wheel which is a torque receiving member, is fixed to the intermediate portion of the steering shaft 2 and the torque is applied.
- a worm of a worm shaft which is a member and is fixedly connected to the rotation shaft of the electric motor 5, is combined with the worm wheel.
- the torque sensor 3 detects the rotation direction and the torque of the steering shaft 2. , And sends a signal representing the detected value to the controller 6. Then, the controller 6 energizes the electric motor 5 to rotate the steering shaft 2 via the speed reducer 4 in the same direction as the rotation direction based on the steering wheel 1. As a result, the tip end (the lower end in FIG. 46) of the steering shaft 2 rotates with a torque larger than the torque based on the force applied from the steering wheel 1.
- Such rotation of the distal end of the steering shaft 2 is transmitted to the input shaft 10 of the steering gear 9 via the universal joint 7 and the intermediate shaft 8.
- the input shaft 10 rotates a pinion 11 constituting the steering gear 9, pushes and pulls a tie rod 13 through a rack 12, and gives a desired steering angle to the steered wheels 14.
- the torque transmitted from the distal end of the steering shaft 2 to the intermediate shaft 8 via the universal joint 7 is transmitted from the steering wheel 1 to the base end of the steering shaft 2 (FIG. 46).
- the upper end of the motor is greater by the auxiliary power applied from the electric motor 5 via the speed reducer 4. Therefore, the force required for the driver to operate the steering wheel 1 to give the steering angle to the steered wheels 14 can be reduced by the amount of the auxiliary power.
- a worm speed reducer is used as the speed reducer 4 provided between the electric motor 5 and the steering shaft 2.
- this worm reducer has unavoidable backlash.
- the backlash increases as the dimensional error and the mounting error of the worm shaft, the worm wheel, and the bearings for supporting these members, which are the components of the worm speed reducer, increase. If there is a large backlash, the tooth surfaces of the worm wheel and the worm strongly collide with each other, which may cause unpleasant rattle.
- Patent Document 1-4 As prior art documents related to the present invention, there is Patent Document 1-4.
- Patent Document 1 JP-A-2000-43739
- Patent Document 2 Japanese Patent Application Laid-Open No. 2002-37094
- Patent Document 3 Japanese Patent Application Laid-Open No. 2001-322554
- Patent Document 4 JP-A-2002-67992
- the present invention has been devised in order to suppress generation of unpleasant rattle at a joint between a worm wheel and a worm shaft with an inexpensive structure.
- a worm speed reducer includes a worm wheel, a worm shaft, and an elastic body, and the elastic body imparts a directional force to the worm wheel to the worm shaft. It is.
- the elastic body provides the worm shaft with elasticity in the direction toward the worm wheel. For this reason, the worm wheel and worm shaft It is possible to apply a preload to the joint, and it is possible to suppress the generation of unpleasant rattle at the joint.
- FIG. 1 is a diagram showing a first embodiment of the present invention with a part thereof cut away.
- FIG. 2 is a cross-sectional view taken along line AA of FIG.
- FIG. 3 is an enlarged cross-sectional view of the left half of FIG. 2.
- FIG. 4 is an enlarged sectional view of the right half.
- FIG. 5 is an enlarged cross-sectional view of the right half of FIG.
- FIG. 6 is a sectional view taken along line BB of FIG. 5.
- FIG. 7 is a view showing a combination of a preload pad and a worm shaft taken out and viewed from the tip side of the worm shaft.
- FIG. 8 is a perspective view showing a state in which a combination of a holder, a preload pad, and a torsion coil spring is taken out and viewed from the right in FIG. 5.
- FIG. 9 is an exploded perspective view of FIG.
- FIG. 10 is a view similar to FIG. 7, but showing Example 2 of the present invention.
- FIG. 11 is a view showing a preload pad used in Example 3.
- FIG. 12 is a perspective view showing a state where a holder, a preload pad, and a torsion coil spring are similarly separated.
- FIG. 13 is a view similar to FIG. 6, but showing Example 4 of the present invention.
- FIG. 14 is a view showing a combination of a holder, a preload pad, and a torsion coil spring used in the fourth embodiment.
- FIG. 15 is a diagram showing an example of a structure in which an electric motor and a worm speed reducer are provided around a pinion.
- FIG. 16 is a diagram showing an example of a structure in which an electric motor and a worm speed reducer are provided around a sub-pinion.
- FIG. 17 is a view similar to FIG. 3, showing one example of an electric motor having a brushless structure.
- FIG. 18 is a diagram showing a fifth embodiment of the present invention, with a part cut away.
- FIG. 19 is a partial cross-sectional view of a CC portion in FIG. FIG. 20]
- FIG. 20 is a sectional view taken along the line DD of FIG.
- FIG. 21 is a cross-sectional view of the electric motor.
- FIG. 22 is a partially enlarged view of FIG.
- FIG. 23 is a sectional view taken along a line E_E in FIG.
- FIG. 24 is a sectional view taken along the line FF of FIG.
- FIG. 25 is a view showing Example 6 of the present invention, similar to FIG. 23.
- FIG. 26 is a sectional view taken along line GG of FIG.
- FIG. 27 is a view showing Example 7 of the present invention, similar to FIG. 25.
- FIG. 28 is a view similar to FIG. 22, illustrating Example 8 of the present invention.
- FIG. 29 is a sectional view taken along line HH of FIG.
- FIG. 30 is an enlarged cross-sectional view showing Example 9 of the present invention and corresponding to the portion I in FIG. 19.
- FIG. 31] FIG. 31 is a view similar to FIG. is there.
- FIG. 32 is an enlarged cross-sectional view showing Example 11 and corresponding to portion J in FIG. 31.
- FIG. 33] FIG. 33 is a view showing Example 12 similar to FIG. 32.
- FIG. 34 is a sectional view taken along the line K-K in FIG. 33, showing only the elastic ring.
- FIG. 35 is an enlarged cross-sectional view showing Example 13 of the present invention and corresponding to the L part in FIG. 31.
- FIG. 36 is a view similar to FIG. 35, illustrating Example 14;
- FIG. 37 is a cross-sectional view taken along the line MM of FIG. 36.
- FIG. 38 is a diagram showing an example of a structure in which an electric motor is provided around a pinion.
- FIG. 39 shows an example of a structure in which an electric motor is provided around a sub-pinion. It is a figure.
- FIG. 40 is a view showing Example 15 of the present invention and corresponding to an AA cross section in FIG. 1.
- FIG. 41 is an enlarged sectional view of a portion N in FIG. 40.
- FIG. 42 is a sectional view taken along a line __ in FIG.
- FIG. 43 is a cross-sectional view taken along the line PP of FIG. 41.
- FIG. 44 is a perspective view showing a state immediately before a bearing holder element, a fourth ball bearing, and a flexible ring are combined.
- FIG. 45 is a diagram showing (A) a Q-Q cross section of FIG. 42 and (b) a RR cross-section of FIG. 42, respectively.
- FIG. 46 is a schematic view showing the overall structure of an electric power steering device to which the present invention is applied.
- FIG. 47 is a schematic cross-sectional view for explaining the direction of a reaction force applied to the worm shaft from the worm wheel when the electric motor is driven to rotate in a predetermined direction.
- FIG. 3 is a sectional view taken along line S—S of FIG.
- FIG. 48 is a schematic cross-sectional view for explaining the direction of a reaction force applied from the worm wheel to the worm shaft when the electric motor is driven to rotate in the direction opposite to the above-mentioned predetermined direction.
- (A) is a cross-sectional view of (a) in FIG.
- FIG. 49 is a view similar to FIG. 47 (b), showing two-directional reaction forces applied to the worm shaft from the worm wheel when the electric motor is driven to rotate in both directions.
- FIG. 50 is a sectional view showing an example of a conventional structure of a worm speed reducer.
- FIG. 51 is a sectional view taken along the line U—U in FIG. 50.
- FIG. 52 is a schematic perspective view showing a component force of forces applied to these members when a driving force is transmitted between the worm shaft and the worm wheel.
- FIG. 53 is a schematic cross-sectional view for explaining a direction of a reaction force applied from the worm wheel to the worm shaft when the electric motor is driven to rotate in a predetermined direction.
- FIG. 54 is a schematic cross-sectional view for explaining a direction of a reaction force applied to the worm shaft from the worm wheel when the electric motor is driven to rotate in a direction opposite to the predetermined direction.
- FIG. 55 is a cross-sectional view showing another example of the conventional structure of the worm speed reducer.
- FIG. 56 is a sectional view taken along the line V_V in FIG. 55.
- a worm speed reducer includes a worm wheel, a worm shaft, and an elastic body, and the elastic body imparts a directional force to the worm wheel to the worm shaft. It is.
- the elastic body gives a worm shaft a directional force and a directional elastic force to a worm wheel via a preload pad.
- the worm wheel is freely fixed to the assist shaft.
- the above-mentioned worm shaft is supported inside the gear housing at a portion near both ends by a pair of bearings, and a worm provided at an intermediate portion is combined with the worm wheel.
- the preload pad is regulated by a guide surface provided on a gear housing or a member fixed to the gear housing to restrict displacement in a predetermined direction, and based on elasticity of the elastic body. Eliminate or reduce the gap with the guide surface by the elastic deformation of the preload pad itself
- the elastic body gives the worm shaft an elastic force in a direction toward the worm wheel via a preload pad.
- the worm wheel is freely fixed to the assist worm shaft.
- the preload pad is composed of a pair of elements, and a displacement in a predetermined direction is regulated by a guide surface provided on the gear housing or a member fixed to the gear housing. The gap with the guide surface is eliminated or reduced by displacing the pair of elements in a direction away from each other based on elasticity.
- Patent Document 1 describes a worm speed reducer that considers reducing backlash at a joint between a worm wheel and a worm shaft.
- This worm speed reducer is incorporated into an electric power steering device together with an electric motor, etc., and an auxiliary torque obtained by decelerating the rotation of the electric motor generated in accordance with the steering torque applied to the steering shaft by the worm speed reducer.
- a worm wheel that constitutes the worm speed reducer is externally fitted and fixed to a part of the steering shaft, and the worm of the worm shaft is combined with the worm wheel.
- Both ends of the worm shaft are rotatably supported inside the gear housing by a pair of rolling bearings.
- An electric motor is connected to the gear housing. Of the two ends of the worm shaft, one end on the electric motor side is spline-connected to one end of the rotating shaft of the electric motor.
- a part opposite to the electric motor is provided with a screw hole in a direction orthogonal to the worm shaft, and a nut member is provided at an outer end of the screw hole.
- a spring holding member is provided inside the screw hole so as to be freely displaceable in the axial direction, and one of the pair of rolling bearings is provided on one of the rolling bearings on the side opposite to the electric motor.
- One end surface of the spring holding member is abutted against the outer peripheral surface.
- a worm wheel is attached to the other end of the worm shaft by a coil spring provided between the other end surface of the spring holding member and the nut member, the spring holding member, and the one rolling bearing. The elasticity in the direction toward is given.
- the backlash existing at the joint of the worm speed reducer can be suppressed to a certain extent. Sound generation can be suppressed to some extent.
- a structure for suppressing the generation of rattling noise in the worm speed reducer portion a structure described in Patent Document 2 in addition to the structure described in Patent Document 1 is also known.
- the abnormal noise is more likely to occur when the worm wheel rotates in a predetermined direction.
- the reason will be described below.
- one end of the worm shaft 29 (the left end in FIG. 47 (a) and FIG. 48 (a)) is rotated and slightly rotated by a rolling bearing 85 with respect to a fixed portion (not shown).
- the worm provided at the intermediate portion of the above-mentioned worm shaft 29 is combined with the worm wheel 28. In this state, when the worm shaft 29 is rotationally driven to transmit a driving force from the worm shaft 29 to the worm wheel 28, a reaction force is applied from the worm wheel 28 to the worm shaft 29.
- Patent Document 2 an elastic body is provided between the outer peripheral surface of the pressing body and the inner peripheral surface of the housing.
- a structure for suppressing the generation of the abnormal noise is described.
- the resistance to the axial displacement of the pressing body is increased, and the effect of suppressing abnormal noise due to backlash of the joint may be impaired.
- the worm speed reducer according to the present invention and the electric power steering apparatus incorporating the worm speed reducer according to the present invention have a worm shaft that suppresses generation of rattling noise in the worm speed reducer.
- the elastic member is provided with elasticity via another member, and the other member abuts a portion that regulates the displacement of the other member, thereby suppressing generation of abnormal noise. It was done.
- the preload pad can be easily elastically deformed greatly. Therefore, the impact force applied to the guide surface from the preload pad can be reduced. Therefore, it is possible to more effectively suppress the occurrence of the abnormal noise caused by the contact of the preload pad with the guide surface.
- the direction in which the preload pad can be displaced along the guide surface is defined by the center axis of the worm shaft, and the worm It is inclined with respect to an imaginary plane including the worm provided on the shaft and the joint of the worm wheel.
- the direction of the reaction force applied to the worm shaft from the worm wheel when the electric motor is driven and the direction of displacement of the preload pad along the guide surface differ depending on the rotation direction of the worm wheel.
- the electric power steering apparatus of the present invention is characterized in that a steering wheel is provided at the rear end, a rack combined with the pinion or a member supported by the pinion, and A worm speed reducer having any configuration according to the present invention, an electric motor for rotating and driving the worm shaft, a torque sensor for detecting the direction and magnitude of torque applied to the steering shaft or pinion, and A controller for controlling a driving state of the electric motor based on a signal input from the tonnole sensor.
- the assist shaft is any member of the steering shaft, the pinion, and a sub-pinion that engages with the rack at a position separated from the pinion.
- the elastic body is used as a means for imparting elasticity
- the worm shaft is supported so as to be able to rotate and swing with respect to the gear housing.
- the worm provided at the intermediate portion shall be combined with the worm wheel, and the oscillating center axis of the worm shaft shall be shifted from the center axis of the worm shaft to the worm wheel side. Provide parallel to the central axis.
- the difference between the force required to rotate the steering wheel and the return performance of the steering wheel in both rotation directions is obtained. Can be suppressed.
- the object is to solve the following problem.
- Patent Document 3 describes a worm speed reducer that considers reducing backlash at a joint between a worm wheel and a worm shaft.
- this worm reducer is incorporated in an electric power steering device together with an electric motor 114, and the rotation of the electric motor 114 generated according to the steering torque applied to the steering shaft 113 is worm-driven.
- the assist torque obtained by decelerating with the speed reducer 115 is applied to the steering shaft 113.
- a worm wheel 116 constituting the worm speed reducer 115 is externally fitted and fixed to a part of the steering shaft 113, and a worm 118 of a worm shaft 117 is combined with the worm wheel 116.
- Both ends of the worm shaft 117 are rotatably supported inside the gear housing 119 by a pair of rolling bearings 120a and 120b.
- the base end of the worm shaft 117 (left end in FIG. 50) is connected to one end of the rotary shaft 121 of the electric motor 114 (right end in FIG. 51).
- the elasticity applying means 123 includes an inner cylindrical portion 124 and an outer cylindrical portion 125, each of which is made of metal, and a ring portion 126 made of rubber or synthetic resin connecting these two cylindrical portions 124, 125. It consists of Further, the inner diameter side cylindrical portion 124 is eccentric to the worm wheel 116 side with respect to the outer diameter side cylindrical portion 125.
- the outer cylindrical portion 125 of the elasticity applying means 123 is fixedly fitted in the concave hole 122, and the inner ring 127 of one rolling bearing 120b fixed inside the inner cylindrical portion 124 is fixed to the inner ring 127.
- the tip of the worm shaft 117 is fixed inside. With this configuration, an elastic force is applied to the tip of the worm shaft 117 in the direction of the force (upward in FIGS. 50 and 51) to the worm wheel 116, and the worm shaft 117 swings toward the worm wheel 116. Dynamically displaces.
- the screw hole 128 of the gear housing 119 is provided on one surface (the left end surface in FIG.
- the worm shaft 117 is supported on the gear housing 119 so as to be able to swing.
- the center axis of the oscillating displacement of the worm shaft 117 passes through a point on the center axis of the worm shaft 117, such as the center of a rolling bearing 120a for supporting the base end of the worm shaft 117. If it is provided at a position, there is a problem that a difference occurs in the return of the steering wheel (not shown) in both rotation directions. Another problem is that the difference in the force required for the driver to operate the steering wheel in both directions of rotation increases. The reason for this is explained below.
- the worm shaft 117 is driven to rotate by the electric motor 114 and the driving force is transmitted from the worm shaft 19 to the worm wheel 18 will be considered with reference to the schematic diagrams shown in FIGS. 52 (a) and 52 (b).
- the electric motor 114 is driven to rotate in the opposite direction by the same magnitude.
- the vehicle angle between the ⁇ -year axis 117 and the ⁇ ⁇ -year wheel 116 is set to 90 degrees.
- the axial component Fa of the worm shaft 117 is 1 1
- the component force Fu applied from the worm shaft 117 to the worm wheel 116 in the tangential direction of the pitch circle of the worm wheel 116 has the same magnitude in the opposite direction.
- elasticity applying means 123 (FIGS. 50 and 51) is used. Appropriate elasticity in the direction of force is given.
- the reaction force applied to the worm shaft 117 from the worm wheel 116 is displaced from the center axis of the worm shaft 117 to the worm wheel 116 side, and the worm of the worm shaft 117 It works at the joint with the worm wheel 116. Therefore, when the swing center of the worm shaft 117 is provided at a position passing through the center axis of the worm shaft 117, the swing force of the worm shaft 117 is applied to the worm shaft 117 by the axial component force Fa.
- the dynamic center is the center
- the base end (the left end of FIGS. 53 and 54) of the worm shaft 117 is rotated by a rolling bearing 120a to a fixed portion (not shown) so that the rotation and the center o of the rolling bearing 120a are positioned therein. A slight swing displacement centered on the center is supported. Further, the worm shaft 117 is rotationally driven in the opposite directions in the case shown in FIG. 53 and the case shown in FIG. In such a state, the reaction force between the worm of the worm shaft 117 and the worm wheel 116 is opposite in the axial direction of the worm shaft 117 between the case shown in FIG. 53 and the case shown in FIG. Fa force This worm wheel 116 force is also added to this worm shaft 117.
- a force Fm having a magnitude of 117 acts in the radial direction of the worm shaft 117 at the joint portion.
- the directions of action of the force Fm are opposite to each other in the case shown in FIG. 53 and the case shown in FIG.
- the magnitude of the actual force Fr ′ taking into account the moment M, which acts radially from the worm wheel 116 to the worm shaft 117 at the joint, is
- the worm tooth surface of the worm shaft 117 is easily separated from the tooth surface of the worm wheel 116.
- the force of pressing these tooth surfaces is increased, the rotational torque of the worm wheel 116 and the worm shaft 117 increases.
- the elasticity to be applied to the worm shaft 117 by the elasticity applying means needs to be set to an appropriate predetermined value.
- the worm speed reducer according to the present invention and the electric power steering device incorporating the worm speed reducer generate rattle noise at the joint between the worm of the worm shaft and the worm wheel.
- the swing center axis of the worm shaft is displaced from the center axis of the worm shaft to the worm wheel side in parallel with the center axis of the worm wheel. Provided. Therefore, when the driving force is transmitted from the worm shaft to the worm wheel, despite the fact that a reaction force is applied to the worm shaft from the worm wheel in the axial direction of the worm shaft, the worm shaft is not driven in the axial direction. The moment generated on the worm shaft based on the reaction force can be reduced or reduced to zero. Therefore, the radial reaction force applied from the worm wheel to the worm shaft can be suppressed from fluctuating due to the influence of this moment.
- a straight line that includes the intersection of the pitch circle between the worm of the worm shaft and the worm wheel and that is parallel to the central axis of the worm shaft Pass an axis parallel to the center axis of this worm wheel The center axis of the worm shaft.
- a bearing holder for supporting at least one of a pair of bearings rotatably supporting a portion near both ends of the worm shaft is swung with respect to the gear housing. Supports displacement.
- the one bearing can be supported so as to be capable of swinging displacement with respect to the gear housing while using the one generally used conventionally as the one bearing.
- the cost increase can be suppressed.
- a bearing on the electric motor side of a pair of bearings rotatably supporting a portion near both ends of the worm shaft, a worm of the worm shaft, and a worm of the worm shaft
- a swing center axis of the worm shaft is provided between the joint portion of the wheel.
- a large preload is applied to the joint portion between the worm and the worm wheel of the worm shaft while reducing the swing displacement of the end of the worm shaft on the electric motor side. This makes it possible to more effectively suppress the generation of harsh rattles in this joint.
- the worm shaft is disposed on the opposite side of the worm shaft swing center axis with respect to the joint between the worm shaft and the worm wheel.
- the worm wheel is provided with elasticity applying means for imparting elasticity in the direction of the directional force.
- the amount of elastic deformation of the elastic body constituting the elasticity applying means can be increased, and the magnitude of the elasticity applied to the worm shaft can be easily adjusted.
- the worm shaft A bearing holder for supporting a bearing rotatably supporting a portion near one end of the gear housing is supported by the gear housing so as to be capable of swinging displacement by a swing shaft, and between the gear housing and the swing shaft.
- an elastic material is provided between the bearing holder and the swing shaft.
- the worm speed reducer having the above configuration of the present invention, when rotational vibration is input to the worm wheel, the worm shaft can be easily displaced in the axial direction, and the worm shaft is You can do a rotational movement. For this reason, the force transmitted between the two tooth surfaces can be reduced. As a result, the two flank surfaces can be prevented from separating from each other without increasing the rotation torque of the worm shaft, and the occurrence of the rattling noise can be suppressed. Further, the vibration based on the abutment between the two tooth surfaces can be transmitted to the gear housing, and the generation of abnormal noise due to the vibration can be suppressed.
- a bearing holder for supporting a bearing that rotatably supports a portion near one end of the worm shaft is provided.
- the swinging shaft is supported by the gear housing so as to be capable of swinging displacement, and at least a part is formed of an elastic material between the gear housing and the swinging shaft or between the bearing holder and the swinging shaft. And the rigidity of the elastic ring in the radial direction of the oscillating shaft of the worm shaft is varied in the circumferential direction.
- the rigidity of the elastic ring in the axial direction of the worm shaft is reduced, so that the required rigidity of the entire elastic ring is ensured while maintaining the gear housing.
- the worm shaft can be easily displaced in the axial direction with respect to jing. Therefore, an increase in the rotational torque of the worm shaft can be more effectively suppressed.
- the worm wheel is provided between the worm shaft and the rotating shaft of the electric motor.
- An elasticity imparting means for imparting elasticity in the direction of the directional force is provided.
- a deep groove type having a relatively large internal clearance in the axial direction is used as one of the bearings for supporting the end of the worm shaft on the electric motor side while suppressing the generation of abnormal noise.
- Ball bearings can be used, and costs can be reduced.
- a small number of the pair of bearings that rotatably support portions near both ends of the worm shaft is used.
- an elasticity applying means for imparting a directional force to the worm wheel in the worm wheel.
- a preload is applied to the joint between the worm of the worm shaft and the worm wheel without increasing the total length of the portion formed by connecting the worm shaft and the rotating shaft of the electric motor. Can be granted.
- the swing center of the pair of bearings supporting the portions near both ends of the worm shaft is used.
- the worm shaft can be displaced with respect to the gear housing.
- the end of the worm shaft opposite to the electric motor which does not impair the effect of suppressing the generation of rattling noise at the joint between the worm and the worm wheel, The generation of abnormal noise due to collision with one of the bearings supporting the end can be prevented.
- the worm shaft of the pair of bearings that support portions near both ends of the worm shaft is used.
- a second elastic ring at least part of which is made of an elastic material, between one of the bearings distant from the swing center axis and the gear housing, The swing displacement of the worm shaft is enabled, and the rigidity of the second elastic ring is made different between the one relating to the swing displacement direction of the worm shaft and the one relating to another direction.
- the worm shaft is easily displaced toward the worm wheel while preventing the worm shaft from being displaced in an unintended direction.
- the generation of rattling noise at the joint between the worm wheel and the worm wheel can be suppressed more effectively.
- the worm shaft is swung by an elastic member or a second elastic ring provided between the one bearing and the gear housing.
- a stopper is provided to restrict displacement. According to this preferred configuration, the beam shaft can be prevented from being excessively rocked.
- the rotation shaft of the electric motor and the worm shaft are connected via an elastic material. According to this preferred configuration, it is possible to make it difficult to transmit rotational vibration between the rotating shaft and the worm shaft of the electric motor.
- a small number of the pair of bearings that rotatably support portions near both ends of the worm shaft are used. At least a space is filled between the bearing holder for supporting at least one bearing and the gear housing.
- the worm shaft when the driving force is transmitted between the worm shaft and the worm wheel, the worm shaft is moved based on the reaction force applied from the worm wheel to the worm shaft.
- the bearing holder can be swingably displaced.
- the driving force increases and the reaction force increases, the speed at which the worm shaft separates from the worm wheel tends to increase. In this case, however, the viscosity resistance of the grease also increases.
- the swing displacement of the bearing holder can be suppressed. For this reason, it is easy to prevent the tooth surfaces of the worm of the worm shaft and the worm wheel from separating from each other.
- the bearing holder for supporting at least one of the pair of bearings rotatably supporting the worm shaft near both ends is made of a magnesium alloy.
- the vibration generated on the worm shaft due to the abutment between the tooth surfaces of the worm and the worm wheel of the worm shaft can be easily absorbed by the bearing holder. This vibration can be hardly transmitted.
- the electric power steering apparatus includes a steering shaft provided with a steering wheel at a rear end, a pinion provided at a front end of the steering shaft, and a pinion or a pinion provided at the front end.
- a rack combined with a member supported by a pinion; any one of the worm speed reducers according to the above-described configuration of the present invention; an electric motor for rotating and driving a worm shaft; and a direction of torque applied to the steering shaft or the pinion
- a controller for controlling the driving state of the electric motor based on a signal input from the tonnole sensor.
- the worm wheel is fixed to any one of the steering shaft, the pinion, and a sub-pinion that is coupled to the rack at a position away from the pinion.
- the elastic body is provided with an elastic force in a direction toward the worm wheel to the worm shaft via the preload pad.
- the worm wheel can be freely fixed to the assist shaft.
- the worm shaft is supported inside the gear housing by a first bearing at a portion near one end and by a second bearing at a portion near the other end, and a worm provided at an intermediate portion is combined with the worm wheel. It is assumed that it can swing around the first bearing.
- the second bearing is covered with a synthetic resin cushioning member fixed to the gear housing at least a part of the outer peripheral surface and both side surfaces in the axial direction. It is assumed that the axial displacement is restricted. Further, axial displacement of the worm shaft with respect to the preload pad and the second bearing is allowed.
- Patent Document 4 describes a worm speed reducer that considers reducing backlash at a joint between a worm wheel and a worm of a worm shaft.
- the worm reducer rotatably supports the worm shaft 117 near both ends thereof with respect to the gear housing 119 by a pair of rolling bearings 120a and 120b.
- the pair of rolling bearings 120a and 120b one of the rolling bearings 120b (on the right side in FIG. 55) is elastically pressed against the outer peripheral surface of the outer ring 130 by a spring 132 which is supported by a gear housing 119. ing.
- the distal end of the worm shaft 117 is provided with a directional force on the worm wheel 116 and a resilient force in a direction opposite to the worm wheel 116.
- a cylindrical guide member 134 having a pair of side walls 133, 133 parallel to each other is provided on the inner surface of the one rolling bearing 120b so as to extend in the radial direction of the one rolling bearing 120b. And axial displacement.
- the other end (the left side in FIG. 55) of the pair of rolling bearings 120a and 120b is provided on one surface with a tip surface of a screw ring 129 coupled to a screw hole 128 formed in the gear housing 119.
- the preload applied to the joint at a predetermined value or more.
- the preload is applied in order to suppress generation of rattling noise in the joint portion.
- the preload is equal to or more than a predetermined value, the steering wheel when returning the vehicle from the turning state to the straight traveling state is used. The return performance of this steering wheel, which returns to the neutral state, deteriorates.
- the preload needs to be set within a limited narrow range. Therefore, it is necessary to sufficiently reduce the frictional force acting between the end face of the outer race 130 and the end face of the guide member 134, which greatly affects the preload. However, it is difficult to finely adjust the tightening amount of the screw ring 129 in order to sufficiently reduce the frictional force.
- the worm speed reducer and the electric power steering device incorporating the worm reducer are applied to the joint portion regardless of the axial force applied from the worm wheel to the worm shaft.
- the present invention has been invented to effectively suppress the generation of rattling noise in this joint by making it easy to stably maintain the preload within a limited narrow range.
- the preloading pad for applying elasticity to the worm shaft and the second bearing for supporting the tip end of the worm shaft are provided in the axial direction of the worm shaft. Displacement is allowed. For this reason, even when a worm wheel force or a large axial reaction force is applied to the worm shaft, the reaction force causes the preload pad and the second bearing to be strongly applied to another member in the axial direction of the worm shaft. I can't be pressed. Therefore, by giving elasticity to the worm shaft via the above-mentioned preload pad by the elastic body, the preload applied to the joint portion between the worm wheel and the worm of the worm shaft largely varies due to the influence of the reaction force. Can be prevented.
- this preload can be easily and stably maintained in a limited narrow range for a long period of time, and generation of rattling noise at the joint can be effectively suppressed.
- the cushioning member that regulates the displacement of the second bearing is made of synthetic resin, the frictional force acting between the second bearing and the cushioning member is reduced, so that the second bearing is radially moved. Can be easily displaced. For this reason, it is possible to more effectively suppress the rattling noise at the joint.
- the second bearing covers at least a part of the outer peripheral surface and both sides in the axial direction with the cushioning member, and regulates the axial displacement of the second bearing with respect to the cushioning member. By pressing the worm shaft against the second bearing in the axial direction, the play of the second bearing can be easily suppressed.
- the cushioning member is provided with a notch in a part of the circumferential direction over the entire length in the axial direction.
- the diameter of the shock-absorbing member can be elastically greatly increased, and the second bearing is provided inside the shock-absorbing member to restrict the axial displacement of the second bearing. Can be easily assembled. Further, the above-mentioned cushioning member can easily absorb dimensional errors and assembly errors of components provided around the cushioning member. Further, even when the ambient temperature changes, the dimensional change can be absorbed by the cutout portion provided in the buffer member, and the dimensional change other than the cutout of the buffer member can be suppressed.
- the second bearing is prevented from being displaced in the axial direction of the second bearing with respect to the buffer member, and is allowed to be displaced in the radial direction of the second bearing with respect to the buffer member. It shall have been done.
- an elastic member is provided between the cushioning member and the gear housing or between the cushioning member and the second bearing.
- this more preferable configuration it is possible to easily suppress rattling of the buffer member with respect to the gear housing or rattling of the second bearing with respect to the buffer member. For this reason, it is possible to easily manage the dimensions of each part, and it is easy to maintain the engagement between the worm of the worm shaft and the worm wheel in an appropriate state. Further, when assembling the shock absorbing member to the gear housing or assembling the second bearing to the shock absorbing member, the elastic member can be compressed between these members. For this reason, the work of assembling the cushioning member or the second bearing can be performed while preventing the cushioning member or the second bearing from dropping out of the gear housing or the cushioning member, and this assembling work can be easily performed. You.
- the buffer member comprises a pair of elements having a shape obtained by dividing the buffer member into two by a virtual plane including the central axis of the buffer member. According to this more preferable configuration, the forming operation for obtaining the buffer member can be facilitated, and the operation of assembling the second bearing inside the buffer member can be performed more easily.
- the surface direction of the butted surface of the pair of elements is made to coincide with the direction in which elasticity is applied to the worm shaft by the elastic body. According to this preferred configuration, the swing displacement of the worm shaft can be more easily performed.
- a steering shaft provided with a steering wheel at the rear end, a pinion provided at the front end side of the steering shaft, and the pinion or the pinion.
- Racks and books combined with the supporting members Any one of the worm speed reducer according to the above-described configuration of the invention, an electric motor for rotationally driving the worm shaft, a torque sensor for detecting the direction and magnitude of the tonnolek applied to the steering shaft or the pinion, A controller for controlling a driving state of the electric motor based on a signal input from the tonnole sensor, wherein an assist shaft includes the steering shaft, the pinion, and the rack at a position away from the pinion. And any one of a sub-pinion and a sub-pinion.
- FIG. 19 shows a first embodiment of the present invention.
- the electric power steering apparatus includes a steering shaft 2 as an assist shaft having a steering wheel 1 fixed to a rear end portion, a steering column 15 through which the steering shaft 2 can pass, and a steering shaft.
- a worm reducer 16 for applying an auxiliary torque to the steering shaft 2, a pinion 11 (see FIG. 46) provided at the front end of the steering shaft 2, and the pinion 11 or a member supported by the pinion 11 are combined.
- Rack 12 see FIG. 46
- torque sensor 3 see FIG. 46
- electric motor 31, and controller 6 see FIG. 46).
- the steering shaft 2 is formed by combining an outer shaft 17 and an inner shaft 18 by a spline engaging portion so that rotational force can be transmitted and displacement in the axial direction is possible.
- the front end of the outer shaft 17 and the rear end of the inner shaft 18 are spline-engaged and connected via a synthetic resin. Therefore, when the outer shaft 17 and the inner shaft 18 collide with each other, the synthetic resin can be broken to reduce the overall length.
- the cylindrical steering column 15 that passes through the steering shaft 2 is formed by combining an outer column 19 and an inner column 20 in a telescopic shape. It has a so-called collapsible structure in which the overall length is reduced while absorbing the energy generated by the device.
- the front end of the inner column 20 is connected and fixed to the rear end face of the gear housing 22.
- the inner shaft 18 is inserted into the inside of the gear housing 22, and the front end of the inner shaft 18 projects from the front end surface of the gear housing 22.
- the steering column 15 is mounted on the dashboard by a support bracket 24 at an intermediate portion thereof. And a portion of the vehicle body 26, such as the underside of the vehicle. A not-shown locking portion is provided between the support bracket 24 and the vehicle body 26, and when a shock in the direction of a forward force is applied to the support bracket 24 in a forward direction, the support bracket 24 is connected to the locking portion. So that it is out of the way.
- the upper end of the gear housing 22 is also supported by a part of the vehicle body 26. Further, by providing a tilt mechanism and a telescopic mechanism, the front and rear positions and the height position of the steering wheel 1 can be freely adjusted. Such a tilt mechanism and a telescopic mechanism are well known in the related art, and are not characteristic features of the present embodiment.
- the portion of the front end of the inner shaft 20 that protrudes from the front end surface of the gear housing 22 is connected to the rear end of the intermediate shaft 8 via the universal joint 7.
- An input shaft 10 of a steering gear 9 is connected to a front end of the intermediate shaft 8 via another universal joint 7.
- the pinion 11 is connected to the input shaft 10.
- the rack 12 is combined with the pinion 11.
- a vibration absorbing device may be provided in each of the universal joints 7.
- the worm speed reducer 16 includes a worm wheel 28 that can be fitted and fixed to a part of the inner shaft 18, an worm shaft 29, a torsion coil spring 30, and a preload pad 70. Further, the worm speed reducer 16 includes first to fourth ball bearings 34 to 37, each of which is a single-row deep groove type.
- the torque sensor 3 is provided around an intermediate portion of the steering shaft 2, and detects the direction and magnitude of the tonnolek applied to the steering shaft 2 from the steering wheel 1, and detects the detected value. Is sent to the controller 6. Then, in response to the detection signal, the controller 6 sends a driving signal to the electric motor 31 to generate an auxiliary tonnole with a predetermined size in a predetermined direction.
- the worm wheel 28 and the worm shaft 29 are provided inside the gear housing 22, and the worm wheel 28 and the worm 27 provided at an intermediate portion of the worm shaft 29 are combined.
- the electric motor 31 includes a case 23 fixedly connected to the gear housing 22, a permanent magnet stator 39 provided on the inner peripheral surface of the case 23, and a A rotating shaft 32 provided inside the base 23 and a rotor 38 provided at an intermediate portion of the rotating shaft 32 so as to face the stator 39.
- the first ball bearing 34 is formed between an inner peripheral surface of a concave hole 41 provided at the center of a bottom plate portion 40 constituting the case 23 and an outer peripheral surface of a base end portion of the rotating shaft 32.
- the base end (the left end in FIGS. 2 and 3) of the rotation shaft 32 is rotatably supported by the case 23 with respect to the case 23.
- the second ball bearing 35 is provided between the inner peripheral edge of the partition 42 provided on the inner peripheral surface of the intermediate portion of the case 23 and the outer peripheral surface of the intermediate portion of the rotary shaft 32. In contrast, the intermediate portion of the rotating shaft 32 is rotatably supported.
- the rotor 38 is formed by winding a coil 45 around slots 44 provided at a plurality of circumferential positions on the outer peripheral surface of a core 43 made of a laminated steel plate provided at an intermediate portion of the rotating shaft 32. Also, a commutator 46 for energizing the coil 45 is provided at a portion near the tip of the rotary shaft 32 (a portion near the right end in FIGS. 2 and 3) and between the rotor 38 and the partition wall portion 42. RU
- a brush holder 47 is fixed to a portion of the inner peripheral surface of the case 23 facing the commutator 46.
- the brush 48 is accommodated in the brush holder 47 so as to be displaceable in the radial direction of the case 23.
- the brush 48 is electrically connected to a terminal of a force brush (not shown) provided on the outer peripheral surface of the case 23.
- the brush 48 has a spring 49 supported in the brush holder 47 to give elasticity toward the inner diameter side of the case 23. Therefore, the inner end surface of the brush 48 elastically slides on the outer peripheral surface of the commutator 46.
- the commutator 46 and the brush 48 constitute a rotor phase detector for switching the direction of the exciting current to the coil 45.
- a female spline portion 50 provided on the inner peripheral surface of the base end portion (the left end portion in FIGS. 2 and 4) of the worm shaft 29 is combined with a male spline portion 51 provided on the distal end portion of the rotary shaft 32.
- the ends of the shafts 29 and 32 are connected to each other by a spline engagement portion 33 formed by engagement. With this configuration, the worm shaft 29 rotates together with the rotation shaft 32.
- the third ball bearing 36 rotatably supports the base end of the worm shaft 29 inside the gear housing 22.
- an outer ring 57 constituting the third ball bearing 36 is internally fitted and fixed to an inner peripheral surface of a support hole 59 provided in a part of the gear housing 22.
- one axial end face of the outer ring 57 (the right end face in FIGS. 2 and 4) is The outer ring 57 is pressed against a step 58 provided on the peripheral surface, and the other end surface in the axial direction of the outer ring 57 (the left end surface in FIGS. 2 and 4) is held down by a retaining ring 88 retained on the inner peripheral surface.
- the inner ring 52 constituting the third ball bearing 36 is externally fitted on a portion of the outer peripheral surface of the worm shaft 29 near the base end, which portion coincides with the spline engaging portion 33 in the axial direction.
- the axial center position of the spline engagement portion 33 and the axial center position of the third ball bearing 36 are substantially matched. Further, by providing a minute gap between the inner peripheral surface of the inner ring 52 and the outer peripheral surface of the worm shaft 29, the worm shaft 29 can be inclined in a predetermined range with respect to the third ball bearing 36.
- the inner ring 52 is screwed and fixed to both axial end surfaces of the inner ring 52, the side surface of a flange 53 provided on the outer peripheral surface near the base end of the worm shaft 29, and the male screw portion 54 provided at the base end of the worm shaft 29.
- a plurality of disc springs 56 are provided between the nut 55 and the inner end surface thereof.
- the inner ring 52 is elastically held between the side surface of the flange 53 and the inner end surface of the nut 55 (the left end surface in FIGS. 2 and 4).
- the worm shaft 29 can be elastically displaced relative to the third ball bearing 36 in a predetermined range in the axial direction.
- a four-point contact type ball bearing is used as the third ball bearing 36.
- the fourth ball bearing 37 rotatably supports the tip of the worm shaft 29 (the right end in FIGS. 2, 4, and 5) inside the gear housing 22.
- an outer ring 60 constituting the fourth ball bearing 37 is fixed to a holder 61 fixed inside the gear housing 22.
- the holder 61 has an L-shaped cross section and is formed in an annular shape.
- the outer ring 60 is fixed inside.
- a bush 64 made of an elastic material is externally fitted to a large-diameter portion 63 provided on a portion of the outer peripheral surface of the worm shaft 29 close to the front end and separated from the worm 27.
- the bush 64 has an L-shaped cross section and is entirely cylindrical.
- the large-diameter portion 63 of the worm shaft 29 is loosely inserted through the inside of the ⁇ 64, and the worm shaft 29 is axially moved from one axial end surface of the boss 64 (the right end surface in FIGS. 2, 4, and 5).
- the tip of 29 is projected.
- An inner ring 65 constituting the fourth ball bearing 37 is externally fitted and fixed to the axially intermediate portion of the bush 64.
- one end face in the axial direction of the inner ring 65 (left end face in FIGS. 2, 4, and 5) is provided on the other end in the axial direction of the bush 64 (left end in FIGS. 2, 4, and 5).
- the inner ring 65 is positioned in the axial direction by abutting against the inner side surface of the facing flange 67.
- a tapered surface 89 is provided between the large diameter portion 63 provided on the worm shaft 29 and the small diameter portion 68 provided at a portion deviated from the large diameter portion 63 on the distal end side. Further, a tapered surface 109 is provided at a continuous portion between the small diameter portion 68 and the distal end surface of the worm shaft 29. A part of the preload pad 70 disposed between the other end surface of the holder 61 fixed to the gear housing 22 (the right end surface in FIGS. 2, 4 and 5) and the bottom surface of the concave hole 72 provided in the gear housing 22. The small diameter portion 68 is inserted without looseness. As shown in detail in FIG.
- the preload pad 70 is formed by injection molding synthetic resin mixed with a solid lubricant, for example, to remove one side portion at two locations on the radially opposite side of the portion near the outer periphery of the cut cylinder. It is made in a shape like that. Also, of the flat portion 91 provided on the radially opposite side of the outer peripheral surface of the preload pad 70, a portion closer to one side of the one end in the longitudinal direction (the lower end in FIG. 7-9) (closer to the rear side in FIG. 7-9). Part) has an arm 92.
- a small-diameter portion 68 of the worm shaft 29 is provided inside a through hole 71 provided in a center portion of the preload pad 70 in the width direction (the left-right direction in FIGS. 6-9) so as to penetrate in the axial direction. It can be inserted freely without sticking.
- tapered surfaces 93a and 93b whose diameters are increased toward the opening end are provided at portions near both ends in the axial direction of the through hole 71, respectively.
- the cross-sectional shape of the inner peripheral surface of the through-hole 71 in the axially intermediate portion in the free state is a substantially equilateral triangular shape such that two adjacent linear portions are connected to each other by a curved portion. I have.
- the outer peripheral surface of the small-diameter portion 68 of the worm shaft 29 abuts at three positions at equal intervals in the circumferential direction on the inner peripheral surface of the intermediate portion of the through hole 71 where the intermediate portion of each linear portion is located.
- the contact portion is 94.
- each of the contact portions 94 is located at a target position with respect to a virtual plane (FIG. 7) including the central axis of the preload pad 70 and passing through the central portion in the width direction.
- one contact portion 94 located at the center in the width direction of the preload pad 70 on the inner peripheral surface of the axially intermediate portion of the through hole 71 and an opposite side with respect to the center axis of the through hole 71
- a recess 95 is formed in the portion.
- the recess 95 is formed in a part of the preload pad 70 in the circumferential direction. The stiffness of the portion corresponding to is reduced, and this portion is easily elastically deformed.
- a discontinuous portion 90 for communicating the inner and outer peripheral surfaces of the preload pad 70 with each other is provided at a position shifted to one side (the right side in FIGS. 7-9) with respect to the virtual plane ⁇ .
- a first partial cylindrical surface portion 104 is provided on a portion opposite to the worm wheel 28 (the lower side in FIG. 79), and the worm wheel 28 side (FIG. 7-9).
- a second partial cylindrical surface portion 105 concentric with the first partial cylindrical surface portion 104 is provided in each of the (upper) portions.
- a small width projection 106 is provided at a circumferentially intermediate portion of the first partial cylindrical surface portion 104, and a distal end surface of the projection 106 is connected to the third partial cylindrical surface portion 107 concentric with the first partial cylindrical surface portion 104.
- a locking projection 108 protruding to the outer diameter side is provided.
- Such a preload pad 70 is combined with the honoreda 61, which can be freely fitted and fixed to the gear housing 22 (Figs. 2, 4-16), as shown in detail in Figs. Also, on the other surface in the axial direction of the holder 61 (the front side surface in FIG. 9), a total of four first and second projections 97 and 98, two each, are provided around the opening of the through hole 96. It is divided and formed at four locations. Each of the first protrusions 97 is on the worm wheel 28 side (the upper side of FIGS. 2, 4, and 5), and each second protrusion 98 is on the opposite side of the worm wheel 28 (FIG. 2, FIG. 4 and 5).
- partial cylindrical surface portions 99 concentric with each other are provided on the outer diameter side surfaces of the first and second protrusions 97 and 98, respectively.
- a first locking projection 100 is provided on a side of the second projection 98 near the front end opposite to the worm wheel 28.
- the holder 61 and the preload pad 70 are combined, and the torsion coil spring 30 is provided around these two members 61, 70. That is, the preload pad 70 is arranged inside the first and second protrusions 97 and 98 provided on the holder 61, and one side of each of the second protrusions 98 (see FIG. Side), each arm 92 provided on the preload pad 70 is locked. Also, one side (the back side in FIGS. 8 and 9) of the first locking projection 100 provided on each of the second projections 98 is opposed to each of the arms 92 via a minute gap. I have.
- a pair of locking portions 73 provided at two positions on opposite ends in the radial direction at both ends of the torsion coil spring 30 are provided on a part of the holder 61, and the first and second adjacent portions are provided. Sudden The main body portion of the torsion coil spring 30 is disposed on the outer diameter side surface of each of the first and second protrusions 97 and 98 and the outer peripheral surface of the preload pad 70 while being disposed between the portions 97 and 98. Coil part). The locking portion 73 of the torsion coil spring 30 is locked to the other side surface (the upper side surface in FIGS. 6, 8, and 9) of each second protrusion 98 provided on the holder 61.
- the second locking projections 101 provided at the tip of the other side surface of each of the second projections 98 prevent the locking portions 73 from coming off. Then, the inner peripheral edge of the main body of the torsion coil spring 30 is elastically pressed against the third cylindrical surface portion 107 provided on the opposite side to the worm wheel 28 (the lower side of FIG. 2, 419). ing.
- each flat portion 91 provided on the preload pad 70 is minutely attached to the inner diameter side surface of each of the first and second protrusions 97 and 98 provided on the holder 61. They face each other via a gap.
- the displacement of the preload pad 70 in the width direction (the front-back direction in FIGS. 2, 4, and 5 and the left-right direction in FIG. 69) of the preload pad 70 is regulated by these inner diameter side surfaces.
- the inner diameter side surfaces of the first and second projections 97 and 98 correspond to the guide surfaces.
- the holder 61 is internally fitted and fixed to a part of the gear housing 22.
- a small-diameter portion 68 provided at the tip of the worm shaft 29 is inserted into a through hole 71 provided in the preload pad 70.
- the tip of the worm shaft 29 is directed toward the worm wheel 28 from the torsion coil spring 30 via the preload pad 70 (upward in FIGS. 2, 4, and 5). Is given.
- the center axis of the through hole 71 is on one side (with respect to the center axis of the holder 61). (Fig. 4-1 upper side).
- the diameter of the torsion coil spring 30 is increased by the third cylindrical surface portion 107 provided in the preload pad 70.
- the torsion coil spring 30 tends to resiliently return in the direction of rewinding (reducing the diameter), and from the torsion coil spring 30 to the tip of the worm shaft 29 via the preload pad 70, the worm wheel 28 , And elasticity in the direction of movement are provided.
- the distance between the center axes of the inner shaft 18 to which the worm wheel 28 is externally fixed and the worm shaft 29 is reduced in nature.
- the tooth surfaces of the worm 27 of the worm shaft 29 and the worm wheel 28 come into contact with each other with the force preload applied.
- the distal end of the worm shaft 29 is displaced toward the recess 95 inside the through hole 71 provided in the preload pad 70 based on the elasticity of the torsion coil spring 30, whereby the preload pad
- the preload pad 70 is elastically deformed so as to increase the interval between both sides of the preload pad 70 sandwiching the recess 95.
- each flat surface portion 91 of the preload pad 70 elastically expands in a C-shape, and each flat surface portion 91 is provided on the inner diameter side surface of each of the first and second protrusions 97 and 98 provided on the holder 61.
- the gaps between the flat portions 91 and the inner diameter side surfaces are reduced elastically.
- the contact portion between the outer peripheral surface of the preload pad 70 and the inner peripheral edge of the torsion coil spring 30 is formed in a partially arcuate shape, and the length of the contact portion is reduced.
- the length of the torsion coil spring 30 is sufficiently small with respect to the length of one turn.
- the preload pad 70 is attached to the tip of the worm shaft 29 by the torsion coil spring 30.
- the elasticity in the direction toward the worm wheel 28 is provided through the worm wheel 28. Therefore, it is possible to apply a preload to the joint between the worm wheel 28 and the worm shaft 29 with an inexpensive structure, and it is possible to suppress the generation of rattling noise at the joint.
- the pressing force is also controlled by the inner diameter side surfaces of the first and second projections 97 and 98 provided on the holder 61 fixed to the gear housing 22 in the width direction of the preload pad 70. Displacement is regulated.
- the tip of the worm shaft 29 is displaced toward the concave portion 95 inside the through hole 71 provided in the preload pad 70, and the preload pad 70 itself is elastically deformed. . Then, by making each flat portion 91 of the preload pad 70 elastically abut against the inner diameter side surface, the gap between each flat portion 91 and the inner diameter side surface is reduced. ing. Therefore, when the electric motor 31 (FIGS. 14) is driven, despite the reaction force in the direction indicated by the arrow A in FIG. 70 can be prevented from strongly abutting against the inner diameter side surfaces of the first and second projections 97 and 98, and generation of unpleasant noise (sound noise) can be suppressed. Also, by suppressing the generation of the abnormal noise, the effect of suppressing the rattle noise is not impaired.
- the preload pad 70 is made of a synthetic resin, the end of the worm shaft 29 is inserted into a through hole 71 formed in the preload pad 70.
- the preload pad 70 can be easily elastically deformed, and this insertion work can be easily performed.
- the surface of one turn of each wire element constituting the torsion coil spring 30 and the surface of another wire element adjacent to each wire element are in axial contact with each other. In such a case, the friction at the contact portion causes the elasticity applied to the worm shaft 29 by the torsion coil spring 30 to be changed inappropriately.
- an axial gap is provided between the surface of the above-mentioned one winding wire element and the surface of another wire element adjacent to each wire element. Since the torsion coil spring 30 is not a close-wound spring, the worm shaft 29 can be given a predetermined elasticity more stably.
- the locking projection 108 protruding to the outer diameter side is provided on the outer peripheral surface of the end portion of the preload pad 70, the torsion is performed from the outer peripheral surface of the preload pad 70.
- the coil spring 30 can be prevented from falling off, and the displacement of the torsion coil spring 30 in the axial direction of the preload pad 70 can be restricted.
- FIG. 10 shows a second embodiment of the present invention.
- the position of the contact portion 94a between the inner peripheral surface of the through hole 71a provided in the preload pad 70 and the outer peripheral surface of the small diameter portion 68 provided at the tip of the worm shaft 29 is determined by the above-described first position. It is different from the example. That is, in the case of the present embodiment, the worm wheel 28 (see FIG. 4-15) force also tends to increase the reaction force applied to the worm shaft 29.
- the worm shaft 29 and the preload pad 70 are located at three equally spaced circumferential positions in the direction of the arrow A in FIG.
- the amount of elastic deformation of the preload pad 70 can be increased, and the preload pad 70 can be prevented from being largely displaced in the direction of the arrow a due to the reaction force applied to the worm shaft 29. Accordingly, it is possible to prevent a part of the preload pad 70 from strongly abutting against the inner diameter side surfaces of the first and second projections 97 and 98, and to prevent the preload pad 70 from coming into contact with the inner diameter side surfaces. The impact force applied to the inner surface can be reduced, and the generation of abnormal noise caused by the abutment of the preload pad 70 against these inner side surfaces can be suppressed more effectively.
- Other configurations and operations are the same as those in the first embodiment described above, and therefore, the same reference numerals are given to the same components, and the duplicate description will be omitted.
- FIGS. 11 and 12 show a third embodiment of the present invention.
- the preload pad 70a is configured by combining two elements 110a and 110b that are separate from each other. These two elements 110a and 110b are provided with a discontinuous portion 90 of the preload pad 70 constituting the structure of the first embodiment shown in FIG. Etc.) with respect to the central axis of the preload pad 70 at a position opposite to the discontinuous portion 90. That is, each of the elements 110a and 110b is provided with a substantially semi-cylindrical concave portion 111 in the longitudinal direction (vertical direction in FIGS. 11 and 12), which is opposed to each other, at a portion near both ends in the longitudinal direction.
- a plane portion 91 and an arm portion 92 are provided on the other side surface of each of the elements 110a and 110b opposite to each other. Then, in a state where these elements 110a and 110b are combined with each other while the flat portions 112a and 112b provided on the one side surfaces are abutted against each other, the portions where the concave portions 111 are opposed to each other are used in the first embodiment described above.
- a through hole having the same shape as the through hole 71 provided in the preload pad 70 is formed.
- a first partial cylindrical surface portion 104a is provided on a portion opposite to the worm wheel 28 (see FIGS. 2, 4, and 5) (the lower side of FIGS. 11 and 12).
- an arc-shaped second partial cylindrical surface portion 105a concentric with the first partial cylindrical surface portion 104a is provided on the worm wheel 28 side (upper side in FIGS. 11 and 12).
- a small width projection 106a is provided at one end in the width direction of each of the first partial cylindrical surface portions 104a facing each other, and the distal end surface of each of the projections 106a is connected to the first partial cylindrical surface portion 104a.
- the third partial cylindrical surface 107a is concentric with 104a.
- the pair of elements 110a, 110b, each configured as described above, and the holder 61 are combined, and a torsion coil spring 30 is provided around each of the members 110a, 110b, 61. That is, the pair of elements 110a and 110b are arranged inside the first and second protrusions 97 and 98 provided on the holder 61, and one side of each of the second protrusions 98 (FIG. 12).
- the arm 92 provided on each of the above elements 110a and 110b is locked to the lower side of FIG. Further, one side surface (the back side surface in FIG. 12) of the first locking projection 100 provided on each of the second projections 98 is opposed to each of the arms 92 via a minute gap.
- a pair of locking portions 73 provided at two positions on the opposite sides in the radial direction at both ends of the torsion coil spring 30 are provided on a part of the holder 61.
- the torsion coil is formed on the outer diameter side surface of each of the first and second protrusions 97 and 98 and the outer peripheral surface of each of the elements 110a and 110b.
- the main body of the spring 30 is fitted outside.
- the locking portion 73 of the torsion coil spring 30 is locked to the other side surface (the upper side surface in FIG. 12) of each second protrusion 98 provided on the holder 61.
- the inner peripheral edge of the main body of the torsion coil spring 30 is elastically pressed against the third cylindrical surface 107a provided on each of the elements 110a and 11 Ob.
- the flat portion 91 provided on each of the elements 110a and 110b is connected to the inner diameter side surface of each of the first and second protrusions 97 and 98 provided on the holder 61. Are opposed to each other via a minute gap.
- the elements 110a and 110b restrict the displacement of the elements 110a and 110b in the width direction (left and right directions in FIGS. 11 and 12) by their inner diameter side surfaces. Is done.
- the holder 61 is inserted into a part of the gear housing 22 (see Figs. 1 and 2 and the like). Secure. After the holder 61 is fixed to the gear housing 22, the small-diameter portion 68 (see FIG. 4-17) provided at the tip of the worm shaft 29 is combined with the recesses 111 of the elements 110a and 110b. Into the through hole. With this configuration, the front end of the worm shaft 29 is provided with an elastic force in the heading direction from the torsion coil spring 30 to the warm wheel 28 via the elements 110a and 110b. Then, the tooth surface between the arm 27 (see FIGS. 2, 4, and 5) of the worm shaft 29 and the worm wheel 28 comes into contact with each other in a state where a preload is applied.
- the tip of the worm shaft 29 is displaced inside the through hole 71 on the opposite side to the worm wheel 28, thereby causing the elements 110a, 110b
- Each of the flat portions 91 elastically abuts on the inner diameter side surface of each of the first and second protrusions 97 and 98 provided on the holder 61, so that each of the flat portions 91 and the inner diameter side are formed. The gap with the side is reduced.
- FIGS. 13-14 show a fourth example of the embodiment of the present invention.
- the installation directions of the holder 61, the preload pad 70, and the torsion coil spring 30 are different from those of the first embodiment shown in FIGS. It has shifted. That is, the direction indicated by the arrow C in FIG. 13, which is the direction in which the preload pad 70 can be displaced along the inner diameter side surface of each of the first and second projections 97 and 98 provided on the holder 61, The central axis of axis 29 and this It is inclined by an angle ⁇ with respect to an imaginary plane ⁇ (FIG. 13) including a joint between the worm provided on the worm shaft 29 and the worm wheel 28 (see FIGS.
- the direction of the reaction force applied to the worm shaft 29 from the worm wheel 28 when driven by the electric motor 31 differs depending on the rotation direction of the worm wheel 28. 13, the direction indicated by an arrow A and a mouth, and the direction indicated by an arrow C in FIG. 13 which is the displacement direction of the preload pad 70 along the inner diameter side surface of each of the first and second protrusions 97 and 98.
- the angle ⁇ (FIG. 13) formed by the arrow A and the direction indicated by the mouth is substantially equal. It is bisected.
- the driving force of the electric motor 31 is the same in the structure of the first embodiment shown in FIG.
- the magnitude of the reaction force applied from the worm wheel 28 to the worm shaft 29 substantially the same regardless of the direction of this reaction force, the amount of elastic deformation of the preload pad 70 based on this reaction force is The difference due to the difference in the direction can be reduced.
- the direction of these reaction forces (the direction indicated by the arrow in FIG. 7 and the direction of the mouth), the center axis of the worm shaft 29, and the The angle formed between the worm and the virtual plane surface (FIG. 7) including the joint portion of the worm wheel 28 is substantially equal. Therefore, unlike the case of the fourth embodiment shown in FIGS.
- the preload pad 70 can be displaced along the inner diameter side surfaces of the first and second projections 97 and 98 provided on the holder 61. Connect the direction between the center axis of the worm shaft 29 and the joint. It is not necessary to incline with respect to the virtual plane ⁇ .
- the distance d between the joint portion and the swing center ⁇ of the worm shaft 29 in the radial direction of the worm shaft 29, and the joint portion and the swing center o By sufficiently reducing the ratio d / L of the worm shaft 29 to the distance L in the axial direction of the worm shaft 29, the magnitude of Fr can be sufficiently reduced.
- the present invention is not limited to such a structure.
- a pin provided at the lower end of the pinion shaft is engaged with a pinion gear provided separately from the pinion shaft in a longitudinal direction of the pinion gear, and the displacement in the longitudinal direction of the pinion gear is engaged.
- a structure incorporating a so-called variable speed gear ratio mechanism (VGS) that combines a pinion gear and a rack to change the ratio of the displacement of the rack to the rotation angle of the steering shaft according to the vehicle speed, It is better to combine it with the structure.
- the present invention is not limited to the structure in which the electric motor is provided around steering shaft 2.
- a structure in which an electric motor 31 is provided around a pinion 11 (see FIG. 46) to be combined with the rack 12 may be employed.
- a worm wheel constituting the worm speed reducer 16 is fixed to the pinion 11 or a part of a member supported by the pinion 11.
- the torque sensor 3 can be provided around the pinion 11, not around the steering shaft 2.
- the electric motor 31 can be provided around the sub-pinion 75 combined with the above.
- the worm wheel fixed to the sub-pinion 75 and the worm shaft 29 are combined.
- the torque sensor 3 can be provided around the pinion 11.
- the vibration transmitted from the ground to the pinion 11 via the wheels is prevented from being transmitted to the steering wheel 1 at the intermediate portion of the intermediate shaft 8.
- a buffer device 76 is provided.
- the shock absorber 76 is configured by combining an inner shaft and an outer shaft in a telescope shape, and connecting an elastic material between end peripheral surfaces of both shafts.
- the assist shaft of the present invention can be any member of the steering shaft, the pinion, and the sub-pinion that is engaged with the rack at a position away from the pinion. .
- the brush 48 and the commutator 46 are provided with a rotor phase detector, which constitutes the electric motor 31 and switches the direction of the exciting current sent to the coil 45. 3).
- the present invention is not limited to such a structure.
- the rotor phase detector is constituted by a permanent magnet encoder 78 fixed to the rotating shaft 32 and a Hall IC 77.
- the electric motor 31 may have a so-called brushless structure.
- the stator 39a is composed of a core 82 made of laminated steel sheet fixed to the inner peripheral surface of the case 23, and a coil 83 wound around a plurality of portions of the core 82.
- the rotor 38a is constituted by a permanent magnet 84 fixed to the outer peripheral surface of the intermediate portion of the rotating shaft 32.
- the magnetic force of the stator 39a can be switched by providing a vector control device for controlling the increase or decrease of the magnitude of the current sent to the stator 39a.
- the worm speed reducer of the present invention is not limited to those used for such applications, and is an electric linear actuator that is incorporated in various mechanical devices such as an electric bed, an electric table, an electric chair, and a lifter. It can also be used by incorporating it into other devices.
- a worm reducer is connected to this electric linear actuator.
- the motor is incorporated in the motor, the rotation of the electric motor is reduced by the worm speed reducer, then taken out to the rotating shaft, and the output shaft provided around the rotating shaft is expanded and contracted via a ball screw or the like.
- the present invention can be applied to a worm speed reducer incorporated in such an electric linear actuator.
- the worm reduction gear and the electric power steering device of the present invention are configured and operated as described above, and thus constitute this worm reduction gear that suppresses generation of rattling noise in the worm reduction gear.
- FIG. 18-24 shows the fifth embodiment of the present invention.
- the electric power steering apparatus includes a steering shaft 2 having a steering wheel 1 fixed to a rear end, a steering column 15 through which the steering shaft 2 can be inserted, and an auxiliary tonnolek provided to the steering shaft 2.
- Worm gear reducer 16a a pinion 11 provided on the front end side of the steering shaft 2 (see FIG. 46), and a rack 12 combined with the pinion 11 or a member supported by the pinion 11 (see FIG. 46).
- a torque sensor 3 see FIG. 46
- an electric motor 31 and a controller 6 see FIG. 46).
- the steering shaft 2 is formed by combining an outer shaft 17 and an inner shaft 18 by a spline engaging portion so that rotational force can be transmitted and displacement in the axial direction is possible.
- the front end of the outer shaft 17 and the rear end of the inner shaft 18 are spline-engaged and connected via a synthetic resin. Therefore, when the outer shaft 17 and the inner shaft 18 collide with each other, the synthetic resin can be broken to reduce the overall length.
- the cylindrical steering column 15 passing through the steering shaft 2 is formed by combining an outer column 19 and an inner column 20 in a telescopic shape. It has a so-called collapsible structure in which the overall length is reduced while absorbing the energy generated by the device.
- the front end of the inner column 20 is connected and fixed to the rear end face of the main body 135 of the main body 135 and the cover 136 constituting the gear housing 22a.
- the gear housing 22a is formed by connecting the cover 136 to a front end of the main body 135 by bolts or the like (not shown).
- the inner shaft 18 is inserted into the inside of the gear housing 22a, and the front end of the inner shaft 18 projects from the front end surface of the cover 136.
- the steering column 15 has an intermediate portion supported by a support bracket 24 on a part of the vehicle body 26 such as the lower surface of a dashboard. Further, a not-shown locking portion is provided between the support bracket 24 and the vehicle body 26, and when a shock is applied to the support bracket 24 in a forward or backward direction, the support bracket 24 is moved to the above position. Remove from the locking part.
- the upper end of the gear housing 22a is also supported by a part of the vehicle body 26. Further, by providing a tilt mechanism and a telescopic mechanism, the front-rear position and the height position of the steering wheel 1 can be freely adjusted. Such a tilt mechanism and a telescopic mechanism are well known in the related art, and are not characteristic features of the present embodiment, so that detailed description will be omitted.
- the inner shaft 18 is constructed by connecting a first inner shaft 138 and a second inner shaft 139 by a torsion joint 140 (FIGS. 19 and 20).
- the torsion bar 140 passes through the inside of the second inner shaft 139, and the rear end (right end in FIG. 20) of the torsion bar 140 is connected to the front end of the first inner shaft 138 (FIG. 20).
- the front end of the torsion bar 140 (the left end in FIG. 20) is connected to the front end of the second inner shaft 139 (the left end in FIG. 20).
- the torque sensor 3 is applied to the steering shaft 2 from the steering wheel 1 based on the relative rotation direction and the relative rotation amount of the first and second inner shafts 138 and 139 based on the torsion of the torsion bar 140.
- the direction and magnitude of the torque are detected, and a signal (detection signal) representing the detected value is sent to the controller 6.
- the controller 6 sends a driving signal to the electric motor 31 in response to the detection signal, and generates an auxiliary torque of a predetermined magnitude in a predetermined direction.
- the portion of the front end of the second inner shaft 139 that protrudes from the front end surface of the cover 136 constituting the gear housing 22a is connected to the intermediate shaft 8 (FIG. 18) via the universal joint 7. Connected to the rear end. At the front end of this intermediate shaft 8, another universal joint The input shaft 10 (FIG. 18) of the steering gear 9 is connected via 7. The pinion 11 is connected to the input shaft 10. The rack 12 is combined with the pinion 11. Incidentally, in order to prevent the vibration applied to the intermediate shaft 8 from the ground via the wheels from being transmitted to the steering wheel 1, a vibration absorbing device can be provided in each of the universal joints 7.
- the worm speed reducer 16a includes a worm wheel 28 that can be externally fixed to a part of the second inner shaft 39, a worm shaft 29, and elasticity applying means 137.
- the elasticity applying means 137 includes a torsion coil spring 141 and a preload pad 142.
- the worm wheel 28 and the worm shaft 29 are provided inside the gear housing 22a, and the worm wheel 28 and the worm 27 provided at an intermediate portion of the worm shaft 29 are combined.
- the electric motor 31 is provided with a case 23 which is fixedly connected to the gear housing 22a, a permanent magnet stator 39 (FIG. 21) provided on the inner peripheral surface of the case 23, and an inner side of the case 23.
- the rotating shaft 32 is provided, and a rotor 38 (FIG. 21) is provided at an intermediate portion of the rotating shaft 32 so as to face the stator 39.
- a first ball bearing is provided between the inner peripheral surface of the concave hole 41 provided at the center of the bottom plate portion 40 constituting the case 23 and the outer peripheral surface of the base end portion of the rotating shaft 32.
- a base end (the left end in FIGS. 19 and 21) of the rotating shaft 32 is rotatably supported by the case 23 with respect to the case 23.
- a second ball bearing 35 is provided between the inner peripheral edge of the partition wall 42 provided on the inner peripheral edge of the intermediate portion of the case 23 and the outer peripheral surface of the intermediate portion of the rotary shaft 32. The intermediate portion of the rotating shaft 32 is rotatably supported.
- a female spline portion 50 provided on the inner peripheral surface of the base end portion (the left end portion in FIGS. 19 and 22) of the worm shaft 29 is provided at a distal end portion of the rotary shaft 32 of the electric motor 31.
- the ends of the two shafts 29 and 32 are connected to each other by a spline engaging portion 33 formed by spline engaging the spline portion 51. With this configuration, the worm shaft 29 rotates together with the rotation shaft 32.
- a bearing holder 149 is provided inside the gear housing 22a, and the worm shaft 19 is rotatably supported by the bearing holder 149.
- the large-diameter cylindrical portion 150 and the small-diameter cylindrical portion 151 are connected by a circular ring portion 152.
- This large diameter An outer ring 57 constituting the third ball bearing 36 is fitted and fixed inside the cylindrical portion 150.
- one axial end surface of the outer ring 57 (the right end surface in FIGS. 19 and 22) abuts against one surface (the left side surface in FIGS. 19 and 22) of the annular portion 152, and the axial direction of the outer ring 57 and the like.
- the end face (the left end face in FIGS.
- the inner ring 52 constituting the third ball bearing 36 is externally fitted and fixed to a portion of the worm shaft 29 near the base end near the base end, the portion coinciding with the spline engagement portion 33 in the axial direction. Further, one end surface in the axial direction of the inner ring 52 (the right end surface in FIGS. 19 and 22) abuts against the side surface of the flange 53 provided on the outer peripheral surface of the worm shaft 29 near the base end. The other end surface in the direction (the left end surface in FIGS. 19 and 22) is held down by a locking ring 155 which is locked to the inner peripheral surface of the base end of the worm shaft 29.
- a four-point contact type ball bearing is preferably used as the third ball bearing 36.
- the bearing holder 149 is supported on the inner side of the gear housing 22a to be able to freely swing.
- a pair of first through-holes are provided at two positions on the worm wheel 28 side (upper side in FIGS. 19 and 22) on the part opposite to the worm wheel 28 in a part of the small-diameter cylindrical portion 151 constituting the bearing holder 149.
- a hole 158 is formed. Then, as shown in FIG. 23, a swing shaft 159 is inserted inside the bearing holder 149 through each of the first through holes 158 while avoiding the worm shaft 29, and each of the first through holes is inserted.
- Portions near both ends of the swing shaft 159 are fitted in the holes 158 by gap fitting. Further, at both ends of the swing shaft 159, portions protruding from the respective first through holes 158 to the outside of the bearing holder 149 are formed in concave portions provided in the main body portion 135 constituting the gear housing 22a. 160 and the second through hole 161 are internally fitted by gap fitting, respectively.
- the wall portion 162 constituting the cover 136 of the gear housing 22a is superimposed on the outer peripheral surface of the portion of the main body portion 135 where the second through hole 161 is provided.
- the swing shaft 159 is prevented from falling out of the through hole 161.
- the bearing holder 149 is freely supported by the gear housing 22a for swing displacement about the swing shaft 159.
- each of the first through-holes 158 and one of the concave hole 160 and the second through-hole 161 is fastened to a portion near both ends of the swing shaft 159.
- the inner fitting can be fixed by fitting.
- the center axis o of the worm shaft 29 (Figs. 19, 20, 22) is viewed from above.
- This worm passes through a point Q (Figs. 19 and 22) on a straight line L parallel to the central axis o of the worm axis 29.
- An axis parallel to the center axis o of the wheel 28 (FIGS. 19 and 22) is set as the center axis of the swing axis 159.
- the tip of the worm shaft 29 (the right end in FIGS. 19 and 22) is rotatably supported by a fourth ball bearing 37 inside the gear housing 22a.
- the outer ring 60 constituting the fourth ball bearing 37 is fixed to a second bearing holder 164 fixed inside the gear housing 22a.
- the second bearing holder 164 has an L-shaped cross section and is formed in a ring shape.
- the outer ring is provided inside a cylindrical portion 165 provided on one side (the left side in FIGS. 19 and 22) of the second bearing holder 164. 60 is fixed inside.
- a substantially cylindrical bush 167 made of a resilient material is loosely fitted to a large-diameter portion 166 provided on the outer peripheral surface of a portion of the worm shaft 29 near the front end, which is provided outside the worm 27.
- the tip of the worm shaft 29 projects from one axial end surface of the bush 167 (the right end surface in FIGS. 19 and 22).
- An inner ring 65 constituting the fourth ball bearing 37 is externally fitted and fixed to an intermediate portion of the bush 167 in the axial direction.
- One end of the inner ring 65 in the axial direction (the left end in FIGS. 19 and 22) is connected to the other end in the axial direction of the bush 167 (the left end in FIGS. 19 and 22).
- the inner ring 65 is positioned in the axial direction.
- the worm shaft 29 can be inclined with respect to the bush 167 in a predetermined range (radial displacement). Is possible.
- a preload constituting the elasticity applying means 137 is provided between the other end surface of the second bearing holder 164 (the right end surface in FIGS. 19 and 22) and the bottom surface of the concave hole 72 provided in the gear housing 22a.
- a pad 142 is provided, and a small diameter portion 171 provided at the tip of the worm shaft 29 is inserted into a part of the preload pad 142 without play.
- the preload pad 142 is formed into a shape as if one of two outer circumferential portions of the outer peripheral surface of the cylinder were removed by injection molding a synthetic resin mixed with a solid lubricant. Building.
- the above preload A flat portion 172 and an arm portion 173 are provided at two positions radially opposite to the outer peripheral surface of the pad 142, and the half portion on the worm wheel 28 side (upper side in FIG. 24) and the worm wheel 28 respectively. It is provided on the opposite side (lower side in FIG. 24).
- the small-diameter portion 171 of the worm shaft 29 is inserted into a through hole 174 formed so as to penetrate the center of the preload pad 142 in the axial direction.
- the inner peripheral surface of the through hole 174 has a function as a sliding bearing that supports the small diameter portion 171.
- the inner peripheral surfaces of both ends of the through hole 174 are tapered surfaces whose diameter increases toward the opening end.
- Such a preload pad 142 supports the inside of the concave hole 72 provided in the gear housing 22a so as to be capable of being displaced within a predetermined range.
- the torsion coil spring 141 is provided around the preload pad 142. Then, a pair of locking portions 175 provided at two positions on the opposite side in the radial direction at both ends of the torsion coil spring 141 are pivoted to two positions on the other side in the radial direction on the other end surface of the second bearing holder 164. It is locked on one side of a pair of locking projections 176 provided so as to protrude in the direction. Further, the distal ends of the locking projections 176 are fitted in holes (not shown) provided at two positions on the bottom surface of the concave hole 72. With this configuration, the position of each of the locking projections 176 with respect to the gear housing 22a is regulated.
- the inner peripheral edge of the torsion coil spring 141 is elastically pressed against the first partial cylindrical surface portion 177 provided on the outer peripheral surface of the preload pad 142 on the side opposite to the foam wheel 28, whereby the worm shaft is formed.
- An elastic force in the direction toward the worm wheel 28 is applied to the tip of the worm wheel 29 via the preload pad 142.
- the center axis of the through hole 174 is aligned with the center axis of the second bearing holder 164. On the other hand, it is offset to one side (the upper side of Figs. 19, 20, 22, and 24). Therefore, when the distal end of the worm shaft 29 is inserted into the through hole 174 provided in the preload pad 142, the diameter of the torsion coil spring 141 is determined by the first cylindrical surface portion 177 provided in the preload pad 142. Are sexually spread.
- the torsion coil spring 141 tends to elastically return in the direction of unwinding (reducing the diameter), and the torsion coil spring 141 applies an elastic force in the direction of the directional force to the tip of the worm shaft 29 to the worm wheel 28. Is done.
- the second inner shaft 139 with the worm wheel 28 fitted and fixed to the outside is The distance between the worm shaft 29 and the center axes is elastically reduced. As a result, the tooth surfaces of the worm 27 of the shaft shaft 29 and the worm wheel 28 come into contact with each other in a state where a force preload is applied.
- the radius of curvature of the second partial cylindrical surface portion 178 provided on the worm wheel 28 side of the outer peripheral surface of the preload pad 142 is determined by the first partial cylindrical surface portion 177. Is smaller than the radius of curvature. Further, in a state where the torsion coil spring 141 is provided around the preload pad 142, the surface of the wire element for each one turn constituting the torsion coil spring 141 and another wire rod adjacent to each wire element are formed. An axial gap is provided between the surface of the element (between lines).
- the swing shaft 159 is inserted into and supported by the first and second through holes 158 and 161 and the concave hole 160 in a state where the swing shaft 159 is aligned. Also, in a state where the wall portion 162 constituting the cover 136 of the gear housing 22a is superimposed on a portion of the main body portion 135 where the second through hole 161 is provided, the main body portion 135 and the cover And 136 are connected by bolts or the like (not shown).
- the worm shaft is provided by the elasticity applying means 137 including the torsion coil spring 141 and the preload pad 142.
- the worm wheel 28 is provided with elasticity in the direction of the force at the tip of the worm wheel 28. For this reason, it is possible to apply a preload to the joint between the worm wheel 28 and the arm 27 of the worm shaft 29 with an inexpensive structure, and it is possible to suppress the generation of rattling noise at this joint.
- the oscillating shaft 159 which is the oscillating central axis of the worm shaft 29 in this embodiment, is the central axis of the worm shaft 29. Worm wheel above from above 28
- the worm wheel 28 is provided at a position shifted to the side in parallel with the central axis o of the worm wheel 28.
- the worm in the case of the present embodiment, the worm
- a bearing holder 149 supporting the third ball bearing 36 is swingably supported with respect to the gear housing 22a.
- the third ball bearing 36 a conventional one generally used without using a swing shaft fixed to a part of the outer ring is used. Can be supported with respect to the gear housing 22a so as to be capable of swinging displacement, thereby suppressing an increase in cost.
- the rocking shaft 159 is provided between the third ball bearing 36 and the joint portion between the worm 27 of the worm shaft 29 and the worm wheel 28. For this reason, it is possible to apply a large preload to the joint portion while reducing the swing displacement amount of the base end of the worm shaft 29 on the side of the electric motor 31, and to generate an unpleasant rattling sound at the joint portion. Can be suppressed more effectively.
- the rocking shaft is set on the opposite side of the electric motor 31 with respect to the joint. When the worm shaft 29 is provided, the swing displacement of the base end of the worm shaft 29 becomes large.
- the elasticity applying means 137 is provided on the opposite side of the swing shaft 159 with respect to the joint. Therefore, the amount of elastic deformation of the torsion coil spring 141 constituting the elasticity applying means 137 can be increased, and the amount of elasticity applied to the worm shaft 29 can be easily adjusted.
- the tip of the foam shaft 29 is provided inside the through hole 174 provided in the preload pad 142. ⁇ Easy to access.
- the contact portion The torsion coil spring 141 causes an inappropriate change in the elasticity applied to the worm shaft 29.
- an axial gap is provided between the surfaces of the above-mentioned one-turn wire element and the surface of another wire element adjacent to each wire element. Therefore, a predetermined elasticity can be applied to the worm shaft 29 more stably.
- FIGS. 25-26 show Embodiment 6 of the present invention.
- an outer peripheral surface near both ends of a swing shaft 159 for freely supporting the bearing holder 149 with respect to the gear housing 22a for swing displacement and each of the first Elastic rings 179 are provided between the inner peripheral surfaces of the through holes 158.
- an inner cylindrical portion 180 and an outer cylindrical portion 181 each made of a metal are concentrically connected to each other by a connecting portion 182 made of an elastic material made of rubber. That is, the connecting portions 182 are vulcanized and bonded to the cylindrical portions 180 and 181 to connect the cylindrical portions 180 and 181 together.
- the connecting portions 182 are provided at two positions on the opposite side in the radial direction of the portion between the cylindrical portions 180 and 181 and are separated from each other. Specifically, two positions at the end of the ⁇ Ohm wheel 28 (see FIGS. 19, 20, and 22) and the opposite side of this portion (two positions at both ends in the vertical direction in FIGS. 25 and 26) ) Are provided with the connecting portions 182, 182, and both ends in the axial direction of the worm shaft 29 are 90 degrees out of phase with the portion provided with the connecting portions 182 (both ends in front and back directions in FIG. 19, FIG. 20). The left and right ends of the space are defined as a space 183.
- each elastic ring 179 in the radial direction of the swing shaft 159 Force Differs in the circumferential direction. Further, the rigidity of each of the elastic rings 179 in the axial direction of the worm shaft 29 is reduced.
- the toothing at the joint between the worm 27 of the worm shaft 29 and the worm wheel 28 without increasing the rotation torque of the worm shaft 29 is performed.
- the generation of sound can be suppressed. That is, when the worm shaft 29 is supported with respect to the gear housing 22a so that the worm shaft 29 cannot be displaced in the axial direction, when the worm wheel 28 receives rotational vibration, the worm shaft 29 rotates. Easier to do. Since the worm shaft 29 is connected to the rotating shaft 32 of the electric motor 31 having a large moment of inertia (see FIGS. 19, 21, and 22), the worm shaft 29 is rotated based on the rotational vibration of the worm wheel 28.
- the force transmitted between the tooth surfaces can be reduced.
- each elastic ring 179 is varied in the circumferential direction, and the rigidity of each elastic ring 179 in the axial direction of the worm shaft 29 is reduced. Therefore, the worm shaft 29 can be easily displaced in the axial direction with respect to the gear housing 22a while securing the required rigidity of each of the elastic rings 179 as a whole. Therefore, the increase in the rotational torque of the worm shaft 29 can be more effectively suppressed.
- Other configurations and operations are the same as those of the fifth embodiment shown in FIGS. The same reference numerals are given to the same parts, and duplicate description is omitted.
- FIG. 27 shows a seventh embodiment of the present invention.
- the elastic ring 179 used in the sixth embodiment shown in FIG. 25 above is connected to the inner peripheral surface of the concave hole 160 and the second through hole 161 provided in the gear housing 22a. It is provided between the outer peripheral surfaces of both ends of the swing shaft 159.
- Other structures and operations are the same as in the sixth embodiment described above.
- an elastic material other than rubber, a synthetic resin, or the like other than rubber can be used as the elastic material constituting the connecting portion 182 of the elastic ring 179.
- the entire elastic ring 179 can be made of an elastic material such as a synthetic resin.
- FIGS. 28-29 show Embodiment 8 of the present invention.
- the coil spring 186 which is the elasticity applying means, is connected to the rotating shaft 32 of the electric motor 31 and the worm shaft 29 in the structure of the fifth embodiment shown in FIGS. It is provided between. That is, in the case of this embodiment, a concave portion 184 is provided on one end surface (the right end surface in FIG. 28) of the rotating shaft 32, and the bottom surface of the concave portion 184 and the base end surface of the worm shaft 29 (FIG. 28).
- the coil spring 186 is provided between the bottom surface of the spline hole 185 provided on the left end surface).
- the coil spring 186 gives the worm shaft 29 an elastic force in a direction away from the rotation shaft 32.
- the swing shaft 159 serving as the swing center of the worm shaft 29 is moved from the center axis ol of the worm shaft 29 to the worm wheel 2. It is provided at a position shifted to the 8 side (upper side in FIG. 28). With this configuration, the worm shaft 29 is elastically displaced toward the worm wheel 28 around the oscillation shaft 159.
- the outer peripheral surface of the distal end of the worm shaft 29 is a single cylindrical surface that is not stepped, and the distal end is formed by a concave hole 72 provided in the gear housing 22a. It is located inside.
- An elastic ring 187 corresponding to a second elastic ring and a fourth ball bearing 37 are provided between the inner peripheral surface of the concave hole 72 and the outer peripheral surface of the tip of the worm shaft 29. .
- the fourth ball bearing 37 is provided around the tip of the worm shaft 29 by fixing the inner ring 65 to the tip of the worm shaft 29.
- the elastic ring 187 includes an inner cylindrical portion 188 and an outer cylindrical portion 189, each of which is made of metal, formed of an elastic material such as an elastomer such as rubber. They are concentrically connected to each other by a connecting portion 190 made of stainless steel.
- Each of the connecting portions 190 is provided at two positions on the radially opposite side of the portion between the cylindrical portions 188 and 189 in a state of being separated from each other. Specifically, only two positions at both ends in the direction (in the horizontal direction in FIG. 29) in which the phase differs by 90 degrees with respect to the oscillating displacement direction of the worm shaft 29 (the vertical direction in FIG. 29).
- Each of the connecting portions 190 is provided. With this configuration, the rigidity of the elastic ring 187 becomes lower in the direction of the oscillating displacement of the worm shaft 29 and becomes higher in the direction different from the direction of the oscillating displacement by 90 degrees.
- the outer diameter of the worm shaft 29 located at both ends in the swing displacement direction of the worm shaft 29 is located between the inner diameter side and the outer diameter side cylindrical portions 188 and 189.
- stopper portions 191 made of an elastic material such as rubber or the like and having a partially arc-shaped cross section are provided at two positions on the inner peripheral surface of the side cylindrical portion 189.
- a minute gap is provided between the inner peripheral surface of each of the stopper portions 191 and the outer peripheral surface of the inner cylindrical portion 188.
- Such an elastic ring 187 fixes the inner diameter side cylindrical portion 188 to the outer ring 60 constituting the fourth ball bearing 37 and fixes the outer diameter to the concave hole 72 provided in the gear housing 22a.
- the side cylindrical portion 189 is provided between the worm shaft 29 and the gear housing 22a by being fitted and fixed inside.
- the rigidity of the elastic ring 187 provided between the fourth ball bearing 37 and the gear housing 22a is low with respect to the swing displacement direction of the worm shaft 29.
- the swing displacement direction and the direction in which the phase is different by 90 degrees are increased. For this reason, while preventing the worm shaft 29 from being displaced in an unintended direction, the swing displacement of the worm shaft 29 toward the ohm wheel 28 can be more easily performed, and the toothing at the joint portion can be facilitated. The generation of sound can be suppressed more effectively.
- the elastic ring 187 is provided with the stopper 191 for restricting the oscillating displacement of the worm shaft 29, so that the worm shaft 29 swings excessively. Dislocation can be prevented.
- Other configurations and operations are the same as those of the fifth embodiment shown in FIGS. 18 to 24 described above, and therefore, the same reference numerals are given to the same parts, and duplicate description will be omitted.
- FIG. 30 shows a ninth embodiment of the present invention.
- the coil spring 186 as the elasticity applying means is provided between the bearing holder 149 and the gear housing 22a in the structure of the embodiment 8 shown in FIG. That is, in the case of the present embodiment, the coil spring 186 is provided between the inner surface of the gear housing 22a and the bottom of the concave hole 192 provided on the outer peripheral surface of the large-diameter cylindrical portion 150 constituting the bearing holder 149. Is provided.
- the coil spring 186 imparts radial elasticity to the base end of the worm shaft 29.
- the coil spring 186 is provided at a position shifted in the axial direction of the worm shaft 29 toward the base end side of the worm shaft 29 with respect to the swing shaft 159 serving as the swing center of the worm shaft 29. .
- the worm shaft 29 is oscillatingly displaced around the oscillating shaft 159 toward the worm wheel 28 side.
- a preload can be applied to the joint portion without increasing the total length of a portion formed by connecting the worm shaft 29 and the rotating shaft 32 of the electric motor 31. That Other configurations and operations are the same as those of the eighth embodiment shown in FIGS. 28 to 29 described above, and therefore, the same parts are denoted by the same reference numerals and overlapping description will be omitted.
- FIG. 31 shows a tenth embodiment of the present invention.
- the overall length of the small-diameter cylindrical portion 151a constituting the bearing holder 149a is increased, and a through-hole is formed in a part of the small-diameter cylindrical portion 151a in the circumferential direction at an intermediate portion in the axial direction.
- the worm shaft 29 is provided inside the bearing holder 149a, and between the outer peripheral surface of the base end portion of the worm shaft 29 and the inner peripheral surface of the large-diameter cylindrical portion 150 constituting the bearing holder 149a.
- Third and fourth ball bearings 36 and 37 are provided between the outer peripheral surface of the distal end portion of the worm shaft 29 and the inner peripheral surface of the distal end portion of the small-diameter cylindrical portion 151a.
- an elastic ring 194 (elastic material) made of an elastic material such as rubber is provided between the outer peripheral surface of the distal end portion of the small-diameter cylindrical portion 151a and the inner peripheral surface of the concave hole 72 provided in the gear housing 22a. (Equivalent to).
- a part of the worm 27 of the worm shaft 29, which is exposed outside the small-diameter cylindrical portion 151a from the through hole 193 provided in the small-diameter cylindrical portion 151a is combined with the worm wheel 28.
- toothing at the joint between the worm 27 of the worm shaft 29 and the worm wheel 28 is performed. It is possible to prevent the generation of abnormal noise due to the collision between the tip of the worm shaft 29 and the fourth ball bearing 37, which does not impair the sound generation suppressing effect. Position can be prevented.
- Other configurations and operations are the same as those in the embodiment 8 shown in FIG. 2829 described above, and therefore, the same reference numerals are given to the same parts, and the duplicate description will be omitted.
- FIG. 32 shows Example 11 of the present invention.
- the inner and outer surfaces of the gear housing 22a are attached to a part of the gear housing 22a facing the distal end surface of the worm shaft 29. Forming through-hole 195 to penetrate are doing.
- a bottomed cylindrical cap 196 made of an elastic material such as rubber or synthetic resin is fixed in the through hole 195.
- the distal end portion of the small-diameter cylindrical portion 151a constituting the bearing holder 149a is internally fitted to and supported by a projection 198 provided on the inner peripheral surface of the distal end portion of the cylindrical portion 197 constituting the cap 196.
- the cap 196 corresponds to an elastic material.
- Other configurations and operations are the same as those of the tenth embodiment shown in FIG. 31 described above, and thus, duplicated description will be omitted.
- FIGS. 33-34 show a twelfth embodiment of the present invention.
- a plate portion 199 for closing the distal end opening of the small-diameter cylindrical portion 151a of the bearing holder 149a is provided in the structure of the tenth embodiment shown in FIG.
- the shaft is provided with a shaft 200 protruding in the axial direction.
- An elastic ring 201 corresponding to a second elastic ring is provided between the outer peripheral surface of the shaft portion 200 and the inner peripheral surface of the concave hole 72 provided in the gear housing 22a.
- the elastic ring 201 connects an outer diameter side cylindrical portion 202 and an inner diameter side cylindrical portion 203, each of which is made of metal, to a connecting portion made of an elastic material such as rubber. They are concentrically connected by 204. Also, one half of the outer cylindrical portion 202 in the axial direction (the left half of FIG. 33) is made to protrude in the axial direction from one end surface of the inner cylindrical portion 203 in the axial direction (the left end surface of FIG. 33). Thus, the entire length of the outer diameter side cylindrical portion 202 is made larger than the entire length of the inner diameter side cylindrical portion 203.
- An axially protruding portion 205 is provided on the outer peripheral edge of one end surface in the axial direction (the left end surface in FIG. 33) of the connecting portion 204, and this protruding portion 205 is attached to the shaft of the outer cylindrical portion 202. The direction half is connected to the inner peripheral surface.
- a part of the connecting portion 204 penetrates axially at two positions on opposite sides in the radial direction, which are located at both ends of the worm shaft 29 in the swinging displacement direction (vertical direction in Figs. 16 and 17).
- a through hole 206 is provided.
- the cylindrical portion 203 is externally fitted and fixed to provide between the gear housing 22a and the shaft portion 200.
- the connecting portion 204 The outer peripheral surface of the leading end of the small-diameter cylindrical portion 151a constituting the bearing holder 149a is opposed to the inner peripheral surface of the provided protrusion 205 via a minute gap.
- the projection 205 corresponds to a stopper for restricting the swing displacement of the worm shaft 29.
- a portion of the elastic ring 201 having low rigidity and the projection 205 serving as a stopper for preventing the worm shaft 29 from swinging excessively are combined with the above-mentioned portion.
- the elastic ring 201 is shifted in the axial direction.
- Other configurations and operations are the same as those of the tenth embodiment shown in FIG. 31 described above, and therefore, the same reference numerals are given to the same parts, and duplicate description will be omitted.
- FIG. 35 shows a thirteenth embodiment of the present invention.
- the structure is such that the structure of Embodiment 9 shown in FIG. 30 described above is combined with the structure of Embodiment 10 shown in FIG. 31 described above. That is, in the case of the present embodiment, a bearing holder 149a that supports the third ball bearing 36 and the fourth ball bearing 37 (see FIG. 31) with the structure of the tenth embodiment shown in FIG.
- a coil spring 186 is provided in the radial direction of the bearing holder 149a between the outer peripheral surface of the large-diameter cylindrical portion 150 and the inner surface of the gear housing 22a.
- the other configurations and operations are the same as those of the ninth embodiment shown in FIG. 30 and the tenth embodiment shown in FIG. 31 described above. Is omitted.
- FIGS. 36-37 show Embodiment 14 of the present invention.
- one end of the rotating shaft 32a of the electric motor 31 (the right end in FIG. 36) and the base end of the worm shaft 29a have the same structure as that of the tenth embodiment shown in FIG. (The left end in FIG. 36) is connected to each other via a coupling ring 207 made of an elastic material in a state where relative rotation between them is prevented.
- the coupling ring 207 is made of an elastic material such as rubber or the like and is formed in a cylindrical shape at a plurality of locations at equal intervals in the circumferential direction (eight locations in the illustrated example). ),
- a through hole 208 having a substantially triangular cross section is formed to penetrate in the axial direction.
- the circumferential direction of the portion near the outer diameter of the base end surface (the left end surface in FIG. 36) of the worm shaft 29a and the portion near the outer diameter of the one end surface (the right end surface in FIG. 36) of the rotating shaft 32a is aligned with every other through hole 208 provided in the coupling ring 207
- Protrusions 209a and 209b projecting in the axial direction are provided at the positions. Each of these projections 209a and 209b can be freely fitted inside each through hole 208 provided in the coupling ring 207 without rattling.
- the projections 209a provided on the worm shaft 29a and the projections 209b provided on the rotary shaft 32a are alternately arranged in the circumferential direction from both axial sides of the coupling ring 207 to the respective through holes 208.
- the worm shaft 29a and the rotating shaft 49a are connected via the coupling ring 207 by being fitted inside without rattling.
- a coil spring 186 is provided between the bottom surface of the concave hole 210 provided at the center of the base end surface of the worm shaft 29a and the center of one end surface of the rotary shaft 32a.
- the worm shaft 29a is provided with elasticity in a direction away from the rotation shaft 32a.
- the worm shaft 29a and the rotation shaft 32a are connected to each other via the coupling ring 207. Therefore, rotational vibration can be transmitted between the rotating shaft 32a and the worm shaft 29a.
- Other configurations and operations are the same as those of the tenth embodiment shown in FIG. 31 described above, and therefore, the same reference numerals are given to the same parts, and duplicate description will be omitted.
- a plurality of first holes are provided instead of the respective through holes 208 at the formation positions of the respective through holes 208 provided in the coupling ring 207.
- the second concave portions may be provided alternately in the circumferential direction. In this case, the bottom of each of the first and second concave portions is on the opposite side in the axial direction of the coupling ring 207.
- the respective protrusions 209a provided on the base end surface of the worm shaft 29a and the respective protrusions 209b provided on one end surface of the rotary shaft 32a are respectively fitted in the respective first and second recesses.
- the diametric shaft 29 a and the rotating shaft 32 a are connected via the coupling ring 207.
- Grease may be filled between the bearing holders 149, 149a supporting the 36 (or 37) and the gear housing 22a.
- a reaction applied to the worm shafts 29 and 29a from the worm wheel 28 is performed.
- the bearing holders 149 and 149a are displaced by swinging. ⁇ I can do it.
- the bearing holders 149 and 149a supporting the 36 (or 37) may be made of a magnesium alloy.
- the vibration generated on the worm shafts 29 and 29a due to the abutment between the tooth surfaces of the worm 20 and the worm wheel 28 of the worm shafts 29 and 29a is reduced by the bearing holder. Since the vibration can be easily absorbed by 149 and 149a, the vibration can be transmitted to the gear housing 22a.
- the pinion 11 fixed to the end of the pinion shaft 10 (see Figs. 5 and 46) and the rack 10 (see Fig. 46) are directly connected. It is not limited to such a structure.
- a pin provided at the lower end of the pinion shaft is engaged in a long hole of a pinion gear provided separately from the pinion shaft so that displacement in the longitudinal direction of the long hole can be freely adjusted.
- VCS vehicle speed responsive variable gear ratio mechanism
- the present invention is not limited to the structure in which the electric motor 31 is provided around the steering shaft 2.
- an electric motor 31 may be provided around the pinion 11 (see FIGS. 5 and 46) to be combined with the rack 12.
- a worm wheel constituting the worm reducer 16a is fixed to the pinion 11 or a part of a member supported by the pinion 11.
- the torque sensor 3 (see FIG. 46) can be provided at the periphery of the pinion 11 separated from the periphery of the steering shaft 2.
- the present invention can also be implemented with such a structure shown in FIG. [0193] Further, as shown in Fig.
- an electric motor 31 may be provided on a part of the rack 12 and around the sub-pinion 211, which is coupled to a position disengaged from the engagement part with the pinion 11. it can.
- the worm wheel fixed to the sub-pinion 211 and the worm shaft 29 (29a) are combined.
- the torque sensor 3 can be provided around the pinion 11.
- the vibration transmitted from the ground to the pinion 11 via the wheels is prevented from being transmitted to the steering wheel 1 at the intermediate portion of the intermediate shaft 8.
- Buffer device 212 is provided.
- the shock absorbing device 212 is configured by combining an inner shaft and an outer shaft in a telescope shape, and connecting an elastic material between end peripheral surfaces of both shafts. The present invention can be implemented with such a structure shown in FIG.
- Figs. 40 to 45 show Embodiment 15 of the present invention.
- the electric power steering apparatus includes a steering shaft 2 (see FIGS. 1 and 46) as an assist shaft having a steering wheel 1 (see FIGS. 1 and 46) fixed to a rear end thereof, and a steering wheel 1 (see FIGS. 1 and 46).
- a steering column 15 (see FIGS. 1, 46, etc.) through which the shaft 2 can pass, a worm reducer 16b for providing an auxiliary tonolek to the steering shaft 2, and a pinion 11 provided at the front end of the steering shaft 2 (See Fig. 46), the rack 12 combined with the pinion 11 or a member supported by the pinion 11 (see Fig. 46), the torque sensor 3 (see Fig. 46), the electric motor 31, and the controller. 6 (see FIG. 46).
- the worm speed reducer 16b includes a worm wheel 28 that can be externally fixed to a part of an inner shaft 18 (see FIG. 1 and the like) constituting the steering shaft 2, a worm shaft 29, and a torsion coil spring 30a. , And a preload pad 213a.
- the torque sensor 3 is provided around an intermediate portion of the steering shaft 2, and detects the direction and magnitude of the tonnolek applied to the steering shaft 2 from the steering wheel 1, and detects the detected value. Is sent to the controller 6. Then, in response to the detection signal, the controller 6 sends a drive signal to the electric motor 31 to generate an auxiliary tonnole with a predetermined size in a predetermined direction.
- the worm wheel 28 and the worm shaft 29 are provided inside the gear housing 22, and the worm wheel 28 and the worm 27 provided at an intermediate portion of the worm shaft 29 are combined. Further, a female spline portion 50 provided on the inner peripheral surface of the base end portion (left end portion in FIG.
- the base end of the worm shaft 29 is rotatably supported inside the gear housing 22 by a third ball bearing 36, which is a first bearing. Further, the inner ring 52 constituting the third ball bearing 36 is externally fitted to a portion of the outer peripheral surface near the base end of the worm shaft 29 which coincides with the spline engaging portion 33 in the axial direction. Then, the axial center position of the spline engagement portion 33 and the axial center position of the third ball bearing 36 are substantially matched. Further, by providing a minute gap between the inner peripheral surface of the inner ring 52 and the outer peripheral surface of the worm shaft 29, the inclination of the worm shaft 29 with respect to the third ball bearing 36 in a predetermined range is enabled. I have.
- the inner ring 52 is screwed and fixed to both axial end surfaces of the inner ring 52, the side surface of a flange 53 provided on the outer peripheral surface of the worm shaft 29 near the base end, and the male screw portion 54 provided at the base end of the worm shaft 29.
- the elastic rings 215 are provided between the nuts 55 and the side surfaces of the flange 214 provided on the outer peripheral surface of the nut 55.
- the inner ring 52 is elastically held between the side surfaces of the flanges 53 and 214.
- the worm shaft 29 is supported by the third ball bearing 36 so as to be capable of elastic displacement within a predetermined range in the axial direction.
- a four-point contact type ball bearing is used as the third ball bearing 36.
- the tip of the worm shaft 29 (the right end in FIGS. 40 and 41) is rotatably supported inside the gear housing 22 by a fourth ball bearing 37 as a second bearing.
- a bearing holder 216 which is a buffer member, is fitted and fixed in the concave hole 72 provided in the gear housing 22.
- the bearing holder 216 is formed by integrally combining a pair of bearing holder elements 217 each made of a synthetic resin, and has a large-diameter cylindrical portion 218 and a small-diameter cylindrical portion 219. And concentric with each other Tied together.
- a pair of plane portions 234 (FIG.
- the inner surface of the large-diameter cylindrical portion 218 at the end opposite to the small-diameter cylindrical portion 219 includes the flat portions 234 and 234.
- a pair of inward flange portions 220a and 220b are formed at positions different in phase by 90 degrees from each other so as to protrude toward the inner diameter side. The distance between the inner surfaces of the inward flange portions 220a and 220b and the inner surface of the small-diameter cylindrical portion 219 (the left side surface in FIGS.
- the large-diameter cylindrical portion 218 deviated from each flat portion 234 is slightly larger than the outer diameter of the outer ring 60.
- the distance d between the flat portions 234 is substantially equal to the outer diameter of the outer ring 60.
- the axial displacement of the outer ring 60 is prevented in a state where the outer ring 60 is internally fitted to and supported by the outer ring 18, while the radial direction of the outer ring 60 is limited only in the direction along each of the flat portions 234 (the outer ring 60 Displacement within a predetermined range (until the outer peripheral surface abuts the inner peripheral surface of the large-diameter cylindrical portion 218) becomes possible. That is, the displacement of the outer ring 60 in the left and right directions in FIGS. 43 and 44 is prevented. Further, a locking groove 221 is formed over the entire circumference at an axially intermediate portion of the outer peripheral surface of the large diameter cylindrical portion 218. I have.
- Such a bearing holder 216 has such a shape as to be obtained by dividing the bearing holder 216 into two parts by an imaginary plane including the central axis. Consisting of
- a flat plate portion 233 parallel to each of the flat portions 234 is provided at a circumferential central portion of the semi-cylindrical portion 223 provided on each of the bearing holder elements 217 for forming the small diameter cylindrical portion 219. ing. Then, cutouts 222a and 222b (FIGS. 42, 44 and 45) penetrating in the radial direction are formed in the middle part of each of the flat plate portions 233 in such a manner that one end thereof opens to the end face of each of the flat plate portions 233. are doing.
- the notches 222a and 222b are used to lock both ends of the torsion coil spring 30a described later, and have different shapes as shown in FIGS. 45 (a) and 45 (b).
- these notches 222a and 222b have different lengths from the front end face to the rear end of each flat plate portion 233. Further, a bent portion 235 is formed at the inner end of each of the cutouts 222a and 222b so that the cutouts 222a and 222b are bent in the same direction.
- a preload pad 213a is arranged inside the small-diameter cylindrical portion 219 constituting the bearing holder 216. As shown in detail in FIG. 43, the preload pad 213a is formed in a substantially cylindrical shape by, for example, injection molding a synthetic resin mixed with a solid lubricant. The preload pad 213a is engaged with the outer peripheral surfaces of both ends of the preload pad 213a. The protrusions 230 are formed so as to protrude toward the outer diameter over the entire circumference. A small-diameter portion 68 provided near the tip of the worm shaft 29 is freely inserted into the through hole 231 provided in the center of the preload pad 213a so as to penetrate in the axial direction. I have.
- the inner peripheral surface of the through hole 231 has a function as a sliding bearing for supporting the small diameter portion 68.
- a tapered surface 232 whose diameter increases toward the opening end is provided on the inner peripheral surface of the base end of the worm shaft 29.
- the preload pad 213a constitutes the bearing holder 216. It is located inside the small diameter cylindrical part 219.
- the distance d between the inner peripheral surface of the small-diameter cylindrical portion 219 and the portion facing each flat plate portion 233 is slightly larger than the outer diameter of each locking projection 230 provided on the preload pad 213a. .
- the preload pad 213a can be displaced inside the small-diameter cylindrical portion 219 until the outer peripheral edge of each of the locking projections 230 hits the inner peripheral surface of the small-diameter cylindrical portion 219. ing.
- a pair of locking portions 73a provided in a state of being bent toward the outer diameter side at two positions on the opposite side in the radial direction at both ends of the torsion coil spring 30a are combined with the flat plate portion 233 constituting the small diameter cylindrical portion 219. Formed into It is locked in a pair of notches 222a and 222b.
- the center position of the main body of the torsion coil spring 30a is positioned at one end in the circumferential direction of each of the bearing holder elements 217 (see FIG. 40-44).
- the bent portion 235 provided in each of the notches 222a and 222b has a function of preventing the locking portions 73a and 73b from falling off from the notches 222a and 222b.
- the bearing holder 216 is provided on the gear housing 22. It is fitted and fixed in the recess 72 (FIGS. 40 and 41). That is, the large-diameter cylindrical portion 218 of the bearing holder 216 is internally fixed to the large-diameter cylindrical portion 226 on the opening end side forming the concave hole 72, and the large-diameter cylindrical portion 226 of the concave hole 72 is fixed.
- the elastic ring 224 is elastically compressed between the inner peripheral surface and the bottom surface of the locking groove 221.
- a substantially annular gap 228 is formed between the inner peripheral surface of the small-diameter cylindrical portion 227 on the bottom surface constituting the concave hole 72 and the outer peripheral surface of the small-diameter cylindrical portion 219 of the bearing holder 216. .
- the outer peripheral surface and part of both axial side surfaces of the fourth ball bearing 37 are covered by the bearing holder 216, and the axial displacement of the fourth ball bearing 37 with respect to the bearing holder 216 is performed. Is prevented, and displacement in a predetermined range along each flat surface portion 234 in the radial direction of the fourth ball bearing 37 with respect to the bearing holder 216 is allowed.
- the inside of the bush 225 fitted inside the fourth ball bearing 37 supported via the bearing holder 216 in the gear housing 22 is provided at the tip of the worm shaft 29.
- the large diameter portion 63 is loosely inserted.
- the large diameter portion 63 can be displaced in the axial direction with respect to the bush 225.
- the small diameter portion 68 provided at the tip of the worm shaft 29 is inserted into the through hole 231 provided in the preload pad 213a without play.
- the distal end of the worm shaft 29 is provided with an opposing force and a directional elastic force to the worm wheel 28 from the torsion coil spring 30a via the preload pad 213a.
- the center axis of the through hole 231 is aligned with the center axis of the bearing honoreda 216 and the concave hole 72. On the other hand, it is offset to one side (the upper side in Fig. 4042). And in this through hole 231 With the insertion of the tip of the worm shaft 29 on the side, the diameter of the torsion coil spring 30a is elastically expanded by the outer peripheral surface of the preload pad 213a.
- the torsion coil spring 30a tends to resiliently return in the direction of unwinding (reducing the diameter), and from the torsion coil spring 30a to the tip of the worm shaft 29 via the preload pad 213a.
- the worm wheel 28 is provided with elasticity in the direction of the directional force. With this configuration, the distance between the center axes of the inner shaft 18 to which the worm wheel 28 is externally fixed and the worm shaft 29 is reduced in nature. As a result, the tooth surfaces of the worm 27 of the worm shaft 29 and the worm wheel 28 come into contact with each other in a state where a force preload is applied.
- the surface direction of the abutting surfaces at both ends in the circumferential direction of the bearing holder elements 217 constituting the bearing holder 216 (the surface direction parallel to the paper surface of Figs. 40 and 41). This is made to coincide with the direction in which the worm shaft 29 is given elasticity by the torsion coil spring 30a.
- a circumferential gap may be formed between the both end surfaces without abutting the circumferential end surfaces of the bearing holder elements 217.
- it is preferable that a virtual plane passing through the gap is made to coincide with the direction in which the elasticity is applied.
- the preload pad 213a is attached to the tip of the worm shaft 29 by the torsion coil spring 30a.
- the elasticity of the worm wheel 28 in the direction of the directional force is given through the worm wheel 28. Therefore, with an inexpensive structure, it is possible to apply a preload to the joint between the worm wheel 28 and the worm 27 of the worm shaft 29, and it is possible to suppress the generation of rattling noise at this joint.
- the preload applied to the joint portion can be easily maintained stably within a limited narrow range regardless of the axial force applied from the worm wheel 28 to the worm shaft 29. . For this reason, generation of rattling noise in this joint can be effectively suppressed.
- the preload pad 213a for applying elasticity to the worm shaft 29 and the fourth ball bearing 37 for supporting the tip of the worm shaft 29 The axial displacement of the worm shaft 29 is allowed. Therefore, when a large axial reaction force is applied to the worm shaft 29 from the worm wheel 28 when the electric motor 31 is driven. However, the preload pad 213a and the fourth ball bearing 37 are not strongly pressed against another member in the axial direction of the worm shaft 29 by the reaction force.
- the preload applied to the joint portion between the worm wheel 28 and the worm 27 of the worm shaft 29 is equal to the above-described counter pressure. It is possible to prevent large fluctuations due to the influence of force. As a result, this preload can be easily and stably maintained in a limited narrow range for a long period of time, and generation of rattling noise at the joint can be effectively suppressed.
- the bearing holder 216 for regulating the displacement of the fourth ball bearing 37 is made of a synthetic resin, the frictional force acting between the fourth ball bearing 37 and the bearing holder 216 is reduced. As a result, the fourth ball bearing 37 can be easily displaced in the radial direction. For this reason, the generation of rattling noise in the joint can be more effectively suppressed. Further, the outer peripheral surface and part of both axial side surfaces of the fourth ball bearing 37 are covered with the bearing holder 216 to restrict the axial displacement of the fourth ball bearing 37 with respect to the bearing holder 216. are doing. For this reason, it is possible to easily suppress the rattle of the fourth ball bearing 37 without pressing the worm shaft 29 against the fourth ball bearing 37 in the axial direction.
- the axial displacement of the fourth ball bearing 37 with respect to the bearing holder 216 is prevented, and the radial direction of the fourth ball bearing 37 with respect to the bearing holder 216 is prevented.
- the outer peripheral surface of the worm shaft 29 and the fourth ball bearing 37 are displaced. Sliding friction between the bearing 37 and the inner peripheral surface of the inner ring 65 can be easily reduced, and the swing displacement can be easily performed. As a result, it is possible to reduce the friction loss as a whole and easily apply an appropriate preload to the joint.
- the flexible ring 224 is provided between the bearing holder 216 and the gear housing 22, the play of the bearing holder 216 with respect to the gear housing 22 is reduced. It can be easily suppressed. For this reason, dimensional control of each part can be easily performed, and the engagement at the joint part can be easily maintained in an appropriate state.
- the elastic ring 224 is formed between the inner peripheral surface of the concave hole 72 of the gear housing 22 and the bottom surface of the locking groove 221 of the bearing holder 216. ⁇ sexual Can be compressed. Therefore, the work of assembling the bearing holder 216 can be performed while preventing the internal force of the recess 72 from falling off of the bearing holder 216, and the work of assembling the bearing holder 216 can be easily performed.
- a pair of bearing holder elements 217 having a shape obtained by dividing bearing bearing 216 into two parts by an imaginary plane including the central axis of bearing holder 216. It consists of. Therefore, the operation of forming each bearing holder element 217 for obtaining the bearing holder 216 can be facilitated, and the operation of assembling the fourth ball bearing 37 inside the bearing holder 216 can be performed more easily. Further, the surface direction of the abutting surfaces at both ends in the circumferential direction of each bearing holder element 217 is made to coincide with the direction in which the worm shaft 29 is given elasticity by the torsion coil spring 30a. Therefore, when the worm shaft 29 swings and displaces, the radial displacement of the fourth ball bearing 37 is hindered by the bearing holder 216, and the swing displacement of the worm shaft 29 becomes easier. it can.
- locking projections 230 protruding outward are provided on the outer peripheral surfaces of both ends in the axial direction of the preload pad 213a. Therefore, the torsion coil spring 30a can be prevented from falling off from the outer peripheral surface of the preload pad 213, and the displacement of the torsion coil spring 30a in the axial direction of the preload pad 213 can be restricted.
- Other configurations and operations are the same as those of the first embodiment shown in FIG. 119, and therefore, the same parts are denoted by the same reference numerals and overlapping description and illustration are omitted.
- the bearing holder 216 is formed by a single member which is not formed by abutting the bearing holder element 217 which is a separate member.
- a single member may be provided with a cutout in a part of the circumferential direction over the entire length in the axial direction.
- the diameter of the bearing holder 216 can be elastically greatly increased, and the fourth ball bearing 37 is provided inside the bearing holder 216 in the axial direction of the fourth ball bearing 37.
- the work of assembling in such a way as to regulate the displacement of can be performed easily. Further, the bearing holder 216 can easily absorb dimensional errors and assembly errors of components provided around the bearing holder 216.
- the notch provided in the bearing holder 216 can absorb the dimensional change, and the dimensional change of the bearing holder 216 other than the notch can be suppressed.
- An elastic member may be provided between the bearing holder 216 and the fourth ball bearing 37.
- the play of the fourth ball bearing 37 with respect to the bearing holder 216 can be easily suppressed.
- dimensional control of each part can be easily performed, and the engagement at the joint part can be easily maintained in an appropriate state.
- the operation of assembling the fourth ball bearing 37 to the bearing holder 216 can be performed while compressing the elastic member between the bearing holder 216 and the fourth ball bearing 37. Therefore, during the above operation, the fourth ball bearing 37 can be prevented from dropping out of the bearing holder 216, and the operation of assembling the fourth ball bearing 37 can be easily performed.
- the present invention is not limited to the structure in which the electric motor is provided around the steering shaft 2.
- the present invention can be implemented with a structure in which an electric motor 31 is provided around a pinion 11 (see FIG. 44) to be combined with a rack 12.
- a worm wheel constituting the worm speed reducer 16 is fixed to the pinion 11 or a part of a member supported by the pinion 11.
- the torque sensor 3 can be provided around the pinion 11 but not around the steering shaft 2.
- the electric motor 31 is provided on a part of the rack 12 around the sub-pinion 75, which is coupled to a position disengaged from the engagement part with the pinion 11.
- the present invention can also be implemented with a modified structure.
- the worm wheel 29 fixed to the sub-pinion 75 and the worm shaft 29 are combined.
- the torque sensor 3 (see FIG. 44) is installed around the pinion 11. You can go.
- the vibration transmitted from the ground to the pinion 11 via the wheels is prevented from being transmitted to the steering wheel 1 at the intermediate portion of the intermediate shaft 8.
- a shock absorber 76 is provided.
- the shock absorber 76 is configured by combining an inner shaft and an outer shaft in a telescope shape, and connecting an elastic material between end peripheral surfaces of both shafts.
- the assist shaft of the present invention can be any member of the steering shaft, the pinion, and the sub-pinion that fits with the rack at a position away from the pinion.
- a rotor phase detector for switching the direction of the exciting current sent to the coil 45, which constitutes the electric motor 31, is composed of a brush 48 and a commutator 46 (see FIGS. 2 and 3). It is not limited to the case where it is completed.
- the rotor phase detector is constituted by an encoder 78 made of a permanent magnet fixed to the rotating shaft 32 and a Hall IC 77, and the electric motor 31 has a so-called brushless structure. It can also be. Further, in the case of the structure shown in FIG.
- the stator 39a includes a core 82 made of a laminated steel plate fixed to the inner peripheral surface of the case 23, and a coil 83 wound around a plurality of portions of the core 82.
- the rotor 38a is constituted by a permanent magnet 84 fixed to the outer peripheral surface of the intermediate portion of the rotating shaft 32.
- the worm speed reducer of the present invention is not limited to those used for such purposes, but is not limited to an electric bed, an electric table, an electric chair, and an electric linear actuator incorporated in various mechanical devices such as lifters. It can also be used by incorporating it into a computer.
- the output of the electric motor is decelerated by the worm speed reducer, taken out to the rotating shaft, and the output shaft provided around the rotating shaft. Is expanded and contracted via a ball screw or the like.
- the present invention can be applied to a worm speed reducer incorporated in such an electric linear actuator.
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Power Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Power Steering Mechanism (AREA)
- Gear Transmission (AREA)
- General Details Of Gearings (AREA)
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP04746356A EP1637769A1 (en) | 2003-06-25 | 2004-06-24 | Worm speed reducer and electric power steering device |
US10/540,625 US7360467B2 (en) | 2003-06-25 | 2004-06-24 | Worm reduction gear and electric power steering apparatus |
US11/798,166 US7455149B2 (en) | 2003-06-25 | 2007-05-10 | Worm reduction gear and electric power steering apparatus |
US11/798,164 US7455148B2 (en) | 2003-06-25 | 2007-05-10 | Worm reduction gear and electric power steering apparatus |
Applications Claiming Priority (6)
Application Number | Priority Date | Filing Date | Title |
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JP2003180959 | 2003-06-25 | ||
JP2003-180959 | 2003-06-25 | ||
JP2003271418 | 2003-07-07 | ||
JP2003-271418 | 2003-07-07 | ||
JP2004-181600 | 2004-06-18 | ||
JP2004181600A JP4716679B2 (ja) | 2003-06-25 | 2004-06-18 | ウォーム減速機及び電動式パワーステアリング装置 |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/540,625 Continuation US7360467B2 (en) | 2003-06-25 | 2004-06-24 | Worm reduction gear and electric power steering apparatus |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2005001309A1 true WO2005001309A1 (ja) | 2005-01-06 |
Family
ID=33556152
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/JP2004/008887 WO2005001309A1 (ja) | 2003-06-25 | 2004-06-24 | ウォーム減速機及び電動式パワーステアリング装置 |
Country Status (4)
Country | Link |
---|---|
US (3) | US7360467B2 (ja) |
EP (1) | EP1637769A1 (ja) |
JP (1) | JP4716679B2 (ja) |
WO (1) | WO2005001309A1 (ja) |
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Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7665571B2 (en) * | 2005-02-28 | 2010-02-23 | Honda Motor Co., Ltd. | Power steering system in low floor type small vehicle |
JP2009502613A (ja) * | 2005-07-27 | 2009-01-29 | ツェットエフ、レンクジステメ、ゲゼルシャフト、ミット、ベシュレンクテル、ハフツング | ステアリング装置の軸に対する半径方向可動軸受 |
JP4943430B2 (ja) * | 2005-07-27 | 2012-05-30 | ツェットエフ、レンクジステメ、ゲゼルシャフト、ミット、ベシュレンクテル、ハフツング | ステアリング装置の軸に対する半径方向可動軸受 |
JP2017222257A (ja) * | 2016-06-15 | 2017-12-21 | 日立オートモティブシステムズ株式会社 | パワーステアリング装置 |
Also Published As
Publication number | Publication date |
---|---|
US20070251758A1 (en) | 2007-11-01 |
JP4716679B2 (ja) | 2011-07-06 |
US20060117889A1 (en) | 2006-06-08 |
EP1637769A1 (en) | 2006-03-22 |
US7455148B2 (en) | 2008-11-25 |
US7455149B2 (en) | 2008-11-25 |
JP2005042913A (ja) | 2005-02-17 |
US20070251757A1 (en) | 2007-11-01 |
US7360467B2 (en) | 2008-04-22 |
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