US20020121401A1 - Electric motor assist type power steering apparatus - Google Patents

Electric motor assist type power steering apparatus Download PDF

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Publication number
US20020121401A1
US20020121401A1 US10/079,610 US7961002A US2002121401A1 US 20020121401 A1 US20020121401 A1 US 20020121401A1 US 7961002 A US7961002 A US 7961002A US 2002121401 A1 US2002121401 A1 US 2002121401A1
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US
United States
Prior art keywords
worm shaft
shaft
worm
electric motor
end part
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US10/079,610
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English (en)
Inventor
Yasuo Shimizu
Katsuji Watanabe
Yasuhiro Terada
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Honda Motor Co Ltd
Original Assignee
Honda Motor Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Honda Motor Co Ltd filed Critical Honda Motor Co Ltd
Assigned to HONDA GIKEN KOGYO KABUSHIKI KAISHA reassignment HONDA GIKEN KOGYO KABUSHIKI KAISHA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SHIMIZU, YASUO, TERADA, YASUHIRO, WATANABE, KATSUJI
Publication of US20020121401A1 publication Critical patent/US20020121401A1/en
Priority to US10/695,150 priority Critical patent/US6832662B2/en
Abandoned legal-status Critical Current

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Classifications

    • 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
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/50—Other types of ball or roller bearings
    • F16C19/507—Other types of ball or roller bearings with rolling elements journaled in one of the moving parts, e.g. stationary rollers to support a rotating part
    • 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
    • F16C39/00—Relieving load on bearings
    • F16C39/02—Relieving load on bearings using mechanical means
    • 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
    • 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
    • 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
    • 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
    • Y10T74/19623—Backlash take-up
    • 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
    • Y10T74/19842—Distribution of pressure

Definitions

  • the present invention relates to an electric motor assist type power steering apparatus, which assists the steering effort of a driver by making the electric motor power act on a steering system directly.
  • An electric motor assist type power steering apparatus (hereinafter defined as an electric power steering apparatus) assists the steering force of a driver by making use of the driving force of an electric motor directly.
  • a vehicle, on which an electric power steering apparatus is mounted, is widely spreads, and according to the electric poser steering apparatus, since a movement of the steering becomes light, a driver operates the steering without strong force.
  • a pinion assist type electric power steering apparatus in which a worm shaft and a worm wheel are used as the means for transmitting the driving force of an electric motor, is known.
  • the electric power steering apparatus disclosed in the Japanese patent unexamined patent publication H11-43062, is one example thereof.
  • an electric motor 51 for adding an assist steering force to a steering shaft, which is rotated by the operation of the steering is provided.
  • the worm shaft 52 is connected to the electric motor 51 .
  • a pinion shaft 53 is joined with the steering shaft.
  • the worm wheel 54 which is engaged with a worm gear 52 A of the worm shaft 52 , is fixed to a pinion shaft 53 so that it will be in the coaxial location with respect to the pinion shaft 53 .
  • Both end parts 52 B and 52 C of the worm shaft 52 are held by ball bearings 55 and 56 , respectively.
  • the assist steering force brought by the electric motor 51 is add to the pinion shaft 53 through the worm gear 52 A and the worm wheel 54 which are engaged together. By adding this assist steering force, the steering force required for steering operation of a driver is decreased.
  • both end parts of the worm shaft 52 are rotatably held only by the ball bearing 55 and 56 with backlash.
  • the steering must be turned back with smoothly by rotating the electric motor 51 through the worm wheel 54 and worm shaft 52 . If the flexure is arising on the worm shaft 52 , however, since the bending moment affected to the rotation shaft of the worm gear 52 A is decreased by the decreasing of the assist steering force brought by the electric motor 51 , the restorative deformation is arisen for correcting the flexure.
  • the clearance which exceeds a predetermined clearance value may be arose between the worm gear 52 A and the worm wheel 54 as the occurrence of the flexure of the worm shaft 52 .
  • the dispensable backlash between the worm gear 52 A and the worm wheel 54 becomes larger.
  • the assist steering force brought by the electric motor 51 cannot be transmitted to the steering shaft completely.
  • the present invention aim at providing the electric motor assist type power steering apparatus, preferably the pinion assist type electric power steering apparatus, which can prevent the aggravation of the feeling of the steering by preventing the flexure of the worm shaft, and which can transmit the assist steering force of the electric motor to the steering shaft completely.
  • an electric power steering apparatus comprising; an electric motor for adding the assist steering force to the steering system, a controller which drives said electric motor, a rack shaft which steers a steered wheel by displacing along the axial direction thereof, a pinion shaft which is engaged with said rack shaft through the rack-and-pinion mechanism, a worm shaft which is rotated by the electric motor, and a worm wheel which is engaged with said worm shaft and is integrally arranged with the pinion shaft, one end part of the worm shaft is joined with the electric motor, and holding means, which holds one end part and another end part of the worm shaft on allowing the rotation thereof, is further arranged.
  • one end part and another end part of the worm shaft are held without play.
  • the worm shaft in the conventional manner, is held with play, thus the flexural rigidity is not so high and the flexure of the worm shaft is easily arisen.
  • the worm shaft in the present invention, is held without play, thus the worm shaft can be held with high flexural rigidity.
  • said holding means is composed of plural ball bearings which hold one end part of the worm shaft, and plural ball bearings which hold the another end part of the worm shaft.
  • both end parts of the worm shaft are held without play by plural of ball bearings.
  • the holding of the worm shaft can be carried out on keeping the rotating condition at the both ends of the worm shaft into the smooth condition.
  • the holding of the worm shaft can be carried out using ball bearings, which are general-purpose parts without using the specific parts. Therefore, the contribution to a cost reduction may be attained.
  • said holding means is composed of plural ball bearings which hold the one end part of the worm shaft, and a needle bearing which holds another end par of the worm shaft.
  • one end part side of the worm shaft joined with the electric motor is held by the plural of ball bearings. Since one end part of the worm shaft is joined with the electric motor, flexural rigidity in the one end part of the worm shaft is comparatively high, and that of in the another end part becomes low a little.
  • an electric power steering apparatus comprising; an electric motor for adding the assist steering force to the steering system, a controller which drives said electric motor, a rack shaft which steers a steered wheel by displacing along the axial direction thereof, a pinion shaft which is engaged with said rack shaft through the rack-and-pinion mechanism, a worm shaft which is rotated by the electric motor, a worm wheel which is engaged with said worm shaft and is integrally arranged with the pinion shaft, end part holding means which holds the one end part of the worm shaft on allowing the rotation of the worm shaft, and center supporting means which holds the center part in the longitudinal direction of the worm shaft on allowing the rotation of the worm shaft, wherein one end part of said worm shaft is joined with the electric motor.
  • said center supporting means has urging means which gives the urging force towards the engaging part between the worm shaft and the worm wheel from the opposite direction with respect to the engaging part.
  • the urging means which urges the worm shaft to the engaging part side with respect to the worm wheel is arranged. Since the flexure of the worm shaft is prevented, and the worm shaft is pressed to the worm wheel with sufficient force, the clearance between the worm shaft and the worm wheel is maintained within the predetermined range. Thus, the occurrence of the unpleasant backlash between the worm gear and the worm wheel can be prevented, and the certain transmission of the rotation of the worm shaft to the worm wheel can be achieved.
  • said center supporting means has a first roller and a second roller which are touched with the worm shaft and press the worm shaft toward the engaging part between the worm shaft and the worm wheel.
  • the first roller and the second roller which are fitted with the worn shaft, is applied to the engaging part between the worm shaft and the worm wheel.
  • the displacement in the ups-and-downs directions of the worm shaft is restricted, and the worm shaft is applied to the engaging part between the worm shaft and the worm wheel. Since the roller is used, the supporting mechanism with slightest fiction can be obtained.
  • FIG. 1 is a whole block diagram of the electric power steering apparatus according to the first preferred embodiment of the present invention.
  • FIG. 2 is a plan view of the substantial part of the electric power steering apparatus according to the first preferred embodiment of the present invention.
  • FIG. 3 is a sectional view along the line X-X in FIG. 2.
  • FIG. 4A is an explaining view of the model of the beam both ends part of which are held without play, and the bending moment applied to the beam.
  • FIG. 4B is an explaining view of the model of the beam both ends part of which are held with play, and the bending moment applied to the beam.
  • FIG. 2 is a plan view of the substantial part of the electric power steering apparatus according to the second preferred embodiment of the present invention.
  • FIG. 6 is a plan view of the substantial part of the electric power steering apparatus according to the third preferred embodiment of the present invention.
  • FIG. 6 is a sectional view along the line Y-Y in FIG. 2.
  • FIG. 8 is a plan exploded view of the substantial part of the conventional electric power steering.
  • FIG. 1 is a block diagram of the electric power steering apparatus according to the present invention.
  • FIG. 2 is a plan view of the principal part of the electric power steering apparatus.
  • FIG. 3 is a sectional view along the line X-X in FIG. 2.
  • an electric power steering apparatus 1 has a steering 2 .
  • the steering 2 is connected to a pinion shaft 4 through a steering shaft 3 .
  • a torque sensor 5 and a torque transmitter 6 are attached to the pinion shaft 4 .
  • the torque sensor 5 detects the steering torque add to the steering system.
  • the torque transmitter 6 is an assistor, and connected to an electric motor 7 , which adds the assists steering force to the steering system.
  • a pinion 4 A arranged at the bottom part of the pinion shaft 4 , is engaged with a gear rack 8 A provided on a rack shaft 8 .
  • the torque sensor 5 is connected to a control unit 10 , and outputs the toque signal to the control unit 10 .
  • the control unit 10 computes the assist steering force using at least the torque signal T outputted form the torque sensor 5 , and outputs the electric motor control signal VO to the electric motor 7 , and thus the electric motor 7 is controlled.
  • the torque transmitter 6 has a worm wheel 11 , which is fixed to the pinion shaft 4 so that it might be in the coaxial location with respect to the pinion shaft 4 .
  • a worm shaft 12 is joined to the rotation shaft of the electric motor 7 through the coupling and the like.
  • a worm gears 12 A provided on the worm shaft 12 is engaged with the worm wheel 11 .
  • One end part 12 B of the worm shaft 12 is held by a first ball bearing 14 A and a second ball bearing 14 B, which are arranged in the adjoining location along the longitudinal direction of the worm shaft 12 , on allowing the rotation of the worm shaft 12 .
  • the ball bearings 14 A and 14 B are a holding means, which holds the one end part 12 B of the worm shaft 12 with sufficient flexural rigidity. In other words, the holding means restricts the flexure of the worm shaft 12 .
  • Another end part 12 C of the worm shaft 12 is held by a first ball bearing 15 A and a second ball bearing 15 B, which are arranged in the adjoining location along the longitudinal direction of the worm shaft 12 , on allowing the rotation of the worm shaft 12 .
  • the ball bearing 15 A and 15 B are also a holding means, which holds the one end part 12 C of the worm shaft 12 with sufficient flexural rigidity. In other words, the holding means restricts the flexure of the worm shaft 12 .
  • the location interval L 1 between the ball bearing 14 A and 14 B and the location interval L 2 between the ball bearing 15 A and 15 B are same.
  • the location interval L 1 and the location interval L 2 are established as long as possible so that it can restrict the flexure of the worm shaft 12 efficiently.
  • the torque sensor 5 detects the steering torque.
  • the steering torque detected by the torque sensor 5 is output to the control unit 10 as a torque signal T.
  • the assist steering force which is brought by the electric motor 7 and add to the steering system, is computed using at least the steering torque represented by the torque signal T on considering the factors such as traveling speed and the steering angle.
  • the electric motor control signal Vo is output to the electric motor 7 from the control unit 10 .
  • the electric motor 7 is driven by the electric motor control signal Vo, and rotates the worm shaft 12 of shown in FIG. 2.
  • One end part 12 B of the worm shaft 12 is held by the ball bearing 14 A and 14 B while the worm shaft 12 is rotating.
  • Another end part 12 C of the worm shaft 12 is also held by the ball bearing 15 A and 15 B.
  • both end parts of the worm shaft 12 is in the held condition by holding both end part 12 B and 12 C of the worm shaft 12 on allowing the rotation of the worm shaft.
  • FIG. 4A is an explaining view of the bending moment in the case that the force P is applied to the center in the longitudinal direction of a beam from the upper direction, wherein both end parts of the beam are rigidly held without play (play means it has a loose fit).
  • FIG. 4A is an explaining view of the bending moment in case that the force P is applied to the center in the longitudinal direction of a beam from the upper direction, wherein both end parts of the beam are held with play (play means it has a loose fit).
  • the maximum flexural amount ( ⁇ max) of the beam H is formulated as formula (1).
  • the flexural amount of the beam H, wherein both end parts are rigidly held without play becomes to one fourth with respect to the case where both end parts are held with play.
  • the flexural amount of the beam H can be smaller than that of the beam H, both end parts of which are held with play.
  • the beam with sufficient flexural rigidity and with high flexure resistance can be supplied when both end parts of the beam are held without play.
  • the holding of the beam member can be carried out with sufficient rigidity than the case where the both end parts are supported with play, and thus the maximum flexural amount of the beam H can be smaller.
  • the worm shaft 12 is rigidly held by the ball bearing 14 A, 14 B, 15 A and 15 B without play. Since the same reason as described in the case of beam H can be applicable, the worm shaft 12 according to the present invention can be held with sufficient flexural rigidity as compared to the conventional holding manner.
  • the difference between the flexural rigidity at one end part 12 B and at the another end part 12 C of the worm shaft 12 may be arisen.
  • the flexural rigidity of another end part 12 c side can be stronger than that of one end part 12 B side, by establishing the interval between the ball bearing 15 A and 15 B wider than that of between the ball bearing 14 A and 14 B. Therefore, since one end part 12 B and another end part 12 C are rigidly held with the uniform flexural rigidity depending on the strength of the connecting part between the rotation axis of the electric motor 7 and the worm shaft 12 , the prevention of the flexure of the worm shaft 12 can be achieved more certainly.
  • FIG. 5 is a plan sectional view showing a substantial part of the electric power steering apparatus according to the present invention.
  • an electric power steering apparatus 20 according to the present preferred embodiment, only the construction of the torque transmitter is differing from the electric power steering apparatus 1 .
  • the explanation is mainly carried out about the different components, and the same components as that of explained in the first embodiment is emitted and indicates as the same symbol.
  • a torque transmitter 21 according to the present second preferred embodiment of the electric power steering apparatus 20 , has a worm wheel 11 fixed to the pinion shaft 4 so that it might be in the coaxial location with respect to the pinion shaft 4 .
  • a worm gear 12 is joined to the electric motor 7 .
  • the worm gears 12 A provided to the worm shaft 12 is engaged with the worm wheel 11 .
  • One end part 12 B of the worm shaft 12 is held by the ball bearing 14 A and 14 B which are arranged in the adjoining location along the longitudinal direction of the worm shaft 12 .
  • another end part 12 C of the worm shaft 12 is held by a needle bearing 22 on allowing the rotation around the axis.
  • the electric power steering apparatus 20 according to the present preferred embodiment differs in that the another end part 12 C of the worm shaft 12 is supported without play on allowing the rotation.
  • one end part 12 B of the worm shaft 12 is held without play by the two of ball bearings 14 A and 14 B, and another end part 12 C of the worm shaft 12 is held without play by the needle bearing 22 .
  • needle bearing 22 since needle rollers (located at inner-side and outer-side in figure) are contacting with the worm shaft 12 along the longitudinal direction of the worm shaft 12 , wide range of the worm shaft 12 is held by the needle roller.
  • flexural resistance in the diameter direction at the another end part 12 C of the worm shaft 12 where is supported by the needle bearing 22 is higher than one end part. Therefore, since another end part 12 C is held by the needle bearing 22 , the flexural rigidity at the another end part 12 C of the worm gear 12 is also higher than the one end part 12 B where the worm gear 12 is held by the ball bearing 14 A and 14 B.
  • the flexural rigidity at one end part 12 B and another end part 12 C of worm shaft 12 can be uniform by holding the another ends part 12 C using the needle bearing 22 , which gives the superior flexural resistance, even if the rigidity at the one ends part 12 B becomes high as a result of the firmly connection between the rotating shaft of the electric motor 7 and the worm shaft 12 .
  • FIG. 6 is a plan sectional view of the substantial part of the electric power assist type steering apparatus according to the present invention.
  • FIG. 7 is sectional view along the line Y-Y in FIG. 6.
  • a torque transmitter 21 according to the present second preferred embodiment of the electric power steering apparatus 30 , has a worm wheel 11 fixed to the pinion shaft 4 so that it might be in the coaxial condition with the pinion shaft 4 .
  • the worm gear 12 is joined to the electric motor 7 , and a worm gear 12 A provided thereto is engaged with the worm wheel 11 .
  • One end part 12 B of the worm shaft 12 is held by a ball bearing 32 in the condition the rotation of the worm shaft 12 might be allowed.
  • Another end part 12 C is also held by a ball bearing 33 in the condition where the rotation of the worm shaft 12 might be allowed.
  • a central holding means 35 is arranged at the almost central part in the longitudinal direction of the worm shaft 12 .
  • the central holding means 35 is positioned so that the worm shaft 12 might be sandwiched between the worm wheel 11 and the central holding means 35 , and has a urging means 34 which crowds the worm shaft 12 toward the direction of the worm wheel 11 .
  • this urging means 34 the worm shaft 12 is pressed toward the worm wheel 11 from the opposite direction side with respect to the engaging part where the worm gear 12 A and worm wheel 11 are engaged together.
  • This urging means 34 is arranged for pressing the worm shaft 12 to the engaging part of the worm wheel 11 , and is composed of a spring 36 , an upper roll 37 , a lower roll 38 , and a roller holder 39 (see FIG. 7).
  • the urging means 34 has the upper roll 37 and the lower roll 38 which are arranged at the opposite side with respect to the engaging part where the worm wheel 11 and the worm gear 12 A of the worm shaft 12 are engaged together.
  • the urging means 34 also has a roller holder 39 , which rotatably supports the upper roll 38 and the lower roll 39 , and the spring 36 , which press the roller holder 39 towards the worm shaft 12 urgently.
  • the upper roll 37 and the lower roll 38 are fit with the worm gear 12 A, respectively, and transmit the urgent force brought by the spring 36 to the worm gear 12 A.
  • the rotation shafts of the upper roll 37 and the lower roll 38 are supported by the roller folder 39 and thus the movement in the ups-and-downs directions thereof is restricted.
  • the center holding means 35 In the electric power steering apparatus 30 according to the present preferred embodiment, about the center part in the longitudinal direction of the worm shaft 12 is supported by the center holding means 35 .
  • the flexural degree of the worm shaft 12 conventionally, tends to be maximum at the central part in the longitudinal direction of the worm shaft 12 .
  • the occurrence of the flexure of the worm shaft 12 is efficiently prevented. As a result of this prevention, the aggravation arose at the time of turning back of the steering is prevented, and thus the prevention of the aggravation of the steering feeling and the certain transmission of the steering force by the electric motor to the pinion shaft can be achieved.
  • the central part between one end part and the another end part of the worm shaft 12 is supported, the scattering in the flexural resistance in the longitudinal direction of the worm shaft 12 can be smaller.
  • the gaps in the steering feeling depending on the turning direction of the steering can be smaller.
  • the center holding means 35 has the urging means 34 , the urgent force brought by the spring 36 is transmitted to the worm shaft 12 through the upper roll 37 and the lower roll 38 . Accordingly, the clearance between the worm gear 12 A and the worm wheel 11 is maintained within the predetermined clearance even if the clearance, which exceeds a predetermined clearance value, come close to arising as a result of the occurrence of slight flexure of the worm gear 12 .
  • both end parts of the worm gear 12 are held by the ball bearings 32 and 32 , but the holding manner of the worm gear 12 is not restricted to this case.
  • the holding manner for example, in which the worm gear 12 is held without the ball bearing arranged at another end part of the worm gear can be applicable as long as the flexural resistance brought by the center holding means is acceptable.
  • the application of the present invention is not restricted to the above-described case.
  • the application to the another type of construction may be acceptable as long as the it has a construction that the diving force brought by the electric motor is add to the pinion shaft, which is joined to the rack shaft and steers the steering wheel.
  • the steer-by-wire mechanism which steers the steered wheel only by the driving force, which is brought by the electric motor and is controlled by the electric signal, and the four-wheel-steering mechanism and the like are considerable.
  • the worm shaft 12 is held with sufficient flexural rigidity by holding the worm shaft without play. According to this invention, since the flexure of the worm shaft 12 is prevented, the aggravation caused by the flexure of the worm shaft 12 at the time of turning back of the steering is prevented. As a result of this prevention, the aggravation of the steering feeling and the certain transmission of the steering force, which is brought by the electric motor, to the pinion shaft can be achieved.
  • one end part and another end part of the worm shaft are held by plural of ball bearings, respectively.
  • the worm shaft is held without play on maintaining the smooth rotation of the worm gear. Since the ball bearing which are general-purpose components is used, furthermore, it can contribute to a cost reduction.
  • both end parts of the worm shaft are held with the uniform flexural rigidity by holding the another end part side, in which the flexural rigidity is low a little, by the needle bearing.
  • the flexure of the worm shaft is certainly prevented and also the occurrence of the feeling gap between in the case the steering is turned back in the anticlockwise direction and in the case the steering is turned back in the clockwise direction can be decreased. the certain transmission of the steering force brought by the electric motor 7 to the pinion shaft 3 is achieved.
  • the occurrence of the flexure of the worm shaft can be prevented while the worm shaft is made into the rotatable condition. According to this invention, the aggravation of the steering feeling and the certain transmission of the steering force brought by the electric motor to the pinion shaft can be achieved.
  • the worm shaft is pressed to the engaging part between the worm shaft and the worm wheel by the urgent force of the urging means with the suitable force, the clearance between the worm shaft and the worm wheel can be maintained within the predetermined ranges. According to the present invention, since the occurrence of the backlash between the worm gear and the worm wheel is prevented, the rotation of the worm shaft is certainly transmitted to the worm wheel.
  • the displacement in the ups-and-downs directions of the worm shaft is restricted.
  • the worm shaft is crowed toward the engaging part with worm wheel on allowing the rotation of the worm shaft. According to the invention, since the roller is used, the unpleasant friction with respect to the worm gear can be reduced.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Power Steering Mechanism (AREA)
US10/079,610 2001-03-05 2002-02-19 Electric motor assist type power steering apparatus Abandoned US20020121401A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US10/695,150 US6832662B2 (en) 2001-03-05 2003-10-27 Electric motor assist type power steering apparatus

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2001-060266 2001-03-05
JP2001060266A JP3888607B2 (ja) 2001-03-05 2001-03-05 電動パワーステアリング装置

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US10/079,610 Abandoned US20020121401A1 (en) 2001-03-05 2002-02-19 Electric motor assist type power steering apparatus
US10/695,150 Expired - Fee Related US6832662B2 (en) 2001-03-05 2003-10-27 Electric motor assist type power steering apparatus

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JP (1) JP3888607B2 (de)
DE (1) DE10208725B4 (de)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004074071A3 (en) * 2003-02-20 2004-12-02 Nsk Ltd Electric-powered power steering apparatus
US20040245040A1 (en) * 2001-12-03 2004-12-09 Hiroshi Eda Electric power steering device
US20070205680A1 (en) * 2006-03-06 2007-09-06 Honda Motor Co., Ltd. Electric motor and electric power steering apparatus
US20100293736A1 (en) * 2007-10-30 2010-11-25 Valeo Systemes D'essuyage Electric-motor auxiliary drive for vehicles, and method for producing and mounting a drive of this type
EP1887254A3 (de) * 2006-08-11 2010-12-01 JTEKT Corporation Elektrische Servolenkung
US20110017013A1 (en) * 2008-03-06 2011-01-27 Antonius Bader System having a gear unit
CN103112489A (zh) * 2011-11-16 2013-05-22 株式会社捷太格特 车辆用转向装置
US20140311267A1 (en) * 2013-04-19 2014-10-23 Ford Global Technologies, Llc Worm gear
US20150144416A1 (en) * 2012-06-22 2015-05-28 Takata AG Superposition drive for a superimposed steering system of a motor vehicle
US20200287439A1 (en) * 2019-03-05 2020-09-10 Nidec Corporation Brushless motor and electronic products having the brushless motor
US11088588B2 (en) * 2015-08-10 2021-08-10 Nidec Corporation Motor with an upper bearing including a washer, a lower bearing, and bearing holding portions
CN114165576A (zh) * 2021-11-23 2022-03-11 合众新能源汽车有限公司 一种汽车电动转向减速箱齿轮轴固定结构
US11346435B2 (en) * 2018-05-18 2022-05-31 Mando Corporation Reducer of electric power steering apparatus

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Cited By (26)

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US7188700B2 (en) 2001-12-03 2007-03-13 Nsk Ltd. Electric power steering apparatus
US20040245040A1 (en) * 2001-12-03 2004-12-09 Hiroshi Eda Electric power steering device
US7077235B2 (en) 2001-12-03 2006-07-18 Nsk Ltd. Electric power steering device
US20060191738A1 (en) * 2001-12-03 2006-08-31 Hiroshi Eda Electric power steering apparatus
US20080217097A1 (en) * 2003-02-20 2008-09-11 Nsk Ltd. Electric-powered power steering apparatus
US7100734B2 (en) 2003-02-20 2006-09-05 Nsk Ltd. Electric-powered power steering apparatus
WO2004074071A3 (en) * 2003-02-20 2004-12-02 Nsk Ltd Electric-powered power steering apparatus
US20070205680A1 (en) * 2006-03-06 2007-09-06 Honda Motor Co., Ltd. Electric motor and electric power steering apparatus
GB2435912A (en) * 2006-03-06 2007-09-12 Honda Motor Co Ltd Electric motor and electric power steering apparatus
GB2435912B (en) * 2006-03-06 2008-05-14 Honda Motor Co Ltd Electric motor and electric power steering apparatus
US8294311B2 (en) 2006-03-06 2012-10-23 Honda Motor Co., Ltd. Electric motor and electric power steering apparatus
EP1887254A3 (de) * 2006-08-11 2010-12-01 JTEKT Corporation Elektrische Servolenkung
US8598756B2 (en) * 2007-10-30 2013-12-03 Valeo Systemes D'essuyage Electric-motor auxiliary drive for vehicles, and method for producing and mounting a drive of this type
US20100293736A1 (en) * 2007-10-30 2010-11-25 Valeo Systemes D'essuyage Electric-motor auxiliary drive for vehicles, and method for producing and mounting a drive of this type
US20110017013A1 (en) * 2008-03-06 2011-01-27 Antonius Bader System having a gear unit
EP2255108B1 (de) * 2008-03-06 2013-10-23 SEW-Eurodrive GmbH & Co System mit getriebe
US9958052B2 (en) 2008-03-06 2018-05-01 Sew-Eurodrive Gmbh & Co. Kg System having a gear unit
CN103112489A (zh) * 2011-11-16 2013-05-22 株式会社捷太格特 车辆用转向装置
US20150144416A1 (en) * 2012-06-22 2015-05-28 Takata AG Superposition drive for a superimposed steering system of a motor vehicle
US9499191B2 (en) * 2012-06-22 2016-11-22 Takata AG Superposition drive for a superimposed steering system of a motor vehicle
US20140311267A1 (en) * 2013-04-19 2014-10-23 Ford Global Technologies, Llc Worm gear
US10634217B2 (en) * 2013-04-19 2020-04-28 Ford Global Technologies, Llc Worm gear
US11088588B2 (en) * 2015-08-10 2021-08-10 Nidec Corporation Motor with an upper bearing including a washer, a lower bearing, and bearing holding portions
US11346435B2 (en) * 2018-05-18 2022-05-31 Mando Corporation Reducer of electric power steering apparatus
US20200287439A1 (en) * 2019-03-05 2020-09-10 Nidec Corporation Brushless motor and electronic products having the brushless motor
CN114165576A (zh) * 2021-11-23 2022-03-11 合众新能源汽车有限公司 一种汽车电动转向减速箱齿轮轴固定结构

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DE10208725B4 (de) 2006-04-13
US6832662B2 (en) 2004-12-21
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US20040094353A1 (en) 2004-05-20
JP2002264827A (ja) 2002-09-18

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