WO2017135141A1 - ウォームホイール、ウォーム減速機、及びウォームホイールの製造方法 - Google Patents
ウォームホイール、ウォーム減速機、及びウォームホイールの製造方法 Download PDFInfo
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- WO2017135141A1 WO2017135141A1 PCT/JP2017/002680 JP2017002680W WO2017135141A1 WO 2017135141 A1 WO2017135141 A1 WO 2017135141A1 JP 2017002680 W JP2017002680 W JP 2017002680W WO 2017135141 A1 WO2017135141 A1 WO 2017135141A1
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- Prior art keywords
- wheel element
- worm
- wheel
- axial
- axial direction
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Images
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
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/16—Making multilayered or multicoloured articles
-
- 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
- F16H55/06—Use of materials; Use of treatments of toothed members or worms to affect their intrinsic material properties
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/14—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/26—Moulds
- B29C45/27—Sprue channels ; Runner channels or runner nozzles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/26—Moulds
- B29C45/27—Sprue channels ; Runner channels or runner nozzles
- B29C45/2701—Details not specific to hot or cold runner channels
- B29C45/2708—Gates
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C19/00—Bearings with rolling contact, for exclusively rotary movement
- F16C19/02—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows
- F16C19/14—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load
- F16C19/16—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with a single row of balls
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- 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
- F16H55/17—Toothed wheels
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2705/00—Use of metals, their alloys or their compounds, for preformed parts, e.g. for inserts
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- B29L2015/00—Gear wheels or similar articles with grooves or projections, e.g. control knobs
- B29L2015/003—Gears
-
- 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
- B62D5/0403—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by constructional features, e.g. common housing for motor and gear box
-
- 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
- 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
- F16H55/06—Use of materials; Use of treatments of toothed members or worms to affect their intrinsic material properties
- F16H2055/065—Moulded gears, e.g. inserts therefor
Definitions
- the present invention relates to a worm wheel including an inner wheel element serving as a core and an outer wheel element made of synthetic resin having a tooth portion, a worm speed reducer including the worm wheel, and a method of manufacturing the worm wheel. And about.
- FIG. 20 to 25 show an example of an electric power steering apparatus which has been conventionally described in Patent Document 1 and the like.
- a front end portion of the steering shaft 2 having the steering wheel 1 attached to the rear end portion is rotatably supported in the housing 3.
- a worm wheel 4 is fixed to a portion that is rotationally driven by the steering shaft 2.
- a worm shaft 6 is connected to the output shaft of the electric motor 5.
- the worm wheel 18 provided on the outer peripheral surface of the intermediate portion in the axial direction of the worm shaft 6 and the worm wheel tooth portion 19 provided on the outer peripheral surface of the worm wheel 4 are engaged with each other, whereby the worm wheel is turned from the electric motor 5. 4, it is possible to apply auxiliary torque (auxiliary power) having a predetermined magnitude in a predetermined direction.
- the worm wheel 4 is externally fitted and fixed to an intermediate portion in the axial direction of the output shaft 7 serving as an output portion of the auxiliary torque, and rotates together with the output shaft 7.
- the output shaft 7 has a front end of the steering shaft 2 through a torsion bar 9 in a state in which both end portions of the intermediate portion in the axial direction are supported by the pair of rolling bearings 8a and 8b in the housing 3 so as to be rotatable only. Connected to the part.
- the electric motor 5 rotationally drives the worm shaft 6 according to the direction and magnitude of the steering torque applied from the steering wheel 1 to the steering shaft 2 detected by the torque sensor 10, and gives auxiliary torque to the output shaft 7.
- the rotation of the output shaft 7 is transmitted to the pinion shaft 14 serving as an input portion of the steering gear unit 13 via the pair of universal joints 11a and 11b and the intermediate shaft 12, and a desired steering angle is given to the steered wheels. .
- the worm wheel 4 is formed by combining a metal inner wheel element 15 as a core material and a synthetic resin outer wheel element 16. That is, in the worm wheel 4, a portion that is externally fitted and fixed to the output shaft 7 is made of a metal and annular inner wheel element 15, and a portion including the worm wheel tooth portion 19 is made of a synthetic resin outer wheel element 16. Yes.
- the outer wheel element 16 is made of a synthetic resin, thereby facilitating the work for forming the worm wheel tooth portion 19 on the outer peripheral surface of the worm wheel 4 (cost reduction) and the worm shaft 6 worm. Reduction of rattling noise generated at the meshing portion between the tooth portion 18 and the worm wheel tooth portion 19 of the worm wheel 4 can be achieved.
- the outer wheel element 16 is made of a synthetic resin, and the radial outer end portion of the inner wheel element 15 is embedded over the entire circumference along with injection molding (by insert molding). Further, the outer peripheral surface of the inner wheel element 15 is provided with a (gear-like) concavo-convex portion 17 in the circumferential direction, and a plurality of concave portions constituting the concavo-convex portion 17 is made of a synthetic resin constituting the outer wheel element 16. The holding force in the rotational direction of the outer wheel element 16 with respect to the inner wheel element 15 is increased by inserting a part thereof.
- the outer wheel element 16 embeds only the radially outer end of the inner wheel element 15 to secure the holding force of the outer wheel element 16 against the inner wheel element 15. Yes. For this reason, there is still room for improvement in terms of improving the holding power.
- the concave and convex portions 17 in the circumferential direction are provided on the outer peripheral surface of the inner wheel element 15, and the synthetic resin constituting the outer wheel element 16 is formed in a plurality of concave portions constituting the concave and convex portions 17. Part of it is included.
- the radial thickness of the portion that overlaps the outer side in the radial direction with respect to the concavo-convex portion 17 is the portion where the plurality of teeth 20, 20 constituting the worm wheel tooth portion 19 are located.
- the sizes may be different from each other (see FIGS. 24 to 25).
- the amount of molding shrinkage at the time of injection molding is different ⁇ in the portion where the radial thickness is large (for example, the ⁇ portion in FIG. 25), Because the thickness in the radial direction is small (for example, the ⁇ portion in FIG. 25) ⁇ , there is a difference in the size of the plurality of teeth 20 and 20 after molding. 19 may cause a manufacturing error such as a pitch error.
- the present invention has been invented to realize a structure capable of improving the holding force of the outer wheel element made of synthetic resin with respect to the inner wheel element serving as the core material in view of the above-described circumstances.
- the worm wheel of the present invention includes an inner wheel element and an outer wheel element.
- the inner wheel element has a first annular recess provided on one side surface in the axial direction so as to be recessed in the axial direction.
- the outer wheel element is made of synthetic resin, has a worm wheel tooth portion on the outer peripheral surface, and from the inner diameter side peripheral surface constituting the inner surface of the first annular recess among the surfaces of the inner wheel element, A continuous range from the outer peripheral surface of the inner wheel element to the radially inner end portion (the portion located radially inward of the radial center position) on the other axial side surface of the inner wheel element.
- the inner wheel element is embedded so as to cover the surface.
- the material of the inner wheel element can be metal, for example, it has better heat resistance than the material of the outer wheel element, and when the outer wheel element is injection molded Use a synthetic resin that is not easily affected by heat (for example, the synthetic resin constituting the outer wheel element is a thermoplastic resin, and the synthetic resin constituting the inner wheel element is a thermosetting resin). You can also.
- a second annular recess is provided in the axially recessed state on the other side surface in the axial direction of the inner wheel element, and the outer wheel element is Out of the surface of the wheel element, from the inner peripheral surface forming the inner surface of the first annular recess to the inner peripheral surface forming the inner surface of the second annular recess through the outer peripheral surface of the inner wheel element. It is possible to employ a configuration in which the inner wheel element is embedded so as to cover a continuous range of the entire area.
- At least one of the outer peripheral side peripheral surface and the inner peripheral side peripheral surface constituting the inner surface of the second annular recess is provided with the inner wheel element. It is possible to employ a configuration in which an inclined surface portion that is inclined in a direction in which the width dimension in the radial direction of the second annular recess increases toward the other side in the axial direction with respect to the central axis.
- the outer peripheral side peripheral surface constituting the inner surface of the second annular recess is not inclined with respect to the inclined surface portion and the central axis of the inner wheel element. It is possible to adopt a configuration provided with a surface portion.
- the inclined surface portion and the non-inclined surface portion that does not incline with respect to the central axis of the inner wheel element on the inner peripheral surface constituting the inner surface of the second annular recess. And a configuration provided with can be adopted.
- the worm wheel of the present invention for example, in the inner wheel element, the first annular recess and the portion positioned radially outward from the second annular recess, and the bottom surface of the first annular recess, The portions sandwiched between the bottom surfaces of the second annular recesses and the axial dimensions of both side portions sandwiching the center position of the inner wheel element in the axial direction are equal to each other. Then, in the axial direction with respect to a portion located radially outside of the inner wheel element and a portion of the inner wheel element located radially outside of the first annular recess and the second annular recess.
- the overlapping portions can adopt a configuration in which the axial dimensions of both side portions sandwiching the center position of the inner wheel element in the axial direction are equal to each other. .
- the surface of the inner wheel element is provided with an uneven portion in the circumferential direction, and a part of the synthetic resin constituting the outer wheel element is the uneven portion. It is possible to adopt a configuration that enters into the concave portion that constitutes.
- grooved part is provided in the inner surface of said 1st annular recessed part or said 2nd annular recessed part can be employ
- the uneven portion is provided on the outer diameter side peripheral surface or the inner diameter side peripheral surface that constitutes the inner surface of the first annular recess or the second annular recess. .
- the concavo-convex portion is provided over the entire axial length of the outer diameter side circumferential surface and the inner diameter side circumferential surface constituting the inner surface of the first annular recess and the second annular recess, It is possible to adopt a configuration in which a part of the synthetic resin that constitutes the wheel element enters the entire concave portion that constitutes the uneven portion.
- the uneven portion is provided on the outer diameter side peripheral surface or the inner diameter side peripheral surface constituting the inner surface of the first annular recess or the second annular recess, for example.
- the plurality of teeth constituting the worm wheel tooth portion are formed in a direction inclined in a predetermined direction with respect to the axial direction of the worm wheel, and a plurality of concave portions and convex portions constituting the concavo-convex portion.
- the structure formed in the direction inclined in the direction opposite to the predetermined direction with respect to the axial direction of the worm wheel can be employed.
- a sub-recess is provided in a state of being recessed radially outward in a portion located on the side, and a part of the synthetic resin constituting the outer wheel element enters the sub-recess. it can.
- the cross-sectional shape of the sub-recessed portion with respect to a virtual plane including the central axis of the inner wheel element is such that the width dimension in the axial direction becomes smaller from the opening on the inner diameter side toward the bottom on the outer diameter side. It is possible to adopt a configuration that is shaped like a letter.
- a configuration in which at least a part of the axial range of the outer peripheral surface of the inner wheel element is a cylindrical surface portion can be adopted.
- both axial end edges of the cylindrical surface portion which is the outer peripheral surface of the inner wheel element
- both axial end edges of the cylindrical surface portion which is the outer peripheral surface of the inner wheel element
- both axial end edges of the cylindrical surface portion can be formed in a circular shape whose axial position does not change with respect to the circumferential direction.
- the surface of the inner wheel element covered by the synthetic resin constituting the outer wheel element for example, the cylindrical surface portion, the surface of the inner wheel element
- the whole surface is a fine uneven surface formed by various processes such as knurling, graining (processing to transfer fine unevenness formed on the surface of hard metal to the surface of the molded product), shot blasting, etc. Can be adopted. If such a configuration is adopted, a part of the synthetic resin that constitutes the outer wheel element enters the concave portion that constitutes the fine uneven surface, and therefore the holding force (adhesion of the outer wheel element with respect to the inner wheel element) ) Can be increased.
- the depth of the recessed part which comprises the said fine uneven surface is 1/10 or less (preferably 1/20 or less, more preferably 1/30 or less) of the radial direction height of the tooth
- the radially inner end portion of the other side surface in the axial direction of the outer wheel element for example, the second annular recess portion of the other side surface in the axial direction of the outer wheel element. It is possible to employ a configuration in which an overhanging portion is provided on the other side in the axial direction from the portion adjacent to the outside in the radial direction at the same radial position as the radially inner end portion.
- the worm speed reducer of the present invention includes a housing, a rotating shaft, a worm wheel, and a worm shaft.
- the rotating shaft is rotatably supported with respect to the housing.
- the worm wheel has a worm wheel tooth portion on an outer peripheral surface and is externally fixed to the rotating shaft.
- the worm shaft has a worm tooth portion at an axially intermediate portion of the outer peripheral surface, and is rotatably supported with respect to the housing in a state where the worm tooth portion is engaged with the worm wheel tooth portion.
- the worm wheel is the worm wheel of the present invention.
- the shaft of the meshing portion between the worm wheel tooth portion and the worm tooth portion in the outer peripheral surface of the inner wheel element constituting the worm wheel For example, at least the shaft of the meshing portion between the worm wheel tooth portion and the worm tooth portion in the outer peripheral surface of the inner wheel element constituting the worm wheel.
- a configuration in which a part in the direction (for example, an axial intermediate part or an axial end part) and the axial range overlapping in the radial direction are cylindrical surface parts can be employed.
- the cylindrical surface portion has an axial range that overlaps with the entire meshing portion in the radial direction.
- the entire outer peripheral surface of the inner wheel element excluding the chamfered portion when a chamfered portion is provided at the axial end edge of the outer peripheral surface
- the structure which becomes can be adopted.
- a portion adjacent to the other side in the axial direction of the worm wheel is provided between the inner ring, the outer ring, the outer peripheral surface of the inner ring, and the inner peripheral surface of the outer ring.
- a rolling bearing for supporting the rotating shaft rotatably with respect to the housing can be provided.
- the other side surface in the axial direction of the outer wheel element constituting the worm wheel can be opposed to one side surface in the axial direction of the inner ring and one side surface in the axial direction of the outer ring in the axial direction.
- the axial distance between the other axial side surface of the outer wheel element and the one axial side surface of the inner ring is the axis distance between the other axial side surface of the outer wheel element and the one axial side surface of the outer ring. It can be made smaller than the direction distance.
- the radially inner end of the other wheel side surface of the outer wheel element constituting the worm wheel is axially other than the portion adjacent to the radially outer side.
- the portion facing the axial one side surface of the inner ring in the axial direction is more than the portion facing the axial one side surface of the outer ring in the axial direction. It is also possible to provide a projecting portion that projects to the other side in the axial direction.
- the method for manufacturing a worm wheel according to the present invention is a method for manufacturing the worm wheel according to the present invention.
- the outer wheel element when the outer wheel element is manufactured by injection molding, the outer wheel element is coupled to the inner wheel element, and insert molding is performed.
- a radially outer end of the disk gate is positioned at a radially inner end on the other axial side of the outer wheel element.
- the worm wheel, the worm speed reducer, and the worm wheel manufacturing method of the present invention as described above, it is possible to improve the holding force of the outer wheel element made of synthetic resin with respect to the inner wheel element.
- Sectional drawing similar to FIG. 22 based on 1st Embodiment of this invention Sectional drawing of the worm wheel based on 1st Embodiment.
- the fragmentary sectional view which shows the state which the worm tooth part and worm wheel tooth part which concern on 1st Embodiment have meshed
- FIG. 3 is a cross-sectional view taken along line AA in FIG. 2 according to the first embodiment.
- Sectional drawing which shows the state which carries out the injection molding of the outer side wheel element based on 1st Embodiment.
- FIG. 21 is an enlarged DD cross-sectional view of FIG. 20.
- FIG. 21 is an enlarged EE sectional view of FIG. 20.
- FIG. 1 shows an electric power steering apparatus incorporating the worm reduction gear of the present embodiment.
- a front end portion of the steering shaft 2 to which the steering wheel 1 (see FIG. 20) is attached at the rear end portion is rotatably supported in the housing 3.
- a worm wheel 4 a is fixed to a portion that is rotationally driven by the steering shaft 2.
- a worm shaft 6 (see FIGS. 3 and 21) is connected to the output shaft of the electric motor 5.
- the worm wheel 4a is externally fitted and fixed to the intermediate portion in the axial direction of the output shaft 7 serving as the output portion of the auxiliary torque, which corresponds to the rotary shaft described in the claims, and rotates together with the output shaft 7.
- the output shaft 7 has a front end of the steering shaft 2 through a torsion bar 9 in a state in which both end portions of the intermediate portion in the axial direction are supported by the pair of rolling bearings 8a and 8b in the housing 3 so as to be rotatable only. Connected to the part.
- the electric motor 5 rotationally drives the worm shaft 6 according to the direction and magnitude of the steering torque applied from the steering wheel 1 to the steering shaft 2 detected by the torque sensor 10, and gives auxiliary torque to the output shaft 7.
- the rotation of the output shaft 7 is transmitted to the pinion shaft 14 (see FIG. 20) serving as the input portion of the steering gear unit 13 via the pair of universal joints 11a and 11b and the intermediate shaft 12, and a desired rudder is transmitted to the steered wheels. A corner is given.
- the pair of rolling bearings 8a and 8b includes inner rings 33a and 33b that are externally supported by the output shaft 7, outer rings 34a and 34b that are internally supported by the housing 3, and an inner ring 33a.
- a plurality of balls 35a each of which is a rolling element, is provided between the inner ring raceway provided on the outer peripheral surface of 33b and the outer ring raceway provided on the inner peripheral surface of the outer ring 34a, 34b. And 35b.
- other types of rolling bearings such as cylindrical roller bearings and tapered roller bearings may be employed as the pair of rolling bearings 8a and 8b.
- the worm wheel 4a is formed by combining an inner wheel element 15a and an outer wheel element 16a.
- the inner wheel element 15a is made of metal in an annular shape (substantially annular shape), and is fitted to the radially central portion so that the axial intermediate portion of the output shaft 7 can be torque-fitted and fixed.
- a hole 21 is provided.
- a first annular recess 22 is formed in a radially intermediate portion on one axial side surface (the left side surface in FIGS. 1 to 4 and 7) of the inner wheel element 15a over the entire circumference and recessed in the axial direction. Is provided.
- the outer diameter side peripheral surface has an axial direction of the outer diameter side peripheral surface.
- An uneven portion 23 (gear-like) in the circumferential direction is provided over the entire length and the entire circumference, in which concave portions 26 and convex portions 27 are alternately arranged in the circumferential direction (at the same pitch in the illustrated example). ing.
- the plurality of concave portions 26 and convex portions 27 constituting the concave and convex portion 23 are, as indicated by a broken line (hidden line) in the upper half portion in FIG. 4, the inner wheel element 15a (worm wheel 4a). Are formed in parallel to the axial direction (the left-right direction in FIGS. 1 to 4 and 7). In other words, the boundary between the concave portion 26 and the convex portion 27 is parallel to the axial direction of the worm wheel 4a.
- the inner peripheral side peripheral surface constituting the inner surface of the first annular recess 22 is a simple cylindrical surface portion 36.
- the bottom surface constituting the inner surface of the first annular recess 22 is a ring-shaped intermediate flat surface portion 37a orthogonal to the central axis of the inner wheel element 15a.
- a second annular recess 38 is formed in the radially intermediate portion of the other side surface in the axial direction of the inner wheel element 15a (the right side surface in FIGS. 1 to 4 and 7) over the entire circumference and recessed in the axial direction. Is provided.
- the outer diameter side peripheral surface is one side (one end portion and intermediate portion) with respect to the axial direction.
- the outer diameter side inclined surface portion 39 provided on the other side (other end portion), and the outer diameter side cylindrical surface portion 40 provided on the other side (continuous).
- the outer diameter side inclined surface portion 39 is a portion corresponding to the inclined surface portion described in the claims, and relates to the radial direction of the second annular recess 38 as it goes to the other side in the axial direction with respect to the central axis of the inner wheel element 15a. It is formed in the shape of a partial conical surface inclined in the direction in which the width dimension increases (the direction toward the radially outer side).
- the outer diameter side cylindrical surface portion 40 is a portion corresponding to the non-inclined surface portion described in the claims, and is formed in a simple cylindrical surface shape that does not incline with respect to the central axis of the inner wheel element 15a. Yes.
- the inner diameter side peripheral surface constituting the inner surface of the second annular recess 38 is composed only of the inner diameter side inclined surface portion 41.
- the inner diameter side inclined surface portion 41 is a portion corresponding to the inclined surface portion described in the claims, and the width of the second annular recess 38 in the radial direction toward the other side in the axial direction with respect to the central axis of the inner wheel element 15a. It is formed in the shape of a partial conical surface inclined in the direction in which the dimension increases (the direction toward the radially inner side).
- the bottom surface constituting the inner surface of the second annular recess 38 is a ring-shaped intermediate plane portion 37b orthogonal to the central axis of the inner wheel element 15a.
- the inner wheel element 15a has the entire outer peripheral surface (excluding these chamfered parts when chamfered portions are provided at both end edges in the axial direction), the radial distance from the central axis of the inner wheel element 15a is The cylindrical surface portion 24 does not substantially change over the entire circumference.
- the cylindrical surface portion 24 has a generatrix parallel to the central axis of the inner wheel element 15a (worm wheel 4a), and is formed in a single cylindrical surface shape whose diameter does not change in the axial direction.
- a radially outer end (from the first annular recess 22) on one axial side surface of the inner wheel element 15a which is a portion that is continuous (directly or via a chamfered portion) with respect to both axial edges of the cylindrical surface portion 24.
- the ring-shaped flat portions 25a and 25b are orthogonal to the central axis.
- the inner wheel element 15a includes an inner diameter side annular portion 28 and an outer diameter side annular portion 29 that are arranged concentrically with each other, and an outer peripheral surface of the inner diameter side annular portion 28.
- An annular connecting portion 30 that connects axially intermediate portions with the inner peripheral surface of the outer diameter side annular portion 29 is provided.
- the outer peripheral surface of the outer diameter side annular portion 29 is a cylindrical surface portion 24, and both axial side surfaces of the outer diameter side annular portion 29 are flat portions 25a and 25b.
- a portion surrounded on three sides by one axial end portion of the outer peripheral surface of the inner diameter side annular portion 28, one axial end portion of the inner peripheral surface of the outer diameter side annular portion 29, and one axial side surface of the connecting portion 30 is first. It is an annular recess 22, the other axial end portion of the outer peripheral surface of the inner diameter side annular portion 28, the other axial end portion of the inner peripheral surface of the outer diameter side annular portion 29, and the other axial end surface of the connecting portion 30.
- the portion surrounded by the three sides is the second annular recess 38.
- one end portion in the axial direction is the uneven portion 23, and the other end portion in the axial direction is the outer diameter side inclined surface portion 39 and the outer diameter side cylindrical surface portion 40.
- one axial end portion is a cylindrical surface portion 36, and the other axial end portion is an inner diameter side inclined surface portion 41.
- various metals such as copper alloys, aluminum alloys, magnesium alloys other than iron alloys, such as steel, can be employ
- various cutting processes and plastic processes can be employed as a process for forming the inner wheel element 15a. However, it is preferable to employ plastic working (forging, pressing, flow forming, etc.) in order to form with good yield and low cost.
- the outer wheel element 16a is made by injection molding of a synthetic resin. Along with this injection molding (by insert molding), a part of the inner wheel element 15a is embedded over the entire circumference. Yes. Specifically, the outer wheel element 16a has an outer peripheral surface (cylindrical surface) of the inner wheel element 15a from an inner diameter side peripheral surface (cylindrical surface part 36) constituting the inner surface of the first annular recess 22 in the surface of the inner wheel element 15a. A part of the inner wheel element 15a (a part of the inner wheel element 15a is covered so as to cover the entire circumference extending from the surface portion 24) to the inner diameter side peripheral surface (inner diameter side inclined surface portion 41) constituting the inner surface of the second annular recess 38.
- a part of the synthetic resin enters each of the first annular recess 22 and the second annular recess 38, and the part that enters the first annular recess 22 constitutes the annular first holding portion 31.
- the portion that has entered the second annular recess 38 constitutes an annular second holding portion 42.
- a part of the synthetic resin constituting the first restraining portion 31 includes a plurality of concave portions 26 and 26 (a portion between the convex portions 27 and 27 adjacent to each other in the circumferential direction) constituting the concave and convex portion 23.
- the rotation holding portion 32 is configured to engage with the concavo-convex portion 23 (having a shape that matches the concavo-convex portion 23) by covering the entire surface of the concavo-convex portion 23.
- the thickness of the first restraining portion 31 (excluding the thickness of the portions entering the plurality of recesses 26, 26) is substantially equal overall, and the thickness of the second restraining portion 42 is also overall. Is almost equal to Further, on the other side surface in the axial direction of the outer wheel element 16a, the same position in the radial direction as the radially inner end portion of the second annular recess 38 extends over the entire circumference, and the inner side of the second annular recess 38 (second restraining portion 42).
- the projecting portion 43 is provided so as to project from the other side surface in the axial direction to the other side in the axial direction.
- a worm wheel tooth portion 19a is formed on the outer peripheral surface of the outer wheel element 16a.
- the intermediate portion in the axial direction of the worm wheel tooth portion 19a overlaps the cylindrical surface portion 24 in the radial direction.
- the formation direction of the plurality of teeth constituting the worm wheel tooth portion 19a is inclined with respect to the axial direction of the worm wheel 4a.
- the diameter of the tip circle and the diameter of the root circle of the worm wheel tooth portion 19a are not changed with respect to the axial direction.
- the radially outer end portion (outer peripheral portion) of the disk gate 47 is located in a portion of the cavity 45 where the radially inner end portion (the overhang portion 43) on the other axial side of the outer wheel element 16a is formed.
- the runner 46 is provided so as to extend from the center of the disk gate 47 to the other side in the axial direction.
- the molten resin fed into the cavity 45 from the runner 46 and the disk gate 47 as described above flows from the inner diameter side to the outer diameter side along the other axial side surface of the inner wheel element 15a, and a part thereof is the second annular recess. 38.
- the inner diameter side inclined surface portion 41 and the outer diameter side inclined surface portion 39 are provided on the inner diameter side peripheral surface and the outer diameter side peripheral surface constituting the inner surface of the second annular recess 38. Therefore, the molten resin enters the portion of the cavity 45 where the radially outer end of the outer wheel element 16a is formed without greatly disturbing the flow. Further, the molten resin fed into the cavity 45 reaches a portion corresponding to the first restraining portion 31 and stops. In this part, there is no contact with the molten resin flowing from the other direction. As a result, it is possible to prevent the outer wheel element 16a obtained by injection molding from being weak in strength and causing welds or the like.
- the synthetic resin cooled and solidified in the cavity 45 corresponds to the radially inner end on the other axial side of the outer wheel element 16a after the mold device 44 is opened and the molds are separated from each other.
- the worm wheel 4a can be obtained by cutting along the entire circumference at a portion and finishing as necessary.
- a portion of the synthetic resin located at the radially outer end portion of the disk gate 47 (a portion that should be excised) is left without being cut, so that the overhang portion 43 is formed.
- the yield is improved and the overhanging portion 43 can be formed at a low cost.
- Synthetic resins constituting the outer wheel element 16a include polyamide 66 (PA66), polyamide 46 (PA46), polyamide 9T (PA9T), polyphenylene sulfide (PPS), polyethylene terephthalate (PET), polyacetal (POM).
- PA66 polyamide 66
- PA46 polyamide 46
- PA9T polyamide 9T
- PPS polyphenylene sulfide
- PET polyethylene terephthalate
- POM polyacetal
- Various synthetic resins such as can be employed. These synthetic resins can be mixed with various reinforcing fibers such as glass fibers, polyethylene fibers, carbon fibers, and aramid fibers, if necessary.
- the structure which overlaps with the cylindrical surface part 24 which exists in the outer peripheral surface of the inner side wheel element 15a in radial direction is employ
- a configuration is adopted in which the entire meshing portion 50 is superimposed on the cylindrical surface portion 24 in the radial direction.
- the axial width dimension S of the meshing part 50 is set to ⁇ S ⁇ T (S ⁇ T in the example shown in FIG.
- the positioned axial range is stored in the axial range where the cylindrical surface portion 24 is positioned.
- the axial width dimension S of the meshing portion 50 is made larger than the axial width dimension T of the cylindrical surface portion 24 (S> T), and the cylindrical surface portion 24 It is also possible to adopt a configuration in which the axial range that is positioned is within the axial range where the meshing portion 50 is positioned.
- the other axial side surface of the outer wheel element 16a constitutes a rolling bearing 8a installed in a portion adjacent to the other axial side of the worm wheel 4a.
- the inner ring 33a is opposed to one axial side surface of the inner ring 33a and the outer circumferential ring 34a in the axial direction with a gap therebetween.
- the portion corresponding to the overhanging portion 43 is opposed to the one side surface in the axial direction of the inner ring 33a in the axial direction, and is intermediate in the radial direction of the second holding portion 42.
- a portion corresponding to the portion is opposed to one axial side surface of the outer ring 34a in the axial direction.
- the one side surface in the axial direction of the inner ring 33a and the one side surface in the axial direction of the outer ring 34a exist at substantially the same position in the axial direction, whereas the other side in the axial direction of the outer wheel element 16a.
- the portion corresponding to the overhang portion 43 is the portion corresponding to the radial intermediate portion of the second holding portion 42 (the radial intermediate portion of the second holding portion 42). Is located on the other side in the axial direction (at least by the axial dimension of the overhang portion 43).
- the axial distance X between the other axial side surface of the outer wheel element 16a (the other axial side surface of the overhang portion 43) and the one axial side surface of the inner ring 33a is the other axial side surface of the outer wheel element 16a. It is smaller than the axial distance Y (X ⁇ Y) between the other axial side surface of the second intermediate portion 42 in the radial direction and the one axial side surface of the outer ring 34a.
- the outer wheel element 16a of the outer wheel element 16a is secured while securing the holding force of the outer wheel element 16a made of synthetic resin to the metal inner wheel element 15a. Manufacturing errors of the worm wheel tooth portion 19a provided on the outer peripheral surface can be suppressed. This point will be described below.
- the first annular recess 22 and the second annular recess 38 are provided on both sides in the axial direction of the inner wheel element 15a over the entire circumference.
- the outer side wheel element 16a is the outer peripheral surface (cylindrical surface part 24) of the inner side wheel element 15a from the internal diameter side peripheral surface (cylindrical surface part 36) which comprises the inner surface of the 1st annular recessed part 22 among the surfaces of the inner side wheel element 15a. Then, a part of the inner wheel element 15a is embedded so as to cover a continuous range up to the inner diameter side peripheral surface (inner diameter side inclined surface portion 41) constituting the inner surface of the second annular recess 38 over the entire circumference. ing.
- the outer wheel element 16a embeds not only the radially outer end portion but also the radially intermediate portion of the inner wheel element 15a. For this reason, the holding force in the moment M direction of the outer wheel element 16a with respect to the inner wheel element 15a can be increased as compared with the case where only the radially outer end portion is embedded.
- a part of the synthetic resin constituting the outer wheel element 16a enters the first annular recess 22 to form the annular first holding portion 31 and the second annular recess 38.
- An annular second holding portion 42 is formed by entering. For this reason, based on the engagement between the first annular recess 22 and the first restraining portion 31 and the engagement between the second annular recess 38 and the second restraining portion 42, the outer wheel element 16a with respect to the inner wheel element 15a.
- the holding force in the moment M direction can be increased.
- the outer diameter side cylindrical surface portion 40 is provided at the other axial end portion of the outer diameter side peripheral surface constituting the inner surface of the second annular recess 38. Therefore, as compared with the case where the entire outer diameter side peripheral surface is the outer diameter side inclined surface portion 39 (the outer diameter side cylindrical surface portion 40 is not provided), The engagement force with the second restraining portion 42 can be increased. As a result, the holding force in the moment M direction of the outer wheel element 16a with respect to the inner wheel element 15a can be increased.
- the concave and convex portions 23 in the circumferential direction are provided on the outer peripheral side peripheral surface constituting the inner surface of the first annular recess 22, and the synthetic resin constituting the first restraining portion 31.
- the rotation holding part 32 is configured. For this reason, in the case of this embodiment, the holding force of the rotation direction of the outer wheel element 16a with respect to the inner wheel element 15a is securable.
- the uneven portion 23 is provided over the entire length in the axial direction of the outer peripheral side peripheral surface constituting the inner surface of the first annular recess 22, so that the holding force in the rotational direction is increased. Can be bigger.
- the outer peripheral surface of the inner wheel element 15a is a cylindrical surface portion 24 whose diameter does not change in the axial direction.
- the radial thickness of the portion of the outer wheel element 16a that overlaps the radially outer side with respect to the cylindrical surface portion 24, which is the outer peripheral surface of the inner wheel element 15a is a plurality of the worm wheel tooth portions 19a.
- the portions where the teeth 20a, 20a are located are substantially (substantially) equal to each other.
- both end edges in the axial direction of the cylindrical surface portion 24 that is the outer peripheral surface of the inner wheel element 15a have a circular shape in which the axial position does not change with respect to the circumferential direction.
- the radial thickness of the portion of the outer wheel element 16a that overlaps the outer peripheral surface of the inner wheel element 15a in the radial direction includes the edges at both ends in the axial direction.
- the portions where the plurality of teeth 20a, 20a constituting the worm wheel tooth portion 19a are located are substantially equal to each other.
- the injection molding of the portion where the plurality of teeth 20a, 20a are located As shown in FIG. 6, the injection molding of the portion where the plurality of teeth 20a, 20a are located.
- the molding shrinkage at the time can be made almost equal to each other.
- the size (diameter thickness) of the plurality of teeth 20a, 20a after molding can be made substantially equal, and as a result, manufacturing errors such as pitch errors related to the worm wheel tooth portion 19a can be reduced. It can be suppressed.
- the plurality of concave portions 26 and convex portions 27 constituting the concave and convex portion 23 are formed in parallel to the axial direction. For this reason, the deformation of the outer wheel element 16a due to the molding shrinkage of the synthetic resin caused by the presence of the uneven portion 23 can be suppressed, and the outer wheel element 16a can be molded with high accuracy.
- the entire meshing portion 50 of the worm tooth portion 18 and the worm wheel tooth portion 19a is superimposed on the cylindrical surface portion 24 in the radial direction in a state where the worm speed reducer is assembled.
- the worm tooth portion 18 is meshed with the portion of the worm wheel tooth portion 19a in which the manufacturing error such as the pitch error is suppressed as described above.
- the meshing state of the meshing part 50 can be made favorable.
- the meshing state of the meshing part increases as the overlapping ratio (axial range) increases. Will be better.
- the axial width dimension S of the engaging portion 50 is set to be equal to or smaller than the axial width dimension T of the cylindrical surface portion 24 (S ⁇ T) in order to overlap the entire engaging portion 50 with the cylindrical surface portion 24 in the radial direction. If these dimensions S and T are made substantially equal under these conditions, the meshing state of the meshing portion 50 can be improved while the axial dimension of the inner wheel element 15a is minimized. it can. Note that the same applies to the case where the condition of S> T is adopted.
- the axial distance X between the other axial side surface of the outer wheel element 16a (the other axial side surface of the overhang portion 43) and the one axial side surface of the inner ring 33a is the other axial direction side surface of the outer wheel element 16a ( It is smaller than the axial distance Y between the other axial side surface of the second intermediate portion 42 in the radial direction and the one axial side surface of the outer ring 34a (X ⁇ Y).
- the axial direction of the outer wheel element 16a is in contact with only one side surface in the axial direction of the inner ring 33a among the one side surface in the axial direction of the inner ring 33a and one side surface in the axial direction of the outer ring 34a (the other side surface in the axial direction of the protruding portion 43). Since one side surface in the direction (the other axial side surface of the intermediate portion in the radial direction of the second holding portion 42) does not contact, the rotation of the worm wheel 4a can be prevented from being locked.
- the configuration of the second annular recess 38a provided on the other axial side surface (the right side surface in FIG. 8) of the inner wheel element 15b constituting the worm wheel 4b is the first embodiment described above.
- the inner peripheral side peripheral surface constituting the inner surface of the second annular recess 38a is provided in the half portion on one axial side (left side in FIG. 8), and is not inclined according to the claims.
- the axial end edges of the inner diameter side cylindrical surface portion 48 corresponding to the surface portion and the inner diameter side inclined surface portion 41 provided on the other half in the axial direction are made continuous.
- the inner diameter side cylindrical surface portion 48 is provided on one half of the axial direction of the inner diameter side peripheral surface constituting the inner surface of the second annular recess 38a.
- the second annular recess 38a and the outer wheel element 16b with respect to the moment M are configured.
- the engagement force with the second restraining portion 42a can be increased.
- the holding force in the moment M direction of the outer wheel element 16b with respect to the inner wheel element 15b can be increased.
- Other configurations and operations are the same as those of the first embodiment described above.
- the configuration of the second annular recess 38b provided on the other axial side surface (the right side surface in FIG. 9) of the inner wheel element 15c constituting the worm wheel 4c is the first embodiment described above.
- the inner diameter side peripheral surface constituting the inner surface of the second annular recess 38b includes an inner diameter side inclined surface portion 41 provided on a half portion on one axial side (the left side in FIG. 9), and other axial directions.
- the inner diameter side cylindrical surface portion 48a is provided in the other half portion in the axial direction of the inner diameter side peripheral surface constituting the inner surface of the second annular recess 38b.
- the second annular recess 38b and the outer wheel element 16c with respect to the moment M are configured. Engagement force with the 2nd holding
- Other configurations and operations are the same as those of the first embodiment described above.
- FIG. 10 A fourth embodiment of the present invention will be described with reference to FIG.
- the configuration of the first annular recess 22a provided on one axial side surface (the left side surface in FIG. 10) of the inner wheel element 15d constituting the worm wheel 4d is the first embodiment described above. Different from the case of form.
- the plurality of recesses 26a and protrusions 27a that constitute the recesses and protrusions 23a provided on the outer diameter side peripheral surface are relative to the central axis of the worm wheel 4d.
- the plurality of teeth 20a, 20a constituting the worm wheel tooth portion 19a provided on the outer peripheral surface of the outer wheel element 16d are inclined in the direction opposite to the inclination direction.
- Other configurations and operations are the same as those of the first embodiment described above.
- FIG. 1 A sixth embodiment of the present invention will be described with reference to FIG.
- the present embodiment is a modification of the first embodiment shown in FIGS. 1 to 7 described above.
- the axial dimensions of both side portions sandwiching the central position Ca of the inner wheel element 15f with respect to the direction are equal to each other (L A or L B ).
- a portion (including the worm wheel tooth portion 19a) positioned radially outward from the inner wheel element 15f and the inner wheel element of the outer wheel element 16f. 15f of portions (outer-diameter side annular portion 29) that overlap in the axial direction with respect to the portion (outer-diameter-side annular portion 29) positioned radially outward from both first and second annular recesses 22 and 38 And the axial dimensions of both side portions sandwiching the center position Ca in the axial direction are equal to each other (L C or L D ).
- FIGS. 1 to 7 A seventh embodiment of the present invention will be described with reference to FIGS. This embodiment is a modification of the first embodiment shown in FIGS. 1 to 7 described above.
- the surface of the cylindrical surface portion 24a provided on the outer peripheral surface of the inner wheel element 15g constituting the worm wheel 4g is a knurled surface 57 that is a fine uneven surface formed by knurling.
- a knurled surface 57 a flat surface in which the unevenness forming direction is parallel to the axial direction as shown in the upper half of FIG.
- a twill that has an uneven formation direction inclined with respect to the axial direction and intersecting, as shown in the upper half of FIG. 14B, for example. .
- the radial depths W 58a and W 58b of the minute recesses 58a and 58b constituting the knurled surface 57 are the worm wheel teeth provided on the outer peripheral surface of the outer wheel element 16g. It has become radial height dimension of each tooth 20a (tooth depth) 1/10 of H 20a (W 58a ⁇ H 20a / 10, W 58b ⁇ H 20a / 10) constituting a part 19a.
- a part of the synthetic resin constituting the outer wheel element 16g is made to enter the minute recesses 58a and 58b constituting the knurled surface 57.
- the inner wheel is based on the engagement between a part of the synthetic resin constituting the outer wheel element 16g and the minute recesses 58a and 58b constituting the knurled surface 57.
- the holding force in the rotation direction of the outer wheel element 16g with respect to the element 15g can be increased.
- the inner wheel is based on the engagement between a part of the synthetic resin constituting the outer wheel element 16g and the minute recesses 58a, 58b constituting the knurled surface 57.
- the holding force in the rotation direction of the outer wheel element 16g with respect to the element 15g but also the holding force in the moment M direction can be increased.
- the knurled surface 57 has a fine uneven shape (W 58a ⁇ H 20a / 10, W 58b ⁇ H 20a / 10), so that the minute concave portions 58a and 58b constituting the knurled surface 57 are provided. Even if a part of the synthetic resin constituting the outer wheel element 16g enters, the volume of the entire synthetic resin is hardly affected. For this reason, also in the case of the present embodiment, the radial thickness of the portion of the outer wheel element 16g that overlaps the outer side in the radial direction with respect to the knurled surface 57 is determined by the plurality of teeth 20a constituting the worm wheel tooth portion 19a.
- each tooth 20a, 20a can be made substantially (substantially) equal to each other. Therefore, also in the case of this embodiment, the amount of molding shrinkage of each tooth 20a, 20a when the outer wheel element 16g is injection-molded can be made substantially equal to each other, which is related to the worm wheel tooth portion 19a. Manufacturing errors such as pitch errors can be suppressed.
- Other configurations and operations are the same as those of the first embodiment described above.
- FIG. 8 An eighth embodiment of the present invention will be described with reference to FIG. This embodiment is a modification of the first embodiment shown in FIGS. 1 to 7 described above.
- the cylindrical surface portion 24 is provided only at the axially intermediate portion of the outer peripheral surface of the inner wheel element 15h constituting the worm wheel 4h, and the worm tooth portion 18 and the worm wheel tooth portion 19a.
- a configuration is adopted in which the entire meshing portion 50 overlaps with the cylindrical surface portion 24 in the radial direction.
- the concave portion 26b and the convex portion are formed on the radially outer end portions (the portions located radially outside the first and second annular concave portions 22 and 38) on both axial sides of the inner wheel element 15h.
- Concave and convex portions 23b formed by alternately arranging the portions 27b in the circumferential direction are provided.
- the uneven portion 23 b is provided in the axial range adjacent to both sides in the axial direction of the cylindrical surface portion 24.
- the outer wheel with respect to the inner wheel element 15h is made to enter a part of the synthetic resin that constitutes the outer wheel element 16h inside each concave part 26b that constitutes the uneven parts 23b and 23b. The holding force in the rotation direction of the element 16h is increased.
- the entire meshing portion 50 overlaps the cylindrical surface portion 24 in the radial direction, the axial range where the meshing portion 50 is located (the axis where the cylindrical surface portion 24 is located). In the direction range), manufacturing errors such as pitch errors related to the worm wheel tooth portion 19a can be suppressed. Therefore, the meshing state of the meshing part 50 can be improved.
- the concave and convex portion 23 (see FIGS. 2 to 3) is not provided on the outer peripheral side circumferential surface constituting the inner surface of the first annular concave portion 22, but when the present invention is implemented, the concave and convex portion is provided. 23 can also be provided (for example, in a state of being continuous with the uneven portion 23b on one axial side). Other configurations and operations are the same as those of the first embodiment described above.
- FIGS. 1 to 7 A ninth embodiment of the present invention will be described with reference to FIGS. This embodiment is a modification of the first embodiment shown in FIGS. 1 to 7 described above.
- a sub-recess 59 is provided in the axially inner end (the other end in the axial direction, the right end in FIGS. 18 to 19) that is recessed radially outward over the entire circumference.
- the cross-sectional shape of the sub-recess 59 relating to the virtual plane including the central axis of the inner wheel element 15i is a V-shape whose width dimension in the axial direction decreases from the opening on the inner diameter side toward the bottom on the outer diameter side. .
- the uneven portion 23 is provided on the entire portion of the outer peripheral side peripheral surface constituting the inner surface of the first annular recess 22 that is separated from the sub-recess 59. Then, the axially inner end portions of the concave portions 26 constituting the concave and convex portions 23 are opened on the inner surfaces of the sub concave portions 59, respectively.
- the radial depth of the sub-recess portion 59 is slightly larger than the radial depth of each recess portion 26 constituting the uneven portion 23.
- the radial depth of the sub-recesses 59 is equal to the radial depth of the respective recesses 26 or smaller than the radial depth of each of the recesses 26. .
- a part of the synthetic resin constituting the outer wheel element 16 i that has entered the first annular recess 22 is part of the sub-recess 59.
- the sub-repression portion 60 that engages with the sub-recess 59 is formed.
- the holding force in the direction of the moment M of the outer wheel element 16i with respect to the inner wheel element 15i is improved based on the engagement between the sub recessed portion 59 and the sub restraining portion 60. Can do.
- the cross-sectional shape of the sub-recess 59 is a V-shape whose width dimension in the axial direction decreases from the opening on the inner diameter side toward the bottom on the outer diameter side. The molten resin can smoothly enter from the opening 59 to the bottom. Therefore, the flow of the molten resin in the cavity 45 can be prevented from being obstructed, and the moldability of the auxiliary restraining portion 60 can be improved.
- the sub-recessed portion 59 is formed on the outer peripheral side peripheral surface constituting the inner surface of the first annular recessed portion 22, and then the uneven portion 23 is formed.
- the sub-recess 59 is used as a relief of the molding die for the uneven portion 23 or a relief portion of the metal material deformed as the uneven portion 23 is formed. it can.
- the molding load of the concavo-convex portion 23 can be kept low, the molding equipment capacity of the concavo-convex portion 23 can be reduced, and the life of the molding die can be improved.
- the sub-recess 59 can be formed by cutting or the like after the uneven portion 23 is formed. Other configurations and operations are the same as those of the first embodiment described above.
- the inner wheel element is made of metal.
- the inner wheel element is synthesized with better heat resistance than the synthetic resin constituting the outer wheel element. It can also be made of resin. Even in this case, the same effects as those in the above-described embodiments can be obtained.
- the surface of the inner wheel element covered with the synthetic resin constituting the outer wheel element for example, a cylindrical surface part, the entire surface of the inner wheel element.
- the portion removed from the knurled surface 57 is a fine uneven surface formed by various processes such as knurling, embossing, and shot blasting, this minute Since a part of the synthetic resin that constitutes the outer wheel element enters the recess that constitutes the uneven surface, the holding power (adhesion) of the outer wheel element with respect to the inner wheel element can be increased.
- the depth of the concave portion constituting the fine uneven surface is set to 1/10 or less (for example, 1/20 or less) of the radial height of the teeth constituting the worm wheel tooth portion. 1/30 or less), if the volume of the synthetic resin constituting the outer wheel element is not significantly affected, the manufacturing error of the portion of the worm wheel tooth portion that meshes with the worm tooth portion can be suppressed.
- the worm wheel and the worm speed reducer of the present invention can be used by being incorporated in various mechanical devices such as a wiper device as well as an electric power steering device.
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Abstract
Description
前記内側ホイール素子は、軸方向片側面に軸方向に凹む状態で設けられた第一環状凹部を有している。
又、前記外側ホイール素子は、合成樹脂製で、外周面にウォームホイール歯部を有し、前記内側ホイール素子の表面のうち、前記第一環状凹部の内面を構成する内径側周面から、前記内側ホイール素子の外周面を経て、前記内側ホイール素子の軸方向他側面の径方向内端寄り部分(径方向中央位置よりも径方向内側に位置する部分)に至るまでの連続した範囲を全周に亙り覆う様に、前記内側ホイール素子を包埋している。
この場合には、例えば、前記凹凸部が、前記第一環状凹部や前記第二環状凹部の内面を構成する外径側周面や内径側周面に設けられている構成を採用する事ができる。
この場合には、例えば、前記凹凸部が前記第一環状凹部や前記第二環状凹部の内面を構成する外径側周面や内径側周面の軸方向全長に亙り設けられており、前記外側ホイール素子を構成する合成樹脂の一部が前記凹凸部を構成する凹部の全体に入り込んでいる構成を採用する事ができる。
又は、前記ウォームホイール歯部を構成する複数の歯が、前記ウォームホイールの軸方向に対して所定方向に傾斜した方向に形成されていると共に、前記凹凸部を構成する複数ずつの凹部及び凸部が、前記ウォームホイールの軸方向に対して前記所定方向と反対方向に傾斜した方向に形成されている構成を採用する事ができる。
この場合には、例えば、前記内側ホイール素子の中心軸を含む仮想平面に関する前記副凹部の断面形状が、内径側の開口部から外径側の底部に向かうに従って軸方向に関する幅寸法が小さくなるV字形になっている構成を採用する事ができる。
この様な構成を採用すれば、前記微細な凹凸面を構成する凹部に前記外側ホイール素子を構成する合成樹脂の一部が入り込む為、前記内側ホイール素子に対する前記外側ホイール素子の保持力(密着性)を高める事ができる。
尚、前記微細な凹凸面を構成する凹部の深さは、前記ウォームホイール歯部を構成する歯の径方向高さの1/10以下(好ましくは1/20以下、より好ましくは1/30以下)として、前記外側ホイール素子を構成する合成樹脂の体積に余り影響を与えない様にするのが好ましい。
回転軸は、前記ハウジングに対し回転自在に支持されている。
又、前記ウォームホイールは、外周面にウォームホイール歯部を有し、前記回転軸に外嵌固定されている。
又、前記ウォーム軸は、外周面の軸方向中間部にウォーム歯部を有し、前記ウォーム歯部を前記ウォームホイール歯部に噛合させた状態で、前記ハウジングに対し回転自在に支持されている。
特に、本発明のウォーム減速機の場合には、前記ウォームホイールが、本発明のウォームホイールである。
この場合には、例えば、前記内側ホイール素子の外周面のうちで、前記噛合部の全体と径方向に重畳する軸方向範囲が前記円筒面部になっている構成を採用する事ができる。
又、これらの場合には、例えば、前記内側ホイール素子の外周面の全体(この外周面の軸方向端縁部に面取り部が設けられる場合には、この面取り部を除く)が前記円筒面部になっている構成を採用する事ができる。
又、前記ウォームホイールを構成する前記外側ホイール素子の軸方向他側面を、前記内輪の軸方向片側面及び前記外輪の軸方向片側面と軸方向に対向させる事ができる。
又、前記外側ホイール素子の軸方向他側面と前記内輪の軸方向片側面との間の軸方向距離を、前記外側ホイール素子の軸方向他側面と前記外輪の軸方向片側面との間の軸方向距離よりも小さくする事ができる。
別な言い方をすれば、前記外側ホイール素子の軸方向他側面のうち、前記内輪の軸方向片側面と軸方向に対向する部分に、前記外輪の軸方向片側面と軸方向に対向する部分よりも軸方向他側に張り出した張出部を設ける事ができる。
この様な本発明のウォームホイールの製造方法は、前記外側ホイール素子を射出成形により造るのと同時に、前記外側ホイール素子を前記内側ホイール素子に対して結合する、インサート成形を実施する際に、前記外側ホイール素子の軸方向他側の径方向内端部に、ディスクゲートの径方向外端部を位置させる事を特徴とする。
本発明の第1実施形態に就いて、図1~7により説明する。
図1は、本実施形態のウォーム減速機を組み込んだ電動式パワーステアリング装置を示している。後端部にステアリングホイール1(図20参照)が取り付けられたステアリングシャフト2の前端部は、ハウジング3内に回転自在に支持されている。ステアリングシャフト2により回転駆動される部分には、ウォームホイール4aが固定されている。一方、電動モータ5の出力軸にはウォーム軸6(図3及び図21参照)が連結されている。そして、ウォーム軸6の軸方向中間部外周面に設けられたウォーム歯部18と、ウォームホイール4aの外周面に設けられたウォームホイール歯部19aとを噛合させる事により、電動モータ5からウォームホイール4aに対して、所定方向に所定の大きさの補助トルク(補助動力)を付与する事が可能となっている。
内側ホイール素子15aは、金属により円環状(略円輪状)に造られたもので、径方向中央部に、出力軸7の軸方向中間部をトルク伝達を可能に内嵌固定する為の嵌合孔21を有している。
第一環状凹部22の内面を構成する内径側周面と外径側周面と底面(軸方向片側面)とのうち、外径側周面には、この外径側周面の軸方向の全長及び全周に亙り、円周方向に関して凹部26と凸部27とを交互に(図示の例では等ピッチに)配置して成る、円周方向に関する(歯車状の)凹凸部23が設けられている。本実施形態の場合、凹凸部23を構成する複数ずつの凹部26及び凸部27は、図4に於ける上半部に破線(隠れ線)で示す様に、内側ホイール素子15a(ウォームホイール4a)の軸方向(図1~4及び図7に於ける左右方向)に対して平行に形成されている。別な言い方をすれば、凹部26と凸部27との境界は、ウォームホイール4aの軸方向に対して平行になっている。
又、第一環状凹部22の内面を構成する内径側周面は、単なる円筒面状の円筒面部36になっている。
又、第一環状凹部22の内面を構成する底面は、内側ホイール素子15aの中心軸に対して直交する円輪状の中間平面部37aになっている。
第二環状凹部38の内面を構成する内径側周面と外径側周面と底面(軸方向他側面)とのうち、外径側周面は、軸方向に関して、片側(片端部及び中間部)に設けられた外径側傾斜面部39と、他側(他端部)に設けられた外径側円筒面部40との、互いの軸方向端縁同士を連続させて成る。外径側傾斜面部39は、特許請求の範囲に記載した傾斜面部に相当する部位であり、内側ホイール素子15aの中心軸に対し、軸方向他側に向かうに従って第二環状凹部38の径方向に関する幅寸法が大きくなる方向(径方向外側に向かう方向)に傾斜した、部分円すい面状に形成されている。これに対し、外径側円筒面部40は、特許請求の範囲に記載した非傾斜面部に相当する部位であり、内側ホイール素子15aの中心軸に対して傾斜しない、単なる円筒面状に形成されている。
又、第二環状凹部38の内面を構成する内径側周面は、内径側傾斜面部41のみから成る。内径側傾斜面部41は、特許請求の範囲に記載した傾斜面部に相当する部位であり、内側ホイール素子15aの中心軸に対し、軸方向他側に向かうに従って第二環状凹部38の径方向に関する幅寸法が大きくなる方向(径方向内側に向かう方向)に傾斜した、部分円すい面状に形成されている。
又、第二環状凹部38の内面を構成する底面は、内側ホイール素子15aの中心軸に対して直交する円輪状の中間平面部37bになっている。
特に、本実施形態の場合には、噛合部50の全体が、円筒面部24と径方向に重畳する構成を採用している。この為に、噛合部50の軸方向幅寸法Sを、円筒面部24の軸方向幅寸法T以下{S≦T(図3に示した例ではS<T)}にすると共に、噛合部50の位置する軸方向範囲を、円筒面部24の位置する軸方向範囲内に収めている。
但し、本発明を実施する場合には、例えば、噛合部50の軸方向幅寸法Sを、円筒面部24の軸方向幅寸法Tよりも大きくする(S>Tにする)と共に、円筒面部24の位置する軸方向範囲を、噛合部50の位置する軸方向範囲内に収める構成を採用する事もできる。
本発明の第2実施形態に就いて、図8により説明する。
本実施形態の場合には、ウォームホイール4bを構成する内側ホイール素子15bの軸方向他側面(図8に於ける右側面)に設けられた第二環状凹部38aの構成が、上述した第1実施形態の場合と異なる。本実施形態の場合、第二環状凹部38aの内面を構成する内径側周面は、軸方向片側(図8に於ける左側)の半部に設けられた、特許請求の範囲に記載した非傾斜面部に対応する内径側円筒面部48と、軸方向他側の半部に設けられた内径側傾斜面部41との、互いの軸方向端縁同士を連続させて成る。
その他の構成及び作用は、上述した第1実施形態の場合と同様である。
本発明の第3実施形態に就いて、図9により説明する。
本実施形態の場合には、ウォームホイール4cを構成する内側ホイール素子15cの軸方向他側面(図9に於ける右側面)に設けられた第二環状凹部38bの構成が、上述した第1実施形態の場合と異なる。本実施形態の場合、第二環状凹部38bの内面を構成する内径側周面は、軸方向片側(図9に於ける左側)の半部に設けられた内径側傾斜面部41と、軸方向他側の半部に設けられた、特許請求の範囲に記載した非傾斜面部に対応する内径側円筒面部48aとを、軸方向他側を向いた円輪状の段差面49により連続させて成る。
その他の構成及び作用は、上述した第1実施形態の場合と同様である。
本発明の第4実施形態に就いて、図10により説明する。
本実施形態の場合には、ウォームホイール4dを構成する内側ホイール素子15dの軸方向片側面(図10に於ける左側面)に設けられた第一環状凹部22aの構成が、上述した第1実施形態の場合と異なる。本実施形態の場合、第一環状凹部22aの内面のうち、外径側周面に設けられた凹凸部23aを構成する複数ずつの凹部26a及び凸部27aは、ウォームホイール4dの中心軸に対し、外側ホイール素子16dの外周面に設けられたウォームホイール歯部19aを構成する複数の歯20a、20aの傾斜方向と逆方向に傾斜した状態で形成されている。
その他の構成及び作用は、上述した第1実施形態の場合と同様である。
本発明の第5実施形態に就いて、図11により説明する。本実施形態の場合は、上述の図8に示した第2実施形態の変形例である。
その他の構成及び作用は、上述した第2実施形態の場合と同様である。
本発明の第6実施形態に就いて、図12により説明する。本実施形態の場合は、上述の図1~7に示した第1実施形態の変形例である。
その他の構成及び作用は、上述した第1実施形態の場合と同様である。
本発明の第7実施形態に就いて、図13~16により説明する。本実施形態は、上述の図1~7に示した第1実施形態の変形例である。
その他の構成及び作用は、上述した第1実施形態の場合と同様である。
本発明の第8実施形態に就いて、図17により説明する。本実施形態は、上述の図1~7に示した第1実施形態の変形例である。
その他の構成及び作用は、上述した第1実施形態の場合と同様である。
本発明の第9実施形態に就いて、図18~19により説明する。本実施形態は、上述の図1~7に示した第1実施形態の変形例である。
その他の構成及び作用は、上述した第1実施形態の場合と同様である。
2 ステアリングシャフト
3 ハウジング
4、4a~4i ウォームホイール
5 電動モータ
6 ウォーム軸
7 出力軸
8a、8b 転がり軸受
9 トーションバー
10 トルクセンサ
11a、11b 自在継手
12 中間シャフト
13 ステアリングギヤユニット
14 ピニオン軸
15、15a~15i 内側ホイール素子
16、16a~16i 外側ホイール素子
17 凹凸部
18 ウォーム歯部
19、19a ウォームホイール歯部
20、20a 歯
21 嵌合孔
22、22a、22b 第一環状凹部
23、23a、23b 凹凸部
24、24a 円筒面部
25a、25b 平面部
26、26a 凹部
27、27a 凸部
28 内径側環状部
29 外径側環状部
30 連結部
31 第一抑え部
32 回転保持部
33a、33b 内輪
34a、34b 外輪
35a、35b 玉
36 円筒面部
37a、37b 中間平面部
38、38a~38c 第二環状凹部
39 外径側傾斜面部
40 外径側円筒面部
41 内径側傾斜面部
42、42a、42b 第二抑え部
43 張出部
44 金型装置
45 キャビティ
46 ランナー
47 ディスクゲート
48、48a 内径側円筒面部
49 段差面
50 噛合部
51 凹凸部
52 凹部
53 凸部
54 凹凸部
55 凹部
56 凸部
57 ローレット面
58a、58b 微小凹部
59 副凹部
60 副抑え部
Claims (21)
- 内側ホイール素子と、外側ホイール素子とを備え、
前記内側ホイール素子は、軸方向片側面に軸方向に凹む状態で設けられた第一環状凹部を有しており、
前記外側ホイール素子は、合成樹脂製で、外周面にウォームホイール歯部を有し、前記内側ホイール素子の表面のうち、前記第一環状凹部の内面を構成する内径側周面から、前記内側ホイール素子の外周面を経て、前記内側ホイール素子の軸方向他側面の径方向内端寄り部分に至るまでの連続した範囲を全周に亙り覆う様に、前記内側ホイール素子を包埋している
ウォームホイール。 - 前記内側ホイール素子の軸方向他側面に軸方向に凹む状態で第二環状凹部が設けられており、
前記外側ホイール素子は、前記内側ホイール素子の表面のうち、前記第一環状凹部の内面を構成する内径側周面から、前記内側ホイール素子の外周面を経て、前記第二環状凹部の内面を構成する内径側周面に至るまでの連続した範囲を全周に亙り覆う様に、前記内側ホイール素子を包埋している
請求項1に記載したウォームホイール。 - 前記第二環状凹部の内面を構成する外径側周面と内径側周面とのうち、少なくとも一方の周面に、前記内側ホイール素子の中心軸に対し、軸方向他側に向かうに従って前記第二環状凹部の径方向に関する幅寸法が大きくなる方向に傾斜した傾斜面部が設けられている
請求項2に記載したウォームホイール。 - 前記第二環状凹部の内面を構成する外径側周面には、前記傾斜面部と、前記内側ホイール素子の中心軸に対して傾斜しない非傾斜面部と、が設けられている
請求項3に記載したウォームホイール。 - 前記第二環状凹部の内面を構成する内径側周面には、前記傾斜面部と、前記内側ホイール素子の中心軸に対して傾斜しない非傾斜面部と、が設けられている
請求項3~4のうちの何れか1項に記載したウォームホイール。 - 前記内側ホイール素子では、前記第一環状凹部及び前記第二環状凹部よりも径方向外側に位置する部分と、前記第一環状凹部の底面と前記第二環状凹部の底面との間に挟まれた部分とは、それぞれ、軸方向に関して前記内側ホイール素子の中央位置を挟んだ両側部分の軸方向寸法が互いに等しくなっており、
前記外側ホイール素子では、前記内側ホイール素子よりも径方向外側に位置する部分と、前記内側ホイール素子のうちの前記第一環状凹部及び前記第二環状凹部よりも径方向外側に位置する部分に対して軸方向に重畳する部分とは、それぞれ、軸方向に関して前記内側ホイール素子の中央位置を挟んだ両側部分の軸方向寸法が互いに等しくなっている
請求項2~5のうちの何れか1項に記載したウォームホイール。 - 前記内側ホイール素子の表面に、円周方向に関する凹凸部が設けられており、
前記外側ホイール素子を構成する合成樹脂の一部が前記凹凸部を構成する凹部に入り込んでいる
請求項1~6のうちの何れか1項に記載したウォームホイール。 - 前記凹凸部が、前記第一環状凹部の内面に設けられている
請求項7に記載したウォームホイール。 - 前記内側ホイール素子の軸方向他側面に全周に亙り軸方向に凹む状態で第二環状凹部が設けられており、
前記凹凸部が、前記第二環状凹部の内面に設けられている
請求項7又は8に記載したウォームホイール。 - 前記第一環状凹部の内面を構成する外径側周面のうちで、前記第一環状凹部の軸方向開口側端縁よりも軸方向奥側に位置する部分に、径方向外方に凹む状態で副凹部が設けられており、
前記外側ホイール素子を構成する合成樹脂の一部が前記副凹部に入り込んでいる
請求項1~9のうちの何れか1項に記載したウォームホイール。 - 前記内側ホイール素子の中心軸を含む仮想平面に関する前記副凹部の断面形状が、内径側の開口部から外径側の底部に向かうに従って軸方向に関する幅寸法が小さくなるV字形になっている
請求項10に記載したウォームホイール。 - 前記内側ホイール素子は、外周面のうち少なくとも一部の軸方向範囲が円筒面部になっている
請求項1~11のうちの何れか1項に記載したウォームホイール。 - 前記内側ホイール素子の表面のうち、前記外側ホイール素子を構成する合成樹脂により覆われる部分のうちの少なくとも一部分が、微細な凹凸面になっている
請求項12に記載したウォームホイール。 - 前記外側ホイール素子の軸方向他側面の径方向内端部に、径方向外側に隣接する部分よりも軸方向他側に張り出した張出部が設けられている
請求項1~13のうちの何れか1項に記載したウォームホイール。 - ハウジングと、
前記ハウジングに対し回転自在に支持された回転軸と、
外周面にウォームホイール歯部を有し、前記回転軸に外嵌固定されたウォームホイールと、
外周面の軸方向中間部にウォーム歯部を有し、前記ウォーム歯部を前記ウォームホイール歯部に噛合させた状態で、前記ハウジングに対し回転自在に支持されたウォーム軸と、を備えたウォーム減速機であって、
前記ウォームホイールが請求項1~14のうちの何れか1項に記載したウォームホイールである事を特徴とするウォーム減速機。 - 前記ウォームホイールを構成する内側ホイール素子の外周面のうちで、前記ウォームホイール歯部と前記ウォーム歯部との噛合部のうちの少なくとも軸方向一部分と径方向に重畳する軸方向範囲が円筒面部になっている
請求項15に記載したウォーム減速機。 - 前記内側ホイール素子の外周面のうちで、前記噛合部の全体と径方向に重畳する軸方向範囲が前記円筒面部になっている
請求項16に記載したウォーム減速機。 - 前記内側ホイール素子の外周面の全体が前記円筒面部になっている
請求項16又は17に記載したウォーム減速機。 - 前記ウォームホイールの軸方向他側に隣り合う部分に、内輪と外輪と前記内輪の外周面と前記外輪の内周面との間に設けられた複数個の転動体とを備えた、前記回転軸を前記ハウジングに対して回転可能に支持する為の転がり軸受が設置されており、
前記ウォームホイールを構成する前記外側ホイール素子の軸方向他側面は、前記内輪の軸方向片側面及び前記外輪の軸方向片側面と軸方向に対向しており、
前記外側ホイール素子の軸方向他側面と前記内輪の軸方向片側面との間の軸方向距離が、前記外側ホイール素子の軸方向他側面と前記外輪の軸方向片側面との間の軸方向距離よりも小さくなっている
請求項15~18のうちの何れか1項に記載したウォーム減速機。 - 前記外側ホイール素子の軸方向他側面の径方向内端部に、径方向外側に隣接する部分よりも軸方向他側に張り出した張出部が設けられており、
前記張出部の軸方向他側面が、前記内輪の軸方向片側面と軸方向に対向している
請求項19に記載したウォーム減速機。 - 請求項1~14のうちの何れか1項に記載したウォームホイールの製造方法であって、
前記外側ホイール素子を射出成形により造るのと同時に、前記外側ホイール素子を前記内側ホイール素子に対して結合する、インサート成形を実施する際に、前記外側ホイール素子の軸方向他側の径方向内端部にディスクゲートの径方向外端部を位置させる事を特徴とする
ウォームホイールの製造方法。
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