CN1690477A - Worm gear mechanism and electric power steering apparatus equipped with the worm gear mechanism - Google Patents
Worm gear mechanism and electric power steering apparatus equipped with the worm gear mechanism Download PDFInfo
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- CN1690477A CN1690477A CN 200510051060 CN200510051060A CN1690477A CN 1690477 A CN1690477 A CN 1690477A CN 200510051060 CN200510051060 CN 200510051060 CN 200510051060 A CN200510051060 A CN 200510051060A CN 1690477 A CN1690477 A CN 1690477A
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Abstract
The purpose of this invention is to improve the state of the engagement of a worm with worm wheels by suppressing the hitting noise between the teeth of the worm and the worm wheels to increase the durability of a worm gear mechanism by a simple structure. This worm gear mechanism 44 comprises the worm 47, the worm wheel 48 for torque transmission engaged with the worm, and an auxiliary worm wheel 49 overlapped with the worm wheel for torque transmission. The pitch circle diameter of the auxiliary worm wheel is larger than the pitch circle diameter of the worm wheel for torque transmission. The auxiliary worm wheel is energized to the worm wheel for torque transmission by an energizing member 111 formed of a flat spring.
Description
Technical field
The present invention relates to the driven steering device of Worm gear mechanism and lift-launch Worm gear mechanism.
Background technique
Worm gear mechanism is by making the worm meshing of transmission of torque with worm gear and driving side, with worm gear torque being delivered to the driving mechanism of load side through transmission of torque from worm screw.In such Worm gear mechanism, developed the technology that suppresses backlash (for example, with reference to Japanese kokai publication hei 2001-355700 communique (the 3rd page, Fig. 1-3), Japanese kokai publication hei 2002-37100 communique (the 3rd page, Fig. 1-3)).
With the following described original Worm gear mechanism of Figure 17 brief description TOHKEMY 2001-355700 communique, with the following described original Worm gear mechanism of Figure 18 brief description TOHKEMY 2002-37100 communique.
Figure 17 (a)～(c) is the synoptic diagram (its 1) of original Worm gear mechanism, discloses the major component of Fig. 1～Fig. 3 of TOHKEMY 2001-355700 communique.(a) expression connects Worm gear mechanism 200 and electric motor 201.(b) cross-section structure of expression Worm gear mechanism 200.(c) meshing engagement structure of expression Worm gear mechanism 200.
Shown in Figure 17 (a), original Worm gear mechanism 200, the worm gear 204 of the passive side that engagement combines with output shaft 203 on the worm screw 202 of the driving side that is connected with electric motor 201.The 205th, worm shaft.
Worm gear 204, shown in Figure 17 (a)～(c), the elastomer 209 that flexibly is connected to by the wheel hub 206 that combines with output shaft 203, the 1st gear 207 of periphery that is configured in wheel hub 206 and the 2nd gear 208, with these the 1st, the 2nd gears 207,208 on the outer circumferential face of wheel hub 206 constitutes.
Promptly, with the worm gear 204 of worm screw 202 engagement at the length direction of output shaft 203, be to be divided into 2 gears (the 1st, the 2nd gear 207,208) on the running shaft direction, the phase place of these gears is staggered mutually, to sense of rotation these two gears are applied elastic force by elastomer 209.
Such Worm gear mechanism 200, the two sides by the gear 208a by the tooth 207a of the 1st gear 207 and the 2nd gear 208 seizes the tooth 202a of worm screw 202 in a circumferential direction on both sides by the arms from both sides suppresses backlash.
Figure 18 (a) and (b) are sketches (its 2) of original Worm gear mechanism, disclose Fig. 1 of TOHKEMY 2002-37100 communique and the major component of Fig. 3.(a) expression connects Worm gear mechanism 300 and electric motor 301.(b) cross-section structure of expression Worm gear mechanism.
Original Worm gear mechanism 300, shown in Figure 18 (a), on the worm screw 302 of the driving side that is connected with electric motor 301, the worm gear 304 of the passive side that engagement combines with output shaft 303.The 305th, motor drive shaft.
Shown in Figure 18 (b), the part (adding hatched part) of tooth 302a engagement among the tooth 311 of worm gear 304 and worm screw 302 is called meshing zone 312.
To the meshing zone 312 of the tooth 311 of worm gear 304, form the maintenance groove 313 of ring-type, the O type ring 321 of installation rubber system in this keeps groove 313 in side's side of its tooth 311 facewidth directions.
The O type circle 321 of rubber system, by contacting with the Topland 302b of worm screw 302, deflection a little is by adding that to mate precompressed suppresses backlash by its elastic recovering force.
, above-mentioned original Worm gear mechanism 200 shown in Figure 17 is owing to be divided into 2 parts, so the area of contact of the tooth 202a of 1 tooth of gear and worm screw 202 is below half on the running shaft direction.When making worm screw 202 positive rotation, from the tooth 207a that tooth 202a passes to the 1st gear 207, when counterrotating worm screw 202, make torque torque pass to the tooth 208a of the 2nd gear 208 from tooth 202a.Particularly, become the partitioning portion of the 1st gear 207 and the 2nd gear 208 at worm gear 204 and the contact pressure the best part (middle body of the figure left and right directions of Figure 17 (b)) of worm screw 202.Thereby,, have the leeway that can further study in order to improve the durability of Worm gear mechanism 200, particularly wearability.
In addition, above-mentioned original Worm gear mechanism 300 shown in Figure 180, on the position in the tooth 311 of worm gear 304, that leaving meshing zone 312, only the side in facewidth direction (left and right directions of figure) is formed with maintenance groove 313.To the flexural rigidity of transverse tooth thickness direction, different with opposite side in a side of facewidth direction.Its result, on a side and opposite side of facewidth direction, it is inhomogeneous that contact pressure becomes.Thereby,, the leeway that can further study is arranged in order to improve the durability of Worm gear mechanism 300.
Have again, above-mentioned original Worm gear mechanism 300 shown in Figure 180, because increment face 302 frictions of the worm screw 302 of the O type ring 321 of rubber system and rotation, so produce frictional force, and, bigger from the rotating center of worm gear 304 to the turning radius of the surface of contact of the O type ring 321 of rubber system.Its result produces big friction torque.In order to improve the transmission of torque efficient of Worm gear mechanism 300, preferably reduce big like this friction torque.
And, rubbing with Topland 302b because the O type ring 321 of rubber system is frequent, the durability in order to ensure the O type ring 321 of rubber system has further room for improvement.
In addition, in the occasion of these Worm gear mechanisms 200,300 being carried on driven steering device for example, when the steering dish, require to suppress further the generation of the sound that the tooth of gear clashes into mutually.Also require to reduce the indoor noise of car.
Have again, because driven steering device appends to the assist torque of electric motor on the steering system through Worm gear mechanism 200,300, so, preferably remove backlash in order to improve control feel (handle and feel).When backlash, when positive and negative direction of operating dish, can produce assist torque passes to steering system from Worm gear mechanism 200,300 time lag (synchronous hysteresis).
Summary of the invention
The objective of the invention is to, provide and further to improve the durability of Worm gear mechanism simultaneously with the generation of the mutual impact noise of the tooth between the simple STRUCTURE DEPRESSION worm and worm wheel, keep the technology of the good engagement of worm and worm wheel.
The invention of technological scheme 1 is a kind of Worm gear mechanism, by making the worm meshing of transmission of torque with worm gear and driving side, make torque pass to load side with worm gear from worm screw through transmission of torque, this Worm gear mechanism comprises the auxiliary worm wheel that overlaps with worm gear with the aforementioned torque transmission, it is characterized in that, the pitch diameter of this auxiliary worm wheel is set for bigger and make aforementioned auxiliary worm wheel and aforementioned worm meshing with the pitch diameter of worm gear, aforementioned auxiliary worm wheel is applied on the active force with the worm gear side to aforementioned transmission of torque with afterburning member than aforementioned torque transmission.
The invention of technological scheme 2 is characterized in that, aforementioned afterburning member is made of the discoid planar spring (comprising belleville spring) that is contained on the aforementioned auxiliary worm wheel, and the aforementioned torque transmission is supported this planar spring with worm gear.
The invention of technological scheme 3 is characterized in that, aforementioned planar spring and aforementioned torque transmission be with at least one side of worm gear, and the contacting part that will be used for the convex that contacts with mutual involutory the other side's face is formed on the position of regulation.
The invention of technological scheme 4 is characterized in that, aforementioned auxiliary worm wheel is a plastic article, forms the aforementioned planar spring that is made of another member.
The invention of technological scheme 5 is characterized in that, is provided with the aforementioned auxiliary worm wheel of restriction with respect to the rotation limting mechanism of aforementioned torque transmission with the relative swing offset of worm gear.
The invention of technological scheme 6 is the driven steering devices that carried Worm gear mechanism, it is characterized in that, comprise technological scheme 1, technological scheme 2, technological scheme 3, technological scheme 4 or technological scheme 5 Worm gear mechanism, steering system from the steering wheel of vehicle to steered wheel, produce the electric motor that aforementioned steering system is given this transmission of torque through aforementioned Worm gear mechanism in torque simultaneously.
In the invention of technological scheme 1, because it is big with the pitch diameter of worm gear that the pitch diameter of auxiliary worm wheel is set for the specific torque transmission, so can be with making auxiliary worm wheel and worm meshing with the different mesh phase of worm gear with transmission of torque, for this reason, can set for transmission of torque enough big with the facewidth of worm gear.Its result can guarantee the area of contact of transmission of torque with the tooth of the tooth of worm gear and worm screw fully.Thereby,, also can further improve durability even removed the Worm gear mechanism of backlash.
And, by making the structure of removing backlash, can further suppress the generation of worm screw and transmission of torque with the mutual impact noise of tooth between the worm gear.
Have again, in the invention of technological scheme 1,, can partly form bilateral symmetry shape to transmission of torque as the center and transmission of torque with the facewidth of worm gear with the part of worm gear and worm meshing when when axially seeing worm screw., unlike original, be provided with and be used to keep backlash to suppress maintenance groove with on the tooth of worm gear in transmission of torque, can make it form one with part.Thereby, can improve the machining accuracy of transmission of torque with the tooth of worm gear, simultaneously, can keep the good engagement of transmission of torque with worm gear and worm screw.
Have again, in the invention of technological scheme 1, because auxiliary worm wheel is overlapped with worm gear with transmission of torque, with the worm gear side auxiliary worm wheel is applied active force to transmission of torque with afterburning member simultaneously, so can form the structure of the backlash between the tooth of the tooth (worm tooth) of having removed worm screw and auxiliary worm wheel.Thus, when worm screw is rotated, the auxiliary worm wheel specific torque transmission advanced line displacement of worm gear.
That is, can make the auxiliary worm wheel displacement with worm screw earlier, the displacement hysteresis than this auxiliary worm wheel begins rotating torques transmission worm gear with worm screw.Its result can make the tooth of worm screw contact the tooth of transmission of torque with worm gear lenitively.For this reason, can further improve the durability of Worm gear mechanism.And, can further suppress worm screw and transmission of torque with producing the noise that tooth clashes into mutually between the worm gear.
For example, the core of auxiliary worm wheel is installed in transmission of torque with the occasion on the worm gear in mode with the restriction rotation, when the rotating force of worm screw passes on the auxiliary worm wheel, the following such component of effect.That is, according to the pressure angle of the tooth of worm screw, the effect tooth top is to the component of the direction of the footpath of worm screw foreign side displacement on auxiliary worm wheel.This component makes auxiliary worm wheel revolt the active force of afterburning member, to leaving the direction displacement of transmission of torque with worm gear.Opposite with above-mentioned component, the pushing force of pushing member becomes resistance.Thereby, can revolt resistance, make auxiliary worm wheel to leaving the direction displacement of transmission of torque with worm screw earlier with worm gear, the displacement hysteresis than this auxiliary worm wheel begins with worm screw rotating torques transmission worm gear.Its result can make the tooth of worm screw contact the tooth of transmission of torque with worm gear lenitively.For this reason, can further improve the durability of Worm gear mechanism.And, can suppress worm screw and transmission of torque further with producing the noise that tooth clashes into mutually between the worm gear.
So, by auxiliary worm wheel is overlapped with worm gear with transmission of torque, with the worm gear side auxiliary worm wheel is applied the simple structure of active force simultaneously to transmission of torque with afterburning member, can remove the backlash between the tooth of the tooth of worm screw and auxiliary worm wheel, improve the durability of Worm gear mechanism, suppress worm screw and transmission of torque simultaneously with producing the noise that tooth clashes into mutually between the worm gear.
In the invention of technological scheme 2, owing to constitute afterburning member by the discoid planar spring (comprising the dish spring) that is installed on the auxiliary worm wheel, transmission of torque is with worm gear bearing flat plate spring, so can reduce the number of spare parts of Worm gear mechanism.And owing to be planar spring, so can easily it be installed on the auxiliary worm wheel.
In the invention of technological scheme 3, on at least one side in planar spring and transmission of torque usefulness worm gear, the contacting part of the convex that is used for contacting with relative mutually the other side's face is formed on assigned position, so can stably remain on transmission of torque to auxiliary worm wheel with on the worm gear.This is owing to can apply precompression to planar spring by the contacting part of convex.Thus, can more suitably suppress the generation of mutual impact noise of tooth between worm screw and the auxiliary worm wheel and worm screw and transmission of torque with the mutual impact noise of the tooth between the worm gear.
In the invention of technological scheme 4, by planar spring being formed on the auxiliary worm wheel that constitutes by resin forming product, can prevent assembly error, can prevent the off-centre of planar spring and auxiliary worm wheel especially.Its result can prevent the worm screw that caused by off-centre and the bad engagement of auxiliary worm wheel.
Have again, owing to do not need to be used for planar spring is installed in fastening pieces such as bolt on the auxiliary worm wheel or rivet, so can make its lightweight.Because auxiliary worm wheel is a plastic article, so it is in light weight.Therefore, reduced to have installed the quality of the auxiliary worm wheel integral body of planar spring,, can reduce the inertial force of auxiliary worm wheel by having reduced quality.Because inertial force is little, so when auxiliary worm wheel begins to rotate, therefore the impact force that affacts on the planar spring from auxiliary worm wheel is also little, just can deal with problems and the stress of planar spring is little, can be by realizing lightweight with the diminish thickness that correspondingly reduces planar spring etc. of its stress.Like this, by reduction the quality of the auxiliary worm wheel integral body of planar spring has been installed, for example, in steering device for motor vehicle, use the occasion of this Worm gear mechanism, especially the responsiveness that handwheel rotates can be improved, therefore, the control feel (handling sense) of the steering gear can be improved more.
In the invention of technological scheme 5, be provided with the restriction auxiliary worm wheel with respect to the rotation limting mechanism of transmission of torque with the relative swing offset of worm gear.
For example, the core of auxiliary worm wheel is installed in transmission of torque with the occasion on the worm gear in mode with restriction rotation, auxiliary worm wheel is easy with the location transfiguration of worm gear with respect to transmission of torque, can be easily and carry out both assemblings reliably.In the structure on this Worm gear mechanism being installed in steering device for motor vehicle for example, even the occasion on the impact force action Worm gear mechanism that brings by road surface reaction etc., or have the occasion that timeliness changes, also can keep auxiliary worm wheel in position reliably with the relative position relation of worm gear with respect to transmission of torque and go up.
In addition, auxiliary worm wheel is mounted to slide with worm gear with respect to transmission of torque in counterrotating occasion, by limiting counterrotating scope, can keep auxiliary worm wheel and transmission of torque synchronous more reliably with the rotation of worm gear.
In the invention of technological scheme 6, owing in driven steering device, adopted Worm gear mechanism for the power transmitting deice of steering system, so can further improve the durability of the Worm gear mechanism of having removed backlash the transmission of torque that produces by electric motor.
Have, by removing the backlash of Worm gear mechanism, produce the mutual impact noise of between cog in the time of can further suppressing the steering dish, its result can further reduce the indoor noise of car.
Have again, in the invention of technological scheme 6,, can keep the good engagement of transmission of torque with worm gear and worm screw by removing the backlash of Worm gear mechanism.For this reason, when the direction of operating dish, can suppress assist torque is delivered to steering system from Worm gear mechanism time lag.
Have again,,,, contact lentamente and mesh, so can realize the rotational action of good steering wheel because tooth collides each other in the occasion that makes transmission of torque with the worm gear rotation with worm screw owing to removed backlash.
Therefore, can further improve the control feel (handling sense) of driven steering device.
Description of drawings
Fig. 1 is the schematic representation of driven steering device of the present invention (the 1st mode of execution).
Fig. 2 is the overall structure figure of driven steering device of the present invention (the 1st mode of execution).
Fig. 3 is the 3-3 line sectional drawing of Fig. 2.
Fig. 4 is the sectional drawing of the 4-4 line of Fig. 2.。
Fig. 5 is the sectional drawing of Worm gear mechanism of the present invention (the 1st mode of execution).
Fig. 6 is the exploded view of Worm gear mechanism of the present invention (the 1st mode of execution).
Fig. 7 is the plan view of Worm gear mechanism of the present invention (the 1st mode of execution).
Fig. 8 is worm screw in expression Worm gear mechanism of the present invention (the 1st mode of execution) and the transmission of torque structural drawing with the engagement of worm gear and auxiliary worm wheel.
Fig. 9 is the schematic representation of Worm gear mechanism of the present invention (the 1st mode of execution).
Figure 10 is the action diagram of Worm gear mechanism of the present invention (the 1st mode of execution).
Figure 11 is the sectional drawing of Worm gear mechanism of the present invention (the 1st variation).
Figure 12 is the sectional drawing of Worm gear mechanism of the present invention (the 2nd variation).
Figure 13 is the sectional drawing of Worm gear mechanism of the present invention (the 2nd mode of execution).
Figure 14 is the exploded view of Worm gear mechanism of the present invention (the 2nd mode of execution).
Figure 15 is the structural drawing of the engagement of worm screw in expression Worm gear mechanism of the present invention (the 2nd mode of execution) and the auxiliary worm wheel action diagram of holding concurrently.
Figure 16 is worm screw in expression Worm gear mechanism of the present invention (the 2nd mode of execution) and transmission of torque with the structural drawing of the engagement of worm gear and the auxiliary worm wheel action diagram of holding concurrently.
Figure 17 is the sketch (its 1) of original Worm gear mechanism.
Figure 18 is the sketch (its 2) of original Worm gear mechanism.
Embodiment
Describe being used to implement preferred forms of the present invention with reference to the accompanying drawings below.The following describes the example of Worm gear mechanism lift-launch on driven steering device.
At first, according to Fig. 1～Figure 10, the 1st mode of execution of driven steering device and Worm gear mechanism is described.
Fig. 1 is the schematic representation of driven steering device of the present invention (the 1st mode of execution).Driven steering device 10 is by assist torque mechanism 40 formations that add assist torque from the steering wheel 21 of vehicle to the steering system 20 of the steered wheel (front-wheel) 29 of vehicle, in this steering system 20.
In steering system 20, by universal shaft coupling 23,23 pinion shaft (input shaft) and steering wheel 21 are linked, by rack and pinion mechanism 25 rack shaft 26 and pinion shaft 24 are linked, through about drag link 27,27 and joint 28,28 two ends of left and right sides steered wheel 29,29 and rack shaft 26 are linked.
Rack and pinion mechanism 25 constitutes by being formed on small gear 31 on the pinion shaft 24 and the tooth bar 32 that is formed on the rack shaft 26.
Adopt steering system 20, by pilot control steering wheel 21, this turn to torque can via rack and pinion mechanism 25 and about the steered wheel 29,29 of drag link 27,27 about making turn to.
In assist torque mechanism 40, with turning to torque sensor 41 to detect 20 torques that turn to that are added on the steering wheel 21 of steering system system, turn to the torque testing signal of torque sensor 41 to produce control signal based on this at control device 42, produce the assist torque corresponding based on this control signal by electric motor 43 with turning to torque, via Worm gear mechanism 44 assist torque is delivered on the pinion shaft 24, again assist torque is delivered on the rack and pinion mechanism 25 of steering system 20 from pinion shaft 24.
Adopt driven steering device 10, the compound torque of the assist torque by adding electric motor 43 in the torque turning to of driver can turn to above-mentioned steered wheel 29,29 with rack shaft 26.
Fig. 2 is all pie graphs of driven steering device of the present invention (the 1st mode of execution), is to dissect the figure that left part and right part are represented.The figure shows rack shaft 26, be housed in the housing 51 that vehicle-width direction (figure left and right directions) is extended in mode in axial sliding driven steering device 10.
Fig. 3 is the 3-3 line sectional drawing of Fig. 2, the longitudinal section structure of expression driven steering device 10.
Driven steering device 10 pinion shaft 24, rack and pinion mechanism 25, turn to torque sensor 41, and Worm gear mechanism 44 be accommodated in the housing 51, stop up the upper opening of these housings 51 with upper cover 54.Turn to torque sensor 41 to be installed on the upper cover 54.
Turning to torque sensor 41 is by being arranged on the 1st residual deformation portion 61 and the 2nd residual deformation portion 62 on the pinion shaft 24, being arranged on the magnetostriction type sensor that the detection units 63 around these the 1st, the 2nd residual deformation portions 61,62 constitute.
1st, 2 residual deformation portions 61,62 are made of the magnetostrictive film that gives rightabout residual deformation on the shaft length direction of pinion shaft 24, and according to the effect torque that acts on these magnetostrictive films, Magnetostrictive Properties changes.
Detection unit 63 detects the magnetostrictive effect that produces in electric mode in the 1st, the 2nd residual deformation portion 61,62, its testing signal is exported as the torque testing signal.This detection unit 63 by the coil of wire skeleton 64,65 of the tubular that has passed pinion shaft 24, be wound on the 1st several-layer solenoid coiling coil 66 and the 2nd several-layer solenoid coiling coil 67 on the coil of wire skeleton 63,65, be trapped among the 1st, the 2nd several-layer solenoid coiling coil 66,67 around magnetic shielding constitute with supporting yoke 68.
Tooth bar guide rail 70 is the pushing and pressing mechanism that are made of the rail portion 71 that contacts with rack shaft 26 from the side opposite with tooth bar 32, adjustment bolt 73 by pressure spring 72 pushing rail portion 71.Between rail portion 71 and adjustment bolt 73, on the adjustment direction of adjusting bolt 73, some gaps are arranged.Rail portion 71 has the contact element 74 that slides on the back side of rack shaft 26.The 75th, will adjust the locking nut of bolt 73 with respect to housing 51 location.
By tooth bar guide rail 70 supporting rack shafts 26, this rack shaft 26 can endwisely slip to it.Use tooth bar guide rail 70, by pushing rail portion 71 via pressure spring 72 with suitable pushing force with the adjustment bolt 73 that screws on the housing 51, can be with rail portion 71 to giving pressure with tooth bar 32 and tooth bar 32 being pressed against on the small gear 31.
Fig. 4 is 4～4 line sectional drawings of Fig. 2, the relation of expression pinion shaft 24 and electric motor 43 and Worm gear mechanism 44.
As shown in Figures 3 and 4, Worm gear mechanism 44 is that an assist torque with electric motor 43 generations is delivered to the assist torque transfer mechanism on the pinion shaft 24, promptly is boosting mechanism.
If detailed word, Worm gear mechanism 44 by the worm shaft 46 that is connected with the motor drive shaft 43a of electric motor 43 by connector 45, with the integrally formed worm screw 47 of worm shaft 46, and the transmission of torque that meshes of worm screw 47 constitute with worm gear 48.Transmission of torque combines with pinion shaft 24 with worm gear 48.
The two end part that housing 51 rotatably supports horizontally extending worm shaft 46 by bearing 81,82.
Fig. 5 is the sectional drawing of Worm gear mechanism of the present invention (the 1st mode of execution), makes it corresponding with Fig. 3, only represents left-half.Fig. 6 is the exploded view of Worm gear mechanism of the present invention (the 1st mode of execution).Fig. 7 is the plan view of Worm gear mechanism of the present invention (the 1st mode of execution), dissects the part of auxiliary worm wheel 49 and represents.
As Fig. 5 and shown in Figure 6, transmission of torque with worm gear 48 be enclosed within hub portion cylindraceous (wheel hub) 101 on the pinion shaft 24, discoid worm gear body 102 integrally formed on the periphery of hub portion 101, a plurality of tooth 103... that on the outer circumferential face of worm gear body 102, form (... represent a plurality of.Below identical) constitute, be the gear of integrally formed product.
Contacting part 107 is at the outstanding male member in the position of regulation on the one side 102a relative with auxiliary worm wheel 49.That is, contacting part 107 is to be the protuberance of the ring-type of benchmark with transmission of torque with the rotating center CL of worm gear 48, and the central diameter of its annulus is Dc.Rotating center CL also is the center of pinion shaft 24.
A plurality of through hole 108... be with transmission of torque with the rotating center CL of worm gear 48 be benchmark and equidistantly arrange in a circumferential direction be seen as the roughly hole of fan-shaped from the top.These through holes 108... is in the center C L side (in the footpath side) of contacting part 107.
As Fig. 5 and shown in Figure 6, auxiliary worm wheel 49 is in order to eliminate the equipment gear that worm screw 47 and transmission of torque are provided with the backlash between the worm gear 48, to be and worm screw 47 meshed gears.Such auxiliary worm wheel 49 overlaps with the one side 102a of worm gear body 102, can not rotate with worm gear 48 with respect to transmission of torque.The center of auxiliary worm wheel 49 is identical with the rotating center CL of worm gear 48 with transmission of torque.
Explain auxiliary worm wheel 49 below.
As Fig. 5～shown in Figure 7, a plurality of through hole 115... and a plurality of contacting part 116... are arranged on the identical or roughly the same position (position of the circumference of diameter Dc shown in Figure 5) with respect to the contacting part 107 of transmission of torque with worm gear 48.These a plurality of through hole 115... and a plurality of contacting part 116... equidistantly arrange.
As shown in Figure 6, through hole 115... is communicated with the through hole 108... of transmission of torque with worm gear 48, sees it is the hole of fan-shaped roughly from the top.
As Fig. 5～shown in Figure 7, a plurality of contacting part 116... are configured between each through hole 115,115, in planar spring 111, from transmission of torque with the relative outstanding projection of face 111a of worm gear 48.These projections are the convex of round pin shape, and the smooth end face of outstanding front end is contacted with the end face of contacting part 107.
Like this, transmission of torque is integrally formed on the position of regulation the contacting part 107 of convex with worm gear 48, and this contacting part 107 contacts with the face 111a with it is faced mutually in the planar spring 111.Planar spring 111 is integrally formed on the position of regulation a plurality of convex contacting part 116..., and these convex contacting parts 116... contacts with the face 102a relative with it among the worm gear 48 with transmission of torque.
In other words, planar spring 111 and transmission of torque are with at least one side of worm gear 48, the contacting part 107 of the convex that is used for contacting with relative mutually the other side's face, the position that 116... is formed on regulation.
As Fig. 5 and shown in Figure 6, auxiliary worm wheel 49 is installed in transmission of torque with on the worm gear 48 by the axle collar 141, spline member 151 and nut 161.
As shown in Figure 6, the smooth stepped part 144 between the large-diameter portion 142 that the axle collar 141 is overlapped by the one side 102a with worm gear body 102, minor diameter part 143, large-diameter portion 142 and the minor diameter part 143 littler than the diameter of large-diameter portion 142 constitutes, and is the member of ring-type.
Spline member 151 is the smooth annular components that are made of sheet material, comprises a plurality of hook pawl 152... that extend with worm gear 48 to transmission of torque from the edge of periphery integratedly.As Figure 6 and Figure 7, the width of hook pawl 152... (size of circumferencial direction) is littler than each width (size of circumferencial direction) of through hole 108... and through hole 115....
As Fig. 5 and shown in Figure 6, the height of the minor diameter part 143 of the axle collar 141 adds that with the thickness of slab of planar spring 111 the whole height of thickness of slab of spline member 151 is identical or smaller than it.
As Fig. 5 and shown in Figure 6, according to such Worm gear mechanism 44, by the axle collar 141 being engaged on the extending portion 105 of hub portion 101, the matching hole 114 of planar spring 111 is engaged on the minor diameter part 143 of the axle collar 141, face cooperates spline member 151 from it, and face is spun on nut 161 on the outside thread 106 from it again, can be installed in transmission of torque to auxiliary worm wheel 49 with on the worm gear 48, that is, discoid planar spring 111 can be installed in transmission of torque to its core with on the worm gear 48.
Its result, the contacting part 116... of planar spring 111 directly contacts with the contacting part 107 of transmission of torque with worm gear 48.So, planar spring 111 directly contacts with worm gear 48 with transmission of torque.
With the rise to the bait structure of the hook pawl 152... that costs spline member 151 of the through hole 115... of the through hole 108... of worm gear 48 and auxiliary worm wheel 49, become the rotation limting mechanism 150 that is used to prevent by the rotation of the fastening auxiliary worm wheel that causes 49 of nut 161 in transmission of torque.Auxiliary worm wheel 49 is limited the hook of through hole 108..., 115... by hook pawl 152... with respect to the relative swing offset of transmission of torque with worm gear 48.
The composite construction of outside thread 106 and nut 161 and planar spring 111 constitutes and can be fixed on transmission of torque to auxiliary worm wheel 49 with the fixed mechanism 160 on the worm gear 48.That is, fixed mechanism 160 by auxiliary worm wheel 49 being pressed with worm gear 48 thrusters to transmission of torque through the planar spring 111 as afterburning member (resilient member) by nut 161, is fixed on transmission of torque to auxiliary worm wheel 49 with on the worm gear 48.
From above explanation as can be known, planar spring 111 is the afterburning members of auxiliary worm wheel 49 being pressed (suppressing) to transmission of torque with worm gear 48 thrusters.
As shown in Figure 7, the pitch diameter D2 specific torque transmission of auxiliary worm wheel 49 is with the big (D1＜D2) of the pitch diameter D1 of worm gear 48.
The profile of tooth of the tooth 131 of worm screw 47 is roughly trapezoidal profile of tooth become on the vertical section with axle, and transmission of torque is involute profile with the profile of tooth of the tooth 103 of worm gear 48 become on the vertical section with axle, and the worm tooth of worm screw 47 is 1, and the pitch of this worm tooth is Pi.
Fig. 8 (a)～(e) is the structural drawing of worm screw and the engagement of transmission of torque usefulness worm gear and auxiliary worm wheel in expression Worm gear mechanism of the present invention (the 1st mode of execution).The cross-sectional configuration of Fig. 8 (a) expression Worm gear mechanism 44 is figures corresponding with above-mentioned Fig. 5.The b-b line cross-section structure of Fig. 8 (b) presentation graphs 8 (a).
Shown in Fig. 8 (a) and Fig. 8 (b), be crown auxiliary worm wheel 49, mesh with worm screw 47 with the outer circumferential face 104 of worm gear 48 with making tooth 113... surround transmission of torque on the worm gear 48 by overlapping transmission of torque.For this reason, the tooth 113... of auxiliary worm wheel 49 does not interfere with worm gear 48 with transmission of torque.
Because it is big the pitch diameter D2 of auxiliary worm wheel 49 to be set for the pitch diameter D1 of specific torque transmission usefulness worm gear 48, so can be with the different mesh phase of worm gear 48 auxiliary worm wheel 49 being engaged on the worm screw 47 with transmission of torque.For this reason, can set transmission of torque for enough big (for example, roughly the same) with the facewidth of worm gear 48 with the external diameter of worm screw 47.Its result can fully guarantee the area of contact of transmission of torque with tooth 103 with the tooth 131 of worm screw 47 of worm gear 48.Thereby, can improve the durability of Worm gear mechanism 44 more.
Distance from the center of worm screw 47 to the pitch circle of auxiliary worm wheel 49 is r.This can be tried to achieve with following (1) formula apart from r.But the pitch diameter of the worm screw 47 when transmission of torque is meshed with worm screw 47 with worm gear 48 is decided to be d1.
r＝(D1+d1-D2)/2......(1)
Having, is arbitrarily apart from r again, but (that is, forward and backward) occasion is preferably 0 making worm screw 47 reversible rotations.More particularly, the size of pitch diameter D2 preferably auxiliaryly makes the tooth 113... of worm gear 49 and transmission of torque not interfere with worm gear 48, and auxiliary worm wheel 49 size that can mesh with worm screw 47.
Have, Worm gear mechanism 44 is characterised in that again, auxiliary worm wheel 49 formed so-called crown, makes the tooth 113... of auxiliary worm wheel 49 surround the outer circumferential face 104 of transmission of torque with worm gear 48.Thereby though added auxiliary worm wheel 49 in transmission of torque on worm gear 48, auxiliary worm wheel 49 is not interfered with worm gear 48 with transmission of torque.For this reason, can further set for transmission of torque enough big with the facewidth of worm gear 48.Thereby, can guarantee the area of contact of transmission of torque more fully with tooth 103 with the tooth 131 of worm screw 47 of worm gear 48.Thereby, can further improve the durability of Worm gear mechanism 44.
Also have, Worm gear mechanism 44 is characterised in that, the little (d1＞d2) of the pitch diameter d1 that the pitch diameter d2 of the worm screw 47 auxiliary worm wheel 49 during with worm screw 47 engagements sets specific torque transmission worm screw 47 during with worm screw 47 engagements with worm gear 48 for.
Because the spiral shell square Pi of the worm tooth (tooth) 131 of worm screw 47 fixes, and is relative therewith, the pitch diameter d2 of the worm screw 47 when auxiliary worm wheel 49 is meshed with worm screw 47 sets lessly, so can strengthen the lift angle of worm tooth 131 thus.If it is big that lift angle becomes, can reduce the frictional loss between worm screw 47 and the auxiliary worm wheel 49.That is, can improve transmission of torque efficient.Improve the corresponding torque that can reduce to be used to rotate the worm screw 47 of auxiliary worm wheel 49 with transmission of torque efficient.Thereby, Worm gear mechanism 44 is more successfully moved.Simultaneously, can improve the durability of Worm gear mechanism 44 more.
The c-c line cross-section structure of Fig. 8 (c) presentation graphs 8 (a), the expression transmission of torque engagement of worm gear 48 and worm screw 47.That is, transmission of torque contacts with the left flank of tooth 131a of the tooth 131 of worm gear pole 47 with the right flank of tooth 103b of the tooth 103 of worm gear 48.
The d-d line cross-section structure of Fig. 8 (d) presentation graphs 8 (a), the cross-section structure of Fig. 8 (b) is seen in Fig. 8 (e) expression from the e direction of arrow.The engagement of these Fig. 8 (d) and Fig. 8 (e) expression auxiliary worm wheel 49 and worm screw 47.That is, the left flank of tooth 113a of the tooth 113 of auxiliary worm wheel 49 contacts with the right flank of tooth 131b of the tooth 131 of worm screw 47.Between the right flank of tooth 113b of the tooth 113 of the left flank of tooth 131a of the tooth 131 of worm screw 47 and auxiliary worm wheel 49, backlash (gap) is arranged.
Fig. 9 is the schematic representation of Worm gear mechanism of the present invention (the 1st mode of execution), is the schematic representation that combination above-mentioned Fig. 8 (c) and Fig. 8 (d) represent.
Fig. 9 represents that (1) contacts the right flank of tooth 103b of transmission of torque with the tooth 103 of worm gear 48 on the left flank of tooth 131a of the tooth 131 of worm screw 47, and (2) have atomic little backlash (gap) between the left flank of tooth 113a of the tooth 113 of contact auxiliary worm wheel 49 on the right flank of tooth 131b of the tooth 131 of worm screw 47 or two flank of tooth simultaneously.Gear clearance B 1 under such engagement, B2 are as described below.
The size of the gear clearance B 1 between the tooth 131 of worm screw 47 and the tooth 113 of auxiliary worm wheel 49 is X1 (X1 for example is 0 or is roughly 0).Tooth 131 of worm screw 47 and transmission of torque are X2 with the size of the gear clearance B 2 between the tooth 103 of worm gear 48.Worm gear mechanism 44 is characterised in that it is little with the gear clearance B 2 of worm gear 48 sides that the gear clearance B 1 of auxiliary worm wheel 49 sides is set for the specific torque transmission.That is, the relation of X1 and X2 is (0≤X1＜X2).
According to Figure 10 the effect of above-mentioned Worm gear mechanism 44 is described below.Figure 10 (a)～(c) is the action diagram of Worm gear mechanism mechanism of the present invention (the 1st mode of execution).
Figure 10 (a) is the figure corresponding with above-mentioned Fig. 9, and the expression transmission of torque contacts with the left flank of tooth 131a of the tooth 131 of worm screw 47 with the right flank of tooth 103b of the tooth 103 of worm gear 48.Under this state, the gear clearance B 1 less (comprising B1=0) between the tooth 131 of worm screw 47 and the tooth 113 of auxiliary worm wheel 49.And gear clearance B 2 is arranged in right flank of tooth 131b one side of the tooth 131 of worm screw 47.
Under the state of this Figure 10 (a), when making worm screw 47 positive rotation with electric motor 43 (with reference to Fig. 3), the tooth 131 of worm screw 47 is to arrow R1 direction (figure right) displacement.Its result, the left flank of tooth 113a of the tooth 113 of the right flank of tooth 131b pushing auxiliary worm wheel 49 of the tooth 131 of worm screw 47.Corresponding to this pushing force, on left flank of tooth 113a, produce horizontal component and vertical stress component.
Promptly, according to the pressure angle of the tooth 131 of worm screw 47, on left flank of tooth 113a, produce the rotating force (horizontal component) that makes auxiliary worm wheel 49 rotations, make auxiliary worm wheel 49 to the direction of leaving worm screw 47, be the tooth top of auxiliary worm wheel 49 carries out displacement force (vertical stress component) from displacement to the direction of the footpath of worm screw 47 foreign side displacement.
The tooth 113 of auxiliary worm wheel 49 under the vertical stress component effect to the footpath of worm screw 47 foreign side (paper the place ahead of Figure 10 (a) to) displacement, in the tooth top side engagement of the tooth 131 of worm screw 47.
As described above, the pushing force (spring force) of the tooth 131 resistance planar springs 111 of worm screw 47, the tooth 113 that makes auxiliary worm wheel 49 simultaneously to the displacement of arrow R1 direction, arrives the state of Figure 10 (c) to the radially foreign side displacement of worm screw 47 through the state of Figure 10 (b).
Its result, shown in Figure 10 (c), the right flank of tooth 131b of the tooth 131 of worm screw 47 and transmission of torque contact and push this left side flank of tooth 103a with the left flank of tooth 103a of the tooth 103 of worm gear 48.Transmission of torque uses worm gear 48 to the displacement of arrow R2 direction.
Like this, also make auxiliary worm wheel 49 to axial displacement with worm screw 47 by the resistance of revolting auxiliary worm wheel 49, the displacement that can lag behind auxiliary worm wheel 49 makes transmission of torque begin rotation with worm gear 48 with worm screw 47.Auxiliary worm wheel 49 rotates with worm gear 48 with transmission of torque.
Its result can make the tooth 131 of worm screw 47 contact with the tooth 103 of transmission of torque with worm gear 48 lentamente.For this reason, can further improve the durability of Worm gear mechanism 44.And, owing to can eliminate gear clearance B 2, therefore can further suppress worm screw 47 and transmission of torque with producing the sound that tooth clashes into mutually between the worm gear 48.
As described above, the tooth of worm screw 47 131 is by the tooth 113 to arrow R1 direction pushing auxiliary worm wheel 49, and the elastic force pressure of resistance planar spring 111 (with reference to Fig. 5) axially upwards pushes away tooth 113 along pinion shaft 24 (with reference to Fig. 5).Then, under the state of Figure 10 (c), when making worm screw 47 counter-rotating with electric motor 43 (with reference to Fig. 3), its tooth 131 is to the direction opposite with arrow R1 (figure left to) displacement.Along with the right flank of tooth 131b of tooth 131 to the direction displacement opposite with arrow R1, the tooth 113 of auxiliary worm wheel 49 is pushed away and automatically returns to the state shown in Figure 10 (a) downwards by the elastic force pressure of planar spring 111.
So, can suppress worm screw 47 and transmission of torque are clashed into sound mutually with the tooth between the worm gear 48 103,131 generation.
And, shown in Fig. 8 (a), when when axially seeing worm screw 47, transmission of torque with the part of worm gear 48 and worm screw 47 engagements as center (promptly with respect to center line CW) by the worm screw 47 shown in Fig. 8 (a), can partly make the bilateral symmetry shape to transmission of torque with the facewidth of worm gear 48.And use on the tooth 103 of worm gear 48 in transmission of torque, be provided for keeping backlash to suppress to use the maintenance groove of part unlike original (with reference to Figure 18), and can form as one.Thereby can improve the machining accuracy of transmission of torque with the tooth 103 of worm gear 48, simultaneously can the holding torque transmission with the good engagement of worm gear 48 with worm screw 47.
Conclude above explanation, Worm gear mechanism 44 according to the 1st mode of execution, as Fig. 5 and shown in Figure 9, it is littler with the gear clearance B 2 between the tooth 103 of worm gear 48 by the gear clearance B 1 between the tooth 113 of tooth 131 of worm screw 47 and auxiliary worm wheel 49 is set for than tooth 131 and the transmission of torque of worm screw 47, auxiliary worm wheel 49 is overlapped with worm gear 48 with transmission of torque, the so simple structure of auxiliary worm wheel 49 being pressed with worm gear 48 thrusters to transmission of torque with afterburning member 111 simultaneously can improve the durability of Worm gear mechanism 44.
And gear clearance B 2 can suppress worm screw 47 and transmission of torque is clashed into sound mutually with producing tooth 103,131 between the worm gear 48 by eliminating.
Have again, as shown in Figure 5, by by fixed mechanism 160 through planar spring 111 to transmission of torque with worm gear 48 side pressure auxiliary worm wheels 49, can apply precompression to auxiliary worm wheel 49.
Thereby, as the 1st mode of execution, can use tooth 131 and transmission of torque that auxiliary worm wheel 49 successfully stably is pressed in worm screw 47 on the worm gear 48 by afterburning member 111.
Have again, adopt Worm gear mechanism 44, because the discoid planar spring 111 (comprising belleville spring) that is assembled in the auxiliary worm wheel 49 constitutes afterburning member 111, and planar spring 111 is directly contacted with worm gear 48 with transmission of torque, so the part number of Worm gear mechanism 44 is few.And owing to be planar spring 111, so can easily be assembled on the auxiliary worm wheel 49.
Have again, adopt Worm gear mechanism 44, owing to use at least one side of worm gear 48 at planar spring 111 and transmission of torque, contacting part 107, the 116... of the convex that is used for contacting with relative mutually the other side's face are integrated the position of stipulating, so can stably remain on transmission of torque to auxiliary worm wheel 49 with on the worm gear 48, thereby, can suppress the generation of worm screw 47 and transmission of torque more rightly with the mutual bump sound of the tooth 103,131 (with reference to Fig. 9) between the worm gear 48.
Have again, adopt Worm gear mechanism 44, form one owing to planar spring 111 is formed on the auxiliary worm wheel 49 that is made of the resin-shaped finished product and with auxiliary worm wheel 49, so can be integrated easily.
Have again, owing to do not need to be used for planar spring 111 is assembled into clamp structures such as bolt on the auxiliary worm wheel 49 or rivet, so can alleviate the weight of this part.Because auxiliary worm wheel 49 is plastic articles, so it is in light weight.For this reason, in the assembling auxiliary worm wheel 49 total qualities of planar spring 111 reduce.Owing to reduced quality, so can reduce the inertial force of auxiliary worm wheel 49.Because inertial force is little, when auxiliary worm wheel 49 began to rotate, the impact force that affacts on the planar spring 111 from auxiliary worm wheel 49 was also little.Thereby the stress of planar spring 111 is little, so can seek lightweight by waiting with its thickness of slab that correspondingly reduces planar spring 111.Like this, be assembled into the quality of auxiliary worm wheel 49 integral body of planar spring 111,, can have improved the control feel (handling sense) of the steering gear 10 more in the occasion that Worm gear mechanism 44 is used on the steering device for motor vehicle 10 by reduction.
Have, Worm gear mechanism 44 is provided with restriction auxiliary worm wheel 49 with respect to the rotation limting mechanism 150 of transmission of torque with worm gear 48 relative swing offsets again.
For example, the core of auxiliary worm wheel 49 is installed in transmission of torque with the occasion on the worm gear 48, carries out auxiliary worm wheel 49 easily with respect to the location of transmission of torque with worm gear 48 in the mode of rotating with restriction by rotation limting mechanism 150.Can assemble easily and reliably.This Worm gear mechanism 44 is being assembled in the structure of driven steering device 10, even the occasion of impact force action on Worm gear mechanism 44 of bringing in anti-power of work in road surface etc., perhaps have the occasion that long-term timeliness changes, also can maintain auxiliary worm wheel 49 reliably on the correct position with respect to the relative position relation of transmission of torque with worm gear 48.
Have again, for example, under the state of Figure 10 (a), carry out positive rotation and tooth 131 to the displacement of arrow R1 direction by worm screw 47, can at first make auxiliary worm wheel 49 displacements shown in Figure 10 (b) like that, shown in Figure 10 (c), make transmission of torque begin rotation then like that with worm gear 48.Its result can gently make the tooth 131 of worm screw 47 contact with the tooth 103 of transmission of torque with worm gear 48.
Next, the variation of the Worm gear mechanism 44 of above-mentioned the 1st mode of execution shown in Figure 5 is described according to Fig. 1 and Figure 12.For the structure mark identical drawing reference numeral identical, omit its explanation with the Worm gear mechanism 44 of the 1st mode of execution shown in Figure 5.
Figure 11 is the sectional drawing of Worm gear mechanism of the present invention (the 1st variation), illustrates accordingly with above-mentioned Fig. 5.
The Worm gear mechanism 44 of the 1st variation shown in Figure 11 is characterized in that, is made of the afterburning member (being resilient member) that auxiliary worm wheel 49 is suppressed with worm gear 48 sides to transmission of torque compression helical spring 171.
Figure 12 is the sectional drawing of Worm gear mechanism of the present invention (the 2nd variation), and is corresponding with above-mentioned Figure 11.
The Worm gear mechanism 44 of the 2nd distortion side shown in Figure 12, it is the variation of the further distortion of above-mentioned the 1st variation shown in Figure 11, it is characterized in that the whole auxiliary worm wheel 49 that is made of plastic article is from holding the effect of auxiliary worm wheel 49 to " the afterburning member " of using worm gear 48 thrusters to press in transmission of torque.
The auxiliary worm wheel 49 of the 2nd variation overlaps in transmission of torque to be used on the worm gear 48, and the while cooperates with pinion shaft 24 and is installed on the pinion shaft 24 with being limited to move axially.At length say, auxiliary worm wheel 49 by the 49a of hub portion that cooperates with pinion shaft 24, be formed on fastening hook portion 49b on the 49a of hub portion, be formed on the afterburning member 49c of the disk of thin wall shape on the outer peripheral portion of the 49a of hub portion, the worm gear main body portion 49d of the ring-type that on the outer peripheral portion of afterburning member 49c, forms and constitute.
By fastening hook portion 49b being hooked on transmission of torque, can be installed in transmission of torque to auxiliary worm wheel 49 with on the worm gear 48 with on the fastening recess 48a of worm gear 48.Afterburning member 49c pinion shaft 24 axially on can resiliently deformable, by elastic recovering force worm gear main body portion 49d is suppressed with worm gear 48 sides to transmission of torque.Worm gear main body portion 49d has a plurality of tooth 113....
By the elastic recovering force of pushing member 49c, can apply towards the precompressed of transmission of torque auxiliary worm wheel 49 with worm gear 48 sides.
According to the 2nd variation, can make the few simple structure of part number to Worm gear mechanism 44, the location of auxiliary worm wheel 49 is easy, can assemble easily and reliably.
Then, according to Figure 13～Figure 16, the 2nd mode of execution of driven steering device and Worm gear mechanism is described.The Worm gear mechanism 44A of the driven steering device 10 (with reference to Fig. 1) of the 2nd mode of execution is different with the 1st mode of execution, and other structure is identical.The identical reference character of structure mark for identical with the 1st mode of execution of above-mentioned Fig. 1～shown in Figure 10 omits its explanation.Above-mentioned Fig. 1～structure shown in Figure 4, owing to also be identical in the 2nd mode of execution, its diagram of Therefore, omited.
Figure 13 is the sectional drawing of Worm gear mechanism of the present invention (the 2nd mode of execution), and is corresponding with above-mentioned Fig. 5, only represented its left-half.Figure 14 is the exploded view of Worm gear mechanism of the present invention (the 2nd mode of execution).
As Figure 13 and shown in Figure 14, the Worm gear mechanism 44A of the 2nd mode of execution has changed the structure of transmission of torque with worm gear 48 and auxiliary worm wheel 49.Change to the Worm gear mechanism 44A of the 2nd mode of execution partly describes below.
Transmission of torque is characterised in that with worm gear 48, forms the smooth 102b of seat surface portion in the center of the one side 102a of worm gear body 102, is being formed with outside thread 106 from the 102b of seat surface portion to the fore-end of axially extended extending portion 105 simultaneously.Extending portion 105 has parallel 2 tabular surfaces 109,109 (tangent plane part) on outer circumferential face.
On the other hand, the planar spring 111 of auxiliary worm wheel 49 is characterised in that, tilts to middle body from worm gear body 112, and shape is the afterburning member (being resilient member) of so-called [dish spring] shape in the form of a truncated cone.The conical end is the installation face 117 that the tabular surface by level constitutes.This installation facial 117 has matching hole 114.The planar spring 111 of dish spring-like is configured to reduce to the direction of the one side 102a of worm gear body 102.Such auxiliary worm wheel 49 is installed facial 117 and is overlapped with the 102b of seat surface portion by making, and becomes the structure that overlaps with the one side 102a of worm gear body 102.
Owing to be such structure, by the matching hole 114 of planar spring 111 is cooperated with extending portion 105, again plain washer 181 is enclosed within on the extending portion 105, then nut 161 is spun on the external screw thread 106 of extending portion 105, can clamp securely by 102b of seat surface portion and nut 161 and install facial 117.Its result can use the core of auxiliary worm wheel 49 on the worm gear 48 by being installed in transmission of torque, and limits this auxiliary worm wheel 49 with respect to transmission of torque worm gear 48 rotations by clamping frictional force.
The Worm gear mechanism 44A of the 2nd mode of execution does not comprise contacting part 107, the 116... (with reference to Fig. 5) of the 1st mode of execution.And the planar spring 111 of the 2nd mode of execution is the afterburning member that auxiliary worm wheel 49 is suppressed (applying elastic force) to transmission of torque with worm gear 48 sides.Its result, auxiliary worm wheel 49 is meshed in the mode that is provided with backlash with worm screw 47.
The matching hole 182 of plain washer 181 has parallel 2 tabular surfaces 183,183 that match with the section configuration of extending portion 105.For this reason, be limited with respect to the relative rotation of transmission of torque with the plain washer 181 that extending portion 105 cooperates with worm gear 48.
The composite structure of parallel 2 tabular surfaces 183,183 that be formed on parallel 2 tabular surfaces 109,109 on the outer circumferential face of extending portion 105, be located in plain washer 181 between planar spring 111 and the nut 161, form on the matching hole 182 of plain washer 181 forms rotation limting mechanism 180.
That does like this reasons are as follows, when assembling Worm gear mechanism 44A, in the position of the tooth 113... that makes auxiliary worm wheel 49 with after worm screw 47 and transmission of torque are aimed at worm gear 48, screw-in nut 161.At this moment, plain washer 181 does not rotate with worm gear 48 with respect to transmission of torque with nut 161.Thereby, when assembling, can prevent the position deflection of the tooth 113 of auxiliary worm wheel 49.
As the 2nd mode of execution, in the occasion of with worm gear 48 restrictions the core of auxiliary worm wheel 49 being installed rotatably with respect to transmission of torque, auxiliary worm wheel 49R is become easily with respect to the location of transmission of torque with worm gear 48, can be easily and carry out its assembling reliably.In this Worm gear mechanism 44A being assembled into the structure of driven steering device 10 (with reference to Fig. 1) for example, even the occasion of impact force action on turbine mechanism 44A of being brought in road surface counter-force etc., perhaps have the occasion that timeliness changes, also can maintain auxiliary worm wheel 49 and the relative position relation of transmission of torque reliably on the correct position with worm gear 48.Its result can keep the synchronous rotation with worm gear 48 of auxiliary worm wheel 49, worm screw 47 and transmission of torque stably in a long term.
Figure 15 (a)～(d) is the structural drawing of the worm screw of expression Worm gear mechanism of the present invention (the 2nd mode of execution) and the engagement of the auxiliary worm wheel action diagram of holding concurrently.But omitted transmission of torque worm gear 48.
(a) being the figure of the cross-section structure of expression Worm gear mechanism 44A, is the figure corresponding with above-mentioned Figure 13.(b) be direction shown in the arrow b of (a) to view, the cross-section structure that expression is seen from the rotating center side of auxiliary worm wheel 49.(c) be the figure that amplifies the major component of expression (b).(d) be the figure that represents the effect of Worm gear mechanism 44A with (c) accordingly.
As shown in figure 13, the core of planar spring 111 is installed in transmission of torque with on the worm gear 48.For this reason, auxiliary worm wheel 49 can revolt the pushing force of planar spring 111 and arrow R3 shown in Figure 15 (a) is such, to the direction of leaving worm screw 47, promptly to the radially foreign side displacement of worm screw.
Shown in Figure 15 (a)～(c), when worm screw 47 was in halted state, on the position P1 of the pitch diameter d2 of worm screw 47, auxiliary worm wheel 49 was not meshed with worm screw 47 with having backlash.
When worm screw 47 positive rotation, its tooth 131 is to arrow R1 direction (circle right) displacement.Its result, shown in Figure 15 (c), the left flank of tooth 113a of the tooth 113 of the right flank of tooth 131b pushing auxiliary worm wheel 49 of the tooth 131 of worm screw 47.When this pushing force is made as f1, exposure level component f2 and vertical stress component f3 on left flank of tooth 113a.
Promptly, when the pressure angle of the tooth 131 of establishing worm screw 47 is α, α is corresponding with pressure angle, on left flank of tooth 113a, effect make rotating force (horizontal component) f2 of auxiliary worm wheel 49 rotation and make auxiliary worm wheel 49 to the direction of leaving worm screw 47, be displacement force (vertical stress component) f3 of the tooth top of auxiliary worm wheel 49 to direction (the arrow R3 direction) displacement of the radially foreign side displacement of worm screw 47.
Under the effect of displacement force f3, auxiliary worm wheel 49 is to the result of arrow R3 direction displacement, and shown in Figure 15 (d), the tooth 113 of auxiliary worm wheel 49 is in the engagement of the some P2 place of the tooth top side of the tooth 131 of worm screw 47.
That is, the elastic force pressure of the tooth of worm screw 47 131 resistance planar springs 111 (with reference to Figure 13) is to an arrow R1 direction mobile displacement Y1, its result, and the engaging position changes to a P2 from a P1.The elastic force pressure of planar spring 111 is the rotational resistances to the directive effect that auxiliary worm wheel 49 is restored.
Figure 16 (a)～(d) is worm screw in expression Worm gear mechanism of the present invention (the 2nd mode of execution) and transmission of torque with the structural drawing of the engagement of worm gear and the auxiliary worm wheel action diagram of holding concurrently.(a) being the ideograph of the Worm gear mechanism 44A under the neutral condition, is the figure that equally schematically represents with above-mentioned Fig. 9, (b) be direction shown in the arrow b of (a) to view, the worm screw 47 that expression is seen from the rotating center side and the cross-section structure of auxiliary worm wheel 49.(c) be the tooth 131 and the schematic representation of transmission of torque of worm screw 47 with the Worm gear mechanism 44A under tooth 103 state of contact of worm gear 48.(d) d that is (c) is to view, the worm screw 47 that expression is seen from the rotating center side and the cross-section structure of auxiliary worm wheel 49.
Figure 16 (a) and Figure 16 (b) are illustrated under the neutral condition, the state that transmission of torque is meshed under the state of the gear clearance B 4 with same size, B4 with the left and right tooth 103,103 of worm gear 48 and the tooth 131 of worm screw 47.This engagement is kept by making auxiliary worm wheel 49 and worm screw 47 not have gear clearance B 3 ground to be meshed.
The big or small X3 of the gear clearance B 3 between the tooth 131 of worm screw 47 and the tooth 113 of auxiliary worm wheel 49 is 0 (zero).Tooth 131 of worm screw 47 and transmission of torque are X4 with the size of the gear clearance B 4 between the tooth 103 of worm gear 48.Like this, Worm gear mechanism 44A is characterised in that it is little with the gear clearance B 4 of worm gear 48 sides that the gear clearance B 3 of auxiliary worm wheel 49 sides is set for the specific torque transmission.That is, be the relation of " X3＜(X4 * 2) ".In fact, even the big or small X3 of the gear clearance B 3 of auxiliary worm wheel 49 sides than 0 bigger value also it doesn't matter.
Thereby under neutral condition, transmission of torque does not contact with the tooth 131 of worm screw 47 with the left and right tooth 103,103 of worm gear 48.For this reason, at beginning rotary worm 47 constantly, between tooth 131,103, do not produce friction torque.
Under this state, when worm screw 47 carried out positive rotation, its tooth 131 was to arrow R1 direction (figure right) displacement.Its result, shown in Figure 16 (b), the left flank of tooth 113a butt of the right flank of tooth 131b of the tooth 131 of worm screw 47 and the tooth 113 of auxiliary worm wheel 49 also pushes this tooth 113.Auxiliary worm wheel 49 to the direction of leaving from worm screw 47, be radially foreign side (the arrow R3 direction) displacement of worm screw 47.
Its result, shown in Figure 16 (d), the tooth 113 of auxiliary worm wheel 49 is meshed with it on the position of the tooth top side of the tooth 131 of worm screw 47.That is, the result that both engaging position of 131b, 113a change, the tooth 131 that makes worm screw 47 is to the displacement of arrow R1 direction.
So, under the state shown in Figure 16 (a) and (b), tooth 131 is to gear clearance B 4 amounts of an arrow R1 direction displacement transmission of torque with worm gear 48 sides, the result, shown in Figure 16 (c), the right flank of tooth 131b of the tooth 131 of worm screw 47 and transmission of torque contact and push tooth 113 with the left flank of tooth 113a of the tooth 113 of worm gear 48.The transmission of torque that is urged is rotated to arrow R2 direction with worm gear 48.
As from as indicated in the above explanation.Can make of the radially foreign side displacement of the tooth 113 of auxiliary worm wheel 49 by the rotational resistance that planar spring 111 produces by worm screw 47 resistances, lag behind some again by worm screw 47 beginning rotating torques transmission worm gears 48 to worm screw 47.Then, auxiliary worm wheel 49 rotates with worm gear 48 with transmission of torque.
So, the tooth 131 of worm screw 47 is gently contacted with the tooth 103 of transmission of torque with worm gear 48.Therefore, can further improve the durability of Worm gear mechanism 44.And, owing to can remove gear clearance B 4, so can suppress the generation of worm screw 47 and transmission of torque more with the mutual bump sound of the tooth between the worm gear 48 103,131.
Then, when under the state of Figure 16 (c), (d), when making worm screw 47 counter-rotatings by electric motor 43 (with reference to Fig. 3), its tooth 131 is to the direction opposite with arrow R1 (figure left and right directions) displacement.Along with the right flank of tooth 131b of tooth 131 to the direction displacement opposite with arrow R1, the tooth 113 of auxiliary worm wheel 49 is pushed away downwards by the elastic force pressure of planar spring 111 (with reference to Figure 13) and automatically turns back to the state shown in Figure 16 (a) and (b).
So, can suppress the generation of worm screw 47 and transmission of torque better with the mutual impact noise of the tooth between the worm gear 48 103,131.
In sum, as shown in figure 13, the Worm gear mechanism 44A of the 2nd mode of execution, rotatably the central part of auxiliary worm wheel 49 be installed in transmission of torque with worm gear 48 on respect to transmission of torque with worm gear 48 owing to limit it, so when the rotating force of worm screw 47 is delivered to auxiliary worm wheel 49, to the following such component of its effect.That is, as shown in figure 15, corresponding to the pressure angle α of the tooth 131 of worm screw 47, the effect tooth top is to the component of the direction of the radially foreign side displacement of worm screw 47 on the tooth 113 of auxiliary worm wheel 49.As Figure 13 and shown in Figure 16, this component makes the pushing force of auxiliary worm wheel 49 resistance pushing members 111 to leaving the direction displacement of transmission of torque with worm gear 48.With respect to above-mentioned component, the active force of afterburning member 111 becomes resistance.
Thereby, can make auxiliary worm wheel 49 to the departure direction displacement by worm screw 47 resistance resistances earlier, lag a little while, by worm screw 47 beginning rotating torques transmission worm gears 48.Its result can make the tooth 131 of worm screw 47 gently contact the tooth 103 of transmission of torque with worm gear 48.For this reason, can further improve the durability of Worm gear mechanism 44A.And, owing to can remove gear clearance B 4, so can suppress the generation of worm screw 47 and transmission of torque better with the mutual impact noise of the tooth between the worm gear 48 131,103.
So, can set the gear clearance B 3 between the tooth 113 of tooth 131 of worm screw 47 and auxiliary worm wheel 49 than tooth 131 of worm screw 47 and the gear clearance B 4 between the transmission of torque usefulness tooth 103 of worm gear 48 for, B4 is little, auxiliary worm wheel 49 is overlapped with worm gear 48 with transmission of torque, simultaneously by auxiliary worm wheel 49 being suppressed such simple structure to transmission of torque with worm gear 48 sides by afterburning member 111, can improve the durability of Worm gear mechanism 44A, and, can remove gear clearance B 4, B4 and suppress worm screw 47 and transmission of torque with the tooth 131 between the worm gear 48, the generation of 103 mutual impact noises.
The Worm gear mechanism 44 of other effect and effect and above-mentioned the 1st mode of execution identical.
Have, the electric motor of the driven steering device of technological scheme 6 is not limited to the structure that produces the assist torque corresponding with the testing signal of handling torque again, also can be the structure that produces torque and this torque is passed to steering system through Worm gear mechanism.
In addition, in embodiments of the present invention and variation, as to transmission of torque with worm gear 48 sides to auxiliary worm wheel 49 apply active force the resilient member of afterburning member, the structure of the afterburning member 49c (with reference to Figure 12) of the thin-walled plate-like that be not limited to planar spring 111 (with reference to Fig. 5, Figure 13), compression helical spring 171 (with reference to Figure 11), on auxiliary worm wheel 49, forms.Planar spring 111 comprises the structure of dish spring.
In addition, size for the active force of the afterburning member that constitutes by planar spring 111 (with reference to Fig. 5, Figure 13) or compression helical spring 171 (with reference to Figure 11), perhaps the size of the active force of the afterburning member 49c (with reference to Figure 12) of disk of thin wall shape needs only suitably and sets.For example, at a high speed or in driving at moderate speed, can set the size of the active force of afterburning member, so that the mutual bump sound of the tooth can suppress to handle driven steering device 10 (with reference to Fig. 1) time 103,131 at vehicle.In order to improve the indoor livability of car, preferably suppress at a high speed or the bump sound in driving at moderate speed.
In addition, auxiliary worm wheel 49 also can be with respect to transmission of torque worm gear 48 revolvable structures.
For example, with the rotation limting mechanism 150 of Fig. 5～shown in Figure 7 with auxiliary worm wheel 49 with worm gear 48 slidably and can counterrotating mode be installed to transmission of torque with the occasion on the worm gear 48 with respect to transmission of torque, by limiting counterrotating scope, it is synchronous with the rotation of worm gear 48 to keep auxiliary worm wheel 49 and transmission of torque more reliably.
In this occasion, under the state of Figure 10 (a), by worm screw 47 positive rotation and tooth 131 to the displacement of arrow R1 direction, shown in Figure 10 (b), can at first revolt rotational resistance and make auxiliary worm wheel 49 rotations, shown in Figure 10 (c), some make transmission of torque rotate with worm gear 48 with respect to these auxiliary worm wheel 49 rotation hysteresis for another example.Its result can make the tooth 131 of worm screw 47 gently contact with the tooth 103 of transmission of torque with worm gear 48.
Worm gear mechanism of the present invention is suitable for, with the torque that turns to that turns to the torque sensor detection with the steering wheel generation, turn to the testing signal of torque sensor according to this, electric motor produces assist torque, is the vehicle driven steering device that this assist torque passes to steering system suitable by above-mentioned Worm gear mechanism.
Claims (6)
1. a Worm gear mechanism by making the worm meshing of transmission of torque with worm gear and driving side, makes torque pass to load side via transmission of torque with worm gear from worm screw,
This Worm gear mechanism comprise with the aforementioned torque transmission with the auxiliary worm wheel that worm gear overlaps, it is characterized in that
The pitch diameter of this auxiliary worm wheel is set for bigger with the pitch diameter of worm gear, is made aforementioned auxiliary worm wheel and aforementioned worm meshing than aforementioned torque transmission,
With the worm gear side aforementioned auxiliary worm wheel is applied active force to aforementioned transmission of torque with afterburning member.
2. Worm gear mechanism as claimed in claim 1 is characterized in that, aforementioned afterburning member is made of the discoid planar spring that is contained on the aforementioned auxiliary worm wheel, and the aforementioned torque transmission is supported this planar spring with worm gear.
3. Worm gear mechanism as claimed in claim 2 is characterized in that, aforementioned planar spring and aforementioned torque transmission be with at least one side in the worm gear, and the contacting part that will be used for the convex that contacts with relative mutually the other side's face is formed on the position of regulation.
4. as claim 2 or 3 described Worm gear mechanisms, it is characterized in that aforementioned auxiliary worm wheel is a plastic article, and the aforementioned planar spring that is shaped and constitutes by another member with being integral with it.
5. as claim 1,2,3 or 4 described Worm gear mechanisms, it is characterized in that, be provided with the aforementioned auxiliary worm wheel of restriction with respect to the rotation limting mechanism of aforementioned torque transmission with the relative swing offset of worm gear.
6. driven steering device that carries Worm gear mechanism, it is characterized in that, comprise claim 1,2,3,4 or 5 Worm gear mechanism, steering system, produce the electric motor that aforementioned steering system is given this transmission of torque through aforementioned Worm gear mechanism in torque simultaneously from the steering wheel of vehicle to steered wheel.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP130251/2004 | 2004-04-26 | ||
| JP2004130251 | 2004-04-26 | ||
| JP005452/2005 | 2005-01-12 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1690477A true CN1690477A (en) | 2005-11-02 |
| CN100392292C CN100392292C (en) | 2008-06-04 |
Family
ID=35346126
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2005100510607A Expired - Fee Related CN100392292C (en) | 2004-04-26 | 2005-03-01 | Worm gear mechanism and electric power steering apparatus equipped with the worm gear mechanism |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN100392292C (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102815333A (en) * | 2011-06-10 | 2012-12-12 | 罗伯特·博世有限公司 | Steering system in vehicle |
| CN102893057A (en) * | 2010-08-23 | 2013-01-23 | 本田技研工业株式会社 | Worm gear mechanism and electric power steering device using same |
| CN104093622A (en) * | 2012-02-13 | 2014-10-08 | 南阳工业株式会社 | MDPS worm gear and method for manufacturing same |
| CN104470786A (en) * | 2012-02-20 | 2015-03-25 | 施密特集团股份公司 | Gear rack steering gear having a progressive reduction |
| CN113423960A (en) * | 2019-02-12 | 2021-09-21 | 日本精工株式会社 | Worm gear reducer and electric assist device |
| CN113874180A (en) * | 2019-03-25 | 2021-12-31 | 库卡德国有限公司 | Mechanical overload switching mechanism |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3567963B2 (en) * | 1997-10-13 | 2004-09-22 | トヨタ自動車株式会社 | Hypoid gear structure |
| GB9822603D0 (en) * | 1998-10-17 | 1998-12-09 | Trw Lucas Varity Electric | Improvements relating to electric power steering systems |
| JP2001355700A (en) * | 2000-06-15 | 2001-12-26 | Nok Vibracoustic Kk | Vibration control structure for electric power steering device |
| JP3641742B2 (en) * | 2000-07-24 | 2005-04-27 | 光洋精工株式会社 | Electric steering device |
| JP3639948B2 (en) * | 2000-07-24 | 2005-04-20 | 光洋精工株式会社 | Electric steering device |
-
2005
- 2005-03-01 CN CNB2005100510607A patent/CN100392292C/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102893057A (en) * | 2010-08-23 | 2013-01-23 | 本田技研工业株式会社 | Worm gear mechanism and electric power steering device using same |
| CN102815333A (en) * | 2011-06-10 | 2012-12-12 | 罗伯特·博世有限公司 | Steering system in vehicle |
| CN104093622A (en) * | 2012-02-13 | 2014-10-08 | 南阳工业株式会社 | MDPS worm gear and method for manufacturing same |
| CN104470786A (en) * | 2012-02-20 | 2015-03-25 | 施密特集团股份公司 | Gear rack steering gear having a progressive reduction |
| CN104470786B (en) * | 2012-02-20 | 2017-03-22 | 施密特集团股份公司 | Gear rack steering gear having a progressive reduction |
| CN113423960A (en) * | 2019-02-12 | 2021-09-21 | 日本精工株式会社 | Worm gear reducer and electric assist device |
| CN113874180A (en) * | 2019-03-25 | 2021-12-31 | 库卡德国有限公司 | Mechanical overload switching mechanism |
| CN113874180B (en) * | 2019-03-25 | 2024-03-19 | 库卡德国有限公司 | Mechanical overload switching mechanism |
Also Published As
| Publication number | Publication date |
|---|---|
| CN100392292C (en) | 2008-06-04 |
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