JP2003074676A - Reduction gear mechanism and electric power steering device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow the correction to a proper backlash quantity in the increase or decrease of the distance between the rotating centers of a small gear and a large gear by the change in temperature or humidity of a reduction mechanism part. SOLUTION: This reduction gear mechanism comprises: a worm wheel 2 at least a teeth part 21 of which is made of a synthetic resin; a worm 1 meshed with the worm wheel 2; and a housing 3a for totatably supporting the worm wheel 2 and the worm 1 through a transmission shaft 5 and a shaft part 1b. A synthetic resin-made bearing member 40 capable of changing the distance H between the rotating centers of the worm wheel 2 and the worm 1 according to the expansion of the teeth part 21 is interposed between the housing 3a and the shaft part 1b to allow the correction to the proper backlash quantity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reduction gear mechanism including two gears meshing with each other and a support body that rotatably supports the gears, and an electric power steering apparatus using the reduction gear mechanism.

[0002]

2. Description of the Related Art The steering of an automobile is arranged outside a vehicle compartment for steering a steering wheel (generally a front wheel) for rotating a steering wheel arranged inside the vehicle compartment. It is performed by telling the steering mechanism.

FIG. 19 is a sectional view of a conventional electric power steering apparatus, and FIG. 20 is a sectional view of a reduction gear mechanism portion. As an electric power steering device for an automobile, for example, as shown in FIGS. 19 and 20, a steering shaft 101 having a torsion bar 102 connected to a steering wheel 100 for steering and rotating the steering wheel 100 A torque sensor 103 that detects the torque applied to the steering shaft 101, a steering assist motor 104 that is driven based on the detection result of the torque sensor 103, and the motor 10
A reduction gear mechanism 10 that connects the rotation of No. 4 to the steering shaft 101.
5, a transmission means 106 for transmitting the steering mechanism to the steering mechanism,
The operation of the steering mechanism according to the rotation of the steered wheels 100 is assisted by the rotation of the motor 104, and the labor load of the driver for steering is reduced.

The reduction gear mechanism 105 includes the motor 104.
Worm 107 that is interlocked with the rotation of the
A worm wheel 108 that meshes with the steering shaft 101 and is fitted to the steering shaft 101, and a housing 109 that rotatably supports the worm 107 and the steering shaft 101.

The worm 107 is arranged so as to intersect with the axis of the steering shaft 101, and the two rolling bearings 11 are provided.
Fitting hole 1 in the housing 109 through 0, 111
It is supported by 12, 113 and is prevented from moving in the radial direction and the axial direction. ing.

The worm wheel 108 is the worm 1
07 has a synthetic resin annular tooth portion 114 meshing with 07 and a metallic fitting body 115 fitted inside the annular tooth portion 114. The fitting body 115 is fitted and supported on the steering shaft 101. However, the annular tooth portion 114 reduces noise caused by meshing with the worm 107. Also,
The steering shaft 101 is supported by fitting holes 119, 120, 121 in the housing 109 via a needle bearing 116 and two rolling bearings 117, 118, and movement of the worm wheel 108 in the radial direction and the axial direction is prevented. ing.

In the electric power steering device using the worm 107 and the worm wheel 108 as described above, the worm 107 and the worm wheel 1 are used.
The meshing portion of 08 is provided with an appropriate amount of backlash so that the worm 107 and the worm wheel 108 can rotate smoothly. When the amount of backlash is large, a rattling noise is generated, and the rattling sound is leaked into the interior of the vehicle. When the amount of backlash in the meshing portion is small, the worm 107 and the worm wheel 10 are used.
It becomes impossible to rotate 8 smoothly.

[0008]

However, in the conventional electric power steering apparatus configured as described above, the worm 107 and the worm wheel 108 are prevented from moving in the radial direction, and the worm 107 and the worm wheel 108 are prevented. Since the distance between the rotation centers of the reduction gear mechanism 10 is fixed, the ambient temperature is high, and the heat generated by the motor 104 is transmitted to the reduction gear mechanism 10.
When the temperature of the five parts becomes relatively high or when the humidity becomes relatively high, meshing clogging occurs, and improvement measures have been demanded.

As a result of the inventor's investigation into the cause of the clogging of the mesh, the clogging of the mesh is caused by the annular tooth portion 114 and the fitting body 11.
It has been found out that this often occurs in the electric power steering apparatus including the worm wheel 108 having the number 5. As a result of further pursuit, worm 107
And housing 10 for supporting the worm wheel 108
Reference numeral 9 is made of aluminum, and the annular tooth portion 114 of the worm wheel 108 having the annular tooth portion 114 and the fitting body 115 fitted inside the annular tooth portion 114 is made of synthetic resin.
The fitting 115 and the worm 107 are made of metal,
Despite the difference in the linear expansion coefficient of the materials, the individual parts are only processed to the allowable dimensions without considering the linear expansion coefficient. Even if the lash amount was appropriate, a large difference in the thermal expansion amount of the individual parts due to the temperature increase and humidity increase of the reduction gear mechanism 105 part, the backlash amount becomes too small, and the meshing clogging occurs. Further, it was found that the reduction amount of the reduction gear mechanism 105 causes a large difference in the contraction amount of each component due to the temperature decrease and the humidity decrease, the backlash amount becomes excessive, and the noise is generated.

When the linear expansion coefficient α of the metal fitting 115 and the worm 107, the linear expansion coefficient β of the synthetic resin annular tooth portion 114, and the linear expansion coefficient γ of the aluminum housing 109 are used, The expansion coefficient γ and the linear expansion coefficient α have a high γ at a ratio of about 2: 1, and the linear expansion coefficient β and the linear expansion coefficient α have a high β at a ratio of about 7.5: 1, and β>
Since γ> α, the backlash amount between the worm 107 and the worm wheel 108 becomes too small due to the temperature increase and the humidity increase in the reduction gear mechanism 105, and the temperature decrease and the humidity decrease in the reduction gear mechanism 105 part. The amount of backlash between the worm 107 and the worm wheel 108 becomes excessive.

The present invention has been made in view of such circumstances, and has a reduction gear mechanism and an electric power steering which can correct the amount of backlash between the small gear and the large gear regardless of temperature and humidity. To provide a device.

[0012]

A reduction gear mechanism according to a first invention comprises a small gear, a large gear meshing with the small gear, and a housing rotatably supporting the small gear and the large gear. In the reduction gear mechanism, the housing is divided into a first housing body that supports the small gear and a second housing body that supports the large gear, and the housing is divided between the first housing body and the second housing body. And a rotation center distance changing means capable of changing the rotation center distance between the small gear and the large gear.

An electric power steering apparatus according to a twelfth aspect of the present invention is a motor for steering assistance connected to the reduction gear mechanism according to any one of claims 1 to 11 and the small gear or the second gear. And a transmission means for transmitting the rotational force of the large gear or the first gear accompanying the rotation of the motor to the steering mechanism.

In the first invention and the twelfth invention, the temperature of the reduction gear mechanism part assembled at room temperature (about 20 ° C.),
When the backlash amount becomes excessively small due to the increase in humidity, the rotation center distance changing means provided between the first housing body and the second housing body changes the rotation center distance between the small gear and the large gear. Can be made longer, so it is possible to correct the backlash amount appropriately. Also, when the backlash amount becomes excessive due to the decrease in temperature and humidity of the reduction gear mechanism part,
Since the distance between the rotation centers can be shortened by the rotation center distance changing means, the backlash amount can be corrected to an appropriate value.

The reduction gear mechanism according to the second aspect of the invention is characterized in that the means for changing the distance between the rotation centers comprises a connecting member for connecting the first housing body and the second housing body.

According to the second aspect of the invention, when the backlash amount becomes excessively small due to the temperature and humidity of the speed reduction gear mechanism part assembled at room temperature (about 20 ° C.) rising, the first housing body is used. Since the distance between the rotation centers of the small gear and the large gear can be automatically lengthened by the connecting member connecting the second housing body, it is possible to correct the amount of backlash. In addition, when the backlash amount becomes excessive due to the temperature and humidity of the reduction gear mechanism portion decreasing, the distance between the rotation centers can be automatically shortened by the connecting member, so that a proper backlash can be achieved. It can be adjusted to the amount of rush.

In the reduction gear mechanism according to a third aspect of the present invention, the large gear has a tooth portion made of synthetic resin which meshes with the small gear, and the rotation center distance changing means is the first housing body and the first housing body. It is characterized by comprising a synthetic resin connecting member for connecting the two housing bodies.

According to the third invention, when the temperature and humidity of the speed reduction gear mechanism part assembled at room temperature (about 20 ° C.) rises and the teeth of the synthetic resin expand, the first housing body. Also, the connecting member that connects the second housing body automatically expands at a rate close to the expansion rate of the tooth portion, and the distance between the rotation centers automatically increases to correct the backlash amount. it can. Further, when the temperature and humidity of the reduction gear mechanism portion decrease and the synthetic resin tooth portion contracts, the connecting member automatically contracts at a rate close to the contraction rate of the tooth portion, and The distance will be automatically shortened, and you can correct the amount of backlash.

A reduction gear mechanism according to a fourth aspect of the present invention is characterized in that the connecting member is made of a synthetic resin material similar to the tooth portion.

According to the fourth aspect of the invention, since the connecting member is made of the same kind of synthetic resin material having a linear expansion coefficient similar to that of the teeth, it is assembled at room temperature (about 20 ° C.). As the temperature and humidity of the reduction gear mechanism portion rise, the tooth portion and the connecting member of the large gear expand at a substantially equal ratio, and the backlash amount can be automatically corrected to a more appropriate amount. Also, because the temperature and humidity of the reduction gear mechanism part will decrease, the teeth of the large gear and the connecting member will contract at approximately the same ratio, so it is necessary to automatically correct the backlash amount to a more appropriate amount. You can

A reduction gear mechanism according to a fifth aspect of the present invention includes a first gear having at least teeth made of synthetic resin, a second gear meshing with the gear, and a support member rotatably supporting each of the gears. In the reduction gear mechanism including the above, the support member has a rotation center distance changing means capable of changing the rotation center distance of the first and second gears.

According to the fifth aspect of the invention, when the tooth portion expands due to moisture absorption over time and the backlash amount becomes too small, the rotation center distance changing means provided in the support member is used. Since the distance between the rotation centers of the gears can be increased, the amount of backlash can be corrected to an appropriate value.

In the reduction gear mechanism according to a sixth aspect of the present invention, the support member has a shaft coupled to the gear and a housing into which the shaft is fitted, and the rotation center distance changing means is the It is characterized by comprising a bearing member interposed between the shaft and the housing and capable of being deformed in a radial direction in which the distance between the rotation centers becomes long.

In the reduction gear mechanism according to a seventh aspect of the present invention, the bearing member has a fixed portion fixed to the housing and a fitting hole fitted to the shaft, and is arranged in a direction opposite to the fixed portion. And a bearing part capable of being deformed.

In the sixth invention and the seventh invention, when the influence of moisture absorption of the first gear is small, it is possible to support the gear in an appropriate position without causing center runout, and moreover, with time of the tooth portion. When the amount of backlash is too small due to moisture absorption, the bearing portion of the bearing member is deformed, the distance between the rotation centers of the gears can be increased, and the amount of backlash can be corrected to an appropriate value.

A reduction gear mechanism according to an eighth aspect of the invention is characterized in that a space is provided between the bearing portion and the housing to allow deformation of the bearing portion.

In the eighth aspect, when the tooth portion expands due to moisture absorption over time, the bearing portion is deformed in the space, so that the bearing portion can be favorably deformed according to the moisture absorption over time of the gear. .

In the reduction gear mechanism according to the ninth aspect of the invention, the housing has a support hole for supporting the bearing member, and the bearing member has a recess to be bent in the support hole. It is characterized by

According to the ninth aspect of the invention, the bearing member can be fixed at an appropriate position by fitting the bearing member into the support hole, and the bearing member can be easily assembled.

The reduction gear mechanism according to the tenth aspect of the invention is characterized in that the bearing member is made of synthetic resin.

In the tenth aspect of the invention, when the tooth portion expands due to moisture absorption over time and the backlash amount becomes too small, the bearing member automatically expands at a rate close to the expansion rate of the tooth portion. As a result, the distance between the rotation centers is automatically lengthened, and the backlash amount can be corrected to an appropriate value.

In the reduction gear mechanism according to an eleventh aspect of the present invention, the shaft is provided on both sides of the gear, and the bearing member is provided with two bearing cylinders fitted to the shafts, respectively, and the bearing cylinder. And a coupling portion that couples with each other, and the bearing member is fitted inside the housing.

According to the eleventh aspect, the distance between the centers of rotation can be changed on both sides of the gear by the two bearing tubular portions, and moreover, the positions of the two bearing tubular portions with respect to the housing can be made equal.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings showing the embodiments thereof. Embodiment 1 FIG. 1 is a vertical cross-sectional view of Embodiment 1 of a reduction gear mechanism, and FIG. 2 is a cross-sectional view of Embodiment 1 of a reduction gear mechanism. The reduction gear mechanism A rotatably supports the worm 1 made of metal (mainly mild steel) having shafts 1a and 1b at both ends, a worm wheel 2 meshing with the worm 1, and the worm 1 and the worm wheel 2. And a housing 3 made of aluminum, and one shaft portion 1a of the worm 1
It is configured to reduce the rotation of the motor 4 connected to the worm wheel 2 and transmit it to the worm wheel 2.

The worm wheel 2 is a synthetic resin annular tooth portion 21 having a plurality of teeth that mesh with the worm 1.
And a metal (mainly mild steel) fitting body 22 fitted inside the tooth portion 21, and the transmission shaft 5 is fitted and fixed in a through hole 23 bored in the central portion of the fitting body 22. Has been done.
The tooth portion 21 is made of nylon resin, for example.

The housing 3 accommodates the worm 1, and the shaft portions 1a and 1b of the worm 1 are rolling bearings 6 and 7.
The first housing body 31 made of aluminum rotatably supported via the worm wheel 2 is housed, and the worm wheel 2 is fitted to the transmission shaft 5 and both sides in the axial direction of the transmission shaft 5. It is divided into a second housing body 32 made of aluminum supported through rolling bearings 8 and 9, and the divided ends of the first housing body 31 and the second housing body 32 are the worm 1 and the worm wheel 2. Are connected by a connecting member 10 capable of changing the distance H between the rotation centers.

The first housing body 31 is elongated in the axial direction of the worm 1, and the fitting holes 31a and 31b and the fitting hole 31 are provided on both sides of the arrangement area in which the worm 1 is arranged.
Screw holes 31c and 31d connected to a and 31b are provided, and the shaft portions 1a and 1b of the worm 1 are rotatably supported in the fitting holes 31a and 31b through the rolling bearings 6 and 7, respectively. There is. A screw ring 33 for fixing one rolling bearing 6 is screwed into one screw hole 31c, and a lid 34 is screwed into the other screw hole 31d. Further, the motor 4 having a cylindrical portion is attached outside the one screw hole 31c.

The second housing body 32 has a pair of rolling bearings 8 on both sides of an arrangement area in which the worm wheel 2 is arranged.
Support hole 3 for rotatably supporting the transmission shaft 5 via 9
2a and 32b are provided.

The connecting member 10 is made of a synthetic resin material equal to that of the tooth portion 21 or a similar synthetic resin material having a linear expansion coefficient similar to that of the tooth portion 21, for example, nylon resin. The thickness t in the radial direction of the tooth portion 21 interposed between the divided ends of the housing body 31 and the second housing body 32 (the dimension from the fitting surface fitted to the fitting body 22 to the pitch circle of the teeth). Width dimension t'which is almost equal to
And a flange 10b, 10b connected to both ends in the longitudinal direction of the connection 10a, and the surfaces of the flange 10b, 10b and the connection 10a are fused to the divided end face portion. Thus, the split ends of the first housing body 31 and the second housing body 32 are connected.

The reduction gear mechanism A thus constructed is
For example, it is used in an electric power steering device. FIG. 3 is a sectional view of the electric power steering apparatus according to the present invention. The electric power steering device has a steering shaft 12 having one end connected to a steering wheel 11 for steering and a tubular portion at the other end, and one end coaxial with the other end of the steering shaft 12 inserted into the tubular portion. Steering wheel 11
A torsion bar 13 which is twisted by the action of a steering torque applied thereto, the transmission shaft 5 whose other end is coaxially connected to the other end of the torsion bar 13, a steering shaft 12 corresponding to the torsion of the torsion bar 13, A torque sensor 14 that detects a steering torque applied to the steered wheels 11 based on a relative rotational displacement amount of the transmission shaft 5, the steering assisting motor 4 that is driven based on the torque detected by the torque sensor 14, and the motor. 4 is provided with the reduction gear mechanism A for decelerating the rotation and transmitting the rotation to the transmission shaft 5, and a housing 15 in which the torque sensor 14 is housed. The housing 15 is the second housing body 32. It is molded integrally with.

The reduction gear mechanism A includes a shaft portion 1a of the worm 1.
Is connected to the output shaft 4a of the motor 4, and the worm wheel 2 is fitted and fixed in the middle of the transmission shaft 5. The meshing of the worm 1 and the worm wheel 2 prevents the rotation of the output shaft 4a. It is decelerated and transmitted to the transmission shaft 5, and transmitted from the transmission shaft 5 to a rack and pinion type steering mechanism (not shown) through a universal joint. The transmission shaft 5 and the universal joint form a transmission unit that transmits the rotational force of the worm wheel 2 to the steering mechanism.

In the reduction gear mechanism A and the electric power steering device configured as described above, the linear expansion coefficient α of the worm 1 and the fitting body 22, the linear expansion coefficient β of the tooth portion 21, the first housing body 31 and the second housing. When the linear expansion coefficient γ of the body 32 is set, the linear expansion coefficient γ and the linear expansion coefficient α are high in a ratio of about 2: 1, and the linear expansion coefficient β and the linear expansion coefficient α are about 7.5. Β is high at a ratio of: 1 and β>γ> α
The respective members are made of materials having a large difference in linear expansion coefficient. In the present invention, the worm 1
The first housing body 31 supporting the worm wheel 2 and the second housing body 32 supporting the worm wheel 2 are connected by a similar synthetic resin material having a linear expansion coefficient similar to that of the tooth portion 21 made of synthetic resin. Because the temperature rises,
When the tooth portion 21 expands due to an increase in humidity, the connecting member 10 expands at a ratio substantially equal to that of the tooth portion 21, and the tooth portion 2 is expanded due to a temperature decrease and a humidity decrease.
When 1 contracts, the connecting member 10 contracts at a ratio almost equal to that of the tooth portion 21, and the expansion and contraction of the tooth portion 21 can be absorbed by the connecting member 10, so that an appropriate backlash amount is obtained. Can be modified.
The proper backlash amount is about 20 to 40μ.
m.

Therefore, the ambient temperature of the reduction gear mechanism A is high, or the heat generated by the motor 4 is generated by the reduction gear mechanism A.
If the temperature of the reduction gear mechanism A becomes relatively higher than the room temperature at the time of assembly or the humidity becomes relatively higher than the humidity at the time of assembly, the teeth of the worm wheel 2 Since the portion 21 and the connecting member 10 expand at a substantially equal ratio, the distance H between the rotation centers of the worm 1 and the worm wheel 2 can be increased, and the backlash amount can be corrected to an appropriate amount.

When the ambient temperature of the reduction gear mechanism A becomes relatively lower than the room temperature at the time of assembling, or the humidity becomes relatively lower than the humidity at the time of assembling, the tooth portion of the worm wheel 2 is 21 and connecting member 10
And will contract at approximately the same rate, and worm 1
Also, the distance H between the rotation centers of the worm wheel 2 can be shortened, and the backlash amount can be corrected to an appropriate value.

In the embodiment described above, the first housing body 31 supporting the worm 1 and the second housing body 32 supporting the worm wheel 2 have the linear expansion coefficient of the tooth portion 21 made of synthetic resin. The members are connected by the connecting member 10 made of the same type of synthetic resin material having an approximate linear expansion coefficient, but the connecting member 10 can also reduce the ratio of the linear expansion coefficient β to the linear expansion coefficient α. Alternatively, a non-synthetic resin material may be used.

Embodiment 2 FIG. 4 is an enlarged cross-sectional view of the essential parts of Embodiment 2 of the reduction gear mechanism. In the reduction gear mechanism of the second embodiment, instead of fusing the connecting member 10 for connecting the divided ends of the first housing body 31 and the second housing body 32 to the divided ends, a plurality of connecting members 10 are provided. The first housing body 31 and the second housing body 3 are attached by attaching with the tightening screws 16.
The two divided ends are connected.

A plurality of first mounting holes 31e parallel to the center of rotation of the worm 1 are formed in the divided end portion of the first housing body 31, and the worm 1 is formed in the divided end portion of the second housing body 32. Second mounting holes 32 parallel to the center of rotation of the
c is drilled.

Further, the collar portions 10b, 10b of the connecting member 10
Has through holes 10c and 10d corresponding to the first mounting hole 31e and the second mounting hole 32c, respectively, and is inserted from the through holes 10c and 10d into the first mounting hole 31e and the second mounting hole 32c. The tightening screw 16 ...
By attaching b and 10b to the divided ends, the first
The housing body 31 and the second housing body 32 are connected.

Since other configurations and operations are similar to those of the first embodiment, the same parts are designated by the same reference numerals,
The detailed explanation and the explanation of the action and effect are omitted.

Third Embodiment In the reduction gear mechanism A of the third embodiment, instead of dividing the housing 3 into a first housing body 31 and a second housing body 32, the worm 1 in the housing 3 in the axial direction of the worm 1 is divided. A slit (not shown) that is long in the axial direction is provided in the above-mentioned divided portion on the other side to divide the housing into halves, and the worm side of this half portion can be slightly bent in the contact and separation direction. A resin member (not shown) made of a similar synthetic resin material or the like having a linear expansion coefficient similar to the linear expansion coefficient of the tooth portion 21 is attached to.

In the third embodiment, since the worm side of the half-divided portion of the housing 3 can be bent,
When the tooth portion 21 expands or contracts, the resin member expands or contracts at a ratio substantially equal to the tooth portion 21, the worm side of the half part of the housing 3 slightly bends, and the distance H between the rotation centers is changed. It is possible to correct the amount of backlash.

Since other configurations and operations are the same as those of the first embodiment, the same parts are designated by the same reference numerals,
The detailed explanation and the explanation of the action and effect are omitted.

Fourth Embodiment FIG. 5 is an enlarged sectional view of a main part of a reduction gear mechanism according to a fourth embodiment, and FIG. 6 is an enlarged sectional view taken along line VI-VI of FIG. In the reduction gear mechanism A according to the fourth embodiment, instead of dividing the housing 3, the shaft member 1b, which is a supporting member, includes a bearing member 40 that can be deformed in a direction in which the distance H between the rotation centers increases. And the housing 3a.

In the fourth embodiment, the housing 3a, which is a support member that rotatably supports the worm 1 and the worm wheel 2, is made of aluminum integrally formed to accommodate the worm 1 and the worm wheel 2. The first and second support holes 35 and 36 for supporting the shaft portions 1a and 1b via the rolling bearings 6 and 7 are separated from each other in the accommodating chamber that accommodates the worm 1 in the axial direction of the worm 1. Is provided. One rolling bearing 6 arranged on the side of the motor 4 is fitted and supported in the circular first support hole 35, and the other rolling bearing 7 arranged on the side opposite to the motor is arranged via the bearing member 40. It is supported by two support holes 36.

The second support hole 36 is formed in a non-circular shape that is long in the direction in which the distance H between the rotation centers increases.
A fixing portion 36a for fixing a part of the bearing member 40 is provided on one side in the longitudinal direction.

The bearing member 40 is made of a similar synthetic resin material having a linear expansion coefficient similar to that of the tooth portion 21, for example, nylon resin, and a fixed portion 40a fixed to the fixed portion 36a, The rolling bearing 7 has a fitting hole 40b into which the rolling bearing 7 is fitted, and a bearing portion 40c capable of being deformed in the opposite direction from the fixed portion 40a by expansion. The fixed portion 40a is fixed to the fixed portion 36a. The distance H between the rotation centers is set to be appropriate in the state of being fixed to. Further, between the bearing portion 40c and the second support hole 36, there is a space 17 which is allowed to be deformed in the direction in which the distance H between the rotation centers of the bearing portion 40c becomes longer. Bearing part 4
The deformation amount of 0c is within a range in which the rotation center line of the worm 1 is inclined due to the gaps between the inner ring and the outer ring of the rolling bearings 6 and 7 fitted to the shaft portion 1a and the rolling elements, for example, 0 to It is 150 μm. The bearing member 40 and the second support hole 36 constitute a rotation center distance changing means.

In the fourth embodiment, since the shaft portion 1b of the worm 1 is supported by the bearing member 40 made of synthetic resin similar to the tooth portion 21 made of synthetic resin, the temperature of the reduction gear mechanism A portion is reduced. When the tooth portion 21 expands because the temperature becomes relatively higher than the room temperature at the time of assembling, or the humidity becomes relatively higher than the humidity at the time of assembling, at a ratio substantially equal to that of the tooth portion 21. The bearing portion 40c of the bearing member 40 expands in the space 17, and the shaft portion 1b fitted in the fitting hole 40b via the rolling bearing 7 can be biased so that the distance H between the rotation centers becomes long. it can. As a result, the distance H between the rotation centers of the worm 1 and the worm wheel 2 can be increased, and the backlash amount can be corrected to an appropriate value.

The bearing member 40 has a fixed portion 40a.
Is fixed to the fixed portion 36a of the housing 3a, and further, the bearing portion 40c is deformable in the radial direction in which the distance H between the rotation centers becomes long.
When the effect of moisture absorption is small, it is possible to support the worm 1 at an appropriate position without swinging the core.

Since other configurations and operations are similar to those of the first embodiment, the same parts are designated by the same reference numerals,
The detailed explanation and the explanation of the action and effect are omitted.

Fifth Embodiment FIG. 7 is an enlarged cross-sectional view of the essential parts of the fifth embodiment of the reduction gear mechanism, and FIG. 8 is a diagram showing the relationship between the amount of backlash and the torque applied to the mesh portion of the worm and the worm wheel. is there. The reduction gear mechanism A of the fifth embodiment has an annular shape having a recess 41 to be bent in the radial direction in the circular second support hole 36 instead of the bearing member 40 of the fourth embodiment. The bearing member 42 is used, and the bearing member 42 is
The support hole 36 is fitted and supported.

In the fifth embodiment, the bearing member 42 has a fitting hole 42a into which the rolling bearing 7 is fitted by a similar synthetic resin material having a linear expansion coefficient similar to that of the tooth portion 21. A plurality of V-shaped recesses 41 to be bent in the radial direction in which the distance H between the rotation centers is long are formed in a part of the outer peripheral surface so as to be spaced apart in the circumferential direction, and are adjacent to each other. The convex portion 42b between the recesses 41 can be bent.

Further, between the second support hole 36 and the bearing member 42, a positioning mechanism 18 for determining the position of the recess 41 in the bearing member 42 at a position where the distance H between the rotation centers becomes long. It is provided. This positioning mechanism 1
8 is, for example, provided on one of the second support hole 36 and the bearing member 42 and the positioning projection 18a, and on the other,
Positioning recess 18b with which the positioning protrusion 18a is engaged
Consists of.

In the fifth embodiment, the second support hole 3
Since the shaft member 1b of the worm 1 is supported by the bearing member 42 that can be flexed within 6, the temperature of the reduction gear mechanism A portion becomes relatively higher than the room temperature at the time of assembly, and the humidity is high. When the tooth portion 21 expands because the humidity becomes relatively higher than that at the time of assembly, a pressing force in a direction opposite to the worm wheel 2 is applied to the worm 1, and the pressing force is further applied to the worm 1 and the rolling. It is added to the bearing member 42 via the bearing 7, the convex portion 42b of the bearing member 42 bends, and the shaft portion 1b fitted in the fitting hole 42a is moved in the radial direction so that the distance H between the rotation centers becomes longer. Can be biased. As a result, the distance H between the rotation centers of the worm 1 and the worm wheel 2 can be increased, and the worm 1 and the worm wheel 2
The torque applied to the meshing part of is shown by the solid line in Fig. 8 (1)
Can be reduced to the torque (2) shown by the broken line in FIG. 8, and the backlash amount can be corrected.

Further, since the shaft portion 1b of the worm 1 is supported by the bearing member 42 made of synthetic resin similar to the synthetic resin tooth portion 21, when the tooth portion 21 expands due to increase in humidity, this The bearing member 42 expands in the second support hole 36 at a ratio substantially equal to that of the tooth portion 21. A binding force is applied to the entire peripheral surface of the bearing member 42 by the reaction force of pressing against the support hole 36 due to this expansion. Since this binding force is smaller in the recess 41 than in the non-recessed portion, the bearing member 42 is deformed toward the recess 41, and the shaft portion fitted in the fitting hole 42a via the rolling bearing 7 is formed. 1b can be biased in the radial direction so that the distance H between the rotation centers becomes longer. As a result, the distance H between the rotation centers of the worm 1 and the worm wheel 2 can be increased, and the torque applied to the meshing portion can be changed from the torque (2) shown by the broken line in FIG. 8 to the torque (3 shown by the phantom line in FIG. ) And the amount of backlash can be further corrected.

An annular bearing member 42 having a recess 41 in a part of its peripheral surface is fitted and supported in the circular second support hole 36, and the distance H between the rotation centers becomes longer in the radial direction. Since the worm 1 can be bent, it is possible to support the worm 1 at an appropriate position without causing a center runout when the influence of the expansion of the tooth portion 21 is small.

Other configurations and operations are the same as those in the first and fourth embodiments.
Since they are similar, the same reference numerals are given to the similar parts, and the detailed description and the description of the function and effect are omitted.

Sixth Embodiment FIG. 9 is an enlarged sectional view of the essential parts of a sixth embodiment of the reduction gear mechanism. The reduction gear mechanism A of the sixth embodiment has a ring-shaped bearing having a recess 41 to be bent in the radial direction in the circular second support hole 36 instead of the bearing member 42 of the fifth embodiment. The member 43 is used.

In the sixth embodiment, the bearing member 43 is made of a similar synthetic resin material having a linear expansion coefficient similar to that of the tooth portion 21, and the fitting hole 43a into which the rolling bearing 7 is fitted. It has a torus shape. An elongated hole-shaped recess 41 is provided between a part of the outer peripheral surface of the bearing member 43 and the fitting hole 43a to be bent in the radial direction in which the distance H between the rotation centers becomes long. The inner wall portion 43b between the place 41 and the fitting hole 43a can be bent. The recess 41 penetrates over both ends of the bearing member 43, but may otherwise not penetrate.

In the sixth embodiment, the second support hole 3
Since the shaft portion 1b of the worm 1 is supported by the bearing member 43 that can be flexed within 6, the tooth portion 21 expands, and a pressing force in a direction opposite to the worm wheel 2 is applied to the worm 1. The inner wall portion 43b of the bearing member 43 bends,
The shaft portion 1b fitted in the fitting hole 43a via the rolling bearing 7 can be biased in the radial direction so that the distance H between the rotation centers becomes longer. As a result, the torque applied to the meshing portion can be reduced to torque (2) or torque (3) as shown in FIG. 8, and the backlash amount can be corrected.

Other configurations and operations are the same as in the first embodiment.
Since they are the same as those of Nos. 4 and 5, the same reference numerals are given to the same parts, and the detailed description thereof and the description of the function and effect will be omitted.

Embodiment 7 FIG. 10 is an enlarged cross-sectional view of the essential parts of Embodiment 7 of the reduction gear mechanism. The reduction gear mechanism A of the seventh embodiment has, instead of the bearing members 42 and 43 of the fifth and sixth embodiments, a recess 41 to be bent in the radial direction within the circular second support hole 36. An annular bearing member 44 is used.

In the seventh embodiment, the bearing member 44 has a fitting hole 44a into which the rolling bearing 7 is fitted by a similar synthetic resin material having a linear expansion coefficient similar to that of the tooth portion 21. It has an annular shape and a fitting hole 44
A concave portion 41 to be bent in the radial direction in which the distance H between the rotation centers is long is provided in a so as to be long in the circumferential direction, and a non-concave portion 44b connected to both ends in the longitudinal direction of the concave portion 41, 44b can be bent.

In the seventh embodiment, the second support hole 3
Since the shaft portion 1b of the worm 1 is supported by the bearing member 44 capable of bending within 6, the tooth portion 21 expands, and a pressing force in the opposite direction to the worm wheel 2 is applied to the worm 1. The non-recessed portions 44b, 44b connected to the recess 41 of the bearing member 44 are bent so that the shaft portion 1b fitted in the fitting hole 44a via the rolling bearing 7 has a longer distance H between the centers of rotation. It can be biased in the radial direction. As a result, the torque applied to the meshing portion is shown in FIG.
The torque (2) or the torque (3) can be reduced as shown by, and the backlash amount can be corrected.

Other configurations and operations are the same as those of the first embodiment.
Since they are the same as those of Nos. 4 and 5, the same reference numerals are given to the same parts, and the detailed description thereof and the description of the function and effect will be omitted.

Embodiment 8 FIG. 11 is an enlarged sectional view of the essential parts of Embodiment 8 of the reduction gear mechanism. In the reduction gear mechanism A of the eighth embodiment, instead of the fifth to seventh bearing members 42, 43, 44, a recess 41 to be bent in the radial direction in the circular second support hole 36 is provided. The bearing member 45 having an annular shape is used.

In the eighth embodiment, the bearing member 45 has a fitting hole 45a into which the rolling bearing 7 is fitted by a similar synthetic resin material having a linear expansion coefficient similar to that of the tooth portion 21. It has an annular shape, and a concave portion 41 to be bent in the radial direction in which the distance H between the rotation centers becomes long is curvedly provided in the outer peripheral surface so as to become long in the circumferential direction. Bottom wall 45 curved in a shape
It is possible to bend b.

In the eighth embodiment, the second support hole 3
Since the shaft member 1b of the worm 1 is supported by the bearing member 45 that can be flexed within 6, the tooth portion 21 expands and a pressing force in the opposite direction to the worm wheel 2 is applied to the worm 1. The bottom wall portion 45b of the bearing member 45 bends,
The shaft portion 1a fitted in the fitting hole 45a via the rolling bearing 7 can be biased in the radial direction so that the distance H between the rotation centers becomes longer. As a result, the torque applied to the meshing portion can be reduced to torque (2) or torque (3) as shown in FIG. 8, and the backlash amount can be corrected.

Other configurations and operations are the same as those of the first embodiment.
Since they are the same as those of Nos. 4 and 5, the same reference numerals are given to the same parts, and the detailed description thereof and the description of the function and effect will be omitted.

Embodiment 9 FIG. 12 is an enlarged cross-sectional view of the essential parts of Embodiment 9 of the reduction gear mechanism. The reduction gear mechanism A according to the ninth embodiment replaces the bearing members 42, 43, 44 and 45 according to the fifth to eighth embodiments with a concave portion to be bent in the radial direction within the circular second support hole 36. An annular bearing member 46 having a location 41 is used.

In the ninth embodiment, the bearing member 46 has a fitting hole 46a into which the rolling bearing 7 is fitted by a similar synthetic resin material having a linear expansion coefficient similar to that of the tooth portion 21. The outer peripheral surface is provided with a recess 41 to be bent in the radial direction in which the distance H between the rotation centers becomes long, and the bottom wall 46b of the recess 41 is formed. It can be bent.
The recess 41 is flat in the direction intersecting the radial direction.

Other configurations and operations are the same as in the first embodiment.
Since they are the same as those of Nos. 4 and 5, the same reference numerals are given to the same parts, and the detailed description thereof and the description of the function and effect will be omitted.

Embodiment 10 FIG. 13 is an enlarged cross-sectional view of the essential parts of Embodiment 10 of the reduction gear mechanism. The reduction gear mechanism A of the tenth embodiment is
Bearing members 42, 43, 44, 4 of Embodiments 5 to 9
Instead of 5, 46, a concave portion 41 to be bent in the radial direction in the circular second support hole 36, and a plurality of concave portions 47a, 47a which are circumferentially spaced apart from the concave portion 41.
The bearing member 47 having an annular shape is used.

In the tenth embodiment, the bearing member 47 has a fitting hole 47b into which the rolling bearing 7 is fitted by a similar synthetic resin material having a linear expansion coefficient similar to that of the tooth portion 21. It has an annular shape and has one recess 41 and two recesses 47a, 47a to be bent in the radial direction in which the distance H between the rotation centers is increased on the outer peripheral surface.
And are provided at substantially equal intervals in the circumferential direction, and the recess 4
The bottom wall portion 47c curved in the shape of a circular arc 1 can be bent.

In the tenth embodiment, since the shaft portion 1b of the worm 1 is supported by the bearing member 47 which can be flexed in the second support hole 36, the tooth portion 21 expands. , The pressing force in the opposite direction to the worm wheel 2 is applied to the worm 1, the bottom wall portion 47c of the bearing member 47 bends, and the shaft portion 1b fitted through the rolling bearing 7 into the fitting hole 47b is rotated. The distance H between centers can be biased in the radial direction so that the distance H becomes longer. As a result, as shown in FIG. 8, the torque applied to the meshing portion is torque (2),
Alternatively, the torque (3) can be reduced and the amount of backlash can be corrected.

Other configurations and operations are the same as in the first embodiment.
Since they are the same as those of Nos. 4 and 5, the same reference numerals are given to the same parts, and the detailed description thereof and the description of the function and effect will be omitted.

Eleventh Embodiment FIG. 14 is an enlarged cross-sectional view of the essential parts of the eleventh embodiment of the reduction gear mechanism. The reduction gear mechanism A of this Embodiment 11 is
Bearing members 42, 43, 44, 4 of Embodiments 5 to 10
Instead of 5, 46, 47, the circular second support hole 36
An annular bearing member 48 having a recess 41 inside which is to be bent in the radial direction is used.

In the eleventh embodiment, the bearing member 48 has a fitting hole 48a into which the rolling bearing 7 is fitted by a similar synthetic resin material having a linear expansion coefficient similar to that of the tooth portion 21. It has an annular shape, and a plurality of V-shaped recesses 41 to be bent in the radial direction in which the inter-rotation center distance H becomes longer are provided in the fitting hole 48a on the inner peripheral surface so as to be spaced apart in the circumferential direction. The protrusion 48b between the adjacent recesses 41 can be bent.

In the eleventh embodiment, since the shaft portion 1b of the worm 1 is supported by the bearing member 48 which can be flexed in the second support hole 36, the tooth portion 21 expands. , The pressing force in the opposite direction to the worm wheel 2 is applied to the worm 1, and the convex portion 48b of the bearing member 48 bends,
The shaft portion 1b fitted in the fitting hole 48a via the rolling bearing 7 can be biased in the radial direction so that the distance H between the rotation centers becomes longer. As a result, the torque applied to the meshing portion can be reduced to torque (2) or torque (3) as shown in FIG. 8, and the backlash amount can be corrected.

Other configurations and operations are the same as in the first embodiment.
Since they are the same as those of Nos. 4 and 5, the same reference numerals are given to the same parts, and the detailed description thereof and the description of the function and effect will be omitted.

Twelfth Embodiment FIG. 15 is an enlarged sectional view of the essential parts of a twelfth embodiment of the reduction gear mechanism. The reduction gear mechanism A according to the twelfth embodiment is
Bearing members 42, 43, 44, 4 of Embodiments 5 to 11
Instead of 5, 46, 47 and 48, an annular bearing member 49 having a recess 41 to be bent in the radial direction in the circular second support hole 36 is used.

In the twelfth embodiment, the bearing member 49 has a fitting hole 49a into which the rolling bearing 7 is fitted by a similar synthetic resin material having a linear expansion coefficient similar to that of the tooth portion 21. It has an annular shape and has one recess 41 and two recesses 49b, 49b to be bent in the radial direction in which the distance H between the rotation centers becomes long on the inner peripheral surface.
And are provided at substantially equal intervals in the circumferential direction, and the recess 4
The two non-recessed portions 49c, 49c facing 1 are made flexible.

In the twelfth embodiment, since the shaft portion 1b of the worm 1 is supported by the bearing member 49 which can be flexed in the second support hole 36, the tooth portion 21 expands. , The pressing force in the opposite direction to the worm wheel 2 is applied to the worm 1, and the two non-recessed portions 4 of the bearing member 49 are
9c and 49c bend, and the shaft portion 1b fitted in the fitting hole 49a via the rolling bearing 7 can be biased in the radial direction so that the distance H between the rotation centers becomes longer. As a result, the torque applied to the meshing portion can be reduced to torque (2) or torque (3) as shown in FIG. 8, and the backlash amount can be corrected.

Since other configurations and operations are similar to those of the eighth embodiment, similar parts are designated by the same reference numerals,
The detailed explanation and the explanation of the action and effect are omitted.

Embodiment 13 FIG. 16 is an enlarged cross-sectional view of the essential parts of Embodiment 13 of the reduction gear mechanism A, and FIG. 17 is a perspective view of a bearing member. In the reduction gear mechanism of the thirteenth embodiment, any one of the bearing members 42 to 49 of the fifth to twelfth embodiments has a shaft portion 1a of the worm 1,
It is designed to support 1b.

In the thirteenth embodiment, the bearing member 50 is fitted into each of the shaft portions 1a and 1b through the rolling bearings 6 and 7, and has two bearing cylindrical portions 50a which are equal to any of the bearing members 42 to 49. , 50b and the bearing tubular portion 50a,
A coupling portion 50c for coupling 50b, and fitting holes 50d, 50d inside the bearing tubular portions 50a, 50b, or
The recess 41 is provided on the outer peripheral surface. The bearing member 50 is formed of a similar synthetic resin material having a linear expansion coefficient similar to that of the tooth portion 21.
In addition, a third support hole 3 into which the bearing member 50 is fitted and supported is provided in a housing chamber that houses the worm 1 of the housing 3a.
7 is provided.

In the thirteenth embodiment, the shaft member 1a of the worm 1 is formed in the third support hole 37 by the bearing member 50.
Since 1b is supported, the tooth portion 21 expands, a pressing force in the direction opposite to the worm wheel 2 is applied to the worm 1, and the non-recessed portions 44b, 44b of the bearing member 50 are applied.
Etc. bend, and the fitting holes 50d, 50d are inserted through the rolling bearing 7.
The shaft portions 1a, 1b fitted in the shaft can be biased in the radial direction so that the distance H between the rotation centers becomes longer. As a result, the torque applied to the meshing portion can be reduced to torque (2) or torque (3) as shown in FIG. 8, and the backlash amount can be corrected.

Moreover, 2 for supporting the shaft portions 1a, 1b
Since the one bearing tubular portion 50a, 50b is integrally connected by the connecting portion 50c, the two bearing tubular portions 50a, 50b are
The positions of b with respect to the housing 3a can be made equal.

Other configurations and operations are the same as those of the first embodiment.
Since they are the same as 4, 5, and 7, similar parts are designated by the same reference numerals, and detailed description thereof and description of operational effects will be omitted.

In the embodiment described above, the worm 1 is biased in the radial direction by the rotation center distance changing means to change the rotation center distance H, but in addition, the worm wheel is changed by the rotation center distance changing means. 2 may be biased in the radial direction to change the distance H between the rotation centers. FIG. 18 is a sectional view showing another embodiment of the reduction gear mechanism and the electric power steering device.

In the reduction gear mechanism A and the electric power steering device of this embodiment, the fourth and fifth spaces are arranged in the housing chamber of the housing 3a for housing the worm wheel 2 in the axial direction of the transmission shaft 5. Supporting holes 38 and 39 are provided, and the rolling bearings 8 and 9 are fitted on both sides of the worm wheel 2 on the transmission shaft 5. One of the rolling bearings 8 arranged on the steered wheel 11 side is supported by the fourth support hole 38 via a bearing member 51 having the same shape as the bearing member 40 of the third embodiment, and arranged on the side opposite to the steered wheel side. The other rolling bearing 9 is fitted and supported in the circular fifth support hole 39.

The fourth support hole 38 is formed in a non-circular shape that is long in the direction in which the distance H between the rotation centers increases, and a fixing portion for fixing a part of the bearing member 51 on one side in the longitudinal direction. 38a.

The bearing member 51 is made of a similar synthetic resin material having a linear expansion coefficient similar to that of the tooth portion 21 and is fixed to the fixed portion 38a.
And a bearing part 51c having a fitting hole 51b into which the rolling bearing 8 is fitted and capable of being deformed in a direction opposite to the fixed part 51a by expansion.
The distance H between the rotation centers is set to be appropriate in the state where a is fixed to the fixed portion 38a. In addition, the bearing portion 5
Between the 1c and the fourth support hole 38, there is a space 52 which allows the deformation in the radial direction in which the distance H between the rotation centers of the bearing portion 51c becomes long. The amount of deformation of the bearing portion 51c depends on the clearance between the inner ring and the outer ring of the rolling bearing 9 and the rolling element, and the rolling bearings 8 and 9 of the transmission shaft 5.
The center of rotation of the worm wheel 2 is tilted due to the bending of the worm wheel 2, for example, 0 to 300 μm.

In this embodiment, since the transmission shaft 5 is supported by the bearing member 51 made of synthetic resin of the same type as the synthetic resin tooth portion 21, when the tooth portion 21 expands, The bearing member 5 is approximately equal in ratio to the tooth portion 21.
The bearing portion 51c of No. 1 expands in the space 52, and the rolling bearing 8
The transmission shaft 5 fitted in the fitting hole 51b through the can be biased so that the distance H between the rotation centers becomes longer in the radial direction, in other words, it can be bent. As a result, the distance H between the rotation centers of the worm 1 and the worm wheel 2 can be increased, and the backlash amount can be corrected to an appropriate value.

Since other configurations and operations are similar to those of the fourth embodiment, the same parts are designated by the same reference numerals,
The detailed explanation and the explanation of the action and effect are omitted.

The rotation center distance changing means for changing the rotation center distance H by biasing the worm wheel 2 in the radial direction as described above is the fifth embodiment.
It may be configured in the same manner as that of No. The means for changing the distance between the centers of rotation is provided on one side of the worm 1 or one side of the worm wheel 2 as described in the above embodiment, and also on both sides of the worm 1 or on the worm wheel 2. It may be provided on both sides, or may be provided on the worm side or the worm wheel side, or may be provided on both the worm and worm wheel sides.

Further, in the embodiment described above, the bearing members 42 to 51 have the shaft portion 1 through the rolling bearing 7 (6).
b (1a) or the rolling bearing 8 (9) is used to be fitted to the transmission shaft 5, but a sliding bearing may be used instead of the rolling bearings 7 (6) and 8 (9). Alternatively, any of the bearing members 42 to 51 may be fitted to the shaft portion 1b (1a) or the transmission shaft 5 without using a bearing.

The reduction gear mechanism A of the above-described embodiment has a small gear that is the worm 1 and a large gear that is the worm wheel 2, and is a small gear and a hypoid wheel that is a hypoid pinion. The structure may include a large gear, or may include a bevel gear.

[0108]

As described in detail above, according to the first and twelfth inventions, in the case where the backlash amount becomes excessively small due to the temperature and humidity of the reduction gear mechanism portion assembled at room temperature rising. The distance between the rotation centers of the small gear and the large gear can be increased, and the backlash amount can be corrected to an appropriate value. Also, the temperature of the reduction gear mechanism part,
When the backlash amount becomes excessive due to the decrease in humidity, the distance between the rotation centers can be shortened, and the backlash amount can be corrected to an appropriate value.

According to the second aspect of the invention, when the backlash amount becomes excessively small due to the temperature and humidity of the reduction gear mechanism part assembled at room temperature rising, the distance between the rotation centers is automatically lengthened. It is possible to correct the amount of backlash. Further, when the backlash amount becomes excessive due to the decrease in temperature and humidity of the reduction gear mechanism part, the distance between the rotation centers can be automatically shortened, and the backlash amount is corrected to an appropriate value. be able to.

According to the third invention, when the tooth portion made of synthetic resin expands and contracts, the connecting member automatically expands and contracts at a rate close to the expansion and contraction rate of the tooth portion. The distance between the centers of rotation can be automatically lengthened or shortened, and an appropriate amount of backlash can be automatically corrected.

According to the fourth aspect of the present invention, since the tooth portion of the large gear and the connecting member expand and contract at substantially the same ratio, it is possible to automatically correct the backlash amount to a more appropriate amount.

According to the fifth aspect, when the tooth portion expands due to moisture absorption over time and the backlash amount becomes too small, the backlash amount is corrected to an appropriate amount by the rotation center distance changing means of the support member. can do.

According to the sixth invention and the seventh invention, in the case where the gear can be supported at the proper position without the center runout, and the backlash amount becomes too small due to the time-dependent moisture absorption of the teeth. , Can be corrected to an appropriate amount of backlash.

According to the eighth aspect of the invention, the bearing portion can be favorably deformed in the space in accordance with the time-dependent moisture absorption of the gear.

According to the ninth aspect of the invention, the bearing member can be fixed at an appropriate position by fitting it into the support hole, and the bearing member can be easily assembled.

According to the tenth aspect of the invention, the bearing member automatically expands at a rate close to the expansion rate of the teeth, and the backlash amount can be corrected to an appropriate value.

According to the eleventh aspect of the invention, the distance between the centers of rotation can be changed on both sides of the gear, and moreover, the positions of the two tubular bearing portions with respect to the housing can be made equal.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a first embodiment of a reduction gear mechanism according to the present invention.

FIG. 2 is a transverse cross-sectional view of the first embodiment of the reduction gear mechanism according to the present invention.

FIG. 3 is a sectional view of an electric power steering device according to the present invention.

FIG. 4 is an enlarged cross-sectional view of a main part of a reduction gear mechanism according to a second embodiment of the present invention.

FIG. 5 is an enlarged cross-sectional view of a main part of a reduction gear mechanism according to a fourth embodiment of the present invention.

6 is an enlarged cross-sectional view taken along the line VI-VI of FIG.

FIG. 7 is an enlarged cross-sectional view of the essential parts of a reduction gear mechanism according to a fifth embodiment of the present invention.

FIG. 8 is a diagram showing the relationship between the amount of backlash and the torque applied to the mesh portion of the worm and the worm wheel.

FIG. 9 is an enlarged cross-sectional view of the essential parts of a sixth embodiment of a reduction gear mechanism according to the present invention.

FIG. 10 is an enlarged cross-sectional view of a main part of a reduction gear mechanism according to a seventh embodiment of the present invention.

FIG. 11 is an enlarged cross-sectional view of the essential parts of Embodiment 8 of a reduction gear mechanism according to the present invention.

FIG. 12 is an enlarged cross-sectional view of the essential parts of Embodiment 9 of a reduction gear mechanism according to the present invention.

FIG. 13 is a tenth embodiment of a reduction gear mechanism according to the present invention.
It is an expanded sectional view of the principal part of.

FIG. 14 is an eleventh embodiment of a reduction gear mechanism according to the present invention.
It is an expanded sectional view of the principal part of.

FIG. 15 is a twelfth embodiment of the reduction gear mechanism according to the invention.
It is an expanded sectional view of the principal part of.

FIG. 16 is a thirteenth embodiment of a reduction gear mechanism according to the present invention.
It is an expanded sectional view of the principal part of.

FIG. 17 is a perspective view of a bearing member of the reduction gear mechanism according to the present invention.

FIG. 18 is a sectional view showing another embodiment of the reduction gear mechanism and the electric power steering device according to the present invention.

FIG. 19 is a sectional view of a conventional electric power steering device.

FIG. 20 is a sectional view of a reduction gear mechanism portion of a conventional electric power steering device.

[Explanation of symbols]

1 Worm (Small Gear, Second Gear) 1b Shaft Part (Shaft) 2 Worm Wheel (Large Gear, First Gear) 21 Tooth Part 3 Housing 3a Housing (Supporting Member) 30a, 38a Fixed Part 31 First Housing Body 32 2nd housing body 36,37,38,39 Support hole 4 Motor 40,42,43,44,45,46,47,48,4
9, 50, 51 Bearing member (distance changing means between rotation centers) 40a, 51a Fixed parts 40b, 42a, 43a, 44a, 45a, 46a, 4
7b, 48a, 49a, 50d, 51b Fitting holes 40c, 51c Bearing portion 41 Recesses 42 to 51 Bearing member (rotation center distance changing means) 5 Transmission shaft (transmission means, shaft) 10 Connecting member (rotation center distance) Change means) 17 Space A Reduction gear mechanism H Distance between rotation centers

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H02K 7/116 H02K 7/116 (72) Inventor Masayoshi Sakuta 3-5-8 Minamisenba, Chuo-ku, Osaka-shi, Osaka No. Koyo Seiko Co., Ltd. (72) Inventor Kajuya Yoshioka 3-5-8 Minamisenba, Chuo-ku, Osaka-shi, Osaka Inside Koyo Seiko Co., Ltd. (72) Hideo Matsubara 3--5 Minamisenba, Chuo-ku, Osaka-shi, Osaka 8 Koyo Seiko Co., Ltd. (72) Inventor Koharu Minami 3-5-5 Minamisenba, Chuo-ku, Osaka-shi, Osaka Koyo Seiko Co., Ltd. (72) Kenki Okawa 3-5 Minamisenba, Chuo-ku, Osaka-shi, Osaka No. 8 F-term in Koyo Seiko Co., Ltd. (reference) 3D033 CA02 CA04 CA16 CA21 3J009 DA08 EA06 EA19 EA23 EA32 EB06 EB24 EC06 FA04 3J063 AA02 AB03 AC01 BA06 BA10 CA01 CB13 CD45 XC05 5H607 AA03 BB01 CC03 EE32 EE36 GG08 HH02

Claims (12)

[Claims] 1. A reduction gear mechanism including a small gear, a large gear meshing with the small gear, and a housing rotatably supporting the small gear and the large gear, wherein the housing supports the small gear. It is divided into a first housing body and a second housing body supporting the large gear, and the distance between the rotation centers of the small gear and the large gear can be changed between the first housing body and the second housing body. A reduction gear mechanism characterized by having a possible means for changing the distance between the rotation centers. 2. The rotation center distance changing means is the first
The reduction gear mechanism according to claim 1, comprising a connecting member that connects the housing body and the second housing body. 3. The large gear has a tooth portion made of synthetic resin that meshes with the small gear, and the rotation center distance changing means connects the first housing body and the second housing body with each other. The reduction gear mechanism according to claim 1, wherein the reduction gear mechanism comprises a coupling member made of metal. 4. The reduction gear mechanism according to claim 3, wherein the connecting member is made of a synthetic resin material similar to the tooth portion. 5. A first member, at least a tooth portion of which is made of synthetic resin.
Of the first gear, a second gear that meshes with the gear, and a support member that rotatably supports each of the first and second gears.
And a reduction gear mechanism having a rotation center distance changing means capable of changing the rotation center distance of the second gear. 6. The support member has a shaft coupled to the first or second gear and a housing in which the shaft is housed, and the rotation center distance changing means includes the shaft and the housing. The reduction gear mechanism according to claim 5, further comprising a bearing member interposed between the shafts and capable of being deformed in a radial direction in which the distance between the rotation centers becomes long. 7. The bearing member includes a fixed portion fixed to the housing, a fitting hole fitted to the shaft, and a bearing portion capable of being deformed in a direction opposite to the fixed portion. The reduction gear mechanism according to claim 6, further comprising: 8. The reduction gear mechanism according to claim 7, wherein a space is provided between the bearing portion and the housing to allow deformation of the bearing portion. 9. The reduction gear mechanism according to claim 7, wherein the housing has a support hole for supporting the bearing member, and the bearing member has a recess for bending in the support hole. . 10. The reduction gear mechanism according to claim 6, wherein the bearing member is made of synthetic resin. 11. The shaft is provided on both sides of the second gear, and the bearing member is provided with two bearing cylindrical portions fitted into each of the shafts and a coupling portion coupling the bearing cylindrical portions. With and
7. The reduction gear mechanism according to claim 6, wherein the bearing member is fitted inside the housing. 12. The reduction gear mechanism according to any one of claims 1 to 11, a steering assisting motor connected to the small gear or the second gear, and the large gear accompanying the rotation of the motor. An electric power steering device, comprising: a transmission unit configured to transmit a rotational force of a gear or the first gear to a steering mechanism.