JP2005069476A - Reduction gear mechanism and electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reduction gear mechanism and an electric power steering device capable of maintaining sufficient lubrication performance of grease. <P>SOLUTION: In this reduction gear mechanism, at least one gear is a cylindrical gear 3, and meshing is lubricated by grease 25. A surrounding part 16 having such shape that surrounds an outer peripheral part of the cylindrical gear 3 is provided on a housing 1 side. The surrounding part 16 is composed of first sections 16a inclined in such a way that an interval between the outer peripheral part of the cylindrical gear 3 and them is gradually reduced along the left and right directions of rotation, respectively, and a second section 16b which is nipped between the first sections 16a and in which an interval between the outer peripheral part of the cylindrical gear 3 and it becomes the minimum in a part continuous with the first sections 16a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a reduction gear mechanism that reduces and transmits the rotational force of a motor, and more particularly to a reduction gear mechanism of an electric power steering device that assists steering through a worm and a worm wheel.

  2. Description of the Related Art Conventionally, there has been known an electric power steering device that assists the rotational force of the steering shaft by transmitting the rotational force of the motor to the steering shaft by decelerating and boosting the rotational force of the motor. As the reduction gear mechanism, a gear reduction device such as a worm reduction device, a helical reduction device, a planetary gear reduction device, a hypoid bevel gear, or a bevel gear is generally used. For the lubrication of this gear reducer, grease with high viscosity is generally used.

  Lubrication is far superior to grease in terms of lubrication performance and heat transfer performance due to meshing, etc., but in order to prevent oil from leaking out of the reducer chamber, rotation on the drive side A sealing device such as an oil seal for sealing the shaft, the gear rotating shaft, and the driven gear rotating shaft is required. For this reason, sliding force is generated by sliding between the oil seal and the rotating shaft, and in particular, the rotating force on the drive shaft side is multiplied by the reduction ratio and transmitted to the driven shaft side, so that it is connected to the driven shaft. The steering feeling of the steering wheel operation becomes unacceptably large, and the steering feeling is deteriorated. For this reason, grease lubrication is used in a gear reducer of an electric power steering device for a passenger car.

  However, in the conventional reduction gear mechanism of the electric power steering apparatus, the grease lubricates the tooth surfaces by adhering to the gear tooth surfaces due to the viscosity, but the fluidity is very high due to the viscosity. bad. Even when grease is filled to fill the gear gap when the gear is assembled, most of the gear is pushed out of the gear gap due to the meshing of the gears, and only the grease slightly adhered to the tooth surface is lubricated. It contributes to. This is the same in all types of gear types described above, and the lubricating grease decreases with time, so that the lubricating grease becomes insufficient in the process of use, resulting in poor lubrication.

  In particular, in the worm speed reducer, because of slip transmission, once a poor lubrication occurs, the friction coefficient increases and heat generation increases, further deteriorating the poor lubrication, resulting in a sudden increase in wear. It will fall into a vicious circle.

  Therefore, in Patent Document 1, a worm is hollowed and a grease reservoir is provided, and a grease supply hole is provided in a meshing portion of the worm so that lubricating grease can be appropriately supplied from the grease supply hole.

  However, in order to make the worm hollow, it is necessary to increase the number of threads of the worm because of its strength retention. For this reason, the number of teeth of the worm wheel increases, resulting in an increase in the size of the device. There was a problem of end.

  Further, in Patent Document 2, a suppression portion for suppressing the scattering of grease due to the rotation of the worm is provided, and the grease pushed away in the worm tooth trace direction by the fan mounted on the worm is aerodynamically applied to the meshing portion. A worm speed reducer configured to push back is disclosed.

  In this meshing of the worm and the worm wheel, as shown in Patent Document 3, a contact surface appears in the tooth trace direction of the worm wheel tooth surface. Since this contact surface and the sliding direction by the rotation of the worm are substantially the same direction, the grease in the tooth space portion of the worm wheel moves so as to be taken out of the tooth width in the tooth trace direction of the worm wheel by the rotation of the worm. To do.

  However, in the above-mentioned Patent Document 2, there is a problem that the grease pushed out in the direction of the tooth trace of the worm wheel cannot be expected to be pushed back to the meshing portion, and the maintenance of the lubrication performance is insufficient.

Japanese Patent Laid-Open No. 2002-54696 (page 3, FIG. 2) JP 2002-147575 A (5th page, FIG. 8) JP 2001-270450 A (8th and 9th pages, FIGS. 7 to 9)

  The present invention improves the inconveniences of the above-described conventional example, and a reduction gear mechanism and electric power capable of maintaining sufficient lubrication performance of gears in meshing, particularly in gearing of a reduction gear of an electric power steering device. It is an object to provide a steering device.

  In order to achieve the above object, in the present invention, a reduction gear mechanism comprising a plurality of gears meshing with each other and transmitting rotation, and lubricating the meshing between these gears with grease, at least one gear of these gears as the gear rotates. A grease circulation mechanism that collects grease pushed out from the tooth gap and replenishes the gear is provided so as to be surrounded by a part of the outer peripheral portion of the gear.

  As a preferred form of the reduction gear mechanism according to the present invention, the at least one gear is a cylindrical gear, and the grease circulation mechanism includes an enclosure provided on a housing side of the plurality of gears, and the enclosure includes the enclosure Two first sections inclined so that the distance from the outer peripheral portion of the cylindrical gear gradually decreases along the left and right rotation directions, and a portion sandwiched between the two first sections and continuous thereto And a second section having a minimum distance from the outer peripheral portion of the cylindrical gear.

  In another aspect of the present invention, in order to decelerate the rotation of the electric motor, at least one of the plurality of gears incorporated in the housing is a cylindrical gear, and the deceleration that lubricates the meshing of the gear with grease. In the electric power steering apparatus having a gear mechanism, a surrounding portion having a shape surrounding the outer peripheral portion including both the side surfaces and the outer peripheral surface of the cylindrical gear is provided on the housing side, and the surrounding portion is connected to the outer peripheral portion of the cylindrical gear. A first section that is inclined so as to gradually decrease along the left and right rotation directions, and a portion that is sandwiched between and continues to the two first sections, and an outer peripheral portion of the cylindrical gear And a second section in which the interval between and is minimized.

  Further, at the end of the surrounding portion facing the both side surfaces of the cylindrical gear, a seal portion for slidingly contacting the both side surfaces to seal the grease in the surrounding portion is provided with the first section and the second section. The enclosure is provided over the section, and the surrounding portion is installed so as to be swingable within a predetermined range in the rotation direction of the cylindrical gear with respect to the housing.

  According to the present invention, the surrounding portion which is the grease circulation mechanism collects the grease pushed out from the gear tooth groove and replenishes the gear. However, every time the pushed-out grease passes through the surrounding portion, it is pushed out. Since the replenishment is repeated, the grease is sufficiently supplied to the gear, and the lubrication performance at the meshing portion is maintained in a good state.

  Further, in the electric power steering apparatus, if the surrounding portion is installed so as to be swingable within a predetermined range in the rotation direction of the cylindrical gear with respect to the housing, the predetermined range at the start of turning the steering wheel in a straight traveling state or the like is smoothly steered without a sense of resistance. This contributes to an improvement in steering feeling.

  An embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of a reduction gear mechanism of an electric power steering apparatus according to an embodiment of the present invention as viewed from the axial direction, and FIG. 2 is an axial cross-sectional view of the reduction gear mechanism of the electric power steering apparatus of FIG. 3 is a plan view showing the surrounding member, and FIG. 4 is a partially enlarged sectional view in the axial direction showing the reduction gear mechanism of FIG.

  1 and 2, an input shaft 6 connected to a steering wheel (not shown) and an output shaft 5 connected to a steering mechanism such as a rack and pinion mechanism (not shown) are coaxially connected by a torsion bar 7. ing. The torsion bar 7 is fitted into the input shaft 6 and the output shaft 5 and both ends thereof are fixed to the input shaft 6 and the output shaft 5 side, respectively. Thereby, the input shaft 6 and the output shaft 5 are elastically rotatable relative to each other.

  A worm wheel 3 is provided at a substantially central portion of the output shaft 5 at both inner and outer positions in the axial direction (hereinafter, the steering wheel side (right side in FIG. 2) in the axial direction is on the inside, and the opposite direction is called the outside). Four and nine inner rings are fitted and fixed respectively. The outer rings of the bearings 9 and 4 are fitted and fixed to a gear housing 100 and a housing cover 101 constituting the housing 1, respectively. That is, the output shaft 5 is rotatably attached to the housing 1 via the bearings 4 and 9. The housing cover 101 is shaped such that the bearing support portion 101b to which the outer bearing 4 is attached enters the hollow portion 3b of the worm wheel 3 in a non-contact manner.

  The worm wheel 3 is engaged with a worm 12 connected and fixed to a shaft 13a of an electric motor 13 for assisting steering. The shaft of the worm 12 is supported on the gear housing 100 side by bearings 20 and 21, and the electric motor 13 is attached to the gear housing 100.

  In the vicinity of the outer side surface of the worm wheel 3, an annular surrounding member 15 having a shape that partially surrounds the outer periphery of the worm wheel 3 is disposed on the gear housing 1 side.

A torque sensor 11 for detecting steering torque is disposed at a position adjacent to the inside of the bearing 9 inside the gear housing 100 (on the input shaft 6 side). The electric motor 13 is controlled mainly based on the steering torque detected by the torque sensor 11 based on the relative rotational displacement between the output shaft 5 and the input shaft 6.

  A ring-shaped groove 101a is provided on the worm wheel 3 side of the outer bearing 4 in the axial direction inner end side of the outer bearing 4 in the gear housing 100, and the bearing 4 is held in the groove 101a. A snap ring (C-RING) 2 is attached by fitting.

  As shown in FIG. 3, the surrounding member 15 has an annular shape, an outer annular portion 17 having a surrounding portion 16 as a grease circulation mechanism in a part thereof, and four protrusions 18 a for attaching to the inside of the housing cover 101. The outer annular portion 17 has an outer diameter smaller than that of the outer annular portion 17. The outer annular portion 17 and the inner annular portion 18 are concentrically connected by four elastic webs 19. It becomes the composition. The surrounding member 15 is fixed to the housing 1 by fitting the projection 18 a of the inner annular portion 18 into a hole 101 f (see FIG. 4) formed in the housing cover 101.

  These elastic webs 19 are made of resin or the like, and allow the outer annular portion 17 to elastically displace with respect to the inner annular portion 18 following the minute vibration of the worm wheel 3. The elastic web 19 may be formed integrally with the outer annular portion 17 and the inner annular portion 18 or may be fixed as a separate member.

  As shown in FIG. 1 (see also FIG. 9), the surrounding portion 16 is spaced from the outer peripheral portion including both side surfaces of the worm wheel 3 in the right and left rotational directions (right rotation: clockwise (CW)). , Counterclockwise (CCW)), the two first sections 16a, which are inclined so as to become gradually narrower, and a portion sandwiched between the two first sections 16a. The second section 16b is continuous with the second section 16b. The second section 16b is set to be parallel to the outer peripheral portion including both side surfaces of the wheel 3 and to have a minimum interval.

  As shown in FIG. 4 (see also FIG. 9), the surrounding portion 16 composed of the first section 16a and the second section 16b is opposite to the side of the worm wheel 3 from the side surface on which the outer annular portion 17 is located. It extends so as to surround up to the side surface of the wheel 3 and has a shape that sandwiches both side surfaces of the wheel 3 from the outside. Further, seal portions 16 c are formed over the first and second sections at both ends of the surrounding portion 16 facing both side surfaces of the wheel 3, and are in sliding contact with both side surfaces of the wheel 3.

  In the above configuration, when the tooth groove 3a of the worm wheel 3 meshes with the worm 12, the grease 25 of the tooth groove 3a is pushed out by the worm teeth toward the tooth trace of the tooth groove 3a of the wheel 3 as shown in FIG. Further, when the worm wheel 3 rotates and the grease 25 pushed out from the tooth gap 3a of the wheel 3 comes to the first section 16a of the surrounding portion 16, the distance between the side surface of the wheel 3 and the surrounding portion 16 gradually increases. Since it becomes narrower, the grease 25 is stored on the wheel 3 side immediately before the second section 16 b of the surrounding portion 16. At the same time, the accumulated grease 25 is dragged toward the gap between the second section 16 b and the side surface of the wheel 3 as the wheel 3 rotates.

  At this time, since the distance between the second section 16b and the side surface of the wheel 3 is minimized, the grease dragged in here is pushed again into the tooth gap 3a of the wheel 3 and is replenished. . Therefore, as shown in FIG. 1, the first section 16 a on the right side in the drawing of the surrounding portion 16 is for the left rotation (CCW) of the wheel 3, and the first section 16 a on the left side in the drawing is the wheel 3 of the wheel 3. This is provided for right rotation (CW).

  The accumulated grease 25 is prevented from leaking in the radial direction of the wheel 3 by the seal portion 16c.

  Thus, the grease 25 of the tooth gap 3a of the wheel 3 is pushed out at the meshing portion with the worm 12, and is resupplied to the tooth groove 3a of the wheel 3 when it comes to the surrounding portion 16, that is, the meshing portion and the surrounding portion. Extrusion and replenishment will be repeated each time it passes 16. Thereby, since the supply of the grease 25 to the worm wheel 3 is sufficiently performed, the lubrication performance at the meshing portion with the worm 12 can be maintained in a good state. At the same time, the grease is sufficiently kneaded by repeated extrusion and replenishment, so that deterioration of the grease can be suppressed.

  In the first embodiment, the surrounding portion 16 including the first section 16 a and the second section 16 b is provided in the surrounding member 15, which is a separate member from the housing 1, but is formed integrally with the housing 1. Also good.

  In addition, the second section 16b of the surrounding portion 16 is set such that the interval between the outer peripheral portion including both side surfaces of the wheel 3 is minimized, and the size of the interval is determined by the rotation of the wheel 3. At this time, it is desirable that the grease 25 is accumulated on the wheel 3 side immediately before the second section 16b, and the grease 25 is gradually dragged into the second section 16b.

  FIG. 6 is a cross-sectional view of the reduction gear mechanism of the electric power steering apparatus according to the second embodiment viewed from the axial direction.

  Next, a second embodiment will be described with reference to FIG. This embodiment is substantially the same as the first embodiment, and the same members are denoted by the same reference numerals, and duplicate descriptions thereof are omitted.

  In the figure, the difference from the first embodiment is that the surrounding portion 16 provided in the surrounding member 15 is positioned on both sides of the meshing portion of the worm wheel 3 and the worm 12, in other words, in the rotational direction of the wheel 3. It is the point provided in the front-back position of the meshing part.

  Even in this configuration, the same effect as that of the first embodiment can be expected. In particular, in the case of this embodiment, the grease pushed out from the tooth groove 3a of the wheel 3 at the meshing portion is in two places. Since it is replenished to the tooth gap 3a of the wheel 3 by the surrounding portion 16, it can be expected that the grease is replenished more reliably.

  7 is a cross-sectional view of the reduction gear mechanism of the electric power steering apparatus according to the third embodiment viewed from the axial direction, FIG. 8 is a plan view showing the surrounding member of FIG. 7, and FIG. 9 is the worm wheel and the surrounding in FIG. FIG. 10 is a partially enlarged sectional view in the axial direction showing the reduction gear mechanism of FIG. 7.

  Next, a third embodiment will be described with reference to FIGS. This embodiment is substantially the same as the second embodiment described above, and the same members are denoted by the same reference numerals, and duplicate descriptions thereof are omitted.

  In the figure, the difference from the second embodiment is that the surrounding member 15 can be swung within a predetermined range with respect to the housing 1.

  As shown in FIGS. 8 and 9, the surrounding member 15 includes an outer annular portion 17 having an annular shape and surrounding portions 16 at two locations, and a cylindrical inner cylindrical portion having an outer diameter smaller than the outer annular portion 17. The outer annular portion 16 and the inner tubular portion 22 are concentrically connected by three elastic webs 19.

  As shown in FIG. 10, the surrounding member 15 has an inner cylindrical portion 22 fitted in a swing guide portion 101c which is an annular groove formed in the housing cover 101 on the housing 1 side so as to be swingable in the circumferential direction. By doing so, it is attached to the housing 1. On the other hand, the gear housing 100 of the housing 1 that surrounds the worm wheel 3 (and the surrounding member 15) from the outside has an inner diameter set smaller than that of the second embodiment as shown in FIG. Are arranged closer to each other. Further, the gear housing 100 is provided with a swing allowing portion 101d whose inner diameter is set larger than that of the other portions only in a portion facing the two surrounding portions 16 and in the vicinity thereof. As a result, the surrounding portion 16 is fitted to the swing allowing portion 101d with a margin, so that the surrounding portion 16 is rotatable only in the range A in the circumferential direction of the wheel 3 and hits the stopper portion 101e after rotation. Oscillation is restricted by this.

  In steering operation, the steering feeling is better when there is no resistance in the fine steering state in the straight running state where the motor is hardly energized or when the steering wheel starts turning, and there is no sense of resistance. It is. However, if the sealing portion 16c is provided in the surrounding portion 16 as in the above embodiment, a sliding resistance is generated to some extent, so that the steering feeling is likely to deteriorate.

  Therefore, as in the third embodiment, by making the surrounding member 15 swingable within a predetermined range, the surrounding member 15 is caused by sliding friction at the seal portion 16c at the start of turning of the handle in a straight traveling state or the like. Although it rotates together with the worm wheel 3, when the surrounding portion 17 hits the stopper portion 101 e and the swinging is restricted, only the wheel 3 rotates while receiving (generating) the sliding resistance at the seal portion 16 c.

  Thus, the predetermined range at the start of turning the handle can be smoothly operated without a sense of resistance, and the generation of the sliding force at the seal portion 16c can be delayed after the power is energized by the motor. Even if it is provided, the steering feeling can be maintained in a good state.

  In the first embodiment, the surrounding portion 16 of the surrounding member 15 is disposed on the opposite side in the radial direction of the meshing portion of the wheel 3 with the worm 12, and in the second embodiment, the meshing portion of the wheel 3 is arranged. However, in short, in any rotation direction of the wheel 3, it is arranged so as to pass through the first section 16a and the second section 16b of the surrounding section 16 after passing through the meshing section. It ’s fine.

  FIG. 11 is a cross-sectional view of the reduction gear mechanism of the electric power steering apparatus according to the fourth embodiment viewed from the axial direction, and an axial cross-sectional view at each phase of the wheel. FIG. 12 is an electric power steering apparatus according to the fourth embodiment. FIG. 13 is a partially enlarged sectional view in the axial direction showing the reduction gear mechanism of FIG. 11.

  Next, a fourth embodiment will be described with reference to FIGS. In this embodiment, there are parts similar to those in the above-described embodiments, and the same members are denoted by the same reference numerals, and duplicate descriptions thereof are omitted.

  The fourth embodiment is different from the above-described embodiments in that the structure having the function of the surrounding portion 16 that is a grease circulation mechanism provided in the surrounding member 15 is provided on the inner peripheral surfaces of the gear housing 100 and the housing cover 101. In other words, the surrounding portion 16 is provided as a part of the housing 1 and the surrounding member 15 is not provided.

  As shown in FIGS. 11 and 12, the distance d <b> 1 between the inner peripheral surface of the gear housing 100 and the housing cover 101 that accommodates the worm wheel 3 and the outer peripheral surface of the wheel 3, and the distance d <b> 2 between the side surface of the wheel 3. Is the largest in the vicinity of the meshing portion of the wheel 3 and the worm 12 as shown in the phase sectional view A in the rotation direction of the wheel 3, and from this portion to the opposite side of the meshing portion of the wheel 3 (phase sectional diagram) This interval is gradually narrowed (as shown in B and D), and on the opposite side of 180 ° from the meshing portion, this interval is the narrowest as shown in phase sectional view C.

  Thus, as shown in FIG. 13, the distances d1 and d2 between the gear housing 100 and the housing cover 101 and the worm wheel 3 are in phase A, B, C and D in the rotational direction of the wheel 3. A (wave line) is maximum and phase C (solid line) is minimum, and phases B and D (two-dot chain lines) are intermediate sizes.

  Considering the first section and the second section provided in the surrounding portion 16 of each of the above embodiments, the gear housing 100 and the housing cover 101 from the vicinity of the phase B to the position immediately before the phase C and the phase D The section from the vicinity to the position immediately before phase C corresponds to the first section, and the portion of phase C corresponds to the second section. In the fourth embodiment, these sections of the gear housing 100 and the housing cover 101 serve as a grease circulation mechanism.

  Then, as shown in FIG. 12, the gear housing 100 and the housing cover 101 are spaced apart from the both side surfaces of the worm wheel 3 at a portion having the distances d1 and d2 such as the phases A, B, and D. In this manner, annular seal portions 100a and 101g projecting toward the wheel 3 are provided.

  In the above configuration, when the tooth groove 3a (see FIG. 1) of the worm wheel 3 meshes with the worm 12, as shown in FIG. 5, the grease 25 of the tooth groove 3a is caused by the teeth of the tooth groove 3a of the wheel 3 by the worm teeth. Extruded in the muscle direction. Further, when the worm wheel 3 rotates and the grease 25 pushed out from the tooth gap 3a of the wheel 3 approaches the phase C portion of the wheel 3 as shown in FIG. Since the distance between the cover 100 and the housing cover 101 is gradually narrowed, the grease 25 is collected on the wheel 3 side in the vicinity of the portion immediately before the phase C. At the same time, the accumulated grease 25 is dragged toward the narrow gap between the housing cover 101 and the side surface of the wheel 3 as the wheel 3 rotates.

  At this time, since the distance between the housing cover 101 and the side surface of the wheel 3 of phase C is minimized, the grease dragged in here is again pushed into the tooth gap 3a of the wheel 3 and replenished. Become. Therefore, as shown in FIG. 11, the portion of the wheel 3 from phase C to phase B is for the right rotation (CW) of the wheel 3, and the portion of the wheel 3 from phase C to phase D is the left rotation of the wheel 3. It has a structure for (CCW).

  Then, the grease 25 collected on the wheel 3 side in the vicinity of the portion immediately before the phase C is prevented from leaking in the radial direction of the wheel 3 by the seal portions 100a and 101g.

  Thus, the grease 25 of the tooth groove 3a of the wheel 3 is pushed out at the meshing portion with the worm 12, and is accumulated when it comes close to the phase C, and is replenished to the tooth groove 3a of the wheel 3, that is, Each time it passes through the meshing portion and the phase C portion, extrusion and replenishment are repeated. Thereby, since the supply of the grease 25 to the worm wheel 3 is sufficiently performed, the lubrication performance in the meshing portion of the wheel 3 and the worm 12 can be maintained in a good state. At the same time, the grease is sufficiently kneaded by repeated extrusion and replenishment, so that deterioration of the grease can be suppressed.

  In particular, in the fourth embodiment, since the housing 1 (the gear housing 100 and the housing cover 101) is provided with the structure having the function of the surrounding portion 16 in each of the above embodiments, it is not necessary to provide the surrounding member 15, and the parts Since the score can be reduced, it contributes to cost reduction.

  As described above in the four embodiments, according to the present invention, the surrounding portion including the outer peripheral portion including both the side surfaces and the outer peripheral surface of the cylindrical gear is provided on the housing side. A first section in which the distance from the outer peripheral portion gradually decreases along the left and right rotational directions, and a portion sandwiched between and continuous with the two first sections, And the second section in which the interval of the grease is minimized, the extrusion and replenishment are repeated each time the grease pushed out from the tooth space of the cylindrical gear passes through the enclosure, and the grease cylinder Since the supply to the gear is sufficiently performed, the lubrication performance of the grease at the meshing portion of the cylindrical gear is kept in a good state.

It is sectional drawing which looked at the reduction gear mechanism of the electric power steering device which shows the 1st Embodiment of this invention from the axial direction. It is an axial sectional view showing a reduction gear mechanism of the electric power steering device of FIG. It is a top view which shows the surrounding member of FIG. FIG. 2 is a partial enlarged view in the axial direction showing the reduction gear mechanism of FIG. 1. It is a perspective view which shows the adhesion state of the grease in the worm wheel of FIG. It is sectional drawing seen from the axial direction which shows the reduction gear mechanism of the electric power steering apparatus of 2nd Embodiment. It is sectional drawing seen from the axial direction which shows the reduction gear mechanism of the electric power steering apparatus of 3rd Embodiment. It is a top view which shows the surrounding member of FIG. It is a perspective view which shows the positional relationship of the worm wheel of FIG. 7, and a surrounding member. It is the elements on larger scale of the axial direction which shows the reduction gear mechanism of FIG. It is sectional drawing seen from the axial direction which shows the deceleration mechanism of the electric power steering apparatus of 4th Embodiment, and the axial sectional drawing in each phase of a wheel. It is an axial sectional view showing a reduction gear mechanism of the electric power steering device of FIG. FIG. 12 is a partial enlarged cross-sectional view in the axial direction showing the reduction gear mechanism of FIG. 11.

Explanation of symbols

1: Housing 3: Worm wheel (cylindrical gear)
5: output shaft 6: input shaft 12: worm 13: electric motor 15: surrounding member 16: surrounding portion 16a: first section 16b: second section 16c: seal portion 17: outer annular portion 18: inner annular portion 22 : Inner cylindrical portion 25: Grease 100: Gear housing 101: Housing cover

Claims (7)

In a reduction gear mechanism that consists of a plurality of gears that mesh with each other and transmit rotation, and lubricates the meshing between these gears with grease,
A speed reduction mechanism characterized in that a grease circulation mechanism that collects grease pushed out from a tooth groove of at least one gear of these gears and re-supplements the gear is provided so as to be surrounded by a part of the outer peripheral portion of the gear. Gear mechanism. The at least one gear is a cylindrical gear, and the grease circulation mechanism includes a surrounding portion provided on a housing side of the plurality of gears, and the spacing between the surrounding portion and the outer peripheral portion of the cylindrical gear is left and right Two first sections inclined so as to gradually decrease along the rotation direction, and a portion sandwiched between the two first sections and continuing to the first section, the distance from the outer peripheral portion of the cylindrical gear is The reduction gear mechanism according to claim 1, comprising a second section that is a minimum. In an electric power steering apparatus having at least one of a plurality of gears incorporated in a housing for decelerating the rotation of an electric motor and having a reduction gear mechanism that lubricates the meshing of the gears with grease,
An encircling portion surrounding the outer peripheral portion of the cylindrical gear is provided on the housing side, and the encircling portion is inclined so that a distance from the outer peripheral portion of the cylindrical gear gradually decreases along the left and right rotational directions. It consists of two first sections and a second section which is sandwiched between these two first sections and is continuous with the second section and has a minimum distance from the outer periphery of the cylindrical gear. Electric power steering device. 4. The electric power steering apparatus according to claim 3, wherein the cylindrical gear is a worm wheel. At the end of the surrounding portion that faces both side surfaces of the cylindrical gear, a seal portion that slides on both side surfaces and seals the grease in the surrounding portion extends over the first section and the second section. 5. The electric power steering apparatus according to claim 3, wherein the electric power steering apparatus is provided. 6. The electric power steering apparatus according to claim 3, wherein the surrounding portion is installed so as to be swingable within a predetermined range in the rotation direction of the cylindrical gear with respect to the housing. The electric power steering apparatus according to claim 3, 4, 5, or 6, wherein the surrounding portion is configured as a part of the housing.

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