JP6592219B1 - Steering device - Google Patents

Abstract

The steering device 1 is mounted on the housing 30 so as to cover a part of the rack shaft 3 and an opening formed in the housing 30, and is made of a resin in which a through hole for ventilation is formed. And a ventilation member 80 that is attached to a through hole formed in the cover 100 and ventilates between the internal space and the external space of the housing 30.

Description

  The present invention relates to a steering device.

Conventionally, in order to adjust the pressure inside the housing, a power steering device has been proposed in which a breathing valve is attached to a through hole formed in the housing.
For example, in the power steering device described in Patent Document 1, a measurement work hole for inserting a device for measuring the tension of the belt is formed through the housing case for housing the belt transmission mechanism. A breathing valve having a retainer and a breathing valve body that is held by the retainer and is formed so as to be able to transmit air in both directions is detachably attached to the hole.

Japanese Patent Laying-Open No. 2006-141277

In the power steering device, when the housing to which the ventilation member that ventilates between the inner space and the outer space of the housing is attached is a metal, for example, around the O-ring provided between the ventilation member and the housing. Water may accumulate and rust may develop. This rust reduces the sealing performance between the ventilation member and the housing, and water enters the interior of the housing from the gap between the O-ring and the housing or the gap between the O-ring and the ventilation member. There is a risk.
An object of the present invention is to provide a steering device that can prevent water from entering the inside of the housing due to adjusting the pressure inside the housing.

The present invention completed for this purpose includes a housing that covers a portion of the rack shaft and accommodates a worm wheel that constitutes a speed reduction portion together with a worm that is rotationally driven by an electric motor, and the housing. A resin cover that is mounted on the housing so as to cover the opened opening and has a through-hole for ventilation, and an inner space of the housing that is mounted on the through-hole formed in the cover. A ventilation member that ventilates between the outer space and the cover, the cover being fastened to the housing by a fastening member, and from the outermost surface in the fastening direction by the fastening member from the housing side a recess recessed in the recess in the steering apparatus is formed to be convex on the opposite side of the periphery the housing side of the through hole That.

  ADVANTAGE OF THE INVENTION According to this invention, the steering apparatus which can suppress that water permeates into the inside of a housing resulting from adjusting the pressure inside a housing can be provided.

1 is an overall configuration diagram of an electric power steering apparatus according to a first embodiment. It is sectional drawing of the II-II part of FIG. 1, and is sectional drawing of a transmission mechanism part. It is sectional drawing of the III-III part of FIG. 1, and is sectional drawing of an assist part. It is sectional drawing in the rotating shaft center of a worm | warm. It is an enlarged view of the V section of FIG. (A) is the figure which looked at the assist cover which concerns on 2nd Embodiment in the axial center direction of a pinion shaft. (B) is sectional drawing of the VIb-VIb part of (a). It is the figure which looked at the assist cover which concerns on 3rd Embodiment in the axial direction. It is sectional drawing of the assist cover which concerns on 4th Embodiment.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
<First Embodiment>
FIG. 1 is an overall configuration diagram of an electric power steering apparatus 1 according to the first embodiment.
FIG. 2 is a cross-sectional view taken along the line II-II of FIG.
3 is a cross-sectional view taken along the line III-III in FIG.
FIG. 4 is a cross-sectional view at the rotational axis of the worm.
FIG. 5 is an enlarged view of a portion V in FIG.

  An electric power steering device (hereinafter also referred to as “steering device”) 1 according to the first embodiment is a steering device for arbitrarily changing the traveling direction of a vehicle as shown in FIG. The steering device 1 is a so-called double pinion type power steering device.

  The steering device 1 includes tie rods (not shown) connected to left and right wheels (not shown) as rolling wheels via knuckle arms (not shown), and a rack shaft 3 connected to the tie rods. . In addition, the steering device 1 includes a transmission mechanism unit 10 that transmits a steering force from a steering wheel (not shown) provided in the vehicle to the rack shaft 3. In addition, the steering device 1 includes an electric motor 50 and includes an assist unit 20 that assists the movement of the rack shaft 3 by transmitting the driving force of the electric motor 50 to the rack shaft 3 as a steering assist force.

The steering device 1 includes a housing 30 that covers a part of the outer peripheral surface of the rack shaft 3, supports the rack shaft 3 so as to be movable in the axial direction, and supports the electric motor 50. The housing 30 includes a rack housing 31 as an example of a first housing that houses a part of the rack shaft 3, and a transmission housing 32 that covers the periphery of the torque sensor 14 described later. In addition, the housing 30 includes an assist housing 33 as an example of a second housing that covers a periphery of a speed reduction portion 60 described later and includes a support portion 330 that supports the electric motor 50.
Further, the steering device 1 includes a transmission cover 34 that covers the opening of the transmission housing 32, and an assist cover 100 that covers the opening of the assist housing 33.

  The rack housing 31 has legs 311 that are fixed to a vehicle body (not shown) of the vehicle. The leg 311 is formed with a through hole through which a bolt (not shown) used when being fixed to a vehicle body (not shown). In the steering device 1, a surface of the leg 311 opposite to a direction in which an input shaft 12 that will be described later projects is a mounting seat surface that is placed on the vehicle body when fixed to the vehicle body, and the vertical direction of the vehicle body 1 is fixed to the vehicle main body so that the lower side is the lower side shown in FIG. 1 and the upper side in the vertical direction is the upper side shown in FIG. In addition, dust boots 4 are attached to both ends of the rack housing 31 in the axial direction of the rack shaft 3. The transmission housing 32 is fixed to the rack housing 31 with bolts (not shown), and the transmission cover 34 is fixed to the transmission housing 32 with bolts. The assist housing 33 is fixed to the rack housing 31 with bolts (not shown), and the assist cover 100 is fixed to the assist housing 33 with bolts 102.

As shown in FIG. 2, the transmission mechanism unit 10 includes a pinion shaft 11 on which a pinion 11 a that forms a rack and pinion together with a rack 3 a formed on the rack shaft 3, and a steering wheel (not shown). And an input shaft 12 to which a steering force is input. Further, the transmission mechanism unit 10 includes a torsion bar 13 connected to the pinion shaft 11 and the input shaft 12, and a torque sensor 14 that detects the steering torque of the steering wheel based on the amount of twist of the torsion bar 13. Yes.
Each of the rack housing 31 and the transmission housing 32 includes a bearing 31 a and a bearing 32 a that rotatably support the pinion shaft 11. The transmission cover 34 has a bearing 34 a that rotatably supports the input shaft 12.
The transmission mechanism unit 10 includes a rack guide 40 that presses the rack 3a of the rack shaft 3 against the pinion 11a of the pinion shaft 11 and supports the rack shaft 3 slidably.

As shown in FIGS. 3 and 4, the assist unit 20 includes a pinion shaft 21 on which a pinion 21 a that forms a rack-and-pinion is formed together with a rack 3 b formed on the rack shaft 3. The assist unit 20 includes an electric motor 50, a speed reduction unit 60 that reduces the rotational speed of the electric motor 50, and a shaft coupling 70 that transmits the rotational driving force of the electric motor 50 to the speed reduction unit 60.
Each of the rack housing 31 and the assist housing 33 includes a bearing 31b and a bearing 33a that rotatably support the pinion shaft 21.

The assist unit 20 includes a rack guide 45 that presses the rack 3b of the rack shaft 3 against the pinion 21a of the pinion shaft 21 and supports the rack shaft 3 slidably.
The assist unit 20 includes a ventilation member 80 that is attached to the assist cover 100 and allows gas to flow between the outside (outside) of the housing 30 and the inside (inside) of the housing 30. .

The speed reduction unit 60 includes a worm wheel 61 that constitutes a worm gear, and a worm 62 that is a cylindrical worm that is a screw-shaped gear. The worm wheel 61 is held by the pinion shaft 21.
The shaft coupling 70 includes a metal motor-side member 71 held by the output shaft 51 of the electric motor 50, a metal worm-side member 72 held by the worm 62 of the speed reduction unit 60, the motor-side member 71, and the worm. A rubber elastic member 73 interposed between the side member 72 and the side member 72 is provided.

The electric motor 50 is a well-known brushless motor, and as shown in FIG. 4, the magnet 52 mounted on the output shaft 51, the iron core 53, the winding 54, and the magnet 52, the iron core 53 and the winding 54 are accommodated. And a frame 55. The electric motor 50 includes a bracket 56 that holds the frame 55 and is fastened to the support portion 330 of the assist housing 33. Each of the frame 55 and the bracket 56 includes a bearing 57 and a bearing 58 that rotatably support the output shaft 51.
The electric motor 50 is supported by the assist housing 33 when the bracket 56 is fastened to the support portion 330 of the assist housing 33.

(Ventilation member 80)
As shown in FIG. 5, the ventilation member 80 has a ventilation film 81 that allows gas to flow between the internal space of the housing 30 and the external space of the housing 30. The ventilation member 80 has a holding body 82 that holds the ventilation film 81 and is attached to an insertion hole 121 as an example of a through hole formed in the assist cover 100. Further, the ventilation member 80 has a membrane cover 83 that protects the ventilation membrane 81. In addition, the ventilation member 80 includes an O-ring 84 that is disposed between the holding body 82 and the assist cover 100 and seals a gap between the holding body 82 and the assist cover 100.

  The holding body 82 has a cylindrical portion 821 having a cylindrical shape. Hereinafter, the direction of the center line C of the cylindrical portion 821 may be referred to as a center line direction. 5 may be referred to as one side in the center line direction, and the upper side in FIG. 5 may be referred to as the other side in the center line direction. One side in the center line direction is inside the housing 30 (assist housing 33), and the other side in the center line direction is also outside the housing 30 (assist housing 33).

  The holding body 82 has an inward portion 822 that extends from one end of the cylindrical portion 821 toward the center line C, and an insertion portion that protrudes from the inward portion 822 to the one side and is inserted into the insertion hole 121 of the assist cover 100. 823. A communication hole 824 that connects the inside and the outside of the housing 30 is formed in the center portion of the holding body 82 by passing through the inward portion 822 and the insertion portion 823.

A concave portion 821 a that is recessed inward from the outer peripheral surface is formed at the other end of the cylindrical portion 821. The holding body 82 holds the membrane cover 83 by fitting an inner protrusion 833 (described later) of the membrane cover 83 into the recess 821a. In addition, a communication hole 821b that connects the inside and the outside of the cylindrical portion 821 is formed at the other end of the cylindrical portion 821.
The inward portion 822 has a holding portion 822 a that protrudes to the other side at a portion on the cylindrical portion 821 side and holds the gas permeable membrane 81.

The insertion portion 823 has an outer protruding portion 823a that protrudes outward in the radial direction from the outer surface at the tip end (one side) where insertion starts in the insertion hole 121 of the assist cover 100. The outer protrusions 823a are provided at two equal intervals in the circumferential direction. Further, a portion of the insertion portion 823 where the outer protrusion 823a is not provided has a recess 823b from the distal end toward the other side.
It can be exemplified that the material of the holding body 82 is a resin. The molding method of the holding body 82 is not particularly limited, and examples thereof include injection molding, compression molding, and cutting.

The membrane cover 83 includes a disc-shaped top portion 831, a cylindrical cylindrical portion 832 extending from the outermost peripheral portion of the top portion 831 to one side (the holding body 82 side), and an end portion on one side of the cylindrical portion 832. And an inner projecting portion 833 projecting inward.
The outer diameter of the top 831 is larger than the outer diameter of the gas permeable membrane 81, and the top 831 covers the gas permeable membrane 81 at a position spaced from the gas permeable membrane 81 by a predetermined distance.
The inner protruding portion 833 is fitted into a recess 821 a formed in the cylindrical portion 821 of the holding body 82.
By covering the gas permeable membrane 81 with the membrane cover 83, damage to the gas permeable membrane 81 due to an external force, and accumulation of sand, mud, or the like on the surface of the gas permeable membrane 81 are suppressed.
It can be exemplified that the material of the membrane cover 83 is a resin.

The ventilation film 81 is a disk-shaped film having a function of suppressing moisture and mud from entering from the outside while having air permeability. The outer diameter of the gas permeable membrane 81 is larger than the diameter of the communication hole 824 formed in the holding body 82, and is held by the holding portion 822 a of the holding body 82 so as to cover the communication hole 824. Examples of the holding method include welding the gas permeable membrane 81 to the holding portion 822a and bonding with an adhesive or a double-sided tape.
The material, structure, and form of the gas permeable membrane 81 are not particularly limited, but can be exemplified as a Gore (registered trademark) membrane.

(Assist cover 100)
As shown in FIG. 5, the assist cover 100 is a disk-shaped member formed of resin, and is fastened to the assist housing 33 with a bolt 102 as an example of a tightening member, thereby opening the assist housing 33. Cover part 331. Hereinafter, the inside of the assist housing 33 may be referred to as “inside” and the outside of the assist housing 33 may be referred to as “outside”.

The assist cover 100 has a ring shape, and includes a contact portion 110 that contacts an outer end face of the assist housing 33 and an annular bottom portion 120 provided inside the contact portion 110.
The contact portion 110 is formed with two tightening holes 111, which are through-holes for passing bolts, symmetrically with respect to the center of the contact portion 110. The center of the contact portion 110 is also the center of the assist cover 100, and the center of the assist cover 100 is mounted so as to be the same as the axis of the pinion shaft 21.
The bottom 120 is formed with an insertion hole 121 into which the ventilation member 80 is inserted at the center position. The hole diameter of the insertion hole 121 gradually decreases from the outside toward the inside.

  In addition, the assist cover 100 is configured so that the bolt 102 is tightened in the tightening direction (pinion shaft 21) so as to connect the outer and center end portions of the contact portion 110 and the outer and outer diameter end portions of the bottom portion 120. The inclined surface 130 is inclined with respect to the axial center direction and the center line direction). Further, the assist cover 100 includes a rib 140 having an angle larger than the inclination angle of the inclined surface 130 so as to connect the central portion of the contact portion 110 and the outer surface (bottom surface) of the bottom portion 120. Yes. A plurality of ribs 140 (eight in the example shown in FIG. 1) are provided around the insertion hole 121 at equal intervals in the circumferential direction. Two ribs 140 among the plurality of ribs 140 are each formed on a line connecting the center of the fastening hole 111 of the contact part 110 and the center of the insertion hole 121 of the bottom part 120.

  Further, the assist cover 100 includes an outer peripheral surface 150 that faces the inner peripheral surface 332 at the outer end of the assist housing 33, and a concave portion 160 that is recessed from the outer peripheral surface 150 toward the center. An O-ring 170 that seals the gap between the assist cover 100 and the assist housing 33 is fitted in the recess 160.

  Since the assist cover 100 has the shape described above, the assist cover 100 is a recess recessed from the outer surface (outermost surface) of the contact portion 110, which is the outermost surface in the tightening direction by the bolt, to the assist housing side (inner side). 180.

In the assist cover 100 configured as described above, the bolt 102 passed through the tightening hole 111 formed in the contact portion 110 in a state where the outer peripheral surface 150 is fitted inside the inner peripheral surface 332 of the assist housing 33. And tightened to the assist housing 33.
And the insertion part 823 provided in the holding body 82 of the ventilation member 80 is inserted into the insertion hole 121 formed in the bottom part 120 from the outside. Then, after the insertion portion 823 of the ventilation member 80 is elastically deformed, the outer protruding portion 823a returns so as to be larger than the hole diameter of the insertion hole 121 at a position inside the inner surface of the bottom portion 120 of the assist cover 100. To do. That is, the insertion portion 823 of the ventilation member 80 is inserted into the insertion hole 121 formed in the bottom portion 120 while being elastically deformed, and has an outer protrusion 823a as an example of a claw portion that is hooked on the inner surface of the bottom portion 120. Have. Thereby, it is suppressed that the ventilation member 80 moves outside with respect to the assist cover 100 and falls off.

  The size of the portion of the ventilation member 80 that protrudes outward from the insertion hole 121 is set such that the ventilation member 80 is accommodated in the recess 180 in a state where the ventilation member 80 is attached to the assist cover 100. That is, the outer diameters of the holding body 82 and the membrane cover 83 of the ventilation member 80 are smaller than the diameters of the end portions on the outer diameter side of the bottom 120. The distance L80 from the outer surface (bottom surface) of the bottom portion 120 to the outer surface of the membrane cover 83, which is the height of the outer surface of the membrane cover 83 of the ventilation member 80, is the outer surface (bottom surface) of the bottom portion 120. ) To the outer surface (outermost surface) of the contact portion 110 is smaller than the distance L100.

(Function / Function)
In the steering apparatus 1 configured as described above, the ventilation member 80 is attached to the assist cover 100, so that scattered matter such as moisture, mud or dust enters from the outside to the inside of the assist housing 33. While suppressing, the pressure change accompanying the temperature change inside the housing 30 is suppressed.

Specifically, the inside of the assist housing 33 is continuous with the inside of the rack housing 31 that houses a part of the rack shaft 3 and the inside of the transmission housing 32 that covers the periphery of the torque sensor 14. Further, the inside of the rack housing 31 is continuous with the inside of the dust boots 4 provided at both ends of the rack shaft 3.
When the steering device 1 is used in a low-pressure and high-temperature environment where the atmospheric pressure is low and high, for example, at high altitudes, the volume of air in the housing 30 and the dust boot 4 increases, and the dust boot 4 may swell. Further, if the interior of the housing 30 generates heat due to energization of the winding 54 of the electric motor 50 or friction caused by the operation of the speed reduction unit 60, the air inside the housing 30 may expand and the dust boot 4 may expand. The swelled dust boot 4 can apply resistance to the movement of the rack shaft 3.

  However, according to the steering apparatus 1 according to the present embodiment, the ventilation member 80 discharges the air inside the housing 30 to the outside through the communication hole 824, the ventilation film 81, and the communication hole 821b. Thereby, it is suppressed that the swelled dust boot 4 applies resistance to the rack shaft 3. Further, when the pressure inside the housing 30 becomes larger than the pressure outside the housing 30 due to the expanded air, the air inside the housing 30 is released to the outside of the housing 30 through the ventilation member 80. For example, air is suppressed from being released from a gap between the rack housing 31 and the assist housing 33, a gap between the assist housing 33 and the assist cover 100, or the like.

On the other hand, when the energization of the winding 54 of the electric motor 50 or the operation of the speed reduction unit 60 stops, the air inside the housing 30 contracts. Then, the pressure inside the housing 30 becomes negative with respect to the pressure outside the housing 30, and the air outside the housing 30 is drawn into the housing 30 through the ventilation member 80.
The ventilation film 81 of the ventilation member 80 prevents liquid and solid from entering the inside of the housing 30 from the outside of the housing 30 when air outside the housing 30 is guided to the inside of the housing 30. Therefore, the ventilation member 80 prevents water, dust, and the like from entering the housing 30.

As described above, according to the steering apparatus 1, by providing the assist cover 100 with the ventilation member 80, the air inside the entire housing 30 is discharged to the outside or the outside air is sucked into the inside by one ventilation member 80. It becomes possible to do. Then, according to the steering apparatus 1, the ventilation member 80 that functions in this manner is attached to the assist cover 100 that covers the opening 331 formed in the assist housing 33 having the support portion 330 that supports the electric motor 50. Therefore, it is possible to suppress a pressure change in the internal space of the assist housing 33 in the vicinity of the electric motor 50 that generates heat and in which air that easily expands and contracts exists.
Further, since the ventilation member 80 is fitted in the assist cover 100 and is housed in the recess 180, scattered objects from the road surface side are unlikely to adhere to the ventilation member 80.

The material of the holding body 82 and the membrane cover 83 of the ventilation member 80 is resin, and the material of the assist cover 100 is also resin. Therefore, even if water accumulates around the ventilation member 80, for example, in the gap between the holding body 82 of the ventilation member 80 and the assist cover 100, rust does not advance.
Further, the surface roughness of the insertion hole 121 in the bottom 120 of the assist cover 100 is used to prevent water from entering the gap between the support 82 of the ventilation member 80 and the assist cover 100 using the O-ring 84. It can be formed by injection molding using a resin having a sufficiently small size. For example, the assist cover 100 can be injection-molded using a fixed mold and a movable mold that moves in the center line direction with respect to the fixed mold, and the insertion hole 121 can be molded using the movable mold. Therefore, according to the assist cover 100, for example, the member to which the ventilation member 80 is attached is molded by aluminum die casting, and the surface of the hole into which the ventilation member 80 is inserted must be machined. The manufacturing cost of the cover 100 can be reduced.

<Second Embodiment>
FIG. 6A is a view of the assist cover 200 according to the second embodiment when viewed in the axial direction of the pinion shaft 21. FIG.6 (b) is sectional drawing of the VIb-VIb part of Fig.6 (a).
The assist cover 200 according to the second embodiment differs from the assist cover 100 according to the first embodiment in that an outer peripheral wall 290 is provided around the ventilation member 80. Hereinafter, differences from the assist cover 100 will be described. Parts having the same shape and function in the assist cover 200 and the assist cover 100 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 6, the assist cover 200 according to the second embodiment has an outer peripheral wall 290 that protrudes outward from the bottom 120 and covers the periphery of the outer peripheral surface of the holding body 82 and the membrane cover 83 of the ventilation member 80. Have. It can be exemplified that the height of the outer peripheral wall 290 from the bottom 120 is the same as the height to the outer surface of the membrane cover 83 of the ventilation member 80. The outer peripheral wall 290 is formed with a notch 291 that is recessed from the tip so that the height from the bottom 120 is lower than the other portions in the circumferential direction. In the assist cover 200 according to the second embodiment, the portion where the notch 291 is formed is the lower side in the vertical direction of the insertion hole 121 in which the ventilation member 80 is mounted. Further, the width (circumferential length) at the portion where the notch 291 is formed can be exemplified as being a dimension that does not allow the operator's finger to enter, for example, about 10 mm or less. In addition, the height from the bottom part 120 of the site | part in which the notch 291 is formed may be zero.

In the assist cover 200 configured as described above, since the outer peripheral wall 290 is provided around the ventilation member 80, an operator does not intend the ventilation member 80 when the steering device 1 is mounted on the vehicle. Touching and the ventilation member 80 being prevented from falling off the assist cover 200 due to external force are suppressed. In particular, in the configuration in which the outer protruding portion 823a of the insertion portion 823 is attached by being hooked on the inner surface of the bottom portion 120 as in the ventilation member 80, for example, as compared with a configuration in which it is fixed by adhesion or the like. Although the ventilation member 80 can be easily detached, the outer peripheral wall 290 prevents the ventilation member 80 from coming off.
Further, the outer peripheral wall 290 prevents water and mud that are scattered matter from reaching the communication hole 821 b formed in the holding body 82 of the ventilation member 80.

Further, according to the assist cover 200, even if water or mud reaches between the ventilation member 80 and the outer peripheral wall 290, the notch 291 formed on the lower side in the vertical direction with respect to the ventilation member 80 causes water And accumulation of mud is suppressed. As a result, it is possible to prevent the air and mud collected between the ventilation member 80 and the outer peripheral wall 290 from hindering the ventilation through the communication hole 821b formed in the ventilation member 80.
Further, the assist cover 200 can be easily formed by injection molding using a resin.

<Third Embodiment>
FIG. 7 is an axial view of the assist cover 300 according to the third embodiment.
The assist cover 300 according to the third embodiment is different from the assist cover 200 according to the second embodiment in an outer peripheral wall 390 corresponding to the outer peripheral wall 290. Hereinafter, differences from the assist cover 200 will be described. Parts having the same shape and function in the assist cover 300 and the assist cover 200 are denoted by the same reference numerals, and detailed description thereof is omitted.

The outer peripheral wall 390 of the assist cover 300 according to the third embodiment has a notch 391 that is recessed from the tip so that the height from the bottom 120 is lower than other parts in the circumferential direction. Two are formed symmetrically with respect to the center of the insertion hole 121 in which is inserted. One notch 391 of the two notches 391 is on the lower side in the vertical direction of the insertion hole 121, similarly to the notch 291 in the assist cover 200 according to the second embodiment. The other notch 391 of the two notches 391 is on the upper side in the vertical direction of the insertion hole 121. Further, a line connecting the centers of the fastening holes 111 of the two contact portions 110 and a line connecting the circumferential centers of the two notches 391 are orthogonal to each other when viewed in the axial direction. That is, in the assist cover 300 according to the third embodiment, whichever of the two tightening holes 111 formed in the contact portion 110 is matched with either of the two female screws formed in the assist housing 33. The bolt 102 can be tightened. That is, the assist cover 300 has no direction with respect to the assist housing 33.
As a result, according to the assist cover 300 according to the third embodiment, in addition to the effect of the assist cover 200 according to the second embodiment, the effect that the assist cover 300 can be easily assembled to the assist housing 33. Have

<Fourth Embodiment>
FIG. 8 is a cross-sectional view of the assist cover 400 according to the fourth embodiment.
The assist cover 400 according to the fourth embodiment is different from the assist cover 100 according to the first embodiment in a bottom portion 420 corresponding to the bottom portion 120. Hereinafter, differences from the assist cover 100 will be described. Parts having the same shape and function in the assist cover 400 and the assist cover 100 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 8, the bottom part 420 of the assist cover 400 according to the fourth embodiment is formed so that the center part is convex outward (the other side). That is, the bottom portion 420 includes a ring-shaped outer diameter portion 421 that is a portion on the outer diameter side, and a ring-shaped peripheral portion 422 provided around the insertion hole 121. The bottom 420 is provided so as to connect the outer diameter part 421 and the peripheral part 422, and the outer diameter part 421 is located so that the central part is located on the outer side (the other side) than the outer diameter part. An inclined portion 423 that is inclined with respect to the axial direction of the pinion shaft 21 from an end portion on the central side to an end portion on the outer diameter side in the peripheral portion 422.

  As described above, the assist cover 400 is fastened to the housing 30 with the bolts 102 and has the recesses 180 that are recessed from the outermost surface in the fastening direction by the bolts 102 toward the housing 30 (inner side). The recess 180 is formed so that the periphery of the through hole 121 is convex on the side (outside) opposite to the housing 30 side. According to the assist cover 400 configured in this manner, even if water or mud reaches the periphery of the ventilation member 80, the periphery of the ventilation member 80 is formed to be convex outward (the other side). Therefore, accumulation of water and mud around the ventilation member 80 is suppressed. As a result, it is possible to prevent the air and mud reaching the ventilation member 80 from interfering with the ventilation through the communication hole 821b formed in the ventilation member 80.

  The assist cover 400 according to the fourth embodiment has an outer peripheral wall 290 included in the assist cover 200 according to the second embodiment or the assist cover 300 according to the third embodiment around the ventilation member 80. You may have the outer peripheral wall 390 which has. Thereby, when the steering device 1 is mounted on the vehicle, an operator can avoid unintentionally touching the ventilation member 80, or the ventilation member 80 can be prevented from falling off the assist cover 400 due to external force. It becomes possible. Further, it is possible to prevent water and mud that are scattered matter from reaching the communication hole 821b formed in the holding body 82 of the ventilation member 80.

DESCRIPTION OF SYMBOLS 1 ... Steering device, 3 ... Rack shaft, 4 ... Dust boot, 10 ... Transmission mechanism part, 20 ... Assist part, 30 ... Housing, 31 ... Rack housing, 32 ... Transmission housing, 33 ... Assist housing, 50 ... Electric motor, 80 ... Ventilation member, 100, 200, 300, 400 ... Assist cover

Claims (7)

A housing that covers a portion of the rack shaft and accommodates a worm wheel that constitutes a speed reducing portion together with a worm that is rotationally driven by an electric motor;
A resin cover that is attached to the housing so as to cover the opening formed in the housing and has a through hole for ventilation,
A ventilation member attached to the through-hole formed in the cover and venting between the internal space and the external space of the housing;
Equipped with a,
The cover is tightened with respect to the housing by a tightening member, and has a recess recessed toward the housing from the outermost surface in the tightening direction of the tightening member. A steering device formed so that a periphery thereof is convex on the side opposite to the housing side . The steering device according to claim 1, wherein the cover has an outer peripheral wall provided along an outer periphery of the ventilation member. The steering device according to claim 2, wherein the outer peripheral wall has a notch formed in a vertically lower side. The concave portion of the cover is formed by a bottom surface provided closer to the housing than the annular outermost surface, and an inclined surface that is inclined with respect to the tightening direction from the outermost surface toward the bottom surface. ,
The steering apparatus according to any one of claims 1 to 3 , wherein the cover further includes a rib having an angle larger than an inclination angle of the inclined surface so as to connect the outermost surface and the bottom surface. The steering device according to claim 4 , wherein the through hole of the cover is formed at a central position on the bottom surface, and a plurality of the ribs are provided at equal intervals around the through hole. The housing is
A first housing covering a portion of the rack shaft;
A second housing having a support portion for supporting the electric motor and accommodating the worm wheel;
Have
The steering device according to any one of claims 1 to 5 , wherein the cover covers the opening formed in the second housing. It said vent member is a steering device according to any one clearance claim 1 having an O-ring for sealing the 6 between the arranged the cover between the cover.

Images