JP6900681B2 - Electric power steering device - Google Patents

Description

The present invention relates to an electric power steering device, and more particularly to an electric power steering device that applies an assist force to a steering device in an engine room.

There are various types of electric power steering devices such as column assist type and rack assist type. Electric power steering devices are classified based on what they transmit the driving force of the motor. For example, in the column assist type, the driving force of the motor is transmitted to the rack via the steering column. In the pinion assist type, the driving force of the motor is transmitted to the rack via the pinion shaft. In the intermediate shaft assist type, the driving force of the motor is transmitted to the rack via the pinion shaft and the intermediate shaft. In the rack assist type, the driving force of the motor is transmitted to the rack.

In the electric power steering device, the ECU (Electric Control Unit) and the motor are housed in a housing.

In the column-assisted electric power steering device, the motor is installed in the passenger compartment of a vehicle such as an automobile. Therefore, in the column assist type electric power steering device, the housing accommodating the motor and the ECU is not required to have waterproof performance.

On the other hand, in the rack assist type, the pinion assist type, and the intermediate shaft assist type, a motor is provided in the engine room. When the vehicle is running, water may enter the engine room. The water that has entered the engine room may enter the inside of the housing of the electric power steering device, so that the water that has entered the housing may come into contact with the ECU or the motor housed in the housing. It is not preferable to be exposed to water in order to operate the ECU and the motor. Therefore, in the type of electric power steering device in which a motor is provided in the engine room, the housing is required to be waterproof.

Japanese Unexamined Patent Publication No. 2015-54630 (Patent Document 1) discloses a rack-assisted electric power steering device. In this electric power steering device, the motor housing accommodating the motor is formed with a through hole for testing whether or not the motor housing maintains an airtight state. This through hole is opened in the lateral direction of the vehicle, and a sealing plug is inserted into the through hole. The sealing plug prevents water from entering the housing by closing the through hole.

Japanese Unexamined Patent Publication No. 2015-54630

In the electric power steering device of Japanese Patent Application Laid-Open No. 2015-54630 (Patent Document 1), as described above, since the through hole is opened in the lateral direction of the vehicle, the water that has entered the through hole is outside the through hole. Since it is not discharged, the sealing plug may come into contact with water for a long time. If the waterproofness of the sealing plug is deteriorated due to the deterioration of the sealing plug, the sealing plug may come into contact with water for a long period of time, so that water may enter the housing.

An object of the present invention is to provide a technique for improving waterproofness in an electric power steering device that applies an assist force to a steering device in an engine room.

The electric power steering device according to the present disclosure applies a rotational force to a shaft arranged in the engine room. The vertical direction of the electric power steering device is defined when the electric power steering device is mounted on the vehicle. The electric power steering device includes a motor, a speed reducer, a housing, a first sealing member, a second sealing member, and a sealing plug. The motor applies the rotational force of the shaft. The speed reducer applies the rotation of the motor to the shaft after reducing the rotation speed. The housing has an internal space through which the shaft penetrates in the vertical direction to accommodate the motor and speed reducer. The first sealing member seals the gap between the shaft and the opening for inserting the shaft provided at the upper end of the housing. The second sealing member seals the gap between the shaft and the opening for inserting the shaft provided at the lower end of the housing. The sealing plug allows gas to permeate and does not allow liquid to permeate. The lower end of the housing includes an upper surface and a lower surface. The upper surface faces the internal space of the housing. The lower surface faces the exterior space of the housing. The housing includes a hole that penetrates the top and bottom surfaces and opens downward on the bottom surface. The seal plug is blocking the hole.

According to the present disclosure, it is possible to improve the waterproofness of the electric power steering device that applies an assist force to the steering device in the engine room.

It is a schematic diagram which shows the whole structure of the electric power steering apparatus which concerns on embodiment of this invention. It is an external perspective view of the assist device shown in FIG. It is sectional drawing which cut | cut the assist device in the plane passing through the central axis of the intermediate shaft shown in FIG. FIG. 3 is an exploded cross-sectional view of the housing 30 shown in FIG. It is a side view of the sealing plug shown in FIG. In the cross-sectional view shown in FIG. 3, the area near the sealing plug is enlarged.

The electric power steering device according to the embodiment of the present invention applies a rotational force to a shaft arranged in the engine room. The vertical direction of the electric power steering device is defined when the electric power steering device is mounted on the vehicle. The electric power steering device includes a motor, a speed reducer, a housing, a first sealing member, a second sealing member, and a sealing plug. The motor applies the rotational force of the shaft. The speed reducer applies the rotation of the motor to the shaft after reducing the rotation speed. The housing has an internal space through which the shaft penetrates in the vertical direction to accommodate the motor and speed reducer. The first sealing member seals the gap between the shaft and the opening for inserting the shaft provided at the upper end of the housing. The second sealing member seals the gap between the shaft and the opening for inserting the shaft provided at the lower end of the housing. The sealing plug allows gas to permeate and does not allow liquid to permeate. The lower end of the housing includes an upper surface and a lower surface. The upper surface faces the internal space of the housing. The lower surface faces the exterior space of the housing. The housing includes a hole that penetrates the top and bottom surfaces and opens downward on the bottom surface. A sealing plug closes the hole (first configuration).

According to the first configuration, at the lower end of the housing, a hole is formed that penetrates the upper surface facing the inner space of the housing and the lower surface facing the outer space of the housing. This hole opens downward on the lower surface of the lower end of the housing and is closed by a sealing plug. When water enters this hole, the water that has entered the hole is quickly discharged from the lower opening. Therefore, it is possible to prevent the sealing plug from coming into contact with water for a long time, and it is possible to prevent liquids such as water from entering the inside of the housing through the holes. As a result, the waterproofness of the electric power steering device that imparts an assist force to the steering device in the engine room can be improved.

In the first configuration, the shaft is an intermediate shaft (second configuration). According to the second configuration, an assist force can be applied to the intermediate shaft.

In the first or second configuration, the electric power steering device further comprises a bracket. The bracket covers the opening of the hole on the underside at the lower end (third configuration).

According to the third configuration, since the bracket covers the lower opening in the hole, liquid such as water is prevented from directly entering the hole. As a result, the waterproofness of the electric power steering device can be improved.

According to any of the first to third configurations, the housing comprises a worm housing and an end housing. The worm housing houses the worms that make up the reducer. The end housing is located adjacent to the bottom of the worm housing and covers the lower end face of the worm housing. The worm housing includes an annular plate portion and a vent. The lower surface of the annular plate portion constitutes the lower end surface of the worm housing, and the upper surface faces the space for accommodating the worm. The ventilation holes penetrate the upper surface and the lower surface of the annular plate portion. The end housing includes a continuous hole. The continuous holes penetrate the upper and lower ends of the end housing. The holes are formed by the continuous arrangement of the ventilation holes and the continuous holes (fourth configuration).

According to the fourth configuration, after the housing assembly is completed, the housing air leak test can be performed using the holes. As a result, it is not necessary to form a test hole for the air leak test in the housing.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals, and the description thereof will not be repeated.

For convenience of explanation, each figure referred to in the following description shows the main members necessary for explaining the present invention among the embodiments of the present invention. Therefore, the present invention may include any component not shown in each of the following figures. In addition, the dimensions of the members in each of the following figures do not faithfully represent the actual dimensions and the dimensional ratio of each member.

[Configuration of Electric Power Steering Device 1]
FIG. 1 is a schematic view showing the overall configuration of the electric power steering device 1 according to the embodiment of the present invention. With reference to FIG. 1, the vehicle equipped with the electric power steering device 1 is divided into a vehicle compartment 2A and an engine compartment 2B by the dash panel 2. In FIG. 1, the space above the dash panel 2 is the vehicle interior 2A, and the space below the dash panel 2 is the engine room 2B.

In the following description, when the term "axial direction" is simply used, it means the extending direction of the intermediate shaft 13 shown in FIG. Further, in the present embodiment, "upward" is a direction in which the steering wheel 11 is viewed in the axial direction from the assist device 20. The “downward” in the present embodiment is the direction in which the rack 16 is viewed from the assist device 20 in the axial direction.

Further, the "lateral direction" is the direction in which the rack 16 extends, and corresponds to the left-right direction of the vehicle on which the electric power steering device 1 is mounted. One of the lateral directions is the direction on the right side of the paper in FIG. 1, and corresponds to the right direction when the front is viewed from the driver's seat of the vehicle equipped with the electric power steering device 1. The other lateral direction is the direction on the left side of the paper in FIG. 1, and corresponds to the left direction when the front is viewed from the driver's seat of the vehicle equipped with the electric power steering device 1.

The electric power steering device 1 includes a steering wheel 11, a steering shaft 12, an intermediate shaft 13, a pinion shaft 14, a pinion 15, a rack 16, tie rods 17, 17 and an assist device 20.

The upper end of the steering shaft 12 is connected to the steering wheel 11, and the lower end of the steering shaft 12 is connected to the upper end of the intermediate shaft 13 by a universal joint 25a.

The lower end of the intermediate shaft 13 is connected to the upper end of the pinion shaft 14 by a universal joint 25b.

A pinion 15 is connected to the lower end of the pinion shaft 14. The pinion 15 rotates in conjunction with the operation of the steering wheel 11 by the driver of the vehicle. The rack 16 extends laterally to the vehicle and meshes with the pinion 15.

The rotational motion of the pinion shaft 14 is converted into a linear motion of the rack 16 by the pinion 15 and the rack 16. That is, the rack 16 moves in the lateral direction of the vehicle by the rotation of the pinion shaft 14. The tie rod 17 pushes and pulls the rolling wheel 3 of the vehicle in response to the lateral movement of the rack 16, so that the vehicle is steered.

The assist device 20 is arranged in the engine room 2B, and applies an assist force to assist the rotation of the steering wheel 11 performed by the driver of the vehicle to the intermediate shaft 13. The assist device 20 includes a torque sensor 21, an ECU (Electronic Control Unit) 22, a motor 23, and a speed reducer 24.

The torque sensor 21 detects the torque generated in the intermediate shaft 13. The ECU 22 supplies the motor 23 with a current corresponding to the torque detected by the torque sensor 21 and the vehicle speed detected by the vehicle speed sensor (not shown). The motor 23 is driven based on the current supplied from the ECU 22 to generate torque. The speed reducer 24 amplifies the torque generated by the motor 23 and applies it to the intermediate shaft 13. Specifically, the speed reducer 24 is a worm moderator including a worm 24a and a worm wheel 24b.

The worm 24a rotates together with the rotation shaft of the motor 23. The worm wheel 24b rotates according to the rotation of the worm 24a. Since the worm wheel 24b is fixed to the intermediate shaft 13, the intermediate shaft 13 rotates together with the worm wheel 24b. As a result, the assist force is applied to the intermediate shaft 13.

[Configuration of Assist Device 20]
(Structure of housing 30)
FIG. 2 is an external perspective view of the assist device 20 shown in FIG. The central axis L1 shown in FIG. 2 is the central axis of the intermediate shaft 13. The central axis L2 is in a twisted position with the central axis L1 and extends in the lateral direction (the extending direction of the rack 16 shown in FIG. 1).

As shown in FIG. 2, the assist device 20 further includes a housing 30 and a sealing stopper 45.

The intermediate shaft 13 penetrates the housing 30 in the axial direction. The housing 30 houses the torque sensor 21, the ECU 22, the motor 23, and the speed reducer 24.

As shown in FIG. 1, the assist device 20 is arranged in the engine room 2B. Since water may enter the engine room 2B from below the vehicle, the housing 30 shown in FIG. 2 may be exposed to water. When a liquid such as water enters the inside of the housing 30, the water that has entered the housing 30 may come into contact with the ECU 22 and the motor 23 housed in the housing 30. The housing 30 has a waterproof function in order to suppress the influence of water that has entered the engine room 2B.

The housing 30 includes a motor housing 31, a worm housing 32, and an end housing 33.

FIG. 3 is a sectional view taken along line III-III of the assist device 20 shown in FIG. That is, FIG. 3 is a cross-sectional view of the assist device 20 shown in FIG. 2 cut along a plane passing through the central axis L1 of the intermediate shaft 13. With reference to FIG. 3, the housing 30 further comprises a sensor housing 34.

As shown in FIG. 3, the end housing 33, the sensor housing 34, and the worm wheel accommodating portion 322 in the worm housing 32 are arranged coaxially. That is, the central axes of the end housing 33, the sensor housing 34, and the worm wheel accommodating portion 322 coincide with the central axis L1 of the intermediate shaft 13. The end housing 33 is arranged adjacent to the lower side of the worm housing 32 in the axial direction. The sensor housing 34 is arranged adjacent to the upper side of the worm housing 32 in the axial direction. As shown in FIG. 2, the motor housing 31 is arranged adjacent to one of the worm housings 32 in the lateral direction.

As shown in FIG. 3, the sealing plug 45 is inserted into a hole 40 that axially penetrates the worm housing 32 and the end housing 33, and closes the hole 40. The hole 40 is a hole different from the hole into which the intermediate shaft 13 is inserted. Since the sealing plug 45 has a function of allowing a gas such as air to permeate and not allowing a liquid such as water to permeate, the liquid such as water penetrates into the inside of the housing 30 from the outside of the housing 30 through the hole 40. Prevent from doing. Details of the sealing stopper 45 and the hole 40 will be described later.

(Intermediate shaft 13)
The configuration of the intermediate shaft 13 will be described. As shown in FIG. 3, the intermediate shaft 13 includes an input shaft 131, an output shaft 132, and a torsion bar 133.

The input shaft 131 is a portion of the intermediate shaft 13 above the axial direction. The upper end of the input shaft 131 is connected to the steering shaft 12 by the universal joint 25a shown in FIG. The output shaft 132 is a portion of the intermediate shaft 13 below the axial direction. The lower end of the output shaft 132 is connected to the pinion shaft 14 by the universal joint 25b shown in FIG. The torsion bar 133 connects the lower end of the input shaft 131 and the upper end of the output shaft 132.

When the driver of the vehicle operates the steering wheel 11 shown in FIG. 1, the input shaft 131 of the intermediate shaft 13 shown in FIG. 3 rotates together with the steering shaft 12. The rotation of the input shaft 131 of the intermediate shaft 13 causes elastic torsional deformation in the torsion bar 133. As a result, in the intermediate shaft 13, a relative displacement in the rotation direction around the central axis L1 occurs between the input shaft 131 and the output shaft 132. The torque sensor 21 detects the torque generated in the intermediate shaft 13 based on the relative displacement generated between the input shaft 131 and the output shaft 132.

(Motor housing 31)
As shown in FIG. 2, the motor housing 31 has a tubular shape extending in the lateral direction. That is, the motor housing 31 extends in the extending direction of the central axis L1 and the central axis L2 at the twisted position. In the example shown in FIG. 2, the central axis of the motor housing 31 coincides with the central axis L2. The motor housing 31 accommodates the ECU 22 and the motor 23, which are not shown in FIG.

The motor housing 31 is arranged adjacent to one side surface of the worm housing 32 in the lateral direction. In the motor housing 31, the other end in the lateral direction is open and the other end in the lateral direction is closed. The other lateral end of the motor housing 31 is connected by bolts and nuts to the flange 323 formed on the worm housing 32.

(Warm housing 32)
As shown in FIG. 2, the worm housing 32 includes a worm accommodating portion 321, a worm wheel accommodating portion 322, and a flange 323. The worm accommodating portion 321, the worm wheel accommodating portion 322, and the flange 323 are integrally formed.

The worm accommodating portion 321 has a tubular shape extending in the lateral direction. That is, the worm accommodating portion 321 extends in the extending direction of the central axis L2. In the example shown in FIG. 2, the central axis of the worm accommodating portion 321 coincides with the central axis L2. The worm accommodating section 321 accommodates the worm 24a (not shown in FIG. 2). Although not shown in FIG. 2, the worm 24a is arranged in the worm accommodating portion 321 so as to extend in the extending direction of the central axis L2, and is connected to the rotation axis of the motor 23 accommodated in the motor housing 31. Has been done.

As shown in FIG. 3, the worm wheel accommodating portion 322 has a tubular shape extending in the axial direction. That is, the worm wheel accommodating portion 322 extends in the direction of the central axis L1. The central axis of the worm wheel accommodating portion 322 coincides with the central axis L1. The worm wheel accommodating portion 322 accommodates the worm wheel 24b. Further, the intermediate shaft 13 penetrates the worm wheel accommodating portion 322 in the axial direction. The worm wheel 24b is fixed to the output shaft 132 of the intermediate shaft 13 so as to rotate about the central axis L1.

As shown in FIG. 2, the flange 323 has an annular shape when viewed from the extending direction of the central axis L2, and is arranged on one side surface of the worm housing 32 in the lateral direction. As described above, the flange 323 is connected to the opening of the motor housing 31.

Hereinafter, the configuration of the worm wheel accommodating portion 322 will be described in detail. FIG. 4 is an exploded cross-sectional view of the housing 30 shown in FIG. In FIG. 4, the display of the components of the assist device 20 other than the worm housing 32, the end housing 33, and the sensor housing 34 is omitted.

As shown in FIG. 4, the worm wheel accommodating portion 322 has an annular plate portion 51, a tubular portion 52, and an annular protrusion 53.

As shown in FIG. 4, the annular plate portion 51 has a plate-like shape that extends continuously in the circumferential direction about the central axis L1. That is, the annular plate portion 51 has an annular shape when viewed from the axial direction. The annular plate portion 51 includes an annular surfaces 51a and 51b and a through hole 51c.

The annular surface 51a is the surface of the annular plate portion 51 on the lower side in the axial direction, and the annular surface 51b is the surface of the annular plate portion 51 on the upper side in the axial direction. An annular groove 51d is formed on the annular surface 51a. The details of the annular groove 51d will be described later.

The through hole 51c penetrates the annular plate portion 51 in the axial direction. The intermediate shaft 13 is inserted into the through hole 51c. As shown in FIG. 3, the bearing 36 is press-fitted into the through hole 51c of the annular plate portion 51. The bearing 36 holds the output shaft 132 so that the output shaft 132 of the intermediate shaft 13 can rotate about the central axis L1.

As shown in FIG. 4, the annular plate portion 51 further includes a ventilation hole 55. The ventilation hole 55 is a hole that penetrates the annular surface 51a and the annular surface 51b of the annular plate portion 51, and extends in the axial direction. That is, the ventilation hole 55 is opened on the lower surface of the worm housing 32. The ventilation hole 55 extends parallel to the through hole 51c, that is, extends in the extending direction of the central axis L1, and is located outside the radial direction of the through hole 51c. Here, the radial direction means the radial direction centered on the central axis L1, and the radial direction coincides with the lateral direction in FIGS. 3 and 4. The ventilation hole 55 constitutes a part of the hole 40 shown in FIG. 2, and includes a large diameter portion 55a and an enlarged diameter portion 55b.

The large diameter portion 55a is arranged axially lower than the enlarged diameter portion 55b. The lower end in the axial direction of the large diameter portion 55a is continuous with the annular surface 51a of the annular plate portion 51, and the upper end in the axial direction of the large diameter portion 55a is continuous with the lower end in the axial direction of the enlarged diameter portion 55b. doing. The inner diameter of the large diameter portion 55a is constant in the axial direction.

The enlarged diameter portion 55b is arranged axially above the large diameter portion 55a. The axially upper end of the enlarged diameter portion 55b is continuous with the annular surface 51b of the annular plate portion 51. The diameter-expanded portion 55b has a tapered shape in which the inner diameter of the diameter-expanded portion 55b increases from the upper side in the axial direction to the lower side in the axial direction.

As shown in FIG. 4, the tubular portion 52 has a tubular shape extending in the extending direction of the central axis L1, and extends upward in the axial direction from the outer peripheral end portion of the annular plate portion 51. A worm wheel 24b fixed coaxially with the intermediate shaft 13 is housed in the space surrounded by the inner peripheral surface 52a of the tubular portion 52.

Further, the tubular portion 52 further includes connection holes 52b and 52b. The connection hole 52b is a hole that penetrates the tubular portion 52 in the axial direction, and is located radially outward of the inner peripheral surface 52a of the tubular portion 52. That is, the central axis of the connection hole 52b is a straight line different from the central axis L1 and coincides with a straight line parallel to the central axis L1. The connection holes 52b and 52b are not annular holes centered on the central axis L1 (not holes extending in the circumferential direction), but two holes formed at positions outward in the radial direction from the inner peripheral surface 52a. is there. In addition, three or more connection holes 52b may be formed. In this case, the connection holes 52b, 52b ... Are a plurality of holes formed at a plurality of locations in the circumferential direction at positions outward in the radial direction from the inner peripheral surface 52a.

As shown in FIG. 4, the annular protrusion 53 projects downward in the axial direction from the annular surface 51a of the annular plate portion 51, and has an annular shape when viewed from the axial direction. The annular protrusion 53 includes a through hole 53a. The through hole 53a penetrates the annular protrusion 53 in the axial direction and is continuous with the through hole 51c formed in the annular plate portion 51. The central axis of the through hole 53a coincides with the central axis L1.

As shown in FIG. 4, the annular groove 51d is formed on the annular surface 51a, which is the axially lower end surface of the annular plate portion 51, as described above. The annular groove 51d is a groove that opens downward in the axial direction. The annular groove 51d is an annular groove centered on the central axis L1 when viewed from the axial direction. The annular groove 51d is closer to the central axis L1 than the ventilation hole 55, and is farther from the central axis L1 than the connection portion between the annular surface 51a and the outer peripheral surface of the annular protrusion 53. The O-ring 56 shown in FIG. 3 is fitted into the annular groove 51d. In the O-ring 56, when the annular protrusion 53 of the worm wheel accommodating portion 322 is fitted into the through hole 70 of the end housing 33, a gas such as air or a liquid such as water is between the worm housing 32 and the end housing 33. It is prevented from entering the inside of the housing 30 through the housing 30.

(Sensor housing 34)
As shown in FIG. 4, the sensor housing 34 has a tubular shape extending in the axial direction and includes a through hole 60. The through hole 60 penetrates the sensor housing 34 in the axial direction. The central axis of the through hole 60 coincides with the central axis L1. The sensor housing 34 includes a small diameter portion 61, a medium diameter portion 62, a large diameter portion 63, and a flange 64.

The small diameter portion 61 is an axially upward end portion of the sensor housing 34, and is located axially upward with respect to the medium diameter portion 62 and the large diameter portion 63. The medium diameter portion 62 is located between the small diameter portion 61 and the large diameter portion 63 in the axial direction. The outer diameter of the middle diameter portion 62 is larger than the outer diameter of the small diameter portion 61 and smaller than the outer diameter of the large diameter portion 63. The large diameter portion 63 is an axially lower end portion of the sensor housing 34, and is located axially lower than the small diameter portion 61 and the medium diameter portion 62. The outer diameter of the large diameter portion 63 is larger than the outer diameter of each of the small diameter portion 61 and the medium diameter portion 62.

As shown in FIG. 3, the intermediate shaft 13 is inserted into the through hole 60 of the sensor housing 34. The bearing 37 is press-fitted into the inner peripheral surface of the large diameter portion 63. The bearing 37 rotatably holds the output shaft 132 of the intermediate shaft 13. The bearing 38 is press-fitted into the inner peripheral surface of the small diameter portion 61. The bearing 38 rotatably holds the input shaft 131 of the intermediate shaft 13.

As shown in FIG. 3, the oil seal 39A seals a gap between the small diameter portion 61 of the sensor housing 34 and the input shaft 131 of the intermediate shaft 13. The oil seal 39A corresponds to the first sealing member in the present invention. The small diameter portion 61 of the sensor housing 34 corresponds to the opening for inserting the intermediate shaft 13 provided at the upper end of the housing 30 in the present invention. The oil seal 39A prevents a gas such as air or a liquid such as water from entering the internal space of the housing 30 through the gap between the sensor housing 34 and the input shaft 131 of the intermediate shaft 13.

As shown in FIG. 3, the sensor housing 34 accommodates the torque sensor 21 in the space between the bearing 37 and the bearing 38 in the through hole 60. The torque sensor 21 is, for example, a resolver, and is arranged so as to surround the intermediate shaft 13 inserted in the through hole 60 in the circumferential direction around the central axis L1.

As shown in FIG. 4, the flange 64 extends in the radial direction from the outer peripheral side surface of the medium diameter portion 62. The flange 64 is annular when viewed from the axial direction. The flange 64 includes connection holes 64a, 64a. The connection holes 64a and 64a are holes that penetrate the flange 64 in the axial direction, and are located radially outward of the through holes 60. The connection holes 64a and 64a are not annular holes centered on the central axis L1 (not holes extending in the circumferential direction), but two holes formed at positions outward in the radial direction from the through hole 60, respectively. .. In addition, three or more connection holes 64a may be formed. In this case, the connection holes 64a, 64a ... Are a plurality of holes formed at a plurality of locations in the circumferential direction at positions outward in the radial direction from the through hole 60.

The connection hole 64a is provided so as to be aligned with the connection hole 52b formed in the worm wheel accommodating portion 322. The inner diameter of the connection hole 64a is the same as the inner diameter of the connection hole 52b formed in the worm wheel accommodating portion 322.

An annular groove 65 is formed on the outer peripheral surface of the large diameter portion 63. The annular groove 65 is continuous in the circumferential direction with the central axis L1 as the center, and is open in the lateral direction. That is, the annular groove 65 opens outward in the radial direction. As shown in FIG. 3, an O-ring 66 is fitted in the annular groove 65. In the O-ring 66, when the large diameter portion 63 of the sensor housing 34 is fitted into the inner peripheral surface 52a of the tubular portion 52 of the worm wheel accommodating portion 322, a gas such as air or a liquid such as water is introduced into the worm wheel accommodating portion. It is prevented from entering the inside of the housing 30 through the space between the 322 and the sensor housing 34.

(End housing 33)
As shown in FIG. 3, the end housing 33 has a tubular shape extending in the axial direction, and covers the annular surface 51a which is the lower surface of the annular plate portion 51 in the worm wheel accommodating portion 322 of the worm housing 32.

The end housing 33 includes a through hole 70. The through hole 70 penetrates the end housing 33 in the axial direction. The central axis of the through hole 70 coincides with the central axis L1. The output shaft 132 of the intermediate shaft 13 is inserted into the through hole 70.

As shown in FIG. 4, the end housing 33 includes an annular plate portion 71 and an annular protrusion 72.

The annular plate portion 71 has a plate-like shape that extends continuously in the circumferential direction about the central axis L1. That is, the annular plate portion 71 has an annular shape when viewed from the axial direction. The annular plate portion 71 includes the annular surfaces 71a and 71b. The annular surface 71a is the surface of the annular plate portion 71 on the lower side in the axial direction, and the annular surface 71b is the surface of the annular plate portion 71 on the upper side in the axial direction.

The annular plate portion 71 further includes a continuous hole 71c. The continuous hole 71c is a hole that penetrates the annular surface 71a and the annular surface 71b of the annular plate portion 71, and extends in the axial direction. That is, the continuous hole 71c is opened in the upper axial direction and the lower axial direction of the end housing 33. The continuous hole 71c is parallel to the through hole 70 and is located outward in the radial direction of the through hole 70. Further, the inner diameter of the continuous hole 71c is the same as the inner diameter of the ventilation hole 55.

The continuous hole 71c is formed at a position continuous with the ventilation hole 55 of the worm wheel accommodating portion 322 when the housing 30 is assembled. The continuous hole 71c constitutes the hole 40 together with the ventilation hole 55. That is, when the annular protrusion 53 of the worm wheel accommodating portion 322 is fitted into the through hole 70 of the end housing 33, the ventilation hole 55 of the worm wheel accommodating portion 322 and the continuous hole 71c of the end housing 33 are continuously provided. One hole 40 is formed.

Further, as shown in FIG. 4, the annular plate portion 71 includes connection holes 71d and 71d. The connection hole 71d is a hole that penetrates the annular plate portion 71 in the axial direction, and the connection hole 71d is located on the outer peripheral side of the annular plate portion 71 with respect to the continuous hole 71c. The connection holes 71d and 71d are not annular holes centered on the central axis L1 (not holes extending in the circumferential direction), but two holes formed at positions outward in the radial direction from the through hole 0, respectively. .. In addition, three or more connection holes 71d may be formed. In this case, the connection holes 71d, 71d ... Are a plurality of holes formed at a plurality of locations in the circumferential direction at positions outward in the radial direction from the through holes 70. The inner diameter of the connection hole 71d is the same as the inner diameter of the connection hole 52b formed in the worm wheel accommodating portion 322.

As shown in FIG. 4, the annular protrusion 72 protrudes downward in the axial direction from the annular surface 71a, which is the lower surface of the annular plate portion 71, and has an annular shape when viewed from the axial direction. The annular protrusion 72 is arranged at a position that does not block the opening below the continuous hole 71c of the annular plate 71. The annular protrusion 72 corresponds to the lower end of the housing 30.

As shown in FIG. 4, the annular protrusion 72 has annular surfaces 72a and 72b. The annular surfaces 72a and 72b are axially lower end surfaces of the annular protrusion 72 and are perpendicular to the central axis L1. The annular surface 72a is located axially below the annular surface 72b. The annular surface 72b is located axially lower than the annular surface 71a, which is the surface of the annular plate portion 71 on the lower side in the axial direction. The inner diameter of the annular surface 72a of the annular plate portion 71 is smaller than the inner diameter of the annular surface 72b. That is, a step is formed by the annular surfaces 72a and 72b on the axially lower end surface of the annular protrusion 72.

As shown in FIG. 3, the oil seal 39B seals the gap formed between the annular protrusion 72 of the end housing 33 and the output shaft 132 of the intermediate shaft 13 inserted into the through hole 70. There is. The oil seal 39B corresponds to the second sealing member in the present invention. The annular protrusion 72 of the end housing 33 corresponds to the opening for inserting the intermediate shaft 13 provided at the lower end of the housing 30 in the present invention. In the oil seal 39B, when the annular protrusion 53 of the worm wheel accommodating portion 322 is fitted into the through hole 70 of the end housing 33, gas such as air or liquid such as water is output from the end housing 33 and the intermediate shaft 13. It is prevented from entering the inside of the housing 30 through the gap between the shaft 132 and the shaft 132.

As shown in FIG. 2, the end housing 33 further includes three mounting portions 73, 73, 73. Each of the mounting portions 73, 73, and 73 protrudes in the radial direction from the outer peripheral surface of the annular plate portion 71. The mounting portions 73, 73, 73 are used to fix the assist device 20 to the frame of a vehicle (not shown).

(Bracket 35)
As shown in FIG. 3, the bracket 35 is arranged axially below the housing 30. Specifically, the bracket 35 is arranged axially lower than the end housing 33 and covers the lower end portion of the housing 30 in the axial direction. That is, the bracket 35 covers the opening of the continuous hole 71c formed in the annular plate portion 71 of the end housing 33. The bracket 35 is formed, for example, by pressing a metal plate.

The bracket 35 includes a lower stage portion 351, a middle stage portion 352, and an upper stage portion 353. The middle portion 352 and the upper portion 353 are located on the other side in the lateral direction from the central axis L1. The lower portion 351 is located axially lower than the middle portion 352 and the upper portion 353. The middle section 352 is located between the lower section 351 and the upper section 353 in the axial direction. The upper portion 353 is located axially above the lower portion 351 and the middle portion 352. That is, a step is provided in the axial direction between the lower step portion 351 and the middle step portion 352, and a step is provided in the axial direction between the middle step portion 352 and the upper step portion 353.

With reference to FIGS. 3 and 4, the upper surface of the lower portion 351 is in contact with the annular surface 72a of the annular protrusion 72 in the state where the bracket 35 is assembled. The lower portion 351 includes a through hole 35a. The through hole 35a penetrates the lower portion 351 of the bracket 35 in the axial direction. The central axis of the through hole 35a coincides with the central axis L1, and the output shaft 132 of the intermediate shaft 13 is inserted into the through hole 35a.

The upper surface of the middle stage portion 352 has a region in contact with the annular surface 72b of the annular projection portion 72 and a region covering a part of the opening in the lower axial direction of the continuous hole 71c. The upper surface of the upper portion 353 has a region that contacts the lower surface of the tubular portion 52 and a region that covers a part of the opening in the lower axial direction of the continuous hole 71c. That is, the opening of the continuous hole 71c in the lower direction in the axial direction is covered by the middle stage portion 352 and the upper stage portion 353. In other words, in the bracket 35, the middle step portion 352 and the upper step portion 353 cover the axially lower opening in the hole 40.

(Seal stopper 45)
FIG. 5 is a side view of the sealing stopper 45 shown in FIG. As shown in FIG. 5, the sealing plug 45 includes a disk portion 46, legs 47, 47, and an O-ring 48. Polybutylene terephthalate (PBT-GF30, etc.) is used, for example, for the portion of the sealing stopper 45 excluding the disk portion 46 (leg portions 47, 47, etc.).

The disk portion 46 has a circular shape when viewed from the axial direction. The disk portion 46 is formed of, for example, a resin that allows a gas such as air to permeate and does not allow a liquid such as water to permeate. The resin used for the disk portion 46 is, for example, a PTFE (polytetrafluoroethylene) porous membrane. The resin forming the disk portion 46 preferably has elasticity. The diameter of the disk portion 46 is the same as the inner diameter of the large diameter portion 55a of the ventilation hole 55, or larger than the inner diameter of the large diameter portion 55a of the ventilation hole 55.

Each of the legs 47 and 47 has a hook-like shape extending axially upward from the upper surface of the disk portion 46. That is, each of the legs 47 and 47 extends upward in the axial direction from the upper surface of the disk portion 46, and then bends from the center of the disk portion 46 toward the outer peripheral direction of the disk portion 46. In other words, the tips 47a, 47a of the legs 47, 47 are located between the connecting portion between the legs 47, 47 and the disk portion 46 and the outer peripheral surface of the disk portion 46. The O-ring 48 is arranged in contact with the upper surface of the disk portion 46 so as to surround both the legs 47 and 47.

(Fixing of worm housing 32, etc.)
Hereinafter, fixing of the motor housing 31, the worm housing 32, the end housing 33, and the sensor housing 34 constituting the housing 30 will be described. The description of the torque sensor 21 and the like housed in the housing 30 will be omitted.

With reference to FIG. 3, first, the O-ring 56 is fitted into the annular groove 51d formed in the worm wheel accommodating portion 322 of the worm housing 32, and the O-ring 66 is fitted into the annular groove 65 formed in the sensor housing 34. Include. The bearing 36 is press-fitted into the inner peripheral surface of the annular plate portion 51 of the worm housing 32. The bearing 37 is press-fitted into the inner peripheral surface of the large diameter portion 63 of the sensor housing 34. The bearing 38 is press-fitted into the inner peripheral surface of the small diameter portion 61 of the sensor housing 34.

The sensor housing 34, the worm housing 32, and the end housing 33 are arranged in this order from the upper side to the lower side in the axial direction. The sensor housing 34, the worm housing 32, and the end housing 33 arranged as described above are aligned. Specifically, referring to FIG. 4, the connection holes 64a and 64a of the sensor housing 34, the connection holes 52b and 52b of the worm housing 32, and the connection holes 71d and 71d of the end housing 33 are continuous in the axial direction. The alignment is performed so that the vent hole 55 and the continuous hole 71c form one hole 40 which is continuous in the axial direction.

After that, the sensor housing 34 is moved to the worm wheel of the worm housing 32 so that the outer peripheral surface of the large diameter portion 63 of the sensor housing 34 comes into contact with the inner peripheral surface 52a of the tubular portion 52 in the worm wheel accommodating portion 322 of the worm housing 32. It is fitted into the accommodating portion 322. The annular protrusion 53 of the worm wheel accommodating portion 322 of the worm housing 32 is fitted into the through hole 70 of the end housing 33. The end housing 33 and the sensor housing are formed by inserting bolts into the holes in which the connection holes 64a and 64a of the sensor housing 34, the connection holes 52b and 52b of the worm housing 32, and the connection holes 71d and 71d of the end housing 33 are continuous. 34 is fixed to the worm housing 32.

With reference to FIG. 2, the opening of the motor housing 31 and the flange 323 of the worm housing 32 are butted against each other, and then the motor housing 31 is fixed to the worm housing 32 using bolts and nuts.

With reference to FIG. 3, the intermediate shaft 13 is inserted into the connected sensor housing 34, worm housing 32 and end housing 33. Specifically, the input shaft 131 of the intermediate shaft 13 is inserted into the through hole 60 of the sensor housing 34 and is rotatably held by the bearing 38. The output shaft 132 of the intermediate shaft 13 is inserted into the through holes 51c and 53a of the worm wheel accommodating portion 322 and the through holes 70 of the end housing 33, and is rotatably held by the bearings 36 and 37. The oil seal 39A is press-fitted into the through hole 60 of the sensor housing 34, and the oil seal 39B is press-fitted into the through hole 70 of the end housing 33.

FIG. 6 is an enlarged view of the vicinity of the sealing plug 45 in the assist device 20 shown in FIG. As shown in FIG. 6, the sealing plug 45 is inserted into the hole 40. Specifically, the sealing plug 45 is inserted into the hole 40 of the end housing 33 with the legs 47, 47 of the sealing plug 45 facing upward in the axial direction from the disk portion 46. Then, the sealing plugs 45 are positioned so that the tips 47a, 47a of the legs 47, 47 are located axially above the annular surface 51b, which is the upper surface of the annular plate portion 51 of the worm wheel accommodating portion 322. Push in 45. As a result, the disk portion 46 of the sealing plug 45 is located in the ventilation hole 55. This completes the assembly of the housing 30.

(Action and effect of housing 30)
In the housing 30 assembled as described above, the O-ring 66 seals between the worm housing 32 and the sensor housing 34, and the O-ring 56 seals between the worm housing 32 and the end housing 33. .. Further, the oil seal 39A seals the gap between the sensor housing 34 and the input shaft 131 of the intermediate shaft 13, and the oil seal 39B seals the gap between the end housing 33 and the output shaft 132 of the intermediate shaft 13. To do. As a result, the hole 40 is the only path through which a gas such as air or a liquid such as water can enter the internal space of the housing 30 from the outside of the housing 30.

Then, by closing the hole 40 with the sealing plug 45, it is possible to prevent a liquid such as water from entering the internal space of the housing 30.

As shown in FIG. 6, the end housing 33 and the annular plate portion 51 of the worm wheel accommodating portion 322 form an axially lower end portion of the housing 30. Specifically, the annular plate portion 51 of the worm wheel accommodating portion 322 and the annular plate portion 71 of the end housing 33 form an axially lower end portion of the housing 30. A hole 40 is formed at the lower end of the housing 30 in the axial direction.

The hole 40 penetrates the upper surface (annular surface 51b) of the annular plate portion 51 of the worm wheel accommodating portion 322 and the lower surface (annular surface 71a) of the annular plate portion 71 of the end housing 33. By inserting the sealing plug 45 into the hole 40, the sealing plug 45 closes the ventilation hole 55. The disk portion 46 of the sealing plug 45 allows a liquid such as air to permeate, but does not allow a liquid such as water to permeate. Therefore, it is possible to prevent liquids such as water from entering the internal space of the housing 30 from the outside of the housing 30 through the ventilation holes 55. Further, the O-ring 48 is in contact with the enlarged diameter portion 55b of the ventilation hole 55. Therefore, even if a liquid such as water passes through the gap between the disk portion 46 of the sealing plug 45 and the large diameter portion 55a of the ventilation hole 55 and reaches the upper surface of the disk portion 46, the O-ring 48 can be used. It is possible to prevent water such as a liquid from entering the internal space of the housing 30.

Further, since the disk portion 46 of the sealing plug 45 can allow a gas such as air to pass through, the air pressure in the internal space of the housing 30 can be adjusted. As described above, the housing 30 is arranged in the engine room 2B. The temperature of the internal space of the housing 30 may rise due to heat generated by the engine arranged in the engine room 2B, and the air pressure of the internal space of the housing 30 may rise. In this case, the air in the internal space of the housing 30 can move to the outside of the housing 30 through the sealing plug 45 inserted in the ventilation hole 55. At this time, the tips 47a, 47a of the legs 47, 47 of the sealing plug 45 are positioned axially above the annular surface 51b, which is the upper surface of the annular plate portion 51 of the worm wheel accommodating portion 322. The sealing plug 45 is prevented from falling out of the hole 40 when the air in the internal space moves to the outside of the housing 30. When the engine is stopped, the internal temperature of the housing 30 may be lowered, and the internal air pressure of the housing 30 may be lowered. In this case, the air outside the housing 30 is taken into the inside of the housing 30 through the sealing plug 45 inserted into the ventilation hole 55. In this way, by closing the ventilation hole 55 with the sealing plug 45, it is possible to adjust the air pressure in the internal space of the housing 30.

Further, referring to FIG. 6, the hole 40 formed by the ventilation hole 55 and the continuous hole 71c opens downward in the axial direction on the surface of the housing 30 in the lower direction in the axial direction. Water that has entered the engine room 2B from below the vehicle may enter the hole 40. Since the hole 40 is opened downward in the axial direction, the water that has entered the hole 40 is quickly discharged to the outside of the hole 40. That is, it is prevented that water stays in the hole 40 for a long time. Since the time for the sealing plug 45 inserted in the hole 40 to come into contact with water can be shortened, it is possible to prevent the water that has entered the hole 40 from entering the internal space of the housing 30 through the ventilation hole 55. can do.

In the bracket 35, the middle step portion 352 and the upper step portion 353 cover the axially lower opening in the hole 40. Therefore, the water that has entered the engine room 2B is suppressed from directly entering the hole 40 from below in the axial direction. As a result, the waterproof function of the housing 30 can be further improved.

By bringing a part of the upper surface of the upper portion 353 into contact with the lower surface of the tubular portion 52, the upper surface of the bracket 35 can be brought closer to the opening in the lower axial direction of the hole 40. Since it is possible to further prevent water that has entered the engine room 2B from directly entering the hole 40 from below in the axial direction, the waterproof function of the housing 30 can be further improved. A part of the upper surface of the upper portion 353 is in contact with the lower surface of the tubular portion 52, but the upper surface of the upper portion 353 and the lower surface of the tubular portion 52 are not sealed. Since gas such as air can reach the hole 40 from the outside of the housing 30 through the gap between the upper surface of the upper portion 353 and the lower surface of the tubular portion 52, the air pressure in the internal space of the housing 30 is adjusted. It is possible to do.

Further, before inserting the sealing plug 45 into the hole 40, it is possible to perform an air leak test using the hole 40. The air leak test is performed to determine whether or not the housing 30 has a waterproof function. Specifically, the air leak test is performed by filling the inside of the housing 30 with air through the holes 40 and then measuring the change in air pressure inside the housing 30. Since the air leak test can be performed using the holes 40 after the assembly of the housing 30 is completed, it is not necessary to form a test hole for the air leak test in the housing.

[Modification example]
In the above embodiment, an example in which the sealing plug 45 has the shape shown in FIG. 5 has been described, but the present invention is not limited to this. The sealing plug 45 has a function of allowing gas to permeate and not allowing liquid to permeate, and its shape is not particularly limited as long as the hole 40 can be closed.

Further, in the above embodiment, an example in which the assist device 20 includes the bracket 35 has been described, but the present invention is not limited to this. The assist device 20 does not have to include the bracket 35. Even in this case, since the hole 40 is opened downward in the axial direction, the water that has entered the hole 40 can be quickly discharged.

Further, in the above embodiment, an example in which the housing 30 includes the end housing 33 has been described, but the present invention is not limited to this. The housing 30 does not have to include the end housing 33. In this case, since the lower end of the housing 30 in the axial direction becomes the annular plate portion 51 of the worm wheel accommodating portion 322, the hole 40 is formed only by the ventilation hole 55. The oil seal 39B may seal the gap formed between the annular plate portion 51 and the output shaft 132 of the intermediate shaft 13.

That is, the hole 40 is a hole formed at the lower end of the housing 30 in the axial direction, and penetrates the upper surface of the housing 30 facing the internal space and the lower surface of the housing 30 facing the external space. It suffices if the housing 30 is open downward on the lower surface of the axially lower end portion of the housing 30.

Further, in the above embodiment, an example in which the bracket 35 includes the lower portion 351 and the middle portion 352 and the upper portion 353 has been described, but the present invention is not limited to this. The bracket 35 may be a plate-shaped member having no step. Even in this case, since the bracket 35 can cover the opening below the axial direction of the hole 40, the waterproof function of the housing 30 can be further improved. That is, the bracket 35 may cover the opening of the hole 40 at the lower end of the housing 30.

Further, in the above embodiment, an example in which the assist device 20 applies the assist force to the intermediate shaft 13 has been described, but the present invention is not limited to this. The assist device 20 may apply an assist force to the pinion shaft 14. Further, when a part of the steering shaft 12 is arranged in the engine room 2B, the assist device 20 may apply an assist force to the steering shaft 12. That is, the assist device 20 may be arranged in the engine room 2B and may apply an assist force to the shaft that rotates according to the rotation of the steering wheel 11.

Although the embodiments of the present invention have been described above, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and the above-described embodiment can be appropriately modified and implemented within a range that does not deviate from the gist thereof.

1 Electric power steering device 13 Intermediate shaft 22 ECU (Electric Control Unit)
23 Motor 24 Reducer 30 Housing 31 Motor housing 32 Warm housing 33 End housing 34 Sensor housing 35 Brackets 39A, 39B Oil seal 40 Holes 51, 71 Ring plate 55 Vent holes 71d Continuous holes

Claims (4)

An electric power steering device that applies rotational force to a shaft placed in the engine room.
The vertical direction of the electric power steering device is defined when the electric power steering device is mounted on the vehicle.
The electric power steering device is

A motor that applies the rotational force of the shaft and
A speed reducer that applies the rotation of the motor to the shaft after reducing the rotation speed, and
A housing through which the shaft penetrates in the vertical direction and has an internal space for accommodating the motor and the speed reducer.
An opening provided at the upper end of the housing for inserting the shaft, and
The first sealing member that seals the gap with the shaft and
An opening provided at the lower end of the housing for inserting the shaft, and a second sealing member for sealing the gap between the shaft and the shaft.
A sealing plug that allows gas to permeate and does not allow liquid to permeate,
With
The lower end of the housing
The upper surface of the housing facing the internal space and
The lower surface facing the external space of the housing and
Including
The housing is
A hole that penetrates the upper surface and the lower surface and opens downward on the lower surface.
Including
An electric power steering device in which the sealing plug closes the hole. The electric power steering device according to claim 1.
The shaft is an electric power steering device which is an intermediate shaft. The electric power steering device according to claim 1 or 2, further comprising.
A bracket that covers the opening of the hole in the lower surface at the lower end.
Equipped with an electric power steering device. The electric power steering device according to any one of claims 1 to 3.
The housing is
A worm housing that houses the worms that make up the reducer, and
An end housing that is located adjacent to the bottom of the worm housing and covers the lower end face of the worm housing.
With
The worm housing is
An annular plate portion in which the lower surface constitutes the lower end surface of the worm housing and the upper surface faces the space for accommodating the worm.
Vents that penetrate the upper and lower surfaces of the annular plate portion,
With
The end housing
A continuous hole that penetrates the upper and lower ends of the end housing,
With
An electric power steering device in which the holes are formed by the continuous arrangement of the ventilation holes and the continuous holes.

Images