JP2015093512A - Steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering device in which sealing performance between a reduction gear housing and a motor housing can be secured.SOLUTION: An electric power steering device 1 comprises a motor 6 the surrounding of which is covered by a motor housing 61 and a reduction gear housing 13 which houses a reduction gear 9 inside, and the motor housing 61 is fitted to the outer wall 14 of the reduction gear housing 13. The output shaft 60 of the motor 6 is arranged so as to extend to the inside of the reduction gear housing 13 through an open hole 15 formed at the outer wall 14 of the reduction gear housing 13. At the motor housing 61, formed is a spigot part 66 which extends to the inside of the open hole 15, separated from the inner wall surface of the open hole 15 by an annular gap. At the gap between the inner periphery surface of the open hole 15 and the outer periphery surface of the spigot part 66, arranged is an annular packing 70 which has elasticity in the own radial direction.

Description

  The present invention relates to a steering device.

  Conventionally, as one of the steering devices, there is known an electric power steering device that applies assist force to a steering mechanism by converting motor torque into axial force of a steered shaft via a speed reducer and a ball screw mechanism. Yes. As this type of electric power steering apparatus, as seen in, for example, Patent Document 1, there is a so-called rack parallel type electric power steering apparatus in which an output shaft of a motor is arranged in parallel to a steered shaft. The electric power steering apparatus includes a pair of pulleys attached to an output shaft of a motor and a ball screw mechanism, and a speed reducer comprising an endless belt wound around each pulley. The rotation is transmitted to the ball screw mechanism through the speed reducer. The motor housing is fastened and fixed to the reduction gear housing by bolts. A packing made of an O-ring is interposed between the reduction gear housing and the motor housing, and the sealing property between the housings is secured by this packing.

JP 2005-349861 A

  In such an electric power steering device, it is important to appropriately set the belt tension in order to ensure the transmission efficiency of the motor torque. Therefore, conventionally, for example, when the motor housing is assembled to the reducer housing, the motor housing is brought into contact with the reducer housing and the bolts are temporarily fixed, and then the motor housing is perpendicular to the steered shaft with respect to the reducer housing. A method is used in which the tension of the belt is adjusted by shifting the belt. In this belt tension adjustment method, the motor housing is fixed to the reduction gear housing by tightening the bolts after the belt tension adjustment is completed.

  By the way, if the motor housing is shifted with respect to the reduction gear housing during belt tension adjustment, a frictional force acts on the packing interposed between the reduction gear housing and the motor housing. If the position of the packing is shifted by this frictional force and the packing is caught between the reduction gear housing and the motor housing, the sealing function of the packing may be impaired, and the sealing performance between the housings may be deteriorated.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a steering device capable of ensuring a sealing property between a reduction gear housing and a motor housing.

  In order to solve the above problems, a motor whose periphery is covered by a motor housing, a drive pulley attached to an output shaft of the motor, a driven pulley attached to a steering mechanism of a vehicle, and the drive pulley and the driven pulley A speed reducer that has an endless belt wound around the motor, and transmits rotation of the output of the motor to the steering mechanism via the drive pulley, the belt, and the driven pulley, and the speed reducer inside A reduction gear housing for receiving the motor, wherein the motor housing is attached to an outer wall of the reduction gear housing, and an output shaft of the motor passes through a through hole formed in the outer wall of the reduction gear housing. In the steering device arranged to extend inside, the motor housing is provided between the inner peripheral surface of the through hole and the motor housing. Separating an annular gap forms a spigot portion which extends into the interior of the through hole, wherein the annular gap, and the fitting the annular packing having elasticity radially of its own.

  If the packing is fitted between the inner peripheral surface of the through hole of the reduction gear housing and the outer peripheral surface of the spigot portion of the motor housing as in this configuration, the sealing performance between the housings can be ensured. . On the other hand, when the configuration as described above is adopted, when the motor housing is shifted with respect to the reduction gear housing during belt tension adjustment, the central axis of the through hole of the reduction gear housing and the central axis of the spigot portion of the motor housing are There is a possibility of deviation. This is a factor causing a wide gap portion and a narrow gap portion in the gap formed between the outer peripheral surface of the spigot portion and the inner peripheral surface of the through hole. In this regard, if the packing has elasticity in the radial direction as in the above-described configuration, the packing is deformed following the deformation of the gap, so that the sealing performance can be more accurately ensured.

About the said steering apparatus, it is preferable that the said packing consists of a shape which has a pair of opposing part which opposes the said radial direction.
According to this configuration, the packing is easily elastically deformed in the radial direction by being deformed so that the pair of opposed portions are opened or deformed so as to be closed. Thereby, since it becomes easier to follow the deformation | transformation of the above gaps, a sealing performance can be improved.

Specifically, the packing is preferably any one of Y packing, U packing, and V packing.
According to this configuration, it is possible to easily realize a packing having elasticity in the radial direction.

In the steering device, an engagement groove with which the packing is engaged is preferably formed on at least one of the inner peripheral surface of the through hole and the outer peripheral surface of the spigot portion.
According to this structure, since the position shift of packing can be suppressed, high sealing performance can be ensured.

  According to this steering device, it is possible to ensure the sealing performance between the reduction gear housing and the motor housing.

Sectional drawing which shows the cross-sectional structure about one Embodiment of an electric power steering device. Sectional drawing which shows the cross-sectional structure of the assist mechanism periphery about the electric power steering apparatus of embodiment. Sectional drawing which shows the cross-section around the assist mechanism about the modification of an electric power steering device. Sectional drawing which shows the cross-section around the assist mechanism about the other modification of an electric power steering device. Sectional drawing which shows the cross-section around the assist mechanism about the other modification of an electric power steering device.

  Hereinafter, an embodiment of the steering device will be described. The steering device of the present embodiment is an electric power steering device that applies assist force to a steering mechanism by a motor.

  As shown in FIG. 1, the electric power steering apparatus 1 includes a steering mechanism 4 that turns a steered wheel 3 based on an operation of a driver's steering wheel 2 and an assist mechanism 5 that assists the driver's steering operation. ing.

  The steering mechanism 4 includes a steering shaft 40 that serves as a rotating shaft of the steering wheel 2. The steering shaft 40 includes a column shaft 41 connected to the steering wheel 2, an intermediate shaft 42 connected to the lower end portion of the column shaft 41, and a pinion shaft 43 connected to the lower end portion of the intermediate shaft 42. A lower end portion of the pinion shaft 43 is connected to a rack shaft 45 as a steered shaft via a rack and pinion mechanism 44. In the steering mechanism 4, the column shaft 41, the intermediate shaft 42, and the pinion shaft 43 rotate integrally as the driver operates the steering wheel 2. The rotational motion of the pinion shaft 43 is converted into a reciprocating linear motion in the axial direction of the rack shaft 45 via the rack and pinion mechanism 44. The reciprocating linear motion of the rack shaft 45 in the axial direction is transmitted to the tie rod 47 via the ball joints 46 connected to both ends thereof, and the tie rod 47 is driven. When the turning angle of the steered wheels 3 changes based on the driving of the tie rod 47, the traveling direction of the vehicle is changed.

  The assist mechanism 5 is provided on the rack shaft 45. The assist mechanism 5 includes a motor 6 and a power transmission mechanism 7. The output shaft 60 of the motor 6 is disposed in parallel with the central axis of the rack shaft 45. That is, the electric power steering apparatus 1 of this embodiment is a rack parallel type electric power steering apparatus. The power transmission mechanism 7 includes a ball screw mechanism 8 that is integrally attached around the rack shaft 45 and a speed reducer 9 that transmits the rotation of the output shaft 60 of the motor 6 to the ball screw mechanism 8. The power transmission mechanism 7 converts the rotational force of the output shaft 60 of the motor 6 into a force in the axial direction of the rack shaft 45 via the speed reducer 9 and the ball screw mechanism 8 and applies the force to the rack shaft 45. The driver's steering operation is assisted by the force applied from the motor 6 to the rack shaft 45 through the power transmission mechanism 7.

  The outer periphery of the pinion shaft 43, the rack shaft 45, and the power transmission mechanism 7 is covered with the rack housing 10. The rack housing 10 includes a first housing 11 and a second housing 12 that are divided in the axial direction of the rack shaft 45 in the vicinity of the power transmission mechanism 7 and is configured by connecting them together. A speed reducer housing 13 that accommodates a part of the speed reducer 9 is formed at the bottom of a portion of the rack housing 10 that accommodates the power transmission mechanism 7 so as to protrude downward in the vertical direction. An annular through hole 15 is formed in the outer wall 14 of the speed reducer housing 13, and the output shaft 60 of the motor 6 extends to the inside of the speed reducer housing 13 through the through hole 15 and is connected to the speed reducer 9.

  Next, the structures of the ball screw mechanism 8 and the speed reducer 9 will be described in detail with reference to FIG. In FIG. 2, the central axis of the rack shaft 45 is “m1”, the central axis of the output shaft 60 of the motor 6 is “m2”, and the central axis of the through hole 15 formed in the speed reducer housing 13 is “m3”. Show.

  As shown in FIG. 2, a thread groove 48 is formed on the outer peripheral surface of the rack shaft 45. The ball screw mechanism 8 has a cylindrical nut 81 that is screwed into the thread groove 48 of the rack shaft 45 via a plurality of balls 80. The nut 81 is supported by a ball bearing 82 so as to be rotatable with respect to the rack housing 10. A thread groove 83 is formed on the inner peripheral surface of the nut 81. A spiral rolling path R is formed by a space surrounded by the thread groove 83 of the nut 81 and the thread groove 48 of the rack shaft 45. In addition, a circulation path (not shown) that short-circuits the two locations of the rolling path R is formed inside the nut 81.

  In the ball screw mechanism 8 having such a structure, when the nut 81 rotates relative to the rack shaft 45, the ball 80 receives a load (frictional force) from the nut 81 and the rack shaft 45 and rolls in the rolling path R. Move. At this time, the ball 80 circulates infinitely in the rolling path R through a circulation path formed inside the nut 81. Due to the rolling of the balls 80, the torque applied to the nut 81 is transmitted to the rack shaft 45, and the rack shaft 45 moves in the axial direction with respect to the nut 81. That is, the ball screw mechanism 8 applies an axial force to the rack shaft 45 based on the rotation of the nut 81.

  The speed reducer 9 includes a drive pulley 90 that is integrally attached to the output shaft 60 of the motor 6, a driven pulley 91 that is integrally attached to the outer peripheral surface of the nut 81, and endlessly wound around the pulleys 90 and 91. A belt 92 is formed. The speed reducer 9 transmits the rotation of the driving pulley 90 to the nut 81 via the belt 92 and the driven pulley 91.

  In the assist mechanism 5 including the ball screw mechanism 8, the speed reducer 9, and the motor 6, when the output shaft 60 of the motor 6 rotates based on the energization of the motor 6, the output shaft 60 of the motor 6 is integrated. The drive pulley 90 rotates. As a result, the drive pulley 90 integrally rotates the driven pulley 91 and the nut 81 via the belt 92. An axial force is applied to the rack shaft 45 based on the rotation of the nut 81.

Next, the attachment structure of the motor 6 to the reduction gear housing 13 will be described.
As shown in FIG. 2, the periphery of the motor 6 is covered with a motor housing 61. At the end of the motor housing 61 on the output shaft 60 side, a flange portion 62 having a cylindrical shape around the axis m2 is formed, and the end surface 63 in the axial direction of the flange portion 62 is the outer wall 14 of the speed reducer housing 13. Abut. The flange portion 62 is formed with a plurality of bolt holes 64 penetrating in the axial direction. The motor housing 61 is fixed to the reduction gear housing 13 by fastening the bolt 65 inserted into the bolt hole 64 to the outer wall 14 of the reduction gear housing 13.

  The motor housing 61 is formed with an inlay portion 66 extending from the end surface 63 of the flange portion 62 into the through hole 15 of the speed reducer housing 13. The inlay portion 66 is formed in a cylindrical shape around the axis m2. The inlay portion 66 includes a base end portion 66a formed so as to extend from the flange portion 62, and a reduced diameter portion 66b formed so as to extend from the end surface of the base end portion 66a and having an outer diameter smaller than that of the base end portion 66a. Thus, a step surface 66c is provided at the boundary between the base end portion 66a and the reduced diameter portion 66b. An annular first packing 70 is fitted in an annular gap formed between the outer peripheral surface of the reduced diameter portion 66 b of the inlay portion 66 and the inner peripheral surface of the through hole 15 of the speed reducer housing 13. . As shown in an enlarged view in FIG. 2, the first packing 70 includes an extending portion 71 extending in the axial direction in a cross section orthogonal to the central axis, and a first V-shaped branch from one end portion of the extending portion 71. It consists of what is called Y packing which has a pair of opposing parts 72 and 73 which oppose the radial direction of 1 packing 70. FIG. The other end portion of the extending portion 71 opposite to the one end portion where the facing portions 72 and 73 are formed is in contact with the step surface 66 c of the spigot portion 66. The pair of facing portions 72 and 73 are in contact with the inner peripheral surface of the through hole 15 and the outer peripheral surface of the spigot portion 66, respectively.

An annular groove 17 is formed on the contact surface 16 of the reduction gear housing 13 with the motor housing 61, and a second packing 74 made of an O-ring is disposed in the groove 17.
Hereinafter, the operation and effect of the electric power steering apparatus 1 of the present embodiment will be described.

  (1) In the electric power steering apparatus 1 of the present embodiment, when the motor 6 is assembled to the reduction gear housing 13, first, the motor housing 61 is brought into contact with the outer wall 14 of the reduction gear housing 13 to temporarily fix the bolt 65. . Thereafter, the motor housing 61 is shifted with respect to the reduction gear housing 13 in the directions indicated by arrows a1 and a2 in the drawing, that is, between the center axis m1 of the rack shaft 45 and the center axis m2 of the output shaft 60 of the motor 6. The tension of the belt 92 is adjusted by shifting in the direction in which the distance of the belt changes. At this time, if the second packing 74 is caught between the reduction gear housing 13 and the motor housing 61, the sealing performance of the second packing 74 may be deteriorated. In this regard, in the electric power steering apparatus 1 of the present embodiment, even when the sealing performance of the second packing 74 is lowered, the sealing performance between the reduction gear housing 13 and the motor housing 61 is maintained by the first packing 70. Can do.

  (2) When adjusting the belt tension, for example, when the motor housing 61 is shifted in the direction indicated by the arrow a2 with respect to the speed reducer housing 13 in order to increase the tension of the belt 92, the center axis m2 of the spigot portion 66 becomes the through hole 15. Is shifted in the direction indicated by the arrow a2 with respect to the central axis m3. In this case, the gap formed between the outer peripheral surface of the spigot portion 66 and the inner peripheral surface of the through hole 15 is narrower on the side indicated by the arrow a2, and is wider on the opposite side indicated by the arrow a1. Become. In this regard, the first packing 70 of the present embodiment is deformed so that the pair of facing portions 72 and 73 are closed at the portion where the gap is narrowed, and the pair of facing portions 72 and 73 are expanded at the portion where the gap is widened. Therefore, it is possible to follow the deformation of the gap. Therefore, the sealing property can be ensured more accurately.

In addition, the said embodiment can also be implemented with the following forms.
-The shape of the 1st packing 70 can be changed suitably. For example, as shown in FIG. 3, the first packing 70 may be a so-called U-packing having a pair of facing portions 75 and 76 that face each other in the radial direction of the first packing 70 in a cross section orthogonal to the central axis. . Alternatively, as shown in FIG. 4, the first packing 70 may be a so-called V packing having a pair of facing portions 77 and 78 that face each other in the radial direction of the first packing 70 in a cross section orthogonal to the central axis. Good. In short, the first packing 70 may be an annular packing having elasticity in its radial direction.

  As shown in FIG. 5, an engagement groove 18 that engages with one opposing portion 72 of the first packing 70 may be formed on the inner peripheral surface of the through hole 15 of the speed reducer housing 13. Further, an engagement groove 67 that engages with the other facing portion 73 of the first packing 70 may be formed on the outer peripheral surface of the spigot portion 66 of the motor housing 61. Thereby, since the position shift of the 1st packing 70 is suppressed, sealing performance can be ensured exactly. In addition, even when the first packing 70 is made of Y packing, including at least one of the Y packing, at least the inner peripheral surface of the through hole 15 of the reduction gear housing 13 and the outer peripheral surface of the spigot portion 66 of the motor housing 61 are used. If an engagement groove with which the first packing 70 is engaged is formed on one side, the same effect can be obtained.

-The 2nd packing 74 may be abbreviate | omitted and the sealing performance between the reduction gear housing 13 and the motor housing 61 may be ensured only with the 1st packing 70. FIG.
The seal structure between the speed reducer housing 13 and the motor housing 61 shown in the above embodiment and its modifications is not limited to the rack parallel type electric power steering device 1 but can be applied to other steering devices. . For example, the present invention can be applied to various steering devices that apply assist force from a motor to a steering mechanism via a speed reducer, such as an electric power steering device that applies assist force to the column shaft 41 and a steer-by-wire type steering device.

  DESCRIPTION OF SYMBOLS 4 ... Steering mechanism, 6 ... Motor, 9 ... Reducer, 13 ... Reducer housing, 15 ... Through-hole, 18, 67 ... Engagement groove, 60 ... Output shaft, 61 ... Motor housing, 66 ... Inlay part, 70 ... Packing, 72 to 77 ... facing portion, 90 ... driving pulley, 91 ... driven pulley, 92 ... belt.

Claims (4)

A motor surrounded by a motor housing;
A drive pulley attached to an output shaft of the motor; a driven pulley attached to a steering mechanism of a vehicle; and an endless belt wound around the drive pulley and the driven pulley; and rotation of the output of the motor A reduction gear that transmits the driving pulley, the belt, and the driven pulley to the steering mechanism;
A reducer housing that houses the reducer therein,
The motor housing is attached to an outer wall of the reducer housing;
In the steering apparatus, the output shaft of the motor is arranged to extend into the reduction gear housing through a through hole formed in an outer wall of the reduction gear housing.
The motor housing is formed with an inlay portion extending into the through hole with an annular gap between the inner peripheral surface of the through hole,
A steering device, wherein an annular packing having elasticity in its radial direction is fitted into the annular gap. The steering apparatus according to claim 1, wherein
The packing device has a shape having a pair of opposed portions opposed to each other in the radial direction. The steering apparatus according to claim 2, wherein
The steering device according to claim 1, wherein the packing is any one of a Y packing, a U packing, and a V packing. In the steering device according to any one of claims 1 to 3,
The steering device according to claim 1, wherein an engagement groove for engaging the packing is formed on at least one of an inner peripheral surface of the through hole and an outer peripheral surface of the spigot portion.