JP6349770B2 - Steering device - Google Patents

Description

  The present invention relates to a steering device.

  Conventionally, as described in Patent Document 1, for example, there is a steering device that decelerates rotation of a motor by a belt transmission mechanism and converts the decelerated rotation into axial movement of the rack shaft by a ball screw mechanism provided on the rack shaft. Are known. The belt transmission mechanism includes a driving pulley provided on a rotating shaft of a motor, a driven pulley provided on a ball nut fitted to a ball screw portion of the rack shaft via a large number of balls, and a belt spanned between these pulleys. And have. Steering is assisted by the rack shaft moving in the axial direction along with the rotation of the ball nut through the drive of the motor. The belt transmission mechanism, the ball screw mechanism, and the rack shaft are each accommodated in the housing.

JP 2013-159203 A (paragraph [0012], FIG. 2)

  The housing of the steering device of Patent Document 1 is assembled so as to be separable into a left housing and a right housing along the axial direction of the rack shaft at a portion where the belt transmission mechanism and the ball screw mechanism are accommodated. The left housing and the right housing are connected to each other by a plurality of bolts at their upper and lower portions.

  When assembling the steering apparatus, it is necessary to assemble the belt transmission mechanism and the ball screw mechanism, respectively, while strictly managing the gap in the axial direction with the left housing or the right housing. For this reason, it is very difficult to assemble.

  An object of the present invention is to provide a steering apparatus that can simplify an assembling operation.

  A steering device that can achieve the above object is a steering shaft that linearly moves within a housing, a motor that is provided in the housing, and a rotary motion that is provided inside the housing and converts the rotational motion of the motor into linear motion of the steering shaft A power conversion mechanism. The housing includes a first part that houses the power conversion mechanism in a manner that it is exposed in the radial direction of the steered shaft, and a second part that is attached to the first part and covers the exposed part of the power conversion mechanism. , Has.

  According to this configuration, the first portion and the second portion of the housing can be separated from each other in the radial direction of the steered shaft. The power conversion mechanism is provided in the first portion of the housing so as to be exposed in the radial direction of the steered shaft. It is also possible to assemble the components of the power conversion mechanism while viewing from the radial direction of the steered shaft. . For this reason, it becomes easier to assemble the power conversion mechanism than the conventional configuration in which the housing is separated in the axial direction of the steered shaft. As a result, the assembly work of the steering device is also simplified.

  In the above steering device, when the housing is mounted on the vehicle body on the premise that the first part and the second part are assembled with their open end faces butted in the radial direction of the turning shaft. The boundary surface between the first part and the second part is set in a direction along a direction that does not coincide with the direction of the radial component around the turning axis of the load applied to the turning shaft. Is preferred.

  According to this configuration, it is difficult to apply a force in a direction in which the first portion and the second portion of the housing slide along the boundary surface. For this reason, the assembly | attachment state of the 1st part of a housing and a 2nd part is maintained suitably.

  In the above steering apparatus, the first portion and the second portion are premised on the assumption that the first end portion and the second portion are assembled with their open end faces butted in the radial direction of the steered shaft. The boundary surface with the portion 2 preferably includes the axis of the steered shaft.

  According to this configuration, when viewed from the axial direction of the steered shaft, half of the power conversion mechanism is covered with the first portion and the remaining half is covered with the second portion. That is, in a state where the second part is not assembled, the power conversion mechanism can be assembled with half of the mechanism exposed. For this reason, the assembly work of the steering device including the power conversion mechanism is further simplified.

  In the above steering apparatus, the first portion and the second portion constitute a cylindrical portion extending along the axial direction of the steered shaft, and a cylindrical sleeve is provided in the cylindrical portion in the axial direction of the steered shaft. You may make it press-fit along.

  According to this configuration, the outer periphery of the cylindrical portion constituted by the first portion and the second portion is maintained in a state of being tightened by the cylindrical sleeve. For this reason, the assembly | attachment state of a 1st part and a 2nd part is maintained suitably.

  According to the present invention, the assembly operation of the steering device can be simplified.

The front view which shows the principal part of the steering device in one embodiment. The side view which looked at the steering apparatus in one Embodiment from the rack axial direction. The front view which shows the power conversion mechanism of the steering device in one embodiment. The side view which looked at the steering device in one embodiment from the rack axis direction. The side view which looked at the steering apparatus in other forms from the rack axial direction. The perspective view which decomposed | disassembled the housing of the steering device in another form. The perspective view which shows the principal part of the steering apparatus in other embodiment. The front view which shows the principal part of the steering apparatus in other embodiment.

Hereinafter, an embodiment of the steering device will be described.
As shown in FIG. 1, an EPS (electric power steering apparatus) 10 has a housing 11 fixed to a vehicle body (not shown). The housing 11 has a cylindrical main body 12 extending in the left-right direction of the vehicle body (left-right direction in FIG. 1), and a mechanism housing portion 13 provided at a portion near the left end of the main body 12.

  A rack shaft 14 is inserted into the main body 12. Wheels (not shown) are connected to both ends of the rack shaft 14 via ball joints (not shown). The direction of the wheel is changed by the rack shaft 14 moving in the axial direction in conjunction with the operation of a steering wheel (not shown).

  The upper part of the cylindrical portion having a larger diameter than the main body 12 extends upward in the mechanism housing portion 13. A steering assist motor 15 is fixed to the upper right side wall of the mechanism housing portion 13. The axis of the motor 15 and the axis of the rack shaft 14 are parallel to each other. The rotational motion of the motor 15 is converted into linear motion of the rack shaft 14 via a power conversion mechanism (not shown) accommodated in the mechanism accommodating portion 13. That is, the operation of the rack shaft 14 is assisted by the motor 15 to assist the steering operation.

  As shown in FIG. 2, when the housing 11 is viewed from the axial direction of the rack shaft 14, the mechanism housing portion 13 is divided into two in the radial direction of the rack shaft 14. In this example, the mechanism accommodating portion 13 is divided into a first portion 21 in the left half and a second portion 22 in the right half in FIG. The first portion 21 is a portion formed integrally with the main body 12. The second portion 22 is a portion that is separably attached to the first portion 21. The second portion 22 is fixed to the first portion 21 with a plurality of bolts 25 in a state where the opening end surface 22 a of the second portion 22 is abutted against the opening end surface 21 a of the first portion 21. Each bolt 25 extends along a direction orthogonal to the plane including the axis O of the rack shaft 14.

  Here, the dividing surface 23 of the housing 11 (the boundary surface between the first portion 21 and the second portion 22) is preferably set as follows. For example, when the housing 11 is mounted on the vehicle body, the dividing surface 23 does not coincide with the direction of the radial component F centering on the axis (rack axis) O of the rack shaft 14 of the load applied to the rack shaft 14 from a tie rod (not shown). It is preferable to provide in a direction along the direction (vertical direction in FIG. 2). In other words, the dividing direction of the first portion 21 and the second portion 22 is preferably set in a direction different from the radial component F (vertical direction in FIG. 2). In the present example, when viewed from the axial direction of the rack shaft 14, the first portion 21 and the second portion 22 exhibit surface symmetry about the dividing plane 23. The dividing surface 23 includes the axis O of the rack shaft 14.

As shown in FIG. 3, the power conversion mechanism 30 is exposed in the radial direction of the rack shaft 14 in a state where the second portion 22 is removed from the first portion 21.
The power conversion mechanism 30 includes a belt transmission mechanism 40 and a ball screw mechanism 50. The belt transmission mechanism 40 transmits the rotational motion of the motor 15 to the ball screw mechanism 50. The ball screw mechanism 50 converts the rotational motion of the motor 15 transmitted through the belt transmission mechanism 40 into linear motion of the rack shaft 14.

  The ball screw mechanism 50 includes a ball screw portion 51 provided on a part of the rack shaft 14, a cylindrical ball nut 52, and a large number of balls 53. The ball screw portion 51 is a portion where the ball screw groove 14 a is formed on the outer peripheral surface of the rack shaft 14. The ball screw portion 51 is threadably engaged with the ball nut 52 via a large number of balls 53. Each ball 53 rolls between the ball nut 52 and the ball screw portion 51 as the ball nut 52 rotates. A double row ball bearing 54 is fixed to the outer peripheral surface of the ball nut 52. The ball nut 52 is supported via a ball bearing 54 so as to be rotatable with respect to the inner peripheral surface of the mechanism accommodating portion 13 (more precisely, a cylindrical portion thereof).

  The belt transmission mechanism 40 includes a cylindrical driving pulley 41 that is a driving vehicle, a cylindrical driven pulley 42 that is a driven vehicle, and an endless belt 43. The drive pulley 41 is fixed to the output shaft 15 a of the motor 15. The driven pulley 42 is fixed to the outer peripheral surface of the ball nut 52. The belt 43 is stretched between the driving pulley 41 and the driven pulley 42. Accordingly, the rotation of the motor 15 is transmitted to the ball nut 52 via the drive pulley 41, the belt 43 and the driven pulley 42.

Now, the procedure for assembling the EPS 10 is as follows.
As shown in FIG. 4, first, the motor 15 is attached to the first portion 21 with the second portion 22 removed, and the components of the power conversion mechanism 30 are assembled. The power conversion mechanism 30 provided in the first portion 21 is maintained in an exposed state in the radial direction of the rack shaft 14. Thereafter, the second portion 22 is attached to the first portion 21. The second portion 22 is brought closer to the first portion 21 from the exposed side of the power conversion mechanism 30. Then, in the radial direction of the rack shaft 14, the plurality of bolts 25 are placed outside the second portion 22 while maintaining the opening end surface 22 a of the second portion 22 in contact with the opening end surface 22 a of the first portion 21 ( It is inserted from the side opposite to the first part 21) and fastened to the first part 21. As a result, the second portion 22 is fixed to the first portion 21. The portion exposed from the first portion 21 in the power conversion mechanism 30 is maintained in a state covered with the second portion 22.

As described above, by dividing the housing 11 (mechanism housing portion 13) into the first portion 21 and the second portion 22 in the radial direction of the rack shaft 14, the following action is obtained.
That is, in the state where the second portion 22 is removed, the entire interior of the first portion 21 where the power conversion mechanism 30 is provided is exposed. Since each component of the power conversion mechanism 30 can be assembled to the exposed portion while visually observing, the assembling work is simple. Further, when the second portion 22 is removed, half of the power conversion mechanism 30 around the rack shaft is exposed. For this reason, after assembling the power conversion mechanism 30 in the first portion 21, the assembled state of the power conversion mechanism 30 or the stored state (such as the number of gaps) with respect to the first portion 21 can be easily confirmed visually. can do. Adjustment work when assembling each component of the power conversion mechanism 30 can also be easily performed while visually observing. Further, the second portion 22 can be attached to the first portion 21 while observing the state of the power conversion mechanism 30 such as the degree of engagement between the drive pulley 41 and the belt 43 or the driven pulley 42 and the belt 43. In addition, for example, it is possible to easily disassemble or adjust the EPS 10 during maintenance.

<Effect of Embodiment>
According to the present embodiment, the following effects can be obtained.
(1) The mechanism accommodating portion 13 is divided into a first portion 21 and a second portion 22 in the radial direction of the rack shaft 14. Unlike the case of assembling each component in the axial direction of the housing 11, each component can be assembled or disassembled while visually observing. For this reason, the assembling work or the disassembling work of the power conversion mechanism 30 can be easily performed.

  (2) When the dividing direction of the mechanism accommodating portion 13 is set to a direction different from the radial load acting on the rack shaft 14, the assembled state of the first portion 21 and the second portion 22 of the mechanism accommodating portion 13 is preferable. Maintained. This is because it becomes difficult to apply a force in a direction in which the first portion 21 and the second portion 22 of the housing 11 slide along the dividing surface 23.

  (3) The dividing surface 23 between the first portion 21 and the second portion 22 is set so as to include the axis O of the rack shaft 14. By setting the dividing surface 23 in this way, when the housing 11 is viewed from the axial direction of the rack shaft 14, half of the power conversion mechanism 30 is covered by the first portion 21 and the other half is covered by the second portion 22. It will be. For this reason, in a state where the second portion 22 is removed, the power conversion mechanism 30 can be assembled in a state where half of the power conversion mechanism 30 is exposed. Therefore, the assembly work of the EPS 10 including the power conversion mechanism 30 becomes easier.

  (4) When the housing 11 is divided into two parts in the axial direction of the rack shaft 14, a plurality of bolt insertion parts and bolt fastening parts for fastening the divided housings in the axial direction are provided on the peripheral surfaces of the two divided housings. There is a need. In this example, it is not necessary to project such insertion part and tightening part in the radial direction of the housing 11. For this reason, it is possible to reduce the protruding portion appearing on the surface of the housing 11. It becomes easy to mount EPS10 in a vehicle.

<Other embodiments>
In addition, you may implement the said embodiment as follows.
A sealing device (seal) such as rubber packing or liquid packing may be provided between the first portion 21 and the second portion 22. Water, dust and the like are prevented from entering the housing 11.

  In this example, when the housing 11 is viewed from the axial direction of the rack shaft 14, the mechanism housing portion 13 is equally divided into two around the axis of the rack shaft 14. For example, as shown in FIG. 5, it is sufficient that the second portion 22 can be separated from the first portion 21 in the radial direction of the rack shaft 14.

  -As shown in FIG. 6, you may provide the fitting part using an uneven | corrugated relationship between the 1st part 21 and the 2nd part 22. As shown in FIG. For example, a plurality of holes 61 are provided in the opening end surface 21 a of the first portion 21, while the same number of protrusions 62 as the holes 61 are provided in the opening end surface 22 a of the second portion 22. The protrusion 62 may use a pin or the like. The second portion 22 is attached to the first portion 21 so that the protrusion 62 is fitted into the hole 61. By fitting the protrusion 62 into the hole 61, the mounting position of the second portion 22 with respect to the first portion 21 is difficult to shift. For this reason, the attachment position of the 2nd part 22 with respect to the 1st part 21 is maintained suitably. Only one set of holes 61 and protrusions 62 may be provided, or three or more sets may be provided.

  As shown in FIG. 7, when a cylindrical portion 13a as a part of the mechanism accommodating portion 13 is provided at a portion opposite to the main body 12 of the mechanism accommodating portion 13, a cylindrical sleeve 71 is press-fitted into the cylindrical portion 13a. May be. At this time, as shown in FIG. 8, the sleeve 71 is preferably press-fitted to a position corresponding to the ball bearing 54 provided inside the mechanism housing portion 13. If it does in this way, the attachment state of the 2nd part 22 to the 1st part 21 will be maintained more suitably. Further, a radial load applied to the housing 11 via the rack shaft 14 can be suitably received.

  When the EPS 10 is mounted on the vehicle body, the dividing surface 23 of the mechanism housing portion 13 may be set in a direction that does not coincide with the radial load acting on the rack shaft 14. In such a case, the sleeve 71 shown in FIGS. 7 and 8 is particularly effective.

  In this example, a so-called rack parallel type electric power steering device is given as an example, but rack direct type (RD-EPS) or dual pinion type (DP-EPS) EPS is similar to the housing 11 of this example. It is possible to apply a configuration.

  In this example, the electric power steering device that assists the operation of the rack shaft 14 that linearly moves in conjunction with the steering operation by using the rotational force of the motor 15 is described as an example, but it is applied to a steer-by-wire (SBW). You can also. The steer-by-wire is a steering device that does not have a mechanical connection between the steering wheel and the steered wheel, and transmits an operation of the steering wheel to the steered actuator by an electric signal. You may employ | adopt the power conversion mechanism 30 of this example as this steering actuator. The steered actuator converts the rotational motion of the motor into a linear motion of the steered shaft (ball screw shaft). It should be noted that, when embodied in steer-by-wire, it can be embodied not only as a front wheel steering device but also as a rear wheel steering device or a four wheel steering device (4WS).

Next, a technical idea that can be grasped from the above embodiment will be added below.
The power conversion mechanism includes a prime mover that rotates about an axis that extends along the axis of the steered shaft (steering axis) as the motor is driven, and a screw that is screwed onto the steered shaft via a number of balls. A ball nut that is rotatably supported with respect to the inner peripheral surface of the housing via a bearing, and a driven vehicle that is fitted to the outer periphery of the ball nut and transmits the rotation of the prime mover to the ball nut. A belt stretched between the driving vehicle and the driven vehicle, and the cylindrical sleeve is press-fitted to a position corresponding to the bearing. According to this configuration, the radial load applied to the steered shaft is also received by the cylindrical sleeve.

  DESCRIPTION OF SYMBOLS 10 ... Steering device, 11 ... Housing, 13a ... Cylindrical part, 14 ... Rack shaft (steering shaft), 15 ... Motor, 30 ... Power conversion mechanism, 21 ... 1st part, 22 ... 2nd part, 23 ... Dividing surface (boundary surface), 71 ... sleeve, O ... rack axis (steering axis).

Claims (5)

A steering shaft that linearly moves within the housing, a motor provided in the housing, and a power conversion mechanism that is provided inside the housing and converts the rotational motion of the motor into linear motion of the steering shaft,
Said housing, said first portion for housing in a manner to expose the power conversion mechanism in the radial direction of the steering shaft, the second covering the exposed portion of the first mounted to portion the power conversion mechanism And having a portion ,
The power conversion mechanism includes a belt transmission mechanism including a driving pulley, a driven pulley, and an endless belt, and a ball screw mechanism.
A steering device in which the power conversion mechanism in an assembled state is exposed from the first portion in a state where the second portion is removed .   A steering shaft that linearly moves within the housing, a motor provided in the housing, and a power conversion mechanism that is provided inside the housing and converts the rotational motion of the motor into linear motion of the steering shaft,
  The housing includes a first part that accommodates the power conversion mechanism in a manner that it is exposed in a radial direction of the steered shaft, and a second part that is attached to the first part and covers the exposed part of the power conversion mechanism. And having a portion,
  When the housing is mounted on the vehicle body on the premise that the first part and the second part are assembled with their open end faces butted in the radial direction of the turning shaft, the first part And the second part is a steering device that is set in a direction along a direction that does not coincide with the direction of the radial component around the turning axis of the load applied to the turning shaft. The steering apparatus according to claim 1, wherein
When the housing is mounted on the vehicle body on the premise that the first part and the second part are assembled with their open end faces butted in the radial direction of the turning shaft, the first part And the second part is a steering device that is set in a direction along a direction that does not coincide with the direction of the radial component around the turning axis of the load applied to the turning shaft. In the steering device according to any one of claims 1 to 3 ,
Boundary between the first part and the second part on the premise that the first part and the second part are assembled with their open end faces butted in the radial direction of the steered shaft The surface is a steering device that includes the axis of the steered shaft. In the steering device according to any one of claims 1 to 4 ,
The first portion and the second portion constitute a cylindrical portion extending along the axial direction of the steered shaft, and a cylindrical sleeve is press-fitted along the axial direction of the steered shaft into the cylindrical portion. Steering device.