JP2019085072A - Steering device - Google Patents

Abstract

To provide a steering device that can be readily manufactured and reduce the number of components.SOLUTION: A steering device includes: a housing; a rack penetrating through the housing; a bushing holder having an outside diameter that is constant across the whole length in an axial direction of the rack, and fitted to an inner peripheral surface of the housing; a bushing fitted to an inner peripheral surface of the bushing holder and coming into contact with the rack; and a rack flange attached to the rack and facing the bushing holder in an axial direction, where an end surface of the bushing holder comes into contact with the housing.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a steering device.

  The vehicle is provided with a steering device as a device for transmitting an operation of a steering wheel of an operator (driver) to the wheels. In a rack and pinion type steering device, a pinion connected to an input shaft meshes with a rack, and the rack moves in the left and right direction of the vehicle. Movement of the rack changes the orientation of the wheel. For example, Patent Document 1 describes an example of a rack and pinion type steering apparatus. As shown in Patent Document 1, the rack is supported by the housing via a bush.

JP, 2015-189378, A

  By the way, the distance that the rack can move needs to be regulated. For this reason, a stopper is provided to prevent the rack from moving relative to the housing when the rack moves a predetermined distance. In order to reduce the number of parts, it is desirable for the bush to double as a stopper. However, in the case of the steering apparatus of Patent Document 1, in order to use the bush as a stopper of the rack, the bush needs to be shaped so as to be hooked on the housing. This makes the manufacture of the bush difficult.

  This indication is made in view of the above-mentioned subject, and it aims at providing a steering device which can be manufactured easily and can reduce the number of parts.

  In order to achieve the above object, the steering apparatus according to one aspect of the present disclosure includes a housing, a rack passing through the housing, and an outer diameter that is constant over the entire axial length of the rack and is inside the housing. A bush holder fitted to the circumferential surface, a bush fitted to the inner circumferential surface of the bush holder and in contact with the rack, and a rack flange attached to the rack and facing the bush holder in the axial direction; The end face of the bush holder contacts the housing.

  Since the outer diameter of the bush holder is constant over the entire length in the axial direction, complicated machining on the outer peripheral surface of the bush holder is unnecessary. On the other hand, since the end face of the bush holder is in contact with the housing, movement of the rack is restricted when the rack flange is in contact with the bush holder. Therefore, even if the outer diameter of the bush holder is constant, the bush holder can also serve as a stopper for restricting the movement of the rack. Therefore, the steering device can be easily manufactured and the number of parts can be reduced.

  As a desirable mode of a steering device, it has a buffer member located between the rack flange and the bush holder.

  Thus, the rack flange contacts the bush holder after the buffer member is deformed. For this reason, the impact when the rack flange contacts the bush holder is reduced.

  According to the present disclosure, it is possible to provide a steering device that can be easily manufactured and the number of parts can be reduced.

FIG. 1 is a schematic view of a steering apparatus of the present embodiment. FIG. 2 is a cross-sectional view of the steering gear box of the present embodiment. FIG. 3 is an enlarged cross-sectional view of one end of the steering gear box of the present embodiment. FIG. 4 is an enlarged sectional view of the periphery of the bush unit of the present embodiment. FIG. 5 is a perspective view of the bush unit of the present embodiment. FIG. 6 is a side view of the bush of the present embodiment. FIG. 7 is an enlarged cross-sectional view of the periphery of the bush unit of the first modified example. FIG. 8 is an enlarged cross-sectional view of one end of a steering gear box according to a second modification. FIG. 9 is a perspective view of a bush unit according to a second modification. FIG. 10 is a perspective view of a bush according to a second modification.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited by the following embodiments (hereinafter referred to as embodiments). Further, constituent elements in the following embodiments include those which can be easily conceived by those skilled in the art, those substantially the same, and so-called equivalent ranges. Furthermore, the components disclosed in the following embodiments can be combined as appropriate.

(Embodiment)
FIG. 1 is a schematic view of a steering apparatus of the present embodiment. As shown in FIG. 1, the steering device 80 includes a steering wheel 81, a steering shaft 82, a universal joint 84, a lower shaft 85, a universal joint 86, a pinion shaft 87, a pinion 88, and a steering gear box 1. And an electric motor 93.

  As shown in FIG. 1, the steering wheel 81 is connected to the steering shaft 82. One end of the steering shaft 82 is connected to the steering wheel 81, and the other end of the steering shaft 82 is connected to the universal joint 84. Lower shaft 85 is coupled to steering shaft 82 via universal joint 84. One end of the lower shaft 85 is connected to the universal joint 84, and the other end is connected to the universal joint 86. One end of the pinion shaft 87 is connected to the universal joint 86, and the other end is connected to the pinion 88.

  FIG. 2 is a cross-sectional view of the steering gear box of the present embodiment. FIG. 3 is an enlarged cross-sectional view of one end of the steering gear box of the present embodiment. In FIG. 2, the description of the electric motor 93 and the members attached to the electric motor 93 is omitted. As shown in FIGS. 2 and 3, the steering gear box 1 includes a housing 10, a rack 11, a ball joint 13, a bush unit 5, a buffer member 15, and a rack flange 16.

  The housing 10 is a cylindrical member. The rack 11 passes through the housing 10 and meshes with the pinion 88. The pinion 88 and the rack 11 convert the rotational motion transmitted to the pinion shaft 87 into a linear motion. The rack 11 is connected to a tie rod 89 via a ball joint 13. The movement of the rack 11 in the axial direction of the rack 11 changes the angle of the wheel.

  In the following description, the axial direction of the rack 11 is simply referred to as the axial direction. The direction orthogonal to the axial direction is described as the radial direction. A direction along a tangent of a circle centered on the rotation axis of the rack 11 is described as a circumferential direction.

  The electric motor 93 is, for example, a brushless motor. The electric motor 93 may be a motor including a brush (slider) and a commutator. The electric motor 93 is fixed to the housing 10, for example. The power of the electric motor 93 is transmitted to the rack 11 to move the rack 11 in the axial direction. The torque generated by the electric motor 93 reduces the force required for the operator to move the rack 11. That is, a rack assist type is adopted for the steering device 80.

  As shown in FIG. 1, the steering device 80 includes an ECU (Electronic Control Unit) 90, a torque sensor 94, and a vehicle speed sensor 95. The electric motor 93, the torque sensor 94, and the vehicle speed sensor 95 are electrically connected to the ECU 90. The torque sensor 94 is attached to the pinion 88, for example. The torque sensor 94 outputs the steering torque transmitted to the pinion 88 to the ECU 90 by CAN (Controller Area Network) communication. The vehicle speed sensor 95 detects the traveling speed (vehicle speed) of the vehicle body on which the steering device 80 is mounted. The vehicle speed sensor 95 is provided on the vehicle body and outputs the vehicle speed to the ECU 90 by CAN communication.

  The ECU 90 controls the operation of the electric motor 93. The ECU 90 obtains signals from the torque sensor 94 and the vehicle speed sensor 95, respectively. Electric power is supplied to the ECU 90 from the power supply device 99 (for example, an on-board battery) while the ignition switch 98 is on. The ECU 90 calculates the assist steering command value based on the steering torque and the vehicle speed. The ECU 90 adjusts the power value supplied to the electric motor 93 based on the assist steering command value. The ECU 90 acquires information on the induced voltage from the electric motor 93 or information output from a resolver or the like provided in the electric motor 93. The control of the electric motor 93 by the ECU 90 reduces the force required to operate the steering wheel 81.

  FIG. 4 is an enlarged sectional view of the periphery of the bush unit of the present embodiment. FIG. 5 is a perspective view of the bush unit of the present embodiment. FIG. 6 is a side view of the bush of the present embodiment. As shown in FIG. 3, the bush unit 5 includes a bush holder 51 and a bush 56.

  The bush holder 51 is formed of, for example, metal. The bush holder 51 is a cylindrical member. The outer diameter of the bush holder 51 is constant over the entire axial length. The bush holder 51 is fitted on the inner peripheral surface of the housing 10. For example, the bush holder 51 is pressed into the inside of the housing 10. In the case where the bush holder 51 is manufactured from, for example, a standardized tube, the outer diameter of the bush holder 51 is constant, and therefore, processing on the outer peripheral surface of the tube is unnecessary. For this reason, the bush holder 51 can be easily manufactured. The end surface 511 of the bush holder 51 is in contact with the end surface 101 of the housing 10. The end surface 101 is a plane provided on the inner peripheral surface of the housing 10 and orthogonal to the axial direction.

  As shown in FIG. 4, the bush holder 51 includes a protrusion 513 and a recess 515. The protrusion 513 protrudes from the inner peripheral surface of the bush holder 51 in the radial direction. The protrusion 513 is annular. The inner diameter of the protrusion 513 is larger than the outer diameter of the rack 11. That is, the protrusion 513 is not in contact with the rack 11. The recess 515 is an annular groove provided on the inner peripheral surface of the bush holder 51. The recess 515 is located at the end on the end face 101 side.

  The bush 56 is formed of, for example, a synthetic resin. The bush 56 is a cylindrical member. The bush 56 is fitted on the inner circumferential surface of the bush holder 51. The bush 56 is in contact with the outer peripheral surface of the rack 11. The rack 11 can be smoothly moved in the axial direction by the rack 11 being supported by the bush 56. One end face 561 of the bush 56 is in contact with the end face 101 of the housing 10. The other end face 562 of the bush 56 is in contact with the protrusion 513 of the bush holder 51.

  As shown in FIGS. 4 to 6, the bush 56 includes a plurality of recesses 563, a plurality of O-rings 565, a protrusion 567, a plurality of first slits 568, and a plurality of second slits 569. . The recess 563 is an annular groove provided on the outer peripheral surface of the bush 56. An O-ring 565 is fitted in each recess 563. The O-ring 565 is made of, for example, rubber. The O-ring 565 is in contact with the inner peripheral surface of the bush holder 51. The convex portion 567 is an annular ridge provided on the outer peripheral surface of the bush 56. The convex portion 567 is fitted in the concave portion 515 of the bush holder 51. The convex portion 567 is axially compressed by being sandwiched between the bush holder 51 and the housing 10. Thereby, the bush 56 is positioned. Compared with the case where the convex portion 567 is fitted in the annular groove formed on the inner peripheral surface of the housing 10, complicated processing on the housing 10 is unnecessary.

  As shown in FIG. 6, the first slit 568 extends in the axial direction from the end of the bush 56 on the convex portion 567 side. The plurality of first slits 568 are arranged at equal intervals in the circumferential direction. The second slit 569 extends in the axial direction from the end of the bush 56 opposite to the convex portion 567. The plurality of second slits 569 are arranged at equal intervals in the circumferential direction. As shown in FIG. 6, one second slit 569 is disposed between two adjacent first slits 568 in the circumferential direction. The first slits 568 and the second slits 569 are alternately arranged. The presence of the first slit 568 and the second slit 569 allows the bush 56 to be easily deformed when the bush 56 is inserted into the bush holder 51.

  The bush unit 5 is assembled before being attached to the housing 10. After the bush 56 is inserted into the bush holder 51, the bush unit 5 (the bush holder 51 incorporating the bush 56) is press-fit into the housing 10. For this reason, before the bush unit 5 is attached to the housing 10, it is possible to check whether there is a gap between the bush 56 and the bush holder 51. Thereby, the vibration resulting from the gap between the bush 56 and the bush holder 51 is suppressed.

  Further, since the bush 56 and the bush holder 51 are separate members, the bush unit 5 can be applied to various racks 11 having different outer diameters. For example, it is possible to use the bush holder 51 as a standard part and to select an appropriate bush 56 from a plurality of types of bushes 56 according to the outer diameter of the rack 11.

  Further, in Patent Document 1 described above, since the stopper is press-fit into the end case, it is necessary to manage the outer diameter of the stopper and the inner diameter of the end case. On the other hand, in the bush unit 5, the number of parts which need to control the radial dimension is reduced. Moreover, in patent document 1, in order to determine the amount of compression of the protrusion part of a bush, it is necessary to manage the dimension of the axial direction of a bush, an end case, and a stopper. On the other hand, in the bush unit 5, there are few parts which need to manage an axial dimension.

  As shown in FIG. 3, the buffer member 15 is attached to the rack 11. The buffer member 15 is located closer to the ball joint 13 than the bush unit 5. The buffer member 15 is made of, for example, rubber. The buffer member 15 is an annular member. As shown in FIG. 3, the outer diameter D <b> 2 of the buffer member 15 is smaller than the inner diameter D <b> 1 of the bush holder 51. Therefore, the buffer member 15 faces the protrusion 513 of the bush holder 51 in the axial direction but does not face the end surface 512 of the bush holder 51. The axial length L2 of the buffer member 15 is larger than the axial distance L1 from the projection 513 of the bush holder 51 to the end surface 512 on the buffer member 15 side.

  As shown in FIG. 3, the rack flange 16 is attached to the rack 11. The rack flange 16 is located closer to the ball joint 13 than the buffer member 15. The rack flange 16 is formed of, for example, metal. The rack flange 16 is an annular member. As shown in FIG. 3, the outer diameter D 3 of the rack flange 16 is larger than the inner diameter D 1 of the bush holder 51. For this reason, the rack flange 16 faces the end surface 512 of the bush holder 51 in the axial direction.

  When the rack 11 moves, the buffer member 15 and the rack flange 16 approach the bush unit 5. Before the rack flange 16 contacts the bush holder 51, the buffer member 15 contacts the projection 513. Then, after the buffer member 15 is deformed, the rack flange 16 contacts the bush holder 51. For this reason, the impact when the rack flange 16 contacts the bush holder 51 is reduced.

  As described above, the bush holder 51 is in contact with the end face 101 of the housing 10. Therefore, when the rack flange 16 contacts the bush holder 51, the rack 11 can not move further with respect to the housing 10. The rack flange 16 and the bush holder 51 determine the distance that the rack 11 can move. The bush holder 51 also serves as a stopper for restricting the movement of the rack 11.

  The steering device 80 may not necessarily include the buffer member 15. However, it is desirable that the steering device 80 be provided with the buffer member 15 in that the shock can be absorbed when the rack 11 is moved vigorously.

  The bush 56 may not have the above-mentioned shape. For example, the bush 56 may not have the convex portion 567. Moreover, before the bush unit 5 is attached to the housing 10, the position of the end surface 511 of the bush holder 51 and the position of the end surface 561 of the bush 56 may not be the same. For example, the end face 561 of the bush 56 may project beyond the end face 511 of the bush holder 51 before the bush unit 5 is attached to the housing 10. The amount of protrusion is, for example, about 0.1 mm. In such a case, when the bush holder 51 is press-fit into the housing 10, the bush 56 is sandwiched between the bush holder 51 and the housing 10, whereby the entire bush 56 is axially compressed.

  The bush holder 51 may not necessarily be manufactured using a standardized pipe material. For example, the bush holder 51 may be manufactured by casting. The material of the bush holder 51 is not particularly limited.

  The steering device 80 may not necessarily include the electric motor 93. That is, the steering device 80 may not be an electric power steering device.

  As described above, the steering device 80 includes the housing 10, the rack 11, the bush holder 51, the bush 56, and the rack flange 16. The rack 11 penetrates the housing 10. The bush holder 51 has a constant outer diameter over the entire axial length of the rack 11 and fits on the inner circumferential surface of the housing 10. The bush 56 is fitted on the inner circumferential surface of the bush holder 51 and contacts the rack 11. The rack flange 16 is attached to the rack 11 and faces the bush holder 51 in the axial direction of the rack 11. The end surface 511 of the bush holder 51 is in contact with the housing 10.

  Since the outer diameter of the bush holder 51 is constant over the entire length in the axial direction, complicated processing on the outer peripheral surface of the bush holder 51 is unnecessary. On the other hand, since the end face 511 of the bush holder 51 is in contact with the housing 10, movement of the rack 11 is restricted when the rack flange 16 is in contact with the bush holder 51. Therefore, even if the outer diameter of the bush holder 51 is constant, the bush holder 51 can also serve as a stopper for restricting the movement of the rack 11. Therefore, the steering device 80 can be easily manufactured and the number of parts can be reduced.

  The steering device 80 also includes a buffer member 15 located between the rack flange 16 and the bush holder 51.

  Thus, the rack flange 16 contacts the bush holder 51 after the buffer member 15 is deformed. For this reason, the impact when the rack flange 16 contacts the bush holder 51 is reduced.

(First modification)
FIG. 7 is an enlarged cross-sectional view of the periphery of the bush unit of the first modified example. In addition, the same code | symbol is attached | subjected to the same component as what was demonstrated in embodiment mentioned above, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 7, the bush 56 </ b> A of the bush unit 5 </ b> A of the first modification includes a protrusion 566 on the end face 561. The protrusion 566 contacts the end face 101 of the housing 10. This facilitates the adjustment of the amount of compression of the bush 56A.

(2nd modification)
FIG. 8 is an enlarged cross-sectional view of one end of a steering gear box according to a second modification. FIG. 9 is a perspective view of a bush unit according to a second modification. FIG. 10 is a perspective view of a bush according to a second modification.

  As shown in FIG. 8, a bush unit 5 </ b> B of the second modification includes a bush holder 51 </ b> B and a bush 58. The bush holder 51B includes a plurality of recesses 515B. The recess 515B is a groove provided on the inner peripheral surface of the bush holder 51B. The recess 515 B is located at the end on the end surface 101 side. The plurality of recesses 515B are arranged at equal intervals in the circumferential direction.

  As shown in FIGS. 8 to 10, the bush 58 includes a plurality of convex portions 587 and a plurality of first slits 588. The convex portion 587 is a protrusion provided on the outer peripheral surface of the bush 58. The plurality of convex portions 587 are arranged at equal intervals in the circumferential direction. The convex portion 587 is fitted in the concave portion 515B of the bush holder 51B. The convex portion 587 is axially compressed by being pinched by the bush holder 51B and the housing 10.

DESCRIPTION OF SYMBOLS 1 steering gear box 10 housing 101 end surface 11 rack 13 ball joint 15 buffer member 16 rack flange 5, 5A, 5B bush unit 51, 51B bush holder 511, 512 end surface 513 protrusion 515, 515B recessed part 56, 56A bush 561, 562 end surface 563 Recess 565 O-ring 566 Protrusion 567 Protrusion 568 1st slit 569 2nd slit 58 Bush 587 Protrusion 580 1st slit 80 Steering device 81 Steering wheel 81 Steering wheel 84 Steering shaft 84 Universal joint 85 Lower shaft 86 Universal joint 87 Pinion shaft 88 Pinion 89 Tie rod 90 ECU
93 electric motor 94 torque sensor 95 vehicle speed sensor 98 ignition switch 99 power supply

Claims (2)

With the housing,
A rack passing through the housing;
A bush holder which has a constant outer diameter over the entire axial length of the rack and which is fitted to the inner circumferential surface of the housing;
A bush fitted to an inner peripheral surface of the bush holder and in contact with the rack;
A rack flange attached to the rack and facing the bush holder in the axial direction;
Equipped with
An end face of the bush holder contacts the housing. The steering apparatus according to claim 1, further comprising a buffer member positioned between the rack flange and the bush holder.

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