JP2019119274A - Steering device - Google Patents

Abstract

To provide a steering device that can inhibit an impact absorption mechanism from increasing in size and endure a large impact load.SOLUTION: The steering device includes a housing 16 and impact absorption mechanisms 50. The housing includes: a rack shaft 12; IBJs 14 connected to opposite ends of the rack shaft 12 to transmit power to a steering wheel; an insertion portion A1; housings A2 arranged at opposite ends of the insertion portion A1 to house the rack shaft 12 when the rack shaft 12 axially reciprocates; and restriction portions A3 each arranged on a border between the insertion portion A1 and the housing A2 and in which an end 14c of each of the IBJs 14 is brought closer thereto or separated therefrom when the rack shaft 12 axially reciprocates. Each of the impact absorption mechanisms is arranged between the restriction portion A3 and the end 14c of the IBJ 14 and is configured to absorb an impact load when the end 14c of the IBJ 14 is brought into contact with the impact absorption mechanism. The impact absorption mechanism 50 is press-fitted to an inner circumferential surface 16d of the housing A2 so as to be separated from the restriction portion A3 by a distance G1.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a steering device.

  Conventionally, there is a steering device that steers the steered wheels by axially reciprocating a steered shaft such as a rack shaft by a steering gear such as a ball screw mechanism or a speed reduction mechanism. The steered wheels are connected to both ends of the rack shaft via ball joints. In the steering apparatus, when the rack shaft moves to the one end side by the maximum amount, a so-called end contact occurs in which the end of the ball joint collides with the housing accommodating the steering gear and the rack shaft. There is known a steering apparatus provided with an impact absorbing mechanism for absorbing an impact load generated at the time of end contact as a device for reducing the impact load at the time of end contact (for example, Patent Document 1).

Unexamined-Japanese-Patent No. 2014-100935

By the way, there is a limit to the impact load which can be endured by the impact absorbing mechanism, and when the limit of the impact load which can be absorbed by the impact absorbing mechanism is increased, there is a concern that the impact absorbing mechanism may be enlarged.
An object of the present invention is to provide a steering device that can withstand a large impact load while suppressing an increase in the size of the impact absorbing mechanism.

  [1] A steering device capable of achieving the above object is connected to a steered shaft that steers a steered wheel by reciprocating in the axial direction, and is connected to both ends of the steered shaft, and transmits power to the steered wheel A cylindrical joint that covers the periphery of the steered shaft, and a housing unit provided at both axial ends of the cylindrical insert in communication with the cylindrical insert, the steered shaft A cylindrical accommodating portion in which the ball joint is accommodated as the axial direction reciprocates, and a restricting portion provided at a boundary between the insertion portion and the accommodating portion, wherein the steering shaft is A housing having a restricting portion in which an end of the ball joint approaches or separates as it reciprocates along the axial direction, and between the restricting portion and the end of the ball joint in the axial direction Provided, said steered shaft The regulating unit or the ends with that reciprocates along the axial direction is assumed to be and a shock absorbing mechanism for absorbing an impact load when in contact. The impact absorbing mechanism is press-fitted to a portion of the inner circumferential surface of the housing portion separated from the restricting portion or a portion of the outer circumferential surface of the steering shaft spaced from the end of the ball joint.

  According to this configuration, when the shock absorbing mechanism is press-fitted to a portion separated from the regulating portion on the inner circumferential surface of the housing portion of the housing, the shock absorbing mechanism is accompanied by the reciprocation of the steered shaft in the axial direction. The end of the ball joint abuts on the mechanism. At this time, the shock absorbing mechanism absorbs the shock load acting on the steering device in a state in which the shock absorbing mechanism is press-fit into the housing portion. Furthermore, when a large impact load, which can not maintain the state in which the shock absorbing mechanism is press-fit fitted to the inner peripheral surface of the housing, acts on the shock absorbing mechanism along the axial direction, the shock absorbing mechanism The impact load is absorbed by sliding between the regulation portions of the housing on the circumferential surface.

  In addition, when the shock absorbing mechanism is press-fit to a portion separated from the end face of the ball joint on the outer peripheral surface of the steered shaft, the housing of the shock absorbing mechanism along with the reciprocation of the steered shaft in the axial direction The restriction part of At this time, an impact load acting on the steering apparatus in a state where the impact absorbing mechanism is press-fit fitted to the turning shaft is absorbed by the impact absorbing mechanism. Furthermore, when a large impact load that can not maintain the state in which the shock absorbing mechanism is press-fit fitted to the outer peripheral surface of the turning shaft acts on the shock absorbing mechanism along the axial direction, the shock absorbing mechanism The impact load is absorbed by sliding between the outer peripheral surface and the end of the ball joint.

  Therefore, in a state in which the shock absorbing mechanism is press-fitted to the inner peripheral surface of the housing portion or the outer peripheral surface of the steered shaft, the shock absorbing mechanism regulates the housing by reciprocating the steered shaft in the axial direction. It has the absorption effect of impact load when the end of the part or the ball joint abuts. In addition, when a large impact load that can not maintain the state in which the impact absorbing mechanism is press-fit fitted to the inner circumferential surface of the housing portion or the outer circumferential surface of the steering shaft acts on the impact absorbing mechanism, the impact is caused by sliding. The impact load can also be absorbed by the frictional force generated between the absorbing mechanism and the inner circumferential surface of the housing or the frictional force generated between the impact absorbing mechanism and the outer circumferential surface of the steering shaft. Therefore, it is possible to withstand a large impact load while suppressing an increase in size of the impact absorbing mechanism.

  [2] In the steering apparatus having the configuration of the above-mentioned [1], a part of the inner peripheral surface of the housing part which is separated from the restricting part, or which is separated from the end of the ball joint in the outer peripheral surface of the steered shaft A fitting groove is provided in the portion, and the impact absorbing mechanism is press-fit fitted in the fitting groove, and is separated from the fitting groove when a load exceeding a predetermined value acts on the impact absorbing mechanism. Preferably, a fitted portion is provided.

  According to this configuration, the shock absorbing mechanism is press-fit fitted in a portion of the inner circumferential surface of the housing portion of the housing separated from the regulating portion of the housing or a portion spaced from the end of the ball joint in the outer circumferential surface of the steering shaft As a result, positional deviation of the shock absorbing mechanism can be suppressed. Further, when an impact load exceeding a predetermined value acts on the impact absorbing mechanism, the fitted portion is separated from the fitting groove, and the fitted portion is against the inner circumferential surface of the housing portion or the outer circumferential surface of the steered shaft. It can slide.

  [3] In the steering apparatus having the configuration of the above-mentioned [2], the shock absorbing mechanism is constituted by an elastic member and is provided with a shock absorbing member for absorbing shock load by being compressed, and the shock absorbing member. It is preferable to have a metal plate, and the to-be-fitted part is integrally provided in the said metal plate.

  According to this configuration, when an impact load exceeding the impact load that can be absorbed by the buffer member acts, the portion sliding against the inner peripheral surface of the housing or the outer peripheral surface of the steering shaft is a metal plate, The frictional force can be more suitably generated when the absorbing mechanism slides.

  [4] In the steering apparatus having the configuration of the above [2] or the configuration of the above [3], the fitting groove is provided over the entire circumferential direction centering on the axis of the steered shaft, The impact absorbing mechanism preferably has an annular shape along the circumferential direction, and the impact absorbing mechanism is preferably provided with a plurality of the fitted portions at intervals in the circumferential direction.

  [5] In the steering apparatus having the configuration of the above-mentioned [4], when the shock absorbing mechanism is viewed from the axial direction, the mating member is directed toward the fitting groove in a radial direction orthogonal to the axial direction. It is preferable that the width along the circumferential direction of the tip end of the portion be small.

  By making the shape of the impact absorbing mechanism into an annular shape, when an impact load exceeding a predetermined value acts on the impact absorbing mechanism, it is possible to more preferably generate a frictional force when the impact absorbing mechanism slides. On the other hand, when the shape of the shock absorbing mechanism is annular, the fitted portion of the shock absorbing mechanism is press-fitted into the fitting groove in the inner peripheral surface of the housing portion of the housing or the fitting groove in the outer peripheral surface of the steering shaft As it is difficult to do so, there is a concern that the assemblability may be reduced.

  In that respect, according to the configuration of the above [5], the number of the fitted parts of the impact absorbing mechanism is changed, or the radial direction along the circumferential direction of the tip of the fitted part as going to the fitting groove side It is possible to change the shape in which the width becomes smaller. Therefore, it is possible to adjust the frictional force when the shock absorbing mechanism slides and the assemblability of the fitted portion of the shock absorbing mechanism by changing the number of fitted portions and the shape of the fitted portion.

  [6] In the steering apparatus having the configuration of any one of the above [1] to [5], a detection unit that detects the movement of the shock absorbing mechanism along the axial direction, and the detection result of the detection unit It is preferable to include a notification operation unit that operates an abnormality notification unit that notifies the driver of an abnormality.

  The movement of the shock absorbing mechanism along the axial direction indicates that the shock load can not be absorbed while maintaining the press-fit fit of the shock absorbing mechanism, that is, a normal non-end-contacting state occurs. That is, it indicates that an abnormality has occurred in the steering device.

  In that respect, according to the configuration of the above [6], when the shock absorbing mechanism moves along the axial direction, the abnormality notifying unit notifies the driver that the shock absorbing mechanism has moved along the axial direction. be able to. As a result, for example, the driver can be urged to take measures, such as checking the vehicle at a dealer.

  According to the steering apparatus of the present invention, it is possible to withstand a large impact load while suppressing an increase in size of the impact absorbing mechanism.

1 schematically shows a first embodiment of a steering device; (A) is sectional drawing of the both ends of the housing in 1st Embodiment, (b) is an expanded sectional view of the metal plate in 1st Embodiment. FIG. 5 is a front view of the shock absorbing mechanism of the first embodiment as viewed in the axial direction from the stepped surface side of the housing. (A) is sectional drawing of the both ends of the housing in 2nd Embodiment of a steering device, (b) is an expanded sectional view of the metal plate in 2nd Embodiment. The front view when the impact absorption mechanism of 2nd Embodiment is seen from the end side of a housing along an axial direction. Sectional drawing of the both ends of the housing in other embodiment of a steering device.

First Embodiment
Hereinafter, an embodiment of a steering device will be concretely described as an electric power steering device 1 (hereinafter referred to as “EPS device 1”).

  As shown in FIG. 1, the EPS device 1 includes a steering mechanism 2 for turning the steered wheels 15 based on the driver's operation of the steering wheel 10, and an assist mechanism 3 for assisting the driver's operation of the steering wheel 10. A housing 16 accommodates a portion of the steering mechanism 2 and a portion of the assist mechanism 3, and a control unit 90 that controls the operation of the motor 20 of the assist mechanism 3.

  The steering mechanism 2 includes a steering wheel 10, a steering shaft 11 that rotates integrally with the steering wheel 10, and a rack shaft 12 as a steered shaft that reciprocates in the axial direction in conjunction with the steering shaft 11. The outer peripheral surface 12c of the rack shaft 12 is provided with a screw groove 12a (left side in FIG. 1) and rack teeth 12b (right side in FIG. 1).

  In the following description, “axial direction” means a direction along the axis m of the rack shaft 12, “radial direction” means a direction orthogonal to the “axial direction”, and “circumferential direction” The direction around the axis m of the rack shaft 12 is shown.

  The steering shaft 11 has a column shaft 11a connected to the steering wheel 10, an intermediate shaft 11b connected to the lower end of the column shaft 11a, and a pinion shaft 11c connected to the lower end of the intermediate shaft 11b. There is. The lower end portion of the pinion shaft 11c is provided with pinion teeth 11d.

  A rack and pinion mechanism 13 is configured by the pinion teeth 11 d of the pinion shaft 11 c and the rack teeth 12 b of the rack shaft 12 meshing with the pinion teeth 11 d. Therefore, the rotational movement of the steering shaft 11 is converted to reciprocating movement in the axial direction (left and right direction in FIG. 1) of the rack shaft 12 through the rack and pinion mechanism 13. The rotational movement (power) of the rack shaft 12 is transmitted to the left and right steered wheels 15 via inner ball joints 14 (hereinafter referred to as "IBJ 14") connected to both ends of the rack shaft 12, respectively. The turning angle of the steering wheel 15 is changed.

  As shown in FIG. 2, the IBJ 14 has a tie rod 14a and a socket portion 14b. A ball portion 14d is provided at the tip of the tie rod 14a. The ball portion 14d is rotatably and bendably accommodated in the socket portion 14b. The tie rods 14a are attached at an angle to the axis m of the rack shaft 12.

  As shown in FIG. 1, the assist mechanism 3 includes a motor 20 which is a generation source of assist force, a ball screw mechanism 30 attached to the rack shaft 12 and supporting the rack shaft 12 so as to reciprocate, and rotation of the motor 20. A belt type reduction mechanism 40 for transmitting the rotational force of the shaft 21 to the ball screw mechanism 30 is provided. The assist mechanism 3 converts the rotational force of the rotation shaft 21 of the motor 20 into an axial force that causes the rack shaft 12 to reciprocate in the axial direction via the speed reduction mechanism 40 and the ball screw mechanism 30. The axial force along the axis m applied to the rack shaft 12 is an assist force, and the driver's operation of the steering wheel 10 is assisted.

  The motor 20 has a rotation angle sensor 20a. The control unit 90 controls power supply to the motor 20 based on the rotation angle θ of the motor 20 detected by the rotation angle sensor 20 a and signals from a steering angle sensor, a torque sensor, etc. (not shown). Further, the control unit 90 determines whether or not an abnormality occurs in the EPS device 1 based on the rotation angle θ. The control unit 90 is connected to the abnormality notification unit 95 mounted on the vehicle. When it is determined that an abnormality has occurred in the EPS device 1, the control unit 90 operates the abnormality notification unit 95. The abnormality notification unit 95 is, for example, a warning light mounted on an instrument panel inside the vehicle.

  The rack shaft 12, the ball screw mechanism 30, the reduction gear mechanism 40, and a portion of the pinion shaft 11 c are accommodated in the housing 16. The housing 16 is configured by connecting the axially divided first housing 16a and the second housing 16b. The first housing 16a communicates with the first housing portion S1 for housing the assist mechanism 3 and the first housing portion S1, and extends to the opposite side (left side in FIG. 1) of the rack and pinion mechanism 13. And a cylindrical portion S3. The second housing 16b communicates with the second housing portion S2 for housing the assist mechanism 3 and the second housing portion S2, and extends to the rack and pinion mechanism 13 side (right side in FIG. 1). And S4.

  The rack shaft 12 is configured such that the first housing portion S1, the first cylindrical portion S3, the second housing portion S2, and the second housing portion S2 with the first housing 16a and the second housing 16b connected to each other. It is accommodated in the inside of cylindrical part S4. Here, a cylindrical insertion portion A1 having an insertion hole 16c through which the rack shaft 12 is inserted is configured by the first cylindrical portion S3 and the second cylindrical portion S4.

  A through hole 22 is provided in the outer wall (right side wall in the drawing) of the second housing portion S2 of the second housing 16b. The rotation shaft 21 of the motor 20 is accommodated inside the second housing 16 b through the through hole 22. The motor 20 is fixed to the second housing 16 b by a bolt 23. The rotation axis 21 is parallel to the rack shaft 12.

Next, the structure of both ends of the housing 16 will be described in detail.
As shown in FIG. 2, the housing 16 is provided with a cylindrical housing portion A <b> 2, a restricting portion A <b> 3 and an insertion portion A <b> 1 in order from the end thereof.

  The housing portions A2 are provided at both end portions in the axial direction of the insertion portion A1. The housing portion A2 and the insertion portion A1 are provided coaxially. The inner circumferential surface 16d of the housing portion A2 and the insertion hole 16c of the insertion portion A1 communicate with each other. The accommodation portion A2 accommodates the IBJ 14 as the rack shaft 12 reciprocates in the axial direction. For this reason, the inner diameter D1 of the inner peripheral surface 16d of the housing portion A2 is larger than the outer diameter of the socket portion 14b of the IBJ 14. Further, the inner diameter D1 of the inner peripheral surface 16d of the housing portion A2 is larger than the inner diameter of the insertion hole 16c of the insertion portion A1. An annular step surface 16e is provided at a restriction portion A3 which is an axial boundary between the inner circumferential surface 16d of the housing portion A2 and the insertion hole 16c of the insertion portion A1. The IBJ 14 approaches or separates from the step surface 16 e as the rack shaft 12 reciprocates in the axial direction. A fitting groove 16f is provided on the inner circumferential surface 16d of the housing portion A2. The fitting groove 16f is provided along the entire circumferential direction around the axis m at a position separated from the step surface 16e by a predetermined distance G1 in the axial direction.

  In the housing 16, an impact absorbing mechanism 50 is provided between the step surface 16e and the end 14c of the IBJ 14 axially opposed to the step surface 16e. The shock absorbing mechanism 50 has an annular shape. The rack shaft 12 is inserted into the impact absorbing mechanism 50. The impact absorbing mechanism 50 is provided at a portion where the fitting groove 16f is provided in the inner peripheral surface 16d of the housing portion A2, that is, at a portion spaced apart from the step surface 16e in the axial direction by a predetermined distance G1.

  Reciprocation along the axial direction of the rack shaft 12 is limited by the end rest caused by the end 14 c of the IBJ 14 axially impinging on the shock absorbing mechanism 50. That is, the stroke end (movement limit) when the rack shaft 12 is moved to the one end side in the axial direction by the maximum amount is defined by the end 14 c of the IBJ 14 striking the shock absorbing mechanism 50 in the axial direction. .

  In addition, when the end 14 c of the IBJ 14 abuts on the impact absorbing mechanism 50, an impact load acts on the impact absorbing mechanism 50 along the axial direction. That is, the impact absorbing mechanism 50 is set so as to be capable of absorbing an impact load which is equal to or less than a predetermined value F caused by reciprocating movement of the rack shaft 12 in the axial direction.

Next, the configuration of the shock absorbing mechanism 50 will be described.
As shown in FIGS. 2 (a), (b) and FIG. 3, in the shock absorbing mechanism 50, an annular metal plate 51, a cylindrical buffer member 52, and a cylindrical end plate 53 are integrally formed. It is configured by being assembled.

  The metal plate 51 has an annular disc portion 51a and a fitted portion 51b. The fitted portion 51b is integrally provided on the outer peripheral side of the disc portion 51a. The fitted portion 51b protrudes outward in the radial direction from the outer peripheral surface of the disc portion 51a. The fitted portion 51 b is press-fitted into the fitting groove 16 f in the housing portion A 2 of the housing 16. In a state in which the fitted portion 51b is press-fitted into the fitting groove 16f, the distance from the step surface 16e of the housing 16 to the end face of the disc portion 51a on the step surface 16e side is a distance G1. Here, a depth T1 in the radial direction of the fitting groove 16f and a height H1 of the fitted portion 51b from the outer peripheral surface of the disc portion 51a are such that an impact load exceeding a predetermined value F acts on the impact absorbing mechanism 50. In this case, the fitted portion 51b is set to be separated from the fitting groove 16f. The predetermined value F is a value of an impact load that can be absorbed by the buffer member 52 in a state in which the impact absorbing mechanism 50 is press-fitted to the inner peripheral surface 16 d of the housing portion A2.

  As shown in FIG. 3, a plurality of fitted portions 51 b are provided on the outer peripheral surface of the disc portion 51 a at equal intervals in the circumferential direction. When the shock absorbing mechanism 50 is viewed along the axial direction, the fitted portion 51 b has a semicircular shape in which the width along the circumferential direction decreases toward the outer side in the radial direction. The inner diameter D2 of the virtual circle passing through the tip of the fitted portion 51b is larger than the inner diameter D1 of the inner peripheral surface 16d of the housing portion A2 of the housing 16.

  As shown to Fig.2 (a), the buffer member 52 is comprised by the elastic member. An example of the elastic member is rubber, synthetic resin, or the like. The buffer member 52 has an annular shape. The buffer member 52 absorbs an impact by being axially compressed when the end 14 c of the IBJ 14 axially collides with the impact absorbing mechanism 50 as the rack shaft 12 axially reciprocates.

  As shown in FIGS. 2A and 3, a cylindrical portion 52 b extending in the axial direction toward the step surface 16 e of the housing 16 is provided on the end surface 52 a of the buffer member 52 on the step surface 16 e side of the housing 16. It is done. The cylindrical portion 52 b is provided on the inner peripheral side of the end surface 52 a of the buffer member 52. The end surface 52a of the buffer member 52 is in contact with the end surface of the disc portion 51a opposite to the stepped surface 16e. The cylindrical portion 52b is fitted in a hole 51c provided in the disc portion 51a.

The end plate 53 is made of a metal member. The end plate 53 has an annular first plate 53a and a cylindrical second plate 53b.
One end face in the thickness direction of the first plate 53 a is in contact with an end face 52 c on the end 14 c side of the IBJ 14 in the buffer member 52. The outer diameter of the first plate 53 a is smaller than the inner diameter D 1 of the inner peripheral surface 16 d of the housing portion A 2 of the housing 16.

  The second plate 53 b extends in the axial direction from the inner edge side of the first plate 53 a toward the step surface 16 e of the housing 16. The outer peripheral surface of the second plate 53 b is in contact with the inner peripheral surface of the buffer member 52. The inner diameter of the inner peripheral surface of the second plate 53 b is larger than the outer diameter D 3 of the outer peripheral surface 12 c of the rack shaft 12.

Next, the operation of the shock absorbing mechanism 50 will be described.
When the vehicle on which the EPS device 1 is mounted is traveling, it is conceivable that the steered wheels 15 of the vehicle ride on uneven portions such as curbs on the road surface. When the steered wheels 15 ride on the uneven portion, an axial force acts on the rack shaft 12 via the IBJ 14. As a result, it is conceivable that the rack shaft 12 moves the maximum amount to one end side in the axial direction and reaches the stroke end. When the stroke end is reached, the end 14 c of the IBJ 14 abuts on the first plate 53 a of the end plate 53 of the shock absorbing mechanism 50. The impact load acting at this time acts on the buffer member 52 through the first plate 53a. In this case, the buffer member 52 absorbs an impact load by being compressed in the axial direction between the first plate 53 a of the end plate 53 and the disc portion 51 a of the metal plate 51.

  However, there is an upper limit to the impact load absorption effect due to compression of the buffer member 52. When the shock load acting on the shock absorption mechanism 50 exceeds the shock load which can be absorbed by the shock absorbing member 52 in a state where the shock absorption mechanism 50 is press-fit fitted to the inner circumferential surface 16 d of the housing portion A2, the shock load 52 It can be considered that it can not absorb

  In that respect, in the present embodiment, when an impact load exceeding the predetermined value F acts on the impact absorbing mechanism 50, the fitted portion 51b of the metal plate 51 of the impact absorbing mechanism 50 is disengaged from the fitting groove 16f of the housing 16. Is configured as.

  When an impact load exceeding the predetermined value F acts on the impact absorbing mechanism 50, the fitted portion 51b of the metal plate 51 is separated from the fitting groove 16f, and then the distance G1 on the inner peripheral surface 16d of the housing portion A2 of the housing 16 Ride on the part that corresponds to Furthermore, after the rack shaft 12 reaches the stroke end, the rack shaft 12 tends to move in the axial direction toward the step surface 16e. Therefore, the metal plate 51 of the shock absorbing mechanism 50 moves toward the step surface 16 e of the housing 16 together with the IBJ 14. With the movement of the metal plate 51 toward the step surface 16 e of the housing 16, the tip end of the fitted portion 51 b of the metal plate 51 slides on the inner circumferential surface 16 d of the housing portion A 2 of the housing 16. In the case where the distance G1 can not maintain the state in which the shock absorbing mechanism 50 is press-fitted to the inner circumferential surface 16d of the housing portion A2, the fitted portion 51b extends over the inner circumferential surface 16d of the housing portion A2. It is set so that the impact load can be sufficiently absorbed by the frictional force generated by the sliding.

Next, abnormality determination in the control unit 90 will be described.
Once the fitted portion 51 b of the shock absorbing mechanism 50 separates from the fitting groove 16 f of the housing 16 and moves toward the step surface 16 e of the housing 16, the shock absorbing mechanism 50 again performs the step surface 16 e of the housing 16. , And can not return to a site separated by a distance G1. That is, the stroke amount of the EPS device 1 changes. Therefore, the fact that the shock absorbing mechanism 50 moves along the axial direction and the stroke amount changes is a state where the shock load can not be absorbed while maintaining the press-fit fit of the shock absorbing mechanism 50, that is, a normal end contact It shows that the condition which is not occurred has occurred, and it has shown that abnormality has occurred in the EPS device 1. The control unit 90 determines the abnormality of the EPS device 1 based on the movement of the shock absorbing mechanism 50 along the axial direction.

  As shown in FIG. 1, the control unit 90 has a non-volatile memory 91 and a notification operation unit 92. The memory 91 of the control unit 90 stores a threshold θth of the rotation angle θ detected by the rotation angle sensor 20a. Here, the threshold θth of the rotation angle θ is a stroke due to the rack shaft 12 reciprocating along the axial direction in a state in which the impact absorbing mechanism 50 is press-fit fitted to the inner circumferential surface 16 d of the housing portion A2. It is the value when reaching the end. The notification operation unit 92 has a function of operating the abnormality notification unit 95 when the control unit 90 determines that the EPS device 1 is abnormal.

  When an impact load exceeding a predetermined value F is applied to the impact absorbing mechanism 50, the impact absorbing mechanism 50 moves toward the step surface 16e of the housing 16, so that the rack shaft 12 also moves along the axial direction beyond the stroke end. . Therefore, along with the movement of the rack shaft 12 in the axial direction, the rotation shaft 21 of the motor 20 is also rotated via the ball screw mechanism 30 and the reduction mechanism 40. That is, when an impact load exceeding the predetermined value F acts on the impact absorbing mechanism 50, the rotation angle θ detected by the rotation angle sensor 20a of the motor 20 exceeds the threshold θth.

  Therefore, when the rotation angle θ detected by the rotation angle sensor 20a exceeds the threshold value θth, the control unit 90 detects that the press-fit fit of the impact absorbing mechanism 50 is released. When the rotation angle θ exceeds the threshold θth, the control unit 90 determines that the EPS device 1 is abnormal. The notification operation unit 92 operates the abnormality notification unit 95 when the control unit 90 determines that the EPS device 1 is abnormal. The control unit 90 and the rotation angle sensor 20a constitute a detection unit.

The effects of this embodiment will be described.
(1) In a state where the shock absorbing mechanism 50 is press-fit fitted to the inner circumferential surface 16d of the housing portion A2, the shock absorbing mechanism 50 causes the end 14c of the IBJ 14 to reciprocate in the axial direction of the rack shaft 12 Has an effect of absorbing impact load when it contacts. In addition, when a large impact load that can not maintain the state in which the impact absorbing mechanism 50 is press-fit fitted to the inner circumferential surface 16 d of the housing portion A2 acts on the impact absorbing mechanism 50, the impact absorbing mechanism 50 is slid. The impact load can also be absorbed by the frictional force generated between the and the inner peripheral surface 16d of the housing portion A2. Therefore, it is possible to withstand a large impact load while suppressing an increase in size of the impact absorbing mechanism 50.

  (2) The fitted portion 51 b of the impact absorbing mechanism 50 is press-fitted into the fitting groove 16 f of the housing 16. Therefore, positional deviation of the shock absorbing mechanism 50 can be suppressed. Further, when an impact load exceeding the predetermined value F acts on the impact absorbing mechanism 50, the fitted portion 51b separates from the fitting groove 16f, and the fitted portion 51b against the inner circumferential surface 16d of the housing portion A2. It can slide.

  (3) When an impact load exceeding the impact load that can be absorbed by the buffer member 52 acts, the portion sliding against the inner peripheral surface 16 d of the housing portion A2 is the metal plate 51, so the impact absorbing mechanism 50 slides The friction force can be more suitably generated during the process.

  (4) When the shock absorbing mechanism 50 has an annular shape, when an impact load exceeding the predetermined value F acts on the shock absorbing mechanism 50, the inner peripheral surface 16d of the shock absorbing mechanism 50 and the housing portion A2 of the housing 16 And the friction force generated between them can be generated more suitably. On the other hand, when the shock absorbing mechanism 50 has an annular shape, the fitted portion 51b of the shock absorbing mechanism 50 is difficult to press fit into the fitting groove 16f in the inner peripheral surface 16d of the housing portion A2 of the housing 16. There is a concern that the assemblability may be reduced.

  In that respect, the number of the fitted portions 51b of the shock absorbing mechanism 50 may be changed, or the width along the circumferential direction of the tip of the fitted portion 51b may be reduced toward the fitting groove 16f in the radial direction. Can be changed. Therefore, the frictional force when the shock absorbing mechanism 50 slides and the assemblability of the fitted portion 51b of the shock absorbing mechanism 50 are adjusted by changing the number of fitted portions 51b and the shape of the fitted portion 51b. be able to.

  (5) When the shock absorbing mechanism 50 moves in the axial direction, the abnormality notifying unit 95 can notify the driver that the shock absorbing mechanism 50 is displaced in the axial direction. As a result, for example, the driver can be urged to take measures, such as checking the vehicle at a dealer.

Second Embodiment
Hereinafter, a second embodiment of the steering device will be described. The same components as those of the first embodiment will be described with the same reference numerals. The basic configuration of the present embodiment is the same as that of the first embodiment, and the main difference from the first embodiment is that the portion to which the shock absorbing mechanism is press-fitted is the rack shaft 12. It is a point which is the outer peripheral surface 12c.

  As shown in FIG. 4A, the reciprocation along the axial direction of the rack shaft 12 is limited by the end rest caused by the impact absorbing mechanism 60 striking the stepped surface 16 e of the housing 16. That is, the stroke end when the rack shaft 12 is moved to the one end side in the axial direction by the maximum amount is defined by the impact absorbing mechanism 60 striking the stepped surface 16 e of the housing 16 in the axial direction.

  A fitting groove 12 d is provided on the outer peripheral surface 12 c of the rack shaft 12. The fitting groove 12d is provided on the entire circumference in the circumferential direction around the axis m at a position separated from the end 14c of the IBJ 14 by a predetermined distance G2 in the axial direction.

  As shown in FIGS. 4A, 4B and 5, in the shock absorbing mechanism 60, an annular metal plate 61, a cylindrical buffer member 62, and a cylindrical end plate 63 are integrally formed. It is configured by being assembled.

  The metal plate 61 has an annular disc portion 61 a and a fitted portion 61 b. The fitted portion 61b is integrally provided on the inner peripheral side of the disc portion 61a. The fitted portion 61b protrudes inward in the radial direction from the inner peripheral surface of the disc portion 61a. The fitted portion 61 b is press-fitted into the fitting groove 12 d in the outer peripheral surface 12 c of the rack shaft 12. In a state where the fitted portion 61b is press-fit into the fitting groove 12d, the distance from the end 14c of the IBJ 14 to the end 14c of the IBJ 14 of the disc portion 61a is a distance G2. Here, the depth T2 in the radial direction of the fitting groove 12d and the height H2 of the fitted portion 51b from the outer peripheral surface of the disc portion 51a are affected by an impact load exceeding the predetermined value F on the impact absorbing mechanism 60. In this case, the fitted portion 61b is set to be separated from the fitting groove 12d. The predetermined value F is a value of an impact load that can be absorbed by the buffer member 62 in a state where the impact absorbing mechanism 60 is press-fit fitted to the outer peripheral surface 12 c of the rack shaft 12.

  As shown in FIG. 5, a plurality of fitted portions 61 b are provided on the inner circumferential surface of the disc portion 61 a at equal intervals in the circumferential direction. When the impact absorbing mechanism 60 is viewed along the axial direction, the fitted portion 61 b has a semicircular shape in which the width along the circumferential direction decreases in the radial inward direction. The inner diameter D4 of the virtual circle passing through the tip of the fitted portion 61b is smaller than the outer diameter D3 of the outer peripheral surface 12c of the rack shaft 12.

  As shown in FIG. 4A, the buffer member 62 has substantially the same configuration as the buffer member 52. The buffer member 62 absorbs an impact by being compressed in the axial direction when the step surface 16 e of the housing 16 axially collides with the impact absorbing mechanism 60 as the rack shaft 12 reciprocates in the axial direction.

  As shown in FIGS. 4A and 5, the end face 62 a of the buffer member 62 on the end side of the housing 16 is provided with a cylindrical portion 62 b extending in the axial direction toward the end of the housing 16. There is. The cylindrical portion 62 b is provided on the outer peripheral side of the end surface 62 a of the buffer member 62. The end face 62a of the buffer member 62 is in contact with the end face of the disc portion 61a on the side of the step surface 16e. The disc portion 61a is fitted to the inner peripheral surface of the cylindrical portion 62b.

The end plate 63 is made of a metal member. The end plate 63 has an annular first plate 63a and a cylindrical second plate 63b.
One end face in the thickness direction of the first plate 63 a is in contact with an end face 62 c on the step surface 16 e side of the housing 16 in the buffer member 62. The inner diameter of the first plate 63 a is larger than the outer diameter D 3 of the outer circumferential surface 12 c of the rack shaft 12.

  The second plate 63 b extends in the axial direction from the outer edge side of the first plate 63 a toward the end of the housing 16. The inner peripheral surface of the second plate 63 b is in contact with the outer peripheral surface of the buffer member 62. The outer diameter of the outer peripheral surface of the second plate 63 b is smaller than the inner diameter D 1 of the inner peripheral surface 16 d of the housing portion A 2 of the housing 16.

Also in the present embodiment, the control unit 90 (see FIG. 1) is provided, and the same control as in the first embodiment is performed.
The main difference between this embodiment and the first embodiment is that when a large impact load, which can not be maintained by press-fitting of the impact absorbing mechanism 60, acts on the impact absorbing mechanism 60, The portion 61 b slides on the outer peripheral surface 12 c of the rack shaft 12, and the effect is basically the same as that of the first embodiment.

  The first and second embodiments can be modified as follows. The first and second embodiments and the following modifications can be combined with one another as long as there is no technical contradiction.

  In the first and second embodiments, the control unit 90 detects the movement of the impact absorbing mechanisms 50 and 60 in the axial direction based on the rotation angle θ detected by the rotation angle sensor 20a. Not exclusively. For example, the axial movement of the impact absorbing mechanisms 50 and 60 may be detected based on the steering angle of the steering wheel 10 detected by the steering angle sensor. At this time, the threshold value of the steering angle at the stroke end time is stored in the memory 91 of the control unit 90. When the steering angle detected by the steering angle sensor exceeds the threshold value, the control unit 90 may detect that the shock absorbing mechanisms 50 and 60 have moved in the axial direction. At this time, the steering angle sensor and the control unit 90 constitute a detection unit. Further, the configuration is not limited to the steering angle detected by the steering angle sensor, and any configuration may be employed as long as it can detect that the rack shaft 12 moves beyond the stroke end.

  In the first and second embodiments, the fitted parts 51b and 61b of the impact absorbing mechanisms 50 and 60 may be, for example, shafts if the fitted parts can be press-fitted into the fitting grooves 12d and 16f. The shape of the fitted portion 51b when the impact absorbing mechanism 50 is viewed from the direction is not limited to a semicircular shape, and for example, a triangular shape, a trapezoidal shape, and a rectangular protrusion whose width does not change along the radial direction It may be changed to

  -In 1st, 2nd embodiment, although fitting groove 12d, 16f was provided over the perimeter of the circumferential direction, it does not restrict to this. For example, the fitting grooves may be provided only in the portions corresponding to the fitted portions 51 b and 61 b of the impact absorbing mechanisms 50 and 60. Moreover, as long as the to-be-fitted part 51b is provided with two or more at intervals in the circumferential direction, it may not be at equal intervals. For example, the fitted portions 51b and 61b may be provided over the entire circumference in the circumferential direction. Even in this case, it suffices to be able to press fit into the fitting grooves 12d and 16f. Further, the height may be set to such an extent that it can be separated from the fitting grooves 12d and 16f when an impact load exceeding the predetermined value F acts on the impact absorbing mechanisms 50 and 60.

  In the first and second embodiments, the impact absorbing mechanisms 50 and 60 may not be annular. That is, the metal plates 51 and 61, the buffer members 52 and 62, and a part of the end plates 53 and 63 may be cut away to form a C shape.

  In the first and second embodiments, the impact load is absorbed by axially compressing the buffer members 52 and 62 of the impact absorbing mechanisms 50 and 60. However, the first plate of the end plates 53 and 63 is used. An impact load absorbing effect by deforming 53a and 63a may also be added. For example, the rigidity of the end plates 53 and 63 is set to a degree that can be deformed by impact load. Also, the end plates 53, 63 may be omitted.

  -In 1st, 2nd embodiment, although to-be-fitted part 51b, 61b was provided in the metal plates 51 and 61, it does not restrict to this. For example, the metal plates 51 and 61 are also omitted together with the end plates 53 and 63, and a flange portion is provided on the outer peripheral surface of the buffer member 52 or the inner peripheral surface of the buffer member 62 to fit in the fitting grooves 12d and 16f. May be That is, the shock absorbing mechanisms 50 and 60 may be configured only by the buffer members 52 and 62.

  In the first and second embodiments, the impact absorbing mechanisms 50 and 60 may be configured of only the metal plates 51 and 61. In this case, the thickness and the like in the axial direction of the metal plates 51 and 61 are changed so as to absorb an impact load which is equal to or less than the predetermined value F.

  In the first and second embodiments, the impact absorbing mechanism 50 is accommodated in the housing portion A2 of the housing 16 by fitting the fitted portions 51b and 61b of the impact absorbing mechanisms 50 and 60 into the fitting grooves 12d and 16f. The impact absorbing mechanism 60 is press fitted to the outer circumferential surface 12 c of the rack shaft 12 on the inner circumferential surface 16 d of the above, but the present invention is not limited to this. For example, as shown in FIG. 6, the outer peripheral surface of the buffer member 72 may be press-fit fitted in close contact with the inner peripheral surface 16 d of the housing portion A 2 of the housing 16.

  In the first and second embodiments, the EPS device 1 is embodied such that the rotation shaft 21 of the motor 20 and the rack shaft 12 are parallel to each other, but the present invention is not limited thereto. For example, the present invention may be applied to an EPS device in which the rotary shaft 21 and the rack shaft 12 exist coaxially, or another EPS device such as a manual steering device. Further, although the steering apparatus is embodied in the EPS apparatus 1, it may be applied to, for example, a steer-by-wire steering apparatus.

DESCRIPTION OF SYMBOLS 1 ... Electric-power-steering apparatus (EPS apparatus), 12 ... Rack shaft, 12c ... Outer peripheral surface, 12d, 16f ... Fitting groove, 14 ... Inner ball joint (IBJ), 14c ... End part, 15 ... Turning wheel, 16 ... Housing, 16d: inner circumferential surface, 16e: step surface, 20: motor, 20a: rotation angle sensor, 50, 60: impact absorbing mechanism, 51, 61: metal plate, 51b, 61b: fitted portion, 52, 62 , 72: buffer member, 90: control unit, 92: notification operation unit, 95: abnormality notification unit, A1: insertion unit, A2: accommodation unit, A3: restriction unit, F: predetermined value.

Claims (6)

A steered shaft that steers the steered wheels by reciprocating in the axial direction;
A ball joint connected to both ends of the steered shaft for transmitting power to the steered wheels;
A cylindrical insertion portion covering the periphery of the steering shaft, and a storage portion provided at both ends in the axial direction of the insertion portion in communication with the insertion portion, the steering shaft being in the axial direction A cylindrical accommodating portion in which the ball joint is accommodated along with reciprocating movement, and a restricting portion provided at a boundary between the insertion portion and the accommodating portion, wherein the steering shaft is along the axial direction A housing having a restriction portion in which an end of the ball joint approaches or separates as it moves back and forth;
It is provided between the restricting portion and the end of the ball joint in the axial direction, and when the restricting portion or the end abuts as the steered shaft reciprocates along the axial direction. A shock absorbing mechanism that absorbs the shock load of the
The impact absorbing mechanism is press-fitted to a portion of the inner circumferential surface of the housing portion separated from the regulating portion or a portion of the outer circumferential surface of the steered shaft spaced from the end of the ball joint. apparatus. A fitting groove is provided in a portion of the inner circumferential surface of the housing portion separated from the restricting portion or in a portion of the outer circumferential surface of the steered shaft separated from the end of the ball joint,
The impact absorbing mechanism is provided with a fitted portion which is press-fit and fitted in the fitting groove and which is disengaged from the fitting groove when a load exceeding a predetermined value acts on the impact absorbing mechanism. The steering apparatus according to 1. The shock absorbing mechanism includes a shock absorbing member configured to be shocked by being constituted by an elastic member and compressed, and a metal plate to which the shock absorbing member is attached.
The steering apparatus according to claim 2, wherein a fitting portion is integrally provided on the metal plate. The fitting groove is provided over the entire circumference in the circumferential direction centering on the axis of the turning shaft,
The shock absorbing mechanism has an annular shape along the circumferential direction,
The steering apparatus according to claim 2 or 3, wherein the impact absorbing mechanism is provided with a plurality of the fitted portions at intervals in the circumferential direction. When the impact absorbing mechanism is viewed from the axial direction, the width along the circumferential direction of the distal end portion of the fitted portion becomes smaller toward the fitting groove side in the radial direction orthogonal to the axial direction The steering apparatus according to claim 4. A detection unit that detects movement of the shock absorbing mechanism along the axial direction;
The steering apparatus according to any one of claims 1 to 5, further comprising: a notification operation unit that operates an abnormality notification unit that notifies an abnormality to a driver based on a detection result of the detection unit.