Steering device

Abstract

A steering device (10) comprises a steering shaft (14) that can be operated in a state in which power transmission from steered wheels of a vehicle is blocked. The steering device comprises: an interlocking rotating body (82) that rotates around the axis of the steering shaft in conjunction with the rotation of the steering shaft; and a rotation-stopping part (62) that stops the interlocking rotating body by coming into contact with the interlocking rotating body. A groove and an elastic member attached to the groove are provided to at least one of a facing part of the interlocking rotating body and a facing part of the rotation-stopping part that face each other when the interlocking rotating body and the rotation stopping part come into contact with each other. The facing part of the interlocking rotating body and the facing part of the rotation-stopping part have abutting surfaces configured so as to be able to come into contact with each other by deformation of the elastic member.

Description

Steering gear

[0001] The present disclosure relates to a steering device.

[0002] Japanese Patent Application Laid-Open Publication No. 2006-109494 (Patent Document 1) describes a device for mechanically limiting the rotational range of a steering shaft in a steer-by-wire system. Specifically, the device includes a first rotating member that rotates in conjunction with the steering shaft and a second rotating member that rotates with the first rotating member. The device also includes a restricting member that contacts the second rotating member to prevent rotation of the second rotating member when the second rotating member reaches a predetermined rotation angle. When the first rotating member rotates a predetermined amount from the steering angle at which rotation of the second rotating member is prevented by the restricting member, the first rotating member and the second rotating member come into contact with each other, preventing rotation of the first rotating member. This prevents rotation of the first rotating member.

[0003] Furthermore, the same document 1 describes that the contact surfaces of the first rotating member and the second rotating member are covered with an elastic member (paragraph "0076").

[0004] Japanese Patent Application Laid-Open No. 2020-69844

[0005] However, when the contact surface is covered with an elastic member as described above, the steering angle is likely to fluctuate when the rotation of the steering shaft is restricted, which reduces the accuracy of detecting the upper limit of the rotation angle of the steering shaft.

[0006] One aspect of the present disclosure provides a steering device. The steering device includes a steering shaft that can be operated while power transmission from the steered wheels of a vehicle is cut off. The steering device includes an interlocking rotor that rotates around the axis of the steering shaft in conjunction with the rotation of the steering shaft, and a rotation stopping portion that stops the interlocking rotor by contacting the interlocking rotor. The interlocking rotor has an opposing portion that faces the rotation stopping portion when it comes into contact with the rotation stopping portion. The rotation stopping portion has an opposing portion that faces the interlocking rotor when it comes into contact with the interlocking rotor. At least one of the opposing portion of the interlocking rotor and the opposing portion of the rotation stopping portion is provided with a groove and an elastic member attached to the groove. The opposing portion of the interlocking rotor and the opposing portion of the rotation stopping portion have abutment surfaces that are configured to be able to come into contact with each other when the elastic member is deformed.

[0007] FIG. 6A is a diagram showing the configuration of a steering system according to a first embodiment. FIG. 6B is an exploded perspective view showing the configuration of a portion of the reaction force actuator shown in FIG. 1. FIG. 6C is an exploded perspective view showing the configuration of a portion of the reaction force actuator shown in FIG. 2. FIG. 6D is a cross-sectional view showing the configuration of a portion of the reaction force actuator shown in FIG. 2. FIG. 6E is a diagram showing the operation of the stopper function of the reaction force actuator shown in FIG. 6A. FIG. 6F is a cross-sectional view taken along line 6-6 in FIG. 6F. FIG. 6G is a cross-sectional view of a comparative example to the configuration of FIG. 6A. A cross-sectional view of an end stopper, etc. FIG. 6H is an exploded perspective view showing the configuration of a portion of the reaction force actuator according to a second embodiment.

[0008] First Embodiment A first embodiment will be described below with reference to the drawings. "Prerequisite Configuration" A vehicle steering device 10 shown in FIG. 1 is a steer-by-wire device. The steering device 10 includes a steering wheel 12, a steering shaft 14, a reaction force actuator 20, and a turning actuator 30. The steering shaft 14 is connected to the steering wheel 12. The reaction force actuator 20 is used to apply a force that resists the force exerted by the driver when operating the steering wheel 12. The reaction force actuator 20 includes a reaction force motor 22, a reaction force inverter 24, and a reaction force reduction mechanism 26. The reaction force motor 22 applies a steering reaction force, which is a force that resists steering, to the steering wheel 12 via the steering shaft 14. The reaction force motor 22 is connected to the steering shaft 14 via the reaction force reduction mechanism 26. The reaction force reduction mechanism 26 is, for example, a worm and wheel.

[0009] The steering actuator 30 is used to steer the steerable wheels 34 in accordance with the driver's steering intention, which is indicated by the driver's operation of the steering wheel 12. The steering actuator 30 includes a rack shaft 32, a steering motor 42, a steering inverter 44, a steering transmission mechanism 46, and a conversion mechanism 48. The steering transmission mechanism 46 is made up of a belt transmission mechanism. The rotational power of the steering motor 42 is transmitted to the conversion mechanism 48 by the steering transmission mechanism 46. The conversion mechanism 48 converts the transmitted rotational power into displacement power in the axial direction of the rack shaft 32. The axial displacement of the rack shaft 32 causes the steerable wheels 34 to be turned.

[0010] The steering control device 50 controls the control amount of the steering wheel 12 and the steered wheels 34, which are the control objects. That is, the steering control device 50 controls the steering reaction force that resists the steering by the driver, which is the control amount of the steering wheel 12, which is the control object. The steering control device 50 also controls the steering angle, which is the control amount of the steered wheels 34, which are the control object. The steering angle is the turning angle of the tires, which are the steered wheels 34.

[0011] The steering control device 50 executes a process for learning the neutral position of the steering shaft 14 under predetermined conditions. The neutral position corresponds to the straight-ahead direction of the vehicle. As an example, the steering control device 50 detects the upper limit values ​​on the right-turning side and the left-turning side of the steering shaft 14, and determines the midpoint between them as the neutral position.

[0012] "Configuration of Reaction Force Actuator 20" Figure 2 shows the configuration of a portion of the reaction force actuator 20. As shown in Figure 2, the reaction force actuator 20 includes a housing 60 that is fixed to the vehicle body. The steering shaft 14 is inserted into the housing 60. The housing 60 supports the steering shaft 14 so that it can rotate. The steering shaft 14 is inserted into a plurality of ring-shaped members. The ring-shaped members include a washer 70, an intermediate stopper 80, a washer 72, an end stopper 90, a wave washer 74, and a C-shaped retaining ring 76.

[0013] The housing 60 is provided with a protrusion 62 as a rotation stopping portion that restricts the rotation of the intermediate stopper 80. As shown in Figure 3, the intermediate stopper 80 is provided with a protrusion 82 whose rotation is restricted by the protrusion 62. An O-ring 84 is fitted onto the protrusion 82. The O-ring 84 is made of rubber.

[0014] FIG. 4 shows a cross section taken along line 4-4 in FIG. 2. As shown in FIG. 4, an elastic force acting in the right direction in the figure is applied to the end stopper 90 by the wave washer 74. As a result, an elastic force acting in the right direction in the figure is applied to the intermediate stopper 80 via the washer 72. Meanwhile, the steering shaft 14 has a reduced diameter portion at the end on the left side in the figure. The washer 70, the intermediate stopper 80, and the washer 72 are disposed in the reduced diameter portion of the steering shaft 14. Therefore, displacement of the washer 70 to the right in the figure is restricted. Therefore, an elastic force acting in the right direction in the figure is applied to the intermediate stopper 80 by the washer 72, and an elastic force acting in the left direction in the figure is applied by the washer 70.

[0015] The end stopper 90 is fixed to the steering shaft 14 by serration fitting. Therefore, as the steering shaft 14 rotates, the end stopper 90 rotates integrally with the steering shaft 14. As the end stopper 90 rotates, the intermediate stopper 80 rotates as well. Therefore, the protrusion 82 constitutes an interlocking rotor that rotates around the axis of the steering shaft 14 in conjunction with the rotation of the steering shaft 14.

[0016] "Rotation restriction of steering shaft 14" The upper part of Fig. 5 shows a case where the steering shaft 14 rotates to the right turning side. The left end of the upper part of Fig. 5 shows a state where the steering angle θs, which is the rotation angle of the steering shaft 14, is a value corresponding to the end of the left turning side. The upper part of Fig. 5 also shows a state where the steering shaft 14 rotates to the right turning side as it moves to the right in the figure. In particular, the right end of the upper part of Fig. 5 shows a state where the steering angle θs is a value corresponding to the end of the right turning side.

[0017] As shown in the upper part of Figure 5, when the steering shaft 14 turns right from the end on the left turning side, the intermediate stopper 80 rotates as the end stopper 90 rotates. The center of the upper part of Figure 5 shows a state in which the protrusion 82 of the intermediate stopper 80 contacts the protrusion 62 of the housing 60 via the O-ring 84. This prevents the intermediate stopper 80 from turning further to the right. Therefore, the end stopper 90 rotates independently as the steering shaft 14 rotates. Then, as the steering shaft 14 rotates further, the protrusion 92 of the end stopper 90 contacts the protrusion 82 of the intermediate stopper 80, preventing the end stopper 90 from turning further to the right. This state is shown at the right end of the upper part of Figure 5. In this state, the steering shaft 14 cannot rotate further to the right. The steering angle θs at this time is the upper limit on the right turning side.

[0018] The lower part of Fig. 5 shows a case where the rotation angle of the steering shaft 14 rotates to the left turning side. The left end of the lower part of Fig. 5 shows a state where the steering angle θs is a value corresponding to the end of the right turning side. The lower part of Fig. 5 also shows a state where the steering shaft 14 rotates to the left turning side as it moves to the right in the figure. In particular, the right end of the lower part of Fig. 5 shows a state where the steering angle θs is a value corresponding to the end of the left turning side.

[0019] As shown in the lower part of Figure 5, when the steering shaft 14 turns left from the end on the right-turning side, the intermediate stopper 80 rotates as the end stopper 90 rotates. The center of the lower part of Figure 5 shows a state in which the protrusion 82 of the intermediate stopper 80 contacts the protrusion 62 of the housing 60 via the O-ring 84. This prevents the intermediate stopper 80 from turning further left. Therefore, the end stopper 90 rotates independently as the steering shaft 14 rotates. Then, as the steering shaft 14 rotates further, the protrusion 92 of the end stopper 90 contacts the protrusion 82 of the intermediate stopper 80, preventing the end stopper 90 from turning further left. This state is shown at the right end of the lower part of Figure 5. In this state, the steering shaft 14 cannot rotate further to the left. The steering angle θs at this time is the upper limit on the left-turning side.

[0020] Note that Figure 5 illustrates an example in which the steering angle θs changes from one of two values, a value corresponding to the left-turning end and a value corresponding to the right-turning end, to the other. However, in reality, it is rare for the steering angle θs to reach a value corresponding to either the left-turning end or the right-turning end. The steering angle θs usually fluctuates within an intermediate region between the value corresponding to the left-turning end and the value corresponding to the right-turning end. In this case, the intermediate stopper 80 is rotated along with the rotation of the end stopper 90 when the protrusion 92 of the end stopper 90 is not in contact with the protrusion of the intermediate stopper 80.

[0021] "Suppression of impact sounds caused by collision between protrusion 82 and protrusion 92 and protrusion 62" Figure 6A shows a cross section taken along line 6-6 in Figure 3. That is, Figure 6A shows a cross section of the opposing portions of protrusion 82 and protrusion 62 that face each other when they come into contact with each other. The x-axis direction in Figure 6A indicates the direction of travel of protrusion 82 of intermediate stopper 80 just before it comes into contact with protrusion 62 of housing 60. More specifically, the direction of travel of protrusion 82 is the positive direction along the x-axis. The z-axis direction is the circumferential direction of O-ring 84. That is, the xy plane shown in Figure 6A is a plane perpendicular to the circumferential direction of O-ring 64.

[0022] 6A , a groove C is formed in the protrusion 82 of the intermediate stopper 80. An O-ring 84 is housed in the groove C. The groove C is formed in at least the opposing portion of the protrusion 82. However, when the protrusion 82 of the intermediate stopper 80 and the protrusion 62 of the housing 60 are separated from each other, the O-ring 84 protrudes from the groove C in the x-axis direction.

[0023] 6A shows the state when the protrusion 62 of the housing 60 comes into contact with the O-ring 84. In this state, the contact surface 62a of the protrusion 62 is not in contact with the contact surface 82a of the protrusion 82. Here, the contact surface 82a of the protrusion 82 is the portion adjacent to the groove C in the y-axis direction.

[0024] The right side of FIG. 6A shows a state in which the O-ring 84 is deformed, causing the abutment surface 62a of the protrusion 62 to come into contact with the abutment surface 82a of the protrusion 82. In this embodiment, in a cross section taken along the xy plane shown in FIG. 6A , the ratio of the cross-sectional area of ​​the O-ring 84 to the cross-sectional area of ​​the groove C is set to 0.7 or less. This ratio may be 0.5 to 0.7. This setting is intended to make the ratio smaller than the value used in typical O-ring 84 applications. That is, the O-ring 84 is typically used to improve sealing performance. In such cases, it is desirable for the O-ring 84 to fill the groove C without any gaps. In contrast, in this embodiment, the O-ring 84 is used to absorb impact. Therefore, by ensuring that the O-ring 84 is accommodated in the groove C with ample space, the durability of the O-ring 84 can be increased.

[0025] Furthermore, in this embodiment, in a cross section along the xy plane, the second dimension W of the groove C is larger than the first dimension D. The second dimension W is the dimension of the groove C along the second direction, which is the y-axis direction. The first dimension D is the dimension of the groove C along the first direction, which is the x-axis direction. This allows the O-ring 84 to easily expand in the y-axis direction within the groove C by being compressed.

[0026] 6B illustrates an example in which the ratio is 0.7 or more and the second dimension W is equal to the first dimension D. In this case, the O-ring 84 is compressed and a large strain occurs, which may reduce the durability of the O-ring 84.

[0027] <Operations and Effects of the Present Embodiment> When the steering wheel 12 is operated, the end stopper 90 rotates in conjunction with the steering shaft 14. This causes the intermediate stopper 80 to rotate along with it. When the intermediate stopper 80 is displaced to the position shown in the upper center of Fig. 5 or the lower center of Fig. 5, the protrusion 82 of the intermediate stopper 80 comes into contact with the protrusion 62 of the housing 60, thereby restricting further rotation of the intermediate stopper 80. At this time, the O-ring 84 provided in the groove C of the intermediate stopper 80 comes into contact with the abutment surface 62a of the protrusion 62, thereby suppressing hitting noise.

[0028] On the other hand, when the steering control device 50 learns the neutral position of the steering shaft 14, the steering control device 50 performs a large turn operation on the steering shaft 14. As a result, the end stopper 90 is displaced to the position shown at the right end of the upper part of FIG. 5 or the right end of the lower part of FIG. 5. As a result, the protrusion 92 of the end stopper 90 comes into contact with the protrusion 82 of the intermediate stopper 80, thereby restricting further rotation of the end stopper 90. At this time, if the steering control device 50 applies a large force to further rotate the steering shaft 14, the O-ring 84 deforms, causing the abutment surface 82a of the protrusion 82 of the intermediate stopper 80 to come into contact with the abutment surface 62a of the protrusion 62 of the housing 60. Furthermore, as shown in FIG. 7, the deformation of the O-ring 84 causes the abutment surface 82a of the protrusion 82 of the intermediate stopper 80 to come into contact with the abutment surface 92a of the protrusion 92 of the end stopper 90.

[0029] In this way, when learning the neutral position, the contact surface 82a of the protrusion 82 of the intermediate stopper 80 comes into contact with both the contact surface 62a of the protrusion 62 of the housing 60 and the contact surface 92a of the protrusion 92 of the end stopper 90. Therefore, compared to a case where they do not come into contact, the upper limit values ​​on the right-turning side and the left-turning side of the steering shaft 14 can be detected with high accuracy.

[0030] The above embodiment also provides the following advantageous effects. (1-1) The rubber O-ring 84 is used as a member that absorbs the impact when the protrusion 82 of the intermediate stopper 80 comes into contact with the protrusion 62 of the housing 60 and the protrusion 92 of the end stopper 90. Because the O-ring 84 is made of rubber, it has not only elasticity but also viscosity. In other words, the O-ring 84 has a repulsive force that is positively correlated with the displacement speed. Therefore, the above-mentioned impact can be sufficiently absorbed.

[0031] Second Embodiment A second embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment.

[0032] In this embodiment, an O-ring 84 is not provided on the protrusion 82 of the intermediate stopper 80. Instead, as shown in FIG. 8 , an O-ring 64 is provided on the protrusion 62 of the housing 60. Specifically, a groove is formed in the protrusion 62, and the O-ring 64 is housed in the groove. Here, the cross-sectional area of ​​the O-ring 64 in a predetermined plane perpendicular to the circumferential direction of the O-ring 64 is 70% or less of the cross-sectional area of ​​the groove C in the same predetermined plane. Furthermore, a first dimension D, which is the dimension of the groove C in the depth direction, is smaller than a second dimension W, which is the dimension of the groove C in the width direction.

[0033] <Other Embodiments> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0034] "Device for restricting rotation of steering shaft 14" The configuration in which the intermediate stopper 80 rotates in conjunction with the rotation of the end stopper 90 is not limited to a configuration that utilizes the frictional force between the intermediate stopper 80 and the end stopper 90. For example, the configuration may be such that the protrusion 92 of the end stopper 90 presses the protrusion 82 of the intermediate stopper 80 in conjunction with the rotation of the end stopper 90, causing the intermediate stopper 80 to rotate. In this case, when the protrusion 82 of the intermediate stopper 80 comes into contact with the protrusion 62 of the housing 60, stopping the rotation of the intermediate stopper 80, the rotation of the end stopper 90 is also stopped.

[0035] The device for restricting the rotation of the steering shaft 14 is not limited to the device exemplified in the above embodiment. For example, the device may include a plurality of intermediate stoppers as second rotating members that rotate in conjunction with the rotation of the end stopper 90 as the first rotating member. Here, a case where a first intermediate stopper and a second intermediate stopper are provided will be described as an example. In this case, the first intermediate stopper and the second intermediate stopper are rotated in conjunction with the rotation of the end stopper 90. Then, the protrusion of the first intermediate stopper comes into contact with the protrusion 62 serving as a rotation stopping portion of the housing 60, thereby preventing the rotation of the first intermediate stopper. As a result, only the second intermediate stopper is rotated in conjunction with the rotation of the end stopper 90. Then, the protrusion of the second intermediate stopper comes into contact with the protrusion of the first intermediate stopper, thereby preventing the rotation of the second intermediate stopper. As a result, the end stopper 90 rotates independently. Then, the protrusion 92 of the end stopper 90 comes into contact with the protrusion of the second intermediate stopper, thereby preventing the rotation of the end stopper 90. That is, further rotation of the steering shaft 14 is prevented.

[0036] Regarding the Elastic Member: In the second embodiment, a groove may also be provided in the protrusion 92 of the end stopper 90, and an O-ring may be housed in the groove.

[0037] The groove and O-ring may be provided only on the protrusion 92 of the end stopper 90. The elastic member is not limited to the O-rings 84 and 64. For example, it may be rubber provided only in the area surrounded by the contact surface 82 a in Fig. 6A and the area surrounded by the contact surface 82 a in Fig. 7.

[0038] The elastic member does not necessarily have to be rubber. Even in this case, if the elastic member has not only elasticity but also viscosity, it can reduce impact more than when the elastic member does not have viscosity. However, it is not essential that the elastic member has viscosity.

[0039] Regarding the groove: In a cross section perpendicular to the circumferential direction of the O-ring, the ratio of the cross-sectional area of ​​the O-ring to the cross-sectional area of ​​the groove does not necessarily have to be 0.7 or less. Even if the ratio is greater than 0.7, the abutment surface 62a and the abutment surface 82a can be brought into contact with each other, as shown in FIG. 6B.

[0040] It is not essential that the second dimension W along the width direction of the groove C be greater than the first dimension D along the depth direction. For example, even if the second dimension W and the first dimension D are equal, the abutment surface 62 a and the abutment surface 82 a can be brought into contact with each other, as illustrated in FIG. 6B .

[0041] "Others" - In each of the above embodiments, the steering device 10 has a linkless structure in which the steering wheel 12 and the steered wheels 34 are mechanically separated at all times, but this is not limited to this, and the steering device 10 may have a structure in which the steering wheel 12 and the steered wheels 34 can be mechanically separated by a clutch.

[0042] In this specification, "at least one of A and B" should be understood to mean "A only, B only, or both A and B."

Claims

1. A steering device having a steering shaft that can be operated when power transmission from the steered wheels of a vehicle is cut off, comprising: an interlocking rotor that rotates around the axis of the steering shaft in conjunction with the rotation of the steering shaft; and a rotation stopping part that stops the interlocking rotor by coming into contact with the interlocking rotor, wherein the interlocking rotor has an opposing part that faces the rotation stopping part when it comes into contact with the rotation stopping part, and the rotation stopping part has an opposing part that faces the interlocking rotor when it comes into contact with the interlocking rotor, at least one of the opposing part of the interlocking rotor and the opposing part of the rotation stopping part is provided with a groove and an elastic member attached to the groove, and the opposing part of the interlocking rotor and the opposing part of the rotation stopping part have abutment surfaces that are configured to be able to come into contact with each other when the elastic member is deformed.

2. A steering device according to claim 1, wherein said elastic member is a member having both viscosity and elasticity.

3. A steering device according to claim 1, wherein said elastic member is an O-ring.

4. A steering device according to claim 3, wherein the ratio of the cross-sectional area of ​​said O-ring to the cross-sectional area of ​​said groove in a cross section taken along a plane perpendicular to the circumferential direction of said O-ring is 0.7 or less.

5. A steering device as described in claim 3, wherein a first dimension which is the dimension of the groove along a first direction is smaller than a second dimension which is the dimension of the groove along a second direction, the first direction is a direction in which the abutment surface of the interlocking rotating body is displaced when the abutment surface of the interlocking rotating body and the abutment surface of the rotation stop portion transition from a contacting state to a non-contacting state in a cross section along a plane perpendicular to the circumferential direction of the O-ring, and the second direction is a direction perpendicular to the first direction in a cross section along a plane perpendicular to the circumferential direction of the O-ring.

6. A steering device as described in claim 1, comprising: a first rotating member connected to the steering shaft; and a second rotating member that rotates in conjunction with the rotation of the steering shaft, wherein the interlocking rotating body is provided on the second rotating member, and the first rotating member is configured such that rotation in the specified direction is prevented when the first rotating member is in contact with the second rotating member while rotation of the second rotating member in the specified direction is prevented by the rotation stopping portion.

7. A steering device according to claim 1, wherein said elastic member is provided on said interlocking rotor.

8. A steering device according to claim 1, wherein said elastic member is provided at said rotation stopping portion.

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