JP2005047338A - Steering device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device for a vehicle to work by a mechanical reaction force generated by the resilient force of a spring etc. and an electric reaction force given by a reaction force motor etc. which are changed over from one to the other according to a situation. <P>SOLUTION: The steering device for the vehicle is equipped with a steering shaft 10 coupled with an operating member of the vehicle, the reaction force motor to give a steering reaction force to the steering shaft 10 in accordance with operation applied to the steering member, a failure sensing means 57 to sense a failure in the motor, a reaction force giving means 30 to give a reaction force caused by resilience to the steering shaft 10, and a wheel steering means not coupled mechanically with the steering shaft 10, wherein the reaction force giving means has a resilient piece 43 to generate the reaction force caused by resilience, an engaging means 45 engaged with the resilient piece 43 so as not to generate the reaction force caused by resilience, and an engaging member separating means to separate the engaging member 45 from the resilient piece 43 when a failure is sensed in the motor by the sensing means 57. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle steering apparatus in which a steering member such as a steered wheel is not mechanically connected to a wheel steering mechanism that changes the direction of a wheel.
[0002]
[Prior art]
In recent years, steer-by-wire steering devices have been used for the purpose of increasing the degree of freedom in the layout of the interior of the vehicle interior, expanding the space in the vehicle interior, and preventing the steering wheel from being pushed up. A steer-by-wire type steering device is a vehicle steering device that can steer wheels without mechanically connecting a steering member such as a steering wheel to a wheel steering mechanism such as a steering gear.
[0003]
Since the steer-by-wire steering device does not mechanically connect the steering member to a wheel steering mechanism such as a steering gear, the steering member cannot be returned to the straight steering position by self-aligning torque. Therefore, in order to return the steering member to the straight steering position, an appropriate reaction force is applied by the elastic member.
[0004]
For example, Patent Document 1 discloses a steering device that can reliably transmit the rotational torque of a steering member to a wheel steering mechanism even when a motor malfunctions by an electromagnetic clutch.
[0005]
However, like the steer-by-wire type steering device disclosed in Patent Document 2, when the reaction force motor is arranged outside the passenger compartment and connected by a transmission cable, a reaction force is applied when a failure occurs in the transmission cable. Can not do it. In view of this, usually, reaction force applying means using mechanical elastic force is separately provided.
[0006]
For example, Patent Document 3 includes a sensor that detects a steering rotation angle of a steering wheel, a sensor that detects a vehicle speed, and a sensor that detects an actual steering angle, and calculates a deviation between the steering rotation angle of the steering wheel and the actual steering angle. A steering device is disclosed that produces a suitable reaction torque that minimizes and returns to the neutral position of the steering shaft.
[0007]
[Patent Document 1]
Japanese Utility Model Publication No. 61-48870 [Patent Document 2]
JP 2002-225733 A [Patent Document 3]
Japanese Patent Laid-Open No. 2000-53008
[Problems to be solved by the invention]
However, if both a mechanical reaction force using an elastic force such as a spring and an electric reaction force applied by a reaction force motor or the like are applied simultaneously, the reaction force that controls the magnitude of the electric reaction force is controlled. Control of the force motor becomes difficult. That is, the rotational torque of the steering member can be easily detected by a torque sensor, but it is difficult to accurately detect the mechanical reaction torque using the elastic force of a spring or the like. In some cases, there is a possibility that the electrical reaction force applied in (1) is excessively applied in some cases, and in other cases (in other words, it is excessively low).
[0009]
In addition, when a failure occurs in the reaction force motor or the like, it is also necessary to construct some kind of backup system in order to continue driving the vehicle safely.
[0010]
The present invention has been made in view of such circumstances, and a mechanical reaction force using an elastic force such as a spring and an electric reaction force applied by a reaction force motor or the like depending on the situation. An object of the present invention is to provide a vehicle steering apparatus that can be switched.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a vehicle steering apparatus according to a first aspect of the present invention includes a steering shaft coupled to an operation member of a vehicle, and a reaction force motor that applies a steering reaction force to the steering shaft in accordance with an operation of the operation member. An abnormality detecting means for detecting an abnormality of the reaction force motor, a reaction force applying means for applying an elastic reaction force to the steering shaft, and a wheel steering means not mechanically connected to the steering shaft. In the vehicle steering apparatus, the reaction force applying means includes: an elastic body that generates an elastic reaction force; an engagement member that is engaged with the elastic body so as not to generate an elastic reaction force; and the abnormality detection unit. An engagement member detachment means for detaching the engagement member from the elastic body when an abnormality of the reaction motor is detected is provided.
[0012]
In the vehicle steering apparatus according to the first aspect of the present invention, when it is detected that an abnormality has occurred in the reaction force motor, the engagement member engaged with the elastic body such as the spring of the reaction force applying means is detached, and the spring or the like Since a mechanical reaction force utilizing the elasticity of the vehicle can be applied, even if an abnormality occurs in the reaction force motor during the traveling of the vehicle, it is possible to travel safely.
[0013]
According to a second aspect of the present invention, there is provided the vehicle steering apparatus according to the first aspect, wherein the engagement member detaching means connects the engagement member and the operation member, and the engagement member is operated according to an operation of the operation member. It is a wire for detaching the member from the elastic body.
[0014]
In the vehicle steering apparatus according to the second aspect of the present invention, the engaging member engaged with the reaction force applying means for applying a mechanical reaction force by a spring or the like is connected to the operation member by a wire. By rotating the wire and winding the wire, the engaging member can be easily detached from the reaction force applying means, and a mechanical reaction force using elastic force such as a spring can be reliably applied. It becomes.
[0015]
According to a third aspect of the present invention, there is provided the vehicle steering apparatus according to the second aspect, wherein the engaging member disengaging means includes at least an electromagnetic clutch and two pulleys, the pulley including a driving member on a connection surface of the electromagnetic clutch. Arranged on the driven member, one pulley is connected to the operation member and the other pulley is connected to the engaging member via the wire, respectively, and the abnormality detecting means detects an abnormality of the reaction force motor. In this case, it is characterized by comprising connection means for connecting the electromagnetic clutch.
[0016]
In the vehicle steering device according to the third aspect of the invention, when the electromagnetic clutch is not normally connected, only the electric reaction force by the reaction force motor is applied, and when it is detected that an abnormality has occurred in the reaction force motor, By connecting the electromagnetic clutch and rotating the operating member to wind the wire, the engaging member is detached from the reaction force applying means, and the mechanical reaction using the elastic force of the spring of the reaction force applying means is used. It is possible to grant only power.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic diagram showing an overall configuration of a vehicle steering apparatus according to an embodiment of the present invention. In FIG. 1, the steering wheel (operation member) 1 is not mechanically connected to the steering gear 3, and the steering actuator 2 is driven according to the operation of the steering wheel 1.
[0018]
The steering gear 3 has a motion conversion mechanism as wheel steering means for converting the rotational motion of the output shaft of the steering actuator 2 into the linear motion of the steering rod 7. The movement of the steering rod 7 is transmitted to the wheel 4 through the tie rod 8 and the knuckle arm 9. As the steering actuator 2, for example, an electric motor such as a brushless motor may be used as long as the movement of the steering actuator 2 can be converted into the steering angle of the wheel 4.
[0019]
The steering wheel 1 has a steering shaft 10 that is rotatably supported on the vehicle body side. A detection signal by the rotation angle detection sensor 11 of the steering shaft 10 and a vehicle speed detection signal by the speed sensor 13 are sent to a control device 12 constituted by a computer. The control device 12 calculates a target turning angle according to the detected rotation angle and vehicle speed. For example, the target turning angle is made proportional to the detected rotation angle, and the proportionality constant is decreased as the vehicle speed increases. In addition, a sensor that detects a traveling state other than the vehicle speed, for example, lateral acceleration or the like may be provided, and the target turning angle may be changed according to the detected lateral acceleration or the like.
[0020]
On the other hand, an actual steering amount sensor 14 such as a potentiometer for detecting the operation amount of the steering rod 7 is provided, and the detected signal is sent to the control device 12. The control device 12 drives the steering actuator 2 via the drive circuit 15 so that the deviation between the actual steering angle corresponding to the detected operation amount of the steering rod 7 and the target steering angle is eliminated.
[0021]
In addition, a reaction force actuator 18 that adds torque to the steering shaft 10 is provided in order to apply a steering reaction force required to steer the steering wheel 1. The reaction force actuator 18 uses an electric motor such as a brushless motor having an output shaft integrated with the steering shaft 10 as a reaction force motor.
[0022]
The control device 12 calculates a target reaction force torque according to the detected rotation angle and the detected vehicle speed, and via the drive circuit 16 so that the calculated target reaction force torque is generated by the reaction force actuator 18. The reaction force actuator 18 is driven. The relationship between the target reaction torque, the rotation angle, and the vehicle speed is, for example, the relationship between the steering resistance torque from the road surface that acts when the steering wheel 1 and the steering gear 3 are mechanically connected, the steering angle, and the vehicle speed. Ask based. Further, a sensor that detects a running state other than the vehicle speed, such as lateral acceleration, may be provided, and the target reaction force torque may be changed according to the detected value.
[0023]
A torque sensor 17 that detects the reaction force torque transmitted by the steering shaft 10 is provided, and the detected reaction force torque value is sent to the control device 12. The control device 12 controls the drive current of the steering actuator 2 output from the drive circuit 15 so that the generated steering force of the steering actuator 2 corresponds to the detected reaction force torque. That is, if the reaction torque corresponding to the operating force applied by the driver increases, the generated steering force of the steering actuator 2 is increased, and if the reaction torque decreases, the generated steering force of the steering actuator 2 is decreased. . By doing so, the steering actuator 2 is not driven in a state where the driver does not apply the operating force, and the wheel 4 returns to the straight traveling state by the self-aligning torque. The control system for the steering actuator 2 and the reaction force actuator 18 may be a known control system, and is not particularly limited as long as the steering actuator 2 can be driven according to the operation of the rotary operation member.
[0024]
When the driver of the car is not steering the steering wheel 1, it is preferable to give elasticity to return the steering wheel 1 to the straight steering position from the viewpoint of safety. Therefore, a reaction force applying mechanism 30 having an elastic member for applying such a reaction force is provided.
[0025]
FIG. 2 shows a sectional view in the axial direction of the steering shaft 10 of the reaction force application mechanism (reaction force application means) 30. As shown in FIG. 2, the reaction force applying mechanism 30 includes a ball screw shaft 31, a cylindrical housing 32 that is integrated with a casing 29 that covers the screw shaft 31 and covers the steering shaft 10, and one end side of the housing 32. It has the 1st stopper 33 inserted in (upper side of FIG. 3), and the 2nd stopper 34 inserted in the other end side (lower side of FIG. 3) of this housing 32. As shown in FIG.
[0026]
The screw shaft 31 is integrated so as to be coaxial with the steering shaft 10 on one end side (the upper side in FIG. 3). Both stoppers 33 and 34 are cylindrical, have inward flanges 33 ′ and 34 ′ directed radially inward, and are arranged at an axial interval of the screw shaft 31. The housing 32 is fixed to the vehicle body by bolts, for example, and the stoppers 33 and 34 are fixed by being press-fitted into the housing 32, for example. The screw shaft 31 is supported on the vehicle body side via bearings 35 and 36 fitted to the casing 29 and the second stopper 34.
[0027]
A ball nut 39 is screwed onto the screw shaft 31 via a ball 38. The ball nut 39 includes a main body 39a, a cylindrical member 39b that is integrated by being press-fitted into the outer periphery of the main body 39a, and first and second flanges 39c that protrude outward from the outer periphery of both ends of the cylindrical member 39b. 39d and a retaining member 39e integrated by being press-fitted into the inner periphery of the cylindrical member 39b. The cylindrical member 39b is configured by, for example, screwing together two members 39b ′ and 39b ″, and sliders 41 and 42 (to be described later) and a spring 43 (elastic member) can be fitted to the outer periphery.
[0028]
The ring-shaped first slider 41 and the ring-shaped second slider 42 are fitted on the outer periphery of the cylindrical member 39b on the ball nut 39 side so as to be displaceable in the axial direction of the screw shaft 31 and to restrict radial displacement. Combined. Both sliders 41 and 42 are arranged in parallel with each other along the axial direction of the screw shaft 31. The elastic member is constituted by a compression coil spring 43 disposed between the sliders 41 and 42 so as to surround the outer periphery on the nut 39 side. The sliders 41 and 42 are formed with cylindrical portions 41 a and 42 a extending toward the inside of the spring 43. When the spring 43 is sandwiched between the sliders 41 and 42, the spring 43 causes the first slider 41 to be elastic toward one end of the screw shaft 31 (upward in FIG. 3) and the second slider 42 to the screw shaft. The elastic force toward the other end of 31 (downward in FIG. 3) is applied.
[0029]
Both sliders 41 and 42 and the spring 43 are arranged between both stoppers 33 and 34 which are vehicle body side members. The first stopper 33 has a first blocking surface 33 a that faces the first slider 41. The second stopper 34 has a second blocking surface 34 a that faces the second slider 42. Both blocking surfaces 33a, 34a are arranged such that both sliders 41, 42 and spring 43 are located between them. FIG. 2 shows a state in which the steering wheel 1 is in the straight steering position. The first slider 41 is pressed against the first blocking surface 33a by the elasticity of the spring 43, and the second slider 42 is pressed against the second blocking surface 34a. It is done.
[0030]
The sliders 41 and 42 and the spring 43 are disposed between the flanges 39c and 39d on the ball nut 39 side. The first flange 39 c has a first receiving surface 39 c ′ that faces the first slider 41. The second flange 39 d has a second receiving surface 39 d ′ that faces the second slider 42. Both the receiving surfaces 39c ′ and 39d ′ are arranged so that the sliders 41 and 42 and the spring 43 are located therebetween. When the steering wheel 1 is in the straight steering position, the first receiving surface 39c ′ is disposed at the same position in the axial direction of the screw shaft 31 as the first blocking surface 33a and the second receiving surface 39d ′ is positioned at the second blocking surface 34a. Is done.
[0031]
If the mechanical reaction force by the reaction force application mechanism 30 described above is applied while the reaction force by the reaction force motor is applied, rotation control of the reaction force motor becomes difficult. Therefore, while the reaction force by the reaction force motor is applied, it is necessary to restrict the mechanical reaction force by the reaction force application mechanism 30 described above from being applied. Therefore, in the present embodiment, the stopper (engaging member) 45 is engaged so as to sandwich the spring 43 so that the spring (elastic body) 43 of the reaction force applying mechanism 30 does not function. FIG. 3 shows a perspective view of a schematic configuration of the stopper 45.
[0032]
As shown in FIG. 3, the stopper 45 can be engaged with a part of the casing 29 of the reaction force applying mechanism 30, and includes wedge-shaped portions 46 that sandwich the spring 43 at both ends. A wire 47 is connected to the surface opposite to the wedge-shaped portion 46, and the wire 47 is coupled to the electromagnetic clutch mechanism 50.
[0033]
FIG. 4 shows a schematic sectional view of the electromagnetic clutch mechanism (engagement member detaching means) 50. As shown in FIG. 4, the wire 47 connected to the stopper 45 is hooked on one pulley 51 and interlocks with the first shaft (driven member) 52. The first shaft 52 and the second shaft (drive member) 53 are connected to or disconnected from each other when the armature 55 is attracted to or separated from the friction plate 54 by the magnetic force generated by the coil 56. That is, the coil 56 functions as a means for connecting the electromagnetic clutch mechanism 50. The other pulley 51 is also provided at the end of the second shaft 53, and a wire 47 connected to a steering mechanism such as the steering wheel 1 is latched.
[0034]
The electromagnetic clutch mechanism 50 controls the magnetic flux generated by the coil 56 according to whether or not an abnormality of the reaction force actuator 18 is detected. Regarding the abnormality of the reaction force actuator 18, the reaction force actuator 18 is provided with an abnormality detection mechanism (abnormality detection means) 57, and the control device 12 receives a signal indicating the rotation state of the reaction force motor and is driven from the drive circuit 16. If a signal indicating the rotation state of the reaction force motor cannot be received despite the current being supplied, it is determined that an abnormality has occurred in the reaction force actuator 18.
[0035]
In the electromagnetic clutch mechanism 50, when the abnormality detection mechanism 57 does not detect the abnormality of the reaction force actuator 18, the coil 56 does not generate a magnetic flux and the armature 55 is not attracted. Therefore, even if the steering wheel 1 is rotated, the wire 47 connected to the stopper 45 is not wound, and only the reaction force by the steering actuator 2 is applied.
[0036]
When the abnormality detection mechanism 57 detects an abnormality in the reaction force actuator 18, the coil 56 generates a magnetic flux and attracts the armature 55. Therefore, when the steering wheel 1 is rotated, the wire 47 connected to the stopper 45 is wound around the pulley 51 of the electromagnetic clutch mechanism 50, and the stopper 45 is detached from the reaction force applying mechanism 30. Since the stopper 45 is detached from the reaction force applying mechanism 30, the movement of the spring 43 is not restricted, and a mechanical reaction force is generated from the reaction force applying mechanism 30 even if the reaction force by the steering actuator 2 is not applied. Is granted.
[0037]
As described above, according to the present embodiment, when there is no failure in the reaction force motor, only the electric reaction force by the reaction force motor can be applied, and it is applied by another mechanism. The magnitude of the reaction force can be appropriately controlled without considering interference with the reaction force. On the other hand, even when an abnormality occurs in the reaction force motor during traveling, a mechanical reaction force using an elastic force such as a spring can be applied, so that the reaction force is reliably applied to the steering mechanism. It is possible to travel more safely.
[0038]
The present invention is not limited to the above embodiment. For example, the steering mechanism is not limited to the steering wheel, and may be the same form as the handle of a two-wheeled vehicle, for example. Moreover, you may use springs, rubber | gum, etc. of types other than a compression coil spring as an elastic member. Further, instead of the ball screw shaft and the ball nut, a general screw shaft and nut that directly mesh with each other may be used. Needless to say, the lead angle of the screw shaft is determined so that the torque required to rotate the screw shaft is generated by the elastic force acting on the nut.
[0039]
A method of reducing the probability of failure of the electric motor used for the steering actuator 2 and the reaction force actuator 18 is also effective in increasing the safety of the steer-by-wire type steering apparatus. Hereinafter, a method of reducing the probability of failure of the electric motor will be described by taking the case of the steering actuator 2 as an example.
[0040]
FIG. 5 is a schematic diagram of a steering mechanism including a steering actuator 2 in which a plurality of electric motors are used as a method for reducing the probability of occurrence of a failure in the electric motor. As shown in FIG. 5, in addition to the electric motor 61 that is normally used, an electric motor 62 for standby is further provided, and electromagnetic clutches 63 and 64 are provided between the electric motors 61 and 62 and the steering actuator 2.
[0041]
If the electric motors 61 and 62 are simply mechanically connected in parallel to the steering actuator 2 and one of them fails, the other is substituted. There is a problem that it is difficult to perform proper rotation control on the electric motor 61 used for driving the steering actuator 2 due to mutual inertia.
[0042]
Therefore, in the present embodiment, electromagnetic clutches 63 and 64 are provided between the electric motors 61 and 62 and the steering actuator 2. Normally, only the electric motor 61 is connected to the steering actuator 2 by connecting the electromagnetic clutch 63 and releasing the electromagnetic clutch 64. When any failure occurs in the electric motor 61, the electromagnetic clutch 63 is opened and the electromagnetic clutch 64 is connected, so that the standby electric motor 62 is connected to the steering actuator 2.
[0043]
In this way, the influence of the inertia of the electric motor 62 not used for driving the steering actuator 2 on the steering actuator 2 can be reduced, and the electric motor 61 used for driving the steering actuator 2 can be reduced. Even if a failure occurs, the standby electric motor 62 can be easily switched, so that the motor relay can be omitted from the electric motor drive circuit included in the steering actuator 2, and more It is possible to reduce the probability of failure of the electric motor with a simple mechanism.
[0044]
In the above-described example, a case where a plurality of electric motors are used for driving the steering actuator 2 has been described. However, even when applied to the reaction force actuator 18, the same effect can be expected with the same configuration. .
[0045]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to apply only an electric reaction force by a reaction force motor, and even if an abnormality occurs in the reaction force motor during running, Since the mechanical reaction force using the elastic force can be applied, the reaction force can be reliably applied to the steering mechanism, and the vehicle can travel more safely.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an overall configuration of a vehicle steering apparatus according to an embodiment of the present invention.
FIG. 2 is a sectional view in the axial direction of a steering shaft of a reaction force application mechanism.
FIG. 3 is a perspective view showing a schematic configuration of a stopper.
FIG. 4 is a schematic sectional view of an electromagnetic clutch mechanism.
FIG. 5 is a schematic view of a steering mechanism including a steering actuator having a plurality of electric motors.
[Explanation of symbols]
1 Steering wheel (operation member)
2 Steering actuator 10 Steering shaft 18 Reaction force actuator (Reaction force motor)
30 reaction force application mechanism (reaction force application means)
43 Spring (elastic body)
45 Stopper (engaging member)
47 Wire 50 Electromagnetic clutch mechanism (engaging member disengaging means)
51 Pulley 52 First shaft (driven member)
53 Second shaft (drive member)
56 Coil 57 Abnormality detection mechanism (abnormality detection means)

Claims (3)

A steering shaft coupled to a vehicle operating member;
A reaction force motor that applies a steering reaction force to the steering shaft in accordance with the operation of the operation member;
An abnormality detection means for detecting an abnormality of the reaction force motor;
Reaction force applying means for applying an elastic reaction force to the steering shaft;
In a vehicle steering apparatus comprising wheel steering means not mechanically connected to the steering shaft,
The reaction force applying means is
An elastic body that generates a reaction force due to elasticity;
An engaging member engaged with the elastic body so as not to generate a reaction force due to elasticity;
A vehicular steering apparatus, comprising: an engagement member detachment unit configured to detach the engagement member from the elastic body when the abnormality of the reaction force motor is detected by the abnormality detection unit. The engagement member detaching means is a wire that connects the engagement member and the operation member and causes the engagement member to be detached from the elastic body in accordance with an operation of the operation member. The vehicle steering apparatus according to claim 1. The engaging member detachment means includes at least an electromagnetic clutch and two pulleys, and the pulleys are respectively disposed on a driving member and a driven member of the electromagnetic clutch,
One pulley is connected to the operation member, and the other pulley is connected to the engaging member via the wires,
The vehicle steering apparatus according to claim 2, further comprising a connection unit that connects the electromagnetic clutch when the abnormality of the reaction force motor is detected by the abnormality detection unit.

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