JP3529637B2 - Vehicle steering system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering system capable of steering a rotary operation member such as a steering wheel without mechanically connecting it to a steering gear.

[0002]

2. Description of the Related Art The movement of a steering actuator driven in response to an operation of a rotary operation member is transmitted to wheels so that a steering angle is changed by a steering gear. There is a steering apparatus for a vehicle that can steer a rotary operation member without mechanically connecting it to a steering gear.

If the rotary operation member is not mechanically connected to the steering gear as described above, the rotary operation member cannot be returned to the straight steering position by the self-aligning torque. Therefore, in order to return the rotary operation member to the straight-ahead steering position, it is necessary to apply elasticity by the elastic member (Japanese Patent Laid-Open No. 9-142330).

Conventionally, since the elastic force applied by the elastic member is directly applied by the spiral spring, the elastic force F is zero when the rotational operation angle θ of the operating member is zero, as shown in FIG. It was

However, with the conventional configuration, it is difficult to accurately return the rotary operation member to the straight-ahead steering position, and there is a problem that the rigidity at the straight-ahead steering position is insufficient.

In order to solve such a problem, there is a conventional technique for applying a resistance force to a rotary operation member by utilizing the viscous resistance of a fluid (Japanese Patent Laid-Open No. 153379/1990), but the structure is extremely complicated and it is manufactured. The cost increases.

An object of the present invention is to provide a vehicle steering system which can solve the above problems.

[0008]

According to the present invention, the movement of a steering actuator driven in response to an operation of a rotary operation member is transmitted to wheels so that a turning angle is changed by a steering gear. The present invention is applied to a steering device for a vehicle that can steer a rotary operation member without mechanically connecting it to a steering gear. According to the present invention, an elastic member that gives an elastic force to return the rotary operation member to the straight steering position, a screw shaft supported on the vehicle body side so as to rotate together with the rotary operation member, and screwed to the screw shaft. A nut, a mechanism that allows the nut to move in the axial direction with respect to the vehicle body side, and prevents rotation of the shaft center, a first slider that is displaceable in the axial direction of the screw shaft, and a displaceable in the axial direction of the screw shaft And a second slider.
The elastic member is arranged so that the first slider exerts an elastic force toward one end of the screw shaft and the second slider exerts an elastic force toward the other end of the screw shaft. When the rotation operating member is in the straight-ahead steering position, each slider is pressed against the vehicle body side member by the elastic force of the elastic member, and the displacement of the nut toward the other end of the screw shaft is restricted via the first slider, The displacement of the nut toward one end of the screw shaft is restricted via the second slider. By the left steering, against the elasticity of the elastic member, the nut and the first
The slider is allowed to be displaced toward the other end of the screw shaft, and by right steering, the nut and the second slider are allowed to be displaced toward one end of the screw shaft along with the elasticity of the elastic member. Has been done.

According to the structure of the present invention, when the rotary operation member is operated to the left steering state, the nut is displaced toward the other end of the screw shaft together with the first slider due to the rotation of the screw shaft. When the rotation operation member is operated to the right steering state, the nut is displaced together with the second slider toward one end of the screw shaft due to the rotation of the screw shaft. When the steering force is released during left steering, the elastic force of the elastic member is applied to the nut toward one end of the screw shaft through the first slider, and when the steering force is released during right steering, the elastic force is applied through the second slider. Is applied toward the other end of the screw shaft.
The elastic force causes the screw shaft to rotate so that the rotation operating member moves toward the straight steering position. When the rotation operating member reaches the straight-ahead steering position, both sliders are pressed against the vehicle body side member by its elasticity, so that the rotation operating member can be accurately positioned at the straight-ahead steering position. Further, at the straight-ahead steering position, the elastic force restricts the displacement of the nut toward the other end of the screw shaft via the first slider and the displacement of the nut toward the one end of the screw shaft via the second slider. It This allows
A force that holds the rotary operation member at the straight-ahead steering position acts, and a sense of rigidity at the straight-ahead steering position can be secured.

Both sliders are arranged in parallel along the axial direction of the screw shaft and have a ring shape fitted to the outer circumference on the nut side, and the elastic member surrounds the outer circumference on the nut side between the sliders. The vehicle body side member has first and second blocking surfaces against which the respective sliders are pressed by the elastic force when the rotation operating member is in the straight steering position, and both blocking surfaces are formed of compression coil springs. , The slider and the compression coil spring are located between them, and the nut side has a first receiving surface on which the first slider is pressed by the elastic force during left steering, and a second slider is pressed by the elastic force during right steering. And a second receiving surface that is
Both sliders and the compression coil spring are arranged between them, and when the rotation operation member is in the straight steering position, the first receiving surface is the first blocking surface, the second receiving surface is the second blocking surface, and the screw It is preferable that they are arranged at the same position in the axial direction of the shaft. As a result, both sliders and the compression coil spring are held by the nut side, and when the rotation operating member is in the straight steering position, the first receiving surface is the first blocking surface and the second receiving surface is the second blocking surface. Since the screw shafts are arranged at the same position in the axial direction, the configuration can be simplified, and further, the axial dimension can be made as small as possible and the configuration can be made compact.

It is preferable that the displacement of the nut can be prevented by the vehicle body side member so that the steering limit is regulated. This simplifies the structure because the steering limit can be easily defined, and the steering limit can be easily changed by only changing the displacement preventing position of the nut.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the vehicle steering system shown in FIG. 1, the steering gear 3 changes the steering angle of the movement of a steering actuator 2 which is driven in response to an operation of a steering wheel (rotating operation member) 1. As described above, the steering wheel 1 is steered without being mechanically connected to the steering gear 3.

That is, the steering gear 3 has a motion converting mechanism for converting the rotational motion of the output shaft of the steering actuator 2 into the linear motion of the steering rod 7. The motion of the steering rod 7 is the tie rod 8. It is transmitted to the wheels 4 via the knuckle arm 9. The steering actuator 2 can be composed of, for example, an electric motor such as a known brushless motor, and a known steering gear 3 can also be used. The point is that the movement of the steering actuator 2 is changed by turning the wheels 4. The structure is not limited as long as it can be converted into a corner.

The steering wheel 1 has a rotating shaft 10 rotatably supported by the vehicle body side.
The detection signal of the rotation angle detection sensor 11 of the rotary shaft 10 and the vehicle speed detection signal of the speed sensor 13 are
It is sent to the control device 12 which is composed of a computer. The control device 12 calculates a target turning angle according to the detected rotation angle and vehicle speed. For example, the target steered angle is made proportional to the rotation angle, and the proportional constant is decreased as the vehicle speed increases. In addition, a sensor that detects a running state other than the vehicle speed, such as lateral acceleration, may be provided, and the target turning angle may be changed according to the detected value. An actual steering amount sensor 14 such as a potentiometer for detecting the operation amount of the steering rod 7 is provided, and a detection signal thereof 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 turning angle corresponding to the detected operation amount of the steering rod 7 and the target turning angle is eliminated. A reaction force actuator 21 that applies a torque to the rotating shaft 10 is provided to apply a steering reaction force required to steer the steering wheel 1. The reaction force actuator 21 can be configured by an electric motor such as a brushless motor having an output shaft integrated with the rotation shaft 10. The control device 12 calculates a target reaction force torque according to the detected rotation angle and the detected vehicle speed, and the reaction force actuator 21 generates the target reaction force torque so that the reaction force actuator 21 generates the target reaction force torque. Are driven via the drive circuit 22. The relationship between the target reaction force torque, the rotation angle, and the vehicle speed is, for example, the relationship between the steering resistance torque from the road surface, which acts when the steering wheel 1 and the steering gear 3 are mechanically connected, the steering angle, and the vehicle speed. Based on. Also,
A sensor for detecting 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. A torque sensor 23 for detecting the reaction torque transmitted by the rotary shaft 10 is provided, and the detection signal is sent to the control device 12. The control device 12 controls the drive current of the steering actuator 2 so that the steering force generated by the steering actuator 2 corresponds to the detected reaction torque. That is,
If the reaction torque corresponding to the operating force applied by the driver is increased, the steering force generated by the steering actuator is increased, and if the reaction torque is decreased, the steering force generated by the steering actuator is decreased. As a result, the steering actuator 2 is not driven when the driver is not applying the operating force, and the wheels 4 return to the straight traveling state by the self-aligning torque. A well-known control system can be used for the steering actuator 2 and the reaction force actuator 21, and the configuration is not limited as long as the steering actuator can be driven according to the operation of the rotary operation member.

An elastic force applying mechanism 3 having an elastic member for applying an elastic force for returning the steering wheel 1 to the straight steering position when the driver is not applying an operating force.
0 is provided.

As shown in FIG. 2, the elastic force imparting mechanism 30 is provided.
Is a cylindrical housing 32 that is integral with the ball screw shaft 31, a casing 29 that covers the screw shaft 31 and covers the rotary shaft 10, and is inserted into one end side (upper side in FIG. 2) of the housing 32. It has a first stopper 33 and a second stopper 34 inserted into the other end side (lower side in FIG. 2) of the housing 32 thereof. The screw shaft 31 has one end side (upper side in FIG. 2) on which the rotary shaft 10 is connected.
The steering wheel 1 is rotated together with the steering wheel 1 by being integrated with the steering wheel 1. Both stoppers 33, 34 are cylindrical and have inwardly directed flanges 33 ', 34' directed radially inward.
And are arranged at intervals in the axial direction of the screw shaft 31 with respect to each other. The housing 32 is fixed to the vehicle body by, for example, bolts, and the stoppers 33, 3 are
4 is fixed to the housing 32, for example, by being press-fitted, whereby the housing 32 and the stoppers 3 are fixed.
3, 34 are members on the vehicle body side. The screw shaft 31 includes the casing 29 and the second stopper 3
It is supported on the vehicle body side via bearings 35 and 36 fitted to the vehicle body 4.

A ball 38 is attached to the screw shaft 31.
The ball nut 39 is screwed through the. The nut 39 includes a main body 39a, a tubular member 39b that is integrated by being press-fitted into the outer periphery of the main body 39a, and first and second protrusions outwardly from both outer peripheries of the tubular member 39b. Flanges 39c, 39d and the tubular member 3 thereof
It has a retaining member 39e that is integrated by being press-fitted to the inner periphery of 9b. The tubular member 39b is formed by, for example, screwing two members 39b 'and 39b "together, and has sliders 41 and 42 and a spring 43, which will be described later, on the outer periphery thereof.
(Elastic member) can be fitted.

Each flange 39c, 39 of the nut 39
The outer periphery of d and the inner periphery of each of the stoppers 33 and 34 face each other and are along a non-circular shape, for example, a polygonal shape so as to be relatively movable in the axial direction of the screw shaft 31 and not to rotate relative to the axial center. It is said that. As a result, the nut 39 is allowed to move in the axial direction with respect to the vehicle body side, and rotation about the axis is prevented. The mechanism for permitting the axial movement and preventing the rotation about the axial center is not particularly limited. For example, a guide pin fixed to the vehicle body side is axially moved relative to the axial groove formed on the nut side. It may be configured by being inserted so as to be capable of relative movement in the circumferential direction.

A ring-shaped first slider 41 and a ring-shaped second slider 42 are displaceable in the axial direction of the screw shaft 31 and their radial displacement is restricted on the outer periphery of the tubular member 39b on the side of the nut 39. It is fitted like. Both sliders 41 and 42 are screw shafts 31
Are arranged in parallel with each other at intervals along the axial direction of. The elastic member is arranged between the sliders 41 and 42 so as to surround the outer circumference on the nut 39 side.
It is composed of three. For each slider 41, 42,
The cylindrical portions 41a, 42 extending toward the inside of the spring 43
a is formed. The spring 43 is sandwiched between the two sliders 41 and 42, so that the spring 43 applies an elastic force to the first slider 41 toward one end of the screw shaft 31 (toward the upper side in FIG. 2), and causes the second slider 42 to screw. An elastic force is applied toward the other end of the shaft 31 (downward in FIG. 2).

The sliders 41 and 42 and the spring 43 are arranged between the stoppers 33 and 34, which are members on the vehicle body side. The first stopper 33 has a first blocking surface 33 a facing the first slider 41. The second stopper 34 is the second blocking surface 34 facing the second slider 42.
a. Both blocking surfaces 33a and 34a are arranged so that both sliders 41 and 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. At this time, the elasticity of the spring 43 presses the first slider 41 against the first blocking surface 33a and the second slider 42 moves to the second It is pressed against the blocking surface 34a.

Further, both sliders 41 and 42 and spring 43
Are the flanges 39c and 39d on the nut 39 side.
Placed between. The first flange 39c has a first receiving surface 39c 'that faces the first slider 41. The second flange 39d has a second receiving surface 39d 'facing the second slider 42. Both receiving surfaces 39c ', 39
The d'is arranged so that the sliders 41 and 42 and the spring 43 are located between them. When the steering wheel 1 is in the straight steering position, the first receiving surface 39c 'is the first blocking surface 33a and the second receiving surface 39d' is the second blocking surface 34a.
And are arranged at the same position in the axial direction of the screw shaft 31.

When the steering wheel 1 is in the straight-ahead steering position, the first receiving surface 39c 'on the side of the nut 39 contacts the first slider 41, and the elastic force of the spring 43 causes the other end of the screw shaft 31 to move. The displacement of the nut 39 toward (toward downward in FIG. 2) is the first
It is regulated via the slider 41. Further, when the steering wheel 1 is in the straight-ahead steering position, the second receiving surface 39d ′ on the side of the nut 39 contacts the second slider 42, so that the elastic force of the spring 43 moves it toward one end of the screw shaft 31. The displacement of the nut 39 (upward in FIG. 2) is restricted via the second slider 42.

By the left steering, the nut 39 and the first slider 41 are displaced together toward the other end of the screw shaft 31 (downward in FIG. 2) against the elastic force of the spring 43. Figure 3 shows the state of left steering,
At this time, the elasticity of the spring 43 causes the first slider 41 to move.
Is pressed against the first receiving surface 39c '. In the present embodiment, the nut 39 is in contact with the inward flange 34 ′ of the second stopper 34 to prevent the operation of the steering wheel 1 and reach the left steering limit.
That is, the left steering limit can be defined by preventing the displacement of the nut 39 by the inward flange 34 'of the second stopper 34 which is the vehicle body side member. The left steering limit is
For example, it can be changed by interposing a shim 70a between the inward flange 34 'and the nut 39 as shown by a chain double-dashed line in FIG. 2 and changing the displacement preventing position of the nut 39.

Further, when the steering wheel is turned to the right, the nut 39 and the second slider 42 are displaced together toward the one end of the screw shaft 31 (upward in FIG. 2) against the elastic force of the spring 43. FIG. 4 shows the state at the time of right steering. At this time, the second slider 42 is pressed against the second receiving surface 39d 'by the elastic force of the spring 43. In the present embodiment, the nut 39 is in contact with the inward flange 33 'of the first stopper 33 to prevent the operation of the steering wheel 1 and reach the right steering limit. That is, the first stopper 3 that is the vehicle body side member
The right steering limit can be defined by preventing the displacement of the nut 39 by the inwardly facing flange 33 'of No. 3. The right steering limit can be changed, for example, by interposing a shim 70b between the inward flange 33 'and the nut 39 as shown by a chain double-dashed line in FIG. 2 and changing the displacement preventing position of the nut 39.

According to the above structure, when the steering wheel 1 is rotated to the left steering state, the rotation of the screw shaft 31 causes the nut 39 to move to the first slider 41.
At the same time, the screw shaft 31 is displaced toward the other end. When the steering wheel 1 is rotationally operated to the right steering state, the rotation of the screw shaft 31 causes the nut 39 to move together with the second slider 42 and the screw shaft 3.
It is displaced toward one end of 1. When the steering force is released during left steering, the elastic force of the spring 43 is applied to the nut 39 through the first slider 41 toward one end of the screw shaft 31, and when the steering force is released during right steering, the elastic force is reduced to the second.
It is applied to the nut 39 via the slider 42 toward the other end of the screw shaft 31. The elastic force causes the screw shaft 31 to rotate so that the steering wheel 1 moves toward the straight steering position. When the steering wheel 1 reaches the straight-ahead steering position, the elasticity causes the sliders 41 and 42 to move toward the stopper 33, which is a vehicle body side member.
Since the steering wheel 1 is pressed against the first and second blocking surfaces 33a and 34a of the steering wheel 34, the steering wheel 1 can be accurately positioned at the straight steering position. Further, at the straight-ahead steering position, the elastic force restricts the displacement of the nut 39 toward the other end of the screw shaft 31 via the first slider 41, and the displacement of the nut 39 toward the one end of the screw shaft 31 occurs at the second slider. Regulated via 42. As a result, as shown in FIG. 5, even when the rotational operation angle θ of the steering wheel 1 is zero, the elastic force F that returns the steering wheel 1 to the straight-ahead steering position becomes the force that holds the steering wheel 1 at the straight-ahead steering position. To work. Further, according to the above configuration, both sliders 41, 4
2 and the compression coil spring 43 are held by the nut 39 side, and when the steering wheel 1 is in the straight steering position, the first receiving surface 39c 'is the first blocking surface 33a.
The second receiving surface 39d 'is arranged at the same position as the second blocking surface 34a in the axial direction of the screw shaft 31, so that the structure can be simplified and the axial dimension can be made as small as possible to make the structure compact. Can be realized. Further, since the steering limit can be specified only by preventing the displacement of the nut 39 by the member on the vehicle body side, the configuration can be simplified, and
The steering limit can also be changed easily by changing the displacement prevention position of the nut 39.

The present invention is not limited to the above embodiment. For example, the rotation operation member is not limited to the steering wheel, and may have the same form as a handle of a motorcycle. A spring other than the compression coil spring, rubber, or the like may be used as the 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.

[0027]

According to the present invention, when the rotating operation member is steered without being mechanically connected to the steering gear, the rotating operation member can be accurately returned to the straight steering position after steering. It is possible to provide a compact vehicle steering system capable of ensuring a sense of rigidity at a straight steering position.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of a steering device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part of the steering apparatus according to the embodiment of the present invention during straight steering.

FIG. 3 is a cross-sectional view of a main part of the steering device according to the embodiment of the present invention during left steering.

FIG. 4 is a cross-sectional view of a main part of the steering device according to the embodiment of the present invention during right steering.

FIG. 5 is a diagram showing the relationship between the elastic force for returning the rotary operation member of the steering device of the present invention to the straight steering position and the rotary operation angle.

FIG. 6 is a diagram showing a relationship between an elastic force for returning a rotary operation member of a conventional steering device to a straight steering position and a rotary operation angle.

[Explanation of symbols]

1 steering wheel 2 Steering actuator 3 steering gear Four wheels 30 Elasticity imparting mechanism 31 screw shaft 33, 34 First and second stoppers (body-side member) 33a, 34a First and second blocking surfaces 39 nuts 39c ', 39d' First and second receiving surfaces 41, 42 First and second sliders 43 Spring (elastic member)

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-11-78947 (JP, A) JP-A-11-1174 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B62D 5/04 B62D 5/06 B62D 6/00

Claims (3)

(57) [Claims] 1. A rotary operation member is transmitted to a steering gear by transmitting the movement of a steering actuator driven according to the operation of the rotary operation member to a wheel so that the steering angle is changed by the steering gear. In a steering device of a vehicle that can be steered without being mechanically coupled, an elastic member that gives an elastic force to return the rotary operation member to a straight steering position, and a rotation member that rotates together with the elastic operation member. A screw shaft supported on the vehicle body side, a nut screwed onto the screw shaft, a mechanism that allows the nut to move axially with respect to the vehicle body side, and prevents rotation of the axial center, and an axial direction of the screw shaft. A displaceable first slider and a displaceable second slider in the axial direction of the screw shaft, The elastic member is arranged so as to exert an elastic force on the first slider toward one end of the screw shaft and an elastic force on the second slider toward the other end of the screw shaft, and the rotation operation member is set to the straight steering position. At a certain time, each slider is pressed against the vehicle body side member by the elastic force of the elastic member, the displacement of the nut toward the other end of the screw shaft is regulated via the first slider, and the nut toward the one end of the screw shaft is regulated. Displacement is regulated via the second slider, and by left steering, the nut and the first slider can move together toward the other end of the screw shaft against the elastic force of the elastic member, and by right steering. , The nut and the second slider accompany the elastic force of the elastic member, and A steering device for a vehicle, wherein the steering device can be displaced in the opposite direction. 2. The two sliders have a ring shape arranged in parallel along the axial direction of the screw shaft and fitted to the outer circumference on the nut side, and the elastic member surrounds the outer circumference on the nut side between the sliders. The vehicle body side member has first and second blocking surfaces against which the sliders are pressed by the elastic force when the rotation operating member is in the straight-ahead steering position. The surface is arranged so that both sliders and the compression coil spring are located between them, and the nut side has a first receiving surface on which the first slider is pressed by the elastic force at the time of left steering, and a second slider at the time of right steering. A second receiving surface that is pressed by the two receiving surfaces, and the both receiving surfaces are arranged so that the slider and the compression coil spring are located between them. The first receiving surface is arranged at the same position as the first blocking surface and the second receiving surface is arranged at the same position in the axial direction of the screw shaft when the rotary operating member is in the straight steering position. The vehicle steering system described. 3. The vehicle steering system according to claim 1, wherein displacement of the nut can be prevented by a member on the vehicle body side so that a steering limit is defined.