JPH082434A - Vehicle steering device - Google Patents

Abstract

PURPOSE:To provide a vehicle steering device with high safety, capable of suppressing steering only when required. CONSTITUTION:A vehicle steering device 1 comprises a steering auxiliary force suppressing device 8 installed in a power assistant device 7, a forward monitoring device 9 containing a forward obstacle detecting device 10, side backward obstacle detecting devices 13, a dangerous state judging part 18, a steering angle detecting device 14 for detecting W operation of a driver, and a steering controller 19. When a driver conducts turning operation, a dangerous state does not exist in the forward direction of a vehicle and a dangerous state exists in the side backward direction of the vehicle, the steering auxiliary force suppressing device 8 is made in a steering auxiliary suppressing state which does not give steering auxiliary force corresponding to the steering force of a steering wheel 6.

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.

[0002]

2. Description of the Related Art A steering device for a vehicle equipped with a power assist device for assisting the steering force of a steering wheel can steer with a light operating force, so that the vehicle steering device can be used particularly when traveling at high speed on a highway. There is a problem that there is a high risk of causing a collision by making a so-called lane change in which the lane (vehicle lane) is changed without noticing an approaching vehicle on the rear side of the vehicle (side rear). Therefore, when an obstacle such as another vehicle traveling behind the vehicle is detected and the driver tries to steer in the direction of the obstacle, the steering assist force of the power assist device is reduced to A vehicle steering system has been proposed in which the rudder steering force is made heavy so that the driver can recognize a danger, and the steering operation in a dangerous direction can be suppressed to prevent a collision with another vehicle ( (See Japanese Patent Laid-Open No. 19274/1992).

[0003]

In the above vehicle steering system, the steering assist force is controlled only by the presence / absence of an obstacle on the rear side of the vehicle. Therefore, there are the following problems.

That is, first, even if an obstacle is detected on the rear side of the vehicle, it is not known whether the obstacle is moving away from or approaching the vehicle. Therefore, in any case, the steering assist is suppressed. Will end up. Therefore, even when it is unnecessary to suppress the steering such that the obstacle moves away from the vehicle, the steering is suppressed, and the driver feels uncomfortable and anxious. Especially,
Even if there is an obstacle such as a preceding vehicle in front of the vehicle, steering is suppressed even if there is an obstacle behind the side and the obstacle behind this side is not dangerous, so avoid the obstacle in front Can be difficult. Also, if the obstacle detection range is limited to the rear side of the adjacent lane, it cannot handle vehicles approaching from the other lane, and if the obstacle detection range is expanded to multiple lanes, Steering is suppressed simply because there is a vehicle in the lane beyond, and the above-mentioned problem occurs. Therefore, on roads with three or more lanes, danger cannot be prevented, or steering is suppressed even when unnecessary.

The same problem also occurs in the case of a vehicle steering system that is not equipped with a power assist device, that is, a so-called manual steering system.

The object of the present invention is to solve the above problems,
An object of the present invention is to provide a highly safe vehicle steering system capable of suppressing steering only when necessary.

[0007]

According to a first aspect of the present invention, there is provided a vehicle steering system including a power assist device for assisting a steering force of a steering wheel. , A steering assist force suppressing means for switching between a steering assist state in which a steering assist force according to the steering force of the steering wheel is applied and a steering assist restraint state in which a steering assist force according to the steering force of the steering wheel is not applied, and the front of the vehicle Front monitoring means including front obstacle detecting means for detecting obstacles, side rear obstacle detecting means for detecting obstacles on the side of the vehicle, and front of the vehicle is dangerous based on the output from the front obstacle detecting means. In addition to determining whether the vehicle is in a state, it is also determined whether the vehicle is in a dangerous state on the side or the rear side based on the output from the side or rear obstacle detecting means. Hazardous condition determining means, the operation detecting means detects that a predetermined operation of the driver has been performed, and predetermined operation of the driver is performed, the front of the vehicle is not dangerous state,
In addition, when the vehicle rear side is in a dangerous state, the steering assist suppression control is performed to keep the steering assist suppression unit in the steering assist suppressed state for at least a predetermined time, and at other times, the steering assist force suppression unit is in the steering assist state. It is characterized in that it is provided with a steering control means for carrying out steering assist control.

For the front obstacle detecting means and the rear obstacle detecting means, for example, a distance measuring device using a radar,
Known appropriate devices such as an ultrasonic distance measuring device, a one-dimensional image pickup device such as a line sensor, and a two-dimensional image pickup device such as a television camera are used.

The dangerous state determining means determines whether the front of the vehicle is in a dangerous state, for example, as follows. That is, the distance to the front obstacle is obtained from the output of the front obstacle detection means, and when this distance is smaller than a predetermined value, it is determined that the dangerous state. Alternatively, the relative velocity (or acceleration) of an obstacle ahead of the own vehicle is calculated from the output of the front obstacle detection means, and if the state remains as it is, the own vehicle collides with the obstacle. The predicted time is calculated, and when the predicted collision time is smaller than the predetermined value, it is determined that the collision state is dangerous. Alternatively, the distance to the front obstacle and the relative velocity vector (or acceleration vector) of the obstacle with respect to the own vehicle are obtained from the output of the front obstacle detection means, and this distance is smaller than a predetermined value,
And when the relative speed vector points toward the vehicle,
Determined to be in a dangerous state.

The same applies to the determination of the dangerous state on the side of the vehicle.

For example, when the steering assist suppressing control is performed by the steering control means, the steering assist force suppressing means applies the steering reaction force to the power assist device.

For example, a steering angle storage means for storing the steering angle before the start of steering is provided, and when the steering assist suppression control is performed by the steering control means, the steering assist force suppression means stores the stored steering assist force before steering. The power assist device is controlled so that the steering angle is obtained.

For example, the front monitoring means includes a traveling road recognizing means for recognizing the shape of the traveling road in front of the vehicle, and when the steering assist suppressing control is performed by the steering control means, the steering assist force suppressing means recognizes it. After controlling the power assist device so that the vehicle follows the traveled road, the steering assist state is set. A one-dimensional image pickup device such as a line sensor or a two-dimensional image pickup device such as a television camera is used as the traveling path recognition means.

For example, the front monitoring means includes a preceding vehicle traveling direction detecting means for detecting the traveling direction of the preceding vehicle relative to the own vehicle, and when the steering assist suppressing control is performed by the steering control means, the steering assist force is controlled. After the suppressing means controls the power assist device so that the vehicle follows the preceding vehicle, the steering assist state is set. As the preceding vehicle traveling direction detecting means, for example, a one-dimensional image pickup device such as a line sensor or a two-dimensional image pickup device such as a television camera is used.

A vehicle steering system according to a sixth aspect of the present invention is
Front monitoring means including front obstacle detection means for detecting obstacles in front of the vehicle, side rear obstacle detection means for detecting obstacles on the side of the vehicle, and vehicle front based on output from the front obstacle detection means Dangerous state determination means for determining whether the front side is in a dangerous state and determining whether the side rear side of the vehicle is in a dangerous state based on the output from the side and rear obstacle detection means, the predetermined operation of the driver An operation detecting means for detecting that the operation is performed, and a predetermined operation of the driver is performed,
Steering control means that applies a steering reaction force to the steering mechanism when the front side of the vehicle is not in a dangerous state and the side rear side of the vehicle is in a dangerous state and does not apply the steering reaction force to the steering mechanism at other times. It is characterized by having.

[0016]

According to the first aspect of the present invention, the steering assist suppression control is performed only when the predetermined operation of the driver is performed, the front side of the vehicle is not in a dangerous state, and the side rear side of the vehicle is in a dangerous state. Be seen. Therefore, the steering assist is not suppressed when unnecessary. In cases other than the above, for example, when the front of the vehicle is in a dangerous state, steering assist control is performed and normal steering by the power assist device is possible. Therefore, the obstacle in front cannot be avoided by suppressing the steering assist.

A steering angle storage means for storing the steering angle before the start of steering is provided, and when the steering assist suppressing control is performed by the steering control means, the steering assist force suppressing means stores the stored steering angle before steering. If the power assist device is controlled so that, the danger can be avoided more reliably.

The front obstacle detecting means includes a traveling road recognizing means for recognizing the shape of the traveling road in front of the vehicle, and when the steering assist suppressing control is performed by the steering control means, the steering assist force suppressing means recognizes it. If the steering assist state is set after the power assist device is controlled so that the vehicle follows the traveled road, the vehicle will not be off the traveled road and become more dangerous.

The front obstacle detecting means includes a preceding vehicle traveling direction detecting means for detecting a traveling direction of the preceding vehicle relative to the own vehicle. When the steering assist suppressing control is performed by the steering control means, the steering assist force is detected. After the suppressing means controls the power assist device so that the vehicle follows the preceding vehicle,
As long as the vehicle is in the steering assist state, the vehicle will not be deviated from the traveling direction of the preceding vehicle to be in a more dangerous state.

According to the sixth aspect of the present invention, the steering reaction force is applied to the steering mechanism only when the predetermined operation of the driver is performed, the front side of the vehicle is not in a dangerous state, and the side rear side of the vehicle is in a dangerous state. Is given. Therefore, the steering reaction force is not applied when unnecessary. In cases other than the above, for example, when the front of the vehicle is in a dangerous state, the steering reaction force is not applied and normal steering is possible. Therefore, the obstacle ahead cannot be avoided by applying the steering reaction force.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a vehicle and a steering device mounted on the vehicle.
One example of (1) is schematically shown, and FIG. 2 shows one example of the configuration of the main part of the steering system (1).

In FIG. 1, (2) is the vehicle body, (3) is the front wheels, (4) is the rear wheels, (5) is the rack rod, (6) is the steering wheel (steering wheel), and (7) is the power. It is an assist device. By operating the handle (6) the rack bar
(5) moves left and right to steer the front wheels (3), and the power assist device (7) assists the steering force of the steering wheel (6).

As will be described in detail later, the power assist device (7) includes a steering assist state in which a steering assist force corresponding to the steering force of the steering wheel (6) is applied and a steering assist according to the steering force of the steering wheel (6). There is provided a steering assist force suppressing device (8) which constitutes a steering assist force suppressing means capable of switching to a steering assist suppressing state in which an assist force is not applied.

At the front of the vehicle body (2), there is provided a front monitoring device (9) which constitutes a front monitoring means for monitoring the front of the vehicle. The front monitoring device (9) is provided with a front obstacle detecting device (10) which constitutes a front obstacle detecting means for detecting an obstacle in front of the vehicle. Further, the front monitoring device (9) includes a traveling road recognition device (11) that composes a traveling road recognition means for recognizing the shape of the traveling road ahead of the vehicle and a relative position of the preceding vehicle relative to the own vehicle, if necessary. There is provided a preceding vehicle traveling direction detecting device (12) which constitutes a preceding vehicle traveling direction detecting means for detecting various traveling directions. The sensor of the front obstacle detection device (10), for example, a distance measuring device using a radar,
An ultrasonic distance measuring device, a one-dimensional image pickup device such as a line sensor, or a two-dimensional image pickup device such as a television camera is used. As the sensors of the traveling road recognition device (11) and the preceding vehicle traveling direction detection device (12), for example, a one-dimensional image pickup device such as a line sensor or a two-dimensional image pickup device such as a television camera is used.

Note that some of these detection devices (10), (11) and (12) may share the sensor part.

On both sides of the vehicle body (2), there are provided side-rear obstacle detection devices (13) constituting side-rear obstacle detection means for detecting an obstacle behind the vehicle. Examples of the sensor of the rear side obstacle detection device (13) include a distance measuring device using a radar, an ultrasonic distance measuring device, a one-dimensional image pickup device such as a line sensor, and a two-dimensional image pickup device such as a television camera. used.

At a suitable position of the vehicle body (2), for example, a rack bar
A steering angle detection device (14) for detecting the steering angle of the steering wheel (6), that is, the front wheels (3) by detecting the amount of movement of (5) is provided. The rudder angle detecting device (14) may be
An operation detecting unit for detecting that a predetermined operation of the driver, which will be described later, is performed is configured.

A vehicle speed detecting device (15) for detecting the speed (vehicle speed) of the vehicle is provided at an appropriate position on the vehicle body (2).

Further, the vehicle has a power assist device (7) based on the outputs of the front monitoring device (9), the side rear obstacle detecting device (13), the steering angle detecting device (14) and the vehicle speed detecting device (15). )
There is provided a control unit (16) for controlling the. The control unit (16) is composed of, for example, a microcomputer, and includes a rudder angle storage unit (17) that constitutes rudder angle storage means, and a dangerous state determination unit that constitutes dangerous state determination means.
A steering control section (19) which constitutes the steering control means (18) is provided. The output of the front monitoring device (9) is the judgment unit (18).
And input to the control unit (19). Side rear obstacle detection device (1
The output of 3) is input to the determination unit (18). Rudder Angle Detector (14)
The output of the steering angle storage unit (17), determination unit (18) and control unit (19)
And the output of the steering angle storage unit (17) is input to the control unit (19). The output of the vehicle speed detection device (15) is input to the control unit (19). Then, the power assist device (7) is controlled by the control unit (19).
The steering assist force suppressing device (8) is controlled. Judgment part (18)
Is to determine whether the front of the vehicle is in a dangerous state based on the output from the front obstacle detection device (10),
Based on the output from the side-rear obstacle detection device (13), it is determined whether the side-rear of the vehicle is in a dangerous state. The control unit (19) controls the steering assist force suppressing device (8) for at least a predetermined time when the driver's predetermined operation is performed, the front of the vehicle is not in a dangerous state, and the side behind the vehicle is in a dangerous state. Performs steering assist suppression control to enter the steering assist suppressed state,
At other times, the steering assist control is performed to bring the steering assist force suppressing device (8) into the steering assist state.

The main part of the power assist device (7) is shown in FIG. 3, and the main parts thereof are shown in FIGS. 4 to 6.

The power assist device (7) is a device in which the steering assist force suppressing device (8) is added to a known power assist portion having a rotary valve type control valve mechanism.

In the power assist device (7), (21) is an input shaft rotatably connected to the handle (6), and (22)
Is an output shaft connected to the input shaft (21) via a torsion bar (23), (24) is a valve body integrally fixed to the output shaft (22) by a pin (25), and (26) is a valve A known rotary valve mechanism formed between the inner periphery of the body (24) and the outer periphery of the input shaft (21), (27) is driven by an engine (not shown) to supply pressure oil to the valve mechanism (26). The main pump, (28) is an oil tank that receives return oil from the valve mechanism (26) through the return oil port (29), and (30) is a power cylinder for applying steering assist force to the rack rod (5). Is. The input shaft (21) and the output shaft (22) are rotatably supported by the housing (31). At the end of the output shaft (22), a pinion (22a) that meshes with the rack (5a) formed on the rack rod (5) is formed. The pressure oil from the main pump (27) is supplied to the valve mechanism (26) via the pressure oil port (32). If the handle (6) is not operated, the pressure oil supplied to the valve mechanism (26) will
As it is, it returns to the oil tank (28) from the return oil port (29), and the steering force is not assisted. When the steering wheel (6) is operated, the input shaft (21) and the output shaft (22) rotate, whereby the rack rod (5) moves and the front wheels (3) are steered.
At the same time, the torsion bar (23) is twisted, causing a relative angular displacement between the input shaft (21) and the output shaft (22), that is, the valve body (24), and the pressure oil supplied to the valve mechanism (26) is While being selectively supplied to one of the oil chambers (30a) and (30b) of the power cylinder (30), oil is returned from the other to the oil tank (28) to assist the steering force.

In FIG. 3, when the steering wheel is turned to the right, the pinion (22a) does not move with respect to the rotation of the input shaft (21) due to the steering resistance of the front wheels (3) (steering wheels). It does not rotate easily because it meshes with it. Therefore, torsional displacement occurs in the torsion bar (23) and rotational displacement occurs between the input shaft (21) and the valve body (24), and the main pump (27)
Pressure oil from the pressure oil port (32), cylinder port (46a),
It is supplied to the oil chamber (30a) on the left side of the power cylinder (30).
On the other hand, the return oil in the oil chamber (30b) on the right side of the power cylinder (30) is returned to the oil tank (28) from the oil chamber (30b) on the right side through the cylinder port (46b) and the return oil port (29). Be done. Then, the pressure oil supplied to the left oil chamber (30a) generates a steering assisting force in the right turning direction.

When the vehicle is steered to the left, conversely to the above, pressure oil is supplied to the oil chamber (30b) on the right side of the power cylinder (30), and the oil in the oil chamber (30a) on the left side is replenished with oil. Returning to the tank (28), steering assisting force in the left turning direction is generated.

The steering assist force suppressing device (8) comprises a first relative rotation suppressing mechanism (8a) for suppressing relative rotation between the input shaft (21) and the output shaft (22), the housing (31) and the output shaft. The second relative rotation suppressing mechanism (8b) for suppressing relative rotation of (22) is included. As will be described later in detail, the first relative rotation suppressing mechanism (8a) adjusts the steering assist force according to the vehicle speed, and the second relative rotation suppressing mechanism (8b) controls the steering device (8) to operate the steering wheel. Power assist device when switched to auxiliary suppression state
This is to apply a steering reaction force to (7).

As shown in FIGS. 3 and 4, the first relative rotation suppressing mechanism (8a) has a through hole (33) formed in the output shaft (22).
A plunger (34) with a spherical head portion (34a) and a plunger (34) slidably mounted on the input shaft (21)
It includes an oil chamber (35) through which pressure oil for pressure contact with is introduced. A plurality of through holes (33) are formed in a circumferential groove (36) formed on the outer periphery of the head of the output shaft (22) in a circumferentially even arrangement, and each penetrates the output shaft (22) in the radial direction. ing. An annular body (37) having a split is fitted in the circumferential groove (36) to restrict the outward movement of the plunger (34) in the radial direction. Oil chamber (3
5) is sealed by a pair of seal rings (38) (39) provided on both sides of the circumferential groove (36) between the outer circumference of the head of the output shaft (22) and the inner circumferential wall of the housing (31). It is formed in the formed state.

As shown in detail in FIG. 5, a groove (40) extending in the axial direction is formed on the outer periphery of one end side of the input shaft (21) corresponding to each plunger (34). The bottom of the groove (40) is an arc surface with a predetermined radius from the valve center, and the groove (40)
Between the both side surfaces of the valve and the spherical head (34a) of the plunger (34), the neutral position of the valve and the neutral position of the reaction force part (meaning the position where the hydraulic reaction force does not act on the relative displacement of the valve) A gap s corresponding to the amount of deviation considered in terms of machining accuracy is provided.

Pressure oil is supplied to the oil chamber (35) through the oil passage (43) branched from the oil passage (42) from the auxiliary pump (41) driven by the engine and the pressure oil port (44). It is supposed to be done. In the part of the oil passage (42) before branching to the oil passage (43),
A first control valve (45) including a solenoid is arranged, the opening of which is adjusted by a signal from the control section (19). When pressure oil is supplied to the oil chamber (35), the head portion (34a) of the plunger (34) is pressed against the bottom portion of the concave groove (40) of the input shaft (21) by a force corresponding to the pressure, Between the input shaft (21) and the output shaft (22),
Rotational resistance is generated according to the pressure contact force of the plunger (34).

As shown in detail in FIG. 6, the second relative rotation suppressing mechanism (8b) has a through hole (47) formed in the housing (31).
A plunger (48) in which the head (48a) is formed in a spherical shape slidably on the oil chamber (49) for introducing pressure oil for bringing the plunger (48) into pressure contact with the output shaft (22), And through hole (4
It is screwed into the inlet of (7) to form an oil chamber (49) in the through hole (47) between the plunger (48) and the plunger (48).
It includes a sealing screw member (50) for preventing the screw from coming off.

A plurality of through holes (47) are formed on the outer periphery of the housing (31) at equal intervals in the circumference, and each penetrates the housing (31) in the radial direction. The oil chamber (49) has a seal ring (39) (5) between the outer periphery of the output shaft (22) and the inner peripheral wall of the housing (31).
It is formed in a sealed state according to 1).

The oil chamber (49) has an oil passage from the auxiliary pump (41).
At (42), the pressure oil is supplied via the oil passage (52) branched from the portion downstream of the branched portion of the oil passage (43). Branch of oil passage (42) to oil passage (43) and oil passage
A second part including a solenoid, whose opening is adjusted by a signal from the control part (19), in a part between the branch part to (52) and the branch part.
The control valve (53) is arranged. When pressure oil is supplied to the oil chamber (49), the head (48a) of the plunger (48) is pressed against the outer peripheral surface of the output shaft (22) by a force corresponding to the pressure, and the housing (31) and Rotational resistance is generated between the output shaft (22) and the pressure contact force of the plunger (48).

When the vehicle is running, the opening of the second control valve (53) is switched by a signal from the control section (19) of the control unit (16), so that the oil chamber of the second relative rotation suppressing mechanism (8b) is changed.
The pressure of the pressure oil supplied to (49) is switched and the suppression device
(8) is switched between the steering assist state and the steering assist suppression state. Then, in the state where the suppressing device (8) is switched to the steering assist state, the opening degree of the first control valve (45) is controlled by a signal from the control unit (19) according to the vehicle speed, and as a result, 1 The pressure of the pressure oil supplied to the oil chamber (35) of the relative rotation suppressing mechanism (8a) is controlled, and the steering operation force (force required to steer the handle (6)) is adjusted according to the vehicle speed. To be done.

The control unit (19) switches the opening degree of the second control valve (53) to the smaller side when switching the suppressing device (8) to the steering assist state. Thereby, the second relative rotation suppressing mechanism
Since the pressure of the pressure oil supplied to the oil chamber (49) of (8b) becomes low and the pressure contact force of the plunger (48) with respect to the output shaft (22) becomes small, the output shaft (22) will be installed in the housing (31). On the other hand, it becomes a state in which it can freely rotate. The control unit (19) is in such a state,
According to the vehicle speed detected by the vehicle speed detection device (15), the first
The opening degree of the control valve (45) is controlled so as to increase as the speed increases. Therefore, the pressure contact force of the plunger (34) with respect to the input shaft (21) is controlled to increase as the speed increases, and as a result, the steering assist force decreases according to the vehicle speed, such that the steering assist force decreases as the speed increases. Be adjusted.

The control unit (19) fixes the opening degree of the first control valve (45) to a large constant value regardless of the vehicle speed when switching the suppression device (8) to the steering assist suppression state. The opening degree of the second control valve (53) is switched to the larger side.
As a result, the oil chambers (35) (49) of the relative rotation suppressing mechanism (8a) (8b)
The pressure of the pressure oil supplied to is increased. When the pressure of the pressure oil supplied to the oil chamber (35) of the first relative rotation suppressing mechanism (8a) increases, the rotation resistance against relative rotation between the input shaft (21) and the output shaft (22) increases, The steering assist force becomes smaller. Also,
When the pressure of the pressure oil supplied to the oil chamber (49) of the second relative rotation suppressing mechanism (8b) increases, the rotation resistance against relative rotation between the housing (31) and the output shaft (22) increases, and the handle (6)
The steering assist force corresponding to the steering force is not applied and the steering reaction force is applied.

In the above steering device, the front monitoring device (9), the side rear obstacle detection device (13), and the rear side obstacle detection device (13) are controlled by the determination unit (18) and the control unit (19) of the control unit (16) while the vehicle is traveling. The power assist device (7) is controlled based on the outputs of the steering angle detection device (14) and the vehicle speed detection device (15).

Next, referring to the flowchart of FIG.
An example of the operation of the determination unit (18) and the control unit (19) while the vehicle is traveling will be described.

When the vehicle is in a running state, it is first checked whether or not a predetermined operation of the driver is performed (step 1), and if the predetermined operation is performed, the process proceeds to step 2. The predetermined operation of the driver includes, for example, steering operation of the steering wheel (6), operation of a direction indicator, etc., and the steering wheel (6) is steered and the steering angle detected by the steering angle detector (14). It is determined that the predetermined operation has been performed when the corner has changed from the previous time or when the turn signal has been operated.

In step 2, the dangerous state of the rear side is judged based on the output of the rear side obstacle detecting device (13). An example of this determination process is shown in the flowchart of FIG. In FIG. 8, first, the steering direction is detected from the output of the steering angle detection device (14) (step 20
1). This is done by comparing the steering angle detected this time with the previous steering angle stored in the steering angle storage unit (17). Next, from the output of the side-rear obstacle detection device (13), the relative velocity vector of the object (obstacle) behind the steering direction side with respect to the own vehicle is detected (step 202), and the steering direction side rear is approached. It is checked whether there is an object (step 203).
If there is no approaching object in step 203, that is, if there is no object behind the steering direction side, or if there is an object but the vehicle is not approaching, it is determined that the vehicle is not in a dangerous state, and the process proceeds to step 204. Then, for example, the dangerous state flag on the rear side is set to the non-dangerous state, and the process ends. If there is an approaching object in step 203, that is, if there is an object behind in the steering direction and the relative velocity vector points toward the host vehicle, proceed to step 205 to determine whether there is a possibility of collision. Find out. In this, the distance to the object on the rear side is obtained from the output of the rear side obstacle detection device (13), and if it is smaller than a predetermined value, it is determined that there is a possibility of collision. Alternatively, from the distance to the object on the rear side and the relative velocity vector, the predicted collision time until reaching a collision when the state is maintained is obtained, and if this is smaller than a predetermined value, there is a risk of collision. to decide. If there is no risk of collision in step 205, the process proceeds to step 204. If there is a risk of collision in step 205, it is judged as a dangerous state,
Proceeding to step 206, for example, the dangerous state flag on the rear side is set to the dangerous state, and the process ends.

In FIG. 7, when the process of step 2 is completed, it is checked from the determination result in step 2 whether the rear side is in the dangerous state (step 3). If it is not in the dangerous state, the process proceeds to step 4. In step 4, it is checked whether or not the steering assist suppression control is in progress. If not, the processing is terminated as it is, and if the steering assist suppression control is in progress, the process proceeds to step 5 to cancel the steering assist suppression control. Switch to steering assist control, and the process ends. The steering assist suppressing control is the steering assist suppressing device (8) in the steering assist suppressing state, and as described above, the steering reaction force is applied to the steering assist suppressing device.
It means that the steering assist force corresponding to the steering force in (6) is not applied. Steering assist control is a steering assist force suppression device.
(8) is set to the steering assist state, and as described above, the steering reaction force is not applied and the steering assist force corresponding to the steering force of the steering wheel (6) and the vehicle speed is applied. When the process proceeds to step 4, if the steering assist control is being performed, it is continued as it is, and if the steering assist suppression control is being performed, the steering assist control is switched to the steering assist control state.

If the rear side is in a dangerous state in step 3, the process proceeds to step 6 and the front dangerous state is determined based on the output of the front monitoring device (9). This is done, for example, by checking whether there is an object approaching the host vehicle in front, and if there is an approaching object, for example, set a dangerous state flag in front to the dangerous state, and otherwise set it. Set to non-dangerous state.

Next, it is checked from the judgment result in step 6 whether or not the front side is in a dangerous state (step 7). If it is in a dangerous state, the process proceeds to step 8 and an alarm is issued, and then the process proceeds to step 4. As described above, the steering assist state is set, and the process ends.

If the front is not in a dangerous state in step 7, the process proceeds to step 9, the steering assist force suppressing device (8) is set in the steering assist suppressing state, the steering assist suppressing control is performed, and the process is ended.

As is apparent from the above description, even if the side rear side is in a dangerous state, if the front side is in a dangerous state, an alarm is issued and the steering assist suppressing control is not performed. Then, the steering assist suppression control is performed only when the side rear side is in the dangerous state and the front side is not in the dangerous state.

9 to 11 show another embodiment of the present invention. FIG. 9 shows an example of the configuration of the main part of the steering device. This steering device (55) is an electric power assist device (5
6) is equipped. 10 and 11 show an example of the configuration of the main part of the power assist device (56). 9 to 11, the same parts as those in the above embodiment are designated by the same reference numerals.

As shown in FIGS. 10 and 11, the power assist device (56) includes a DC motor (57), a reduction mechanism (58),
It has a powder clutch (59) and a pinion (60).
The motor (57) is arranged parallel to the rack bar (5).
The reduction mechanism (58) includes a worm shaft (58a) coaxially fixed to the drive shaft of the motor (57), and a worm wheel (58b) engaged with the worm shaft (58a). The clutch (59) has a hollow short cylindrical drive shaft (59a) formed integrally with the worm wheel (58b) and a driven shaft (59b) coaxially arranged inside the drive shaft (59a). Contains.
The clutch (59) has a known structure in which magnetic powder is interposed between the drive shaft (59a) and the driven shaft (59b),
By energizing a coil (not shown), the drive shaft (59a) and the driven shaft (59b) are connected by a predetermined connecting force according to the amount of energization. The speed reduction mechanism (58) and the clutch (59) are clutch
It is housed in the casing (62) together with the slip ring (61) that supplies current to the (59). The pinion (60) is fixed to the driven shaft (59b) and the top rack tooth (5) of the rack rod (5) is
b) mesh with.

Although illustration is omitted, a torque detecting device (63) (see FIG. 9) is attached to a predetermined position of the handle column. This torque detection device (63) controls the output according to the rotation direction of the steering wheel (6) and the load (steering torque).
Give to (19).

In this case, the motor (57), the reduction mechanism (58) and the clutch (59) of the power assist device (56) constitute a steering assist force suppressing device (64).

The control section (19) performs steering assist control by switching the steering assist force suppressing device (64) of the power assist device (56) to the steering assist state. In this case, the control unit (19)
Is a current supplied to the motor (57) and the clutch via a power supply circuit (not shown) according to the steering force of the steering wheel (6) and the vehicle speed.
Supply to (59). As a result, the rotational force of the motor (57) is transmitted to the rack rod (5) via the reduction mechanism (58), the clutch (59) and the pinion (60), and the steering force of the steering wheel (6) and the vehicle speed are adjusted. Steering assistance is provided. At this time, the clutch (59)
The steering assist force according to the load is applied to the rack rod without transmitting more motor torque than necessary by the supplied current.
It is transmitted to (5).

The control section (19) performs the steering assist suppression control by switching the steering assist force suppressing device (64) of the power assist device (56) to the steering assist suppressing state. In this case, the control unit (19) stops the power supply to the motor (57) while maintaining the power supply state to the clutch (59). As a result, when the steering wheel (6) is steered, the motor (57) and deceleration mechanism (5
The braking force by 8) is applied as steering reaction force.

Power assist device (56) by control unit (19)
The control of is similar to the case of FIG.

In the case of this embodiment, since the brake torque for applying the steering reaction force is added by using the motor (57) and the reduction mechanism (58) for applying the steering assist force, the brake torque is added. The structure can be simplified as compared with the case where the means for providing is separately provided. Also, the reduction mechanism
Since the worm gear used in (58) has a low reverse transmission efficiency, sufficient resistance can be obtained. Moreover, since the powder clutch (59) that does not lock is used, the motor (57) used as a brake is not damaged. It should be noted that when the steering assist suppression state is switched to, a larger electromotive force can be applied to the motor (57) to exert a larger braking force. Also, the motor (57)
Other known braking mechanisms may be provided at any suitable location driven by the.

In the above two embodiments, when the steering assist force suppressing devices (8) (64) of the power assist devices (7) (56) are switched to the steering assist suppressing state, the steering reaction force is applied. However, it is also possible to not apply the steering assist force corresponding to the steering force of the steering wheel (6) without applying the steering reaction force. Further, even when the steering reaction force is applied, the means is not limited to that in the above-mentioned embodiment.

FIG. 12 shows another embodiment of the power assist device.

When the steering assist suppression device (66) of the power assist device (65) is switched to the steering assist suppressed state, the rack rod (5) directly applies a steering reaction force to the power cylinder (30). Is given. In FIG.
At the end of the power cylinder (30), a reaction force applying member (67) using, for example, a piezoelectric element is arranged so as to sandwich the rack rod (5). The reaction force applying member (67) is controlled by the control unit (19), and thereby the steering assist state and the steering assist suppression state are switched. When switching to the steering assist state, the control section (19) does not apply the drive voltage to the reaction force applying member (67). Therefore, the reaction force applying member (67) is in a contracted state (non-operating state)
The rack rod (5) is held in a state where it can move freely, and steering assist is performed by the pressure oil supplied to the power cylinder (30). When switching to the steering assist suppression state, the control section (19) applies a drive voltage to the reaction force applying member (67). Therefore, the reaction force applying member (67) is held in the extended state (operating state), and the rack rod (5) is sandwiched to apply the steering reaction force.

FIG. 13 shows another embodiment of the power assist device.

When the steering assist suppression device (70) of the power assist device (69) is switched to the steering assist suppression state, the support yoke (71) causes the rack rod (5) to move the output shaft (2).
The steering reaction force is applied by pressing it strongly against the pinion (22a) of 2). In FIG. 13, a support yoke (71) for pressing the rack rod (5) against the pinion (22a) is slidably provided on the cylindrical portion (31a) of the housing (31). (72) is a cap screwed to the end of the cylindrical part (31a), (73) is a lock nut for fixing the cap (72), (74) is the cap (72) and the support yoke (71). And a compression coil spring disposed between the two. Between the cap (72) and the support yoke (71), a reaction force applying member (75) using, for example, a piezoelectric element is provided. The reaction force application member (75) is controlled by the control unit (19), and thereby the steering assist state and the steering assist suppression state are switched. When switching to the steering assist state, the control unit (19)
Do not apply drive voltage to (75). As a result, the reaction force imparting member (75) is held in a non-actuated state (contracted state), and the support yoke (71) properly applies the rack rod (5) to the pinion (22a) only by the elastic force of the spring (74). Press it with your power. Therefore, the pressing force of this support yoke (71) is the rack bar (5).
It does not resist the movement of the. When switching to the steering assist suppression state, the control section (19) applies a drive voltage to the reaction force applying member (75). As a result, the reaction force applying member (75) is held in the operating state (extended state), and the support yoke (71)
Push the rack bar (5) to the pinion (22a) with a strong force via. Therefore, a large resistance to the movement of the rack bar (5), that is, a steering reaction force is given.

FIG. 14 shows another embodiment of the power assist device.

The steering assist force suppressing device (78) of the power assist device (77) applies a steering reaction force to the power cylinder (30) when it is switched to the steering assist suppressing state. In FIG. 14, the rotary valve mechanism
An on-off valve (80) controlled by a signal from the control unit (19) is provided in the return oil passage (79) between the return oil port (29) of (26) and the oil tank (28). . When switching to the steering assist state, the control unit (19) holds the valve (80) in the fully opened state.
As a result, steering assist is performed by the pressure oil supplied from the rotary valve mechanism (26) to the power cylinder, just as in the case where the valve (80) is not provided. When switching to the steering assist suppression state, the control unit (19) holds the valve (80) in a fully closed state. As a result, the return oil passage (79) from the rotary valve mechanism (26) to the oil tank (28) is blocked, and the power cylinder
The back pressure in (30) becomes high, and a steering reaction force is applied to the movement of the rack bar (5).

In this case, the opening / closing valve (80) is changed to a variable throttle valve, and when the steering assist suppression state is switched, the throttle valve is throttled and an appropriate resistance is given to the return oil passage (79) so that the steering assist force is increased. An appropriate steering reaction force may be applied together with the decrease.

FIG. 15 shows another embodiment of the power assist device.

The steering assist force suppressing device (83) of the power assist device (82) also applies a steering reaction force at the power cylinder (30) when switched to the steering assist suppressing state. In FIG. 15, the power cylinder (30)
Oil passage (84a) between the left oil chamber (30a) and the cylinder port (46a) of the rotary valve mechanism (26) and the right oil chamber (30b) of the power cylinder (30) and the rotary valve mechanism (26). ) In the oil passage (84b) between the cylinder port (46b) and the control unit (1
On-off valves (85a) (85b) controlled by signals from 9) are provided respectively. When switching to the steering assist state, the control unit (19) maintains the valves (85a) and (85b) in the fully opened state. This allows the rotary valve mechanism (26) to move to the power cylinder (30) in exactly the same way as without the valves (85a) (85b).
Steering assistance is performed by the pressure oil supplied to. When switching to the steering assist suppression state, the control unit (19) is the valve (85a)
Hold (85b) fully closed. As a result, the oil is sealed in the power cylinder (30), the back pressure in the power cylinder (30) increases, and a steering reaction force is applied to the movement of the rack rod (5).

In this case as well, the opening / closing valves (85a) (85b) are changed to variable throttle valves, and when the steering assist suppression state is switched, the throttle valves are throttled and appropriate resistance is given to the oil passages (84a) (84b). Thus, the steering assist force may be reduced and an appropriate steering reaction force may be applied.

FIG. 16 shows another embodiment of the power assist device.

The steering assist force suppressing device (88) of the power assist device (87) does not apply the steering reaction force and does not apply the steering assist force when the steering assist suppressing state is switched to. It's just In FIG. 16, the oil chamber (30a) on the left side of the power cylinder (30) and the rotary valve mechanism (2
6) The oil passage (84a) between the cylinder port (46a), the oil chamber (30b) on the right side of the power cylinder (30) and the rotary valve mechanism.
The oil passage (84b) between the cylinder port (46b) of (26) is the oil passage.
An opening / closing valve (90) is provided which is connected by (89) and is controlled by a signal from the control section (19) in the communication oil passage (89). When switching to the steering assist state, the control unit (1
9) keeps the valve (90) fully closed. As a result, the steering assist is performed by the pressure oil supplied from the rotary valve mechanism (26) to the power cylinder (30), just as in the case where the communication oil passage (89) is not provided. When switching to the steering assist suppression state, the control unit (19) holds the valve (90) in the fully opened state. As a result, the left and right oil chambers (30a) (30b) of the power cylinder (30)
Are communicated with each other through the communication oil passage (89), and the steering assist force is not applied. In addition, the left and right oil chambers (30
Since the a) and (30b) are communicated with each other, the movement of the rack bar (5) is not hindered and the steering reaction force is not applied.

FIG. 17 shows another embodiment of the power assist device.

In FIG. 17, the left and right oil chambers (30a) (30b) of the power cylinder (30) are communicated with each other by an oil passage (92),
The communication oil passage (92) is provided with an opening / closing valve (93) controlled by a signal from the control section (19). Others are shown in FIG.
Is the same as

FIG. 18 shows another embodiment of the power assist device.

The steering assist force suppressing device (96) of the power assist device (95), when switched to the steering assist suppressing state, applies a steering reaction force in the direction opposite to the steering direction in the power cylinder (30) portion. It is to be given. In FIG. 18, there is a gap between the cylinder port (46a) of the rotary valve mechanism (26) and the left and right oil chambers (30a) (30b) of the power cylinder (30).
One directional control valve (97a) is provided, and the cylinder port (46b) of the rotary valve mechanism (26) and the power cylinder (30)
Another directional control valve (97b) is provided between the left and right oil chambers (30a) and (30b). When switching to the steering assist state, the control unit (19) shuts off one valve (97a) between the cylinder port (46a) and the oil chamber (30b) on the right side, and the cylinder port (46a) and the left side. The oil chamber (30a) of the cylinder is connected to the other, and the other valve (97b) is cut off between the cylinder port (46b) and the left oil chamber (30a), and the cylinder port (46b) is connected to the right side. Switch to the state where it communicates with the oil chamber (30b). As a result, the pressure oil supplied from the rotary valve mechanism (26) to the power cylinder (30) applies a force in the same direction as the steering direction to the rack rod (5) to assist steering. When switching to the steering assist suppression state,
The control unit (19) connects one valve (97a) to the cylinder port.
(46a) and the left oil chamber (30a) are cut off and
Switch the cylinder port (46a) to the oil chamber on the right (30b) so that it communicates with the other valve (97b).
(46b) and the oil chamber (30b) on the right side are cut off,
Switch to a state where the cylinder port (46b) communicates with the left oil chamber (30a). This allows the rotary valve mechanism (26)
A force in the opposite direction to the steering direction is applied to the rack rod (5) by the pressure oil supplied from the power cylinder (30) to the steering reaction force.

The steering assist suppression control by the control unit (19) is not limited to that in the above embodiment, but can be changed as appropriate.

For example, the steering angle before steering is stored in the steering angle storage unit (17), and when the steering assist suppression control is performed by the control unit (19), the stored steering angle before steering is stored. The power assist device may be controlled by the steering assist force suppressing device so that

Further, the traveling road recognition device of the front monitoring device (9)
The shape of the road ahead of the vehicle is recognized by (11), and when the steering assist suppression control is performed by the control unit (19), the steering assist force suppression device uses power assist to follow the recognized road. It is also possible to return to the steering assist state after controlling the device.

Further, the preceding vehicle traveling direction detecting device (12) of the front monitoring device (9) detects the traveling direction of the preceding vehicle relative to the own vehicle, and the control unit (19) performs steering assist suppression control. At this time, the steering assist force suppressing device may return to the steering assist state after controlling the power assist device so that the vehicle follows the preceding vehicle.

The power assist device (9
In the case of 5), by appropriately controlling the valves (97a) (97b), it is possible to steer in a desired direction regardless of the operation of the handle (6). In the above three cases, it is necessary to use, as the power assist device, the power assist device capable of steering in the desired direction by the steering assist force suppressing device.

Although the rack and pinion type power steering apparatus has been described in the above embodiments, the present invention can be applied to other types of power steering apparatuses such as a ball screw type.

Further, the present invention can also be applied to a vehicle steering system which is not provided with power assist, that is, a so-called manual steering system. In that case, the steering device includes a front monitoring means including a front obstacle detecting means for detecting an obstacle ahead of the vehicle, a side rear obstacle detecting means for detecting an obstacle behind the vehicle, and a front obstacle detecting means. Dangerous state determination means for determining whether the front side of the vehicle is in a dangerous state based on the output of the When the predetermined operation of the driver is performed, the front of the vehicle is not in a dangerous state, and the side rear of the vehicle is in a dangerous state, The steering mechanism is provided with a steering control means that applies a steering reaction force to the steering mechanism and does not apply a steering reaction force to the steering mechanism at other times.

19 to 21 show a steering shaft.
A ball screw (102) consisting of a male screw formed on the outer peripheral portion of the lower end of (100) and a nut member (101) connected to the male screw through a plurality of balls, formed on the outer peripheral portion of the nut member (101). Sector shaft (10
4), and an embodiment in which the present invention is applied to a manual steering device including a link (105) having one end connected to the sector shaft (104) and the other end connected to the wheel side.

FIG. 19 shows an example in which the steering reaction force applying device (106) is provided on the nut member (101), and FIG. 20 shows the steering reaction force applying device (106) provided at the end of the steering shaft (100). For example, FIG. 21 shows an example in which the steering reaction force applying device (106) is provided on the sector shaft (104).

The steering reaction force application device (106) is driven by, for example, a plunger (106a), a spring (106b) for urging the plunger (106a) toward the non-reaction force application side, and a signal from the control section (19). It is composed of an actuator (not shown) such as a piezoelectric element that biases the plunger (106a) toward the reaction force applying side during driving.

Others are the same as in the case of the above embodiment.

[0091]

According to the vehicle steering system of the first aspect of the present invention, as described above, the steering assist is not suppressed when it is unnecessary, and the steering assist is suppressed so that the front obstacle is prevented. There is no unavoidable thing.

A steering angle storage means for storing the steering angle before the start of steering is provided, and when the steering assist suppressing control is performed by the steering control means, the steering assist force suppressing means stores the stored steering angle before steering. If the power assist device is controlled so that, the danger can be avoided more reliably.

The front obstacle detecting means includes a traveling road recognizing means for recognizing the shape of the traveling road in front of the vehicle, and when the steering assist suppressing control is carried out by the steering control means, the steering assist force suppressing means recognizes it. If the steering assist state is set after the power assist device is controlled so that the vehicle follows the traveled road, the vehicle will not be off the traveled road and become more dangerous.

The front obstacle detecting means includes a preceding vehicle traveling direction detecting means for detecting the traveling direction of the preceding vehicle relative to the own vehicle, and when the steering assist suppressing control is performed by the steering control means, the steering assist force is detected. After the suppressing means controls the power assist device so that the vehicle follows the preceding vehicle,
As long as the vehicle is in the steering assist state, the vehicle will not be deviated from the traveling direction of the preceding vehicle to be in a more dangerous state.

According to the vehicle steering system of the sixth aspect of the present invention, as described above, the steering reaction force is not applied when it is not needed, and the steering reaction force is applied to prevent a front obstacle. There is no unavoidable thing.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a vehicle steering system showing an embodiment in which the invention is applied to a power steering system.

FIG. 2 is a configuration diagram of a main part of the steering device of FIG.

FIG. 3 is a schematic configuration diagram showing a main part of a power assist device of the steering device of FIG.

FIG. 4 is an enlarged cross-sectional view of a main part of FIG.

5 is a cross-sectional view taken along line VV of FIG.

6 is a cross-sectional view taken along the line VI-VI of FIG.

FIG. 7 is a flowchart showing an example of the operation of the control unit.

8 is a flow chart showing an example of a process of determining a dangerous state on the rear side of FIG.

FIG. 9 is a configuration diagram of a main part of a vehicle steering system showing another embodiment of the invention.

10 is a partially cutaway side view showing a main part of the power assist device of the steering device of FIG. 9. FIG.

11 is a cross-sectional view taken along line XI-XI of FIG.

FIG. 12 is a schematic configuration diagram showing another embodiment of the power assist device.

FIG. 13 is a schematic configuration diagram showing still another embodiment of the power assist device.

FIG. 14 is a schematic configuration diagram showing still another embodiment of the power assist device.

FIG. 15 is a schematic configuration diagram showing still another embodiment of the power assist device.

FIG. 16 is a schematic configuration diagram showing still another embodiment of the power assist device.

FIG. 17 is a schematic configuration diagram showing still another embodiment of the power assist device.

FIG. 18 is a schematic configuration diagram showing still another embodiment of the power assist device.

FIG. 19 is a schematic configuration diagram of a main part of a vehicle steering system showing an embodiment in which the invention is applied to a manual steering system.

FIG. 20 is a schematic configuration diagram of a main part of a vehicle steering system showing another embodiment in which the present invention is applied to a manual steering system.

FIG. 21 is a schematic configuration diagram of a main part of a vehicle steering system showing still another embodiment in which the present invention is applied to a manual steering system.

[Explanation of symbols]

(1) Steering device (2) Car body (6) Steering wheel (7) Power assist device (8) Steering assist force suppressing device (steering assist force suppressing means) (9) Front monitoring device (forward monitoring device) (10) Front obstacle Object detection device (front obstacle detection means) (11) Travel road detection device (travel road detection means) (12) Leading vehicle traveling direction detection device (leading vehicle traveling direction detection means) (13) Side rear obstacle detection device ( Side-rear obstacle detection means) (14) Steering angle detection device (16) Control unit (17) Steering angle storage section (steering angle storage means) (18) Danger state determination section (danger state determination means) (19) Steering control Part (Steering control means) (55) Steering device (56) Power assist device (64) Steering assist force suppressing device (steering assist force suppressing device) (65) Power assist device (66) Steering assist force suppressing device (steering assist force Suppressor) (69) Power assist device (70) Steering assist force suppressor (steering assist force suppressor) (77) Power assist Device (78) Steering assist force suppressing device (steering assist force suppressing means) (82) Power assist device (83) Steering assist force suppressing device (steering assist force suppressing device) (87) Power assist device (88) Steering assist force suppressing device Device (steering assist force suppressing means) (95) Power assist device (96) Steering assist force suppressing device (steering assist force suppressing means) (106) Steering reaction force applying device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location B62D 119: 00 (72) Inventor Tomohisa Kada 3-5-8 Minamisenba, Chuo-ku, Osaka Koyo Seiko Co., Ltd. (72) Inventor Shiro Nakano 3-5-8 Minamisenba, Chuo-ku, Osaka Koyo Seiko Co., Ltd. (72) Inventor Shigehisa Matsushita 3-5-8 Minamisenba, Chuo-ku, Osaka Koyo Seiko Co., Ltd. ( 72) Inventor Yoshihiro Goto Inside Koyo Seiko Co., Ltd. 3-5-8 Minamisenba, Chuo-ku, Osaka City (72) Yoshifumi Obata Inside 3-5-8 Minamisenba, Chuo-ku, Osaka City Koyo Seiko Co., Ltd.

Claims (6)

[Claims] 1. A steering device for a vehicle, comprising a power assist device for assisting a steering force of a steering wheel, wherein the steering device is provided in the power assist device and applies a steering assist force according to the steering force of the steering wheel. Steering assist force suppressing means for switching between an assisting state and a steering assist suppressing state in which no steering assisting force is applied according to the steering force of the steering wheel, and a front monitoring means including a front obstacle detecting means for detecting an obstacle in front of the vehicle. A side-rear obstacle detection means for detecting an obstacle behind the vehicle, and a side-rear obstacle detection means for determining whether or not the front of the vehicle is in a dangerous state based on an output from the front obstacle detection means. Dangerous state determination means for determining whether the vehicle's rear side is in a dangerous state based on the output from the Operation detecting means detect, and predetermined operation of the driver is performed, the front of the vehicle is not dangerous state, and when the side behind the vehicle is dangerous state,
A steering control unit is provided that performs steering assist suppression control that brings the steering assist force suppression unit into a steering assist suppression state for at least a predetermined time, and otherwise performs steering assist control that puts the steering assist force suppression unit into a steering assist state. A steering device for a vehicle, which is characterized in that 2. The vehicle steering system according to claim 1, wherein the steering assist force suppressing unit applies a steering reaction force to the power assist device when the steering assist suppressing control is performed by the steering control unit. 3. A steering angle storage means for storing the steering angle before the start of steering, wherein when the steering assist suppression control is performed by the steering control means, the steering assist force suppression means stores the stored steering angle before steering. The vehicle steering system according to claim 1, wherein the power assist device is controlled so as to have a steering angle. 4. The front monitoring means comprises a traveling road recognition means for recognizing the shape of a traveling road in front of the vehicle, and when the steering assist suppressing control is carried out by the steering control means, the steering assist force suppressing means recognizes it. The vehicle steering system according to claim 1, wherein the steering assist state is established after the power assist system is controlled so that the vehicle follows the traveled road. 5. The front monitoring means includes a preceding vehicle traveling direction detecting means for detecting a traveling direction of the preceding vehicle relative to the own vehicle, and when the steering assist suppressing control is performed by the steering control means, a steering assist force is provided. 2. The vehicle steering system according to claim 1, wherein the suppressing means controls the power assist device so that the vehicle follows the preceding vehicle and then enters the steering assist state. 6. A front monitoring means including a front obstacle detecting means for detecting an obstacle ahead of the vehicle, a side rear obstacle detecting means for detecting an obstacle behind the vehicle, and an output from the front obstacle detecting means. Dangerous state determination means that determines whether the front side of the vehicle is in a dangerous state based on the When the predetermined operation of the driver is performed and the front of the vehicle is not in a dangerous state and the side rear of the vehicle is in a dangerous state,
A steering apparatus for a vehicle, comprising: steering control means for applying a steering reaction force to the steering mechanism and not applying a steering reaction force to the steering mechanism at other times.