JP2003146229A - Vehicular steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable steering during the occurrence of failure without building a double system comprising a steering angle sensor for detecting the operating position of a steering means and a reaction motor for applying false reaction to the steering means. SOLUTION: Detection values for the rotating angle sensor 24 provided on the reaction motor M3 for applying reaction to a steering wheel 2 as the steering means are previously accumulated for calculating the steering angle of the steering wheel 2. When a failure occurs in the steering angle sensor 23, a steering motor M1 is controlled to apply steering force to a steering mechanism 1 in accordance with the calculated steering angle. An electromagnetic clutch 22 is mounted in a transmission system between the reaction motor M3 and the steering wheel 2. When the failure occurs in the reaction motor M3 , the electromagnetic clutch 22 is cut off to permit the operation of the steering wheel 2.

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 for steering a vehicle in response to an operation of a steering means such as a steering wheel performed by a driver.

[0002]

2. Description of the Related Art Steering of a vehicle is performed by operating a steering means (generally, a steering wheel rotating operation) performed by a driver inside a passenger compartment, and manipulating a steering wheel (generally a front wheel). This is done by telling the steering mechanism that is arranged outside the passenger compartment for the purpose of direction.

As a steering device for performing such steering, in recent years, the steering means inside the passenger compartment is mechanically separated from the steering mechanism outside the passenger compartment, and a part of the steering mechanism is provided. An actuator for steering is attached, the operation of the steering actuator is controlled according to the operation of the steering means, and a separation type steering device configured to apply a steering force to the steering mechanism to perform steering, for example, Japanese Patent Laid-Open No. 10-
It is proposed in the publication No. 218000.

In this steering system, the correspondence between the operation amount of the steering means and the operation amount of the steering actuator can be set without any mechanical restriction.
It has the advantage of being able to flexibly respond to change control of the steering characteristics according to the traveling state such as the presence or absence of acceleration / deceleration, and also does not require a connecting member for connecting the steering means and the steering mechanism. It has many advantages that cannot be obtained with a general steering system, such as the fact that there is no restriction on the configuration and arrangement, and the flexibility of the layout inside the vehicle interior is increased, and it is useful for the development of automobile technology. Is being watched as.

As the steering actuator,
An electric motor (steering motor) is used in consideration of easiness of control for changing steering characteristics. The steering motor detects the angle detected by a steering angle sensor for detecting the operating position of the steering means and the operation of the steering mechanism. Feedback control is performed based on the deviation from the detected angle of the actual steering angle sensor that detects the position. Further, a reaction force motor is attached to the steering means, and this reaction force motor is drive-controlled based on the detection result of the reaction force sensor that detects the steering reaction force applied to the steering mechanism in association with steering,
A pseudo reaction force is applied to the steering means so that a steering feeling equivalent to that of the non-separable steering device can be obtained.

[0006]

In the separated type steering apparatus constructed as described above, the steering angle sensor attached to the steering means is an important sensor used for controlling the steering motor. When the angle sensor falls into the fail state, there is a risk that steering different from the driver's intention will be performed.

Therefore, in the prior art, the above-mentioned Japanese Patent Laid-Open No. 10-21
As disclosed in Japanese Patent No. 8000, two steering angle sensors are provided, and the presence or absence of these failures is sequentially determined,
If one is determined to be in the fail state, the control of the steering motor is continued based on the detection result of the other so as not to hinder the steering. In addition, there is a problem that the structure of the steering means becomes complicated and that the cost of the device increases.

On the other hand, when the reaction force motor for applying the pseudo reaction force to the steering means falls into a fail state such as motor lock, the existence of the reaction force motor hinders the operation of the steering means,
There is a problem that steering cannot be performed as the driver intends.

This problem can be solved by providing two reaction force motors and using the other one when one fails, as in the case of the steering angle sensor fail countermeasure, but the structure of the steering means becomes more complicated, and the device This will lead to a further increase in costs.

The present invention has been made in view of such circumstances, and a steering angle sensor for detecting the operation position of the steering means or a reaction force motor for applying a pseudo reaction force to the steering means does not have to be a double system. An object of the present invention is to provide a vehicle steering system capable of steering when these failures occur.

[0011]

A vehicle steering system according to a first aspect of the present invention includes a steering angle sensor for detecting an operating position of a steering means and a steering mechanism mechanically separated from the steering means. With a reaction force sensor that detects the steering reaction force applied,
The steering actuator attached to the steering mechanism is controlled based on the detection result of the steering angle sensor to perform steering corresponding to the operation of the steering means, and the steering means is attached to the steering means based on the detection result of the reaction force sensor. In a vehicle steering system in which a reaction force motor is controlled to apply a pseudo reaction force to the steering means, a rotation angle sensor that detects a rotation angle of the reaction force motor and a detection value of the rotation angle sensor are accumulated. A steering angle calculation means for calculating an operation position of the steering means,
Sensor fail determining means for determining whether or not the steering angle sensor has failed, and control means for controlling the steering actuator based on the calculation result of the steering angle calculating means when the sensor fail determining means makes a fail determination. It is characterized by including.

In the present invention, the fact that the reaction force motor for applying the pseudo reaction force to the steering means rotates in response to the operation of the steering means is used, and the reaction force motor is provided with a rotation angle sensor for detecting the rotation angle. The operation position of the steering means is calculated by sequentially accumulating the detection values of the rotation angle sensor, and when the steering angle sensor fails, the operation position of the steering means calculated from the detection value of the rotation angle sensor is used. The steering actuator is controlled so that steering can be performed according to the driver's intention. When a brushless motor is used as the reaction force motor, the rotation angle sensor is indispensable for controlling the motor, and it is not necessary to provide a dedicated sensor as a countermeasure against fail. When a steering wheel is used as the steering means, the operation angle of the steering wheel calculated by accumulating the detection values of the rotation angle sensor is different from the operation angle detected by the steering angle sensor at a position different from this. The deviation can be used to calculate the steering torque applied to the steering wheel necessary for controlling the reaction force motor.

A vehicle steering system according to a second aspect of the present invention includes a steering angle sensor for detecting the operating position of the steering means,
A reaction force sensor for detecting a steering reaction force applied to a steering mechanism mechanically separated from the steering means, and controlling a steering actuator attached to the steering mechanism based on a detection result of the steering angle sensor, For a vehicle in which steering corresponding to the operation of the steering means is performed, and a reaction force motor attached to the steering means is controlled based on the detection result of the reaction force sensor to apply a pseudo reaction force to the steering means. In the steering device, a clutch interposed in a transmission system from the reaction force motor to the steering means, a motor fail determination means for determining whether or not the reaction force motor fails, and a failure determination by the motor failure determination means. And a clutch control means for controlling the disengagement of the clutch when the clutch is made.

In the present invention, a clutch is arranged in the transmission system from the reaction force motor for applying the pseudo reaction force to the steering means to the steering means, and when the reaction force motor fails, the clutch is disengaged to cause a failure state. The reaction force motor is separated from the steering means so as not to hinder the operation of the steering means, and the steering means under the non-application of the reaction force enables the steering according to the intention of the driver.

A vehicle steering system according to a third aspect of the present invention includes a steering angle sensor for detecting the operation position of the steering means,
A reaction force sensor for detecting a steering reaction force applied to a steering mechanism mechanically separated from the steering means, and controlling a steering actuator attached to the steering mechanism based on a detection result of the steering angle sensor, For a vehicle in which steering corresponding to the operation of the steering means is performed, and a reaction force motor attached to the steering means is controlled based on the detection result of the reaction force sensor to apply a pseudo reaction force to the steering means. In the steering device, a second steering means formed separately from the steering means, a motor fail determination means for determining whether or not the reaction force motor has failed, and a failure determination made by the motor failure determination means A control hand that prohibits the control of the steering actuator based on the detection result of the steering angle sensor and controls the steering actuator according to the operation of the second steering means. Characterized in that it comprises and.

In the present invention, the second steering means is provided separately from the original steering means, and when the reaction motor fails to apply a pseudo reaction force to the steering means, the operation is obstructed by the reaction motor. The control of the steering actuator based on the detection result of the operating position of the steering means is prohibited, and the steering actuator is controlled according to the operation of the second steering means to enable the steering according to the intention of the driver. The second steering means may be any means having a simple configuration capable of indicating at least the steering direction, and an appropriate configuration such as a lever, a handgrip or a switch can be used.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings showing the embodiments thereof. FIG. 1 is a block diagram showing the overall configuration of a vehicle steering system according to the present invention.

This steering system includes a steering mechanism 1 for causing a pair of steering wheels 10, 10 arranged on the left and right of the vehicle body to perform a steering operation, and a mechanical separation from the steering mechanism 1. And a steering wheel (steering means) 2 arranged in the same manner, and a control operation described later in order to operate the steering mechanism 1 in response to the operation of the steering wheel 2 and to apply a steering reaction force to the steering wheel 2. And a steering control section 3 for performing the above.

The steering mechanism 1 is a well-known rack and pinion type steering mechanism, and is used for steering both ends of a rack shaft 11 extending in the left-right direction of the vehicle body and moving in the axial direction. Wheel
10 and 10 knuckle arms 12 and 12 with different tie rods 13 and
The knuckle arms 12 and 12 are pushed and pulled through the tie rods 13 and 13 by moving the rack shaft 11 in both directions, and the wheels 10 and 10 are steered left and right.

In order to perform this steering, a steering motor M ₁ (obliquely crossed with a tubular rack housing H ₁ which supports the rack shaft 11 movably in the axial direction, is provided outside the middle portion thereof. Brushless motor) is installed. The output shaft of the steering motor M ₁ extends inside the rack housing H ₁ and is configured to be transmitted to the middle of the rack shaft 11 via a motion conversion mechanism such as a ball screw mechanism. Therefore,
The rotation of the steering motor M ₁ is converted by the motion conversion mechanism into movement of the rack shaft 11 in the axial direction, and the above-described steering is performed according to this movement.

An auxiliary steering motor M ₂ driven when the steering motor M ₁ fails is attached to the outside of the pinion housing H ₂ which is continuously provided so as to intersect with a part of the rack housing H ₁ . . A pinion shaft 14 is supported inside the pinion housing H ₂ so as to be rotatable around its axis. In the lower half of the pinion shaft 14 where only the protruding end of the pinion housing H _{2 to} the upper part is shown,
A pinion (not shown) is integrally formed and meshes with the rack teeth formed at the corresponding portion of the rack shaft 11 at the intersection with the rack housing H ₁ .

The output shaft of the auxiliary steering motor M ₂ is provided inside the pinion housing H ₂ at a position away from the axis of the pinion shaft 14 and extends in a direction substantially orthogonal to the axis of the pinion shaft 14 to form a worm gear. It is configured to be transmitted to the middle of the pinion shaft 14 via a speed reducing mechanism such as a mechanism. Thus, the rotation of the auxiliary steering motor M ₂ is transmitted to the pinion shaft 14 under deceleration by the reduction mechanism, and the rotation of the pinion shaft 14 is
At the meshing portion of the pinion and the rack teeth, the rack shaft 11
Is converted into movement in the axial direction, and the above-described steering is performed according to this movement.

An operation command from the steering control section 3 is given to the steering motor M ₁ and the auxiliary steering motor M ₂ via separate drive circuits (not shown), and both steering motors M are operated in accordance with the operation commands. ₁ , ₁ and M ₂ are individually driven and controlled.

The actual steering angle θ ₀ of the steering wheels 10, 10 steered as described above in response to this drive is, for example, the rack shaft 11
Is detected by the actual steering angle sensor 15 configured to detect the displacement of the connection portion between the tie rod 13 and the one side tie rod 13, and the steering control unit 3
Is given to. As shown in FIG. 1, the actual steering angle sensor 15 has a detection cylinder interposed between the connecting portion and the outside of the rack housing H ₁ , and detects the displacement through the amount of advance / retreat of the detection cylinder. It can be configured to.

The steering motor M ₁ is further provided with a rotation angle sensor 16 for detecting the rotation angle of the steering motor M ₁ . The output of the rotation angle sensor 16 is given to the steering control unit 3 and is used to adjust the phase of the drive current of the steering motor M ₁ and, as will be described later, substitutes when the actual steering angle sensor 15 fails. It is used to calculate the actual steering angle used. Such a rotation angle sensor 16 can be configured by a known resolver, for example.

The tie rods 13, 13 on both sides are provided with tie rod axial force sensors (reaction force sensors) 17, 17 for detecting the axial force (tensile force or compressive force) acting on these tie rods. The detection results are given to the steering control unit 3 as a signal indicating a steering reaction force actually applied to the steering wheels 10 and 10 in association with steering. The tie rod axial force sensors 17, 17 are configured such that, for example, a strain gauge is attached to the surface of the tie rods 13, 13 and the steering reaction force is detected through the strain generated in each of the tie rods 13, 13 as a medium. Can be

The steering wheel 2 which is mechanically separated from the steering mechanism 1 configured as described above is shown in FIG.
As schematically shown therein, it is supported by an appropriate portion of a vehicle body (not shown) via a column housing H ₃ which rotatably holds a column shaft 20 which is its rotation shaft, and the other side of the column housing H ₃ A reaction force motor M ₃ (brushless motor) is attached to the. The output shaft of the reaction force motor M ₃ is coaxially extended inside the column housing H ₃ .
The column shaft 20 via the reduction gear 21 and the electromagnetic clutch 22.
Are linked to. With this configuration, the rotational force of the reaction force motor M ₃ is transmitted to the column shaft 20 under deceleration by the speed reducer 21 when the electromagnetic clutch 22 is engaged, and the steering wheel attached to the upper end of the column shaft 20. 2, a reaction force opposite to the operation direction is applied.

The reaction force applied to the steering wheel 2 by the reaction force motor M ₃ is applied to the steering wheels 10 and 10 in association with the steering operation.
The steering reaction force actually applied to the steering wheel 2 is artificially applied to the steering wheel 2 so that the driver can experience it. The reaction command from the steering control unit 3 to the reaction force motor M ₃ is shown in the figure. It is given via a drive circuit and is driven according to this operation command. The operation command of the steering control unit 3 is also given to the electromagnetic clutch 22, and the electromagnetic clutch 22 is disengaged in accordance with the operation command from the steering control unit 3 so that the reaction force motor M ₃ is operated from the steering wheel 2. It is designed so that it can be disconnected.

The steering angle θ ₁ of the steering wheel 2 operated against such a pseudo reaction force is detected by a steering angle sensor 23 formed in the middle of the column shaft 20 and given to the steering control section 3. ing. The steering angle sensor 23 is, for example,
It can be configured by a potentiometer that changes the output according to the displacement from the steering angle midpoint position.

The reaction force motor M ₃ is further provided with a rotation angle sensor 24 for detecting the rotation angle of the reaction force motor M ₃ . The output of the rotation angle sensor 24 is given to the steering control unit 3 and is used to adjust the phase of the drive current of the reaction force motor M ₃ and, as described later, the steering wheel to be used instead when the steering angle sensor 23 fails. Used to calculate the angle θ ₂ . The steering angle θ ₂ calculated as described above is used to calculate the steering torque applied to the steering wheel 2 based on the deviation from the steering angle θ ₁ detected by the steering angle sensor 23. Steering torque thus calculated, the reaction motor M ₃ is as a feedback signal of the reaction force generated is utilized to the fail determination of the reaction force motor M _3. Such a rotation angle sensor 24 can be configured by a known resolver, like the rotation angle sensor 16 attached to the steering motor M ₁ .

As described above, the steering control section 3 includes the steering mechanism 1
The steering state actually occurring on the side of the
15, the rotation angle sensor 16 and the tie rod axial force sensors 17, 17, and the operation state of the steering wheel 2 as steering means is provided as the inputs from the steering angle sensor 23 and the rotation angle sensor 24. ing. Further, various signals such as vehicle speed, yaw rate, lateral acceleration and the like indicating the traveling state of the vehicle detected by the traveling state sensor 4 are given to the input side of the steering control section 3.

On the other hand, the output of the steering control unit 3 applies a reaction force to the steering wheel 2 and the steering motor M ₁ or the auxiliary steering motor M ₂ for causing the steering mechanism 1 to perform the steering operation as described above. reaction force applied to the motor M _3, further provided to the electromagnetic clutch 22 arranged on the power transmission system from the reaction motor M ₃ to the steering wheel 2 to be.

FIG. 2 shows a steering motor M operated by the steering control unit 3.
₃ is a flowchart showing the control contents of ₁ . When it is determined that the steering motor M ₁ has fallen into a fail state such as motor lock, the auxiliary steering motor M ₂ is operated by the auxiliary steering motor M _2.
1 and switching to drive, is provided with in order to prevent steering inability generation, the control operation for the auxiliary steering motor M ₂ is performed exactly as in the following control operation for the steering motor M _1. The fail determination of the steering motor M ₁ may be performed by using a fail determination method that is normally used in various motors, such as monitoring a change in driving current of the steering motor M ₁ with time.

The steering control section 3 starts its operation in response to an ON operation of a key switch for starting the engine, and outputs the outputs of the steering angle sensor 23 and the rotation angle sensor 24 connected to the input side in a predetermined sampling cycle. At (step 1), the output of the running condition sensor 4 is also taken in (step 2).

Next, the steering control unit 3 calculates the steering angle θ ₁ of the steering wheel 2 using the output of the steering angle sensor 23 (step 3), and also uses the output of the rotation angle sensor 24 to calculate the steering angle θ ₂ . Calculate (step 4).

As described above, the output of the steering angle sensor 23 corresponds to the displacement from the steering angle midpoint position, and the steering angle θ ₁
Is calculated by multiplying this output by a predetermined gain.
The output of the rotation angle sensor 24 indicates the rotation angle of the reaction force motor M _{3 at} the time of sampling, and the calculation of the steering angle θ ₂ is performed by sequentially outputting the output of the rotation angle sensor 24 for each sampling cycle. The results are accumulated, and the obtained result is multiplied by a predetermined gain corresponding to the reduction ratio of the reduction gear device 21.

Next, the steering control section 3 determines whether or not the steering angle sensor 23 is in a fail state (step 5). When it is determined that the steering angle sensor 23 is normal, the steering angle θ is determined. _When the steering angle sensor 23 is determined to be in the fail state, the target steering angle θ that is the target value for steering is calculated using ₁ and the target steering angle θ ₂ is used to determine the target steering angle θ _2. The angle θ is calculated (step 7), and at the same time, an operation command is issued to an alarm means (not shown) connected to the output side to output an alarm (step 8).

By the operation of the steering control unit 3 as described above, it is constantly determined whether or not the steering angle sensor 23 is in the fail state, and when it is determined that the steering angle sensor 23 is in the fail state, the output of the steering angle sensor 23 is output. The use of the steering angle θ ₁ calculated using is stopped, and the target steering angle θ is obtained using the steering angle θ ₂ calculated using the output of the rotation angle sensor 24. Therefore, when the steering angle sensor 23 fails, the target steering angle θ is calculated based on an erroneous detection value, and it is possible to prevent steering that does not follow the driver's intention to operate the steering wheel 2. The rotation angle sensor 24 includes a reaction force motor M ₃
It is a sensor originally required for the control of, and a dedicated sensor for fail-safe is not required, preventing the configuration from becoming complicated,
It can contribute to the reduction of the device cost.

However, the target steering angle θ using the steering angle θ ₂
Is calculated in order to prevent the steering angle sensor 23, which is the original detecting means, from being unable to steer when the steering angle sensor 23 fails. The warning output in step 8 is the steering angle sensor.
This is performed to notify the driver that 23 is in a fail state and that normal steering may not be performed, for example, to prompt an emergency procedure such as bringing the running vehicle closer to the road shoulder and stopping.

In the fail judgment of the steering angle sensor 23 in step 5, the output history of the steering angle sensor 23 is referred to, and for example, the difference in output at each sampling time point is out of the preset normal range. Alternatively, it can be performed on the condition that the difference from the output history of the rotation angle sensor 24 is excessively large.

The calculation of the target rudder angle θ in step 6 or step 7 is carried out by using the vehicle speed, yaw rate, longitudinal acceleration, etc.
This is done by multiplying the steering angle θ ₁ or θ ₂ by a correction coefficient determined for each of the traveling states that affect the steering detected by the traveling state sensor 4. For example,
The correction coefficient for the vehicle speed is set to be small during high-speed traveling where the vehicle speed exceeds a predetermined speed, and to increase proportionally to the decrease in the vehicle speed during low-speed traveling where the vehicle speed is less than the predetermined speed. Further, the correction coefficient for the yaw rate, which indicates the turning state of the vehicle, is set to decrease as the yaw rate increases. By performing these corrections, the target steering angle θ calculated in step 6 or step 7 is smaller than the steering angle θ ₁ or θ ₂ indicating the operation position of the steering wheel 2 during high-speed traveling and low-speed traveling. The steering characteristic adapts to the running state of the vehicle, which gradually changes and becomes larger during turning, and becomes sharper during turning.

After calculating the target rudder angle θ as described above, the steering control section 3 takes in the output of the actual rudder angle sensor 15 connected to the input side (step 9) and uses this output to operate the steering mechanism 1 The actual steering angle θ ₀ realized in
10), deviation from the target steering angle θ (steering angle deviation Δθ = θ−θ
₀ ) is calculated (step 11), and the steering motor M ₁ is drive-controlled to flow a drive current corresponding to the steering angle deviation Δθ (step 12). The above control operation is repeated until the key switch is turned off.

During this period, the output of the rotation angle sensor 16 attached to the steering motor M ₁ is used to calculate the actual steering angle θ ₀ which is used as an alternative when the actual steering angle sensor 15 fails. The rotation angle sensor 16 is also a sensor originally necessary for controlling the steering motor M ₁ , and can perform fail-safe operation without using the actual steering angle sensor 15 as a dual system. Further, the drive current of the steering motor M ₁ is determined as a value corresponding to the steering angle deviation Δθ on a drive current map prepared for each vehicle speed, for example.

The steering control unit 3 uses the steering motor M as described above.
_In parallel with the control of ₁ , the control operation of the reaction force motor M ₃ and the electromagnetic clutch 22 attached to the steering means 2 is performed. Figure 3
Reaction force motor M ₃ and electromagnetic clutch 22 by the steering control unit 3
3 is a flowchart showing the control contents of FIG.

As described above, the steering control section 3 which starts its operation in response to the ON operation of the key switch first takes in the outputs of the tie rod axial force sensors 17, 17 connected to the input side (step 21), and outputs this output. The actual steering reaction force F ₀ actually applied to the steering mechanism 1 is calculated by using (step 22).

Next, the steering control section 3 judges whether or not the reaction force motor M ₃ to be controlled is in a fail state (step 23), and the reaction force motor M ₃ is normal and can be controlled. If it is determined, the steering reaction force F to be applied to the steering wheel 2 is calculated using the actual steering reaction force F ₀ (step 24), and the reaction force is generated in order to generate the driving torque according to the steering reaction force F. Drive control of the motor M ₃ (step
twenty five).

The steering reaction force F is calculated by multiplying the actual steering reaction force F ₀ detected by the tie rod axial force sensors 17, 17 by a predetermined coefficient. This coefficient can be changed according to the traveling state detected by the traveling state sensor 4, such as vehicle speed, yaw rate, and longitudinal acceleration. For example, the detected values of the vehicle speed and the yaw rate are used to increase and correct the coefficient according to these increases, and the detected value of the longitudinal acceleration increases and corrects the coefficient according to the degree when the deceleration state is detected. It is used.

By performing such a correction, the steering wheel 2 becomes heavier as the vehicle speed increases and becomes lighter as the vehicle speed decreases, improving the straight-line stability during high-speed traveling, and during low-speed traveling or stopping. A reduction in operating force over time is also achieved. Further, the steering wheel 2 becomes heavier as the turning degree becomes larger, and it is possible to give a weight suitable for the turning state. Furthermore, the steering wheel 2 becomes heavier during deceleration, which allows the driver to experience an increase in front wheel load due to deceleration.

On the other hand, in step 23, the reaction force motor M ₃
Is determined to be uncontrollable, the steering control unit 3 issues an operation command to the electromagnetic clutch 22 on the output side to cause the electromagnetic clutch 22 to be disengaged (step 26) and not shown. Issue an operation command to the alarm means,
An alarm is output (step 27).

The electromagnetic clutch 22 is interposed in the transmission system from the reaction force motor M ₃ to the steering wheel 2. When the electromagnetic clutch 22 is disengaged, the steering wheel 2 is disconnected from the reaction force motor M _3. . Therefore, by the above-described operation of the steering control unit 3, there is no fear that the reaction force motor M ₃ in a fail state such as motor lock will hinder the operation of the steering wheel 2, and the occurrence of steering failure can be avoided.

However, since the steering wheel 2 is operated with the electromagnetic clutch 22 disengaged, no steering reaction force is applied, so that the steering is equivalent to normal steering with the electromagnetic clutch 22 engaged. No steering feel is obtained. Step
The alarm output in 27 notifies the driver that the reaction force motor M ₃ is in a fail state and the steering feeling is changed, and prompts an emergency procedure, for example, to bring the running vehicle closer to the road shoulder and stop it. Will be done.

The determination of the failure of the reaction force motor M ₃ in step 23 is made by, for example, detecting the steering torque applied to the column shaft 20 of the steering wheel 2 while the reaction force motor M ₃ is rotating, and determining the steering torque. This can be done by comparing with the reaction force F. Here, the steering torque is calculated based on the deviations of the steering angles θ ₁ and θ ₂ obtained at two different positions of the column shaft 20 using the outputs of the steering angle sensor 23 and the rotation angle sensor 24 as described above. Therefore, it is not necessary to use a dedicated torque sensor. In addition, the fail determination may be performed by using a fail determination method that is normally performed in various motors, such as monitoring a change over time of the drive current of the reaction force motor M ₃ .

FIG. 4 is a block diagram showing another embodiment of the vehicle steering system according to the present invention. The vehicle steering system shown in this figure includes a second steering means 5 that is configured separately from the steering wheel 2, and a clutch is provided in a transmission system from the reaction force motor M ₃ to the steering wheel 2. Except for the fact that it is not mounted, it has the same configuration as the vehicle steering system shown in FIG. 1, and corresponding parts are assigned the same reference numerals and explanations thereof are omitted.

When it becomes difficult to operate the steering wheel 2, which is the first steering means, due to the failure of the reaction force motor M ₃ , the second steering means 5 allows the steering wheel 2 to be urgently steered. Placed near the
It is connected to the input side of the steering control unit 3.

When it is determined in step 23 of FIG. 3 that the reaction force motor M ₃ is in the fail state, the steering control section 3 prohibits the control of the steering motor M _{1 according to} the flowchart of FIG. Instead of the outputs of the steering angle sensor 23 and the rotation angle sensor 24 indicating the operation state,
The output of the second steering means 5 is fetched. The second steering means 5 may have a simple structure such as a lever, a handgrip, and a switch that can specify at least the steering direction. The steering control unit 3 outputs the steering direction according to the output of the second steering means 5. Is recognized, the steering motor M ₁ is continuously driven in the same direction.

In this embodiment, the reaction force motor M
_When the steering wheel ₃ is in a fail state and the operation of the steering wheel 2 is obstructed, the second steering means 5 is operated in place of the steering wheel 2 so that the steering controller 3 responds to the operation. An emergency steering can be performed by the operation. The operation of the second steering means 5 is a simple operation such that the steering direction is designated by the lever, handgrip, switch, etc., but the driver moves the running vehicle to the road shoulder and stops it. Emergency treatment is possible. Also in this embodiment, it is desirable to output an alarm according to the failure judgment of the reaction force motor M ₃ so as to prompt the driver to operate the second steering means 5.

[0057]

As described in detail above, in the vehicle steering system according to the first aspect of the present invention, when the steering angle sensor attached to the steering means fails, the rotation attached to the reaction force motor that applies the steering reaction force to the steering means. The steering motor is controlled based on the detection result of the angle sensor, and the steering according to the driver's intention can be continued, and a dedicated sensor for this is not required, which simplifies the configuration and reduces the product cost. Can be reduced.

Further, in the vehicle steering system according to the second aspect of the present invention, when the reaction force motor for applying the steering reaction force to the steering means fails, the clutch interposed in the transmission system from the reaction force motor to the steering means is disengaged. The reaction force motor in the failed state is disconnected, the operation of the steering means is not obstructed, and steering according to the driver's intention is possible.

Further, in the vehicle steering system according to the third aspect of the present invention, when the reaction force motor for applying the steering reaction force to the steering means fails, the second steering means is provided separately from the steering means provided with the reaction force motor. The present invention has an excellent effect such that an emergency steering can be performed according to the intention of the driver by operating the steering means.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of a vehicle steering system according to the present invention.

FIG. 2 is a flowchart showing a control content of a steering motor by a steering control unit.

FIG. 3 is a flowchart showing control contents of a reaction force motor and an electromagnetic clutch by a steering control unit.

FIG. 4 is a block diagram showing another embodiment of the vehicle steering system according to the present invention.

[Explanation of symbols]

1 Steering Mechanism 2 Steering Wheel (Steering Means) 3 Steering Control Unit 5 Second Steering Means 11 Rack Shaft 15 Actual Steering Angle Sensor 16 Rotation Angle Sensor 17 Tie Rod Axial Force Sensor (Reaction Force Sensor) 22 Electromagnetic Clutch 23 Steering Angle Sensor 24 Rotation angle sensor M ₁ Steering motor (steering actuator) M ₂ Auxiliary steering motor (steering actuator) M ₃ Reaction motor

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kenji Azuma             3-5-8 Minamisenba, Chuo-ku, Osaka-shi, Osaka               Koyo Seiko Co., Ltd. (72) Inventor Masaya Segawa             3-5-8 Minamisenba, Chuo-ku, Osaka-shi, Osaka               Koyo Seiko Co., Ltd. (72) Inventor Tomoho Kada             3-5-8 Minamisenba, Chuo-ku, Osaka-shi, Osaka               Koyo Seiko Co., Ltd. F-term (reference) 3D032 CC33 DA02 DA03 EB12                 3D033 CA03 CA13 CA17 CA18 CA31

Claims (3)

[Claims] 1. A steering angle sensor comprising: a steering angle sensor for detecting an operation position of a steering means; and a reaction force sensor for detecting a steering reaction force applied to a steering mechanism mechanically separated from the steering means. The steering actuator attached to the steering mechanism is controlled based on the detection result of the steering mechanism to perform steering corresponding to the operation of the steering means, and the reaction force motor attached to the steering means is detected based on the detection result of the reaction force sensor. Control the
In a vehicle steering system configured to apply a pseudo reaction force to the steering means, a rotation angle sensor for detecting a rotation angle of the reaction force motor, and an operation position of the steering means by accumulating detection values of the rotation angle sensor. Steering angle calculation means, a sensor fail determination means for determining whether or not the steering angle sensor has failed, and when the sensor failure determination means determines a failure, based on the calculation result of the steering angle calculation means A vehicle steering system comprising: a control unit that controls the steering actuator. 2. A steering angle sensor comprising: a steering angle sensor for detecting an operation position of the steering means; and a reaction force sensor for detecting a steering reaction force applied to a steering mechanism mechanically separated from the steering means. The steering actuator attached to the steering mechanism is controlled based on the detection result of the steering mechanism to perform steering corresponding to the operation of the steering means, and the reaction force motor attached to the steering means is detected based on the detection result of the reaction force sensor. Control the
In a vehicle steering system configured to apply a pseudo reaction force to the steering means, a clutch interposed in a transmission system from the reaction force motor to the steering means, and a motor for determining presence / absence of a failure of the reaction force motor. A vehicle steering system comprising: a fail determination means; and a clutch control means for controlling the disengagement of the clutch when the motor fail determination means makes a fail determination. 3. A steering angle sensor comprising: a steering angle sensor for detecting an operation position of the steering means; and a reaction force sensor for detecting a steering reaction force applied to a steering mechanism mechanically separated from the steering means. The steering actuator attached to the steering mechanism is controlled based on the detection result of the steering mechanism to perform steering corresponding to the operation of the steering means, and the reaction force motor attached to the steering means is detected based on the detection result of the reaction force sensor. Control the
A vehicle steering system configured to apply a pseudo reaction force to the steering means, a second steering means configured separately from the steering means, and a motor fail determination means for determining whether or not the reaction force motor has failed. And a control for prohibiting the control of the steering actuator based on the detection result of the steering angle sensor and controlling the steering actuator according to the operation of the second steering means when the motor failure determination means makes a failure determination. A vehicle steering apparatus comprising: