JPH0692251A - Motor driven power steering gear - Google Patents

Abstract

PURPOSE:To automatically return wheels to a neutral position in parking on a horizontal road surface and maintain the parking condition of the wheels in parking on a slope road under the condition of the wheels having a steered angle given purposely. CONSTITUTION:A motor power steering gear has a motor M1 for driving a steering linkage member S, a steering condition detecting device M2 and a controller M3 for controlling the motor according to the detected steering condition. Also, it has a returning device M5 for controlling the motor to return the steering linkage member to the neutral position when the parking condition of a vehicle is detected by a parking detecting device M4 and a prohibiting device M7 for prohibiting the control of the motor for returning the steering linkage member to the neutral position by the returning device when a parking road surface is judged to be on a slope road, by a slope road judging device M6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering device for vehicles such as automobiles, and more particularly to an electric power steering device.

[0002]

2. Description of the Related Art Electric power steering systems for vehicles such as automobiles generally have a motor for driving a steering member such as a rack bar via a steering gear box, and a control device for controlling the rotation of the motor. The control device is configured to generate a required steering assist force by controlling the motor based on the detection results of various sensors. One example of such an electric power steering device is disclosed in Japanese Patent Laid-Open No. 1-293273. 2. Description of the Related Art As described in (1), there is conventionally known an electric power steering apparatus that is configured to drive a motor to return wheels to a neutral position, that is, a position where a turning angle is 0 when the vehicle is parked.

According to such an electric power steering apparatus, the wheels are automatically returned to their neutral positions when the vehicle is parked or stopped, so that the driver of the vehicle intentionally operates the steering wheel when the vehicle is parked or stopped. Even if the wheel is not returned to its neutral position, or even if the driver neglects to return the wheel to its neutral position when the vehicle is parked, the vehicle must always start traveling straight ahead. it can.

[0004]

However, in the conventional electric power steering apparatus as described above, when the vehicle is parked or stopped, the wheels are always automatically returned to the neutral position regardless of the environment. To prevent the vehicle from moving when the vehicle is parked on a slope, the wheel will return to its neutral position even if the driver operates the steering wheel to intentionally make a sharp angle on the wheel. However, there is a problem that the movement of the vehicle cannot be prevented.

In view of the above-mentioned problems in the conventional electric power steering apparatus, the present invention allows the wheels to be automatically returned to their neutral positions when the vehicle is parked on a horizontal road surface. Therefore, it is an object of the present invention to provide an improved electric power steering device capable of maintaining a state where a vehicle is parked on a slope with a turning angle intentionally provided.

[0006]

According to the present invention, as described above, the above-described object is to provide a motor M1 for driving a steering linkage member S and a steering state for detecting a steering state of a vehicle. An electric power steering apparatus having a detection means M2 and a control means M3 for controlling the motor according to the detected steering state is provided, and a parking detection means M4 for detecting the parking state of the vehicle and a parking state of the vehicle are detected. When detected, the returning means M5 for controlling the motor to return the steering linkage member to its neutral position, the slope determining means M6 for determining whether the parking road surface is a slope, and the parking road surface for a slope. The electric power steering apparatus may further include a prohibiting means M7 for prohibiting neutral position return control for the motor by the returning means. It is achieved by the device.

[0007]

According to the above construction, when the parking state of the vehicle is detected by the parking detecting means M4, the returning means M is returned.
The steering linkage member S is returned to its neutral position by controlling the motor M1 by 5. However, when the slope determining means M6 determines that the parking road surface is a slope, the prohibiting means M7 causes the returning means M5. Since the neutral position return control for the motor is prohibited, the wheels are automatically returned to their neutral position when the vehicle is parked on a horizontal road surface, and the wheels are returned to their neutral position when the vehicle is parked on a slope. Not be
Therefore, if the wheel is intentionally provided with a turning angle, that state is maintained as it is.

[0008]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 2 is a schematic configuration diagram showing one embodiment of the electric power steering apparatus according to the present invention, and FIG.
3 is a block diagram showing an electronic control device shown in FIG.

In FIG. 2, reference numeral 10 denotes a steering wheel. The steering wheel 10 is a rack bar 1 as a steering linkage member via a steering shaft 12 and a steering gear box 14.
6 is driven. A power unit 20 is drivingly connected to the steering shaft 12 by a gear reduction mechanism 18. The power unit 20 is a motor 22
And an electromagnetic clutch 24 for selectively drivingly connecting the gear reduction mechanism 18 and the motor 22.

In the illustrated embodiment, the steering shaft 12 is provided with a steering angle sensor 26 for detecting a steering angle θ and torque sensors 28 and 30 for detecting steering torques T ₁ and T ₂ , respectively. The outputs of these sensors are supplied to the electronic control unit 32.
Further, the electronic control unit 32 is provided with a signal indicating the vehicle speed V detected by the vehicle speed sensor 34, a signal indicating the rotation angle φ of the motor 22 detected by the rotation angle sensor 36, and whether the ignition switch (SW) 38 is turned off. A signal indicating whether or not, a signal indicating the inclination angle α of the vehicle in the front-rear direction detected by the inclination sensor 40, and a mode selection switch for selecting an auto mode in which the wheels are automatically returned to the neutral position when the vehicle is parked. A signal indicating whether or not the mode selected by the (SW) 42 is the auto mode is also input.

Power is supplied to the electronic control unit 32 from the power source 4.
4 through the power supply holding circuit 46. The power supply holding circuit 46 is turned on when the ignition switch 38 is turned on, and the electronic control unit 3
Unless the supply of the control current from 2 is stopped, even if the ignition switch is turned off, the on state is maintained and the electric power is continuously supplied to the electronic control unit. The power supply holding circuit may have any structure known in the art, and for example, Japanese Patent Application No. 4-483 (file number AT-4853) filed by the same applicant as the present applicant. ), As shown in FIG.

As shown in detail in FIG. 3, the electronic controller 32 includes a microcomputer 48, which is a central processing unit (CPU) 50.
, Read only memory (ROM) 52, random access memory (RAM) 54, and input port device 56
And an output port device 58, which are connected to each other by a bidirectional common bus 60.

As will be described later, the electronic control unit 32 outputs a control signal to the electromagnetic clutch 24 via the drive circuit 64 at the start of operation to drive and connect the gear reduction mechanism 18 and the motor 22 and is detected by each sensor. Steering torque T1,
The steering assist amount is calculated based on T2 and the like, and a voltage signal corresponding to the assist amount is output to the motor 22 via the drive circuit 62. Further, as will be described in detail later, the electronic control unit 32 controls the motor to return to the neutral position when the vehicle is parked, and thereafter stops the output of the control signal to the clutch 24 to release the clutch.

The operation of the illustrated embodiment will now be described with reference to the flow chart shown in FIG.

First, in step 10, the control signal is output to the clutch 24 to connect the clutch,
In step 20, a signal indicating the detection value detected by the steering angle sensor 26 or the like is read, and step 30
In this case, the steering assist amount is calculated based on the steering torques T1 and T2 detected by the torque sensors 28 and 30, the vehicle speed V detected by the vehicle speed sensor 34, and the like.

Since the calculation of the assist amount in step 30 is well known in the art and does not form the subject of the present invention, a detailed description will be given of the procedure of calculating the assist amount. Although omitted, the assist amount may be calculated in any manner as long as it is calculated according to at least the steering torque.

In step 40, a control signal of a voltage corresponding to the assist amount calculated in step 30 is output to the motor 22 via the drive circuit 52, whereby a required assist force is generated. Go to step 50.

In step 50, it is judged whether or not the ignition switch 38 is turned off.
When it is determined that the ignition has been switched off, the vehicle speed V is set to the reference value Vo (0
Is a positive constant close to
If it is determined that ≦ Vo, step 70
The absolute value of the average value T of the steering torques T1 and T2 detected by the torque sensors 28 and 30 is the reference value To.
It is determined whether or not (a positive constant close to 0) or less, and when it is determined that | T | ≦ To, the process proceeds to step 80. Incidentally, when the determination is NO in any of steps 50 to 70, the process returns to step 20.

In step 80, it is judged whether or not the inclination angle α of the vehicle detected by the inclination angle sensor 40 is equal to or larger than the reference value α o (a positive constant), that is, whether or not the road surface is a slope. If it is determined that α ≧ αo, the process proceeds to step 160. If it is determined that α ≧ αo is not satisfied, the mode selected by the mode selection switch 42 in step 90 is set to auto. Whether or not the mode is set is determined. If it is determined that the selected mode is not the auto mode, step 16
When it is determined that the mode is the auto mode, the timer is started in step 100.

In step 110, the steering angle sensor 26
The steering angle θ detected by is read, and in step 120 it is determined whether or not the absolute value of the steering angle θ is less than or equal to a reference value θo (a positive constant close to 0). θ |
If it is determined that ≦ θo, step 16
When it is determined that | θ | ≦ θo is not satisfied, the control amount for the motor 22 necessary for reducing the steering angle θ by a predetermined value is calculated in step 130, and in step 140. The control signal corresponding to the control amount calculated in step 130 is output to the motor 22 via the drive circuit 62, whereby the steering shaft 18 in the direction not shown in the drawing approaches the steering angle of the wheel approaching zero.
And the rack bar 16 is driven.

In step 150, it is determined whether the count value Tt of the timer is greater than or equal to the reference value Tc (a positive constant). If it is determined that Tt ≥ Tc is not satisfied, step 110 is performed. Returning to step 160, if it is determined that Tt ≧ Tc, the process proceeds to step 160. In this case, the reference value Tc is set to the time required for the wheel to return to its neutral position from the time when the neutral position return control is started with the wheel turning angle at the maximum value.

At step 160, energization of the motor 22 is stopped and the output of the control signal to the electromagnetic clutch 24 is stopped, so that the clutch is released. When the output of the control signal is stopped, the power supply to the electronic control unit 32 is stopped.

Thus, according to the illustrated embodiment, when the vehicle is parked on the horizontal road surface with the mode selection switch 42 set to the automatic mode, the determination in step 50 to 70 is YES. In step 80, a determination of NO is performed, in step 90, a determination of yes is performed, and in step 120, steps 110 to 140 are repeatedly executed until the wheels are automatically rotated. Then returned to its neutral position.

Even if the vehicle is parked on a horizontal road surface, if the mode selection switch 42 is set to the manual mode, a negative determination is made in step 90, resulting in steps 110-110. The neutral position return control of 140 is not executed, and the wheels are maintained in the state of the corner when parking.

Therefore, for example, when the vehicle is parked in a narrow parking space, it is unavoidable that the vehicle is parked in a state where the wheels have a certain turning angle, and when the vehicle starts traveling, the wheels are started at the turning angle. In a situation where it is necessary to set the mode selection switch 42 to the manual mode, it is possible to maintain a state in which the wheels have a required turning angle, and thus when the vehicle starts to run. It is possible to reduce the steering burden on the driver.

Further, even if the mode selection switch 42 is set to the automatic mode, if the parking road surface is a slope, the determination in step 80 is YES, and in this case as well, steps 110 to 110 are performed. Since the neutral position return control of 140 is not executed, the wheels are maintained in the turning angle state during parking.

Therefore, when the vehicle is parked on a slope, the driver intentionally gives a corner to the wheel to prevent the vehicle from moving, and when the driver parks the vehicle on the slope, the wheel does not return to the neutral position and the wheel is turned. Since the corner is maintained, it is possible to prevent the wheel from returning to the neutral position and the vehicle from moving down the slope.

In the above embodiment, whether or not the parking road surface is a slope is determined by the inclination angle sensor 40 which detects the inclination angle of the vehicle in the longitudinal direction. Whether or not the road surface is a slope may be determined by any means, for example, it may be determined by the inclination of the seat belt anchor, or the height of the liquid surface of the cooling water of the radiator or the wiper washer can be determined. Alternatively, the detection may be performed at two locations separated from each other in the front-rear direction and the detection height deviation may be determined.

Although the present invention has been described in detail above with reference to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art that it is possible.

[0031]

As is apparent from the above description, according to the present invention, when the parking state of the vehicle is detected by the parking detecting means M4, the motor M1 is controlled by the returning means M5 so that the steering linkage member can be controlled. S
Is returned to its neutral position, the slope determination means M
When it is determined by 6 that the parking road surface is a slope, the prohibiting means M7 prohibits the neutral position return control for the motor by the returning means M5. Therefore, when the vehicle is parked on the horizontal road surface, the wheels are automatically turned. It can be returned to the neutral position for convenience when the vehicle starts to run, and when the vehicle is parked on a slope, the wheels cannot be returned to the neutral position, and therefore the wheels are intentionally provided with a turning angle. In this case, that state can be maintained as it is, and thus it is possible to reliably prevent the prevention of movement of the vehicle during hill parking from being impeded.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of an electric power steering device according to the present invention in correspondence with the description of the claims.

FIG. 2 is a schematic configuration diagram showing one embodiment of an electric power steering device according to the present invention.

FIG. 3 is a block diagram showing the electronic control device shown in FIG. 2.

4 is a flowchart showing a control flow achieved by the electronic control device shown in FIGS. 2 and 3. FIG.

[Explanation of symbols]

 10 ... Steering wheel 12 ... Steering shaft 14 ... Steering gear box 16 ... Rack bar 22 ... Motor 24 ... Electromagnetic clutch 26 ... Steering angle sensor 28, 30 ... Torque sensor 32 ... Electronic control unit 34 ... Vehicle speed sensor 36 ... Rotation angle sensor 38 ... Ignition switch 40 ... Tilt angle sensor 42 ... Mode selection switch

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B62D 133: 00 137: 00

Claims (1)

[Claims] 1. An electric power steering apparatus having a motor for driving a steering linkage member, a steering state detecting means for detecting a steering state of a vehicle, and a control means for controlling the motor according to the detected steering state. Then, parking detection means for detecting the parking state of the vehicle, return means for controlling the motor to return the steering linkage member to its neutral position when the parking state of the vehicle is detected, and the parking road surface on a slope. An electric power steering apparatus comprising: a slope determining means for determining whether or not there is a vehicle; and a prohibiting means for prohibiting the neutral position return control for the motor by the returning means when the parking road surface is a slope.