JPH0633043B2 - Car steering device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering system, and more particularly to a vehicle speed sensitive steering system in which a transmission ratio of a wheel steering angle to a steering wheel steering angle is changed according to a vehicle speed. .

(Prior Art) Generally, in a steering device of an automobile, a tie rod is laterally displaced through a steering gear device such as a rack and pinion by a rotating operation of a steering handle, and the tie rod is coupled to both ends thereof by displacement. Although the configuration is such that the orientation of the left and right steering wheels is changed, the ratio of the wheel scraping angle (wheel steering angle) to the steering wheel rotation angle (steering wheel steering angle) is set to be constant. Is customary. However, for example, when the vehicle is traveling at high speed, the ratio of the wheel steering angle to the constant steering wheel steering angle is reduced to improve traveling stability,
In addition, it is desirable to improve the operability by increasing the above ratio from the viewpoints of speeding up the behavior of the vehicle at low speed to obtain a good driving feeling and facilitating garage entry.

In order to meet such a demand, for example, according to Japanese Patent Laid-Open No. 58-224852, the ratio of the wheel steering angle to the steering wheel steering angle (transmission ratio = wheel steering angle / steering wheel steering angle) is determined according to the vehicle speed. There has been proposed a vehicle speed-sensitive steering device that is changed. This is because, as shown in FIG. 10, a pair of variable pitch pulleys c ₁ and c _{2 is} provided between the steering wheel a and the steering column b.
While interposed a continuously variable transmission mechanism c formed by wound a V-belt c ₃ between the signal from the vehicle speed sensor d F-V converter e
The stepping motor f input through the motor is provided, and the speed reduction ratio of the speed change mechanism c is controlled to increase as the vehicle speed increases due to the operation of the motor f. According to this, the rotation transmission ratio (1 / reduction ratio) from the steering wheel a to the steering column b at high speed, that is, the ratio of the wheel steering angle to the constant steering wheel steering angle becomes small, and conversely, at low speed, the transmission ratio becomes large. As a result, good steering characteristics corresponding to the vehicle speed can be obtained.

(Problems to be Solved by the Invention) In order for the vehicle speed sensitive steering device as described above to function properly, it is most important that the vehicle speed sensor that detects the vehicle speed is operating normally. is there. In other words, if the vehicle speed sensor fails to detect the vehicle speed correctly, for example, the ratio of the wheel steering angle to the constant steering wheel steering angle becomes large during high-speed traveling, and the traveling stability of the vehicle is impaired. In addition, when the vehicle is traveling at a low speed, the above ratio becomes small, which makes it difficult to put the vehicle in the garage due to the deterioration of maneuverability.

(Means for Solving Problems) An object of the present invention is to prevent the deterioration of the steering performance when the vehicle speed sensor is out of order by addressing the above-mentioned problems relating to the vehicle speed sensitive steering device. In order to achieve that purpose, it is characterized as follows.

That is, the steering device for an automobile according to the present invention is the first
As shown in the figure, the ratio (transmission ratio) of the steering angle of the wheel B to the steering angle of the steering wheel A is transferred from the vehicle speed sensor C during the steering force transmission path for steering the wheels B in response to the steering of the steering wheel A. In the configuration provided with the transmission ratio varying means D that changes according to the signal of the above, the failure detecting means E for detecting a failure of the vehicle speed sensor C, and the low speed traveling operation detecting means F for detecting the equipment operation by the occupant during low speed traveling. And a control means G for causing the transmission ratio varying means D to perform a predetermined operation according to the detection result of the low speed traveling operation detecting means F when the failure detecting means E detects a failure of the vehicle speed sensor C. The low speed traveling operation detecting means F detects a vehicle speed sensor C by detecting a device operation peculiar to the occupant during low speed traveling, for example, an operation of rotating the steering wheel A by a large amount or an operation of shifting the transmission to a low shift stage. It is to detect that the vehicle is in a low speed traveling state regardless of the above. Then, the control means F outputs a signal to the transmission ratio varying means D so as to fix the transmission ratio to a predetermined set value when the vehicle speed sensor C fails, and the shift to the set value is made. The low-speed traveling operation detecting means F is operated at a time point when the occupant detects a device operation during low-speed traveling.

(Operation) According to the above configuration, when the vehicle speed sensor C fails, the transmission ratio by the transmission ratio varying means D is fixed to the set value by the signal from the control means F, whereby the steering device concerned. As in the conventional steering device, the ratio of the wheel steering angle to the steering wheel steering angle is always constant. In that case, if the set value is set to an intermediate value in the variable range of the transmission ratio changed by the transmission ratio changing means D, the traveling stability is deteriorated during high speed traveling or the low speed traveling is caused when the vehicle speed sensor fails. Deterioration of maneuverability at the time is avoided, and at least steering performance similar to that of a conventional steering device with a constant transmission ratio is secured.

In particular, according to the present invention, the transfer of the transmission ratio to the above-mentioned set value when the vehicle speed sensor has a failure is performed at the time when the low-speed traveling operation detecting means F detects the device operation by the occupant during low-speed traveling. Even when a failure of the vehicle speed sensor C occurs in the high speed range, the transmission ratio is shifted to the set value after the vehicle speed decreases to the low speed range. Therefore, when the vehicle speed sensor fails in the high speed range, it is possible to prevent such a problem that the transmission ratio suddenly changes to increase and the wheels steer more than expected.

(Example) Hereinafter, the Example of this invention is described.

First, the overall configuration of the steering apparatus according to the present embodiment will be described with reference to FIG. 2. In the steering apparatus 1, the steering handle 2 and the rotation of the handle 2 are input via the handle shaft 3 and the intermediate shaft 4. The steering gear device 5 and the pitman arm 7 for steering the left and right steering wheels 6, 6 by the output of the gear device 5 and the link mechanism 9 such as the tie rod 8 and the handle shaft 3 are provided. Between the intermediate shaft 4 and the rotation angle of the steering handle 2 (steering wheel steering angle: θh), the ratio of the steering angle of the wheels 6 and 6 (wheel steering angle: θw) (transmission ratio: R =
A transmission ratio variable device 10 that changes θw / θh) is provided. A controller 11 for controlling the transmission ratio variable device 10 is provided, and the controller 11 has a signal S ₁ indicating a vehicle speed V from a vehicle speed sensor 12 for detecting a vehicle speed of the vehicle and the steering wheel. The signal S ₂ from the steering wheel steering angle sensor 13 that detects the steering angle θh of ₂ is input.

Next, the configuration of the transmission ratio variable device 10 will be described with reference to FIGS. 3 to 5. The device 10 has an input shaft 14 arranged on the same axis as the intermediate shaft 4 so as to face the input shaft 14. The rotation of the handle shaft 3 is input through a pair of input gears 15 and 16. Also, this input shaft 1
A planetary gear mechanism 17 is interposed between the intermediate shaft 4 and the intermediate shaft 4. The planetary gear mechanism 17 includes a sun gear 18 fixed on the input shaft 14, a plurality of pinion gears 19 ... 19 arranged on the sun gear 18, and a plurality of pinion gears 19 ... 19 arranged outside the pinion gears 19 ... 4 and a carrier 22 that is fitted to and supported on the input shaft 14 so as to be rotatable relative to each other, and that supports the pinion gears 19 ... 19 via the pinion shafts 21 ... 21. , The carrier 22 is integrally provided with a sector gear 23, and the sector gear 23
A pinion gear 25 fixed to the rotation shaft of the stepping motor 24 is meshed with the. When the steering handle 2 or the handle shaft 3 is rotated, the stepping motor 24 causes the drive signal S from the controller 11 to be transmitted.
_By being rotationally driven according to ₃ , the planetary gear mechanism 1
In FIG. 7, the sun gear 18 is rotated by an amount corresponding to the steering wheel steering angle θh, and at the same time, the carrier 22 is rotated according to the rotation of the stepping motor 24, whereby the ring gear 20 or the intermediate shaft 4 corresponding to the wheel steering angle θw. Is increased or decreased to variably control the transmission ratio R of the wheel steering angle θw to the steering wheel steering angle θh.

On the other hand, the controller 11 which variably controls the transmission ratio as described above, as shown in FIG.
The signals S ₁ from 2, the control amount calculation unit 26 the signal S ₂ and are input from the steering angle sensor 13, the operation section 2
Drive signal generator 27 for generating a drive signal according to the calculated value obtained in step 6, and the signal S ₃ output from the signal generator 27 is sent to the stepping motor 24 as a drive signal. The rotation amount of the motor 24 is detected by the motor rotation angle sensor 28, and is fed back to the drive signal generator 27 as a feedback signal S ₄ .

Here, the control amount calculator 26 sets the transmission ratio R of the wheel steering angle θw to the steering wheel steering angle θh according to the vehicle speed V indicated by the signal S ₁ from the vehicle speed sensor 12 based on a predetermined characteristic. At the same time, the wheel steering angle θw is calculated from the transmission ratio R and the steering wheel steering angle θh, and the drive signal S ₃ is output to the stepping motor 24 via the drive signal generating unit 27 so as to be the wheel steering angle θw. . In this case, the characteristic of the transmission ratio R with respect to the vehicle speed V is such that the transmission ratio R decreases as the vehicle speed V increases (the reduction ratio 1 / R of the planetary gear mechanism 17 increases as shown in FIG. Is set). As a result, the wheel steering angle θw with respect to the constant steering wheel steering angle θh is reduced during high-speed traveling, and good traveling stability is obtained, while the wheel steering angle θw with respect to the constant steering wheel steering angle θh is increased during low-speed traveling, which results in garage entry. The maneuverability will be improved.

However, in addition to the above-mentioned configuration, the controller 11 has the sensor 1 based on the signal S ₁ from the vehicle speed sensor 12.
The vehicle speed sensor failure detection unit 29 for detecting the failure of No. 2 is provided. Then, this failure detection unit 29 is the vehicle speed sensor 1
2 is detected, the control amount calculation unit 26 refers to the steering wheel steering angle θh indicated by the signal S ₂ from the steering wheel steering angle sensor 13 and refers to the transmission ratio R in the middle of the variable range shown in FIG. The operation of shifting to a preset set value R ₀ is performed. Next, the failure detection operation of the vehicle speed sensor failure detection section 29 and the operation when the control amount calculation section 26 fails will be described with reference to the flowcharts of FIGS.

First, the vehicle speed sensor failure detection unit 29 determines the signal S from the vehicle speed sensor 12 in step P ₁ of the flowchart of FIG.
_{Based on 1} , the vehicle speed V is repeatedly read at a constant sampling cycle, and in step P ₂ , the difference v between the vehicle speed V read this time and the vehicle speed V ′ read last time is calculated. And
When the difference v is smaller than the set value v _0, it is determined that the vehicle speed sensor 12 is normal, and steps P ₃ to P ₄ are executed to replace the current vehicle speed V with the previous vehicle speed V ′, and then Repeat the operation of. However, when the difference v is larger than the set value v ₀ , in other words, when the vehicle speed V as the sensor output value changes at such a steepness that the actual vehicle speed cannot occur, the steps P ₃ to S ₅ are performed. It is determined that the vehicle speed sensor 12 has failed, and the determination result is sent to the control amount calculator 26.

On the other hand, when the sensor failure detection unit 29 determines the failure of the vehicle speed sensor 12, the control amount calculation unit 26 executes steps Q ₁ to Q ₂ of the flowchart of FIG. The steering wheel angle θh at that time indicated by the signal S ₂ is read, and the value is set to the set value θh.
_It is determined whether it is larger or smaller than ₀ . When the steering wheel angle θh is smaller than the set value θ ₀ , that is, when the vehicle is not traveling at a low speed, a distinctive large steering wheel operation is not performed, and therefore it is not possible to determine that the vehicle speed is in the low speed range, step Q ₂ and Q ₃ are repeatedly executed. In this case, control for changing the transfer ratio R is not performed, and the transfer ratio R
Is fixed to the transmission ratio when the vehicle speed sensor 12 fails.
Therefore, when the vehicle speed sensor 12 fails in the high speed range, the transmission ratio R is kept small, and a situation in which the wheel steering angle θw with respect to the constant steering wheel steering angle θh becomes large and traveling stability is deteriorated during high speed traveling is prevented. It Then, when the steering angle θh larger than the set value θ ₀ is detected, in other words, when it is confirmed that the vehicle speed is in the low speed range, the control amount calculation unit 26 executes steps Q ₃ to Q _4. , The transmission ratio R as shown by the arrow (a) in FIG.
The drive signal S ₃ is output to the stepping motor 24 via the drive signal generator 27 so as to shift to the set value R ₀ . As a result, the transmission ratio R is fixed to the set value R ₀ after the occurrence of a failure of the vehicle speed sensor 12, and the transmission ratio R is maintained in the low speed range.
Of the steering device with a constant transmission ratio is avoided by avoiding the problems that the steering ratio is undesirably reduced and the maneuverability is deteriorated, and that the transmission ratio R is unduly increased in a high speed range and traveling stability is deteriorated. Similar steering performance will be secured.

Then, particularly when the vehicle speed sensor 12 is out of order, the transmission ratio R
Since the transition to the set value R ₀ of the above is performed only in the low speed range, such a transition is performed in the high speed range. For example, during high speed traveling, while the driver is not aware of it due to a failure of the vehicle speed sensor 12. It is possible to avoid a problem that the transmission ratio R becomes large and the wheels steer more than expected during steering, or the vehicle speed sensor 12 malfunctions during steering and the transmission ratio R or the steering amount of the wheels suddenly increases. Will be. In this way, even if the vehicle speed sensor 12 fails during high-speed traveling, stable steering performance can be ensured.

As a means for detecting that the vehicle speed is in the low speed range without relying on the sensor 12 when the vehicle speed sensor 12 fails, a method of detecting that the steering wheel steering angle θh is larger than the set value θ ₀ as described above is used. Besides, for example, there is a method of detecting that the transmission included in the automobile has been shifted to a low shift stage, and in short, it is sufficient to detect a device operation specific to the occupant during low speed traveling.

(Effect of the Invention) As described above, according to the present invention, in a vehicle speed sensitive steering device in which a transmission ratio of a wheel steering angle to a steering wheel steering angle is changed according to a vehicle speed, a vehicle speed sensor for detecting a vehicle speed is provided. Since the transmission ratio is fixed to the set value in the event of a failure, the steering device functions like a conventional steering device with a constant transmission ratio when the vehicle speed sensor fails, and the transmission ratio remains constant during high-speed traveling. It is possible to avoid deterioration of driving stability due to further increase in speed and deterioration of maneuverability due to unnecessary reduction of transmission ratio at low speed running, and at least to secure steering performance similar to that of conventional steering devices with constant transmission ratio. Will be done. Further, according to the present invention, in particular, the transfer ratio is set to the set value after confirming that the vehicle speed is in the low speed range. By shifting to the set value, it is possible to prevent the problem that the turning amount of the wheel becomes larger than expected or suddenly, and the stable steering performance is secured even when the vehicle speed sensor fails.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of the present invention. 2 to 9 show an embodiment of the present invention. FIG. 2 is a schematic perspective view showing the overall configuration of the steering device, FIG. 3 is an enlarged vertical side view of the transmission ratio varying device, and FIGS. Is Figure 3 IV
6 is a front view of the same section taken along line IV and line VV, FIG.
FIG. 7 is a block diagram showing the configuration of the controller, FIG. 7 is a characteristic diagram of control by the controller, and FIGS. 8 and 9 are flow charts showing a failure determination operation of the controller and an operation when a failure occurs. FIG. 10 is a schematic diagram showing the structure of a conventional vehicle speed-sensitive steering device. 1 ... Steering device, 2 ... Steering handle, 6 ... Wheel, 10 ... Transmission ratio varying means, 11 ... Controller, 12 ... Vehicle speed sensor, 13 ... Low speed traveling operation detecting means (steering wheel steering angle sensor) , 26 ... Control means (control amount calculation section), 29 ... Failure detection means (vehicle speed sensor failure detection section).

Claims (1)

[Claims] 1. A transmission ratio variable means for changing a transmission ratio of a wheel steering angle to a steering wheel steering angle according to an output signal of a vehicle speed sensor in a steering force transmission path for steering a wheel in accordance with steering of a steering wheel. A steering device for an automobile interposed, wherein a failure detection means for detecting a failure of the vehicle speed sensor, a low speed traveling operation detection means for detecting an operation of an occupant during low speed traveling, and the failure detection means are vehicle speed sensors. And a control means for fixing the transmission ratio to a predetermined set value when the low-speed traveling operation detecting means detects an equipment operation during low-speed traveling when the failure is detected. Steering device.