JPH0667737B2 - 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 maneuverability by increasing the above ratio from the standpoints 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 demands, 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. As shown in FIG. 11, a continuously variable transmission mechanism c formed by winding a V-belt c ₃ between a steering handle a and a steering column b is provided, and a signal from a vehicle speed sensor d is applied to the 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 tearing column b at the time of high speed, that is, the ratio of the wheel steering angle to the constant steering wheel steering angle becomes small, while the transmission ratio becomes large at low speed. 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 in which the transmission ratio varying means D that changes according to the signal of the vehicle speed sensor C is provided, the failure detecting means E for detecting the failure of the vehicle speed sensor C, and the detecting means E are the vehicle speed sensor C.
Control means F for causing the transmission ratio varying means D to perform a predetermined operation when the failure is detected. This control means F
Specifically, when the vehicle speed sensor C malfunctions, a signal is output to the transmission ratio varying means D so as to fix the transmission ratio to a predetermined set value. Depending on whether the failure of the vehicle speed sensor C occurs in the high speed range or the low speed range, the time from when the failure is detected to when the failure is fixed to the set value is performed. In this case, as a mode of making this time different, there is a case where the transition operation to the set value of the transmission ratio is delayed from the time of the failure detection, and a case where this transition operation is gradually performed.

(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 the middle of the variable range of the transmission ratio varied by the transmission ratio varying means D, the traveling stability is deteriorated during high-speed traveling when the vehicle speed sensor is out of order, and during low-speed traveling. Deterioration of maneuverability and the like can be avoided, and the so-called fail-safe function can ensure at least the same steering performance as that of the conventional steering device with a constant transmission ratio.

In particular, according to the present invention, when the vehicle speed sensor has a failure, the transfer ratio shifts to the set value in the high speed range and in the low speed range. The fail-safe function as described above is performed in conformity with the traveling state at the time of failure because it is performed at different times until it is fixed. In that case, for example, in the high speed range, the control is performed such that the shift to the set value is delayed or gradually performed from the time of occurrence of a failure, and the sensor value is quickly shifted to the set value in the low speed range. In this case, when the sensor fails in the high speed range, the transmission ratio suddenly changes in the direction in which the transmission ratio increases, and the problem that the wheels steer more than expected is prevented.

(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. A steering gear device 5, and a pitman arm 7 and a tie rod 8 that steer left and right steering wheels 6, 6 by the output of the gear device 5.
And the like, and between the steering wheel shaft 3 and the intermediate shaft 4, the wheel 6, with respect to the rotation angle (steering wheel steering angle: θh) of the steering wheel 2,
Ratio of 6 steering angles (wheel steering angle: θw) (transmission ratio: R = θw /
A transmission ratio variable device 10 for changing 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. Signal S ₂ from the steering wheel angle sensor 13 that detects the steering angle θh of the steering wheel ₂
And are entered.

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. Further, a planetary gear mechanism 17 is provided between the input shaft 14 and the intermediate shaft 4. The planetary gear mechanism 17 includes a sun gear 18 fixed on the input shaft 14.
And a plurality of pinion gears 19 arranged on the sun gear 18.
... 19, a ring gear 20 arranged outside the pinion gears 19 ... 19 and fixed to the intermediate shaft 4, and an input shaft
And a carrier 22 which is rotatably fitted and supported on the pin 14 and supports each of the pinion gears 19 ... 19 via pinion shafts 21 ... 21.
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. Then, when the steering handle 2 or the handle shaft 3 is rotated, the stepping motor 24 is rotationally driven according to the drive signal S ₃ from the controller 11, so that the sun gear 18 in the planetary gear mechanism 17 has a steering angle θh. At the same time as the carrier 22 is rotated by a corresponding amount, the carrier 22 is rotated according to the rotation of the stepping motor 24, whereby the amount of rotation of the ring gear 20 or the intermediate shaft 4 corresponding to the wheel steering angle θw is increased or decreased,
Transmission ratio R of the wheel steering angle θw to the steering wheel steering angle θh
Is variably controlled.

On the other hand, the controller 11 that variably controls the transmission ratio as described above receives the signal S ₁ from the vehicle speed sensor 12 and the signal S ₂ from the steering wheel steering angle sensor 13 as shown in FIG. And a drive signal generator 27 for generating a drive signal according to the calculated value obtained by the calculator 26, and the signal S ₃ output from the signal generator 27 is driven. While being sent to the stepping motor 24 as a signal,
The amount of rotation of the motor 24 is detected by the motor rotation angle sensor 28, and the drive signal generator outputs the feedback signal S _4.
Feedback is given to 27.

Here, the control amount calculation unit 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 constant steering wheel steering angle θ
The wheel steering angle θw with respect to h is reduced to obtain good traveling stability, and the wheel steering angle θw with respect to the constant steering wheel steering angle θh is increased during low speed traveling, which facilitates garage entry and other maneuverability. Will be done.

However, in addition to the above configuration, this controller 11
A vehicle speed sensor failure detection unit 29 for detecting a failure of the vehicle speed sensor 12 based on the signal S ₁ from the vehicle speed sensor 12 is provided. When the failure detector 29 detects a failure of the vehicle speed sensor 12, the control amount calculator 26 shifts the transmission ratio R to a preset value R ₀ in the middle of the variable range shown in FIG. It is designed to operate. Next, the failure detecting operation of the vehicle speed sensor failure detecting section 29 and the operation when the failure occurs in the control amount calculating section 26 will be described with reference to the flowcharts of FIGS.

First, a vehicle speed sensor failure detecting unit 29, in step P ₁ in the flow chart of Figure 8, the read repeatedly vehicle speed V at a constant sampling period on the basis of the signals S ₁ from the vehicle speed sensor 12, currently read in Step P ₂ A difference v between the vehicle speed V and the previously read vehicle speed V'is calculated. 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 execute the current vehicle speed V.
Is replaced with the previous vehicle speed V ', and the above operation is repeated. 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 a steepness that cannot occur at the actual vehicle speed, the steps P ₃ to S ₅ are performed. It is executed to determine that the vehicle speed sensor 12 has failed, and the determination result and the value of the vehicle speed V immediately before the failure determination are sent to the control amount calculator 26.

On the other hand, when the sensor failure detection unit 29 determines that the vehicle speed sensor 12 has failed, the control amount calculation unit 26 executes steps Q ₁ to Q ₂ in the flowchart of FIG. 9 to determine the vehicle speed V immediately before the failure determination. Is input, and it is determined whether the value is larger or smaller than the set value V ₀ . Then, when it is smaller than the set value V ₀ , that is, when the vehicle speed sensor 12 fails in the low speed range of the vehicle, the transmission ratio R is immediately shifted to the set value R ₀ shown in FIG. 7 in step Q ₃ . The drive signal S ₃ is output to the stepping motor 24 via the drive signal generator 27. Therefore, as shown by the arrow (a) in FIG. 7, the set value R _{0 is changed} from the state where the transmission ratio R is large (the state where the reduction ratio 1 / R is small).
And the set value R ₀ is fixed. As a result, when the vehicle speed sensor 12 fails, it is possible to avoid problems such as a reduction in the transmission ratio R in the low speed region and deterioration of maneuverability. In this case, however, the transmission occurs when the sensor 12 fails. Since the ratio R is immediately changed to the set value R ₀ , the above-mentioned problems can be reliably prevented.

However, the vehicle speed V immediately before the failure of the vehicle speed sensor 12 is determined.
Is greater than the set value V ₀ , that is, when the vehicle speed sensor 12 fails in the high speed range, the control amount calculation unit 26 executes steps Q ₂ to Q ₄ and waits for the set time T ₀ to elapse, The time
After T ₀ has elapsed, control is performed to shift the transmission ratio R to the set value R ₀ . That is, in this case, as shown by the arrow (b) in FIG. 7, the state where the transmission ratio R is small (the state where the reduction ratio 1 / R is large) is shifted to the set value R ₀ and fixed,
In the high speed range, it is possible to avoid the transmission ratio R from unnecessarily increasing and the traveling stability being significantly deteriorated. In this case, in particular, the transfer ratio R shifts from when the vehicle speed sensor 12 fails. This will be performed when the set time T ₀ has elapsed, and during this time, for example, it is possible to warn the driver in advance that the transmission ratio R will increase. As a result, during high speed traveling, the transmission ratio R increases without the driver's knowledge due to the failure of the vehicle speed sensor 12, so that the wheels steer more than expected during steering, or the vehicle speed sensor during steering. It is possible to avoid such a problem that 12 is out of order and the transmission ratio R or the steered amount of the wheels is suddenly increased. In this way, stable steering performance is secured when the vehicle speed sensor 12 is out of order during high speed traveling. Will be.

When the vehicle speed sensor fails in the high speed range, instead of the control of shifting the transmission ratio R to the set value R ₀ after the set time T ₀ has passed, the transmission ratio R is gradually set from the time of occurrence of the failure. Value R ₀
You may make it shift to. In this case, as shown in FIG. 10, the control amount calculation unit 26 determines that the vehicle speed sensor 12 has a failure in steps Q ₁ ′ and Q ₂ ′ and that the vehicle speed V immediately before the failure is equal to or higher than the set vehicle speed V _0. When it is determined that there is a certain value, the steps Q ₃ ′ and Q ₄ ′ are repeated to gradually shift the transmission ratio R by a small amount r until reaching the set value R _0, and
It operates to fix the transfer ratio when R ₀ is reached.

(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 in the same manner as a conventional steering device with a constant transmission ratio when the vehicle speed sensor fails, and the transmission ratio becomes unbalanced 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. According to the present invention, in particular, the transition of the transmission ratio to the set value is delayed, for example, immediately when a sensor failure occurs in the low speed range and gradually or slowly when the sensor failure occurs in the high speed range. Since the time from when a sensor failure is detected to when the transmission ratio is fixed at the set value is made different by the and, it is possible to effectively prevent the problem that the transmission ratio does not correspond to the vehicle speed. As described above, if the transfer ratio to the set value is gradually or delayed when the sensor fails in the high speed range, and the time until the transfer ratio is fixed at the set value is lengthened, In this case, it is possible to prevent a problem that the turning amount of the wheel becomes larger than expected or suddenly when the sensor fails, and 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 10 show an embodiment of the present invention. FIG. 2 is a schematic perspective view showing the overall configuration of a steering device, FIG. 3 is an enlarged vertical side view of a transmission ratio varying device, and FIGS. Is Fig. 3 IV-I
FIG. 6 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 failures of the controller. FIG. 10 is a flowchart showing the determination operation and the operation when a failure occurs, and FIG. 10 is a flowchart showing another operation example when a failure occurs. FIG. 11 is a schematic diagram showing the structure of a conventional vehicle speed-sensitive steering device. 1 ... Steering device, 2 ... Steering handle, 6 ... Wheels, 10 ... Transmission ratio varying means, 11 ... Controller, 12 ... Vehicle speed sensor, 26 ... Control means (control amount calculation unit), 29 ... ... Failure detection means (vehicle speed sensor failure detection unit).

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. An intervening vehicle steering device, wherein failure detection means for detecting a failure of the vehicle speed sensor, and the transmission ratio to a predetermined set value when the failure detection means detects a failure of the vehicle speed sensor. In addition to fixing, the transition to the set value is performed with different time from when the failure is detected to when the vehicle speed sensor fails in the high speed range and when the vehicle speed sensor fails in the low speed range until the set value is fixed. A steering device for an automobile, comprising: