JPS62238166A - Steering device for automobile - Google Patents

Abstract

PURPOSE:To prevent deterioration of steering performance by fixing the transmission ratio of the wheel steering angle to a set value when failure in a speed sensor is detected, and performing the conversion to the set value at different timings in a high speed area and low speed area. CONSTITUTION:Control means F causes transmission ratio changing means D to perform a predetermined operation, when failure detecting means E detects a failure in a speed sensor C. In the concrete, the control means F transmits a signal to the transmission ratio changing means D to fix the transmission ratio to a set value when such a failure occurs. At this time, if failure in the speed sensor C occurs in a high speed area, conversion to the set value is performed at a timing, and if in a low speed area, it is performed at another timing. For example, conversion is gradually performed in the high speed area, while it is rapidly performed in the low speed area. This prevents unexpected increase of the amount of steering change which would be caused by abruptly increasing change of the transmission ratio on occurance of the sensor failure in the high speed area.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a steering device for an automobile, particularly a heavy speed-sensitive steering device in which the transmission ratio of the wheel steering angle to the steering wheel steering angle is varied in accordance with the vehicle speed. Regarding.

(Prior Art) In general, a steering system of an automobile displaces a tie rod in the lateral direction via a steering gear device such as a rack-and-binion by rotating a steering handle. Although the steering wheel is configured to change the direction of the left and right steering wheels, the ratio of the turning angle of the wheels (wheel steering angle) to the rotation angle of the steering handle (steering wheel steering angle) is set constant. It is customary. However, for example, when the vehicle is running at high speed, the ratio of the wheel steering angle to the constant steering wheel steering angle is reduced to improve driving stability.
Furthermore, when driving at low speeds, it is desirable to increase the above-mentioned ratio to improve maneuverability, from the standpoint of making the behavior of the vehicle more agile to obtain a good driving feeling, and making it easier to park the vehicle in a garage.

Therefore, in order to meet such demands, for example, according to Japanese Patent Application 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 changed depending on the vehicle speed. A vehicle speed-sensitive steering device that changes the vehicle speed has been proposed. As shown in FIG. 11, a pair of variable pitch boots 901 and 02 are installed between the steering handle a and the steering column b.
In addition to interposing a continuously variable transmission mechanism C with a V-belt C3 wound therebetween, the signal from the vehicle speed sensor d is converted into F-■
The vehicle is equipped with a stepping motor f to which input is input via a stepping motor f, and as the vehicle speed increases due to the operation of the motor, the reduction ratio of the transmission mechanism C increases. According to this, at high speed, the handle a
The rotation transmission ratio from to steering column b (1/reduction ratio), that is, the ratio of the wheel steering angle to a constant steering wheel steering angle, becomes small, and conversely, at low speeds, the transmission ratio becomes large, resulting in good steering according to the vehicle speed. characteristics will be obtained.

(Problems to be Solved by the Invention) By the way, for the vehicle speed sensitive steering device as described above to function well, it is most important that the vehicle speed sensor that detects the vehicle speed is operating normally. It is. In other words, if the vehicle speed sensor malfunctions and does not detect the vehicle speed correctly, for example, when driving at high speed, the ratio of the wheel steering angle to a constant steering wheel steering angle increases, impairing the driving stability of the vehicle, and vice versa. When driving at low speeds, the above ratio decreases, making it difficult to park the vehicle due to poor maneuverability.
Steering performance deteriorates significantly.

(Means for Solving the Problems) An object of the present invention is to deal with the above-mentioned problems regarding vehicle speed sensitive steering devices and to prevent deterioration of steering performance when a vehicle speed sensor fails. In order to achieve this purpose, it is characterized by the following structure.

That is, the automobile steering device according to the present invention has the first
As shown in the figure, during the steering force transmission path that turns the wheels B in response to the steering of the steering wheel A, the ratio of the steering angle of the wheels B to the steering angle to the steering wheel (transmission ratio) is detected from the vehicle speed sensor C. In the structure provided with a transmission ratio variable means for changing the transmission ratio according to a signal of
and control means F for causing the transmission ratio variable means to perform a predetermined operation when a failure of the transmission ratio variable means is detected. Specifically, this control means F outputs a signal to the transmission ratio variable means to fix the transmission ratio at a predetermined setting of 1 when the vehicle speed sensor C fails. 03 is made so that the transition to the set value is performed at different timings depending on whether the failure of the vehicle speed sensor C occurs in a high speed range or a low speed range.

(Function) According to the above configuration, when the vehicle speed sensor C fails, the transmission ratio by the transmission ratio variable means is fixed at the set value by the signal from the control means E, and thereby In the steering device, the ratio of the wheel steering angle to the steering wheel steering angle is always constant, as in conventional steering devices. In that case, if the above set value is set to a value in the middle of the variable range of the transmission ratio that is changed by the transmission ratio variable means, it is possible to prevent the deterioration of running stability during high speed driving when the vehicle speed sensor fails, Therefore, deterioration of maneuverability during operation is avoided, and at least the same steering performance as a conventional steering device with a constant transmission ratio is ensured.

In particular, according to the present invention, the transmission ratio is shifted to the set value when the vehicle speed sensor fails at different timings depending on when the sensor fails in a high speed range and when the sensor fails in a low speed range, for example. In the high speed range, the transition to the set value is delayed or gradually performed from the time of failure occurrence, and in the case of a sensor failure in the low speed range, the transition to the set value is performed quickly. This will prevent problems such as a sudden change in the transmission ratio in the direction of increasing the transmission ratio in the event of a sensor failure in a high-speed range, causing the wheels to turn more than expected.

(Example) Examples of the present invention will be described below.

First, the overall configuration of the steering device according to the present embodiment will be explained with reference to FIG. It is composed of a steering gear device 5, and a link mechanism 9 consisting of a pitman arm 7, a tie rod 8, etc., which steer left and right steering wheels 6.6 by the output of the gear device 5, and a link mechanism 9 that includes a pitman arm 7, a tie rod 8, etc. A ratio (transmission ratio: R-
A transmission ratio variable device ffff10 for changing the transmission ratio (θW/θh) is provided. A controller 11 is provided to control the variable transmission device 10, and the controller 11 receives a signal S1 indicating the vehicle speed V from a vehicle speed sensor 12 that detects the vehicle speed of the vehicle, and a signal S1 indicating the vehicle speed V from the vehicle speed sensor 12 that detects the vehicle speed of the vehicle. (ffi number S2) from the steering wheel angle sensor 13 which detects the steering angle Oh is inputted.

Next, the configuration of the variable transmission device 1O will be explained with reference to FIGS. The rotation of the handle @3 is inputted via a pair of input gears 15 and 16. Also, this input shaft 1
A planetary tooth IJ mechanism 17 is interposed between the intermediate shaft 4 and the intermediate shaft 4. This planetary gear mechanism 17 includes a ring 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 of these pinion gears 19...19. n ring gears 20 fixed to the intermediate shaft 4, and a pinion shaft 21 which is fitted and supported on the input shaft 14 so as to be relatively rotatable.
... 21, and a carrier 22 that supports one of the pinion gears through the carrier A722, and a sector gear 23 is integrally provided on the carrier A722, and a stepping motor is connected to the sector gear 23. A pinion gear 25 fixed to the rotating shaft 24 is engaged with the rotating shaft.

Then, when the steering wheel 2 or the steering wheel @3 is rotated, the stepping motor 24 is activated by the controller 5.
In the planetary gear mechanism 17, the sun gear 18 is rotated by a distance corresponding to the steering wheel steering angle θh, and at the same time, the carrier 22 is rotated in accordance with the rotation of the stepping motor 24. As a result, the rotation speed of the ring gear 20 or the intermediate shaft 4 corresponding to the wheel steering angle θW is increased or decreased, and the transmission ratio R of the wheel steering angle θ to the above-mentioned steering wheel steering angle θh is variably controlled. ing.

On the other hand, the controller 1--which variably controls the transmission ratio as described above--
○-ra 11 is the vehicle speed sensor 1, as shown in FIG.
2 and a signal S2 from the steering wheel angle sensor 13, and a drive signal generator that generates a drive signal according to the calculated value obtained by the mum control section 26. The signal S3 outputted from the signal generation section 27 is sent to the stepping motor 24 as a drive signal, and the rotation direction of the motor 24 is detected by the motor rotation angle sensor 28 and feedback is provided. The negative signal is fed back to the open drive signal generating section 27 as a signal S4.

Here, the above-mentioned control t11m calculation unit 26 operates on the vehicle speed sensor 12.
The steering wheel steering angle θh is determined according to the vehicle speed V indicated by the signal S1 from
Set the transmission ratio R of the middle wheel steering angle θW to
A drive signal @S3 is output to the stepping motor 24 via the drive signal generator 27 so that the signal @S3 becomes W. In that case,
The characteristics of the transmission ratio 17 with respect to the vehicle speed V are such that as the vehicle speed V increases, the transmission ratio R decreases as shown in FIG. ) is set. As a result, when driving at high speed, the wheel steering angle θW with respect to a constant steering wheel steering angle θh becomes small and good driving stability is obtained, and when driving at low speed, the wheel steering angle θW with respect to a constant steering wheel steering angle θh becomes small.
This increases maneuverability, making it easier to park the vehicle in a garage.

However, in addition to the above-mentioned configuration, this controller 11 also includes a sensor 12 based on a signal @S1 from the vehicle speed sensor 12.
A vehicle speed sensor failure detection section 29 is provided to detect failure of the vehicle speed sensor. This failure detection section 29 is connected to the vehicle speed sensor 12.
When a failure is detected, the control m calculation section 26 sets the transmission ratio [< to a predetermined set value R in the middle of the variable range shown in FIG.

It is designed to perform an operation that causes the transition to . Next, the failure detection operation and control 1ff of this vehicle speed sensor failure detection section 29
The operation of the i calculation unit 2G when a failure occurs will be described with reference to the flowcharts of FIGS. 8 to 10.

First, the vehicle speed sensor failure detection unit 29 detects the signal S from the vehicle speed sensor 12 in step P1 of the flowchart in FIG.
1, the vehicle speed V is repeatedly read at a constant sampling period, and in step P2, the difference y between the vehicle speed V read this time and the vehicle speed V' read last time is calculated. and,
When this difference ■ is smaller than the setting 1iflVo, it is determined that the vehicle speed sensor 12 is normal, and steps P3 and P4 are executed to replace the current vehicle speed ■ with the previous vehicle speed v', and then repeat the above operation. . However, when the above-mentioned difference ■ is larger than the set value v□, in other words, when the vehicle speed V as the sensor output value changes at a rapid rate that cannot occur at the actual vehicle speed, steps P3 to S5 are executed. ,
It is determined that the vehicle speed sensor 12 has failed, and the determination result and the value of the vehicle speed ■ at the time of failure determination are used in the control m calculation unit 2.
Send on 6.

On the other hand, when the sensor failure detection unit 29 determines that the vehicle speed sensor 12 has failed, the control m calculation unit 26 executes steps Q1 to Q2 of the flowchart in FIG. 9, and inputs the vehicle speed ■ immediately before the failure determination. At the same time, it is determined whether the value is larger or smaller than the setting IVo. When the value is smaller than the set value Vo, 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 Ro shown in FIG. 7 in step Q3. A driving signal S3 is outputted to the stepping signal 24 via the signal generating section 27. Therefore, as shown by the arrow (A) in FIG. 7, the transmission ratio R is shifted from a state where it is large (a state where the reduction ratio 1/R is small) to the set value Ro, and is fixed at the set value Ro. . As a result, when the vehicle speed sensor 12 fails, problems such as the transmission ratio becoming unnecessarily small in the low speed range and deteriorating maneuverability can be avoided. Since the transmission ratio 1) is immediately shifted to the set value Ro, the above-mentioned problems are reliably prevented.

However, when the vehicle speed immediately before the failure of the vehicle speed sensor 12 is determined to be higher than the set value Vo, that is, when the failure of the vehicle speed sensor 12 occurs in a high speed range, the control M calculation unit 26 executes steps Q2 to Q4. and waits for the set time TO to elapse, and when the time TO has elapsed (n), control is performed to shift the transmission ratio R to the set value Ro. In other words, in the case of As shown in the figure, when the transmission ratio R is shifted from a small state (a state where the reduction ratio 1/R is large) to the set value Ro and is fixed, the transmission ratio R becomes unnecessarily large in the high-speed range, resulting in poor running stability. Particularly in this case, the transmission ratio R is shifted after a set time To has elapsed from the occurrence of a failure in the vehicle speed sensor 12, and during this time, for example, It is possible to warn the driver in advance that the transmission ratio R will increase.This allows the transmission ratio R to increase without the driver's knowledge during high-speed driving due to a failure in the vehicle speed sensors 1 and 12. Therefore, it is possible to avoid problems such as the wheels turning more than expected during steering, or the vehicle speed sensor 12 malfunctioning during steering and the transmission ratio R or wheel turning m suddenly becoming busy. In this way, J3 while driving at high speed
Stable steering performance is ensured even when the vehicle speed sensor 12 in the vehicle is out of order.

In addition, when the vehicle speed sensor fails in a high-speed range, instead of controlling the transmission ratio R to shift to the set value RO after the elapse of the set time To as described above, the transmission ratio R is gradually changed to the set value Ro from the time of the failure. You may also make the transition to . In this case, the control t
As shown in FIG. 10, when the lOffi calculation unit 26 determines in steps Q+' and Q2' that the vehicle speed sensor 12 is malfunctioning and that the vehicle speed V immediately before the occurrence of the malfunction is in a high-speed range equal to or higher than the set vehicle speed Vo, Repeat steps Q3' and Q4' until the transmission ratio R reaches the set value Ro.
The transmission ratio is gradually shifted one by one, and the transmission ratio is fixed when the set value RO is reached.

(Effects of the Invention) As described above, according to the present invention, in a vehicle speed-sensitive steering device in which the transmission ratio of wheel steering angle to steering wheel steering angle is changed according to vehicle speed, a vehicle speed sensor that detects vehicle speed is used. Since the transmission ratio is fixed at the set value in the event of a failure, the steering device functions in the same way as a conventional steering device with a fixed transmission ratio when the vehicle speed sensor fails. This avoids the deterioration of driving stability due to an unnecessarily large size and the deterioration of maneuverability due to an unnecessarily small transmission ratio when driving at low speeds, and provides at least the same steering performance as a conventional steering device with a constant transmission ratio. It will be secured.

Particularly, according to the present invention, the transmission ratio is shifted to the set value in a low speed range, such as immediately when a sensor fails in a low speed range, and gradually or staggered when a sensor fails in a high speed range. Since the timing is different in the high-speed range, problems caused by the transmission ratio not corresponding to the vehicle speed are effectively prevented, and the amount of wheel turning is more than expected especially in the case of a sensor failure in the high-speed range. This prevents problems such as sudden changes in the speed of the vehicle, and ensures stable steering performance even when the vehicle speed sensor fails.

[Brief explanation of drawings]

FIG. 1 is a sized block diagram showing the overall configuration of the present invention. Figures 2 to 10 show embodiments of the present invention, with Figure 2 being a schematic perspective view showing the overall configuration of the steering device, Figure 3 being an enlarged longitudinal sectional side view of the variable transmission pressure device, and Figure 4.5. is the third
FIG. 6 is a block diagram showing the configuration of the controller, FIG. 7 is a characteristic diagram of image production by the controller,
FIG. 8.9 is a flowchart showing the failure determination operation of the controller and the operation when a failure occurs, and FIG. 10 is a flowchart showing another example of the operation when a failure occurs. Further, FIG. 11 is a schematic diagram showing the configuration of a conventional vehicle speed sensitive steering device. DESCRIPTION OF SYMBOLS 1... Steering device, 2... Steering handle, 6... Wheels, 10... Transmission ratio variable means, 11
...Controller, 12...Vehicle speed sensor, 26...
- Two control means (control amount calculation section)...Failure detection means (vehicle speed sensor failure detection section).

Claims (1)

[Claims] (1) A transmission ratio variable means that changes the transmission ratio of the wheel steering angle to the steering wheel steering angle in accordance with the output signal of the vehicle speed sensor is interposed in the steering force transmission path that turns the wheels in accordance with the steering of the steering wheel. A steering device for an automobile, comprising: failure detection means for detecting a failure of the vehicle speed sensor, and fixing the transmission ratio to a predetermined setting value when the failure detection means detects a failure of the vehicle speed sensor; A steering device for an automobile, comprising: a control means for making the transition to the set value at different timings when a vehicle speed sensor fails in a high speed range and when a vehicle speed sensor fails in a low speed range.