JPH0717204B2 - 4-wheel steering system for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a vehicle having safety measures against transient phenomena.
The present invention relates to a wheel steering device.

[Prior art]

BACKGROUND ART Conventionally, a four-wheel steering system for a vehicle such as an automobile has a control section for electrically controlling a rear wheel steering mechanism, and depending on whether the L terminal voltage of an alternator is a predetermined value or more or a predetermined value or less, The control unit is operated or stopped.

[Problems to be Solved by the Invention]

However, since the L terminal voltage of the alternator fluctuates according to the engine speed, in the above conventional structure,
When the L terminal voltage of the alternator fluctuates near the above predetermined value, the control section is frequently operated and stopped. Therefore, the rear wheels are steered suddenly, or the steering of the rear wheels is suddenly stopped, so that the stability and safety of steering are lowered, and improvement is required in this respect.

The present invention has been made in consideration of the above-mentioned conventional circumstances, and controls the rear wheel steering mechanism even when the output voltage of the alternator fluctuates and no abnormality occurs in the power supply system. Of the four-wheel steering system for a vehicle, in which the stability and the safety of steering are improved by operating the control unit without stopping and stopping the operation of the control unit only when an abnormality occurs in the power supply system. It is intended to be provided.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, a four-wheel steering system for a vehicle according to the present invention is a four-wheel steering system for a vehicle having a control section for electrically controlling a rear wheel steering mechanism, and supplies electric power to the control section. Output voltage monitor that monitors the output voltage of the alternator that charges the power source and detects that the output voltage is higher than a first predetermined value and lower than a second predetermined value that is smaller than the first predetermined value. The control unit has an operating state when the output voltage monitoring unit detects that the output voltage of the alternator is higher than the first predetermined value, and then the output voltage monitoring unit outputs the output of the alternator. It is characterized in that the operation is stopped when it is detected that the voltage becomes lower than the second predetermined value.

[Action]

According to the above configuration, when the output voltage monitoring means detects that the output voltage of the alternator has become higher than the first predetermined value and the control unit is once actuated, thereafter, due to a change in the engine speed or the like. Even if the output voltage of the alternator fluctuates and becomes lower than the first predetermined value, the operation of the control unit is not stopped until the output voltage of the alternator becomes lower than the second predetermined value. The operation of the control unit is stopped only when it is detected that the voltage becomes lower than the second predetermined value.

Therefore, the output voltage of the alternator fluctuates between the first predetermined value, which is the threshold value for operating the control unit, and the second predetermined value, which is the threshold value for stopping the operation of the control unit, due to changes in the engine speed and the like. By setting the value larger than the fluctuation range and setting the second predetermined value to a low value as indicated when an abnormality occurs in the power supply system due to engine stop or the belt driven by the alternator being cut, It is possible to accurately detect that an abnormality has occurred in the system and stop the operation of the control unit only in that case. As a result, unlike the conventional case, when the output voltage of the alternator fluctuates, the control section is not frequently activated and deactivated, and steering stability and safety can be improved.

The first predetermined value, which is the threshold value for starting the operation of the control unit, is preferably set as high as possible in order to start the operation of the control unit after the power supply voltage is stabilized after the engine is started. .

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

As shown in FIG. 2, the front wheel steering device 1 is configured to transmit the rotation of the steering wheel 3 to the left and right front wheels 2 via a rack and pinion mechanism 4, left and right tie rods 5, and a knuckle arm 6. .

The rear wheel steering device 7 controls the rotation of the stepping motor 25 corresponding to the control signal from the controller 28 by controlling the pair of bevel gears 23 and 24, the control valve 18, and the pinion shaft.
12, the rear wheel steering rod 9, the pair of left and right tie rods 10, and the pair of left and right knuckle arms 11 to transmit to the left and right rear wheels 8, thereby controlling the steering direction of the rear wheel steering device 7. is doing. Controller 28 above
Is connected to an electric motor 21 for driving a hydraulic pump 22, and the hydraulic pump 22 is connected to each of the power cylinders 15 via oil passages 17 and 17, a control valve 18 and pressure oil passages 16 and 16. It is connected to the pressure oil chamber 15b. Further, the rear wheel steering rod 9 is attached to the piston 15a of the power cylinder 15.
Is fixed, the assist force of the rear wheel steering device 7 and its direction can be controlled. Both pressure oil chambers 15b have solenoid valves 3 that open when an abnormality occurs.
A bias oil passage 38, in which 7 is interposed, communicates with each other, and a spring 39 for returning the piston 15a to the neutral position is inserted in both pressure oil chambers 15b.

The controller 28 receives signals from a front wheel steering angle sensor 26 that detects the steering angle of the front wheels 2 and a vehicle speed sensor 27 that detects the vehicle speed, and also supplies a battery 33 that is a power source.
The driving terminal is supplied with driving power and is connected to the L terminal 43 of the alternator for charging the battery 33.

As shown in FIG. 1, in the controller 28,
The driving power from the battery 33 is input to the CPU 44, which is the control unit, via the 5V constant voltage circuit 47. The L terminal 43 of the alternator is connected to the output voltage monitoring means 48. The output voltage monitoring means 48 is composed of comparators 45 and 46, and the L terminal 43 of the alternator is + of the comparator 45.
It is connected to the terminal and one terminal of the comparator 46. Furthermore,
The + terminal of the comparator 46 has an off level value (second predetermined value) (α−) so that the − terminal of the comparator 45 has a potential of (α + β) V which is an on level value (first predetermined value). β) V potential. A drive power source is connected to both comparators 45 and 46, and output terminals of both comparators 45 and 46 are connected to the CPU 44.

In the above configuration, when the engine is started, the L terminal voltage L _x of the alternator rises, but when the engine is stopped, the high level signal from the comparator 46 to the CPU 44 [L terminal voltage L _{x of} alternator L _x ≤ (α-β ) V] is input, the CPU 44 stores it as being lower than the off level, as shown in FIG. 3, and keeps it higher than the on level [L terminal voltage L _x ≧ (α + β) V] of the alternator. CPU44
Is not activated. That is, the L terminal voltage L _{x of the} alternator
Is higher than (α−β) V, the comparator 46 outputs a low level signal to the CPU 44 instead of a high level signal, but the comparator 45 still outputs a low level signal. Although the CPU 44 is not operated, when the L terminal voltage L _x of the alternator becomes (α + β) V or more, a high level signal is output from the comparator 45 to the CPU 44, so that the CPU 44 is operated for the first time.

Next, as described above, once the high level signal from the comparator 45 is input to the CPU 44, it is stored in the CPU 44 as being higher than the ON level.
The CPU 44 is not stopped until the terminal voltage L _x ≦ (α−β) V] or less. That is, the L terminal voltage L of the alternator
_{When x} becomes (α + β) V or less, the comparator 45 changes to a high level signal and outputs a low level signal to the CPU 44, but the comparator 46 still outputs a low level signal to the CPU 44. Is not stopped and the high-level signal is output from the comparator 46 to the CPU 44 when the L terminal voltage L _x of the alternator becomes (α-β) V or less, so that the CPU 44 is stopped for the first time.

Thereby, as shown in FIG. 4, when the L terminal voltage L _x of the alternator fluctuates within a predetermined width [(2β) V], the CPU 44 is prevented from operating or stopping. You can

Here, the off-level value (α-β) V is set to the CPU4 only when the engine is completely stopped or the power supply system is abnormal due to a belt break or the like driving the alternator.
4 is set to a low value so that it will stop operating when an abnormality occurs in the power supply system. On the other hand, at (α + β) V, which is the on-level value, the engine starts completely,
Since it is desirable that the CPU 44 operates after the voltage of the battery 33, which is the driving power source of the CPU 44, stabilizes, it is set as high as possible.

[Effects of the Invention] As described above, the four-wheel steering system for a vehicle of the present invention monitors the output voltage of the alternator that charges the power supply for supplying power to the control unit, and the output voltage becomes higher than the first predetermined value. thing,
And an output voltage monitoring unit that detects that the output voltage is lower than a second predetermined value that is smaller than the first predetermined value, and the control unit causes the output voltage monitoring unit to output the alternator output voltage lower than the first predetermined value. When it is detected that the voltage has become higher, the operating state is set, and thereafter, when it is detected that the output voltage of the alternator is lower than the second predetermined value by the output voltage monitoring means, the operation is stopped.

As a result, the output voltage of the alternator fluctuates between the first predetermined value, which is the threshold value for operating the control unit, and the second predetermined value, which is the threshold value for stopping the operation of the control unit, due to changes in the engine speed or the like. By setting the second predetermined value to a low value as shown when an abnormality occurs in the power supply system due to engine stop or breakage of the belt driven by the alternator, It is possible to accurately detect that an abnormality has occurred in the power supply system and stop the operation of the control unit only in that case. As a result, when the output voltage of the alternator fluctuates as in the conventional case, the control unit is not frequently activated and deactivated, and steering stability and safety can be improved. Play.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main part of a four-wheel steering system for a vehicle according to an embodiment of the present invention, FIG. 2 is an overall schematic configuration diagram of the vehicle, and FIG. 3 is an on-level and a control for operating a control section. FIG. 4 is a graph showing the off level at which the part stops operating, and FIG. 4 is a graph showing the relationship between the alternator L terminal voltage and the time t when the engine is started. In the figure, 7 is a rear wheel steering mechanism (rear wheel steering device), 28
Is a controller, 33 is a battery, 43 is an L terminal of an alternator, 44 is a CPU (control unit), 45 and 46 are comparators, and 48 is output voltage monitoring means.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B62D 137: 00

Claims (1)

[Claims] 1. A four-wheel steering system for a vehicle having a control section for electrically controlling a rear wheel steering mechanism, wherein the output voltage of an alternator for charging a power supply for supplying power to the control section is monitored and the output voltage is The output voltage monitoring means includes means for detecting that the voltage is higher than the first predetermined value and lower than the second predetermined value that is smaller than the first predetermined value. When it is detected that the output voltage of the alternator is higher than the first predetermined value, the operation state is established, and thereafter, when the output voltage monitoring means detects that the output voltage of the alternator is lower than the second predetermined value. A four-wheel steering system for a vehicle, which is in a deactivated state.