JP3097708B2 - Power steering control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering control device for adjusting a steering assist force using a linear solenoid, and more particularly to a power steering control device provided with a circuit for troubleshooting.

[0002]

2. Description of the Related Art For example, in a vehicle speed-sensitive power steering control device, a current supplied to a linear solenoid for adjusting the auxiliary steering force is controlled in a closed loop so that the auxiliary steering force has a value corresponding to the vehicle speed. That is, an error signal is output from the vehicle speed signal and the conduction current detection signal of the linear solenoid,
The current supplied to the linear solenoid is controlled so that this error signal becomes zero.

In the above control circuit, if the wiring of the path for detecting the energizing current is grounded, an accurate energizing current detection signal cannot be detected, and the steering assist force may fluctuate rapidly due to an erroneous error signal. The problem arises.

In order to solve the above problem, an apparatus disclosed in Japanese Patent Application Laid-Open No. 60-234070 has been proposed. This apparatus focuses on the fact that when the wiring of the path for detecting the energizing current is grounded, the energizing current detection signal becomes zero and the error signal becomes extremely large. In other words, the error signal is compared with the reference value in the control circuit, and when the error signal becomes larger than the reference value, it is determined that the wiring of the path for detecting the conduction current is grounded, and the backup circuit is activated to close the loop. Switch from control to open loop control.

[0005]

In such a known device, at the moment when the ignition switch is turned on, the current does not flow through the linear solenoid immediately due to the load drive circuit being turned off and a transient phenomenon, so that the current detection signal is zero. However, there is a problem that the backup circuit is erroneously operated and the open loop control is performed even though the wiring of the path for detecting the conduction current is not grounded. In addition, when a certain period of time elapses in the open loop control, a current flows through the linear solenoid, and the energization current detection signal is detected. However, the energization current detection signal changes with a change in the battery voltage or the inductance of the linear solenoid. Therefore, the vehicle speed signal and the energization current detection signal do not match, the error signal does not become lower than the reference value, the open loop control continues, and there is a possibility that the auxiliary steering force does not become an appropriate value corresponding to the vehicle speed.

Therefore, the present invention has been made in view of the above-mentioned problem, and even at the moment when the ignition switch is turned on, it is not necessary to determine that the path for detecting the conduction current is erroneously grounded. An object is to provide a power steering control device capable of starting control.

[0007]

In order to achieve the above object, a power steering control device according to the present invention comprises a linear solenoid for adjusting a steering assist force, and an actual steering assist force adjusted by the linear solenoid. Detection signal output means for outputting a detection signal corresponding to the target signal, target signal output means for outputting a target signal corresponding to a target steering assist force of the steering according to a traveling state of the vehicle, the target signal and the target signal Control signal output means for outputting a control signal based on an error from the detection signal so that the actual auxiliary steering force approaches the target auxiliary steering force; and a control signal output by the control signal output means as a reference value. Control signal comparing means for comparing with the detection signal when the control signal is larger than a reference value by the control signal comparing means. Not be a backup means for outputting a control signal based only on the target signal, a boosting means for boosting said detection signal immediately after the ignition switch to the ON state, in that it comprises the gist thereof.

[0008]

According to the above configuration, immediately after the ignition switch is turned on, the booster temporarily boosts the detection signal output by the detection signal output.
The control signal output by the control signal output means is small and never larger than the reference value. Therefore, immediately after the ignition switch is turned on, normal closed-loop control is started without erroneously determining that the path for detecting the supplied current is grounded.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. In FIG. 1 showing the first embodiment of the present invention, reference numeral 1 denotes a sensor, and 2 denotes a reference voltage characteristic generating circuit. The sensor 1 is, for example, a vehicle speed sensor, and the reference voltage characteristic generating circuit 2 generates an adjustment voltage that changes according to the vehicle speed.

Reference numeral 3 denotes an error amplification circuit, 4 denotes a comparison circuit, and 5 denotes a triangular wave oscillation circuit. The control signal appearing at the output of the comparison circuit 4 is applied to the load drive circuit 6 via the selection circuit 12. The load drive circuit 6 is connected to a vehicle battery,
A current having a magnitude corresponding to the control signal from the selection circuit 12 is supplied to the linear solenoid 7 as an auxiliary force generating member. The linear solenoid 7 changes the opening degree of the valve, which is changed by bypassing the supply flow rate from a pump (not shown) to the power steering gear box, in accordance with the magnitude of the supply current, similarly to a known type. The steering assist force is adjusted accordingly.

The ground side of the linear solenoid 7 is connected to the vehicle body ground via a current cable, and a resistor (voltage effect element) 8 for current-voltage change is inserted and connected in the line, and is generated in the resistor 8. The voltage signal is amplified via the amplifier circuit 9 and supplied to the error amplifier circuit 3 as a measurement voltage.

The input side of the amplifier circuit 9 is connected to an initial voltage circuit 14. FIG. 2 shows a configuration diagram of the initial voltage circuit 14. The initial voltage circuit 14 includes a differentiating circuit having a certain time constant. The constant voltage diode 17 is connected to the capacitor 15 and the constant voltage diode 17 so that the voltage supplied to the capacitor 15 and the resistor 16 constituting the differentiating circuit is constant. It is connected in parallel with the resistor 16. The input side is connected to a battery via an ignition switch 18.

Therefore, the ignition switch 18
When turned on, the differentiating circuit includes a constant voltage diode 17.
Constant voltage signal V determined by_AIs supplied. And fine
The output voltage waveform from the dividing circuit is as shown in FIG. Figure
As is apparent from FIG. 3, the output voltage is
At the moment when the switch 18 is turned on, the output voltage = V _A
, But decreases with time due to the characteristics of the differentiating circuit.
After a certain period of time, it becomes substantially zero. Note that the voltage signal V
_AAnd the adjustment voltage value when the vehicle speed is zero is output by the error amplifier circuit 3.
The voltage signal V is adjusted so that the error-amplified value does not exceed the reference voltage.
_AIs set.

The selection circuit 12 is normally in a state of selecting an input so as to apply the output signal of the comparison circuit 4 to the load driving circuit 6. At this time, the error amplification circuit 3, the comparison circuit 4, the oscillation circuit 5, the power supply circuit 6, the resistor 8, and the amplification circuit 9
The supply current of the linear solenoid 7 is reduced in order to reduce the auxiliary force in response to the increase in the vehicle speed. Then, feedback control is performed so that the supply current becomes a value corresponding to the vehicle speed (so that the supply current is decreased by increasing the measured supply current and the supply current is decreased by decreasing the measured supply current).

More specifically, the output voltage of the error amplifying circuit 3 changes in a direction to increase the relative difference between the adjustment signal and the measurement signal (for example, to a large value) as the vehicle speed increases. When the supply current to the solenoid 7 increases and the measurement signal increases, the output voltage of the error amplifier circuit 3 changes in a direction in which the relative difference decreases, and is stabilized in an appropriate balance state.

In the comparison circuit 4, the output voltage of the error amplification circuit 3 is compared with the triangular wave voltage of the oscillation circuit 5. The triangular wave voltage has a constant cycle and a constant wave height, and a pulse train signal having a duty ratio corresponding to the magnitude of the output voltage of the error amplifier circuit 3 appears at the output of the comparison circuit 4.

When this pulse train signal is applied to the load drive circuit 6 via the selection circuit 12, the load drive circuit 6 turns on / off the linear solenoid 7 in accordance with the on / off of the pulse train signal. Although the linear solenoid 7 is energized intermittently, the opening of the valve is adjusted to correspond to the average value of the supply current because the cycle of the triangular wave voltage is selected to be sufficiently short. Thus, the steering assist force is accurately controlled according to the adjustment signal such as the vehicle speed.

According to the present invention, the selection circuit 12
The circuit is controlled by a circuit for detecting an abnormality indicated by 0 or 11, and when an abnormality is detected, the input is cut off from the comparison circuit 4 and connected to a backup circuit indicated by reference numeral 13.

Reference numeral 10 denotes a reference voltage generation circuit for generating a reference voltage for the output voltage of the error amplifier circuit 3, which is composed of a voltage dividing resistor or the like. The magnitude of the reference voltage is set in advance so that the relative difference between the adjustment signal represented by the output voltage and the measurement signal corresponds to the lowest value representing the abnormal state. In the embodiment, the magnitude of the reference voltage is set to a value obtained by adding a predetermined value to the adjustment signal.

The reference voltage is compared with the actual output voltage of the error amplifier circuit 3 in the comparison circuit 11, and when the output voltage exceeds the reference voltage, a command signal is given to the selection circuit 12 to input the backup circuit 13 to the input. Connect. Therefore, as shown in FIG. 4, for example, the selection circuit 12 includes two gates 12A and 12B which are opened complementarily.

The backup circuit 13 is configured as a comparison circuit for comparing the adjustment voltage of the reference voltage characteristic generation circuit 2 with the triangular wave voltage of the triangular wave oscillation circuit 5. Therefore, a pulse train signal whose duty ratio corresponds to only the adjustment voltage and does not depend on the measurement voltage appears in the output of the backup circuit 13.

When the selection circuit 12 selects the backup circuit 13, the current supplied to the linear solenoid 7 changes according to the adjustment voltage. The operation of this device will be briefly described. First, when the current flowing through the linear solenoid 7 is feedback-controlled to a normal value corresponding to the vehicle speed, the output voltage of the error amplifier circuit 3 becomes the adjustment signal and the measurement signal. The selection circuit 12 maintains the state in which the output of the comparison circuit 4 is selected as the input by the comparison circuit 11 because the comparison circuit 11 does not indicate an abnormality in the relative difference.

If the ground line of the linear solenoid 7 is grounded without passing through the resistor 8 during the feedback control, the measured voltage generated by the amplifier circuit 9 is equal to the value when the supply current of the linear solenoid 7 is zero. Become. For this reason, the output voltage of the error amplifier circuit 3 changes in a direction to increase the supply current, and as a result, the maximum current is continuously supplied to the linear solenoid 7.

At this time, the comparison circuit 11 according to the present invention switches the selection circuit 12 to the input from the backup circuit 13, so that the feedback control is stopped at this time. Instead, the backup circuit 13 works to determine the supply current to the linear solenoid 7 according to the adjustment voltage from the reference voltage characteristic generation circuit 2. Thus,
The device is switched from the closed loop control to the open loop control, and the steering assist force does not fluctuate rapidly and continues to be controlled according to conditions such as the vehicle speed.

Now, consider the operation at the moment when the ignition switch 18 is turned on in FIG. 1. Does not flow through the resistor 8, no voltage is immediately generated in the resistor 8,
No voltage signal is input from the resistor 8 to the amplifier circuit 9.
Therefore, even if the ground line of the linear solenoid 7 does not fall through the ground without passing through the resistor 8, the measured voltage is not output from the amplifier circuit 9.

On the other hand, a voltage signal _VA is supplied to a differentiating circuit in the initial voltage circuit 14, and the voltage signal _VA is amplified via the amplifier circuit 9 and output to the error amplifier circuit 3.
Since the value obtained by error-amplifying the voltage signal _VA and the adjustment voltage value when the vehicle speed is zero by the error amplifier circuit 3 does not exceed the reference voltage,
The comparison circuit 11 does not switch the selection circuit 12 to the input from the backup circuit 13, and performs closed loop control according to the vehicle speed.

Even when the ground line of the linear solenoid 7 is actually grounded without passing through the resistor 8, the time during which the initial voltage circuit 14 outputs a voltage is several tens of milliseconds. After several tens of milliseconds after the switch 18 is turned on, the comparison circuit 11 switches the selection circuit 12 to the input from the backup circuit 13 so that open loop control can be performed.

In this embodiment, the resistor 8 corresponds to the detection signal output means, the reference voltage characteristic generating circuit 2 corresponds to the target signal output means, the error amplifier circuit 3 corresponds to the control signal output means, The backup circuit 13 corresponds to backup means, and the initial voltage circuit 14 corresponds to boost means.

In the device of the embodiment described above, it is easy to modify the details of the circuit means without departing from the scope of the present invention. For example, as shown in FIG. 5 and FIG.
In this embodiment, the details of the position and role of the selection circuit 12 are changed. That is, the selection circuit 12 is arranged between the output of the error amplification circuit 3 and the input of the comparison circuit 4, and selects the output voltage of the error amplification circuit 12 and the adjustment voltage of the reference voltage characteristic generation circuit 2. Therefore, the circuit is configured using, for example, two analog gates 12C and 12D.

Further, in the first and second embodiments, a signal indicating the detection of an abnormality in the comparison circuit 11 is additionally guided to the reference voltage characteristic generating circuit 2 to correct the adjustment voltage when the abnormality is detected. You may make it.

For example, as shown in FIG. 7, by connecting a normally closed switch responsive to the detection signal from the comparison circuit 11 in parallel with one of the divided voltage and low voltage, the adjustment voltage is reduced in a decreasing direction at a constant ratio. Can be corrected.

Further, even if the initial voltage generating circuit 14 is provided between the amplifying circuit 9 and the error amplifying circuit 3, the same effect as in the above embodiment can be obtained. In practicing the present invention, the invention is not limited to the mode described in the description of the above-described embodiment, but may be implemented within the scope of the claims, if necessary, in the description of the outline of the configuration of the invention. Embodiments can be modified with reference to matters.

Furthermore, it is free to combine the reference voltage characteristic generating circuit 2 with, for example, a steering angle sensor other than the vehicle speed sensor so that the adjustment voltage is also changed by the steering angle or the like.

[0034]

As described above in detail, the power steering control device according to the present invention is provided with the boosting means for boosting the detection signal corresponding to the actual steering assist force immediately after turning on the ignition switch. Therefore, the open-loop control is not performed immediately after the backup means malfunctions and the ignition switch is turned on,
There is an excellent effect that the closed loop control can be performed immediately after the ignition switch is turned on.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram of an initial voltage generation circuit 14.

FIG. 3 is an output voltage waveform from an initial voltage generation circuit 14;

FIG. 4 is an electrical connection diagram showing details of a main part of FIG. 1;

FIG. 5 is a block diagram showing a second embodiment of the present invention.

6 is an electrical connection diagram showing details of a main part of FIG. 5;

FIG. 7 is an electrical connection diagram showing an additional modification in the first or second embodiment.

[Explanation of symbols]

 2 Reference voltage characteristic generation circuit 3 Error amplification circuit 7 Linear solenoid 8 Resistance 11 Comparison circuit 13 Backup circuit

Continuation of the front page (56) References JP-A-62-268775 (JP, A) JP-A-62-234783 (JP, A) JP-A-63-41280 (JP, A) JP-A-60-234070 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B62D 6/00-6/04 B62D 5/00-5/30

Claims (1)

(57) [Claims] 1. A linear solenoid for adjusting a steering assist force of a steering, a detection signal output means for outputting a detection signal corresponding to an actual steering assist force adjusted by the linear solenoid, and according to a traveling state of the vehicle. A target signal output means for outputting a target signal corresponding to a target steering assist force of the steering; and an actual assist steering force based on an error between the target signal and the detection signal. Control signal output means for outputting a control signal to approach the control signal; control signal comparison means for comparing the control signal output by the control signal output means with a reference value; and the control signal being a reference value by the control signal comparison means. A backup means for outputting a control signal based on only the target signal regardless of the detection signal; Power boosting means for boosting the detection signal immediately after turning on the ignition switch.