JPS6341280A - Power steering control device - Google Patents

Abstract

PURPOSE:To prevent production of a fluctuation in a steering force and to improve steering performance, by a method wherein, even when the source voltage of an actuator for varying a steering force is fluctuated, a fluctuation in a drive current due to a fluctuation in the source voltege is prevented from production. CONSTITUTION:When abnormality occurs to a measuring means 3 due to short- circuit of a wire harness outputting a measuring signal from a measuring means 3 to an error amplifying circuit 24, a backup means 7 is switched from an output signal from the error amplifying circuit 24 to an output signal from a regulating signal generating means 4. When abnormality on the measuring means 3 is detected, a regulating signal from the regulating signal generating means 4 is applied on a voltage duty ratio converting circuit 14 of a feed circuit 2 to control the drive current of a solenoid 11. Further, through correction of a pulse train signal, on which duty ratio control is applied according to a car speed, so that a duty ratio is varied based on a change in a source voltage by means of a correcting means 10, the influence can be prevented from being exercised by a fluctuation in a source voltage.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a power steering control device, and in particular,
The present invention relates to an improvement of a power steering control device that changes steering force according to vehicle speed.

[Conventional technology]

Conventionally, in automobile power steering control devices,
In order to ensure an appropriate steering force depending on the vehicle speed, a vehicle speed sensitive type is provided that is equipped with a control computer that controls a variable steering force actuator, such as a near solenoid valve, in response to a signal from a vehicle speed sensor. . An example of such a vehicle speed sensitive power steering control device is disclosed in Japanese Patent Laid-Open No. 60-234070. As shown in FIG. 5, this power steering control device includes a steering force variable actuator 1 that receives a current signal and generates a steering force corresponding to the current signal.
and a power supply means that receives a control signal and supplies the current signal of a magnitude corresponding to the control signal to the variable steering force actuator 1 in order to adjust the steering force generated by the variable steering force actuator 1. 2, a measuring means 3 that monitors the drive current by generating a measurement signal corresponding to the actual magnitude of the current signal supplied to the steering force variable actuator 1, and a measuring means 3 that monitors the drive current, and adjusts the steering force according to the vehicle speed. adjustment signal generating means 4 for generating an adjustment signal for the purpose of adjusting the steering force; adjustment means 5 comprising an error amplification circuit that applies the control signal of 1 to the power supply means 2; and the relative relationship between the measurement signal from the measurement means 3 and the 1-control signal from the adjustment means 5 is set in advance. detecting means 6 for detecting a failure of the measuring means 3 by detecting that the relative relationship is outside the set range; 3, and the control signal for reducing the steering force by 110 is applied to the power supply means 2 in response to the adjustment signal from the adjustment signal generation means 4.
and a backup means 7 for providing data to the computer. The adjustment signal generating means 4 includes a vehicle speed sensor 4Δ and a vehicle speed-voltage conversion circuit 4B that converts the output signal of the vehicle speed sensor 4A into a voltage signal corresponding to the vehicle speed. The power supply means 2 includes a voltage-duty ratio conversion circuit 2A that converts a control signal, which is a voltage signal, from the adjustment means 5 or the adjustment signal generation means 4 into a pulse train signal whose duty ratio is controlled, Conversion circuit 2
A triangular wave oscillator 2B that gives a triangular wave to A, and the voltage -
It is comprised of a drive circuit 2C that outputs a current signal for the steering force variable actuator 1 in response to a duty ratio-controlled pulse train signal from the duty ratio variable circuit 2A. According to this power steering control OFF device, normally the adjustment signal corresponding to the vehicle speed from the adjustment signal generating means 4 is added to the measuring means 3 as a load current feedback signal.
Correction is applied using the measured signal to eliminate fluctuations in the power supply voltage. Thereby, it is possible to perform steering force control in accordance with the vehicle speed with high precision. Further, if the feedback signal wire harness from the measuring means 3 is short-circuited and the signal cannot be obtained, an abnormality in the measuring means 3 is detected, and when this abnormality is detected, the backup means 7 is activated. , adjustment signal generating means 4
outputting a voltage signal corresponding to the vehicle speed to the power supply means 2;
Based on this, feedforward control is performed in which the steering force variable actuator 1 is controlled in a III manner. Therefore, even when an abnormality is detected in the measuring means 3, steering force controllability corresponding to the vehicle speed can be ensured to some extent, and sudden changes in the steering force can be prevented. In this manner, when an abnormality in the measuring means 3 is detected and a feedback signal cannot be obtained, the backup means 7 switches from feedback control to feedforward control. [Problems to be Solved by the Invention] However, when the power supply voltage of the power supply means 2 that drives the variable steering force actuator 1 changes during this feedforward control, the variable steering force actuator 1 changes.
The drive current varies in proportion to the variation in the power supply voltage of the power supply means 2. That is, the drive current of the variable steering force actuator 1 is obtained by applying a drive voltage whose duty ratio is controlled to the load. Therefore, the steering force variable actuator 1
There is a proportional relationship between the drive current, the product of the duty ratio, the power supply voltage, and the constant A. As a result, during the feedforward control, the duty ratio is uniquely determined by the vehicle speed, so the drive current of the variable steering force actuator 1 changes approximately in proportion to the change in the power supply voltage. This fluctuation in drive current is caused by the steering force variable actuator 1.
This is a range that the driver can experience as a change in the steering force through the steering force, which poses a problem in terms of vehicle operation. Further, during feedback control by the measuring means 3, if the feedback signal from the measuring means 3 cannot be obtained due to a short circuit in the wire harness or the like,
This needs to be detected as described above. Conventionally, an abnormality in the measuring means 3 is detected by determining that an abnormality has occurred in the measuring means 3 when the output of the adjusting means 5 exceeds a constant value corresponding to the vehicle speed. The output signal of the adjustment means 5, which is the subject of judgment in this abnormality detection, includes a set voltage signal corresponding to the vehicle speed from the adjustment signal generation means 4, a power supply voltage correction value of the power supply means 2, and a steering force variable actuator. This includes the load fluctuation correction value of 1. That is, the set voltage signal from the adjustment signal generating means 4, added and subtracted by the power supply voltage correction value and the load fluctuation correction value, becomes the output signal of the adjustment means 5, which is the target of the abnormality detection determination. Therefore, in the conventional abnormality detection of the measuring means 3, the output signal from the vA node means 5, which is the object of abnormality detection judgment, contains uncertain elements such as the power supply voltage correction value and the load fluctuation correction value, as described above. Therefore, as shown in FIG. 6, an uncertainty region B corresponding to each of the above correction values must be set for the adjustment signal A, which is the set voltage corresponding to the vehicle speed.

This allows the distance from the adjustment signal A to be set by the correction valve (uncertain area B) when setting the abnormality detection level C of the measuring means 3.
vertical distance) or more. Therefore, there is a problem in that the accuracy of abnormality detection by the measuring means 3 is reduced due to the uncertainty region B due to each correction value. As a result, an overcurrent momentarily flows through the steering force variable actuator 1 when the measuring means 3 is abnormal, or an overcurrent constantly flows through the steering force variable actuator 1 when the feedback signal slightly leaks. There is a possibility that phenomena such as As a result, there is a problem in that when the measuring means 3 is abnormal, the steering force suddenly changes, giving a sense of discomfort to the driver. [Object of the Invention] The present invention has been made in view of the above-mentioned conventional problems, and it is possible to reduce fluctuations in steering force even when the power supply voltage of a variable steering force actuator fluctuates, and to improve feedback control. It is an object of the present invention to provide a power steering control device that can improve the accuracy of abnormality detection of the measuring element stage 3.

[Means to solve the problem]

The present invention converts a voltage signal corresponding to vehicle speed into a pulse train signal whose duty ratio is controlled by a voltage-duty ratio conversion circuit, applies this pulse train signal to a drive circuit, and causes the drive circuit to drive a drive current of an actuator for variable steering force. In the power steering control device that changes the steering force according to the vehicle speed by changing the power supply voltage, the duty ratio of the pulse train signal is changed based on the change in the power supply voltage supplied to the drive circuit to reduce the influence of fluctuations in the electric voltage. The above object is achieved by providing a correction means for eliminating the problem.

[Effect]

In the present invention, when converting a voltage signal according to vehicle speed into a pulse train signal whose duty ratio is controlled, the duty ratio of the pulse train signal is adjusted based on a change in the power supply voltage supplied to a drive circuit that drives a variable steering force actuator. is changed to eliminate the effects of power supply voltage fluctuations. Thereby, even if the power supply voltage of the variable steering force actuator fluctuates, the load current of the variable steering actuator can be kept constant. Therefore, even if an abnormality occurs in the measuring means and feedback control based on the measurement signal of the measuring means is not performed, and even if the power supply voltage of the drive circuit that supplies power to the variable steering force actuator fluctuates, , it is possible to reduce fluctuations in steering force due to fluctuations in the power supply voltage. Furthermore, by correcting the pulse train signal whose duty ratio is controlled to reflect changes in the power supply voltage, it is possible to improve the abnormality detection accuracy of the measuring means. That is, the determination for detecting abnormality in the measuring means is performed as described above. This is based on the output of the J11i$ means, and the output signal of this adjusting means is
As shown in FIG. 4, the power supply voltage correction value is canceled by the correction means. Therefore, the uncertainty area B shown in FIG. 6 is only for the load fluctuation correction m, and the new uncertainty area has a shorter vertical distance than the conventional uncertainty area. The area can be made smaller. As a result, a new abnormality detection level E,
The abnormality detection level C can be set to a smaller value than the conventional abnormality detection level C, and the accuracy of abnormality detection by the measuring means can be improved.

【Example】

Examples of the present invention will be described below with reference to the oral surface. In this embodiment, the same components as those in the conventional device configuration are given the same reference numerals, and the explanation thereof will be omitted. As shown in FIGS. 1 to 3, this embodiment includes a variable steering force actuator 1 that receives a current signal and generates a steering force corresponding to the current signal, and a variable steering force actuator 1 that receives a current signal and generates a steering force corresponding to the current signal. a power supply means 2 for receiving a control signal and supplying the current signal having a size corresponding to the control signal to the steering force variable actuator 1 in order to adjust the generated steering force; and the steering force variable actuator 1 measuring means 3 for generating a measuring signal corresponding to the actual magnitude of said current signal supplied to said measuring means; adjusting signal generating means 4 for generating an adjusting signal for adjusting the steering force in accordance with the vehicle speed; adjusting means 5 for applying the control signal to the power supply means for adjusting the steering force in accordance with the relative relationship between the measurement signal by the means 3 and the adjustment signal by the adjustment signal generating means 4; a detecting means 6 for detecting that the relative relationship between the measurement signal by the measuring means 3 and the control signal by the adjusting means 5 is outside a preset range; In response to being out of the set range, the measurement signal from the measurement means 3 is invalidated, and the control signal for adjusting the steering force corresponds to the adjustment signal from the adjustment signal generation means 4. and a correction means 10 for correcting the control signal of the adjustment means 5 based on a change in the voltage '8T1 supplied to the power supply means 2. Specifically, the variable steering force actuator 1 includes a near solenoid valve 11 that adjusts the opening of a bypass passage that communicates both cylinder chambers of a steering gear box (not shown). The power supply means 2 includes a drive circuit 12 made of a power transistor, and a voltage duty ratio conversion circuit 14 that applies a control signal to the drive circuit 12. The measuring means 3 includes a resistor (voltage drop element) 16 for current-to-voltage conversion provided on the ground side of the linear solenoid valve 11, and an amplifier circuit 18 for amplifying the voltage signal generated at the resistor 16. ing. Specifically, the adjustment signal generating means 4 includes a vehicle speed sensor 20 that detects the vehicle speed, and a vehicle speed-voltage conversion circuit ff! that converts the detection signal from the vehicle speed sensor 20 into frequency and voltage. It is composed of 22. The adjustment means 5 includes an error amplification circuit 24 that inputs the adjustment signal from the vehicle speed-voltage conversion circuit 22 of the adjustment signal generation means 4 and the measurement signal from the amplifier circuit of the measurement means 3 and extracts an error. It consists of The detection means 6 detects the 1i speed of the adjustment signal generation means 4.
A level creation circuit 26 that creates a fail judgment u ltE signal based on the y4rfi signal from the voltage conversion circuit 22
and a fail determination circuit 28 that compares the output signal of the level creation circuit 26 with the output signal of the error amplification circuit 24 of the adjustment means 5 to determine whether the measuring means 3 has failed. The backup means 7 generates an adjustment signal of the vehicle speed-voltage conversion circuit 22 based on the detection result of the detection means 6;
Alternatively, by selecting one of the output signals of the error amplification circuit 24, the voltage-duty conversion circuit 1 of the power supply means 2
It consists of two switching circuits that output to 4. The correction means 10 is composed of a triangular wave oscillator 3o for duty generation, and a voltage conversion circuit 32 as a power source for this oscillator. Specifically, the circuit configuration is as shown in FIG. 2, and is configured to change the peak value of the triangular wave for duty generation in conjunction with the power supply voltage. As shown in FIG. 3, the voltage conversion circuit 32 is set so that the product of the power supply voltage and the duty is always approximately constant for a control signal VF corresponding to a constant vehicle speed. That is, the diagonal lines F, G, ! in the diagram represent the product of power supply voltage and duty. The voltage conversion circuit 32 is set so that -1 has approximately the same area. In addition, the broken line LJ in the figure indicates 'Fi source voltage voltage 1 day 6.12.8
The triangular wave at v is shown in the area ll1-5M, Nh IFx
The duty when the PA voltage is 16.12.8V (7) is shown. Next, the operation of this embodiment will be explained. First, if the entire system is functioning normally, v
The output signal from the vehicle speed sensor 20 of the A-node signal generation means 4 is converted into a voltage signal by the vehicle speed-voltage conversion circuit 22, and the adjustment signal converted to this voltage signal is output to the error amplification circuit 24 of the adjustment means 5. . Further, the drive vJ current of the linear solenoid 11 is taken out as a measurement signal by the resistor 16 and amplifier circuit 18 of the measurement means 3, and this measurement signal is outputted to the error amplifier circuit 24 of the m-node means 5 as a feedback signal. The error amplification circuit 24 outputs a control signal for the power feeding means 2 based on the m-node signal and the measurement signal. In the power feeding means 2, the control signal and the triangular wave reference voltage signal obtained from the triangular wave transmitting circuit of the correction circuit 10 are compared by the voltage-duty ratio conversion circuit 14, and the control signal is converted into a pulse train signal whose duty ratio is controlled; This controls the drive circuit 12. Therefore, linear solenoid 1
1, a drive current that has been corrected for fluctuations in the power supply voltage flows. In this case, the linear solenoid 11 is V-controlled in accordance with the vehicle speed, and a steering force corresponding to the vehicle speed is obtained. Furthermore, if an abnormality occurs in the measuring means 3 due to a short circuit in the wire harness that outputs the measurement signal of the measuring means 3 to the error amplifying circuit 24, the detecting means 6 detects this abnormality and performs a backup. The means 7 is switched from the output signal of the error amplifying circuit 24 to the output signal of the Oi1 node signal generating means 4. As a result, when an abnormality is detected in the measuring means 3, the adjustment signal of the adjustment signal generating means 4 acts on the voltage duty ratio conversion circuit 14 of the power supply circuit 2, and the drive current of the linear solenoid 11 is controlled based on this adjustment signal. become. Moreover, since the pulse train signal whose duty ratio is controlled according to the vehicle speed is corrected by the correction means 10 to change the duty ratio based on the change in the N source voltage, an abnormality occurs in the detection means 3 and current feedback is returned. Even if control becomes impossible, it is possible to eliminate the influence of fluctuations in power supply voltage and prevent the steering force from fluctuating so greatly that it can be felt. Note that when an abnormality is detected in the measuring means 3, the output signal value of the error amplification circuit 24, which is the target of the abnormality detection judgment, is determined by the abnormality of the measuring means 3 because the correction component of the power supply voltage has been eliminated by the correcting means 10. Detection accuracy can be improved. In the above embodiment, the duty ratio of the pulse train is controlled by changing the peak value of the triangular wave in conjunction with fluctuations in the electric WA voltage so as to keep the driving current of the linear solenoid 11 constant even when the power supply voltage fluctuates. When correcting the signal, the peak value is changed by an approximate curve in order to simplify the oscillator power supply section, but the present invention is not limited to this, and the duty ratio is inversely proportional to the power supply voltage. It is also possible to change it by changing it.

【Effect of the invention】

As explained above, according to the present invention, even when the power supply voltage of the variable steering force actuator fluctuates, fluctuations in the drive current based on the fluctuations in the power supply voltage are suppressed, and
This has the excellent effect of suppressing fluctuations in steering force and improving steering performance, and further improving the abnormality detection accuracy of the measuring means.

[Brief explanation of drawings]

FIG. 1 is a block diagram including a partial circuit diagram showing the device configuration of an embodiment of the power steering f, 13 control device according to the present invention, and FIG. 2 shows the configuration of the correction means in the practical example. The circuit diagram shown in FIG. 3 shows the triangular wave peak value in the voltage-duty ratio conversion circuit of the correction means in the same embodiment.
A diagram showing the relationship between the duty and the electric voltage, FIG. 4 is a diagram showing the relationship between the abnormality detection level and the output signal of the adjusting means for detecting an abnormality in the measuring means, and FIG. FIG. 6 is a block diagram showing the device configuration of a conventional power steering control device.
This is a line section showing the relationship between the abnormality detection level of the measuring means and the output signal of the adjusting means in d3 of the iI device. DESCRIPTION OF SYMBOLS 1... Actuator for variable steering force, 2... Power supply means, 3... Measurement means, 4... Adjustment signal generation means, 5... Adjustment means, 6... Detection means,
7... Backup means, 10... Correction means, 12... Drive circuit. Agent Kei Matsuyama Ya Kantaka Theory Figure 2 Figure 3

Claims (1)

[Claims] (1) Convert a voltage signal according to vehicle speed into a pulse train signal whose duty ratio is controlled by a voltage-duty ratio conversion circuit, apply this pulse train signal to a drive circuit, and use the drive circuit to control the drive current of the actuator for variable steering force. In the power steering control device that changes the steering force according to the vehicle speed, the duty ratio of the pulse train signal is changed based on the change in the power supply voltage supplied to the drive circuit to eliminate the influence of fluctuations in the power supply voltage. A power steering control device comprising a correction means.