JPS6154363A - Controller for power steering apparatus - Google Patents

Abstract

PURPOSE:To improve working efficiency by setting the detection sensitivity independently from the number of apparatuses by judging the disconnection of a car-speed sensor circuit when the variation state of the car-speed signal becomes speedy in comparison with the variation state generated in the ordinary traveling. CONSTITUTION:When a car-speed sensor 1 is broken, the output voltage of a voltage conversion circuit 2 sharply increases in comparison with in ordinary traveling. The voltage of the reversal input terminal of a comparator 6b of a disconnection detecting circuit 6 slowly rises, since time constant is large. Therefore, when the voltage of the nonreversal input terminal exceeds the voltage of the reversal input terminal, the circuit 6 supplies an output signal into a control circuit 8. Therefore, the transistor 8l of the control circuit 8 is turned ON, and a relay 8j operates to switch a contact point 8k. Therefore, a solenoid driving circuit 4 is disconnected from a power source, and therefore the driving circuit 4 does not output pulse signals into a solenoid valve. Therefore, the oil supplied into a power steering apparatus reduces, and the necessary steering force increases.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a control device for a power steering device that controls oil flow rate in accordance with vehicle speed.

[Prior art]

Conventionally, a power steering system generates a vehicle speed signal that determines the repetition period of the "l" level and rOJ level in response to the vehicle speed. Therefore, it is possible to perform steering with a small steering force over a wide range of vehicle speeds.

However, if the circuit containing the vehicle speed sensor that generates the vehicle speed signal is disconnected during high-speed driving, the vehicle speed signal cannot be obtained, and the power steering system controls the oil flow to the maximum, so the steering force is reduced to 1. It is dangerous to become smaller than the Buddha. For this reason, conventionally, a current is constantly passed through the vehicle speed sensor circuit, and when this current stops flowing, Mm of the vehicle speed sensor circuit is detected and a safety device is activated.

However, since the vehicle speed signal needs to be supplied not only to the power steering device but also to other devices, many devices are connected to the vehicle speed sensor, which reduces the combined resistance seen from the power steering device. However, conventional power steering devices that monitor the current flowing through the vehicle speed sensor circuit must set detection sensitivity to match this combined resistance, and the number of devices connected to the vehicle speed sensor changes. Since sensitivity settings had to be made each time, the work efficiency during installation was poor.

[Object and structure of the invention]

Therefore, an object of the present invention is to provide a control device for a power steering device that allows detection sensitivity to be set regardless of the number of devices connected to a vehicle speed sensor and improves work efficiency during installation. be.

In order to achieve such an object, the present invention determines that the vehicle speed sensor circuit is disconnected when the vehicle speed signal changes more rapidly than the change state that occurs during normal driving. be.

This invention will be explained in detail below using drawings showing examples. I1
I will explain in 1.

〔Example〕

FIG. 1 is a circuit diagram showing one embodiment of the present invention. In the figure, 1 is a vehicle speed sensor that generates a number of pulse-like electrical signals corresponding to the vehicle speed as a vehicle speed signal, 2 is a voltage conversion circuit that converts the vehicle speed signal into a DC voltage, 3 is an amplifier circuit, 4 is a solenoid drive circuit, and 5 1 is a short-circuit detection circuit that detects a short circuit in the vehicle speed sensor 1; 6 is a disconnection detection circuit that detects a disconnection in the vehicle speed sensor 1; and 7 is a 1171J control that controls oil Kk to a value that allows safe driving when the vehicle speed sensor 1 is short-circuited. A circuit 8 is a control circuit that controls the oil flow rate to a value that allows safe driving when the vehicle speed sensor 1 is disconnected.

The vehicle speed sensor 1 includes a magnet 1a, a coil 1b, and resistors 1c to ie.
, a comparator 1f1, and a transistor 1g, and the magnet 1a rotates together with the speedometer cable. Mixed pressure 511: switching circuit 2 is resistor 2a ~
2d, capacitors 2e to 2g, transistors 2h, and diodes 21 #2j, and generates a DC voltage that decreases as the vehicle speed signal becomes higher speed. The amplifier circuit 3 is designed to amplify the input signal in-phase.

The solenoid drive circuit 4 includes resistors 4a to 40 and a capacitor 4.
It is composed of p~4r, a diode 4S1, a comparator 4t, and transistors 4u and 4v, and generates a pulse signal whose duty ratio decreases as the supplied input signal decreases.

The short circuit detection circuit 5 includes resistors 5a to 5c and diodes 5d and 5.
It is composed of e capacitors 5f, 5g, and a comparator 5h. The disconnection detection circuit 6 includes resistors 6a to 6d, a capacitor 6erGfs, a diode 6gt, and a comparator 6h. The control circuit 7 includes a resistor 7a, a capacitor 7b1, and a transistor 7c. The control circuit 8 includes resistors 8a to 8d, capacitors 8e to 8g, diode 8h, varistor 8i1, relay 8j1 υno 8j
The contact point 8 is composed of one transistor 8t.

Output terminals 5OLI, 5QL of solenoid drive circuit 4
A solenoid pulp (not shown) is connected between 2 and 2, and as the duty ratio of the current flowing through the solenoid pulp increases, the opening degree of the pulp increases.
A structure that acts to increase oil flow rate is used. Also, when no current is supplied there, the oil supply to the power steering device is reduced.

The operation of the circuit configured in this way is as follows. When the automobile runs, a pulsed vehicle speed signal generated by the vehicle speed sensor 1 is converted into a DC voltage by the 'α voltage conversion circuit. This DC voltage is amplified by an amplifier circuit 3 and supplied to a solenoid drive circuit 4.

At this time, the magnitude of the DC voltage obtained from the voltage conversion circuit 2 becomes smaller as the vehicle speed increases, and the solenoid drive circuit 4 generates a pulse signal whose duty ratio becomes smaller as the magnitude of the input signal becomes smaller. Therefore, the Lunoid drive circuit 4 sends out a pulse signal with a smaller duty ratio as the vehicle speed increases. For this reason, the oil flow rate supplied to the power steering device via the solenoid pulp is controlled to be large at low speeds and small at high speeds, allowing stable steering from low speeds to high speeds.

Next, in 1. Characteristics of the Invention, the operation of a certain disconnection detection circuit 6 will be explained.

It represents the state of being. In this case, the output voltage of the voltage conversion circuit 2 changes as shown in FIG. 2(b).

Then, the disconnection detection circuit 6 sets the voltage at the inverting input terminal of the comparator 6h to a value larger than the voltage at the non-inverting input terminal, and the charging/discharging time constant is also larger on the inverting input terminal side. If constants are set, the voltage at the non-inverting input terminal will change as shown in Figure 2 (C), as shown in Figure 2 (C), and the voltage at the inverting input terminal will change, as shown in ``L''. . Therefore, the voltage "A" at the non-inverting input terminal never exceeds the voltage "K" at the inverting input terminal, and the output signal of the comparator 6h maintains the "0" level both when running and when stopped. .

On the other hand, if the vehicle speed sensor 1 is disconnected at time tl shown in FIG. 3(a), it will no longer send out the vehicle speed signal, so the output voltage of the voltage conversion circuit 2 will rise much more rapidly than in the changing state that occurs during normal driving. L, changes as shown in (a).

At this time, the voltage at the non-inverting input terminal of the comparator 6h immediately follows, as shown by "A" in FIG. 3(b).
The voltage at the inverting input terminal has a large time constant, so it rises slowly as shown at the "mouth". For this reason, the comparator 6)1 detects that the voltage "I" at the non-inverting input terminal becomes odd at time t2.
Since the voltage exceeds the voltage at the inverting input terminal, at this point an output signal of level ``1'' is sent out. This signal is supplied to the control circuit 8 and turns on the transistor 8t, so the relay 8j operates and the contact 8k of the relay 8j switches. Therefore, the power supplied to the solenoid drive circuit 4 is cut off, and a low source pressure is supplied to the transistor 8t via the resistor 8c, and this state is held.

Since the power to the solenoid drive circuit 4 is cut off, it no longer generates a pulse signal, which causes the terminals 5OLI, 5
QL2 A pulse signal is no longer supplied to the solenoid pulp (not shown) connected to K.

Therefore, when a disconnection failure occurs in the vehicle speed sensor 1, the oil supplied from the solenoid pulp to the power steering device decreases, so the required steering force changes in the direction of increasing.
Even if this failure occurs during high-speed driving, safety is maintained.

The above is a description of the features of the present invention. Next, the operation of the short circuit detection circuit 5 will be described.

When the vehicle is running, the vehicle speed sensor 1 generates a vehicle speed signal in which the "l" level and the rOJ level repeatedly occur, as shown in FIG. and - short circuit detection circuit 5
The capacitor 5f is charged through the resistor 5a when the vehicle speed signal is at the "1" level, and discharged through the diode 5d when the vehicle speed signal is at the "O" level. Therefore, the charging time constant is large and the discharging time constant is small, so the capacitor 5
The voltage at the terminal f will never reach the "1" level (the voltage at the non-inverting input terminal of the comparator 5h will be smaller than the "1" level voltage ■1, as shown in "A" in Figure 5). At this time, if the voltage at the inverting input terminal of the comparator 5h is set to a value lower than the "1" level voltage v1 (as shown in "A") (and larger than the maximum voltage of "A"), Since the voltage "A" at the inverting input terminal of the comparator 5h is always higher than the voltage "A" at the non-inverting input terminal, the output of the comparator 5h is always at the rOJ level.

On the other hand, if a short-circuit failure occurs inside the vehicle speed sensor 1 and a continuous signal at the "1" level is sent out from there, the voltage supplied to the non-inverting input terminal of the comparator 5h will change as shown in FIG. The voltage rises from the time t1 at which the failure occurs until it reaches the voltage v1 at the "1" level, as shown in FIG. Therefore, since the voltage "A" at the non-inverting input terminal exceeds the voltage "K" at the inverting input terminal at time t2, the comparator 5h sends out an output signal of the [J level after time t2.

This signal is supplied to the control circuit 7 and is processed by the transistor 7c.
Since it turns on, the base of the transistor 4V of the solenoid and drive circuit 4 must be grounded. Therefore, the transistors 4u and 4v are turned off, and pulse signals are no longer supplied to the solenoid pulp (not shown) connected to the terminals 5OLI and 5OL2. Therefore, when a short circuit failure occurs in the vehicle speed sensor 1, the solenoid pulp Since the amount of oil supplied to the power steering system decreases, the required steering force increases, and even if this failure occurs during high-speed driving, safety is maintained.

The above description applies to a case where a short circuit occurs inside the vehicle speed sensor 1, but the same operation occurs when a short circuit occurs between the output signal line of the vehicle speed sensor 1 and the power supply.

In addition, although the above embodiments were designed to reduce oil flow for safe driving, it is also possible to set this value to an intermediate flow rate. No force is needed.

〔Effect of the invention〕

As explained above, the present invention controls the oil flow rate to a value that allows safe driving when it is detected that the change state of the vehicle speed signal is more rapid than the change state that occurs during normal driving. Therefore, even if the number of devices connected to the vehicle speed sensor changes, the detection x degree will not change, and there is no need to set the detection sensitivity according to the number of devices connected to the vehicle speed sensor, improving work efficiency during installation. It has a good effect.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIGS. 2 and 3 are waveform diagrams of various parts for explaining the operation of the disconnection detection circuit of the vehicle speed sensor in FIG. 1, and FIG. 4 is a vehicle speed signal 5 and 6 are waveform diagrams of various parts for explaining the operation of the short circuit detection circuit of the 11L speed sensor. 1... Vehicle speed sensor, 4... Renoid drive circuit, 5... Short circuit detection circuit, 6... Disconnection detection circuit,
7, 8...Control circuit, 5a-5C26a-6d...
...Resistance, 5d, 6g...Diode, 5f, 6
e, 6f...condens? , 5h, 6h... comparator. Patent Applicant Jidosha Kiki Co., Ltd. Agent Yomasa Oyama) Tatsuj (and 2 others) Fig. 2 I Fig. 4 Fig. 6 Fig. 3 Fig. 5

Claims (1)

[Claims] In a power steering device control device that generates a vehicle speed signal corresponding to vehicle speed and controls oil flow based on this vehicle speed signal, the state of change in the vehicle speed signal is more rapid than the state of change that occurs during normal driving. A control device for a power steering device, comprising: a detection circuit that generates an output signal when detecting the .