JP2881253B2 - Power steering device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electric power steering apparatus (power steering) that assists a force required for steering operation.

(Prior art)

Detecting a steering torque applied to the steering wheel, and when the detected torque exceeds a predetermined dead zone, drives a motor for steering assistance by flowing a drive current determined according to the detected torque, 2. Description of the Related Art There has been developed an electric power steering apparatus that assists a force required for steering of an automobile by a rotational force of the motor and provides a driver with a comfortable steering feeling.

FIG. 4 is a block diagram showing the overall configuration of a conventional power steering device. Such a power steering device has a motor driving circuit 21 for driving the motor 1, an electromagnetic clutch driving circuit 22 for driving the electromagnetic clutch 2, and a fail-safe relay 23 when an appropriate mounting space is not secured in mounting to the vehicle body. And a control circuit 11 that supplies a logic signal for control to the power unit 20 in accordance with input signals from a detector such as a torque sensor 3 for detecting a steering torque and a vehicle speed sensor 4 for detecting a vehicle speed. And a control unit 10 composed of The power unit 20 and the control unit 10 are connected by a transmission line L,
Via the transmission line L, the control unit 10 sends the power unit 20 an ON signal which is a signal for driving devices such as the motor 1, the electromagnetic clutch 2 and the fail-safe relay 23, and an OFF signal which is a signal for the non-drive side. Each drive circuit of the power unit 20 operates by sending two types of logical control signals.

[Problems to be solved by the invention]

However, in the power steering apparatus in which the power unit 20 and the control unit 10 are separately disposed as described above, when a disconnection, ground fault, or cross-contact occurs in the transmission line L, the corresponding drive circuit of the power unit 20 malfunctions. Causing a dangerous situation in some cases. For example, the motor drive circuit 21 drives the motor 1 when the logical control signal is at a low level.
If the logical control signal is fixed at a low level due to the grounding of the transmission line L to 21, an unexpected steering assist force acts on the steering mechanism, which is dangerous.

The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a power steering device with high safety by suppressing a malfunction of a power unit when a disconnection, ground fault, or cross-contact occurs in a transmission line. Aim.

[Means for solving the problem]

The power steering device according to the present invention is divided into a first unit for driving a steering assist device and a second unit for controlling the first unit, and transmits a signal output from the second unit. A power steering device for controlling the first unit by giving it to the first unit via a line, a conversion unit provided in the second unit, for converting a logical control signal into a pulse signal of a predetermined frequency and outputting the pulse signal; Determining means provided in the first unit for determining whether the frequency of the pulse signal input from the conversion means is within a predetermined range; and determining that the frequency of the pulse signal is within a predetermined range by the determining means. And means for converting the pulse signal into the logical control signal only when it is determined that the logical control signal is present.

[Action]

When a failure occurs between the control unit (the second unit) and the power unit (the first unit) such as disconnection, ground fault, and contact in the transmission line, an erroneous signal similar to the logical control signal may be generated. However, in the power unit (first unit), the control unit (second unit)
Only when the frequency of the pulse signal given from the unit is within a predetermined range, the pulse signal indicating the ON logical control signal is made valid, and this pulse signal is converted into the ON logical control signal. Therefore, the erroneous signal is not processed as an ON logical control signal.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments. FIG. 1 is a block diagram showing the overall configuration of a power steering device according to the present invention.

In the figure, reference numeral 10 denotes a control unit 10 including a control circuit 11, a reference pulse generator 12, a frequency divider 13, and pulse conversion circuits 14, 15, and 16. In the control unit 10, the control circuit 11 includes a microprocessor, and drives devices such as the motor 1 and the electromagnetic clutch 2 based on various detection signals provided from sensors such as the torque sensor 3 and the vehicle speed sensor 4, and performs a failure. Control signals for performing the safe operation are supplied to the pulse conversion circuits 14, 15, and 16. Further, the reference pulse generator 12 generates a reference pulse signal of a predetermined frequency and supplies the reference pulse signal to the frequency divider 13. The frequency divider 13 divides the reference pulse signal into a plurality of different types of frequencies into pulse signals, and provides these pulse signals to the pulse conversion circuits 14, 15, and 16 respectively. The pulse conversion circuits 14, 15, and 16 convert the pulse signal supplied from the frequency divider 13 into the pulse determination circuits 24, 25 via the transmission line L only when an ON control signal is supplied from the control circuit 11. , 26 respectively.

In the figure, reference numeral 20 denotes a motor drive circuit 21, a clutch drive circuit 22, a fail-safe relay 23, and pulse determination circuits 24 and 2.
It is a power unit consisting of 5,26. Power unit 20
In the above, the pulse determination circuit 24 determines whether or not the frequency of the pulse signal provided from the pulse conversion circuit 14 is within a predetermined range. If the frequency of the pulse signal is within the predetermined range, the motor drive for driving the motor 1 is performed. The circuit 21 is supplied with an ON logical control signal. Similarly, the pulse determination circuit 25 determines whether or not the frequency of the pulse signal provided from the pulse exchange circuit 15 is within a predetermined range. If the frequency of the pulse signal is within the predetermined range, the electromagnetic clutch 2 of the motor 1 A pulse determination circuit 26 determines whether or not the frequency of the pulse signal supplied from the pulse conversion circuit 16 is within a predetermined range. If the frequency is in the predetermined range,
An ON logical control signal is given to a fail-safe relay 23 that performs a relay operation for performing a fail-safe operation for interlocking a predetermined control system.

The motor drive circuit 21 drives the motor 1 based on the ON logical control signal supplied from the pulse determination circuit 24, and the clutch drive circuit 22 controls the ON logical control supplied from the pulse determination circuit 25. The electromagnetic clutch 2 is driven based on the signal. Also, Feinol Safe Relay 23
Causes the fail-safe operation to be executed based on the OFF logical control signal given from the pulse determination circuit 26.

Fig. 2 shows the power unit from the control unit 10.
It is a detailed block diagram of a transmission circuit of control signals up to 20,
As an example, a transmission circuit of a control signal from the reference pulse generator 12 to the pulse determination circuit 25 is shown. This transmission circuit will be described. Note that the clutch drive circuit 22 is a pulse determination circuit.
When the logical control signal supplied from 25 is at a high level, the electromagnetic clutch 2 is engaged.

In the control unit 10, the reference pulse generator
A reference pulse signal of a predetermined frequency is provided from 12 to the frequency divider 13. The frequency divider 13 divides the frequency of the reference pulse signal, and supplies pulse signals of a plurality of different predetermined frequencies to the pulse conversion circuits 14, 15, and 16.

In the pulse conversion circuit 15, the pulse signal a provided from the frequency divider 13 is input to one input terminal of the NAND circuit 151. N
The logical control signal b from the control circuit 11 is input to the other input terminal of the AND circuit 151. The output of the NAND circuit 151 is sent to the transmission line L via the diode clamp circuit 152, the resistor 153 and the output terminal P0 of the control unit 10, and is applied to the input terminal P1 of the power unit 20 via the transmission line L. The logical control signal given to the power unit 20 is the resistance 2501 of the pulse determination circuit 25, the diode clamp circuit 250
The signal is supplied to the first inverter 2503 through the second inverter 2, and the signal is inverted by the first inverter 2503. The output signal d of the first inverter 2503 is applied to the trigger input terminal B ₂ of the trigger input terminal ₁ and the second circuit 252 of the first circuit 251 in the semiconductor integrated circuit 250 formed by a monostable multivibrator 2 circuit built.

The first circuit 251 (or the second circuit 252) includes two trigger input terminals, a trigger input terminal ₁ ( ₂ ) and a trigger input terminal B ₁ (B ₂ ), respectively, and the trigger input terminal ₁ ( ₂ ).
When the output signal d applied to the input terminal changes from high level to low level or when the signal d applied to the trigger input terminal B ₁ (B ₂ ) changes from low level to high level, the output terminal Q ₁ (Q ₂ ) Outputs a positive one-shot pulse from the output terminal ₁ ( ₂ ) and a negative one-shot pulse from the output terminal ₁ ( ₂ ). The pulse width of the one-shot pulse output from the output terminal Q ₁ (Q ₂ ) and the output terminal ₁ ( ₂ ) is determined by the timing terminal Rx ₁ / Cx ₁ (Rx ₂ / Cx ₂ )
And a resistor 2511 externally connected to the timing terminal Cx ₁ (CX ₂ )
(The resistor 2521) and the capacitor 2512 (the capacitor 2512). When the output signal d has a predetermined frequency, the width of the one-shot pulse is such that the one-shot pulse of the output signal e and the pulse of the output signal d overlap by a predetermined width, and the output terminal Q ₂
Output signal is a high level continuous value, while output terminal ₂
Are adjusted so as to be continuous values of low level.

Trigger input terminal B ₁ of the first circuit 251 is always fixed at the high level, the output signal e outputted from the output terminal Q ₁
Is supplied to the trigger input terminal ₂ of the second circuit 252. Signal output from the output terminal Q ₂ of the second circuit 252 charging resistor 2
Via 504, one end is provided to a grounded capacitor 2505. On the other hand, the signal output from the output terminal ₂ is
The collector is connected to the other end of the capacitor 2505 via the discharge resistor 2507 and the emitter is provided to the switching transistor 2506 whose ground is grounded. The output of the capacitor 2505 is provided to a second inverter 2508 and inverted. Further, the output of the second inverter 2508 is applied to the third inverter 2509 and inverted, and the output signal g of the third inverter 2509 is applied to the clutch drive circuit 22.

3 (a) to 3 (g) are waveform diagrams showing signals at various parts in FIG. 2, and FIG. 3 (a) shows the output signal a of the frequency divider 13 and the third signal.
FIG. 4B shows a logical control signal which is an output signal of the control circuit 11.
b, FIG. 3 (c) is the output signal c of the pulse conversion circuit 15, FIG. 3 (d) is the output signal d of the first inverter 2503, FIG. 3 (e)
The output signal e, the third diagram of the output terminal to Q ₁ first circuit 251 (f)
3 (g) shows the waveform of the output signal f of the capacitor 2505, and FIG. 3 (g) shows the waveform of the output signal g of the third inverter 2509.

In FIG. 3, time t _{1 to} t ₄ is a state in which an ON logical control signal is output from the control circuit 11, and in this state, time t _{1 to} t ₂ is a state in which the transmission line L has no contact. husband a state in which frequency is lower in time t ₂ ~t ₃ is a state in which the frequency is higher in output signal d by mixed contact of the transmission line L, the time t ₃ ~t ₄ output signal d by incompatible transmission Hsuan L s Is shown.

First described the absence mixed contact the transmission line L at time t ₁ ~t _2.

The output signal c of the pulse conversion circuit 15 is such that the logical control signal b input to the NAND circuit 151 is at a high level and the pulse signal a
Is at a low level when is at a high level, and at a high level otherwise. Accordingly, when the logical control signal a becomes high level and the pulse signal b is input to the NAND circuit 151, the output signal c becomes a pulse signal having the opposite polarity to the pulse signal a. The first inverter 2503 outputs a pulse signal in which the polarity of the output signal c is inverted as the output signal d.

In the first circuit 251 of the pulse determination circuit 25, when the output signal d having the frequency determined by the frequency divider 13 is input to the trigger input terminal ₁ , the pulse of the output signal d changes from the high level to the low level. Occasionally, give from the output terminal Q ₁ shot pulse having a predetermined width to the trigger input terminal ₂ of the second circuit 252 as an output signal e. In this case, the output signal e
Has a waveform in which the one-shot pulses are arranged at predetermined intervals. The output interval of the one-shot pulse changes according to the frequency of the output signal d.

In the second circuit 252, when the output signal e input to the trigger input terminal ₂ changes from high level to low level,
Trigger input terminal B ₂ to the inputted output signal d one-shot pulse from a low level from the output terminal Q ₂ in the time of change to the high level positive of negative polarity one-shot pulse from the output terminal ₂ is outputted . The width of the one-shot pulse is equal to the output signal e when the output signal d has a predetermined frequency.
Output signals of the output terminal Q ₂ and the one-shot pulse by the one-shot pulse and the output signal d is overlap by a predetermined width by the successive values of a high level, while the output signal of the output terminal ₂ becomes the successive values of the low level. Therefore, the capacitor 2505 charges as indicated by the output signal f. When the output voltage f, which is the amount of charge, becomes equal to or higher than the threshold value Vs of the second inverter 2508, the output signal of the second inverter 2508 becomes low level, and the output signal g of the third inverter 2509 becomes high level. This high-level signal is supplied to the clutch drive circuit 12, and the electromagnetic clutch 2 is driven.

Then incompatible occurs in transmission line L, when the frequency of the output signal d is higher for (time t ₂ ~t ₃₎ will be described.

In this case, due to the high frequency of the output signal d is inputted to the trigger input terminal _1, an output signal e output supplied from the terminal Q ₁ to the trigger input terminal ₂ of the second circuit 252 of the first circuit 251, one shot The pulses overlap to form a high level continuous value. The circuit characteristics of the second circuit 252, when an input signal of the trigger input terminal ₂ is at a high level of continuous values, successive values of the output signal from the output terminal Q ₂ is at a low level, while the output signal of the output terminal ₂ is high The level becomes a continuous value, and the switching transistor 2506 is turned on. As a result, the charge of the capacitor 2505 is discharged, so that the output voltage f becomes 0, and the output signal g of the third inverter 2509 becomes
Becomes a low level continuous value and the clutch drive circuit does not operate.

Then incompatible occurs in transmission line L, the frequency of the output signal d will be described when it becomes low (time t ₃ ~t _4).

In this case, due to the low frequency of the output signal d is inputted to the trigger input terminal _1, an output signal e output supplied from the terminal Q ₁ to the trigger input terminal ₂ of the second circuit 252 of the first circuit 251, one shot The interval between pulses is wide. Also,
Since the frequency is given a low output signal d to the trigger input terminal B _2, regularly before on the switching transistor 2506 is short time interval, repeatedly off, the electric charge of the capacitor 2505 reaches a threshold value Vs of the second inverter 2508 The maximum value of the output voltage f is the second inverter
It becomes a sawtooth-shaped waveform that is smaller than the threshold value Vs of 2508,
The output signal g of the third inverter 2509 becomes a low level continuous value, and the clutch drive circuit 22 does not operate.

Thus, in the present invention, the control unit
The ON logical control signal is supplied to the power unit 20 as a pulse signal of a predetermined frequency from the power unit 20.
In the pulse determination circuits 24, 25, and 26, the ON logical control signal is supplied to each drive circuit only when the frequency of the pulse signal given from the control unit 10 is within a predetermined range. Has become. For this reason, when a touch occurs in the transmission line L, an ON logical control signal is not supplied to each drive circuit of the power unit 20, and malfunction of the power unit 20 can be suppressed.

In this embodiment, three pulse conversion circuits and three pulse determination circuits are provided, and the motor drive circuit 21
The logical control signal is given to the clutch drive circuit 22 and the fail-safe relay 23. However, the present invention is not limited to this. More than three pulse conversion circuits and three pulse determination circuits are provided, and the logical control signal is supplied to the drive circuits of other devices. Needless to say, it may be given.

〔effect〕

As described above in detail, in the power steering apparatus according to the present invention, the power unit (first unit) is controlled only when the frequency of the pulse signal given from the control unit (second unit) is within a predetermined range. The pulse signal is determined to indicate an ON logical control signal, and the pulse signal is converted into an ON logical control signal. The power unit (first unit) and the control unit (second unit) Since the erroneous signal generated when disconnection, ground fault, and cross-contact occur in the transmission line between them becomes invalid, the present invention has excellent effects such as preventing malfunction of the power unit (first unit) and improving safety. Play.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of a power steering apparatus according to the present invention, FIG. 2 is a detailed block diagram of a control signal transmission circuit from a reference pulse generator to a pulse determination circuit, and FIG.
FIG. 2 is a waveform diagram showing signals of respective parts in FIG. 2, and FIG. 4 is a block diagram showing an overall configuration of a conventional power steering device. 1 ... motor, 2 ... electromagnetic clutch, 10 ... control unit, 14,15,16 ... pulse conversion circuit, 20 ... power unit, 24,25,26 ... pulse judgment circuit

Claims (1)

(57) [Claims] 1. A first unit for driving a steering assist device and a second unit for controlling the first unit, and a signal output from the second unit is transmitted to a second unit via a transmission line. A power steering device that controls the first unit by providing the first unit with the first unit; a conversion unit that is provided in the second unit and converts a logical control signal into a pulse signal of a predetermined frequency and outputs the pulse signal; Determining means for determining whether the frequency of the pulse signal input from the converting means is within a predetermined range; and determining that the frequency of the pulse signal is within a predetermined range by the determining means. Means for converting the pulse signal into the logical control signal only in the case where the power steering device is used.