JP2006315620A - In-vehicle electronic control device relay drive circuit - Google Patents

Abstract

A system for monitoring a microcomputer in a vehicle-mounted electronic control device by communication with a peripheral IC, and when a communication abnormality occurs during serial communication, the abnormality can be detected and a fail-safe relay can be shut off quickly and reliably. A relay drive circuit for an in-vehicle electronic control device is obtained.
In an in-vehicle electronic control device 10 provided with a microcomputer 30 and a peripheral IC 20, serial communication of data is performed by a serial communication buffer 22 of the peripheral IC 20 and a serial communication unit 34 of the microcomputer 30. Is detected by the microcomputer 30 and a special WD pulse signal is generated and sent to the WD monitoring unit 24 of the peripheral IC 20, and when the signal is received, a signal is sent to the relay drive unit 21 and the solenoid The relay 42 is configured to shut off the relay 42, and the relay drive circuit is configured to operate the fail-safe relay quickly and reliably.
[Selection] Figure 1

Description

  The present invention relates to a relay drive circuit of an in-vehicle electronic control device that controls a brake device of a vehicle.

  An on-vehicle electronic control unit (ECU) that controls a vehicle brake device includes a microcomputer-based electronic control circuit that outputs a control signal based on signals from various sensors such as a vehicle running state and a hydraulic pressure of a hydraulic circuit; It consists of various sensors and monitoring circuits on the input side, and peripheral ICs that integrate the electrical and electronic components of electrical functional members such as solenoid valves, hydraulic pumps, and relays on the output side into an IC. As an example having such an ECU, Patent Document 1 discloses a “microcomputer monitoring method in an electronic control device”. The purpose of the monitoring method according to this publication is to perform data communication from a microcomputer to a peripheral IC without using two microcomputers, and to monitor abnormality of the microcomputer based on this data communication.

  The ECU used in the microcomputer monitoring method is for a system that performs ABS control (anti-lock control) in the hydraulic circuit of the brake device, and is a solenoid drive driver that turns on and off the microcomputer of the electronic control circuit and the solenoid of the solenoid valve. , Peripheral wheels such as an input side wheel speed signal, an input buffer for receiving a switch signal, a serial communication buffer, an internal oscillation circuit (clock), a WD (watchdog) monitoring unit, a relay driving unit, and a power output circuit. In this ECU, the microcomputer and the peripheral IC are monitored by communication from the microcomputer to the peripheral IC, but for a fail-safe solenoid provided in a power supply line that supplies power to a plurality of solenoid circuits. The relay is turned on and off by a dedicated signal line connecting the output section of the microcomputer to the relay drive section provided in the peripheral IC.

However, in the above-described method for controlling on / off of the relay, a communication error occurs in any of a series of control signal systems such as a solenoid and an instruction to the power circuit of the pump motor from the input signals of various sensors. If the error is detected, the signal sent from the serial communication part of the microcomputer to the serial communication buffer of the peripheral IC is monitored by the serial signal monitoring part, and the abnormality is detected by the microcomputer. Thus, the relay signal is stopped via the dedicated signal line of the relay driving unit, and the relay is cut off. For this reason, even if the above abnormality occurs, the relay cannot be immediately cut off, and the relay cut-off may be delayed.
Japanese Patent Laid-Open No. 2001-312315

  The present invention is a system for monitoring the microcomputer in the in-vehicle electronic control device by communication with the peripheral IC in consideration of the above-mentioned problem. Even when a signal abnormality occurs during serial communication, the abnormality is detected quickly and quickly. It is an object of the present invention to provide a relay drive circuit for an on-vehicle electronic control device that can reliably cut off a fail-safe relay.

  The present invention includes, as means for solving the above problems, a microcomputer 30 for controlling a vehicle brake device and a peripheral IC 20 for processing, monitoring, blocking and / or prohibiting a signal on the input side thereof. Performs serial communication of data from the microcomputer, and if a communication abnormality occurs during the communication, a special WD abnormality pulse signal is output from the microcomputer 30 and the solenoid relay 42 of the fail-safe relay is shut off based on the detection signal. The relay drive circuit of the on-vehicle electronic control device configured as described above is used.

  According to the relay drive circuit of the on-vehicle electronic control device of the present invention having the above-described configuration, the detection signals from various sensors representing the running state of the vehicle, such as the wheel speed sensor and the pressure sensor of the hydraulic circuit, are output from the microcomputer having the arithmetic circuit. When input to the input unit, the microcomputer performs calculations necessary for controlling the brake device based on these signals and calculates various control signals in the calculation unit. A signal for controlling the operation of the load is sent out, and the data sent to the serial communication buffer of the peripheral IC, the WD (watchdog) monitoring unit or the like is monitored to determine whether these calculations and controls are normally performed. .

  When monitoring such a microcomputer with a peripheral IC, in a normal state, a data signal is sent from the serial communication unit of the microcomputer to the serial communication buffer of the peripheral IC in order to monitor the operation data, and the data is monitored. In order to activate the fail-safe relay of the relay drive circuit, a relay drive signal is transmitted via the serial communication line, and when the relay drive signal is received by the peripheral IC, the fail-safe relay is turned on via the relay drive unit. To do. Therefore, in this configuration, the relay dedicated signal line from the microcomputer to the relay drive unit is omitted.

  When a communication abnormality occurs in serial communication with the fail-safe relay turned on by the relay drive circuit, a signal from the communication is sent back from the peripheral IC to the microcomputer, and the microcomputer detects the communication abnormality. When the microcomputer detects this communication abnormality, a special WD abnormality pulse signal prepared in advance is intentionally sent from the microcomputer to the WD monitoring unit of the peripheral IC. When the WD monitoring unit receives this special WD abnormal pulse signal, the WD monitoring unit directly sends a cut-off signal (OFF) to the relay drive unit, and based on this signal, the fail-safe relay is turned off and cut off. For this reason, it is possible to operate the fail-safe relay quickly and reliably without using the relay dedicated signal line.

  The relay drive circuit of the on-vehicle electronic control device according to the present invention intentionally sends a WD abnormal pulse signal to the peripheral IC when the microcomputer detects a communication error between the serial communication buffers of the peripheral IC that monitors the operation of the microcomputer. Since the relay is directly cut off by the relay drive circuit, it is possible to quickly and surely cut off the relay by detecting the communication abnormality of the microcomputer, and to improve the reliability of the fail safe relay. This eliminates the relay dedicated signal line between the microcomputer and the peripheral IC, thereby simplifying the circuit complexity and reducing the cost.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram of an on-vehicle electronic control device (hereinafter abbreviated as ECU) 10 including a relay drive circuit of an embodiment. The illustrated ECU 10 will be described for a case where the ECU 10 is applied to an example of a brake device that performs ABS control to be described later. As shown in the figure, the ECU 10 includes an input side peripheral IC 20, an electronic control circuit including a microcomputer 30, a solenoid relay 42 (a pump motor relay is omitted), a drive driver 40 a that drives solenoids 41 a, 41 b. , 40b, etc., and the output side peripheral IC 40 is included.

The peripheral IC 20 on the input side includes a relay drive unit 21 that drives a relay of a solenoid power line, a serial communication buffer 22, a CPU monitoring unit 23, a WD monitoring unit 24, a reset control unit 25, a power supply monitoring unit 26, and an internal clock monitoring unit. 27, etc., and further, a signal processing unit for processing a waveform representing signals representing the traveling state of the vehicle from various sensors such as wheel speed sensors S ₁ and S ₂ and a pedaling force sensor P _H (see FIG. 2), etc. 1 is not shown). In the figure, a solid line indicates a control system line, a broken line indicates a monitoring system line, and an alternate long and short dash line indicates a prohibited or shut-off line. However, lines that are not necessary for this embodiment are omitted.

In the peripheral IC 20, on / off information data of the solenoid relay 42 sent from the microcomputer 30 via the serial communication line l _S is received by the serial communication buffer 22, and the received information is monitored by the CPU monitoring unit 23. At the same time, the output of the serial communication buffer 22 is sent to the relay drive unit 21, and on / off of the solenoid relay 42 is controlled by a command from the relay drive unit 21. A WD (watchdog) monitoring unit 24 monitors whether the calculation is appropriate based on a WD pulse signal based on calculation cycle data sent from the microcomputer. When a communication abnormality occurs during serial communication, the WD monitoring unit 24 is configured to transmit a special WD abnormality pulse output described later from the WD output terminal of the microcomputer 30.

  The reset control unit 25 is configured to send a reset signal to the reset terminal RST of the microcomputer 30 when a reset signal is input from the WD monitoring unit 24 and / or the power supply monitoring unit 26. The internal clock monitoring unit 27 forms an internal clock signal used by the serial communication buffer 22 and the power supply monitoring unit 26, and performs monitoring by selecting and using a clock signal having a timing suitable for each. In addition to the above, the peripheral IC 20 is provided with a power output circuit, an overheat protection circuit, a temperature monitoring unit, and the like, which are omitted for simplification of illustration.

  Next, the microcomputer 30 includes an input unit 31, a calculation unit (CPU) 32, and an output unit 33. When signals from various sensors such as the wheel speed sensor described above are input to the input unit 31, the various information Based on the ABS control program, and based on the calculation result, the output unit 33 sends a control signal necessary for the ABS control to the solenoid drive drivers 40a, 40b... In the peripheral IC 40 on the output side. , And is configured to perform ABS control. Further, the microcomputer 30 is provided with a serial communication unit 34, which serializes various data signals such as ABS control signals obtained by the calculation by the calculation unit 32 and sends them to the serial communication buffer 22 of the peripheral IC 20 on the input side. I am doing so.

  Further, the microcomputer 30 sends out a WD pulse signal from the WD terminal, and sends out as a WD pulse signal whether various calculations based on the input signal in the calculation unit 32 are properly performed. This WD pulse signal is output, for example, as a periodic signal in which 0 and 1 are alternately inverted if the calculation is properly performed. If the calculation is not correct, the WD pulse signal is reset by the output from the WD monitoring unit 24 of the peripheral IC 20 described above. A reset signal is sent from the control unit 25 to the reset terminal of the microcomputer 30 to set each value in the calculation in the microcomputer to the reset (0) state.

  Further, when an abnormality occurs in the serial communication via the serial communication line, the microcomputer 30 detects an abnormality in the serial communication buffer 22 of the peripheral IC 20 and receives the abnormality detection from the input unit 31 of the microcomputer 30 for communication. When an abnormality is detected, the calculation unit (CPU) 32 intentionally outputs a special WD abnormal pulse signal programmed in advance. The special WD abnormal pulse signal is not a signal sequence that periodically repeats 0 and 1, but is a special signal sequence such as a Hi signal sequence in which 1-byte signals are all 1s.

  This is because even if the calculation by the calculation unit 32 is normal, monitoring becomes impossible if an abnormality occurs in the monitoring line by serial communication. In such a case, if a special signal is not intentionally output, This is because it takes time until the relay is cut off due to an abnormality, and the operation of the fail-safe relay is delayed. The operation when such a WD abnormal pulse signal is sent to the WD monitoring unit 24 of the peripheral IC 20 will be described later.

  The peripheral IC 40 on the output side is provided with drive drivers 40a, 40b... For solenoids 41a, 41b. The drive drivers 40a, 40b,... Use semiconductor switching elements such as MOSFET transistors and are not shown, but control signals to the drive drivers 40a, 40b,. And an output signal from an AND circuit that receives an output signal from the output circuit and a signal from an output monitoring unit that monitors the energization state of each drive driver.

According to the above-described on-vehicle electronic control unit (ECU), the relay drive circuit that drives the solenoid relay 42 can perform the relay cutoff very quickly and surely at the time of communication abnormality. When the ignition switch SW of the vehicle is turned on and the ECU 10 is activated and the control by the ECU 10 is started, the ECU 10 connects the peripheral IC 20 on the input side that monitors the microcomputer 30 to the microcomputer 30 via the serial communication line l _S. The data of the calculation result by the calculation unit 32 is transmitted by serial communication and monitored by the serial communication buffer 22 and the CPU monitoring unit 23. As long as reception by the serial communication buffer 22 is normal, the solenoid relay 42 is turned on by the output from the serial communication buffer 22, and power is supplied to the solenoids 41a, 41b,.

  However, when a communication abnormality in the serial communication is detected by the CPU monitoring unit 23, the microcomputer 30 also detects the communication abnormality, a special WD abnormality pulse signal is generated based on the detection result, and the peripheral IC 20 It is intentionally sent from the microcomputer 30 to the WD monitoring unit 24. When the WD abnormal pulse signal is received by the WD monitoring unit 24, a signal for relay disconnection is directly sent from the WD monitoring unit 24 to the relay driving unit 21, thereby turning off the solenoid relay 42. As a result, even when a communication abnormality occurs, the fail-safe relay can be operated by quickly and reliably cutting off the relay.

  When the calculation cycle or the like in the calculation unit 32 of the microcomputer 30 is not appropriate as described above, the WD monitoring unit 24 receives a normal WD pulse signal error and relays the relay cutoff signal. It goes without saying that the relay can be cut off as in the case of communication abnormality. By adopting such a relay drive circuit, it becomes unnecessary to provide a signal line dedicated to the relay and the terminal for connecting the output terminal connected to the output section 33 of the microcomputer 30 and the relay drive section 21. In addition, the operation of the fail-safe relay becomes faster and the reliability is improved.

An example of the hydraulic brake device A to which the on-vehicle electronic control unit (ECU) 10 including the relay drive circuit of the above embodiment is applied is shown in FIG. The hydraulic brake device A shown in the figure is a device having a function of performing ABS control, and is a conventionally known device. Therefore, the schematic configuration thereof will be briefly described below. For simplification, the wheel cylinder 4 and its hydraulic circuit are shown only for one of the two wheels (FL, RR) of the two systems using the X piping in FIG. As shown, another piping system with similar members is provided. Further, the piping is not limited to the two pipings by the X piping shown in FIG. The wheel (FL, RR) is provided with a wheel cylinder 4, and a brake fluid pressure corresponding to the operating force of the brake pedal 1 is generated by the master cylinder 2, and a two-position control valve 3a (in the figure, 3a _F , 3a _R and The hydraulic pressure is supplied to the wheel cylinders 4 via 3a (represented by 3a in which the subscripts _F and _R are omitted).

A bypass pipe including a check valve 5 is connected between the upstream and downstream of the two-position control valve 3a, and the wheel cylinder 4 is indicated by a two-position control valve 3b (3b _F and 3b _{R in the} figure). A low pressure reservoir 6 for storing the hydraulic fluid discharged from the wheel cylinder is connected via the subscripts _F and _R (represented by 3b in which the subscripts _F and _R are omitted). And a check valve 8 is connected, and its piping draws hydraulic fluid from the reservoir 6 and is connected to a hydraulic circuit between the master cylinder 2 and the two-position control valve 3a.

The two-position control valves 3a (pressurization electromagnetic switching valves) and 3b (pressure-reducing electromagnetic switching valves) are normally-open and normally-closed two-position control valves driven by a solenoid having a communication position and a shut-off position. The communication position and the blocking position can be switched by energizing 41b. In the illustrated example, the two-position control valve 3a is used by being set to a position where the hydraulic pressure is communicated by turning off the energization of the solenoid 41a. Rotation of the wheels (FL, RR) detection signal from the wheel speed sensors S _1, S _2, also the state of depression of the brake pedal 1 is detected sends a detection signal from the depression force sensor P _H to the peripheral IC20 of ECU10 described above The

The wheel speed sensors S _1, S _2, ECU 10 based on the detection signal from the depression force sensor P _H or the like detects the wheel speed, calculates a vehicle body estimated speed from that value, the ABS control based on the calculation result Various necessary control signals are generated, and the solenoids 41a, 41b,..., The motor of the hydraulic pump 7 and the solenoid relay 42 of the fail-safe relay are driven to perform ABS control. Although the ABS control method itself is a known control, the ABS control operation is performed by an on-vehicle electronic control unit (ECU) 10 including the relay drive circuit of the above-described embodiment.

  Although the relay drive circuit of the on-vehicle electronic control device is applied to the hydraulic brake control device A in FIG. 2, a hydraulic brake control device other than that shown, for example, Japanese Patent Laid-Open No. 2003-205838 The present invention can also be applied to a relay drive circuit of an electronic control device that controls a hydraulic brake control device using another system such as a brake-by-wire system using a hydraulic circuit shown in FIG.

  The relay drive circuit of the on-vehicle electronic control device according to the present invention can quickly and surely cut off the relay when communication between the microcomputer and the peripheral IC is abnormal, and is widely used in various electronic control devices for controlling the hydraulic brake control device. Is done.

Overall appearance block diagram of in-vehicle electronic control device including relay drive circuit of embodiment (A) Schematic system diagram of one system of hydraulic circuit, (b) Schematic diagram of entire piping system

Explanation of symbols

10 On-vehicle electronic control device 20 Peripheral IC
21 relay drive unit 22 serial communication buffer 23 CPU monitoring unit 24 WD monitoring unit 25 reset control unit 26 power supply monitoring unit 27 internal clock monitoring unit 30 microcomputer 31 input unit 32 arithmetic unit 33 output unit 34 serial communication unit 40 peripheral IC
41a, 41b Solenoid 42 Solenoid relay

Claims (3)

  A microcomputer (30) for controlling the brake device of the vehicle, and a peripheral IC (20) for processing, monitoring, and / or prohibiting the signal processing of the input side, relays, etc., the peripheral IC (20) When serial communication of data is performed from the microcomputer and a communication abnormality occurs during the communication, a special WD abnormal pulse signal is output from the microcomputer (30), and the solenoid relay (42) of the fail-safe relay is output based on the detection signal. ) Is a relay drive circuit for an in-vehicle electronic control device.   The peripheral IC (20) is driven by a serial communication buffer (22) for serial communication with the serial communication unit (34) of the microcomputer (30) and a solenoid relay (42) on the power line of the electrical load. A relay drive unit (21) and a WD monitoring unit (24) for monitoring the operation of the microcomputer by a calculation cycle pulse of the microcomputer (30) are provided. When a communication abnormality occurs during serial communication, the microcomputer (30) The communication abnormality is detected by the microcomputer (30), a special WD abnormal pulse signal is generated, the WD abnormal pulse signal is output to the WD monitoring unit (24), and the signal from the WD monitoring unit (24) is output. Directly sent to the relay drive unit (21), and the relay drive unit (21) shuts off the solenoid relay (42). Relay driving circuit of the vehicle electronic control unit according to claim 1, wherein the door.   The relay for an on-vehicle electronic control device according to claim 1 or 2, wherein the solenoid relay (42) is provided on a power supply line for supplying power to a solenoid (41) of a solenoid valve of a brake device. Driving circuit.

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