JPH10278729A - On-vehicle control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a step-up circuit of compact electronic parts, which can be operated by small power, by providing a first step-up circuit for raising the battery voltage to the predetermined value, a second step-up circuit for raising the battery voltage to a value lower than the predetermined value, and a constant voltage circuit for evening the voltage of the step-up circuit at a constant voltage. SOLUTION: A constant voltage circuit 33 is provided in spite of using a switch circuit to be interposed in series to a power source line, and furthermore, a second step-up circuit 34 for outputting the voltage at 9V smaller than the voltage at 21V of a first step-up circuit 3' is connected between an input terminal of the constant voltage circuit 33 and an input line of the first step-up circuit 3'. With this structure, constant voltage is always supplied to a side air bag system 32 of a driver's seat from the second step-up circuit 34 through the constant voltage circuit 33.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-vehicle control device applicable to an occupant protection device provided with an airbag or the like for protecting an occupant in the event of a collision from the front and side of a vehicle.

[0002]

2. Description of the Related Art A vehicle-mounted control device of this type will be described with reference to an occupant protection device shown in FIG. First, the driver's seat airbag system, which is the main occupant protection device (main control means)
23 will be described. That is, reference numeral 3 denotes a booster circuit, which is a battery 1 supplied through an ignition switch 2.
, The backup capacitor 5 is charged through the resistor 4, the first switch circuit 7 inserted in series with the power supply line 6, and the driver seat, which is the auxiliary occupant protection device, is connected through the resistor 8. The boosted voltage is supplied to a side airbag system (sub-control unit) 32. Reference numeral 9 denotes a longitudinal acceleration sensor for detecting acceleration generated in the longitudinal direction of the vehicle. An acceleration signal, which is a detection signal, is supplied to a microcomputer 10 described later.

The microcomputer 10 has a collision judging function, and turns on the second switch circuit 11 when judging a serious collision based on the acceleration signal supplied from the longitudinal acceleration sensor 9 to turn on the backup capacitor. 5 is charged to the discharge diode 1
2, the primer 13, the mechanical acceleration switch 1
Then, an ignition current is applied in series to 4 to deploy the airbag attached to the handle. It is needless to say that the mechanical acceleration switch 14 is turned on at this time.

The microcomputer 10 has a failure diagnosis function for the backup capacitor 5, the primers 13, 18, the mechanical acceleration switch 14, etc. In the capacity diagnosis of the backup capacitor 5, the microcomputer 10 turns on the ignition switch 2. Immediately after, signal line Y
By turning off the first switch circuit 7 through
After the charge of the backup capacitor 5 is prevented from being discharged as dark current to each circuit of the driver side airbag system 32, the switching transistor 1
6 is turned on, the electric charge charged in the backup capacitor 5 is discharged via the resistor 15, and the microcomputer 10 reads a change amount of the terminal voltage of the backup capacitor 5 during a predetermined time at that time. The capacitance is calculated and the capacitance is diagnosed. If the capacitance value is determined to be abnormal, the occupant is notified using an alarm device such as a lamp (not shown).

[0005] The microcomputer 10 determines the disconnection diagnosis of the primers 13 and 18 and the mechanical acceleration switch 14 based on the terminal voltages of the primers 13 and 18 and the mechanical acceleration switch 14 and their voltage differences. If it is determined that there is a disconnection, the occupant is notified using an alarm device such as a lamp in the same manner as described above. The microcomputer 10 transmits a request signal to the driver's seat airbag system 2 via a signal line X, a first communication circuit 20, a switching transistor 21, a resistor 22, a power supply line 6, and the like in series.
3, a request signal is output from the driver side airbag system 32 via the switching transistor 28, the resistor 29, the power supply line 6 and the like as a response signal in response to the request signal. Make a diagnosis. Reference numeral 17 denotes a third switch circuit, which is turned on when the microcomputer 10 receives a response signal relating to a serious collision from the microcomputer 25 of the driver side airbag system 32 to activate the driver side airbag primer 18. . Reference numeral 19 denotes a fourth switch circuit, which is the microcomputer 10 only for a predetermined time after the first switch circuit 7 is switched from the off state to the on state.
This is for rapidly charging the smoothing capacitor of the constant voltage circuit 31.

Next, the driver's seat side airbag system 3
2 will be described. An acceleration sensor 24 is the same as the longitudinal acceleration sensor 9 and has a different detection direction from the longitudinal acceleration sensor 9 and is mounted so as to detect the lateral acceleration of the vehicle. 25. The microcomputer 25 has a collision determining function similarly to the microcomputer 10 and determines the magnitude of the collision based on the acceleration signal supplied from the lateral acceleration sensor 24, and determines the determination result together with a diagnosis result described later. And the microcomputer 1 via the second communication circuit 27 as a response signal.
Output for 0.

The microcomputer 25 has a diagnostic function similarly to the microcomputer 10, performs a failure diagnosis of the left-right acceleration sensor 24 and the acceleration switch 26, and sends a first communication circuit 20 from the microcomputer 10.
Every time a request signal is supplied via the power line 6 from the
The diagnosis result is supplied as a response signal to the microcomputer 10 of the driver's seat airbag system 23 via the second communication circuit 27, the power supply line 6, and the signal line Z.

The acceleration switch 26 comprises a semiconductor acceleration sensor and a comparison circuit for inputting its detection output, and outputs a switch signal when the output from the semiconductor acceleration sensor exceeds a reference value of the comparison circuit. I do.

Reference numeral 28 denotes a switching transistor such as a field effect transistor, which is turned on and off by an output signal of the second communication circuit 27 and outputs a response signal formed from a signal indicating a collision, various diagnostic signals, and the like. Reference numeral 29 denotes a resistor inserted at a connection point between the switching transistor 28 and the power supply line 6. The resistor 29 is connected in series with the resistor 8 via the power supply line 6, and the voltage on the anode side of the backflow prevention diode 30 is switched. When the transistor 21 or 28 is turned on, the lowest level does not become 0 level but is kept at a constant voltage V1 (see FIG. 3), so that an input voltage can be always supplied to a constant voltage circuit 31 described later. The constant voltage circuit 31 always receives an input voltage,
In addition, power is supplied to each circuit constituting the driver seat side airbag system 32.

The power supply line 6 has a voltage waveform as shown in FIG. 3 when communication is performed between the driver's seat airbag system 23 and the driver's seat side airbag system 32. That is, in FIG. 3, the voltage V1 is a value obtained by dividing the output voltage V3 of the booster circuit 3 when the switching transistors 21 and 28 are turned on by the resistors 8 and 29, and the voltage V2 is determined by the switching transistor 21 (or 28). The voltage at the time of turning off is determined by the value of the resistor 8.

Next, the operation of the above configuration will be described. When the diagnostic function operates, the ignition switch 2 is turned on, the microcomputer 10 of the driver's seat airbag system 23 starts to operate, and when the capacitance diagnosis is performed, the microcomputer 10 switches the first switch via the signal line Y. The circuit 7 and the fourth switch circuit 19 are turned off, and the switching transistor 16 is turned on for a predetermined time, so that the fully charged backup capacitor 5 is discharged via the resistor 4 and the backup capacitor 5 at that time is discharged. The microcomputer 10 reads the terminal voltage of the backup capacitor 5 to determine the voltage change amount of the terminal voltage of the backup capacitor 5, and determines whether or not the capacitance is a specified value. Activate the alarm to notify you. In addition, the primers 13, 18
Diagnosis such as disconnection of the
Activate the alarm device.

Thereafter, the first switch circuit 7 is turned on, and a request signal for diagnosis is supplied to the microcomputer 25 of the driver side airbag system 32 via the first communication circuit 20 and the power supply line 6. In synchronization with the end of the transmission of the header of the request signal, the switching transistor 19 is turned on for a predetermined time period before the next data is transmitted, and the smoothing of the constant voltage circuit 31 via the power supply line 6 is performed. Quickly charge the capacitor.

The microcomputer 25 which has received the request signal operates various parts in the driver side airbag 32,
For example, by reading a terminal voltage of the lateral acceleration sensor 24 and the like, and turning on and off the switching transistor 28 by the output of the second communication circuit 27, the microcomputer 10 of the driver's side airbag system 32 through the power supply line 6 Is transmitted via the signal line Z and diagnosed by the microcomputer 10, and as a result,
If it is determined that there is a failure, the alarm device is operated in the same manner as described above.

When the collision judging function is activated When the vehicle has a frontal collision such as a rear-end collision after the above-described various diagnoses are completed (or not performed), the mechanical acceleration switch 14 of the driver's seat airbag system 23 is operated. Turns on, and when the microcomputer 10 determines that a serious collision has occurred based on the acceleration signal from the longitudinal acceleration sensor 9, the microcomputer 10 controls the second switch circuit 11 to turn on and charges the charge stored in the backup capacitor 5. Electricity is supplied to the primer 13 via the discharge diode 12 to deploy an airbag or the like in the driver's seat to protect the occupant from a forward collision.

On the other hand, the microcomputer 25 of the driver's seat side airbag system 32 includes an acceleration switch 26.
When a serious collision is determined based on the switch signal from the microcomputer and the acceleration signal from the lateral acceleration sensor 24, the signal indicating the collision is used as a response signal to the microcomputer 25.
Supplies the microcomputer 10 and turns on the third switch circuit 17 to supply the charge charged in the backup capacitor 5 to the primer 18 via the power supply line 6 to deploy the side airbag provided on the seat. To protect occupants from side impacts.

[0016]

However, in the above-mentioned structure, the power supply from one booster circuit 3 to the driver's seat airbag system 23 and the driver's seat side airbag system 32 is not required. Therefore, the booster circuit 3 must have a large power capacity, and must be configured using expensive electronic circuit components and components with high withstand voltage.

While the microcomputer 10 is diagnosing the capacity of the backup capacitor 5, the first switch circuit 7 is turned off and the driver side airbag system 3 is turned off.
Since the supply of electric power to the driver side 2 is stopped, the microcomputer 25 of the driver's side airbag system 32 must stop operating during that time, so that the driver's side airbag system 32 cannot be diagnosed, There was a problem that operation start was delayed.

Therefore, the present invention has been made in view of the above problems, and provides an in-vehicle control device which can be constituted by inexpensive small electronic components and can always supply power to the driver side airbag system 32 and the like. The purpose is to do.

[0019]

According to a first aspect of the present invention, there is provided a vehicle-mounted control apparatus comprising: a first booster circuit for boosting a battery voltage to a predetermined first voltage; and a second booster circuit lower than the first booster circuit. A second booster circuit for boosting the battery voltage, a constant voltage circuit for converting the second booster circuit to a constant voltage, main control means supplied with power from the first booster circuit to operate a main control function; At least one sub-control means which is supplied with power from a circuit via a power supply line and operates a sub-control function, wherein the main control means performs multiplex communication with the sub-control means via the power supply line. Do.

According to a second aspect of the present invention, the main and sub control means include:
It is an occupant protection means.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Embodiment 1 of the present invention will be described with reference to FIG. In FIG. 1, the same or equivalent components as those already described with reference to FIG. 2 are denoted by the same reference numerals, detailed description thereof will be omitted, and only different portions will be described below. That is, in FIG. 1, the fourth switch circuit 19 shown in FIG.
A constant voltage circuit 33 is connected in place of the switch circuit 7, and an input terminal of the constant voltage circuit 33 and a booster circuit (hereinafter, referred to as a booster circuit).
The second booster circuit 34 that outputs an output voltage of the first booster circuit 3 ′, that is, a voltage smaller than 21V, that is, 9V is connected to an input line of the first booster circuit 3 ′).

With the above configuration, the driver side airbag system 32 is always supplied with a constant voltage from the second booster circuit 34 via the constant voltage circuit 33, so that the microcomputer 25 operates simultaneously with the microcomputer 10. Since it can be started, the start of operation is not delayed. Conventionally, the constant voltage circuit 31 of the driver side airbag system 32 converts the voltage of 21V obtained by the booster circuit 3 to a large voltage to 5V.
Since the voltage had to be reduced all at once, the voltage loss was large. However, the voltage can be reduced from 9 V to 5 V, so that the voltage loss can be reduced.

[0023]

As described above, according to the first aspect of the invention, the components of the booster circuit can be composed of small electronic components for low power, so that not only the cost can be reduced but also the cost can be reduced.
The effect that the whole shape can be reduced is exhibited.

According to the second aspect of the present invention, since the overall shape is reduced, an effect is exhibited that the vehicle can be easily mounted on a vehicle having a small mounting space.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a circuit block according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of a conventional example of the present invention.

FIG. 3 is a waveform diagram of a power supply line in FIG.

[Explanation of symbols]

 7, 11, 17, 19 Switch circuit 8, 22, 29 Resistance 9, 24 Acceleration sensor 10, 25 Microcomputer 13, 18 Detonator 20, 27 Communication circuit 21, 28 Switching transistor 26 Acceleration switch

Claims (2)

[Claims] 1. A first booster circuit for boosting a battery voltage to a predetermined first voltage, a second booster circuit for boosting the battery voltage to a second voltage lower than the first booster circuit, and the second booster A constant voltage circuit for making the circuit a constant voltage; a main control means for supplying power from the first booster circuit to operate a main control function; and a power supply from the constant voltage circuit via a power supply line for operating a sub control function. An in-vehicle control device, comprising: at least one sub-control unit, wherein the main control unit performs multiplex communication with the sub-control unit via the power supply line. 2. The on-vehicle control device according to claim 1, wherein said main and sub control means are occupant protection means.