JPH0357748A - Control circuit for safety device for vehicle - Google Patents

Abstract

PURPOSE:To surely carry out control by installing an electric current control means for controlling the level of the electric current which flows in a series circuit when the corresponding electric conduction control means operates, onto each series circuit. CONSTITUTION:If an electric conduction control part 3 judges the collision of vehicles, a starting signal T1 is outputted into a circuit 10, and after the lapse of a prescribed time, a starting signal T2 is outputted into a circuit 20. An electric field effect transistor 11 (electric conduction control element) in the circuit 10 is put into ON-state from OFF state by the signal T1, and an ignition current flows into the circuit 10 from an electric power source part 4, and the level of the detection voltage generated in a detection resistor 12 rises with time, and a transistor 13 changes from an OFF state to an ON state, and the gate potential of the transistor 11 reduces, and the increase of the electric current of the circuit 10 is suppressed, and the ignition electric current at a proper level is supplied into an ignition skib 5. Therefore, even if the ignition skib 5 does not generate high resistance after ignition, an ignition electric current flows in the ignition skib in the circuit 20 having the same constitution to that of the circuit 10, in correspondence with the signal T2 by a back-up condenser 44.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a control circuit for nine vehicle safety devices, which uses a single energy source to control a plurality of vehicle safety devices.

(Prior Art) In recent years, vehicle safety devices such as airbags and seatbelt restraint devices have been put into practical use in order to protect occupants from shocks that occur during vehicle collisions. Regarding safety systems using such vehicle safety devices. In order to prevent the battery from being damaged or the terminal of the battery from coming loose, which may occur in a collision, and the safety device not being able to start, the booster circuit and the energy A/V charged by the output voltage from the booster circuit are used. A ghee reservoir capacitor is provided as a back-up circuit within the control unit. An ignition skip for a vehicle safety device, such as an air pack, is connected to the energy reservoir capacitor as a load via an ignition switch element. If airbags are installed on the driver's and passenger's sides, multiple circuits for igniting the ignition squib will be connected in parallel to the energy reservoir capacitor. In such a configuration, multiple ignition skips are ignited sequentially with a time delay, but if an ignition skip is ignited and the ignition skip does not reach a high resistance state after ignition, the remaining ignition skips It becomes impossible to ignite. In order to solve this problem, Japanese Patent Application Laid-Open No. 63-279947 discloses that a capacitor is inserted in series with the ignition squib to ensure the ignition operation of other ignition squibs even if the ignition squib does not enter a high resistance state after ignition. A circuit configuration has been proposed that allows this to be carried out. (Problem to be solved by the invention) However, in this proposed circuit, a capacitor with low loss is required to be inserted in series with the ignition skip, which increases the cost and also reduces the differential current caused by the capacitor. Since the ignition skips the ignition, it is difficult to perform reliable ignition control.

An object of the present invention is to provide a control circuit for a vehicle safety device that can solve the above-mentioned problems of the prior art. (Means for Solving the Problems) The features of the present invention for solving the above problems include energization control means provided corresponding to each activation means of a plurality of vehicle safety devices, and energization control means for these energization control means. and an energization control unit that turns on electricity in a predetermined order, and a control circuit of a vehicle safety device that sequentially supplies starting current from a predetermined energy source to the starting means at staggered times. The means and the corresponding energization control means are connected in series to form at least two parallel-connected series circuits, each series circuit having a current flowing through the series circuit when the corresponding energization control means is activated. The point is that a current control means for controlling the repe/I/t is provided. (Function) A plurality of series circuits are formed in which each starting means is connected in series with its corresponding energization control means, and these series circuits are connected in parallel, and when a vehicle collision is detected. The energization control means incorporated in each series circuit is brought into the energized state at different times in a predetermined order by the energization control section.

As a result, each starting means is sequentially supplied with starting current from the energy source. Each series circuit is provided with current control means for controlling the level of current flowing therein so that an appropriate current flows when the current flow control means enters a state where current is allowed to flow. At this time, the level of the current flowing through each series circuit is set to an appropriate level value corresponding to the purpose, and the current energy /L /
This makes it possible to effectively and appropriately supply energy to each series circuit. (Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of a vehicle safety device control circuit according to the present invention, and the control circuit 1 shown in FIG. 1 includes a sensor 2 for detecting acceleration generated in a vehicle (not shown),
The energization control section 3 is provided in response to an acceleration signal KS outputted from the sensor 2 and indicating the acceleration generated in the vehicle. The energization control section 3 is constructed using a microcomputer,
A function for performing predetermined signal processing on the acceleration signal KS to determine whether or not a vehicle has collided, and a function for distributing the driver's side air bag and the passenger's side air pack B when it is determined that a vehicle has collided. To deploy two air packs sequentially with a predetermined time difference. It has a function of outputting 2't- with the first starting signal T1 and the second starting signal following this. The first and second activation signals T output from the energization control section 3,
, T2, the power supply section 4 supplies the required starting current to the ignition skip 5, which is the starting element for the driver's side airbag person, and the ignition skip 6, which is the starting element for the passenger side airbag B, respectively. Therefore, a first circuit 10 including an ignition skip 5 and a second circuit 20 including an ignition skip 6 are connected to the power source 4 via a known safety switch 7 that is opened and closed depending on the vehicle speed, as shown in the figure. It is connected. The first circuit 10 includes a field effect transistor 11 that functions as an energization control element that is turned on and off in response to a first starting signal T, and a current detection resistor 12 connected in series with the ignition skip 5 as shown in the figure. is connected to and formed. A detection voltage v1 generated across the current detection resistor 120 is applied between the pace and the emitter of the trunk star 13. The collector of this transistor is connected to the dart of the field effect transistor l1 to form a current control circuit 15. Therefore, when the vehicle speed exceeds a predetermined value and the safety switch 7 is closed, the first activation signal T1 is output, and the first activation signal T, When the field effect transistor 1l is turned on by applying υ, the level of the current flowing into the first circuit 10 from the power supply section 4 is determined by the current control circuit 15 configured as described above. υ is kept at a predetermined value.

In order to supply a necessary and sufficient level of ignition current to the ignition skip 5 when the field effect transistor 11 is turned on, the circuit constant of the current control circuit 150 is appropriately set>B, thereby preventing excessive level ignition current is the first
No current flows through the circuit 10, and a current sufficient for ignition is supplied to the ignition squib 5 at the required timing.

Although the first circuit 10 has been explained above, the ignition squib 6t
- The second circuit 20 including the second circuit 20 is also constructed in the same way as the first circuit 10. That is, when the second activation signal T2 is applied to the field effect transistor 21 via the resistor 24 in the second circuit 20, the field effect transistor 1
1 is turned on, and the current control circuit 25 composed of the current detection resistor 22 and the transistor 23 supplies an ignition current of an appropriate level necessary and sufficient to ignite the ignition squib 6 to the power supply section 4. It flows into the second circuit 20 from there.

Since the current detection resistors 12 and 22 are inserted in series with the ignition squibs 5 and 6, it is recommended that these resistance values be appropriately set to extremely small values so that the loss in the current detection resistors does not become large. desirable. The power supply section 4 includes a battery 41, a booster circuit 42, and a large-capacity capacitor 44 to which the high voltage output from the booster circuit 42 is applied as a charging voltage via a diode 43t to a certain backup circuit 45. have. The positive electrode of the battery 41 whose negative electrode is grounded is a diode 46.
One terminal of the capacitor 44 of the pack add circuit 45 is connected to the safety switch 7 through the safety switch 7.
connected directly to.

Therefore, normally, the battery 41 and the capacitor 4
Ignition current can be supplied from both of 4 to ignition skips 5 and 6,
In the event of a failure such as dislodgement of the battery terminal due to a vehicle collision, ignition current can be supplied to each ignition skip using the electrical energy stored in the capacitor 44.

Next, the operation of the control circuit 1 shown in FIG. 1 will be explained. When the traveling speed of the vehicle exceeds the predetermined ItL, the safety switch 7
is closed, and the first and second circuits 1 serve as loads for the power supply section 4.
0.20 is connected in parallel to the output side of the power supply section 4. If a vehicle collision is determined by the energization control section 3, first the first activation signal T is output, and then the second activation signal T2 is output after a predetermined time delay. By applying the first starting signal T, the field effect transistor 11 of the first circuit 10 is turned from the off state to the on state, and an ignition current flows into the first circuit 10 from the power supply section 4. This current also flows through the detection resistor 12, and the detection voltage v8 generated there
As time passes, the level of transistor 13 increases.
changes from off state to on state. This lowers the collector potential of the transistor 13, that is, the r-} potential of the field effect transistor 11, and suppresses an increase in the current in the first circuit 10. As a result, the current for causing the first circuit 10 to ignite the ignition squib 5 momentarily rises to a large level in response to the application of the first starting signal T, but this is suppressed by the above-mentioned current control operation. An appropriate level of current necessary for ignition is supplied to the ignition squib 5, that is, the first circuit 10, and an excessive level of current does not flow from the power supply section 4 to the first circuit 10. After the ignition skip 5 is ignited and the driver's seat side air pack A is deployed as described above, the second activation signal T2 is output.
The second circuit 20 stores the second activation signal T2 and supplies the ignition skip 6 with an appropriate level of ignition current in the same manner as the first circuit 10.

According to such a configuration, the current supplied to each ignition squib is a constant current value, so even if, for example, the ignition skip 5 does not have high resistance after ignition and enters the seat state, , the current flowing into the first circuit 10 does not become excessive. Therefore, the second activation signal T2
When the ignition current is applied to the ignition squib 6 in response to the ignition squib 6, the ignition current level of the ignition squib 60 decreases due to the excessive current flowing in the first circuit 10, making it impossible to ignite. It can be prevented. This is particularly effective during backup control in which the ignition skip ignition operation is performed only by the electrical energy stored in the co/capacitor 44.

Furthermore, by controlling the ignition current to the ignition skip with a constant current, it is possible to prevent the level of the ignition current from changing significantly even if there is circuit resistance such as a wire harness, contact resistance, etc. Since the field effect transistor or other appropriate element used as the element can be small, such as the maximum rating, a reduction in cost can be expected.

In addition, since the required fire current energy per circuit can be easily calculated, even if there are three or more airbags, it is easy to calculate the electrical energy required for each circuit, making circuit design extremely easy. It becomes easy. In addition, the capacitor capacity for the backup power supply is also smaller than in the past, which helps reduce costs.

Furthermore, even if a failure occurs in which the transistor 23 becomes OFF, it is possible to ignite the squib. On the other hand, G2
If the transistor 23 goes into a shut-down state, it can be detected from the level of its drain voltage when checking the field effect transistor 21.

In the above embodiment, the case where two air packs are controlled has been explained, but the present invention can also be applied when controlling three or more air packs by connecting the third, fourth, etc. circuits in parallel. can be applied in the same way. 1. In order to control the ignition current at a constant current, in the above embodiment, an example was shown in which the conductivity of the field effect transistor for energization control was controlled in accordance with the voltage generated in the detection resistor. The structure of the present invention is not limited to the structure of this embodiment, and the ignition current for ignition skip may be controlled at constant current by other means. (Effects of the Invention) According to the present invention, as described above, since the starting current for starting the safety devices is controlled by constant current, wastage of energy/L/Gy is suppressed and multiple safety devices can be operated reliably. It can be activated. In addition, not only will circuit design become easier, reliability will be improved due to the effects of wiring resistance and contact resistance, and cost reductions can be expected.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention. 1...
・Control circuit, 3... Energization control section, 4... Power supply section, 5
．． 6...Ignition squib. 10...first circuit, 11.2
1... Field effect transistor. 15.25... Constant current control circuit, 20... Second circuit, A... Driver's seat side air bag, B... Passenger seat side air bag, T,... First activation signal, T2 ---Second activation signal.

Claims (1)

[Claims] 1. It has an energization control means provided corresponding to each activation means of a plurality of vehicle safety devices, and an energization control section that energizes these energization control means in a predetermined order; In a control circuit for a vehicle safety device that sequentially supplies electrical energy for starting from a predetermined energy source at staggered times, at least two parallel-connected starting means and corresponding energization control means are connected in series. A vehicle comprising a series circuit, each series circuit being provided with current control means for controlling the level of current flowing through the series circuit when the corresponding energization control means is activated. Safety device control circuit.