JP3975554B2 - Crew restraint system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an occupant restraint device, and more particularly to an occupant restraint device that can avoid the influence of noise with a simple shield structure using a plurality of the same sensors.
[0002]
[Prior art]
Conventionally, in an occupant restraint device mounted on a vehicle, G sensors for detecting an impact at the time of collision are distributed and arranged in a center console portion, a door portion, etc. of the vehicle, and the degree of impact at each portion is set at one place. Is monitored by a control unit provided in the vehicle, and whether or not the vehicle collides is determined by a predetermined calculation to determine whether or not to deploy the airbag module.
[0003]
In recent years, in order to secure the degree of freedom of layout of various units, reduce the number of harnesses, etc., it has been desired to control the airbag module of each unit with a unit having a plurality of G sensors and control units provided in one place. .
[0004]
[Problems to be solved by the invention]
However, when a plurality of G sensors are arranged in one unit, when each G sensor is affected by external noise, in order to separate a voltage signal due to impact from a voltage signal affected by the external noise, It is necessary to add a filter circuit and a noise removal circuit for reducing the influence of external noise to the voltage signal from each G sensor, which complicates the circuit configuration and increases the manufacturing cost.
[0005]
The present invention has been made in view of the above, and an object of the present invention is to provide an occupant restraint device having noise resistance performance similar to that of a conventional one at a low cost even when external noise is added. .
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 has an acceleration sensor for detecting the degree of impact applied to the vehicle, and if it is determined from the output signal of the acceleration sensor that the vehicle has collided, An occupant restraint device that deploys an air bag module in a room, which is substantially the same as the first acceleration sensor covered by a shield case that blocks external noise and the first acceleration sensor that is not covered by the shield case. A second acceleration sensor provided adjacent to the first acceleration sensor and substantially the same as the first acceleration sensor, and a signal output from the first acceleration sensor is equal to or greater than a predetermined reference value, and the second acceleration sensor And the difference value between the signal output from the first acceleration sensor and the signal output from the second acceleration sensor is a predetermined value. If it is less than the threshold value, and summarized in that a control means for deploying the air bag module.
[0007]
【The invention's effect】
According to the first aspect of the present invention, the output signal from the first acceleration sensor covered with the shield case that blocks external noise is not less than the predetermined reference value and is not covered with the shield case. An output signal of a second acceleration sensor that is provided substantially adjacent to the first acceleration sensor and is substantially the same as the first acceleration sensor is equal to or greater than a predetermined reference value, and an output signal of the first acceleration sensor By deploying the airbag module when the difference value from the output signal of the second acceleration sensor is less than a predetermined threshold, the influence of external noise applied to substantially the same acceleration sensor can be canceled. .
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0009]
FIG. 1 is a diagram showing a configuration of an occupant restraint device according to an embodiment of the present invention.
[0010]
As shown in FIG. 1, an occupant restraint device 1 is provided with a battery 3 that is mounted on a vehicle and supplies power to an electronic device, an ignition switch IGN_SW5 that is turned on when the engine is started, and a G sensor. A printed circuit board 7; a shield case 9 for covering the G sensor 11 to avoid the influence of external noise; and G sensors 11 and 13 comprising substantially the same semiconductor elements that output a voltage signal in accordance with the degree of impact applied to the vehicle. When the vehicle collides, the power supply circuit 15 that stabilizes the power supply voltage supplied from the battery 3, the CPU 17 that determines whether or not the vehicle has collided based on the voltage signals output from the G sensors 11 and 13 An ignition transistor that outputs an ignition current to the squib 19 in accordance with an ignition signal (High level) output from the output terminal Vo of the CPU 17. And stannous TR, and a to squib 19. deploy the air bag module (not shown) when the ignition current is applied.
[0011]
The G sensors 11 and 13 are provided on the printed circuit board 7 substantially adjacent to each other.
[0012]
2A and 2B are an external view (a) of the shield case 9 covering the G sensor 11, a top view (b) of the printed circuit board 7 viewed from above the mounting surface, and a bottom view (c) of the printed circuit board 7 viewed from the solder surface. ).
[0013]
The shield case 9 is a case in which a material such as phosphor bronze is rolled and formed, and is a member having an effect of preventing the transmission of external noise by grounding. As shown in FIG. 2A, a plurality of leads 31 are provided at the bottom of the shield case 9, and are opened to cover the G sensor 11 attached to the printed circuit board 7 shown in FIG. The lead 31 of the shield case 9 is inserted into the lead hole 33. The lead 31 of the shield case 9 inserted into the lead hole 33 of the printed circuit board 7 is solid-grounded on the solder surface on the printed circuit board 7 as shown in FIG. As a result, the G sensor 11 is covered with the shield case 9 and the printed circuit board 7 and can avoid the influence of external noise.
[0014]
Next, referring to FIG. 4, the operation of the occupant restraint device will be described based on the processing functions (S10 to S60) of the CPU shown in FIG. Note that the G sensors 1 and 2 shown in FIG. 3 are the G sensors 11 and 13, respectively, and will be described using the G sensors 1 and 2 in the following description.
[0015]
First, in the algorithm 1 shown in the processing function S10, when the voltage signal output from the G sensor 1 is greater than or equal to a predetermined reference value, it is determined that the vehicle has collided, and the voltage signal output from the G sensor 1 is If it is below this reference value, it is determined as a noise level. Next, in the algorithm 2 shown in the processing function S20, when the voltage signal output from the G sensor 2 is equal to or greater than a predetermined reference value, it is determined that the vehicle has collided, and the voltage signal output from the G sensor 2 Is less than this reference value, it is determined as a noise level.
[0016]
Next, in the integration process shown in the processing function S30, the previous value and the current value of the voltage signal output from the G sensor 1 are added to obtain the current integrated value. As a result, as shown in FIG. 4A, when an impact is applied to the G sensor 1, the level is as shown by a broken line (A). When the G sensor 1 senses noise that has been lowered by the shield case, the level is indicated by a solid line (b).
[0017]
Next, in the integration process shown in the processing function S40, the previous value and the current value of the voltage signal output from the G sensor 2 are added to obtain the current integrated value. As a result, as shown in FIG. 4B, when an impact is applied to the G sensor 2, the level is shown by a solid line (c). Similarly, when the G sensor 2 senses a high level of external noise, the level is indicated by a solid line (c). That is, even if an integration process is performed on the voltage signal output from the G sensor 2, it cannot be distinguished whether the G sensor 2 is subjected to an impact at the time of a collision or whether a high level external noise is detected. .
[0018]
Here, in the difference processing shown in the processing function S50, the difference value between the two is obtained by subtracting the integration value obtained in the integration processing S30 from the integration value obtained in the integration processing S40. As a result, as shown in FIG. 4C, when an impact is applied to the G sensors 1 and 2, the level indicated by the solid line (d) is obtained, and a difference value lower than a predetermined threshold line is output. Therefore, it is determined as an impact generated at the time of collision. On the other hand, as shown in FIG. 4D, when the external noise is occurring, the level is shown by a solid line (e), and a difference value higher than a predetermined threshold line is output. To do.
[0019]
Next, in the logical product process shown in the processing function S60, a logical product is obtained based on the determination result values in the algorithms 1 and 2 and the determination result value in the difference process S50.
[0020]
As a result, when an impact applied to the vehicle at the time of collision is detected by the G sensors 1 and 2, a logical value “1” representing an ignition signal is output from the logical product processing S60. That is, when the vehicle collides, the transistor TR is turned on in response to an ignition signal (High level) output from the output terminal Vo of the CPU 17, an ignition current flows through the squib 19, and the squib 19 is heated to form an airbag module. (Not shown) will expand.
[0021]
On the other hand, when noise is applied to the G sensor, a logical value “0” representing non-operation is output from the logical product processing S60. That is, the transistor TR is in an off state.
[0022]
As described above, the G sensor 11 having the shield case 9 for avoiding the influence of the external noise and the G sensor 13 which is under the influence of the external noise and is provided substantially adjacent to the G sensor 11 are respectively output. When the difference value between the voltage signals is less than a predetermined threshold value, the CPU 17 performs a difference process S50 for determining that the vehicle has collided, and arranges them on the same printed circuit board 7 so that substantially the same G sensor. The influence of the external noise applied to 11 and 13 can be canceled. As a result, it is possible to provide an occupant restraint device having noise resistance performance similar to that of the conventional one with a simple configuration and at low cost.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an occupant restraint device according to an embodiment of the present invention.
2A is an external view of a shield case 9 covering the G sensor 11, FIG. 2B is a top view of the printed circuit board 7 viewed from above the mounting surface, and FIG. 2C is a bottom view of the printed circuit board 7 viewed from the solder surface. ).
FIG. 3 is a diagram for explaining processing functions (S10 to S60) of a CPU.
4A is a diagram showing an integrated value of the G sensor 1, FIG. 4B is a diagram showing an integrated value of the G sensor 2, FIG. 4C is a diagram showing a differential value at the time of impact, and FIG. FIG.
[Explanation of symbols]
9 Shield case 11, 13 G sensor 17 CPU
19 Squibb

Claims (1)

An occupant restraint device that has an acceleration sensor for detecting the degree of impact applied to the vehicle and deploys an airbag module in the passenger compartment when it is determined from the output signal of the acceleration sensor that the vehicle has collided,
A first acceleration sensor covered with a shield case that blocks external noise;
A second acceleration sensor provided substantially adjacent to the first acceleration sensor in a state not covered by the shield case, and substantially the same as the first acceleration sensor;
The signal output from the first acceleration sensor is greater than or equal to a predetermined reference value, and the signal output from the second acceleration sensor is greater than or equal to a predetermined reference value and is output from the first acceleration sensor. An occupant restraint device comprising: control means for deploying the airbag module when a difference value between the signal to be output and the signal output from the second acceleration sensor is less than a predetermined threshold value.

Images