JPH0848208A - Collision sensor - Google Patents

Abstract

PURPOSE:To operate a crew protection device exactly and enable tuningless by calculating a relative velocity of the crew in relation to a vehicle at the time of a specific distance movement by a relative velocity calculation means, in a collosion sensor for outputting an operation signal to the crew protection device. CONSTITUTION:The airbag 6 of a crew protection device is started by an acceleration meter 1 through a calculation circuit 3. The calculation circuit 3 calculates a velocity V by the time integration of an acceleration signal G in a block 71 which is a time integration means. Further, the moving distance S of the crew is calculated by the time integration of a velocity V in a block 72 which is the time integration means. The relation between an elapsed time fsn and the moving distance FTn of the crew is calculated in a block 90 by using the velocity V, acceleration G, revised acceleration change JJ inputted respectively from the blocks 71, 31, 74. The elapsed time corresponding to a prescribed moving distance so, namely a time FT upto a secondary collosion is calculated in a block 91 and the crew velocity FV after moving a prescribed distance is calculated in a block 92 by using a time FT upto the secondary collosion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a collision sensor used in a vehicle occupant protection system, and more particularly to a collision sensor capable of tuning-free.

[0002]

2. Description of the Related Art A conventional electronic collision sensor of this type is
It was necessary to determine the threshold value for determining the sensitivity for each vehicle type, and it was necessary to spend a great deal of money and time for the tuning and confirmation experiments. For this reason, various proposals have been made to eliminate tuning.

As one of such techniques, Japanese Patent Laid-Open No.
Japanese Patent No. 85298 discloses an operation control device for an occupant protection device. The operation control device for the occupant protection device includes means for calculating the relative speed of the occupant with respect to the vehicle after a lapse of a predetermined time based on the acceleration detected by the acceleration sensor, and the occupant protection device when the relative speed is equal to or higher than a threshold value. An operation necessity determination means for determining that it should be operated, a means for calculating a relative movement distance of an occupant with respect to a vehicle after a lapse of a predetermined time based on acceleration, and an operation of the occupant protection device based on the relative movement distance of the occupant. The operation timing determining means for determining the timing to be operated, and the output means for outputting the operation signal to the occupant protection device at the timing determined by the timing determining means when the operation necessity determining means determines that the operation should be performed. I have. According to this actuating device, it can
The degree of injury due to the next collision is judged based on the predicted relative speed of the occupant with respect to the vehicle to determine whether or not the airbag (occupant protection device) should be activated, and the occupant after the time required to deploy the airbag. By calculating the amount of movement of the air bag, the operation timing is determined so that the airbag is sufficiently deployed before the occupant is received. This makes it possible to accurately determine whether or not the airbag should be operated, to appropriately determine the timing of the operation, and to make tuningless.

[0004]

However, it is inherently not easy to judge whether or not the operation is necessary because it is required to be performed in real time while predicting the subsequent transition from the collision waveform, and at the early stage of the collision. When the degree of injury due to the secondary collision of the occupant is determined based on the predicted relative speed as described above to determine whether or not the operation is required, highly accurate prediction of the relative speed and quick calculation processing are required. By the way, in the above-mentioned operation control device, the predicted value of the relative speed at the time of the secondary collision is the value after a predetermined time has passed, but since the time from the present time to the occurrence of the secondary collision varies depending on the speed of the collision, the relative speed is predicted. There is a problem that the value error becomes large.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a relative speed when a predetermined distance of an occupant moves based on an acceleration signal and a predetermined time elapses. It is an object of the present invention to provide a collision sensor capable of accurately operating the occupant protection device by predicting the relative movement distance of the rear occupant and determining the necessity and timing of the operation and enabling tuningless.

[0006]

In order to solve the above-mentioned problems, a collision sensor according to the present invention calculates an acceleration detecting means for detecting an acceleration of a vehicle and a relative speed of an occupant with respect to the vehicle based on the detected acceleration. Means for determining whether or not the occupant protection device should be activated when the relative speed of the occupant is equal to or greater than a threshold value, and an occupant for the vehicle after a predetermined time has elapsed based on the detected acceleration. Means for calculating the relative movement distance of the occupant, operation timing determination means for deciding the timing at which the occupant protection device should be activated based on the relative movement distance of the occupant, and the operation necessity determination means for deciding that the occupant protection apparatus should be activated Collision sensor having an output means for outputting an operation signal to the occupant protection device at the timing determined by the timing determination means. Oite, the relative speed calculating means is for calculating a relative speed to the vehicle at a predetermined distance movement of the occupant.

Further, when the relative speed of the occupant becomes equal to or higher than the threshold value after the operation timing determined by the operation timing determination means, the relative speed is equal to or lower than the second threshold value higher than the threshold value. Therefore, when the relative movement distance of the occupant is equal to or larger than the predetermined value, the operation signal may not be output.

[0008]

The relative speed with respect to the vehicle when the occupant moves a predetermined distance is calculated based on the acceleration, and this relative speed is compared with a threshold value to determine whether the operation is necessary. Since the predicted value of the relative speed is the value when moving a predetermined distance from the present time, it is not affected by the speed of collision.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. Although the deceleration side acceleration is described as a positive value here, making it negative has the same effect if the positive and negative logics in each block are matched.
1 is a block diagram showing the configuration of the collision sensor of the present invention, FIG. 2 is a control diagram showing the processing of the arithmetic unit of FIG. 1, FIG. 3 is an acceleration graph showing the effect of the collision sensor of FIG. 1, and FIG. It is a block diagram which shows the structure of the other Example of the collision sensor of invention.

First, the configuration will be described with reference to FIG. FIG.
In, the accelerometer 1 is connected to the reset circuit 4 and the trigger circuit 5 via the arithmetic circuit 3. Then, the trigger circuit 5 starts the airbag 6, which is an occupant protection device. Next, the arithmetic circuit 3 will be described. Block 11
At time t0, the time t0 when the acceleration G measured by the accelerometer 1 exceeds a predetermined acceleration G1 is determined. At block 31, a low pass filter is passed. This low-pass filter is inserted to remove noise and clarify the acceleration waveform, and its characteristics are appropriately determined according to the specifications of the collision sensor and the like. In a block 32 which is an acceleration change calculation means, an acceleration change F1 = ΔG / Δt per unit time of the acceleration signal G which has passed through the low pass filter 31 is calculated. In the block 88 which is the dividing means, the acceleration G is output as the first wave G _P until the acceleration change F1 changes from a positive value to a negative value and then becomes zero. In the block 87 which is the peak acceleration change calculating means, the first wave G
Acceleration from time t0 of _P calculates the peak change in acceleration up to the time t _P which is a (maximum _{acceleration) ΔG P / (t P -t0} ). The dividing means 33 and the peak acceleration change calculating means 87 constitute the first wave physical quantity calculating means 37. In block 74, the peak acceleration change ΔG _P / (t _P −
The acceleration change F1 output from the block 32 is corrected using t0) to calculate the corrected acceleration change JJ. This first
The wave physical quantity calculation means 37 is for more accurately determining whether or not the operation is necessary, paying attention to the fact that the physical quantity of the first wave of the collision waveform is larger as the collision speed is higher, and can be omitted. The output from the first wave physical quantity calculating means 37 is input to the acceleration change calculating means 74 to make an excessive / under-evaluation of an acceleration change used for calculating an occupant speed FV and an occupant movement amount FS described later.

On the other hand, in a block 71 which is a time integrating means, the acceleration signal G is time integrated to calculate a velocity V. Further, in block 72 which is a time integration means,
This speed V is integrated over time to calculate the movement amount S of the occupant.
In block 75, velocity V, acceleration G, and modified acceleration change J input from blocks 71, 31, and 74, respectively.
The relationship between the elapsed time fsn and the movement amount FTn of the occupant is calculated using J. In block 91, a predetermined moving distance S ₀ (block 93) is used to calculate an elapsed time corresponding to this moving distance S ₀ , that is, a time FT until a secondary collision. In block 92, time FT until secondary collision
Occupant speed FV after moving a predetermined distance (at the time of secondary collision) using
To calculate. In the block 76 which is the occupant movement amount calculation means, the occupant movement amount after a predetermined time is calculated using the movement amount S, the velocity V, the acceleration G, and the acceleration change F1 which are respectively input from the blocks 72, 71, 31, 32. Calculate FS. In a block 79, which is an operation necessity determination means, the occupant speed FV is set to a preset reference value (threshold value) F.
Compared with V1 (block 80), if the occupant speed FV is greater than or equal to the reference value FV1, the first operation signal is output. In a block 81 which is an operation timing calculating means, the passenger movement amount FS is set to a preset reference value FS1 (block 8).
Compared with 2), if the occupant movement amount FS is greater than or equal to the reference value FS1, the second operation signal is output. In the block 84, which is the first AND means, when both the first and second actuation signals are input, the third actuation signal is output. On the other hand, in block 83, which is a comparison means, the speed (deceleration amount) V input from block 71 is compared with a preset reference value V1, and if the speed V is equal to or greater than the reference value V1, a fourth operation signal is output. Output. The comparison means 83 determines whether or not the acceleration signal is a rough road pulse. Second
In block 85, which is an AND means, when both the third and fourth actuation signals are input, a fifth actuation signal is output to the trigger circuit 5. When the fifth activation signal is input, the trigger circuit 5 activates the airbag 6. A block 73 calculates a subtraction integral value V3 by subtracting a predetermined value ΔV per unit time, and a block 78 outputs a signal to the reset circuit 4 when the subtraction integral value V3 is near zero. All calculations in are reset.

Next, the block 90 of the arithmetic circuit 3 described above.
The operation of .about.92 and 76 will be described based on the contrast diagram of FIG. 2 and the graph diagram of FIG. In FIG. 2, in block 90,
The occupant speed FV and the occupant movement amount fsn after an arbitrary time FTn from the present time are calculated by the following formulas. fsn = S + V × FTn + 1/2 × G × (FTn) ² + 1/6 × JJ (FTn) ³ ... In this embodiment, a case where three points are obtained will be described for simplicity of explanation. FT1 = 10 ms as arbitrary 3 points in the above equation
When ec, FT2 = 20 msec and FT3 = 30 msec are given, for example, fs1 = 6, fs2 = 8, fs3 = 9
Is obtained. In the above description, the occupant movement amount fsn
Although an approximate calculation is used to calculate, the time FTn can be calculated by calculating a function for the time FTn when the expression is simplified and a simple expression is used.

In block 91, a predetermined passenger movement distance S
_If the distance between the driver's seat and the steering wheel is set to ₀ , and is 8 inches, for example, the time FT until the secondary collision is FT.
= FT2 = 20 msec. When the set value S ₀ is in the middle of the movement amount fsn, it is calculated by proportional calculation.

In block 92, the occupant speed FV after the movement of the predetermined distance S _{0 is} calculated by the following equation. FV = V + G × FT + 1/2 × JJ × (FT) ² ... In the case of the above example, FV = V + G × (20) + 1/2 × JJ ×
(20) ² , which allows the occupant speed FV after the predetermined distance is moved.

In block 76, the airbag deployment time Δt is set as a predetermined time, and the occupant movement amount FS after this deployment time Δt is calculated by the following formula. FS = S + V × Δt + 1/2 × G × (Δt) ² + 1/6 × JJ (Δt) ³ ...

Next, the effect of the above-mentioned collision sensor will be described with reference to FIG. 3, which schematically shows the collision waveform. In FIG. 3, the collision waveform varies depending on the form of the collision. For example, the waveform H of the high-speed collision has a shorter time from the collision occurrence to the completion of the collision, that is, the secondary collision occurrence than the waveform L of the low-speed collision. When these collisions waveform is inputted to the collision sensor described above, when the high-speed collision (H) is FT _H is calculated as the predicted value as the time from the present time t to the secondary collision is because actual a (predicted value The result is not necessarily the same), and in the case of a low speed collision (L), FT _L is calculated to be in accordance with the collision waveform. As shown in the figure, this is conventional, and is constant at Δt regardless of the collision waveform. Then, using this time, the occupant speed at the time of the secondary collision occurs is calculated by an equation, so that it can be predicted more accurately than in the conventional case.

Next, another embodiment will be described with reference to FIG. In FIG. 4, the difference from FIG. 1 is that two reference values FV1, FV2, FS1, FS2 are set in the operation necessity determination means 98 and the operation timing determination means 95, respectively, and the output circuits are correspondingly set. That is, two AND means (93, 94) are provided. That is, the operation necessity determination means 98 determines that the occupant speed FV is the first reference value FV.
If it is 1 or more, an activation signal is sent to the first AN on line 99.
It outputs to the D means 93, and when it becomes the second reference value FV2 or more, the operation signal is output to the third AND means 94 in the line 100. On the other hand, the actuation timing determination means 95 outputs an actuation signal to the third AND means 94 in the line 102 when the occupant movement amount FS is greater than or equal to the first reference value FS1 and less than FS2, and in the line 101 when it is greater than or equal to the second reference value FS2. The operation signal is output to the first AND means 93. Therefore, after the occupant speed FV exceeds the first reference value FV1 and the operation necessity determination means 98 outputs an operation signal, the occupant movement amount F
When S exceeds the first reference value FV1, AND means 9 is activated at the time when the operation timing determining means 95 outputs the operation signal.
The occupant movement amount FS exceeds the first reference value FS1 and the operation timing determining means 95 outputs the operation signal, and then the occupant speed F is output.
When V exceeds the first reference value FV1, the occupant movement amount FS
Is greater than or equal to the second reference value FS2, or the occupant speed FV
Is less than the second reference value FV2, the operation timing determination means 95 or the operation necessity determination means 98 to the third AN, respectively.
No operation signal is output to the D means 94, and the airbag is not deployed. That is, the secondary collision speed is not very fast,
In addition, when the occupant is too close to the dashboard (handle), the airbag is not deployed, which prevents the occupant from being injured by punching the airbag.

[0018]

As described above, the collision sensor of the present invention has a relative speed calculating means for the vehicle when the occupant moves a predetermined distance, an operation necessity determining means based on the relative speed, and a relative occupant relative to the vehicle after a predetermined time has elapsed. When the travel distance calculation means, the operation timing determination means based on the relative travel distance, and the operation necessity determination means determine that the operation should be performed, the operation signal is sent to the occupant protection device at the timing determined by the timing determination means. Since the output means for outputting is provided, the predicted value of the relative speed is the value at the time of moving a predetermined distance from the present time, and is not affected by the speed of the collision. For this reason, the relative speed of the occupant in the secondary collision can be predicted more accurately than in the conventional case, and the occupant protection device can be operated accurately to realize tuningless.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a collision sensor of the present invention.

FIG. 2 is a control diagram showing a process of the arithmetic unit of FIG.

FIG. 3 is an acceleration graph showing an effect of the collision sensor of FIG.

FIG. 4 is a block diagram showing the configuration of another embodiment of the collision sensor of the present invention.

[Explanation of symbols]

 FV1 1st reference value (threshold value) FV2 2nd reference value (threshold value) FS1 1st reference value (threshold value) FS2 2nd reference value (threshold value) 1 Accelerometer (acceleration sensor) 76 Occupant movement Quantity calculation means (relative movement distance calculation means) 79 Actuation necessity judgment means 81 Actuation timing determination means 84 First AND means (output means) 85 Second AND means (output means) 90 blocks (relative speed calculation means) 91 blocks (relative speed) Calculation means) 92 Block (relative speed calculation means) 93 First AND means (output means) 94 Third AND means (output means) 95 Operation timing determination means 98 Operation necessity determination means

Claims (2)

[Claims] 1. An acceleration detecting means for detecting an acceleration of a vehicle, a means for calculating a relative speed of an occupant with respect to the vehicle based on the detected acceleration, and an occupant protection device when the relative speed of the occupant is equal to or more than a threshold value. Activating necessity determination means for determining whether to operate the vehicle, means for calculating a relative movement distance of the occupant with respect to the vehicle after a predetermined time has elapsed based on the detected acceleration, and the occupant based on the relative movement distance of the occupant. To the occupant protection device at the timing determined by the operation timing determination means for determining the timing at which the protection device should be activated, and when the operation necessity determination means determines that the protection device should be activated. In a collision sensor having output means for outputting an actuation signal, the relative speed calculation means is provided to the vehicle when the occupant moves a predetermined distance. A collision sensor characterized in that it calculates a relative speed with respect to the collision sensor. 2. When the relative speed of the occupant becomes greater than or equal to the threshold value after the operation timing determined by the operation timing determination means, the relative speed is less than or equal to a second threshold value greater than the threshold value. The collision sensor according to claim 1, wherein when the relative movement distance of the occupant is equal to or larger than a predetermined value, no operation signal is output.