JP3159279B2 - Collision sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a collision sensor suitable for detecting a collision of a vehicle used in a starting system of an occupant protection device such as an airbag.

[0002]

2. Description of the Related Art Conventionally, collision sensors suitable for detecting a collision of a vehicle used in a starting system of an occupant protection device such as an airbag are classified into a sensor using a sensing mass and an electronic sensor using an accelerometer. You. As an electronic type, there is known an electronic type in which an acceleration waveform from an accelerometer is time-integrated, and when the time integrated value exceeds a predetermined value, an occupant protection device such as the airbag is started. (See, for example, US Pat. No. 3,701,903). Further , as a modified example, before performing time integration, by subtracting a constant acceleration from the acceleration waveform, when an acceleration waveform that does not cause injury to the occupant such as when the vehicle is traveling on an uneven road is input. There is also a device designed to prevent the occupant protection device from starting (see Japanese Patent Application Laid-Open No. 49-55031).

[0003] However, the above-mentioned collision sensor cannot always start the occupant protection device within the start request time required for all types of collisions predicted for the actual vehicle. In particular, the acceleration waveform of the low-speed frontal collision, such as starting of the occupant protection apparatuses is not required, the startup speed oblique collision or pole collision required of the occupant protection apparatus (those impinging on the pole), the occupant protection It is very similar at the start request time of the device, and it is difficult to determine. That is, FIG.
As shown in the figure, the acceleration waveform (shown by a dotted line) of the low-speed head-on collision that does not require the start of the occupant protection device and the acceleration waveform of the high-speed diagonal collision that requires the start of the occupant protection device The acceleration waveform (shown by a solid line) is very similar to the start request time (between) when it is necessary to determine whether to start the occupant protection device. Therefore, as shown in FIG. 9, even if the collision sensor subtracts a constant acceleration from the acceleration waveform and integrates the subtracted acceleration with time (V1 '), the collision sensor discriminates them and starts the airbag within the start request time. It is difficult to make it happen. As a result, when the starting condition is prioritized, unnecessary starting for a low-speed head-on collision is caused. Conversely, if the non-start condition is prioritized,
There has been a problem that starting is delayed due to a high-speed oblique collision or the like, and non-starting is caused.

In view of this, the applicant has disclosed in Japanese Patent Application No. 2-74457 (Japanese Patent Application Laid-Open No. 3-253441) that a collision of a vehicle is detected from an acceleration waveform of an accelerometer, and an occupant protection device such as an airbag is provided by a trigger circuit. A collision sensor to be started, an integration means for performing a peak cut of a predetermined value or less on the acceleration waveform and performing time integration, a subtraction means for subtracting a time integration value of a predetermined function from the integration value; There has been proposed a collision sensor including first comparing means for comparing a value with a predetermined time function value. The operation principle of this collision sensor is as follows. Previously not a, both the acceleration waveform of the low-speed head-on collision and high speed oblique collision, in the average acceleration of the collision initial portion is the time start request, is almost equivalent, high speed oblique collision, as shown in FIG. 8 The acceleration waveform has a considerable vibration component due to buckling, vibration, and the like of the vehicle body. On the other hand, since most of the impact energy of the low-speed head-on collision is absorbed by an energy absorbing device such as a bumper, the vibration component is not so large. Paying attention to the difference between the characteristics of the two acceleration waveforms, the one obtained by removing the valley of the acceleration waveform is time-integrated to obtain a subtraction integrated value. As shown in FIG. 3, the subtraction integral value of the acceleration of a high-speed oblique collision having a large vibration component is a large value as compared with a value obtained by simply subtracting a constant acceleration and integrating over time. Can be performed reliably.

[0005]

However, in recent years,
The demand level for preventing malfunction of the airbag when the vehicle is running on a bumpy road (hereinafter referred to as rough road) has become strict, and it has become necessary to deal with this. Among such demands, in the case of particularly severe rough road, it may issue a vibration component for bottoming of the body is. As shown in FIG. 10A, the vibration component due to the bottoming of the body occurs at the same time as the start request time of the airbag. in this case,
In the above-described collision sensor, the one obtained by removing the valley portion of the acceleration waveform is time-integrated to obtain a subtraction integral value. Therefore, the subtraction integral value V1 is, as shown in FIG. In some cases, the operation tends to be determined.

[0006] Also, collision wave of an automobile as shown in FIG. 11 (a), it is generally a wave with 2-3 undulation 80 and 81. Therefore, the subtraction integral value V1 is also calculated as shown in FIG.
As shown in (b), the wave has undulations 82 and 83, and the subtraction integral value V1 is earlier than the start request time 84.
Has reached a predetermined time function 62 (reference numeral 82), and the operation may be early. Also , as shown in FIG. 12A, if the first undulation 84 is not so large,
As shown in (b), the subtraction integral value V1 is changed to the start request time 8
4 could not catch this swell 85, and had a problem that it would not operate.

[0007] The present invention, which has been made in view of such problems of the prior art, and an object, not the usual high-speed oblique collision or pole collision only in severe rough road Another object of the present invention is to provide an electronic collision sensor that can prevent malfunction and can control the operation timing to prevent early operation or non-operation of a wider range of collision waves.

[0008]

In order to solve the above-mentioned problems, a collision sensor according to the present invention detects a collision of a vehicle from an acceleration waveform of an accelerometer and activates an occupant protection device such as an airbag by a trigger circuit. A sensor,
A peak cut means for performing a peak cut of a predetermined value or less on the acceleration waveform, a first integration means for time-integrating a peak cut waveform obtained by the peak cut means, and a first product
The first function of the predetermined function is calculated from the first time integration value obtained by the minute means .
A first subtraction means for subtracting a subtraction value, obtained by the first subtraction means
First subtraction integrated value of the first subtraction integrated value and the first reference value and <br/> comparison of a predetermined time function outputs a <br/> start signal when the above first reference value was First comparing means and the peak cut
A second product fraction means for integrating the previous acceleration waveform time, the second
Comparing the second time integrated value obtained by the integrating means with a predetermined second reference value, and comparing the second time integrated value with the second reference value;
A second comparing means for outputting a start signal to, the AND for outputting a start signal to the trigger circuit when both are entered with a start signal from the start signal and the second comparison means from said first comparing means is made of comprises a means.

Further , as a modified example of the above method, the second method
In the comparing means, the second time integral value and the second reference
Instead of comparing with the second time integral value,
Second subtraction integral obtained by second subtraction means for subtracting the subtraction value
Comparing the value with the second reference value and determining the second time integral value with the second reference value.
In the case of 2 or more reference values, the starting signal is sent from the second comparing means.
Some are designed to output. Further, the first subtraction
The integrated value change amount per predetermined time of the integrated value is calculated, and
The integrating and the product fraction value variation by comparing the predetermined change amount reference value
Outputs a start signal when the value change is equal to or greater than the change reference value.
A third comparing means for performing the operation, and the third comparing means and the first comparing means.
A start signal is issued from one or both of the comparison means.
Is sent to the AND means.
There are things. Also, the first comparing means and / or the third ratio
Holding the start signal output from the comparison means
Means, and the holding signal from the starting signal holding means is
Input to the AND means, and in this state,
Is input to the AND means, the trigger
-A start signal can be output to the circuit.
You.

[0010]

SUMMARY OF] In the first comparison means, the normal high-speed oblique collision or pole collision is start conditions are classified as low-speed frontal collision is no fire condition performs starting and no fire decision. In the second comparison means to determine whether the rate change by comparing the time integral value of the acceleration waveform without a peak cut with a predetermined second reference value. As a result , the vibration component due to the bottoming of the body or the like on a severe rough road hardly causes a speed change, so that it can be classified as a collision. Therefore, by performing an AND operation between the second comparing means and the first comparing means, it is possible to prevent a malfunction on a severe rough road.

[0011] Also, the second comparing means, the speed change, so therefore can determine the magnitude of the collision energy, used as a means for setting timing (the timing) which emits a starting signal, the output side of the first comparison means If the start signal holding means is provided between the AND circuit and the AND means, the start signal of the first comparing means can be output to the trigger circuit of the airbag at a predetermined time.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. Here , the acceleration on the deceleration side will be described as a positive value, but making it negative will have the same effect if the positive and negative logics in each block are matched. FIG.
FIG. 2 is a block diagram of the collision sensor of the present invention, FIG. 2 is an acceleration diagram showing calculation processing of the collision sensor of FIG. 1, FIG. 3 is a graph showing a change in the first subtraction integral value of the collision sensor of the present invention, and FIG.
FIG. 5 is a graph showing a change in the second subtraction integral value of the collision sensor of the present invention, FIG. 5 is a block diagram of a second embodiment of the collision sensor of the present invention, and FIGS. 6 and 7 are arithmetic processing of the collision sensor of FIG. FIG. 7 is a graph showing a change in an integral value indicating the following.

In FIG. 1, an accelerometer 1 includes an arithmetic circuit 3
Through the reset circuit 4 and the trigger circuit 5. Then, the trigger circuit 5 starts the airbag 6 as the occupant protection device. The following describes the calculation circuit 3. In block 11, a time point t0 at which the acceleration G measured by the accelerometer 1 exceeds the predetermined acceleration G1 is determined.
In block 12, from this time point t0, an acceleration G3 equal to or higher than the predetermined acceleration G2 is calculated (the acceleration G2 or lower is regarded as zero). In block 13, which is the first integration means, time integration of the acceleration G3 is started, and a first time integration value V is calculated. In a block 14 which is a first subtraction means, a first subtraction value ΔV which is a time integral value of a predetermined function is subtracted from the first time integral value V. Block 1 shown
In 4, the first subtraction value ΔV is a constant value, the first subtraction integrated value by subtracting a predetermined value ΔV per unit time V1
Is calculated . The first subtraction integral value V1 is output to the block 16 a block 15 and the third comparing means is a first comparing means. Then, the result of the blocks 15 and 16 is passed to the AND circuit 36 via the block 17 as the connection means.
Is output to

In a block 15 which is a first comparing means, a predetermined first reference value V2 (block 22) which changes with time in a block 21 is compared with the first subtraction integral value V1. In line 23, V1 is V2
When (V1 ≧ V2) , the block 1 serving as the connection means
7, a start signal is output. On the other hand, V 1 does not lead to V2
In the case (V1 <V2), the signal is blocked from the line 24.
Outputs to the lock 18, stops for the time integration issues a signal to the reset circuit 4 detects that V1 in the block 18 is near zero (negative or slight positive value), V, V1,
V5, V6 and t are each reset to zero. The first comparison means is that by detecting the normal high speed oblique collision or pole collision while dividing the low speed head-on collision, emits a start signal to the timing start request.

In a block 16 which is a third comparing means, a change amount (ΔV1) of the first subtraction integral value per a predetermined time is calculated in a block 25. Then, the change amount reference value ΔV4 (block 2
7) is compared with the change amount ΔV1 . Δ V1 is ΔV4
When (ΔV1 ≧ ΔV4) as described above, a start signal is output from the line 28 to the block 17 as the connection means. On the other hand ,
When ΔV1 does not reach ΔV4 (ΔV1 <ΔV4)
Outputs its signal from line 29 to block 18,
When the block 18 detects that V1 is close to zero (negative or slightly positive value), it issues a signal to the reset circuit 4 to stop time integration, and resets V, V1 , V5, V6 , and t.
Reset each to zero. The third comparison means, if the sufficient acceleration until start request timing is not transmitted to the chamber by a vehicle body characteristics and collision type and the like, are those used in place of the first comparison means, abrupt first subtraction integral value The start signal is issued by paying attention to the increase.

The block 17 as a connecting means changes the OR circuit, the AND circuit, the switching circuit or a combination thereof with the passage of time. In the case of an OR circuit, a start signal from one of blocks 15 and 16
It is output to the D circuit 36. In the case of an AND circuit, when a start signal is output from both the blocks 15 and 16, the start signal is output to the AND circuit 36. A switching circuit is connected to, for example, a speedometer. If the speed is equal to or higher than a predetermined speed, the block 15 is connected to the AND circuit 36.If the speed is lower than the predetermined speed, the block 16 is connected to the AND circuit 36.
Either may output a start signal to the AND circuit 36. Also , by changing the combination form of the blocks 15 and 16 with the passage of time, for example, the first half of the start request time is limited to only the block 15, and the latter half of the start request time is combined with an OR circuit of the blocks 15 and 16, You can also. These are appropriately determined according to the characteristics of the vehicle in which the collision sensor is incorporated or the manner of setting the unstart condition.

Meanwhile, at block 50, from the time t0 described above, the acceleration G5 removing a predetermined noise G4 from the acceleration G, Te block 31 smell a second integration means
Performs time between integration, calculates a second time integral value V5. Second
In a block 32 which is a subtraction means, a second subtraction value ΔV2 which is an integral value of a predetermined function is calculated from the second time integral value V5.
Is subtracted. In the illustrated block 32, the case where the second subtraction value is a constant value ΔV2 is a predetermined value per unit time.
The second subtraction value ΔV2 is subtracted from the second time integral value .
2 subtraction integral value V6 is calculated ( however , ΔV2 << Δ
V). This second subtraction integral value V6 is output to the block 37 which is the second comparing means.

[0018] In block 37 a second comparator means, at block 33 is a comparator with a second reference value V 7 and before <br/> Symbol second subtraction integral value V6 predetermined block 3 5 < br /> Here, when V6 becomes V7 or more (V6 ≧ V7) , a start signal is output to the AND circuit 36 from the line 38 . On the other hand, V6 is not I Itaru to V7 (V6 <V7)
In that case, the signal is sent to the block 18 from the line 39.
Transmit, where V1 is near zero (negative or slightly positive)
Is detected, a signal is issued to the reset circuit 4 to stop the second time integration, and V, V1, V5, V
To reset the 6, t respectively to zero. The second comparing means focuses on the point that the vibration component due to the bottoming of the body hardly causes a speed change, and compares the second time integrated value based on the acceleration waveform without peak cut with a predetermined second reference value. By doing so, a start signal is issued in a normal high-speed diagonal collision, a pole collision, and a collision of a vehicle with low body rigidity, but the start signal is not issued depending on the vibration component.

Then, as described above, the blocks 15, 1
6 results, AN via block 17 is connected means
As well as being input to the D circuit 36, the result of the block 37 is also input to the AND circuit 36. The AND circuit 36 outputs a start signal to the trigger circuit 5 when both the signals from the blocks 17 and 37 are input. Thus, the first comparing means and the third comparing means distinguish the normal high-speed diagonal collision or the pole collision from the low-speed frontal collision while discriminating the collision in the case of a vehicle having a low body rigidity at an early stage. By the two comparing means, it is possible to prevent a malfunction on a severe rough road. Here, the AND circuit 36 may be any AND means, and is configured to output a start signal by judging using fuzzy inference or by weighting the signals from both the blocks 17 and 37. You can also.

[0020] Next, the operation processing block 11 to 14 described above will be described by the graph of FIG. In FIG. 2A, the calculation starts at time t0 when the acceleration G exceeds G1. A predetermined G2 below is regarded as zero, it is integrated over more time. Then, a predetermined first subtraction value ΔV is subtracted per unit time of the hatched portion. FIG.
In (b), the vertical line is time-integrated,
This is the first subtraction integral value V1. That is , the vertical line A is added as a negative value, but the portion B is cut . When the function of the reset circuit 4 is used, the start / reset of the integration can be performed without considering the start timing.

The first comparison circuit 15 and the third
The operation of the comparison circuit 16 and the connection means 17 (in the case of an OR circuit) will be described with reference to FIG. 3, which is a chart showing a change in the first subtraction integration value V1. As in the case of FIG. 8, with the integral time simply subtracting a constant acceleration from the acceleration G (V1 ') is a high speed oblique collision and a low speed head-on collision
Which was hardly able indicator, first subtraction integral value of 3
In V1, both are classified clearly. As line graph shown by a chain line, the first is a predetermined time function
By setting the reference value V2 in advance , a start signal is output from the first comparison circuit 15 to the connection means 17 of the OR circuit at the point A.
Is done . Therefore , it is possible to satisfy the inoperative state of the low-speed frontal collision and the starting of the high-speed oblique collision and the pole collision within the required start time. Further, in the case of a low car speed oblique collision or pole crash of the vehicle body rigidity, because V 1 in the second half of the request for starting time is increasing rapidly, the change amount ΔV1 unit time delta t skilled enough Change amount reference value ΔV4 or more (ΔV1 ≧ ΔV4)
Is detected at point B, so that the third comparison circuit 16 connects the OR circuit to the OR circuit within the start request time before V1 becomes equal to or more than the first reference value V2 (V1 ≧ V2) at point C. 17
Start signal will be output to. As a result , the airbag can be started at the start request time not only for a normal low-speed head-on collision or a pole collision, but also for a high-speed diagonal collision or a pole collision of a vehicle with low body rigidity.

Note that , in FIG.
The first subtraction value ΔV is converted to a function value, for example, the first time at that time.
It can be replaced with the value of the function of the inter- integral value V. On the other hand, in block 13 , only the simple time integration of the acceleration G3 is performed.
In other words , by integrating the acceleration G3 to the Kth power (K ≧ 1) with time, integrating the acceleration G3 to the nth order, and a combination thereof, the classification of a low-speed frontal collision, a high-speed oblique collision, and a collision of a soft vehicle body can be performed. It can be made clearer.
Further , the case where V1 of the block 18 becomes close to zero is defined as when V1 becomes equal to or less than a predetermined value V3 or when V1 becomes equal to or less than a value V4 which is a function of the acceleration G3 at that time. You can also. Further , before the block 11, a value Gx obtained by subtracting a value Gf obtained by filtering the acceleration G from the acceleration G with a time constant of 5 seconds or more is used in place of the acceleration G to eliminate the effect of zero drift of the accelerometer. Thereby, the calculation accuracy can be improved. Further , the mounting structure of the accelerometer 1 is vibrated at 50 to 2000 Hz (in terms of vibration characteristics in the traveling direction of the vehicle) to amplify the acceleration G or to amplify a specific frequency band in the electric circuit of the accelerometer 1. It can have a range.

[0023] Next, the operation processing block 31 described above will be described by the graph of FIG. 4 and FIG. 10. FIG.
At 0 (a), 40 is a vibration component due to rough road,
41 shows the waveform of the high-speed oblique collision, and 42 shows the waveform of the low-speed oblique collision. The vibration component 40 due to the rough road has a large amplitude on both the positive and negative sides of the acceleration. This is because with a deceleration if a collision, waveform 4 1, 4 as 2, but basically becomes the positive direction of the amplitude of one side, the vibration component due to rough road 4
0 is merely a vibration of the vehicle body caused by the bottoming of the body or the like, and hardly causes deceleration. Follow
In block 31, the normal time without peak cut
Interpolation is performed, and in block 32, the minute zero of the accelerometer is calculated.
Subtraction that eliminates drift is performed. In FIG.
The change of the second subtraction integral value V6 is, in the case of rough road ,
As shown by reference numeral 43 in the figure, the value changes at a low value near zero.
And high-speed oblique collisions and low speeds indicated by 44 and 45 in the figure.
It is clearly distinguished from a head-on collision . Therefore, as shown in the drawing, by setting the predetermined second reference value V7 appropriately in advance, it is possible to prevent malfunction due to severe rough road.

[0024] Incidentally, in FIG. 1, inserting a high-pass filter between the block 11 and the block 31, the vibration component due to rough road is because a high frequency, it becomes more clearly to distinguish the <br/> collide with rough road, effect Can be raised. Also , in FIG.
If a low-pass filter is inserted between the high- frequency component and the low-frequency component, the acceleration waveform that affects the speed change at the time of the collision has a low frequency.

[0025] Next, will be described on the basis of the second embodiment of the impact sensor of the present invention in FIGS. 5 to 7. 5 is different from FIG. 1 in that a block 51 as a starting signal holding unit from the block 17 is provided between the block 17 as a connecting unit of the first comparing unit and the third comparing unit and the AND circuit 86. That is, the block 51 is connected to the block 18. When receiving the start signal from the block 17, the block 51 sets the register IF to 1. AN
When the register IF is 1, the D circuit 86 outputs a start signal to the trigger circuit 5 when a start signal is input from the second comparing means. When the block 18 detects that V1 is near zero, a signal is issued to the reset circuit 4 to stop the time integration in the blocks 13 and 31, and the register IF of the block 51 is reset to 0. The second comparing means is set to output a start signal at a start request time. Here, since the second comparing means is watching the speed, the momentum which is the product of the speed and the mass , and hence the magnitude of the collision energy, the second comparing means appropriately determines the starting timing without being affected by the acceleration waveform. Can be set.

[0026] Next, the operation of the impact sensor of the present embodiment FIG. 6
And the graph of FIG. In FIG. 6, FIG.
When a collision wave having an undulation as shown in FIG. 1A is input, the first subtracted integral value V1 also becomes a wave having an undulation 82 as shown in FIG. Earlier, the first subtraction integral value V1
The first reference value 62 is reached ( reference numeral 65 ). Then, the first comparing means outputs a start signal, and the register IF is set to 1 as shown in FIG. Then, as shown in FIG. 6C, within the start request timing 84, the second subtraction integral value V6 reaches a predetermined second reference value 69 ( reference numeral 67).
And the second comparing means outputs a start signal.
A start signal is output from the ND circuit to start the airbag. In a low-speed head-on collision (dotted line), which is a non-start condition, a start signal is output from the second comparing means at the point 68 in FIG. 6C, but as shown in FIG. Since the start signal is not output from the first comparing means,
The start signal is not output from the D circuit, and the airbag does not start. Immediate Chi, since the starting and non-starting of the determination is performed in the first comparison means, second comparison means, the second reference value as a primary configuration suitable timing for starting the air bag 69
, It is possible to control the timing of starting the airbag. The setting of the timing for starting the air bag, and a second reference value 69 is performed by appropriately selecting the degree of subtraction in Bro <br/> click 3 2 of FIG. As a result of being able to control the start timing in this way, it is possible to prevent a start that is too early for the start request time and to reduce the variation in the start timing .

[0027] Further, in FIG. 7, as shown in FIG. 12 (a), when a collision wave first swell 84 is not so large is input, the first subtraction integral value V1 is shown in FIG. 7 (a) Thus, the waveform has a swell 85 before the start request time 84. Then, a predetermined first reference value 7 as shown in FIG.
By setting the 0, first comparing means at the time of the reference numeral 71 outputs a start signal, as in the case of the above mentioned, the register IF
There is set to 1, 7 as shown in (c), in the start request timing 84, the second second subtraction integrated value V6 is predetermined
The reference value 74 reaches Then (reference numeral 72), second comparison means 37
Outputs a start signal to the AND circuit.
Start signal is output to the trigger circuit airbag is started. Thus, as a result of being able to control the start timing ,
The airbag can be operated properly even for a collision wave in which the first undulation 84 is not so large. Also ,
Since the first comparison means is not restricted by the start time, the judgment of the start / non-start may be considered first, and the first comparison means of the time function may be used.
The degree of freedom for setting the quasi-value 70 is increased, and accordingly, the determination accuracy can be improved.

[0028] The first above, the third in the second embodiment
Although a comparison unit is added, the unit is an optional element, and the present invention can be realized without the unit.

[0029]

According to the collision sensor of the present invention, the high-speed oblique collision or the pole collision is classified into the low-speed frontal collision by the first comparing means, and the time integrated value of the acceleration waveform which is not peak-cut by the second comparing means is set to a predetermined value. It is determined whether there is a speed change by comparing with the second comparison means, and the AND operation of the second comparison means and the first comparison means is performed. By means of the means, the bottoming of the body, which is a vibration component that does not cause a speed change, can be classified as a collision, and a malfunction on a severe rough road can be prevented.

[0030] Further, a start signal holding means between the output side and the AND unit of the first comparison means is provided, the second comparison means, Ru is used as means for setting the timing for issuing a starting signal
Then , the start signal of the first comparing means can be output to the trigger circuit of the airbag at an appropriate timing to start the airbag, so that the start timing can be controlled. Therefore, it is possible to control the operation timing of the airbag, and it is possible to prevent early operation and non-operation of a wider range of collision waves, and to start the vehicle.
Timing variations can be reduced.
Further , since the first comparison means is not restricted by the start time, the degree of freedom of the start / non-start judgment is increased, and the judgment accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a collision sensor according to the present invention.

FIG. 2 is an acceleration diagram showing calculation processing of the collision sensor of FIG. 1;

3 is a graph showing temporal variations <br/> of first subtraction integrated value of the collision sensor of the present invention.

4 is a graph showing temporal variations <br/> of second subtraction integrated value of the collision sensor of the present invention.

FIG. 5 is a block diagram of a second embodiment of the collision sensor according to the present invention.

[6] After the integrated value indicating the arithmetic processing of the collision sensor of Fig. 5
Is a graph showing the time change.

[7] After the integrated value indicating the arithmetic processing of the collision sensor of Fig. 5
Is a graph showing the time change.

8 is a graph showing temporal changes in acceleration.

9 is a graph showing changes over time in the time integration value of a conventional crash sensor.

10 is a graph showing changes with time and changes over time in the time integration value of a conventional crash sensor of acceleration.

11 is a graph showing changes with time and changes over time in the time integration value of a conventional crash sensor of acceleration.

12 is a graph showing changes with time and changes over time in the time integration value of a conventional crash sensor of acceleration.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Accelerometer 4 Reset circuit 5 Trigger circuit 12 Peak cut means 13 1st integration means 14 1st subtraction means 15 1st comparison means 16 2nd comparison means 31 2nd integration means 32 2nd subtraction means 36 AND circuit (AND means) 37 Second comparing means 51 Starting signal holding means 86 AND circuit (AND means)

Continuation of front page (56) References JP-A-4-321455 (JP, A) JP-A-4-287748 (JP, A)

Claims (5)

(57) [Claims] 1. A collision sensor for detecting a vehicle collision from an acceleration waveform (G ) of an accelerometer (1) and starting an occupant protection device such as an airbag (6) by a trigger circuit (5). A peak cut means (12 ) for performing a peak cut of a predetermined value (G2) or less on the waveform (G), and a first integrating means for time-integrating the peak cut waveform (G3) obtained by the peak cut means (12) (13) and subtracting a first subtraction value (ΔV) of a predetermined function from the first time integration value (V) obtained by the first integration means (13).
A first subtraction means (14); and a first subtraction integrated value (V ) obtained by the first subtraction means (14).
1) is compared with a first reference value (V2) of a predetermined time function .
When the first subtraction integral value is equal to or greater than the first reference value (V1 ≧ V2)
A first comparison means for outputting a start signal (15) when said peak-cut before the acceleration waveform second integrals means for integrating the (G) time (31), obtained in said second integrating means (31) second time integral value which is (V
5) is compared with a predetermined second reference value (V7) and the second time
Integrated value second reference value or more (V5 ≧ V7) of the second comparator means for outputting a start signal (37) when the starting signal from the first comparator means (15) and said second comparing means ( both have been input field of the starting signal from 37)
Which outputs a start signal to the trigger circuit (5)
Crash sensor characterized in that it comprises a D unit (36), the. 2. The method according to claim 1, wherein said second comparing means (37) comprises :
The second time integral value (V5) and the second reference value (V7)
Is replaced by a predetermined second subtraction from the second time integrated value.
Value obtained by the second subtraction means (32) for subtracting the value (ΔV2).
The second subtracted integral value (V6) is referred to as the second reference value (V7).
By comparison, the second subtraction integral value is equal to or greater than the second reference value (V6 ≧
V7), the starting signal is sent from the second comparing means (37).
2. The collision sensor according to claim 1, wherein the collision sensor outputs a signal. 3. A predetermined time period for the first subtraction integral value (V1)
Is calculated (ΔV1), and the integrated value change amount is calculated.
The amount of conversion is compared with a predetermined change amount reference value (ΔV4),
When the value change amount is equal to or greater than the change amount reference value (ΔV1 ≧ ΔV4)
A third comparing means (16) for outputting a start signal when the third comparing means (16) and the first comparing means (15) are provided .
When a start signal is output from one or both of
Then, this is transmitted to the AND means (36).
Crash sensor according to claim 1 or 2 comprising Te. 4. An output from said first comparing means (15).
Start signal holding means (51) for holding a start signal
The holding signal from the starting signal holding means (51) is
The signal is input to AND means (86), and in this state, the second comparison
The starting signal from the means (37) is supplied to the AND means (86).
When input, a start signal is output to the trigger circuit (5).
The collision sensor according to claim 1, wherein the collision sensor is configured to be forced. 5. The first comparing means (15) or the third comparing means (15).
A start signal holding circuit for holding a start signal from the comparing means (16).
Holding means (51), and the starting signal holding means (51)
These holding signals are input to the AND means (86),
In the state, the start signal from the second comparing means (37) is A
When input to the ND means (86), the trigger circuit
(5) The starting signal is output in (5).
The collision sensor as described .