JP3444916B2 - Occupant protection start circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a starting circuit for an occupant protection device such as an air bag or a seat belt pretensioner which operates by detecting a collision of a vehicle.

[0002]

2. Description of the Related Art FIG. 11 shows a starting circuit of a conventional occupant protection device disclosed in Japanese Utility Model Laid-Open No. 2-5371.
In FIG. 11, 3 is a means for starting an occupant protection device called a squib, 4 is a DC power source such as an on-vehicle battery, 11
Is an acceleration sensor for converting acceleration in the deceleration direction of the vehicle (hereinafter referred to as deceleration) into an electric signal, 12 is an amplifier, 13 is an A / D converter, 14 is a microcomputer, 16 and 3
4 is a transistor, 15 and 33 are transistors 16 and 3
Reference numeral 4 is a resistor for limiting the base current, 30 is an integrator, 31 is a comparator, 32 is a one-shot circuit, and 17 is a mechanical contact type impact sensor.

Next, the operation will be described. When the vehicle collides, the acceleration sensor 11 converts the deceleration of the vehicle into an electric signal, and the amplifier 12 amplifies the electric signal. The amplified deceleration signal is time-integrated by the integrator 30 and becomes the vehicle speed change amount. When the speed change amount becomes larger than the reference value Vr, the output of the comparator 31 becomes the “H” level,
Transistor 3 for a certain period of time via one-shot circuit 32
Turn on 4.

On the other hand, the deceleration signal is also input to the microcomputer 14 via the A / D converter 13. The microcomputer 14 performs the same process as that performed by the integrator 30, the comparator 31, and the one-shot circuit 32, and turns on the transistor 16 for a certain period of time. Further, the impact sensor 17 is set to be turned on even with a relatively light impact.

Therefore, in a collision of a certain level or more of shock, the transistor 16, the transistor 34 and the shock sensor 17 are simultaneously turned on, the squib 3 is supplied with current from the DC power source 4, and an occupant protection device (not shown) is activated. To do.

[0006]

Since the starting circuit of the conventional occupant protection system is constructed as described above, the collision of the vehicle is judged by the integrated value of the deceleration signal. Considering the deceleration waveform after the collision as shown in FIG.
2 (a) is the case of a head-on collision of 8 mph, and the occupant protection device should not be operated. Therefore, the reference value Vr of the comparator 31 is set to a value larger than the integral value ΔVA1 of the deceleration signal GA over the entire time region.

On the other hand, FIG. 12B shows a case of an underride collision of 20 mph at time tF.
It is necessary to determine by the time 2 that the collision should operate the occupant protection device. However, the deceleration signal GA until time tF2
The integrated value ΔVA2 of Δ is
Smaller than VA1 and therefore the reference value V of the comparator 31
Since it is smaller than r, it cannot be determined that the collision is due to activate the occupant protection device by the time tF2.

As described above, the conventional occupant protection device starting circuit has a problem that the occupant protection device cannot be operated within a necessary time in a special collision mode such as underride.

The invention of claim 1 has been made to solve the above-mentioned problems. Even in a special collision mode such as underride, the occupant can be distinguished from the collision during low speed running within a necessary time. An object of the present invention is to obtain a starting circuit of an occupant protection device that can operate the protection device.

According to the second aspect of the present invention, there is provided a starting circuit for an occupant protection device capable of accurately determining whether or not the occupant protection device should be operated even if the wheels are locked by sudden braking immediately before the collision. The purpose is to get.

[0011]

A starting circuit of an occupant protection system according to the invention of claim 1 is an electric signal from an acceleration sensor.
Is calculated to calculate the amount of speed change after a vehicle collision.
To, the speed from a vehicle speed just before collision resulting from the vehicle speed sensor
The speed value is calculated by subtracting the amount of change in
By comparison with, but which is adapted to determine whether to operate the occupant protection device.

The starting circuit of the occupant protection system according to the invention of claim 2 is obtained from the vehicle speed sensor by the previous vehicle speed detection process.
Based on the previous vehicle speed and the current vehicle speed detection process
When it is determined that the wheels are in the locked state by comparing the amount of change with the current vehicle speed obtained from the above and the amount of speed change, the value obtained by subtracting the above amount of speed change from the previous vehicle speed is used as the above vehicle speed. It is a thing.

[0013]

In the occupant protection system according to the first aspect of the present invention, since the vehicle speed immediately before the collision is low even in the case of a head-on collision in a collision caused by a low speed running, the electric circuit from the acceleration sensor is used.
When the signal is integrated to calculate the amount of speed change after a vehicle collision,
Both are above the vehicle speed immediately before the collision obtained from the vehicle speed sensor.
The speed value is calculated by subtracting the speed change amount, and the speed value above is calculated.
By judging whether or not the operation of the occupant protection device is necessary by comparing with a fixed value, it is possible to distinguish between a frontal collision during low speed traveling and a special collision such as underride, and a passenger protection device for a frontal collision during low speed traveling. In the case of a special collision such as underride, the occupant protection device is operated within an appropriate time.

The starting circuit of the occupant protection system according to the invention of claim 2 is obtained from the vehicle speed sensor by the previous vehicle speed detection processing.
Based on the previous vehicle speed and the current vehicle speed detection process
When comparing the amount of change from the vehicle speed obtained this time with the amount of speed change and determining that the wheels are locked, the value obtained by subtracting the amount of speed change from the previous vehicle speed is used as the vehicle speed. Since the wheel is locked due to sudden braking immediately before the collision and the vehicle speed detected by the vehicle speed sensor becomes zero, whether or not the occupant protection device should be operated using the accurate vehicle speed immediately before the collision. It will be possible to make accurate decisions.

[0015]

EXAMPLES Example 1. An embodiment of the invention of claim 1 will be described below with reference to the drawings. FIG. 1 is a circuit block diagram showing a starting circuit of an occupant protection system according to this embodiment. In FIG. 1, 1 is a starting circuit of the occupant protection system and 2 is a vehicle speed for outputting a pulse train having an interval inversely proportional to the speed of the vehicle. It is a sensor. Reference numeral 3 is an occupant protection device starting means called a squib (starting means), and 4 is a DC power source (power source) such as a vehicle battery. In the starting circuit 1, 11 is an acceleration sensor for converting the deceleration of the vehicle into an electric signal, 12 is an amplifier, 13 is an A / D converter, 14 is a microcomputer (signal processing means, failure diagnosis means), and 16 is A transistor (switching means), 15 is a resistor for limiting the base current of the transistor 16, and 17 is a mechanical contact type impact sensor.

[0016] Next, the operation will be described. 2 and 3
3 is a flowchart showing the operation of this embodiment. The processing in the microcomputer 14 includes processing v repeated at a cycle of about 5 msec as shown in FIG. 2 and processing g repeated at a cycle of about 500 μsec as shown in FIG. Shall be processed in parallel in a time division manner. In process v, the time interval T of the pulse train from the vehicle speed sensor 2 is measured in step ST101, and in step ST102, the vehicle speed V1 is obtained by multiplying the reciprocal of the pulse train time interval T by a coefficient K.

In step g, the deceleration signal GA output from the A / D converter 13 is fetched in step ST201, and it is further determined in step ST202 whether or not the deceleration signal GA exceeds a relatively low threshold Th1. , Threshold T
If h1 is not exceeded, the deceleration signal G in step ST203
The speed variation ΔVA obtained by numerically integrating A is cleared and the process proceeds to step ST208.

Meanwhile, if the deceleration signal GA is judged it exceeds the threshold value Th1 in step ST 202, determines that a collision has started, the processing in step ST 204 v, i.e. stops the detection of the vehicle speed V1, only the processing g From this point Then, in step ST205, the deceleration signal GA is numerically integrated to obtain ΔVA.

[0019] Then, if ΔVA in step ST206 is exceeds the threshold value Th2, the process proceeds to step ST207, a value obtained by subtracting the speed variation ΔVA from the vehicle speed V1 is the threshold Th3
Is exceeded, and if the threshold value Th3 is exceeded, it is determined that the collision is one in which the occupant protection device should be operated, and step ST2 is performed.
Go to 09.

In step ST209, the output signal S is set to the "L" level and the transistor 16 is turned on for a certain period of time. At this time, since the impact sensor 17 is turned on at the same time, a current is supplied to the squib 3 from the DC power source 4, and an occupant protection device (not shown) is activated.

Further , step ST206 and step ST
When the thresholds Th2 and Th3 are not exceeded in 207, the process proceeds to step ST208 and the output signal S is set to "H".
The transistor 16 is set to the level, and the transistor 16 remains off.

FIG . 4A shows a deceleration waveform of a front collision of 8 mph, and FIG. 4B shows a deceleration waveform of a collision of 20 mph underride. The maximum deceleration is several tens of G. . FIG. 4C shows an integrated waveform of the deceleration of FIGS. 4A and 4B. In the waveform shown in (c) of FIG.
The times at which the speed change amount ΔVA exceeds the threshold Th2 in step ST206 of FIG. 3 are defined as tF1 and tF2, respectively. Here, tF2 is the time at which it must be determined by this time that there is a collision in which the occupant protection device should be operated.

[0023] Then, step ST2 of this immediately, and FIG. 3
In step 07, V1-ΔVA is compared with the threshold Th3. Here, V1 is the vehicle speed immediately before the collision, and is equal to the integral value of the entire deceleration waveform in the deceleration direction until the vehicle speed becomes zero at the time of the collision. In FIG. 4A, V1a and in FIG. V1
It is represented by b. Therefore, V1-ΔVA is the time tF1,
It becomes the integrated value of the deceleration waveform after tF2, and as shown in (a) and (b) of FIG. 4, A = V1 in the case of (a).
In the case of a-ΔVA, (b), B = V1b-ΔVA. Then, as is clear from FIG. 4C, B is A
It is about 2.5 times larger than

[0024] Therefore, the threshold Th3 in step ST207 in FIG. 3 by setting between A and B, A <Th3 becomes a 8mph frontal collision of FIG. 4 (a), in the entire region of the deceleration waveform The process proceeds to step ST208 in FIG. 3, and the occupant protection device is not operated,
Further, in the 20 mph underride collision of FIG. 4B, B> Th3, so at time tF2, the process proceeds from step ST207 to step ST209 of FIG. Operate the passenger protection device.

[0025] Example 2. An embodiment of the invention of claim 2 will be described below with reference to the drawings. FIG. 5 is a circuit block diagram showing a starting circuit of the occupant protection system of this embodiment. 5, parts that are the same as or equivalent to those in FIG. In the figure, reference numeral 18 is an amplifier, and its amplification degree is set to be considerably larger than that of the amplifier 12. 19 is A /
It is a D converter.

Next will be explained with reference to flowcharts of FIGS. 6 and 7 The operation of this embodiment. 6 and 7, parts that are the same as or correspond to those in FIGS. 2 and 3 are assigned the same reference numerals and explanations thereof are omitted. In step ST211 of the process g, the deceleration signal GB output from the A / D converter 19 is fetched. In this case, consider the value of acceleration of about 1 G or less that occurs during normal traveling as the magnitude of the deceleration signal GB. When the operation proceeds to step ST212, the deceleration signal GB is numerically integrated to obtain the speed change amount ΔVB. On the other hand, in the process v, the current vehicle speed V2 is calculated and stored in step ST105. In step ST106, the value obtained by subtracting the vehicle speed V2 of this time from the vehicle speed V1 obtained by the previous calculation, that is, the vehicle speed change amount (V1
-V2) is the speed change amount ΔVB calculated in the process g.
It is checked whether or not it is within a certain range ΔVB ± α centered at, and if it is within that range, the process proceeds to step ST107, the vehicle speed V1 is updated, and further the process proceeds to step ST108 where the speed change amount is set to zero and Match the vehicle speed change amount and the speed change amount measurement period.

[0027] When the vehicle speed change in step ST106 is judged to be outside the range, the process proceeds to step ST109 without updating the vehicle speed V1. Step ST
By 109, the wheels were locked due to sudden braking
When the determination is made , the ΔVB is subtracted from the vehicle speed V1 and the V1 is updated. When the wheels are unlocked, the vehicle speed V2 becomes a normal value. Therefore, in the unlocked state, step ST106 is followed by step ST10.
The process 7 is executed, and the process returns to the normal process.
As a result, even if the wheels are locked by the sudden braking immediately before the collision, the vehicle speed immediately before that is stored, and the vehicle speed detected by the vehicle speed sensor 2 does not become zero. Step ST207 of processing g of vehicle speed
It can be used to make a collision judgment accurately even when the wheels are locked.

[0028] Example 3. An embodiment of the invention of claim 3 will be described below with reference to the drawings. FIG. 8 is a circuit block diagram showing a starting circuit of the occupant protection system of this embodiment. 8, parts that are the same as or correspond to those in FIG. 5 are assigned the same reference numerals and explanations thereof will be omitted. In FIG. 8, 5 is an alarm lamp for notifying the driver of an abnormality, 21 is a transistor (switching means) controlled by the microcomputer 14 via the resistor 20, the alarm lamp 5 and the transistor 2
1 is connected in series with the DC power supply 4. Reference numeral 22 is a forced drive means (fault diagnosis means) for the acceleration sensor 11.

A description will now be given with reference to the flowchart of FIG. 9 and FIG. 10, the operation. Also in this embodiment, the second embodiment
Similarly, there are processes v and g, and they are processed in parallel in a time-division manner. Since the process g is the same as that in FIG. 7, its illustration and description are omitted. Further, a process g ′ shown in FIG. 9 is newly provided. The process g'will be described. This process g'is performed immediately after the power supply of the starting circuit 1 of the occupant protection device is turned on. In step ST301, the signal S3 of the'H 'level is output to the forcible drive means 22 and the forcible drive is performed. The means 22 is operated to forcibly drive the acceleration sensor 11. Then, the output of the acceleration sensor 11 is A / D
It is converted and captured in step ST302.

Furthermore, the acceleration sensor 11 is A / D converted
It is checked in step ST303 whether or not the output is a correct value, and if abnormal, the process proceeds to step ST304, the signal S2 is set to the “L” level, the alarm lamp 5 is turned on to notify the driver of the occurrence of the failure, and the step ST3
Proceeding to 05, the normal processing g and v shown in FIGS.
Do not work.

[0031] If it is determined to be normal in step ST 303, the process proceeds to step ST 306, turns off the alarm lamp 5 by the signal S2 to the 'H' level.

[0032] wheel in the sudden braking at the time of normal running will be described when it is locked. Regarding the process v, the same or corresponding portions as those in FIG. When the wheels are locked by the sudden braking immediately before the collision, the vehicle speed V2 becomes zero and ΔVB obtained in the process g also becomes close to zero. Therefore, step ST110 is executed after step ST106. Since ΔVB becomes smaller than the set value β in step ST110, step ST10
Proceed to 9. In step ST109, the vehicle speed V1 is updated by reducing ΔVB as in the second embodiment.

Further, the acceleration sensor 11 immediately after the power-on of the starting circuit of the occupant protection device is the failure diagnosis process g ',
When it is determined that the acceleration sensor 11 is normal, the process g and the process v are executed. Then, when the vehicle speed sensor is normal, the condition of step ST106 of the process v is satisfied, and therefore step ST114 is executed next.
In step ST114, the failure detection counter CT is reset to zero, the alarm lamp 5 is turned off in step ST115, and the vehicle speed V1 is updated in step ST17. If the vehicle speed sensor is abnormal, step ST
Since the condition of 106 is not satisfied, step ST step ST110 is executed next, and when the vehicle speed changes to some extent, the vehicle speed change amount ΔVB is larger than the set value β, so the process proceeds to step ST111.

In step ST111, the failure detection counter is incremented, and when the predetermined count number A or more is reached in step ST112, the process proceeds to step ST113. In step ST113, the alarm lamp 5 is turned on to notify the driver of the occurrence of the vehicle speed sensor failure.
Even if the vehicle speed sensor is in the normal state and the wheel lock is followed by step ST110 and then step ST111, setting the count A of the failure detection counter to a sufficiently large value prevents the vehicle speed from proceeding to step ST113. It is not determined that the sensor is abnormal, and step ST10
At 9 the vehicle speed V1 is updated. Since the vehicle speed V2 becomes a normal value after the wheels are unlocked, step ST10
In step 6, the process proceeds to step ST114 and returns to the normal process.

[0035] Example 4. In addition, the above-described first to first embodiments
In the third embodiment, there may be a plurality of squibs serving as the starting means and a circuit for igniting the squibs, and the switching means composed of transistors may be switching elements other than transistors.
Further, the microcomputer and the A / D converter may be a logic circuit configured by combining logic elements or the like as long as they have the same function.

[0036]

According to the invention of claim 1, the acceleration sensor
By integrating the electrical signal from the
Along with the calculation, a speed value obtained by subtracting the above speed change amount from the vehicle speed immediately before the collision obtained from the vehicle speed sensor is calculated,
Since it is configured to determine whether or not the operation of the occupant protection device is necessary by comparing the speed value with a predetermined value, whether or not the occupant protection device should be operated is determined in a special collision mode such as underride. Even when the vehicle is traveling at a low speed, it is possible to make a distinction within a necessary time by distinguishing it from a frontal collision, and it is possible to obtain a starting circuit for an occupant protection device that has a fast response and high reliability.

According to the invention of claim 2, the previous vehicle speed detection
The previous vehicle speed obtained from the vehicle speed sensor and the current
By comparing the amount of change with the current vehicle speed obtained from the vehicle speed sensor by the vehicle speed detection process and the amount of speed change, when it is determined that the wheels are locked, the above amount of speed change is subtracted from the previous vehicle speed. By using the value as the vehicle speed, it is configured to determine whether to operate the occupant protection device,
In the event of a collision, the wheels will lock due to sudden braking,
Even if the vehicle speed detected by the vehicle speed sensor becomes zero, it is possible to reliably determine within a required time whether or not a collision should operate the occupant protection device, and a responsive occupant protection device start circuit with high response and reliability can be obtained. It is effective.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing a starting circuit of an occupant protection system according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a process v of a starting circuit of an occupant protection system according to an embodiment of the present invention.

FIG. 3 is a flowchart showing a process g of a starting circuit of an occupant protection system according to an embodiment of the present invention.

FIG. 4 is a waveform diagram showing output waveforms of the acceleration sensor at the time of a 8 mph frontal collision and a 20 mph underride.

FIG. 5 is a circuit block diagram showing a starting circuit of an occupant protection system according to an embodiment of the present invention.

FIG. 6 is a flowchart showing a process v of a starting circuit of an occupant protection system according to an embodiment of the present invention.

FIG. 7 is a flowchart showing a process g of a starting circuit of an occupant protection system according to an embodiment of the present invention.

FIG. 8 is a circuit block diagram showing a starting circuit of an occupant protection system according to an embodiment of the invention of claim 3;

FIG. 9 is a flowchart showing a process g ′ of a starting circuit of an occupant protection system according to an embodiment of the invention of claim 3;

FIG. 10 is a flowchart showing a process v of a starting circuit of an occupant protection system according to an embodiment of the present invention.

FIG. 11 is a circuit block diagram showing a starting circuit of a conventional passenger protection device.

FIG. 12 is a waveform diagram showing output waveforms of the acceleration sensor at the time of a 8 mph frontal collision and a 20 mph underride.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Start circuit of occupant protection device 2 Vehicle speed sensor 3 Squib (starting means) 4 DC power supply (power supply) 11 Acceleration sensor 14 Microcomputer (signal processing means, failure diagnosis means) 16 Transistor (switching means) 22 Forced drive means (fault diagnosis) means)

Claims (2)

(57) [Claims] 1. A starting means for operating an occupant protection device by supplying a current greater than a predetermined value, a power supply for supplying a current to the starting means, and a series connection between the starting means and the power supply. In the starting circuit of the occupant protection device, the switching circuit, an acceleration sensor for detecting the acceleration in the deceleration direction of the vehicle, a vehicle speed sensor for detecting the speed of the vehicle, and a signal processing means for controlling the switching means are provided. The processing means calculates the speed change amount after the collision of the vehicle by integrating the electric signal from the acceleration sensor, and calculates the speed value obtained by subtracting the speed change amount from the vehicle speed immediately before the collision obtained from the vehicle speed sensor. Then, by comparing the speed value with a predetermined value, it is determined whether or not to operate the occupant protection device. 2. A vehicle speed sensor based on the previous vehicle speed detection processing
The vehicle speed obtained from the previous vehicle speed and the vehicle speed detection processing this time
When comparing the amount of change from the vehicle speed and the amount of speed change obtained from the sensor this time, and when it is determined that the wheels are locked, the value obtained by subtracting the amount of speed change from the previous vehicle speed is used as the vehicle speed. The starting circuit for an occupant protection device according to claim 1, which is used.