JPH0961446A - Impact sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the contact failure of the contact part of a reed switch and to obtain a reliable impact sensor by dividing the corresponding contact part of the reed switch into a plurality of parts. SOLUTION: In a reed switch 1 used for an impact sensor, corresponding contacts 1a and 1b are divided into a plurality of pairs. That is, leads 11 and 12 of a magnetic body are sealed at both edges of a glass tube 3 so that the parts of the contacts 1a and 1b approach. When the line of magnetic force passes in the longitudinal direction of the leads 11 and 12, contacts 1a and 1b close due to magnetic induction. With the configuration of the reed switch 1, even if, for example, a foreign object blocks one contact 1a of, for example, the contact parts 1a and 1b to cause contact failure, the other contact 1b normally contacts and maintains continuity, thus improving reliability as a safing sensor. Also, the contacts 1a and 1b are divided into two portions in a glass tube 13 and the reed switch 1 is withdrawn externally in a similar manner as before, thus preventing cost from increasing nearly at all.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impact sensor provided with a reed switch whose contacts are closed by an impact, and more particularly to an impact sensor structure having improved reliability of an ignition circuit of an airbag.

[0002]

2. Description of the Related Art FIGS. 7A and 7B are views showing the structure of a reed switch used in a conventional impact sensor (for example, a safing sensor), where (a) is an upper sectional view, (b) is a side sectional view, and (c).
FIG. 6 is a sectional view taken along line D-D. 8A and 8B are diagrams illustrating a method of connecting terminals of a reed switch used in a conventional safing sensor, FIG. 8A is a perspective view, and FIG. 8B is a diagram showing a relationship between terminals and welding points. FIG. 9 is a sectional view showing the structure of a conventional safing sensor. FIG. 10 is a diagram illustrating a conventional airbag starting circuit. Hereinafter, description will be given with reference to the drawings.

An airbag is mounted as a safety device in the event of a vehicle collision, but conventionally, a plurality of collision detection sensors having different detection sensitivities, such as leads, have been used as an airbag starter device in order to prevent malfunction. A safing sensor consisting of a switch and a permanent magnet, which detects the collision by the movement of the permanent magnet caused by the acceleration at the time of collision, and a microcomputer based on the output of the G sensor, determines the collision, and ignites the airbag by the logical product. Methods have been taken to close the circuit and activate the airbag.

First, the reed switch 5 used in the safing sensor SS5 will be described. Magnetic leads 51 and 52 are sealed at both ends of the glass tube 53 so that the contact points 5a are closely opposed to each other. When the magnetic lines of force pass in the length direction of the leads 51, 52, the contact 5 is generated by magnetic induction.
a is closed (see FIG. 7). Next, the safing sensor S
The structure of S5 will be described. The reed switch 5 and the doughnut-shaped permanent magnet 8 are formed. The inertial force of the collision causes the permanent magnet 8 to overcome the pressure of the spring 7 and approaches the contact 5a of the reed switch 5 to close the contact 5a. Reference numeral 6 is an envelope. In addition to the airbag ignition terminals T51 and T54, the safing sensor SS5 includes a test terminal (a resistor R1).
T52 and T53 are provided (see FIG. 9).

The leads 51 and 52 of the reed switch 5 are made of a magnetic material and are sealed in a glass tube 53. These lead wires 51, 52 have four non-magnetic terminal wires 511, 5
Terminals T51 to T54 are taken out by 12, 521, 522 and one non-magnetic connecting line 54. In addition, connection of each material is performed by spot welding, and welding points A51 to
There are 5 points of A55. After they are assembled, they are sealed in the container. Further, the abnormality detection resistor R1 is connected between the terminals T52 and T53 (see FIG. 8).

Next, an airbag starting circuit will be described. E1 is an airbag ignition power supply unit, which is a battery B1.
And a backup capacitor C1.
SS5 is a safing sensor that detects a collision and closes the contact 5a of the reed switch 5. SC is an ignition element,
When energized, it ignites and causes chemical changes in the chemicals, generating gas and inflating the airbag. Tr
Reference numeral 1 denotes an ignition transistor, which is a microcomputer 92 that finally determines a collision based on a signal from a G sensor 91 (acceleration sensor).
The ignition signal from is supplied to the base and turned on. R1 is a resistance for detecting an abnormality in the ignition circuit, and the safing sensor SS5
Are connected in parallel.

In the event of a collision, first the safing sensor SS
5 detects a collision with low acceleration, and the contact 5a of the reed switch 5 closes. Next, the G sensor 91 detects a collision at a higher acceleration, and the microcomputer 92 makes a final judgment of a collision and outputs an ignition signal to turn on the ignition transistor Tr1. As a result, the power supply E1-the safing sensor S
S5-Ignition element SC-Ignition transistor Tr1-The loop of the whole circuit of ground is completed, current flows and ignition element S
C is ignited (see FIG. 10).

Since the airbag operates in an emergency, the contact 5a of the safing sensor SS5 does not close under normal conditions. Therefore, in order to monitor whether the ignition circuit unit is in a normally operable state for a long period of time, the ignition element SC is fired in parallel with the safing sensor SS5 which is in the open state (contact 5a is in the off state). An abnormality detecting resistor R1 for inserting a minute current that does not occur is inserted. Then, the microcomputer 92 outputs a test signal only for a short time, and the presence or absence of the disconnection fault is monitored by the current flowing through the resistor R1 for the disconnection of the ignition circuit.

[0009]

The safing sensor SS5 described above has a problem of low reliability as a whole. More specifically, the contact 5a of the reed switch 5
If foreign matter or the like is caught in the part and contact failure occurs at the contact 5a,
The switch may not turn on and the airbag may not deploy. As a countermeasure, there is a method in which two reed switches are connected in parallel and housed in one safing sensor to significantly reduce the probability of two reed switches causing contact failure at the same time. Become.

Further, since the contact 5a of the reed switch 5 is turned on and off by the magnetic field of the permanent magnet, the leads 51 and 52 constituting the contact 5a are magnetic bodies, and other wire members 511, 512 and 521 for connection. Non-magnetic materials are used for 522 and 54 so as not to disturb the magnetic field. Therefore, the two materials are connected at points A51 and A55 by spot welding or the like. Further, spot welding is similarly performed at the points A52 and A53 for connecting the abnormality detection resistor R1. If the welded part comes off, the airbag will not operate normally.
It is necessary to be able to check the welding location. However, in the conventional connection method, the terminal T51-the welding point A52
-Terminal T52-Resistance R1-Terminal T53-Welding point A53-
Since the continuity between the terminals T54 can be checked from the outside, the welding points A52 and A53 can be confirmed to be off, but the welding point A5
In Nos. 1, A54, and A55, the contact 5a of the reed switch 5 is in an open state, so that there is a problem that the deviation of the welding point cannot be checked.

Further, when the safing sensor SS5 is operating, that is, the period in which the contact 5a of the reed switch 5 is closed and the period in which the G sensor detects acceleration and the microcomputer issues an ignition signal overlap. Ignition element S for a certain period
An electric current flows through C. However, acceleration may temporarily change to positive (acceleration is negative because it is deceleration in a normal collision) due to deformation of the vehicle due to a collision. In such a case,
The period in which the contact 5a of the reed switch 5 is closed becomes short and the time required for the airbag to deploy is the ignition element SC.
There is a problem that current cannot be supplied to.

Further, since the safing sensor 5 is a mechanical switch and the contact 5a is housed in a hermetically sealed container, a pseudo signal or the like indicating whether or not the safing sensor 5 operates reliably until an actual collision occurs. Cannot be checked due to. Even if the reed switch is judged to be normal simply because it is in the open state, the reed 5 that constitutes the contact 5a is impacted by impact after the safing sensor SS5 is assembled.
When the Nos. 1 and 52 are deformed, there is a problem that the contact 5a is closed by a small impact or the contact 5a is not closed by a predetermined acceleration.

According to the present invention, the contact failure of the contact portion of the reed switch used for the impact sensor is eliminated, the welding point outside the reed switch can be checked, and the contact portion of the reed switch is closed. It is an object of the present invention to provide a highly reliable shock sensor by prolonging the time and enabling a test whether or not the contact portion is deformed.

[0014]

In order to achieve the above object, the present invention is a shock sensor comprising a reed switch, wherein a contact portion of the reed switch is closed by a shock to the reed switch, wherein the reed switch comprises: It is characterized in that the corresponding contact portions are divided into a plurality of pairs.

Further, in an impact sensor including a reed switch, in which a contact portion of the reed switch is closed by an impact on the reed switch, one end of an abnormality detection resistor is directly connected to one terminal of the reed switch, and the reed switch is connected. The other end of the abnormality detecting resistor is directly connected to the other terminal of the switch.

Further, in an impact sensor including a reed switch, wherein a contact portion of the reed switch is closed by an impact on the reed switch, the reed switch has an outer periphery of the reed switch corresponding to a contact portion of the reed switch. It is characterized in that it is connected in series to the coil wound around the portion. Further, in an impact sensor including a reed switch, in which a contact portion of the reed switch is closed by an impact on the reed switch, the reed switch includes a pair of leads for opening and closing the contact portion, and a reed switch which is always at a predetermined interval. It is characterized in that it is composed of a pair of guide members which are spaced apart from each other and come into contact with the leads in correspondence with each other.

[0017]

FIG. 1 is a diagram showing the structure of a reed switch used in a safing sensor according to a first embodiment of the present invention.
(A) is an upper sectional view, (b) is a side sectional view, and (c) is BB.
It is sectional drawing. Hereinafter, description will be given with reference to the drawings. The reed switch 1 used for the safing sensor will be described. Magnetic material leads 11 and 12 are sealed at both ends of the glass tube 13 so that the contact points 1a and 1b closely face each other. When the magnetic force lines pass in the length direction of the leads 11 and 12, the contact 1a is closed by magnetic induction.

In the structure of this reed switch 1, even if foreign matter or the like is caught in one of the contacts (for example, 1a) of the contacts 1a and 1b, a contact failure occurs, but the other contact (1b).
The normal contact and the continuity maintain the reliability of the safing sensor. Further, since the contacts 1a and 1b are divided into two inside the glass tube 13, and the reed switch 1 is pulled out to the outside in the same manner as in the conventional case, the assembly of the safing sensor may be different from the conventional case. There is almost no cost increase.

As described above, in the present embodiment, since the reed switch has two contacts inside, it is possible to remarkably reduce the operation abnormality due to contact failure or the like. 2A and 2B are views for explaining a terminal connection method of a reed switch used in a safing sensor according to a second embodiment of the present invention, FIG. 2A is a perspective view, and FIG. 2B is a view showing a relationship between terminals and welding points. Is. Hereinafter, description will be given with reference to the drawings.

First, the reed switch 2 used in the safing sensor will be described. The magnetic lead 2 is provided at both ends of the glass tube 23 so that the contact points 2a closely face each other.
1, 22 are sealed. When the magnetic lines of force pass in the length direction of the leads 21 and 22, the contact 2a is closed by magnetic induction. Next, a method of connecting the terminals of the reed switch 2 will be described. The leads 21 and 22 of the reed switch 2 are made of a magnetic material and are sealed in a glass tube 23. These lead wires 21 and 22 have four non-magnetic terminal wires 211 and 211.
Terminals T1 to T4 are taken out by 12, 221, 222 and one nonmagnetic connecting wire 24. In addition, connection of each material is performed by spot welding, and there are five welding points A1 to A5. After they are assembled, they are sealed in the container.

During the test, a continuity test is conducted between the terminals T1 and T4. In this case, terminal T1-welding point A1-welding point A2-terminal T2-abnormality detecting resistor R1-terminal T3-
Welding point A3-welding point A4-A continuity test of the loop of the terminal T4. Therefore, if there is a welding failure at any of the welding points A1 to A4, conduction can be lost between the terminals T1 and T4, and therefore it can be checked whether or not it is normal (however, since the contact 2a is in the open state, the welding point A5 is It cannot be tested even in this example).

As described above, according to the present embodiment, the continuity inspection can be performed at all the four welding points out of the five welding points necessary for pulling out the reed switch, and the reliability of the safing sensor is improved. FIG. 3 is a diagram illustrating a reed switch with a coil used in a safing sensor according to a third embodiment of the present invention. 4A and 4B are views for explaining a starting circuit of an airbag using a reed switch with a coil according to a third embodiment of the present invention. FIG. 4A shows a starting circuit diagram and FIG. 4B shows an operating time of a safing sensor. It is a figure. Hereinafter, description will be given with reference to the drawings.

First, the reed switch 3 used in the safing sensor will be described. The leads 3 made of a magnetic material are provided at both ends of the glass tube 33 so that the contact points 3a are closely opposed to each other.
1, 32 are sealed. When the magnetic force lines pass in the length direction of the leads 31 and 32, the contact 3a is closed by magnetic induction. The permanent magnet (not shown) overcomes the spring (not shown) pressure by the inertial force due to the collision, and the contact 3 of the reed switch 3
The contact 3a is closed as it approaches part a. Reference numeral 7 is a coil wound around the reed switch 3. One end 7a of the coil 7 is connected to the ignition power source and the other end 7b is connected to the lead 31 at the welding point 3A. After they are assembled, they are sealed in the container.

E1 is an air bag ignition power source section, which is composed of a battery B1 and a backup capacitor C1. R1 is a resistance for abnormality detection, and is connected in parallel to the power source E1 and the safing sensor SS3. SS3 is a safing sensor that detects a collision and closes the contact 3a. The safing sensor SS3 includes a reed switch 3 and a donut-shaped permanent magnet 8. The inertial force of the collision causes the permanent magnet 8 to spring (not shown).
The pressure is overcome, the contact 3a of the reed switch 3 is approached, and the contact 3a is closed. SC is an ignition element which, when energized, ignites to cause a chemical change in the chemical, generate gas, and inflate the airbag. Tr1 is an ignition transistor, and an ignition signal from a microcomputer 92 that finally determines a collision based on a signal from the G sensor 91 is supplied to the base to be turned on.

In the event of a collision, first the safing sensor SS
3 detects a collision with low acceleration, and the contact 3a of the switch closes. Next, the G sensor 91 (main acceleration sensor) detects a collision at a higher acceleration, and the microcomputer 92 makes a final determination of a collision, outputs an ignition signal, and turns on the ignition transistor Tr1. As a result, the power supply E1-safing sensor SS3-ignition element SC-ignition transistor T
The loop of the entire circuit of r1-ground is completed, a current flows, and the ignition element SC is ignited.

At this time, an ignition current flows through the reed switch 3 via the contact 3a. This current is reed switch 3
It also flows to the coil 7 connected in series via the lead 32 of the. As a result, the magnetic field due to the ignition current flowing through the coil 7 acts in the direction in which the contact 3a of the reed switch 3 is brought into contact. Therefore, the acceleration is temporarily reversed (or reduced) due to the deformation of the vehicle due to the collision, and the magnet 8 is moved to the contact 3a.
Even if the contact 3a tries to open away from the part, the coil 7
The safing sensor SS3 is maintained in the closed state continuously from the time when the contact 3a is first closed by the movement of the magnet 8 due to the magnetic field generated by the ignition current flowing in (FIG. 4 (b)).
reference). As a result, the time during which both the safing sensor SS3 and the ignition transistor Tr1 are in the ON state becomes long, the time required for ignition of the ignition element SC can be secured, and the airbag can be reliably deployed. .

As described above, in this embodiment, the time during which the contact of the reed switch is closed can be controlled, so that the airbag can be surely deployed. FIG. 5 is a sectional view of a reed switch according to a fourth embodiment of the present invention, (a) is an upper sectional view, (b) is a side sectional view, and (c) is a CC sectional view. FIG. 6 is a test flow of the safing sensor according to the fourth embodiment of the present invention.
(A) is a terminal connection diagram and (b) is a test flowchart. Hereinafter, description will be given with reference to the drawings.

First, the structure of the reed switch used in the safing sensor will be described. 4 is two magnetic leads 41, 42 and two non-magnetic leads 43, 4
The reed switch 4 (corresponding to a guide member) is sealed to the glass tube 45. Normally, the magnetic lead 41 and the non-magnetic lead 44 are in contact with each other, and the contact 414 is conductive. In addition, the magnetic lead 42 and the non-magnetic lead 43 are in contact with each other, and the contact 423
Is conducting. At the time of collision, a donut-shaped permanent magnet (not shown) overcomes the pressure of a spring (not shown), approaches the contact portion of the reed switch 4, and leads 41, 42 of the magnetic material.
The contact 4a formed between them is closed. At this time, the non-magnetic leads 43 and 44 do not react to the magnetic field generated by the magnet. Therefore, the contacts 414 and 423 are opened.
In this case, the leads 41 and 42 operate as the safing sensor SS4, and the leads 43 and 44 are the leads 4.
This is a test lead for judging whether or not 1, 42 are deformed. After they are assembled, they are sealed in the container.

After the safing sensor SS4 is assembled, the lead may deform due to impact or the like and may not operate normally. Therefore, the state of the contact part of the lead is checked according to the flow chart to determine whether it is normal or abnormal. I do. That is, when the leads 41 and 42 are largely deformed, the lead 4
Judgment is made based on the property of moving away from 3, 44. The terminal T41 of the safing sensor corresponds to the lead 41, and the terminals and leads of the other terminals also correspond to the same number.

In step S1, it is determined whether or not a collision is occurring. That is, this test is performed with the safing sensor turned off. Whether or not a collision is occurring is determined by comparing the voltage of the terminal T41 with the voltage of the terminal T42 when the safing sensor is on, and it can be determined that V1 = V2. In step S2, it is determined whether or not V1 = V4. If V1 = V4, the process proceeds to step S5, and V1
If not = V4, the process proceeds to step S3. That is, the terminal T
This is determined by comparing the voltage of 41 and the voltage of the terminal T44. If the lead is not deformed due to impact, etc.
Since 1 and the non-magnetic lead 44 are in contact with each other,
Both voltages should be equal.

In step S3, it is determined whether or not V2 = V3. If V2 = V3, the process proceeds to step S4 and V2
If not 2 = V3, the process proceeds to step S5. That is, the determination is made by comparing the voltage of the terminal T42 and the voltage of the terminal T43.
If the leads are not deformed due to shock or the like, the magnetic lead 42 and the non-magnetic lead 43 are in contact with each other, so that both voltages should be equal.

In step S4, it is determined that the safing sensor is normal. That is, since the magnetic lead 41 and the non-magnetic lead 44 are in contact with each other and the magnetic lead 42 and the non-magnetic lead 43 are in contact with each other, all the leads are deformed. You can judge that there is no. In step S5, it is determined that the safing sensor is abnormal. That is, since the magnetic lead 41 and the non-magnetic lead 44 are not in contact with each other and the magnetic lead 42 and the non-magnetic lead 43 are not in contact with each other, the leads are all deformed. Can be judged. still,
In order to distinguish it from the mere open state of the reed switch, the resistance R
It is desirable to enter the determination flow of this example after determining that the reed switch is normal from the voltage across 1.

As described above, in the present embodiment, not only the open / closed state of the reed switch but also the state of the contact point between the lead 41 and the lead 42 necessary for the reed switch cannot be directly tested, but the reed 41 and the lead 42 cannot be directly tested. 42 is a contact state with another lead 43, 44 of non-magnetic material
The deformation of 42 can be detected, and the reliability of the airbag is improved.

[0034]

As described above, according to the present invention, the contact failure of the contact portion of the reed switch used for the impact sensor is eliminated, and the closing time of the contact portion is lengthened.
It is possible to provide a highly reliable impact sensor by making it possible to perform an operation test of the contact portion.

[Brief description of drawings]

FIG. 1 is a diagram showing a structure of a reed switch used for a safing sensor according to a first embodiment of the present invention, (a) is an upper sectional view, (b) is a side sectional view, and (c) is B-. It is a B sectional view.

2A and 2B are diagrams illustrating a method of connecting terminals of a reed switch used in a safing sensor according to a second embodiment of the present invention, in which FIG. 2A is a perspective view and FIG. 2B shows a relationship between terminals and welding points. It is a figure.

FIG. 3 is a diagram illustrating a reed switch with a coil used in a safing sensor according to a third embodiment of the present invention.

FIG. 4 is a diagram illustrating an airbag start-up circuit using a reed switch with a coil according to a third embodiment of the present invention;
(A) is a starting circuit diagram, (b), (c) is a figure which shows the operating time of a safing sensor.

5A and 5B are sectional views of a reed switch according to a fourth embodiment of the present invention, where FIG. 5A is an upper sectional view, FIG. 5B is a side sectional view, and FIG. 5C is a sectional view taken along line CC.

FIG. 6 is a test flowchart of a safing sensor according to a fourth embodiment of the present invention, (a) is a terminal connection diagram, and (b) is a flowchart.

7A and 7B are views showing a structure of a reed switch used for a conventional safing sensor, FIG. 7A is an upper sectional view, FIG. 7B is a side sectional view, and FIG. 7C is a sectional view taken along line DD.

8A and 8B are diagrams illustrating a method of connecting terminals of a reed switch used for a conventional safing sensor, FIG. 8A is a perspective view showing a connected state of the reed switch, and FIG. 8B is a relationship between terminals and welding points. It is a figure.

FIG. 9 is a cross-sectional view showing the structure of a conventional safing sensor.

FIG. 10 is a diagram illustrating a conventional airbag starting circuit.

[Explanation of symbols]

 Tr1 ... Ignition transistor SC ... Ignition element R1 ... Test resistance 1, 2, 3, 4 ... Reed switch 6 ... Coil 7 ... Spring 8 ... Magnet

Claims (4)

[Claims] 1. A shock sensor comprising a reed switch, wherein a contact part of the reed switch is closed by a shock to the reed switch, wherein the reed switch has corresponding contact parts divided into a plurality of pairs. And shock sensor. 2. A shock sensor comprising a reed switch, wherein a contact portion of the reed switch is closed by a shock to the reed switch, wherein one end of an abnormality detection resistor is directly connected to one terminal of the reed switch, An impact sensor, wherein the other terminal of the abnormality detection resistor is directly connected to the other terminal of the switch. 3. An impact sensor comprising a reed switch, wherein a contact portion of the reed switch is closed by an impact on the reed switch, wherein the reed switch has an outer periphery of the reed switch corresponding to a contact portion of the reed switch. An impact sensor characterized in that it is connected in series to a coil wound around the portion. 4. An impact sensor comprising a reed switch, wherein a contact portion of the reed switch is closed by an impact on the reed switch, wherein the reed switch has a pair of reeds for opening and closing the contact portion, and the reed switch is always mutually An impact sensor comprising a pair of guide members which are spaced at a predetermined interval and which respectively come into contact with the leads in correspondence with each other.