JP3328677B2 - Acceleration detection switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an acceleration detection switch for detecting acceleration.

[0002]

2. Description of the Related Art An acceleration detection switch is used, for example, as a collision sensor for detecting a collision of an automobile. When an acceleration applied to the acceleration detection switch exceeds a detection level during a collision of the automobile, the acceleration detection switch is turned on. And outputs a detection signal to the controller.
In response to the detection signal, the airbag is activated, or the door is locked or the door is unlocked.

[0003]

In such a system, in order to reliably detect the collision of an automobile and activate the airbag, or to lock or unlock the door, a collision sensor is required in such a system. It is desirable that the ON period of the detection signal given from the acceleration detection switch to the controller be sufficiently long.

[0004] In addition, in the case of an automobile collision, the magnitude of the applied acceleration differs depending on whether the collision is a frontal collision, a side collision, or a rear collision. It is desired that one acceleration detection switch can detect a collision of each surface.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has an advantage in that an output period of a detection output can be lengthened, and acceleration can be detected at different detection levels according to the direction of the applied acceleration. The purpose is to be able to.

[0006]

In order to achieve the above-mentioned object, the present invention is configured as follows.

That is, the acceleration detection switch of the present invention comprises a sphere housed in a case, a reversing spring as a movable contact which is pressed by the movement of the sphere and urges the sphere , and a reversing spring. A fixed contact that is disposed on the opposite side to the sphere side and comes into contact with and separates from the reversing spring. The reversing spring is pressed via an operating body that is tilted and displaced by the movement of the sphere, and The spring reverses to the fixed contact side when the pressing force due to the movement of the sphere reaches a first pressing force, and when the pressing force reaches a second pressing force smaller than the first pressing force, the sphere side And return to inversion.

[0008]

[0009]

[0010] An inclined recess is formed on the upper surface of the operating body,
The operating body may be inclinedly displaced by the sphere moving on the inclined recess.

An inclined recess may be formed in the upper surface of the case, and the reversing spring may be pressed by the movement of the sphere along the inclined recess.

[0012]

[0013]

[0014] The fixed contact may be made of a material having a spring property so as to bend in accordance with contact and separation with the reversing spring.

[0015]

[0016]

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a side view of an automobile equipped with an acceleration detection switch according to an embodiment of the present invention as a collision sensor. The automobile 1 is provided with an airbag system and a door lock system. I have.

FIG. 2 is a block diagram showing a configuration for operating the airbag system and the door lock system of the automobile 1. As shown in FIG. The acceleration detection switch 2 according to this embodiment includes:
The controller 3 detects the acceleration at the time of collision of the automobile 1 and outputs a detection signal (ON signal), and the controller 3 operates the airbag system 4 and the door lock system 5 in response to the input of the detection signal. ing.

FIG. 3 is a side view of the acceleration detecting switch, and FIG. 4 is a sectional view thereof.

The acceleration detecting switch 2 of this embodiment includes a reversing spring 9 as a movable contact inside a case 8 comprising a substantially disk-shaped base 6 and a cylindrical cover 7 having an open lower end. It has a push button 10 as an operating body and a steel ball 11 made of steel.

The base 6 is provided with four movable contact terminals 12 whose upper ends slightly protrude above the base 6 and whose lower ends protrude below the base 6 at intervals of approximately 90 degrees at the peripheral edge thereof. Further, a fixed contact terminal 13 whose upper end is in contact with and separates from the reversing spring 9 as a fixed contact 13a and whose other end protrudes downward is provided at the center thereof.

On the base 6, on each movable contact terminal 12, a circular reversal spring 9 whose peripheral edge is fixed and which is circular in a plan view is provided so as to be curved so as to expand upward. On the reversing spring 9, a push button 10 having a predetermined thickness in a circular shape in plan view is mounted. The push button 10 has a downwardly projecting portion 10 a in the center of the lower surface, and the periphery thereof is depressed by the spring force of the reversing spring 9 so that the projecting portion 10 a is pressed upward. It is engaged with the surface. The push button 10 has a conical inclined recess 10b having a uniform inclined surface at the center of the upper surface, and the steel ball 11 has an inclined recess of the push button 10 in an initial position where no acceleration is applied. 10b, the upper side is in contact with the upper surface in the case 8 in the state of entering.

In the acceleration detection switch 2 having such a structure, assuming that the automobile 1 has collided, the acceleration G in the direction of the arrow due to the collision acts on the acceleration detection switch 2 as shown in FIG. Then, the steel ball 11 in the case 8 moves in the inclined recess 10b of the push button 10, and the push button 10 is pushed downward against the upward biasing force of the reversing spring 9 corresponding to the moving direction of the steel ball 11. To be displaced. Due to the inclination displacement of the push button 10, the reversing spring 9 is pressed against the urging force by the convex portion 10a of the push button 10, and when the reversing spring 9 reaches a first pressing force described later, the reversing spring 9 is instantaneously moved. The fixed contact 13 at the upper end of the fixed contact terminal 13 is turned downward as shown in FIG.
a, and the acceleration detection switch 2 is turned on.

Next, after the collision, the acceleration with respect to the acceleration detection switch 2 is attenuated, so that the steel ball 11 is pressed via the push button 10 by the spring force of the reversing spring 9 . Therefore, the steel ball 11 moves in the inclined recess 10b of the push button 10 so as to return from the state of FIG. 5 to the state of FIG. When the concave pressure becomes a second pressing force described later, the reversing spring 9 instantaneously reverses and returns upward, and as shown in FIG. 4, the reversing spring 9 is fixed to the fixed contact 13a at the upper end of the fixed contact terminal 13. And the acceleration detection switch 2 is turned off.

The second pressing force at which the reversing spring 9 reverses and returns is smaller than the first pressing force, and accordingly, a period from when the acceleration detection switch 2 is turned on to when it is turned off (on period). ) Is longer.

The characteristics of the reversing spring 9 are shown in FIGS.
This will be described in more detail based on

FIG. 6 shows the on / off state of the switch when a load is applied to the reversing spring 9 of this embodiment. FIG. 6A shows the output state of the switch, and FIG. ) Indicates the load. FIG. 7 shows the relationship between the load at that time and the stroke of the reversing spring 9.

As shown in these figures, when the load is
When the load a corresponding to the pressing force is reached, the reversing spring 9
The switch is turned on by instantly reversing to the fixed contact side,
When the load attenuates and reaches the load b corresponding to the second pressing force, the reversing spring 9 instantaneously reverses and returns, and the switch is turned off.

The load b at which the reversing spring 9 reverses and returns is smaller than the load a at which the reversing spring 9 reverses.
Since the switch has a so-called hysteresis characteristic, the on-period of the switch is longer than in the case where the switch is reversed by the load a.

Further, in this embodiment, when the acceleration is attenuated, the urging force of the reversing spring 9 acts on the steel ball 11 via the push button 10 which is tilted and displaced, so that the steel ball 11
Is returned to the original initial position, so that the ON period can be further lengthened.

That is, in the state of FIG. 4 where the push button 10 is not tilted and displaced, the inclined recess 10
The inclination angle of b with respect to the horizontal plane is α, and push button 1
In the state of FIG. 5 where 0 is inclined and displaced, the inclination angle of the inclined concave portion 10b of the push button 10 is β smaller than the above α, and in FIGS. The force to return to the position will be different.

This will be described in more detail with reference to FIG. FIG. 3A shows the return force F2 acting on the steel ball 11 in the direction of the arrow when the push button 10 is not inclined and the inclination angle of the inclined concave portion 10b is α.
FIG. 2B shows that the push button 10 is inclined and the inclined recess 1 is formed.
The return force F3 acting on the steel ball 11 in the direction of the arrow when the inclination angle of 0b becomes β is shown.

That is, the push button 10 is turned by the reversing spring 9.
, An urging force F1 acts on the push button 10. At this time, since the steel ball 11 is sandwiched between the upper surface in the case 8 and the push button 10,
This urging force F1 causes return forces F2 and F3 in the direction of the arrows to act on the steel ball 11, respectively. However, when the inclination angle of the inclined recess 10b of the push button is β smaller than α,
The return force F3 in the direction of the arrow becomes smaller.

As a result, when the steel ball 11 returns from the state shown in FIG. 5 to the state shown in FIG. 4 in the inclined recessed portion 10b of the push button 10, the push button 10 is tilted by the steel ball 11 because the returning force is small. The time required to return from the state of the angle β to the state of α, that is, the time during which the steel ball 11 pushes the push button 10 to the inclined state becomes longer. (On period) is longer.

Next, the on / off operation of the acceleration detecting switch 2 having the above configuration will be described in more detail with reference to FIG.

Referring to FIG.
, The load applied to the acceleration detection switch 2 corresponding to the acceleration, and the on / off output of the acceleration detection switch 2 are shown.

When the load increases with an increase in the applied acceleration and the steel ball 11 moves, the reversing spring 9 is pressed. When the reversing spring 9 reaches a detection line corresponding to the first pressing force, the reversing spring 9 is moved. When the acceleration detection switch 2 is turned on by rapidly reversing and contacting the fixed contact 13a, the acceleration is attenuated, the load decreases, and when the second pressing force lower than the detection line is reached, the reversing spring 9 is turned on. The acceleration detection switch 2 is turned off rapidly after being reversed and separated from the fixed contact 13a.

As described above, there is a difference Δ between the load at which the reversing spring 9 is reversed and the acceleration detecting switch 2 is turned on and the load at which the reversing spring 9 is reversed and the acceleration detecting switch 2 is turned off. The ON period when the acceleration is applied becomes longer, whereby the collision of the vehicle 1 can be reliably detected and the airbag system 4 and the door lock system 5 can be activated.

In the above embodiment, the push button 10 is formed with a conical inclined recess 10b so that the push button 10 is inclined and displaced by the movement of the steel ball 11, but as another embodiment of the present invention. , as shown in FIGS. 10 and 11, the upper surface of the push button 10 ₁ is a planar, the upper surface of the case 8 to form a conical inclined recesses 8a, by application of acceleration G as shown in FIG. 11 button 10 ₁ pressed by the movement of the steel ball 11 may be inclined displacement. Other configurations and operations are than is similar to the embodiment described above, description thereof will be omitted.

The acceleration detecting switch 2 of this embodiment
₁ and the acceleration detecting switch 2 of the above-described embodiment, the movable contact terminal 12 and the fixed contact terminal 13 protruding below the base 6 are connected to the printed circuit board 14 as shown in FIGS. It is a connector terminal for mounting.

Each of the acceleration detection switches 2 and
2 ₁ fixed contact terminal 13, but did not have a spring property, as another embodiment of the present invention, as shown in FIGS. 12 and 13, the terminals 13 ₁ fixed contact, the reverse spring 9 may be constituted by a bent member having a spring property that bends in accordance with the contact and separation of the inversion spring 9. According to such a configuration, the momentum of the inversion spring 9 when the inversion spring 9 instantaneously inverts is used by the spring property. by absorbing, it is possible to prevent chattering, moreover, as shown in FIG. 13, when the acceleration detection switch 2 ₂ is turned on by the acceleration G, the fixed contact 13 ₁ a of the fixed contact terminals 13 ₁ , And bends deeply downward, and the ON period can be further lengthened.

In each of the above-described embodiments, the acceleration detection switch 2,
2 ₁ and 2 ₂ have no direction in the detection level,
In the case of a car collision, the magnitude of the applied acceleration differs depending on whether the collision is a front, side, or back collision, so that a single acceleration detection switch can detect the collision on each surface. Is desired.

FIG. 14 shows acceleration waveforms in a frontal collision and a side collision. FIG. 14 shows acceleration waveforms of a high-speed frontal collision, E shows a medium-speed frontal collision, and F shows an acceleration waveform of a side collision. I have.

As is apparent from FIG.
The applied acceleration is smaller than in the case of a head-on collision. Therefore, in order to detect a side collision, the detection level must be set lower, that is, the sensitivity must be increased. Even if the vehicle is suddenly stopped by a brake, the vehicle will malfunction as a collision. Conversely, if the sensitivity is lowered to eliminate the malfunction due to the sudden brake, a side collision cannot be detected.

Therefore, an acceleration detection switch having a different detection level is desired depending on whether the collision is a frontal collision or a side collision, that is, according to the direction of the applied acceleration.

[0047] Figure 15 is a diagram showing the acceleration detection switch 2 ₃ of another embodiment of the present invention has been made in view of the above, FIG. (A) is a sectional view showing the upper surface of the case 8 FIG. 2B is a cross-sectional view taken along line BB of FIG. 2A, and FIG. 2C is a cross-sectional view taken along line CC of FIG. 2A. Parts corresponding to the above-described embodiments are denoted by the same reference numerals.

The acceleration detection switch 2 ₃ of this embodiment,
It detects a frontal collision and a side collision, and has a detection level corresponding to each of the frontal collision and the side collision.

[0049] That is, the acceleration detection switch 2 ₃ of this embodiment, the center portion of the upper surface of the case 8, i.e., the center of the upper surface of the cover 7 _2, the inclination angle is uniform conical section 7 ₂ a
When, as this conical part 7 ₂ a has an inclined recess 7 ₂ c made of a frustoconical portion 7 ₂ b successive frustoconical portions 7 ₂ b is shown in FIG (A), It is formed in an elliptical shape in plan view. The inclination angle of the elliptical truncated cone portion 7 ₂ b is α _{1 in the} cross section shown in FIG. 6B, and is smaller than α _{1 in the} cross section shown in FIG. and it has a β _1. The center where the major axis and the minor axis of the ellipse intersect corresponds to the center of the upper surface of the case 8, that is, the initial position of the steel ball 11.

[0050] Here, the acceleration detection switch 2 ₃ 1
In the front-rear direction (left-right direction in FIG. 1) of the automobile 1 shown in FIG.
The cut surface line C- in FIG. 15B is aligned with the cut surface line BB in FIG. 15A, that is, in the direction perpendicular to the front-rear direction of the vehicle 1 (the direction perpendicular to the paper surface of FIG. 1). C are arranged along.

That is, FIG. 15B is a cross-sectional view along the traveling direction of the automobile 1, and FIG. 15C is a cross-sectional view along a direction orthogonal to the traveling direction.

[0052] In the acceleration detection switch 2 ₃ of this embodiment, as described above, in the cross section of the angle of inclination of the frustoconical portion 7 ₂ b, along the direction of travel, large, in the cross section along the direction orthogonal to the running direction, Since the inclination angle is changed so as to be small, the magnitude of the acceleration required to move the steel ball 11 is large in the traveling direction for detecting a head-on collision, Becomes smaller in a direction orthogonal to the traveling direction for detecting

That is, in the traveling direction of the automobile 1, the detection level for detecting a head-on collision is high (the sensitivity is low).
In the direction perpendicular to the traveling direction, the detection level for detecting a side collision is low (high sensitivity), which can reliably detect a side collision and a front collision, respectively. If there is, there is no malfunction.

Other structures and operations are the same as those of the above-described embodiment, and the description thereof will be omitted.

FIG. 16 is a view corresponding to FIG. 15 of another embodiment of the present invention, and portions corresponding to the embodiment of FIG. 15 are denoted by the same reference numerals.

In the embodiment shown in FIG. 15, the upper surface of the case 8
I sand, the upper surface of the cover 7 _2, although to form an inclined recess 7 ₂ c, in this embodiment, instead of the inclined recess 7 ₂ c, the upper center portion, circular shape in plan view of the depth L1 the first recess 7 ₃ a and forms a recess 7 ₃ c composed of a second recess 7 ₃ b in plan view oval depth L2 (L1> L2) around it, each recess 7 ₃ a of , the boundary of 7 ₃ b is formed with a step.

In this embodiment, the elliptical second concave portion 7 ₃ b
Is formed such that its minor axis a is along the traveling direction of the vehicle 1 and its major axis b is along a direction orthogonal to the traveling direction. In the state where no acceleration is applied, the steel ball 11 is in contact with the peripheral edge of the second concave portion 7 ₃ b on the short diameter a side as shown in FIG. As shown in FIG.
Spaced from the peripheral edge of the second recess 7 ₃ b.

As described above, the minor axis a of the elliptical second concave portion 7 ₃ b is positioned in the traveling direction for detecting a frontal collision, and the major axis b is positioned in the direction orthogonal to the traveling direction for detecting a side collision. Therefore, the magnitude of the acceleration required to move the steel ball 11 is large in the traveling direction for detecting the frontal collision, and is orthogonal to the traveling direction for detecting the side collision. Direction becomes smaller.

That is, in the traveling direction of the automobile 1, the detection level for detecting a frontal collision is high (low sensitivity), and in the direction orthogonal to the traveling direction, the detection level for detecting a side collision is low (sensitivity). This makes it possible to reliably detect a side collision and a frontal collision, respectively, and does not malfunction a sudden stop due to a sudden brake as a collision.

Other structures and operations are the same as those of the above-described embodiment, and the description thereof will be omitted.

In each of the above-described embodiments, the inclined concave portion 7 ₂ c or the concave portion 7 ₃ c is formed in an elliptical shape. However, in another embodiment of the present invention, the detection level varies depending on the direction in which the detection level is to be changed. For example, the shape may be an arbitrary shape such as a substantially triangular shape, a substantially square shape, or a substantially pentagonal shape.

In each of the embodiments described above, the inclined concave portion 7 ₂ c or the concave portion 7 ₃ c is formed on the upper surface in the case 8 so that the detection level has directionality. However, as another embodiment of the present invention, , Instead of the upper surface in the case 8,
It is a matter of course that an inclined concave portion or a concave portion may be formed on the upper surface of 10 ₁ so as to give directionality to the detection level.
For example, _one of the upper surfaces of 0 and 101 is provided with an inclined concave portion having a uniform inclined surface as shown in FIG. 12, and the other is provided with an inclined concave portion or concave portion for giving directionality to the detection level. It may be provided.

[0063]

As described above, according to the present invention, the reversing spring as the movable contact has a pressing force due to the movement of the sphere of the first type.
When the first pressing force is reached, it is instantaneously reversed to the fixed contact side, and when the second pressing force smaller than the first pressing force is reached, it is instantaneously reversed and returned to the sphere side. Until the second pressing force, which is smaller than the pressure, is reached, the contacts are kept on, so that the period of the detection output, that is, the on-period can be lengthened, which is particularly suitable as a vehicle collision sensor.

In addition, since the reversing spring is pressed via the operating body which tilts and displaces, the return force acting on the sphere from the reversing spring via the operating body differs depending on the amount of tilt displacement. , The ON period can be further lengthened.

Further, according to the present invention, it is possible to give directionality to the acceleration detection level, so that acceleration in different directions can be detected at different detection levels by a single acceleration detection switch. In particular, it is suitable as a collision sensor for an automobile in which the acceleration applied differs depending on the direction of the collision.

Further, according to the present invention, since the fixed contact has a spring property so as to bend in accordance with the contact and separation with the reversing spring as the movable contact, chattering can be effectively prevented, and at the time of contact with the movable contact. The fixed contact is deeply bent together with the movable contact, so that the ON period can be further lengthened.

[Brief description of the drawings]

FIG. 1 is a side view of an automobile equipped with an acceleration detection switch according to one embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration for operating an airbag and a door lock system of the automobile shown in FIG. 1;

FIG. 3 is a side view of the acceleration detection switch of FIG. 2;

FIG. 4 is a cross-sectional view of the acceleration detection switch of FIG.

FIG. 5 is a cross-sectional view in a state where acceleration is applied.

FIG. 6 is a diagram showing an on / off state of a switch when a load is applied to the reversing spring of FIG. 4;

FIG. 7 is a characteristic diagram showing a relationship between a load and a stroke of a reversing spring in the state of FIG. 6;

FIG. 8 is a diagram showing a magnitude of a return force acting on a steel ball from a reversing spring.

FIG. 9 is a diagram illustrating operation characteristics of the acceleration detection switch.

FIG. 10 is a cross-sectional view corresponding to FIG. 4 of another embodiment of the present invention.

FIG. 11 is a sectional view corresponding to FIG. 5 of the embodiment of FIG. 10;

FIG. 12 is a sectional view of still another embodiment of the present invention.

FIG. 13 is a sectional view corresponding to FIG. 5 of the embodiment of FIG. 12;

FIG. 14 is a characteristic diagram showing the magnitude of acceleration in a frontal collision and a side collision.

FIG. 15 is a sectional view of another embodiment of the present invention.

FIG. 16 is a sectional view of still another embodiment of the present invention.

[EXPLANATION OF SYMBOLS] 1 automotive 2,2 ₂₁ to ₂₄ the acceleration detection switches 7 ₂ c inclined recess 7 ₃ c recesses 8 case 8a inclined recess 9 reversing spring 10 push-button 10b inclined recess 11 steel balls 13a, 13 ₁ a fixed contact

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-157765 (JP, A) JP-A-49-48369 (JP, A) JP-A-5-64018 (JP, U) JP-A-62 197235 (JP, U) Jikken 48-13547 (JP, Y1) Jikken 50-19153 (JP, Y1) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01P 15/135 H01H 35 / 14 G01H 1/00-1/16

Claims (5)

(57) [Claims] And 1. A is accommodated in the case a sphere, while being pressed by the movement of the spheres, the inversion spring as the movable contact for urging the spherical side, opposite to the sphere side of the reverse spring And a fixed contact that is disposed in contact with and separates from the reversing spring. The reversing spring is pressed via an operating body that is inclined and displaced by the movement of the sphere, and the reversing spring is moved by the movement of the sphere. The pressing force is the first
The acceleration detection switch reverses to the fixed contact side when the pressing force reaches the second pressing force and returns to the sphere side when reaching the second pressing force smaller than the first pressing force. 2. The acceleration detection switch according to claim 1, wherein an inclined recess is formed on an upper surface of the operating body, and the reversing spring is pressed by movement of the sphere along the inclined recess. 3. The acceleration detection switch according to claim 1, wherein an inclined recess is formed on an upper surface in the case, and the reversing spring is pressed by movement of the sphere along the inclined recess. 4. The acceleration detection switch according to claim 1, wherein a recess having a planar shape is formed on an upper surface in the case according to a direction in which an acceleration detection level is made different. 5. The acceleration detection switch according to claim 1, wherein the fixed contact has a spring property so as to bend in accordance with the contact and separation with the reversing spring.