JP2812997B2 - Acceleration detection switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] <Industrial Application Field> The present invention relates to a switch for detecting that a predetermined acceleration has been applied to a vehicle in order to activate a safety device in the event of a vehicle collision. .

<Conventional technology> Damage to the occupant during a vehicle collision includes not only the primary impact caused by colliding with a road structure or another vehicle, but also the secondary damage caused by the occupant colliding with a structure in the passenger compartment. There is something due to shock. In order to prevent this secondary collision, as a device for restraining the occupant from moving forward, an airbag device in which a bag that instantaneously expands due to gas pressure is interposed between the occupant and an obstacle, Various occupant restraint devices, such as a seat belt preloader device, have been proposed in which a restraint force on an occupant is increased by rapidly winding an end portion of a seat belt in a collision.

On the other hand, as a starting means for operating these occupant restraint devices, an inertial weight provided so as to be movable along a predetermined axis is always elastically supported at a predetermined position with a restoring force of a spring means. A switch is known in which the contact is closed by displacement of an inertial weight due to the action of deceleration at the time of a collision, and the above-described device is operated by an electric signal at this time.

Such a switch must be operated by accurately judging the impact peculiar to the collision, and in order to improve the response of the switch to a more appropriate one, an on-axis of a movable body having an appropriate inertial mass is used. In addition to providing a flat cup-shaped disk on the inner side of the casing, the inner surface of the axial end wall of the casing is provided with an occlusal surface where the peripheral edge of the disk can be in close contact, and within a predetermined impact range,
There has also been proposed a technique that can control the operation sensitivity of the switch by using the attraction force between the disc and the occlusal surface.

<Problems to be Solved by the Invention> However, the above-mentioned switch must be operated by accurately judging the deceleration inherent in the collision, but individual differences due to manufacturing errors or variations in materials may occur. Since it is difficult to avoid this, it is preferable to adopt a configuration in which the operation sensitivity can be easily adjusted.

Based on such a viewpoint, a main object of the present invention is to provide an acceleration detection switch improved so that individual differences in operation sensitivity caused by manufacturing errors or variations in materials can be suitably corrected. .

[Constitution of the Invention] <Means for Solving the Problems> According to the present invention, such an object is supported in a floating manner via one elastically biasing spring means along a predetermined axis, A sensor weight displaced to the other side along the predetermined axis by the action of acceleration is accommodated in a casing closed by a peripheral wall and an end wall in both axial directions, and one electrode connected to the sensor weight. And an acceleration detection switch configured to be electrically connected between the other electrode connected to the axial end wall on the other side and the sensor weight when an acceleration of a predetermined value or more is applied. A first plate for integrally receiving a suction plate having a plane orthogonal to the axis line on the sensor weight, wherein the casing receives an outer peripheral surface of the sensor weight and the outer peripheral surface of the suction plate in a non-contact manner; A second vacancy formed on the inner surface side of one of the axial end walls by bringing the outer peripheral edges of the chamber and the suction plate into close contact with each other by the urging force of the spring means; A resistance force is applied to the displacement of the sensor weight by the negative pressure formed in the sensor weight, and an adjusting means for arbitrarily setting the axial position of the sensor weight in a natural state is provided. This is achieved by providing an acceleration detection switch.

<Operation> In this way, the initial volume of the second chamber formed by the suction plate displaced together with the sensor weight can be changed according to the axial position of the sensor weight. Accordingly, the negative pressure formed in the second chamber changes, and the suction force of the suction plate can be changed, so that the operation sensitivity of the acceleration detection switch can be appropriately set.

Embodiments Hereinafter, the present invention will be described in detail with reference to the accompanying drawings with reference to specific embodiments.

FIG. 1 shows an acceleration detection switch configured according to the present invention. Acceleration detection switch casing 1
Consists of a rear half 1a having a generally bottomed cylindrical shape formed by injection molding of a synthetic resin, and a front half 1b that hermetically closes an opening of the rear half 1a. Body 1a,
1b are integrally joined with a spring member 2 sandwiched between opposing surfaces.

As shown in FIG. 2, the spring member 2 has a pair of spiral cuts 3 formed in a circular phosphor bronze plate from the center outward.
And a sensor weight 4 having a columnar shape and a predetermined inertial mass at the center thereof.
Is fixed by brazing or the like.

At the axial end of the sensor weight 4 on the side fixed to the spring member 2, a projection 5 extending in the axial direction penetrates the center of the spring member 2, and is opposite to the axial end. Is formed with a guide rod 6 having a reduced diameter. The guide rod 6 is loosely fitted in a guide hole 7 formed in the center of the bottom wall of the rear half 1a, and defines a movement axis of the sensor weight 4 in cooperation with the spring member 2. In this manner, the sensor weight 4 is configured to be movable only in the axial direction while receiving the elastic urging force of the spring member 2, and is normally held at a position corresponding to the restoring force of the spring member 2. A tongue piece 2a is provided at an appropriate position on the outer peripheral portion of the spring member 2 so as to protrude outward from the casing 1 in a radially outward direction, and constitutes one electrode together with the protrusion 5 of the sensor weight 4. doing.

An inner screw is provided in the guide hole 7, and an adjusting screw 8 is screwed therein. When the adjusting screw 8 is advanced and retracted, the substantial depth dimension of the guide hole 7 can be changed, whereby the guide rod 6 of the sensor weight 4 can be changed.
Positioning is performed in the axial direction of the end.

On the inner surface of the bottom wall of the rear half 1a, an annular ridge 9 protruding from the guide hole 7 is formed, and a concave portion 10 is formed inside the annular ridge 9.

At the base of the guide rod 6 with respect to the sensor weight 4, a disk-shaped suction plate 11 made of a highly flexible Teflon resin or the like is provided between a backup plate 12 made of a phosphor bronze plate and a highly rigid retainer plate 13. It is fixed so as to be clamped by the. The suction plate 11 is configured to be in close contact with the circumference of the top of the annular ridge 9 at the outer peripheral portion thereof, and the close contact force is supported by the urging force of the backup plate 12. Also, retainer plate 13
Is fixed on the contact surface of the suction plate 11 with the annular ridge 9 so as not to be in contact with the inner peripheral surface of the concave portion 10, whereby the amount of bending of the outer peripheral portion of the suction plate 11 is defined. I have. When the suction plate 11 abuts against the annular ridge 9 in an airtight manner, two cavities 14a and 14b are formed inside the casing 1.

Inside the bottom wall of the rear half 1a, a radial hole 15a and an annular protrusion communicating between the outer periphery of the rear half 1a and the center of the recess 10 so that the two cavities 14a and 14b can communicate with each other. A bypass passage 15 comprising an axial hole 15b drilled outside the ridge 9 is provided. The communication degree of the bypass passage 15 can be adjusted by a needle valve 16 screwed into an opening on the peripheral wall of the rear half 1a.

The central portion 17 forming the end wall of the front half 1b and the outer peripheral portion 18 forming the peripheral wall are screwed to each other so as to be relatively displaceable in the axial direction. On the inner surface of the central portion 17, a pair of protrusions 19a, 19b are provided at equal distances from the center and project diagonally, and the tips of the protrusions 19a, 19b are
The outer peripheral portion of the spring member 2 can be brought into contact with an appropriate position. By pushing the central portion 17 forward and backward with respect to the outer peripheral portion 18, the pressing force of the two projections 19 a and 19 b against the spring member 2 changes, whereby the elastic force of the spring member 2 against the sensor weight 4 changes. I do.

A terminal plate 20 is insert-molded in a central portion of the central portion 17. The terminal plate 20 is bent substantially in an L shape, and includes a terminal portion 20a along the axial direction and a retainer portion 20b orthogonal to the axis. The retainer portion 20b is located at the center portion.
It protrudes cantilevered into an opening 17a opened in the center of 17. The retainer portion 20b is provided with a hole 21 into which the projection 5 of the sensor weight 4 can be loosely fitted.
The lead piece 22 is fixed so as to close from the outer surface side. The lead piece 22 is configured to be tiltable toward the outside of the central portion 17 with a fixing point to the retainer portion 20b as a fulcrum.
Close to. The terminal plate 20 and the lead piece 22 constitute the other electrode.

The free end of the retainer portion 20b is in contact with the tip of a push screw 23 screwed to the central portion 17 of the front half 1b. When the push screw 23 is advanced and retracted, the retainer portion 20b is tilted, whereby the axial position of the lead piece 22 is changed to some extent, and the distance between the tip of the protrusion 5 of the sensor weight 4 and the lead piece 22 is changed. The distance can be adjusted.

The opening 17a is filled with a foam material 24 having relatively low elasticity. This prevents the sensor weight 4 from being repelled by the resilience of the lead piece 22 when the projection 5 of the sensor weight 4 hits the lead piece 22.

By the way, at the time of a collision of a vehicle, a large impact load acts in a short time. However, a switch for detecting a collision cannot reliably detect a shocking deceleration peculiar to the vehicle at the time of the collision. No. That is, there is a need to be able to accurately discriminate a deceleration caused by a collision from a deceleration that has a relatively long duration due to a braking device and a momentary deceleration that a wheel receives from unevenness of a road surface.

By the way, the displacement response of a spring made of a flexible material is as follows.
Although relatively sensitive to momentary loads,
The response to a slowly acting load tends to be relatively slow. On the other hand, the resistance force of the fluid has a property that it acts more as the moving speed is higher. Therefore, as shown in the above-described embodiment, a configuration is adopted in which the sensor weight 4 resiliently supported by the spring member 2 is provided with the fluid resistance of air by the suction plate 11 which is displaced integrally with the sensor weight 4. Accordingly, it is possible to set the operation characteristics of the switch such that only the sensitivity to the deceleration in a specific area at the time of a vehicle collision becomes sharp.

According to the above embodiment, normally, the sensor weight 4 is held by the biasing force of the spring member 2, and at the same time, the suction plate 11 is pressed against the annular ridge 9 via the back-up plate 12. As a result, the air in the empty space 14b in the concave portion 10 is eliminated, and the suction plate 11 is sucked to the annular ridge 9.

Here, when deceleration acts on the vehicle, the casing 1 tries to stop together with the vehicle, whereas the sensor weight 4 elastically supported by the casing 1 via the spring member 2 causes the vehicle to lose its inertia force. Try to move in the direction of travel. Along with this, the suction plate 11 is
However, since the suction plate 11 is pressed against the annular ridge 9 by the backup plate 12, the internal pressure of the concave portion 10 is reduced, and the suction plate 11 acts as a resistance for preventing the sensor weight 4 from moving. I do. When a sufficiently large and long deceleration is applied, the retainer plate 13
The peripheral edge of the suction plate 11 is separated from the annular ridge 9. Then, the sensor weight 4 is released from the suction force of the suction plate 11 due to the negative pressure in the concave portion 10, and the elastic resistance given by the spring member 2 and the fluid resistance given by the suction plate 11 moving in the air. It moves based on the determined sensitivity characteristic, and is displaced until the projection 5 of the sensor weight 4 hits the lead piece 22. As a result, the tongue piece 2a and the terminal 20
Conduction is made between the two electrodes a and the occupant restraint device is separately activated by the drive device.

In such a switch, it is difficult to completely eliminate the individual difference caused in manufacturing. In the present invention, the adjusting screw 8 is inserted into the guide hole 7 in which the guide rod 6 of the sensor weight 4 is loosely fitted. The adjusting screw 8 defines the normal axial position of the guide rod 6 to vary the substantial displacement stroke of the sensor weight 4 due to the action of the deceleration, and at the same time, the space 14b in the recess 10 Of the suction plate 11 can be changed to change the degree of suction of the suction plate 11 to the annular ridge 9. In the case of the above embodiment, the sensor weight 4
Of the spring member 2 by changing the displacement stroke of
The restoring force of the sensor weight 4 also changes at the same time, but the operating sensitivity and the damping characteristic of the sensor weight 4 may be set in consideration of these factors.

In the above embodiment, the degree of communication between the two cavities 14a and 14b, the position of the lead piece 22, and the pressing force against the spring member 2 can be simultaneously adjusted. Are not necessary, and these can be appropriately combined and configured in various modified modes so that desired sensitivity characteristics can be obtained more accurately.

[Effect of the Invention] As described above, according to the present invention, with an extremely simple structure,
Since the damping characteristics of the sensor weight can be easily changed, it is possible to adjust the operation sensitivity of the acceleration detection switch, effectively eliminate variations in response due to individual differences, and improve the reliability of the acceleration detection switch. There is a great effect on further improving.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing the entire acceleration detecting switch according to the present invention. FIG. 2 is an end view along the line II-II in FIG. DESCRIPTION OF SYMBOLS 1 ... Casing, 1a ... Back half 1b ... Front half 2, ... Spring member 2a ... Tongue, 3 ... Cut 4 ... Sensor weight, 5 ... Projection 6 ... Guide rod, 7 Guide hole 8 Adjusting screw 9 Annular ridge 10 Recess 11 Adsorption plate 12 Backup plate 13 Retainer plate 14 a, 14 b Vacant room 15 Bypass passage 15a ... radial hole, 15b ... axial hole 16 ... needle valve, 17 ... central part 17a ... opening, 18 ... outer peripheral part 19a, 19b ... protrusion, 20 ... terminal plate 20a ... terminal Part, 20b ... retainer part 21 ... hole, 22 ... lead piece 23 ... set screw, 24 ... foam

Claims (1)

(57) [Claims] A sensor weight, which is floatingly supported by a spring means which resiliently urges one side along a predetermined axis and is displaced to another side along the predetermined axis by the action of acceleration, is provided on a peripheral wall. And housed in a casing closed by both axial end walls, and between one electrode connected to the sensor weight and the other electrode connected to the other axial end wall. An acceleration detection switch configured to be conductive by a displacement of the sensor weight when an acceleration equal to or more than a predetermined value acts, wherein the sensor weight is integrally provided with a suction plate having a plane perpendicular to the axis. A first chamber in which the casing receives the sensor weight and an outer peripheral surface of the suction plate in a non-contact manner, and an outer peripheral edge of the suction plate come into close contact with the biasing force of the spring means; The made Guo on the inner surface of one of the axial end wall with a 2
The negative pressure formed in the second empty chamber applies a resistance to the displacement of the sensor weight, and the axial position of the sensor weight in a natural state can be arbitrarily set. An acceleration detection switch, comprising an adjusting means that can be set.