JPS62198762A - Reduced speed sensor - Google Patents

Abstract

PURPOSE:To generate a signal for a long period by providing a projection part which supplies a motion component to a sensing mass which moves at right angles to its moving direction. CONSTITUTION:A reduced speed sensor 1 is fitted to a vehicle body so that a cap 4 is in the front in the running direction of the vehicle; and the sensing mass 9 is held by a magnet 10 in contact with the rear end surface 8 of a guide path 6. If the vehicle body is reduced greatly in speed owing to a collision, etc., an inertial force operates on the mass 9 in the running direction and the mass 9 moves forth to abut on the projection part 18 provided on the guide surface 4a of the cap 4. Then, the mass 9 is given a motion component at right angles to the moving direction to move slantingly. Then, the mass 9 abuts on the other projection part 20 to enter slanting motion and is bounded by the front end surface 7 to abut on the projections 20 and 18; and the backward motion is attenuated and the time from the contacting of the mass 9 with contacts 14 and 15 to its leaving is held long and the signal is generated for the long period.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a deceleration sensor mounted on a vehicle such as an automobile, and particularly relates to a deceleration sensor that uses a sensing mass that moves when deceleration of a predetermined value or more occurs. , relates to a deceleration sensor in which an output signal is generated.

(Conventional technology) For vehicles such as automobiles, as an occupant protection device.

It is equipped with airbags and seat belts.

Many of these airbags and seat belts are designed to be activated in response to the deceleration that occurs in the vehicle body during a vehicle collision. A sensor is installed.

Generally, such deceleration sensors include a sensing mass that moves due to inertial force and an output contact that is closed by the movement of the mass. The sensing mass is normally held at the rear end of the guideway, and is configured to move toward the front end along the guideway when the vehicle body decelerates to a predetermined value or more. An output contact is provided at the front end of the guideway.

By the way, in such a deceleration sensor, when a large deceleration occurs in the vehicle body, the sensing mass that has moved along the guide path is bounced back by the front end surface of the guide path. Therefore, the closing time of the output contact provided at the front end of the guide path is extremely short. On the other hand, in order to activate an airbag or the like, the signal output from the deceleration sensor is required to continue for about 2 m5ec.

Therefore, a deceleration sensor that damps the motion of a sensing mass has been devised, as disclosed in, for example, Japanese Patent Laid-Open No. 57-813. This deceleration sensor has a housing with a tubular guideway that is sealed from the outside. The sensing mass has a slightly smaller diameter than the guide path. Further, the sensing mass is formed of a magnetic material and is attracted to the rear by a magnet attached to the rear end of the housing. Furthermore, the front end of the guideway has a larger cross-sectional area,
When the sensing mass contacts the contact point, a space in front of the mass and a space behind the mass communicate with each other through a relatively large gap.

In such deceleration sensors, the sensing mass is usually held at the rear end of the guideway by the magnetic force of a magnet, and when the housing decelerates beyond a predetermined value, it is released from the restraint by the magnetic force of the magnet. Leave and move forward. At that time, the sensing mass is subjected to a damping force due to the flow resistance of the fluid flowing through the small gap between the sensing mass and the guide path and the magnetic force of the magnet. In addition, when the sensing mass reaches the state where it comes into contact with the output contact, the fluid compressed on the front side flows into the guideway on the rear side, so even if the sensing mass is bounced back by the front end face of the guideway. ,
The fluid applies a damping force to the motion of the sensing mass.

(Problems to be Solved by the Invention) In such a deceleration sensor, it is necessary to make the time from when the vehicle body decelerates until the output contact is closed as short as possible. Therefore, the forward movement of the sensing mass until contacting the contact cannot be damped too much. However, if the damping force is too small, the mass will be strongly bounced back by the front end of the guideway. For this reason, in the deceleration sensor as shown in the above-mentioned publication, if the contact is to be closed for a predetermined period of time, the length and inner diameter of the guide path, the mass and outer diameter of the sensing mass, the magnet's It is necessary to set magnetic force etc. extremely accurately. Moreover.

Since the rebound of the sensing mass tends to be facilitated by the magnetic force of the magnet, it is difficult to make the contact closure time longer.

The present invention has been made in view of such problems, and its purpose is to provide a deceleration sensor as described above.
The purpose is to maintain a sufficiently long contact time between the sensing mass and the output point tt.

(Means for Solving the Problems) In order to achieve this object, the present invention provides that when the sensing mass is moved forward by inertia force, it comes into contact with the inner surface of the sealed tubular guideway. A protrusion is provided. The protrusion applies a force to the sensing mass that is in contact with the protrusion in a direction that intersects with the direction of movement of the protrusion.

(Function) With this configuration, a motion component in a direction intersecting the direction of movement of the sensing mass is imparted by the protrusion to the sensing mass that moves forward. Therefore, after contacting the protrusion, the kinetic energy component of the sensing mass in the straight direction becomes small, and the forward movement speed is reduced. This also weakens the force with which the sensing mass is bounced back. As a result, the time that the sensing mass is in contact with the output contact becomes sufficiently long.

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

1 to 3 are a horizontal longitudinal sectional view, a vertical longitudinal sectional view, and a vertical lateral sectional view showing one embodiment of the deceleration sensor according to the present invention.

As is clear from these figures, this deceleration sensor 1 has a cylindrical housing 2. This housing 2 includes a cylindrical sleeve 3, a cap 4 which has a larger diameter than the sleeve 3 and seals one end surface of the sleeve, and a case 5 into which the sleeve 3 and cap 4 are fitted and which seals the other end surface of the sleeve 3. It is designed to be installed in the longitudinal direction of the vehicle body, with the cap 4 located at the front in the direction of travel of the vehicle.

Inside the cap 4, a pair of arc-shaped guide surfaces 4a, 4a are provided on the left and right sides, which are connected to the inner circumferential surface 3a of the sleeve 3. , a linearly extending tubular guide path 6 is formed. The front and rear end surfaces of this guide path 6, that is, the left and right end surfaces 7 and 8 in FIG. 1, are both spherical. In this way, the guide path 6 is hermetically sealed from the outside, and the inside thereof is filled with a gas such as an inert gas or air.

A spherical sensing mass 9 having a diameter slightly smaller than the inner diameter of the guideway 6 is housed inside the guideway 6 . The sensing mass 9 is made of a metal with high specific gravity that has magnetism and conductivity. A cylindrical magnet 10 is attached to the rear end surface of the /X housing 2. Therefore, the sensing mass 9 is the first
As shown in the figure, the guide path 6 is normally held in close contact with the rear end surface 8 of the guide path 6 by the magnetic force of the magnet 10.

That is, in this embodiment, the magnet 10 constitutes a holding means for the sensing mass 9.

The guide surface 4a of the cap 4 is slightly longer than the radius of the sensing mass 9. Further, a vertical groove 11 extending to the outer circumference is provided between the left and right guide surfaces 4a, 4a of the cap 4, and the groove 11 is open to the internal space of the sleeve 3. therefore,
When the sensing mass 9 moves close to the front end surface 7 of the guide path 6, the space in front and behind the mass 9 becomes 1 thin 11
They communicate through a relatively large gap.

A pair of terminals 12 and 13 are attached to the bottom surface of the groove 11 of the cap 4 and extend through the front end wall of the housing 2 to the outside. One terminal 12 is connected to a power source such as a battery, and the other terminal 13 is connected to an actuation device such as an air bag. These terminals 12.13
The inner ends of are bent towards the guideway 6, thereby forming a pair of output contacts 14,15. These contacts 14, 15 are made to have sufficient elasticity, and their tips 14a, 15a are positioned in the center of the guide path 6, facing each other with a small interval. . In this way, when the sensing mass 9 moves forward, it is brought into contact with the contact point 14.15 before it comes into contact with the front end face 7 of the guideway 6.

One guide surface 4a of the cap 4 is provided with a through hole 16 penetrating from the outer peripheral surface. And the through hole 1
A bottle 17 is inserted through the hole 6. The inner end of the bottle 17 projects from the guide surface 4a, thereby causing a protrusion 18
is formed. The height of the protrusion 18 is such that when the sensing mass 9 moves forward, the mass 9 comes into contact with the protrusion 18 and the direction of movement thereof can be changed. Further, the position of the protrusion 18 is such that the sensing mass 9 is located at the contact point 14.
．． 15 and then moves further forward while maintaining the contact state, the position is such that the square 9 comes into contact with the square 9. The outer end of the pin 17 is supported by the case 5.

A similar protrusion 20 is also formed on the other guide surface 4a of the cap 4 by a pin 19. The position of the protrusion 20 is further forward than the above-mentioned protrusion 18.

Next, the operation of the deceleration sensor I configured as described above will be explained.

FIG. 4 is an explanatory diagram for explaining the effect.

This deceleration sensor l is arranged so that the cap 4 is located at the front in the direction of travel of the vehicle as described above.

During normal driving, the sensing mass 9 attached to the vehicle body in the longitudinal direction is held in close contact with the rear end surface 8 of the guide path 6 by the magnetic force of the magnet 10 (7).

When a large deceleration occurs in the vehicle body due to a collision or the like, the deceleration is transmitted to the housing 2 of the deceleration sensor 1.

On the other hand, an inertial force is acting on the sensing mass 9 in the direction of movement. As a result, when the deceleration is greater than a predetermined value, the inertial force of the sensing mass 9 becomes greater than the holding force due to the magnetic force of the magnet 10, and the sensing mass 9 begins to move forward. At this time, the mass 9 and the inner peripheral surface 3a of the guide path 6
Since the gap between the two is small, the gas flowing through the gap experiences a large flow resistance. Therefore, the gas is compressed in the space in front of the mass 9, and the pressure in the space behind the mass 9 becomes negative. As a result, the forward movement of mass 9 is damped. Also, since a force is applied to the mass 9 to pull it backward by the magnet 10, this also causes the mass 9 to
The forward motion of is damped.

When the inertial force of mass 9 is greater than these damping forces,
Mass 9 moves forward and contacts contact point 14.15 as shown in FIG. 4(A). Since the mass 9 is electrically conductive, when it comes into contact with the contacts 14.15 in this way, the contacts 14.15 become electrically conductive. therefore,
A current flows from the terminal 12 to the terminal 13, and a signal for operating the first occupant protection device is output.

At this time, more than half of the mass 9 is located within the cap 4. As a result, the gas compressed in the space in front of the mass 9 flows through the groove 11 into the space behind the mass 9 through the large gap between the mass 9 and the mass 9. Therefore, the damping force of the mass 9 due to the gas in the guide path 6 no longer works. Therefore, square 9 moves further forward. During this time, the contacts 14 and 15 are deformed by the mass 9, but the contact between them is maintained.

When the mass 9 moves further forward, the mass 9 moves against the guide surface 4a of the cap 4, as shown in FIG. 4CD).
It comes into contact with a protrusion 18 provided in the. As a result, the mass 9 is given a motion component in a direction intersecting the direction of movement thereof, that is, in the left-right direction. As a result, the mass 9 begins to move in an oblique direction as shown by the arrow in the figure. Then, as shown in FIG. 4(C), it comes into contact with the other protrusion 20. As a result, the mass 9 moves diagonally at a larger angle toward the opposite guide surface 4a, as indicated by the arrow in the figure.

In this way, the square 9 forms the left and right guide surfaces 4a.

It moves forward while reciprocating between 4a.

Therefore, the kinetic energy of the mass 9 is consumed in the movement in the left and right direction, and the forward movement speed decreases. In this state, the mass 9 comes into contact with the front end surface 7 of the guide path 6, as shown in FIG. 4CD).

When the mass 9 comes into contact with the front end surface 7, it is bounced back by the front end surface 7, but since the speed at the time of contact is low, the speed at which it is bounced back is also low.

Moreover, when it is bounced back and moves backward, that square 9
The direction of movement of is again changed by the protrusions 20 and 18, so that the backward movement is damped. Furthermore, just before the mass 9 leaves the contact 14.15, the gap between the mass 9 and the guide path 6 is narrowed, so that the rearward movement of the mass 9 is resisted by the gas in the internal space of the sleeve 3. will begin to receive

In this way, a sufficiently long time is ensured between when the mass 9 contacts and leaves the contact 14.15. During this time, a signal is output from the deceleration sensor 1, so that the occupant protection device etc. can operate reliably. Furthermore, by setting the position of the protrusion 18 that the mass 9 first contacts to be such that the mass 9 contacts the contact point 14.15 after the mass 9 contacts the contact point 14.15, the mass 9 can contact the contact point 14.15.
The time it takes to contact can be set to a short time as set.

FIG. 5 is a horizontal longitudinal sectional view showing another embodiment of the deceleration sensor according to the present invention.

In this embodiment, the guide surface 4a of the cap 4 is curved left and right, and the protrusions 18, 20 are formed by the convex curved surface.
is formed. The rear protrusion 18 is the sensing mass 9 and the contact point 14 .

It is provided at a position where the mass 9 comes into contact when the mass 9 is in contact with the mass 15.

It is obvious that the same effects as those of the embodiments shown in FIGS. 1 to 3 can be obtained with such a deceleration sensor 1.

In the above embodiment, the sensing mass 9 is electrically conductive, but it can also be formed of a non-conductor. In that case, the pair of contacts 14, 15 may be arranged in an overlapping manner.

Furthermore, if the holding means for holding the sensing mass 9 at the initial position is a protrusion or the like that the mass 9 can climb over when the housing 2 is decelerated to a predetermined value or more, the mass 9 can be made of a non-magnetic material. It can also be made to consist of.

Furthermore, in the above embodiment, each guide surface 4 of the cap 4
Although it is assumed that one protrusion 18, 20 is provided on each of the protrusions 18 and 20, more such protrusions may be provided, or conversely, only one protrusion may be provided in total. Moreover, such protrusions 18, 20 can also be provided above and below the guide path 6.

(Effects of the Invention) As is clear from the above description, according to the present invention, the motion component in the direction intersecting the moving sensing mass [J direction] is provided on the inner surface of the guide path for guiding the sensing mass. Since the protrusion is provided, when the sensing mass moves forward, its kinetic energy is consumed by movement in the other direction, and the forward velocity component is reduced. Therefore, the contact time between the sensing mass and the output contact can be increased, and a deceleration sensor that generates a signal over a long period of time can be obtained.

Moreover, since the time it takes for the sensing mass to come into contact with the output contact can be shortened, it is possible to provide a deceleration sensor with excellent responsiveness.

[Brief explanation of drawings]

FIG. 1 is a horizontal longitudinal sectional view showing one embodiment of the deceleration sensor according to the present invention, FIG. 2 is a vertical longitudinal sectional view of the deceleration sensor, and FIG. 3 is a first embodiment of the deceleration sensor. 4(A) to (D) are explanatory diagrams for explaining the action of the deceleration sensor, and FIG. 5 is a vertical cross-sectional view taken along the line m-m in the figure. It is a horizontal longitudinal cross-sectional view which shows another Example. 1... Deceleration sensor 2... Housing 6...
・Guidance path 9...Sensing mass 10...
・Magnet (holding means) 14.15...Output contact 18.20...Protrusion Figure 1 Figure 3 (C) Mu CD)

Claims (2)

[Claims] (1) Housing 2 having a sealed tubular guideway 6
is accommodated in the guide path 6, and is normally held at the rear end of the guide path 6 by the holding means 10, and when the housing 2 is decelerated to a predetermined value or more, the guide path 6 a sensing mass 9 that moves toward its front end along the guide path 6; and output contacts 14, 1 that are provided at the front end of the guide path 6 and are closed when the sensing mass 9 comes into contact with the sensing mass 9.
5, and: When the sensing mass 9 moves against the inner surface of the guide path 6, the sensing mass 9 comes into contact with the inner surface of the guide path 6, so that the motion component in the direction intersecting the moving direction is A deceleration sensor including a protrusion 18 attached to a sensing mass 9. (2) The protrusion 18 causes the sensing mass 9 to move and the output contacts 14 and 1 to
The deceleration sensor according to claim 1, wherein the deceleration sensor is provided at a position where the sensing mass 9 comes into contact with the deceleration mass 9 after the deceleration sensor reaches a state where the deceleration mass 9 comes into contact with the deceleration mass 9 .