CA2180986C - Mechanical crash sensor - Google Patents

Abstract

A crash sensor for a motor vehicle comprising: a housing defining a path of movement between a first and a second position; a mass disposed in said housing for movement along said path; biasing means for biasing said mass toward said first position;
crash indication means for indicating a crash when said mass is at said second positions;
blocking means for blocking said crash indication means, said blocking means including a blocking element movable between an armed and a disarmed position; and arming means for automatically arming said sensor by deactivating said blocking means, said arming means including an arming member detached from said housing and attached to said motor vehicle and a rotatable member extending into said housing for selectively moving said blocking member between said armed and disarmed positions when said housing is installed in the motor vehicle.

Description

,4~180986 TITLE OF THE INVENTION

CRASH SENSOR FOR MOTOR VEHICLES

The present application is a divisional of CAn~ n Patent Application Serial No. 2,071,057 filed June 11, 1992.

S BACKGROUND OF THE INVENTION

A. Field of Invention This invention pertains to a sensor used for triggering passenger restraint system in a motor vehicle such as an air bag system, and more particularly to a self-contained mechanical sensor with ~ rming means whereby the sensor can be set off only 10 when it is installed within a passenger restraint system.

B. Description of the Prior Art Sensors for passenger restraint systems are used to detect passenger restraint systems for detecting a crash. These sensors must be able to discrimin~te between sudden changes in the velocity of a motor vehicle due to normal operations, and abrupt velocity 15 changes which may result in injury to the passengers. These sensors are often placed in the crush zone of the vehicle because in this zone it is easier to discrimin~te between acceptable and dangerous velocity changes. However inherently such sensors are less reliable because they must be coupled electrically or mechanically with the rest of the restraint system. Several sensors have been suggested which are made physically integral with the passenger restraint system. In this manner the need for long electrical or mechanical coupling means is eliminated. However, until now, all these systems were complicated to make.
For example, U. S. Patent No. 4,167,276 discloses a sensor relying on a rolamite ball arrange-ment to sense a crash. The patent also discloses a complicated automatic interlock coupled to the rolamite ball arrangement.
Commonly assigned U. S. Patent No. 4,666,182 discloses an all mechanical sensor with multiple inertial masses for the sake of redundance.
OBJECTIVES OF ASPECTS OF AND SUMMARY OF THE INVENTION
An objective of an aspect of the present invention is to provide a mechanical crash sensor which is relatively uncomplicated so that it is easy and inexpensive to make.
An objective of an aspect of the invention is to provide a sensor with external adjusting means which allows for the adjustment of the sensor sensitivity.
An objective of an aspect of the invention is to provide a small sensor with redundancy to insure a proper operation. Other objectives and advantages of the invention shall become apparent from the follow-ing description.
The crash sensor constructed in accordance with this invention comprises a housing defining a path of movement between a first and second position with a mass disposed in the housing for movement along the path. Biasing means are provided for - 21g~9~

biasing the mass toward the first position. Crash indication means are provided for indicating a crash when the mass is at the second position. Locking means are provided to block the crash indication means. The blocking means include a blocking element movable between an armed and disarmed position, and arming means for automatically arming the 5 sensor by deactivating the blocking means. The arming means includes an arming member detached from the housing and attached to the motor vehicle and a rotatable member extending into the housing for selectively moving the blocking member between the armed and disarmed positions when the housing is installed in a motor vehicle.

BRIEF DESCRIPIION OF THE DRAWINGS

These and other advantages of the invention will become apparent upon reading the following detailed description and upon referring to the drawings in which:-Figure 1 shows a side view of a sensor constructed in accordance with this invention, as it is being installed in a passenger restraint system;
Figure 2 shows an end view of the sensor of Figure l;
Figure 3 shows a side sectional view taken along line 3-3 in Figure 2;
Figure 4 shows a side sectional view taken along line 4-4 in Figure 2;
Figure 5 shows a cross-sectional view taken along line 5-5 in Figure l; and Figure 6 shows a cross-sectional view taken along line 6-6 in Figure 1.
While the invention will be described in conjunction with an example 20 embodiment, it will be understood that it is not intended to limit the invention to such embodiment. On the contrary, it is intended to cover all alternatives, modifications and ~ 1 80~6 equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description, similar features in the drawings have been given 5 similar reference numerals.
Referring now to the Figures, a sensor 10 constructed in accordance with this invention includes a generally tubular wall 12 termin~ed with a cap 13. Cap 13 has an extension 14 at one end. The other end 15 of the wall 12 is closed. Extension 14 rotatably holds a cylindrical insert 16 having a D-shaped hole 18. Insert 16 is captured by a C-shaped washer 20 (shown in Figure 3). An O-ring 22 is disposed inside extension 14 to seal the interior of the sensor 10. A portion of the cap 13 is indented to define with wall 12 a finger 24 as seen in Figures 2 and 3.
Inside sensor 10, a tubular space 26 is formed with internal threads 28 extending from end 15. A threaded screw 30 is disposed in space 26 at the end adjacent to wall end 15. An O-ring 32 seals the space 26 from ambient atmosphere. The screw 30 has an internal spherical wall 34. Also in space 26 is a metallic sleeve 36. The sleeve 36 is floating with respect to wall 12 and is m~int~ined in position by a resilient ring 38. Within sleeve 36 there is an inertial mass in the form of a ball 40. Ball 40 is biased against surface 34 as described below. The diameter of the ball is subst~nti~lly equal to the diameter of 20 sleeve 36 so that as the ball moves through the seal, its motion is damped by the air within the sleeve. Opposite to surface 34, cap 13 is formed a spherical surface as at 42 to form a 2~80986 stop for ball 40. Thus a linear path is formed for ball 40 from surface 34 to surface 42.
This path is parallel with, but offset from the longitudinal axis 44 or sensor 10.
A trigger or triggering device, illustrated in Figure 3 as lever 46, is mounted on a shaft 48 inside the sensor 10. The lever has two opposed arms 50, 52. Mounted on end 15 there is a toroidal compressing spring 54 with a cap 56. Cap 56 is pushed by spring 54 to urge arm 50 to the left, as seen in Figure 3. As a result of this biasing force, opposite arm 54 pushes ball 40 to the right, against wall 34, as shown in Figure 3.
As shown in Figure 4, also mounted on end 15, there is another compression spring 60 termin~ting in a cap 62 with a spike 64. Opposite cap 62, cap 13 holds a primer charge 66. Cap 62 has a flange. Importantly, adjacent to cap 62, shaft 48 is formed with a D-shaped disk 70 with a flat surface 72.
The sensor is provided with another compression spring (not shown) termin~ted in a cap 74, D-shaped disk 76 and primer charge 80 on the other side of lever 46.
The ends of shaft 48 are mounted in journals 82, 84 which allow the shaft 48 to pivot. As a result, when the sensor is armed, arm 52 may pivot from a first position shown in Figure 3 wherein it pushes ball 40 against wall 34 to a second position shown in Figure 4 wherein ball 40 is in contact with wall 42. In this second position, arm 52 is disposed in a cavity 85 formed in cap 13 as follows.
As shown in Figure 5, cap 13 is provided with a central hole 86 for holding insert 16. The bottom surface 88 of insert 16 is provided with a rectangular cut 90 having a width slightly greater than the width of lever arm 46. Preferably, as seen, in Figure 5, cut 90 has two levels 92, 94 separated by a wall 96. Insert 16 is also provided with an extension 98 extending radially and tern in~ting in a tangential arm 100. Cap 13 also has a arcuate cut 218~986 102 holding a compression coil spring 104. Spring 104 is held in cut 102 by a plate 106.
One end 108 of spring 104 is in contact with arm 100 of extension 98 as shown. Cap 13 is also formed with a cut 110 having a width equal to the width of cut 90. Cut 90 is made so that it extends through surface 42.
S As previously mentioned, insert 16 is rotatable within cap 13. When the sensor is not installed in place, spring 104 pushes extension 98 clockwise to the position shown in Figure 5. In this position cut 92 is angularly displaced from cut 110. As a result, as shown in Figure 3, surface 8B acts as a stop which does not permit arm 52 to move into cavity 85. Thus even if the sensor 10 is accidentally activated, for example by dropping it, or hitting it with a hammer, the sensor will not go off, as explained more fully below.
Once the sensor is assembled, it is ready to be installed in a passenger restraint system. This system 120, a partial view of which is shown in Figure 1, includes a cavity 122 constructed and arranged to hold sensor 10. More specifically, cavity 122 includes a rod 124 extending from the floor 126. Rod 124 has a D-shaped cross-section for matching the hole 18 in insert 16. On one side, cavity 122 is also provided with a hole 128 to hold finger 24 (shown in Figure 3). Thus hole 128 and finger 24 cooperate to form a detent or indexing means for the sensor. Sensor 10 is installed by first positioning and mounting it over shaft 124. In this position, the sensor is still unarmed, i.e. arm 98 is in position shown in solid lines in Figure 5. In this position, the finger 24 is not aligned with hole 128 and therefore the sensor cannot be seated into cavity 120. In order to complete the in~t~ ion, the sensor is turned to bring the finger 24 in alignment with hole 128 and then the sensor is pushed in so that it is fully seated. Importantly, while the sensor 10 is rotated with respect to the fixed shaft 124, since the shaft 124 is coupled to insert 16, the insert also remains fixed. As a result, the sensor together with the cap 13 rotates with respect to the insert 16 until arm 98 reaches the position 98' shown in dotted lines in Figure 5. In this position, cut 90 is also rotated to position 90' in which it is aligned with cut 110. Therefore once the sensor is seated within the passenger restraint system 120, cut 92 is shifted angularly to complete cavity 85. In this configuration, the lever is free to move fully to the second position shown in Figure 4. In this position the sensor is fully armed.
Once the sensor 10 is installed and armed as described above, it is ready for operation. During normal operation of the motor vehicle, ball 40 is biased against wall 34 by lever 50. In this position, the D-shaped disks 70, 76 keep the caps 62 and 74 in the position shown in Figure 4. When the vehicle is involved in a crash resulting in a large velocity change, the ball 40 is subjected to a force large enough to overcome the biasing of spring 54. The exact speed change at which the ball starts moving may be adjusted by ch~nging the position of screw 30. In response to this force, ball 40 moves from the first position shown in Figure 3 to the second position shown in Figure 4 and pivots lever 50 counterclockwise. As a result of this pivoting motion, the D-shaped disks 70, 76 rotate in a position which allow the caps 62, 74 to move towards cap 13. Because of the force generated by spring 60 (and the spring not shown but coupled to cap 74) caps 62, 74 then hit the primer capsules 66, 80. As a result the primer capsules are set off and ignite the gas generator compound 130 in the passenger restraint system.
Obviously numerous modifications may be made to this invention without departing from its scope as defined in the appended claims.

Claims (6)

1. A crash sensor for a motor vehicle comprising:
a housing defining a path of movement between a first and a second position;
a mass disposed in said housing for movement along said path;
biasing means for biasing said mass toward said first position;
crash indication means for indicating a crash when said mass is at said second positions;
blocking means for blocking said crash indication means;
said blocking means including a blocking element movable between an armed and a disarmed position; and arming means for automatically arming said sensor by deactivating said blocking means, said arming means including an arming member detached from said housing and attached to said motor vehicle and a rotatable member extending into said housing for selectively moving said blocking member between said armed and disarmed positions when said housing is installed in the motor vehicle.

2. The crash sensor of claim 1 wherein said blocking means further comprises a blocking spring for urging said blocking member toward said armed position.

3. The crash sensor of claim 1 wherein said blocking member is rotatable between said armed and disarmed positions along an axis parallel to said path.

4. The crash sensor of claim 1 wherein said rotatable member is a cylindrical insert.

5. The crash sensor of claim 4 wherein said insert has a central hole for receiving said arming member.

6. The crash sensor of claim 5 wherein said hole and said arming member have complementary cross-sections.