FR2559582A1 - LOW ACCELERATION THRESHOLD SAFETY DETECTOR FOR A MOTOR VEHICLE HABITACLE - Google Patents

Abstract

THE INVENTION RELATES TO AN ACCELERATION OR VARIATION OF SPEED DETECTOR, PART OF AN INFLATABLE BAG TYPE SAFETY SYSTEM IN A VEHICLE. THE DETECTOR 38 INCLUDES AT LEAST ONE MOBILE WEIGHT 41 WHOSE MOVEMENT UNDER THE EFFECT OF ACCELERATION CAUSES THE RELEASE OF A FIRE PIN FROM A PRIMER OR A DETONATOR 36 RELEASING THE INFLATION OF A BAG OF SAFETY, AS SOON AS THE ACCELERATION OF THE INTERIOR IS OF THE ORDER OF 4G. THE INVENTION APPLIES IN PARTICULAR TO SECURITY SYSTEMS FOR MOTOR VEHICLES.

Description

Safety sensor with low acceleration threshold

  for a passenger compartment of a motor vehicle.

  The invention relates to a low security detector

  acceleration threshold, intended to be mounted in the

  tackle a motor vehicle and can be action-

  born without electrical energy, particularly for inflating a safety bag. It has been found that in a frontal impact at approximately km / h on a fixed obstacle, a restraint such as an airbag or airbag must begin to

  remember the driver when it moved

  about 12 or 13 centimeters forward, to avoid injury. The inflation mechanisms of

  bags require a certain period of time,

  30 milliseconds, to inflate the

  bag from the transmission of a trigger signal

inflation by a detector.

  It has also been found that a protective device for a passenger is necessary during accidents in

  which the movement of the passenger in relation to the vehicle

  It reaches a speed of about 20 km / h or more.

  It is therefore necessary to have a detector which will determine that the passenger will hit a part of the interior of the vehicle at a speed of approximately 20 km / h or more and which, for a frontal impact at approximately km / hr. h on an obstacle, will trigger inflation of the bag, for example 30 milliseconds before the passenger

  moved forward 12 or 13 centimeters.

  It is important that the detector that triggers the

  operation of the inflation means of the bag is sen-

  the acceleration of the passenger compartment of the vehicle

  t8t than that of certain other parts of the vehicle,

  because this location of the detector produces some advan-

  compared to other locations. For example,

  if the front bumper of the vehicle comes into contact with a

  water or the like that breaks at the moment of impact or shortly after the impact, a detector mounted on the front bumper may experience a change in speed

  approximately 20 km / h or more before the failure of the

  while the passenger compartment of the vehicle may be

  put to a negligible speed variation. Under these circumstances, inflation of the bag is not necessary, and if it occurs, it may even contribute to an accident.

  ulterior. It is therefore important that the detection (s)

  vehicles equipped with the vehicle are mounted in such positions and have a construction such that they can predict that the passenger compartment will experience a speed change requiring protection of the passenger. Mechanical type shock detectors (relative to

  detectors of the electronic type) which have been

  mass-produced detectors are

  The terms "spring mass" or "non-damped mass

  "spring loaded" which are used here relate to the detec-

  in which the movement of a mass of

  tion is controlled solely by the acceleration applied

  to the detector, by its inertia in translation or in rotation and by a restoring force such as that produced by a spring, a magnet or a belt of the "rolamite" type. The spring-loaded sensor is known to function properly for

  shock pulses having a short duration. These impulses

  are characteristic of the onset of shocks or erratic

  standards on obstacles. When the vehicle on which the detector is mounted undergoes a deceleration pulse greater than the restoring force on the detection mass, such as that which would accompany a shock or crash, the detection mass moves

  quickly to the front end of the vehicle and

to inflate the bag.

  ZO As a reference, it is indicated that the acceleration

  ximal pressure due to the braking of the vehicle is of the order of

0.7 g.

  Systems already proposed include detectors

  shocks that are mounted outside the crash zone.

  ment. So far, all these detectors have

  acceleration thresholds that are greater than about 7 g.

  All of these known detectors are in fact threshold detectors rather than velocity detectors. In the event of a shock or crash in

  which a vehicle traveling at 50 km / h hits an object

  jet causing a constant acceleration that is slightly less than 7 g, which could occur

  when the vehicle comes into contact with an ignition

  which is currently often placed around many rigid structures on the sides

  of a road, the occupant of the vehicle may be injured

  serious or fatal. This is definitely

  accident requiring the bag to be inflated, and yet

  However, no known mechanical detector would have

  latch. Other situations where mechanical detectors

  known are in default, are impacts on snow banks, arrivals on: flooded areas of

  road, or-impacts on soft ground.

  In addition, some of the known detectors, which are

  inside the vehicle, can not make

  distinctions between a real condition of shock

  the inflation of a safety bag and the conditions

  This does not require inflation, for example in the event of an impact at the rear of the vehicle, movement on a curve, on a railway line or when passing over a hole in the road. Known detectors

  inside the passenger compartment, which have acceleration thresholds

  are very sensitive to the very short pulses normally encountered in such conditions and cause the bag to be inflated when this is not

not necessary.

  The subject of the invention is a detector mounted in the housing

  bitacle of a vehicle, to avoid problems

  encountered in the detectors of the prior art when

  they are located outside the crush zone

  and, in particular, in the passenger compartment of the vehicle.

  The invention also relates to a detector mounted in the passenger compartment of the vehicle, which is of the low threshold type of acceleration and which is sensitive to variations

  of. speeds that require acceleration to be maintained

  naked below the recall threshold for a period

prolonged time.

  The invention proposes for this purpose a low detector

  acceleration threshold, intended to be mounted in the

  motor vehicle, characterized in that it can operate without electrical energy to actuate a pyrotechnic device, this detector comprising a

  movable mass of detection, a rotating shaft, a trin-

  detection system which includes means for trans-

  to form the movement of the rotating detection mass

  the shaft, a primer, a firing pin biased by a spring and operatively connected to the shaft to be held in a retracted position, relatively low acceleration threshold return means acting on the mass of detection, and means forcing the detection mass to move on a

  predetermined distance before the rotation of the

  is sufficient to allow the pin to

  on fire to be released and come knocking the primer.

  The invention also proposes a mass detector to

  spring, of the mechanical type, placed in a zone of non-

  to be used with a security system

  airbag system, characterized in that it comprises a detection mass sensitive to acceleration,

  return means which are such that the mass of detection

  tion moves against the action of the biasing means for accelerations greater than a predetermined value which is less than 7 g, firing means responsive to a predetermined movement of the sensing mass, and a primer intended to be put

  by the aforementioned means and which triggers the

fúlage of the aforementioned bag.

  The invention also proposes a detector mounted in

  the passenger compartment of a vehicle, characterized in that

  takes low-speed booster means

  for the detector, means making the sensor responsive to a change in speed, and means requiring sustained acceleration above the acceleration threshold of the biasing means for a period of time.

extended time.

  In the following description, given as an example,

  Referring to the accompanying drawings, in which: - Figure 1 shows schematically a part of a

  interior of a motor vehicle, including systems

  air bag security systems provided with detectors according to the invention;

  FIG. 2 is an exploded perspective view of the system

  airbag system, some parts of which are

feeling partially wrenched;

  FIG. 3 is a side view in elevation of the detection

  and a gas generator, shown broken away, and a tip extending from a steering wheel nut used to permit operation of the detector when mounted in place;

  FIG. 4 is an enlarged partial view representing

  both the end of the rotary shaft and the mounting plate supporting this shaft; FIG. 5 is a plan view of the sensor whose

  cover is removed and other parts are

  presented in partial tear-off, this figure represents

  sensing the armed detector and the representative pointing

  when in a safe or inoperative position;

  FIG. 6 is an enlarged partial view of the detection

  a driver representing the moving mass and the associated pin extending from the rotary shaft, prior to movement of the mass caused by a collision; FIG. 7 is a view similar to FIG. 6, representing the mass displaced as a result of a shock

  or a collision and the movement of the spindle

attached to the rotating shaft;

  FIG. 8 is an enlarged partial view of the

  firing pin held in retracted position by the rotating shaft;

  FIG. 9 is a view similar to FIG.

  having the firing pin released as a result of an impact or collision; FIG. 10 is a view similar to FIG. 6, but represents another embodiment of the invention, comprising a spring-mass detector

not damped.

  In the drawings, there are shown security systems

  8 and 8 'of the air bag retaining type, which comprise the detector according to the invention and which are mounted inside the passenger compartment of a vehicle,

  driver's side and passenger's side. The detector-

  trigger 10 is preferably mounted inside

  of the gas generator or inflator 12. However, this -

  trigger-sensor can be mounted in another way,

  while still being located in the cockpit. The gonad

  flower 12 is mounted symmetrically on a frame

  14 on which is also mounted the boot or cover

  key 16 of the bag 18 in the folded state. A diffuser plate 20 is interposed between the inflator and the air bag and

  is also attached to the frame 14.

  The security system 8 according to the invention is mounted on the steering wheel 22 of the. vehicle through

  The steering wheel 22

  takes a peripheral ring 24 and a suitable number of radial branches 28. the security system 8 'is mounted appropriately on the passenger side in

  the cockpit and can include two sets of embarrassment.

  gas detectors and detectors that may have the same

  me sensitivity to shocks or different sensitivities.

  The gas generator 12 comprises a housing 32 containing a gas production material 34 which may be sodium nitride. Sodium nitride is stable over a wide range of temperatures, but when it is ignited, it decomposes rapidly, releasing a very

large volume of nitrogen gas.

  Reference is now made to FIGS.

  feeling in detail the trigger-detector 10. To improve

  improve reliability and safety, two detectors

  tis 38 are intended, redundantly ,. to actuate respective primers or detonators 36 contained in the casing 40. Each detector 38 comprises a damped detection mass 41 that can move in a limited manner inside the cylinder 39 of the block 44 contained in the casing 40. Before the system 8 is mounted on the steering wheel 22, the movement of the detection mass 41 in the cylinder 39 is

  prevented by means which are described below.

  When the system is mounted on the steering wheel

  an extension or tip 48 which is formed on the nut 50 which holds the steering wheel on

  the steering column, enters the hole of

  cage 51 provided in the detector 10. The tip 48 moves

  this is a conical lock pin 54, allowing detection mass locking arms 52 to turn and move apart from the path of the sensing masses.

  51, so as to arm the system. The arms of

  cage 52 have a common connection and are subject to

  springs55 pushing the arms towards each other

  the other. The arms are kept apart and therefore in

  tact with the detection masses 41 to prevent their movement, thanks to the conical shape of the pin

  54. When the detectors are rendered inoperative

  perished or in a safe position, the part of

  larger diameter of the taper pin 54 is

  between the arms 52 so as to maintain these

  the pin 54 is moved inwardly, the small-diameter portion of this pin is opposite the arms which, under the the action of the springs 55, are moved towards each other so as to release the detection masses 41. As explained above, the movement

  towards the inside of the taper pin 54 is provi-

  the tip 48 of the steering wheel nut 50

tion.

  Each detection mass 41 is associated with a pin 56 which extends from a D-shaped shaft 58 or

  flat shaft. The other end of pin 56 is

  takes a spherical ball 60 bearing on a return spring 62 to ensure the contact of the pin 56 with the corresponding detection mass 41. Each shaft 58 comprises a flat face or a flat surface 64 formed in a substantially cylindrical outer surface. Of

  plus, a firing pin 66, associated with a resistor

  reminder spell, is aligned with a leader or detonator

  36 and is held in a retracted position by the cylindrical portion of the shaft 58, and is released

  when aligned with the flat face 64 of the

  58. In the case where the motor vehicle undergoes an impact or collision, each detection mass 41 moves to the right as shown in FIG. 7. However, a resistance to this movement is created by the return spring 62 acting on the detection mass via the pin 56 and by the difference in air pressure between the left side and the right side of the detection mass 41. This air pressure is gradually canceled by passage of the air in the

  clearance between the detection mass 41 and the cylinder 39.

  If the shock is large enough, the mass 41 will move sufficiently to the right to bring

  the shaft 58 to turn sufficiently to release the gou-

  Pille 66 firing and allow it to move beyond the flat 64 and come to strike the primer 36 which is then fired to trigger the firing or burning of cords or co-operating wicks to trigger the combustion of the gas-producing material 34 which itself causes the

inflating the security bag.

  FIG. 10 shows an example of a detector

  38 'with spring mass, which comprises a mass of detection

  41 'substantially undamped. In all its other aspects, the 4th triggering detector 10 'is similar to the

  trigger-detector 10 of FIGS. 3 to 9, and the same

  my references are used with the premium index for

  designate the corresponding elements of this detector.

  1 1 For all detectors according to the invention, whether of the damped type or not, thresholds are provided

  relatively low acceleration rates, which are

  around 4 g and below 6 or 7 g, because of the location of these detectors in the

  tackle the vehicle. In addition, detectors according to

  These are velocity change detectors in the sense that they require a relatively large velocity change to take place after the acceleration threshold is exceeded, which requires that acceleration be maintained above the threshold.

  for a relatively long period of time.

  Normally, this period of time ranges from 15 to 100 million

  lisonds as a function of the amplitude of the acceleration.

  In this way, we reduce the number of cases where the bag

  is inflated when this is not necessary.

  to inflate the bag when necessary in the case where the shock impulses

  long and slow acceleration type, for example

  as a consequence of a shock or collision with

  shock absorbing means.

  When the planned security system on the passenger side

  ger includes two trigger detectors, sensiti-

  the detectors may be different, or it may be possible to use pyrotechnic delay means

  associated with one of the detectors to produce a function

  Step-by-step safety bag inflator. This stepped operation is useful for avoiding or minimizing injuries to passengers

out of position.

  The term "acceleration" used here means accelerating

  vehicle in the opposite direction to that which would occur in a collision where the speed of the

  vehicle is reduced or when. vehicle in station-

  hitting the front and accelerating

oriented towards the back.

  The primers or detonators used in the invention

  may be constituted by pyrotechnic devices

  of any type, for example by

  such impactors, impact detonators or primers to

electric tripping.

Claims (13)

Claims.   1. A detector with a low threshold of acceleration, intended to be mounted in the passenger compartment of a motor vehicle, characterized in that it can operate without electrical energy to actuate a pyrotechnic device and in that it comprises a mass mobile detection   (41), a rotary shaft (48), a detecting linkage   comprising means (56) for transforming the movement of the sensing mass (41) into rotation of   the shaft (58), a primer or detonator (36), a shaft   firing pin (66) associated with a feedback spring   pel and operably connected to the shaft (58) to be held in a retracted position, means   relatively low acceleration threshold (62)   ble acting on the sensing mass, and means forcing the sensing mass to move a predetermined distance before the shaft (58) has rotated sufficiently to release the firing pin (66) which comes to strike the primer (36).   2. Detector according to claim 1, characterized in that means (52, 54, 55) are provided for blocking   the detection mass (41) and make the sensor   before mounting on the vehicle.   3. Detector according to claim 1, characterized in that it comprises means (14) for mounting in the interior of a vehicle.   4. Detector according to claim 1, characterized in that the detection mass (41) can move from   limited way in a cavity (39.) and in that the   yens of return are constituted by a spring (62).   5. Detector according to claim 4, characterized in that the movement of the detection mass (41) is damped. 6. Detector according to claim 1, characterized in that the linkage comprises a spindle (56) extending   radially from the shaft (58) and which is   born to come into contact with the detection mass (41).   7. Detector according to claim 6, characterized in that the pin comprises two diametrically opposite parts relative to the shaft (58) and in that the return means comprise a return spring (62).   and means (60) at the end of the pin (56)   when in contact with the spring (62) to push the spindle   (56) on the detection mass (41).   8. Detector according to claim 1, characterized in that the shaft (58) comprises a flat (64) allowing   to release the firing pin (66) when the   (58) rotated from a predetermined amount to the   following the movement of the detection mass (41).   9. Detector according to claim 1, characterized in that two detectors are associated with two primers (36) to form a redundant detection system   actuating a safety bag inflator.   10. Detector according to claim 1, characterized in that the acceleration threshold of the return means not more than 6 g.   11. Detector according to claim 10, characterized in that the acceleration threshold of the return means is about 4 g.   12. Spring-loaded mass detector, of the mechanical type,   in a non-crush zone and associated with an air bag type safety system, characterized   in that it comprises a sensing mass (41) sensi-   acceleration means, return means (62) which are   such that the detection mass (41) moves to the   against the action of the means of recall for   greater than a predetermined value which   is less than 7 g, means (66) of firing sen-   to a predetermined movement of the mass of   (41), and a primer to be fired   by the aforementioned means (66) and which triggers the flage of the aforementioned bag.   13. A security detector mounted in the passenger compartment of a vehicle, characterized in that it comprises low acceleration threshold return means for the detector, means making this detector sensitive to a variation in speed, and means by which acceleration must be maintained above the aforementioned threshold for an extended period of time.