Sensor arrangement triggerable by deceleration forces

A sensor arrangement which is adapted to be triggered by deceleration forces. The sensor arrangement forms a component of a vehicle safety belt system and includes a mass deflectable from an initial position to a deflected position upon exceeding a predetermined deceleration and an indicator which responds if the belt of the safety belt system has been deployed during the occurrence of the predetermined deceleration. The mass is associated with the indicator and has such a mounting and/or includes a track of such an ascending slope, that the full deflection of the mass is attained only beginning at a deceleration of about 2 g. An arrangement is provided for preventing the deflected mass from returning to the initial position.

The present invention relates to a sensor arrangement and, more 
particularly, to a sensor forming a part of a safety belt system for motor 
vehicles, with the sensor being adapted to be triggered by deceleration 
forces and including a mass which may be deflected or displaced upon 
exceeding a predetermined deceleration and an indicator means which 
responds if the belt of the belt system is worn at a time of occurrence of 
the predetermined deceleration. 
A known prior device includes an arrangement wherein a mass responds at a 
deceleration of about 0.7 g and thereby blocks a reel of a belt roll-up 
means of a safety belt system. In this device, a shaft accommodating the 
reel of the belt roll-up means includes a deformable central zone of a 
bearing flange so that, in case of a relatively high tensile load on the 
belt strap of the belt system, the belt strap is blocked in an extracted 
position occupied at that given point in time. The blocking of the belt 
strap already takes place at a belt load lying markedly below a limit or 
critical load so that the belt, with a corresponding reduction in comfort, 
can still be utilized. 
Since it is possible to reach a response or threshhold value of the inner 
mass of about 0.7 g by, for example, a sharp braking action of the motor 
vehicle, it is thus also possible, in a relatively simple manner, to 
subsequently apply a load to the belt of the safety belt system, of the 
above-noted device, while retaining the roller blocking effect which 
occurs during the sharp braking, with this subsequent load leading to a 
deformation of the bearing flanges and thus to a blockage of the belt 
strap. Previously, there has been no indication of interest with a high 
degree of proof, for, for example, by experts such as medical examiners 
and insurance companies, a determination of the fact as to whether a 
safety belt had actually been applied during an occassion of a collison of 
the motor vehicle. 
The aim underlying the present invention essentially resides in providing 
an indicator arrangement cooperable with a sensor triggerable by 
deceleration forces. The indicator may be manipulated only when a 
relatively high predetermined amount of force has triggered the indicator, 
thereby permitting the assumption with a high degree of probability that 
the safety belt was worn or deployed during a preceding collison of the 
motor vehicle. 
In accordance with advantageous features of the present invention, a sensor 
arrangement is provided which constitutes a component of the safety belt 
system and includes a mass which is deflectable upon exceeding a 
predetermined deceleration. An indicator is provided which responds if the 
belt is deployed during an occurrence of deceleration which is at or 
exceeds the predetermined rate. The inert mass associated with the 
indicator has such a mounting, and/or a track of such an ascending slope, 
that the full deflection is attained only starting with a deceleration of 
about 2 g, and means are provided for preventing the deflected mass from 
returning to its initial position. 
By virtue of the above-noted features of the present invention, such a high 
deceleration force is required, which forces cannot be obtained by a 
braking maneuver, so that only experts with an in-depth knowledge of the 
device would be capable of conducting a corresponding manipulation without 
damage. 
Advantageously, in accordance with the present invention, the inert mass 
may be fashioned as a rolling body such as, for example, a ball and, 
advantageously, the indicator may represent an electrical or electronic 
component to which is transmitted, during a deflection of the inert mass, 
permanent information which may then subsequently read off or read out 
therefrom. 
Advantageously, in accordance with further features of the present 
invention, the inert mass may be biased by a spring connected to an 
electrical wire wherein contact takes place through the spring when the 
mass is deflected into electrical connection with prepositioned 
toroidal-shaped contact thereby causing a grounded fuse to melt if the 
inserted latch tongue closes a contact arranged in the lock housing of the 
safety belt system. 
A simple mechanical structure which can be quickly tested includes an inner 
mass accommodated in a tubular element arranged between a belt mounting 
point and a cover plate receiving the belt strip, the tubular element 
adapted to be permanently deformed by belt forces introduced into the 
mounting point while retaining a position of the deflected mass. 
Advantageously, in accordance with further features of the present 
invention, the inert mass may be a liquid with the tubular element being 
provided with sealing lips along an inner wall thereof, which sealing lips 
prevent a back flow of an externally visible liquid when the tubular 
element has been subjected to a compressed condition. 
To provide an easy readability of the indication that the seat belt was 
worn during the occurrence of a collision, with a ball being arranged as 
the inert mass, the ball is adapted to leave an externally visible 
impression during a deformation of the tubular element. 
In accordance with still further features of the present invention, 
especially useful in a static belt system, the inert mass may be located 
in a lock housing and a latch tongue insertable in the lock housing 
providing a prerequisite for a possible subsequent response of the 
indicator. Advantageously, the inert mass may be in the form of a ball 
located in a depression trough or indentation provided on a base of the 
belt lock, with the belt lock accommodating the latch tongue through the 
interposition of a spring loaded ejector. In this connection, a bottom 
part of the spring loaded ejector, facing the depression trough or 
indentation prevents the ball from jumping out of its position when the 
latch tongue is inserted; whereas, if the ball has jumped or has been 
displaced out of position due to a deceleration, the spring loaded ejector 
will abut against the ball before locking of the latch tongue has taken 
place in case of an attempt of a subsequent introduction of the latch 
tongue. 
It is also possible, in accordance with the present invention, with a 
static belt system for an inert mass in the form of a ball to be arranged 
in a depression located in a path of a sloping plane, with the depression 
being arranged at an upper end of a holder supported at the lock housing 
by way of a spring. Upon the occurrence of a predetermined decelaration 
the ball will roll to the deepest point of the sloping plane only after a 
preceding compression of the spring and then prevents, upon a reduction in 
belt force, a return of the holder into its initial condition due to the 
supporting effect with respect to the lock housing. By virtue of this 
arrangement, it can readily be ascertained whether the belt has been 
deployed and the sensor triggered. 
According to the present invention, a lever may be provided which is 
pivotably supported in the lock housing, and is under a bias of a spring, 
with one arm of the lever resting on the holder and the other arm of the 
lever abutting, in case of a downwardly oriented movement of the holder, 
against an ejector cooperating with the latch tongue, if the latch tongue 
is in engagement but which will pivot past the ejector if the latch tongue 
has not been engaged or inserted. 
With a sensor having a belt retractor receiving a free end of the belt 
strap, a simple construction is possible according to the present 
invention by virtue of an inert mass arranged in front of the belt roll-up 
or retractor means, which when further extraction of the belt, taking 
place during the occurrence of a collision of the motor vehicle, is 
utilized for triggering the indicator. Advantageously, the inert mass may 
be fashioned as a pendulum which, upon its deflection, pivots an angle or 
elbow lever having a free end which dips into a guide means having a 
wedge-like extending guide slot and being traversed by the belt strap, 
wherein with full deflection of the pendulum the belt strap is blocked by 
the jamming free end of the angle lever. 
In order to provide for an extremely compact construction wherein a belt 
retractor is used which receives a free end of the belt strap of the 
safety belt system and having a locking device arresting the belt reel in 
case of a predetermined dangerous deceleration, it is advantageous if an 
unreeling or unwinding of a strap length provides the precondition for a 
possible subsequent response of the indicator. In this connection, it is 
suitable to arrange the inert mass so that it rests in a depression during 
normal driving operation and is maintained under a bias of a spring, with 
a lever acting on the inert mass, which lever is equipped with a detent 
tooth. The detent tooth, after a blocking device arrests the reel 
response, then engages a toothed rim associated with the reel once a 
feeler or sensor, scanning a coil diameter of the wound up belt strap, has 
released the lever and the mass lifts from a bottom of the depression due 
to the effect of centrifugal forces. 
In order to preclude a further use of the sensor arrangement of the present 
invention once the same has been deployed, advantageously, the detent 
tooth may be supported in the manner of a ratchet so that it can be 
pivoted away in a belt retraction direction so that when the belt is 
automatically rolled up it can no longer be extracted. 
In order to render manipulation of the sensor arrangement difficult or 
recognizable, the lever may be equipped with an extension which, when the 
mass has been deflected, engages in a locking fashion with a securing pin 
extending into the housing of the belt retractor and through a mounting 
wall. With the belt not being deployed, it may be possible to dismount the 
belt retractor and, under certain circumstances, to trigger the indicator, 
but in such case the securing pin could no longer be introduced. 
In all of the above noted constructions of the present invention, it is 
apparent that the additionally advantageous informative value of being 
able to ascertain as to whether or not the safety belt had been worn 
during an impact which generates predetermined forces has been determined 
by the instant invention. The magnitude of the belt load occurring in case 
of an impact is recorded by an indicator incorporated into the belt strap 
and/or by a deformation element interposed, for example, at a mounting 
point of the belt system. 
Accordingly, it is an object of the present invention to provide a sensor 
arrangement triggerable by a predetermined deceleration force which 
avoids, by simple means, shortcomings and disadvantages encountered in the 
prior art. 
Another object of the present invention resides in providing a sensor 
arrangement forming a part of the safety belt system of a motor vehicle 
which provides an indication as to whether or not the safety belt was worn 
at the time of occurrence of predetermined decleration forces. 
Another object of the present invention resides in providing a sensor 
arrangement forming a part of a safety belt system for a motor vehicle 
which is simple in construction and therefore relatively inexpensive to 
manufacture. 
Another object of the present invention resides in providing a safety belt 
arrangement forming a part of a safety belt system for motor vehicles 
which includes an indicator means actuatable upon the occurrence of 
predetermined deceleration forces which exceed the deceleration forces 
normally attained by a braking maneuver of the motor vehicle. 
A still further object of the present invention resides in providing a 
sensor arrangement forming a part of a safety belt system for motor 
vehicles which provides with a high degree of probability a reliable 
indication as to the use of the safety belt during a collision of the 
motor vehicle. 
Yet another object of the present invention resides in providing a sensor 
arrangement forming a part of a safety belt system for motor vehicles, 
adapted to be triggered by predetermined deceleration forces, which 
functions reliably under all operating conditions.

Referring now to the drawings wherein like reference numerals are used 
throughout the various view to designate like parts, and, more 
particularly, to FIG. 1. According to this Figure, a belt strap 1 of a 
safety belt system is received or accommodated by a latch tongue 2 which 
is adapted to be inserted into a lock housing 3. The lock housing 3 is 
fixedly mounted by way of a deformation element 4 to a solid or fixed 
vehicle part (not shown). In an inserted and latched position of the latch 
tongue 2, a lower zone 5 of the latch tongue 2, indicated in phantom 
lines, closes a contact 6 so that a voltage supply to a terminal 7 is 
applied, through a wire 8, to a spring 9, with the spring 9 acting on a 
ball 1 forming a component of a sensor generally designated by the 
reference numeral 10. 
The ball 11 acts as an inert mass generally designated by the reference 
numeral 12 and is adapted to be deflected from a mounting means generally 
designated by the reference numeral 13 upon an attainment of a 
predetermined deceleration amounting to about 5 g, rolling upwardly along 
a sloping track 14 until is abuts against a contact 15 which is preferably 
generally toroidal-shaped and provided at least with an electrically 
conductive layer 16. Since the ball 11 consists of an electrically 
conductive material or has an electrically conductive coating and the 
track 14 is non-conductive, the ball 11 acts as an electrical contact 
between the opening 9 and contact 15 wherein the at least partially 
relaxed spring 9 prevents an interruption of the electrical contacting and 
thereby insuring a current flow by way of a wire 17 connected to the 
conductive layer 16 to an indicator generally designated by the reference 
numeral 18 which is connected to a ground 19. The indicator 18 includes a 
safety element 20 such as, for example, a fuse or the like which is burned 
through and destroyed as the current flows from the wire 17 to the ground 
19. As a result of the safety element 20 being burned through, a reliable 
indication is obtained with a high probability of certainty as to whether 
the safety belt had been worn during a preceding impact or collision of 
the motor vehicle. 
As shown in FIG. 2, a sensor generally designated by the reference numeral 
10a is constructed as a tubular element 21 which includes a track or guide 
generally designated by the reference numeral 14 which extends in a curved 
and ascending path. The tubular element 21 accommodates a liquid 22 which 
functions as an inert mass generally designated by the reference 12a. The 
tubular element is supported on a belt mounting point 23 with a cover 
plate 24, secured, if necessary, against turning, and having mounted there 
on a free end of a belt system in a manner not illustrated in detail in 
the drawings. The cover plate 24 receives the tubular element 21 which 
tubular element is likewise mounted so that it is, if necessary, secured 
against turning. Sealing lips 26 project in an alternating fashion from 
inner walls 25 of the tubular element. 
If a predetermined strong deceleration occurs, the liquid 22 moves, 
depending upon an installation position of the cover plate 24, ascendingly 
toward one side or the other side. Due to the simultaneously occurring 
application of strong belt forces, due to deceleration, being introduced 
by way of the tubular element 21 to the belt mounting point 23, a 
permanent deformation is imparted into the tubular element 21. During this 
process of permanent deforming, the sealing lips 26 respectively contact 
the opposite inner walls 25 and thus prevent a backflow of the liquid 22 
into the original position. 
If the tubular element 21 is constructed from a transparent material and 
the liquid 22 is dyed or otherwise colored, a degree of deflection of the 
liquid can readily be ascertained. However, it is also possible in 
accordance with the present invention to utilize, in place of a liquid 22 
a ball which, for example, leaves an externally visible impression during 
a deformation of the tubular element 21, the specifics of which will be 
discussed later. 
As shown in FIGS. 3 and 4, a sensor generally designated by the reference 
numeral 10c may be provided with an indicator generally designated by the 
reference numeral 18c, with the sensor 10c and indicator 18c being 
accommodated in a lock housing 3c of a safety belt system not shown in 
detail. An inert mass generally designated by the reference numeral 12c is 
fashioned as a ball 11 and, during normal driving, rests in a depression 
or cavity 27 arranged in a bottom zone of the lock housing 3c. As shown in 
FIG. 3, a latch tongue 2 is adapted to be inserted into the lock housing 
3a and locked in place by pins 28 which, in a manner not illustrated in 
detail, can be caused to disengage by a conventional release key arranged 
at the lock housing 3c. 
With the latch tongue 2 in the position illustrated in FIG. 3, a lower end 
of the latch tongue 2 downwardly presses an ejector 29, with the ejector 
29 being under the force of at least one spring in a manner not 
illustrated in the drawings. By a correspondingly fashioned zone 30 of the 
spring loaded ejector 29, the ball 11 is prevented from leaving the 
depression 27 even in case of a strong deceleration. 
If the latch tongue may be introduced into the lock housing 3 after a 
collision of the motor vehicle so that the self holding function takes 
effect, it can be assumed with a high degree of probability that the belt 
system had been worn during the collision. On the other hand, if the belt 
system was not worn during the collision, then the ball 11 is capable of 
leaving the depression 24 upon the occurrence of the predetermined 
deceleration due to the ejector 29 being connected in front at a spacing 
therefrom so that the elements assume the position shown in FIG. 4. With 
the elements positioned in the manner shown in FIG. 4, if an attempt is 
made to introduce the latch tongue 3, the ejector 29, before locking of 
the latch tongue 3 has taken place, abuts against the ball 11 and a 
further use of the safety belt is prevented. Furthermore, in such a case, 
it can be assumed that the safety belts have not been deployed at the time 
of impact or collision of the motor vehicle. 
As shown in FIG. 5, a sensor generally designated by the reference numeral 
10d and an indicator generally designated by the reference numeral 18d may 
be accommodated in a lock housing 3d, with an inert mass generally 
designated by the reference numeral 12d taking the form of a ball 11 
adapted to be accommodated in a depression 27d. A sloping planar surface 
31 is arranged on a top side of a holder 33 at a position following the 
depression 27d. The holder 33 is supported against a lock housing 3d 
through the interposition of a spring 32. A stop 34 provided on the holder 
33 limits a stroke of the spring 32 and assumes a distance from the lock 
housing 3d if higher belt forces become effective. 
A finger 35 projects inwardly from the lock housing 3d at a position 
beneath an ejector 29d, with the ejector 29d being spring loaded in a 
manner not shown and preventing the ball 11 from jumping out of the 
depression 27 during vibrations which normally occur during a driving 
operation of the motor vehicle. A two armed lever generally designated by 
the reference numeral 36 is disposed above the finger 35, with one arm 37 
of the lever 36 being under the bias of a spring 38 the other arm 39 is 
urged against a shoulder 40 projecting inwardly from the holder 33. 
In the position illustrated in FIG. 5, the latch tongue 2 is inserted and 
the ejector 29d is in its lower position. If a predetermined deceleration 
occurs, the ball 11 leaves the associated depression if the lock housing 3 
has moved upwardly to a corresponding extent against the bias of the 
spring 32. The ball 11 rolls to the lowermost point of the sloping plane 
31 and is jammed in place at that location toward the lock housing 3 when 
the belt force decreases and the spring 32 becomes effective. Since now 
the holder 33 can no longer completely enter, a spacing remains between 
the stop 34 and the lock housing 3 so that it can be assumed with a high 
degree of certainty that the belt had been worn during a preceding 
accident or collision of the motor vehicle. 
In the above noted path of motion of the holder 33, the arm 39 in contact 
with the shoulder 40 initially pivots downwardly until its other arm 37 
abuts the ejector 29d. If a strapped in passenger frees himself after the 
collision by releasing the belt, then the ejector 29 moves upwardly and 
releases the arm 37 which later thereupon pivots downwardly due to the 
action of the spring 38. The arm 37 is thereby disposed in a path of 
movement of the ejector 29d so that further insertion of the latch tongue 
2 to a point of achieving a further locking action is no longer possible. 
As shown in FIG. 6, a sensor generally designated by the reference numeral 
10e includes an inert mass generally designated by the reference numeral 
12e in the form of a pendulum 41 having a bearing plate 42 which rests on 
a fixed rim 43. An indicator generally designated by the reference numeral 
18e includes a pivotably mounted angle lever 44 having an extension 45 
which presses on the bearing plate 42 and a free angled end 46 which is 
adapted to dip into a guide slot 47 of a guide 48 which is traversed by a 
belt strap 1 adapted to be extracted from a retractor 49. A blocking 
device (not shown) of conventional construction and the belt retractor 49 
blocks the reel of the retractor as soon as a deceleration of about 0.5 g 
occurs. If the deceleration reaches a value effecting a deflection of the 
pendulum 41, then the bearing plate 42 is tilted and the free end 46 of 
the angle lever 44 is further moved into the guide slot 47 until the belt 
strap is stressed. Since, at the same time, due to the so called film reel 
effect, a limited length of belt strap 1 is stilled pulled out with the 
reel being blocked, the free end 46 is entrained until the latter jams in 
the wedge-like converging guide slot 47 with the belt strap 1 so that this 
circumstance again admits a conclusion that the belt had been deployed. 
As shown in FIGS. 7 and 8, a sensor generally designated by the reference 
numeral 10f and an indicator generally designated by the reference 18f are 
accommodated in an interior of a schematically illustrated belt retractor 
49f. An inert mass generally designated by the reference numeral 12f in 
the form of a ball 11 rests in a depression 27f defined at a spacing from 
an annular bead 50. A fixedly mounted lever 51 engages a detent tooth 52 
arranged in the manner of a ratchet, with the lever 51 being provided with 
a cutout 53. A spring 55 supported on a bracket 54 extends through the 
cutout 53 and acts on the ball 11. 
A feeler generally designated by the reference numeral 56 is fashioned as a 
two armed lever with a lower arm 57 and an upper arm 60 which includes a 
roller 59 at its distal end. The lever is pivoted as at P and the lever 
arm 57 is urged outwardly by a spring 58 resting on a bracket 54 in such a 
manner that a roller member 59 at the end of the upper arm 60 of the 
feeler 56 is in contact with the belt strap 1 coiled on a reel 61. The 
lower arm 57 of the feeler 56 has protruding means which engages and 
depresses the lever 51 during normal driving of the motor vehicle. 
As shown in FIG. 8, the feeler 56 pivots aside and releases the lever 51 
when the belt strap 1 is unwound during application of the safety belt due 
to the diminishing diameter of the belt on the reel occassioned by the 
retraction of the belt. If upon reaching a predetermined deceleration, the 
ball 11 is deflected, the detent tooth 52 meshes with a toothed rim 62 
which may, for example, form a marginal zone of the reel 61. At this point 
in time, a blocking device (not shown) of conventional construction which 
responds as early as a deceleration of about 0.5 g, blocks the reel 61. 
Once the ball 11 is deflected, as seen in FIG. 8, it is precluded from 
returning to depression 27f by the extension of spring 55. 
If after an accident or collision of a motor vehicle, the belt is released, 
the belt strap is automatically wound up since the detent tooth 52 
resiliently yields in the manner of a ratchet. However, if an attempt is 
made to again unreel a length of belt strap 1, then the detent tooth 52 
comes into contact with a stop 63 and blocks the toothed rim 62. In this 
manner by simply exerting a pull on the belt strap, a determination can be 
made as to whether the belt strap had been applied at the time of the 
preceding accident or whether such application was neglected. 
The construction of FIGS. 9 and 10 apart from a few small structural 
differences, essentially corresponds to the arrangement of FIGS. 7 and 8 
with respect to its basic features. For the sake of clarity, an arm 60g 
adapted to sense the diameter of the coil of the belt strap present on the 
reel 61 is merely schematically indicated. In the construction of FIGS. 9 
and 10, the inert mass generally designated by the reference numeral 12g 
rests, during normal driving operation, in a depression 27g and is held in 
position by a spring loaded lever generally designated by the reference 
numeral 51g which is pivoted about P'. The lever 51g is provided with an 
extension 64 projecting in a direction of a securing pin 66 extending 
through a wall of the belt retractor 49 and a mounting wall 65 associated 
therewith. 
An arm 57g of the feeler generally designated by the reference numeral 56g 
is adapted to release the inert mass 12g as soon as the belt strap is 
unwound in a manner not illustrated in detail in the drawings. If a 
deceleration of about 0.5 g occurs in this position, then the inert mass 
12g, tilts toward the side permitting extension 64 to be moved downwardly 
by spring S and thereby engage a detent tooth 52g with and block the 
toothed rim 62g. At the same time, the extension 64 engages the securing 
pin 66 with a locking action so that the pin 66 can thereafter no longer 
be removed and serves as evidence or an indication as to whether or not 
the safety belt was worn. 
If in the condition of the arrangement shown in FIG. 9, the belt retractor 
49 is dismounted and the indicator generally designated by the reference 
18g is triggered by a manipulation, then the securing pin 66 can no longer 
be inserted without damage. 
As seen in FIG. 11, a sensor generally designated by the reference numeral 
10h is constructed as a tubular element 21 which includes a track or guide 
generally designated by the reference numeral 14 which extends in a curved 
and ascending path. The tubular element 21 accommodates a ball 11 which 
functions as an inert mass generally designated by the reference numeral 
12h. The tubular element is of the same or similar arrangement to that 
shown in FIG. 2 wherein the element is supported on a belt mounting point 
23 with a cover plate 24, secured, if necessary, against turning, and 
having mounted thereon a free end of the belt system in a manner not 
illustrated in detail in the drawings. The cover plate 24 receives the 
tubular element 21 which tubular element is likewise mounted so that it 
is, if necessary, secured against turning. 
Provided that a deceleration occurs which generates forces of or exceeding 
a predetermined amount, the ball 11 moves, depending upon an installation 
position of the cover plate 24, ascendingly toward one side or the other 
side. In response to the simultaneously occurring application of strong 
belt forces, due to deceleration, being introduced by way of the tubular 
element 21 to the belt mounting point 23, a permanent deformation is 
imparted into the tubular element 21. During this process of permanent 
deformation, and subsequent to the ball 11 having been deflected, the 
inner walls 25 will engage the ball element and be deformed therearound 
giving a positive indication of the position to which the ball had been 
deflected during deceleration. Accordingly, the degree of deceleration can 
readily be ascertained. 
While we have shown and described several embodiment in accordance with the 
present invention, it is understood that the same is not limited thereto 
but is susceptible of numerous changes and modifications as known to one 
having ordinary skill in the art and we therefore do not wish to be 
limited to the details shown and described herein, but intend to cover all 
such modifications as are encompassed by the scope of the appended claims.