As known, many vehicles such as cars, lorries, trucks and similar are equipped with safety belts fitted within the cabin, next to the driver and pas- senger seats.

Generally, a safety belt takes the shape of a band or strap connected at two points to the side stay of the vehicle.

The belt is provided with a fastening buckle or spline intended to snap into a locking device placed laterally with respect to the seat opposite to the stay. In this way, when the fastening buckle is placed into the locking device, the belt strap di- vides in two bands respectively surrounding the pas- enger's abdomen and chest.

The locking device is generally provided with one or more buttons intended to be manually pressed by the user in order to allow disengagement of the fas- tening buckle.

The belt is normally wound into a wind- ing/unwinding mechanism placed inside the stay of the

vehicle chassis.

The winding/unwinding mechanism tends to keep the belt wound. A light pulling action exerted on the belt band allows its unwinding from the wind- ing/unwinding mechanism in order to unloose the belt, while an abrupt pull of the band (suggestive of an accident or a sharp braking) causes a temporary jam- ming of the winding/unwinding mechanism so that the belt can perform its retaining function on the pas- senger.

When the vehicle experiences a particularly strong impact due to a serious accident, often the winding/unwinding mechanism jams permanently, not al- lowing the unloosing of the belt. As a consequence, the passenger or driver can remove the belt only act- ing on the locking device buttons.

However, in this case the belt unlocking opera- tion proves to be extremely complex because, upon the winding/unwinding mechanism jamming, the belt band can not be unloosen. Furthermore, because of the ac- cident, the passenger lacks the strength to press the releasing buttons of the locking device.

It should further be considered that often, due to high traction suffered by the locking device dur- ing impact, its unlocking mechanism completely jams

and can not be unfastened.

As a result, rescue operations of accident vic- tims entrapped by the belts are difficult, slow and complex and can cause further physical damage to the victims. It should further be noted that a delay in rescue operation can often have serious consequences on the accident victims.

An object of the present invention is to avoid prior art drawbacks by providing a safety belt cut- ting device suitable to free a person from the belt after an accident.

Another object of the present invention is to provide a safety belt cutting device that is versa- tile and can be fitted to various types of vehicles and safety belts.

Another object of the present invention is to provide a safety belt cutting device that is inexpen- sive and easy to produce.

These objects are met according to the invention with the features listed in independent claim 1 en- closed.

According to the invention, the safety belt cut- ting device is mounted on the vehicle stay and it is suitable to cut the band or strap of the safety belt in order to allow the user to free from the safety

belt in case of jamming of the belt unlocking device.

The present invention benefits, consisting of in- creased security of vehicle passengers in case of ac- cident, are evident.

Further characteristics of the invention will be- come clear from the following detailed description, that refers to merely exemplary and not limiting em- bodiments shown in the drawings enclosed, in which: Figure 1 is a perspective view schematically showing a safety belt to which the cutting device of the present invention is applied; Figure 2 is a front view of a first embodiment of the cutting device according to the present inven- tion; Figure 3 is a sectional view taken through the section plane III-III of figure 2; Figure 4 is a front view of a second embodiment of the cutting device according to the present inven- tion; Figure 5 is a block diagram showing an automatic operating system of a third embodiment of the cutting device according to the present invention; Figure 6 is a partial sectional view showing a fourth embodiment of the cutting device driven by an engine by means of a screw drive; and

Figure 7 is a partial sectional view showing a fifth embodiment of the cutting device driven by an engine by means of a chain or belt drive.

The safety belt cutting device according to the invention, marked as a whole with reference number 1, is described by figures.

Figure 1 shows a safety belt 2 applied on a user 3 seated on a vehicle seat 4. The safety belt 2 in- cludes a band or strap 5 that is wound/unwound by a winding/unwinding mechanism (not shown) known per se, generally placed inside the base of the vehicle chas- sis stay 6.

The band 5 of the belt passes through a first buckle 7 mounted on the top of the stay 6, substan- tially at the height of the head rest 10 of seat 4.

Then, the band 5 goes through a casing 9 within the stay 6 to be wound into winding/unwinding mechanism.

The other end of band 5 is connected to a second buckle 8 fixedly mounted on the stay base.

A fastening buckle 11, is slidably mounted on band 5, which buckle is intended to snap into a lock- ing device 12 mounted on a pliable tube 13 disposed on the seat 4 side opposite to the stay 6. The lock- ing device 12 is provided with a button 14 intended to be pressed by the user in order to release the

fastening buckle 11. When the fastening buckle 11 is fastened to the locking device 12, the belt 2 has a first portion surrounding the waist of the user 3, and a second portion diagonally surrounding the user chest.

The cutting device 1 is placed inside stay 6, substantially at the height of the user's shoulders, and is intended to transversally cut the band 5 of the belt within the casing 9 defined into the stay 6.

As shown in figure 2 and 3, in a first embodiment of the invention, the cutting device 1 includes an holder 20 supporting a cutting element 21 placed into the casing 9 of stay 6 in which the safety belt band 5 passes.

Holder 20 is slidably mounted linearly into a transversal guide slot 23 made in the stay 6. In this way, holder 20 can move from a starting position at the beginning of its travel (as shown in figures 2 and 3) to a final position at the end of its travel.

Obviously, holder 20 can be provided with a car- riage or slide running into a guide or rail transver- sally made in stay 6.

The cutting element 21 cooperates with an oppos- ing element 24 placed inside casing 9 of the stay 6.

The belt band 5 abuts against the opposing element

24. In this way, when the holder 20 goes through the slot 23, the cutting element 21 crosses the belt band 5 cutting it.

The cutting element 21 can be comprised of a blade or an elongated thin cutting element or a cut- ting wire element, for instance.

Holder 20 is urged in its linear motion by spring means 25. The spring means can be a coil compression spring placed into casing 9 and interposed between a stay 6 side and support 20. When support 20 is in its starting position, the spring 25 is compressed.

Locking means 26 are mounted on stay 6 in order to lock the holder 20 in its starting position. The locking means 26 can be comprised of a retainer hav- ing a stem 27 and a head 28. The stem 27 of retainer 26 seats against the body of holder 20 locking it, and the head 28 of retainer 26 protrudes from the stay 6 to be manually accessed by the user.

Retainer 26 can move from a locking position in which it interferes with holder 20, to an unlocking position in which it does not interfere with holder 20, clearing its cutting travel.

The user 3, by operation of the retainer head 28, clears holder 20 that, through the cutting element 21, cuts the safety belt band 5.

Hereafter, the elements that are identical or correspond to those already described are marked with the same reference numbers and their detailed de- scription is omitted.

In fig. 4 a cutting device 100 according to a second embodiment, in which the retainer 26 has been removed, is described.

To this end, a bayonet coupling system has been conceived, making a substantially L shaped guide slot 123, in which holder 20 can move, in stay 6. In this case, when holder 20 is in the vertical leg of the L shaped slot 123, it is locked; support 20 unlocks when it is in the horizontal leg of the L shaped slot 123.

In this case, holder 20 must be provided with a head 130 protruding outwardly from the stay 6 to be manually operated by the user.

Of course, in case of manual operation of the re- tainer 26 and the head 130 of holder 20, the spring 25 can be removed as well and the user can manually slide holder 20 to cut the belt band 5.

In figure 5 a cutting device 200 according to a third embodiment of the invention, in which the unlocking of holder 20 has been automated, is de- scribed.

In this case, holder 20 is locked by means of an automatic locking device 226 which can be unlocked by and electric command signal CO. The automatic locking device 226 can be for instance a solenoid actuator comprising a cylinder 228 in which are electric coils suited to generate a magnetic field in order to drive piston 227. The piston 227 can move from an protrud- ing locking position in which it locks holder 20, to an unlocking retracted position in which it clears the holder 20 travel.

In this version, a control system 240 including three sensors is provided: a first accident sensor 241, a second vehicle stop sensor 242, and a third buckle locking sensor 243.

The accident sensor 241 is to detect a serious accident. The accident sensor 241 can be connected to the vehicle airbag to sense the airbag blowing due to a serious accident and subsequent airbag deflation.

The accident sensor outputs a command signal Cl imme- diately after the airbag deflation.

The vehicle stop sensor 242 is to detect the ve- hicle stop. For example, the vehicle stop sensor 242 can be a movement sensor connected to the vehicle chassis in order to sense the vehicle movement with respect to the ground. The vehicle stop sensor 242 is

arranged to output a command signal C2 when the vehi- cle is not moving any more.

The buckle locking sensor 243 is to detect the buckle 11 locking into the locking device 12 (figure 1). The buckle locking sensor 243 can be a contact sensor installed into the locking device 12 and ar- ranged to sense the presence of the fastening buckle 11 of safety belt into the locking device 12, and to output a command signal C3 accordingly.

The outputs of the three sensors 241,242 e 243 are connected to a logic AND, the output of which is connected to a delay timer 245. In this way, when all three command signals C1, C2, C3 coming from sensors 241,242, 243 are declared, the delay timer 245 is activated and, after a predetermined delay time, for instance 10 seconds, the timer 245 outputs the com- mand signal CO activating the automatic locking de- vice 226.

It has to be noted that the accident sensor 241 ensures the belt cutting only in case of serious ac- cident, the vehicle stop sensor 242 ensures the belt cutting only when the vehicle is motionless, and the buckle locking sensor 243 ensures the belt cutting only when the buckle is fastened to the locking de- vice. Of course, if one of these requirements is not

met, the locking device 226 is not activated.

The timer 245 ensures an automatic locking device 226 activation delayed enough to allow the user, if necessary, to unfasten the buckle 11 from the locking device 12, thus avoiding a useless cutting of safety belts.

In the above description, the holder 20 is oper- ated by elastic or spring means 25. However, as will be hereafter described, the holder 20 can also be op- erated by motorization.

Figure 6 shows a cutting device 300 according to a fourth embodiment of the invention, in which the holder 20 is mounted in a female screw or internal thread 350 that threads on a screw 351. The screw 351 being rotated about its own axis by an electric motor M.

In this way, the rotation of the screw 351 causes a linear translation of the female screw 350, which is guided in a transversal runner into the vehicle stay 6.

Figure 7 shows a cutting device 400 according to a fifth embodiment of the invention, in which holder 20 is mounted on an endless loop chain or belt drive 460.

The belt/chain 460 is moved'by two pul-

leys/sprockets 461, one of which is operated by mo- torization.

The motorization of the fourth and fifth embodi- ments of the invention can be operated by a button which is pressed by a user or by a remote control or by control unit 240, which is described in the third embodiment of the invention.

Of course, instead of motorizations via electric motors, other means can be provided to operate the holder 20, such as pneumatic, oleo-dynamic, electric or magnetic linear actuators.

Many changes and modifications of details can be made to the present embodiments by a person skilled in the art, which variations are within the scope of the invention as pointed out in appended claims.