WO1997018971A2

WO1997018971A2 - Energy absorbing device

Info

Publication number: WO1997018971A2
Application number: PCT/IL1996/000153
Authority: WO
Inventors: David Douenias
Original assignee: Kav Mitar Yizum Venihul Proyectim Ltd.
Priority date: 1995-11-17
Filing date: 1996-11-17
Publication date: 1997-05-29
Also published as: AU7504296A; WO1997018971A3

Abstract

An energy absorbing device for restraining a safety belt on impact is provided. In one embodiment, the device includes a cylindrical housing having a circular opening at a first end thereof, a piston unit reciprocally located within the housing, and a triggering unit connected to the housing. The piston unit includes a flat edge defining a vacuum section and a piston rod connected at one end thereof to the safety belt. The triggering unit is primed by expelling air from vacuum section and locking the piston rod. When the safety belt is subject to impact forces, the triggering unit releases the piston rod thereby tightening the safety belt around the occupant.

Description

ENERGY ABSORBING DEVICE

FIELD OF THE INVENTION

The present invention relates to a system for restraining the occupant of a vehicle, particularly of motor vehicles. More specifically, the invention relates to a restraining device for safety belts.

BACKGROUND OF THE INVENTION

Safety belts and similar restraining systems are fitted to vehicles in order to protect the occupant wearing the safety belt from being propelled forward in the event of a collision or sudden acceleration force. The safety belt must be able to effectively restrain the occupant while at the same time be able to absorb the energy generated by the sudden force.

It is known to use a piston and cylinder arrangement for absorbing energy. For example, U. S. Patent No. 3,343,874 to Hildebrandt describes a safety device which includes a braking cylinder filled with fluid which is attached to one end of a safety belt. The cylinder progressively increases the braking force on impact and also progressively returns the belt to its original position after the energy has been dissipated.

U. S. Patent No. 3,901 ,531 to Prochazka which describes a device which is tensioned by a pressure cylinder device which is, in turn, actuated by deceleration sensitive devices. There is provided a structure for insuring that the tension applied to the restraining device does not exceed a predetermined value. In one embodiment, a relief valve vents the pressure fluid from the cylinder at a predetermined value of pressure and in another embodiment the device is comprised of a mechanical relief device interposed between the cylinder and the restraining device.

U.S. Patent No. 3,891 ,271 to Fieni describes a piston/cylinder unit attached to a safety belt which uses fluid within the piston to stress the safety belt during an impact . The unit is designed to intentionally leak if the force projecting the user forward exceeds a predetermined value. The latter patent to Fieni uses a combustible pyro-technical substance which ignites thereby forcing the piston to be activated. Prochazka uses ignitable rocket boosters within the piston which are activated on impact. These systems are potentially dangerous. All of the above referred to patents rely on a fluid or gas propellant to respond to and negate forces due occurring on impact .

Numerous systems have been proposed for absorbing the impact energy by deformation. For example, U. S. Patent No. 4,027,905 to Shimogawa et al describes: a seat belt system where one end of a seat belt is firmly engaged with one end of a steel strip which, in turn, is held and guided by an anchor member firmly attached to a vehicle body. Impact energy acting upon the seat belt forces the steel strip out of the anchor member causing the strip to be plastically deformed in at least at two positions.

U. S. Patent No. 3,973,650 to Nagazumi also describes a mechanical energy absorbing device and safety harness which includes an elongated member plastically deformable in a Iongitudinal direction when subjected to a mechanical force greater than an elastic limit of the member.

Alternative devices which have been proposed for absorbing energy include, for example, a device described in U. S. Patent No. 3,583,530 to De Venne. The device comprises two relatively movable elements. One element carries at least one mass of elastically yieldable material and the other element has an enlarged head having a profile substantially symmetrical relative to a plane transverse to the direction of relative movement of the elements. This head must force its way through the mass by compressing the latter transversely and locally whereby energy is absorbed. U. S. Patent No. 3,547,468 to Gluffrida describes an energy absorbing device having a generally U-shaped housing having a plurality of pins extending between the sidewalls. A double layer of strip metal is threaded through the pins and, when the strip metal is pulled through the pins as a result of the load placed on the belt system, the metal bends and absorbs energy. U. S. Patent No. 4,256,273 to Burieigh describes a safety belt retractor which has a spindle provided with an outer layer formed of a material which is capable of absorbing energy by substantially inelastic deformation. When the safety belt is subject to shock-loading exceeding a predetermined level, this outer layer is crushed, leading to a reduction in the effective diameter of the spindle and thereby allowing an additional length of the belt to be paid out after the spindle has been loaded.

The shock loading imposed on the safety belt following severe impact may drastically deform the unit. If the device is fitted to the vehicle, especially in an inaccessible location, it may be difficult tc replace. Furthermore, the user may not be aware of the extent of deformation and that the unit is no longer effective and requires replacement. Known devices tend to be expensive to manufacture and replace.

SUMMARY OF THE PRESENT INVENTION

It is an object of the present invention to provide a restraining device for a safety belt which on impact allows the safety belt to be tightened around the wearer so as to securely restrain the occupant in position. There is therefore provided, in accordance with a preferred embodiment of the present invention, a restraining device for a safety belt, which includes:a cylindrical housing having a circular opening at a first end thereof, a piston unit reciprocally located within ihe housing, and a triggering unit connected to the housing. The piston unit includes a flat edge defining a vacuum section and a piston rod connected at one end thereof to the safety belt. The piston rod slides transversely through the circular opening of the housing. The triggering unit has two position settings. The triggering unit creates a vacuum within the vacuum section of the housing. The first position locks the piston rod and the second open position allows the piston rod to freely move through the circular opening. Furthermore, in accordance with a preferred embodiment of the present invention, when the safety belt is subject to impact forces, the triggering unit is activated to release the piston rod which releases the vacuum and effects a tightening of the safety belt around the occupant.

Additionally, in accordance with a preferred embodiment of the present invention, the restraining device further includes adjusting means for controlling the rate of movement of the piston unit. The adjusting means includes a pair of venting holes formed within the first end of the housing, a circular flange integrally formed around the external circumference of the housing at the first end and a circular disc. The circular disc is rotatably retained by the circular flange and has a plurality of pairs of orifices. One of the pairs of orifices is aligned with the pair of venting holes.

Furthermore, in accordance with a preferred embodiment of the present invention, each pair of orifices has a different diameter.

Furthermore, in accordance with a preferred embodiment of the present invention, the cylindrical housing also includes at least a single one-way valve integrally fitted within the closed end of the housing. The cylindrical housing also includes a plurality of valves integrally fitted around the external circumference of the housing at the first end.

Additionally, there is provided, in accordance with a preferred embodiment of the present invention, an energy absorbing device for a safety belt, which includes a plate having a slot through which a loop for said safety belt is extendable and energy dissipating apparatus. At least some of the impact forces are absorbed by the energy dissipating apparatus. The energy dissipating apparatus is retained by the loop of the safety belt.

Furthermore, in accordance with a second preferred embodiment of the present invention, the energy absorbing device includes a pair of plates connected together and two energy dissipating apparatuses. Each of the plates has a slot through which a loop for the safety belt is extendable and each loop retains one of the energy dissipating apparatuses.

Furthermore, in accordance with another preferred embodiment of the present invention, the energy absorbing device includes a plate and two energy dissipating apparatuses. The plate has two slots through which loops for the safety belt are extended. Each loop retains one of the energy dissipating apparatuses.

Additionally, in accordance with the preferred embodiments of the present invention, the energy dissipating apparatus includes a hollow outer tube filled with compressible material and apparatus for closing the hollow tube at each end thereof.

Additionally, in accordance with the preferred embodiments of the present invention, the hollow outer may include an inner tube and the space between the outer and inner tubes is filled with compressible material. Furthermore, in accordance with the preferred embodiments of the present invention, some of the impact forces are initially absorbed by the compressible material and secondarily absorbed by the inner tube.

Furthermore, in accordance with the preferred embodiments of the present invention, the hollow outer tube is generally elliptical. The inner cylinder is composed of a material capable of elastic deformation. The compressible material is polyurethane or a foamed plastic material. Additionally, in accordance with the preferred embodiments ofthe present invention, the energy -dissipating apparatus further includes safety belt gripping apparatus. The safety belt gripping apparatus includes at least one L-shaped protrusion integrally molded to each of the closing elements.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which:

Fig. 1 is an illustration of a vehicle driver using a safety belt fitted with the restraining device, constructed and operative in accordance with a preferred embodiment of the present invention;

Fig. 2A is a sectional view of the restraining device of Fig. 1 in its open position;

Fig. 2B is a sectional view of the restraining device of Fig. 1 in its locked position;

Fig. 3 is an exploded cross-sectional view across line 3-3 of Fig. 2A;

Fig. 4 is an illustration of a vehicle driver using a safety belt fitted with the restraining device, constructed and operative in accordance with a preferred embodiment of the present invention; Fig. 5 is an exploded view of the restraining device of Fig. 4;

Fig. 6 is a sectional view of the restraining device of Fig. 4; and

Fig. 7 is a sectional view of the restraining device of Fig. 4 subjected to impact forces; and

Fig. 8 is an exploded view of a further embodiment of the restraining device of Fig. 4.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference is now made to Figs. 1 , 2A, 2B and 3 which illustrate a safety belt restraining device 10 for a safety belt, constructed and operative in accordance with an embodiment of the present invention. Safety belt restraining device 10 comprises a piston device 12 which is attached at one end to a suitable anchorage point 14 such as the floor of a vehicle and, at its other end, to a safety belt 16 via sliding member 17. An operating mechanism 18 acts as a triggering device is connected to piston device 12. Piston device 12 is primed to create a vacuum within the device and locked in position. The force of an impact releases the locked operating mechanism 18 causing the piston device 12 to be activated and tighten the safety belt 16 around the vehicle driver.

Piston device 12 comprises a cylindrical housing 20 having a circular opening 21 at one end 22 through which a piston rod 24 slidingly transverses. A packing seal 25 surrounding piston rod 24 protects piston rod 24 and opening 22. Piston rod 24 is integral at one end with a piston body 26 slidingly fitted along the inner cylindrical wall 28 of housing 20. Piston body 26 divides housing 20 into two sections, a vacuum section 27 and an air section 29. A seal 30 is interposed between piston body 26 and wall 28. Seal 30 ensures that air from air section 29 is prevented from entering vacuum section 27. A sliding member 17 is integrally formed at the other extremity of rod 24.

At least a single one-way valve 32 is integrally fitted within the closed end

34 of cylindrical housing 20. One-way valve 32 is used to expel air from within housing 20. A plurality of valves 36 are integrally fitted around the circumference of housing 20 proximate to end 22 to allow air to enter cylindrical housing 20. A circular annulus 38 is fitted to the inner cylindrical wall 28 proximate to valves 36.

A pair of venting holes 40 are drilled in housing 20, either side of end 22, and diametrically opposite each other. A circular flange 42 is integrally formed around the external circumference of housing 20, at end 22. Flange 42 extends beyond housing 20. A groove 44 is formed within flange 42 for the purposes of retaining a circular disc 46. Circular disc 46 has a knurled edge 47 for ease of rotation and comprises a plurality of pairs of orifices 48. Each pair of orifices 48 has a different diameter. The diameter of each of the orifices 48 determines the amount of air which can pass through each pair of orifices 48 into air section 29 of housing 20. Thus, by rotating disc 46, it is possible to adjustably select the rate at which air passes through air section 29. The minimum amount of force necessary to restrain a seat belt user varies with the weight of the user. By adjusting the volume of air passing through air section 29 the force acting on piston body 26 due to the flow of air can be varied Therefore, by adjusting the size of the orifices 48, the restraining force due to the action of the piston device 12 can be adjusted to suit the user's weight. Operating mechanism 18 comprises a lever 50 pivotally connected at one end to an arcuate base element 52. Base element 52 extends from circular flange 40 and is welded, or otherwise suitably attached, to circular flange 40. A balancing element 54 is attached to lever 50 at a distal end from base element 52. A hole 56 is formed within lever 50 to allow piston rod 24 freedom of movement. In an alternative embodiment, an electronic shock assessment system, of a type known in the art, can be fitted to operating mechanism 18 to act as the triggering device.

Lever 50 is pivotal about two positions; an open position (Fig 2A) and a closed position (Fig. 2B) respectively. When lever 50 is in its open position (shown by dashed lines), it is generally perpendicular to base 52 and piston rod 24 can slidingly transverse through hole 56. The natural, default position for lever 50 is its closed position (shown by full lines) where it acts to lockingly restrain piston rod 24.

To prime piston device 12, lever 50 is released from its closed position by manually pulling the lever 50 away from circular disc 46 towards sliding member 17 and holding it perpendicular to base 52 (in its open position). Piston body 26 is then pushed back towards closed end 34. Air within vacuum section 29 of cylindrical housing 20 is expelled via one-way valves 32. Then, piston body 26 is slidingly pulled back until checked by circular annulus 38. A vacuum then exists within vacuum section 29. Lever 50 is returned to its closed position, locking lever 50 in place and thereby preventing piston body 26 from sliding back towards closed end 34. Circular disc 46 is rotated within groove 44 so that a pair of orifices 48, corresponding to the weight of the vehicle driver, are aligned with venting holes 40.

The effect of sudden acceleration forces, due to a collision, for example will generally cause lever 50 to be released from its locking position. When lever 50 is released, and since there is a vacuum in vacuum section 27 of housing 20, there is nothing to prevent piston body 26 from traveling back to closed end 34. The action of piston body 26 causes the safety belt 16 to tighten around the driver, thereby restraining him.

After a collision or whenever the lever 50 of piston body 26 is activated, the piston device 12 can be reused by simply resetting the lever, as described hereinabove, without the need to replace any expensive components.

Reference is now made to Figs. 4, 5 and 6 which illustrate an energy absorbing device 100 for a safety belt, constructed and operative in accordance with an embodiment of the present invention. Energy absorbing device 110 comprised energy dissipating means 112, which is secured to safety belt 110 by means of a fastening loop 114 and a plate 116. Energy dissipating means 112 contains compressible material 150.

Safety belt 110 is anchored to the vehicle body by conventional means, known in the art. When the vehicle is subjected to sudden acceleration forces, the safety belt 110 tightens. This sudden tightening causes the energy absorbing means 112 to be compressed. At least part of the energy generated by the impact forces is absorbed by compressible material 115.

A narrow rectangular shaped slot 118 (Fig. 5) is molded within plate 116, which is generally rectangular in plan. The fastening loop 114 is formed by passing a portion of the safety belt 110 through slot 118. The energy absorbing means 112 is inserted within fastening loop 114 extending thorough slot 118.

Energy absorbing means 112 comprises a hollow elliptically shaped tube

122 and optionally, an inner tube 124 inserted therein. Hollow tube 122 is closed at each end by, for example a female threaded cap 126. A pin 128, or similar rigid component, extending the full length of inner tube 124, is inserted within inner tube

124 to provide it with strength. The inner surface of each cap 126 is configured to receive inner tube 124 and pin 128, so that when cap 126 is attached to hollow tube 122, inner tube 124 and pin 128 are held in place by cap 126. An L-shaped protrusion 130 is integrally molded to the external surface of each cap 126. The protrusion 130 extends beyond the width of the cap 126 and over the safety belt 110, thereby holding the safety belt 110 in position.

The space between inner tube 124 and hollow tube 122 is filled with compressible material 115, such as polyurethane, capable of absorbing energy forces imposed by shock loading. Inner tube 124 is preferable composed of a light flexible material, such as aluminum, which has high elasticity properties. Hollow tube 122 may be constructed of any suitable material capable of elastic deformation.

Reference is now made to Fig. 7 which illustrates the effect of sudden acceleration forces on the energy absorbing means 112, due to a collision, for example. Generally, the force of the impact causes the safety belt 110 to tighten around the driver. The safety belt 110 is pulled away from energy absorbing means 112, as shown by arrows 132. The tightening of safety belt 110 tends to straighten plate 116 (as shown by arrow 133) and push it towards the energy absorbing means 112. The slot 118 forms the weakest part of the plate 116 and thus, if the impact forces are excessible, the plate 116 will tend to crease about slot 118 and become deformed. After impact, plate 116 assumes a straightened position 116'.

The tightening of safety belt 110 produces compressive forces (shown by arrows 134) on the outer hollow tube 122 of energy absorbing means 112 tending to "flatten" the hollow tube 122 so that its generally elliptical shape becomes more circular These compressive forces are transferred to the inner compressible material 115 which absorbs the main impact forces. Forces in excess of those absorbed by compressible material 115 are then absorbed by inner tube 124, which being constructed from a thin elastic material, is also compressed. Pin 128 prevents inner tube 124 from completely collapsing on account of transferred impact forces. After an accident or whenever the energy absorbing means 112 is damaged, the energy absorbing means 112 and plate 116 can be easily replaced. The loop 114 of safety belt 110 is undipped from the L-shaped protrusions 130 and pulled up. Energy absorbing means 112 and plate 116 are then removed from the safety belt 110. Replacement parts for both elements (energy absorbing means 112 and plate 116) are then inserted as described hereinabove. Reference is now made to Fig. 8 which illustrates a second embodiment of the restraining device, generally designated 200. Similar elements in Figs. 8 and 5 serve similar functions and are designated by similar reference numerals.

Energy absorbing means 200 comprises a pair of elliptically shaped tubes 122 and a plate 216. Elliptically shaped tubes 122 are similar to the tubes 122, as described hereinabove with respect to the embodiment of Fig. 5 and are, therefore, not described.

Energy absorbing means 200 is secured to a safety belt by 110 means of a plurality of fastening loops 214 and plate 216. Plate 216 comprises a pair of generally rectangular plate 218 connected to each other about a mid-point 220. The angle a between plates 218 is obtuse and preferably between 90° and 180°.

Alternatively, plate 216 comprises a single plate creased about its mid¬ point 220, so that an obtuse angle a is formed.

A narrow rectangular shaped slot, 222, similar to slot 118 is molded within each plate 216. The fastening loops 214 are formed by passing a portion of the safety belt 110 through each slot 222 so that energy absorbing means 220 can be inserted.

In a similar manner to that described with respect to Fig. 7, the force of an impact tends to propel the occupant forward. The safety belt 120 restrains the occupant. In this embodiment, the initial impact forces are absorbed by the mid- point 220. Generally, plates 218 move further away from each other, that is, the angle a between the plates 218 becomes more obtuse tending towards 180°.

As described hereinabove with respect to the embodiment of Fig. 7, excessive impact forces compresses outer hollow tube 122 causing the hollow tube

122 to become more circular. Inner compressible material 115 absorbs the main impact forces. Forces in excess of those absorbed by compressible material 115 are absorbed by inner tube 124. It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather the scope of the present invention is defined only by the claims which follow:

Claims

1. An energy absorbing device connected to a safety belt holding an occupant in position, comprising: a. a cylindrical housing having a circular opening at a first end thereof; b. a piston unit reciprocally located within said housing, said piston unit comprising: i. a flat edge defining a vacuum section; and ii. a piston rod connected at one end thereof to said safety belt, said piston rod sliding transversely through said circular opening; and c. a triggering unit connected to said housing, said triggering unit having a first closed position for locking said piston rod and a second open position allowing said piston rod to freely move through said circular opening, whereby said triggering unit is primed by expelling air from said vacuum section and retaining said piston rod, and whereby, when said safety belt is subject to impact forces, said triggering unit is activated to release said piston rod thereby effecting a tightening of said safety belt around said occupant.

2. An energy absorbing device according to claim 1 further comprising adjusting means for controlling the rate of movement of said piston unit, said adjusting means comprising: a. a pair of venting holes formed within said first end of said housing; b. a circular flange integrally formed around the external circumference of said housing at said first end; and c. a circular disc, rotatably retained by said circular flange, said circular disc having a plurality of pairs of orifices, wherein one of said plurality of pairs of orifices is aligned with said pair of venting holes.

3. An energy absorbing device according to claim 2 wherein said pairs of orifices have different diameters.

4. A restraining device according to any of the previous claims and wherein said cylindrical housing further comprises at least a single one-way valve integrally fitted within a second closed end of said housing.

5. An energy absorbing device according to any of the previous claims and wherein said cylindrical housing further comprises a plurality of valves integrally fitted around the external circumference of said housing at said first end.

6. An energy absorbing device according to any of the previous claims and wherein said triggering unit is connected an electronic shock assessment system for ascertaining the impact forces.

7. An energy absorbing device for a safety belt, comprising: a. a plate having a slot through which a loop for said safety belt is extendable; and b. at least one energy dissipating means retained by said extended loop, whereby when said safety belt is subject to impact forces, at least some of said impact forces are absorbed by said energy dissipating means.

8. An energy absorbing device according to claim 7 and further comprising a second slot formed within said plate, said safety belt being further extendable through said second slot.

9. An energy absorbing device according to claim 7 and further comprising a second plate connected to said first plate, said second plate having a slot through which a second loop for said safety belt is extendable.

10. An energy absorbing device according to any of claims 7 -9 and wherein said energy dissipating means comprises: a. a hollow outer tube filled with compressible material; and b. means for closing said hollow tube at each end thereof.

11. An energy absorbing device according to claim 10 and further comprising an inner tube inserted within said outer tube.

12. An energy absorbing device according to any of claims 7 - 9 and wherein said energy dissipating means comprises: a. a hollow outer tube; b. an inner tube inserted within said outer tube; c. compressible material filling the space between said inner and outer tubes; and d. means for closing said hollow tube at each end thereof, wherein said closing means are configured to receive said inner tube.

13. An energy absorbing device according to any of claims 10 - 12 and wherein said hollow outer tube is generally elliptical.

14. An energy absorbing device according to any of claims 11 - 13 and wherein said inner tube is composed of a material capable of elastic deformation.

15. An energy absorbing device according to any claims 11 - 14 and wherein said energy dissipating means further comprises a rigid inner core inserted within said inner tube.

16. An energy absorbing device according to any of claims 10 - 15 and wherein said compressible material is a polyurethane.

17. An energy absorbing device according to any of claims 10 - 15 and wherein said compressible material is a foamed plastic material.

18. An energy absorbing device according to any of claims 7 - 17 and wherein said energy dissipating means further comprises safety belt gripping means.

19. An energy absorbing device according to claim 18 and wherein said safety belt gripping means comprises at least one L-shaped protrusion integrally molded to each of said closing means.

20. An energy absorbing device according to any of claims 10 - 19 and wherein at least some of said impact forces are initially absorbed by said compressible material.

21. An energy absorbing device according to any of claims 11 - 19 and wherein at least some of said impact forces are absorbed by said inner tube.

22. An energy absorbing device according to any of claims 1 - 21 substantially as described hereinabove.

23. An energy absorbing device according to any of claims 1 - 21 substantially as illustrated in any of the drawings.