The present invention relates particularly, although by no means exclusively, to a shock absorbing member for absorbing impact energy of a motor vehicle.

The present invention also relates particularly, although by no means exclusively, to a crash barrier system for motor vehicles based on the shock absorbing member.

Conventional crash barrier systems for motor vehicles include guard rails, chains, or other substantially rigid barriers which are designed to absorb impact energy of motor vehicles. Conventional crash barrier systems also include arrays of air bags and foam blocks enclosed by guard rails which form less rigid barriers which nevertheless are capable of absorbing impact energy of motor vehicles. However, a common problem with these known systems is that they are not resilient and thus must be repaired or replaced altogether if contacted by a motor vehicle.

An object of the present invention is to provide a crash barrier system based on shock absorbing members that are resilient that alleviates the disadvantage of the known crash barrier systems described in the preceding paragraph.

According to the present invention there is provided a shock absorbing member formed from a granulated

rubber bonded together by a glue.

The rubber and the glue form a continuous matrix.

The matrix makes up part of the volume occupied by the member, and air makes up the remainder of the volume.

The applicant has found in crash tests of motor vehicles that the shock absorbing member is capable of absorbing substantial impact energy by compressing in response to motor vehicle impact and, in view of the resilience of the rubber, recovers to its original shape after a motor vehicle impact.

The granulated rubber may be made by any suitable means.

Preferably the granulated rubber comprises granulated tyres.

Preferably the ratio of rubber to glue by volume is 3:1 to 5:1.

More preferably the ratio of rubber to glue by volume is 4:1.

The glue may be any suitable glue.

Preferably the glue is a polyurethane-based glue.

Preferably the member includes 30-80% by volume air.

More preferably the member includes 40-70 vol.% air.

Typically the member includes 55-65 vol.% air.

Preferably the member is formed in a mould without applying pressure to form the member.

Preferably the rubber and the glue are pre-mixed in the reguired proportions, delivered to the mould, and allowed to air cure.

The granulated rubber may be of any suitable shape, particle size, and particle size distribution.

By way of example, the granulated rubber may be fibrous, ie have a relatively high aspect ratio, or may have relatively uniform dimensions.

The shape, size, and size distribution of the particles of granulated rubber, the ratio of rubber to glue, and the vol.% air in the member, may be varied as required to obtain different combinations of energy absorption and resilience in the member.

A preferred use of the shock absorbing member is to absorb impact energy of a motor vehicle.

In this connection, according to the present invention there is also provided a motor vehicle crash barrier system which includes one or more than one of the shock absorbing member.

Preferably the crash barrier system includes a means for locating the or each member in relation to a ground surface.

In a situation where the purpose of the crash barrier system is to protect a motor vehicle from direct impact with a structure, such as a post, preferably the locating means includes a pair of guide rails which extend along opposite sides of the or each member and a means for

securing the guide rails to the ground surface. The purpose of the guide rails is to confine the members to compress, in response to vehicle impact, towards the structure thereby decelerating the vehicle as it moves towards the structure.

Preferably, the crash barrier system includes a guard rail or other suitable deflection barrier.

The crash barrier system may include any suitable arrangement of a plurality of the shock absorbing member.

The crash barrier system may comprise a selection of different-shaped shock absorbing members.

It is preferred that the shape of the shock absorbing member be suited for a crash barrier system for motor vehicles.

As noted above, the shape, size, and the size distribution of the particles of granulated rubber, the relative proportions of the rubber granules and the glue, and the amount of air, may be varied as required to obtain different combinations of resilience and energy absorption in the shock absorbing member.

This is an important feature for a motor vehicle crash barrier system formed from a plurality of the shock absorbing member, since in many instances it is desirable that shock absorbing members have a range of combinations of resilience and energy absorption depending on a range of factors including, but not limited to: (i) the positions of the shock absorbing members in the crash barrier system: (ii) the vehicle speed limit on the roadway; and

(iii) the weights of the vehicles that may collide with each barrier system.

By way of example, in a preferred crash barrier system, the shock absorbing members are selected and arranged so that the resilience of the members decreases with distance from the roadway. The purpose of such an arrangement is to progressively absorb the impact energy of a motor vehicle without bringing the vehicle to an abrupt stand-still.

According to the present invention there is provided a method of forming the shock absorbing member described above which includes the steps of: (a) supplying a mixture of a granulated rubber and a glue to a mould; and (b) without applying pressure to the mould, allowing the mixture to cure to form the member.

The applicant arranged for a series of crash tests to be carried out by an independent laboratory on a series of samples of a preferred shock absorbing member in accordance with the present invention.

The samples tested were in block form and, specifically, were 700mm long/700mm wide/lm high, 500mm long/500mm wide/lm high, and Im long/lm wide/lm high. The samples were moulded with rubber: polyurethane glue ratios of 4:1 and 5:1 by volume. The samples included 55-60 vol.% air.

In most cases the samples were positioned against a rigid barrier. In a limited number of cases the samples

were spaced between 400mm and Im in front of the barrier.

A vehicle was driven into each sample at a preset speed and measurements were made of parameters including the deceleration of the vehicle after impact and the compression of the samples. The impact speeds selected were 15, 20, 25, and 30 km/hr.

The results are set out in the following table. Block Size Make Impact Contact Deceleration Compression Max Vel Area Centre (g's) (mm) Rebound (km/hr (M2) Vel (km/hr) 700x700 4:1 U 15 0.595 7.37 230 6.0 (65.9) (93.1) (165.4) 700x700 4:1 U 15 0.595 7.32 240 5.6 (55.0) (96.5) (165.3) 700x700 4:1 U 20 0.595 10.64 290 10.4 (54.9) (84.3) (169.1) 700x700 4:1 U 25 0.595 15.65 350 12.5 (60.4) (78.8) (162.2) 700x700 4:1 U 30 0.595 21.74 400 13.8 (64.9) (73.6) (145.7) 700x700 4:1 U 15 0.595 6.25 250 5.9 (75.4) (102.6) (178.3) 700x700 5:1 U 25 0.595 14.32 380 10.2 (69.0) (88.2) (171.0) 700x700 5:1 U 25 0.595 16.72 310 12.9 (64.5) (71.9) (137.4) 500x500 4:1 U 15 0.425 8.70 230 7.8 (70.2) (89.0) (173.1) 1000x1000 5:1 U 30 0.850 14.71 480 14.9 (65.3) (95.8) (208.6) 700x700 4:1 U 30 0.385 15.94 560 14.9 (88.0) (102.5) (214.2) 700x700 5:1 U 30 0.385 16.80 600 15.3 (94.1) (105.8) (232.9) Note: The numbers in brackets ( ) represent the time after initial impact<BR> in milliseconds.

The results of the crash tests summarised in the table indicate that the shock absorbing member is an effective alternative to known crash barrier systems.

Many modifications may be made to the preferred embodiment described above without departing from the spirit and scope of the present invention.