GB2202920A - Impact retardation device - Google Patents

Abstract

An impact retardation device consists of a piston 2 and a metering pin 5 encased in a cylinder 1. When the moving body impacts a buffer 4 attached to the piston 2, a fluid or gas within the cylinder is initially compressed and then gradually released via an orifice at 6 through which the metering pin passes. The rate of deceleration of the body being arrested can be varied by shaping the metering pin 5. <IMAGE>

Description

TMFACT RETnOAT!ON DVICF This invention relates to an impact retardation device Retardation devices , sometimes called 'shock absorbers' vary in their design and materials , Common types are 1) buffers on railway wagons usually consisting of a coil spring which is compressed upon impact 2) Leaf springs , such as used on road vehicles and railway carriage suspensions , 3) Telescopic shock absorbers to complement leaf springs also used for aircraft and motor cycle suspensions , 4) Rubber compressible shock absorbers , and 5) collapsible metal structures , Most of these devices are designed to cushion the effect of an impact or to absorb the kinetic energy of a moving bod to avoid damaging that body The present invention provides a means of regulating the rate of retardation ( negative acceleration or deceleration ) to give any shape of require acceleration parameter , The cushioning of a body impacting the retardation device is achieved by means of a piston compressing a gas or fluid ( hitherto called the medium ) in a cylinder , ttached to the rear of the piston in the cylinder is a metering pin which passes through a sealed orifice at the rear of the cylinder , As the medium is compressed by the force on the piston created by the impact , the metering pin passes through the orifice and depending upon the the shape of the metering pin the pressure exerted by the medium on the piston is either increased maintained or decreased A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing; in which Figure 1 shows the piston at the start of its stroke just after the device has been impacted by the bdy required to be decelerated , At this point the medium n , which has been inserted into the cylinder through the valve S at the rear end of the cylinder , is being compressed , Since the medium is not allowed to escape fron the cylinder there is an increase of pressure , thus increasing the force on the rear of the piston which in turn creates a corresponding increase in the rate of deceleration of the body Figure 2 shows the position where the piston and metering pin have moved to a point where the diameter of the metering pin has been reduced , In this position the medium is allowed to escape from the cylinder through the orifice , maintaining or reducing the pressure as required on the piston At this point the force on the rear of the piston is either maintained or reduced thus maintaining or reducing the rate of deceleration of the body Figure 3 shows a typical deceleration curve At At a point 'a' in time the piston will have reached the position shown in figure 2 , the medium will begin to exhaust from the cylinder causing the rate of deceleration to decay , Foint 'b' will be the position of the piston when the medium has been completely eçhausted from the cylinder and the body impacting the buffer has come to rest Referring to the drawings the retardation device consists of a cylinder 1 enclosed at each end , Within the cylinder is a piston 2 incorporating a seal 3 between the outer diameter of the piston and the inner diameter of the cylinder . Attached to the front of the piston is a buffer 4 with its rod projecting from the piston and through the front end of the cylinder Fastened to the rear of the piston is a metering pin 5 , whose shape determines the characteristic of the deceleration curve of a body impacting the buffer , The metering pin passes through an orifice at the rear of the cylinder which incorporates a seal 6 around the metering pin To provide pressure on the rear of the piston , a medium consisting of a fluid or a gas 7 , is fed into the cylinder via a valve 8 , initially forcing the piston to the front of the cylinder , Rs the buffer is impacted , the medium is either compressed , or release via the orifice to maintain or reduce the pressure , depending upon the shape of the metering pin , For safety, the valve 8 can be utilised to discharge the medium from the cylinder

Claims (1)

1. Cì AlUc 1, Nn impact retardation device comprising a cylinder , buffer , piston and metering pin , cushions a body impacting the buffer by means of compressing and releasing a gas or fluid 2 An impact retardation device as claimed in claims I wherein regulating the pressure e::erted by the gas or fluid on the rear of of the piston is achieved by means of controlling the discharge of the gas or fluid through an orifice by a shaped metering pin attached to the rear of the piston 3 An impact retardation device as claimed in claims 1 and 2 wherein the retardation of a body impacting the buffer of the device is regulated to a specific designed deceleration parameter A An impact retardation device as claimed in claims 1 ,2 and 3 wherein the retardation of a body impacting the buffer of the device can be regulated to achieve varying retardation characteristics , such a; ; square wave , sinusoidal , cosine , haversine , triangular and multipeak wave forms 5, fin impact retardation device substantially as described herein with reference to figures 1 - 3 of the accompanylng drawings