JPS60131350A - Absorber for impact energy - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention is disclosed in, for example, US Pat. No. 3,700,273 (
Shaxson et al.).

Prior to the present invention, hydraulic energy absorbers were used to attach shock absorber assemblies to vehicle underframes or other support structures. Some of these devices include a pair of deflated and inflatable fluid chambers hydraulically interconnected by a flow control orifice element and cooperating metering rods to adjust the fluid flow rate between the chambers. and the device is folded into a nest by impact force so as to thereby absorb impact energy.

A spring device is used to return the cylinder to the extended position after the impact load is removed.

In an example of a prior art device exemplified by U.S. Pat. Preferably, additional internal water flow is added to bypass the orifice.

Another conventional energy absorbing device, exemplified by U.S. Pat. A blow-off plug or weak wall section can be provided to vent hydraulic fluid to the outside of the device to reduce build-up. This design applies high forces to the vehicle until the blow plug ruptures, after which the energy absorption capacity of the device is virtually eliminated.

Although conventional structures such as these should be mostly satisfactory,
They are relatively complex in construction and operation, and also generally do not have the improved internal pressure relief provided by the present invention.

The present invention makes available a crash energy absorbing device that is simple in design and effective in reducing the level of forces experienced on the energy absorbing device in response to severe crashes, thereby making it possible to The possibility of failure of the device as a result of internal pressure build-up under heavy loads can be effectively eliminated.

This result can be achieved with minimal structural changes to some of the previously used energy absorbing devices.

The frangible flange means supporting the orifice means of the device thus allows the orifice to close during high velocity impingement to provide a large diameter flow passageway between the chambers for internal pressure relief to prevent pressure bursting of the device. The means of energy absorption continues to be provided throughout the disassembly and folding of the energy absorbing device.

The orifice means may comprise a floating orifice for optimal cooperation with a regulating rod that controls the flow rate between the chambers prior to disengagement of the orifice means.

Now, with particular reference to Figure 1 of the drawings, the underframe 1 of the car chassis
0 is shown constructed with a pair of laterally located side 1ni rails 12 having forwardly extending projections 14 connected by front intersecting members 16. Front and rear flip-up brackets 18 are bolted to each protrusion 14 and are spaced longitudinally from each other to connect identical left and right energy absorbing devices 22 to the chassis underframe 10 . Each energy absorber 22 has its associated front (outermost)
It has an outer cylinder 24 which extends through the circular opening in the bracket 18 and is in turn welded at 26 to a collar 28 which is bolted or otherwise securely coupled to the front bracket 18. The outer cylinder 24 is sealed at one end by a circular end cap 30 welded or otherwise coupled thereto.

A threaded implant port 32 securely secured to the cap 30 and projecting axially therefrom extends through an opening 34 in the bracket 20. The stud bolt 32
A nut 36 threaded into securely connects the end cap 30 and thus the outer cylinder 24 to the bracket 20.

In addition to the outer cylinder 24, each energy absorbing device 22 includes an inner cylinder 38 mounted for limited nesting motion within the cylinder 24 and projecting forwardly therefrom. The forward end of the inner cylinder 38 has a base plate welded thereto adapted to be connected to a shock absorber assembly 41 by means of a coupler means 42.
) 40.

The interior of the cylinder is defined by intermediate and rear fluid chambers 46 and 48.
A separate cylinder cap 44 is coupled to the inner (rear) end of the inner cylinder 38 so that each fluid chamber is filled with a suitable hydraulic fluid, such as oil. A thin-walled cylinder cap sleeve 50 made of a suitable material such as a glass-filled polyamide plastic material (nylon) covers the cylinder cap 44 for a sliding fit over the inner diameter of the outer cylinder 24. can be installed.

However, there is sufficient clearance between the sleeve 50 of the cap and the cylinder 24 to allow direct communication between the chamber 48 and the interior space 51 formed between the inner and outer cylinders. . The front end of this inner space is sealed by an elastic cylindrical sleeve 52 made of Teflon, polyamide plastic material or other suitable material, located between the cylinders 24 and 38 and held by a stop sleeve 53. The stop sleeve 53 is a metal cylindrical lug that is held in a tight fit over the cylinder 38. A floating thin metal plate piston 54 is centered in the inner cylinder 38, fitted with an O-ring 56 separating the intermediate chamber from a front chamber 58 formed between the floating piston 54 and the plywood 40. The gas consisting of hl is compressed in the chamber 58, and the gas is injected through a hole 60 formed in the plywood and then confined in the chamber 58 by a ball 62 welded to the hole 60. It is being The force of the gas compressed within the chamber 58 acts on the oil within the device 22 to force the cylinders 38 and 24 to the normally extended position shown in FIGS. 1 and 2.

The stop sleeve 53 is held rigidly against the cylinder 38 and has a tapered head (53) that contacts an inwardly bent end 65 of the cylinder 24 to limit outward thrusting movement of the cylinder 38 with respect to the cylinder 24. bead)6
It has 3. The stop sleeve 53 extends rearwardly to support the resilient sealing sleeve 52. In addition to providing a fluid seal, the sleeve also functions as a control device for returning the device when it is moved from a collapsed or retracted position toward a fully extended position.

The cap sleeve 50 has an outer circumferential portion that is curved around the outer end of the circumference of the cap 440, and has an outer circumferential portion that is curved around the outer end of the circumference of the cap 440 and has
It has an inner peripheral portion extending radially inwardly to partially cover the surface of 4.

As shown in FIGS. 2 and 3, cap 44 is formed with a central circular hole 66. As shown in FIGS. Living tree ($ (main bo)
dy ) 59 and annular outwardly extending radial flanges 0 and 72 spaced laterally to spacedly enter opposite ends of the cylinder cap 44 directly surrounding the nucleation 66 . An orifice element 68 is radially movably mounted within the bore 66 of the cap 44. The Frandef 0 is brittle and allows the main body to detach from the nucleation 66 under certain pressure conditions. The orifice element 68 is dimensioned so that it can float or slide radially within the bore 66 and relative to the cap 44. This orifice element may be made of mild steel or a material having a long operating life under pressures resulting from low impact conditions and effective to ensure that the flan def is sheared or dislodged under the high pressure loads of high speed impacts. Made of a suitable metal such as brass or a suitable plastic material.

An elongated adjustment rod 76 welded or otherwise secured to the end cap 30 extends axially into the energy absorbing device 22 and projects through the central annular surround 1 portion 78 of the orifice curvature 68. do. The adjustment rod and orifice element cooperate to progressively reduce the orifice area for adjustment fluid between the chambers 48 and 46 so that the device 22 moves linearly with impingement loads up to a predetermined maximum load. The rods 76 are arranged at different angular positions 6 with respect to the centerline of the rod over the length of the rod so as to exhibit different depths with respect to the cylindrical dimension of the rod.
It is preferably formed with three equally spaced flats 80, only one of which is shown in the figure. The rod is otherwise sized proximate the inner diameter of the orifice element 68 so that the curved portion of the adjustment rod guides the orifice element as the device moves linearly.

For example, during 8 km/h (5 miles 4σ hours) or other low speed energy absorbing action for impact forces that nest the cylinders 38 inward, the adjustment rod 76 as the cap moves over the rod 76. Any slight axial misalignment between the holes 66 and 66 is due to a limited amount of radial floating movement of the orifice elements 68 as allowed by the radial clearance of the orifice elements 68 from the ends of the holes 66. Adapted.

The flat portion 80 of the adjustment rod provides a decreasing orifice area between the rod and the orifice element as the inner cylinder moves linearly into the outer cylinder due to impact forces on the buffer assembly. With this structure, during a low-speed collision, the chamber 4
8 contracts so that the fluid flows into the intermediate chamber 46 from which it expands through the decreasing orifice area;
A substantially constant pressure is maintained. When this occurs, the floating piston 54 advances to further compress the gas in the chamber 58, which, after the impingement load is removed, is forced into the fully extended position shown in FIG. A spring force is provided to subsequently extend the absorber.

The reciprocating movement of fluid between the chambers during an impact dissipates the impact energy as more fully explained in the above-referenced US Pat. No. 3,700,273. When the collision load is removed, the compressed gas in the chamber 58 acts as a gas spring, exerting a spring force on the oil in the intermediate chamber 46 and forcing it into the rear chamber 48.
Push it inward. Thus, the intermediate chamber contracts and the rear chamber 48 expands to its original position during extension or rebound of the energy absorbing device 22.

During high-speed collisions of various shock absorber assemblies, such as 40 km per hour (25 mph) collisions, high pressure build-up, e.g. A certain amount of fluid flows into chamber 46 through defined orifice element 68 . Main body 6 of the orifice element
9 is sheared off from its flange when the hydraulic pressure exerted on the main body exceeds a predetermined pressure, such as may occur during the high speed impact conditions described above. Under such circumstances, hole 66 is thus opened to increase the hydraulic flow between chambers 46 and 48. From the rear chamber 48 to the intermediate chamber 46
This increased flow of oil into the chamber 48 effectively reduces the pressure build-up within the chamber 48 to a level that maintains the integrity of the cylinder 24 and the energy absorbing device.

Although the hole 66 in the cap 44 is opened under high pressure, there is still some restricted flow between the flat of the adjustment rod and the inner wall of the cap forming the orifice 66.

The flutter remaining around the adjustment rod may also provide some restriction to oil flow. In any case, the pressure is effectively relieved with the impact energy being dissipated by the remaining restriction between the adjustment rod and the hole in the cap. After the impact load is removed, compressed gas in chamber -58 acting through piston 54 directs hydraulic fluid from chamber 46 through hole 66 into chamber 4.
8, thereby moving the energy absorbing device to its extended position.

The embodiment shown in FIGS. 4-9 is substantially similar to the embodiment of FIGS. 2 and 3, and reference numerals applied to the embodiment of FIGS. 2 and 3 refer to similar constructions of the embodiment of FIGS. 4-9. It is considered to be the same as the element.

In the embodiment of FIG. 4, a thin-walled orifice element 88 made of mild steel is operatively mounted for radial movement within the central bore 66 of the cylinder cap 44 of the inner cylinder 38. The orifice element has a breakaway annular flange 90 that contacts the inner surface of the cylinder cap. The main body 92 of the orifice is conical or expanded after being inserted through the bore 66 and thus remains nucleated during normal energy absorption and rebound reciprocation. The floating or radial movement of orifice element 88 accommodates the axial misalignment of piston rod 76 and annular opening 94 provided by the orifice element.

The operation of the energy absorbing device of FIG. 4 is substantially the same as the embodiment of FIG. In normal operation, inner cylinder 3
8 moves to a retracted position upon impact and fluid flows from chamber 48 to chamber 46 through the orifice opening to effect energy absorption. Upon rebound, the gas spring moves the energy absorbing device to the extended position as previously described. In a high-velocity impact, the conical body axially expands due to the build-up of pressure in the chamber 48 so as to open the cap hole 66 for increased fluid flow indicated by arrow A between the chambers as previously described. in response to the crab being sheared away from the flutter 90. This reduces pressure build-up within the device and prevents the device from bursting under high internal pressure.

5 and 6 illustrate another embodiment of the invention,
There, the central hole 66 of the cylinder cap 44 is laterally spaced apart by an annular radially extending flatter 98 surrounding the rear and front surfaces of the cylinder cap, respectively.
and 100 conical metal orifice elements 96
to store. It retains the orifice element in the cylinder cap 44 during the compression and return strokes of the energy absorber. Adjustment rod 76 extends through an annular opening 102 formed between the rod and the orifice element. The cap is also formed with upper and lower fluid passages 104 and 106 having annular shoulders 108 and 110 in which metal rupture discs 112 and 114 are mounted. These rupture discs are fixed in the annular retainer 1 by pressing into the opening of the cap 44.
16 and 118 to hold it in place.

In normal operation, the orifice element functions as in the previous embodiment to control rod 7 to regulate fluid between chambers 46 and 48 during energy absorption and rebound strokes.
Cooperate with 6. The aforementioned fluid spring provides the driving force to move the device to the return position after the impact force is removed.

In the event of a severe impact, the orifice element 96 is sheared away from the flange 100 so that there is increased flow from chamber 48 to chamber 46 through nucleation 66 as indicated by flow arrows B. If the pressure is not sufficiently relieved, rupture discs 112 and 114 rupture to provide an auxiliary flow path through the cap as shown by arrow C for flow to bypass hole 66 as best seen in FIG. Will. This structure reduces pressure to such an extent that the cylinder and energy absorber retain their integrity.

In the embodiment of FIG. 7, the orifice element 118 is a thin metal plate.
is attached to hole 66 in end cap 44. The orifice element has a radially extending annular flange 120 that engages the back surface of the cap 44. The orifice element includes a narrowed annular opening 122 that houses the adjustment rod 76.
and further includes a cylindrical extension 124 to facilitate its insertion into the hole 66 of the cap. By then deforming or otherwise bending extension 124 from the dotted line position to the solid line position, orifice element 118 moves end cap 4 for radial floating movement in bore 66.
Captured by 4. In the event of a low velocity impact, the orifice element and adjustment rod cooperate as in the previous embodiment to effectively regulate the fluid between chambers 48 and 46 for energy absorption and rebound. Upon a high speed impact, the annular flange 120 is bent or sheared to separate the main body of the orifice element from the bore 66 as described above in conjunction with other embodiments. With the orifice again displaced from hole 66, flow control is provided to effectively reduce pressure build-up in chamber 48 to a level at which the cylinder will not burst.

The embodiment of FIG. 8 has a structure and operation similar to the design of FIG. In FIG. 8, the orifice 128 of the thin metal plate
is the radial flange 1 in contact with the back side of the cap 44
It has 30. The orifice element has an annular opening 132 of decreasing diameter formed by back-bending the thin metal plate to accommodate the adjustment rod 76. The orifice element further has a cylindrical extension from which a plurality of tangs 136 are stamped. These cores are positioned outwardly for initial installation such that the orifice element is pushed into the bore 66 and held there for radial floating movement by the core 136 and flange 130. form a spring finger that extends to .

Low speed operation is as described in connection with the previous embodiment. The high speed impact causes a build-up of pressure within the chamber 46, which causes the flange 13 to swell as described in connection with the embodiment of FIG.
Bending or shearing 0. This allows the orifice element to be moved axially from the bore 66 in order to effectively increase the size of the opening between the two chambers bounded by the bore 66 restriction. The opening between the nucleation and control rod is such that pressure build-up in chamber 48 is reduced to protect the device from rupture.

In FIG. 9, the cylinder cap 44 is formed with a circular shouldered seat 140 onto which a stepped annular metal retainer 144 is pressed and secured. The retainer includes an annular seat for a washer-like rupture disc 146 made of a suitable thin steel material. The rupture disc is held on the sheet by an annular retainer 148 which is pressed and secured to the sheet, as shown in FIG.

An annular metal orifice 150 in the shape of an eyelet is mounted for floating movement over the rupture disc 146. As shown, the opposing flanges of the eye surround the wall of the rupture disc.

There is sufficient radial clearance between the inner annular end forming the central opening of the rupture disc and the eye-shaped orifice element 150 to allow floating movement of the orifice element. As in the previous embodiment, the orifice element operates to regulate the flow during both the energy absorption and rebound strokes for low speed (8 km/h; 5 mph) impacts.

In the event of a severe impact, the rupture disc 146 is sheared and the orifice element is therefore forced to increase the flow between pressure chambers 48 and 46 (both pressures due to the main flow) for effective pressure relief in the chambers 48. Move axially from its normal position to increase the opening between the chambers.

[Brief explanation of the drawing]

1 is a perspective view of a pair of energy absorbing devices according to the present invention showing an underframe of a vehicle chassis and a shock absorber assembly attached to the underframe; FIG. 2 is a perspective view of the underframe of a vehicle chassis; FIG. 2; FIG. 3 is a portion of the energy absorbing device of FIG. 2 illustrating that the desorption orifice element provides dissipation of high pressure energy under conditions of overload; Figure 4 is an enlarged cross-sectional view of the
Figures 5 and 6 are partial cross-sectional views similar to Figures 3 and 4 illustrating an alternative embodiment of the energy absorbing device according to the invention before and after a high-speed collision; and Figures 7.8 and FIG. 9 is a partial cross-sectional view similar to FIGS. 3-6 showing an additional alternative embodiment of the energy absorbing device according to the present invention prior to a high speed collision. [Explanation of the ladle numbers of the main and lower parts] 10: Underframe; 24: Nijirinder; 30: Outer end wall; 38: First cylinder; 41: Buffer assembly; 44: Cap means; 46: No. 2nd room; 48:
50, 53: Support means; 54, 58: Spring means; 66: Hole; 68 Niorifice means; 69: Soil body; 7
0: Fragile flange means; 76: Elongated sloping adjustment bin; 78: Confined fluid flow path; 112.114: Rupture means. Procedural amendment + V + Sum 59 ++-7Jl // Fl Commissioner of the Patent Office
Shiga Gakuden 1, Display of matter f'1 1981 Patent Application No. 25520
2 No. 2, Title of the invention 3, Relationship between the person making the amendment 411 and 1 Ushi Patent applicant 4, Agent 5, Number of inventions increased by amendment 1 (1) [Claims] amended as shown in the attached sheet do. 2. Claim 1: A collision energy absorbing device for loading a shock absorber assembly on a support of a motor vehicle, comprising first and second cylinders mounted for telescopic movement between an extended position and a retracted position.
the first and second cylinders having stop means cooperating to establish an extended position of the cylinder;
said first cylinder having cap means at one end thereof and slidably disposed over said second cylinder for providing said energy absorbing device (d) and a second variable volume fluid chamber; a first and second cylinder; a hole extending through said cap means; hydraulic fluid in said first and second chambers; and said first chamber responsive to telescopic movement of said cylinder to said retracted position. fluid flow control means for controlling the flow of fluid from the cylinder into the second chamber, the fluid flow control means dissipating the energy of the impact load to a predetermined magnitude so that the cylinder In an impact energy absorbing device comprising orifice means operably disposed within the aperture of the cap means to provide a fluid flow control passageway for regulating the fluid flow rate between the chambers as the cap means moves toward the position. further comprising frangible means forming part of said orifice means, wherein a fluid force exceeding said predetermined magnitude ruptures said frangible means and displaces said orifice means from said aperture, thereby increasing the fluid flow rate through said aperture. and the increased flow rate from the first chamber to the second chamber allows the pressure build-up in the second chamber to be alleviated (so that the device does not rupture the cylinder). Increased collisions A collision energy absorbing device, characterized in that the orifice means is held in a detachable manner to adapt to the energy of a load. 2. The collision energy absorbing device according to claim 1. A collision energy absorbing device, characterized in that the collision energy absorbing device is installed in the first cylinder for telescopic movement with respect to a second cylinder. 3. The collision energy absorbing device according to claim 1 or 2. orifice means in said aperture of said cap means comprises an annular orifice means for controlling fluid flow through said cap means, and said frangible means is such that movement of said orifice means from said cap means is within a predetermined minimum range. in response to an applied high-velocity impact load greater than the load of the cylinder, the cylinder is opened so that the flow between the chambers through the holes can relieve pressure build-up in the second chamber. characterized in that it includes radial frangible flange means extending from said orifice means to said cap means to be effective for telescoping. : In Q d't M 'Ivy rln
``# 1r+!i W7 +-> Eve Ding 0 r old La] Book b /r'+ Good; Impact energy absorption device C
Leave it behind. 1jij fluid flow control means coupled to one of said cylinders for controlling fluid flow through said orifice means as said cylinder moves toward their telescoping position; adjustment rod means extending longitudinally within the device through the orifice means of the cap means, the frangible means of the orifice means extending radially to attach the orifice means to the aperture; opening said hole and increasing said chamber spacing by allowing movement of said orifice means from said hole and said cap means in response to an applied high velocity impact load greater than a minimum load applied; □ Collision characterized in that it includes assembled frangible flange means enabling telescopic collapsing of said cylinder so that said flow rate can relieve pressure build-up in said first chamber. Energy absorption device. 5. In the collision energy absorbing device according to claim 4. Additional bursting means are opened under a predetermined load condition in one of the chambers to hydraulically bypass said orifice means and said hole to relieve pressure buildup in said device. A collision energy absorbing device, characterized in that said cap means is equipped with said cap means. 6. In the collision energy absorbing device according to claim $1 or claim 2. Spring means of said device is operatively associated with said cylinder to move said cylinder relative C to a pre-extended position, and said cap means
- fixed to the end of the cylinder, said hole in said cap means providing a restricted flow path for fluid flow between said chambers under predetermined operating conditions to absorb impact energy; orifice means is operatively attached to said cap means to further restrict a fluid flow path between said chambers to absorb energy up to a predetermined energy level, said orifice means extending therethrough; a main body having a confined fluid flow path for retracting the main body and a predetermined build-up of fluid pressure in response to telescopic movement of said cylinder toward a retracted position to fracture said flange means and force said main body into said aperture. frangible flange means releasably retaining the main body within the bore so as to move the pressure fluid above the predetermined level and relieve the pressure of hydraulic pressure inside the device. Water bowl (
A collision energy absorbing device, characterized in that the energy present in the C is absorbed and passed through it to maintain the integrity of the device. 2. Special Feature 1 - In the collision energy absorbing device according to claim 6. An elongated slanted adjustment pin is connected to the outer end wall of the second cylinder of the cylinder and extends axially therefrom in the chamber to control the confined fluid flow of the main body of the orifice means. The device is moved toward the retracted position (gradually and further restricting the fluid flow path and thereby opening the first chamber under predetermined load conditions). a collision energy absorbing device for maintaining a constant pressure, wherein the fluid flow control means is predetermined, a buffer assembly is attached to the first cylinder or cylinders of the device; Suitable absorption device for increasing JJ sudden load load energy without each equipment.

Claims (1)

[Claims] 1. A collision energy absorbing device for loading a shock absorber assembly onto a support of a motor vehicle, comprising first and second cylinders mounted for telescopic movement between an extended position and a retracted position. wherein said first and second cylinders have stop means cooperating to establish an extended position of said cylinder, said first cylinder having a cap means at one end thereof and said first and second cylinders having said first and second cylinders having stop means cooperating to establish an extended position of said cylinder; and a second cylinder slidably disposed in said second cylinder to provide a second variable volume fluid chamber; a hole extending through said cap means; and a hydraulic fluid in a second chamber; fluid flow control means for controlling the flow of fluid from the second chamber into the second chamber in response to telescopic movement of the cylinder to the retracted position. , a driftwood flow control passageway for regulating fluid flow between the chambers as the cylinder moves toward the retracted position so that the fluid flow control means dissipates impact load energy to a predetermined magnitude; an impact energy absorbing device comprising orifice means operably disposed within said aperture of said cap means for providing said impact energy absorbing device, further comprising frangible means forming part of said orifice means, and said frangible means forming part of said orifice means; fluid force exceeding said frangible means and displaces said orifice means from said hole such that the fluid flow rate through said hole and the increased flow rate from said first chamber to said second chamber increases the pressure in said second chamber. characterized in that the device retains the orifice means in a removable manner to accommodate the energy of increasing impact loads without rupturing the cylinder. Collision energy absorption device. 2. The collision energy absorbing device according to claim 1, characterized in that a support means is supported on the first cylinder for the movement of the second cylinder with respect to the second cylinder. Device. 3,! 1+ A collision energy absorbing device according to claim 1 or 2, wherein the orifice means in the hole of the cap means comprises an annular orifice means for controlling the flow rate of fluid through the cap means; One said frangible means opens said hole in response to a high velocity impact load applied such that movement of said orifice means from said cap means is greater than a predetermined minimum load. a radial radial line extending from said orifice means to said cap means for being effective in enclosing said cylinder so that flow between the chambers may relieve pressure build-up in said first chamber; A collision energy absorbing insert characterized in that it includes frangible flange means. 4. The collision energy absorbing device according to claim 1 or 2, wherein the original flow rate control means is connected to one of the cylinders, and the cylinder is folded into the cylinder. including adjustment rod means extending longitudinally within the device through the orifice means of the cap means to control fluid flow rate through the orifice means as the cap means moves toward the position; said frangible means extending radially to attach said orifice means to said hole, said frangible means extending from said hole and said cap means in response to an applied high velocity impact load greater than a predetermined minimum load. to allow movement of the cylinder to open the hole and allow the cylinder to fold into the chamber so that increased flow between the chambers can relieve pressure build-up in the first chamber. A crash energy absorbing device characterized in that it includes assembled frangible flange means that enable. 5. A crash energy absorbing device as claimed in claim 4, wherein additional rupture means apply a predetermined load in one of said chambers to hydraulically bypass said orifice means and said hole. A collision energy absorbing device, characterized in that it is provided in said cap means to open under conditions and to relieve pressure buildup in said device. 6. A collision energy absorbing device as claimed in claim 1 or 2, wherein spring means of the device is operable with the cylinder to move the cylinder relative to the position of extension of the dog. said cap means being fixed to the end of said first cylinder, said hole in said cap means limiting the flow rate of driftwood between said chambers under predetermined operating conditions to absorb impact energy. a fluid flow path between the chambers, the orifice means being operatively attached to the cap means to further restrict the fluid flow path between the chambers for absorbing energy up to a predetermined energy level; said orifice means having a main body having a restricted fluid flow path therethrough, and a predetermined build-up of driftwood pressure responsive to retracting movement of said cylinder toward a retracted position fractures said flange means; and frangible flange means for removably retaining the main body within the bore so as to move the main body out of the bore and relieve hydraulic pressure within the apparatus. A collision energy absorption device, characterized in that energy at a level higher than a predetermined level is passed through it to absorb it, thereby maintaining the integrity of said device. 7. The collision energy absorbing device of claim 6, wherein an elongated slanted adjustment pin is connected to the wall of the outer end of the second of the cylinders and extends axially therefrom in the chamber. extending and extending through the restricted fluid flow path of the main body of the orifice means to gradually and more restrict the fluid flow path as the device moves toward the retracted position, thereby forming a predetermined A collision energy absorbing device characterized in that the pressure in the first chamber is kept constant under the load conditions. 8. In the collision energy absorbing device according to any one of claims 1 to 7, in order to absorb the collision force in an automobile application, a shock absorber assembly is provided as one or a pair of shock absorber assemblies in the first part of the device. 1. A collision energy absorbing device, characterized in that the second cylinder of each device is attached to the underframe of a vehicle chassis.