GB2084944A - Retractable bumpers for vehicles - Google Patents

Abstract

A vehicle fitted with a bumper 2 arranged to yield on impact and return to or towards its initial position after removal of the impacting force, is fitted with selectively operable double-acting hydraulic jacks 8 for retracting the bumper to a parked position so as to reduce the overall length of the vehicle and enable it to occupy less space when parked or being shipped. On impact the jacks are freely motored, or their closure may be restricted so as to absorb impact energy. Bumper 2 is carried by parallel member 4 fitted with rollers 5 which run in tracks 6 on chassis members 7. <IMAGE>

Description

SPECIFICATION Improvements relating to bumpers for vehicles This invention relates to bumpers for vehicles, more particularly to bumpers and like protective devices (hereinafter called bumpers) which are intended to yield on impact so as to absorb or dissipate at least some of the impact energy in a collision and, subsequently, to return to or towards their original positions on the vehicles so as to be ready to give protection in a further impact. Such bumpers, particularly front bumpers, usually project from the main body of the vehicle so increasing the length of the vehicle to allow for yielding travel of the bumper on impact.

The present invention consists in a vehicle fitted with a bumper which is adapted to yield on impact and return to or towards its original position when an impacting load is removed, and a retracting mechanism comprising selectively operable power operated means connected between the bumper and a structural part of the vehicle relative to which the bumper moves on impact and which power operated means, on operation, causes the bumper to be retracted from a normal forward or rearward extending position whereby the overall length of the vehicle is reduced.

The power operated means may be arranged to retract and hold the bumper in a parked position so as to reduce the length of the vehicle for parking and carriage, for example on a ship.

The locus of the bumper may be controlied by co-operating guide means connected between the bumper and a structural part of the vehicle, which means also guide movement of the bumper on impact.

The invention further consists in a vehicle bumper and retracting mechanism in which the retracting mechanism is adapted for connection to a structural part of a vehicle and comprises features as set out hereinbefore.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a side elevation of the front of a vehicle, Figure 2 is a perspective view of a bumper showing its connection to the vehicle, and Figure 3 is an hydraulic circuit diagram.

Referring to Figure 1, a vehicle 1 is fitted with a front bumper 2 which is mounted so that it can move between a normal position of use as shown in full lines at 'A' to the yield position shown in broken lines at 'C' on impact. An intermediate "parked" position is shown in broken lines at 'B'.

Referring now to Figure 2, the bumper 2 has brackets 3 to which elongated members 4 are connected. The members 4 are parallel and extend axially of the vehicle. Each member 4 has a roller assembly 5 secured to its inner face. Each roller assembly engages in a track 6 which is secured to an axially extending chassis member 7 of the vehicle so as to guide movement of the bumper.

A double-acting hydraulic jack 8 is pivotally connected between each elongated member 4 and the adjacent chassis member 7. In normal operation of the bumper the jacks may be freely motored during movement of the bumper. The jacks may be partially closed to bring the bumper to the "parked" position.

Referring now to Figure 3, each jacks 8 has a piston 9 to which a piston rod 11 is connected so as to define a full area chamber 12 and an annular area chamber 13 of the jack. Conduits 14, 1 5 connect the chambers 12 to a port 1 6 of a selector valve 1 7 by way of a one-way restrictor generally shown at 1 8 and comprising a check valve 19 and a restrictor 21.

Conduits 22, 23, 24 connect the annular chambers 13 to a port 25 of the selector valve 1 7.

A displacement cylinder 26 contains a piston 27 slideable therein and which is biased to one end of the cylinder by a spring 28. The piston 27 has stops 29 which limit its movement to the other end of the cylinder. The spring end of the cylinder 26 is connected to conduit 23 whereby it is also in communication with conduit 24. The piston end of cylinder 26 is connected by a conduit 31 to a port 32 of the selector valve 17.

An hydraulic pump 33, for example driven by an electric motor, draws hydraulic fluid from a tank 34 and delivers it through a conduit 35 to a port 36 of the selector valve 1 7. The pump is provided with a pressure relief valve, not shown. A conduit 37 connects a port 38 of the selector valve 1 7 to the tank 34.

The selector valve 1 7 can be operated, for example manually or electrically, to effect two combinations of port connections of the valve.

These are shown at 17(1) and 17(2) respectively.

In normal operation the selector valve connections are as shown at 17(1) in which ports 16, 25 and 32 are connected together and are connected to the tank by way of the port 38. The hydraulic pump is not running and port 36 is sealed. If the bumper receives an impact the pistons 9 and piston rods 11 will be caused to move into the cylinders of the jacks, expelling fluid from the chambers 12 and expanding the chambers 13. Fluid expelled from chambers 12 is forced to pass through the restrictor 21 so dissipating some of the impact energy. The fluid passes into the selector valve 17 at port 1 6 whence some of the fluid flows into the expanding chambers 13 through conduits 24, 23 to keep them filled and the surplus is returned to the tank 34.After impact the bumper returns to or towards its original position, as A in Figure 1, and its restoring force draws the pistons 9 and rods 11 outwardly. Fluid is expelled from the chambers 1 3 to the port 25 of the selector valve 1 7 whence it flows into the expanding chambers 12 of the jacks, by way of the check valve 1 9 and the restrictor 21 in parallel, the additional fluid required to fill these chambers being drawn from the tank 34. If it is not desired to dissipate any impact energy in the hydraulic system the oneway restrictor 1 8 may be omitted.

As described, the hydraulic system allows the bumper to move under impact and it dissipates some of the impact energy. It is not a primary function of this system, however, to absorb or dissipate the impact energy, and it does not return the bumper to or towards its normal position after impact. Other means, not shown, of any known suitable kind are provided specifically to perform those functions. Nevertheless, if desired, it may be possible to modify the hydraulic system to perform additionally at least some of the abovementioned functions.

When it is desired to retract the bumper 2 to the "parked" position, as B in Figure 1 , the selector valve 1 7 is operated to effect the connections shown at 17(2). This operation may simultaneously switch on an electric motor to drive the pump 33 which then delivers fluid under pressure through conduit 35, port 36, check valve 39, port 32 and conduit 31 to drive the piston 27 to the spring end of the cylinder 26 so that the stops 29 engage that end of the cylinder. Port 25 in the selector valve 1 7 is caused to be sealed by a check valve 41 so that the fluid expelled from the spring end of the cylinder 26 is forced into the chambers 13 causing the pistons 9 and rods 11 to move inwardiy and draw the bumper 2 to the "parked" position.The fluid expelled from chambers 12 passes to the tank 34. A pressure operated switch, not shown, connected to conduit 35 causes the electric motor to cut out and stop the pump when a predetermined pressure is attained, being a pressure sufficient to retract the bumper. This pressure is retained by the check valves 39,41.

Alternatively the piston 27 can be arranged to operate a micro-switch (not shown) when it reaches the end of its travel and so cut out the electric motor. in either case if, due to fluid leakage, the pressure falls, or the piston 27 moves away from the spring end of the cylinder, provision can be made for the motor to re-start automatically so that the bumper is returned to and retained in the "parked" position. Any thermal expansion of the fluid which may occur whilst the bumper is in the "parked" position is accommodated by a slight further retraction of the bumper 2.

The expelled fluid volume of the spring side of the cylinder 26 is designed to be such as to displace the pistons 9 and rods 11 the distance required to retract the bumper 2 to the "parked" position.

When it is desired to release the bumper 2 from the "parked" position the selector valve 17 is operated to revert the connections to those shown at 17(1). The restoring energy in the bumper 2 causes the pistons 9 and rods 11 to be drawn out thereby expelling fluid from chambers 13. The release of pressure from conduit 31 allows the spring 28 to move the piston 27 back to its original position in the cylinder 26. Fluid from chambers 13 goes back into the spring end of the cylinder 26 and the chambers 1 2 are refilled from the tank 34. The tank 34 is preferably positioned above the level of the jacks and cylinder 26 so that these are kept filled by a gravity head. Preferably the pump 33 is also below the tank 34 so that it is kept primed.

If desired the restrictor 21 could be replaced by a relief valve. The effect of this would be to restrict yield of the bumper, when impacted, until pressure had built-up to a value causing the relief valve to lift and, after lifting, impact energy would be dissipated across it. A by-pass valve, in parallel with the relief valve and operated, for example, electrically, would be desirable to reduce power requirements for the pump when retracting the bumper. The by-pass valve could be actuated simultaneously with energisation of an electric motor for driving the pump.

Claims (14)

1. A vehicle fitted with a bumper which is adapted to yield on impact and return to or towards its original position when an impacting load is removed, and a retracting mechanism comprising selectively operable power operated means connected between the bumper and a structural part of the vehicle reiative to which the bumper moves on impact and which power operated means, on operation, causes the bumper to be retracted from a normal forward or rearward extending position whereby the overall length of the vehicle is reduced.

2. A vehicle as claimed in claim 1 wherein the power operated means is arranged to retract and hold the bumper in a parked position in which the overall length of the vehicle is reduced.

3. A vehicle as claimed in claim 1 or claim 2 wherein co-operating guide means are connected between the bumper and the structural part of the vehicle, which means guide movement of the bumper on impact and movement of the bumper on retraction.

4. A vehicle as claimed in any preceding claim wherein the selectively operable power operated means comprises hydraulic jack means operatively connected between the bumper and the structural part of the vehicle, a source of hydraulic pressure fluid, and means connecting said source to the hydraulic jack means including control valve means selectively operable to cause retraction of the bumper by the source.

5. A vehicle as claimed in claim 4 wherein the hydraulic jack means comprises at least one double acting hydraulic jack having two jack chambers separated by a piston, one of which jack chambers contracts and the other expands when the bumper is subjected to impact.

6. A vehicle as claimed in claim 5 wherein the hydraulic jack or jacks are operated to retract the bumper by displacement of a volume of fluid into the jack or jacks by displacement means operated by the source.

7. A vehicle as claimed in claim 6 wherein the displacement means comprises a container and movable means dividing said container into two displacement chambers one of which is connected to the jack or jacks and the other of which is connectable to the source through the control valve means.

8. A vehicle as claimed in claim 7 in which the movable dividing means is biased so that the displacement chamber connectable to the source is of its minimum size when connected through the control valve to exhaust and disconnected from the source.

9. A vehicle as claimed in claim 7 or claim 8 in which the container comprises a cylinder and the movable dividing means comprises a piston slidable in the cylinder.

10. A vehicle as claimed in any of claims 5 to 9 wherein the or each jack chamber of the hydraulic jack means which contracts when the bumper is subjected to impact is connected to exhaust through energy dissipating means whereby at least some impact energy is dissipated in the hydraulic fluid.

11. A vehicle as claimed in claim 10 in which the energy dissipating means comprises a restrictor.

12. A vehicle as claimed in claim 10 in which the energy dissipating means comprises a relief valve.

13. A vehicle substantially as described herein with reference to the accompanying drawings.

14. A vehicle bumper and retracting mechanism wherein the retracting mechanism is adapted for connection to a structural part of a vehicle and comprises features as set out in any one of claims 1 to 12.

1 5. A vehicle bumper and retracting mechanism substantially as described herein with reference to the accompanying drawings.