Bump stop

Bump stop for an amphibious vehicle suspension having a member selectively movable between an operating position, and an inoperative position. This allows the suspension to retract road wheels along locus for conversion to marine mode. Bump stop free end may be moved by filling cavities with pressurized fluid. Alternatively, the entire bump stop may be rotated on a pivot by a hydraulic cylinder, an electric solenoid, manually or by any other mechanical means. Alternatively, the movable member may be a position in a cylinder, withdrawn against a return spring by hydraulic pressure, and may act against resilient snubber on the vehicle suspension. Bump pad has a curved undersurface, allowing the bump stop to be bent out of the way when the suspension is lowered.

BACKGROUND OF THE INVENTION

The present invention relates to a bump stop and more particularly to a bump stop for the suspension of an amphibious vehicle.

An amphibious vehicle with a wheel retraction system requires a suspension bump stop in order to prevent excessive upward wheel travel movement when the vehicle is in land travel mode. However, when the wheels of the vehicle retract for marine mode, the bump stop should not interfere with the upward movement of the suspension.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided, a bump stop for an amphibious vehicle, the bump stop comprising a member having a stop portion for engagement with part of a vehicle suspension to limit travel of the suspension system relative to the vehicle body, in which the member is selectively movable between an operative position, in which the stop portion is deployed for engagement with the part of the vehicle suspension system, and an inoperative position, in which the stop portion is not deployed for engagement with the part of the vehicle suspension system, the bump stop further comprising means for moving the stop portion between the operative and inoperative positions.

In a first preferred arrangement the member is resilient and is provided with at least one internal cavity connected to a fluid supply line. Preferably the stop portion moving means is provided by pressurised fluid supplied to the internal cavity, which pressurised fluid expands the cavity of the resilient member causing the resilient member to distort.

In a second preferable arrangement, the member is resilient and is adapted to be pivotally mounted to a fixed part of the vehicle. In this arrangement, the stop portion moving means may be provided by a fluid operated cylinder, a piston of which is connected to the resilient member. Movement of the piston causes the resilient member to rotate about the pivotal mounting. Alternatively, the resilient member may be moved by an electrically operated solenoid or manually, or by any other appropriate mechanical or electrical means.

In a third preferable arrangement, the member is slidably mounted in a cylinder. One end of the member may be formed as a piston which is biased by a spring to move the stop portion of the member to the operative position. Preferably pressurised fluid causes the piston and member to retract into the cylinder, against the bias of the spring, to the inoperative position.

In accordance with a second aspect of the invention, there is provided an amphibious vehicle having a bump stop in accordance with the first aspect of the invention. In a preferred embodiment, the part of the vehicle suspension system which engages the member is resilient.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring firstly toFIG. 1, a first embodiment of a bump stop is indicated generally at10. The bump stop10comprises a resilient member12which is attached at one end13to a rigid base14, and has a free end16which forms a stop portion for contact with part of a vehicle suspension. The resilient member12is shaped substantially as a truncated cone or pyramid and is made of rubber, but may be made of any suitable resilient material. The base14is mounted to the structure24of a vehicle, seeFIG. 7.

A series of elongate internal cavities18are provided to one side of the resilient member12and are connected by a connecting cavity20. A fluid supply line22in the base14connects with the connecting cavity20for supplying pressurised fluid to the internal cavities18. As can be seen fromFIG. 2, when the internal cavities18are expanded by the force of pressurised fluid, the resilient member12distorts to one side, (to the right hand side as viewed).

Referring now toFIG. 7, a bump pad26is integrally formed with, or attached to a wheel support upright27of a suspension system of an amphibious vehicle. The resilient member12and rigid base14are mounted on the structure24of the vehicle in alignment with the bump pad26. The wheel support upright27is mounted between lower and upper control arms28,30which are pivotally mounted to the structure24of the vehicle in conventional manner. The wheel support upright27mounts a wheel29, also in conventional manner. The upper surface19of the bump pad26is cup shaped for receiving the end16of the bump stop10. Furthermore, the lower surface25of the bump pad26is formed as a smooth curve, the purpose of which will be described below. The wheel29is shown in the lowered position for use of the vehicle in a road mode and a retracted position in which the wheel is raised for use of the vehicle on water in a marine mode.

The operation of the bump stop10will now be described with reference toFIGS. 7 to 11. InFIGS. 7 & 8, the bump stop10is shown in an operative position, in which the resilient member12assumes its rest shape. The bump pad26is positioned below the end16of the resilient member12, and moves with the wheel support upright27relative to the vehicle body as the vehicle travels over land in road mode, as indicated by arrow A. The tip21of the bump pad26moves in an arc, as indicated by the dotted line23.

As can be seen fromFIG. 9, when the suspension system moves upwards relative to the vehicle in the direction indicated by arrow B, the cup shaped upper surface19of bump pad26contacts the end or stop portion16of the resilient member12. The resilient member12is compressed until the resilient member12prevents the pad26, and hence the wheel support upright27, wheel29and control arms28,30, from further relative upward movement.

The bump stop10can be selectively moved between the operative position and the inoperative positions by pumping pressurised fluid, for example hydraulic oil, water or air into or out from the fluid supply line22. As described with reference toFIG. 2, the pressurised fluid flows into the connecting cavity20and into the internal cavities18, which causes the cavities18to expand. The expansion of the cavities18forces the resilient member12to distort, and the end16of the resilient member12moves out of axial alignment with the base14in a direction away from the side of the internal cavities18.

Referring now toFIG. 10, when the amphibious vehicle has entered water and it is necessary to retract the suspension system, pressurised fluid is pumped into the cavities18, and the resilient member distorts as described above into the inoperative position. The end16of the resilient member12is now positioned away from the bump pad26, allowing the tip21of the bump pad to move past the resilient member12, as indicated by arrow C, so that the wheel can be moved to the retracted position. When the bump pad26has moved past the bump stop10to the retracted position, release of the pressurised fluid allows the resilient member12to assume its rest or operative shape.

When it is required to deploy or lower the suspension system for land travel mode from the retracted position, the wheel support upright27moves downwards as indicated by arrow D inFIG. 11. As the tip21of the bump pad26follows the arc23, shown in dotted outline, the underside25of the bump pad26contacts the resilient member12and forces the resilient member to distort towards the inoperative position. Consequently, the bump pad26is able to move past the bump stop10in the downward direction without need for supplying pressurised fluid to the cavities18. The fluid control circuit (not shown) is therefore simpler than the circuit would be if the pressurised fluid had to be supplied for movement of the bump stop10during wheel deployment.

A second embodiment of a bump stop in accordance with the invention will now be described with reference toFIGS. 3 and 4. The bump stop is indicated generally at40, and comprises a resilient member42which is attached at one end43to a support member44, and has a free end46which forms a stop portion. The resilient member42is shaped substantially as a truncated cone or pyramid and is made of rubber, but may be made of any suitable resilient material. The support member44is pivotally mounted48to a rigid base50, which is mounted to the structure24of a vehicle, seeFIG. 7, as in the previous embodiment described.

A fluid operated cylinder52is mounted to one side of the base50, and comprises a single port53, a piston54, a piston rod56and a spring58. An end60of the piston rod56is pivotally mounted62to the support member44. The spring58is positioned between a back wall64of the cylinder52and the piston54, and biases the piston54and piston rod56to an extended position. Pressurised fluid supplied to the cylinder52through the port53acts against the piston54and the bias of the spring58to retract the piston rod56into the cylinder52.

In operation, when no pressurised fluid is supplied to the cylinder52, the piston rod56is extended, and the resilient member42is in the operative position, shown inFIG. 3. When it is desired to retract the suspension system of the vehicle, pressurised fluid is supplied to the cylinder52and the piston rod retracts as described. This causes the support member44to rotate about the pivotal mounting48and moves the end46of the resilient member42out of the path of the bump pad26, to the position shown inFIG. 4. As in the previous embodiment described, when the suspension system is deployed to road mode from the retracted position in marine mode, the underside25of the bump pad26forces the resilient member12to one side.

FIGS. 5 & 6show a modification to the second embodiment in which the fluid operated cylinder52is replaced by a double acting electric solenoid152. Parts in common with those shown inFIGS. 3 & 4are given the same reference numerals.

The solenoid152has coils153and155, a yoke154, rod156, and electrical connections157. The yoke154is connected to the support member44by the rod156. Preferably, the solenoid is a latching solenoid. Depending on the electrical signals fed to the coils, the bump stop can be moved between the operative position shown inFIG. 5and the inoperative position shown inFIG. 6.

Rather than a double acting solenoid, a single acting solenoid could be used, rendered reversible by changing the polarity.

A third embodiment of a bump stop in accordance with the invention will now be described with reference toFIG. 12. The bump stop, indicated generally at70, comprises a member72slidably mounted in a cylinder74. A piston76is formed at one end of the member72and is located in a piston chamber77within the cylinder74. A spring78, which locates in an internal recess79of the member72and engages an end cap80of the cylinder74, biases the member72out of the cylinder to the operative position. The other end of the member72extends out of the cylinder74in the operative position and is formed as a latch82, having a flat lower surface84which forms a stop portion, and a curved upper surface86.

A pressure fitting88is provided in the cylinder74, in communication with a port90, which opens into the piston chamber77. Pressurised fluid supplied to the fitting88enters the chamber77and causes the piston76and consequently the member72to move to the right, as viewed, against the action of the spring78. Seals92seal between the piston76and the internal wall of the cylinder74, and seals94seal between the member72and the internal wall of the cylinder74. The member72including the latch82can therefore be drawn into the cylinder74, which is the inoperative position. When the pressure of the fluid is relieved, the bias of the spring extends the member72to the operative position. The cylinder74is mounted to the vehicle body.

In this arrangement, the member72is not resilient, and therefore a resilient snubber93is attached to the cup shaped upper surface19of the bump pad26.

In operation, the member72is biased out of the cylinder74by the spring78in operational mode, and the latch82is positioned in the path of the bump pad26. As in the previous arrangements, the bump pad26moves in an arc, and the path of the tip21is indicated by the dotted line23. The wheel support upright27and the bump pad26are prevented from moving upwards past the latch82of the member72, because the bump pad26and snubber93engage the flat surface84of the latch82, and limit the upward movement.

When it is desired to retract the wheels for marine mode, pressurised fluid is supplied through the port90, which causes the piston76and the member72to retract by sliding into the cylinder74, against the bias of the spring78, to the inoperative position. The latch82is contained in the cylinder74and allows the bump pad26with snubber93to pass to the retracted position. Relief of the fluid pressure allows the bias of the spring78to push the member72and latch82from the inoperative position to the operative position.

When the suspension moves back towards the road mode position from the retracted marine mode position, the smooth curved underside25of the bump pad26frictionally engages the upper curved surface86of the latch82, and pushes the latch82and member72into the cylinder against the bias of the spring78.

In all of the embodiments it should be noted that if the pressurised fluid supply to the bump stop10,40,70fails, then the bump stop is always resiliently deployed to the operative position. Furthermore, the suspension system can always be deployed to road mode because in the movement of the bump pad from the retracted to the deployed position, the member is moved to one side by frictional engagement.

In other arrangements (not shown), the member may be moved manually, or by any other appropriate mechanical or electrical means.