GB2397344A

GB2397344A - Retractable suspension actuator locking

Info

Publication number: GB2397344A
Application number: GB0400826A
Authority: GB
Inventors: Adam Ruddle
Original assignee: Gibbs Technologies Ltd
Current assignee: Gibbs Technologies Ltd
Priority date: 2003-01-17
Filing date: 2004-01-15
Publication date: 2004-07-21
Anticipated expiration: 2024-01-15
Also published as: GB2397344B; GB0400826D0; GB0301095D0

Abstract

An amphibious vehicle has a retractable suspension where at least one wheel may be retracted and deployed by a fluid strut 40 with a piston 42. If the vehicle is stored, a gradual loss of fluid pressure may occur, allowing grounding. Stop means 76 prevents this by limiting piston movement to a predetermined range. The stop means may also act to prevent wheel droop once the wheel is retracted. Locking pin 80 is contained within housing 78 and biased into chamber 48 by spring 82. When the wheel is to be retracted, a solenoid or fluid actuator is energized to withdraw the pin. The pin is released once the piston has passed the pin. Pin actuation may be automatic or semi-automatic; and may be linked into a vehicle mode change control system using sensors to determine when the vehicle enters and leaves water. The strut also provides suspension damping.

Description

Amphibious Vehicle The present invention relates to an amphibious vehicle

and in particular to such a vehicle having an actuator for moving a wheel of an amphibious vehicle between a land support position and a retracted position.

It is known to retract the wheels of an amphibious vehicle to move them above the waterline when the vehicle is used on water. US patent 5,531, 179 describes an apparatus for retracting an axle driven wheel upwardly and inwardly so that it is received in an upper compartment positioned above the water line. An actuator in the form of a double acting hydraulic ram is used to provide the motive force for moving the wheel between the retracted position and an extended position in which the wheel is able to support the vehicle on land. US patent 5,590,617 describes another arrangement for retracting the wheels of an amphibious vehicle, in which a double acting pneumatic ram is used to provide the motive force for moving the wheel between its retracted and extended positions.

A problem with fluid rams such as those used in the above described wheel retraction systems is that they can be prone to leakage over time and/or to failure to pressurize. Such problems have also been known to occur with hydro-pneumatic suspension systems used on conventional cars which can fall over time due to fluid loss. However, the travel of the suspension units used on amphibious vehicles in which the wheels can be retracted is usually much greater than that of suspension units in a conventional vehicle. As a result, there is a risk that the hull of an amphibious vehicle will contact the ground if the fluid system should fail or leak over time when the wheels are extended. This may be a problem, for example, if the vehicle is stored over winter without the engine being started to pressurize the system and could result in the hull or keel of the vehicle being damaged by contact with the ground. The problem is compounded by the fact that in many amphibious vehicles the hull and/or keel are made from fibre glass or a similar material which is more easily distorted than the steel body and chassis of a conventional road vehicle.

Similarly, when the vehicle is being used on water, there is a risk that the wheels may move from the retracted position to the ground support position if the fluid system should fail or leak. The deployment of a wheel or wheels in this way would increase hull drag if the vehicle is travelling at speed at the time.

In US 5,590,617 this problem is tackled by providing a secondary locking system for the suspension. The secondary locking system comprises slats that are pivotably attached at one end to a housing on part of the suspension of a respective wheel. The other end of the slats slide through a housing attached to the body of the vehicle. A locking pin which is movable by means of a double acting pneumatic ram is positioned to extend through holes in the housing attached to the body. Apertures are provided in the slats which align with the holes in the housing when the wheels are either fully extended or fully retracted. When the suspension is in either the fully extended or the fully retracted position the locking pin is pushed through the holes in the housing and the aligned holes in the slats to lock the suspension In position.

The arrangement described in US 5, 590,617 has a number of drawbacks. The slats are heavy and bulky and so add to the overall weight of the vehicle and are difficult to package. The slats are also liable to damage through corrosion or through ingress of foreign objects. As the mechanism is dependent on a pin fitting through aligned holes, satisfactory operation requires perfect alignment being maintained between several diverse components. This requires close tolerancing during manufacture and continual maintenance, adding to the cost of manufacturing and maintaining the vehicle.

It is an objective of the present invention to provide an amphibious vehicle having an improved actuator which overcomes, or at least mitigates, the problems ofthe known wheel retraction systems.

In accordance with a first aspect of the invention, there is provided an amphibious vehicle having at least one wheel movable between a land support position and a retracted position, and an actuator comprising a cylinder and a piston located within the cylinder, the piston and cylinder being moveable relative to each other under the influence of a pressurized fluid to move the wheel between the land support position and the retracted position, in which the actuator includes a stop means having a stop member selectively deployable to limit movement of the piston relative to the cylinder to a predetermined range that is less than the full range of relative movement between the piston and the cylinder, the vehicle further comprising control means for remotely controlling deployment of the stop means.

In an amphibious vehicle in accordance with the invention, the stop means can be deployed when the wheel is in the land support position to prevent the wheel from unintentionally moving towards the retracted position due to a leakage of fluid in the actuator. When it is intended to retract the wheel, the stop means is withdrawn so that the piston can move relative to the cylinder over its full stroke. Preferably, the stop means can also be arranged to be deployed when the wheel is in the retracted position, to prevent the wheel moving from the retracted position to the land support position unintentionally.

An amphibious vehicle in accordance with the invention provides a solution to the problems of the prior art wheel retraction arrangements that is compact, relatively simple to manufacture, reliable and durable.

Preferably, the stop means comprises a pin mounted to a wall of the cylinder, the pin being selectively movable from a first position in which it projects into the cylinder for contact with the piston and a second position in which it is withdrawn from the cylinder. In a particularly preferred embodiment, the pin is arranged to pass through the cylinder wall when in the first position.

Advantageously, the stop pin is biased by a resilient means into the first position.

Preferably, the stop means comprises actuation means for controlling movement of the stop pin between the first position and the second position. The actuation means may be an electrical solenoid or it may comprise an hydraulic or pneumatic actuation means. Preferably, the actuation means is mounted to the actuator externally of the cylinder wall, with the pin being arranged to project through the cylinder wall into the path of the piston when in the first position.

In an alternative embodiment, the stop means comprises a stop member mounted to the piston or to a linkage connected to the piston for movement between a first position in which it can contact a corresponding stop means associated with the cylinder to limit movement of the piston relative to the cylinder to the predetermined range, and a second position in which it is not arranged for contact with the corresponding stop means.

The actuator may be a double acting hydraulic ram that is configured such that it also provides suspension and/or damping for the at least one wheel when the wheel is in the land support position. Several embodiments of an actuator of this type are disclosed in the applicant's co-pending International patent application published under No. WO 01/74612 Al which is hereby incorporated by reference in its entirety.

Preferably, the control means is arranged to automatically control deployment of the stop means.

Preferably, the control means is arranged to withdraw the stop means from the deployed position to enable the at least one wheel to be moved between the land support and retracted positions. More preferably, the arrangement is such that the stop means is normally deployed when the at least one wheel is in the land support position or the retracted position, the control means being adapted to withdraw the stop means from the deployed position only when the at least one wheel is to be moved between the land support and retracted positions.

Advantageously, the control means is arranged to automatically withdraw the stop member from its deployed position when the vehicle converts between a land use mode and a water borne mode.

An embodiment of the present invention will now be described, by way of example only, with reference to the following drawings in which: Figure 1 is a simplified perspective view of one embodiment of a wheel redaction apparatus for an amphibious vehicle shown in the land support position and incorporating an actuator in accordance with the invention; Figure 2 is a schematic cross-sectional view of the actuator of Figure 1, showing the actuator extended and the stop means deployed, and, Figure 3 is a view similar to that of Figure 2 but showing the actuator in a retracted position with the stop means withdrawn.

Figure 1 shows a wheel redaction apparatus 10 for an amphibious vehicle. The wheel retraction apparatus is similar to that described in US patent 5,531,179, to which the reader should refer for a detailed description of its construction and operation. The contents of US patent 5,531,179 being hereby incorporated in its entirety by reference.

Briefly, the apparatus 10 comprises a wheel support upright 12 mounted to the body 14 of an amphibious vehicle by means of an upper suspension arm 16 and a lower suspension arm 18, in a manner well known in the art. A drive shaft 20 for transmitting drive from an output 22 of a differential extends through a sealed opening 23 in the body of the vehicle. The outer end of the drive shaft comprises a constant velocity (CV) joint 24 which is received in a housing at the lower end of the wheel support upright. A stub shaft 26 of the CV joint projects from the housing for supporting an associated wheel (not shown) in a manner well known in the automotive art.

The lower suspension arm 18 is pivotably connected to the body of the vehicle by means of two inboard pivots 28. One end of a torsion bar 30 is rotationally fast with one of the inboard pivots of the lower suspension arm, whilst the other end of the torsion bar is rotationally fast with a first end of a lever or actuation arm 32. The other end of the lever 32 is connected to a lower end of an actuator 34 by means of a pivot joint 36. An upper end of the actuator is pivotably connected to the body 14 of the vehicle by means of a further pivot joint 38.

The actuator 34 is in the form of a double acting hydraulic ram which can be redacted or extended, as will be described in more detail later. The arrangement is such that retracting or extending the actuator rotates the lever 32, which in turn rotates the torsion bar 30 and the lower suspension arm 18 to move the wheel between the land support position and the retracted position. For a more detailed description of the operation of the retraction apparatus the reader should refer to the previously identified US patent application 5, 531,179.

In the presently preferred embodiment, the actuator 34 is adapted to provide suspension and/or damping for the associated wheel when the wheel is in the land support position, in accordance with the principles set out in the applicant's co-pending International patent application WO 01/74612 Al to which the reader should refer for further details.

With reference to Figures 2 and 3, the actuator 34 comprises a cylinder 40 and piston 42 moveable axially within the cylinder and sealingly engaging the inner walls of the cylinder. i A linkage rod 44 is attached to one face of the piston 42 and extends through a sealed aperture 46 in the base of the cylinder. The linkage rod 44 terminates at the end remote from the piston in a mount 47 by means of which the rod can be pivotably connected to the lever arm 32.

The piston 42 defines first and second chambers 48, 50 in the cylinder 40. A seal 52 is provided on the circumference of the piston 42. The first and second chambers 48, 50 are filled with hydraulic fluid.

A hydraulic line 54 leaves the cylinder 40 from a port 58 in the side wall of the cylinder 40 close to the base 41 thereof and connects to a gas charged hydraulic accumulator 60 and to the hydraulic system ofthe vehicle, which system includes a source of hydraulic pressure and a hydraulic fluid reservoir (not shown).

A hydraulic transfer line 62 is provided external to the cylinder 40 and connects first and second ports 64, 66 in the side wall of the cylinder. The first port 64 is located in the side wall close to the base of the cylinder 40, whilst the second port 66 is located in the side wall at approximately the mid-point of the cylinder 40. A first on/off valve 68 is provided in the transfer line 62.

In an alternative embodiment, the first port 64 could be provided in the end wall at the base of the cylinder.

A further hydraulic line 70 extends from a port 72 in the upper wall of the cylinder 40 and is controlled by a second on/off valve 74. The further line 70 is connected to the hydraulic system of the vehicle.

The actuator 34 is shown in Figure 2 in an extended, road travel mode for use when the associated wheel is in the land support position. In this mode, the first on/off valve 68 in the transfer line 62 is open allowing a restricted flow of fluid between the first and second chambers and the second on/off valve 74 in the top line 70 is closed. With valves in this configuration, the piston is able to move vertically relative to the cylinder to accommodate normal suspension movement of the associated wheel over a reduced stroke. The maximum upward travel of the piston being shown in chain dotting. When the piston 42 is in the position shown in chain dot, the port 66 is closed by the piston 42 and further movement of the piston upwards in the cylinder is prevented by the volume of hydraulic fluid in the first chamber 48, thus providing a hydraulic bump stop. Movement of the piston 42 in the vertically downwards direction is limited by engagement of the lower face of the piston 42 with the inner surface of the base 41 of the cylinder 40.

In use when the actuator is in road travel mode, as the associated wheel encounters irregularities in the road surface on which the vehicle is being driven, the piston 42 moves axially within the cylinder 40 within its reduced stroke. As the vehicle moves over, in particular, rough terrain, excessive oscillation of the vehicle is obviated because of the damping effect of the actuator and the gas charged hydraulic accumulator 60.

As discussed above, under normal operating conditions when the actuator is in road mode, the upward movement of the piston 42 relative to the cylinder 40 is limited by the hydraulic bump stop. However, in the event of a fluid leakage, resulting in a loss of fluid pressure in the first chamber 48, it would be possible for the piston 42 to move upwardly beyond the level of the port 66 resulting in the body of the vehicle drooping as the associated wheel moves toward the retracted position. To prevent this happening, the actuator 34 is provided with a stop means indicated generally at 76.

The stop means 76 comprises a housing 78 attached to the side wall of the cylinder which accommodates a hollow pin or peg 80. The pin 80 is biased into the cylinder by means of a compression spring 82 operative between an inner surface ofthe closed end 84 ofthe pin and the housing. The housing also accommodates an electric solenoid that is connected to a source of electrical current by means of wires 86,88. The arrangement is such that when the solenoid is activated, the pin 80 is withdrawn into the housing as is illustrated in Figure 3.

When the wheel is in the land support position as shown in Figure 2, the solenoid can be de- activated so that the spring 82 biases the pin 80 into the first chamber 48 of the cylinder above the piston. With the pin 80 deployed in this way, it provides a mechanical stop that can be contacted by the piston to prevent the piston 42 from moving upwardly relative to the cylinder 40 over its full stroke, in the event of a loss of fluid pressure in the first chamber 48. This ensures that the body of the vehicle will not droop fully and so preventing the hull or the keel contacting the ground and being damaged due to a loss of fluid pressure in the system.

The stop means 76 is arranged so that the pin 80 is positioned slightly above the level of the second port 66. This ensures that the piston does not contact the pin 80 during normal use of the vehicle in land use mode, where the upward movement of the piston 42 is limited by the hydraulic bump stop.

When it is desired to retract the wheels of the vehicle, the pin 80 can be withdrawn by activating the solenoid as is illustrated in Figure 3. With the pin 80 withdrawn from the cylinder 40, the piston 42 is able to move over its full stroke relative to the cylinder enabling the wheels to be retracted. As is described in more detail in WO/0174612A1, in order to retract the associated wheel, the first on/off valve 68 in the transfer line 62 is closed and the second on/off valve 74 in the top line 70 is opened to connect the first chamber 48 to the hydraulic fluid reservoir. In this condition, the strut can now act as a hydraulic actuator and may be used to retract the wheel beyond its normal travel by means of pressurized fluid being pumped into the second chamber 50 whilst the fluid in the first chamber 48 is exhausted through the upper port 72.

When the associated wheel is fully retracted, the lower surface of the piston 42 is above the pin 80. If the solenoid is now deactivated, the pin 80 will be deployed within the cylinder below the piston 42 and so can act as a stop to prevent the associated wheel moving to the land support position in the event of a loss of fluid pressure in the second chamber 50. In practice, some piston travel may be allowed before the piston contacts the pin.

To return the wheel to the land support position, the stop pin 80 is withdrawn from the cylinder 40 by activating the solenoid and the actuator operated in reverse with pressurized fluid being pumped into the first chamber 48 through the upper port 72 and exhausted from the second chamber 50. Once the piston 34 has moved to a position below the second port 66, the valve 74 can be closed and the valve 68 opened so that the strut can again provide suspension and damping for the wheel, and the solenoid is deactivated to deploy the stop pin in the first chamber 48 of the cylinder.

The pin 80 will normally be deployed when the wheel is in either the land support position or the retracted position and is only withdrawn when it is necessary to move the wheel between these two positions, for example to convert the vehicle from land use mode to water borne mode or vice versa.

In a preferred embodiment, the stop pin 80 is circular in cross section, however any shape of pin or peg 80, whether hollow or not, can be used. Furthermore, whilst an electric solenoid is the preferred method for withdrawing the pin 80 from the cylinder, this is not essential and any suitable method can be used. For example, the pin 80 can be withdrawn using an hydraulic or a pneumatic actuator as will be readily understood by those skilled in the art.

Whichever method is used, it is preferred that the stop means 76 be arranged so that the pin is normally deployed within the cylinder 40 so that the arrangement is failsafe.

Operation ofthe stop means 76 is remotely controlled by a control means (not shown), which may include a programmable processing means. The control means may initiate withdrawal or deployment of the stop member semi-automatically in response to an input from a driver or operator of the vehicle. In particular, the control means may be adapted to regulate the deployment of the stop pin 80 as part of a procedure to convert the vehicle between land mode and water borne mode of uses. This conversion procedure could be initiated semi- automatically in response to an input from a driver or operator of the vehicle requesting a change of mode. Alternatively, the control means may initiate a change of mode fully automatically. For example, sensor means may be provided to determine when the vehicle has entered a body of water and that it is safe to retract the wheels. The control means operating in response to an output from the sensor means to retract the wheels, controls the deployment ofthe stop pin 80 as part ofthe wheel retraction process. Such control and sensor means are described in the applicant's co-pending International patent application published as WO 03/04571 6 and which claims priority from UK Patent applicationNo. GB 0128338.1.

Although it is preferred that the stop means comprises a pin retractably mounted to the wall of the cylinder 40 for contact with the piston 42, other arrangements could also be used. For example, a stop member may be mounted to the piston 42 or to the linkage 44 for movement between a first deployed position in which it contacts a corresponding stop member mounted to the cylinder 40 (or with the cylinder itself) to limit movement of piston 42 relative to the cylinder 40, and a second, non- deployed, position in which it does not contact the stop member or the cylinder 40 such that the piston 42 can move over its full range of movement relative to the cylinder 40.

Whilst the invention has been described above in relation to a hydraulic actuator in accordance with one of the embodiments disclosed in WO/01i4612A1, it should be understood that the invention can be applied to an actuator in accordance with any of the embodiments disclosed therein. Furthermore, it should be understood that the invention is not limited to application on hydraulic actuators adapted to provide suspension and/or damping for the associated wheel in accordance with WO 01/74612A1, but can be applied to any suitable actuator whether hydraulic or pneumatic, powered by any suitable liquid or gas, or a combination thereof. For example, the invention could be applied to an actuator in the form of a simple double acting hydraulic or pneumatic tarn. In particular, the invention could be applied to the pneumatic actuators disclosed in US 5,590,617 in place of the secondary locking system as will be readily understood by those skilled in the art.

It should also be understood that the inventive actuator is not limited to application with the wheel retraction apparatus as shown in Figure l, but rather can be applied to any suitable l O wheel retraction apparatus.

Whereas the invention has been described in relation to what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed arrangements but rather is intended to cover various modifications and equivalent constructions included within the scope of the invention as defined by the 1 5 claims.

Claims

Claims 1. An amphibious vehicle having at least one wheel movable between

a land support position and a retracted position, and an actuator comprising a cylinder and a piston located within the cylinder, the piston and cylinder being moveable relative to each other under the influence of a pressurized fluid to move the wheel between the land support position and the retracted position, in which the actuator includes a stop means having a stop member selectively deployable to limit movement of the piston relative to the cylinder to a predetermined range that is less than the full range of relative movement between the piston and the cylinder, the vehicle further comprising control means for remotely controlling deployment of the stop means.
2. An amphibious vehicle as claimed in claim 1, in which the stop means comprises a pin mounted to a wall of the cylinder, the pin being selectively movable from a first position in which it projects into the cylinder for contact with the piston and a second position in which it is withdrawn from the cylinder.
3. An amphibious vehicle as claimed in claim 2, in which the pin is arranged to pass through the cylinder wall when in the first position.
4. An amphibious vehicle as claimed in claim 2 or claim 3, in which the stop pin is biased by a resilient means into the first position.
5. An amphibious vehicle as claimed in any one of claims 2 to 4, in which the stop means comprises actuation means for controlling movement of the stop pin between the first position and the second position.
6. An amphibious vehicle as claimed in claim 5, in which the actuation means is an electrical solenoid.
7. An amphibious vehicle as claimed in claim 5 in which the actuation means comprises an hydraulic or pneumatic actuation means.
8. An amphibious vehicle as claimed in any one of claims 5 to 7, in which the actuation means is mounted to the actuator externally of the cylinder wall, with the pin being arranged to project through the cylinder wall into the path of the piston when in the first position.
9. An amphibious vehicle as claimed in claim 1, in which the stop means comprises a stop member mounted to the piston or to a linkage connected to the piston for movement between a first position in which it can contact a corresponding stop means associated with the cylinder to limit movement of the piston relative to the cylinder to the predetermined range, and a second position in which it is not arranged for contact with the corresponding stop means.
10. An amphibious vehicle as claimed in any previous claim, in which the actuator is a double acting hydraulic ram and is configured such that it also provides suspension and/or damping for the at least one wheel when the wheel is in the land support 1 5 position.
An amphibious vehicle as claimed in any previous claim in which the control means is arranged to automatically control deployment of the stop means.
12. An amphibious vehicle as claimed in any previous claim, in which the control means is arranged to withdraw the stop means from the deployed position to enable the at least one wheel to be moved between the land support and retracted positions.
13. An amphibious vehicle as claimed in claim 12, in which the stop means is normally deployed when the at least one wheel is in the land support position or the retracted position, the control means being arranged to withdraw the stop means from the deployed position only when the at least one wheel is to be moved between the land support and retracted positions. ] 14
14. An amphibious vehicle as claimed in claim I 1, or either of claims 12 and 13 when dependent on claim 11, in which the control means is arranged to automatically withdraw the stop member from its deployed position when the vehicle converts between a land use mode and a water borne mode.
15. An amphibious vehicle substantially as hereinbefore described, with reference to and as illustrated in Figures l to 3 of the accompanying drawings.