METHOD AND APPARATUS FOR OPERATING A MACHINE WORK TOOL

Technical Field

This disclosure is directed towards an apparatus for mounting to a work tool. The disclosure is further directed towards method of operating a machine comprising a work tool and an apparatus mounted to the work tool.

Background

Machines, including backhoe loaders, excavators, loaders and the like, commonly comprise a hydraulic control system for controlling one or more work tools, such as buckets, booms, backhoes, arms, grapples and the like. The hydraulic control system may comprise one or more actuators connected to each work tool and configured to move the work tool to perform work. A gas spring may be used in such machines in conjunction with the actuator to recover energy during movement of the work tool.

Before use, it is necessary to charge a gas spring with gas. This may be accomplished by supplying gas from a pressurised storage tank. However, the efficiency of such charging is limited in systems which rely on equalisation of pressure to move gas from the pressurised storage tank to the gas spring. In such a system, once the pressure equalises, gas remains in the storage tank at the equalised pressure, which is fixed by the volume of the system and the tank and the initial pressure in the tank.

It may be desirable to provide a system in which more of the gas, preferably all of the gas, can be transferred from the pressurised storage tank to the gas spring than is possible by equalisation of pressure.

Summary

The present disclosure therefore provides a method of operating a machine comprising a work tool and an apparatus mounted to the work tool, the apparatus comprising: a gas spring arrangement comprising a first gas chamber defined by a piston head moveably mounted inside a cylinder; and a gas supply apparatus comprising at least one gas storage tank having a fixed volume and containing a gas, wherein the at least one gas storage tank is fluidly connected by a gas supply conduit to the cylinder; wherein the method comprises a charging step for drawing gas from the at least one gas storage tank into the cylinder, the charging step comprising: moving the piston head in the cylinder to increase the volume of the first gas chamber to decrease a gas pressure in the at least one gas storage tank such that gas moves from the at least one gas storage tank into the cylinder; and preventing return of gas from the cylinder to the at least one gas storage tank during the charging step.

The present disclosure also provides an apparatus for mounting to a work tool, the apparatus comprising: a gas spring arrangement comprising a first gas chamber defined by a piston head moveably mounted inside a cylinder; and a gas supply apparatus comprising at least one gas storage tank having a fixed volume, wherein the at least one gas storage tank is fluidly connectable to the first gas chamber via a gas supply conduit; wherein: the piston head is configured to be moveable in the cylinder to increase the volume of the first gas chamber during a charging step to draw gas from the at least one gas storage tank into the cylinder; and a gas supply valve assembly is provided in the gas supply conduit, the gas supply valve assembly having a charging configuration in which the gas supply valve assembly prevents return of gas from the cylinder towards the at least one gas storage tank during the charging step.

The present disclosure also provides a machine comprising an apparatus according to the present disclosure, wherein the machine is optionally a vehicle.

Brief Description of the Drawings

By way of example only, aspects of apparatuses and methods of the present disclosure are now described with reference to, and as shown in, the accompanying drawings, in which: Figure 1 is a side elevation of a machine comprising an apparatus of the present disclosure;

Figure 2 is a schematic representation of an apparatus according to an aspect of the present disclosure in a “locked” configuration;

Figure 3 is a schematic representation of the apparatus of Figure 2 in a “charging” configuration;

Figure 4 is a schematic representation of the apparatus of Figure 2 in a “use” configuration;

Figure 5 is a schematic representation of the apparatus of Figure 2 in a “discharging” configuration;

Figure 6 is a schematic representation of a further apparatus according to an aspect of the present disclosure in a “locked” configuration;

Figure 7 is a schematic representation of the apparatus of Figure 6 in a “charging” configuration;

Figure 8 is a schematic representation of the apparatus of Figure 6 in a “use” configuration;

Figure 9 is a schematic representation of the apparatus of Figure 6 in a “discharging” configuration;

Figure 10 is a schematic representation of an arrangement of a further apparatus according to an aspect of the present disclosure;

Figure 11 is a schematic representation of a further apparatus according to an aspect of the present disclosure;

Figure 12 is a table illustrating combinations of valve configurations for the apparatus of Figure 11;

Figure 13 is a schematic representation of an apparatus according to the present disclosure in a combined actuator and gas spring arrangement;

Figure 14 is a side elevation of a machine comprising the apparatus of Figure 13;

Figure 15 is a schematic arrangement of a further apparatus according to an aspect of the present disclosure; and

Figure 16 is a is a schematic representation of an arrangement of a further apparatus according to another aspect of the present disclosure.

Detailed Description

In the following description, the equivalent reference numerals are used in different aspects to denote equivalent or similar features. The present disclosure is generally directed towards an apparatus for storing and recovering energy for operating a work tool of a machine and methods of operating gas spring arrangements. The apparatus comprises a gas spring arrangement that biases a piston to extend from a cylinder to provide a biasing force that can be used during operation of the work tool. The gas spring arrangement may recover energy using the gravitational down force of the weight of the work tool and release the energy during operation of the work tool to assist an actuator in moving the work tool.

Figure 1 illustrates a machine 10 of the present disclosure, which may comprise a main body 11 and a work tool 12 attached to the main body 11. The work tool 12 may comprise an arm arrangement 13 mounted to the main body 11 and an implement 14 attached to the arm arrangement 13 as illustrated. The work tool 12, particularly the arm arrangement 13, may be controlled by at least one actuator 15 to move the implement 14 and perform work. In the illustrated aspect the machine 10 comprises an excavator, although the machine 10 may be any other type comprising at least one actuator 15, such as a truck (e.g. a dump truck), backhoe loader, another type of loader such as a wheel loader or track loader, dozer, shovel, material handler or telehandler.

The machine 10 may further comprise an apparatus 120 of the present disclosure for storing energy for operating the work tool 12. The machine 10 may comprise a plurality of apparatuses 120.

The apparatus 120 is illustrated in further detail in Figures 2 to 5. Note, the key showing valve assembly configurations provided in Figure 2 applies to all of the figures and valve assemblies of the present disclosure. The apparatus 120 may comprise a gas spring arrangement 150 comprising first and second gas chambers 151, 152 formed by a piston 122 having a piston head 136 moveably mounted inside a cylinder 121. The piston 122 may be at least partially sealed and slidably mounted within the cylinder 121 and they are moveable relative to one another between an extended configuration and a retracted configuration. The cylinder 121 and piston 122 may have a generally round cross-section.

The cylinder 121 may comprise a cylinder wall 124 extending between first and second cylinder ends 125, 126. The first and second cylinder ends 125, 126 may be formed by first and second cylinder end caps 128, 129, which may seal the cylinder wall 124. The first cylinder end cap 128 may comprise a first mount 130 for mounting the cylinder 121 to the work tool 12 and/or main body 11.

The piston 122 may comprise a piston rod 135 attached to a piston head 136 mounted and sealed in the cylinder 121. The piston head 136 may comprise first and second head surfaces 137, 138 and the second head surface 138 may have a lower surface area than that of the first head surface 137. The first head surface 137 may oppose and be located towards the first cylinder end 125 and the second head surface 138 may oppose and be located towards the second cylinder end 126. A piston head seal 139 may be mounted to and extend around the piston head 136, particularly its side, for forming a seal between the piston head 136 and cylinder 121. The second cylinder end 126 and second cylinder end cap129 may comprise a rod passageway 140 in which the piston rod 135 is mounted and through which the piston rod 135 may slidably move. A piston rod seal 141 may extend around and be mounted to the rod passageway140 for forming a seal between the piston rod 135 and cylinder 121. Lubricating oil 147 may be located inside the cylinder 121 adjacent to the piston rod seal 141 for providing lubrication and sealing. The piston rod 135 may comprise an outer piston end 142 at the opposite end of the piston rod 135 to the piston head 136.

The gas spring arrangement 150 is configured to store and release energy to assist in the operation of the work tool 12. The first gas chamber 151 may extend between the first head surface 137, the first cylinder end 125 and the cylinder wall 124. The second gas chamber 152 may extend from the second head surface 138 towards the second cylinder end 126 and may, as illustrated, extend between the piston rod 135 and the cylinder wall 124. The first and second gas chambers 151, 152 may have variable volume based upon the movement of the piston 122 relative to the cylinder 121 and particularly based upon the position of the piston head 136 within the cylinder 121. Thus the first gas chamber 151 is configured to reduce in volume, and the second gas chamber 152 is configured to increase in volume, when the piston head 136 moves towards the first cylinder end 125 and vice- versa.

The machine 10 may comprise at least one actuator 15 mounted to the work tool 12 for operating the work tool 12 and at least one apparatus 120 mounted to the work tool 12 to store and release energy. An actuator fluid system 170 for operating the work tool 12 by actuation of the actuator 15 [ may be operable to apply force to the piston head (directly or via the work tool) 136 to extend and retract the piston 122 from the cylinder 121. The apparatus 120 may therefore be a separate component from the actuators 15 and may therefore provide a separate means of storing energy.

The gas spring arrangement 150 may further comprise a gas connection arrangement 153 for fluidly connecting the first gas chamber 151 to the second gas chamber 152. The gas connection arrangement 153 is configured to enable gas to be transmitted between the first and second gas chambers 151, 152 when the piston 122 moves relative to the cylinder 121 during use of the work tool. In operation the gas spring arrangement 150 may be charged by supplying gas to the first and second gas chambers 151,152 up to an initial usage pressure through the gas connection arrangement 153.

The gas spring arrangement 150 may further comprise a pressurised gas, such a nitrogen gas, located within the first and second gas chambers 151, 152 and gas connection arrangement 153.

The gas connection arrangement 153 may comprise at least one gas spring conduit 190. The at least one gas spring conduit 190 may extend from the first gas chamber 151 out of the cylinder 121 and to the second gas chamber 152. The at least one gas spring conduit 190 may extend through the cylinder wall 124 or may extend through the first and/or second cylinder ends 125, 126 as illustrated. The at least one gas spring conduit 190 may comprise at least one pipe, hose or the like. The gas connection arrangement 153 may comprise at least one gas spring valve 191 for controlling the flow of gas through the at least one gas spring conduit 190. The at least one gas spring valve 191 may be actuated to move it into various configurations as described below.

The present disclosure further provides a gas supply apparatus 193 fluidly connected to at least one gas chamber 151, 152. In the illustrated aspect the apparatus 120 of the present disclosure comprises the gas supply apparatus 193, which may be fluidly connected to the at least one gas spring conduit 190 of the gas connection arrangement 153 and may be connected between the gas spring valve 191 and the first gas chamber 151. However, the gas supply apparatus 193 may be applied to any gas spring arrangement 150 for a machine 10 having at least one gas chamber 151, 152. The gas supply apparatus 193 may comprise at least one gas supply conduit 194 to which at least one gas storage tank 195 is fluidly connected, such as by at least one gas storage adapter 197. The at least one gas storage adapter 197 may comprise valves or the like, a relief valve (such as a burst disc arrangement) and an adapter connector, such as screw threads, to which the at least one gas storage tank 195 may be releasably attached. The at least one gas storage tank 195 may have a fixed volume. The at least one gas storage tank 195 may be a gas cylinder and/or pressure vessel configured to store gas at a relatively high pressure (i.e. at least at the pre-charge and retracted pressures) and may comprise a tank adapter, such as screw threads, for releasably attaching to an adapter connector.

The at least one gas storage tank 195 may be mounted outside of and/or separated from the cylinder 121, such as by being mounted to outside of the cylinder 121, machine 10 and/or work tool 12. Preferably the at least one gas storage tank 195 is a gas bottle or bottled gas, which are commercially and commonly available. The at least one gas storage tank 195 may comprise a transportable gas storage tank that complies with a regional standard, such as ISO 24431 :2016(en).

The gas supply apparatus 193 may be fluidly connected to the cylinder 121 for charging and discharging the gas spring arrangement 150. The at least one gas storage tank 195 may be removable such that it can be disconnected from the machine 10 when charging or discharging of the gas spring arrangement 150 is not taking place.

The gas supply conduit 194 may be fluidly coupled to the at least one gas spring conduit 190 at a junction103. The gas supply apparatus 193 may therefore be fluidly connected to the first and second gas chamber 151, 152 by the at least one gas spring conduit 190. A gas supply valve 101 for selectively controlling the flow of gas from the at least one gas storage tank 195 may be provided on the gas supply conduit 194.

A main valve for may be provided for isolating the gas spring arrangement 150 from the gas supply conduit 194. The main valve 102 may be provided on the gas supply conduit 194 between the gas supply valve 101 and the gas spring conduit 190. The gas spring valve 191, the gas supply valve 101 and the main valve 102 may be actuated into particular configurations such that the cylinder 121 may act as a pump to draw gas from the at least one gas storage tank 195 to charge the gas spring arrangement 150 to an initial operating pressure.

The gas spring valve 191 may be moveable between: - a charging configuration in which any flow through the gas spring valve is in a direction from the first gas chamber towards the second gas chamber; and

- a use configuration in which any flow through the gas spring valve is allowed both from first gas chamber towards the second gas chamber and from the second gas chamber towards the first gas chamber; and a discharging configuration in which any flow through the gas spring valve is in a direction away from the second gas chamber.

The gas supply valve 101 may be moveable between:

- a charging configuration wherein any flow through the gas supply valve 101 is in a direction from the at least one gas storage tank 195 to the cylinder 121;

- a use configuration wherein the gas supply valve 101 prevents flow therethrough; and a discharging configuration in which any flow through the gas supply valve 101 is in a direction from the cylinder 121 to the at least one gas storage tank 195.

The main valve 102 may be moveable between:

- a charging and discharging configuration in which the main valve 102 is configured to allow flow in any direction therethrough; and

- a use configuration in which the main valve 102 is closed to prevent flow therethrough.

Alternatively, in the use configuration the main valve 102 may configured to allow flow in any direction therethrough.

Any of the valves may be moveable to an “off” configuration in which no flow through the valve is permitted. Optionally, all of the valves except the gas spring valve 191 may be moveable to an “off’ configuration.

The present disclosure therefore also provides a method of charging and discharging the gas spring arrangement 150, such as during maintenance, installation or uninstallation, using the at least one gas storage tanks 195 of the storage and/or gas supply apparatus 193.

The method of charging the gas spring arrangement 150 comprises moving the piston head 136 in the cylinder 121 to increase the volume of the first gas chamber 151 to decrease the pressure of gas in the at least one gas storage tank 195, while preventing return of gas from the cylinder 121 to the at least one gas storage tank195 during the charging step. Preventing return of gas from the cylinder 121 to the at least one gas storage tank 195 during the charging step may comprise actuating the gas supply valve 101 into a charging configuration in which any flow through the gas supply valve 101 is in a direction from the at least one gas storage tank 195 towards the cylinder 121. The method may comprise actuating the gas spring valve 191 into a configuration in which any flow through the gas spring valve 191 is in a direction towards the second gas chamber 152 during the charging step. Valve configurations for charging the cylinder 121 may be as shown in Figure 3, with gas flow illustrated by directional arrows in the conduits.

For example, a method of charging a gas spring arrangement 150 to an initial operating pressure may comprise the following steps:

- Opening the main valve 102 to allow flow in both directions through the gas supply conduit 194 (i.e. to and from the cylinder 121);

- Actuating the gas supply valve 101 into a charging configuration in which any flow through the gas supply valve is in a direction from the at least one gas storage tank towards the cylinder;

- Actuating the gas spring valve 191 into a configuration in which any flow through the gas spring valve is in a direction towards the second gas chamber 152; and

- Moving the piston head 136 in a reciprocal motion such that gas is drawn from the gas supply apparatus 193 to the cylinder 121 until the pressure within the cylinder reaches the required initial operating pressure.

Optionally, the cylinder 121 may be charged to a test pressure which is different to the operating pressure, for example for testing purposes.

Between the charging and discharging steps, the gas spring arrangement 150 may be arranged in a use configuration, in which the gas supply conduit 194 is blocked (for example, by the gas supply valve 101). Valve configurations for the use configuration may be as shown in Figure 4, with gas flow illustrated by directional arrows in the conduits. The gas spring valve 191 may be in a configuration in which flow of gas through the gas spring conduit 190 is allowed both from the first gas chamber 151 to the second gas chamber 152 and from the second gas chamber 152 to the first gas chamber 151 (as indicated by the arrows in Figure 4). Any flow of gas in the gas spring arrangement 150 in the use configuration may therefore be between the first and second gas chambers 151,152 on movement of the piston 122, and no gas enters or leaves from the gas spring arrangement 150 (except by normal operational losses).

The gas storage tanks 195 may be configured to be removable during normal use of the gas spring arrangement 150 (i.e. when the work tool 12 is in use, rather than during charging and discharging of the gas spring arrangement 150).

An example method of using the gas spring arrangement 150 may comprise the following steps:

- Actuating the gas spring valve 191 into a configuration in which flow through the gas spring valve 191 is allowed both from first gas chamber 151 towards the second gas chamber 152 and from the second gas chamber 152 towards the first gas chamber 151;

- Actuating the gas supply valve 101 into a configuration in which flow is not permitted therethrough; and

- Using the gas spring arrangement 150 to recover energy from operation of the work tool 12.

The present disclosure may further comprise a method of discharging the gas spring arrangement 150. This method may comprise actuating the gas supply valve 101 into a configuration in which any flow through the gas supply valve 101 is in a direction from the cylinder towards the least one gas storage tank 195, and actuating the gas spring valve 191 into a configuration in which any flow through the gas spring valve 191 is in a direction away from the second gas chamber 152. Valve configurations for discharging the cylinder 121 may be as shown in Figure 5, with gas flow illustrated by directional arrows in the conduits.

For example, the discharging method may comprise the following steps:

- Opening the main valve 102 to allow flow in both directions through the gas supply conduit 194 (i.e. to and from the cylinder 121);

- Actuating the gas supply valve 101 into a configuration in which any flow through the gas supply valve 101 is in a direction from the cylinder 121 towards the least one gas storage tank 195; - Actuating the gas spring valve 191 into a configuration in which any flow through the gas spring valve 191 is in a direction away from the second gas chamber 152; and

- Moving the piston head 136 in a reciprocal motion such that gas is pumped to the gas storage tank 195 from the cylinder 121 until the cylinder 121 is fully discharged.

The piston may be moved by the actuator fluid system 170 during discharge. The system pressure after discharge may be between 100kPa and 1000kPa (atmospheric pressure being 100kPa).

Once discharged, the apparatus may be placed in a locked configuration, as shown in Figure 2, in which the gas supply valve 101 and main valve 102 (if present) are in configurations preventing flow therethrough, and the gas spring valve 191 is configured to allow flow therethrough both from first gas chamber 151 towards the second gas chamber 152 and from the second gas chamber 152 towards the first gas chamber 151. The valves may be moved to the required configurations in the following order: gas spring valve, main valve, supply valve. The apparatus may be kept in the locked configuration whenever it is not being operated.

The gas in the gas spring arrangement 150 may also be ventilated to the environment to remove any remaining pressurised gas such that the gas in the gas spring arrangement 150 reaches the ambient pressure. The apparatus 120 may comprise additional venting and/or relief valves (for example a ball valve) to assist with such removal. Relief valves may be actuated automatically to prevent over-pressurisation of the system.

Figures 6 to 9 illustrate an apparatus according to a further aspect of the present disclosure. The apparatus is as in the previous aspect, but comprises one or more top-off tanks 200 for adding additional gas into the system during use or maintenance, for example to compensate for leakage. The top-off tank(s) 200 may be removable. For example, the top-off tanks 200 may be connected to the rest of the apparatus only during maintenance.

As shown in Figures 6 to 9, the one or more top-off tanks 200 may be fluidly connected to the gas supply conduit 194 at a junction 202 arranged between the main valve 102 and the gas supply valve 101. When the apparatus is in the locked configuration (as in Figure 6), during charging of the cylinder 121 (as in Figure 7) and discharging of the cylinder (as in Figure 9) a top-off valve 201 arranged between the one or more top-off tanks 200 and the gas supply conduit 194 may be actuated into a configuration in which flow is prevented therethrough. When the apparatus is in the use configuration (as in Figure 8), the top-off valve 201 may be actuated into a configuration in which any flow through the top-of valve 201 is in a direction from the one or more top-off tanks 200 into the gas supply conduit 194. As an alternative to closing the top-off valve 201 in the use configuration, in the use configuration the top-off valve 201 may be actuated into a configuration in which any flow through the top-of valve 201 is in a direction from the one or more top-off tanks 200 into the gas supply conduit 194.

Other features of the apparatus, in particular the gas supply valve 101, main valve 102 and gas spring valve 191 and their configurations may be as described for the previous aspects of the disclosures.

The top-off valve 201 may be provided with a pressure regulator 203 to enable gas to flow from the at least one top off tank 200 into the gas supply conduit 194 when the pressure in the cylinder 121 when extended reduces below the required pressure. As a result, the pressure of the gas spring arrangement 150 may be maintained at the required pressure in use. The top-off tank 200 and the top-off valve 201 may be configured to provide automatic top off only when the cylinder 121 is fully extended.

Figure 10 shows an exemplar schematic arrangement of an apparatus according to the present disclosure. The apparatus comprises a single top-off tank 200 and four gas storage tanks 195. Top-off valve 201 may be provided in the form of a valve assembly comprising an on-off valve and a check valve arranged in series. The valves 101, 102 and 191 and 201 may be controlled according to the configurations described in Figures 6 to 9 and above. A control system may be provided for automatic for control of the valves and valve assemblies A ball valve 207 (or other suitable valve) may be provided for venting the system or for use in testing.

Figure 11 illustrates an apparatus according to a further aspect of the present disclosure. The apparatus is as in the previous aspect, but comprises both one or more top off tanks and one or more expansion tanks 204. The one or more expansion tanks 204 may be configured to withstand repeated pressurisation and depressurisation cycles. The one or more expansion tanks 204 may be fluidly connected to the gas spring arrangement 150 to provide additional volume during use of the gas spring arrangement 150 in order to vary the compression ratio which may be achieved in the gas spring arrangement 150, preferably to lower the compression ratio. This may assist in reducing adiabatic losses.

The one or more expansion tanks 204 may be fluidly connected to the gas spring arrangement 150 using an expansion tank valve 205, which may be connected to the gas supply conduit 194. In this aspect, during discharge, the gas may be discharged to the either the one or more gas storage tanks 195 or to the one or more expansion tanks 204. Similarly, the cylinder 121 may be charged with gas from either the one or more gas storage tanks 195 or from the one or more expansion tanks 204. Charging from the one or more gas storage tanks 195 may be as described for other aspects of the present disclosure. Charging from the one or more expansion tanks 204 may be achieved by equalisation of pressure, without movement of the piston head 136. The valve configurations for the various modes of operation may be illustrated in Figure 12.

Other features of the apparatus, in particular the gas supply valve 101, main valve 102 and gas spring valve 191 and their configurations may be as described for the aspects of the disclosure above.

The top-off tank 200 and associated valves may optionally be omitted, such that the apparatus comprises one or more expansion tanks 204 in the absence of any top-off tanks 200.

In the preceding aspects, the apparatus and methods are described with reference to a gas spring arrangement which is separate to the work tool 12 and actuator 15. In any aspect of the present disclosure, the gas spring arrangement may alternatively be combined with the actuator 15, for example as shown in Figure 13.

Figure 13 illustrates an apparatus 220 according to the present disclosure in which the gas spring arrangement 250 is a part of a combined actuator and gas spring arrangement 215. The apparatus 220 may comprise a gas spring arrangement 250 that biases a piston to extend from a cylinder to provide a biasing force that can be used during operation of the work tool. The gas spring arrangement 250 may recover energy using the gravitational down force of the weight of the work tool 12 and release the energy during operation of the work tool 12 to assist an actuator 15 in moving the work tool 12. The apparatus 220 may also comprise an actuator fluid system such that the apparatus 220 is an integrated gas spring 250 and actuator 215. The gas spring arrangement 250 including the gas spring piston 236 and gas spring piston rod 235 may be formed in the cylinder 221 whilst the actuator fluid system including the hydraulic cylinder piston 271 and hydraulic cylinder rod 272 may be arranged in the piston. The hydraulic fluid for the actuator is shown as 273. As a result, the gas spring arrangement 250 may generally be formed around the actuator fluid system. In all other features the apparatus may be as described for the other aspects described herein. The valve configurations for the various modes of operation may be as illustrated in Figure 12.

A machine 10 comprising an apparatus 220 as illustrated in Figure 13 is shown in Figure 14.

Whilst preferred aspects of the present disclosure have been described, these are by way of example only and non-limiting. It will be appreciated by those skilled in the art that many alternatives are possible within the ambit of the disclosure. Features described as part of one aspect may be combined with features of one or more other aspects unless the context clearly requires otherwise. The skilled person will understand that features of the present disclosure are interchangeable between aspects described in the context of the apparatus and aspects described in the context of the method. In the methods of the present disclosure, the order of steps in the method may be as described. Skilled person will appreciate order of steps may be changed where technically feasible, unless the context clearly requires otherwise.

Any apparatus according to the present disclosure comprises a number of valves as described above, for example the gas supply valve and the gas spring valve. Each of these valves may be moveable between a number of different configurations (i.e. components of the valve may be moved between different set positions), each configuration allowing or permitting flow through the valve in a specified direction. In the present disclosure, when a valve is described as being in a configuration in which flow through the valve is in a particular direction, this means that the valve in that configuration only permits flow through the valve only in the specified direction, flow in the any other direction being prevented by the valve. Where a valve as described as having or being actuated into a particular configuration “during” a particular step of the method, the valve may remain in that configuration throughout that method step. Figure 15 illustrates a further an exemplar schematic arrangement of an apparatus according to the present disclosure, in which top-off valve 201 is in the form of a valve assembly comprising a check valve and an on-off valve and gas spring valve 191 is also in the form of a valve assembly. The apparatus further comprises a control system 206.

Other features and the valve configurations for the various modes of operation may be as illustrates in Figures 6 to 9.

In any aspect, the actuation of the gas supply valve and/or the gas spring valve into the required configurations may controlled by a control system. In any aspect, the control system may be configured to use energy from gas contained in the apparatus to actuate the valve or valves, for example as shown in Figure 16. One or more of the valves of the present disclosure may be ball valves, which must be rotated to change the configuration of the valve. The torque required to rotate the ball in a ball valve may depend on pressure that the ball is subjected to by the flow of gas, which may result in high actuation forces Actuation of the ball valve may be achieved using a rack and pinion actuated by a hydraulic cylinder (i.e. using and external energy source). Alternatively, a control system for one or more valves may comprise a resolver valve or at least two check valves configured to act as a resolver, using the higher of two pressures from the system to actuate the valve.

Figure 16 illustrates an example control system 206 for actuation of the valves. The system is otherwise as shown in Figure 11, and the valve configurations for the various modes or configurations of the system are as shown in Figure 12. A control system of this type may be used in any apparatus of the present disclosure, for example in the system shown in Figure 15.

In the illustrated and described aspects, sets of valve configurations are shown for various modes of operation of the system. The skilled person will appreciate that the various modes of operation illustrated are exemplary, and an apparatus according to the present disclosure may not be configurable into all of the exemplary use modes illustrated.

In any aspect, the charging step may comprise flow of gas resulting from equalisation of pressure when the or each gas storage tank is connected to the gas spring arrangement and the valves are configured to allow flow therethrough, further flow of gas may then occur due to movement of the piston in the cylinder, for example as a result of movement of the work tool. In any aspect, the discharging step may comprise a flow of gas resulting from movement of the piston in the cylinder. In any aspect, during the charging and/or discharging step the piston may move in a reciprocating movement. This movement may comprise one or more complete cycles of movement (one cycle being complete once the piston head has reached each extent of the its range of motion and returned to its starting position). The movement may comprise at least two cycles of movement.

In any aspect, the apparatus of the present disclosure may comprise a control system configured to operate the valves and piston of the apparatus to carry out at least one, preferably of the methods of the present disclosure.

References to “flow” in this application refer to a flow of a gas contained in the apparatus unless otherwise specified or dictated by context.

In any aspect, the main valve 102 may be omitted. If present, the main valve 102 may be in a closed configuration when the gas spring is in use to provide isolation of the gas spring from the gas supply apparatus. In any aspect, the apparatus may comprise any number of top-off tanks 200.

In use, the apparatus of the present disclosure may be mounted to a machine 10 comprising a work tool 12 as in Figure 1. The machine 10 may, for example, be a vehicle or other type of machine. The movement of the piston head may be controlled during the charging and/or discharging steps by actuation of a work tool attached to the machine. The work tool may be actuated by a hydraulic or other actuator, the gas supply conduit 194 and the gas spring conduit 190 therefore being independent of each other.

As described in the aspects above, the gas supply conduit 194 may be fluidly coupled to the at least one gas spring conduit 190. Alternatively, the gas supply conduit 194 may be fluidly coupled directly and mounted to the first or second gas chamber 151, 152.

In the illustrated aspects, the first gas chamber is the chamber defined by the first head surface 137 and the second gas chamber is the chamber defined by the second head surface 138. Alternatively, the second gas chamber may be the chamber defined by the first head surface 137 and the first gas chamber may the chamber defined by the second head surface 138. In any aspect, the one or more gas storage tanks may be provided with gas tank valves. The method of the present disclosure may comprise the step of opening the gas tank valves. In the “locked” configuration or during use of the work tool, when the gas supply apparatus may be removed from the rest of the apparatus, the method may comprise the step of closing the gas tank valves.

In any aspect, the top-off valve may have no configuration in which flow is allowed in a direction from the cylinder into the top-off tank or tanks.

In any aspect, one or more of the valves of the present disclosure may be provided with locking devices.

Where aspects of this disclosure refer to a valve which is moveable into a configuration allowing a particular flow pattern, it is to be understood that this valve may comprise a valve assembly comprising one or more valves, for example arranged in series, moveable into a configuration allowing the required flow pattern. For example, the gas spring valve 191 may be a gas spring valve assembly. Similarly, where aspects of this disclosure refer to a valve assembly allowing a particular flow pattern, it is to be understood that this valve assembly may comprise a single valve moveable into a configuration allowing the required flow pattern.

Industrial Applicability

The method and apparatus of the present disclosure may therefore provide a more efficient way of charging a gas spring system. The gas may be drawn from the pressurised storage tank by movement of the piston head, for example by a hydraulic or other motor. Gas may therefore be provided from a gas supply apparatus at any pressure. This may reduce number of gas supply apparatus required to fully charge the system as more of the gas can be retrieved from each gas supply apparatus into the gas spring.

The method and apparatus of the present disclosure may allow for reciprocal movement of the piston to continue drawing gas from the gas supply apparatus during aspiration without the need to reconfigure the valves between strokes of the piston during the aspiration step and during discharging.

The use of a control system using system pressure to actuate valves may ensure there is always sufficient pressure to actuate the valves, with no external power source required. The method and apparatus of the present disclosure may also provide a system in which the work tool or actuator may be arranged in any position at the start of the charging or discharging step. It may therefore be unnecessary to return the work tool or actuator to a start position (typically the top or bottom of its range of movement) before charging or discharging the gas spring.