TITLE
"APPARATUS AND METHOD FOR ACTUATING A HYDRAULIC CYLINDER "
[0001] The present invention relates to an apparatus and method for actuating a hydraulic cylinder.
[0002] More particularly the present invention relates to an apparatus and method for actuating a hydraulic cylinder for use in remotely servicing hydraulic cylinders of industrial machinery.
[0003] Large hydraulic machinery is often used in a number of primary industries, and may be used on site, distant to facilities suitable for maintenance and repair.
[0004] Should a hydraulic cylinder unit fail or require maintenance, it is known to perform repairs on site, and to replace the hydraulic cylinder. The task of servicing or replacing a hydraulic cylinder carries a number of risks, which are typically greater risks where larger machines are involved due to the increased masses and forces.
[0005] A cylinder on a machine may be under significant load, due to the connected hardware at either end, and the cylinder may need to be braced to support this load sufficiently to remove the mountings at each end. Furthermore, the cylinder itself may be very heavy, and require bracing so that when the mounting features are undone, the cylinder does not fall or swing, becoming potentially dangerous.
[0006] To assist with the operation, the controls of the machine may be used to try and move the cylinder, or associated hardware, to an orientation and position which provides a safer environment for removal and replacement. To move the cylinder, and to effectively adjust the load, requires small movements and changes in pressure within the cylinder. Machines are designed to be used for their intended function, and generally do not carry the capability for such small and gradual changes.
[0007] Furthermore, known machines are typically controlled from a cabin, or similar position suited for the use of the machine, where this position is not necessarily suitable for the repair and replacement of the cylinder. Consequently, a minimum of two operators are normally required to carry out service or replacement of a cylinder. The requirement for multiple operators carries inherent risk, where communication breakdown or an error when working the controls presents a significant risk of harm.
[0008] In addition, the use of the controls of the machine to assist with the repair and replacement operation requires that the machine itself be live, which also carries risks to any operators nearby.
[0009] The present invention attempts to overcome at least in part the aforementioned disadvantages of previous methods of servicing and replacing hydraulic cylinders.
SUMMARY OF THE INVENTION
[0010] In accordance with one aspect of the present invention there is provided an apparatus for remotely actuating a hydraulic cylinder of a hydraulic machine, the apparatus comprising; feed and return hydraulic hoses, each being connected to, and in fluid communication with, hydraulic fluid supply means, extend and retract hydraulic hoses, each being removeably connected to, and in fluid communication with, respective extend and retract ports of the hydraulic cylinder of the machine, a hydraulic pump, a directional valve configured to direct flow of hydraulic fluid from the feed hose to either one of the return hose, the extend hose or the retract hose, and
a control means for operating the hydraulic pump and directional valve, whereby the apparatus enables the hydraulic cylinder of the machine to be extended or retracted using the control means.
[0011] The directional valve may comprise means to direct excess hydraulic fluid to the return hose.
[0012] The hydraulic pump may be an electric hydraulic pump.
[0013] The hydraulic pump may be powered by an electric motor.
[0014] The pump and directional valve may be housed in a case.
[0015] The apparatus may further comprise a filter upstrea of the hydraulic pump, wherein the filter is configured to remove particulates and contaminants from the hydraulic fluid before entering the pump.
[0016] The apparatus may further comprise at least one pressure gauge, the or each pressure gauge being configured to read the pressure of the hydraulic fluid at a chosen position in the system.
[0017] The apparatus may further comprise a bleed valve, configured to release excess pressure from the hydraulic system when opened.
[0018] The apparatus may further comprise a relief valve, configured to relieve excess pressure above a certain level.
[0019] The hydraulic pump may be configured to deliver hydraulic fluid at a flow rate of between 10 litres per minute and 50 litres per minute.
[0020] The control means may comprise a pendant, remotely connected to the apparatus by a cable, and be configured to control the pump and directional valve electronically.
[0021] The control means may further comprise an emergency stop feature, configured to cut power to the apparatus when actuated.
[0022] The hydraulic fluid supply means may be a hydraulic reservoir of the item of hydraulic machinery, the hydraulic reservoir having ports to connect the feed and return hoses.
[0023] The hydraulic hoses may comprise adaptors for connection to the ports of the machine, wherein the adaptors are interchangeable to allow appropriate adaptors to be fitted for a particular type of port.
[0024] In accordance with one further aspect of the present invention there is provided a method for using an apparatus to remotely actuate a hydraulic cylinder of a machine, the apparatus comprising;
Feed and return hydraulic hoses, each being connected to, and in fluid communication with, hydraulic fluid supply means,
Extend and retract hydraulic hoses, each being removeably connected to, and in fluid communication with, respective extend and retract ports of the hydraulic cylinder of the machine,
A hydraulic pump,
A directional valve configured to direct flow of hydraulic fluid from the feed hose to either one of the return hose, the extend hose or the retract hose, and
A control means for operating the hydraulic pump and directional valve, whereby the apparatus enables the hydraulic cylinder of the machine to be extended or retracted using the control means, and the method comprising the steps of;
a) Identifying a hydraulic cylinder requiring sendee on a machine; b) Disconnecting hydraulic hoses of the machine from extend and retract ports of the hydraulic cylinder; c) Replacing the hydraulic cylinder if required; d) Connecting the extend hose of the apparatus to the extend port of the hydraulic cylinder, e) Connecting the retract hose of the apparatus to the retract port of the hydraulic cylinder, f) Connecting the feed hose of the apparatus to a port of the hydraulic fluid supply means, g) Connecting the return hose of the apparatus to another port of the hydraulic fluid supply means, h) Using the control means to engage the hydraulic pump, i) Using the control means to operate the directional valve to perform extend and retract movements of the cylinder as required, j) Disconnecting the extend and retract hoses of the apparatus from the respective extend and retract ports of the hydraulic cylinder k) Re-connecting the hydraulic hoses of the machine to the extend and retract ports of the hydraulic cylinder.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
[0026] Figure 1 is a schematic diagram showing the key elements of the apparatus and the interaction with a hydraulic cylinder.
[0027] Figure 2 is an illustration showing the apparatus connected to a hydraulic cylinder on a machine.
DETAILED DESCRIPTION
[0028] Referring to the Figures, there is shown an apparatus for actuating a hydraulic cylinder in accordance with an embodiment of the present invention.
[0029] The apparatus 10 comprises feed and return hydraulic hoses, extend and retract hoses, a hydraulic pump 20, a directional valve 40 and control means 50.
[0030] The feed and return hydraulic hoses are each removeabley connected to, and in fluid communication with, hydraulic fluid supply means. The extend and retract hydraulic hoses are each removeably connected to, and in fluid communication with, respective extend and retract ports of the hydraulic cylinder of the machine.
[0031 ] The directional valve 40 is configured to direct flow of hydraulic fluid from the feed hose to either one of the return hose, the extend hose or the retract hose, and the control means 50 is for operating the hydraulic pump 20 and directional valve 40.
[0032] The apparatus 10 enables the hydraulic cylinder of the machine to be extended or retracted using the control means 50.
[0033 ] As shown in Figure 1 , the preferred embodiment of an apparatus 10 according to the present invention comprises a hydraulic pump 20 powered by an electric motor 30, a directional solenoid valve 40 and a pendant control 50.
[0034] The hydraulic pump 20, electric motor 30 and directional solenoid valve 40 are preferably housed in a case 60 for ease of transportation, with the pendant control 50 being remote to the case, thus allowing operation of the pendant control 50 at a distance from the apparatus 10.
[0035] The electric motor 30 is supplied with power from an external source in the preferred embodiment, and may comprise a connection to the case 60, which further comprises a suitable power connection 62 on the exterior of the case 60.
[0036] The hydraulic pump 20 is driven by the electric motor 30, and comprises and input port 22 and output port 24 for transmission of hydraulic fluid. The input port 22 may be connected to the case 60, which comprises a corresponding feed port 64 on the exterior of the case 60.
[0037] Hydraulic fluid is supplied to the pump 20 by connecting a supply to the feed port 64 on the exterior of the case 60.
[0038] The directional solenoid valve 40 preferably comprises four ports, being an input port 42 and output port 44 for feed and return of hydraulic fluid, and a further two ports, being described as an extend port 46 and a retract port 48, for directing the flow of hydraulic fluid.
[0039] Where hydraulic fluid is supplied at pressure from the hydraulic pump 20 to the input port 42 of the directional solenoid valve 40, the valve 40 is able to direct the flow of the hydraulic fluid toward either the extend port 46 or retract port 48 using the solenoid to alternate the direction.
[0040] The extend port 46 of the directional solenoid valve 40 is connected to the case 60, which comprises a corresponding extend port 68, suitable for connecting a hose.
Similarly, the retract port 48 of the directional solenoid valve 40 is connected to the case 60, which comprises a corresponding extend port 69, suitable for connecting a hose.
[0041 ] The directional solenoid valve 40 may further direct flow of hydraulic fluid toward the output port 44 when in a nominal position, thus cycling hydraulic fluid through the system where the pump 20 is active, but not directing the hydraulic fluid toward either the extend port 46 or retract port 48.
[0042] Where the directional solenoid valve 40 is directed toward a first position the flow of hydraulic fluid is directed toward the extend port 46, thus extending the hydraulic cylinder. The fluid returned from the hydraulic cylinder is received at the retract port 48 of the directional solenoid valve 40, and directed toward the output port 44, and subsequently to a return port 66 on the case 60.
[0043] Where the directional solenoid valve 40 is directed toward second position the flow of hydraulic fluid is directed toward the retract port 48, thus retracting the hydraulic cylinder. The fluid returned from the hydraulic cylinder is received at the extend port 46 of the directional solenoid valve 40, and directed toward the output port 44, and subsequently to the return port 66 on the case 60.
[0044] Therefore the apparatus 10 is able to perform extend and retract operations of a connected hydraulic cylinder using the directional solenoid valve 40, where excess or returned hydraulic fluid is directed to the return port 66.
[0045] While the preferred embodiment of the present invention uses a three directional solenoid valve 40 to direct the flow of hydraulic fluid, it is recognised that other means mean be used while not detracting from the invention.
[0046] Preferably the flow rate of the pump 20 is selected to feed hydraulic fluid at a rate suitable for gradual adjustment of a cylinder, this rate may be 20 to 30 litres / min.
[0047] The flowrate of hydraulic fluid in the system of an operational machine is typically much greater, due to the requirement to perform movements at an appropriate
pace for the intended task, consequently the gradual adjustment of the cylinder movement afforded by the use of the apparatus 10 according to the present invention would not be possible using the controls of the machine to adjust the cylinder.
[0048] The apparatus 10 is connected to a source of hydraulic fluid, preferably the source is a hydraulic fluid reservoir of the machine being serviced. In this case a feed hose connects the feed port 64 of the apparatus 10 to the reservoir, and a return hose connects the return port 66 of the apparatus 10 to the reservoir.
[0049] Preferably the hoses are connected either side of a filter of the reservoir to improve filtering of the hydraulic fluid in the system.
[0050] Preferably the apparatus 10 further comprises a filter fitted between the feed port 64 of the apparatus 10 and the hydraulic pump 20, to ensure hydraulic fluid is filtered before entering the system and reduce potential for damage.
[0051 ] Preferably the apparatus 10 draws power from a separate source, for example a generator. Thus keeping the size and weight of the apparatus 10 to a minimum, allowing for easier transportation.
[0052] The use of external power and a separate hydraulic fluid reservoir allows the apparatus 10 to be kept relatively small and light, and therefore becoming transportable, useful where the machine requiring servicing has broken down in the field.
[0053] Portability also allows an operator to transport the apparatus 10 to the site, but also to situate the apparatus 10 at a location in the vicinity of the machine, with the location being chosen for the operator to be safe from harm while performing the service or replacement of cylinders.
[0054] An alternative embodiment of the apparatus 10 in accordance with the present invention further comprises a hydraulic fluid reservoir, thereby reducing the reliance on the hydraulic system of the machine subject to repair, and reducing the number of connections required during the operation. The addition of the hydraulic fluid reservoir
increases the size and weight of the apparatus 10, thus potentially affecting transportability.
[0055] An alternative embodiment of the apparatus 10 in accordance with the present invention further comprises means of power supply, thus further preventing the need for a separate generator or other power supply means, but further increasing the size and weight of the apparatus, and potentially affecting transportability.
[0056] While the preferred embodiment of the apparatus 10 of the present invention is intended to be portable, it is recognised that other embodiments exist which may be of such a size and weight that they are more cumbersome. In such instances further options exist for transportation, for example the apparatus 10 may be transported on the back of a vehicle, or even permanently mounted to a vehicle, and driven to the required location.
[0057] In use, the operator performs a number of steps which would be required if performing the procedure without the use of the apparatus 10, but which are included here for clarity and to provide a complete description of the procedure.
[0058] Firstly, the operator identifies the cylinder to be serviced, and positions the apparatus 10 at a location suitable for connecting the relevant hydraulic hoses, but also to allow the operator to position himself at a location where he may be safe from harm if the machine were to move unexpectedly for example.
[0059] A number of standard site safety checks may be required, for example isolating the machine to ensure power is not running, fitting wheel chocks if required, and tagging the machine to indicate its current state.
[0060] The operator ensures that any parts of the machine which may move when hydraulic feed to the cylinder is disconnected are braced. For example a digger may have a heavy bucket or hoe on the end of the members used in operation. The weight of the bucket maybe such that the cylinder requiring service is subjected to significant loading,
so that removing this cylinder is both difficult and dangerous unless the bucket is supported by bracing.
[0061] The loading of associated componentry such as the bucket affects both the pressure within a hydraulic cylinder, and the forces exerted on the end connections.
[0062] The operator identifies the hydraulic tank on the machine or other hydraulic fluid supply means, and connects the suction hose from the feed port 64 of the apparatus 10 to a port on the hydraulic tank of the machine. The port on the machine may comprise a cap, or blank, which must be removed before connecting the hose.
[0063] Ports of different machines may require the use of adaptors, as not all machines use the same standard of ports. This is true both for ports on the hydraulic fluid reservoir and the extend and retract ports on the hydraulic cylinder.
[0064] The operator then connects the return hose from return port 66 of the apparatus 10 to another port on the hydraulic tank of the machine or other hydraulic fluid supply means. This port may be made upstream of a filter if possible, to improve the filtering of hydraulic fluid. Again, the port on the machine may comprise a cap, or blank, which must be removed before connecting the hose.
[0065] The operator then ensures hydraulic pressure is released from the cylinder to be serviced before disconnecting any hoses, this may be done by opening a bleed valve to allow excess pressure to escape.
[0066] Hydraulic accumulators may also be used on some machines, which may also be discharged to ensure excess pressure has been removed from the system.
[0067] Some movement may occur during bleeding of the system, due to load exerted by the connected hardware. Any movement should settle as the bracings take the load and allow the pressure to equalise.
[0068] Once pressure has equalised, disconnect the hoses from extend and retract ports of the cylinder to be serviced.
[0069] If the cylinder requires replacement, the following steps should be carried out, alternatively, if the cylinder requires servicing or adjustment without replacement, the following steps are not required, and the procedure can commence again from paragraph [0074].
[0070] Ensure the cylinder is braced, so that the weight is supported without the end connections being subject to significant load.
[0071 ] Undo the connections at each end of the cylinder. Connections will typically be in the form of a sleeved bearing to enable rotational movement, these can be disconnected by undoing and removing the pin, however if the cylinder is still subject to significant load, removing the pin may be difficult or impossible. In this case steps [0074] thru [0085] may be performed to assist with removing undue loads before returning to step [0070].
[0072] Remove the cylinder from the machine, this may require the use of lifting equipment in the case of larger cylinders, and appropriate care should be taken to reduce risk of harm.
[0073] Position the replacement cylinder, again using lifting equipment if required, and connect the ends.
[0074] Connect a hydraulic hose from the extend port 68 of the apparatus 10 to the extend port of the cylinder, using adaptors if required.
[0075] Connect a hydraulic hose from the retract port 69 of the apparatus 10 to the retract port of the cylinder, using adaptors if required.
[0076] Connect pressure gauges as required. Pressure gauges assist with determining pressure within the cylinder, and therefore the pressure required to achieve movement of the cylinder.
[0077] Ensure the bleed valve is closed to allow the cylinder to be pressurised again.
[0078] Connect the pendant controller 50, the use of a pendant controller 50 allows an operator to stand at a range of locations within the reach of the cable, this is useful for both the safety of the operator, being out of harms way, and to allow visibility of the machine from a number of positions, providing more effective service capability.
[0079] The pendant controller 50 preferably comprises an emergency stop button, which should be engaged as a default position, to prevent accidental movement of the machinery.
[0080] Connect power to the apparatus, power is preferably supplied by an external generator supplying 240V, although it is recognised that alternative power sources may be used.
[0081] Release the emergency stop button of the pendant controller 50, thereby providing power to the apparatus 10.
[0082] In the nominal position, the directional solenoid valve 40 directs hydraulic fluid to the return port 66 via the output port 44, but when engaged in either position one or position two, directs hydraulic fluid toward either the extend port 46 or retract port 48.
[0083] The apparatus 10 may cycle hydraulic fluid through the cylinder using the hydraulic pump 20, the operator monitors the pressure readings and listen for any cavitation or aeration. The pressure reading should become stable.
[0084] The direction of movement of the cylinder can be controlled by using the pendant controller 50 to extend and retract the cylinder.
[0085] The operator performs any extend and retract movements as required to service or to confirm correct function of the cylinder. The pressure gauges should be monitored during this process to ensure the cylinder moves freely and without pressure building excessively, which may indicate an obstruction.
[0086] The apparatus 10 allows the extend and retract movements to be performed at a much lower flow rate than would be provided by the machine, thus allowing for greater control.
[0087] The apparatus 10 is preferably powered using single phase power, to enable a smaller generator to be used for portability, as such the motor 30 of the preferred embodiment may not be variable in speed.
[0088] However, it is recognised that alternative embodiments of the present invention exist, where variable speed could be introduced by the use of an appropriate motor 30, or by the use of three phase power.
[0089] Alternatively, a gradual changes in pressure could be effected by using a motor 30 or pump 20 capable of 'inching'.
[0090] The use of the apparatus 10 further allows the extend and retract movements to be performed while the machine is electrically isolated, thereby reducing the risk of injury or harm.
[0091 ] Once the cylinder is functioning as intended the apparatus 10 can be shut down using the stop function of the pendant controller 50, thereby preventing any power being supplied to the machine.
[0092] The cylinder and surrounding hardware should be braced again, to ensure no unwanted movement once the cylinder is depressurised.
[0093] The bleed valve should be opened to relieve excess pressure in the system before disconnecting any hoses.
[0094] The extend and retract connections on the cylinder can be undone and the hoses removed.
[0095] The hydraulic suction hose and the hydraulic return hose are disconnected from the hydraulic reservoir of the machine, and the original cap or blank fittings are reinstalled.
[0096] The hydraulic fluid level should be checked, and topped up if required, as the fluid level may have been reduced during the operation.
[0097] Any safety precautions such as electrical isolation and wheel chocks may now be removed.
[0098] The machine should be tested for correct functionality.
[0099] Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.