US20070251129A1 - Method of operating a hydraulic system for a loader machine - Google Patents
Method of operating a hydraulic system for a loader machine Download PDFInfo
- Publication number
- US20070251129A1 US20070251129A1 US11/786,825 US78682507A US2007251129A1 US 20070251129 A1 US20070251129 A1 US 20070251129A1 US 78682507 A US78682507 A US 78682507A US 2007251129 A1 US2007251129 A1 US 2007251129A1
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- United States
- Prior art keywords
- chamber
- hydraulic
- valve
- check valve
- fluid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2203—Arrangements for controlling the attitude of actuators, e.g. speed, floating function
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
- B66F9/00—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes
- B66F9/06—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes movable, with their loads, on wheels or the like, e.g. fork-lift trucks
- B66F9/065—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes movable, with their loads, on wheels or the like, e.g. fork-lift trucks non-masted
- B66F9/0655—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes movable, with their loads, on wheels or the like, e.g. fork-lift trucks non-masted with a telescopic boom
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
- B66F9/00—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes
- B66F9/06—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes movable, with their loads, on wheels or the like, e.g. fork-lift trucks
- B66F9/075—Constructional features or details
- B66F9/20—Means for actuating or controlling masts, platforms, or forks
- B66F9/22—Hydraulic devices or systems
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2203—Arrangements for controlling the attitude of actuators, e.g. speed, floating function
- E02F9/2207—Arrangements for controlling the attitude of actuators, e.g. speed, floating function for reducing or compensating oscillations
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2217—Hydraulic or pneumatic drives with energy recovery arrangements, e.g. using accumulators, flywheels
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2221—Control of flow rate; Load sensing arrangements
Definitions
- This invention relates to a method of operating a hydraulic system for a loading machine, such as a wheeled loader having a loader arm assembly which carries a working implement and in which the loader arm assembly is connected to the body and which is movable between raised and lowered positions by means of a hydraulic ram.
- a loading machine such as a wheeled loader having a loader arm assembly which carries a working implement and in which the loader arm assembly is connected to the body and which is movable between raised and lowered positions by means of a hydraulic ram.
- a ride improvement system has not been provided hitherto in a loader vehicle including a loader arm assembly connected at, or adjacent to, the rear end of the assembly to the body at, or adjacent to, the rear end of the body so that the loader arm assembly extends forwardly whereby, in a lowered position of the arm assembly, the working implement is disposed in front of the body, where such a vehicle is provided with a hose burst check valve.
- a method of operating a hydraulic system of a loader machine the loader machine having a loader arm assembly connected to a body so that in a lowered position of the loader arm assembly, a working implement carried at an outer end of the loader arm assembly is disposed in front of the body, and which loader arm assembly is movable between raised and lowered positions by means of a hydraulic ram of the hydraulic system
- the hydraulic system further including a ride improvement system including a hydraulic accumulator which is connected to the hydraulic ram, and a selection valve connected to each of a first and second chamber of the hydraulic ram, and a check valve assembly connected between the first chamber and the selection valve such that the check valve, when in a closed condition, prevents fluid under pressure passing from the first chamber to the selection valve, and the check valve assembly having hydraulic fluid responsive means responsive to hydraulic fluid pressure in the second chamber to move the check valve assembly to an open condition, and there being means to connect the hydraulic fluid pressure in the second chamber to the check valve assembly, the
- the selection valve when the selection valve is operated to lower the loader arm assembly, the passage of hydraulic fluid from the second chamber to the low pressure region is prevented, and thus sufficient hydraulic pressure will be provided to the hydraulic pressure sensing means to open the check valve assembly and to permit fluid to pass from the first chamber of the ram, back to the selection valve.
- the method may include moving a first control valve which is connected between the first chamber of the hydraulic ram and the hydraulic accumulator, between a first position in which the passage of hydraulic fluid between the first chamber of the hydraulic ram and the accumulator is permitted and a second position in which passage of hydraulic fluid to the accumulator is prevented.
- a first control valve need not be provided, so that the ride improvement system is potentially permanently in an active condition.
- the method includes moving a control valve which is connected between the second chamber and the low pressure region between a first position in which passage of hydraulic fluid therethrough to the low pressure region is permitted, in which condition the loader arm assembly may be raised, and a second position in which the flow of hydraulic fluid to the low pressure region is prevented, so that the loader arm assembly may be lowered.
- the step of moving the control valve which is connected between the second chamber and the low pressure region between its first and second positions may be carried out purely manually, in a preferred arrangement the selection valve is provided with a switch to sense when the selection valve is operated to lower the loader arm assembly, and wherein the method includes sensing operation of the selection valve to lower the loader arm assembly, and moving at least the second control valve to the second position in response.
- the method step of moving the control valve to permit lowering of the loader arm assembly may be achieved automatically.
- FIG. 1 is a side view of a vehicle according to the invention
- FIG. 2 is a diagrammatic circuit diagram showing the flow of hydraulic: fluid and valve positions in normal operation of the vehicle during lifting of the arm,
- FIG. 3 is a view similar to that of FIG. 2 but showing normal operation during lowering of the arm
- FIG. 4 is a view similar to that of FIG. 2 but showing a travel position of the vehicle with the ride improvement means engaged
- FIG. 5 is a view similar to that of FIG. 4 but showing a boom lift position and ride improvement means engaged.
- FIG. 6 is a view similar to that of FIG. 4 but showing flow of fluid in a boom lower position with the ride improvement means engaged;
- FIG. 7 is a diagrammatic circuit diagram of a second embodiment of the invention.
- a wheeled loader vehicle includes a body 10 supported, in conventional manner, on two pairs of front and rear wheels 11 , 12 each of which is steerable and each of which is driven by a suitable transmission and differential means from an engine which may be disposed as desired on the vehicle.
- the body 10 has a rear end 13 and a front end 14 .
- a loader arm assembly 16 at a position adjacent its rear end, is pivotally mounted to the body 10 adjacent the rear end 13 of the body, about an axis 15 .
- the loader arm assembly 16 in the present example is a two part boom having an outer part 16 a , within which is telescoped an inner part 16 b and which parts are slidable relative to each other by hydraulic ram means so as to provide an extendible loader arm assembly.
- the vehicle may have a two or more part boom or an un-extendible single part boom.
- a working implement 18 At the front end of the boom assembly 16 is a downwardly extending nose part 17 by which a working implement 18 is releasably carried in conventional manner.
- the working implement 18 may be a pair of lifting tines as shown or may be a bucket or any other suitable working implement.
- the loader arm assembly may be connected to the body at or adjacent the rear thereof, by any suitable pivot means disposed at or adjacent the rear of the loader arm assembly.
- the loader arm assembly 16 is pivotable about the axis 15 between raised and lowered positions. In the lowered position working implement 18 is disposed in front of the vehicle front end 14 .
- the loader arm assembly 16 is movable between said raised and lowered positions by a ram assembly 20 , which in the present example includes a single ram.
- the ram assembly 20 in conventional manner, includes a cylinder part 21 and a piston rod 22 .
- the piston rod 22 is connected at one end to a bracket 23 depending downwardly from the underside of the part 16 a of the lowered arm assembly by means of a pivot pin 24 a whilst the cylinder 21 is connected, at its lower end, by a pivot pin 24 b to a part of the body 10 .
- extension and retraction of the piston rod 22 from the cylinder 21 causes pivotal raising and lowering of the arm assembly 16 .
- a first chamber 25 on one side of the piston 27 , which is of cylindrical configuration and a second chamber 26 on the opposite side of the piston 27 , see FIGS. 2 to 5 , to the first chamber 25 and which is of annular configuration in cross section.
- a conventional accumulator means 30 made of, in the present example, steel and connected by a pipe 31 to a first control valve 32 .
- a second control valve 33 is connected by a line 34 including flexible hoses and/or rigid pipes to an hydraulic reservoir or other low pressure area 35 .
- Each control valve 32 , 33 is an electrically operated solenoid valve and which is movable between a first or “at rest” position in which passage of fluid is prevented in one direction of the valve 32 and in both directions in the valve 33 and a second position in which passage of fluid is permitted. Both control valves 32 , 33 are normally spring biased by a spring means 36 to the position in which flow of fluid is prevented as illustrated in FIG. 2 and FIG. 3 .
- a line 38 including a rigid pipe 38 a and a flexible line 38 b , connects the first chamber 25 of the ram 20 to a first port 40 a of a selection valve 40 via a hose burst check valve 39 .
- the first control valve 32 is connected by a line 37 , including a rigid pipe, to the line 38 between ram chamber 25 and the hose burst check valve 39 .
- the hose burst check valve 39 is a pilot valve that is normally maintained closed in the direction to prevent flow of fluid under pressure from the chamber 25 to the valve 40 but it may be opened by supply of pilot pressure on line 41 , including a rigid pipe, from a line 42 , including a rigid pipe 42 a and flexible hoses 42 b which extends between a second port 40 b of the selection valve 40 and the chamber 26 of the ram 20 .
- the line 42 is connected by a line 43 to the second control valve 33 .
- valves 32 and 33 In use, as best shown in FIG. 2 , during normal operation, when it is desired to lift the arm, fluid under pressure is fed from the first port 40 a of the selection valve 40 along the line 38 through the one-way check valve within the hose burst check valve 39 . As boom suspension has not been selected there is no electrical supply to valves 32 and 33 and they remain in the normally closed position. As the telescopic boom 16 is raised, by the supply of fluid to the chamber 25 , fluid under lower pressure is fed from the chamber 26 along line 42 into a port 40 b of the selection valve 40 .
- the valve 33 of course, being, like the valve 32 , maintained in the position shown in FIG. 2 to prevent flow of fluid therethrough by virtue of no electrical supply being supplied to the solenoid thereof.
- valve 40 when it is desired to lower the loader arm assembly the valve 40 is actuated to feed fluid under pressure through port 40 b along line 42 into the chamber 26 and thus fluid under lower pressure is fed from chamber 25 along line 38 through hose burst check valve 39 which is maintained in an open position by virtue of supply of pilot pressure on line 41 which extends from line 42 .
- the system when it is desired to operate the ride improvement means i.e. boom suspension means the system is activated by operation of a suitable electric control so that electrical supply is provided to the valves 32 , 33 to move them from the positions shown FIGS. 2 and 3 to the positions shown in FIGS. 4 to 6 in which passage of hydraulic fluid is permitted.
- a suitable electric control so that electrical supply is provided to the valves 32 , 33 to move them from the positions shown FIGS. 2 and 3 to the positions shown in FIGS. 4 to 6 in which passage of hydraulic fluid is permitted.
- valve 40 when it is desired to raise the loader arm assembly whilst the ride improvement means is engaged, the valve 40 is actuated to feed fluid from port 40 a under pressure along line 38 into the chamber 25 whilst fluid from the chamber 26 passes along the line 42 back to the valve 40 . At the same time the suspension of the arm assembly is suspended by the accumulator 30 as described hereinbefore in connection with the FIG. 4 .
- valve 40 when it is desired to lower the boom whilst the ride improvement means is engaged, the actuation of the valve 40 to raise pressure at port 40 b , by virtue of switch 44 , has the effect of collapsing the electrical signal to valve 33 which becomes closed and so allows pressure to be raised in line 42 which feeds fluid under pressure to chamber 26 , whilst fluid in chamber 25 is fed via line 38 through the hose burst check valve 39 to the port 40 a of the valve 40 .
- the hose burst check valve 39 is maintained open by pilot pressure fluid on line 41 which extends from line 42 .
- valves 32 , 33 and check valve 39 are all disposed on the cylinder 21 , if desired one or more of these components may be positioned as desired and made of material as desired where permitted by local regulations.
- FIG. 7 an alternative embodiment is illustrated. Similar parts to those shown in FIGS. 1 to 6 are indicated by the same reference numerals.
- the first control valve indicated at 32 in the hydraulic system of the previous figures is removed, and the accumulator 30 is connected by the rigid pipe 37 to the line 38 at a point between the hose burst check valve assembly 39 (or check valve assembly 39 ) and the ram assembly 20 .
- the loader vehicle operates similarly to the loader vehicle described with reference to the previous figures, to provide both ride improvement and hose burst protection, by the provision of the host burst protection or check valve assembly 39 .
- the ride improvement system would be permanently “on” or active.
- a first active state when the second control valve 33 is in the “at rest” or first position shown in FIG. 7 , it will be appreciated that it is possible to raise the loader arm assembly 16 by operating the selection valve 40 , to develop pressure in the lines 38 b and 38 connected to the first chamber 25 of the ram assembly 20 with fluid expelled from second chamber 26 passing along line 42 back to the selection valve 40 , the hose burst protection valve assembly 39 maintaining the condition shown in FIG. 7 to provide protection in the event of a hose burst in the line between the hose burst protection valve 39 and the selection valve 40 .
- the loader arm assembly 16 may be lowered by operating the selection valve 40 , to develop pressure in the line 42 to and in the second chamber 26 of the ram assembly 20 . Pressure may be thus developed in the line 42 and second chamber 26 because the second control valve 33 is in its first position i.e. closed to prevent fluid passing from the line 42 to the low pressure region 35 .
- a pilot pressure is transmitted, along line 41 , to the hose burst protection or check valve assembly 39 which thus moves to the condition indicated in FIG. 3 , so that fluid expelled from the first chamber 25 may pass through the hose burst protection or check valve assembly 39 back to and through the selection valve 40 .
- the primary role of the second control valve 33 when in its first “at rest” position is to prevent the flow of pressurised fluid from the line 42 connected to the second chamber 26 of the ram assembly 20 , to the low pressure region 35 , although the particular second control valve 33 shown in the drawings prevents fluid flow in both directions through the valve 33 .
- the second control valve 33 is moved between its first and second positions, e.g. by the operation of a solenoid or other electrically operated actuator, under the control of a manually actuated switch, although preferably under the automatic control of the switch 44 provided on the selector valve 40 , to switch the control valve 33 to its first position so that fluid is prevented from passing to the low pressure region 35 , whenever it is desired to lower the loader arm.
- the second control valve 33 is “at rest” in its second position when fluid flow through the control valve 33 is permitted and an electrical signal is supplied to the control valve 33 to move the control valve to its first position to prevent fluid flow at least to the low pressure region 35 , when the selector valve 40 is operated such as to lower the loader arm.
- the pressure in the accumulator 30 can never exceed the pressure in first chamber 25 .
- the first control valve 32 where provided, is in its second position as seen in FIGS. 4 and 5 , or permanently in the FIG. 7 embodiment, the accumulator 30 will provide at least some ride improvement as the loader vehicle travels over the ground irrespective of the position of the second control valve 33 , as movements of the loader arm at least downwardly will be damped by the action of the accumulator 30 .
- the ride improvement system will be fully active.
- the invention has been described in relation to a wheeled loader vehicle, it will be appreciated that the invention may be applied to any other mobile machine requiring a ride improvement system for a loader arm.
- the invention may be applied to a tracked or partly tacked machine or vehicle, or to a mobile crane.
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Abstract
A method of operating a hydraulic system of a loader arm carrying a working implement, the system having a ride improvement system and a selection valve connected to first and second chambers of a ram which operates the loader arm. A check valve assembly is provided, with the check valve assembly being responsive to pressure changes in the second chamber. The check valve assembly, when closed, prevents fluid from passing between the first chamber to the selection valve. Means are provided communicating the fluid pressure in the second chamber to the check valve, with the means responsive to pressure changes in the second chamber to open the check valve. The selection valve is operable to raise the loader arm with the system arranged to permit passage of fluid between the first chamber and the accumulator while permitting fluid to pass from the second chamber to a low pressure region.
Description
- This invention relates to a method of operating a hydraulic system for a loading machine, such as a wheeled loader having a loader arm assembly which carries a working implement and in which the loader arm assembly is connected to the body and which is movable between raised and lowered positions by means of a hydraulic ram.
- It is known to improve the ride of a wheeled loader by connecting an hydraulic accumulator into the hydraulic hose which feeds hydraulic fluid into said ram means to raise the loader arm assembly. As a result when the wheeled loader is travelling across a site, or when travelling along a road, the loader arm assembly is suspended in spring manner by the accumulator and so the wheeled loader is able to travel with less pitch and bounce than would otherwise have been the case.
- However, such a ride improvement system has not been provided hitherto in a loader vehicle including a loader arm assembly connected at, or adjacent to, the rear end of the assembly to the body at, or adjacent to, the rear end of the body so that the loader arm assembly extends forwardly whereby, in a lowered position of the arm assembly, the working implement is disposed in front of the body, where such a vehicle is provided with a hose burst check valve.
- According to at least one disclosed example of the present invention, we provide a method of operating a hydraulic system of a loader machine, the loader machine having a loader arm assembly connected to a body so that in a lowered position of the loader arm assembly, a working implement carried at an outer end of the loader arm assembly is disposed in front of the body, and which loader arm assembly is movable between raised and lowered positions by means of a hydraulic ram of the hydraulic system, the hydraulic system further including a ride improvement system including a hydraulic accumulator which is connected to the hydraulic ram, and a selection valve connected to each of a first and second chamber of the hydraulic ram, and a check valve assembly connected between the first chamber and the selection valve such that the check valve, when in a closed condition, prevents fluid under pressure passing from the first chamber to the selection valve, and the check valve assembly having hydraulic fluid responsive means responsive to hydraulic fluid pressure in the second chamber to move the check valve assembly to an open condition, and there being means to connect the hydraulic fluid pressure in the second chamber to the check valve assembly, the method including operating the selection valve to raise the loader arm assembly by feeding fluid under pressure to one chamber of the ram and to receive fluid at a lower pressure from the second chamber of the ram, or to lower the loader arm assembly by feeding fluid under pressure to the second chamber of the ram and to receive fluid at a lower pressure from the first chamber of the ram, and wherein the method includes operating the selection valve to raise or lower the loader arm assembly, and when the selection valve means is operated to raise the loader arm assembly, permitting the passage of hydraulic fluid between the first chamber of the hydraulic ram and the accumulator, and whilst permitting the passage of hydraulic fluid from the second chamber to a low pressure region.
- Desirably, when the selection valve is operated to lower the loader arm assembly, the passage of hydraulic fluid from the second chamber to the low pressure region is prevented, and thus sufficient hydraulic pressure will be provided to the hydraulic pressure sensing means to open the check valve assembly and to permit fluid to pass from the first chamber of the ram, back to the selection valve.
- If desired, the method may include moving a first control valve which is connected between the first chamber of the hydraulic ram and the hydraulic accumulator, between a first position in which the passage of hydraulic fluid between the first chamber of the hydraulic ram and the accumulator is permitted and a second position in which passage of hydraulic fluid to the accumulator is prevented. However in another arrangement, such a first control valve need not be provided, so that the ride improvement system is potentially permanently in an active condition.
- The method includes moving a control valve which is connected between the second chamber and the low pressure region between a first position in which passage of hydraulic fluid therethrough to the low pressure region is permitted, in which condition the loader arm assembly may be raised, and a second position in which the flow of hydraulic fluid to the low pressure region is prevented, so that the loader arm assembly may be lowered.
- Although the step of moving the control valve which is connected between the second chamber and the low pressure region between its first and second positions may be carried out purely manually, in a preferred arrangement the selection valve is provided with a switch to sense when the selection valve is operated to lower the loader arm assembly, and wherein the method includes sensing operation of the selection valve to lower the loader arm assembly, and moving at least the second control valve to the second position in response. Thus, in accordance with the disclosed example, the method step of moving the control valve to permit lowering of the loader arm assembly may be achieved automatically.
- Embodiments of the invention will now be described with reference to the accompanying drawings wherein:
-
FIG. 1 is a side view of a vehicle according to the invention, -
FIG. 2 is a diagrammatic circuit diagram showing the flow of hydraulic: fluid and valve positions in normal operation of the vehicle during lifting of the arm, -
FIG. 3 is a view similar to that ofFIG. 2 but showing normal operation during lowering of the arm, -
FIG. 4 is a view similar to that ofFIG. 2 but showing a travel position of the vehicle with the ride improvement means engaged, -
FIG. 5 is a view similar to that ofFIG. 4 but showing a boom lift position and ride improvement means engaged. -
FIG. 6 is a view similar to that ofFIG. 4 but showing flow of fluid in a boom lower position with the ride improvement means engaged; -
FIG. 7 is a diagrammatic circuit diagram of a second embodiment of the invention. - Referring to the drawings, a wheeled loader vehicle includes a
body 10 supported, in conventional manner, on two pairs of front andrear wheels body 10 has arear end 13 and afront end 14. Aloader arm assembly 16, at a position adjacent its rear end, is pivotally mounted to thebody 10 adjacent therear end 13 of the body, about anaxis 15. Theloader arm assembly 16 in the present example, is a two part boom having anouter part 16 a, within which is telescoped aninner part 16 b and which parts are slidable relative to each other by hydraulic ram means so as to provide an extendible loader arm assembly. If desired the vehicle may have a two or more part boom or an un-extendible single part boom. - At the front end of the
boom assembly 16 is a downwardly extendingnose part 17 by which a workingimplement 18 is releasably carried in conventional manner. If desired, the workingimplement 18 may be a pair of lifting tines as shown or may be a bucket or any other suitable working implement. - The loader arm assembly may be connected to the body at or adjacent the rear thereof, by any suitable pivot means disposed at or adjacent the rear of the loader arm assembly.
- The
loader arm assembly 16 is pivotable about theaxis 15 between raised and lowered positions. In the loweredposition working implement 18 is disposed in front of thevehicle front end 14. Theloader arm assembly 16 is movable between said raised and lowered positions by aram assembly 20, which in the present example includes a single ram. Theram assembly 20, in conventional manner, includes acylinder part 21 and apiston rod 22. Thepiston rod 22 is connected at one end to abracket 23 depending downwardly from the underside of thepart 16 a of the lowered arm assembly by means of apivot pin 24 a whilst thecylinder 21 is connected, at its lower end, by apivot pin 24 b to a part of thebody 10. Obviously extension and retraction of thepiston rod 22 from thecylinder 21 causes pivotal raising and lowering of thearm assembly 16. - Within the
cylinder 21 is afirst chamber 25, on one side of thepiston 27, which is of cylindrical configuration and asecond chamber 26 on the opposite side of thepiston 27, see FIGS. 2 to 5, to thefirst chamber 25 and which is of annular configuration in cross section. Mounted on thecylinder 21 is a conventional accumulator means 30 made of, in the present example, steel and connected by apipe 31 to afirst control valve 32. Asecond control valve 33 is connected by aline 34 including flexible hoses and/or rigid pipes to an hydraulic reservoir or otherlow pressure area 35. - Each
control valve valve 32 and in both directions in thevalve 33 and a second position in which passage of fluid is permitted. Bothcontrol valves FIG. 2 andFIG. 3 . - A
line 38, including arigid pipe 38 a and aflexible line 38 b, connects thefirst chamber 25 of theram 20 to afirst port 40 a of aselection valve 40 via a hoseburst check valve 39. Thefirst control valve 32 is connected by aline 37, including a rigid pipe, to theline 38 betweenram chamber 25 and the hoseburst check valve 39. The hoseburst check valve 39 is a pilot valve that is normally maintained closed in the direction to prevent flow of fluid under pressure from thechamber 25 to thevalve 40 but it may be opened by supply of pilot pressure online 41, including a rigid pipe, from aline 42, including arigid pipe 42 a andflexible hoses 42 b which extends between asecond port 40 b of theselection valve 40 and thechamber 26 of theram 20. Theline 42 is connected by aline 43 to thesecond control valve 33. - In use, as best shown in
FIG. 2 , during normal operation, when it is desired to lift the arm, fluid under pressure is fed from thefirst port 40 a of theselection valve 40 along theline 38 through the one-way check valve within the hoseburst check valve 39. As boom suspension has not been selected there is no electrical supply tovalves telescopic boom 16 is raised, by the supply of fluid to thechamber 25, fluid under lower pressure is fed from thechamber 26 alongline 42 into aport 40 b of theselection valve 40. Thevalve 33, of course, being, like thevalve 32, maintained in the position shown inFIG. 2 to prevent flow of fluid therethrough by virtue of no electrical supply being supplied to the solenoid thereof. - Referring now to
FIG. 3 , when it is desired to lower the loader arm assembly thevalve 40 is actuated to feed fluid under pressure throughport 40 b alongline 42 into thechamber 26 and thus fluid under lower pressure is fed fromchamber 25 alongline 38 through hoseburst check valve 39 which is maintained in an open position by virtue of supply of pilot pressure online 41 which extends fromline 42. - Referring now to
FIG. 4 , when it is desired to operate the ride improvement means i.e. boom suspension means the system is activated by operation of a suitable electric control so that electrical supply is provided to thevalves FIGS. 2 and 3 to the positions shown in FIGS. 4 to 6 in which passage of hydraulic fluid is permitted. - In this position fluid can flow both to the
accumulator 30 and also to thereservoir 35 in accordance with the external forces imposed on thepiston 27 to displace fluid to or fromchambers FIG. 4 . As a result the loader arm is supported by the action of the accumulator on the hydraulic fluid and it is, in effect, sprung. - Referring now to
FIG. 5 , when it is desired to raise the loader arm assembly whilst the ride improvement means is engaged, thevalve 40 is actuated to feed fluid fromport 40 a under pressure alongline 38 into thechamber 25 whilst fluid from thechamber 26 passes along theline 42 back to thevalve 40. At the same time the suspension of the arm assembly is suspended by theaccumulator 30 as described hereinbefore in connection with theFIG. 4 . - Referring now to
FIG. 6 , when it is desired to lower the boom whilst the ride improvement means is engaged, the actuation of thevalve 40 to raise pressure atport 40 b, by virtue ofswitch 44, has the effect of collapsing the electrical signal tovalve 33 which becomes closed and so allows pressure to be raised inline 42 which feeds fluid under pressure tochamber 26, whilst fluid inchamber 25 is fed vialine 38 through the hoseburst check valve 39 to theport 40 a of thevalve 40. The hoseburst check valve 39 is maintained open by pilot pressure fluid online 41 which extends fromline 42. - Whilst in this example the
accumulator 30,valves check valve 39 are all disposed on thecylinder 21, if desired one or more of these components may be positioned as desired and made of material as desired where permitted by local regulations. - Referring now to
FIG. 7 an alternative embodiment is illustrated. Similar parts to those shown in FIGS. 1 to 6 are indicated by the same reference numerals. - In this example, the first control valve indicated at 32 in the hydraulic system of the previous figures, is removed, and the
accumulator 30 is connected by therigid pipe 37 to theline 38 at a point between the hose burst check valve assembly 39 (or check valve assembly 39) and theram assembly 20. - The loader vehicle operates similarly to the loader vehicle described with reference to the previous figures, to provide both ride improvement and hose burst protection, by the provision of the host burst protection or
check valve assembly 39. - However, it will be appreciated that without the presence of the
first control valve 32 which is moveable as described above to a second position to prevent the flow of hydraulic fluid to theaccumulator 30, the ride improvement system would be permanently “on” or active. - In a first active state, when the
second control valve 33 is in the “at rest” or first position shown inFIG. 7 , it will be appreciated that it is possible to raise theloader arm assembly 16 by operating theselection valve 40, to develop pressure in thelines first chamber 25 of theram assembly 20 with fluid expelled fromsecond chamber 26 passing alongline 42 back to theselection valve 40, the hose burstprotection valve assembly 39 maintaining the condition shown inFIG. 7 to provide protection in the event of a hose burst in the line between the hose burstprotection valve 39 and theselection valve 40. - Moreover in the first active state, the
loader arm assembly 16 may be lowered by operating theselection valve 40, to develop pressure in theline 42 to and in thesecond chamber 26 of theram assembly 20. Pressure may be thus developed in theline 42 andsecond chamber 26 because thesecond control valve 33 is in its first position i.e. closed to prevent fluid passing from theline 42 to thelow pressure region 35. Thus a pilot pressure is transmitted, alongline 41, to the hose burst protection orcheck valve assembly 39 which thus moves to the condition indicated inFIG. 3 , so that fluid expelled from thefirst chamber 25 may pass through the hose burst protection orcheck valve assembly 39 back to and through theselection valve 40. - In a second active state, whilst the
line 38 between the hose burst protection orcheck valve assembly 39 and theram assembly 20 is connected to theaccumulator 30 by virtue of the absence of thefirst control valve 32, thesecond control valve 33 is moved to second position shown inFIG. 4 when fluid flow from theline 42 between thesecond chamber 25 of theram assembly 40 and theselection valve 40, through thesecond control valve 33 to thelow pressure region 35, is permitted. In this state, although ride improvement is provided as theaccumulator 30 is still connected to theline 38 between the host burst protection orcheck valve assembly 39, and thefirst chamber 25 of theram assembly 20, and the loader arm may be lifted by applying pressure tolines 38 b/38. However, fluid expelled from thesecond chamber 26 of theram assembly 20 may pass to thelow pressure region 35 through thesecond control valve 33. - It will be appreciated that the primary role of the
second control valve 33 when in its first “at rest” position is to prevent the flow of pressurised fluid from theline 42 connected to thesecond chamber 26 of theram assembly 20, to thelow pressure region 35, although the particularsecond control valve 33 shown in the drawings prevents fluid flow in both directions through thevalve 33. - In the embodiment of
FIG. 7 preferably thesecond control valve 33 is moved between its first and second positions, e.g. by the operation of a solenoid or other electrically operated actuator, under the control of a manually actuated switch, although preferably under the automatic control of theswitch 44 provided on theselector valve 40, to switch thecontrol valve 33 to its first position so that fluid is prevented from passing to thelow pressure region 35, whenever it is desired to lower the loader arm. Desirably in this embodiment, thesecond control valve 33 is “at rest” in its second position when fluid flow through thecontrol valve 33 is permitted and an electrical signal is supplied to thecontrol valve 33 to move the control valve to its first position to prevent fluid flow at least to thelow pressure region 35, when theselector valve 40 is operated such as to lower the loader arm. - In each of the embodiments described, by virtue of either the one way check valve within the first control valve 32 (in the embodiments shown in FIGS. 1 to 6) or the direct connection between the
accumulator 30 and theline 38 between the hose burst protection orcheck valve assembly 39 and thefirst chamber 25 of theram assembly 20, the pressure in theaccumulator 30 can never exceed the pressure infirst chamber 25. When thefirst control valve 32 where provided, is in its second position as seen inFIGS. 4 and 5 , or permanently in theFIG. 7 embodiment, theaccumulator 30 will provide at least some ride improvement as the loader vehicle travels over the ground irrespective of the position of thesecond control valve 33, as movements of the loader arm at least downwardly will be damped by the action of theaccumulator 30. In each embodiment, when thesecond chamber 26 of theram 20 is connected to thelow pressure region 35, when thesecond control valve 33 is in its second position, the ride improvement system will be fully active. - In each mode of operation described above, in the event of a host burst in the
line 38 b between the host burst protection ofcheck valve assembly 39 and theselection valve 40 when highly pressurised, e.g. during lifting, or in the hose between where thesecond control valve 33 and theline 42 to theselection valve 40 are connected when highly pressurised, e.g. during lowering, the hose burst protection orcheck valve assembly 39 will be closed or close, to prevent the escape of pressurised fluid from theline 38 a between thefirst chamber 25 and the hose burst protection orcheck valve assembly 39, so that the loader arm is prevented from collapsing and thus possible creating an unstable and possibly dangerous situation. - Although the invention has been described in relation to a wheeled loader vehicle, it will be appreciated that the invention may be applied to any other mobile machine requiring a ride improvement system for a loader arm. For example the invention may be applied to a tracked or partly tacked machine or vehicle, or to a mobile crane.
- The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.
Claims (8)
1-6. (canceled)
7. A hydraulic system for a wheeled loader having a loader arm assembly which is movable between raised and lowered positions by means of a hydraulic actuator device, the system comprising:
a selection valve having first and second ports for directing hydraulic fluid to a cylinder, the cylinder having first and second chambers, the first chamber connected to the first port and the second chamber connected to the second port;
a hydraulic accumulator connected to the hydraulic actuator device between the first port and the first chamber;
a first control valve connected to the hydraulic actuator device between the hydraulic accumulator and the first chamber;
a second control valve connected to the hydraulic actuator device between the second port and the second chamber, the second control valve further connected to a hydraulic reservoir; and
a hose burst check valve connected to the hydraulic actuator device between the first port and the hydraulic accumulator;
wherein the first control valve is movable between a first position in which passage of hydraulic fluid is permitted only from the hydraulic accumulator toward the first chamber and a second position in which passage of hydraulic fluid is permitted in bi-directionally between the hydraulic accumulator and the first chamber,
the second control valve is movable between a first position in which passage of hydraulic fluid through the second control valve is prevented and a second position in which passage of hydraulic fluid through the second control valve is permitted, and
the hose burst check valve normally allows one-way hydraulic fluid flow from the first port to the first chamber, but the hose burst check valve is arranged to permit two-way hydraulic fluid flow between the first chamber and the first port when hydraulic fluid is directed from the second port to the hose burst check valve.
8. The system according to claim 7 wherein the hose burst check valve is a pilot valve.
9. The system according to claim 7 wherein the selection valve is manually operable.
10. The system according to claim 7 wherein the first and second control valves are electrically operated solenoid valves to which current is supplied by a manually operable switch means.
11. The system according to claim 7 wherein the first and second control valves are biased towards the first position.
12. The system according to claim 11 wherein the first and second control valves are spring biased towards the first position.
13. The system according to claim 7 wherein at least one of said accumulator, control valves, check valve assembly and connecting pipes are made of metal.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11/786,825 US20070251129A1 (en) | 2000-05-25 | 2007-04-13 | Method of operating a hydraulic system for a loader machine |
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0012602.9 | 2000-05-25 | ||
GB0012602A GB2365407B (en) | 2000-05-25 | 2000-05-25 | Hydraulic system for wheeled loader |
US09/866,311 US7089734B2 (en) | 2000-05-25 | 2001-05-25 | Hydraulic system for wheeled loader |
US10/885,325 US7204086B2 (en) | 2000-05-25 | 2004-07-06 | Method of operating a hydraulic system for a loader machine |
US11/786,825 US20070251129A1 (en) | 2000-05-25 | 2007-04-13 | Method of operating a hydraulic system for a loader machine |
Related Parent Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/866,311 Continuation-In-Part US7089734B2 (en) | 2000-05-25 | 2001-05-25 | Hydraulic system for wheeled loader |
US10/885,325 Continuation US7204086B2 (en) | 2000-05-25 | 2004-07-06 | Method of operating a hydraulic system for a loader machine |
Publications (1)
Publication Number | Publication Date |
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US20070251129A1 true US20070251129A1 (en) | 2007-11-01 |
Family
ID=34066583
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
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US10/885,325 Expired - Lifetime US7204086B2 (en) | 2000-05-25 | 2004-07-06 | Method of operating a hydraulic system for a loader machine |
US11/786,825 Abandoned US20070251129A1 (en) | 2000-05-25 | 2007-04-13 | Method of operating a hydraulic system for a loader machine |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
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US10/885,325 Expired - Lifetime US7204086B2 (en) | 2000-05-25 | 2004-07-06 | Method of operating a hydraulic system for a loader machine |
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US (2) | US7204086B2 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7827787B2 (en) | 2007-12-27 | 2010-11-09 | Deere & Company | Hydraulic system |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7204086B2 (en) * | 2000-05-25 | 2007-04-17 | J.C Bamford Excavators Limited | Method of operating a hydraulic system for a loader machine |
DE102005038333A1 (en) * | 2005-08-11 | 2007-02-15 | Deere & Company, Moline | Hydraulic arrangement |
JP2016530455A (en) * | 2013-09-16 | 2016-09-29 | リカルド レラ ゴメス | Hydraulic accumulator and method for recovering energy in a hydraulic system |
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Also Published As
Publication number | Publication date |
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US20050011189A1 (en) | 2005-01-20 |
US7204086B2 (en) | 2007-04-17 |
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