WO2007022546A1 - Control systems for earth working equipment - Google Patents

Control systems for earth working equipment Download PDF

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Publication number
WO2007022546A1
WO2007022546A1 PCT/ZA2005/000122 ZA2005000122W WO2007022546A1 WO 2007022546 A1 WO2007022546 A1 WO 2007022546A1 ZA 2005000122 W ZA2005000122 W ZA 2005000122W WO 2007022546 A1 WO2007022546 A1 WO 2007022546A1
Authority
WO
WIPO (PCT)
Prior art keywords
earth working
components
assembly
hydraulically operable
switch means
Prior art date
Application number
PCT/ZA2005/000122
Other languages
French (fr)
Inventor
Adolf Christiaan Ellis
Original Assignee
Adolf Christiaan Ellis
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Adolf Christiaan Ellis filed Critical Adolf Christiaan Ellis
Priority to PCT/ZA2005/000122 priority Critical patent/WO2007022546A1/en
Publication of WO2007022546A1 publication Critical patent/WO2007022546A1/en

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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
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F3/00—Dredgers; Soil-shifting machines
    • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
    • E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
    • E02F3/36—Component parts
    • E02F3/42—Drives for dippers, buckets, dipper-arms or bucket-arms
    • E02F3/422—Drive systems for bucket-arms, front-end loaders, dumpers or the like
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F3/00—Dredgers; Soil-shifting machines
    • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
    • E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
    • E02F3/36—Component parts
    • E02F3/42—Drives for dippers, buckets, dipper-arms or bucket-arms
    • E02F3/425—Drive systems for dipper-arms, backhoes or the like
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F3/00—Dredgers; Soil-shifting machines
    • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
    • E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
    • E02F3/36—Component parts
    • E02F3/42—Drives for dippers, buckets, dipper-arms or bucket-arms
    • E02F3/43—Control of dipper or bucket position; Control of sequence of drive operations
    • E02F3/431—Control of dipper or bucket position; Control of sequence of drive operations for bucket-arms, front-end loaders, dumpers or the like
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F3/00—Dredgers; Soil-shifting machines
    • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
    • E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
    • E02F3/36—Component parts
    • E02F3/42—Drives for dippers, buckets, dipper-arms or bucket-arms
    • E02F3/43—Control of dipper or bucket position; Control of sequence of drive operations
    • E02F3/435—Control of dipper or bucket position; Control of sequence of drive operations for dipper-arms, backhoes or the like
    • 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
    • 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
    • E02F9/226—Safety arrangements, e.g. hydraulic driven fans, preventing cavitation, leakage, overheating

Definitions

  • This invention relates to earth working equipment.
  • the invention relates to control systems for controlling an earth working assembly of earth working equipment.
  • Earth working assemblies such as, for example, shovel arrangements carried on remote ends of arms, and the like, are often used to work the earth. Such assemblies are often mounted on vehicles, such as, for example, bull-dozers, and the like.
  • an earth working assembly including at least two components mounted for displacement relative to each other within a range of travel, at least one hydraulically operable piston and cylinder assembly operatively connected between the at least two components and arranged to cause displacement of the components within the range of travel and switch means arranged selectively to be switched to cause pressure in the at least one hydraulically operable piston and cylinder assembly to be relieved thereby to permit one of the at least two components to gravitate relative to the other of the at least two components.
  • One of the at least two components may be a shovel arrangement mounted for angular displacement relative to the other of the at least two components.
  • the at least one hydraulically operable piston and cylinder assembly may be arranged selectively to be pressurized so as to cause the shovel arrangement to displace angularly away from the other of the at least two components.
  • the switch means may then be arranged to cause pressure in the at least one hydraulically operable piston and cylinder assembly to be relieved so as to permit the shovel arrangement to gravitate angularly toward the other of the at least two components.
  • the switch means may be arranged to connect a rod-end chamber and a head-end chamber of the at least one hydraulically operable piston and cylinder assembly together in flow communication so as to permit pressure in the at least one hydraulically operable piston and cylinder assembly to be relieved by enabling fluid flow between the rod-end chamber and the head-end chamber.
  • the switch means may be arranged to permit fluid flow from a fluid source to the hydraulically operable piston and cylinder assembly so as to compensate for volume variation in the rod-end chamber as the shovel arrangement gravitates angularly toward the other of the at least two components.
  • the earth working assembly may include a suction valve through which the switch means is arranged to permit fluid flow from the fluid source to the hydraulically operable piston and cylinder assembly.
  • the switch means may be arranged to permit the at least one hydraulically operable piston and cylinder assembly to be pressurized when the shovel arrangement is at an end of the range of travel after having gravitated toward the other of the at least two components thereby to hold the shovel arrangement at that end of the range of travel under pressure.
  • the earth working assembly may include two hydraulically operable piston and cylinder assemblies operatively connected between the shovel arrangement and the other of the at least two components. Both of the hydraulically operable piston and cylinder assemblies may be arranged to be pressurized so as to cause the shovel arrangement to displace angularly away from the other of the at least two components. The switch means may then be arranged to cause pressure in both hydraulically operable piston and cylinder assemblies to be relieved so as to permit the shovel arrangement to gravitate angularly toward the other of the at least two components.
  • the switch means may be arranged to connect a rod-end chamber and a head-end chamber of both piston and cylinder assemblies together in flow communication so as to permit pressure in both hydraulically operable piston and cylinder assemblies to be relieved by enabling fluid flow between the rod-end chambers and the head-end chambers.
  • the switch means may be arranged to permit fluid flow from a fluid source to the hydraulically operable piston and cylinder assemblies so as to compensate for volume variation in the rod-end chambers as the shovel arrangement gravitates angularly toward the other of the at least two components.
  • the earth working assembly may include a suction valve through which the switch means is arranged to permit fluid flow from the fluid source to the hydraulically operable piston and cylinder assemblies.
  • the switch means may be arranged to permit both hydraulically operable piston and cylinder assemblies to be pressurized when the shovel arrangement is at an end of the range of travel after having gravitated toward the other of the at least two components thereby to hold the shovel arrangement at that end of the range of travel under pressure.
  • the earth working assembly may include a main control valve for controlling supply pressure to the, or each, hydraulically operable piston and cylinder assembly.
  • the switch means may then be arranged to cause pressure supply from the main control valve to the, or each, hydraulically operable piston and cylinder assembly to be interrupted when the shovel arrangement gravitates angularly toward the other of the at least two components.
  • the other of the at least two components may be a dozer.
  • the switch means may include a hydraulic valve. Instead, the switch means may include an electrical switch.
  • One of the at least two components may be a dozer arranged to be angularly displaceable relative to the other of the at least two components.
  • the at least one hydraulically operable piston and cylinder assembly may be arranged to be pressurized so as to cause the dozer selectively to displace angularly toward and away from the other of the at least two components.
  • the switch means may then be arranged to be switched when the dozer is at a position at one end of the range of travel thereby to cause pressure in the at least one hydraulically operable piston and cylinder assembly to be relieved so as to permit the dozer to gravitate relative to the other of the at least two components.
  • the switch means may be arranged to connect a rod-end chamber and a head-end chamber of the at least one hydraulically operable piston and cylinder assembly together in flow communication thereby to permit pressure in the at least one hydraulically operable piston and cylinder assembly to be relieved.
  • the earth working assembly may include two hydraulically operable piston and cylinder assemblies operatively connected between the dozer and the other of the at least two components. Both hydraulically operable piston and cylinder assemblies may be arranged to be pressurized so as to cause the dozer selectively to displace angularly toward and away from the other of the at least two components.
  • the switch means may then be arranged to be switched when the dozer is at a position at one end of the range of travel thereby to cause pressure in both hydraulically operable piston and cylinder assemblies to be relieved so as to permit the dozer to gravitate relative to the other of the at least two components.
  • the switch means may be arranged to connect a rod-end chamber and a head-end chamber of both piston and cylinder assemblies together in flow communication as to permit pressure in both hydraulically operable piston and cylinder assemblies to be relieved.
  • the switch means may be operatively mounted relative to the dozer and the other of the at least two components so as to be switched in response to the dozer being displaced toward the other of the at least two components to the position at the one end of the range of travel.
  • the earth working assembly may include a main control valve for controlling supply pressure to the, or each, piston and cylinder assembly.
  • the switch means may then be operatively associated with the main control valve so as to cause the main control valve to interrupt pressure supply to the, or each, piston and cylinder assembly in response to the at least two components being displaced to the position at the one end of the range of travel.
  • the other of the at least two components may be an arm.
  • the switch means may include a hydraulic valve. Instead, the switch means may include an electrical switch.
  • an earth working assembly including an earth working head defining at least two components mounted for displacement relative to each other within a range of travel, an arm on which the earth working head is mounted for displacement relative to the arm, a body on which the arm is mounted for displacement relative to the body, at least one hydraulically operable piston and cylinder assembly operatively connected between the at least two components and arranged to control displacement of the components relative to each other, at least one hydraulically operable piston and cylinder assembly operatively connected between the earth working head and the arm and arranged to control displacement of the earth working head relative to the arm, at least one hydraulically operable piston and cylinder assembly operatively connected between the arm and the body and arranged to control displacement of the arm relative to the body and switch means arranged to be switched when the at least two components are displaced relative to each other to a position at one end of the range of travel, the switch means being arranged to interrupt a pressure supply to at least one
  • One of the at least two components defined by the earth working head may be a shovel arrangement mounted for angular displacement relative to the other of the at least two components.
  • the one end of the range of travel may correspond with a closed condition of the earth working head in which the shovel arrangement is angularly positioned immediately adjacent the other of the at least two components.
  • the earth working assembly may include two hydraulically operable piston and cylinder assemblies operatively connected between the arm and the body. Both hydraulically operable piston and cylinder assemblies may be arranged to control displacement of the arm relative to the body.
  • the earth working assembly may include a main control valve for controlling supply pressure to the, or each, hydraulically operable piston and cylinder assembly operatively connected between the arm and the body.
  • the switch means may then be operatively associated with the main control valve so as to cause the main control valve to interrupt pressure supply to the, or each, hydraulically operable piston and cylinder assembly operatively connected between the arm and the body in response to the shovel arrangement being angularly displaced away from the position at the one end of the range of travel.
  • the other of the at least two components of the earth working head may be in the form of a dozer.
  • the body may be in the form of a boom.
  • the earth working assembly may further include a travel brake.
  • the switch means may be arranged to inhibit release of the travel brake in response to the at least two components being displaced away from the position at the one end of the range of travel.
  • the earth working assembly may include two hydraulically operable piston and cylinder assemblies operatively connected between the at least two components defined by the working head, both hydraulically operable piston and cylinder assemblies being arranged to control displacement of the at least two components relative to each other.
  • the switch means may include a hydraulic valve. Instead, the switch means may include an electrical switch.
  • Figure 1 shows a schematic side view of part of an earth working assembly, a dozer of an earth working head of the earth working assembly being shown in a fully retracted condition;
  • Figure 2 shows a schematic side view of the part of the earth working assembly shown Figure 1, the dozer of the earth working head of the earth working assembly being shown in an extended condition;
  • Figure 3 shows, at an enlarge scale, a schematic side view of the earth working head of the earth working assembly shown in Figures 1 and 2, a jaw of the earth working head being shown in an open condition;
  • Figure 4 shows a schematic hydraulic diagram of a hydraulic circuit in accordance with one embodiment of the invention, the hydraulic circuit being arranged to regulate opening and closing of the jaw shown in Figure 3, the hydraulic circuit corresponding to the jaw being in an open condition;
  • Figure 5 A shows a schematic hydraulic diagram of the hydraulic circuit shown in Figure 4, the hydraulic circuit corresponding to the jaw being closed;
  • Figure 5B shows a schematic hydraulic diagram of the hydraulic circuit shown in Figure 4, the hydraulic circuit corresponding to the jaw being in a fully closed condition;
  • Figure 6 shows a schematic hydraulic diagram of a hydraulic circuit in accordance with one embodiment of the invention, the hydraulic circuit being arranged to regulate the extension and retraction of the earth working head of the earth working assembly shown in Figures 1 and 2 of the drawings, the hydraulic circuit corresponding to the earth working head being in an extended condition; and
  • Figure 7 shows a schematic hydraulic diagram of the hydraulic circuit shown in Figure 6, the hydraulic circuit corresponding to the earth working head being in a fully retracted condition.
  • part of an earth working assembly is generally indicated by reference numeral 10.
  • the part of the earth working assembly 10 can form part of an earth working vehicle, such as, for example, a bull dozer, a wheel dozer, or the like.
  • the part of the working assembly 10 includes a body, or boom 12 and a pivotal connection 14 secured relative to a super structure (not shown) of the rest of the earth working assembly.
  • the boom 12 is pivotally mounted on the super structure to be angularly displaceable relative to the super structure as indicated by arrows BB.
  • a pair of boom piston and cylinder assemblies 19, 19 are provided, only one of which is shown in Figures 1 and 2 of the drawings.
  • An arm component, or stick 16 is pivotally connected to the boom 12 by means of a pivotal connection 18.
  • the stick 16 is angularly displaceable relative to the boom 12 about the pivotal connection 18 as indicated by arrows AA.
  • Angular displacement of the stick 16 relative to the boom 12 is controlled by a pair of stick piston and cylinder assemblies 20, 20, only one of which is shown in Figures 1 and 2 of the drawings.
  • One end 20.1 of the stick piston and cylinder assembly 20 is pivotally connected to the boom 12 by means of a pivotal connection 22.
  • An opposed end 20.2 of the stick piston and cylinder assembly 20 is pivotally connected to the stick 16 by means of a pivotal connection 24.
  • the part of the earth working assembly 10 further includes an earth working head, or bucket, generally indicated by reference numeral 26.
  • the earth working head 26 defines a component in the form of a dozer 28.
  • the dozer 28 is connected to the stick 16 by means of a pivotal connection 30 to be angularly displaceable relative to the stick 16 about the pivotal connection 30 as indicated by arrows CC.
  • One end 32.1 of the bucket piston and cylinder assembly 32 is pivotally connected to the dozer 28 by means of a pivotal connection 34.
  • An opposed end 32.2 of the bucket piston and cylinder assembly 32 is pivotally connected to the boom 12 by means of a pivotal connection 36.
  • a stop arrangement generally indicated at 38, stops the dozer 28 relative to the stick 16 when in a fully retracted position.
  • the stop arrangement 38 defines a stop 38.1 on the dozer 28 and an associated stop 38.2 on the stick 16.
  • the earth working head 26 defines another component in the form of a shovel arrangement 40.
  • the shovel arrangement 40 and the dozer 28 together define a jaw generally indicated by reference numeral 41.
  • the shovel arrangement 40 is pivotally connected to the dozer 28 by means of a pivotal connection 42 to be angularly displaceable within a range of travel about the pivotal connection 42 as indicated by arrows DD.
  • a pair of jaw piston and cylinder assemblies 42, 42 is provided, only one of which is shown in Figure 3.
  • One end 42.1 of the jaw piston and cylinder assembly 42 is pivotally connected to the shovel arrangement 40 at 44.
  • FIG. 4 A and 5B of the drawings a hydraulic circuit of the earth working assembly, in accordance with one embodiment of the invention, is generally indicated by reference numeral 110.
  • reference numeral 110 a hydraulic circuit of the earth working assembly, in accordance with one embodiment of the invention, is generally indicated by reference numeral 110.
  • FIGs 4, 5 A and 5B like reference numerals have been used to designate similar parts, unless otherwise stated.
  • the hydraulic circuit 110 is arranged to inhibit the earth working assembly from being operated to work the earth when the jaw 41 is not in a closed condition thereby to inhibit such strain on the jaw 41 and the jaw piston and cylinder assemblies 42, 42.
  • the hydraulic circuit 110 includes a float valve 112, a suction valve 114, a limit valve 116, a manifold 118, dump valves 120, 120 and a sensing valve 123.
  • the hydraulic circuit 110 is arranged to prevent the stick piston and cylinder assemblies 20, 20, and a travel brake assembly (not shown) from being operated unless the jaw 41 is in a closed condition, as indicated in Figure 1 of the drawings. This will now be described.
  • the limit valve 116 can be mounted relative to one of the jaw piston and cylinder assemblies 42, 42.
  • the limit valve 116 is typically arranged to be switched, as indicated in Figure 5B of the drawings, when the jaw 41 is in a closed condition. This can typically be achieved by providing an appropriate arm, or bracket 50 mounted relative to the piston rod 42.3 of the one of the jaw piston and cylinder assemblies 42 such that when the piston rod 42.3 of the one of the jaw piston and cylinder assemblies 42 is at an extended position in which the jaw 41 is closed, the arm 50 causes the limit valve 116 to switch.
  • a pilot pressure line 122 is caused to be depressurized, as indicated at 124.
  • the pilot pressure line 122 is operatively connected to pilot pressure lines 126, 128, 130 through the manifold 118. Accordingly, when the pilot pressure line 122 is depressurized, the pilot pressure lines 126, 128, 130 are depressurized as well.
  • the dump valves 120, 120 and the sensing valve 123 are operatively connected to main pilot pressure lines 134, 136, 132 respectively.
  • the main pilot pressure line 132 is operatively connected to the float valve 112.
  • the main pilot pressure line 134 is operatively connected to a spool (not shown) in a main control valve (not shown) operatively connected in a hydraulic line arranged to enable the stick piston and cylinder assemblies 20, 20 to be pressurized.
  • the main pilot pressure line 136 is operatively connected to a travel brake assembly (not shown) to enable the travel brake assembly to be released.
  • a travel brake assembly not shown
  • the pilot pressure lines 126, 128, 130 are depressurized as indicated in Figure 5B of the drawings, the main pilot pressure lines 134, 136 are operable to permit operation of the stick piston and cylinder assemblies 20, 20 and release of the travel brake assembly (not shown). Accordingly, when the jaw 41 is closed, angular displacement of the stick 16 and release of the travel brake assembly (not shown) is enabled.
  • the main pilot pressure lines 134, 136 are depressurized thereby to prevent operation of the stick piston and cylinder assemblies 20, 20 and the travel brake assembly (not shown). In this way, angular displacement of the stick 16 and release of the travel brake assembly (not shown) is disabled in response to the jaw 41 being in an open condition. Accordingly, an operator of the earth working assembly can only use the assembly to dig if the jaw 41 is in a closed condition.
  • an electrical proximity switch (not shown) can be used instead of the limit valve 116.
  • the proximity switch can be in a normally open condition and can be closed when the jaw 41 is in an open condition.
  • electrical current can be supplied to cut-off switches instead of dump valves.
  • the cut-off switches can be arranged to interrupt electrical power supply to solenoids that activate pilot pressure supply to main control valves (not shown) operatively associated with the stick piston and cylinder assemblies 20, 20. Accordingly, operation of the stick 16 is interrupted when the jaw 41 is in an open condition.
  • the proximity switch can be arranged to disable release of the travel brake (not shown) by means of a cut-off switch when the proximity switch is closed.
  • the float valve 112 is caused to be switched to the position shown in Figure 5 A in response to the controller (not shown) being operated to close the jaw 41.
  • the controller When the controller is operated to close the jaw 41, the pilot pressure line 132 is pressurized to cause the float valve 112 to switch. It will be appreciated that the line 132 is operatively connected to the controller at 133.
  • a rod-end chamber 42.4 and a head-end chamber 42.5 of each jaw piston and cylinder assembly 42 are operatively connected in flow communication with one another, as indicated at 150 to permit pressure in the jaw piston and cylinder assemblies 42, 42 to be relieved.
  • the jaw 41 is then permitted to close under the influence of gravity thereby causing the piston rods 42.3, 42.3 of the jaw piston and cylinder assemblies 42, 42 to extend, as indicated by arrows J, J in Figure 5A of the drawings. Accordingly, the jaw 41 closes due to the shovel 40 gravitating toward the dozer 28.
  • the main control valve (not shown) for operation of the jaw piston and cylinder assemblies 42, 42 to close the jaw 41 is switched off when the controller is operated to close the jaw 41. This can be achieved by interrupting a pilot pressure line to the main control valve, as indicated at 137, when the controller (not shown) is operated to close the jaw 41.
  • the suction valve 114 is provided to compensate for increased total volume in the rod-end chambers 42.4, 42.4 and the head-end chambers 42.5, 42.5 due to less of the piston rods 42.3, 42.3 being in the rod-end chambers 42.4, 42.4 as the piston rods 42.3, 42.3 extend in response to the shovel arrangement 40 gravitating toward the dozer 28.
  • hydraulic fluid is then sucked from a back-to-tank system 152, as indicated by arrow G in Figure 5 of the drawings, through the suction valve 114.
  • the float valve 112 is caused to switch to the position as shown in Figure 5B of the drawings when the jaw 41 is in a closed condition corresponding to the shovel arrangement being at an end of a range of travel relative to the dozer.
  • the limit valve 116 is caused to switch. This causes the line 122 to be depressurized thereby to cause the line 126 to be depressurized. Depressurization of the line 126 causes the sensing valve 123 to switch to the position as shown in Figure 5B. In this position, the line 132 is caused to depressurize thereby to cause the float valve 112 to switch into the position shown in Figure 5B of the drawings.
  • a pilot pressure line from the controller (not shown) to the main control valve (not shown) of the jaw piston and cylinder assemblies 42, 42 is opened, as indicated at 135, to permit the jaw 41 to be held in a closed condition under pressure. It will be appreciated that opening the line from the controller to the main control valve when the jaw 41 is in a closed condition enables the main control valve to cause the jaw piston and cylinder assemblies 42, 42 to be pressurized through lines 140 thereby to retain the jaw 41 in a closed condition under pressure.
  • a hydraulic circuit in accordance with one embodiment of another aspect of the invention is generally indicated by reference numeral 210.
  • the hydraulic circuit 210 is arranged to regulate extension and retraction of the dozer 28 of the earth working head 26 of the part of the earth working assembly 110 shown in Figures 1 and 2 of the drawings.
  • the hydraulic circuit 210 corresponds with the earth working head 26 being in an extended condition, as indicated in Figure 2 of the drawings.
  • the hydraulic circuit 210 corresponds with the earth working head 26 being in a fully retracted condition, as indicated in Figure 1 of the drawings.
  • the hydraulic circuit 210 is provided with a limit valve 212, a check valve 214, a dump valve 216 and a float valve 218.
  • the float valve 212 is typically mounted relative to the dozer 28 such that when the dozer is retracted into a position at an end of a range of travel corresponding with the fully retracted position, the limit valve 212 is switched from the condition as shown in Figure 7 to the condition as shown in Figure 6. Pilot pressure is then tapped through the line 220 from a main pilot pressure circuit (not shown). The pilot pressure causes the float valve 212 to be switched into the condition as shown in Figure 6 from the condition as shown in Figure 7 through pressure in the lines 222.
  • each dozer piston and cylinder assembly 32, 32 are operatively connected to one another as indicated at 224 thereby to relieve pressure in the dozer piston and cylinder assemblies 32, 32 to permit the dozer to gravitate relative to the arm component 16.
  • pilot pressure switches the dump valve 216 from the condition shown in Figure 7 to the condition shown in Figure 6. Pilot pressure feed through the line 226 to main control valve spools (not shown) operatively connected to the dozer piston and cylinder assemblies 32, 32 is then dumped as indicated at 228 to cause the spools to return to neutral positions. The earth working head 26 then typically gravitates relative to the arm component 16 to cause the stops 38.1, 38.2 to "float" relative to each other.
  • the stick 16 can be retracted in the direction of arrow H in Figure 1 of the drawings while alleviating strain in the stick 16, the dozer piston and cylinder assemblies 32, 32, the dozer 28 and associated bushes and pins (not shown), when the stick 16 is retracted while the dozer is in the fully retracted condition. Accordingly, when the stick 16 is retracted while the stops 38.1, 38.2 are adjacent each other, the limit valve 212 and the float valve 218 is switched to inhibit strain in the associated components already mentioned.
  • an electrical proximity switch (not shown) can be used instead of the limit valve 212.
  • the proximity switch can be in a normally open condition and can be closed when the stops 38.1, 38.2 are adjacent each other.
  • a solenoid associated with a float valve similar to the float valve 218 can be activated to cause the float valve to be switched into a condition similar to that shown in Figure 6 of the drawings in which the rod-end 32.1 and the head-end 32.2 of each dozer piston and cylinder assembly 32, 32 are operatively connected to one another as described above.
  • the proximity switch can cause the main control valve spools (not shown) operatively connected to the dozer piston and cylinder assemblies 32, 32 to return to neutral positions in a manner similar to that described above.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Mining & Mineral Resources (AREA)
  • Civil Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Operation Control Of Excavators (AREA)

Abstract

Hydraulic control systems for an earth working assembly (10), is provided. The earth working assembly (10) includes at least two components (28, 40) mounted for displacement relative to each other within a range of travel DD. The earth working assembly (10) further includes at least one hydraulically operable piston and cylinder assembly (42) operatively connected between the at least two components (28, 4)0 and arranged to cause displacement of the components (28, 40) within the range of travel DD. Switch means arranged selectively to be switched to cause pressure in the at least one hydraulically operable piston and cylinder assembly (42) to be relieved thereby to permit one of the at least two components (28, 40) to gravitate relative to the other of the at least two components is provided.

Description

Title:
Control systems for earth working equipment.
Field:
This invention relates to earth working equipment. In particular, the invention relates to control systems for controlling an earth working assembly of earth working equipment.
Background:
Earth working assemblies, such as, for example, shovel arrangements carried on remote ends of arms, and the like, are often used to work the earth. Such assemblies are often mounted on vehicles, such as, for example, bull-dozers, and the like.
When such earth working assemblies are used to work the earth, they are often subjected to relatively large amounts of strain. This often leads to failure of some components of the earth working assemblies. Typically, these components have to be replaced, or repaired, to enable the earth working assemblies to continue working.
It is an object of the invention to provide control systems for an earth working assembly, which control systems are arranged at least to alleviate strain in some of the components of the earth working assembly.
Summary:
According to one aspect of the invention, there is provided an earth working assembly including at least two components mounted for displacement relative to each other within a range of travel, at least one hydraulically operable piston and cylinder assembly operatively connected between the at least two components and arranged to cause displacement of the components within the range of travel and switch means arranged selectively to be switched to cause pressure in the at least one hydraulically operable piston and cylinder assembly to be relieved thereby to permit one of the at least two components to gravitate relative to the other of the at least two components.
One of the at least two components may be a shovel arrangement mounted for angular displacement relative to the other of the at least two components.
The at least one hydraulically operable piston and cylinder assembly may be arranged selectively to be pressurized so as to cause the shovel arrangement to displace angularly away from the other of the at least two components. The switch means may then be arranged to cause pressure in the at least one hydraulically operable piston and cylinder assembly to be relieved so as to permit the shovel arrangement to gravitate angularly toward the other of the at least two components.
The switch means may be arranged to connect a rod-end chamber and a head-end chamber of the at least one hydraulically operable piston and cylinder assembly together in flow communication so as to permit pressure in the at least one hydraulically operable piston and cylinder assembly to be relieved by enabling fluid flow between the rod-end chamber and the head-end chamber.
The switch means may be arranged to permit fluid flow from a fluid source to the hydraulically operable piston and cylinder assembly so as to compensate for volume variation in the rod-end chamber as the shovel arrangement gravitates angularly toward the other of the at least two components.
The earth working assembly may include a suction valve through which the switch means is arranged to permit fluid flow from the fluid source to the hydraulically operable piston and cylinder assembly.
The switch means may be arranged to permit the at least one hydraulically operable piston and cylinder assembly to be pressurized when the shovel arrangement is at an end of the range of travel after having gravitated toward the other of the at least two components thereby to hold the shovel arrangement at that end of the range of travel under pressure.
The earth working assembly may include two hydraulically operable piston and cylinder assemblies operatively connected between the shovel arrangement and the other of the at least two components. Both of the hydraulically operable piston and cylinder assemblies may be arranged to be pressurized so as to cause the shovel arrangement to displace angularly away from the other of the at least two components. The switch means may then be arranged to cause pressure in both hydraulically operable piston and cylinder assemblies to be relieved so as to permit the shovel arrangement to gravitate angularly toward the other of the at least two components.
The switch means may be arranged to connect a rod-end chamber and a head-end chamber of both piston and cylinder assemblies together in flow communication so as to permit pressure in both hydraulically operable piston and cylinder assemblies to be relieved by enabling fluid flow between the rod-end chambers and the head-end chambers.
The switch means may be arranged to permit fluid flow from a fluid source to the hydraulically operable piston and cylinder assemblies so as to compensate for volume variation in the rod-end chambers as the shovel arrangement gravitates angularly toward the other of the at least two components.
The earth working assembly may include a suction valve through which the switch means is arranged to permit fluid flow from the fluid source to the hydraulically operable piston and cylinder assemblies.
The switch means may be arranged to permit both hydraulically operable piston and cylinder assemblies to be pressurized when the shovel arrangement is at an end of the range of travel after having gravitated toward the other of the at least two components thereby to hold the shovel arrangement at that end of the range of travel under pressure. The earth working assembly may include a main control valve for controlling supply pressure to the, or each, hydraulically operable piston and cylinder assembly. The switch means may then be arranged to cause pressure supply from the main control valve to the, or each, hydraulically operable piston and cylinder assembly to be interrupted when the shovel arrangement gravitates angularly toward the other of the at least two components.
The other of the at least two components may be a dozer.
The switch means may include a hydraulic valve. Instead, the switch means may include an electrical switch.
One of the at least two components may be a dozer arranged to be angularly displaceable relative to the other of the at least two components.
The at least one hydraulically operable piston and cylinder assembly may be arranged to be pressurized so as to cause the dozer selectively to displace angularly toward and away from the other of the at least two components. The switch means may then be arranged to be switched when the dozer is at a position at one end of the range of travel thereby to cause pressure in the at least one hydraulically operable piston and cylinder assembly to be relieved so as to permit the dozer to gravitate relative to the other of the at least two components.
The switch means may be arranged to connect a rod-end chamber and a head-end chamber of the at least one hydraulically operable piston and cylinder assembly together in flow communication thereby to permit pressure in the at least one hydraulically operable piston and cylinder assembly to be relieved.
The earth working assembly may include two hydraulically operable piston and cylinder assemblies operatively connected between the dozer and the other of the at least two components. Both hydraulically operable piston and cylinder assemblies may be arranged to be pressurized so as to cause the dozer selectively to displace angularly toward and away from the other of the at least two components. The switch means may then be arranged to be switched when the dozer is at a position at one end of the range of travel thereby to cause pressure in both hydraulically operable piston and cylinder assemblies to be relieved so as to permit the dozer to gravitate relative to the other of the at least two components.
The switch means may be arranged to connect a rod-end chamber and a head-end chamber of both piston and cylinder assemblies together in flow communication as to permit pressure in both hydraulically operable piston and cylinder assemblies to be relieved.
The switch means may be operatively mounted relative to the dozer and the other of the at least two components so as to be switched in response to the dozer being displaced toward the other of the at least two components to the position at the one end of the range of travel.
The earth working assembly may include a main control valve for controlling supply pressure to the, or each, piston and cylinder assembly. The switch means may then be operatively associated with the main control valve so as to cause the main control valve to interrupt pressure supply to the, or each, piston and cylinder assembly in response to the at least two components being displaced to the position at the one end of the range of travel.
The other of the at least two components may be an arm.
The switch means may include a hydraulic valve. Instead, the switch means may include an electrical switch. According to another aspect of the invention, there is provided an earth working assembly including an earth working head defining at least two components mounted for displacement relative to each other within a range of travel, an arm on which the earth working head is mounted for displacement relative to the arm, a body on which the arm is mounted for displacement relative to the body, at least one hydraulically operable piston and cylinder assembly operatively connected between the at least two components and arranged to control displacement of the components relative to each other, at least one hydraulically operable piston and cylinder assembly operatively connected between the earth working head and the arm and arranged to control displacement of the earth working head relative to the arm, at least one hydraulically operable piston and cylinder assembly operatively connected between the arm and the body and arranged to control displacement of the arm relative to the body and switch means arranged to be switched when the at least two components are displaced relative to each other to a position at one end of the range of travel, the switch means being arranged to interrupt a pressure supply to at least one of the at least one hydraulically operable piston and cylinder assembly operatively connected between the arm and the earth working head and the at least one hydraulically operable piston and cylinder assembly operatively connected between the arm and the body, in response to the at least two components being displaced relative to each other away from the position at the one end of the range of travel.
One of the at least two components defined by the earth working head may be a shovel arrangement mounted for angular displacement relative to the other of the at least two components.
The one end of the range of travel may correspond with a closed condition of the earth working head in which the shovel arrangement is angularly positioned immediately adjacent the other of the at least two components.
The earth working assembly may include two hydraulically operable piston and cylinder assemblies operatively connected between the arm and the body. Both hydraulically operable piston and cylinder assemblies may be arranged to control displacement of the arm relative to the body.
The earth working assembly may include a main control valve for controlling supply pressure to the, or each, hydraulically operable piston and cylinder assembly operatively connected between the arm and the body. The switch means may then be operatively associated with the main control valve so as to cause the main control valve to interrupt pressure supply to the, or each, hydraulically operable piston and cylinder assembly operatively connected between the arm and the body in response to the shovel arrangement being angularly displaced away from the position at the one end of the range of travel.
The other of the at least two components of the earth working head may be in the form of a dozer.
The body may be in the form of a boom.
The earth working assembly may further include a travel brake. The switch means may be arranged to inhibit release of the travel brake in response to the at least two components being displaced away from the position at the one end of the range of travel.
The earth working assembly may include two hydraulically operable piston and cylinder assemblies operatively connected between the at least two components defined by the working head, both hydraulically operable piston and cylinder assemblies being arranged to control displacement of the at least two components relative to each other.
The switch means may include a hydraulic valve. Instead, the switch means may include an electrical switch.
Description of preferred embodiments: Embodiments of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which:
Figure 1 shows a schematic side view of part of an earth working assembly, a dozer of an earth working head of the earth working assembly being shown in a fully retracted condition;
Figure 2 shows a schematic side view of the part of the earth working assembly shown Figure 1, the dozer of the earth working head of the earth working assembly being shown in an extended condition;
Figure 3 shows, at an enlarge scale, a schematic side view of the earth working head of the earth working assembly shown in Figures 1 and 2, a jaw of the earth working head being shown in an open condition;
Figure 4 shows a schematic hydraulic diagram of a hydraulic circuit in accordance with one embodiment of the invention, the hydraulic circuit being arranged to regulate opening and closing of the jaw shown in Figure 3, the hydraulic circuit corresponding to the jaw being in an open condition;
Figure 5 A shows a schematic hydraulic diagram of the hydraulic circuit shown in Figure 4, the hydraulic circuit corresponding to the jaw being closed;
Figure 5B shows a schematic hydraulic diagram of the hydraulic circuit shown in Figure 4, the hydraulic circuit corresponding to the jaw being in a fully closed condition;
Figure 6 shows a schematic hydraulic diagram of a hydraulic circuit in accordance with one embodiment of the invention, the hydraulic circuit being arranged to regulate the extension and retraction of the earth working head of the earth working assembly shown in Figures 1 and 2 of the drawings, the hydraulic circuit corresponding to the earth working head being in an extended condition; and Figure 7 shows a schematic hydraulic diagram of the hydraulic circuit shown in Figure 6, the hydraulic circuit corresponding to the earth working head being in a fully retracted condition.
Referring to Figures 1 and 2 of the drawings, part of an earth working assembly is generally indicated by reference numeral 10. The part of the earth working assembly 10 can form part of an earth working vehicle, such as, for example, a bull dozer, a wheel dozer, or the like.
The part of the working assembly 10 includes a body, or boom 12 and a pivotal connection 14 secured relative to a super structure (not shown) of the rest of the earth working assembly. The boom 12 is pivotally mounted on the super structure to be angularly displaceable relative to the super structure as indicated by arrows BB. To this end, a pair of boom piston and cylinder assemblies 19, 19 are provided, only one of which is shown in Figures 1 and 2 of the drawings.
An arm component, or stick 16, is pivotally connected to the boom 12 by means of a pivotal connection 18. The stick 16 is angularly displaceable relative to the boom 12 about the pivotal connection 18 as indicated by arrows AA. Angular displacement of the stick 16 relative to the boom 12 is controlled by a pair of stick piston and cylinder assemblies 20, 20, only one of which is shown in Figures 1 and 2 of the drawings. One end 20.1 of the stick piston and cylinder assembly 20 is pivotally connected to the boom 12 by means of a pivotal connection 22. An opposed end 20.2 of the stick piston and cylinder assembly 20 is pivotally connected to the stick 16 by means of a pivotal connection 24.
The part of the earth working assembly 10 further includes an earth working head, or bucket, generally indicated by reference numeral 26. The earth working head 26 defines a component in the form of a dozer 28. The dozer 28 is connected to the stick 16 by means of a pivotal connection 30 to be angularly displaceable relative to the stick 16 about the pivotal connection 30 as indicated by arrows CC. A pair of bucket, or dozer, piston and cylinder assemblies 32, 32 only one of which is shown in Figures 1 and 2 of the drawings, is provided to control angular displacement of the dozer 28 about the pivotal connection 30. One end 32.1 of the bucket piston and cylinder assembly 32 is pivotally connected to the dozer 28 by means of a pivotal connection 34. An opposed end 32.2 of the bucket piston and cylinder assembly 32 is pivotally connected to the boom 12 by means of a pivotal connection 36.
It will be appreciated that the bucket piston and cylinder assemblies 32, 32 control angular displacement of the dozer 28 within a range of travel between a fully retracted position, as indicated in Figure 1 of the drawings, and an extended position, as indicated in Figure 2 of the drawings. A stop arrangement, generally indicated at 38, stops the dozer 28 relative to the stick 16 when in a fully retracted position. The stop arrangement 38 defines a stop 38.1 on the dozer 28 and an associated stop 38.2 on the stick 16.
Referring now to Figure 3 of the drawings, in which like reference numerals have been used to designate similar parts, unless otherwise stated, the earth working head 26 defines another component in the form of a shovel arrangement 40. The shovel arrangement 40 and the dozer 28 together define a jaw generally indicated by reference numeral 41. The shovel arrangement 40 is pivotally connected to the dozer 28 by means of a pivotal connection 42 to be angularly displaceable within a range of travel about the pivotal connection 42 as indicated by arrows DD. To control angular displacement of the shovel arrangement 40, a pair of jaw piston and cylinder assemblies 42, 42 is provided, only one of which is shown in Figure 3. One end 42.1 of the jaw piston and cylinder assembly 42 is pivotally connected to the shovel arrangement 40 at 44. An opposed end 42.2 of the jaw piston and cylinder assembly 42 is pivotally connected to the dozer 28 at 46. It will be appreciated that when a piston rod 42.3 of each jaw piston and cylinder assembly 42, 42 is extended, as indicated by arrow E, the jaw 41 is closed, and when the piston rod 42.3 of each jaw piston and cylinder assembly 42, 42 is retracted, as indicated by arrow F, the jaw 41 is opened. Referring now to Figures 4, 5 A and 5B of the drawings, a hydraulic circuit of the earth working assembly, in accordance with one embodiment of the invention, is generally indicated by reference numeral 110. In Figures 4, 5 A and 5B like reference numerals have been used to designate similar parts, unless otherwise stated.
It has been found that when an operator of the earth working assembly works the earth while the jaw 41 is not in a fully closed condition, the jaw 41 and the jaw piston and cylinder assemblies 42, 42 are subjected to large amounts of strain. The hydraulic circuit 110 is arranged to inhibit the earth working assembly from being operated to work the earth when the jaw 41 is not in a closed condition thereby to inhibit such strain on the jaw 41 and the jaw piston and cylinder assemblies 42, 42.
The hydraulic circuit 110 includes a float valve 112, a suction valve 114, a limit valve 116, a manifold 118, dump valves 120, 120 and a sensing valve 123. The hydraulic circuit 110 is arranged to prevent the stick piston and cylinder assemblies 20, 20, and a travel brake assembly (not shown) from being operated unless the jaw 41 is in a closed condition, as indicated in Figure 1 of the drawings. This will now be described.
The limit valve 116 can be mounted relative to one of the jaw piston and cylinder assemblies 42, 42. The limit valve 116 is typically arranged to be switched, as indicated in Figure 5B of the drawings, when the jaw 41 is in a closed condition. This can typically be achieved by providing an appropriate arm, or bracket 50 mounted relative to the piston rod 42.3 of the one of the jaw piston and cylinder assemblies 42 such that when the piston rod 42.3 of the one of the jaw piston and cylinder assemblies 42 is at an extended position in which the jaw 41 is closed, the arm 50 causes the limit valve 116 to switch. When the limit valve 116 is switched, a pilot pressure line 122 is caused to be depressurized, as indicated at 124. The pilot pressure line 122 is operatively connected to pilot pressure lines 126, 128, 130 through the manifold 118. Accordingly, when the pilot pressure line 122 is depressurized, the pilot pressure lines 126, 128, 130 are depressurized as well. The dump valves 120, 120 and the sensing valve 123 are operatively connected to main pilot pressure lines 134, 136, 132 respectively. The main pilot pressure line 132 is operatively connected to the float valve 112. The main pilot pressure line 134 is operatively connected to a spool (not shown) in a main control valve (not shown) operatively connected in a hydraulic line arranged to enable the stick piston and cylinder assemblies 20, 20 to be pressurized. The main pilot pressure line 136 is operatively connected to a travel brake assembly (not shown) to enable the travel brake assembly to be released. When the pilot pressure lines 126, 128, 130 are depressurized as indicated in Figure 5B of the drawings, the main pilot pressure lines 134, 136 are operable to permit operation of the stick piston and cylinder assemblies 20, 20 and release of the travel brake assembly (not shown). Accordingly, when the jaw 41 is closed, angular displacement of the stick 16 and release of the travel brake assembly (not shown) is enabled.
Referring now to Figure 4 of the drawings, when the jaw piston and cylinder assemblies 42 have been operated to cause the jaw 41 to be open, the arm 50 is displaced away from the limit valve 116. This causes the limit valve 116 to be switched so as to cause the pilot pressure line 122 to be pressurized. Typically, pressure to the line 122 is provided by tapping the pressure from a main pilot pressure circuit (not shown) of the earth working assembly, as indicated by line 121. The pilot pressure lines 126, 128, 130 are pressurized in response to pressurization of the pilot pressure line 122 to cause the dump valves 120, 120 and the sensing valve 123 to be switched. In response to the dump valves 120, 120 being switched, the main pilot pressure lines 134, 136 are depressurized thereby to prevent operation of the stick piston and cylinder assemblies 20, 20 and the travel brake assembly (not shown). In this way, angular displacement of the stick 16 and release of the travel brake assembly (not shown) is disabled in response to the jaw 41 being in an open condition. Accordingly, an operator of the earth working assembly can only use the assembly to dig if the jaw 41 is in a closed condition.
In accordance with another embodiment of this aspect of the invention, an electrical proximity switch (not shown) can be used instead of the limit valve 116. In such an embodiment, the proximity switch can be in a normally open condition and can be closed when the jaw 41 is in an open condition. When the proximity switch is closed, electrical current can be supplied to cut-off switches instead of dump valves. The cut-off switches can be arranged to interrupt electrical power supply to solenoids that activate pilot pressure supply to main control valves (not shown) operatively associated with the stick piston and cylinder assemblies 20, 20. Accordingly, operation of the stick 16 is interrupted when the jaw 41 is in an open condition. In addition, the proximity switch can be arranged to disable release of the travel brake (not shown) by means of a cut-off switch when the proximity switch is closed.
Another aspect of the invention will now be described with reference to Figures 4 and 5 A of the drawings. It has been found that when the jaw 41 is closed using pressure in the jaw piston and cylinder assemblies 42, 42, the jaw is often slammed closed. This often leads to large amounts of strain caused by impact stresses as the jaw 41 is slammed closed. This aspect of the invention is arranged at least to alleviate such strain when the jaw 41 is closed.
To open the jaw 41 the piston rods 42.3, 42.3 of the jaw piston and cylinder assemblies 42, 42 are caused to retract, as indicated by arrows I, I in Figure 4 of the drawings. Referring to Figure 4 of the drawings, this is typically achieved by pressurizing the lines 138 through the float valve 112. Pressurizing the lines 138 is typically achieved through a main control valve (not shown) down-stream of the float valve 112. The main control valve is typically controlled by a manually operable controller (not shown).
To close the jaw 41, in accordance with one embodiment of this aspect of the invention, the float valve 112 is caused to be switched to the position shown in Figure 5 A in response to the controller (not shown) being operated to close the jaw 41. When the controller is operated to close the jaw 41, the pilot pressure line 132 is pressurized to cause the float valve 112 to switch. It will be appreciated that the line 132 is operatively connected to the controller at 133. In response to the float valve 112 being switched in this fashion, a rod-end chamber 42.4 and a head-end chamber 42.5 of each jaw piston and cylinder assembly 42 are operatively connected in flow communication with one another, as indicated at 150 to permit pressure in the jaw piston and cylinder assemblies 42, 42 to be relieved. The jaw 41 is then permitted to close under the influence of gravity thereby causing the piston rods 42.3, 42.3 of the jaw piston and cylinder assemblies 42, 42 to extend, as indicated by arrows J, J in Figure 5A of the drawings. Accordingly, the jaw 41 closes due to the shovel 40 gravitating toward the dozer 28. Advantageously, the main control valve (not shown) for operation of the jaw piston and cylinder assemblies 42, 42 to close the jaw 41 is switched off when the controller is operated to close the jaw 41. This can be achieved by interrupting a pilot pressure line to the main control valve, as indicated at 137, when the controller (not shown) is operated to close the jaw 41.
It will be appreciated that in this way, main hydraulic pump pressure for pressurizing lines 140 to cause the piston rods 42.3, 42.3 to extend, thereby to close the jaw 41, is obviated. It will further be appreciated that flow of hydraulic fluid from the rod-end chambers 42.4 to the head-end chambers 42.5, 42.5 through the lines 138, 140 retards the shovel arrangement 40 as it drops toward the dozer. In this way, slamming of the jaw closed under pressure of the jaw piston and cylinder assemblies 42, 42 can at least be alleviated. Accordingly, the jaw 41 is opened under hydraulic pressure and closed under gravity.
The suction valve 114 is provided to compensate for increased total volume in the rod-end chambers 42.4, 42.4 and the head-end chambers 42.5, 42.5 due to less of the piston rods 42.3, 42.3 being in the rod-end chambers 42.4, 42.4 as the piston rods 42.3, 42.3 extend in response to the shovel arrangement 40 gravitating toward the dozer 28. Typically, hydraulic fluid is then sucked from a back-to-tank system 152, as indicated by arrow G in Figure 5 of the drawings, through the suction valve 114.
Referring now to Figure 5B of the drawings, the float valve 112 is caused to switch to the position as shown in Figure 5B of the drawings when the jaw 41 is in a closed condition corresponding to the shovel arrangement being at an end of a range of travel relative to the dozer. When the jaw 41 is in closed condition, the limit valve 116 is caused to switch. This causes the line 122 to be depressurized thereby to cause the line 126 to be depressurized. Depressurization of the line 126 causes the sensing valve 123 to switch to the position as shown in Figure 5B. In this position, the line 132 is caused to depressurize thereby to cause the float valve 112 to switch into the position shown in Figure 5B of the drawings. At the same time, a pilot pressure line from the controller (not shown) to the main control valve (not shown) of the jaw piston and cylinder assemblies 42, 42 is opened, as indicated at 135, to permit the jaw 41 to be held in a closed condition under pressure. It will be appreciated that opening the line from the controller to the main control valve when the jaw 41 is in a closed condition enables the main control valve to cause the jaw piston and cylinder assemblies 42, 42 to be pressurized through lines 140 thereby to retain the jaw 41 in a closed condition under pressure.
Referring now to Figures 6 and 7 of the drawings, in which like reference numerals have been used to designate similar parts, unless otherwise stated, a hydraulic circuit in accordance with one embodiment of another aspect of the invention, is generally indicated by reference numeral 210. The hydraulic circuit 210 is arranged to regulate extension and retraction of the dozer 28 of the earth working head 26 of the part of the earth working assembly 110 shown in Figures 1 and 2 of the drawings. In Figure 6, the hydraulic circuit 210 corresponds with the earth working head 26 being in an extended condition, as indicated in Figure 2 of the drawings. In Figure 7 the hydraulic circuit 210 corresponds with the earth working head 26 being in a fully retracted condition, as indicated in Figure 1 of the drawings.
As can best be described with reference to Figure 1 of the drawings, it has been found that when the dozer 28 is in a fully retracted position, in which the stops 38.1, 38.2 abut, and the stick 16 is then retracted as indicated by arrow H, the stick 16, the dozer piston and cylinder assemblies 32, 32, the dozer 28 and associated bushes and pins (not shown), can be subjected to great amounts of strain due to the stick 16 being retracted against pressure in the dozer piston and cylinder assemblies 32, 32. Returning now to Figures 6 and 7 of the drawings, the hydraulic circuit 210 is arranged at least to alleviate such strain, as will now be described.
The hydraulic circuit 210 is provided with a limit valve 212, a check valve 214, a dump valve 216 and a float valve 218. The float valve 212 is typically mounted relative to the dozer 28 such that when the dozer is retracted into a position at an end of a range of travel corresponding with the fully retracted position, the limit valve 212 is switched from the condition as shown in Figure 7 to the condition as shown in Figure 6. Pilot pressure is then tapped through the line 220 from a main pilot pressure circuit (not shown). The pilot pressure causes the float valve 212 to be switched into the condition as shown in Figure 6 from the condition as shown in Figure 7 through pressure in the lines 222. In consequence, a rod-end 32.1 and a head-end 32.2 of each dozer piston and cylinder assembly 32, 32 are operatively connected to one another as indicated at 224 thereby to relieve pressure in the dozer piston and cylinder assemblies 32, 32 to permit the dozer to gravitate relative to the arm component 16.
The pilot pressure switches the dump valve 216 from the condition shown in Figure 7 to the condition shown in Figure 6. Pilot pressure feed through the line 226 to main control valve spools (not shown) operatively connected to the dozer piston and cylinder assemblies 32, 32 is then dumped as indicated at 228 to cause the spools to return to neutral positions. The earth working head 26 then typically gravitates relative to the arm component 16 to cause the stops 38.1, 38.2 to "float" relative to each other. In this way, the stick 16 can be retracted in the direction of arrow H in Figure 1 of the drawings while alleviating strain in the stick 16, the dozer piston and cylinder assemblies 32, 32, the dozer 28 and associated bushes and pins (not shown), when the stick 16 is retracted while the dozer is in the fully retracted condition. Accordingly, when the stick 16 is retracted while the stops 38.1, 38.2 are adjacent each other, the limit valve 212 and the float valve 218 is switched to inhibit strain in the associated components already mentioned. In accordance with another embodiment of this aspect of the invention, an electrical proximity switch (not shown) can be used instead of the limit valve 212. In such an embodiment, the proximity switch can be in a normally open condition and can be closed when the stops 38.1, 38.2 are adjacent each other. When the proximity switch is closed, a solenoid associated with a float valve similar to the float valve 218 can be activated to cause the float valve to be switched into a condition similar to that shown in Figure 6 of the drawings in which the rod-end 32.1 and the head-end 32.2 of each dozer piston and cylinder assembly 32, 32 are operatively connected to one another as described above. At generally the same time, the proximity switch can cause the main control valve spools (not shown) operatively connected to the dozer piston and cylinder assemblies 32, 32 to return to neutral positions in a manner similar to that described above.

Claims

Claims:
1. An earth working assembly including: at least two components mounted for displacement relative to each other within a range of travel; at least one hydraulically operable piston and cylinder assembly operatively connected between the at least two components and arranged to cause displacement of the components within the range of travel; and switch means arranged selectively to be switched to cause pressure in the at least one hydraulically operable piston and cylinder assembly to be relieved thereby to permit one of the at least two components to gravitate relative to the other of the at least two components.
2. The earth working assembly as claimed in claim 1, in which one of the at least two components is a shovel arrangement mounted for angular displacement relative to the other of the at least two components.
3. The earth working assembly as claimed in claim 2, in which the at least one hydraulically operable piston and cylinder assembly is arranged selectively to be pressurized so as to cause the shovel arrangement to displace angularly away from the other of the at least two components and the switch means is arranged to cause pressure in the at least one hydraulically operable piston and cylinder assembly to be relieved so as to permit the shovel arrangement to gravitate angularly toward the other of the at least two components.
4. The earth working assembly as claimed in claim 3, in which the switch means is arranged to connect a rod-end chamber and a head-end chamber of the at least one hydraulically operable piston and cylinder assembly together in flow communication so as to permit pressure in the at least one hydraulically operable piston and cylinder assembly to be relieved by enabling fluid flow between the rod-end chamber and the head-end chamber.
5. The earth working assembly as claimed in claim 4, in which the switch means is arranged to permit fluid flow from a fluid source to the hydraulically operable piston and cylinder assembly so as to compensate for volume variation in the rod-end chamber as the shovel arrangement gravitates angularly toward the other of the at least two components.
6. The earth working assembly as claimed in claim 5, which includes a suction valve through which the switch means is arranged to permit fluid flow from the fluid source to the hydraulically operable piston and cylinder assembly.
7. The earth working assembly as claimed in any one of claims 3 to 6 inclusive, in which the switch means is arranged to permit the at least one hydraulically operable piston and cylinder assembly to be pressurized when the shovel arrangement is at an end of the range of travel after having gravitated toward the other of the at least two components thereby to hold the shovel arrangement at that end of the range of travel under pressure.
8. The earth working assembly as claimed in claim 3, which includes two hydraulically operable piston and cylinder assemblies operatively connected between the shovel arrangement and the other of the at least two components, both of the hydraulically operable piston and cylinder assemblies being arranged to be pressurized so as to cause the shovel arrangement to displace angularly away from the other of the at least two components, the switch means being arranged to cause pressure in both hydraulically operable piston and cylinder assemblies to be relieved so as to permit the shovel arrangement to gravitate angularly toward the other of the at least two components.
9. The earth working assembly as claimed in claim 8, in which the switch means is arranged to connect a rod-end chamber and a head-end chamber of both piston and cylinder assemblies together in flow communication so as to permit pressure in both hydraulically operable piston and cylinder assemblies to be relieved by enabling fluid flow between the rod-end chambers and the head-end chambers.
10. The earth working assembly as claimed in claim 9, in which the switch means is arranged to permit fluid flow from a fluid source to the hydraulically operable piston and cylinder assemblies so as to compensate for volume variation in the rod-end chambers as the shovel arrangement gravitates angularly toward the other of the at least two components.
11. The earth working assembly as claimed in claim 10, which includes a suction valve through which the switch means is arranged to permit fluid flow from the fluid source to the hydraulically operable piston and cylinder assemblies.
12. The earth working assembly as claimed in any one of claims 8 to 11 inclusive, in which the switch means is arranged to permit both hydraulically operable piston and cylinder assemblies to be pressurized when the shovel arrangement is at an end of the range of travel after having gravitated toward the other of the at least two components thereby to hold the shovel arrangement at that end of the range of travel under pressure.
13. The earth working assembly as claimed in any one of claims 3 to 12 inclusive, which includes a main control valve for controlling supply pressure to the, or each, hydraulically operable piston and cylinder assembly, the switch means being arranged to cause pressure supply from the main control valve to the, or each, hydraulically operable piston and cylinder assembly to be interrupted when the shovel arrangement gravitates angularly toward the other of the at least two components.
14. The earth working assembly as claimed in any one of claims 2 to 13 inclusive, in which the other of the at least two components is a dozer.
15. The earth working assembly as claimed in any one of the preceding claims, in which the switch means includes a hydraulic valve.
16. The earth working assembly as claimed in any one of claims 1 to 14 inclusive, in which the switch means includes an electrical switch.
17. The earth working assembly as claimed in claim 1, in which one of the at least two components is a dozer arranged to be angularly displaceable relative to the other of the at least two components.
18. The earth working assembly as claimed in claim 17, in which the at least one hydraulically operable piston and cylinder assembly is arranged to be pressurized so as to cause the dozer selectively to displace angularly toward and away from the other of the at least two components, the switch means being arranged to be switched when the dozer is at a position at one end of the range of travel thereby to cause pressure in the at least one hydraulically operable piston and cylinder assembly to be relieved so as to permit the dozer to gravitate relative to the other of the at least two components.
19. The earth working assembly as claimed in claim 18, in which the switch means is arranged to connect a rod-end chamber and a head-end chamber of the at least one hydraulically operable piston and cylinder assembly together in flow communication so as to permit pressure in the at least one hydraulically operable piston and cylinder assembly to be relieved.
20. The earth working assembly as claimed in claim 17, which includes two hydraulically operable piston and cylinder assemblies operatively connected between the dozer and the other of the at least two components, both hydraulically operable piston and cylinder assemblies being arranged to be pressurized so as to cause the dozer selectively to displace angularly toward and away from the other of the at least two components, the switch means being arranged to be switched when the dozer is at a position at one end of the range of travel thereby to cause pressure in both hydraulically operable piston and cylinder assemblies to be relieved so as to permit the dozer to gravitate relative to the other of the at least two components.
21. The earth working assembly as claimed in claim 20, in which the switch means is arranged to connect a rod-end chamber and a head-end chamber of both piston and cylinder assemblies together in flow communication as to permit pressure in both hydraulically operable piston and cylinder assemblies to be relieved.
22. The earth working assembly as claimed in any one of claims 18 to 21 inclusive, in which the switch means is operatively mounted relative to the dozer and the other of the at least two components so as to be switched in response to the dozer being displaced toward the other of the at least two components to the position at the one end of the range of travel.
23. The earth working assembly as claimed in any one of claims 18 to 22 inclusive, which includes a main control valve for controlling supply pressure to the, or each, piston and cylinder assembly and the switch means is operatively associated with the main control valve so as to cause the main control valve to interrupt pressure supply to the, or each, piston and cylinder assembly in response to the at least two components being displaced to the position at the one end of the range of travel.
24. The earth working assembly as claimed in any one of claims 17 to 23 inclusive, in which the other of the at least two components is an arm.
25. The earth working assembly as claimed in any one of claims 17 to 24 inclusive, in which the switch means includes a hydraulic valve.
26. The earth working assembly as claimed in any one of claims 17 to 24 inclusive, in which the switch means includes an electrical switch.
27. An earth working assembly including: an earth working head defining at least two components mounted for displacement relative to each other within a range of travel; an arm on which the earth working head is mounted for displacement relative to the arm; a body on which the arm is mounted for displacement relative to the body; at least one hydraulically operable piston and cylinder assembly operatively connected between the at least two components and arranged to control displacement of the components relative to each other; at least one hydraulically operable piston and cylinder assembly operatively connected between the earth working head and the arm and arranged to control displacement of the earth working head relative to the arm; at least one hydraulically operable piston and cylinder assembly operatively connected between the arm and the body and arranged to control displacement of the arm relative to the body; and switch means arranged to be switched when the at least two components are displaced relative to each other to a position at one end of the range of travel, the switch means being arranged to interrupt a pressure supply to at least one of the at least one hydraulically operable piston and cylinder assembly operatively connected between the arm and the earth working head and the at least one hydraulically operable piston and cylinder assembly operatively connected between the arm and the body, in response to the at least two components being displaced relative to each other away from the position at the one end of the range of travel.
28. The earth working assembly as claimed in claim 27, in which one of the at least two components defined by the earth working head is a shovel arrangement mounted for angular displacement relative to the other of the at least two components.
29. The earth working assembly as claimed in claim 28, in which the one end of the range of travel corresponds with a closed condition of the earth working head in which the shovel arrangement is angularly positioned immediately adjacent the other of the at least two components.
30. The earth working assembly as claimed in any one of claims 27 to 29 inclusive, which includes two hydraulically operable piston and cylinder assemblies operatively connected between the arm and the body, both hydraulically operable piston and cylinder assemblies being arranged to control displacement of the arm relative to the body.
31. The earth working assembly as claimed in any one of claims 27 to 30, which includes a main control valve for controlling supply pressure to the, or each, hydraulically operable piston and cylinder assembly operatively connected between the arm and the body, the switch means being operatively associated with the main control valve so as to cause the main control valve to interrupt pressure supply to the, or each, hydraulically operable piston and cylinder assembly operatively connected between the arm and the body in response to the shovel arrangement being angularly displaced away from the position at the one end of the range of travel.
32. The earth working assembly as claimed in any one of claims 27 to 31 inclusive, in which the other of the at least two components of the earth working head is in the form of a dozer.
33. The earth working assembly as claimed in any one of claims 27 to 32, in which the body is in the form of a boom.
34. The earth working assembly as claimed in any one of claims 27 to 33 inclusive, which further includes a travel brake, the switch means being arranged to inhibit release of the travel brake in response to the at least two components being displaced away from the position at the one end of the range of travel.
35. The earth working assembly as claimed in any one of claims 27 to 34 inclusive, which includes two hydraulically operable piston and cylinder assemblies operatively connected between the at least two components defined by the working head, both hydraulically operable piston and cylinder assemblies being arranged to control displacement of the at least two components relative to each other.
36. The earth working assembly as claimed in any one of claims 27 to 35 inclusive, in which the switch means includes a hydraulic valve.
37. The earth working assembly as claimed in any one of claims 27 to 35 inclusive, in which the switch means includes an electrical switch.
38. An earth working assembly substantially as herein described and illustrated.
PCT/ZA2005/000122 2005-08-19 2005-08-19 Control systems for earth working equipment WO2007022546A1 (en)

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Application Number Priority Date Filing Date Title
PCT/ZA2005/000122 WO2007022546A1 (en) 2005-08-19 2005-08-19 Control systems for earth working equipment

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Application Number Priority Date Filing Date Title
PCT/ZA2005/000122 WO2007022546A1 (en) 2005-08-19 2005-08-19 Control systems for earth working equipment

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EP3564448A1 (en) * 2018-05-02 2019-11-06 Deere & Company Utility vehicle with front loader

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JPS63247430A (en) * 1987-03-30 1988-10-14 Sanyo Kiki Kk Oil-pressure device for dump control of loader
EP0378129A1 (en) * 1989-01-13 1990-07-18 Hitachi Construction Machinery Co., Ltd. Hydraulic system for boom cylinder of working apparatus
EP0389136A1 (en) * 1989-03-08 1990-09-26 Kabushiki Kaisha Kobe Seiko Sho Float circuit for boom of construction apparatus
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JPS63247430A (en) * 1987-03-30 1988-10-14 Sanyo Kiki Kk Oil-pressure device for dump control of loader
EP0378129A1 (en) * 1989-01-13 1990-07-18 Hitachi Construction Machinery Co., Ltd. Hydraulic system for boom cylinder of working apparatus
EP0389136A1 (en) * 1989-03-08 1990-09-26 Kabushiki Kaisha Kobe Seiko Sho Float circuit for boom of construction apparatus
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JPH10121510A (en) * 1996-10-21 1998-05-12 Hitachi Constr Mach Co Ltd Automatic stop controller for front working member
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Publication number Priority date Publication date Assignee Title
EP3564448A1 (en) * 2018-05-02 2019-11-06 Deere & Company Utility vehicle with front loader
US11047107B2 (en) 2018-05-02 2021-06-29 Deere & Company Utility vehicle having a front loader

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