WO2016169939A1 - Circuit hydraulique et engin de chantier - Google Patents

Circuit hydraulique et engin de chantier Download PDF

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Publication number
WO2016169939A1
WO2016169939A1 PCT/EP2016/058680 EP2016058680W WO2016169939A1 WO 2016169939 A1 WO2016169939 A1 WO 2016169939A1 EP 2016058680 W EP2016058680 W EP 2016058680W WO 2016169939 A1 WO2016169939 A1 WO 2016169939A1
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WO
WIPO (PCT)
Prior art keywords
valve
boom
hydraulic
control valve
channel
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.)
Ceased
Application number
PCT/EP2016/058680
Other languages
English (en)
Inventor
Kouji Kishida
Mitsuhiro Toyoda
Yoshihiko Hata
Yuya Kanenawa
Shuhei ORIMOTO
Nobuaki Matoba
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Caterpillar SARL
Original Assignee
Caterpillar SARL
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 Caterpillar SARL filed Critical Caterpillar SARL
Publication of WO2016169939A1 publication Critical patent/WO2016169939A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • 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
    • 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
    • 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
    • E02F9/2225—Control of flow rate; Load sensing arrangements using pressure-compensating valves
    • E02F9/2228—Control of flow rate; Load sensing arrangements using pressure-compensating valves including an electronic controller
    • 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
    • E02F9/2264—Arrangements or adaptations of elements for hydraulic drives
    • E02F9/2267—Valves or distributors
    • 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
    • E02F9/2264—Arrangements or adaptations of elements for hydraulic drives
    • E02F9/2271—Actuators and supports therefor and protection therefor
    • 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
    • E02F9/2278—Hydraulic circuits
    • E02F9/2285—Pilot-operated 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
    • E02F9/2278—Hydraulic circuits
    • E02F9/2296—Systems with a variable displacement pump
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/20—Other details, e.g. assembly with regulating devices
    • F15B15/202—Externally-operated valves mounted in or on the actuator
    • 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
    • E02F3/30—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 with a dipper-arm pivoted on a cantilever beam, i.e. boom
    • E02F3/32—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 with a dipper-arm pivoted on a cantilever beam, i.e. boom working downwardly and towards the machine, e.g. with backhoes
    • 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
    • E02F9/2278—Hydraulic circuits
    • E02F9/2292—Systems with two or more pumps

Definitions

  • the present invention relates to a hydraulic circuit provided with an accumulator, and a working machine equipped with the hydraulic circuit.
  • a working machine is configured to accumulate, in an accumulator, pressure oil that is discharged from a boom hydraulic cylinder when lowering the boom, and to also
  • a working machine often executes a so-called machine body lifting operation in which the front portion of the machine body is lifted by lowering the boom relative to the machine body while having the bucket grounded, in order to escape from a dip or soft ground or to lift the lower traveling bodies (crawlers) one by one and spin them when pebbles, dirt or the like are stuck in the lower traveling bodies (crawlers) one by one and spin them when pebbles, dirt or the like are stuck in the lower
  • the present invention was contrived in view of these circumstances, and an object thereof is to provide a hydraulic circuit and a working machine that are capable of effectively utilizing a working fluid ejected from a head of a hydraulic cylinder, to easily obtain, with a simple configuration, thrust, required for causing contraction of a hydraulic
  • An invention described in claim 1 is a hydraulic circuit having: a plurality of hydraulic cylinders that move a working device up and down by simultaneously actuating the same operation by using a working fluid that is pressurized and supplied by a pump in response to an operation of an operating device; an accumulator in which the working fluid is accumulated; an accumulation circuit that is provided with a first valve for changing the amount of communication between a head of a first hydraulic cylinder of the plurality of
  • a working fluid which is ejected from the head of the first hydraulic cylinder, in the accumulator through the first valve; a second valve that enables communication between rods of the plurality of hydraulic cylinders and communication between heads of the plurality of hydraulic cylinders when axial force of at least one of the hydraulic cylinders is egual to or greater than a predetermined level; a third valve that enables communication between the first valve and a tank to return the working fluid to the tank when the axial force of the at least one of the hydraulic cylinders is equal to or greater than the predetermined level; and a main valve that supplies the working fluid pressurized and supplied by the pump, to the rods of the plurality of hydraulic cylinders, while the first valve and the tank communicate with each other by the third valve.
  • An invention described in claim 2 is a hydraulic circuit according to claim 1, further having a detector for detecting the axial force of the at least one of the hydraulic cylinders based on a difference between a head pressure and a rod pressure of the hydraulic cylinder.
  • An invention described in claim 3 is a hydraulic circuit according to claim 1 or 2, wherein the second valve blocks the communication between the heads of the plurality of hydraulic cylinders and enables communication between the head of a second hydraulic cylinder of the plurality of hydraulic cylinders and rods of the first and second hydraulic cylinders when the axial force of the foregoing hydraulic cylinder is less than the predetermined level and the accumulation circuit accumulates the working fluid in the accumulator, and the hydraulic circuit further has a regenerative circuit that is provided with this second valve and regenerates a working fluid, which is ejected from the head of the second hydraulic cylinder, to the first and second hydraulic cylinders through the second valve.
  • An invention described in claim 4 is a working machine that has a machine body, a working device mounted in the machine body, and the hydraulic circuit described in any of claims 1 to 3 that is provided for a plurality of hydraulic cylinders moving the working device up and down.
  • the second valve in case of a large contraction load where the axial force ⁇ at least one of the hydraulic cylinders is equal to or greater than the predetermined level while the working fluid ejected from the head of the first hydraulic cylinder is accumulated in the accumulator by effectively utilizing the first valve of the accumulation circuit, the second valve enables the
  • the third valve enables the communication between the first valve and the tank to return the working fluid to the tank.
  • the working fluid pressurized and supplied by the pump is supplied to the rods of the plurality of hydraulic cylinders by the main valve. Therefore, the pressure
  • the axial force of at least one of the hydraulic cylinders can easily be detected based on the difference between the head pressure and the rod pressure of the hydraulic cylinder.
  • the regeneration flow rate of the pump at the time of the accumulation in the accumulator can be reduced, easily ensuring a necessary pump flow rate with a simple
  • predetermined level such as when lifting the machine body by lowering the working device relative to the machine body while the working fluid ejected from the head of the first hydraulic cylinder is accumulated in the accumulator by effectively utilizing the first valve of the accumulation circuit in order to lower the working device of the working machine, necessary thrust can easily be obtained with a simple configuration.
  • Fig. 1 is a circuit diagram showing a way of switching a hydraulic circuit according to an embodiment of the present invention.
  • Fig. 2 is a circuit diagram showing another way of switching the circuit.
  • Fig. 3 is a circuit diagram showing yet another way of switching the circuit.
  • Fig. 4 is a circuit diagram showing yet another way of switching the circuit.
  • Fig. 5 is an explanatory diagram schematically showing a control algorithm of a first valve of the circuit.
  • Fig. 6 is an explanatory diagram schematically showing a control algorithm of a second valve of the circuit.
  • Fig. 7 is an explanatory diagram schematically showing a control algorithm of a third valve of the circuit .
  • Fig. 8 is an explanatory diagram schematically showing a machine body lifting determination algorithm of the circuit.
  • Fig. 9 is an explanatory diagram schematically showing a machine body lifting determination algorithm of the circuit.
  • Fig. 9 is an explanatory diagram schematically showing a part of a flow rate control algorithm of a pump of the circuit.
  • Fig. 10 is an explanatory diagram schematically showing a part of a flow rate control algorithm of a pump of the circuit.
  • Fig. 10 is an explanatory diagram schematically showing another part of the flow rate control algorithm of the pump of the circuit.
  • Fig. 11 is an explanatory diagram schematically showing a control algorithm .of an engine power assist function of the circuit .
  • Fig. 12 is a perspective view showing a working machine provided with this hydraulic circuit.
  • a hydraulic excavator HE which is a working machine, has a machine body 1 that is configured by a lower traveling body 2 and an upper slewing body 3 provided thereon so as to be slewable by a slewing motor 3m, wherein the upper slewing body 3 is equipped with a machine room 4 equipped with the engine, a pump and the like, a cab 5 for protecting an operator, and a working device 6.
  • a base end of a boom 7 that is rotated vertically by two parallel boom cylinders 7cl, 7c2 functioning as hydraulic cylinders is axially supported on the upper slewing body 3
  • a stick 8 that is rotated back and forth by a stick cylinder 8c is axially supported at a tip of the boom 7, and a bucket 9 that is rotated by a bucket
  • cylinder 9c is axially supported at a tip of the stick 8.
  • the two boom cylinders 7cl, 7c2 are provided parallel to the common boom 7 and simultaneously actuate the same operation.
  • Fig. 1 to Fig. 4 each show an engine power assist system that accumulates position energy of the working device 6 in an accumulator through the boom cylinder 7cl, accumulates kinetic energy of the upper slewing body 3 in the accumulator through the slewing motor 3m, and uses these energies to assist engine power.
  • An assist motor 15 is connected to a main pump shaft 14 of main pumps 12, 13 directly or by a gear, the main pumps 12, 13 being driven by a built-in engine 11 of the machine room 4.
  • the main pumps 12, 13 and the assist motor 15 each have a swash plate capable of variably adjusting the
  • the regulators 16, 17, 18 are
  • the regulators 16, 17 of the main pumps 12, 13 can be controlled by a solenoid valve.
  • the regulators 16, 17 of the main pumps 12, 13 can be controlled
  • negative control pressure a negative flow control pressure guided through a negative flow control channel 19nc or with a signal other than the negative control pressure by solenoid switching valves 19a, 19b of a negative flow control valve 19 functioning as a flow rate control valve -
  • the main pumps 12, 13 discharge, to channels 22, 23, hydraulic oil which is a working fluid drawn up from a tank 21, and have the pump discharge pressures thereof detected by pressure sensors 24, 25.
  • Pilot control valves for controlling the directions and flow rates of the hydraulic oil are connected to the main pumps 12, 13.
  • the pilot control valves include a boom control valve 26 as a main valve for
  • An output channel 27 extending from the boom control valve 26 and an output channel 29 extending from the boom control valve 28 are connected to a boom energy recovery valve 31, which is a composite valve, by a channel 30.
  • This boom energy recovery valve 31 is a composite valve that incorporates a plurality of circuit functions in a single block, the plurality of circuit functions being used for switching an accumulation circuit A, a regenerative circuit B, a bleed-off circuit C, which are shown in Figs. 1 to 3, and a circuit that guides the hydraulic oil, which is pressurized and supplied by the main pumps 12, 13 in a boom lifting operation shown in Fig. 4, to heads of the two boom cylinders 7cl, 7c2.
  • a channel 32 extending from a head-side end of the boom cylinder 7cl is connected to the boom energy recovery valve 31 by a channel 34 through a drift reduction valve 33, and a channel 35 extending from a head-side end of the boom cylinder 7c2 is connected to the boom energy recovery valve 31 by a channel 37 through a drift reduction valve 36.
  • An output channel 38 extending from the main boom control valve 26 is connected to the regenerative circuit B of the boom energy recovery valve 31.
  • the rods of the boom cylinders 7cl, 7c2 are connected to the boom energy recovery valve 31 by channels 39, 40.
  • the drift reduction valves 33, 36 control the
  • a tank channel 50 extending from an accumulator channel 47 provided with a plurality of first accumulators 46 is connected to the suction side of the assist motor 15 through a relief valve 48 and a check valve 49, and a suction-side channel 52 extending from the accumulator channel 47 is connected to the same through a solenoid switching valve 51.
  • a pressure sensor 55 for detecting pressure accumulated in the first accumulators 46 is connected to the accumulator channel 47.
  • the tank channel 50 extends through a tank channel 56, a spring check valve 57, and an oil cooler 58 or a spring check valve 59 and is connected to the tank 21.
  • the first accumulators 46, the accumulator channel 47, the relief valve 48, the solenoid switching valve 51, and the pressure sensor 55 are
  • the boom energy recovery valve 31 has a control valve 61 that is a first valve configuring a part of the accumulation circuit A, a main control valve 62 that is a second valve functioning as a boom circuit switching valve to configure a part of the regenerative circuit B, and a bleed- off valve 63 that is a third valve configuring a part of the bleed-off circuit C. Pilot-operated valves are used as these valves 61 to 63, the pilot-operated valves being switched when the solenoid switching valves are operated by, for example, the operator in the cab 5 (Fig.
  • control valves 61 to 63 are shown as solenoid proportional direction control valves in the diagrams.
  • the control valve 61 is a flow rate control valve that allows the hydraulic oil from the boom cylinder 7cl to be accumulated in the first accumulators 46, by switching between enabling and blocking the communication between the channels 68 and 34 connected to the first accumulators 46 (the
  • the main control valve 62 is configured to block the communication between the heads of the boom cylinders 7cl, 7c2 and enables the communication between the head of the boom cylinder 7c2 and the rods of the boom cylinders 7cl, 7c2 at the time of accumulation in the first accumulators 46 by switching the control valve 61.
  • the channel 30 is connected to the channel 71 through a check valve 78.
  • the channel 72 is connected to the channel 37 and a channel 79 branching off from the channel 30.
  • the channel 73 branches off from the channel 72.
  • the channel 74 is connected to the channel 40 through a check valve 80.
  • the channel 75 is connected to the output channel 38 and the channel 39, and the channel 76 branches off from the channel 40.
  • the bleed-off valve 63 is for switching the
  • this bleed- off valve 63 is configured to enable the communication between the control valve 61 and the tank 21 in the initial stage of switching the control valve 61 or when lifting the machine body 1 (Fig.
  • predetermined short time period e.g., 0.5 seconds
  • the accumulation circuit A is a circuit where the hydraulic oil flows from the channel 32 extending from the head-side end of the boom cylinder 7cl, passes through the drift reduction valve 33, the channel 34, the control valve 61 and check valve 67 of the boom energy recovery valve 31, and the channel 68, and reaches the first accumulators 46.
  • the accumulation circuit A is a circuit where the hydraulic oil flows from the channel 32 extending from the head-side end of the boom cylinder 7cl, passes through the drift reduction valve 33, the channel 34, the control valve 61 and check valve 67 of the boom energy recovery valve 31, and the channel 68, and reaches the first accumulators 46.
  • the regenerative circuit B is a circuit where the hydraulic oil flows from the channel 35 extending from the head-side end of the boom cylinder 7c2, passes through the drift reduction valve 36, the channel 37, the channel 73, main control valve 62, channel 74, check valve 80, and channel 40 of the boom energy recovery valve 31, reaches the rod-side end of the boom cylinder 7c2, flows again from the channel 35, passes through the drift reduction valve 36, the channel 37, the channel 73, main control valve 62, channel 74, check valve 80, channel 76, main control valve 62, channel 75, and channel 39 in the boom energy recovery valve 31, and then reaches the rod-side end of the boom cylinder 7cl.
  • the regenerative circuit B functions to regenerate, to the rods of the boom cylinders 7cl, 7c2, thehydraulic oil ejected from the head of the boom cylinder 7c2.
  • the bleed-off circuit C is a circuit branching off from the accumulation circuit A, in which the hydraulic oil reaches the tank 21 through the control valve 61, channel 82, bleed-off valve 63, and channel 83 of the boom energy recovery valve 31.
  • the bleed-off circuit C functions to return the hydraulic oil, which is ejected from the head of the boom cylinder 7cl, to the tank 21 at initial operation of the control valve 61, that is, in the initial stage of contraction of the boom cylinders 7cl, 7c2, the initial stage of a boom lowering operation, or when lifting the machine body 1 (Fig. 12) .
  • Relief valves 94, 95 and check valves 97, 98 that are mutually opposite to each other are provided between channels 92, 93 of a motor drive circuit D that connects a slewing control valve 91 and the slewing motor 3m to each other, the slewing control valve 91 controlling the slewing direction and speed of the slewing motor 3m.
  • a makeup channel 99 which has a tank channel function for returning the oil discharged from the motor drive circuit D to the tank 21 and a makeup function capable of replenishing the motor drive circuit D with hydraulic oil, is connected between the relief valves 94, 95 and between the check valves 97, 98.
  • the makeup channel 99 is connected to a second accumulator 100 that supplies pressure oil. Hydraulic oil is replenished in the channel 92 or 93, whichever is likely to cause a vacuum, from the makeup channel 99 through the check valves 97, 98 at a pressure that does not exceed the spring biasing force of the spring check valve 57.
  • the channels 92, 93 of the motor drive circuit D are made to communicate with a slewing energy recovery channel 104 by check valves 102, 103.
  • This channel 104 is connected to a channel 106 through a sequence valve 105 where the source pressure at the inlet thereof does not change easily due to the back pressure at the outlet of the same.
  • the channel 106 is connected to the first accumulators 46 and the channel 68.
  • the swash plate angle sensors 16 ⁇ , 17 ⁇ , 18 ⁇ and the pressure sensors 24, 25, 55 input the detected swash plate angle signals and pressure signals to an in-vehicle controller CR (Fig. 12) that functions as a detector and a machine body lifting
  • the boom control valves 26, 28, the slewing control valve 91, and other hydraulic actuator control valves that are not shown are pilot-operated by a manually operated valve which is a so-called remote-control valve operated by the operator in the cab 5 (Fig. 12) or the like operating the lever or pedal.
  • the pilot valves of the drift reduction valves 33, 36, which are not shown, are also pilot-operated in conjunction with the foregoing valves.
  • Fig. 2 and Fig. 3 each show a state of the circuit in which the boom lowering operation for lowering the boom 7 (Fig. 12) is performed.
  • the hydraulic oil that is ejected from the head of the boom cylinder 7cl due to a load or the like of the working device 6 (Fig. 12) passes through the channel 32, the drift reduction valve 33, and the channel 34, and is returned from the control valve 61 of the boom energy recovery valve 31 that is switched to the communication position, to the tank 21 (Fig. 2) by the bleed-off valve 63 switched to the communication position in the initial stage.
  • the hydraulic oil is further made to communicate with the channel 68 from the control valve 61 through the check valve 67 when the bleed-off valve 63 is switched to the blocking position based on a predetermined condition such as a lapse of a predetermined time period. From the channel 68, the hydraulic oil is then accumulated in the first accumulators 46 (Fig. 3) .
  • the control valve 61 switches the amount of communication between the head of the boom cylinder 7cl and the first accumulators 46, in accordance with the operation amount of the lever, i.e., the pilot pressure set based on this operation amount, and the accumulator pressure of the first accumulators 46 detected by the pressure sensor 55. Specifically, the pilot pressure that is set based on the operation amount of the lever is corrected based on a
  • the amount of increase in the output pressure with respect to the amount of increase in the input pressure is reduced more compared to when the pilot pressure is equal to or lower than the threshold THl. Furthermore, in the region where the pilot pressure exceeds a predetermined threshold TH2 that is greater than the
  • the output pressure is set constant. Furthermore, according to the table T2, in the region where the accumulator pressure is equal to or lower than a predetermined threshold TH3, a gain increases with respect to the amount of increase in the accumulator pressure, and in the region where the accumulator pressure exceeds the predetermined threshold TH3, the gain is set constant (e.g., 1) . In this case, the hydraulic oil is prevented by the check valve 78 from returning toward the boom control valve 26.
  • the boom lowering operation includes the machine body lifting operation for lifting the front portion of the machine body 1 (Fig. 12) by lowering the boom 7 (Fig. 12) relative to the machine body 1 (Fig. 12) while having the bucket 9 (Fig. 12) grounded.
  • the operations of the main control valve 62, the bleed-off valve 63, and the boom control valve 26 can be made different than those that are performed when other boom lowering operations are executed (Fig. 1) .
  • the in-vehicle controller CR causes a pressure sensor (not shown) to detect the head pressure and the rod pressure of at least either one of the boom cylinders 7cl, 7c2, e.g., the boom cylinder 7cl, uses calculators CI, C2 to calculate not only a head-side load and a rod-side load of the boom cylinder 7cl based on these head pressure and rod pressure, but also axial force based on the difference between the head-side load and the rod-side load.
  • the bleed-off valve 63 switches the amount of communication between the control valve 61 and the tank 21, in accordance with the operation amount of the lever, i.e., the pilot pressure set based on this operation amount, the
  • a base pressure which is set based on a predetermined table (converter) T3 in accordance with the pilot pressure that is set based on the operation amount of the lever
  • a gain which is set based on a predetermined table (converter) T4 for accelerating the lowering of the boom in accordance with a predetermined short time period at the start of the boom lowering operation that is measured by a time counter TCI, such as a lapse of 10 ms
  • a gain that is set based on a predetermined table (converter) T5 in accordance with the accumulator pressure are integrated together, and this resultant integrated value is obtained as an output for operating the bleed-off valve 63.
  • the integrated value is taken as a predetermined output (e.g., 4000 kPa) for completely opening the bleed-off valve 63.
  • a predetermined output e.g. 4000 kPa
  • the amount of increase in the output pressure becomes relatively greater than the amount of increase in the pilot pressure.
  • the amount of increase in the output pressure with respect to the amount of increase in the input pressure is reduced more compared to when the pilot pressure is equal to or lower than the threshold TH4.
  • the output pressure is set constant.
  • the gain increases as time measured by the time counter TCI passes, and between the time where the pilot pressure exceeds a predetermined threshold TH6 and the time where the pilot pressure is equal to or lower than a predetermined threshold TH7 greater than the
  • the gain is set constant. For a predetermined time period after the predetermined threshold TH7, such as for 0.5 ms, the gain decreases as time passes. In the table T5, the gain is set constant with respect to the amount of increase in the accumulator pressure.
  • the main control valve 62 in the boom lowering operation other than the machine body lifting operation, controls the direction of the hydraulic oil ejected from the head of the boom cylinder 7c2, in such a manner that the hydraulic oil flows from the channel 35, passes through the drift reduction valve 36, the channel 37, and the main control valve 62, channel 73, and channel 74 of the boom energy recovery valve 31, and is regenerated to the rod of the boom cylinder 7c2 through the check valve 80 and the channel 40.
  • the main control valve 62 further controls the direction of the hydraulic oil splitting into the channel 76 through the check valve 80, in such a manner that the hydraulic oil flows to the channel 75 through the check valve of the main control valve 62 and is regenerated to the rod of the boom cylinder 7cl through the channel 39.
  • the main control valve 62 enables the communication between the heads of the boom cylinders 7cl, 7c2 and communication between the rods of the same, supplies the hydraulic oil, which is supplied from the main pump 12 through the boom control valve 26, to the rods of the boom cylinders 7cl, 7c2, and returns the hydraulic oil, which is ejected from the heads of the boom cylinders 7cl, 7c2, to the tank 21 through the control valve 61, the channel 82, the bleed-off valve 63, and the channel 83.
  • the operation amount of the main control valve 62 is changed in accordance with the operation amount of the lever, i.e., the pilot pressure set based on this operation amount, and the machine body lift flag.
  • the pilot pressure that is set based on the operation amount of the lever is corrected based on a predetermined table
  • the boom energy recovery valve 31 causes the control valve 61 and the main control valve 62 to accumulate the hydraulic oil in the first accumulators 46 at the time of the boom lowering operation other than the machine body lifting operation and at the same time regenerate the hydraulic oil to the rods of the boom cylinders 7cl, 7c2.
  • the boom energy recovery valve 31 stops the accumulation of the hydraulic oil in the first accumulators 46 and the regeneration of the hydraulic oil to the rods of the boom cylinders 7cl, 7c2.
  • the pump flow rate from the main pump 12 controlled by the boom control valve 26 to the boom cylinder 7cl (and boom cylinder 7c2) is set by the solenoid switching valve 19a of the negative flow control valve 19 in accordance with the operation amount of the lever, i.e., the pilot pressure that is set based on this operation amount, the accumulator
  • the base flow rate of this pump flow rate is set as follows.
  • the minimum value of a flow rate that is set based on a predetermined table (converter) T7 in accordance with the pilot pressure set based on the operation amount of the lever is obtained, as well as the minimum value of a flow rate that is set based on a predetermined table (converter) T8 in accordance with a predetermined short time period at the start of the boom lowering operation that is measured by a time counter TC2, such as a lapse of 10 ms .
  • predetermined table (converter) T9 in accordance with a predetermined short time period at the start of the boom lowering operation that is measured by the time counter TC2, such as a lapse of 10 ms, is integrated with a gain that is set based on a predetermined table (converter) T10 in accordance with the pilot pressure that is set based on the operation amount of the lever.
  • the foregoing minimum values or the resultant integrated value, whichever is bigger, is set as the base flow rate.
  • the flow rate is set constant in the region where the pilot pressure that is set based on the operation amount of the lever is egual to or lower than a predetermined threshold TH8.
  • the flow rate decreases in proportion to an increase in the pilot pressure.
  • the flow rate is set constant in the region where the pilot pressure exceeds the predetermined threshold TH9.
  • the flow rate increases as time measured by the time counter TC2 passes, and the flow rate is set constant from the time where the pilot pressure exceeds a predetermined threshold TH10.
  • the flow rate increases as time measured by the time counter TC2 passes, and then the flow rate is set
  • the flow rate decreases as time passes.
  • the gain increases in proportion to an increase in the pilot pressure, and the gain is set constant (e.g., 1) in the region where the pilot pressure exceeds a predetermined threshold TH13.
  • a flow rate that is obtained by integrating the base flow rate described above with a gain that is set based on the predetermined table (converter) Til in accordance with the accumulator pressure is set as the foregoing pump flow " rate for the boom lowering operation alone.
  • a lever operation such as a stick-in, operation, a stick-out operation, a bucket-in operation, or a bucket-out operation is performed simultaneously with the boom lowering operation, flow rates that are set based on predetermined tables (converters) T12 to T15 in accordance with the pilot pressures set based on these operations are added up.
  • a predetermined machine body lifting flow rate is set as the pump flow rate for the boom lowering operation alone, and when a lever operation such as a stick-in operation, a stick- out operation, a bucket-in operation, or a bucket-out
  • the operation is performed simultaneously with the boom lowering operation, flow rates that are set based on the predetermined tables T12 to T15 in accordance with the pilot pressures set based on these operations are added up.
  • the gain is set constant (e.g., 1) when the accumulator pressure is equal to or lower than a predetermined threshold TH1 . In the region where the accumulator pressure exceeds the
  • predetermined threshold TH14 when the accumulator pressure is relatively small, the amount of increase in the gain is relatively greater than the amount of increase in the
  • the accumulator pressure In the region where the accumulator pressure exceeds the predetermined threshold TH14 but is equal to or lower than a predetermined threshold TH15 that is greater than the predetermined threshold TH14, the amount of increase in the gain with respect to the amount of increase in the accumulator pressure is reduced more compared to when the accumulator pressure is equal to or lower than the threshold TH14. Furthermore, in the region where the accumulator pressure exceeds a predetermined threshold TH16 that is greater than the predetermined threshold TH15, the gain is ' set constant (greater than 1) .
  • each of the tables T12 to T15 in the region where the pilot pressure set by the operation amount of the lever is equal to or lower than a predetermined threshold TH17, the amount of increase in the flow rate is relatively greater than the amount of increase in the pilot pressure, and in the region where the pilot pressure exceeds the predetermined threshold TH17 but is equal to or lower than a predetermined threshold TH18 that is greater than the predetermined threshold TH17, the amount of increase in the flow rate with respect to the amount of increase in the pilot pressure is reduced more compared to when the pilot pressure is equal to or lower than the threshold TH17. Furthermore, in the region where the pilot pressure exceeds the predetermined threshold TH18, the flow rate is set constant.
  • These tables T12 to T15 may be identical or have the values of the
  • FIG. 4 shows a state of the circuit in which the boom lifting operation for raising the boom 7 (Fig. 12) is performed.
  • the boom energy recovery valve 31 not only switches the control valve 61 to the blocking position but also switches the main control valve 62 to stop the accumulation of the hydraulic oil in the first accumulators 46 and the regeneration of the same to the rods of the boom cylinders 7cl, 7c2.
  • the direction of the hydraulic oil ejected from the rod of the boom cylinder 7c2 is controlled to allow the hydraulic oil to flow to the channel 75 through the channel 40, the channel 76, and the main control valve 62, thereby returning the hydraulic oil to the tank 21 from the output channel 38 through the boom control valve 26.
  • engine power assist can be performed in which the assist motor 15 with a motor function, which is coupled to the main pump shaft 14 directly or by a gear, is caused to
  • the engine power assist is performed when the pressure sensor 55 detects that the accumulator pressure of the first
  • the engine power assist is performed when the pressure sensor 55 detects that the accumulator pressure of the first accumulators 46 is equal to or greater than a predetermined second threshold different from the predetermined first threshold.
  • the solenoid switching valve 51 is switched to the communication position, and the assist motor 15 is rotated by the energy accumulated in the first accumulators 46, to assist the hydraulic outputs of the main pumps 12, 13 and reduce the engine load.
  • the engine power assist is not performed using the assist motor 15.
  • the flag 0 is output and the solenoid switching valve 51 is switched to the blocking position.
  • the flag is switched from 0 to 1 when the accumulator pressure increases to become egual to or greater than the threshold TH20, and the flag is switched from 1 to 0 when the accumulator pressure decreases to become equal to or lower than the threshold TH19.
  • the table T17 in which a
  • predetermined threshold TH21 greater than the predetermined threshold TH20 and a predetermined threshold TH22 greater than the predetermined threshold TH21 are set, the flag is switched from 0 to 1 when the accumulator pressure increases to become equal to or greater than the threshold TH22, and the flag is switched from 1 to 0 when the accumulator pressure decreases to become equal to or lower than the threshold TH21.
  • These tables T16 and T17 therefore, each have so-called hysteresis in which the thresholds vary depending on the increase and decrease of the accumulator pressure.
  • the engine power assist function reduces, by using the assist motor 15, the load of the built-in engine 11 that is coupled thereto by the main pump shaft 14.
  • the main control valve 62 is switched to the position for enabling the communication between the heads of the boom cylinders 7cl, 7c2 and communication between the rods of the same, the bleed- off valve 63 is switched to the communication position, the accumulation of the hydraulic oil in the first accumulators 46 is canceled, the communication between the heads of the boom cylinders 7cl, 7c2 and communication between the rods of the same are enabled, the hydraulic oil ejected from the heads is returned to the tank 21 by means of the bleed-off circuit C, the hydraulic oil is supplied from the main pump 12 to the rods of the boom cylinders 7cl, 7c2 through the boom control valve 26 in a predetermined machine body lifting flow rate, and the solenoid switching valve 51 is switched to the
  • the main control valve 62 enables the communication between the rods of the boom
  • accumulators 46 can be reduced, and the necessary pump flow rate including the main pump flow rates required by the other hydraulic actuators can easily be ensured with a simple configuration. Moreover, the size of the main pumps 12, 13 can be reduced.
  • the generated from the boom cylinder 7cl can be increased, resulting in an increase in the energy to be accumulated in the first accumulators 46.
  • the sizes of the components such as the first accumulators 46 and the assist motor 15 can be reduced, resulting in a cost reduction and a simple layout of the circuit.
  • 7cl, 7c2 can easily be detected based on the difference between the head pressure and the rod pressure of at least either one of the boom cylinders 7cl, 7c2.
  • control valve 61 changes the amount of communication between the head of the boom cylinder 7cl and the first accumulators 46 in accordance with the operation amount of the lever and the accumulator pressure of the first accumulators 46.
  • the flow rate of the hydraulic oil discharged from the main pumps 12, 13 to the rod of the boom cylinder 7cl can be reduced by effectively regenerating the hydraulic oil to the rod of the boom cylinder 7cl, ensuring the necessary pump flow rate more easily.
  • boom energy recovery valve 31 configured by integrating the plurality of circuit functions into a single block, not only is it possible to obtain a simple layout, but also a cost reduction can be achieved by reducing the number of assembly steps.
  • concentrating a load on the boom cylinder 7cl alone can increase the energy to be accumulated in the first accumulators 46. Therefore, substantial assist can be performed with a small accumulator, resulting in a cost reduction and a compact machine body layout .
  • the present invention is industrially applicable to all businesses that are concerned in manufacturing and sales of hydraulic circuits or working machines.

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

Abstract

L'invention concerne un circuit hydraulique et un engin de chantier, un fluide hydraulique poussé hors d'un côté de tête d'un vérin hydraulique pouvant être utilisé efficacement pour être accumulé dans un accumulateur, et une poussée nécessaire pour contracter le vérin hydraulique étant obtenue facilement au moyen d'une structure simple lorsque la charge de contraction est grande. Une huile sous pression provenant d'un côté de tête d'un vérin de flèche (7cl) est accumulée dans un premier accumulateur (46) avec un circuit d'acclimatation de pression (A) à l'aide d'une soupape de commande (61) qui change une amplitude de communication entre le côté de tête du vérin de flèche (7cl) et le premier accumulateur (46) en fonction du degré de fonctionnement d'un levier. Lorsque la force axiale des vérins de flèche (7cl), (7c2) est égale ou supérieure à une valeur prédéterminée, l'huile hydraulique est renvoyée vers un réservoir (21) en communiquant entre des côtés de tige et entre des côtés de tête des vérins de flèche (7cl), (7c2) par une soupape de commande principale (62), et l'huile hydraulique est acheminée vers le côté de tige des vérins de flèche (7cl), (7c2) par une soupape de commande de flèche (26), l'huile hydraulique étant acheminée sous pression depuis une pompe principale (12) dans l'état dans lequel la soupape de commande (61) et le réservoir (21) communiquent par une soupape de purge (63).
PCT/EP2016/058680 2015-04-21 2016-04-20 Circuit hydraulique et engin de chantier Ceased WO2016169939A1 (fr)

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JP2015086580A JP6601835B2 (ja) 2015-04-21 2015-04-21 流体圧回路および作業機械

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WO2018174084A1 (fr) * 2017-03-21 2018-09-27 日立建機株式会社 Machine de construction
US11286644B2 (en) 2018-08-23 2022-03-29 Kobe Steel, Ltd. Hydraulic actuator for excavation work machine
US11293163B2 (en) 2018-08-23 2022-04-05 Kobe Steel, Ltd. Hydraulic drive device for excavation work machines
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JP6493916B2 (ja) * 2015-04-21 2019-04-03 キャタピラー エス エー アール エル 流体圧回路および作業機械
CN107939752B (zh) * 2017-10-10 2019-11-26 三一重机有限公司 制动节能液压系统及挖掘机
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JP4702894B2 (ja) * 2006-10-20 2011-06-15 キャタピラー エス エー アール エル 油圧ショベルにおける油圧制御システム
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