EP3595847A1 - Hydraulic control circuit with flow summation in presence of single or double effect auxiliary equipments of a construction vehicle - Google Patents

Hydraulic control circuit with flow summation in presence of single or double effect auxiliary equipments of a construction vehicle

Info

Publication number
EP3595847A1
EP3595847A1 EP18711324.6A EP18711324A EP3595847A1 EP 3595847 A1 EP3595847 A1 EP 3595847A1 EP 18711324 A EP18711324 A EP 18711324A EP 3595847 A1 EP3595847 A1 EP 3595847A1
Authority
EP
European Patent Office
Prior art keywords
control
equipment
effect
valve
line
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.)
Granted
Application number
EP18711324.6A
Other languages
German (de)
French (fr)
Other versions
EP3595847B1 (en
Inventor
Francesco CHIOCCOLA
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.)
CNH Industrial Italia SpA
Original Assignee
CNH Industrial Italia SpA
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 CNH Industrial Italia SpA filed Critical CNH Industrial Italia SpA
Publication of EP3595847A1 publication Critical patent/EP3595847A1/en
Application granted granted Critical
Publication of EP3595847B1 publication Critical patent/EP3595847B1/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • 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
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • 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
    • 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
    • E02F9/2292—Systems with two or more pumps
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20546—Type of pump variable capacity
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/20576—Systems with pumps with multiple pumps
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30525—Directional control valves, e.g. 4/3-directional control valve
    • F15B2211/3053—In combination with a pressure compensating valve
    • F15B2211/30555—Inlet and outlet of the pressure compensating valve being connected to the directional control valve
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/3056—Assemblies of multiple valves
    • F15B2211/3059—Assemblies of multiple valves having multiple valves for multiple output members
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/3056—Assemblies of multiple valves
    • F15B2211/3059—Assemblies of multiple valves having multiple valves for multiple output members
    • F15B2211/30595—Assemblies of multiple valves having multiple valves for multiple output members with additional valves between the groups of valves for multiple output members
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/32—Directional control characterised by the type of actuation
    • F15B2211/329—Directional control characterised by the type of actuation actuated by fluid pressure
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/6306—Electronic controllers using input signals representing a pressure
    • F15B2211/6316—Electronic controllers using input signals representing a pressure the pressure being a pilot pressure
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7052—Single-acting output members
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7053—Double-acting output members
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
    • F15B2211/7135—Combinations of output members of different types, e.g. single-acting cylinders with rotary motors
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
    • F15B2211/7142—Multiple output members, e.g. multiple hydraulic motors or cylinders the output members being arranged in multiple groups

Definitions

  • the present invention relates to an hydraulic control circuit for operation of an auxiliary equipment of a construction vehicle, such as a loader, excavator, mini-excavator or the like.
  • the hydraulic circuit controls and powers both a single effect auxiliary equipment, such as a hammer, and a double effect auxiliary equipment, such as a crusher.
  • a construction vehicle may be provided with a control circuit having a flow summation function for one of its actuators.
  • the flow dedicated to a non-used power line/ power port of control valve is redirected to a preferred actuator in order to increase actuation speed of one effect of the preferred actuator.
  • a mini-excavator comprising a boom and an auxiliary attachment for a single effect actuator such as a hammer
  • the flow summation is realized to increase the speed of a boom-up function.
  • a construction vehicle is often provided with interchangeable auxiliary equipment that may be a single effect hydraulic actuator or a double effect actuator such as a crusher.
  • a single effect equipment is controlled via a power line connected to a pressure source and a return line directly connected to a tank or to a return line; and a double effect equipment is controlled via a first and a second power line that are selectively connected to a power source and to the sump depending on the controlled effect.
  • a construction equipment vehicle may be provided with the control circuit cited above.
  • FIG. 1 is a scheme of a simplified control circuit according to the present invention, where only components for the understanding of the invention are shown;
  • FIG. 2 is a scheme of a simplified control circuit according to a second
  • Figure 1 refers, as a whole, to a control circuit 1 for a construction vehicle, e.g. a mini- excavator, comprising a source of pressurized fluid having preferably a first and a second pump PI, P2 each of which is connected, via respective feed lines FL1, FL2, to a control section of the circuit comprising a first and a second control valve 1, 2.
  • Valves PV branch off from feed lines FL1, FL2 to direct unnecessary fluid to a tank in order to maintain a pre-set maximum pressure limit at the outlet of pumps PI , P2.
  • control valve 1 controls an actuator B via a first and a second power line PLA1, PLA2.
  • Each power line PLA1, PLA2 is associated to a respective effect of the actuator so that, when one power line is connected to the source of pressurized fluid to operate an effect of actuator B, the other power line is connected to tank.
  • Actuator B may be either a single or a double effect actuator. In the example, actuator B is a double effect actuator to control a boom of the construction vehicle.
  • Control valve 2 controls an auxiliary equipment C, H of the construction vehicle via a power line LI that is associated to one effect of the equipment.
  • Control valve 2 is also connected to first power line PLA1 via an interconnection I in order to provide flow- summation to the effect associated to power line PLA1.
  • flow- summation is associated to a boom-up function.
  • Control section of circuit 1 also comprises a power line L2 attached to the auxiliary equipment C, H and a switch valve 3 to intercept interconnection I, power line L2 and a return line preferably connected to a tank.
  • Control circuit 1 also comprises a piloting section comprising hydraulic commands for commutation of control valves 1, 2 and switch valve 3 when a user, via e.g. a joystick or the like, controls actuator B and equipment C, H from a cockpit or driver's seat of the construction vehicle.
  • a piloting section comprising hydraulic commands for commutation of control valves 1, 2 and switch valve 3 when a user, via e.g. a joystick or the like, controls actuator B and equipment C, H from a cockpit or driver's seat of the construction vehicle.
  • piloting section comprises a first and a second control valve pilot line CVPL1, CVPL2 to switch first control valve 1 from a neutral and closed position to respective first and second working position PB 1 , PB2 upon manual commands by the user.
  • first working position PB 1 is associated to a high speed effect of actuator B such as, according to the embodiment of figure 1 , the effect corresponding to boom-up.
  • piloting section also comprises a pilot switch valve 4 having a first input receiving a pressure command from first control valve pilot line CVPL 1 via a T-branch Tl, and a second input receiving a pressure command for equipment C, H.
  • Output of pilot switch valve 4 is such to switch second control valve 2 from a neutral and closed position to a first working position PCH1 to feed interconnection I.
  • Second control valve 2 has a second working PCH2 position to feed a first effect of equipment C, H via first power line LI . Switch to such second working position of second control valve 2 is piloted via a third control valve pilot line CVPL3.
  • pilot switch valve 4 In a neutral position, pilot switch valve 4 is such to enable the switch of second control valve 2 to feed interconnection I when a user pressurizes first control valve pilot line CVPL1 to provide flow summation for the first effect of actuator B. In such a condition, switch valve 3 as well is a neutral position such that interconnection I feeds power line PLA1 of actuator B. Furthermore, pilot switch valve 4 may switch to a further position where flow summation is excluded and first working position PCH1 of second control valve 2 is reached when equipment C is a double effect equipment and the user commands a second effect of equipment C, e.g. a crusher. It is worth noting that the first effect of equipment C, H via power line LI is associated to second working position PCH2 of second control valve 2 via third control valve pilot line CVPL3.
  • Pilot switch valve 4 switches from neutral position to the further position via a shuttle valve 5 that outputs the higher pressure signal between third control valve pilot line CVPL3 and a user's command for the second effect of equipment C when the latter is a double-effect actuator.
  • shuttle valve 5 receives the signal from third control valve pilot line CVPL3 via a first pilot line PL1 and the signal for the second effect of equipment C via a second pilot line PL2.
  • Piloting section also comprises a junction Jl where second pilot line PL2 meets a third pilot line PL3 to switch valve 3.
  • Junction Jl is also connected to second input of pilot switch valve 4 and to the user's command for the second effect of equipment C.
  • a selector valve 6 has a first stable position that pressurizes junction Jl so that both second pilot line PL2 and third pilot line PL3 cause commutation of pilot switch valve 4 and switch valve 3 respectively. This enables the second effect of equipment C.
  • Selector valve 6 has a second stable position to vent junction Jl . Accordingly, switch valve 3 and pilot switch valve 4 are kept by respective springs in the configuration such to provide flow-summation.
  • first control valve 1 is switched by the user acting on e.g. a joystick to provide alternate pressure commands on first and second control valve pilot lines CVPL1, CVPL2 to respectively activate actuator B first effect, i.e. high speed effect, and second effect, where available.
  • actuator B first effect i.e. high speed effect
  • second effect where available.
  • high speed effect corresponds to 'boom- up' function.
  • second control valve 2 Upon command signal via first control valve pilot line CVPL1, second control valve 2 is switched to first working position PCH1 via T-junction Tl in order to provide flow- summation to the high speed effect of actuator B, i.e. flow across second control valve 2, i.e. a proportional valve, is directed to power line PLA1 via interconnection I. Flow-summation is possible only when equipment C, H is not actuated by the operator.
  • second control valve 2 switches to second working position PCH2 that vents interconnection I and feeds power line LI .
  • power line L2 is vented via switch valve 3.
  • a check valve 7 is provided between power line PL1 and second control valve 2. According to the embodiment of figure 1, check valve 7 is along
  • Equipment C, H is detachable from power lines LI, L2 depending on the use of the vehicle.
  • selector valve 6 can be a bi-stable lever or button on a dashboard of the vehicle or the joystick.
  • selector valve 6 In particular, the position of selector valve 6 such that junction Jl is vented, inhibits any feed to power line L2 and, thus, the second effect of the equipment. Therefore the user sets selector valve 6 to stably vent junction Jl when a single effect equipment such as a hammer is attached to the construction vehicle.
  • junction Jl splits a single command signal for the second effect of equipment C to affect both pilot switch valve 4 and switch valve 3.
  • control circuit Accordingly, Advantages of the control circuit according to the present invention are as follows.
  • Via switch valve 3 it is possible to add a further degree of flexibility so as to control at the same time flow summation for a first actuator and both a single and a double effect auxiliary equipment.
  • shuttle valve 5 When control section is piloted by pressure command signals via the piloting section, the provision of shuttle valve 5 provides for the use of a single component, i.e. pilot switch valve 4, to select the correct command signal to enable/disable actuation of the second effect of the auxiliary equipment.
  • selector valve 6 safely ensures that commands are properly associated to a single effect auxiliary equipment or a double effect auxiliary equipment.
  • junction Jl efficiently splits the command signal to reach both pilot switch valve 4 and switch valve 3.
  • actuator may be an actuator of a further auxiliary equipment enjoying a flow- summation function.
  • Actuator B and the further auxiliary equipment can be both single or double effect.
  • switch valve 3 shall be provided having a first position to intercept interconnection I and to vent power line L2 and a second position to close interconnection I and connect power line L2 to a source of pressurized fluid.
  • a further step is to provide, within a piloting section, the shuttle valve 5.
  • An even further step is to provide, within the piloting section, the selector valve 6.
  • control circuit 1 comprises solenoid switch valve 3 and solenoid pilot switch valve 4. All the above valves are controlled via an electronic circuit and a first and a second pressure sensors PSl, PS2.
  • first control valves 1 is piloted by first and second control valve pilot lines CVPL1, CVPL2 receiving pressure command signals via a manual user interface, e.g. a joystick. The functioning is the same as that of first control valve 1 in figure 1.
  • Second control valve is piloted by third control valve pilot line CVPL3 and a fourth control valve pilot line CVPL4, such pilot lines being similar to first and second control valve pilot lines CVPL1, CVPL2 and receiving pressure command signals via a manual user interface, e.g. the joystick.
  • Pressure sensors PSl, PS2 are respectively connected to third and fourth control valve pilot lines CVPL3, CVPL4 in order to detect when the user wants to operate the first or the second effect of equipment C, H.
  • Electronic control unit is programmed so as to reproduce the same functioning previously discussed in a for piloting section of figure 1.
  • second control valve 2 switches to second working position PCH2 that vents interconnection I and feeds power line LI .
  • First pressure sensor PSl detects the pressure command signal and, optionally, electronic control unit checks that switch valve 3 is in the correct position, i.e. that venting power line L2. In the negative, provides for electronic actuation so that venting of power line L2 is obtained.
  • electronic control unit is connected to a selector 6 on the dashboard or another location reachable by the user on the driver's seat, that outputs a first signal when a single effect auxiliary equipment is used and a second signal when a double effect auxiliary equipment is used.
  • solenoid switch valve 3 When the electronic control unit receives the first signal, solenoid switch valve 3 is always kept in the position such to vent power line L2 and feed interconnection I regardless that, by mistake, the user inadvertently causes a pressure command on fourth control valve pilot line CVPL4.
  • solenoid switch valve 3 is switched when second pressure sensor PS2 detects a command signal.
  • figure 2 shows a source of hydraulic fluid under pressure comprising a load sensing pump LSP; such source is alternative to the fixed displacement pump unit PI, P2 of figure 1.
  • Load sensing pump LSP is controlled by a load sensing piloting line LSL connected to compensators PC 1 , PC2 to ensure that the pressure drop across control valves 1 , 2 is constant over the operating conditions of the control system. Furthermore, control valves 1, 2 have ports to feed compensators PCI, PC2 and to receive flow from the pressure compensators PCI, PC2 before feeding the relative power line.
  • a first valve PV branches off upstream of fluid lines 1, 2 to direct unnecessary fluid to a tank in order to maintain a pre-set maximum pressure limit at the outlet of load sensing pump LSP.
  • a second valve LSV branches off upstream of both pressure compensators PCI, PC2 to direct unnecessary fluid to a tank in order to maintain a pre-set maximum pressure limit along load sensing piloting line LSL and at the outlet of a load sensing valve of pump LSP.
  • the hydraulic power source of figure 2 or another load sensing layout may be adapted to power also the circuit of figure 1.
  • circuits of figures 1 and 2 are simplified for the purpose of a description focussed on inventive issues.
  • a control circuit embodied in a construction equipment vehicle is more complex and the skilled man is able to introduce the concepts of figures 1 and 2 in a complete power control circuit of a construction vehicle.
  • power actuator B may be a single effect actuator.
  • First and second control valves 1 , 2 may be combined with pilot switch valve 4 and shuttle valve 5 in a single dedicated valve body to be possibly attached to a valve pack of the construction vehicle for the control of other actuators.

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

Abstract

A hydraulic power control circuit for a construction vehicle, having a control section comprising: A first control valve (1) connectable to a source of hydraulic fluid under pressure (P1, P2, LSP) to control a power actuator (B) of the vehicle; A second control valve (2) connectable to the source of hydraulic fluid under pressure (P1, P2, LSP) to control a hydraulic auxiliary equipment (C, H) via a first line (L1) associated to a first effect of the equipment (C, H), the equipment being either a single effect equipment (H) or a double effect equipment (C); An interconnection (I) downstream of the second control valve (1) so that the first and the second control valves (1, 2) are operable to the source of fluid under pressure (P1, P2) so as to control only one effect of the actuator (B) by a flow-summation; A switch valve (3) intercepting the interconnection (I) and a second line (L2) to control the equipment (C, H) in order to control both a single effect and a double effect equipment.

Description

HYDRATJT AC CONTROL CTRCTJTT WTTH FLOW STJMMATTON TN PRESENCE OF
SINGLE OR DOUBLE EFFECT AUXTLTARY EOTJTPMENTS OF A
CONSTRTJCTTON VETTTCLE BACKGROUND OF THE INVENTION
The present invention relates to an hydraulic control circuit for operation of an auxiliary equipment of a construction vehicle, such as a loader, excavator, mini-excavator or the like. In particular the hydraulic circuit controls and powers both a single effect auxiliary equipment, such as a hammer, and a double effect auxiliary equipment, such as a crusher.
A construction vehicle may be provided with a control circuit having a flow summation function for one of its actuators. During flow summation, the flow dedicated to a non-used power line/ power port of control valve is redirected to a preferred actuator in order to increase actuation speed of one effect of the preferred actuator.
For example, in a mini-excavator comprising a boom and an auxiliary attachment for a single effect actuator such as a hammer, when the latter is not used, the flow summation is realized to increase the speed of a boom-up function.
A construction vehicle is often provided with interchangeable auxiliary equipment that may be a single effect hydraulic actuator or a double effect actuator such as a crusher. In particular, a single effect equipment is controlled via a power line connected to a pressure source and a return line directly connected to a tank or to a return line; and a double effect equipment is controlled via a first and a second power line that are selectively connected to a power source and to the sump depending on the controlled effect.
A need is felt to provide an improved hydraulic circuit to control a flow summation function and, at the same time, control a single effect auxiliary equipment and a double effect auxiliary equipment.
SUMMARY OF THE INVENTION
The scope of the present invention is achieved with a hydraulic control circuit according to claim 1.
A construction equipment vehicle may be provided with the control circuit cited above.
Additional features of the invention are comprised in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the present invention, the latter will further be disclosed with reference to the accompanying figures in which:
- figure 1 is a scheme of a simplified control circuit according to the present invention, where only components for the understanding of the invention are shown; and
- figure 2 is a scheme of a simplified control circuit according to a second
embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION
Figure 1 refers, as a whole, to a control circuit 1 for a construction vehicle, e.g. a mini- excavator, comprising a source of pressurized fluid having preferably a first and a second pump PI, P2 each of which is connected, via respective feed lines FL1, FL2, to a control section of the circuit comprising a first and a second control valve 1, 2. Valves PV branch off from feed lines FL1, FL2 to direct unnecessary fluid to a tank in order to maintain a pre-set maximum pressure limit at the outlet of pumps PI , P2.
According to figure 1 , control valve 1 controls an actuator B via a first and a second power line PLA1, PLA2. Each power line PLA1, PLA2 is associated to a respective effect of the actuator so that, when one power line is connected to the source of pressurized fluid to operate an effect of actuator B, the other power line is connected to tank. Actuator B may be either a single or a double effect actuator. In the example, actuator B is a double effect actuator to control a boom of the construction vehicle.
Control valve 2 controls an auxiliary equipment C, H of the construction vehicle via a power line LI that is associated to one effect of the equipment. Control valve 2 is also connected to first power line PLA1 via an interconnection I in order to provide flow- summation to the effect associated to power line PLA1. According to the embodiment of figure 1, flow- summation is associated to a boom-up function.
Control section of circuit 1 also comprises a power line L2 attached to the auxiliary equipment C, H and a switch valve 3 to intercept interconnection I, power line L2 and a return line preferably connected to a tank.
Control circuit 1 also comprises a piloting section comprising hydraulic commands for commutation of control valves 1, 2 and switch valve 3 when a user, via e.g. a joystick or the like, controls actuator B and equipment C, H from a cockpit or driver's seat of the construction vehicle.
According to the embodiment of figure 1 , piloting section comprises a first and a second control valve pilot line CVPL1, CVPL2 to switch first control valve 1 from a neutral and closed position to respective first and second working position PB 1 , PB2 upon manual commands by the user. In particular, first working position PB 1 is associated to a high speed effect of actuator B such as, according to the embodiment of figure 1 , the effect corresponding to boom-up.
In order to provide flow summation for the high speed effect when equipment C, H is not in use, piloting section also comprises a pilot switch valve 4 having a first input receiving a pressure command from first control valve pilot line CVPL 1 via a T-branch Tl, and a second input receiving a pressure command for equipment C, H. Output of pilot switch valve 4 is such to switch second control valve 2 from a neutral and closed position to a first working position PCH1 to feed interconnection I. Second control valve 2 has a second working PCH2 position to feed a first effect of equipment C, H via first power line LI . Switch to such second working position of second control valve 2 is piloted via a third control valve pilot line CVPL3.
In a neutral position, pilot switch valve 4 is such to enable the switch of second control valve 2 to feed interconnection I when a user pressurizes first control valve pilot line CVPL1 to provide flow summation for the first effect of actuator B. In such a condition, switch valve 3 as well is a neutral position such that interconnection I feeds power line PLA1 of actuator B. Furthermore, pilot switch valve 4 may switch to a further position where flow summation is excluded and first working position PCH1 of second control valve 2 is reached when equipment C is a double effect equipment and the user commands a second effect of equipment C, e.g. a crusher. It is worth noting that the first effect of equipment C, H via power line LI is associated to second working position PCH2 of second control valve 2 via third control valve pilot line CVPL3.
Pilot switch valve 4 switches from neutral position to the further position via a shuttle valve 5 that outputs the higher pressure signal between third control valve pilot line CVPL3 and a user's command for the second effect of equipment C when the latter is a double-effect actuator. In particular, shuttle valve 5 receives the signal from third control valve pilot line CVPL3 via a first pilot line PL1 and the signal for the second effect of equipment C via a second pilot line PL2.
Piloting section also comprises a junction Jl where second pilot line PL2 meets a third pilot line PL3 to switch valve 3. Junction Jl is also connected to second input of pilot switch valve 4 and to the user's command for the second effect of equipment C.
According to a preferred embodiment of the present invention, user's command of equipment's second effect is controlled via a selector valve 6. The latter has a first stable position that pressurizes junction Jl so that both second pilot line PL2 and third pilot line PL3 cause commutation of pilot switch valve 4 and switch valve 3 respectively. This enables the second effect of equipment C.
Selector valve 6 has a second stable position to vent junction Jl . Accordingly, switch valve 3 and pilot switch valve 4 are kept by respective springs in the configuration such to provide flow-summation.
In use, first control valve 1 is switched by the user acting on e.g. a joystick to provide alternate pressure commands on first and second control valve pilot lines CVPL1, CVPL2 to respectively activate actuator B first effect, i.e. high speed effect, and second effect, where available. According to the embodiment of figure 1, high speed effect corresponds to 'boom- up' function.
Upon command signal via first control valve pilot line CVPL1, second control valve 2 is switched to first working position PCH1 via T-junction Tl in order to provide flow- summation to the high speed effect of actuator B, i.e. flow across second control valve 2, i.e. a proportional valve, is directed to power line PLA1 via interconnection I. Flow-summation is possible only when equipment C, H is not actuated by the operator.
Indeed, when operator commands the first effect of equipment C, H via third control valve pilot line CVPL3, second control valve 2 switches to second working position PCH2 that vents interconnection I and feeds power line LI . When first effect of equipment C, H is actuated, power line L2 is vented via switch valve 3. In order to avoid back flow towards second control valve 2 a check valve 7 is provided between power line PL1 and second control valve 2. According to the embodiment of figure 1, check valve 7 is along
interconnection I.
Equipment C, H is detachable from power lines LI, L2 depending on the use of the vehicle. In order to safely provide the correct set of commands for a single effect auxiliary equipment, such as a hammer, and a double effect auxiliary equipment, such a crusher, the user selects the stable position of selector valve 6, which can be a bi-stable lever or button on a dashboard of the vehicle or the joystick.
In particular, the position of selector valve 6 such that junction Jl is vented, inhibits any feed to power line L2 and, thus, the second effect of the equipment. Therefore the user sets selector valve 6 to stably vent junction Jl when a single effect equipment such as a hammer is attached to the construction vehicle.
The user sets selector valve 6 to pressurize junction Jl in order to commute pilot switch valve 4 and switch valve 3 and thus, respectively, associate the command for the second effect of the equipment and the switch to the first working position PCH1 of second control valve 2. Accordingly, interconnection I is closed and flow reaches power line L2 via the further position of switch control valve 3. In particular, junction Jl splits a single command signal for the second effect of equipment C to affect both pilot switch valve 4 and switch valve 3.
Advantages of the control circuit according to the present invention are as follows.
Via switch valve 3 it is possible to add a further degree of flexibility so as to control at the same time flow summation for a first actuator and both a single and a double effect auxiliary equipment.
When control section is piloted by pressure command signals via the piloting section, the provision of shuttle valve 5 provides for the use of a single component, i.e. pilot switch valve 4, to select the correct command signal to enable/disable actuation of the second effect of the auxiliary equipment.
Furthermore, selector valve 6 safely ensures that commands are properly associated to a single effect auxiliary equipment or a double effect auxiliary equipment.
Junction Jl efficiently splits the command signal to reach both pilot switch valve 4 and switch valve 3. The same applies to pilot line PL1 branching from third control valve pilot line CVPL3.
It is possible that changes and variations are made to the control circuit according to the present invention without departing from the scope of protection as defined by the attached claims.
In particular, actuator may be an actuator of a further auxiliary equipment enjoying a flow- summation function. Actuator B and the further auxiliary equipment can be both single or double effect.
It is also possible to provide an existing control circuit having a flow summation with the hydraulic elements to obtain control of an auxiliary equipment either of the single or of the double effect type.
To do so, as a first step, switch valve 3 shall be provided having a first position to intercept interconnection I and to vent power line L2 and a second position to close interconnection I and connect power line L2 to a source of pressurized fluid.
A further step is to provide, within a piloting section, the shuttle valve 5.
An even further step is to provide, within the piloting section, the selector valve 6.
According to a further alternative, shown in figure 2, control circuit 1 comprises solenoid switch valve 3 and solenoid pilot switch valve 4. All the above valves are controlled via an electronic circuit and a first and a second pressure sensors PSl, PS2. In such an embodiment, first control valves 1 is piloted by first and second control valve pilot lines CVPL1, CVPL2 receiving pressure command signals via a manual user interface, e.g. a joystick. The functioning is the same as that of first control valve 1 in figure 1.
Second control valve is piloted by third control valve pilot line CVPL3 and a fourth control valve pilot line CVPL4, such pilot lines being similar to first and second control valve pilot lines CVPL1, CVPL2 and receiving pressure command signals via a manual user interface, e.g. the joystick.
Pressure sensors PSl, PS2 are respectively connected to third and fourth control valve pilot lines CVPL3, CVPL4 in order to detect when the user wants to operate the first or the second effect of equipment C, H.
Electronic control unit is programmed so as to reproduce the same functioning previously discussed in a for piloting section of figure 1. In particular, when the user commands the first effect of equipment C, H via third control valve pilot line CVPL3, second control valve 2 switches to second working position PCH2 that vents interconnection I and feeds power line LI . First pressure sensor PSl detects the pressure command signal and, optionally, electronic control unit checks that switch valve 3 is in the correct position, i.e. that venting power line L2. In the negative, provides for electronic actuation so that venting of power line L2 is obtained.
When the user commands fourth control valve pilot line CVPL4, pressure sensor PS2 detects the pressure signal, consequently, electronic control unit switches solenoid pilot switch valve 4 to exclude flow- summation and solenoid switch valve 3 to feed power line L2.
Optionally, in order to safely switch between a single effect auxiliary equipment or a double effect auxiliary equipment, electronic control unit is connected to a selector 6 on the dashboard or another location reachable by the user on the driver's seat, that outputs a first signal when a single effect auxiliary equipment is used and a second signal when a double effect auxiliary equipment is used. When the electronic control unit receives the first signal, solenoid switch valve 3 is always kept in the position such to vent power line L2 and feed interconnection I regardless that, by mistake, the user inadvertently causes a pressure command on fourth control valve pilot line CVPL4. When electronic selector 6 provides to the electronic control unit the second signal, solenoid switch valve 3 is switched when second pressure sensor PS2 detects a command signal.
Furthermore, figure 2 shows a source of hydraulic fluid under pressure comprising a load sensing pump LSP; such source is alternative to the fixed displacement pump unit PI, P2 of figure 1.
Load sensing pump LSP is controlled by a load sensing piloting line LSL connected to compensators PC 1 , PC2 to ensure that the pressure drop across control valves 1 , 2 is constant over the operating conditions of the control system. Furthermore, control valves 1, 2 have ports to feed compensators PCI, PC2 and to receive flow from the pressure compensators PCI, PC2 before feeding the relative power line.
Furthermore, a first valve PV branches off upstream of fluid lines 1, 2 to direct unnecessary fluid to a tank in order to maintain a pre-set maximum pressure limit at the outlet of load sensing pump LSP. Accordingly, a second valve LSV branches off upstream of both pressure compensators PCI, PC2 to direct unnecessary fluid to a tank in order to maintain a pre-set maximum pressure limit along load sensing piloting line LSL and at the outlet of a load sensing valve of pump LSP.
The hydraulic power source of figure 2 or another load sensing layout may be adapted to power also the circuit of figure 1.
The circuits of figures 1 and 2 are simplified for the purpose of a description focussed on inventive issues. A control circuit embodied in a construction equipment vehicle is more complex and the skilled man is able to introduce the concepts of figures 1 and 2 in a complete power control circuit of a construction vehicle.
Furthermore, depending on the layout and use of the construction vehicle, power actuator B may be a single effect actuator.
First and second control valves 1 , 2 may be combined with pilot switch valve 4 and shuttle valve 5 in a single dedicated valve body to be possibly attached to a valve pack of the construction vehicle for the control of other actuators.

Claims

CLAIMS:
1. A hydraulic power control circuit for a construction vehicle, having a control section comprising:
A first control valve (1) connectable to a source of hydraulic fluid under pressure (PI,
P2, LSP) to control a power actuator (B) of the vehicle;
A second control valve (2) connectable to the source of hydraulic fluid under pressure (PI, P2, LSP) to control a hydraulic auxiliary equipment (C, H) via a first line (LI) associated to a first effect of the equipment (C, H), the equipment being either a single effect equipment (H) or a double effect equipment (C);
An interconnection (I) downstream of the second control valve (1) so that the first and the second control valves (1, 2) are operable, when both switched from the neutral position, to connect the actuator (B) to the source of fluid under pressure (PI, P2, LSP) so as to control only one effect of the actuator (B) by a flow- summation of the flow from the first and the second control valve (1, 2);
A switch valve (3) intercepting the interconnection (I) and a second line (L2) to control the equipment (C, H);
Wherein the switch valve (3) is operable either to discharge the second line (L2) for operation of the equipment (H) in a single effect mode and feed of the actuator (B) via the interconnection (I); or to feed the second line (L2) via the second control valve (2) and the source of fluid under pressure (PI, P2, LSP) for operation of a second effect of the equipment (C) in a double effect mode.
2. The control circuit of claim 1, wherein a piloting section is provided to switch the switch valve (3) and the first and the second control valves (1, 2) based on user's hydraulic command signals, the piloting section comprising a pilot switch valve (4) operable in:
a first position to simultaneously switch the first and the second control valves (1, 2) such as to feed the only one effect of the actuator (B) by the source of fluid under pressure (PI, P2, LSP) via the interconnection (I); and
a second position where the first and the second control valves (1, 2) are
independently switchable one from the other to independently control the actuator (B) and the equipment (C, H); the pilot switch valve (4) being switched in the second position by a shuttle valve (5) either upon receiving a first hydraulic command signal for actuation of the first effect of the equipment (C) from a first piloting line (PL1) or upon receiving a second hydraulic command signal for actuation of the second effect of the equipment (C) from a second piloting line (PL2), the second hydraulic command signal being transmitted to the switch valve (4) via a junction (Jl) of the piloting section so as to cause the feed of the second line (L2) by the source of fluid under pressure (P2).
3. The control circuit according to claim 2, wherein the piloting section comprises a selector valve (6) manually operable by the user either to drain the second piloting line (PL2) and a third piloting line (PL3) of the switch valve (3) so that the second line (L2) is connected to a tank (T) and control of the single effect equipment (H) is enabled and control of the second effect of the equipment (C) via the second line (L2) is disabled; or to pressurize the second piloting line (PL2) so that control of the double effect equipment (C) is enabled.
4. The control circuit according to claims 2 or 3, wherein the junction (Jl) splits a command pressure signal to pilot the shuttle valve (5) and the switch valve (3).
5. The control circuit according to claim 1, wherein a piloting section is provided to switch the first and the second control valves (1, 2) based on user's hydraulic command signals, the piloting section comprising a solenoid pilot switch valve (4) operable in:
a first position to simultaneously switch the first and the second control valves (1, 2) such as to feed only one effect of the double effect actuator (B) by the first and the second source of fluid under pressure (PI, P2) via the interconnection (I); and
a second position where the first and the second control valves (1, 2) are
independently switchable one from the other;
the solenoid pilot switch valve being operated on the basis of electric or electronic outputs of a first and a second pressure sensor (PS1, PS2) detecting the hydraulic pressure command signals associated to the first or the second effect of the equipment (C, H) via the second control valve (2).
6. The control circuit according to claim 5, wherein a selector (6) providing electric or electronic signals is manually operable by the user either to inhibit the switch of the solenoid switch valve (3) when in a single-effect equipment mode; or to enable the switch of the solenoid switch valve (3) when in a double-effect equipment mode.
7. The control circuit according to any of the preceding claims, wherein the source of pressurized fluid comprises a first source (PI) to feed the first control valve (1) and a second source (P2) to feed the second control valve (2).
8. Construction vehicle comprising a control circuit according to any of the preceding claims and wherein the fluid-summation is provided for an actuator being either a single or a double effect actuator.
9. Method to retrofit a construction vehicle with a power control circuit having a control section comprising:
A first control valve (1) connectable to a source of hydraulic fluid under pressure (PI,
P2, LSP) to control a power actuator (B);
A second control valve (2) connectable to the source of hydraulic fluid under pressure
(PI, P2, LSP) to control a hydraulic equipment (C, H) via a first line (LI), the hydraulic equipment being either a single effect equipment (H) or a double effect equipment (C);
An interconnection (I) downstream of the second control valve (1) so that the first and the second control valves (1, 2) are operable, when switched from the neutral position, to connect the double effect actuator (B) to the source of fluid under pressure (PI, P2, LSP) so as to control only one effect of the double effect actuator (B) by the flow of the source of fluid under pressure (PI, P2);
Comprising the step of:
- providing a switch valve (3) intercepting the interconnection (I) and a second line (L2) to control the power equipment (C, H);
Wherein the switch valve (3) is operable either to discharge the second line (L2) for operation of the power equipment (H) in a single effect mode and feed of the double effect actuator (B) via the interconnection (I); or to close the interconnection (I) and feed the second line (L2) via the second control valve (2) and the source of fluid under pressure (PI, P2) for operation of the power equipment (C) in a double effect mode; - providing a pilot switch valve (4) operable in:
a first position to simultaneously switch the first and the second control valves (1, 2) such as to feed the only one effect of the actuator (B) by the source of fluid under pressure (PI, P2) via the interconnection (I); and
a second position where the first and the second control valves (1, 2) are
independently switchable one from the other to independently control the actuator (B) and the equipment (C, H);
- providing a shuttle valve (5) connected to switch the pilot switch valve (4) in the second position either upon receiving a first hydraulic command signal for actuation of the first effect of the equipment (C) from a first piloting line (PL1) or upon receiving a second hydraulic command signal for actuation of the second effect of the equipment (C) from a second piloting line (PL2), the second hydraulic command signal being transmitted to the switch valve (4) via a junction (Jl) of the piloting section so as to cause the feed of the second line (L2) by the source of fluid under pressure (P2);
- providing a selector valve (6) manually operable by the user either to drain the second piloting line (PL2) and a third piloting line (PL3) of the switch valve (3) so that the second line (L2) is connected to a tank (T) and control of the single effect equipment (H) is enabled and control of the second effect of the equipment (C) via the second line (L2) is disabled; or to pressurize the second piloting line (PL2) so that control of the double effect equipment (C) is enabled.
EP18711324.6A 2017-03-15 2018-03-14 Hydraulic control circuit with flow summation in presence of single or double effect auxiliary equipments of a construction vehicle Active EP3595847B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT102017000028841A IT201700028841A1 (en) 2017-03-15 2017-03-15 HYDRAULIC CONTROL CIRCUIT WITH SUMMARY OF FLOW RATES IN THE PRESENCE OF AUXILIARY SINGLE OR DOUBLE-EFFECT TOOLS FOR A CONSTRUCTION VEHICLE
PCT/EP2018/056367 WO2018167135A1 (en) 2017-03-15 2018-03-14 Hydraulic control circuit with flow summation in presence of single or double effect auxiliary equipments of a construction vehicle

Publications (2)

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EP3595847A1 true EP3595847A1 (en) 2020-01-22
EP3595847B1 EP3595847B1 (en) 2021-05-12

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IT (1) IT201700028841A1 (en)
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Publication number Priority date Publication date Assignee Title
JPS57195904A (en) * 1981-05-26 1982-12-01 Shimadzu Corp Hydraulic cylinder system
JP2579587Y2 (en) * 1993-12-27 1998-08-27 新キャタピラー三菱株式会社 Hydraulic circuit of construction machinery
US8919114B2 (en) * 2011-10-21 2014-12-30 Caterpillar Inc. Closed-loop hydraulic system having priority-based sharing

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IT201700028841A1 (en) 2018-09-15
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