EP1553308A1 - Electrohydraulic actuation system - Google Patents
Electrohydraulic actuation system Download PDFInfo
- Publication number
- EP1553308A1 EP1553308A1 EP03741367A EP03741367A EP1553308A1 EP 1553308 A1 EP1553308 A1 EP 1553308A1 EP 03741367 A EP03741367 A EP 03741367A EP 03741367 A EP03741367 A EP 03741367A EP 1553308 A1 EP1553308 A1 EP 1553308A1
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- EP
- European Patent Office
- Prior art keywords
- port
- hydraulic
- pressure
- electro
- working fluid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- 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
- F15B9/00—Servomotors with follow-up action, e.g. obtained by feed-back control, i.e. in which the position of the actuated member conforms with that of the controlling member
- F15B9/14—Servomotors with follow-up action, e.g. obtained by feed-back control, i.e. in which the position of the actuated member conforms with that of the controlling member with rotary servomotors
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- 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
- F15B11/161—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
- F15B11/163—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for sharing the pump output equally amongst users or groups of users, e.g. using anti-saturation, pressure compensation
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- 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
- F15B11/161—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
- F15B11/165—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for adjusting the pump output or bypass in response to demand
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- 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
- F15B11/22—Synchronisation of the movement of two or more servomotors
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- 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
- F15B9/00—Servomotors with follow-up action, e.g. obtained by feed-back control, i.e. in which the position of the actuated member conforms with that of the controlling member
- F15B9/16—Systems essentially having two or more interacting servomotors, e.g. multi-stage
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- 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
- F15B2211/20553—Type of pump variable capacity with pilot circuit, e.g. for controlling a swash plate
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- 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
- F15B2211/3052—Shuttle valves
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- 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
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- 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
- F15B2211/30535—In combination with a pressure compensating valve the pressure compensating valve is arranged between pressure source and directional control valve
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- 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
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- 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
- F15B2211/31—Directional control characterised by the positions of the valve element
- F15B2211/3105—Neutral or centre positions
- F15B2211/3111—Neutral or centre positions the pump port being closed in the centre position, e.g. so-called closed centre
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- 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
- F15B2211/31—Directional control characterised by the positions of the valve element
- F15B2211/3144—Directional control characterised by the positions of the valve element the positions being continuously variable, e.g. as realised by proportional valves
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- 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
- F15B2211/315—Directional control characterised by the connections of the valve or valves in the circuit
- F15B2211/3157—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line
- F15B2211/31576—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line having a single pressure source and a single output member
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- 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
- F15B2211/321—Directional control characterised by the type of actuation mechanically
- F15B2211/324—Directional control characterised by the type of actuation mechanically manually, e.g. by using a lever or pedal
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- 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
- F15B2211/321—Directional control characterised by the type of actuation mechanically
- F15B2211/325—Directional control characterised by the type of actuation mechanically actuated by an output member of the circuit
- F15B2211/326—Directional control characterised by the type of actuation mechanically actuated by an output member of the circuit with follow-up action
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- 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
- F15B2211/327—Directional control characterised by the type of actuation electrically or electronically
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- 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
- F15B2211/355—Pilot pressure control
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- 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
- F15B2211/50—Pressure control
- F15B2211/505—Pressure control characterised by the type of pressure control means
- F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
- F15B2211/50518—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using pressure relief valves
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- 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
- F15B2211/50—Pressure control
- F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
- F15B2211/5151—Pressure control characterised by the connections of the pressure control means in the circuit being connected to a pressure source and a directional control valve
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- 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
- F15B2211/50—Pressure control
- F15B2211/57—Control of a differential pressure
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- 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
- F15B2211/605—Load sensing circuits
- F15B2211/6051—Load sensing circuits having valve means between output member and the load sensing circuit
- F15B2211/6054—Load sensing circuits having valve means between output member and the load sensing circuit using shuttle valves
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- 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
- F15B2211/605—Load sensing circuits
- F15B2211/6051—Load sensing circuits having valve means between output member and the load sensing circuit
- F15B2211/6057—Load sensing circuits having valve means between output member and the load sensing circuit using directional control valves
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- 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
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- 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
- F15B2211/665—Methods of control using electronic components
- F15B2211/6654—Flow rate control
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- 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
- F15B2211/665—Methods of control using electronic components
- F15B2211/6656—Closed loop control, i.e. control using feedback
Definitions
- the hydraulic actuation system 900 includes a variable displacement hydraulic pump 911 for discharging a working fluid, a tank 912 from which the working fluid is discharged and a relief valve 913 for keeping the working fluid discharge pressure of the variable displacement hydraulic pump 911 at a predetermined set pressure or lower.
- the hydraulic actuation system 900 includes a unit 920 having reduction gears 921 connected to a load, not shown, a variable displacement hydraulic motor 922 for imparting a driving force to the reduction gears 921, an operation lever 923 adapted to be operated by an operator, a manual direction control valve 924 for changing the communication of the variable displacement hydraulic pump 911 and the tank 912 with the variable displacement hydraulic motor 922 in accordance with the operation amount of the operation lever 923 and an automatic two-position valve 925 for cutting off the communication of the variable displacement hydraulic pump 911 and the tank 912 with the variable displacement hydraulic motor 922 in accordance with the operation amount of the operation lever 923 when the communication of the variable displacement hydraulic pump 911 and the tank 912 with the variable displacement hydraulic motor 922 in accordance with the operation amount of the operation lever 923 is cut off by the manual direction control valve 924.
- the hydraulic actuation system 900 includes a unit 930 having a similar configuration to that of the unit 920, while the detailed description of the unit 930 is omitted here.
- the hydraulic actuation system 900 includes a selector valve 941 for selecting a working fluid having a greater pressure of a working fluid supplied from the variable displacement hydraulic pump 911 to the variable displacement hydraulic motor 922 of the unit 920 and a working fluid supplied to the variable displacement hydraulic pump 911 to a variable displacement hydraulic motor 932 of the unit 930, a two-position electromagnetic valve 942 for allowing the working fluid discharged by the variable displacement hydraulic pump 911 to pass when a pressure resulting from adding a predetermined set pressure to the pressure of the working fluid selected by the selector valve 941 is greater than the working fluid discharge pressure of the variable displacement hydraulic pump 911 discharges the working fluid, a discharge volume changing hydraulic cylinder 943 for changing the discharge volume of the variable displacement hydraulic pump 911 based on the pressure of the working fluid which is allowed to pass by the two-position electromagnetic valve 942 and the working fluid discharge pressure of the variable displacement hydraulic pump 911.
- variable displacement hydraulic pump 911 when the working fluid discharge volume of the variable displacement hydraulic pump 911 becomes smaller than a total amount of working fluid needed to be supplied to the variable displacement hydraulic motor 922 of the unit 920 and the variable displacement hydraulic motor 932 of the unit 930, the working fluid discharged by the variable displacement hydraulic pump 911 flows to the variable displacement hydraulic motor having a smaller load pressure in preference to the other.
- variable displacement hydraulic motor 922 of the unit 920 and the variable displacement hydraulic motor 932 of the unit 930 there occurs a shortage in volume of the working fluid supplied to the variable displacement hydraulic motor having a larger load pressure of the variable displacement hydraulic motor 922 of the unit 920 and the variable displacement hydraulic motor 932 of the unit 930, and the output thereof is reduced when compared with a case where there occurs no shortage in volume of the working fluid supplied thereto.
- an object of the invention is to provide an electro-hydraulic actuation system which can prevent the generation of a shortage in volume of a fluid supplied to a hydraulic actuator having a larger load pressure of hydraulic actuators of a plurality of electro-hydraulic actuators.
- an electro-hydraulic actuation system including a pump, a plurality of electro-hydraulic actuators each having an electric motor, a hydraulic actuator and a fluid volume changing valve for changing the volume of a fluid discharged by the pump based on driving amounts of the electric motor and the hydraulic actuator for supply to the hydraulic actuator, a discharge volume changing means for changing the volume of the fluid discharged by the pump based on a maximum pressure of pressures of the fluid supplied to the hydraulic actuators of the plurality of electro-hydraulic actuators and the discharge pressure of the fluid discharged by the pump and a rotational speed changing means for changing the rotational speed of the electric motors of the plurality of electro-hydraulic actuators at substantially the same ratio relative to the electric motors of the plurality of electro-hydraulic actuators based on a maximum pressure of pressures of the fluid supplied to the hydraulic actuators of the plurality of electro-hydraulic actuators and the discharge pressure of the fluid discharged by the pump.
- the electro-hydraulic actuation system of the invention can reduce the volume of the fluid supplied to the hydraulic actuators of the plurality of electro-hydraulic actuators at substantially the same ratio when there occurs a shortage in volume of the fluid supplied to the hydraulic actuators of the plurality of electro-hydraulic actuators, it is possible to prevent the occurrence of a shortage in volume of the fluid supplied to the actuator having a larger load pressure of the hydraulic actuators of the plurality of electro-hydraulic actuators.
- an electro-hydraulic actuation system 100 as an electro-hydraulic actuation system according to the first embodiment includes a variable displacement hydraulic pump 111 as a pump of a constant horse power for discharging a working fluid (fluid), a tank 112 from which the working fluid is discharged and a relief valve 113 for keeping the working fluid discharge pressure of the variable displacement hydraulic pump 111 at a predetermined set pressure or lower.
- the electro-hydraulic actuation system 100 includes a unit (refer to Figs. 4 to 7) as an electro-hydraulic actuator having reduction gears 121 connected to a load not shown, a hydraulic motor 122 as a hydraulic actuator having formed therein a port 122a and a port 122b which are made to communicate with the variable displacement hydraulic pump 111 or the tank 112 and adapted to impart a driving force to the reduction gears 121 by virtue of the pressure of a working fluid supplied to the port 122a and the port 122b, an electric motor 123 driven in accordance with an electric signal entered, a first toothed shaft 124 adapted to rotate together with a driving shaft of the hydraulic motor 122 and a second toothed shaft 125 which is brought into a screw connection with a rotating shaft of the electric motor 123 and is brought into a mesh engagement with the first toothed shaft 124.
- a unit (refer to Figs. 4 to 7) as an electro-hydraulic actuator having reduction gears 121 connected
- the hydraulic motor 122 has, as shown in Figs. 4 to 7, a box body 151 to which the electric motor 123 is fixed, a box body 152 fixed to the box body 151, a swash plate 153 fixed in the interior of the box body 152, a motor shaft 154 connected to the reduction gears 121 at one end and brought into engagement with the first toothed shaft 124 at the other end thereof in such a manner as to rotate in synchronism with the first toothed shaft 124, a bearing 155 and a bearing 156 which rotatably support the motor shaft 154 on the box body 151 and the box body 152, respectively, a cylinder block into which the motor shaft 154 is inserted at the center thereof, in which a plurality of cylinder chambers 157a are formed and which is in engagement with the motor shaft 154 in such a manner as to rotate in synchronism with the motor shaft 154, a plurality of pistons 158 accommodated in the cylinder chambers 157a in the cylinder block
- the unit 120 has, as shown in Figs. 1 to 3, an electro-hydraulic servo valve 127 as a fluid volume changing valve having formed therein a port 127a communicating with the variable displacement hydraulic pump 111, a port 127b communicating with the tank 112, a port 127c communicating with the port 122a of the hydraulic motor 122, a port 127d communicating with the port 122b of the hydraulic motor 122 and a port 127e, adapted to take any of a first position 127A, a second position 127B and a third position 127C based on the rotating amount of the second toothed shaft 125 and the driving amount of the electric motor 123 and adapted to change the volume of a working fluid discharged by the variable displacement hydraulic pump 111 for supply to the hydraulic motor 122.
- an electro-hydraulic servo valve 127 as a fluid volume changing valve having formed therein a port 127a communicating with the variable displacement hydraulic pump 111, a port 127b communicating with the tank 112, a port
- the first position 127A is a position where the port 127a is made to communicate with the port 127c and the port 127e, and the port 127b is made to communicate with the port 127d
- the second position 127B is a position where the communication between the port 127a, port 127c and port 127d is cut off, while the port 127b is made to communicate with the port 127e
- the third position 127C is a position where the communication between the port 127a, port 127d and port 127e is established, and the port 127b is made to communicate with the port 127c.
- the unit 120 has, as shown in Figs. 1 to 3, a check valve 128a (refer to Fig. 5) disposed between the variable displacement hydraulic pump 111 and the port 127a of the electro-hydraulic servo valve 127 for preventing the passage of a working fluid from the port 127a of the electro-hydraulic servo valve 127 to the variable discharge volume hydraulic valve 111, a check valve 128b (refer to Figs.
- the electro-hydraulic actuation system 100 has a unit 130 having a similar configuration to that of the unit 120.
- the electro-hydraulic actuation system 100 includes a two-position valve 142 having formed therein a port 142a which communicates with the tank 112, a port 142b and a port 142c which communicate with the variable displacement hydraulic pump 111, a port 142d which communicates with the port 141c of the selector valve 141 via a throttle valve 140a and a port 142e and adapted to take either of a first position 142A where the port 142a and the port 142e are made to communicate with each other in accordance with the pressure of a working fluid supplied to the port 142c and the port 142e and a second position 142B where the port 142b and the port 142e are made to communicate with each other.
- the electro-hydraulic actuation system 100 includes a spring 143 for biasing the two-position valve 142 so that the two-position valve 142 takes the first position 142A when the pressure of a working fluid supplied to the port 142c of the two-position valve 142 is equal to or lower than a pressure resulting from adding a predetermined set pressure to the pressure of a working fluid supplied to the port 142d of the two-position valve 142.
- the electro-hydraulic actuation system 100 includes a discharge volume changing hydraulic cylinder 144 having formed therein a cylinder chamber 144a which communicates with the port 142e of the two-position valve 142 via a throttle valve 140b and a cylinder chamber 144b which communicates with the variable displacement hydraulic pump 111, connected with the variable displacement hydraulic pump 111 in such a manner to increase the discharge volume of the variable displacement hydraulic pump 111 when retracted than extended and adapted to be extended when the pressure of a working fluid within the cylinder chamber 144a is equal to or greater than the pressure of a working fluid within the cylinder chamber 144b and to be retracted when the pressure of the working fluid within the cylinder chamber 144a is smaller than the pressure of the working fluid within the cylinder chamber 144b.
- the electro-hydraulic servo valve 127 of the unit 120, the electro-hydraulic servo valve 137 of the unit 130, the selector valve 141, the two-position valve 142, the spring 143 and the discharge volume changing hydraulic cylinder 144 constitutes a discharge volume changing means for changing the discharge pressure of a working fluid discharged by the variable displacement hydraulic pump 111 based on a maximum pressure of pressures of the working fluid supplied to the hydraulic motor 122 of the unit 120 and the hydraulic motor 132 of the unit 130 and the discharge pressure of the working fluid discharged by the variable displacement hydraulic pump 111.
- the electro-hydraulic actuation system 100 includes a pressure gauge 145 for detecting the pressure of a working fluid supplied to the port 122a of the hydraulic motor 122 of the unit 120, a pressure gauge 146 for detecting the pressure of a working fluid supplied to the port 122b of the hydraulic motor 122, a pressure gauge 147 for detecting the pressure of a working fluid supplied to the port 132a of the hydraulic motor 132 of the unit 130, a pressure gauge 148 for detecting the pressure of a working fluid supplied to the port 132b of the hydraulic motor 132, a pressure gauge 149 for detecting the working fluid discharge pressure of the variable displacement hydraulic pump 111 and a computer, not shown, to which pressures detected by the pressure gauge 145, the pressure gauge 146, the pressure gauge 147, the pressure gauge 148 and the pressure gauge 149 are inputted for changing the rotation speed of the electric motor 123 of the unit 120 and the electric motor 133 of the unit 130 based on the pressures so inputted at substantially the same ratio relative to the electric motor
- the ration at which the rotational speed of the electric motor 123 and the electric motor 133 may be a constant value at all times or a value which changes in accordance with pressures detected by the pressure gauge 145, the pressure gauge 146, the pressure gauge 147, the pressure gauge 148 and the pressure gauge 149.
- the selector valve 141 selects a greater pressure of the load pressure of the hydraulic motor 122 of the unit 120 and the load pressure of the hydraulic motor 132 of the unit 130, the pressure of the working fluid supplied to the port 142d of the two-position valve 142 which communicates with the port 141c of the selector valve 141 via the throttle 140a becomes the larger pressure of the load pressures of the hydraulic motor 122 and the hydraulic motor 132.
- the port 142c of the two-position valve 142 communicates with the variable displacement hydraulic pump 111, the pressure of the working fluid supplied to the port 142c of the two-position valve 142 becomes the working fluid discharge pressure of the variable displacement hydraulic pump 111.
- the two-position valve 142 takes the first position 142A where the port 142a which communicates with the tank 112 is made to communicate with the port 142e when the working fluid discharge pressure of the variable displacement hydraulic pump 111 becomes equal to or smaller than the pressure resulting from adding the predetermined set pressure by the spring 143 to the greater pressure of the load pressures of the hydraulic motor 122 and the hydraulic motor 132.
- the pressure of the working fluid within the cylinder chamber 144b of the discharge volume changing hydraulic cylinder 144 which communicates with the variable displacement hydraulic pump 111 is the working fluid discharge pressure of the variable displacement hydraulic pump 111
- the pressure of the working fluid within the cylinder chamber 144a becomes smaller than the pressure of the working fluid within the cylinder chamber 144b, whereby the discharge volume changing hydraulic cylinder 144 retracts to thereby increase the discharge volume of the variable displacement hydraulic pump 111.
- the two-position valve 142 takes the second position 142B where the port 142b which communicates with the variable displacement hydraulic pump 111 is made to communicate with the port 142e when the working fluid discharge pressure of the variable displacement hydraulic pump 111 becomes greater than the pressure resulting from adding the predetermined set pressure by the spring 143 to the greater pressure of the load pressures of the hydraulic motor 122 of the unit 120 and the hydraulic motor 132 of the unit 130.
- the pressure of the working fluid within the cylinder chamber 144b of the discharge volume changing hydraulic cylinder 144 is the working fluid discharge pressure of the variable displacement hydraulic pump 111
- the pressure of the working fluid within the cylinder chamber 144a becomes equal to or greater than the pressure of the working fluid within the cylinder chamber 144b, whereby the discharge volume changing hydraulic cylinder 144 extends to thereby decrease the discharge volume of the variable displacement hydraulic pump 111.
- the electro-hydraulic actuation system 100 changes the working fluid discharge volume of the variable displacement hydraulic pump 111 so that a differential pressure between the greater pressure of the load pressures of the hydraulic motor 122 of the unit 120 and the hydraulic motor 132 of the unit 130 and the working fluid discharge pressure of the variable displacement hydraulic pump 111 becomes the predetermined set pressure by the spring 143.
- a smallest pressure (hereinafter, referred to as a minimum differential pressure) of a differential pressure between a pressure detected by the pressure gauge 149 and a pressure detected by the pressure gauge 145, a differential pressure between the pressure detected by the pressure gauge 149 and a pressure detected by the pressure gauge 146, a differential pressure between the pressure detected by the pressure gauge 149 and a pressure detected by the pressure gauge 147, and a differential pressure between the pressure detected by the pressure gauge 149 and a pressure detected by the pressure gauge 148 becomes the predetermined set pressure by the spring 143.
- the pressure detected by the pressure gauge 149 or the working fluid discharge pressure of the variable displacement hydraulic pump 111 decreases, the minimum differential pressure becomes smaller than the predetermined set pressure by the spring 143.
- the computer can determine whether or not there occurs a shortage in volume of the working fluid supplied to either of the hydraulic motor 122 of the unit 120 and the hydraulic motor 132 of the unit 130.
- the computer determines that there occurs a shortage in volume of the working fluid supplied to either of the hydraulic motor 122 of the unit 120 and the hydraulic motor 132 of the unit 130 and then decreases the rotational speed of the electric motor 123 of the unit 120 and the electric motor 133 of the unit 130 at substantially the same ratio relative to the electric motor 123 and the electric motor 133.
- the electro-hydraulic actuation system 100 can decrease the volume of the working fluid supplied to the hydraulic motor 122 of the unit 120 and the hydraulic motor 132 of the unit 130 at substantially the same ratio when there occurs a shortage in volume of working fluid supplied to the hydraulic motor 122 of the unit 120 and the hydraulic motor 132 of the unit 130, the occurrence of a shortage in volume of working fluid supplied to the hydraulic motor having a larger load pressure of the hydraulic motor 122 of the unit 120 and the hydraulic motor 132 of the unit 130 can be prevented.
- the electro-hydraulic actuation system 100 can decrease the volume of the working fluid supplied to the hydraulic motor 122 of the unit 120 and the hydraulic motor 132 of the unit 130 at substantially the same ratio, for example, in a case where the hydraulic motor 122 of the unit 120 is used for a right side caterpillar of a hydraulic shovel and the hydraulic motor 132 of the unit 130 is used for a left side caterpillar of the hydraulic shovel, when the operator attempts to move the hydraulic shove straight forward by inputting substantially the same operation amounts into the unit 120 and the unit 130, even in case a load borne by the right side caterpillar becomes larger than a load borne by the left side caterpillar due to the right side caterpillar riding on a stone or the left side caterpillar entering a puddle, the movement of the right side caterpillar and the movement of the left side caterpillar can be made slower at substantially the same ratio.
- an electro-hydraulic actuation system 300 as an electro-hydraulic actuation system according to the second embodiment has a substantially similar configuration to that of the electro-hydraulic actuation system (refer to Fig. 1) according to the first embodiment, hereinafter, like reference numerals are imparted to constituent parts of the electro-hydraulic actuation system 300 which are substantially like to those of the electro-hydraulic actuation system 100 and the detailed description thereof will be omitted.
- the electro-hydraulic actuation system 300 includes an electro-hydraulic actuator 320 (refer to Figs. 10 to 14) and a unit 330, the detailed description of which will be omitted, having a similar configuration to that of the unit 320.
- the unit 320 has a variable displacement hydraulic motor 322 as a hydraulic actuator having formed therein a port 322a and a port 322b which are made to communicate with a variable displacement hydraulic pump 111 or a tank 112 and adapted to impart a driving force to reduction gears 121 by virtue of the pressure of a working fluid supplied to the port 322a and the port 322b.
- variable displacement hydraulic motor 322 has, as shown in Figs. 10 to 14, a box body 351, a box body 152 fixed to the box body 351, a swash plate 153, a motor shaft 154, a bearing 355 for rotatably supporting the motor shaft 154 on the box body 351, a bearing 156, a cylinder bock 157 having formed therein a plurality of cylinder chambers 157a, a plurality of pistons 158, shoe members 159, a spring 160 and a seal 162.
- the unit 320 has, as shown in Figs. 8 and 9, an electro-hydraulic servo valve 327 as a fluid volume changing valve having formed therein a port 327a which communicates with the variable displacement hydraulic pump 111, a part 327b which communicates with the tank 112, a port 327c which communicates with the port 322a of the variable displacement hydraulic motor 322, a part 327d which communicates with the port 322b of the variable displacement hydraulic motor 322, a port 327e and a port 327f, adapted to take any of a first position 327A, a second position 327B and a third position 328C based on the rotating amount of a second toothed shaft 125 and the driving amount of an electric motor 123 and adapted to change the volume of a working fluid discharged by the variable displacement hydraulic pump 111 for supply to the variable displacement hydraulic motor 32
- the first position 327A is a position where the port 327a is made to communicate with the port 327c and the port 327e and a communication of the port 327b with the port 327d and the port 327f is established
- the second position 327B is a position where the communication with the port 327a, the port 327b, the port 327c, the port 327d, the port 327e and the port 327f is cut off
- the third position 327C is a position where the port 327a is made to communicate with the port 327d and the port 327f and a communication of the port 327d with the port 327c and the port 327e is established.
- the electro-hydraulic servo valve 327 has a box body 151, a moving body 171 for changing the communication of the port 327a, the port 327b, the port 327c, the port 327d, the port 327e and the port 327f, a bearing 172 for transmitting an axial movement of the second toothed shaft 125 to the moving body 171 and a cap 173, a cap 174 and a seal 175 which prevent the leakage of a working fluid from the inside to the outside of the box body 151.
- the unit 320 has a bearing 361 and a bearing 362 which rotatably support a first toothed shaft 124 relative to the box body 151.
- the unit 320 has a load pressure selector valve 328 having formed therein a port 328a which communicates with the port 327c of the electro-hydraulic servo valve 327, a port 328b which communicates with the port 327d of the electro-hydraulic servo valve 327, a part 328c which communicates with the port 327e of the electro-hydraulic servo valve 327, a port 328d which communicates with the port 327f of the electro-hydraulic servo valve 327, a port 328e which communicates with the tank 112 and a port 328f which communicates with a port 141a of a selector valve 141, adapted to take any of the first position 328A, the second position 328B and the third position 328C based on the pressure of a working fluid supplied to the port 328c and the port 328d and adapted to make either of the port 328a and the port 328b to
- the first position 328A is a position where the port 328a is made to communicate with the port 328f and the communication between the port 328b and the port 328e is cut off
- the second position 328B is a position where the communication of the port 328a and the port 328b is cut off and the port 328e is made to communicate with the port 328f
- the third position 328C is a position where the communication of the port 328a and the port 328e are cut off and the port 328b is made to communicate with the port 328f.
- the load pressure selector valve 328 has, as shown in Figs. 10 to 14, the box body 151, a moving body 371 for changing the communication of the port 328a, the port 328b, the port 328c, the port 328d, the port 328e and the port 328f, a spring 329a for biasing the moving body 371 so that the moving body 371 is located at a first position 328A (refer to Fig. 9), a spring 329b for biasing the moving body 371 so that the moving body is located at a third position 328C (refer to Fig. 9) and a cap 372 and a cap 373 which prevent the leakage of the working fluid from the inside to the outside of the box body 151.
- the electro-hydraulic servo valve 327 of the unit 320, the load pressure selector valve 328, an electro-hydraulic servo valve 337 of the unit 330, a load pressure selector valve 338, a selector valve 141, a spring 142 and a discharge volume changing hydraulic cylinder 144 constitutes a discharge volume changing means for changing the working fluid discharge volume of the variable displacement hydraulic pump 111 based on a maximum pressure of pressures of the working fluid supplied to the variable displacement hydraulic motor 322 of the unit 320 and a variable displacement hydraulic motor 332 of the unit 330 and the working fluid discharge pressure of the variable displacement hydraulic pump 111.
- the load pressure selector valve 328 takes the first position 328A where a communication of the port 328a and the port 328f is established when the pressure of the working fluid supplied to the port 328c is greater than the pressure of the working fluid supplied to the port 328d, and takes a second position 328B when the pressure of the working fluid supplied to the port 328c is the same as the pressure of the working fluid supplied to the port 328d, and takes the third position 328C where a communication of the port 328b and the port 328f is established when the pressure of the working fluid supplied to the port 328c is smaller than the pressure of the working fluid supplied to the port 328d.
- the electro-hydraulic servo valve 327 allows the port 327c which communicates with the port 328a of the load pressure selector valve 328 to communicate with the port 327e which communicates with the port 328c of the load pressure selector valve 328 when the electro-hydraulic servo valve 327 makes the port 327a which communicates with the variable displacement hydraulic pump 111 or the port 327b which communicates with the tank 112 communicate with the port 327c, and allows the port 327d which communicates with the port 328d of the load pressure selector valve 328 to communicate with the port 327f which communicates with the port 328d of the load pressure selector valve 328 when the electro-hydraulic servo valve 327 makes the port 327a or the port 327b communicate with the port 327d.
- the pressure of the working fluid supplied to the port 328f of the load pressure selector valve 328 or the pressure of the working fluid supplied to a port 141a of the selector valve 141 becomes the load pressure of the variable displacement hydraulic motor 322 of the unit 320.
- the pressure of a working fluid supplied to a port 338f of the load pressure selector valve 338 or the pressure of a working fluid supplied to a port 141b of the selector valve 141 becomes the load pressure of the variable displacement hydraulic motor 332 of the unit 330.
- the electro-hydraulic actuation system 300 can change the working fluid discharge volume of the variable displacement hydraulic pump 111 so that a differential pressure between a larger load pressure of the load pressures of the variable displacement hydraulic motor 322 of the unit 320 and the variable displacement hydraulic motor 332 of the unit 330 and the working fluid discharge pressure of the variable displacement hydraulic pump 111 becomes a predetermined set pressure by the spring 143.
- an electro-hydraulic actuation system 500 as an electro-hydraulic actuation system according to the embodiment has a configuration which is substantially similar to that of the electro-hydraulic actuation system 100 (refer to Fig. 1) according to the first embodiment or the electro-hydraulic actuation system 300 (refer to Fig. 8) according to the second embodiment, hereinafter, like reference numerals are imparted to constituent parts of the electro-hydraulic actuation system 500 which are substantially like to those of the electro-hydraulic actuation system 100 or the electro-hydraulic actuation system 300, and the detailed description thereof will be omitted.
- the electro-hydraulic actuation system 500 includes, as electro-hydraulic actuators, a unit 520 (refer to Figs. 17 to 20) and a unit 530, the detailed description of which will be omitted, having a similar configuration to that of the unit 520, instead of the unit 120 (refer to Fig. 1) and the unit 130 (refer to Fig. 1) of the electro-hydraulic actuation system 100 (refer to Fig. 1).
- the unit 520 has, instead of the electro-hydraulic servo valve 127 of the unit 120 (refer to Fig. 1), an electro-hydraulic servo valve 527 as a fluid volume changing valve having formed therein a port 527a which communicates with a variable displacement hydraulic pump 111, a port 527b which communicates with a tank 112, a port 527c which communicates with a port 122a of a hydraulic motor 122 and a port 527d which communicates with a port 122b of the hydraulic motor 122, adapted to take any of a first position 527A, a second position 527B and a third position 527C based on the rotating amount of a second toothed shaft 125 and the driving amount of an electric motor 123 and adapted to change the volume of a working fluid discharged by the variable displacement hydraulic pump 111 for supply to the hydraulic motor 122.
- an electro-hydraulic servo valve 527 as a fluid volume changing valve having formed therein a port 527a
- the first position 527A is a position where the port 527a is made to communicate with the port 527c, and the port 527b is made to communicate with the port 527d
- the second position 527B is a position where the communication of the port 527a, the port 527b, the port 527c and the port 527d is cut off
- the third position 527C is a position where the port 527a is made to communicate with the port 527d, and the port 527b is made to communicate with the port 527c.
- the electro-hydraulic servo valve 527 has a box body 151, a moving body 171 for changing the communication of the port 527a, the port 527b, the port 527c and the port 527d, a bearing 172 for transmitting an axial movement of the second toothed shaft 125 to the moving body 171 and a cap 173, a cap 174 and a seal 175 which prevent the leakage of a working fluid from the inside to the outside of the box body 151.
- the electro-hydraulic actuation system 500 includes a pressure setting valve 545 for setting a pressure for a working fluid supplied to a port 142d of a two-position valve 142 by being switched between a position where a working fluid discharged by the variable displacement hydraulic pump 111 is led to the port 142d of the two-position valve 142 via a throttle 140a and a position where the working fluid discharged by the variable displacement hydraulic pump 11 is led to the tank 112 based on the pressure of the working fluid supplied to the port 142d of the two-position valve 142 and a signal inputted via a signal wire 545a.
- a computer, not shown, of the electro-hydraulic actuation system 500 is configured to receive pressures detected by a pressure gauge 145, a pressure gauge 146, a pressure gauge 147, a pressure gauge 148 and a pressure gauge 149 for input thereinto, change the rotational speed of the electric motor 123 of the unit 520 and an electric motor 133 of the unit 530 at substantially the same ratio relative to the electric motor 123 and the electric motor 133 based on the pressures so inputted, produce a signal based on the inputted pressures and input the signal so produced into the two-position electromagnetic valve 514.
- the computer is configured to select a driving side pressure while following the motor rotating direction of the hydraulic motors 122 and 132 based on values of the pressures inputted from the pressure gauge 145, the pressure gauge 146, the pressure gauge 147 and the pressure gauge 148, select a greatest pressure of the pressures of the hydraulic motor 122 and the hydraulic motor 132 and input the pressure so selected into the pressure setting valve 545 as a signal via the signal wire 545a.
- the pressure gauge 145, the pressure gauge 146, the pressure gauge 147, the pressure gauge 148, the pressure gauge 149, the computer, not shown, the pressure setting valve 545, the two-position valve 142, a spring 143 and a discharge volume changing hydraulic cylinder 144 constitutes a discharge volume changing means for changing the working fluid discharge volume of the variable displacement hydraulic pump 111 based on the greatest pressure of the pressures of the working fluid supplied to the hydraulic motor 122 of the unit 520 and the hydraulic motor 132 of the unit 530 and the working fluid discharge pressure of the variable displacement hydraulic pump 111.
- the pressure setting valve 545 produces a force in accordance with the signal so inputted and changes positions based on the force so produced and the pressure of the working fluid supplied to the port 142d of the two-position valve 142.
- the pressure setting valve 545 when the force produced in accordance with the signal inputted is greater than a force produced by virtue of the pressure of the working fluid supplied to the port 142d of the two-position valve 142, the pressure setting valve 545 is switched to a position where the working fluid discharged by the variable displacement hydraulic pump 111 is led to the port 142d of the two-position valve 142 via the throttle 140a and when the force produced in accordance with the signal inputted is equal to or smaller than the force produced by virtue of the pressure of the working fluid supplied to the port 142d of the two-position valve 142, the pressure setting valve 545 is switched to a position where the working fluid discharged by the variable displacement hydraulic pump 111 is led to the tank 112.
- the pressure setting valve 545 is configured to produce a force which allows the computer, not shown, to implement a feedback using the pressure from the pressure gauge 149 so that the pressure of the working fluid supplied to the port 142d of the two-position valve 142 becomes a sum of the pressure selected from the hydraulic motor 122 of the unit 520 and the hydraulic motor 132 of the unit 530 and a pressure allowance that is determined in advance.
- the pressure of the working fluid supplied to the port 142d of the two-position valve 142 becomes substantially the same as the sum of the pressure selected from the hydraulic motor 122 of the unit 520 and the hydraulic motor 132 of the unit 530 and the pressure allowance that is determined in advance, and as has been described in the first embodiment, the electro-hydraulic actuation system 500 can change the working fluid discharge volume of the variable displacement hydraulic pump 111 so as to become the sum of the greater pressure of the pressures of the hydraulic motor 122 of the unit 520 and the hydraulic motor 132 of the unit 530 and the pressure allowance that is determined in advance.
- the computer when determining that there has occurred a shortage in volume of the working fluid supplied to either of the hydraulic motor 122 of the unit 520 and the hydraulic motor 132 of the unit 530 based on the pressures inputted from the pressure gauge 145, the pressure gauge 146, the pressure gauge 147, the pressure gauge 148 and the pressure gauge 149, the computer, not shown, generates a signal which locates the two-position electromagnetic valve 514 at the first position 514A and inputs the signal so generated into the two-position electromagnetic valve 545.
- the two-position electromagnetic valve 514 When the two-position electromagnetic valve 514 is located at the first position 514A in response to the signal inputted from the computer, not shown, since the set pressure of the relief valve 113 becomes largest within a designed range, the pressure of the working fluid discharged by the variable displacement hydraulic pump 111 for supply to the unit 520 and the unit 530 can be increased to a set pressure of the relief valve 113 which is greatest within the designed range.
- the computer when determining that there has occurred a shortage in volume of the working fluid supplied to either of the hydraulic motor 122 of the unit 520 and the hydraulic motor 132 of the unit 530 based on the pressures inputted from the pressure gauge 145, the pressure gauge 146, the pressure gauge 147, the pressure gauge 148 and the pressure gauge 149, the computer, not shown, reduces the rotational speed of the electric motor 123 and the electric motor 133 at the same or a predetermined ratio, thereby making it possible to prevent a state in which the volume of working fluid is short.
- the computer when determining that there is occurring no shortage in volume of the working fluid supplied to the hydraulic motor 122 of the unit 520 and the hydraulic motor 132 of the unit 530 based on the pressures inputted from the pressure gauge 145, the pressure gauge 146, the pressure gauge 147, the pressure gauge 148 and the pressure gauge 149, the computer, not shown, produces a signal which locates the two-position electromagnetic valve 514 at the second position 514B and inputs the signal so produced to the two-position electromagnetic valve 514.
- the two-position electromagnetic valve 514 When the two-position electromagnetic valve 514 is located at the second position 514B in response to the signal inputted from the computer, not shown, since the set pressure of the relief valve 113 becomes smallest within the designed range, the pressure of the working fluid discharged by the variable displacement hydraulic pump 111 for supply to the unit 520 and the unit 530 can only be increased to a set pressure of the relief valve 113 which is smallest within the designed range.
- the electro-hydraulic actuation system 500 can suppress the pressure of working fluid discharged by the variable displacement hydraulic pump 111 for supply to the unit 520 and the unit 530 to the set pressure of the relief valve 113 which is the smallest within the designed range or smaller and can reduce energy consumed by the variable displacement hydraulic pump 111 when compared with a case where the two-position electromagnetic valve 514 is provided.
- the computer In addition, in a state where the rotational speed inputted is 0, the computer, not shown, outputs to the pressure setting valve 545 a signal which makes the discharge pressure of the variable displacement hydraulic pump 111 become a predetermined low pressure based on the pressure of the pressure gauge 149, thereby making it possible to reduce energy consumed. Additionally, in the state where the rotational speed inputted is 0, the computer, not shown, outputs to the pressure setting valve 545 a signal which makes the discharge pressure of the variable displacement hydraulic pump 111 become a predetermined low pressure based on the pressure of the pressure gauge 149, thereby making it possible to reduce energy consumed.
- an electro-hydraulic actuation system 600 as an electro-hydraulic actuation system according to the embodiment has a substantially similar configuration to that of the electro-hydraulic actuation system 500 (refer to Fig. 15) according to the third embodiment, hereinafter, like reference numerals are imparted to constituent parts of the electro-hydraulic actuation system 600 which are substantially like to those of the electro-hydraulic actuation system 500.
- the electro-hydraulic actuation system 600 includes, instead of the two-position electromagnetic valve 514 (refer to Fig. 15) of the electro-hydraulic actuation system 500 (refer to Fig. 15), a two-position electromagnetic valve 614 having formed therein a port 614a which communicates with a variable displacement hydraulic pump 111, a unit 520 and a unit 530, a port 614b which communicates with a tank 112 and a port 614c which communicates with a relief valve 113 and adapted to take based on a signal inputted either of a first position where the communication of the port 614a and the port 614b is established and a second position where the communication of the port 614a and the port 614c is established.
- a computer, not shown, of the electro-hydraulic actuation system 600 is configured to receive pressures detected by a pressure gauge 145, a pressure gauge 146, a pressure gauge 147, a pressure gauge 148 and a pressure gauge 149 for input thereinto, produce a signal based on the pressures inputted and input the signal produced into the two-position electromagnetic valve 614.
- the computer when determining that there has occurred a shortage in volume of the working fluid supplied to either of the hydraulic motor 122 of the unit 520 and the hydraulic motor 132 of the unit 530 based on the pressures inputted from the pressure gauge 145, the pressure gauge 146, the pressure gauge 147, the pressure gauge 148 and the pressure gauge 149, the computer, not shown, generates a signal which locates the two-position electromagnetic valve 614 at the second position 614B and inputs the signal so generated into the two-position electromagnetic valve 614.
- the two-position electromagnetic valve 614 takes the second position 614B in response to the signal inputted from the computer, not shown, since the port 614a which communicates with the variable displacement hydraulic pump 111, the unit 520 and the unit 530 communicates with the port 614c which communicates with the relief valve 113, the pressure of a working fluid discharged by the variable displacement hydraulic pump 111 for supply to the unit 520 and the unit 530 can be increased to a set pressure for the relief valve 113.
- the computer when determining that there is occurring no shortage in volume of the working fluid supplied to the hydraulic motor 122 of the unit 520 and the hydraulic motor 132 of the unit 530 based on the pressures inputted from the pressure gauge 145, the pressure gauge 146, the pressure gauge 147, the pressure gauge 148 and the pressure gauge 149, the computer, not shown, generates a signal which locates the two-position electromagnetic valve 614 at the first position 614A and inputs the signal so generated into the two-position electromagnetic valve 614.
- the two-position electromagnetic valve 614 takes the first position 614A in response to the signal inputted from the computer, not shown, since the port 614a which communicates with the variable displacement hydraulic pump 111, the unit 520 and the unit 530 communicates with the port 614b which communicates with the tank 112, the pressure of the working fluid discharged by the variable displacement hydraulic pump 111 for supply to the unit 520 and the unit 530 is reduced when compared to the case where the two-position electromagnetic valve 614 takes the second position 614B.
- the electro-hydraulic actuator system 600 can suppress the pressure of the working fluid discharged by the variable displacement hydraulic pump 111 for supply to the unit 520 and the unit 530 when there is occurring no shortage in volume of the working fluid supplied to the hydraulic motor 122 of the unit 520 and the hydraulic motor 132 of the unit 530 to a smaller value when compared with when there is occurring a shortage in volume of the working fluid supplied to the hydraulic motor 122 of the unit 520 and the hydraulic motor 132 of the unit 530 and can reduce energy consumed by the variable displacement hydraulic pump 111 when compared with a case where the two-position electromagnetic valve 614 is not provided.
- the liquid pump according to the invention is a liquid pump for discharging a liquid from a liquid storage portion to at least one predetermined position and is configured to have at least one cylinder chamber formed for induction of the liquid thereinto from the liquid storage portion, a piston disposed in the cylinder chamber, a liquid discharge port formed in the cylinder chamber and a driving means for driving the piston so as to drive, in turn, a cylinder in axial directions within the cylinder chamber.
- the piston is inserted from one end portion of the cylinder chamber, and the liquid discharge port is disposed at the other end portion of the cylinder chamber.
- a pair of cylinder chambers is disposed at both ends of the piston, a piston is inserted from one end of each cylinder chamber, and a liquid discharge port is opened in the other end of each cylinder chamber.
- liquid can be supplied to two locations per one piston.
- the cross-sectional shape and/or length is optimized in accordance with the supply volume of liquid.
- the volume of fluid supplied can be adjusted even in case the operation frequency of the piston is identical.
- the supply volume of fluid per cylinder chamber can be altered.
- the piston is inserted into the cylinder chamber, and a single or a plurality of liquid discharge ports are formed in the cylinder chamber.
- liquid can be supplied to a plurality of locations or two or more locations per piston.
- liquid pump In the liquid pump according to the invention, a construction is adopted in which a single or a plurality of stepped portions are formed in the cylinder chamber, the piston is formed so as to have a substantially equal shape to that of the cylinder chamber, and a liquid discharge port is disposed at the single or each of the plurality of stepped portions formed in the cylinder chamber.
- the single or the plurality of stepped portions in the cylinder chamber are formed in such a manner as to be substantially symmetrical in the axial direction, the piston is formed into a substantially equal shape to the formation of the substantially symmetrical stepped portions, and a liquid discharge port is formed in the single or each of the plurality of stepped portions formed in the cylinder chamber.
- a member is disposed for forming the single or the plurality of stepped portions substantially symmetrically in the cylinder chamber.
- the relative axial length of the cylinder chamber and the piston and/or cross sectional areas thereof which are normal to their axes are optimized in accordance with the volume of liquid supplied.
- the volume of fluid supplied can be adjusted.
- the supply volume of fluid per cylinder chamber can be altered.
- a liquid bleeder hole is provided in the cylinder chamber.
- a plurality of constructions are disposed in series in which a single or a plurality of stepped portions are formed in a hollow portion of the cylinder chamber and a cross-sectional area of each stepped portion which is normal to the axis thereof is gradually increased as it extends along the axial direction thereof.
- the piston and the cylinder chamber are provided in a plural number for a single driving means.
- the configuration like this there is no need to provide a plurality of driving means for moving the pluralities of pistons and cylinder chambers, thereby making it possible to reduce the number of components.
- the driving means is made up of a solenoid which is made up of, in turn, a shaft portion which is wholly or partially made of a magnetic material and a solenoid coil which are adapted to move relative to each other, the shaft portion and the solenoid coil are separated by a bulkhead so that the shaft portion and the solenoid coil are not in contact with each other, and the shaft portion and the piston are made to interlock with each other by a predetermined connecting means.
- a bulkhead made of a non-magnetic material is used for the bulkhead.
- a magnetic field produced in the solenoid coil is allowed to pass only a plunger made of a magnetic material, thereby making it possible to increase an attractive force between the plunger and a base.
- the solenoid is used as the driving means, and furthermore, the liquid pump is used as a lubricating oil circulating pump, whereby portions needing lubrication and lubricating paths, and a lubricating oil discharge main part of the lubricating oil circulating pump are sealed.
- the portions where lubricating oil is circulated and the piston, which is a sliding part of the lubricating oil circulating pump, and the driving portion therefor can be sealed, whereby no seal is needed at portions where sliding or/and rotating motions occur, thereby making it possible to reduce the possibility of lubricating oil leakage.
- the lubricating oil circulating portion resides in a vacuum, it is possible to eliminate as much as possible a concern that outside air intrudes from seals at the sliding or/and rotating portions to thereby deteriorate the degree of vacuum.
- a lubricating storage tank for storing lubricating oil, which is in communication for induction of the lubricating oil thereinto, is formed, and a lubricating oil supply pump and supply paths are disposed in the apparatus having rotating portions for supplying the oil from the lubricating oil storage tank to predetermined portions such as the bearings and gears.
- the apparatus having rotating portions according to the invention is characterized in that the main part for discharging a lubricating oil of the lubricating oil supply pump is formed integrally in the lubricating oil storage tank.
- the lubricating oil storage tank is disposed at a position where the lubricating oil in the apparatus having rotating portions flows into by virtue of its own gravity.
- the liquid pumps set forth in Claims 1 to 15 are used as the pump.
Abstract
An object of the invention is to provide an
electro-hydraulic actuation system which can prevent the
generation of a shortage in volume of a fluid supplied to a
hydraulic actuator having a larger load pressure of hydraulic
actuators of a plurality of electro-hydraulic actuators. The
electro-hydraulic actuation system 100 changes a working fluid
discharge volume of a variable displacement hydraulic pump 111
by a selector valve 141, a two-position valve 142, a spring 143
and a discharge volume changing hydraulic cylinder 144 based
on the maximum pressure of load pressures of a hydraulic motor
122 and a hydraulic motor 132 and a working fluid discharge
pressure of the variable displacement hydraulic pump 111.
Description
- The present invention relates to an electro-hydraulic actuation system for use in a hydraulic shovel or asphalt finisher and more particularly to an electro-hydraulic actuation system to which a load sensing system (hereinafter, referred to as LS) is applied for changing the discharge volume of a pump based on the load pressure of an actuator so that a differential pressure between the load pressure of the actuator and the discharge pressure of the pump becomes substantially constant.
- Conventionally, as a hydraulic actuation system to which the LS is applied, there has been known, for example, a
hydraulic actuation system 900 shown in Fig. 22. - The
hydraulic actuation system 900 includes a variable displacementhydraulic pump 911 for discharging a working fluid, atank 912 from which the working fluid is discharged and arelief valve 913 for keeping the working fluid discharge pressure of the variable displacementhydraulic pump 911 at a predetermined set pressure or lower. - In addition, the
hydraulic actuation system 900 includes aunit 920 havingreduction gears 921 connected to a load, not shown, a variable displacementhydraulic motor 922 for imparting a driving force to thereduction gears 921, anoperation lever 923 adapted to be operated by an operator, a manualdirection control valve 924 for changing the communication of the variable displacementhydraulic pump 911 and thetank 912 with the variable displacementhydraulic motor 922 in accordance with the operation amount of theoperation lever 923 and an automatic two-position valve 925 for cutting off the communication of the variable displacementhydraulic pump 911 and thetank 912 with the variable displacementhydraulic motor 922 in accordance with the operation amount of theoperation lever 923 when the communication of the variable displacementhydraulic pump 911 and thetank 912 with the variable displacementhydraulic motor 922 in accordance with the operation amount of theoperation lever 923 is cut off by the manualdirection control valve 924. - In addition, the
hydraulic actuation system 900 includes aunit 930 having a similar configuration to that of theunit 920, while the detailed description of theunit 930 is omitted here. - Additionally, the
hydraulic actuation system 900 includes aselector valve 941 for selecting a working fluid having a greater pressure of a working fluid supplied from the variable displacementhydraulic pump 911 to the variable displacementhydraulic motor 922 of theunit 920 and a working fluid supplied to the variable displacementhydraulic pump 911 to a variable displacementhydraulic motor 932 of theunit 930, a two-positionelectromagnetic valve 942 for allowing the working fluid discharged by the variable displacementhydraulic pump 911 to pass when a pressure resulting from adding a predetermined set pressure to the pressure of the working fluid selected by theselector valve 941 is greater than the working fluid discharge pressure of the variable displacementhydraulic pump 911 discharges the working fluid, a discharge volume changinghydraulic cylinder 943 for changing the discharge volume of the variable displacementhydraulic pump 911 based on the pressure of the working fluid which is allowed to pass by the two-positionelectromagnetic valve 942 and the working fluid discharge pressure of the variable displacementhydraulic pump 911. - By the configuration that has been described above, the discharge volume changing
hydraulic cylinder 943 used to change the working fluid discharge volume of the variable displacementhydraulic pump 911 so that a difference between a larger pressure of the pressure of the working fluid supplied from the variable displacementhydraulic pump 911 to the variable displacementhydraulic motor 922 of theunit 920, that is, the load pressure of theunit 920 and the pressure of the working fluid supplied from the variable displacementhydraulic pump 911 to the variable displacementhydraulic motor 932 of theunit 930, that is, the load pressure of theunit 930 and the working fluid discharge pressure of the variable displacementhydraulic pump 911 becomes the set pressure of the two-positionelectromagnetic valve 942. - In the conventional
hydraulic actuation system 900, however, there was a problem that the amount of the working fluid is short which is supplied to the variable displacement hydraulic motor having a larger load pressure of the variable displacementhydraulic motor 922 of theunit 920 and the variable displacementhydraulic motor 932 of theunit 930. - When the load pressure of the variable displacement
hydraulic motor 922 of theunit 920 or the variable displacementhydraulic motor 932 of theunit 930 is increased, the working fluid discharge pressure of the variable displacementhydraulic pump 911 is increased due to the actions of theselector valve 941, the two-positionelectromagnetic valve 942 and the discharge volume changinghydraulic cylinder 943. However, in a case where the relationship between the working fluid discharge volume and discharge pressure of the variable displacementhydraulic pump 911 is such as shown in Fig. 23, namely, in a case where the variable displacementhydraulic pump 911 is a pump whose horse power is constant, the working fluid discharge volume of the variable displacementhydraulic pump 911 decreases as the working fluid discharge pressure thereof increases. - Here, when the working fluid discharge volume of the variable displacement
hydraulic pump 911 becomes smaller than a total amount of working fluid needed to be supplied to the variable displacementhydraulic motor 922 of theunit 920 and the variable displacementhydraulic motor 932 of theunit 930, the working fluid discharged by the variable displacementhydraulic pump 911 flows to the variable displacement hydraulic motor having a smaller load pressure in preference to the other. - Then, there occurs a shortage in volume of the working fluid supplied to the variable displacement hydraulic motor having a larger load pressure of the variable displacement
hydraulic motor 922 of theunit 920 and the variable displacementhydraulic motor 932 of theunit 930, and the output thereof is reduced when compared with a case where there occurs no shortage in volume of the working fluid supplied thereto. - Consequently, for example, in a case where the variable displacement
hydraulic motor 922 of theunit 920 is used for driving a right side caterpillar of a hydraulic shovel and the variable displacementhydraulic motor 932 of theunit 930 is used for a left side caterpillar of the hydraulic shovel, when the operator attempts to move the hydraulic shovel straight forward by inputting substantially equal operation amounts to theoperation lever 923 of theunit 920 and anoperation lever 933 of theunit 930, in the event that a load borne by the right side caterpillar becomes larger than a load borne by the left side caterpillar as a result of, for example, the right side caterpillar riding on a stone or the left side caterpillar entering a puddle, the movement of the right side caterpillar becomes slower than the movement of the left side caterpillar, and the hydraulic shovel advances while turning to the right. - Then, an object of the invention is to provide an electro-hydraulic actuation system which can prevent the generation of a shortage in volume of a fluid supplied to a hydraulic actuator having a larger load pressure of hydraulic actuators of a plurality of electro-hydraulic actuators.
- With a view to solving the problem, according to the invention, there is provided an electro-hydraulic actuation system including a pump, a plurality of electro-hydraulic actuators each having an electric motor, a hydraulic actuator and a fluid volume changing valve for changing the volume of a fluid discharged by the pump based on driving amounts of the electric motor and the hydraulic actuator for supply to the hydraulic actuator, a discharge volume changing means for changing the volume of the fluid discharged by the pump based on a maximum pressure of pressures of the fluid supplied to the hydraulic actuators of the plurality of electro-hydraulic actuators and the discharge pressure of the fluid discharged by the pump and a rotational speed changing means for changing the rotational speed of the electric motors of the plurality of electro-hydraulic actuators at substantially the same ratio relative to the electric motors of the plurality of electro-hydraulic actuators based on a maximum pressure of pressures of the fluid supplied to the hydraulic actuators of the plurality of electro-hydraulic actuators and the discharge pressure of the fluid discharged by the pump.
- By adopting this configuration, since the electro-hydraulic actuation system of the invention can reduce the volume of the fluid supplied to the hydraulic actuators of the plurality of electro-hydraulic actuators at substantially the same ratio when there occurs a shortage in volume of the fluid supplied to the hydraulic actuators of the plurality of electro-hydraulic actuators, it is possible to prevent the occurrence of a shortage in volume of the fluid supplied to the actuator having a larger load pressure of the hydraulic actuators of the plurality of electro-hydraulic actuators.
-
- Fig. 1 is a hydraulic circuit diagram of an electro-hydraulic actuation system according to a first embodiment of the invention.
- Fig. 2 is a hydraulic circuit diagram of the electro-hydraulic actuation system shown in Fig. 1 in the vicinity of an electro-hydraulic servo valve thereof.
- Fig. 3 is a hydraulic circuit diagram of the electro-hydraulic actuation system shown in Fig. 1 in the vicinity of a discharge volume changing hydraulic cylinder thereof.
- Fig. 4 is a sectional view of a unit of the electro-hydraulic actuation system shown in Fig. 1.
- Fig. 5 is a sectional view taken along the line indicated by arrows A-A in Fig. 4 and viewed in a direction indicated by the arrows.
- Fig. 6 is a sectional view taken along the line indicated by arrows B-B in Fig. 4 and viewed in a direction indicated by the arrows.
- Fig. 7 is a sectional view taken along the line indicated by arrows C-C in Fig. 4 and viewed in a direction indicated by the arrows.
- Fig. 8 is a hydraulic circuit diagram of an electro-hydraulic actuation system according to a second embodiment of the invention.
- Fig. 9 is a hydraulic circuit diagram of the electro-hydraulic actuation system shown in Fig. 8 in the vicinity of an electro-hydraulic servo valve thereof.
- Fig. 10 is a sectional view of a unit of the electro-hydraulic actuation system shown in Fig. 8.
- Fig. 11 is a sectional view taken along the line indicated by arrows E-E in Fig. 10 and viewed in a direction indicated by the arrows.
- Fig. 12 is a sectional view taken along the line indicated by arrows F-F in Fig. 10 and viewed in a direction indicated by the arrows.
- Fig. 13 is a sectional view taken along the line indicated by arrows G-G in Fig. 10 and viewed in a direction indicated by the arrows.
- Fig. 14 is a sectional view taken along the line indicated by arrows H-H in Fig. 10 and viewed in a direction indicated by the arrows.
- Fig. 15 is a hydraulic circuit diagram of an electro-hydraulic actuation system according to a third embodiment of the invention.
- Fig. 16 is a hydraulic circuit diagram of the electro-hydraulic actuation system shown in Fig. 15 in the vicinity of an electro-hydraulic servo valve thereof.
- Fig. 17 is a sectional view of a unit of the electro-hydraulic actuation system shown in Fig. 15.
- Fig. 18 is a sectional view taken along the line indicated by arrows J-J in Fig. 17 and viewed in a direction indicated by the arrows.
- Fig. 19 is a sectional view taken along the line indicated by arrows K-K in Fig. 17 and viewed in a direction indicated by the arrows.
- Fig. 20 is a sectional view taken along the line indicated by arrows L-L in Fig. 17 and viewed in a direction indicated by the arrows.
- Fig. 21 is a hydraulic circuit diagram of an electro-hydraulic actuation system according to a fourth embodiment of the invention.
- Fig. 22 is a hydraulic circuit diagram of a conventional electro-hydraulic actuation system.
- Fig. 23 is a diagram showing the discharge volume and discharge pressure of a variable displacement hydraulic pump of the electro-hydraulic actuation system shown in Fig. 22.
-
- Embodiments of the invention will be described below using the drawings.
- Firstly, the configuration of an electro-hydraulic actuation system according to a first embodiment will be described.
- In Figs. 1 to 3, an electro-
hydraulic actuation system 100 as an electro-hydraulic actuation system according to the first embodiment includes a variable displacementhydraulic pump 111 as a pump of a constant horse power for discharging a working fluid (fluid), atank 112 from which the working fluid is discharged and arelief valve 113 for keeping the working fluid discharge pressure of the variable displacementhydraulic pump 111 at a predetermined set pressure or lower. - In addition, the electro-
hydraulic actuation system 100 includes a unit (refer to Figs. 4 to 7) as an electro-hydraulic actuator havingreduction gears 121 connected to a load not shown, ahydraulic motor 122 as a hydraulic actuator having formed therein aport 122a and aport 122b which are made to communicate with the variable displacementhydraulic pump 111 or thetank 112 and adapted to impart a driving force to thereduction gears 121 by virtue of the pressure of a working fluid supplied to theport 122a and theport 122b, anelectric motor 123 driven in accordance with an electric signal entered, a firsttoothed shaft 124 adapted to rotate together with a driving shaft of thehydraulic motor 122 and a secondtoothed shaft 125 which is brought into a screw connection with a rotating shaft of theelectric motor 123 and is brought into a mesh engagement with the firsttoothed shaft 124. - Here, the
hydraulic motor 122 has, as shown in Figs. 4 to 7, abox body 151 to which theelectric motor 123 is fixed, abox body 152 fixed to thebox body 151, aswash plate 153 fixed in the interior of thebox body 152, amotor shaft 154 connected to thereduction gears 121 at one end and brought into engagement with the firsttoothed shaft 124 at the other end thereof in such a manner as to rotate in synchronism with the firsttoothed shaft 124, abearing 155 and abearing 156 which rotatably support themotor shaft 154 on thebox body 151 and thebox body 152, respectively, a cylinder block into which themotor shaft 154 is inserted at the center thereof, in which a plurality ofcylinder chambers 157a are formed and which is in engagement with themotor shaft 154 in such a manner as to rotate in synchronism with themotor shaft 154, a plurality ofpistons 158 accommodated in thecylinder chambers 157a in thecylinder block 157,shoe members 159 mounted on distal ends of thepistons 158, aspring 160 for biasing thecylinder block 157 towards thebox body 151 side and aseal 161 and aseal 162 for preventing the leakage of a working fluid. - In addition, the
unit 120 has, as shown in Figs. 1 to 3, an electro-hydraulic servo valve 127 as a fluid volume changing valve having formed therein aport 127a communicating with the variable displacementhydraulic pump 111, aport 127b communicating with thetank 112, aport 127c communicating with theport 122a of thehydraulic motor 122, aport 127d communicating with theport 122b of thehydraulic motor 122 and aport 127e, adapted to take any of afirst position 127A, asecond position 127B and athird position 127C based on the rotating amount of thesecond toothed shaft 125 and the driving amount of theelectric motor 123 and adapted to change the volume of a working fluid discharged by the variable displacementhydraulic pump 111 for supply to thehydraulic motor 122. - Note that the
first position 127A is a position where theport 127a is made to communicate with theport 127c and theport 127e, and theport 127b is made to communicate with theport 127d, thesecond position 127B is a position where the communication between theport 127a,port 127c andport 127d is cut off, while theport 127b is made to communicate with theport 127e, and thethird position 127C is a position where the communication between theport 127a,port 127d andport 127e is established, and theport 127b is made to communicate with theport 127c. - Here, the electro-
hydraulic servo motor 127 has, as shown in Figs. 4 to 7, a movingbody 171 for changing the communication of thebox body 151 with theport 127a,port 127b,port 127c,port 127d andport 127e, abearing 172 for transmitting an axial movement of the secondtoothed shaft 125 to the movingbody 171 and acap 173, acap 174, theseal 161 and aseal 175 which are adapted to prevent the leakage of working fluid from the inside to the outside of thebox body 151. - In addition, the
unit 120 has, as shown in Figs. 1 to 3, acheck valve 128a (refer to Fig. 5) disposed between the variable displacementhydraulic pump 111 and theport 127a of the electro-hydraulic servo valve 127 for preventing the passage of a working fluid from theport 127a of the electro-hydraulic servo valve 127 to the variable discharge volumehydraulic valve 111, acheck valve 128b (refer to Figs. 6 and 7) disposed between theport 122a of thehydraulic motor 122 and theport 127c of the electro-hydraulic servo valve 127 and thetank 112 for preventing the passage of a working fluid from theport 122a of thehydraulic motor 122 and theport 127c of the electro-hydraulic servo valve 127 to thetank 112 and acheck valve 128c (refer to Figs. 6 and 7) disposed between theport 122b of thehydraulic motor 122 and theport 127c of the electro-hydraulic servo valve 127 and thetank 112 for preventing the passage of a working fluid from theport 122b of thehydraulic motor 122 and theport 127c of the electro-hydraulic servo valve 127 to thetank 112. - In addition, while a detailed description is omitted, the electro-
hydraulic actuation system 100 has aunit 130 having a similar configuration to that of theunit 120. - Additionally, the electro-
hydraulic actuation system 100 includes aselector valve 141 having formed therein aport 141a which communicates with theport 127e of the electro-hydraulic servo valve 127 of theunit 120, aport 141b which communicates with aport 137e of an electro-hydraulic servo valve 137 of theunit 130 and aport 141c and adapted to select the port having a maximum pressure of theport 141a and theport 141b for establishing a communication between the port so selected and theport 141c. - In addition, the electro-
hydraulic actuation system 100 includes a two-position valve 142 having formed therein aport 142a which communicates with thetank 112, aport 142b and aport 142c which communicate with the variable displacementhydraulic pump 111, aport 142d which communicates with theport 141c of theselector valve 141 via athrottle valve 140a and aport 142e and adapted to take either of afirst position 142A where theport 142a and theport 142e are made to communicate with each other in accordance with the pressure of a working fluid supplied to theport 142c and theport 142e and asecond position 142B where theport 142b and theport 142e are made to communicate with each other. - Additionally, the electro-
hydraulic actuation system 100 includes aspring 143 for biasing the two-position valve 142 so that the two-position valve 142 takes thefirst position 142A when the pressure of a working fluid supplied to theport 142c of the two-position valve 142 is equal to or lower than a pressure resulting from adding a predetermined set pressure to the pressure of a working fluid supplied to theport 142d of the two-position valve 142. - In addition, the electro-
hydraulic actuation system 100 includes a discharge volume changinghydraulic cylinder 144 having formed therein acylinder chamber 144a which communicates with theport 142e of the two-position valve 142 via athrottle valve 140b and acylinder chamber 144b which communicates with the variable displacementhydraulic pump 111, connected with the variable displacementhydraulic pump 111 in such a manner to increase the discharge volume of the variable displacementhydraulic pump 111 when retracted than extended and adapted to be extended when the pressure of a working fluid within thecylinder chamber 144a is equal to or greater than the pressure of a working fluid within thecylinder chamber 144b and to be retracted when the pressure of the working fluid within thecylinder chamber 144a is smaller than the pressure of the working fluid within thecylinder chamber 144b. - Here, the electro-
hydraulic servo valve 127 of theunit 120, the electro-hydraulic servo valve 137 of theunit 130, theselector valve 141, the two-position valve 142, thespring 143 and the discharge volume changinghydraulic cylinder 144 constitutes a discharge volume changing means for changing the discharge pressure of a working fluid discharged by the variable displacementhydraulic pump 111 based on a maximum pressure of pressures of the working fluid supplied to thehydraulic motor 122 of theunit 120 and thehydraulic motor 132 of theunit 130 and the discharge pressure of the working fluid discharged by the variable displacementhydraulic pump 111. - In addition, the electro-
hydraulic actuation system 100 includes apressure gauge 145 for detecting the pressure of a working fluid supplied to theport 122a of thehydraulic motor 122 of theunit 120, apressure gauge 146 for detecting the pressure of a working fluid supplied to theport 122b of thehydraulic motor 122, apressure gauge 147 for detecting the pressure of a working fluid supplied to theport 132a of thehydraulic motor 132 of theunit 130, apressure gauge 148 for detecting the pressure of a working fluid supplied to theport 132b of thehydraulic motor 132, apressure gauge 149 for detecting the working fluid discharge pressure of the variable displacementhydraulic pump 111 and a computer, not shown, to which pressures detected by thepressure gauge 145, thepressure gauge 146, thepressure gauge 147, thepressure gauge 148 and thepressure gauge 149 are inputted for changing the rotation speed of theelectric motor 123 of theunit 120 and theelectric motor 133 of theunit 130 based on the pressures so inputted at substantially the same ratio relative to theelectric motor 123 and theelectric motor 133. - Here, the
pressure gauge 145, thepressure gauge 146, thepressure gauge 147, thepressure gauge 148, thepressure gauge 149 and the computer, not shown, constitute a rotational speed changing means for changing the rotational speed of theelectric motor 123 of theunit 120 and theelectric motor 133 of theunit 130 at substantially the same ratio relative to theelectric motor 123 of theunit 120 and theelectric motor 133 of theunit 130 based on a maximum pressure of pressures of the working fluid supplied to thehydraulic motor 122 of theunit 120 and thehydraulic motor 132 of theunit 130 and the working fluid discharge pressure of the variable displacementhydraulic pump 111. - Note that the ration at which the rotational speed of the
electric motor 123 and theelectric motor 133 may be a constant value at all times or a value which changes in accordance with pressures detected by thepressure gauge 145, thepressure gauge 146, thepressure gauge 147, thepressure gauge 148 and thepressure gauge 149. - Next, the operation of the electro-hydraulic actuation system according to the embodiment will be described.
- Note that since the operations of the
hydraulic motor 122 and the electro-hydraulic servo valve 127 are substantially similar to those of the conventional hydraulic motor and electro-hydraulic servo valve, the detailed description thereof will be omitted. - The
selector valve 141 selects the port where a working fluid supplied shows a maximum pressure of theport 141a which communicates with theport 127e of the electro-hydraulic servo valve 127 of the unit and theport 141b which communicates with the port 137c of the electro-hydraulic servo valve 137 of theunit 130 and then establishes a communication between the port so selected and theport 141c. - In other words, the
selector valve 141 selects a greater pressure of the pressure of the working fluid supplied to theport 127e of the electro-hydraulic servo valve 127 of theunit 120 or the load pressure of thehydraulic motor 122 of theunit 120 and the pressure of the working fluid supplied to theport 137e of the electro-hydraulic servo valve 137 of theunit 130 or the load pressure of thehydraulic motor 132 of theunit 130. - Since the
selector valve 141 selects a greater pressure of the load pressure of thehydraulic motor 122 of theunit 120 and the load pressure of thehydraulic motor 132 of theunit 130, the pressure of the working fluid supplied to theport 142d of the two-position valve 142 which communicates with theport 141c of theselector valve 141 via thethrottle 140a becomes the larger pressure of the load pressures of thehydraulic motor 122 and thehydraulic motor 132. - In addition, since the
port 142c of the two-position valve 142 communicates with the variable displacementhydraulic pump 111, the pressure of the working fluid supplied to theport 142c of the two-position valve 142 becomes the working fluid discharge pressure of the variable displacementhydraulic pump 111. - Then, the two-
position valve 142 takes thefirst position 142A where theport 142a which communicates with thetank 112 is made to communicate with theport 142e when the working fluid discharge pressure of the variable displacementhydraulic pump 111 becomes equal to or smaller than the pressure resulting from adding the predetermined set pressure by thespring 143 to the greater pressure of the load pressures of thehydraulic motor 122 and thehydraulic motor 132. - When the two-
position valve 142 takes thefirst position 142A, the pressure of the working fluid within thecylinder chamber 144b of the discharge volume changinghydraulic cylinder 144 which communicates with theport 142e of the two-position valve 142 via thethrottle 140b becomes the pressure of the working fluid within thetank 112. - Here, since the pressure of the working fluid within the
cylinder chamber 144b of the discharge volume changinghydraulic cylinder 144 which communicates with the variable displacementhydraulic pump 111 is the working fluid discharge pressure of the variable displacementhydraulic pump 111, in the discharge volume changinghydraulic cylinder 144, the pressure of the working fluid within thecylinder chamber 144a becomes smaller than the pressure of the working fluid within thecylinder chamber 144b, whereby the discharge volume changinghydraulic cylinder 144 retracts to thereby increase the discharge volume of the variable displacementhydraulic pump 111. - In addition, the two-
position valve 142 takes thesecond position 142B where theport 142b which communicates with the variable displacementhydraulic pump 111 is made to communicate with theport 142e when the working fluid discharge pressure of the variable displacementhydraulic pump 111 becomes greater than the pressure resulting from adding the predetermined set pressure by thespring 143 to the greater pressure of the load pressures of thehydraulic motor 122 of theunit 120 and thehydraulic motor 132 of theunit 130. - When the two-
position valve 142 takes thesecond position 142B, the pressure of the working fluid within thecylinder chamber 144a of the discharge volume changinghydraulic cylinder 144 becomes the working fluid discharge pressure of the variable displacementhydraulic pump 111. - Here, as has been described above, since the pressure of the working fluid within the
cylinder chamber 144b of the discharge volume changinghydraulic cylinder 144 is the working fluid discharge pressure of the variable displacementhydraulic pump 111, in the discharge volume changinghydraulic cylinder 144, the pressure of the working fluid within thecylinder chamber 144a becomes equal to or greater than the pressure of the working fluid within thecylinder chamber 144b, whereby the discharge volume changinghydraulic cylinder 144 extends to thereby decrease the discharge volume of the variable displacementhydraulic pump 111. - Thus, as has been described heretofore, the electro-
hydraulic actuation system 100 changes the working fluid discharge volume of the variable displacementhydraulic pump 111 so that a differential pressure between the greater pressure of the load pressures of thehydraulic motor 122 of theunit 120 and thehydraulic motor 132 of theunit 130 and the working fluid discharge pressure of the variable displacementhydraulic pump 111 becomes the predetermined set pressure by thespring 143. - Consequently, when there occurs no shortage in volume of working fluid supplied to the
hydraulic motor 122 of theunit 120 and thehydraulic motor 132 of theunit 130, a smallest pressure (hereinafter, referred to as a minimum differential pressure) of a differential pressure between a pressure detected by thepressure gauge 149 and a pressure detected by thepressure gauge 145, a differential pressure between the pressure detected by thepressure gauge 149 and a pressure detected by thepressure gauge 146, a differential pressure between the pressure detected by thepressure gauge 149 and a pressure detected by thepressure gauge 147, and a differential pressure between the pressure detected by thepressure gauge 149 and a pressure detected by thepressure gauge 148 becomes the predetermined set pressure by thespring 143. - Here, when there occurs even a slight shortage in volume of the working fluid supplied to the
hydraulic motor 122 of theunit 120 and thehydraulic motor 132 of theunit 130, the pressure detected by thepressure gauge 149 or the working fluid discharge pressure of the variable displacementhydraulic pump 111 decreases, the minimum differential pressure becomes smaller than the predetermined set pressure by thespring 143. - Consequently, by determining whether or not the minimum differential pressure becomes smaller than the predetermined set pressure by the
spring 143 based on pressures inputted from thepressure gauge 145, thepressure gauge 146, thepressure gauge 147, thepressure gauge 148 and thepressure gauge 149, the computer, not shown, can determine whether or not there occurs a shortage in volume of the working fluid supplied to either of thehydraulic motor 122 of theunit 120 and thehydraulic motor 132 of theunit 130. - Then, when the minimum differential pressure becomes smaller than the predetermined set pressure by the
spring 143, the computer, not shown, determines that there occurs a shortage in volume of the working fluid supplied to either of thehydraulic motor 122 of theunit 120 and thehydraulic motor 132 of theunit 130 and then decreases the rotational speed of theelectric motor 123 of theunit 120 and theelectric motor 133 of theunit 130 at substantially the same ratio relative to theelectric motor 123 and theelectric motor 133. - When the computer, not shown, decreases the rotational speed of the
electric motor 123 of theunit 120 and theelectric motor 133 of theunit 130 at substantially the same ratio relative to theelectric motor 123 and theelectric motor 133, a total volume of working fluid needed to be supplied to thehydraulic motor 122 of theunit 120 and thehydraulic motor 132 of theunit 130 is decreased, and the shortage of working fluid that is occurring in either of thehydraulic motor 122 of the unit and thehydraulic motor 132 of theunit 130 can be eliminated. - As has been described heretofore, since the electro-
hydraulic actuation system 100 can decrease the volume of the working fluid supplied to thehydraulic motor 122 of theunit 120 and thehydraulic motor 132 of theunit 130 at substantially the same ratio when there occurs a shortage in volume of working fluid supplied to thehydraulic motor 122 of theunit 120 and thehydraulic motor 132 of theunit 130, the occurrence of a shortage in volume of working fluid supplied to the hydraulic motor having a larger load pressure of thehydraulic motor 122 of theunit 120 and thehydraulic motor 132 of theunit 130 can be prevented. - In addition, since the electro-
hydraulic actuation system 100 can decrease the volume of the working fluid supplied to thehydraulic motor 122 of theunit 120 and thehydraulic motor 132 of theunit 130 at substantially the same ratio, for example, in a case where thehydraulic motor 122 of theunit 120 is used for a right side caterpillar of a hydraulic shovel and thehydraulic motor 132 of theunit 130 is used for a left side caterpillar of the hydraulic shovel, when the operator attempts to move the hydraulic shove straight forward by inputting substantially the same operation amounts into theunit 120 and theunit 130, even in case a load borne by the right side caterpillar becomes larger than a load borne by the left side caterpillar due to the right side caterpillar riding on a stone or the left side caterpillar entering a puddle, the movement of the right side caterpillar and the movement of the left side caterpillar can be made slower at substantially the same ratio. - Consequently, since the moving direction of the hydraulic shovel provided with the electro-
hydraulic actuation system 100 is maintained while the moving speed thereof gets slower, a risk of a hydraulic shovel moving in a direction different from the direction intended by the operator can be prevented, which is the case with a hydraulic shovel provided with the conventional hydraulic actuation system 900 (refer to Fig. 22). - Firstly, the configuration of an electro-hydraulic actuation system according to a second embodiment will be described.
- As shown in Figs. 8 and 9, since an electro-
hydraulic actuation system 300 as an electro-hydraulic actuation system according to the second embodiment has a substantially similar configuration to that of the electro-hydraulic actuation system (refer to Fig. 1) according to the first embodiment, hereinafter, like reference numerals are imparted to constituent parts of the electro-hydraulic actuation system 300 which are substantially like to those of the electro-hydraulic actuation system 100 and the detailed description thereof will be omitted. - Instead of the unit 120 (refer to Fig. 1) and the unit 130 (refer to Fig. 1) of the electro-hydraulic actuation system 100 (refer to Fig. 1), the electro-
hydraulic actuation system 300 includes an electro-hydraulic actuator 320 (refer to Figs. 10 to 14) and aunit 330, the detailed description of which will be omitted, having a similar configuration to that of theunit 320. - Instead of the hydraulic motor 122 (refer to Fig. 1) of the unit 120 (refer to Fig. 1), the
unit 320 has a variable displacementhydraulic motor 322 as a hydraulic actuator having formed therein aport 322a and aport 322b which are made to communicate with a variable displacementhydraulic pump 111 or atank 112 and adapted to impart a driving force toreduction gears 121 by virtue of the pressure of a working fluid supplied to theport 322a and theport 322b. - Here, the variable displacement
hydraulic motor 322 has, as shown in Figs. 10 to 14, abox body 351, abox body 152 fixed to thebox body 351, aswash plate 153, amotor shaft 154, abearing 355 for rotatably supporting themotor shaft 154 on thebox body 351, abearing 156, acylinder bock 157 having formed therein a plurality ofcylinder chambers 157a, a plurality ofpistons 158,shoe members 159, aspring 160 and aseal 162. - In addition, instead of the electro-hydraulic servo valve 127 (refer to Fig. 1) of the unit 120 (refer to Fig. 1), the
unit 320 has, as shown in Figs. 8 and 9, an electro-hydraulic servo valve 327 as a fluid volume changing valve having formed therein aport 327a which communicates with the variable displacementhydraulic pump 111, apart 327b which communicates with thetank 112, aport 327c which communicates with theport 322a of the variable displacementhydraulic motor 322, apart 327d which communicates with theport 322b of the variable displacementhydraulic motor 322, aport 327e and aport 327f, adapted to take any of afirst position 327A, asecond position 327B and athird position 328C based on the rotating amount of a secondtoothed shaft 125 and the driving amount of anelectric motor 123 and adapted to change the volume of a working fluid discharged by the variable displacementhydraulic pump 111 for supply to the variable displacementhydraulic motor 322. - Note that the
first position 327A is a position where theport 327a is made to communicate with theport 327c and theport 327e and a communication of theport 327b with theport 327d and theport 327f is established, thesecond position 327B is a position where the communication with theport 327a, theport 327b, theport 327c, theport 327d, theport 327e and theport 327f is cut off, and thethird position 327C is a position where theport 327a is made to communicate with theport 327d and theport 327f and a communication of theport 327d with theport 327c and theport 327e is established. - Here, as shown in Figs. 10 to 14, the electro-
hydraulic servo valve 327 has abox body 151, a movingbody 171 for changing the communication of theport 327a, theport 327b, theport 327c, theport 327d, theport 327e and theport 327f, abearing 172 for transmitting an axial movement of the secondtoothed shaft 125 to the movingbody 171 and acap 173, acap 174 and aseal 175 which prevent the leakage of a working fluid from the inside to the outside of thebox body 151. - Note that the
unit 320 has abearing 361 and abearing 362 which rotatably support a firsttoothed shaft 124 relative to thebox body 151. - In addition, as shown in Figs. 8 and 9, the
unit 320 has a loadpressure selector valve 328 having formed therein aport 328a which communicates with theport 327c of the electro-hydraulic servo valve 327, aport 328b which communicates with theport 327d of the electro-hydraulic servo valve 327, apart 328c which communicates with theport 327e of the electro-hydraulic servo valve 327, aport 328d which communicates with theport 327f of the electro-hydraulic servo valve 327, aport 328e which communicates with thetank 112 and aport 328f which communicates with aport 141a of aselector valve 141, adapted to take any of thefirst position 328A, thesecond position 328B and thethird position 328C based on the pressure of a working fluid supplied to theport 328c and theport 328d and adapted to make either of theport 328a and theport 328b to which a working fluid having a greater pressure is supplied communicate with theport 328e for selection of the load pressure of the variable displacementhydraulic motor 322. - Note that the
first position 328A is a position where theport 328a is made to communicate with theport 328f and the communication between theport 328b and theport 328e is cut off, thesecond position 328B is a position where the communication of theport 328a and theport 328b is cut off and theport 328e is made to communicate with theport 328f, and thethird position 328C is a position where the communication of theport 328a and theport 328e are cut off and theport 328b is made to communicate with theport 328f. - Here, the load
pressure selector valve 328 has, as shown in Figs. 10 to 14, thebox body 151, a movingbody 371 for changing the communication of theport 328a, theport 328b, theport 328c, theport 328d, theport 328e and theport 328f, aspring 329a for biasing the movingbody 371 so that the movingbody 371 is located at afirst position 328A (refer to Fig. 9), aspring 329b for biasing the movingbody 371 so that the moving body is located at athird position 328C (refer to Fig. 9) and acap 372 and acap 373 which prevent the leakage of the working fluid from the inside to the outside of thebox body 151. - Note that the electro-
hydraulic servo valve 327 of theunit 320, the loadpressure selector valve 328, an electro-hydraulic servo valve 337 of theunit 330, a loadpressure selector valve 338, aselector valve 141, aspring 142 and a discharge volume changinghydraulic cylinder 144 constitutes a discharge volume changing means for changing the working fluid discharge volume of the variable displacementhydraulic pump 111 based on a maximum pressure of pressures of the working fluid supplied to the variable displacementhydraulic motor 322 of theunit 320 and a variable displacementhydraulic motor 332 of theunit 330 and the working fluid discharge pressure of the variable displacementhydraulic pump 111. - Next, the operation of the electro-hydraulic actuation system according to the embodiment will be described.
- Note that the detailed description of those of operations of the electro-
hydraulic actuation system 300 according to the embodiment will be omitted which are substantially similar to the operations of the electro-hydraulic actuation system 100 (refer to Fig. 1) according to the first embodiment. - The load
pressure selector valve 328 takes thefirst position 328A where a communication of theport 328a and theport 328f is established when the pressure of the working fluid supplied to theport 328c is greater than the pressure of the working fluid supplied to theport 328d, and takes asecond position 328B when the pressure of the working fluid supplied to theport 328c is the same as the pressure of the working fluid supplied to theport 328d, and takes thethird position 328C where a communication of theport 328b and theport 328f is established when the pressure of the working fluid supplied to theport 328c is smaller than the pressure of the working fluid supplied to theport 328d. - In addition, the electro-
hydraulic servo valve 327 allows theport 327c which communicates with theport 328a of the loadpressure selector valve 328 to communicate with theport 327e which communicates with theport 328c of the loadpressure selector valve 328 when the electro-hydraulic servo valve 327 makes theport 327a which communicates with the variable displacementhydraulic pump 111 or theport 327b which communicates with thetank 112 communicate with theport 327c, and allows theport 327d which communicates with theport 328d of the loadpressure selector valve 328 to communicate with theport 327f which communicates with theport 328d of the loadpressure selector valve 328 when the electro-hydraulic servo valve 327 makes theport 327a or theport 327b communicate with theport 327d. - Consequently, the pressure of the working fluid supplied to the
port 328f of the loadpressure selector valve 328 or the pressure of the working fluid supplied to aport 141a of theselector valve 141 becomes the load pressure of the variable displacementhydraulic motor 322 of theunit 320. - Similarly, the pressure of a working fluid supplied to a
port 338f of the loadpressure selector valve 338 or the pressure of a working fluid supplied to aport 141b of theselector valve 141 becomes the load pressure of the variable displacementhydraulic motor 332 of theunit 330. - Since the pressure of the working fluid supplied to the
port 141a of theselector valve 141 becomes the load pressure of the variable displacementhydraulic motor 322 of theunit 320 and the pressure of the working fluid supplied to theport 141b of theselector valve 141 becomes the load pressure of the variable displacementhydraulic motor 332 of theunit 330, as has been described in the first embodiment, the electro-hydraulic actuation system 300 can change the working fluid discharge volume of the variable displacementhydraulic pump 111 so that a differential pressure between a larger load pressure of the load pressures of the variable displacementhydraulic motor 322 of theunit 320 and the variable displacementhydraulic motor 332 of theunit 330 and the working fluid discharge pressure of the variable displacementhydraulic pump 111 becomes a predetermined set pressure by thespring 143. - Firstly, the configuration of an electro-hydraulic actuation system according to a third embodiment will be described.
- As shown in Figs. 15 and 16, since an electro-
hydraulic actuation system 500 as an electro-hydraulic actuation system according to the embodiment has a configuration which is substantially similar to that of the electro-hydraulic actuation system 100 (refer to Fig. 1) according to the first embodiment or the electro-hydraulic actuation system 300 (refer to Fig. 8) according to the second embodiment, hereinafter, like reference numerals are imparted to constituent parts of the electro-hydraulic actuation system 500 which are substantially like to those of the electro-hydraulic actuation system 100 or the electro-hydraulic actuation system 300, and the detailed description thereof will be omitted. - The electro-
hydraulic actuation system 500 includes, as electro-hydraulic actuators, a unit 520 (refer to Figs. 17 to 20) and aunit 530, the detailed description of which will be omitted, having a similar configuration to that of theunit 520, instead of the unit 120 (refer to Fig. 1) and the unit 130 (refer to Fig. 1) of the electro-hydraulic actuation system 100 (refer to Fig. 1). - The
unit 520 has, instead of the electro-hydraulic servo valve 127 of the unit 120 (refer to Fig. 1), an electro-hydraulic servo valve 527 as a fluid volume changing valve having formed therein aport 527a which communicates with a variable displacementhydraulic pump 111, aport 527b which communicates with atank 112, aport 527c which communicates with aport 122a of ahydraulic motor 122 and aport 527d which communicates with aport 122b of thehydraulic motor 122, adapted to take any of afirst position 527A, asecond position 527B and athird position 527C based on the rotating amount of a secondtoothed shaft 125 and the driving amount of anelectric motor 123 and adapted to change the volume of a working fluid discharged by the variable displacementhydraulic pump 111 for supply to thehydraulic motor 122. - Note that the
first position 527A is a position where theport 527a is made to communicate with theport 527c, and theport 527b is made to communicate with theport 527d, thesecond position 527B is a position where the communication of theport 527a, theport 527b, theport 527c and theport 527d is cut off, and thethird position 527C is a position where theport 527a is made to communicate with theport 527d, and theport 527b is made to communicate with theport 527c. - Here, as shown in Figs. 17 to 20, the electro-
hydraulic servo valve 527 has abox body 151, a movingbody 171 for changing the communication of theport 527a, theport 527b, theport 527c and theport 527d, abearing 172 for transmitting an axial movement of the secondtoothed shaft 125 to the movingbody 171 and acap 173, acap 174 and aseal 175 which prevent the leakage of a working fluid from the inside to the outside of thebox body 151. - In addition, as shown in Fig.15, the electro-
hydraulic actuation system 500 includes a two-positionelectromagnetic valve 514 having formed therein aport 514a which communicates with arelief valve 113 and aport 514b which communicates with thetank 112 and adapted to take either of afirst position 514A where the communication of theport 514a and theport 514b is cut off based on a signal inputted and asecond position 514B where the communication of theport 514a and theport 514b is established. - In addition, instead of the selector valve 141 (refer to Fig. 1 or 8) of the electro-hydraulic actuation system 100 (refer to Fig. 1) or the electro-hydraulic actuation system 300 (refer to Fig. 8), the electro-
hydraulic actuation system 500 includes apressure setting valve 545 for setting a pressure for a working fluid supplied to aport 142d of a two-position valve 142 by being switched between a position where a working fluid discharged by the variable displacementhydraulic pump 111 is led to theport 142d of the two-position valve 142 via athrottle 140a and a position where the working fluid discharged by the variable displacement hydraulic pump 11 is led to thetank 112 based on the pressure of the working fluid supplied to theport 142d of the two-position valve 142 and a signal inputted via asignal wire 545a. - Additionally, a computer, not shown, of the electro-
hydraulic actuation system 500 is configured to receive pressures detected by apressure gauge 145, apressure gauge 146, apressure gauge 147, apressure gauge 148 and apressure gauge 149 for input thereinto, change the rotational speed of theelectric motor 123 of theunit 520 and anelectric motor 133 of theunit 530 at substantially the same ratio relative to theelectric motor 123 and theelectric motor 133 based on the pressures so inputted, produce a signal based on the inputted pressures and input the signal so produced into the two-positionelectromagnetic valve 514. - Furthermore, the computer, not shown, is configured to select a driving side pressure while following the motor rotating direction of the
hydraulic motors pressure gauge 145, thepressure gauge 146, thepressure gauge 147 and thepressure gauge 148, select a greatest pressure of the pressures of thehydraulic motor 122 and thehydraulic motor 132 and input the pressure so selected into thepressure setting valve 545 as a signal via thesignal wire 545a. - Here, the
pressure gauge 145, thepressure gauge 146, thepressure gauge 147, thepressure gauge 148, thepressure gauge 149, the computer, not shown, thepressure setting valve 545, the two-position valve 142, aspring 143 and a discharge volume changinghydraulic cylinder 144 constitutes a discharge volume changing means for changing the working fluid discharge volume of the variable displacementhydraulic pump 111 based on the greatest pressure of the pressures of the working fluid supplied to thehydraulic motor 122 of theunit 520 and thehydraulic motor 132 of theunit 530 and the working fluid discharge pressure of the variable displacementhydraulic pump 111. - Next, the operation of the electro-hydraulic actuation system according to the embodiment will be described.
- Note that the detailed description of those of operations of the electro-
hydraulic actuation system 500 according to the embodiment will be omitted which are substantially similar to the operations of the electro-hydraulic actuation system 100 (refer to Fig. 1) according to the first embodiment. - The computer, not shown, selects a driving side pressure while following the motor rotating direction of the
hydraulic motors pressure gauge 145, thepressure gauge 146, thepressure gauge 147 and thepressure gauge 148, selects a greatest pressure of the pressures of thehydraulic motor 122 and thehydraulic motor 132 and inputs the pressure so selected into thepressure setting valve 545 as a signal via thesignal wire 545a. - When the signal is inputted thereinto by the computer, not shown, the
pressure setting valve 545 produces a force in accordance with the signal so inputted and changes positions based on the force so produced and the pressure of the working fluid supplied to theport 142d of the two-position valve 142. - To be specific, when the force produced in accordance with the signal inputted is greater than a force produced by virtue of the pressure of the working fluid supplied to the
port 142d of the two-position valve 142, thepressure setting valve 545 is switched to a position where the working fluid discharged by the variable displacementhydraulic pump 111 is led to theport 142d of the two-position valve 142 via thethrottle 140a and when the force produced in accordance with the signal inputted is equal to or smaller than the force produced by virtue of the pressure of the working fluid supplied to theport 142d of the two-position valve 142, thepressure setting valve 545 is switched to a position where the working fluid discharged by the variable displacementhydraulic pump 111 is led to thetank 112. - Here, the
pressure setting valve 545 is configured to produce a force which allows the computer, not shown, to implement a feedback using the pressure from thepressure gauge 149 so that the pressure of the working fluid supplied to theport 142d of the two-position valve 142 becomes a sum of the pressure selected from thehydraulic motor 122 of theunit 520 and thehydraulic motor 132 of theunit 530 and a pressure allowance that is determined in advance. - Consequently, the pressure of the working fluid supplied to the
port 142d of the two-position valve 142 becomes substantially the same as the sum of the pressure selected from thehydraulic motor 122 of theunit 520 and thehydraulic motor 132 of theunit 530 and the pressure allowance that is determined in advance, and as has been described in the first embodiment, the electro-hydraulic actuation system 500 can change the working fluid discharge volume of the variable displacementhydraulic pump 111 so as to become the sum of the greater pressure of the pressures of thehydraulic motor 122 of theunit 520 and thehydraulic motor 132 of theunit 530 and the pressure allowance that is determined in advance. - In addition, as has been described in the first embodiment, when determining that there has occurred a shortage in volume of the working fluid supplied to either of the
hydraulic motor 122 of theunit 520 and thehydraulic motor 132 of theunit 530 based on the pressures inputted from thepressure gauge 145, thepressure gauge 146, thepressure gauge 147, thepressure gauge 148 and thepressure gauge 149, the computer, not shown, generates a signal which locates the two-positionelectromagnetic valve 514 at thefirst position 514A and inputs the signal so generated into the two-positionelectromagnetic valve 545. - When the two-position
electromagnetic valve 514 is located at thefirst position 514A in response to the signal inputted from the computer, not shown, since the set pressure of therelief valve 113 becomes largest within a designed range, the pressure of the working fluid discharged by the variable displacementhydraulic pump 111 for supply to theunit 520 and theunit 530 can be increased to a set pressure of therelief valve 113 which is greatest within the designed range. - In addition, as has been described in the first embodiment, when determining that there has occurred a shortage in volume of the working fluid supplied to either of the
hydraulic motor 122 of theunit 520 and thehydraulic motor 132 of theunit 530 based on the pressures inputted from thepressure gauge 145, thepressure gauge 146, thepressure gauge 147, thepressure gauge 148 and thepressure gauge 149, the computer, not shown, reduces the rotational speed of theelectric motor 123 and theelectric motor 133 at the same or a predetermined ratio, thereby making it possible to prevent a state in which the volume of working fluid is short. - In addition, when determining that there is occurring no shortage in volume of the working fluid supplied to the
hydraulic motor 122 of theunit 520 and thehydraulic motor 132 of theunit 530 based on the pressures inputted from thepressure gauge 145, thepressure gauge 146, thepressure gauge 147, thepressure gauge 148 and thepressure gauge 149, the computer, not shown, produces a signal which locates the two-positionelectromagnetic valve 514 at thesecond position 514B and inputs the signal so produced to the two-positionelectromagnetic valve 514. - When the two-position
electromagnetic valve 514 is located at thesecond position 514B in response to the signal inputted from the computer, not shown, since the set pressure of therelief valve 113 becomes smallest within the designed range, the pressure of the working fluid discharged by the variable displacementhydraulic pump 111 for supply to theunit 520 and theunit 530 can only be increased to a set pressure of therelief valve 113 which is smallest within the designed range. - Consequently, when there is occurring no shortage in volume of the working fluid supplied to the
hydraulic motor 122 of theunit 520 and thehydraulic motor 132 of theunit 530, the electro-hydraulic actuation system 500 can suppress the pressure of working fluid discharged by the variable displacementhydraulic pump 111 for supply to theunit 520 and theunit 530 to the set pressure of therelief valve 113 which is the smallest within the designed range or smaller and can reduce energy consumed by the variable displacementhydraulic pump 111 when compared with a case where the two-positionelectromagnetic valve 514 is provided. In addition, in a state where the rotational speed inputted is 0, the computer, not shown, outputs to thepressure setting valve 545 a signal which makes the discharge pressure of the variable displacementhydraulic pump 111 become a predetermined low pressure based on the pressure of thepressure gauge 149, thereby making it possible to reduce energy consumed. Additionally, in the state where the rotational speed inputted is 0, the computer, not shown, outputs to thepressure setting valve 545 a signal which makes the discharge pressure of the variable displacementhydraulic pump 111 become a predetermined low pressure based on the pressure of thepressure gauge 149, thereby making it possible to reduce energy consumed. - Firstly, the configuration of an electro-hydraulic actuation system according to a fourth embodiment will be described.
- As shown in Fig. 21, since an electro-
hydraulic actuation system 600 as an electro-hydraulic actuation system according to the embodiment has a substantially similar configuration to that of the electro-hydraulic actuation system 500 (refer to Fig. 15) according to the third embodiment, hereinafter, like reference numerals are imparted to constituent parts of the electro-hydraulic actuation system 600 which are substantially like to those of the electro-hydraulic actuation system 500. - The electro-
hydraulic actuation system 600 includes, instead of the two-position electromagnetic valve 514 (refer to Fig. 15) of the electro-hydraulic actuation system 500 (refer to Fig. 15), a two-positionelectromagnetic valve 614 having formed therein aport 614a which communicates with a variable displacementhydraulic pump 111, aunit 520 and aunit 530, aport 614b which communicates with atank 112 and aport 614c which communicates with arelief valve 113 and adapted to take based on a signal inputted either of a first position where the communication of theport 614a and theport 614b is established and a second position where the communication of theport 614a and theport 614c is established. - In addition, a computer, not shown, of the electro-
hydraulic actuation system 600 is configured to receive pressures detected by apressure gauge 145, apressure gauge 146, apressure gauge 147, apressure gauge 148 and apressure gauge 149 for input thereinto, produce a signal based on the pressures inputted and input the signal produced into the two-positionelectromagnetic valve 614. - Next, the operation of the electro-
hydraulic actuation system 600 according to the invention will be described. - Note that the detailed description of those of operations of the electro-
hydraulic actuation system 600 will be omitted which are substantially similar to the operations of the electro-hydraulic actuation system 500 (refer to Fig. 15) according to the third embodiment. - As has been described in the first embodiment, when determining that there has occurred a shortage in volume of the working fluid supplied to either of the
hydraulic motor 122 of theunit 520 and thehydraulic motor 132 of theunit 530 based on the pressures inputted from thepressure gauge 145, thepressure gauge 146, thepressure gauge 147, thepressure gauge 148 and thepressure gauge 149, the computer, not shown, generates a signal which locates the two-positionelectromagnetic valve 614 at thesecond position 614B and inputs the signal so generated into the two-positionelectromagnetic valve 614. - When the two-position
electromagnetic valve 614 takes thesecond position 614B in response to the signal inputted from the computer, not shown, since theport 614a which communicates with the variable displacementhydraulic pump 111, theunit 520 and theunit 530 communicates with theport 614c which communicates with therelief valve 113, the pressure of a working fluid discharged by the variable displacementhydraulic pump 111 for supply to theunit 520 and theunit 530 can be increased to a set pressure for therelief valve 113. - In addition, when determining that there is occurring no shortage in volume of the working fluid supplied to the
hydraulic motor 122 of theunit 520 and thehydraulic motor 132 of theunit 530 based on the pressures inputted from thepressure gauge 145, thepressure gauge 146, thepressure gauge 147, thepressure gauge 148 and thepressure gauge 149, the computer, not shown, generates a signal which locates the two-positionelectromagnetic valve 614 at the first position 614A and inputs the signal so generated into the two-positionelectromagnetic valve 614. - When the two-position
electromagnetic valve 614 takes the first position 614A in response to the signal inputted from the computer, not shown, since theport 614a which communicates with the variable displacementhydraulic pump 111, theunit 520 and theunit 530 communicates with theport 614b which communicates with thetank 112, the pressure of the working fluid discharged by the variable displacementhydraulic pump 111 for supply to theunit 520 and theunit 530 is reduced when compared to the case where the two-positionelectromagnetic valve 614 takes thesecond position 614B. - Consequently, the electro-
hydraulic actuator system 600 can suppress the pressure of the working fluid discharged by the variable displacementhydraulic pump 111 for supply to theunit 520 and theunit 530 when there is occurring no shortage in volume of the working fluid supplied to thehydraulic motor 122 of theunit 520 and thehydraulic motor 132 of theunit 530 to a smaller value when compared with when there is occurring a shortage in volume of the working fluid supplied to thehydraulic motor 122 of theunit 520 and thehydraulic motor 132 of theunit 530 and can reduce energy consumed by the variable displacementhydraulic pump 111 when compared with a case where the two-positionelectromagnetic valve 614 is not provided. - As has been described heretofore, the liquid pump according to the invention is a liquid pump for discharging a liquid from a liquid storage portion to at least one predetermined position and is configured to have at least one cylinder chamber formed for induction of the liquid thereinto from the liquid storage portion, a piston disposed in the cylinder chamber, a liquid discharge port formed in the cylinder chamber and a driving means for driving the piston so as to drive, in turn, a cylinder in axial directions within the cylinder chamber. By this configuration, for example, it can be ensured that a required constant and minute volume of lubricating oil is supplied to bearings and gears, the heat generation at the supply points can be suppressed, and the power consumed by the apparatus can be suppressed to a lower level.
- In the liquid pump according to the invention, the piston is inserted from one end portion of the cylinder chamber, and the liquid discharge port is disposed at the other end portion of the cylinder chamber. By adopting the configuration like this, a minute volume of liquid can be discharged, the discharge amount can be adjusted finely, the pump can instantaneously be stopped to stop the flow of the liquid, and the operation can be controlled so as to enable the intermittent discharge of the liquid.
- In the liquid pump according to the invention, a pair of cylinder chambers is disposed at both ends of the piston, a piston is inserted from one end of each cylinder chamber, and a liquid discharge port is opened in the other end of each cylinder chamber.
- By adopting the configuration like this, liquid can be supplied to two locations per one piston.
- In the liquid pump according to the invention, in the piston and the cylinder chamber, the cross-sectional shape and/or length is optimized in accordance with the supply volume of liquid. By adopting the configuration like this, the volume of fluid supplied can be adjusted even in case the operation frequency of the piston is identical. In addition, even in case the plurality of cylinder chambers and the pistons are operated at the same frequency, the supply volume of fluid per cylinder chamber can be altered.
- In the liquid pump according to the invention, the piston is inserted into the cylinder chamber, and a single or a plurality of liquid discharge ports are formed in the cylinder chamber. By adopting the configuration like this, liquid can be supplied to a plurality of locations or two or more locations per piston.
- In the liquid pump according to the invention, a construction is adopted in which a single or a plurality of stepped portions are formed in the cylinder chamber, the piston is formed so as to have a substantially equal shape to that of the cylinder chamber, and a liquid discharge port is disposed at the single or each of the plurality of stepped portions formed in the cylinder chamber. By adopting the configuration like this, liquid can be supplied to a plurality of locations or two or more locations per piston with the simple construction.
- In the liquid pump according to the invention, the single or the plurality of stepped portions in the cylinder chamber are formed in such a manner as to be substantially symmetrical in the axial direction, the piston is formed into a substantially equal shape to the formation of the substantially symmetrical stepped portions, and a liquid discharge port is formed in the single or each of the plurality of stepped portions formed in the cylinder chamber. By adopting the configuration like this, liquid can be supplied to a plurality of locations or two or more locations per piston with the simple construction.
- In the liquid pump according to the invention, a member is disposed for forming the single or the plurality of stepped portions substantially symmetrically in the cylinder chamber. By adopting the configuration like this, after the piston having the symmetrical stepped portions is inserted into the cylinder chamber, the member for forming the substantially symmetrical stepped portions is disposed, whereby the assembly can be facilitated.
- In the liquid pump according to the invention, as to the shape of a liquid reservoir defined between the cylinder chamber and the piston, the relative axial length of the cylinder chamber and the piston and/or cross sectional areas thereof which are normal to their axes are optimized in accordance with the volume of liquid supplied. By adopting the configuration like this, even in case the operation frequency of the piston is identical, the volume of fluid supplied can be adjusted. In addition, even in case the plurality of cylinder chambers and the pistons are operated at the same frequency, the supply volume of fluid per cylinder chamber can be altered.
- In the liquid pump according to the invention, a liquid bleeder hole is provided in the cylinder chamber. By adopting the configuration like this, a liquid stored between the end portion of the piston and the cylinder chamber can be removed, when the piston is driven, so that the motion of the piston is not disturbed.
- In the liquid pump according to the invention, a plurality of constructions are disposed in series in which a single or a plurality of stepped portions are formed in a hollow portion of the cylinder chamber and a cross-sectional area of each stepped portion which is normal to the axis thereof is gradually increased as it extends along the axial direction thereof. By adopting the configuration like this, liquid can be supplied to a plurality of locations or two or more locations per piston with the simple construction.
- In the liquid pump according to the invention, the piston and the cylinder chamber are provided in a plural number for a single driving means. By adopting the configuration like this, there is no need to provide a plurality of driving means for moving the pluralities of pistons and cylinder chambers, thereby making it possible to reduce the number of components.
- In the liquid pump according to the invention, the driving means is made up of a solenoid which is made up of, in turn, a shaft portion which is wholly or partially made of a magnetic material and a solenoid coil which are adapted to move relative to each other, the shaft portion and the solenoid coil are separated by a bulkhead so that the shaft portion and the solenoid coil are not in contact with each other, and the shaft portion and the piston are made to interlock with each other by a predetermined connecting means. By adopting the configuration like this, even in the event that the shaft portion and the piston, which are driving portions of the liquid pump, is submerged in a liquid within a completely sealed space, since the shaft portion and the piston can be operated in a non-contact fashion by the solenoid coil from the outside, the leakage of liquid from the liquid piston pump can be prevented. Namely, by the invention, a rotating shaft of a rotary pump is eliminated, and rotary and sliding motions at an 0 ring for separating the liquid from the external atmosphere and a shaft seal portion are eliminated, whereby it is possible to eliminate the possibility of leakage of liquid from the shaft portion or intrusion of air into a lubricating path when the lubricating path is in a vacuum state.
- In the liquid pump according to the invention, a bulkhead made of a non-magnetic material is used for the bulkhead. By adopting the configuration like this, a magnetic field produced in the solenoid coil is allowed to pass only a plunger made of a magnetic material, thereby making it possible to increase an attractive force between the plunger and a base.
- In the liquid pump according to the invention, the solenoid is used as the driving means, and furthermore, the liquid pump is used as a lubricating oil circulating pump, whereby portions needing lubrication and lubricating paths, and a lubricating oil discharge main part of the lubricating oil circulating pump are sealed. By adopting the configuration like this, the portions where lubricating oil is circulated and the piston, which is a sliding part of the lubricating oil circulating pump, and the driving portion therefor can be sealed, whereby no seal is needed at portions where sliding or/and rotating motions occur, thereby making it possible to reduce the possibility of lubricating oil leakage. In particular, the lubricating oil circulating portion resides in a vacuum, it is possible to eliminate as much as possible a concern that outside air intrudes from seals at the sliding or/and rotating portions to thereby deteriorate the degree of vacuum.
- In the liquid pump according to the invention, in an apparatus having rotating portions needing lubricating oil for lubrication of bearings, a lubricating storage tank for storing lubricating oil, which is in communication for induction of the lubricating oil thereinto, is formed, and a lubricating oil supply pump and supply paths are disposed in the apparatus having rotating portions for supplying the oil from the lubricating oil storage tank to predetermined portions such as the bearings and gears. By adopting the configuration like this, the necessity of rotating shafts and gears being submerged in the lubricating oil is obviated, whereby the resistance can be reduced which would occur when the apparatus is driven, thereby making it possible to attain saving energy. As the apparatus having the configuration, there are raised rotary vacuum pumps and reduction gears.
- The apparatus having rotating portions according to the invention is characterized in that the main part for discharging a lubricating oil of the lubricating oil supply pump is formed integrally in the lubricating oil storage tank. By adopting the configuration like this, there is no need to provide a means for supplying a lubricating oil to the lubricating oil supply pump, and furthermore, a space where the lubrication oil supply pump is disposed can also be reduced.
- In the apparatus having rotating portions according to the invention, the lubricating oil storage tank is disposed at a position where the lubricating oil in the apparatus having rotating portions flows into by virtue of its own gravity. By adopting this configuration, there is no need to provide a complex means for returning the lubricating oil to the lubricating oil storage tank.
- In the apparatus having rotating portions according to the invention, the liquid pumps set forth in Claims 1 to 15 are used as the pump. By adopting this configuration, a simple and easy construction can be attained.
Claims (1)
- An electro-hydraulic actuation system being characterized by comprising a pump, a plurality of electro-hydraulic actuators each having an electric motor, a hydraulic actuator and a fluid volume changing valve for changing the volume of a fluid discharged by the pump based on driving amounts of the electric motor and the hydraulic actuator for supply to the hydraulic actuator, discharge volume changing means for changing the volume of the fluid discharged by the pump based on a maximum pressure of pressures of the fluid supplied to the hydraulic actuators of the plurality of electro-hydraulic actuators and the discharge pressure of the fluid discharged by the pump, and rotational speed changing means for changing the rotational speed of the electric motors of the plurality of electro-hydraulic actuators at substantially the same ratio relative to the electric motors of the plurality of electro-hydraulic actuators based on a maximum pressure of pressures of the fluid supplied to the hydraulic actuators of the plurality of electro-hydraulic actuators and the discharge pressure of the fluid discharged by the pump.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2002202792 | 2002-07-11 | ||
JP2002202792 | 2002-07-11 | ||
PCT/JP2003/008865 WO2004007973A1 (en) | 2002-07-11 | 2003-07-11 | Electrohydraulic actuation system |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1553308A1 true EP1553308A1 (en) | 2005-07-13 |
Family
ID=30112646
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP03741367A Withdrawn EP1553308A1 (en) | 2002-07-11 | 2003-07-11 | Electrohydraulic actuation system |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP1553308A1 (en) |
JP (1) | JPWO2004007973A1 (en) |
AU (1) | AU2003280997A1 (en) |
WO (1) | WO2004007973A1 (en) |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3546336A1 (en) * | 1985-12-30 | 1987-07-02 | Rexroth Mannesmann Gmbh | CONTROL ARRANGEMENT FOR AT LEAST TWO HYDRAULIC CONSUMERS SUPPLIED BY AT LEAST ONE PUMP |
JPH076521B2 (en) * | 1987-06-30 | 1995-01-30 | 日立建機株式会社 | Load sensing hydraulic drive circuit controller |
DE3943357A1 (en) * | 1989-12-29 | 1991-07-04 | Rexroth Mannesmann Gmbh | CIRCUIT ARRANGEMENT WITH A CONTROL ELECTRONICS FOR THE MAGNETIC COILS OF ACTUATORS OF A HYDRAULIC SYSTEM |
JPH04290603A (en) * | 1991-03-19 | 1992-10-15 | Kayaba Ind Co Ltd | Hydraulic controller |
CA2201626A1 (en) * | 1995-10-09 | 1997-04-09 | Shin Caterpillar Mitsubishi Ltd. | Control apparatus for construction machine |
JP2001065501A (en) * | 1999-09-01 | 2001-03-16 | Teijin Seiki Co Ltd | Hydraulic driving device |
US6439101B1 (en) * | 1999-10-13 | 2002-08-27 | Teijin Seiki Co., Ltd. | Electro-hydraulic servomotor |
-
2003
- 2003-07-11 JP JP2004521200A patent/JPWO2004007973A1/en active Pending
- 2003-07-11 WO PCT/JP2003/008865 patent/WO2004007973A1/en active Application Filing
- 2003-07-11 AU AU2003280997A patent/AU2003280997A1/en not_active Abandoned
- 2003-07-11 EP EP03741367A patent/EP1553308A1/en not_active Withdrawn
Non-Patent Citations (1)
Title |
---|
See references of WO2004007973A1 * |
Also Published As
Publication number | Publication date |
---|---|
JPWO2004007973A1 (en) | 2005-11-10 |
AU2003280997A1 (en) | 2004-02-02 |
WO2004007973A1 (en) | 2004-01-22 |
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