GB2359592A - Hydraulic controller - Google Patents

Hydraulic controller Download PDF

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Publication number
GB2359592A
GB2359592A GB0104782A GB0104782A GB2359592A GB 2359592 A GB2359592 A GB 2359592A GB 0104782 A GB0104782 A GB 0104782A GB 0104782 A GB0104782 A GB 0104782A GB 2359592 A GB2359592 A GB 2359592A
Authority
GB
United Kingdom
Prior art keywords
variable opening
control valve
opening unit
directional control
pressure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB0104782A
Other versions
GB0104782D0 (en
GB2359592B (en
Inventor
Satoshi Matsumoto
Takashi Shinke
Shigeru Nakayama
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shibaura Machine Co Ltd
Original Assignee
Toshiba Machine Co Ltd
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Filing date
Publication date
Application filed by Toshiba Machine Co Ltd filed Critical Toshiba Machine Co Ltd
Publication of GB0104782D0 publication Critical patent/GB0104782D0/en
Publication of GB2359592A publication Critical patent/GB2359592A/en
Application granted granted Critical
Publication of GB2359592B publication Critical patent/GB2359592B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
    • F15B11/05—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed specially adapted to maintain constant speed, e.g. pressure-compensated, load-responsive
    • 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
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
    • F15B11/042—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the feed line, i.e. "meter in"
    • 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
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
    • F15B11/044—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the return line, i.e. "meter out"
    • 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
    • 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
    • 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
    • F15B2211/25—Pressure control functions
    • 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
    • F15B2211/30505—Non-return valves, i.e. check valves
    • 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
    • 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
    • F15B2211/3055—In combination with a pressure compensating valve the pressure compensating valve is arranged between directional control valve and return line
    • 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
    • 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
    • F15B2211/35—Directional control combined with flow control
    • F15B2211/351—Flow control by regulating means in feed line, i.e. meter-in control
    • 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
    • F15B2211/35—Directional control combined with flow control
    • F15B2211/353—Flow control by regulating means in return line, i.e. meter-out control
    • 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
    • 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
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40507—Flow control characterised by the type of flow control means or valve with constant throttles or orifices
    • 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
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40515—Flow control characterised by the type of flow control means or valve with variable throttles or orifices
    • 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
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40553—Flow control characterised by the type of flow control means or valve with pressure compensating valves
    • 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
    • F15B2211/40—Flow control
    • F15B2211/415—Flow control characterised by the connections of the flow control means in the circuit
    • F15B2211/41554—Flow control characterised by the connections of the flow control means in the circuit being connected to a return line and a directional control valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/45—Control of bleed-off flow, e.g. control of bypass flow to the return line
    • 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
    • F15B2211/40—Flow control
    • F15B2211/455—Control of flow in the feed line, i.e. meter-in control
    • 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
    • F15B2211/40—Flow control
    • F15B2211/46—Control of flow in the return line, i.e. meter-out control
    • 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
    • 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
    • F15B2211/5153—Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member and a directional control valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/55—Pressure control for limiting a pressure up to a maximum pressure, e.g. by using a pressure relief valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7053—Double-acting output members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7058—Rotary output members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders

Abstract

The present invention provides a hydraulic controller in which a pressurized oil delivered from a hydraulic pump 1 is supplied to plural actuators 5,6 connected to the hydraulic pump through plural directional control valves 3,4 connected in parallel to the hydraulic pump, characterized in that each directional control valve comprises a first variable opening unit A3 and a second variable opening unit B3 provided in series in a supply line l0 extended from the hydraulic pump to the actuator, a third variable opening unit C3 provided in a return line extended from the actuator to an oil tank and a fourth variable opening unit E3 and a fifth variable opening unit D3 provided in parallel at the down stream of the third variable opening unit, wherein the fifth variable opening unit is controlled in the opening direction by an elastic force l4 and an oil pressure present between the first variable opening unit A3 and the second variable opening unit B3 and is also controlled in the closing direction by the highest of the oil pressures applied between the first variable opening unit and the second variable opening unit of each directional control valve.

Description

2359592 HYDRAULIC CONTROLLER 1 The present invention relates to a
hydraulic driving unit to be used for construction equipments, and more particularly to a hydraulic controller capable of smoothly and efficiently operating or driving plural actuators simultaneously, wherein the plural actuators are different in load from each other and are connected to a common hydraulic pump.
In Japanese patent application No. 4-107878, it is disclosed that a hydraulic controller to be used for construction equipments such as hydraulic excavators is improved in working efficiency and energy conservation property, whereby the hydraulic controller is designed to prevent a rapid drop of speed of one or more lower-load actuators in the plural actuators different in load durinp- simultaneous oneration tn the nlural netuators.
FIG. 1 is a diagram illustrative of a hydraulic circuit of this conventional hydraulic controller. The conventional hydraulic controller is provided for controlling plural actuators, for example, first and second actuators 6 and 5 which are different in load from each other. The conventional hydraulic controller has the following structure. A variable displacement pump 50 with a regulator 50a is provided for supplying pressunized oils through the Page 1 following units to the first and second actuators 6 and 5, so that the first and second actuators 6 and 5 are driven by the pressurized oils. The variable displacement pump 50 is connected through a single pump line 60 to first and second supply lines 61 and 62. The first actuator 6 is connected with a first pair of actuator lines 64a and 64b. The second actuator 5 is connected with a second pair of actuator lines 66a and 66b. A first directional control valve 51 is provided between the first pair of the actuator lines 64a and 64b and the first supply line 61. A second directional control valve 52 is provided between the second pair of the actuator lines 66a and 66b and the second supply line 62. Namely, the first actuator 6 is connected through the first pair of the actuator lines 64a and 64b, the first directional control valve 51, the first supply line 61 and the single pump line 60 to the variable displacement pump 50, so that the pressurized oil is fed ftom the variable displacement pump 50 through the single pump line 60, the first supply line 61, the first directional control valve 51, and the first pair of the actuator lines 64a and 64b to the first actuator 6 for driving the first actuator 6. The second actuator 5 is connected through the second nnir of the nctuator fines 66a and 66h- the second directional control valve 52, the second supply line 62 and the single pump line 60 to the variable displacement pump 50, so that the pressurized oil is fed from the variable displacement pump 50 through the single pump line 60, the second supply line 62, the second directional control valve 52, and the second pair of the actuator lines 66a and 66b to the second actuator 5 for driving the second actuator 5. A first oil tank 53a is provided which is connected to the Page 2 M i ........
variable displacement pump 50.
Further, a first return line 68 is connected with the first directional control valve 5 1. A second oil tank 53 b is also provided which is connected with a first tank line 69. A first auxiliary valve 54 is provided between the first return line 68 and the first tank line 69. Namely, the first actuator 6 is connected through the first pair of the actuator lines 64a and 64b, the first directional control valve 51, the first return line 68, the first auxiliary valve 54 and the first tank line 69 to the second oil tank 53b, so that the return oil is discharged from the first actuator 6 and fed through the first pair of the actuator lines 64a and 64b, the first directional control valve 5 1, the first return line 68, the first auxiliary valve 54 and the first tank line 69 to the second oil tank 53b. Furthermore, a second return line 70 is connected with the second directional control valve 52. A second auxiliary valve 55 is provided between the second return line 70 and the first tank line 69. Namely, the first actuator 5 is connected through the second pair of the actuator lines 66a and 66b, the second directional control valve 52, the second return line 70. the -,ccond auxiliary valve 55 and the first tank line 69 to the second oil tank 53b, so that the return oil is discharged from the first actuator 5 and fed through the second pair of the actuator lines 66a and 66b, the second directional control valve 52, the second return line 70, the second auxiliary valve 55 and the first tank line 69 to the second oil tank 53b.
The first pair of the actuator lines 64a and 64b receives a first load pressure. The second pair of the actuator lines 64a and 64b receives a second load Page 3 pressure. A first load pressure detecting line 73 is provided which is connected to the first directional control valve 51 which is connected with the first pair of the actuator lines 64a and 64b for detecting the first load pressure as a first unit signal pressure. A second load pressure detecting line 74 is provided which is connected to the second directional control valve 52 which is connected with the second pair of the actuator lines 66a -m and 66b for detecting the second load pressure as a second unit signal pressure. A first auxiliary valve 54 is also provided, which is connected through the first load pressure detecting line 73 to the first directional control valve 51 for receiving the first load pressure detected by the first directional control valve 51. The first auxiliary valve 54 has a first spring member 56 which receives the first load pressure detected by the first directional control valve 51 for applying a pressure to the first auxiliary valve 54, thereby increasing an opening area of the first auxiliary valve 54. A maximum pressure detecting line 75 Is also provided which extends from the first auxiliary valve 54 to a pressure compensating flow control valve 80. The first and second load pressure detecting lines 73 and 74 are c-nnected throL,(yh,) shtittp Ave 59 tr, the rnax MC innum pressilrp cletecti line 75. The first auxiliary valve 54 receives a maximum signal pressure from the maximum pressure detecting line 75 for applying a pressure to the first auxiliary valve 54 thereby decreasing the opening area of the first auxiliary valve 54. The first auxiliary valve 54 is also connected between the first return line 68 and the first tank line 69 for controlling a flow between the first return line 68 and the first tank line 69 on the basis of the Page 4 -m opening area which is also controlled by a balance of both the first unit signal pressure from the first load pressure detecting line 73 and the maximum signal pressure from the maximum pressure detecting line 75. A second auxiliary valve 55 is also provided, which is connected through the second load pressure detecting line 74 to the second directional control valve 52 for receiving the second load pressure detected by the second directional control valve 52. The second auxiliary valve 55 has a second spring member 57 which receives the second load pressure detected by the second directional control valve 52 for applying a pressure to the second auxiliary valve 55, thereby increasing an opening area of the second auxiliary valve 54. The second auxiliary valve 55 also receives the maximum signal pressure from the maximum pressure detecting line 75 for applying a pressure to the second auxiliary valve 55 thereby decreasing the opening area of the second auxiliary valve 55. The second auxiliary valve 55 is also connected between the second return line 70 and the first tank line 69 for controlling a flow between the second return line 70 and the first tank line 69 on the basis of the opening area which is controlled by a,nlpnr-P n-r 1..,nth the econd iin't sip..nal pressure from the second load pressure detecting line 74 and the maximum signal pressure from the maximum pressure detecting line 75. Namely, the maximum pressure detecting line 75 has the maximum signal pressure in all of the detected first and second unit signal pressures by the first and second load pressure detecting lines 73 and 74. A by-pass line 78 is provided between the single pump line 60 and a second tank line 77. The pressure compensating flow Page 5 control valve 80 and a control signal generator means 81 are provided on the by-pass line 78, wherein the pressure compensating flow control valve 80 is positioned in an upstream side of the control signal generator means 81, and namely the control signal generator means 81 is positioned in a upstream side of the pressure compensating flow control valve 80. A first signal pressure line 82 is provided which extends from the upstream side of the control signal generator rneans 81 to the regulator 50a of the variable displacement pump 50 for applying the pressure of the upstream side of the control signal generator means 81 to the regulator 50a of the variable displacement pump 50. The pressure compensating flow control valve 80 has a third spring member 83 which receives the maximum signal pressure from the maximum pressure detecting line 75 for applying a pressure to the pressure compensating flow control valve 80, thereby decreasing an opening area of the pressure compensating flow control valve 80. A second signal pressure line 85 is also provided which extends from the by-pass line 78 in the upstream side of the pressure compensating flow control valve 80 to the pressure compensating flow control valve 80 so that the pressure (-nmnei,snti-np flow co-.ntrn] 90 receives a pressure of the by- Pass line 78 in the upstream side of the pressure compensating flow control valve 80, whereby the opening area of the pressure compensating flow control valve 80 is increased. Further, a variable restrictor 58 is also provided on the first supply line 61 extending between the first directional control valve 51 and the single pump line 60 which is connected to the variable displacement pump 50, wherein the variable restrictor 58 is also connected to the first Page 6 -------------- return line 68 extending from the first directional control valve 51 to the first auxiliary valve 54 for receiving a pressure of the first return line 68, whereby the variable restrictor 58 controls the opening area on the basis of the pressure of the first return line 68 in order to control or adjust the flow of the pressurized oil through the first supply line 61.
As described above, the conventional hydraulic controller has the abovedescribed structure. In summary, the first and second directional control valves 51 and 52 are connected in parallel to the variable displacement pump 50. The second and first actuators 6 and 5 are connected to the first and second directional control valves 51 and 52. The first and second auxiliary valves 54 and 55 are provided respectively between the first directional control valve 51 and the tank 53 and between the second directional control valve 52 and the tank 53. The first auxiliary valve 54 receives the first load pressure detected by the first directional control valve 51 for increasing the opening area as well as receives the maximum pressure in all of the detected first and second load pressures detected by the first and second directional control valves 51 and 52 for decreasing the nnpning -rirog of the first aiixilian, valve 4. The second auxiliary valve 55 receives the second load pressure detected by the second directional control valve 52 for increasing the opening area as well as receives the maximum pressure in all of the detected first and second load pressures detected by the first and second directional control valves 51 and 52 for decreasing the opening area of the second auxiliary valve 55.
The second signal pressure line 85 is also provided which extends ftom the i 1 1 Page 7 by-pass line 78 in the upstream side of the pressure compensating flow control valve 80 to the pressure compensating flow control valve 80 so that the pressure compensating flow control valve 80 receives a pressure of the by-pass line 78 in the upstream side of the pressure compensating flow control valve 80, whereby the opening area of the pressure compensating flow control valve 80 is increased.
The above described hydraulic controller is designed to operate both the first and second actuators 6 and 5 simultaneously, provided that the second actuator 5 is much higher in load than the first actuator 6. The second signal pressure and the maximum pressure as applied to the second auxiliary valve 55 in the opposite directions are equal to each other, whereby the second auxiliary valve 55 is placed in full-opening state by a spring force given by the second spring member 57. Namely, the second load pressure of the second load pressure detecting line 74 is equal to the maximum pressure of the maximum pressure detecting line 75. By contrast, the first auxiliary valve 54 receives at its opposite sides the maximum pressure of the maximum pressure detecting line 75 and the first load pi-essil-P f the first load n,es-,tii.e detecting line 73, wherein the first load pressure of the first load pressure detecting line 73 is lower than the maximum pressure of the maximum pressure detecting line 75, whereby the first auxiliary valve 54 is placed in almost closed state by the difference in pressure between the first load pressure and the maximum pressure.
The above conventional hydraulic controller has the following disadvantages. The above conventional hydraulic controller is inapplicable Page 8 i Ch.
to the hydraulic excavator for the following reasons. If the first actuator 6 in the lower load side is used for a boom-up operation and the second actuator 5 in the higher load side is used for swing operation, then it is important for increasing a mechanical working efficiency that the boom is risen up to a predetermined height or level during an acceleration process for accelerating the swing motion with a large inertia to a predetermined swing speed from zero, so as to keep the balance between the rotational angle and the height of the risen boom. Notwithstanding, as described above, the first auxiliary valve 54 is placed in almost closed state by the difference in pressure between the first load pressure and the maximum pressure, then the operation of the boom-up operation driven by the first actuator 6 in the low load side is delayed as compared to the swing operations driven by the second actuator 5 in the high load side. This delay makes it difficult to improve the mechanical working efficiency.
In the above circumstances, it had been required to develop a novel hydraulic controller free from the above problem.
Accordingly, it is an object of the present invention to provide a novel h-,,draulic controller free frnm the above problems.
It is a further object of the present invention to provide a novel hydraulic 20 controller allowing a common pump to simultaneously drive plural actuators different in load from each other without placing the actuator in the lower load side into an insufficient operational speed.
It is a still further object of the present invention to provide a novel hydraulic controller allowing a common pump to simultaneously drive Page 9 plural actuators different in load from each other without appearance of cavitation. It is yet a further object of the present invention to provide a novel hydraulic controller allowing a common pump to simultaneously drive plural actuators different in load from each other without placing the actuator in the higher load side into a disfunctional state.
-m 1 1 1 The present invention provides a hydraulic controller in which a pressurized oil delivered from a hydraulic pump is supplied to plural actuators connected to the hydraulic pump through plural directional control valves connected in parallel to said hydraulic pump and each directional control valve comprises a first variable opening unit and a second variable opening unit provided in series in a supply line extended ftom the hydraulic pump to the actuator, a third variable opening unit provided in a return line extended from the actuator to an oil tank and a fourth variable opening unit and a fifth variable opening unit provided in parallel at the down stream of the third variable opening unit, wherein the fifth variable opening unit is controlled in the opening direction by an elastic force and an oil pressure applied bet,,keen the first varinble opening unit and the second variable opening unit and is also controlled in the closing direction by a maximum oil pressure selected at higher level from the oil pressures applied between the first variable opening unit and the second variable opening unit of each directional control valve.
The above and other objects, features and advantages of the present invention will be apparent from the following descriptions.
Page 10 -m Preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a diagram illustrative of a hydraulic circuit of the conventional hydraulic controller.
FIG. 2 is a diagram illustrative of a hydraulic circuit of a first novel hydraulic controller in a first embodiment in accordance with the present invention.
FIG. 3 is a fragmentary diagram illustrative of a double-action type control valve structure of a first directional control valve connected to a first actuator in FIG. 2.
FIG. 4 is a diagram illustrative of a hydraulic circuit of a second novel hydraulic controller in a second embodiment in accordance with the present invention.
FIG. 5 is a diagram illustrative of a hydraulic circuit of a third novel 15 hydraulic controller in a third embodiment in accordance with the present invention.
FIG. 6 is a diagram illustrative of a hydraulic circuit of a fourth novel hydraulic controller in a fourth embodiment in accordance with the present invention.
It is preferable that the first, third and fourth variable opening units provide opening areas by the control signal of the directional control valve, while an opening area of the second variable opening unit is adjusted by an external signal in accordance with a load of the actuator.
It is also preferable that the hydraulic pump is a variable displacement Page 11 pump which is controlled in the delivery flow rate in accordance with the control signal of the directional control valve.
it is also preferable that a by-pass line extends from an intermediate point between a pump line of the hydraulic pump and the directional control valve to the oil tank and in the by-pass line is provided a switch valve an opening area of which is adjusted by the control signal of the directional control valve and a flow rate detecting means is provided at the down stream of the switch valve, whereby a delivery rate of the variable displacement pump is controlled in accordance with the flow rate detected by the flow rate detecting means.
It is also preferable that a by-pass line extending from an intermediate point on the pump line to the tank, a pressure control valve provided on the bypass line which is controlled in the opening direction by a oil pressure of the pump line and also in the closing direction by an selected maximum oil pressure and the elastic force, a pressure generating means provided at the down stream of the pressure control valve, whereby the delivery rate of the variable displacement pump is controlled in accordance with the oil pressure of the upstream side of the pressure generating means.
It is also preferable that at least one of the plural actuators comprises an oil 20 cylinder, a directional control valve connected to the oil cylinder and a check valve provided on a line extending from the first intermediate point between the third and fifth variable opening units to second intermediate point between the first and second variable opening units and the cheek valve pen-nits an oil flow ftom the first intermediate point to the second Page 12 u j intermediate point.
It is also preferable that the directional control valve comprises a closedcenter type control valve.
The present invention will be described in detail with reference to the 5 drawings. FIG. 2 is a diagram illustrative of a hydraulic circuit of a first novel hydraulic controller in a first embodiment in accordance with the present invention.
The first novel hydraulic controller is provided for controlling plural actuators, for example, first and second actuators 5 and 6 which are different in load from each other, wherein the first actuator 5 is a high load side actuator, whilst the second actuator 6 is a low load side actuator. The first novel hydraulic controller has the following structure. A hydraulic pump 1 is provided which has a regulator 2 for allowing the hydraulic pump 1 to serve as a variable displacement pump. First and second directional control valves 3 and 4 are provided which are connected in parallel to each other through a pump line 7 to the hydraulic pump 1. The first actuator 5 is connected to the first directional control valve 3, whilst the second actuator 6 i-, connected to the second directional control valve 4. The first actuator 5 is much higher in load than the second actuator 6. The first and second directional control valves 3 and 4 have the following structures.
The first directional control valve 3 further has a first variable opening unit A3, a second variable opening unit B3, a third variable opening unit C3, a fourth variable opening unit D3 and a fifth variable opening unit E3 as well Page 13 as has a first port 29- 1, a second port 30- 1, a third port 3 1 -1 and a fourth port 32-1. A first supply line 17a to the first actuator 5 is provided which extends from the first port 29-1 of the first directional control valve 3 to a supply side of the first actuator 5. A first return line 17b is provided which extends from a return line of the first actuator 5 to the second port 30- 1 of the first directional control valve 3. The third port 31-1 of the first directional control valve 3 is connected through the pump line 7 to the hydraulic pump 1. The first directional control valve 3 has a first supply line 10 which extends from the third port 3 1 -1 to the first port 29- 1. The first and second variable opening units A3 and B3 are provided on the first supply line 10, wherein the first variable opening unit A3 is positioned in an upstream side of the second variable opening unit B3, whilst the second variable opening unit B3 is positioned in a downstream side of the first variable opening unit A3. The first directional control valve 3 also has a first return line 19 which extends from the second port 30-1 to the fourth port 32-1. The third and fifth variable opening units C3 and E3 are provided on the first return line 19, wherein the third variable opening unit C3 is nosifinned in an unstrearn side of the fifth variable opening unit E3. whilst the fifth variable opening unit E3 is positioned in a downstream side of the third variable opening unit C3. A first by-pass line 20 is provided which extends across the fifth variable opening unit E3, so that the first bypass line 20 provides a bypass between the third variable opening unit C3 and the fourth port 32-1. The fourth variable opening unit D3 is provided on the first by-pass line 20. The fourth port 32-1 of the first directional Page 14 control valve 3 is connected to a first tank 16a. The fifth variable opening unit E3 of the first directional control valve 3 has a first side which has a first spring member 14 for applying a force to the fifth variable opening unit E3 to place the fifth variable opening unit E3 into an opening state. A first signal pressure line 12 is also provided which is connected to the first side of the fifth variable opening unit E3. The first signal pressure line 12 is also connected to the first supply line 10, so that the first signal pressure line 12 is always identical in oil pressure with the first supply line 10. A first maximum pressure line 9-1 is also provided which is connected to a second side of the fifth variable opening unit E3. Applying of the first signal pressure line 12 to the fifth variable opening unit E3 increases an opening area of the fifth variable opening unit E3 for placing the fifth variable opening unit E3 into an opening state. Applying of the maximum pressure of the first maximum pressure line 9-1 to the fifth variable opening unit E3 decreases an opening area of the fifth variable opening unit E3 for placing the fifth variable opening unit E3 into a closing state.
The second directional control valve 4 further has a first variable opening lin;t A4. 2 -e.cnnd variable oneninR unit B4. a third variable opening unit C4, a fourth variable opening unit D4 and a fifth variable opening unit E4 as well as has a first port 29-2, a second port 30-2, a third port 31-2 and a fourth port 32-2. A second supply line 18a is provided which extends ftom the first port 29-2 of the second directional control valve 4 to a supply side of the second actuator 6. A second actuator return line 18b is provided which extends from a return side of the second actuator 6 to the second port Page 15 30-2 of the second directional control valve 4. The third port 31-2 of the second directional control valve 4 is connected through the pump line 7 to the hydraulic pump 1. The second directional control valve 4 has a second supply line 11 which extends from the third port 31-2 to the first port 29-2. The first and second variable opening units A4 and B4 are provided on the second supply line 11, wherein the first variable opening unit A4 is positioned in an upstream side of the second variable opening unit B4, whilst the second variable opening unit B4 is positioned in a downstream side of the first variable opening unit A4. The second directional control valve 4 also has a second return line 21 which extends from the second port 30-2 to the fourth port 32-2. The third and fifth variable opening units C4 and E4 are provided on the second return line 2 1, wherein the third variable opening unit C4 is positioned in an upstream side of the fifth variable opening unit E4, whilst the fifth variable opening unit E4 is positioned in a downstream side of the third variable opening unit C4. A second by-pass line 22 is provided which extends across the fifth variable opening unit E4, so that the second by-pass line 22 provides a by-pass between the third variable opening unit C4 and the fourth port 32-2. The fourth variable opening unit D4 is provided on the second by-pass line 22. The fourth port 32-2 of the second directional control valve 4 is connected to a second tank 16b. The fifth variable opening unit E4 of the second directional control valve 4 has a first side which has a second spring member 15 or a first spring member 14 for applying a force to the fifth variable opening unit E4 to place the fifth variable opening unit E4 into an opening state. A second Page 16 M 1 signal pressure line 13 is also provided which is connected to the first side of the fifth variable opening unit E4. The second signal pressure line 13 is also connected to the second supply line 11, so that the second signal pressure line 13 is always identical in oil pressure with the second supply line 11. A second maximum pressure line 9-2 is also provided which is connected to a second side of the fifth variable opening unit E4. Applying of the second signal pressure of the second signal pressure line 13 to the fifth variable opening unit E4 increases an opening area of the fifth variable opening unit E4 for placing the fifth variable opening unit E4 into an opening state. Applying of the maximum pressure of the second maximum pressure line 9-2 to the fifth variable opening unit E4 decreases an opening area of the fifth variable opening unit E4 for placing the fifth variable opening unit E4 into a closing state.
The above first and second directional control valves are closed center directional control valves. The pressurized oil is fed from the hydraulic pump 1 to the first actuator 5 through the pump line 7, the first supply line 10 and the first supply line 17a. The pressurized oil is thenreturned from the first actuator 5 to the first tank 16a through the first actuator return line 17b, and the first return line 19. The pressurized oil is also fed fi-om the hydraulic pump 1 to the second actuator 6 through the pump line 7, the second supply line 11 and the second supply line 18a. The pressurized oil is then returned from the second actuator 6 to the second tank 16b through the second actuator return line 18b, and the second return line21. Namely, the pressurized oil is fed from the hydraulic pump 1 through the first and Page 17 second variable opening units A3 and B3 of the first directional control valve 3 to the first actuator 5 and then the pressurized oil is returned from the first actuator 5 through the third variable opening unit C3 and one or either of the fourth and fifth variable opening units D3 and E3 of the first directional control valve 3 to the first tank 16a. The pressurized oil is also fed from the hydraulic pump 1 through the first and second variable opening units A4 and B4 of the second directional control valve 4 to the second actuator 6 and then the pressurized oil is returned from the second actuator 6 through the third variable opening unit C4 and one or either of the fourth and fifth variable opening units D4 and E4 of the second directional control valve 4 to the second tank 16b. Each of the first to fifth variable opening units A3, B3, C3, D3 and E3 of the first directional control valve 3 as well as each of the first to fifth variable opening units A4, B4, C4, D4 and E4 of the second directional control valve 4 may comprise a variable throttle or a variable restrictor or a valve controllable in flow rate.
Although in FIG. 2, the first and second directional control valves 3 and 4 are illustrated with a one way arrow mark, it is possible to drive the first and second directional control valves 3 and 4 in both directions by simultaneously switching the first to fourth ports 29-1, 3 0-1, 3 1 -1 and 32-1 of the first directional control valve 3 or simultaneously switching the first to fourth ports 29-2, 30-2, 31-2 and 32-2 of the second directional control valve 4. The hydraulic pump 1 has a regulator 2 which is connected to a displacement control signal pressure line 27, so that the regulator 2 receives a pump displacement control signal pressure line to control the pump Page 18 i i ' ' --- displacement of the hydraulic pump 1 on the basis of operation amount of the first and second directional control valves 3 and 4.
Further, first and second pressure control valves 33 and 34 are provided which serve as safety valves. The first pressure control valve 33 is connected to the second actuator return line 18b connected to the return side of the second actuator 6 for preventing any excessively high oil pressure from being applied to a rod side 36 of the second actuator 6. The first pressure control valve 33 is also connected to a third thank 16c. The second pressure control valve 34 is connected to the second supply line 18a connected to the supply side of the second actuator 6 for preventing any excessively high oil pressure from being applied to a head side 35 of the second actuator 6. The second pressure control valve 34 is also connected to the third thank 16c.
Furthermore, a higher pressure selector 25 is provided which connects between the first signal pressure line 12 connected to the fifth variable opening unit E3 of the first directional control valve 3 and the second signal pressure line 13 connected to the fifth variable opening unit E4 of the second directional control valve 4 for selecting higher one of the first oil pressure of the first signal pressure line 12 ane ine second oil pressure of the second signal pressure line 13, so that the selected higher one of the first oil pressure of the first signal pressure line 12 and the second oil pressure of the second signal pressure line 13 is supplied to the first and second maximum pressure lines 9-1 and 9-2, whereby the oil pressure of the first and second maximum pressure lines 9-1 and 9-2 is substantially Page 19 equal to the selected higher one of the first oil pressure of the first signal pressure line 12 and the second oil pressure of the second signal pressure line 13.
The first and second variable opening units A3 and 133 are provided in series to each other between the hydraulic pump 1 and the supply side of the first actuator 17a. The fourth and fifth variable opening units D3 and E3 are provided in parallel to each other through the third variable opening unit C3 to the return side of the first actuator 17b. The first directional control valve 3 illustrated in FIG. 2 is one state into which the double- action directional control valve of FIG. 3 is switched.
Operation of the above novel hydraulic controller will subsequently be described. The following descriptions will be made in such a case that the load to the second actuator 6 is much lower than the load to the first actuator 5. The first and second directional control valves 3 and 4 are simultaneously operated, whereby the pressurized oil discharged from the hydraulic pump 1 is likely to be flown toward the second actuator 6 in the lower load side. As a result, a difference in pressure between the upstream and downstream sides of the first variable opening unit A4 of the second directional control valve 4 becomes larger than a difference in pressure between the upstream and downstream sides of the first variable opening Unit A3 of the first directional control valve 3, whereby the first supply line 10 becomes higher in oil pressure than the second supply line 11. The first signal pressure line 12 is connected with the first supply line 10 whilst the second signal pressure line 13 is connected with the second supply line 11.
Page 20 1 Therefore, the first signal pressure line 12 becomes higher in oil pressure than the second signal pressure line 13. The higher pressure selector 25 connected between the first and second signal pressure lines 12 and 13 selects the first oil pressure of the first signal pressure line 12 or the first supply line 10, whereby the maximum pressure of the first and second maximum pressure lines 9-1 and 9-2 becomes equal to the first oil pressure of the first pressurized oil supply line 10 or the first signal pressure line 12. As a result, both the first and second sides of the fifth variable opening unit E3 of the first directional control valve 3 receive the same oil pressure as the first pressurized oil supply line 10, whereby the first spring member 14 provides a spring force which places the fifth variable opening unit E3 into a full-opening state. The first side of the fifth variable opening unit E4 of the second directional control valve 4 receives the second oil pressure of the second pressurized oil supply line 11 or the second signal pressure line 13 which is lower than the above first oil pressure, whilst the second side of the fifth variable opening unit E4 of the second directional control valve 4 receives the above first oil pressure of the first supply line 10, for which reason the opening area of the second directional control valve 4 is restricted by a balance of the first oil pressure of the first pressurized oil supply line 10 and the sum of the second oil pressure of the second pressurized oil supply line 11 and the spring force by the second spring member 15 or the first spring member 14. As a result, the opening area of the fifth variable opening unit E3 of the first directional control valve 3 is full-opening state, whilst the opening area of the fifth variable opening unit Page 21 1 j ---- E4 of the second directional control valve 4 is such a partial or restrictedopening state that the first and second oil pressures of the first and second supply lines 10 and 11 become substantially equal to each other. This means that even if the second actuator 6 is lower in load than the first actuator 5, then the fifth variable opening unit E4 of the second directional control valve 4 restricts the flow rate of the return oil returned from the second actuator 6. As a result, the second oil pressure of the second pressurized oil supply line 11 is increased up to such a high pressure as capable of driving the first actuator 5, whereby the pressurized oil delivered from the hydraulic pump 1 is divided into the first and second actuators 5 and 6 at a flow rate ratio based upon a ratio of the first and second opening area of the first variable opening units A3 and A4 of the first and second directional control valves 3 and 4.
The above first novel hydraulic controller is applicable to the hydraulic excavator for the following reasons. If the first actuator 5 is used for a swing operation and the second actuator 6 is used for boom-up operation, then it is important for increasing a mechanical working efficiency that the booil.);,z iin to a predetermined beight or level during an acceleration process for accelerating the swing motion with a large inertia to a predetermined swing speed from zero, so as to keep the balance between the rotational angle and the height of the risen boom. As described and illustrated in this first embodiment, the fourth and fifth variable operuing units D4 and E4 are provided in parallel to each other, so that if the opening area of the fifth variable opening unit E4 is extremely small, then the return Page 22 oil returned from the second actuator 6 is flown through the third and fourth variable opening units C4 and D4 of the second directional control valve 4. Namely, the second by-pass 22 having the fourth variable opening unit D4 is provided in the return line, so that both swing operation of rotating and boom-up operation of the hydraulic excavator are effective. This results in a remarkable improvement in workability of the machine using the above novel hydraulic controller.
Subsequently, the following descriptions will be made in such a case that the second actuator 6 is a cylinder type actuator and the pressurized oil delivered from the hydraulic pump 1 is fed to the head side 35 of the second actuator 6, so that the second actuator 6 in the lower load side is driven simultaneously with the first actuator 5.
As described above and illustrated in FIG. 2, the first and second pressure control valves 33 and 34 are provided which are connected to the rod side 36 and the head side 35 of the second actuator 6 respectively, for the purpose of preventing any excessively high oil pressure from being applied to the second actuator 6.
In the above first novel hydraulic controller, the second directional control valve 4 has the second variable opening unit B4 for the purpose of making the above first novel hydraulic controller free from the following problems. If.the first actuator 5 in the high load side has an extremely high load, the' oil pressure of the pump line 7 is increased, and a difference in pressureapplying area between the head side 35 and the rod side 36 of the second actuator 6 causes a pressure of the rod side 36 of the second actuator 6 to Page 23 be so increased as to open the first pressure control valve 33, resulting in that the pressure of the rod side 36 of the second actuator 6 does not reach the sufficiently high pressure for driving the first actuator 5. In accordance with the present invention, however, the second variable opening unit B4 is provided on the second supply line 11 in the second directional control valve 4, wherein the opening area of the second variable opening unit B4 is so restricted or controlled as to generate a difference in oil pressure between the upstream and downstream sides of the second variable opening unit B4, whereby the oil pressure of the second supply line 18a extending between the second variable opening unit B4 of the second directional control valve 4 and the head side 35 of the second actuator 6 does not reach a sufficiently high oil pressure for opening the first pressure control valve 33 connected to the rod side 36 of the second actuator 6. As a result, the oil pressure of the pump line 7 is so increased as to drive the first actuator 5 having the high load.
It is possible that the second variable opening unit B3 of the first directional control valve 3 comprises a check valve which opening area is controlled by an external signal for preventing the pressurized oil from any reverse flow from the first actuator 5 to the pump line 7, and also the second variable opening unit B4 of the second directional control valve 4 comprises a check valve which opening area is controlled by an external signal for preventing the pressurized oil from any reverse flow from the second actuator 6 to the pump line 7.
The first directional control valve 3 may comprise a first notch and a first Page 24 body accommodating a first spool, wherein the first, third and fourth variable opening units A3, C3 and D3 are formed on the first spool. The second directional control valve 4 may also comprise a second notch and a second body accommodating a second spool, wherein the first, third and fourth variable opening units A4, C4 and D4 are formed on the second spool. The first, third and fourth variable opening units A3, C3 and D3 of the first directional control valve 3 as well as the first, third and fourth variable opening units A4, C4 and D4 of the second directional control valve 4 are controlled in opening area in accordance with control signals "S", which are control signals of the first and second directional control valves 3 and 4. The second variable opening unit B3 of the first directional control valve 3 and the second variable opening unit B4 of the second directional control valve 4 are controlled in opening area in accordance with the external signal "Sl" in consideration of the balance in load between the simultaneously operated first and second actuators 5 and 6. It is also possible that the displacement of the variable displacement hydraulic pump. 1 is controlled by a control signal proportional to or according to the signal for operating the directional control valve spool.
As described above, the above first novel hydraulic controller in 20 accordance with the first embodiment in accordance with the present invention provides the following advantages.
The hydraulic circuit is provided between the hydraulic pump and the plural actuators different in load from each other. The hydraulic circuit has plural directional control valves in correspondence with the plural actuators, Page 25 wherein the plural directional control valves are parallel to each other and are connected to the corresponding plural actuators. Each of the plural directional control valves has first and second variable opening units provided in series on an oil supply Ime extending from the hydraulic pump to the corresponding actuator and further has a third variable opening unit provided on an oil return line extending from the corresponding actuator to a corresponding tank as well as fourth and fifth variable opening units provided in parallel to each other and on the oil return line in a downstream side of the third variable opening unit. The fifth variable opening unit has a first side connected to an intermediate point of the oil supply line positioned between the first and second variable opening units so that the first side of the fifth variable opening unit receives a signal oil pressure of the downstream side of the first variable opening unit and of the upstream side of the second variable opening unit. The fifth variable opening unit has a second side connected to a maximum oil pressure line extending commonly over the directional control valve, so that the second side of the fifth variable opening unit receives a maximum oil pressure of the maxi.mL.,m oil pressure line. A maximur- oil pressure selector is also provided commonly to all of the plural directional control valves, wherein the maximum oil pressure selector is connected to the intermediate point between the first and second variable opening units of each of the plural directional control valves for selecting highest one of the individual signal oil pressures of the plural directional control valves and making a maximum oil pressure of the maximum oil pressure line substantially equal Page 26 to the highest one of the individual signal oil pressures. The first side of the fifth variable opening unit also has an elastic force-applying device, for example, a spring member, so that a sum of an elastic force of the elastic force-applying device and the individual signal oil pressure applied to the first side of the fifth variable opening unit provides an opening force which increases an opening area of the fifth variable opening unit, whilst the C maximum oil pressure applied to the second side of the fifth variable opening unit provides a closing force which decreases the opening area of the fifth variable opening unit. This structure makes it possible that an oil pressure of a pump line extending between the hydraulic pump and each of the plural directional control valves is increased up to a sufficiently high oil pressure for driving highest load driving one of the plural actuators. Therefore, the above first novel hydraulic controller is capable of simultaneously operating or driving the plural actuators different in load, independently from characteristics or performances of the base machine to which the above first novel hydraulic controller is applied. The above first novel hydraulic controller is free from the problems with insufficient speed of the lower load driving actuator of the plural actuators when the plural actuators are simultaneously operated or driven and further with nonoperability of the higher load driving actuator.
Another embodiment according to the present invention will be described in detail with reference to the drawings. FIG. 4 is a diagram illustrative of a hydraulic circuit of a second novel hydraulic controller in a second embodiment in accordance with the present invention.
Page 27 Further, a check valve 39 is provided on an line extending between an intermediate point 38 on the second supply line 11 between the first and second variable opening units A4 and B4 of the second directional control valve 4 and another intermediate point 37 on the second return line 21 between the third and fifth variable opening units C4 and E4 of the second directional control valve 4, wherein the other intermediate point 37 is also one end of the second by-pass 22. The check valve 39 permits a one way flow from the other intermediate point 37 to the interTnediate point 38.
Operation of the above novel hydraulic controller will subsequently be 10 described. The following descriptions will be made in such a case that the first and second actuators 5 and 6 are simultaneously operated or driven, wherein the load to the second actuator 6 is subjected to a free- fall, whilst the load to the first actuator 5 is subjected to a swing motion. In this case, the oil pressure for driving the first actuator 5 is higher than the oil pressure for driving the second actuator 6. As a result, a difference in pressure between the upstream and downstream sides of the first variable opening unit A4 of the second directional control valve 4 becomes larger than a ul'.fference in pressure -,,-.st.-eam and downstream sides ef tl- first variable opening unit A3 of the first directional control valve 3, whereby the first supply line 10 becomes higher in oil pressure than the second supply line 11. The first signal pressure li-ne 12 is connected with the first supply line 10, whilst the second signal pressure line 13 is connected with the second supply line 11. Therefore, the first signal pressure line 12 becomes higher in oil pressure than the second signal Page 28 - - 1 - pressure line 13. The higher pressure selector 25 connected between the first and second signal pressure lines 12 and 13 selects the first oil pressure of the first signal pressure line 12 or the first supply line 10, whereby the maximum pressure of the first and second maximum pressure lines 9-1 and 9-2 becomes substantially equal to the first oil pressure of the first supply line 10 or the first signal pressure line 12. As a result, both the first and second sides of the fifth variable opening unit E3 of the first directional control valve 3 receive the same oil pressure as the first supply line 10, whereby the first spring member 14 provides a spring force which places the fifth variable opening unit E3 into a full-opening state. The first side of the fifth variable opening unit E4 of the second directional control valve 4 receives the second oil pressure of the supply line 11 or the second signal pressure line 13 which is lower than the above first oil pressure, whilst the second side of the fifth variable opening unit E4 of the second directional control valve 4 receives an application of the above first oil pressure of the first supply line 10, for which reason the opening area of the fifth variable opening unit E4 of the second directional control valve 4 is restricted by a ef the f,r-,t c;l ----ssjre of the first supply line 10 and the surn of the second oil pressure of the second supply line 11 and the spring force by the second spring member 15. As a result, the opening area of the fifth variable opening unit E3 of the first directional control valve 3 is full-opening state, whilst the opening area of the fifth variable opening unit E4 of the second directional control valve 4 is a partial or restricted-opening state. As a result, the oil pressure at the intermediate point 37 is increased, whilst the Page 29 oil pressure at the intermediate point 38 is lower than the oil pressure of the intennediate point 37 because the load to the second actuator 6 is subjected to the free-fall. The return pressurized oil at the intermediate point 37 flows through the check valve 39 to the intermediate point 38. Namely, a part of the pressurized oil returned from the second actuator 6 and fed toward the -m second tank 16b, is recycled through the supply line 11 to the second actuator 6. This causes that the majority part of the pressurized oil delivered from the hydraulic pump 1 is fed through the first directional control valve 3 to the first actuator 5, thereby allowing a high speed driving of the first and second actuators 5 and 6 different in load from each other. As a result, the performance of the hydraulic machine using the above novel hydraulic controller is largely improved.
The above second novel hydraulic controller is applicable to the hydraulic excavator for the following reasons. If the first actuator 5 is used for a swing operation and the second actuator 6 is used for boom-up operation, then it is important for increasing a mechanical working efficiency that the boom is risen up to a predetermined height or level during an acceleration process for accelerating the swing motion with a large inertia to a predetermined swing speed from zero, so as to keep the balance between the rotational angle and the height of the risen boom. As described and illustrated in this second embodiment, the fourth and fifth variable opening units D4 and E4 are provided in parallel to each other, so that if the opening area of the fifth variable opening unit E4 is extremely small, then the pressurized oil returned from the second actuator 6 is flown through the Page 30 third and fourth variable opening units C4 and D4 of the second directional control valve 4. Namely, the second by-pass 22 having the fourth variable opening unit D4 is provided in the return line, so that both swing operation and boom-up operation of the hydraulic excavator are effective. This results in a remarkable improvement in workability of the machine using the above novel hydraulic controller.
As described above, the above second novel hydraulic controller in accordance with the second embodiment in accordance with the present invention provides the same advantages of Example 1.
Further, the directional control valve connected to the lower load driving actuator comprises the one way flow permitting device, for example, the check valve provided between the intermediate point on the supply line between the first and second variable opening units and the other intermediate point on the return line between the third and fifth variable opening units for permitting the one way flow from the oil return line to the oil supply line, so that a part of a pressurized oil returned from the lower load driving actuator is recycled through the oil supply line to the lower load drivinQ actuator. whereby a malority part of the pressurized oil delivered fl.om the hydraulic pump is fed through the other directional control valve to the higher load driving actuator, resulting in that the increased hiQh speed driving operation of the plural actuators are realized.
The workability of the base machine, to which the above second novel hydraulic controller is applied, is remarkably improved.
The substantial sequences of the pump delivery control by the hydraulic Page 3 1 controller according to the invention will be described with reference to Figures 5 and 6. The control sequences as hereinafter described may be applicable to either the hydraulic controller of the first embodiment or that of the second embodiment, notwithstanding for convenience in better understanding sequences of Figs. 5 and 6 are described in association with the hydraulic controller of the first embodiment.
According to the arrangement of Fig.5, when neither actuator 12 nor actuator 14 is operated, the control signal S is not input into the switch valve 41 so that the switch valve 41 is maintained in a full open state and thus the by-pass flow rate to be detected at the flow rate detecting means 42 amounts a full discharge flow rate of the pump 44. Namely, a solenoid valve 43 is fully opened and the full discharge flow rate of the pump 44 is passed through the solenoid valve 43 and the line 37 into the regulator 2 to advance the piston of the regulator 2 to the right direction as shown in Fig.
5 for decreasing the discharge flow rate of the pump 1.
Accordingly, when none of the actuator is operated, the discharge flow rate of the pump 1 reaches at minimum. While, when either one or both of the first directional control valve 3 or the second directional control valve 4 is/are operated, the control signal S is input into the switch valve 41 so that the switch valve 41 is restricted to the opening area corresponding to the control signal S and the by-pass flow rate to be detected at the flow rate detecting means 42 is decreased. Thus, the opening area of the solenoid valve 43 is decreased and the piston of the regulator 2 is moved into the left direction as shown in Fig.5 for increasing the pump discharge flow rate to Page 32 obtain the discharge flow rate corresponding to the control signal S. Namely, the pump 1 delivers the fluid at the discharge flow rate in correspondence with the operation amount of the first directional control valve and the second directional control valve, which ensures the control of 5 the pump 1 with improved energy conservation and manipulation.
In accordance with the arrangement of Fig. 6, the delivery rate of the pump 1 when neither the actuator 12 nor the actuator 14 is operated reaches at the minimum flow rate and to the delivery rate matching with the load pressure when the actuator 12 or the actuator 14 actuates alone. Further, in the simultaneous operation of the actuators 12 and 14, the delivery rate matching with the maximum load pressure in the hydraulic controller is obtained to perform the pump control with improved energy saving and manipulation.
Whereas modifications of the present invention will be apparent to a person having ordinary skill in the art, to which the invention pertains, it is to be understood that embodiments as shown and described by way of illustrations are by no means intended to be considered in a limiting sense.
AccordinQ1v. it is to be intended to cover by claims all modifications which fall within the spirit and scope of the present invention.
Page 33

Claims (7)

  1. What is claimed is:
    -m 1. A hydraulic controller in which a pressurized oil delivered ftorn a hydraulic pump is supplied to plural actuators connected to the hydraulic pump through plural directional control valves connected in parallel to the hydraulic pump, characterized in that each directional control valve comprises a first variable opening unit and a second variable opening unit provided in series in a supply line extended from the hydraulic pump to the actuator, a third variable opening unit provided in a return line extended from the actuator to an oil tank and a fourth variable opening unit and a fifth variable opening unit provided in parallel at the down stream of the third variable opening unit, wherein the fifth variable opening unit is controlled in the opening direction by an elastic force and an oil pressure applied between the first variable opening unit and the second variable opening unit and is also controlled in the closing direction by a maximum oil pressure selected at higher level ftom the oil pressures applied between the first variable opening unit and the second variable opening unit of each directional control valve.
  2. 2. The hydraulic controller as claimed in claim 1, in which the first, third and fourth variable opening units provide opening areas by the control signal of the directional control valve, while an opening area of the second variable opening unit is adjusted by an external signal in accordance with a load of the actuator.
  3. 3. The hydraulic controller as claimed in claim 1 or 2, Page 34 in which the hydraulic pump is a variable displacement pump which is controlled in the delivery flow rate in accordance with the control signal of the directional control valve.
  4. 4. The hydraulic controller as claimed in claim 1, 2 or 3, in which a by5 pass line extends from an intermediate point between a pump line of the hydraulic pump and the directional control valve to the oil tank and in the by-pass line is provided a switch valve an opening area of which is adjusted by the control signal of the directional control valve and a flow rate detecting means is provided at the down stream of the switch valve, whereby a delivery rate of the variable displacement pump is controlled in accordance with the flow rate detected by the flow rate detecting means.
  5. 5. The hydraulic controller as claimed in claim 1, 2 or 3, which further comprises a by-pass line extending from an intermediate point on the pump line to the tank, a pressure control valve provided on the by-pass line which is controlled in the opening direction by a oil pressure of the pump line and also in the closing direction by an selected maximum oil pressure and the elastic force, a pressure generating means provided at the down stream of the pressure control valve. whereby the delivery rate of the variable displacement pump is controlled in accordance with the oil pressure of the upstream side of the pressure generating means.
  6. 6. The hydraulic controller as claimed in any one of claims 1-5, in which at least one of the plural actuators comprises an oil cylinder, a directional control valve connected to the oil cylinder and a check valve provided on a line extending from the first intermediate point between the third and fifth Page 3 5 variable opening units to second intermediate point between the first and second variable opening units and the check valve permits an oil flow from the first intermediate point to the second intermediate point.
  7. 7. The hydraulic controller as claimed in any one of claims 1 to 6, in which the directional control valve comprises a closed-center type control valve.
    Page 36
GB0104782A 2000-02-24 2001-02-26 Hydraulic controller Expired - Fee Related GB2359592B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2000048383 2000-02-24

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GB0104782D0 GB0104782D0 (en) 2001-04-18
GB2359592A true GB2359592A (en) 2001-08-29
GB2359592B GB2359592B (en) 2004-05-26

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GB0031850A Ceased GB0031850D0 (en) 2000-02-24 2000-12-29 Hydraulic controller
GB0104782A Expired - Fee Related GB2359592B (en) 2000-02-24 2001-02-26 Hydraulic controller

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4083337A4 (en) * 2019-12-27 2024-01-10 Kubota Kk Working machine

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4083337A4 (en) * 2019-12-27 2024-01-10 Kubota Kk Working machine

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Publication number Publication date
GB0104782D0 (en) 2001-04-18
GB0031850D0 (en) 2001-02-14
GB2359592B (en) 2004-05-26

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