Apparatus for recovering pressure oil returned from actuators

• US 6,151,894 A
• Filed: 06/25/1999
• Issued: 11/28/2000
• Est. Priority Date: 12/26/1996
• Status: Expired due to Fees

• Current Assignee: Komatsu Ltd.
• Original Assignee: Komatsu Ltd.
• Inventors: Maruta, Kazuhiro, Endo, Hiroshi, Yoshida, Nobumi
• Primary Examiner(s): LOPEZ, FRANK D
• Application Number:
  US09/331,788
• Time in Patent Office: 522 Days
• Field of Search: 60/414, 60/417
• US Class Current: 60/414
• CPC Class Codes: E02F 9/2207 for reducing or compensating oscillations
• CPC Class Codes: E02F 9/2217 with energy recovery arrangements, e.g. using accumulators, flywheels
• CPC Class Codes: E02F 9/2228 including an electronic controller
• CPC Class Codes: E02F 9/2267 Valves or distributors position of valves arrangements on upper-structures E02F9/0875
• CPC Class Codes: E02F 9/2271 Actuators and supports therefor and protection therefor
• CPC Class Codes: E02F 9/2285 Pilot-operated systems
• CPC Class Codes: E02F 9/2292 Systems with two or more pumps
• CPC Class Codes: E02F 9/2296 Systems with a variable displacement pump
• CPC Class Codes: F15B 11/02 Systems essentially incorporating special features for controlling the speed or actuating force of an output member
• CPC Class Codes: F15B 11/16 with two or more servomotors
• CPC Class Codes: F15B 21/14 Energy-recuperation means
• CPC Class Codes: F15B 2211/20553 with pilot circuit, e.g. for controlling a swash plate
• CPC Class Codes: F15B 2211/20569 capable of working as pump and motor
• CPC Class Codes: F15B 2211/20576 with multiple pumps
• CPC Class Codes: F15B 2211/212 the pressure sources being accumulators
• CPC Class Codes: F15B 2211/30515 Load holding valves
• CPC Class Codes: F15B 2211/3111 the pump port being closed in the centre position, e.g. so-called closed centre
• CPC Class Codes: F15B 2211/31541 having a single pressure source and multiple output members
• CPC Class Codes: F15B 2211/31576 having a single pressure source and a single output member
• CPC Class Codes: F15B 2211/329 actuated by fluid pressure
• CPC Class Codes: F15B 2211/351 : Flow control by regulating means in feed line, i.e. meter-in control
• CPC Class Codes: F15B 2211/353 : Flow control by regulating means in return line, i.e. meter-out control
• CPC Class Codes: F15B 2211/40515 : with variable throttles or orifices
• CPC Class Codes: F15B 2211/428 : actuated by fluid pressure
• CPC Class Codes: F15B 2211/45 : Control of bleed-off flow, e.g. control of bypass flow to the return line
• CPC Class Codes: F15B 2211/613 : Feeding circuits
• CPC Class Codes: F15B 2211/633 : representing a state of the prime mover, e.g. torque or rotational speed
• CPC Class Codes: F15B 2211/6333 : representing a state of the pressure source, e.g. swash plate angle
• CPC Class Codes: F15B 2211/6346 : representing a state of input means, e.g. joystick position
• CPC Class Codes: F15B 2211/6355 : having valve means
• CPC Class Codes: F15B 2211/7052 : Single-acting output members
• CPC Class Codes: F15B 2211/7058 : Rotary output members
• CPC Class Codes: F15B 2211/71 : Multiple output members, e.g. multiple hydraulic motors or cylinders

Abstract

A system that can recover flows of a hydraulic pressure fluid returned from a plurality of hydraulic actuators is disclosed which includes a plurality of fluid recovery circuits (15, 19, 25 and 27) into which flows of a hydraulic pressure fluid returned from such a plurality of actuators are admitted, and a main fluid recovery circuit (36). There is provided a selector means (30, 31, 32, 33, 34, 35, 37) for permitting at least one of the plural fluid recovery circuits (15, 19, 25 and 27) selectively to communicate with the main fluid recovery circuit (36). The system, by permitting at least one of a plurality of fluid recovery circuits to communicate with a main fluid recovery circuit, enables a hydraulic return pressure fluid from at least one of a plurality of actuators to be recovered and hence is applicable to a working machine involving a plurality of hydraulic actuators.

Claims

1. A hydraulic actuator return pressure fluid recovery system, comprising:

a plurality of fluid recovery circuits associated with a plurality of hydraulic actuators for accepting flows of a hydraulic pressure fluid returned from said actuators;

a main fluid recovery circuit; and

a selector means for permitting at least one of said plural fluid recovery circuits selectively to communicate with said main fluid recovery circuit, wherein

said selector means is adapted to selectively establish a first state in which any one of said fluid recovery circuits solely lies in fluid communication with said main fluid recovery circuit and a second state in which more than one of said fluid recovery circuits lie in fluid communication with said main fluid recovery circuit, and wherein, when a first fluid recovery circuit of said fluid recovery circuits is in fluid communication with said main fluid recovery circuit, said selector means prevents a second fluid recovery circuit of said fluid recovery circuits from being in communication with said main fluid recover circuit.

2. A hydraulic actuator return pressure fluid recovery system as set forth in claim 1, in which there is provided a back pressure compensating valve connected to only another of the fluid recovery circuits and adapted to permit a hydraulic return pressure fluid flow to pass therethrough selectively upon an influent side fluid pressure thereof exceeding a predetermined level.

3. A hydraulic actuator return pressure fluid recovery system as set forth in claim 1, in which each of said fluid recovery circuit includes an on/off valve, said on/off valve in said fluid recovery circuit in which a pressure occurs due to an external load in said actuator is opened.

4. A hydraulic actuator return pressure fluid recovery system as set forth in claim 2, in which each of said fluid recovery circuit includes an on/off valve, said on/off valve in said fluid recovery circuit in which a pressure occurs due to an external load in said actuator is opened.

5. A hydraulic actuator return pressure fluid recovery system as set forth in claim 1, in which

each of said fluid recovery circuits includes:

an on/off valve operable to be opened in response to a signal that operates a directional control valve to be switched over for supplying said actuator corresponding thereto with a hydraulic pressure fluid; and

said selector means comprises;

a selector valve connected to said second fluid recovery circuit and operable to be opened in response to a signal that operates a directional control valve to be switched over for supplying said actuator corresponding thereto with a hydraulic pressure fluid; and

a priority valve which prevents said second fluid recovery circuit from being in communication with said main fluid recovery circuit, when said first fluid recovery circuit is in fluid communication with said main fluid recovery circuit.

6. A hydraulic actuator return pressure fluid recovery system as set forth in claim 5, in which said selector means further comprises a back pressure compensating valve connected to only another of the fluid recovery circuits and adapted to permit a hydraulic return pressure fluid flow to pass therethrough selectively upon an influent side fluid pressure thereof exceeding a predetermined level.