FLUID PRESSURE CIRCUIT

• US 20090159143A1
• Filed: 02/20/2007
• Published: 06/25/2009
• Est. Priority Date: 07/31/2006
• Status: Active Grant

• Current Assignee: Caterpillar Sarl (Caterpillar Incorporated)
• Original Assignee: Shin Caterpillar Mitsubishi Ltd. (Caterpillar Incorporated)
• Inventors: Nishikawa, Hiroyasu, Shimahara, Sei
• Granted Patent: US 7,958,907 B2
• Time in Patent Office: Days
• US Class Current: 137/625.640
• CPC Class Codes: E02F 9/2228 including an electronic controller
• CPC Class Codes: E02F 9/2235 including an electronic controller
• CPC Class Codes: E02F 9/2242 including an electronic controller
• 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 11/055 by adjusting the pump output or bypass
• CPC Class Codes: F15B 11/16 with two or more servomotors
• CPC Class Codes: F15B 11/17 using two or more pumps
• CPC Class Codes: F15B 2211/20546 variable capacity
• CPC Class Codes: F15B 2211/20576 with multiple pumps
• CPC Class Codes: F15B 2211/329 actuated by fluid pressure
• CPC Class Codes: F15B 2211/40515 with variable throttles or orifices
• 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 2211/6313 the pressure being a load pressure
• CPC Class Codes: F15B 2211/6355 having valve means
• CPC Class Codes: F15B 2211/7142 the output members being arranged in multiple groups
• CPC Class Codes: F15B 2211/78 Control of multiple output members
• CPC Class Codes: Y10T 137/86614 Electric
• CPC Class Codes: Y10T 137/87209 Electric

Abstract

A fluid pressure circuit that can, in either case where a first actuator that is fed from a first pump or a second actuator that is fed from a second pump is operated, by allowing feeding of the hydraulic fluid to a specific actuator from either the first or second pump, improve interlockability with the specific actuator. A control valve is incorporated with a plurality of first-group spools fed from a drive pump and a plurality of second-group spools fed from an idle pump. A solenoid selector valve unit switches a pilot line of a second-group tool controlling spool to a communicating state at the time of detection of a spool operation by a first pressure switch and switches a pilot line of a first-group tool controlling spool to a communicating state at the time of detection of a spool operation by a second pressure switch.

Claims

1. A fluid pressure circuit comprising:

a control valve incorporated with a plurality of first-group spools fed with hydraulic fluid from a first pump and a plurality of second-group spools fed with hydraulic fluid from a second pump, capable of feeding the hydraulic fluid to a specific actuator through a first-group specific spool and a second-group specific spool, capable of feeding the hydraulic fluid to a first actuator through another first-group spool, and capable of feeding the hydraulic fluid to a second actuator through another second-group spool;

a pilot valve that pilot-operates each spool of the control valve via a pilot line;

a first detector that detects operation of another first-group spool of the control valve;

a second detector that detects operation of another second-group spool of the control valve; and

a solenoid selector valve unit that switches a pilot line of the specific second-group spool from an interrupting state to a communicating state at a time of detection of a spool operation by the first detector and switches a pilot line of the specific first-group spool from an interrupting state to a communicating state at a time of detection of a spool operation by the second detector.

2. The fluid pressure circuit as set forth in claim 1, wherein the solenoid selector valve unit is provided with four solenoid selector valves corresponding to two pilot lines connected to both ends of the specific first-group spool and two pilot lines connected to both ends of the specific second-group spool, respectively.

3. The fluid pressure circuit as set forth in claim 2, wherein the solenoid selector valve is a proportional solenoid valve that is displaced according to an input electrical signal.

4. The pressure circuit as set forth in claim 1, wherein

the first actuator is a boom cylinder that operates a boom of work equipment in a work machine;

the second actuator is a stick cylinder that operates a stick coupled to a front end of the boom; and

the specific actuator is a tool actuator that operates an attachment tool coupled to a front end of the stick.