Safety Device For Hydraulic Working Machine

• US 20100100274A1
• Filed: 02/28/2008
• Published: 04/22/2010
• Est. Priority Date: 02/28/2007
• Status: Active Grant

• Current Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Inventors: Satake, Hidetoshi, Ichimura, Kazuhiro, Gotou, Yuuki, Kodaka, Katsuaki, Nagashima, Yuuji
• Granted Patent: US 8,554,401 B2
• Time in Patent Office: Days
• US Class Current: 701/29
• CPC Class Codes: E02F 9/226 Safety arrangements, e.g. hydraulic driven fans, preventing cavitation, leakage, overheating
• CPC Class Codes: E02F 9/2285 Pilot-operated systems
• CPC Class Codes: F15B 19/005 Fault detection or monitoring
• CPC Class Codes: F15B 20/002 Electrical failure
• CPC Class Codes: F15B 20/008 Valve failure
• CPC Class Codes: F15B 2211/327 electrically or electronically
• CPC Class Codes: F15B 2211/329 actuated by fluid pressure
• CPC Class Codes: F15B 2211/355 Pilot pressure control
• CPC Class Codes: F15B 2211/36 Pilot pressure sensing
• CPC Class Codes: F15B 2211/50518 using pressure relief valves
• CPC Class Codes: F15B 2211/50536 using unloading valves controlling the supply pressure by diverting fluid to the return line
• CPC Class Codes: F15B 2211/50554 the pressure control means controlling a pressure downstream of the pressure control means, e.g. pressure reducing valve
• CPC Class Codes: F15B 2211/55 for limiting a pressure up to a maximum pressure, e.g. by using a pressure relief valve
• CPC Class Codes: F15B 2211/575 Pilot pressure control
• CPC Class Codes: F15B 2211/6316 the pressure being a pilot pressure
• 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 2211/67 Methods for controlling pilot pressure
• CPC Class Codes: F15B 2211/855 Testing of fluid pressure systems
• CPC Class Codes: F15B 2211/857 Monitoring of fluid pressure systems
• CPC Class Codes: F15B 2211/8636 : Circuit failure, e.g. valve or hose failure
• CPC Class Codes: F15B 2211/87 : Detection of failures

Abstract

There are provided: control valves 22-24 that control flow of pressure oil from the hydraulic source 21 to the hydraulic actuators 15-17; electric lever devices 51-53 that output electrical operation signals v51-v53 in correspondence to lever operation; electromagnetic proportional valves 25-30 through which control pressures for controlling the control valves 22-24 are output; a pressure calculating unit 50 that calculates control pressures P25-P30 in correspondence to the operation signals V51-v53; a control unit 50 that controls the electromagnetic proportional valves 25-30 so that control pressures to be output from the electromagnetic proportional valves 25-30 become the control pressures P25-P30 that have been calculated; a high-pressure selection circuit 41-44 that selects a higher pressure between control pressures that have been output from the electromagnetic proportional valves 25-30; pressure detectors 45 and 46 that detect a control pressure selected by the high-pressure selection circuit 41-44; an abnormality determination unit 50 that determines an abnormality in the electromagnetic proportional valves 25-30 based upon the control pressure detected by the pressure detectors 45 and 46 and the control pressure calculated by the pressure calculating unit; and an inhibiting device 47 and 48 that prohibits control of the control valves 22-24 when it is determined that an abnormality has occurred in the electromagnetic proportional valves 25-30.

Claims

1. A safety device for hydraulic working machine, comprising:

a hydraulic source;

a hydraulic actuator that is driven by pressure oil from the hydraulic source;

a control valve that controls a flow of pressure oil from the hydraulic source to the hydraulic actuator;

an electric lever device that outputs an electrical operation signal, which is a drive instruction for the hydraulic actuator, in correspondence to lever operation;

first and second electromagnetic proportional valves through which control pressures for controlling the control valve are output;

a pressure calculating unit that calculates first and second control pressures in correspondence to an operation signal that is output from the electric lever device;

a control unit that controls the first and second electromagnetic proportional valves so that control pressures to be output from the first and second electromagnetic proportional valves become the first and second control pressures that have been calculated by the pressure calculating unit;

a high-pressure selection circuit that selects a higher pressure between control pressures that have been output from the first and second electromagnetic proportional valves;

a pressure detector that detects a control pressure selected by the high-pressure selection circuit;

an abnormality determination unit that determines an abnormality in the first and second electromagnetic proportional valves based upon the control pressure detected by the pressure detector and the first and second control pressure calculated by the pressure calculating unit; and

an inhibiting device that prohibits the first and second electromagnetic proportional valves from controlling the control valve when the abnormality determination unit determines that an abnormality has occurred in the first and second electromagnetic proportional valves.

2. A safety device for hydraulic working machine, comprising:

a hydraulic source;

at least first and second hydraulic actuators that are driven by pressure oil from the hydraulic source;

first and second control valves that control flow of pressure oil from the hydraulic source to the first and second hydraulic actuators;

first and second electric lever devices that output electrical operation signals, which are drive instructions for the first hydraulic actuator and the second hydraulic actuator respectively, in correspondence to lever operation;

first and second electromagnetic proportional valves through which control pressures for controlling the first control valve are output;

third and fourth electromagnetic proportional valves through which control pressures for controlling the second control valve are output;

a pressure calculating unit that calculates a first and second control pressures in correspondence to an operation signal that is output from the first electric lever device, and calculates a third and fourth control pressures in correspondence to an operation signal that is output from the second electric lever device;

a control unit that controls the first and second electromagnetic proportional valves so that control pressures to be output from the first and second electromagnetic proportional valves become the first and second control pressures that have been calculated by the pressure calculating unit, and controls the third and fourth electromagnetic proportional valves so that control pressures to be output from the third and fourth electromagnetic proportional valves become the third and fourth control pressures that have been calculated by the pressure calculating unit;

a first high-pressure selection circuit that selects a higher pressure between control pressures that have been output from the first and second electromagnetic proportional valves;

a second high-pressure selection circuit that selects a higher pressure between control pressures that have been output from the third and fourth electromagnetic proportional valves;

a first pressure detector that detects a control pressure selected by the first high-pressure selection circuit;

a second pressure detector that detects a control pressure selected by the second high-pressure selection circuit;

an abnormality determination unit that determines an abnormality in the first and second electromagnetic proportional valves based upon the control pressure detected by the first pressure detector and the first and second control pressures calculated by the pressure calculating unit, and determines an abnormality in the third and fourth electromagnetic proportional valves based upon the control pressure detected by the second pressure detector and the third and fourth control pressures calculated by the pressure calculating unit; and

an inhibiting device that prohibits the first and second electromagnetic proportional valves from controlling the first control valve when the abnormality determination unit determines that an abnormality has occurred in the first and second electromagnetic proportional valves, and prohibits the third and fourth electromagnetic proportional valves from controlling the second control valve when the abnormality determination unit determines that an abnormality has occurred in the third and fourth electromagnetic proportional valves.

3. A safety device for hydraulic working machine, comprising:

a hydraulic source;

at least first and second hydraulic actuators that are driven by pressure oil from the hydraulic source;

first and second control valves that control flow of pressure oil from the hydraulic source to the first and second hydraulic actuators;

first and second electric lever devices that output electrical operation signals, which are drive instructions for the first hydraulic actuator and second hydraulic actuator respectively, in correspondence to lever operation;

first and second electromagnetic proportional valves through which control pressures for controlling the first control valve are output;

third and fourth electromagnetic proportional valves through which control pressures for controlling the second control valve are output;

a pressure calculating unit that calculates first and second control pressures in correspondence to an operation signal that is output from the first electric lever device, and calculates third and fourth control pressures in correspondence to an operation signal that is output from the second electric lever device;

a control unit that controls the first and second electromagnetic proportional valves so that control pressures to be output from the first and second electromagnetic proportional valves become the first and second control pressures that have been calculated by the pressure calculating unit, and controls the third and fourth electromagnetic proportional valves so that control pressures to be output from the third and fourth electromagnetic proportional valves become the third and fourth control pressures that have been calculated by the pressure calculating unit;

a high-pressure selection circuit that selects a maximum control pressure from among control pressures that have been output from the first to fourth electromagnetic proportional valves;

a pressure detector that detects a control pressure selected by the high-pressure selection circuit;

an abnormality determination unit that determines an abnormality in the first to fourth electromagnetic proportional valves based upon the control pressure detected by the pressure detector and the first to fourth control pressures calculated by the pressure calculating unit; and

an inhibiting device that prohibits the first to fourth electromagnetic proportional valves from controlling the first and second control valves when the abnormality determination unit determines that an abnormality has occurred in the first to fourth electromagnetic proportional valves.

4. A safety device for hydraulic working machine, comprising:

a hydraulic source;

at least first, second, and third hydraulic actuators that are driven by pressure oil from the hydraulic source;

first, second, and third control valves that control flow of pressure oil from the hydraulic source to the first, second, and third hydraulic actuators, respectively;

first, second, and third electric lever devices that output electrical operation signals, which are drive instructions for the first, second, and third hydraulic actuators respectively, in correspondence to lever operation;

first and second electromagnetic proportional valves through which control pressures for controlling the first control valve are output;

third and fourth electromagnetic proportional valves through which control pressures for controlling the second control valve are output;

fifth and sixth electromagnetic proportional valves through which control pressures for controlling the third control valve are output;

a pressure calculating unit that calculates first and second control pressures in correspondence to an operation signal that is output from the first electric lever device, third and fourth control pressures in correspondence to an operation signal that is output from the second electric lever device, and fifth and sixth control pressures in correspondence to an operation signal that is output from the third electric lever device;

a control unit that controls the first to sixth electromagnetic proportional valves so that control pressures to be output from the first to sixth electromagnetic proportional valves respectively become the first to sixth control pressures that have been calculated by the pressure calculating unit;

a first high-pressure selection circuit that selects a maximum control pressure from among control pressures that have been output from the first to fourth electromagnetic proportional valves;

a second high-pressure selection circuit that selects a higher pressure between control pressures that have been output from the fifth and sixth electromagnetic proportional valves;

a first pressure detector that detects the control pressure selected by the first high-pressure selection circuit;

a second pressure detector that detects the control pressure selected by the second high-pressure selection circuit;

an abnormality determination unit that determines an abnormality in the first to fourth electromagnetic proportional valves based upon the control pressure detected by the first pressure detector and the first to fourth control pressures calculated by the pressure calculating unit, and determines an abnormality in the fifth and sixth electromagnetic proportional valves based upon the control pressure detected by the second pressure detector and the fifth and sixth control pressures calculated by the pressure calculating unit; and

an inhibiting device that prohibits the first to fourth electromagnetic proportional valves from controlling the first and second control valves when the abnormality determination unit determines that an abnormality has occurred in the first to fourth electromagnetic proportional valves, and prohibits the fifth and sixth electromagnetic proportional valves from controlling the third control valve when the abnormality determination unit determines that an abnormality has occurred in the fifth and sixth electromagnetic proportional valves.

5. A safety device for hydraulic working machine according to claim 4, wherein:

the first and second hydraulic actuators are actuators for performing one operation, whereas the third hydraulic actuator is an actuator for performing another operation.

6. A safety device for hydraulic working machine according to claim 5, wherein:

the hydraulic working machine includes an undercarriage, a revolving superstructure, a work front that is rotatably supported by the revolving superstructure, and a working attachment that is removably attached to the work front; and

the first and second hydraulic actuators are driving actuators for the working attachment.