Hydraulic Drive System for work machine

• US 10,344,458 B2
• Filed: 06/01/2016
• Issued: 07/09/2019
• Est. Priority Date: 06/09/2015
• Status: Active Grant

• Current Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi Construction Machinery Company Limited (Hitachi, Ltd.)
• Inventors: Hijikata, Seiji, Ishikawa, Kouji, Imura, Shinya
• Primary Examiner(s): Trivedi, Atul
• Application Number:
  US15/554,118
• Publication Number:
  US 20180066416A1
• Time in Patent Office: 1,133 Days
• Field of Search: 701 50
• CPC Class Codes: E02F 9/2203 Arrangements for controlling the attitude of actuators, e.g. speed, floating function
• CPC Class Codes: E02F 9/2217 with energy recovery arrangements, e.g. using accumulators, flywheels
• 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: E02F 9/268 with failure correction follow-up actions
• CPC Class Codes: F15B 19/005 Fault detection or monitoring
• CPC Class Codes: F15B 20/00 Safety arrangements for fluid actuator systems; Applications of safety devices in fluid actuator systems; Emergency measures for fluid actuator systems
• CPC Class Codes: F15B 20/002 Electrical failure
• CPC Class Codes: F15B 20/004 Fluid pressure supply failure
• CPC Class Codes: F15B 20/007 Overload
• CPC Class Codes: F15B 21/14 Energy-recuperation means
• CPC Class Codes: F15B 2211/20546 variable capacity
• CPC Class Codes: F15B 2211/20576 with multiple pumps
• CPC Class Codes: F15B 2211/3058 having additional valves for interconnecting the fluid chambers of a double-acting actuator, e.g. for regeneration mode or for floating mode directional control valves having a regenerative position F15B2211/3133; directional control valves having a floating position F15B2211/3127
• CPC Class Codes: F15B 2211/30595 with additional valves between the groups of valves for multiple output members
• CPC Class Codes: F15B 2211/6309 the pressure being a pressure source supply pressure
• CPC Class Codes: F15B 2211/6313 the pressure being a load pressure
• CPC Class Codes: F15B 2211/6316 the pressure being a pilot pressure
• CPC Class Codes: F15B 2211/6652 Control of the pressure source, e.g. control of the swash plate angle
• CPC Class Codes: F15B 2211/7053 : Double-acting output members
• CPC Class Codes: F15B 2211/7142 : the output members being arranged in multiple groups
• CPC Class Codes: F15B 2211/761 : Control of a negative load, i.e. of a load generating hydraulic energy
• CPC Class Codes: F15B 2211/862 : the abnormal condition being electric or electronic failure
• CPC Class Codes: F15B 2211/8636 : Circuit failure, e.g. valve or hose failure
• CPC Class Codes: F15B 2211/87 : Detection of failures
• CPC Class Codes: F15B 2211/8752 : Emergency operation mode, e.g. fail-safe operation mode
• CPC Class Codes: F15B 2211/88 : Control measures for saving energy

Abstract

A hydraulic drive system 100A for a work machine includes: a boom cylinder 4; an arm cylinder 8; a hydraulic pump device 51; a control valve 5; a regenerative device 61; a first operation device 41; a second operation device 42; a sensor device 71; and a controller 27. The sensor device 71 includes at least one of pressure sensors 23, 24, 25, and 26. The controller 27 includes an abnormality detection part 142 and a first control part. The abnormality detection part 142 determines whether or not the sensor device 71 is abnormal. If the sensor device 71 is abnormal, the first control part controls the regenerative device 61 such that the hydraulic fluid returning from the boom cylinder 4 is not supplied to the arm cylinder 8 even if the values measured by the sensor device 71 satisfy regenerative conditions.

Claims

1. A hydraulic drive system for a work machine, the system comprising:

a boom cylinder;

an arm cylinder;

a hydraulic pump device configured to supply hydraulic fluid to the boom cylinder and the arm cylinder;

a control valve configured to adjust a flow rate of the hydraulic fluid returning from the boom cylinder;

a regenerative device configured to supply the hydraulic fluid returning from a bottom side of the boom cylinder to the arm cylinder;

a first operation device configured to operate the boom cylinder;

a second operation device configured to operate the arm cylinder;

a sensor device including at least one of a first operation amount sensor configured to measure an operation amount of the first operation device, a second operation amount sensor configured to measure an operation amount of the second operation device, a first pressure sensor configured to measure a pressure of the bottom side of the boom cylinder, and a second pressure sensor configured to measure a pressure between the hydraulic pump device and the arm cylinder; and

a controller configured to determine whether the sensors included in the sensor device are abnormal or not and control the regenerative device such that the hydraulic fluid returning from the bottom side of the boom cylinder is supplied to the arm cylinder when the sensors are all determined to be normal and values measured by the sensors satisfy regenerative conditions that are required to be met when the hydraulic fluid returning from the bottom side of the boom cylinder is supplied to the arm cylinder and such that, when any one of the sensors is determined to be abnormal, the hydraulic fluid returning from the bottom side of the boom cylinder is not supplied to the arm cylinder even if the values measured by the sensor device satisfy the regenerative conditions.

2. The hydraulic drive system for a work machine according to claim 1,

wherein the controller is further configured to control the hydraulic pump device such that when the sensors are all determined to be normal and the values measured by the sensors satisfy the regenerative conditions, the delivery flow rate of the hydraulic pump device is reduced on the basis of a regeneration flow rate at which the hydraulic fluid returning from the bottom side of the boom cylinder is supplied to the arm cylinder and, when the any one of the sensors is determined to be abnormal, cancels the control for reducing the delivery flow rate of the hydraulic pump device even if the values measured by the sensors satisfy the regenerative conditions.

3. The hydraulic drive system for a work machine according to claim 1,

wherein the regenerative device is a directional control valve having a port through which the hydraulic fluid returning from the bottom side of the boom cylinder is supplied to the arm cylinder and a port through which the hydraulic fluid returning from the bottom side of the boom cylinder is discharged to the control valve.

4. The hydraulic drive system for a work machine according to claim 1,

wherein the regenerative device includes:

a regenerative passage for supplying the hydraulic fluid returning from the bottom side of the boom cylinder to the arm cylinder;

a regenerative valve configured to adjust the flow rate of the hydraulic fluid in the regenerative passage;

a first solenoid valve configured to control the regenerative valve hydraulically; and

a second solenoid valve of a normally-open type configured to receive a first pilot pressure corresponding to the operation amount of the first operation device and output to the control valve a second pilot pressure which is obtained by reducing the first pilot pressure for controlling the control valve with the second pilot pressure and

wherein the controller is further configured to control the second solenoid valve such that when the sensors are all determined to be normal and the values measured by the sensors satisfy the regenerative conditions, the first pilot pressure is reduced and such that when the any one of the sensors is determined to be abnormal, the first pilot pressure is not reduced even if the values measured by the sensors satisfy the regenerative conditions.

5. The hydraulic drive system for a work machine according to claim 1,

wherein the first operation amount sensor, the second operation amount sensor, the first pressure sensor, and the second pressure sensor included in the sensor device are pressure sensors that output electric signals that match measured pressures and

wherein the controller is configured to determine the presence of an abnormality when any of the electric signals output by the pressure sensors becomes lower than a predetermined lower limit value or higher than a predetermined upper limit value.