Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
233 words
A control system for a hydraulic circuit apparatus comprising at least first and second variable displacement types hydraulic pumps, at least first and second hydraulic actuators driven by the first and second pumps, and valve means for controlling hydraulic connections between the hydraulic pumps and the actuators, wherein said control system comprises: means for deciding the order of priority of hydraulic connections between the first actuator and the first and second hydraulic pumps and the order of priority of hydraulic connections between the second hydraulic pump and the first and second actuators; first means for sensing maximization of the displacement volume of the first hydraulic pump; second means for sensing that the displacement volume of the second hydraulic pump has become substantially zero; and means for deciding target displacement volumes of the first and second hydraulic pumps based on information supplied at least by said priority order deciding means and said first and second sensing means whereby when the flow rate of hydraulic fluid supplied to the first actuator is increased, the displacement volume of the second hydraulic pump is increased from substantially zero after the displacement volume of the first hydraulic pump is maximized and, when the flow rate of hydraulic fluid supplied to the first actuator is reduced, the displacement volume of the first hydraulic pump is reduced after the displacement volume of the second hydraulic pump has become substantially zero.
Claim 2
Dependent Claim
233 words
A control system for a hydraulic circuit apparatus comprising at least first and second variable displacement types hydraulic pumps, at least first and second hydraulic actuators driven by the first and second pumps, and valve means for controlling hydraulic connections between the hydraulic pumps and the actuators, wherein said control system comprises: means for deciding the order of priority of hydraulic connections between the first actuator and the first and second hydraulic pumps and the order of priority of hydraulic connections between the second hydraulic pump and the first and second actuators; first means for sensing maximization of the displacement volume of the first hydraulic pump; second means for sensing that the displacement volume of the second hydraulic pump has become substantially zero; and means for deciding target displacement volumes of the first and second hydraulic pumps based on information supplied at least by said priority order deciding means and said first and second sensing means whereby when the flow rate of hydraulic fluid supplied to the first actuator is increased, the displacement volume of the second hydraulic pump is increased from substantially zero after the displacement volume of the first hydraulic pump is maximized and, when the flow rate of hydraulic fluid supplied to the first actuator is reduced, the displacement volume of the first hydraulic pump is reduced after the displacement volume of the second hydraulic pump has become substantially zero.
Claim 3
Dependent Claim
61 words
A control system as claimed in claim 1, wherein said priority order deciding means comprises means for judging whether or not a first operation signal indicative of the operation of the first actuator is greater than a predetermined value, and means for judging whether or not a second operation signal indicative of the operation of the second actuator is substantially zero.
Claim 4
Dependent Claim
132 words
A control system as claimed in claim 1, wherein said target displacement volume deciding means comprises first means for deciding the target displacement volume of the first hydraulic pump based on a first operation signal indicative of the operation of the first actuator, second means for deciding the target displacement volume of the second hydraulic pump based on the first operation signal, third means for deciding the target displacement volume of the second hydraulic pump based on a second operation signal indicative of the operation of the second actuator, and means for selecting, as a target displacement volume of the second hydraulic pump, the target displacement volume decided by the second means when the displacement volume of the first hydraulic pump is maximized and when the second operation signal is substantially zero.
Claim 5
Dependent Claim
48 words
A control system as claimed in claim 3, wherein said target displacement volume deciding means further comprises means for selecting, as a target displacement volume of the second hydraulic pump, the target displacement volume decided by the third means when the second operation signal is not substantially zero.
Claim 6
Dependent Claim
39 words
A control system as claimed in any one of claims 1 - 4, further comprising means for deciding switch timing for said valve means based on information supplied by said priority order judging means and said second sensing means.
Claim 7
Dependent Claim
56 words
A control system as claimed in any one of claims 1 - 4, further comprising means for deciding the rate of changes in the displacement volumes of the first and second hydraulic pumps based on information supplied by said target displacement volume deciding means thereby to prevent the rate of changes from exceeding a predetermined level.