Power plants – Pressure fluid source and motor – Having condition responsive control in a system of distinct...
Patent
1992-07-22
1993-11-09
Look, Edward K.
Power plants
Pressure fluid source and motor
Having condition responsive control in a system of distinct...
60426, 60468, 91518, 91445, 91447, F16D 3102
Patent
active
052591921
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
This invention relates to a hdyraulic circuit system for supplying fluid under pressure discharged by a single hyraulic pump into a plurality of hydraulic actuators, and more particularly to a hydraulic circuit system which can reduce the flow rate distribution error in supplying pressurized fluid into the plurality of hydraulic actuators.
BACKGROUND ART OF THE INVENTION
To supply fluid under pressure discharged by a single hydraulic pump into a plurality of hydraulic actuators, it is only necessary to provide a plurality of operating valves and construct a hydraulic circuit system so as to supply pressurized fluid into each of the hydraulic actuators by switching over the operating valves. In such a circuit system thus constructed, when pressurized fluid is supplied into a plurality of actuators at the same time, pressurized fluid is supplied only into hydraulic actuators with low loading thereon, but not supplied into those with high loading thereon.
As a hydraulic circuit system which overcomes this disadvantage, the system shown, for example, in the publication of Japanese Patent No. HEI 2-49405 has been proposed.
A schematic diagram of such a hydraulic circuit system is shown in FIG. 7.
Stating in brief, a hydraulic pump 1 has a discharge conduit 1a which is provided with a plurality of operating valves 2, and pressure compensating valves 5 are provided in circuits 4 connecting the operating valves 2 with hydraulic actuators 3, respectively. The arrangement is made such that when the operating valves 2 are operated at the same time the hydraulic actuators 3 can be supplied with pressurized fluid at a flow-rate distribution ratio proportional to the ratio in the area of openings of operating valves 2 by detecting the pressure in each of the circuits 4, that is, a highest value of the load pressures by means of check valves 6, and applying the detected pressure to each of pressure compensating valves 5 to set it at a pressure corresponding to the load pressure, thereby equalizing the pressures on the outlet sides of the operating valves 2.
In such a hydraulic circuit system, a flow rate distribution of pressurized fluid proportional to ratio in the area of openings of the operating valves 2 is obtained by the functions of the pressure compensating valves 5 irrespective of the magnitude of loading on each hydraulic actuator 3 so that the pressurized fluid discharged by the single hydraulic pump 1 can be supplied into the hydraulic actuators 3 at a flow-rate distribution ratio proportional to the ratio in the manipulated variables of the operating valves 2.
However, since the load pressures on the hdyraulic actuators 3 are detected and compared on the outlet sides of the pressure compensating valves 5, and then a highest pressure of the load pressure is introduced into pressure receiving portions 5a which serve to increase the setting pressure of the pressure compensating valves 5, the detected pressure Pa is lower than the inlet pressure P.sub.6 by a value corresponding to the pressure loss of fluid passing through each pressure compensating valve 5. As a result, the flow rates of pressurized fluid passing through the pressure compensating valves 5 are accompanied by an error corresponding to the pressure loss, thereby causing a flow rate distribution error.
Stating in brief, the flow rate Q.sub.1 of pressurized fluid passing through the pressure compensating valve 5 with a low load pressure thereon and the flow rate Q.sub.2 of pressurized fluid passing through the pressure compensating valve 5 with a high load pressure thereon can be expressed by the following equations. ##EQU1##
Wherein C is a constant, a.sub.1 and a.sub.2 are the areas of openings of operating valves, and Pc is the discharge pressure.
Therefore, an error corresponding to the pressure loss (Pb-Pa) through each pressure compensating valve 5 occurs in the respective flow rates.
Further, the above-mentioned problem can be solved by detecting the load pressures on the inlet sides of the pressure compens
REFERENCES:
patent: 5188147 (1993-02-01), Shiria et al.
Akiyama Teruo
Karakama Tadao
Kabushiki Kaisha Komatsu Seisakusho
Kananen Ronald P.
Look Edward K.
Lopez F. Daniel
LandOfFree
Hydraulic circuit system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hydraulic circuit system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hydraulic circuit system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1134992