Power plants – Pressure fluid source and motor – Having condition responsive control in a system of distinct...
Patent
1990-03-14
1992-07-07
Look, Edward K.
Power plants
Pressure fluid source and motor
Having condition responsive control in a system of distinct...
60430, F16D 3102
Patent
active
051272270
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
This invention relates to a hydraulic circuit apparatus for use in construction vehicles provided with a hydraulic circuit for power steering and a hydraulic circuit for implements and, more particularly, to a hydraulic circuit apparatus for construction vehicles arranged such that pressurized fluid in an amount more than that required for power steering is allowed to join the fluid flow to be supplied into the hydraulic circuit for implements thereby increasing the operating speed of the implements.
BACKGROUND ART OF THE INVENTION
One embodiment of a prior art hydraulic circuit apparatus for use in construction vehicles is shown in FIG. 1.
As shown in FIG. 1, this hydraulic circuit apparatus comprises a plurality of hydraulic pumps P.sub.1, P.sub.2 and P.sub.3 for supplying pressurized fluid, and a flow control valve 6 which serves to allow the pressurized fluid in an excess amount than that required for a hydraulic circuit 5 for power steering to join the fluid flow through a hydraulic circuit A for implements. Reference characters c and d denote valves for operating the implements and are adapted for controlling the supply of pressurized fluid to hydraulic cylinders 22 and 23 for actuating the implements. Reference character e denotes a main relief valve, and T reference character a fluid tank or reservoir.
To improve the maneuverability of the implements in the above-mentioned prior art hydraulic circuit apparatus shown in FIG. 1, there is a conventional hydraulic circuit B for implements as shown in FIG. 2. The hydraulic circuit B comprises, in addition to the hydraulic circuit A for implements shown in FIG. 1, implement operating valves 7 and 8 and pressure compensating flow control valves 9 and 10 associated, respectively, therewith. In FIG. 2, reference numerals 9' and 10' indicate springs and numerals 15, 16, 17 and 18 indicate pilot pipings.
Further, in the case where the hydraulic circuit for implements is kept at a high pressure and large quantities of pressurized fluid is not required for the hydraulic circuit for implements, a prior art arrangement as shown in FIG. 3 is used. An unloading valve c is used to unload the pressurized fluid in excess of that required for the hydraulic circuit 5 for power steering upstream of the hydraulic circuit for implements A and B. This thereby reduces the power consumption for the latter.
In the case where the above-mentioned prior techniques are used, the problems are as follows.
(1) In the case where the pressure compensating flow control valves 9 and 10 are additionally provided as shown in FIG. 2, when the hydraulic circuit for implements is at its neutral position (stating more specifically, the implement operating valves 7 and 8 assume their positions 7.sub.2 and 8.sub.2, respectively), it is required to provide a fluid actuating pressure which can overcome the resilient forces of the springs 9' and 10' in the pressure compensating flow control valves 9 and 10, respectively. This fluid pressure is produced in the pilot pipings 15, 17, thus causing pressure losses corresponding to the fluid actuating pressure.
(2) In the above-mentioned prior art hydraulic circuit apparatuses shown in the FIGS. 1 and 2, in case where the flow rate of fluid under pressure delivered by the hydraulic pump P.sub.1 meets the requirements of the hydraulic circuit A or B for implements, the pressurized fluid in an excess amount or a flow rate than that supplied into the hydraulic circuit 5 for power steering becomes useless. The fluid pressure for the hydraulic circuit for implements becomes loaded on the hydraulic pump P.sub.2 or P.sub.3, thus causing a high power consumption for the latter.
(3) In the above-mentioned prior art hydraulic circuit apparatuses shown in FIGS. 1, 2 and 3, because of a high rate of fluid flow through the implement operating valves (c, d in FIG. 1, and 7, 8 in FIG. 3), there is a tendency of causing a rise in fluid temperature and generating noise due to the fluid pressure.
SUMMARY OF THE INVENTION
The present
REFERENCES:
patent: 3720059 (1973-03-01), Schurowski et al.
patent: 3868821 (1975-03-01), Ratliff et al.
patent: 3916624 (1975-11-01), Machens et al.
patent: 3975909 (1976-08-01), McBurnett
patent: 3987623 (1976-10-01), Bianchetta
patent: 4030623 (1977-06-01), Bridwell et al.
patent: 4461148 (1984-07-01), Krusche
patent: 4864822 (1989-09-01), Wachs et al.
Kabushiki Kaisha Komatsu Seisakusho
Kananen Ronald P.
Look Edward K.
Lopez F. Daniel
LandOfFree
Hydraulic circuit apparatus for construction vehicles 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 apparatus for construction vehicles, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hydraulic circuit apparatus for construction vehicles will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1822508