Motors: expansible chamber type – Plural relatively movable or rigidly interconnected working... – With means to control the working fluid to one working...
Patent
1989-10-27
1991-12-24
Look, Edward K.
Motors: expansible chamber type
Plural relatively movable or rigidly interconnected working...
With means to control the working fluid to one working...
91459, 60327, 60484, F01L 3100, F15B 15044
Patent
active
050741942
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to hydraulic driving methods of and hydraulic driving apparatuses for hydraulic machines and, particularly, to a hydraulic driving method of and a hydraulic driving apparatus for a hydraulic machine suitable for hydraulic construction machines such as a hydraulic excavator, a hydraulic crane and the like equipped with a plurality of hydraulic actuators, the hydraulic driving method and the hydraulic driving apparatus being capable of optionally selecting at least one of the plurality of hydraulic actuators to optionally alter operational-speed characteristics of the selected respective actuators, that is, maximum values of operational speeds or variation characteristics of the operational speeds.
BACKGROUND ART
A conventional hydraulic machine such as, for example, a hydraulic excavator comprises a hydraulic pump forming a source of hydraulic fluid and driven by rotational power of an engine, a plurality of actuators such as a running motor, a boom cylinder and so on driven by the hydraulic fluid supplied from the hydraulic pump, a plurality of control valves corresponding respectively to the actuators, such as a running-motor control valve, a boom-cylinder control valve and so on for controlling respectively flow directions and flow rates of the hydraulic fluid supplied to the actuators, and a control device for giving control signals respectively to drive sections of the respective control valves for the actuators in response to operational directions and amounts of operation of operating levers arranged correspondingly respectively to the actuators, thereby controlling operations of the respective control valves to bring the actuators respectively to requisite operational states (operational directions and operational speeds) in accordance with various workings.
Generally, the conventional hydraulic driving apparatus is so designed that the maximum opening degrees of the control valves determined at the initial specification cannot subsequently be altered. Accordingly, when the hydraulic driving apparatus is operated in such a state that the operational speeds of the respective actuators are maximum, hydraulic fluid of a predetermined discharge quantity determined by the rotational speed of the engine is supplied from the hydraulic pump to the actuators through the control valves, during a period for which the rotational speed of the engine driving the hydraulic pump is constant, so that the maximum operational speeds of the respective actuators are maintained constant. When it is desired to alter the maximum operational speeds of the actuators, the rotational speed of the engine must be altered to vary the discharge quantity of the hydraulic pump, that is, flow rates of the hydraulic fluid supplied respectively to the actuators. With such a way of altering the maximum operational speeds of the actuators, however, it is impossible to alter the operational speeds of only specific one or some of the plurality of actuators, because the hydraulic fluid from the hydraulic pump is supplied to all the actuators under the same condition.
In the hydraulic machine such as a hydraulic excavator or the like, however, there may occur a case where it is desired to slow down the operational speed of only a specific one of the actuators in accordance with the working contents in view of the actual working. For example, for the hydraulic excavator, there may be a case where such an operation as to draw the bucket horizontally is carried out for ground leveling. In such a case, relatively high working accuracy is required to draw the bucket horizontally toward this side, so that it is desired to slow down the operational speed of only the bucket cylinder or the operational speed of only the arm cylinder. In the conventional hydraulic driving apparatus, however, it is impossible to slow down the operational speeds of only specific some of the plurality of actuators, as described previously. That is, if the rotational speed of the engine is lowered, the operational speeds o
REFERENCES:
patent: 4102132 (1978-07-01), Palmer
patent: 4516469 (1985-05-01), Sato et al.
patent: 4625622 (1986-12-01), Gunda et al.
patent: 4718329 (1988-01-01), Nakajima et al.
patent: 4768339 (1988-09-01), Aoyagi et al.
patent: 4773302 (1988-09-01), Mizota et al.
patent: 4800721 (1989-01-01), Cemenska et al.
patent: 4811561 (1989-03-01), Edwards et al.
Haga Masakazu
Hirata Toichi
Sugiyama Genroku
Tanaka Hideaki
Yoshida Kuniaki
Hitachi Construction Machinery Co. Ltd.
Look Edward K.
Nguyen Hoang
LandOfFree
Hydraulic driving method of and hydraulic driving apparatus for 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 driving method of and hydraulic driving apparatus for , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hydraulic driving method of and hydraulic driving apparatus for will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-37520