Power plants – Pressure fluid source and motor – Having condition responsive control in a system of distinct...
Reexamination Certificate
1999-10-19
2001-09-04
Ryznic, John E. (Department: 3745)
Power plants
Pressure fluid source and motor
Having condition responsive control in a system of distinct...
Reexamination Certificate
active
06282891
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to a method and system for controlling fluid flow in an electrohydraulic system and, more particularly, to a method and system for controlling the flow of fluid in an electrohydraulic system having multiple hydraulic circuits coupled to a single hydraulic pump.
BACKGROUND ART
Work machines such as wheel type loaders include work implements capable of being moved through a number of positions during a work cycle. Such implements typically include buckets, forks, and other material handling apparatus. Control levers are mounted at the operator's station and are connected to hydraulic circuits associated with each of the implements for moving the implements. The operator must manually move the control levers to open and close hydraulic valves that direct pressurized fluid from a hydraulic pump to hydraulic cylinders that in turn cause the implements to move.
Today, more and more hydraulic circuits are being driven electronically via a solenoid. That is, rather than be driven by fixed mechanical linkages, the hydraulic cylinders are driven by solenoids that are actuated via electronic signals from a microprocessor-controlled controller. Thus, the hydraulic cylinders are controlled via pre-programmed control logic. However, when changes are made to such an electrohydraulic system that affect flow characteristics, such as hose dimensions, orifice sizing, valve conversions, etc., the control logic must be revised accordingly in order to maximize fluid flow.
Accordingly, it is an object of this invention to provide a method and system that automatically calibrates software control in order to maximize hydraulic fluid flow to hydraulic cylinders in an electrohydraulic system.
The present invention is directed to overcome one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
In one aspect of this invention, a method is provided for automatically controlling fluid flow in an electrohydraulic system having multiple hydraulic cylinders, each connected to a single hydraulic pump and a corresponding work implement and having at least two hydraulic circuits associated therewith for receiving the fluid from a supply and moving the cylinders accordingly. The method begins with determining a scaling factor for each of the hydraulic circuits for compensating the hydraulic circuit for receiving less than maximum fluid flow from the pump. An input signal is received representing a desired amount of movement of at least two of the work implements, and a desired percentage of fluid flow to each of the hydraulic circuits associated with each of the cylinders is determined based on the desired amount of movement of the work implements and the scaling factor of the corresponding hydraulic circuits. Finally, the amount of fluid flow from the fluid supply to each of the hydraulic circuits is controlled based on the corresponding desired percentage of fluid flow so as to allow for maximum fluid flow to each of the hydraulic circuits.
In another aspect of the invention, a system is provided for carrying out the steps of the above-described method. The system includes a hydraulic fluid supply coupled to a plurality of hydraulic cylinders via a single hydraulic pump. Each of the cylinders are coupled to corresponding work implements, and have at least two hydraulic circuits associated therewith for receiving the fluid supply and moving the cylinders accordingly. The system further includes at least two input devices for generating at least two corresponding input signals representative of a desired amount of movement for at least two of the work implements. The system also includes a controller, coupled to each of the input devices and each of the cylinders, for determining a scaling factor for each of the hydraulic circuits for compensating the hydraulic circuit for receiving less than maximum fluid flow from the pump, determining a desired percentage of fluid flow to each of the hydraulic circuits associated with each of the cylinders based on the desired amount of movement of the work implements and the scaling factor of the corresponding hydraulic circuits, and for controlling the amount of fluid flow from the hydraulic fluid supply to each of the hydraulic circuits based on the corresponding desired percentage of fluid flow.
REFERENCES:
patent: 4706456 (1987-11-01), Backe et al.
patent: 4712376 (1987-12-01), Hadank et al.
patent: 4759183 (1988-07-01), Kreth et al.
patent: 4856278 (1989-08-01), Widmann et al.
patent: 4881450 (1989-11-01), Hirata et al.
patent: 4967557 (1990-11-01), Izumi et al.
patent: 5167121 (1992-12-01), Sepehri et al.
patent: 5214916 (1993-06-01), Lukich
patent: 5249421 (1993-10-01), Lunzman
patent: 5520087 (1996-05-01), Takamura et al.
patent: 5553452 (1996-09-01), Snow et al.
patent: 5623093 (1997-04-01), Schenkel et al.
patent: 5762475 (1998-06-01), Maddock et al.
patent: 5873244 (1999-02-01), Cobo et al.
patent: 5930996 (1999-08-01), Nakamura et al.
Caterpillar Inc.
Howard & Howard
Ryznic John E.
LandOfFree
Method and system for controlling fluid flow in an... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and system for controlling fluid flow in an..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and system for controlling fluid flow in an... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2449882