Fluid handling – Systems – Dividing into parallel flow paths with recombining
Reexamination Certificate
1999-12-30
2001-06-05
Hepperle, Stephen M. (Department: 3753)
Fluid handling
Systems
Dividing into parallel flow paths with recombining
C137S599080, C137S601140, C137S625320, C251S016000
Reexamination Certificate
active
06240959
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to safety devices for hydraulic systems. More specifically, the invention relates to a hydraulic velocity fuse safety device operable to selectively protect systems which may function at any of several selected fluid flow rate settings.
Heretofore hydraulic fuses have been used, for example, in aircraft systems to prevent the escape of hydraulic fluid in the event of a rupture somewhere in the closed hydraulic system. Such fuses are configured so that the fluid flow passage is closed when a selected rate of fluid flow in the line is exceeded. Such existing devices are useful in systems which operate only at one selected rate of flow of hydraulic fluid.
Hydraulic systems typically in use, such as those used on mobile truck mounted systems, however, suffer from the lack of appropriate protective devices. Thus, in the event a hydraulic hoist is used, a 25 to 50 gallons per minute of hydraulic fluid flow is required. Subsequently, after a worker has been elevated to a selected height, a portable tool operated by the same hydraulic system may be needed. Such a tool, however, may require a hydraulic fluid flow rate of only five to ten gallons per minute. On many jobs it is necessary to work, alternately, with tools requiring different fluid flow rates. It has been impractical to protect such systems with prior art hydraulic fuses, particularly in view of the fact that the hydraulic fluid flow rate varies greatly when the engine rpm's on host vehicle are increased. Thus, a 10 gpm fuse would not protect workers using a 50 gpm tool.
Often, when a hydraulic hose ruptures, the hot hydraulic fluid in the system escapes in the form of a hot oil spray. This escaping hot hydraulic fluid may severely burn the affected workers and also may be sprayed into the surrounding area with resultant environmental damage. A great need has thus existed for improved safety devices for such hydraulic systems.
SUMMARY OF THE INVENTION
It is an important object of the present invention to provide protective devices for hydraulic fluid systems which will safely stop the escape of hydraulic fluid from a system in the event of a leak or rupture. An important related object is to provide such protective devices which can be selectively operated to prevent escape of hydraulic fluid at any one of several selected maximum flow rates. The selected maximum flow rates are dependent upon the requirements of the particular system and the particular accessories operated in connection therewith. A further aspect of the invention provides that multiple protective devices are mounted within a single housing. In accordance with a yet further aspect of the invention a housing which contains a plurality of protective fuse devices is provided a valve assembly which enables the use of any selected one of the fuse devices.
In accordance with a further related aspect of the invention a number of hydraulic fuse devices of varying gallon per minute flow ratings are mounted in parallel within a single housing block within individual fluid flow channels therein. In accordance with a still further related aspect of the invention each fluid flow channel within the housing block may be selectively shut off by means of a valve within the channel.
In accordance with one embodiment of the invention, a valve arrangement is provided which allows one single hydraulic flow fuse device to be in an open fluid flow channel while simultaneously closing all of the other parallel fluid flow channels within the block, thereby enabling the selection of a protective hydraulic fuse suitable to allow operation of a selected hydraulically operated attachment, thus protecting the hydraulic system against excessive flow rates which might occur in the event of a rupture or other cause of overspeeding.
In accordance with another embodiment of the invention, electrically controllable valves may be provided with a control system configured to enable opening of a single flow channel while closing all other flow channels.
Briefly, the invention provides a protective device for a hydraulic system which includes a block that forms a housing with at least one fluid flow inlet into the housing and at least one fluid flow outlet. A plurality of fluid flow channels within the housing connect the inlet and the outlet. Each of the fluid flow channels contains a hydraulic fuse adapted to close its associated fluid flow channel when a selected flow rate of hydraulic fluid is exceeded, each of the fuses having a different selected fluid flow rate which causes closure thereof. A valve in each of the fluid flow channels provides for selectively opening and closing the fluid flow channels so that a selected one of the channels is open and all others of the channels are closed. The valves may be integral with a single rotatable stem, or of various alternative designs, for example, electronically controlled valves.
Further objects and advantages of the invention will be apparent from the accompanying claims, the following detailed description and the accompanying drawings.
REFERENCES:
patent: 3494375 (1970-02-01), Henaughan
patent: 4256100 (1981-03-01), Levy et al.
patent: 4819688 (1989-04-01), Field
patent: 5076321 (1991-12-01), Terry
patent: 5313871 (1994-05-01), Kaneko et al.
patent: 5603352 (1997-02-01), Tavor
Hepperle Stephen M.
Krishnamurthy Ramesh
Ryan Kromholz & Manion S.C.
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