Motors: expansible chamber type – Working member position responsive motive fluid control – Exhaust control
Reexamination Certificate
1999-04-05
2001-02-13
Ryznic, John E. (Department: 3745)
Motors: expansible chamber type
Working member position responsive motive fluid control
Exhaust control
C091S422000
Reexamination Certificate
active
06186043
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is directed to a cushion hydraulic cylinder wherein metering orifices to control the speed of the piston are located in the cylinder and the piston.
2. Description of the Prior Art
Hydraulic cylinders comprise a cylindrical tube into which a piston is located for reciprocating back and forth in the piston in response to fluid pressure. The piston is provided with a rod that projects out of the cylindrical tube. Single acting hydraulic cylinders have a single hydraulic port directing fluid to the hydraulic cylinder. The piston is returned to its original position by a spring or some other suitable biassing mechanism when the fluid pressure is released. In double acting hydraulic cylinders each side of the piston is provided with a source of hydraulic pressure so that the piston is positively driven by the hydraulic pressure in both directions. In many applications the piston is provided with poppet valves which short circuit the flow of hydraulic fluid through the piston when the piston encounters the end caps of the cylindrical tube.
In some applications it is desirable to provide a hydraulic cylinder that slows down as the piston approaches the end caps. Such hydraulic cylinders are known as cushion hydraulic cylinders. Typically cushion hydraulic cylinders restrict the flow of exhaust fluid as the piston approaches the ends of its stroke thereby slowing the movement of the piston. One cushioning system uses multiple longitudinally arranged hydraulic metering orifices formed in the wall of the cylindrical tube for increasingly restricting the flow of exhaust fluid out of the hydraulic cylinder as the piston moves toward the end of its stroke. In other embodiments, the piston itself has been provided with longitudinally arranged hydraulic metering orifices. In addition, the top of the pistons themselves maybe provided with cap assemblies that restrict the flow of exhaust fluid out of the hydraulic cylinder.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a cushion hydraulic cylinder that better controls the acceleration and/or deacceleration of the piston.
It is a feature of the present cushion hydraulic cylinder that the cylinder and the piston both have flow control orifices for controlling the flow of hydraulic fluid to and from the cylinder.
A cushion hydraulic cylinder is provided with at least one longitudinally separated metering orifice in the wall of the cylinder through which the flow of fluid is regulated. As the piston extends towards these metering orifices, a circumferential seal sequentially covers and uncovers the metering orifices further regulating the flow of fluid. In addition, the piston is provided with radial bores, having longitudinal passages which are in fluid communication with either the piston side of the cylinder or the rod side of the cylinder. The first longitudinal passage is provided with a passage orifice through which fluid can flow after a circumferential piston seal unblocks a covered metering orifice. The second longitudinal passage is provided with a check valve which prevents the flow of exhausted fluid and only allows for the flow of pressurized fluid. In the illustrated embodiment, the passage orifice is smaller than any of the metering orifices however this is not necessary for the proper functioning of the invention.
It should also be noted that the illustrated embodiment has three metering orifices in the wall of the hydraulic cylinder. However, a single large orifice maybe used provided its diameter is greater than the width of the sealing rings on the piston.
REFERENCES:
patent: 3229589 (1966-01-01), Langas
patent: 3592106 (1971-07-01), Baughman
patent: 4089251 (1978-05-01), Louviot
patent: 4151784 (1979-05-01), Fussangel
patent: 4424737 (1984-01-01), Endo
patent: 4425836 (1984-01-01), Pickrell
patent: 4651623 (1987-03-01), Rogers
patent: 4706781 (1987-11-01), Ikimi et al.
patent: 4767255 (1988-08-01), Mickelson et al.
patent: 4825752 (1989-05-01), Kiffmeyer
patent: 4862786 (1989-09-01), Boyer et al.
patent: 5018934 (1991-05-01), Steinkamp et al.
patent: 59490 (1949-09-01), None
patent: 227034 (1966-04-01), None
Deere & Company
Ryznic John E.
LandOfFree
Cushion hydraulic cylinder does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Cushion hydraulic cylinder, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cushion hydraulic cylinder will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2584231