Power plants – Pressure fluid source and motor – With control means for structure storing work driving energy
Patent
1998-09-04
2000-06-13
Lopez, F. Daniel
Power plants
Pressure fluid source and motor
With control means for structure storing work driving energy
60416, 60417, 91395, 91420, F16D 3102
Patent
active
060734418
DESCRIPTION:
BRIEF SUMMARY
The present invention generally relates to a piston-cylinder unit of single acting type, whereby is means a piston-cylinder unit which performs an operative (working) stroke in one direction (working direction) and which is returned to its initial position by a minimum of force.
A previously suggested type of such "pneumatic cylinder" is formed so that the pressure side of the piston receives compressed air of high pressure along the entire working stroke, whereas the unloading (inactive) side of the piston receives very little pressure over the greatest part of the working stroke, but so that said unloading side of the piston is supplied with the same pressure as that of the pressure side a slight distance from the end of the working stroke. When the pressure at the working side of the piston is thereafter drained there is a pressure remained at the unloading side of the piston, and said pressure is used for returning the piston to its initial position for the working stroke, whereby the pressure side of the cylinder is drained, so that the piston can be returned only by means of the power from the return-compressed air. This way of operating a pneumatic cylinder involves a great saving of compressed air. An example of said previously suggested type of pneumatic "saving cylinder" is shown in the Swedish patent No 9401187-1 (corresponding to PCT/SE95/01115).
In some cases it is, however, desired that the piston operates with full pressure over its entire, or at least almost its entire working stroke, and that the unloading side of the cylinder is thereby drained of compressed air during practically the entire working stroke. It is also often desired that the cylinder is formed so that there is a connection means for compressed air only at one end of the cylinder, especially close to the end of the pressure side thereof.
There may appear problems to build up a return-air-pressure in the unloading volume of the cylinder at the same time as the piston is allowed to operate at full pressure over the entire working stroke. It is also important that the apparatus is formed so that the piston does not hit the end of the cylinder with a strong force at the moment of reversing movement, and this happens if the piston rams into the front end of the cylinder with full force.
The invention therefore intends to provide a single acting pneumatic piston-cylinder unit which is designed so that the piston is loaded with full working pressure over the entire working stroke thereof, and so that the unloading space of the cylinder in drained over the entire, or almost the entire working movement of the piston. Return air pressure is created, in a secondary stage of the piston movement, when the entire working stroke has come to an end, in one or more compressed air tanks arranged inside the cylinder. To that end, and to prevent the piston from strongly hitting the front cylinder end, at least during its working stroke, the piston and the cylinder is formed with co-operating means for providing a dampening of the final movement of the piston.
Further, according to the invention the piston of the piston-cylinder apparatus is formed with a valve apparatus for letting a slight amount of air of full pressure into one or more of compressed air tanks of the cylinder at said secondary stage. Said slight amount of compressed air is utilized to return the piston to its initial position of the working stroke. It is important that the valve is kept closed during the entire working stroke of the piston, so that compressed air is transferred to the return chamber thereby reducing the total pressure and the movement of the piston.
Further characteristics and advantages of the invention will be evident from the following detailed specification in which reference will be made to the accompanying drawings, in which
FIG. 1 is an axial cross section view through an embodiment illustrating an example of a piston-cylinder apparatus according to the invention during its working stroke.
FIG. 2 is a transversal cross section through the apparatus of
REFERENCES:
patent: 2703558 (1955-03-01), Wilcox
patent: 3410180 (1968-11-01), Spangler et al.
patent: 3552274 (1971-01-01), Bojan
patent: 3645170 (1972-02-01), Varouxis
patent: 3901130 (1975-08-01), Lange
patent: 4706781 (1987-11-01), Ikimi et al.
Lazo Thomas E.
Lopez F. Daniel
Pos-Line AB
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