Motors: expansible chamber type – Working member position responsive motive fluid control – Alternate control of inlet and exhaust for same chamber at...
Patent
1998-09-03
2000-10-10
Lopez, F. Daniel
Motors: expansible chamber type
Working member position responsive motive fluid control
Alternate control of inlet and exhaust for same chamber at...
91399, 91400, 91404, F15B 1522
Patent
active
061290017
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method and an apparatus for controlling the function of a reciprocatable fluid actuated power machine. By fluid actuated power machine is meant, in this connection, all kinds of reciprocatable machines which are actuated by means of compressed air, hydraulic oil or any other fluid, irrespective if said machines are of rotatably or axially operating type, and which can execute its power in two opposite directions, or the machine executes its power in one direction only followed by a return movement without power execution, and whereby the reversing of direction is made by reversing the direction of the compressed air or the hydraulic fluid in the active part of the machine. So, the invention is useful both for single acting and double acting reciprocatable fluid actuated power machines.
In the following the invention will mainly be discussed in connection to pneumatically operated cylinder-piston units. It is, however, to be understood that this is only illustrative examples which do not restrict the invention. Be it known that the invention is as well useful both for linearly operated machines as for rotating machines and for machines operated by compressed air, hydraulic oil or any other fluid.
There are three basic problems of known reciprocatable pneumatic and hydraulic machines both of the single acting and of the double acting type, which problems form basis of the present invention. Said problems appear to the same extent both in rotary operating machines as in axially operating, reciprocatable machines, generally referred to as "compressed air cylinders" or "hydraulic cylinders", but for the sake of simplicity, as mentioned above, the invention will be described in the following only with reference to a pneumatic piston/cylinder unit of reciprocatable type.
All three different main problems, which appear in reciprocatable, pneumatic power machines, are related to the reversing phase, during which phase the active part of the machine, in the described case the compressed air piston, is to reverse its direction of operation. This is made in that the compressed air is switched from having acted on one side of the piston to acting against the opposite side of the piston.
When reversing the direction of function in previously known apparatus the compressed air is evacuated from the side of the piston which is the active side until the moment of reversal in that the pressurised working chamber is evacuated at the same time as compressed air is supplied to the opposite side of the piston: the unloading phase create an air blow which is received as an oftenly very high sound or bang, which can be very disturbing; chamber which has so far been pressurised, some amount of compressed air gets lost; such loss of compressed air means an economical loss of value considering the costs and the work for producing said compressed air; evacuated and the opposite compressed air chamber is pressurised by means of the oftenly high air pressure, the piston is immediately or momentarily stopped and momentarily thereafter starts moving in the opposite direction with high speed and high power. This may in some cases cause problems. Said problem also appears in hydraulically operated machines.
Still another problem in pneumatic power machines is to have the active part thereof, generally the piston, stop in a predetermined position. A main reason for this problem is the compressibility of the air.
In single acting reciprocatable cylinders the power stroke is made by means of compressed air, whereas the return movement is generally accomplished by means of return spring. In order to overbridge the power of the return spring it is necessary to make use of a substantially stronger power of the compressed air or the hydraulic fluid than would have been needed if the cylinder had no return spring.
The object of the invention therefore is to eliminate all of the above mentioned problems and disadvantages by suggesting a simple method and a simple type of valve arrangement, and thereby to suggest a
REFERENCES:
patent: 3653299 (1972-04-01), Howard
patent: 4104899 (1978-08-01), Pinkstaff
patent: 4581893 (1986-04-01), Lindbom
patent: 4608910 (1986-09-01), Levenez et al.
patent: 4763560 (1988-08-01), Sasaki
patent: 4932311 (1990-06-01), Mibu et al.
Lopez F. Daniel
Pos-Line AB
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