Pumps – Successive stages – Reciprocating rigid stages
Patent
1997-10-27
1999-03-23
Thorpe, Timothy S.
Pumps
Successive stages
Reciprocating rigid stages
417258, F04B 300
Patent
active
058850619
DESCRIPTION:
BRIEF SUMMARY
The subject invention concerns a pump for compression of air, comprising an inner stationary cylinder in which a piston, arranged for reciprocating movement in said cylinder, divides the cylinder space into two chambers, and a second cylinder, arranged for reciprocating movement about the stationary cylinder, defining a third chamber the volyme of which is several times larger than the total volume of the two first-mentioned chambers.
Manually operated pumps intended to create an excess air pressure inside a closed space are available in a great variety of different designs. Small-size pumps, such as bicycle pumps, are advantageous on account of their manageability and because the force needed for each individual pumping stroke need not be particularly strong. On the other hand, a large number of pumping strokes is needed in order to e.g. build up the required excess pressure inside a bicycle tire from the atmospheric pressure. Larger-size pumps, having ground support, while capable of transferring a larger air volume upon each pumping stroke do, however, require heavier effort on the part of the operator who therefore tires more quickly when working with this type of pump and consequently is prone to gradually pump slower and slower.
On the other hand, pumps of the kind defined above are entirely insufficient when it is desired to create high excess pressures. One example where such high excess pressures are needed is in air guns, which comprise an air container to which in accordance with prior-art technology a pressure cylinder is connected which transfers pressurized air to said container at a pressure of generally up to 200 bars. This compressed-air cylinder may be of the same type as those being part of divers' equipment.
When a pressure cylinder of this kind is used successively to build up a high excess pressure in the compressed-air container of an air gun the pressure inside the cylinder will, of course, drop, soon to reach such a low level that it becomes necessary to replenish the cylinder in order to allow it to be again used to build up the required pressure in the air gun. The replenishment of the cylinder with air to a high excess pressure level must, however, be performed in a depot particularly designed for this purpose or in a factory, where pressure testing must also be done. The marksman sees these measures and the time required therefor as complications, with the result that he may instead choose to keep a number of pressure cylinders in hand. This, in turn, involves extra expenditures on the part of the marksman. Also the transportation of the pressure cylinders is a complication to the marksman on account of the general safety regulations.
From SE-C-463 732 is already known a manually operated pump of the kind outlined in the introduction. This pump works in two steps which makes it quick-acting while at the same time only moderate forces are required to create a high excess pressure inside a container.
The invention provides a pump wich is a further development of the above Swedish Patent Specification. The characterizing features of the invention appear from the appended claims.
The invention will be described in closer detail in the following with reference to the accompanying drawings, wherein
FIGS. 1 and 2 are longitudinal sectional views through the pump in accordance with the invention, showing two different pump positions, and
FIGS. 3 and 4 are longitudinal sectional views through the lower portion of the pump in accordance with a modified embodiment thereof, and illustrate the pump in two different positions.
In accordance with prior-art technology, the pump comprises a first inner cylinder 1 which forms an elongate stationary pump housing, and a second cylinder 2 which is displaceable for reciprocating motion externally of the first cylinder and which forms a movable pump housing.
Inside the stationary cylinder 1 a piston 3 is attached to one of the ends of a piston rod 4, the latter projecting through an end wall 5 of the stationary cylinder 1, and the opposite end of the
Axelsson Fredrik
Olofsson Sigfrid
CNC--Process I Hoava AB
Moses Daniel E.
Thorpe Timothy S.
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