Power plants – Pressure fluid source and motor – Cyclically operable reciprocating or oscillating motor or...
Patent
1989-09-07
1991-12-17
Look, Edward K.
Power plants
Pressure fluid source and motor
Cyclically operable reciprocating or oscillating motor or...
60376, 60456, 60464, 60468, 60494, 91437, F16D 3102, F15B 1108
Patent
active
050725840
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The invention relates to a pressure medium-operated driving device.
Driving devices of this type are used for example in hydraulic rams, which serve for driving concrete piles, sheet-pile walls and the like into the ground. The hydraulic working cylinders serving for lifting a hammer are in practice located at a great distance from the hydraulic power source; the length of the connecting lines between the hydraulic power source and working cylinders may amount to 20 to 70 or 100 meters. With such long connecting lines, the volume of the line is greater than that of the working chambers of the cylinder. This means that with an alternate supply of pressure to the two working chambers of the cylinder, the hydraulic working fluid is displaced in an oscillating manner in connecting lines, but never reaches the sump. Thus, the same partial volumes of the working fluid are always heated in the working cylinder, which in the case of long term operation has a disadvantageous influence on the degree of efficiency of the working cylinder and the useful life of the working fluid.
In WO-A1-82/01226, a pressure medium-operated driving device is described, in which working fluid can be removed by way of a non-return valve arrangement from the working lines extending betwen a working cylinder and a reversing valve and can be returned by way of a cooler to the sump. In this way, undesirably intensive heating of the working fluid is prevented. However, in this known solution, altogether one has four lines, which must be guided into the vicinity of the working cylinder. With long lengths of line, this means a considerable expenditure. Also, the controllable valve arrangement of this known driving device as a whole is complicated.
U.S. Pat. No. 4,059,042 discloses a hydraulic brake system for use under arctic conditions, in which an additional line is guided to the brake cylinder, which in the inoperative position of the specially constructed brake valve flushes the brake line with brake fluid. However, in this case there is no double acting working cylinder and likewise an additional line is not required.
U.S. Pat. No. 2,929,212 discloses a double-acting working cylinder, in which the piston is seated on the center of a continuous piston rod. This piston rod has a scavenging channel, which is permanently connected by way of non-return valves to the working chambers of the cylinder. Connected to the working lines by way of non-return valves is a circulating pump, which sucks the hydraulic oil discharged by way of the hollow piston rod, through an auxiliary line and delivers it by way of a cooler to a line, which is connected by the said non-return valves to the working lines. This type of solution again requires a relatively large number of additional lines; also, it is not possible to use a standard working cylinder, since the piston and piston rod must be modified in a specific way.
A pressure medium-operated driving device according should be developed by the present invention so that even with overall long connecting lines between the working cylinder and the pressure pump or the sump for the working fluid, the volume thereof is comparable with the volume of a working chamber of a cylinder, or greater than the latter, cooling of the working fluid being obtained with an overall simple construction of the pipe system and valve arrangement.
This object is achieved according to the invention by a driving device as described hereinafter.
In a driving device according to one embodiment, one has a controllable bypass line connecting the ends of the working lines nearest the cylinder and by opening this working line, one can force the entire volume of working fluid present in the working lines, through the cooling device and replace it by new working fluid sucked in from the pressure medium sump. Since such an exchange of heated working fluid for cooled working fluid needs to be carried out solely at greater time intervals and since the forcing-through of the working fluid takes place without appreciable resistance a
REFERENCES:
patent: 2688313 (1954-09-01), Bauer
patent: 3593519 (1971-07-01), Fuhrimann
patent: 3699847 (1972-10-01), Little
patent: 4059042 (1977-11-01), Bridwell et al.
patent: 4779418 (1988-10-01), Artzberger
Kehrberger Achim L.
Mauch Magnus
Look Edward K.
Philpitt Fred
Ryznic John
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