Motors: expansible chamber type – Relatively movable working members with one having motive...
Patent
1985-03-22
1987-12-29
Jones, Larry
Motors: expansible chamber type
Relatively movable working members with one having motive...
91243, 60416, F01B 100, F16D 3102
Patent
active
047152656
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process as set forth in the classifying portion of claim 1 and an apparatus as set forth in the classifying portion of claim 3.
Pulse-hydraulic processes and apparatuses of that kind are used in particular for operating the working tools in earth moving equipment such as for example total output-controlled excavators, skimmers, loaders and the like. Due to the vibratory movement of the tools, they can dig relatively easily into kinds of ground which are difficult to deal with. Particularly when dealing with chemically compacted or consolidated sands and shingles, hard coal and brown coal, coral, chalk, bedded limestone and in heterogeneous or weathered hard rocks, it is possible to use smaller working machines than was hitherto usual, as the degree of operating efficiency thereof is substantially enhanced by virtue of the pulse hydraulic arrangement.
DE-A No. 22 36 381 ; discloses a grab-type or loading shovel of an earth moving appliance, which at its forward edge has movably mounted teeth to which hydraulic actuating means are connected. The hydraulic actuating means are operated in a vibratory mode. In that arrangement, the teeth perform a shears-like movement. That shovel is suited primarily for operating in loamy or clayey grounds.
DE-C No. 19 57 469 discloses a pulse hydraulic means which can be used for vibratory operation of a working piston. That arrangement comprises a piston which is acted upon on both sides, in a cylinder. The two cylinder chambers in front of and behind the piston are connected to a control device which in its interior has a constantly rotating control slider which in a constantly changing sequence connects on the one hand the return conduit and on the other hand the feed conduit to the hydraulic cylinder, thereby causing a vibratory movement of the piston in the cylinder. The pulse frequency is altered in that arrangement by a change in the speed of rotation of the rotating control piston in the control device. By virtue of axial movement of the control piston, the pressure fluid can additionally be fed to the cylinder in different amounts, thereby making it possible to produce a vibratory sliding movement of the piston.
Finally, AT-A No. 368 607 discloses a similar apparatus wherein the piston is acted upon, only on one side. The piston is slidable in the cylinder against the force of a spring which, when the control device is in the appropriate position, produces a respective return movement of the piston. There is only a single conduit for the feed and discharge of the pressure fluid, between the control device and the hydraulic cylinder. Once again, that arrangement has a control device in the form of a rotary control piston which is also axially slidable for the purposes of controlling the amount of pressure fluid used.
The known processes and apparatuses suffer from various disadvantages. Thus for example in the known pulse-hydraulic cylinders, there is no continuous interchange in respect of the pressure fluid. On the contrary, it is always more or less the same pressure fluid that is moved with a reciprocating pulsating movement in the operating chambers of the cylinders. Because of the rapid increase in temperature, that has a disadvantageous effect on the resistance to aging of the pressure fluid and the sealing elements.
Another disadvantage of known apparatuses is that high pressure peaks occur at the moment at which the return flow of pressure fluid is closed off by the control device. Such pressure peaks may under some circumstances amount to a multiple of the fed pressure and may result in damage to the hydraulic system or possibly also the operating tool.
Finally, tests have shown that, particularly in regard to excavator buckets, it is difficult to apply a longitudinal movement to each individual tooth, without excessive technical expenditure. A problem is also raised by the vibratory forces which may be transmitted to the entire excavator by way of the bucket arm.
Therefore, a problem of the present invention is to provide a proces
REFERENCES:
patent: 2426409 (1947-08-01), O'Farrell
patent: 2699756 (1955-01-01), Miller
patent: 3145488 (1964-08-01), French
patent: 3592107 (1971-07-01), Ahlenius
patent: 4240326 (1980-12-01), Carle
patent: 4590763 (1986-05-01), Augoyard et al.
Graul Achim
Niedermeier Elmar
Graul Achim
Hinds William R.
Jones Larry
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