Power plants – Pressure fluid source and motor – Having distinct cooling or lubricating structure
Patent
1984-02-29
1987-03-24
Look, Edward K.
Power plants
Pressure fluid source and motor
Having distinct cooling or lubricating structure
92144, F16D 3102
Patent
active
046515267
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a hydrostatic drive, specially for mixing drums of ready-mixed concrete vehicles. German laid-open application No. 29 31 969 has disclosed solutions for simplifying and compacting the constructional assembly of hydrostatic drives by incorporating a hydromotor into the transmission or by using the same as a cooling surface and as common oil conservator, thereby reducing the cooling expenses. However, the structure of the transmission casing shown in said publication, which has a stabilizing space situated before the hydromotor and an uncontrolled oil movement preferably controlled as "spirally rotating collecting current", still does not suffice to meet the requirements of reducing expense and compaction. In order actually to obtain a satisfactory cooling effect even with intensive use and high outside temperatures, there must be provided in this arrangement either larger dimensions for the transmission or higher ventilating effects than are desirable in many cases. To intensify the oil movement by still stronger splashings in the mechanical gear portion likewise cannot be considered.
The problem to be solved by the invention stated in claim 1 is to provide a hydrostatic drive, which requires low energy and serves the purpose with a very small cooling surface without increasing the splashing losses in the mechanical gear portion and which can be economically combined in a compact structure with added mechanical transmission stages.
Said problem is solved by the features indicated in the characteristic part of claim 1. It is thereby obtained that the oil movement in the cooling area be no longer uncontrolled and that a stabilizing space be no longer needed to avoid effects of the splashing in the mechanical gear portion. The oil movement now takes place only in an annular space designed in the manner of a heat exchanger that at the same time makes use only of the area of the transmission casing radially surrounding the hydromotor and completely oil-flooded, that is, it makes unncessary any spacing in front of the hydromotor to a partition that hitherto provided the stabilizing space. It is further obtained that the forced flow through the annular space depends directly on the operation of the pumps and that strong flow changes cannot occur in the remaining front space due to changing direction of the currents and differences of charge. In addition it is obtained that the oil to be cooled cannot accumulate in the corners of a stabilizing space, but must instead completely and substantially simultaneously pass the cooling area, the changing amounts of working oil from the hydromotor becoming always entirely mixed with the amount of flushing oil that is directed past the hydromotor. It is moreover obtained that as consequence of the complete filling of the annular space the zones of the transmission situated higher in the annular space be also oil-wetted in the same manner and, unlike in the known stabilizing space with incomplete filling, the upper area be possibly less immersed in oil or that there locally predominate only slight oil flow and thus poorer heat transfers.
Advantageous embodiments of the invention are described in the sub-claims.
According to one embodiment the front end of the annular space that now extends only over the length of the hydromotor can be at the same time an end to a gear space where entirely different oil currents can be present.
According to another embodiment the splashing effects of the hydromotor can be kept off by the forced flow in the annular space, there being possible high, uniform oil speeds in the area of the outer wall, and yet, depending on the amount and direction, adequate oil can flow off the hydromotor.
According to another embodiment the oil repeatedly has to accomplish its path through the annular space at high speeds, and that many exchange surfaces at high differential temperatures can be available to the heat exchanger.
According to another embodiment free flow of residue can be possible through each one of the annular-space chamber
REFERENCES:
patent: 2476041 (1949-07-01), Happe et al.
patent: 3026814 (1962-03-01), Binhack
patent: 3744377 (1973-07-01), Lauck
patent: 4362390 (1982-12-01), Fischer
patent: 4461147 (1984-07-01), Myers
Sundstrand, Hydro-Transmission Application Manual, 11/79, p. 28.
Bach Hans-Peter
Mann Egon
Look Edward K.
Zahnradfabrik Friedrichshafen AG
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