Axial piston machine with internal flushing circuit

Details Axial piston machine with internal flushing circuit Axial piston machine with internal flushing circuit

1998-08-11

2000-06-20

Yuen, Henry C.

Pumps

Three or more cylinders arranged in parallel, radial, or...

417201, 92 72, F04B 112

Patent

active

060770503

DESCRIPTION:

BRIEF SUMMARY
The invention relates to an axial piston machine, preferably of swash plate construction, with a revolving cylinder drum arranged on the drive shaft and working pistons supported via slippers on a swash plate the tilt angle of which may, if appropriate, be adjustable, with which machine the housing inner chamber of the pump housing, filled with leakage operating medium, is bounded by a roller bearing by means of which the drive shaft is mounted in the pump housing, and there is arranged outside the roller bearing a shaft sealing arrangement, and in which there is provided a device for the conveying of operating medium through the bearing gap of the roller bearing.
With axial piston machines of this kind, for critical applications, which are for example operation of the machine at high temperatures, operation with operating media containing water and particular demands on the operating time and reliability, there is needed an external bearing flushing, by way of an external connection. Such an external flushing serves, apart from bearing lubrication, simultaneously to cool the shaft sealing arrangement, for lubrication and to avoid possible deposits on the sealing lip. Such an external cooling and lubrication is complex, since in particular adaptation to the operating state of the pump is necessary in each case.
In U.S. Pat. No. 2,825,499 there is described a cooling compressor in the form of an axial piston pump of the kind mentioned in the introduction. There, between the roller bearing for the drive shaft and the shaft sealing arrangement, sealing off the drive shaft with regard to the housing from the exterior, a toothed wheel pump. This toothed wheel pump sucks operating medium out of the housing inner chamber and conveys it to the shaft sealing arrangement for cooling and lubrication. In order to return the operating medium into the housing inner chamber there is provided a channel which returns the operating medium from the space before the shaft seal through the bearing gap of the roller bearing into the housing inner chamber. Thus, an internal flushing circuit is provided which, however, has the disadvantage that a separate small, complete pump device, consisting of rotor and stator, is provided. This is complex in terms of construction and has the further disadvantage that in the region of the axial piston pump in which, according to experience, the greatest build up of heat occurs there is arranged a further machinery unit between roller bearing and shaft seal which takes up construction space. Finally, by means of the additional flushing pump device the operating medium is transported directly against the shaft sealing arrangement, so that there is needed a very fine tuning in the setting up of the conveying capacity of the flushing pump device, in order to have a desired flushing and cooling for all ranges of speed of rotation of the axial piston pump.
The object of the invention is to provide an internal forced flushing circuit in an axial piston machine of the kind mentioned, for which no additional constructional space is necessary and which is effective non-critically for all speed of rotation operating ranges of the axial piston machine.
To achieve this object, an axial piston machine having the features of the preamble of claim 1 is characterised in that there is provided a conveyor plate revolving with the drive shaft, before the bearing gap of the roller bearing on the side of the housing inner chamber, which conveyor plate urges the operating medium through the bearing gap in the annular chamber between roller bearing and shaft sealing arrangement, and in that the annular chamber is connected with the housing inner chamber by means of a discharge channel.
This configuration ensures a flushing medium quantity which is dependent upon the speed of rotation, both for the roller bearing and also for the shaft sealing arrangement, i.e. a larger quantity of operating medium is conveyed at higher speeds of rotation and correspondingly occurring greater heat generation. Also, the quantity conve

REFERENCES:
patent: 4005948 (1977-02-01), Hiraga et al.
patent: 4413954 (1983-11-01), Okazaki
patent: 5411385 (1995-05-01), Eto et al.
patent: 5971717 (1999-10-01), Berthold

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