Motors: expansible chamber type – Three or more cylinders arranged in parallel radial or... – Cylinders parallel to rotation axis
Reexamination Certificate
1999-02-19
2001-08-28
Lopez, F. Daniel (Department: 3745)
Motors: expansible chamber type
Three or more cylinders arranged in parallel radial or...
Cylinders parallel to rotation axis
C092S057000
Reexamination Certificate
active
06279452
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an axial piston machine of the pivoting carriage type of construction, with an internal bearing-flushing system.
2. Discussion of the Prior Art
The starting point of the invention is an axial piston machine, such as is known, for example, from DE 42 15 869 C1. This published specification discloses an axial piston machine of the pivoting carriage type of construction. The known axial piston machine comprises a pivotable cylinder drum and a drive shaft mounted in a drive shaft bearing arrangement. The drive shaft is connected to a drive shaft flange in which pistons movable in cylinder bores in the cylinder drum are articulated and on which the cylinder drum is supported via a central journal. There is also provided, between the cylinder drum and a closing plate on the end face, a lens-shaped control mirror body which has control nodules for the cyclical connection of the cylinder bores to the working lines. A positioning arrangement, which is not represented in detail in DE 42 15 869 C1, is provided for tilting the cylinder drum, together with the control mirror body. In order to supply the drive shaft bearing arrangement with flushing agent, a flushing duct is provided in the central journal and in the drive shaft. The leakage oil draining out of the drive shaft bearing arrangement as a result of the flushing of the bearings is conveyed away in the direction of an opening in the housing by a vane wheel provided on the drive shaft flange.
From DE 36 38 890 C2, it is known practice to provide an axial piston machine of the oblique-axis type of construction having a constant, non-adjustable displacement volume, with a flushing agent duct which extends through the central journal and the drive shaft. The flushing agent is removed, by means of a valve needle which is displaceable in a pressure-dependent manner, from that control nodule of the control part which conducts low pressure.
However, this design solution cannot be used in axial piston machines of the pivoting carriage type of construction with a cylinder drum which is tiltable for the purpose of varying the displacement volume, without problems arising which cannot be overcome in practice. In particular, it has turned out that malfunctions of the valve needle occur if the control mirror body also impacts the stop means which determine the minimum and maximum displacement volumes in each case. The valve needle jams as a result of impact loads which arise in the process, and cracks can occur in the control mirror body In addition, the solution with an integrated valve needle which is known from DE 36 38 890 C2 has likewise proved unsuccessful because the bores and recesses necessary for receiving the flushing needle lead to a weakening of the control mirror body and the feeding pressure protection for the flushing agent is not constant because of the rotation and the pivoting movement of the cylinder drum and of the control mirror body. A further disadvantage is that the feeding pressure setting for the flushing agent cannot be set from outside, since the feeding pressure valve is not accessible from outside and the flushing valve integrated into the control mirror body depends upon the nominal size, since the distance between the control nodules is different for each nominal size of the axial piston machines. It has also turned out that the quantity of flushing agent introduced into the flushing duct by the flushing valve integrated into the control mirror body is inadequate for some applications.
For the reasons mentioned above, the solution known from DE 36 38 890 C2 for axial piston machines with a constant displacement volume has not proved successful in practice in the case of axial piston machines of the pivoting carriage type of construction with variable displacement volume.
SUMMARY OF THE INVENTION
The underlying object of the invention, therefore, is to make available a suitable flushing agent supply system for an axial piston machine of the pivoting carriage type of construction.
Underlying the invention is the knowledge that the flushing agent duct for supplying the drive shaft bearing arrangement with flushing agent and, optionally, for additionally flushing the housing, can be routed, in a simple manner, through the positioning journal and the control mirror body as far as the central journal. The flushing and feeding pressure valve can then be disposed out side the control mirror body, a fact which substantially simplifies the design of the latter, so that the mechanical strength of the said control mirror body is not weakened by the measures necessary for constructing the flushing duct. In addition, the advantage arises that a flushing and feeding pressure valve which can be provided externally can be set from the outside and the quantity of flushing agent introduced into the flushing agent duct can be adapted to the actual demand in a simple manner.
According to the invention, the central bore in the control mirror body for receiving the positioning journal may, at the same time, be part of the flushing agent duct, so that no design changes are necessary at the control mirror body for constructing the flushing agent duct. According to another aspect, there may be constructed in the positioning journal a bore which forms the flushing agent duct in this region and opens into the central bore in the control mirror body. Under these circumstances, the only modification to the positioning journal which is necessary for the flushing agent duct is the construction of the said bore. The bore may be constructed with a diameter which is so small that the mechanical strength of the positioning journal is insignificantly weakened by this measure, in particular by less than 1%.
According to a further aspect, the positioning arrangement may have a hydraulically actuatable positioning piston in which a transverse bore is constructed in order to receive the positioning journal. According to a still further aspect, the positioning piston may be guided in a longitudinal bore which is constructed in a closing plate and is provided with a longitudinal groove into which the bore in the positioning journal opens, either directly or else indirectly via the transverse bore in the positioning piston. Under these circumstances, the longitudinal groove guarantees a supply of flushing agent in any position of the positioning piston and of the positioning journal inserted in the latter. Under these circumstances, connection of the bore in the positioning journal to the longitudinal groove provided in the closing plate is ensured, irrespective of the pivoting position of the cylinder drum, of the control mirror body and of the positioning journal inserted in the positioning piston. According to a specific feature, the longitudinal groove may be connected to an in-feed line for the flushing agent. The flushing and feeding pressure valve for introducing the flushing agent into the flushing agent duct may be mounted externally on the closing plate at the orifice of the in-feed line. Under these circumstances, the flushing and feeding pressure valve is particularly easily settable and accessible from outside.
According to another feature, the flushing agent duct according to the invention may, as well as serving to supply the drive shaft bearing arrangement with flushing agent, at the same time also serve to flush the housing. This results in a particularly favourable heat balance for the axial piston machine, since the heat due to energy losses from the axial piston machine is conducted away, together with the flushing agent, by the agent itself.
REFERENCES:
patent: 4382399 (1983-05-01), Lotter
patent: 4617853 (1986-10-01), Wagenseil et al.
patent: 5545013 (1996-08-01), Beck et al.
patent: 26 25 730 A1 (1977-12-01), None
patent: 31 34 537 A1 (1983-03-01), None
patent: 31 25 264 C2 (1989-07-01), None
patent: 36 38 890 C2 (1990-08-01), None
patent: 42 15 869 C1 (1993-09-01), None
patent: 0 728 945 A1 (1996-08-01), None
patent: 2 207 658 (1973-08-01), None
Brueninghaus Hydromatik GmbH
Lopez F. Daniel
Scully Scott Murphy & Presser
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