Expansible chamber devices – Rotating cylinder – Plural cylinders
Patent
1996-12-26
1999-12-14
Lopez, F. Daniel
Expansible chamber devices
Rotating cylinder
Plural cylinders
92 71, F01B 302
Patent
active
060003162
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a hydraulic axial piston machine having a cylinder drum with at least one cylinder, in which a piston is arranged to move back and forth, which piston bears by way of a slider shoe against a swash plate, wherein a pressure plate is provided which holds the slider shoe in contact with the swash plate and is supported against the cylinder drum by way of a ball-and-socket joint comprising a ball-like body and a counterpart.
In an axial piston machine of that kind, the pressure plate is guided without axles or shafts, that is to say, the shaft around which the cylinder drum rotates is not taken through the pressure plate. Such an arrangement is frequently used in the case of smaller axial piston machines, although the principle can be applied regardless of the size of the axial piston machine.
Since the pressure plate is intended to hold the slider shoes in contact with the swash plate, it must carry out a continuous tilting movement with respect to the cylinder body on rotary movement of the cylinder drum. To allow this tilting movement, U.S. Pat. No. 2,733,666 provides a ball-and-socket joint which is formed from a ball which is inserted on the one hand in a correspondingly spherical recess in the pressure plate and on the other hand lies in a correspondingly spherical recess in the end face of a piston which is displaceable in the cylinder drum and is supported with respect to the cylinder drum by a pressure spring.
Such an arrangement requires the pressure plate to be provided with a spherical recess, however, which leads to commensurate weakening of the pressure plate with the result that deformation of the pressure plate is to be feared should correspondingly larger forces be applied. This in turn results in the slider shoes no longer being held in face-to-face contact with the swash plate, but lifting slightly, so that the desired hydrostatic lubrication of the slider shoes is no longer guaranteed. In addition, the operational behaviour of the machine changes if the pistons do not completely travel the prescribed distance.
The invention is based on the problem of improving the operational behaviour of an axial piston machine.
In a hydraulic axial piston machine of the kind mentioned in the introduction, this problem is solved in that a pressure plate part of the ball-and-socket joint associated with the pressure plate has a supporting surface which extends substantially parallel to the surface of the pressure plate and by means of which the pressure plate part lies in face-to-face contact with the pressure plate.
This construction of the pressure plate part avoids weakening the pressure plate or keeps any weakening small. The forces acting by way of the pressure plate part on the pressure plate are primarily transmitted through the bearing area. Widening of the recess known from U.S. Pat. No. 2,733,666, for instance in a radial direction by forces acting like wedges, which the ball shown in that specification makes possible, can at least largely be avoided by the new construction. The changed force transmission now enables the slider shoes to be held against the swash plate with greater reliability.
Greater pressure forces can even be applied, which further improves the operational behaviour of the machine, for instance, when it is wished to use the machine as a pump. In that case higher suction pressures are possible.
The pressure plate preferably has a shaped configuration on its upper side with a bounding wall oriented substantially radially. This configuration enables forces also acting in a radial direction to be transmitted to the pressure plate. These forces are not, however, converted by forces resulting from the effect of a slope into axial forces, such as are to be observed, for example, in the case of a spherical recess. On the contrary, a relatively good separation of axial and radial forces acting on the pressure plate is achieved by this construction. In the case of the radially acting forces, the pressure plate now has virtually its entire radius available as abut
REFERENCES:
patent: 3468263 (1969-09-01), Niemiec
patent: 3636820 (1972-01-01), Lambeth
patent: 3807283 (1974-04-01), Alderson et al.
patent: 3978772 (1976-09-01), Miyao et al.
patent: 4117768 (1978-10-01), Affouard
patent: 5032061 (1991-07-01), Porel
M.o slashed.ller Henry Madsen
Martensen Lars
Danfoss A/S
Lopez F. Daniel
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