1994-11-01
1996-08-27
Freay, Charles
Pumps
Diverse pumps
F04B 2308
Patent
active
055494528
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a double pump consisting of a radial piston pump and a vane-cell pump combined to form a pump unit. A common shaft drives the radial piston pump situated on the input side and the vane-cell pump lying on the end of the shaft. The casing of the radial piston pump encloses a ring insert which contains the delivery piston. A pump set, consisting of a rotor, vanes and a cam ring, seals against face plates abutting on both sides of the pump set. Such double pumps are often used in motor vehicles and are driven by the vehicle engine via a V-belt. Here the radial piston pump preferably provides a level adjustment and the vane-cell pump a servo-assisted steering gear.
BACKGROUND OF THE INVENTION
A double pump of this construction has already been disclosed in DE-OS 41 03 986. For accommodation of the radial piston pump, this design has one casing which at the same time forms a face plate for the pump set of the vane-cell pump. An aperture in the casing includes a ring insert for the delivery piston. A casing lid closes said aperture. Therefore, there are at least two separations for sealing the casing containing both pump systems, namely, the separation on the casing lid and the separation between the face plate of the cup-shaped casing and the pump set of the vane-cell pump. Sealing rings are inserted in both said separations.
SUMMARY OF THE INVENTION
The problem to be solved by the invention is to structurally simplify said double pump so as to obtain a compact and weight-saving design. Besides, one separation of the casing is to be eliminated.
According to the main feature of the invention, the ring insert containing the delivery piston and the face plate for the vane-cell pump which faces the radial piston pump form a common part. By virtue of this feature, the ring insert with the face plate can be introduced into the casing of the radial piston pump together from one side and only one separation to be sealed between the two pumps remains. Besides, contrary to the prior art, the face plate molded on the ring insert is no longer part of the casing, which therefore can be made thinner. Thereby the axial length of the double pump diminishes.
According to the invention, the face plate of the ring insert has a bore for supporting the shaft. Since a special bush bearing can be eliminated, said support is less expensive.
According to the invention the ring insert in addition forms a stop face for the shaft in the area of the eccentric. A special guard ring can also be spared here.
According to the invention, it is of further advantage that only one pin is needed for securing the ring insert, the cam ring and the other face plate lying on the remote side of the radial piston pump against torsion.
According to the invention it is convenient for simpler manufacture of the contour of the frontal side to make the ring insert of sintered steel or A1 die cast metal. Said materials offer good antifriction properties together with slight wear and tear.
BRIEF DESCRIPTION OF THE DRAWINGS
An embodiment of the invention is explained in more detail with reference to the drawing showing a longitudinal section through a double pump. Since the basic structure of both pumps is generally known, it is mainly the parts essential to the invention that will be taken up herebelow.
DESCRIPTION OF THE PREFERRED EMBODIMENT
A radial piston pump 1 and a vane-cell pump 2 are joined by screws 3, spaced on the frontal surface of the casing, to form a unit. The piston pump 1 has a casing 4 with a large aperture 5. A shaft 6 extends through the casing 4 into another casing 7 of the vane-cell pump. A ring insert 8, which contains several cylindrical bores 10 for receiving delivery pistons 11, is fitted in the aperture 5 of the piston pump 1. An eccentric 12 fixed on the shaft 6 sets the delivery pistons 11 in a stroke motion. During the suction stroke, the inlet bores 13 immerse in a suction space 14 so as to fill their interior spaces with oil. During the pressure stroke, a band valve 15, which is coordinated wit
REFERENCES:
patent: 2512025 (1950-06-01), Lauck
Freay Charles
ZF Friedrichshafen AG
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