Pumps – Diverse pumps – Including rotary nonexpansible chamber type
Patent
1998-02-06
2000-02-08
Jeffery, John A.
Pumps
Diverse pumps
Including rotary nonexpansible chamber type
417269, 417238, 417350, 4171991, 417370, 417429, 74 1586, F04B 2314
Patent
active
060221984
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a double pump unit having two hydraulic pumps with drive shafts coaxially arranged and coupled to each other through the intermediary of a coupling piece, in a force-locking manner.
2. Discussion of the Prior Art
Such a double pump unit is known from DE-OS 33 24 583. The known double pump unit has two hydraulic pumps having drive shafts arranged coaxially with one another, which drive shafts are coupled with one another by means of a coupling piece, in a force-locking manner. The coupling piece is thereby constituted in the form of a hollow shaft and is connected with the free drive shaft ends of the two hydraulic pumps by means of a spline/groove toothing. The coupling piece is surrounded by a connection piece which accommodates the suction channels and pressure channels leading to the hydraulic pumps. The double pump unit known from DE-OS 33 24 583 draws the pressure medium to be delivered directly out of a low-pressure line, without previously subjecting the pressure medium to a pre-compression. Thereby, the efficiency of the known double pump unit is limited and additionally there exists a danger of damage due to cavitation in the suction channel.
In order to counter this danger, it is on the other hand known from DE-PS 30 18 711 to connect a charging pump upstream of a hydraulic pump. The charging pump consists of an impeller formed in the manner of a turbine, which rotates in a correspondingly formed chamber.
SUMMARY OF THE INVENTION
Starting from DE-OS 33 24 583, the object of the present invention is to so further develop a hydrostatic double pump unit that a charging pump is integrated in a manner more simple in terms of construction and more cost effective.
Corresponding to the solution in accordance with the invention, there is provided in the connection piece an inlet pressure chamber into which the suction channels open out. The coupling piece has peripherally arranged blade elements which rotate in the inlet pressure chamber and thus feed the pressure medium into the suction channels under an initial pressure.
Thereby, the invention is based on the insight that the coupling piece, which is in any event already present and rotates with the drive shafts, can be employed as impeller for the charging pump when a corresponding inlet pressure chamber is provided in the connection piece and the coupling piece is provided with corresponding blade elements. This solution requires only a slight additional constructional outlay and is therefore particularly economical.
The connection piece may be formed in two parts, consisting of a main body and a lid-like closure part which closes the main body. Thereby, the coupling piece, with its blade elements, can be introduced into the main body of the connection piece through a correspondingly dimensioned opening in the main body, which opening can be closed by means of the closure part. This makes possible a particularly simple assembly and servicing of the coupling piece constituted as an impeller. Thereby, the connection piece can also accommodate the suction channel and pressure channel leading to the neighbouring hydraulic pump.
In a particularly advantageous manner, the coupling piece, including its blade elements, can be formed as a one-piece impeller.
Further, the coupling piece can be manufactured as a hollow shaft and be connected with the free ends of the driving shafts of the hydraulic pumps, by means of a spline/groove toothing.
The suction channels leading to the hydraulic pumps can either, open out into a common suction opening in the inlet pressure chamber and branch off to the two hydraulic pumps above, in the direction of flow, the suction opening, or there may be provided for each suction channel a separate suction channel opening. Correspondingly, the coupling piece can be formed as an impeller solely at one of its ends, by the arrangement of the blade elements, or, it can be formed in impeller shape symmetrically at both ends.
BRIEF DESCRIPTION OF THE DRAWI
REFERENCES:
patent: 2910008 (1959-10-01), Weisenach
patent: 3644067 (1972-02-01), Yowell
patent: 4014628 (1977-03-01), Ruseff et al.
patent: 5183392 (1993-02-01), Hansen
patent: 5800134 (1998-09-01), Hasegawa et al.
Brueninghaus Hydromatik GmbH
Fastovsky Leonid
Jeffery John A.
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