Rotary piston machine

A rotary piston machine includes a driving part driven by an electric motor, and a driven part that have mutually engaging end-face denticulation for delivering a medium, the driving part and the driven part being housed in a machine housing and connected to the machine housing via respective bottom bearings of the driving/driven parts, creating a unit.

BACKGROUND OF THE INVENTION

The invention proceeds from a rotary piston machine having end-face denticulation in a driving part and in a driven part and having, disposed between the denticulation, working spaces that increase and decrease in size during the rotation producing the delivery action of the medium, is described in the (older) patent application 10 2004 044 297 A1, which was not pre-published.

The underlying object of the invention is to improve the rotary piston machine such that it can be produced in a particularly favorable manner without sacrificing the advantages described in the available, older application.

SUMMARY OF THE INVENTION

The rotary piston machine according to the invention has special advantages compared to the aforementioned rotary piston machine. Because of the fact that the driving part and the driven part are arranged within the machine housing and are enclosed by the bottom bearing, it is possible to adjust the clearance retroactively, down to a basic setting, and it is also possible to suppress a subsequent clamping of the running parts, because there is a unit between the bottom bearing and machine housing. Thus, a required axial clearance is retained.

In accordance with one advantageous embodiment of the invention, for fixing it in the machine housing, the radial edge area of the bottom bearing can be screwed or glued or pressed into a corresponding end-face opening in the machine housing, so that the bottom bearing can be attached to the machine housing in very different manners. What is critical is that a unit is attained.

For favorable running of the rotors, in accordance with one embodiment of the invention the driving part and/or the driven part has a journal on the side facing away from the pump space, and the bottom bearing has an annular central bearing bore for receiving the journal. According to additional embodiments of the invention, the machine housing embodied as a unit can be admitted into a pump housing that can be closed on the end-face facing away from the electric motor, whereby the pump housing can be embodied in the shape of a pot with a bottom that runs on an incline to a center axis for supporting the bottom bearing of the driven part.

In accordance with the invention, the space in front of at least one of the driving/driven parts on the side facing away from the pump working space can be connected hydraulically to the pressure side of the pump working space, so that the rotors can be loaded in opposition to one another, whereby bores or channels in the machine housing can provide the hydraulic connection.

Another embodiment of the invention, a clearance-equalizing catch coupling that is arranged between the shaft end of the electric motor and the driving part, whereby the catch coupling is embodied as an annular/plug-in part having a profiled interior recess for engaging the shaft end of the electric motor and also having an insertion journal for engaging in corresponding openings on the side of the driving part that faces away from the pump space. Such clearance-equalizing catch couplings are known per se, but are novel for a rotary piston machine of the type claimed. Above all, motor conditions are now decoupled from the pump and, vice versa, pump singularities are decoupled from the motor, by means of this clearance-equalizing catch coupling. Decoupling the drive is significant especially by creating a unit between pump parts and machine housing.

Additional advantages and advantageous embodiments of the invention can be taken from the following description, drawings, and the claims.

The drawings depict one exemplary embodiment of the subject of the invention and it is described in greater detail in the following.

DETAILED DESCRIPTION OF THE INVENTION

The depicted fuel delivery pump has a rotary piston pump1and an electric motor2that drives the rotary piston pump1, and these are arranged in a motor housing3and a housing cover4attached thereto. This is a highly simplified depiction of the electric motor with a rotor5, a magnet ring6, and an axial locking part7of the motor housing3that is connected and sealed thereto. In addition, a pivot bearing8of the rotor5is provided on this locking part7. The fuel flows around the electric motor5,6inside the motor housing3in order to cool it.

The second rotational bearing of the rotor5is provided at a shaft end9thereof in a bearing bore10of a bottom bearing11that is arranged in a corresponding opening on the end-face of a machine housing12of the rotary piston pump1and on which a driving part13with denticulation on the end-face can be supported. This machine housing12is arranged in a pump housing14that seals the motor housing3and is arranged partially therein and partially within the housing cover4. The shaft end9projects into a bearing bore15that has a large diameter and that runs coaxial with the bearing bore10and in which a journal16, inserted therein, of the driving part13is rotatably borne.

Arranged in the bearing bore15, between the shaft end9of the electric motor2and the journal16of the driving part13is a catch coupling17as is shown enlarged inFIGS. 3 and 4. Since the shaft end9is borne in the bottom bearing11and also the driving part13with its journal16, this catch coupling17should cause a certain clearance equalization, specifically in both the longitudinal and transverse directions. The bottom bearing11is embodied as a fixed bearing and is rigidly arranged between the machine housing12, the pump housing14, and the magnet ring6.

Two pump rotors work in the machine housing12, specifically a driven part18in addition to the driving part13. The driving part13is driven by the shaft end9of the electric motor2and the catch coupling17and transmits its rotational movement to the driven part18through denticulation. Cycloid denticulation is provided on the end-faces of the driving part13and the driven part18and have corresponding working surfaces that face one another. As is shown inFIG. 2, this is how pump working spaces19are formed between these working surfaces and the inner wall of the machine housing12.

As can be seen fromFIGS. 3 and 4, the catch coupling17has an annular part20with a hexagonal interior recess21into which a corresponding hexagonal end section of the shaft end9of the electric motor2is inserted for the desired rotational connection and at the end face of which four insertion journals23are arranged that are inserted into corresponding openings arranged on the end-face of the journal16.

An end-face opening in the machine housing12is closed on the driven side by a bottom bearing22that is arranged coaxially with the driven part18. Arranged in this bottom bearing22is a bearing bore24in which the driven part18is borne via a journal25thereof. As cannot be seen fromFIGS. 1 and 2, in addition the driving part13and the driven part18are loaded in opposition to one another by the hydraulic delivery pressure in which between the pump space on the pressure side and the sides of the driven/driving parts13,18facing away from one another a connection is comprised via bores or channels. The driven part18is supported with a spherical elevation26on a corresponding spherical recess27of the driving part13.

As depicted inFIGS. 1 and 2, in special cases the pump housing14can be embodied in a pot shape, with a bottom28that correspondingly runs on an incline to the drive axis but at a right angle to the axis of the driven part18and on which the bottom bearing22of the driven part18is placed and supported. This advantageously provides an additional constructive decoupling of the pump side from the drive side, which can be of particular significance during servicing. All of the features depicted here can be essential to the invention individually and in any combination with one another.

LEGEND