Motor-pump assembly

Abstract

The invention relates to a motor-pump assembly having an electric motor, which has a rotor and a stator, and having a pump, which pumps a liquid or a gas or a different pump medium. The pump is in driven connection with the rotor of the electric motor. The electric motor and the pump are enclosed in a common housing. The housing has a casing, on the one end face of which is arranged a motor-end cover and on the other end face of which is arranged a pump-end cover. A non-rotating bearing axis is provided, fixed to the housing, which is borne exclusively by the motor-end cover of the housing and is mounted on the rotor of the electric motor. The pump is arranged adjacent to the electric motor such that the pump and the electric motor are aligned with each other.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. §119(a) of German Patent Application No. 10 2005 050 737.9, filed Oct. 22, 2005, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a motor-pump assembly.

2. Description of Related Art

Such pump assemblies and similar pump assemblies are known from countless documents. See, for example, EP 0 611 887 A1 or WO 01/73295. In these assemblies, an electric motor and a hydrostatic pump are enclosed in a single housing. The pump liquid flows through the motor to cool it.

DE 197 28 802 A1 describes a motor-pump assembly provided with a fixed bearing axis that is borne by a motor-end cover of a housing.

DE 295 19 941 describes a motor-pump assembly having an electric motor, comprising a rotor and a stator, and, in addition, a pump that pumps a liquid or a gas. The pump is in driven connection with the rotor of the electric motor. The electric motor and the pump are enclosed by a common housing. The housing comprises a casing as well as two face-end covers. Viewed in the direction of the axis, the pump is arranged adjacent to the electric motor such that the two are aligned with each other.

Assemblies of this type of design have the great advantage that they are quiet and have a short structural length. However, there is a serious drawback: The diameter of such assemblies is relatively large.

BRIEF SUMMARY OF THE INVENTION

The invention is based on the problem of designing a motor-pump assembly in such a way that the outer diameter is smaller than in the known assemblies and that the noise produced is also small.

The inventor has recognized the following:

In the known motor-pump assemblies, as described in EP 040 187 90, for example, the position of the rotor of the electric motor is influenced by the hydrostatic pump. This can have the result that the air gap between the rotor and the stator of the electric motor is formed eccentrically. This leads to excessive radial forces.

According to the invention, the electric motor and the pump are not arranged radially in each other, but rather axially adjacent to each other, so that the axes of the two are aligned with each other. A non-rotating bearing axis is also essential in accordance with the invention, and this axis is borne by the motor-end cover of the housing and is mounted on the motor of the electric motor.

In such a constellation, the bearing of the rotor of the electric motor, on the one hand, and the bearing of the rotor of the pump, on the other hand, are uncoupled from each other. In no way does the shaft on which the rotor of the pump rests influence the position of the rotor of the electric motor. This leads to a quiet running. Measurements have demonstrated a favorable noise behavior.

Although the arrangement of the electric motor and the pump radially adjacent to each other results in an increase in the axial length of the structure, the outer diameter of the housing is thereby reduced. Indeed, this is what is often important in practice.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The invention as well the prior art are described in greater detail below on the basis of the drawing. Depicted in it, in detail, is the following:

FIG. 1 shows a motor-pump assembly according to the invention in an axial section.

FIG. 2 shows a motor-pump assembly according to DE 100 15 139 A1, likewise in an axial section.

The motor-pump assembly shown in FIG. 1 comprises an electric motor 1 having a rotor 1.1 and a stator 1.2. The stator has stator plates 1.2.1 and a winding 1.2.2. The rotor 1.1 is pot-shaped and, in the axial section shown here, it is U-shaped.

Provided axially adjacent to the electric motor 1 is a hydrostatic pump 2. The axes of the electric motor 1 and the hydrostatic pump 2 are aligned with each other.

The rotor 1.1 of the electric motor 1 is mounted on a bearing axis 3. The bearing axis 3 is resistant to rotation and rigid; that is, it does not turn. Here, a sliding bearing 3.1 is provided between the bearing axis 3 and the rotor 1.1 of the electric motor 1.

The electric motor 1 and the hydrostatic pump 2 are arranged inside of a housing 4. The housing 4 has a cylindrical casing 4.1 and, in addition, a motor-end cover 4.2 and a pump-end cover 4.3. The bearing axis 3 is fixed to the motor-end cover 4.2 by shrinkage fitting. Other fastening possibilities are also conceivable.

The rotor 1.1 of the electric motor 1 is in driven connection with the shaft 2.1 of the hydrostatic pump 2, namely, via a driver plate 1.3, which is joined to the rotor 1.1 of the electric motor 1 in a rotationally resistant manner.

The left end of the shaft 2.1 of the hydrostatic pump can also be mounted on the opposite-lying face of the fixed bearing axis. The bearing can be of any kind, for example, a sliding bearing or a roller bearing. Thus, the bearing axis 3 could have an open-edged, pot-like recess in its end region, in which engages the left end, shown in the figure, of the shaft 2.1 of the pump 2.

The housing 4 has an inlet for medium 5 as well as a medium outlet 6.

The arrows indicate the flow of the medium. This medium is generally an oil. However, it can also be any other medium and thus, for example, a different liquid.

FIG. 2 shows a motor-pump assembly according to the prior art. It comprises an electric motor 1 having a rotor 1.1 and a stator 1.2. The stator 1.2 has stator plates 1.2.1 and a winding 1.2.2. The rotor 1.1 has a pot shape and is U-shaped as viewed in the axial section.

Arranged radially inside of the rotor 1.1 and of the stator 1.2 is a pump 2. As is seen, this pump 2 is completely enclosed by the rotor 1.1 or the stator 1.2, respectively, of the electric motor 1.

In order to create a driven connection between the rotor 1.1 and the pump shaft 2.1, the arm 1.1.1 of the rotor 1 has a bore with inner teeth, which mesh with the outer teeth of the pump shaft 2.1. The pump shaft 2.1 has a pinion gear 2.2, which meshes with an internal geared wheel 2.3, which is arranged eccentrically to the pinion gear 2.2 inside of the rotor 1.1 of the electric motor 1. Arranged axially on both sides of the internal geared wheel 2.3 are side plates 2.4 and 2.5 of the pump 2, in which the pump shaft 2.1 is mounted on sliding bearings 2.4.1 and 2.5.1 so as to rotate.

Provided for supplying the pump medium is a pump medium inlet 5 in an end face of the housing 4. Provided for discharging the pump medium is a pump medium outlet 6 in the same end face of the housing.

The medium drawn into the inlet 5 flows through the electric motor 1 and thereby cools it. It then enters axially or radially into the hydrostatic pump 2, flows through it, and is carried from the outlet 6 to a consuming device.

The noise behavior of the pump is extremely favorable. In operation, it is substantially quieter than known pumps.

The use of the rigid bearing axis 3 allows a reduction in the outer diameter of the assembly by approximately 20%. Moreover, it is possible, on account of the dimensions that thereby result, to use a standard rotor with a standard rotor winding as the rotor 1.1, which leads to cost savings.

LIST OF REFERENCE NUMBERS

• 1 electric motor
• 1.1 rotor
• 1.1.1 arm of the rotor
• 1.2 stator
• 1.2.1 stator plates
• 1.2.2 winding
• 2 pump
• 2.1 pump shaft
• 2.2 pinion gear
• 2.3 internal geared wheel
• 2.4 side plate
• 2.4.1 sliding bearing
• 2.5 side plate
• 2.5.1 sliding bearing
• 3 bearing axis
• 3.1 sliding bearing
• 4 housing
• 4.1 housing casing
• 4.2 motor-end cover
• 4.3 pump-end cover
• 5 medium inlet
• 6 medium outlet

Claims

1. A motor pump assembly, comprising:

an electric motor having a rotor and a stator;

a pump for pumping a medium, said pump being in driven connection with said rotor, said pump being arranged adjacent to said electric motor so that said pump and said electric motor are aligned with each other; and

a common housing enclosing said electric motor and said pump, said common housing having a casing, said common housing comprising: a first end face and a second end face; a motor-end cover being arranged on said first end face; and a pump-end cover being arranged on said second end face; and

a non-rotating bearing axis borne exclusively by said motor-end cover and mounted on said rotor.

2. The motor pump assembly of claim 1, wherein said medium is selected from the group consisting of a liquid or a gas.

3. The motor pump assembly of claim 1, wherein said rotor is mounted by a plurality of sliding bearings on said non-rotating bearing axis.

4. The motor pump assembly of claim 3, wherein said plurality of sliding bearings are formed from said non-rotating bearing axis.

5. The motor pump assembly of claim 1, further comprising:

a driver plate being arranged in a rotationally resistant manner on said rotor; and

a shaft of said pump, said shaft being in driven connection with said driver plate.

6. The motor pump assembly of claim 5, wherein said shaft has a first end that is mounted at an opposite-lying end of said non-rotating bearing axis so that said non-rotating bearing axis is resistant to rotation or so that said non-rotating bearing axis is supported against said shaft.

7. The motor pump assembly of claim 1, wherein said motor-end cover has an inlet for said medium, and wherein said pump-end cover has an outlet for said medium.