DE102016103902B4 - Rotor arrangement for a pump and pump unit - Google Patents

Abstract

The present invention initially relates to a rotor arrangement for a pump (01); for example for a gear ring machine in a pump unit. The rotor arrangement according to the invention comprises a rotor (09) for conveying a medium. The rotor (19) has an opening (18) with which it sits in a rotationally fixed manner on a drive shaft (08). According to the invention, the rotor (09) can be tilted about any axis perpendicular to the drive shaft (08) at an axial position of the drive shaft (08) relative to the drive shaft (08). Furthermore, the invention relates to a pump unit, which comprises the rotor arrangement according to the invention.

Description

The present invention initially relates to a rotor arrangement for a pump, for example for a gear ring machine in a pump unit. Furthermore, the invention relates to a pump unit, which comprises the rotor arrangement according to the invention.

Pumps are known from the prior art in which a gear pump is designed to convey a medium. Gear pumps of this type are designed, for example, as a gear ring machine which is also referred to as a gerotor. An inner toothed ring forms a rotor of the pump, on which, due to the pressure generated, a transverse force acts, which has to be counteracted by an appropriate bearing. If this transverse force cannot be compensated for sufficiently, the rotor will be displaced, which can have a negative effect on the running properties in particular.

The JP 2012-026294 A shows a fluid pump with a gear ring machine, the inner ring of which is mounted on a drive shaft and on an axle journal formed on a housing.

The JP 2015-048784 A teaches an electric oil pump with a gear ring machine. A drive shaft of the oil pump is mounted in a housing at an axial end of the drive shaft.

From the DE 10 2012 204 191 A1 an electric oil pump is known in which a housing has a bearing section for mounting a pointed end section of a shaft in order to additionally support the shaft.

The EP 1 580 431 A1 , the JP 2015-108306 A and the EP 2 570 672 A2 show gear pumps in which an outer ring gear is supported by a plain bearing.

The DE 35 00 799 A1 , the DE 10 2004 028 127 A1 , the DE 10 2011 000 533 A and the DE 10 2013 223 999 A1 also describe an underlying prior art from the gear pump category

Finally, they reveal WO 2015/019 859 A1 , the US 2014/0 178 234 A1 and especially the DE 10 2011 011 384 A1 Details of rotor arrangements on which the invention is based as the closest prior art.

Starting from the prior art, the object of the present invention is to minimize the undesirable influence of a transverse force on the rotor of a pump.

The stated object is achieved by a rotor arrangement according to the attached claim 1 and by a pump unit according to the attached independent claim 7.

The rotor arrangement according to the invention is intended for a pump for conveying a medium. The pump preferably forms a pump unit together with an electric motor. The rotor arrangement comprises a rotor, which by rotation serves to directly convey the medium and thus forms a pump rotor. The design of the rotor must be selected according to the principle of the pump used. If the pump is formed, for example, by a gear pump, the rotor is a gear or a toothed ring. The medium is preferably a liquid, particularly preferably an oil.

The rotor has an opening with which it sits in a rotationally fixed manner on a drive shaft, so that rotation of the drive shaft leads to rotation of the rotor. Torque can thus be transmitted from the drive shaft to the rotor. The drive shaft protrudes at least into the opening or preferably through it. The opening forms an axis of rotation of the rotor. The opening represents a hub of the rotor and is preferably continuous. The drive shaft forms a component of the rotor arrangement.

According to the invention, the rotor can be tilted in an operating state at an axial position of the drive shaft with respect to the drive shaft about any axis perpendicular to the drive shaft, i. H. tiltable. Said axis of tiltability intersects the drive shaft in said axial position of the drive shaft. Said axis of tiltability has an arbitrary angle of rotation with respect to the drive shaft, so that the tiltability of the rotor is independent of the angle of rotation of the drive shaft. The operating state is a state in which the rotor is completely mounted on the drive shaft, so that the rotor is seated on the drive shaft in a rotationally fixed manner and the rotor arrangement can be used for its function in the pump.

Since the rotor can be tilted about each axis perpendicular to the drive shaft yielding the transverse force at the said axial position, the rotor can follow an occurring transverse force without tilting relative to the axis of rotation. The drive shaft yielding the lateral force is then no longer exactly in the axis of rotation. However, since the rotor can be tilted in relation to the drive shaft in the axis of rotation its function in the pump is not restricted. In particular, it does not occur that the rotor rotates with increased friction compared to other stationary or rotating components of the pump in the event of a tilt with respect to the axis of rotation. Rather, the rotor shifts parallel to its main plane of extension.

A particular advantage of the rotor arrangement according to the invention is that a bearing of the drive shaft and the rotor on both sides of the rotor is not necessary due to the fact that the tiltability can be ensured with little effort. All that is required is a bearing on one side of the rotor, since according to the invention the rotor is able to tilt relative to the drive shaft yielding the transverse force.

The tiltability of the rotor relative to the drive shaft is limited, so that the rotor can be tilted up to a maximum tilt angle relative to the drive shaft. The maximum tilt angle is preferably so large that a maximum deflection of the drive shaft that occurs during operation of the rotor arrangement can be compensated for, so that the rotor does not tilt relative to the axis of rotation. The maximum tilt angle is preferably at most 5 ° and particularly preferably at most 1 °. The maximum tilt angle is preferably at least 0.1 ° and more preferably at least 0.5 °.

The opening has a first axial section, which also forms a first axial section of the drive shaft. In this first axial section, a gap is formed around the drive shaft in the opening of the rotor between the rotor and the drive shaft, which gap represents a play in the radial direction between the rotor and the drive shaft. The circumferential gap is increasingly formed in the axial direction. Thus, the size of the gap extending in the radial direction, i. H. the gap width in the axial direction. This gap, which increases in the axial direction, allows the rotor according to the invention to be tilted relative to the drive shaft, without the play between the rotor and the drive shaft being unnecessarily large.

The radial direction mentioned is related to the axis of rotation; d. H. that the radial direction is perpendicular to the axis of rotation, namely in the direction of the radii starting from the axis of rotation. The axial direction mentioned is the direction of the axis of rotation.

The opening further has a second axial section, which also forms a second axial section of the drive shaft. In the second axial section, the opening has a non-circular cross-section to which the drive shaft has a corresponding cross-section, so that the rotor in the second axial section sits positively on the drive shaft and a torque can be transmitted from the drive shaft to the rotor. The cross section lies in a plane that is perpendicular to the drive shaft or perpendicular to the opening. The non-circular cross section of the opening or the corresponding cross section of the drive shaft is preferably formed by a polygon or by a single or multiple flat. The polygon is preferably formed by a square. The multiple flat is preferably formed by a double. Between the non-circular cross section of the opening and the corresponding cross section of the drive shaft, there is preferably a play in the radial direction, which is preferably between 0.05 mm and 0.5 mm.

The first axial section is divided into a first axial section and a second axial section. The size of the circumferential gap extending in the radial direction, i. H. the gap width is constant in the axial direction in each of the two axial sections, but it differs between the two axial sections so that the circumferential gap is increasingly formed in the axial direction. A step of the gap is thus formed between the two axial sections. The stepped gap can be given by the fact that the opening in the rotor has different diameters in the two axial subsections and / or that the drive shaft has different diameters in the two axial subsections.

The circumferential gap has a smaller size extending in the radial direction in the second axial section, i. H. a smaller gap width than in the first axial section. The play in the radial direction between the drive shaft and the rotor is thus the smallest in the second axial section. In particular, the play in the radial direction between the drive shaft and the rotor in the second axial section is preferably minimal.

The first axial section preferably comprises at least half of the axial length of the opening and can also comprise the entire axial length of the opening.

In preferred embodiments of the rotor arrangement according to the invention, the drive shaft has a convex longitudinal section in an axial region carrying the rotor, in particular in the first axial section. The longitudinal section lies in a plane in which the axis of rotation also lies. The convexity is formed in relation to the shaft bearing surface in the opening of the rotor and allows the rotor to tilt relative to the drive shaft.

In preferred embodiments of the rotor arrangement according to the invention, the rotor has a convex longitudinal section in the region of its opening, in particular in the first axial section of its opening. The longitudinal section lies in a plane in which the axis of rotation also lies. The convexity is formed in relation to the drive shaft and allows the rotor to be tilted in relation to the drive shaft.

The drive shaft preferably also has an axial motor section in which the drive shaft forms a component of an electric motor for driving the pump; in particular a motor shaft of a motor rotor. The axial motor section is axially spaced from the first axial section and the second axial section. The axial motor section is axially spaced from the rotor of the pump and its opening. Torque is generated in the electric motor and transmitted to the drive shaft. The torque is further transmitted from the drive shaft to the pump rotor.

The first axial section of the drive shaft is preferably arranged axially between the second axial section and the axial motor section. The second axial section of the drive shaft is preferably formed on one of the two axial ends of the drive shaft. The drive shaft preferably protrudes completely into the opening of the rotor with its axial end. It can protrude through the opening of the rotor with an axial play.

In the first axial section, the opening and the drive shaft each preferably have a circular cross section. The cross section lies in a plane that is perpendicular to the drive shaft or perpendicular to the opening.

The circumferential gap preferably has the shape of a hollow cylinder in each of the two axial sections.

The opening in the rotor preferably has the shape of a cylinder in the first axial section. Insofar as the opening in the two axial sections has different diameters, the opening in the two axial sections preferably each has the shape of a cylinder.

The drive shaft preferably has the shape of a cylinder in the first axial section. Insofar as the drive shaft has different diameters in the two axial sections, the drive shaft in the two axial sections preferably has the shape of a cylinder.

The second axial section is preferably arranged between the first axial section and the second axial section. As a result, the second axial section is located in a central axial region of the opening. The second axial section is preferably located in an axial center of the opening.

The circumferential gap has a size extending in the radial direction in the second axial section, i. H. a gap width, which is preferably between a thousandth and a hundredth of the diameter of the drive shaft in the second axial section. The circumferential gap has a size extending in the radial direction in the second axial section, i. H. a gap width which is preferably between 0.01 mm and 0.07 mm, particularly preferably between 0.03 mm and 0.05 mm.

The circumferential gap in the first axial section has a size extending in the radial direction, i. H. a gap width, which is preferably between a hundredth and a tenth of the diameter of the drive shaft in the first axial section. The circumferential gap has a size extending in the radial direction in the second axial section, i. H. a gap width which is preferably between 0.08 mm and 0.3 mm, particularly preferably between 0.1 mm and 0.2 mm.

The first axial section preferably has an axial length that is between one tenth and five tenths of the axial length of the opening. This axial length is particularly preferably between two tenths and four tenths of the axial length of the opening.

The second axial section preferably has an axial length that is between one tenth and five tenths of the axial length of the opening. This is particularly preferably axial Length between two tenths and four tenths of the axial length of the opening. As an alternative, the second axial section preferably has a technically minimal axial length, so that it forms a peripheral edge against which the drive shaft and the rotor abut with a minimal play in the radial direction. This edge forms the fulcrum for tilting the rotor.

The second axial section preferably has an axial length that is between one tenth and five tenths of the axial length of the opening. This axial length is particularly preferably between two tenths and four tenths of the axial length of the opening.

The opening further preferably has an axial insertion section in which it is widened with respect to the circumferential gap. The opening is preferably widened conically with respect to the circumferential gap. The drive shaft protrudes into the opening of the rotor starting at the insertion section.

The drive shaft preferably has a smaller extent in the radial direction in the second axial section than in the first axial section. The drive shaft in the second axial section preferably has an outer diameter of the non-circular cross-sectional shape that is smaller than the diameter in the first axial section, in particular smaller than the diameter in the second axial section.

The drive shaft preferably has a circumferential phase between the first axial section and the second axial section, which is preferably formed at the transition from the larger extension in the radial direction in the first axial section to the smaller extension in the radial direction in the second axial section. This phase is a circular bevel of the transition described. The phase ensures sufficient tiltability without requiring a larger gap width in the second axial section.

Between the first axial section and the second axial section, a free space extending in the axial direction is preferably formed between the drive shaft and the rotor. This free space leads to play in the axial direction between the drive shaft and the rotor, which prevents striking sideways when the rotor tilts.

In preferred embodiments of the rotor arrangement according to the invention, the drive shaft is formed by a motor shaft of an electric motor. The electric motor is designed to drive the rotor and thus to drive the pump. The motor shaft has the above-mentioned axial motor section and an axial pump section, the axial pump section being seated in the opening of the rotor.

The motor shaft preferably has exactly two axial bearing sections in which it can be rotatably supported; in which it is designed in particular for inclusion in a plain bearing or in a roller bearing. One of the exactly two bearing sections is arranged on an axial end of the motor shaft opposite the pump section, so that it is located in the axial motor section. The other of the exactly two bearing sections is arranged between the axial motor section and the axial pump section.

In any case, there is preferably no bearing section at that axial end of the drive shaft which is located in the axial pump section, i. H. the drive shaft is not designed for rotary mounting there. It is namely a particular advantage of the rotor arrangement according to the invention that a rotary mounting of the drive shaft at this axial end can be dispensed with, since the drive shaft can bend slightly under load without the rotor being tilted relative to the axis of rotation.

The rotor is designed in accordance with the working principle of the pump, which can be any working principle with rotating components. The pump is preferably a gear pump, in particular a gear ring machine, which is also referred to as a gerotor. The rotor is thus preferably formed by a gear wheel, in particular by an inner tooth ring.

The rotor, in particular the inner toothed ring, is designed to have an axial play in the pump of preferably less than 0.1 mm, particularly preferably less than 0.02 mm.

The pump is preferably a pump for conveying an operating fluid in a motor vehicle; for example an oil pump.

The pump unit according to the invention serves to convey a medium. The pump unit comprises a pump designed in an axial pump section of the pump unit for the direct delivery of a medium. The pump unit further comprises an electric motor designed to drive the pump in an axial motor section of the pump unit. The pump unit comprises the rotor arrangement according to the invention. The drive shaft of the rotor arrangement forms a motor shaft of the electric motor and is non-rotatably connected to the rotor arranged in the pump. The electric motor preferably has a motor rotor comprising the motor shaft and a motor stator. The rotor of the pump is preferably formed by an inner ring, the pump preferably further comprising an outer ring, the inner ring and the outer ring forming a gear ring machine.

The pump unit preferably comprises one of the preferred embodiments of the rotor arrangement according to the invention. Otherwise points the pump unit also prefers those features which are specified in connection with the rotor arrangement according to the invention and its preferred embodiments.

The pump unit is preferably an electric oil pump for a motor vehicle.

• 1: eine seitliche Ansicht einer Ausführungsform eines erfindungsgemäßen Pumpenaggregates;
• 2: das in 1 gezeigte Pumpenaggregat in einer Längsschnittansicht;
• 3: eine erfindungsgemäße Rotoranordnung des in 1 gezeigten Pumpenaggregates; und
• 4: das in 1 gezeigte Pumpenaggregat in einer perspektivischen Detailansicht.

Further advantages, details and developments of the invention result from the following description of an embodiment of the invention, with reference to the drawing. Show it:

• 1 : a side view of an embodiment of a pump unit according to the invention;
• 2nd : this in 1 shown pump unit in a longitudinal sectional view;
• 3rd : an inventive rotor arrangement of the in 1 pump unit shown; and
• 4th : this in 1 shown pump unit in a perspective detailed view.

1 shows a side view of an embodiment of a pump unit according to the invention, which is designed to convey oil in a motor vehicle. The pump set includes a pump 01 and an electric motor 02 to drive the pump 01 . The pump 01 includes an inlet 03 and an outlet 04 for the oil to be pumped.

2nd shows that in 1 shown pump unit in a longitudinal sectional view. The electric motor 02 includes a motor stator 06 and a motor rotor 07 . The motor rotor 07 includes a motor shaft 08 which is simultaneously a drive shaft of the pump 01 forms. The pump 01 includes an inner ring 09 and an outer ring 11 which form a gear ring machine. The inner ring 09 sits rotatably on the drive shaft 08 and forms a rotor of the pump 01 .

The drive shaft 08 is at exactly two axial positions, each with a roller bearing 12 stored in rotation; namely on both sides of the motor rotor 07 , so that one of the two bearings 12 axially between the motor rotor 07 and the inner ring 09 is arranged. Hence the drive shaft 08 only on one of the two sides of the inner ring 09 stored so one in the pump 01 arranged axial end 13 the drive shaft 08 is not stored.

Using the pump 01 a pressure of between 3 bar and 25 bar on the oil to be pumped can be generated. Due to the principle of action of the inner ring 09 and the outer ring 11 The gear ring machine formed acts via the inner ring 09 a shear force on the drive shaft 08 from the direction of the inlet 03 . Because the drive shaft 08 at its axial end 13 is not stored, the drive shaft bends 08 in the area of the axial end 13 so that the drive shaft 08 in this area opposite an axis of rotation 14 is tilted. This tilt does not mean that the inner ring 09 opposite to the axis of rotation 14 is tilted because, according to the invention, the inner ring 09 opposite the drive shaft 08 is tiltable. This tiltability is independent of the angle of rotation of the drive shaft 08 given so that the inner ring 09 at any angle of rotation of the drive shaft 08 opposite the drive shaft 08 is tiltable. This tiltability is due to a special design of the drive shaft 08 in her the inner ring 09 supporting axial area. This axial area initially comprises a first axial section 16 and a second axial section 17th . The second axial section 17th is used to transmit torque from the drive shaft 08 on the inner ring 09 what the drive shaft for 08 in the second axial section 17th has a square cross section, which has a radial play of a few tenths of a millimeter in the inner ring 09 sits. A the drive shaft 08 receiving opening 18th in the inner ring 09 points in the second axial section 17th a square cross-section, so that a non-rotatable connection between the drive shaft 08 and the inner ring 09 is trained.

The first axial section 16 is in a first axial section 19th and in a first axial section 21st divided. Throughout the first axial section 16 point the drive shaft 08 and the opening 18th each have a circular cross-section. Throughout the first axial section 16 is between the drive shaft 08 and the inner ring 09 in the opening 18th a circumferential gap 22 (shown in 3rd ) is present, so that there is play in the radial direction between the drive shaft 08 and the inner ring 09 given is. However, the circumferential gap 22 in the first axial section 19th about 0.15 mm and in the second axial section 21st only about 0.04 mm wide. Hence the gap 22 in the first axial section 19th in the radial direction larger than in the second axial section 21st . The circumferential gap 22 can also be used as a free cut in the drive shaft 08 to be discribed.

The drive shaft 08 and the one rotor of the pump 01 performing inner ring 09 form a rotor arrangement according to the invention, which by the tiltability of the rotor 09 opposite drive shaft 08 regardless of the angle of rotation of the drive shaft 08 is marked.

3rd shows that from the drive shaft 08 and the inner ring representing a rotor 09 formed rotor assembly of the in 1 and 2nd Pump unit shown in detail. In the second axial section 21st is the circumferential gap 22 only about 0.04 mm wide. Hence the circumferential gap 22 very small, so the play in the radial direction between the drive shaft 08 and the inner ring 09 in the second axial section 21st is very small. The second axial section 21st forms the fulcrum for the tilting of the inner ring 09 opposite the drive shaft 08 . The second axial section 21st has an axial length a, which is about a third of an axial length b of the opening 18th is.

On the electric motor 02 (shown in 2nd ) facing side has the opening 18th a conical extension 24th in the form of a phase. The drive shaft 08 points at that end of the first axial section 16 , which corresponds to the second axial section 17th is facing a phase 26 which also contributes to the tiltability. Between the first axial section 16 and the second axial section 17th is between the drive shaft 08 and the inner ring 09 a free space extending in the axial direction 27 present so that between the drive shaft 08 and the inner ring 09 there is also play in the axial direction, which also contributes to the tiltability.

4th shows that in 1 and 2nd Pump unit shown in a perspective detail view, in which the pump 01 is shown in an open state. It is especially the one through the inner ring 09 and the outer ring 11 formed gear ring machine and the drive shaft 08 recognizable. The drive shaft 08 points in the second axial section 17th (shown in 3rd ) has a square cross-section.

Reference symbol list

01

pump

02

Electric motor

03

inlet

04

Outlet

05

-

06

Motor stator

07

Motor rotor

08

Motor shaft / drive shaft

09

Inner ring / rotor of the pump

10th

-

11

Outer ring

12

roller bearing

13

axial end

14

Axis of rotation

15

-

16

first axial section

17th

second axial section

18th

opening

19th

first axial section

20th

-

21st

second axial section

22

circumferential gap

23

-

24th

conical extension

25th

-

26

phase

27th

free space

Claims (7)

Rotor arrangement for a pump (01), comprising a rotor (09) for conveying a medium, which has an opening (18) with which it sits on a drive shaft (08), the rotor (09) being fixed to the drive shaft (08 ) is attached; wherein the rotor (09) at an axial position of the drive shaft (08) relative to the drive shaft (08) can be tilted about any axis perpendicular to the drive shaft (08); wherein the opening (18) has a first axial section (16), in which a circumferential gap (22) is formed between the rotor (09) and the drive shaft (08) and has a gap width that extends in the radial direction, which axial direction is increasingly formed; and wherein the opening (18) further has a second axial section (17), in which it has a non-circular cross section, to which the drive shaft (08) has a corresponding cross section, so that the rotor (09) in the second axial section (17) of the opening (18) sits positively on the drive shaft (08), characterized in that the first axial section (16) is divided into a first axial section (19) and a second axial section (21), the gap (22 ) in the two axial sections (19, 21) is always constant in the axial direction, and the gap (22) in the second axial section (21) has a smaller gap width than in the first axial section (19). Rotor arrangement after Claim 1 , characterized in that the rotor (09) has a convex longitudinal section in the region of its opening (18) and / or the drive shaft (08) in an axial region carrying the rotor (09). Rotor arrangement after Claim 1 or 2nd , characterized in that the circumferential gap (22) has a gap width between 0.08 mm and 0.3 mm in the first axial section (19) and a gap width between 0.01 mm and 0.07 mm in the second axial section (21). Rotor arrangement according to one of the Claims 1 to 3rd , characterized in that the opening (18) further has an axial insertion section (24) in which it is widened in a cone shape with respect to the circumferential gap (22), the drive shaft (08) starting in the insertion section (24) into the opening (18 ) of the rotor (09) protrudes. Rotor arrangement according to one of the Claims 1 to 4th , characterized in that the drive shaft (08) further comprises an axial motor section in which the drive shaft (08) forms a component of an electric motor (02) for driving the pump (01). Rotor arrangement according to one of the Claims 1 to 5 , characterized in that the rotor is formed by an inner ring (09) of a gear ring machine (09, 11). Pump unit for conveying a medium, comprising a pump (01) formed in an axial pump section, an electric motor (02) formed in an axial motor section and a rotor arrangement according to one of the Claims 1 to 6 , The drive shaft (08) forms a motor shaft of the electric motor (02) and is connected in a rotationally fixed manner to the rotor (09) arranged in the pump (01).

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