WO2022122927A1

WO2022122927A1 - Shaft-hub connection and fluid pump comprising the shaft-hub connection

Info

Publication number: WO2022122927A1
Application number: PCT/EP2021/085008
Authority: WO
Inventors: Marcel BERNER; Sebastian EGERMEIER; Robin GEMEINHARDT
Original assignee: Nidec Gpm Gmbh
Priority date: 2020-12-11
Filing date: 2021-12-09
Publication date: 2022-06-16
Also published as: DE102020133212A1

Abstract

The invention relates to a shaft-hub connection for a pump rotor (3a) on a pump shaft (2a), comprising: a shaft (2) having a shaft outer surface (6) and a central axis (M); a hub (3) which has a hub opening (4) comprising a hub inner surface (5) for receiving at least one portion (7) of the shaft (2), wherein the hub opening (4) has a hub axis (N); wherein the shaft (2) has at least one transverse bore (8) for receiving at least one driver element (9) and the hub inner surface (5) has, corresponding to the at least one transverse bore (8), at least one axial groove recess (12) and wherein at least one driver element (9) is accommodated in the at least one transverse bore (8) and projects radially outwardly beyond the shaft outer surface (6) at least in portions. The projecting portion (7) of the driver element (9) sits in the axial groove and the projecting portion (7) of the driver element (9) has a crowned or spherical surface. A sum of the individual diameters of the driver elements (9) is greater than the shaft diameter (Dw) in the axial region of the transverse bore (8).

Description

Shaft-hub connection and fluid pump having the

shaft-hub connection

The invention relates to a shaft-hub connection according to the preamble of claim 1 and a fluid pump having the shaft-hub connection.

A generic shaft-hub connection is known from WO 02/099300 A1. This shaft-hub connection uses convex longitudinal grooves in the shaft and/or in the hub, in which driver elements are seated, which are designed like rollers with convex or at least rounded outer surfaces. Such a shaft-hub connection is expensive to manufacture. 3D form milling work is necessary, which means increased production costs.

With a large number of grooves distributed over the circumference, there is also the risk of static overdetermination, so that the production of the groove geometry and the groove positions relative to one another and with respect to the shaft must be very precise and only narrow shape and position tolerances can be allowed. In addition, design-related static overrides regarding wear and noise, i. H. e.g. B. lead to unnecessary efficiency losses in the operation of a fluid pump.

In particular when used for a fluid pump, static overdeterminations can lead to changing frictional behavior between the shaft and the hub, which—if the hub is a pump rotor, for example—can lead to pulsation in the pressure build-up of the pump.

A generic shaft-hub connection is known from DE 4224736A1.

Against this background, it is an object of the invention to provide a simple manufacturing process, in particular without complex 3D shapes such. B. 3D Provide form milling, manufacturable shaft-hub connection, which on the one hand is able to compensate for an angular offset between a shaft and a hub and on the other hand allows a rigid up to material elasticity torque transmission between the shaft and the hub. The angular offset to be compensated, in particular in the area of the fluid pumps, is in the range of a few degrees, in particular between 0° and 3°, particularly preferably between 0° and 1°.

It is not an explicit object of the invention to provide an articulated connection, as is common, for example, in the field of cardan or constant velocity joints and allows angular offsets of several degrees up to several tens of degrees.

The focus of this invention is a simple producibility of the shaft-hub connection with simple shaping process such. B. drilling, broaching, turning and the like. Such simple, inexpensive and widespread methods should allow such a production. In addition, mechanical overdeterminations and the disadvantages resulting therefrom should at least be reduced.

Furthermore, the object of the invention is to specify a fluid pump which is particularly insensitive to an angular misalignment, in particular between a drive shaft and a rotor of the fluid pump, with deflection or bending of the drive shaft under load caused by forces on the rotor Misalignments between the rotor and the shaft can occur. Such a fluid pump should be able to be insensitive to such angular misalignments with little wear and tear and little noise.

The tasks are solved with a shaft-hub connection with the features of claim 1. Advantageous embodiments are specified in the dependent claims. The tasks with regard to the fluid pump are solved with a fluid pump having the features of claim 19 .

According to the invention, a shaft-hub connection, in particular for a pump rotor on a pump shaft, has: a shaft with a shaft outer surface and a central axis M; a hub with a hub opening having a hub inner surface for accommodating at least a partial area of the shaft, the hub opening having a hub axis N, the shaft having at least one transverse bore for accommodating at least one driver element and the hub inner surface corresponding to the at least one transverse bore having at least one axial groove recess each and wherein at least one driver element is accommodated in the at least one transverse bore, which at least partially protrudes radially outwards beyond the outer surface of the shaft and the protruding subarea of the driver element sits in the axial groove, the protruding subarea of the driver element having a convex or spherical surface. Such a shaft-hub connection is developed according to the invention in that the sum of the individual diameters of the driver elements is greater than the shaft diameter in the axial area of the transverse bore.

With a shaft-hub connection according to the invention, it is possible to achieve an angular offset between a shaft and a hub while maintaining a particularly rigid torque transmission capability, with particularly simple manufacturing methods being able to be used to form the shaft-hub connection. For example, the transverse bore can be produced in a simple manner by means of drilling, the inner surface of the hub, the outer surface of the shaft by turning/internal turning and the axial grooves by means of broaching. The sintering of the hub is further simplified. This is the most economical method for large quantities. The driver elements are designed in a particularly simple manner as rolling bodies, namely as balls.

Such a shaft-hub connection is able to provide angular misalignments of up to a few degrees between a drive shaft and an impeller or, more generally, a hub carrier.

The torque is transmitted in a relatively rigid manner, since the driver elements are subjected to shearing or pressure and in this Load direction are designed to be particularly stiff except for material-specific elasticity.

Such a shaft-hub connection makes it possible to tolerate higher manufacturing tolerances at another point of a piece of equipment in which the shaft-hub connection is used, since an angular misalignment can be accepted.

The structure of the shaft-hub connection also makes it possible to have to comply with a minimum of tight tolerances in the shaft-hub connection itself. For example, only a distance dimension between the contact surfaces of the axial groove and the balls has to be tolerated particularly tightly in order to allow as little rotational play as possible. In an embodiment described further below, this requirement can also be omitted by providing prestressing elements. Furthermore, it only has to be ensured that a central run is possible, i. This means that the shaft sits as centrally as possible in the hub. Such tolerances are few in number and less complex in terms of compliance. In particular, expensive position and surface tolerances, as they occur in statically multiply overdetermined systems according to the prior art, are eliminated. Furthermore, the complex formation of 3D contour surfaces is advantageously dispensed with in the case of the invention.

In addition, facilitated angular movement is enabled through minimal side constraint of the connection. A particularly smooth movement can be expected in particular in the small angular offset range of up to 3°, in particular up to 1°.

In particular when the transverse bore is filled by means of similar spherical driver elements, it is possible with the invention in a simple manner to set a required number and/or size of the balls via their diameter.

If the diameter of the driver elements is selected according to the invention so that a sum of the diameters of the driver elements is greater than that Shaft diameter in the axial area of the transverse bore, it is possible in the simplest case to provide only two driver elements that sit in the transverse bore and still form a radial overhang that can be used in conjunction with the axial groove recess for torque transmission.

With the invention it is thus possible to create a shaft-hub connection that is particularly simple in design and can be realized with a few components that are easy to produce. Such a shaft-hub connection, which can compensate for small angular offsets defined in more detail above, is particularly suitable for use in fluid pumps, especially in small fluid pumps and the manufacturing tolerances that usually occur in this technical field.

A sensible upper limit for the diameter of each driver element, which according to the invention is greater than half the shaft diameter in the area of the transverse bore, is readily apparent to the person skilled in the art depending on the torque to be transmitted, which is caused by the driver elements on the one hand and the remaining wall thickness of the shaft in the area of the transverse bore on the other hand must be transmitted. Of course, this remaining wall thickness cannot be made arbitrarily thin at its thinnest point. For example, a residual wall thickness at the thinnest point of at least 10% to 20%, in particular at least 15% to 20%, of the shaft diameter has proven to be expedient for the area of application of small fluid pumps. With such a construction, for example, in the case of a residual wall thickness of 20%, the radial overhang of each of the driver elements can be 10% of the shaft diameter.

In a special embodiment, the at least one driver element is designed as a ball.

These are particularly simple standard rolling bodies that are available in large numbers and are available at low cost. Furthermore, the assembly of balls is particularly easy, since they do not have to be aligned to insert the balls. In a particular embodiment, the transverse bore is a through transverse bore or a blind transverse bore.

In the case of a through hole, this is particularly easy to produce, since no consideration needs to be given to a specific depth dimension. A blind hole cross bore is useful if, for example, only a spherical driver element is to be accommodated. In this case, the depth of the blind hole must be tolerated accordingly. In addition, blind holes can be realized in a simple manner for a plurality of driver elements (even or odd) distributed over the circumference, without the driver elements having to be arranged opposite one another in a radial direction. Such an opposite arrangement is, however, made possible in a simple manner with the above-mentioned through transverse bore.

In a further preferred embodiment of the invention, a transverse bore axis QA is aligned at right angles or at an oblique angle to the central axis M.

In the simplest case, the through-cross bore or the cross-bore axis QA is aligned at right angles to the central axis M of the shaft. However, it can also be at an oblique angle, so that the driver elements are arranged offset to one another, viewed in an axial direction of the shaft.

In a further preferred embodiment of the invention, a plurality of driver elements touching one another directly or indirectly sits in the transverse bore.

In order to bridge the cross section of the shaft, a plurality of driver elements touching one another directly or indirectly can be arranged in the transverse bore, in particular in the case of a through transverse bore. Such an arrangement makes it possible, simply by providing a suitable number of driver elements, for the driver elements to protrude radially beyond the outer surface of the shaft ensure and to ensure sufficient support of the driver elements in the radial direction.

A further embodiment of the shaft-hub connection according to the invention is characterized in that the inner surface of the hub, with the exception of the axial groove, is cylindrical or part-cylindrical, ie. H. cylindrical shell-shaped surface.

In this case, the inner surface of the hub can be produced in a particularly simple manner as a bore or as an internal turning surface, into which the axial grooves are then introduced by broaching. This is a particularly simple way of manufacturing.

In a further embodiment of the shaft-hub connection according to the invention, an intermediate piece is inserted between two adjacent driver elements.

In particular for larger shaft diameters, it is advisable to use an intermediate piece between driver elements, i.e. in the area of the center of the shaft. This can optionally be cylindrical or disk-shaped or tubular, so that a punctiform or ring-shaped support of the balls is ensured. This reduces the surface pressure of the balls against each other and prevents unwanted flattening during operation. Furthermore, by providing intermediate elements, a transverse bore with a smaller diameter and thus a transmission of higher torques is possible.

In a further embodiment of the present invention, the intermediate piece is elastically prestressed in order to radially outwardly prestress the driver elements.

The intermediate piece can, for example, a deformable material such. B. be a rubber or hard rubber or a spring element to bias the driver elements radially outwards. This ensures particularly smooth running, since there is no play in the direction of rotation/circumferential direction between the driver elements and boundary walls of the axial grooves, particularly when the boundary walls are inclined.

In a further preferred embodiment, side walls of the axial groove are designed to be inclined by an angle α with respect to a radial direction R.

Side walls of the axial groove that are inclined by an angle α relative to a radial direction R help to ensure particularly low-noise operation of the shaft-hub connection, in particular when driver elements rest radially pretensioned against such sloping/inclined walls.

In a further special embodiment, the hub is designed to be radially expanded axially adjacent to the inner surface of the hub and forms an annular gap with the outer surface of the shaft.

In a further preferred embodiment of the invention, the shaft is designed to be radially reduced axially adjacent to the transverse bore and forms an annular gap with an inner surface of the hub.

With the above two embodiments for generating an annular gap, it is particularly advantageous that the inner surface of the hub and in particular also the corresponding axial grooves can be kept short in the axial direction and thus the processing effort with regard to the corresponding tolerances is minimized due to smaller surface areas. In addition, an annular gap represents a simple way of ensuring that the shaft is centered or axially supported relative to the hub, as will be described further below.

According to an advantageous embodiment, a centering ring is seated in the annular gap for centering the hub relative to the shaft.

A centering ring is a particularly simple way of centering the shaft with respect to the hub in the annular gap by supporting the shaft reach hub. The centering ring is preferably formed from a material that is more elastic than the shaft and/or the hub.

In a further special embodiment, a support ring is seated in the annular gap to limit the axial displacement of the shaft relative to the hub.

A support ring, which may be supported on axial shoulder surfaces of the hub and/or the shaft, can ensure that the hub is fixed axially with respect to the shaft and represents a simple way of ensuring that the hub is guided axially with respect to the shaft.

In a further preferred embodiment of the invention, in the region of a radial outer edge of the transverse bore, the transverse bore is deformed radially inward to a smaller diameter than the diameter of the driver element.

Such a deformation of the transverse bore, for example by squeezing or caulking or some other type of mechanical deformation, is a simple way of avoiding an unintentional loss of driver elements in a period before the shaft is installed in the hub. Due to a locally narrowed free diameter of the transverse bore, at least the driver elements are held captive.

A further embodiment of the shaft-hub connection according to the invention is characterized in that the axial extent of the inner surface of the hub is greater than the diameter of the driver element, in particular greater than the diameter of the driver element in a plane tangential to the outer surface of the shaft and perpendicular to the axis of the transverse bore.

This measure represents a way of ensuring sufficient axial free movement of the balls in the axial groove recess when support rings are provided, and thus providing sufficient suitability of the shaft-hub connection for angle compensation. A further advantageous embodiment of the invention is characterized in that a driver surface of the axial groove recess is curved in cross section, in particular curved in the same direction so as to nestle against the convex or spherical surface of the protruding portion of the driver element.

With this measure, it is possible to achieve a particularly low surface pressure due to the snug fit of the driver element or its spherical or convex surface in the protruding sub-area and thus to increase the service life of the shaft-hub connection.

Another aspect of the invention relates to a fluid pump with a drive shaft and a pump rotor, wherein at least one shaft-hub connection according to one of the preceding embodiments, in particular for the shaft-hub connection between a drive shaft and a pump rotor, the shaft-hub connection according to one of the above embodiments is provided.

The application of the shaft-hub connection according to the invention to a fluid pump has particular advantages in that particularly quiet running with minimal wear is possible. In addition, due to a deliberately tolerated angular offset, the efficiency of a fluid pump, for example a centrifugal pump, can be increased since a lower sealing gap height is possible, so that loss flows are minimized. The shaft-hub connection can tolerate a load-related skewing of a deformed shaft without this necessarily resulting in a skewing of the pump rotor, so that in contrast to the prior art, in which such a skewing of the pump rotor can occur, in the invention such a skewing is prevented and therefore such a misalignment does not have to be taken into account in all sealing gaps by the prophylactic provision of larger sealing gaps. A sufficient avoidance of collisions between the rotor and the surrounding components of the pump chamber can be realized with smaller sealing gaps, so that the efficiency is increased. Furthermore, such a fluid pump benefits from a particularly torsionally rigid possibility of transmitting torque from the shaft to the rotor.

The invention is explained below by way of example with reference to the figures. Show it:

FIG. 1: a longitudinal section along a central axis of a shaft of the shaft-hub connection according to the invention in a first embodiment;

Fig. 2: a longitudinal section along the shaft longitudinal axis of an expanded first

Embodiment of the shaft-hub connection according to the invention in a perspective view;

3 shows a cross section through a center plane of driver elements through the first embodiment of the shaft-hub connection according to the invention;

4 shows a cross section through a second embodiment of the shaft-hub connection according to the invention in a central plane of the driver elements;

figs 5a - 5f: each schematic cross-section through further embodiments of the shaft-hub connection according to the invention in a central plane of the driver elements, the embodiments differing in terms of the configuration of the driver elements (5a and 5b - 5f) and by different cross-sectional configurations of

Distinguish axial groove recesses (5b - 5f).

Fig. 6: a fluid pump having the shaft-hub connection according to FIG

Invention in longitudinal section. A first embodiment of the shaft-hub connection 1 according to the invention is shown in Figure 1 in a longitudinal section, Figure 2 in a perspective longitudinal section and Figure 3 in a cross section through a central plane of driver elements 9.

A second embodiment of the invention is shown in FIG. 4, where the same reference numbers refer to the same or comparable elements and the second embodiment will only be described with regard to its differences from the first embodiment.

Further embodiments of the invention are shown in FIGS. 5a to 5f, where the same reference symbols relate to the same or comparable elements and the further embodiments are only described with regard to their differences from the first embodiment. In particular, the driver element-axial groove recess combinations shown as examples in these embodiments can be easily combined with one another and also with the embodiments according to FIGS. 1 to 3 and 4.

The shaft-hub connection 1 according to the invention according to the first embodiment has a shaft 2, which can be a pump shaft 2a in one possible application. The shaft 2 passes through a hub 3, which in a special application of the invention can be a part or a pump rotor(s) 3a. The hub 3 has a hub opening 4 which is delimited by an inner surface 5 of the hub. The inner surface of the hub 5 is not visible in FIG. 1; it is drawn in FIGS. 2, 3 and 4. The inner surface 5 of the hub is assigned a corresponding outer surface 6 of the shaft. An axial partial area 7 of the shaft 2 passes through the hub opening 4 . As shown in the embodiments, the transverse bore axis QA is perpendicular to the central shaft axis M, but can also be arranged at an oblique angle thereto. In the illustrations according to FIG. 1, the center axis M of the shaft coincides with a center axis N of the hub. The aim of the shaft-hub connection 1 according to the invention is to compensate for an angular offset between the central shaft axis M and the hub axis N. Such an angular misalignment can occur in a small angular range, for example due to elastic deformation of the shaft 2 during operation of a fluid pump (not shown).

Such an angular offset may be in a range between 0° and 3°, in particular in an angular range between 0° and 1°.

Driver elements 9 are seated in the transverse bore 8 and are designed according to the invention, for example as rolling bodies, namely as a ball 10 . A diameter D of the transverse bore 8 essentially corresponds to a diameter D of the ball 10, so that it can be moved in a radial direction R in the transverse bore 8 with no or almost no play.

The diameter D of the balls 10 and the transverse bore 8 is chosen such that twice the diameter D is larger than a shaft diameter Dw, so that driver sections 11 of the ball 10 project beyond the outer surface 6 of the shaft at both ends at the end of the transverse bore 8. The hub opening 4 has axial groove recesses 12 corresponding to the driver sections 11 of the balls 10 projecting beyond the outer surface 6 of the shaft, which are delimited in the circumferential direction U by inclined side walls 13 . The sloping side walls 13 are inclined at an angle α to a radial direction R. The size of the angle a to the radial direction R is acute and preferably chosen such that a normal of the side walls 13 through the contact point of the balls 10 and the side walls 13 intersects an inner wall of the transverse bore 8 in its extension.

The axial groove recesses 12 are easily broached using a suitable broaching tool, e.g. B. a broach, produced. The hub inner surface 5 can be produced in a simple manner by internal turning. The transverse bore 8 of the shaft 2 can be produced in a simple manner by drilling. the Driver elements 9 are designed in a particularly simple manner according to the invention as balls 10, which are available prefabricated as purchased parts/standard parts at low cost and in a large number of desired diameters.

The hub opening 4 is enlarged axially adjacent to the hub inner surface 5 and forms an enlarged hub opening 4 a within the hub 3 . The widened hub opening 4a forms an annular gap 14 in a region axially adjoining the hub inner surface 5 together with the shaft outer surface 6. The annular gap 14 is designed to accommodate a centering ring 15 or a support ring 15a, the functions of which are explained below.

In the event that the hub 3 is to be centered with respect to the shaft 2, ie. i.e. that the central axis M and the hub axis N coincide as far as possible, the centering ring 15 can be inserted in a simple manner in the annular gap 14, which defines a radial position of the shaft 2 in relation to the hub 3, provided that between the shaft outer surface 6 and the Hub inner surface 5 a gap, such as a clearance gap, is present.

The support ring 15a acts as a support ring if it can provide axial support for the shaft 2 with respect to the hub 3 as an alternative or in addition to acting as a centering ring 15 .

For this purpose, it makes sense to place the support ring 15a radially on the outside in the enlarged hub opening 4a, e.g. B. by means of a press fit and to be provided with respect to the shaft outer surface 6 with a clearance fit. In such a case, the shaft 2 can be displaced in the axial direction A until the protruding driver sections 11 of the balls 10 in the axial direction A are in contact with an inner edge 20 of the support ring 15a. With this procedure, a certain axial play and, as a result, an angular offset that can be absorbed can be set in a predetermined manner. This axial play of the shaft 2 with respect to the hub 3 can be predetermined by the selection of the axial longitudinal extension of the hub inner surface 5 . Of course, the support ring 15a can also be fixed to the shaft 2 and to the hub 3 by means of a press fit have a radial clearance fit. In this case, the support ring 15a rests axially on a hub web 5a. A second support ring can optionally be placed on the opposite side against the hub web 5a in the same way, so that the shaft is fixed in the axial direction A with respect to the hub 3 without play or preferably with play.

The driver elements 9, d. H. the balls 10 are accommodated by their driver sections 11 in the axial groove recesses 12 and thus form a rotationally positive but axially displaceable assembly in a circumferential direction U (direction of rotation), by means of which torque can be transmitted from the shaft 2 to the hub 3.

If, for example, the shaft 2 bends or deflects slightly due to mechanical stress, the balls 10 can move in the axial grooves by a small amount in the axial direction A and compensate for an angular offset of the central axis M in relation to the hub axis N, without the circumferential direction U existing rotational form closure is abandoned.

To compensate for such an angular misalignment, it is particularly expedient, if a centering ring 15 is provided, which rests without play on both the outer surface of the shaft 6 and on the inner surface of the enlarged hub opening 4a, so that a centering function is fulfilled, so that it is elastic in design so that it Angular offset of the shaft 2 is not directly transmitted to the hub 3.

In a second embodiment according to FIG. 4, an intermediate piece 16 which is arranged between the balls 10 is provided in the transverse bore 8 in addition to the two driver elements 9 which are designed as balls 10 according to the invention. In the simplest conceivable embodiment, the intermediate piece 16 is a disk against which the balls 10 are supported. The provision of this intermediate piece 16 makes it possible, with a given diameter D of the balls 10 and the transverse bore 8, to produce a larger radial overhang of the driver sections 11 and thus a more favorable balance of power in the contact points between the Balls 10 and the side walls 13 to generate. Higher torques can be transmitted with such an arrangement.

In a further embodiment, the intermediate piece 16 is designed as a ring. Such a configuration has the advantage that there is no point contact between the balls 10 and the intermediate piece 16 but rather a line contact (ring-shaped), so that surface pressures between the balls 10 and the intermediate piece 16 can be kept low.

In a further special embodiment of the invention, the intermediate piece 16 is made of an elastic material, in particular as a compression spring, which is selected with regard to its dimensioning and choice of material such that it prestresses the balls 10 radially outwards when the shaft-hub connection 1 is in the assembled state against the side walls 13 presses. In this way, a play-free, prestressed arrangement of the shaft-hub connection 1 according to the invention can be achieved, so that particularly low-noise operation is ensured.

In a preferred embodiment, the transverse bore 8 is caulked or otherwise mechanically deformed at its open ends after the driver elements 9 (balls 10) have been inserted, so that the diameter of the transverse bore 8 narrows. As a result, the driver elements 9 are held captive. This facilitates in particular the assembly of the shaft 2 with the driver elements 9 in the hub 3.

Furthermore, it can be particularly advantageous to choose the axial extension of the hub inner surface 5 larger than the diameter D of the driver elements 9, ie the ball 10, in particular larger than the diameter D of the driver element 9, ie the ball 10 in a tangential plane to the Shaft outer surface 6 and perpendicular to the cross bore axis QA. If this is the case, the driver section 11, which protrudes in a radial direction R beyond the outer surface of the shaft 6, also projects beyond the inner surface of the hub 5 in the axial direction A, so that by suitably placing the support rings 15a or the centering rings 15 in Axial direction A an axial play and / or a maximum possible angular displacement is easily adjustable.

In this embodiment, it is possible to ensure axial mobility of the balls 10 in the axial groove recess 12, even if support rings 15a should rest on both sides of the hub web 5a. There is sufficient clearance for the balls in the event of an angular offset of the central axis M in relation to the hub axis N.

In a further embodiment of the invention according to FIG. 5a, the driver elements 9 are designed as cylindrical pins 30, which sit with a cylinder section 31 in the transverse bore 8 and have a crowned or spherical driver section 11. In this embodiment of the driver elements 9, it is essential that the driver section 11 of the cylindrical pins 30, which protrudes beyond the outer surface 6 of the shaft, is not cylindrical, but rather has a crowned or spherical three-dimensional shape. According to the invention, an outer cylinder surface of the cylindrical pins 30 should not come into contact with the side walls 13 of the axial groove recess 12 . The configuration of the driver elements 9 as cylindrical pins 30 makes it possible to dispense with the intermediate piece 16 and still ensure that driver elements 9 lying opposite one another in the radial direction R in the transverse bore 8 rest against one another, without having to select an excessively large diameter for the transverse bore 8.

In the embodiment according to FIG. 5a, two cylindrical pins 30 with a crowned and/or spherical driver section 11 are shown as driver elements 9. Of course, a single cylindrical pin 30 can also be provided as driver element 9, which is spherical or crowned at both ends in the area projecting beyond shaft outer surface 6 (= driver section 11). Only the area in which the cylindrical pin 30 is present and is arranged within the transverse bore 8 is cylindrical. For this z. B. offer a dowel pin with lens-shaped peaks at both ends. The axial groove recess 12 of this embodiment (Figure 5a) corresponds in terms of its cross section to the previously described axial groove recess 12, which has a groove base 17 which is aligned perpendicularly to the radial direction R and has side walls 13 inclined at an angle a to the radial direction R, so that overall a is formed in approximately trapezoidal cross-sectional space shape. The angle a between the side walls 13 and the radial direction R can be the same or different for both side walls 13, so that different contact patterns between the side walls 13 and the spherical and/or spherical driver section 11 are present at the contact points.

Those side walls 13 against which the driver elements 9 bear for torque transmission are to be understood as driver surfaces of the axial groove recesses 12 which cooperate with the driver sections 11 of the driver elements 9 in a force-transmitting manner during a rotating drive.

The configuration of the driver elements 9 described above as a pair of cylindrical pins 30 or a single cylindrical pin 30 can also be used without further ado in a shaft-hub connection 1 with the different embodiments of the axial groove recesses 12 described below.

The embodiments according to FIGS. 5b to 5f relate to different configurations of the axial groove recesses 12. The figures each show different variants of the axial groove recesses 12 in an engagement situation in the area of the driver element 9 shown in the drawing above. Of course, corresponding axial groove recesses 12 are also present and implemented in the area of the driver elements 9 shown in the drawing below.

Asymmetric groove shapes of the axial groove recesses 12 will be described with reference to FIGS. 5b to 5f, so that for their technical understanding it makes sense to specify a direction of rotation DR, ie a direction of load transmission. In the following descriptions, the shaft 2 of the shaft-hub connection 1 shown is a drive shaft, which torque on the Hubs 3 transmits. In the embodiments shown in the drawing, the direction of rotation DR of the shaft 2 is marked with an arrow. Due to their asymmetry, the embodiments of the different axial groove recesses 12 described below are mainly suitable for operation with only one direction of rotation D _R , as shown in FIGS. 5b to 5f. A direction of rotation opposite to the direction of rotation D _R and the resulting forces can be transmitted with the illustrated axial groove shapes of the axial groove recesses 12, but symmetrical axial groove recesses 12 are particularly suitable for such a load case (changing directions of rotation).

In Figure 5b, the axial groove recess 12 is designed as a groove with a semicircular cross section or at least a circular segment, the radius of which is slightly larger than the radius of the convex/spherical section of the driver element 9 or of the ball 10 present in the exemplary embodiment shown to bring snugly into contact with the groove surface of the axial groove recess 12, which reduces the surface pressures accordingly.

A further embodiment of the axial groove recess 12 is shown in FIG. 5c. In this embodiment, the axial groove recess 12 is provided with an inclined surface 18, seen in the direction of rotation DR, which has an angle α that is larger than the angle a in the embodiment according to FIG. 5a. In the present example, this angle is in particular approximately 45°. The groove base 17 is aligned perpendicularly to the radial direction R in this embodiment. A side wall 13 opposite the inclined surface 18 runs parallel to the radial direction R.

In the embodiment represented in FIG. In this embodiment, the side walls 13 run parallel to the radial direction R.

A further exemplary embodiment is shown in FIG. 5e. There, the axial groove recess 12 is formed as a quarter-circular groove in cross-section, which has a side wall 13 has, which is perpendicular to the radial direction R. The side wall 13 of this embodiment is formed by means of an arcuate wall 19, in particular in the shape of a quarter of a circle, the radius of which is greater than the radius of the protruding part (carrier section 11) of the carrier element 9, so that in this embodiment too a snug contact of the carrier element 9, in particular its crowned part or spherical protruding area.

In a further embodiment according to FIG. A side wall 13 runs parallel to the radial direction R. The groove bottom 17 is guided to the inner surface 5 of the hub by means of a curved wall 19a. A radius of the arcuate wall 19a is also chosen to be larger than the radius of the spherical driver element 9 or the protruding portion (driver section 11) of the driver element 9.

With the shaft-hub connection 1 according to the invention, it is possible with particularly simple means (configuration of the driver elements 9, e.g. as balls 10) and particularly simple manufacturing processes (drilling, turning, internal turning and broaching, possibly sintering), to To create connection 1, which on the one hand allows a good, form-fitting, in particular backlash-free torque transmission and on the other hand can compensate for an angular offset between the shaft center axis M and the hub axis N, which is in a range of a few degrees, in particular in a range between 0 ° and 3 °, more preferably between 0° and 1°.

Such a shaft-hub connection 1 is particularly suitable for use in a fluid pump (not shown), for example between a shaft 2, which is designed as a pump shaft 2a, and a hub 3, which is designed as a pump rotor 3a, for example.

FIG. 6 shows such a fluid pump 100 according to the invention in a longitudinal section, which has a shaft-hub connection 1 according to the invention. Such a fluid pump 100 has a drive housing 101 in which a drive motor 102 is arranged. The drive motor 102 has a drive shaft 103 which can be rotated about the central axis M by means of roller bearings 104 . Furthermore, the fluid pump 100 has a pump housing 105 in which a pump element 106 is arranged so as to be rotatable about the center axis M. The pump element 106 is non-rotatably connected to a shaft journal 107 via the shaft-hub connection 1 according to the invention. The shaft journal 107 thus corresponds to the shaft 2 described in the preceding description of the shaft-hub connection 1 according to the invention.

The pump element 106 corresponds to the pump rotor 3a described above. The pump element 106 has the widened hub opening 4a, through which the shaft journal 107 passes. Furthermore, the hub opening 4 is present, through which the shaft journal 107 also passes.

The shaft journal 107 has the transverse bore 8 in which the driver elements 9 are seated. The area of the driver elements 9 that protrudes beyond the outer surface of the shaft 6 is seated in the axial groove recesses 12.

In the embodiment according to FIG. 6, an elastic element, e.g. B. a compression spring used.

With the shaft-hub connection 1 according to the invention in the application of a fluid pump 100, it is possible in particular to compensate for an angular offset between the central axis M of the shaft 2/drive shaft 103/the shaft journal 107 and a hub axis N of the pump element 106/the hub 3. In this way, it can be advantageously achieved that the pump element 106 or the pump rotor 3a can be guided in the drive housing 101 or relative to the pump housing 105 with relatively little play, and pump gap losses can thus be minimized. The shaft-hub connection 1 according to the invention is particularly simple and inexpensive to produce and easy to assemble. Reference List

1 shaft-hub connection

2 wave

2a pump shaft

3 hub

3a pump rotor

4 hub opening

4a enlarged hub opening

5 hub inner surface

5a hub bridge

6 shaft outer surface

7 section

8 cross hole

9 driver elements

10 bullets

11 flight section

12 axial groove recess

13 side walls

14 annular gap

15 centering ring

15a support ring

16 intermediate piece

17 groove bottom

18 bevel

19; 19a arch wall

20 inside edge

30 cylindrical pins

31 cylinder section

100 fluid pump

101 drive housing

102 drive motor

103 drive shaft

104 rolling bearings

105 pump housing

106 pump element

107 Shaft journal

D diameter

D _R direction of rotation

D _w shaft diameter

M central axis

N hub axle

QA cross hole axis

A axial direction

R radial direction

U circumferential direction α angle

Claims

Expectations

Claims 1. Shaft-hub connection for a pump rotor (3a) on a pump shaft (2a), comprising: a shaft (2) with a shaft outer surface (6) and a central axis (M); a hub (3) having a hub opening (4) having a hub inner surface (5) for receiving at least a portion (7) of the shaft (2), the hub opening (4) having a hub axis (N); wherein the shaft (2) has at least one transverse bore (8) for receiving at least one driver element (9) and the hub inner surface (5) has at least one axial groove recess (12) corresponding to the at least one transverse bore (8) and, wherein in the at least at least one driver element (9) is accommodated in a transverse bore (8), which protrudes radially outwards at least in some areas of the shaft outer surface (6) and the protruding partial area (7) of the driver element (9) sits in the axial groove and the protruding partial area (7) of the Driver element (9) has a crowned or spherical surface, characterized in that the sum of the individual diameters of the driver elements (9) is greater than the shaft diameter (Dw) in the axial area of the transverse bore (8).

2. Shaft-hub connection according to claim 1, characterized in that the at least one driver element (9) is designed as a ball (10).

3. Shaft-hub connection according to claim 1 or 2, characterized in that the transverse bore (8) is a through transverse bore or a blind transverse bore.

4. Shaft-hub connection according to one of the preceding claims, characterized in that a transverse bore axis (QA) is aligned at right angles or at an oblique angle to the central axis (M).

5. Shaft-hub connection according to one of the preceding claims, characterized in that in the transverse bore (8) sits a plurality of directly or indirectly touching driver elements (9).

6. Shaft-hub connection according to one of the preceding claims, characterized in that the hub inner surface (5) with the exception of the axial groove is a cylindrical or part-cylindrical, d. H. cylindrical shell-shaped surface.

7. Shaft-hub connection according to one of the preceding claims, characterized in that an intermediate piece (16) is inserted between two adjacent driver elements (9).

8. Shaft-hub connection according to claim 7, characterized in that the intermediate piece (16) is elastically prestressed in order to prestress the driver elements (9) radially outwards.

9. Shaft-hub connection according to one of the preceding claims, characterized in that side walls (13) of the axial groove are designed to be inclined by an angle a with respect to a radial direction (R).

10. Shaft-hub connection according to one of the preceding claims, characterized in that the hub (3) is radially expanded axially adjacent to the hub inner surface (5) and forms an annular gap (14) with the shaft outer surface (6).

11. Shaft-hub connection according to one of the preceding claims, characterized in that the shaft (2) axially adjacent to the transverse bore (8) is formed radially reduced and forms an annular gap (14) with a hub inner surface (5).

12. Shaft-hub connection according to claim 11, characterized in that a centering ring (15) sits in the annular gap (14) for centering the hub (3) relative to the shaft (2).

13. Shaft-hub connection according to claim 11 or 12, characterized in that a support ring (15a) for limiting the axial displaceability of the shaft (2) relative to the hub (3) is seated in the annular gap (14).

14. Shaft-hub connection according to one of the preceding claims, characterized in that in the region of a radial outer edge of the transverse bore (8), the transverse bore (8) is reduced to a diameter (D) that is smaller than the diameter (D) of the driver element (8). is deformed radially inward.

15. Shaft-hub connection according to one of the preceding claims, characterized in that the axial extension of the hub inner surface (5) is greater than the diameter (D) of the driver element (9).

16. Shaft-hub connection according to one of the preceding claims, characterized in that the axial extension of the hub inner surface (5) is greater than the diameter (D) of the driver element (9) in a tangential plane to the shaft outer surface (6) and perpendicular to the transverse bore axis (QA) is.

17. Shaft-hub connection according to one of the preceding claims, characterized in that a driver surface of the axial groove recess (12) is curved in cross section.

18. Shaft-hub connection according to claim 17, characterized in that the driver surface of the axial groove recess (12) is curved in the same direction so as to nestle against the convex or spherical surface of the projecting portion (7) of the driver element (9).

19. Fluid pump with a drive shaft (103) and a pump rotor (3a), wherein at least one shaft-hub connection (1) is provided according to one of the preceding claims.

20. Fluid pump according to claim 19, characterized in that the shaft-hub

Connection (1) between the drive shaft (103) and the pump rotor (3a), the shaft-hub connection (1) according to one of claims 1 to 18 is provided.