DOUBLE-ROW ROLLING BEARING UNIT WITH PRE-CLAMPING ELEMENT

Description

[0001] The present invention relates to a double-row rolling bearing unit for a medical pump, comprising a bearing core that forms a first inner raceway facing in an axial direction for first rolling elements and a second inner raceway arranged axially opposite the first inner raceway for second rolling elements; a bearing bush that can be attached to a housing section and forms a first outer raceway opposite the first inner raceway; and a bearing cup that forms a second outer raceway opposite the second inner raceway. Furthermore, the present invention relates to a medical pump, preferably a syringe pump, with a corresponding double-row rolling bearing unit. Technical background

[0002] Today's medical therapies require high-precision medical pumps, which place stringent demands on installation space, weight, operational and functional reliability, and accuracy, among other things. Accordingly, the individual mechanical components are subject to tight tolerances, high miniaturization requirements, and may require complex installation and adjustment.

[0003] For example, syringe pumps such as the Perfusor ®< Space from B.Braun are often used in infusion therapy to administer fluids. These pumps enable flexible, safe therapies and must operate with high precision in order to accurately dose even minimal amounts of fluid. In such a syringe pump, a syringe filled with such a fluid is inserted into the pump and the syringe is then extruded via a drive head at a defined delivery rate (delivery mode), which is driven by a spindle. In this case, high axial loads are applied to the spindle at low speeds over a long period of time, up to several days. If the syringe needs to be changed, the drive head is retracted quickly, i.e. in just a few seconds, at high speeds and very low axial loads (return mode).Due to the high accuracy requirements, correspondingly high demands are placed on tolerances in the spindle bearings.

[0004] Currently, bearing concepts consisting of a large number of individual bearings are used for such precision applications. The components and assemblies required for the individual bearings must be stored, picked, and installed individually. The bearings are subject to complex adjustment during pump assembly, which is made even more difficult by the very limited installation space available and the stringent miniaturization requirements. In particular, fastening the bearing seats with screws is only possible to a limited extent or not at all due to the limited installation space of the pump. Accordingly, the pump assembly work is high, and costly and error-prone adjustment work is necessary, making reproducibly precise installation of the bearings difficult. Furthermore, these bearings may lack freedom of movement, which can lead to jamming of the bearings, particularly during installation.In addition, the bearing concepts currently in use involve high levels of friction.

[0005] For example, DE 80 09 464 U1 discloses a bearing with a support plate, an outer housing, and an inner ring, as well as two axially arranged rows of balls. The inner ring comprises two deep-drawn sheet metal shells, each with a grooved inner raceway; and the outer ring comprises deep-drawn sheet metal parts with grooved outer raceways. One of the sheet metal parts has an axially outwardly projecting ring land that clampingly engages the end edge of the other sheet metal part. DE 80 09 464 U1 discloses a double-row rolling bearing unit according to the preamble of claim 1.

[0006] DE 10 2006 034729 B3 relates to a double-row spherical roller or ball bearing in which rolling elements are arranged between two inner ring raceways and two outer ring raceways. Both the inner ring raceways and the outer ring raceways are formed by sheet metal. The inner ring raceways are supported by two support bodies. The two support bodies are equipped with means that enable a positive connection of the two support bodies for non-displaceable cohesion in the axial direction. The means are designed like a zipper, namely, in that hook-shaped projections and undercuts interact in the two support bodies to be connected to each other.

[0007] US 2010 / 284643 A1 discloses a rolling bearing with an inner and outer bearing ring, in which at least one of the bearing rings is divided into two identically shaped ring halves. Locking elements are formed on a radially inner or radially outer ring part. Segment-like and shell-shaped projections protrude axially beyond the ring part along part of its circumferential extent. The projections are arranged in a different radial plane than the locking elements, which are circumferentially delimited by segment-like recesses, and the projections of one ring half engage in the complementarily shaped recesses of the other ring half, so that the projections and the ring part overlap in the axial direction and the locking elements of one ring half engage in recesses arranged in the other ring part.

[0008] Accordingly, the object of the present invention is to eliminate or reduce disadvantages known from the prior art, and in particular to simplify the assembly of medical pumps, to make it safer, more precise and reproducible and to reduce manufacturing costs. Summary of the invention

[0009] The object underlying the invention is achieved by a double-row rolling bearing unit for a medical pump, preferably a syringe pump, comprising a bearing core forming a first inner raceway, partially facing in an axial direction, for first rolling elements, and a second inner raceway, partially arranged in the axial direction opposite the first inner raceway, for second rolling elements. Furthermore, the pump has a bearing bush, which can be attached to a housing section or a bearing plate and forms a first outer raceway, opposite the first inner raceway, for the first rolling elements, as well as a bearing cup or bearing cover, which forms a second outer raceway, opposite the second inner raceway, for the second rolling elements.At least one preload element is provided, which couples the bearing cup to the bearing bush with a defined preload / adjustment to form the easily preassembled, double-row rolling bearing unit. Preferably, the preloaded rolling bearing unit can be installed in the pump without preload adjustment.

[0010] The rolling bearing unit also features radially outwardly projecting support elements, which are provided for support in a second load direction on the housing section. The support elements are elastic in order to be able to deflect radially inward. In particular, the first load direction is a secondary load direction, in which forces act, for example, during a return operation of the syringe pump. Support elements that can deflect radially inward simplify the installation of the rolling bearing unit in the pump, as they can be pushed out of the way. Furthermore, the springing back of the support elements can serve as a signal that the correct installation position has been reached.

[0011] In other words, an adjusted bearing in an X or O arrangement is provided, which is provided by at least one preloading element as a preassembled and preloaded, play-free unit. In the context of the present invention, a bearing with an X arrangement means that two combined angular contact bearing sections are arranged in a mirror image of one another such that pressure lines (directions along which forces are transmitted in a row of rolling elements) intersect in the corresponding bearing axis and point in the direction of the respective opposite row of rolling elements or the opposite angular contact bearing section. In an O arrangement, these pressure lines run in the opposite direction, i.e. in the radially inward direction away from the opposite angular contact bearing section. Such a bearing enables very tight, precise guidance of a shaft or spindle of the medical pump.Furthermore, the number of required components is significantly reduced compared to a conventional bearing arrangement, thus reducing costs. Suitable rolling elements include cones, rollers, or needles, as well as preferably balls, barrels, and spherical rollers. The first and second rolling bearings can be shaped and / or dimensioned differently depending on the loads encountered. The rolling bearing unit is preferably lubricated for life.

[0012] Preferably, the bearing bush can be attached to the housing section via a fitting section, wherein the bearing cup is arranged along the axial direction next to the fitting section and not overlapping it. In other words, the fitting section and the bearing cup are preferably offset from one another or spaced from one another in the axial direction when the bearing unit is assembled. Further preferably, the at least one preloading element is an elastic section of the bearing cup that at least partially encompasses the bearing bush. In other words, the bearing cup and the preloading element are formed from a single piece of material. In particular, the bearing cup is slotted at its end facing the bearing bush, and webs remaining between the slots are elastically bendable in order to form a plurality of preloading elements.Advantages of this design are that a radial installation space of the bearing unit can be reduced and / or the assembly thereof is simplified and / or the machining of the bearing seat is easier and / or the at least one preloading element can be advantageously designed with regard to its flexibility and handling.

[0013] A rolling bearing unit according to the invention makes it possible to significantly reduce the effort required for its installation in the pump and the associated preparation. Instead of several different bearings, the rolling bearing unit can be transported, stored and commissioned as a single, pre-assembled module and then installed in the pump without the need for a work step to adjust the preload of the bearing. For example, the rolling bearing unit can be pressed onto a shaft or spindle of a pump and fastened to the pump housing via a fitting section provided either on the bearing cup or on the bearing bush. Alternatively, the rolling bearing unit can be glued, pressed or screwed into the pump housing, for example. For this purpose, a thread can be provided on an outer circumference of the rolling bearing unit, for example.

[0014] Furthermore, various designs of the at least one preload element are conceivable. It can be provided as a separate, elastic component, such as a tension or compression spring inserted into the rolling bearing unit, or as a group of separate, elastic components, preferably arranged at equal intervals around the circumference of the rolling bearing unit. It is also conceivable to provide a threaded element provided on the bearing cup and / or the bearing bush as the preload element, thus clamping the bearing cup and the bearing bush together using a screw thread, in particular an adjusting thread.

[0015] It has proven particularly expedient for the at least one preloading element to be at least one elastic section of the bearing cup or the bearing bush, preferably a number of snap hooks. Further preferably, a number of preloading elements are distributed at equal intervals around the circumference of the bearing bush or the bearing cup. This at least one preloading element accordingly encompasses the bearing bush or the bearing cup at least partially or engages therein. The at least one preloading element is thus integrally connected to other components of the rolling bearing unit, so that the number of components required can be reduced, the weight of the rolling bearing unit can be optimised and manufacturing costs can be lowered. In particular, the design of the preloading element as an encompassing / enclosing elastic component such as e.g.B Snap hooks, that the preload of the rolling bearing unit is determined by this elasticity and a structural design. This is a significant simplification, particularly given the miniaturization of the rolling bearing unit required by the limited installation space. Compared to adjustment using an adjustment thread, for example, this has the advantage that the pre-assembly of the rolling bearing unit is significantly faster and the high tolerance requirements are reliably met, since the process is more reproducible, i.e., less subject to human error. This significantly reduces manufacturing costs.

[0016] An advantageous embodiment of the rolling bearing unit according to the invention provides that the first rolling elements and first raceways form an X-arranged bearing arrangement with the second rolling elements and second raceways. In particular, it is preferred that the first and / or second rolling elements enable a wobbling movement of the bearing core relative to the bearing cup and the bearing bush (freedom from wobbling), preferably within an angular range of + / -1° around the bearing or longitudinal axis.

[0017] Freedom from wobble in the rolling bearing unit is important for the fastest, most reproducible, and safest installation of the rolling bearing unit according to the invention, since the shaft or spindle of the medical pump cannot usually be installed perfectly coaxially with the bearing axis and / or with a bearing seat provided on the housing section. During installation, particularly when handling the spindle or shaft, slight angular deviations occur, which must be permitted by the rolling bearing unit. An X-arrangement of the first and second rows of rolling bearings has a relatively large tilting clearance, i.e., it is suitable for allowing slight angular deviations between the bearing core, the bearing bush, and the bearing cup without jamming. Furthermore, according to this preferred embodiment of the invention, rounded rolling elements, i.e., barrels, spherical rollers, or preferably balls, are used to enable wobble.

[0018] The bearing bush can expediently form a radially outwardly projecting flange, which is provided for support in a first load direction on the housing section.

[0019] Since the rolling bearing unit is installed in such a way that the flange rests against the housing section, the flange determines the axial installation position of the rolling bearing unit. This is important for the precise and reproducible installation of the rolling bearing unit in the medical pump. Furthermore, the flange serves to support the axial forces transmitted from the rolling bearing unit to the housing section in the first load direction, which preferably corresponds to a main load direction, for example, during delivery operation of the medical syringe pump. If both the flange and the support elements are provided, the rolling bearing unit is secured axially in both directions with positive locking.

[0020] The rolling bearing unit according to the invention is designed such that the at least one preloading element has one or more hold-down devices which are configured to be supported radially outward on the housing section in order to press the at least one preloading element into an associated engagement contour when the double-row rolling bearing is installed in the housing section. This is particularly advantageous if snap hooks are provided as preloading elements which, with a radially inwardly projecting projection, at least partially encompass or engage the bearing bush or bearing cup, wherein the snap hooks must be bent radially outward during (pre-)assembly and disassembly of the rolling bearing unit. The hold-down devices prevent the snap hooks from bending outward when the rolling bearing unit is installed in the pump and thus serve as a self-locking device against the bearing unit opening during operation.This is particularly advantageous if the medical pump is a syringe pump with a pull spindle, since in such a case, high tensile forces are applied to the rolling bearing unit during conveying operation, which could cause the snap connection to open unintentionally.

[0021] Alternatively, it is conceivable to provide a retainer, particularly in the form of a circumferential, radially inwardly projecting projection or step, on the housing section, which presses against the preload elements or snap hooks from the radial outside. Depending on the structural design of the housing section and the requirements it is subject to, this solution is more cost-effective than one in which the retainer is formed by the preload elements.

[0022] In summary, it should be noted that the rolling bearing unit according to the invention, in its simplest form, provides preloading elements. The support sections and the hold-down devices are advantageous embodiments of the invention, which can be provided individually or in combination, and optionally formed as a single piece, in order to achieve the advantageous effects described above.

[0023] The rolling bearing unit is backlash-free and compact. Its installation into the medical pump is very simple and reproducible, as no adjustment work or preload checks are required. Unit costs are low, as the individual components of the rolling bearing unit can be manufactured cost-effectively using high-volume processes, such as injection molding from triboplastic. Likewise, the (pre-)assembly of the rolling bearing unit itself, especially in the version with snap hooks, is quick, cost-effective, and reproducible, as the components, especially the snap hooks, are self-adjusting.

[0024] The rolling bearing unit is pre-assembled by inserting the rolling elements, in particular balls, and the bearing core into the bearing bush or bearing housing, which are then clamped to a defined level of play by attaching, in particular snapping on, the bearing cup or bearing cover. The bearing cup presses against the balls, which form a stop or limiter of the preload travel. Furthermore, when the bearing cup is snapped on, the balls are pressed into their intended operating positions or come to rest in their predetermined running surfaces / raceways. This creates a bearing element that is clamped to a zero-play X-axis. This means that the preload is achieved through the assembly of the rolling bearing unit itself. The bearing cup, particularly the version with snap hooks, is resilient due to its shape and can be hooked into a locking geometry during assembly.This applies a permanent (preload) force to the rotating inner rotor / bearing core. Both the assembly of the rolling bearing unit itself and its installation in the pump are easily automated.

[0025] Furthermore, the object underlying the invention is achieved by a medical pump, preferably a syringe pump, which has a spindle, preferably a pull spindle, which is rotatably and axially fixedly mounted in a housing section of the medical syringe pump by a double-row rolling bearing unit according to the above description.

[0026] The preassembled rolling bearing unit can be installed in the pump using a press-in tool, which may be miniaturized. It is pressed into any bore with a corresponding fit. The strength of the connection is defined by the fit between the bore and the bearing unit and by the shear strength of a bearing collar (fit section). Character description

[0027] The present invention will be described below using exemplary embodiments with reference to the accompanying drawings, but the invention is not intended to be limited thereto. The same reference numerals are used for the same elements. Fig. 1 shows a syringe pump in which a double-row rolling bearing unit is installed. Fig. 2 shows a perspective view of the double row rolling bearing unit according to an example for understanding the invention. Fig. 3shows a longitudinal section view of the double-row rolling bearing unit according to the example of Fig. 2 . Fig. 4 shows a perspective view of the double-row rolling bearing unit according to an embodiment of the invention. Fig. 5 shows a longitudinal sectional view of the double row rolling bearing unit according to the embodiment of the invention.

[0028] At the Fig. 1The medical pump shown is a syringe pump 1, which is used, for example, in infusion therapy. The syringe pump 1 has a syringe housing 2 with a receiving compartment 3, which serves to receive and, if necessary, hold a syringe 4 (shown schematically here). When the syringe pump 1 is in operation, a syringe 4 filled with medication or the like, with a syringe plunger 5 for expelling the syringe 4, is inserted into the receiving compartment 3 and rests against a drive head 6 of the syringe pump 1. The drive head 6 is axially displaceable in order to actuate the syringe plunger 5. It is connected to a spindle 8, more precisely a pull spindle, via a drive tube 7 mounted axially displaceably on the syringe housing 2. Between the drive tube 7 and the spindle 8, a conversion mechanism (not shown) is provided, which converts a rotational movement of the spindle 8 into a longitudinal movement of the drive head 6.

[0029] For better orientation, the side of the syringe pump 1 and the roller bearing unit 9 facing toward the drive head 6 or in a tensile direction is referred to below as the front side. The opposite side or direction of the syringe pump 1 and the roller bearing unit 9, facing toward the gear section 12 or in a compressive direction, is referred to as the rear side.

[0030] The spindle 8 is rotatably and axially fixedly mounted on the syringe housing 2 by a double-row rolling bearing unit 9. According to this embodiment, the double-row rolling bearing unit 9 sits in a bearing seat 11 formed by a bearing plate 10. The bearing plate 10 is a housing section that serves to separate a gear section 12 in the syringe housing 2, in which drive gears 13 are arranged for driving the spindle 8. The drive gears 13 are also mounted on the bearing plate 10. An electric motor (not shown) is also provided to drive the drive gears 13.

[0031] The following with reference to Fig. 2 and Fig. 3 The example described is only intended to help understand the subsequent explanations with reference to Fig. 4 and 5 described embodiment of the present invention.

[0032] Fig. 2is a perspective view of the double-row rolling bearing unit 9. An outer bearing ring of the rolling bearing unit 9 is two-part and has a bearing bush 14 and a bearing cup 17. The bearing bush 14 forms an engagement contour on the outside in the form of a circumferential groove 15, into which snap hooks 16 of the bearing cup 17 engage. The snap hooks 16 serve as a preload element, by means of which a defined preload / adjustment of the rolling bearing unit 9 is generated. The snap hooks 16 are formed in that the bearing cup 17 has, on its rear side (i.e., in the installed state facing the bearing plate 10 of the syringe housing 2), sleeve-shaped end, slots 18 distributed at equal intervals around the bearing circumference, which run in the axial direction. Elastic webs, the snap hooks 16, remain between the slots 18. On its front side (i.e.At the end facing away from the bearing plate 10 of the syringe housing when installed, the bearing cup 17 is curved radially inward in a bowl-like manner and is open in the axial direction. Arranged within the bearing bush 14 and the bearing cup 17 is a bearing core 19, the front end of which, as shown in FIG. Fig. 2 shown, lies radially within an opening of the end of the bearing cup 17 facing away from the bearing plate 10. The rolling bearing unit 9 is mounted as a preassembled unit on the bearing plate 10 by the bearing bush 14 being pressed into the bearing plate 10.

[0033] Fig. 3 shows a longitudinal section of the rolling bearing unit 9 of the Fig. 2described example. A position of the rolling bearing unit 9 in the axial direction is determined by the fact that a collar or flange 20 formed by the bearing bush 14 and extending radially outwards rests on the rear side (i.e., on the side of the gear section 12 or on the side facing away from the drive head 6) of the bearing plate 10. Furthermore, a tensile load acting on the spindle 8 during conveying operation (i.e., a main load acting in the tensile direction, in the direction of the drive head 6) is supported on the bearing plate 10 by the flange 20. A chamfer 21 is provided around the bearing seat 11 on the rear side of the bearing plate 10 in order to facilitate pressing in or installing the bearing bush 14 on the circuit board 10.Immediately in front of the flange 20, the bearing bush 14 has a fitting section 22 which extends in the axial direction and via which the bearing bush 14 is pressed into the bearing seat 11 formed by the bearing plate 10, as described above. Through the press connection thus created, a compressive load acting on the spindle 8 (i.e., a secondary load acting in the compressive direction or toward the rear) is transferred to the bearing plate 10. Immediately behind the fitting section 22, the bearing bush 14 forms, in the following sequence, a radially inwardly extending step, the circumferential groove 15, and an end section extending in the axial direction toward the front.

[0034] On an inner side of the bearing bush 14, more precisely, on a section of the bearing bush 14 located radially within the fitting section 22 and the bearing seat 11, a radially inwardly extending collar is provided, which forms a first outer raceway 23 in the design of an angular contact ball bearing on its front side. The first outer raceway 23 supports first rolling elements 24, in this example, balls, on the rear side and radially outward.

[0035] Arranged within the bearing bush 14 is the bearing core 19, which is essentially sleeve-shaped and forms a spindle seat 30 on an inner circumferential surface for connection to the spindle 8. The spindle seat 30 is preferably a slight clearance or transition fit, but can also be designed as a press fit. In a central region, the bearing core 19 further has a radially outwardly projecting projection 25. At a transition between the projection 25 and the rear end of the bearing core 19, a first inner raceway 26 in the style of an angular contact ball bearing is formed for the first rolling elements 24, which is diametrically opposite the first outer raceway 23 such that the first rolling elements 24 roll between the first inner raceway 26 and the first outer raceway 23 during relative rotation of the bearing core 19 and the bearing bush 14.

[0036] At a transition between the projection 25 and the front end of the bearing core 19, a second inner raceway 27 in the form of an angular contact ball bearing is formed to support second rolling elements 28, in this example balls, at the rear and radially inward. Diametrically opposite the second inner raceway 27, on an inner side of the bearing cup 17, more precisely within its bowl-shaped end, a second outer raceway 29 in the form of an angular contact ball bearing is formed to support the second rolling elements 28 at the front and radially outward. This means that the second inner and outer raceways 27, 29 are arranged opposite one another in such a way that the second rolling elements 28 roll between the second inner raceway 27 and the second outer raceway 29 during relative rotation of the bearing core 19 and the bearing cup 17.

[0037] In addition, Fig. 3It is clearly visible that the snap hooks 16 formed by the bearing cup 17 engage in the circumferential groove 15 of the bearing bush 14, thereby holding the rolling bearing unit 9 together. Furthermore, it can be seen that the free ends of the snap hooks 16, which engage in the circumferential groove 15, are bent radially inward and form a ramp or mounting bevel 37 at their rear end or rear end face, through which the snap hooks 16 come into contact with the bearing bush 14 during an assembly process and are pressed or bent outward.More precisely, during assembly of the rolling bearing unit 9, the bearing core 19 and the rolling elements 24, 28 are inserted into the bearing bush 14 and the bearing cup 17 is pushed over the bearing bush 14 from the front, whereby the snap hooks 16 meet the front end of the bearing bush 14 and are elastically bent outwards by the front-side assembly bevels 37 until the snap hooks 16 finally snap into the circumferential groove 15 of the bearing bush 14. In this case, the snap hooks 16 cannot fully elastically return to their original position, but rather press against a front wall of the circumferential groove 15, whereby a defined preload or adjustment of the rolling bearing unit 9 is achieved.

[0038] Furthermore, Fig. 3It can be seen that the step of the bearing bush 14 formed immediately behind the fitting section 22 extends radially outward beyond the outer circumference of the bearing cup 17 and thereby shields the snap hooks 16 in the axial direction. This prevents, particularly in a pre-assembled, uninstalled state of the rolling bearing unit 9, an obstruction from reaching behind the snap hooks 16 and unintentionally opening them, which would cause the rolling bearing unit 9 to fall apart.

[0039] When a tensile load is applied to the spindle 8, ie during delivery operation of the syringe pump 1, a corresponding tensile force is transmitted via the spindle seat 30 (in the case of a press fit of the spindle seat 30) or via the rear end face 35 (in Fig. 3left) of the bearing core 19 (in the case of a clearance or transition fit of the spindle seat 30) is transferred to the bearing core 19. For this purpose, it is advantageous if the bearing core 19 protrudes from a corresponding opening in the bearing bush 14. From the bearing core 19, the tensile force is transferred via the second inner raceway 27 of the bearing core 19 to the second rolling elements 28 and from there to the second outer raceway 29 of the bearing cup 17. The tensile load thus acting on the bearing cup 17 is transferred via the snap hooks 16 to the bearing bush 14 and from there via the friction in the press connection between the bearing bush 14 and the bearing plate 10 and via the flange 20 to the bearing plate 10. The flange 20 is required because relatively high forces act on the spindle 8 during conveying operation. In the opposite operating direction, ieDuring a reset operation of the syringe pump 1, a comparatively low pressure load acts on the spindle 8, which is connected to the spindle via the spindle seat 30 or, if applicable, via a front end face 36 (in . Fig. 3 right) of the bearing core 19 to the bearing core 19. From there, the compressive load is transferred via the first inner raceway 26 and the first rolling elements 24 to the first outer raceway 23 of the bearing bush 14 and from there via the friction in the press connection between the bearing plate 10 and the bearing bush 14 to the bearing plate 10. According to this example, the first and second rolling elements 24, 28 are designed according to the different loads in the tensile and compressive directions, so that smaller balls are selected as the first rolling elements 24 (e.g. with a diameter of 2 mm) than for the second rolling elements 28 (e.g. with a diameter of 3 mm).

[0040] Fig. 4shows a perspective view of a rolling bearing unit 9 according to an embodiment of the invention. The structure of the syringe pump 1, the rolling bearing unit 9 itself, and its installation situation largely correspond to that of the previous example, which is why only differences between the embodiment and the previous example are explained below to avoid redundant descriptions.

[0041] When comparing Fig. 4 with Fig. 2 It becomes clear that the biggest difference between the embodiment and the example lies in the design of the bearing cup 17, more precisely in the design of the sleeve-shaped section of the bearing cup 17 extending in the axial direction, which forms the prestressing elements or snap hooks 16. The snap hooks 16 are arranged at equal intervals around the circumference of the bearing cup 17. The snap hooks 16 are arranged according to this in Fig. 4illustrated embodiment from substantially cross-shaped sections made of sheet metal, plastic or other elastically deformable materials (in particular from the same material and in one piece with the rest of the bearing cup). The foot 31 of this cross is integrally connected to the bowl-shaped end of the bearing cup 17 and extends axially towards the bearing plate 10 or in the compression direction. Two arms 32 of the cross extend on either side of the foot 31 in the circumferential direction or perpendicular thereto and are bent radially inwards with their free ends in order to engage in the circumferential groove 15. In this way, the rolling bearing unit 9 is connected as a unit and the preload of the rolling bearing unit 9 is provided. A head 33 of the cross basically represents an extension of the foot 31 beyond the arms 32 and is bent radially outwards.The free end of the head 33 rests against an inner circumferential surface of the bearing seat 11 formed in the bearing plate 10, whereby the cross-shaped snap hooks 16 are elastically pressed radially inward when installed or are at least held in the position engaging in the circumferential groove 15. This means that the head 33 of the cross serves as a hold-down device to secure the engagement of the arms 32 of the cross in the circumferential groove 15, thus preventing them from snapping out even under high tensile loads.

[0042] In addition, the sleeve-shaped section of the bearing cup 17 extending in the axial direction forms elastic support elements 34. These are arranged around the circumference of the bearing cup 17, alternating with the snap hooks 16, at equal distances from one another. The support elements 34 are bent obliquely radially outwards in such a way that they are supported on the outside on the forward-facing surface of the bearing plate 10, in order to, on the one hand, realize a self-locking of the rolling bearing unit 9 in the bearing plate 10 and, on the other hand, to transmit forces to the bearing plate 10 in a form-fitting manner in the compression direction, instead of, as in the example according to Fig. 2 and Fig. 3 , to be implemented exclusively by frictional engagement via the press connection with the bearing seat 11.

[0043] Furthermore, the support elements 34 are integrally connected to the bowl-shaped end of the bearing cup 17 via a widened base extending parallel to the bearing axis and further have a narrower free end connected to the base, which, as described above, is bent radially outwards in order to be supported on the bearing plate 10. Due to manufacturing reasons, the base of a support element 34 lies between the feet 31 of two cross-shaped snap hooks 16 and the base ends in the axial direction just in front of two arms 32 of two snap hooks 16. For example, this enables a simple, uniform cutting width in order to introduce the snap hooks 16 and the support elements 34 into the one-piece bearing cup 17. It should be noted that in this specific embodiment, both the snap hooks 16 and the support elements 34 are provided.

[0044] Fig. 5shows a longitudinal section through the rolling bearing unit 9 of the embodiment along a plane which runs through the bearing axis L and intersects support elements 34 which are diametrically opposite one another with respect to the rolling bearing unit 9. In this view, it is clearly visible that the bearing plate 10 is slightly beveled at the forward-facing peripheral edge of the bearing seat 11 in order to enable better support of the free ends of the support elements 34 on the bearing plate 10. Because the support elements 34 are elastic, they can deflect to enable the bearing to be fitted into the bearing seat 11 of the bearing plate 10 starting from the side of the gear section 12. In the end position or when the installed state is reached, the support elements 34 leave the bearing seat 11 and snap outwards in order to be axially supported on the bearing plate 10.

[0045] Furthermore, behind one of the support sections 34 (in the Fig. 5A snap hook 16 can be seen, the head 33 of which rests radially against the inner circumferential surface of the bearing seat 11 of the bearing plate 10. It can also be clearly seen that the fitting section 22 of the bearing bush 14 is smaller than that of the example according to Fig. 2 and Fig. 3 is relatively short and does not extend beyond the bearing seat 11 of the bearing plate 10 in the axial direction, so that a section of the bearing seat 11 is exposed, against which the heads 33 of the snap hooks 16 can be supported. Furthermore, an arm 32 of the snap hook 16 can be seen, which engages in the circumferential groove 15 of the bearing bush 14 and also forms a ramp or mounting bevel 37 on its rear end face, by means of which the snap hook 16 is pressed radially outwards when the bearing cup 17 is snapped onto the bearing bush 14.

[0046] In other words, in the embodiment, the geometry of the bearing cup 9 is expanded in such a way that after pressing into the bearing seat 11, retaining tabs or support elements 34 engage and the bearing is also positively engaged in the pressure direction and not only frictionally engaged, as in the example according to Fig. 2 and Fig. 3 , secure. In addition, the hold-down devices 33 prevent the locking geometries (snap hooks 16) on the bearing cup 17 from opening under tensile forces Z.

[0047] Fig. 4 and Fig. 5 also show the rolling bearing unit 9, to which both the spindle 8 and one of the drive gears 13 are already attached. This installation situation is equally applicable to the example according to Fig. 2 and Fig. 3 transferable.

[0048] The rolling bearing unit 9 according to the example described above Fig. 2 and Fig. 3is particularly simple and cost-effective and is particularly advantageous in the case of relatively low loads. However, if the rolling bearing unit 9 is subjected to higher loads, the rolling bearing unit 9 according to the embodiment described above may be advantageous, since it has additional securing and fastening features through the hold-down devices 33 and support elements 34 to absorb higher loads without increasing the number of required components, the effort of (pre-)assembly, or the installation of the rolling bearing unit 9 according to the invention into the syringe pump 1. Reference character list

[0049] 1Medical pump / syringe pump 2Syringe housing 3Receiving compartment 4Syringe 5Syringe plunger 6Drive head 7Drive tube 8Spindle 9Rolling bearing unit 10Bearing plate 11Bearing seat 12Gear section 13Drive gears 14Bearing bush 15Circumferential groove 16Snap hook / preload element 17Bearing cup 18Slots 19Bearing core 20Flange 21Chamfer 22Fitting section 23First outer raceway 24First rolling elements 25Protrusion 26First inner raceway 27Second inner raceway 28Second rolling elements 29Second outer raceway 30Spindle seat 31Snap hook base 32Snap hook arms 33Snap hook head / hold-down device 34Support element 35Rear end face of the bearing core 36Front end face of the bearing core 37Mounting slope LLongitudinal axis of the rolling bearing unit / bearing axis

Claims

1. Double-row roller bearing unit (9) for supporting movable, rotating components of a medical pump (1), preferably a syringe pump, having a bearing core (19) which forms a first inner bearing surface (26), partially facing in an axial direction, for first rolling elements (24) and a second inner bearing surface (27), partially arranged opposite the first inner bearing surface (26) in the axial direction, for second rolling elements (28); a bearing sleeve (14) which can be attached to a housing portion (10) and forms a first outer bearing surface (23), opposite the first inner bearing surface (26), for the first rolling elements (24); and a bearing pan (17) forming a second outer bearing surface (29), opposite the second inner bearing surface (27), for the second rolling elements (28); and at least one pre-loading element (16) which couples the bearing pan (17) to the bearing sleeve (14) with a defined pre-load in order to form the handleably preassembled double-row roller bearing unit, wherein the pre-loading element (16) is an elastic portion of the bearing pan (17) or of the bearing sleeve (14) which correspondingly at least partially embraces or engages the bearing sleeve (14) or respectively the bearing pan (17), characterized in that the at least one pre-loading element (16) comprises one or more hold-down devices (33) configured to rest against the housing portion (10) radially outwards in order to press the at least one pre-loading element (16) into an associated engagement contour (15) when the double-row roller bearing unit (9) is installed in the housing portion (10), and support elements (34) projecting radially outwards are provided, which are provided for support at the housing portion (10) in a second axial load direction and which are elastic in order to be able to deflect radially inwards.

2. Double-row roller bearing unit (9) according to claim 1, characterized in that the pre-loaded double-row roller bearing unit (9) can be installed in the pump (1) without pre-load adjustment.

3. Double-row roller bearing unit (9) according to claim 1 or 2, characterized in that the elastic portion of the bearing pan (17) or of the bearing sleeve (14) is provided in the form of snap hooks.

4. Double-row roller bearing unit (9) according to one of the preceding claims, characterized in that the first rolling elements (24) and first bearing surfaces (23, 26) form an X-arranged bearing arrangement with the second rolling elements (28) and second bearing surfaces (27, 29).

5. Double-row roller bearing unit (9) according to one of the preceding claims, characterized in that the first and / or second rolling elements (24, 28) are rounded rolling elements and allow a wobbling movement of the bearing core (19) relative to the bearing pan (17) and the bearing sleeve (14).

6. Double-row roller bearing unit (9) according to one of the preceding claims, characterized in that the bearing sleeve (14) forms a flange (20) projecting radially outwards which is provided for support at the housing portion (10) in a first second axial load direction.

7. Double-row roller bearing unit (9) according to one of the preceding claims, characterized in that the sleeve-shaped portion of the bearing pan (17) that extends in the axial direction forms the support elements (34).

8. Double-row roller bearing unit (9) according to claim 7, characterized in that the support elements (34) are arranged alternatingly with the pre-loading elements (16), which form snap-fit hooks, around the bearing pan (17) at equal distances.

9. Double-row roller bearing unit (9) according to claim 8, characterized in that the support elements (34) are bent obliquely outwards in a radial direction, so that they are supported on the outside of the forward-facing surface of the housing portion (10), which is a bearing plate.

10. Medical pump (1), preferably a syringe pump, having a spindle (8), preferably a traction spindle, which is mounted rotatably and axially fixed in a housing portion (10) of the medical pump (1) by a double-row roller bearing unit (9) according to one of the preceding claims.