Hose roller pump

Abstract

The invention relates to a peristaltic pump, in particular for conveying a fluid in a device for extracorporeal blood treatment, comprising a pump housing in which a rotor, which can be rotated about a rotor axis and which has at least two pressing elements that are offset from one another in the circumferential direction, is accommodated. The pump housing has a support surface extending arcuately about the rotor axis and spaced radially from the rotor, the support surface being arranged to support a hose segment that can be introduced radially between the rotor and the support surface. The rotor is driven by means of a rotor shaft, the rotational movement of which can be transmitted to the rotor base body by means of a freewheel pressed into the toothed drive sleeve. Sliding bearing points for the rotor base body are provided on both sides of the freewheel. In order to ensure the coaxiality between the freewheel and the anti-tilt bearing of the rotor base body at low production costs, the sliding bearing points are determined on both sides of the freewheel by the geometry of the machined drive sleeve.

Description

Technical Field

[0001] The present disclosure relates to a hose roller pump or peristaltic pump, i.e. a positive displacement pump, in which the medium to be conveyed is squeezed through the hose by external mechanical deformation of the hose. Such pumps are usually used in devices for extracorporeal blood treatment, in particular dialysis machines, for conveying fluids, in particular blood. The fluid is conveyed from the low-pressure side to the high-pressure side by means of a peristaltic pump, wherein an elastically deformable fluid line in the form of a hose segment (the hose segment is also referred to as a pump segment) arranged between the low-pressure side and the high-pressure side is deformed, in particular squeezed, by means of at least two squeezing elements between a support surface of a pump bed and a rotor rotating relative to the support surface. Background Art

[0002] Peristaltic pumps of the type described are available on the market in different embodiments. In a pump such as that manufactured by the applicant of document EP 1 749 549 B1, the structure of the pump can be varied according to the invention. Figure 8 As can be seen from the schematic sectional view of , the torque is transmitted from a drive shaft 310 with an axis A by means of a freewheel 320 and a knurled sleeve 330. The rotor base body 340 is supported on the drive shaft via a small sliding bearing 350 at the free end of the drive shaft, wherein the sliding bearing 350 is axially offset relative to the knurled sleeve 340, which extends only to the center of the rotor base body 340. The sliding bearing 350 is integrated into the base body 340 of the rotor.

[0003] In order to ensure the coaxiality between the freewheel 310 and the bearing 350, high demands must be made on the precision of the knurled sleeve and the base body. In addition, since only a small one-sided support of the rotor base body 340 is provided, radial forces and tilting moments can only be absorbed to a limited extent. Although the knurled sleeve has knurling over the entire height, due to its small axial extension height and installation in the axially outer area of ​​the base body of the rotor base body 340, the torque to be transmitted is introduced only in the lower area and thus remains relatively limited.

[0004] Other peristaltic pumps of this type are known, such as the Fig. 9 and 10 Structured as shown in . Fig. 9 shows a partial section through a rotor base body with a pressed-in freewheel, and Fig.10A sectional view of the knurled sleeve and the support ring used here is shown. In this peristaltic pump, the torque transmission from the drive shaft to the rotor base 440 is also achieved via the freewheel 420, which is pressed into the knurled sleeve 430. The knurled sleeve 430 is in turn pressed into the cylindrical recess of the rotor base 440. The freewheel is provided to enable manual insertion and removal of the pump segments and manual return of the blood without having to open the locking part. The sleeve freewheel without rolling bearings is a friction coupling and can only transmit torque. Since they cannot withstand radial forces or tilting moments, the support part of the rotor base 440 has two sliding bearing parts, which are indicated by the reference numerals 450A and 450B. The edge-side support part 450A is integrated into the knurled sleeve 430 below the freewheel, as shown in Fig. 9 The knurling 435 is arranged radially outside the bearing portion 450A, that is, at a location where the wall thickness of the knurled sleeve 430 is greater. The second bearing portion 450B forms a separate bearing ring 470, which is arranged according to Figure 8 It is pressed into an offset hole in the base body of the rotor base body 440 above the knurled sleeve 430. This design requires high manufacturing precision both in the parts of the knurled sleeve 430 and the bearing ring 470 and in the receptacle in the rotor base body 440 in order to ensure coaxiality between the freewheel 430 and the bearings 450A, B. It has also been found that the transferable torque remains limited in this design, since it can only be introduced via the knurling 435 arranged on the edge. Summary of the invention

[0005] The object of the present invention is to provide a peristaltic pump in which the coaxiality between the freewheel and the bearing is ensured with low production outlay while maintaining the anti-tilting mounting of the rotor base body.

[0006] This object is achieved according to the features of the invention.

[0007] In the newly designed peristaltic pump, two sliding bearings are provided as described above in order to withstand radial forces and tilting moments. However, these sliding bearings are designed so that they are fixed on both sides of the freewheel by the geometry of the finished driving sleeve. This results in a special advantage, namely that the high requirements for precise manufacturing are limited to the knurled sleeve and the supporting ring accommodated therein, if necessary, in order to ensure the coaxiality between the freewheel and the bearing. In contrast, the rotor base can be manufactured with larger tolerances, which significantly reduces the manufacturing costs. In addition, this design also provides the possibility of keeping the structural space for the design of the bearings and the transmission of torque as small as possible.

[0008] According to an advantageous design, one bearing point is formed by a cylindrical inner surface section of the edge side of the driver sleeve, and the other bearing point is formed by a bearing ring inserted into the driver sleeve with an interference fit. In this way, the bearing points can be arranged at a large axial distance, so that radial forces and tilting moments can also be absorbed with components that require a reduced installation space, such as a drive shaft.

[0009] If the driver sleeve has a continuous, ie common, mating surface for the pressed-in freewheel and the bearing ring, production is further simplified while ensuring a highly precise coaxial alignment of the freewheel and the bearing.

[0010] Another advantageous design is that the driver sleeve is configured with at least a toothed section on the outside, which can be pressed into a central recess of the rotor base body configured with a demoulding chamfer to establish a rotationally fixed positive connection. In this way, the rotor base body can be configured as an injection molded part, wherein the recess in the rotor base body no longer needs to be reprocessed.

[0011] If two axially spaced-apart toothing sections are provided which are situated radially outside the bearing point, the torque can be transmitted particularly uniformly to the rotor base body, whereby the transmittable torque can be further increased at a small overall size.

[0012] In conjunction with the design of the rotor base body as a cast part, the assembly is particularly advantageous if the toothing sections have diameters of different sizes and the central recess of the rotor base body has a plurality of sub-regions with different diameters and demolding bevels. This meets the requirements for a design that is compatible with injection molding. In addition, this simplifies the pressing-in process of the knurled sleeve and optimizes the required demolding bevel angles. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] An exemplary embodiment of the present invention is explained in more detail below with the aid of schematic drawings.

[0014] Figure 1 is a perspective middle cross-sectional view of a rotor of a peristaltic pump according to a first embodiment;

[0015] Figure 2 is based on Figure 1 A perspective cutaway view of a knurled sleeve with a pressed-in freewheel used in a peristaltic pump of;

[0016] Figure 3 is based on Figure 2 A cross-sectional view of a knurled sleeve with a pressed-in freewheel;

[0017] Figure 4 Shown on an enlarged scale for Figure 2 and Figure 3A cross-sectional view of a receiving portion in a rotor base body of a knurled sleeve;

[0018] Figure 5 is a cross-sectional view of the rotor of a peristaltic pump;

[0019] Figure 6 yes Figures 1 to 5 A three-dimensional intermediate cross-sectional view of the rotor base of the peristaltic pump shown in ;

[0020] Figure 7 is a sectional view of a variant design of a knurled sleeve engaging into a rotor base body with a pressed-in freewheel;

[0021] Figure 8 is a schematic cross-sectional view of a pump according to the prior art;

[0022] Fig. 9 is a schematic partial section of a known rotor base body with a pressed-in freewheel; and

[0023] Fig.10 is based on Fig. 9 Cross-sectional view of the knurled sleeve and support ring used in the pump.

[0024] Among them: A-axis line; 20-sleeve freewheel; 25-freewheel rolling element; 30-knurled sleeve; 35A, B-knurling; 36-annular groove; 37-inner shoulder; 38-jointing mating surface; 39-supporting ring; 40-rotor base; 42-accommodation; 42A, B, C-sub-areas of the accommodation portion 42; 44-stop shoulder; 45-rotor cover; 46-extrusion element; 50A, B-sliding bearing part; 120-freewheel; 130-knurled sleeve; 135A, B-knurling; 139-supporting ring; 310-drive shaft; 320-freewheel; 330-knurled sleeve; 340-rotor base; 350-supporting part; 420-sleeve freewheel; 430-knurled sleeve; 435-knurling; 450A, B-sliding bearing part; 470-supporting ring. DETAILED DESCRIPTION

[0025] Figure 1 The rotor 10 of a peristaltic pump is shown in a center sectional view, which can be used in an apparatus for extracorporeal blood treatment, in particular in a dialysis machine. The peristaltic pump has a pump housing (not shown in more detail) in which a rotor rotatable about a rotor axis A is accommodated, which has at least two displacement elements 46 offset relative to one another in the circumferential direction (see Figure 5 ), the extrusion element is in accordance with Figures 1 to 6The pump housing has a support surface which extends in an arc shape around the rotor axis A and is radially spaced apart from the rotor, and is arranged to support a hose segment which can be radially introduced between the rotor and the support surface.

[0026] In the exemplary embodiment shown, the peristaltic pump has a drive shaft (not shown) with an axis of rotation A, by means of which a rotor base body 40 can be driven, which carries a rotor cover 45. The torque of the drive shaft is transmitted via the sleeve freewheel 20 (see Figure 2 and 3 ) is transferred to the rotor base body 40. For this purpose, a toothed driving sleeve (hereinafter referred to as a knurled sleeve 30 (see Figure 2 ), into which the sleeve freewheel 20 with the freewheel rolling bodies 25 is pressed. The freewheel is provided for manual insertion and removal of the pump segments and manual return of blood without having to open the locking portion. The sleeve freewheel is a freewheel without rolling bearings and is therefore a type of friction coupling with which only torque can be transmitted.

[0027] The knurled sleeve 30 itself is as follows Figure 1 and 5 It can be seen that it is pressed into the base body 40 of the rotor and, more specifically, into the central receptacle 42 having the stop shoulder 44 ( Figure 6 ). For a rotationally fixed connection to the rotor base body 40, the knurled sleeve 30 has two straight knurls 35A and 35B, which are each formed on an axial end section of the knurled sleeve 30. In the illustrated embodiment, the knurl 35A has different outer diameters D35A and D35B. A flat annular groove 36 is located between the knurls 35A and 35B.

[0028] In order to absorb radial forces and tilting moments, sliding bearings 50A and 50B are provided on both sides of the sleeve freewheel 20. The sliding bearing 50A is formed by the cylindrical annular surface of the inner shoulder 37 at the end of the knurled sleeve 30. The other sliding bearing 50B is formed by the running surface of the support ring 39 pressed into the knurled sleeve 30. In this way, the sliding bearings 50A and 50B and their relative positions on both sides of the freewheel 20 are determined by the geometry of the finished knurled sleeve 30. Since the freewheel 20 is pressed into the mating surface of the knurled sleeve 30 anyway, the required coaxiality between the bearings 50A, 50B and the freewheel 20 can be ensured simply by the production of the knurled sleeve 30. In other words, only the manufacturing accuracy of the knurled sleeve 30 and the bearing ring 39 determines the coaxiality of the bearing of the freewheel 20 and the rotor base body 40, so that the rotor base body 40 can be manufactured with greater tolerances, thereby significantly reducing the manufacturing costs. In addition, this design also provides the possibility of keeping the structural space for the design of the bearing point and the torque transmission as small as possible.

[0029] Depend on Figure 3 It can be seen that the support ring 39 is pressed into the cylindrical engagement surface 38, which at the same time forms the engagement surface for the sleeve freewheel 20. This further simplifies production.

[0030] Since the rotor base body 40 can be manufactured with greater tolerances due to the above-described arrangement of the sleeve freewheel 20 and the sliding bearings 50A and 50B, it can be designed as an injection molded part, for example as a metal or preferably glass fiber reinforced plastic injection molded part, without further processing. The design of the knurling 35A and 35B differs as follows:

[0031] Since the knurl 35A has a larger outer diameter than the knurl 35B, the receptacle 42 for the knurled sleeve 30 can be formed in the base body (e.g., in Figure 4 ) is divided into a plurality of sub-areas 42A to 42C with different diameters and demolding bevels. The sub-areas 42A and 42C are constructed to be slightly conical, for example with a cone angle of 1.5°. These sub-areas 42A and 42C are adapted to the associated knurls 35A and 35B in terms of their diameter and in terms of their axial extension, so that when the knurled sleeve 30 is pressed in, with its straight knurled parts 35A and 35B and the resulting material displacement, a uniform and firm meshing occurs between the knurled sleeve and the rotor base body 40, so that the torque introduced by the rotor shaft can be distributed as uniformly as possible on the rotor base body 40 over the entire structural height of the rotor base body 40. This is because the form-locking connection between the knurled sleeve 30 and the rotor base body 40 is located essentially radially outside the bearing locations 50A and 50B. The sub-area 42B located between the sub-areas 42A and 42C is constructed as a demolding bevel with a slightly larger cone angle of 2°.

[0032] In the above-described embodiment, the arrangement is such that the knurled sleeve 30 carries the bearing ring 39 on the side provided with the knurls 35B having the smaller diameter D35B. The bearing site 50A facing the rotor cover 45 is formed by the knurled sleeve 30 . Figure 7 A modified design of the mounting unit is shown. In this figure, components corresponding to those of the previous embodiment are provided with similar reference numerals preceded by a "1".

[0033] Here, the inner shoulder 137 of the knurled sleeve 130 is formed on the side where the knurling 135B with a smaller diameter is formed. The support ring 139 is pressed into the engagement surface of the knurled sleeve 130 on the other side, namely radially inside the knurling 135A with a larger diameter. The receptacle 142 formed in the rotor base body corresponds to the knurling 135B according to Figures 1 to 6 The receiving portion 42 of the embodiment.

[0034] Therefore, the present invention provides a peristaltic pump, in particular for conveying fluids in an apparatus for extracorporeal blood treatment, having a pump housing, in which a rotor rotatable about a rotor axis is accommodated, the rotor having at least two extrusion elements offset from each other in the circumferential direction. The pump housing has a support surface extending in an arc around the rotor axis and radially spaced apart from the rotor, the support surface being arranged to support a hose segment that can be radially introduced between the rotor and the support surface. The rotor is driven by means of a rotor shaft, the rotational movement of which can be transmitted to the rotor base body via a freewheel pressed into a toothed driving sleeve, and sliding bearing portions for the base body are arranged on both sides of the freewheel. In order to ensure the coaxiality between the freewheel and the anti-tilting bearing of the rotor base body at low manufacturing costs, the sliding bearing portions are determined on both sides of the freewheel by the geometry of the finished driving sleeve.

Claims

1. A peristaltic pump, in particular for conveying fluid in an apparatus for extracorporeal blood treatment, the peristaltic pump having A pump housing, in which a rotor (40, 45) rotatable about a rotor axis (A) is accommodated, the rotor having at least two extrusion elements (46) offset from one another in the circumferential direction, and the pump housing having a support surface extending in an arc shape about the rotor axis (A) and radially spaced from the rotor, the support surface being provided for supporting a hose segment which can be radially introduced between the rotor and the support surface, in, The rotor (40, 45) is driven by means of a rotor shaft, the rotational movement of the rotor shaft can be transmitted to the rotor base (40) via a free wheel (20) pressed into a toothed driving sleeve (30), and sliding bearing parts (50A, 50B) for the rotor base (40) are provided on both sides of the free wheel (20), characterized in that the sliding bearing parts (50A, 50B) are fixed on both sides of the free wheel (20) by the geometry of the finished driving sleeve (30).

2. The peristaltic pump according to claim 1, It is characterized in that One bearing location (50A; 150B) is formed by an edge-side, cylindrical inner surface section of the driving sleeve (30; 130), and the other bearing location (50B; 150A) is formed by a bearing ring (39; 139) inserted into the driving sleeve (30; 130) with an interference fit.

3. The peristaltic pump according to claim 2, It is characterized in that The driver sleeve (30) has a continuous mating surface (38) for the pressed-in freewheel (20) and the support ring (39).

4. A peristaltic pump according to any one of claims 1 to 3, It is characterized in that The driver sleeve (30) has at least one toothing section (35A, 35B) on the outside, which can be pressed into a central recess (42) of the rotor base body (40) to produce a rotationally fixed positive connection.

5. The peristaltic pump according to claim 4, It is characterized in that Two axially spaced-apart toothing sections (35A, 35B; 135A, 135B) are provided which are located radially outside the bearing point (50A, 50B; 150A, 150B).

6. The peristaltic pump according to claim 5, It is characterized in that The toothed sections (35A, 35B; 135A, 135B) have diameters (D35A, D35B) of different sizes, and a central recess (42) of the rotor base body (40) has a plurality of sub-areas (42A, 42B, 42C) having different diameters and demolding bevels.

7. The peristaltic pump according to claim 6, It is characterized in that The sub-regions (42A, 42B, 42C) of the central recess (42) are each designed conically with cone openings pointing in the same direction.

8. The peristaltic pump according to claim 7, It is characterized in that The cone angle of the sub-regions (42A, 42C) that accommodate the toothing sections (35A, 35B; 135A, 135B) is smaller than the cone angle of the sub-region (42B) located therebetween.

9. A peristaltic pump according to any one of claims 1 to 8, It is characterized in that The rotor base body (40) is designed as an injection-molded part, preferably made of glass-fiber-reinforced plastic or light metal.

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