EP2161453A2 - Rotor set and rotor pump - Google Patents

Abstract

The rotor set has a rotor housing (1) with a medium inlet and a medium outlet, comprising an external rotor (2) and an inner rotor (3) made of an elastic material, particularly plastic or polymer material. The external rotor is a uniformly corrugated ring of constant wall thickness (s-1) with rounded recesses and convexities (8,12), which are spring elements acting in the linear elastic area.

Description

The invention relates to a rotor set for a pump or a compressor, preferably for a gerotor pump with a rotor housing having a media inlet and a media outlet, consisting of an outer rotor and an inner rotor made of an elastic material, in particular plastic. The invention further relates to a rotor pump with a rotor set executed according to the invention.

Rotor pumps are positive displacement pumps for liquid, gaseous or solid substances, for example gerotor pumps or internal gear pumps, and are used, for example, in automotive engineering as media feed pumps or compressors. Both in the Innenzahnrad- and the gerotor pump driven via a drive shaft rotor eccentrically in an inner toothing of an outer rotor. In the case of the ring gear pump, the medium is conveyed through the displacement volume which varies in its volume between the tooth spaces of the toothings of the inner rotor and the outer rotor. In the internal gear pump, the medium to be delivered is conveyed in the spaces between the tooth spaces of the teeth of the inner and outer rotor, wherein the teeth are sealed by a sickle. Both designs differ in the size ratios of the teeth on the inner and outer rotor. While the outer rotor of a gerotor pump has exactly one more tooth than the inner rotor and is usually provided with a particularly straight-toothed trochoidal, polygonal or other toothed form, the internal gear pump on the outer rotor has significantly more teeth than the inner rotor.

From the WO-A 00/70228 is a toothed rotor set for a pump, in particular for a lubricating oil pump for internal combustion engines, known. The gear rotor is similarly executed to the rotors of a gerotor pump, so that its function and mode of operation corresponds to the function and operation of a gerotor pump. The toothing of at least one of the two rotors has an arcuate portion at least in partial regions of the respective toothing. Due to the arcuate portion of the toothed shape should essentially roll friction and no sliding friction occur to minimize wear on the teeth. From the DE-C-42 14 752 an internal gear pump serving as an engine oil pump for internal combustion engines is known, which has a housing having a receiving part made of plastic with a recess for receiving two mutually in drive engagement pump rotors and a cover covering the recess. The two pump rotors are made of polyphenylene sulfide or polyethersulfone with high abrasion resistance, wherein the polyphenylene sulfide carbon fiber reinforced plastics are mixed. The receiving part is at those surfaces which are in frictional engagement with the pump rotors, from the other of these plastics. Such a pump designed to have a long life with low weight.

From the DE-A-100 06 629 is a gear made of plastic for a gear pump known, wherein the wheel body of the gear has an external or internal toothing, the teeth have at least one at least accessible from a tooth face cavity. The cavities are closed at the front or filled with a temperature and media-resistant filler with low specific weight. In the from the DE-U-299 03 512 Known gear for a gear pump is proposed to reduce the weight of the pump rotors to provide the tooth interior with an intermediate wall, through which this is divided into two substantially equal sized, mutually connection-free depressions.

In all known systems of inner and outer rotors for gear or rotor pumps, it is customary to either perform the outer rotor made of solid material or locally provided with recesses or holes and the inner rotor, depending on the material, either locally provided with holes or openings or also made of solid material. The known designs are subject to a number of disadvantages. External rotors made of solid material have a certain Construction volume and thus a higher weight. Since the known outer rotors lie flat against the inner wall of the rotor housing, high frictional forces arise between the outer rotor and the rotor housing. An outer rotor made of solid material allows only a certain displacement volume and thus limits the pump performance. By occurring after a certain period of operation of the pump wear it also leads to power losses and leakage rates. The known rotors can also be made only with small component tolerances due to the present geometric specifications and designs, which requires high production costs and optionally a post-processing of the finished components, especially in nano and micropumps. These not to be observed small tolerances in the previously known constructions lead both in the rotor set assembly and in pump or compressor operation to some extent not yet solved problems that are to be solved with the present invention.

The invention is therefore based on the object to execute a set of rotors so that it does not identify the mentioned disadvantages of the known designs, in particular allows a larger displacement volume or allows a smaller design, despite any wear no or hardly any power losses and hardly causes leakage rates and low costs can be produced.

The object is achieved according to the invention in that the outer rotor is a uniformly wavy ring of constant wall thickness with rounded executed lobes and bulges, which are acting in the linear elastic region spring elements.

Due to the structural design of the outer rotor as a ring-like, elastically resilient component, the displacer volume can be significantly larger than in the known outer rotors, whereby a higher pump performance can be achieved. With the same pump capacity, the outer rotor according to the invention can be made smaller, with a smaller outer diameter, its space requirement is thus lower, which is crucial especially in micropumps. The outer rotor ring is only in the region of its bulges and thus only in places in contact with the rotor housing, which reduces its wear on the material. Of particular importance, however, is the design of the outer rotor as a spring. This allows the occurring Wear of the outer rotor over the life of the pump are compensated, which over their entire life, the leakage rates are very small. Finally, the production costs of an outer rotor designed according to the invention are substantially lower than those of conventionally designed outer rotors.

For a low wear of the outer rotor, it is advantageous if the bulges of the outer rotor are rounded in such a way that they provide substantially linear contact points for the rotor housing.

To optimize the spring action of the outer rotor, it is advantageous if the indentations of the outer rotor occupy larger ring segments than the bulges.

The design of the inner rotor is also of particular importance. An outer rotor designed according to the invention can be combined in a particularly advantageous manner with an inner rotor, which has spring elements acting on its outer circumference in the linear elastic region, which contact the indentations of the outer rotor. These spring elements take over the function of the outer teeth conventionally designed inner rotors, with the additional effect that the pump working pressure pushes the spring elements during the entire period of use of the pump of up to 5000 hours to the outer rotor and through this to the inner wall of the rotor housing, which optimally compensates for wear the leakage rates are reduced and thus the pump performance is optimized.

In a preferred embodiment of the invention, the spring elements of the inner rotor are designed in the form of curved wings. The wing shape ensures a very large displacement volume and thus a higher pump performance and, alternatively, allows very small designs, for example for micropumps.

In order to avoid the occurrence of tension and thus have to accept no loss of quality, the inner rotor is made such that the wings and his other parts have at least substantially or largely constant and matching wall thicknesses.

It is advantageous if the wings have over their zenith extending, bent end portions. The wing tips are therefore designed so that there are only linear contact points with the outer rotor and can not catch the protruding round wing tips with the outer rotor.

In another embodiment of the inner rotor, this outer teeth coming into contact with the indentations of the outer rotor, each having at least one recess which is arranged such that the inner rotor is formed of material webs with at least substantially constant and matching wall thicknesses. This version is especially suitable for high-pressure pumps, whereby here too the concept of equal wall thicknesses is given.

• Fig. 1 eine Ausführungsform eines Rotorensatzes für eine Zahnringpumpe, insbesondere eine Hochdruckpumpe bis etwa 80 bar,
• Fig. 2 eine weitere Ausführungsform eines Rotorensatzes für eine Zahnringpumpe, insbesondere eine Niederdruckpumpe bis etwa 30 bar, und
• Fig. 3 eine Variante eines Außenrotors.

Further features, advantages and details of the invention will now be described with reference to the schematic drawing illustrating exemplary embodiments. Show

• Fig. 1 an embodiment of a rotor set for a gerotor pump, in particular a high-pressure pump up to about 80 bar,
• Fig. 2 a further embodiment of a rotor set for a gerotor pump, in particular a low pressure pump to about 30 bar, and
• Fig. 3 a variant of an outer rotor.

The invention is concerned with a special embodiments of outer and inner rotors of elastic materials, in particular plastics, for rotor pumps, in particular gerotor pumps, or compressors.

Fig. 1 shows a rotor housing 1, which has a bearing opening, not shown, for receiving a drive shaft, also not shown, which with a Inner rotor 3, which has a central opening 4 for receiving the drive shaft, firmly connected or firmly connected. In Fig. 1 an inlet opening 9 is indicated on the suction side, which is formed for example laterally as a bore in the rotor housing 1, on the pressure side opens analogous to an outlet opening 10 a. The provided with external teeth 7 inner rotor 3 is positioned within an outer rotor 2, which, as will be described in more detail, cooperates with the outer teeth 7 of the inner rotor 3. The axis of rotation of the outer rotor 2 coincides with the central axis of the rotor housing 1, the axis of rotation of the inner rotor 3 is offset eccentrically with respect to the axis of the outer rotor 2 by a distance a.

The four outer teeth 7 of the inner rotor 3 are uniformly distributed over the outer circumference of the inner rotor 3 and made coincident.

The outer teeth 7 of the inner rotor 3 are each provided with a number of recesses 15, which are designed and arranged so that they form material webs 16 between them and to the outer edges of the inner rotor 3, which have constant and matching wall thicknesses s ₂ .

According to the invention, the outer rotor 2 is a regularly corrugated ring with a constant wall thickness s ₁ , where s ₁ may coincide with s ₂ . The ring 2 is therefore composed of rounded indentations 8 and rounded bulges 12, wherein the indentations 8 occupy larger ring segments than the bulges 12. The "amplitudes" of the indentations and bulges preferably match. The inner contour of the bulges 12 coincides with the outer contour of the tip regions of the outer teeth 7 of the inner rotor 2. The present on the outside of the outer rotor 2, rounded bulges 12 are designed such that they come into contact only via line-shaped contact points 14 with the inner surface 1 b of the rotor housing 1. The line-shaped contact points 14 are above all for a low wear of the outer rotor 2 of advantage.

The recesses 8 which are uniformly arranged over the circumference of the outer rotor 2 and which are comparable in function to the inner teeth of conventionally designed outer rotors are in contact with the outer teeth 7 of the Inner rotor 3. During operation of the pump, the inner rotor 3, which is rotated by the drive shaft, drives the outer rotor 2. The number of teeth 7 of the inner rotor 2 is one less than the number of indentations 8 of the outer rotor 2, wherein the inner rotor 3 between three and ten, preferably four, as shown, or five teeth 7 has.

The elastic material used for the outer rotor 2 causes the outer rotor 2 acts as a spring in the linear elastic range, the recesses and bulges 8, 12 act as spring elements. Thus, the outer rotor 2 is able to compensate for manufacturing tolerances that may affect the outer rotor 2 itself, the inner rotor 3 or the rotor housing 1. Of particular importance, however, that any occurring wear of the outer rotor over the life of the pump can be compensated by the spring action, which over its entire life, the leakage rates are very small.

Namely, by its spring elements, the outer rotor 2 is constantly pressed against the inner surface 1b of the rotor housing 1 via the working pressure prevailing during operation of the pump with a high contact pressure. This ensures that any wear of the outer rotor 2 is compensated and no or only very small leakage rates occur. In the usual manufacturing tolerances also unproblematic installation is guaranteed. The inner rotor 3 can have a small excess tolerance, without the installation of the two rotors 2, 3 is impaired, since the spring system of the outer rotor 2 tolerances within certain limits can compensate well without the function of the pump is impaired. In this context, it is essential that the outer rotor 2, preferably also the inner rotor 3, according to the concept of constant wall thicknesses s ₁ , s _{2 are} executed. Outer and inner rotor 2, 3 can also be easily designed so that the displacement volume and thus the pump capacity (flow rate) are as high as possible.

A particularly high pump performance can be achieved with the in Fig. 2 achieved rotor set. The execution of the outer rotor 2 corresponds to that according to Fig. 1 , The inner rotor 3 'has evenly distributed over its circumference arranged and matching executed wings 17. Each wing 17 forms a linear elastic region acting spring element. Between the wings 17 run webs 18, which follow the contour of the central opening 4 'and have the material thickness s ₂ . In the attachment area 19 of the wings 17, a recess 20 ensures a substantial presence of the material thickness s ₂ . The wings 17 themselves also have the material thickness s ₂ over a large part of their extent. The free wing tips are rounded and bent back over their zenith and have a decreasing to zero material thickness. In the area of these curves, the wings 17 come into contact with the recesses 8 of the outer rotor 2. The wings 17 reduce the volume of the inner rotor 3 drastically, so that the displacement volume and thus the pump performance by up to 35% - compared to a conventional design of the inner rotor with " Teeth "- can be increased. Alternatively, by such a design of the inner rotor 3 ', the installation space can be reduced by up to 35% at approximately the same high power. The one-sided, in particular in the media conveying direction open wings 17 of the inner rotor 3 'are particularly designed so that a working pressure between 0.01 bar and 25 bar, the wings 17 of the inner rotor 3' with at least 0.5 N / mm ² and at most 100 N / mm ² to the outer rotor 2 presses.

Suitable materials for the outer rotor 2 and the inner rotor 3 and 3 'are polymer materials such as PA, POM. LCP, PEEK, PAI. PPA PAI, PPS or other polymer materials with high abrasion resistance, wherein the polymer materials (plastics) friction and wear-optimizing fillers such as graphite, PTFE, MoS2, aramid fibers, carbon fibers or nanocrystals can be mixed. Polymers whose elastic modulus is between 5000 N / mm ² and 80 000 N / mm ² are suitable. The elongations at break in the linear elastic range must be greater than 0.5%, but less than 10%. The linear elastic stress-strain range must not be exceeded in the stress during operation, so that the respective material can relax and a long-term use is guaranteed.

It is also advantageous to equip the materials for the outer rotor 2 and the inner rotor 3, 3 'by appropriate fillers friction and wear optimized. Additionally or alternatively, the surfaces of the rotors 2, 3, 3 'may be coated with friction and wear-reducing effects. The inner surface 1 b of the rotor housing 1 may be coated accordingly.

Fig. 3 shows a variant of an inventively designed outer rotor 2. The acting as spring elements indentations 8 are each provided in the region of their zenith with an insert 21. The inserts 21 are inserted in the outer rotor 2 so that they come into contact with the outer teeth or wings of the inner rotor, not shown here. The inserts 21 are either made of a friction-reducing material or of a more elastic material than the outer rotor 2. Such inserts 22 may also be inserted in the region of the zenith of the protrusions 12.

The rotors 2, 3, 3 'may have certain manufacturing tolerances that can be compensated by their spring action, the drive power must take into account the resistance of the spring elements of the rotors 2, 3, 3'. In the case of micropumps, positive tolerances of the inner rotor 3, 3 'of up to 0.5 mm are possible, but considerably more in the case of macro-pumps with larger dimensions. Minus tolerances should be excluded, otherwise the performance drops when leaks occur.

The coefficients of friction of the surfaces in contact with each other should be between 0.1 and 0.2 according to VDI 2541, the coefficient of friction should be between 0.5 and 0.75 depending on the speed. The surfaces of the materials in contact with each other should be such that the work of adhesion W is between 35 mN / m and 70 mN / m and the coefficient of friction is not more than 0.2. Any malfunctions such as a pump return are unproblematic for rotors according to the invention. Also, any contamination is not critical, if the size of the dirt particles does not exceed certain dimensions.

LIST OF REFERENCE NUMBERS

1

rotor housing

1a

palm

2

outer rotor

3, 3 '

inner rotor

4, 4 '

opening

7

outdoor gear

8th

indentation

9

inlet port

10

outlet

12

bulge

14

contact line

15

recess

16

material web

17

wing

18

web

19

approach area

20

recess

21

commitment

22

commitment

Claims (15)

Rotor set for a pump or a compressor, preferably for a gerotor pump with a rotor housing (1) with a media inlet and a media outlet, consisting of an outer rotor (2) and an inner rotor (3, 3 ') of an elastic material, in particular plastic,
characterized,
in that the outer rotor (2) is a uniformly corrugated ring of constant wall thickness (s ₁ ) with rounded recesses and protrusions (8, 12) which are spring elements acting in the linear elastic region. Rotor set according to claim 1, characterized in that the bulges (12) of the outer rotor (2) are rounded such that they provide substantially line-shaped contact points (14) for the rotor housing (1) available. Rotors set according to claim 1 or 2, characterized in that the indentations (8) of the outer rotor (2) occupy more ring segments as the bulges (12). Rotor set according to claim 1, characterized in that the inner rotor (3 ') on its outer periphery (3') in the linear elastic region acting spring elements which come into contact with the recesses (8) of the outer rotor (2). Rotor set according to claim 4, characterized in that the spring elements of the inner rotor (3 ') in the form of curved wings (17) are executed. Rotor set according to claim 4 or 5, characterized in that the wings (17) and the other parts of the inner rotor (3 ') at least substantially or substantially constant and matching wall thicknesses (s ₂ ). Rotor set according to one of claims 4 to 6, characterized in that the wings (17) have over their zenith extending, bent end portions. Rotor set according to claim 1, characterized in that the inner rotor (3) with the indentations (8) of the outer rotor (2) in contact outer teeth (7), each having at least one recess (15) which is arranged such that the inner rotor (3) is formed of material webs (16) with at least substantially constant and matching wall thicknesses (s ₂ ). Rotor set according to one of claims 1 to 8, characterized in that the number of external teeth (7, 17) and the wing (17) of the inner rotor (3, 3 ') is between three and ten, preferably four or five. Rotor set according to one of claims 1 to 9, characterized in that the number of indentations (8) of the outer rotor (2) is greater by one than the number of outer teeth (7) and the wings (17) of the inner rotor (3, 3 '). Rotor set according to one of claims 1 to 10, characterized in that the outer and the inner rotor (2, 3, 3 ') consist of a media-resistant polymer material. Rotor set according to one of claims 1 to 11, characterized in that the material of the outer and / or inner rotor (2, 3, 3 ') contains at least one friction or wear-optimizing filler or reinforcing material. Rotor set according to one of claims 1 to 10, characterized in that the outer and / or inner rotor (2, 3, 3 ') are coated friction and / or wear-reducing. Rotor set according to one of claims 1 to 11, characterized in that the indentations and bulges of the outer rotor (2) at their zenith areas each have an insert (21, 22) made of a friction-reducing or an elastically yielding material. Gear pump, in particular gerotor pump, with a rotor set according to one or more of claims 1 to 14.

Images