Coalescence separator, in particular for use in a crankcase ventilation system, crankcase ventilation system and use of coalescence separator

Abstract

A coalescence separator for separating liquid droplets from a gas flow has a gas inlet and a gas outlet. A multi-layer structure of a plurality of individual layers of a coalescence filter medium is arranged between the gas inlet and the gas outlet, wherein the coalescence filter medium is provided with a glass fiber paper with glass fibers. The individual layers of the coalescence filter medium each have an individual layer thickness of more than 0.8 mm and maximally 5 mm, a grammage of greater than 80 g/m.sup.2 and less than 500 g/m.sup.2, and an air permeability of 350 l/m.sup.2s to 1,800 l/m.sup.2s. The multi-layer structure has between 2 and 80 of the individual layers.

Claims

1. A coalescence separator for separating liquid droplets from a gas flow, the coalescence separator comprising: a gas inlet; a gas outlet; a multi-layer structure comprising a plurality of individual layers of a coalescence filter medium and arranged between the gas inlet and the gas outlet, wherein the coalescence filter medium comprises a glass fiber paper with glass fibers; wherein the individual layers of the coalescence filter medium each have an individual layer thickness of more than 0.8 mm and maximally 5 mm, a grammage of greater than 80 g/m.sup.2 and less than 500 g/m.sup.2, and an air permeability of 350 l/m.sup.2s to 1,800 l/m.sup.2s; wherein a mass proportion of incinerable materials contained in the coalescence filter medium amounts to maximally 10%.

2. The coalescence separator according to claim 1, wherein the multi-layer structure comprises between 2 and 80 of the individual layers.

3. The coalescence separator according to claim 2, wherein the individual layers are immediately arranged on each other and are either stacked or coiled.

4. The coalescence separator according to claim 1, wherein the coalescence filter medium is a single layer structure.

5. The coalescence separator according to claim 4, wherein the single layer structure is homogenous.

6. The coalescence separator according to claim 1, wherein a total grammage of the multi-layer structure, calculated by multiplying the grammage of the individual layers by the number of the individual layers, is between 500 g/m.sup.2 and 8,000 g/m.sup.2.

7. The coalescence separator according to claim 1, wherein a total air permeability of the multi-layer structure having the plurality of individual layers of a coalescence filter medium is between 15 l/m.sup.2s and 350 l/m.sup.2s.

8. The coalescence separator according to claim 1, wherein a product of the air permeability of the individual layers multiplied by the grammage of the individual layers amounts to between 110 g/m*s and 220 g/m*s.

9. The coalescence separator according to claim 1, wherein a mass proportion of the glass fibers of the glass fiber paper of the coalescence filter medium amounts to at least 90%.

10. The coalescence separator according to claim 1, wherein the coalescence filter medium comprises a binder with a mass proportion of maximally 10%.

11. The coalescence separator according to claim 10, wherein the binder contained in the coalescence filter medium contains no bi-component fibers or melt fibers.

12. The coalescence separator according to claim 10, wherein the binder contained in the coalescence filter medium is an acrylate binder.

13. The coalescence separator according to claim 1, wherein the grammage of the individual layers is greater than 100 g/m.sup.2.

14. The coalescence separator according to claim 1, wherein the air permeability of the individual layers is greater than 600 l/m.sup.2s.

15. The coalescence separator according to claim 1, wherein at least 90% of the glass fibers of the glass fiber paper of the coalescence filter medium have a fiber diameter of greater than 2.5 μm.

16. The coalescence separator according to claim 1, wherein at least 90% of the glass fibers of the glass fiber paper of the coalescence filter medium have a fiber diameter of less than 10 μm.

17. The coalescence separator according to claim 1, wherein the glass fibers of the glass fiber paper of the coalescence filter medium have an average fiber diameter of between 4 μm and 6 μm.

18. The coalescence separator according to claim 1, wherein a finest separation stage of the coalescence separator is formed by the multi-layer structure.

19. The coalescence separator according to claim 1, wherein a finest separation stage of the coalescence separator is formed by the coalescence filter medium.

20. The coalescence separator according to claim 1, wherein a finest separation stage of the coalescence separator is formed by the multi-layer structure and the coalescence filter medium.

21. The coalescence separator according to claim 1, wherein the multi-layer structure forms a separating stage of the coalescence separator that determines an efficiency of the coalescence separator.

22. The coalescence separator according to claim 1, wherein the coalescence filter medium forms a separating stage of the coalescence separator that determines an efficiency of the coalescence separator.

23. The coalescence separator according to claim 1, wherein the multi-layer structure and the coalescence filter medium form a separating stage of the coalescence separator that determines an efficiency of the coalescence separator.

24. The coalescence separator according to claim 1, wherein the multi-layer structure comprises two or more differently configured ones of the individual layers of the coalescence filter medium.

25. A crankcase venting system comprising a coalescence separator according to claim 1.

26. The crankcase venting system according to claim 25, wherein the crankcase venting system is a closed crankcase venting system of an internal combustion engine and the coalescence separator has no further fine separator or further fine separation layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) As already explained above, there are various possibilities to configure and further develop the teachings of the present invention in an advantageous way. In this regard, on the one hand, reference is being had to the claims that depend from the independent claim; on the other hand, further embodiments, features, and advantages of the present invention will be explained in more detail in the following inter alia with the aid of the embodiment illustrated by FIGS. 1 to 3 as well as with further examples.

(2) FIG. 1 shows in perspective illustration an embodiment of a crankcase venting (CCV) system with a coalescence separator according to the present invention.

(3) FIG. 2 shows in longitudinal section illustration the crankcase venting (CCV) system of FIG. 1.

(4) FIG. 3 shows in longitudinal section illustration a detail view of the coalescence separator of FIG. 2.

(5) FIG. 4 shows in section illustration a detail view of a further coalescence separator.

DESCRIPTION OF PREFERRED EMBODIMENTS

(6) FIG. 1 shows in a perspective view a crankcase 410 that is only schematically indicated and that comprises a coalescence separator 200 of a crankcase venting (CCV) system. The crankcase 410 is a component of an internal combustion engine. The internal combustion engine can be installed in a motor vehicle. The coalescence separator 200 is configured as a coalescence separator for oil-containing air from an interior of the crankcase 410. The oil-containing air in such applications is usually contaminated with combustion gases which leak from the cylinders as leakage gas into the crankcase. This mixture is regularly also referred to as crankcase gas wherein presently the term air will be used in the following for simplification.

(7) The coalescence separator 200 comprises a substantially oval cylindrical, in particular circular cylindrical, housing which is comprised of a first housing part 210, namely a housing cover, and a second housing part 220, namely a housing body. The second housing part 220 comprises an inlet 222 for the oil-containing air 500. In the housing, an in particular exchangeably insertable separating element 100 is arranged which comprises at least a multi-layer structure 10 of spirally shaped coalescence filter medium wound in multiple layers; see FIG. 2. In other embodiments, a stack is conceivable. The separating element 100 is hidden in FIG. 1 by the housing and therefore provided with a dashed reference character line. Within the housing 210, 220, the air 500 (a corresponding air flow 20 is indicated in FIG. 3 by an arrow) is purified by means of the multi-layer structure 10 of the coalescence filter medium. The resulting clean air 510 is guided from an interior 12 (FIG. 2) enclosed by the multi-layer structure 10 via a clean air discharge element 50 of the separator element 100 to a clean air outlet 212 of the housing cover 210 and from the clean air outlet 212 back into the intake manifold of the internal combustion engine. Separated oil is discharged via an oil outlet 230.

(8) In order to limit the crankcase vacuum to a defined value, the coalescence separator 200 comprises a pressure regulating valve. The pressure regulating valve, which is illustrated, for example, in FIGS. 2 and 3, has a valve closure body 310 which is surrounded by a valve closure body sealing element 320, preferably by a membrane, as illustrated here. Such valves are combinable also with the coalescence separator 200 which is shown schematically in FIG. 4 and described in the following.

(9) The coalescence separator 200 comprises a preferably openable housing which is comprised of a first housing part 2100, namely a housing cover, and a second housing part 2200, namely a housing body. The second housing part 2200 comprises an inlet 2220 for the oil-containing air 500. In the housing, an in particular exchangeably insertable separating element 1000 is arranged which comprises at least a multi-layer structure 10 of coalescence filter medium stacked in multiple layers, a seal 2400 which is clamped seal-tightly between the housing parts 2100, 2200, and a support frame 2300 that is fixedly connected to the seal 2400 and the multi-layer structure 10. In other embodiments, a coil is conceivable. Within the housing 2100, 2200, the air 500 (a corresponding air flow 20 is indicated by an arrow) is purified by means of the multi-layer structure 10 of the coalescence filter medium. The resulting clean air 510 is guided from a clean room which is arranged in FIG. 4 to the left of the separating element 1000 via the clean air outlet 2120 of the housing cover 2100 back into the intake manifold of the internal combustion engine. Separated oil is discharged via an oil outlet 2300.

EXAMPLES

(10) Embodiments of a coalescence separator according to the invention have been compared with three different other structures. In this context, different coalescence filter media have been employed. Separation degrees have been determined based on an aerosol with a volume-weighted average drop size of appr. 1.1 μm. The examples have been configured with respect to the respective number of layers with the goal that the pressure loss is within the range of 20 mbar for appr. 20 cm/s inflow speed. In this context, it is clearly apparent that the comparative examples comprise a comparatively minimal product of grammage and air permeability and a minimal performance capability in relation to the ratio pressure loss and separation degree. This is referred to often by factor of quality (quality factor) which is calculated as follows:
Q.sub.f=ln(1/P)/delta P,
wherein P=penetration=(1-separation degree) and wherein deltaP=pressure difference.

(11) TABLE-US-00001 product air thickness grammage * air coalescence grammage permeability mm @ permeability filter medium g/m.sup.2 l/m.sup.2s 10 kPA g/(m*s) Examples example 1 glass fiber 108 1632 1.14 176 paper with appr. 95% glass fibers example 2 glass fiber 220 723 1.96 159 paper with appr. 95% glass fibers comparative examples comparative glass fiber 71 672 0.7 48 example 1 paper with appr. 95% glass fibers comparative glass fiber 65 1212 0.56 79 example 2 paper with appr. 95% glass fibers comparative glass fiber 75 817 0.64 61 example 3 paper with appr. 95% glass fibers separation pressure quality number of fibers degree difference factor less than 3 μm layers % mbar 1/kPa examples example 1 <10% 5 86.2 17.8 1.11 example 2 <10% 6 92 19.3 1.31 comparative examples comparative appr. 30% 4 87.1 23.8 0.86 example 1 comparative appr. 30% 4 85.1 24.8 0.76 example 2 comparative appr. 30% 13 89.2 25.6 0.87 example 3

(12) Examples 1 and 2 are in each case coalescence separators according to the invention which are embodied with two different embodiments of a coalescence filter medium that differ substantially in relation to the grammage. Both comprise a glass fiber proportion of 95% wherein the remainder is an incinerable binder mixture. In each case, 90% of the glass fibers of the coalescence filter medium contained in the coalescence filter medium comprise a fiber diameter between 3 μm and 7.5 μm and an average fiber diameter (d50) between 5 μm and 6 μm. It is clearly apparent that in both variants a separation degree of above (example 2) or approximately (example 1) 90% at a pressure loss below 20 mbar is achieved. Correspondingly, in both variants a quality factor of greater 1 is achieved. Example 2 in comparison to example 1 can even be produced somewhat better because the employed embodiment of the coalescence filter medium is less sensitive in regard to processing. In this respect and in particular in regard to the processing of glass fiber papers with a high glass fiber proportion as in the present examples of above 90% of the total weight, the use of coalescence filter media with a grammage of above 150 g/m.sup.2, preferably above 180 g/m.sup.2, can enable a good processing reliability and thus a fast manufacture. In an individual case, it can be advantageous for the production of a multi-layer structure according to the invention in mass production environments, in particular when producing coiled embodiments, to provide the coalescing filter medium with a carrier layer that is not separation-effective. In this way, the coalescence filter medium can be exposed to higher tensile forces and speeds during production. The carrier layer can be attached by lamination and should be, in particular so as to not significantly affect the homogeneity of the separation structure across the multi-layer structure, significantly thinner (at least four times thinner, preferably with a thickness of less than 0.25 mm) and more permeable (at least three times more permeable, preferably minimum air permeability 5,000 l/m.sup.2s) in comparison to the glass fiber paper. For this purpose, for example, a thin spun nonwoven with appr. 0.2 mm thickness and with high air permeability of, for example, appr. 6,500 l/m.sup.2s can be employed. Preferred are however carrier layer-free coalescence filter media.

(13) Even though the comparative examples show an air permeability in a similar magnitude as the aforementioned examples, they have a reduced product of grammage and air permeability. It is moreover clearly apparent that already for minimal number of layers (comparative examples 1 and 2) a differential pressure of greater than 20 mbar is produced and no separation degree of 90% is achieved. In comparative example 3, a separation degree of almost 90% is indeed achieved but at the expense of the pressure loss which is above 25 mbar in this comparative example 3. In comparison to the aforementioned examples, all have a significantly reduced quality factor of below 0.9 in common.

(14) Based on this, it is apparent from the comparison that a fine fiber proportion of significantly less than 30%, more precisely a comparatively minimal proportion of fibers with a diameter of less than 3 μm, can contribute significantly to reaching a structure optimized with regard to separation degree and pressure loss. The effect, as demonstrated, is clearly apparent for a proportion of less than 10% but a significant improvement is to be expected even for a proportion of less than 20%.