WO2019007858A1

WO2019007858A1 - Hollow shaft and method for separating a fluid

Info

Publication number: WO2019007858A1
Application number: PCT/EP2018/067698
Authority: WO
Inventors: Ulf MÜLLER; Robert Reichelt
Original assignee: Thyssenkrupp Presta Teccenter Ag; Thyssenkrupp Ag
Priority date: 2017-07-04
Filing date: 2018-06-29
Publication date: 2019-01-10
Also published as: DE102017114909A1; DE102017114909B4

Abstract

The invention relates to a hollow shaft comprising a fluid separation system (11), a gas channel (15) having a gas inlet for the entry of raw gas and a gas outlet for the discharge of purified gas, and a conveying device (12) for conveying a fluid separated from a gas, wherein the conveying device (12) is connected to an inner wall (13) of the hollow shaft (10) in a rotationally fixed manner and comprises a helical guide geometry (14) for conveying the fluid in the longitudinal direction of the hollow shaft (10). The invention further relates to a method for separating a fluid from a gas stream.

Description

Hollow shaft and method for separating a liquid

description

The invention relates to a hollow shaft and a method for separating a liquid.

In internal combustion engines, gases from the working process leak out of the cylinders and accumulate in the crankcase (blow-by gases). Since the crankcase forms a closed space, this would increase the pressure. Therefore, the crankcase is vented by discharging the blowby gases. These contain oil droplets, which are separated from the blowby gas (raw gas) before bleeding the crankcase and fed to the oil circuit. The cleaned gas can then be removed from the crankcase (clean gas).

There are various oil separation systems in the prior art that are known in the art

Internal combustion engines are used.

DE 10 2010 043 060 Al describes, for example, a crankcase with a partition on which oil is separated from the blowby gas. The oil is extracted from the bulkhead by a suction jet pump to improve oil return. The suction jet pump is an expensive solution that requires a large amount of space.

DE 10 2005 003 037 AI discloses a separation device for separating oil from blowby gases. The device has a hollow rotor shaft, on whose outer circumference a screw helix is arranged. The rotor shaft is mounted in a fixed housing in which oily blowby gases are sucked. The oil is deposited on the helix, drops to the bottom of the housing and flows slowly from there due to the effect of gravity. The cleaned gases are discharged through the hollow rotor shaft.

DE 103 21 866 AI describes a similar separation device, wherein a rotor shaft with a spiral screw on the outer circumference in a

fixed housing is rotatably mounted. In order to optimize the separation effect at different flow rates of the gas, the Cross section of the limited by the screw spiral flow channel can be changed. The separated oil runs down the inner wall of the housing due to gravity, is collected at the bottom of the housing and discharged from there.

The invention is based on the object on the one hand to provide a compact device that requires little space and with the from a gas

deposited liquid, such as oil, can be removed.

On the other hand, the liquid removal should be improved. The invention is further based on the object to provide a method for depositing a liquid.

According to the invention the object with a view of the device through the hollow shaft according to claim 1 and with a view to the method by the

Subject of claim 14 solved.

Specifically, the object is achieved by a hollow shaft with a Flüssigkeitsabscheidesystem and a gas channel having a gas inlet for the entry of raw gas and a gas outlet for the discharge of purified gas. The hollow shaft has a conveying device for conveying a liquid deposited from a gas. The conveyor is rotatably connected to an inner wall of the hollow shaft and has a helical guide geometry for conveying the liquid in the longitudinal direction of the hollow shaft.

The invention has the advantage that the integrated into the hollow shaft

Conveyor requires no additional space. The for the

The conveying effect required energy is provided by the rotational movement of the hollow shaft, which is transmitted to the conveyor, since this is rotatably connected to the inner wall of the hollow shaft. The helical

Guide geometry of the conveyor causes by the rotational movement of the hollow shaft, a promotion of the separated liquid in the longitudinal direction of the hollow shaft, so that the liquid is forced to an outlet point for the liquid. This increases the drain rate compared to a gravity based solution. In the case of a cam hollow shaft, the conveying device is preferably arranged at the free end of the shaft so that the conveying device at the outlet point for the liquid increases particularly effectively into the discharge rate. The invention is not limited to such an arrangement.

With the invention, a compact and universally applicable device is provided, which can be used in particular, but not exclusively in connection with a crankcase ventilation. The invention is suitable for systems in which the liquid is collected in a return chamber at the free end of the shaft, wherein the hollow shaft by a dynamic

Radial seal (radial shaft seal RWDR) is sealed. The transport is thereby brought about not only by supporting the gas flow, but by the conveying effect of the conveyor. This has the advantage that a type of "liquid mountain" builds up not only as a function of the viscosity of the respective oil or the liquid at the shaft end, but from which drops break off when the surface tension is exceeded, but rather a substantially continuous outflow through the conveying device the liquid reaches from the hollow shaft, but at least an outflow which is greater than the dripping depending on the respective surface tension of the liquid.The invention can also be used in systems in which the liquid directly, ie without return chamber, in the space to be vented , for example the

Crankcase is returned.

Although a hollow camshaft for internal combustion engines is known from DE 34 90 464 C2, which has a coaxially arranged insert with a spiral screw on the outer circumference, which seals against the inner wall of the camshaft. The worm gear is designed to convey lubricating oil to the bearing points of the camshaft. A passage of gases through the camshaft is provided as well as the separation of oil, which in the

Lubricating oil is not possible.

Preferred embodiments of the invention are specified in the subclaims.

Thus, the guide geometry may comprise at least one coil spring whose turns abut against the inner wall. The adjacent turns form together with the inner wall a conveying channel, which transports the oil adhering to the inner wall or the liquid in the longitudinal direction of the hollow shaft. The coil spring is adapted to the shape of the inner wall and preferably cylindrical. The coil spring is easy to assemble and inexpensive.

In a further preferred embodiment, the guide geometry comprises at least one helical groove which is formed in the inner wall of the hollow shaft. Adhered to the inner wall, deposited liquid is forced through the guided gas flow through the hollow shaft into the groove and there promoted by the rotational movement of the hollow shaft in the longitudinal direction of the hollow shaft. The formation of the groove in the inner wall of the hollow shaft causes a large flow cross-section of the gas channel of the hollow shaft.

Particularly preferred is a guide geometry comprising at least one profiled sleeve. The sleeve bears against the inner wall of the hollow shaft. The use of a separate component in the form of a sleeve simplifies the manufacture of the conveyor. For mounting, the sleeve is inserted into the hollow shaft.

In this case, the guide geometry may comprise at least one helical groove in the sleeve. The liquid located on the inner wall of the hollow shaft is pressed by the gas flow into the groove and conveyed there in the longitudinal direction of the hollow shaft.

The groove may be formed on the outer circumference of the sleeve. Since the sleeve bears against the inner wall in the hollow shaft, a flow channel for the

Liquid bounded by the inner wall in the radial direction.

The groove may be formed on the inner circumference of the sleeve. To form a closed flow channel for the liquid, the groove can be closed in the radial direction, for example by a further component.

In a further preferred embodiment, a dip tube is arranged coaxially in the conveyor and relatively rotatable to the conveyor. Through the dip tube, the guided through the hollow shaft clean gas is discharged from the hollow shaft. The dip tube thus forms the gas outlet for the exit of the purified gas. This embodiment can be combined with both the inside and outside grooves in the sleeve.

Preferably, a liquid separator of the conveyor in

Preceded flow direction of the gas. By the liquid separator, the liquid contained in the gas is separated and passed by centrifugal forces in the direction of the inner wall of the hollow shaft.

When the liquid separator and the conveyor are arranged separately, i. If an axial distance is formed in the longitudinal direction of the hollow shaft between the liquid separator of the conveyor, the liquid is conveyed or entrained by the liquid from the liquid to the inner wall by the gas flow to the conveyor. The entering into the conveyor liquid is then forcibly guided by the rotational movement and the guide geometry in the longitudinal direction of the hollow shaft.

The liquid separator and the conveyor may also be integrated, i. be executed as a single component, so that the liquid separated in the liquid separator is transferred directly into the conveyor.

The liquid separator may comprise, for example, a baffle separator.

Preferably, the hollow shaft comprises a cam hollow shaft.

In the method according to the invention for separating a liquid from a gas stream, it is provided that the separated liquid flows along the inner wall of a hollow shaft. The liquid is forced through a helical conveyor in the hollow shaft in a combined movement in the circumferential and longitudinal direction of the hollow shaft. The positive guidance improves the drainage rate of the liquid from the hollow shaft.

The invention will be explained in more detail below with reference to embodiments with reference to the accompanying schematic drawings with further details. In this show

Fig. 1 is an exploded view of a hollow shaft after a

Embodiment according to the invention with on the outside sleeve arranged guide geometry;

Fig. 2 is a longitudinal section through the hollow shaft of Fig. 1 in mounted

State;

3 shows an exploded view of a hollow shaft according to a further embodiment of the invention with guide geometry arranged on the sleeve inside;

Fig. 4 is a longitudinal section through the hollow shaft of Fig. 3 in mounted

State;

Fig. 5 is an exploded view of a hollow shaft after a

Embodiment of the invention with integrated liquid separator and conveyor;

Fig. 6 is a longitudinal section through the hollow shaft of Fig. 5 in the mounted

State

Fig. 7 is a perspective view of the conveyor with integrated

Liquid separator according to Fig. 5 and

Fig. 8 is a longitudinal section through a hollow shaft after a

Embodiment of the invention with a coil spring as a conveyor.

The following are the same or similar components of the various

Embodiments provided with the same reference numerals. The basic structure of the hollow shaft, which is the same in the various embodiments, is explained in connection with Figures 1 and 2 and also applies to the other embodiments. Figures 1 and 2 show an embodiment of a hollow shaft 10 having a first and second axial end, which is used as a cam hollow shaft in a crankcase of an internal combustion engine. This is the preferred application of the hollow shaft 10. Other applications in which liquid is separated from a gas and passed through the hollow shaft are conceivable. In this example, it is the deposited and to be promoted

Liquid around oil.

The hollow shaft 10 has a Flüssigkeitsabscheidesystem 11, which in the

Figures 1 and 2 is not shown, and a conveyor 12 for the separated liquid. The Flüssigkeitsabscheidesystem 11 may include a liquid separator 24, which is formed as a separate component or integrated with the conveyor 12. The latter is shown in Fig. 5.

In the embodiment of FIG. 1, the Flüssigkeitsabscheidesystem 11 is formed separately from the conveyor 12 and may for example comprise a centrifugal separator, which is arranged at the first axial end of the hollow shaft 10 (not shown). The liquid separation system 11 is generally connected to the hollow shaft 10 such that the liquid deposited by the system 11 reaches the inner wall 13 of the hollow shaft 10 and is carried along by the gas guided through the hollow shaft 10. At the second, free axial end of the hollow shaft, an outlet 23 is formed for the conveyed through the hollow shaft 10 liquid. Through the outlet 23, the liquid passes out of the hollow shaft 10. In the example according to FIGS. 1, 2, the outlet 23 opens freely into the crankcase, generally into the space to be vented.

As a result, liquid is returned to the circulation.

The hollow shaft 10 forms a gas channel 15. In the example according to FIG. 1, the gas channel 15 is delimited by the inner wall 13 of the hollow shaft 10. The gas channel 15 has a gas inlet for the entry of raw gas that is loaded with the liquid, concretely with oil. The gas inlet is located at a first axial end of the hollow shaft 10 (not shown). The gas inlet may for example be integrated into the liquid separation system 11. The gas channel 15 has a gas outlet 17 for the outlet of the purified gas, which is arranged in the example of FIG. 1 at the second axial end of the hollow shaft 10. The outlet 17 may be connected to a conduit which supplies the cleaned gas to the exhaust tract of the internal combustion engine.

The conveyor 12 is rotatably connected to the inner wall 13 of the hollow shaft 10. This means that a torque of the hollow shaft 10 on the

Conveyor 12 is transmitted so that it rotates with the hollow shaft 10 with. The rotationally fixed connection can be made for example by a non-positive connection. Other connection options are conceivable. Under a rotationally fixed connection and the integration of the conveyor 12 is understood directly into the inner wall 13 of the hollow shaft 10. The connection is integral in this case. The conveyor 12 may in the case of one piece

Connection may be formed as a helical groove which is introduced into the inner wall 13.

The conveyor 12 has a helical guide geometry 14. The guide geometry 14 serves to convey the liquid located on the inner wall 13 in the longitudinal direction of the hollow shaft 10.

The above-described basic structure of the hollow shaft 10 is at all

Embodiments realized so. Deviations with a view to that

Liquid separation system (integrated or separate) are possible.

The conveyor 12 according to Figures 1, 2 has a profiled sleeve 20 which is arranged coaxially in the hollow shaft 10 in the mounted state (Fig. 2). The sleeve 20 rests against the inner wall 13 and is rotatably connected with this, for example, non-positively connected.

It is sufficient if the length of the sleeve 20 is dimensioned such that it is arranged in sections, for example only in the region of the rear, in the flow direction, free axial end of the hollow shaft 10. It is not necessary that the sleeve 20 is formed over the entire length of the hollow shaft 10, even if such a design is possible.

The sleeve 20 has a helical groove 21. The helical groove 21 is formed in the wall of the sleeve 20. The groove 21 runs on the in

Flow direction of the gas axial front end of the sleeve 20 flat. This ensures that the oil located on the inner wall 13 or

In general, the liquid can easily enter the conveyor 12. The groove

21 extends spirally or helically over the entire length of the sleeve 20. At the rear axial end 28 of the conveyor 12 in the flow direction, the groove opens into the outlet 23 for the liquid. There, the liquid is discharged from the hollow shaft 10. The outlet 23 forms an annular gap between the inner wall 13 of the hollow shaft 10 and the outer wall of a dip tube 22, which will be described in more detail below.

In the example according to FIGS. 1, 2, the groove 21 is formed on the outer circumference of the sleeve 20. The webs of the groove 21 are close to the inner wall 13 at. As a result, a sealed conveying channel for the liquid is formed, which extends helically along the inner wall 13 about the longitudinal axis of the hollow shaft 10.

In the embodiment of FIG. 2 are a plurality of threads

shown. The number of threads can vary. The depth and shape of the threads are exemplary and may vary as well. The thread cross section may vary along the axial length of the sleeve 20. Thus, a variation of the cross-sectional depth of the groove 21 over the length of the sleeve 20 is possible.

Between the sleeve 20 and the coaxially disposed in the sleeve 20 dip tube

22 is set a radial gap, so that the dip tube 22 and the sleeve 20 are rotatable relative to each other. The dip tube 22 is fixed to the housing during operation, i. stationary with respect to the hollow shaft 10, arranged.

As can be seen in FIGS. 1, 2, the conveying device 12 has a gas channel 27. The gas channel 27 of the conveyor 12 is limited by the inner circumference of the sleeve 20 and by the inner circumference of the dip tube 22, which is inserted into the sleeve 20. Through the gas channel 27 of the conveyor 12 flows from the gas channel 15 of the hollow shaft 10 coming purified gas and leaves the hollow shaft 10 through the gas outlet 17. The gas channel 15 of

Hollow shaft 10 and the gas channel 27 of the conveyor 12 are arranged coaxially. At the gas flow in the rear axial end 28 of the sleeve 20 and

Generally, the conveyor 12, the groove 21 passes into the outlet 23 for the liquid.

The dip tube 22 serves to remove the purified gases from the hollow shaft 10 controlled. The sleeve 20 is disposed between the dip tube 22 and the hollow shaft 10. In addition, the dip tube 22 together with the inner wall 13 of the hollow shaft 10 forms the outlet 23 for the liquid into which the groove

21 at the rear axial end 28 of the sleeve 20 opens. The front axial end (seen in the flow direction) of the dip tube 22 is arranged at approximately the same height as the front axial end of the sleeve 20.

In contrast to the groove 21 on the outside of the sleeve 20 according to FIG. 1, the embodiment according to FIGS. 3, 4 shows a sleeve 21 arranged internally on the groove 21 or generally internally arranged guide geometry 14. The groove 21 is formed on the inner circumference of the sleeve 20. The conveying channel for the liquid is through the groove 21 and the outer circumference of the dip tube

22 formed, against which the sleeve 20 and the webs of the groove 21 seal.

Otherwise, the exemplary embodiment according to FIGS. 3, 4 corresponds to FIG

Embodiment according to Figures 1, 2.

The exemplary embodiment according to FIGS. 5, 6 further forms the exemplary embodiment according to FIGS. 3, 4 in that the delivery device 12 has an integrated liquid separator 24. In other words, the Flüssigkeitsabscheidesystem 11 and the conveyor 12 is formed as a single component. The conveying direction 12 with the guide geometry 14 formed on the inner circumference of the sleeve 20 corresponds to the conveying device 12 according to FIGS. 3, 4.

Due to the integrated design of the liquid separator 24 with the

Conveyor 12, the separated liquid is discharged directly from the hollow shaft 10, without having to be moved on the inner wall 13 by the gas flow to the conveyor 12. For this purpose, the liquid separator 24 is formed as an impact separator 25. The impact separator 25 has in Flow direction in front of several passages 29, which are parallel to the

Longitudinal axis of the hollow shaft 10 extend.

In the example according to FIGS. 5 to 7, four passages 29 are provided. Another number is possible. In the flow direction behind the passages 29, a baffle plate 30 is arranged, which extends substantially perpendicular to the axis of the hollow shaft or to the longitudinal axis of the baffle separator 24. The baffle plate 30 overlaps the passages 29, so that the gas flow passing through the passages 29 strikes the baffle plate 30. Between the baffle plate 30 and the

Passages 29, a gap 32 is formed. At the passages 29

facing surface of the baffle plate 30 terminates the groove 21 of the sleeve 20, as shown in Fig. 6. Thus there is a fluid connection between the passages 29 and the groove 21 and between the gap 32 and the groove 21st

The opening on the surface of the baffle plate 30 in the gap 32 groove 21 is located radially further outward than the passages 29. This ensures that the deposited on the baffle plate 30 liquid, which flows radially outwardly by the centrifugal force, directly into the groove 21st and thus enters the conveyor 12.

The gas inlet 16 of the conveyor 12 is arranged coaxially with the longitudinal axis of the hollow shaft 10, so that the gas flowing through the passages 29 is discharged radially inwardly from the hollow shaft 10.

The combined with the liquid separator 24 conveyor 12 is non-positively connected by a connecting element 31, for example in the form of a fixing plate with the hollow shaft 10. The connecting element 31 in turn is positively connected to the one with the liquid separator 24

combined conveyor 12 connected. For this purpose, the

Liquid separator 24 on the outer circumference lugs 33, which extend radially outward and engage in the connecting element 31. This has the advantage that the conveyor 12 together with the

Liquid separator 24 may be made of a different material than the hollow shaft 10, without causing problems due to the different thermal expansion coefficients. Fig. 8 shows an embodiment in which the guide geometry 14 as

Coil spring 18 is formed. The helical spring 18 is cylindrical, so that the windings 19 of the helical spring 18 bear against the inner wall 13 of the hollow shaft 10. As a result, a delivery channel for the liquid 26 adhering to the inner wall 13 is formed.

The example according to FIG. 8 shows the variant in which the outlet 23 for the liquid is connected to a return chamber 34. The gas outlet 17 may for example be connected to the exhaust gas tract of the internal combustion engine.

Between the housing with the return chamber 24 and the hollow shaft 10, a dynamic radial seal in the form of a radial shaft seal is arranged. The Flüssigkeitsabscheidesystem 11 is the conveyor 12 in

Upstream flow direction. The hollow shaft 10 of FIG. 8 is an example of a system in which the Flüssigkeitsabscheidesystem 11 and the

Conveyor 12 separately, i. are formed as separate components.

All embodiments have in common that the shaft-mounted, helical guide geometry 14 is designed so that due to the rotation of the hollow shaft 10 of the inner wall 13 located liquid film or oil film is transported to the axial end of the hollow shaft 10. This principle is comparable to an Archimedean screw for pumping water. Due to the gravity of the liquid or the centrifugal force at high speeds at least the rotation of the hollow shaft 10 between the turns of the

helical Leitgeometrie 14 located liquid content of the

Shaft end promoted.

The forced delivery by the conveyor 12 provides the prerequisite that in the free outlet 23 (Figures 1 to 7), an additional seal is not required, so that blowby gases against the conveying direction of the liquid can flow into the hollow shaft 10, without the liquid removal significantly to hinder. It is therefore not necessary to seal the free shaft end consuming against the cam housing. It is even conceivable that the radial shaft seal of FIG. 8 is omitted. As a result, the number of components (radial shaft seal, clean gas duct, oil check valve, etc.) is reduced. The oil reservoir for the separated oil can be omitted. Compared to systems with radial shaft seal, the friction losses are reduced. Reference numeral list hollow shaft

Flüssigkeitsabscheidesystem

Conveyor

inner wall

Leitgeometrie

Gas channel of the hollow shaft

Gas inlet of the conveyor

Gas outlet of the hollow shaft

coil spring

turns

shell

groove

dip tube

outlet

liquid separator

impactor

liquid

Gas channel of the conveyor

Axial end of the conveyor

passage

flapper

connecting element

gap

nose

Return chamber

Claims

claims

1. hollow shaft (10) with

a liquid separation system (11),

a gas channel (15) having a gas inlet for the entry of raw gas and a gas outlet (17) for the discharge of purified gas, and

a conveying device (12) for conveying a gas separated from a gas,

wherein the conveyor (12) rotatably connected to an inner wall (13) of the hollow shaft (10) and a helical guide geometry (14) for conveying the liquid in the longitudinal direction of the hollow shaft (10).

2. Hollow shaft according to claim 1

dad u rch nets that net

the guide geometry (14) comprises at least one helical spring (18), the turns (19) of which bear against the inner wall (13).

3. Hollow shaft according to claim 1 or 2

dad u rch nets that net

the guide geometry (14) comprises at least one helical groove formed in the inner wall (13).

4. Hollow shaft according to one of the preceding claims

dad u rch nets that net

the guide geometry (14) comprises at least one profiled sleeve (20) which bears against the inner wall (13).

5. Hollow shaft according to claim 4

dad u rch nets that net

the guide geometry (14) comprises at least one helical groove (21) in the sleeve (20).

6. hollow shaft according to claim 5

dad u rch nets that net

the groove (21) is formed on the outer circumference of the sleeve (20).

7. hollow shaft according to claim 5

dad u rch nets that net

the groove (21) is formed on the inner circumference of the sleeve (20).

8. hollow shaft according to one of the preceding claims

dad u rch nets that net

a dip tube (22) is coaxially disposed in and relatively rotatable relative to the conveyor (12).

9. hollow shaft according to claim 8

dad u rch nets that net

an outlet (23) for the separated liquid between the

Conveying device (12) and the dip tube (22) is formed.

10. Hollow shaft according to one of the preceding claims

dad u rch nets that net

a liquid separator (24) of the conveyor (12) in

Direction of flow of the gas is upstream.

11. Hollow shaft according to claim 10

dad u rch nets that net

the liquid separator (24) and the conveyor (12) are integrated or arranged separately.

12. Hollow shaft according to claim 10 or 11

dad u rch nets that net

the liquid separator (24) comprises a baffle separator (25).

13. Hollow shaft according to one of the preceding claims

dad u rch nets that net

the hollow shaft comprises a cam hollow shaft.

14. A method for separating a liquid from a gas stream, in which the separated liquid flows along the inner wall (13) of a hollow shaft (10), wherein the liquid by a helical conveyor (12) in the hollow shaft (10) in a combined Movement in the circumferential and longitudinal direction of the hollow shaft (10) is positively guided.