Oil separator having first and second gas inlets and gas outlets

Abstract

An oil separator for separating oil droplets and/or oil mist from gases, in particular from blow-by gases of an internal combustion engine is described.

Claims

1. An oil separator for separating oil droplets and/or oil mist from gases to be cleaned, comprising: a housing, a rotor, which has an oil separating element, arranged in the housing and spaced from the housing, and a shaft for rotatably mounting the oil separating element, a first gas inlet for supplying gases to be cleaned to the oil separating element along the shaft and a first gas outlet in the wall of the housing which surrounds the rotor, a second gas inlet for supplying gases to be cleaned is arranged in the wall of the housing which surrounds the rotor, and a second gas outlet in the wall of the housing which surrounds the rotor.

2. The oil separator according to claim 1, wherein the first gas inlet and the second gas inlet are connected to a common gas supply line outside or inside the housing.

3. The oil separator according to claim 1, wherein the second gas inlet is configured in such a way that through-flowing gas flows into the housing substantially tangentially along the wall of the housing.

4. The oil separator according to claim 1, wherein the second gas outlet is closed by a second valve, which is pre-loaded for a specified opening characteristic or is actively controllable, via a motor control or an actuator, selected from the group of a servomotor, an actuating element or a pressure sensor.

5. The oil separator according to claim 1, wherein the second inlet and the second outlet are arranged at opposite sides of the oil separating element.

6. The oil separator according to claim 1, wherein the second inlet and the second outlet are arranged adjacent or immediately adjacent to one another in the direction of rotation of the rotor, and/or the second inlet and the second outlet are arranged adjacent or immediately adjacent to one another perpendicularly to the direction of rotation of the rotor.

7. The oil separator according to claim 1, wherein the second inlet and the second outlet are arranged at the same height or offset from one another as viewed parallel to the axis of the shaft.

8. The oil separator according to claim 1, further comprising a drive element for driving the oil separating element of the rotor via the shaft.

9. The oil separator according to claim 8, wherein the drive element is a hydraulically driven drive element, selected from the group of a Heron turbine or a Pelton turbine.

10. The oil separator according to claim 8, wherein the drive element is an electrically driven drive element.

11. An oil separator for separating oil droplets and/or oil mist from gases to be cleaned, comprising: a housing, a rotor, which has an oil separating element, arranged in the housing and spaced from the housing, and a shaft for rotatably mounting the oil separating element, a first gas inlet for supplying gases to be cleaned to the oil separating element along the shaft and a first gas outlet in the wall of the housing which surrounds the rotor, and a second gas inlet for supplying gases to be cleaned is arranged in the wall of the housing which surrounds the rotor, wherein the second gas inlet is closed by a first valve which is pre-loaded for a specified opening characteristic or is actively controllable, via a motor control or an actuator, selected from the group of a servomotor, an actuating element or a pressure sensor.

12. The oil separator according to claim 11, wherein the first valve opens the second gas inlet when a specified volume flow through the first gas inlet is exceeded and/or when a specified pressure difference between the gas on the pressure side of the first valve and the suction side of the first valve in the interior of the housing is exceeded.

13. An oil separator for separating oil droplets and/or oil mist from gases to be cleaned, comprising: a housing, a rotor, which has an oil separating element, arranged in the housing and spaced from the housing, and a shaft for rotatably mounting the oil separating element, a first gas inlet for supplying gases to be cleaned to the oil separating element along the shaft and a first gas outlet in the wall of the housing which surrounds the rotor, and a second gas inlet for supplying gases to be cleaned is arranged in the wall of the housing which surrounds the rotor, wherein a first valve and/or a second valve each have a valve opening, a valve seat and a valve closure, wherein either the valve closure is formed as a movable spring tongue which covers the valve opening and, on the side facing the valve opening, is coated with an elastomer, with a closed-cell elastomer, at least in sections, or the valve is formed as a mushroom valve having a valve screen made of an elastomer material as said a valve closure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The drawings show:

(2) FIG. 1 an oil separator according to the prior art; and

(3) FIGS. 2-6 oil separators according to the present invention;

(4) FIG. 7 the pressure loss across the blow-by channels of an internal combustion engine depending on the volume flow in a comparison between a conventional oil separator and an oil separator according to the present invention.

DETAILED DESCRIPTION

(5) FIG. 1 shows an oil separator 1 according to the prior art. This oil separator 1 has a housing 2 which encloses an oil separating chamber 7. A rotor 3, which has a stack of plates arranged on top of one another, is arranged in the oil separating chamber 7. Clearances are located between the individual plates. The plate stack 3 is mounted on a shaft 4 and can be set in rotation by this shaft 4.

(6) The housing 2 is surrounded by a further outer housing/wall 8, wherein both the gas supply and the transfer of the gleaned gas are arranged between the housing 2 and the outer housing 8.

(7) Via a supply line 5, as a gas inlet, which is guided between the housing 2 and an outer wall 8, the gas, which is to be cleaned of oil mist and/or oil droplets, is supplied substantially centrally to the plate stack along the shaft 4. The gas then flows through between the individual plates of the plate stack 3 and exits these along their circumferential edge into the outer region of the oil separating chamber 7 in the region between the plate stack 3 and the wall of the housing 2. Owing to the rotation of the plate stack 3, the gas flowing through the plate stack 3 is set in rotation and accelerated so that oil mist and oil droplets are separated both on the surfaces of the plates and on the wall of the housing 2. They are subsequently collected in the lower region of the oil separating chamber 7 and discharged from the oil separating chamber 7 in a manner which is not illustrated. The cleaned gas then exits the oil separating chamber 7 via the gas outlet 6.

(8) In the case of internal combustion engines, by means of an oil separator 1 of this type, blow-by gas, in particular, is introduced into the oil separator 1 from the crankcase via the gas inlet 5 and then supplied as cleaned blow-by gas to the intake tract of the internal combustion engine via the gas outlet 6.

(9) In the case of very high blow-by gas volume flows, due transfer of the blow-by gas through the oil separator 1 cannot take place since the capacity thereof is limited by the cross-sections of the inlet 5, the clearances between the plates of the plate stack 3, the geometry of the housing 2 and the cross-section and the geometry of the outlet 6 with a given available pressure difference across the oil separator. The pressure difference across the oil separator is consequently inadmissibly high.

(10) Conventionally, additional bypass lines are therefore provided around the oil separator 1, wherein oil separation and cleaning of the blow-by gas before it enters into the intake tract of the internal combustion engine do not take place, or only take place to a negligible extent.

(11) According to the invention, in the oil separator according to FIG. 2, a second gas inlet 10 into the oil separating chamber 7 is now arranged in the housing 2. This second gas inlet 10 has a mushroom valve 11 having a valve seat 12, a valve opening 13 and a valve disc 14 formed in the shape of a mushroom. In this case, FIG. 2A shows the valve in a sectional illustration.

(12) When a specified volume flow or a specified pressure difference between the pressure side and the suction side (oil separating chamber 7) of the valve 11 is exceeded, the valve disc of the mushroom valve lifts away from the valve seat 12 and frees a passage between the supply line and the oil separating chamber 7. As a result, further gas can now flow into the oil separating chamber 7. This gas no longer flows through the clearances between the plates of the plate stack 3 but, owing to the rotation of the plate stack and the gas surrounding it, is carried along in a rotational motion along the inside of the wall 2 and thus likewise cleaned of oil droplets and oil mist. The mushroom valve at the same time serves as a non-return valve in order to prevent gas from flowing out of the oil separating chamber 7 via the second gas inlet 10.

(13) In the oil separating chamber 7 between the rotor 3 and the wall of the housing 2, the gas flows, namely the gas flow which has flowed through the plate stack 3 and the gas flow which has entered the oil separating chamber 7 via the mushroom valve 11, consequently mix together and subsequently exit the oil separating chamber 7 via a gas outlet 6 of sufficiently large dimensions.

(14) FIG. 2A shows an oil separator 1 with only a small volume flow of the gas to be cleaned, i.e. with a closed mushroom valve 11.

(15) FIG. 2B shows a section through the oil separator 1 in the same state, wherein the mushroom valve 14 is now also shown in a sectional illustration here. In this case, as in the following FIGS. 2C to 5B, the plate stack 3 is only indicated schematically as a block.

(16) FIG. 2C shows the oil separator 1 with an open valve 11 in the case of a high volume flow of the gas to be cleaned.

(17) FIG. 3 shows a further oil separator 1, which is formed in the same manner as that illustrated in FIG. 2.

(18) However, the housing 2 additionally has a second gas outlet 20, which is configured as a mushroom valve 21. The mushroom valve 21 has a valve seat 22, a valve opening 23 and a valve disc 24 of an elastomer material.

(19) The passage direction of the valve 11 leads from the inlet 5 into the oil separating chamber 7, whilst the opening direction of the valve 21 is directed from the oil separating chamber 7 into the gas line following the gas outlet 6. In this case, both mushroom valves are, at the same time, also non-return valves so that the valve 11 in any case prevents the flow of gas from the oil separating chamber 7 in the direction of the gas inlet and the mushroom valve 21 prevents the flow of cleaned gas into the oil separating chamber 7.

(20) In FIG. 3A, both valves are closed with a low volume flow.

(21) In FIG. 3B, both valves are open, i.e. in an operating point in which the volume flow of the gases to be cleaned is very high. In this case, the opening characteristic of the valves 11 and 12 can be similarly configured so that both valves open and close at the same time. Depending on requirements, however, it is also possible to provide both valves 11 and 12 with different opening characteristics. The same applies to the closing characteristics of the valves 11 and 21.

(22) Therefore, in FIG. 3C for example, a state is illustrated in which the second outlet valve 21 is closed whilst the second inlet valve 11 is opened via the valve opening.

(23) In FIG. 3D, a state is illustrated in which the second outlet valve 21 is open whilst the second inlet valve 11 is now closed. Such different opening and closing characteristics of the valves 11 and 21 can be set via a suitable material choice and configuration of the valves.

(24) The states illustrated in FIGS. 3C and 3D can be realised for example when the inflow into the first gas inlet via the supply line 5 is limited or blocked (FIG. 3C) or when the discharge flow through the first gas outlet is limited or blocked (FIG. 3D), for example if local freezing occurs.

(25) In contrast to the embodiments shown in FIGS. 3A to 3C, a further two collars 25, 26 extending circumferentially around the second gas outlet 20 on the inside of the housing 2 have been added in FIG. 3D, which collars, as a type of labyrinth seal, help to prevent the entrainment of oil as gas passes through the gas outlet 20 and out of the area surrounding the gas outlet 20. Comparable collars can also be attached around the second gas inlet opening 10 on the outside of the housing 2 in order to prevent the entrainment of oil which is separated when it impacts against the housing 2. However, a separate illustration has been omitted here.

(26) In two partial FIGS. 4A and 4B, FIG. 4 shows a further oil separator according to the invention, which is configured in the manner of the oil separator in FIG. 2. In contrast to FIG. 2, however, the second gas inlet 10 is now provided with another valve construction 11. As the valve 11, a valve opening 13 is provided within a valve seat 12 here, which valve opening can be closed and opened via a flexible spring tongue 14. The spring tongue is secured, for example screwed or riveted, to a support 15 as a securing point on the valve seat 12. In this case, the opening characteristic of the spring tongue 14 can be set via the choice of material thickness, material, geometric form of the transition between the securing point 15 and the free end of the spring tongue 14 and further parameters. It can be advantageous if the side of the spring tongue 14 which faces the valve opening 13 is coated with a closed-cell elastomer material 16, as illustrated in FIG. 4B. In this case, a particularly high oil separating capacity is realised on this spring tongue 14 when gas flows through the opening gap between the valve seat 12 and the spring tongue 14. Instead of the partial coating illustrated, a full surface coating is also possible, or the spring tongue 14 can be produced from spring hard sheet metal with a full surface elastomer coating, at least on the side facing the valve seat 12.

(27) In two partial FIGS. 5A and 5B, FIG. 5 shows a further example of an oil separator 1 according to the invention, which is configured in the manner of the oil separator in FIG. 4. However, corresponding to FIG. 3, the housing 2 has a second outlet 20 in its wall, which is configured similarly as a valve in the same manner as the gas inlet 10. Only the opening direction is formed as in FIG. 3, i.e. the first valve 11 opens in the direction of the oil separating chamber 7 whilst the second valve 21 opens in the direction of the gas outlet 6 or the gas line mounted downstream of the gas outlet 6.

(28) In FIG. 5B, the oil separator 1 is illustrated in the case of a high volume flow of the gas to be cleaned. Both valves 11 and 21 are open and enable a flow through the oil separating chamber without the corresponding volume flow being guided completely through the plate stack 3.

(29) Instead of the spring tongues 14 which are used in FIGS. 4 and 5 and secured via a single holding arm, it is also possible to use a spring shim which is secured via two holding arms, as is disclosed for instance in DE 20 2014 006 149 U1, for example in FIGS. 1 and 2 It is likewise possible to use a valve shim which lifts away centrally, as is disclosed for instance in EP 1 743 110 A1 in FIG. 1. Further geometric configurations for this are revealed for instance in the figure group 15 of DE 20 2015 103 420.

(30) In FIG. 3 and FIG. 5, the first valve 11 and the second valve 21 are each arranged opposite one another in the wall of the housing 2. In this case, the valves are slightly offset from one another in the axial direction of the shaft 4. However, an arrangement which is not offset or a non-opposite arrangement is also possible.

(31) FIG. 6 shows a further oil separator 1 corresponding to that in FIG. 2. It is clear from this illustration that gas flowing through the second gas inlet flows substantially tangentially along the wall of the housing 2 into the oil separating chamber 7 and is therefore carried along immediately by the plate stack 3 or its surrounding gas flow. As a result of the tangential inflow, the rotational motion of the gas flowing in via the second gas inlet 10 is reinforced so that a further improved oil separation from this part of the gas flow is also realised. In the previous embodiments, the gas inlets of the oil separators likewise have at least one tangential inlet part relative to the turn of the housing 2.

(32) FIG. 7 now shows a comparison of the pressure loss depending on the volume flow between the gas inlet and the gas outlet. The line provided with black dots in this case shows the pressure loss in a conventional oil separator. The pressure loss continues to rise as the volume flow increases; in other words, this means that, with a given available pressure difference between the outlet and inlet side of the oil separator, the gas flow flowing through the oil separator is limited.

(33) The curve illustrated without solid dots shows the pressure loss depending on the volume flow for an inventive oil separator according to FIG. 2. Owing to the arrangement of the additional second gas inlet, which is revealed as a bypass around the oil separating element, it is brought about that the pressure loss remains limited even as the volume flow of the gas to be cleaned continues to rise. In other words, with an available pressure difference between the outlet and inlet of the oil separator 1, it is also possible for a high volume flow to be conducted through the oil separator and at least fundamentally cleaned. In the case of the present oil separator according to the present invention, some of the gas to be cleaned is always conducted through the oil separating element 3 in this case and thereby cleaned substantially completely of oil mist and oil droplets. However, the gas to be cleaned which is not conducted through the oil separating element 3 is also accelerated in the oil separating chamber 7 and therefore substantially cleaned of oil mist and oil droplets, so that the gas flowing out of the oil separator 1 is, on the whole, also substantially cleaned in the case of high volume flows and/or a limited available pressure difference across the oil separator.