DE102019008157A1 - Electrostatic precipitator - Google Patents

Abstract

The present invention relates to an electrical separator for separating liquid and / or solid particles from a gas flow, in particular from a blow-by gas of a crankcase ventilation, of an internal combustion engine, comprising an emission electrode and a counter electrode, to which a high electrical voltage can be applied so that between an electrical high-voltage field can be generated between the emission electrode and the counterelectrode, wherein a receiver surface of the counterelectrode facing the emission electrode is at least partially provided with an anti-adhesive layer and the anti-adhesive layer is at least partially offset with electrically conductive particles.

Description

The present invention relates to an electrical separator for separating liquid and / or solid particles from a gas flow, preferably from a blow-by gas from a crankcase ventilation, in an internal combustion engine.

Separators, in particular oil separators, are known in the prior art. There are generally two types of separators, namely passive separators and active separators. With passive separators, no additional energy is introduced into the system in order to remove the particles from the gas flow. Active separators are characterized by the fact that additional energy is used to separate the particles from the gas flow. For example, an electrodeposition system is known in which particles located in the gas flow are electrically charged so that they can be attracted to a surface of opposite polarity and then deposited. In the case of oil separators in particular, the oil particles are returned to the oil circuit and the cleaned gas flow is returned to the intake air of the internal combustion engine.

Such an electrostatic precipitator is off, for example WO 2016/147 127 A1 known. The electrostatic precipitator comprises a multiplicity of emission electrodes, by means of which a direct voltage which exceeds the breakdown voltage can be generated for the formation of a stable low-energy plasma, and a multiplicity of counter electrodes which are assigned to the emission electrodes. The needle-shaped emission electrodes are each assigned to a counter electrode in such a way that the emission electrodes are positioned essentially vertically above the counter electrodes. The counter-electrodes have a curved plateau area that merges into a flat web section, which in turn is connected to a frame structure that connects a number of counter-electrodes and on which the counter-electrodes are arranged at a distance from one another, distributed along the direction of flow of the gas flow.

However, disadvantages have arisen in this tried and tested electrodeposition technique. On the one hand, the efficiency of the electrostatic precipitator is adversely affected by the fact that there is always a counter-electrode-free area at a distance from two counter-electrode plateaus, which cannot contribute to the separation. Furthermore, it was found that deposited particles tend to accumulate on the counter electrode plateaus. The accumulation of particles on the counter-electrodes has a disadvantageous effect on the longevity of the electrostatic precipitator, since the counter-electrodes become increasingly contaminated and have to be replaced. On the other hand, undesired plasma ignitions on the counter electrode can occur.

DE 29809320 U1 discloses an electrostatic precipitator for removing emissions from an air stream. The electrostatic precipitator comprises a receiving plate for attracting and storing the emission particles located in the air flow and to be separated therefrom. In order to facilitate cleaning of the receiving plates, the receiving plates have a non-stick coating, for example made of PTFE, in order to reduce the adhesive force between the receiving plate surface and the separated particles. With the electrostatic precipitator according to DE 29809320 U1 However, it has been shown that the electric field is not generated reliably enough or it can happen that the electric field is not strong enough to electrically charge the emission particles in the air flow. Accordingly, the PTFE non-stick coating leads to a reduction in the separation rate of the electrostatic precipitator.

One object of the present invention is to improve the disadvantages of the prior art, in particular to provide an electrostatic precipitator in which the deposition of deposited particles on the counter electrode is reduced, in particular avoided, preferably without reducing the separation efficiency of the electrostatic precipitator.

The object is achieved by the subject matter of claims 1 and 6, respectively.

According to one aspect of the present invention, an electrostatic precipitator is provided for separating liquid and / or solid particles, such as oil particles, from a gas flow, in particular from a blow-by gas of a crankcase ventilation, of an internal combustion engine. In an exemplary application of an electric separator according to the invention in a motor vehicle with an internal combustion engine, blow-by gases arise between a working piston and a cylinder in which the working piston is accommodated in a crankcase interior of the internal combustion engine. Alternatively, so-called blow-by gases also occur between the cylinder and the cylinder head and / or between the cylinder head and the cylinder head cover of an internal combustion engine, such as a reciprocating piston engine. In addition to air and oil, blow-by gases usually also contain combustion gases and unburned fuel components, which can have negative effects on the function of the internal combustion engine. For example, the pressure increase caused by the blow-by gas flow in the crankcase is reduced, preferably avoided, by means of a crankcase ventilation which is coupled to the fresh air supply of the internal combustion engine by means of a line system. in the The course of the flow direction within the crankcase ventilation can be arranged, for example, an electrical separator according to the invention, in particular such that the blow-by gas flow comprising combustion gases and / or unburned fuel components is fed to the electrical separator, in which a separation, in particular oil separation, of liquid and / or solid particles such as oil particles, so that the separated particles can be removed from the gas flow and the preferably cleaned gas flow can be fed to the fresh air supply without damaging the internal combustion engine. The electrostatic precipitator according to the invention is preferably an active separation device in which, as already stated above, additional energy is introduced into the separation system.

The electrostatic precipitator works essentially according to the following principle: release of electrical charges, especially electrons; Charging the particles in an electric field; Transport of the electrically charged particles to an opposite pole; Discharging the charged particles at the opposite pole; and removing the particles from the opposite pole.

The electrostatic precipitator according to the invention comprises an emission electrode and a counter electrode. The counter electrode and the emission electrode can be insulated from one another and / or each can be made from one piece. The emission electrode, also called a spray electrode, essentially serves to emit, preferably negatively charged, particles. The counter electrode, also called the collecting electrode, forms the opposite pole. An electrical high voltage can be applied to the emission electrode and the counter electrode, so that an electrical high voltage field can be generated between the emission electrode and the counter electrode. For example, the high voltage is in the range of 8-20 kV, preferably in the range of 10-16 kV or in the range of 11-14 kV. For example, the space formed between the emission electrode and the counter electrode can be referred to as a separation space. During the operation of the electrostatic precipitator, an electrical high voltage is applied between the emission electrode and the counter electrode, so that a high voltage field is generated between the emission electrode and the counter electrode. The electrostatic precipitator is preferably operated below the breakdown or flashover voltage. The breakdown voltage, also called flashover voltage, is the voltage that must be exceeded in order for a voltage breakdown through a material or substance, e.g. B. an insulator, or gas. For example, the principle of charge generation on which the electrostatic precipitator is based can be impact ionization. When a so-called corona field strength is exceeded, electrons emerge from the emission electrode and interact with the surrounding gas molecules, whereby a so-called negative corona is formed. Free electrons present in the gas are strongly accelerated in the electrostatic field of the corona, so that a gas discharge can occur. When they hit gas molecules, further electrons can be split off or attach to the gas molecules. The negative charges then move in the direction of the oppositely charged counter electrode. When a particle-charged gas flow enters, the negatively charged charges attach to the particles. As a result of the electrical force of the applied direct voltage field transversely to the direction of flow of the gas flow, the negatively charged particles migrate in the direction of the counter electrode, where they can release their charge again. Liquid particles, such as oil particles, can then flow off or drip off the counter electrode and thereby be separated from the gas flow, while a preferably cleaned gas flow, such as a clean air gas flow, can leave the electrostatic precipitator again. It is clear that the present invention also covers embodiments in which a positive electroemission electrode / a positive corona / positively charged charges are used instead of the negative emission electrode / the negative corona / the negatively charged charges. To avoid repetition, the description of the invention is limited to the design of the negative emission electrode.

The counter electrode has a receiver surface facing the emission electrode for receiving electrically charged particles. According to one aspect of the present invention, the receiver surface is at least partially provided with a non-stick layer. The non-stick layer can be designed, for example, to reduce frictional resistance between the particles hitting the receiver surface and the receiver surface. For example, the non-stick layer reduces the adhesive force between the receiver surface and the electrically charged particles, which can also be referred to as filter residues. Furthermore, the non-stick layer is offset with electrically conductive particles at least in some areas and / or at certain points. As a result, a certain minimum electrical conductivity is applied to the non-stick layer in order to ensure the intended operation of the electrostatic precipitator and to implement a reliable formation of the high-voltage electrical field. Finally, the measure according to the invention brings about an increase in the deposition rate. The inventors of the present invention have found that in this way the partially contradicting requirements Non-stick layers can be taken into account in the field of application of electrostatic precipitators, namely to provide a minimum electrical conductivity, the highest possible anti-stick effect and high stability against the charge carrier bombardment caused by the electrostatic field, whereby the generation of the high-voltage electrical field must not be negatively influenced. For example, the electrically conductive particles can be embedded in the non-stick layer. For example, it is possible to apply the non-stick layer to the counter electrode by spraying, printing or by a rolling process. In addition, it is possible to manufacture the counter-electrode in such a way that the separation surface is made from the material of the anti-adhesive layer during manufacture.

According to an exemplary embodiment of the present invention, the receiver surface merges into a deposition surface facing away from the emission electrode. For example, the receiver surface and / or the transition between receiver surface and separation surface are / is formed in such a way that flow obstacles such as edges, a collection point such as tubs are avoided. For example, only the receiver surface faces the emission electrode, while the deposition surface only faces away from the emission electrode. For example, the counter electrode can have a rotationally symmetrical shape, preferably an ellipsoidal shape, in particular a spherical shape. The receiver surface and the deposition surface can together form a complete outer side or outer surface of the counter electrode, with an area of the outer side or outer surface facing the emission electrode defining the receiving surface and an area of the outer side or outer surface facing away from the emission electrode defining the deposition surface. According to an exemplary development of the electrical separator according to the invention, several emission electrodes, preferably in the range from 10 to 200 emission electrodes, in particular in the range from 20 to 150 emission electrodes, and several counter electrodes are provided, with one emission electrode each facing and assigned to a counter electrode so that between each Emission electrode counter-electrode pair, the high-voltage electrical field can be generated. According to an exemplary development, the receiver surface merges into the separation surface without any edges, protrusions and / or steps. This prevents flow obstacles from occurring in the area of the transition between the receiver surface and the separation surface and / or along the flow path of the particles away from the receiver surface, which could cause the particles to collect and / or deposit on the counter electrode. For example, the separation surface has a lower non-stick effect than the recipient surface. Furthermore, it can be provided that the separation surface is essentially free of an anti-adhesive layer. For example, the counter electrode can be made from one piece and / or the receiver surface and the separation surface can be made from the same material. The non-stick layer can be applied to the receiver surface in a subsequent manufacturing step and / or coating step.

According to a further exemplary embodiment of the electrical separator according to the invention, the non-stick layer comprises plastic, preferably fluorine-based plastic, in particular PTFE, FEP and / or PFA and / or a thermoplastic plastic, preferably PEEK. The specified materials are suitable, on the one hand, to prevent the deposition of particles on the receiver surface and, on the other hand, the materials mentioned do not lead to the deposition rate being reduced, for example because the electrical high-voltage field is not generated reliably and / or strongly enough .

According to an exemplary development, the non-stick layer has a layer thickness in the range from 1 μm to 100 μm. It has been found that even very small layer thicknesses are sufficient to achieve a significant improvement with regard to the avoidance of deposits. It was also found that the non-stick effect of the non-stick layer depends largely on the surface properties of the non-stick layer and / or the receiver surface, not necessarily or negligibly on its layer thickness. In this respect, a sufficiently strong anti-stick effect to avoid deposits can be achieved even with low layer thicknesses in the range of 1 μm to 100 μm mentioned.

In a further exemplary embodiment of the electrostatic precipitator according to the invention, the electrically conductive particles comprise metal or graphite, in particular preferably consist exclusively of metal or graphite. The cited materials for the electrically conductive particles have proven to be particularly efficient with regard to ensuring that the high-voltage electrical field is maintained, in particular in combination with a non-stick layer made of the cited plastic materials.

According to a further aspect of the present invention, which can be combined with the preceding aspects and exemplary embodiments, is an electrostatic precipitator for separating liquid and / or solid particles, such as oil particles, from a gas flow, in particular from a blow-by gas of a crankcase ventilation, an internal combustion engine provided. At a In an exemplary application of an electric separator according to the invention in a motor vehicle in an internal combustion engine, blow-by gases arise between a working piston and a cylinder in which the working piston is accommodated in a crankcase interior of the internal combustion engine. Alternatively, so-called blow-by gases also occur between the cylinder and the cylinder head and / or between the cylinder head and the cylinder head cover of an internal combustion engine, such as a reciprocating piston engine. In addition to air and oil, blow-by gases usually also contain combustion gases and unburned fuel components, which can have negative effects on the function of the internal combustion engine. For example, the pressure increase caused by the blow-by gas flow in the crankcase is reduced, preferably avoided, by means of a crankcase ventilation which is coupled to the fresh air supply of the internal combustion engine by means of a line system. In the course of the direction of flow within the crankcase ventilation, for example, an electrical separator according to the invention can be arranged, in particular such that the blow-by gas flow comprising combustion gases and / or unburned fuel components is fed to the electrical separator, in which a separation, in particular oil, of liquid and / or solid particles, such as oil particles, so that the separated particles can be removed from the gas flow and the preferably cleaned gas flow can be fed to the fresh air supply without damaging the internal combustion engine. The electrostatic precipitator according to the invention is preferably an active separation device in which, as already stated above, additional energy is introduced into the separation system.

The electrostatic precipitator works essentially according to the following principle: release of electrical charges, especially electrons; Charging the particles in an electric field; Transport of the electrically charged particles to an opposite pole; Discharging the charged particles at the opposite pole; and removing the particles from the opposite pole.

The electrostatic precipitator according to the invention comprises an emission electrode and a counter electrode. The counter electrode and the emission electrode can each be made from one piece. The emission electrode, also called a spray electrode, essentially serves to emit, preferably negatively charged, particles. The counter electrode, also called the collecting electrode, forms the opposite pole. An electrical high voltage can be applied to the emission electrode and the counter electrode, so that an electrical high voltage field can be generated between the emission electrode and the counter electrode. For example, the high voltage is in the range of 8-20 kV, preferably in the range of 10-16 kV or in the range of 11-14 kV. For example, the space formed between the emission electrode and the counter electrode can be referred to as a separation space. During the operation of the electrostatic precipitator, an electrical high voltage is applied between the emission electrode and the counter electrode, so that a high voltage field is generated between the emission electrode and the counter electrode. The electrostatic precipitator is preferably operated below the breakdown or flashover voltage. The breakdown voltage, also called flashover voltage, is the voltage that must be exceeded in order for a voltage breakdown through a material or substance, e.g. B. an insulator, or gas. For example, the principle of charge generation on which the electrostatic precipitator is based can be impact ionization. When a so-called corona field strength is exceeded, electrons emerge from the emission electrode and interact with the surrounding gas molecules, whereby a so-called negative corona is formed. Free electrons present in the gas are strongly accelerated in the electrostatic field of the corona, so that a gas discharge can occur. When they hit gas molecules, further electrons can be split off or attach to the gas molecules. The negative charges then move in the direction of the oppositely charged counter electrode. When a particle-charged gas flow enters, the negatively charged charges attach to the particles. As a result of the electrical force of the applied direct voltage field transversely to the direction of flow of the gas flow, the negatively charged particles migrate in the direction of the counter electrode, where they can release their charge again. Liquid particles, such as oil particles, can then flow off or drip off the counter electrode and thereby be separated from the gas flow, while a preferably cleaned gas flow, such as a clean air gas flow, can leave the electrostatic precipitator again.

The counter electrode has a receiver surface facing the emission electrode for receiving electrically charged particles. The receiver surface is at least partially provided with a non-stick layer. The non-stick layer can be designed, for example, to reduce frictional resistance between the particles hitting the receiver surface and the receiver surface. For example, the non-stick layer reduces the adhesive force between the receiver surface and the electrically charged particles, which can also be referred to as filter residues. According to a further aspect of the present invention, the anti-stick layer has a Layer thickness of less than 200 nm. Contrary to the general prejudice that such a small layer thickness of the anti-stick layer only has a very short service life, the inventors of the present invention have found that the service life is significantly extended by providing an oil protective coating on the anti-stick layer. The electrically insulating effect of the oil protection layer ensures that the counter electrode and the non-stick layer are protected from the impacting electrically charged particles. Furthermore, the inventors of the present invention have found that, especially when using the electrostatic precipitator to separate oil particles, in particular from a blow-by gas of a crankcase ventilation, the separated oil particles form the advantageous oil protection coating, so that no additional oil protection coating is necessary. Alternatively, the oil protection coating can also be applied separately from the outside.

According to an exemplary development of the present invention, the non-stick layer is implemented as an electrical insulator with an electrical conductivity of less than 10 ^-8 S * cm ^-1 and / or a specific resistance of at least 107 Ω * cm. The inventors of the present invention have also found that the non-stick effect of the non-stick layer depends largely on its surface properties, so that even a very thin layer thickness of less than 200 nm is sufficient. According to the invention, the layer thickness of the anti-stick layer is selected to be so small that the anti-stick layer does not actually represent an insulator and thus a sufficiently strong and / or reliable electrical high-voltage field is formed between the counter electrode and the emission electrode.

In a further exemplary embodiment of the present invention, the non-stick layer, in particular the electrical insulator, comprises a substance with a silicon-based chemical compound, in particular silicon dioxide or fluorosilane.

In a further exemplary development of the present invention, the anti-stick layer is applied to the counter-electrode by spraying or spraying the counter-electrode or by immersing the counter-electrode in an anti-stick layer bath. Furthermore, the non-stick layer can also be applied by a rolling process.

For example, the so-called contact angle, also known as the edge or wetting angle, between liquid particles, in particular liquid droplets, and the receiver surface can be used to determine the non-stick effect. In an analogous manner, reference can be made to the determination of the surface free energy and / or the contact angle based on the DIN 5660-2 “Coating materials wettability part 2: Determination of the surface free energy of fixed surface diameter of the contact angle”, which is fully integrated with reference become. In summary, the following relationship can generally be established: A contact angle of less than 90 ° indicates a weak non-stick effect; a contact angle of about 90 ° indicates an indifferent and / or neutral and / or moderately strong to moderately weak non-stick effect; a contact angle of over 90 ° means, according to the present invention, a strong non-stick effect. To determine the contact angle, for example, the Owens-Wendt-Rabel-Kaelble (OWRK) method known in the literature can be used.

According to a further aspect of the present invention, which can be combined with the preceding aspects and exemplary embodiments, is an electrostatic precipitator for separating liquid and / or solid particles, such as oil particles, from a gas flow, in particular from a blow-by gas of a crankcase ventilation, an internal combustion engine provided. The electrostatic precipitator works essentially according to the following principle: release of electrical charges, especially electrons; Charging the particles in an electric field; Transport of the electrically charged particles to an opposite pole; Discharging the charged particles at the opposite pole; and removing the particles from the opposite pole.

The electrostatic precipitator comprises an emission electrode and a counter electrode. The counter electrode and the emission electrode can be insulated from one another and / or each can be made from one piece. The emission electrode, also called a spray electrode, essentially serves to emit, preferably negatively charged, particles. The counter electrode, also called the collecting electrode, forms the opposite pole. An electrical high voltage can be applied to the emission electrode and the counter electrode, so that an electrical high voltage field can be generated between the emission electrode and the counter electrode. For example, the high voltage is in the range of 8-20 kV, preferably in the range of 10-16 kV or in the range of 11-14 kV.

The counter electrode has a receiver surface facing the emission electrode for receiving electrically charged particles. The receiver surface is curved in the direction of the emission electrode and goes all the way round continuously into a separation surface of the counter-electrode facing away from the emission electrode. For example, is / is the receiver surface and / or the transition between the receiver surface and separation surface formed in such a way that flow obstacles, such as edges, a collection point, such as tubs, are avoided. As an alternative or in addition, the counter electrode can extend along the row of emission electrodes, preferably in a straight line. Furthermore, the counter electrode can have a cross section with a receiver surface facing the emission electrodes for receiving electrically charged particles, which is curved in the direction of the emission electrode row. Furthermore, the cross section of the counter electrode is constant along its longitudinal extent, at least in the region of the receiver surface. Alternatively or additionally, the counter electrode can be offset with respect to the emission electrode, preferably in or against the flow direction of the gas flow, in such a way that there is an angle between the direction of gravity and a shortest distance between the counter electrode and emission electrode.

According to a further aspect of the present invention, which can be combined with the preceding aspects and exemplary embodiments, is an electrostatic precipitator for separating liquid and / or solid particles, such as oil particles, from a gas flow, in particular from a blow-by gas of a crankcase ventilation, an internal combustion engine provided. The electrostatic precipitator works essentially according to the following principle: release of electrical charges, especially electrons; Charging the particles in an electric field; Transport of the electrically charged particles to an opposite pole; Discharging the charged particles at the opposite pole; and removing the particles from the opposite pole. Alternatively or additionally it can be provided that

The electrostatic precipitator according to the invention comprises an emission electrode with an elongated shaft and a counter electrode. The counter electrode and the emission electrode can be insulated from one another and / or each can be made from one piece. The emission electrode, also called a spray electrode, essentially serves to emit, preferably negatively charged, particles. The counter electrode, also called the collecting electrode, forms the opposite pole. An electrical high voltage can be applied to the emission electrode and the counter electrode, so that an electrical high voltage field can be generated between the emission electrode and the counter electrode. For example, the high voltage is in the range of 8-20 kV, preferably in the range of 10-16 kV or in the range of 11-14 kV.

The shaft can have a preferably constant, essentially cylindrical cross section with a shaft diameter of at least 0.2 millimeters and at most 1 millimeter. For example, the shaft diameter is approximately 0.4 millimeters. Alternatively or additionally it can be provided that the shaft protrudes from the carrier by at least 0.5 millimeters and preferably 8 millimeters. The carrier can have an electrical conductivity of less than 10 ^-8 S * cm ^-1 . The carrier can furthermore be made of a fluid-impermeable material, so that it is ensured in particular that fluid particles of the gas stream flowing through the electrostatic precipitator cannot leave the separation space via the carrier.

Preferred embodiments are given in the subclaims.

• 1 eine Prinzipskizze eines Beispiels zur Entstehung von Blow-By-Gasen und zur Einbausituation von erfindungsgemäßen Elektroabscheidern;
• 2 eine perspektivische Ansicht einer ersten Ausführungsform eines erfindungsgemäßen Elektroabscheiders;
• 3 eine perspektivische Ansicht eines Ausschnitts des Elektroabscheiders gemäß 2;
• 4 eine Detailseitenansicht des Elektroabscheiders gemäß den 2 und 3;
• 5 eine perspektivische Ansicht einer weiteren beispielhaften Ausführung eines erfindungsgemäßen Elektroabscheiders;
• 6 eine perspektivische Ansicht eines Ausschnitts des Elektroabscheiders gemäß 5;
• 7 eine Detailseitenansicht des Elektroabscheiders gemäß den 5 und 6;
• 8 eine perspektivische Ansicht einer weiteren Ausführungsform eines erfindungsgemäßen Elektroabscheiders;
• 9 eine perspektivische Ansicht eines Ausschnitts des Elektroabscheiders gemäß 8;
• 10 eine Detailseitenansicht des Elektroabscheiders gemäß den 8 bis 9;
• 11 eine schematische Stirnansicht eines Ausschnitts eines erfindungsgemäßen Elektroabscheiders;
• 12 eine perspektivische Ansicht einer weiteren Ausführungsform eines erfindungsgemäßen Elektroabscheiders; und
• 13 eine perspektivische Ansicht eines Ausschnitts des Elektroabscheiders gemäß 12.

In the following, further properties, features and advantages of the invention will become clear by means of a description of preferred embodiments of the invention with reference to the accompanying exemplary drawings, in which:

• 1 a schematic diagram of an example of the formation of blow-by gases and the installation situation of electrostatic precipitators according to the invention;
• 2 a perspective view of a first embodiment of an electrostatic precipitator according to the invention;
• 3rd a perspective view of a section of the electrostatic precipitator according to 2 ;
• 4th a detail side view of the electrostatic precipitator according to FIGS 2 and 3rd ;
• 5 a perspective view of a further exemplary embodiment of an electrostatic precipitator according to the invention;
• 6th a perspective view of a section of the electrostatic precipitator according to 5 ;
• 7th a detail side view of the electrostatic precipitator according to FIGS 5 and 6th ;
• 8th a perspective view of a further embodiment of an electrostatic precipitator according to the invention;
• 9 a perspective view of a section of the electrostatic precipitator according to 8th ;
• 10 a detail side view of the electrostatic precipitator according to FIGS 8th to 9 ;
• 11 a schematic end view of a section of an electric separator according to the invention;
• 12th a perspective view of a further embodiment of an electrostatic precipitator according to the invention; and
• 13th a perspective view of a section of the electrostatic precipitator according to 12th .

In the following description of exemplary embodiments, an inventive electrostatic precipitator for separating liquid and / or solid particles from a gas flow, in particular from a blow-by gas of a crankcase ventilation of an internal combustion engine, is generally given the reference number 1 Mistake.

1 shows a schematic basic sketch for the installation situation of electrostatic precipitators according to the invention 1 in a crankcase ventilation system 100 . The crankcase ventilation system 100 includes a crankcase 103 with a flow outlet opening 105 , through the blow-by gas from the crankcase 103 can exit, and one with the flow outlet opening 105 fluidically connected electrostatic precipitator according to the invention 1 . As in 1 can be seen, the fluidic connection between the electrostatic precipitator 1 and flow outlet opening 105 via a pipeline system, such as an outlet pipe 107 , take place, which the flow outlet opening 105 of the crankcase 103 with a flow inlet opening 109 of the electrostatic precipitator 1 connects. Alternatively, the electrostatic precipitator 1 so on the crankcase 103 be mounted (not shown) that the flow inlet opening 109 the flow outlet opening 105 of the crankcase 103 corresponds to. Using the arrow with the reference number 111 is indicated that blow-by gas from the crankcase 103 in the electrostatic precipitator 1 can flow.

Also shows 1 an example of the development of blow-by gas and the general installation situation of the electrostatic precipitator 1 . It's an internal combustion engine 113 shown, the one with a fresh air supply 115 , an exhaust gas discharge 117 and the crankcase ventilation system 100 is fluidly coupled. The internal combustion engine 1 includes a cylinder head 119 , a cylinder 121 and the crankcase 103 . In the cylinder 121 becomes a piston 123 axially guided, the one displacement 125 opposite a crankcase interior 127 delimits. To seal the displacement 125 opposite the crankcase interior 127 are not shown sealing rings between pistons 123 and cylinder 122 are provided. Nevertheless, combustion gases and / or unburned gases flow between pistons 123 and cylinder 121 of the cubic capacity 125 into the crankcase interior 127 . The resulting gas flow is also referred to as blow-by gas flow and, in addition to air and oil, also includes combustion gases and unburned fuel components.

To an increase in pressure in the crankcase 103 to prevent the gas flow through the crankcase ventilation 100 from the crankcase 103 discharged and fed to the fresh air supply. This includes the crankcase ventilation 100 in particular the fluid coupling of the flow outlet opening 105 and the flow inlet opening 109 of the electrostatic precipitator 1 . The electrostatic precipitator 1 is also via a return line 129 for allowing separated particles, such as oil, to flow back fluidly with the crankcase 103 connected. In particular, the return line connects 129 a return outlet 131 of the electrostatic precipitator 1 fluidal with a return inlet 133 of the crankcase 103 . Downstream of the electrostatic precipitator 1 also connects a return line 135 the electrostatic precipitator 1 fluidal with the fresh air supply 115 to the fresh air supply 115 to supply a gas stream which has been cleaned of particles. The resulting fresh air flow 137 that is a mixture of that from the electrostatic precipitator 1 coming cleaned gas stream and one sucked in from the environment and by means of an air filter 139 can be purified gas flow is via a compressor wheel 141 compressed and via an intercooler 143 as well as a throttle valve 145 the internal combustion engine 113 over the cylinder head 119 fed. Combustion gases not between pistons 123 and cylinder 121 into the crankcase 103 arrive as exhaust gas 147 Passed through an exhaust gas discharge (not shown) into the environment.

It should be clear that the installation situation of the electrostatic precipitator according to the invention 1 in the case of use as an oil separator in the combustion engine, do not rely on the in 1 installation situation shown and also not for use in a crankcase ventilation system 100 is limited. For example, the electrostatic precipitator can also be used to separate particles from gas streams that flow between cylinders 121 and cylinder head 119 and / or between the cylinder head 119 and cylinder head cover from the internal combustion engine 113 step out.

Another possible area of application is the supply of fresh air 115 and / or in the exhaust gas discharge 117 , in particular about the compressor wheel 141 and the shaft connecting the turbine wheel, not shown, can be fluidly coupled to one another.

Based on 2 to 13th are exemplary embodiments of electrostatic precipitators according to the invention 1 explained in more detail.

The electrostatic precipitator 1 is according to a first embodiment in FIG 2 to 4th pictured. The electrostatic precipitator 1 includes a separation space 3rd defining or limiting housing 5 that one floor 7th , on the floor 7th opposite roof 9 as well as two opposite, each the bottom 7th with the roof 9 connecting side walls 11 , 13th owns. Via an entry opening 15th a gas flow arrives 17th , For example, blow-by gas from a crankcase ventilation system into the separation chamber 3rd . The entrance opening 15th opposite is the outlet opening 19th arranged over which the gas flow 17th , which is then used as a purified gas stream 21 is referred to, the separation space 3rd can leave again. That the separation room 3rd limiting housing 5 is not limited to a particular geometry, according to the 2 to 10 however, formed as a hollow pipe section with a substantially rectangular cross section.

The electrostatic precipitator 1 further comprises a plurality of emission electrodes 23 and several counter electrodes 25th . According to the embodiments 1 includes the electrostatic precipitator 1 six counter electrodes 25th . At the emission electrodes 23 and the counter electrodes 25th an electrical high voltage can be applied or applied so that between the emission electrodes 23 and the counter electrodes 25th an electrical high-voltage field can be generated or generated. In 2 it can be seen that the counter electrodes 25th are implemented in sections as essentially straight rods or tubes, the direction of longitudinal extent of which is indicated by the reference number Q , transversely, in particular perpendicular, to the main flow direction S. of the entering and flowing gas stream 17th is oriented. The counter electrodes 25th are designed essentially the same and in the direction of flow S. arranged at a distance from one another. On the rod section which extends essentially in a straight line 29 of the counter electrodes 25th closes at both ends, preferably in one piece with the rod section 29 manufactured curved section 31 on, the rod section 29 essentially free of edges, protrusions and / or steps into the curved section 31 transforms. The curve section 31 eventually flows into the ground 7th of the housing 5 . In 2 it can also be seen that the curved section 31 forms an angle of curvature of over 90 °, so that a connection point 33 the counter electrode 25th with the ground 7th with respect to the direction of longitudinal extension of the counter electrode 25th in the transverse direction Q inwards with respect to an outermost point of curvature 35 of the curve portion 31 is offset.

The counter electrode 25th includes one of the emission electrodes 23 facing receiver surface 37 for receiving electrically charged particles from the gas flow 17th . The receiver surface 37 is in the direction of the emission electrodes 23 arched and goes all around continuously into one of the emission electrodes 23 remote separation surface 39 above. The preferred shape of the counter electrodes 25th as essentially fully cylindrical rods or tubes, it allows the separated particles, which are on the receiver surface 37 hit the receiver surface 37 can leave everywhere unobstructed, in particular can run off or drip off and to the separation surface 39 can get. The counter electrodes 25th extend with a substantially constant cross section and one in the direction of the emission electrodes 23 curved receiver surface 37 transverse to the direction of flow S. in the direction of flow Q and with one substantially of the emission electrodes 23 remote separation surface 39 , which is inclined opposite to the receiver surface with preferably the same radius of curvature.

In 3rd it can be seen that two groups of three counter-electrodes each arranged at a constant distance from one another 25th are provided. The two groups of counter electrodes 25th is each a group of emission electrodes 23 assigned. The emission electrodes 23 have a substantially elongated, needle-like shape and extend from the housing roof 9 essentially straight and in the direction of gravity G in the separation room 3rd and in the direction of the counter electrodes 25th . The two groups of emission electrodes 23 each have two arrays of emission electrodes 23 in a row across the direction of flow S. of the guest stream 117 are arranged and spaced from one another. Between the respective groups of emission electrodes 23 or counter electrodes 25th is always a free space 41 formed in the direction of flow S. considered is dimensioned larger than a respective distance between two adjacent counter-electrodes 25th or emission electrode rows 23 .

In 4th showing a side view of the electrostatic precipitator 1 according to the 2 and 3rd illustrates another aspect of the present invention is illustrated. First of all, it can be seen that the individual rod-shaped or tubular counter-electrodes are located 25th essentially completely straight in the transverse direction Q extend. It can also be seen that the emission electrodes 23 a substantially cylindrical, elongated shaft 43 own, each in a funnel-shaped or conical tip 45 passes, at which electrons the emission electrodes 23 leave. Which is in the transverse direction Q forming rows of emission electrodes 23 are each such with respect to the counter-electrodes 25th positioned and in the direction of flow S. with respect to the counter electrodes 25th offset that an angle α between the direction of gravity G and a shortest distance denoted by the reference number a is indicated between the counter electrode 25th and emission electrode 23 consists. The emission electrode needle tips 45 thus each point in one between two adjacent counter-electrodes 25th existing space. Through the in the direction of flow S. provided offset between emission electrodes 23 and counter electrodes 25th forms a so-called diarrhea sector between every two adjacent counter electrodes 25th from, in which from the emission electrodes 23 dissolving deposits can get past the counter electrodes.

Based on 5 to 7th is another exemplary embodiment of an electrostatic precipitator according to the invention 1 explained. Identical or similar components are provided with the same or similar reference numerals. In order to avoid repetition, reference is only made to the comparison with the first embodiment according to FIGS 2 to 4th resulting differences.

The main difference of the embodiment according to 5 to 7th lies in the structure of the counter electrodes 25th . As in the embodiment according to FIGS 2 to 4th the counter electrodes extend 25th with a substantially constant cross-section and one in the direction of the emission electrodes 23 curved receiver surface 37 transverse to the direction of flow S. in the direction of flow Q and with one substantially of the emission electrodes 23 remote separation surface 39 . The counter electrodes 25th the embodiment according to 5 to 7th however, do not have a curved portion at the ends 31 that for the formation of a ground contact or connection point 33 with the ground 7th is bent or curved. In particular, in 5 it can be seen that the essentially fully cylindrical rod-shaped or tubular counter-electrodes 25th are rounded at both opposite ends, with hemispherical end sections 47 are formed. This means the tube sections 29 Edge, protrusion and / or step-free into the ball end sections 47 pass over. In this case, a radius of curvature of the end portion of the curvature 47 essentially the radius of curvature of the tube section 29 the counter electrode 25th correspond.

Furthermore, the counter electrodes each have two feet 49 on, extending from an underside of the counter electrodes 25th , that is, from the separation surfaces 39 , essentially in the direction of gravity G towards the bottom 7th of the housing 5 extend and realize a ground support or ground contact. The embodiments according to 2 to 4th or. 5 to 7th is common that the counter electrodes 25th , especially their tube sections 29 , at a certain distance from the ground 7th are arranged. When executing according to the 2 to 4th this is made possible by the bent-over curved sections 31 realized, which thus realize the floor support at the ends. When executing according to the 5 to 7th this is done through the feet 49 realized and about a height of the feet 49 controlled. In addition, the description regarding the execution of the 2 to 4th to get expelled.

Based on 8th to 10 Another exemplary embodiment is described. Identical or similar components are provided with the same or similar reference numerals. In order to avoid repetition, it is essentially referred to in relation to the preceding statements according to FIGS 1 to 7th resulting differences.

The main difference of the embodiment according to 8th to 10 lies in the design of the counter electrodes 25th . Unlike the embodiments according to FIGS 2 to 7th where the counter electrodes 25th a group of counter electrodes 25th are manufactured as separate components, combine the counter electrodes 25th the 8th to 10 by means of a serpentine structure, three counter-electrode segments, each through the essentially fully cylindrical tube sections 29 are formed in one component; that is, the serpentine counter-electrodes 25th are made from one piece. To do this, the counter electrodes 25th an uprising foot close to the flow inlet 51 on, which has a substantially cylindrical cross-section and continuously, without edges, protrusions and interruptions in an angle piece 53 merges, which again without interruption, in particular without edges and / or protrusions, into a tube section 29 the counter electrode 25th passes, which is in the transverse direction Q extends as described in relation to the previous embodiments. At the opposite end of the tube section 29 regarding the uprising foot 51 the tube section opens 29 in a U-piece 55 , by means of which a reversal by 180 ° is realized, so that a tube section is again 29 which results in the transverse direction Q through the separation room 3rd extends. In this respect, the counter-electrodes have an essentially identical structure 25th with the difference that two adjacent tube sections 29 , which are essentially relevant for the separation of particles, by means of a U-piece 55 are connected to one another and are therefore not separate counter-electrode elements 25th acts.

As in particular in 8th can be seen are the emission electrodes 23 such with regard to the serpentine counter-electrode groups 25th arranged that the emission electrodes 23 regarding the transverse direction Q to the U-pieces 55 are offset, so that also with respect to the transverse direction Q considered outermost emission electrodes 23 and the U-pieces 55 an angle β regarding the direction of gravity G and a shortest distance between emission electrode tips 45 and U-piece 55 consists.

One to the upstream pipe section 29 subsequent central tube section 29 opens at one of its ends in turn into a 180 ° U-piece 55, so that starting from the U-piece 55 again a straight downstream tube section with the same cross section and orientation 29 results. This opens with respect to the transverse direction Q at the level of the U-piece 55 into an elbow 53 , whereby a transition is realized again without interruption, which finally turns into a riot 51 transforms. The downstream group of counter electrodes 25th is again through an identical serpentine counter-electrode unit 25th educated. The upstream counter electrode element 25th the downstream counter-electrode group is arranged with respect to the upstream counter-electrode group in such a way that the upstream contact foot 51 of the downstream counter electrode group on the same side with respect to the transverse direction Q like the downstream riot 51 of the upstream counter electrode group is positioned. In addition, the description in relation to the statements according to the 2 to 7th to get expelled.

Based on 11 is schematically applied to the electrical high voltage between the emission electrode 23 and counter electrode 25th received. The application of an electrical high voltage is shown schematically through the two poles 57 , 59 indicated. The way in which electrodeposition works is discussed in more detail below. Because of the high electrical voltage that flows across the poles 57 , 59 is applied, a high-voltage field is formed between the emission electrode 23 and counter electrode 25th out. Thereby the electrostatic precipitator 1 preferably operated below the breakdown or flashover voltage. For example, the electrostatic precipitator 1 be operated in such a way that, as in 11 is shown, electrons from the emission electrode 23 emerge and interact with the surrounding gas molecules, creating a negative corona, which in 11 by means of the reference number 61 is indicated, results. Free electrons present in the gas become the corona in the electric field 61 strongly accelerated, so that a gas discharge can occur. When they hit gas molecules, further electrons can be split off or attach to the gas molecules.

The negative charges then move with the formation of an umbrella-like or cone-like ionization region 63 (also called ion cloud) forming curtain in the direction of the emission electrodes 23 oppositely charged counter electrons 25th . The curtain-like ionization area 63 settles down as it does in 11 can be seen, essentially completely circumferentially around the receiver surface 37 , which of the emission electrode 23 is facing. The negatively charged particles from the gas flow migrate across the direction of flow S. of the gas flow in the direction of the receiver surface 37 to which they are attracted, to which they strike and to which they release their cargo again. The liquid particles, such as oil particles, then flow from the receiver surface 37 because of its concave shape and can then be removed from the counter electrode 25th drip off and / or continue along the outside of the counter electrode 25th up to the separation area 39 migrate away from the emission electrode and in the direction away from the emission electrode 23 is curved, with the same radius of curvature as the receiver surface 37 . The cross-section has the counter electrode 25th according to the exemplary embodiments, a circular shape. At the separation surface 39 are schematic particles 65 depicted that were deposited by the gas stream and along the receiver surface 37 up to the separation area 39 on the outside of the counter electrode 25th hiked along.

In the 12th and 13th is a further exemplary embodiment of an electrostatic precipitator according to the invention 1 shown. The same or similar components are provided with the same or similar reference numbers.

The electrostatic precipitator according to 12th to 13th includes a housing 67 , which is an inlet duct or inlet duct section 69 for introducing a gas stream 17th in the electrostatic precipitator 1 having. The insertion canal 69 is formed as a substantially inner cylindrical pipe section in which a flow direction of the raw gas flow 17th substantially perpendicular to the main flow S. within the separation room 3rd of the electrostatic precipitator 1 is oriented. The housing also includes 67 another, essentially identical to the channel section 69 formed outlet channel section 73 , via which the cleaned gas flow from the electrostatic precipitator 1 can be discharged. The direction of flow in 12th is only to be understood as an example. It is also possible that the flow over the with the reference number 73 designated channel section and inserted over the with the reference number 69 designated channel section is discharged. The case 67 can, for example, consist of two housing halves to be fastened to one another 75 and 77 be formed, the upper half of the housing 75 the cover and the lower half of the housing 77 forms the ground. Inside the separation room 3rd of the electrostatic precipitator 1 is a counter electrode designed as a flat plate 25th on the bottom housing part 77 arranged. The plate-like counter electrode 25th is with respect to the surrounding inner surface 79 of the bottom housing part 77 arranged elevated. From the gas stream separated particles are released from the counter electrode 25th attracted and can flow or drip off from this and by means of a particle or fluid drain connected to a bypass channel (not shown) 81 be discharged and, for example, fed back into a corresponding fluid circuit. For example, when it comes to oil particles, the separated oil particles can be returned to the oil circuit in the crankcase 103 be guided.

The plate-like counter electrode 25th opposite is an emission electrode field 23 provided, which on an inside 83 of the cover housing part 75 is arranged. The individual emission electrodes 23 extend from the inside 83 essentially in the direction of gravity G in the direction of the plate counter-electrode 25th . As in particular in 13th can be seen, has the emission electrode field 23 four essentially in the transverse direction Q transverse to the direction of flow S. extending rows of emission electrodes 23 , wherein the direction of extension of the individual rows is essentially parallel to one another. Looking at the 12th and 13th , in which only the upper part of the housing 75 is shown for simplified illustration, it can be seen that the flat extension of the flat plate-like counter-electrode 25th is dimensioned larger than an outer circumferential dimension of the emission electrode field 23 .

According to the detail view XIII in 13th it is indicated that the individual emission electrodes 23 an emission electrode row are arranged at a regular, constant distance from one another. For example, it can be provided that an emission electrode length 1 is at least 2 mm and preferably at most 8 mm. Furthermore, it can be provided that a distance x two adjacent emission electrodes 23 is in the range from 3 mm to preferably 15 mm, at least with respect to one row of emission electrodes. Especially in 13th it can also be seen that the emission electrodes 23 two adjacent rows of emission electrodes in the transverse direction Q are arranged offset from one another, so that, for example, one emission electrode each 23 halfway between two adjacent emission electrodes 23 an upstream emission electrode row is positioned. For example, the emission electrodes 23 be held by a carrier with an electrical conductivity of less than 10 ^-8 S * cm ^-1 . The carrier 85 can for example be the bottom 83 of the upper part of the housing 75 form. For example, the carrier includes 85 Plastic, preferably thermosetting plastic and / or potting compound, such as epoxy resin or silicone. The upper part of the housing 75 has on an inside, on which also the carrier 85 is arranged adjacent to the carrier 85 Flow guides 87 , 89 at which the fluid flow is deflected. For example, the flow guidance 87 the inlet duct section 69 and the flow guidance 89 the outlet duct section 73 assigned.

The features disclosed in the above description, the figures and the claims can be important both individually and in any combination for realizing the invention in the various configurations.

List of reference symbols

1

Electrostatic precipitator

3

Separation room

5

casing

7th

Bottom housing part

9

Roof housing part

11, 13

Side wall

15th

Inlet opening

17th

Gas flow

19th

Outlet opening

21

Gas flow

23

Emission electrode

25th

Counter electrode

29

Rod section

31

Curve section

33

Connection point

35

Point of curvature

37

Receiver surface

39

Separation area

41

free space

43

shaft

45

top

47

End section

49

foot

51

Uprising

53

Elbow

55

U-piece

57, 59

pole

61

corona

63

Ionization range

65

Particles

67

casing

73

Outlet duct section

69

Inlet duct section

75, 77

Housing half

79

Inner surface

81

Particle or fluid drain

83

inside

85

carrier

87, 89

Flow guidance

100

Crankcase ventilation system

103

Crankcase

105

Flow outlet opening

107

Outlet line

109

Flow inlet opening

111

Blow-by gas flow

113

Internal combustion engine

115

Fresh air supply

117

Exhaust gas removal

119

Cylinder head

121

cylinder

123

piston

125

Displacement

127

Crankcase interior

129

Return line

131

Return outlet

133

Return inlet

135

Return line

137

Fresh air flow

139

Air filter

141

Compressor wheel

143

Intercooler

145

throttle

147

Exhaust gas

α, β

angle

a

shortest distance

l

length

x

distance

G

Direction of gravity

S.

Direction of flow

Q

Transverse direction

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• WO 2016/147127 A1 [0003]
• DE 29809320 U1 [0005]

Claims (9)

Electro separator (1) for separating liquid and / or solid particles from a gas flow, in particular from a blow-by gas from a crankcase ventilation, of an internal combustion engine, comprising: - An emission electrode (23) and a counter electrode (25) to which a high electrical voltage can be applied so that a high voltage electrical field can be generated between the emission electrode (23) and the counter electrode (25); wherein a receiver surface (37) of the counterelectrode (25) facing the emission electrode (23) is at least partially provided with an anti-stick layer and the anti-stick layer is at least partially offset with electrically conductive particles. Electrostatic precipitator (1) Claim 1 , the receiver surface (37) preferably merging without steps, edges and / or protrusions into a separation surface (39) facing away from the emission electrode (23), which has a lower non-stick effect than the receiver surface (37) and / or which is essentially free of a non-stick layer. Electrostatic precipitator (1) after one of the Claims 1 to 2 , the non-stick layer comprising plastic, preferably fluorine-based plastic, in particular PTFE, FEP and / or PFA, and / or a thermoplastic plastic, preferably PEEK. Electrostatic precipitator (1) after one of the Claims 1 to 3rd , the non-stick layer having a layer thickness in the range from 1 µm to 100 µm. Electrostatic precipitator (1) after one of the Claims 1 to 4th , wherein the electrically conductive particles consist of a metal or graphite. Electro separator (1), in particular according to one of the preceding claims, for separating liquid and / or solid particles from a gas flow, in particular from a blow-by gas of a crankcase ventilation, of an internal combustion engine, comprising: - An emission electrode (23) and a counter electrode, to which a high electrical voltage can be applied, so that an electrical high voltage field can be generated between the emission electrode (23) and the counter electrode (25); wherein a receiver surface (37) of the counter-electrode (25) facing the emission electrode (23) is provided at least in some areas with an anti-stick layer which has a layer thickness of less than 200 nm. Electrostatic precipitator (1) Claim 6 The non-stick layer as an electrical insulator with an electrical conductivity of less than 10 ^-8 S * cm ^-1 and / or a specific resistance of at least 10 ⁷ Ω * cm. Electrostatic precipitator (1) after one of the Claims 6 to 7th wherein the non-stick layer, in particular the electrical insulator, comprises a substance with a silicon-based chemical compound, in particular silicon dioxide or fluorosilane. Electrostatic precipitator (1) after one of the Claims 6 to 8th wherein the anti-stick layer is applied to the counter-electrode (25) by spraying or spraying the counter-electrode (25) or by immersing the counter-electrode (25) in a non-stick-layer bath.

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