Patent Application
20250025889
This application claims priority from German Patent Application No. DE 102023206819.2, filed on Jul. 18, 2023, the entirety of which is hereby fully incorporated by reference herein.
The present invention relates to an air filtering process for a heating, ventilation, and air conditioning system in a motor vehicle. The invention also relates to a heating, ventilation, and air conditioning system for a motor vehicle according to the preamble of claim 6.
A heating, ventilation, and air conditioning system is frequently referred to as an HVAC system.
An HVAC system of this type is disclosed in EP 3 056 364 B1, and contains an ionizer for generating a corona discharge, which has at least one electrically polarized discharge electrode and at least one oppositely polarized counter electrode. The HVAC system also contains a particle filter for removing particles from an air flow. Lastly, the HVAC system contains an flow path for the air that leads to a vehicle interior and passes through the ionizer and the particle filter. The ionizer is upstream of the particle filter in the flow path. In existing HVAC systems, the counter electrode is cylindrical, and the discharge electrode is concentric to the counter electrode, and parallel to the longitudinal central axis thereof.
Other HVAC systems using ionization are disclosed in EP 3 488 933 A1, KR 10-2205159 B1, US 2021/0 021 107 A1, WO 2020/263171 A1, and WO 2021/226639 A2.
These HVAC systems are used in particular when there is comparatively little installation space for the particle filter, while at the same time, a high level of filtration for larger quantities of air is desired over a longer time period. A high filtration level can be obtained with smaller pores in the particle filter. Smaller pores result in higher flow resistance, however. To compensate for this, the surface area through which air can flow can be increased. The increase in surface area is limited by the available installation space. In particular where there are high levels of particulate matter, a particle filter with sufficiently small pores can only achieve the desired level of filtration for the amount of air that is required for a short time, because it quickly becomes clogged, and the flow resistance increases to unacceptable levels. By using particle filters that have been electrostatically charged in the production process, fine particles can be filtered out of the air, even with larger pores, if these particles have been ionized. The particles bond through electrostatic attraction to the charged filter material. The particles are ionized by an ionizer. An electrostatic field, referred to as a corona discharge field, is generated for this between a discharge electrode and a counter electrode. The discharge electrode preferably has a negative polarity, while the counter electrode then has a positive polarity, or is grounded. The corona discharge is generated at the sharp tips of the negative discharge electrode, consequently generating a large number of electrons moving at high speed toward the opposing electrodes. When these electrons collide with gas molecules in the air flow, either more electrons are released, or the electrons bond with the gas molecules. In the first case, new electrons are released, and positive gas ions are formed, and in the second case, negative gas ions are formed. This gas ionization can also be obtained with reversed polarity, i.e. a positive discharge electrode and negative counter electrode.
The particles are charged by the gas ions, starting when the particles enter the corona discharge space in the discharge flow. The particles are charged when gas ions bond with the particles by colliding therewith. The charging process is obtained with field and diffusion charging.
In practice, the original electrostatic charge of the particle filter obtained in the production process diminishes over time, such that the filtration effect of the particle filter diminishes significantly after a short time. To compensate for this, the replacement intervals for the particle filter can be significantly shortened, but this increases costs substantially.
The problem addressed by the present invention is to create an improved or at least different embodiment for an HVAC system of the above type for an air filtering process, which is distinguished in particular by a high level of filtration of large air quantities over a long service life.
This problem is solved according to the invention by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.
The air filtering process according to the invention for an HVAC system in a motor vehicle is based on the general concept of polarizing the particle filter with an electric field in order to electrostatically charge it. The electric field needed for this according the invention is generated with an ionizer. The already existing ionizer can therefore be used for an additional function. The polarization of the particle filter results in an electrostatic charging of the particle filter, thus improving the filtration effect on particles. In particular, the electrostatic charging can restore the electrostatic charge obtained in the production process. In other words, the polarization of the particle filter results in a restoration thereof.
In an advantageous embodiment, the particle filter can have at least one electrically conductive layer to which on an electric potential opposite that of the discharge electrode is applied, such that an electric field is generated between the ionizer and the particle filter when the ionizer is in operation. The particle filter can be ionized by the electric field between the ionizer and the particle filter. This electric field can therefore also be referred to as a polarization field. The electrostatic charge of the particle filter is basically restored by the polarization thereof. Consequently, a basically constant filtration level can be obtained over the intended service life of the particle filter, even when dealing with large air quantities. The respective potential can be provided at the electrically conductive layer of the particle filter by connecting this layer with a counter-potential that is opposite that of the discharge electrode.
In one advantageous embodiment, the conductive layer is only connected to the counter-potential until the polarization of the particle filter reaches a predefined threshold. Once this polarization threshold has been reached, the conductive layer in the particle filter is disconnected from the counter-potential. The conductive layer could also only be connected to the counter-potential for a predetermined polarization time. Once this time has elapsed, the conductive layer in the particle filter is disconnected from the counter-potential. In this case, the time is monitored. There is therefore no need to monitor the polarization level. These measures are based on the fact that after the particle filter has been polarized, the electrostatic charge obtained therewith diminishes slowly when the HVAC system is in use, specifically due to the particles filtered out of the air flow. The disconnection of the counter-potential removes the electric field between the ionizer and the particle filter, such that the ionizer consumes less electricity. This results in an energy-efficient operation of the HVAC system.
While generating the electric field for polarizing the particle filter, the ionizer consumes more electricity. This generates ozone in the air flow. When the conductive layer is disconnected from the counter-potential, less electricity is used by the ionizer, resulting in less ozone being generated, thus reducing the ozone levels in the vehicle interior.
In an advantageous version of the air filtering process, the conductive layer can be disconnected from the counter-potential only until the polarization of the particle filter falls below a predefined depolarization threshold. In other words, the electrostatic charge of the particle filter is monitored. Once this falls below the depolarization threshold, the polarization is resumed to restore the electrostatic charge. This restoration, or polarization, can basically be repeated as often as needed. Once the depolarization threshold has been reached, the conductive layer is reconnected to the counter-potential. The particle filter is then repolarized. Alternatively, the conductive layer can only be disconnected from the counter-potential until a predefined depolarization time has elapsed. After this depolarization time has elapsed, the conductive layer is reconnected to the counter-potential. In this case, time is monitored. There is no need to monitor the polarization.
The polarization time and/or depolarization time are dependent on the application for which the particle filter is intended, in which certain conditions must be take into account, e.g. the size of the particle filter, the intended filtration effect, and/or the amount of air and particulate matter where the particle filter is to be used.
An embodiment in which the discharge electrode is positive and the counter electrode is negative is fundamentally advantageous. An embodiment in which the discharge electrode is negative and the counter electrode is positive is preferred, however. This results in a particularly efficient ionization.
In one advantageous embodiment, the counter electrode can be permanently connected to the counter-potential, and the conductive layer in the particle filter is connected to the counter electrode to connect it to the counter-potential. This is a particularly simple design.
The HVAC system according to the invention is based on the general concept of equipping the discharge electrodes with numerous needles that point in or against the direction in which the air flows. These needles protrude from a needle substrate toward or against the flow direction. The discharge electrodes and their dedicated counter electrodes are spaced apart across the flow path.
In an advantageous embodiment, the discharge electrodes can have numerous needles on the upstream side, extending in the flow direction and away from the particle filter.
The tips thereof are thus facing away from the particle filter.
In one advantageous embodiment, the discharge electrodes can have numerous needles on the downstream side, extending in the flow direction and toward the particle filter. With downstream needles pointing toward the particle filter, the tips thereof face the particle filter. Although an embodiment in which the discharge electrodes have upstream and downstream needles is preferred, embodiments lacking either the downstream or upstream needles are also possible.
If there are numerous upstream and downstream needles, a configuration in which the upstream needles on an upstream side of the needle substrate are spaced apart evenly is preferred. The downstream needles on the downstream side of the needle substrate can also be spaced apart evenly, at the same spacing as the upstream needles. It may also be advantageous if the upstream needles are offset to the downstream needles, such that they are each located in the middle, between two downstream needles.
In an advantageous embodiment, the counter electrode can form a plate, preferably a flat plate. The plate-shaped counter electrode can be parallel to the discharge electrode. The plate is flat, and the thickness thereof is less than the length and width. The plate can be placed in the air flow such that the width thereof is parallel to the flow direction of the air, and the length and thickness are transverse thereto. Consequently, the air only flows against a narrow edge of the counter electrode. The discharge electrodes and dedicated counter electrodes can also extend in straight lines, preferably transverse to the flow direction of the air. This structure results in an efficient generation of the corona discharge in order to effectively ionize the particles in the air flow. Furthermore, this configuration is relatively small in relation to the flow direction.
In an advantageous embodiment, there can be at least one conductive layer in the particle filter, which can be connected to a counter-potential that is opposite the potential of the discharge electrode. This provides an electrical connection for the HVAC system with which the conductive layer is connected to the counter-potential. In the simplest case, this can be obtained with the ground wire connected to the ground for the ionizer.
In the present context, a “configuration” means the same as a “design” and/or “programing,” such that the formulation “configured such that” has the same meaning as “designed and/or programmed such that.”
An embodiment in which the electrical connection can be switched on and off is advantageous. This allows for the conductive layer to be connected and disconnected from the counter-potential as needed. The conductive layer of the particle filter connected to the counter-potential can thus be polarized when the ionizer is in use in order to restore its electrostatic charge. When it has been sufficiently charged, further polarization can be stopped by disconnecting it from the counter-potential, in order to conserve electricity. The switching capability of the connection can be obtained with an electromechanical or electronic switch, for example.
An embodiment in which the HVAC system contains a control unit that is configured to execute the above air filtering process when the HVAC system is in use is particularly advantageous. In other words, the control unit controls the components of the HVAC system that can be controlled, specifically the ionizer and the switchable connection, to execute the above air filtering process.
The dielectric layer of the particle filter can contain or be made of a nonwoven sheet. These are normally made of a synthetic and are therefore dielectric. Nonwoven sheets can be produced with a melt blowing process. The particle filtering layer determines the pore size of the particle filter, and is impermeable to particles that are larger than the pore size.
In another embodiment, the conductive layer of the particle filter can form an adsorption filtering layer, containing or made of activated carbon. Because of the abutting activated carbon particles, which are conductive, the adsorption filtering layer as a whole is also conductive, and can be used to form the polarizing electric field, because it is grounded. The adsorption filtering layer filters through adsorption, which functions in particular for gas molecules. The activated carbon particles can bond to a nonwoven layer, or be contained between two nonwoven layers.
Instead of, or in addition to the adsorption filtering layer, the conductive layer in the particle filter can also form a grid structure, containing or made of conductive wires, fibers, or filaments. Unlike a particle filter layer, or an adsorption filtering layer, the grid structure has no significant filtration effect.
It is advantageous when the dielectric layer lies on the conductive layer and is therefore in contact therewith. In particular, the conductive layer extends over the entire dielectric layer. This results in the electric field generated by the grounding of the conductive layer also acting on the dielectric layer, such that the dielectric layer can also be polarized, or electrostatically charged.
A particularly advantageous configuration has proven to be one in which the dielectric layer in the particle filter is upstream of the conductive layer. This results in the electrons and/or ions in the electric field with which the charging and polarization of the particle filter is obtained colliding with the dielectric layer on the way to the conductive layer, and remaining there to obtain the desired polarization.
Other important features and advantages of the invention can be derived from the dependent claims, the drawings, and the descriptions of the drawings.
It is understood that the features specified above and explained below can be used not only in the given combinations, but also in other combinations or in and of themselves, without abandoning the scope of the invention. The components of a higher order unit, e.g. a device, apparatus, or assembly, that are indicated individually, can form separate components of this unit, or integral parts thereof, even if otherwise indicated in the drawings.
Preferred exemplary embodiments of the invention are shown in the drawings, and shall be explained in greater detail below, in which the same reference symbols are used for the same, similar, or functionally identical components.
Therein, schematically:
The HVAC system 1 for a motor vehicle (not shown) in
The discharge electrode 6, which can also be referred to as an emitter electrode, is connected to a high voltage source 8, which provides a DC current of 5 kV to 10 KV, preferably approx. 7 kV. The counter electrodes 7 are connected to a counter-potential 9 with the opposite polarity of the discharge electrode. In this case, the discharge electrodes 6 have a negative polarity, and the dedicated counter electrodes 7 have a positive polarity. The counter-potential 9 is therefore also positive, as indicated in
The HVAC system 1 also has a particle filter 10 with which particles are removed from an air flow 28, indicated by the wave-shaped arrows in the drawings. The air flow 28 flows in a flow direction 11 when the HVAC system 1 is in use, indicated by line composed of dashes and dots in the drawings. The flow path 12 defines the flow direction 11 for the air. The flow path 12 passes through the ionizer 3 and the particle filter 10. It should be noted that the ionizer 3 is upstream of the particle filter 10 in the flow path 12. The air in the flow path 12 flows into the interior 29 of the vehicle 2, not shown in detail. The air can be fresh air surrounding the vehicle 2 or recirculating air from the vehicle interior 29, or a mixture thereof.
The particle filter 10 in
The HVAC system 1 in
In the air filtering process, an air flow 28 polluted with particles first flows through the ionizer 3 and then the multi-layered particle filter 10 along the flow path 12. The ionizer generates the corona discharge field 4 with the discharge electrodes and dedicated counter electrodes 7 at this point. The air flow 28 that is to be filtered passes through the corona discharge field 4. The particles in the air flow 28 are ionized in the corona discharge field 4. The conductive layer 14 is also connected to the counter-potential 9 by the connection 15 during the air filtering process, such that an electric field 19 is generated between the ionizer 3 and the particle filter 10, which is indicated in
The conductive layer 14 only has to be connected to the counter-potential 9 in the air filtering process until the particle filter reaches a predetermined polarization threshold, and/or until a predetermined polarization time has elapsed. Once the predetermined polarization threshold has been reached, or the predetermined polarization time has elapsed, the conductive layer 14 in the particle filter 10 is disconnected from the counter-potential 9. This can take place by switching off the switch 16. The electrostatic charge of the particle filter 10 then diminishes during the filtration process, due to the particles accumulating thereon. Furthermore, the conductive layer 14 only has to be disconnected from the counter potential 9 in the air filtering process until the polarization of the particle filter 10, i.e. the electrostatic charge, reaches a predetermined depolarization threshold, and/or a predetermined depolarization time has elapsed. Once the predetermined depolarization threshold has been reached, or the depolarization time has elapsed, the conductive layer 14 in the particle filter 10 is reconnected to the counter-potential 9. This can be obtained by switching the switch 16 on. In particular, the conductive layer 14 can first be connected to the counter-potential 9 when the electrostatic charge in the particle filter 10 reaches the predetermined depolarization threshold, and/or when the predetermined depolarization time has elapsed.
As shown in
The needles 20 on the discharge electrodes 6 can be parallel to the flow direction 11. They therefore protrude from the substrate 23 in or against the flow direction. The needles 20 form pins in
The discharge electrodes 6 can have numerous needles 21 on the downstream side, pointing toward the particle filter, as shown in
The discharge electrodes 6 can also have numerous upstream needles 22, which face away from the particle filter 10. In other words, the upstream needles 22 protrude from the substrate 23 away from the particle filter 10. The tips 24 of these upstream needles 22 then also point away from the particle filter 10. The upstream needles 22 are ideally parallel to the flow direction 11 for the air. The upstream needles 22 are mainly used for generating the corona discharge field 4.
When the high voltage potential is applied to the discharge electrodes 6, and the switch 16 is switched off, as shown in
The discharge electrodes 6 can be mounted on the dielectric high voltage insulators, which are part of a housing 34 for the HVAC system 1 shown in
The upstream needles 22 in
The counter electrodes 7 can form plates, which are parallel to the discharge electrodes 6. These counter electrodes 7 can therefore form flat plates. The discharge electrodes 6 and counter electrodes 7 can be straight and parallel to one another, and perpendicular to the flow direction 11 for the air. By way of example, the needle substrates 23 form straight rods. The plate-shaped counter electrodes 7 in
The dielectric layer 13 of the particle filter 10 in
The conductive layer 14 is on the dielectric layer 13 in the particle filter 10, and is therefore in contact therewith. This contact is preferably over the entire surface. In particular, the conductive layer 14 can extend over the entire downstream or upstream surface of the dielectric layer 13. The particle filter 10 in
The HVAC system 1 can also contain a heater for heating the air flow 28, and a cooler for cooling and dehumidifying the air flow 28.
The specification can be readily understood with reference to the following Representative Paragraphs:
Representative Paragraph 1. An air filtering process for a heating, ventilation, and air conditioning system (HVAC system) (1), in a motor vehicle (2), in which
Representative Paragraph 2. The air filtering process according to Representative Paragraph 1, characterized in that
Representative Paragraph 3. The air filtering process according to Representative Paragraph 2, characterized in that
Representative Paragraph 4. The air filtering process according to Representative Paragraph 3, characterized in that
Representative Paragraph 5. The air filtering process according to any of the Representative Paragraphs 1 to 4, characterized in that
Representative Paragraph 6. A heating, ventilation, and air conditioning system (HVAC system) (1) for a motor vehicle (2), which has
Representative Paragraph 7. The HVAC system (1) according to Representative Paragraph 6, characterized in that
Representative Paragraph 8. The HVAC system (1) according to Representative Paragraph 6 or 7, characterized in that
Representative Paragraph 9. The HVAC system (1) according to any of the Representative Paragraphs 6 to 8, characterized in that
Representative Paragraph 10. The HVAC system (1) according to any of the Representative Paragraphs 6 to 9, characterized in that
Representative Paragraph 11. The HVAC system (1) according to any of the Representative Paragraphs 6 to 10, characterized in that
Representative Paragraph 12. The HVAC system (1) according to any of the Representative Paragraphs 6 to 11, characterized in that
Representative Paragraph 13. The HVAC system (1) according to any of the Representative Paragraphs 6 to 12, characterized in that
Representative Paragraph 14. The HVAC system (1) according to any of the Representative Paragraphs 6 to 13, characterized in that
Representative Paragraph 15. The HVAC system (1) according to any of the Representative Paragraphs 6 to 14, characterized in that
Representative Paragraph 16. The HVAC system (1) according to any of the Representative Paragraphs 6 to 15, characterized in that
Representative Paragraph 17. The HVAC system (1) according to any of the Representative Paragraphs 6 to 16, characterized in that
| Number | Date | Country | Kind |
|---|---|---|---|
| 102023206819.2 | Jul 2023 | DE | national |
