WO2014206529A1

WO2014206529A1 - Defroster

Info

Publication number: WO2014206529A1
Application number: PCT/EP2014/001561
Authority: WO
Inventors: Andreas Maier
Original assignee: Daimler Ag
Priority date: 2013-06-25
Filing date: 2014-06-07
Publication date: 2014-12-31
Also published as: DE102013010622B3

Abstract

The invention relates to a defroster (10) for a pane of glass (11), in particular a windscreen, comprising a radiation source (12) for generating electromagnetic radiation (13) having a predetermined wavelength, selected such that the pane of glass (11) transmits the radiation (13) and comprises a coupling for coupling the radiation (13) into the pane of glass (11). Energy efficiency is improved if the defroster (10) also comprises a radiation detector (14) for measuring the intensity of the radiation (13) in the pane of glass (11) and the power of the radiation source (12) can be modulated with spatial resolution.

Description

de-icer

The present invention relates to a deicer for a glass pane, in particular a windshield, according to the preamble of claim 1. The invention also relates to an equipped with such a deicer glass pane, in particular a wind schutz schei be.

In order to enable the driver of a vehicle to see in the direction of travel and to protect him especially when driving against wind, weather and airborne particles floating in the air, vehicles are equipped in the prior art with a known windshield or windscreen glass. Such a windshield can be fixed in a float connected to the body of the vehicle windshield frame, on or glued or less often screwed and contributes with appropriate attachment and design to torsional stiffness of the body.

The problem here is the cleaning of generic windshields, which contributes to ensuring a clear view of the driver and thus ultimately to vehicle safety. While a veiling of the inside of the windshield can usually be averted by occasional wiping with a cloth, if necessary with the aid of glass cleaning agents, visual obstruction of the driver due to contamination of the windshield on the outside of a much greater challenge. This applies on the one hand for Residues in the form of dirt, dust, dead insects and bird droppings, which can accumulate while driving on the windshield, on the other hand also for ice deposits, which may form depending on the weather by the freezing of precipitates. While the former kind of soiling typically by means of washing water, sponges, rubber wipers or a built-in windscreen washer in the vehicle itself. eliminating ice causes the removal of ice while the use of an ice scraper at rest of the vehicle.

To remove ice deposits on the windshield when driving different heating devices are known in the art, which - usually by the direct or indirect supply of thermal energy - cause melting of the deposits, which enables the driver, the windshield by means of conventional windscreen wipers free from the now liquid water. In addition to an influx of the windshield with warm air come here, for example, electrical heating elements in the form of laid in a composite film fine wires or electrically conductive coatings of the windshield for use. However, depending on their specific design, these heating elements may themselves present a visual obstruction to the driver or adversely affect the action of the windshield as a design element of the vehicle. Further, conventional window heaters substantially heat the entire windshield uniformly and thus may contribute to increased energy consumption of the vehicle.

For these reasons, DE 10 2011 011 957 A1 proposes a method and a device for melting ice layers or other forms of frozen water adhering to the outside of vehicle windows made of mineral, plastic or laminated glass using technical means emitting heat rays in the vehicle interior. In this case, at least one heat radiator in the vehicle interior is mounted so that the heat rays impinge on the inside of the vehicle window with the dullest possible angle, the transmission through the mineral, plastic or laminated glass by at least the coupling of the heat rays on the inside of improving anti-reflection coating the vehicle window and by adapted thereto the choice of the wavelength of the heat rays is increased. For this purpose, the proposed device comprises a control unit which enables the driver to activate a time-limited pulse or continuous radiation of high radiation power by actuating an actuating unit.

DE 10 2008 060 015 A1 also deals with the described problem and discloses, in particular, a heatable windshield having at least one infrared radiator arranged in or on the pane for heating the pane, which is arranged in the pane or coupled to the pane, that the most of the infrared radiation emitted by it is totally reflected at interfaces of the disc.

DE 197 01 258 A1 is concerned with a rain sensor in which a light emitter and a light receiver are positioned on the vehicle window, wherein the signal measured at the light receiver is used for the detection of rain.

Finally, DE 10 2011 079 191 A1 also shows a potential solution in the form of a heating device, according to which the windshield represents a TIR light guide for infrared light and the heating device has at least one infrared light source which is set up and arranged for infrared light emitted by it to couple into the disk.

A disadvantage of these known approaches, however, lies in their low energy efficiency in view of the fact that an automatic shutdown of the respectively provided device usually does not take place. In this way, the driver is dependent on his own assessment of the progress of the de-icing process or a suitable timing, which can nevertheless assume only a preset time interval without knowledge of exact weather conditions or the degree of ice formation.

The present invention therefore addresses the problem of providing improved embodiments for a deicer and for a windscreen, which are characterized in particular by high energy efficiency.

According to the invention, this problem is solved by the subject matter of the independent claim. Advantageous embodiments are the subject of the dependent claims.

The invention is based on the general idea to equip the deicer not only with a radiation source and coupling for coupling electromagnetic radiation in the windshield, but to expand the generic arrangement by a suitable radiation detector. The radiation intensity determined by this radiation detector in the windshield, which serves as a transmission or propagation medium for the radiation, now allows a conclusion as to whether the windshield has ice deposits, in particular on its outer surface, resulting in a partial decoupling of radiation from the windshield itself lead, or if the radiation propagates in a state of total reflection only within the windshield, which can thus be seen as largely free of ice deposits.

The coupling may be arranged for this purpose in a relative orientation to the windshield, which ensures a substantial total reflection of the radiation at the phase interfaces, ie the inner and outer surfaces of the windshield, provided that the windshield is not frosted, but directly from outside air is flowed around. This orientation makes it possible to ensure that radiation exits the windshield only when it has deposited on it a foreign substance which has a refractive index which is comparable to that of the windshield material and differs from that of the air. Radiation energy is thus essentially derived from the windshield only if it actually has ice deposits. Overall, the embodiment described therefore helps the de-icer according to the invention to significantly improved energy efficiency compared to conventional devices.

Furthermore, a control device is provided which can in particular turn the radiation source on and off. In this case, it is advisable to configure the control device in such a way that it deactivates the radiation source and thus also terminates the coupling of electromagnetic waves into the windshield, as soon as the control device connected to the radiation detector for this purpose detects the exceeding of a specific limit value. This measure also contributes to the energy efficiency of the overall arrangement insofar as the achievement of the suitably chosen limit value is indicative of a substantial total reflection at the windshield interface, which makes the adhesion of appreciable ice deposits unlikely. In this case, the timely shutdown of the radiation source can prevent unnecessary energy losses that would otherwise be caused by the power consumption of the radiation source in its operating state.

If the radiation source is composed of a plurality of individually controllable segments which are monitored in their effect separately from correspondingly positioned radiation detectors, the radiation power of individual segments can be throttled when a specified transmission value is reached by the activating control device. Thus, both locally and temporally optimized heating of the windshield is possible. Multiple radiation sources can be monitored by a radiation detector when the radiation detector is operating sufficiently fast and the Radiation sources are operated with different modulated frequency. By means of Fourier transformation or lock-in amplifier can then be concluded that the transmission of the respective radiation source.

To enable the driver and any other vehicle occupants to turn on the deicer, in particular from the interior of the vehicle, the control unit can be provided with a suitable switch, which allows the switching of the radiation source, if necessary.

The functionality of the deicer can be extended by an uncomplicated structural modification to those of a rain detector when the radiation detector is extended by a - out in the controlled embodiment of the deicer optionally via the control unit - signal output for indicating precipitation. In this scenario, a low intensity of the measured radiation indicates an existing wetting of the windshield by precipitation, which due to its refractive index causes a leakage of radiation through the thus-wetted outer surface of the windshield. Such an expansion of function therefore makes a separate rain sensor dispensable and thus allows constructive simplifications and reduced manufacturing costs of a vehicle equipped according to the invention.

Preferably, the wavelength or frequency of the radiation is chosen so that their absorption is ensured by ice or water in the event of escaping from the windshield. On the basis of the temperature and other parameters of the degree of absorption realistic assumptions have to be made in this determination of the wavelength. The radiation that passes from the windshield into the respective absorber develops therein a thermal effect in the form of heating, which can promote the melting of ice deposits and the evaporation or evaporation of water molecules.

Radiation source and coupling may indeed be carried out separately according to an embodiment of the invention and connected by means of a suitable waveguide, such as a light guide. For the purpose of constructive simplification, however, an integral design of both components is recommended, so that the radiation source for coupling the radiation into the windshield is to be arranged in its immediate vicinity. Thus, at the same time energy losses are avoided on the line path, which again benefits the energy efficiency of the deicer. Other important features and advantages of the invention will become apparent from the dependent claims, from the drawings and from the associated figure description with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components.

Show, in each case schematically,

Figure 1 is a greatly simplified, principle view of a deicer according to the invention in its use for de-icing a windshield and

2 shows a windshield according to the invention.

FIG. 1 illustrates the use of a deicer 10 according to the invention for deicing a glass pane 11. By this term, any flat glass product comprising at least one amorphous, substantially translucent solid is to be understood in a broad sense, irrespective of the production method used. Arrangements known as laminated glass panes of a plurality of glass layers, which are connected by an adhesive-capable intermediate layer, for example made of plastic, are expressly included. However, the light transmittance feature does not exclude the partial application of colored sunscreen strips or a full-area tinting film on the glass sheet 1.

In the present case, the glass pane 11 has the shape of a windshield for installation in a passenger car and consists of a material called laminated safety glass (VSG) laminate of two glass layers, which by means of a tear-resistant and visco-elastic film, for example based on polyvinyl butyral (PVB) or ethylene vinyl acetate ( EVA) are glued together. The glass pane 11 may be provided in its function as a windshield with additional equipment features, such as an antenna, dirt or water-repellent coating and a known as a head-up display (HUD) device for the projection of driving information such as speed, navigation instructions or indicators on the glass 11. The material used to make the glass has a refractive index or refractive index of known optical property, assuming a wavelength of 589 nm approximately in a range of 1, 31 to 1, 33 and thus roughly between the refractive indices of frozen and liquid water.

For generating electromagnetic radiation, the glass pane 11 is in particular equipped with a radiation source 12, which emits a wave of coupled electric and magnetic fields, which can propagate largely unhindered in the material of the glass pane 11. In the present case, the radiation source 12 is configured to emit radiation 13 of a wavelength between 780 nm and 1 mm, which corresponds to a frequency range of 300 GHz to 400 THz. Electromagnetic radiation in said spectral range is familiar to the person skilled in the art as infrared radiation (IR radiation) and less generally known to the public as heat radiation, thermal radiation or temperature radiation. The radiation source 12 thus has in the given embodiment, the shape of an infrared radiator, which is connected for the purpose of energy supply to an electrical system of the passenger car. The radiation 13 emitted by the radiation source 12 preferably comprises a high proportion of so-called far infrared (FIR) of a wavelength of at least 50 μm, which is absorbed to a particularly high degree by ice and at the same time has a rather low penetration depth in this medium.

The radiation source 12, which at the same time fills the function of an optical coupling in the present scenario, is aligned with the glass pane 11 at an angle α, which guarantees a substantial total reflection (TIR) of the radiation 3 on the outer surface of the glass pane 1 1 in its dry state , When impinging on the phase interface 15 between the glass pane 1 1 and the surrounding air flowing around the angle of incidence of the radiation 13 should not fall below an angle of incidence, below which only a comparatively small proportion of the radiation 13 in the amount of, for example, 5% of the phase interface 15 in the interior of the glass pane 1 1 can be reflected. The described angle is referred to in optics and electrodynamics as critical angle of total reflection or critical angle.

An essential element of the deicer 10 now lies in a radiation detector 14 comprised by the latter, which is suitable for detecting IR radiation due to its construction. is net. In the present case, this is a radiation sensor known to the physicist as a bolometer or boulometric sensor, whose operating principle is based on a heating brought about by absorption of the radiation 13, which in turn can be detected, for example, by using a thermistor. In an alternative embodiment of the deicer according to the invention, the radiation detector 14 may be in the form of a simple thermocouple, which converts heat into electrical energy by means of thermoelectricity, in particular the so-called Seebeck effect.

To control the radiation source 12, the deicer 10 further comprises a control unit (ECU, ECM) 16, which may be connected to the former, for example, by means of a fieldbus known from vehicle electronics, for example a controller area network (CAN bus). A suitable switch (not shown) which in turn is connected to the control unit 16 allows the driver to switch on the radiation source 12 if necessary. In addition, the control unit 16 is connected to the radiation detector 14, which in this arrangement serves primarily to detect the emission of radiation 13 from the glass pane 11 in the form of a reduced radiation intensity. The weakening of the radiation 13 caused here by the ice deposit 17 is interpreted by the control unit 16 as an indication of at least partial icing of the glass pane 11. As long as the intensity of the radiation 13 measured by the radiation detector 14 permits such a conclusion, the control unit 16 leaves the radiation source 12 in its active operating state. However, as soon as the said intensity reaches a predetermined threshold value, which according to the configuration of the control device 16 indicates a TIR of the radiation transmitted through the glass pane 11, the control device 16 switches off the radiation source 12 automatically and thus terminates the coupling of further radiant energy into the glass pane 11.

FIG. 2 now shows another glass pane 21 designed in the form of a windshield. This design variant is characterized by a large number of de-icers according to the invention, as already described in connection with FIG. As can now be seen from FIG. 2, in this case the radiation sources 22, which already comprise a coupling as in the case of the deicer 10, and radiation detectors 24 of the deicer are arranged in alternating sequence along two opposite side edges of the glass pane 21. For each individual deicer, the radiation detector 24 associated with its radiation source 22 and coupling is thus located on the other side of the glass pane 21. An ice deposit 27 on the glass pane 21 can be located in this way effectively melt, with the parallel arrangement and number of deicer also allows a precise localization of the defect.

Claims

claims

1. deicer (10) for a glass pane (11, 21), in particular a windshield,

- With a radiation source (12, 22) for generating an electromagnetic radiation (13, 23) of a predetermined wavelength, selected such that the glass pane (11, 21), the radiation (13, 23) transmits, and

- With a coupling for coupling the radiation (13, 23) in the glass sheet (11, 21), characterized by

a radiation detector (14, 24) for determining the amount of radiation absorbed between radiation source (12, 22) and radiation detector (14, 24), wherein a control device (16) connected to the radiation detector (14, 24) for controlling the radiation source (12, 22), configured such that the control device (16) switches off the radiation source (12, 22) when the measured intensity of the radiation (13, 23) exceeds a predetermined maximum value.

2. deicer (10) according to claim 1,

characterized in that both the coupling of the radiation and the detection of the absorbed radiation quantity spatially resolved, so over several individually controllable segments of the radiation source, which are monitored separately from correspondingly positioned radiation detectors along at least two opposite sides of the glass sheet (11, 21 ) is measured and / or influenced.

3. deicer (10) according to claim 1 or 2,

characterized in that

the coupling is aligned with the glass pane (11, 21) in such a way that it couples the radiation (13, 23) into the glass pane (11, 21) at an angle (a) chosen such that a phase boundary surface (15, 25 ) substantially completely reflects the radiation (13, 23) between the glass pane (11, 21) and outside air.

4. Deicer (10) according to one of claims 1 to 3,

characterized in that

the controller (16) has a switch and is configured such that the controller (16) turns on the radiation source (12, 22) when the switch is actuated.

5. deicer (10) according to any one of claims 1 to 4,

characterized in that

the radiation detector (14, 24) has a signal output for signaling precipitation and is configured such that the signal output signals the precipitation when the intensity of the radiation (13, 23) falls below a predetermined minimum value.

6. deicer (10) according to any one of claims 1 to 5,

characterized in that

the wavelength is further selected such that ice (17, 27) and / or water can absorb the radiation (13, 23).

7. deicer (10) according to any one of claims 1 to 6,

characterized in that

the radiation source (12, 22) and the coupling are formed integrally.

8. glass pane (11, 21), in particular windscreen, with a deicer (10) according to one of claims 1 to 7, wherein the glass pane (11, 21) has a refractive index at the predetermined wavelength and predetermined angle of incidence of the IR radiation no total reflection at a phase interface to material with a refractive index of ice (17, 27) possible.

9. glass pane (11, 21) according to claim 8,

marked by

A plurality of deicers (10) according to any one of claims 1 to 7, wherein for each deicer (10) the radiation source (12, 22) is attached to a first side edge of the glass sheet (11, 12).

21) and the radiation detector (12, 22) are arranged on a second side edge of the glass pane (11, 21) opposite the first side edge such that along the first side edge and the second side edge the radiation sources (12,

22) and the radiation detectors (14, 24) substantially alternate.