DE102011078853A1 - Generation of an air flow by means of vibrations - Google Patents

Abstract

The invention relates to a turbomachine (H) having an air flow generating unit (1) which can be excited to oscillate, the air flow generating unit (1) having a Chladni resonator (3, 9) with at least one resonantly activatable plate (3). A lighting device (R) has at least one turbomachine (H) for cooling at least one light source (L). The method is used to generate a cooling air flow (K), wherein the method comprises exciting a plate (3) of a Chladni resonator (3, 9). The invention is particularly advantageously applicable for cooling of LED lamps and / or lamps that can be equipped with them.

Description

The invention relates to a turbomachine with a vibratory stimulable air flow generating unit, wherein the air flow generating unit comprises a Chladni resonator with at least one resonant excitable plate. The invention further relates to a lighting device, comprising at least one such turbomachine for cooling at least one light source. The invention also relates to a method for generating an air flow, in particular cooling air flow, by exciting an air flow generating unit to oscillate. The invention is particularly advantageously applicable for cooling of LED lamps and / or lamps that can be equipped with them.

DE 10 2008 038 549 A1 discloses a method for generating an air flow by means of ultrasound, for the cooling of small electronic circuits, such as electronic ballasts. For this purpose, a device for generating an air flow with an excitation element and a vibrating element is described, wherein the vibrating element can be excited to oscillate by the excitation element and the oscillations lead to an air flow. In particular, a connecting element between the excitation element and the vibrating element may be provided and mechanically connected to both. The connecting element may be formed frusto-conical and be completed at its lid and bottom surface of the vibrating element and the excitation element. Specifically, it is proposed to excite and operate a piezoelectric actuator with a vibrating diaphragm mounted in front of it with ultrasonic frequencies. The vibrations of the vibrating diaphragm create an air flow which cools the circuit.

Furthermore, natural vibrations of plates are known. In this case, fixed positions for resonant oscillation maxima and oscillation minima are formed on the plate for fixed boundary conditions. can be made visible by sprinkling the plate with sand (creation of Chladnic sound figures). A resonant or self-resonant plate may also be referred to as a Chladni resonator.

It is the object of the present invention to provide a particularly simple and compact way of generating an air flow by means of mechanical vibrations.

This object is achieved according to the features of the independent claims. Preferred embodiments are in particular the dependent claims.

The object is achieved by a turbomachine with an airflow generating unit which can be excited to oscillate, wherein the airflow generating unit has a Chladni resonator with at least one resonantly excitable plate.

In particular, a turbomachine can be understood to mean a gas energy machine in which energy is transferred between gas (in particular air) and machine in an open space through a flow in accordance with the laws of fluid dynamics via the kinetic energy.

This turbomachine has the advantage that its air flow generating unit is particularly flat ausgestaltbar. Also, the air flow generating unit may be configured over a large area without special efforts. In addition, this turbomachine can be easily and inexpensively manufactured. The turbomachine may be in addition to the at least one air flow generating unit, e.g. Also electrical connections, a holder, air guiding devices and / or a driver for electrical operation of the air flow generating unit, etc. have.

Of course, the turbomachine can bring or promote another gaseous medium than air to the flow. Thus, the description of this invention is not limited to "air," and a reference to air may include, in particular, any gaseous medium.

It is a preferred embodiment for enabling a particularly compact and precisely excitable turbomachine that the plate can be excited by means of at least one volumetric actuator. In particular, a volumetric actuator can be understood as any actuator which can change its material volume in a defined manner by means of an external control signal (for example a voltage, a magnetic field). For example, a volumetric actuator may include an electrostrictive actuator or a magnetostrictive actuator. Due to its robustness, compact design, its comparatively inexpensive production and its simple activation, however, a piezoelectric actuator or piezoelectric actuator is particularly preferred. The actuator can in particular be glued to the plate.

It is still an embodiment that the plate can be excited by means of a matrix-like array of actuators. Thus, particularly uniform or deliberately uneven vibration amplitudes can be achieved across the plate. In particular, the actors like individually or in groups be controllable to produce a predetermined resonance pattern.

Alternatively, however, the plate may also be e.g. be stimulated by a, in particular central, actuator to natural oscillations or to resonance.

It is yet a further embodiment that the at least one volumetric actuator is configured as a piezoactuator plate. Thus, a particularly flat and inexpensive air flow generating unit can be provided.

It is also an embodiment that the plate with a frequency of at least about 50 kHz, in particular of at least about 100 kHz, in particular of at least about 200 kHz, can be excited. Thus, a strong air flow can be produced at an (ultrasonic) frequency that is no longer audible for humans and most animals.

It is also an embodiment that the plate is a metal plate. A metal plate is particularly easy excitable to natural vibrations with high amplitudes, inexpensive available and simply variable in their properties.

It is still an embodiment that the plate is a plastic plate, which can be particularly light, durable and inexpensive. It is a development that the plastic plate is connected to a piezoelectric plastic film. The piezoelectric plastic film serves as an actuator or actuator field and may in particular be connected to the plastic plate as a large-area layer composite. This enables a particularly flat and robust air flow generating unit. The piezoelectric plastic film may consist in particular of polyvinylidene fluoride (abbreviation PVDF).

It is still an embodiment that the plate is a ceramic plate. The ceramic used may in particular be a ceramic with a low acoustic attenuation. If the at least one actuator, in particular piezoelectric actuator, is a ceramic actuator, the at least one actuator can be sintered to the plate to form a piece.

It is also an embodiment that the plate is suspended vibrating on webs. Thus, a simple suspension and alignment of the plate can be achieved without a substantial restriction of its ability to vibrate. The webs can hold or fasten the plate to a frame. In particular, the frame and the plate may be formed from a full-surface layer or (semi-finished or starting) plate, in particular by incorporation of corresponding recesses, e.g. by means of a mechanical material removal or by means of a laser ablation, in particular a laser cutting. In particular, in this embodiment, but also quite generally, the air flow generating unit may have a plurality of resonant excitable plates.

It is an advantageous for a little disturbing suspension configuration that the plate is a polygonal plate at the corners attach the webs. However, the plate may be e.g. also be a round or oval plate, etc., in which case the webs can then in particular be equidistant.

It is yet another embodiment that at least one region of the plate, which forms a maximum vibration, a Übertragerelement is present, which mechanically connects this area with a vibration unit, so that the vibration unit can be excited from this area to vibrations. So the transformer element may vibrate particularly strong, thus causing a particularly strong vibration of the vibration unit and thus a particularly strong flow of cooling air.

It is yet another embodiment that at least one region of the plate, which is located between a maximum vibration and a minimum vibration, a transformer element is present, which mechanically connects this area with a vibration unit, so that the vibration unit can be excited from this area to vibrations , Thus, the air flow generating unit can be adapted to a high quality factor, which can also cause a particularly strong vibration of the vibration unit and thus a particularly strong flow of cooling air.

It is yet a further embodiment that a transformer element is present on at least one region of the plate on which there is also a vibration minimum, which mechanically connects this region with a vibration unit, so that the vibration unit can be excited to oscillate from this region. Thus, the air flow generating unit can also be adapted to a high quality factor.

The positions of the vibration minima and vibration maxima forming on the plate during operation need not coincide with a position of the at least one actuator. It is a preferred development for a particularly durable connection between the at least one actuator, in particular adhered actuator, and the plate, that the actuator is arranged in the region of a vibration minimum.

It is a development that the Übertragerelement has a cone-like basic shape, which tapers from the plate to the vibration unit. Thereby, a vibration amplitude can be amplified at the vibration unit.

The oscillation unit protrudes laterally beyond its contact surface with the transmitter element for particularly effective generation of an air flow.

It is a development which is particularly preferred for a simple and inexpensive production of the transformer element that at least the transformer element has a plurality of layers or is composed of such layers (ie is a layered body). An advantage consists in the production of at least the transformer element by simple layering, in particular by means of pre-structured layers or plates, instead of a complex machining of a solid material. Among other things, the transformer element makes use of the fact that an outer contour that is favorable for the function does not necessarily have to be smooth, since in the case of typical, sufficiently large wavelengths generated by the plate of the Chladni resonator, the excitation over the structure present in this structure Remove steps.

It is a preferred embodiment for a simple and compact production that the transformer element and the vibration unit are present as a common layer body, ie the vibration unit is also constructed from one or more layers.

It is also an embodiment that the plate has recesses serving as air channels. This improves a uniform air supply across the plate, which in turn enables more uniform airflows across the surface of the plate.

The object is also achieved by a lighting device, comprising at least one turbomachine for cooling at least one light source, wherein the at least one turbomachine is a turbomachine as described above.

The lighting device may be a lamp, a module, a light or a lighting system. For example, the lighting device may be a luminaire, e.g. a ceiling light, which has a reflector. The reflector (or a reflector of another lighting device) can serve as the plate of the Chladni resonator and thus assume both a reflection function and a cooling function.

The light source may in particular be a semiconductor light source. Preferably, the at least one semiconductor light source comprises at least one light-emitting diode. If several LEDs are present, they can be lit in the same color or in different colors. A color may be monochrome (e.g., red, green, blue, etc.) or multichrome (e.g., white). The light emitted by the at least one light-emitting diode can also be an infrared light (IR LED) or an ultraviolet light (UV LED). Several light emitting diodes can produce a mixed light; e.g. a white mixed light. The at least one light-emitting diode may contain at least one wavelength-converting phosphor (conversion LED). The phosphor may alternatively or additionally be arranged remotely from the light-emitting diode ("remote phosphor"). The at least one light-emitting diode can be in the form of at least one individually housed light-emitting diode or in the form of at least one LED chip. Several LED chips can be mounted on a common substrate ("submount"). The at least one light emitting diode may be equipped with at least one own and / or common optics for beam guidance, e.g. at least one Fresnel lens, collimator, and so on. Instead of or in addition to inorganic light emitting diodes, e.g. based on InGaN or AlInGaP, organic LEDs (OLEDs, for example polymer OLEDs) can generally also be used. Alternatively, the at least one semiconductor light source may be e.g. have at least one diode laser.

The object is further achieved by a method for generating a cooling air flow, the method comprising exciting a plate of a Chladni resonator. This method allows the same advantages as the lighting device and can be configured in an analogous manner.

For example, it may be an embodiment that a movement of the excited plate of the Chladni resonator is transmitted by means of a Übertragerelements on a vibration unit, wherein the moving vibration unit generates the cooling air flow.

The above-described characteristics, features, and advantages of this invention, as well as the manner in which they will be achieved, will become clearer and more clearly understood in connection with the following schematic description of exemplary embodiments which will be described in detail in conjunction with the drawings. In this case, the same or equivalent elements may be provided with the same reference numerals for clarity.

1 shows in an oblique view from above an exploded view of an air flow generating unit according to a first embodiment;

2 shows a sectional side view of a section of the air flow generating unit in the region of a transformer element;

3 shows a Chladni plate of the air flow generating unit in plan view;

4 shows in plan view a section of an air flow generating unit according to a second embodiment;

5 shows a lighting device with an air flow generating unit according to the first or the second embodiment.

1 shows in an oblique view from above an exploded view of an air flow generating unit 1 according to a first embodiment. The air flow generation unit 1 is made up of several layered plates 3 to 7 built up.

A bottom in this view, metallic plate 3 ("Chladni plate") is a full-surface plate. The Chladni plate 3 has on its underside thirty-five circular disk-shaped (plate-shaped) piezoelectric actuators 9 on, for example, to the Chladni plate 3 can be glued. The Chladni plate 3 and the piezo actuators 9 form a Chladni resonator 3 . 9 , where the piezo actuators 9 the Chladni plate 3 can stimulate natural oscillations.

The piezo actuators 9 are here arranged in an m × n matrix pattern with, for example, m equal to seven and n equal to five. The piezo actuators 9 can be activated via electrical signals, with no electrodes, electrical insulation, electrical connections, etc. are shown here for clarity, even if they can be present.

On the Chladni plate 3 are four more plates 4 to 7 stacked up. Each of the plates 4 to 7 is structured such that several partially separated, circular sections 4a to 7a available. The subareas 4a to 7a are analogous to the piezo actuators 9 arranged in a congruent 7 × 5 matrix pattern. The subareas 4a to 7a are especially in the same pattern on the plates 4 to 7 arranged that superimposed subareas 4a to 7a and a piezoelectric actuator arranged thereunder 9 are arranged concentrically with each other.

The subareas 4a to 7a are with a remaining layer frame 4b to 7b over each here three bars 8th integrally connected. Through the bars 8th become the subareas 4a to 7a capable of oscillating in the respective layer frame 4b to 7b held. The vibration characteristics of the subregions 4a to 7a are then also by the properties of the webs 8th , eg their number, dimensions and / or material. For example, the number of bars 8th per section 4a to 7a be chosen variable, for example, in relation to a desired strength.

The partial separation of the subareas 4a to 7a For example, by introducing three ring-sector-shaped recesses 11 per section 4a to 7a in a full-surface plate 4 to 7 be performed. The partial separation can be carried out, for example, by means of an etching process, a stamping process or a laser structuring, in particular laser cutting, process from the full-surface plate 4 to 7 be achieved. Alternatively, at least one of the plates may 4 to 7 already in the partially separated sections 4a to 7a having been produced.

The subareas 4a . 5a . 6a the first three plates ("transformer plates") 4 to 6 above the Chladni plate 3 each form a transformer element 4a . 5a . 6a , The subareas 4a . 5a . 6a Although they have the same circular basic shape, but with increasing distance from the Chladni plate 3 in their area (here: in their diameter) smaller. The shape of the transformer element 4a . 5a . 6a is thus a truncated cone.

The subareas 7a the top plate 7 ("Vibration plate") have a larger diameter than the sections 6a the directly below connecting plate 6 , The subareas 7a form a respective vibration unit.

The plates 3 to 7 , especially 4 to 7 , may be made of the same material, or the connecting plates 4 to 6 can consist of a same material and the vibration plate 7 can consist of a different material. The plates 4 to 7 can be made of metal, plastic and / or ceramic.

For the production of the air flow generating unit 1 become the plates 3 to 7 connected to a fixed layer stack. This bonding can be achieved for example by gluing, for example by means of epoxy resin. Metallic plates 3 to 7 can also be soldered together, ceramic plates 3 to 7 be sintered with each other.

2 shows a section in side view of a section of the air flow generating unit 1 in the area of a transformer element 4a to 6a ,

In operation, by applying an electrical signal, in particular an alternating voltage, to the piezoelectric element 9 this to mechanical vibrations (in particular acoustic Vibrations, in particular ultrasonic vibrations of at least 100 kHz) excited. The vibrations are on the Chladni plate 3 transmitted, which is thereby excited to natural oscillations. The natural vibrations of the Chladni plate 3 continue on the transformer element 4a . 5a . 6a transferred, and from there on to the vibration unit 7a , The transformer element 4a . 5a . 6a due to its tapered shape, amplifies a vibration amplitude at the sub-region or the vibration unit 7a , The vibration unit 7a in turn, generates a desired airflow.

In particular, the material and / or the thickness of the subregions 4a to 6a and / or subsection 7a can be due to a low vibration damping and / or to a strong excitation of the subarea 7a be designed towards.

That the outer contour of the Übertragerelements 4a . 5a . 6a is formed stage, is not a disadvantage, because the thickness is typically small compared to a wavelength of one of the Chladni plate 3 generated natural vibration and thus is not resolved by the mechanical shaft.

3 shows the Chladni plate 3 the air flow generating unit 1 in plan view. The Chladni plate 3 has a rectangular shape and is at its corners via webs 12 with a frame 13 connected. By means of the bridges 12 remains the edge of the Chladni plate 3 capable of vibrating. The through the piezo actuators 9 covered areas 14 the Chladni plate 3 are shown in dashed lines

In the air flow generation unit 1 containing several transformer elements 4a . 5a . 6a and vibration units 7a in a frame 4b to 7b it can, with a large lateral extent with many Übertragerelementen 4a . 5a . 6a and vibration units 7a happen, that an air supply to the vibration units 7a is not uniform, because at the edge of the air flow generating unit 1 located vibration units 7a be supplied with air better than internally arranged vibration units 7a , As a result, however, an efficiency of the air flow generation and consequently a cooling capacity from outside to inside may decrease.

To supply air or air to the vibration units 7a to improve, in particular to even, can, as with the air flow generation unit 15 in 4 shown to the side of the piezoelectric actuators 9 occupied areas 14 the Chladni plate 3 air ducts 16 in the air flow generation unit 15 to be available. The air channels run through the stacked layer frames 4b to 7b therethrough. This allows air from a back of the air flow generating unit 15 to its front, which the vibration units 7a has, be sucked or tracked.

A contour of the air ducts 16 can, as in 4 shown, for a good space utilization essentially the shape of the adjacent areas 14 the Chladni plate 3 correspond. Alternatively, the contour of the air ducts may be oriented in particular to simple geometric shapes, for example a circular shape, in order to simplify manufacture.

The air flow generation unit 15 Otherwise, it may be particularly like the air flow generating unit 1 be educated.

5 shows a lighting device R with a turbomachine H, which is an air flow generating unit 1 or 15 having. The lighting device R further comprises two semiconductor light sources, in particular LEDs, L, which by means of one of the air flow generating unit 1 or 15 generated cooling air flow K are cooled.

An air flow generation unit 1 having turbomachine H, in addition to the air flow generating unit 1 For example, electrical connections, air guiding devices, a holder and / or a driver for electrical operation of the piezoelectric actuators 9 etc. (not illustrated).

Although the invention has been further illustrated and described in detail by the illustrated embodiments, the invention is not so limited and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

So like the transformer elements 4a . 5a . 6a and the vibration units 7a also laterally offset to the piezo actuators 9 be arranged.

In particular, like the transformer elements 4a . 5a . 6a on areas of the Chladni plate 3 which are not also (from the other side) of piezo actuators 9 are covered. Thus, a particularly high oscillation amplitude of the Chladni plate 3 be exploited if the areas 14 Low vibration amplitude (including a vibration minimum) correspond. In the embodiments shown, for example, transformer elements arranged in a 6 × 4 matrix field may be used for this purpose 4a . 5a . 6a between the vacancies present in the 7 × 5 matrix field.

However, the transformer elements like 4a . 5a . 6a with those of piezo actuators 9 covered areas 14 overlap or even rest on it as shown above. The areas 14 like though have a comparatively low oscillation amplitude, but lying on it Übertragerelemente 4a . 5a . 6a may cause a particularly high quality factor.

In general, the transformer elements 4a . 5a . 6a and the vibration units 7a on areas of the Chladni plate 3 be arranged, which correspond to areas with oscillation maxima, areas with vibration minima or areas between them.

LIST OF REFERENCE NUMBERS

1

 Air flow generating unit

3

 Chladni Plate

4

 plate

4a

 subregion

4b

 layer frame

5

 plate

5a

 subregion

5b

 layer frame

6

 plate

6a

 subregion

6b

 layer frame

7

 plate

7a

 subregion

7b

 layer frame

8th

 web

9

 piezo actuator

11

 recess

12

 web

13

 frame

14

 covered area

15

 Air flow generating unit

16

 air duct

R

 lighting device

H

 flow machine

L

 LED

K

 Cooling air flow

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 102008038549 A1 [0002]

Claims (15)

Turbomachine (H) with a vibratory excitable air flow generating unit ( 1 ; 15 ), wherein the air flow generation unit ( 1 ; 15 ) a Chladni resonator ( 3 . 9 ) with at least one resonant excitable plate ( 3 ) having. Turbomachine (H) according to claim 1, wherein the plate ( 3 ) by means of at least one volumetric actuator, in particular piezoelectric actuator ( 9 ), is excitable. Turbomachine (H) according to claim 2, wherein the plate ( 3 ) by means of a matrix-like arranged group of actuators ( 9 ) is excitable. Turbomachine (H) according to one of claims 2 or 3, wherein the at least one volumetric actuator as a Piezoaktorisches platelets ( 9 ) is configured. Turbomachine (H) according to one of the preceding claims, wherein the plate ( 3 ) with a frequency of at least about 50 kHz, in particular of at least about 100 kHz, in particular of at least about 200 kHz, can be excited. Turbomachine (H) according to one of the preceding claims, wherein the plate ( 3 ) is a metal plate. Turbomachine (H) according to one of claims 1 to 5, wherein the plate ( 3 ) is a plastic plate, which is connected to a piezoelectric plastic film, in particular of polyvinylidene fluoride. Turbomachine (H) according to one of the preceding claims, wherein the plate ( 3 ) capable of vibrating on webs ( 12 ) is suspended. Turbomachine (H) according to claim 8, wherein the plate ( 3 ) is a polygonal plate, at the corners of the webs ( 12 ). Turbomachine (H) according to one of the preceding claims, wherein on at least a portion of the plate ( 3 ), which forms a maximum vibration, a transformer element ( 4a . 5a . 6a ), which surrounds this area with a vibration unit ( 7a ) mechanically connects, so that the vibration unit ( 7a ) is excitable from this area to vibrations. Turbomachine (H) according to one of the preceding claims, wherein on at least a portion of the plate ( 3 ), which is located between a maximum vibration and a minimum vibration, a transformer element ( 4a . 5a . 6a ), which surrounds this area with a vibration unit ( 7a ) mechanically connects, so that the vibration unit ( 7a ) is excitable from this area to vibrations. Turbomachine (H) according to one of claims 10 or 11, wherein the plate ( 3 ) serving as air channels recesses ( 11 ) having. Lighting device (R), comprising at least one turbomachine (H) for cooling at least one light source (L), wherein the at least one turbomachine (H) is a turbomachine (H) according to one of the preceding claims. A method of generating a cooling air flow, the method comprising exciting a plate ( 3 ) of a Chladni resonator ( 3 . 9 ). A method according to claim 14, wherein movement of the stimulated plate ( 3 ) of the Chladni resonator ( 3 . 9 ) by means of a transformer element ( 4a . 5a . 6a ) on a vibration unit ( 7a ), wherein the moving vibration unit ( 7a ) generates the cooling air flow.

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