Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L23/00—Details of semiconductor or other solid state devices
  • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
  • H01L23/42—Fillings or auxiliary members in containers or encapsulations selected or arranged to facilitate heating or cooling
  • H01L23/433—Auxiliary members in containers characterised by their shape, e.g. pistons
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V29/00—Protecting lighting devices from thermal damage; Cooling or heating arrangements specially adapted for lighting devices or systems
  • F21V29/50—Cooling arrangements
  • F21V29/70—Cooling arrangements characterised by passive heat-dissipating elements, e.g. heat-sinks
  • F21V29/83—Cooling arrangements characterised by passive heat-dissipating elements, e.g. heat-sinks the elements having apertures, ducts or channels, e.g. heat radiation holes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L23/00—Details of semiconductor or other solid state devices
  • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
  • H01L23/42—Fillings or auxiliary members in containers or encapsulations selected or arranged to facilitate heating or cooling
  • H01L23/433—Auxiliary members in containers characterised by their shape, e.g. pistons
  • H01L23/4336—Auxiliary members in containers characterised by their shape, e.g. pistons in combination with jet impingement
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L23/00—Details of semiconductor or other solid state devices
  • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
  • H01L23/46—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements involving the transfer of heat by flowing fluids
  • H01L23/467—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements involving the transfer of heat by flowing fluids by flowing gases, e.g. air
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
  • H01L33/64—Heat extraction or cooling elements
  • H01L33/642—Heat extraction or cooling elements characterized by the shape
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
  • F21Y2115/00—Light-generating elements of semiconductor light sources
  • F21Y2115/10—Light-emitting diodes [LED]
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/0001—Technical content checked by a classifier
  • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Definitions

• the present invention relates to a cooling arrangement for cooling a heat generating electrical component.
• the present invention further relates to an electrical device comprising such a cooling device.
• active cooling arrangements for cooling heat generating electrical components, such as LEDs or ICs
• active cooling arrangements comprise fans, propellers or synthetic jets, that all enhance the heat transfer by forced convection.
• a synthetic jet is disclosed in US 6 123 145, wherein a diaphragm in the wall moves to simultaneously move the volume in a container with the result that vortices are ejected from the chamber through the orifice. The synthetic jet that is hence generated impinges on a heated surface to cool it.
• Conventional active cooling arrangements are commonly subjected to fouling and limited lifespan, they make audible noise, are costly, heavy and require extra space and power, which is an issue when it comes to for example lighting, which is particularly demanding regarding these issues.
• an object of the present invention is to provide an improved cooling arrangement.
• a cooling arrangement for cooling a heat generating electrical component comprising a heat spreading element that has a mounting surface adapted to be thermally connected to the heat generating electrical component, and a heat rejection surface; an enclosure arranged to cover the heat rejection surface and form an essentially closed compartment; an opening leading into the compartment; an annular member coaxially aligned with the opening; and an actuator connected to the annular member, and arranged to move the annular member reciprocating away from/toward the opening, so that the annular member generates a jet directed through the opening toward the outside of the enclosure.
• the jet causes forced heat convection from the heat rejection surface, thus enhancing the convective cooling of the heat spreading element.
• the arrangement enables zero net mass transfer, yet generating nonzero momentum transfer for forced convection in a narrow enclosure.
• An advantage with an outward jet is that it puffs out hot air while sucking in fresh air from elsewhere. Vortex shedding is generated by air displacement and occurs as the annular member moves reciprocating away from/toward the opening actuated by the actuator, with the cross section of the annular member in a plane normal to the direction of the motion.
• a “heat spreading device” is here a device that spreads the heat which is generated by a heat generating electrical component. Such a device may be a heat spreader and/or a heat sink, or a circuit board, such as a metal core printed circuit board, MCPCB.
• An “actuator” is here a device that is connected to the annular member and actuates the reciprocating movement of it.
• An active cooling device comprising an actuated tubular member is described in the non-published European Patent Application 07122623.7.
• this tubular member is adapted to primarily generate inward synthetic jets toward the object, and is further based on the realization that the object to be cooled is arranged inside an enclosure. Due to the enclosure such an arrangement is relatively big in size and accordingly requires a relatively big space when mounted. For example LEDs or ICs do not have an enclosure, and therefore put additional demands on a cooling arrangement.
• the present invention is based on the realization that the outward jet is generated even if the distance between the annular member and the heat spreader or enclosure wall is small.
• the outward jet(s) enhance convection.
• the surface of the annular member acts to pump the air, and since this surface may be relatively big compared to the orifice, the pumping action becomes more powerful.
• the opening may be arranged in the wall of the enclosure or alternatively in the heat spreading element, depending on the application.
• the enclosure may comprise at least one additional opening, to increase the inward flow into the enclosure, hence boosting the flow inside the enclosure and intensifying the cooling of the heat rejection surface.
• Each opening affects the air displacement and hence the cooling effect of the cooling arrangement.
• the actuator may be integrated in the enclosure, which makes the cooling arrangement more compact. In this case the opening may be formed in the actuator, which makes the arrangement even more compact.
• the actuator may preferably be a loudspeaker, which loudspeaker comprises a magnet, a coil and a membrane.
• the annular member may be connected to the coil of the loudspeaker, and the coil may be suspended and guided by the membrane. It is possible to tune the resonance frequency of a loudspeaker, just by adding moving mass to it. Hence, tuning of the resonance frequency of the loudspeaker is allowed by adjustment of the mass of the annular member.
• the additional mass of the annular member allows that the resonance frequency of the loudpeaker may be subsonic or low. Operation at a low frequency implies low audible noise as well as longer life time. Thus, sophisticated and expensive noise reduction is not required.
• loudspeakers Another advantage with loudspeakers is that vortex shedding (and synthetic jet formation) may be boosted by pumping of loudspeaker (cones) with modest excursion. Moreover, guidance of the annular member is integrated in a loudspeaker, which guidance is important to reduce play, and hence leakage.
• actuators include for examples a crank-connecting rod mechanism, a plunger or a membrane pump.
• the opening may be formed in the loudspeaker magnet, which make the arrangement compact, and no major construction modification of the loudspeaker is thus required.
• the cooling arrangement may comprise a tubular member that extends through the opening, which tubular member has a first open end arranged inside the enclosure connected to the annular member, and a second open end arranged outside the enclosure.
• the annular member may hence form a flange on the tubular member. Accordingly, tuning of the resonance frequency of the loudspeaker is allowed by adjustment of the mass of the annular and tubular member. Further, the moving air mass is approximately proportional to the length of the tubular member and the thickness of the flange. The surface of the flange of the tubular member and of the membrane pump the air, and since this surface is relatively big the pumping action becomes more powerful.
• the loudspeaker coil and the loudspeaker membrane may be arranged inside the compartment whereby the membrane divides the inside of the enclosure into two sub compartments, each provided with at least one opening. At least one of the openings leading from the first sub compartment may further be connected to at least one of the openings leading from the second sub compartment. This may be advantageous since the cooling arrangements becomes compact and more effective taking usage of the double action pump effects of the arrangement. Moreover, at least one of the openings leading from the first sub compartment may be connected to at least one of the openings leading from a second sub compartment via a ⁇ -pipe, where ⁇ is the wave length generated by the actuator.
• the pipe hence connects the backside of the loudspeaker membrane to the opposite side of the membrane. In case the loudspeaker backside must be closed, the pipe will act as the only additional opening.
• the distance between the annular member and an opposing surface may be adapted to allow a jet to develop toward the inside of the enclosure.
• Such an internal jet is advantageous for directing a jet toward the hot spot of the heat generating electrical component, such as a LED and/or the heat rejection surface of the heat spreader.
• the arrangement hence enables efficient cooling by synthetic jet impingement.
• the distance between the annular member and the opposing surface may be at least 2 times the opening diameter of the annular member to allow the inner jet to develop, but preferably at maximum 10 times the opening diameter.
• the cooling arrangement according to the present invention may, furthermore, advantageously be comprised in an electrical device including electrical components.
• Figure 1 is an exploded perspective view of a cooling arrangement according to an embodiment of the present invention.
• Figure 2 is a cross-section view of an exemplary cooling arrangement according to a further embodiment of the present invention.
• FIG. 1 a LED 1 is thermally connected to the mounting surface 3 side of the heat spreading element 2 to be cooled by so called forced convection.
• An enclosure 5 surrounds the arrangement on the heat rejection surface 4 side of the heat spreading element 2, thus forming an essentially enclosed compartment.
• An actuator here a loudspeaker, is arranged inside the enclosure 5, being integrated in the wall of the enclosure 5, which loudspeaker comprises a coil 6, a membrane 7 and a magnet 8.
• the loudspeaker is arranged opposite the heat rejection surface 4 side of the heat spreader 2.
• an opening 13 leads into the compartment and in the illustrated example it is formed in the magnet 8 of the loudspeaker.
• An annular member 11 is coaxially aligned with the opening 13, and connected to the actuator, here the loudspeaker coil 6.
• the loudspeaker coil 6 is further suspended by the loudspeaker membrane 7.
• the annular member 11 is moreover equipped with a tube 9, which is arranged to extend through the opening 13 in the loudspeaker magnet 8 and the enclosure 5.
• the first open end of the tube is arranged inside the enclosure 5 and the second open end is arranged outside the enclosure 5.
• the annular member 11 hence forms a possibly cone-shaped flange on the tube 9.
• the circumference of the enclosure 5 may further comprise one or several additional openings, and in the illustrated example it comprises three equidistant openings 12a-c along the circumference of the enclosure 5.
• the tube 9 is here made of a temperature resistant material with low mass and lower or equal thermal expansion than the surroundings, e.g. Alsint ceramics, thin aluminum, or filled heat resistant polymers, the filling being present to reduce the coefficient of thermal expansion (CTE).
• a temperature resistant material with low mass and lower or equal thermal expansion than the surroundings, e.g. Alsint ceramics, thin aluminum, or filled heat resistant polymers, the filling being present to reduce the coefficient of thermal expansion (CTE).
• a typical example of a loudspeaker which can be arranged to meet and exceed the jet formation criterion is PHILIPS/NXP 2403-254-22002.
• the jet formation criterion for round apertures can be found in "Formation Criterion for synthetic jets", Ryan Holman et al., AIAA Journal, 43, 2110-2116, 2005.
• Each opening may be tapered toward the interior of the enclosure in order to boost the internal jet. Further, the edges of each aperture are preferably sharp to promote vortex shedding.
• the flange of the tube 9 is arranged to be moved by the loudspeaker coil 6.
• the reciprocating movement of the loudspeaker results in a translational motion of the flange 11 of the tube 9 which results in an air displacement within the enclosure 5.
• the heat is dissipated from the heat spreading element 2 by actively leading the heated air through the opening 13 in the form of a jet toward the outside of the enclosure 5, i.e. by means of forced convection. Additional flow may be generated via the additional openings 12a-c in the enclosure.
• the surface of the flange of the tube 9 as well as the membrane 7 pumps the air that forms this flow as well as the jet through the actuated opening 13.
• FIG. 2 another example of a cooling arrangement 20 which functions as a double action pump is schematically shown.
• the loudspeaker membrane 7 divides the compartment of the arrangement so that a sub compartment 21, 22 is formed on each side of the membrane 7.
• the openings 12a-c in the circumference of the enclosure 5 lead to the first sub compartment 21 on one side of the loudspeaker membrane 7, whereas a second sub compartment 22 is formed on the opposite side of the loudspeaker membrane 7, at the backside of the loudspeaker.
• the arrangement can work as a double action pump, on condition that there are openings that lead from both sub compartments 21, 22.
• an opening 23 is therefore arranged in the wall of the enclosure 5 and leads to the second sub compartment 22.
• the opening 23 from the second sub compartment 22 is further attached to a n ⁇ -pipe 24, with length n ⁇ , where n is a natural number and ⁇ is the wave length of the waves generated by the loudspeaker.
• the second end of the n ⁇ -pipe 24 is attached to the first sub compartment 21 via one of the additional openings 12c in the circumference of the enclosure.
• the pipe may be a (n+/4) ⁇ -pipe (the length is not to scale).
• the air flow arrow through the opening 12c in pipe 24 changes direction.
• the person skilled in the art realizes that the present invention is not limited to the preferred embodiments.
• other gases (fluids) than air may be pumped.
• the openings may have any shape, such as round, square or oblique, and the number of additional openings is flexible.
• the actuator may be arranged outside the enclosure, but still be in connection with the annular member to achieve the reciprocating movement of it, which may promote lower operating temperatures of the actuator without the need to perforate the magnet.
• the apertures may for example be arranged in the circumference of the heat sink instead of in the enclosure, or in a tube attached to the loudspeaker coil, or even in the loudspeaker membrane.
• the opening may be arranged parallel to the heat spreader, which may allow more length available for an internal jet to develop.
• the arrangement may comprise more than one annular member, actuated by the same actuator.

Landscapes

• Engineering & Computer Science (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Computer Hardware Design (AREA)
• Power Engineering (AREA)
• Physics & Mathematics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• General Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Cooling Or The Like Of Electrical Apparatus (AREA)
• Cooling Or The Like Of Semiconductors Or Solid State Devices (AREA)

Priority Applications (1)

Applications Claiming Priority (3)

Publications (1)

Family

ID=41467200

Family Applications (1)

Country Status (8)

Families Citing this family (12)

Family Cites Families (17)

• 2009
  • 2009-10-12 EP EP09740987A patent/EP2340558A1/de not_active Withdrawn
  • 2009-10-12 JP JP2011531610A patent/JP2012506141A/ja not_active Withdrawn
  • 2009-10-12 US US13/124,427 patent/US20110240260A1/en not_active Abandoned
  • 2009-10-12 CN CN2009801411357A patent/CN102187457A/zh active Pending
  • 2009-10-12 RU RU2011119607/28A patent/RU2011119607A/ru not_active Application Discontinuation
  • 2009-10-12 WO PCT/IB2009/054468 patent/WO2010044047A1/en active Application Filing
  • 2009-10-12 KR KR1020117011227A patent/KR20110073582A/ko not_active Application Discontinuation
  • 2009-10-14 TW TW098134818A patent/TW201027023A/zh unknown

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events