US20010037880A1 - Valved heat pipe and adaptive cooling system including the same - Google Patents
Valved heat pipe and adaptive cooling system including the same Download PDFInfo
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- US20010037880A1 US20010037880A1 US09/476,792 US47679299A US2001037880A1 US 20010037880 A1 US20010037880 A1 US 20010037880A1 US 47679299 A US47679299 A US 47679299A US 2001037880 A1 US2001037880 A1 US 2001037880A1
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- Prior art keywords
- valve
- heat pipe
- temperature
- cooling system
- heat
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- 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
- H01L23/427—Cooling by change of state, e.g. use of heat pipes
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
- F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
- F28D15/0275—Arrangements for coupling heat-pipes together or with other structures, e.g. with base blocks; Heat pipe cores
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
- F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
- F28D15/06—Control arrangements therefor
-
- 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 invention is directed toward the field of heat pipes, and more particularly to the field of valved heat pipes as well as adaptive cooling systems (especially for electrical circuits) including the same.
- Heat pipes are known cooling devices.
- a heat pipe is a pipe that has been sealed at both ends and then evacuated. A small amount of working fluid is introduced into the pipe and the pipe is resealed. If heat is applied to one end of the heat pipe, which is referred to as the evaporator end, then the fluid vaporizes and carries the heat of vaporization in the vapor very quickly to the other end, known as the condenser end. At the condenser end, the latent heat of vaporization is released as the vapor condenses back into liquid form on the condenser end, which it was at a lower temperature then the evaporator end prior to the condensation. The condensed liquid is then carried back to the evaporation end by capillary action and/or gravity.
- heat pipes have very high thermal conductivity because they use convection in addition to conduction.
- a source of heat at the evaporator end is an electrical device, such as a transistor mounted to an internal base.
- the condenser end is typically thermally connected to a heat sink such as a finned metal external structure.
- the heat sink is either actively cooled by a fan or passively cooled by convection on the surface of the package.
- FIG. 1 depicts a Background Art heat pipe-based cooling system.
- the Background Art heat pipe-based cooling system 100 of FIG. 1 includes an electrical circuit 102 mounted on a thermally conductive base plate 104 .
- a heat pipe 108 is connected to the base plate 104 and also to a finned heat sink 106 .
- the heat pipe 108 has a 90° bend 110 .
- the base plate 104 is maintained in a horizontal orientation.
- a foot portion 112 of the heat pipe 108 is also horizontal while a leg portion 114 is substantially vertical. This orientation uses gravity to promote the return of condensed liquid from the condenser end 116 to the evaporator end 118 .
- FIG. 2 is a front view of the pipe 108 , in contrast to the three-quarter perspective view of FIG. 1. As such, the 90° bend 110 of the heat pipe 108 is less discernable in FIG. 2 than in FIG. 1.
- the heat pipe 108 contains liquid 202 that is pooled in the foot portion 112 . Some gaseous molecules 204 of the liquid 202 are depicted as having moved, or moving, toward the condenser end 116 of the leg portion 114 .
- the type of liquid 202 and the internal pressure within the heat pipe 108 are chosen carefully with respect to the operational temperature of the circuitry 102 .
- the change of state temperature (from liquid to vapor) is engineered such that it is between the temperature of the base plate 104 and the temperature of the heat sink.
- the liquid 202 boils at the base plate or evaporator end 118 of the heat pipe 108 , absorbing heat.
- the vapor rises towards the heat sink or condenser end 116 , and then condenses at the lower external heat sink temperature, releasing the heat. Then the liquid falls to recycle or pool at the evaporator end 118 .
- the phase state change improves the cooling efficiency of the heat pipe 108 .
- the performance of the heat pipe will vary as a function of temperature. At very low temperatures, the liquid 202 may freeze into a solid, leaving the conductivity of the external surface of the heat pipe 108 as the only heat flow mechanism, thus lowering the effective conductivity. At low temperatures, most of the liquid 202 may remain in the liquid state, leaving only a small portion of gaseous material to perform convection.
- the invention in part, provides a mechanism to control the rate of heat flow to be proportional to the cooling needs of the active devices.
- a mechanism can cool a target at an adaptive cooling rate.
- a high thermal effective conductivity is provided to maximize the cooling rate despite the lower temperature differential between base plate and heat sink.
- a lower effective thermal conductivity is provided to prevent over cooling the base plate, i.e., to prevent allowing it to drop to a very low temperature.
- the invention limits the cooling rate and allows the base plate temperature to stabilize at a higher temperature, thus limiting the total base plate's temperature cycle.
- the invention also provides, in part, an adaptive circuit cooling system.
- a cooling system comprises: heat generating equipment, e.g., electronic circuitry; a heat sink; and a heat pipe that thermally connects the circuitry to the heat sink.
- the heat pipe includes at least one valve that operates as a function of temperature.
- the invention also provides, in part, a valved heat pipe comprising: a sealed tube; liquid in said tube; and at least one valve in the tube that operates as a function of temperature to selectively obstruct circulation of the liquid from one end of the tube to the other.
- FIG. 1 is a three-quarter perspective view of a cooling system employing a heat pipe according to the Background Art.
- FIG. 2 is a front view of the heat pipe of FIG. 1.
- FIG. 3A is a three-quarter perspective view of an embodiment of a cooling system employing a heat pipe according to the invention.
- FIG. 3B is a front view of the heat pipe of FIG. 3A where the valve is closed.
- FIG. 3C is a front view of the heat pipe of FIG. 3A where the valve is open.
- FIG. 3A is a three-quarter perspective view of an embodiment of a cooling system employing the heat pipe according to the invention.
- heat generating equipment e.g., electronic circuitry such as radio frequency transmitters and/or receivers
- a heat pipe 301 thermally connects the base plate 104 to a heat sink 106 .
- the heat pipe 301 has approximately 90 bend 324 that divides the heat pipe 301 into a foot portion 320 and a leg portion 322 .
- the base plate 104 and therefore the foot 320 , can be oriented so as to be horizontal, thus making the leg portion 322 substantially vertical. Again, this takes advantage of gravity to assist in the recirculation of fluid condensed at a condenser 328 back to an evaporator and 326 .
- the heat pipe 301 includes a valve 302 that can take on a closed state as in FIG. 3B or an open state as in FIG. 3C.
- FIGS. 3B and 3C are front views that contrast with the three-quarter perspective view of FIG. 3A. As such, the 90 bend 324 in FIGS. 3B and 3C is less discernable than in FIG. 3A.
- the valve 302 takes the form of a valve that is either completely open or completely closed based upon a temperature to which the valve is exposed.
- An example of such a valve is a bimetallic valve.
- bimetallic valves are known such that no further discussion of the bimetallic valve technology is needed.
- the valve 302 is a passive device.
- valve 302 can also be described as a binary valve in the sense that it is either completely open or completely closed.
- valve 302 can be a continuously variable valve in the sense that the size of the orifice can vary according to variations in the temperature to which the valve is exposed.
- FIG. 3B is a front view of the heat pipe 301 of FIG. 3A.
- the valve 302 is closed, which obstructs the circulation of the liquid 202 between the evaporator end 326 and the condenser end 328 .
- Gaseous molecules 305 are shown as rising above the 90 bend 324 , but they are blocked by the valve 302 from moving any closer to the condenser end 328 .
- FIG. 3C (again, a front view) depicts the valve 302 in its opened state. There, most of the gas has risen above the valve 302 as depicted by the molecules 307 though there remain some molecules 305 below the valve 302 .
- the valve 302 no longer obstructs circulation of the gas and liquid from the evaporator end 326 to the condenser end 328 and vice-versa.
- valve 302 When the ambient temperature is high, the valve 302 will open so that cooling rate is maximized. At a low ambient temperature, the valve 302 closes, lowering the effective thermal conductivity of the heat pipe 301 .
- FIG. 3A depicts an optional temperature sensor 310 connected to an optional controller 308 via an optional signal line 312 .
- the controller 308 is connected to the valve 302 by the optional signal line 318 .
- an optional temperature sensor 314 is connected to the controller via an optional signal line 316 .
- the valve 302 can be an electrically actuated valve that is driven by the signal on the line 318 .
- the controller 308 Based upon a temperature T 1 sensed by the sensor 310 , or alternatively based upon the temperature T 2 sensed by the temperature sensor 314 , the controller 308 causes the valve 302 to open or close.
- the controller preferably controls the valve 302 to open.
- the controller causes the valve 302 to close.
- the sensor 310 can sense the ambient temperature.
- the sensor 314 can sense the temperature of the base plate 104 .
- Examples of electrically actuated valves are solenoid valves. This will define the system 300 as an active system. Further in the alternative, the valve can be a hydraulically actuated valve, in which case the signal line from the controller 308 is a hydraulic rather than electrical signal line.
- the base plate 104 is typically metallic.
- the circuitry 102 could be mounted on a low thermal conductivity substrate. In that case, then the foot portion of the heat pipe 301 would be directly thermally connected to the circuitry 102 .
- valve 302 has been depicted in the heat pipe 301 according to the invention, for simplicity. But it is to be noted that the invention contemplates at least one valve rather than only one valve.
- a heat pipe might have two or more valves that are either passive or actively controlled. If they are actively controlled by the controller 308 , then these valves can each be controlled according to the same reference temperature or they can each have their own reference temperature. Similarly, more than one such heat pipe can be provided per unit of heat generating equipment.
- the invention has been described in terms of electronic circuitry as an example of the heat generating equipment because such circuitry is well suited to being cooled according to this technology. But the invention can also be applied to other heating generating equipment, e.g., motors or engines.
- valve in the heat pipe has the advantage that it gives the thermal designer more degrees of freedom to design the heat flow rate of the heat pipe then merely the choice of fluid, volume and pressure therein.
- This invention has the advantages that it allows simpler electrical circuits to perform adequately over a large range of ambient temperatures, thus lowering the cost of electrical circuits. Also, it improves reliability by reducing thermal stresses caused by repetitive thermal cycling. It allows high efficiency heat pipes to be used in packages that may be exposed to very cold external ambient environments, yet still maintain a usable internal temperature by not overcooling at low temperatures. As such, it can eliminate the use of heaters to allow operation at cold temperatures, as the active devices' own thermal dissipation may be enough to maintain an adequate operational temperature. It also allows the design of totally passive cooling equipment, improving reliability of the cooling system, which is usually one of the dominant limiting factors. Additional advantages of the invention are that it makes possible the use of passively controlled, or actively controlled, heat pipe-based cooling mechanisms.
- thermal regulating alternatives require a heater, a fan, an active heat pump, an air conditioner, or more than one active system, to help maintain a constant temperature.
- the invention also furthers the development of more complex, temperature compensated systems circuits that can perform adequately over a very large temperature range.
Abstract
A valved heat pipe and an adaptive circuit cooling system using it are disclosed. The valved heat pipe includes a sealed tube, liquid in the tube, and at least one valve in the tube. This valve operates as a function of temperature to selectively obstruct circulation of the liquid from one end of the tube to the other. The adaptive cooling system includes heat generating equipment, e.g., electronic circuitry such as radio frequency transmitters and/or recievers, a heat sink and such a valved heat pipe that thermally connects the circuitry to the heat sink.
Description
- The invention is directed toward the field of heat pipes, and more particularly to the field of valved heat pipes as well as adaptive cooling systems (especially for electrical circuits) including the same.
- Heat pipes are known cooling devices. A heat pipe is a pipe that has been sealed at both ends and then evacuated. A small amount of working fluid is introduced into the pipe and the pipe is resealed. If heat is applied to one end of the heat pipe, which is referred to as the evaporator end, then the fluid vaporizes and carries the heat of vaporization in the vapor very quickly to the other end, known as the condenser end. At the condenser end, the latent heat of vaporization is released as the vapor condenses back into liquid form on the condenser end, which it was at a lower temperature then the evaporator end prior to the condensation. The condensed liquid is then carried back to the evaporation end by capillary action and/or gravity.
- Thus, heat pipes have very high thermal conductivity because they use convection in addition to conduction.
- Typically, a source of heat at the evaporator end is an electrical device, such as a transistor mounted to an internal base. The condenser end is typically thermally connected to a heat sink such as a finned metal external structure. The heat sink is either actively cooled by a fan or passively cooled by convection on the surface of the package. There is a temperature differential between the internal base plate and the external heat sink that drives the heat pipe's convection process. FIG. 1 depicts a Background Art heat pipe-based cooling system.
- The Background Art heat pipe-based
cooling system 100 of FIG. 1 includes anelectrical circuit 102 mounted on a thermallyconductive base plate 104. Aheat pipe 108 is connected to thebase plate 104 and also to afinned heat sink 106. Theheat pipe 108 has a 90°bend 110. Typically, thebase plate 104 is maintained in a horizontal orientation. As such, afoot portion 112 of theheat pipe 108 is also horizontal while aleg portion 114 is substantially vertical. This orientation uses gravity to promote the return of condensed liquid from the condenser end 116 to theevaporator end 118. - The
heat pipe 108 is depicted in more detail in Background Art FIG. 2. FIG. 2 is a front view of thepipe 108, in contrast to the three-quarter perspective view of FIG. 1. As such, the 90°bend 110 of theheat pipe 108 is less discernable in FIG. 2 than in FIG. 1. In FIG. 2, theheat pipe 108 containsliquid 202 that is pooled in thefoot portion 112. Somegaseous molecules 204 of theliquid 202 are depicted as having moved, or moving, toward thecondenser end 116 of theleg portion 114. - For optimal performance of the
cooling system 100, the type ofliquid 202 and the internal pressure within theheat pipe 108 are chosen carefully with respect to the operational temperature of thecircuitry 102. Ideally, the change of state temperature (from liquid to vapor) is engineered such that it is between the temperature of thebase plate 104 and the temperature of the heat sink. The liquid 202 boils at the base plate or evaporator end 118 of theheat pipe 108, absorbing heat. The vapor rises towards the heat sink orcondenser end 116, and then condenses at the lower external heat sink temperature, releasing the heat. Then the liquid falls to recycle or pool at theevaporator end 118. The phase state change improves the cooling efficiency of theheat pipe 108. - The performance of the heat pipe will vary as a function of temperature. At very low temperatures, the
liquid 202 may freeze into a solid, leaving the conductivity of the external surface of theheat pipe 108 as the only heat flow mechanism, thus lowering the effective conductivity. At low temperatures, most of theliquid 202 may remain in the liquid state, leaving only a small portion of gaseous material to perform convection. - At higher temperatures, a greater portion of the
liquid 202 may be involved in the phase change cycle. This is the maximum cooling rate. At an even higher temperature, all of theliquid 202 may remain in the gaseous state, thus lowering the efficiency of theheat pipe 108, as there is no phase state change. Thus, the range of operational temperature and the chemical make-up of the fluid may be constrained. Also, the effective conductivity of theheat pipe 108 may vary as a function of temperature, but not in a very controlled manner. - Regular thermal conduction through a metal works best when there is a large temperature differential between the base plate (the source) and the heat sink. Thus, the fastest (best) cooling rate occurs when the ambient temperature is low and the
base plate 104 temperature is high. Likewise, the slowest (worst) cooling rate occurs when the heat sink 106 temperature (external ambient) is high, approaching that of theinternal base plate 104 temperature, leaving a small differential. In order to achieve adequate cooling at these high ambient temperatures, the conduction path orheat pipe 104 size must be made large enough to function adequately at the low temperature differential. Thus, there is excess cooling capacity at lower ambient temperatures, and thebase plate 104 temperature will vary widely as a function of the external ambient temperature. Temperature differentials drive the phase state cycle in aheat pipe 108. - Problems with a wide temperature differential at the base plate are that it stresses both the mechanical packaging technology and the electrical performance of the
circuitry 102. The electrical performance of transistor circuits, especially for RF amplification, will vary widely as a function of temperature. Because many of these RF circuits cannot apply conventional negative feedback, which is commonly used at lower frequencies, excess gain cannot be designed in and used to stabilize the circuit's performance. Thus other, more complex open loop or closed loop sensing schemes must be used to compensate for device gain changes as a function of temperature. This requires additional temperature or power detector circuits, and can be quite complex, and may require calibration. From an electrical point of view, operation at a constant temperature would simplify the circuit design immensely, as the gain would not vary. - Mechanically, many failure mechanisms are due to material differentials, such as different rates of thermal expansion and galvanic corrosion. Repetitive thermal cycling is a significant source of aging and may damage many types of connections, such as solder joints, wire bonds, packaging interconnects and other mechanical joints. Elimination of temperature cycling, or lowering the range of differential may significantly lower the failure rate of circuits, particularly power supply and RF amplification circuits. For outdoor mounted equipment, the daytime/nighttime circadian cycle may be the dominant temperature driver.
- The invention, in part, provides a mechanism to control the rate of heat flow to be proportional to the cooling needs of the active devices. Such a mechanism can cool a target at an adaptive cooling rate. At high ambient temperatures, a high thermal effective conductivity is provided to maximize the cooling rate despite the lower temperature differential between base plate and heat sink. At low ambient temperatures, a lower effective thermal conductivity is provided to prevent over cooling the base plate, i.e., to prevent allowing it to drop to a very low temperature. Instead of cooling the circuitry maximally to the lowest differential above the outdoor ambient temperature, the invention limits the cooling rate and allows the base plate temperature to stabilize at a higher temperature, thus limiting the total base plate's temperature cycle.
- The invention also provides, in part, an adaptive circuit cooling system. Such a cooling system comprises: heat generating equipment, e.g., electronic circuitry; a heat sink; and a heat pipe that thermally connects the circuitry to the heat sink. The heat pipe includes at least one valve that operates as a function of temperature.
- The invention also provides, in part, a valved heat pipe comprising: a sealed tube; liquid in said tube; and at least one valve in the tube that operates as a function of temperature to selectively obstruct circulation of the liquid from one end of the tube to the other.
- Objectives of the present invention will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
- The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus do not limit the present invention.
- FIG. 1 is a three-quarter perspective view of a cooling system employing a heat pipe according to the Background Art.
- FIG. 2 is a front view of the heat pipe of FIG. 1.
- FIG. 3A is a three-quarter perspective view of an embodiment of a cooling system employing a heat pipe according to the invention.
- FIG. 3B is a front view of the heat pipe of FIG. 3A where the valve is closed.
- And, FIG. 3C is a front view of the heat pipe of FIG. 3A where the valve is open.
- It is noted that the Drawings are not drawn to scale.
- FIG. 3A is a three-quarter perspective view of an embodiment of a cooling system employing the heat pipe according to the invention.
- Components common to the Background Art will share the same item numbers.
- In the
cooling system 300 of FIG. 3A, heat generating equipment, e.g., electronic circuitry such as radio frequency transmitters and/or receivers, 102 is formed on abase plate 104. Aheat pipe 301 thermally connects thebase plate 104 to aheat sink 106. Similar to the Background Art, theheat pipe 301 has approximately 90bend 324 that divides theheat pipe 301 into afoot portion 320 and aleg portion 322. Thebase plate 104, and therefore thefoot 320, can be oriented so as to be horizontal, thus making theleg portion 322 substantially vertical. Again, this takes advantage of gravity to assist in the recirculation of fluid condensed at acondenser 328 back to an evaporator and 326. - In contrast to the Background
Art heat pipe 108, theheat pipe 301 includes avalve 302 that can take on a closed state as in FIG. 3B or an open state as in FIG. 3C. FIGS. 3B and 3C are front views that contrast with the three-quarter perspective view of FIG. 3A. As such, the 90bend 324 in FIGS. 3B and 3C is less discernable than in FIG. 3A. - At its most simple, the
valve 302 takes the form of a valve that is either completely open or completely closed based upon a temperature to which the valve is exposed. An example of such a valve is a bimetallic valve. Generally, bimetallic valves are known such that no further discussion of the bimetallic valve technology is needed. In this simple form, thevalve 302 is a passive device. - The simple form of the
valve 302 can also be described as a binary valve in the sense that it is either completely open or completely closed. Alternatively, thevalve 302 can be a continuously variable valve in the sense that the size of the orifice can vary according to variations in the temperature to which the valve is exposed. - It is noted that it is unnecessary to provide a fan to force air across the
heat sink 106 of thecooling system 300 because of the efficiency of this system. This eliminates moving parts, which greatly improves reliability. - FIG. 3B is a front view of the
heat pipe 301 of FIG. 3A. In FIG. 3B, thevalve 302 is closed, which obstructs the circulation of the liquid 202 between theevaporator end 326 and thecondenser end 328.Gaseous molecules 305 are shown as rising above the 90bend 324, but they are blocked by thevalve 302 from moving any closer to thecondenser end 328. In contrast, FIG. 3C (again, a front view) depicts thevalve 302 in its opened state. There, most of the gas has risen above thevalve 302 as depicted by themolecules 307 though there remain somemolecules 305 below thevalve 302. In FIG. 3C, thevalve 302 no longer obstructs circulation of the gas and liquid from theevaporator end 326 to thecondenser end 328 and vice-versa. - When the ambient temperature is high, the
valve 302 will open so that cooling rate is maximized. At a low ambient temperature, thevalve 302 closes, lowering the effective thermal conductivity of theheat pipe 301. - In FIG. 3A, some optional elements are depicted in broken lines. In particular, FIG. 3A depicts an
optional temperature sensor 310 connected to anoptional controller 308 via anoptional signal line 312. Thecontroller 308 is connected to thevalve 302 by the optional signal line 318. As an alternative to thetemperature sensor 310, anoptional temperature sensor 314 is connected to the controller via anoptional signal line 316. - When the
controller 308 is present, thevalve 302 can be an electrically actuated valve that is driven by the signal on the line 318. Based upon a temperature T1 sensed by thesensor 310, or alternatively based upon the temperature T2 sensed by thetemperature sensor 314, thecontroller 308 causes thevalve 302 to open or close. When the sensed temperature T1 or T2 is greater than or equal to a reference temperature, the controller preferably controls thevalve 302 to open. When the temperature falls below the reference value, the controller causes thevalve 302 to close. By being positioned against theheat sink 106, thesensor 310 can sense the ambient temperature. Thesensor 314 can sense the temperature of thebase plate 104. - Examples of electrically actuated valves are solenoid valves. This will define the
system 300 as an active system. Further in the alternative, the valve can be a hydraulically actuated valve, in which case the signal line from thecontroller 308 is a hydraulic rather than electrical signal line. - The
base plate 104 is typically metallic. Alternatively, thecircuitry 102 could be mounted on a low thermal conductivity substrate. In that case, then the foot portion of theheat pipe 301 would be directly thermally connected to thecircuitry 102. - Only one
valve 302 has been depicted in theheat pipe 301 according to the invention, for simplicity. But it is to be noted that the invention contemplates at least one valve rather than only one valve. For example, a heat pipe might have two or more valves that are either passive or actively controlled. If they are actively controlled by thecontroller 308, then these valves can each be controlled according to the same reference temperature or they can each have their own reference temperature. Similarly, more than one such heat pipe can be provided per unit of heat generating equipment. - The invention has been described in terms of electronic circuitry as an example of the heat generating equipment because such circuitry is well suited to being cooled according to this technology. But the invention can also be applied to other heating generating equipment, e.g., motors or engines.
- The provision of a valve in the heat pipe has the advantage that it gives the thermal designer more degrees of freedom to design the heat flow rate of the heat pipe then merely the choice of fluid, volume and pressure therein.
- This invention has the advantages that it allows simpler electrical circuits to perform adequately over a large range of ambient temperatures, thus lowering the cost of electrical circuits. Also, it improves reliability by reducing thermal stresses caused by repetitive thermal cycling. It allows high efficiency heat pipes to be used in packages that may be exposed to very cold external ambient environments, yet still maintain a usable internal temperature by not overcooling at low temperatures. As such, it can eliminate the use of heaters to allow operation at cold temperatures, as the active devices' own thermal dissipation may be enough to maintain an adequate operational temperature. It also allows the design of totally passive cooling equipment, improving reliability of the cooling system, which is usually one of the dominant limiting factors. Additional advantages of the invention are that it makes possible the use of passively controlled, or actively controlled, heat pipe-based cooling mechanisms. Most thermal regulating alternatives require a heater, a fan, an active heat pump, an air conditioner, or more than one active system, to help maintain a constant temperature. The invention also furthers the development of more complex, temperature compensated systems circuits that can perform adequately over a very large temperature range.
- The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
Claims (19)
1. An adaptive cooling system comprising:
heat generating equipment;
a heat sink; and
a heat pipe thermally connecting said heat generating equipment to said heat sink;
wherein said heat pipe includes at least one valve that operates as a function of temperature.
2. The cooling system of , wherein said at least one valve is open or closed based upon a temperature to which said at least one valve is exposed.
claim 1
3. The cooling system of , wherein said at least one valve is a bimetallic device.
claim 2
4. The cooling system of , further comprising:
claim 1
a temperature sensor; and
a controller for receiving a signal indicative of temperature from said temperature sensor;
wherein said at least one valve is actuated by at least one control signal from said controller, respectively; and
wherein said controller is operable to cause said at least one valve to open when said temperature signal is greater than or equal to a corresponding reference value, respectively.
5. The cooling system of , wherein said at least one control signal is electrical and said at least one valve is a solenoid valve.
claim 4
6. The cooling system of , further comprising a thermally conductive substrate, wherein said circuitry is mounted to said substrate and said heat pipe is thermally connected to said substrate such that heat from said circuitry is transferred to said heat pipe via said substrate.
claim 1
7. The cooling system of , wherein said substrate is metallic.
claim 6
8. An adaptive electronic circuit cooling system comprising:
electronic circuitry;
a heat sink; and
a heat pipe thermally connecting said circuitry to said heat sink;
wherein said heat pipe includes at least one valve that operates as a function of temperature.
9. The cooling system of , wherein said at least one valve is open or closed based upon a temperature to which said at least one valve is exposed.
claim 8
10. The cooling system of , wherein said at least one valve is a bimetallic device.
claim 9
11. The cooling system of , further comprising:
claim 8
a temperature sensor; and
a controller for receiving a signal indicative of temperature from said temperature sensor;
wherein said at least one valve is actuated by at least one control signal from said controller, respectively; and
wherein said controller is operable to cause said at least one valve to open when said temperature signal is greater than or equal to a corresponding reference value, respectively.
12. The cooling system of , wherein said at least one control signal is electrical and said at least one valve is a solenoid valve.
claim 11
13. The cooling system of , further comprising a thermally conductive substrate, wherein said circuitry is mounted to said substrate and said heat pipe is thermally connected to said substrate such that heat from said circuitry is transferred to said heat pipe via said substrate.
claim 8
14. The cooling system of , wherein said substrate is metallic.
claim 13
15. A valved heat pipe comprising:
a sealed tube;
liquid in said tube; and
at least one valve in said tube operates as a function of temperature to selectively obstruct circulation of said liquid from one end of said tube to the other.
16. The heat pipe of , wherein said at least one valve is open or closed based upon a temperature to which said at least one valve is exposed.
claim 15
17. The heat pipe of , wherein said at least one valve is a bimetallic device.
claim 16
18. The heat pipe of , wherein said at least one valve is actuated by a control signal from a controller.
claim 8
19. The heat pipe of , wherein said control signal is electrical and said at least one valve is a solenoid valve.
claim 18
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US09/476,792 US20010037880A1 (en) | 1999-12-30 | 1999-12-30 | Valved heat pipe and adaptive cooling system including the same |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/476,792 US20010037880A1 (en) | 1999-12-30 | 1999-12-30 | Valved heat pipe and adaptive cooling system including the same |
Publications (1)
Publication Number | Publication Date |
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US20010037880A1 true US20010037880A1 (en) | 2001-11-08 |
Family
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US09/476,792 Abandoned US20010037880A1 (en) | 1999-12-30 | 1999-12-30 | Valved heat pipe and adaptive cooling system including the same |
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Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20090203082A1 (en) * | 2005-04-04 | 2009-08-13 | Thomas Schlaubitz | Thermocycling of a Block Comprising Multiple Sample |
JP2011220633A (en) * | 2010-04-12 | 2011-11-04 | Fujikura Ltd | Cooling device for data center |
US20120222444A1 (en) * | 2009-09-03 | 2012-09-06 | Huawei Technologies Co., Ltd. | Remote radio unit |
US8840034B2 (en) | 2011-06-10 | 2014-09-23 | International Business Machines Corporation | Automatic in situ coolant flow control in LFT heat exchanger |
US20150109737A1 (en) * | 2012-06-29 | 2015-04-23 | Toshiba Mitsubishi-Electric Ind. Systems Corp. | Power conversion apparatus |
US9271429B2 (en) | 2010-04-12 | 2016-02-23 | Fujikura Ltd. | Cooling device, cooling system, and auxiliary cooling device for datacenter |
US20180080720A1 (en) * | 2015-10-13 | 2018-03-22 | International Business Machines Corporation | Demand-based charging of a heat pipe |
US20190040969A1 (en) * | 2017-08-03 | 2019-02-07 | Fluke Corporation | Temperature calibration system comprising a valve in a closed fluidic system |
-
1999
- 1999-12-30 US US09/476,792 patent/US20010037880A1/en not_active Abandoned
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20090203082A1 (en) * | 2005-04-04 | 2009-08-13 | Thomas Schlaubitz | Thermocycling of a Block Comprising Multiple Sample |
US20120222444A1 (en) * | 2009-09-03 | 2012-09-06 | Huawei Technologies Co., Ltd. | Remote radio unit |
JP2011220633A (en) * | 2010-04-12 | 2011-11-04 | Fujikura Ltd | Cooling device for data center |
US9271429B2 (en) | 2010-04-12 | 2016-02-23 | Fujikura Ltd. | Cooling device, cooling system, and auxiliary cooling device for datacenter |
US8840034B2 (en) | 2011-06-10 | 2014-09-23 | International Business Machines Corporation | Automatic in situ coolant flow control in LFT heat exchanger |
US9392728B2 (en) | 2011-06-10 | 2016-07-12 | Lenovo Enterprise Solutions (Singapore) Pte. Ltd. | Automatic in situ coolant flow control in LFT heat exchanger |
US20150109737A1 (en) * | 2012-06-29 | 2015-04-23 | Toshiba Mitsubishi-Electric Ind. Systems Corp. | Power conversion apparatus |
US9661785B2 (en) * | 2012-06-29 | 2017-05-23 | Toshiba Mitsubishi-Electric Industrial Systems Corporation | Power conversion apparatus |
US20180080720A1 (en) * | 2015-10-13 | 2018-03-22 | International Business Machines Corporation | Demand-based charging of a heat pipe |
US10982907B2 (en) * | 2015-10-13 | 2021-04-20 | International Business Machines Corporation | Demand-based charging of a heat pipe |
US20190040969A1 (en) * | 2017-08-03 | 2019-02-07 | Fluke Corporation | Temperature calibration system comprising a valve in a closed fluidic system |
US10677369B2 (en) * | 2017-08-03 | 2020-06-09 | Fluke Corporation | Temperature calibration system comprising a valve in a closed fluidic system |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: LUCENT TECHNOLOGIES INC., NEW JERSEY Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SOLONDZ, MAX AARON;REEL/FRAME:010486/0404 Effective date: 19991218 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |