Efficient cooling system for high-frequency millimeter-wave radar for vehicle

Abstract

The invention, which relates to the technical field of radar heat dissipation, discloses a high-efficiency heat dissipation system for a vehicle high-frequency millimeter-wave radar, and the system comprises a heat conduction module, a heat storage module, a convection heat dissipation module, and a sealing protection module. According to the invention, the heat conduction module utilizes a high-heat-conduction material and a metal interconnection structure to quickly conduct out heat generated by the radar chip, so that the temperature of a heat source is effectively reduced. The heat storage module absorbs and stores a large amount of heat energy through a phase change material, the temperature rise is buffered during instantaneous high load, and the temperature distribution in the system tends to be uniform by means of a soaking structure. The convection heat dissipation module adopts a passive heat dissipation design, and heat is continuously dissipated to the surrounding environment through natural convection by increasing the contact area with air. And the sealing protection module compensates thermal stress caused by temperature change while realizing system sealing through elastic sealing and a flexible heat conduction material, so that the reliability of the system in a wide temperature range environment is ensured.

Description

Technical Field

[0001] This invention relates to the field of radar heat dissipation technology, and in particular to a high-efficiency heat dissipation system for automotive high-frequency millimeter-wave radar. Background Technology

[0002] High-frequency millimeter-wave radar is a core sensor in automotive intelligent driving systems. By transmitting and receiving high-frequency millimeter waves, it enables precise distance measurement, speed measurement, target recognition, and trajectory tracking of the vehicle's surroundings, providing environmental perception capabilities for intelligent driving functions such as adaptive cruise control, automatic emergency braking, and lane keeping.

[0003] Currently, the heat dissipation system of automotive millimeter-wave radar suffers from problems such as low thermal conductivity leading to heat accumulation, lack of effective buffering against instantaneous high thermal loads resulting in excessive internal temperature differences, insufficient passive heat dissipation capacity making it difficult to continuously dissipate heat, and the sealing structure being prone to failure due to thermal stress in a wide temperature range. These issues collectively affect the radar's operational reliability, heat dissipation efficiency, and service life.

[0004] Therefore, a high-efficiency heat dissipation system for automotive high-frequency millimeter-wave radar is proposed to solve the above problems. Summary of the Invention

[0005] The main objective of this invention is to provide an efficient heat dissipation system for high-frequency millimeter-wave radar used in vehicles, in order to solve the problems mentioned in the background above.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a high-efficiency heat dissipation system for automotive high-frequency millimeter-wave radar, the system comprising a heat conduction module, a heat storage module, a convection heat dissipation module, and a sealing and protection module;

[0007] The heat-conducting module rapidly removes heat from the chip's heat source through a highly thermally conductive material and a metal interconnect structure, a process that follows Fourier's law.

[0008] The thermal storage module utilizes phase change materials to absorb and store a large amount of latent heat during the phase transition, so as to buffer instantaneous high heat loads, and makes the internal temperature field of the system uniform through a heat equalization structure.

[0009] The convection heat dissipation module increases the contact area with the air through a passive heat dissipation structure, and uses natural air convection to continuously dissipate heat into the environment. The heat flow rate of this process is determined by Newton's law of cooling.

[0010] The sealing and protection module uses an elastic sealing material to achieve static sealing under compression, and uses a flexible thermally conductive material to compensate for the stress caused by the mismatch of thermal expansion coefficients between different components.

[0011] Preferably, the thermally conductive module includes a high thermal conductivity composite substrate unit and a metallized thermal connection unit;

[0012] The high thermal conductivity composite substrate unit is composed of a metal core layer and a carbon-based high thermal conductivity layer.

[0013] The metallized thermal connection unit includes an array of vias penetrating the substrate, and its thermal conductivity is described by the Fourier law: ,in For heat flux density, The thermal conductivity of the material For temperature gradient.

[0014] Preferably, the carbon-based high thermal conductivity layer of the high thermal conductivity composite substrate unit is a graphene layer with high orientation.

[0015] Preferably, the thermal storage module includes a phase change thermal storage unit and a heat spreader fin unit;

[0016] The phase change thermal storage unit is filled with an organic-inorganic composite phase change material, and its total thermal storage capacity is given by the formula. Description, in which Total latent heat, For the quality of phase change materials, Latent heat of phase transition;

[0017] The heat exchange fin unit extends into the phase change material to increase the heat exchange area.

[0018] Preferably, the organic-inorganic composite phase change material contains dispersed nano-ceramic particles, and the surface of the heat-dampening fin unit is treated with micro-nano structures to enhance its wettability with the phase change material.

[0019] Preferably, the convection heat dissipation module includes a high-density toothed fin unit and a passive heat transfer enhancement unit;

[0020] The high-density toothed fin unit enhances heat dissipation by increasing the heat dissipation surface area. Its heat dissipation efficiency is proportional to the surface area and follows Newton's law of cooling. ,in The convective heat transfer coefficient is... The surface temperature for heat dissipation. Ambient temperature;

[0021] The passive heat transfer enhancement unit is a microchannel structure disposed on the fin surface, which disturbs airflow to improve the convective heat transfer coefficient. .

[0022] Preferably, the surface of the high-density toothed fin unit is coated with an oxide layer;

[0023] The oxide layer is formed by anodizing the surface of aluminum alloy after extrusion molding.

[0024] Preferably, the sealing protection module includes a compression compensation sealing unit and a thermal expansion compensation unit;

[0025] The compression compensation sealing unit uses an elastomer sealing ring, which achieves sealing through a preset compression amount;

[0026] The thermal expansion compensation unit uses a flexible thermally conductive pad, and its thermal expansion is calculated by the formula... Calculation, where The coefficient of thermal expansion is For the initial length, This represents the temperature change, absorbing the thermal displacement between assemblies.

[0027] Preferably, the compression compensation sealing unit includes a sealing ring and a sealing groove structure, and its sealing principle is based on the elastic deformation behavior of the sealing material; the thermal expansion compensation unit includes a flexible thermally conductive pad and an adhesive layer.

[0028] Preferably, the structural reinforcement unit enhances the overall structural stiffness and natural frequency by adding supporting structures or material reinforcement, so that it meets the preset fatigue life requirements in a mechanical vibration environment, while maintaining heat dissipation performance.

[0029] The present invention has the following beneficial effects:

[0030] 1. In this invention, efficient heat management is achieved through the relay collaboration of heat conduction, heat storage, and convection heat dissipation modules. The heat conduction module quickly draws away the heat generated by the chip; the heat storage module absorbs instantaneous heat shocks, avoids drastic temperature fluctuations, and makes the heat distribution more uniform through the internal temperature equalization structure; finally, the convection heat dissipation module continuously and stably dissipates heat into the air through an optimized structure. These three modules are interlocked and work together to ensure that the radar chip can maintain a stable and suitable temperature range under continuous high load operation.

[0031] 2. In this invention, a robust physical protection is constructed through a sealing and protection module and a structural reinforcement module. The sealing and protection module not only effectively isolates the intrusion of external moisture and dust, but also automatically compensates for the thermal expansion and contraction stress caused by drastic temperature changes, preventing the interface from loosening or cracking due to stress. At the same time, the structural reinforcement module improves the rigidity and vibration resistance of the entire heat dissipation system, enabling it to withstand long-term vibration and impact during vehicle operation. The combination of these two aspects ensures that the heat dissipation system and even the entire radar can work stably and reliably for a long time in the variable and vibrating vehicle environment.

[0032] 3. In this invention, the high-speed heat conduction of the heat conduction module dissipates the instantaneous high heat of the chip, and the heat storage module acts as a buffer to prevent transient thermal shocks from exceeding the immediate processing capacity of the heat conduction and heat dissipation modules. The temperature uniformity of the heat storage module directly benefits from the rapid internal heat distribution network established by the heat conduction module through the heat dissipation fins. The convection heat dissipation module, as the final heat dissipation outlet, ensures the periodic reset and cooling of the heat storage module through its continuous operation, enabling the system to cope with the next round of thermal load. Attached Figure Description

[0033] Figure 1 This is a framework diagram of the high-efficiency heat dissipation system for automotive high-frequency millimeter-wave radar of the present invention;

[0034] Figure 2 This is a schematic diagram of the heat conduction module of the high-efficiency heat dissipation system for high-frequency millimeter-wave radar in vehicles according to the present invention.

[0035] Figure 3 This is a schematic diagram of the heat storage module of the high-efficiency heat dissipation system for high-frequency millimeter-wave radar in vehicles according to the present invention.

[0036] Figure 4 This is a schematic diagram of the convection cooling module of the high-efficiency heat dissipation system for automotive high-frequency millimeter-wave radar of the present invention.

[0037] Figure 5 This is a schematic diagram of the sealed protection module of the high-efficiency heat dissipation system for automotive high-frequency millimeter-wave radar of the present invention. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Please see Figure 1-5 The present invention provides a technical solution: a high-efficiency heat dissipation system for automotive high-frequency millimeter-wave radar, the system comprising a heat conduction module, a heat storage module, a convection heat dissipation module, and a sealing and protection module;

[0040] The thermal module rapidly dissipates heat from the chip's heat source using highly thermally conductive materials and a metal interconnect structure, a process that follows Fourier's law. ,in For heat flux density, The thermal conductivity of the material For temperature gradient;

[0041] The thermal storage module utilizes phase change materials to absorb and store a large amount of latent heat during the phase transition, in order to buffer instantaneous high heat loads, and to make the internal temperature field of the system uniform through a heat equalization structure.

[0042] The convection cooling module increases the contact area with the air through a passive cooling structure, utilizing natural air convection to continuously dissipate heat into the environment. The heat flow rate in this process is determined by Newton's law of cooling. ,in The convective heat transfer coefficient is... The surface temperature for heat dissipation. Ambient temperature;

[0043] The sealing and protection module uses elastic sealing material to achieve static sealing under compression, and uses flexible thermal conductive material to compensate for the stress caused by the mismatch of thermal expansion coefficients between different components.

[0044] The thermally conductive module includes a high thermal conductivity composite substrate unit and a metallized thermal connection unit;

[0045] The high thermal conductivity composite substrate unit is composed of a metal core layer and a carbon-based high thermal conductivity layer;

[0046] Metal core layer: preferably a copper-molybdenum alloy with a thermal conductivity of up to 400 W / (m·K), its thickness accounts for 80% of the total thickness of the substrate. This layer mainly provides mechanical support, ensures structural rigidity, and utilizes the high thermal conductivity of the metal for preliminary lateral heat diffusion.

[0047] Carbon-based high thermal conductivity layer: A multilayer graphene film with a thickness of 15μm and an orientation degree of ≥95% is grown in situ on the metal core layer through plasma-enhanced chemical vapor deposition. This layer is the key to achieving rapid lateral spread.

[0048] The carbon-based high thermal conductivity layer of the high thermal conductivity composite substrate unit is a graphene layer with high orientation.

[0049] The in-plane thermal conductivity of the graphene layer ( The value can reach over 1500 W / (m·K), and through the thickness direction ( With a heat capacity of only about 10 W / (m·K), it exhibits strong anisotropy; when the heat generated by the chip is injected into the graphene layer, its lateral diffusion capability is described by the two-dimensional Fourier law:

[0050] ,in: It is the in-plane heat flux density vector. It is an in-plane temperature gradient; this process can quickly spread the point-like high heat flux density hotspots directly under the chip into a uniform low heat flux density region in a two-dimensional plane, greatly reducing the risk of local high temperature.

[0051] The metallized thermal connection unit is composed of copper vias arranged in an array in the form of BGA. These vias penetrate vertically through the composite substrate to form a high-speed channel directly from the carbon-based high thermal conductivity layer to the thermal storage module.

[0052] The vias have a diameter of 1.0 mm, a center-to-center distance of 3.0 mm, and are arranged in a close-packed hexagonal pattern. The inner wall of the vias is deposited with a titanium-copper composite barrier layer by magnetron sputtering, and then a solid copper filling process is used to ensure that its bulk thermal conductivity is comparable to that of bulk copper.

[0053] The core function of this via array is to construct a vertical heat transfer path with extremely low thermal resistance, and its heat conduction process follows an extended form of the one-dimensional Fourier law:

[0054] ,in For total vertical heat flow, The thermal conductivity of copper, For substrate thickness, The temperature difference between the upper and lower surfaces of the substrate, This is the sum of the cross-sectional areas of all vias;

[0055] For a regular hexagonal arrangement, the percentage of the total cross-sectional area of ​​vias per unit area (i.e., the metallization rate). It can be calculated using the following formula: ,in The diameter of the via is The hole spacing;

[0056] The overall performance of the heat-conducting module can be comprehensively evaluated using an equivalent thermal resistance network model; this model consists of the lateral thermal resistance representing the lateral diffusion of the graphene layer (…). ) and the vertical thermal resistance representing the vertical conduction of the via array ( It is connected in series:

[0057] ;

[0058] in The thickness of the graphene layer. For chip area, The area is the substrate area.

[0059] The thermal storage module includes a phase change thermal storage unit and a heat spreader fin unit;

[0060] The phase change thermal storage unit is filled with organic-inorganic composite phase change material, with fumed silica (SiO2) with a three-dimensional nanoporous structure as the inorganic framework, accounting for 12% by mass. Through melt blending and vacuum impregnation processes, paraffin molecules are adsorbed into the nanopores, thus maintaining a solid shape even in the molten state and preventing leakage.

[0061] Its total heat storage capacity is given by the formula Description, in which Total latent heat, For the effective quality of composite phase change materials, Latent heat of phase transition;

[0062] To address the intermittent high-power operating mode of radar chips, a transient thermal equilibrium model is used:

[0063] ;

[0064] in, For the chip's peak power, For the duration of peak power, For the solid-state specific heat capacity of PCM, For the heat capacity of other components in the module (such as fins, shell), This represents the maximum allowable temperature rise of the system.

[0065] This model allows for precise design. Ensure that Within a certain time, the system temperature will not exceed the standard due to insufficient heat dissipation. The PCM temporarily stores the heat through phase change.

[0066] The heat exchange fin unit extends into the phase change material to increase the heat exchange area;

[0067] This unit is not a traditional external fin, but a tree-like fractal fin made of high thermal conductivity aluminum alloy (aluminum 6061). Its trunk is directly connected to the through-hole array of the heat-conducting module, while the branches extend into the PCM in a fractal structure, maximizing the heat exchange area. ;

[0068] The function of the fins is to construct a low thermal resistance heat-conducting network embedded inside the PCM, overcoming the PCM's inherent poor thermal conductivity; its temperature uniformity can be assessed by its equivalent thermal conductivity (…). The equivalent thermal conductivity can be estimated using the following formula: (The formula is used to characterize the fins and PCM; considering the composite of fins and PCM, the equivalent thermal conductivity can be estimated using the following formula:)

[0069] ;

[0070] in, The thermal conductivity of PCM, For the thermal conductivity of the fins, The volume fraction of fins in the fin-PCM composite system ( ), The interfacial thermal resistance per unit area between the fins and the PCM, The characteristic thickness of the fin;

[0071] By maximizing Heat can be rapidly transferred from the fin backbone to the furthest corners of the PCM, ensuring maximum temperature difference inside the module. satisfy ,in This refers to the internal thermal resistance of the module.

[0072] The organic-inorganic composite phase change material contains nano-ceramic particles, and the surface of the heat-dampening fin unit is treated with micro-nano structures to enhance its wettability with the phase change material.

[0073] In the composite PCM, aluminum nitride (AlN) nanoparticles with a mass percentage of 8% and a particle size of 100 nm are uniformly dispersed. These particles form a high-speed phonon transport network in the PCM, significantly improving the bulk thermal conductivity of the PCM. Its lifting mechanism can be described by the Maxwell-Garnett effective medium theory:

[0074] ;

[0075] in, It is the thermal conductivity of the basic PCM. It is the thermal conductivity of nanoparticles (AlN≈320W / (m·K)). It is the volume fraction of nanoparticles;

[0076] Micro / nano-structured wettability enhancement: A composite structure of micron-level grooves and nano-level fibers is fabricated on the surface of the heat-dampening fins using femtosecond laser processing, followed by hydrophilization treatment to form a superhydrophilic surface, increasing the contact angle with molten PCM. ≤10;

[0077] According to the Young-Laplace equation and the Wenzel model, rough surfaces can significantly enhance wettability:

[0078] ;

[0079] in, The apparent contact angle, The intrinsic contact angle, For surface roughness factor ( >1); Superhydrophilic surface ( The extremely small size brings the following advantages:

[0080] This greatly reduces the thermal resistance at the solid-liquid interface. This makes the heat transfer from the fins to the PCM more efficient;

[0081] This induces the generation of a powerful capillary force, which... Described by the Washburn equation:

[0082] ;

[0083] in The surface tension of the PCM melt. The equivalent pore size of the micro / nano structure;

[0084] The capillary force can actively pump the molten PCM, triggering micro-convection in the phase change interface region (solid-liquid two-phase coexistence region), thereby violently scouring the fin surface, destroying the thermal boundary layer at the interface, and changing the heat transfer from a conduction-dominated mode to a conduction-convection synergistic enhanced mode, further improving the overall heat storage and homogenization rate.

[0085] The convection cooling module includes a high-density toothed fin unit and a passive heat transfer enhancement unit;

[0086] High-density toothed fin units enhance heat dissipation by increasing the heat dissipation surface area. Their heat dissipation efficiency is proportional to the surface area and follows Newton's law of cooling.

[0087] The high-density toothed fin unit is not a traditional equidistant straight fin, but a high-efficiency heat dissipation structure manufactured by aluminum alloy extrusion molding after topology optimization through coupled simulation of computational fluid dynamics and heat transfer.

[0088] Fin height =8mm, fin base thickness =1.2mm, the fin top is thinned by 0.5mm to facilitate heat transfer to the ends, fin spacing =1.5mm;

[0089] The fins adopt a nonlinear wavy profile and are arranged radially in space. The hot air rising between the fins will produce a chimney effect. The radial arrangement follows the natural development trajectory of the hot plume, while the wavy profile can periodically disturb the flow field and delay the thickening of the boundary layer.

[0090] The heat dissipation capacity of this unit is determined by the integral form of Newton's law of cooling:

[0091] ;

[0092] in, For total heat dissipation, For total surface area, For the average convective heat transfer coefficient, Fin efficiency is a key indicator for evaluating fin performance, and its calculation formula is:

[0093] ,in ;

[0094] here, It is the circumference of the fin cross section. It is the cross-sectional area of ​​the fin. It refers to the thermal conductivity of the fin material; optimized fin profiles (such as thinning the top) aim to improve... Parameters, thus A value close to 1 means that the surface temperature of the fins is closer to the base temperature, resulting in higher overall heat dissipation efficiency.

[0095] The passive heat transfer enhancement unit is a microchannel structure set on the surface of the fins to disturb the airflow and improve the convective heat transfer coefficient.

[0096] This unit is a V-shaped microchannel array with varying depth formed by precision machining on the surface of the aforementioned high-density toothed fin. The channels are located on both sides of the fin, and the channel width w gradually changes from 0.5mm at the fin root to 0.2mm at the fin tip, while the depth d is uniformly 0.4mm.

[0097] As airflow moves upwards, the V-shaped groove's ridges periodically induce minute flow separations, leading to reattachment within the downstream trough. This process effectively breaks up and resets the stable laminar boundary layer, causing it to re-evolve from a thin boundary layer in each cycle. According to boundary layer theory, the local convective heat transfer coefficient... With boundary layer thickness Inversely proportional ( ),and Increased as the process evolves ( Microchannels, by periodically resetting the boundary layer, enable the average... This significantly reduces the average convective heat transfer coefficient, thereby substantially increasing it. ;

[0098] The relationship between this enhanced heat transfer mechanism and fluid friction can be quantitatively described using the Colburn Analogy:

[0099] ;

[0100] in, It is the Stanton number ( ), characterizing heat transfer intensity; It is the Prandtl number, approximately 0.7 for air; It is the coefficient of friction;

[0101] The microchannel structure increases the friction coefficient by increasing the wall shear stress. According to this analogy, the Stanton number The convective heat transfer coefficient will also inevitably be improved.

[0102] The surface of the high-density toothed fin unit is coated with an oxide layer;

[0103] After extrusion molding, the high-density toothed fin unit undergoes hard anodizing treatment, resulting in a dense oxide layer with a thickness of 25μm and rich in alumina on the surface.

[0104] The anodic oxide layer has a high thermal emissivity. The value can reach 0.85, which allows the radiator to dissipate heat through both convection and radiation. The amount of heat dissipated by radiation is determined by the Stefan-Boltzmann law:

[0105] ;

[0106] in, It is the Stefan-Boltzmann constant (5.67 × 10⁻) 8 W / m²K 4 At higher operating temperatures (such as 70-85℃), the proportion of radiative heat dissipation in the total heat dissipation cannot be ignored. This design achieves the synergy of convection and radiation.

[0107] The hard oxide layer (microhardness > HV500) greatly enhances the fins' resistance to corrosion and impact from gravel, ensuring that the heat dissipation performance will not be reduced due to various surface degradations (such as corrosion, wear, and contamination) during a lifespan of up to 10 years / 200,000 kilometers in automotive environments.

[0108] The sealing and protection module includes a compression-compensated sealing unit and a thermal expansion compensation unit;

[0109] The compression compensation sealing unit uses an elastomer sealing ring to achieve sealing by a preset compression amount. The compression compensation sealing unit includes a sealing ring and a sealing groove structure. Its sealing principle is based on the elastic deformation behavior of the sealing material.

[0110] The O-ring is made of fluororubber (FKM) as the main sealing element. Its hardness is Shore A70-80, which has good resistance to high and low temperatures and chemical stability. The sealing groove is a rectangular groove. Its key innovation is that its width is slightly larger than the diameter of the sealing ring wire, and it adopts a groove bottom design with rounded corners.

[0111] When the sealing ring is compressed, the resulting contact stress This is crucial for ensuring a tight seal; the stress can be described by the Mooney-Rivlin hyperelastic model, which defines the strain energy function W:

[0112] ;

[0113] in, and It is the Mooney-Rivlin constant of the material. and They are the first and second invariants of the isochoric deformation tensor. It is the volume ratio, It is a parameter related to the compressibility of materials;

[0114] Finite element analysis can accurately simulate the contact stress generated by the sealing ring under a preset compression rate of 20-30%. It must always be greater than the maximum possible pressure difference between the inside and outside of the system. (The test pressure corresponding to IP6K9K waterproof rating), that is: The wide groove and rounded bottom design ensures that the sealing ring can generate a uniform stress distribution when compressed, and reserves space for it to undergo moderate lateral flow under pressure, forming a wider and more stable sealing band, avoiding stress concentration and premature failure caused by sharp corners.

[0115] The thermal expansion compensation unit uses a flexible thermally conductive pad, and its thermal expansion is determined by the formula... Calculation, where The coefficient of thermal expansion is For the initial length, To absorb thermal displacement between assemblies in response to temperature changes, the thermal expansion compensation unit includes a flexible thermally conductive pad and an adhesive layer.

[0116] The flexible thermal pad uses a functional composite material with silicone as the matrix and filled with 40% by volume boron nitride (BN) sheets. Its thickness... The thickness is 1.0 mm, and the adhesive layer is a low-modulus, high-elongation silicone-based thermally conductive adhesive;

[0117] The core function of this unit is to absorb thermal displacement caused by the mismatch of the coefficients of thermal expansion (CTE) of different materials. ;

[0118] First, the radar housing (e.g., plastic, CTE is...) ≈60×10 -6 / ℃) and heat sink (aluminum alloy, CTE is ≈23×10 -6 / ℃) in temperature change The relative displacement difference is:

[0119] ;

[0120] The thermal expansion of the flexible thermal pad itself The linear thermal expansion formula gives:

[0121] ;

[0122] The choice of thermal pad material is based on its excellent mechanical compliance and extremely low elastic modulus. With high elongation at break, when displacement difference occurs due to CTE mismatch. At this time, this displacement is applied as an external forced strain to the soft thermal pad. Due to its extremely low modulus, the thermal pad can accommodate this displacement by undergoing large, recoverable shear and compressive elastic deformation, rather than generating huge shear stress at the interface. The interfacial shear stress is estimated by the following formula:

[0123] ;

[0124] in It is the shear modulus of the thermal pad. Its thickness is due to the silicone matrix. Extremely low, even with large deformation, the resulting It is also far lower than the bonding strength of the adhesive layer, thus ensuring that the interface does not delaminate or crack;

[0125] At the same time, this unit must maintain good thermal conductivity. Its equivalent thermal resistance... for:

[0126] By using high-fill BN, The efficiency was increased to over 3.0 W / (m·K), ensuring that thermal stress compensation was achieved without becoming a bottleneck in the system's heat dissipation path.

[0127] Structural reinforcement units enhance the overall structural stiffness and natural frequency by adding supporting structures or strengthening materials, enabling the structure to meet preset fatigue life requirements in mechanical vibration environments while maintaining heat dissipation performance.

[0128] The main body of this unit is a high-strength aluminum alloy (such as 7075-T6) frame integrally formed with the heat sink body or connected by high thermal conductivity brazing. This frame undergoes multiphysics topology optimization using the finite element method (FEA), and the natural frequency is calculated using the following formula: ;

[0129] Maximize the overall structural stiffness (K) to increase the natural frequency; maximize the average thermal conductivity along the heat dissipation path (K). To minimize thermal resistance; to minimize overall mass (M) to meet lightweight requirements;

[0130] First-order natural frequency ≥500Hz; Equivalent stress in key areas (such as fin roots and module connections) ≤ Material fatigue limit 50%; Equivalent thermal resistance from the heat sink substrate to the environment ≤ target value;

[0131] The optimization results generated a non-uniform rib structure: in non-critical heat transfer areas of the radiator body (such as the central area of ​​the fin array and the sidewalls of the module), a series of internal reinforcing ribs and arched support structures were generated. These structures constitute an efficient space truss system that evenly distributes concentrated stress throughout the shell.

[0132] The core function of structural reinforcement units is to raise the natural frequency of the system above the range of external excitation frequencies. For a multi-degree-of-freedom system, its natural frequency... The relationship between stiffness K and mass M is determined by the eigenvalues ​​of the following equation:

[0133] ;

[0134] in, It is angular frequency. It is a quality matrix. It is the stiffness matrix. It is the mode shape vector, which greatly improves the overall stiffness matrix by strengthening the frame. The key element in this is the lowest-order natural frequency (first-order mode) of the system. Designed for frequencies above 500Hz;

[0135] According to the vibration transmissibility theory, when the excitation frequency... With the system's natural frequency satisfy At that time, the system was in the vibration isolation zone; the common vibration excitation frequency in automobiles is usually between 10-2000Hz, but the main energy is concentrated in the low frequency (<500Hz). Designed for frequencies above 500Hz, this ensures that the system's dynamic response is significantly suppressed for the vast majority of major excitations, and the vibration acceleration transmissibility is minimized. This achieves passive vibration isolation.

[0136] To ensure compliance with 10 in a vibration environment with 20g acceleration. 7 For the fatigue life of the next cycle, this implementation adopts a scheme based on the stress-life (SN) curve and Miner's linear cumulative damage rule:

[0137] By optimizing the topology and strengthening the structure, the alternating stress amplitude in the stress concentration region under vibration load is reduced. Controlled within the material's fatigue limit The following conditions must be met for the high-cycle fatigue behavior of aluminum alloys:

[0138] ;

[0139] in This represents the number of failure cycles. and It is a material constant, when At that time, theoretically This solution strengthens the key points. far below This lays the foundation for achieving an ultra-long fatigue life;

[0140] For those containing multiple frequency components For random vibrations, the Miner's rule is used to calculate the cumulative damage:

[0141] ;

[0142] in, At stress level The actual number of loops, This refers to the number of cycles that lead to failure at this stress level; the design objective is to minimize the total damage. Thus, under the preset vibration test spectrum and full life cycle load spectrum, the system is far from reaching fatigue failure.

[0143] The high-efficiency heat dissipation system for automotive high-frequency millimeter-wave radar operates as a multi-module, sequential, and highly efficient thermal management process.

[0144] First, the thermal module, as the starting point of the system, is in direct contact with the radar chip. It uses the internal high thermal conductivity composite material and vertically interconnected metal vias to act as a high-speed heat flow channel, which quickly captures and guides the core heat generated by the chip during operation from the heat source area, laying the foundation for subsequent processing.

[0145] The heat that is drawn out then enters the thermal storage module. This module acts as a thermal energy stabilizer for the system. The phase change material inside the module undergoes a phase change after absorbing heat, storing a large amount of thermal energy. This process can effectively smooth out peaks and valleys, buffer the instantaneous high heat load generated by the intermittent operation of the radar, and prevent the temperature from soaring. At the same time, the heat homogenization structure inside the module promotes the rapid and uniform diffusion of heat inside, minimizing regional temperature differences and preventing local overheating.

[0146] After being buffered and homogenized, the heat is finally dissipated by the convection cooling module. This module, through its large-surface-area passive fin structure, makes full contact with the surrounding air and uses the natural convection effect of the air to continuously carry away and release the heat accumulated on the surface of the heat sink into the external environment, completing the last step of the heat dissipation cycle, thereby providing a continuously cooled working environment for the radar chip.

[0147] Throughout the entire heat dissipation process, the sealing and protection module provides crucial environmental protection for the system. It effectively resists the intrusion of external moisture and dust through its elastic sealing structure, while using flexible compensation materials to absorb the internal stress caused by the inconsistent thermal expansion and contraction of different components due to alternating hot and cold cycles. This ensures the sealing integrity and connection reliability of all the above thermal management functions during long-term operation in complex vehicle environments.

[0148] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0149] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-efficiency heat dissipation system for automotive high-frequency millimeter-wave radar, characterized in that, The system includes a heat conduction module, a heat storage module, a convection heat dissipation module, and a sealing and protection module; The heat-conducting module rapidly removes heat from the chip's heat source through a highly thermally conductive material and a metal interconnect structure, a process that follows Fourier's law. The thermal storage module utilizes phase change materials to absorb and store a large amount of latent heat during the phase transition, so as to buffer instantaneous high heat loads, and makes the internal temperature field of the system uniform through a heat equalization structure. The convection heat dissipation module increases the contact area with the air through a passive heat dissipation structure, and uses natural air convection to continuously dissipate heat into the environment. The heat flow rate of this process is determined by Newton's law of cooling. The sealing and protection module uses an elastic sealing material to achieve static sealing under compression, and uses a flexible thermally conductive material to compensate for the stress caused by the mismatch of thermal expansion coefficients between different components.

2. The high-efficiency heat dissipation system for automotive high-frequency millimeter-wave radar according to claim 1, characterized in that: The thermally conductive module includes a high thermal conductivity composite substrate unit and a metallized thermal connection unit. The high thermal conductivity composite substrate unit is composed of a metal core layer and a carbon-based high thermal conductivity layer. The metallized thermal connection unit includes an array of vias penetrating the substrate, and its thermal conductivity is described by the Fourier law: ,in For heat flux density, The thermal conductivity of the material For temperature gradient.

3. The high-efficiency heat dissipation system for automotive high-frequency millimeter-wave radar according to claim 2, characterized in that: The carbon-based high thermal conductivity layer of the high thermal conductivity composite substrate unit is a graphene layer with high orientation.

4. The high-efficiency heat dissipation system for automotive high-frequency millimeter-wave radar according to claim 1, characterized in that: The thermal storage module includes a phase change thermal storage unit and a heat-spreading fin unit. The phase change thermal storage unit is filled with an organic-inorganic composite phase change material, and its total thermal storage capacity is given by the formula. Description, in which Total latent heat, For the quality of phase change materials, Latent heat of phase transition; The heat exchange fin unit extends into the phase change material to increase the heat exchange area.

5. The high-efficiency heat dissipation system for automotive high-frequency millimeter-wave radar according to claim 4, characterized in that: The organic-inorganic composite phase change material contains dispersed nano-ceramic particles, and the surface of the heat-dampening fin unit is treated with micro-nano structures to enhance its wettability with the phase change material.

6. The high-efficiency heat dissipation system for automotive high-frequency millimeter-wave radar according to claim 1, characterized in that: The convection heat dissipation module includes a high-density toothed fin unit and a passive heat exchange enhancement unit. The high-density toothed fin unit enhances heat dissipation by increasing the heat dissipation surface area. Its heat dissipation efficiency is proportional to the surface area and follows Newton's law of cooling. ,in The convective heat transfer coefficient is... The surface temperature for heat dissipation. Ambient temperature; The passive heat transfer enhancement unit is a microchannel structure disposed on the fin surface, which disturbs airflow to improve the convective heat transfer coefficient. .

7. The high-efficiency heat dissipation system for automotive high-frequency millimeter-wave radar according to claim 6, characterized in that: The surface of the high-density toothed fin unit is coated with an oxide layer; The oxide layer is formed by anodizing the surface of aluminum alloy after extrusion molding.

8. The high-efficiency heat dissipation system for automotive high-frequency millimeter-wave radar according to claim 1, characterized in that: The sealing protection module includes a compression compensation sealing unit and a thermal expansion compensation unit; The compression compensation sealing unit uses an elastomer sealing ring, which achieves sealing through a preset compression amount; The thermal expansion compensation unit uses a flexible thermally conductive pad, and its thermal expansion is calculated by the formula... Calculation, where The coefficient of thermal expansion is For the initial length, This represents the temperature change, absorbing the thermal displacement between assemblies.

9. The high-efficiency heat dissipation system for automotive high-frequency millimeter-wave radar according to claim 8, characterized in that: The compression compensation sealing unit includes a sealing ring and a sealing groove structure, and its sealing principle is based on the elastic deformation behavior of the sealing material; the thermal expansion compensation unit includes a flexible thermally conductive pad and an adhesive layer.

10. The high-efficiency heat dissipation system for automotive high-frequency millimeter-wave radar according to claim 1, characterized in that: The structural reinforcement unit enhances the overall structural stiffness and natural frequency by adding supporting structures or material reinforcement, enabling it to meet preset fatigue life requirements in mechanical vibration environments while maintaining heat dissipation performance.

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