Subway train laser headlamp and optimization method thereof

Abstract

The invention relates to the technical field of laser illumination, in particular to a subway train laser headlamp and an optimization method thereof, and the optimization method comprises the following steps: radiating the laser headlamp through a convective heat transfer strengthening technology; the materials of the headlamp main body and the headlamp mounting ring are optimized through COMSOL thermal simulation; and the RGB laser pumping sources are compounded to generate white light through photoelectric conversion efficiency optimization. The method has the advantages that the subway train headlamp is subjected to strong heat dissipation through active and passive dual heat dissipation formed by convective heat exchange, the material of the subway train laser headlamp is optimized, the heat dissipation performance of the subway train laser headlamp is better, the mode that the red light pumping source, the green light pumping source and the blue light pumping source are compounded to generate white light is optimized according to the calculation result of the photoelectric conversion efficiency, and the heat dissipation efficiency of the subway train laser headlamp is improved. Therefore, the color development and the photoelectric conversion efficiency of laser illumination reach the optimal state, and the purpose of obtaining better illumination with lower energy consumption is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of laser lighting, in particular to a subway train laser headlamp and an optimization method thereof. Background Art

[0002] The lights of subway trains are an indispensable and important part in the driving process. The headlights of subway trains can improve the line of sight and expand the observation field. Most of the existing subway train headlights use xenon lamps, halogen lamps or LED lamps for lighting, which have problems such as low luminous efficiency and short life. Laser headlight technology has the advantages of high brightness, long lighting distance, and low energy consumption, so it has the potential to be used in high-speed train headlights. However, at present, with the pursuit of high power, the heat dissipation of devices has become more difficult. Because semiconductor lasers can generate very high peak power, their electro-optical conversion efficiency is 40% to 50%, that is, 50% to 60% of the input electrical energy can be converted into heat energy, and the heat flux generated at the place where the core is welded is about 1kW / cm 2 This heat load is the key factor limiting the normal operation of the laser. Therefore, if the heat dissipation problem is not solved well, it will cause the temperature of the laser to rise rapidly, thus causing the optical catastrophe of the laser. Summary of the invention

[0003] In view of the above problems or problems existing in the prior art, the present invention is proposed.

[0004] Therefore, the object of the present invention is to provide a method for optimizing subway train laser headlights, which can enhance the heat dissipation capability and improve the lighting intensity under the condition of lower energy consumption.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for optimizing laser headlights for subway trains, comprising dissipating heat from the laser headlights by means of convection heat transfer enhancement technology;

[0006] Optimize the materials of the headlamp body and headlamp mounting ring through COMSOL thermal simulation;

[0007] White light is generated by compounding RGB red, green and blue laser pump sources through optimizing photoelectric conversion efficiency.

[0008] As a preferred solution of the subway train laser headlamp optimization method of the present invention, the convective heat transfer enhancement technology includes two methods: passive technology and active technology. The passive technology adopts an active heat dissipation method, and the active technology adopts a passive heat dissipation method.

[0009] The active and passive combination method is adopted to dissipate heat through thermal convection heat transfer, and the formula is as follows:

[0010] Φ=hA(t w -t ∞)

[0011] q=Φ / A=h(t w -t ∞ )

[0012] Among them, t w Indicates the solid wall temperature in K; t ∞ represents the fluid temperature in K; h is the surface heat transfer coefficient in W / (m 2 K), which characterizes the strength of the convective heat transfer process;

[0013] Among them, the heat transfer coefficient h and the convection thermal resistance R h Inversely proportional, that is, the convection thermal resistance R h and unit convection thermal resistance r h The expression is as follows:

[0014] R h =1 / (hA)

[0015] r h =1 / h

[0016] Where Rh is the convection thermal resistance, rh is the unit convection thermal resistance, and A is the parameter.

[0017] As a preferred solution of the subway train laser headlamp optimization method of the present invention, wherein: the COMSOL thermal simulation, when performing thermal simulation, COMSOL uses a control equation to describe the physical phenomenon, and the equation is as follows:

[0018]

[0019] Where ρ is the density, c is the specific heat, T is the temperature, k is the thermal conductivity, Q is the volume heat source, and and denote the divergence and gradient operators respectively;

[0020] Newton's cooling equation can be applied to the model as a boundary condition or initial condition in COMSOL to simulate the convective heat transfer process. The equation is expressed as:

[0021] q=h(T S -T ∞ )

[0022] Where q is the heat flow, h is the convective heat transfer coefficient, T S is the solid surface temperature, T ∞ is the far-field temperature of the fluid.

[0023] As a preferred solution of the subway train laser headlamp optimization method of the present invention, the COMSOL thermal simulation performs a temperature range simulation calculation of thermal convection heat transfer, and forms a COMSOL thermal simulation temperature distribution diagram with the simulation values, and obtains the highest temperatures of three heat dissipation materials, 304 stainless steel, iron, and aluminum alloy, according to the COMSOL thermal simulation, and compares them with the temperature range of thermal convection heat transfer, and selects aluminum alloy as the material of the headlamp body and the headlamp mounting ring.

[0024] As a preferred solution of the subway train laser headlamp optimization method of the present invention, the RGB red, green and blue laser pump sources are compounded to generate white light, and the CIE color matching function is used to perform a linear combination of the three primary colors to convert any color into an XYZ color space, where X, Y and Z represent three imaginary primary colors respectively. The specific formula is as follows:

[0025] R′=X·Rr+Y·Rg+Z·Rb

[0026] G′=X·Gr+Y·Gg+Z·Gb

[0027] B′=X·Rr+Y·Bg+Z·Bb

[0028] Among them, R, G, B are the synthesized red, green, and blue components, Rr, Gg, Bb are the original red, green, and blue components, and X, Y, and Z are the color matching functions of the CIE standard observer;

[0029] When synthesizing white light, it is necessary to ensure that the power or intensity of the red, green, and blue lasers are mixed in a certain ratio to produce white light perceived by the human eye. This usually involves weighted summation of the power of each color laser:

[0030] P total =P r +P g +P b

[0031] Among them, P total is the total power of the combined light, P r , P g , P b are the powers of red, green and blue lasers respectively;

[0032] The contribution of each color to the perceived brightness is determined using the CIE color matching functions, which correspond to red, green, and blue with r(λ), g(λ), and b(λ), respectively, and the spectral power distribution of each color laser is Pr(λ), Pg(λ), and Pb(λ), where λ is the wavelength;

[0033] Integrate the weighted spectral power distribution to get the contribution of each color laser to the total brightness:

[0034] P′ r =∫P r (λ)·r(λ)dλ

[0035] P g =∫P g (λ)·g(λ)dλ

[0036] P′ b =∫P b (λ)·b(λ)dλ

[0037] According to the contribution of each color laser to the total brightness, calculate the required power P of each color laser r , P g , P b :

[0038]

[0039] where ω r ,ω g ,ω b are weighting factors for each color of laser light, and they can be adjusted according to the desired white light properties.

[0040] As a preferred solution of the subway train laser headlamp optimization method of the present invention, the photoelectric conversion efficiency is a measure of the ability of the light source to convert electrical energy into light energy, that is, the ratio of the output light energy to the input electrical energy, and its formula is as follows:

[0041]

[0042] Among them, P out is the optical power output by the light source, P in is the optical power input from the light source;

[0043] The photoelectric conversion efficiency includes pump efficiency, quantum efficiency of fluorescent materials, transmission efficiency of optical systems, and total light conversion efficiency;

[0044] Among them, the pump efficiency includes calculating the photoelectric conversion efficiency of the pump source, that is, the efficiency of converting electrical energy into laser, and the formula is as follows:

[0045]

[0046] Among them, Plaser_out is the laser power output by the laser diode, and Pelectric_in is the electrical power consumed by the laser diode;

[0047] The quantum efficiency of fluorescent materials includes calculating the efficiency of fluorescent materials absorbing pump light and emitting light. The formula is as follows:

[0048]

[0049] Among them, P fluorescence_out is the light power emitted by the fluorescent material, P laser_in is the laser power absorbed by the fluorescent material;

[0050] The transmission efficiency of an optical system involves calculating the transmission efficiency of light in the optical system from the light source to the final output, including any reflection, absorption or scattering losses. The formula is as follows:

[0051]

[0052] Among them, P optical_out is the optical power output by the optical system, P optical_in is the optical power entering the optical system;

[0053] The total light conversion efficiency involves multiplying the above efficiencies to obtain the light-to-light conversion efficiency of the entire system, as shown below:

[0054]

[0055] Among them, P out is the final optical power output after passing through the entire system, P in is the total optical power input by the light source.

[0056] In order to solve the above technical problems, the present invention also provides the following technical solutions: A subway train laser headlamp comprises a laser emitting unit, a fixing component, and a lighting component arranged inside the fixing component;

[0057] The heat dissipation unit comprises a heat dissipation component arranged on one side of the fixing component.

[0058] As a preferred solution of the subway train laser headlight optimization method of the present invention, the fixing assembly includes a base plate, a fixing ring arranged on the upper side of the base plate, and a mounting ring arranged on one side of the base plate.

[0059] As a preferred solution of the rail wear measuring device of the present invention, the lighting assembly includes a headlamp body arranged on one side of the mounting ring, a lighting laser source arranged on the inner side of the fixing ring, a focusing lens arranged on the upper side of the lighting laser source, and a circuit board arranged on the lower side of the base plate.

[0060] As a preferred solution of the rail wear measuring device of the present invention, the heat dissipation component includes a fan arranged on the inner side of the headlamp body, and a heat dissipation gasket arranged on the inner side of the fixing ring.

[0061] Beneficial effects of the present invention: The present invention uses active and passive dual heat dissipation formed by convection heat transfer to strongly dissipate the heat of subway train headlights, and optimizes the material of subway train laser headlights to make them have better heat dissipation performance. The red, green and blue light pump source composite method of generating white light is optimized through the calculation result of photoelectric conversion efficiency, so that the color rendering and photoelectric conversion efficiency of laser lighting are both in the optimal state, achieving the goal of obtaining better lighting with lower energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0063] Figure 1 Temperature distribution diagram of active and passive heat dissipation of COMSOL thermal simulation for the optimization method of subway train laser headlights.

[0064] Figure 2 Temperature distribution diagram of three materials in COMSOL thermal simulation for the optimization method of subway train laser headlights.

[0065] Figure 3 This is a schematic diagram of the overall structure of the subway train laser headlight.

[0066] Figure 4 Schematic diagram of the overall structure explosion of the laser headlight of a subway train. DETAILED DESCRIPTION

[0067] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0068] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0069] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0070] Example 1

[0071] Reference Figure 1 and Figure 2 , which is the first embodiment of the present invention, provides a method for optimizing subway train laser headlights, which can enhance heat dissipation capabilities and improve lighting intensity under conditions of lower energy consumption.

[0072] Specifically, the heat dissipation of the laser headlamp is carried out by using the convection heat transfer enhancement technology;

[0073] Optimize the materials of the headlamp body and headlamp mounting ring through COMSOL thermal simulation;

[0074] White light is generated by compounding RGB red, green and blue laser pump sources through optimizing photoelectric conversion efficiency.

[0075] Furthermore, the convection heat transfer enhancement technology includes two methods: passive technology and active technology. Passive technology uses active heat dissipation, while active technology uses passive heat dissipation.

[0076] The active and passive combination method is adopted to dissipate heat through thermal convection heat transfer, and the formula is as follows:

[0077] Φ=hA(t w -t ∞ )

[0078] q=Φ / A=h(t w -t ∞ )

[0079] Among them, t w Indicates the solid wall temperature in K; t ∞ represents the fluid temperature in K; h is the surface heat transfer coefficient in W / (m 2 K), which characterizes the strength of the convective heat transfer process;

[0080] Among them, the heat transfer coefficient h and the convection thermal resistance R h Inversely proportional, that is, the convection thermal resistance R h and unit convection thermal resistance r h The expression is as follows:

[0081] R h =1 / (hA)

[0082] r h =1 / h

[0083] Among them, R h is the convection thermal resistance, r h is the unit convection thermal resistance, and A is the parameter.

[0084] It should be noted that in practical applications, the h value cannot be directly obtained. Instead, the calculation relationship of the headlamp surface heat transfer coefficient under different conditions is obtained through theoretical analysis or experimental methods, that is, the following laminar flow convection heat transfer differential equations are satisfied:

[0085] Continuity equation:

[0086]

[0087] Momentum differential equation Navier-Stokes equations:

[0088]

[0089] Energy differential equation:

[0090]

[0091] Convective heat transfer equation:

[0092]

[0093] In the above equations, u and v are the flow velocities of the fluid in the x and y directions, respectively, in m / s; ρ, c p , λ are density, specific heat capacity and thermal conductivity of the fluid respectively; μ is the viscosity of the fluid, in pas; is the fluid heat flow; F is the volume force acting on the solid, unit is N; p is the pressure, unit is N; τ is the time; n is the coordinate along the wall normal direction.

[0094] By solving the above differential equations using the boundary layer integral method and similarity theory, the average convective heat transfer coefficient between the fluid and the solid wall can be obtained. For the forced convective heat transfer form, the boundary layer integral equations are established as follows:

[0095] Momentum integral equation:

[0096]

[0097] Boundary layer energy integral equation:

[0098]

[0099] Solving the boundary layer integral equation gives the following results:

[0100] Velocity boundary layer thickness δ:

[0101]

[0102] Thermal boundary layer thickness δ t :

[0103]

[0104] Local surface heat transfer coefficient h:

[0105]

[0106] Local wall shear stress Nu:

[0107]

[0108] The Reynolds number Re is a dimensionless number that characterizes the flow of a fluid, and its expression is:

[0109] Re c =u ∞ X c / v

[0110] Among them, when the Reynolds number is greater than 5×10 5 When the flow changes from laminar flow to turbulent flow.

[0111] Qualitative temperature t used to calculate physical properties m is the average temperature of the boundary layer:

[0112] t m =(t ∞ +t w ) / 2

[0113] The final average surface heat transfer coefficient h is solved by the formula:

[0114]

[0115] Among them, l is the characteristic length of the solid surface through which the fluid flows, and the Prandtl number Pr is the dimensionless parameter of the object.

[0116] For natural convection, h can also be solved by other empirical equations. To this end, some dimensionless numbers are first defined.

[0117] The Nusselt number Nu represents the ratio of the thermal conductivity resistance to the convective heat transfer resistance in the bottom layer of the fluid laminar flow:

[0118]

[0119] The Prandtl number Pr represents the relationship between the temperature boundary layer and the flow boundary layer:

[0120]

[0121] The Grashof number Gr represents the ratio of natural convection buoyancy to viscous force. When the Grashof number Gr>10 9 When , the natural convection boundary layer changes from laminar flow to turbulent flow, and its expression is:

[0122]

[0123] Among them, L is the characteristic scale; β is the volume change coefficient; g is the gravitational acceleration; ΔT is the temperature difference; and v is the dynamic viscosity coefficient.

[0124] The following relationship exists between the three dimensionless numbers:

[0125] Nu=C(G r ·P r ) m

[0126] C and m are constant coefficients. After determining the qualitative temperature and related environmental conditions, they can be obtained by looking up a table or experiment. Combined with the formula, the convection heat transfer coefficient h between the natural convection fluid and the solid surface can be calculated:

[0127]

[0128] By consulting relevant information, we know that the convection heat transfer coefficient of air is 0-25, and the forced convection heat transfer coefficient of air is 20-300. Theoretically, forced convection of air (active heat dissipation) can greatly improve the heat dissipation efficiency.

[0129] Furthermore, COMSOL thermal simulation, when performing thermal simulation, COMSOL uses the control equation to describe the physical phenomenon, and the equation is as follows:

[0130]

[0131] Where ρ is the density, c is the specific heat, T is the temperature, k is the thermal conductivity, Q is the volume heat source, and and denote the divergence and gradient operators respectively;

[0132] Newton's cooling equation can be applied to the model as a boundary condition or initial condition in COMSOL to simulate the convective heat transfer process. The equation is expressed as:

[0133] q=h(T S -T ∞ )

[0134] Where q is the heat flow, h is the convective heat transfer coefficient, T S is the solid surface temperature, T ∞ is the far-field temperature of the fluid.

[0135] In addition, when a solid is deformed, thermoelastic effects need to be considered. This involves the thermal expansion coefficient of the material, which is temperature-dependent and can affect the mechanical behavior of the material. In COMSOL, this effect can be modeled by coupling the Solid Mechanics interface to the Heat Transfer interface. The coupling terms include heat sources due to thermal expansion, as well as the temperature-dependent elastic matrix and thermal strain tensor.

[0136] like Figure 1 As shown in the figure, it is the temperature distribution diagram of COMSOL thermal simulation. The long bar on the right side of the figure represents the temperature range. The value above the long bar is the highest temperature, and the value below the long bar is the lowest temperature. By observing the temperature distribution diagram of passive heat dissipation ( Figure 1 (a) shows that when passive cooling is used, the maximum temperature of the model reaches 79.6℃ and the minimum temperature reaches 66.3℃; while when active cooling is used (such as Figure 1 (b)), the maximum temperature of the model was reduced to 52.7℃, and the minimum temperature was reduced to 40℃. The active and passive methods were combined to dissipate heat for the subway train laser headlights, and the heat dissipation method was selected according to the different temperatures generated by the headlights in different usage states.

[0137] Furthermore, COMSOL thermal simulation is used to simulate the temperature range of thermal convection heat transfer, and the simulation values ​​are used to form a COMSOL thermal simulation temperature distribution diagram. The maximum temperatures of three heat dissipation materials, 304 stainless steel, iron, and aluminum alloy, are obtained based on COMSOL thermal simulation, and compared with the temperature range of thermal convection heat transfer, and aluminum alloy is selected as the material for the headlamp body and the headlamp mounting ring.

[0138] It should be noted that the thermal conductivity of aluminum alloy is 201, the thermal conductivity of iron is 46.52, and the thermal conductivity of 304 stainless steel is 15. It can be seen that aluminum alloy has a higher thermal conductivity than iron and 304 stainless steel. Therefore, aluminum alloy as the material of the headlamp body and the headlamp mounting ring can greatly improve the heat dissipation efficiency and meet the heat dissipation requirements of the headlamp.

[0139] COMSOL is used to perform thermal simulation on iron, steel and aluminum alloy as heat dissipation materials. Figure 2 As shown in the figure, it is the temperature distribution diagram of the heat dissipation material of COMSOL thermal simulation. The long bar on the right side of the figure represents its temperature range. Different colors represent different temperatures. The value above the long bar is the highest temperature, and the value below the long bar is the lowest temperature. By observing the temperature distribution diagram, it can be seen that Figure 2 As shown in (a), when 304 stainless steel is used as the heat dissipation material, the maximum temperature of the model reaches 137°C; Figure 2 As shown in (b), when iron is used as the heat dissipation material, the maximum temperature of the model reaches 98.2℃; Figure 2As shown in (c), when aluminum alloy is used as the heat dissipation material, the maximum temperature of the model is reduced to 79.6℃, that is, using aluminum alloy as the heat dissipation material can greatly increase the heat dissipation efficiency compared with 304 stainless steel and iron.

[0140] Furthermore, the RGB red, green and blue laser pump sources are combined to produce white light, and the CIE color matching function is used to perform a linear combination of the three primary colors to convert any color into the XYZ color space, where X, Y and Z represent three imaginary primary colors, respectively. The specific formula is as follows:

[0141] R′=X·Rr+Y·Rg+Z·Rb

[0142] G′=X·Gr+Y·Gg+Z·Gb

[0143] B′=X·Rr+Y·Bg+Z·Bb

[0144] Among them, R, G, B are the synthesized red, green, and blue components, Rr, Gg, Bb are the original red, green, and blue components, and X, Y, and Z are the color matching functions of the CIE standard observer;

[0145] When synthesizing white light, it is necessary to ensure that the power or intensity of the red, green, and blue lasers are mixed in a certain ratio to produce white light perceived by the human eye. This usually involves weighted summation of the power of each color laser:

[0146] P total =P r +P g +P b

[0147] Among them, P total is the total power of the combined light, P r , P g , P b are the powers of red, green and blue lasers respectively;

[0148] The contribution of each color to the perceived brightness is determined using the CIE color matching functions, which correspond to red, green, and blue with r(λ), g(λ), and b(λ), respectively, and the spectral power distribution of each color laser is Pr(λ), Pg(λ), and Pb(λ), where λ is the wavelength;

[0149] Integrate the weighted spectral power distribution to get the contribution of each color laser to the total brightness:

[0150] P′ r =∫P r (λ)·r(λ)dλ

[0151] P′ g =∫P g(λ)·g(λ)dλ

[0152] P′ b =∫P b (λ)·b(λ)dλ

[0153] According to the contribution of each color laser to the total brightness, calculate the required power P of each color laser r , P g , P b :

[0154]

[0155] where ω r ,ω g ,ω b are weighting factors for each color of laser light, and they can be adjusted according to the desired white light properties.

[0156] Furthermore, the photoelectric conversion efficiency is a measure of the ability of a light source to convert electrical energy into light energy, that is, the ratio of the output light energy to the input electrical energy. The formula is as follows:

[0157]

[0158] Among them, P out is the optical power output by the light source, P in is the optical power input from the light source;

[0159] Photoelectric conversion efficiency includes pump efficiency, quantum efficiency of fluorescent materials, transmission efficiency of optical systems, and total light conversion efficiency;

[0160] Among them, the pump efficiency includes calculating the photoelectric conversion efficiency of the pump source, that is, the efficiency of converting electrical energy into laser, and the formula is as follows:

[0161]

[0162] Among them, Plaser_out is the laser power output by the laser diode, and Pelectric_in is the electrical power consumed by the laser diode;

[0163] The quantum efficiency of fluorescent materials includes calculating the efficiency of fluorescent materials absorbing pump light and emitting light. The formula is as follows:

[0164]

[0165] Among them, P fluorescence_out is the light power emitted by the fluorescent material, P laser_in is the laser power absorbed by the fluorescent material;

[0166] The transmission efficiency of an optical system involves calculating the transmission efficiency of light in the optical system from the light source to the final output, including any reflection, absorption or scattering losses. The formula is as follows:

[0167]

[0168] Among them, P optical_out is the optical power output by the optical system, P optical_in is the optical power entering the optical system;

[0169] The total light conversion efficiency involves multiplying the above efficiencies to obtain the light-to-light conversion efficiency of the entire system, as shown below:

[0170]

[0171] Among them, P out is the final optical power output after passing through the entire system, P in is the total optical power input by the light source.

[0172] Finally, the following table shows:

[0173]

[0174] The photoelectric conversion efficiency of white light produced by direct recombination of RGB red, green and blue laser pump sources can reach 75%; while the photoelectric conversion efficiency of white light produced by near-ultraviolet laser excitation of RGB phosphors and remote excitation of yellow phosphors by blue lasers is 50% and 36.7% respectively. On the other hand, when white light is produced by direct recombination of RGB red, green and blue laser pump sources, the color rendering index can reach more than 95; when white light is produced by near-ultraviolet laser excitation of RGB phosphors, the display index is 95; and when white light is produced by remote excitation of yellow phosphors by blue lasers, the color rendering index can only reach 63-71. It can be seen that the white light produced by direct recombination of RGB red, green and blue laser pump sources has higher electro-optical conversion efficiency and color rendering index, which can not only improve lighting efficiency and quality, but also because there is no fluorescence conversion process, the photoelectric conversion efficiency is high, and the energy loss emitted by the pump source is small, which helps to improve the heat dissipation efficiency of the equipment and reduce heat accumulation.

[0175] In summary, the present invention uses active and passive dual heat dissipation formed by convective heat transfer to strongly dissipate the heat of subway train headlights, and optimizes the material of subway train laser headlights to make their heat dissipation performance better. The red, green and blue light pump sources are combined to produce white light through the calculation results of the photoelectric conversion efficiency, so that the color rendering and photoelectric conversion efficiency of laser lighting are both in the optimal state, achieving the goal of obtaining better lighting with lower energy consumption.

[0176] Example 2

[0177] Reference Figure 3 and Figure 4 , which is the second embodiment of the present invention, provides a rail wear measuring device, which can perform dual heat dissipation for subway headlights and improve lighting performance through laser lighting.

[0178] Specifically, the laser emitting unit 100 includes a fixing component 101 and an illumination component 102 disposed inside the fixing component 101;

[0179] The heat dissipation unit 200 includes a heat dissipation component 201 disposed on one side of the fixing component 101 .

[0180] Furthermore, the fixing assembly 101 includes a bottom plate 101 a , a fixing ring 101 b disposed on the upper side of the bottom plate 101 a , and a mounting ring 101 c disposed on one side of the bottom plate 101 a .

[0181] Furthermore, the lighting assembly 102 includes a headlamp body 102a arranged on one side of the mounting ring 101c, a lighting laser source 102b arranged on the inner side of the fixing ring 101b, a focusing lens 102c arranged on the upper side of the lighting laser source 102b, and a circuit board 102d arranged on the lower side of the base plate 101a.

[0182] Furthermore, the heat dissipation assembly 201 includes a fan 201a disposed inside the headlamp body 102a, and a heat dissipation gasket 201b disposed inside the fixing ring 101b.

[0183] It should be noted that the headlamp body 102a is arranged on the inner side of the mounting ring 101c and is installed at the subway train headlamp installation position through the mounting ring 101c, the base plate 101a is arranged on the inner side of the headlamp body 102a, the fixing ring 101b is fixedly connected to the base plate 101a, the heat dissipation gasket 201b is arranged between the fixing ring 101b and the lighting lamp laser source 102b, the circuit board 102d is fixedly connected to the base plate 101a, and the focusing lens 102c is fixedly connected to the fixing ring 101b.

[0184] When in use, the circuit board 102d is connected to the lighting laser source 102b through the base plate 101a, and the lighting laser source 102b is controlled to emit light. The lighting laser source 102b forms white light through the red, green and blue primary color pump sources, and the focusing is adjusted by the focusing lens 102c to adjust the color rendering of the white light and reach the maximum brightness. When the lighting laser source 102b is illuminated, the temperature of the headlamp body 102a begins to rise. When the temperature rises to a certain level, passive heat dissipation is started. When the lighting laser source 102b has been working for a long time and the temperature cannot continue to drop through passive heat dissipation, but continues to rise, active heat dissipation is started, and the fan 201a starts to rotate. Active and passive heat dissipation are carried out simultaneously to dissipate the heat of the headlamp body 102a to achieve a better heat dissipation effect.

[0185] When the lighting laser source 102b stops lighting, active and passive heat dissipation continues until the temperature drops to a certain range, the fan 201a is turned off, the active heat dissipation stops, and only passive heat dissipation is used to reduce the temperature of the headlamp body 102a to the initial state to complete the heat dissipation.

[0186] In summary, by cooperating with the lighting laser source 102b and the focusing lens 102c, the subway train headlights can have the advantages of high brightness, long lighting distance, low energy consumption, etc. under the premise of low energy consumption, thereby improving visibility and energy saving during night driving; and by combining active heat dissipation with passive heat dissipation, the heat dissipation efficiency is greatly improved to ensure the stability and efficiency of the laser system; the laser headlight can improve the headlight system of high-speed trains by making full use of the advantages of laser technology, providing passengers and drivers with a safer and more efficient travel experience.

[0187] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible without substantially departing from the novel teachings and advantages of the subject matter described in the application (e.g., mounting arrangements, use of materials, color, changes in orientation, etc.). For example, the element shown as integrally formed may be composed of a plurality of parts or elements, the position of the element may be inverted or otherwise changed, and the nature or number or position of the discrete element may be altered or changed. Therefore, all such modifications are intended to be included within the scope of the present invention. The order or sequence of any process or method steps may be changed or reordered according to an alternative embodiment. In the claims, any "bracket plus function" clause is intended to cover the structure of the execution function described herein, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the present invention is not limited to a specific embodiment, but extends to a variety of modifications that still fall within the scope of the appended claims.

[0188] Additionally, in an effort to provide a concise description of example embodiments, all features of an actual implementation may not be described.

[0189] It should be understood that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but for those of ordinary skill having the benefit of this disclosure, the development effort will be a routine task of design, fabrication, and production without undue experimentation.

[0190] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for optimizing subway train laser headlights, characterized in that: include, The laser headlights are cooled by convection heat transfer enhancement technology; Optimize the materials of the headlamp body and headlamp mounting ring through COMSOL thermal simulation; White light is generated by compounding RGB red, green and blue laser pump sources through optimizing photoelectric conversion efficiency.

2. The subway train laser headlamp optimization method according to claim 1, characterized in that: The convection heat transfer enhancement technology includes two methods: passive technology and active technology. The passive technology adopts active heat dissipation method, and the active technology adopts passive heat dissipation method. The active and passive combination method is adopted to dissipate heat through thermal convection heat transfer, and the formula is as follows: Φ=hA(t w -t ∞ ) q=Φ / A=h(t w -t ∞ ) Among them, t w represents the solid wall temperature in K; t∞ represents the fluid temperature in K; h is the surface heat transfer coefficient in W / (m 2 K), which characterizes the strength of the convective heat transfer process; Among them, the heat transfer coefficient h and the convection thermal resistance R h Inversely proportional, that is, the convection thermal resistance R h and unit convection thermal resistance r h The expression is as follows: R h =1 / (hA) r h ＝1 / h Where Rh is the convection thermal resistance, rh is the unit convection thermal resistance, and A is the parameter.

3. The subway train laser headlamp optimization method according to claim 2, characterized in that: The COMSOL thermal simulation, when performing thermal simulation, COMSOL uses the control equation to describe the physical phenomenon, and the equation is as follows: Where ρ is the density, c is the specific heat, T is the temperature, k is the thermal conductivity, Q is the volume heat source, and and denote the divergence and gradient operators respectively; Newton's cooling equation can be applied to the model as a boundary condition or initial condition in COMSOL to simulate the convective heat transfer process. The equation is expressed as: q=h(T S -T ∞ ) Where q is the heat flow, h is the convective heat transfer coefficient, T S is the solid surface temperature, T ∞ is the far-field temperature of the fluid.

4. The subway train laser headlamp optimization method as claimed in claim 3, characterized in that: The COMSOL thermal simulation performs a temperature range simulation calculation for thermal convection heat transfer, and forms a COMSOL thermal simulation temperature distribution diagram with the simulation values. The highest temperatures of three heat dissipation materials, 304 stainless steel, iron, and aluminum alloy, are obtained according to the COMSOL thermal simulation, and compared with the temperature range of thermal convection heat transfer, and aluminum alloy is selected as the material of the headlamp body and the headlamp mounting ring.

5. The subway train laser headlamp optimization method according to claim 4, characterized in that: The RGB red, green and blue laser pump sources are combined to produce white light, and the CIE color matching function is used to perform a linear combination of the three primary colors to convert any color into an XYZ color space, where X, Y and Z represent three imaginary primary colors, respectively. The specific formula is as follows: R'=X·Rr+Y·Rg+Z·Rb G'=X·Gr+Y·Gg+Z·Gb B'=X·Rr+Y·Bg+Z·Bb Among them, R, G, B are the synthesized red, green, and blue components, Rr, Gg, Bb are the original red, green, and blue components, and X, Y, and Z are the color matching functions of the CIE standard observer; When synthesizing white light, it is necessary to ensure that the power or intensity of the red, green, and blue lasers are mixed in a certain ratio to produce white light perceived by the human eye. This usually involves weighted summation of the power of each color laser: P total =P r +P g +P b Among them, P total is the total power of the combined light, P r , P g , P b are the powers of red, green and blue lasers respectively; The contribution of each color to the perceived brightness is determined using the CIE color matching functions, which correspond to red, green, and blue with r(λ), g(λ), and b(λ), respectively, and the spectral power distribution of each color laser is Pr(λ), Pg(λ), and Pb(λ), where λ is the wavelength; Integrate the weighted spectral power distribution to get the contribution of each color laser to the total brightness: P' r =∫P r (λ)·r(λ)dλ P' g =∫P g (λ)·g(λ)dλ P' b =∫P b (λ)·b(λ)dλ According to the contribution of each color laser to the total brightness, calculate the required power P of each color laser r , P g , P b : where ω r ,ω g ,ω b are weighting factors for each color of laser light, and they can be adjusted according to the desired white light properties.

6. The subway train laser headlamp optimization method according to claim 5, characterized in that: The photoelectric conversion efficiency is a measure of the ability of a light source to convert electrical energy into light energy, that is, the ratio of output light energy to input electrical energy, and its formula is as follows: Among them, P out is the optical power output by the light source, P in is the optical power input from the light source; The photoelectric conversion efficiency includes pump efficiency, quantum efficiency of fluorescent materials, transmission efficiency of optical systems, and total light conversion efficiency; Among them, the pump efficiency includes calculating the photoelectric conversion efficiency of the pump source, that is, the efficiency of converting electrical energy into laser, and the formula is as follows: Among them, Plaser_out is the laser power output by the laser diode, and Pelectric_in is the electrical power consumed by the laser diode; The quantum efficiency of fluorescent materials includes calculating the efficiency of fluorescent materials absorbing pump light and emitting light. The formula is as follows: Among them, P fluorescence_out is the light power emitted by the fluorescent material, P laser_in is the laser power absorbed by the fluorescent material; The transmission efficiency of an optical system involves calculating the transmission efficiency of light in the optical system from the light source to the final output, including any reflection, absorption or scattering losses. The formula is as follows: Among them, P optical_out is the optical power output by the optical system, P optical_in is the optical power entering the optical system; The total light conversion efficiency involves multiplying the above efficiencies to obtain the light-to-light conversion efficiency of the entire system, as shown below: Among them, P out is the final optical power output after passing through the entire system, P in is the total optical power input by the light source.

7. A subway train laser headlamp, characterized in that: include, A laser emitting unit (100) comprises a fixing component (101) and an illumination component (102) arranged inside the fixing component (101); The heat dissipation unit (200) comprises a heat dissipation component (201) arranged on one side of the fixing component (101).

8. The subway train laser headlamp as claimed in claim 7, characterized in that: The fixing assembly (101) comprises a bottom plate (101a), a fixing ring (101b) arranged on the upper side of the bottom plate (101a), and a mounting ring (101c) arranged on one side of the bottom plate (101a).

9. The subway train laser headlamp as claimed in claim 8, characterized in that: The lighting assembly (102) comprises a headlamp body (102a) arranged on one side of the mounting ring (101c), a lighting lamp laser source (102b) arranged on the inner side of the fixing ring (101b), a focusing lens (102c) arranged on the upper side of the lighting lamp laser source (102b), and a circuit board (102d) arranged on the lower side of the base plate (101a).

10. The subway train laser headlamp as claimed in claim 9, characterized in that: The heat dissipation component (201) comprises a fan (201a) arranged on the inner side of the headlamp body (102a), and a heat dissipation gasket (201b) arranged on the inner side of the fixing ring (101b).

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