JP5360428B2 - Method for estimating surface temperature of exhaust system parts - Google Patents
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Abstract
Description
本発明は、排気系部品の表面温度推定方法に関し、特に、排気系部品として、自動車のエキゾーストマニホールドの表面温度を推定する方法に関する。 The present invention relates to a method for estimating the surface temperature of exhaust system parts, and more particularly to a method for estimating the surface temperature of an exhaust manifold of an automobile as an exhaust system part.
従来、自動車開発期間の短縮並びに低コスト化のため、開発段階で、自動車の排気系部品を始め各部品がどの程度の温度になるかを推定する必要がある。かかる部品温度の推定はできるだけ高精度に行うのが好ましいが、精度を向上させればさせるほど、計算時間が増大する。 Conventionally, in order to shorten the automobile development period and reduce the cost, it is necessary to estimate the temperature of each part including the exhaust system part of the automobile at the development stage. Although it is preferable to estimate the component temperature with as high accuracy as possible, the calculation time increases as the accuracy is improved.
例えば、エキゾーストマニホールドの表面温度を精度よく予測するためには、排気ガスの非定常性、エキゾーストマニホールドからエンジンブロックへの熱伝導を考慮し、非定常伝熱解析を実施する必要がある。しかし、排気ガスの最高流速は音速より速く、固体流体熱連成の非定常解析を発散させないために、微小な時間刻みを与えなければならない。一方、エキゾーストマニホールドの温度変化は遅く、温度安定まで非常に時間がかかり、場合によっては数十分間もかかる場合がある。 For example, in order to accurately predict the surface temperature of the exhaust manifold, it is necessary to perform an unsteady heat transfer analysis in consideration of unsteady exhaust gas and heat conduction from the exhaust manifold to the engine block. However, the maximum flow rate of exhaust gas is faster than the speed of sound, and in order not to diverge the unsteady analysis of solid-fluid thermal coupling, a minute time step must be given. On the other hand, the temperature change of the exhaust manifold is slow, and it takes a very long time to stabilize the temperature, and in some cases, it may take several tens of minutes.
そこで、部品温度の解析をより早期に完了させるものとして、熱伝達率変化の時間平均を演算によって算出して、これを用いて定常計算によって排気管内壁の温度を推定する方法が提案されている（特許文献１参照）。 Therefore, as a method for completing the analysis of the component temperature earlier, a method of calculating the time average of the heat transfer coefficient change by calculation and using this to estimate the temperature of the exhaust pipe inner wall by steady calculation has been proposed. (See Patent Document 1).
しかしながら、特許文献１の方法では、本来非定常計算法によって計算すべきものを定常計算に置き換えているため、精度の面で問題があった。 However, the method of Patent Document 1 has a problem in terms of accuracy because what is originally calculated by the unsteady calculation method is replaced with the steady calculation.
また、解析時間を短縮するために、排気ガスとエキゾーストマニホールド本体を分離し、区切り面で境界条件を互いにマッピングし、流体の熱流場解析において小さい時間刻みを与え、固体の温度解析において大きい時間刻みを与える手法もあるが、マッピングが難しく精度が落ちる可能性があり、構造が複雑なエキゾーストマニホールドへの対応は困難であった。 Also, in order to shorten the analysis time, the exhaust gas and the exhaust manifold main body are separated, the boundary conditions are mapped to each other on the partition surface, a small time step is given in the heat flow field analysis of the fluid, and a large time step in the solid temperature analysis However, mapping is difficult and accuracy may be reduced, making it difficult to handle exhaust manifolds with complex structures.
本発明は、上記事情に鑑み、排気系部品の表面温度を、高精度で、かつ高速に推定することができる排気系部品の表面温度推定方法を提供することを目的とする。 In view of the above circumstances, an object of the present invention is to provide a method for estimating the surface temperature of an exhaust system component that can estimate the surface temperature of the exhaust system component with high accuracy and at high speed.
上記目的を達成する本発明の第１の態様は、内部に排気ガスが流通する排気系部品の表面温度を推定する排気系部品の表面温度推定方法であって、排気系部品の非定常熱伝導方程式を用い、当該排気系部品の熱拡散率を実際の数値より大きく設定して表面温度を算出することを特徴とする排気系部品の表面温度推定方法にある。 A first aspect of the present invention that achieves the above object is a method for estimating the surface temperature of an exhaust system component that estimates the surface temperature of the exhaust system component through which exhaust gas flows, and the non-steady heat conduction of the exhaust system component An exhaust system component surface temperature estimation method is characterized in that an equation is used to calculate a surface temperature by setting a thermal diffusivity of the exhaust system component to be larger than an actual numerical value.
かかる第１の態様では、熱拡散率を実際より大きく設定することにより、安定温度に至るまでの時間を大幅に短縮することにより計算時間を大幅に低減することができる。 In the first aspect, by setting the thermal diffusivity larger than the actual one, it is possible to significantly reduce the calculation time by significantly reducing the time to reach the stable temperature.
本発明の第２の態様は、前記非定常熱伝導方程式が下記式（１）で表され、式（２）で表される境界条件を用い、排気系部品の熱拡散率（λ／ρ・ｃ）を実際の数値より大きく設定して表面温度を算出することを特徴とする請求項１に記載の排気系部品の表面温度推定方法にある。 In the second aspect of the present invention, the unsteady heat conduction equation is represented by the following equation (1), and the boundary condition represented by the equation (2) is used, and the thermal diffusivity (λ / ρ · 2. The exhaust system part surface temperature estimation method according to claim 1, wherein the surface temperature is calculated by setting c) larger than an actual numerical value.
ｃ：排気系部品の比熱、ρ：排気系部品の密度、λ：排気系部品の熱伝導率、ｑｓ：熱流束、ｎ：法線方向 c: specific heat of exhaust system parts, ρ: density of exhaust system parts, λ: thermal conductivity of exhaust system parts, qs: heat flux, n: normal direction
かかる第２の態様では、所定の非定常熱伝導方程式を用いて、熱拡散率を実際より大きく設定することにより、安定温度に至るまでの時間を大幅に短縮することにより計算時間を大幅に低減することができる。 In the second aspect, by using a predetermined unsteady heat conduction equation and setting the thermal diffusivity larger than the actual one, the time to reach a stable temperature is greatly shortened, thereby greatly reducing the calculation time. can do.
本発明の第３の態様は、熱拡散率を実際の数値の１０倍から１０００倍の数値とすることを特徴とする第１又は２の態様に記載の排気系部品の表面温度推定方法にある。 A third aspect of the present invention is the exhaust system part surface temperature estimation method according to the first or second aspect, wherein the thermal diffusivity is set to a value that is 10 to 1000 times the actual value. .
かかる第３の態様では、熱拡散率を１０倍から１０００倍の数値とすることにより、演算時間を約１／１０〜１／１０００程度に短縮することができる。 In the third aspect, the calculation time can be reduced to about 1/10 to 1/1000 by setting the thermal diffusivity to a numerical value of 10 to 1000 times.
本発明の第４の態様では、前記排気系部品の比熱又は密度を実際の数値より小さく設定することにより、熱拡散率を大きくすることを特徴とする第１〜３の何れか１つの態様に記載の排気系部品の表面温度推定方法にある。 In a fourth aspect of the present invention, in any one of the first to third aspects, the thermal diffusivity is increased by setting the specific heat or density of the exhaust system component to be smaller than an actual numerical value. It is in the surface temperature estimation method of the exhaust system part of description.
かかる第４の態様では、比熱ｃ又は密度ρを実際の数値より小さくすることにより熱拡散率を大きく設定することができ、境界条件を変更することなく、非定常伝熱解析を行うことができる。 In the fourth aspect, the thermal diffusivity can be set large by making the specific heat c or density ρ smaller than the actual numerical value, and unsteady heat transfer analysis can be performed without changing the boundary conditions. .
本発明の第５の態様は、算出された温度の一周期内の時間平均温度を表面温度とすることを特徴とする第１〜４の何れか１つの態様に記載の排気系部品の表面温度推定方法にある。 According to a fifth aspect of the present invention, the surface temperature of the exhaust system component according to any one of the first to fourth aspects is characterized in that the time average temperature within one cycle of the calculated temperature is defined as the surface temperature. In the estimation method.
かかる第５の態様では、表面温度を一周期内の時間平均温度として算出することにより、熱拡散率を大きく変えても、推定温度の精度を保つことができる。 In the fifth aspect, by calculating the surface temperature as the time average temperature within one cycle, the accuracy of the estimated temperature can be maintained even if the thermal diffusivity is greatly changed.
本発明によれば、非定常伝熱解析において熱拡散率を実際より大きく設定することにより、精度を保ったまま、高速解析を行うことができ、排気系の表面温度を、高精度で、かつ高速に推定することができる排気系部品の表面温度推定方法が提供される。 According to the present invention, by setting the thermal diffusivity larger than actual in the unsteady heat transfer analysis, high-speed analysis can be performed while maintaining accuracy, the surface temperature of the exhaust system can be set with high accuracy, and A method for estimating the surface temperature of an exhaust system component that can be estimated at high speed is provided.
以下、本発明を詳細に説明する。 Hereinafter, the present invention will be described in detail.
本発明の排気系部品の表面温度推定方法は、内部に排気ガスが流通する排気系部品の表面温度を推定するためのものであり、例えば、自動車のエキゾーストマニホールドの表面温度を推定するために好適に用いることができる。以下、エキゾーストマニホールドを例にとって説明する。 The method for estimating the surface temperature of an exhaust system component of the present invention is for estimating the surface temperature of an exhaust system component in which exhaust gas circulates. For example, the method is suitable for estimating the surface temperature of an exhaust manifold of an automobile. Can be used. Hereinafter, the exhaust manifold will be described as an example.
エキゾーストマニホールドは、形状が複雑で、シリンダーヘッドへの伝熱も無視できないので、その表面温度を推定するためにはエキゾーストマニホールド本体の熱伝導解析が必要になるが、内部を流れる排気ガスの非定常性がエキゾーストマニホールド表面の温度分布に与える影響が大きいので、非定常解析を行わないと正しい温度分布が得られない。 The exhaust manifold is complicated in shape and the heat transfer to the cylinder head cannot be ignored.To estimate the surface temperature of the exhaust manifold, it is necessary to analyze the heat transfer of the exhaust manifold body. The effect on the temperature distribution of the exhaust manifold surface is large, so the correct temperature distribution cannot be obtained unless a transient analysis is performed.
エキゾーストマニホールドの物性値である比熱ｃ、密度ρ、及び熱伝導率λが一定であり、且つ内部発熱がない場合には，非定常熱伝導方程式は下記式（１）のように表される。 When the specific heat c, density ρ, and thermal conductivity λ, which are physical properties of the exhaust manifold, are constant and there is no internal heat generation, the unsteady heat conduction equation is expressed as the following equation (1).
また、境界条件は、下記式（２）で表される。 The boundary condition is expressed by the following formula (2).
ここで、ｑｓは熱流束、ｎは法線方向を表す。 Here, q s represents the heat flux, and n represents the normal direction.
本発明では、かかる非定常熱伝導方程式で表面温度を推定するにあたって、熱拡散率（λ／ρ・ｃ）を大きく設定すれば、すなわち、熱伝導率λを大きく設定するか、密度ρ又は比熱ｃを小さく設定して解析を行う。かかる本発明は、熱拡散率を実際の数値より大きく設定すれば、エキゾーストマニホールドが安定温度に至るまでの温度を短縮することができ、これにより、解析のための演算時間を大幅に短縮することができるが、推定される表面温度には大きな影響が出ないという知見に基づくものである。 In the present invention, in estimating the surface temperature by such an unsteady heat conduction equation, if the thermal diffusivity (λ / ρ · c) is set large, that is, the thermal conductivity λ is set large, the density ρ or the specific heat. Analysis is performed by setting c small. In the present invention, if the thermal diffusivity is set larger than the actual numerical value, the temperature until the exhaust manifold reaches a stable temperature can be shortened, thereby greatly reducing the calculation time for analysis. However, this is based on the knowledge that the estimated surface temperature has no significant effect.
ここで、熱拡散率をどの程度大きく設定するかは、演算時間の短縮の程度と、推定される表面温度への影響の度合いとを考慮して設定すればよい。例えば、演算時間は、熱拡散率を１０倍に設定すると、おおよそ１／１０程度、１００倍に設定すると、１／１００程度、１０００倍に設定すると、１／１０００程度に短縮でき、また、１００倍に設定した場合には、推定温度は十分な精度を保っているので、目的に応じて設定すればよい。熱拡散率を１０倍に設定すれば、十分な効果が得られ、また、１０００倍に設定しても、精度上問題ないので、熱拡散率を１０〜１０００倍程度に設定するのが好ましいが、これに限定されるものではない。 Here, how large the thermal diffusivity is set may be set in consideration of the degree of shortening the calculation time and the estimated degree of influence on the surface temperature. For example, when the thermal diffusivity is set to 10 times, the computation time can be reduced to about 1/10, when set to 100 times, about 1/100, when set to 1000 times, it can be reduced to about 1/1000, When set to double, the estimated temperature maintains sufficient accuracy, and may be set according to the purpose. If the thermal diffusivity is set to 10 times, a sufficient effect can be obtained, and even if it is set to 1000 times, there is no problem in accuracy, so it is preferable to set the thermal diffusivity to about 10 to 1000 times. However, the present invention is not limited to this.
また、熱拡散率を大きく設定する場合、熱伝導率λを大きく設定すると、式（２）で表される境界条件も変化してしまうので、密度ρ又は比熱ｃを小さく設定するのが好ましい。 Further, when the thermal diffusivity is set to be large, if the thermal conductivity λ is set to be large, the boundary condition represented by the equation (2) is also changed. Therefore, it is preferable to set the density ρ or the specific heat c to be small.
また、熱拡散率の設定倍率を１０倍程度にしても、周期性の入力条件に対して、安定時の表面温度変化がほとんどなかったが、熱拡散率の設定倍率をさらに大きくすると、表面温度の振動周期は変わらないが、温度振幅が大きくなることが後述する解析結果からわかった。しかしながら、この場合にも、安定時における１周期内のモニタ点の時間平均温度を算出すると、熱拡散率を大きく変化させても、平均温度の変化は大きくないので、これを表面温度とすればよいことがわかった。 Even when the thermal diffusivity setting magnification was about 10 times, there was almost no change in the surface temperature at the time of stability with respect to the periodic input conditions. However, when the thermal diffusivity setting magnification was further increased, the surface temperature From the analysis results described later, it was found that the temperature amplitude increases, although the vibration period of the above does not change. However, in this case as well, if the time average temperature of the monitoring points within one cycle at the stable time is calculated, even if the thermal diffusivity is largely changed, the change in the average temperature is not large. I found it good.
（解析例：簡易モデル解析）
図１に示す排気ガスとステンレスパイプの簡易モデルを利用し、非定常熱連成解析にて熱拡散率と温度変化との関係を求めた。
(Example of analysis: Simple model analysis)
Using the simple model of exhaust gas and stainless steel pipe shown in FIG. 1, the relationship between thermal diffusivity and temperature change was obtained by unsteady thermal coupled analysis.
簡易モデルは、ステンレスパイプ１の入口２側及び出口３側に流体としての空気の入口助走空間４及び出口助走空間５を配置し、ステンレスパイプ１の外壁面に１０箇所のモニタポイント６１〜６１０を設けたものである。解析条件は、ステンレスパイプ１の入口２側の入口助走空間４の流体に、周期２π×０．０１秒の正弦波の温度と流速条件を与え、ステンレスパイプ１の外壁面のモニタポイント６１〜６１０の時系列変化を出力するものとした。そして、ステンレスパイプ１の熱拡散率を１０倍、１００倍、１０００倍に設定し、入口２近くで非定常性の影響を受けやすいモニタポイント６１の温度変化と、熱拡散率の倍率との関係を図２に示す。解析例１〜３は、熱拡散率をそれぞれ１０倍、１００倍、１０００倍としたものであり、比較解析例は実際の熱拡散率として算出した例である。詳細は、以下の通りである。 In the simple model, an inlet run-up space 4 and an exit run-up space 5 of air as fluid are arranged on the inlet 2 side and the outlet 3 side of the stainless steel pipe 1, and 10 monitor points 6 1 to 6 on the outer wall surface of the stainless steel pipe 1. 10 is provided. As analysis conditions, a temperature and flow rate condition of a sine wave with a period of 2π × 0.01 seconds are given to the fluid in the inlet run-up space 4 on the inlet 2 side of the stainless steel pipe 1, and the monitor points 6 1 to 6 on the outer wall surface of the stainless steel pipe 1. 6 10 Time series changes were output. Then, 10 times the thermal diffusivity of the stainless steel pipe 1, 100-fold, and set to 1000 times, with an inlet 2 close and the temperature change of the non-stationarity sensitive monitor point 61, the thermal diffusivity ratio and the The relationship is shown in FIG. In Analysis Examples 1 to 3, the thermal diffusivity is 10 times, 100 times, and 1000 times, respectively, and the comparative analysis example is an example calculated as an actual thermal diffusivity. Details are as follows.
比較解析例：ステンレスパイプ１の密度、熱伝導率、比熱を不変としたもの
解析例１：密度を０．１倍、すなわち、熱拡散率を１０倍としたモデル
解析例２：密度を０．０１倍、すなわち、熱拡散率を１００倍としたモデル
解析例３：密度を０．００１倍、すなわち、熱拡散率を１０００倍としたモデル
解析条件
解析タイプ ：非定常解析
乱流モデル ：応力乱流モデル
時間刻み ：０．００１Ｓｅｃ
壁関数 ：標準壁関数
ガス密度 ：温度関数
管壁壁面条件 ：温度と熱抵抗一定
出口条件 ：自然流出
初期温度条件 ：２０℃
固体物性 ：ステンレス
：熱伝導率λ：４３Ｗ／ｍＫ
：密度ρ：７８００ｋｇ／ｍ３
：比熱ｃ：４７５Ｊ／ｋｇＫ
流体物性 ：空気
Comparative analysis example: the density, thermal conductivity, and specific heat of the stainless steel pipe 1 are unchanged. Analysis example 1: model in which the density is 0.1 times, that is, the thermal diffusivity is 10 times. 01 times, that is, model with thermal diffusivity 100 times Analysis example 3: Model with density 0.001 times, ie, thermal diffusivity 1000 times Analysis conditions Analysis type: Unsteady analysis Turbulence model: Stress turbulence Flow model time step: 0.001Sec
Wall function: Standard wall function Gas density: Temperature function Tube wall surface condition: Constant temperature and thermal resistance Exit condition: Natural outflow Initial temperature condition: 20 ℃
Solid physical properties: Stainless steel
: Thermal conductivity λ: 43 W / mK
: Density ρ: 7800 kg / m 3
: Specific heat c: 475 J / kgK
Fluid physical properties: Air
図２の結果より、ステンレスパイプ１の熱拡散率を１０倍程度まで拡大した場合、すなわち、解析例１の場合には、周期性の入力条件に対し、安定時のパイプ外表面温度であるモニタポイント６１の温度が比較解析例とほとんど同じで、温度変化がほとんどなかったが、熱拡散率の設定倍率を大きくすると、その振動周期は変わらないが、温度振幅が大きくなるが、安定時における１周期内のモニタポイント６１の時間平均温度を算出すると、変化が極めて小さいことがわかった。 From the result of FIG. 2, when the thermal diffusivity of the stainless steel pipe 1 is increased to about 10 times, that is, in the case of Analysis Example 1, the monitor is the pipe outer surface temperature at the time of stability with respect to the periodic input condition. Point 61 The temperature at 1 was almost the same as the comparative analysis example, and there was almost no temperature change, but when the thermal diffusivity setting magnification was increased, the oscillation period did not change, but the temperature amplitude increased, but at the stable time When calculating the time average temperature of the monitoring point 6 1 in one period, it was found that the change is very small.
例えば、解析例２では、モニタポイント６１の温度振幅が数百倍に増大するが、安定時における１周期内のモニタポイント６１の時間平均温度の変化は、２℃以内であった。 For example, the second analyzing example, the temperature amplitude of the monitor points 61 is increased to several hundred times, changes in the time-averaged temperature of the monitoring point 6 1 in one period in the stable time was within 2 ° C..
よって、ステンレスパイプ１の熱拡散率の倍率を大きく変えた解析例２、３、特に解析例３の場合には、表面温度として１周期内の時間平均温度を採用するのがよいことがわかった。 Therefore, in the case of analysis examples 2 and 3 in which the magnification of the thermal diffusivity of the stainless steel pipe 1 is greatly changed, especially analysis example 3, it was found that the time average temperature within one cycle should be adopted as the surface temperature. .
図３には、熱拡散率の倍率と、演算時間と、平均温度との関係を示す。 図３から、さらに、温度安定までのコンピュータの演算時間は、ステンレスパイプ１の熱拡散率の倍率との逆比例関係があることがわかった。従って、平均温度を表面温度とすれば、ステンレスパイプ１の熱拡散率の倍率を大きくしても、解析精度を保持しながら、熱連成の計算時間を大幅に短縮できることがわかった。 FIG. 3 shows the relationship between the thermal diffusivity magnification, the calculation time, and the average temperature. From FIG. 3, it was further found that the computing time until the temperature was stabilized had an inversely proportional relationship with the magnification of the thermal diffusivity of the stainless steel pipe 1. Therefore, it was found that if the average temperature is the surface temperature, the calculation time of the thermal coupling can be greatly shortened while maintaining the analysis accuracy even if the magnification of the thermal diffusivity of the stainless pipe 1 is increased.
（実施例）
上述した簡易モデル解析で得た結論に従い、エキゾーストマニホールドの熱拡散率を大きく設定し、以下の通り、非定常解析を行った。なお、乱流モデルは他のモデルを利用しても同様な結果になることがわかっている。
(Example)
In accordance with the conclusion obtained by the simple model analysis described above, the thermal diffusivity of the exhaust manifold was set large, and the unsteady analysis was performed as follows. It is known that the turbulent flow model gives the same result even when other models are used.
本実施例の解析条件は以下の通りである。 The analysis conditions of this example are as follows.
Analysis mode： Transient
Turbulence model： k-ε/RNG
Inlet conditions： Instantaneous T，V，Density
Outlet conditions： Instantaneous pressure
Wall conditions： Heat flux
Flange conditions： Constant T & Thermal resistance
Exhaust manifold properties： Thermal diffusivity is Expanded
Analysis mode: Transient
Turbulence model: k-ε / RNG
Inlet conditions: Instantaneous T, V, Density
Outlet conditions: Instantaneous pressure
Wall conditions: Heat flux
Flange conditions: Constant T & Thermal resistance
Exhaust manifold properties: Thermal diffusivity is Expanded
予備解析結果のアウトプットファイルを利用し、エキゾーストマニホールドの外壁面における周辺との対流輻射熱交換の境界条件を設定した。なお、この解析を車体フルモデル解析に用いる場合に、車体モデルとエキゾーストマニホールドモデルの計算格子サイズが違う場合でも高精度に整合できるため、空間３点補間のマッピングプログラムにより、格子を作成した。また、冷却されているシリンダーヘッドの温度はほぼ一定で、エキゾーストマニホールドとヘッドの締め付けトルクから接触熱抵抗を算出し、エキゾーストマニホールドフランジの熱伝導境界条件を設定した。最終の表面温度分布については、安定時の１サイクル内の各境界セルの時間平均値を算出し、表面計算格子に与えて表示した。 Using the output file of the preliminary analysis results, boundary conditions for convective radiant heat exchange with the surroundings on the outer wall of the exhaust manifold were set. When this analysis is used for full body model analysis, even if the calculation lattice sizes of the vehicle body model and the exhaust manifold model are different, the lattice can be created with a spatial three-point interpolation mapping program. In addition, the temperature of the cylinder head being cooled was almost constant, the contact thermal resistance was calculated from the tightening torque of the exhaust manifold and the head, and the heat conduction boundary condition of the exhaust manifold flange was set. For the final surface temperature distribution, the time average value of each boundary cell within one cycle at the time of stabilization was calculated and displayed on the surface calculation grid.
この結果を図４に示す。 The result is shown in FIG.
エキゾーストマニホールドの密度を１／１０００として解析した結果、温度安定までの時間は、通常の非定常解析では約１０００秒であるところ、約１秒であり、演算時間は、予想で約２．５年であるところ、約２２時間であった。 As a result of analyzing the density of the exhaust manifold as 1/1000, the time until temperature stabilization is about 1000 seconds in the normal unsteady analysis, but about 1 second, and the calculation time is about 2.5 years as expected. It was about 22 hours.
また、エキゾーストマニホールド表面のいくつかのモニタポイントにおける温度の解析結果と、実際の測定試験結果と比較した。この結果を図５に示す。 In addition, the temperature analysis results at several monitor points on the exhaust manifold surface were compared with the actual measurement test results. The result is shown in FIG.
図５の結果によると絶対温度の誤差が最大６％で、温度分布の傾向も大体一致しており、良好な精度が確認できた。 According to the results of FIG. 5, the absolute temperature error was 6% at the maximum, and the tendency of the temperature distribution was almost the same, and good accuracy could be confirmed.
この結果、演算時間を１／１０００程度に短縮しても、解析精度を維持できることが確認された。 As a result, it was confirmed that the analysis accuracy can be maintained even when the calculation time is reduced to about 1/1000.
なお、このようなエキゾーストマニホールド解析で得た表面時間平均温度は、車体フルモデル解析に使用する場合、平均温度をアウトプットファイルに書き出し、車体フルモデルの本解析に用いることができる。 In addition, when the surface time average temperature obtained by such an exhaust manifold analysis is used for the vehicle body full model analysis, the average temperature can be written in an output file and used for the main analysis of the vehicle body full model.
図６には、モニタポイント８点の瞬時温度と平均温度の変化を示した。 FIG. 6 shows changes in instantaneous temperature and average temperature at 8 monitor points.
この結果、基礎検討モデルと同じように、瞬時温度は変化していること、並びに１サイクル内の平均温度は短時間で安定になっていることが確認された。 As a result, as in the basic study model, it was confirmed that the instantaneous temperature was changed and that the average temperature in one cycle was stable in a short time.
本発明の排気系部品の表面温度推定方法は、自動車の排気系部品の表面温度、特にエキゾーストマニホールドの表面温度の推定の他、各種交通機関や産業機械の部品であって内部に排気ガスが流れて非定常性を有する排気系部品の表面温度を推定する場合に適用できる。 The method for estimating the surface temperature of exhaust system parts according to the present invention is used to estimate the surface temperature of exhaust system parts of automobiles, in particular, the surface temperature of exhaust manifolds, as well as various transportation and industrial machine parts. This can be applied to the estimation of the surface temperature of exhaust system parts having non-stationarity.
１ ステンレスパイプ
２ 入口
３ 出口
４ 入口助走空間
５ 出口助走空間
６１〜６１０ モニタポイント
1 stainless steel pipe 2 inlet 3 outlet 4 inlets approach the space 5 exit runway space 61 through 10 monitor points
Claims (5)
排気系部品の非定常熱伝導方程式を用い、当該排気系部品の熱拡散率を実際の数値より大きく設定して表面温度を算出することを特徴とする排気系部品の表面温度推定方法。 A method for estimating the surface temperature of an exhaust system part for estimating the surface temperature of an exhaust system part through which exhaust gas flows,
A method for estimating a surface temperature of an exhaust system component, wherein the surface temperature is calculated using an unsteady heat conduction equation of the exhaust system component and setting a thermal diffusivity of the exhaust system component to be larger than an actual numerical value.
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