Method and system for measuring and calculating extra cold start emission of automobile in plateau low-temperature environment

Abstract

The invention discloses a method and a system for measuring and calculating extra cold start emission of an automobile in a plateau low-temperature environment. The method comprises the following steps: acquiring engine operation parameter data, environment temperature data and instantaneous emission data; calculating additional cold start emission according to cold start emission and thermal stable operation emission of the heavy-duty hybrid electric vehicle in the plateau low-temperature environment and the number of times of occurrence of the additional cold start emission; an oil injection factor is calculated according to the oil injection quantity during cold start and the oil injection quantity during thermal stable operation of the automobile; calculating a low-temperature factor according to the environment temperature of the heavy hybrid electric vehicle in the low-temperature environment and the environment temperature of the heavy hybrid electric vehicle in the normal-temperature environment; calculating an exhaust temperature factor according to the exhaust temperature and the cold start exhaust temperature of the heavy-duty hybrid electric vehicle in the specific stage; calculating additional cold start comprehensive emission according to the additional cold start emission, the oil injection factor, the low temperature factor and the exhaust temperature factor; and the environmental adaptability of the vehicle is improved, and effective emission control can be ensured to be realized in a severe environment.

Description

Technical Field

[0001] This invention belongs to the field of automotive cold start emission calculation technology, and more specifically, relates to a method and system for calculating additional cold start emissions of automobiles in high-altitude and low-temperature environments. Background Technology

[0002] Against the backdrop of reducing pollution and carbon emissions in the transportation sector, heavy-duty hybrid vehicles (HEVs) have been widely adopted in numerous scenarios due to their advantages such as reduced fuel consumption, improved fuel efficiency, reduced emissions, and enhanced energy utilization. However, the unique operating mechanism of HEVs also brings certain problems. Because of their working principle, the engine warm-up time and after-treatment processing time are extended, resulting in additional emissions during cold starts. This additional cold-start emission phenomenon is particularly pronounced in high-altitude, low-temperature environments, with a significant increase in emissions.

[0003] Currently, there are still many shortcomings in the calculation methods for additional cold-start emissions of heavy-duty hybrid electric vehicles (HEVs) in high-altitude and low-temperature environments. Existing technologies fail to fully consider the combined effects of fuel injection quantity, ambient temperature, and exhaust temperature on these emissions. This makes it impossible for existing calculation methods to accurately reflect the true emissions of HEVs in such environments, thus affecting the formulation and optimization of emission control strategies for HEVs in these special conditions.

[0004] Therefore, there is an urgent need for a method that can accurately measure the additional cold-start emissions of heavy-duty hybrid vehicles in high-altitude and low-temperature environments. Summary of the Invention

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a method and system for calculating additional cold-start emissions of automobiles in high-altitude and low-temperature environments. This method comprehensively considers the impact of fuel injection quantity, ambient temperature, and exhaust temperature on additional cold-start emissions of heavy-duty hybrid vehicles in high-altitude and low-temperature environments, enabling accurate calculation of these emissions. This has significant practical implications for improving the emission control system for hybrid vehicles and promoting further development of pollution reduction and carbon reduction efforts in the transportation sector.

[0006] To achieve the above objectives, one aspect of the present invention provides a method for calculating additional cold-start emissions from automobiles in high-altitude and low-temperature environments, comprising the following steps:

[0007] S1: Acquire engine operating parameter data, ambient temperature data, and instantaneous emission data of a heavy-duty hybrid vehicle in a high-altitude, low-temperature environment; engine operating parameters include engine coolant temperature, exhaust temperature, and fuel injection quantity; the instantaneous emission data includes instantaneous cold start emission data and instantaneous thermal stable operation emission data;

[0008] S2: Calculate the additional cold start emissions of heavy-duty hybrid electric vehicles in high-altitude and low-temperature environments based on the cold start emissions and thermal stability operation emissions of the heavy-duty hybrid electric vehicles in high-altitude and low-temperature environments, as well as the number of times additional cold start emissions occur.

[0009] S3: Calculate the fuel injection factor of a heavy-duty hybrid electric vehicle under high-altitude and low-temperature conditions based on the fuel injection quantity during cold start and during thermal stable operation.

[0010] S4: Calculate the low temperature factor of heavy-duty hybrid vehicles in low-temperature environments and normal-temperature environments based on the ambient temperature of heavy-duty hybrid vehicles in low-temperature environments.

[0011] S5: Calculate the exhaust temperature factor of a heavy-duty hybrid vehicle in a high-altitude, low-temperature environment based on the exhaust temperature and cold-start exhaust temperature of the heavy-duty hybrid vehicle at a specific stage.

[0012] S6: Calculate the combined additional cold start emissions of the heavy-duty hybrid vehicle under high-altitude and low-temperature conditions based on the additional cold start emissions of the heavy-duty hybrid vehicle under high-altitude and low-temperature conditions, the fuel injection factor, the low-temperature factor, and the exhaust temperature factor.

[0013] Furthermore, the calculation of cold start emissions for heavy-duty hybrid vehicles in high-altitude, low-temperature environments in step S2 includes:

[0014] The cold start stage of a heavy-duty hybrid electric vehicle in a high-altitude, low-temperature environment is determined based on the engine coolant temperature. The cold start emissions of the heavy-duty hybrid electric vehicle in a high-altitude, low-temperature environment are calculated based on the time required for the cold start stage and the instantaneous cold start emissions.

[0015] When the engine coolant temperature does not exceed 70°C, it is considered to be in the cold start stage;

[0016] In step S2, the additional cold start emissions of heavy-duty hybrid vehicles in high-altitude low-temperature environments are calculated using equation (1):

[0017]

[0018] in, This represents the average additional cold-start emissions of heavy-duty hybrid vehicles operating in high-altitude, low-temperature environments. This represents the average cold-start emissions of heavy-duty hybrid electric vehicles operating in high-altitude, low-temperature environments. is the average thermally stable operating emission of a heavy-duty hybrid electric vehicle in a high-altitude, low-temperature environment; T is the number of times a heavy-duty hybrid electric vehicle experiences additional cold-start emissions in a high-altitude, low-temperature environment.

[0019] Furthermore, the calculation of thermally stable operating emissions of heavy-duty hybrid vehicles in high-altitude, low-temperature environments in step S2 includes:

[0020] Based on exhaust temperature, determine the different sub-stages and corresponding operating time ranges of thermal stability operation of heavy-duty hybrid vehicles in high-altitude and low-temperature environments.

[0021] The thermal stable operation emissions of heavy-duty hybrid electric vehicles in different sub-stages of thermal stable operation are calculated based on the instantaneous thermal stable operation emissions of different sub-stages of thermal stable operation and the corresponding operating time ranges in high-altitude low-temperature environments.

[0022] The thermally stable operating emissions of heavy-duty hybrid electric vehicles in different sub-stages are summed to calculate the thermally stable operating emissions of heavy-duty hybrid electric vehicles in high-altitude and low-temperature environments.

[0023] When the engine coolant temperature is greater than 70°C, it is considered to be in the thermally stable operation stage; when the exhaust temperature reaches 200°C, it is a sub-stage; when the exhaust temperature is greater than 200°C, it is another sub-stage.

[0024] Furthermore, the thermally stable operating emissions of the heavy-duty hybrid vehicle are calculated using equation (3):

[0025]

[0026] in, The average thermally stable operating emissions of heavy-duty hybrid electric vehicles in high-altitude and low-temperature environments; The average thermally stable emission values ​​of heavy-duty hybrid vehicle engines operating at temperatures above 70°C and exhaust temperatures reaching 200°C in high-altitude and low-temperature environments. The average thermally stable emission values ​​for heavy-duty hybrid vehicle engines operating at temperatures above 70°C and above 200°C in high-altitude, low-temperature environments.

[0027] Furthermore, the thermally stable operating emissions of heavy-duty hybrid vehicle engines operating at temperatures exceeding 70°C and exhaust temperatures reaching 200°C under high-altitude and low-temperature conditions are calculated using equation (4):

[0028]

[0029] Among them, t ET =200℃ is the time it takes for the exhaust temperature of a heavy-duty hybrid vehicle to reach 200℃ in a high-altitude, low-temperature environment; E a，i For heavy-duty hybrid vehicle engines operating under conditions of high altitude and low temperature, where the engine coolant temperature exceeds 70°C and the exhaust temperature reaches 200°C, instantaneous thermally stable emissions are required. 冷 The time required for the engine coolant temperature of a heavy-duty hybrid vehicle to reach 70°C in a high-altitude, low-temperature environment.

[0030] The thermally stable operating emissions of heavy-duty hybrid vehicle engines operating at temperatures above 70°C and above 200°C under high-altitude and low-temperature conditions are calculated using equation (5):

[0031]

[0032] Among them, E b，i For heavy-duty hybrid vehicle engines operating under conditions of high altitude and low temperature, where the engine coolant temperature exceeds 70℃ and the exhaust temperature exceeds 200℃, the instantaneous thermally stable emission is required. n This refers to the time when the thermal stability operation of a heavy-duty hybrid vehicle ends in a high-altitude, low-temperature environment.

[0033] Furthermore, in step S3, the fuel injection factor of the heavy-duty hybrid vehicle under high-altitude low-temperature conditions is calculated using equation (6):

[0034]

[0035] Where f is the fuel injection factor of a heavy-duty hybrid vehicle operating in high-altitude, low-temperature environments, F 冷 This refers to the fuel injection quantity during cold start of a heavy-duty hybrid vehicle in high-altitude, low-temperature environments; F 热 This refers to the fuel injection quantity for heavy-duty hybrid vehicles operating under thermal stability conditions in high-altitude and low-temperature environments.

[0036] Furthermore, in step S4, the low-temperature factor of the heavy-duty hybrid vehicle under high-altitude low-temperature conditions is calculated using equation (7):

[0037]

[0038] Where w is the low-temperature factor of a heavy-duty hybrid vehicle in a high-altitude, low-temperature environment, W 低 The ambient temperature for heavy-duty hybrid vehicles in low-temperature environments; W 常 The ambient temperature for heavy-duty hybrid vehicles under normal temperature conditions.

[0039] Furthermore, in step S5, the exhaust temperature factor of the heavy-duty hybrid vehicle under high-altitude low-temperature conditions is calculated using equation (8):

[0040]

[0041] Where et is the exhaust temperature factor (ET) of a heavy-duty hybrid vehicle operating in low-temperature, high-altitude environments; 冷 The cold start exhaust temperature (ET) of a heavy-duty hybrid vehicle operating in low-temperature, high-altitude environments; kThis indicates the exhaust temperature at a specific stage; the specific stage includes the cold start stage of a heavy-duty hybrid vehicle in a high-altitude and low-temperature environment, the thermally stable operation stage with engine coolant temperature greater than 70°C and exhaust temperature reaching 200°C, or the thermally stable operation stage with engine coolant temperature greater than 70°C and exhaust temperature greater than 200°C.

[0042] Furthermore, the additional cold-start combined emissions of the heavy-duty hybrid vehicle in the high-altitude low-temperature environment described in step S6 are calculated using equation (9):

[0043]

[0044] in, This represents the average combined emissions from additional cold starts of heavy-duty hybrid vehicles operating in high-altitude, low-temperature environments.

[0045] A second aspect of the present invention provides a system for calculating additional cold-start emissions from automobiles in high-altitude and low-temperature environments, used to implement the aforementioned method for calculating additional cold-start emissions from automobiles in high-altitude and low-temperature environments, comprising:

[0046] The data acquisition module is used to acquire engine operating parameter data, ambient temperature data, and instantaneous emission data of heavy-duty hybrid vehicles in high-altitude and low-temperature environments. The engine operating parameters include engine coolant temperature, exhaust temperature, and fuel injection quantity. The instantaneous emission data includes instantaneous cold start emission data and instantaneous thermal stable operation emission data.

[0047] The additional cold start emission calculation module is used to calculate the additional cold start emission of heavy-duty hybrid vehicles in high-altitude and low-temperature environments based on the cold start emission and thermal stability operation emission of the heavy-duty hybrid vehicles in high-altitude and low-temperature environments, as well as the number of times additional cold start emission occurs.

[0048] The fuel injection factor calculation module is used to calculate the fuel injection factor of a heavy-duty hybrid vehicle under high-altitude and low-temperature conditions based on the fuel injection quantity during cold start and during thermal stable operation.

[0049] The low-temperature factor calculation module is used to calculate the low-temperature factor of heavy-duty hybrid vehicles in high-altitude low-temperature environments based on the ambient temperature in low-temperature environments and ambient temperature in normal environments.

[0050] The exhaust temperature factor calculation module is used to calculate the exhaust temperature factor of a heavy-duty hybrid vehicle in a high-altitude and low-temperature environment based on the exhaust temperature and cold start exhaust temperature of the heavy-duty hybrid vehicle at a specific stage.

[0051] The integrated emissions calculation module is used to calculate the additional cold start integrated emissions of the heavy-duty hybrid vehicle under high-altitude and low-temperature conditions based on the additional cold start emissions of the heavy-duty hybrid vehicle under high-altitude and low-temperature conditions, the fuel injection factor, the low-temperature factor, and the exhaust temperature factor.

[0052] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0053] The present invention provides a method and system for calculating additional cold-start emissions from a vehicle in a high-altitude, low-temperature environment. This method calculates the additional cold-start emissions of a heavy-duty hybrid vehicle in a high-altitude, low-temperature environment based on its cold-start emissions and thermally stable operation emissions, as well as the number of times additional cold-start emissions occur. It also calculates the fuel injection factor of the heavy-duty hybrid vehicle in a high-altitude, low-temperature environment based on the fuel injection quantity during cold starts and during thermally stable operation; calculates the low-temperature factor of the heavy-duty hybrid vehicle in a high-altitude, low-temperature environment based on the ambient temperature of the heavy-duty hybrid vehicle in both low-temperature and normal-temperature environments; and calculates the high-altitude low-temperature factor based on the exhaust temperature of the heavy-duty hybrid vehicle at specific stages and the cold-start exhaust temperature. This invention relates to the exhaust temperature factor of heavy-duty hybrid electric vehicles (HEVs) in low-temperature environments. It calculates the combined additional cold-start emissions of HEVs in high-altitude, low-temperature environments based on additional cold-start emissions, fuel injection factor, low-temperature factor, and exhaust temperature factor. By comprehensively considering the impact of fuel injection quantity, ambient temperature, and exhaust temperature on additional cold-start emissions in high-altitude, low-temperature environments, it more accurately reflects the vehicle's emissions under specific conditions, providing reliable data support for emission control and reduction strategies. Through accurate calculation of additional cold-start emissions, this invention helps improve the environmental adaptability of vehicles, ensuring effective emission control even in harsh environments. Attached Figure Description

[0054] Figure 1 This is a flowchart illustrating a method for calculating additional cold start emissions from automobiles in high-altitude, low-temperature environments, according to an embodiment of the present invention.

[0055] Figure 2 This is a schematic diagram of a system for calculating additional cold start emissions from a vehicle in a high-altitude, low-temperature environment, according to an embodiment of the present invention.

[0056] Figure 3 This is a schematic diagram of the structure of an electronic device according to an embodiment of the present invention. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0058] like Figure 1 As shown, one aspect of the present invention provides a method for calculating additional cold-start emissions from automobiles in high-altitude, low-temperature environments, comprising the following steps:

[0059] S1: Acquire engine operating parameter data, ambient temperature data, and instantaneous emission data of a heavy-duty hybrid vehicle in a high-altitude, low-temperature environment; engine operating parameters include engine coolant temperature, exhaust temperature, and fuel injection quantity; the instantaneous emission data includes instantaneous cold start emission data and instantaneous thermal stable operation emission data;

[0060] S2: Calculate the additional cold start emissions of heavy-duty hybrid electric vehicles in high-altitude and low-temperature environments based on the cold start emissions and thermal stability operation emissions of the heavy-duty hybrid electric vehicles in high-altitude and low-temperature environments, as well as the number of times additional cold start emissions occur.

[0061] S3: Calculate the fuel injection factor of a heavy-duty hybrid electric vehicle under high-altitude and low-temperature conditions based on the fuel injection quantity during cold start and during thermal stable operation.

[0062] S4: Calculate the low temperature factor of heavy-duty hybrid vehicles in low-temperature environments and normal-temperature environments based on the ambient temperature of heavy-duty hybrid vehicles in low-temperature environments.

[0063] S5: Calculate the exhaust temperature factor of a heavy-duty hybrid vehicle in a high-altitude, low-temperature environment based on the exhaust temperature and cold-start exhaust temperature of the heavy-duty hybrid vehicle at a specific stage.

[0064] S6: Calculate the combined additional cold start emissions of the heavy-duty hybrid vehicle under high-altitude and low-temperature conditions based on the additional cold start emissions of the heavy-duty hybrid vehicle under high-altitude and low-temperature conditions, the fuel injection factor, the low-temperature factor, and the exhaust temperature factor.

[0065] Furthermore, in step S1, the engine operating parameter data of the heavy-duty hybrid vehicle is obtained through the vehicle's sensor system; the engine coolant temperature and exhaust temperature are used to determine the vehicle's operating status, and the fuel injection quantity is directly related to the emission quantity.

[0066] The ambient temperature data is acquired by measuring the temperature of the environment in which the vehicle is located through temperature sensors outside the vehicle. Ambient temperature has a significant impact on cold start emissions, especially in high-altitude and low-temperature environments, where low temperatures increase fuel injection and emissions during cold starts.

[0067] The instantaneous emission data is acquired through the vehicle's emission monitoring system, collecting instantaneous emission data from heavy-duty hybrid vehicles; instantaneous emission data is key data for calculating cold start emissions and thermally stable operation emissions.

[0068] Furthermore, the additional cold start emissions of heavy-duty hybrid vehicles in the high-altitude low-temperature environment in step S2 are calculated using equation (1):

[0069]

[0070] in, This represents the average additional cold-start emissions of heavy-duty hybrid vehicles operating in high-altitude, low-temperature environments. This represents the average cold-start emissions of heavy-duty hybrid electric vehicles operating in high-altitude, low-temperature environments. is the average thermally stable operating emission of a heavy-duty hybrid electric vehicle in a high-altitude, low-temperature environment; T is the number of times a heavy-duty hybrid electric vehicle experiences additional cold-start emissions in a high-altitude, low-temperature environment.

[0071] Furthermore, the calculation of cold start emissions for heavy-duty hybrid vehicles in high-altitude, low-temperature environments in step S2 includes:

[0072] The cold start stage of a heavy-duty hybrid electric vehicle in a high-altitude, low-temperature environment is determined based on the engine coolant temperature. The cold start emissions of the heavy-duty hybrid electric vehicle in a high-altitude, low-temperature environment are calculated based on the time required for the cold start stage and the instantaneous cold start emissions. Specifically, when the engine coolant temperature does not exceed 70°C, it is considered to be in the cold start stage.

[0073] The cold start emissions of the heavy-duty hybrid vehicle are calculated using equation (2):

[0074]

[0075] in, tx represents the average cold-start emissions of a heavy-duty hybrid electric vehicle in a high-altitude, low-temperature environment; tx represents the time required for the engine coolant temperature of the heavy-duty hybrid electric vehicle to reach 70°C in a high-altitude, low-temperature environment; E 冷，i For the instantaneous cold start emissions of heavy-duty hybrid vehicles in high-altitude and low-temperature environments;

[0076] The calculation of thermal stability emissions of heavy-duty hybrid vehicles in high-altitude and low-temperature environments in step S2 includes:

[0077] Based on exhaust temperature, determine the different sub-stages and corresponding operating time ranges of thermal stability operation of heavy-duty hybrid vehicles in high-altitude and low-temperature environments.

[0078] The thermal stable operation emissions of heavy-duty hybrid electric vehicles in different sub-stages of thermal stable operation are calculated based on the instantaneous thermal stable operation emissions of different sub-stages of thermal stable operation and the corresponding operating time ranges in high-altitude low-temperature environments.

[0079] The thermally stable operating emissions of heavy-duty hybrid electric vehicles in different sub-stages are summed to calculate the thermally stable operating emissions of heavy-duty hybrid electric vehicles in high-altitude and low-temperature environments.

[0080] Specifically, when the engine coolant temperature is greater than 70°C, it is determined to be in the thermally stable operation stage; when the exhaust temperature reaches 200°C, it is a sub-stage; when the exhaust temperature is greater than 200°C, it is another sub-stage.

[0081] The thermally stable operating emissions of the heavy-duty hybrid vehicle are calculated using equation (3):

[0082]

[0083] in, The average thermally stable operating emissions of heavy-duty hybrid electric vehicles in high-altitude and low-temperature environments; The average thermally stable emission values ​​of heavy-duty hybrid vehicle engines operating at temperatures above 70°C and exhaust temperatures reaching 200°C in high-altitude and low-temperature environments. The average thermally stable emission values ​​of heavy-duty hybrid vehicle engines operating at temperatures above 70°C and above 200°C in high-altitude and low-temperature environments (generally, the aftertreatment system can only function normally when the exhaust temperature is above 200°C).

[0084] The thermally stable operating emissions of heavy-duty hybrid vehicle engines operating at temperatures above 70°C and above 200°C under high-altitude and low-temperature conditions are calculated using equation (4):

[0085]

[0086] Among them, t ET =200℃ is the time it takes for the exhaust temperature of a heavy-duty hybrid vehicle to reach 200℃ in a high-altitude, low-temperature environment; E a,i For heavy-duty hybrid vehicle engines operating under instantaneous thermal stability conditions where the coolant temperature is greater than 70°C and the exhaust temperature reaches 200°C in high-altitude and low-temperature environments;

[0087] The thermally stable operating emissions of heavy-duty hybrid vehicle engines operating at temperatures above 70°C and above 200°C under high-altitude and low-temperature conditions are calculated using equation (5):

[0088]

[0089] Among them, E b，i For heavy-duty hybrid vehicle engines operating under conditions of high altitude and low temperature, where the engine coolant temperature exceeds 70℃ and the exhaust temperature exceeds 200℃, the instantaneous thermally stable emission is required. n This refers to the time when the thermal stability operation of a heavy-duty hybrid vehicle ends in a high-altitude, low-temperature environment.

[0090] Furthermore, in step S3, the fuel injection factor of the heavy-duty hybrid vehicle under high-altitude low-temperature conditions is calculated using equation (6):

[0091]

[0092] Where f is the fuel injection factor of a heavy-duty hybrid vehicle operating in high-altitude, low-temperature environments, F 冷 This refers to the fuel injection quantity during cold start of a heavy-duty hybrid vehicle in high-altitude, low-temperature environments; F 热 This refers to the fuel injection quantity of a heavy-duty hybrid vehicle during thermally stable operation in high-altitude and low-temperature environments. The fuel injection factor reflects the increase in fuel injection quantity during cold starts relative to that during thermally stable operation, and is used to comprehensively consider the impact of fuel injection quantity on emissions.

[0093] Furthermore, in step S4, the low-temperature factor of the heavy-duty hybrid vehicle under high-altitude low-temperature conditions is calculated using equation (7):

[0094]

[0095] Where w is the low-temperature factor of a heavy-duty hybrid vehicle in a high-altitude, low-temperature environment, W 低 The ambient temperature for heavy-duty hybrid vehicles in low-temperature environments; W 常 The ambient temperature is the ambient temperature of a heavy-duty hybrid vehicle under normal temperature conditions; the low temperature environment refers to an ambient temperature of (-7±5)℃; the normal temperature environment refers to an ambient temperature of (23±5)℃; the low temperature factor reflects the degree of change of ambient temperature under low temperature conditions relative to ambient temperature conditions, and is used to comprehensively consider the impact of ambient temperature on emissions.

[0096] Furthermore, in step S5, the exhaust temperature factor of the heavy-duty hybrid vehicle under high-altitude low-temperature conditions is calculated using equation (8):

[0097]

[0098] Where et is the exhaust temperature factor (ET) of a heavy-duty hybrid vehicle operating in low-temperature, high-altitude environments; 冷 The cold start exhaust temperature (ET) of a heavy-duty hybrid vehicle operating in low-temperature, high-altitude environments; kThis indicates the exhaust temperature at a specific stage; the specific stage includes the cold start stage of a heavy-duty hybrid vehicle in a high-altitude and low-temperature environment, the thermally stable operation stage with engine coolant temperature greater than 70°C and exhaust temperature reaching 200°C, or the thermally stable operation stage with engine coolant temperature greater than 70°C and exhaust temperature greater than 200°C.

[0099] A higher exhaust temperature factor (et) indicates a higher exhaust temperature at a specific stage compared to the cold start stage. This can affect the performance of the aftertreatment system, thereby impacting emissions. Calculating this factor allows for a better understanding and control of the emissions behavior of heavy-duty hybrid vehicles under different operating conditions.

[0100] Furthermore, the additional cold-start combined emissions of the heavy-duty hybrid vehicle in the high-altitude low-temperature environment described in step S6 are calculated using equation (9):

[0101]

[0102] in, This represents the average combined emissions from additional cold starts of heavy-duty hybrid vehicles operating in high-altitude, low-temperature environments.

[0103] like Figure 2 As shown, a second aspect of the present invention provides a system for calculating additional cold-start emissions from automobiles in high-altitude, low-temperature environments, for implementing the above-mentioned design method, comprising:

[0104] The data acquisition module is used to acquire engine operating parameter data, ambient temperature data, and instantaneous emission data of heavy-duty hybrid vehicles in high-altitude and low-temperature environments. The engine operating parameters include engine coolant temperature, exhaust temperature, and fuel injection quantity. The instantaneous emission data includes instantaneous cold start emission data and instantaneous thermal stable operation emission data.

[0105] The additional cold start emission calculation module is used to calculate the additional cold start emission of heavy-duty hybrid vehicles in high-altitude and low-temperature environments based on the cold start emission and thermal stability operation emission of the heavy-duty hybrid vehicles in high-altitude and low-temperature environments, as well as the number of times additional cold start emission occurs.

[0106] The fuel injection factor calculation module is used to calculate the fuel injection factor of a heavy-duty hybrid vehicle under high-altitude and low-temperature conditions based on the fuel injection quantity during cold start and during thermal stable operation.

[0107] The low-temperature factor calculation module is used to calculate the low-temperature factor of heavy-duty hybrid vehicles in high-altitude low-temperature environments based on the ambient temperature in low-temperature environments and ambient temperature in normal environments.

[0108] The exhaust temperature factor calculation module is used to calculate the exhaust temperature factor of a heavy-duty hybrid vehicle in a high-altitude and low-temperature environment based on the exhaust temperature and cold start exhaust temperature of the heavy-duty hybrid vehicle at a specific stage.

[0109] The integrated emissions calculation module is used to calculate the additional cold start integrated emissions of the heavy-duty hybrid vehicle under high-altitude and low-temperature conditions based on the additional cold start emissions of the heavy-duty hybrid vehicle under high-altitude and low-temperature conditions, the fuel injection factor, the low-temperature factor, and the exhaust temperature factor.

[0110] Furthermore, the data acquisition module includes an engine operating parameter acquisition submodule, an ambient temperature acquisition submodule, and an instantaneous emission data acquisition submodule. The engine operating parameter acquisition submodule is responsible for acquiring engine operating parameter data such as engine coolant temperature, exhaust temperature, and fuel injection quantity. The ambient temperature acquisition submodule is used to measure and acquire the temperature value of the environment in which the vehicle is located through external temperature sensors. The instantaneous emission data acquisition submodule is used to acquire instantaneous emission data of the heavy-duty hybrid vehicle through the vehicle's emission monitoring system, including instantaneous cold start emission data and instantaneous thermal stability operation emission data.

[0111] Furthermore, the additional cold start emission calculation module includes a cold start emission calculation submodule, a thermally stable operation emission calculation submodule, and an additional cold start emission calculation submodule;

[0112] The cold start emission calculation submodule is used to determine the cold start stage of the heavy-duty hybrid vehicle under high altitude and low temperature conditions based on the engine coolant temperature, and to calculate the cold start emission of the heavy-duty hybrid vehicle under high altitude and low temperature conditions based on the time required for the cold start stage of the heavy-duty hybrid vehicle and the instantaneous cold start emission.

[0113] The thermally stable operation emission calculation submodule is used to determine the different sub-stages and corresponding operating time ranges of the thermally stable operation of the heavy-duty hybrid vehicle under high-altitude and low-temperature conditions based on the exhaust temperature; calculate the thermally stable operation emissions of the heavy-duty hybrid vehicle under different sub-stages based on the instantaneous thermally stable operation emissions and corresponding operating time ranges of the different sub-stages of the thermally stable operation of the heavy-duty hybrid vehicle under high-altitude and low-temperature conditions; sum the thermally stable operation emissions of the heavy-duty hybrid vehicle under different sub-stages to calculate the thermally stable operation emissions of the heavy-duty hybrid vehicle under high-altitude and low-temperature conditions.

[0114] The additional cold start emission calculation submodule is used to calculate additional cold start emissions based on the cold start emissions, thermal stability operation emissions, and additional cold start emission times of heavy-duty hybrid vehicles in high-altitude and low-temperature environments.

[0115] Furthermore, the additional cold-start emissions of the heavy-duty hybrid vehicle in the high-altitude low-temperature environment are calculated using equation (1):

[0116]

[0117] in, This represents the average additional cold-start emissions of heavy-duty hybrid vehicles operating in high-altitude, low-temperature environments. This represents the average cold-start emissions of heavy-duty hybrid electric vehicles operating in high-altitude, low-temperature environments. is the average thermally stable operating emission of a heavy-duty hybrid electric vehicle in a high-altitude, low-temperature environment; T is the number of times a heavy-duty hybrid electric vehicle experiences additional cold-start emissions in a high-altitude, low-temperature environment.

[0118] The cold start emissions of the heavy-duty hybrid vehicle are calculated using equation (2):

[0119]

[0120] in, This represents the average cold-start emissions of heavy-duty hybrid electric vehicles operating in high-altitude, low-temperature environments; t 冷 E represents the time required for the engine coolant temperature of a heavy-duty hybrid vehicle to reach 70°C in high-altitude, low-temperature environments. 冷,i For the instantaneous cold start emissions of heavy-duty hybrid vehicles in high-altitude and low-temperature environments;

[0121] The thermally stable operating emissions of the heavy-duty hybrid vehicle are calculated using equation (3):

[0122]

[0123] in, The average thermally stable operating emissions of heavy-duty hybrid electric vehicles in high-altitude and low-temperature environments; The average thermally stable emission values ​​of heavy-duty hybrid vehicle engines operating at temperatures above 70°C and exhaust temperatures reaching 200°C in high-altitude and low-temperature environments. The average thermally stable emission values ​​of heavy-duty hybrid vehicle engines operating at temperatures above 70°C and above 200°C in high-altitude and low-temperature environments (generally, the aftertreatment system can only function normally when the exhaust temperature is above 200°C).

[0124] The thermally stable operating emissions of heavy-duty hybrid vehicle engines operating at temperatures above 70°C and above 200°C under high-altitude and low-temperature conditions are calculated using equation (4):

[0125]

[0126] Among them, t ET =200℃ is the time it takes for the exhaust temperature of a heavy-duty hybrid vehicle to reach 200℃ in a high-altitude, low-temperature environment; E a,iFor heavy-duty hybrid vehicle engines operating under instantaneous thermal stability conditions where the coolant temperature is greater than 70°C and the exhaust temperature reaches 200°C in high-altitude and low-temperature environments;

[0127] The thermally stable operating emissions of heavy-duty hybrid vehicle engines operating at temperatures above 70°C and above 200°C under high-altitude and low-temperature conditions are calculated using equation (5):

[0128]

[0129] Among them, E b，i For heavy-duty hybrid vehicle engines operating under conditions of high altitude and low temperature, where the engine coolant temperature exceeds 70℃ and the exhaust temperature exceeds 200℃, the instantaneous thermally stable emission is required. n This refers to the time when the thermal stability operation of a heavy-duty hybrid vehicle ends in a high-altitude, low-temperature environment.

[0130] Furthermore, the fuel injection factor of a heavy-duty hybrid vehicle in a high-altitude, low-temperature environment is calculated using equation (6):

[0131]

[0132] Where f is the fuel injection factor of a heavy-duty hybrid vehicle operating in high-altitude, low-temperature environments, F 冷 This refers to the fuel injection quantity during cold start of a heavy-duty hybrid vehicle in high-altitude, low-temperature environments; F 热 This refers to the fuel injection quantity of a heavy-duty hybrid vehicle during thermally stable operation in high-altitude and low-temperature environments. The fuel injection factor reflects the increase in fuel injection quantity during cold starts relative to that during thermally stable operation, and is used to comprehensively consider the impact of fuel injection quantity on emissions.

[0133] Furthermore, the low-temperature factor of a heavy-duty hybrid vehicle in a high-altitude, low-temperature environment is calculated using equation (7):

[0134]

[0135] Where w is the low-temperature factor of a heavy-duty hybrid vehicle in a high-altitude, low-temperature environment, W 低 The ambient temperature for heavy-duty hybrid vehicles in low-temperature environments; W 常 The ambient temperature is the ambient temperature of a heavy-duty hybrid vehicle under normal temperature conditions; the low temperature factor reflects the degree of change in ambient temperature under low temperature conditions relative to ambient temperature under normal temperature conditions, and is used to comprehensively consider the impact of ambient temperature on emissions.

[0136] Furthermore, the exhaust temperature factor of a heavy-duty hybrid vehicle in a high-altitude, low-temperature environment is calculated using equation (8):

[0137]

[0138] Where et is the exhaust temperature factor (ET) of a heavy-duty hybrid vehicle operating in low-temperature, high-altitude environments; 冷 The cold start exhaust temperature (ET) of a heavy-duty hybrid vehicle operating in low-temperature, high-altitude environments; k This indicates the exhaust temperature at a specific stage; the specific stage includes the cold start stage of a heavy-duty hybrid vehicle in a high-altitude and low-temperature environment, the thermally stable operation stage with engine coolant temperature greater than 70°C and exhaust temperature reaching 200°C, or the thermally stable operation stage with engine coolant temperature greater than 70°C and exhaust temperature greater than 200°C.

[0139] Furthermore, the additional cold-start combined emissions of heavy-duty hybrid vehicles in high-altitude, low-temperature environments are calculated using equation (9):

[0140]

[0141] in, This represents the average combined emissions from additional cold starts of heavy-duty hybrid vehicles operating in high-altitude, low-temperature environments.

[0142] It should be noted that the vehicle additional cold start emission calculation system provided in this embodiment under high altitude and low temperature conditions can be a computer program (including program code) running on a computer device. For example, the vehicle additional cold start emission calculation system under high altitude and low temperature conditions is an application software. The vehicle additional cold start emission calculation system under high altitude and low temperature conditions can be used to execute the corresponding steps in the above-mentioned method provided in the embodiments of this application.

[0143] In some feasible implementations, the vehicle additional cold start emission calculation system provided in this embodiment under high-altitude and low-temperature conditions can be implemented using a combination of hardware and software. As an example, the vehicle additional cold start emission calculation system under high-altitude and low-temperature conditions provided in this application embodiment can be a processor in the form of a hardware decoding processor, which is programmed to execute the vehicle additional cold start emission calculation method under high-altitude and low-temperature conditions provided in this application embodiment. For example, the processor in the form of a hardware decoding processor can adopt one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), programmable logic devices (PLDs), complex programmable logic devices (CPLDs), field-programmable gate arrays (FPGAs), or other electronic components.

[0144] In some feasible implementations, the vehicle additional cold start emission calculation system provided in this embodiment can be implemented in software. It can be software in the form of programs and plug-ins, and includes a series of modules to implement the vehicle additional cold start emission calculation method in high-altitude and low-temperature environments provided in this embodiment of the invention.

[0145] A third aspect of the present invention also provides an electronic device, Figure 3 This is a schematic diagram of the electronic device in this embodiment, as shown below. Figure 3 As shown, the electronic device 1000 in this embodiment may include: a processor 1001, a network interface 1004, and a memory 1005. Furthermore, the electronic device 1000 may also include: a user interface 1003, and at least one communication bus 1002. The communication bus 1002 is used to implement communication between these components. The user interface 1003 may include a display screen and a keyboard; optionally, the user interface 1003 may also include a standard wired interface or a wireless interface. The network interface 1004 may optionally include a standard wired interface or a wireless interface (such as a Wi-Fi interface). The memory 1005 may be a high-speed RAM memory or a non-volatile memory, such as at least one disk storage device. Optionally, the memory 1005 may also be at least one storage device located remotely from the aforementioned processor 1001. Figure 3 As shown, the memory 1005, which is a computer-readable storage medium, may include an operating system, a network communication module, a user interface module, and a device control application.

[0146] like Figure 3 In the electronic device 1000 shown, the network interface 1004 provides network communication functions; the user interface 1003 is mainly used to provide an input interface for users; and the processor 1001 can be used to call the device control application stored in the memory 1005 to implement each step of the above-mentioned method for calculating additional cold start emissions of automobiles in high-altitude and low-temperature environments.

[0147] It should be understood that in some feasible implementations, the processor 1001 described above may be a central processing unit (CPU), which may also be other general-purpose processors, DSPs, ASICs, FPGAs, or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor. The memory may include read-only memory and random access memory, and provides instructions and data to the processor. A portion of the memory may also include non-volatile random access memory. For example, the memory may also store device type information.

[0148] In specific implementation, the aforementioned electronic device 1000 can perform the above-described actions through its built-in functional modules. Figure 1 The implementation methods provided for each step are detailed in the above-mentioned implementation methods, and will not be repeated here.

[0149] This application also provides a computer-readable storage medium storing a computer program that is executed by a processor to implement... Figure 1 The methods provided in each step are detailed in the implementation methods provided in the above steps, and will not be repeated here.

[0150] Any references to memory, storage, database, or other media used in the embodiments provided in this application may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM), etc.

[0151] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for calculating additional cold-start emissions from automobiles in high-altitude, low-temperature environments, characterized in that, Includes the following steps: S1: Acquire engine operating parameter data, ambient temperature data, and instantaneous emission data of a heavy-duty hybrid vehicle in a high-altitude, low-temperature environment; engine operating parameters include engine coolant temperature, exhaust temperature, and fuel injection quantity; the instantaneous emission data includes instantaneous cold start emission data and instantaneous thermal stable operation emission data; S2: Calculate the additional cold start emissions of heavy-duty hybrid electric vehicles in high-altitude and low-temperature environments based on the cold start emissions and thermal stability operation emissions of the heavy-duty hybrid electric vehicles in high-altitude and low-temperature environments, as well as the number of times additional cold start emissions occur. S3: Calculate the fuel injection factor of a heavy-duty hybrid electric vehicle under high-altitude and low-temperature conditions based on the fuel injection quantity during cold start and during thermal stable operation. S4: Calculate the low temperature factor of heavy-duty hybrid vehicles in low-temperature environments and normal-temperature environments based on the ambient temperature of heavy-duty hybrid vehicles in low-temperature environments. S5: Calculate the exhaust temperature factor of a heavy-duty hybrid vehicle in a high-altitude, low-temperature environment based on the exhaust temperature and cold-start exhaust temperature of the heavy-duty hybrid vehicle at a specific stage. S6: Calculate the combined additional cold start emissions of the heavy-duty hybrid vehicle under high-altitude and low-temperature conditions based on the additional cold start emissions of the heavy-duty hybrid vehicle under high-altitude and low-temperature conditions, the fuel injection factor, the low-temperature factor, and the exhaust temperature factor.

2. The method for calculating additional cold start emissions of automobiles under high-altitude and low-temperature conditions according to claim 1, characterized in that: The calculation of cold start emissions for heavy-duty hybrid vehicles in high-altitude, low-temperature environments in step S2 includes: The cold start stage of a heavy-duty hybrid electric vehicle in a high-altitude, low-temperature environment is determined based on the engine coolant temperature. The cold start emissions of the heavy-duty hybrid electric vehicle in a high-altitude, low-temperature environment are calculated based on the time required for the cold start stage and the instantaneous cold start emissions. When the engine coolant temperature does not exceed 70°C, it is considered to be in the cold start stage; In step S2, the additional cold start emissions of heavy-duty hybrid vehicles in high-altitude low-temperature environments are calculated using equation (1): in, This represents the average additional cold-start emissions of heavy-duty hybrid vehicles operating in high-altitude, low-temperature environments. This represents the average cold-start emissions of heavy-duty hybrid electric vehicles operating in high-altitude, low-temperature environments. is the average thermally stable operating emission of a heavy-duty hybrid electric vehicle in a high-altitude, low-temperature environment; T is the number of times a heavy-duty hybrid electric vehicle experiences additional cold-start emissions in a high-altitude, low-temperature environment.

3. The method for calculating additional cold start emissions of automobiles under high-altitude and low-temperature conditions according to claim 2, characterized in that: The calculation of thermal stability emissions of heavy-duty hybrid vehicles in high-altitude and low-temperature environments in step S2 includes: Based on exhaust temperature, determine the different sub-stages and corresponding operating time ranges of thermal stability operation of heavy-duty hybrid vehicles in high-altitude and low-temperature environments. The thermal stable operation emissions of heavy-duty hybrid electric vehicles in different sub-stages of thermal stable operation are calculated based on the instantaneous thermal stable operation emissions of different sub-stages of thermal stable operation and the corresponding operating time ranges in high-altitude low-temperature environments. The thermally stable operating emissions of heavy-duty hybrid electric vehicles in different sub-stages are summed to calculate the thermally stable operating emissions of heavy-duty hybrid electric vehicles in high-altitude and low-temperature environments. When the engine coolant temperature is greater than 70°C, it is considered to be in the thermally stable operation stage; when the exhaust temperature reaches 200°C, it is a sub-stage; when the exhaust temperature is greater than 200°C, it is another sub-stage.

4. The method for calculating additional cold start emissions of automobiles under high-altitude and low-temperature conditions according to claim 3, characterized in that: The thermally stable operating emissions of the heavy-duty hybrid vehicle are calculated using equation (3): in, The average thermally stable operating emissions of heavy-duty hybrid electric vehicles in high-altitude and low-temperature environments; The average thermally stable emission values ​​of heavy-duty hybrid vehicle engines operating at temperatures above 70°C and exhaust temperatures reaching 200°C in high-altitude and low-temperature environments. The average thermally stable emission values ​​for heavy-duty hybrid vehicle engines operating at temperatures above 70°C and above 200°C in high-altitude, low-temperature environments.

5. The method for calculating additional cold start emissions of automobiles under high-altitude and low-temperature conditions according to claim 4, characterized in that: The thermally stable operating emissions of heavy-duty hybrid vehicle engines operating at temperatures above 70°C and above 200°C under high-altitude and low-temperature conditions are calculated using equation (4): Among them, tE T =200℃ is the time it takes for the exhaust temperature of a heavy-duty hybrid vehicle to reach 200℃ in a high-altitude, low-temperature environment; E a，i For heavy-duty hybrid vehicle engines operating under conditions of high altitude and low temperature, where the engine coolant temperature exceeds 70°C and the exhaust temperature reaches 200°C, instantaneous thermally stable emissions are required. 冷 The time required for the engine coolant temperature of a heavy-duty hybrid vehicle to reach 70°C in a high-altitude, low-temperature environment. The thermally stable operating emissions of heavy-duty hybrid vehicle engines operating at temperatures above 70°C and above 200°C under high-altitude and low-temperature conditions are calculated using equation (5): Among them, E b，i For heavy-duty hybrid vehicle engines operating under conditions of high altitude and low temperature, where the engine coolant temperature exceeds 70℃ and the exhaust temperature exceeds 200℃, the instantaneous thermally stable emission is required. n This refers to the time when the thermal stability operation of a heavy-duty hybrid vehicle ends in a high-altitude, low-temperature environment.

6. A method for calculating additional cold start emissions from automobiles in high-altitude, low-temperature environments according to any one of claims 1-5, characterized in that: In step S3, the fuel injection factor of the heavy-duty hybrid vehicle under high-altitude and low-temperature conditions is calculated using equation (6): Where f is the fuel injection factor of a heavy-duty hybrid vehicle operating in high-altitude, low-temperature environments, F 冷 This refers to the fuel injection quantity during cold start of a heavy-duty hybrid vehicle in high-altitude, low-temperature environments; F 热 This refers to the fuel injection quantity for heavy-duty hybrid vehicles operating under thermal stability conditions in high-altitude and low-temperature environments.

7. A method for calculating additional cold start emissions from automobiles in high-altitude, low-temperature environments according to any one of claims 1-5, characterized in that: In step S4, the low-temperature factor of the heavy-duty hybrid vehicle in the high-altitude low-temperature environment is calculated using equation (7): Where W is the low-temperature factor of heavy-duty hybrid vehicles in high-altitude, low-temperature environments, W 低 The ambient temperature for heavy-duty hybrid vehicles in low-temperature environments; W 常 The ambient temperature for heavy-duty hybrid vehicles under normal temperature conditions.

8. A method for calculating additional cold start emissions from automobiles in high-altitude, low-temperature environments according to any one of claims 1-5, characterized in that: In step S5, the exhaust temperature factor of the heavy-duty hybrid vehicle under high-altitude and low-temperature conditions is calculated using equation (8): Where et is the exhaust temperature factor (ET) of a heavy-duty hybrid vehicle operating in low-temperature, high-altitude environments; 冷 The cold start exhaust temperature (ET) of a heavy-duty hybrid vehicle operating in low-temperature, high-altitude environments; k This indicates the exhaust temperature at a specific stage; the specific stage includes the cold start stage of a heavy-duty hybrid vehicle in a high-altitude and low-temperature environment, the thermally stable operation stage with engine coolant temperature greater than 70°C and exhaust temperature reaching 200°C, or the thermally stable operation stage with engine coolant temperature greater than 70°C and exhaust temperature greater than 200°C.

9. A method for calculating additional cold start emissions of automobiles under high-altitude and low-temperature conditions according to any one of claims 1-5, characterized in that: The additional cold-start combined emissions of heavy-duty hybrid vehicles in high-altitude low-temperature environments described in step S6 are calculated using equation (9): in, This represents the average combined emissions from additional cold starts of heavy-duty hybrid vehicles operating in high-altitude, low-temperature environments.

10. A system for calculating additional cold start emissions from automobiles in high-altitude, low-temperature environments, characterized in that, The method for calculating additional cold start emissions of automobiles in high-altitude and low-temperature environments as described in any one of claims 1-9 includes: The data acquisition module is used to acquire engine operating parameter data, ambient temperature data, and instantaneous emission data of heavy-duty hybrid vehicles in high-altitude and low-temperature environments. The engine operating parameters include engine coolant temperature, exhaust temperature, and fuel injection quantity. The instantaneous emission data includes instantaneous cold start emission data and instantaneous thermal stable operation emission data. The additional cold start emission calculation module is used to calculate the additional cold start emission of heavy-duty hybrid vehicles in high-altitude and low-temperature environments based on the cold start emission and thermal stability operation emission of the heavy-duty hybrid vehicles in high-altitude and low-temperature environments, as well as the number of times additional cold start emission occurs. The fuel injection factor calculation module is used to calculate the fuel injection factor of a heavy-duty hybrid vehicle under high-altitude and low-temperature conditions based on the fuel injection quantity during cold start and during thermal stable operation. The low-temperature factor calculation module is used to calculate the low-temperature factor of heavy-duty hybrid vehicles in high-altitude low-temperature environments based on the ambient temperature in low-temperature environments and ambient temperature in normal environments. The exhaust temperature factor calculation module is used to calculate the exhaust temperature factor of a heavy-duty hybrid vehicle in a high-altitude and low-temperature environment based on the exhaust temperature and cold start exhaust temperature of the heavy-duty hybrid vehicle at a specific stage. The integrated emissions calculation module is used to calculate the additional cold start integrated emissions of the heavy-duty hybrid vehicle under high-altitude and low-temperature conditions based on the additional cold start emissions of the heavy-duty hybrid vehicle under high-altitude and low-temperature conditions, the fuel injection factor, the low-temperature factor, and the exhaust temperature factor.

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