CN-122014442-A - Natural gas extreme working condition catalyst inlet temperature lifting device and control method

CN122014442ACN 122014442 ACN122014442 ACN 122014442ACN-122014442-A

Abstract

The invention discloses a control method for improving inlet temperature of a catalyst under extreme working conditions of natural gas, relates to an internal combustion engine, and solves the technical problems that the existing seven-natural-gas engine for heavy duty countries has lean air intake, insufficient combustion and difficult catalyst inlet temperature reaching standards under extreme working conditions. The control method comprises the steps of arranging an electric supercharger between an air filter and a supercharger, arranging an exhaust throttle valve between a catalyst and the supercharger, judging an engine working condition according to collected inlet pressure, inlet temperature of the catalyst, rotating speed and real-time altitude, and triggering a cooperative control temperature raising strategy to control the electric supercharger and the exhaust throttle valve to raise inlet temperature of the catalyst when the engine working condition is judged to be a high-altitude and small-inlet-pressure working condition. The invention also discloses a natural gas extreme condition catalyst inlet temperature lifting control system. The invention improves the temperature raising efficiency and stability, and is suitable for the long-distance operation requirement of the heavy natural gas engine.

Inventors

TAN ZONGHUI
CHEN HUAN
NING DEZHONG
LIN TIEJIAN
WANG HUI
WEI ZUANGUO
SHENG LI
HE HUIXIN

Assignees

广西玉柴机器股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260331

Claims (10)

1. The control method is characterized in that an electric booster (4) is arranged between an air filter (2) and a booster (9), an exhaust throttle valve (8) is arranged between a catalyst (6) and the booster (9), the intake pressure, the catalyst inlet temperature, the rotating speed and the real-time elevation of an engine are collected, the engine working condition is judged according to the intake pressure, the catalyst inlet temperature, the rotating speed and the real-time elevation, and when the engine working condition is judged to be a high-elevation and small-intake-pressure working condition, a cooperative control temperature raising strategy is triggered to raise the catalyst inlet temperature; Acquiring the running state of the electric supercharger (4) and the running state of the exhaust throttle valve (8) when the cooperative control temperature raising strategy is executed, and triggering a standby temperature raising strategy when the running state of the electric supercharger (4) or the running state of the exhaust throttle valve (8) is in a fault state; and acquiring the target temperature of the inlet of the catalyst after executing the cooperative control temperature raising strategy, and triggering a closed-loop control strategy according to the target temperature of the inlet of the catalyst so as to adjust the cooperative control temperature raising strategy.
2. The method for controlling inlet temperature elevation of a natural gas extreme catalyst according to claim 1, wherein the cooperative control temperature elevation strategy is that, Controlling the electric supercharger (4) to raise the intake air pressure to a preset first intake air pressure; an air inlet heating module is arranged at an air outlet of the electric supercharger (4), and the air inlet heating module is controlled to increase the air inlet temperature to a preset first air inlet temperature; Setting a first ignition advance angle retardation value, retarding a current ignition advance angle according to the first ignition advance angle retardation value, completely closing an EGR valve, setting a first air-fuel ratio and a second air-fuel ratio, injecting an inner cylinder core area according to the first air-fuel ratio, and injecting an inner cylinder edge area according to the second air-fuel ratio; the opening degree of the exhaust throttle valve (8) is set to a preset first opening degree.
3. The method for controlling inlet temperature elevation of a natural gas extreme catalyst according to claim 2, wherein the method for obtaining the target inlet temperature of the catalyst after executing the cooperative temperature elevation control strategy comprises the steps of, The method comprises the steps of obtaining the exhaust specific heat capacity, the pipeline length from a throttle valve outlet to a catalyst inlet, the pipeline heat dissipation coefficient, the environment temperature of an engine, the exhaust throttle valve outlet exhaust pressure and the turbine outlet exhaust pressure, calculating the exhaust throttle valve opening according to the exhaust throttle valve outlet exhaust pressure and the turbine outlet exhaust pressure, obtaining the natural gas combustion heat release amount, the fixed pressure specific heat capacity of EGR exhaust gas, the temperature when the EGR exhaust gas is introduced, the fixed pressure specific heat capacity of fresh air, the EGR exhaust gas mass flow, the fresh air temperature, the fixed pressure specific heat capacity of turbine outlet exhaust gas, the total exhaust mass flow, the turbine output work, the fixed pressure specific heat capacity of fresh air and the fresh air mass flow in unit time, and calculating the supercharger outlet temperature according to the exhaust throttle valve opening, the temperature of the heater outlet, the pipeline heat dissipation coefficient, the fixed pressure specific heat capacity of the turbine outlet exhaust gas, the engine inlet specific heat capacity and the target engine inlet temperature according to the natural gas combustion heat release amount, the fixed pressure specific heat capacity of the EGR exhaust gas, the EGR exhaust gas mass flow, the fresh air fixed pressure specific heat capacity, the fresh air temperature of the turbine outlet air, the turbine outlet specific heat capacity and the fresh air mass flow.
4. A natural gas extreme catalyst inlet temperature increase control method according to claim 3, wherein the catalyst inlet target temperature is calculated by the following expression, ; Wherein, T cat,in is the inlet temperature of the catalyst, T turb,out is the outlet temperature of the supercharger, θ is the opening of the exhaust throttle valve, K is the heat dissipation coefficient of the pipeline, L is the length of the pipeline from the outlet of the throttle valve to the inlet of the catalyst, T amb is the ambient temperature where the engine is located, and K is the specific heat capacity of the exhaust.
5. The method for controlling inlet temperature elevation of natural gas extreme catalyst according to claim 3, wherein the calculation expression of the opening degree of the exhaust throttle valve is, ; Where P throttle,out is the exhaust throttle outlet exhaust pressure, P turb,out is the turbine outlet exhaust pressure, and θ is the exhaust throttle opening.
6. A natural gas extreme catalyst inlet temperature boost control method according to claim 3, wherein the supercharger outlet temperature is calculated as follows, ; Wherein, T turb,out is the outlet temperature of the supercharger, Q comb is the combustion heat release amount of natural gas in unit time, C p,egr is the constant pressure specific heat capacity of EGR waste gas, T egr is the temperature when the EGR waste gas is introduced, C p,air is the constant pressure specific heat capacity of fresh air, m egr is the mass flow of EGR waste gas, T air is the fresh air inlet temperature, C p,exh is the constant pressure specific heat capacity of turbine outlet exhaust, m exh is the total exhaust mass flow, W turb is the turbine output work, C p,air is the constant pressure specific heat capacity of fresh air, and m air is the mass flow of fresh air.
7. The method of claim 2, wherein the backup ramp Wen Ce is configured to calibrate a second spark advance retard based on the engine operating condition, retard the current spark advance based on the first spark advance retard increasing to the second spark advance retard, set a third air-fuel ratio and a fourth air-fuel ratio, ramp the first air-fuel ratio to the third air-fuel ratio, and ramp the second air-fuel ratio to the fourth air-fuel ratio.
8. The method for controlling inlet temperature elevation of a natural gas extreme condition catalyst according to claim 2, wherein the closed loop control strategy is to obtain a light-off temperature of the catalyst, calibrate a first temperature threshold and a second temperature threshold according to the light-off temperature of the catalyst, and strengthen the cooperative control temperature elevation strategy when the inlet temperature of the catalyst is less than the first temperature threshold; When the catalyst inlet temperature is greater than or equal to a first temperature threshold and less than a second temperature threshold, maintaining the cooperative control temperature increasing strategy; and when the inlet temperature of the catalyst is greater than or equal to a second temperature threshold value, carrying out load reduction durable protection.
9. The method for controlling the inlet temperature elevation of a natural gas extreme condition catalyst according to claim 1, wherein the engine condition is judged according to the intake pressure, the catalyst inlet temperature, the rotation speed and the real-time altitude, And setting an altitude threshold value and an air inlet pressure threshold value, and judging that the engine working condition is a high-altitude and small-air inlet pressure working condition when the air inlet pressure is smaller than the air inlet pressure threshold value and the real-time altitude is larger than the altitude threshold value.
10. A control device for improving the inlet temperature of a catalyst under the extreme working condition of natural gas is characterized in that the control device comprises, An electric supercharger (4) installed between the air filter (2) and the supercharger (9) for elevating the intake air pressure; The air inlet heating module is arranged at an air outlet of the electric supercharger (4) and is used for increasing the air inlet temperature; an exhaust throttle valve (8) installed between the catalyst (6) and the supercharger (9) for controlling exhaust back pressure; The multi-parameter signal acquisition module is used for acquiring the air inlet pressure of the engine, the inlet temperature of the catalyst, the rotating speed and the real-time altitude of the engine and outputting corresponding air inlet pressure signals, catalyst inlet temperature signals, rotating speed signals and altitude signals; An ECU (5) for receiving the intake pressure signal, the catalyst inlet temperature signal, the rotation speed signal and the altitude signal and applying a natural gas extreme condition catalyst inlet temperature elevation control method according to any one of the preceding claims 1-9 to control the intake heating module, the electric supercharger (4) and the exhaust throttle valve (8) to elevate the catalyst inlet temperature in accordance with the intake pressure of the engine, the catalyst inlet temperature, the rotation speed and the real-time altitude at which the engine is located.

Description

Natural gas extreme working condition catalyst inlet temperature lifting device and control method Technical Field The invention relates to an internal combustion engine, in particular to a device for improving the inlet temperature of a natural gas extreme working condition catalyst and a control method. Background With the release of the double-carbon targets, the transportation industry is taken as an industry with relatively large carbon emission contribution and plays a critical role in emission reduction contribution. In 2018, the national six-emission regulation of the heavy-duty engine falls to the ground, and along with the approximation of the internal combustion engine technology and the double-carbon target node, the national seven-emission regulation of the heavy-duty engine is about to be real-time, and technical pre-research is carried out for each internal combustion engine manufacturer achieving the national seven-emission standard, so that researches are carried out on key aspects such as emission control, catalyst thermal management and the like. The temperature of the catalyst plays a key role in the catalytic efficiency of the catalyst, and under the national seventh emission index with increasingly strict emission requirements, the temperature thermal management of the catalyst is also a key ring, and particularly under the working conditions of low engine tail exhaust temperature such as idling, small load and the like, how to adapt to the high-altitude extreme working conditions, meet the emission requirements and are also key subjects needing to be subjected to key research. Disclosure of Invention The invention aims to solve the technical problems of lean air intake, insufficient combustion and difficult achievement of the inlet temperature of a catalyst under extreme working conditions of a heavy national seven-natural-gas engine. The invention relates to a control method for improving inlet temperature of a catalyst under extreme working conditions of natural gas, which comprises the steps of arranging an electric booster between an air filter and the booster, arranging an exhaust throttle valve between the catalyst and the booster, collecting inlet pressure, inlet temperature and rotating speed of an engine and real-time elevation of the inlet throttle valve, judging working conditions of the engine according to the inlet pressure, the inlet temperature and the rotating speed of the catalyst and the real-time elevation, and triggering a cooperative control temperature improving strategy to improve the inlet temperature of the catalyst when the working conditions of the engine are judged to be high-elevation and small-inlet pressure working conditions; acquiring the running state of the electric supercharger and the running state of the exhaust throttle valve when the cooperative control temperature raising strategy is executed, and triggering a standby temperature raising strategy when the running state of the electric supercharger or the running state of the exhaust throttle valve is in a fault state; and acquiring the target temperature of the inlet of the catalyst after executing the cooperative control temperature raising strategy, and triggering a closed-loop control strategy according to the target temperature of the inlet of the catalyst so as to adjust the cooperative control temperature raising strategy. Further improves the temperature raising strategy by cooperative control, Controlling the electric supercharger to raise the intake pressure to a preset first intake pressure; An air inlet heating module is arranged at an air outlet of the electric supercharger, and the air inlet heating module is controlled to increase the air inlet temperature to a preset first air inlet temperature; Setting a first ignition advance angle retardation value, retarding a current ignition advance angle according to the first ignition advance angle retardation value, completely closing an EGR valve, setting a first air-fuel ratio and a second air-fuel ratio, injecting an inner cylinder core area according to the first air-fuel ratio, and injecting an inner cylinder edge area according to the second air-fuel ratio; and setting the opening of the exhaust throttle valve to a preset first opening. Further, the method for obtaining the target temperature of the inlet of the catalyst after executing the cooperative control temperature raising strategy comprises the following steps of, The method comprises the steps of obtaining the exhaust specific heat capacity, the pipeline length from a throttle valve outlet to a catalyst inlet, the pipeline heat dissipation coefficient, the environment temperature of an engine, the exhaust throttle valve outlet exhaust pressure and the turbine outlet exhaust pressure, calculating the exhaust throttle valve opening according to the exhaust throttle valve outlet exhaust pressure and the turbine outlet exhaust pressure, obtaining the natural gas combustion hea