Catalyst temperature rise protection method and device, vehicle and storage medium

Abstract

The embodiment of the invention provides a catalyst temperature rise protection method and device, a vehicle and a storage medium, and the method comprises the steps that when the opening degree of an accelerator pedal is 0% and the center temperature of a catalyst is larger than a first temperature threshold value, the ignition angle of an engine is controlled to be kept at a preset ignition angle; and when the center temperature of the catalytic converter is smaller than a second temperature threshold value, the engine is controlled to stop injecting fuel oil. When a driver loosens an accelerator and the center temperature of a catalytic converter is high, fuel cut-off of the engine is delayed, the ignition angle is properly increased, combustion occurs in the engine as much as possible, and the combustion tendency after combustion is reduced. Meanwhile, oxygen in exhausted gas is consumed, and oxidation heat release of hydrocarbon at high temperature is prevented. At the moment, the exhaust temperature is low, the center temperature of the catalytic converter can be reduced, and fuel injection is stopped after the center temperature of the catalytic converter is reduced. And the fuel economy is ensured while the high-temperature damage to the catalytic converter is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engine control, in particular to a catalyst temperature rise protection method and device, a vehicle and a storage medium. BACKGROUND

[0002] An engine is a machine that can convert chemical energy into mechanical energy. A controller can adjust the working state of the engine by controlling the ignition angle, throttle, fuel injection system, etc.

[0003] When a vehicle is running at high speed and high load, the engine has high combustion intensity, large fuel injection amount, and high exhaust gas temperature. The catalyst in the exhaust system continuously absorbs exhaust heat, causing the center temperature to rise. If the user releases the throttle at this time, the vehicle does not need to burn to maintain the speed due to inertia. Therefore, to optimize fuel economy, the engine control system usually controls the engine to be at minimum load, minimum ignition angle and stop fuel injection, only intake, invalid ignition and exhaust, that is, trigger fuel cut.

[0004] However, the above fuel cut control may cause the center temperature of the catalyst to rise instead of falling, and even exceed its tolerance limit, affecting the service life. Since the engine stops fuel injection but continues to intake, the oxygen content in the exhaust gas increases, causing unburned hydrocarbons (HC) in the exhaust system to have a violent oxidation reaction on the surface of the high-temperature catalyst, releasing a large amount of heat. Further, if a gasoline particulate filter (GPF) is integrated in the exhaust system, the carbon powder accumulated in the GPF will also be combusted again under high oxygen and high temperature, further increasing the temperature. This uncontrolled temperature rise will accelerate the aging and failure of the catalyst, causing its purification ability to decrease, not only shortening the service life, but also triggering a vehicle emission fault alarm, increasing maintenance or replacement costs.

[0005] It should be noted that the information disclosed in the background section of the present application is only intended to deepen the understanding of the general background of the present application, and should not be regarded as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art. SUMMARY

[0006] The embodiments of the present application provide a catalyst temperature rise protection method, device, vehicle and storage medium, which are beneficial to solve the problem that the center temperature of the catalyst abnormally rises and even exceeds its tolerance limit after the engine triggers fuel cut, affecting the service life.

[0007] In a first aspect, the embodiments of the present application provide a catalyst temperature rise protection method, which comprises: when the accelerator pedal opening is 0% and the center temperature of the catalyst is greater than a first temperature threshold value, the first temperature threshold value matching a tolerance temperature of the catalyst, and the preset ignition angle is greater than a minimum ignition angle, controlling an ignition angle of the engine to keep the preset ignition angle; when the center temperature of the catalyst is less than a second temperature threshold value, the second temperature threshold value being less than the first temperature threshold value, controlling the engine to stop injecting fuel.

[0008] In a possible implementation, after the control of the engine to stop injecting fuel, the method further includes: controlling a throttle opening to make the engine reach a preset load, the preset load being greater than a minimum load of the engine.

[0009] In a possible implementation, after the control of the throttle opening to make the engine reach the preset load, the method further includes: when the center temperature of the catalyst is less than a third temperature threshold value, the third temperature threshold value being less than the second temperature threshold value, controlling the throttle opening to make the engine reach the minimum load; controlling the ignition angle of the engine to keep a minimum ignition angle.

[0010] In a possible implementation, the control of the throttle opening to make the engine reach the minimum load when the center temperature of the catalyst is less than a third temperature threshold value includes: when the center temperature of the catalyst is less than the third temperature threshold value and the center temperature of the catalyst presents a downward trend, controlling the throttle opening to make the engine reach the minimum load.

[0011] In a possible implementation, the control of the ignition angle of the engine to keep the preset ignition angle when the accelerator pedal opening is 0% and the center temperature of the catalyst is greater than a first temperature threshold value includes: when the accelerator pedal opening is 0%, the center temperature of the catalyst is greater than the first temperature threshold value, and an exhaust temperature of the engine is greater than an exhaust temperature threshold value, controlling the ignition angle of the engine to keep the preset ignition angle.

[0012] In a possible implementation, the control of the engine to stop injecting fuel when the center temperature of the catalyst is less than a second temperature threshold value includes: when the center temperature of the catalyst is less than the second temperature threshold value and the center temperature of the catalyst presents a downward trend, controlling the engine to stop injecting fuel.

[0013] In a possible implementation, the preset ignition angle corresponds to a combustion torque of the engine that is less than a motoring torque of the engine.

[0014] In a second aspect, the embodiments of the present application provide a catalyst temperature rise protection device, the device comprising: an ignition angle control module configured to control the ignition angle of the engine to remain at a preset ignition angle when the accelerator pedal opening is 0% and the center temperature of the catalyst is greater than a first temperature threshold, the first temperature threshold matching a tolerance temperature of the catalyst, and the preset ignition angle being greater than a minimum ignition angle; a fuel control module configured to control the engine to stop injecting fuel when the center temperature of the catalyst is less than a second temperature threshold, the second temperature threshold being less than the first temperature threshold.

[0015] In a third aspect, the embodiments of the present application provide a vehicle, the vehicle comprising a controller configured to execute the method of any one of the first aspect.

[0016] In a fourth aspect, the embodiments of the present application provide a computer readable storage medium, the computer readable storage medium storing a computer program, the computer program being executed by a controller to implement the method of any one of the first aspect.

[0017] In the embodiments of the present application, when the driver releases the accelerator pedal and the center temperature of the catalyst is high, the engine delays fuel injection and appropriately increases the ignition angle, so that combustion occurs as much as possible in the engine, reducing the tendency of afterburning. At the same time, oxygen in the exhaust gas is consumed to prevent the oxidation and heat release of hydrocarbons at high temperatures. At this time, the exhaust gas temperature is low, which can reduce the center temperature of the catalyst, and fuel injection is stopped when the center temperature of the catalyst is reduced. This reduces the damage to the catalyst at high temperatures while ensuring fuel economy. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0019] Figure 1 A schematic diagram of an application scenario provided by the embodiments of the present application; Figure 2 A structural schematic diagram of an engine cylinder provided by the embodiments of the present application; Figure 3 A flowchart of a catalyst temperature rise protection method provided by the embodiments of the present application; Figure 4 A flowchart of another catalyst temperature rise protection method provided by the embodiments of the present application; Figure 5A flowchart of another catalytic converter temperature rise protection method provided in the embodiments of the present application is shown in FIG. 1. Figure 6 A structure diagram of a catalytic converter temperature rise protection device provided in the embodiments of the present application is shown in FIG. 2. Figure 7 A structure diagram of a vehicle provided in the embodiments of the present application is shown in FIG. 3. DETAILED DESCRIPTION

[0020] In order to better understand the technical solutions of the present application, the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0021] It should be clear that the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0022] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0023] It should be understood that the term "and / or" used herein is only to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are in an "or" relationship.

[0024] Referring to Figure 1 A schematic diagram of an application scenario provided in the embodiments of the present application is shown in FIG. 1. As Figure 1 shown, the application scenario shows a vehicle 100, which includes an engine 101 and a controller 102. Wherein, the engine 101 and the controller 102 are electrically connected.

[0025] Specifically, the engine 101 is the power source of the vehicle 100, which can convert the chemical energy of fuel into mechanical energy to drive the vehicle 100 through combustion. Taking a four-stroke engine as an example, the engine 101 realizes power output through four consecutive stroke cycles of intake, compression, work and exhaust. The intake stroke sucks in air and fuel mixture, which is compressed and ignited to release energy to drive the crankshaft to rotate, and finally the exhaust gas generated by combustion is discharged through the exhaust valve in the exhaust stroke. The controller 102 is a control unit in the vehicle 100, which can control the working state of the engine 101 by controlling the intake amount, fuel injection amount and ignition angle in the engine 101.

[0026] It should be pointed out that, such as Figure 1 The application scenarios shown are merely illustrative examples. Vehicles include, but are not limited to, sedans, MPVs, and SUVs; engines include, but are not limited to, gasoline engines, diesel engines, and gas engines; and controllers include, but are not limited to, MCUs and SOCs.

[0027] To better understand the technical solution of this application, the engine will be described in detail below with reference to the accompanying drawings.

[0028] See Figure 2 This is a schematic diagram of the structure of an engine cylinder provided in an embodiment of this application. Figure 2 As shown, it includes an intake valve 201, an exhaust valve 202, a spark plug 203, and a piston 204.

[0029] Specifically, taking a four-stroke engine as an example, the engine outputs power through a four-stroke cycle of intake, compression, power, and exhaust. During the intake stroke, the intake valve 201 opens and the exhaust valve 202 closes, the piston 204 moves downward, the cylinder volume increases to create negative pressure, and the air-fuel mixture is drawn into the cylinder; during the compression stroke, both the intake valve 201 and the exhaust valve 202 are closed, the piston 204 moves upward, compressing the mixture and increasing its temperature and pressure; during the power stroke, the spark plug 203 generates an electric spark to ignite the mixture, and the high-pressure gas produced by combustion pushes the piston 204 downward, driving the crankshaft to rotate and output power; during the exhaust stroke, the exhaust valve 202 opens and the intake valve 201 closes, the piston 204 moves upward, and the exhaust gas after combustion is discharged from the cylinder, and then discharged after being treated by the exhaust system.

[0030] Furthermore, such as Figure 2 As shown, during the compression stroke, both intake valve 201 and exhaust valve 202 are closed, and piston 204 moves upward to compress the air-fuel mixture. When the piston reaches the top of the cylinder, it reaches top dead center (TDC) of the compression stroke. The angle between the spark plug ignition timing and the piston reaching TDC is called the ignition angle. It can be understood that a proper ignition angle allows the peak combustion pressure to match the piston movement, and the controller can adjust the engine's operating state by controlling the ignition angle.

[0031] Furthermore, the engine also includes a throttle valve. Air flow is first regulated by the throttle valve and then delivered to the cylinders via the intake valve 201. The throttle valve controls the amount of air entering the cylinders, and its opening directly reflects the engine load. A larger throttle opening results in more air entering the cylinders, corresponding to an increase in fuel injection and greater engine power output; a smaller opening results in less air, less fuel injection, and reduced power output. It can be understood that the controller can regulate the engine's operating state by controlling the throttle valve.

[0032] In addition, the engine also includes an oil injection system, which is responsible for accurately injecting fuel into the cylinder or intake port in an atomized state, and mixing with air to form a combustible mixture. The amount of fuel injected in a single injection can be controlled according to signals such as throttle opening, speed, etc., to ensure that the air-fuel ratio of the mixture is in the ideal range; the timing of fuel injection can also be controlled to adapt to the air flow state in the cylinder, promote uniform mixing of the mixture, and reduce unburned fuel residues. It can be understood that the controller can adjust the working state of the engine by controlling the oil injection system.

[0033] It can be understood that when the vehicle is running at high speed and high load, the engine will increase the throttle opening to introduce more air during the intake stroke, and increase the amount of fuel injection, so that the combustion reaction is more intense and releases more heat to output more mechanical energy during the power stroke. Finally, the high-temperature exhaust gas generated by the intense combustion reaction is pushed out of the cylinder by the piston during the exhaust stroke and is discharged into the exhaust system. The catalyst in the exhaust system is in contact with the high-temperature exhaust gas continuously, and the catalyst absorbs a large amount of heat, resulting in a high center temperature of the catalyst.

[0034] Further, if the user releases the throttle in a high-speed and medium-high load state of the vehicle, the inertia of the vehicle can drive the engine to rotate through the transmission system without the need for combustion to maintain the speed. To optimize fuel economy, the engine control system will usually control the engine to be at minimum load, minimum ignition angle and stop fuel injection, only intake, invalid ignition and exhaust, i.e. trigger fuel cut. This control can reduce fuel consumption, and at the same time, use the engine drag resistance to achieve natural deceleration of the vehicle, which is a common fuel economy optimization strategy in related technologies.

[0035] Specifically, the minimum ignition angle and the minimum load match the critical combustion state of the engine when the fuel is not cut off. Among them, the minimum load is achieved by controlling the throttle opening, i.e. the throttle is kept at the minimum opening to limit the intake amount, so that the engine is in a critical combustion state; the minimum ignition angle is the ignition angle matched with the minimum load of the engine, which can reduce the combustion duration and heat release intensity, and maintain the critical combustion state of the engine.

[0036] However, the above fuel cut control can cause the center temperature of the catalyst to abnormally rise and even exceed its tolerance limit, affecting the service life. On the one hand, during high-speed high-load operation, the engine has high combustion intensity and high fuel injection amount, and the exhaust gas temperature is relatively high. The catalyst absorbs the heat of the exhaust gas continuously, resulting in a high center temperature. On the other hand, after the throttle is released and the fuel is cut, the engine stops injecting fuel but continues to intake air, and the oxygen content in the exhaust gas increases, causing the unburned hydrocarbons in the exhaust system to undergo a violent oxidation reaction on the surface of the high-temperature catalyst, releasing a large amount of heat. If the exhaust system integrates a particulate filter (GPF), the accumulated carbon powder will also undergo secondary combustion under rich oxygen and high temperature, further increasing the temperature. This uncontrolled temperature rise can accelerate the aging and failure of the catalyst, leading to a decrease in its purification capacity, not only shortening the service life, but also triggering a vehicle emission fault alarm and increasing maintenance or replacement costs.

[0037] To solve the above problems, the embodiments of the present application provide a catalyst temperature rise protection method. When the driver releases the throttle and the center temperature of the catalyst is high, the engine delays fuel cut and appropriately increases the ignition angle, so that combustion occurs as much as possible in the engine, reducing the tendency of post-combustion. At the same time, oxygen in the exhaust gas is consumed to prevent the oxidation and heat release of hydrocarbons at high temperatures. At this time, the exhaust gas temperature is relatively low, which can reduce the center temperature of the catalyst, and fuel injection is stopped when the center temperature of the catalyst is reduced. This reduces the damage to the catalyst caused by high temperature while ensuring fuel economy. In the following, specific embodiments will be described in detail in conjunction with the drawings.

[0038] Referring to Figure 3 , a flowchart of a catalyst temperature rise protection method provided by the embodiments of the present application is shown. The method can be used in Figure 1 the application scenario shown. As shown in Figure 3 , the method mainly includes the following steps: Step S301: When the throttle pedal opening degree is 0% and the center temperature of the catalyst is greater than a first temperature threshold, the ignition angle of the engine is controlled to remain at a preset ignition angle.

[0039] In the embodiments of the present application, fuel injection is not immediately stopped when the center temperature of the catalyst is higher than the first temperature threshold. By continuously injecting fuel to maintain combustion, oxygen in the exhaust gas is consumed to avoid subsequent heat release coupling reactions as much as possible.

[0040] Further, the center temperature of the catalyst can be obtained by a controller based on engine operating parameters (such as speed, fuel injection amount, and intake air amount) and a preset model. Of course, those skilled in the art can also select other ways to obtain the center temperature of the catalyst according to actual conditions, such as detection by a built-in temperature sensor or a non-contact temperature sensor in the catalyst, which is not limited herein.

[0041] The first temperature threshold matches the catalyst tolerance temperature and is used to determine whether the catalyst needs to be protected from temperature rise. The first temperature threshold can be set slightly lower than the catalyst tolerance temperature. Of course, those skilled in the art can also set other first temperature thresholds according to actual conditions, for example, setting the catalyst tolerance temperature as the first temperature threshold, which is not limited herein.

[0042] In practical applications, if the ignition angle is small, the late ignition time will cause the unburned mixture to enter the exhaust system, i.e. the afterburning phenomenon, which may cause the center temperature of the catalyst to rise.

[0043] To avoid the above problems as much as possible, the present scheme further introduces a preset ignition angle greater than the minimum ignition angle. On the one hand, by optimizing the ignition timing, the combustion is as much as possible to occur in the engine, reducing the afterburning phenomenon of unburned mixture entering the exhaust system; on the other hand, the preset ignition angle can produce exhaust gas with lower temperature to help the catalyst center dissipate heat; on the other hand, the preset ignition angle matches the reasonable combustion torque to prevent possible speed loss of control and achieve smooth transition from high load to reverse drag condition. In practical applications, there may be a situation where the center temperature of the catalyst is high but the exhaust temperature is low, at which time the exhaust can help the catalyst center dissipate heat, and the additional introduction of temperature rise protection control logic may increase energy consumption.

[0044] In one possible implementation, when the accelerator pedal opening is 0%, the center temperature of the catalyst is greater than the first temperature threshold, and the exhaust temperature of the engine is greater than the exhaust temperature threshold, the ignition angle of the engine is controlled to remain the preset ignition angle.

[0045] Similarly, the exhaust temperature can be estimated by combining engine operating parameters (such as speed, fuel injection amount, and intake amount) with an exhaust system thermal model, which can be used to determine the heat transfer direction between the exhaust and the catalyst.

[0046] Of course, those skilled in the art can also select other ways to obtain the exhaust temperature according to actual conditions, for example, directly collecting the exhaust temperature through a temperature sensing element in the exhaust system, which is not limited herein.

[0047] Further, the exhaust temperature threshold can be set based on whether the exhaust has heat dissipation capability. When the exhaust temperature is higher than the threshold, the exhaust may still transfer heat to the catalyst, and the catalyst still has the risk of temperature rise, and the catalyst temperature rise protection needs to be intervened. When the exhaust temperature is lower than the exhaust temperature threshold, the exhaust can absorb the heat of the catalyst through heat exchange and assist in heat dissipation, at which time no additional control logic is needed, which can reduce energy consumption.

[0048] In practical applications, if the combustion torque corresponding to the preset ignition angle is greater than the motoring torque, the engine still has power output, which does not conform to the control logic when the driver releases the accelerator (the accelerator pedal opening degree is 0%), and may increase the safety risk.

[0049] In a possible implementation, the combustion torque of the engine corresponding to the preset ignition angle is less than the motoring torque of the engine.

[0050] In practical applications, the combustion torque refers to the torque output when the high-pressure gas generated by the combustion of the mixture in the power stroke of the engine pushes the piston to move and then drives the crankshaft to rotate through the connecting rod. The size is jointly determined by the combustion energy and the conversion efficiency. It can be understood that the combustion torque is jointly affected by the throttle opening degree, fuel injection and ignition angle.

[0051] The combustion torque corresponding to the preset ignition angle is limited to be less than the motoring torque of the engine. On the one hand, it ensures that the engine is in the motoring state, and the vehicle can naturally slow down through the motoring resistance, which conforms to the control logic when the driver releases the accelerator; on the other hand, it is to control the combustion intensity, reduce the heat release, avoid the increase of the exhaust temperature, and create favorable conditions for the cooling of the catalyst; in addition, under the condition that the combustion torque corresponding to the preset ignition angle is less than the motoring torque, the engine can maintain necessary combustion to avoid the risk of oxygen enrichment caused by fuel cut, and does not output additional power, which takes into account the protection of the catalyst and the smoothness of the coasting.

[0052] Step S302: When the center temperature of the catalyst is less than the second temperature threshold, the engine is controlled to stop injecting fuel.

[0053] Specifically, the second temperature threshold is set, which is lower than the first temperature threshold, and further lower than the tolerance temperature of the catalyst. Further, when the center temperature of the catalyst decreases to the second temperature threshold, even if the subsequent fuel cut, because the intake air continuously enters the oxygen-rich environment, the oxidation heat intensity of the residual hydrocarbons is not enough to make the temperature rise to the risk level. Of course, those skilled in the art can also set the second temperature threshold in other ways according to the actual situation, for example, set a temperature value lower than the first temperature threshold by a fixed value as the second temperature threshold, which is not limited herein.

[0054] Further, when the center temperature of the catalyst is less than the second temperature threshold, the controller sends a stop injection instruction to the fuel injection system of the engine to terminate the fuel supply. Based on the combustion state under the control of the preset ignition angle, the fuel injection amount can be at a low level, so the fuel injection can be directly stopped without additional reduction process, which avoids fuel waste while ensuring smooth switching of the engine from the combustion state to the motoring state. It can be understood that the center temperature of the catalytic converter decreases at this time, and the exothermic oxidation of hydrocarbons and the secondary combustion are not triggered, the invalid fuel consumption after the fuel injection is stopped is avoided, and the fuel economy is increased; on the other hand, the fuel injection is stopped after the temperature is stable, and the risk of temperature rebound is further reduced.

[0055] In summary, when the driver releases the accelerator and the center temperature of the catalytic converter is high, the engine delays the fuel injection and appropriately increases the ignition angle, so that the combustion occurs as much as possible in the engine, and the afterburning tendency after the combustion is reduced. At the same time, the oxygen in the exhaust gas is consumed, and the exothermic oxidation of hydrocarbons at high temperature is prevented. At this time, the exhaust gas temperature is low, and the center temperature of the catalytic converter can be reduced, and the fuel injection is stopped when the center temperature of the catalytic converter is reduced. The fuel economy is ensured while reducing the damage of the catalytic converter at high temperature.

[0056] In actual application, the center temperature of the catalytic converter may not uniformly decrease to the second temperature threshold due to the afterburning tendency or the exothermic oxidation of hydrocarbons in the exhaust system, or even the center temperature of the catalytic converter rebounds. At this time, stopping the fuel injection may further cause the center temperature of the catalytic converter to rebound.

[0057] In one possible implementation, when the center temperature of the catalytic converter is less than the second temperature threshold, and the center temperature of the catalytic converter presents a decreasing trend, the engine is controlled to stop injecting fuel.

[0058] Specifically, whether the center temperature of the catalytic converter presents a decreasing trend can be determined by determining whether the temperature change amount of the center temperature of the catalytic converter in a unit time is greater than a preset value.

[0059] Of course, those skilled in the art can also select other ways to determine whether the center temperature of the catalytic converter presents a decreasing trend according to actual conditions, for example, by determining whether the center temperature of the catalytic converter rebounds in a unit time, so as to determine whether the center temperature of the catalytic converter presents a decreasing trend, which is not limited herein.

[0060] It can be understood that by increasing the decreasing trend determination, the fuel injection is stopped when the temperature temporarily decreases to the second threshold but rebounds subsequently, and the secondary temperature rise caused by the rich oxygen environment after the fuel injection is stopped is prevented. The application embodiment determines the triggering time of the fuel injection control under the premise of ensuring the safety of the catalytic converter, which not only ensures the fuel economy, but also effectively protects the temperature rise of the catalytic converter. In actual application, after the engine stops the fuel injection, if the intake amount decreases with the decrease of the load, the exhaust flow rate decreases, and the cooling speed of the catalytic converter decreases due to the weakening of heat exchange.

[0061] Referring to Figure 4 Another flowchart of a catalytic converter temperature rise protection method provided by the application embodiment is shown. As Figure 4 shown, the application embodiment determines whether the center temperature of the catalytic converter presents a decreasing trend, and controls the engine to stop injecting fuel when the center temperature of the catalytic converter presents a decreasing trend.Figure 3 On the basis of the embodiment shown, step S302 further specifically comprises the following steps: Step S401: Control the throttle opening degree to make the engine reach the preset load.

[0062] Specifically, as described above, the amount of air entering the cylinder is controlled by the throttle, and the opening degree thereof can directly reflect the engine load. The greater the throttle opening degree, the more air enters the cylinder.

[0063] It can be understood that the greater the throttle opening degree, the greater the subsequent exhaust flow. According to the current temperature state of the catalyst and the exhaust flow demand, the throttle can be adjusted to a specific opening degree, that is, the engine reaches the preset load. The intake air amount corresponding to the preset load is sufficient to maintain a high exhaust flow, which can perform sufficient heat exchange to remove the heat of the catalyst, thereby avoiding the slow-down of the catalyst cooling speed due to the reduction of the exhaust flow. On the other hand, the setting of the preset load can match the engine motoring condition characteristics, while ensuring the cooling effect, it avoids the increase of engine resistance due to the too large throttle opening degree, and ensures the smoothness of the vehicle during the sliding process, which realizes the catalyst temperature rise protection and does not affect the driving experience.

[0064] Of course, those skilled in the art can also select other ways to set the preset load according to the actual situation, for example, considering the fastest cooling, setting the maximum throttle opening degree as the engine preset load, which is not limited herein. In actual application, the engine continues to maintain a high throttle opening degree and ignition angle state after fuel cut. At this time, the intake air amount is large, which increases the engine motoring resistance and may also reduce the combustion stability when refueling.

[0065] Referring to Figure 5 Another flowchart of a catalyst temperature rise protection method provided by the embodiment of the present application is shown. As shown in Figure 5 The embodiment of the present application is based on Figure 4 On the basis of the embodiment shown, step S401 further specifically comprises the following steps: Step S501: When the center temperature of the catalyst is less than a third temperature threshold, control the throttle opening degree to make the engine reach the minimum load.

[0066] Specifically, the upper limit of the normal working temperature range of the catalyst can be taken as the third temperature threshold, which is lower than the second temperature threshold. At this time, the center temperature of the catalyst is far away from the high temperature risk, and even in the oxygen-rich environment, hydrocarbon oxidation exothermic or GPF carbon powder secondary combustion will not occur, and additional control of the throttle and ignition angle is not required. Therefore, when the center temperature of the catalyst is lower than the third temperature threshold, the throttle opening degree is controlled to make the engine reach the minimum load.

[0067] Of course, the third temperature threshold can also be set in other manners according to actual conditions, for example, a temperature value lower than the second temperature threshold by a fixed value is recorded as the third temperature threshold, which is not limited herein.

[0068] It can be understood that, as described above, the minimum load is achieved by controlling the throttle opening, that is, the throttle opening is kept small to limit the intake air amount, so that the engine is in a low air flow state, and the engine reaches the minimum load by controlling the throttle opening, which can reduce the engine drag resistance and improve the driving smoothness.

[0069] Step S502: control the ignition angle of the engine to keep the minimum ignition angle.

[0070] Specifically, as described above, the minimum ignition angle is the ignition angle corresponding to the minimum combustion torque and the minimum load of the engine, which can reduce the combustion duration and the heat release intensity. On the other hand, after the ignition angle of the engine is controlled to keep the minimum ignition angle, when the driver steps on the accelerator to restore power, the smooth transition from drag to work can be achieved by increasing the corresponding ignition angle, the power response delay is reduced, and the driving experience is improved.

[0071] In actual application, the center temperature of the catalyst may not uniformly decrease to the third temperature threshold due to the post-combustion tendency or oxidation of hydrocarbons in the exhaust system, and even the center temperature of the catalyst may rise. At this time, the engine may not reach the minimum load by controlling the throttle opening, which may cause the center temperature of the catalyst to be difficult to decrease stably.

[0072] In one possible implementation, when the center temperature of the catalyst is less than the third temperature threshold and the center temperature of the catalyst is in a decreasing trend, the engine is controlled to reach the minimum load by controlling the throttle opening.

[0073] Similarly, whether the center temperature of the catalyst is in a decreasing trend can be determined by determining whether the temperature change amount of the center temperature of the catalyst in a unit time is greater than a preset value.

[0074] Of course, whether the center temperature of the catalyst is in a decreasing trend can also be determined in other manners according to actual conditions, for example, by determining whether the center temperature of the catalyst exists a rising situation in a unit time, so as to determine whether the center temperature of the catalyst is in a decreasing trend, which is not limited herein.

[0075] Corresponding to the above-mentioned embodiments, the application also provides a catalyst temperature rise protection device.

[0076] Referring to Figure 6 A structural schematic diagram of a catalyst temperature rise protection device provided by the application is shown in FIG. 1. As shown in FIG. 1, the catalyst temperature rise protection device comprises a throttle opening control unit 1 and an ignition angle control unit 2. Figure 6As shown, the catalytic converter temperature rise protection device 600 includes an ignition angle control module 601 and a fuel control module 602.

[0077] The ignition angle control module 601 is configured to control the ignition angle of the engine to remain at a preset ignition angle when the accelerator pedal opening degree is 0% and the center temperature of the catalytic converter is greater than a first temperature threshold, the first temperature threshold matches the tolerance temperature of the catalytic converter, and the preset ignition angle is greater than a minimum ignition angle. The fuel control module 602 is configured to control the engine to stop injecting fuel when the center temperature of the catalytic converter is less than a second temperature threshold, and the second temperature threshold is less than the first temperature threshold.

[0078] For brevity of presentation, the detailed description of the embodiments of the present application can be referred to the description of the method embodiments.

[0079] Corresponding to the above embodiments, the embodiments of the present application also provide a vehicle.

[0080] Referring to Figure 7 , a structural schematic diagram of a vehicle provided by the embodiments of the present application is shown. As shown in Figure 7 , the vehicle 700 includes a controller 701. The controller 701 is configured to perform part or all of the steps in the method embodiments.

[0081] For brevity of presentation, the detailed description of the embodiments of the present application can be referred to the description of the method embodiments.

[0082] Corresponding to the above embodiments, the embodiments of the present application also provide a computer readable storage medium, wherein the computer readable storage medium can store a program, and when the program runs, the computer readable storage medium can control the device where the computer readable storage medium is located to perform part or all of the steps in the above method embodiments. In specific implementation, the computer readable storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0083] In the embodiments of the present application, "at least one" means one or more, and "multiple" means two or more. The "and / or" describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can represent the cases of A alone, A and B together, and B alone. Wherein A and B can be singular or plural. The character " / " generally represents an "or" relationship between the front and rear associated objects. "At least one of the following" and the like means any combination of these items, including any combination of single or multiple items. For example, at least one of a, b and c can represent: a, b, c, a-b, a-c, b-c, or a-b-c, where a, b, c can be single or multiple.

[0084] Those skilled in the art can appreciate that the units and algorithm steps described in the embodiments disclosed herein can be realized by electronic hardware, computer software and combination of electronic hardware and computer software. Whether the functions are realized in hardware or software mode depends on the specific application and design constraints of the technical solution. The skilled person can use different methods to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0085] Those skilled in the art can clearly understand that, for the convenience and brevity of the description, the specific working processes of the above-described devices, controllers and computer storage media can refer to the corresponding processes in the foregoing method embodiments, which will not be described here.

[0086] In several embodiments provided in the present application, any function realized in the form of a software function unit and sold or used as an independent product can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the parts that make contributions to the prior art or parts of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the embodiments of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various media that can store program codes.

[0087] The above is only a specific implementation of the present application. Any skilled person in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application. The protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for protecting a catalyst from temperature rise, characterized in that, include: When the accelerator pedal opening is 0% and the center temperature of the catalyst is greater than the first temperature threshold, the engine ignition angle is controlled to maintain a preset ignition angle. The first temperature threshold matches the tolerance temperature of the catalyst, and the preset ignition angle is greater than the minimum ignition angle. When the center temperature of the catalyst is lower than a second temperature threshold, the engine is controlled to stop injecting fuel, where the second temperature threshold is lower than the first temperature threshold.

2. The method according to claim 1, characterized in that, After controlling the engine to stop injecting fuel, the method further includes: The throttle opening is controlled to bring the engine to a preset load, which is greater than the engine's minimum load.

3. The method according to claim 2, characterized in that, After controlling the throttle opening to bring the engine to a preset load, the method further includes: When the center temperature of the catalyst is less than the third temperature threshold, the throttle opening is controlled to make the engine reach the minimum load, where the third temperature threshold is less than the second temperature threshold. The engine's ignition angle is controlled to maintain a minimum ignition angle.

4. The method according to claim 3, characterized in that, When the center temperature of the catalyst is less than a third temperature threshold, controlling the throttle opening to bring the engine to minimum load includes: When the center temperature of the catalyst is less than the third temperature threshold and the center temperature of the catalyst shows a downward trend, the throttle opening is controlled to make the engine reach the minimum load.

5. The method according to claim 1, characterized in that, When the accelerator pedal opening is 0% and the center temperature of the catalyst is greater than a first temperature threshold, controlling the engine's ignition angle to maintain a preset ignition angle includes: When the accelerator pedal opening is 0%, the center temperature of the catalyst is greater than the first temperature threshold, and the exhaust temperature of the engine is greater than the exhaust temperature threshold, the engine's ignition angle is controlled to maintain a preset ignition angle.

6. The method according to claim 1, characterized in that, The step of controlling the engine to stop injecting fuel when the center temperature of the catalyst is lower than the second temperature threshold includes: When the center temperature of the catalyst is lower than the second temperature threshold and the center temperature of the catalyst shows a downward trend, the engine is controlled to stop injecting fuel.

7. The method according to claim 1, characterized in that, The combustion torque of the engine corresponding to the preset ignition angle is less than the engine's drag torque.

8. A catalyst temperature rise protection device, characterized in that, include: The ignition angle control module is used to control the engine ignition angle to maintain a preset ignition angle when the accelerator pedal opening is 0% and the center temperature of the catalyst is greater than a first temperature threshold. The first temperature threshold is matched with the tolerance temperature of the catalyst, and the preset ignition angle is greater than the minimum ignition angle. A fuel control module is used to control the engine to stop injecting fuel when the center temperature of the catalyst is lower than a second temperature threshold, wherein the second temperature threshold is lower than the first temperature threshold.

9. A vehicle, characterized in that, include: A controller configured to perform the method according to any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which, when executed by the controller, implements the method described in any one of claims 1-7.

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