Method and system for improving small load combustion stability of motorcycle engine and motorcycle

Abstract

The application discloses a motorcycle engine small-load combustion stability improvement method and system and a motorcycle, and relates to the field of motorcycle engines.The method comprises the following steps: S1, judging whether the engine meets the condition of deceleration oil return to idle speed, if yes, entering step S2, if not, repeating step S1; S2, compensating for a set amount of fuel to perform open-loop control of air-fuel ratio; if the duration of the open-loop control meets a set time T, entering step S3; if the throttle opening is greater than or equal to a set opening K, exiting the open-loop control and entering closed-loop control; S3, judging again whether the engine meets the condition of deceleration oil return to idle speed, if yes, returning to step S2, if not, exiting the open-loop control and entering closed-loop control.The application can effectively accelerate the engine combustion rate, reduce the engine combustion cycle misfire frequency, and improve the engine combustion stability.

Description

Technical Field

[0001] This invention relates to the field of engine management, specifically to a method, system, and motorcycle for improving the combustion stability of a motorcycle engine under low load. Background Technology

[0002] Gasoline engines experience low intake air volume under low load, resulting in a high exhaust gas residue ratio and insufficient in-cylinder flow. These characteristics of gasoline engines lead to poor combustion stability under low load. This is especially true for motorcycle engines during deceleration and throttle return, when the throttle opening is at its minimum and the engine speed is higher than idle speed, resulting in a stronger throttling effect and making it one of the worst combustion conditions for motorcycle engines.

[0003] Conventional motorcycle engine control strategies, considering emissions factors, typically set the air-fuel ratio closed-loop control during deceleration and throttle return, with a target air-fuel ratio of 14.6 (theoretical air-fuel ratio). However, during deceleration and throttle return, the engine intake volume is smaller, and the result of the air-fuel ratio closed-loop control is a slower combustion rate, which can easily lead to engine stalling during the deceleration and throttle return to idle speed.

[0004] Therefore, in order to solve the problem of poor combustion or even stalling during the deceleration and oil return process of an engine to idle speed, a method, system and motorcycle for improving the combustion stability of a motorcycle engine under low load are needed, which can effectively accelerate the engine combustion rate, reduce the frequency of engine stalling during combustion cycles and improve engine combustion stability. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to overcome the defects in the prior art and provide a method, system and motorcycle for improving the combustion stability of a motorcycle engine under low load, which can effectively accelerate the engine combustion rate, reduce the engine combustion cycle shutdown frequency and improve the engine combustion stability.

[0006] The method for improving the low-load combustion stability of a motorcycle engine according to the present invention includes the following steps:

[0007] S1. Determine if the engine meets the conditions for deceleration and return to idle speed. If yes, proceed to step S2; otherwise, repeat step S1.

[0008] S2. Perform open-loop control of air-fuel ratio by compensating for a set amount of fuel; if the duration of the open-loop control meets the set time T, proceed to step S3; if the throttle opening is greater than or equal to the set opening K, exit the open-loop control and enter closed-loop control.

[0009] S3. Determine again whether the engine meets the conditions for deceleration and oil return to idle speed. If yes, return to step S2; otherwise, exit the open-loop control and enter closed-loop control.

[0010] Furthermore, the conditions for the engine to decelerate and return to idle speed include throttle opening conditions, engine speed conditions, and engine non-starting conditions.

[0011] The throttle opening condition includes that the throttle opening is not greater than the set opening K1 under idle conditions;

[0012] The engine speed conditions include the speed conditions under deceleration fuel cut-off conditions and the speed conditions under deceleration non-fuel cut-off conditions; wherein, under deceleration fuel cut-off conditions, the engine speed after fuel supply is restored after deceleration reaches a predetermined speed; under deceleration non-fuel cut-off conditions, the engine speed is between the idle speed plus a lower threshold and the idle speed plus a higher threshold.

[0013] Furthermore, the deceleration non-fuel cut-off condition is defined as throttle opening <1% and engine speed below 3000 rpm.

[0014] Furthermore, the air-fuel ratio is controlled in an open-loop manner by compensating for a set amount of fuel, specifically including:

[0015] According to engine combustion theory, the enrichment compensation setting of the fuel quantity ensures that the real air-fuel ratio under open-loop control is controlled between 12.2 and 13.3.

[0016] Furthermore, the set fuel quantity is obtained using the following method:

[0017] Divide the amount of air taken by the engine by the target air-fuel ratio to obtain the base fuel quantity;

[0018] Multiply the base fuel quantity by the set fuel compensation coefficient to obtain the set fuel quantity.

[0019] Furthermore, during the enrichment and compensation process, fuel compensation attenuation occurs once per engine working cycle, causing the fuel compensation coefficient to gradually decrease.

[0020] Furthermore, after the engine starts, if the fuel compensation degradation has not ended when the conditions for deceleration and return to idle speed are met, the fuel enrichment compensation for engine deceleration and return to idle speed will not be performed.

[0021] A system for improving combustion stability of a motorcycle engine under low load includes a working condition identification unit, an enrichment open-loop control unit, and a closed-loop control unit.

[0022] The operating condition identification unit is used to determine whether the engine meets the conditions for deceleration and oil return to idle speed.

[0023] The enrichment open-loop control unit is used to compensate a set amount of fuel for open-loop control of the air-fuel ratio when the engine meets the conditions of deceleration and oil return to idle speed.

[0024] The closed-loop control unit is used to perform closed-loop control when the engine meets the conditions for exiting the open-loop control.

[0025] A motorcycle, wherein the motorcycle employs the motorcycle engine low-load combustion stability improvement method and / or the motorcycle engine low-load combustion stability improvement system.

[0026] The beneficial effects of this invention are as follows: The method, system, and motorcycle disclosed herein for improving the combustion stability of a motorcycle engine under low load effectively identify the specific operating condition of the engine decelerating back to idle speed by using conditions such as engine speed and throttle opening. Within this specific operating condition, open-loop control of the air-fuel ratio is set and a certain proportion of fuel is compensated. When the engine speed drops back to idle speed, closed-loop fuel control is then implemented. This effectively solves the problem of poor combustion or even stalling during the engine deceleration back to idle speed. Moreover, because the enrichment compensation time is short and the load of the operating condition is extremely low, it has virtually no impact on emissions. Attached Figure Description

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0028] Figure 1 This is a schematic diagram of the combustion stability improvement control of the present invention;

[0029] Figure 2 This is a schematic diagram illustrating the fuel compensation coefficient setting based on engine coolant temperature according to the present invention. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings, as shown in the figures:

[0031] The method for improving the low-load combustion stability of a motorcycle engine according to the present invention, such as... Figure 1 As shown, it includes the following steps:

[0032] S1. Determine if the engine meets the conditions for deceleration and return to idle speed. If yes, proceed to step S2; otherwise, repeat step S1.

[0033] S2. Perform open-loop control of air-fuel ratio by compensating for a set amount of fuel; if the duration of the open-loop control meets the set time T, proceed to step S3; if the throttle opening is greater than or equal to the set opening K, exit the open-loop control and enter closed-loop control; wherein, the time T can be calibrated according to the time it takes for the engine speed to drop to idle speed, and the time T determines the duration of the open-loop control, and the value can be 5 to 8 seconds; the opening K can be set to 1%;

[0034] S3. Determine again whether the engine meets the conditions for deceleration and oil return to idle speed. If yes, return to step S2; otherwise, exit the open-loop control and enter closed-loop control. The closed-loop control uses existing closed-loop control technology, which will not be elaborated further here.

[0035] This invention can effectively accelerate the engine combustion rate, reduce the frequency of engine combustion cycle shutdown or even misfire, improve engine combustion stability, and reduce the generation of THC emissions by controlling the fuel to idle speed under deceleration and oil return conditions.

[0036] In this embodiment, the conditions for the engine to decelerate and return to idle speed include throttle opening conditions, engine speed conditions, and engine non-starting conditions; wherein, the engine non-starting condition means that the engine is in a non-starting operating condition.

[0037] The throttle opening condition includes that the throttle opening under idling conditions is not greater than the set opening K1; wherein, the opening K1 can be calibrated according to the actual operating conditions, for example, it can be taken as 1%; that is, the throttle opening condition must meet the small throttle opening under idling conditions.

[0038] The engine speed conditions include the speed conditions under deceleration fuel cut-off conditions and the speed conditions under deceleration non-fuel cut-off conditions; wherein, under deceleration fuel cut-off conditions, the engine speed at which fuel supply is restored after deceleration fuel cut-off reaches a predetermined speed; that is, if it is under deceleration fuel cut-off conditions, fuel compensation enrichment is performed starting from the engine speed at which fuel supply is restored after deceleration fuel cut-off (generally, the engine speed at which fuel supply is restored after deceleration fuel cut-off on motorcycles is around 2500 rpm).

[0039] Under deceleration without fuel cut-off conditions, the engine speed should be between idle speed plus a low threshold and idle speed plus a high threshold. That is, under deceleration without fuel cut-off conditions (throttle opening <1%, and engine speed below 3000 rpm), the engine speed needs to be between idle speed plus a low threshold X and idle speed plus a high threshold Y (i.e., idle speed + X ≤ engine speed ≤ idle speed + Y). The low threshold X and high threshold Y can be calibrated according to actual conditions; the low threshold X can be set to 200, and the high threshold Y can be set to 1000, and the thresholds can be fine-tuned based on the actual performance of the vehicle.

[0040] By setting multiple conditions to trigger open-loop air-fuel ratio control, the engine control is adjusted more precisely while taking into account safety, stability, and environmental protection, which helps the engine achieve better performance.

[0041] In this embodiment, the air-fuel ratio is controlled in an open-loop manner by compensating for a set amount of fuel, specifically including:

[0042] According to engine combustion theory, the enrichment compensation setting ensures that the true air-fuel ratio under open-loop control is maintained between 12.2 and 13.3. In open-loop control, air-fuel enrichment is achieved by additionally compensating with a certain proportion of fuel. According to relevant engine combustion theories, the compensating fuel proportion is generally controlled between 10% and 20%, thus ensuring that the true air-fuel ratio under open-loop control is maintained between 12.2 and 13.3.

[0043] Through the above control, within a certain range, a slightly richer combustion (12.2-13.3) is beneficial to improve combustion efficiency, reduce emissions of harmful pollutants such as carbon monoxide and nitrogen oxides, ensure higher engine power output, and improve vehicle performance.

[0044] In this embodiment, the set fuel quantity is obtained according to the following method:

[0045] Divide the amount of air obtained by the engine by the target air-fuel ratio to obtain the base fuel quantity; where the target air-fuel ratio is 14.6; multiply the base fuel quantity by the set fuel compensation coefficient to obtain the set fuel quantity.

[0046] Design a two-dimensional MAP for the fuel compensation coefficient F. This fuel compensation coefficient F is the initial fuel compensation coefficient triggered after the fuel enrichment compensation control logic is activated when the deceleration return to idle speed condition is met. F increases with engine temperature; the lower the engine temperature, the larger F becomes. The fuel compensation coefficient is based on a base fuel with a target air-fuel ratio of 14.6. Increasing fuel compensation is equivalent to enriching the target air-fuel ratio. For example, ... Figure 2 As shown, when the engine coolant temperature is 0 degrees, the fuel compensation coefficient is 1.18. Multiplying the base fuel quantity by 1.18 gives the required fuel quantity, which is more than the base fuel quantity, thus increasing the fuel compensation.

[0047] When the engine temperature is low, more fuel enrichment can be added. Fuel enrichment adjusts the engine's power output to a certain extent, achieves a good air-fuel ratio, and helps optimize combustion efficiency.

[0048] In this embodiment, during the enrichment and compensation of the set fuel quantity, fuel compensation attenuation is performed once in each working cycle of the engine, causing the fuel compensation coefficient to gradually decrease. For a four-stroke engine, one working cycle at 1500 rpm takes 80 milliseconds; the working cycle time varies for different stroke engines and will not be elaborated here. The fuel enrichment and compensation attenuation coefficient S can be set to determine the rate of decrease of the fuel compensation coefficient F during open-loop control. The attenuation coefficient S is set to 2% to 3%. For example, when the fuel compensation coefficient F is 1.18, each fuel compensation attenuation reduces the fuel compensation coefficient F by 2% to 3%, achieving a gradual decrease in the fuel compensation coefficient. When the fuel compensation coefficient F decreases to 1 or the duration of open-loop control reaches the set time T, it stops decreasing.

[0049] Because the initial fuel enrichment during fuel enrichment is richer, a smooth transition in fuel adjustment can be achieved by gradually reducing the enrichment rate. This avoids the impact of sudden changes on the engine, reduces the shock to the mechanical and power systems, and improves engine stability.

[0050] Furthermore, the exit conditions for fuel enrichment compensation control are explained as follows:

[0051] When the engine speed drops back to idle, and the duration of open-loop control meets the set time T, the fuel enrichment compensation control exits, and the fuel control returns to closed-loop control.

[0052] When the engine is in deceleration and oil return mode and is performing fuel enrichment compensation control, if the throttle opening suddenly increases, for example, to a value greater than or equal to K, the fuel enrichment compensation control strategy will be immediately exited and the fuel closed-loop control will be entered.

[0053] In this embodiment, after the engine starts and the conditions for deceleration and oil return to idle speed are met, if the fuel compensation decay has not ended, the fuel enrichment compensation for engine deceleration and oil return will not be performed.

[0054] Specifically, when the engine starts successfully and the speed rises and then falls, the specific operating condition of the engine decelerating back to idle speed may be met. However, at this time, the fuel compensation coefficient used solely for starting has not yet finished decaying, and the air-fuel ratio of the mixture is already relatively rich, making it unsuitable to perform fuel enrichment compensation again. Therefore, if the starting compensation fuel coefficient has not finished decaying when the specific operating condition of the engine decelerating back to idle speed is met after starting, the fuel enrichment compensation control for engine deceleration back to idle speed will not be executed.

[0055] The present invention also discloses a system for improving the low-load combustion stability of a motorcycle engine, which corresponds to the above-mentioned method for improving the low-load combustion stability of a motorcycle engine and can be understood as a system for implementing the above-mentioned improvement method. The improvement system includes a working condition identification unit, an enrichment open-loop control unit, and a closed-loop control unit.

[0056] The operating condition identification unit is used to determine whether the engine meets the conditions for deceleration and oil return to idle speed.

[0057] The enrichment open-loop control unit is used to compensate a set amount of fuel for open-loop control of the air-fuel ratio when the engine meets the conditions of deceleration and oil return to idle speed.

[0058] The closed-loop control unit is used to perform closed-loop control when the engine meets the conditions for exiting the open-loop control.

[0059] The present invention also discloses a motorcycle, wherein the motorcycle employs the motorcycle engine low-load combustion stability improvement method and / or the motorcycle engine low-load combustion stability improvement system described in the above embodiments.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for improving the combustion stability of a motorcycle engine under low load, characterized in that: Includes the following steps: S1. Determine if the engine meets the conditions for deceleration and return to idle speed. If yes, proceed to step S2; otherwise, repeat step S1. The conditions for the engine to decelerate and return to idle speed include engine non-starting conditions, engine speed conditions, and throttle opening conditions. The engine speed conditions include the speed conditions under deceleration fuel cut-off conditions and the speed conditions under deceleration non-fuel cut-off conditions; wherein, under deceleration fuel cut-off conditions, the engine speed after fuel supply is restored after deceleration reaches a predetermined speed; under deceleration non-fuel cut-off conditions, the engine speed is between idle speed plus a low threshold and idle speed plus a high threshold. The throttle opening condition includes that the throttle opening is not greater than the set opening K1 under idle conditions; S2. The air-fuel ratio is controlled in an open-loop manner by compensating for a set amount of fuel. According to engine combustion theory, the set amount of fuel is enriched to compensate for the fuel quantity. During the enrichment and compensation of the set amount of fuel, fuel compensation attenuation is performed once in each working cycle of the engine, so that the fuel compensation coefficient gradually decreases. If the duration of the open-loop control meets the set time T, then proceed to step S3. If the throttle opening is greater than or equal to the set opening K, then exit the open-loop control and enter closed-loop control. S3. Determine again whether the engine meets the conditions for deceleration and oil return to idle speed. If yes, return to step S2; otherwise, exit the open-loop control and enter closed-loop control.

2. The method for improving the low-load combustion stability of a motorcycle engine according to claim 1, characterized in that: The deceleration non-fuel cut-off condition is defined as throttle opening <1% and engine speed below 3000 rpm.

3. The method for improving the low-load combustion stability of a motorcycle engine according to claim 1, characterized in that: The air-fuel ratio is controlled in an open-loop manner by compensating for a set amount of fuel, specifically by controlling the actual air-fuel ratio under open-loop control to be between 12.2 and 13.

3.

4. The method for improving the low-load combustion stability of a motorcycle engine according to claim 3, characterized in that: The set fuel quantity can be obtained using the following method: Divide the amount of air taken by the engine by the target air-fuel ratio to obtain the base fuel quantity; Multiply the base fuel quantity by the set fuel compensation coefficient to obtain the set fuel quantity.

5. The method for improving the low-load combustion stability of a motorcycle engine according to claim 4, characterized in that: After the engine starts, if the fuel compensation degradation has not ended when the conditions for deceleration and return to idle speed are met, the fuel enrichment compensation for engine deceleration and return to idle speed will not be performed.

6. A system for improving the low-load combustion stability of a motorcycle engine, implementing the method for improving the low-load combustion stability of a motorcycle engine according to any one of claims 1-5, characterized in that: It includes a working condition identification unit, an open-loop concentration control unit, and a closed-loop control unit; The operating condition identification unit is used to determine whether the engine meets the conditions for deceleration and oil return to idle speed. The enrichment open-loop control unit is used to compensate a set amount of fuel for open-loop control of the air-fuel ratio when the engine meets the conditions of deceleration and oil return to idle speed. The closed-loop control unit is used to perform closed-loop control when the engine meets the conditions for exiting the open-loop control.

7. A motorcycle, characterized in that: The motorcycle employs the motorcycle engine low-load combustion stability improvement method according to any one of claims 1-5 and / or the motorcycle engine low-load combustion stability improvement system according to claim 6.

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