阅读说明：本技术 发动机进气门包角及气门重叠角的控制方法 (Control method for wrap angle and valve overlap angle of engine intake valve ) 是由 张德胜 彭飞 李亮 刘亚奇 晏双鹤 黄松 董鑫 于 2019-10-17 设计创作，主要内容包括：本发明提供了一种发动机进气门包角及气门重叠角的控制方法,本确定方法包括：检测发动机转速；当发动机转速处于预设转速阈值区间时,以预设间隔逐次调整所述发动机的进气门包角和气门重叠角；根据调整后的所述进气门包角和所述气门重叠角,控制发动机的进气门和排气门动作。本发明所述的确定方法,能够合理确定发动机进气门包角以及气门重叠角,从而降低催化器的进气温度,降低发动机排气污染物含量,并可降低发动机的油耗。(The invention provides a control method of an engine intake valve wrap angle and a valve overlap angle, and the determination method comprises the following steps: detecting the rotating speed of the engine; when the rotating speed of the engine is in a preset rotating speed threshold interval, adjusting an inlet valve wrap angle and an valve overlap angle of the engine at preset intervals; and controlling the actions of an intake valve and an exhaust valve of the engine according to the adjusted wrap angle of the intake valve and the adjusted overlap angle of the valve. The determining method can reasonably determine the wrap angle and the valve overlap angle of the intake valve of the engine, thereby reducing the intake temperature of the catalyst, reducing the content of exhaust pollutants of the engine and reducing the oil consumption of the engine.)

1. A method for controlling an engine intake valve wrap angle and valve overlap angle, comprising:

detecting the rotating speed of the engine;

when the rotating speed of the engine is in a preset rotating speed threshold interval, adjusting an inlet valve wrap angle and an valve overlap angle of the engine at preset intervals;

and controlling the actions of an intake valve and an exhaust valve of the engine according to the adjusted wrap angle of the intake valve and the adjusted overlap angle of the valve.

2. The engine intake valve wrap angle and valve overlap angle control method of claim 1, wherein said controlling intake and exhaust valve events of the engine based on the adjusted intake valve wrap angle and valve overlap angle comprises:

acquiring the exhaust pollutant content and/or the exhaust catalyst inlet temperature corresponding to the inlet valve wrap angle and the valve overlap angle of the engine which are adjusted at preset intervals each time;

and comparing the exhaust pollutant content and/or the exhaust catalyst inlet temperature corresponding to the inlet valve wrap angle and the valve overlap angle of the engine which are adjusted at preset intervals each time, determining the inlet valve wrap angle and the valve overlap angle corresponding to the lowest exhaust pollutant content or the lowest exhaust catalyst inlet temperature as the inlet valve wrap angle and the valve overlap angle of the engine, and controlling the actions of an inlet valve and an exhaust valve of the engine.

3. The engine intake valve wrap angle and valve overlap angle control method of claim 1, wherein said controlling intake and exhaust valve events of the engine based on the adjusted intake valve wrap angle and valve overlap angle comprises:

acquiring the exhaust pollutant content and/or the exhaust catalyst inlet temperature corresponding to the inlet valve wrap angle and the valve overlap angle of the engine which are adjusted at preset intervals each time; and when the exhaust pollutant content or the intake temperature of the exhaust catalyst meets a preset condition, controlling the actions of an intake valve and an exhaust valve of the engine according to the adjusted intake valve wrap angle and valve overlap angle of the engine.

4. The engine intake valve wrap angle and valve overlap angle control method of claim 1, characterized in that: the preset rotating speed threshold interval is below 1500 rpm.

5. The engine intake valve wrap angle and valve overlap angle control method of claim 4, characterized in that: and the inlet valve wrap angle is decreased progressively according to the preset interval from the maximum inlet valve wrap angle of the engine.

6. The engine intake valve wrap angle and valve overlap angle control method of claim 5, characterized in that: the preset interval is 5 degrees CA, and the maximum reduction of the wrap angle of the inlet valve is 15-20 degrees CA.

7. The engine intake valve wrap angle and valve overlap angle control method of claim 4, characterized in that: the advance angle of the intake valve in the valve overlap angle is started from 30 degrees CA and is decreased at intervals of 5 degrees CA; the maximum reduction amount of the advance angle of the intake valve is less than 10-15 degrees CA.

8. The engine intake valve wrap angle and valve overlap angle control method of claim 4, characterized in that: the exhaust valve retard angle in the valve overlap angle is started from 30 ° CA and decreases at intervals of 5 ° CA.

9. The engine intake valve wrap angle and valve overlap angle control method of claim 8, characterized in that: the maximum reduction amount of the exhaust valve closing delay angle is between 5 and 10 degrees CA.

10. The engine intake valve wrap angle and valve overlap angle control method according to any one of claims 1 to 9, characterized in that: before the control of the actions of the intake valve and the exhaust valve of the engine according to the adjusted intake valve wrap angle and the adjusted valve overlap angle, the method further comprises the following steps:

detecting a vibration frequency of a supercharger of the engine;

and when the vibration frequency of the supercharger is lower than the surging judgment frequency of the supercharger, controlling the actions of an intake valve and an exhaust valve of the engine according to the adjusted wrap angle of the intake valve and the valve overlap angle.

Technical Field

The invention relates to the technical field of engine control, in particular to a control method for an inlet valve wrap angle and a valve overlap angle of an engine.

Background

The automobile industry is the most main consumer of petrochemical energy, and meanwhile, automobile exhaust is also an important source of atmospheric pollutants, so the automobile industry still faces greater pressure of energy conservation and emission reduction. CVVL (continuous valve lift adjustment) is one of the more advanced technologies used in engines, which has certain benefits on engine oil consumption and emission, but how to use CVVL in different working conditions is still a more prominent technical problem. The existing CVVL system usually uses the maximum lift and the maximum wrap angle in order to improve the air inflow and the air charging efficiency near the low-speed external characteristic working condition, and the corresponding VVT control also tends to use a larger valve overlap angle.

Disclosure of Invention

In view of the above, the present invention is directed to a method for controlling an intake valve wrap angle and a valve overlap angle of an engine, so as to improve the thermal efficiency of the engine and reduce the emissions of the engine.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

a method for controlling an engine intake valve wrap angle and valve overlap angle, comprising:

detecting the rotating speed of the engine;

when the rotating speed of the engine is in a preset rotating speed threshold interval, adjusting an inlet valve wrap angle and an valve overlap angle of the engine at preset intervals;

and controlling the actions of an intake valve and an exhaust valve of the engine according to the adjusted wrap angle of the intake valve and the adjusted overlap angle of the valve.

Further, the controlling the actions of the intake valve and the exhaust valve of the engine according to the adjusted intake valve wrap angle and the adjusted valve overlap angle comprises the following steps:

acquiring the exhaust pollutant content and/or the exhaust catalyst inlet temperature corresponding to the inlet valve wrap angle and the valve overlap angle of the engine which are adjusted at preset intervals each time;

and comparing the exhaust pollutant content and/or the exhaust catalyst inlet temperature corresponding to the inlet valve wrap angle and the valve overlap angle of the engine which are adjusted at preset intervals each time, determining the inlet valve wrap angle and the valve overlap angle corresponding to the lowest exhaust pollutant content or the lowest exhaust catalyst inlet temperature as the inlet valve wrap angle and the valve overlap angle of the engine, and controlling the actions of an inlet valve and an exhaust valve of the engine.

Further, the controlling the actions of the intake valve and the exhaust valve of the engine according to the adjusted intake valve wrap angle and the adjusted valve overlap angle comprises the following steps:

acquiring the exhaust pollutant content and/or the exhaust catalyst inlet temperature corresponding to the inlet valve wrap angle and the valve overlap angle of the engine which are adjusted at preset intervals each time; and when the exhaust pollutant content or the intake temperature of the exhaust catalyst meets a preset condition, controlling the actions of an intake valve and an exhaust valve of the engine according to the adjusted intake valve wrap angle and valve overlap angle of the engine.

Further, the preset rotation speed threshold interval is below 1500 rpm.

Further, the inlet valve wrap angle is decreased progressively according to the preset interval from the maximum inlet valve wrap angle of the engine.

Further, the preset interval is 5 degrees CA, and the maximum reduction amount of the wrap angle of the inlet valve is 15-20 degrees CA.

Further, the advance angle of the intake valve in the valve overlap angle is started from 30 DEG CA and is decreased at intervals of 5 DEG CA; the maximum reduction amount of the advance angle of the intake valve is less than 10-15 degrees CA.

Further, the exhaust valve retard angle in the valve overlap angle is started from 30 ° CA and decreases at intervals of 5 ° CA.

Further, the maximum reduction amount of the exhaust valve closing delay angle is between 5 and 10 degrees CA.

Further, before controlling the actions of the intake valve and the exhaust valve of the engine according to the adjusted intake valve wrap angle and the adjusted valve overlap angle, the method further comprises the following steps:

detecting a vibration frequency of a supercharger of the engine;

and when the vibration frequency of the supercharger is lower than the surging judgment frequency of the supercharger, controlling the actions of an intake valve and an exhaust valve of the engine according to the adjusted wrap angle of the intake valve and the valve overlap angle.

Compared with the prior art, the invention has the following advantages:

the invention provides a control method of an engine intake valve wrap angle and a valve overlap angle, which comprises the steps of adjusting the intake valve wrap angle and the valve overlap angle of an engine at preset intervals in a preset rotating speed threshold interval, and controlling the actions of an intake valve and an exhaust valve of the engine according to the adjusted intake valve wrap angle and the adjusted valve overlap angle. The exhaust catalytic converter can reduce the pollutant content discharged by the engine, reduce the air inlet temperature of the exhaust catalytic converter and improve the heat efficiency of the engine, thereby being beneficial to the energy conservation and emission reduction of vehicles.

Detailed Description

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

Example one

The embodiment relates to a control method of an engine intake valve wrap angle and a valve overlap angle, and the determination method comprises the following steps: detecting the rotating speed of the engine; when the rotating speed of the engine is in a preset rotating speed threshold interval, reducing an intake valve wrap angle and a valve overlap angle of the engine at preset intervals; and controlling the actions of an intake valve and an exhaust valve of the engine according to the adjusted wrap angle of the intake valve and the adjusted overlap angle of the valve.

Controlling intake and exhaust valve events of the engine based on the adjusted intake valve wrap angle and valve overlap angle comprises: acquiring the exhaust pollutant content and/or the exhaust catalyst inlet temperature corresponding to the inlet valve wrap angle and the valve overlap angle of the engine which are adjusted at preset intervals each time; and comparing the exhaust pollutant content and/or the exhaust catalyst inlet temperature corresponding to the inlet valve wrap angle and the valve overlap angle of the engine which are adjusted at preset intervals each time, determining the inlet valve wrap angle and the valve overlap angle corresponding to the lowest exhaust pollutant content or the lowest exhaust catalyst inlet temperature as the inlet valve wrap angle and the valve overlap angle of the engine, and controlling the actions of an inlet valve and an exhaust valve of the engine.

The control method of the intake valve wrap angle and the valve overlap angle of the engine of the embodiment is applied to the direct injection gasoline engine with an intake CVVL system and a VVT system, the intake CVVL system can realize the continuous adjustment of the intake valve wrap angle between 100 DEG CA and 200 DEG CA, and the control method of the intake valve wrap angle and the valve overlap angle of the engine is preferably applied to the characteristic interval of the engine outside the low speed, for example, the rotation speed threshold interval of the engine is below 1500 rpm.

In the prior art, when the engine is in a low-speed external characteristic range, the control strategy of the engine generally adopts the maximum wrap angle and the lift range, meanwhile, the advanced opening angle of an inlet valve relative to an installation phase is 15-30 CA, the delayed closing angle of an exhaust valve relative to the installation phase is 20-30 CA, and the valve overlap angle is 35-60 CA.

Based on the existing control strategy, because the supercharging pressure of the supercharger is high, the intake pressure is higher than the back pressure of the exhaust, the engine forms a relatively obvious scavenging process at a low-speed external characteristic point, the mixed gas which is not fully combusted in the cylinder is scavenged by the scavenging process, so that the original emission of hydrocarbon and carbon monoxide is higher, and meanwhile, the fresh charge and the mixed gas which is not fully combusted react near a vehicle catalyst to further release heat, and the temperature limit which can be born by the catalyst can be exceeded. In addition, since part of the mixture is discharged by the scavenging process without sufficient combustion, more fuel is required to ensure the load output of the engine, resulting in increased fuel consumption of the engine. Generally speaking, the control strategy of the existing engine is not beneficial to energy conservation and emission reduction of the vehicle, and can reduce the service life of the exhaust catalyst.

On the basis, the inventor provides the control method for the inlet valve wrap angle and the valve overlap angle of the engine for how to set the inlet valve wrap angle and the valve overlap angle so as to reduce the temperature of a catalyst, avoid exceeding the temperature limit value of the catalyst and be beneficial to energy conservation and emission reduction of vehicles.

Specifically, the engine speed is detected, when the engine speed is in the threshold interval, the intake valve wrap angle and the valve overlap angle of the engine are adjusted successively at preset intervals, for example, the intake valve wrap angle is decreased from the maximum intake valve wrap angle of the engine at preset intervals, when the valve overlap angle is adjusted, the intake valve advance angle in the valve overlap angle is decreased from 30 ° CA at preset intervals, and the exhaust valve retard angle in the valve overlap angle is decreased from 30 ° CA at preset intervals.

Through the adjustment, the combination of a plurality of groups of inlet valve wrap angles and valve overlap angles is obtained, the exhaust pollutant content and/or the inlet air temperature of the exhaust catalyst corresponding to each group of inlet valve wrap angles and valve overlap angles are detected, and the inlet valve wrap angles and the valve overlap angles corresponding to the lowest exhaust pollutant content and/or inlet air temperature of the exhaust catalyst are determined as the inlet valve wrap angles and the valve overlap angles of the engine.

In order to reduce the testing workload and obtain a better combination of the wrap angle and the overlap angle of the intake valve, the preset intervals are preferably 5 degrees CA, the maximum reduction of the wrap angle of the intake valve is 15-20 degrees CA, the maximum reduction of the advance angle of the intake valve is 10-15 degrees CA, and the maximum reduction of the delay angle of the intake valve is preferably 5-10 degrees CA.

A specific embodiment of the determination method according to the present invention described above is as follows:

in this embodiment, the engine speed is adjusted to a preset speed threshold interval, which is below 1500 rpm.

a. The intake valve wrap angle was adjusted to 200 ° CA.

a1. Setting an advance angle of an intake valve to be 30 CA, and sequentially measuring the exhaust pollutant content C1-C3 and/or the intake temperature T1-T3 of an exhaust catalyst when a delay closing angle of an exhaust valve is 30 CA, 25 CA and 20 CA;

a2. setting an advance angle of an intake valve to be 25 degrees CA, and sequentially measuring the exhaust pollutant content C4-C6 and/or the intake temperature T4-T6 of an exhaust catalyst when a delay closing angle of an exhaust valve is 30 degrees CA, 25 degrees CA and 20 degrees CA;

a3. setting an advance angle of an intake valve to be 20 CA, and sequentially measuring the exhaust pollutant content C7-C9 and/or the intake temperature T7-T9 of an exhaust catalyst when a delay closing angle of an exhaust valve is 30 CA, 25 CA and 20 CA;

a4. setting an advance angle of an intake valve to be 15 CA, and sequentially measuring the exhaust gas pollutant content C10-C12 and/or the intake temperature T10-T12 of an exhaust catalyst when a late closing angle of an exhaust valve is 30 CA, 25 CA and 20 CA.

b. The intake valve wrap angle was adjusted to 195 ° CA.

And repeating the steps a 1-a 4, and measuring the exhaust pollutant content of the engine C13-C24 and/or the intake temperature of the exhaust catalyst T13-T24.

c. The intake valve wrap angle was adjusted to 190 ° CA.

And repeating the steps a 1-a 4, and measuring the exhaust pollutant content of the engine C25-C36 and/or the intake temperature of the exhaust catalyst T25-T36.

d. The intake valve wrap angle was adjusted to 185 ° CA.

And repeating the steps a 1-a 4, and measuring the exhaust pollutant content of the engine C37-C48 and/or the intake temperature of the exhaust catalyst T37-T48.

e. The intake valve wrap angle is adjusted to 180 ° CA.

And repeating the steps a 1-a 4, and measuring the exhaust pollutant content of the engine C49-C60 and/or the intake temperature of the exhaust catalyst T49-T60.

In the above measurement process, if only C1-C60 were measured, the intake valve wrap angle and the valve overlap angle corresponding to the minimum value of C1-C60 were determined as the intake valve wrap angle and the valve overlap angle of the engine. If only T1-T60 were measured, the intake valve wrap angle, valve overlap angle corresponding to the minimum of T1-T60 would be determined as the intake valve wrap angle and valve overlap angle for the engine. If C1-C60 and T1-T60 are measured simultaneously, the intake valve wrap angle and the valve overlap angle corresponding to the minimum value of C1-C60 are determined as the intake valve wrap angle and the valve overlap angle of the engine, or the intake valve wrap angle and the valve overlap angle corresponding to the minimum value of T1-T60 are determined as the intake valve wrap angle and the valve overlap angle of the engine.

In order to ensure that the supercharger does not surge, the method for controlling the inlet valve wrap angle and the valve overlap angle of the engine preferably further comprises measuring the vibration frequency of the supercharger, so that when the vibration frequency of the supercharger is lower than the surge occurrence frequency of the supercharger, the inlet valve wrap angle and the valve overlap angle corresponding to the lowest exhaust pollutant content or the inlet air temperature of an exhaust catalyst are determined as the inlet valve wrap angle and the valve overlap angle of the engine.

Specifically, for example, when the above-described measurements are made at C1-C60 and/or T1-T60, the detection of the vibration frequency of the supercharger F1-F60 is added, and the intake valve wrap angle and the valve overlap angle corresponding to the minimum value among F1-F60, which is lower than the supercharger surge judgment frequency, C1-C60 or T1-T60 are determined as the intake valve wrap angle and the valve overlap angle of the engine.

In the actual test process, compared with the air inlet temperature of the existing catalyst, the air inlet temperature of the catalyst can be reduced by 80-90 ℃ through the air inlet valve wrap angle and the valve overlap angle determined by the determining method, and the oil consumption of an engine can be reduced by 20-25 g/kwh.

Example two

The embodiment relates to a control method of an engine intake valve wrap angle and a valve overlap angle, which has the same steps as the scheme of the first embodiment, and the difference lies in that: in this embodiment, the controlling the intake and exhaust valve actions of the engine according to the adjusted intake valve wrap angle and valve overlap angle comprises: acquiring the exhaust pollutant content and/or the exhaust catalyst inlet temperature corresponding to the inlet valve wrap angle and the valve overlap angle of the engine which are adjusted at preset intervals each time; and when the exhaust pollutant content or the intake temperature of the exhaust catalyst meets a preset condition, controlling the actions of an intake valve and an exhaust valve of the engine according to the adjusted intake valve wrap angle and valve overlap angle of the engine.

Namely, values satisfying the preset exhaust gas pollutant content and/or the preset exhaust gas catalyst intake temperature are selected from the measurement results C1-C60 and/or T1-T60, and the intake valve wrap angle and the valve overlap angle corresponding to the values are determined as the intake valve wrap angle and the valve overlap angle of the engine.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.