阅读说明：本技术 发动机的控制方法和装置 (Engine control method and device ) 是由 张晓辉 晏双鹤 刘云辉 杨金鹏 王岩 黄松 顾亚松 董清泉 张召 胡宇辰 于 2020-06-03 设计创作，主要内容包括：本发明涉及发动机技术领域,提供一种发动机的控制方法和装置。该方法包括：检测所述发动机的转速和负荷；判断所述发动机的可变气门正时机构是否满足作动条件；在所述可变气门正时机构不满足所述作动条件时,根据所述发动机的转速和负荷,控制减小所述发动机的普通空燃比以得到第一空燃比；控制所述发动机以所述第一空燃比运行。本发明可以提升发动机性能。(The invention relates to the technical field of engines, and provides a control method and a control device of an engine. The method comprises the following steps: detecting the rotating speed and the load of the engine; judging whether a variable valve timing mechanism of the engine meets an actuating condition; controlling to decrease a normal air-fuel ratio of the engine to obtain a first air-fuel ratio according to a rotation speed and a load of the engine when the variable valve timing mechanism does not satisfy the actuation condition; controlling the engine to operate at the first air-fuel ratio. The invention can improve the performance of the engine.)

1. A control method of an engine, characterized by comprising:

detecting the rotating speed and the load of the engine;

judging whether a variable valve timing mechanism of the engine meets an actuating condition;

when the variable valve timing mechanism does not satisfy the actuation condition, reducing a normal air-fuel ratio of the engine to obtain a first air-fuel ratio according to a rotation speed and a load of the engine;

controlling the engine to operate at the first air-fuel ratio.

2. The control method of the engine according to claim 1, characterized in that the actuation conditions include that the engine speed is greater than a speed threshold, that the water temperature is in a water temperature threshold range, that the oil temperature is in an oil temperature threshold range, and that the voltage is in a voltage threshold range, and that the variable valve timing mechanism is failure-free.

3. The control method of an engine according to claim 1, characterized in that after controlling the engine to operate at the first air-fuel ratio, the method further comprises:

detecting knock data of the engine;

and when the knock data can reach the knock condition, controlling to reduce the common ignition advance angle of the engine according to the knock data, and gradually increasing the reduced value of the common ignition advance angle so as to enable the knock data not to reach the knock condition.

4. The control method of an engine according to claim 3, characterized by further comprising:

and when the value of the reduction of the common ignition advance angle is larger than a first threshold value and the knock data can still reach the knock condition, controlling to reduce the air intake amount of the engine according to the value of the reduction of the common ignition advance angle.

5. The control method of an engine according to claim 1, characterized by further comprising:

controlling the engine to operate at the normal air-fuel ratio when the variable valve timing mechanism satisfies the actuation condition.

6. A control device of an engine, characterized by comprising:

a detection unit, a processing unit and a control unit, wherein,

the detection unit is used for detecting the rotating speed and the load of the engine;

the processing unit is configured to:

judging whether a variable valve timing mechanism of the engine meets an actuating condition;

when the variable valve timing mechanism does not satisfy the actuation condition, reducing a normal air-fuel ratio of the engine to obtain a first air-fuel ratio according to a rotation speed and a load of the engine;

the control unit is used for controlling the engine to operate at the first air-fuel ratio.

7. The control apparatus of the engine according to claim 6, characterized in that the actuation conditions include that the engine speed is greater than a speed threshold, that the water temperature is in a water temperature threshold range, that the oil temperature is in an oil temperature threshold range, and that the voltage is in a voltage threshold range, and that the variable valve timing mechanism is failure-free.

8. The control apparatus of an engine according to claim 6, characterized in that, after controlling the engine to operate at the first ignition advance angle and the first air-fuel ratio,

the detection unit is also used for detecting knock data of the engine;

the control unit is further configured to:

and when the knock data can reach the knock condition, controlling to reduce the common ignition advance angle of the engine according to the knock data, and gradually increasing the reduced value of the common ignition advance angle so as to enable the knock data not to reach the knock condition.

9. The control device of an engine according to claim 8, characterized in that the control unit is further configured to:

and when the value of the reduction of the common ignition advance angle is larger than a first threshold value and the knock data can still reach the knock condition, controlling to reduce the air intake amount of the engine according to the value of the reduction of the common ignition advance angle.

10. The control device of an engine according to claim 6, characterized in that the control unit is further configured to:

controlling the engine to operate at the normal air-fuel ratio when the variable valve timing mechanism satisfies the actuation condition.

Technical Field

The invention relates to the technical field of engines, in particular to a control method and a control device of an engine.

Background

The miller engine is a technology that can significantly improve the thermal efficiency by only changing the cam profile and the valve timing position on the basis of the original otto cycle engine, and is gradually becoming a standard technology of the existing gasoline engine.

Generally, a miller cycle engine is used together with high supercharging and high compression ratio technologies, and when a Variable Valve Timing (VVT) mechanism works normally, an effective compression ratio can be reduced by means of closing an intake Valve closing angle in advance, so that the purpose of reducing the knocking tendency is achieved. When the VVT can not be actuated, the VVT is always in a default position, namely an intake valve late closing position, and at the moment, the Miller effect hardly exists, so that the effective compression ratio is relatively high, the low-speed heavy-load knocking tendency is severe, the advance angle of ignition and the performance are limited, the torque output of an engine is greatly limited, and the dynamic property and the drivability of a vehicle are greatly influenced.

Disclosure of Invention

In view of the above, the present invention is directed to a method for controlling an engine to improve engine performance.

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

a control method of an engine, the control method comprising: detecting the rotating speed and the load of the engine; judging whether a variable valve timing mechanism of the engine meets an actuating condition; when the variable valve timing mechanism does not satisfy the actuation condition, reducing a normal air-fuel ratio of the engine to obtain a first air-fuel ratio according to a rotation speed and a load of the engine; controlling the engine to operate at the first air-fuel ratio.

Further, the actuation conditions include that the engine speed is greater than a speed threshold, the water temperature is in a water temperature threshold range, the oil temperature is in an oil temperature threshold range, and the voltage is in a voltage threshold range, and the variable valve timing mechanism is failure-free.

Further, after controlling the engine to operate at the first air-fuel ratio, the method further comprises: detecting knock data of the engine; and when the knock data can reach the knock condition, controlling to reduce the common ignition advance angle of the engine according to the knock data, and gradually increasing the reduced value of the common ignition advance angle so as to enable the knock data not to reach the knock condition.

Further, the method further comprises: and when the value of the reduction of the common ignition advance angle is larger than a first threshold value and the knock data can still reach the knock condition, controlling to reduce the air intake amount of the engine according to the value of the reduction of the common ignition advance angle.

Further, the method further comprises: controlling the engine to operate at the normal air-fuel ratio when the variable valve timing mechanism satisfies the actuation condition.

Compared with the prior art, the control method of the engine has the following advantages:

firstly detecting the rotating speed and the load of the engine, then judging whether a variable valve timing mechanism of the engine meets an actuating condition, then reducing the ordinary air-fuel ratio of the engine according to the rotating speed and the load of the engine to obtain a first air-fuel ratio when the variable valve timing mechanism does not meet the actuating condition, and finally controlling the engine to operate at the first air-fuel ratio. The invention adopts a mode of reducing the air-fuel ratio when the VVT is not actuated, and greatly reduces the temperature in the cylinder when the engine is compressed by utilizing the latent heat of vaporization of fuel oil, thereby reducing the knocking tendency and improving the performance of the engine.

Another objective of the present invention is to provide a control device for an engine to improve the performance of the engine.

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

a control device of an engine, the control device comprising: the device comprises a detection unit, a processing unit and a control unit, wherein the detection unit is used for detecting the rotating speed and the load of the engine; the processing unit is configured to: judging whether a variable valve timing mechanism of the engine meets an actuating condition; when the variable valve timing mechanism does not satisfy the actuation condition, reducing a normal air-fuel ratio of the engine to obtain a first air-fuel ratio according to a rotation speed and a load of the engine; the control unit is used for controlling the engine to operate at the first air-fuel ratio.

Further, the actuation conditions include that the engine speed is greater than a speed threshold, the water temperature is in a water temperature threshold range, the oil temperature is in an oil temperature threshold range, and the voltage is in a voltage threshold range, and the variable valve timing mechanism is failure-free.

Further, the detection unit is further configured to detect knock data of the engine after controlling the engine to operate at the first ignition advance angle and the first air-fuel ratio; the control unit is further configured to: and when the knock data can reach the knock condition, controlling to reduce the common ignition advance angle of the engine according to the knock data, and gradually increasing the reduced value of the common ignition advance angle so as to enable the knock data not to reach the knock condition.

Further, the control unit is further configured to: and when the value of the reduction of the common ignition advance angle is larger than a first threshold value and the knock data can still reach the knock condition, controlling to reduce the air intake amount of the engine according to the value of the reduction of the common ignition advance angle.

Further, the control unit is further configured to: controlling the engine to operate at the normal air-fuel ratio when the variable valve timing mechanism satisfies the actuation condition.

Compared with the prior art, the control device of the engine and the control method of the engine have the same advantages, and are not repeated.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention.

In the drawings:

fig. 1 is a flowchart of a control method of an engine according to an embodiment of the present invention;

FIG. 2 is a flowchart of a method of controlling an engine provided in accordance with another embodiment of the present invention;

FIG. 3 is a flowchart of a method of controlling an engine provided in accordance with another embodiment of the present invention;

fig. 4 is a block diagram of a control device for an engine according to an embodiment of the present invention.

Description of reference numerals:

1 detection unit 2 processing unit

3 control unit

Detailed Description

In addition, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.

The present invention will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.

The engine of the present invention may be a miller engine. The miller cycle is a low temperature cycle that is effective in reducing the tendency of the engine to knock and in improving the thermal efficiency of the engine. The miller cycle is characterized by an effective compression ratio of the engine that is less than the expansion ratio. The mixture is subjected to an expansion process before the start of a compression stroke through an intake early closing (EIVC) strategy, and the mixture is internally cooled so as to reduce the heat load of the engine and reduce the compression work. The EIVC strategy greatly reduces the effective compression ratio of the engine. The engine compression ratio and the expansion ratio are separated, expansion work is increased, and engine knocking is effectively restrained. The miller cycle not only suppresses engine knock but also reduces NOx emissions. Therefore, the Miller cycle has the advantages of reducing the pumping loss of part load, increasing the expansion work, improving the heat efficiency of the engine, reducing the combustion temperature in the cylinder, reducing the thermal load, reducing the NOx emission and the like.

For a miller cycle supercharged engine, the effective compression ratios of the VVT at a default position (when the engine is running, the VVT is at a locked position, generally the latest position corresponding to the opening of an intake valve, or the earliest position of the closing of an exhaust valve) and the VVT at an active position (when the engine is running, the VVT usually leaves the default position to exert the advantage of oil consumption of the VVT engine, and the purpose of optimal oil consumption or performance is achieved by changing the opening and closing time of a valve, and at the moment, the position of the VVT is the active position of the VVT), the temperature and pressure at the end of compression also have a significant difference, so that the difference of knocking tendency is large, and therefore, the control parameters of the VVT at the default position are individually optimized.

Fig. 1 is a flowchart of a control method of an engine according to an embodiment of the present invention. As shown in fig. 1, the control method includes:

step S11, detecting the speed and load of the engine;

specifically, the rotation speed and the load of the engine may be detected by, for example, a rotation speed sensor, a load sensor, and the like.

Step S12, determining whether the variable valve timing mechanism of the engine satisfies an actuation condition;

specifically, the operating conditions may include that the engine has a rotation speed greater than a rotation speed threshold (e.g., a certain value from 600 to 1000 revolutions), a water temperature in a water temperature threshold range (a certain value from 0 ° to 40 ° to a certain value from 100 ° to 120 °), an oil temperature in an oil temperature threshold range (a certain value from 0 ° to 40 ° to a certain value from 120 ° to 140 °), and a voltage in a voltage threshold range (a certain value from 8 to 9V to a certain value from 16 to 18V), and the VVT is free of malfunction. The rotation speed, the water temperature, the oil temperature, and the voltage can be detected by a rotation speed sensor, a temperature sensor, and the like.

Step S13, when the VVT does not satisfy the actuating condition, the ordinary air-fuel ratio of the engine is reduced according to the rotating speed and the load of the engine to obtain a first air-fuel ratio;

specifically, when the engine with the variable valve timing mechanism normally operates, the corresponding ordinary advance angle, the ordinary air-fuel ratio (for example, the ordinary air-fuel ratio is 14.7) and the ordinary intake air amount set according to the engine operating condition are generally set according to the engine operating condition, which is not described in detail herein. When the VVT does not satisfy the above-mentioned actuation condition, and the VVT is located at the default position, the ordinary air-fuel ratio is decreased according to the detected rotation speed and load of the engine, and the specific decrease amount is related to the current rotation speed and load, and can be obtained by pre-calibration (i.e. under different rotation speed and load conditions, knocking of the engine is made as small as possible, so as to obtain the amount of decreasing the ordinary air-fuel ratio), so as to obtain the first air-fuel ratio after the decrease.

Step S14, controlling the engine to operate at the first air-fuel ratio;

specifically, after the first air/fuel ratio is obtained, the engine may be controlled to operate at the first air/fuel ratio to reduce and limit knock.

Step S15, when the variable valve timing mechanism satisfies the actuation condition, controls the engine to operate at the normal air-fuel ratio.

Specifically, if the VVT satisfies the actuation condition, that is, the VVT is located at the active position, it is sufficient to control the engine to operate at the normal air-fuel ratio without adjusting the air-fuel ratio.

In addition, because the difference of heat dissipation capacity between different engines and the difference of cold capacity condition in the charging temperature of the air inlet of the vehicle can cause the possibility of knocking under the condition that the air-fuel ratio is reduced under the same working condition, the invention also provides a method, as shown in fig. 2, which comprises the following steps:

step S21, detecting knock data of the engine;

specifically, the knock data may be knock intensity and knock frequency, and the knock intensity and frequency of the engine may be detected by a knock sensor.

Step S22, judging whether the knock data can reach the knock condition;

specifically, whether the knock intensity is greater than a preset intensity and/or whether the knock frequency is greater than a preset frequency is determined.

Step S23, when the knock data can not reach the knock condition, controlling the engine to operate at the first air-fuel ratio and the common ignition advance angle;

specifically, if the knock intensity is less than or equal to the preset intensity and the knock frequency is less than or equal to the preset frequency, no adjustment is needed at this time, and the engine is controlled to operate at the first air-fuel ratio and the ordinary advance ignition angle.

Step S24, when the knock data can reach the knock condition, according to the knock data, controlling to reduce the common ignition advance angle of the engine and gradually increasing the reduced value of the common ignition advance angle, so that the knock data can not reach the knock condition;

specifically, when the knock intensity is larger than the preset intensity and/or the knock frequency is larger than the preset frequency, it is not sufficient to suppress knocking only by reducing the air-fuel ratio, and therefore, the ordinary advance angle needs to be reduced, and in the embodiment of the present invention, the higher the knock intensity or frequency, the larger the value of reduction of the ordinary advance angle. The value at which the ordinary advance angle is first reduced can be obtained by calibration in advance (making the knocking as small as possible). If the knock intensity is still greater than the preset intensity and/or the knock frequency is still greater than the preset frequency after the ordinary ignition advance angle is reduced, the value of the reduction of the ordinary ignition advance angle needs to be increased until the knock intensity is less than or equal to the preset intensity and the knock frequency is less than or equal to the preset frequency.

Fig. 3 is a flowchart of a control method of an engine according to another embodiment of the present invention. As shown in fig. 3, in the process of reducing the common advance angle, the method comprises the following steps:

step S31, judging whether the value of the reduction of the common ignition advance angle is larger than a first threshold value;

step S32, when the value of the decrease of the common ignition advance angle is larger than a first threshold value, controlling to decrease the air intake quantity of the engine according to the value of the decrease of the common ignition advance angle;

specifically, in the process of increasing the value of the ordinary advance angle decrease, the value of the ordinary advance angle decrease is compared with the first threshold. When the value of the reduction of the common ignition advance angle is larger than the first threshold value, if the knock data can still reach the knock condition, the reduction of the ignition advance angle is not enough to inhibit the knock, and at the moment, the air intake quantity of the engine needs to be reduced, wherein the reduction of the air intake quantity of the engine refers to the maximum air intake quantity corresponding to the engine under the current working condition. The larger the value of the decrease in the ordinary advance angle is, the larger the value of the decrease in the intake air amount of the engine is, and specifically, the ordinary intake air amount may be multiplied by a coefficient smaller than 1 in relation to the magnitude of the value of the decrease in the ordinary advance angle, and the coefficient may be smaller as the value of the decrease in the ordinary advance angle is larger. Likewise, the coefficient may be obtained by calibration in advance (making knocking as small as possible).

Step S33 is a step of controlling the engine to operate with a normal intake air amount when the value of the first ignition advance angle decrease is equal to or less than a first threshold value.

Specifically, when the value of the reduction of the common spark advance is less than or equal to the first threshold, the knock data cannot reach the knock condition, which indicates that the reduction of the spark advance is enough to suppress the knock, and at this time, the engine does not need to be adjusted, so that the engine can still operate with the common intake air amount calibrated by the engine under the current working condition.

The implementation process of the general scheme of the invention comprises the following steps: firstly, when the VVT meets an actuating condition, normal ignition and oil injection can be carried out according to the working condition of an engine; when the VVT does not meet the actuating condition, knocking can be inhibited by adopting a mode of reducing the air-fuel ratio (namely enriched oil injection), and the air inlet and the ignition advance angle are normal; then, if knocking is detected, the ignition advance angle is reduced, and the value of the reduction of the ignition advance angle is gradually increased, so that the knocking is suppressed (the ignition angle is reduced, the oil-gas combustion time can be delayed as much as possible, and the pressure and the temperature of unburned oil-gas are reduced, so that the self-ignition is reduced, so that the knocking is suppressed); if the value of the decrease in the ignition lead angle is too large and knocking still occurs, knocking is finally suppressed by reducing the intake air amount, at which time the air-fuel ratio uses the above-described decreased air-fuel ratio, and the ignition lead angle uses the above-described decreased ignition lead angle (knocking occurring at this time is based on the decreased air-fuel ratio and the decreased ignition lead angle, and therefore it is necessary to continue using the above-described decreased air-fuel ratio and the above-described decreased ignition lead angle to avoid knocking aggravation). According to the invention, different control modes for inhibiting knocking are selected and adopted at a reasonable time according to the knocking condition of the engine, so that the effects of reducing the knocking tendency and improving the performance of the engine are achieved.

Fig. 4 is a block diagram of a control device for an engine according to an embodiment of the present invention. As shown in fig. 4, the control device includes: the system comprises a detection unit 1, a processing unit 2 and a control unit 3, wherein the detection unit 1 is used for detecting the rotating speed and the load of the engine; the processing unit 2 is configured to: judging whether a variable valve timing mechanism of the engine meets an actuating condition; when the variable valve timing mechanism does not satisfy the actuation condition, reducing a normal air-fuel ratio of the engine to obtain a first air-fuel ratio according to a rotation speed and a load of the engine; the control unit 3 is adapted to controlling the engine to operate at the first air/fuel ratio.

Further, the actuation conditions include that the engine speed is greater than a speed threshold, the water temperature is in a water temperature threshold range, the oil temperature is in an oil temperature threshold range, and the voltage is in a voltage threshold range, and the variable valve timing mechanism is failure-free.

Further, the detection unit 1 is also configured to detect knock data of the engine after controlling the engine to operate at the first ignition advance angle and the first air-fuel ratio; the control unit 3 is further configured to: and when the knock data can reach the knock condition, controlling to reduce the common ignition advance angle of the engine according to the knock data, and gradually increasing the reduced value of the common ignition advance angle so as to enable the knock data not to reach the knock condition.

Further, the control unit 3 is further configured to: and when the value of the reduction of the common ignition advance angle is larger than a first threshold value and the knock data can still reach the knock condition, controlling to reduce the air intake amount of the engine according to the value of the reduction of the common ignition advance angle.

Further, the control unit 3 is further configured to: controlling the engine to operate at the normal air-fuel ratio when the variable valve timing mechanism satisfies the actuation condition.

The control device of the engine described above is similar to the embodiment of the control method of the engine described above, and is not described again here.

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.