CN114320595A

CN114320595A - Control method for avoiding gasoline engine running in knocking area

Info

Publication number: CN114320595A
Application number: CN202111440555.4A
Authority: CN
Inventors: 黄晓波; 龚贺师; 潘俭栓; 廖善彬; 骆旭薇; 张海滨; 郭华锋; 宁成钢
Original assignee: Jiangling Motors Corp Ltd
Current assignee: Jiangling Motors Corp Ltd
Priority date: 2021-11-30
Filing date: 2021-11-30
Publication date: 2022-04-12
Anticipated expiration: 2041-11-30
Also published as: CN114320595B

Abstract

The invention relates to a control method for avoiding a gasoline engine from operating in a knocking area. Belongs to the technical field of automobile software development and application. The method comprises the following steps: step 1, identifying a knocking area, and judging whether the engine knocks or not according to a cylinder pressure detection mode; step 2, realizing the power demand of the vehicle; and 3, avoiding operation of the detonation zone, namely increasing the rotating speed of the engine on an equal power line of the engine, changing the operating condition point of the engine, and increasing the target rotating speed of the engine to enable the engine to quickly pass through the detonation danger zone with low rotating speed and high load. According to the invention, the gear-shifting curve is corrected to delay the gear-shifting or the speed-reducing ratio, so that the engine rapidly crosses a low-speed high-load knocking area, and the engine is prevented from knocking.

Description

Control method for avoiding gasoline engine running in knocking area

Technical Field

The invention relates to a control method for avoiding a gasoline engine from operating in a knocking area. Belongs to the technical field of automobile software development and application.

Background

Knocking occurred during the test: the vehicle was tested for TASE with an ambient temperature of 38 ℃ and a 30km @12% grade, and the engine would knock more heavily under full load conditions.

When the test driving is carried out, the rotating speed is 1300-1800RPM and is about equal to or larger than 80NM, and obvious continuous knocking sound can be generated with probability; on the actual road of this kind of operating mode: at uniform speeds of more than 70 km, ordinary acceleration is generally used, but the effect of the uniform speed of 70 km is more obvious.

Vehicle starting and rattling: when the vehicle starts, the vehicle hears the sound of the rattling, measures the rough combustion of the engine, and the high pressure rise rate, and causes the sound.

The high-efficiency gasoline engine has the characteristic of high compression ratio, but can generate knocking phenomenon when running at high temperature, low speed and medium and high load. Typically, excessive fuel injection is used to reduce combustion chamber temperature or to use high grade fuel, or to sacrifice efficiency by retarding the firing angle, etc. to reduce the occurrence of knocking and super-knocking, and knocking cannot be completely eliminated.

Disclosure of Invention

The invention aims to solve the technical problem of providing a control method for avoiding the gasoline engine from operating in a knocking area, which delays the gear-up or gear-down ratio by correcting a gear-shifting curve, quickly crosses the low-speed high-load knocking area and avoids the engine from knocking.

The invention discloses a control method for avoiding a gasoline engine from operating in a knocking area, which comprises the following steps of:

step 1, knocking area identification:

judging whether the engine knocks or not according to the cylinder pressure detection mode;

step 2, realizing the power demand of the vehicle;

step 3, avoiding operation of a knocking area:

the engine rotating speed is increased on an equal power line of the engine, the operating condition point of the engine is changed, the target rotating speed of the engine is increased, and the engine can rapidly pass through a low-rotating-speed high-load detonation risk area.

Further, step 1 in the method specifically includes:

identifying the explosion working condition through a software function according to DOE scanning point data of the engine pedestal; whether the software function is activated or not can be realized by judging various conditions and calibrating related data; after the software function is activated, the working condition is judged by identifying parameters such as the rotating speed of the engine, the required torque of the engine, the air inlet temperature of the engine, the water temperature of the engine and the like, and whether the engine can operate in a knocking area or not is judged.

Further, the method for judging the working condition in the method specifically comprises the following steps:

by analyzing the requirement of a driver on the power of a vehicle, the torque which the engine should provide is miist _ w, the current engine rotating speed is nmot, the current power requirement is calculated by a torque rotating speed module of T2P, then the table is looked up by the power and the temperature of an intake manifold, the rotating speed of the engine without knocking on the same power line is obtained by a power _ T _ speed module, and the difference value between the rotating speed and the current rotating speed is an expected TCU (thermal control unit) to adjust the speed ratio so as to adjust the rotating speed difference value of the operating point of the engine; since different intake manifold temperatures may have different knock regions, whether the engine is operating in the knock region is identified by comparing the torque of the engine and the amount of torque that produces knock at different intake manifold temperatures.

Further, step 2 in the method specifically includes:

the speed ratio is adjusted through the CVT, and the rotating speed and the torque of the engine are adjusted.

Further, step 3 in the method specifically includes:

the engine rotating speed is increased on an equal power line of the engine, the operating condition point of the engine is changed, the increased target rotating speed of the engine is sent to the TCU, the TCU corrects a gear shifting curve according to the target rotating speed sent by the EMS, and the engine can quickly pass through a low-rotating-speed high-load detonation danger area by means of delaying gear up-shifting, speed down-shifting and the like.

Further, the speed ratio adjusting process in the method specifically comprises the following steps:

the EMS is an engine control module, the TCU is a CVT gearbox control module, the EMS identifies the operating condition of the engine through the torque of the engine and the rotating speed of the engine according to the power requirement of the vehicle, if the engine operates in a knocking area, the EMS sends a speed regulation request to the TCU, and the TCU adjusts the speed ratio after receiving the request to realize the speed regulation request of the engine.

Compared with the scheme in the prior art, the control method for avoiding the gasoline engine from operating in the knocking area has the following advantages:

after the knock region identification and avoidance strategy is applied, when the ambient temperature is high and the vehicle runs under the working condition of low rotating speed and high load of the engine, the strategy can be automatically activated, and the EMS can request the TCU to adjust the speed ratio, so that the engine runs under the working condition of relatively high rotating speed, and the knock region is avoided. The technology provides safety guarantee for the engine with high heat efficiency and low oil consumption, and effectively controls the knocking phenomenon of the gasoline engine. The knock of the engine is reduced, the vibration of the engine can be reduced, the NVH performance of the engine is improved, the reliability and the durability of the engine are improved, and meanwhile, the service life of the engine is prolonged.

Drawings

FIG. 1 is a graph of in-cylinder pressure data when an engine is knocking;

FIG. 2 is a graph of knock regions at different ambient temperatures;

FIG. 3 is a control strategy flow diagram;

FIG. 4 is a software model of a control algorithm;

FIG. 5 is an engine knock condition identification algorithm;

FIG. 6 is a schematic diagram of a shock absorbing strategy;

FIG. 7 is an engine operating condition adjustment map;

FIG. 8 is an illustration of EMS algorithm body logic;

FIG. 9 is a detailed illustration of an EMS algorithm;

FIG. 10 is a schematic diagram of algorithm effect verification.

Detailed Description

The control algorithm for avoiding the gasoline engine from operating in the knocking area comprises the following steps:

the engine speed is increased on an equal power line of the engine, the operating condition point of the engine is changed, the increased target engine speed (generally higher than the current speed) is sent to the TCU, the TCU corrects a gear shifting curve according to the target speed sent by the EMS, and the engine rapidly crosses a detonation danger area with low speed and high load by means of delaying gear up-shifting, speed down-shifting and the like, so that the engine is prevented from knocking. After the knock region identification and avoidance strategy is applied, when the ambient temperature is high and the vehicle runs under the working condition of low rotating speed and high load of the engine, the strategy can be automatically activated, the EMS can request the TCU to adjust the speed ratio, so that the engine runs under the working condition of relatively high rotating speed, and the knock region is avoided. The technology provides safety guarantee for the engine with high heat efficiency and low oil consumption, and effectively controls the knocking phenomenon of the gasoline engine.

Postpone the upshift or the deceleration ratio through revising the curve of shifting gears, make the engine cross the regional of the detonation of low-speed and high load fast, avoid the engine to produce the detonation, make the engine have longer life, reduced the noise and the vibration of whole car simultaneously, promoted the NVH quality of whole car.

Detecting the pressure of a knocking cylinder;

as can be seen from the cylinder pressure graph of fig. 1, when the engine is operated at 1550rpm, the pressure curve of PCYL _1 is different from the pressure curves of other cylinders, the cylinder pressure of one cylinder is high in rate, and the pressure peak value is relatively high. From the abnormal pressure change, it is indicated that knocking occurred in one cylinder at that time.

Detecting a full-working-condition knocking area;

according to the cylinder pressure detection mode shown in fig. 1, the knocking phenomenon of the engine can be definitely judged, points are swept on a test bed of the engine, all working conditions which can generate the knocking phenomenon are identified, through the sweeping point test of the DOE, the area and the range of the engine which can generate the knocking are changed when the air inlet temperature is different in the full working area, and fig. 2 shows the change condition of the knocking area under different air inlet temperatures.

In FIG. 2, Torque is the Torque at the off-end of the engine mount and Speed is the engine Speed.

Control strategy development of a knock-avoiding region is carried out;

the characteristics of the detonation zone of the engine are clear, whether the engine will operate in the detonation zone or not can be predicted in advance through a software algorithm, the operation state of the engine is recognized in advance, and when the engine operates in the detonation zone, the operation zone is adjusted in time under the condition of meeting the vehicle power requirement, so that the detonation zone is quickly avoided. The policy flow diagram is shown in fig. 3.

To realize the above functions, the following three key problems need to be solved: firstly, identifying an engine knocking area; secondly, the power demand of a driver on the vehicle during driving is ensured; and then how to realize the evasive operation of the knocking region.

Identifying a knocking area;

according to DOE scanning point data of the engine pedestal, knocking can occur when the load is relatively high under different air inlet temperatures and different engine rotating speeds. The method identifies the explosion working condition through software. Whether the function is activated or not can be realized by judging various conditions and calibrating related data. The software model is shown in fig. 4.

After the function is activated, whether the engine operates in a knocking area or not is judged according to relevant operation information of the engine. And judging the working condition by identifying the parameters of the engine speed, the required torque of the engine, the air inlet temperature of the engine, the water temperature of the engine and the like, and judging whether the engine can operate in a knocking area or not. The detailed identification algorithm is shown in fig. 5, by analyzing the requirement of a driver on vehicle power, the torque which the engine should provide is miist _ w, the current engine speed is nmot, the current power requirement is calculated by a torque speed module of T2P in fig. 5, then the table is looked up by power and intake manifold temperature, the engine speed without knocking on the same power line can be obtained by a power _ T _ speed module, and the difference value between the engine speed and the current speed is the expected TCU to adjust the speed ratio so as to adjust the speed difference value (delt _ speed) of the engine operating point. In addition, since different intake manifold temperatures (tars _ w) may have different knock regions, whether the engine is operating in the knock region is identified by comparing the torque of the engine and the magnitude of the torque that generates knocking at different intake manifold temperatures. When the temperature of an intake manifold is less than or equal to 45 ℃, Torque is obtained through an engine Speed look-up table module (Speed _ Torque _ map 1), meanwhile boundary Torque of knocking is obtained after correction of engine water temperature, the knocking boundary is compared with an actual Torque value miist _ w, when the actual value is greater than the boundary value, knock =1 is output to indicate that the engine operates in a knocking area, otherwise, knock =0 is output, and the engine operates in a non-knocking area. Similarly, the boundary and the knocking state of the knocking region at 45-50 ℃ and above 50 ℃ can be identified, and the knocking region of different intake manifolds is shown in FIG. 2. The knock state of the engine is thus identified by the algorithm, while a knock flag signal is emitted.

The power demand of the vehicle is realized;

the power demand of the vehicle comes from an accelerator pedal signal of a driver, and generally, as the driver steps on an accelerator deeply, the output torque of the engine is increased along with the power demand, and the rotating speed of the engine is gradually increased. If the CVT gearbox continuously adjusts the speed ratio, the rotating speed of the engine can be kept unchanged or changed slowly, and the torque can be increased quickly under the condition of keeping the power of the whole vehicle. In order to ensure the power of the vehicle, the relation between torque power and rotating speed is known (the torque T = coefficient K multiplied by the power P/rotating speed n, wherein K is 9549 usually), and the rotating speed and the torque of the engine can be adjusted by adjusting the speed ratio through the CVT under the condition of ensuring the power required by the vehicle. For example, when the vehicle is in a constant speed climbing condition, the vehicle speed is unchanged, and the load is increased continuously. As shown in fig. 6, the original operating curve is shown as a dashed line, and can be adjusted to the operating curve of the solid line as required.

During engine governing, current engine speed, may be in T = 9550P/n [ where P is power (KW) depending on vehicle system torque demand; n is the rotation speed (r/min); t is torque (Nm) ], required power of the vehicle is solved, then the rotating speed of the engine is increased on an equal power line, the torque of the engine is reduced, and the torque requirement of the whole vehicle is met by adjusting the speed ratio through the TCU.

Evasive operation of a knocking area;

the engine rotating speed is increased on an equal power line of the engine, the operating condition point of the engine is changed, the increased target rotating speed (generally higher than the current rotating speed) of the engine is sent to the TCU, the TCU corrects a gear shifting curve according to the target rotating speed sent by the EMS, and the engine quickly passes through a low-rotating-speed high-load detonation danger area by means of delaying gear shifting, reducing the speed ratio and the like, so that the engine is prevented from knocking, and the engine is shown in figure 7.

Overall algorithm model for functional implementation:

EMS is engine control module, and TCU is CVT gearbox control module, and the general strategy is: according to the power requirement of the vehicle, the EMS identifies the operating condition of the engine through the torque and the rotating speed of the engine, if the engine operates in a detonation zone, the EMS sends a speed regulation request to the TCU, and the TCU adjusts the speed ratio after receiving the request to realize the speed regulation request of the engine. The algorithm diagram is shown in fig. 8.

Detailed diagram of internal algorithm of EMS:

when the system recognizes knocking, knock is set to "1", the engine speed adjustment amount delt _ speed is output to the TCU, and the limiting value and the filtering process are performed before the engine speed adjustment amount delt _ speed is output to the TCU. The algorithm is shown in fig. 9.

Verifying the effect of the detonation avoidance software;

the verification of the algorithm effect is shown in fig. 10, the engine rotating speed is increased on an equal power line of the engine, the operating condition point of the engine is changed, then the increased target rotating speed (generally higher than the current rotating speed) of the engine is sent to the TCU, the TCU corrects a gear shifting curve according to the target rotating speed sent by the EMS, and the engine quickly passes through a knocking danger area with low rotating speed and high load in a mode of delaying gear up and gear down, so that the transmitter is prevented from knocking. After the knock region identification and avoidance strategy is applied, when the ambient temperature is high and the vehicle runs under the working condition of low rotating speed and high load of the engine, the strategy can be automatically activated, the EMS can request the TCU to adjust the speed ratio, so that the engine runs under the working condition of relatively high rotating speed, and the knock region is avoided. The technology provides safety guarantee for the engine with high heat efficiency and low oil consumption, and effectively controls the knocking phenomenon of the gasoline engine.

The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solution of the present invention by those skilled in the art should fall within the protection scope defined by the claims of the present invention without departing from the spirit of the present invention.

Claims

1. A control method for avoiding the gasoline engine from operating in a knocking area is characterized in that: the method comprises the following steps:

step 1, knocking area identification:

step 2, realizing the power demand of the vehicle;

step 3, avoiding operation of a knocking area:

2. The control method of avoiding running the gasoline engine in the knocking region according to claim 1, characterized in that: the method comprises the following steps of 1:

3. The control method of avoiding running the gasoline engine in the knocking region according to claim 2, characterized in that: the method for judging the working condition specifically comprises the following steps:

4. The control method of avoiding running the gasoline engine in the knocking region according to claim 1, characterized in that: the method comprises the following steps of 2:

5. The control method of avoiding running the gasoline engine in the knocking region according to claim 1, characterized in that: the method comprises the following specific steps of step 3:

6. The control method of avoiding running the gasoline engine in the knocking region according to claim 5, characterized in that: the speed ratio adjusting process in the method specifically comprises the following steps: