A control method, system, and vehicle for limiting maximum crankshaft torque of an engine
By collecting and calculating sensor signals, and combining engine combustion and lost torque, the amount of fuel injection and the ignition advance angle are controlled, which solves the problem of the lack of limit on the maximum crankshaft torque of the engine in the existing technology, and realizes the protection of the engine and vehicle components.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- DONGFENG MOTOR GRP
- Filing Date
- 2023-12-06
- Publication Date
- 2026-07-21
Smart Images
Figure CN117759450B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of vehicle engine torque control technology, specifically to a control method, system, and vehicle for limiting the maximum crankshaft torque of an engine. Background Technology
[0002] The primary task of the Engine Management System (EMS) is to regulate the engine's output torque by controlling all functions and parameters of the various engine management subsystems that affect torque generation. These engine management subsystems mainly include: the cylinder charge control subsystem, which primarily determines the required intake air quality and adjusts the throttle opening accordingly; the mixture formation subsystem, which primarily calculates the instantaneous fuel quantity and adjusts the injection duration and optimal injection timing accordingly; and the ignition subsystem, which controls the ignition advance angle to approach the ideal ignition advance angle.
[0003] With technological advancements and increasingly higher consumer demands for product performance, the primary task of engine management systems is no longer limited to basic functions. To improve vehicle safety and extend the lifespan of the engine and transmission components, controlling the engine's maximum crankshaft torque is of greater significance.
[0004] Existing engine torque control schemes typically do not effectively limit the maximum crankshaft torque of the engine. During engine operation, excessive crankshaft torque can damage engine mechanical components and vehicle mechanical transmission components. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to provide a control method for limiting the maximum crankshaft torque of an engine, which can accurately and efficiently determine the real-time crankshaft torque of the engine and limit it in a timely manner, thereby effectively avoiding the impact of excessive crankshaft torque on engine components.
[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:
[0007] A control method for limiting the maximum crankshaft torque of an engine includes the following control strategy:
[0008] S1 collects engine intake manifold pressure and temperature signals, engine exhaust port pressure signals, and engine speed signals through sensors;
[0009] S2, Based on the signals collected by the sensors and combined with the engine cylinder information, calculate and determine the intake valve airflow.
[0010] S3 determines the combustion efficiency based on engine speed, intake manifold pressure, and engine cylinder volumetric efficiency.
[0011] S4, calculate and determine the engine combustion torque based on the intake valve airflow and combustion efficiency;
[0012] S5, obtains the current friction loss torque and pumping loss torque of the engine;
[0013] S6, calculate and determine the real-time crankshaft torque of the engine based on the engine combustion torque, friction loss torque and pumping loss torque;
[0014] S7, compare the real-time crankshaft torque with the maximum permissible crankshaft torque designed for the engine, and perform engine crankshaft torque limit control.
[0015] Preferably, the pressure signal value P and temperature signal value TK of the engine intake manifold are obtained by pressure and temperature sensors installed in the intake manifold, the pressure signal value P2 of the engine exhaust port is obtained by pressure sensor installed in the engine exhaust port, and the engine speed signal value n is obtained by position sensor installed in the camshaft.
[0016] Preferably, the formula for calculating the intake valve airflow is as follows:
[0017] ValveFlow=n*P*m*V*VE*η / (R*TK)
[0018] In the formula, R is the gas constant, V is the displacement of each cylinder of the engine, m is the number of cylinders of the engine, VE is the cylinder volumetric efficiency, and is a constant coefficient that converts engine speed into 1000 times the number of cycles per second.
[0019] Preferably, determining the combustion efficiency specifically includes: determining a basic combustion efficiency by consulting an experience table of combustion efficiency based on engine speed, intake manifold pressure, and engine cylinder volumetric efficiency; and then correcting the basic combustion efficiency by combining laboratory combustion efficiency test calibration data to obtain the final combustion efficiency.
[0020] Preferably, the formula for calculating the engine combustion torque CT is as follows:
[0021] CT=ValveFlow*FAR*FHV*1000*CE / (n*2*π / 60)
[0022] In the formula, FAR is the stoichiometric fuel-air ratio, and FHV is the lower calorific value of gasoline fuel.
[0023] Preferably, the current friction loss torque of the engine is obtained by calibrating a lookup table using an engine bench test, and the pumping loss torque is obtained by looking up an empirical table of pumping loss torque based on the engine intake pressure, exhaust pressure, intake manifold temperature, intake manifold pressure and engine speed.
[0024] The formula for calculating the real-time crankshaft torque CST of the engine is as follows:
[0025] CST = CT – FAPT
[0026] In the formula, FAPT is the sum of the engine's current friction loss torque and pumping loss torque.
[0027] Preferably, the engine crankshaft torque limiting control specifically includes:
[0028] 1) When the real-time crankshaft torque of the engine exceeds the maximum permissible crankshaft torque designed for the engine, the engine control unit executes a round of torque reduction control:
[0029] Target fuel injection quantity Q0 = 0.5 * Q
[0030] Target intake volume ValveFlow0 = 0.5 * ValveFlow
[0031] Target ignition advance angle W0 = 0.5 * W
[0032] In the formula, Q is the current real-time fuel injection quantity, and W is the current real-time ignition advance angle;
[0033] 2) After executing one round of torque reduction control, re-evaluate whether the real-time crankshaft torque of the engine exceeds the maximum allowable crankshaft torque designed for the engine. If so, continue to execute the next round of torque reduction control; otherwise, exit the torque reduction control.
[0034] Compared with the prior art, the present invention has the following main advantages:
[0035] 1. This invention proposes a control method for limiting the maximum crankshaft torque of an engine. Based on sensor signal acquisition, combined with calculations of engine intake valve airflow, combustion efficiency, engine combustion torque, current friction loss torque and pumping loss torque, and real-time engine crankshaft torque, the real-time crankshaft torque of the engine can be accurately and efficiently determined.
[0036] 2. This invention calculates the engine crankshaft torque and compares it with the maximum permissible crankshaft torque. When the maximum permissible crankshaft torque is exceeded, the engine control unit promptly reduces the engine crankshaft torque by controlling measures such as reducing the amount of fuel injection, reducing the amount of air intake, and reducing the ignition advance angle. This effectively prevents excessive crankshaft torque from damaging the engine's mechanical components and the vehicle's mechanical transmission components. Attached Figure Description
[0037] Figure 1 This is a logic diagram of the control method for limiting the maximum crankshaft torque of an engine in an embodiment of the present invention;
[0038] Figure 2 This is an overall flowchart of the control method for limiting the maximum crankshaft torque of an engine in an embodiment of the present invention. Detailed Implementation
[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.
[0040] It should be noted that, depending on the implementation needs, the various steps / components described in this application can be broken down into more steps / components, or two or more steps / components or parts of the operation of steps / components can be combined into new steps / components to achieve the purpose of this invention.
[0041] Example 1: This example provides a control method for limiting the maximum crankshaft torque of an engine, such as... Figure 1 As shown, the main control strategies include the following:
[0042] 1. Sensor signal acquisition:
[0043] Intake manifold pressure P and temperature signal TK are obtained from the intake manifold pressure and temperature sensor, engine exhaust pressure P2 is obtained from the engine exhaust pressure sensor, and engine speed n is collected from the camshaft position sensor.
[0044] 2. Intake valve airflow calculation:
[0045] Engine speed is n (rpm), engine intake manifold pressure is P (kPa), intake manifold temperature is TK (Kelvin (k)); engine exhaust pressure is P2 (kPa); gas constant is R = 287 J / kg / k; displacement per cylinder is V (m3); number of cylinders is m; cylinder volumetric efficiency is VE. The values are determined by referring to a table based on the engine pressure ratio (engine exhaust pressure (P2) / intake manifold pressure (P)) and engine speed n, and calibrated according to actual engine data. η is a constant, representing a factor of 1000 times the engine speed (rpm) converted to cycles per second; here, it is taken as 8.3. According to the gas state equation, intake valve flow rate = n*P*m*V*VE*η / (R*TK), unit: g / s.
[0046] 3. Combustion efficiency calculation:
[0047] The combustion efficiency CE can be obtained from a table based on the engine speed n, intake manifold pressure P, and volumetric efficiency VE. The specific CE should be calibrated according to the actual situation.
[0048] 4. Engine combustion torque calculation:
[0049] The stoichiometric fuel-air ratio is FAR, typically 0.066667 for gasoline; the lower heating value of the fuel is FHV, typically 43.1 MJ / kg for gasoline; combustion torque is CT; unit: Nm³.
[0050] CT=ValveFlow*FAR*FHV*1000*CE / (n*2*π / 60)
[0051] 5. Calculation of current frictional loss torque and pumping loss torque:
[0052] Frictional loss torque and pumping loss torque (FAPT) can be calibrated using engine bench testing and lookup tables. The values obtained are obtained by looking up the tables using intake pressure, exhaust pressure, intake manifold temperature, intake manifold pressure, and engine speed.
[0053] 6. Engine crankshaft torque (CST) calculation:
[0054] CST = CT – FAPT;
[0055] 7. Limit crankshaft torque
[0056] The calculated engine crankshaft torque is compared with the designed maximum permissible crankshaft torque. If it exceeds the maximum permissible crankshaft torque, the engine control unit needs to promptly reduce the engine crankshaft torque by reducing the amount of fuel injection, reducing the amount of air intake, and reducing the ignition advance angle, so as to prevent excessive crankshaft torque from damaging the engine mechanical components and the mechanical transmission components of the whole vehicle.
[0057] Furthermore, this invention calculates the crankshaft torque of the engine and compares it with the maximum permissible crankshaft torque. If the maximum permissible crankshaft torque is exceeded, the engine control unit needs to promptly reduce the amount of fuel injection, reduce the amount of air intake, and reduce the ignition advance angle to lower the crankshaft torque, so as to prevent excessive crankshaft torque from damaging the engine mechanical components and the mechanical transmission components of the vehicle.
[0058] Example 2: This example provides a control method for limiting the maximum crankshaft torque of an engine, such as... Figure 2 As shown, it includes the following steps:
[0059] S1 collects engine intake manifold pressure and temperature signals, engine exhaust port pressure signals, and engine speed signals through sensors;
[0060] S2, Based on the signals collected by the sensors and combined with the engine cylinder information, calculate and determine the intake valve airflow.
[0061] S3 determines the combustion efficiency based on engine speed, intake manifold pressure, and engine cylinder volumetric efficiency.
[0062] S4, calculate and determine the engine combustion torque based on the intake valve airflow and combustion efficiency;
[0063] S5, obtains the current friction loss torque and pumping loss torque of the engine;
[0064] S6, calculate and determine the real-time crankshaft torque of the engine based on the engine combustion torque, friction loss torque and pumping loss torque;
[0065] S7, compare the real-time crankshaft torque with the maximum permissible crankshaft torque designed for the engine, and perform engine crankshaft torque limit control.
[0066] Furthermore, the pressure signal value P and temperature signal value TK of the engine intake manifold are obtained by pressure and temperature sensors installed in the intake manifold, the pressure signal value P2 of the engine exhaust port is obtained by pressure sensor installed in the engine exhaust port, and the engine speed signal value n is obtained by position sensor installed in the camshaft.
[0067] Furthermore, the formula for calculating the intake valve airflow is as follows:
[0068] ValveFlow=n*P*m*V*VE*η / (R*TK)
[0069] In the formula, R is the gas constant, V is the displacement of each cylinder of the engine, m is the number of cylinders of the engine, VE is the cylinder volumetric efficiency, and is a constant coefficient that converts engine speed into 1000 times the number of cycles per second.
[0070] Furthermore, determining the combustion efficiency specifically includes: determining a basic combustion efficiency by consulting an empirical table of combustion efficiency based on engine speed, intake manifold pressure, and engine cylinder volumetric efficiency; then correcting the basic combustion efficiency by combining laboratory combustion efficiency test calibration data to obtain the final combustion efficiency.
[0071] Furthermore, the calculation formula for the engine combustion torque CT is as follows:
[0072] CT=ValveFlow*FAR*FHV*1000*CE / (n*2*π / 60)
[0073] In the formula, FAR is the stoichiometric fuel-air ratio, and FHV is the lower calorific value of gasoline fuel.
[0074] Furthermore, the current friction loss torque of the engine is obtained by calibrating a lookup table using an engine bench test, and the pumping loss torque is obtained by consulting an empirical table of pumping loss torque based on the engine intake pressure, exhaust pressure, intake manifold temperature, intake manifold pressure and engine speed.
[0075] The formula for calculating the real-time crankshaft torque CST of the engine is as follows:
[0076] CST = CT – FAPT
[0077] In the formula, FAPT is the sum of the engine's current friction loss torque and pumping loss torque.
[0078] Furthermore, the aforementioned engine crankshaft torque limiting control specifically includes:
[0079] 1) When the real-time crankshaft torque of the engine exceeds the maximum permissible crankshaft torque designed for the engine, the engine control unit executes a round of torque reduction control:
[0080] Target fuel injection quantity Q0 = 0.5 * Q
[0081] Target intake volume ValveFlow0 = 0.5 * ValveFlow
[0082] Target ignition advance angle W0 = 0.5 * W
[0083] In the formula, Q is the current real-time fuel injection quantity, and W is the current real-time ignition advance angle;
[0084] 2) After executing one round of torque reduction control, re-evaluate whether the real-time crankshaft torque of the engine exceeds the maximum allowable crankshaft torque designed for the engine. If so, continue to execute the next round of torque reduction control; otherwise, exit the torque reduction control.
[0085] Example 3: Based on the same inventive concept, this example also provides an on-board control system, including a memory, a processor, and a program stored in the memory and executable on the processor. When the processor executes the program, it implements the control method described above for limiting the maximum crankshaft torque of the engine.
[0086] Example 4: Based on the same inventive concept, this example also provides a vehicle with a manual / automatic transmission, wherein the vehicle is equipped with the vehicle control system described above.
[0087] Furthermore, all parts of this application that are not described in detail are the same as or implemented using existing technology.
[0088] In summary:
[0089] 1. This invention proposes a control method for limiting the maximum crankshaft torque of an engine. Based on sensor signal acquisition, combined with calculations of engine intake valve airflow, combustion efficiency, engine combustion torque, current friction loss torque and pumping loss torque, and real-time engine crankshaft torque, the real-time crankshaft torque of the engine can be accurately and efficiently determined.
[0090] 2. This invention calculates the engine crankshaft torque and compares it with the maximum permissible crankshaft torque. When the maximum permissible crankshaft torque is exceeded, the engine control unit promptly reduces the engine crankshaft torque by controlling measures such as reducing the amount of fuel injection, reducing the amount of air intake, and reducing the ignition advance angle. This effectively prevents excessive crankshaft torque from damaging the engine's mechanical components and the vehicle's mechanical transmission components.
[0091] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A control method for limiting the maximum crankshaft torque of an engine, characterized in that, Including the following control strategies: The engine intake manifold pressure and temperature signals, engine exhaust port pressure signals, and engine speed signals are collected by sensors. Based on the signals collected by the sensors and combined with the engine cylinder information, the intake valve airflow is calculated and determined. Combustion efficiency is determined based on engine speed, intake manifold pressure, and engine cylinder volumetric efficiency. The engine combustion torque is calculated and determined based on the intake valve airflow and combustion efficiency. Obtain the current frictional loss torque and pumping loss torque of the engine; The real-time crankshaft torque of the engine is calculated and determined based on the engine combustion torque, friction loss torque, and pumping loss torque. The real-time crankshaft torque is compared with the maximum permissible crankshaft torque designed for the engine to perform engine crankshaft torque limitation control. The aforementioned engine crankshaft torque limiting control specifically includes: When the engine's real-time crankshaft torque exceeds the engine's maximum permissible crankshaft torque, the engine control unit executes a round of torque reduction control: Target fuel injection quantity Q0 = 0.5 * Q Target intake volume ValveFlow0 = 0.5 * ValveFlow Target ignition advance angle W0 = 0.5 * W In the formula, Q is the current real-time fuel injection quantity, ValveFlow is the intake valve airflow, and W is the current real-time ignition advance angle; After executing one round of torque reduction control, the engine's real-time crankshaft torque is reassessed to determine if it exceeds the engine's maximum allowable crankshaft torque. If so, the next round of torque reduction control is executed; otherwise, the torque reduction control is exited.
2. The control method for limiting the maximum crankshaft torque of an engine according to claim 1, characterized in that, The pressure signal value P and temperature signal value TK of the engine intake manifold are obtained by pressure and temperature sensors installed in the intake manifold, the pressure signal value P2 of the engine exhaust port is obtained by pressure sensor installed in the engine exhaust port, and the engine speed signal value n is obtained by position sensor installed in the camshaft.
3. The control method for limiting the maximum crankshaft torque of an engine according to claim 2, characterized in that, The formula for calculating the intake valve airflow is as follows: ValveFlow = n*P*m*V*VE*ŋ / (R*TK) In the formula, R is the gas constant, V is the displacement of each cylinder of the engine, n is the engine speed signal value, P and TK are the pressure signal value and temperature signal value of the engine intake manifold, respectively, m is the number of engine cylinders, VE is the cylinder volumetric efficiency, and ŋ is a constant coefficient that converts engine speed into 1000 times the number of cycles per second.
4. The control method for limiting the maximum crankshaft torque of an engine according to claim 2, characterized in that, The determination of combustion efficiency specifically includes: determining a basic combustion efficiency by consulting an experience table of combustion efficiency based on engine speed, intake manifold pressure, and engine cylinder volumetric efficiency; then correcting the basic combustion efficiency by combining laboratory combustion efficiency test calibration data to obtain the final combustion efficiency.
5. The control method for limiting the maximum crankshaft torque of an engine according to claim 3, characterized in that, The formula for calculating the engine combustion torque CT is as follows: CT = ValveFlow*FAR*FHV*1000*CE / (n*2*π / 60) In the formula, FAR is the stoichiometric fuel-air ratio, FHV is the lower calorific value of gasoline fuel, CE is the combustion efficiency, and n is the engine speed signal value.
6. The control method for limiting the maximum crankshaft torque of an engine according to claim 5, characterized in that, The current friction loss torque of the engine is obtained by calibrating a lookup table using an engine bench test. The pumping loss torque is obtained by looking up an empirical table of pumping loss torque based on the engine intake pressure, exhaust pressure, intake manifold temperature, intake manifold pressure, and engine speed. The formula for calculating the real-time crankshaft torque CST of the engine is as follows: CST = CT – FAPT In the formula, FAPT is the sum of the engine's current friction loss torque and pumping loss torque.
7. A vehicle-mounted control system, comprising a memory, a processor, and a program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the control method for limiting the maximum crankshaft torque of the engine as described in any one of claims 1 to 6.
8. A non-transitory readable storage medium having a program stored thereon, characterized in that, When executed by the vehicle control system, the program implements the control method for limiting the maximum crankshaft torque of the engine as described in any one of claims 1 to 6.
9. A vehicle with both manual and automatic transmissions, characterized in that: Includes the vehicle control system as described in claim 7.