CN107654284B - Gasoline engine cooling water high temperature protection system and its control method - Google Patents

Abstract

The invention discloses a gasoline engine cooling water high temperature protection system and a control method thereof, comprising an engine management system, a cooling water temperature sensor, a vehicle speed sensor, an air intake temperature sensor and an atmospheric pressure sensor, a cooling water temperature sensor, a vehicle speed sensor, The signal output terminals of the air intake temperature sensor and the atmospheric pressure sensor are respectively connected with the engine management system, and the signal output terminals of the engine management system are respectively connected with the air conditioning control system, thermostat, cooling fan, heat dissipation device and electronically controlled fuel injection through the control unit. Actuator connection for ignition system. When the temperature of the cooling water is high, the present invention can dissipate heat to the greatest extent and reduce engine heat generation, so that the cooling water can be cooled quickly and timely, and then the engine system can be protected in time before the alarm, the hidden dangers of the oil supply system and the ignition system can be reduced, and the deterioration of the engine oil can be avoided. and the occurrence of knocking.

Description

Gasoline engine cooling water high temperature protection system and its control method

technical field

The invention relates to auto parts, in particular to a gasoline engine cooling water high temperature protection system and a control method thereof.

Background technique

Excessive engine cooling water temperature will cause the oil supply system and ignition system not to work normally, causing oil deterioration and knocking, etc., which will bring great harm to the engine. When the traditional engine coolant temperature is too high, the purpose of warning the driver is achieved by displaying or warning the engine temperature on the instrument is too high. However, this method often leads to insufficient cooling of the cooling water, and there are hidden dangers. In order to reduce the engine cooling water temperature as quickly as possible, how to protect the cooling water high temperature before the high temperature alarm of the cooling water temperature has become a technical problem to be solved urgently.

Contents of the invention

The purpose of the present invention is to provide a gasoline engine cooling water high temperature protection system and its control method. The system can perform cooling water high temperature protection before the cooling water temperature high temperature alarm, and then cool down in time.

In order to achieve the above object, the technical solution adopted by the present invention is: a gasoline engine cooling water high temperature protection system, including an engine management system, and also includes a cooling water temperature sensor, a vehicle speed sensor, an air intake temperature sensor and an atmospheric pressure sensor. The signal output terminals of the water temperature sensor, the vehicle speed sensor, the atmospheric air intake temperature sensor and the atmospheric pressure sensor are respectively connected to the engine management system, and the signal output terminals of the engine management system are respectively connected to the air conditioner through the control unit. The control system, thermostat, cooling fan, heat dissipation device and the execution end connection of the electronically controlled fuel injection ignition system.

Further, an atmospheric pressure sensor is also included, and the signal output end of the atmospheric pressure sensor is connected with the engine management system.

A method for controlling the high temperature protection system of the gasoline engine cooling water, comprising the following steps:

1) When the cooling water temperature sensor measures 105°C < cooling water temperature ≤ 108°C, the engine cooling system enters the high temperature protection mode S, and the engine management system instructs the cooling fan and cooling devices to work at maximum power:

a. The electronic thermostat works at the maximum power;

b. Turn on the cooling fan for ≥10 seconds;

c. The cooling device works at the maximum power;

2) When the cooling water temperature sensor measures 108°C < cooling water temperature ≤ 112, the engine cooling system enters high temperature protection mode M:

a. The electronic thermostat works at the maximum power;

b. Turn on the cooling fan for ≥20 seconds;

c. The cooling device works at the maximum power;

d. Turn off the air conditioning control system;

3) When the cooling water temperature measured by the cooling water temperature sensor is >112°C, the engine cooling system enters the high temperature protection mode L:

a. The electronic thermostat works at the maximum power;

b. Turn on the cooling fan for ≥20 seconds;

c. The cooling device works at the maximum power;

d. Turn off the air conditioning control system to reduce the heat generated by the engine;

e. According to the cooling water temperature measured by the cooling water temperature sensor, the vehicle speed measured by the vehicle speed sensor, the air intake temperature measured by the air intake temperature sensor, the engine speed and the engine load, the cooling water temperature change rate is estimated, and then according to the cooling The rate of change of water temperature reduces the fuel injection pulse width of the electronically controlled fuel injection ignition system and delays the ignition advance angle, reducing the heat generated by the engine.

Further, in e of said step 3), the cooling water temperature change rate estimation method includes the following steps:

1) Calculate the heat Q _IncEng (tt _i ) increased by the engine during the time period (tt _i ) by the following formula:

Among them: Q _Com is the total energy produced by combustion; Q _W is the energy required by the flywheel end to do work;

R _{ActiveCylinerRatio} ＝N _NoFuelCut /N _AllCylinders , that is: the current number of non-fuel-cut cylinders divided by the number of all engine cylinders; V _Displacement is the engine displacement; _{ρEnergyDensity} ＝C _{FuelHeatValue} ×Rho×r(stoichiometricRatio), C _{FuelHeatValue} is the calorific value of fuel , Rho is the intake air density, the value range is 0-3000mgpl, r(stoichiometricRatio) is the ideal air-fuel ratio; n is the engine speed, the value range is 0-6000rpm; f _{CombustionEnergy} (n, Rho) is the The total combustion energy coefficient of the engine obtained by air density calibration; r(1/ _Lambda )×f _TorqueEnergy (n, Rho) is the engine output torque energy coefficient obtained according to the air-fuel ratio Lambda, engine speed n and intake air density;

2) Calculate the heat Q _DecEng (tt _i ) emitted by the engine within the time period (tt _i ) according to the following formula: Q _DecEng (tt _i )≈K(T _C -T _a )A _e

Among them, K is the heat dissipation coefficient, the value range is 0~20; A _e is the heat dissipation area, the value range is 0~2㎡; T _C is the water temperature, the value range is -60℃～130℃; T _a is the atmosphere Temperature, the value range is -60～80℃.

3) Calculate the cooling water temperature change rate dT _c from the following two formulas:

From ΔQ _Eng (tt _i )=K _c ×dT _c ×m _c and ΔQ _Eng (tt _i )=Q _IncEng (tt _i )-Q _DecEng (tt _i )

Then dT _c =ΔQ _Eng (tt _i )/(K _c ×m _c )

Among them, K _c is the specific heat capacity of engine cooling water; m _c is the mass of engine cooling water; _{ΔQ Eng (} tt _{i )} is the change of engine heat; Heat; Q _DecEng (tt _i ) is the heat emitted by the engine during the (tt _i ) time period.

Further, in the e of said step 3), the method for determining to reduce the fuel injection pulse width and retard the ignition advance angle includes the following steps:

1) When the cooling water temperature is higher than 112°C and the water temperature change rate is lower than 1°C/s, the fuel injection pulse width is reduced by 2%, and the ignition advance angle is delayed by 1°C;

2) When the cooling water temperature is higher than 112°C and the water temperature change rate is higher than 1°C/s, the fuel injection pulse width is reduced by 5%, and the ignition advance angle is delayed by 4°C;

3) When the cooling water temperature is higher than 115°C and the water temperature change rate is lower than 1°C/s, the fuel injection pulse width is reduced by 6%, and the ignition advance angle is delayed by 6°C;

4) When the cooling water temperature is higher than 115°C and the water temperature change rate is higher than 1°C/s, the fuel injection pulse width is reduced by 10%, and the ignition advance angle is delayed by 10°C.

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

First, in order to reduce the cooling water temperature of the engine as quickly as possible, before the high temperature alarm of the cooling water temperature, the system protects the high temperature of the cooling water in two ways. Thermostat, high and low speed cooling fans, other heat dissipation devices, such as: electronic water pump, etc.) work at the maximum safe power; the second is to reduce the heat generation capacity of the engine, forcibly close the clutch switch of the air conditioner compressor, and estimate the cooling according to the current working conditions and related sensor signals Change rate of water temperature, reduce fuel injection pulse width, delay ignition advance angle.

Second, in the present invention, the engine management system EMS receives the water temperature signal through the hard wire water temperature sensor. If the EMS system detects that the water temperature is higher, 1) turn off the air conditioning control system, turn on all cooling fans, and turn on the thermostat under the maximum safe power Opening, and use other cooling devices at maximum power; 2) Estimate the water temperature change trend based on the current water temperature and working condition information such as engine load, speed, vehicle speed, and atmospheric temperature; 3) According to the current water temperature and the estimated water temperature change , reducing the fuel injection quantity and delaying the ignition advance angle (thereby reducing the ignition efficiency) to different degrees, and reducing the engine calorific value.

Third, when the temperature of the cooling water is high (higher than 105°C), the present invention can dissipate heat to the greatest extent and reduce engine heating, so that the cooling water can be cooled quickly and in time, and then the engine system can be protected in time before the alarm and the oil supply can be reduced. System and ignition system hidden dangers, to avoid oil deterioration and knocking.

Description of drawings

Figure 1 is a structural schematic diagram of a gasoline engine cooling water high temperature protection system.

Figure 2 is a control flow chart of a gasoline engine cooling water high temperature protection system.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings to facilitate a clearer understanding of the present invention, but they do not limit the present invention.

Gasoline engine cooling water high temperature protection system as shown in Figure 1, comprises engine management system 1 (EMS), cooling water temperature sensor 2, vehicle speed sensor 5, air intake air temperature sensor 4 and atmospheric pressure sensor 3, described cooling water temperature sensor 2. The signal output terminals of the vehicle speed sensor 5, the atmospheric air intake temperature sensor 4 and the atmospheric pressure sensor 3 are respectively connected to the engine management system 1, and the signal output terminals of the engine management system 1 are connected through the control unit They are respectively connected with the execution ends of the air conditioning control system 6, the thermostat 7, the cooling fan 8, other heat dissipation devices 10 and the electronically controlled fuel injection ignition system 9. The engine management system 1 communicates with the cooling water temperature sensor 2, thermostat 7, cooling fan 8, electronically controlled fuel injection ignition system 9, and air intake temperature sensor 4 through hard wires. The cooling water temperature sensor 2 is used to detect engine cooling. Water temperature; the engine management system 1 also communicates with the vehicle speed sensor 5, the air conditioning control system 6 and other cooling devices 10 (electronic water pumps, etc.) through hard wires or CAN wires.

The control process of the above gasoline engine cooling water high temperature protection system is shown in Figure 2. The engine management system receives the cooling water temperature signal, vehicle speed signal, air intake temperature, engine speed, and engine load signal, and determines different cooling water protection modes according to different signal values. :

1) When the cooling water temperature is lower than 105°C, the engine management system EMS maintains the original strategy to control the engine temperature, that is, it does not enter the system protection mode.

2) When the cooling water temperature is higher than 105°C, the engine management system EMS works on the engine cooling parts at maximum power and enters the system protection mode S:

a. Ensure that the maximum power of the electronic thermostat works, but it cannot exceed its maximum allowable power;

b. Turn on the high and low speed cooling fan. Once the fan is turned on, the enabling time must not be less than 10 seconds to reduce the switching frequency of the fan, improve the life of the fan, and reduce noise at the same time;

c. Ensure that other heat dissipation devices (such as electronic water pumps, etc.) work at the maximum power, but cannot exceed their maximum allowable power.

3) When the cooling water temperature is higher than 108°C, the engine cooling system enters the protection mode M, namely:

a. Ensure that the maximum power of the electronic thermostat works, but it cannot exceed its maximum allowable power;

b. Turn on the high and low speed cooling fan. Once the fan is turned on, the enabling time should not be less than 20 seconds to reduce the switching frequency of the fan, improve the life of the fan, and reduce noise at the same time;

c. Ensure that other heat dissipation devices (such as electronic water pumps, etc.) work at the maximum power, but cannot exceed their maximum allowable power;

d. The engine management system requests to turn off the air conditioning control system to reduce the heat generated by the engine.

4) When the cooling water temperature is higher than 112°C, the engine cooling system enters the protection mode L, namely:

a. Ensure that the maximum power of the electronic thermostat works, but it cannot exceed its maximum allowable power;

b. Turn on the high and low cooling fans. Once the fan is turned on, the enabling time must not be less than 20 seconds to reduce the switching frequency of the fan, improve the life of the fan, and reduce noise at the same time;

c. Ensure that other heat dissipation devices (such as electronic water pumps, etc.) work at the maximum power, but cannot exceed their maximum allowable power;

d. The engine management system requests to turn off the air conditioning control system to reduce the heat generated by the engine;

e. According to the cooling water temperature, engine speed (calculated by the engine management system), engine load (engine load refers to the intake air density, that is: the air density entering the cylinder, obtained by dividing the air mass entering the cylinder by the cylinder volume ), vehicle speed and atmospheric air intake temperature to estimate the cooling water temperature change rate, thereby reducing the fuel injection pulse width and delaying the ignition advance angle to different degrees, and reducing the engine calorific value, because the smaller the fuel injection volume, that is: the engine The smaller the amount of fuel burned, the smaller the heat released by combustion, the lower the engine calorific value, the lower the cooling water temperature rise rate or the lower water temperature; delaying the ignition angle, the lower the engine ignition efficiency, will inevitably reduce the cooling water temperature.

Among them, the cooling water temperature change rate estimation method is as follows:

1) Calculating the heat Q _IncEng (tt _i ) increased by the engine during the time period (tt _i ), the heat increased by the engine is equal to the energy produced by combustion minus the energy required for work at the flywheel end:

Wherein: Q _Com is the total energy produced by combustion; Q _W is the energy needed for the flywheel end to do work; R _{ActiveCylinerRatio} =N _NoFuelCut /N _AllCylinders , that is: the current non-oil-cut cylinder number is divided by all cylinder numbers of the engine (in this embodiment, N _NoFuelCut ranges from 0 to 3, N _AllCylinders is equal to 3); V _Displacement is the engine displacement (V _Displacement is equal to 1.0 in the system of the present invention); ρ _{EnergyDensity} = C _{FuelHeatValue} × Rho × r (stoichiometricRatio), C _{FuelHeatValue} is the calorific value of fuel , Rho is the intake air density, the value range is 0-3000mgpl, r(stoichiometricRatio) is the ideal air-fuel ratio, equal to 14.3; n is the engine speed, the value range is 0-6000rpm; f _{CombustionEnergy} (n, Rho) is the engine speed The total combustion energy coefficient of the engine obtained by calibration with the intake air density; r(1 _Lambda )×f _TorqueEnergy (n,Rho) is the engine output torque energy coefficient obtained according to the air-fuel ratio Lambda, engine speed n and intake air density; r(1 _Lambda ) is the coefficient calibrated according to the air-fuel ratio Lambda; _{fTorqueEnergy} (n, Rho) is the energy coefficient corresponding to the flywheel end torque calibrated according to the engine speed and intake air density. The above-mentioned calibrations are all obtained through bench calibration (in the bench, firstly, by fixing the Lambda at the ideal air-fuel ratio, then performing bench calibration at different engine speeds, changing the intake air density, and performing bench calibration; then performing bench calibration in different air fuel ratio, compensation).

2) Calculate the heat Q _DecEng (tt _i ) emitted by the engine during the time period (tt _i ) according to the following formula. After the engine is warmed up, it will continue to dissipate heat to the surrounding environment. Atmospheric temperature, atmospheric pressure and vehicle speed can all reflect the heat dissipation capacity of the engine: Q _DecEng (tt _i )≈K(T _C -T _a )A _e

Among them, K is the heat dissipation coefficient, the value range is 0~20; A _e is the heat dissipation area, the value range is 0~2㎡; T _C is the water temperature, the value range is -60℃～130℃; T _a is the atmosphere Temperature, the value range is -60～80℃.

3) Calculate the cooling water temperature change rate dT _c from the following two formulas:

From ΔQ _Eng (tt _i )=K _c ×dT _c ×m _c and ΔQ _Eng (tt _i )=Q _IncEng (tt _i )-Q _DecEng (tt _i )

Then dT _c =ΔQ _Eng (tt _i )/(K _c ×m _c )

Among them, K _c is the specific heat capacity of engine cooling water; m _c is the mass of engine cooling water; _{ΔQ Eng (} tt _{i )} is the change of engine heat; Heat; Q _DecEng (tt _i ) is the heat emitted by the engine during the (tt _i ) time period.

In addition, the method to determine the reduction of the fuel injection pulse width and delay the ignition advance angle is as follows:

1) When the cooling water temperature is higher than 112°C and the water temperature change rate is lower than 1°C/s, the fuel injection pulse width is reduced by 2%, and the ignition advance angle is delayed by 1°C;

2) When the cooling water temperature is higher than 112°C and the water temperature change rate is higher than 1°C/s, the fuel injection pulse width is reduced by 5%, and the ignition advance angle is delayed by 4°C;

3) When the cooling water temperature is higher than 115°C and the water temperature change rate is lower than 1°C/s, the fuel injection pulse width is reduced by 6%, and the ignition advance angle is delayed by 6°C;

4) When the cooling water temperature is higher than 115°C and the water temperature change rate is higher than 1°C/s, the fuel injection pulse width is reduced by 10%, and the ignition advance angle is delayed by 10°C.

When the fuel injection pulse width and ignition advance angle change due to high water temperature, the transition is smoothed through first-order low-pass filtering. This system can dissipate heat to the greatest extent when the cooling water temperature is high, and reduce engine heat generation, thereby protecting the engine system.

Claims (4)

1. a kind of control method of gasoline engine cooling water high temperature protection system, the gasoline engine cooling water high temperature protection system include Engine management system (1) further includes cooling-water temperature sensor (2), vehicle speed sensor (5) and atmosphere intake air temperature sensor (4), the cooling-water temperature sensor (2), the vehicle speed sensor (5) and the atmosphere intake air temperature sensor (4) letter Number output end is connect with the engine management system (1) respectively, and the signal output end of the engine management system (1) passes through Control unit respectively with air-conditioner control system (6), thermostat (7), cooling fan (8), radiating element (10) and electronic control injection point The actuating station of fiery system (9) connects；

It is characterized by: the control method of the gasoline engine cooling water high temperature protection system, comprising the following steps:

1) when cooling-water temperature sensor measures 105 DEG C of cooling water temperature≤108 DEG C <, engine-cooling system enters high temperature Protected mode S, engine management system instruction cooling fan and radiating element are worked with maximum power:

A, electronic thermostat is worked with maximum power；

B, cooling fan, opening time >=10 second are opened；

C, radiating element is worked with maximum power；

2) when cooling-water temperature sensor measures 108 DEG C of < cooling water temperatures≤112, engine-cooling system enters high temperature dwell Shield mode M:

A, electronic thermostat is worked with maximum power；

B, cooling fan, opening time >=20 second are opened；

C, radiating element is worked with maximum power；

D, air-conditioner control system is closed；

3) when 112 DEG C of the cooling water temperature > that cooling-water temperature sensor measures, engine-cooling system enters high temperature protection Mode L:

A, electronic thermostat is worked with maximum power；

B, cooling fan, opening time >=20 second are opened；

C, radiating element is worked with maximum power；

D, air-conditioner control system is closed, to reduce engine calorific value；

E, speed, the atmosphere intake air temperature that the cooling water temperature that is measured according to cooling-water temperature sensor, vehicle speed sensor measure Atmosphere intake air temperature, engine speed and the engine load that sensor measures estimate cooling water temperature change rate, and then basis Cooling water temperature change rate reduces the fuel injection pulsewidth of electronic control injection ignition system and postpones ignition advance angle, reduces engine fever Amount.

2. the control method of gasoline engine cooling water high temperature protection system according to claim 1, it is characterised in that: further include big The signal output end of air pressure force snesor (3), the barometric pressure sensor (3) is connect with the engine management system (1).

3. the control method of gasoline engine cooling water high temperature protection system according to claim 1, it is characterised in that: the step 3) in e, cooling water temperature change rate predictor method the following steps are included:

1) (t-t is calculated by following formula_i) the increased heat Q of period intrinsic motivation_IncEng(t-t_i):

Wherein: Q_ComThe gross energy generated for burning；Q_WThe energy needed for flywheel end acting；

R_{ActiveCylinerRatio}=N_NoFuelCut/N_AllCylinders, it may be assumed that current non-oil-break number of cylinders is divided by all cylinder numbers of engine； V_DisplacementFor engine displacement；ρ_{EnergyDensity}=C_{FuelHeatValue}× Rho × r (stoichiometricRatio), C_{FuelHeatValue}For fuel oil calorific value, Rho is density of the induced air, value range 0~3000mgpl, r (stoichiometricRatio) For ideal air-fuel ratio；N is engine speed, and value range is 0~6000rpm；f_{CombustionEnergy}(n, Rho) is according to hair Motivation revolving speed and the total burning capacity coefficient of density of the induced air engine obtained by calibrating；r(1/_Lambda)×f_TorqueEnergy(n,Rho) To obtain engine output torque energy coefficient according to air-fuel ratio Lambda, engine speed n and density of the induced air；

2) (t-t is calculated according to the following formula_i) the heat Q that distributes of period intrinsic motivation_DecEng(t-t_i): Q_DecEng(t-t_i)≈K(T_C- T_a)A_e

Wherein, K is coefficient of heat transfer, and value range is 0~20；A_eFor heat dissipation area, value range is 0~2 ㎡；T_CFor water temperature, take Being worth range is -60 DEG C~130 DEG C；T_aFor atmospheric temperature, value range is -60~80 DEG C；

3) cooling water temperature change rate dT is calculated by following two formula_c:

By Δ Q_Eng(t-t_i)=K_c×dT_c×m_cWith Δ Q_Eng(t-t_i)=Q_IncEng(t-t_i)-Q_DecEng(t-t_i)

DT can be obtained_c=Δ Q_Eng(t-t_i)/(K_c×m_c)

Wherein, K_cFor the specific heat capacity of engine cooling water；m_cFor the quality of engine cooling water；ΔQ_Eng(t-t_i) it is engine thermal The variable quantity of amount；Q_IncEng(t-t_i) it is (t-t_i) the increased heat of period intrinsic motivation；Q_DecEng(t-t_i) it is (t-t_i) time The heat that section intrinsic motivation distributes.

4. wanting the control method of the 1 or 3 gasoline engine cooling water high temperature protection systems according to right, it is characterised in that: the step In rapid e 3), determine that the method for reducing fuel injection pulsewidth and postponing ignition advance angle includes the following steps:

1) when cooling water temperature is higher than 112 DEG C, and water temperature change rate is lower than 1 DEG C/s, fuel injection pulsewidth reduces 2%, ignition advance angle Postpone 1 DEG C；

2) when cooling water temperature is higher than 112 DEG C, and water temperature change rate is higher than 1 DEG C/s, fuel injection pulsewidth reduces 5%, ignition advance angle Postpone 4 DEG C；

3) when cooling water temperature is higher than 115 DEG C, and water temperature change rate is lower than 1 DEG C/s, fuel injection pulsewidth reduces 6%, ignition advance angle Postpone 6 DEG C；

4) when cooling water temperature is higher than 115 DEG C, and water temperature change rate is higher than 1 DEG C/s, fuel injection pulsewidth reduces 10%, ignition advance angle Postpone 10 DEG C.