CN112378667A - Method for detecting clamping stagnation fault of engine thermostat - Google Patents
Method for detecting clamping stagnation fault of engine thermostat Download PDFInfo
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Abstract
The invention discloses a method for detecting the jamming fault of an engine thermostat, which comprises the following steps: acquiring the actual water temperature of an engine; calculating according to a preset engine energy conservation formula to obtain the heat absorbed by the engine cooling liquid; calculating to obtain the water temperature of an engine model based on the heat absorbed by the engine cooling liquid; making a difference between the water temperature of the engine model and the actual water temperature of the engine to generate a temperature difference; it is determined whether a stuck fault has occurred with the engine thermostat based on the temperature difference. Therefore, by adopting the embodiment of the application, the theoretical model water temperature of the engine can be calculated by utilizing energy conservation according to the engine heat balance theory, the model water temperature is compared with the actual water temperature in a difference mode, and the temperature difference is larger than a certain value within a certain time after the engine is started, so that the blocking of the thermostat is judged, the false alarm of the blocking fault of the thermostat of the engine is reduced, and the running stability of the system is improved.
Description
Technical Field
The invention relates to the field of automobile electronic control, in particular to a method for detecting clamping stagnation faults of an engine thermostat.
Background
A vehicle thermostat is an important component mounted in a vehicle, and is provided on a coolant passage between an engine and a radiator. When the engine thermostat is stuck or is not closed tightly, the engine cooling system operates in a large circulation mode, so that the temperature rise of the engine water temperature is slow, energy waste can be caused, and the engine can not operate at the optimal temperature working condition quickly and stably. Therefore, whether the vehicle thermostat works normally directly influences whether the vehicle engine can normally operate.
The method for detecting whether the vehicle thermostat works normally at present comprises the steps of determining water temperature rise of an engine model according to running time after the engine is started and non-idle working condition occupation ratio, and further determining whether the vehicle thermostat breaks down according to the water temperature rise.
Disclosure of Invention
The embodiment of the application provides a method for detecting the clamping stagnation fault of an engine thermostat. The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosed embodiments. This summary is not an extensive overview and is intended to neither identify key/critical elements nor delineate the scope of such embodiments. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.
In a first aspect, an embodiment of the present application provides a method for detecting a stuck fault of an engine thermostat, where the method includes:
acquiring the actual water temperature of an engine;
calculating according to a preset engine energy conservation formula to obtain the heat absorbed by the engine cooling liquid;
calculating to obtain the water temperature of an engine model based on the heat absorbed by the engine cooling liquid;
making a difference between the water temperature of the engine model and the actual water temperature of the engine to generate a temperature difference;
it is determined whether a stuck fault has occurred with the engine thermostat based on the temperature difference.
Optionally, before obtaining the actual water temperature of the engine, the method further includes:
and detecting the actual water temperature of the current engine in real time through a temperature sensor.
Optionally, the step of calculating the heat absorbed by the engine coolant according to a preset engine energy conservation formula includes:
calculating the total power generated by the fuel combustion of the engine;
calculating the total power utilization of the engine, wherein the total power utilization is the sum of the output power of the engine, the heat lost by exhaust, the heat lost in intake air and the residual heat loss of the engine;
and subtracting the total power from the total power by a preset engine energy conservation formula to generate heat absorbed by the engine cooling liquid.
Optionally, calculating the total power emitted by the combustion of fuel by the engine comprises:
acquiring the energizing pulse width, fuel temperature correction and fuel pressure correction of a fuel nozzle of the engine;
calculating to obtain the accumulated mass flow of the fuel oil of the engine through the energizing pulse width of the fuel nozzle, the fuel temperature correction and the fuel pressure correction;
acquiring a fuel model corresponding to the fuel of the engine;
and calculating the total power generated by the combustion of the fuel of the engine according to the accumulated mass flow of the fuel of the engine and the fuel type.
Optionally, calculating an engine model water temperature based on the heat absorbed by the engine coolant includes:
obtaining the flow rate of cooling liquid of an engine, the water temperature when the engine is started and the corresponding specific heat capacity of the cooling liquid;
and calculating according to the heat absorbed by the engine cooling liquid, the flow rate of the cooling liquid, the water temperature at the starting time and the specific heat capacity corresponding to the cooling liquid to generate the water temperature of the engine model.
Optionally, determining whether the engine thermostat has a stuck fault based on the temperature difference includes:
when the temperature difference is greater than or equal to a preset threshold value, the engine thermostat has a clamping stagnation fault;
when the temperature difference is smaller than the preset threshold value, the engine thermostat has no clamping stagnation fault.
Optionally, the preset engine energy conservation formula is as follows:
Pf＝Pe+Pcooling liquid+PExhaust of gases+PInter-cooler+PHeat generation
Wherein, PfTotal power, P, generated for combustion of engine fueleFor the total power output of the engine, PExhaust of gasesPower lost to engine exhaust, PInter-coolerPower lost to cold in the engine intake, PCooling liquidPower lost to engine coolant, PHeat generationIs a residual power loss of the engine.
Optionally, the power lost by the engine exhaust, comprising:
adding the fuel flow and the intake air flow of the current vehicle to generate exhaust flow;
measuring the ambient temperature of the engine and the current exhaust temperature at the outlet of the vehicle supercharger;
calculating specific constant pressure heat capacity of exhaust gas according to fuel combustion components of the engine;
the power lost by the engine exhaust is generated by calculation based on the exhaust flow rate, the ambient temperature of the engine, the supercharger outlet exhaust temperature, and the specific constant pressure heat capacity of the exhaust.
Optionally, the power of the cooling loss in the intake air of the engine comprises:
measuring an intake air flow rate of the engine;
calculating according to the air intake flow, the efficiency of the engine supercharger and the temperature correction of the exhaust inlet of the supercharger to generate the temperature of air before an intercooler;
measuring the outlet temperature of the intercooler by using a sensor;
generating intercooling front air inlet ratio constant pressure heat capacity and intercooling rear air inlet ratio constant pressure heat capacity according to the intercooler front air temperature and the intercooler outlet temperature;
and calculating based on the air intake flow, the air temperature before the intercooler, the outlet temperature of the intercooler, the air intake ratio constant pressure heat capacity before the intercooler and the air intake ratio constant pressure heat capacity after the intercooler to generate the power of the air intake intercooling loss of the engine.
Optionally, the engine residual power loss comprises:
the engine residual power loss is generated by multiplying the preset percentage by the total power emitted by the combustion of fuel by the engine.
The technical scheme provided by the embodiment of the application can have the following beneficial effects:
in the embodiment of the application, the device for detecting the clamping stagnation fault of the engine thermostat firstly obtains the actual water temperature of the engine, then calculates the absorbed heat of the engine cooling liquid according to a preset engine energy conservation formula to obtain the water temperature of an engine model based on the absorbed heat of the engine cooling liquid, then differentiates the water temperature of the engine model with the actual water temperature of the engine to generate a temperature difference, and finally determines whether the clamping stagnation fault occurs in the engine thermostat based on the temperature difference. According to the method and the device, the theoretical model water temperature of the engine can be calculated by utilizing energy conservation according to the engine heat balance theory, the model water temperature is compared with the actual water temperature in a difference mode, and the temperature difference is larger than a certain value within a certain time after the engine is started, so that the blocking of the thermostat is judged, the false alarm of the blocking fault of the thermostat of the engine is reduced, and the running stability of the system is improved.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.
FIG. 1 is a schematic flow chart illustrating a method for detecting an engine thermostat sticking fault according to an embodiment of the present disclosure;
FIG. 2 is a process diagram illustrating an engine thermostat sticking fault detection process provided by an embodiment of the present application;
FIG. 3 is a schematic flow chart of another method for detecting engine thermostat sticking faults according to an embodiment of the present application.
Detailed Description
The following description and the drawings sufficiently illustrate specific embodiments of the invention to enable those skilled in the art to practice them.
It should be understood that the described embodiments are only some embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the invention, as detailed in the appended claims.
In the description of the present invention, it is to be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art. In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.
At present, the mode of detecting whether the vehicle thermostat works normally is to determine the water temperature rise of an engine model according to the operating time of an engine after starting and the non-idle working condition ratio, and further determine whether the vehicle thermostat breaks down according to the water temperature rise. Therefore, the application provides a method for detecting the jamming fault of the engine thermostat, so as to solve the problems in the related art. In the technical scheme provided by the application, because the theoretical model water temperature of the engine can be calculated by utilizing energy conservation according to the engine heat balance theory, the difference comparison is made between the model water temperature and the actual water temperature, and the blocking of the thermostat is judged if the temperature difference is greater than a certain value within a certain time after the engine is started, so that the false alarm of the blocking fault of the thermostat of the engine is reduced, and the running stability of the system is improved. The following detailed description will be made using exemplary embodiments.
The method for detecting the sticking fault of the engine thermostat provided by the embodiment of the application will be described in detail below with reference to fig. 1 to 3.
Referring to fig. 1, a schematic flow chart of a method for detecting a sticking fault of an engine thermostat is provided according to an embodiment of the present application. As shown in fig. 1, the method of the embodiment of the present application may include the following steps:
s101, acquiring the actual water temperature of the engine;
the engine is a device for driving the vehicle to move. The actual water temperature is the current actual water temperature of the engine detected by the temperature sensor in real time.
In a possible implementation manner, when the engine thermostat clamping stagnation fault is detected, the current actual water temperature of the engine is detected in real time through a temperature sensor, and the current actual water temperature of the engine is determined as the actual water temperature of the engine thermostat clamping stagnation fault.
S102, calculating according to a preset engine energy conservation formula to obtain the heat absorbed by the engine cooling liquid;
the cooling liquid is used for dissipating heat of the vehicle engine and protecting the engine from normal operation.
In general, the engine energy conservation formula is Pf＝Pe+PCooling liquid+PExhaust of gases+PInter-cooler+PHeat generation，PfEmitted for combustion of engine fuelTotal power, PeFor the total power output of the engine, PExhaust of gasesPower lost to engine exhaust, PInter-coolerPower lost to cold in the engine intake, PCooling liquidPower lost to engine coolant, PHeat generationIs a residual power loss of the engine.
In a possible implementation manner, after the actual water temperature at the current moment is determined, the total power generated by fuel combustion of the engine is calculated firstly, the output power of the engine, the heat lost by exhaust, the heat lost in intake air and the residual heat loss of the engine are calculated respectively, then the output power of the engine, the heat lost by exhaust, the heat lost in intake air and the residual heat loss of the engine are added to obtain the total power used by the engine, and finally the total power and the total power used are differentiated through a preset engine energy conservation formula to generate the heat absorbed by the engine coolant.
In particular, PfThe total power generated for the combustion of the engine fuel is: pf＝QFuel*HuWherein Q isFuelThe accumulated mass flow of the fuel oil of the engine can be obtained by calculating the energizing pulse width of a fuel nozzle, correcting the fuel temperature and correcting the fuel pressure; huThe fuel has low heat value, and corresponding value can be found according to the type of the fuel.
PeThe calculation formula is that the engine outputs total power: peN Torque/9550, where N is the engine speed, which can be found by actual measurement; torque is engine output Torque and can be obtained through model calculation, and deviation between the general model calculation Torque and the actual output Torque of the rack is controlled within 3%.
PExhaust of gasesThe power lost to engine exhaust is: pExhaust of gases＝QExhaust of gases*(tout-tEnvironment(s))*Cp exhaustBecause of the difficulty in exhaust flow measurement, exhaust flow is typically expressed as the sum of fuel flow and intake air flow, QExhaust of gases＝QFuel+QIntake air；toutFor supercharger outlet exhaust temperature, which may be dependent on supercharger inletMouth temperature tinIs calculated as tinSubtracting the pressure drop obtained by looking up the table for the rotational speed load and passing through the ambient temperature tEnvironment(s)The correction is carried out, and the value is calibrated to be determined and controlled within +/-30 ℃ of the actual supercharger exhaust outlet temperature precision; t is tEnvironment(s)The system is provided with a sensor, and the ambient temperature around the engine is measured; cp exhaustThe specific constant pressure heat capacity of the exhaust gas can be calculated from the fuel combustion components.
PInter-coolerThe power of the air cooling loss in the air inlet of the engine is as follows: pInter-cooler＝QIntake air*(tBefore intercooling*Cp before intercooling-tAfter intercooling*CAfter p is intercooled) Wherein the flow rate of intake air QIntake airThe air intake flow sensor can be used for directly measuring the air intake flow, if the air intake flow sensor is not available, the air intake flow sensor can be used for calculating the air intake flow, the air intake flow can be obtained by looking up a table by utilizing the opening of the air throttle and the rear pressure ratio of the air throttle, and the accuracy of the corrected air intake flow and the actual air intake flow needs to be controlled within 3 percent; the pre-intercooling temperature is the outlet temperature of the pressure end of the supercharger and can be obtained through calculation, the pre-intercooling temperature is the air heated by the supercharger and then reaches the intercooler, therefore, the heating effect of the supercharger on the air needs to be considered, the exhaust temperature of the inlet of the supercharger of the engine is obtained through actual measurement, the air temperature of the inlet of the supercharger is the ambient temperature, and the ambient temperature is corrected according to the air inlet flow, the efficiency of the supercharger of the engine and the temperature of the inlet of the exhaust of the supercharger, so that the. t is tAfter intercoolingThe temperature is the outlet temperature of the intercooler and is directly measured by a sensor; inlet air ratio constant pressure heat capacity Cp before intercooling＝Cp standard+tBefore intercooling*facCorrectionWherein the correction factor facCorrectionIs obtained according to the intercooling front inlet air temperature; inlet air ratio constant pressure heat capacity CAfter p is intercooled＝Cp standard+tAfter intercooling*facCorrectionWherein the correction factor facCorrectionIs obtained according to the intake air temperature after intercooling.
PHeat generationThe residual power loss of the engine mainly comprises heat radiation loss and other losses, generally about 5 percent of the total heat of engine fuel, and the calibration can be carried out according to 5 percentAnd (5) line calculation.
Further, by QFuel*HuMinus Pe+PExhaust of gases+PInter-cooler+PHeat generationFinally obtaining the heat absorbed by the engine cooling liquid.
S103, calculating to obtain the water temperature of an engine model based on the heat absorbed by the engine cooling liquid;
by determining the current absorbed heat of the vehicle engine coolant, the engine model water temperature can be determined by the absorbed heat of the engine coolant and other parameters.
In a possible implementation manner, after the heat absorbed by the engine coolant is determined, the coolant flow, the starting water temperature and the specific heat capacity corresponding to the coolant of the engine are firstly obtained, and finally the engine model water temperature is generated by calculating according to the heat absorbed by the engine coolant, the coolant flow, the starting water temperature and the specific heat capacity corresponding to the coolant.
In particular, PCooling liquidThe power lost for the engine coolant is: pCooling liquid＝QCooling liquid*(tModel (model)-tStarting up)*Cp cooling liquidWherein Q isCooling liquidThe flow of the cooling liquid of the engine is obtained by calibrating because the thermostat is not opened and the engine runs in a small cycle; t is tModel (model)The temperature that we need to obtain; t is tStarting upWater temperature when the engine is started; cp cooling liquidThe specific constant pressure heat capacity of the engine coolant. The heat taken away by the engine coolant mainly comprises heat which is transferred to cooling water after mechanical loss is converted into heat, heat loss which is transferred to a cylinder wall by in-cylinder combustion, heat loss which is transferred to the coolant by exhaust gas channels and the like.
Thus, P is obtainedCooling liquidFor power lost by engine coolant, by obtaining QCooling liquid、tModel (model)、tStarting up、Cp cooling liquidCorresponding parameters are substituted into formula PCooling liquid＝QCooling liquid*(tModel (model)-tStarting up)*Cp cooling liquidFinally, t is obtained by calculationDie(i.e., engine model water temperature).
S104, making a difference between the water temperature of the engine model and the actual water temperature of the engine to generate a temperature difference;
in one possible implementation manner, after the engine actual water temperature is obtained based on step S101 and the engine model water temperature is obtained based on step S103, the temperature difference t is obtained by subtracting the calculated model water temperature from the actual water temperaturediff。
And S105, determining whether the engine thermostat has a clamping stagnation fault or not based on the temperature difference.
In one possible implementation, the engine temperature rises faster when the thermostat is normal, so t is the time when the thermostat is not malfunctioningdiffThe difference is small; when the thermostat is stuck open or not tightly sealed, the actual water temperature rises slowly, so the temperature difference tdiffIt will be larger, and when it is larger than a pre-calibrated value, it will report out the jamming failure of the thermostat.
For example, as shown in fig. 2, first, a starter is powered on at T15, and when the starter is started to drive the engine to reach a certain rotation speed, the engine is started and the starter is exited. After the engine is started, calculating the accumulated combustion heat P of the enginefRespectively calculating the output power P of the engineeHeat lost from exhaust gas PExhaust of gasesHeat of cold loss in intake air PInter-coolerAnd residual heat loss P of engineHeat generationThen P is addedf、Pe、PExhaust of gases、PInter-cooler、PHeat generationSubstituting into formula PCooling down＝Pf-Pe-PExhaust of gases-PInter-cooler-PHeat generationFinally obtaining the power P of the cooling liquidCooling downThen according to the cooling liquid power PCooling downAnd obtaining an engine model water temperature t model by using the known parameters, subtracting the actual water temperature from the model water temperature t model to generate a temperature difference, and finally judging whether the water temperature difference is smaller than a set judgment value.
And if the judgment result is yes, the thermostat is normal, and if the judgment result is no, the thermostat is stuck and reports a fault.
In the embodiment of the application, the device for detecting the clamping stagnation fault of the engine thermostat firstly obtains the actual water temperature of the engine, then calculates the absorbed heat of the engine cooling liquid according to a preset engine energy conservation formula to obtain the water temperature of an engine model based on the absorbed heat of the engine cooling liquid, then differentiates the water temperature of the engine model with the actual water temperature of the engine to generate a temperature difference, and finally determines whether the clamping stagnation fault occurs in the engine thermostat based on the temperature difference. According to the method and the device, the theoretical model water temperature of the engine can be calculated by utilizing energy conservation according to the engine heat balance theory, the model water temperature is compared with the actual water temperature in a difference mode, and the temperature difference is larger than a certain value within a certain time after the engine is started, so that the blocking of the thermostat is judged, the false alarm of the blocking fault of the thermostat of the engine is reduced, and the running stability of the system is improved.
Please refer to fig. 3, which is a flowchart illustrating a method for detecting a sticking fault of an engine thermostat according to an embodiment of the present disclosure. The present embodiment is exemplified by applying the method for detecting the stuck fault of the thermostat of the engine to the electronic device. The method for detecting the clamping stagnation fault of the engine thermostat can comprise the following steps of:
s201, detecting the actual water temperature of the current engine in real time through a temperature sensor;
s202, calculating total power generated by fuel combustion of the engine;
in a possible implementation mode, firstly, the energizing pulse width, the fuel temperature correction and the fuel pressure correction of a fuel nozzle of an engine are obtained, then the accumulated mass flow of fuel oil of the engine is obtained through the energizing pulse width, the fuel temperature correction and the fuel pressure correction calculation, then the fuel type corresponding to the fuel of the engine is obtained, and finally the total power generated by the fuel combustion of the engine is obtained through calculation according to the accumulated mass flow of the fuel oil of the engine and the fuel type.
S203, calculating the total power of the engine, wherein the total power of the engine is the sum of the output power of the engine, the heat lost by exhaust, the heat lost in intake air and the residual heat loss of the engine;
in one possible implementation, the amount of heat lost by engine exhaust is calculated by first adding the current vehicle fuel flow and intake air flow to generate an exhaust flow, measuring the engine ambient temperature and the current vehicle supercharger outlet exhaust temperature, calculating the specific constant pressure heat capacity of the exhaust from the engine fuel combustion components, and finally calculating the power lost by engine exhaust based on the exhaust flow, the engine ambient temperature, the supercharger outlet exhaust temperature, and the specific constant pressure heat capacity of the exhaust.
The method for calculating the heat loss of the engine in air intake comprises the steps of firstly measuring the air intake flow of the engine, then correcting and calculating according to the air intake flow, the efficiency of a supercharger of the engine and the temperature of an exhaust inlet of the supercharger to generate the temperature of air before an intercooler, then measuring the temperature of an outlet of the intercooler by adopting a sensor, then generating the constant pressure heat capacity of the air before intercooling and the constant pressure heat capacity of the air after intercooling according to the temperature of the air before the intercooler and the temperature of the outlet of the intercooler, and finally calculating according to the air intake flow, the temperature of the air before the intercooler, the temperature of the outlet of the intercooler, the constant pressure heat capacity of the air before the intercooling and the constant pressure.
The engine residual power loss is calculated by multiplying a preset percentage by the total power generated by the combustion of fuel in the engine to generate the engine residual power loss.
S204, subtracting the total power from the total power by a preset engine energy conservation formula to generate engine cooling liquid absorption heat;
s205, obtaining the flow rate of cooling liquid of the engine, the water temperature when the engine is started and the corresponding specific heat capacity of the cooling liquid;
s206, calculating according to the heat absorbed by the engine cooling liquid, the flow rate of the cooling liquid, the water temperature during starting and the corresponding specific heat capacity of the cooling liquid to generate the water temperature of an engine model;
s207, making a difference between the water temperature of the engine model and the actual water temperature of the engine to generate a temperature difference;
s208, judging whether the temperature difference is larger than a preset threshold value or not;
and when the judgment result is that the temperature difference is larger than the preset threshold value, the step S209 is entered, otherwise, the step S210 is entered.
S209, the engine thermostat has a clamping stagnation fault;
s210, the engine thermostat has no clamping stagnation fault;
the invention utilizes the law of conservation of energy, the heat generated by the combustion of the engine fuel is the total input heat, the fuel mass flow is the existing algorithm parameter when the ECU runs, the error between the fuel mass flow and the actual fuel mass flow can be controlled within 2% according to experience, the output energy is the exhaust heat, the intercooler heat, the coolant heat, the engine output power and other residual heat losses, and each part of the output energy can obtain more accurate figures through software calculation, so the temperature reliability of the engine water temperature model is higher, and the derivation mode is not limited by the change of the environmental temperature and the load change of the engine, thereby greatly improving the robustness of fault diagnosis.
In the embodiments disclosed herein, it should be understood that the disclosed methods, articles of manufacture (including but not limited to devices, apparatuses, etc.) may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, a division of a unit is merely a logical division, and an actual implementation may have another division, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form. Units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment. In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.
It should be understood that the flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions. The present invention is not limited to the procedures and structures that have been described above and shown in the drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.
Claims (10)
1. A method for detecting an engine thermostat sticking fault is characterized by comprising the following steps:
acquiring the actual water temperature of an engine;
calculating according to a preset engine energy conservation formula to obtain the heat absorbed by the engine cooling liquid;
calculating to obtain the water temperature of an engine model based on the heat absorbed by the engine cooling liquid;
making a difference between the engine model water temperature and the actual engine water temperature to generate a temperature difference;
determining whether a stuck fault has occurred with the engine thermostat based on the temperature difference.
2. The method of claim 1, wherein prior to obtaining the actual water temperature of the engine, further comprising:
and detecting the actual water temperature of the current engine in real time through a temperature sensor.
3. The method according to claim 1 or 2, wherein the calculating of the engine coolant absorbed heat according to a preset engine energy conservation formula comprises:
calculating a total power emitted by fuel combustion of the engine;
calculating the total power utilization of the engine, wherein the total power utilization is the sum of the output power of the engine, the heat lost by exhaust, the heat lost in intake air and the residual heat loss of the engine;
and subtracting the total power from the total power utilization through a preset engine energy conservation formula to generate heat absorbed by engine cooling liquid.
4. The method of claim 3, wherein said calculating the total power emitted by fuel combustion of said engine comprises:
acquiring the energizing pulse width of a fuel nozzle of the engine, correcting the fuel temperature and correcting the fuel pressure;
calculating to obtain the accumulated mass flow of the fuel oil of the engine through the energizing pulse width of the fuel nozzle, the correction of the fuel temperature and the correction of the fuel pressure;
acquiring a fuel model corresponding to the fuel of the engine;
and calculating the total power generated by the combustion of the fuel of the engine according to the accumulated mass flow of the fuel of the engine and the fuel type.
5. The method according to claim 1 or 2, wherein the calculating an engine model water temperature based on the engine coolant absorbed heat includes:
obtaining the flow rate of cooling liquid of the engine, the water temperature when the engine is started and the corresponding specific heat capacity of the cooling liquid;
and calculating according to the heat absorbed by the engine cooling liquid, the flow rate of the cooling liquid, the water temperature at the starting time and the specific heat capacity corresponding to the cooling liquid to generate the water temperature of the engine model.
6. The method of claim 1, wherein said determining whether the engine thermostat has a stuck fault based on the temperature difference comprises:
when the temperature difference is larger than or equal to a preset threshold value, the engine thermostat has a clamping stagnation fault;
and when the temperature difference is smaller than a preset threshold value, the engine thermostat has no clamping stagnation fault.
7. The method of claim 3, wherein the preset engine energy conservation formula is:
Pf＝Pe+Pcooling liquid+PExhaust of gases+PInter-cooler+PHeat generation
Wherein, PfTotal power, P, generated for combustion of engine fueleFor the total power output of the engine, PExhaust of gasesPower lost to engine exhaust, PInter-coolerPower lost to cold in the engine intake, PCooling liquidPower lost to engine coolant, PHeat generationIs a residual power loss of the engine.
8. The method of claim 7, wherein the power lost by the engine exhaust comprises:
adding the fuel flow and the intake air flow of the current vehicle to generate exhaust flow;
measuring the ambient temperature of the engine and the current exhaust temperature at the outlet of the vehicle supercharger;
calculating specific constant pressure heat capacity of exhaust gas according to the engine fuel combustion component;
and calculating based on the exhaust flow, the ambient temperature of the engine, the exhaust temperature at the outlet of the supercharger and the specific constant pressure heat capacity of the exhaust to generate the power lost by the exhaust of the engine.
9. The method of claim 7, wherein the power lost to cooling in the engine intake comprises:
measuring an intake air flow rate of the engine;
calculating according to the intake air flow, the efficiency of the engine supercharger and the temperature correction of the exhaust inlet of the supercharger to generate the temperature of air before an intercooler;
measuring the outlet temperature of the intercooler by using a sensor;
generating intercooling front air inlet ratio constant pressure heat capacity and intercooling rear air inlet ratio constant pressure heat capacity according to the intercooler front air temperature and the intercooler outlet temperature;
and calculating based on the air intake flow, the air temperature before the intercooler, the outlet temperature of the intercooler, the air intake ratio constant pressure heat capacity before the intercooler and the air intake ratio constant pressure heat capacity after the intercooler to generate the power of the air intake intercooling loss of the engine.
10. The method of claim 7, wherein the engine residual power loss comprises:
the engine residual power loss is generated by multiplying a preset percentage by the total power generated by the combustion of fuel by the engine.
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