JP4497268B2 - Fuel temperature estimation device and abnormality diagnosis device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel temperature estimation device that estimates a fuel temperature in a fuel tank and an abnormality diagnosis device that uses the estimated fuel temperature as abnormality diagnosis data.
[0002]
[Prior art]
The fuel temperature in a fuel tank mounted on an automobile changes due to various factors. For example, since the fuel tank is mounted at the rear of an automobile, the exhaust heat of the internal combustion engine (engine) is transmitted to the fuel tank, the fuel temperature in the fuel tank rises, and fuel is injected from the fuel tank with the fuel pump. In the fuel return system in which the surplus fuel sent to the valve is returned into the fuel tank, the fuel temperature also rises due to the fuel (return fuel) returned from the fuel injection valve side into the fuel tank. Further, the fuel temperature is lowered by the air cooling effect (heat radiation effect) of the fuel tank by the traveling wind, and the behavior of the change of the fuel temperature varies depending on the outside air temperature.
[0003]
As the fuel temperature in the fuel tank increases, the amount of evaporation gas (fuel evaporative gas) generated in the fuel tank increases and the internal pressure of the fuel tank increases. The evaporative gas generated in the fuel tank is adsorbed by the canister, and the evaporative gas is released (purged) from the canister to the engine intake system according to the operating state. In order to detect the "evaporation system", the inside of the evaporation system including the fuel tank is sealed, the internal pressure of the fuel tank is detected by a pressure sensor, and the presence or absence of the leakage of the evaporation system is determined based on the amount of change in the internal pressure of the fuel tank within a predetermined period I try to diagnose.
[0004]
In this case, since the internal pressure of the fuel tank changes according to the fuel temperature in the fuel tank, as shown in JP-A-6-81727, a fuel temperature sensor for detecting the fuel temperature in the fuel tank is installed. When the temperature difference between the fuel temperature when the engine is stopped and the fuel temperature when the engine is started is greater than or equal to a predetermined value, the evaporation depends on whether or not the differential pressure between the fuel tank internal pressure and the atmospheric pressure is greater than or equal to the predetermined value. It has been proposed to perform system leak diagnosis.
[0005]
[Problems to be solved by the invention]
However, in the above-described configuration, it is necessary to newly provide a fuel temperature sensor in order to detect the fuel temperature in the fuel tank, and there is a disadvantage that the manufacturing cost increases accordingly.
In addition, when a fuel temperature sensor is provided, there is a problem of how to perform abnormality diagnosis of the fuel temperature sensor in order to ensure system reliability.
[0006]
The present invention has been made in consideration of these circumstances, and a first object is to provide a fuel temperature estimation device capable of detecting the fuel temperature in the fuel tank without providing a fuel temperature sensor. In addition, a second object is to provide an abnormality diagnosis device that can perform abnormality diagnosis of the evaporation gas purge system in consideration of the fuel temperature in the fuel tank without providing a fuel temperature sensor. In addition, a third object is to provide an abnormality diagnosis device capable of performing abnormality diagnosis of a fuel temperature sensor in a system provided with a fuel temperature sensor.
[0007]
[Means for Solving the Problems]
  In order to achieve the first object, a fuel temperature estimation device according to claim 1 of the present invention is a fuel temperature estimation apparatus in which the exhaust heat is transferred into the fuel tank based on the operation state during operation of the internal combustion engine. Fuel temperature rise estimation means for estimating the rise in fuel temperature, and the air temperature inside the fuel tank due to the air cooling effect (heat radiation effect) based on the vehicle speed and / or intake air temperature or information correlated therewith (for example, outside temperature) A fuel temperature decrease estimation means for estimating a fuel temperature decrease; a current fuel temperature based on the fuel temperature increase estimation means and the fuel temperature increase and decrease estimates estimated by the fuel temperature decrease estimation means; A fuel temperature estimating means for updating the estimated value ofThe fuel temperature estimating means correlates with the estimated fuel temperature value when the internal combustion engine was stopped last time, the elapsed time from the previous internal combustion engine operation stop to the current internal combustion engine start, and the outside air temperature or this. Based on the information, the initial value of the fuel temperature at the start of the internal combustion engine is estimated.With this configuration, the fuel temperature in the fuel tank can be determined during operation of the internal combustion engine without providing a fuel temperature sensor.
[0008]
  Generally, since the fuel tank is mounted on the rear part of the automobile, the exhaust heat of the internal combustion engine is transmitted to the fuel tank, and the fuel temperature in the fuel tank rises. Considering this point, when estimating the fuel temperature increase amount as in claim 1, if the fuel temperature increase amount due to the exhaust heat being transferred into the fuel tank is estimated, the operation of the internal combustion engine is performed. It is possible to estimate the increase in fuel temperature due to exhaust heat, which is the main cause of the increase in fuel temperature.
  Moreover, as in claim 1, the estimated fuel temperature when the internal combustion engine was stopped last time, the elapsed time from the previous stop of the internal combustion engine to the start of the current internal combustion engine, and the outside air temperature or a correlation therewith If the initial value of the fuel temperature at the start of the internal combustion engine is estimated based on certain information (such as the intake air temperature), the amount of decrease in the fuel temperature due to heat dissipation during the operation stop of the internal combustion engine can be calculated using the previous internal combustion engine. Estimated based on the elapsed time from the shutdown to the current start of the internal combustion engine and the outside air temperature or information correlated therewith (intake air temperature, etc.), and from the estimated fuel temperature estimated at the previous stop of the internal combustion engine By subtracting the amount of decrease in fuel temperature due to heat dissipation while the internal combustion engine is stopped, it is possible to estimate the initial value of the fuel temperature when the internal combustion engine is started this time. When the initial value of the fuel temperature estimated in this way is lower than the outside air temperature (or intake air temperature), the initial value of the fuel temperature may be set to the same temperature as the outside air temperature (or intake air temperature).
[0009]
  For example, in a system having an exhaust temperature sensor for detecting an exhaust temperature, an increase in fuel temperature due to exhaust heat may be estimated based on the output of the exhaust temperature sensor. Term2As described above, the increase in the fuel temperature in the fuel tank may be estimated based on the rotational speed and / or load (for example, intake pipe pressure, intake air amount, throttle opening, etc.) of the internal combustion engine. In general, the exhaust heat increases as the rotational speed of the internal combustion engine increases, and the exhaust heat increases as the load increases. Therefore, the increase in the fuel temperature due to the exhaust heat is estimated based on the rotational speed and load of the internal combustion engine. be able to.
[0010]
  Further, in a fuel return system in which surplus fuel sent from the fuel tank to the fuel injection valve by the fuel pump is returned to the fuel tank, fuel (return fuel) is returned from the fuel injection valve side to the fuel tank. However, the fuel temperature will rise. Therefore, in this fuel return system, the claims3As described above, in addition to the increase in the fuel temperature in the fuel tank due to the exhaust heat, the increase in the fuel temperature due to the fuel (return fuel) returned from the fuel injection valve side to the fuel tank may be estimated. In this way, it is possible to accurately estimate the increase in the fuel temperature in consideration of both the exhaust heat and the return fuel, which are the two major causes of the fuel temperature increase in the fuel return system. In a fuel returnless system that does not return fuel from the fuel injector side to the fuel tank, it is not necessary to consider the increase in fuel temperature due to the return fuel, but only the effect of exhaust heat is considered. Can be estimated.
[0011]
  Claims4As described above, in the fuel system in which the fuel pump is arranged in the fuel tank, the increase in the fuel temperature due to the heat generated by the fuel pump may be estimated. At this time, the amount of heat generated by the fuel pump may be estimated from the power supplied to the fuel pump.
[0012]
By the way, even if the amount of heat exchanged by the fuel in the fuel tank is the same, the amount of change in the fuel temperature varies depending on the remaining amount of fuel in the fuel tank. For example, as the remaining amount of fuel in the fuel tank decreases, the increase in fuel temperature due to exhaust heat or the like tends to increase. In addition, when the fuel temperature in the fuel tank is high, the temperature difference between the traveling wind temperature (outside air temperature) and the fuel temperature increases, and the amount of decrease in the fuel temperature due to the air cooling effect (heat radiation effect) tends to increase. On the contrary, when the fuel temperature in the fuel tank is low, the increase in the fuel temperature due to exhaust heat or the like tends to be relatively large.
[0013]
  Considering these characteristics, the claims5As described above, the current fuel temperature estimated value may be corrected by the correcting means based on the remaining amount of fuel in the fuel tank and / or the previous fuel temperature estimated value. Thereby, the estimation accuracy of the fuel temperature can be further improved.
[0014]
  Further, as in claim 6, the estimated fuel temperature when the internal combustion engine was stopped last time and the current internal combustion engine operation stopStart fuel temperature estimation calculationBased on the elapsed time and the outside air temperature or information (intake air temperature, etc.)At start of fuel temperature estimation calculationFuel temperatureDegreeIt may be estimated. In other words, the internal combustion engine is stoppedUntil the start of the fuel temperature estimation calculationThe amount of decrease in fuel temperature due to heat dissipation is calculated from the previous stoppage of the internal combustion engine.Start fuel temperature estimation calculationEstimated based on the elapsed time until and the outside air temperature or information correlated therewith (intake air temperature, etc.), and from the estimated fuel temperature estimated when the internal combustion engine was stopped last time. By subtracting the fuel temperature drop,At start of fuel temperature estimation calculationFuel temperatureDegreeCan be estimated. Fuel temperature estimated in this wayDegreeIf it is lower than the outside air temperature (or intake air temperature),DegreeWhat is necessary is just to set to the same temperature as external temperature (or intake temperature).
[0020]
  In order to achieve the second object, a claim is provided.7As described above, in the abnormality diagnosis apparatus provided with abnormality diagnosis means for performing abnormality diagnosis of the evaporation gas purge system during operation of the internal combustion engine, the above-described claims 1 to6The estimated fuel temperature value during the operation of the internal combustion engine by any one of the methods may be used as an abnormality diagnosis execution condition determination parameter and / or an abnormality diagnosis parameter. In this way, it is possible to perform abnormality diagnosis of the evaporation gas purge system in consideration of the fuel temperature in the fuel tank during operation of the internal combustion engine without providing a fuel temperature sensor.
[0021]
  At this time, the claim8As described above, one of the abnormality diagnosis execution conditions may be that the estimated fuel temperature value estimated by the fuel temperature estimation device is equal to or lower than a predetermined temperature. This is because when the fuel temperature is high, the amount of evaporative gas generated in the fuel tank increases, and the difference between the change in the internal pressure of the fuel tank at the time of a small leak and the change in the internal pressure of the fuel tank at the normal time decreases. It is because it becomes difficult to do. Therefore, if the abnormality diagnosis of the evaporation gas purge system is prohibited when the estimated fuel temperature is higher than the predetermined temperature, the erroneous diagnosis due to the excessive generation of the evaporation gas can be prevented and the reliability of the abnormality diagnosis can be improved.
[0028]
  In order to achieve the third object, a claim is provided.9As described above, in the system including the fuel temperature sensor for detecting the fuel temperature in the fuel tank, the claims 1 to6An abnormality diagnosis of the fuel temperature sensor may be performed based on the relationship between the estimated fuel temperature value and the detected value of the fuel temperature sensor. For example, if the error between the estimated fuel temperature value and the detected value of the fuel temperature sensor exceeds the normal error range, it can be diagnosed that the fuel temperature sensor is abnormal.
[0029]
  Or claims10As described above, the abnormality diagnosis of the fuel temperature sensor may be performed based on the relationship between the change amount of the estimated fuel temperature value within the predetermined period and the change amount of the detection value of the fuel temperature sensor. In other words, the estimated fuel temperature value differs depending on how the initial value is determined, but the change behavior is a change behavior with the same tendency even if the initial value is slightly different. Therefore, if an abnormality diagnosis of the fuel temperature sensor is performed based on the relationship between the change amount of the estimated fuel temperature value and the change amount of the detected value of the fuel temperature sensor within a predetermined period, the initial value of the estimated fuel temperature value is slightly different. Even if there is, the presence or absence of abnormality of the fuel temperature sensor can be accurately diagnosed without being affected by it.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
[Embodiment (1)]
Hereinafter, an embodiment (1) in which the present invention is applied to an abnormality diagnosis apparatus for an evaporation gas purge system will be described with reference to FIGS.
[0031]
First, the configuration of the evaporation gas purge system will be described with reference to FIG. A canister 13 is connected to the fuel tank 11 via an evaporation passage 12. The canister 13 accommodates an adsorbent (not shown) such as activated carbon that adsorbs evaporation gas (evaporated fuel gas). An atmospheric on / off valve 14 is attached to the atmospheric communication hole in the bottom surface of the canister 13.
[0032]
This atmospheric on-off valve 14 is constituted by a normally-open electromagnetic valve, and is kept open when the power is off, and the atmospheric communication hole of the canister 13 is kept open to the atmosphere. It is. When the air on / off valve 14 is energized, it closes and the air communication hole of the canister 13 is closed.
[0033]
On the other hand, a purge passage 15 is provided between the canister 13 and the engine intake system to purge (release) the evaporated gas adsorbed by the adsorbent in the canister 22 into the engine intake system. A purge control valve 16 for controlling the purge flow rate is provided on the way. The purge control valve 16 is constituted by a normally closed electromagnetic valve, and controls the purge flow rate of the evaporation gas from the canister 13 to the engine intake system by duty control of energization.
[0034]
The fuel tank 11 is provided with a tank internal pressure sensor 17 for detecting the internal pressure. When the evaporation system from the fuel tank 11 to the purge control valve 16 is sealed, the internal pressure of the fuel tank 11 and the internal pressure of other parts of the evaporation system coincide with each other. By detecting, the pressure in the evaporation system can be detected.
[0035]
A fuel level sensor 18 for detecting the remaining amount of fuel is provided in the fuel tank 11. In addition, various sensors such as a water temperature sensor 19 for detecting the engine cooling water temperature and an intake air temperature sensor 20 for detecting the intake air temperature are provided.
[0036]
Outputs of these various sensors are input to the control circuit 21. A power supply voltage is supplied to the power supply terminal of the control circuit 21 via the main relay 22. In addition, the power supply voltage is also supplied to the atmospheric opening / closing valve 14, the purge control valve 16, the tank internal pressure sensor 17 and the fuel level sensor 18 via the main relay 22. The relay drive coil 22b that drives the relay contact 22a of the main relay 22 is connected to the main relay control terminal of the control circuit 21. When the relay drive coil 22b is energized, the relay contact 22a is turned on and the control circuit 21 is turned on. The power supply voltage is supplied to the air opening / closing valve 14, the purge control valve 16, the tank internal pressure sensor 17, and the fuel level sensor 18. Then, by turning off the energization to the relay drive coil 22b, the relay contact 22a is turned off, and the power supply to the control circuit 21 and the like is turned off. An on / off signal of the ignition switch 23 is input to the key SW terminal of the control circuit 21. Further, the control circuit 21 includes a backup power source 24 and a soak timer 25 that operates with the backup power source 24 as a power source. The soak timer 25 starts a time measuring operation after the engine is stopped (after the ignition switch 23 is turned off), and measures an elapsed time after the engine is stopped.
[0037]
The control circuit 21 is mainly composed of a microcomputer, and executes a fuel injection control program, an ignition control program, and a purge control program stored in a ROM (storage medium) to thereby perform fuel injection control, ignition control, and purge control. I do. Further, the control circuit 21 executes the routines shown in FIGS. 2 to 6 stored in the ROM to estimate the fuel temperature in the fuel tank 11 while the engine is running and the engine is stopped. Evapo system leak diagnosis is executed using the estimated value.
Here, the fuel temperature estimation method of the present embodiment (1) will be described.
[0038]
《Fuel temperature estimation method during engine operation》
During engine operation, the fuel temperature Ton (i) in the fuel tank 11 is estimated by the following equation.
Ton (i) = (Tonup−Tondown) × Fon + Ton (i−1)
Tonup: Fuel temperature rise in the fuel tank 11 per calculation cycle
Tondown: Fuel temperature drop in the fuel tank 11 per calculation cycle
Fon: Correction coefficient
Ton (i-1): Previous fuel temperature estimate
[0039]
Here, the fuel temperature increase Tonup is the fuel temperature increase due to the exhaust heat that is the main factor of the fuel temperature increase during engine operation being transmitted into the fuel tank 11. In a system equipped with an exhaust temperature sensor that detects the exhaust temperature, the increase in fuel temperature due to exhaust heat may be estimated based on the output of the exhaust temperature sensor. However, in a system that does not have an exhaust temperature sensor, the engine speed Further, the fuel temperature increase may be calculated by a map or a mathematical expression based on the load (for example, intake pipe pressure, intake air amount, throttle opening, etc.). Generally, the exhaust heat increases as the engine speed increases, and the exhaust heat increases as the load increases. Therefore, the increase in the fuel temperature due to the exhaust heat can be estimated based on the engine speed and the load.
[0040]
In the fuel return system in which the surplus fuel sent from the fuel tank 11 to the fuel injection valve (not shown) by the fuel pump (not shown) is returned to the fuel tank 11, the fuel injection valve side The fuel temperature also rises due to the fuel returned to the fuel tank 11 (return fuel). Therefore, in the fuel return system, the fuel temperature increase due to the return fuel is considered in addition to the fuel temperature increase due to the exhaust heat.
Fuel temperature rise Tonup of fuel return system
= Fuel temperature rise due to exhaust heat + Fuel temperature rise due to return fuel
[0041]
In this way, it is possible to accurately estimate the fuel temperature increase Tonup in consideration of both exhaust heat and return fuel, which are the two major causes of the fuel temperature increase in the fuel return system.
[0042]
In the fuel returnless system that does not return the fuel from the fuel injection valve side to the fuel tank 11, it is not necessary to consider the increase in the fuel temperature due to the return fuel, and the increase in the fuel temperature only considering the influence of the exhaust heat. Just estimate the minutes.
Fuel returnless system
Fuel temperature rise Tonup = Fuel temperature rise due to exhaust heat
[0043]
Further, in the fuel system in which the fuel pump is arranged in the fuel tank 11, the increase in the fuel temperature due to the heat generated by the fuel pump 11 may be estimated. At this time, the calorific value of the fuel pump may be estimated by a map or a mathematical formula depending on the electric power supplied to the fuel pump.
[0044]
On the other hand, the fuel temperature drop Tondown is the fuel temperature drop in the fuel tank 11 due to the air cooling effect (heat radiation effect) caused by the temperature difference between the traveling wind or outside air temperature and the fuel temperature (temperature of the fuel tank 11). This fuel temperature drop Tondown is calculated by a map or a mathematical expression using vehicle speed and / or intake air temperature as parameters. The outside air temperature may be used instead of the intake air temperature, or the temperature difference between the intake air temperature (or outside air temperature) and the previous estimated fuel temperature value Ton (i-1) may be used.
[0045]
The correction coefficient Fon is a correction coefficient for correcting the current fuel temperature estimated value Ton (i) based on the remaining amount of fuel in the fuel tank 11 and / or the previous fuel temperature estimated value Ton (i-1). It is.
[0046]
In general, even if the amount of heat transferred by the fuel in the fuel tank 11 is the same, the amount of change in the fuel temperature varies depending on the remaining amount of fuel in the fuel tank 11. For example, as the remaining amount of fuel in the fuel tank 11 decreases, the fuel temperature increase Tonup due to exhaust heat or the like tends to increase. Further, when the fuel temperature in the fuel tank 11 is high, the temperature difference between the temperature of the traveling wind (outside air temperature) and the fuel temperature increases, and the fuel temperature decrease Tondown due to the air cooling effect (heat radiation effect) tends to increase. On the contrary, when the fuel temperature in the fuel tank 11 is low, the fuel temperature increase Tonup due to exhaust heat or the like tends to be relatively large.
[0047]
In consideration of such characteristics, in the present embodiment (1), the correction coefficient Fon is used to determine the remaining amount of fuel in the fuel tank 11 and / or the previous estimated fuel temperature value Ton (i-1). This time, the estimated fuel temperature value Ton (i) is corrected. When the correction coefficient Fon is set based on the fuel remaining amount in the fuel tank 11, the correction coefficient Fon is set to the reference value “1” when the fuel remaining amount is 50%, and the correction coefficient Fon decreases as the fuel remaining amount decreases. The correction coefficient Fon is increased as the remaining amount of fuel increases. When the correction coefficient Fon is set based on the previous estimated fuel temperature value Ton (i-1), the correction coefficient Fon is increased as the previous estimated fuel temperature value Ton (i-1) decreases.
[0048]
On the other hand, the initial value of the fuel temperature estimated value Ton (i) during engine operation (fuel temperature at the beginning of engine start) is the last estimated fuel temperature just before the previous engine stop and the current estimated value from the previous engine stop. This is estimated based on the elapsed time until the engine is started and the outside air temperature (or intake air temperature). That is, the amount of decrease in fuel temperature due to heat dissipation while the engine is stopped is estimated based on the elapsed time from the previous engine stop to the current engine start and the outside air temperature (or intake air temperature). The initial value of the fuel temperature at the time of starting the engine this time is estimated by subtracting the amount of decrease in the fuel temperature due to heat dissipation during the engine stop from the estimated fuel temperature value. When the initial value of the fuel temperature estimated in this way is lower than the outside air temperature (or intake air temperature), the initial value of the fuel temperature may be set to the same temperature as the outside air temperature (or intake air temperature).
[0049]
In the present embodiment (1), even when the engine is stopped, the fuel temperature is estimated by a method described later until the evaporative leak diagnosis is completed. Therefore, the estimated fuel temperature value Ton (i) during engine operation is The initial values are the estimated fuel temperature estimated last while the engine was stopped, the elapsed time from the end of this fuel temperature estimation (end of leak diagnosis) to the current engine start, and the outside air temperature (or intake air temperature). You may make it estimate based on it. In this case as well, when the estimated initial value of the fuel temperature is lower than the outside air temperature (or intake air temperature), the initial value of the fuel temperature may be set to the same temperature as the outside air temperature (or intake air temperature).
[0050]
<Method for estimating fuel temperature while engine is stopped>
For estimating the fuel temperature in the fuel tank 11 when the engine is stopped, the estimated fuel temperature value Ton (i) last estimated immediately before the engine is stopped is used as an initial value.
[0051]
While the engine is stopped, the fuel temperature Toff (i) in the fuel tank 11 is estimated by the following equation.
Toff (i) = (Toffup−Toffdown) × Foff + Toff (i−1)
Toffup: Increase in fuel temperature in the fuel tank 11 per calculation cycle
Toffdown: Fuel temperature drop in the fuel tank 11 per calculation cycle
Foff: Correction coefficient
Toff (i-1): Previous fuel temperature estimate
[0052]
Here, the fuel temperature increase Toffup while the engine is stopped is the fuel temperature increase due to the residual exhaust heat after the engine is stopped being transferred into the fuel tank 11. In a system equipped with an exhaust temperature sensor for detecting the exhaust temperature, the increase in fuel temperature due to exhaust residual heat may be estimated based on the output of the exhaust temperature sensor. However, in a system not equipped with an exhaust temperature sensor, the engine is stopped. What is necessary is just to calculate with a map or a numerical formula based on the elapsed time later.
[0053]
Further, the fuel temperature decrease Toffdown while the engine is stopped is calculated by a map or a mathematical expression based on the outside air temperature (or intake air temperature), or the outside air temperature (or intake air temperature) and the previous estimated fuel temperature Toff ( You may calculate by a map or a numerical formula based on the temperature difference with i-1).
[0054]
The correction coefficient Foff is a correction coefficient for correcting the current fuel temperature estimated value Toff (i) based on the fuel remaining amount in the fuel tank 11. Even when the outside air temperature is the same, it is considered that the amount of decrease in fuel temperature varies depending on the remaining amount of fuel in the fuel tank 11. In the present embodiment (1), the correction coefficient Foff is set to the reference value “1” when the fuel remaining amount in the fuel tank 11 is 50%, and the correction coefficient Foff is decreased as the remaining fuel amount decreases, thereby reducing the remaining fuel amount. As the value increases, the correction coefficient Foff is increased.
[0055]
The fuel temperature in the fuel tank 11 when the engine is stopped is estimated until the evaporative leak diagnosis is completed. Therefore, even when the engine is stopped, the main relay 22 is maintained in the ON state until the leak diagnosis is completed, and the control circuit 21, the atmospheric on-off valve 14, the purge control valve 16, the tank internal pressure sensor 17, and the fuel level sensor 18 are maintained. When the leak diagnosis is finished, the estimation of the fuel temperature is finished, and the main relay 22 is turned off, and the control circuit 21, the atmospheric on-off valve 14, the purge control valve 16, the tank internal pressure sensor 17, and the fuel level are turned off. The power supply to the sensor 18 is turned off.
[0056]
The processing contents of the routines shown in FIGS. 2 to 6 for executing the above-described fuel temperature estimation and evaporative leak diagnosis will be described below.
[0057]
The fuel temperature estimation routine shown in FIGS. 2 and 3 is executed every predetermined time (for example, every 10 seconds), and plays a role as a fuel temperature estimation device in the claims. When this routine is started, first, at step 101, it is determined whether or not the ignition switch 23 is turned on (ON), that is, whether or not the engine is running, and the ignition switch 23 is turned on (when the engine is running). ), The processing of steps 102 to 108 is executed, and the fuel temperature Ton (i) in the fuel tank 11 during engine operation is estimated as follows. First, in step 102, the current time is stored. By repeating this process every predetermined time (every 10 sec) during engine operation, the time when the ignition switch 23 is switched from on to off (time when the engine is stopped) is finally stored.
[0058]
Then, in the next step 103, using the fuel temperature increase calculation map MAP1 using the engine speed NE and the intake pipe pressure PM as parameters, the engine operation according to the current engine speed NE and the intake pipe pressure PM is being performed. The fuel temperature increase Tonup per calculation cycle (10 sec) is calculated. The processing of step 103 plays a role corresponding to the fuel temperature rise estimation means in the claims.
[0059]
Thereafter, the routine proceeds to step 104, where the engine corresponding to the current vehicle speed SPD and intake air temperature TA is used using the fuel temperature decrease calculation map MAP2 using the vehicle speed SPD and the intake air temperature TA (detected value of the intake air temperature sensor 20) as parameters. A fuel temperature drop Tondown per calculation cycle (10 sec) during operation is calculated. The processing in step 104 plays a role corresponding to the fuel temperature decrease estimation means in the claims.
[0060]
Thereafter, the process proceeds to step 105, and the current fuel is calculated using the correction coefficient calculation map MAP3 having the remaining fuel amount LFG (detected value of the fuel level sensor 18) and the previous estimated fuel temperature value Ton (i-1) as parameters. A correction coefficient Fon corresponding to the remaining amount LFG and the previous estimated fuel temperature value Ton (i-1) is calculated. In the next step 106, the estimated fuel temperature value Ton during engine operation is calculated using the fuel temperature increase Tonup, fuel temperature decrease Tondown, correction coefficient Fon, and previous fuel temperature estimated value Ton (i-1). (i) is calculated by the following equation.
Ton (i) = (Tonup−Tondown) × Fon + Ton (i−1)
[0061]
At this time, the initial value Ton (0) of the previous estimated fuel temperature value Ton (i-1) is set by a starting fuel temperature initial value setting routine of FIG.
[0062]
After calculating the estimated fuel temperature value Ton (i), the routine proceeds to step 107, where the estimated fuel temperature value Ton (i) is processed by the following equation to obtain the final estimated fuel temperature value Ton (i).
Ton (i) = Ton (i) × 0.05 + Ton (i−1) × 0.95
[0063]
The processes in steps 105 to 107 serve as fuel temperature estimation means and correction means in the claims.
[0064]
In the next step 108, the estimated fuel temperature value Ton (i) is stored as the initial value Toff (0) of the estimated fuel temperature value Toff after the engine is stopped, and this routine is terminated.
[0065]
While the engine is operating, the fuel temperature estimation value Ton (i) is updated every predetermined time (every 10 sec) by repeating the processing of steps 102 to 108 described above every predetermined time (every 10 sec). The stored value of the initial value Toff (0) of the estimated fuel temperature value Toff after the stop is rewritten with the latest estimated fuel temperature value Ton (i). Thereby, the estimation of the fuel temperature Toff after the engine is stopped uses the fuel temperature estimated value Ton (i) estimated last just before the engine is stopped as the initial value Toff (0).
[0066]
Thereafter, when the ignition switch 23 is turned off (OFF) and the engine is stopped, it is determined as “No” in Step 101, and the process proceeds to Step 109 in the step of FIG. 3 to determine whether the main relay 22 is in an ON state. If the main relay 22 is in an ON state, the processing of steps 110 to 114 is executed to stop the engine. The fuel temperature Toff (i) in the fuel tank 11 is estimated as follows.
[0067]
First, in step 110, calculation during engine stop according to the elapsed time time after the engine stop is performed using the fuel temperature increase calculation map MAP4 using the elapsed time time (measured value of the soak timer 25) after the engine stop as a parameter. The fuel temperature increase Toffup per cycle (10 sec) is calculated. The processing of step 110 plays a role corresponding to the fuel temperature rise estimation means in the claims.
[0068]
After this, the routine proceeds to step 111, where the fuel temperature decrease Toffdown per calculation cycle (10 sec) during engine stop according to the current intake air temperature TA using the fuel temperature decrease calculation map MAP5 using the intake air temperature TA as a parameter. Is calculated. The process of step 111 plays a role corresponding to the fuel temperature decrease estimation means in the claims.
[0069]
Thereafter, the process proceeds to step 112, and the correction coefficient Foff corresponding to the current fuel remaining amount LFG is calculated using the correction coefficient calculation map MAP6 using the fuel remaining amount LFG as a parameter. In the next step 113, the estimated fuel temperature Toff while the engine is stopped using the fuel temperature increase Toffup, the fuel temperature decrease Toffdown, the correction coefficient Foff, and the previous fuel temperature estimated value Toff (i-1). (i) is calculated by the following equation.
Toff (i) = (Toffup−Toffdown) × Foff + Toff (i−1)
[0070]
At this time, the initial value Toff (0) of the previous estimated fuel temperature value Toff (i-1) is the last estimated fuel temperature value Ton (i) immediately before the engine stop stored in step 108 of FIG. Use.
[0071]
After calculation of the estimated fuel temperature value Toff (i), the process proceeds to step 114 where the estimated fuel temperature value Toff (i) is smoothed according to the following equation to obtain the final estimated fuel temperature value Toff (i).
Toff (i) = Toff (i) × 0.05 + Toff (i−1) × 0.95
The processing of these steps 112 to 114 serves as fuel temperature estimation means and correction means in the claims.
[0072]
On the other hand, the starting fuel temperature initial value setting routine of FIG. 4 is started when the ignition switch 23 is turned on (when the control circuit 21 is turned on). When this routine is started, first, at step 201, an initial fuel temperature value Ton (0) at the time of engine start is calculated by the following equation.
Ton (0) = Toff (0) -ΔToff
[0073]
Here, Toff (0) is the estimated fuel temperature value Ton (i) last estimated immediately before the previous engine stop, and uses the value stored in step 108 of FIG. ΔToff is a fuel temperature decrease amount due to heat radiation from the previous engine stop to the current engine start. This fuel temperature decrease amount ΔToff is set by a map or the like according to the elapsed time from the previous engine stop to the current engine start and the intake air temperature (outside air temperature). For example, when the intake air temperature (outside air temperature) is 25 ° C., the fuel temperature decrease amount ΔToff is set at a rate of about 1 ° C./hour.
[0074]
In this embodiment (1), since the fuel temperature Toff is estimated until the evaporative leak diagnosis is completed even when the engine is stopped, the initial fuel temperature value Ton (0) at the time of engine start is Alternatively, the fuel temperature estimated value Toff (i) estimated last may be used to calculate the following equation.
Ton (0) = Toff (i) −ΔToff ′
[0075]
Here, ΔToff ′ is a fuel temperature decrease amount due to heat radiation from the end of fuel temperature estimation (end of leak diagnosis) to the current engine start. This fuel temperature drop amount ΔToff ′ may be set by a map or the like according to the elapsed time from the end of fuel temperature estimation (end of leak diagnosis) to the current engine start and the intake air temperature (outside air temperature).
[0076]
After calculating the initial fuel temperature value Ton (0), the routine proceeds to step 202, where the initial fuel temperature value Ton (0) is compared with the intake air temperature TA (outside air temperature), and the initial fuel temperature value Ton (0) is the intake air temperature TA ( If it is lower than the outside air temperature), the routine proceeds to step 203, where the fuel temperature initial value Ton (0) is set to the same temperature as the intake air temperature TA (outside air temperature). On the other hand, if the initial fuel temperature value Ton (0) calculated in step 201 is equal to or higher than the intake air temperature TA (outside air temperature), the initial fuel temperature value Ton (0) is used as the initial fuel temperature value at the time of engine start. Use.
[0077]
Next, the processing contents of the evaporation leak diagnosis routine of FIGS. 5 and 6 will be described. This routine is a routine for executing an evaporative leak diagnosis when a predetermined leak diagnosis execution condition is satisfied while the engine is running and the engine is stopped. It is activated (for example, every 50 msec) and serves as an abnormality diagnosis means in the claims.
[0078]
When this routine is started, first, at step 301, it is determined whether or not the ignition switch 23 is turned on (ON), that is, whether or not the engine is running, and the ignition switch 23 is turned on (when the engine is running). ), It is determined by the determination processing in steps 302 to 305 whether or not a leakage diagnosis execution condition during engine operation is satisfied. The leak diagnosis execution condition during engine operation is that all of the following four conditions (1) to (4) are satisfied.
[0079]
(1) A predetermined time, for example, 100 sec has elapsed since the engine was started (step 302).
(2) The current cooling water temperature is a predetermined temperature, for example, 70 ° C. or more (step 303).
(3) The current intake air temperature (outside air temperature) is lower than a predetermined temperature, for example, 50 ° C. (step 304).
(4) The current estimated fuel temperature value Ton (i) is lower than a predetermined temperature, for example, 40 ° C. (step 305).
[0080]
The above conditions (1) and (2) are conditions for executing a leak diagnosis in a stable engine operating state after engine warm-up. Also, if the outside air temperature or the fuel temperature in the fuel tank 11 becomes too high, the amount of evaporation gas generated in the fuel tank 11 becomes too large, and the change in the fuel tank internal pressure when there is a small amount of leak and the change in the fuel tank internal pressure during normal operation. The above conditions (3) and (4) ensure the difference between the change in the fuel tank internal pressure when there is a small amount of leak and the change in the internal pressure of the fuel tank during normal operation. It is a condition to do.
[0081]
If any one of these four conditions (1) to (4) is not satisfied, the leak diagnosis execution condition is not satisfied, and this routine is terminated without executing the leak diagnosis.
[0082]
On the other hand, if all of the four conditions (1) to (4) are satisfied, the leak diagnosis execution condition is satisfied, and the leak diagnosis process after step 306 is executed as follows. First, in step 306, the atmospheric on-off valve 14 is closed to seal the evaporation system (at this time, the purge control valve 16 is kept closed). Thereafter, the process proceeds to step 307, where the purge control valve 16 is opened to introduce a negative pressure into the evaporation system from the engine intake system, and the purge control valve 16 is closed when the internal pressure of the fuel tank decreases to a predetermined pressure. End the negative pressure introduction and seal the evaporation system again.
[0083]
Thereafter, the process proceeds to step 308, and the fuel tank internal pressure change amount ΔP (the change amount of the detected value of the tank internal pressure sensor 17) until a predetermined time (for example, 15 seconds) elapses after the introduction of the negative pressure is measured. In the next step 309, the fuel tank internal pressure change amount ΔP is compared with a preset leak judgment value K1, and if the fuel tank internal pressure change amount ΔP is less than or equal to the leak judgment value K1, it is determined that there is no leak (normal). To end this routine.
[0084]
If the fuel tank internal pressure change amount ΔP is larger than the leak judgment value K1, it is judged that a leak has occurred (abnormal), and the routine proceeds to step 310 where a warning lamp (not shown) is lit to warn the driver. Then, the abnormal code is stored in a backup RAM (not shown) of the control circuit 21, and further, in the next step 311, the evaporation system is continuously sealed, and this routine is terminated.
[0085]
On the other hand, when the ignition switch 23 is turned off (OFF) and the engine is stopped, “No” is determined in step 301, and the leak diagnosis execution condition while the engine is stopped is determined by the determination processing in steps 312 to 315 in FIG. 6. It is determined whether it is established. The leak diagnosis execution condition when the engine is stopped is that all of the following four conditions (1) to (4) are satisfied.
[0086]
(1) A predetermined time, for example, 1000 seconds has elapsed since the engine was stopped (step 312).
(2) The current cooling water temperature is a predetermined temperature, for example, 70 ° C. or more (step 313).
(3) The current intake air temperature (outside air temperature) is lower than a predetermined temperature, for example, 50 ° C. (step 314).
(4) The fuel temperature initial value Toff (0) after the engine is stopped [the value last stored in step 108 of FIG. 2 immediately before the engine is stopped] is a predetermined temperature, for example, 35 ° C. or more (step 315).
[0087]
Immediately after the engine is stopped, the temperature of the exhaust system is high and the fuel temperature in the fuel tank 11 continues to rise for a while due to the heat. Therefore, the condition (1) waits until the fuel temperature in the fuel tank 11 starts to decrease. This is a condition for starting leak diagnosis. The condition (2) is a condition for starting the leak diagnosis in a state where the fuel temperature in the fuel tank 11 is sufficiently increased by the exhaust heat.
[0088]
If the outside air temperature is too high or the fuel temperature in the fuel tank 11 is too low, the difference between the fuel temperature in the fuel tank 11 and the outside air temperature is reduced, and the fuel temperature is reduced due to heat dissipation while the engine is stopped. Therefore, it becomes difficult to secure the amount of fuel temperature decrease necessary for leak diagnosis. In order to avoid this, the above conditions (3) and (4) are conditions for securing the amount of fuel temperature decrease necessary for the leak diagnosis.
[0089]
If any of these four conditions (1) to (4) does not satisfy one of the conditions, the leak diagnosis execution condition is not satisfied. At this time, if the conditions (2) and (4) (steps 313 and 315) are once determined to be “No”, they can be determined to be “Yes” even if time elapses during the current engine stop. Therefore, the process proceeds to step 321 where the main relay 22 is turned off to turn off the power supply to the control circuit 21 and the routine is terminated. In addition, since the conditions (1) and (3) (steps 312 and 314) are once determined as “No”, it may be determined as “Yes” after a lapse of time. This routine ends without turning off the relay 22 (OFF).
[0090]
On the other hand, if all of the four conditions (1) to (4) are satisfied, the leak diagnosis execution condition is satisfied, and the leak diagnosis process after step 316 is executed as follows. First, in step 316, the atmospheric on-off valve 14 is closed to seal the evaporation system (at this time, the purge control valve 16 is kept closed). Thereafter, the process proceeds to step 317, and the fuel tank internal pressure change ΔP (the change in the detected value of the tank internal pressure sensor 17) from when the evaporation system is sealed until the estimated fuel temperature Toff decreases by a predetermined temperature (for example, 10 ° C.) is measured. To do.
[0091]
Thereafter, the routine proceeds to step 318, where the fuel tank internal pressure change amount ΔP is compared with a preset leak judgment value K2, and an evaporative leak diagnosis is performed. As shown in FIG. 7, when a leak occurs in the evaporation system, the fuel tank internal pressure change amount ΔP during the leak diagnosis period becomes very small. When there is no leak, the fuel tank internal pressure change amount ΔP increases to some extent. . From such characteristics, if the fuel tank internal pressure change amount ΔP is greater than or equal to the leak determination value K2, it is determined that there is no leak (normal), the process proceeds to step 321, the main relay 22 is turned off (OFF), and the control circuit The power supply to 21 etc. is turned off, and this routine is finished.
[0092]
On the other hand, if the fuel tank internal pressure change ΔP is smaller than the leak judgment value K2, it is judged that a leak has occurred (abnormal), and the routine proceeds to step 319, where a warning lamp (not shown) is lit to warn the driver. At the same time, the abnormal code is stored in a backup RAM (not shown) of the control circuit 21. Then, in the next step 320, the atmospheric on-off valve 14 is opened to release the sealing of the evaporation system, and then the process proceeds to step 321 where the main relay 22 is turned off to supply power to the control circuit 21 and the like. Is turned off and this routine is terminated.
[0093]
In the present embodiment (1) described above, the fuel temperature can be determined during engine operation and engine stop without providing a fuel temperature sensor, and the demand for cost reduction can be satisfied. In addition, even if the fuel temperature sensor is not provided, the evaporation leak diagnosis can be performed in consideration of the fuel temperature, and the leak diagnosis accuracy can be improved.
[0094]
Furthermore, in the present embodiment (1), the leak diagnosis of the evaporative system is performed in consideration of the fuel temperature while the engine is stopped in addition to the operation of the engine, so the number of leak diagnosis can be increased, The requirement for early detection of leaks can also be met. However, according to the present invention, the evaporative leak diagnosis may be performed only during either engine operation or engine stop.
[0095]
In the present embodiment (1), the leakage diagnosis is performed based on the fuel tank internal pressure change ΔP from when the evaporation system is closed while the engine is stopped until the estimated fuel temperature Toff drops to a predetermined temperature. The evaporative system leak diagnosis may be performed based on the rate of decrease (inclination of decrease) in the estimated fuel temperature Toff and the rate of change in the internal pressure of the fuel tank (inclination of change) within a predetermined period from when the system is sealed. In short, the leakage diagnosis of the evaporation system may be performed based on the relationship between the change in the estimated fuel temperature Toff estimated while the engine is stopped and the change in the fuel tank internal pressure. Further, the method of leak diagnosis during engine operation may be changed as appropriate.
[0096]
[Embodiment (2)]
In the above embodiment (1), the estimated fuel temperature estimated during engine operation or engine stop is used for the evaporative leak diagnosis. However, the use of the estimated fuel temperature is limited to the evaporative leak diagnosis. Instead, it may be used for engine control such as air-fuel ratio control (fuel injection amount control).
[0097]
Further, the present invention may be applied to a system including a fuel temperature sensor that detects the fuel temperature in the fuel tank 11. Hereinafter, an embodiment (2) of the present invention that embodies this will be described with reference to FIGS. In the present embodiment (2), the estimated fuel temperature value is used for abnormality diagnosis of the fuel temperature sensor.
[0098]
As shown in FIG. 9, if the fuel temperature sensor is normal, the error between the fuel temperature estimated value T and the detected value Tsen of the fuel temperature sensor is small, but the fuel temperature sensor fails and the detected value Tsen of the fuel temperature sensor. Becomes an abnormal value, an error between the estimated fuel temperature value T and the detected value Tsen of the fuel temperature sensor increases. Therefore, in the present embodiment (2), abnormality diagnosis of the fuel temperature sensor is performed based on the error between the fuel temperature estimated value T and the detected value Tsen of the fuel temperature sensor by the fuel temperature sensor abnormality diagnosis routine of FIG.
[0099]
The fuel temperature sensor abnormality diagnosis routine of FIG. 8 is started every predetermined time (for example, every 50 msec) after the ignition switch 23 is turned on, and plays a role as abnormality diagnosis means in the claims. The method for estimating the fuel temperature is the same as that in the first embodiment (1).
[0100]
When this routine is started, first, in step 401, it is determined whether or not a predetermined time (for example, 5 seconds) has elapsed since the engine was started. If not, the process proceeds to step 402, where the initial value of the estimated fuel temperature value is determined. The fuel temperature estimated value T at that time is set as Tst, and in the next step 403, the fuel temperature sensor detected value Tsen at that time is set as the initial value Tsenst of the fuel temperature sensor detected value.
[0101]
Thereafter, after a predetermined time (for example, 5 seconds) has elapsed since the engine is started, the process proceeds from step 401 to step 404, and whether or not the increase amount (T-Tst) of the estimated fuel temperature value after the engine is started is, for example, 10 ° C. or more. If it is less than 10 ° C., this routine is terminated without performing the subsequent processing.
[0102]
Thereafter, when the increase amount (T-Tst) of the estimated fuel temperature value after starting the engine becomes 10 ° C. or more, the routine proceeds to step 405 and the increase amount (Tsen−Tsenst) of the detected fuel temperature sensor value after starting the engine. Is determined to be less than 5 ° C., for example. If the increase amount (Tsen-Tsenst) of the detected value of the fuel temperature sensor after the engine start is 5 ° C. or more, the increase amount of the detected value of the fuel temperature sensor (Tsen−Tsenst) and the increase amount of the estimated fuel temperature value (T -Tst) is within the normal error range, it is determined that the fuel temperature sensor is normal, and this routine is terminated.
[0103]
On the other hand, if the increase amount (Tsen-Tsenst) of the fuel temperature sensor detection value after engine startup is less than 5 ° C., the increase amount of the fuel temperature sensor detection value (Tsen-Tsenst) and the increase amount of the estimated fuel temperature value Since the error with respect to (T-Tst) exceeds the normal error range, it is determined that the fuel temperature sensor is abnormal, and the routine proceeds to step 406 where a warning lamp (not shown) is lit and the driver is turned on. And the abnormal code is stored in a backup RAM (not shown) of the control circuit 21. In the next step 407, leak diagnosis is prohibited and this routine is terminated.
[0104]
In this embodiment (2), when performing an evaporative system leak diagnosis, the detected value of the fuel temperature sensor is used instead of the estimated fuel temperature value, and the evaporative system is used in the same manner as in the first embodiment (1). Perform a leak diagnosis.
[0105]
In the present embodiment (2) described above, the fuel temperature sensor abnormality diagnosis is performed using the estimated fuel temperature value, so that the reliability of the system including the fuel temperature sensor can be improved.
[0106]
In this embodiment (2), the abnormality diagnosis of the fuel temperature sensor is performed from the relationship between the increase amount of the detected value of the fuel temperature sensor and the estimated increase value of the fuel temperature after the engine is started. An abnormality diagnosis of the fuel temperature sensor may be performed from the relationship between the change amount of the detected value of the fuel temperature sensor and the change amount of the estimated fuel temperature value. Alternatively, at any time during engine operation or after engine stop, an error between the estimated fuel temperature value and the detected value of the fuel temperature sensor is determined, and whether or not the error exceeds the normal error range, the fuel temperature sensor The presence or absence of an abnormality may be determined.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an evaporation gas purge system in an embodiment (1) of the present invention.
FIG. 2 is a flowchart (part 1) showing a flow of processing of a fuel temperature estimation routine of the embodiment (1).
FIG. 3 is a flowchart (part 2) showing the flow of processing of the fuel temperature estimation routine of the embodiment (1).
FIG. 4 is a flowchart showing a processing flow of a starting fuel temperature initial value setting routine according to the embodiment (1).
FIG. 5 is a flowchart (part 1) showing a flow of processing of an evaporative leak diagnosis routine of the embodiment (1).
FIG. 6 is a flowchart (part 2) showing a flow of processing of an evaporative leak diagnosis routine of the embodiment (1).
FIG. 7 is a time chart showing an example of fuel temperature estimation and evaporation system leak diagnosis in the embodiment (1).
FIG. 8 is a flowchart showing a flow of processing of a fuel temperature sensor abnormality diagnosis routine of the embodiment (2).
FIG. 9 is a time chart showing the relationship between the estimated fuel temperature value and the detected value of the fuel temperature sensor in the embodiment (2).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Fuel tank, 12 ... Evaporative passage, 13 ... Canister, 14 ... Atmospheric on-off valve, 15 ... Purge passage, 16 ... Purge control valve, 17 ... Tank internal pressure sensor, 18 ... Fuel level sensor, 19 ... Water temperature sensor, 20 ... Intake air temperature sensor, 21 ... control circuit (fuel temperature rise estimation means, fuel temperature fall estimation means, fuel temperature estimation means, correction means, abnormality diagnosis means), 22 ... main relay, 23 ... ignition switch, 24 ... backup power supply 25 ... Soak timer.

Claims (10)

In a fuel temperature estimation device for estimating a fuel temperature in a fuel tank during operation of an internal combustion engine,
A fuel temperature increase estimation means for estimating an increase in fuel temperature in the fuel tank due to exhaust heat being transferred into the fuel tank based on the operation state during operation of the internal combustion engine;
Fuel temperature decrease estimation means for estimating a decrease in fuel temperature in the fuel tank based on vehicle speed and / or intake air temperature or information correlated therewith;
And a fuel temperature estimating means for updating the estimate of the current fuel temperature based on the lowering amount and increase in the fuel temperature estimated by the fuel temperature rise estimation means and the fuel temperature lowering amount estimating means,
The fuel temperature estimation means includes a fuel temperature estimated value estimated at the time of the previous internal combustion engine operation stop, an elapsed time from the previous internal combustion engine operation stop to the current internal combustion engine start, and an outside air temperature or information correlated therewith. An initial value of the fuel temperature at the start of the internal combustion engine is estimated based on   The fuel temperature estimation device according to claim 1, wherein the fuel temperature increase estimation means estimates an increase in fuel temperature in the fuel tank based on the rotational speed and / or load of the internal combustion engine. Applied to a fuel system configured to return an excess of fuel sent from the fuel tank to a fuel injection valve by a fuel pump;
The fuel temperature rise estimation means estimates the fuel temperature rise due to the fuel returned from the fuel injector to the fuel tank in addition to the fuel temperature rise in the fuel tank due to exhaust heat. The fuel temperature estimation device according to claim 1, wherein   The present invention is applied to a fuel system in which a fuel pump is arranged in the fuel tank, and the fuel temperature increase estimation means also estimates an increase in fuel temperature in the fuel tank due to heat generated by the fuel pump. The fuel temperature estimation device according to any one of claims 1 to 3.   2. The fuel temperature estimating means comprises a correcting means for correcting a current fuel temperature estimated value based on a fuel remaining amount in the fuel tank and / or a previous fuel temperature estimated value. The fuel temperature estimation apparatus in any one of thru | or 4. In a fuel temperature estimation device for estimating a fuel temperature in a fuel tank during operation of an internal combustion engine,
A fuel temperature increase estimation means for estimating an increase in fuel temperature in the fuel tank due to exhaust heat being transferred into the fuel tank based on the operation state during operation of the internal combustion engine;
Fuel temperature decrease estimation means for estimating a decrease in fuel temperature in the fuel tank based on vehicle speed and / or intake air temperature or information correlated therewith;
Fuel temperature estimation for executing a fuel temperature estimation calculation for updating an estimated value of the current fuel temperature based on the fuel temperature increase and decrease estimated by the fuel temperature increase estimation means and the fuel temperature decrease estimation means Means and
The fuel temperature estimation means includes a fuel temperature estimated value estimated when the internal combustion engine was stopped last time, an elapsed time from the previous stop of the internal combustion engine operation to the start of the current fuel temperature estimation calculation, an outside air temperature, or a correlation therewith. A fuel temperature estimation device for estimating a fuel temperature at the start of a current fuel temperature estimation calculation based on certain information . An abnormality diagnosis device comprising: the fuel temperature estimation device according to any one of claims 1 to 6; and an abnormality diagnosis unit that performs abnormality diagnosis of the evaporation gas purge system during operation of the internal combustion engine.
The abnormality diagnosis device, wherein the abnormality diagnosis unit uses the estimated fuel temperature estimated by the fuel temperature estimation device as an abnormality diagnosis execution condition determination parameter and / or an abnormality diagnosis parameter.   The abnormality diagnosis apparatus according to claim 7, wherein one of the abnormality diagnosis execution conditions is that the estimated fuel temperature value estimated by the fuel temperature estimation apparatus is equal to or lower than a predetermined temperature. In an abnormality diagnosis device that performs abnormality diagnosis of a fuel temperature sensor that detects a fuel temperature in a fuel tank,
The fuel temperature estimation device according to any one of claims 1 to 6,
Abnormality diagnosis means comprising abnormality diagnosis means for performing abnormality diagnosis of the fuel temperature sensor based on a relationship between a fuel temperature estimation value estimated by the fuel temperature estimation device and a detection value of the fuel temperature sensor apparatus.   The abnormality diagnosis unit performs abnormality diagnosis of the fuel temperature sensor based on a relationship between a change amount of a fuel temperature estimated value within a predetermined period and a change amount of a detection value of the fuel temperature sensor. 9. The abnormality diagnosis device according to 9.

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