JP6433770B2 - Fuel temperature suppression control method and common rail fuel injection control device - Google Patents

Description

  The present invention relates to a control for suppressing and preventing an increase in fuel temperature in a common rail fuel injection control device, and more particularly to a device that improves control reliability and reliability.

  The so-called common rail type fuel injection control device pressurizes fuel by a high pressure pump, pumps and accumulates pressure to a common rail which is an accumulator, and supplies the accumulated high pressure fuel to the fuel injection valve, whereby an internal combustion engine using the fuel injection valve It is well known as a fuel that is capable of injecting high-pressure fuel into the fuel cell and is excellent in fuel consumption and emission characteristics (see, for example, Patent Document 1).

  In such a common rail type fuel injection control device, a pressure control valve for discharging the high pressure fuel of the common rail to the fuel tank as needed is provided, and the outlet side of the pressure control valve is usually connected to the fuel tank. However, in recent years, especially in cold district vehicles, the fuel temperature can be quickly brought to an appropriate range after starting the engine in order to avoid adverse effects such as poor lubrication due to increased fuel viscosity in winter. For the purpose of raising, there is a configuration in which an outlet side of a pressure control valve is connected to a filter inlet side provided between a fuel tank and a high-pressure pump.

JP2013-194718A (Page 5-14, FIGS. 1-8)

However, with the recent increase in rail pressure, the temperature of the return fuel that is returned to the fuel tank rises markedly depending on the operating conditions, and problems such as performance deterioration of parts due to high fuel temperature cannot be ignored. It is.
In particular, as described above, in the configuration in which the high-pressure fuel discharged through the pressure control valve is returned to the filter inlet side, the temperature of the fuel flowing into the high-pressure pump is further increased, and the above-described high-temperature fuel is used. There is a problem that adverse effects on such parts are accelerated.

  The present invention has been made in view of the above circumstances, and has a relatively simple configuration, and suppresses and prevents an unnecessary temperature rise of fuel supplied to the high-pressure pump, thereby improving the reliability of the apparatus. A suppression control method and a common rail fuel injection control device are provided.

In order to achieve the above object of the present invention, the charge temperature suppression control method according to the present invention includes:
The fuel in the fuel tank is pressurized and pumped to the common rail by the high-pressure pump, and high-pressure fuel can be injected into the engine via the fuel injection valve connected to the common rail, and surplus fuel in the common rail is supplied to the high-pressure pump. A fuel temperature suppression control method in a common rail fuel injection control device configured to be capable of being discharged between the fuel tank and the high-pressure pump via a pressure control valve provided on the downstream side,
When the inlet temperature of the high-pressure pump exceeds the inlet control reference temperature, the discharge flow rate of the electric low-pressure pump that sends the fuel in the fuel tank to the high-pressure pump is set to the inlet temperature of the high-pressure pump and the inlet control reference. It is configured to increase according to the difference with temperature.
In order to achieve the above object of the present invention, a common rail fuel injection control device according to the present invention includes:
The fuel in the fuel tank is pressurized and pumped to the common rail by the high-pressure pump, and high-pressure fuel can be injected into the engine via the fuel injection valve connected to the common rail, and surplus fuel in the common rail is supplied to the high-pressure pump. A common rail fuel that is configured to be capable of being discharged between the fuel tank and the high-pressure pump via a pressure control valve provided on the downstream side, and is provided with an electronic control unit that enables drive control of the pressure control valve. An injection control device,
The electronic control unit is
When it is determined that the inlet temperature of the high-pressure pump exceeds the inlet control reference temperature, the discharge flow rate of the electric low-pressure pump that sends the fuel in the fuel tank to the high-pressure pump is set as the inlet temperature of the high-pressure pump. It is configured to increase in accordance with the difference from the inlet control reference temperature.

  According to the present invention, when the inlet temperature of the high pressure pump exceeds a predetermined reference temperature, the discharge amount of the electric low pressure pump is increased, and the temperature of the return fuel from the pressure control valve, which is the main cause of the fuel temperature rise, is increased. Since it can be lowered with the fuel in the fuel tank at a temperature lower than that, it is possible to reliably suppress and prevent unnecessary temperature rise of the fuel supplied to the high-pressure pump with a relatively simple configuration. It is possible to provide a highly reliable common rail fuel injection control device.

It is a block diagram which shows the structural example of the common rail type | mold fuel-injection control apparatus in embodiment of this invention. It is a flowchart which shows the procedure in the 1st Example of the fuel temperature suppression control process performed by the electronic control unit used for the common rail type fuel-injection control apparatus in embodiment of this invention. It is a flowchart which shows the procedure in the 2nd Example of the fuel temperature suppression control process performed by the electronic control unit used for the common rail type fuel-injection control apparatus in embodiment of this invention. It is a flowchart which shows the procedure in the 3rd Example of the fuel temperature suppression control process performed by the electronic control unit used for the common rail type fuel-injection control apparatus in embodiment of this invention. It is a flowchart which shows the procedure in the 4th Example of the fuel temperature suppression control process performed by the electronic control unit used for the common rail type fuel-injection control apparatus in embodiment of this invention.

Embodiments of the present invention will be described below with reference to FIGS. 1 to 5.
The members and arrangements described below do not limit the present invention and can be variously modified within the scope of the gist of the present invention.
First, a schematic configuration example of a common rail fuel injection control device to which a fuel temperature suppression control method according to an embodiment of the present invention is applied will be described with reference to FIG.
The common rail fuel injection control device according to the embodiment of the present invention includes a high pressure pump 1 that pumps high pressure fuel, a common rail 2 that stores high pressure fuel pumped by the high pressure pump 1, and a high pressure supplied from the common rail 2. A plurality of fuel injection valves 3-1 to 3-n for supplying fuel to cylinders of an engine (not shown), and an electronic control unit (FIG. 1) for executing fuel injection control processing, fuel temperature suppression control described later, and the like. In this example, the main component is “ECU”.

In this configuration, the fuel in the fuel tank 5 is pumped up by the electric low-pressure pump 6 and supplied to the high-pressure pump 1 through the filter 7.
In the embodiment of the present invention, the fuel tank 5 contains a sub-tank 8 therein, and an electric low-pressure pump 6 is disposed in the sub-tank 8.
The sub-tank 8 is partially opened at the lower side, and the first return passage 21 from the fuel injection valves 3-1 to 3-n is connected to the opening via the jet pump 9. It has a configuration.
Such a jet pump 9 has a well-known configuration, and is an electric low-pressure pump even if the liquid level of the fuel in the fuel tank 5 is inclined due to vehicle inclination or acceleration / deceleration during traveling. The suction port 6 is always immersed in the fuel to prevent air from being sucked.

On the other hand, an electromagnetically controlled pressure control valve 10 is provided at a portion of the common rail 2 where excess fuel is discharged. The pressure control valve 10 has a second end connected to the inlet side of the filter 7. Return passage 22 is connected, and excess fuel in the common rail 2 is returned to the filter 7 via the pressure control valve 10.
The surplus fuel from the high-pressure pump 1 is returned to the fuel tank 5 via the third return passage 23 connected between the high-pressure pump 1 and the first return passage 21. Yes.

The fuel injection valves 3-1 to 3-n are provided for each cylinder of an engine (not shown), receive high-pressure fuel from the common rail 2, and perform fuel injection by injection control by the electronic control unit 4. It is like that.
The electronic control unit 4 includes, for example, a microcomputer (not shown) having a known and well-known configuration, a storage element (not shown) such as a RAM and a ROM, and a fuel injection valve 3- A circuit (not shown) for energizing and driving 1 to 3 -n, a circuit (not shown) for driving the electric low-pressure pump 6, and the like are configured as main components.

The electronic control unit 4 is provided near the inlet of the high-pressure pump 1 and receives a detection signal from a pump inlet temperature sensor 31 that detects the temperature of the fuel near the inlet, as well as the engine speed, the accelerator opening, the outside air. Various detection signals such as temperature and atmospheric pressure are input to be used for operation control of an engine (not shown), fuel injection control, and fuel temperature suppression control processing in the embodiment of the present invention. It has become.
In addition, a pump outlet temperature 32 for detecting the temperature of the fuel near the outlet of the high-pressure pump 1, a filter temperature sensor 33 for detecting the temperature of the fuel (filter temperature) in the filter 7, and the temperature of the fuel in the fuel tank 5. Tank temperature sensors 34 for detecting (tank temperature) are provided, and the output values of these temperature sensors are input to the electronic control unit 4 and used for fuel temperature suppression control processing described later. Yes.

  The pump outlet temperature sensor 32 is used in the second embodiment of the fuel temperature suppression control process, the filter temperature sensor 33 is used in the third embodiment of the fuel temperature suppression control process, and the tank temperature sensor 34 is used in the fuel temperature suppression control process. In the fourth embodiment of the control process, each is required, and is not essential except in the corresponding embodiment.

Next, the procedure in the first example of the fuel temperature suppression control process of the embodiment of the present invention executed by the electronic control unit 4 will be described with reference to FIG.
When processing by the electronic control unit 4 is started, first, a measured value of the pump inlet temperature is acquired (see step S102 in FIG. 2).
Here, the “pump inlet temperature” is the temperature of the fuel near the inlet of the high-pressure pump 1 and is the temperature detected by the pump inlet temperature sensor 31.
Accordingly, the output signal of the pump inlet temperature sensor 31 is temporarily stored in an appropriate storage area of the electronic control unit 4.

  Next, it is determined whether or not the pump inlet temperature obtained in step S102 exceeds a predetermined inlet control reference temperature (see step S104 in FIG. 2), and the pump inlet temperature exceeds a predetermined inlet control reference temperature. Is determined (YES), the process proceeds to step S106. On the other hand, if it is determined that the pump inlet temperature does not exceed the predetermined inlet control reference temperature (NO), step S108 is performed. The process will proceed.

In step S106, the discharge flow rate of the electric low-pressure pump 6 is increased.
That is, the electronic control unit 4 instructs the electric low-pressure pump 6 to specify the discharge amount according to the difference between the pump inlet temperature acquired in step S102 and the inlet control reference temperature, and the electric low-pressure pump 6 discharges the electric low-pressure pump 6. The amount of fuel will be increased.
Therefore, a large amount of fuel in the fuel tank 5 having a lower temperature than the pump inlet temperature flows into the inlet of the high-pressure pump 1 as compared with the temperature before that, which is one of the factors that increase the pump inlet temperature. The temperature of the return fuel from the second return passage 22 is lowered, and adverse effects such as component deterioration due to the increase in the fuel temperature are suppressed and prevented.
Note that as a result of increasing the discharge amount of the electric low-pressure pump 6 as described above, the amount of fuel flowing into the high-pressure pump 1 increases, but the surplus fuel is supplied from the third return passage 23 to the fuel tank 5. It is supposed to be returned.

For example, if the pump inlet temperature is Tpin and the inlet control reference temperature is Tpinst, the fuel amount Qp discharged from the electric low-pressure pump 6 in this step S106 is calculated by Qp = Q0 + α (Tpin−Tpinst) and the electronic control unit 4 It is supposed to be.
Here, “Q 0” is a necessary minimum flow rate that is the minimum value of the amount of fuel to be discharged from the electric low-pressure pump 6, and “α” is a calculation constant, both of which are specific to the electric low-pressure pump 6. It is determined based on test results and simulation results in consideration of various specifications.

On the other hand, in step S108, the electric low-pressure pump 6 is driven with the above-mentioned minimum required flow rate value.
After the process of step S106 or step S108 described above, the process returns to the main routine (not shown).

Next, the procedure in the second example of the fuel temperature suppression control process of the embodiment of the present invention executed by the electronic control unit 4 will be described with reference to FIG.
In the second embodiment, a pump outlet temperature sensor 32 for detecting the temperature of the fuel in the vicinity of the outlet of the high-pressure pump 1 (pump outlet temperature) is further provided in the configuration shown in FIG. It is assumed that.

  Further, step S204 in FIG. 3 corresponds to step S104 shown in FIG. 2, and step S208 in FIG. 3 corresponds to step S108 shown in FIG. Therefore, the detailed description will not be repeated here, and the following description will focus on the differences from the processing in FIG.

  When the processing by the electronic control unit 4 is started, first, as in step S102 (see FIG. 2), the measured value of the pump inlet temperature is acquired, and in the second embodiment, the pump outlet The temperature measurement value is acquired, and the data is temporarily stored in an appropriate storage area of the electronic control unit 4 (see step S202 in FIG. 3).

Next, in step S204, if it is determined that the pump inlet temperature does not exceed the predetermined inlet control reference temperature (in the case of NO), whether or not the pump outlet temperature exceeds the predetermined outlet control reference temperature is determined. If it is determined (see step S207 in FIG. 3) and it is determined that the pump outlet temperature exceeds the predetermined outlet control reference temperature (in the case of YES), the process proceeds to step S206, while the pump outlet temperature is If it is determined that the predetermined outlet control reference temperature is not exceeded (NO), the process proceeds to step S208.
The outlet control reference temperature is preferably determined based on test results and simulation results in consideration of specific specifications of the common rail fuel injection control device.

In step S206, unlike the previous step S106 (see FIG. 2), the discharge amount of the electric low-pressure pump 6 is increased according to the difference between the pump outlet temperature Tpout and the outlet control reference temperature Tpoutst.
That is, the fuel amount Qp discharged from the electric low-pressure pump 6 is calculated and calculated in the electronic control unit 4 by Qp = Q0 + α (Tpout−Tpoutst). The necessary minimum flow rate Q0 and the operation constant α are as described above in step S106.

  In the second embodiment, in addition to the pump inlet temperature, the pump outlet temperature is used to determine the flow rate increase of the electric low-pressure pump 6. For example, even if the pump inlet temperature sensor 31 fails, Since the necessity of increasing the flow rate of the electric low-pressure pump 6 can be determined based on the outlet temperature, fuel temperature control with higher reliability is performed as compared with the first embodiment.

Next, the procedure in the third example of the fuel temperature suppression control process of the embodiment of the present invention executed by the electronic control unit 4 will be described with reference to FIG.
The third embodiment is based on the premise that the filter temperature sensor 33 for detecting the temperature of the fuel in the filter 7 is further provided in the configuration shown in FIG.
Further, step S304 in FIG. 4 corresponds to step S104 shown in FIG. 2, and step S308 in FIG. 4 corresponds to step S108 shown in FIG. 2, and basically each has the same processing content. Therefore, the detailed description will not be repeated here, and the following description will focus on the differences from the processing in FIG.

  When the processing by the electronic control unit 4 is started, first, as in step S102 (see FIG. 2), the measured value of the pump inlet temperature is obtained, and in the third embodiment, the filter temperature is further increased. The measured value is acquired, and the data is temporarily stored in an appropriate storage area of the electronic control unit 4 (see step S302 in FIG. 4).

Next, when it is determined in step S304 that the pump inlet temperature does not exceed the predetermined inlet control reference temperature (in the case of NO), it is determined whether or not the filter temperature exceeds the predetermined filter control reference temperature. If it is determined that the filter temperature exceeds the predetermined filter control reference temperature (in the case of YES), the process proceeds to step S306 while the filter temperature is equal to the predetermined filter control temperature (see step S307 in FIG. 4). If it is determined that the control reference temperature has not been exceeded (NO), the process proceeds to step S308.
The predetermined filter control reference temperature is preferably determined based on test results and simulation results in consideration of specific specifications of the common rail fuel injection control device.

In step S306, the discharge amount of the electric low-pressure pump 6 is increased according to the difference between the filter temperature Tfl and the filter control reference temperature Tflst, unlike the previous step S106 (see FIG. 2).
That is, the fuel amount Qp discharged from the electric low-pressure pump 6 is calculated and calculated in the electronic control unit 4 by Qp = Q0 + α (Tfl−Tflst). The necessary minimum flow rate Q0 and the operation constant α are as described above in step S106.
As in the second embodiment, the third embodiment can determine whether the flow rate of the electric low-pressure pump 6 needs to be increased by the filter temperature even if the pump inlet temperature sensor 31 breaks down. In contrast, the fuel temperature control with higher reliability is performed.

Next, the procedure in the fourth example of the fuel temperature suppression control process of the embodiment of the invention executed by the electronic control unit 4 will be described with reference to FIG.
The fourth embodiment is based on the premise that a tank temperature sensor 34 for detecting the temperature of the fuel in the fuel tank 5 is further provided in the structure shown in FIG. .
Further, step S404 in FIG. 5 corresponds to step S104 shown in FIG. 2, and step S408 in FIG. 5 corresponds to step S108 shown in FIG. Therefore, the detailed description will not be repeated here, and the following description will focus on the differences from the processing in FIG.

  When the processing by the electronic control unit 4 is started, first, as in step S102 (see FIG. 2), the measurement value of the pump inlet temperature is obtained. In the fourth embodiment, the tank temperature is further increased. The measured value is acquired, and the data is temporarily stored in an appropriate storage area of the electronic control unit 4 (see step S402 in FIG. 4).

Next, when it is determined in step S404 that the pump inlet temperature does not exceed the predetermined inlet control reference temperature (in the case of NO), the tank temperature that is the temperature in the fuel tank 5 is the predetermined tank control reference temperature. Is determined (see step S407 in FIG. 5), and if it is determined that the tank temperature exceeds the predetermined tank control reference temperature (in the case of YES), the process proceeds to step S406. On the other hand, when it is determined that the tank temperature does not exceed the predetermined tank control reference temperature (in the case of NO), the process proceeds to step S408.
The predetermined tank control reference temperature is preferably determined based on test results and simulation results in consideration of specific specifications of the common rail fuel injection control device.

In step S406, the discharge amount of the electric low-pressure pump 6 is increased according to the difference between the tank temperature Ttan and the tank control reference temperature Ttanst, unlike the previous step S106 (see FIG. 2).
That is, the fuel amount Qp discharged from the electric low-pressure pump 6 is calculated and calculated in Qp = Q0 + α (Ttan−Ttanst) and the electronic control unit 4. The necessary minimum flow rate Q0 and the operation constant α are as described above in step S106.
In the fourth embodiment, as in the second embodiment, even if the pump inlet temperature sensor 31 fails, the necessity of increasing the flow rate of the electric low-pressure pump 6 can be determined based on the tank temperature. In contrast, the fuel temperature control with higher reliability is performed.

  The present invention can be applied to a common rail fuel injection control apparatus in which reliable suppression and prevention of an unnecessary temperature rise of fuel supplied to a high pressure pump is desired.

4 ... Electronic control unit 31 ... Pump inlet temperature sensor 32 ... Pump outlet temperature sensor 33 ... Filter temperature sensor 34 ... Tank temperature sensor

Claims (6)

The fuel in the fuel tank is pressurized and pumped to the common rail by the high-pressure pump, and high-pressure fuel can be injected into the engine via the fuel injection valve connected to the common rail, and surplus fuel in the common rail is supplied to the high-pressure pump. A fuel temperature suppression control method in a common rail fuel injection control device configured to be capable of being discharged between the fuel tank and the high-pressure pump via a pressure control valve provided on the downstream side,
When the inlet temperature of the high-pressure pump exceeds the inlet control reference temperature, the discharge flow rate of the electric low-pressure pump that sends the fuel in the fuel tank to the high-pressure pump is set to the inlet temperature of the high-pressure pump and the inlet control reference. While increasing according to the difference with temperature ,
When the inlet temperature of the high-pressure pump does not exceed the inlet control reference temperature, and the outlet temperature of the high-pressure pump exceeds the outlet control reference temperature, the discharge flow rate of the electric low-pressure pump is A fuel temperature suppression control method, wherein the temperature is increased according to a difference between an outlet temperature of a high-pressure pump and the outlet control reference temperature . The fuel in the fuel tank is pressurized and pumped to the common rail by the high-pressure pump, and high-pressure fuel can be injected into the engine via the fuel injection valve connected to the common rail, and surplus fuel in the common rail is supplied to the high-pressure pump. A fuel temperature suppression control method in a common rail fuel injection control device configured to be capable of being discharged between the fuel tank and the high-pressure pump via a pressure control valve provided on the downstream side,
When the inlet temperature of the high-pressure pump exceeds the inlet control reference temperature, the discharge flow rate of the electric low-pressure pump that sends the fuel in the fuel tank to the high-pressure pump is set to the inlet temperature of the high-pressure pump and the inlet control reference. While increasing according to the difference with temperature,
When the inlet temperature of the high pressure pump does not exceed the inlet control reference temperature, the filter temperature, which is the temperature of the filter provided between the high pressure pump and the fuel tank, exceeds the filter control reference temperature. A fuel temperature suppression control method , wherein the discharge flow rate of the electric low-pressure pump is increased in accordance with a difference between the filter temperature and the filter control reference temperature . The fuel in the fuel tank is pressurized and pumped to the common rail by the high-pressure pump, and high-pressure fuel can be injected into the engine via the fuel injection valve connected to the common rail, and surplus fuel in the common rail is supplied to the high-pressure pump. A fuel temperature suppression control method in a common rail fuel injection control device configured to be capable of being discharged between the fuel tank and the high-pressure pump via a pressure control valve provided on the downstream side,
When the inlet temperature of the high-pressure pump exceeds the inlet control reference temperature, the discharge flow rate of the electric low-pressure pump that sends the fuel in the fuel tank to the high-pressure pump is set to the inlet temperature of the high-pressure pump and the inlet control reference. While increasing according to the difference with temperature,
When the inlet temperature of the high-pressure pump does not exceed the inlet control reference temperature and the temperature of the fuel tank exceeds the tank control reference temperature, the discharge flow rate of the electric low-pressure pump is set to the fuel A fuel temperature suppression control method , wherein the temperature is increased according to a difference between a tank temperature and the tank control reference temperature . The fuel in the fuel tank is pressurized and pumped to the common rail by the high-pressure pump, and high-pressure fuel can be injected into the engine via the fuel injection valve connected to the common rail, and surplus fuel in the common rail is supplied to the high-pressure pump. A common rail fuel that is configured to be capable of being discharged between the fuel tank and the high-pressure pump via a pressure control valve provided on the downstream side, and is provided with an electronic control unit that enables drive control of the pressure control valve. An injection control device,
The electronic control unit is
When it is determined that the inlet temperature of the high-pressure pump exceeds the inlet control reference temperature, the discharge flow rate of the electric low-pressure pump that sends the fuel in the fuel tank to the high-pressure pump is set as the inlet temperature of the high-pressure pump. While increasing according to the difference from the inlet control reference temperature,
When it is determined that the inlet temperature of the high pressure pump does not exceed the inlet control reference temperature and the outlet temperature of the high pressure pump is determined to exceed the outlet control reference temperature, the electric low pressure pump A common rail fuel injection control apparatus , wherein the discharge flow rate is configured to increase in accordance with a difference between an outlet temperature of the high-pressure pump and the outlet control reference temperature . The fuel in the fuel tank is pressurized and pumped to the common rail by the high-pressure pump, and high-pressure fuel can be injected into the engine via the fuel injection valve connected to the common rail, and surplus fuel in the common rail is supplied to the high-pressure pump. A common rail fuel that is configured to be capable of being discharged between the fuel tank and the high-pressure pump via a pressure control valve provided on the downstream side, and is provided with an electronic control unit that enables drive control of the pressure control valve. An injection control device,
The electronic control unit is
When it is determined that the inlet temperature of the high-pressure pump exceeds the inlet control reference temperature, the discharge flow rate of the electric low-pressure pump that sends the fuel in the fuel tank to the high-pressure pump is set as the inlet temperature of the high-pressure pump. While increasing according to the difference from the inlet control reference temperature,
It is determined that the inlet temperature of the high-pressure pump does not exceed the inlet control reference temperature, and the filter temperature, which is the temperature of the filter provided between the high-pressure pump and the fuel tank, exceeds the filter control reference temperature. The common rail fuel injection control is configured to increase the discharge flow rate of the electric low-pressure pump according to the difference between the filter temperature and the filter control reference temperature when it is determined that apparatus. The fuel in the fuel tank is pressurized and pumped to the common rail by the high-pressure pump, and high-pressure fuel can be injected into the engine via the fuel injection valve connected to the common rail, and surplus fuel in the common rail is supplied to the high-pressure pump. A common rail fuel that is configured to be capable of being discharged between the fuel tank and the high-pressure pump via a pressure control valve provided on the downstream side, and is provided with an electronic control unit that enables drive control of the pressure control valve. An injection control device,
The electronic control unit is
When it is determined that the inlet temperature of the high-pressure pump exceeds the inlet control reference temperature, the discharge flow rate of the electric low-pressure pump that sends the fuel in the fuel tank to the high-pressure pump is set as the inlet temperature of the high-pressure pump. While increasing according to the difference from the inlet control reference temperature,
When it is determined that the inlet temperature of the high-pressure pump does not exceed the inlet control reference temperature and it is determined that the temperature of the fuel tank exceeds the tank control reference temperature, the discharge of the electric low-pressure pump A common rail fuel injection control device , wherein the flow rate is increased in accordance with a difference between the temperature of the fuel tank and the tank control reference temperature .

Images