JP3323600B2 - Fuel temperature detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel temperature detecting device for detecting the temperature of fuel stored in a fuel tank.

[0002]

2. Description of the Related Art Conventionally, as shown in, for example, Japanese Patent Application Laid-Open No. 4-292565, a temperature measuring means for measuring the temperature in a fuel tank at regular intervals, and calculating the amount of fuel evaporation from the measured temperature. 2. Description of the Related Art There is known an evaporative fuel processing apparatus that includes an evaporative amount calculator, an integrating device that integrates the amount of fuel evaporation calculated by the evaporative amount calculator, and a canister that adsorbs the evaporative fuel. Then, when it is confirmed that the fuel evaporation amount integrated by the integrating means exceeds the limit adsorption amount of the canister, the evaporated fuel generated in the fuel tank is sent to the oxidation catalyst by a pump, and the oxidation catalyst is heated by the heater. And the above-mentioned fuel is burned by overheating.

[0003]

As described above, in the evaporative fuel processing apparatus configured to execute the combustion control of the evaporative fuel corresponding to the temperature in the fuel tank, the fuel generated by the change in the temperature in the fuel tank. Has the advantage that the above-described combustion control can be properly executed by accurately detecting a change in the amount of evaporation of the fuel tank, but it is necessary to newly provide a temperature measurement detection circuit having a temperature sensor for detecting the temperature in the fuel tank. Therefore, there is a problem that the structure of the device becomes complicated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and accurately detects the fuel temperature in a fuel tank with a simple configuration without newly installing a temperature detecting circuit. It is an object of the present invention to provide a fuel temperature detecting device capable of detecting a fuel temperature.

[0005]

The invention according to claim 1 is
A thermistor-type fuel level sensor for detecting the level of fuel contained in the fuel tank, a current sensor for detecting a current value flowing through the fuel level sensor, and a fuel temperature based on the current value detected by the current sensor. And a temperature measuring means for measuring.

According to a second aspect of the present invention, in the fuel temperature detecting device according to the first aspect of the present invention, it has been confirmed that the fuel level has dropped below a region where the fuel level sensor can detect the fuel level. In this case, a prohibition means for prohibiting the measurement of the fuel temperature by the temperature measurement means is provided.

According to a third aspect of the present invention, in the fuel temperature detecting device according to the second aspect, when it is confirmed that the current flowing through the fuel level sensor has become equal to or higher than a predetermined reference value, The fuel level is determined to have fallen below the range in which the fuel temperature can be detected, and the measurement of the fuel temperature by the temperature measuring means is prohibited by the prohibiting means.

According to a fourth aspect of the present invention, in the fuel temperature detecting device according to the second aspect, when the prohibiting means for prohibiting the measurement of the fuel temperature by the temperature measuring means is operated, the fuel temperature before the prohibiting means is operated is measured. It is configured to set the measured value as the fuel temperature.

According to a fifth aspect of the present invention, in the fuel temperature detecting device according to the first aspect of the present invention, the vaporized fuel generated in the fuel tank is purged and burned according to the fuel temperature measured by the temperature measuring means. A correction means for correcting the purge amount of the fuel vapor in the fuel vapor combustion processing device is provided.

[0010]

According to the first aspect of the present invention, when the temperature of the fuel contained in the fuel tank rises and the electric resistance of the thermistor type fuel level sensor decreases, the current flowing through the fuel level sensor accordingly. Since the value increases, the fuel temperature is measured by the temperature measuring means based on the current value.

According to the second aspect of the present invention, when the fuel level is reduced and the cooling function of the fuel level sensor by the fuel is impaired, the measurement of the fuel temperature by the temperature measuring means is prohibited. As a result, erroneous detection of the fuel temperature due to the self-heating of the fuel level sensor is prevented.

According to the third aspect of the present invention, the temperature of the fuel level sensor becomes high due to the decrease of the fuel level,
When the value of the current flowing through the fuel level sensor rises, it is determined that the fuel level has dropped, and the measurement of the fuel temperature by the temperature measuring means is prohibited.
The erroneous detection of the fuel temperature resulting from the self-heating of the fuel level sensor is prevented.

According to the fourth aspect of the present invention, when the fuel level is lowered and the fuel temperature cannot be measured by the temperature measuring means, the fuel temperature is determined based on the previous measured value. Is set, various controls by the control device using the fuel temperature detection device are continuously performed.

According to the fifth aspect of the present invention, the concentration of the fuel vapor generated in the fuel tank is calculated according to the fuel temperature measured by the fuel measuring means. Correction such as reducing the opening of the purge valve of the apparatus is performed.

[0015]

FIG. 1 shows a combustion control system for an engine having a fuel temperature detecting device according to an embodiment of the present invention.
The combustion control system includes a fuel supply pipe 3 for supplying fuel contained in a fuel tank 1 to an engine main body 2, an intake passage 4 for supplying intake air to the engine main body 2, and a combustion chamber of the engine main body 2. It has an exhaust passage 5 for discharging the generated exhaust gas to the outside, and an evaporative fuel combustion processing device 6 for purging the evaporative fuel generated in the fuel tank 1 to process the fuel.

The fuel supply pipe 3 is provided with a fuel injection pump 7 for sucking and injecting the fuel in the fuel tank 1 and a fuel for injecting the fuel derived from the fuel injection pump 7 into a combustion chamber of the engine body 1. An injection nozzle 8 is provided.
The intake passage 4 is provided with a throttle valve 9 for adjusting an intake air amount and a surge tank 10 for suppressing pulsation of the intake air.

The combustion processing apparatus 6 includes a discharge pipe 11 from which the fuel vapor generated in the fuel tank 1 is discharged, and a canister 12 provided with activated carbon for adsorbing the fuel vapor discharged into the discharge pipe 11. The fuel vapor adsorbed by the canister 12 is supplied to the surge tank 1 of the intake passage 4.
And a supply pipe 13 for supplying the gas to the inside. The supply pipe 13 is provided with a purge valve 15 composed of an open / close valve. When it is confirmed that the purge condition is satisfied in accordance with the operation state of the engine, the purge valve 15 outputs a control signal output from the control unit 14. , The fuel vapor adsorbed by the canister 12 is supplied into the surge tank 10 through the supply pipe 13.

A thermistor type fuel level sensor 16 is installed near the bottom of the fuel tank 1. A power supply line 18 for supplying electric power from a battery 17 to the fuel level sensor 16 is provided with a remaining amount warning light 19, A current sensor 20 for detecting the amount is provided. When a sufficient amount of fuel is contained in the fuel tank 1, the fuel cools the thermistor type fuel level sensor 15 and the resistance thereof becomes a large value. As a result, the remaining amount warning lamp 19 is not lit.

Then, the residual fuel in the fuel tank 1 is reduced, and the cooling effect of the fuel on the fuel level sensor 16 by this fuel is reduced.
When the electric current supplied to the fuel level sensor 16 increases, the electric current supplied to the fuel level sensor 16 increases because the fuel level sensor 16 generates heat by itself and its electric resistance decreases. The warning light 19 is turned on.

When it is confirmed that the purge condition is satisfied in accordance with the operation state of the engine detected by the temperature of the cooling water of the engine, the opening of the throttle valve, and the like, the control unit 14 controls the intake air. A purge control means 21 is provided for calculating a basic purge amount of the evaporated fuel stored in the canister 12 according to the amount and the like, and outputting a control signal corresponding thereto.

The control unit 14 has a temperature measuring means 22 for measuring the temperature of the fuel in the fuel tank 1 in accordance with the detection signal output from the current sensor 20, and the temperature measured by the temperature measuring means 22. Depending on the fuel temperature,
It has been confirmed that the fuel level has fallen below the region where the fuel level can be detected by the correcting means 23 for correcting the basic purge amount of the evaporated fuel set in the purge control means 21 and the fuel level sensor 16. In this case, a prohibition unit 24 for prohibiting the temperature measurement unit 22 from measuring the fuel temperature is provided.

The temperature measuring means 22 detects the fuel temperature based on a current value supplied to the thermistor-type fuel level sensor 16 which changes in response to a change in the temperature of the fuel contained in the fuel tank 1. It is configured as follows.
That is, as shown in FIG. 2, as the fuel temperature in the fuel tank 1 increases, the electric resistance value of the fuel level sensor 16 decreases, and the current value of the energizing line 18 increases correspondingly. Therefore, the fuel temperature is measured by the temperature measuring means 22 according to the current value.

The correcting means 23 is adapted to operate the canister 12 in accordance with the fuel temperature measured by the temperature measuring means 22.
And the like. If the concentration is high, the basic purge amount set by the purge control means 21 is increased, and if the concentration of the evaporative fuel is low, the basic purge amount is increased. By reducing the amount, the purge amount of the evaporated fuel supplied from the purge valve 15 to the engine body 2 is corrected.

The prohibiting means 24 is connected to the current sensor 20.
When the current value detected by the sensor becomes equal to or higher than a predetermined reference value, the fuel level is changed to the fuel level sensor 1.
6, it is determined that the current value has increased because the cooling function of the fuel level sensor 16 cannot be obtained by the fuel because the fuel level has decreased below the region where the fuel level can be detected. It is configured to prohibit. When the prohibiting means 24 is operated, a measured value of the fuel temperature before the prohibiting means 24 is operated is set as the fuel temperature in the temperature measuring means 22,
The correction of the purge amount is performed according to the fuel temperature.

The operation of measuring the fuel temperature in the control unit 14 will be described with reference to the flowchart shown in FIG. First, in step S1, the detection value i of the current sensor 20 is read, and then in step S2, it is determined whether the detection value i is smaller than a preset reference value α. The reference value α is set, for example, to a current value at which the remaining amount warning lamp 19 can be turned on.

If the determination in step S2 is YES and it is confirmed that the detected value i is smaller than the preset reference value α, then in step S3 the fuel corresponding to the detected value i is determined. The temperature measured by the temperature means 22 is set as the fuel temperature. In addition, the above step S
If NO is determined in step 2, the measurement of the temperature by the fuel temperature means 22 is prohibited in step S4,
A measured value of the temperature immediately before the detected value i becomes smaller than the reference value is set as the fuel temperature.

Next, the control of the combustion processing of the evaporated fuel executed based on the measured value of the temperature is executed based on the flowchart shown in FIG. First, in step S11,
After inputting each detection signal indicating the operation state of the engine, in step S12, it is determined whether or not the purge condition is satisfied according to the engine temperature or the engine load. If the result of this determination is NO, step S1
In 3, the purge amount of the evaporated fuel is set to 0, and the purge valve 15 is closed.

If the determination in step S12 is YES,
If it is confirmed that the purge condition is satisfied, in step S14, a basic purge amount of the evaporated fuel corresponding to the operating state of the engine is set according to the engine speed and the engine load. Next, in step S15, the correction amount of the purge amount is set based on the measured value of the fuel temperature. Then, in step S16, after setting the final purge amount based on the basic purge amount and the correction amount, in step S17, the opening degree of the purge valve 15 corresponding to the final purge amount is set.
The control signal corresponding to this is output and the control is terminated.

As described above, the current value i of the thermistor type fuel level sensor 16 installed in the fuel tank 1 is detected by the current sensor 20, and the fuel stored in the fuel tank 1 according to the current value i is detected. Since the temperature is configured to be measured, the fuel temperature can be detected without newly providing a temperature measurement detection circuit having a temperature sensor or the like. Therefore, the change in the concentration of the evaporated fuel contained in the canister 12 or the like is accurately detected in accordance with the measured value of the fuel temperature, and the purge amount of the evaporated fuel corresponds to the change in the concentration during the combustion processing of the evaporated fuel. By performing the correction in this way, the above-described combustion processing can be properly performed.

In the above embodiment, when it is confirmed that the current value i detected by the current sensor 20 is larger than the preset reference value α, the fuel level in the fuel tank 1 is changed to the fuel level. Since the sensor 16 is configured to determine that the fuel level has fallen below the range where the fuel level can be detected, and the measurement of the fuel temperature by the temperature measuring means 22 is prohibited, the fuel level is reduced and the fuel level by the fuel is reduced. In the state where the cooling function of the sensor 16 is impaired, it is possible to prevent the fuel temperature from being erroneously detected due to the measurement of the fuel temperature.

It is to be noted that, instead of the above-described configuration in which the decrease in the fuel level is detected based on the detection value of the current sensor 20,
It is configured to determine whether or not the fuel level is lower than that of the installation part of the thermistor type fuel level sensor 16 based on a detection value of a fuel level detection means such as a float type provided separately. Is also good.

Further, as described above, the fuel level sensor 16
The prohibiting means 24 prohibits the measurement of the fuel temperature when the current value increases due to the fact that the fuel level is lower than that of the installation part and the cooling action of the fuel level sensor 16 by the fuel cannot be obtained. In addition, according to the configuration in which the measured value before the operation of the prohibition unit 24 is set as the fuel temperature, the control of the combustion processing apparatus 5 can be performed without stopping the operation of correcting the purge amount by the correction unit 23. Can continue.

The fuel temperature detection device according to the present invention
The control is not limited to the correction of the purge amount by the combustion processing apparatus 5, but various controls that change according to the fuel temperature, for example, when bubbles are generated due to an increase in the fuel temperature, the fuel supply amount is reduced. It can also be used for controlling the amount of fuel supplied to prevent such a situation.

[0034]

As described above, according to the present invention, the current value of the thermistor type fuel level sensor installed in the fuel tank is detected by the current sensor, and the current value is stored in the fuel tank in accordance with the current value. Since the fuel temperature is configured to be measured, the fuel temperature can be detected with a simple configuration without newly providing a temperature detection circuit having a temperature sensor or the like.

When it is confirmed that the fuel level in the fuel tank has fallen below the range where the fuel level can be detected by the fuel level sensor, the measurement of the fuel temperature by the temperature measuring means is prohibited. With this configuration, it is possible to prevent the fuel temperature from being erroneously detected due to the measurement of the fuel temperature in a state where the fuel level is reduced and the cooling function of the fuel level sensor by the fuel is impaired. The temperature of the fuel stored in the fuel tank can be properly measured.

When it is confirmed that the current value detected by the current sensor is larger than a predetermined reference value, the fuel level in the fuel tank may be detected by the fuel level sensor. According to the configuration in which the fuel level is determined to be lower than the allowable range and the measurement of the fuel temperature by the temperature measuring means is prohibited, the erroneous detection of the fuel temperature caused by the lowering of the fuel level with a simple configuration is achieved. Can be prevented from being performed.

Further, when the fuel level is reduced and the fuel temperature cannot be measured by the temperature measuring means, the fuel temperature is set based on the previous measured value. Is advantageous in that various controls by the control device using the fuel temperature detection device can be continuously executed without stopping.

In the case where a correction means for correcting the purge amount of the evaporated fuel in the combustion processing apparatus for the evaporated fuel generated in the fuel tank is provided according to the fuel temperature measured by the temperature measuring means, According to the fuel temperature measured by the measuring means, the concentration change of the evaporated fuel is accurately detected in accordance with the measured value of the fuel temperature, and during the combustion processing of the evaporated fuel, the purge amount of the evaporated fuel is determined by the concentration change. Thus, the above-described fuel vapor can be properly subjected to combustion processing.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory diagram of an engine combustion control system having a fuel temperature detecting device according to an embodiment of the present invention.

FIG. 2 is a graph showing a relationship between an electric resistance value and a current value of a thermistor type fuel level sensor and a fuel temperature.

FIG. 3 is a flowchart showing an operation state of the fuel temperature detection device.

FIG. 4 is a flowchart illustrating combustion processing control of evaporated fuel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel tank 6 Combustion processing apparatus 16 Fuel level sensor 20 Current sensor 22 Temperature measurement means 23 Correction means 24 Prohibition means

Claims (5)

(57) [Claims] 1. A thermistor-type fuel level sensor for detecting the level of fuel contained in a fuel tank, a current sensor for detecting a current value flowing through the fuel level sensor,
And a temperature measuring means for measuring a fuel temperature based on a current value detected by the current sensor. 2. A prohibition means for prohibiting measurement of the fuel temperature by the temperature measurement means when it is confirmed that the fuel level has fallen below the range where the fuel level can be detected by the fuel level sensor. The fuel temperature detecting device according to claim 1, wherein: 3. When it is confirmed that the value of the current flowing through the fuel level sensor is equal to or higher than a predetermined reference value, it is determined that the fuel level has fallen below the fuel level detectable region. 3. The fuel temperature detecting device according to claim 2, wherein the measurement of the fuel temperature by the temperature measuring means is prohibited by the prohibiting means. 4. When the prohibiting means for prohibiting the measurement of the fuel temperature by the temperature measuring means is operated, a measured value of the fuel temperature before the operation of the prohibiting means is set as the fuel temperature. Item 3. The fuel temperature detecting device according to Item 2. 5. A correcting means for correcting a purge amount of an evaporated fuel in an evaporative fuel combustion processing apparatus for purging an evaporative fuel generated in a fuel tank and performing a combustion process in accordance with the fuel temperature measured by the temperature measuring means. The fuel temperature detecting device according to claim 1, wherein the fuel temperature detecting device is provided.