JPH0861175A - Fuel pump control device - Google Patents

Abstract

PURPOSE: To improve engine startability when a fuel temperature is high by raising fuel pressure by actuation of a fuel pump before an engine is started after an ignition switch is turned on. CONSTITUTION: After an ignition switch 22a is turned on, whether or not a cooling water temperature THW of an engine 11 is not less than α is judged, and when THW>=α is realized, whether or not an intake air temperature THA is not less than β is judged. If THA>=β is realized, since it is estimated that a fuel temperature in a fuel tank 24 is put in a high temperature area and it is thought that vapor is generated in a fuel filter 27, the actuating time TP of a fuel pump 25 is set in the time by adding the time TF necessary to discharge vapor to the ordinary time TC. In a case except this, it is estimated that the fuel temperature is put in a normal temperature low temperature area, and since generation of the vapor does not become a problem, the actuating time TP of the fuel pump is set only in the ordinary time TC. Afterward, the fuel pump is actuated, and when a starter switch 22b is not turned on, the fuel pump is continuously actuated until the actuating time becomes TP.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel pump controller for operating a fuel pump immediately after turning on an ignition switch and before starting an engine to increase fuel pressure.

[0002]

2. Description of the Related Art Conventionally, a fuel pump control device of this type has been
As shown in Japanese Patent Laid-Open No. 57-203826, the fuel pump is operated for a certain period of time immediately after the ignition switch is turned on, and the operation of the fuel injection valve is prohibited during the operation of the fuel pump. With this configuration,
The fuel pressure in the fuel pipe, which has dropped when the engine is stopped for a long time, is quickly increased to restore the engine startability.

[0003]

By the way, as a cause of deterioration of engine startability, in addition to the above-mentioned decrease in fuel pressure in the fuel pipe during engine stop, in the fuel filter provided on the suction port side of the fuel pump. There is the presence of vapor (air bubbles) generated in. This vapor is generated when the fuel pump is stopped after the engine is stopped and suction pressure is no longer applied to the fuel filter, and the generated amount tends to increase as the fuel temperature in the fuel tank increases.
Also, the temperature of the fuel in the fuel tank rises as part of the fuel is returned from the fuel injection valve to the inside of the fuel tank through the fuel pressure regulating valve while the engine is operating. As a result, the fuel temperature in the fuel tank also rises, and vapor is likely to be generated in the fuel filter. In this state, when the engine is subsequently started, the fuel pump sucks the vapor and the rise of the fuel pressure tends to be delayed.

However, the one described in the above-mentioned publication does not consider the problem of delay in rising of the fuel pressure due to the generation of vapor in the fuel filter at all, and in particular,
When the fuel temperature in the fuel tank becomes high and the amount of vapor generated in the fuel filter becomes large, there is a problem that the fuel pressure is not increased before starting the engine and the engine startability is deteriorated.

The present invention has been made in view of the above circumstances, and therefore an object thereof is to increase the fuel pressure before starting the engine in consideration of the delay in rising of the fuel pressure due to the generation of vapor in the fuel filter. (EN) A fuel pump control device capable of increasing the fuel pressure even when the fuel temperature in the fuel tank is high and improving the engine startability.

[0006]

In order to achieve the above object, a fuel pump control device according to claim 1 of the present invention comprises a fuel temperature information detecting means for detecting information on the temperature of fuel in a fuel tank, and an ignition. A first determining means for determining whether the switch is on or off; a second determining means for determining whether or not the engine has not been started; and, after the ignition switch is turned on, the fuel temperature is in a normal temperature region or a low temperature region and Control means for operating the fuel pump for a predetermined time when it is determined that the engine has not been started, and for operating the fuel pump for a time longer than the predetermined time when it is determined that the fuel temperature is in a high temperature region and before the engine has started. It has been configured.

In this case, as in claim 2, the fuel temperature information detecting means is provided by either or both of the cooling water temperature detecting means for detecting the engine cooling water temperature and the intake air temperature detecting means for detecting the intake air temperature. The information may be used as the information about the fuel temperature.

Alternatively, as in claim 3, the fuel temperature information detecting means may use the information from the electric fan operating state detecting means for detecting the operating state of the radiator electric fan as the information on the fuel temperature. .

Further, according to a fourth aspect of the invention, the control means sets the operating time of the fuel pump to be operated when the fuel temperature is in a high temperature region and before it is determined that the engine has been started to be longer as the fuel temperature becomes higher. You may configure so that it may be set.

[0010]

According to the above-described fuel pump control apparatus of the present invention, when the first determining means determines that the ignition switch is turned on, the information about the fuel temperature in the fuel tank is detected by the fuel temperature information detecting means. Then, it is determined whether the fuel temperature is in the high temperature region or in the normal temperature region / low temperature region, and it is determined by the second determining means whether or not the engine has been started. As a result, when it is determined that the fuel temperature is in the normal temperature range or the low temperature range and before the engine is started, the control means operates the fuel pump for a predetermined time, but when it is determined that the fuel temperature is in the high temperature range and before the engine is started. , Operate the fuel pump for a time longer than a predetermined time. As a result, the fuel pressure is sufficiently increased even when the fuel temperature is high.

In this case, the fuel temperature information detecting means may be provided with a temperature sensor in the fuel tank to directly measure the fuel temperature, but as in claim 2, cooling for detecting the engine cooling water temperature. Information from both or one of the water temperature detecting means and the intake air temperature detecting means for detecting the intake air temperature may be used as the information regarding the fuel temperature. That is, the engine cooling water temperature detected by the cooling water temperature detecting means reflects the temperature state of the engine, and when the engine is in a high temperature state, the fuel temperature in the fuel tank also rises due to the influence of the engine cooling water temperature. Can be used as Further, since the intake air temperature detected by the intake air temperature detecting means is related to both the outside air temperature and the engine temperature, and the fuel temperature also changes depending on the outside air temperature, the intake air temperature can also be used as information about the fuel temperature.

Further, as in claim 3, the fuel temperature information detecting means may use the information from the electric fan operating state detecting means for detecting the operating state of the radiator electric fan as the information on the fuel temperature. In other words, since the operating state of the radiator electric fan can be switched according to the engine cooling water temperature (radiator temperature), it is possible to estimate the engine cooling water temperature by detecting the operating state of the radiator electric fan. As described above, the cooling water temperature can be used as the information on the fuel temperature.

According to the third aspect of the present invention, the fuel pump can be operated while the radiator electric fan is operating when the fuel temperature is in the high temperature range, so that the fuel pump that is not heard by the passenger during normal operation is provided. It is possible to make the operating noise of (3) inconspicuous by the operating noise of the radiator electric fan that passengers are accustomed to hearing.

Further, in the present invention, the control means sets the operating time of the fuel pump to be operated when the fuel temperature is in the high temperature range and before it is determined that the engine is started to be longer as the fuel temperature becomes higher. Set. As a result, the operating time of the fuel pump is finely adjusted according to the fuel temperature, the pressure of the fuel is raised without excess and deficiency, and the operating time of the fuel pump is suppressed to the necessary minimum.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. First, a schematic configuration of the entire engine control system will be described based on FIG. In the engine 11,
A water temperature sensor 12 (engine cooling water temperature detecting means) for detecting the engine cooling water temperature and an electromagnetic pickup type rotation sensor 15 for detecting the rotation of the detection gear 14 fitted to the crankshaft 13 are provided. On the other hand, an air cleaner 18 is mounted on the upstream side of an intake pipe 17 connected to the intake port side of the engine 11, and the temperature (intake air temperature) of engine intake air passing through the air cleaner 18 is measured by an intake air temperature sensor 19
(Intake air temperature detecting means). Further, an intake air amount sensor 20 that detects an intake air amount is provided downstream of the air cleaner 18.

A radiator electric fan 21 is provided to cool a radiator (not shown) that radiates engine cooling water. The key switch 22 is
The ignition switch 22a and the starter switch 22b for starting the engine 11 are provided, and when the key 23 is inserted into the key switch 22 and is rotated, the ignition switch 22a and the starter switch 22b are sequentially turned on.

On the other hand, a fuel pump 25 is provided in a fuel tank 24 for storing fuel (gasoline), and a fuel filter 27 is attached to an inlet portion of a suction pipe 26 of the fuel pump 25. The fuel pipe 28 connected to the discharge port side of the fuel pump 25 is connected to a fuel injection valve 29 attached to the intake pipe 17. The fuel pressure in the fuel pipe 28 is kept constant by the fuel pressure regulating valve 30. The fuel pressure regulating valve 30 communicates with the inside of the fuel tank 24 through the fuel return pipe 31 so that a part of the fuel is returned from the fuel injection valve 29 through the fuel pressure regulating valve 30 into the fuel tank 24 while the engine 11 is operating. It has become.

The above-mentioned fuel pump 25 and fuel injection valve 29
Also, the radiator electric fan 21 is connected to the electronic control unit 3
2 (hereinafter referred to as "ECU 32").
The ECU 32 is mainly composed of a microcomputer, calculates the fuel injection amount based on various signals from the water temperature sensor 12, the rotation sensor 15, the intake air temperature sensor 19, and the intake air amount sensor 20, and injects the fuel at every constant crank angle. A signal is output to the fuel injection valve 29 to inject fuel into the intake pipe 17. This fuel injection signal is repeatedly output until the rotation sensor 15 detects that the crankshaft 13 has stopped rotating.

Further, the ECU 32 executes the control program shown in FIG. 1 to detect the output information of the water temperature sensor 12 and the intake air temperature sensor 19 as information on the temperature of the fuel in the fuel tank 24. Ignition switch 2
It functions as a "first determination means" for determining whether the 2a is turned on or off, and further determines whether or not the engine 11 has been started based on the on / off signal of the starter switch 22b. After the ignition switch 22a is turned on, the fuel pump 25 is operated for a predetermined time Tc when it is determined that the fuel temperature is in the normal temperature range or the low temperature range and before the engine 11 is started, and the fuel temperature is in the high temperature range. In addition, when it is determined that the engine has not been started, it also functions as "control means" that operates the fuel pump 25 for a time longer than a predetermined time (TC + TF).

Hereinafter, the fuel pump 2 by the ECU 32 will be described.
The control contents of 5 will be described in detail with reference to the flowchart of FIG. First, in step S1, it is determined whether or not the ignition switch 22a is turned on. If not, the process waits until it is turned on. After that, when the ignition switch 22a is turned on, step S
The routine proceeds to step 2 to determine whether the engine cooling water temperature THW detected by the water temperature sensor 12 is α or higher. Where α
Is set to a temperature slightly higher than 100 ° C. as shown in FIG. 3, and when the engine cooling water temperature THW becomes α or higher, the fuel temperature in the fuel tank 24 enters a high temperature region (for example, 40 ° C. or higher). there is a possibility. This is because some fuel is returned from the fuel injection valve 29 into the fuel tank 24 through the fuel pressure regulating valve 30 during operation of the engine 11, so that the engine 11 is in a high temperature state (that is, the engine cooling water temperature THW is in a high temperature state). This is because sometimes the temperature of the fuel in the fuel tank 24 also rises due to the influence.

If the determination in step S2 is "No", that is, if the engine cooling water temperature THW is lower than α, it is estimated that the fuel temperature in the fuel tank 24 is in the normal temperature region or the low temperature region, Since the generation of vapor in the fuel filter 27 does not pose a problem, the process proceeds to step S4 and the operating time TP of the fuel pump 25 is set to a predetermined constant time TC. This time T C is the time required for the fuel pipe 28 when no vapor is generated in the fuel filter 27.
This is the operating time of the fuel pump 25 required to increase the internal fuel pressure.

On the other hand, if the determination in step S2 is "Yes", that is, if the engine cooling water temperature THW is α or above, the routine proceeds to step S3, where the intake air temperature THA detected by the intake air temperature sensor 19 is β or above. Determine if there is.
Here, β is set to a temperature slightly lower than 100 ° C. as shown in FIG. 3, and when the intake air temperature THA becomes β or more, it is estimated that the fuel temperature in the fuel tank 24 is in the high temperature region. . The reason is that the intake air temperature THA is related to both the outside air temperature and the temperature of the engine 11 (engine cooling water temperature THW),
Since the fuel temperature also changes depending on the outside air temperature, the intake temperature THA as well as the engine cooling water temperature THW is used as the information regarding the fuel temperature to improve the accuracy of detecting the fuel temperature.

If the determination in step S3 is "No", that is, if the intake air temperature THA is lower than β, it is estimated that the fuel temperature in the fuel tank 24 is in the normal temperature region or the low temperature region. Similarly to the case of THW <α described above, the process proceeds to step S4, and the operating time TP of the fuel pump 25 is set to a predetermined constant time TC. On the other hand, if the determination in step S3 is “Yes”, that is,
If the intake air temperature THA is β or more, the routine proceeds to step S5, where the operating time TP of the fuel pump 25 is set to TC + TF (that is, a time longer than the predetermined time TC by TF). Here, the time TF is the operating time of the fuel pump 25 (hereinafter referred to as “vapor discharge time”) required to discharge the vapor generated in the fuel filter 27 when the fuel temperature is in the high temperature region. In the first embodiment,
The vapor discharge time TF is a fixed time.

The relationship between the vapor discharge time TF and the fuel filter 27 changes depending on the shape of the fuel filter 27 and the performance of the fuel pump 25, and the amount of vapor in the fuel filter 27 and the fuel in the fuel tank 24. The relationship with temperature is
It changes depending on the fuel property and the shape of the fuel filter 27. Therefore, the vapor discharge time TF may be appropriately determined in consideration of the shape of the fuel filter 27 of the vehicle type to which the present invention is applied, the performance of the fuel pump 25, and the fuel property.

After the operating time TP of the fuel pump 25 is obtained in step S4 or S5 as described above, step S4
6, the fuel pump 25 is operated, and its operation time T
P is decremented (step S7), and it is determined whether the starter switch 22b is turned on, that is, the engine 11 is started. If starter switch 2
When 2b is turned on, this control program is terminated and the normal engine control program is restored.

On the other hand, if the starter switch 22b is off, that is, before the engine 11 is started, step S
If No. 8 is "No", the process proceeds to step S9 to determine whether the operating time TP of the fuel pump 25 has become "0".
That is, it is determined whether the operating time of the fuel pump 25 has elapsed by the time TP obtained in step S4 or step S5. The processes of steps S7 to S9 are repeated until "Yes" is determined in this step S9, and if the starter switch 22b is turned on in the middle of the process, the control program is terminated at that point, but otherwise. For example, when the operating time of the fuel pump 25 has passed the time TP obtained in step S4 or step S5, the determination in step S9 becomes "Yes", and the process proceeds to step S10 to stop the fuel pump 25, The control program is terminated and the normal engine control program is restored.

According to the first embodiment described above, when it is determined that the fuel temperature in the fuel tank 24 is in the high temperature region and before the engine 11 is started, the operating time TP of the fuel pump 25 is set to the normal time TC. Than the time required to discharge the vapor TF
Therefore, the fuel pressure can be sufficiently increased not only at the time of starting at normal temperature but also at the time of starting at high temperature, and the startability of the engine 11 can be improved.

Moreover, the engine cooling water temperature THW detected by the water temperature sensor 12 and the intake air temperature THA detected by the intake air temperature sensor 19 are used as information regarding the fuel temperature in the fuel tank 24. Since it is not necessary to provide a temperature sensor for measuring, the cost increase can be suppressed. However, the present invention may be provided with a temperature sensor for measuring the fuel temperature,
Even in this case, it goes without saying that the intended purpose of the present invention can be sufficiently achieved.

In the first embodiment, the water temperature sensor 12
The fuel temperature is detected by using the output information of both the intake air temperature sensor 19 and the intake air temperature sensor 19 to improve the accuracy of the detection of the fuel temperature. However, only the output information of one of the sensors is stored in the fuel tank 24. The intended purpose of the present invention can be achieved even if it is used as information on the fuel temperature.

Alternatively, as in the second embodiment of the present invention shown in FIGS. 4 to 6, the operating state of the radiator electric fan 21 may be used as information regarding the fuel temperature in the fuel tank 24. That is, the radiator electric fan 21
Since the operating state of is switched according to the engine cooling water temperature (radiator temperature) as shown in FIG. 3, it is possible to estimate the engine cooling water temperature by detecting the operating state of the radiator electric fan 21. The engine cooling water temperature can be used as the information about the fuel temperature as described in the first embodiment.

The control flow of the second embodiment is the same as that of the first embodiment.
The steps S2 and S3 in the embodiment are replaced by the step S in FIG.
2a may be replaced, and other processing may be the same as in the first embodiment. That is, when the ignition switch 22a is turned on, the process proceeds to step S2a in FIG. 6 and it is determined whether or not the radiator electric fan 21 is on (operating).
If the radiator electric fan 21 is off (stopped), it is estimated that the fuel temperature in the fuel tank 24 is in the normal temperature region or the low temperature region, as shown in FIG. 3, so the process proceeds to step S4. The operating time TP of the fuel pump 25 is set to a predetermined time TC. on the other hand,
If the radiator electric fan 21 is on (operating),
Since it is estimated that the fuel temperature in the fuel tank 24 is in the high temperature range, the operating time TP of the fuel pump 25 is set to TC +
Set to TF (that is, set to a time longer than the predetermined time TC by TF). Subsequent processing is the same as in the first embodiment described above.

In the second embodiment, in addition to the same effect as the above-described first embodiment, the fuel pump 25 can be operated while the radiator electric fan 21 is operating when the fuel temperature is in the high temperature range. There is also an advantage that the operating noise of the fuel pump 25 that cannot be heard by the occupant during normal operation can be made inconspicuous by the operating noise of the radiator electric fan 21 that the occupant is accustomed to hearing.

In both the first and second embodiments described above, the vapor discharge time TF to be added in the high temperature region is fixed, but it may be varied depending on the fuel temperature. That is, as shown in FIG. 7 (b), the vapor amount increases as the fuel temperature rises, and if the vapor amount increases, the vapor discharge time TF is correspondingly increased as shown in FIG. 7 (a). Need to be long.

From this point of view, in the second embodiment of the present invention shown in FIG. 8, the operating time TP of the fuel pump to be operated when it is determined that the fuel temperature in the fuel tank 24 is in the high temperature region and before the engine is started. Set so that the higher the fuel temperature, the longer the time. Specifically, the processes of steps S3a and S3b of FIG.
es ”or“ Yes ”in step S2a in FIG. First, in step S3a, the fuel tank 24
Determine the fuel temperature inside. The determination of the fuel temperature may be made on the basis of the output information of both the water temperature sensor 12 and the intake air temperature sensor 19 or the output information of either one of them, or the temperature sensor may be provided in the fuel tank 24 to determine the fuel temperature. The temperature may be measured directly.

After determining the fuel temperature in this way, the process proceeds to step S3b, and from the relationship between FIGS. 7 (a) and 7 (b),
Calculate the vapor discharge time TF according to the fuel temperature. At this time, the correspondence relationship between the fuel temperature and the vapor discharge time TF is stored in advance in the ROM (not shown) of the ECU 32 as a map, and the vapor discharge time TF corresponding to the fuel temperature obtained in step S3a is calculated from the map. Ask. Alternatively, the correspondence relationship between the fuel temperature and the vapor discharge time TF is converted into a mathematical expression and EC
The vapor discharge time TF may be calculated by storing it in the ROM (not shown) of U32 and substituting the fuel temperature obtained in step S3a into the mathematical expression. After the vapor discharge time TF is obtained as described above, the operation proceeds to step S5 and the operating time TP of the fuel pump 25 is obtained by adding the vapor discharge time TF to the normal time TC. This step S
The processes after 5 are the same as those in each of the above-described embodiments.

In the third embodiment described above, the operating time T of the fuel pump 25 is changed according to the fuel temperature in the fuel tank 24.
Since P can be finely adjusted, the fuel pressure can be increased without excess or deficiency, and the fuel pump 25
There is also an advantage that the operating time TP can be kept to a necessary minimum and the durability of the fuel pump 25 can be prevented from being unnecessarily impaired.

In each of the above embodiments, the control of FIG. 1 is terminated when the starter switch 22b is turned on during the operating time TP of the fuel pump 25, but the operating time TP of the fuel pump 25 is The starter ON (starting of the engine 11) may be prohibited until the time elapses.

[0038]

As is apparent from the above description, according to the fuel pump control device of the first aspect of the present invention, when it is determined that the fuel temperature in the fuel tank is in the high temperature region and before the engine is started, Since the operation time of the fuel pump is made longer than usual time, not only when starting at normal temperature,
The fuel pressure can be sufficiently increased even at the time of starting at high temperature, and the engine startability can be improved.

Moreover, according to the second aspect, the information from the cooling water temperature detecting means and / or the intake air temperature detecting means is used as the information regarding the fuel temperature. Therefore, the temperature sensor for measuring the fuel temperature in the fuel tank is used. Since it is not necessary to provide, it is possible to suppress cost increase.

Further, according to the third aspect, since the information on the operating state of the radiator electric fan is used as the information on the fuel temperature, the fuel pump is operated during the operation of the radiator electric fan when the fuel temperature is in the high temperature range. The operation sound of the fuel pump that can be operated and cannot be heard by the passenger during normal operation can be made inconspicuous by the operation sound of the radiator electric fan that the passenger is accustomed to hearing.

Further, according to the present invention, the operating time of the fuel pump which is operated when the fuel temperature is in the high temperature region and before it is judged that the engine has been started is set to be longer as the fuel temperature becomes higher. The pressure can be increased without excess and deficiency, and the operating time of the fuel pump can be suppressed to the necessary minimum, which is convenient for maintaining the durability of the fuel pump.

[Brief description of drawings]

FIG. 1 is a flow chart showing a control flow in a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing an entire engine control system.

FIG. 3 is a diagram illustrating a correspondence relationship between a fuel temperature in a fuel tank, a radiator electric fan, an engine cooling water temperature, and an intake air temperature.

FIG. 4 is a time chart showing the flow of control at the time of starting at room temperature in the second embodiment of the present invention.

FIG. 5 is a time chart showing a control flow at the time of starting at a high temperature in the second embodiment of the present invention.

FIG. 6 is a flowchart showing a part of a control flow in the second embodiment of the present invention.

7A is a diagram showing a relationship between a vapor amount and a vapor discharge time TF, and FIG. 7B is a diagram showing a relationship between a fuel temperature and a vapor amount.

FIG. 8 is a flowchart showing a part of a control flow in the third embodiment of the present invention.

[Explanation of symbols]

11 ... Engine, 12 ... Water temperature sensor (cooling water temperature detecting means), 19 ... Intake air temperature sensor (intake air temperature detecting means), 21 ...
Electric radiator fan, 22a ... Ignition switch, 22b ... Starter switch, 24 ... Fuel tank, 2
5 ... Fuel pump, 27 ... Fuel filter, 29 ... Fuel injection valve, 30 ... Fuel pressure regulating valve, 32 ... ECU (control means, fuel temperature information detecting means, first determining means, second determining means,
Electric fan operating state detection means).

Claims (4)

[Claims] 1. A device for controlling a fuel pump for supplying fuel in a fuel tank to an engine side, the fuel temperature information detecting means for detecting information on a temperature of the fuel in the fuel tank, and an ignition switch being turned on. First determining means for determining off, second determining means for determining whether or not before engine start, and after the ignition switch is turned on, the fuel temperature is in a normal temperature range or a low temperature range and before engine start. When it is determined that the fuel pump is operated for a predetermined time, when the fuel temperature is in a high temperature region and before the engine is started, the fuel pump is operated for a time longer than the predetermined time. Characteristic fuel pump control device. 2. The fuel temperature information detecting means uses information from both or one of a cooling water temperature detecting means for detecting an engine cooling water temperature and an intake air temperature detecting means for detecting an intake air temperature as the information about the fuel temperature. The fuel pump control device according to claim 1, wherein the fuel pump control device is configured as follows. 3. The fuel temperature information detecting means is configured to use the information from the electric fan operating state detecting means for detecting the operating state of the radiator electric fan as the information on the fuel temperature. The fuel pump control device according to item 1. 4. The control means sets the operating time of the fuel pump, which is operated when the fuel temperature is in a high temperature region and before it is determined that the engine is started, to be longer as the fuel temperature becomes higher. The fuel pump control device according to any one of claims 1 to 3, characterized in that.