JPH0942109A - Fuel injection control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the leakage rate of fuel from an injector whose engine is stopped while ensuring startability by controlling fuel remained pressure in a fuel piping by reducing fuel pressure in the fuel piping according to a detected fuel temperature after operation of an internal combustion engine is stopped. SOLUTION: Fuel sucked by a fuel pump 11 arranged in a fuel tank 10 for remaining fuel is divided into the injector 13 of each cylinder passing a fuel piping 12. A fuel film 14 is arranged on the way of the fuel piping 12. Combustion pressure in the fuel piping 12 is automatically regulated by a pressure regulator 15 arranged on the downstream side of the injector 13 so as to set differential pressure of the intake negative pressure of an engine to a setting pressure. Remaining fuel supplied in the pressure regulator 15 is returned back in the fuel tank 10 through a return piping 16. A fuel temperature censor 17 and a combustion pressure sensor 18 are arranged in the fuel piping 12, and a relief valve 20 is arranged as a pressure bleeding means downstream therefrom.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for an internal combustion engine having a function of preventing fuel leakage from an injector that occurs when the internal combustion engine (engine) is stopped.

[0002]

2. Description of the Related Art Conventionally, for example, JP-A-6-50230.
As shown in the publication, a check valve is provided on the discharge port side of the fuel pump, and by keeping the residual fuel pressure in the fuel pipe at a high pressure without lowering it even when the engine is stopped, The high temperature restartability is improved by preventing the generation of vapor (fuel evaporative gas).

[0003]

However, if the residual fuel pressure in the fuel pipe is kept at a high pressure while the engine is stopped, a small amount of fuel leaks from the minute gap in the valve of the injector. This fuel leakage increases as the residual fuel pressure increases, and this causes the unburned gas component (HC) in the exhaust gas to increase at the time of engine start, which causes the emission to deteriorate. Conventionally, since the fuel pressure is set to a high value in order to secure the high temperature restartability, deterioration of the emission at the time of starting due to the above-mentioned fuel leakage has been a problem.

The present invention has been made in view of the above circumstances, and therefore an object thereof is to ensure the startability and to reduce the fuel leakage from the injector while the engine is stopped, and to start the engine. An object of the present invention is to provide a fuel injection control device for an internal combustion engine, which can improve the emission of the fuel.

[0005]

[Means for Solving the Problems] The residual fuel pressure required to secure startability varies depending on the fuel temperature. If the fuel temperature becomes low, it is possible to prevent the occurrence of vapor even if the residual fuel pressure is low. It is possible to secure good startability. Therefore, when the fuel temperature is low, it is possible to achieve both startability and prevention of fuel leakage from the injector by reducing the residual fuel pressure.

Focusing on this point, the fuel injection control device for an internal combustion engine according to claim 1 of the present invention comprises a fuel temperature detecting means for detecting the fuel temperature, and a pressure releasing means for lowering the fuel pressure in the fuel pipe. A residual pressure control means for controlling the residual fuel pressure in the fuel pipe by operating the pressure relief means in accordance with the fuel temperature detected by the fuel temperature detection means after the operation of the internal combustion engine (engine) is stopped. Has become.

With this structure, when the fuel temperature is low (that is, when good startability can be secured even when the residual fuel pressure is low).
In order to reduce the fuel leakage from the injector while the engine is stopped, the residual pressure control means operates the depressurizing means after the engine is stopped to reduce the residual fuel pressure to ensure startability.

Further, in claim 2, the depressurizing means is
It is configured to open when energized. This allows
Even when the pressure release means cannot be energized due to a failure or the like, the pressure release means can be maintained in the closed state to prevent the fuel pressure from decreasing during operation, and the operability is not impaired.

By the way, since the saturated vapor pressure characteristic (vapor generation characteristic in the fuel) varies depending on the fuel property (fuel composition), the residual fuel pressure required for ensuring startability varies depending on the fuel property even if the fuel temperature is the same.

Therefore, in claim 3, fuel property detection means for detecting the fuel property is provided, and the residual pressure control means variably sets the target fuel residual pressure during engine operation stop according to the fuel property. As a result, the target residual fuel pressure is set to be relatively low for a fuel that does not easily generate vapor, and the effect of preventing fuel leakage from the injector is enhanced.

Further, as the engine is stopped for a long time, the fuel temperature is lowered due to heat radiation, and eventually the fuel temperature is lowered to the level at which vapor does not occur even when there is almost no residual fuel pressure. In this temperature range, it is not necessary to control the residual pressure by the pressure relief means. Therefore, in the fourth aspect, the residual pressure control means determines when the fuel temperature detected by the fuel temperature detection means is equal to or lower than a predetermined temperature at which vapor does not occur. In addition, the residual pressure control by the pressure relief means is stopped to prevent unnecessary reduction of residual pressure and maintain good startability.

Further, in the present invention, the residual pressure control means stops the residual pressure control by the pressure relief means when the ignition switch is in the ON state, and keeps the pressure relief means in the closed state.
This prevents the fuel pressure from leaking from the pressure relief means during engine operation.

The above-mentioned claims 1 to 5 prevent the fuel leakage from the injector by controlling the residual fuel pressure in the fuel pipe. After the operation of the internal combustion engine is stopped, a post-stop control means is provided to keep the current flowing in the drive coil of each injector in the direction opposite to the direction of fuel injection for a predetermined time. In this way, by flowing a current in the direction opposite to that at the time of fuel injection through the drive coil of the injector, the valve of the injector is forcibly biased in the valve closing direction, and the seal pressure of the valve is increased to prevent fuel leakage.

Further, in claim 7, a fuel temperature detecting means for detecting the fuel temperature is provided, and the post-stop control means supplies a reverse current to the drive coil of each injector as the detected fuel temperature of the fuel temperature detecting means increases. Increase the energization time of. This is because fuel leakage from the injector occurs when vapor is generated in the fuel and the residual fuel pressure is high.As the fuel temperature increases, the fuel temperature decreases to a temperature at which vapor does not occur. This is because it takes a long time to do.

Further, in the eighth aspect, the post-stop control means increases the reverse current supplied to the drive coil of each injector as the detected fuel temperature of the fuel temperature detection means increases. This is because the higher the fuel temperature, the more the amount of vapor generated and the higher the fuel residual pressure. Therefore, in opposition to this, the reverse current flowing through the drive coil of the injector is increased and the valve sealing pressure is increased. is there.

According to a ninth aspect of the present invention, a main battery and a sub battery are provided, each injector is driven by using the main battery as a power source during engine operation, and the power source is switched to the sub battery after the engine operation is stopped. Reverse current is applied to the drive coil of each injector. This prevents the main battery from being consumed while the engine is stopped, makes the main battery last longer, and starts the engine even if the sub-battery that supplies the reverse current to the injector drive coil becomes "battery exhausted". Performance and drivability are not adversely affected.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. First, a schematic configuration of the entire fuel injection system will be described based on FIG. A fuel pump 11 is provided in the fuel tank 10 that stores fuel, and the fuel sucked up by the fuel pump 11 is distributed to the injector 13 of each cylinder through a fuel pipe 12. A fuel filter 14 for capturing dust in the fuel is provided in the middle of the fuel pipe 12.
The internal fuel pressure is automatically adjusted by the pressure regulator 15 provided on the downstream side of the injector 13 so that the differential pressure from the negative suction pressure of the engine becomes a set pressure. The surplus fuel sent into the pressure regulator 15 is returned to the fuel tank 10 through the return pipe 16. A fuel temperature sensor 17 (fuel temperature detecting means) for detecting the fuel temperature Tf and a fuel pressure P are provided in the fuel pipe 12.
A fuel pressure sensor 18 for detecting f is provided.

The fuel pump 11 has a check valve (not shown) built in on the discharge port side, and a relief valve 20 as a pressure releasing means provided downstream thereof. This relief valve 20
As shown in FIG. 2, the inlet port 21 communicating with the fuel pipe 12, the outlet port 22 opened in the fuel tank 10, the valve body 23 opening and closing the inlet port 21, and the valve body 23 The spring force of the spring 24 is such that when the fuel pressure in the fuel pipe 12 becomes equal to or higher than the system protection pressure,
Is set to open. Further, the valve body 23 is connected to the plunger 26 of the electromagnet 25 in order to forcibly open the valve body 23 at the time of fuel residual pressure control, which will be described later, and the electromagnet 25 is energized to move the valve body 23 to the spring 24. It is designed to be opened against. Incidentally, as the driving means for driving the valve element 23 to open, other actuators such as a motor may be used instead of the electromagnet 25.

The energization / disconnection of the electromagnet 25 of the relief valve 20 is controlled by the control circuit 27 based on the output signals of the fuel temperature sensor 17 and the fuel pressure sensor 18 in accordance with the residual fuel pressure control routine shown in FIG. This fuel residual pressure control routine is repeatedly executed at a predetermined cycle until the power source of the control circuit 27 is turned off in step 109, which will be described later, and functions as a residual pressure control means in the claims.

When the processing of the fuel residual pressure control routine is started, first, at step 101, it is judged whether the engine is stopped or not, for example, by whether an ignition switch (not shown) is off or not, and the engine is stopped. If not, the present routine is terminated without performing the subsequent processing. After that, when the ignition switch is turned off and the engine is stopped, the routine proceeds to step 102, where the fuel temperature Tf output from the fuel temperature sensor 17 is read, and at the next step 103, the fuel output from the fuel pressure sensor 18 is read. Read the residual pressure Pf.

In the next step 104, the step 10
The fuel temperature Tf read in 2 is compared with the predetermined temperature Tf0. Here, the predetermined temperature Tf0 is a temperature below which the vapor does not occur even if there is almost no residual fuel pressure, that is, the temperature at which fuel leakage from the injector 13 does not occur. Therefore, when the fuel temperature Tf is higher than the predetermined temperature Tf0 and it is necessary to control the fuel residual pressure, the fuel residual pressure control processing of steps 105 to 108 is performed. In this fuel residual pressure control process, first, in step 105, the target fuel residual pressure P
o is set from table data set in advance according to the fuel temperature Tf. In this table data, a value that approximates the saturated vapor pressure characteristic of the fuel is set (see FIG. 5), and the minimum required residual fuel pressure at which vapor does not occur at that fuel temperature is tabulated. This table data is set on the basis of a highly volatile saturated vapor pressure characteristic fuel. This is based on the fuel of low volatility, and when the fuel of high volatility is used, the fuel pipe 1
This is because there is a possibility that vapor will be generated in 2 and the high temperature restartability will be deteriorated.

In the next step 106, the step 10
The fuel residual pressure Pf read in step 3 is compared with the target fuel residual pressure Po obtained in step 105. If the fuel residual pressure Pf is higher than the target fuel residual pressure Po, the routine proceeds to step 107, where the electromagnet 25 of the relief valve 20 is set. The relief valve 20 is opened by energizing, the excess fuel in the fuel pipe 12 is released into the fuel tank 10, and the residual fuel pressure is reduced. On the other hand, the residual fuel pressure Pf
Is less than the target fuel residual pressure Po, the routine proceeds to step 108, where the energization of the electromagnet 25 of the relief valve 20 is turned off,
The relief valve 20 is closed to maintain the fuel residual pressure Pf near the target fuel residual pressure Po.

After that, as the time elapses, the fuel temperature T
When f becomes equal to or lower than the predetermined temperature Tf0 (temperature at which vapor is not generated), it is no longer necessary to perform the fuel residual pressure control, so the routine proceeds to step 109, where the power supply of the control circuit 27 is turned off to perform the fuel residual pressure control. finish.

FIG. 4 shows an example of changes over time in the power supply of the control circuit 27, opening / closing of the relief valve 20, residual fuel pressure Pf, and fuel temperature Tf when the residual fuel pressure control described above is performed. It is shown in the chart.

According to the first embodiment, after the engine is stopped, the fuel residual pressure Pf is maintained near the target fuel residual pressure Po (that is, the minimum required fuel residual pressure at which vapor does not occur) according to the fuel temperature Tf. Since the relief valve 20 is operated as described above, the residual fuel pressure Pf can be reduced according to the fuel temperature Tf within a range that does not impair the startability, and fuel leakage from the injector 13 during engine stop can be reduced. Therefore, the emission at the time of starting can be improved.

Moreover, since the relief valve 20 is opened when energized and is kept closed by the spring 24 when the electricity is cut off, even if the relief valve 20 cannot be energized due to a failure or the like, the relief valve 20 can be opened. By keeping the valve closed, it is possible to prevent a decrease in fuel pressure during operation, and it is possible to avoid impairing drivability.

Further, when the fuel temperature Tf becomes lower than a predetermined temperature Tf0 (temperature at which vapor is not generated), the control circuit 2
Since the power supply of No. 7 is turned off and the fuel residual pressure control is ended, it is possible to prevent unnecessary reduction of the residual pressure and to maintain good startability.

As shown in FIG. 5, the saturated vapor pressure characteristics (vapor generation characteristics in the fuel) differ depending on the fuel characteristics (fuel composition), so even if the fuel temperature Tf is the same, it is at least necessary for ensuring startability depending on the fuel characteristics. Fuel residual pressure (target fuel residual pressure Po) is different.

From this relationship, in the first embodiment,
Since the target fuel residual pressure Po is set on the basis of highly volatile fuel, if the fuel with low volatility is used, the target fuel residual pressure Po should be lowered a little further in order to further enhance the fuel leakage prevention effect. However, vapor does not occur, and good startability can be maintained.

Therefore, in the second embodiment shown in FIG.
The target residual fuel pressure Po is variably set according to the fuel property (volatility). Specifically, the fuel property sensor 19 (see FIG. 2) is used as a fuel property detection unit that detects the fuel property (volatility).
Is provided in the fuel pipe 12, and step 105 of FIG.
6 is changed to steps 105a and 105b in FIG. Other than this, it is the same as the first embodiment.

In this case, in step 105a, a signal corresponding to the fuel volatility Prvp output from the fuel property sensor 19 is read, and in the subsequent step 105b, the target residual fuel pressure Po is set to the fuel temperature Tf and the volatility Prvp. Calculated from a two-dimensional map. This map value setting is based on volatile Prvp
Since the higher the value is, the more easily vapor is generated, the target residual fuel pressure Po is set to be higher as the volatility Prvp is higher. In this embodiment, the target residual fuel pressure Po
The calculation of is performed by complementing with a map, but a plurality of preset table values may be switched according to the volatility Prvp (see FIG. 7).

Further, in the third embodiment shown in FIG. 8, the process of step 105 of FIG.
Change to 105d. Other than this, it is the same as the first embodiment.

In step 105c, the purge gas concentration Nrvp determined during execution of the purge for discharging the fuel evaporative gas (evaporative gas) adsorbed by the canister (not shown) to the intake pipe (not shown) of the engine is set to the volatile fuel. Is read as data indicating. The purge gas concentration Nrvp is calculated from the deviation amount of the air-fuel ratio during execution of the purge. In this case, the higher the volatility of the fuel, the more easily the evaporative gas is generated. Therefore, the higher the volatility of the fuel, the larger the deviation amount of the air-fuel ratio during purging. Therefore, the purge gas concentration Nrvp calculated from the deviation amount of the air-fuel ratio during purging is data that reflects the volatility of the fuel.

In the next step 105d, the target residual fuel pressure Po is set to the fuel temperature Tf and the purge gas concentration Nrvp (volatile).
Calculated from the two-dimensional map of This map value is set so that the higher the purge gas concentration Nrvp (volatile), the more easily vapor is generated.
The target residual fuel pressure Po is set to be higher as is higher. In this case, the calculation of the target residual fuel pressure Po is performed by complementing the map, but a plurality of preset table values may be switched according to the purge gas concentration Nrvp.

Further, in the fourth embodiment shown in FIG. 9, the processing of step 105 of FIG.
Change to 105f. Other than this, it is the same as the first embodiment.

In step 105e, the maximum value Ptnk of the fuel tank internal pressure detected by the fuel tank internal pressure sensor (not shown) during engine operation is read as data indicating the volatility of the fuel. In this case, the higher the volatility of the fuel, the more easily the evaporation gas is generated, and thus the higher the volatility of the fuel, the higher the maximum value Ptnk of the fuel tank internal pressure. Therefore, the maximum value Ptnk of the internal pressure of the fuel tank is data that reflects the volatility of the fuel.

In the next step 105f, the target residual fuel pressure Po is calculated from the two-dimensional map of the fuel temperature Tf and the maximum fuel tank internal pressure Ptnk (volatile). This map value is set so that the higher the maximum fuel tank internal pressure Ptnk (volatility), the more easily vapor is generated. Therefore, the higher the maximum fuel tank internal pressure Ptnk, the higher the target residual fuel pressure Po. Has been done. In this case, the target fuel residual pressure Po
The calculation of is performed by complementing with a map, but a plurality of preset table values may be switched according to the maximum fuel tank internal pressure Ptnk.

The fuel residual pressure control of each of the first to fourth embodiments described above is applied to the system for returning the surplus fuel from the injector 13 side into the fuel tank 10 through the return pipe 16. , Return piping 1
The same can be applied to the returnless piping system where 6 is abolished.

In each of the first to fourth embodiments described above, the fuel residual pressure in the fuel pipe 12 is controlled to prevent fuel leakage from the injector 13. However, other fuel leakage prevention is performed. As a method, after the operation of the engine is stopped, the drive coil 33 (see FIG. 10) of each injector 13 may be continuously supplied with a current in a direction opposite to the direction of fuel injection for a predetermined time.

A fifth embodiment of the present invention will be described below with reference to FIGS. 10 to 13. First, the structure of the injector 13 will be described with reference to FIG. The injector 13 has the same structure as that used in each of the first to fourth embodiments described above, and the structure itself is a general structure that has been conventionally used. Inside the housing 31 of the injector 13, a drive coil 33 wound around a spool 32 is mounted. A cylindrical iron core 34 that doubles as a fuel inflow pipe is fitted into the inner diameter portion of the spool 32. A fuel connector 36 connected to the fuel pipe 12 is provided at the upper end of the tubular iron core 34, and a filter 37 is mounted inside the fuel connector 36. An electric connector 38 is provided on the outer peripheral portion of the tubular iron core 34, and the drive coil 33 is energized through a connector pin 39 provided on the electric connector 38. Further, an adjusting pipe 40 and a spring 41 are mounted inside the tubular iron core 34, and a movable core 42 arranged below the tubular iron core 34 is urged downward by the spring 41.

On the other hand, a valve body 44 is caulked and fixed to the lower edge of the housing 31 via a spacer 43. A needle valve 45 is vertically movably housed in the valve body 44.
Has an upper end penetrating the spacer 43 and connected to the movable core 42. In addition, the needle valve 45 includes a spacer 4
3 is formed in the vicinity of the lower side of the movable core 42, and when the drive coil 33 is energized, the movable core 42 is moved to the spring 4
The needle valve 4 is sucked upward against the spring force of 1.
5 is slid upward until the stopper 46 contacts the spacer 43, and the injection hole 47 at the lower end of the valve body 44 is opened. Then, when the drive coil 33 is de-energized, the spring force of the spring 41 causes the needle valve 45 to slide downward, and the tip of the needle valve 45 is brought into pressure contact with the valve seat on the peripheral edge of the injection hole 47 and the injection hole 47. Is closed.

On the other hand, the electrical configuration is unique to this embodiment, and although not shown, two power sources of a main battery and a sub battery are provided. And FIG.
By the power switching routine shown in, while the engine is operating,
It is determined as “No” in step 201, and step 202
Then, the power is switched to the main battery, and the power is supplied from the main battery to the injector 13 of each cylinder. On the other hand, after the engine is stopped, in step 201, "Yes
s ”, the process proceeds to step 203, the power source is switched to the sub-battery, and power is supplied from the sub-battery to the injector 13 of each cylinder. Furthermore, the direction of the current flowing from the sub-battery to the drive coil 33 of the injector 13 after the engine is stopped is opposite to that at the time of fuel injection.

Next, the processing flow of the post-stop control routine shown in FIG. 12 will be described. This post-stop control routine is repeatedly executed at a predetermined cycle, and functions as a post-stop control means in the claims.

When the processing of this post-stop control routine is started, it is first determined in step 211 whether or not the engine is stopped, and if the engine is operating, this routine is terminated without passing a reverse current. . After that, when the engine is stopped, the routine proceeds to step 212, where the fuel temperature Tf is read. In the next step 213, the current value I flowing in the drive coil 33 of the injector 13 in the direction opposite to the fuel injection time is calculated from the map shown in FIG. At this time, the fuel temperature Tf
Is higher, the reverse current value I is increased. This is because as the fuel temperature Tf increases, the amount of vapor generated increases and the residual fuel pressure increases, so that the reverse current flowing through the drive coil 33 of the injector 13 is increased to counteract this and act on the needle valve 45. This is because the electromagnetic force in the valve closing direction is increased to increase the sealing pressure of the needle valve 45.

At the next step 214, the timer is operated, and at step 215, the reverse current is supplied to the drive coil 33 of the injector 13 at the current value I obtained at step 213. As a result, the needle valve 45 of the injector 13 is forcibly urged in the valve closing direction, the seal pressure of the needle valve 45 is increased, and fuel leakage is prevented.

Then, in step 216, it is determined whether or not a predetermined time has elapsed after the engine was stopped. If the predetermined time has not elapsed, the process returns to step 211 and the above-mentioned processing is repeated. Here, the predetermined time is the injector 13
This is the time until the fuel temperature can be prevented by only the spring force of the spring 41 in the injector 13 even if a reverse current is not applied to the drive coil 33. Therefore, after the lapse of a predetermined time, the reverse current becomes unnecessary,
In step 217, the reverse current is turned off and this routine ends. If the engine is restarted before the elapse of the predetermined time, the process proceeds from step 211 to step 2
The routine jumps to 17, the reverse current is turned off, and this routine ends.

In the fifth embodiment described above, two power sources, a main battery and a sub battery, are provided, and after the engine operation is stopped, the power source is switched from the main battery to the sub battery and the drive coil 33 of the injector 13 is driven in the reverse direction. Since the current is made to flow, the main battery can be prevented from being consumed while the engine is stopped, and the main battery can be made to last longer. Even if the sub-battery that makes a reverse current flow to the drive coil 33 of the injector 13 is "battery exhausted". Even if it becomes the state of "", it does not affect the engine startability and drivability.

Further, in the fifth embodiment, considering that the higher the fuel temperature Tf is, the more the amount of vapor generated and the more fuel leakage is likely to occur, the higher the fuel temperature Tf is, the reverse current value is increased. Since I is increased, it is possible to prevent fuel leakage with a minimum necessary reverse current according to the fuel temperature Tf, and to reduce battery power consumption.

However, according to the present invention, the reverse current value I
May be fixed to a constant value (however, it should be set to a current value capable of preventing fuel leakage even when the fuel temperature Tf is high), and even in this case, the intended purpose of the present invention can be sufficiently achieved.

Further, in the fifth embodiment, the time for flowing the reverse current is constant, but as in the sixth embodiment shown in FIG. 14, the higher the fuel temperature Tf is (that is, the fuel temperature Tf is It is also possible to increase the energization time of the reverse current flowing through the drive coil 33 of the injector 13 as the time until the temperature at which vapor does not occur decreases.

Specifically, the reverse current energization time Time0 is set according to the fuel temperature Tf read immediately after the engine is stopped (steps 221 to 223). After that, the timer is activated and the drive coil 3 of the injector 13 is activated.
A reverse current is supplied to the circuit 3 at a preset current value (steps 224 and 225). Then, the reverse current conduction time T
It is determined whether or not ime has reached the time Time0 set in the above step 223 (step 226), and if the time Time0 has not been reached yet, the reverse current continues to flow. However, if the engine is restarted midway, the process proceeds from step 227 to step 228, the reverse current is turned off, and this routine is ended.

In the sixth embodiment, the reverse current is set to a preset constant value. However, as in the fifth embodiment, the reverse current is reduced as the fuel temperature Tf decreases with the passage of time. The current may be reduced. By doing so, the amount of battery power consumption can be kept to a necessary minimum.

In both the fifth and sixth embodiments described above,
Although the time for flowing the reverse current is counted by the timer, as in the seventh embodiment shown in FIG. 15, the reverse current is supplied until the fuel temperature Tf drops to the preset temperature To. You can In the seventh embodiment, the processing of step 214 in FIG. 12 described above is omitted,
The process of step 216 is changed to step 216a of FIG. 15, and other than that is the same as the process of FIG. In the seventh embodiment, the time until the fuel temperature Tf falls to the preset temperature To corresponds to the predetermined time in the claims.

In each of the above embodiments, the fuel temperature is directly detected by the fuel temperature sensor 17, but the engine cooling water temperature, the oil temperature, and the engine temperature, which are correlated with the fuel temperature, are detected to determine the fuel temperature. It may be estimated.

[0055]

As is apparent from the above description, according to the structure of claim 1 of the present invention, the depressurizing means is operated in accordance with the fuel temperature to lower the residual fuel pressure in the fuel pipe. As a result, fuel leakage from the injector while the engine is stopped can be reduced while ensuring startability, and emission at the time of start can be improved.

Further, in the present invention, since the pressure relief means is opened when energized, even if the pressure relief means cannot be energized due to a failure or the like, the pressure relief means can be kept closed. It is possible to prevent a decrease in fuel pressure during operation, and the drivability is not impaired.

In the third aspect, the target residual fuel pressure during engine operation stop is variably set according to the fuel property.
Residual pressure control can be performed according to the fuel property, and startability and fuel leakage prevention performance can both be achieved at a high level.

Further, in claim 4, the residual pressure control is stopped when the fuel temperature becomes equal to or lower than a predetermined temperature at which vapor does not occur. Therefore, it is possible to prevent unnecessary reduction of the residual pressure and to start the engine. It is possible to maintain good sex.

Further, according to the present invention, the residual pressure control is stopped when the ignition switch is turned on. Therefore, it is possible to reliably prevent the fuel pressure from leaking from the pressure relief means during the engine operation. it can.

According to the sixth aspect of the present invention, after the engine operation is stopped, the current in the direction opposite to that at the time of fuel injection is kept flowing through the drive coil of the injector for a predetermined time. Therefore, the valve of the injector is forcibly closed after the engine operation is stopped. The seal pressure of the valve can be increased by urging the valve in the direction, and fuel leakage can be prevented.

Further, in claim 7, the higher the fuel temperature, the longer the energizing time of the reverse current flowing through the drive coil of the injector. Therefore, the reverse direction can be changed depending on the occurrence of vapor which causes fuel leakage. The current energization time can be set to an appropriate time, and the reverse current can be energized without excess or deficiency.

Further, according to the eighth aspect, since the reverse current is changed according to the fuel temperature, the fuel leakage can be prevented with the minimum necessary reverse current according to the fuel temperature, and the battery power can be reduced. The consumption can be reduced.

Further, in the present invention, after the engine is stopped, the power source is switched from the main battery to the sub-battery so that the reverse current is supplied to the drive coil of the injector. Therefore, the main battery is consumed while the engine is stopped. The main battery can be prevented and the main battery can last a long time, and even if the sub-battery that supplies the reverse current is in the "battery exhausted" state, the startability and drivability of the engine are not adversely affected.

[Brief description of drawings]

FIG. 1 is a flowchart showing a processing flow of a fuel residual pressure control routine in a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a schematic configuration of the entire system.

FIG. 3 is a diagram schematically showing the configuration of a relief valve.

FIG. 4 is a time chart showing a flow of residual fuel pressure control.

FIG. 5 is a diagram showing a saturated vapor pressure characteristic of typical gasoline.

FIG. 6 is a flowchart showing a processing flow of a main part of a fuel residual pressure control routine according to the second embodiment of the present invention.

FIG. 7 is a diagram showing a map defining a relationship between a fuel temperature Tf and a target residual fuel pressure Po.

FIG. 8 is a flowchart showing a processing flow of a main part of a fuel residual pressure control routine in the third embodiment of the invention.

FIG. 9 is a flowchart showing a processing flow of a main part of a fuel residual pressure control routine according to a fourth embodiment of the present invention.

FIG. 10 is a vertical sectional view showing the structure of an injector.

FIG. 11 is a flowchart showing a processing flow of a power supply switching routine according to the fifth embodiment of the present invention.

FIG. 12 is a flowchart showing the flow of processing of a post-stop control routine in the fifth embodiment of the present invention.

FIG. 13 is a diagram showing a map defining a relationship between a fuel temperature Tf and a reverse current value I.

FIG. 14 is a flowchart showing a processing flow of a post-stop control routine according to the sixth embodiment of the present invention.

FIG. 15 is a flowchart showing a processing flow of a post-stop control routine according to the seventh embodiment of the present invention.

[Explanation of symbols]

10 ... Fuel tank, 11 ... Fuel pump, 12 ... Fuel piping, 13 ... Injector, 15 ... Pressure regulator, 16 ... Return piping, 17 ... Fuel temperature sensor (fuel temperature detecting means), 18 ... Fuel pressure sensor, 19 ... Fuel property Sensor (fuel property detection means), 20 ... Relief valve (pressure release means), 23 ... Valve body, 24 ... Spring, 25 ... Electromagnet, 27 ... Control circuit (residual pressure control means), 33 ... Drive coil, 34 ... Cylinder Iron core, 42 ... Movable core, 41 ... Spring, 45 ... Needle valve, 47 ... Injection hole.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location F02M 69/00 F02M 69/00 320J

Claims (9)

[Claims] 1. A fuel temperature for detecting a fuel temperature in a fuel injection control device for an internal combustion engine, wherein fuel in a fuel tank is sent from a fuel pump to an injector of each cylinder through a fuel pipe, and fuel is injected from each injector to each cylinder. Detecting means, depressurizing means for lowering the fuel pressure in the fuel pipe, and operating the depressurizing means in accordance with the detected fuel temperature of the fuel temperature detecting means after stopping the operation of the internal combustion engine A fuel injection control device for an internal combustion engine, comprising: a residual pressure control means for controlling a residual fuel pressure. 2. The fuel injection control device for an internal combustion engine according to claim 1, wherein the depressurizing means is configured to open when energized. 3. A fuel property detection means for detecting a fuel property, wherein the residual pressure control means variably sets a target fuel residual pressure during operation stop of the internal combustion engine according to the fuel property. The fuel injection control device for an internal combustion engine according to claim 1 or 2. 4. The residual pressure control means stops the residual pressure control by the pressure relief means when the fuel temperature detected by the fuel temperature detection means falls below a predetermined temperature. 4. A fuel injection control device for an internal combustion engine according to any one of 3 above. 5. The internal combustion engine according to claim 1, wherein the residual pressure control means stops the residual pressure control by the pressure relief means when the ignition switch is in an on state. Fuel injection control device. 6. A fuel injection control device for an internal combustion engine, wherein fuel in a fuel tank is sent from a fuel pump to an injector of each cylinder through a fuel pipe, and fuel is injected from each injector to each cylinder. A fuel injection control device for an internal combustion engine, comprising: post-stop control means for continuously supplying a current in a direction opposite to a direction during fuel injection to a drive coil of each injector for a predetermined time. 7. A fuel temperature detecting means for detecting a fuel temperature, wherein the post-stop control means conducts a reverse current for a current flowing through the drive coil of each injector as the detected fuel temperature of the fuel temperature detecting means increases. 7. The fuel injection control device for an internal combustion engine according to claim 6, wherein 8. The internal combustion engine according to claim 7, wherein the post-stop control unit increases the reverse current flowing through the drive coil of each injector as the detected fuel temperature of the fuel temperature detection unit increases. Engine fuel injection control device. 9. A main battery and a sub-battery are provided, wherein each of the injectors is driven by using the main battery as a power source during operation of the internal combustion engine, and the power source is supplied to the sub-battery after the operation of the internal combustion engine is stopped. 9. The fuel injection control device for an internal combustion engine according to claim 6, wherein a reverse current is applied to the drive coil of each injector by switching the current.