JP2917887B2 - Engine fuel control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine fuel control apparatus suitable for ensuring high temperature restart in a fuel injection type engine using an injector.

[0002]

2. Related Art In an engine of a type in which fuel is directly injected by using an injector, startability at the time of high-temperature restart may become a problem. That is, when fuel is not injected from the injector to which fuel has been supplied, it is unavoidable that fuel slightly leaks from the seat portion into the port. Generally, after the fuel supply is stopped due to the stoppage of the engine, the leaked fuel gradually diffuses and disappears through an exhaust system or the like as time passes. However, if the engine is restarted within a short time after the engine is stopped, the leaked fuel will not be sufficiently diffused, and will remain in the port in a vaporized state due to the high remaining temperature of the engine.
For this reason, if the starting fuel for the restart is supplied in this state, the air-fuel ratio becomes over-rich, and there is a possibility that starting the engine becomes difficult.

Japanese Patent Application Laid-Open No. Hei 4-58032 discloses that at the initial stage of starting, in addition to the fuel required by the engine, fuel expected to adhere to the intake manifold is supplied. It is disclosed that when the engine is restarted, the fuel supply at the start of the start is stopped and only the fuel supply at the latter stage of the start is performed. However, the fuel supply control method disclosed in this publication is based on the viewpoint that a part of the fuel to be supplied at the initial stage of start-up adheres to the intake manifold, and as a result, the amount of fuel supplied to the engine is substantially insufficient. No measures have been taken for starting failures caused by fuel leakage from the injectors when the engine is restarted at a high temperature.

Japanese Patent Application Laid-Open No. Hei 5-296084 discloses that
The time from the stop of the engine to the restart is measured, and when the elapsed time is shorter than a predetermined time, the fuel injection amount is reduced in accordance with the elapsed time. It is disclosed that the fuel injection amount is corrected according to a difference in temperature at the time of restart. However, the fuel supply control method disclosed in this publication basically focuses on the elapsed time from engine stop to restart and changes the fuel injection amount and corrects this in accordance with the temperature difference. It is not possible to appropriately cope with the cause of the starting failure at the time of high temperature restart, specifically, the degree of fuel leakage in the injector. In particular, there is a problem that it is not possible to cope with a difference in the amount of fuel leakage between individual injectors and a change with time of the amount of fuel leakage.

[0005]

SUMMARY OF THE INVENTION By the way, Japanese Patent Application Laid-Open No. Hei 7-3
In JP-A-4928, the time required for starting the engine (starting time) is measured, the fuel leakage in the injector is determined from the measured starting time and the learning value, and the learning value is updated (starting time learning). It is disclosed that the determination result is stored, and the fuel injection amount is reduced and corrected at the time of restart according to the stored determination result. However, according to the fuel control method disclosed in this publication, fuel leakage is determined based on the start time and the learned value while learning the start time, but the fuel injection amount reduction correction based on the determination result is performed in the next time. Performed at restart.
For this reason, when the engine is restarted at a high temperature in a state where the elapsed time from the stop of the engine is short, the amount of fuel injection is reduced in anticipation of leaked fuel, which is effective in improving the startability. However, after the engine is stopped, for example, when the engine is restarted after a long time, even if the fuel leaked from the injector is diffused and substantially disappeared, the fuel injection amount is reduced. Is performed, there is a risk that the startability may be worsened.

The present invention has been made in view of such circumstances, and an object of the present invention is to improve the startability at the time of a high-temperature restart caused by fuel leakage in an injector and to ensure the start. An object of the present invention is to provide an engine fuel control device.

[0007]

In order to achieve the above object, a fuel control apparatus for an engine according to the present invention comprises: a high temperature restart determining means for determining whether or not the engine has been started in a high temperature state; When a high-temperature restart state is detected by the start determination unit, a start-up fuel control unit that controls to reduce a start-up fuel amount given to the injector in accordance with the stored fuel reduction ratio; When a restart is detected, an injector leak determining means for determining a fuel leak in the injector at the time of the restart, and when a fuel leak is detected by the injector leak determining means, the fuel reduction ratio is set to a predetermined amount. and a learning means for updating, in particular the learning means, when hot restart
Each time an injector leak is detected, the fuel reduction
Is updated by a predetermined amount until a predetermined ratio is reached.
Learning, and the fuel reduction rate is specified in advance.
When the set ratio is reached, the fuel reduction ratio is initially set to [0].
It is characterized in that

That is, it is determined whether or not the engine has been started in a high temperature state, and when a high temperature restart is detected, the starting fuel amount is controlled to be reduced according to the fuel reduction ratio stored in the memory. . Further, when the high-temperature restart state is detected, the presence or absence of fuel leakage in the injector is determined from the starting time, and when fuel leakage is detected, the fuel reduction ratio is updated and learned by a predetermined amount and learned. By reflecting the learning result at the next high temperature restart, the problem of fuel leakage at the injector can be avoided,
It is characterized in that the engine can be reliably started regardless of the starting environment of the engine or the situation at the time of starting.

Further preferred embodiments of the present invention, the determination of the hot restart condition, it is characterized by performing on the basis of the engine temperature at the engine temperature and the current at the previous key-off.

[0010] Further, a preferred embodiment of the present invention relates to the above-mentioned ink jet printer.
The determination of fuel leak by the injector leak determination means
Based on the time required to start the engine in the starting state
It is characterized by performing.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An engine fuel control apparatus according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of the embodiment device, and FIG. 2 is a timing diagram schematically showing a control form of fuel injection at the time of starting in a six-cylinder engine.

In this embodiment, an electronic control unit (E
An ignition (IG) switch 2 for controlling the start / stop of the engine 2, a water temperature sensor for detecting the temperature of the engine cooling water 3, and attached to a crankshaft to determine a specific crank angle of each cylinder. Signal
A crankshaft sensor 4 that outputs the SGT in synchronization with its rotation and a camshaft that is attached to the camshaft that rotates in synchronization with the crankshaft, and synchronizes a cylinder identification signal SGC of a specific pattern associated with each cylinder with that rotation. And output the signals from the camshaft sensor 5 and output to the injectors (INJ) 6a, 6b, 6c, 6d, 6d,
It is configured to control the fuel injection at 6e and 6f, respectively.

Although a six-cylinder engine is described here as an example, the present invention can be similarly applied to other multi-cylinder engines such as a four-cylinder engine and an eight-cylinder engine. Then, the ECU 1 receives the signal SG from the crankshaft sensor 4.
Based on T and the cylinder identification signal SGC from the camshaft sensor 5, for example, a cylinder identification unit 11 for identifying a cylinder going to an intake stroke (combustion stroke), and the injectors 6a, 6b, 6c, An injection control unit 12 for controlling fuel injection from 6d, 6e, and 6f, respectively. When the ignition switch 2 is turned on and the engine is started, as shown in FIG. 2, the injection control unit 12 basically transmits a specific crank angle position indicated by a signal SGT from the crankshaft sensor 4, For example, non-synchronous fuel injection is performed only once for all cylinders at a timing (TDCB5 °) 5 ° before the crank angle with respect to the top dead center (TDC) of the piston in each cylinder (start-time asynchronous injection control). Then, until a specific cylinder is identified by the cylinder identification unit 12, a predetermined amount of fuel is simultaneously injected into all cylinders at every timing (TDCB 75 °) 75 ° before the crank angle in each cylinder. Then, the injectors 6a, 6b, 6c, 6d, 6e, 6f are driven (simultaneous injection control). When a specific cylinder is identified by the cylinder identification unit 12, the injectors 6a, 6b, 6c, 6d, 6c, 6d, 6c, 6d, and so on are thereafter injected such that fuel is sequentially injected in a predetermined combustion order for each cylinder based on the identification result. 6e, 6f
Is driven (sequential injection control).

A variety of cylinder identification techniques have been proposed in the cylinder identification section 11 and do not show the essential features of the fuel injection control in the present invention. However, various cylinder identification methods can be appropriately adopted. Here, the present apparatus is characterized in that, in addition to the above-described cylinder identification unit 11 and injection control unit 12, when the engine is stopped, the engine temperature at that time is taken as a cooling water temperature WT, and a water temperature memory 13 for holding the same is provided; When the engine starts, the above water temperature memory 1
3, based on information from the ignition switch 2 and the water temperature sensor 3 while referring to the water temperature at the time of the previous stop of the engine stored in Engine is P
A PCD determination unit 14 that determines whether or not a CD (Partial Cool Down) state is provided. Furthermore, this P
When the CD determination section 14 determines that the PCD state is established, the injectors 6a, 6b, 6c, 6d, 6e, and 6f are described later based on information from the ignition switch 2 and the water temperature sensor 3. Is provided with an injector leak determination unit 15 for determining whether or not fuel leakage has occurred.

When the fuel leakage is detected by the injector leakage determination unit 15, the fuel injection learning unit 16 determines the reduction rate of the fuel injection amount at the time of startup stored in the fuel reduction rate memory 17 as described later. And the above-described reduction ratio stored in the fuel reduction ratio memory 17 is updated. Then, the injection control unit 12 determines the start of the engine according to the determination result of the PCD determination unit 14,
When it is determined that the start condition of the engine is the PCD state, the starting fuel is reduced and controlled according to the fuel reduction ratio stored in the fuel reduction ratio memory 17. Specifically, the fuel in the asynchronous injection which is executed only once at the first time when the engine is started is reduced, and further, the fuel in the simultaneous injection performed until the specific cylinder is identified is reduced. It is something to do.

When it is determined that the vehicle is not in the PCD state or that no fuel leakage has occurred, the injection control unit 12 does not refer to the fuel reduction ratio memory 17 and determines in advance in each of the above-described fuel injection modes. The control operation is executed to inject each of the predetermined amount of fuel. Next, the above-described PCD determination, injector leak determination, and learning of the fuel reduction ratio will be described. These processes are performed, for example, according to the processing procedure shown in FIG.

This procedure is performed, for example, when starting the manufactured engine for the first time, or when the injectors 6a, 6b,
When the parameters 6c, 6d, 6e, and 6f are replaced, the parameter n relating to the control is set to [0], and the initial value is set to the value stored in the fuel reduction ratio memory 17 to [0]. Is performed (step S1). The initial setting procedure shown in step S1 is not executed when the engine is started other than the above-described execution conditions.

When the key-on of the ignition switch 2 is detected (step S2), first, the PCD
The determination unit 14 refers to the water temperature memory 13 and determines whether or not the water temperature at the time of the previous key-off (when the engine is stopped) was a predetermined temperature, for example, 80 ° C. or higher (step S3). Thereafter, if the previous water temperature was equal to or higher than 80 ° C., then the water temperature immediately before the current engine cranking (when the starter is turned on) is within a predetermined temperature range, for example, a range of 40 to 70 ° C. It is determined whether or not it is (step S4).

When both of these determination conditions are satisfied, that is, when the water temperature at the time of the previous key-off is 80
If the temperature is not lower than 0 ° C. and the water temperature at the time of restarting the engine this time is in the range of 40 to 70 ° C., it is determined that this is the PCD state. The fuel reduction ratio menu in this case
The fuel to be injected at the time of starting is reduced (step S5) with reference to the fuel reduction ratio stored in the wood 17 and the injection controller 12 is driven to reduce the reduced fuel to the injectors 6a, 6b, 6b. The engine is started by injection from 6c, 6d, 6e, 6f (step S6).

On the other hand, when it is determined that the water temperature at the time of the previous key-off is less than 80 ° C., or when the water temperature at the time of restarting the engine this time is not within the range of 40 to 70 ° C. Sometimes, it is determined that this is not the PCD state. Then, in this case, the engine is started by driving the injection control unit 12 without referring to the fuel reduction ratio memory 17 (step S6). Therefore PC
At the time of normal engine start not in the D state, a predetermined amount of fuel set in advance is injected according to the above-described fuel injection mode at start.

That is, if the water temperature at the time of the previous key-off is less than 80 ° C., it means that the engine is not heated, or the water temperature immediately before cranking is 40 °.
If it is out of the range of ~ 70 ° C, it is determined that the engine is not in the PCD state. If the PCD is not in the state, even if a predetermined amount of starting fuel is supplied at the time of the start, there is no possibility that the air-fuel ratio becomes over-rich and the start becomes difficult.
To start the engine by supplying the usual starting fuel.

Thereafter, it is determined whether or not the engine was started in the PCD mode on the basis of the above-described determination result (step S7). to start. However, if it is a normal engine start, that is, if the starting fuel control with reference to the fuel reduction ratio memory 17 has not been performed, the process waits for the engine to be turned off without performing any special processing procedure (step S8). If a key-off is detected, the water temperature at that time is stored in the water temperature memory 1.
3 for the next engine start (step S
9), the above-described series of processing procedures ends.

On the other hand, in step S7, P
If it is determined that the engine is to be started in the CD mode, the injector leak determination unit 15 measures the first startup time after the key is turned on, and determines whether or not a predetermined time has been spent for the startup. (Step S
10). This starting time is determined, for example, by the ignition
The time is measured by the switch 2 as the time during which the engine is cranking. Alternatively, the engine speed is obtained from the signal STG from the crankshaft sensor 4 and measured as the elapsed time from the start of the cranking until the speed reaches a predetermined starting speed, for example, 600 rpm.
Alternatively, by determining whether or not the engine is started within a predetermined time from the start of cranking, the start time is confirmed.

If the starting time determined in this way exceeds a predetermined value, it is determined that the starting is defective, and it is considered that the cause is fuel leakage in the injector. That is, the possibility that fuel leakage has occurred is detected.
If the starting time is shorter than the above-mentioned predetermined value, it is indicated that the engine has been started immediately with the start of cranking, and in this case, a starting failure due to fuel leakage or the like has not occurred. That is, it is determined that there is no fuel leakage. If no fuel leak is detected, the parameter n is set to [0] (step S11), and the process returns to the key-off detection process shown in step S8.

On the other hand, when the possibility of fuel leakage is detected as described above, the parameter n is incremented (step S12), and it is determined whether or not the parameter n exceeds a predetermined value (step S12). S13). This determination is for confirming whether or not the possibility of the fuel leakage is repeatedly detected a plurality of times in the start of the engine in the PCD mode. For example, the fuel leakage is continuously performed three times. When the possibility is detected, the parameter n becomes [3], which leads to a result that the cause of the starting failure at that time is a fuel leak in the injector. Conversely, if the parameter n is less than the predetermined value,
In this case, the process directly returns to the key-off detection process shown in step S8 because there is a possibility that there is another cause of the start failure.

When the engine is started in the first PCD mode, it is determined that there is a fuel leak, and the parameter n
Is set to [1], and if it is determined that the mode is not the PCD mode at the time of the next engine start, the normal start-up fuel injection is performed according to the above-described processing procedure, and the engine is started. Therefore, in this case, since the process of determining fuel leakage is not performed, the value of the parameter n is maintained as it is. Thereafter, when it is determined that the engine is in the PCD mode at the time of the next engine start, a second fuel leak determination is made at that time. At this time, if a fuel leak is detected, the parameter n is incremented to [2] (step S12). Conversely, if no fuel leak is detected, the parameter n is reset to [0]. (Step S11).

Under the control of the parameter n, P
It is determined whether or not fuel leakage in the CD mode is continuously and repeatedly detected. This eliminates accidental start-up delay caused by factors other than fuel leakage, thereby reliably preventing fuel leakage from the injector. It is something to judge.
When the fuel leak in the injector is detected as described above, the fuel injection learning unit 1
6 is activated. Then, under the control of the learning unit 16, the reduction ratio stored in the fuel reduction ratio memory 17 is updated by a predetermined amount (step S14). The update of the reduction ratio is performed, for example, by adding a predetermined amount of the injected fuel during normal operation to one.
Each time, a reduction ratio is increased so that the reduction ratio is increased by 0%. After updating the fuel reduction ratio in this manner, it is determined whether or not the reduction ratio has reached a predetermined value (step S15), and it is confirmed that the reduction ratio has not reached the predetermined value, and the processing from step S8 described above is performed. Return to. As a result, the PCD mode is determined at the next engine start, and when controlling the injected fuel with reference to the fuel reduction ratio memory 17, the ratio of the fuel to be reduced is stored in the fuel reduction ratio memory 17. According to the ratio, the fuel at the time of starting is reduced by a predetermined amount and injected.

It should be noted that the fuel reduction ratio is a predetermined value, for example, 50
%, On the contrary, the engine may become over-lean, making it difficult to start the engine. In this case, the fuel reduction ratio memory 17 is reset (step S16), and the steps S8 to S8 are repeated. It returns to the processing of. Therefore, in this case, the above-described fuel reduction control at the time of starting is repeated from the beginning.

Thus, according to the present apparatus for performing the control for reducing the fuel injected at the start in the PCD mode under the above-described processing procedure, it is determined that the state of the engine at the time of the start is the high temperature restart (PCD). Then, the starting fuel is reduced in accordance with the reduction ratio stored in the fuel reduction ratio memory 17. If the startability is poor in spite of executing the start-time fuel reduction control and fuel leakage from the injector is detected even at that time,
The reduction ratio in the fuel reduction ratio memory 17 is updated.
At the next engine start, if the engine startability in the PCD mode is improved by the start fuel reduction control based on the updated reduction ratio, the fuel reduction ratio memory 17 is updated. In other words, in other words, the reduction ratio obtained in the fuel reduction ratio memory 17 is maintained as it is and is used for the fuel control at the start in the PCD mode.

Therefore, in anticipation of fuel leakage from the injector, which is a problem in the PCD mode, it is possible to reduce and control the fuel at the time of the start and to always optimize the air-fuel ratio at the time of the start. Can be raised enough. In addition, since the reduction rate of the fuel at startup is updated in accordance with the starting environment of the engine and its starting condition, the learning effect is high. For example, as long as the degree of fuel leakage (leakage characteristic) does not change by replacing the injector,
There are advantages such as the effect can be maintained.

The present invention is not limited to the above embodiment. For example, the predetermined values used in the various determinations described in the processing procedure shown in FIG. 3 may be determined according to the specifications of the engine and the control standards.
Also, the overall flow of the processing procedure can be appropriately changed in relation to another control target in the ECU 1. In addition, various modifications can be made without departing from the scope of the invention.

[0032]

As described above, according to the present invention, it is determined whether or not the engine has been started in a high temperature state. When the high temperature restart is detected, the engine is started according to the fuel reduction ratio stored in the memory. The fuel amount at start is controlled to be reduced, and when the high-temperature restart state is detected, the presence or absence of fuel leakage at the injector at the time of restart is determined, and the fuel reduction ratio is updated and learned by a predetermined amount. So
Even if fuel leakage from the injector becomes a problem during a high temperature restart, the engine can be started reliably, and the engine startability can be improved regardless of the engine start environment and starting conditions. it can. In addition, according to the present invention, it is possible to effectively learn the reduction ratio of the fuel at the time of starting in response to the injector leakage at the time of high-temperature restart, and to effectively reflect the reduction in the engine start control.

Particularly, in the learning means, a high-temperature restart
Every time an injector leak is detected, the fuel
Update the ratio by a predetermined amount until the ratio reaches the predefined ratio
Learning is performed by performing
When the specified ratio is reached, the fuel reduction ratio is set to [0].
Initializing, the learning effect is high and unwilling
The control can be prevented from being executed.

In a preferred embodiment of the present invention,
Engine temperature at key-off and current engine
The high temperature restart state is determined based on the temperature.
By doing so, the decision itself can be made easily and reliably
Becomes possible. In addition, the engine
Fuel in the injector based on the time required for startup
By making a leak judgment, it is indirect but
Simplify and ensure that startability is not deteriorated due to fuel leakage.
It is possible to obtain effects such as being able to turn off.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a fuel control device for an engine according to an embodiment of the present invention.

FIG. 2 is a timing chart showing a mode of fuel injection control at start-up in the embodiment device.

FIG. 3 is a diagram showing an example of a PCD mode determination, a fuel leak determination, and a fuel reduction ratio update processing procedure in the apparatus of the embodiment.

[Description of Signs] 1 Electronic control unit (ECU) 2 Ignition switch 3 Water temperature sensor 4 Crank shaft sensor 5 Cam shaft sensor 6a, 6b, 6c, 6d, 6e, 6f Injector 11 Cylinder identification unit 12 Injection control unit 13 Water temperature memory 14 PCD determination unit 15 Injector leak determination unit 16 Injected fuel reduction learning unit 17 Fuel reduction ratio memory

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-34928 (JP, A) JP-A-63-38638 (JP, A) JP-A-2-221660 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) F02D 41/06 330 F02D 41/04 330 F02D 41/22 325 F02D 45/00 340 F02D 45/00 345

Claims (1)

(57) [Claims] 1. A high-temperature restart judging means for judging whether or not the engine has been started in a high-temperature state, and a fuel stored when a high-temperature restart state is detected by the high-temperature restart judging means. A start-up fuel control means for reducing and controlling a start-up fuel amount given to the injector according to the reduction ratio, and when a high-temperature restart is detected by the high-temperature restart determination means,
An injector leakage determining means for determining fuel leakage in the injector at the restart time when the fuel leakage is detected by the injector leak determination means, the fuel reduction ratio; and a learning means for a predetermined amount update The learning means detects injector leakage at the time of high temperature restart.
Each time the fuel is issued, the fuel reduction rate is set to a predetermined rate.
Is updated by a predetermined amount until
When the fuel reduction ratio reaches a predetermined ratio, the fuel
A fuel control device for an engine, wherein a fuel reduction ratio is initialized to [0] .