JP4581756B2 - Evaporative fuel processing equipment - Google Patents

Description

  The present invention relates to an evaporated fuel processing apparatus, and more particularly to an evaporated fuel processing apparatus for supplying evaporated fuel to individual cylinders when an internal combustion engine is started.

  Conventionally, for example, as disclosed in Japanese Utility Model Laid-Open No. 6-37548, a canister that adsorbs evaporated fuel generated inside a fuel tank is provided, and the evaporated fuel adsorbed inside the fuel tank is removed during operation of the internal combustion engine. Devices for inhaling an internal combustion engine are known.

  More specifically, this apparatus includes a purge passage that connects the canister and the intake passage of the internal combustion engine, and a control valve that controls the conduction state of the purge passage. The control valve is duty-driven, thereby changing the flow resistance of the purge passage and controlling the flow rate of the evaporated fuel flowing from the canister toward the intake passage.

  The above-described conventional apparatus can cause the evaporated fuel adsorbed by the canister to flow into the cylinder of the internal combustion engine by appropriately driving the control valve with a duty during the operation of the internal combustion engine. In particular, this apparatus drives the control valve so that a larger amount of evaporated fuel is purged during cold start of the internal combustion engine than during normal operation. Since the evaporated fuel is already vaporized, if the evaporated fuel is supplied in a large amount at the cold start, the internal combustion engine shows a good startability. For this reason, according to the conventional apparatus, it is possible to give a good startability to the internal combustion engine.

Japanese Utility Model Publication No. 6-37548 JP-A-8-200166

  However, in the above-described conventional apparatus, when purging the evaporated fuel at the start of the internal combustion engine, special characteristics at the start are not sufficiently considered.

  That is, when starting the internal combustion engine, unlike the normal operation, sufficient intake negative pressure is not generated. For this reason, if the control valve is opened and closed in the same manner as during normal operation, a sufficient amount of evaporated fuel cannot be supplied to each cylinder in a sufficiently mixed state.

  Also, when the internal combustion engine is started, it is impossible to know what state each cylinder is in until the cylinder discrimination signal is generated. Accordingly, a period during which ignition cannot be performed occurs at least for a certain period after the internal combustion engine is started. Further, during that period, the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke are sequentially repeated in each cylinder. During this time, by controlling the control valve in the same manner as during normal operation, an appropriate amount of evaporated fuel is sucked into each cylinder, and further, the amount of fuel vapor blown from each cylinder is sufficiently suppressed. I can't.

  On the other hand, the above-described conventional apparatus controls the control valve at the time of starting the internal combustion engine in the same manner as in the normal operation without considering special characteristics at that time. In this regard, the above-described conventional apparatus cannot always provide ideal starting characteristics to the internal combustion engine.

  The present invention has been made to solve the above-described problems. When starting an internal combustion engine, purge control is performed in consideration of the particularity at the time of starting, thereby providing an ideal start characteristic for the internal combustion engine. It is an object of the present invention to provide an evaporative fuel treatment device that can be provided.

In order to achieve the above object, a first invention is an evaporated fuel processing apparatus for supplying evaporated fuel to an internal combustion engine having a plurality of cylinders,
A canister that stores evaporative fuel;
A purge passage communicating the canister to the intake port of each cylinder;
A purge control valve provided for each cylinder to control the conduction state between the intake port of each cylinder and the canister;
A cylinder discrimination signal generating means for generating a cylinder discrimination signal at a specific crank angle during operation of the internal combustion engine;
Asynchronous purge control means for opening the purge control valves of all the cylinders and executing crank angle asynchronous purge after the start of the internal combustion engine and before the cylinder discrimination signal is generated,
At the time when the cylinder discrimination signal is generated, the time until the intake stroke starts after the non-inhaled asynchronous purge gas remains in the corresponding intake port and the cylinder discrimination signal is generated is determined. Correction purge control means for executing a correction purge by opening the purge control valve for cylinders exceeding a value;
It is characterized by providing.

  According to a second aspect of the present invention, in the first aspect of the invention, the target cylinder for the correction purge is immediately after the cylinder discrimination in which the intake stroke is started following the cylinder discrimination cylinder in which the intake stroke is started simultaneously with the generation of the cylinder discrimination signal. An intake cylinder is included.

  According to a third aspect, in the first or second aspect, the correction purge target cylinder overlaps with an execution period of the crank angle asynchronous purge and ends before the crank angle asynchronous purge ends. As described above, the incomplete intake cylinder that has been performing the intake stroke is included.

  According to a fourth aspect of the present invention, in the third aspect of the invention, the correction purge control means applies a larger amount of correction purge to the incomplete intake cylinder than to other target cylinders.

According to a fifth invention, in any one of the first to fourth inventions,
Initial purge cylinder setting in which the cylinder in which the intake stroke is first performed among the cylinders in which the non-inhaled asynchronous purge gas does not remain in the corresponding intake port when the cylinder discrimination signal is generated is the crank synchronous initial purge cylinder Means,
Synchronous purge control means for performing a crank angle synchronous purge by opening the purge control valves of the individual cylinders in synchronization with the crank angle from the crank synchronous initial purge cylinder after generation of the cylinder discrimination signal;
It is characterized by providing.

According to a sixth invention, in any one of the first to fifth inventions,
The asynchronous purge control means includes
Control means for controlling the purge control valve so that the purge control valve is opened and closed a plurality of times before the cylinder discrimination signal is generated after the start of the internal combustion engine;
A setting means for setting the valve opening time in the plurality of initial times longer than the valve opening time in the second and subsequent times;
It is characterized by including.

  According to a seventh aspect of the present invention, there is provided an asynchronous purge prohibiting means for prohibiting the start of the crank angle asynchronous purge for a predetermined time after the start of the internal combustion engine in the first to sixth aspects of the invention. It is characterized by that.

An eighth invention is an evaporative fuel processing device for supplying evaporative fuel to an internal combustion engine having a plurality of cylinders,
A canister that stores evaporative fuel;
A purge passage communicating the canister to the intake port of each cylinder;
A purge control valve provided for each cylinder to control the conduction state between the intake port of each cylinder and the canister;
A cylinder discrimination signal generating means for generating a cylinder discrimination signal at a specific crank angle during operation of the internal combustion engine;
An asynchronous purge control means for opening the purge control valves of all the cylinders and executing a crank angle asynchronous purge after the start of the internal combustion engine is started and before the cylinder discrimination signal is generated,
The asynchronous purge control means includes
Control means for controlling the purge control valve so that the purge control valve is opened and closed a plurality of times before the cylinder discrimination signal is generated after the start of the internal combustion engine;
A setting means for setting the valve opening time in the plurality of initial times longer than the valve opening time in the second and subsequent times;
It is characterized by including.

The ninth invention is an evaporative fuel processing apparatus for supplying evaporative fuel to an internal combustion engine having a plurality of cylinders,
A canister that stores evaporative fuel;
A purge passage communicating the canister to the intake port of each cylinder;
A purge control valve provided for each cylinder to control the conduction state between the intake port of each cylinder and the canister;
A cylinder discrimination signal generating means for generating a cylinder discrimination signal at a specific crank angle during operation of the internal combustion engine;
Asynchronous purge control means for opening the purge control valves of all the cylinders and executing crank angle asynchronous purge after the start of the internal combustion engine and before the cylinder discrimination signal is generated,
Asynchronous purge prohibiting means for prohibiting the start of the crank angle asynchronous purge for a predetermined time after the start of the internal combustion engine,
It is characterized by providing.

  According to the first aspect, by performing the crank angle asynchronous purge before the cylinder discrimination signal is generated, the evaporated fuel can be supplied to the individual cylinders before the cylinder discrimination signal is generated. . For a cylinder that has been able to suck all of the evaporated fuel supplied by crank angle asynchronous purge into the cylinder, an appropriate amount of evaporated fuel has already been sucked into the cylinder when the cylinder discrimination signal is generated. For this reason, if such a cylinder is ignited as it is, an appropriate explosion stroke can be obtained. On the other hand, for cylinders that have not been able to suck all of the evaporated fuel by crank angle asynchronous purge, the amount of evaporated fuel in the cylinder is insufficient at the time of generation of the cylinder discrimination signal, and evaporated fuel in the corresponding intake port Remains. After that, if a long time elapses before the intake stroke starts, the remaining evaporated fuel is diluted and the amount of evaporated fuel in the cylinder does not reach an appropriate amount simply by sucking in the gas in the intake port. Will occur. According to the present invention, the correction purge can be performed for the cylinder in which such a situation occurs. Therefore, according to the present invention, an appropriate amount of evaporated fuel can be supplied to all the cylinders regardless of the environment in which the individual cylinders are placed after the internal combustion engine is started.

  According to the second aspect of the invention, the correction purge can be performed on the intake cylinder immediately after the cylinder discrimination in which the intake stroke is started following the cylinder discrimination cylinder. The cylinder discrimination signal is always issued after the start of the internal combustion engine and before the crankshaft rotates 360 ° CA. In the intake cylinder immediately after cylinder discrimination, the intake stroke is not completed in the angle range of 360 ° CA before the cylinder discrimination signal is generated. Further, for an intake cylinder immediately after cylinder discrimination, a waiting time is inevitably generated after the cylinder discrimination signal is generated and before the intake stroke of the cylinder is started. In this way, the intake cylinder immediately after cylinder discrimination always satisfies the requirements as the target cylinder for the correction purge. According to the present invention, by setting the cylinder to be subject to the correction purge at all times, it is possible to always supply an appropriate amount of evaporated fuel to the intake cylinder immediately after the cylinder discrimination when starting the internal combustion engine.

  According to the third aspect of the present invention, the incomplete intake cylinder that overlaps with the execution period of the crank angle asynchronous purge and that has executed the intake stroke so as to end before the end can be included in the correction purge target. . The incomplete intake cylinder finishes the intake stroke before the end of the crank angle asynchronous purge. For this reason, at the time of generation of the cylinder discrimination signal, the evaporated fuel by the crank angle asynchronous purge remains in the intake port of the incomplete intake cylinder. Further, since the incomplete intake cylinder is a cylinder that executes the intake stroke immediately after the internal combustion engine is started, it does not reach the intake stroke for a while after the generation of the cylinder discrimination signal. In this way, the incomplete intake cylinder always satisfies the requirements as the correction purge target cylinder. Further, for an incomplete intake cylinder, an exhaust stroke may be executed after the intake stroke for sucking the evaporated fuel by the crank angle asynchronous purge and before the intake stroke is executed again. In this case, since a part of the evaporated fuel supplied in the exhaust stroke is discharged, the supply amount of the evaporated fuel to the incomplete intake cylinder becomes further insufficient. According to the present invention, by always setting the cylinder to be subject to the correction purge, it is possible to always supply an appropriate amount of evaporated fuel to the incomplete intake cylinder when starting the internal combustion engine.

  According to the fourth aspect of the invention, a large amount of correction purge can be applied to the incomplete intake cylinder. As for the incomplete intake cylinder, fuel shortage occurs due to blow-by, so that the amount of evaporated fuel that can be supplied by the crank angle asynchronous purge is smaller than that of other target cylinders. According to the present invention, it is possible to supply an appropriate amount of evaporated fuel to all the cylinders by increasing the correction purge amount for the cylinder.

  According to the fifth aspect of the invention, the crank angle synchronization is started from the cylinder in which the intake stroke is performed earliest among the cylinders in which the evaporated fuel by the crank asynchronous purge does not remain in the intake port when the cylinder discrimination signal is generated. Purge can be started. For the cylinders in which the evaporated fuel does not remain in the intake port due to the crank angle asynchronous purge, the entire amount of the evaporated fuel required for the intake stroke can be individually supplied by the crank angle synchronous purge. For this reason, according to the present invention, appropriate fuel supply by crank angle synchronous purge can be started at the earliest possible time.

  According to the sixth or eighth invention, the crank angle asynchronous purge can be realized by repeatedly opening and closing the control valve before the generation of the cylinder discrimination signal. At this time, the first valve opening time can be set longer than the second and subsequent valve opening times. If the control valve is repeatedly opened and closed, the mixing effect in the intake passage is enhanced, thereby improving the mixing of fuel and air in an environment where the flow velocity is low. Further, if the initial valve opening time is lengthened, the evaporated fuel purge can be advanced to some extent in an environment immediately after the start in which almost no intake negative pressure is generated. For this reason, according to the present invention, the effect of improving the startability by the cranking asynchronous purge can be sufficiently enhanced.

  According to the seventh or ninth aspect, the prohibition period can be provided after the start of the internal combustion engine until the crank angle asynchronous purge is started. In the cylinder in which the intake stroke is performed immediately after the start, the gas sucked by the intake stroke is easily exhausted without being ignited. For this reason, if a crank angle asynchronous purge prohibition period is provided immediately after starting, the amount of evaporated fuel exhausted without being used as fuel is reduced. Therefore, according to the present invention, it is possible to sufficiently improve the startability of the internal combustion engine while maintaining good emission characteristics at the start.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
FIG. 1A is a diagram for explaining the mechanical configuration of the first embodiment of the present invention. FIG. 1B is a diagram for explaining the electrical configuration of the system of the present embodiment. As shown in FIG. 1A, the system of this embodiment includes an internal combustion engine 10. The internal combustion engine 10 includes a plurality of cylinders. Hereinafter, for convenience of explanation, it is assumed that the internal combustion engine 10 is a four-cylinder engine.

  The four cylinders each incorporate an intake valve 12 that opens and closes an intake port and an exhaust valve 14 that opens and closes an exhaust port. FIG. 1A shows one of these cylinders. A branch pipe of the intake manifold 16 communicates with the intake port of each cylinder. The branch pipes for four cylinders gather at one end and communicate with the surge tank 18. A throttle valve 20 for controlling the conduction state of the intake passage is disposed upstream of the surge tank 18.

  The internal combustion engine 10 includes a fuel injection valve 22 for each cylinder. The fuel injection valve 22 can inject fuel into the intake port of each cylinder. A purge passage 24 communicates with the vicinity of the intake port. The purge passage 24 is prepared for each cylinder, and each has a D-VSV 26. The D-VSV 26 is a control valve that opens and closes in response to a duty signal. According to the D-VSV 26, the conduction state of the purge passage 24 can be substantially controlled.

  The purge passages 24 for the four cylinders all communicate with the canister 28. The canister 28 incorporates activated carbon therein, and includes a vapor inflow hole 30 and an air hole 32. The vapor inflow hole 30 communicates with the fuel tank via a vapor passage (not shown). The air holes 32 communicate with the atmosphere as shown in FIG.

  Inside the fuel tank, there is a gas containing evaporated fuel. This gas flows into the canister 28 from the vapor inflow hole 30 when refueling, for example. At this time, the canister 28 adsorbs the evaporated fuel contained in the gas and causes only the air to flow out from the atmospheric hole 32. As a result, the canister 28 is in a state where the evaporated fuel is adsorbed.

  The system of this embodiment can appropriately open the D-VSV 26 of each cylinder during the operation of the internal combustion engine 10. While the internal combustion engine 10 is in operation, intake negative pressure is generated. When the D-VSV 26 is opened, the negative pressure is guided to the canister 28. As a result, a flow of air flowing in from the atmospheric hole 32 is generated inside the canister 28, and the evaporated fuel is purged by the flow of air. In the system of this embodiment, the evaporated fuel adsorbed by the canister 28 can be caused to flow into the individual cylinders in this way.

  As shown in FIG. 1B, the system of the present embodiment includes an ECU (Electronic Control Unit) 40. An ignition switch (IG) 42, a starter switch 44, a crank angle sensor 46, and a water temperature sensor 48 are connected to the ECU 40. The ECU 40 is connected to a D-VSV 26 disposed in the # 1 cylinder to the # 4 cylinder.

  The crank angle sensor 46 generates a pulse signal every time the crankshaft rotates 30 ° CA, and when the # 1 cylinder piston passes the intake top dead center, and the # 4 cylinder piston indicates the intake top dead center. When passing, a cylinder discrimination signal is generated. When the ECU 40 receives the cylinder discrimination signal indicating that the # 4 cylinder has reached the intake top dead center after the internal combustion engine 10 is started, the ECU 40 recognizes that the crank angle is 0 ° CA. When the cylinder discrimination signal indicating that the # 1 cylinder has reached the intake top dead center is received, the crank angle is recognized as 360 ° CA at that time. Hereinafter, this recognition of the crank angle is referred to as “cylinder discrimination”.

  As described above, the ECU 40 can finish the cylinder discrimination at the timing when the # 1 cylinder or the # 4 cylinder reaches the intake top dead center after the internal combustion engine 10 is started. When the cylinder discrimination is completed, the ECU 40 can continue to specify the rotational position of the crankshaft by counting the pulse signals generated every 30 ° CA thereafter.

[Operation of Embodiment 1]
Normally, the internal combustion engine 10 is started in a situation where the internal combustion engine 10 is not warmed up. Under such circumstances, since the fuel is difficult to vaporize, when the fuel is injected from the fuel injection valve 22, a situation occurs in which part of the fuel remains in a liquid state and does not contribute to combustion. On the other hand, if the fuel adsorbed by the canister 28 is purged and supplied to the internal combustion engine 10, the already vaporized fuel can be supplied, and good combustibility can be obtained even in a low temperature environment.

  For this reason, the system of the present embodiment realizes a desired fuel supply by stopping the fuel supply by the fuel injection valve 22 and purging the evaporated fuel in the canister 28 when the internal combustion engine 10 is started. . More specifically, the system according to this embodiment is configured so that, when the internal combustion engine 10 is started, the D-VSV 26 disposed for each cylinder is appropriately opened while the fuel injection valve 22 is closed, so that the individual cylinders are opened. An appropriate amount of evaporated fuel was supplied.

(Crank angle asynchronous purge and crank angle synchronous purge)
FIG. 2 is a timing chart for explaining an example of start-up purge control realized in the system of the present embodiment. More specifically, FIG. 2A shows a waveform of the engine speed NE immediately after the internal combustion engine 10 is started. FIG. 2B is a diagram for explaining the transition of the stroke in each cylinder. FIG. 2C is a diagram for explaining a purge rule used in the present embodiment.

  The ECU 40 includes a crank angle counter CCRNK in order to grasp the rotational position of the crankshaft during operation of the internal combustion engine 10. When the cylinder discrimination signal indicating that the # 4 cylinder has reached the intake top dead center is recognized after the internal combustion engine 10 is started, the crank angle counter CCRNK recognizes a value corresponding to 0 ° CA (specifically, “ 0 "). Further, when the cylinder discrimination signal indicating that the # 1 cylinder has reached the intake top dead center is issued first after the internal combustion engine 10 is started, CCRNK at that time is a value corresponding to 360 ° CA (specifically, 12).

  After the CCRNK is set to the above value, it is counted up every time a pulse signal is issued from the crank angle sensor 46 every 30 ° CA. When the crank angle reaches 720 ° CA, that is, when the # 4 cylinder reaches the intake top dead center, it is reset to zero at that time.

  The triangular waveform repeatedly drawn in FIG. 2B represents the count value of the crank angle counter CCRNK described above. That is, in the chart shown in FIG. 2B, after the starter switch 44 is turned on, the # 4 cylinder has reached the intake top dead center when the crankshaft rotates by an angle slightly smaller than 360 ° CA. This indicates that the cylinder discrimination signal indicating is generated and that the crank angle counter CCRNK repeats increasing and resetting in accordance with the rotation of the crankshaft thereafter.

  The system of this embodiment can detect the state of each cylinder based on the count value of the crank angle counter CCRNK after the cylinder discrimination is completed. For this reason, after the cylinder discrimination is completed, the evaporative fuel can be supplied to all the cylinders at appropriate timings by opening and closing the D-VSV 26 of each cylinder in synchronization with the crank angle. is there. Hereinafter, such a fuel supply method is referred to as “crank angle synchronous purge”.

  However, the crank angle synchronous purge cannot be started until the cylinder discrimination is completed. On the other hand, if the fuel supply is started after the completion of the cylinder discrimination, the timing of the first explosion is delayed, and it becomes difficult to give the internal combustion engine 10 good start response. That is, when fuel is supplied by fuel injection, the supply ends instantaneously, so that even if the fuel supply is started after the end of cylinder discrimination, there is no significant delay in the timing of the initial explosion. On the other hand, when fuel is supplied by evaporative fuel purging, it takes a long time to supply the fuel. It is easy to generate a delay that cannot be ignored.

  Therefore, in the system of the present embodiment, when the internal combustion engine 10 is started, the crank angle asynchronous purge is executed for all the cylinders without waiting for the generation of the cylinder discrimination signal.

  The white arrow shown in FIG. 2C indicates the period during which the D-VSV 26 of each cylinder is opened, that is, the purge fuel is supplied to the intake port of each cylinder in the system of this embodiment. Indicates the period of inhalation. In particular, among the white arrows, those continuing for a predetermined period immediately after the starter is turned on indicate a purge period corresponding to the crank angle asynchronous purge described above. As shown in this figure, in the system of this embodiment, after the starter switch is turned ON, the D-VSVs 26 of all the cylinders are opened equally for a predetermined time. At this time, the D-VSV 26 is opened and closed regardless of the crank angle. Here, the open / close control of the D-VSV 26 by such a method is referred to as “crank angle asynchronous purge”.

  Areas indicated by hatching in FIGS. 2B and 2C indicate periods in which the intake stroke is executed in individual cylinders. In the system of this embodiment, a cylinder discrimination signal is issued when the # 4 cylinder or the # 1 cylinder passes through the intake top dead center. For this reason, if a cylinder discrimination signal corresponding to the # 4 cylinder is first generated after the starter is turned on, the internal combustion engine 10 is stopped with the # 1 cylinder passing the intake top dead center. It is thought.

  The charts shown in FIGS. 2B and 2C particularly illustrate the case where the internal combustion engine 10 is stopped at a position where the # 1 cylinder slightly exceeds the intake top dead center. Therefore, according to these charts, the intake stroke of the # 1 cylinder is started at the same time when the starter is turned on, and then the intake stroke of the # 3 cylinder is started when the crank angle is changed by about 180 ° CA. . When the rotation of 180 ° CA further occurs, the # 4 cylinder reaches the intake top dead center, and as a result, a cylinder discrimination signal is generated.

  The execution period of the crank angle asynchronous purge is set as a period for supplying an evaporated fuel amount suitable for starting to each cylinder before cylinder discrimination. In this execution period, in the system of the present embodiment, as shown in FIG. 2C, an intake stroke that is performed immediately before the cylinder determination signal is generated, more specifically, immediately before the cylinder determination signal is generated. The process ends halfway (middle of the intake stroke of the # 3 cylinder in FIG. 2).

  Therefore, according to the operation shown in FIG. 2, after the starter is turned on, in the # 1 cylinder, only the evaporated fuel purged in the first half of the crank angle asynchronous purge is sucked into the cylinder and purged in the second half. The evaporated fuel is retained in the intake port. In the # 3 cylinder, almost all the evaporated fuel supplied by crank angle asynchronous purge is sucked into the cylinder. In the # 4 cylinder and the # 2 cylinder, all of the evaporated fuel supplied by the crank angle asynchronous purge is held in the intake port without being sucked into the cylinder until at least the time of cylinder discrimination.

  That is, according to the system of the present embodiment, when the cylinder discrimination signal is generated by performing the crank angle asynchronous purge, the cylinder that has been performing the intake stroke immediately before that (# 3 cylinder here; Appropriate fuel supply to the intake cylinder immediately before cylinder discrimination ”can be terminated. The intake cylinder immediately before cylinder discrimination reaches compression top dead center at the time when rotation of 180 ° CA occurs after completion of cylinder discrimination. At this time, it is possible to execute an ignition process. For this reason, according to the system of the present embodiment, it is possible to obtain the first explosion at the time of 180 ° CA after completion of the cylinder discrimination.

  The # 4 cylinder in FIG. 2 starts the intake stroke simultaneously with the generation of the cylinder discrimination signal. Hereinafter, such a cylinder is referred to as a “cylinder discrimination cylinder”. In other words, the cylinder discrimination cylinder starts the first intake stroke immediately after the end of the crank angle asynchronous purge. The evaporated fuel purged to the intake port of the cylinder discrimination cylinder is diluted with the passage of time, but if the elapsed time is small, the dilution can be ignored. Therefore, the cylinder discriminating cylinder can suck almost all of the evaporated fuel supplied by the crank angle asynchronous purge by the first intake stroke.

  That is, the system of the present embodiment can perform appropriate fuel supply to the cylinder discrimination cylinder by performing crank angle asynchronous purge. According to the example shown in FIG. 2, the cylinder discrimination cylinder (# 4 cylinder) reaches the compression top dead center at 360 ° CA after the cylinder discrimination, that is, when the explosion stroke of the # 3 cylinder is completed. Therefore, according to the system of the present embodiment, it is possible to cause an appropriate explosion in the cylinder discrimination cylinder following the intake cylinder immediately before cylinder discrimination.

  The # 2 cylinder in FIG. 2 performs an intake stroke following the cylinder discrimination cylinder. Hereinafter, such a cylinder is referred to as an “intake cylinder immediately after cylinder discrimination”. In other words, in the intake cylinder immediately after cylinder discrimination, after the cylinder discrimination signal is generated, the intake stroke is not started until rotation of 180 ° CA occurs. As for the intake cylinder immediately after the cylinder discrimination, the evaporated fuel by the crank angle asynchronous purge is held in the corresponding intake port in the non-intake state. However, the concentration of the evaporated fuel is diluted during the period from the end of the crank angle asynchronous purge to the start of intake in the intake cylinder immediately after cylinder discrimination. For this reason, with respect to the intake cylinder immediately after the cylinder discrimination, a sufficient amount of fuel cannot be sucked into the cylinder by the first intake stroke only by sucking the evaporated fuel supplied by the crank angle asynchronous purge.

  Therefore, in the system according to the present embodiment, for the intake cylinder immediately after the cylinder discrimination, the correction purge for compensating for the diluted amount of the evaporated fuel is performed prior to the first intake stroke in the cylinder. In FIG. 2 (C), the white arrow indicated by reference numeral 50 in the column of the # 2 cylinder corresponds to the purge period corresponding to the correction purge. The ECU 40 can identify which cylinder is the intake cylinder immediately after the cylinder discrimination at the same time as receiving the cylinder discrimination signal. The ECU 40 simultaneously opens the D-VSV 26 of the intake cylinder immediately after the cylinder discrimination for a predetermined correction purge period.

  When the above processing is executed, an appropriate amount of evaporated fuel suitable for starting can be sucked into the cylinder in the intake cylinder immediately after cylinder discrimination, that is, the # 2 cylinder in FIG. 2 by the first intake stroke. For this reason, according to the system of the present embodiment, it is possible to cause an appropriate explosion in the intake cylinder immediately after cylinder discrimination after the cylinder discrimination cylinder.

  The # 1 cylinder in FIG. 2 has reached compression top dead center when the cylinder discrimination signal is generated. At this time, a slight amount of evaporated fuel purged in the initial stage of the crank angle asynchronous purge is sucked into the cylinder of the # 1 cylinder. Since sufficient combustion cannot be obtained with the fuel, an expansion stroke without explosion is performed here. Hereinafter, a cylinder that incompletely sucks a part of the evaporated fuel by crank angle asynchronous purge, such as the above-described # 1 cylinder, is referred to as an “incomplete intake cylinder”.

  In the incomplete intake cylinder (# 1 cylinder), the exhaust stroke is performed following the above-described expansion stroke. As a result, the evaporated fuel sucked into the cylinder at the end of cylinder discrimination is discharged to the exhaust system without being used for combustion. After the cylinder discrimination, when a change of about 360 ° CA occurs, the second intake stroke in the incomplete intake cylinder is started, and the evaporated fuel held in the intake port by the intake stroke Inhaled.

  As explained above, for the incomplete intake cylinder, a part of the evaporated fuel by the crank angle asynchronous purge is exhausted. Therefore, when the crank angle asynchronous purge is completed, it is already necessary for one explosion stroke. Evaporative fuel is not present. Further, for the incomplete intake cylinder, since the period until the next intake stroke is started after the crank angle asynchronous purge is completed, dilution of the evaporated fuel remaining in the intake port proceeds greatly. For this reason, for the incomplete intake cylinder, sufficient evaporated fuel cannot be supplied into the cylinder by the crank angle asynchronous purge more than the intake cylinder immediately after the cylinder discrimination.

  Therefore, the system of the present embodiment performs a correction purge for the incomplete intake cylinder before the first intake stroke after the cylinder determination is started to compensate for the diluted and exhausted fuel vapor. It was decided. A white arrow indicated by reference numeral 52 in the column of the # 1 cylinder in FIG. 2C indicates a purge period corresponding to the correction purge. The ECU 40 can identify which cylinder is the incomplete intake cylinder simultaneously with receiving the cylinder discrimination signal. The ECU 40 simultaneously opens the D-VSV 26 of the incomplete intake cylinder for a predetermined correction purge period.

  When the above processing is executed, even in the incomplete intake cylinder, that is, the # 1 cylinder in FIG. 2, an appropriate amount of evaporated fuel suitable for starting is sucked into the cylinder in the intake stroke that is performed for the first time after cylinder discrimination. Can do. For this reason, according to the system of the present embodiment, it is possible to cause an appropriate explosion even in the incomplete intake cylinder immediately after the cylinder discrimination.

  As described above, according to the system of the present embodiment, it is possible to cause explosions to be appropriately and sequentially generated in each of the four cylinders immediately after the cylinder discrimination signal is generated. For this reason, according to the system of the present embodiment, it is possible to achieve excellent start-up responsiveness while using evaporated fuel as the start-up fuel.

  By the way, in the system of the present embodiment, when the intake cylinder (# 3 cylinder) immediately before cylinder discrimination finishes the intake stroke for the first explosion, all the evaporated fuel in the intake port of the cylinder is sucked into the cylinder. Yes. Similar circumstances apply for all other cylinders. That is, for the cylinder discrimination cylinder (# 4 cylinder), when the first intake stroke is completed, all the evaporated fuel in the intake port of the cylinder is sucked into the cylinder. In the intake cylinder (# 2 cylinder) immediately after cylinder discrimination, when the first intake stroke is completed, and in the incomplete intake cylinder (# 1 cylinder), when the first intake stroke is performed after cylinder discrimination. A similar state is formed. For this reason, in the system of the present embodiment, it is possible to supply fuel to each cylinder without considering the influence of crank angle asynchronous injection after each of the intake strokes described above.

  The white arrows indicated by reference numerals 54 to 62 in FIG. 2C respectively correspond to the crank angle synchronous purge period executed in the present embodiment after completion of cylinder discrimination. . All of them are set to timings that are not affected by the crank angle asynchronous purge. In addition, the individual crank angle synchronous purge period is set as a period during which the fuel vapor amount suitable for starting can be purged under each negative pressure environment. For this reason, according to the system of the present embodiment, after starting the cylinder discrimination, smooth startability can be realized by supplying the evaporated fuel to each cylinder by crank angle synchronous purge.

[Specific Processing in Embodiment 1]
Hereinafter, with reference to FIG. 3 to FIG. 6, the contents of specific processing executed by the ECU 40 in the present embodiment in order to realize the above functions will be described.
FIG. 3 is a flowchart of a main routine executed by the ECU 40 to realize the above functions. This routine is repeatedly started at predetermined time intervals while the ignition switch (IG) of the vehicle is turned on.

  When the routine shown in FIG. 3 is started, it is first determined whether or not the start purge condition is satisfied (step 100). The start purge condition is a condition that is satisfied under a situation in which the internal combustion engine 10 is to be started by the evaporated fuel captured by the canister 28. Specifically, this condition is recognized when the internal combustion engine 10 is cold-started in a state where a sufficient amount of evaporated fuel is adsorbed by the canister 28.

  If it is confirmed that the starting purge condition is satisfied, it is next determined whether or not the count value of the crank angle counter CCRNK is −1 or less (step 102). As described above, the crank angle counter CCRNK is set to a value corresponding to 0 ° CA (0) or a value corresponding to 360 ° CA (12) when the cylinder discrimination signal is generated. The count value CCRNK is maintained at −1 until generation of a cylinder discrimination signal is recognized. For this reason, the processing of this step 102 is equivalent to determining whether or not a cylinder discrimination signal has not been generated.

  After the starter is turned ON, until the cylinder discrimination signal is generated, in step 102, the establishment of CCRNK ≦ −1 is recognized. In this case, the crank angle asynchronous purge execution time TPGST is then calculated (step 104). As shown in the frame of step 104, the ECU 40 stores a map that defines the execution time TPGST of the asynchronous purge in relation to the cooling water temperature THW. This map is determined such that the asynchronous purge execution time TPGST becomes longer as the coolant temperature THW is lower.

  The friction of the internal combustion engine 10 increases as the cooling water temperature THW decreases. For this reason, the internal combustion engine 10 becomes difficult to start as the coolant temperature THW is lower. Further, in the internal combustion engine 10, control is performed such that the ISC opening is increased and the amount of idle air is increased as the coolant temperature THW is lower. Then, as the amount of idle air increases, the intake pipe pressure MV at the time of start-up becomes difficult to be negative, and as a result, the purge of evaporated fuel is less likely to occur.

  According to the process in step 104, the lower the coolant temperature THW, the longer the crank angle asynchronous purge execution time TPGST can be created, and the situation in which the evaporated fuel is more easily purged can be created. For this reason, according to the system of the present embodiment, the asynchronous purge execution time TPGST can be appropriately set so that an appropriate amount of evaporated fuel is always purged regardless of the coolant temperature THW at the time of starting.

  Next, in the routine shown in FIG. 3, the D-VSVs 26 of the # 1 to # 4 cylinders are simultaneously opened (step 106). Apart from this routine, the ECU 40 executes a process of closing all the D-VSVs 26 when the execution time TPGST has elapsed. According to these processes, the crank angle asynchronous purge can be started immediately after the start purge condition is established, and thereafter the crank angle asynchronous purge can be terminated when the execution time TPGST has elapsed.

  When the cylinder discrimination signal is generated after the internal combustion engine 10 is started, 0 or 12 is set in the crank angle counter CCRNK. After this setting, in step 102, it is determined that CCRNK ≦ −1 is not satisfied. In this case, execution of start purge control, that is, control for crank angle synchronous purge is commanded (step 108). When this process is executed, control of crank angle synchronous purge described later is started.

  When a further time elapses after the crank angle synchronous purge is started, the internal combustion engine 10 is sufficiently warmed up and the necessity for the start purge disappears. When this necessity disappears, the establishment of the start purge condition is denied in step 100, and the start of normal fuel injection control is commanded (step 110). After this process is executed, normal operation control using the fuel injection valve 22 is started thereafter.

  FIG. 4 is a flowchart for explaining details of processing executed by the ECU 40 in order to realize crank angle synchronous purge. This routine is repeatedly started every time a pulse signal is issued from the crank angle sensor 46, that is, every time the crankshaft rotates 30 ° CA.

  When the routine shown in FIG. 4 is started, it is first determined whether or not the # 4 cylinder has reached the intake top dead center (step 120). If the cylinder discrimination signal corresponding to the # 4 cylinder has been issued in the current processing cycle, the discrimination in this step 120 is affirmed. In this case, the crank angle counter CCRNK is set to 0 (step 122), and then 1 is set to the cylinder discrimination flag FTDC (step 124).

  On the other hand, if it is determined in step 120 that the # 4 cylinder has not reached the intake top dead center, it is then determined whether the # 1 cylinder has reached the intake top dead center (step 126). ). Specifically, it is determined here whether or not a cylinder determination signal corresponding to the # 1 cylinder has been generated. As a result, if the above determination is affirmed, 12 is set in the crank angle counter CCRNK (step 127), and then the processing of step 124 is executed.

  If it is determined in step 126 that the # 1 cylinder has not reached the intake top dead center, it is next determined whether 1 is set in the cylinder discrimination flag FTDC (step 128). The cylinder discrimination flag FTDC is set to 0 by the initial process when the internal combustion engine 10 is started. For this reason, after the internal combustion engine 10 is started, 0 is set in FTDC while the cylinder discrimination signal has not yet been generated. In this case, the determination in step 128 is denied, -1 is set in the crank angle counter CCRNK (step 130), and then the number of intakes is cleared (step 132), and then the current processing cycle is terminated. .

  On the other hand, when this routine is started after the cylinder discrimination is completed, it is recognized in step 128 that FTDC = 1. In this case, the crank angle counter CCRNK is incremented (step 134).

  In the routine shown in FIG. 4, following the process of step 124 or the process of step 134, the current crank angle coincides with the intake timing of any cylinder. It is determined whether or not the angle reaches the top dead center (step 136).

  Specifically, the ECU 40 affirms the determination of “intake timing” when the crank angle counter CCRNK matches any one of 0, 6, 12, and 18. For example, this determination is affirmed when the cylinder discrimination signal is first issued (CCRNK = 0 or 12). If this determination is affirmed, the cylinder number of the intake cylinder is then calculated (step 138). The ECU 40 stores the value of the crank angle counter CCRNK corresponding to the intake top dead center for each cylinder. Here, as shown in the frame of step 138, the intake cylinder number corresponding to the current CCRNK is calculated according to the storage.

  Next, the intake frequency counter is incremented (step 140). The intake number counter is a counter for counting the number of intakes that occurred after cylinder discrimination, and is set to 0 by the initial process when the internal combustion engine 10 is started. Therefore, the intake number counter is set to 1 when the first intake timing is recognized, that is, when the first cylinder discrimination signal corresponding to the # 4 or # 1 cylinder is generated.

  In the routine shown in FIG. 4, it is next determined whether or not the current intake timing is the first timing (step 142). Specifically, it is determined whether or not the intake air number counter is 1. As a result, when it is determined that it is the first intake timing, a preparation for starting the crank angle synchronous purge and a series of processes for realizing the correction purge described above are executed.

  Here, first, a map number to be used in the current start purge is set (step 144). As with the crank angle asynchronous purge execution time TPGST, it is appropriate that the crank angle synchronous purge execution time TPG to be set for each cylinder is longer as the cooling water temperature THW is lower. For this reason, the ECU 40 stores a plurality of maps for determining the synchronous purge execution time TPG using the cooling water temperature THW as a parameter. Further, as shown in the frame of step 144, the ECU 40 stores a number setting map that defines the relationship between a specific cooling water temperature region and a map number adapted in the region. In step 144, the map number matching the current cooling water temperature THW is read according to the number setting map.

  Next, a setting map for the purge time TPG is selected (step 146). The ECU 40 stores a map in which the crank angle synchronous purge execution time TPG is determined in relation to the number of executions of the synchronous purge. A plurality of maps are prepared using the cooling water temperature THW as a parameter. In step 146, the map numbered in step 144 is selected from those maps as the map to be used in the current start purge. The map shown in the frame of step 146 is the map selected by the above processing.

  In the system of this embodiment, as shown in FIG. 2C, the first crank angle synchronous purge 54 is executed for the intake cylinder (# 3 cylinder) immediately before cylinder discrimination, and then the other cylinders are sequentially executed. Crank angle synchronous purges 56, 58, 60... Are executed. The engine speed NE starts to rise at the same time as the execution time of the first crank angle synchronization purge 54, and then increases to correspond to the number of executions of the crank angle synchronization purge. Further, the intake pipe pressure MV becomes negative in accordance with the rise of the engine speed NE. As the intake pipe pressure MV becomes negative, the purge flow rate per unit time increases. For this reason, it is appropriate that the crank angle synchronous purge execution time TPG is gradually shortened as the number of purges increases.

  The execution time TPG map used in the present embodiment is set in relation to “the number of purges + 1” as shown in the frame of step 146. Here, “the number of purges” means the number of crank angle synchronous purges already performed. Therefore, “the number of purges + 1” is, for example, “1” at the timing when the first crank angle synchronization purge is to be executed, “2” at the timing when the second crank angle synchronization purge is to be executed, and the Nth crank angle synchronization. It becomes “N” at the timing when the purge should be executed.

  According to the above map, the execution time TPG decreases as the “purge number + 1” increases, and eventually converges to the minimum value. For this reason, according to the above map, the execution time TPG can always be appropriately set in the process in which the negative pressure of the intake pipe pressure MV advances as the engine speed NE rises.

  Next, in the routine shown in FIG. 4, a setting map for the purge advance amount CRNKPG is selected (step 148). In the system of the present embodiment, the crank angle CRNKPGS for starting the crank angle synchronous purge in each cylinder is set to an angle advanced by the purge advance amount CRNKPG from the crank angle at which the intake stroke is started in that cylinder. I am going to do that. As in the case of the execution time TPG, the ECU 40 stores a plurality of maps in which the coolant advancement amount CRNKPG is set with the cooling water temperature THW as a parameter. In step 148, the map numbered in step 144 is selected from those maps as a map to be used in the current start purge. The map shown in the frame of step 148 is the map selected by the above processing.

  As described above, the purge time TPG of the crank angle synchronous purge is shortened as the number of purge executions increases. The crank angle synchronous purge needs to be finished before the intake stroke in the corresponding cylinder is finished. Therefore, if the purge execution time TPG is long, the purge advance amount CRNKPG needs to be increased.

  The map of the purge advance amount CRNKPG used in the present embodiment is set so that the purge advance amount CRNKPG decreases as the “purge number + 1” increases, as in the map of the execution time TPG. For this reason, according to the above map, it is possible to set an appropriate purge advance amount CRNKPG corresponding to the length of the execution time TPG.

  In the routine shown in FIG. 4, next, the starting cylinder STPG for crank angle synchronous purge is set (step 150). Here, the cylinder that starts the intake stroke with a delay of three strokes from the cylinder at the intake top dead center at the present time (that is, at the time of cylinder discrimination), that is, the cylinder that was performing the intake stroke immediately before the occurrence of the cylinder discrimination signal is purged The starting cylinder is STPG. Specifically, when the # 4 cylinder is currently at the intake top dead center, the # 3 cylinder, and when the # 1 cylinder is currently at the intake top dead center, the # 2 cylinder is the start cylinder STPG. Is done.

  The start cylinder STPG set by the above processing is a cylinder in which the influence of the crank angle asynchronous purge has already been eliminated from the intake port when the cylinder discrimination signal is generated. If the crank angle synchronous purge is started from this cylinder, the crank angle synchronous purge can be executed in all cylinders while avoiding interference with the crank angle asynchronous purge.

  In addition to the present routine, the ECU 40 executes a routine for opening and closing the D-VSV 26 in synchronization with the crank angle (details will be described later with reference to FIG. 5). The ECU 40 can start the crank angle synchronous purge from the start cylinder STPG by executing the routine.

  Next, in the routine shown in FIG. 4, a correction purge is executed for the cylinders that are insufficiently purged (step 152). That is, the correction purge is executed for the intake cylinder (# 2 in FIG. 2) and the incomplete intake cylinder (# 1 in FIG. 2) immediately after the cylinder discrimination.

  FIG. 5 is a flowchart for explaining the contents of a series of processes executed in step 152. As shown in FIG. 5, first, it is determined whether or not the current value of the crank angle counter CCRNK is 0 (step 160). If the establishment of CCRNK = 0 is recognized, it can be determined that the # 4 cylinder is the cylinder discrimination cylinder. In this case, it can be further determined that # 2 cylinder is an intake cylinder immediately after cylinder discrimination, and # 1 cylinder is an incomplete intake cylinder.

  If the above determination is made, next, a corrected purge time # 2T for the # 2 cylinder (intake cylinder immediately after cylinder discrimination) is calculated (step 162). As shown in the frame of step 162, the ECU 40 stores a map that defines the corrected purge time # 2T in relation to the cylinder discrimination time. According to this map, the corrected purge time # 2T is set to a longer time as the cylinder discrimination time, that is, the time required for cylinder discrimination is shorter.

  When the cylinder discrimination time is short, it can be estimated that the cylinder discrimination is completed when the crankshaft slightly moves after the starter is turned on. In this case, it is predicted that the intake pipe pressure MV is maintained at a value near atmospheric pressure at the end of cylinder discrimination. That is, in this case, it can be determined that there is a high possibility that the supply amount of the evaporated fuel by the crank angle asynchronous purge is insufficient. According to the process of step 162, the correction purge time # 2T can be extended in such a case. For this reason, according to the system of the present embodiment, the shortage of the evaporated fuel amount due to the crank angle asynchronous purge can be appropriately compensated by the correction purge.

  When the above processing is completed, the ECU 40 executes output processing for the D-VSV 26 of the # 2 cylinder (step 164). Here, specifically, a signal requesting opening of the corrected purge time # 2T is supplied to the D-VSV 26 of the # 2 cylinder. As a result, a correction purge that compensates for the shortage of evaporated fuel is realized in the # 2 cylinder.

  In the routine shown in FIG. 5, next, a corrected purge time # 1T for the # 1 cylinder (incomplete intake cylinder) is calculated (step 166). As shown in the frame of step 166, the ECU 40 stores a map that defines the corrected purge time # 1T in relation to the cylinder discrimination time. According to this map, the corrected purge time # 1T is set to a longer time as the cylinder discrimination time is shorter for the same reason as that for setting the corrected purge time # 2T.

  As for the incomplete intake cylinder, since a part of the evaporated fuel by the crank angle asynchronous purge is discharged to the exhaust system, as described above, more correction purges are required as compared with the intake cylinder immediately after the cylinder discrimination. In response to this request, the map of the corrected purge time # 1T is shifted in the long-term direction as a whole as compared with the map of the corrected purge time # 2T. For this reason, according to the process of step 166, an appropriate correction purge can be performed on the incomplete intake cylinder.

  When the above processing is completed, the ECU 40 executes output processing for the D-VSV 26 of the # 1 cylinder (step 168). Here, specifically, a signal requesting opening of the corrected purge time # 1T is supplied to the D-VSV 26 of the # 1 cylinder. As a result, a correction purge that compensates for the shortage of evaporated fuel is realized in the # 1 cylinder.

  In the routine shown in FIG. 5, if it is determined in step 160 that CCRNK = 0 is not satisfied, it can be determined that the # 1 cylinder is the cylinder discrimination cylinder. In this case, it can be further determined that # 3 cylinder is an intake cylinder immediately after cylinder discrimination, and # 4 cylinder is an incomplete intake cylinder.

  If the above determination is made, the same processes as those in steps 162 to 168 described above are executed for the # 3 cylinder (intake cylinder immediately after cylinder discrimination) and the # 4 cylinder (steps 170 to 176). ). As a result, in each of the # 3 cylinder and the # 4 cylinder, an appropriate correction purge that compensates for the shortage of evaporated fuel is realized.

  The processes in steps 138 to 152 (see FIG. 4) and the processes in steps 160 to 176 (see FIG. 5) are executed as a series of processes when the cylinder discrimination signal is generated for the first time after the internal combustion engine 10 is started. The When the crank angle sensor 46 generates a pulse signal after the next time, the condition of step 136 or the condition of step 142 is negated in the routine shown in FIG.

  When the condition of step 136 or step 142 is negative, the purge amount (crank angle synchronous purge execution time TPG) and the purge start timing (start crank angle CRNKPGS) are set (step 180). ). Specifically, first, the execution time TPG to be applied to the next crank angle synchronous purge is calculated based on the map selected in step 146 and the number of executed purges at the current time. Next, the purge advance amount CRNKPG to be applied to the next crank angle synchronous purge is calculated based on the map selected in step 148 and the number of purges that have been executed at the present time.

  When the above processing is completed, the next crank angle synchronous purge start crank angle CRNKPGS is set (step 182). Here, first, the intake crank angle (intake CRNK) of the cylinder to be purged is read. Next, a value obtained by advancing the intake CRNK by the purge advance amount CRNKPG is set as the purge start crank angle CRNKPGS.

Next, the contents of specific processing executed by the ECU 40 to realize crank angle synchronous purge, that is, to actually open and close the D-VSV 26 will be described.
FIG. 6 is a flowchart of a routine executed by the ECU 40 for the above purpose. The routine shown in FIG. 6 is started every time the crank angle sensor 46 generates a pulse signal. When this routine is started, first, it is determined whether or not the count value of the crank angle counter CCRNK coincides with the purge start crank angle CRNKPGS (step 190).

  As a result, when CCRNK = CRNKPGS is not established, it is determined that the start of crank angle synchronous purge is not requested, and the current processing cycle is immediately terminated. On the other hand, when the establishment of CCRNK = CRNKPGS is recognized, the process for executing the crank angle synchronous purge is advanced.

  Here, first, the number of executions of crank angle synchronous purge is incremented (step 192). Next, it is determined whether the current synchronous purge is the first synchronous purge or, specifically, whether the number of executions of the synchronous purge is “1” (step 194).

  When it is determined that the current purge is the first synchronous purge, the purge target is the start cylinder STPG set in step 150 (step 196). Next, the D-VSV 26 of the starting cylinder STPG is opened (step 198). Thereafter, the ECU 40 closes the D-VSV 26 when the execution time TPG set by the processing of step 180 has elapsed. According to the above processing, in the start cylinder STPG, the crank angle synchronous purge is executed over the execution time TPG from the purge start crank angle CRNKPGS.

  According to the processing of steps 180 and 182 described above (see FIG. 4), every time the crank angle synchronous purge is executed, the purge execution time TPG and the start crank angle CRNKPGS are rewritten to the values to be applied to the next purge. It is done. When the count value of the crank angle counter CCRNK coincides with the newly rewritten start crank angle CRNKPGS, the condition of step 190 shown in FIG. 6 is satisfied, and the processing after step 192 is executed again.

  This time, since the condition of step 194 is not satisfied, the process of step 200 is executed following the process. Here, a cylinder delayed by one stroke with respect to the currently stored purge cylinder is set as a new purge target. Thereafter, the process of step 198 is executed for the D-VSV 26 of the cylinder newly targeted for purging. By repeatedly executing the above processing, the crank angle synchronization purge is executed appropriately in each cylinder. As a result, according to the system of the present embodiment, the internal combustion engine 10 can be started extremely well.

  In the first embodiment described above, the D-VSV 26 corresponds to the “purge control valve” in the first invention, and the crank angle sensor 46 corresponds to the “cylinder discrimination signal generating means” in the first invention. ing. Further, here, the ECU 40 executes the process of step 106, so that the “asynchronous purge control means” in the first invention executes the processes of steps 160 to 176, thereby correcting the “correction” in the first invention. "Purge control means" is realized respectively.

  In the first embodiment described above, the ECU 40 executes the process of step 150, whereby the “initial purge cylinder setting means” in the fifth aspect of the invention is the steps 180 and 182, and steps 190 to 198. By executing the processing, the “synchronous purge control means” in the fifth aspect of the present invention is realized.

Embodiment 2. FIG.
[Features of Embodiment 2]
Next, a second embodiment of the present invention will be described with reference to FIGS. The system of the present embodiment can be realized by causing the ECU 40 to execute a series of processes shown in FIG. 8 described later in place of steps 104 and 106 shown in FIG. 3 in the system of the first embodiment.

  FIG. 7 is a timing chart for explaining the operation of the system of this embodiment. The timing chart shown in FIG. 7 is the same as the timing chart shown in FIG. 2 except that the white arrow corresponding to the crank angle asynchronous purge is drawn intermittently.

  In the first embodiment described above, after the start of the internal combustion engine 10, the crank angle asynchronous purge is continuously executed over the execution time TPGST. That is, the D-VSV 26 is continuously opened over the execution time TPGST. In this case, the flow of the purge gas flowing into the intake port becomes stable, and the evaporated fuel is not necessarily mixed well with the intake air.

  On the other hand, if the crank angle asynchronous purge is intermittently performed, the purge gas flow is disturbed, and the mixing of the evaporated fuel and the intake air can be promoted. For the above reason, the system of the present embodiment intermittently advances the crank angle asynchronous purge as shown in FIG. 7C.

[Specific Processing in Second Embodiment]
FIG. 8 is a flowchart of a routine executed by the ECU 40 in the present embodiment in order to realize the above function. This routine is started at the same time when the starter is turned on, and thereafter repeatedly started at predetermined time intervals.

  When the routine shown in FIG. 8 is started, the cycle counter TSYUK is first incremented (step 210). Next, it is determined whether TSYUK is equal to or greater than the cycle determination value KSYUK (step 212).

  As described above, the system of this embodiment advances the crank angle asynchronous purge by intermittently opening the D-VSV 26. The period determination value KSYUK is a value corresponding to one period of time for opening and closing the D-VSV 26 at that time. On the other hand, the maximum value (value greater than or equal to KSYUK) is set in the cycle counter TSYUK by the initial process. Therefore, when the process of step 212 is executed for the first time after the internal combustion engine 10 is started, it is recognized that TSYUK ≧ KSYUK.

  When the establishment of TSYUK ≧ KSYUK is recognized, it is determined that the start time of a new driving cycle of the D-VSV 26 has arrived. In this case, first, the cycle counter TSYUK is reset to 0 (step 214), and then the number of asynchronous purge executions CPGST is incremented (step 216). The value of CPGST is set to 0 by the initial process. For this reason, the value CPGST matches the number of asynchronous purges that have actually been executed after the starter is turned on.

  In the routine shown in FIG. 8, it is then determined whether the number of asynchronous purge executions CPGST is equal to or greater than the number of guards KCST (step 218). The guard count KCST is a guard value imposed on the number of executions of the crank angle asynchronous purge. If it is determined that the number of executions CPGST is equal to or greater than the number of guards KCST, this routine is immediately terminated without opening the D-VSV 26 in order to avoid excessive purge.

  On the other hand, if it is determined that the execution count CPGST is smaller than the guard count KCST, it is further determined whether the integrated purge time TSPGST is equal to or longer than the guard time KTST (step 220). The accumulated purge time TSPGST is a value obtained by integrating the periods during which crank angle asynchronous purge has been executed since the start of the internal combustion engine. On the other hand, the guard time KTST is a guard value imposed on the execution time of the crank angle asynchronous purge. When it is determined that the accumulated time TSPGST is equal to or longer than the guard time KTST, this routine is immediately terminated thereafter in order to avoid excessive purge.

  If it is determined that the accumulated purge time TSPGST has not yet reached the guard time KTST, the D-VSVs 26 of the # 1 to # 4 cylinders are simultaneously opened (step 222). Apart from this routine, the ECU 40 executes a process of closing all the D-VSVs 26 when the execution time TPGST has elapsed. In the present embodiment, the execution time TPGST is set to an appropriate value shorter than the cycle determination value KSYUK. Therefore, according to the above processing, all the D-VSVs 26 can be opened and closed only once during the KSYUK period.

  When the above processing is completed, the cumulative purge TSPGST is updated by adding the execution time TPGST to the current cumulative purge time TSPGST (step 224). According to the above processing, each time the crank angle asynchronous purge is executed, the value can be appropriately updated by extending the integrated purge time TSPGST by the execution time TPGST.

  After the processes in steps 222 and 224 are executed, until the time corresponding to the cycle determination value KSYUK has elapsed, it is determined in step 212 that the condition is not satisfied each time the routine shown in FIG. 8 is started. In this case, the current process is terminated without any further process. Then, when the time corresponding to the cycle determination value KSYUK has elapsed, the processing after step 218 is repeated again.

  As a result, according to the system of the present embodiment, the crank angle synchronous purge can be intermittently advanced until the number of purges reaches the guard number KCST or until the accumulated purge time reaches the guard time KTST.

  The series of processes shown in FIG. 8 can be executed with the period determination value KSYUK, the execution time TPGST, and the like as constant values. However, if these values are appropriately changed in accordance with the state of the internal combustion engine 10, the control accuracy of the crank angle asynchronous purge can be further increased.

  FIG. 9 is a flowchart of a routine executed by the ECU 40 in the present embodiment from the above viewpoint. This routine is executed only once immediately after the internal combustion engine 10 is started, prior to the start of the routine shown in FIG.

  In the routine shown in FIG. 9, first, the cycle determination value KSYUK is calculated (step 230). As shown in the frame of step 230, the ECU 40 stores a map that defines the cycle determination value KSYUK in relation to the coolant temperature THW. Here, the period determination value KSYUK is set according to this map. According to this map, the cycle determination value KSYUK is set to a larger value as the cooling water temperature THW is lower. In the internal combustion engine 10, the ISC opening increases as the temperature decreases, and as a result, intake negative pressure is less likely to occur. In order to stably purge the evaporated fuel in an environment in which the intake pipe pressure MV is difficult to be negative, it is desirable that the crank angle asynchronous purge period is large. According to the processing of step 230, the cycle determination value KSYUK can be set so as to meet the request. For this reason, according to the system of the present embodiment, the evaporated fuel can be always stably supplied to the internal combustion engine without being affected by the temperature environment at the start.

  In the routine shown in FIG. 9, next, the guard count KCST is calculated (step 232). As shown in the frame of step 232, the ECU 40 stores a map that defines the guard count KCST in relation to the cooling water temperature THW. Here, the guard count KCST is set according to this map. According to this map, the guard frequency KCST is set to a larger value as the cooling water temperature THW is lower. In the internal combustion engine 10, as the temperature is lower, it becomes difficult to secure the purge flow rate due to the effect of the ISC opening, and the amount of fuel required for starting increases due to the effect of friction. For this reason, it is appropriate that the guard frequency KCST for the crank angle asynchronous purge is set to a larger value as the cooling water temperature THW at the start is lower. According to the processing in step 232, the guard count KCST can be set so as to meet the request.

  In the routine shown in FIG. 9, next, an execution time TPGST for one crank angle asynchronous purge is set (step 234). As shown in the frame of step 234, the ECU 40 stores a map that defines the execution time TPGST in relation to the coolant temperature THW and the ISC opening. Here, the execution time TPGST is set according to this map. According to this map, the execution time TPGST per time is set to a larger value as the cooling water temperature THW is lower and the ISC opening is larger. In order to appropriately purge the evaporated fuel necessary for starting under conditions where the coolant temperature THW is low and the ISC opening is large, it is appropriate to secure a large execution time TPGST per one time. According to the processing of step 234, the execution time TPGST can be set so as to meet the request.

  In the routine shown in FIG. 9, next, a guard time KTST is calculated (step 236). As shown in the frame of step 236, the ECU 40 stores a map that defines the guard time KTST in relation to the cooling water temperature THW. Here, the guard time KTST is set according to this map. According to this map, the guard time KTST is set to a larger value as the cooling water temperature THW is lower. In the internal combustion engine 10, the total purge time required for purging the necessary amount of evaporated fuel becomes longer as the temperature is lower. According to the processing in step 236, the guard time KTST can be determined so as to meet the request.

  As described above, according to the routine shown in FIG. 9, the period determination value KSYUK, the crank angle asynchronous purge execution time TPGST, and the crank angle asynchronous purge guard according to the state when the internal combustion engine 10 is started. The number of times KCST and the guard time KTST can be set to appropriate values. For this reason, according to the system of the present embodiment, in addition to the effect of promoting the mixing of the evaporated fuel, the effect of improving the supply accuracy of the evaporated fuel can be obtained.

  In the second embodiment described above, the “asynchronous purge control means” according to the first aspect of the present invention is realized by the ECU 40 executing the process of step 222.

Embodiment 3 FIG.
[Features of Embodiment 3]
Next, Embodiment 3 of the present invention will be described with reference to FIG. 10 and FIG. The system of the present embodiment can be realized by causing the ECU 40 to execute the process shown in FIG. 11 described later instead of the series of processes shown in FIG. 8 in the system of the second embodiment.

  FIG. 10 is a timing chart for explaining the operation of the system of this embodiment. The timing chart shown in FIG. 10 is the same as the timing chart shown in FIG. 7 except that the white arrow corresponding to the initial crank angle asynchronous purge that is intermittently advanced is longer than the other arrows. It is.

  In the second embodiment described above, the crank angle asynchronous purge is continuously executed at the same cycle after the start of the internal combustion engine 10 is started. However, when the internal combustion engine 10 is started, the entire intake system is filled with air at atmospheric pressure. Then, when a flow is generated in the air, the intake air corresponding to the ISC opening starts to circulate. In order to create an air-fuel mixture suitable for starting under such circumstances, a certain amount of evaporated fuel is supplied to the intake system immediately after the start, and after that, when the intake air starts to flow, It is appropriate to reduce the fuel supply rate in accordance with the above.

  Therefore, as shown in FIG. 10C, the system of the present embodiment sets the initial crank angle asynchronous purge execution time TPGST to be sufficiently longer than the subsequent purge execution time TPGST. did. According to such a setting, the amount of evaporated fuel flowing into the intake system immediately after the internal combustion engine 10 is started can be increased as compared with the case of the second embodiment, and a situation in accordance with the above requirements can be created.

[Specific Processing in Embodiment 3]
FIG. 11 is a flowchart of a routine executed by the ECU 40 in the present embodiment in order to realize the above function. This routine is the same as the routine shown in FIG. 8 except that steps 240 to 248 are added after step 210. Hereinafter, of the steps shown in FIG. 11, the same steps as those shown in FIG. 8 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  In the routine shown in FIG. 11, after the cycle counter TSYUK is incremented in step 210, the start counter CST is incremented (step 240). Next, it is determined whether the count value of the start counter CST is equal to or greater than the initial cycle determination value KST (step 242).

  The start counter CST is set to 0 by the initial process. On the other hand, the initial cycle determination value KST is set to about half (for example, about 03 sec) of the entire execution period of the crank angle asynchronous purge. For this reason, it is determined that CST ≧ KST is not satisfied immediately after the start of the internal combustion engine 10 is started. In this case, it is next determined whether or not 1 is set in the initial purge execution flag XPGST (step 244).

  The initial purge execution flag XPGST is set to 0 by the initial process. For this reason, immediately after starting the internal combustion engine 10, it is determined that XPGST = 1 is not satisfied. In this case, first, the flag XPGST is set to 1 (step 246), and then the crank angle asynchronous purge execution time TPGST is replaced with the initial execution time KST1 (step 248). Thereafter, the processes of steps 222 and 224 are executed, whereby the first crank angle asynchronous purge is realized.

  The execution time TPGST is normally set to the same value as in the second embodiment. The initial execution time KST1 used in step 248 is slightly shorter than the initial cycle determination value KST and sufficiently longer than the normal set value (for example, 0.25 sec). For this reason, according to said process, the execution time of the first crank angle asynchronous purge can be fully extended compared with the case of Embodiment 2. FIG.

  Until the time corresponding to the initial cycle determination value KST elapses, the processing of step 244 is executed through step 242 each time this routine is started. In this case, since the establishment of XPGST = 1 is recognized in step 244, the present routine is ended without executing any processing.

  After the time corresponding to the initial cycle determination value KST has elapsed, in step 242, the establishment of CST ≧ KST is recognized. In this case, the processes in steps 212 to 224 are thereafter executed in the same manner as in the second embodiment. At this time, the D-VSV 26 uses a normal set value for the execution time TPGST. As a result, intermittent crank angle asynchronous purging with the same execution time TPGST as in the second embodiment is repeated.

  According to the above processing, immediately after the internal combustion engine 10 is started, the crank angle asynchronous purge can be continued for a relatively long period of time, and the evaporated fuel can be quickly supplied to the intake system. Further, at the stage where the intake air begins to circulate, it is possible to give priority to the promotion of fuel mixing by increasing the purge intermittent frequency. For this reason, according to the system of the present embodiment, excellent startability can be imparted to the internal combustion engine 10.

  In the third embodiment described above, the ECU 40 executes the process of step 224 so that the “control means” in the sixth or eighth invention executes the process of step 248. The “setting means” in the sixth or eighth invention is realized.

Embodiment 4 FIG.
[Features of Embodiment 4]
Next, a fourth embodiment of the present invention will be described with reference to FIG. 12 and FIG. The system of the present embodiment can be realized by causing the ECU 40 to execute the routine shown in FIG. 13 instead of the routine shown in FIG. 3 in the system of the first embodiment.

  FIG. 12 is a timing chart for explaining the operation of the system of this embodiment. The timing chart shown in FIG. 12 is the same as the timing chart shown in FIG. 2 except that the start timing of the crank angle asynchronous purge is delayed.

  In the first to third embodiments described above, the crank angle asynchronous purge is started immediately after the start of the internal combustion engine 10 is started. In the incomplete intake cylinder (# 1 cylinder in FIG. 2), the intake stroke is started simultaneously with the start of the internal combustion engine 10. Then, as described above, the evaporated fuel sucked in the intake stroke is discharged to the exhaust system without being subjected to combustion.

  The amount of evaporated fuel discharged in this way is preferably small from the viewpoint of improving the emission characteristics. That is, in order to obtain good emission characteristics, it is desirable that the amount of evaporated fuel sucked into the incomplete intake cylinder during the intake stroke immediately after the start is small. The amount of the evaporated fuel can be made so small that the time when the evaporated fuel starts to be purged by the crank angle synchronous purge after the start of the internal combustion engine 10 is delayed. Therefore, in the present embodiment, after the internal combustion engine 10 is started, execution of crank angle asynchronous purge is prohibited during a predetermined delay period set in advance.

[Specific Processing in Embodiment 4]
FIG. 13 is a flowchart of a routine executed by the ECU 40 in the present embodiment in order to realize the above function. This routine is the same as the routine shown in FIG. 3 except that step 250 is inserted after step 102. Hereinafter, of the steps shown in FIG. 13, the same steps as those shown in FIG. 3 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  In the routine shown in FIG. 13, when it is determined in step 102 that CCRNK ≦ −1 is satisfied, that is, when it is determined that no cylinder discrimination signal is generated, the count value of the start counter CST is set to the prohibited period KST02. Whether it is the above or not is determined (step 250). Then, if it is determined that the count value CST has not reached the prohibition period KST02, the current process is immediately terminated, and only when the CST is determined to have reached the prohibition period KST02, the crank angle asynchronous purge is performed. It is executed (steps 104 and 106).

  The prohibition period KST02 is set to a time that ends before the first intake stroke in the incomplete intake cylinder ends. That is, the time is set shorter than the time required for the intake stroke that is started simultaneously with the start of the internal combustion engine 10. More specifically, during the prohibition period KST02, the D-VSV 26 is opened at the end, and as a result, the time when the evaporated fuel actually starts to flow into the intake manifold 16 is the first intake stroke in the incomplete intake cylinder. It is set to coincide with the end time.

  According to the above setting, it is possible to sufficiently prevent the evaporated fuel by the crank angle asynchronous purge from being sucked into the incomplete intake cylinder in the first intake stroke. In addition, according to the above setting, the start of the crank angle asynchronous purge is delayed, thereby effectively preventing the amount of evaporated fuel supplied to the intake cylinder immediately before cylinder discrimination (# 3 cylinder in FIG. 12) from decreasing. be able to. For this reason, according to the system of the present embodiment, it is possible to improve the emission characteristics at the start without impairing the startability of the internal combustion engine 10.

  In the fourth embodiment described above, the “asynchronous purge prohibiting means” in the seventh or ninth invention is realized by the ECU 40 executing the processing of step 250.

It is a figure for demonstrating the structure of Embodiment 1 of this invention. 3 is a timing chart for explaining the operation of the first embodiment of the present invention. It is a flowchart of the main routine performed in Embodiment 1 of the present invention. It is a flowchart of the routine performed in order to implement | achieve crank angle synchronous purge in Embodiment 1 of this invention. It is a flowchart of the routine performed in order to implement | achieve correction | amendment purge in Embodiment 1 of this invention. It is a flowchart of the routine performed in order to open and close D-VSV in Embodiment 1 of this invention. It is a timing chart for demonstrating operation | movement of Embodiment 2 of this invention. In Embodiment 2 of this invention, it is a flowchart of a series of processes performed instead of step 104,106 shown in FIG. In Embodiment 2 of this invention, it is a flowchart of the routine performed in order to set a control parameter. It is a timing chart for demonstrating operation | movement of Embodiment 3 of this invention. It is a flowchart of the main routine performed in Embodiment 3 of the present invention. It is a timing chart for demonstrating operation | movement of Embodiment 4 of this invention. It is a flowchart of the main routine performed in Embodiment 4 of this invention.

Explanation of symbols

10 Internal combustion engine 16 Intake manifold 24 Purge passage 26 D-VSV
28 Canister 32 Air hole 40 ECU (Electronic Control Unit)
42 Ignition switch (IG switch)
44 Starter switch 46 Crank angle sensor 48 Water temperature sensor
MV intake pipe pressure
THW Cooling water temperature
NE engine speed
CCRNK Crank angle counter
TPGST Crank angle asynchronous purge execution time
CRNKPGS Crank angle synchronous purge start crank angle
CRNKPG purge advance amount # 1T to # 4T Corrected purge time
Initial execution time of KST1 crank angle asynchronous purge
KST02 Crank angle asynchronous purge prohibition time

Claims (9)

An evaporative fuel processing apparatus for supplying evaporative fuel to an internal combustion engine having a plurality of cylinders,
A canister that stores evaporative fuel;
A purge passage communicating the canister to the intake port of each cylinder;
A purge control valve provided for each cylinder to control the conduction state between the intake port of each cylinder and the canister;
A cylinder discrimination signal generating means for generating a cylinder discrimination signal at a specific crank angle during operation of the internal combustion engine;
Asynchronous purge control means for opening the purge control valves of all the cylinders and executing crank angle asynchronous purge after the start of the internal combustion engine and before the cylinder discrimination signal is generated,
At the time when the cylinder discrimination signal is generated, the time until the intake stroke starts after the non-inhaled asynchronous purge gas remains in the corresponding intake port and the cylinder discrimination signal is generated is determined. Correction purge control means for executing a correction purge by opening the purge control valve for cylinders exceeding a value;
An evaporative fuel processing apparatus comprising:   2. The correction purge target cylinder includes an intake cylinder immediately after cylinder discrimination in which an intake stroke is started following a cylinder discrimination cylinder in which an intake stroke is started simultaneously with generation of a cylinder discrimination signal. Evaporative fuel processing device.   The correction purge target cylinder includes an incomplete intake cylinder that overlaps with the execution period of the crank angle asynchronous purge and that has executed the intake stroke so as to end before the crank angle asynchronous purge ends. The evaporative fuel processing apparatus according to claim 1 or 2, characterized in that:   4. The evaporated fuel processing apparatus according to claim 3, wherein the correction purge control means applies a larger amount of correction purge to the incomplete intake cylinder than to other target cylinders. Initial purge cylinder setting in which the cylinder in which the intake stroke is first performed among the cylinders in which the non-inhaled asynchronous purge gas does not remain in the corresponding intake port when the cylinder discrimination signal is generated is the crank synchronous initial purge cylinder Means,
Synchronous purge control means for performing a crank angle synchronous purge by opening the purge control valves of the individual cylinders in synchronization with the crank angle from the crank synchronous initial purge cylinder after generation of the cylinder discrimination signal;
The evaporative fuel processing apparatus of any one of Claims 1 thru | or 4 characterized by the above-mentioned. The asynchronous purge control means includes
Control means for controlling the purge control valve so that the purge control valve is opened and closed a plurality of times before the cylinder discrimination signal is generated after the start of the internal combustion engine;
A setting means for setting the valve opening time in the plurality of initial times longer than the valve opening time in the second and subsequent times;
The evaporative fuel processing apparatus of any one of Claims 1 thru | or 5 characterized by the above-mentioned.   The evaporated fuel processing according to any one of claims 1 to 6, further comprising asynchronous purge prohibiting means for prohibiting start of the crank angle asynchronous purge for a predetermined time after the start of the internal combustion engine. apparatus. An evaporative fuel processing apparatus for supplying evaporative fuel to an internal combustion engine having a plurality of cylinders,
A canister that stores evaporative fuel;
A purge passage communicating the canister to the intake port of each cylinder;
A purge control valve provided for each cylinder to control the conduction state between the intake port of each cylinder and the canister;
A cylinder discrimination signal generating means for generating a cylinder discrimination signal at a specific crank angle during operation of the internal combustion engine;
An asynchronous purge control means for opening the purge control valves of all the cylinders and executing a crank angle asynchronous purge after the start of the internal combustion engine is started and before the cylinder discrimination signal is generated,
The asynchronous purge control means includes
Control means for controlling the purge control valve so that the purge control valve is opened and closed a plurality of times before the cylinder discrimination signal is generated after the start of the internal combustion engine;
A setting means for setting the valve opening time in the plurality of initial times longer than the valve opening time in the second and subsequent times;
The evaporative fuel processing apparatus characterized by including. An evaporative fuel processing apparatus for supplying evaporative fuel to an internal combustion engine having a plurality of cylinders,
A canister that stores evaporative fuel;
A purge passage communicating the canister to the intake port of each cylinder;
A purge control valve provided for each cylinder to control the conduction state between the intake port of each cylinder and the canister;
A cylinder discrimination signal generating means for generating a cylinder discrimination signal at a specific crank angle during operation of the internal combustion engine;
Asynchronous purge control means for opening the purge control valves of all the cylinders and executing crank angle asynchronous purge after the start of the internal combustion engine and before the cylinder discrimination signal is generated,
Asynchronous purge prohibiting means for prohibiting the start of the crank angle asynchronous purge for a predetermined time after the start of the internal combustion engine,
An evaporative fuel processing apparatus comprising:

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