JPH0645652Y2 - Evaporative fuel control device for engine - Google Patents

Description

[Detailed Description of the Invention] (Industrial field of application) The present invention supplies the evaporated fuel evaporated in the fuel tank (specifically, fuel evaporative gas) to the engine for combustion processing (purging). The present invention relates to an evaporated fuel control device for controlling.

(Prior Art) Conventionally, such a fuel vapor is supplied to an engine and processed by combustion, for example, Jikken Sho 61.
As disclosed in Japanese Laid-Open Patent Publication No. -23644, etc., the engine speed and load are detected, and the supply amount of evaporated fuel is low in the low speed and low load region of the engine, and conversely increases in the high speed and high load region, It is known that the evaporated fuel is supplied in proportion to the operating state of the engine.

By the way, when the evaporated fuel is supplied during the idling operation of the engine, the supplied air-fuel ratio changes the air-fuel ratio of the intake air, which deteriorates the combustibility and impairs the idle stability. It is common practice to supply evaporated fuel only when it is in the operating region. Then, in that case, when the engine shifts from the idle region where the intake air amount is small to the non-idle region, the degree of change in the intake air amount increase is large, so the evaporated fuel is not supplied until the change is stopped, and the throttle valve The supply of the evaporated fuel is started only when a predetermined time has passed after the closed state is opened.

(Problems to be solved by the invention) By the way, in recent years, the vaporized fuel in the fuel tank tends to increase with the expansion of the vehicle compartment space in the vehicle and the increase in the output of the engine. Therefore, it becomes difficult to adsorb, and overflow may occur. For this reason, it is desired to supply the evaporated fuel to the engine as much as possible within a range that does not adversely affect the drivability of the engine.

However, as described above, when the supply of the evaporated fuel is started after a certain time has passed after the throttle valve was opened, the range in which the evaporated fuel can be supplied is narrowed, and it is difficult to achieve the above requirements satisfactorily. .

The present invention has been made in view of the above circumstances, and an object thereof is to set the time until the fuel supply is started when the supply of the evaporated fuel is started after a lapse of a predetermined time after the throttle valve is opened. By changing the intake air amount according to the degree of change in the intake air amount, the evaporated fuel supply can be started, and the evaporated fuel supply region is expanded while suppressing the air-fuel ratio deviation due to the evaporated fuel supply. To improve the processing capability of evaporated fuel.

(Means for Solving the Problem) In order to achieve the above object, the solution means of the present invention detects the engine speed when the throttle valve is opened from the closed state, and when the speed is high, it is lower than when it is low. Also set a short time until the start of fuel vapor supply.

That is, the present invention, as shown in FIG.
It is premised on an evaporated fuel control device for an engine that controls the evaporated fuel that is supplied to and processed in accordance with the operating state of the engine 1.

Evaporative fuel supply means 37 is provided for starting the supply of evaporated fuel when a predetermined time has elapsed after the throttle valve 14 of the engine 1 was opened from the closed state.

Also, engine rotation detecting means for detecting the engine speed
38 is provided.

Further, when the output of the engine rotation detecting means 38 is received, the time taken to start the supply of the evaporated fuel after the throttle valve 14 is opened by the evaporated fuel supply means 37 is shorter when the engine speed is high than when it is low. A supply start timing correction means 39 for correction is provided.

(Operation) According to the present invention, according to the present invention, when the throttle valve 14 of the engine 1 is opened from the closed state, the evaporative fuel supply means 37 elapses a predetermined time after the opening operation of the throttle valve 14 to evaporate fuel. Are supplied to the engine 1 and processed by combustion.

In that case, the engine speed is detected by the engine speed detection means 38, and the supply start timing correction means 39 receiving the output of the detection means 38 evaporates after the throttle valve 14 is opened from the closed state when the engine speed is high. The predetermined time until the fuel supply is started becomes shorter than the same time when the engine speed is low. That is, when the throttle valve 14 is opened in a low speed region such as the idle operation region of the engine 1, the intake air amount is greatly increased and changed, and it takes a long time for the intake air-fuel ratio to stabilize.
After a long time has passed since the valve was opened, the evaporated fuel is supplied.

On the other hand, when the throttle valve 14 is opened from the closed state in the high speed range of the engine 1, for example, when the throttle valve 14 is fully closed by deceleration of the engine 1 and then re-accelerated, the high speed range is originally drawn. The amount of air is large, and the degree of change in the amount of intake air is small even if the throttle valve 14 is opened after being closed. At this time, even if the time from the opening operation of the throttle valve 14 to the start of the supply of the evaporated fuel is short, the air-fuel ratio does not become unstable, and the evaporated fuel is supplied after a short time has elapsed from the opening operation of the throttle valve 14. To be done. Therefore, the region where the evaporated fuel is supplied can be expanded without suppressing the deviation of the air-fuel ratio and deteriorating the combustibility of the engine 1.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings starting from FIG.

FIG. 2 shows the overall configuration of an embodiment of the present invention, in which 1 is an engine, which is a cylinder block 3 having a cylinder 2, a cylinder head 4 joined to the upper surface of the cylinder block 3, and an inside of the cylinder 2. And a reciprocating piston 5, and a combustion chamber 6 defined by the lower surface of the cylinder head 4 and the top surface of the piston 5 is formed in the cylinder 2. Reference numeral 7 is an intake passage for supplying intake air into the combustion chamber 6, and 9 is an intake valve for opening and closing a downstream end opening of the intake passage 7. Reference numeral 10 is an exhaust passage for discharging exhaust gas in the combustion chamber 6, 11 is an exhaust valve for opening and closing an upstream end opening of the exhaust passage 10, and 12 is an exhaust purification device disposed in the middle of the exhaust passage 10.

In the intake passage 7, an air flow meter 13 that detects the intake air amount Q, a throttle valve 14 that throttles the intake passage 7, a surge tank that absorbs intake pulsation, etc., in this order from the upstream side.
15 and an injector 16 for injecting and supplying fuel are arranged,
The upstream end of the intake passage 7 is connected to the air cleaner 17. Reference numeral 8 is a bypass passage that bypasses the throttle valve 14 and supplies the intake air amount to the combustion chamber 6. In the middle of the bypass passage 8, when the engine 1 is idling, the intake air amount in the bypass passage 8 is controlled to control the engine speed (idle rotation speed). An idle speed control valve 18 consisting of a proportional solenoid valve for adjusting the number) is provided.

A fuel tank 19 is connected to the injector 16 via a fuel supply device (not shown). The fuel tank 19 has an upper portion for supplying the evaporated fuel (fuel evaporative gas) in the tank 19 to the engine 1. The upstream end of the evaporated fuel passage 20 is open, and the downstream end of the evaporated fuel passage 20 is the surge tank.
It opens to the intake passage 7 at 15. Evaporative fuel passage 20
In the middle of, the separator 21 for separating the liquid fuel from the evaporated fuel, the two-way valve 22, the canister 23 for adsorbing the evaporated fuel, and the evaporated fuel passage 20 are opened and closed in order from the upstream side (fuel tank 19 side). A solenoid valve 24 for adjusting the supply (barge) of the evaporated fuel to the intake passage 7 is provided, and the separator 21 is connected to the fuel tank 19 through a fuel return passage 25 for returning the separated liquid fuel. There is.

The injector 16, the idle speed control valve 18 and the solenoid valve 24 are configured to be operated and controlled by a control unit 30 having a built-in CPU. The comment roll unit 30 includes a detection signal of the air flow meter 13, a detection signal of an intake air temperature sensor 31 for detecting the intake air temperature in the intake passage 7 immediately downstream of the air cleaner 17, and a throttle sensor for detecting the opening of the throttle valve 14. 32, a detection signal of a crank angle sensor 33 that detects the crank angle of the engine 1 based on the rotation angle of the camshaft 4a in the cylinder head 4, a rotation signal of the distributor 34, and the upstream side of the exhaust purification device 12 described above. The detection signal of the O ₂ sensor 35 disposed in the exhaust passage 10 and the detection signal of the water temperature sensor 36 that detects the temperature of the cooling water inside the water jacket 3a in the cylinder block 3 are input. Although not shown, the throttle sensor 32 is provided with an idle switch for outputting an ON signal when the throttle valve 14 is fully closed and the throttle opening becomes zero.

Solenoid valve in the control unit 30
A signal processing procedure for controlling the supply of the evaporated fuel to the intake passage 7 by the operation control of 24 will be described with reference to FIGS. 3 to 7. FIG. 5 shows that the idle speed control (abbreviated here as ISC) is stopped to control the opening of the idle speed control valve 18 in a feedback manner to keep the idle speed of the engine 1 at a constant target speed. A sub-routine for performing the time determination after the operation is shown. This routine determines first, the ISC in step S ₂₁ after the start running, i.e. whether the engine 1 is in an idle region. Distributor 34
When the engine speed Ne calculated based on the rotation signal of is less than the set idle speed (for example, 1000 rpm) and the idle switch outputs the ON signal (when the throttle valve 14 is fully closed), the idle speed The opening of the control valve 18 is set in the ISC region for feedback control. Now it is determined as YES in the ISC execution, terminates by setting the first timer to the first set time (e.g. 23 seconds) in step S _22. Further, when the determination is NO in the non-execution of the ISC, the count value of the first timer in step S ₂₃ "1" only reduce and exit decremented.

Further, FIG. 6 shows a subroutine for judging the elapsed time after the throttle valve 14 is opened from the fully closed state and the idle switch is switched from the ON state to the OFF state. _{At 31} it is determined whether the idle switch is ON. When this determination is YES for the idle switch ON, the second timer is set to a second set time (for example, 13 seconds) shorter than the first set time in step S ₃₂ , and the process is ended. The determination is negative (NO) of the idle switch OFF ends at step S ₃₃ after performing the decrement process of the timer by subtracting "1" from the count value of the second timer.

Further, FIG. 7 shows a subroutine for determining the load state of the engine 1. In this routine, first, it is determined whether the engine load is above a predetermined value in step S _41. As the engine load, for example, a basic fuel injection amount Tp = K · (Q / Ne) obtained by dividing the intake air amount Q detected by the air flow meter 13 by the engine speed Ne and multiplying it by a coefficient K is used. . If this determination is YES, that is, engine load ≧ predetermined value, the engine 1 is in the high load range where the output is required, so in step S ₄₂ , the barge determination flag xtper is set to “1” indicating that the supply (purging) of evaporated fuel is prohibited. "It ends after setting to. Further, when the determination is NO of engine load <predetermined value, the purge determination flag xtper is set to "0" for purge execution, and then the process ends.

FIG. 3 is a subroutine for determining the supply of evaporated fuel, that is, the execution of purging. First, in step S ₁ after the start, the count value of the first timer is “0”, that is, the idle region of the engine 1. After the throttle valve 14 is opened, it is determined whether the first set time (23 seconds) has elapsed. If the decision is YES count value = 0, the process proceeds to step S _2, this time the count value of the second timer is "0", i.e., the second set time from the throttle valve 14 is opened (13 Second) has elapsed. When this determination is YES with the count value = 0,
Step S ₃ above purge judgment flag Xtper is determined whether the xtper = 0, this determination indicates opening operation instruction of the solenoid valve 24 a solenoid operated flag xpg Step S ₄ when the YES of xtper = 0 "1 "It ends after setting to. Moreover, the judgment is made in any of the above steps S ₁ , S ₂ , and S _3.
When NO, and the routine proceeds to step S _5, and ends after setting the solenoid actuated flag xpg to "0" indicating the closing operation command of the solenoid valve 24.

Further, FIG. 4 shows a subroutine for controlling the operation of the solenoid valve 24. In this routine, first,
In step S ₁₁ , the solenoid operation flag xpg is xpg = 1.
Whether it is determined, step when the judgment is then opened it outputs the opening operation command signal to the solenoid valve 24 at step S ₁₂ is affirmative (YES) of xpg = 1, also the determination of xpg = 0 NO after closing it outputs a closing command signal to the solenoid valve 24 in S _13, i.e. ends, respectively, when the engine 1 is in the ISC region, executes the flow of steps S _1, S ₅ in the purge execution determination subroutine However, the solenoid valve 24 is closed and the evaporated fuel is not supplied. Then, when the engine 1 shifts from the ISC region to another operating region, the first and second timers start counting, and after the counts of both timers start, the first timer starts counting.
When the first timer counts up (becomes to zero) after the set time (23 seconds) has passed, the same step is executed.
The flow of S ₁ and S ₂ is executed, and the solenoid valve 24 is opened in the medium load range of the engine 1 to supply the evaporated fuel.

On the other hand, when the throttle valve 14 is closed to the fully closed state due to the deceleration of the engine 1, the flow of steps S ₁ , S ₂ and S ₅ is executed in the above-described purge execution determination subroutine, and the evaporated fuel is not supplied. Thereafter, when the engine 1 shifts to the acceleration state and the throttle valve 14 is opened from the closed state, the second timer starts counting, and the second timer counts up, so that the solenoid valve is operated in the medium load range of the engine 1. 24 is opened to supply evaporated fuel.

Therefore, in this embodiment, by all the steps in the above flow, when the engine 1 is in the medium load range lower than the predetermined value, the throttle valve 14 is opened from the closed state and the idle switch is switched from the ON state to the OFF state. After that, the evaporated fuel supply means 37 is configured to start the supply of the evaporated fuel when a predetermined time set by the first or second timer has elapsed.

Further, by the steps S ₁ and S ₂ , the engine rotation detection means 38 is configured to indirectly detect the engine rotation speed as the rotation speed of the ISC region or the rotation region of the other operating region. Has been done.

Further, in the steps S ₁ , S ₂ , S _{21 to} S ₂₃ , S _{31 to} S ₃₃ , the output of the engine rotation detecting means 38 is received, and in the region where the engine speed is high, that is, in the non-idle operation region of the engine 1, A second set time (13 seconds) is a time period from when the throttle valve 14 is opened by the evaporative fuel supply means 37 to when the throttle valve 14 is opened to when the evaporative fuel supply is started. Therefore, the supply start time correction means 39 is configured to correct the same time when the throttle valve 14 is opened, that is, shorter than the first set time (23 seconds).

Therefore, in the above embodiment, the control unit 30 detects the operating state of the engine 1 and
Is in the idle region, the throttle valve 14 is fully closed and the engine speed Ne is equal to or lower than the set idle speed, the ISC region is set. In this region, the first timer is set to an initial value other than zero, and the second timer is also set to an initial value other than zero by the ON operation of the idle switch. As a result, the solenoid valve 24 is closed and the evaporated fuel passage 20 is closed, and the intake passage 7 of the engine 1 is closed.
Fuel vapor is not supplied to the.

On the other hand, when the engine 1 shifts from the idle region to another operating region, the first timer starts counting and the second timer also starts counting because the idle switch operates from the ON state to the OFF state. After the start of counting by both timers, the first set time (23
Seconds) elapses and the first timer counts up,
The solenoid valve 24 opens in the medium load range of the engine 1. Therefore, the evaporated fuel is started to be supplied after the first set time has elapsed since the throttle valve 14 was opened. That is, when the throttle valve 14 is opened from the idle operation region of the engine 1, the intake air amount is greatly increased and changed, and it takes a long time for the intake air-fuel ratio to stabilize. At this time, a long first set time (23 seconds) Since the evaporative fuel is supplied after the time elapses, it is possible to suppress deterioration of the combustibility of the engine 1.

Further, when the engine 1 is in an operating region other than the non-idle region and the throttle valve 14 is closed in the fully closed state and the engine 1 is in the deceleration state, the closing operation of the throttle valve 14 causes the idle switch to be turned on. Therefore, the first timer is set to the desired value, the solenoid valve 24 is closed, and the supply of evaporated fuel to the engine 1 is interrupted. After that, when the engine 1 shifts to the acceleration state and the throttle valve 14 opens from the fully closed state,
When the idle switch is turned off from the ON state, this ON operation causes the second timer to start counting, and when the second timer counts up after the second set time (13 seconds) has elapsed, the solenoid valve 24 turns on. Open again. Therefore, the evaporated fuel is supplied after the second set time has elapsed since the throttle valve 14 was opened. That is, when the throttle valve 14 is opened from the closed state in the high speed range of the engine 1, the intake air amount is originally large in the high speed range, and even if the throttle valve 14 is opened after being closed, the degree of change in the intake air amount is high. Is small. At this time, even if the time from the opening operation of the throttle valve 14 to the start of the supply of the evaporated fuel is short, the air-fuel ratio does not become unstable.
The evaporative fuel is supplied after the elapse of the set time. Therefore, it is possible to expand the region for supplying the evaporated fuel and improve the processing capability of the evaporated fuel without suppressing the deviation of the air-fuel ratio of the intake air due to the supply of the evaporated fuel and deteriorating the combustibility of the engine 1. it can.

(Effect of the Invention) As described above, according to the evaporated fuel control device for an engine of the present invention, when a predetermined time elapses after the throttle valve is opened from the closed state, the evaporated fuel is supplied to the engine and the engine speed is detected. However, when the rotation speed is high, the time from the opening operation of the throttle valve to the start of the supply of evaporated fuel is shorter than when it is low, so the supply of evaporated fuel is started according to the degree of change in the intake air amount. You can
It is possible to expand the evaporative fuel supply region and improve the evaporative fuel processing capacity while suppressing the deviation of the air-fuel ratio due to the evaporative fuel supply.

[Brief description of drawings]

FIG. 1 is a diagram showing the configuration of the present invention. FIG. 2 and the following drawings show an embodiment of the present invention, FIG. 2 is an explanatory view showing the overall configuration thereof, FIG. 3 is a flow chart showing the signal processing procedure of the purge execution determination subroutine in the control unit, and FIG. Is a flow chart showing the signal processing procedure of the solenoid valve operating subroutine, and FIG.
The flowchart which shows the signal processing procedure of the time judgment subroutine after ISC execution stop, FIG. 6 is the same idle switch
FIG. 7 is a flowchart showing the signal processing procedure of the time determination subroutine after the OFF operation, and FIG. 7 is a flowchart showing the signal processing procedure of the engine load determination subroutine. 1 ... Engine, 7 ... Intake passage, 14 ... Throttle valve, 18 ... Idle speed control valve, 20 ...
… Evaporated fuel passage, 24 …… Solenoid valve, 30 …… Control unit, 32 …… Throttle sensor, 37 …… Evaporated fuel supply means, 38 …… Engine rotation detection means, 39 ……
Supply start time correction means.

Claims (1)

[Scope of utility model registration request] 1. An evaporative fuel control system for an engine, wherein evaporative fuel supplied to and processed by an engine is controlled in accordance with an operating state of the engine, and a predetermined time elapses after a throttle valve of the engine is opened from a closed state. When the engine speed is high, the evaporated fuel supply means for starting the supply of the evaporated fuel, the engine speed detecting means for detecting the engine speed, and the output of the speed detecting means are used as compared with when the engine speed is low. An evaporative fuel control device for an engine, comprising: a supply start timing correction unit that corrects a time period until the supply of the evaporated fuel is started after the throttle valve is opened by the fuel supply unit.