JPS6394063A - Evaporated fuel treating device for engine - Google Patents

Abstract

PURPOSE:To prevent promotion of the variation of air-fuel ratio during acceleration of engine, by limiting purge of evaporated fuel during acceleration. CONSTITUTION:A controller 24 operates a basic fuel injection quantity based on an intake air quantity detected through an air flow meter 21 and a rotation detected through a rotation sensor SER, and decides that an engine is under acceleration if the variation rate of the opening of a throttle valve detected through a throttle valve opening sensor 22 is higher than a setting value thus setting an acceleration increment rate. A controller 29 decides whether the evaporated fuel must be purged based on said acceleration increment rate, and if the evaporated fuel must be purged, a purge changeover valve 19 is switched to lead an intake negative pressure into a negative pressure chamber 15c of a purge valve 15. If the acceleration increment rate is higher than a setting value, the negative pressure chamber 15c is opened to the atmosphere thus cutting the purge.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in an engine vaporized fuel processing device that supplies vaporized fuel spontaneously emitted from a fuel tank or the like to the engine.

(Prior Art) Conventionally, as disclosed in Japanese Utility Model Application Publication No. 58-51049, a canister containing activated carbon for collecting evaporated fuel, and a canister containing activated carbon for collecting evaporated fuel have been conventionally used as an evaporative fuel processing device for an engine. A purge passage for supplying evaporated fuel from the engine to the intake system of the engine is provided, and during engine operation, the evaporated fuel is purged to the intake system together with air to prevent the evaporated fuel from being released into the atmosphere. There is something to do.

(Problems to be Solved by the Invention) By the way, there is a problem that the air-fuel ratio fluctuates sharply when the engine is running at an accelerated speed, but in the above-mentioned publication, vaporized fuel is purged even when the engine is running at an accelerated speed. This has the disadvantage that air-fuel ratio fluctuations are exacerbated by the purge of evaporated fuel, resulting in deterioration of emission performance.

The present invention has been made in view of the above, and its purpose is to prevent air-fuel ratio fluctuations during acceleration by restricting the purge of evaporated fuel to the intake system during engine acceleration. The goal is to prevent

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention is as shown in FIG.
The present invention is directed to an evaporative fuel processing device for an engine, which is equipped with a evaporative fuel supply means 16 for supplying evaporative fuel from the evaporative fuel collecting means 10 to an intake system. Then, an acceleration operation detection means 31 detects the acceleration operation of the engine, and the output of the acceleration operation detection means 31 is received to limit the amount of vaporized fuel supplied by the vaporized fuel supply means 16 during the acceleration operation of the engine. The configuration is such that a restriction means 32 is provided.

(Function) With the above configuration, in the present invention, the evaporated fuel collecting means 1
The evaporated fuel collected at 0 is supplied to the intake system of the engine by the evaporated fuel supply means 16, and during acceleration operation of the engine, it is detected by the acceleration operation detection means 31. The supply m of the vaporized fuel is limited by the limiting means 32 which receives the output of the fuel vapor. Therefore, the promotion of fluctuations in the air-fuel ratio during accelerated driving is prevented as much as possible.

(Example) Hereinafter, an example of the present invention will be described based on the drawings from FIG. 2 onwards.

FIG. 2 shows the overall configuration of the evaporative fuel processing system for an engine according to the present invention, in which 1 is the engine, 2 has one end communicating with the atmosphere, and the other end opening into the engine 1 to supply intake air to the engine 1. The intake passage 2 has an air cleaner 3 at its upstream end that cleans intake air;
A throttle valve 4 controls the amount of intake air on the downstream side of the air cleaner 3, and a throttle valve 4 controls fluctuations in the amount of intake air on the downstream side of the throttle valve 4. ! A surge tank 5 that injects fuel into the engine 1, and a fuel injection valve 6 that injects and supplies fuel toward the engine 1 are provided downstream of the surge tank 5.

Further, a canister 10 is arranged above the fuel tank 7 as a means for collecting evaporated fuel that adsorbs evaporated fuel that has evaporated through the evaporation tube 8 . The canister 10 has an adsorbent 10b housed in a cylindrical casing 10a, and a lower space inside the casing 10a is connected to a communication pipe 13.
The evaporation pipe 8 and the purge passage 11 for distributing the evaporated fuel to the intake passage 2 are in communication with the f'A cross section (atmosphere) of the side frame 14 through the casing 10a, and in the upper space inside the casing 10a are the evaporation pipe 8 and a purge passage 11 for circulating the evaporated fuel to the intake passage 2. There is a continuous connection. The other end of the purge passage 11 is connected to a purge supply port 12 that opens near the downstream side of the throttle valve 4 of the intake passage 2. A purge valve 15 is provided. The purge valve 15 includes a communication chamber 15a which is opened in the middle of the purge passage 11;
A diaphragm 15b that opens and closes the opening end 11a of the purge passage 11 to the communication ¥15a, a negative pressure chamber 15C separated from the communication chamber 15a by the diaphragm 15b, and a negative pressure chamber 15C that is compressed into the negative pressure chamber 15c and closes the diaphragm 15b. It is provided with a spring 15d that biases in the direction. The negative pressure chamber 15c is connected via a negative pressure introduction passage 18 to a negative pressure outlet 17 (V
C hole), and when the throttle valve 4 is opened to a predetermined opening degree or more, that is, during normal operation excluding idling operation, the intake negative pressure generated at the negative pressure outlet 17 is transferred to the negative pressure chamber 1.
I am trying to introduce it in 5c. A purge switching valve 19 consisting of a three-way valve is interposed in the negative pressure introduction passage 18, and when the purge switching valve 19 is switched, the purge valve 1
The pressure in the negative pressure chamber 15c of No. 5 is switched between atmospheric pressure and the intake negative pressure of the intake passage 2, and the purge of evaporated fuel is adjusted. However, when the intake angle EE is introduced into the negative pressure chamber 15c, the diaphragm 15b moves against the force of the spring 15d due to this intake negative pressure, and the evaporated fuel flows through the purge passage 11. is purged into the intake passage 2. On the other hand, when the negative pressure chamber 15c is opened to the atmosphere, the spring 1
The diaphragm 15b is closed by the biasing force 5d, the purge passage 11 is closed rJ1, and the evaporated fuel is not purged into the intake passage 2.

The purge passage 11 and the purge valve 15 constitute a fuel vapor supply means 16 that supplies the fuel vapor in the canister 10 (fuel vapor collecting means) to the intake system.

In addition, in the purge passage 11, 20 is the canister 1.
This is a check valve that prevents the evaporated fuel collected at 0 from flowing back into the fuel tank 7.

Furthermore, in FIG. 2, 21 is 1ffl on the upstream side of the throttle valve 4 in the intake passage 2 and below the air cleaner 3! 1 is an air flow sensor that detects the amount of intake air; 22 is a throttle valve opening sensor that detects the opening of the throttle valve 4;
Reference numeral 3 denotes a negative pressure switch that is turned on when the pressure in the negative pressure center entry passage 18 (the pressure downstream of the throttle valve 4 in the intake passage 2) becomes a predetermined value or less;
Each of the detection signals 1 to 23 is sent to the CPU and R
The controller 24 controls the fuel injection valve 6 and the purge switching valve 19, respectively, and controls the amount of fuel injected into the engine 1 and the intake air. and 1I purge of evaporated fuel, respectively.
iI is adjusted.

FIG. 3t shows the internal configuration of the controller 24. In FIG. 3, 25 is a pulse calculation circuit that receives signals from the engine rotation speed sensor SEP and the air flow sensor 21 and calculates the basic fuel injection pulse width τO, and 26 is a pulse calculation circuit. An acceleration determination circuit 27 receives the opening signal from the throttle valve opening sensor 22, calculates the opening change rate, and determines acceleration based on the value of the opening change rate. For acceleration, an acceleration increase m-port circuit calculates an acceleration increase rate CAC of the fuel I@Nishiki pulse according to the acceleration, and 28 receives signals from the pulse calculation circuit 25, acceleration increase calculation circuit 27, etc., and calculates the final fuel injection pulse τ. It is a general calculation circuit that sieves based on τ-τ0X(1+CAC), and the signal of the general calculation circuit 28 is output to the fuel injection valve 6, and the fuel according to the fuel injection pulse τ is injected from the fuel injection valve 6. It is designed to be sprayed. The second part receives the output of the acceleration increase m calculation circuit 27 and determines whether to purge the evaporated fuel according to the magnitude of the acceleration increase rate CAC, and when purging the evaporated fuel, switches the purge. This is a purge control circuit that controls the valve 19 so as to introduce the intake negative pressure into the negative pressure chamber 15c of the purge valve 15, and to open the negative pressure chamber 15c to the atmosphere when purging is not performed.

Next, the fuel supply m control and vaporized fuel purge control by the controller 24 will be explained based on the flowchart of FIG. 4.

In FIG. 4, in step S1, the signal values of the engine speed, intake air ■, and opening degree TVO of the throttle valve 4 are read, and in step S2, the conditions of the engine speed and intake air amount read in step S+ are applied. The basic fuel pulse width τO of the fuel is calculated accordingly, and in step S3,
Above throttle valve fff1 degree TVcl) change *d TV
O/dl setting (determine whether it is larger than iaA. YE if the determination in step S3 is dTVO/dt>A)
When S, it is determined that the acceleration operation is in progress, and the acceleration increase rate CAC of the fuel injection pulse is set to the set value A in step S4, and the process proceeds to step S7, while the determination in step S3 is d.
If TVo/dt≦A (NO), which is not the acceleration operation, the process moves to step S51, and in step S5 it is determined whether the acceleration increase rate CAC is zero, and if the acceleration increase rate CAC is not zero (No), the operation is accelerated. Determining that it is time to transition to a later steady state operation, the acceleration increase rate CAC is gradually decreased by a predetermined mΔA in step S6, and when CAC=0 (YES), the process proceeds to step S7). In step S7, acceleration 1
Determine whether or not the so-correspondence ratio CAC is O, and determine whether CAC=O.
In the case of ES, it is determined that the operation is not in acceleration operation but in steady operation, and in step S8, the two purge control circuits control one of the purge switching valves to close the purge valve 15 to purge the evaporated fuel. I do. On the other hand, during acceleration operation where the determination of +1'3 in step SA is No, CAC≠0, and immediately after that, the process proceeds to step S9, and the two purge control circuits close the purge valve 15. Switch the purge switching valve 19 to evaporated fuel r1
Cut the purge. Then, in step S+o, the fuel injection valve 6 is driven with the fuel injection pulse width (DA at τO·(1+CAc)+) calculated by the general calculation circuit 28, and the fuel injection valve 6 is driven according to the fuel injection pulse width. Perform fuel injection. Note that here, τBA is a fuel injection pulse variation correction valve.

In the above flow, step S3 configures an acceleration operation detecting means 31 for detecting the acceleration operation of the engine, and step S9 receives the output of the acceleration operation detection means 31, and receives the output of the acceleration operation detecting means 31, and receives the output of the acceleration operation detecting means 31 in step S9. 1
A limiting means 32 for limiting the supply of evaporated fuel by 6 is configured.

Therefore, in the above embodiment, as shown in FIG. 5, the purging of the evaporative fuel is cut off during acceleration operation of the engine, so that the air-fuel ratio fluctuates due to the purge of the evaporative twister 31 during acceleration operation where air-fuel ratio fluctuations are large. The promotion of this is effectively prevented.

Furthermore, at the time of transition to steady operation after acceleration (predetermined time t1 or jz after the end of acceleration operation in FIG. 5), a purge cut of evaporated fuel is performed while gradually decreasing the acceleration reserve rate CAC. Therefore, the increase in air-fuel ratio fluctuation is reliably prevented even when the acceleration amount is increased immediately after the end of acceleration operation.

In the above embodiment, the restricting means 32 cuts off the purge of vaporized fuel, but it may also reduce the purge amount, and its structure may include various on-off valves, flow R adjustment valves, etc. can be used.

(Effects of the Invention) As explained above, in an engine vapor fuel processing device that purges vapor fuel into the intake air of the engine, the purging of vapor fuel is limited during acceleration operation, so that the air-fuel ratio during acceleration operation is reduced. It is possible to effectively prevent fluctuations in the fuel temperature from being further exacerbated by purging of evaporated fuel.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 to 5 show an embodiment of the present invention, FIG. 2 is a block diagram of the body, FIG. 3 is a block diagram showing the internal configuration of the controller, and FIG. 4 is a flowchart showing the control procedure by the controller. Figure 1 and Figure 5 are full explanatory diagrams. 10... Canister (evaporated fuel supply means), 16...
- Evaporated fuel supply means, 31... acceleration operation detection means,
32...Restriction means. Figure 1 Figure 4

Claims (1)

[Claims] (1) Acceleration operation that includes a fuel vapor collection means that collects fuel vapor and a fuel vapor supply means that supplies the fuel vapor from the fuel vapor collection means to the intake system, and detects when the engine is being accelerated. An evaporative fuel for an engine, characterized in that it is equipped with: a time detecting means; and a limiting means that receives the output of the accelerating operation detecting means and limits the amount of evaporative fuel supplied by the evaporative fuel supply means during accelerating operation of the engine. Processing equipment.