JPH06280689A - Evaporated fuel processor for engine - Google Patents

Abstract

PURPOSE:To enable purge while preventing evaporated fuel from excessive purge amount even in idling of an engine. CONSTITUTION:A machanical throttle valve 14 interlocked with an accelerator pedal 13 and an electrical throttle valve 12 located upsteam of the throttle valve 14 are disposed in an intake path 8. In an engine 1 having the opening of the electrical throttle valve 12 set larger than the machanical throttle valve 14 in an idling region, the downstream end of a evaporated fuel supply path 23 for supplying evaporated fuel in a fuel supply system to an intake system is opened to the intake path 8 between the machanical throttle valve 14 and electrical throttle valve 12 to purge the evaporated fuel to the intake path 8 between both throttle valves 12, 14 having intake negative pressure smaller than that in the downstream of the machanical throttle valve 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evaporated fuel processing apparatus for supplying evaporated fuel from a fuel supply system such as a fuel tank to an intake system of an engine for processing.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Unexamined Patent Publication No. 4-17983.
No. 8, etc., a mechanical throttle valve that opens and closes in conjunction with an accelerator pedal is arranged in the intake passage of the engine, and an electric throttle valve is arranged in the intake passage upstream of the mechanical throttle valve. It is well known that when slippage occurs in the drive wheels during start-up acceleration of the vehicle, the opening of the electric throttle valve is controlled to reduce the output torque of the engine to suppress the slippage of the wheels. ing.

Further, as the engine output increases, there is a problem that the intake air amount changes greatly even when the throttle valve is slightly opened, and the intake air amount does not change linearly with the throttle opening. Even in such a case, by providing the electric throttle valve as described above, the change characteristic of the throttle opening and the intake air amount can be made to have a linear relationship, and the driving feeling of the vehicle can be improved.

The electric throttle valve is usually
Although it is designed to be driven by a stepping motor as an actuator, considering the so-called step-out phenomenon of this stepping motor, its fully closed opening cannot be made too small, and therefore, in the idle region of the engine, the The fully closed opening of the throttle valve is set larger than that of the mechanical throttle valve.

[0005]

When processing evaporative fuel that evaporates in the fuel tank, generally, the evaporative fuel is adsorbed by a canister and the adsorbed evaporative fuel is used in a predetermined operating region of the engine. The intake system downstream of the throttle valve is purged and processed. The operating area of the engine for purging the evaporated fuel of the canister is usually a non-idle area, but if the evaporated fuel is not purged even in the idle area due to higher engine output, increase in the evaporated fuel purge amount, etc. There is a risk that the fuel cannot be processed and the canister overflows.

However, in the idle region of the engine, the throttle valve is fully closed and the intake negative pressure generated on the downstream side of the throttle valve is large. Therefore, if the evaporated fuel is purged in this state, the purge amount becomes excessive and idle stability is improved. And the emission property is impaired.

The present invention has been made in view of the above points, and an object of the present invention is to make good use of the opening characteristic of the electric throttle valve described above.
The purpose of the present invention is to be able to purge evaporated fuel while preventing the purge amount from becoming excessive even when the engine is idle.

[0008]

In order to achieve the above object, the invention of claim 1 purges the evaporated fuel into the intake passage upstream of the mechanical throttle valve and downstream of the electric throttle valve. did.

Specifically, in the present invention, a mechanical throttle valve disposed in the intake passage and opened / closed in conjunction with an accelerator pedal, and an electric throttle valve disposed in the intake passage upstream of the mechanical throttle valve. In the idle region, the fully closed opening degree of the electric throttle valve is set to be larger than the fully closed opening degree of the mechanical throttle valve, and the evaporated fuel supply passage for supplying the evaporated fuel of the fuel supply system to the intake system is provided. It is premised on an engine equipped with the evaporated fuel processing means.

The characteristic point is that the downstream end of the evaporated fuel supply passage is opened in the intake passage between the mechanical throttle valve and the electric throttle valve.

[0011]

With the above construction, in the invention of claim 1, when the engine is in the idle region, the fully closed opening degree of the electric throttle valve is set larger than that of the mechanical throttle valve. The intake negative pressure is smaller than the intake negative pressure on the downstream side of the mechanical throttle valve. Further, since the downstream end of the evaporated fuel supply passage is opened in the intake passage between the two throttle valves, the evaporated fuel can be purged and processed without becoming excessive even when the engine is idle.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the overall configuration of an embodiment of the present invention. Reference numeral 1 denotes a V-type 6-cylinder engine mounted on a vehicle, which has three cylinders 3, 3, ... In the left and right banks 2L, 2R, respectively. In this engine 1, cylinder heads 5L and 5R are assembled on the upper surface of a cylinder block 4 having a substantially V-shaped cross section, and a piston 6 is reciprocally fitted in each cylinder 3 and the top of the piston 6 is inserted. A combustion chamber 7 is formed in the cylinder 3 surrounded by the surface and the lower surface of the cylinder head 5.

Reference numeral 8 denotes an intake passage for supplying intake air to the combustion chamber 7 of each cylinder 3, and reference numeral 9 denotes an intake valve for opening and closing an opening end of the intake passage 8 to the combustion chamber 7, which is upstream of the intake passage 8. From the air flow meter 10 for detecting the intake air amount, and the electric throttle valve 1 for driving the stepping motor 11 as an actuator to throttle and open the intake passage 8.
2, a mechanical throttle valve 14 that throttles and opens the intake passage 8 in conjunction with driving of an accelerator pedal 13, and a pair of surge tanks 1 provided for each bank 2L, 2R.
5L, 15R and injectors 16, 16, ... Injecting and supplying fuel to the intake passage 8 are provided. And
In the idle region of the engine, due to the step-out phenomenon of the stepping motor 11, the fully closed opening of the electric throttle valve 12 is set to be larger than the fully closed opening of the mechanical throttle valve 14 as shown in FIG.

Reference numeral 18 denotes an exhaust passage for discharging the exhaust gas in the combustion chamber 7, and reference numeral 19 denotes an exhaust valve for opening and closing the opening end of the exhaust passage 18 to the combustion chamber 7.

Further, 21 is a fuel tank for storing the fuel of the engine, 22 is an evaporated fuel processing means for supplying the evaporated fuel in the fuel tank 21 to the intake system, and the evaporated fuel processing means 22 is the fuel tank 21. The check valve 2 has an evaporative fuel supply passage 23 opening to the upper part of the inside thereof, and in the middle of the evaporative fuel supply passage 23, a check valve 2 for preventing backflow of the evaporated fuel is provided.
4, a canister 25 located downstream of the canister 25 for adsorbing the evaporated fuel, and a canister 25 located downstream of the canister 25.
A solenoid valve 26 is provided for opening and closing 3 to purge evaporated fuel from the canister 25 into the intake system. A feature of the present invention is that the vaporized fuel supply passage 23 is
The downstream end of is opened to the intake passage 8 between the mechanical throttle valve 14 and the electric throttle valve 12 on the upstream side thereof.

The solenoid valve 26 in the vaporized fuel supply passage 23 is controlled to open and close by receiving a signal from the control unit 31. At least the intake air amount signal from the air flow meter 10, the crank angle signal from a distributor (not shown), and the water temperature signal of the cooling water temperature of the engine 1 are input to the control unit 31. Then, in the control unit 31, the purge area of the evaporated fuel is set as a map from the engine load based on the intake air amount signal and the engine speed calculated based on the crank angle signal, and this purge area is shown in FIG. As shown, the engine 1 is in the low to medium load region including the idle region,
When the operating region of the engine 1 is in the purge region and the temperature of the cooling water is, for example, 40 ° C. or higher, the solenoid valve 26 is opened to purge the fuel vapor adsorbed by the canister 25 into the intake system. It has become.

Therefore, in the above embodiment, the opening / closing control of the electric throttle valve 12 is performed as follows.
That is, for example, when slippage occurs in the drive wheels at the time of starting acceleration of the vehicle or the like, the opening degree of the electric throttle valve 12 is controlled in the decreasing direction by the stepping motor 11 which receives the control signal of the control unit 31. The output torque of No. 1 is reduced and wheel slip is suppressed.

Further, as shown in FIG. 2, the electric throttle valve 12 has an opening degree of the accelerator pedal 13 (accelerator opening degree).
In the small idle region, the opening of the electric throttle valve 12 is larger than the opening of the mechanical throttle valve 14, and the opening of the electric throttle valve 12 is smaller than the opening of the mechanical throttle valve 14 as the accelerator opening increases. Controlled to be. As a result, the driving feeling of the vehicle is improved by making the change characteristics of the throttle opening and the intake air amount into a linear relationship.

On the other hand, the operating region of the engine 1 is determined based on the intake air amount detected by the air flow meter 10 and the engine speed obtained from the crank angle signal, and the operating region is a purge region including an idle region (see FIG. (See 4)
When the temperature of the cooling water becomes 40 ° C. or higher, the solenoid valve 26 is opened, and the evaporated fuel evaporated in the fuel tank 21 and adsorbed in the canister 25 is purged into the intake system via the evaporated fuel supply passage 23. Is processed.

In this case, in the intake passage 8 of the engine 1, the electric throttle valve 12 is downstream, the mechanical throttle valve 14 is upstream, that is, the point A between the throttle valves 12 and 14, and the mechanical throttle valve 14 is downstream. Comparing the intake negative pressures generated by and, respectively, as shown in FIG. 3, when the engine 1 is in the idle region, the fully closed opening degree of the electric throttle valve 12 is set larger than that of the mechanical throttle valve 14. , These throttle valves 12, 14
The intake negative pressure at the point A between them is smaller than the intake negative pressure at the point B on the downstream side of the mechanical throttle valve 14. Since the downstream end of the evaporated fuel supply passage 23 is opened in the intake passage 8 at the point A between the throttle valves 12 and 14, the solenoid valve 26 is opened in the idle region of the engine 1.
Even when the evaporative fuel is purged by opening the valve, it is possible to perform the purging process while preventing the evaporative fuel from being excessively purged and impairing the idle stability and the emission property.

In the above embodiment, the evaporated fuel in the fuel tank 21 is processed, but the invention can be applied to the case where the evaporated fuel generated in other fuel supply system is processed.

[0022]

As described above, according to the first aspect of the invention, the mechanical throttle valve interlocking with the accelerator pedal and the electric throttle valve located upstream of the mechanical throttle valve are arranged in the intake passage, and the idle region is provided. For an engine in which the fully closed opening degree of the electric throttle valve is larger than that of the mechanical throttle valve, the downstream end of the evaporated fuel supply passage that supplies the evaporated fuel of the fuel supply system to the intake system is connected to the mechanical throttle valve. By opening the intake passage between the electric throttle valve and the electric throttle valve, it is possible to purge evaporated fuel into the intake passage between both throttle valves, where the intake negative pressure is lower than the intake negative pressure on the downstream side of the mechanical throttle valve, Evaporative fuel can be purged and processed when the engine is idle, and it is prevented that the evaporated fuel is excessively purged and idle stability and emission performance are impaired. Rukoto can.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing an opening characteristic of each throttle valve with respect to an accelerator opening.

FIG. 3 is a characteristic diagram showing characteristics of a change in intake negative pressure between a mechanical throttle valve downstream side and both throttle valves.

FIG. 4 is a diagram showing a purge region for evaporated fuel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 engine 8 intake passage 11 stepping motor 12 electric throttle valve 13 accelerator pedal 14 mechanical throttle valve 21 fuel tank 22 evaporated fuel processing means 23 evaporated fuel supply passage 25 canister 26 solenoid valve 31 control unit

Claims (1)

[Claims] 1. A mechanical throttle valve disposed in an intake passage, which opens and closes in conjunction with an accelerator pedal, and an electric throttle valve disposed in an intake passage upstream of the mechanical throttle valve. The fully closed opening of the electric throttle valve is set to be larger than the fully opened opening of the mechanical throttle valve, and an evaporated fuel processing means having an evaporated fuel supply passage for supplying evaporated fuel of the fuel supply system to the intake system is provided. In the above engine, the evaporated fuel processing apparatus for an engine, wherein a downstream end of the evaporated fuel supply passage is opened in an intake passage between the mechanical throttle valve and the electric throttle valve.