JPS6198956A - High temperature restart control method of electronically controlled engine - Google Patents

Abstract

PURPOSE:To prevent an engine from worsening its start due to evaporation of fuel when the engine is restarted at a high temperature, by constituting the engine such that fuel vapor attractively adhering to a canister is supplied to the downstream of a throttle valve when the engine is restarted at the high temperature with a temperature of fuel in a preset value or more further with air-fuel ratio in a lean condition. CONSTITUTION:When an engine is started, an EFI computer 30, deciding whether or not an idle switch contained in a throttle sensor 36 is turned on, decides, when the decision is that the idle switch is turned on, whether or not a temperature of fuel in a delivery pipe 50 detected by a fuel temperature sensor 52 is in a preset value (about 70 deg.C) or more. When the decision is YES, that is, the decision is when the engine is restarted at a high temperature, a negative pressure selector valve 46 is switched to a direction connection a canister 44 with a purge port 20A in an intake manifold 20. In this way, the engine, executing the purge for the intake manifold 20, enables fuel insufficient due to evaporation to be supplemented with fuel in the canister 44 when the engine is restarted.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a high temperature restart control method for an electronically controlled engine, and in particular has a canister for adsorbing fuel vapor suitable for use in a self-help vehicle gasoline engine equipped with an electronically controlled fuel injection device. The present invention relates to a high temperature restart control method for an electronically controlled engine in which fuel vapor adsorbed in the canister is supplied upstream of a throttle valve during normal operation.

[Conventional technology]

In gasoline engines, especially automobile gasoline engines equipped with electronically controlled fuel injection devices, when the temperature is high, the temperature of the gasoline and the area around the injector rises, and a portion of the fuel injected from the injector turns into steam, which is necessary for starting. In some cases, there was a shortage of sufficient fuel, resulting in failure to restart at high temperature. On the other hand, conventionally, if fuel vapor that is constantly generated from a fuel tank containing gasoline is released into the atmosphere,
To prevent this from polluting the atmosphere and wasting fuel, the system is equipped with a canister to adsorb fuel vapor, and during normal operation, the fuel vapor adsorbed by the canister is supplied to the upstream side of the throttle valve. Gasoline engines are known.

[Problems to be solved by the invention]

However, in the past, no proposal has been made that combines the above-mentioned improvement in high restartability with third-level control of fuel vapor adsorbed in the canister, and each measure has been taken independently, which has been wasteful. Furthermore, in Japanese Patent Application Laid-Open No. 57-129247, by controlling the opening and closing of a solenoid valve disposed in a discharge passage connecting a canister to an intake passage of a carburetor according to the output of an air-fuel ratio sensor,
A fuel lid designed to prevent the mixture supplied to the engine from becoming overrich. Although a scattering prevention device has been proposed, it has a different purpose and configuration from the present invention, and does not improve high-temperature restartability like the present invention.

OBJECTIVE OF THE INVENTION 1 The present invention has been made to solve the above-mentioned conventional problems, and it is possible to improve starting failures caused by fuel evaporation during high-temperature restarts by using fuel vapor adsorbed in the canister. The present invention aims to provide a high temperature restart control method for an electronically controlled engine. [Means for Solving the Problems] The present invention has a canister for adsorbing fuel vapor, and during normal operation, the fuel vapor adsorbed in the canister is supplied upstream of the throttle valve. The high-temperature restart control method for an electronically controlled engine, as summarized in Figure 1, includes a procedure for detecting that it is starting, a procedure for detecting that the fuel temperature is above a set value, and a procedure for detecting that the air-fuel ratio is A procedure for detecting a lean state, and when restarting at Ij4 temperature where the fuel temperature is higher than the set value and when the air-fuel ratio is in a lean state, the fuel vapor adsorbed in the canister is transferred to the throttle valve. The above objective is achieved by including a downstream supply procedure. (Function) In the present invention, when the fuel temperature is higher than the set value during a high-temperature restart and the air-fuel ratio is in a lean state, the fuel vapor adsorbed in the canister is supplied downstream of the throttle valve. Therefore, by using the fuel vapor adsorbed in the canister, it is possible to improve starting failures caused by fuel evaporation during high-temperature restart.

【Example】

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an electronically controlled fuel injection engine for automobiles to which the present invention is applied will be described in detail with reference to the drawings. In this embodiment, as shown in FIG. 2, the air taken in through the air cleaner 12 is metered by the air meter 14, and then passes through the throttle body 16 in which the throttle valve 18 is disposed, and then the air is taken into the intake air. The fuel is inhaled into a combustion chamber (not shown) of the engine 10 together with fuel intermittently injected from an injector 22 disposed in the manifold 20 . Exhaust gases combusted and formed in the combustion chamber are collected in an exhaust manifold 24 and then discharged through a three-way catalyst 26. An electronic fuel injection computer (hereinafter referred to as an EFI computer) 30 controls the injector 22 according to the engine rotation speed calculated from the intake air flow rate measured by the air meter 14 and the primary signal of the ignition coil 32.
The basic fuel injection amount to be injected at one time is calculated from The effective injection time is calculated by correcting the water temperature sensor 38 that detects the water temperature and the output of an oxygen concentration sensor (hereinafter referred to as 02 sensor) 40 disposed downstream of the exhaust manifold 24, and the effective injection time is The injector 22 is opened for a certain amount of time to inject an appropriate amount of fuel. In Figure 2, 33
is your destination user. For example, as shown in detail in FIG. 3, this EFI computer 30 includes a central processing unit (hereinafter referred to as CPU) 30A that performs various calculation processes, and a random access unit that temporarily stores calculation data, input data, etc. Memories (hereinafter referred to as RAM) 30B and 30C, and read-only memory (hereinafter referred to as ROM) 30D for pre-storing data necessary for calculations, $1 control programs, etc.
and the air flow meter 14. Intake temperature sensor 34, throttle sensor 36, water temperature sensor 38.02 sensor 40
, an analog signal input from the downstream fuel temperature sensor 52, etc., for converting it into a digital signal and importing it.
Digital converter (hereinafter referred to as A/D converter)
30E, the signals input from the central ignition coil 32, etc. are waveform-shaped and directly taken in, and the CPU 30A
An input/output boat (hereinafter referred to as I1) outputs a control signal to the injector 22 and the rear negative pressure switching valve 46 according to the calculation results
It consists of a bus 30F, called a 0 port, and a common bus 30G, which connects each component and transfers data and instructions. The electronically controlled fuel injection engine 10 is further equipped with a canister 44 for adsorbing fuel vapor generated from a fuel tank 42, and the fuel vapor adsorbed in the canister 44 is transferred to a three-way negative pressure switch. The purge boat 16A1 or the throttle valve 1 formed upstream of the throttle valve 18 of the throttle body 16 via the valve 46
The air is supplied to a barge boat 20A formed in the intake manifold 20 downstream from the intake manifold 8. Further, a fuel temperature sensor 52 for detecting fuel temperature is disposed in a delivery vibe 50 for supplying fuel pressurized by the fuel pump 48 from the fuel tank 42 to each injector 22. The operation of the embodiment will be explained below. First, during normal operation, a control signal output from the EFr computer 30 causes the negative pressure switching valve 46 to switch between the canister 44 and the barge boat 16A of the throttle body 16.
It is open in the direction of communication. Therefore, in this state, when negative pressure is generated in the intake pipe due to engine rotation, the fuel vapor adsorbed in the canister 44 is supplied to the upstream side of the throttle valve 18, as in the conventional case. At this time, if a predetermined feedback III til1 condition is satisfied, the amount of fuel injected from the injector 22 is feedback-controlled in accordance with the rich-lean signal output from the 02 sensor 40. On the other hand, control at the time of starting is executed according to a flowchart as shown in FIG. That is, first, in step 110, it is determined whether the idle switch included in the throttle sensor 36 is on. If the determination result is positive, that is, it is determined that the throttle valve 18 is closed and the engine is in an idling state. In some cases, the process proceeds to step 112, where it is determined whether the fuel temperature within the delivery vibe 50 detected by the fuel temperature sensor 52 is equal to or higher than the setting 1iaT, for example, 70'C. If the determination result is positive, that is, if it is determined that a high-temperature restart is occurring, the process proceeds to step 114, and the negative pressure switching valve 46 is moved in the direction of communicating the canister 44 and the barge boat 2OA of the intake manifold 20. Then, the intake manifold 20 is purged (hereinafter referred to as idle purge). Then step 116
Then, it is determined whether the output of the 02 sensor 40 has become rich. As shown in FIG. 5, the output of the 02 sensor 40 changes from lean to rich with the elapsed time after the engine starts, and it is considered lean until the output of the 02 sensor 40 reverses to rich. can be judged. If the determination result in step 116 is negative,
That is, when it is determined that the output of the 02 sensor 40 is extremely lean, the process returns to step 114 and continues the idle purge. On the other hand, if the determination results in steps 110 and 112 are negative, or if the determination results in step 116 are positive, the process proceeds to step 118, in which the negative pressure switching valve 46 is switched between the canister 44 and the throttle. The barge boat 16A of the body 16 is switched to the communication direction, the idle purge is stopped, and this routine is ended. This allows normal purging and prevents fuel from flowing out. In this way, by replenishing the fuel in the canister 44 that is insufficient due to evaporation at the time of high-temperature restart,
Island heat restartability is improved. In this embodiment, a high-temperature restart is detected when the idle switch is on and the fuel temperature in the delivery pipe is higher than a set value. It can be detected easily and accurately. Note that the method for detecting the time of high temperature restart is not limited to this. Although the above embodiments apply the present invention to an electronically controlled fuel injection engine for automobiles, the scope of application of the present invention is not limited thereto, and it is possible to apply the present invention to general electronically controlled engines as well. it is obvious. (Effect of the Invention 1 As explained above, according to the present invention, it is possible to replenish fuel that is insufficient due to evaporation during a high temperature restart by using fuel vapor adsorbed in the canister. Therefore, during a high temperature restart This has an excellent effect in that it can improve starting problems caused by fuel evaporation.

[Brief explanation of drawings]

Fig. 1 is a flowchart showing the gist of the high temperature restart control method for an electronically controlled engine according to the present invention, and Fig. 2 shows the configuration of an embodiment of an electronically controlled fuel injection engine for a self-driving vehicle to which the present invention is adopted. , a plan view including a partial block diagram and a sectional view;
FIG. 3 is a block Ii1 diagram showing the configuration of the electronic fuel injection computer used in the embodiment, FIG. 4 is a flowchart showing the procedure for restart control at high temperature in the embodiment, and FIG. , is a diagram showing an example of a state of change in the output of the oxygen concentration sensor in the embodiment. DESCRIPTION OF SYMBOLS 10... Engine, 16... Throttle body, 16A... Barge boat, 18... Throttle valve, 20... Intake manifold, 2OA... Barge boat, 22... Injector, 24...・Exhaust manifold, 30...electronic fuel injection (EFI) converter,
36... Throttle sensor, 40... Oxygen concentration (02) sensor, 42... Fuel tank, 44... Canister, 46... Negative pressure switching point, 50... Delivery vibe, 52. ...Fuel temperature sensor.

Claims (1)

[Claims] (1) A high-temperature restart control method for an electronically controlled engine that has a canister for adsorbing fuel vapor, and during normal operation, the fuel vapor adsorbed by the canister is supplied upstream of a throttle valve, A procedure for detecting that it is time to start, a procedure for detecting that the fuel temperature is at least a set value, a procedure for detecting that the air-fuel ratio is in a lean state, and a procedure for detecting that the fuel temperature is at the set value or more. A high temperature restart control for an electronically controlled engine, comprising: supplying fuel vapor adsorbed in the canister to the downstream side of a throttle valve when the air-fuel ratio is in a lean state at the time of startup. Method.