JPH0444850Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an ignition timing control device for an internal combustion engine that corrects ignition timing controlled based on engine operating conditions in accordance with the properties of fuel.

<Prior art> In a conventional ignition timing control device for an internal combustion engine, a map of ignition timing control values (ignition advance angle values) corresponding to engine speed and load, which are parameters of engine operating conditions, is stored in advance. The ignition timing was then controlled based on this
(See Publication No. 49369, etc.)

<Problems to be solved by the invention> However, the above maps are generally created on the assumption that regular gasoline will be used as fuel, so if high-octane gasoline or alcohol-containing gasoline is used, the breath However, there has been a problem in that poor drivability such as backfire failure may occur.

In view of these conventional problems, the present invention aims to improve drivability by accurately determining the properties of the fuel used and correcting the ignition timing accordingly.

<Means for solving the problem> For this reason, the present invention, as shown in FIG. a canister that guides evaporated fuel in the fuel tank and closes the purge passage of the canister that processes the evaporated fuel when the tank is full.
A purge passage closing means, a vapor pressure detection means for detecting the fuel vapor pressure in the fuel tank after the purge passage is closed for a predetermined time, a fuel temperature detection means for detecting the fuel temperature in the fuel tank at that time, and the detected fuel vapor pressure. and fuel property estimating means for estimating the properties of the fuel from the fuel temperature and the fuel temperature.

<Function> In other words, it takes advantage of the fact that the temperature-vapor pressure characteristics differ depending on the properties of the fuel, specifically high-octane gasoline, regular gasoline, alcohol-containing gasoline, etc., to adjust the fuel vapor pressure (lead vapor pressure) in the fuel tank. The system detects the amount of fuel being used, estimates the fuel being used based on the fuel vapor pressure and fuel temperature, and corrects the ignition timing according to the properties of the fuel, thereby improving drivability.

In addition, when estimating the properties of the fuel, the full state of the fuel tank is detected, and when the full tank is detected, the purge passage of the canister is closed to seal the fuel tank, and after a predetermined time, the fuel vapor in the fuel tank is detected. By detecting pressure and fuel temperature, it is possible to particularly improve the detection accuracy of fuel vapor pressure and the estimation accuracy of fuel properties.

<Example> An embodiment of the present invention will be described below.

In FIG. 2, air is taken into the engine 1 through an air cleaner 2, an intake duct 3, a throttle chamber 4, and an intake manifold 5. As shown in FIG.

An air flow meter 6 is provided in the intake duct 3 to detect the intake air flow rate. The throttle chamber 4 is provided with a throttle valve 7 that operates in conjunction with an accelerator pedal (not shown) to control the flow rate of intake air. The intake manifold 5 is provided with an electromagnetic fuel injection valve 8 for each cylinder, and the fuel is fed under pressure from a fuel pump 10 provided in a fuel tank 9 and controlled to a predetermined pressure by a pressure regulator (not shown). Fuel is injected and supplied to the engine 1.
The control of the fuel injection amount is calculated by a control unit 11 with a built-in microcomputer based on an intake air flow rate Q detected by an air flow meter 6 and a signal from a crank angle sensor 12 built into a distributor 15, which will be described later. Based on the engine speed N, the basic fuel injection amount Tp=K・
Q/N (K is a constant) is calculated, this is corrected appropriately to set the fuel injection amount, and a drive pulse signal with a pulse width corresponding to this is given to the fuel injection valve 8 in synchronization with the rotation of the engine 1. To do something.

Each cylinder of the engine 1 is provided with an ignition plug 13, and a high voltage generated by an ignition coil 14 is sequentially applied to these via a distributor 15, thereby igniting a firework and igniting the air-fuel mixture. Burn it. Here, the timing at which high voltage is generated in the ignition coil 14 is controlled via a power transistor 14a attached thereto. Therefore, the ignition timing is controlled by controlling the on/off timing of the power transistor 14a using an ignition signal from the control unit 11.

In the control unit 11, the optimum ignition timing (ignition advance angle) is determined by arithmetic processing based on various input signals and data on the ROM and PAM, and the ignition signal is sent to drive the ignition coil 14 at that timing. power transistor 14a.

Specifically, first, the ignition advance angle ADV determined according to the engine speed N and the basic fuel injection amount (load) Tp is searched from the advance angle map on the ROM. Next, the ignition advance angle ADV is corrected as necessary to determine the final ignition advance angle ADV. Ignition advance angle
When ADV is determined, the reference signal from the crank angle sensor 12 is, for example, 80° before compression top dead center.
If the signal is output at
Each time a position signal is input, the count value is subtracted by one, and when the count value reaches 0, an ignition signal is output to the power transistor 14a.

When controlling the ignition timing, the ignition timing is corrected according to the properties of the fuel used. This correction is
It is a good idea to prepare a plurality of advance angle maps in advance in the ROM, such as for high-octane gasoline, regular gasoline, alcohol-containing gasoline, etc., and select an appropriate advance angle map according to the properties of the fuel used.

The following means are provided for determining fuel properties. That is, a signal from a fuel gauge 16 consisting of a float and a potentiometer that detects the remaining amount of fuel in the fuel tank 9 is input to the control unit 11. A normally open solenoid valve 19 is located in the middle of the purge passage 18 of the canister 17 that guides the evaporated fuel in the fuel tank 9 and processes the evaporated fuel.
By closing this electromagnetic valve 19 in response to a signal from the control unit 11, the fuel tank 9 can be brought into a sealed state. In order to detect the fuel vapor pressure in the fuel tank 9, a pressure sensor 2 is provided as vapor pressure detection means.
0 and sends that signal to control unit 1.
1 has been entered. Further, in order to detect the temperature of the fuel in the fuel tank 9, a temperature sensor 21 is provided as a fuel temperature detection means, and its signal is inputted to the control unit 11. This temperature sensor 21
As a solution, a thermistor used as a liquid level sensor for warning of remaining amount may be used.

Then, the microcomputer built into the control unit 11 performs processing according to the flowchart shown in FIG. 3 to select an advance angle map.

Explaining according to the flowchart in Figure 3,
First, in step 1 (indicated by S1 in the figure, the same applies hereinafter), it is determined whether the fuel tank 9 is full (that is, immediately after refueling) based on the signal from the fuel level gauge 16.

Only when the tank is full, proceed to the flow below and proceed to step 2.
The solenoid valve 19 is turned on and closed to close the purge passage 18 of the canister 17, thereby sealing the fuel tank 9. Then, in step 3, the system waits for a predetermined time. Then, in step 4, the fuel vapor pressure in the fuel tank 9 is detected based on the signal from the pressure sensor 20, and at the same time, in step 5, the fuel temperature in the fuel tank 9 at that time is detected based on the signal from the temperature sensor 21. do. After the detection, in step 6, the solenoid valve 19 is turned off and opened.

Here, the characteristics of fuel vapor pressure with respect to fuel temperature differ among high-octane gasoline A, regular gasoline B, alcohol-containing gasoline C, etc., as shown in FIG. 4. Therefore, the fuel used can be estimated from the fuel vapor pressure and fuel temperature.

Therefore, in step 7, the type of gasoline is known by referring to the vapor pressure map that stores the type of gasoline according to the fuel vapor pressure and fuel temperature, and in step 8, the advance angle map corresponding to the type is selected. and set. The code for the advance angle map selected here is written into a RAM with a backup power supply and is stored until the next time the tank is refueled.

Therefore, when searching for the ignition advance value from the advance angle map based on the engine operating condition, first select the advance angle map that corresponds to the code stored in the RAM, and then search from this advance angle map. It is.

Incidentally, the step 1 part, together with the fuel level gauge 16, corresponds to the full tank detection means, the step 2 part, together with the solenoid valve 19, corresponds to the canister purge passage closing means, and the step 4 part, together with the pressure sensor 20, corresponds to the steam detection means. This corresponds to a pressure detection means, and the step 5 corresponds to a fuel temperature detection means together with the temperature sensor 21.
Step 7 corresponds to fuel property estimation means,
The step 8 corresponds to the ignition timing correction means.

<Effects of the invention> As explained above, according to the invention, the properties of the fuel being used are accurately determined and the ignition timing is corrected accordingly, thereby eliminating the occurrence of poor drivability due to differences in fuel properties. This has the effect of preventing In addition, when estimating the properties of fuel from fuel vapor pressure and fuel temperature, when the fuel tank is full, the purge passage of the canister is closed to seal the fuel tank, and after a predetermined time, the fuel vapor inside the fuel tank is By detecting pressure and fuel temperature,
The effect is that the estimation accuracy of fuel properties can be significantly improved.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the configuration of the present invention;
The figure is a system diagram showing one embodiment of the present invention, FIG. 3 is a flowchart, and FIG. 4 is a temperature-vapor pressure characteristic diagram of various gasolines. DESCRIPTION OF SYMBOLS 1... Engine, 9... Fuel tank, 11... Control unit, 13... Spark plug, 14... Ignition coil, 16... Fuel level gauge, 17... Canister, 19... Solenoid valve, 20... ...Pressure sensor, 2
1...Temperature sensor.

Claims (1)

[Scope of Claim for Utility Model Registration] An ignition timing control device for an internal combustion engine that controls ignition timing based on engine operating conditions, which includes ignition timing correction means for correcting ignition timing according to the properties of fuel, a full tank detection means for detecting a full state of the fuel tank; a canister purge passage closing means for closing a purge passage of a canister that guides and processes evaporated fuel in the fuel tank when the full tank is detected; and a canister purge passage closing means for a predetermined period of time. Vapor pressure detection means detects the fuel vapor pressure in the fuel tank after closing, fuel temperature detection means detects the fuel temperature in the fuel tank at that time, and the properties of the fuel are determined from the detected fuel vapor pressure and fuel temperature. An ignition timing control device for an internal combustion engine, comprising fuel property estimating means for estimating fuel properties.