JPS6240548B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to a device for controlling ignition timing at the time of starting an internal combustion engine.

<Background Art> Ignition timing control devices that electronically advance or retard ignition timing in response to operating status signals such as the intake air amount of an engine have been known. In this method, ignition timing data corresponding to the engine operating state is determined in advance, the ignition timing to be controlled is read based on the detected engine operating state, and the output signal is supplied to the power transistor of the ignition device.

However, when cranking the engine, i.e. starting, the ignition timing data used for normal ignition timing control is not used, but as shown in Figure 1, the ignition timing data during cranking is determined separately for the engine temperature, for example, the engine cooling water temperature. In particular, the ignition timing is advanced at low temperatures to improve startability.

Such a starting ignition timing control device is disclosed in, for example, Japanese Patent Application Laid-open No. 139970/1983.

That is, a control unit 1 such as a microcomputer receives a switch signal from a starter switch 2 that detects engine starting, a water temperature signal from a cooling water temperature sensor 3 that detects engine temperature, and a crank angle sensor 4 that detects engine rotation speed. A crank angle signal of , and an intake air amount signal from an air flow meter 5 that detects the amount of intake air are input, respectively.

The control unit 1 determines the basic pulse width of the fuel injection valve opening/closing duty according to the basic injection amount calculated in advance according to the intake air amount and engine rotational speed, and determines the ignition during normal operation according to this and the engine rotational speed. Store the timing data in ROM. Then, the ignition timing data is read based on the actual detection signals of each of the detection means 2 to 5, and an optimum ignition command signal is output to the power transistor 7 of the ignition device 6 to turn it on, and the spark plug 8 ignites. In FIG. 2, 9 is an ignition coil, 10 is a distributor, and 11 is a battery.

At the time of starting (during cranking) when the starter switch 2 is turned on, the ignition timing control routine at the time of starting is inserted into the normal operation routine. That is, the advance angle value for the cooling water temperature is separately determined as shown in FIG. 1, and the ignition timing is advanced especially at low temperatures to improve startability.

However, with this kind of ignition timing control at startup that depends only on the coolant temperature, during low-temperature starts with a large amount of advance, the engine may stop after the initial explosion before it can fully detonate and run on its own. . This is because the earlier the cranking speed is low and the engine is unstable, the ignition timing is too early, and the combustion gas pressure acts strongly in the reverse direction through the piston.

On the other hand, as seen in Japanese Unexamined Patent Publication No. 137359/1983, the advance angle is controlled to be smaller as the engine rotational speed during cranking becomes lower, that is, in the early stages of startup, to prevent the engine from stopping after the first explosion. However, the advance angle was too small, making the first explosion difficult and causing another problem: it took a long time to start.

<Object of the Invention> In view of the above-mentioned conventional inconveniences, an object of the present invention is to reliably obtain an initial explosion at the time of starting an engine, while preventing the engine from stopping after the initial explosion.

<Structure of the Invention> In order to achieve the above object, the present invention includes a means for detecting the start of the engine, a means for detecting the engine temperature, a means for detecting the engine rotational speed, and a means for detecting the engine rotational speed in response to input signals from each of the above-mentioned means. and an ignition timing control means that outputs an ignition command signal to the ignition system to reduce the ignition advance value in response to a rise in engine temperature and in response to an increase in engine rotational speed at the time of starting, so that the ignition advance is increased as the engine temperature is lower. While the conventional technology of increasing the ignition angle value is followed to ensure the first explosion, the engine is stopped after the first explosion by gradually decreasing the ignition advance value so that the cranking speed increases and the complete explosion becomes stable. prevent.

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

In the configuration diagram of FIG. 3, a starter switch 21 is a means for detecting engine starting when turned on, and the on signal is inputted to an ignition timing control means 22.

The crank angle sensor 23 is a means for detecting the engine rotational speed, and the water temperature sensor 24 is a means for detecting the engine temperature, in this case the engine cooling water temperature. is input.

The ignition timing control means 22 is constituted by, for example, a microcomputer consisting of an input/output processing unit, a central processing unit, and a storage unit, and the ignition timing control means 22 is configured with a microcomputer consisting of, for example, an input/output processing unit, a central processing unit, and a storage unit. The assigned ignition advance value CRADV at startup and the ignition advance rotation correction coefficient α assigned in advance to the ROM 22b according to the engine speed as shown in FIG. Read out based on cranking speed. Then, the ignition timing determining means 22c calculates the product (CRADV×α) of the read ignition advance value and the ignition advance rotation correction coefficient, and uses this as the ignition advance value CRADV·RE to be actually controlled. For example, output to a power transistor.

Here, the ignition advance value is stored in the ROM 22a so that it becomes smaller as the cooling water temperature rises, and as the engine rotation speed increases, the ignition timing correction coefficient (≦1) becomes smaller (the correction factor becomes larger). The ignition advance angle value is stored in the ROM 22b so as to be small.

Therefore, when the engine is started at a low temperature, the cooling water temperature is lowest and the engine rotational speed is lowest during cranking, so the actual ignition advance value CRADV·RE calculated by the ignition timing determining means 22c is
CRADV×α becomes the largest, that is, it becomes the most advanced and the first explosion becomes easier to obtain. When some cylinders are ignited during cranking and the first explosion occurs, the engine speed increases. Since the ignition advance rotation correction coefficient α becomes smaller by this increase in engine speed, the ROM22
The ignition advance value CRADV, which depends only on the cooling water temperature stored in a, is corrected in the direction of gradually decreasing the ignition advance value CRADV (the cooling water temperature hardly changes during cranking, so CRADV also does not change), and as a result, the initial Ignition after detonation occurs too early and no combustion gas pressure is applied in the reverse direction, which prevents the engine from stopping.

This operation is shown in FIG. 6 as a flowchart.

As a result of performing the above ignition timing control at a cooling water temperature of -30° C., as shown in FIG. 7, the initial explosion failure was eliminated and the time required to reach a complete explosion (starting time) was significantly shortened. In the figure, the x mark indicates a failure to start, the ○ mark indicates the time it took to reach the first detonation, and the ● mark the time it took to complete detonation.

In the above embodiment, the base may be determined as the ignition advance value corresponding to the engine rotation speed and corrected by the cooling water temperature, or the base may be calculated as a three-dimensional ignition advance value corresponding to the engine rotation speed and the cooling water temperature. It goes without saying that the map may be memorized and read.

In the above embodiment, only the ignition timing control at the time of starting has been described, but after the completion of starting, the routine can be shifted to the normal ignition timing control routine, as in the conventional case.

<Effects of the Invention> As described above, according to the present invention, the lower the engine temperature, the more the ignition advance is advanced to easily ensure the first explosion during cranking, and then as the engine speed increases, the ignition advance value is increased. Since the complete explosion is made stable by making the size smaller, the initial explosion and subsequent complete explosion are reliably obtained, which prevents the engine from stopping after the initial explosion and significantly improves startability. Since starting is thus ensured, fuel efficiency can be improved, and the battery and starter can be made smaller and lighter, leading to cost reductions.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the ignition timing characteristics according to the cooling water temperature of a conventional device, FIG. 2 is a system diagram showing an example of the conventional device, and FIG. 3 is a block diagram showing the configuration of an embodiment of the present invention. Figure 4 is the same as above.
A graph showing the relationship between the cooling water temperature and the ignition advance value stored in the ROM, Figure 5 is a graph showing the relationship between the engine speed and the ignition advance rotation correction coefficient also stored in the ROM, and Figure 6 is the graph shown above. FIG. 7 is a flowchart showing the effects of the embodiment, and a graph showing the results of experiments conducted using the present invention. 6...Ignition device, 21...Starter switch, 2
2...Ignition timing control means, 22a, 22b...
ROM, 22c...Ignition timing determining means, 23...Crank angle sensor, 24...Water temperature sensor.

Claims (1)

[Claims] 1 means for detecting engine starting, means for detecting engine temperature, and means for detecting engine rotational speed;
ignition timing control means that receives the input signals from each of the means and outputs to the ignition device an ignition command signal that reduces the ignition advance value in response to a rise in engine temperature and in response to an increase in engine rotational speed when the engine is started; An ignition timing control device for starting an internal combustion engine, characterized in that: