JPS61258953A - Control method for internal-combustion engine with variable compression ratio mechanism - Google Patents

Abstract

PURPOSE:To prevent knocking thus to improve the engine efficiency by selecting the ignition timing and fuel injection in correspondence with octane value and compression ratio then controlling an ignitor and fuel injector. CONSTITUTION:In step 100, it is decided whether high octane value control is executing or regular octane level control is executing. In steps 101 and 108, control/setting of compression ratio is executed. While in steps 102, 109, ignition timing operation and fuel injection operation are executed. Ignition timing is set in correspondence with the octane value of fuel. Consequently, knocking is prevented previously to improve the engine efficiency.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for controlling an internal combustion engine equipped with a variable compression ratio mechanism, and in particular, a method for controlling the compression ratio, ignition timing, and fuel injection amount according to the octane number of gasoline fuel. Regarding how to.

[Conventional technology]

2. Description of the Related Art Conventionally, in a gasoline engine, a method of detecting a load and a rotational speed and controlling a compression ratio according to the load and rotational speed has been disclosed in Japanese Patent Laid-Open No. 58-38343. However, with this method, if the octane number of gasoline fuel changes significantly, it is not possible to change the compression ratio to match the change, so there is a limit to how much engine efficiency can be improved.

[Problem that the invention seeks to solve]

The present invention is to select a compression ratio according to the octane number when using gasoline fuels having different octane numbers, thereby preventing the occurrence of knocking and improving engine efficiency.

[Means for solving problems]

According to the present invention, the compression ratio variable device that changes the engine compression ratio, the ignition device, the fuel injection device, the means for detecting the state of knocking, and the optimal compression ratio are set in accordance with the octane number of the fuel. multiple compression ratio maps, multiple ignition timings corresponding to each octane number and compression ratio,
It is equipped with a fuel injection amount map, determines the octane number of the fuel, selects a compression ratio from the compression ratio map, controls the compression ratio variable device to that compression ratio, and also controls the determined octane number and the selected compression ratio. ignition timing, selecting the ignition timing and fuel injection amount from the ignition timing fuel injection amount map in response to the above, and selecting the ignition device and the fuel injection device;
Provided is a method for controlling an internal combustion engine equipped with a variable compression ratio mechanism, which controls the amount of fuel to be injected.

〔Example〕

FIG. 1 is a control flowchart of the present invention, FIG. 2 is an embodiment of a variable compression ratio mechanism used in the present invention and its control system, and FIG. 3 is a map for setting the compression ratio.

In Fig. 2, a piston pin 3 with an eccentric bearing 3a is inserted between the piston 1 and the connecting rod 2 of the engine, and the compression ratio is changed depending on whether or not the movement of the eccentric bearing 3a is locked with the lock bin 5. It is something that makes you

Hydraulic pressure for driving the lock bin 5 is supplied from an oil reservoir 10 by an oil pump 11 and a control valve 12, and is introduced into the cylinder 4 via a passage 14 in the crankshaft 13 and a passage 6 in the connecting rod 2. As a result, the lock pin 5 is pushed toward the eccentric bearing 3a, and locks the eccentric bearing 3a by fitting into the hole 3b of the eccentric bearing 3a.

At this time, the distance between the crankshaft 13 and the piston pin 3 is maintained constant, that is, the high compression state a is maintained. When the control valve 12 is closed, no hydraulic pressure is supplied to the cylinder 4 (the lock pin 5 is retracted from the hole 3b of the eccentric bearing 3a, and the eccentric bearing 3a is in a state of freely rotating. At this time, the movement of the piston 1 Accordingly, the eccentric bearing 3a rotates, resulting in a low compression ratio state.The oil on the opposite side of the cylinder 4 is returned to the oil reservoir 10 via the passage 7 in the connecting rod 2 and the passage 16 in the crankshaft 13. The control valve 12 is controlled to open and close by commands from a control device (CPU) 20. In addition, signals from an intake pipe negative pressure sensor, an engine speed sensor, and a non-king sensor are input to the CPU 20. , outputs commands for controlling the ignition device and the fuel injection device.For these sensors or the ignition timing and fuel injection amount control device itself, a well-known δ can be used.

For example, the flowchart in FIG.
It represents an interrupt processing routine executed by TDC. First, in step 100, it is determined whether high-octane control (control when the fuel has a high octane rating 'a) or regular control is currently being performed. This determination is made by checking whether a specific flag Fs- is "1" or "0." This flag Fs- is set by the driver manually operating an octane number changeover switch (not shown). can also be reversed, and
It can also be automatically controlled from the CPU side.

If you are performing high-octane control, step 101
Then, the compression ratio is controlled and set using the high-octane compression ratio setting map.

The compression ratio setting map used here is predetermined, and as shown in FIG. 3, the solid line shows the compression ratio setting map for high octane and the broken line shows the compression ratio setting map for regular. When performing high-octane control, when the engine operating range, that is, the point on the map based on intake pipe negative pressure and engine speed, is above the solid line, the compression ratio is high, and when it is below the solid line, the compression ratio is high. is a low compression ratio.

In the next step 102, ignition timing calculation is performed using the ignition timing map for high-octane engine at the current compression ratio, and fuel injection amount calculation is performed using the fuel injection amount map. Although these ignition timing maps and fuel injection amount maps are not shown, they are predetermined based on the octane number and compression ratio of the fuel.

In step 103, it is determined whether or not non-king has occurred based on the output from the non-king sensor.

If knocking has not occurred, this processing routine ends, but if knocking has occurred, it is checked in step 104 whether or not it was determined that knocking has occurred during the previous execution of the processing routine, that is, if knocking has occurred continuously. Determine whether it was there or not. If knocking did not occur last time, the ignition timing is retarded by a certain angle in step 105. This is, for example, to reduce the ignition advance angle correction amount θk by a certain value. On the other hand, if knocking occurs continuously, that is, if knocking occurs again this time even though the retardation correction was performed in step 105 last time, it is assumed that the octane number of the fuel is inappropriate, and flag Fsi4 is inverted in step 106. After that, regular control will be performed.

Then, in step 107, a signal is outputted to a display (not shown) to indicate that regular control is being performed.

In step 100, if it is determined from the flag Fsw that regular control is being performed, step 100
Proceed to step 8 and check the compression ratio setting map for regular (Figure 3)
The compression ratio can be controlled and set. That is, in FIG. 3, when the point on the map based on the intake pipe negative pressure and engine speed is above the broken line, the compression ratio is high, and when it is below the broken line, the compression ratio is low.

Next, in step 109, the ignition timing is calculated using the ignition timing map for the regular engine at the current compression ratio, and the fuel injection amount is calculated using the fuel injection map.

In step 110, it is determined whether or not non-king has occurred, and if hacking has occurred, step 11
In step 11, it is determined whether or not knocking occurred during the previous execution. If non-king did not occur last time, the ignition timing is retarded by a certain angle in step 112, which reduces the ignition advance correction amount θk by a certain value, as described above.

On the other hand, if knocking occurs continuously, that is, if knocking occurs again even though the ignition advance angle was previously retarded in step 112, it is determined that trouble has occurred, and the compression ratio is fixed at a low compression ratio in step 113. With,
Processing is performed to fix the ignition timing to a value that will never cause knocking.

If it is determined in step 110 that non-king has not occurred, the process proceeds to step 114, and it is checked whether or not it was determined that non-king has occurred the last time the process of step 110 was performed. If non-king occurred last time, the process advances to step 115 and the ignition timing is advanced by a certain angle. This is achieved by increasing the ignition advance angle correction amount θk by a certain value. Next, in step 116, a count value n indicating how many times the advance angle correction has been performed is set to "
Set to 1”.

If it is determined in step 114 that knocking did not occur last time, the process proceeds to step 117, where the ignition timing is advanced by a certain angle as in step 115, and then the count value n is incremented by "11" in step 118.Next In step 119, the count value n is a constant value n0
It is determined whether or not the above is reached, and if nun, the flag Fs- is inverted in step 120, and high-octane control is thereafter performed. Then, in step 121, a display indicating that high-octane control is being performed is displayed on a display (not shown).

As mentioned above, in this embodiment, the compression ratio is controlled using a high-octane compression ratio map (Fig. 3), and the ignition timing and fuel injection amount map are used to control the compression ratio accordingly. If knocking still occurs even after retarding the ignition timing, control is automatically performed using the regular compression ratio map and the corresponding ignition timing and fuel injection amount maps. In addition, when the regular control is being performed and knocking still does not occur even after the ignition advance is advanced n0 times, the control is automatically shifted to the high-octane control. If knocking still occurs even after performing regular control and retardation correction due to the occurrence of knocking, it is assumed that some kind of failure has occurred, and the compression ratio is fixed on the low compression side and the ignition timing is retarded to prevent non-king. It is fixed at a square ignition timing. Therefore, even if the octane number of the fuel used changes, the compression ratio, ignition timing, and fuel injection amount map can be selected automatically or manually according to the octane number, and the best output and fuel consumption rate can always be obtained. be able to.

〔Effect of the invention〕

By adopting the above configuration, it is possible to achieve the object of the present invention and also to set the ignition timing according to the octane number of the fuel, so that non-king as disclosed in JP-A-59-188056 is detected. This method of controlling the compression ratio and ignition timing has the unique effect of significantly reducing the likelihood of Petzking occurring.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the control method of the present invention, and FIG.
The figure is a sectional view of one embodiment of the variable compression ratio mechanism and a schematic diagram of its control system, and FIG. 3 is a diagram showing a compression ratio setting map. DESCRIPTION OF SYMBOLS 1... Piston, 2... Connecting rod, 3... Piston pin with eccentric bearing, 5... Lock pin, 11... Oil pump, 12... Control valve, 20... CPU. Fig. 2 1... Piston 2... Connecting rod 3... Piston pin with eccentric bearing Fig. 3

Claims (1)

[Claims] A variable compression ratio device that changes the engine compression ratio, an ignition device, a fuel injection device, means for detecting knocking, and multiple compression ratio maps that each set the optimal compression ratio depending on the octane number of the fuel. and a plurality of ignition timing and fuel injection amount maps corresponding to each octane number and compression ratio, and a compression ratio variable device that determines the octane number of the fuel and selects a compression ratio from the compression ratio maps. In addition to controlling the compression ratio, the ignition timing and fuel injection amount are selected from the ignition timing fuel injection amount map in accordance with the determined octane number and the selected compression ratio, and the ignition device and fuel injection device are selected. A method for controlling an internal combustion engine equipped with a variable compression ratio mechanism, which controls the ignition timing and fuel injection amount.