JPH0240056A - Ignition timing control device for variable compression ratio type engine - Google Patents

Abstract

PURPOSE:To improve an engine output by a method wherein an actual compression ratio is calculated by means of a signal from a displacement amount detecting means, and by means of an intake air amount, a number of revolutions of an engine, and an actual compression ratio, an ignition timing is set to an optimum value. CONSTITUTION:An actual pressure ratio calculating means 32 A/D-converts a signal from a displacement amount detecting means 17 to detect an actual displacement amount of a compression ratio varying piston to calculate an actual compression ratio epsilonREAL. An ignition timing set means 38 retrieves an ignition timing map 39 by using a number Ne of revolutions of an engine, an intake air amount Qa, and an actual compression ratio epsilonREAL, an optimum ignition timing TIG responding to the actual compression ratio epsilonREAL is set, and an ignition coil 26 is driven through a drive circuit 41. This constitution enables prevention of lowering of an output due to the transient time delay of a compression ratio varying control system and the occurrence of malfunction of an engine.

Description

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

The present invention relates to an ignition timing control device for a variable compression ratio automobile engine that changes the volume of a combustion chamber by vertically moving a variable compression ratio piston using an actuator.

[Conventional technology]

In recent years, the volume of the combustion chamber,
In other words, variable compression ratio engines are emerging that can improve output and fuel efficiency by changing the compression ratio. Such a variable compression ratio engine has a variable compression ratio piston placed in the cylinder head that is moved up and down by an actuator such as a motor, and the volume of the combustion chamber, that is, the compression ratio, is changed by the up and down movement of the piston. The following steps are taken to set the settings and ignition timing. In other words, the amount of intake air is detected using a hot wire air flow meter, the engine speed is detected using a crank angle sensor, the knocking frequency is detected, and the displacement of the variable compression ratio piston is detected. Then, in the engine control unit, the optimum compression ratio ε is obtained as a target value by a map search etc. based on the above engine speed and intake air amount, and the actual compression ratio is adjusted to that compression ratio ε. Then, the variable compression ratio piston is operated. On the other hand, at the same time as setting the compression ratio ε as the target value, the optimal ignition timing Tlc3 is determined by map search from the engine speed and intake air amount, and ignition is performed. Further, when the knocking frequency exceeds a predetermined level and it is determined that knocking has occurred, the compression ratio ε as a target value is corrected in the direction of decreasing the compression ratio, and the ignition timing TIG is corrected and retarded, Ignition is performed at the ignition timing TIG corresponding to the corrected compression ratio ε to improve output and fuel efficiency.

[Problem to be solved by the invention]

By the way, as will be described in detail later, the compression ratio variable piston that changes the compression ratio ε is displaced by a method such as rotating a cam with an actuator consisting of a motor or the like via a drive circuit in response to the output of a control unit. , since it changes the volume of the combustion chamber, it has a mechanical time delay resulting from its drive train. Also, from the requirements of the control system, it is not desirable to rapidly change the compression ratio ε, so a certain time constant is provided. Therefore, even if the control unit changes the setting to the optimum compression ratio ε due to fluctuations in the operating state, the actual compression ratio will follow with a certain time delay. On the other hand, regarding the setting of the ignition timing T1o, there is only a time delay and it is changed at the same time as the setting of the optimum compression ratio ε as a target value, so there is a difference between the actual compression ratio and the corresponding optimum ignition timing. A transient shift occurs. For this reason, for example, as shown in Japanese Patent Application Laid-Open No. 60-230522, in order to compensate for the decrease in output due to the transient delay in the compression ratio, the ignition timing is corrected, or the ignition timing is optimized in all operating ranges. This cannot be said to be a correction that takes proper ignition timing. The present invention was made to solve the above-mentioned problems, and takes into account the time delay in filtration that occurs during variable control of the compression ratio, and calculates the optimum value according to the actual compression ratio at that time. The purpose is to obtain accurate ignition timing.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a variable compression ratio engine equipped with a variable compression ratio piston in the cylinder head, and further provides a displacement amount detection means for detecting the amount of displacement of the variable compression ratio piston, and furthermore, In the control unit that controls the timing, actual compression ratio calculation means that calculates the actual compression ratio based on the signal from the displacement amount detection means;
Compression ratio setting means for setting a target optimum compression ratio from engine speed and intake air amount; Compression ratio control means for controlling the compression ratio variable screws 1 to 1 so that the actual compression ratio becomes the optimum compression ratio. , ignition timing setting means for setting the optimum ignition timing based on the engine speed, intake air amount, and actual compression ratio.

[For production]

Based on the above configuration, the actual displacement of the variable compression ratio piston is detected by the displacement amount detection means in order to eliminate the shift in the optimal ignition timing due to the transient time delay of variable compression ratio control and to correct the decrease in engine output. , find the actual compression ratio. Then, the actual compression ratio is controlled to be the optimum compression ratio set based on the intake air amount and engine speed, and the actual compression ratio is controlled based on the calculated actual compression ratio, intake air amount, and engine speed. Set the optimum ignition timing.

【Example】

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. In FIG. 1 showing the configuration of a variable compression ratio engine, reference numeral 1 indicates a variable compression ratio engine, in which air is taken in from an air cleaner 2, the intake air amount is detected by an air flow meter 3 such as a hot wire type, and the air is passed through an intake pipe. 4, the amount of intake air is adjusted by a throttle valve 5 according to the operating state of the engine 1, and the fuel injected from an injector 6 forms a mixture, which is supplied from an intake manifold 7 into each cylinder. The exhaust gas after combustion passes through the exhaust gas 7 and the nitrogen fold 8, is purified by the catalytic converter 9, and is exhausted. This variable compression ratio engine 1 has a cylinder 10, a piston 11. Consisting of cylinder head 12, cylinder head 1
A variable compression ratio piston 13 is built into the variable compression ratio piston 13 so as to be movable up and down, and is moved up and down in cooperation with a spring 15 by rotation of a variable compression ratio cam 14, and is formed between the piston 11 and the cylinder head 12. The volume of the combustion chamber 16, that is, the compression ratio ε, is made variable, and the amount of movement of the variable compression ratio piston 13, that is, the actual compression ratio ε8. A is detected by the displacement detection sensor 17. A control unit 2 that controls this variable compression ratio engine 1
0 is a voltage signal from the air flow meter 3, a pulse signal from the crank angle sensor 21, and a throttle opening sensor 2.
2. Displacement detection sensor 17. It inputs various signals from the knock sensor 23, 02 sensor 24, etc., determines the operating state of the engine based on engine speed Ne, intake air amount Qa, etc., and performs various controls according to this operating state.
The actuator 25 is driven so that the optimum compression ratio ε is obtained, the cam 14 is rotated, and the displacement amount of the variable compression ratio piston 13 is set. Further, the optimal ignition timing TIG is determined by a map search or the like based on the operating state determined by the engine speed Ne and the intake air amount Qa, and the compression ratio ε, and the ignition coil 26 is driven accordingly. For this reason, the control unit 20, as shown in FIG.
A two-dimensional map of the optimum compression ratio ε using the intake air amount Qa and the engine speed Ne as parameters. Furthermore, as shown in Figure 3 (→~(C)), the intake air amount Q
a A three-dimensional map of the optimum ignition timing TIG using engine speed Ne and compression ratio ε as parameters is stored in advance in the ROM memory. Next, the configuration and operation of the control unit 20 will be explained in the fourth section.
This will be explained with reference to the functional configuration diagram shown in the figure and the flowchart shown in FIG. The control unit 20 is first initialized when the power is turned on (step s1oo), and the engine speed calculation means 30 calculates the engine speed Ne based on the pulse signal from the crank angle sensor (engine speed detection means) 21 ( Step S101), the intake air amount calculation means 31 A/D converts the voltage from the air flow meter (intake air amount detection means) 2 to calculate the intake air amount Qa (
Step S102). Further, the actual compression ratio calculation means 32 converts the signal from the displacement amount detection sensor (displacement amount detection means) 17 that detects the actual displacement amount of the variable compression ratio piston 13 into an A/D converter.
Then, the actual compression ratio εR is calculated (step S103). Then, the knocking determination means 33 determines whether or not knocking has occurred based on the signal from the knock sensor (knocking detection means) 23 (step S104);
When knocking is not occurring, the compression ratio setting means 34 searches the compression ratio map (Fig. 2) 35 using the calculated engine speed Ne and intake air amount Qa to read out the optimum compression ratio ε. Step 8105)
, this optimum compression ratio ε is set as a target value, and the compression ratio control means 42
, the actuator 25 consisting of a motor etc. is driven via the drive circuit 37 so that the actual compression ratio εRE A L becomes the target value, and the variable compression ratio screw I is driven via the cam 14 as described above. 13 up and down to obtain the target optimum compression ratio ε. Thereby, the output, fuel efficiency, etc. of the engine 1 can be improved. Further, the ignition timing setting means 38 searches the ignition timing map (Fig. 3) 39 and reads out the optimum ignition timing TI (l) based on the engine speed Ne, the intake air amount Qa, and the compression ratio ε, or in this case,
There is a transitional time based on mechanical elements between the target optimum compression ratio ε set by the compression ratio setting means 34 and the actual displacement (actual compression ratio εREAL) of the variable compression ratio screws I to 13. If there is a delay and a map search is performed using the optimum compression ratio ε as the target value, the ignition timing will deviate from the optimum value, so the actual compression ratio calculated by the actual compression ratio calculation means 32 is
The ignition timing map 39 is searched using AL and the optimum ignition timing TIG is set according to the actual compression ratio εREAL (step 8106), and the ignition timing correction means 40. Drive circuit 4
1 to drive the ignition coil 26. Thereby, it is possible to prevent a decrease in output due to a transient time delay of the variable compression ratio control system, and furthermore, to prevent engine malfunction from occurring. On the other hand, when the knocking determining device F9.33 determines that knocking has occurred (step S104), the ignition timing correcting means 40 adjusts the set ignition timing TIG by a predetermined amount ΔTl(
The compression ratio correction means 36 further reduces the target compression ratio ε set by the compression ratio setting means 34 by a predetermined amount Δε (step S 107).
8) The above re-operation will eliminate the knocking. In the above configuration, for example, the variable compression ratio piston 13 may become stuck due to some reason, or
Alternatively, even if the variable compression ratio control system does not operate due to a malfunction of the actuator 25, the ignition timing will be adjusted to the optimum ignition timing based on the actual compression ratio εREAL calculated from the signal of the displacement detection sensor 17. Since it is set, it will not cause any similar trouble to the ignition timing control system.

【Effect of the invention】

As described above, according to the present invention, the actual compression ratio is calculated based on the signal from the displacement detection means, and the ignition timing is optimized by searching a map based on the intake air amount, engine speed, and actual compression ratio. Since the engine speed is set at a certain value, it is possible to improve engine output and reduce fuel consumption. In addition, even if the set value of the target compression ratio changes stepwise due to sudden changes in operating conditions, operation can always be performed at the optimal ignition timing, regardless of the transient time delay of the variable compression ratio control system. No significant output reduction will occur. Furthermore, it is possible to make the ignition timing control system in a variable compression ratio engine fail-safe.

[Brief explanation of the drawing]

Figures 1 to 5 show one embodiment of the present invention.
Figure 2 shows the configuration of a variable compression ratio engine, Figure 2 shows the compression ratio map, Figure 3 shows the ignition timing map, Figure 4 shows the functional configuration of the control unit, and Figure 5 shows the operation flow. be. DESCRIPTION OF SYMBOLS 1... Variable compression ratio engine, 12... Cylinder head, 13... Compression ratio variable piston, 17... Displacement amount detection sensor (displacement amount detection means), 20... Control unit, 25... Actuator, 26...Ignition coil, 32...Actual compression ratio calculation means, 33...Knocking determination means, 34...Compression ratio setting means, 35...Optimum compression ratio map, 36...Compression Ratio correction means, 38...
Ignition timing setting means, 39...Ignition timing map, 40.
...Ignition timing correction means, 42...Compression ratio control means.

Claims (1)

[Claims] A variable compression ratio engine having a variable compression ratio piston in the cylinder head, further comprising a displacement detection means for detecting the displacement of the variable compression ratio piston, and further control for controlling the compression ratio and ignition timing. The unit includes an actual compression ratio calculation means for calculating the actual compression ratio based on the signal from the displacement amount detection means, and a compression ratio setting means for setting the target optimum compression ratio from the engine speed and the intake air amount. , compression ratio control means for controlling the variable compression ratio piston so that the actual compression ratio becomes the optimum compression ratio; and ignition timing setting means for setting the optimum ignition timing based on engine speed, intake air amount and actual compression ratio. An ignition timing control device for a variable compression ratio engine.