JPS6134357A - Ignition timing control device for internal-combustion engine with supercharger - Google Patents

Abstract

PURPOSE:To improve the coefficient of fuel consumption and to improve the output of an engine, by providing a means which computes a correction amount of the ignition timing of an engine in response to a supercharging state signal from a supercharging state detecting means and a means which computes an ignition timing. CONSTITUTION:In a spark ignition internal combustion engine 2 with a supercharger 1, a supercharging state detecting means 3, which provides a signal responding to a supercharging state, is mounted. An ignition timing correction amount computing means 4 calculates a lead angle amount or a delay angle amount, based on a basic ignition timing, in response to a supercharging state. An ignition timing computing means 5 computes a final ignition timing after the correction amount is inputted. An ignition timing control means 7 controls the electrode of an ignition plug 6 so that ignition takes place at the final ignition timing. This prevents the occurrence of knocking and an increase in the temperature of exhaust gas, resulting in the possibility to improve the coefficient of fuel consumption and the output of an engine.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an ignition timing control device for a supercharged internal combustion engine.

In conventional internal combustion engines equipped with a supercharger, the pressure in the combustion chamber tends to rise due to supercharging, which tends to cause non-king and a rise in exhaust gas temperature. Therefore, measures are often taken to retard the ignition timing in order to prevent the occurrence of non-king and the rise in exhaust gas temperature. In this case, the amount of retardation is generally determined uniformly for each engine operating condition based on the average atmospheric conditions and, furthermore, the average performance of the components making up the control system. However, the pressure increase due to supercharging is not necessarily the same even under the same operating conditions of engine □ (ie, same rotation, same load). This is based on the influence of atmospheric conditions and variations in supercharger performance. The effect is that the tumor feeder is equipped with an air cooling system (so-called intertala).
This is especially true for those that do not have the following.

Therefore, the conventional measure of uniformly retarding the ignition timing in vehicles cannot provide optimal control. (For technology related to the present invention, please refer to □Japanese Patent Application Laid-Open No. 59-10779.

) Problems to be Solved by the Invention The present invention has been made in view of the problems of the prior art, and aims to perform optimal ignition timing control even if there are variations in atmospheric conditions or performance of the supercharger. The goal is to provide a configuration that allows

Means for Solving Problems According to the present invention, as shown in FIG. 1, in a spark ignition internal combustion engine 2 equipped with a supercharger 1, there is provided a supercharging state detection means 3 which generates a signal according to the supercharging state. , a means 4 for calculating a correction amount for the ignition timing of the engine according to the supercharging state signal from the supercharging state detection means 3, a means 5 for calculating the ignition timing by incorporating this correction amount, and a means 5 for calculating the ignition timing by incorporating this correction amount, and the calculated ignition timing. There is provided an ignition timing control device for an internal combustion engine comprising means 7 for driving an electrode of a spark plug 6 so that it is ignited at the correct timing.

The operating supercharging state detection means 3 detects the supercharging state using supercharging air from the supercharger 1. The ignition timing correction amount calculating means 4 calculates an advance amount or a retard amount with respect to the basic ignition timing depending on the detected supercharging state. The ignition timing calculation means 5 calculates the final ignition timing by incorporating this correction amount. The ignition timing control means 7 controls the electrodes of the ignition plug 6 so that ignition occurs at this final ignition timing.

Embodiment FIG. 2 G schematically shows an example of an electronically controlled fuel injection type internal combustion engine as an embodiment of the present invention. In the figure, 10 represents an engine body, 11 represents a piston, 12 represents a crankshaft, 13 represents an intake passage, 14 represents a combustion chamber of one cylinder, and 16 represents an exhaust passage.

The air flow sensor 18 detects the Φ flow rate of intake air taken in through an air cleaner (not shown).

The intake air flow rate is controlled by a throttle valve 20 that is linked to an accelerator pedal (not shown). Throttle valve 2
The intake air that has passed through 0 passes through the intake valve 22 together with the fuel injected from the fuel injection valve 21 and enters the combustion chamber 14 of each cylinder.
will be introduced in

The mixture is ignited by a spark from the electrode of the spark plug 24. The spark plug electrode is connected to an igniter 28 via a distributor 26.

The exhaust gas after being burned in the combustion chamber 14 is passed through the exhaust valve 32.
It is discharged into the atmosphere via the exhaust passage 16 and the three-way catalytic converter 3j.
: The internal combustion engine of the present invention is a supercharged type, and a mechanical supercharger 36 is provided in the intake passage 13 downstream of the throttle valve 20. Mechanical supercharger 36 is a Roots pump in this embodiment and consists of a pair of rotors 38 rotating in opposite directions. One side of the rotor 38 is provided with a clutch 40 with a boot, and a pulley portion of the clutch 40 is connected to a pulley 44 on the crankshaft 12 via a belt 42.

46 is a control circuit that performs ignition timing control, fuel injection control, and operation control of the clutch 40 of the mechanical supercharger. The control circuit 46 is configured as a microcomputer system as described below, and forms operating signals for the igniter 28, fuel injection valve 21, and clutch 40 in response to signals from each sensor.

The air flow sensor 18 is a potentiometer provided in the intake passage 13 upstream of the throttle valve 20, and generates a voltage according to the intake air flow rate.

This output voltage is sent to the control circuit 46 via *Jl.

A crank angle sensor 4 is installed in the engine distributor 26.
8 and 50 are installed. The crank angle sensors 48 and 50 are configured as Hall elements provided facing magnets 52 and 54 provided on the distribution shaft 26' of the distributor 26, respectively. The crank angle sensor 48 is configured to generate a pulse every time the crankshaft 12 rotates 30 degrees, and is used to determine the engine speed N, while the crank angle sensor 5.0 is configured to generate a pulse every time the crankshaft 12 rotates 36 degrees.
It is configured to produce this pulse every time it rotates. The pulse signals from the crank angle sensors 48 and 50 are vAl!
, t.

! , to the control circuit 46.

The exhaust path 816 is provided with a 0□ sensor 56 that generates an output in response to the oxygen concentration in the exhaust gas.

That is, two different output voltages are generated depending on whether the air-fuel ratio is on the lean side or rich side with respect to the stoichiometric air-fuel ratio. The output voltage of Ot sensor 56 is on line I1. The signal is sent to the control circuit 46 via.

A water temperature sensor 58 that detects the engine cooling water temperature and generates a voltage according to the temperature is attached to the cooling water jacket IOA of the engine body 10.

The output voltage from the water temperature sensor 58 is sent to the control circuit 46 via the line β.

Reference numeral 60 denotes a supercharging pressure sensor as a supercharging state detection sensor, which is provided in the intake passage 13 downstream of the supercharger 36. A semiconductor type pressure sensor or other type can be used as the pressure sensor 60, and an analog signal corresponding to the boost pressure P is sent to the control circuit 46 via the line 16.

The control circuit 46 is configured as a microcomputer system and includes a microphone. processing unit (MPLI)
62, Read only memory (RO1'l) 64,
It includes a random access memory (RAM) 66, an analog-to-digital converter 68, and input/output circuits 70 and 72, which are interconnected by a bus 74.

Further, 75 is a timing control circuit, which includes one free run counter, a group of conveyor registers for ignition timing control, a match judgment gate thereof, a group of conveyor registers for fuel injection control, and a match judgment gate thereof. Become.

□・ Voltage signal from air flow sensor 18, o2 sensor 56
Voltage signals from the water temperature sensor 58, pressure sensor? 6
The voltage signal from 0 is sent to an analog-to-digital (A/D) converter 68 having an analog multiplexer function, and is sequentially converted into a binary signal according to instructions from MP[] 62.

A pulse signal every 30 degrees of crank angle from the crank angle sensor 48 is sent to a well-known speed signal forming circuit provided in the input/output circuit 70, thereby forming a binary signal representing the rotational speed of the engine.

Pulse signals for every 360 degrees of crank angle from the crank angle sensor 50 are also sent to the I10 circuit 70, and are sent to the I10 circuit 70, which generates an interrupt request signal for ignition timing control, a fuel injection start signal,
Used to form other signals.

A fuel injection control circuit 77 is connected to the I10 boat 72, and the control circuit 77 includes a flip-flop circuit and a drive circuit. The Frisopflomp circuit is set by the fuel injection start signal from the timing control circuit, and is activated by the fuel injection stop signal, and the fuel injection valve 21110 port 72 is also connected to the ignition timing control circuit 77 through its quantity line l. Connected. The control circuit 77 is similarly composed of a flip-flop circuit and a drive circuit, and is reset by the energization start signal from the timing control circuit 75 and by the energization stop signal, so that the amount line It.

An ON signal is applied to the igniter 28 via the igniter 28.

Further, the I10 circuit 72 connects the clutch control circuit 7'8 to the line
, to the supercharger control clutch 40. Clutch control circuit 78 selectively engages or disengages clutch 40 in response to a clutch actuation command.

The RQM 64 stores programs and necessary data for controlling according to the present invention, and the MPU
62 performs calculations according to the program, and performs ignition timing control, fuel injection control, and supercharger control.

The program will be explained below using a flowchart.

Figure 3 is a flowchart of the main routine.
When program execution is started at 0, 102 Te is MP
Initialization of the U 62 (7) internal registers, RAM 66, A/D converter 68, and I10 port 70.72 is performed. Next, in step 104, the MPU 62 takes in retrial data representing the engine rotational speed N from the I10 port 70, and
Store in RAM 66. Further, at 106, the latest data representing the intake air flow rate Q of the engine is generated by an A/D conversion completion interrupt from the A/D converter 68, and at 108, the latest data having a value VOX corresponding to the output voltage of the Oz sensor 56 is displayed. , 110, the latest data representing the cooling water temperature THWt- is fetched, and further, at 112, a signal corresponding to the boost pressure P from the pressure sensor 60 is fetched, and the data is stored in the RAM.
66.

Next, the program flows to step 114, in which the air-fuel ratio feedbank correction coefficient CFB is calculated. The method of calculating this correction coefficient is well known, so it will not be explained in detail here, but the outline will be as follows: 0
□According to the 02 sensor output voltage (V ox) data detected by the sensor 56 and stored in the RAM 66,
When the air-fuel mixture deviates leanly from the set value, the correction coefficient CFB is decremented to reduce the amount of fuel, while when the air-fuel mixture deviates leanly, the correction coefficient is incremented to increase the amount of fuel.

In the next step 116, a fuel increase temperature correction coefficient 00 when the engine is cold is calculated. This operation itself is well known, so it will not be explained in detail, but to give an overview, RO
There is a table (map) of temperature correction coefficients according to the cooling water temperature in M64, and the cooling water temperature T detected in 110 is
A correction coefficient C8 is calculated according to the HW.

A signal every 360 degrees of crank angle from the crank angle sensor 50 serves as an interrupt request, and the MPtl 62 executes a processing routine as shown in FIG. 4 to calculate the fuel injection pulse width τ and the ignition timing θ. First, in step 120, the MPtl 62 takes in intake air flow rate data Q and rotational speed N data from the RAM 66, and when the data is R.
Retrieved from AM 66. In step 126,
The difference ΔP between the actually measured intake pipe pressure P and the optimum intake pipe pressure value PMAP during operation is calculated. In other words, the intake pipe pressure has an optimum value determined by the combination of the engine speed and load, and the data for such an optimum value is based on the rotation speed N and the intake air amount to rotation speed ratio Q/N, which is the representative load value. It is stored in the ROM 64 as a combination with. Such a table would look like this:

MP[I 62 calculates the pressure PM□ on the map with respect to N and Q/N at that time, and determines whether it is larger or smaller than the actually measured pressure P.
In the first order 128, the pressure difference Δ calculated in 126
It is determined whether P is greater than or equal to zero, and if the pressure difference ΔP at that time is positive or zero, proceed to step 130; if negative, proceed to step 1
Proceed to 32. In steps 130 and 132, fuel increase or decrease correction based on the intake pressure is performed together with the conventional calculation of a correction coefficient C6TP in case of excessive temperature. In other words, the optimum COTPM for the rotational speed N and the intake air amount-to-rotational speed ratio Q/N is expressed as a map in Rol as shown in the table below.
164.

The COTPM map MPU 62 calculates C for the value of N and Q/N at that time.
Calculate c+rPM. By multiplying this C0T□ by a correction coefficient (1+k) based on the pressure difference ΔP, a correction coefficient C6TP at the time of excessive temperature is obtained. Here, k is expressed with respect to the pressure difference ΔP as shown in the graph of FIG. 6, and this graph is stored in the RO,M 64.

As is clear from Fig. 6, the larger the pressure difference ΔP, the larger it becomes.In the case of 130 in Fig. 4, that is, when the intake pressure deviates in a direction larger than the optimum value, C07
, increases. That is, the fuel injection amount is corrected in the direction of increasing. When proceeding to step ←132, that is, when the intake pressure deviates in a direction smaller than the optimum value, C6TP decreases. In other words, the fuel injection amount will be corrected in a smaller direction.

Then, in step 134, the basic injection pulse width τ
. , OTP increase correction coefficient C0TF, feedback correction coefficient C The pulse τ is calculated.

Then, in the next step 136, the calculated injection pulse width τ plus the count value of the free run counter at that time is set in the fuel injection control conveyor register of the timing control circuit 75, and at the same time, the I10 boat 72
A fuel injection start signal is applied to the fuel injection control circuit 76, and the fuel injection valve 21 starts opening. When the value of the conveyor register matches the value of the free run counter, a fuel injection stop signal is issued from the I10 boat 72 to the fuel injection control circuit 77, and the fuel injection valve 21 is closed. Therefore, a calculated amount of fuel can be injected.

Next, the process proceeds to ignition timing control, and at step 140, it is determined whether the pressure difference ΔP mentioned above is again equal to or greater than zero.
42, if No, the program proceeds to step 144, where a correction amount θP based on the pressure amount of the ignition timing is calculated.

In other words, the actual pressure P is the set value P calculated from the map.
When it is larger than MAP, the ignition timing is retarded by θ at step 142, and conversely, when the measured pressure P is smaller than the set value PMAP calculated from the map, the ignition timing is retarded by θ. Here, the magnitude of θ is the correction coefficient k explained in FIG.
is determined by multiplying by a constant A. Next, 1
46, the well-known basic ignition timing θIIAS! is added to the correction amount θP due to the pressure P. and cold time correction amount θ. . The ignition timing θ is calculated from the addition of L. Here, the basic ignition timing is determined by the engine speed N and the load representative value Q/N, and on the other hand, the cold time correction amount θ. 0LII is the cooling water temperature T
It is determined by HW. At 148, the timing control circuit 7 calculates the ignition timing θ calculated in this way.
The energization start time is set in the energization start control conveyor register No. 5, and the energization stop time is set in the energization stop control conveyor register No. 5, respectively. When the value of the conveyor register for energization start control matches the value of the free run counter, I10 port 7
2, a signal to start energizing the igniter 28 is input to the ignition timing control circuit 77, and the igniter 28 starts being energized. When the value of the energization stop control conveyor register matches the value of the free run counter, an igniter energization stop signal is input from the 1'/O port 72 to the ignition timing control circuit 77, and the igniter 28 is de-energized. At the same time as this energization stops, discharge occurs in the electrode of the ignition plug 24 and the spark plug 24 is ignited. When this power supply is stopped, follow step 148 in Figure 4.
The igniter 28 is adjusted to match the calculated ignition timing θ.
It is well known that energization is controlled.

FIG. 5 shows a routine for operating the supercharger operating clutch 78, which is a timely (for example, 8 msec) interrupt routine. Each time the time elapses, an interrupt request is received at the interrupt port of MP[l 62, and the routine starts executing from 200. At 202, the rotation speed data stored in the N area of the RAM 66 is set to a predetermined value a (FIG. 7). Next, in step 204, it is determined whether the data of the intake air amount Q relative to the rotational speed N stored in the Q/N area of the RAM 66 is larger than b. As is clear from the supercharger operation map in Figure 7, No at 202 (N<
a) or Yes at 202 but No at 240 (Q/N<
In the operating range b), the supercharger is stopped, in which case the program proceeds to 206. MPII 62 issues a clutch 40 release signal to the clutch drive circuit from I10 port 72. Therefore, the rotation of the crankshaft 16 is not transmitted to the rotor 3B of the supercharger 36. The rotor 38 simply rotates idly due to the flow of air from the throttle valve 20 toward the combustion chamber 14, and no supercharging is performed.

In Figure 5, 202 is Yes (N>a) and 204 is Yes (
If Q/N>b), it is in the operating range of the supercharger, and the program proceeds to 208 where MP[I 62 is I10 port 72
A clutch engagement signal for the clutch 40 is output to the clutch drive circuit 78. As a result, the rotation of the engine crankshaft 12 is transmitted to the supercharger 36 via the pulley 44, belt 42, and clutch 40, the pair of rotors 38 are rotated in opposite directions, and the air is compressed and passes through the intake pipe 13 to the engine. be introduced within.

Effects of the Invention The intake pipe pressure P downstream of the supercharger 36 is under the same operating conditions (that is, the rotation speed N is the same and the load representative value Q/N is the same).
However, due to variations in atmospheric conditions and supercharger performance, they are not necessarily the same. Particularly in mechanical superchargers, a slight difference in clearance between the rotors or between the rotor and the housing results in a large change in pump efficiency, ie, boost pressure. In the present invention, the supercharging pressure P is actually measured, and depending on the measured value, the ignition timing is retarded if it deviates to a larger value, and the ignition timing is advanced if it deviates to a smaller value. Therefore, it is possible to prevent knocking and increase in exhaust temperature, maintain a high fuel consumption rate, and improve engine output.

In the embodiment, the pressure downstream of the supercharger is detected in order to detect the supercharged state, but instead of this, the supercharged air temperature can be detected downstream of the supercharger.

In this case, there is a map of supercharged air temperature with respect to rotational speed and load in the memory, and the supercharged air temperature on the map for a certain rotational speed and load value is detected, and based on the deviation from the actual supercharged air temperature. As explained in steps 130 and 132 of FIG. 4, the correction coefficient k is calculated from the graph shown in FIG.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of the present invention, Fig. 2 is a diagram showing an embodiment, Figs. 3, 4, and 5 are flowcharts showing the software of the control circuit, and Fig. 6 is a correction coefficient for pressure difference. Figure 7 is a diagram showing the operating range of the supercharger. DESCRIPTION OF SYMBOLS 10... Engine body, 26... Distributor, 28... Igniter, 46... Control circuit, 60... Pressure sensor.

Claims (1)

[Claims] In a spark-ignition internal combustion engine equipped with a supercharger, a supercharging state detection means generates a signal according to the supercharging state, and a correction amount for engine ignition timing is calculated according to the supercharging state signal from the supercharging state detection means. An ignition timing control device for an internal combustion engine, comprising means for calculating ignition timing by incorporating the correction amount, and means for driving an ignition plug electrode so that ignition occurs at the calculated ignition timing.