JPS58155278A - Ignition timing control device in engine - Google Patents

Abstract

PURPOSE:To make it possible to carry out ignition always with optimum timing irrespective of secular change, by compensating the timing of ignition in accordance with a deviation between a measured value of compressed pressure upon enging low speed and a reference value. CONSTITUTION:Upon operation of an engine 1 an idle discriminating circuit 2 receives an engine rotational speed N and a throttle valve opening degree TVO and therefore, discriminates whether the engine 1 is in the idle condition or not. A signal (a) is applied from the circuit 2 to a cylinder internal pressure measuring circuit 3 when the idle condition is determined, so that an internal pressure in a cylinder at the top dead center of the compression cycle, or a compression pressure Pi is calculated in consideration with a crank angle theta and a cylinder internal pressure Pn. This pressure Pi is compensated in accordance with a deviation DELTAN between an engine rotational speed N and a reference speed No in a compensating circuit 4 so that a pressure Pic is obtained. Then, this pressure Pic is compared with a cylinder internal pressure reference value Pio from a circuit 5 in a differential pressure calculating circuit 6, and with the use of the thus obtained deviation DELTAPi, ignition timing TIG which is obtained in an arithmetic circuit 8 is compensated in a compensating circuit 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition timing control device for an engine.

Generally, an engine ignition timing control device is used to appropriately control ignition timing in response to changes in engine operating conditions. For conventional ignition timing control devices, the ratio of the maximum cylinder pressure during motoring, which does not cause the mixture to explode, and the maximum combustion pressure when the engine completely explodes and causes the mixture to explode, is determined at the maximum torque. Minimum ignition advance angle
um 5parkAdvance for Be5t
Focusing on the fact that Torque (hereinafter referred to as MBT) is closely related, the cylinder pressure and maximum combustion pressure at a predetermined advance angle before crank angle compression top dead center are detected respectively, and the cylinder pressure and maximum combustion pressure are detected according to various engine operating conditions. There is a system that corrects the ignition timing calculated by Showa 52
(Refer to Publication No.-151432).

However, with the ignition timing control device described in the above-mentioned publication, MuT cannot be set in operating conditions where the idling state (9MBT), which does not require maximum torque, and the advance angle at which knocking occurs are very close to each other or reversed. It is not possible to correct the timing control, resulting in problems such as occurrence of knocking, reduction in fuel efficiency, and deterioration of exhaust gas conditions.

Incidentally, there is the following relationship between the ignition timing of the engine and the cylinder pressure in relation to the occurrence of knocking in the engine, the fuel efficiency, and the quality of the exhaust gas condition. In other words, the ignition timing of the engine is designed to be between 3,000 and 4,000.
The settings are based on the engine condition at the time of completion of lapping, which is a period of about 100 km of driving.For example, during engine lapping, the piston ring does not fit into the cylinder, pressure leaks occur, and the cylinder pressure drops to lapping. If the pressure is lower than the pressure at the time of completion [see Figure 2], the combustion speed of the air-fuel mixture will slow down, unburned gas will increase, and fuel efficiency may decrease. Therefore, the ignition timing should be set lower than the set value. It is desirable to advance the angle. In addition, if carbon adheres to the piston after lapping is completed, the pressure inside the cylinder will increase, which may increase the combustion speed of the air-fuel mixture and cause knocking. , it is desirable to retard the ignition timing from the set value,
Furthermore, if the engine has been used for a long time and the piston rings have worn out, the pressure inside the cylinder will drop, so in this case it is desirable to advance the ignition timing. Particularly when the engine is running at low engine speeds, the fluctuations in cylinder pressure due to aging can cause knocking, reduced fuel efficiency, and deterioration of exhaust gas conditions. Correction is strongly required, and correction of ignition timing control is also required when there is a difference in cylinder pressure due to engine manufacturing errors, that is, when there are individual differences between engines.

As mentioned above, when trying to correct the engine's ignition timing control according to changes in cylinder pressure, it is necessary to measure the cylinder pressure at compression top dead center, that is, the compression pressure. In this case, when the engine is running at high speed, the time interval between the compression pressure Pi and the maximum combustion pressure P is extremely short, as shown in Figure 1, and the compression pressure P
While it is very difficult to measure i, when the engine is running at low speed, the time interval between the compression pressure Pi and the maximum combustion pressure Pa is relatively large, and the compression pressure Pi
As mentioned above, this invention makes it possible to measure compression pressure when the engine is running at low speeds, in situations where correction of ignition timing control is required according to changes in cylinder pressure. The ignition timing was calculated based on the operating condition of the engine, and the cylinder pressure at compression top dead center at low engine speeds was measured, and this measured value and a preset reference value were calculated. By correcting the ignition timing according to the deviation between the An object of the present invention is to provide an engine ignition timing control device that improves the engine ignition timing control device.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 shows an engine ignition timing control device according to an embodiment of the present invention. In the figure, 1 is an engine, 2 is an idle determination circuit that determines whether or not the engine l is in an idling state from the engine speed N and throttle valve opening TVO, and 3 is an idle time signal a from the idle determination circuit 2. While receiving the output θ of the crank angle sensor and the output h of the cylinder pressure sensor, the compression top dead center (T, D) is reached.

4 is the output P of the cylinder pressure measurement circuit 3;
i and the output N of the rotation sensor, the compression pressure Pi is determined by the difference Δ between the engine rotation speed N at the time of pressure measurement and the reference rotation speed NO.
Cylinder internal pressure correction circuit corrects according to N, 5 is engine 1
Reference rotational speed NO and reference throttle valve opening degree T V O at the time of completion of lapping.

This is a comparison reference value generation circuit that generates the compression pressure at Pio as the reference value Pio.

Further, 6 is a differential pressure calculation circuit that calculates the deviation △Pi between the compression pressure Pic corrected in the cylinder internal pressure correction circuit 4 and the reference compression pressure Pio, and 7 is a differential pressure calculation circuit that stores the output of the differential pressure calculation circuit 6 and stores it as it is. A differential pressure storage circuit outputs the deviation △Pi stored from before V while receiving the non-idling signal from the idle judgment circuit 2. 8 is the engine rotation speed when the lapping of the engine 1 is completed. The ignition timing TIG, which is determined according to An ignition timing calculation circuit that generates an ignition timing TIG according to the pressure P; 9 is an ignition timing T calculated by the ignition timing calculation circuit 8;
An ignition timing correction circuit that corrects IG according to the deviation 611.1722 rotation speed N from the differential pressure storage circuit 7 and the intake negative pressure P; It is an ignition device that performs

The ignition timing control device 11 of this embodiment is constituted by a portion surrounded by a dashed line in the figure.

Next, the operation will be explained.

When the engine 1 starts operating, the rotation sensor (not shown) detects the engine rotation speed N, the throttle opening sensor (not shown) detects the throttle valve opening T■0, and the idle judgment circuit 2 detects the engine rotation speed N. The output N and TVO are received, and the engine speed N and the throttle valve opening TVO are compared with respective set values for idle determination to determine whether or not the engine is in an idling state.When the engine is idling, The idle determination circuit 2 adds the idle signal a to the cylinder pressure measurement circuit 3, and
calculates the cylinder pressure at the compression top dead center, that is, the compression pressure Pi, from the output θ of the crank angle sensor (not shown) and the output Pn of the cylinder pressure sensor (not shown), and calculates the cylinder pressure Pi at the compression top dead center. Add to. This correction circuit 4 receives the output N of the rotation sensor and converts the compression pressure Pi into a pressure P according to the deviation ΔN between the engine rotation speed N and the reference rotation speed NO.
ic = Pixft]. Here f 1 (
□) is a function for correcting the calculated compression pressure Pi to a value equivalent to the reference rotation speed No when the engine rotation speed N at the time of calculation of the compression pressure Pi deviates from the reference rotation speed No by ΔN.

The differential pressure calculation circuit 6 compares the corrected compression pressure Pic with the cylinder internal pressure reference value Pio from the comparison reference value generation circuit 5, calculates the compression pressure deviation ΔPi, and stores it in the differential pressure storage circuit 7. In addition, the circuit 7 stores the deviation ΔPi.

On the other hand, the ignition timing calculation circuit 8 receives the output N of the rotation sensor and the output P of the negative pressure sensor (not shown), and starts the ignition from an address determined by the engine speed N and the intake negative pressure P of the initial setting ignition timing map. The timing TIG is read out and the ignition timing P is added to it, and the circuit 9 reads the ignition timing TIG output from the ignition timing calculation circuit 8.
(=Ignition timing T I G f1 correction term f according to compression pressure deviation △Pi, engine speed N and intake negative pressure P
Add 2(ΔPi, N, P). Here, [2(△Pi,
N, P) are functions for correcting the ignition timing based on the compression pressure deviation ΔPi and the operating state of the engine (rotational speed N and intake negative pressure P). Therefore, the ignition timing TIG is advanced by a value corresponding to the compression pressure deviation △Pi and the engine operating condition during lapping of an engine with a low compression pressure Pi, and when carbon adheres to the piston, the compression pressure Pi crystallizes. When this occurs, the ignition timing is retarded by a value corresponding to the compression pressure deviation ΔPi and the operating state of the engine, and the ignition device 10 performs ignition at this corrected ignition timing TIG.

Additionally, as the engine speed increases and the engine becomes non-idling, the time interval between the time the engine reaches compression top dead center and the time when maximum combustion pressure is obtained becomes extremely sluggish, making it difficult to measure compression pressure. Therefore, there is a possibility that the ignition timing cannot be corrected according to the compression pressure deviation. However, in this case, in this device, the idle determination circuit 2 applies the non-idling signal S to the differential pressure storage circuit 7, and the differential pressure storage circuit 7 applies the compression pressure deviation ΔPi stored during idling.
is added to the ignition timing correction circuit 9, the ignition timing TIG is corrected even during non-idling according to the compression pressure deviation ΔPi and the operating state of the engine, as in the case of idling.

The device of this embodiment as described above measures the in-cylinder pressure at compression top dead center when the engine is idling, calculates the deviation between it and a preset reference value, and compares this deviation with the engine operating state. Since the ignition timing is corrected according to engine differences and changes in cylinder pressure due to aging, ignition is always performed at the optimal timing, reducing the occurrence of knocking and reducing fuel consumption and exhaust gas. The situation will be improved.

FIG. 3 shows a case in which the ignition timing control device 11 is constructed from a hardware circuit, and FIG. 4 shows a 70-chart of the processing procedure when the ignition timing control device 11 is constructed using a microcomputer. In the figure, 12 is a determination step that reads the engine speed N and throttle valve opening [TVO] and compares them with the set value for idling determination to determine whether or not it is in an idling state. 14 is a step of reading the current engine rotation speed N when calculating the compression pressure Pi, and 15 is a step according to the difference ΔN between the engine rotation speed N and the reference rotation speed NO. to reduce the compression pressure Pi to the pressure P
This is a step of correcting ic = Pi X [1 (ΔN).

In addition, 16 calculates the deviation △Pi between the corrected compression pressure Pic and the reference compression pressure Pio at the reference rotational speed NO and reference throttle valve opening 3 T V Uo at the time of completion of engine lapping, and stores it in the memory area. The storing step 17 is a step of reading the engine speed N and intake negative pressure P, which are parameters of the engine operating state, and calculating the ignition timing T I G in the current engine operating state using the initial setting ignition timing map. be. Here, the initial setting ignition timing map is a map of the ignition timing required by the engine upon completion of engine lapping in accordance with the engine speed and intake negative pressure. 18 is a determination step for determining the presence or absence of the compression pressure deviation ΔPi; 19 is the ignition timing TIGt calculated from the initial setting ignition timing map; timing TIGt corresponding to the compression pressure deviation Pi; the engine speed N and the intake negative pressure P; Step 20 is a step of adding a correction term lx (ΔPi, N, P), and step 20 is a step of providing ignition timing TIG to the ignition device.

Next, the operation will be explained.

When the engine is idling, the microcomputer performs steps 12, 13, 14, 15, 16.1.
7 and 18, in step 13 the compression pressure Pi is calculated, in step 14 the engine rotation speed N at the time of calculation of the compression pressure Pi is read, and in step 15 the compression pressure Pi is calculated as a pressure Pic according to the engine rotation tiN. = P
i X ft (ΔN) IC correction, step 16
Compression pressure Pic and reference value Pi after correction.

In step 17, the initial setting ignition timing map is used to calculate the ignition timing TIG in the current engine operating state, and in step 18, the presence or absence of the compression pressure eccentric portion P i is determined. judge. If there is a compression pressure deviation ΔPi, proceed from step 18 to step 19 and add a correction term f2 (ΔPi, N, P) for the ignition timing TIG according to the compression pressure deviation ΔPi and the engine operating state to the calculated ignition timing TIG. The power. Then, in step 8, give it to the ignition device number at step 20. If the compression pressure deviation ΔPi is zero, the process proceeds from step 18 to step 20, and the calculated ignition timing TIG is directly applied to the ignition device 10.

In addition, when the engine is not idle, it is difficult to control the compression pressure Pi, so the microcomputer performs step 12.17.1B, 19.20 or step 12.17.
, 18 and 20, and in step 19, the deviation ΔPi stored in the memory area during the idling is read out, and the ignition timing 1° IG read out from the initial setting map is corrected.

Note that the present invention is not limited to the above embodiments (but is not limited to these).
For example, the compression pressure may be detected not only when the engine is idling but also when the engine is running at low speed. Further, the processing flow of the microcomputer may be different from that shown in FIG. 4 as long as it achieves the same function.

As described above, according to the engine ignition timing control device according to the present invention, the ignition timing is calculated according to the operating state of the engine, the compression pressure at low engine speed is measured, and the measured value and the preset Since the ignition timing is corrected according to the deviation from the reference value, it is possible to always ignite at the optimal timing even if there are individual engine differences or changes in cylinder pressure due to aging. This has the effect of reducing the occurrence of knocking and improving fuel efficiency and exhaust gas conditions.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing changes in cylinder pressure with respect to engine crank angle, FIG. 2 is a diagram showing temporal changes in cylinder pressure, and FIG. 3 is an engine ignition timing control device according to an embodiment of the present invention. FIG. 4 shows the ignition timing f611 of an engine according to another embodiment of the present invention. It is a flowchart figure of the processing procedure of the microcomputer in gl device ilt. l...Engine, 3...Cylinder pressure measurement circuit, 6...
- Differential pressure calculation circuit, 7... Differential pressure storage circuit, 8... Ignition timing calculation circuit, 9... Ignition timing correction circuit, 10...
Ignition device. % Applicant Toyo Kogyo Co., Ltd. Agent Patent Attorney Ken Hayase − Figure 1 Crank angle □ Figure 2 Before time −

Claims (1)

[Claims] (1) An ignition timing calculation circuit that calculates ignition timing according to engine operating conditions, a cylinder pressure measurement circuit that measures the cylinder pressure at the top dead center of the compression stroke at low engine speeds, and measurement of the cylinder pressure measurement circuit. a differential pressure calculation circuit that calculates the difference between the cylinder pressure reference value and a preset cylinder internal pressure reference value; a differential pressure storage circuit that stores the output of the differential pressure calculation circuit; and a differential pressure storage circuit that stores the output of the differential pressure storage circuit; An ignition timing control device for an engine, comprising an ignition timing correction circuit that corrects the output of the arithmetic circuit and applies it to the ignition device.