JPS6240546B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device that automatically controls the ignition timing of an internal combustion engine in accordance with the load of the engine.

[Conventional technology and its problems]

In general, in the ignition combustion of the intake air-fuel mixture in an internal combustion engine, there is a so-called "ignition delay period" in which explosive combustion occurs after a certain period of time from the spark ignition by the ignition plug, and the shorter the ignition delay period, the longer each cycle The combustion waveform becomes relatively gentle and stable, improving drivability.
In addition, as the absolute amount of HC and CO generated decreases, the exhaust temperature rises, and the purification performance of the exhaust gas through oxidation reaction increases, and this effect is particularly large for vehicles equipped with a catalyst in the exhaust system. .

This ignition delay period varies depending on the combustion method, turbulent flow situation in the combustion chamber, air-fuel ratio, compression ratio, etc., but the ignition timing that minimizes this ignition delay period is generally the best. It exists around 20 degrees in front of the tea ceremony.

In addition, the optimum ignition timing (MBT) that minimizes the combustion consumption rate of the engine is further advanced than the ignition timing that minimizes the ignition delay period (approximately 40 minutes before top dead center).
°), there is a discrepancy between the ignition timing aimed at improving drivability and exhaust gas purification and the ignition timing aimed at improving fuel consumption. Control cannot achieve both objectives at the same time.

The present invention aims to improve drivability and exhaust gas purification in automobile internal combustion engines in medium and low load ranges such as city driving, which are frequently used (particularly for the purpose of reducing NOx in exhaust gas). (For engines that recirculate part of the exhaust gas to the intake system, drivability is significantly reduced.) On the other hand, in high-load, high-speed ranges other than city driving, the intake air-fuel mixture becomes lean. The generation of NOx, HC, and CO is small, and the temperature of the exhaust gas is high, so the purification of the exhaust gas is good, and the fuel consumption rate is more of a problem. The purpose is to control the ignition timing to minimize the ignition delay period in the load range, and to approach the optimum ignition timing (MBT) in the high load/high rotation range.

[Means for solving problems]

To achieve this object, the present invention provides a distributor in an internal combustion engine that advances the ignition timing to the ignition timing that minimizes the ignition delay period when negative pressure below atmospheric pressure acts on the pressure chamber. A negative pressure-operated sub-advance mechanism is connected, and a pressure chamber in the sub-advance mechanism is connected to a negative pressure transmission passage from the downstream side of the throttle valve in the carburetor, while the sub-advance mechanism includes: In relation to an advance port provided in a portion slightly upstream of the closed position of the throttle valve in the carburetor, when negative pressure is generated in the advance port, the ignition timing advanced by the sub-advance mechanism is further advanced. The structure is such that the negative pressure operated main advance mechanism is connected to each other.

[Action/effect of the invention]

With this configuration, when the opening of the throttle valve in the carburetor is relatively small in the medium and low load range, the advance port is located upstream of the throttle valve and no negative pressure is generated at the advance port, so the distributor The ignition timing according to
A sub-advance mechanism related to intake negative pressure downstream of the throttle valve advances the ignition timing to minimize the ignition delay period, while increasing the opening of the throttle valve in the high load/high rotation range. Since negative pressure is generated in the advance port, the ignition timing is advanced by the main advance mechanism so as to approach the optimum ignition timing, which is located further in advance than the ignition timing advanced by the sub-advance mechanism. The angle can be controlled.

Therefore, according to the present invention, it is possible to simultaneously improve drivability and reduce HC and CO in the medium and low load range, and improve fuel consumption in the high load and high rotation range. Improving drivability in the low load range has the effect of reducing the deterioration in drivability caused by recirculating part of the exhaust gas to the intake system.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, 1 indicates an intake manifold, 2 indicates a carburetor with a throttle valve 3, and 4 indicates a distributor equipped with a breaker plate 6 with a breaker arm 5. The breaker plate 6 in the tributator 4 has a negative pressure operated sub-advance mechanism 7 which advances the ignition timing by rotating it in the direction of arrow A, and a negative pressure operated main mechanism 7. An advance angle mechanism 8 is connected via a connecting rod 9.

These advance angle mechanisms 7 and 8 are constructed by directly connecting a sub diaphragm case 10 and a main diaphragm case 11 with diaphragms 12 and 13, respectively, via a partition plate 14. The diaphragm 13 is provided with a connecting piece 17 which is pressed against the partition plate 14 by a main spring 16 in the main pressure chamber 15, and connects the connecting rod 9 from the breaker plate 6 to the sub diaphragm case 10. While adhering to the sub-diaphragm 12 inside,
The connecting piece 1 is inserted into the connecting piece 17 through the sub-pressure chamber 18, and is provided with a flange 19 at its insertion end.
7, a relatively weak sub spring 20 is provided between the sub diaphragm 12 and the connecting piece 17,
Furthermore, between the collar 19 and the inner part of the connecting piece 17,
An appropriate gap S1 is provided in the advance direction of the connecting rod 9, and an appropriate gap S2 is provided in the main pressure chamber 15 with the back surface of the main diaphragm 13.
A stopper piece 21 is provided to separate the main pressure chamber 15 from the sub-pressure. The chambers 18 are connected to the intake manifold 1 downstream of the throttle valve 3 via negative pressure transmission passages 24.

In this configuration, the throttle valve 3 of the carburetor 2
In the middle and low load range where the throttle valve 3 is throttled down, the negative pressure at the advance port 23 is close to atmospheric pressure, while the
Since the intake negative pressure further downstream is high, this negative pressure causes the sub diaphragm 12 in the sub diaphragm case 10 to move the sub spring 2 into the sub pressure chamber 18.
0, this subdiaphragm 12
The breaker plate 6 is connected to the breaker plate 6 via the connecting rod 9.
is in the direction of arrow A, and the collar 19 at the end of the connecting rod 9 is connected to the connecting piece 17.
The ignition timing is advanced by rotating it until it touches the inner part.

When the throttle valve 3 of the carburetor 2 is wide open and the load is high, the advance port 23
The negative pressure increases toward the vacuum side, and this negative pressure in the advance port 23 acts on the main pressure chamber 15, causing the main diaphragm 13 in the main diaphragm case 11 to come into contact with the stopper piece 21 on the back inside the main pressure chamber 15. The connecting piece 17 attached to the main diaphragm 13 retreats.

On the other hand, if the engine speed increases in this state, the amount of air taken into the engine will increase.
The intake negative pressure downstream of the throttle valve 3 becomes larger on the vacuum side than when the load is high and the rotation is low.
Since the sub-diaphragm 12 moves backward following the backward movement of the connecting piece 17 attached to the main diaphragm 13, the ignition timing in the distributor 4 is further advanced than the ignition timing in the medium-low load range. be.

In this case, the distance S1 between the connecting piece 17 and the collar 19
is set so that the ignition timing when the interval S1 becomes 0 is the ignition timing that minimizes the ignition delay period described above, while the main diaphragm 1
The interval S2 between No. 3 and the stopper piece 21 is set so that the ignition timing when the interval becomes 0 is the value obtained by subtracting the ignition timing that minimizes the ignition delay period from the optimum ignition timing (MBT). By doing so, the engine's ignition timing can be automatically controlled to the ignition timing that minimizes the ignition delay period in medium and low load ranges, and to the optimal ignition timing in high load and high rotation ranges.

[Brief explanation of the drawing]

Fig. 1 is a diagram of the device according to the present invention, and Fig. 2 is a diagram of the device according to the embodiment of the present invention.
FIG. 3 is an enlarged cross-sectional view of the negative pressure-operated advance mechanism shown in the figure. 1... Intake manifold, 2... Carburetor, 3... Throttle valve, 4... Distributor, 6... Breaker plate, 7... Sub advance angle mechanism, 8... Main advance angle mechanism, 23... Advance port, 22, 24...
Negative pressure transmission passage.

Claims (1)

[Claims] 1. A negative pressure-operated sub-advance mechanism is installed in the distributor of an internal combustion engine, which advances the ignition timing to the ignition timing that minimizes the ignition delay period when negative pressure below atmospheric pressure acts on the pressure chamber. connect,
A negative pressure transmission passage from the downstream side of the throttle valve in the carburetor is connected to the pressure chamber in the sub-advance mechanism, while a negative pressure transmission passage from the downstream side of the throttle valve in the carburetor is connected to the pressure chamber. In relation to the advance port provided in the part, a negative pressure operated main advance mechanism is provided which further advances the ignition timing advanced by the sub advance mechanism when negative pressure is generated in the advance port. An ignition timing control device for an internal combustion engine, characterized in that the ignition timing control device is connected to each other.