JPS58210371A - 2-point ignition engine - Google Patents

Abstract

PURPOSE:To enhance the operability upon cold engine conditions and the durability of an engine, by providing two plugs in an engine combustion chamber and by carrying out 2-point ignition only upon low load condition and upon cold engine condition. CONSTITUTION:An engine coolant temperature switch 19 is disposed between a start detecting switch 18 and a relay coil 4a. Since a coolant temperature switch 19 is turned off upon cold engine conditions, electrical current does not run through a relay coil even when a high load detecting device 17 closes the switch, and therefore, the change-over to one-point ignition is prevented since relay contacts 14b is still turned on. Since the coolant temperature switch 19 is turned on after the engine is warmed up, the normal change-over mode in which the one-point ignition is carried out upon high load operation and the 2-point ignition is carried out upon low load operation, is established. Thereby, the operability of the engine upon cold engine condition is enhanced and the durability of the engine is also enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a two-point ignition engine that includes two spark plugs in the engine combustion chamber and provides high rate exhaust gas recirculation.

A two-point ignition engine eliminates NOx emitted from the engine.
In order to reduce nitrogen oxides (nitrogen oxides), two ignition systems are provided at relatively distant positions in the combustion chamber, while a portion of the exhaust gas is recirculated into the intake air at a high rate (e.g., approximately 30 cm). However, due to rapid combustion based on two-point ignition, the generation of NOx can be significantly suppressed without changing the operating state of the engine. However, when the engine is under high load, the combustion conditions are not very good, and the rate of increase in combustion pressure is high, which may lead to durability problems and increased noise. The system uses the throttle valve opening as necessary to switch to single-point ignition (stops operation of one of the spark plugs) during high loads, improving engine durability and reducing noise. Furthermore, a two-point ignition engine was proposed which also aimed at improving the starting characteristics by always igniting at two points when starting the engine (Utility Model Publication No. 56-50146).
It is shown in FIG.

This is an example of a 4-cylinder ennon; in the figure, 1 is the engine body, 2 is the intake manifold P13 is the exhaust manifold, 4 is the exhaust recirculation passage, 5 is the exhaust recirculation control valve, 6 is the engine combustion chamber, and 7a and 7b are the exhaust manifolds. Two spark plugs are arranged in the engine combustion chamber 6 at positions relatively apart from each other, and usually ignite at almost the same time. 8 is a distributor that connects the interrupter section 9 and the two power distribution sections I.
Qa, 10t), and ignition coils 11a, l
One ignition coil lla that supplies high voltage current to each ignition plug 7a, 7b via lb and the power distribution section 10a are connected to one of the ignition plugs 7
The ignition coil llb and the power distribution unit 10b receive the other ignition plug 7b series, and the primary coil of ignition coil llb and the ignition coil 1b are connected to the ignition plug 7b series so as to stop the ignition action of the ignition plug 7b series when the engine is under high load. switch 1
A contact 14b of a normally closed relay 14 is inserted between the relay coil 14a and the battery 13, a negative pressure detection switch 15 that responds to engine suction negative pressure to detect high load, and a throttle valve opening. Throttle valve opening detection switch 16 that responds to
When either switch 15 or 16 is turned on, the relay coil 14 & is energized, and its contact 1
4b opens and the ignition plug 7b series is shut off.

Note that the negative pressure detection switch 15 indicates that the suction negative pressure is, for example, -
The throttle valve opening detection switch 16 is turned on when the pressure is close to the atmospheric pressure of 80 sHg, and when the throttle valve opening is, for example, 40 degrees or more.

Next, to ensure two-point ignition when starting the engine, a start detection switch 18 is inserted between the high output detection means 17 and the relay coil 14a. A gear switch is used to detect the neutral position of the gear, or by detecting the disengaged state of the clutch, the neutral point potential of the alternator, the operation of the starter circuit for the starter motor, the pressure of engine oil, etc. When starting, be sure to close the relay coil 14a.
The current is cut off and the contact 14b is turned on, so that the two series of spark plugs 7a and 7b operate simultaneously.

According to this configuration, in normal operating conditions, both the negative pressure detection switch 15 and the throttle valve opening switch 16 are in the off state, so the relay coil 14a of the relay 14 is not energized and the contact 14b is closed. both ignition coils
Both a and llb are kept energized, and therefore, as the interrupter section 9 opens and closes, the ignition coils lla and 1
1. The high EE current from b is simultaneously supplied to the spark plugs 7a, 7b via the power distribution units 10a, 10b.

Next, when the engine is under high load and either the suction negative pressure decreases below a predetermined value or the throttle valve opening increases above a predetermined value, the negative pressure detection switch When the detection switch 16 is turned on, the relay coil 14a
A current flows to turn off the normally closed note point 14b. As a result, the passage to the second ignition coil llb is cut off, so the supply of high-pressure current to the ignition plug 7b series is stopped, and only the other ignition plug 7a series continues the ignition action. The previous two-point ignition will be switched to one-point ignition.

On the other hand, when starting the engine, the suction negative pressure is close to atmospheric pressure, so if it continues to vibrate, the negative pressure detection switch 15 will turn on, energizing the relay coil 14a, and contact 14b.
When the engine opens, the operation of the spark plug 7b series stops, resulting in one-point ignition and the loss of good starting performance based on two-point ignition.However, when starting, the start detection switch 18 must be opened. Since the normally closed relay 14 is maintained in the on state, two-point ignition can be reliably performed.

As described above, when the engine is under high load, this can be accurately detected and ignited at one point, preventing increased noise and deterioration of durability, while at the same time ensuring good starting characteristics by igniting at two points when starting. I was getting it.

By the way, in such a two-spark plug 7a system, the fuel atomization characteristics are still poor in a cold engine state immediately after starting, and the throttle valve opening increases even though the combustion time is slow. When the high load detection means 17 closes the switch,
There was a problem in that the relay contact 14b was opened and the ignition was switched to one point ignition, resulting in poor drivability.

The present invention has been made by focusing on these problems.
A means for detecting a cold state of the engine is provided, and when the engine is cold, two-point ignition is maintained at high load or even when a high load state is detected, and combustion time is substantially accelerated to perform proper combustion. The purpose is to improve drivability when the engine is cold.

Hereinafter, the present invention will be described based on the drawings, in which substantially the same parts as in FIG. 1 are denoted by the same reference numerals.

In FIG. 2, a water temperature switch 19 for detecting engine coolant temperature, for example, is inserted between the start detection switch 18 and the relay coil 14a as a means for detecting a cold state of the engine. Note that the water temperature switch 19 is kept in an off state when the engine is cold.

According to this configuration, since the water temperature switch 19 is off when the engine is in a cold state, the high load detection means 17 is turned off when the engine is under high load.
Even if the switch is closed, no current flows through the relay coil 14&, and the relay contact 14b remains on, preventing the switch from switching to one-point ignition and maintaining two-point ignition.

On the other hand, after warm-up, the water temperature switch 19 is turned on, so the operation is the same as in FIG. 1 without means for detecting the cold state of the engine.

This is another embodiment in which only a water temperature switch 19 is provided, and the other parts are the same as those in FIGS. 1 and 2, and the same parts are given the same reference numerals.

In this case as well, when the engine is cold, the water temperature switch 19
is off, so the two-point ignition is always maintained, and the water temperature switch 19 is turned on after warm-up.When the load is low, the two-point ignition improves engine operability, and when the load is high, the high load detection means 17 The switch is closed to switch to single-point ignition, which improves the durability of the engine and reduces noise.However, since the start switch 18 is closed, the engine cannot be restarted after warming up. During a so-called hot start, when the load is high, the switch of the high load detection means 17 closes and the mode switches to one-point ignition, but since the engine cooling water temperature is high, the startability is good and there is no problem. .

In this case, a starting switch as a means for detecting the engine starting state is not required, so the structure is simplified.

As described above, in the present invention, a means for detecting the cold state of the engine is provided, and the high load detection signal is canceled when the engine is cold, so that two-point ignition is maintained regardless of the load. The effect is that the drivability in a cold state can be improved.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view showing a conventional example, FIG. 2 is a schematic plan view showing one side of the present invention, and FIG. 3 is a schematic plan view showing another example. 14...N closed relay, 14a...relay coil, 14b...contact, 17...high load detection means, 18
...Start detection switch, 19...Water temperature switch. ％Applicant Nissan Motor Co., Ltd.－J °－ Agent Patent Attorney Masaru Goto 31

Claims (1)

[Claims] Two ignition plugs are provided at positions relatively apart from each other in the engine combustion chamber, two ignition systems operate the respective ignition plugs, an engine high load detection means, and a signal from the detection means is used when the load is high. The two-point ignition engine is equipped with a means for stopping the operation of one of the ignition systems, and a means for detecting a cold state of the engine is provided, so that two-point ignition is performed when the engine is cold, regardless of the high load detection signal. This is a two-point ignition engine.・