JPH06307320A - Ignition device of spark ignition type engine - Google Patents

Abstract

PURPOSE:To reduce total NOx discharge quantity and make it hard to cause engine stall up by setting ignition timing while an engine is loaded in the total loading area later than that in a partial loading area and overloading area at the same engine speed. CONSTITUTION:An intake air negative pressure signal corresponding to intake negative pressure is transmitted to an ignition controlling device 3 from a negative pressure sensor 20 which is a part of an engine load detecting means 1, and an engine load is detected at the ignition controlling device 3. Engine speed is detected by the ignition indicating signal transmitted from an ignition indication detecting sensor 17 which is an engine speed detecting means 2 in the ignition controlling device 3. Based on the detection of an engine load and engine speed, the ignition controlling device 3 judges that the engine load is in a total load area 21, ignition timing in the total load area is set later than that in a partial load area and overload area 22 at the same engine speed. This constitution can reduce NOx discharge concentration in the longest running time total load area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition device for a spark ignition type engine, and more particularly to an ignition device capable of reducing the total amount of NO _x emission and causing less engine stall.

[0002]

2. Description of the Related Art As a prior art of an ignition device for a spark ignition type engine, there is one having the following basic structure as in the present invention. That is, the engine load detection means and the engine rotation speed detection means are associated with the ignition control device, the ignition control device is configured to detect the engine load and the engine rotation speed, and the ignition control device is associated with the ignition plug.
There is a configuration in which the ignition control means controls the ignition timing of the spark plug based on the detection of the engine load and the engine rotation speed.

In this prior art, as indicated by the solid line in FIG. 2, the ignition control device detects that the engine load is in the full load region, and the ignition control device sets the ignition timing in the full load region to the same engine. It is set so as to be slower than the partial load region in the rotation speed and to be the same as the ignition timing in the overload region. That is, at the same engine rotation speed, the ignition timing in the full load range and the ignition timing in the overload range are matched.

The ignition timing is set by improving the output performance and NO.
It is set in consideration of the conflicting performance compromises of reducing _X emission concentration. By the way, if the ignition timing is set earlier with emphasis on output performance, it is advantageous for securing output, reducing fuel consumption and preventing engine stall, but since the maximum combustion temperature becomes high,
NO _X emission concentration there is a disadvantage that high. On the other hand, focuses the NO _X emission concentration reduction, is set to late ignition timing throughout, NO _X emission concentration is an advantage to be low, but the combustion state becomes worse than the previous case, reduced output performance There is a disadvantage to

In the above prior art, as shown by the solid line in FIG. 2, the output performance is emphasized and the ignition timing is set earlier as a whole.

[0006]

The above-mentioned prior art has the following problems because the ignition timing in the full load range and the ignition timing in the overload range are matched with each other. Since the ignition timing in the full load region and the ignition timing in the overload region are matched and output performance is emphasized, the ignition timing is set earlier in all of these operating regions. . Therefore, in these operating regions, the maximum combustion temperature is high and the NO _X emission concentration is high. In this case, the NO _X emission concentration becomes high in the full load region where the operating time is the longest, so that the NO _X emission amount becomes large.

In order to solve the problem, it is conceivable to sacrifice the output performance to some extent, place an emphasis on the reduction of the NO _x emission concentration, and set the ignition timing later as a whole as shown by the chain line in FIG. . However, in this case, the ignition timings of both the full load region and the overload region are set to be delayed, and the output becomes low. In this case, engine stall is likely to occur because the output becomes low in the overload region where high output is required.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ignition device for a spark ignition type engine, which can reduce the total amount of NO _x emission and can prevent engine stall.

[0009]

In the present invention, as illustrated in FIG. 1 (A), the engine load detection means 1 and the engine rotation speed detection means 2 are made to cooperate with an ignition control device 3, and an ignition control device 3 is provided. Is configured to detect the engine load and the engine rotation speed, the ignition control device 3 is associated with the ignition plug 4, and the ignition control unit 3 causes the ignition plug 4 to ignite based on the detection of the engine load and the engine rotation speed. An ignition device for a spark ignition type engine configured to control the timing is characterized by the following.

That is, on the basis of detecting that the engine load is in the full load range, the ignition control device 3
As illustrated in FIG. 1B, the ignition timing in the full load range is set to be later than the ignition timing in the partial load range and the overload range at the same engine speed.

[0011]

Since the ignition timing in the full load range can be set late and the ignition timing in the overload range can be set early, the following advantages can be obtained. By setting the ignition timing late in the full load range,
Since most NO _X emission concentration in long full load region of the operating time can be lowered, NO _X emissions is reduced. Even if the ignition timing is set earlier in the overload region, the operating time in the overload region is short, so that the total NO _X emission amount is not significantly affected.

By setting the ignition timing earlier in the overload region, the output in the overload region can be secured, so engine stall is unlikely to occur.

[0013]

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram for explaining an ignition device of a spark ignition type engine according to an embodiment of the present invention, and FIG. 1 (A) is a schematic diagram of the engine,
FIG. 1B is a graph showing the advance characteristic of the ignition timing.

This engine is a spark ignition type three-cylinder gas engine, and its construction is as follows. As shown in FIG. 1 (A), a piston 6 is fitted in a cylinder 5, and the piston 6 is interlockingly connected to a crankshaft 8 via a connecting rod 7. A combustion chamber 9 is formed in the cylinder 5, and an intake passage 10 and an exhaust passage 11 are connected to the combustion chamber 9. A venturi 12 is provided in the intake passage 10, and a throttle valve 13 is arranged downstream of the venturi 12. A gas cylinder 14 is connected to the venturi 12. The throttle valve 13 is linked to a speed control lever (not shown) via a governor device (not shown).

The structure of this engine ignition device is as follows. An ignition plug 4 is provided in the combustion chamber 9, and the ignition plug 4 is linked to the ignition control device 3 via an ignition coil 15. The ignition control device 3 is a microcomputer. A disk-shaped ignition instruction rotor 16 is externally fitted and fixed to the crankshaft 8, an ignition instruction detection sensor 17 is exposed on the outer periphery thereof, and this is linked to the ignition control device 3. The ignition instruction rotor 16 has a single starting point setting projection 18 having a short circumference and an ignition instruction projection 19 having a long circumference on its outer circumference.
It has and. The three ignition indicating projections 19 are arranged according to the crankpin angle. Since this engine has three cylinders, it is arranged every 120 °.
Reference numeral 23 in the figure is a battery.

In this ignition device, when the starting point setting protrusion 18 and each ignition instruction protrusion 19 pass near the ignition instruction detection sensor 17, a detection signal having a length proportional to the circumference is ignited from the ignition instruction detection sensor 17. It is transmitted to the control device 3. In the ignition control device 3, the detection signal indicates that the starting point setting protrusion 18
It is discriminated whether it is the starting point setting signal based on the above or the ignition instruction signal based on the ignition instruction projection 19 by the difference in the length. Further, the three types of ignition instruction signals based on the three types of ignition instruction protrusions 19 are specified by the reception order starting from the reception of the start point setting signal. Then, the corresponding three cylinders are ignited in order in the order of receiving the ignition instruction signal.

In order to adjust the ignition timing according to the engine operating condition, this ignition device has the following structure. A negative pressure sensor 20 for detecting an intake negative pressure is arranged downstream of the throttle valve 13 in the intake passage 10 and is linked to the ignition control device 3. The negative pressure sensor 20 is used as the engine load detecting means 1. That is, in this engine, due to the action of the governor mechanism, the opening degree of the throttle valve 13 increases as the engine load increases and the intake negative pressure on the downstream side of the throttle valve 13 decreases (vacuum side) under a constant rotation speed. Therefore, the engine load can be detected by detecting the intake negative pressure.

Further, the ignition instruction detection sensor 17 is also used as the engine rotation speed detection means 2. From the negative pressure sensor 20 which is the engine load detecting means 1, an intake negative pressure signal corresponding to the intake negative pressure is transmitted to the ignition control device 3, and the ignition control device 3 detects the engine load. Further, the ignition instruction detection sensor 17 which is the engine rotation speed detection means 2
The engine speed is detected by the ignition control device 3 based on the ignition instruction signal transmitted from the vehicle.

The ignition control device 3 detects the engine speed and the engine speed based on the detection of the engine speed.
The ignition timing is adjusted as shown in FIG. That is, on the basis of detecting that the engine load is in the full load range, the ignition control device 3 determines the ignition timing in the full load range as the ignition timing in the partial load range and the overload range at the same engine speed. Set to be slower than.

Thus, it is possible to set the ignition timing in the full load region to be late and, at the same time, to set the ignition timing in the overload region to be early. Therefore, there are the following advantages.
That is, by setting the ignition timing to be late in the full load region, the NO _x emission concentration in the full load region where the operating time is the longest can be lowered, so that the total NO _x emission amount is reduced.
Even if the ignition timing is set earlier in the overload region, the operating time in the overload region is short, so that the total NO _X emission amount is not significantly affected. Further, by setting the ignition timing earlier in the overload region, the output in the overload region can be secured, so engine stall is unlikely to occur.

The details of the advance characteristic of the ignition timing by this ignition control device will be described with reference to FIG. In this embodiment, the position where the load is 100% is set as the total load point 21, and the load 90
The range of% -120% will be described as the full load region, the range of less than 90% of the load as the partial load region, and the range of more than 120% as the overload region. The setting of the load area is merely an example. In this embodiment, the ignition timing is kept constant in the full load region where the load is 90% to 120%.

Further, in the partial load region where the load is less than 90%, the ignition timing is delayed as the load increases, but the retardation rate of change of the ignition timing with respect to the increase in the load is almost equal to the load 7.
They are made different with the 0% region as the boundary. That is, the retardation change rate in the case of the heavy partial load of 70% to 90% of the load is set to be larger than the retardation change rate in the case of the light partial load of less than 70% of the load.

As a result, the ignition timing can be set earlier in the entire light load region where the load is less than 70%. Therefore, there are the following advantages. That is, by setting the ignition timing earlier in the light partial load region where the load is less than 70%,
Increase the output here. Even if the ignition timing is set earlier when the load is less than 70% (particularly when the load is less than 50%), NO _X is essentially unlikely to occur in this range.
O _X greatly affects the total emissions can increase the output without.

As shown in FIG. 1B, the load 12
In the overload region of 0% or more, the ignition timing is advanced as the load increases, but the advance rate change rate of the ignition timing with respect to the load increase is the retard angle change in the heavy partial load region of 70% to 90% load. The rate is about the same as the rate, and is larger than the retardation change rate in the light partial load region where the load is less than 70%. For this reason,
The ignition timing near the maximum load point 22 can be set earlier.
Therefore, there are the following advantages. That is, the maximum load point 22
By setting the ignition timing in the vicinity early, it is possible to increase the output here and enhance the engine stall suppression function. Even if the ignition timing at the maximum load point 22 is set earlier, the operating time in the vicinity is originally short, so the engine stall suppressing function can be enhanced without significantly affecting the NO _x total emission concentration.

In FIG. 1B, the ignition timing of the spark plug 4 is indicated by the crank angle shown on the vertical axis. For example, the ignition timing of -10 ° means that the ignition is performed when the crank angle is 10 ° before the top dead center. still,
The ignition timing obtained from this graph is just an appropriate value when the engine speed is a predetermined value,
These appropriate values change according to changes in the engine speed. These appropriate values at a specific engine rotation speed are selected in advance based on experiments, etc., stored in the ignition control device 3 as map data, and corresponding data is extracted based on the detection of the engine rotation speed.
The ignition timing is controlled based on this data.

The contents of the embodiment of the present invention are as described above, but the present invention is not limited to the above embodiment. For example, the advance characteristic of the ignition timing is not limited to that shown in FIG. 1 (B), but may be arbitrarily changed within the range not departing from the spirit of the present invention. Further, the engine to be applied is not limited to the gas engine and may be another spark ignition type engine such as a gasoline engine. Further, the engine load detecting means and the engine speed detecting means may be other ones.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an ignition device of a spark ignition type engine according to an embodiment of the present invention, FIG. 1 (A) is a schematic diagram of the engine, and FIG. 1 (B) is a graph showing ignition timing characteristics.

FIG. 2 is a view corresponding to FIG. 1 (B) of a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine load detection means, 2 ... Engine rotation speed detection means, 3 ... Ignition control device, 4 ... Spark plug.

Claims (1)

[Claims] 1. An engine load detection means (1) and an engine rotation speed detection means (2) are linked to an ignition control device (3),
The ignition control device (3) is configured to detect the engine load and the engine rotation speed, and the ignition control device (3) is associated with the ignition plug (4) to detect the engine load and the engine rotation speed. The control means (3) has a spark plug (4)
In the ignition device of the spark ignition type engine configured to control the ignition timing of, the ignition control device (3) detects that the engine load is in the full load range. An ignition system for a spark ignition type engine, wherein ignition timing is set to be later than ignition timings in a partial load region and an overload region at the same engine speed.