JPS6045779A - Ignition timing controller for internal-combustion engine - Google Patents

Abstract

PURPOSE:To reduce a combustion noise without sacrificing a rate of fuel consumption and power characteristics, by delaying the ignition timing of an engine in time of high engine speed. CONSTITUTION:Ignition timing by means of a centrifugal timer is set to the delay control side from optimum ignition timing so as to cause an output drop from a maximum output point to be within the range of 4% at maximum output engine speed in full load, while the said delay control value is gradually decreased at the side of lower speed than the said maximum output engine speed, making it congruous with the optimum ignition timing, and the said delay control value is gradually increased (decreasing the advance value) at the side of higher speed than the said maximum output engine speed. Thus, at the maximum output engine speed that is pretty high speed, the advance control is held down to the extent that a slight output drop is brought about, and in case of superhigh speed being more than that, further the advance control is held down to some extent, that is, there is seen a fair output drop but this must be considered as an inevitable consequence. A suchlike superhigh speed part is not remotest chance of practical use and, what is more, this disadvantage has such a reverse effect as prevention against overrotation so that it may be tolerable enough in view of practicality.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an improvement of an ignition timing control device for an internal combustion engine,
In particular, the present invention relates to an ignition timing control device for an internal combustion engine equipped with a centrifugal advance device that sets the ignition timing so as to minimize a decrease in the output of the internal combustion engine and reduce noise.

[Technical Background of the Invention] Conventionally, gasoline engines and the like have been provided with an ignition timing control device to ignite at the optimum ignition timing according to the engine rotation speed and load in order to obtain the best output performance and fuel efficiency. .

Among ignition timing control devices, a centrifugal advance device that controls ignition timing based on rotational speed utilizes the phenomenon in which a weight opens due to the centrifugal force of rotation, transmits the displacement to the timing lever using a cam mechanism, and adjusts the rotational speed. The lead angle is given accordingly. This advance angle is determined to be the ignition timing that produces the maximum output at each rotational speed under full load, that is, the optimum ignition timing.

[Problems with the background technology] However, recently, there is a tendency for gasoline engines to be designed with high compression ratios (specifically, 9.0 or higher) in order to improve fuel efficiency. When it burns, the gas temperature is high due to the high compression ratio, and the combustion speed is fast.
The noise associated with slant combustion increases as the maximum pressure inside the cylinder increases.

Setting the ignition control device to ignite at the optimal ignition timing mentioned above and increasing the compression ratio will increase output and improve fuel efficiency, but the maximum pressure in the cylinder will increase and combustion noise will increase. This is especially serious at high speed rotation, and causes practical problems.

This rJJB engine uses an aluminum alloy for its cylinder block, which has a lower elastic modulus than steel, which makes the problem louder and more serious.

Generally, when the amount of advance is large, combustion has already progressed considerably at the top dead center of the piston and the temperature has reached a high temperature, so the maximum pressure inside the cylinder increases and combustion noise increases.

The amount of advance is determined by a centrifugal advance device that is set to almost pass through the optimum ignition timing (maximum output point) at full load special rotation speed, and by a centrifugal advance device that is set to almost pass through the optimum ignition timing (maximum output point) at full load special rotation speed, and the optimum ignition timing at medium and low load ranges at medium and low speeds that are often used when driving in urban areas. The advance angle is determined by combining the vacuum advance angle device, which is set to almost pass through the The advance angle also becomes maximum, the total advance angle amount becomes maximum, and the combustion noise becomes particularly large for the above-mentioned reason.

As described above, the conventional advance angle device that is a combination of a centrifugal advance device and a vacuum advance device cannot achieve both practical fuel efficiency improvement and noise reduction.

This drawback can be solved to some extent by introducing electronic control into the advance angle control so that the amount of advance angle can be determined freely, but at present, electronically controlled advance angle devices are complicated and expensive.

[Object of the Invention] Therefore, an object of the present invention is to reduce combustion noise during high-speed rotation, which is a particular problem in practical use, without sacrificing fuel efficiency or power performance.

[Structure of the Invention] In order to achieve this object, the present invention provides an ignition timing control device for an internal combustion engine in which the ignition timing is controlled by a centrifugal advance device to reduce the output from the maximum output point at full load maximum output rotation speed. The ignition timing is set to the retard side from the optimum ignition timing so that The present invention is characterized in that it includes a centrifugal angle device that is set to gradually increase the retard amount (gradually decrease the advance amount) on the higher speed rotation side.

[Embodiments of the Invention] The present invention will be described in detail below based on the drawings. 1st
The figure is an example of the advance angle distribution of a power distributor equipped with a conventional vacuum advance angle device and a centrifugal advance angle device, with engine rotational speed and output (load) expressed as horizontal and vertical axes.

In this case, the centrifugal advance angle should be advanced so that the line passes through the maximum output point at each rotational speed when the engine is operated at full load, as shown in Figure 2, that is, the line shown by the chain line in Figure 2. The amount of angle is determined.

The solid line in Figure 1 is the full load output, and the advance angle on this line is determined by the chain line in Figure 2. However, in the case of partial load, which is the actual operating condition, the vacuum advance angle device operates. As shown in FIG. 1, the advance angle increases from this point.

The area indicated by B in Figure 1 is an area of medium to low speed and medium to low load, such as when driving in a city, and the centrifugal advance device does not operate much, but the vacuum advance device is activated to improve fuel efficiency. The advance angle is set to an appropriate value, but in the high-speed region shown in Figure 1, both the centrifugal advance device and the vacuum advance device operate to their maximum, resulting in a large advance angle, which causes the gas temperature in the cylinder to drop. Due to the increase in combustion rate, the combustion speed becomes faster, and as mentioned above, the maximum pressure increases, resulting in a significant increase in combustion noise.

As a measure to prevent this combustion noise, the case where the ignition timing is delayed is shown in FIGS. 3 and 4. The centrifugal advance angle characteristic shown in FIG. 3 is the same as the conventional one, and the fuel efficiency during 10 mode driving was measured by changing the amount of vacuum advance angle. If the ignition timing is delayed from the optimum ignition timing (MBT), noise will be reduced, but fuel efficiency will also be reduced.

Figure 4 shows the output when the use of the centrifugal advance angle of the high-speed rotation shaft is changed.

It can be seen that by reducing the advance angle amount, the noise is reduced, but the output is also reduced. FIG. 5 shows the centrifugal advance angle characteristics with respect to the engine rotational speed for each advance angle shown in FIG.

Next, embodiments of the present invention are shown in FIGS. 6 to 9. 7th
The figure shows the centrifugal advance characteristics. The amount of advance angle increases at low speeds, and as the speed increases, the amount of advance angle increases as the speed increases, and in the conventional model, the amount of advance angle is approximately 4 as shown by the broken line.
The advance angle is constant (30 degrees) above 50 ORPM. In this example, at high speed, as shown by the solid line,
For example, 28 degrees at 4500RPM (point 1), 5000P
The amount of advance angle is decreased as the speed increases, such as 26 degrees (point 2) for PM and 24 degrees (point 3) for 5500 PPM.

As a procedure for determining this centrifugal advance characteristic, in the ignition timing-output characteristic diagram at full load shown in Fig. 8, the ignition timing for the maximum output point at the designed maximum output rotation speed (5000 PPM in this example) In this example, the ignition timing is 30 degrees, and regardless of whether the advance angle increases or decreases from this point, the output will decrease.) In contrast to point 2, where the ignition timing is delayed until the ignition timing does not cause much decrease in output (30 degrees in this example). 4 degrees delayed from 2
6 degrees). If the ignition timing is delayed, the output decreases as described above, but as a comprehensive evaluation, it is determined that an output decrease of 4% or less is acceptable, but a greater output decrease would be too much of a sacrifice.

Continuously at point 2 determined as above (26 degrees for 5000 RPM), at a low speed (45000 P in this example)
PM), set point 1 (28 degrees in this example) on the advance side of set point 2, and
), set point 3 (24 degrees in this example) on the retard side of point 2.

FIG. 6 shows what the output will be when the centrifugal advance characteristic determined in this way is applied to the engine. In the figure, point 1 is at 4500 PPM with an advance angle of 2.
8 degrees, which is almost the same maximum output point as before, and point 2
At 5000RPM, the lead angle is 26 degrees, and there is a slight decrease in output due to the output at the highest output point, and point 3 is 5500PPM.
The output drops considerably at an advance angle of 24 degrees.

As described above, in the embodiment according to the present invention, from low speed to medium speed to high speed, the ignition is performed at the optimum ignition timing that provides the maximum output, as in the conventional case, and at the maximum output rotation speed, which is quite high, the output is slightly reduced. The advance angle is suppressed to such an extent that it causes a lag, and the advance angle is further suppressed at ultra-high speeds beyond that, resulting in a considerable drop in output, but this is unavoidable. Such an ultra-high-speed section has almost no chance of being used in practice, and this disadvantage can be easily tolerated in practice, as it also has effects such as over-speed prevention, which will be described later.

FIG. 9 shows an embodiment in which the centrifugal advance device according to the present invention is combined with a conventional vacuum advance device. Comparing with FIG. 1, it can be seen that at low and medium speeds, there is no difference from the conventional one, but in high speed, medium and low load area A, the advance angle changes from, for example, 50 degrees in FIG. 1 to 44 degrees in FIG.

In this way, the present invention aims to suppress the advance of the ignition timing in the ultra-high speed region and reduce combustion noise without sacrificing fuel efficiency and performance within the practical range.

Specific mechanisms for obtaining the centrifugal advance characteristic as shown in FIG. 7 according to the present invention include (a) mechanical type, (b) electric type, (
C) Three types are possible: mechanical type + electric type.

The mechanical type (a) can provide the characteristics shown in Figure 7 by using a retard governor with a spring set to operate at a rotation speed higher than the rotation speed that reaches the maximum advance position. can. Another method is to change the shape of the window hole into which the pin of the weight fits to a higher speed (in this example, 4
Of course, the shape of the window hole may be formed so that when the weight opens at a speed of 500 RPM or more, the opening angle is delayed. Regarding the electric type (b), when an ignition signal obtained from the engine is input in the power distribution cell, a certain delay time "t" is provided so that the actual secondary side ignition voltage is delayed. The time it takes for the engine's crank angle to move becomes shorter in inverse proportion to the increase in rotational speed. Therefore, by providing a constant delay time "t", the amount of retardation from the conventional advance angle increases as the rotational speed increases.

The mechanical and electrical type (C) is a system that uses both Ca> and (b) types together.

[Effects of the Invention] As explained above, according to the present invention, the following effects can be obtained.

(1) Combustion noise can be reduced by delaying the ignition timing during high speed rotation without sacrificing fuel efficiency or power performance.

In particular, combustion noise is generally large when the compression ratio is high, but the ignition timing control device according to the present invention has a significant noise reduction effect.

Further, although engines using aluminum alloy cylinder blocks also produce a lot of noise, the device of the present invention has a remarkable noise reduction effect.

(2) According to the present invention, in high-speed rotation, as the rotation speed increases, the advance angle becomes smaller, so that damage to the engine due to over-speed during practical operation can be prevented.

(3) According to the present invention, the design maximum output rotation speed can be clearly set.

[Brief explanation of the drawing]

Figure 1 is a graph showing the amount of advance with respect to rotational speed and output (load) of a conventional centrifugal/vacuum combination advance device. Figure 2 is a graph showing the change in output due to changes in ignition timing for each rotational speed at full load, and its A graph showing the maximum point, Figure 3 is a graph showing the results of measuring 10 mode fuel efficiency when the vacuum advance angle amount is changed with the same centrifugal advance angle characteristics, and Figure 4 is a graph showing the centrifugal advance angle at high speed rotation. Figure 5 is a graph showing the centrifugal advance characteristics in the case of Figure 4. Figure 6 is a graph showing the change in output when the amount is changed. Figure 6 is a graph showing the centrifugal advance angle characteristics in the case of Figure 4. A graph showing the advance angle as a parameter, Figure 7 shows the centrifugal advance angle characteristics (
Figure 8 is a graph showing the maximum output versus ignition timing using rotational speed as a parameter. Figure 9 is a graph showing the characteristics of the centrifugal advance device according to the present invention and the conventional vacuum advance device. 2 is a graph showing the distribution of advance angle with respect to rotational speed and output (load) of an internal combustion engine provided with an angle device. Fig. 6 Rotation & (RPM) - Fig. 8 7 Kokagin M (BTDC) - Fig. 7 rj: J rotation (PPM) - Fig. 9 □ (RPM) -

Claims (1)

[Scope of Claims] 1. In an ignition timing control device for an internal combustion engine, the ignition timing by a centrifugal advance device is optimized so that the output decrease from the maximum output is within 4% at full load maximum output rotation speed. The ignition timing is set to the retard side from the timing, and the retard amount is gradually decreased to match the optimum ignition timing when the rotation speed is lower than the maximum output rotation speed, and the retard amount is gradually increased when the rotation speed is higher than the maximum output rotation speed. An ignition timing control device for an internal combustion engine, comprising a centrifugal advance device configured to gradually decrease the advance amount. 2. The ignition timing control device according to claim 1, wherein the compression ratio of the internal combustion engine is 9.0 or more. 3. The ignition timing control device according to claim 1, wherein the cylinder block of the internal combustion engine is made of an aluminum alloy.