JPS6296727A - Power output control method of engine - Google Patents

Abstract

PURPOSE:To enable the high power of an engine to be exhibited all the time by controlling both the ignition timing and the exhaust system, item such as the exhaust timing and the like, which influences the dynamic effect of an exhaust gas flow so that the maximum power output is obtained in response to the mean temperature of exhaust gas temperatures in an exhaust pipe and also to the engine speed. CONSTITUTION:On an exhaust pipe 7 is provided a sensor 11 for detecting the exhaust gas temperature. In addition, on a crankshaft 3 is provided another sensor 12 for detecting the engine speed. And then, detection signals from each of the sensors 11, 12 are input to a control unit 16 so as to operate a drive unit 17. Hereupon, in the drive unit 17, an ignition system unit 17a controls through an ignition coil 18 the ignition timing of a sparking plug 4; while an exhaust system unit 17b drives with the aid of an actuator 14 a rotary valve 8, and, at the same time, drives by means of an actuator 15 a closing valve 10. Hereby, the exhaust timing and the pressure wave form are controlled respectively so that the power output resulting from the dynamic effect of exhaust gas flow can be improved to the utmost limit.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to an engine output control method.

[Prior art]

Generally, the ignition timing of an engine is controlled to advance as the engine rotates at higher speeds in order to produce maximum output according to the engine speed.

Furthermore, it is known that the output characteristics of an engine are largely influenced by dynamic effects of gas flow in the exhaust pipe, generally referred to as inertia effects and pulsation effects. In other words, there is a phenomenon in which the pulsating waves of exhaust gas discharged from the exhaust port of the engine to the exhaust pipe are reflected from the end of the exhaust pipe and reach the exhaust port again, and whether the positive pressure or negative pressure of this pulsating reflected wave is It is known that the output is greatly influenced by whether the exhaust hole is reached during the opening period.

For example, in the case of a two-stroke engine, if the control is performed so that a negative pressure reflected wave reaches the exhaust hole during the opening period of the scavenging hole, this negative pressure wave will be transmitted to the combustion chamber and the scavenging passage.

It reaches the intake hole through the crankcase and sucks in a larger amount of fresh air, and immediately after that, a reflected wave of positive pressure reaches the exhaust hole, preventing the fresh air pushed into the combustion chamber from flowing out. . Therefore, these improve filling efficiency and
It is possible to increase the output.

Conventionally, such pulsating reflected waves of the gas flow in the exhaust pipe have been controlled by controlling exhaust system specifications such as exhaust timing in accordance with the engine rotational speed. However, the propagation speed of reflected waves changes depending on the temperature, and has a characteristic that it is faster when the temperature is high and slower as the temperature is lower. For this reason, simply controlling the exhaust timing according to the engine speed as described above will not work, for example, when the exhaust pipe is cooled by rain when driving in the rain, or when driving in the bitter cold of winter. When the tube is strongly cooled, the propagation speed of the reflected wave becomes slower than in a steady state, so the improvement in output due to the above-mentioned dynamic effect is reduced.

[Purpose of the invention]

The purpose of the present invention is to solve the above-mentioned problems, to prevent the output characteristics from being affected by the dynamic effect of the exhaust gas flow due to differences in temperature around the exhaust pipe, and to provide an engine that can always produce high output. The object of the present invention is to provide an output control method.

[Structure of the Invention] The present invention, which achieves the above object, adjusts the ignition timing and the exhaust timing according to the average temperature of the gas inside the exhaust pipe detected by a plurality of sensors arranged in the longitudinal direction of the exhaust pipe and the engine rotation speed. It is characterized by controlling the exhaust system specifications that govern the dynamic effects of the exhaust gas flow, such as the following, to maximize output.

〔Example〕

The present invention will be explained below with reference to embodiments shown in the drawings.

FIG. 1 shows a motorcycle engine to which the present invention is applied, and 1 is a two-cycle engine. In this two-stroke engine 1, 2 is a piston, 3 is a crankshaft,
4 is a spark plug, 5 is an intake hole, 6 is an exhaust hole, and 7 is an exhaust pipe connected to the exhaust hole 6.

A rotary valve 8 is provided above the exhaust hole 6 to open and close the upper opening of the exhaust hole 6. As described later, this rotary valve 8 is controlled via an actuator 14 according to the engine speed and the gas temperature in the exhaust pipe, and by changing the opening degree of the upper opening of the exhaust hole 6, the piston 2 is moved into the exhaust hole. The exhaust timing when closing 6 is adjusted.

The exhaust pipe 7 has a straight pipe part 7f of the same diameter at the front part, an enlarged diameter part 7r with an enlarged diameter is connected to the rear part thereof, and a muffler part 7 at the rearmost part.
m is connected. A resonance chamber 9 is provided at the front end of the straight pipe section 7f so as to branch out, and a butterfly-shaped on-off valve 10 is installed at the entrance of the resonance chamber 9.
is provided. As will be described later, this on-off valve 10 is controlled via an actuator 15 in accordance with the engine speed and the exhaust pipe gas temperature, and its opening degree is adjusted.

Further, the exhaust pipe 7 is provided with a total of four sensors 11 such as thermocouples or thermistors for detecting exhaust gas temperature, two in the straight pipe part 7f and two in the enlarged diameter part 7r. On the other hand, a sensor 12 consisting of a pickup such as an electromagnetic coil is provided opposite to the crankshaft 3 to detect the engine speed.

The output signals of these sensors 11, 11 and the detection signal of sensor 12 are input to a control section 16 consisting of a microcomputer, and the control section 16 is controlled based on these signals.
is adapted to drive the drive unit 17. At this time, the exhaust gas temperatures detected by the plurality of sensors 11, .

Of the drive units 17, the ignition system unit 17a controls the ignition timing of the spark plug 4 via the ignition coil 18, and the exhaust system unit 17b of the drive unit 17 drives the rotary valve 8 via the actuator 14. The exhaust timing is controlled so as to maximize the output improvement due to the dynamic effect of the exhaust gas flow, which will be described later. In addition, exhaust system unit 1
7c drives the on-off valve 10 via the actuator 15, changes the pressure waveform of the exhaust gas depending on its opening degree, and similarly controls the output improvement due to the dynamic effect of the exhaust gas flow to be maximized. As shown in FIG. 2, other exhaust system specifications may be added to the exhaust system unit of the drive unit 17 to control other exhaust system specifications, if necessary.

In the above-described control, the engine speed (r.

Optimum ignition timing to maximize output according to p, m, )
BTDC--upper row point front angle) is controlled to advance as the engine rotation speed increases, as shown in FIG. In addition, the optimal exhaust timing (0^TDC...) that maximizes the output according to the engine speed (r, p, m,)
・The angle after top dead center) and the optimum opening/closing valve rotation angle θ (''・- opening degree based on the closed state - see Figure 1) are determined by
It is carried out as shown in FIG. The latter control of optimal exhaust timing and optimal opening/closing valve rotation angle is intended to increase output due to the dynamic effect of exhaust gas flow, and to control the pulsating reflected waves of negative pressure when the scavenging hole is open. Extend it to the exhaust hole 6,
The air flows through the combustion chamber, the scavenging passage, and the crankcase to the intake hole 5 to suck in a larger amount of fresh air, and then when the exhaust hole 6 immediately after it opens, a reflected wave of positive pressure is applied. to prevent fresh air forced into the combustion chamber from escaping. This improves fresh air charging efficiency and increases output. Further, the optimum opening/closing valve rotation angle is such that the pressure waveform of the exhaust gas is changed by controlling the rotation angle of the opening/closing valve 10, so that the effect of the negative pressure and positive pressure reflected waves described above can be obtained.

In the present invention, the optimum ignition timing, optimum exhaust timing, and optimum opening/closing valve rotation angle are controlled by the control unit 16 not only based on the engine speed, but also corrected according to the exhaust pipe gas temperature detected by the sensor 11. will be held. That is, the propagation speed of the pulsating wave changes depending on the temperature, and as shown in FIG. 3, the change in exhaust gas pressure at the outlet P of the exhaust hole 6 becomes like a curve when the exhaust pipe 7 is slightly cooled. However, when it is strongly cooled, it becomes a delayed state as shown by curve B. For this reason, the output improvement characteristics due to the dynamic effect of the exhaust gas flow also change depending on the exhaust gas temperature, so by correcting this based on the exhaust pipe gas temperature, the output improvement due to the dynamic effect can be maintained and "high output" can be maintained at all times. In this way, the optimal ignition timing, optimal exhaust timing, and optimal opening/closing valve rotation angle corrected based on the gas temperature in the exhaust pipe are as shown in Figures 7, 8, and 9. It will be done.

In other words, in the case of ignition timing, if the ignition timing is delayed, the exhaust gas temperature will rise, so when the exhaust pipe is cooled and the exhaust gas temperature is low, such as when driving in the rain, the ignition timing should be adjusted. The exhaust gas temperature is corrected by delaying it toward top dead center and increasing the exhaust gas temperature. In addition, in the case of exhaust timing, if the exhaust timing is advanced, the exhaust gas temperature will increase, so when the exhaust gas temperature is low, such as when driving in the rain, the exhaust timing should be advanced toward top dead center. This is a correction that increases the exhaust gas temperature.

Moreover, in the present invention, a plurality of sensors 11. Since the average value of . . . -, 11 is used, control with extremely high precision can be performed. That is, the exhaust gas temperature in the exhaust pipe 7 is high in the straight pipe section 7f near the exhaust hole 6 of the engine 1, as shown in the temperature curve E shown in FIG. 10, but gradually decreases in the enlarged diameter section 7r. ,
Depending on the measurement location, the above correction control may lack accuracy, but by using the average value of the detected temperatures at multiple locations along the longitudinal direction of the exhaust pipe 7 as the control factor as described above, errors caused by external factors can be eliminated. It can be reduced.

Further, it is desirable to arrange as many sensors 11 as possible along the longitudinal direction of the exhaust pipe 7 for detecting the exhaust gas temperature, but when the number is only two, it is preferable to arrange the sensors 11 in the straight pipe section 7f. It is preferable not to arrange it, but to arrange it only in the enlarged diameter part 7r.

This is clear from the temperature curve E in Figure 10,
Regarding the temperature distribution inside the exhaust pipe 7, in the straight pipe part 7f with a small cross-sectional area, the flow velocity of the exhaust gas is high and the temperature change in the length direction is large, so the error depending on the measurement position becomes large. This is because the flow rate of the exhaust gas is slow in the enlarged diameter portion 7r, and the temperature change in the longitudinal direction is also small, so errors due to measurement positions are small.

〔Effect of the invention〕

As described above, the output control method of the present invention adjusts the ignition timing, exhaust timing, etc. according to the average temperature of the gas inside the exhaust pipe detected by a plurality of sensors arranged along the length of the exhaust pipe and the engine rotation speed. The exhaust system specifications that govern the dynamic effects of the exhaust gas flow are controlled to maximize output, so when the exhaust gas temperature changes due to temperature changes around the exhaust pipe, the output increases due to the dynamic effects of the exhaust gas flow. It can always produce high output without loss of power.

Furthermore, since the average value of the temperatures detected by a plurality of sensors installed in the longitudinal direction of the exhaust pipe is used as the exhaust pipe internal gas temperature, there is no error due to measurement locations, and accurate control can be performed.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a motorcycle engine to which the control method of the present invention is applied, FIG. 2 is a conceptual diagram of the same control method, FIG. 3 is a diagram of fluctuations in exhaust gas pressure at the exhaust port outlet, and FIG. The figure shows the relationship between engine speed and optimal ignition timing, Figure 5 shows the relationship between engine speed and optimal exhaust timing, Figure 6 shows the relationship between engine speed and optimal opening/closing valve rotation angle, and Figure 7 shows the relationship between exhaust timing. Figure 8 is a diagram showing the relationship between gas temperature in the exhaust pipe and optimal ignition timing, Figure 9 is a diagram showing the relationship between gas temperature in the exhaust pipe and optimal opening/closing valve rotation angle, and Figure 10 is a diagram showing the relationship between gas temperature in the exhaust pipe and optimal opening/closing valve rotation angle. FIG. 3 is a relationship diagram between pipe gas temperature and exhaust pipe position. 1--engine, 3--crankshaft, 4-single spark plug, 5-intake hole, 6-exhaust hole, 7-exhaust pipe,
7f-straight pipe section, 7r-expanded diameter section, 8-rotary valve, 9
...resonance chamber, 10-opening/closing valve, 11--(exhaust pipe gas temperature) sensor, 12-(engine speed) sensor, 14.15--actuator,
16...-control unit, 17...-drive unit, 18...-ignition system unit.

Claims (2)

[Claims] (1) Dynamic effects of exhaust gas flow, such as ignition timing and exhaust timing, are controlled according to the average temperature of the gas inside the exhaust pipe detected by multiple sensors arranged along the length of the exhaust pipe and the engine speed. An engine output control method characterized by controlling exhaust system specifications to maximize output. (2) The engine output control method according to claim 1, wherein two sensors are provided in the enlarged diameter portion of the exhaust pipe, and the two sensors detect the average temperature of the gas inside the exhaust pipe.