JP3038833B2 - Ignition timing control device - Google Patents

Description

The present invention relates to an ignition timing control device for an outboard motor or the like,
More particularly, the present invention relates to an ignition timing control device suitable for an outboard motor that exhausts using negative pressure generated in water by rotation of a propeller.

[Conventional technology]

9 (a) and 9 (b) show a schematic configuration of the outboard motor, where (a) shows the entire configuration and (b) shows a detailed structure of a part of the exhaust system. It is a thing.

9 (a) and 9 (b), the engine holder 3
The exhaust from the cylinder 1b in the cylinder block 1 provided above is exhausted from the exhaust port 1a, through the exhaust cover 2, through the exhaust tube 4, into the exhaust chamber 6, and exhausted through the air exhaust hole 5 into the air. At the same time, the water is exhausted into the water from an underwater exhaust hole 8 provided on the shaft of the propeller 7.

FIG. 10 schematically shows the electrical configuration of a conventional outboard motor, in which the same components as those in FIG. 9 are indicated by the same reference numerals.

In Figure 10, the ignition timing control unit 9 for controlling the ignition timing of the engine, the ignition coil 10 ₁ for generating a high voltage for ignition, 10 ₂ are shown, the pulser coil 12 _1, 12 ₂ Generates a pulse that detects the rotational position of the crankshaft. A magneto (not shown) generates a power supply voltage for each unit. Gear account coil 14,
A pulse is generated by detecting the teeth of the ring gear. A carburetor (not shown) atomizes the fuel and supplies it to the cylinder 1b. The throttle opening sensor 16 generates a signal that detects the opening of the throttle.

In FIG. 10, the ignition timing control unit 9 includes a pulsar coil # 1 mounted at a specified angle of the crankshaft.
Based on the rotation angle detection pulse supplied from (12 ₁ ) and the pulsar coil # 2 (12 ₂ ) via the waveform shaping circuit 31, the gear pulse counting circuit 32 causes the gear coil 14 to rotate, for example, at every rotation angle of 1 °. The counting of the detected pulses is started, and when a predetermined number of counts is reached, a signal for detecting the crank angle is generated.
1 _1), SCR # turn on 2 (21 _2). As a result, the energy previously stored in the capacitor 24 is transferred to the ignition coil # 1 (10 ₁ ) and the ignition coil # 2 (10 ₂ ) by the voltage generated by the capacitor charge coil 23.
By discharging through, by generating a high voltage to the secondary side performs ignition in the cylinder at the ignition plug 24 _1, 24 _2.

The count number in this case is determined according to the throttle opening signal detected by the throttle opening sensor 16.
It is controlled by the count number control circuit 34. The shift position detection switch 35 detects the reverse position of the operation lever (not shown), and changes the control amount of the count number control circuit 34 at the time of reverse.

In the example of FIG. 10, the throttle opening sensor 16 is of a variable resistance type, and from a constant voltage given from the power supply circuit 35,
Outputs a voltage that changes according to the throttle opening.

FIG. 11 shows an example of the throttle characteristic, and shows that an output voltage (V) that changes linearly in accordance with the throttle opening (゜) is generated.

FIG. 12 shows an example of the ignition timing characteristics. The count number control circuit 34 includes a throttle opening sensor.
The ignition timing (゜) is controlled in accordance with the throttle opening (゜) by determining the count number according to the 16 output voltages.

[Problems to be solved by the invention]

Unlike an automobile or a motorcycle, the exhaust system of the outboard motor is an underwater exhaust system that uses negative pressure generated by the rotation of a propeller. Therefore, the exhaust pressure depends on the shift position (forward, neutral, reverse) and the water level in the exhaust pipe. Has a characteristic that greatly changes.

In the case of an outboard motor mainly composed of two-stroke engines, if the exhaust pressure changes significantly, the amount of air-fuel mixture and the mixing ratio that enter the cylinder during combustion will change, and the engine output will increase even at the same throttle opening and the same ignition timing. As it changes, the change in exhaust pressure is important.

FIG. 13 shows the relationship between the water level, the shift position, the exhaust pressure, and the number of revolutions.

(1) Influence of water level In the case of an outboard motor, its height relative to the water surface varies depending on the size and shape of the hull to be mounted. Then, for example, the water level A shown in FIG.
As in the case of the water level B, a difference occurs in the water level.

When the engine speed is low and thus the amount of exhaust is small, and the exhaust pressure does not reach the exhaust pressure for pushing the water level in the exhaust chamber 6 to the position of the underwater exhaust hole 8, the exhaust is discharged from the air exhaust hole 5. It has become.

At this time, when the water level is high as indicated by B and the lower end of the exhaust tube 4 is underwater, the exhaust pressure increases. Further, the pressure in the exhaust chamber 6 also increases.

(2) Influence of shift position Even with the shift position, a large difference occurs in the exhaust pressure as the engine speed increases.

For example, in the case of forward, the amount of exhaust increases with an increase in the engine speed, the exhaust pressure increases, and the water level in the exhaust chamber decreases as C → D → E as shown in FIG. . On the other hand, due to the rotation of the propeller 7 and the forward movement of the hull, the underwater exhaust hole 8 at the rear end of the propeller becomes a negative pressure, and the exhaust in the exhaust chamber is sucked out. The pressure drops.

In the case of reverse, the propeller rotates in the reverse direction and the hull moves backward, so that the underwater exhaust hole 8 at the rear end of the propeller does not become a negative pressure, and the exhaust pressure increases as the engine speed increases and the amount of exhaust increases. Ascending, the air begins to be exhausted from the underwater exhaust hole 8 and then saturates as shown in FIG.

In the case of neutral, as in the case of reverse, as the engine speed increases and the amount of exhaust increases,
The exhaust pressure rises.

As described above, in the outboard motor, the exhaust pressure changes depending on how the outboard motor is mounted, the number of passengers, the difference in water level depending on the load weight, and the shift position. When the exhaust pressure changes in this manner, the engine speed (engine output) changes even with the same throttle opening and the same ignition timing, as indicated by X in FIG.

In an outboard motor, particularly at the time of reverse, a large load is applied due to the shape of the hull, so that a decrease in engine output becomes a serious problem.

That is, even with the same throttle opening, when the engine speed decreases, the negative pressure decreases, and the amount of fuel to be atomized decreases. As the number of revolutions decreases, the required fuel per unit time also decreases. However, if the amount of fuel atomized further decreases, the mixture ratio decreases and the number of revolutions further decreases.

For this reason, there is no room for transient phenomena such as sudden closing of the throttle, and in some cases, a problem such as engine stall occurs.

[Object of the invention]

The present invention is to solve such problems of the prior art, and in order to solve the problem of an increase in exhaust pressure and a decrease in engine output associated therewith in an outboard motor or the like,
It is an object of the present invention to provide an ignition timing control device that detects an exhaust pressure and corrects (advances) the ignition timing according to the exhaust pressure, thereby preventing a decrease in engine output.

[Means for solving the problem]

According to the first aspect of the present invention, the exhaust tube extends downward in the exhaust chamber, and is exhausted from the air exhaust hole provided in the exhaust chamber or the underwater exhaust hole provided in the propeller shaft through the exhaust tube. In addition, when the water level in the exhaust chamber is high, the lower end of the exhaust tube is used for an internal combustion engine for an outboard motor in which the lower end is submerged. In the advance control device for controlling the ignition timing, a pressure detection unit for detecting the exhaust pressure in the exhaust chamber is provided, and the ignition timing is advanced as the exhaust pressure detected by the pressure detection unit is higher. , Is adopted.

According to a second aspect of the present invention, the ignition timing control device is provided with a shift position detection switch, and the advance angle control device controls the ignition timing of the internal combustion engine based on the output of the shift position detection switch. The other configuration is the same as that of the first aspect.

According to a third aspect of the present invention, the advance angle control device adopts a configuration in which the ignition timing is controlled during acceleration, and the other configurations are the same as those of the first or second aspect.

(Operation)

In an electric advance angle control device, an exhaust pressure of an internal combustion engine is detected to generate an output, and the output of the exhaust pressure is added to the output of a throttle opening sensor to control the ignition timing of the internal combustion engine. As a result, the ignition timing can be corrected (advanced) in accordance with the exhaust pressure, and therefore, a decrease in the output of the internal combustion engine due to an increase in the exhaust pressure can be prevented.

〔Example〕

FIG. 1 shows the overall configuration of one embodiment of the present invention. Here, the same components as those in the conventional example in FIG. 9 are indicated by the same reference numerals.

In FIG. 1, reference numeral 9 denotes an ignition timing control unit for controlling the ignition timing of an engine, and reference numeral 10 denotes an ignition coil for performing ignition in a cylinder. Reference numeral 11 denotes a pressure sensor for detecting the pressure in the exhaust chamber 6, and reference numeral 11a denotes a detection tube connecting the pressure sensor 11 and the exhaust chamber 6. Further, reference numeral 12 is a pulsar coil for detecting a specific crank angle, reference numeral 13 is a magneto for generating a power supply voltage for each part, reference numeral 14 is a gear coil for detecting teeth of a ring gear, and reference numeral 15 is a carburetor for atomizing fuel. Reference numeral 16 denotes a throttle opening sensor for detecting the opening of the throttle.

In this embodiment, a pressure detecting unit 36 (FIG. 2) is provided in an internal combustion engine having an ignition timing control unit 9 for controlling the ignition timing of the internal combustion engine in accordance with the output indicating the throttle opening from the throttle opening sensor 16. Then, an output is generated by detecting the exhaust pressure of the internal combustion engine, and the ignition timing control unit 9 adds the output of the pressure detection unit 36 (FIG. 2) to the output of the throttle opening sensor 16 to generate the ignition timing of the internal combustion engine. Is performed.

FIG. 2 shows a configuration of an ignition timing control system provided in FIG. In FIG. 2, reference numeral 36 denotes a pressure detector. The pressure detector 36 generates a voltage indicating the pressure in the exhaust chamber 6 based on the detection signal of the pressure sensor 11 shown in FIG.

FIG. 3 shows an electrical configuration of the pressure detecting section.

In FIG. 3, a reference voltage is generated from a power supply through a resistor 41 to a Zener diode 42, and a constant current circuit including an operational amplifier 43 and a transistor 44 supplies a constant current to a detection unit 45. The detection unit 45 forms the main body of the pressure sensor 11 and generates an unbalanced voltage in the bridge circuit according to the pressure in the exhaust chamber 6. The differential voltage proportional to the pressure is taken out of the detection unit 45 by the differential amplifier circuit by the operational amplifiers 46 and 47, and the operational amplifier
It is amplified by the amplifier circuit consisting of 48 to obtain an output voltage V _0.

FIG. 4 exemplifies the output characteristics of the pressure detector, and generates an output voltage (V) that changes linearly according to the pressure (mmHg) (or kPa) of the exhaust chamber 6.

On the other hand, as described above, the exhaust pressure of the exhaust chamber 6 changes as shown in FIG. 13 according to the throttle opening.
Therefore, the output voltage of the pressure detector 36 corresponding to the throttle opening changes with different characteristics depending on the water level and the shift position.

FIG. 5 shows the relationship between the throttle opening and the output voltage of the pressure detector.

In the ignition timing control system shown in FIG. 2, the count number corresponding to the output voltage of the throttle opening sensor 16 is added to the exhaust pressure by adding the output voltage of the pressure detection unit 36 to the count number control circuit 34. By making the change in accordance with the above, it is possible to obtain the advance angle characteristic that compensates for the decrease in the engine output due to the increase in the exhaust pressure described above.

The count number control circuit 34 generates an output voltage by adding the output characteristic shown in FIG. 5 to the basic throttle opening sensor output shown in FIG.

FIG. 6 shows the output voltage of the count number control circuit, where C is the output voltage of the throttle opening sensor, to which the output voltage of the pressure detector shown in FIG. 5 is added. As a result, an output voltage as shown in FIG. 6 is obtained.

In the gear pulse count circuit 32, a count number control circuit
To determine the number of pulses that vary in accordance with the output voltage of 34, by controlling the opening and closing of SCR21 _1, 21 ₂ via the signal distribution circuit 33 to determine the ignition timing at the spark plug 24 _1, 24 _2.

FIG. 7 shows the characteristics of the ignition timing (゜) corresponding to the throttle circuit (゜), where C indicates the output voltage of the throttle opening sensor and determines the basic ignition timing characteristics.

As shown in FIG. 7, even with the same throttle opening,
It is shown that when the exhaust pressure is different based on the difference between the water level and the shift position, the ignition timing is different, and when the exhaust pressure is high, the ignition angle is advanced compared to when the exhaust pressure is low. Therefore, even when the exhaust pressure is high, a decrease in the number of revolutions can be prevented.

In this case, the setting of the ignition timing is rough when the angle is advanced too much in the low speed range, causing vibration, and when the angle is excessively retarded, the engine stalls. Therefore, generally, the seventh
In the basic ignition timing characteristic indicated by C in the figure, in order to reduce roughness, in consideration of acceleration and the like, in the range where the throttle opening is small, the retard is retarded as much as possible without causing engine stalling, and the throttle opening becomes large. Accordingly, the angle is gradually advanced to obtain high output.

Further, it is not easy to determine a set value that does not stall even at the time of reverse with a large load and a high exhaust pressure while giving importance to a forward which is frequently used. However,
According to the present embodiment, it is possible to set the ignition timing in consideration of the difference between the forward and reverse shift positions and the water level, and it is possible to set an optimum setting under each condition.

Further, at the time of rapid acceleration, the exhaust pressure increases due to an instantaneous increase in the exhaust amount due to an increase in the number of revolutions with respect to the volume of the exhaust pipe. On the other hand, at the time of rapid deceleration, on the contrary, the exhaust amount instantaneously decreases with respect to the exhaust pipe volume, and the exhaust pressure slightly decreases. Thereby, a slight acceleration effect by the advance angle can be obtained at the time of rapid acceleration, and a slight deceleration effect can be obtained at the time of sudden deceleration.

FIG. 8 shows a change in the exhaust pressure and a change in the number of revolutions during such rapid acceleration and rapid deceleration. In addition, the shift position detection switch 35 shown in FIG. It is also possible to realize the advance angle function by the exhaust pressure only at the time of reverse, for example, by providing and linking with the operation of the count number control circuit 34.

Furthermore, by changing the time constant of the CR charging / discharging circuit of the pressure sensor output unit, it is possible to gradually reduce the output of the pressure sensor during rapid deceleration.

The case of the outboard motor has been described above, but the present invention is not limited to this, and can be generally used in an internal combustion engine in which the exhaust pressure changes greatly depending on the use condition.

〔The invention's effect〕

As described above, according to the present invention, in the outboard motor, the advance of the ignition timing is corrected by the exhaust pressure, so that it is possible to obtain the advancement characteristics according to the shift position and the water level, and to increase the exhaust pressure. Output can be prevented from decreasing.

Outboard motors have different mounting heights depending on the type of ship to be mounted, and therefore have different water levels and therefore different exhaust pressures. However, according to the present invention, the influence of the water level and the influence of the reverse can be detected by the exhaust pressure, an appropriate ignition timing can be set, and such a problem can be eliminated.

According to the present invention, such control can be easily performed by using a signal of an exhaust pressure sensor based on a conventional electric advance system such as ignition timing control based on a throttle opening.

Further, by combining with a shift position detection switch or the like, it is possible to correct only the target shift position. In this case, simple advance angle correction during acceleration can be performed without using a complicated control system.

[Brief description of the drawings]

FIG. 1 is a diagram showing the overall configuration of one embodiment of the present invention, FIG. 2 is a diagram showing the configuration of an ignition timing control system of one embodiment of the present invention,
FIG. 3 is a diagram showing the electrical configuration of the pressure detector, FIG. 4 is a diagram showing the relationship between the output voltage of the pressure detector and the pressure, and FIG. 5 is a diagram showing the relationship between the throttle opening and the output voltage of the pressure detector. Diagram,
FIG. 6 is a diagram showing output voltage characteristics of a count number control circuit;
FIG. 7 is a graph showing the ignition timing characteristics with respect to the throttle opening, FIG. 8 is a graph showing changes in the exhaust pressure and the number of revolutions during rapid acceleration and rapid deceleration, and FIGS. FIG. 10 is a diagram showing a schematic configuration of an outboard motor, FIG. 10 is a diagram showing an outline of an electric configuration of a conventional outboard motor, FIG. 11 is a diagram showing an example of a throttle characteristic, and FIG. 12 is an example of an ignition timing characteristic. FIG. 13 is a diagram showing the relationship between the water level, the shift position, the exhaust pressure, and the rotation speed. 9: Lead angle control device, 16: Throttle opening sensor, 36
…… Pressure detector.

Claims (3)

(57) [Claims] An exhaust tube extends downward in an exhaust chamber, and is exhausted from an air exhaust hole provided in the exhaust chamber or an underwater exhaust hole provided in a propeller shaft through the exhaust tube. The lower end of the exhaust tube is submerged when the water level in the exhaust chamber is high. The exhaust tube is used for an internal combustion engine for an outboard motor, and the ignition timing of the internal combustion engine is determined according to an output indicating a throttle opening from a throttle opening sensor. In the advance angle control device for controlling, a pressure detection unit for detecting an exhaust pressure in the exhaust chamber is provided,
An advance angle control device characterized in that the ignition timing is controlled to be advanced as the exhaust pressure detected by the pressure detection section is higher. 2. The ignition timing control device according to claim 1, wherein a shift position detection switch is provided, and based on an output of the shift position detection switch, the advance angle control device controls the ignition timing of the internal combustion engine. 2. The ignition timing control device according to claim 1. 3. The ignition timing control device according to claim 1, wherein the advance control device controls the ignition timing during acceleration.