JP2610803B2 - Ignition timing control internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition timing control internal combustion engine that controls ignition timing with optimal advance characteristics.

[Related Art] Generally, control of the ignition timing of an internal combustion engine has a great effect on fuel efficiency, internal combustion engine output, exhaust gas concentration, and the like. Conventionally, the ignition timing has been delayed during warm-up or acceleration reduction when a large amount of unburned gas is discharged, and the fuel consumption efficiency and output have been improved as normal advance characteristics during normal running. Also,
As an exhaust gas countermeasure, a technology has been developed in which the angle is normally advanced at a low temperature or a low load, while the angle is advanced at a high speed so that a trouble such as overheating of the internal combustion engine does not occur.

[Problems to be Solved by the Invention] However, since these are not precisely controlled according to the operating conditions of the engine, their effects have not been sufficient.

That is, in the internal combustion engine, the throttle opening is small in the low load range, and in the compression stroke in which the amount of fresh air is small, the density of the air-fuel mixture is low even when compressed, and the combustion speed is low. Has become.

Also, as the load increases, the amount of fresh air increases, and in the compression stroke, the density of the air-fuel mixture can be sufficiently increased,
The combustion speed increases, but if the amount of advance is too large, the proportion of combustion when the piston is before the top dead center increases, resulting in a decrease in output and a decrease in fuel consumption.

Further, at the time of idling, the engine speed is low, the intake stroke time is long, and the intake air amount does not decrease from the low load region, so that the density of the air-fuel mixture is equal and the combustion speed does not change. On the other hand, the amount of combustion per predetermined crank angle rotation increases due to the lower engine speed, that is, the combustion speed per crank rotation angle increases, the combustion ratio when the piston is before the top dead center increases, the output decreases, and the fuel consumption decreases. There are problems such as a decrease.

The present invention has been made in view of such circumstances, and provides an optimal ignition timing without always making the advance amount too small, and at a low cost to achieve a significant improvement in fuel efficiency and internal combustion engine output. It is an object to provide a controlled internal combustion engine.

[Means for Solving the Problems] In order to solve the above problems, an ignition timing control internal combustion engine of the present invention ignites by discharging an electric charge stored in an ignition capacitor and an ignition capacitor in response to an ignition start signal. An ignition circuit having a thyristor that generates an ignition spark in the plug, a selection output device that outputs a constant predetermined voltage signal according to the throttle opening, and a pulsar coil that outputs a voltage signal that changes according to the crank angle, The voltage signal from the pulsar coil and the predetermined voltage signal from the selection output device are received, and the timing of the crank angle when the voltage value of the voltage signal from the pulsar coil becomes the voltage value of the predetermined voltage signal from the selection output device And a comparator for outputting an ignition start signal to a thyristor of the ignition circuit. A continuous voltage characteristic with no inflection point from the maximum advance to the minimum advance, the crank angle increases as the crank angle increases in the range from the maximum advance to the minimum advance The predetermined voltage signal has a voltage characteristic in which the output voltage is maximized in a throttle opening range in an idling region, and is slightly larger than that at idle when the throttle opening is equal to or less than a predetermined opening. When
The output voltage is minimized, and the predetermined voltage signal is such that, in a region where the throttle opening is larger than the predetermined opening, the slope of the output voltage change with respect to the increase in the throttle opening is positive and the throttle opening increases. It is characterized in that the inclination is reduced.

Further, the ignition timing control internal combustion engine, the pulsar coil comprises a core and a winding wound around the core,
The core is rotatable about a rotation axis, and is disposed opposite to a magnet having an arcuate surface in the direction of rotation, and a minimum gap between the core tip and the arcuate surface of the magnet causes the magnet to rotate. The present invention is characterized in that the pulsar coil has the core tip inclined such that the magnet at the core tip that is closer to the magnet is larger than that at the core tip where the magnet moves away when rotating.

According to the present invention, the advance characteristic of the internal combustion engine is set such that the ignition timing is set to the maximum advance angle in a low load range in accordance with the throttle opening, and the advance amount is decreased as the load increases. ing.

That is, in the compression stroke where the throttle opening is small and the amount of fresh air is small in the low load range, the density of the air-fuel mixture is low and the combustion speed is slow even if compressed, so that the combustion can be completed by advancing it. It is possible to improve output and fuel efficiency. In particular, in a two-cycle internal combustion engine, the residual gas increases in a low load range, so that the density of the air-fuel mixture is reduced, the combustion speed is reduced, and the combustion can be completed. In addition, output improvement,
Fuel efficiency can be improved.

Also, as the load increases, the amount of fresh air increases, and in the compression stroke, the density of the air-fuel mixture can be sufficiently increased,
If the combustion speed becomes faster and the amount of advance is too large, the proportion of combustion when the piston is before the top dead center increases, the output decreases,
Although the fuel consumption is reduced, since the advance amount is reduced, the output and the fuel consumption can be improved without reducing the output and the fuel consumption.

However, since the engine speed increases as the throttle opening increases, even if the crank angle of the combustion expansion stroke after ignition is the same, the time of this combustion expansion stroke is short, and the amount of advance is small. If it is performed too much, the combustion will not be completed during the combustion expansion process, and the output will decrease and the fuel consumption will decrease. In the present invention, the advance amount is set to be at least larger than at the time of idling, and the output and the fuel efficiency can be improved without making the minute advance amount too small.

In addition, the advance angle characteristic of the internal combustion engine is set to the minimum advance amount in an idling region where the load is smaller than that in the low load region.

That is, when idling, the engine speed is low, the intake stroke time is long, and the amount of intake air is not reduced from the low load range, so that the density of the mixture is equal and the combustion speed does not change. On the other hand, the amount of combustion per predetermined crank angle rotation increases due to the lower engine speed, that is, the combustion speed per crank rotation angle increases, and in addition, the rotation crank angle per predetermined time is the maximum, and after ignition, The crank angle until the end of combustion is shorter,
Although the combustion ratio when the piston is located before the top dead center increases, the output decreases and the fuel consumption decreases. However, since the ignition timing is set to the minimum advance amount, the output reduction and the fuel consumption decrease can be more reliably prevented.

As described above, in the present invention, the advance amount is set to be at least larger than at the time of idling, and the output advance amount and the fuel efficiency can be improved without making the minute advance amount too small.

In addition, a voltage signal from the pulser coil and a predetermined voltage signal from the selection output device are received. When the throttle opening is equal to or larger than the predetermined opening, the slope of the output voltage change with respect to the increase in the throttle opening is always the same. As the degree increases, the inclination becomes smaller,
As the throttle opening increases, the rate at which the ignition timing is delayed can be reduced.

That is, as the throttle opening increases, the pressure of the supply air supplied to the combustion chamber increases. The flame propagation speed increases as the supply pressure increases, but the increase in the flame propagation speed becomes less sensitive as the supply pressure increases. Therefore, as the throttle opening increases, the proportion of delaying the ignition timing is reduced, so that the ignition is performed in accordance with the insensitivity of the increase in the flame propagation speed, and the engine output can be increased. That is, above the predetermined opening, a large output is always obtained according to the throttle opening.

Further, as the crank angle increases in the range from the maximum advance to the minimum advance of the voltage signal from the pulsar coil, it has a voltage characteristic in which the voltage increase with respect to the crank angle increase increases. Can easily match the ignition timing with the required advance amount in accordance with the increase.

Further, a voltage signal corresponding to a change in the crank angle is output from the pulsar coil, and the thyristor is triggered at the moment when the voltage signal reaches a predetermined voltage, so that the responsiveness is good. Further, since it is not necessary to previously store the voltage characteristics, the ignition timing control device can be configured at low cost.

In addition, the pulsar coil includes a core and a winding wound around the core, and the core is disposed to face a magnet having an arcuate surface in a rotational direction, and a minimum gap between the core tip and the arcuate surface of the magnet is provided. However, when rotating the magnet, the core tip is inclined so that the one at the core tip where the magnet approaches is larger than the one at the core tip where the magnet moves away, and the structure is simple with only the core shape of the pulsar coil. In addition, it is possible to provide the advance angle characteristics required of the internal combustion engine at low cost.

Hereinafter, an embodiment of an ignition timing control internal combustion engine according to the present invention will be described in detail with reference to the accompanying drawings.

The present invention provides a load detecting means for detecting a load of an internal combustion engine, for example, a potentiometer for measuring a throttle valve opening of a carburetor, and detects a potentiometer output signal and a crank angle of the internal combustion engine, for example, a pulsar coil. The ignition timing is controlled based on the signal from the controller.

FIG. 1 is a schematic view of a two-stroke internal combustion engine to which the present invention is applied.

In the figure, reference numeral 1 denotes a potentiometer as load detecting means, which is attached to a carburetor 2 for measuring the opening of a throttle valve. 3 is a crank angle sensor for detecting the crank angle of the internal combustion engine, 4 is an ignition timing control circuit for controlling the ignition timing, 5 is an ignition circuit composed of a well-known CDI, 6 is an ignition coil thereof, and 7 is an ignition circuit. Plug.

The ignition circuit 5 is configured as shown in detail in FIG.
It has an ignition capacitor 105b and a thyristor 105c that generates an ignition spark in the ignition plug 7 via the ignition coil 6 by discharging an electric charge stored in the ignition capacitor 105b in response to an ignition start signal.

Further, the ignition timing control circuit 4 is configured as shown in detail in FIGS. 8 and 9, and outputs a predetermined output voltage signal in accordance with the throttle opening from the potentiometer 1; A pulser coil 44 that outputs a voltage signal from the crank angle sensor 3 that changes according to the crank angle.
And the voltage signal from the pulsar coil 44 and the selection output device 20
When the ignition circuit 5 receives the predetermined voltage signal from 0 and the crank angle when the voltage value of the voltage signal from the pulsar coil 44 becomes the voltage value of the predetermined voltage signal from the selection output device 200.
201 that outputs an ignition start signal to the thyristor 105c
It consists of

FIG. 2 is a schematic view showing an example in which the intake pipe negative pressure detection sensor 8 is used as load detection means for detecting the load of the internal combustion engine.
The other configuration is the same as that of FIG.

3 and 4 show the potentiometer 1 shown in FIG.
FIG. 2 is a front sectional view and a side sectional view showing a specific example in which is attached to a variable venturi vaporizer 2.

As shown in the figure, a rotary potentiometer 1 is mounted on a cap 31 of a carburetor 2 having a sliding throttle valve.
In this case, it is economical to newly form only the cap portion 31. An end of a throttle wire 32a connected to a throttle grip (not shown) is a rotary potentiometer 1
Of the rotary potentiometer 1
The sliding throttle valve 33 is connected to the sliding throttle valve 33 via a connection wire 32b having one end wound around the pulley 1a. The pulley 1a is directly connected to the rotary shaft 1b of the potentiometer 1, and this pulley 1a
Is returned to the original position by the coiled spring 1c.

Operate the throttle grip to operate the throttle cable 32
When a is pulled, the throttle valve 33 opens the venturi diameter and the intake passage against the elastic force of the spring 34 by the connecting wire 32b via the potentiometer 1. Thereby, the jet needle 35 is pulled, and the opening area of the main nozzle is adjusted. The rotary potentiometer 1 rotates according to the movement (stroke) of the throttle cable 32a,
The voltage corresponding to the rotation angle is supplied to the ignition timing control circuit 4 as a throttle potentiometer output. Note that if the ignition timing control circuit 4 is configured so that a slight change in the throttle opening during idling can be ignored, the deflection of the throttle wire 32a and the connection wire 32b is allowed.

FIG. 5 shows the configuration of the crank angle sensor 3 provided for detecting the crank angle.
For example, other reactance sensors, optical sensors, oscillation sensors, magnetic sensors, and the like can be used.

A core 43 is attached to the inner peripheral surface of the flywheel 41 that rotates about the rotation shaft 40, in opposition to magnets 42 provided at predetermined intervals, and a wire is wound therearound to form a pulsar coil 44. I have. The width of the tip (magnetic detection unit) of the core 43 is wider than the interval between the magnets 42, and the shape of the tip is asymmetrical such that the left side of the magnetic flux becomes narrower with the magnet 42 during left rotation, for example. I have.

That is, the pulsar coil 44 includes a core 43 and a winding 44a wound around the core 43.The core 43 is disposed so as to face the magnet 42 having an arcuate surface in the rotational direction. The minimum gap D1 between the arc-shaped surface 42a is
When rotating the magnet 42, the core tip 43 that is away from the magnet 42
Core tip 43 closer to magnet 42 than in a1
The tip end 43a of the core is inclined so as to be larger in a2, and the advanced angle characteristic required for the internal combustion engine can be provided simply and inexpensively only by the core shape of the pulsar coil 44.

In general, when controlling the ignition timing, the output characteristic of the pulsar coil 44 changes from the maximum advance to the minimum advance as shown in FIG. A continuous characteristic without the above is obtained by the above configuration. That is, as described in detail below with reference to FIGS. 6 to 14,
The ignition timing control circuit 4 determines that the voltage signal from the pulsar coil 44 has a continuous voltage characteristic with no inflection point from the maximum advance to the minimum advance and the crank angle from the maximum advance to the minimum advance. As the crank angle increases in the range, the voltage characteristic has a voltage characteristic in which the amount of voltage increase with respect to the amount of crank angle increase is large. When the throttle opening is slightly larger than the idling when the opening is equal to or less than the opening, the output voltage is minimized, and the predetermined voltage signal is, as shown in FIG. 12, in a region where the throttle opening is larger than the predetermined opening, as shown in FIG. The slope becomes smaller as the slope of the output voltage change with respect to the increase in the opening is positive and the throttle opening increases.

Thus, in the ignition timing control circuit 4, the pulsar coil
The voltage signal from the selector 44 and the predetermined voltage signal from the selection output device 200 are received. The predetermined voltage signal is such that when the throttle opening is equal to or more than the predetermined opening, the slope of the output voltage change with respect to the increase in the throttle opening is positive and As the throttle angle increases, the rate of delaying the ignition timing can be reduced as the throttle opening increases.

That is, as the throttle opening increases, the pressure of the supply air supplied to the combustion chamber increases, and as the supply pressure increases, the flame propagation speed increases, but as the supply pressure increases, the flame propagation speed increases. Becomes less intuitive, so as the throttle opening increases,
By reducing the ratio of delaying the ignition timing, the ignition is performed in accordance with the insensitivity of the increase in the flame propagation speed, and the engine output can be increased. That is, above the predetermined opening, a large output is always obtained according to the throttle opening.

Further, as the voltage signal from the pulsar coil 44 increases in crank angle in the range from the maximum advance to the minimum advance, there is a voltage characteristic in which the voltage increase with respect to the crank angle increase increases. As the angle increases, the ignition timing can be easily matched to the required advance amount.

 Hereinafter, the control of the ignition timing will be described in detail.

In the present invention, the ignition timing is optimally set according to the load condition by giving the throttle opening and the ignition timing characteristics as shown in FIG.
The aim is to improve the output of the internal combustion engine. That is, the load (throttle opening) is divided into five areas, 1; idling area, 2; first load area, 3; second load area, 4; third load area, 5; The ignition timing is set according to the ignition timing, the advancement characteristic of the internal combustion engine is set, the ignition timing is set at the maximum advancement in the low load range according to the throttle opening, and the advancement amount is decreased with the load increase. Like that.

That is, in the low load range of the first load range, the throttle opening is small, and in the compression stroke in which the amount of fresh air is small, the density of the air-fuel mixture is low even if it is compressed, and the combustion speed is low. Combustion can be completed, and output and fuel economy can be improved. In particular, in the case of a two-cycle internal combustion engine, the residual gas increases in a low load region, so that the density of the air-fuel mixture is reduced, the combustion speed is reduced, and the combustion can be completed. However, the output can be improved and the fuel efficiency can be improved.

In addition, the amount of fresh air increases as the load increases, such as 3; the second load region, 4; the third load region, 5; the fourth load region, and the density of the air-fuel mixture can be sufficiently increased in the compression stroke. However, if the combustion speed increases and the advance amount is too large, the proportion of combustion when the piston is before the top dead center increases, resulting in a decrease in output and fuel consumption, but since the advance amount is small, Thus, the output can be improved and the fuel efficiency can be improved without lowering the output and the fuel efficiency.

In addition, the advance angle characteristic of the internal combustion engine is set to a minimum advance amount in 1; an idling region where the load is smaller than in the low load region of the first load region.

That is, when idling, the engine speed is low, the intake stroke time is long, and the amount of intake air is not reduced from the low load range, so that the density of the mixture is equal and the combustion speed does not change. On the other hand, the amount of combustion per predetermined crank angle rotation increases due to the lower engine speed, that is, the combustion speed per crank rotation angle increases, the combustion ratio when the piston is before the top dead center increases, the output decreases, and the fuel consumption decreases. However, since the ignition timing is set to the minimum advance amount, a decrease in output and a decrease in fuel consumption can be prevented.

FIG. 8 shows one specific example of a circuit for obtaining the ignition timing according to the load as shown in FIG.

In FIG. 8, reference numeral 81 denotes a comparator, 82 denotes a buffer amplifier, and 83 denotes an operational amplifier that functions as an operation amplifier. The throttle opening signal is obtained as the output of a potentiometer (variable resistor 84 and its movable contact is D) shown in FIGS. 4 and 5, and is obtained from the pulser coil 44 of the crank angle sensor 3 in FIGS. 4 and 5. Is the crank angle signal of A
Given to points.

The voltage signal at the point A is integrated by the capacitor 85,
The voltage is divided by the resistors 86a and 86b and the voltage
Supplied to 7.

On the other hand, the voltage signal A passes through the diode 88 and is integrated by the resistor 89 and the capacitor 90 to obtain a voltage signal C at a point C, which becomes another input basic voltage signal of the comparator 87. The reason why the voltage signal A is integrated by the two circuits in this manner is to absorb the variation in the gap between the core 43 and the magnet 41 in FIG. 5 (attributable to the variation in the pulser output). Here, reference numeral 91 denotes a constant voltage diode.

The voltage signal C is divided by the resistors 92 and 93 to obtain a voltage signal G. The voltage signal G is input to one terminal of the operation amplifier 83 via the resistor 94 of the buffer amplifier 82. On the other hand, the voltage signal D corresponding to the throttle opening is input to the positive terminal of the operation amplifier 83 and is input to the negative terminal of the comparator 81. The voltage signal C is connected to the + terminal of the comparator 81 with a resistor 95.
And the voltage signal E of the divided voltage signal divided at 96 is supplied. The output of comparator 81 passes through diode 97
Supplied to 87. The output of the operational amplifier 83 is connected in parallel with the diode 97 via diodes 98 and 99 connected in reverse directions, and is supplied to a comparator 87. Diode 98
The resistors 100 and 101 are connected to the anode side of the
Is applied. Further, resistors 102 and 103 are connected in parallel to the operation amplifier 83 and the diode 98, respectively. A resistor 104 is connected between the cathode of the diode 97 and the resistor 99 and the ground. In the comparator 87, the voltage signal B
And the selected outputs of the diodes 97 and 99 are compared. As a result, an ignition timing voltage signal is supplied to the ignition circuit 105 at the timing of the intersection of the crank angle voltage signal and the selected output, and the ignition is performed. This ignition circuit 105 is well known, and includes an ignition coil 6, an ignition plug 7, a rectifier diode 105a, an ignition capacitor 10
5b, a thyristor 105c. The thyristor 105c conducts at a predetermined ignition timing, discharges the charge in the ignition capacitor 105b, and generates an ignition spark in the ignition plug 7. Note that the resistor 106 is a resistor that detects disconnection of the coupler or disconnection.

Further, a voltage signal corresponding to a change in the crank angle is output from the pulsar coil 44. The voltage signal triggers the thyristor 105c at the moment when the voltage signal reaches a predetermined voltage, and the response is good. Further, since it is not necessary to store the voltage characteristics in advance, the ignition timing control device can be configured at low cost.

FIG. 9 shows the circuit of FIG. 8 by functional blocks. FIG. 10 shows the relationship between the crank angle voltage signal (voltage signal B), the nine selected outputs of the diodes 97 and 9, and the ignition timing.

Next, as shown in FIG. 7, the operation of the circuit of FIG. 8 will be sequentially described for each region of the throttle opening (load).

1 Idling region: Since the throttle opening is substantially zero, the voltage signal D is substantially at the ground potential, smaller than the voltage level of the voltage signal E due to the voltage division, and the output F of the comparator 81 is the same voltage level as the voltage level of the voltage signal E. Becomes On the other hand, in this state, the voltage signal G
If the ratio between the voltage dividing resistor 92 and the resistor 93 is selected so that the voltage becomes larger than the voltage signal D, the output of the diode 99 becomes zero because the operating amplifier 83 becomes zero. As an output, a voltage signal E of a constant voltage level is obtained and supplied to the comparator 87.

Based on FIG. 10, the ignition timing in this state is shown in FIG.
The result is as shown in FIG. In this case, since the selected output voltage level is high, a constant small advance angle can be obtained as shown in a region 1 in FIG.

2 1st load range; Since the throttle is a little more open than at idle, the potentiometer output D has a certain value, and the ratio of the resistance 95 and the resistance 96 is selected so that the voltage signal becomes D> E in this state. Then, the output F of the comparator 81 becomes zero, and the output of the diode 97 also becomes zero. On the other hand, if the ratio between the resistors 92 and 93 is selected so that the voltage signal satisfies G> D, the output of the operating amplifier 83 becomes zero and the output of the diode 99 also becomes zero. Therefore, the selected output of the diodes 97 and 99 is substantially zero (however, the potential difference of the diodes is actually 0.6 V).
As shown in FIG. 11 (b), the ignition timing is advanced and the advance angle has a constant value.

3 2nd load area; Since the throttle opening is further increased, the voltage signal D
Rises, and the output F of the comparator 81 becomes zero. On the other hand, in this state, since the voltage signal becomes G <D, the operational amplifier 83 functions as an operational amplifier, and the level of the output voltage H is output voltage level = (voltage D level−voltage G level) × (the resistance of the resistor 94). (Resistance value + resistance value of resistance 102) / resistance value of resistance 94.

In this state, if the voltage dividing ratio of the voltage dividing resistors 100 and 101 is selected so that the voltage signal I becomes higher than the voltage levels of the voltage signals H and J, the voltage signal I drops through the diode 98, and as a result, the voltage Signal I and voltage signal H have the same voltage level. Therefore, the output of the diode 99 is the same as the voltage signal H. This voltage signal H increases and decreases in proportion to the throttle opening (voltage signal D) which is an intermediate voltage level as shown in FIG. 11 (c), and the ignition timing is delayed from the range 2 and becomes a small advance angle. The advance angle characteristic at this time decreases proportionally as shown by the three regions in FIG.

4. Third load region: When a load is further applied and the throttle opening increases, the voltage level of the voltage signal D approaches the voltage level of the voltage signal C. The output of the comparator 81 is still zero, but the output of the operational amplifier 83 is the same as in the idle state of 3 Output voltage H level = (voltage D level−voltage G level) × (resistance value of resistor 94 + resistance of resistor 102) Value) / resistance value of the resistor 94. At this time, since the voltage signal H becomes higher than the voltage level of the voltage signal I, the diode 98 is turned off, and the voltage signal H works to increase the voltage level of the voltage signal I via the resistor 103, and therefore the diode The output of 99 is higher than the voltage signal J in the first load region.
At this time, the rate of increase of the voltage signal J with the increase of the throttle opening becomes smaller than the rate of increase in the first load region as shown in FIG. 11 (d). It becomes a proportional part with a small inclination like a three load area.

5 Fourth load area; When the load is further increased and the throttle is greatly opened compared to the state of the third load area 4, the voltage signal H becomes equal to the voltage level of the voltage signal C, does not rise any more, and becomes a constant value. Become. At this time, the voltage level of voltage signal J is a relatively high constant value corresponding to the voltage level of voltage signal C, as shown in FIG. Therefore, the region 5 shown in FIG. 7 is obtained, and the advance angle becomes small.

FIG. 12 shows the change in the voltage level of the voltage signal of each section under the load conditions of each of the regions 1 to 5 described above.

In the above description, the advance angle characteristic is determined according to the load (throttle opening). However, the internal combustion engine may require the advance angle characteristic corresponding to each (application). For example, there is an internal combustion engine that requires an advance angle to increase when the rotation speed increases, and a retard direction to control when the rotation speed is low. In the present invention, the capacitor 90
And the integration time constant of the integration characteristics based on 85.
By doing so, a larger advance angle can be given at high speed than at low speed.

FIG. 13 shows the relationship between the throttle opening and the ignition timing of the carburetor obtained in this manner at high speed and at low speed.

FIG. 14 shows the relationship between the rotation speed of the internal combustion engine and the ignition timing,
The throttle opening of the carburetor is shown as a parameter. Although the present invention is preferably used for a two-cycle internal combustion engine, it goes without saying that a similar effect can be obtained with four cycles.

[Effect of the Invention] As described above, the present invention sets the advancement characteristics of the internal combustion engine, the ignition timing according to the throttle opening at the maximum advancement in a low load range, and increases the advancement amount with the load increase. By setting so as to lower, an optimal advance angle can always be given according to the load applied to the internal combustion engine, and at least the advance amount is set larger than at the time of idling, and this minute advance amount is set. The output and fuel efficiency of the internal combustion engine are improved without being made too small.

Furthermore, when idling, the engine speed is low, the intake stroke time is long, and the amount of intake air does not decrease from the low load range, so that the density of the air-fuel mixture is equal and the combustion speed does not change. On the other hand, the amount of combustion per predetermined crank angle rotation increases due to the lower engine speed, that is, the combustion speed per crank angle rotation increases, and in addition, the rotation crank angle per predetermined time becomes the maximum, and The crank angle until the end of combustion is shortened, and the combustion ratio when the piston is before the top dead center is further increased, the output is reduced, and the fuel consumption is reduced, but the ignition timing is set to the minimum advance amount As a result, it is possible to more reliably prevent a decrease in output and fuel consumption.

As described above, in the present invention, since the advance amount is set to be at least larger than at the time of idling, the output advance amount and the fuel consumption can be improved without making the minute advance amount excessively small.

In addition, a voltage signal from the pulsar coil and a predetermined voltage signal from the selection output device are received. When the throttle opening is equal to or larger than the predetermined opening, the slope of the output change with respect to the increase in the throttle opening is the same as the throttle opening. As the throttle opening increases, the rate at which the ignition timing is delayed can be reduced, and as the throttle opening increases, the ignition timing is delayed at a higher rate. , The ignition is performed in accordance with the insensitivity of the increase in the flame propagation speed, the engine output can be increased, and above a predetermined opening, a large output is always obtained according to the throttle opening. .

Further, as the voltage signal from the pulsar coil has a voltage characteristic in which the voltage increase with respect to the crank angle increase becomes larger as the crank angle increases in the range from the maximum advance to the minimum advance, The ignition timing can be easily matched to the required advance amount as the angle increases.

Also, a voltage signal corresponding to the change in the crank angle is output from the pulsar coil, and the thyristor is triggered when the voltage signal reaches a predetermined voltage. Since there is no need to store in advance, an ignition timing control device can be configured at low cost.

In addition, the pulsar coil includes a core and a winding wound around the core, and the core is disposed to face a magnet having an arcuate surface in a rotational direction, and a minimum gap between the core tip and the arcuate surface of the magnet is provided. However, when rotating the magnet, the core tip is tilted so that the one at the core tip where the magnet approaches is larger than the one at the core tip where the magnet moves away, so the structure is only the core shape of the pulsar coil. It is possible to easily and inexpensively provide the advance angle characteristics required of the internal combustion engine.

[Brief description of the drawings]

1 and 2 are schematic diagrams of an ignition timing control internal combustion engine to which the present invention is applied, FIG. 3 is a front sectional view showing a specific example of detecting a throttle opening of a carburetor of the present invention, and FIG. Similarly, a side sectional view, FIG. 5 is a specific configuration diagram of crankshaft angle signal detection, FIG. 6 is a voltage signal diagram obtained in FIG. 5, and FIG. 7 is a characteristic showing a preferable relationship between a throttle opening and ignition timing. FIG. 8 is a specific circuit diagram for obtaining the characteristics shown in FIG. 7, FIG. 9 is a functional block diagram thereof, and FIG. 10 is a diagram showing the relationship between the crank angle voltage signal, the ignition control voltage signal and the ignition timing. 11 (a) to 11 (e) show the relationship between the crank angle voltage signal, the ignition control voltage signal and the ignition timing according to each load condition, and FIG. 12 shows each part in each region of FIG. FIGS. 13 and 14 show changes in the voltage level of the voltage signal. FIG. 9 is an advance characteristic diagram when the advance characteristic is changed according to the rotation speed. DESCRIPTION OF SYMBOLS 1 ... Potentiometer, 2 ... Vaporizer 3 ... Crank angle sensor 4, ... Ignition timing control circuit 5 ... Ignition circuit 8 ... Intake pipe negative pressure detection pressure sensor

Claims (2)

(57) [Claims] An ignition circuit having an ignition capacitor, a thyristor that generates an ignition spark in an ignition plug by discharging an electric charge stored in the ignition capacitor in response to an ignition start signal, and a throttle opening degree. A selection output device that outputs a constant predetermined voltage signal, a pulsar coil that outputs a voltage signal that varies according to the crank angle, and a pulsar coil that receives a voltage signal from the pulsar coil and a predetermined voltage signal from the selection output device. An ignition timing control circuit comprising: a comparator for outputting an ignition start signal to a thyristor of the ignition circuit at a timing of a crank angle when a voltage value of a voltage signal from the selector becomes a voltage value of a predetermined voltage signal from the selection output device. The voltage signal from the pulsar coil has a continuous voltage characteristic with no inflection point from the maximum advance to the minimum advance, More corners crank angle increases in a range from the maximum advance angle until the minimum advance angle has a larger voltage characteristic of the voltage increment with respect to the crank angle increment,
The predetermined voltage signal is such that the output voltage is minimized when the output voltage is maximized in the idling region and the throttle opening is slightly larger than at idle when the throttle opening is equal to or less than the predetermined opening. The signal is in a region where the throttle opening is larger than the predetermined opening.
An ignition timing control internal combustion engine characterized in that the gradient decreases as the slope of the output voltage change with respect to the increase in the throttle opening increases and the throttle opening increases. 2. The pulsar coil according to claim 1, wherein the pulsar coil includes a core and a winding wound around the core. The core is rotatable about a rotation axis, and is disposed to face a magnet having an arcuate surface in the direction of rotation. Wherein the minimum gap between the core tip and the arcuate surface of the magnet is smaller at the core tip where the magnet is closer than at the core tip where the magnet moves away when rotating the magnet. The ignition timing control internal combustion engine according to claim 1, further comprising the pulsar coil in which the tip of the core is inclined so as to increase.