JPH0237155A - Controlling apparatus for output of internal combustion engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an output control device for an internal combustion engine, and particularly when the air-fuel ratio of the air-fuel mixture supplied to the engine becomes lean and the engine is in a predetermined operating state. The present invention relates to a control device that appropriately reduces engine output.

(Prior art and problems to be solved by the invention) In a conventional internal combustion engine, the fuel in the fuel tank (
When the amount of remaining fuel (hereinafter referred to as "residual fuel J") decreases to a so-called gas-depletion state, or when the accelerator opening becomes extremely small and the amount of intake gas decreases, the desired amount of fuel is supplied to the engine. As the amount decreases, the air-fuel ratio of the air-fuel mixture becomes leaner, and the piston cooling effect of the fuel is significantly reduced. On the other hand, when the engine is in a high output/high rotation state, the temperature of the piston tends to rise, and this tendency is particularly noticeable in recent high output/high rotation engines. For this reason, when the engine is in a high output and high rotation state, and the air-fuel ratio of the air-fuel mixture is lean as described above, the piston temperature tends to rise excessively, combined with the decrease in the cooling effect described above. The toughness of the piston decreases due to this.

The present invention has been made in order to solve the above-mentioned problems of the conventional technology, and provides an output control device for an internal combustion engine that can prevent an excessive rise in piston temperature and improve the toughness of the piston. With the goal.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes an air-fuel ratio detecting means for detecting that the air-fuel ratio of the air-fuel mixture supplied to the engine has become lean, and a rotation speed detecting means for detecting the engine speed. a rotation speed determination means for determining that the engine rotation speed detected by the rotation speed detection means is equal to or higher than a predetermined rotation speed; The engine is equipped with an output reduction means for reducing the output of the engine.

(Example) An example of the present invention will be described below with reference to the drawings.

First, in FIGS. 1 and 2, the reference numeral 1 indicates a two-cycle engine mounted on the motorcycle 2, and a first engine that protrudes upward from the crankcase 3 and toward the front of the vehicle, respectively.
and second cylinder blocks 41 and 42.

Since the structures of both cylinder blocks 41 and 42 are basically the same, only the structure of the cylinder block 41 of cylinder 1 will be described below.

A piston 6 is slidably fitted into the cylinder hole 5 of the cylinder block 41. The piston 6 is connected to a crankshaft 7 supported by the crankcase 3. Further, a cylinder head 8 is attached to the upper end of the cylinder block 41, and defines a combustion chamber 9 between the cylinder head 8 and the upper surface of the piston 6. An ignition plug lO is screwed onto the cylinder head 8 with an electrode facing into the combustion chamber 9. The ignition plug lO is connected to a control unit 29 (FIG. 4), which will be described later, to control its ignition operation, that is, the ignition timing θi.
g etc. are controlled.

A carburetor II is installed in the crank chamber 3a inside the crankcase 3 via a reed valve (not shown),
During the upward stroke of the piston, air-fuel mixture is supplied from the carburetor 11 to the crank chamber 3a.

Further, reference numeral 12 in FIG. 1 is a fuel tank for storing combustion, and a first thermistor 1 is installed at the bottom of the fuel tank 12.
3 and a second thermistor 14 as a fuel remaining amount detection means.
is provided. The detection section of the second thermistor 14 is arranged at a lower position than that of the first thermistor 13.

Further, the inner wall of the cylinder hole 5 is provided with the crank chamber 3a.
A scavenging boat 15 communicating with the exhaust pipe 16 and an exhaust boat 17 communicating with the exhaust pipe 16 are opened, and these boats 15 and 17 are opened and closed by the peripheral wall of the piston 6.

The exhaust boat 17 is provided with a control valve 18 for controlling the opening/closing timing of the boat 17, that is, the exhaust timing. The control valve 18 is composed of a pair of plate-shaped flaps 19 and 19, as shown in FIG.
9.19 is disposed at the center of the cylinder hole 5 side opening of the exhaust boat 17 so as to sandwich a reinforcing wall 20 connecting the upper and lower walls thereof. In addition, the flap 19.1
The base ends of the valve shafts 9 abut against each other behind the reinforcing wall 20 and are fixed to a valve shaft 21 rotatably supported by the cylinder block 4 .

Furthermore, the distal end surface of the flap 19.19 is formed into an arcuate surface so as to be continuous with the inner circumferential surface of the cylinder hole 5.

The control valve 18 configured in this way has a valve shaft 21.
Due to the rotation of the exhaust boat 17, the position is moved to the fully open position stored in the storage recess 22 (FIG. 2) connected to the upper edge of the opening on the cylinder hole 5 side of the exhaust boat 17, and to the upper edge of the opening on the cylinder hole 5 side of the exhaust boat 17. It can be moved between a fully open position (state a in FIG. 2) where a specified amount of exposure is achieved.

An operating lever 23 is fixed to the outer end of the #1ll121, and the operating lever 23 is connected to a servo motor 2 which can rotate in forward and reverse directions via a valve opening wire 24 and a valve closing wire 25.
6 (Fig. 4). Therefore, by rotating the servo motor 26 in the forward or reverse direction, the control valve 18
The opening degree θ, that is, the exhaust timing can be controlled.

FIG. 4 shows the overall configuration of an engine output control device according to the present invention.

The first thermistor 13 is connected in series with a warning light 27, and this series circuit is connected to a battery 28 in reverse series to the second thermistor 14.

The second thermistor 14 is connected to a fuel amount detection circuit 30 of the control unit 29.

The control unit 29 includes the fuel amount detection circuit 30 and the rotation speed detection circuit 31 . A/D converter 38. Central processing unit (hereinafter referred to as rcPUJ) 32 and drive circuits 33 and 34
Consists of etc. One end of the resistor R1 of the fuel amount detection circuit 30 is connected to the second thermistor 14, and the other end is connected to the capacitor C1 and the base of the switching transistor Trl. The emitters of the capacitor C1 and the transistor Tr1 are both grounded. Further, the collector of the transistor Trs is connected to the battery 35 and also to the CPU 32 via a resistor R2.

On the other hand, the rotation speed detection circuit 31 is configured in exactly the same manner as the fuel amount detection circuit 30, and the resistance R3 on the input side thereof is as follows.
Engine rotation speed sensor (hereinafter referred to as r) as a rotation speed detection means
The resistor R4 on the output side is connected to the CPU 32. Note that the Ne sensor 36 can be configured using an ignition pulse.

Further, the A/D converter 38 is connected to a throttle valve opening sensor 39 as an accelerator opening detection means and the CPU.
32. The throttle valve opening sensor 39
is composed of a variable resistor whose resistance changes according to the opening degree θT11 of a throttle valve (none of which is shown) that is linked to the accelerator, and a constant voltage VB is supplied from a battery (not shown).

The CPU 32 calculates the engine rotation speed Ne according to the signal P2 from the rotation speed detection circuit 31, and also calculates the calculated engine rotation speed Ne and the fuel amount detection circuit 30.
The signal P1 from the A/D converter 38 and the signal P from the A/D converter 38
3, it is determined whether the conditions for reducing the output of the engine l are satisfied according to the control program described later (FIGS. 5, 7, and 8), and the ignition timing is adjusted according to the determination result. θig and the opening degree θex of the control valve 18 are calculated. Further, the CPU 32 transmits a drive signal based on the calculation result to the ignition device 3 including the spark plug 10 via the drive circuits 33 and 34.
7 and the servo motor 26 to drive them. That is, the CPU 32 constitutes a rotation speed determining means and an output reducing means in this embodiment.

Next, the operation of the engine output control device having the above configuration will be explained.

When the amount of remaining fuel, that is, the amount of fuel in the fuel tank 12 is large, both the first and second thermistors 13 and 14 are located below the liquid level of the fuel and are cooled by the fuel, so their temperature is low. The resistance value remains high. Therefore, since the amount of current flowing through the warning light 27 is small, the warning light 27 does not light up, and the base voltage of the switching transistor Trx is low and the transistor Trr is maintained in an off state, so that the fuel amount detection circuit 3o is transferred to the CPU 32. The output signal Pl of becomes high level.

Next, when the remaining fuel amount decreases as the engine l operates and reaches a preset first predetermined amount, the first thermistor 13 disposed at a higher position than the second thermistor 14
is first exposed on the surface of the fuel and is no longer cooled by the fuel, so its temperature rises and its resistance value decreases. As the amount of current flowing through the warning light 27 increases accordingly, the warning light 27 is turned on to warn the driver that the amount of remaining fuel is low.

When the amount of remaining fuel further decreases and reaches a second predetermined amount, the second thermistor 14 is also exposed above the fuel level, and its resistance value becomes smaller, turning on the transistor Trx. The output signal P1 becomes low level.

As described above, the output signal P1 from the fuel amount detection circuit 30 to the CPU 32 is switched to a high level when the remaining fuel amount is greater than the second predetermined amount, and to a low level when it is less than the second predetermined amount.

On the other hand, the rotation speed detection circuit 31 is supplied with a pulse signal synchronized with the rotation of the engine 1 from the Ne sensor 36, and the transistor Tr2 is turned on every time the signal is supplied, so that the output signal P2 to the CPU 32 is It becomes a low level at a frequency according to the rotation speed of l. The CPU 32 calculates the engine rotation speed Ne by counting the number of times this output signal P2 becomes low level.

Further, the A/D converter 38 converts the throttle valve opening f9T1+ from the throttle valve opening sensor 39, that is, a voltage signal corresponding to the accelerator opening of the vehicle, into a digital signal and supplies it to the CPU 32 as an output signal P3.

FIG. 5 shows a flowchart of a subroutine executed by the CPU 32 to control the ignition timing θjg according to the remaining fuel amount and the engine rotational speed Ne. First step 5
At step 01, it is determined whether the output signal Pl from the fuel amount detection circuit 30 is at a high (Hi) level. If the answer to this question is negative (No), that is, the output signal P1 is at a low level, and therefore the remaining fuel amount is less than or equal to the second predetermined amount, then the engine rotation speed Ne is set to the first predetermined rotation speed Nl (for example, 10
, OOOrpm) or more (step 502). This first predetermined rotation speed Ns is equal to the second predetermined rotation speed Ns described later.
The predetermined rotational speed N2 is set to a value such that when the engine I is operated up to both rotational speeds, its output becomes maximum and the temperature of the piston 6 reaches its maximum value.

The answer to step 502 is affirmative (Yes), that is, Ne≧
When Nl is established, it is determined whether or not the engine rotational speed Ne is less than or equal to a second predetermined rotational speed N2 (for example, 12.00 Orpm) (step 503).

When the answer is affirmative (Yes), that is, when N+≦Ne≦N2 holds true, the ignition timing θig is retarded (step 504), and this subroutine ends.

FIG. 6 shows an example of a table applied to retard the ignition timing θig. That is, step 504 above
By executing , the ignition timing θig is set at a predetermined angle Δθ
ig is set to a lower value (dashed line). As is well known, when the ignition timing θig is retarded with respect to the optimum ignition timing Oig', the engine output decreases and the piston temperature decreases.

Therefore, as mentioned above, by controlling the ignition timing to the retarded side in a predetermined engine speed range where the remaining fuel amount is small and the output of engine I is maximum, the engine output at this time can be adjusted appropriately. This makes it possible to prevent the temperature of the piston 6 from rising excessively and improve its toughness. Further, since the desired drivability cannot be obtained due to the reduction in engine output, the driver can sense this and be informed that the amount of fuel has decreased, thereby reliably preventing fuel exhaustion.

The answer to step 501 is affirmative (Yes), that is, the remaining fuel amount is greater than the second predetermined amount, or the answer to step 502 or 503 is negative (NO), that is, Ne
When (Nt or Ne)N2 is established, this subroutine is immediately terminated. That is, in this case, the optimum ignition timing θig l shown by the solid line in FIG. 6 is applied as is without retarding the ignition timing O1g.

FIG. 7 shows a flowchart of a subroutine executed by the CPU 32 to control the ignition timing O1g according to the throttle valve opening θT11 and the engine speed Ne. This subroutine differs from the subroutine in FIG. 5 only in the execution content of step 701, which corresponds to step 501.

That is, in step 701, it is determined whether the output signal P3 corresponding to the throttle valve opening θTl+ from the Δ/D converter 38 is less than or equal to a predetermined opening Or++o (for example, 5% of the full opening). This answer is negative (No), that is, P 3>
When OT110 is established, this subroutine is ended, and if it is affirmative (Yes), that is, the throttle valve opening θ is
When TI+ is extremely low, steps 702 to 704 are executed in exactly the same way as steps 502 to 504 in the subroutine of FIG. 5 described above.

As mentioned above, when the throttle valve opening degree θT11 is extremely small, the air-fuel ratio of the air-fuel mixture becomes lean due to the small intake gas amount, and the temperature of the piston 6 tends to rise. Similar to the subroutine shown in the figure, it is possible to prevent the temperature of the piston 6 from rising excessively and improve its toughness.

FIG. 8 shows a flowchart of a subroutine executed by the CPU 32 to control the opening Oex of the control valve 18.

First, in step 801, step 5 in FIG.
Similarly to 01, it is determined whether the output signal P+ is at a high level or not, and if the answer is negative (No), the engine rotation speed Ne is set to a third predetermined rotation speed N3 (for example, 0.800 rpm).
m) Determine whether it is greater than or equal to (step 802).

This third predetermined rotation speed N3 is set to a value such that the output of the engine 1 becomes extremely large if the engine rotation speed Ne increases any further.

When the answer to step 802 is affirmative (Yes), that is, when Ne above N3 is established, the opening degree θeX of the control valve 18 is set to the low opening side (step 803), and this subroutine is ended.

FIG. 9 shows an example of a table that is applied to set the opening degree θex of the control valve 18 to the low opening side.
It is set to a fixed value (broken line) lower than X' (solid line).

As is well known, by controlling the opening degree θax of the control valve 18 to the low opening side, the output of the engine l can be reduced, so that the ignition timing O1g is controlled by the subroutine shown in FIG. Similarly, it is possible to improve the toughness of the piston 6, and it is also possible to reliably prevent running out of fuel.

If the answer to the step 801 is affirmative (Yes) or the answer to the step 802 is negative (No), this subroutine is immediately terminated, and the opening degree θ is changed as shown by the solid line in FIG.
Apply ex' as is.

In this embodiment, the engine output is reduced by both retarding the ignition timing and reducing the opening degree of the control brake r, but the present invention is not limited to this and can be implemented in various ways. For example, to control the ignition operation, instead of retarding the ignition timing, the ignition may be stopped or a part of the ignition may be stopped, or only one of the ignition operation and the control valve opening may be controlled. may be applied.

Furthermore, although this embodiment describes a two-stroke engine in which the piston temperature is generally high, it is of course possible to apply the present invention to a four-stroke engine.

(Effects of the Invention) As detailed above, according to the present invention, when the air-fuel ratio of the air-fuel mixture is lean, for example, when the amount of remaining fuel is small, or when the accelerator opening is extremely small, the engine output is maximized. Since the output of the engine can be reduced in the engine rotational speed range above a predetermined rotational speed where

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is an overall side view with a part cut away of a motorcycle, FIG. 2 is a vertical sectional view showing the main parts of the engine, and FIG. An enlarged sectional view along the HI-rll line, Figure 4 is a diagram showing the overall configuration of the engine output control device, and Figure 5 is a diagram showing the remaining fuel amount and engine rotation speed N.
A flowchart of a subroutine for controlling the ignition timing θig according to e, FIG. 6 is a diagram showing a table of ignition timing 01g, and FIG. 7 is a diagram showing the throttle valve opening and engine speed N.
FIG. 8 is a flowchart of a subroutine for controlling the opening degree θex of the control valve r. FIG. 9 is a diagram showing a table of the opening degree θex of the control valve. l... Internal combustion engine, 12... Fuel tank, 14.
2nd thermistor (remaining fuel amount detection means), 18... control valve, 32... central processing unit (CPU) (rotational speed determination means, output reduction means), 36... engine rotational speed (N
e) sensor (rotation speed detection means), 37... ignition device,
39... Throttle valve opening sensor (accelerator opening detection means). Applicant Honda Motor Co., Ltd.

Claims (1)

[Claims] 1. Air-fuel ratio detection means for detecting that the air-fuel ratio of the air-fuel mixture supplied to the engine has become lean; rotation speed detection means for detecting the engine speed; and by the rotation speed detection means. A rotation speed determination means for determining whether the detected engine rotation speed is equal to or higher than a predetermined rotation speed, and an output reduction means for reducing the output of the engine according to the output of the rotation speed determination means and the air-fuel ratio detection means. An output control device for an internal combustion engine, characterized by comprising: 2. The internal combustion engine according to claim 1, wherein the air-fuel ratio detecting means is an accelerator opening detecting means for detecting an accelerator opening of the vehicle or a remaining fuel amount detecting means for detecting the amount of fuel in a fuel tank. output control device.