JPH0968073A - Fuel supply device of two-cycle engine - Google Patents

Abstract

(57) [PROBLEMS] To provide a fuel supply device for a two-cycle engine which can reduce cost, stabilize formation of a uniform mixture, stabilize lean combustion, and improve acceleration. . A main fuel injection valve that functions as a main fuel supply unit that supplies main fuel upstream of a reed valve in an intake passage, and a sub fuel that supplies auxiliary fuel downstream of a scavenging inlet of a scavenging passage. The auxiliary fuel injection valve 30 that functions as a fuel supply unit, the crank angle sensor 9 and the throttle opening sensor 27 that function as an operating state detecting unit that detects the engine operating state from the engine speed and the throttle opening, and the detecting unit. When an acceleration condition is detected,
The control device 18 functions as a sub fuel amount correction unit that increases the fuel amount per cycle supplied from the sub fuel supply unit as the throttle opening increases.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fuel supply system for a two-cycle engine.

[0002]

2. Description of the Related Art A fuel supply system for a two-cycle engine, which is generally used in motorcycles, supplies fuel to an intake passage communicating with a crank chamber, and a mixture of the supplied fuel and air is primarily supplied to the crank chamber. The compressed air-fuel mixture is introduced into the combustion chamber through the scavenging passage.

As described above, in the two-cycle engine, since the intake fuel passage has a long intake path until it reaches the combustion chamber, for example, the air-fuel ratio (A / F) is set to the lean side and steady running is performed. When sudden acceleration occurs, it takes time for the increased fuel to be introduced into the combustion chamber.
The lean air-fuel mixture is introduced for a while, resulting in a problem of poor acceleration response.

As a fuel supply device for solving this problem,
Some fuel supplies fuel directly to the combustion chamber without going through the crank chamber. That is, the fuel injection valve is arranged in the cylinder head or the scavenging passage, and all the necessary amount of fuel is directly injected and supplied into the cylinder.

[0005]

However, in the method of directly supplying all the fuel to the combustion chamber or the scavenging passage like the above-mentioned conventional two-cycle engine, the apparatus becomes expensive, and the time from the fuel supply to the ignition is increased. As a result, the formation of a uniform air-fuel mixture becomes unstable, and combustion especially in a lean air-fuel mixture becomes unstable.

The present invention has been made in view of the above-mentioned problems of the prior art, and can reduce the cost, stabilize the formation of a homogeneous mixture, stabilize the lean combustion, and improve the acceleration. An object of the present invention is to provide a fuel supply device for a two-cycle engine that can be used.

[0007]

According to a first aspect of the present invention, there is provided main fuel supply means for supplying main fuel upstream of a reed valve in an intake passage, and auxiliary fuel for supply downstream of a scavenging inlet of a scavenging passage. Auxiliary fuel supply means, operating state detection means for detecting the engine operating state from the engine speed and throttle opening, and a cycle supplied from the auxiliary fuel supply means when an acceleration state is detected by the detection means. It is characterized in that it is provided with a sub fuel amount correcting means for increasing the fuel amount as the throttle opening becomes larger.

According to a second aspect of the present invention, in the first aspect, the sub fuel amount correction means increases the sub fuel increase amount gradient as the opening speed of the throttle increases.

According to a third aspect of the present invention, in the first or second aspect, the sub fuel amount correction means continues to increase the sub fuel amount by a predetermined number of cycles after the throttle opening is stopped. It has a feature.

According to a fourth aspect of the present invention, in the third aspect, the sub-fuel amount correcting means increases and corrects the sub-fuel amount as the engine speed at the start of the increase of the throttle opening decreases. It is characterized by increasing.

According to a fifth aspect of the present invention, in the third or fourth aspect, the sub fuel amount correction means increases the number of continuous cycles for increasing and correcting the sub fuel amount as the opening speed of the throttle increases. It has a feature.

According to a sixth aspect of the present invention, in any one of the third to fifth aspects, the larger the opening width of the throttle, the larger the number of continuous cycles in which the sub fuel amount is corrected by the sub fuel amount correction means is increased. It is characterized by doing.

According to a seventh aspect of the present invention, in any one of the third to sixth aspects, the auxiliary fuel amount correcting means increases the number of continuous cycles for increasing and correcting the auxiliary fuel amount as the throttle opening degree increases. It is characterized by that.

According to an eighth aspect of the present invention, in any one of the third to seventh aspects, the sub-fuel amount correcting means increases the number of continuous cycles for increasing and correcting the sub-fuel amount as the transmission has a lower speed stage. It is characterized by doing.

According to a ninth aspect of the present invention, in any one of the third to eighth aspects, the sub-fuel amount correction means maximizes the sub-fuel increase amount for each cycle when the throttle opening is stopped and is gradually increased. It is characterized by reducing to.

According to a tenth aspect of the present invention, in any one of the third to ninth aspects, when the auxiliary fuel amount correction means changes the throttle opening to the closing side while the increased auxiliary fuel is being supplied, The feature is that the supply of increased secondary fuel is stopped.

According to an eleventh aspect of the present invention, in any one of the third to ninth aspects, the sub fuel amount correction means is configured such that the throttle opening is further opened than the increase stop opening during the supply of the increased sub fuel. When changed to the side, the supply control of the increased auxiliary fuel based on the opening degree at the time of the increase stop is stopped, and the supply control of the increased auxiliary fuel based on the new opening degree is performed.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 to 12 are views for explaining a fuel supply device for a two-cycle engine according to an embodiment of the present invention, FIG. 1 is an overall configuration diagram of the fuel supply device of the present embodiment, and FIGS. Flowchart diagrams for explaining the operation, and FIGS. 5 to 12 are characteristic diagrams for explaining the control operation.

In the drawing, reference numeral 1 is a spark ignition type two-cycle engine, and this engine 1 is composed of an upper and lower half split type crankcase 2, a cylinder block 3 and a cylinder head 4.

Cylinder bore 3 of the cylinder block 3
A piston 5 is slidably arranged in a, and the piston 5 is connected via a connecting rod 6 to a crank shaft 7 arranged in a crank chamber 2a. A crank angle sensor 9 that also functions as an engine speed sensor for measuring the rotation angle of the crank shaft 7 and the engine speed is attached to the crankcase 2, and a detection signal from the sensor 9 is a control device ( It is input to the ECU) 18.

The cylinder head 4 and the piston 5 are also provided.
A combustion chamber 10 is formed between them and an ignition plug 26 is screwed into the combustion chamber 10. Reference numeral 12 is a cooling water jacket formed at appropriate positions on the cylinder head 4 and the cylinder block 3, 11 is a combustion chamber pressure detection sensor, and 25 is a combustion chamber temperature detection sensor. It is input to the control unit (ECU) 18. The output of the crankshaft 7 is a clutch device (not shown),
It is transmitted to the wheels via the transmission and chain device. A shift stage detection sensor is arranged in the transmission, and a shift stage detection signal is similarly input to the ECU 18.

In the exhaust passage 13 of the cylinder block 3, an exhaust adjusting valve 40 for changing the exhaust timing is arranged, and the exhaust adjusting valve 40 is provided in the control unit (ECU) 1.
The rotation angle position is controlled by the exhaust control signal from 8. Reference numeral 33 is an oxygen concentration sensor that detects the oxygen concentration in the combustion gas that does not include blow-through gas. An intake passage 14 is connected to the intake port 2b opening in the crank chamber 2a with a reed valve 15 interposed therebetween.
A throttle body having a throttle valve 21a is connected to the intake passage 14. A throttle opening sensor 27 is provided on the rotary shaft of the throttle valve 21a,
The throttle opening sensor 27 is connected to the control device 18. An intake air temperature sensor 19 is provided upstream of the throttle valve 21a of the throttle body 21, and a main fuel injection valve 28 is provided downstream thereof. The fuel injection timing and injection amount of the main fuel injection valve 28 are controlled by the main fuel injection signal from the control device 18.

A scavenging passage 29 is formed in the cylinder block 3, and the passage 29 communicates the inside of the crank chamber 2a with a portion of the cylinder bore 3a facing the exhaust passage 13. Then, the scavenging passage 2
The cylinder bore 3a is located downstream of the scavenging inlet 29a of the cylinder 9.
A sub-fuel injection valve 30 for injecting a sub-fuel toward the inside is attached, and the amount of fuel from the sub-fuel injection valve 30 is controlled by the control device 18 by a method described later.

Next, the engine 1 by the control device 18 will be described.
Will be described. This control includes the processing of the main routine for controlling various operating states of the engine 1 shown in FIGS. 2 and 3, the ignition timing shown in FIG. 4 performed for each cycle of the engine 1, that is, for each crankshaft revolution, and It is composed of an interrupt routine process for controlling fuel injection.

In the control of the above-mentioned main routine, first, ON / OFF of a main switch (ignition key) not shown is detected, and if it is OFF, this control is stopped (steps S1 and S2).

If the switch is not turned off, the detection signal of the operating state by each sensor is read and stored in the memory (step S3). Specifically, the engine speed, throttle opening, intake air amount, shift speed, oxygen concentration, etc. are read as operating state detection signals.

The transient state is quantitatively calculated based on the detected operating state and the operating state at the preceding time stored in the memory of the control device 18, and the read operating state is also calculated. Based on the ignition timing,
Basic values of the control amount such as the fuel injection amount, the injection timing, the exhaust timing (timing) are calculated (steps S4 and S5).

A correction value is calculated based on the calculated basic values of intake air temperature, transient state, exhaust pipe wall temperature, oxygen concentration, catalyst temperature, etc. (step S6).

Then, a control amount such as an ignition timing, a fuel injection amount, an injection timing, an exhaust timing, etc. is calculated from the calculated basic value and the correction value (step S7), and based on the control amount, the main amount is controlled. The injection end timing of the sub fuel injection valves 28 and 30 is calculated (step S8).

Here, for example, when no abnormality such as engine over-rotation, overheat, knocking, oil shortage, etc. is detected, the above calculation result is stored in the memory in the controller 18 (steps S9, S10), and the abnormality is also detected. When is detected, each control amount is calculated based on the abnormal control amount map (step S11), and the calculation result is stored.

After the exhaust timing variable valve 40 and the like are controlled on the basis of the stored calculation result,
The process moves to step S1 and the process of the main routine is repeated.

On the other hand, in the interrupt routine, first, the crank angle from the crank angle sensor 9 is read as a reference value for this processing, and the control amount data of a predetermined operating region is read from the memory in the control device 18. Is read (steps S13 and S14).

Next, the spark plug 26 is ignited at a timing according to the read ignition timing data, and at the timing according to the read fuel injection amount data, the main fuel injection valve 28 and the sub fuel Main fuel and sub fuel are injected from the injection valve 30, respectively, and
It is stopped at a predetermined timing, that is, the crankshaft 1
The main fuel is injected during the intake stroke of each rotation (every combustion cycle), and the sub fuel is injected during the scavenging stroke (steps S15 to S1).
9), and the processing shifts to step S13.

Here, the control of the sub fuel amount by the sub fuel injection valve 30 will be described in detail. This is performed based on the map data shown in FIGS. 5 to 11 stored in the control device 18.

FIG. 5 shows the relationship between the throttle opening and the throttle opening speed and the amount of auxiliary fuel per cycle. As is clear from FIG. 5, this auxiliary fuel amount increases as the throttle opening increases. Will be increased. This will be described with reference to FIG. 6. When the throttle opening degree increases from the angle θ ₁ to θ ₂ , the auxiliary fuel amount is such that the supply amount (q) per engine cycle increases in accordance with the increase of the opening degree. Increased from q ₁ to q ₂ .

As shown in FIG. 5, the auxiliary fuel supply amount (increased correction amount q) is such that the throttle opening is θ.
_The speed is controlled to increase as the speed (throttle opening speed) changing from ₁ to θ ₂ increases. Therefore, as the throttle 21 is operated in a shorter time, for example, at the time of sudden acceleration, the increase correction amount of the sub fuel is increased, and the acceleration response of the engine 1 is improved accordingly.

When the throttle opening is kept constant at θ ₂ , the supply of the auxiliary fuel is not immediately stopped for a time (T _{1 to} T ₂ ) corresponding to a predetermined number of engine cycles. It is continued and the supply amount (q) of the auxiliary fuel is gradually reduced from q ₂ to q ₁ at a predetermined rate. In this reduction of the auxiliary fuel, it is desirable that the amount is reduced by a constant amount for each cycle as shown by the characteristic line B in FIG. Note that, as shown by characteristic lines C and D in FIG. 12, the reduction amount may be changed between the first half and the second half of the start of reduction of the auxiliary fuel.

Here, it is suitable that the number of engine cycles for continuing the supply of the sub fuel is 50 to 250 cycles. Specifically, it is set to the sum of the numbers of sub fuel supply cycles b1 to b5 shown in FIGS.

The number of sub fuel supply cycles b1 to b5 is
The opening of the throttle valve 21a is θ ₁Engine times at
The lower the number of turns, the more it increases (see Fig. 7).
The operation angle per unit time, which is the operation speed of 21a (dθ /
dt) increases as it increases (see FIG. 8), and
Of the throttle valve 21a, that is, the difference in throttle opening.
(Θ₂−θ₁) Is larger (see FIG. 9), the above
The opening degree (θ₂) Is large
It increases (see FIG. 10), and the transmission of the engine 1 is changed.
The lower the number of gears (shifts) in the gear, the lower the gears
Control (see FIG. 11). In addition, the above sub fuel
The number of continuous supply cycles is one of the above b1 to b5.
May be set to multiple sums.

As described above, the larger the opening degree and the opening speed of the throttle valve 21a, the more the supply amount of the auxiliary fuel per engine cycle is increased. Therefore, it is possible to prevent the fuel supply to the combustion chamber 10 from being delayed during acceleration. As shown in FIG.
The engine speed can be increased without delaying the operation of the throttle, and the acceleration performance of the engine 1 can be improved.

Further, after the operation of the throttle valve 21a is stopped, the increase correction of the auxiliary fuel amount is continued for a predetermined number of cycles and the increase amount is gradually decreased. The main fuel that is supplied to the sub fuel is smoothly and continuously supplied into the cylinder, and the rotational response of the engine 1 during acceleration is improved. That is, as shown in FIG. 6, as the main fuel increases, the sub fuel decreases, and the total amount thereof becomes an amount according to the throttle opening, and therefore the response of the engine speed to the throttle opening becomes good. .

Here, during acceleration, the throttle valve 21a
If is closed, the supply of auxiliary fuel is immediately stopped. This is the invention of claim 10 and, thereby, the response at the time of deceleration becomes good.

Further, when the throttle 21 is opened further than when the opening operation is stopped, the supply control of the sub fuel based on the throttle opening when the operation is stopped is stopped, and the sub fuel based on the new opening is stopped. Supply control. This is the invention of claim 11, and thereby, the response at the time of reacceleration can be improved.

The present invention is also applicable to a multi-cylinder engine. That is, a plurality of cylinder bores 3a, a crank chamber 2a, an exhaust passage 13, an intake port 2 are provided in a common crankcase 2, cylinder block 3 and cylinder head 4.
a and the scavenging passage 29 are formed independently of each other, and the explosive combustion in the combustion chamber 10 for each cylinder is transmitted as a rotational force to the common crankshaft 7 by each piston 5 and connecting rod 6.

Main fuel injection valve 28 arranged for each cylinder
The fuel supply from the auxiliary fuel injection valve 30 and the fuel injection valve 30 are performed for each cycle in accordance with the intake stroke and the scavenging stroke of each cylinder.

In an engine of the type in which fuel is supplied from the main fuel injection valves 28 of all cylinders in the entire engine operating range, the supply of sub fuel from the sub fuel injection valves 30 of all cylinders is performed in the same manner as above. It

On the other hand, in the case of performing the cylinder deactivation operation in which the number of cylinders that inject fuel from the main fuel injection valve 28 is reduced in the low load region where the throttle opening is small, the throttle opening after the increase of the throttle opening is still cylinder deactivated. When in the operating range, the auxiliary fuel injection valve 30 for increasing the injection amount is limited to the cylinder in which the main fuel injection valve 28 is operating. Further, when the throttle opening after the increase of the throttle opening is in the all-cylinder operating range, the main fuel injection valve 28 of the cylinder that has been the deactivated cylinder in the cylinder deactivating operating range is also used to increase the injection amount of the cylinder. Is made larger than the increased injection amount of the cylinder which was not so. As a result, acceleration can be further improved.

[0048]

As described above, in the fuel supply system for a two-cycle engine according to the invention of claim 1, the auxiliary fuel is supplied to the downstream side of the scavenging inlet of the scavenging passage, and the larger the throttle opening, the more Since the supply amount of the sub fuel is increased, the fuel can be immediately supplied to the cylinder without passing through the crankcase even when the fuel is accelerated during lean combustion, so that the acceleration response of the engine can be improved.

In the fuel supply system for a two-cycle engine according to the second aspect of the present invention, the increasing gradient of the auxiliary fuel is increased as the opening speed of the throttle is increased. Therefore, more auxiliary fuel is supplied during the rapid acceleration. Therefore, there is an effect that the acceleration response of the engine can be further improved.

In the fuel supply system for a two-cycle engine according to the third aspect of the present invention, after the throttle opening is stopped increasing, the auxiliary fuel amount increase correction is continued for a predetermined number of cycles. It is possible to continuously supply the auxiliary fuel until the supplied main fuel reaches the cylinder, and the total amount of the main fuel and the auxiliary fuel in the cylinder can be set to an amount according to the acceleration state. There is an effect that the responsiveness can be improved.

In setting the number of cycles for continuing the correction for increasing the auxiliary fuel, the lower the engine speed at the start of increasing the throttle opening, the more the opening speed of the throttle in the invention of claim 5 is set. Is larger, the opening width of the throttle is larger in the invention of claim 6, and the throttle opening is larger in the invention of claim 7,
In the invention described above, the number of cycles for increasing and correcting the sub fuel amount is increased as the transmission has a lower speed.
It is realized that the sum of the main fuel and the sub fuel in the cylinder is set to an amount according to the acceleration state.

In the fuel supply system for a two-cycle engine according to the ninth aspect of the present invention, the auxiliary fuel increase amount for each cycle is maximized when the throttle opening is stopped and gradually decreased. There is an effect that the total of the fuel and the sub fuel can be more smoothly corresponded to the acceleration state.

In the fuel supply system for a two-cycle engine according to the tenth aspect of the present invention, when the throttle opening changes to the closing side during the supply of the increased auxiliary fuel, the supply of the increased auxiliary fuel is stopped. According to the invention of claim 11, 2
In the fuel supply device of the cycle engine, when the throttle opening changes further to the open side from the opening of the increasing stop during the supply of the increasing auxiliary fuel, the supply control based on the opening degree of the increasing stop of the increasing auxiliary fuel is stopped, Since the supply control of the increased secondary fuel is performed based on the new opening degree, there is an effect that the responsiveness during deceleration or reacceleration can be improved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a fuel supply system for a two-cycle engine according to an embodiment of the present invention.

FIG. 2 is a flow chart for explaining a control operation of the fuel supply device.

FIG. 3 is a flow chart diagram for explaining a control operation of the fuel supply device.

FIG. 4 is a flow chart diagram for explaining a control operation of the fuel supply device.

FIG. 5 is a characteristic diagram for explaining a control operation of the fuel supply device.

FIG. 6 is a characteristic diagram for explaining a control operation of the fuel supply device.

FIG. 7 is a characteristic diagram for explaining a control operation of the fuel supply device.

FIG. 8 is a characteristic diagram for explaining a control operation of the fuel supply device.

FIG. 9 is a characteristic diagram for explaining a control operation of the fuel supply device.

FIG. 10 is a characteristic diagram for explaining a control operation of the fuel supply device.

FIG. 11 is a characteristic diagram for explaining a control operation of the fuel supply device.

FIG. 12 is a characteristic diagram for explaining a control operation of the fuel supply device.

[Explanation of symbols]

 9 Crank angle sensor (operating state detecting means) 14 Intake passage 15 Reed valve 18 Control device (sub fuel amount correcting means) 27 Throttle opening sensor (operating state detecting means) 28 Main fuel injection valve (main fuel supply means) 29 Scavenging Passage 30 Sub fuel injection valve (sub fuel supply means)

Claims (11)

[Claims] 1. A main fuel supply means for supplying main fuel upstream of a reed valve of an intake passage, a sub fuel supply means for supplying sub fuel downstream of a scavenging inlet of a scavenging passage, an engine speed and a throttle. When the operating state detecting means for detecting the engine operating state from the opening degree and the accelerating state are detected by the detecting means, the fuel amount per cycle supplied from the sub fuel supply means is increased as the throttle opening degree increases. A fuel supply device for a two-cycle engine, comprising: an increasing auxiliary fuel amount correcting means. 2. The fuel supply system for a two-cycle engine according to claim 1, wherein the auxiliary fuel amount correction means increases the auxiliary fuel increase amount gradient as the opening speed of the throttle increases. 3. The two-cycle system according to claim 1, wherein the sub-fuel amount correction means continues the sub-fuel amount increase correction for a predetermined number of cycles after the throttle opening is stopped increasing. Engine fuel supply system. 4. The sub-fuel amount correcting means according to claim 3, wherein the sub-fuel amount correction means increases the number of continuous cycles for increasing and correcting the sub-fuel amount as the engine speed at the start of increasing the throttle opening is lower. Characteristic two-cycle engine fuel supply device. 5. The two cycles according to claim 3 or 4, wherein the auxiliary fuel amount correcting means increases the number of continuous cycles for increasing and correcting the auxiliary fuel amount as the opening speed of the throttle increases. Engine fuel supply system. 6. The method according to claim 3, wherein the auxiliary fuel amount correction means increases the number of continuous cycles for increasing and correcting the auxiliary fuel amount as the opening width of the throttle increases. Fuel supply system for 2-cycle engine. 7. The auxiliary fuel amount correction means according to claim 3, wherein the auxiliary fuel amount correction means increases the number of continuous cycles for increasing and correcting the auxiliary fuel amount as the throttle opening degree increases. Fuel supply system for 2-cycle engine. 8. The auxiliary fuel amount correction means according to claim 3, wherein the lower the speed of the transmission,
A fuel supply system for a two-cycle engine, characterized in that the number of continuous cycles for increasing and correcting the sub fuel amount is increased. 9. The auxiliary fuel amount correction means according to claim 3, wherein the auxiliary fuel amount correction means maximizes the auxiliary fuel increase amount for each cycle when the throttle opening is stopped and stops gradually. Characteristic two-cycle engine fuel supply device. 10. The method according to claim 3, wherein
The fuel supply device for a two-cycle engine, wherein the auxiliary fuel amount correction means stops the supply of the increased auxiliary fuel when the throttle opening changes to the closing side during the supply of the increased auxiliary fuel. . 11. The method according to any one of claims 3 to 9,
When the throttle opening degree changes to the open side from the opening degree of the increasing stop during the supply of the increasing auxiliary fuel, the auxiliary fuel amount correcting means is based on the increasing stop opening degree of the increasing auxiliary fuel. A fuel supply device for a two-cycle engine, characterized in that the supply control is stopped and the supply control of the increased auxiliary fuel is performed based on a new opening degree.