TW202342868A - Independent-throttle-type four-stroke engine - Google Patents

Abstract

Provided is a four-stroke engine wherein, in at least part of a low-load operation period in which the signal of an intake pressure detector varies greatly in one combustion cycle, a control device acquires a required fuel amount or estimates an air amount to be taken into a combustion chamber in the next combustion cycle after the combustion cycle, on the basis of a compression stroke intake pressure acquired during a compression stroke when the intake pressure is trending upward and a compression stroke throttle valve position detected in said compression stroke, and also on the basis of a subsequent throttle valve position acquired at the time of an intake pressure higher than the intake pressure at the time the compression stroke throttle valve position was detected, which is a time after the time at which the compression stroke throttle valve position was acquired in the same combustion cycle as the compression stroke, and the control device controls a fuel supply device to supply fuel prior to the next combustion.

Description

Independent throttle four-stroke engine

The invention relates to an independent throttle four-stroke engine.

An independent throttle four-stroke engine is a four-stroke engine with the following components: at least one combustion chamber; an air intake passage, which is separately provided in each combustion chamber; a throttle valve, which is set inside the intake passage to adjust The amount of air sucked into the combustion chamber; and a fuel supply device that supplies fuel to the combustion chamber.

In a four-stroke engine that repeats the combustion cycle starting from the intake stroke and ending after the compression stroke, expansion stroke and exhaust stroke, the amount of air sucked into the combustion chamber in the next combustion cycle is estimated, and the amount of air sucked into the combustion chamber in the next combustion cycle is supplied to the combustion chamber and the estimated result is obtained. The corresponding amount of fuel is controlled in a manner. In the case of an independently throttled four-stroke engine, the intake volume downstream of the throttle will become smaller, so changes in air volume can respond quickly to changes in operating conditions. Therefore, it is desired to estimate with high accuracy the amount of air sucked into the combustion chamber or the amount of fuel required in the next combustion cycle.

For example, Patent Document 1 describes that when the engine rotation speed is low, the air amount is estimated based on the intake air pressure and the engine rotation speed, and when the engine rotation speed is high, the air amount is estimated based on the opening of the throttle valve. degree and the rotational speed of the engine to estimate the amount of air in the next combustion cycle. Furthermore, Patent Document 2 describes that the air amount in the next combustion cycle is estimated using the intake air pressure detected during the compression stroke and the intake air pressure detected during the expansion stroke. [Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2002-317668 [Patent Document 2] Japanese Patent Application Publication No. 2008-157219

[Problem to be solved by the invention]

In the technology described in Patent Document 1, various correction coefficients need to be set according to the operating conditions and debugged to achieve the target value. How to set the correction coefficient depends on the skill of the setter. In the technology described in Patent Document 2, it is necessary to improve the accuracy of the map that matches the detected intake air pressure with the air amount and the coefficients of various calculation formulas, so the number of steps for system construction increases.

The present invention was completed in view of the above problems, and its object is to provide an independently throttled four-stroke engine that can improve the estimation accuracy of the amount of air sucked into the combustion chamber or the amount of required fuel, and can also reduce the dependence on manual skills. degree, thereby reducing the number of steps in system construction. [Technical means to solve problems]

The independently throttled four-stroke engine of the present invention is provided with: at least one combustion chamber; an independent air intake passage, one end of which is connected to one of the above-mentioned combustion chambers, and the other end is not connected to the above-mentioned combustion chamber; an independent throttle valve, which is provided on the above-mentioned independent The inside of the intake passage adjusts the amount of air sucked into the combustion chamber; a throttle valve position detector detects the position of the independent throttle valve; an intake pressure detector detects the independent throttle position of the independent intake passage. The intake air pressure between the flow valve and the above-mentioned combustion chamber; a fuel supply device that supplies fuel to the above-mentioned combustion chamber; and a control device that controls the above-mentioned fuel based on the signals from the above-mentioned throttle valve position detector and the above-mentioned intake air pressure detector. supply device; and when the four strokes starting from the intake stroke defined by the piston position and ending with the compression stroke, expansion stroke and exhaust stroke are defined as one combustion cycle, the above control device operates in one combustion cycle At least part of the low-load operation period in which the signal of the above-mentioned intake pressure detector fluctuates significantly, based on the compression stroke intake pressure obtained during the compression stroke in which the intake air pressure shows a rising tone, and the compression stroke detected during the compression stroke. Throttle valve position, and a point later than the time point when the above-mentioned compression stroke throttle valve position is obtained in the same combustion cycle as the above-mentioned compression stroke, and the intake air pressure is higher than the intake air pressure at the time point when the above-mentioned compression stroke throttle valve position is detected The subsequent throttle position obtained at the highest time point is used to estimate the amount of air sucked into the combustion chamber in the next above-mentioned combustion cycle, or to obtain the required fuel amount, and control the above-mentioned fuel supply device to supply it before the next combustion. fuel.

According to this configuration, the intake air pressure of the compression stroke that has a higher correlation with the air amount among the fluctuating intake air pressures, the compression stroke throttle valve position detected in the same stroke of the compression stroke, and the position of the compression stroke are used. The time point at which the throttle valve position is detected is closer to the subsequent throttle valve position at the next combustion time, and the amount of air sucked into the combustion chamber in the next combustion cycle can be estimated, or the required fuel amount can be obtained, thereby both It improves the estimation accuracy of the amount of air sucked into the combustion chamber or the amount of fuel required under transition and steady states, and reduces the dependence on manual skills, thus reducing the number of steps in system construction.

In the independently throttled four-stroke engine of the present invention, the compression stroke throttle position and the subsequent throttle position are detection values obtained by the throttle position detector.

According to this configuration, control is performed to estimate the air amount or obtain the required fuel amount using the detection value obtained by the throttle position detector. Therefore, for example, it is different from the case where a predicted value based on the opening and closing speed of the throttle valve is used. ratio, it can improve the estimation accuracy of air volume or required fuel volume. [Effects of the invention]

According to the present invention, an independent throttle type four-stroke engine can be provided, which can not only improve the estimation accuracy of the air amount or the required fuel amount during the transition, but also reduce the dependence on manual skills, thereby reducing the number of steps in system construction. .

Hereinafter, the embodiment of the four-stroke engine will be described based on the drawings. In addition, this invention is not limited by this embodiment. In addition, the components in the following embodiments include those that can and are easily replaced by manufacturers, or those that are substantially the same.

FIG. 1 is a diagram schematically showing an example of a four-stroke engine 100. The four-stroke engine 100 of this embodiment is an independent throttle engine. The four-stroke engine 100 includes an engine body 10, an independent intake passage 21 and an exhaust passage 22, an intake valve 31 and an exhaust valve 32, an independent throttle valve 33, a crankshaft angle detector 41, a throttle position detector 42, Intake air pressure detector 43, fuel injection device 50 and control device 60.

The engine body 10 has a cylinder 11 and a crankcase 12 . At least one cylinder 11 is provided. The number of cylinders 11 is not particularly limited, and can be single cylinder, double cylinder, three cylinder, four cylinder, etc. Cylinder 11 has a combustion chamber 13 . The combustion chamber 13 has an intake opening 17 and an exhaust opening 18 . Furthermore, a spark plug 19 is arranged in the combustion chamber 13 . The spark plug 19 ignites the mixed gas supplied to the inside of the combustion chamber 13, whereby the mixed gas burns.

A piston 14 is arranged in the combustion chamber 13 . The piston 14 reciprocates in the cylinder 11 by burning the mixed gas containing the fuel supplied to the combustion chamber 13 . By the reciprocating movement of the piston 14, the volume of the combustion chamber 13 increases or decreases. The piston 14 is connected to the crankshaft 16 via a connecting rod 15 . The crankshaft 16 rotates in conjunction with the reciprocating movement of the piston 14 . The crankshaft 16 is arranged in the crankcase 12 .

The independent air intake passage 21 is connected to the air intake opening 17 of the combustion chamber 13 . The air intake opening 17 is a connection between the combustion chamber 13 and the independent air intake passage 21 . The independent air intake passage 21 has an atmosphere opening 21a which is an opening facing the atmosphere.

The exhaust passage 22 is connected to the exhaust opening 18 of the combustion chamber 13 . The exhaust opening 18 is a connection portion between the combustion chamber 13 and the exhaust passage 22 .

The intake valve 31 opens and closes the intake opening 17 . The exhaust valve 32 opens and closes the exhaust opening 18 . The intake valve 31 and the exhaust valve 32 are driven by a driving mechanism 34 such as a camshaft, thereby performing opening and closing operations.

The independent throttle valve 33 is arranged inside the independent air intake passage 21 . The independent throttle valve 33 adjusts the amount of air sucked into the combustion chamber 13 . The independent throttle valve 33 may be disposed at a position where the distance L1 between the intake valve 31 and the independent throttle valve 33 is shorter than the distance L2 between the independent throttle valve 33 and the atmospheric opening 21 a of the independent air intake passage 21 . Furthermore, the independent throttle valve 33 may be disposed at a position where the volume V1 of the independent intake passage 21 downstream of the independent throttle valve 33 is smaller than the stroke volume V2 of the cylinder 11 . When the independent throttle valve 33 is disposed close to the intake valve 31 in this way, the responsiveness of the amount of air sucked into the combustion chamber 13 is improved.

The crankshaft angle detector 41 detects the rotation angle of the crankshaft 16, that is, the crankshaft rotation angle.

The throttle position detector 42 detects the position of the independent throttle valve 33, that is, the throttle position.

The intake pressure detector 43 detects the intake pressure between the independent throttle valve 33 in the independent intake passage 21 and the combustion chamber 13 .

As the detector, in addition to the above-mentioned detectors, for example, a detector that detects the temperature inside the independent air intake passage 21 , a detector that detects the temperature inside the engine body 10 , a detector that detects the number of engine revolutions, etc. (not shown) may be provided. Various detectors are shown.

The fuel injection device 50 injects fuel into the independent air intake passage 21 . The fuel injection device 50 supplies fuel into the inside of the independent air intake passage 21 by injecting fuel.

The control device 60 has a processing device such as a CPU (Central Processing Unit), a memory device such as a RAM (Random Access Memory) or a ROM (Read Only Memory), a timer, and the like. The control device 60 receives detection results from each detector such as the crankshaft angle detector 41, the throttle position detector 42, and the intake air pressure detector 43.

The control device 60 controls the fuel injection device 50 and the spark plug 19 . The control device 60 controls the amount of fuel injected by the fuel injection device 50 and the timing of fuel injection. The control device 60 controls the ignition sequence of the spark plug 19 .

The four-stroke engine 100 configured as above repeats the combustion cycle. A combustion cycle consists of four strokes starting from the compression stroke defined by the piston position and ending with the expansion stroke, exhaust stroke and intake stroke. Before the intake stroke, fuel is injected into the inside of the independent intake passage 21 from the fuel injection device 50 . In the intake stroke, the intake valve 31 is opened, whereby a mixture of air passing through the independent throttle valve 33 and fuel injected from the fuel injection device 50 is supplied to the combustion chamber 13 of the cylinder 11 . During the compression stroke, the piston 14 compresses the mixed gas in the combustion chamber 13 . During the expansion stroke, the mixed gas ignited by the spark plug 19 burns and pushes the piston 14 at the same time. During the exhaust stroke, the exhaust valve 32 is opened, whereby the burned exhaust gas is discharged from the combustion chamber 13 to the exhaust passage 22 .

The control in the control device 60 will be described with reference to FIG. 2 . FIG. 2 is a diagram showing an example of the relationship between the detection value of the intake air pressure detected by the intake air pressure detector 43, the value of the intake air pressure used for control, the throttle valve position, and time. The vertical axis of Figure 2 represents relative values, and the horizontal axis represents time. In Figure 2, the horizontal axis can also be the crankshaft angle.

As shown in FIG. 2 , the detection value D1 of the intake pressure detected by the intake pressure detector 43 increases as it advances from the compression stroke to the exhaust stroke, and decreases in the intake stroke of the next combustion cycle. . The control device 60 uses, for example, a value (control value) D2 based on a detection value detected by the intake pressure detector 43 at a specific timing for each compression stroke in a continuous combustion cycle as the intake air pressure. In FIG. 2 , the throttle position D3 is a value when the opening of the independent throttle valve 33 becomes larger.

The control device 60 obtains the signal from the intake pressure detector 43 , that is, the detected value of the intake pressure, at least part of the low-load operation period in which the intake pressure fluctuates significantly in one combustion cycle at the first point in the compression stroke when the intake pressure shows a rising tone. The intake pressure of the compression stroke and the throttle valve position of the compression stroke detected by t1. Here, the compression stroke in which the intake air pressure rises refers to the period when air is sucked into the cylinder 11 from the independent intake passage 21 and the independent intake passage 21 becomes negative pressure. Starting around the closing period of 31, air flows from the independent throttle valve 33 into the independent air intake passage 21, and the pressure gradually recovers. The intake pressure during the compression stroke is the detection value of the intake pressure obtained by the intake pressure detector 43 at the first time point t1. The compression stroke throttle position is the throttle position obtained by the throttle position detector 42 in the same compression stroke as the first time point t1.

The control device 60 obtains the subsequent throttle position detected at the second time point t2 which is later than the first time point t1 in the same combustion cycle as the compression stroke and where the intake pressure is higher than the intake pressure at the first time point t1 . The subsequent throttle position is the throttle position obtained by the throttle position detector 42 at the second time point t2. In this embodiment, the second time point t2 is, for example, a time point within the expansion stroke of the same combustion cycle as the compression stroke. However, it is not limited to this. For example, it may also be a time point within the compression stroke, or it may be the same as the compression stroke. The time point within the exhaust stroke of the combustion cycle where the compression stroke is the same.

The control device 60 estimates the amount of air sucked into the combustion chamber in the next combustion cycle based on the compression stroke intake pressure and compression stroke throttle position obtained in one combustion cycle, and the subsequent throttle valve position, or Get the required amount of fuel. For example, the control device 60 may estimate the amount of air sucked into the combustion chamber in the next combustion cycle based on the compression stroke intake pressure, the compression stroke throttle position, and the subsequent throttle position, such as based on a specific air amount map. In addition, the control device 60 can obtain the required fuel amount in the next combustion cycle based on the compression stroke intake pressure, the compression stroke throttle position, and subsequent throttle valve positions, for example, according to a specific calculation formula. In addition, the control device 60 can estimate the atmospheric pressure based on the compression stroke intake pressure, the compression stroke throttle valve position, and subsequent throttle valve positions, and obtain the required fuel amount in the next combustion cycle based on the estimated atmospheric pressure. As a timing sequence for estimating the atmospheric pressure, a stable situation such as a steady state situation in which the position of the independent throttle valve 33 does not shift can be cited, for example.

The control device 60 performs control to estimate the air amount or obtain the above-mentioned required fuel amount without using intake air pressure other than the compression stroke.

Based on the estimated air amount or the obtained required fuel amount, the control device 60 controls the fuel injection device 50 to supply fuel before combustion in the next combustion cycle.

The control device 60 continuously causes a fixed and small change in the opening of the independent throttle valve 33 in a steady-state situation in which the position of the independent throttle valve 33 does not shift, and during low-load operation in which the throttle valve opening is small. In a slow acceleration situation where the rate slowly increases, control is performed by injecting J1 when the intake valve is closed. Intake valve closing injection J1 refers to the injection of fuel from the fuel injection device 50 during the valve closing period T1 when the intake valve 31 is closed after the compression stroke in one combustion cycle.

In an acceleration situation in which the position of the independent throttle valve 33 shifts to a larger open valve state, the control device 60 can perform injection J1 when the intake valve is closed and injection J2 when the intake valve is open. The intake valve opening injection J2 refers to the injection of fuel from the fuel injection device 50 during the valve opening period T2 when the intake valve 31 is opened after the valve closing period T1 within one combustion cycle. Furthermore, the acceleration scenario in which the position of the independent throttle valve 33 shifts to a larger valve opening state includes, for example, the acceleration scenario in which the position of the independent throttle valve 33 shifts from a low-load operation period to a high-load operation period. The low-load operation period may be, for example, a state in which the load torque is lower than the average value of the load torque within one combustion cycle. In addition, during the high load operation period, the load torque may be higher than the average value of the load torque within one combustion cycle. In such an acceleration situation, the control device 60 can perform control by injecting J1 when the intake valve is closed and injecting J2 when the intake valve is open, or by injecting J1 when the intake valve is closed but not opening the intake valve. The valve is controlled by injecting J2.

FIG. 3 is a diagram showing another example of the relationship between the detection value of the intake air pressure detected by the intake air pressure detector 43, the value of the intake air pressure used for control, the throttle valve position, and time. The vertical axis of Figure 3 represents relative values, and the horizontal axis represents time. In Figure 3, the horizontal axis can also be the crankshaft angle.

As shown in FIG. 3 , the detection value D1 of the intake pressure detected by the intake pressure detector 43 increases as it advances from the compression stroke to the exhaust stroke, and decreases in the intake stroke of the next combustion cycle. . The control device 60 uses, for example, a value (control value) D2 based on a detection value detected by the intake pressure detector 43 at a specific timing for each compression stroke in a continuous combustion cycle as the intake air pressure. In the example shown in FIG. 3 , the throttle position D3 is a value in which the opening degree of the independent throttle valve 33 becomes smaller.

The control device 60 obtains the signal from the intake pressure detector 43 , that is, the detected value of the intake pressure, at least part of the low-load operation period in which the intake pressure fluctuates significantly in one combustion cycle at the third time point of the compression stroke when the intake pressure shows a rising tone. The compression stroke intake pressure and compression stroke throttle valve position detected by t3. The intake pressure of the compression stroke is the detection value of the intake pressure obtained by the intake pressure detector 43 at the third time point t3. The compression stroke throttle position is the throttle position obtained by the throttle position detector 42 in the same compression stroke as the third time point t3.

The control device 60 obtains the subsequent throttle position detected at the fourth time point t4 which is later than the third time point t3 in the same combustion cycle as the compression stroke and where the intake pressure is higher than the intake pressure at the third time point t3. The subsequent throttle position is the throttle position obtained by the throttle position detector 42 at the fourth time point t4. In this embodiment, the fourth time point t4 is, for example, a time point within the expansion stroke of the combustion cycle that is the same as the compression stroke. However, it is not limited to this. For example, it may also be a time point within the compression stroke, or it may be the same as the compression stroke. The time point within the exhaust stroke of the combustion cycle where the compression stroke is the same.

As in the case shown in FIG. 2 , the control device 60 estimates the next combustion in the combustion cycle based on the compression stroke intake pressure and the compression stroke throttle valve position obtained in one combustion cycle, as well as the subsequent throttle valve position. The amount of air sucked into the combustion chamber during the cycle, or the required amount of fuel.

The control device 60 performs control to estimate the air amount or obtain the above-mentioned required fuel amount without using intake air pressure other than the compression stroke.

Based on the estimated air amount or the obtained required fuel amount, the control device 60 controls the fuel injection device 50 to supply fuel before combustion in the next combustion cycle.

FIG. 4 is a flowchart showing an example of control in the control device 60 of the four-stroke engine 100. As shown in FIG. 4 , the control device 60 obtains the signal from the intake pressure detector 43 , that is, the detected value of the intake pressure, during at least part of the low-load operation period in which the intake pressure is rising in one combustion cycle. The intake air pressure of the compression stroke detected at the first time point t1 of the compression stroke (see FIG. 2 ), and the throttle valve position detected during the compression stroke (step S10 ). In step S10, either the acquisition of the compression stroke intake pressure (step S10-1) or the acquisition of the compression stroke throttle valve position (step S10-2) may be performed first.

Next, the control device 60 obtains the subsequent result detected at the second time point t2 (refer to FIG. 2 ) which is later than the first time point t1 in the same combustion cycle as the compression stroke and where the intake air pressure is higher than the intake air pressure at the first time point t1 Throttle valve position (step S20).

Secondly, the control device 60 estimates the amount of air sucked into the combustion chamber in the next combustion cycle based on the compression stroke intake pressure and compression stroke throttle position obtained in one combustion cycle, as well as subsequent throttle valve positions. , or obtain the required fuel amount (step S30).

Next, the control device 60 controls the fuel injection device 50 to supply fuel before combustion in the next combustion cycle based on the estimated air amount or the obtained required fuel amount (step S40).

FIG. 5 is a diagram showing an example of the four-stroke engine 100 according to this embodiment. As shown in FIG. 5 , the independently throttled four-stroke engine 100 has an independent intake passage 21 in each cylinder 11 for the circulation of air sucked into a single combustion chamber 13 . Each independent intake passage 21 is provided with an independent throttle valve 33 . The control device 60 obtains the compression stroke intake pressure and the compression stroke throttle position detected for each independent intake passage 21, as well as the subsequent throttle position. In an independent throttle type engine, the independent throttle valve 33 can be disposed close to the intake valve 31 . Therefore, the responsiveness of the amount of air sucked into the combustion chamber 13 can be improved.

As mentioned above, the four-stroke engine 100 of this embodiment is provided with: at least one combustion chamber 13; an independent intake passage 21, one end of which is connected to one combustion chamber 13, and the other end is not connected to the combustion chamber 13; an independent throttle valve 33, It is arranged inside the independent air intake passage 21 to adjust the amount of air sucked into the combustion chamber 13; the throttle position detector 42 detects the position of the independent throttle valve 33; the intake pressure detector 43 detects the independent intake air. The intake air pressure between the independent throttle valve 33 of the air passage 21 and the combustion chamber 13; the fuel injection device 50, which supplies fuel to the combustion chamber 13; and the control device 60, which responds to the throttle valve position detector 42 and the intake air pressure. The signal from the detector 43 controls the fuel injection device 50; and when the four strokes starting from the intake stroke defined by the piston position and ending with the compression stroke, expansion stroke and exhaust stroke are defined as one combustion cycle, During at least part of the low-load operation period in which the signal of the intake pressure detector 43 fluctuates greatly within one combustion cycle, the control device 60 controls the intake pressure and the compression stroke based on the compression stroke intake pressure and the compression stroke obtained during the compression stroke in which the intake pressure rises. The position of the independent throttle valve 33 is obtained later than the position of the compression stroke independent throttle valve 33 in the same combustion cycle as the compression stroke, and the intake pressure is later than the time when the position of the compression stroke independent throttle valve 33 is detected. The position of the subsequent independent throttle valve 33 is obtained at the time when the intake air pressure is high, and the amount of air sucked into the combustion chamber 13 in the next combustion cycle is estimated, or the required fuel amount is obtained, and the fuel injection device 50 is controlled. Fuel is supplied before the next combustion.

According to this configuration, the intake air pressure of the compression stroke that has a higher correlation with the air amount among the varying intake air pressures, the position of the compression stroke independent throttle valve 33 detected in the same stroke of the compression stroke, and the position of the compression stroke independent throttle valve 33 are used. The time point in the compression stroke when the position of the independent throttle valve 33 is detected is closer in time to the position of the subsequent independent throttle valve 33 in the next combustion, and the amount of air sucked into the combustion chamber 13 in the next combustion cycle is estimated, or Obtaining the required fuel amount can not only improve the estimation accuracy of the amount of air sucked into the combustion chamber 13 or the required fuel amount under transition and steady states, but also reduce the dependence on manual skills, thereby reducing the steps of system construction. Count.

In the four-stroke engine 100 of this embodiment, the position of the independent throttle valve 33 in the compression stroke and the subsequent position of the independent throttle valve 33 are detection values obtained by the throttle valve position detector 42 .

According to this configuration, control is performed to estimate the air amount or obtain the required fuel amount using the detection value obtained by the throttle position detector 42. Therefore, for example, it is the same as using the predicted value based on the opening and closing speed of the independent throttle valve 33. Compared with other situations, the accuracy of estimating the amount of air or the amount of required fuel can be improved.

The technical scope of the present invention is not limited to the above-described embodiment, and changes may be appropriately made without departing from the gist of the present invention. For example, in the above-mentioned embodiment, the fuel injection device 50 that injects fuel into the independent air intake passage 21 is exemplified as the fuel supply device. However, the invention is not limited to this. A fuel supply device that directly supplies fuel into the combustion chamber 13 may also be used.

10:Engine body 11:Cylinder 12:Crankcase 13: Combustion chamber 14:piston 15: Connecting rod 16:Crankshaft 17: Air intake opening 18:Exhaust opening 19:Mars Plug 21:Independent air intake passage 21a: Atmospheric opening 22:Exhaust passage 31:Intake valve 32:Exhaust valve 33:Independent throttle valve 34:Driving mechanism 41: Crankshaft angle detector 42: Throttle valve position detector 43: Intake pressure detector 50:Fuel injection device 60:Control device 100:Four-stroke engine D1: detection value D2: value (control value) D3:Throttle valve position J1: Injection when the intake valve is closed J2: Injection when the intake valve is opened S10, S10-1, S10-2, S20, S30, S40: steps t1: The first time point t2: The second time point t3: The third time point t4: The fourth time point α, β: injection volume

FIG. 1 is a diagram schematically showing an example of a four-stroke engine. FIG. 2 is a diagram showing an example of the relationship between the detection value of the intake air pressure detected by the intake air pressure detector, the value of the intake air pressure used for control, and the throttle valve position and time. FIG. 3 is a diagram showing another example of the relationship between the detection value of the intake air pressure detected by the intake air pressure detector, the value of the intake air pressure used for control, the throttle valve position, and time. FIG. 4 is a flowchart showing an example of control in the control device of the four-stroke engine. FIG. 5 is a diagram showing an example of a four-stroke engine according to this embodiment.

10:Engine body

11:Cylinder

12:Crankcase

13: Combustion chamber

14:piston

15: Connecting rod

16:Crankshaft

17: Air intake opening

18:Exhaust opening

19:Mars Plug

21:Independent air intake passage

21a: Atmospheric opening

22:Exhaust passage

31:Intake valve

32:Exhaust valve

33:Independent throttle valve

34:Driving mechanism

41: Crankshaft angle detector

42:Throttle valve position detector

43: Intake pressure detector

50:Fuel injection device

60:Control device

100:Four-stroke engine

Claims (2)

An independently throttled four-stroke engine having: at least one combustion chamber; An independent air intake passage, one end of which is connected to one of the above-mentioned combustion chambers, and the other end is not connected to the above-mentioned combustion chamber; An independent throttle valve is provided inside the above-mentioned independent air intake passage to adjust the amount of air sucked into the above-mentioned combustion chamber; A throttle position detector that detects the position of the above independent throttle valve; An intake pressure detector that detects the intake pressure between the above-mentioned independent throttle valve of the above-mentioned independent intake passage and the above-mentioned combustion chamber; A fuel supply device that supplies fuel to the above-mentioned combustion chamber; and A control device that controls the fuel supply device based on signals from the throttle valve position detector and the intake air pressure detector; and When the four strokes starting from the intake stroke defined by the piston position and ending with the compression stroke, expansion stroke and exhaust stroke are defined as one combustion cycle, The above-mentioned control device operates at least part of the low-load operation period in which the signal of the above-mentioned intake air pressure detector fluctuates significantly within one combustion cycle, Based on the compression stroke intake air pressure obtained during the compression stroke in which the intake air pressure shows a rising tone, and the compression stroke throttle valve position detected during the compression stroke, and In the same combustion cycle as the above-mentioned compression stroke, it is obtained at a later time than the time when the above-mentioned compression stroke throttle valve position is obtained, and the intake air pressure is higher than the intake air pressure at the time when the above-mentioned compression stroke throttle valve position is detected. Throttle valve position, The amount of air sucked into the combustion chamber for the next combustion cycle is estimated, or the required fuel amount is obtained, and the fuel supply device is controlled to supply fuel before the next combustion. Such as the independent throttle four-stroke engine of claim 1, wherein The above-mentioned compression stroke throttle valve position and the above-mentioned subsequent throttle valve position are detection values obtained by the above-mentioned throttle valve position detector.