JP4124116B2 - In-cylinder supercharged engine - Google Patents

Description

  The present invention relates to an in-cylinder supercharged engine.

In a two-cycle engine, an electromagnetic open / close fuel valve and an electromagnetic open / close air valve are provided facing the fuel reservoir in the front part of the combustion chamber. The open / close fuel valve is opened and closed to inject the required amount of fuel into the fuel sump chamber, and after entering the compression stroke of the next cycle, the electromagnetic open / close air valve is opened to inject air into the fuel sump chamber. When the pressure in the chamber rises, the air-fuel mixture injection valve that responds to the pressure difference between the fuel reservoir and the combustion chamber is automatically opened to inject the air-fuel mixture into the combustion chamber. Some have been closed (see Patent Document 1).
JP-A-7-133724

  By the way, as a technique for increasing the engine output, a technique for supercharging intake air with a turbocharger or a supercharger has been used.

  In this case, the four-cycle gasoline engine has a first intake passage connected to the combustion chamber of the engine, and the intake air that is upstream of the first intake passage and throttles the intake air in the first intake passage. Since it has a throttle valve and an intake collector that stores air downstream of this intake throttle valve, when applying a turbocharger to this four-cycle gasoline engine, as long as an intake compressor is provided upstream of the intake collector, There is a large space volume from the intake compressor to the combustion chamber, and a response delay occurs until the air pressurized by the intake compressor reaches the combustion chamber, resulting in poor acceleration response.

  Accordingly, the present invention provides a second intake passage connected to the combustion chamber of the engine independently of the first intake passage, and a supercharger, a supercharging tank, an air injector, and the like in the second passage. It is an object of the present invention to provide an engine capable of responsively supplying air into a combustion chamber even when a large engine output is required immediately such as during rapid acceleration.

On the other hand, in the technique of Patent Document 1, a small amount of fuel injection amount (about 0.2 s, 0.5 mm ³ / st) and a small amount of air are accurately injected in a short time in a two-cycle engine with an engine rotation speed exceeding 10,000 rpm. Therefore, the technical idea is different from that of the present application for improving responsiveness.

In the present invention, the intake passage connected to the combustion chamber (8) of the engine is composed of first and second independent intake passages (2, 11), of which the first intake passage (2) Comprises an intake throttle valve (3), an intake collector (5), and a mechanically driven intake valve (7). The second intake passage includes a supercharger (12) for pressurizing air, a supercharging tank (13) for storing the pressurized air at a pressure exceeding atmospheric pressure, and a second intake passage ( 11) located at the opening to the combustion chamber (8), the connection of the second intake passage (11) to the combustion chamber (8) is normally cut off, and the target intake air amount corresponding to the accelerator operation amount is obtained. On the other hand, at a predetermined time when the amount of intake air from the first intake passage (2) is insufficient, an air injector (14 ) that injects pressurized air into the combustion chamber (8) in response to the command value. ).

  In addition, the code | symbol was attached | subjected corresponding to description of embodiment, and this invention is not necessarily limited to this.

  According to the present invention, the second intake passage newly connected to the combustion chamber of the engine is provided, and the second intake passage is provided with the supercharger, the supercharging tank, and the air supply device. The response delay at the time of acceleration that could not be solved by the technology of pressurizing the air in the first intake passage with a conventional turbocharger or supercharger can be solved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view for explaining a system according to a first embodiment of the present invention applied to an L-Jetronic gasoline injection engine.

  In the present embodiment, the intake passage connected to the combustion chamber 8 of the engine is composed of first and second independent intake passages 2 and 11, and the first intake passage 2 includes an intake throttle valve. 3, an intake collector 5, and an intake valve 7. That is, the air is metered by the intake throttle valve 3 positioned upstream of the first intake passage 2, and the metered air is temporarily stored in the intake collector 5 positioned downstream of the intake throttle valve 3. The intake valve 7 located at the opening of the first intake passage 2 to the combustion chamber 8 is normally disconnected from the connection of the first intake passage 2 to the combustion chamber 8 and is an engine-driven intake valve camshaft ( The piston 9 is mechanically driven by an unillustrated) and is opened in the suction stroke from the top dead center toward the bottom dead center. When the intake valve 7 is open, air stored in the intake collector 5 is introduced into the combustion chamber 8 of each cylinder through the intake port 6. In this case, the amount of air introduced into the combustion chamber 8 is determined by the pressure difference between the intake collector 5 and the combustion chamber 8 and the area of the gap between the intake valve 7 and the intake port wall.

  The intake throttle valve 3 is driven by a motor 4, and the motor current of the motor 4 is controlled by an engine control module 31.

  Fuel is injected and supplied into the intake port 6 at a predetermined timing from a fuel injector 21 disposed in the intake port 6 of each cylinder.

  On the other hand, the second intake passage 11 includes a supercharger 12, a supercharging tank 13, and an air injector 14 (air supply device). That is, the air is pressurized by the supercharger 12. Here, the supercharger 12 is an electric supercharger that pressurizes air with an electric motor. However, the present invention is not limited to this, and a turbocharger that pressurizes with exhaust pressure or a supercharger that pressurizes with engine shaft output may be used.

  After the air pressurized by the supercharger 12 is temporarily stored in the supercharging tank 13 at a pressure exceeding the atmospheric pressure, the air stored in the supercharging tank 13 is higher in pressure than the atmospheric pressure. Is distributed to an air injector 14 provided facing the air. The air injector 14 located at the opening of the second intake passage 11 to the combustion chamber 8 is normally disconnected from the connection of the second intake passage 11 to the combustion chamber 8, and is commanded from the engine control module 31. In response, the air injector 14 directly injects and supplies high-pressure air from the supercharging tank 13 into the combustion chamber 8. In this case, the amount of air introduced into the combustion chamber 8 is determined by the pressure difference between the supercharging tank 13 and the combustion chamber 8 and the opening area of the air injector 14.

  The timing at which the air injector 14 is opened (predetermined timing) is after the intake valve 7 is closed, that is, the engine compression stroke. Actually, it is desirable immediately after the intake valve 7 is closed. The reason why the air is injected and supplied by the air injector 14 after the intake valve 7 is closed is to prevent the air injected into the combustion chamber 8 from flowing backward from the open intake valve 7 to the intake port 5. .

  Also, the air injection start timing immediately after the intake valve 7 is closed is that the air is injected into the combustion chamber 8 in a state where the inside of the combustion chamber 8 is pressurized by the compression of the piston 9. It is necessary to overcome the internal pressure and inject the air. If this happens, the air injector 14 and the supercharging tank 13 are increased in size and the cost is increased. Therefore, in order to avoid this, the inside of the combustion chamber 8 is not excessively pressurized by compression. This is because the air injection supply is ended.

  Also, the air injector 14 does not open under operating conditions where engine output is not so necessary, such as in a low load state. For this reason, in the low load state, the fuel injected from the fuel injector 21 is mixed with the air flowing in via the intake port 6 when the intake valve 7 is open to form an air-fuel mixture. Is closed in the combustion chamber 8 and compressed by the piston 9 rising. Further, when there is a large output request (when there is a request), an air amount that is insufficient depending on the first intake passage 2 is injected and supplied by the air injector 14 in the compression stroke after the intake valve 7 is closed, This additional supplied air further promotes fuel vaporization.

  The air-fuel mixture thus formed is ignited by the spark plug 41 and burned at a predetermined crank angle before the compression top dead center. The gas pressure due to the combustion works to push down the piston 9, and the reciprocating motion of the piston 9 is converted into the rotational motion of the crankshaft 10. The combusted gas (exhaust gas) is discharged into the exhaust passage 43 when the exhaust valve 42 is opened.

  In the engine control module 31 to which an accelerator operation amount signal from the accelerator sensor 32, a crank angle signal from the crank angle sensor 33, and an intake air amount signal from the air flow meter 34 are input, the motor 4 is connected via the motor 4 in accordance with operating conditions. Then, the opening degree of the intake throttle valve 3 is controlled, the fuel injector 21 is driven to control the fuel injection amount, the ignition timing is set, and the ignition plug 41 is ignited.

  Here, the control executed by the engine control module 31 controls the intake air amount and the fuel supply amount so as to obtain the target engine torque and the target air-fuel ratio according to the operating state of the engine. This is described in detail in JP-A-9-287513. In brief, a predetermined map is searched from the accelerator operation amount APS detected by the accelerator sensor 32 and the engine speed Ne calculated based on the signal from the crank angle sensor 33, and the theoretical air-fuel ratio is searched. At this time, a reference target intake air amount tTP, which is an intake air amount that can obtain a target torque commensurate with APS and Ne, is obtained, and a value obtained by dividing this by the target equivalent ratio tDML is calculated as a target intake air amount tTP ′. Then, a predetermined map is retrieved from the target intake air amount tTP ′ and the engine speed Ne to obtain the target throttle valve opening tTPS, and the intake throttle valve 3 is controlled so as to coincide with the target throttle valve opening tTPS. To do.

  Further, a basic value amount injection pulse width TP corresponding to the intake air amount per intake stroke at the stoichiometric air-fuel ratio is calculated from the intake air amount Qa per unit time detected by the air flow meter 34 and the engine speed, Is multiplied by the target equivalent ratio tDML as the effective fuel injection pulse width TE, and the invalid fuel pulse width TS is added to this value to obtain the final fuel injection pulse width TI. The injector 21 is opened.

  On the premise of the engine that controls the intake air amount and the fuel injection amount, the supercharger 12 and the air injector 14 are controlled as follows in the present invention. That is, since the pressure in the supercharging tank 13 needs to be adjusted to a preferable pressure (target supercharging pressure) at the time when air is injected into the combustion chamber 8 by the air injector 14, the pressure in the engine control module 31 is Based on the signal from the sensor 15, the pressure in the supercharging tank 13 is controlled. For example, when the actual pressure in the supercharging tank 13 is lower than the target supercharging pressure, the electric supercharger 12 is operated to increase the actual pressure to the target supercharging pressure, and the actual pressure in the supercharging tank 13 is increased. Is higher than the target supercharging pressure, a relief valve (not shown) is opened to release the air in the supercharging tank 13 to the atmosphere, and the actual pressure in the supercharging tank 13 is returned to the target supercharging pressure.

  On the other hand, if the target intake air amount tTP ′ is the same as the actual intake air amount Qa detected by the air flow meter 34 (the target intake air amount tTP ′ is an amount per cylinder per cylinder, this intake air amount Qa is also the same. And the difference from the unit (which needs to be converted into a unit) is calculated as an insufficient air amount ΔQ (= tTP′−Qa), and from the insufficient air amount ΔQ and the pressure in the supercharging tank 13 detected by the pressure sensor 15. The air injection pulse width is determined, and the air injector 14 is opened during the air injection pulse width immediately after the intake valve 7 is closed as shown in FIG.

  Here, the operation of the present embodiment will be described.

  In the present embodiment, when the accelerator pedal is suddenly depressed to the full during the steady state (during rapid acceleration), the target intake air amount is depressed from the value tTP′1 in the steady state. Consider a case where the corresponding value tTP′2 increases stepwise. If the intake throttle valve 3 is opened to the fully open position immediately in response to the accelerator pedal operation amount APS, the intake air amount at the air flow meter 34 position also corresponds to the fully open position of the intake throttle valve 3 from the value Qa1 in the steady state. The value Qa2 increases with a response delay.

  However, since the position of the air flow meter 34 is upstream of the intake throttle valve 3, and there is a large air volume in the intake passage 2 from the position of the air flow meter 34 to the combustion chamber 8, the amount of intake air flowing into the combustion chamber 8 is The value Qa1 at the steady state remains for a while, and the amount of air obtained by subtracting this Qa1 from tTP′2 is insufficient in the combustion chamber 8.

  At this time, if it is considered that the intake air amount Qa (≈Qa1) detected by the air flow meter 34 is smaller than the target intake air amount tTP ′ (= tTP′2), the difference air amount ΔQ (= tTP′2−Qa1). ) Is immediately injected into the combustion chamber 8 from the air injector 14 that receives a command from the engine control module 31. In other words, since the intake air amount (= Qa1 + ΔQ = tTP′2) equal to the target intake air amount tTP ′ can be supplied into the combustion chamber 8, the present embodiment can be used even during sudden acceleration when the accelerator pedal is suddenly depressed. For example, a target torque commensurate with the accelerator operation amount APS and the engine rotational speed Ne at that time is immediately obtained, thereby improving the acceleration response.

  On the other hand, since the second intake passage 11 is not provided in the technique described in Japanese Patent Laid-Open No. 9-287513, the intake air amount Qa detected by the air flow meter 34 must be smaller than the target intake air amount tTP ′. For example, the amount of air (tTP′−Qa) corresponding to the difference is insufficient in the combustion chamber 8, and the target torque corresponding to the accelerator operation amount APS and the engine rotational speed Ne at that time cannot be obtained. .

Thus, according to the present embodiment (the invention described in claim 1 ), the second intake passage 11 connected to the combustion chamber 8 of the engine is newly provided, and the second intake passage 11 is supercharged. a machine 12, a supercharge tank 13, so includes an air injector 1 4, turbocharger or supercharger with the first response delay at the time of acceleration that could not be solved in an air intake passage 2 by pressurizing technique is conventional Could be solved.
Further, since the air injector 14 is driven when the intake air amount Qa from the first intake passage 2 is insufficient with respect to the target intake air amount tTP ′ corresponding to the accelerator operation amount, the supercharger 12 is always operated. Since it is not necessary to pressurize only the insufficient air, it is possible to improve the efficiency of supercharging.

According to the present embodiment (the invention described in claim 2 ), since the predetermined timing, which is the timing for opening the air injector 14, is when the intake valve 7 is closed, the air injected into the combustion chamber 8 However, it is possible to prevent a reverse flow from the open intake valve 7 to the intake port 6.

  In the embodiment, the fuel injector 21 is provided facing the intake port 6. However, the present invention is not limited to this, and for example, the fuel injector 21 may be provided directly facing the combustion chamber 8.

  The air injector 14 is provided on the upper surface 8a of the combustion chamber 8, but is not limited thereto. For example, in an engine that directly injects fuel into the combustion chamber 8, the fuel injector is provided facing the cylinder surface 8b (the left cylinder surface in FIG. 1) near the intake port 6, but this fuel injector is replaced. An air injector can be provided. Further, when used as an engine for directly injecting and supplying fuel into the combustion chamber 8, an air injector can be provided in the vicinity of the fuel injector. Furthermore, it can also be provided facing the right cylinder surface in FIG.

In the embodiment, the case where the delay in supplying the air to the combustion chamber 8 at the time of acceleration is compensated by the air supply from the second intake passage 11 has been described. However, the air is directly introduced into the combustion chamber 8 by the air injector 14. because it is injecting and supplying arrangement, Ru can be used to produce a gas flow to the air injector 14 into the combustion chamber 8. In this case, the predetermined time for injecting and supplying air need not be limited to when the intake valve 7 is closed, but may be immediately before the intake valve 7 is closed. Further, when the supercharging tank 13 does not have the pressure to inject air from the air injector 14 in opposition to the pressure in the combustion chamber 8, it is desirable to stop the injection supply by the air injector 14 (the invention according to claim 3 ). ).

  In the embodiment, the L-Jetronic gasoline injection engine has been described, but the present invention can also be applied to a D-Jetronic gasoline injection engine.

1 is a schematic configuration diagram of a first embodiment of the present invention. The wave form diagram for demonstrating the effect | action at the time of sudden acceleration.

Explanation of symbols

2 First intake passage 3 Intake throttle valve 5 Intake collector 7 Intake valve 8 Combustion chamber 11 Second intake passage 12 Supercharger 13 Supercharged tank 14 Air injector (air supply device)
31 Engine control module

Claims (3)

An intake passage connected to the combustion chamber of the engine is composed of two independent passages, a first intake passage and a second intake passage,
In the first intake passage,
An intake throttle valve that is upstream of the first intake passage and throttles intake air;
An intake collector downstream of the intake throttle valve for storing air;
An intake valve located at an opening to the combustion chamber of the first intake passage and communicating with and blocking the combustion chamber of the first intake passage;
In the second intake passage,
A supercharger that pressurizes the air;
A supercharging tank that stores this pressurized air at a pressure exceeding atmospheric pressure,
Located at the opening of the second intake passage to the combustion chamber, the connection of the second intake passage to the combustion chamber is normally cut off, and the first intake air amount corresponding to the accelerator operation amount is compared with the first intake air amount. An air injector that injects pressurized air into the combustion chamber in response to the command value at a predetermined time when the amount of intake air from the intake passage is insufficient ;
An in-cylinder supercharged engine comprising: The in-cylinder supercharging engine according to claim 1, wherein the predetermined time is when the intake valve is closed . According to claim 1 or 2 wherein in the absence of pressure by air injected from the air injector in opposition to the pressure of the combustion chamber to supercharge tank is characterized <br/> to abort the injection supply by the air injector The in-cylinder supercharged engine described in 1.

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