JP2019007463A - Internal combustion engine - Google Patents

Abstract

To weaken reverse-directional revolution airflow occurring in a combustion chamber of a cylinder to intensify in-cylinder flow, regardless of an operational condition of an internal combustion engine.SOLUTION: An internal combustion engine is configured such that suctioned air is split in a process where the suctioned air flows into a combustion chamber of a cylinder through a suction port, then one becomes a desired normal-directional revolution airflow in the combustion chamber, and the other one becomes a revolution airflow reverse thereto in the combustion chamber, wherein at a portion adjacent to flow as the reverse-directional revolution airflow, provided is a plasma actuator configured to generate airflow in a direction of cancelling or weakening the flow.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an internal combustion engine that realizes suitable combustion by controlling a swirling airflow generated in a combustion chamber of a cylinder.

  In a combustion chamber of a cylinder of an internal combustion engine, a tumble that is a vertical swirling air flow along a plane parallel to the central axis (along the piston's forward / backward direction) of the cylinder and the central axis of the cylinder is surrounded by an intake stroke An in-cylinder flow such as a swirl that is a swirling airflow is generated. In the compression stroke, this in-cylinder flow is crushed by the piston moving toward the compression top dead center and collapses into small vortices and turbulent flows. If the in-cylinder flow generated in the combustion chamber is strengthened, it is considered that intake air and fuel can be sufficiently mixed, and combustion can be further promoted or stabilized.

  The intake air flowing into the cylinder through the intake port collides with the umbrella portion of the valve body of the intake valve that is a poppet valve in the process, and is divided. As a result, one of the divided flows becomes a desired swirling airflow in the combustion chamber, and the other becomes a swirling airflow in the opposite direction in the combustion chamber. In order to strengthen the in-cylinder flow, it is required to weaken the latter swirling airflow in the opposite direction as much as possible.

  The following patent document discloses a technical idea that an injector for directly injecting fuel is installed in a combustion chamber of a cylinder, and the injected fuel from the injector is hit against a swirling airflow in a reverse direction to cancel the fuel.

  However, the amount of fuel injected from the injector depends on the operating region such as the engine speed and the required load factor (accelerator opening) of the internal combustion engine at that time. Therefore, it is difficult to cancel the swirling airflow in the reverse direction with the injected fuel in all operating regions.

JP 2009-047073 A

  An object of the present invention is to strengthen the in-cylinder flow by weakening the swirling airflow in the reverse direction generated in the combustion chamber of the cylinder regardless of the operating conditions of the internal combustion engine.

  In the present invention, the intake air is divided in the process of flowing into the combustion chamber of the cylinder through the intake port, one of which is a desired forward swirling air flow in the combustion chamber, and the other is a swirling air flow in the opposite direction in the combustion chamber. In this configuration, an internal combustion engine having a plasma actuator that generates an airflow in a direction that cancels or weakens the flow at a portion adjacent to the flow that becomes the swirling airflow in the reverse direction is configured.

  According to the present invention, the in-cylinder flow can be strengthened by weakening the swirling airflow in the reverse direction generated in the combustion chamber of the cylinder, regardless of the operating conditions of the internal combustion engine.

The figure which shows schematic structure of the internal combustion engine and control apparatus in one Embodiment of this invention. The sectional side view which shows an example of the plasma actuator applied to the internal combustion engine of the embodiment. The sectional side view which shows an example of the plasma actuator applied to the internal combustion engine of the embodiment. The sectional side view which shows an example of the plasma actuator applied to the internal combustion engine of the embodiment. The sectional side view which shows an example of the plasma actuator applied to the internal combustion engine of the embodiment. The sectional side view of one cylinder of the internal combustion engine of the embodiment.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle in the present embodiment. The internal combustion engine in the present embodiment is a spark ignition type 4-stroke gasoline engine, and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). In the vicinity of the intake port of each cylinder 1, an injector 11 for injecting fuel is provided. A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 receives spark voltage generated by the ignition coil and causes spark discharge between the center electrode and the ground electrode. The ignition coil is integrally incorporated in a coil case together with an igniter that is a semiconductor switching element.

  The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port 14 of each cylinder 1. On the intake passage 3, an air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream.

  The exhaust passage 4 for discharging the exhaust guides the exhaust generated by burning the fuel in the cylinder 1 from the exhaust port 15 of each cylinder 1 to the outside. An exhaust manifold 42 and an exhaust purification three-way catalyst 41 are disposed on the exhaust passage 4.

  The exhaust gas recirculation device 2 realizes a so-called high pressure loop EGR, and an external EGR that communicates the upstream side of the catalyst 41 in the exhaust passage 4 and the downstream side of the throttle valve 32 in the intake passage 3. The passage 21, an EGR cooler 22 provided on the EGR passage 21, and an EGR valve 23 that opens and closes the EGR passage 21 and controls the flow rate of EGR gas flowing through the EGR passage 21 are used as elements. The inlet of the EGR passage 21 is connected to the exhaust manifold 42 in the exhaust passage 4 or a predetermined location downstream thereof. The outlet of the EGR passage 21 is connected to a predetermined location downstream of the throttle valve 32 in the intake passage 3, particularly to the surge tank 33.

  An ECU (Electronic Control Unit) 0 that is a control device for an internal combustion engine according to the present embodiment is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface of the ECU 100 includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle output from a crank angle sensor (engine rotation sensor) that detects the rotation angle of the crankshaft and the engine speed. Signal b, accelerator pedal depression amount or throttle valve 32 opening as an accelerator opening (in other words, an engine load required for the internal combustion engine), an accelerator opening signal c output from a sensor, and the temperature of the internal combustion engine Cooling water temperature signal d output from the water temperature sensor for detecting the suggested cooling water temperature, vibration signal e output from the vibration type knock sensor for detecting the magnitude of vibration of the cylinder block containing the cylinder 1, intake passage 3 (especially surge tank 33), output from temperature / pressure sensor that detects intake air temperature and intake pressure An intake temperature / intake pressure signal f, a cam angle signal g output from a cam angle sensor at a plurality of cam angles of an intake camshaft, a sensor that detects whether the brake pedal is depressed or the amount of depression of the brake pedal ( A brake signal h or the like output from a brake switch, a master cylinder pressure sensor, or the like is input.

  From the output interface of the ECU 100, an ignition signal i for the igniter, a fuel injection signal j for the injector 11, an opening operation signal k for the throttle valve 32, an opening operation signal l for the EGR valve 23, and the like. Output.

  The processor of the ECU 100 interprets and executes a program stored in advance in the memory, calculates operation parameters, and controls the operation of the internal combustion engine. The ECU 100 acquires various information a, b, c, d, e, f, g, and h necessary for operation control of the internal combustion engine via the input interface, knows the engine speed, and is filled in the cylinder 1. Estimate the intake volume. Based on the engine speed and intake air amount, etc., the required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, ignition timing, required EGR rate (occupying the intake air) Various operating parameters such as EGR gas ratio and EGR amount) are determined. The ECU 100 applies various control signals i, j, k, and l corresponding to the operation parameters via the output interface.

  Therefore, the internal combustion engine of the present embodiment is provided with the flow control device 10 for operating the airflows 51 and 52 generated in the combustion chamber during the intake stroke of the cylinder 1. The flow control device in this embodiment uses a plasma actuator 10. In the plasma actuator 10, electrodes 201 and 202 that make a pair are arranged with a dielectric 203 interposed therebetween, and an AC voltage or a pulse voltage is applied between the electrodes 201 and 202, so that the surface of the dielectric 203 is near the electrode 201. A plasma 0 and a gas flow 40 are generated.

  As shown in FIGS. 2 to 5, the plasma actuator 10 according to the present embodiment includes a plurality of units 20 each having a pair of an upper electrode 201 and a lower electrode 202 and a dielectric 203 sandwiched between these electrodes. , Arranged intermittently along a certain direction.

  The upper electrode 201 has a width dimension along the front-rear direction (the arrangement direction of the units 20, the horizontal direction in the drawing) smaller than that of the lower electrode 202. In addition, the thickness in the vertical direction (the direction in which the electrodes 201 and 202 sandwich the dielectric 203 or the normal direction of the surface of the dielectric 203; the vertical direction in the figure) is small and thin. The upper electrode 201 of each unit 20 is exposed on the surface of the dielectric 203 or disposed closer to the surface of the dielectric 203 than the lower electrode 202. In the latter case, a coating that does not interfere with plasma generation is applied to the upper electrode 201, or as shown in FIG. 4, the upper electrode 201 is embedded under the surface of the dielectric 203 (where plasma 0 is generated). Thus, the upper electrode 201 can be prevented from directly touching the airflow.

  The lower electrode 202 is greatly expanded in the front-rear direction compared to the upper electrode 201. The lower electrode 202 of each unit 20 may be exposed on the back surface of the dielectric 203 as shown in FIGS. 2 and 4, and embedded in the dielectric 203 as shown in FIGS. 3 and 5. May be. The lower electrode 202 is in a position biased forward with respect to the upper electrode 201 constituting the same unit 20. That is, the upper electrode 201 does not exist immediately above the lower electrode 202.

  The dielectric 203 is typically resin or ceramic. As the dielectric material, it is preferable to employ polymer insulators such as polytetrafluoroethylene and polyimide, and ceramic insulators such as alumina, zirconia, and silicon nitride.

  The shielding unit 30 is provided between the upper electrode 201 of each unit 20 and the lower electrode 202 of another unit 20 adjacent to the unit 20. The shielding unit 30 plays a role of inhibiting generation of plasma between the upper electrode 201 of one unit 20 and the lower electrode 202 of the other unit 20. The shielding part 30 is mainly made of a dielectric material, is located behind the upper electrode 201 of each unit 20 and is at least approximately the same height as the upper surface of the upper electrode 201 from the surface of the dielectric 203 sandwiched between the electrodes 21 and 22. It is approaching. 2, 3, and 5, the height of the shielding part 30 exceeds the upper surface of the upper electrode 201, and the shielding part 30 covers a part of the upper surface of the upper electrode 201. Yes. In the example shown in FIG. 4, the height of the shielding portion 30 is substantially flush with the upper surface of the upper electrode 201, and the surface of the dielectric 203 immediately above the lower electrode 202 is gently continuous. Yes.

  When using this plasma actuator 10, between the upper electrode 201 and the lower electrode 202 of each unit 20, for example, a high voltage of about 1 kV to 10 kV, a pulsating voltage (DC pulse voltage) or an AC voltage of about 1 kHz to 20 kHz. Apply voltage. The applied voltage and frequency are determined according to the dimensions of the electrodes 201 and 202, the distance between the electrodes 201 and 202, the dielectric constant of the dielectric 203, and the like.

  When a voltage is applied between the two electrodes 201 and 202, a plasma 0 is generated on the surface of the dielectric 203 immediately above the lower electrode 202. Due to the plasma 0, an air flow on the surface of the dielectric 203, that is, A gas shock wave 40 is generated. The shock wave 40 flows in a direction from the upper electrode 201 constituting the same unit 20 toward the lower electrode 202, in other words, from the rear to the front. Since the units 20 that generate the plasma 0 are arranged in the front-rear direction, the shock wave 40 flowing on the surface of the dielectric 203 is accelerated and strengthened as it propagates from one unit 20 to another unit 20. .

  In the present embodiment, such a plasma actuator 10 is used to weaken a reverse tumble flow 52 that tends to flow in a direction opposite to the desired forward tumble flow 51 generated in the combustion chamber of the cylinder 1, and thereby mainstream. The tumble flow 51 is strengthened.

As shown in FIG. 6, the intake air 50 flowing into the cylinder 1 through the intake port 14 collides with the umbrella portion of the valve body of the intake valve 141 in the process, and is divided. As a result, one of the divided flows 51 becomes a main tumble flow 51 (represented by a solid line in the figure) in the combustion chamber, and the other becomes a reverse tumble flow 52 (represented by a chain line in the figure) in the combustion chamber. In the internal combustion engine of the present embodiment,
A portion of the intake port 14 adjacent to the flow that becomes the reverse tumble flow 52 (that is, the side far from the center axis of the cylinder 1 (position where the spark plug 12 is attached) in the intake port 14 curved toward the combustion chamber of the cylinder 1) (The lower wall in the figure. The main stream of the tumble flow 51 flows along the wall (on the upper side in the figure) of the intake port 14 closer to the center axis of the cylinder 1).
A portion of the cylinder head at the ceiling of the combustion chamber of the cylinder 1 and adjacent to the reverse tumble flow 52 (a wall surface connected to the inner peripheral wall surface of the intake port 14)
A portion adjacent to the reverse tumble flow 52 in the cylinder bore of the cylinder 1 (a wall surface on the inner peripheral wall surface of the intake port 14)
The plasma actuator 10 is installed in at least one of the above. Then, the plasma actuator 10 generates a gas shock wave 40 (represented by a white arrow in the figure) in a direction that weakens the reverse tumble flow 52, that is, a direction that includes a component in a direction opposite to the reverse tumble flow 52.

  In the present embodiment, the intake air 50 is diverted in the process of flowing into the combustion chamber of the cylinder 1 through the intake port 14, one of which is a desired positive swirling airflow in the combustion chamber, and the other 52 is in the combustion chamber. An internal combustion engine provided with a plasma actuator 10 that generates an air flow 40 in a direction that cancels or weakens the flow 52 in a portion adjacent to the flow that forms the reverse swirl air flow 52 in a reverse swirl air flow. The organization was configured.

  According to the present embodiment, the reverse swirl airflow 52 generated in the combustion chamber of the cylinder 1 can be weakened, and as a result, the desired forward swirl airflow 51 generated in the combustion chamber can be maintained in a strong state. . Therefore, stabilization of the air-fuel mixture combustion and improvement of the initial combustion speed can be expected. Since it is allowed to raise the upper limit of the intake EGR rate, the fuel consumption performance of the internal combustion engine is improved by reducing the pumping loss, and knocking suppression by lowering the combustion temperature (in addition, the ignition timing is set to MBT (Minimum)). (advance for Best Torque)), which is effective in reducing the emission of harmful substances.

  The present invention is not limited to the embodiment described in detail above. For example, the intake air is diverted in the process of flowing into the combustion chamber of the cylinder 1 through the intake port 14, one of which is a desired forward swirl flow in the combustion chamber, and the other is a swirl flow in the opposite direction in the combustion chamber. In the internal combustion engine, the wall surface of the intake port 14, the wall surface of the ceiling portion of the combustion chamber of the cylinder 1, and / or the wall surface of the cylinder bore of the cylinder 1 adjacent to the flow that becomes the swirl flow in the reverse direction, It is also possible to install a plasma actuator 10 that generates an air flow 40 in a direction that cancels or weakens the flow, thereby enhancing the desired swirl flow.

  In addition, the specific configuration of each part can be variously modified without departing from the gist of the present invention.

  The present invention can be applied to an internal combustion engine mounted on a vehicle or the like.

DESCRIPTION OF SYMBOLS 1 ... Cylinder 10 ... Plasma actuator 14 ... Intake port 40 ... Air flow which cancels or weakens a reverse swirl flow 50 ... Intake 51 ... Forward swirl flow 52 ... Reverse swirl flow

Claims (1)

Intake air is divided in the process of flowing into the combustion chamber of the cylinder through the intake port, one of which becomes a desired forward swirling air flow in the combustion chamber, and the other becomes a swirling air flow in the opposite direction in the combustion chamber,
An internal combustion engine provided with a plasma actuator that generates an airflow in a direction that cancels or weakens the flow at a portion adjacent to a flow that becomes a swirling airflow in the reverse direction.

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