JP6253478B2 - Internal combustion engine - Google Patents

Description

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

  In an ignition device mounted on a general spark ignition type internal combustion engine, a high voltage generated in the ignition coil when the igniter extinguishes is applied to the center electrode of the ignition plug, so that the center electrode of the ignition plug is grounded. A spark discharge is caused between the electrodes and ignited.

  Recently, in order to ensure that the air-fuel mixture in the combustion chamber of the cylinder is ignited and a stable flame can be obtained, the high frequency output from the high frequency oscillator or the microwave output from the magnetron is radiated into the combustion chamber. An “active ignition” method has been attempted (see, for example, the following patent document). According to the active ignition method, a high-frequency electric field or a microwave electric field is formed in the space between the center electrode and the ground electrode, and the plasma generated in this electric field grows to form a large flame nucleus that starts flame propagation combustion. Can be generated.

JP, 2014-029128, A

  The center electrode and the ground electrode of the ignition plug of the internal combustion engine are gradually worn out as the period of use becomes longer. In particular, when the above-described active ignition method is used, the wear of the active ignition method is remarkably accelerated, so that frequent check and replacement of the spark plug is required.

  An object of the present invention is to improve convenience by reducing the replacement frequency of a spark plug in an internal combustion engine that performs active ignition.

  In the present invention, the spark discharge generated between the center electrode of the spark plug and the ground electrode interacts with the electric field radiated into the combustion chamber using the center electrode of the spark plug as an antenna, thereby generating plasma in the combustion chamber to generate fuel. An internal combustion engine capable of performing active ignition that ignites the first ignition plug and the second ignition plug installed in the same cylinder, an AC oscillator that outputs an AC voltage, and the AC oscillator A first half-wave rectifier that passes a half-wave of the AC voltage and outputs the half-wave toward the center electrode of the first spark plug; and the first half-wave of the AC voltage supplied from the AC oscillator An internal combustion engine including a second half-wave rectifier that passes a half-wave blocked by the rectifier and outputs the half-wave toward the center electrode of the second spark plug is configured.

  According to the present invention, in an internal combustion engine that performs active ignition, it is possible to improve convenience by reducing the replacement frequency of the spark plug.

The figure which shows schematic structure of the internal combustion engine of one Embodiment of this invention. The circuit diagram of the ignition system of the internal combustion engine of the embodiment. The figure explaining the structure of the electric field generator accompanying the ignition system of the internal combustion engine of the embodiment. The circuit diagram of the H bridge which is an element of the electric field generator.

  An embodiment 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 of this embodiment is a direct injection type four-stroke gasoline engine, and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). Each cylinder 1 is provided with an injector 11 for injecting fuel at a position facing the combustion chamber.

  Spark plugs 12 and 13 are attached to the ceiling of the combustion chamber of each cylinder 1. In particular, in the internal combustion engine of the present embodiment, a plurality of spark plugs 12 and 13 are installed for one cylinder 1. The first spark plug 12 among them causes a so-called positive discharge when a positive voltage is applied to the center electrode thereof, that is, a discharge in which electrons move from the ground electrode toward the center electrode. On the other hand, a negative voltage is applied to the center electrode of the second spark plug 13 to cause a so-called negative discharge, that is, a discharge in which electrons move from the center electrode toward the ground electrode. In the internal combustion engine of this embodiment, when igniting the air-fuel mixture filled in the combustion chamber of the cylinder 1, the first spark plug 12 is used, the second spark plug 13 is used, or both are ignited. It is possible to select whether to use the plugs 12 and 13.

  FIG. 2 shows an electric circuit of the ignition system. The first ignition coil 14 supplies a positive voltage to be applied to the first spark plug 12. The first ignition coil 14 is integrally incorporated in the coil case together with the first igniter 15 that is a semiconductor switching element. When the igniter 15 receives an ignition signal i1 from an ECU (Electronic Control Unit) 0, which is a control device for the internal combustion engine, the igniter 15 is first ignited and a current flows to the primary side of the ignition coil 14, and immediately after the ignition timing. The igniter 15 is extinguished to interrupt this current. Then, a self-induction action occurs, and a high voltage is generated on the primary side of the ignition coil 14. Since the primary side and the secondary side share a magnetic circuit and magnetic flux, a higher positive induced voltage is generated on the secondary side. This induced voltage is applied to the center electrode of the first spark plug 12, and a spark discharge is generated between the center electrode and the ground electrode.

  Similarly, the second ignition coil 16 supplies a negative voltage to be applied to the second spark plug 13. The second ignition coil 16 is also integrally incorporated in the coil case together with the second igniter 17 that is a semiconductor switching element. When the igniter 17 receives the ignition signal i2 from the ECU (Electronic Control Unit) 0, the igniter 17 is ignited and a current flows to the primary side of the ignition coil 16, and the igniter 17 is extinguished at the ignition timing immediately after that. This current is cut off. Then, a high voltage is generated on the primary side of the ignition coil 16, and a higher negative induced voltage is generated on the secondary side. This induced voltage is applied to the center electrode of the second spark plug 13, and a spark discharge is generated between the center electrode and the ground electrode.

  In the internal combustion engine of the present embodiment, an electric field generator 6 for generating an electric field in the combustion chamber of the cylinder 1 is attached to the ignition system. The electric field generator 6 generates a high frequency for the purpose of generating plasma in the combustion chamber. As shown in FIGS. 3 and 4, the electric field generator 6 includes a circuit that uses a vehicle-mounted battery as a power source and converts low-voltage direct current into high-voltage alternating current. Specifically, a DC-DC converter 61 that boosts a DC voltage of about 12 V provided by the battery to 100 V to 500 V, and an AC oscillator that outputs an AC high frequency using the DC voltage output from the DC-DC converter 61. The high-frequency generator circuit 62, the step-up transformer 63 that boosts the AC high-frequency output from the high-frequency generator circuit 62 to a higher voltage, and the positive half-wave of the AC high-frequency boosted by the boost transformer 63 The first half-wave rectifier 64 and the second half-wave rectifier 65 that pass the negative half-wave of the AC high-frequency boosted by the step-up transformer 63 are used as constituent elements.

  The DC-DC converter 61 can change the magnitude of the direct-current drive voltage applied to the high-frequency generation circuit 62 in response to the instruction 1 from the ECU 0, and consequently the amplitude of the high-frequency voltage downstream of the step-up transformer 63. Can be changed. The high-frequency voltage downstream of the step-up transformer 63 preferably has a frequency of about 200 kHz to 3000 kHz and an amplitude of about 3 kVp-p to 10 kVp-p.

  In the present embodiment, the high frequency generation circuit 62 is an H bridge circuit that converts the DC voltage output from the DC-DC converter 61 into an AC voltage. FIG. 4 shows a configuration example of this H-bridge circuit.

  The first half-wave rectifier 64 is formed using, for example, a diode, and has an anode connected to the output signal line of the secondary winding of the step-up transformer 63 and a cathode connected to the first ignition coil 14. Connect to the mixer 7 which is a node. The first half-wave rectifier 64 half-wave rectifies the alternating high-frequency wave downstream of the step-up transformer 63 to generate a positive voltage pulsating current, and also positively flows from the secondary side of the ignition coil 14 at the ignition timing. It plays a role of blocking the high voltage pulse current.

  The second half-wave rectifier 65 is also formed by using, for example, a diode, and has a cathode connected to the output signal line of the secondary winding of the step-up transformer 63 and an anode connected to the second ignition coil 16. Is connected to the mixer 8 which is a nodal point. The second half-wave rectifier 65 half-wave rectifies the alternating high-frequency wave downstream of the step-up transformer 63 to generate a negative voltage pulsating flow and negatively flows from the secondary side of the ignition coil 16 at the ignition timing. It plays a role of blocking the high voltage pulse current.

  The high-frequency pulsating voltage generated by the electric field generator 6 is applied to the center electrodes of the spark plugs 12 and 13. More specifically, a positive pulsating voltage is applied to the center electrode of the first spark plug 12 via the mixer 7, and a negative pulsating voltage is applied to the center electrode of the second spark plug 13 via the mixer 8. Apply to. That is, the center electrode of the spark plugs 12 and 13 facing the combustion chamber of the cylinder 1 is an antenna that radiates an electric field. Thereby, a high frequency electric field is formed in the space between the center electrode of the spark plugs 12 and 13 and the ground electrode in the combustion chamber. Then, a plasma is generated by performing a spark discharge in a high-frequency electric field, and this plasma generates a large radical plasma flame nucleus that starts flame propagation combustion.

  In the above, the flow of electrons due to the spark discharge and the ions and radicals generated by the spark discharge are vibrated and meandered by the influence of the electric field, resulting in a long path length and a dramatic increase in the number of collisions with surrounding water and nitrogen molecules. This is due to the increase. Water molecules and nitrogen molecules that have been struck by ions and radicals become OH radicals and N radicals, and the surrounding gas that has been struck by ions and radicals is also ionized, that is, a plasma state. In addition, the region of ignition of the air-fuel mixture increases and the flame kernel also increases. As a result, the two-dimensional ignition by only the spark discharge is amplified to the three-dimensional ignition, and the combustion rapidly propagates into the combustion chamber and expands at a high combustion speed.

  In the case of performing active ignition, the timing at which a high frequency is applied to the center electrode of the spark plugs 12 and 13 is usually almost simultaneously with the start of spark discharge, immediately before the start of spark discharge, or just after the start of spark discharge.

  Of course, the internal combustion engine of the present embodiment can also ignite the air-fuel mixture by conventional spark ignition that is not active ignition, that is, spark discharge that does not involve emission of a high-frequency electric field from the center electrodes of the spark plugs 12 and 13. In situations where it is easy to ignite and burn stably (it is unlikely to cause a combustion failure), it is conceivable to perform conventional spark ignition to suppress power consumption.

  An intake passage 3 for supplying intake air to the cylinder 1 of the internal combustion engine takes in air from the outside and guides it to the intake port 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 exhausting the exhaust from the cylinder 1 guides the exhaust generated as a result of burning the fuel in the cylinder 1 from the exhaust port 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 external EGR (Exhaust Gas Recirculation) device 2 realizes a so-called high pressure loop EGR, and an EGR passage 21 communicating 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 EGR cooler 22 provided on the EGR passage 21 and the EGR valve 23 that opens and closes the EGR passage 21 and controls the flow rate of the 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, specifically to a surge tank 33.

  The ECU 0 that controls operation of the internal combustion engine is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal b output from an engine rotation sensor that detects the rotation angle and engine speed of the crankshaft, and depression of an accelerator pedal. An accelerator opening signal c output from a sensor that detects the amount or the opening of the throttle valve 32 as an accelerator opening (so-called required load), and a brake pedaling amount signal d output from a sensor that detects the amount of depression of the brake pedal The intake air temperature / intake pressure signal e output from the temperature / pressure sensor for detecting the intake air temperature and the intake pressure in the intake passage 3 (particularly the surge tank 33), and the water temperature sensor for detecting the cooling water temperature of the internal combustion engine are output. Output from the cam angle sensor at a plurality of cam angles of the cooling water temperature signal f and the intake camshaft or exhaust camshaft. A cam angle signal g, atmospheric pressure signal h or the like to be outputted from the atmospheric pressure sensor for detecting the atmospheric pressure is inputted.

  From the output interface, the ignition signal i1 for the first igniter 15 associated with the first ignition plug 12, the ignition signal i2 for the second igniter 17 associated with the second ignition plug 13, and the injector 11 On the other hand, the fuel injection signal j, the opening operation signal k for the throttle valve 32, the voltage command signal l for commanding the magnitude of the drive voltage output from the DC-DC converter 61 to the DC-DC converter 61, EGR An opening operation signal m or the like is output to the valve 23.

  The processor of the ECU 0 interprets and executes a program stored in the memory in advance, calculates operation parameters, and controls the operation of the internal combustion engine. The ECU 0 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, intake air amount, etc., the required fuel injection amount, fuel injection timing (including the number of fuel injections per combustion), fuel injection pressure, ignition timing, and high-frequency electric field applied to the combustion chamber Various operating parameters such as whether or not to perform, the strength of the electric field, and the required EGR rate (or EGR amount) are determined. The ECU 0 applies various control signals i1, i2, j, k, l, m corresponding to the operation parameters via the output interface.

  In the present embodiment, the spark discharge generated between the center electrode of the spark plugs 12 and 13 and the ground electrode interacts with the electric field radiated into the combustion chamber using the center electrode of the spark plugs 12 and 13 as an antenna. An internal combustion engine capable of performing active ignition that generates plasma in a room and ignites fuel, and outputs an AC voltage to a first spark plug 12 and a second spark plug 13 installed in the same cylinder 1 An AC oscillator 62, a first half-wave rectifier 64 that passes a half-wave of the AC voltage generated from the AC oscillator 62 and outputs the half-wave toward the center electrode of the first spark plug 12, and the AC oscillator The second half of the AC voltage generated from the first half-wave rectifier 64 passes through the half-wave blocked by the first half-wave rectifier 64 and is output toward the center electrode of the second spark plug 13. And configure the internal combustion engine and a rectifier 65.

  According to the present embodiment, since the plurality of spark plugs 12 and 13 installed in one cylinder 1 can be used while being switched as appropriate, the wear of the electrodes of each spark plug 12 and 13 is delayed to extend the life thereof. It becomes possible. Therefore, the frequency of inspection and replacement of the spark plugs 12 and 13 is reduced, and convenience is improved.

  The present invention is not limited to the embodiment described in detail above. For example, the frequency of the AC voltage output from the AC oscillator 62 or the frequency of the pulsating flow after half-wave rectification applied to the center electrode of the spark plugs 12 and 13 is not limited to the high frequency band but belongs to the microwave band or the like. It may be.

  The internal combustion engine to which the present invention is applied is not limited to a so-called gasoline direct injection engine. Naturally, it is also conceivable to apply the present invention to a diesel engine, a HCCI (homogeneous-charge compression ignition) engine, or the like.

  Furthermore, the present invention may be applied to a port injection type internal combustion engine that injects fuel to the intake port.

  Other specific configurations of each part can be variously modified without departing from the spirit of the present invention.

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

0 ... Control unit (ECU)
DESCRIPTION OF SYMBOLS 1 ... Cylinder 12 ... 1st spark plug 13 ... 2nd spark plug 62 ... AC oscillator 64 ... 1st half wave rectifier 65 ... 2nd half wave rectifier

Claims (1)

Active to generate a plasma in the combustion chamber and ignite the fuel by interacting the spark discharge generated between the center electrode of the spark plug and the ground electrode with the electric field radiated in the combustion chamber using the center electrode of the spark plug as an antenna An internal combustion engine capable of performing ignition,
A first spark plug and a second spark plug installed in the same cylinder;
An AC oscillator that outputs AC voltage;
A first half-wave rectifier that passes a half-wave of the AC voltage generated from the AC oscillator and outputs the half-wave toward the center electrode of the first spark plug;
A second half-wave rectifier that passes a half-wave that is interrupted by the first half-wave rectifier out of the alternating-current voltage generated from the alternating-current oscillator and outputs the half-wave toward the center electrode of the second spark plug; An internal combustion engine provided.

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