JP2016089659A - Control device of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further improve fuel consumption performance of a vehicle loading a spark ignition type internal combustion engine.SOLUTION: A magnitude of electric energy input to an ignition plug disposed on a cylinder is increased according to an operation region of an internal combustion engine. In a case where the difference between a fuel consumption rate obtained by increasing electric energy input to the ignition plug without accompanying power generation by a power generator generating power by receiving supply of rotary torque from the internal combustion engine, and a fuel consumption rate in consideration of deterioration of a fuel consumption rate due to power generation of the power generator corresponding to the increase of the electric energy input to the ignition plug, is large, an upper limit set to a power generation rate as a ratio of the increase of an actual power generation amount of the power generator and the increase of power generation amount necessary for compensating the increase of the electric energy input to the ignition plug, to be lowered in comparison with a case where the difference is small, and shortage of the power generation amount is compensated by regenerative braking in deceleration of a vehicle.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a spark ignition type internal combustion engine and a vehicle control device equipped with a generator associated therewith.

  In a spark ignition type internal combustion engine, a spark plug for igniting an air-fuel mixture filled in a cylinder receives a voltage induced by an ignition coil and causes a spark discharge between a center electrode and a ground electrode. To do.

  An igniter having a semiconductor switching element is provided on an electric circuit for energizing the ignition coil. When the igniter semiconductor switch is ignited, a current flows to the primary side of the ignition coil. The primary current flowing through the primary coil increases while firing the semiconductor switch. Thereafter, when the semiconductor switch is extinguished at an appropriate spark ignition timing, a high voltage is generated on the primary side of the ignition coil by the self-induction action at the moment when the primary current is cut off. Then, a higher induced voltage is generated in the secondary side coil sharing the magnetic circuit and magnetic flux with the primary side. By applying this high induced voltage to the center electrode of the spark plug, a spark discharge is generated between the center electrode and the ground electrode.

  The magnitude of the electric energy input to the spark plug for spark ignition depends on the magnitude of the primary current flowing through the primary coil of the ignition coil when the semiconductor switch is extinguished. That is, the longer the energization time for the primary coil, the greater the electrical energy input to the spark plug.

  As the electrical energy input to the spark plug, that is, the spark discharge energy, increases, the ignitability of the air-fuel mixture in the cylinder improves and the combustion becomes better. The energy can be expected to increase (see the following patent document).

JP 2014-163348 A

  However, the electrical energy input to the spark plug is originally generated by a generator driven by the internal combustion engine. Increasing the electrical energy input to the spark plug means that the mechanical energy consumed by the generator for power generation increases. Therefore, simply increasing the electric energy input to the spark plug in the dark clouds does not necessarily improve the fuel efficiency of the internal combustion engine. On the other hand, the efficiency may deteriorate.

  In the low-load operation region where the fuel injection amount is small, the operation region where the EGR rate is large, or the situation where the air-fuel ratio is lean, the ignition combustion of the air-fuel mixture is significantly improved by increasing the electric energy input to the spark plug. The effect of improving the heat-mechanical energy conversion efficiency can be expected. On the other hand, in a relatively high load operating region with a large amount of fuel injection, the air-fuel mixture is easy to ignite in the first place, flame propagation is good, and heat-mechanical energy conversion efficiency is increased by increasing the electric energy input to the spark plug. The improvement effect is expected to be negligible.

  Furthermore, the efficiency of power generation by the generator also varies depending on the rotational speed of the generator and the magnitude of torque input to the generator. The power generation efficiency in the low rotation operation region is lower than that in the medium rotation or high rotation operation region.

  An object of the present invention is to further improve the fuel efficiency of a vehicle equipped with a spark ignition type internal combustion engine.

  In the present invention, a spark ignition type internal combustion engine that ignites an air-fuel mixture in a cylinder by causing a spark discharge between electrodes of an ignition plug installed in the cylinder, and a generator that generates electric power by receiving supply of rotational torque from the internal combustion engine Is a vehicle control device that increases the magnitude of electrical energy input to the spark plug in accordance with the operating range of the internal combustion engine (in a specific operating range, the magnitude of electrical energy input to the spark plug). The fuel consumption rate obtained without power generation by the generator and the fuel consumption rate brought about by causing the generator to generate power corresponding to the electrical energy input to the spark plug. When the difference from the fuel consumption rate taking into account the deterioration is large, compared to the case where the difference is small, the actual power generation increment of the generator and the electric energy input to the spark plug In addition to lowering the upper limit set for the power generation rate, which is the ratio of the increase in the amount of power generation necessary to compensate for the increase (in certain operating areas, the upper limit of the power generation rate may be 0) The controller configured to compensate for the insufficient power generation amount by regenerative braking during vehicle deceleration.

  In addition, in the present invention, a spark ignition internal combustion engine that ignites an air-fuel mixture in a cylinder by causing a spark discharge between the electrodes of an ignition plug installed in the cylinder, and receives the supply of rotational torque from the internal combustion engine to generate electric power. A control device for a vehicle in which a generator is mounted, and in an operation region where the improvement in the fuel consumption rate obtained by increasing the electric energy input to the spark plug from a certain predetermined value is large, the operation with a small improvement Compared to the region, it is necessary to increase the electric energy input to the spark plug more than the predetermined value and to compensate for the increase in the actual power generation amount of the generator and the increase in the electric energy input to the spark plug. The upper limit set for the power generation rate, which is the ratio to the increase in power generation amount, is lower (in some operating areas, the upper limit of the power generation rate may be 0) and is insufficient Coulometric control unit supplemented by regenerative braking during deceleration of the vehicle.

  ADVANTAGE OF THE INVENTION According to this invention, the further improvement of the fuel consumption performance of the vehicle carrying a spark ignition type internal combustion engine can be aimed at.

The figure which shows schematic structure of the internal combustion engine in one Embodiment of this invention. The circuit diagram of the spark ignition device in the embodiment. The figure which shows transition of the primary current which flows through the primary side coil of an ignition coil in the period from ignition of an igniter to spark ignition. The figure which shows each transition of the combustion pressure and the ionic current in the cylinder of an internal combustion engine. The figure which shows typically the relationship between the ignition energy and fuel consumption in a certain driving | running | working area | region. The figure which shows typically the relationship between the ignition energy and fuel consumption in another driving | operation area | region. The figure which shows typically the relationship between the deterioration part of the fuel consumption brought about by making a generator produce electric power, and the upper limit of the power generation rate of a 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 in the present embodiment is a spark ignition type four-stroke 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 intake passage 3 for supplying intake air 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 discharging the exhaust 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 exhaust gas recirculation device 2 realizes a so-called high-pressure loop EGR in which a part of the exhaust gas flowing through the exhaust passage 4 is returned to the intake passage 3 and mixed with the intake air. The EGR device 2 includes an external EGR passage 21 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, an EGR cooler 22 provided on the EGR passage 21, and an EGR passage 21. And an EGR valve 23 that controls the flow rate of the EGR gas flowing through the EGR passage 21. 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.

  FIG. 2 shows an electric circuit for spark ignition of the internal combustion engine in the present embodiment. The spark plug 12 receives spark voltage generated by the ignition coil 14 and causes spark discharge between the center electrode and the ground electrode. The ignition coil 14 is integrally incorporated in the coil case together with the igniter 13 having the semiconductor switching element 131.

  When the igniter 13 receives an ignition signal i from an ECU (Electronic Control Unit) 0 as a control device of the present embodiment, first, the semiconductor switch 131 of the igniter 13 is ignited, and a current flows to the primary side of the ignition coil 14. The semiconductor switch 131 is extinguished at the timing of the spark ignition immediately after that, and this current is cut off. Then, a self-induction action occurs, and a high voltage is generated on the primary side. Since the primary side and the secondary side share the magnetic circuit and the magnetic flux, a higher induced voltage is generated on the secondary side. The induced voltage on the secondary side reaches 10 kV to 30 kV. This high induction voltage is applied to the center electrode of the spark plug 12, and a spark discharge occurs between the center electrode and the ground electrode.

  The primary coil of the ignition coil 14 is connected to the in-vehicle power supply battery 17 via the semiconductor switch 131. When the semiconductor switch 131 is ignited and a DC voltage supplied from the battery 17 is applied to the primary side coil to start energization, the primary current flowing through the primary side (low voltage system) circuit including the primary side coil increases.

FIG. 3 illustrates the transition of the primary current after the start of energization of the primary coil. In FIG. 3, the case where the current limiting function does not work is drawn with a broken line, and the case where the current limiting function works is drawn with a one-dot chain line (the solid line will be described later). Assuming that the primary side electric circuit including the battery 17 and the primary side coil is an RL series circuit, the primary current I (t) when the DC voltage E is applied at time t = 0 is
I (t) ≈ {1-e- ^{(R / L) t} } E / R
It becomes. That is, the primary current increases as a transient phenomenon, but the rate of increase gradually decreases. When a sufficiently long time elapses, the primary current saturates to E / R as shown by the broken line in FIG.

  The igniter 13 has a current limiting function that suppresses excessive primary current. This current limiting function is similar to that of off-the-shelf igniters that are popular today. Specifically, the control circuit 132 constantly measures the primary current in the form of the voltage across the resistor 133 via the detection resistor 133. The semiconductor switch 131 is ignited while the magnitude of the primary current (voltage across the resistor 133) is equal to or less than a specified value, while the semiconductor switch 131 is extinguished when the magnitude exceeds the specified value. As a result, the primary current is clipped to the specified value as indicated by the alternate long and short dash line in FIG.

  Incidentally, the igniter 13 also has a function of forcibly cutting off the energization to the primary side coil when detecting abnormal heat generation such that the temperature of the ignition coil 14 or the igniter 13 itself exceeds the upper limit value.

  The ignition coil 14 in the present embodiment is larger than a conventional coil that can generate discharge energy much larger than the energy required at the minimum for spark ignition of the air-fuel mixture filled in the cylinder 1. It has an inductance.

  The energy of the spark discharge required for igniting the air-fuel mixture filled in the combustion chamber of the cylinder 1 is usually about 30 mJ. The conventional ignition coil is assumed to generate a spark discharge voltage by receiving electric energy of about 30 mJ exclusively. Therefore, the heat resistance limit is only enough to withstand energy of about 30 mJ to 50 mJ.

  On the other hand, in this embodiment, it is considered to increase the energy of the spark discharge as necessary, and electric energy of 100 mJ to 130 mJ at the maximum is applied to the ignition coil 14. When a large electric energy of 100 mJ is applied to a conventional ignition coil, there is a concern that it may be overheated and damaged. The ignition coil 14 in this embodiment can store much larger electric energy than that required for spark ignition of the air-fuel mixture, and even if such large electric energy is applied. It has high heat resistance so as not to cause damage due to heat generation. Of course, it is possible to avoid wasting energy by applying only a minimum amount of electrical energy necessary for spark ignition to the ignition coil 14.

In FIG. 3, the time point t ₁ is the ignition timing of the cylinder 1. At this time t ₁ , the semiconductor switch 131 of the igniter 13 associated with the cylinder 1 is extinguished, the energization of the primary coil of the ignition coil 14 associated with the cylinder 1 is cut off, and the ignition coil 14 generates The induced voltage is applied to the center electrode of the spark plug 12 of the cylinder 1.

Time t ₀ is a start time of energization of the primary coil of the ignition coil 14 in a normal state. That is, the period from time t ₀ to time t ₁ is the energization time for the primary coil of the ignition coil 14. In FIG. 3, the primary current flowing through the primary side coil in a normal state is drawn with a solid line.

In turn, the time point t ₀ ′ is a start point of energization of the primary coil of the ignition coil 14 when the electric energy for spark discharge input to the spark plug 12 is increased more than usual. That is, the period from time t ₀ ′ to time t ₁ is the energization time for the primary coil of the ignition coil 14. Since the energization start time t ₀ ′ is earlier than the normal energization start time t ₀ , the energization time in this case is longer than the normal energization time. In FIG. 3, the primary current in this case is drawn by a one-dot chain line.

As already described, the primary current flowing through the primary coil of the ignition coil 14 increases after the ignition of the semiconductor switch 131 (time t ₀ or time t ₀ ′). Accordingly, the primary current flowing through the primary coil at the ignition timing t ₁ becomes larger as the energization start time t ₀ ′ is advanced. An increase in the primary current means an increase in electrical energy applied to the ignition coil 14. As a result, the primary current is induced by the extinction of the semiconductor switch 131 (time t ₁ ) and applied to the center electrode of the ignition plug 12. This means that the induced voltage increases.

In short, as the energization start time t ₀ ′ is advanced (the primary current flowing through the primary coil at the ignition timing t ₁ is increased), the electric energy input to the spark plug 12 is increased. As a result, the voltage of the spark discharge generated between the center electrode of the spark plug 12 and the ground electrode is increased, and the duration of the spark discharge is also increased.

  Further, the ECU 0 can detect an ionic current generated in the combustion chamber of the cylinder 1 during the combustion of the fuel, and can determine the combustion state with reference to the ionic current.

  As shown in FIG. 2, in this embodiment, a circuit for detecting an ionic current is added to the electric circuit for spark ignition. This detection circuit includes a bias power supply unit 15 for effectively detecting an ionic current and an amplification unit 16 that amplifies and outputs a detection voltage corresponding to the amount of the ionic current. The bias power supply unit 15 includes a capacitor 151 that stores a bias voltage, a Zener diode 152 for increasing the voltage of the capacitor 151 to a predetermined voltage, current blocking diodes 153 and 154, and a load that outputs a voltage corresponding to the ion current. A resistor 155. The amplifying unit 16 includes a voltage amplifier 161 typified by an operational amplifier.

  The capacitor 151 is charged during arc discharge between the center electrode and the ground electrode of the spark plug 12, and then an ion current flows through the load resistor 155 by the bias voltage charged in the capacitor 151. The voltage between both ends of the resistor 155 generated by the flow of the ionic current is amplified by the amplifying unit 16 and received by the ECU 0 as the ionic current signal h.

  FIG. 4 illustrates respective transitions of the ionic current and the combustion pressure in the cylinder 1 (in-cylinder pressure) in normal combustion. In FIG. 4, the ionic current is drawn with a broken line, and the combustion pressure is drawn with a solid line. The ionic current cannot be detected during the discharge for ignition. In the case of normal combustion, the ionic current decreases by a chemical reaction before the compression top dead center after the end of spark ignition, and then increases again by thermal dissociation. In addition, the ionic current reaches a maximum almost simultaneously with the peak of the combustion pressure.

  A generator 18 serving as a power supply source for energizing the ignition coil 14, opening / closing driving of the valves 23 and 32, and an electrical system mounted on the vehicle, etc., generates engine torque from a crankshaft that is an output shaft of the internal combustion engine. The supplied power is generated and the generated power is stored in the in-vehicle power storage device 17.

  The generator 18 may be an alternator conventionally used as a generator for automobiles, or may be a motor generator having a function as an electric motor for driving a crankshaft of an internal combustion engine or an axle (and drive wheels) of a vehicle. It may be an ISG (Integrated Starter Generator). The internal combustion engine and the generator 18 are connected via, for example, a winding transmission device having a belt and a pulley as elements.

  The IC regulator or controller 181 attached to the generator 18 receives a control signal m issued from the ECU 0 and commanding a target value of the output voltage of the generator 18. Then, the semiconductor switching element is switched and applied to the excitation (field) winding so that the terminal voltage of the power storage device 17 (in other words, the power supply voltage supplied to the electrical system) follows the commanded target voltage. PWM (Pulse Width Modulation) control for adjusting the magnitude of the exciting current to be performed is performed. The output voltage of the generator 18 increases as the excitation current flowing through the excitation winding increases.

  The generator 18 that generates power is a mechanical load when viewed from the internal combustion engine. When the output voltage of the generator 18 exceeds the terminal voltage of the power storage device 17, the power storage device 17 is charged and power is supplied from the generator 18 to various electric loads of the electrical system. That is, the generator 18 works to generate electric energy by consuming energy of rotation of the crankshaft of the internal combustion engine. The amount of charge to the power storage device 17 and the amount of power supplied to the electrical load depend on the potential difference between the output voltage of the generator 18 and the terminal voltage of the power storage device 17.

  Conversely, when the output voltage of the generator 18 is less than or close to the terminal voltage of the power storage device 17, the power storage device 17 is not charged, and no power is supplied from the generator 18 to the electrical load of the electrical system (power storage). The electric load may be supplied from the device 17). That is, the generator 18 does not perform work that consumes the energy of rotation of the crankshaft of the internal combustion engine, or the work is reduced.

  In short, when a high power generation voltage is commanded from the ECU 0 to the generator 18, the mechanical load of the generator 18 with respect to engine rotation increases, and when a low power generation voltage is commanded, the mechanical load of the generator 18 with respect to engine rotation decreases.

  Further, the IC regulator or controller 181 receives a control signal m issued from the ECU 0 and commands the upper limit value of the excitation current, and detects it via the magnitude of the excitation current flowing through the excitation winding of the generator 18. Limit the excitation current to the commanded upper limit or less. More specifically, the IC regulator or controller 181 controls fDUTY, which is a DUTY ratio of the excitation current flowing through the excitation winding. The upper limit of the excitation current is intended to prevent the mechanical rotation on the internal combustion engine 100 from becoming excessive and the engine rotation from becoming unstable. Therefore, for example, the upper limit value of the excitation current is lower when the refrigerant compression compressor (not shown) of the air conditioner mounted on the vehicle is operating and when it is not operating.

  Clipping to the upper limit value of the excitation current has priority over following the target voltage value of the power generation voltage of the generator 18. That is, even if the terminal voltage of the power storage device 17 is still less than the target voltage commanded from the ECU 0, the IC regulator or controller 181 has the excitation current flowing through the excitation winding of the generator 18 at the upper limit commanded from the ECU 0. If so, do not increase the excitation current any further.

  The generator 18 performs regenerative braking when the vehicle is decelerated, and can recover the kinetic energy of the vehicle as electric energy. The ECU 0 performs excitation that flows through the excitation winding of the generator 18 when the amount of depression of the accelerator pedal by the driver becomes 0 or less than a predetermined value close to 0, that is, when deceleration of the internal combustion engine and the vehicle is requested. A control signal m for raising the upper limit value of the current and the output voltage of the generator 18 is supplied to the IC regulator or controller 181.

  The power storage device 17 is a battery (lead battery, lithium ion battery, nickel metal hydride battery, or the like), a capacitor, or the like. A plurality of types of power storage devices 17 may be combined and mounted on the vehicle.

  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 engine load), an intake air temperature in the intake passage 3 (particularly, the surge tank 33), and From an intake air temperature / intake pressure signal d output from a temperature / pressure sensor that detects intake air pressure, a sensor that detects a terminal voltage and / or terminal current (particularly, battery voltage and / or battery current) of the in-vehicle power storage device 17. The output voltage / current signal e is output from a water temperature sensor that detects the cooling water temperature indicating the temperature of the internal combustion engine. A coolant temperature signal f, a brake signal g output from a sensor (such as a brake switch or a master cylinder pressure sensor) that detects that the brake pedal is depressed or the amount of depression of the brake pedal, and an air-fuel mixture in the combustion chamber of the cylinder 1 A current signal h or the like output from a circuit for detecting an ionic current generated by the combustion of is input.

  From the output interface, the ignition signal i for the igniter 13, the fuel injection signal j for the injector 11, the opening operation signal k for the throttle valve 32, the opening operation signal l for the EGR valve 23, the generator A control signal m or the like for controlling the generator 18 is output to an IC regulator or controller 181 attached to 18.

  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, the 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 (or EGR rate) Various operating parameters such as volume). The ECU 0 applies various control signals i, j, k, l and m corresponding to the operation parameters via the output interface.

  The required value for the required EGR rate, that is, the EGR rate, which is the ratio of the EGR gas in the air-fuel mixture filled in the cylinder 1, is highest in the medium load region where the load of the internal combustion engine is medium, and the load decreases from there. It decreases, and it decreases as the load increases. The required EGR rate is 0 and the opening degree of the EGR valve 23 is also 0 in an idle operation or a low load operation region close to this, or in a high load operation region where the accelerator opening is fully open (full load) or close to full open.

  The ECU 0 of the present embodiment determines the magnitude of the electric energy input to the spark plug 12 for igniting the air-fuel mixture filled in the cylinder 1 from the current operating range of the internal combustion engine [engine speed, engine load (or The intake pressure in the surge tank 33, the intake (fresh air) amount or fuel injection amount charged into the cylinder 1)], the current temperature of the internal combustion engine (particularly, the coolant temperature), the air-fuel ratio of the mixture, etc. .

  In the memory of the ECU 0, parameters indicating the operation region of the internal combustion engine, the cooling temperature, the air-fuel ratio, etc., the magnitude of the electric energy input to the spark plug 12, in other words, the energization time to the primary coil of the ignition coil 14 Map data that defines the relationship between and is stored. The energization time of the primary coil is determined when the absolute value of the amount of change in the engine speed per unit time is not more than a predetermined value, that is, when the internal combustion engine is in a steady operation state where neither acceleration nor deceleration is performed. It is determined in advance experimentally (by testing or fitting) so that it is stable and the engine torque becomes maximum or close to maximum. The ECU 0 knows the energization time to the primary coil of the ignition coil 14 by searching the map using the current operation region of the internal combustion engine, the coolant temperature, the air-fuel ratio, and the like as keys. Further, this energization time may be corrected by the current terminal voltage (in particular, battery voltage) of the power storage device 17 that applies a voltage to the primary coil of the ignition coil 14. In this case, the energization time is extended as the terminal voltage of the power storage device 17 is lower.

  FIGS. 5 and 6 respectively show the magnitude of electric energy input to the spark plug 12 to cause spark discharge in a certain operation region [engine speed, engine load] and the fuel consumption of the internal combustion engine in the steady operation state. This schematically shows the relationship with the rate. The fuel consumption rate is the amount of fuel consumed by the internal combustion engine to travel the vehicle for a unit distance, or consumed by the internal combustion engine to supply unit horsepower (to the axle and auxiliary equipment other than the generator 18). The amount of fuel to be used. FIG. 5 shows the fuel consumption rate when the engine speed and the engine load are relatively low, and FIG. 6 shows the fuel consumption rate when the engine speed and the engine load are relatively high.

  The solid line in FIG. 5 and FIG. 6 is the fuel consumption rate that takes into account the deterioration of the fuel consumption rate caused by causing the generator 18 to generate electricity by an amount corresponding to the increase in electrical energy input to the spark plug 12. . That is, the solid line represents the fuel consumption rate in the state where the amount of power generated per unit time of the generator 18 is increased by an amount substantially equal to the amount of power per unit time currently consumed by the spark ignition system. .

  5 and 6 indicates a fuel consumption rate that does not take into account the deterioration of the fuel consumption rate caused by causing the generator 18 to generate power by an amount corresponding to the increase in electrical energy input to the spark plug 12. is there. That is, the alternate long and short dash line assumes that the amount of power generated per unit time of the generator 18 is not increased by an amount substantially equal to the amount of power per unit time currently consumed by the spark ignition system. Represents the fuel consumption rate.

W ₀ represents the electrical energy (about 30 mJ) that has been conventionally input to the spark plug 12. When the electric energy input to the spark plug 12, that is, the energy of spark discharge, is increased from the conventional value W ₀ , the combustibility of the air-fuel mixture in the cylinder 1 is improved and the cylinder 1 is extracted by heat-mechanical energy conversion. Mechanical energy increases. In other words, the engine torque output from the internal combustion engine increases. The effect of improving the heat-mechanical energy conversion efficiency due to the increase in ignition energy appears more greatly in the low load operation region, the operation region where the EGR rate is large, or the situation of lean air-fuel ratio.

However, the electrical energy that is input to the spark plug 12 is originally generated by the generator 18 that is driven by the rotation torque transmitted from the internal combustion engine. Increasing the electrical energy input to the spark plug 12 means increasing mechanical energy that the generator 18 consumes for power generation. For this reason, as shown by a solid line in FIGS. 5 and 6, the amount of mechanical energy output from the internal combustion engine by increasing the electrical energy input to the spark plug 12 increases, and the generator 18 there are W _B that the amount of mechanical energy extra spent to power the amount of increase in the electrical energy input to the spark plug 12 are balanced. The electrical energy input to the spark plug 12 aggravate rather efficiency to increase beyond W _B, thus reducing the fuel consumption performance of the vehicle.

Therefore, ECU0 is a W _B or its neighboring point corresponding to each operating region, sets the ignition energy in the operating region.

However, depending on the operating range, W _B may be approximately equal to W ₀ , ie, increase ignition energy substantially or not. For example, in a relatively high load operating region where the fuel injection amount is large, the air-fuel mixture is easily ignited in the first place, the flame propagation is good, and the heat-mechanical energy conversion efficiency by increasing the electric energy input to the spark plug 12 The improvement effect is expected to be negligible. In such an operating region, as a result, there is no clear difference between W _B and W _0, and the increase in ignition energy (W _B −W ₀ ) may be slight or zero. Alternatively, the fuel consumption rate improvement obtained by increasing the ignition energy from the initial value W ₀ (F ₀ -F _B , F ₀ '-F _B ', F ₀ -F _B 'or F ₀ ' -F _B ) Is compared with a predetermined threshold value, and it may be considered that the ignition energy is not intentionally increased from the initial value W _{0 in the} operation region where the improvement is less than the threshold value.

The efficiency of power generation by the generator 18 varies depending on the rotational speed of the generator 18 and the magnitude of torque input to the generator 18. The rotational speed of the generator 18 is proportional to the engine rotational speed. The power generation efficiency in the operation region where the engine speed and the engine load are relatively low is lower than the power generation efficiency in the operation region where the engine speed and the engine load are relatively high. When the electric energy input to the spark plug 12 is set to W _B or a point near it, the difference ΔF (= F _B −F _B ′) between the fuel consumption rate drawn by the solid line and the fuel consumption rate drawn by the alternate long and short dash line ) Becomes larger in the operation region where the engine speed and the engine load are relatively low, and becomes smaller in the operation region where the engine speed and the engine load are relatively high.

  The ECU 0 of the present embodiment sets the upper limit of the power generation rate of the generator 18 under a situation where ΔF is large compared to that under a situation where ΔF is small. The power generation rate is the ratio of the increase in power generation amount per unit time actually generated by the generator 18 to the increase in power consumption per unit time corresponding to the increase in electric energy input to the spark plug 12 ( (Increase in power generation / Increase in power consumption). As shown in FIG. 7, the ECU 0 reduces the upper limit of the power generation rate as ΔF increases, thereby suppressing the amount of power generated by the generator 18. The power generation rate of the generator 18 can be manipulated by adjusting the target output voltage of the generator 18 and / or the upper limit of the excitation current flowing through the excitation winding of the generator 18.

  In the memory of the ECU 0, map data that prescribes the relationship between parameters representing the operation region of the internal combustion engine, the cooling temperature, the air-fuel ratio, and the like and the upper limit of the power generation rate of the generator 18 is stored. The ECU 0 knows the upper limit of the power generation rate corresponding to the fuel consumption rate difference ΔF by searching the map using the current operation region of the internal combustion engine, the coolant temperature, the air-fuel ratio, and the like as keys.

In a situation where ΔF is relatively small, for example, in an operation range of medium to high rotation, medium load to high load, the fuel efficiency improvement effect obtained by increasing the ignition energy from the initial value W ₀ (F ₀ -F _B in FIG. 6). Or, F ₀ ′ −F _B ′) is small, and the required increase in ignition energy (W _B −W ₀ in FIG. 6) is relatively small (the increase in ignition energy may be zero). However, the power generation efficiency of the generator 18 is high. On the other hand, in a situation where ΔF is relatively large, for example, in an operating range of low to medium rotation, low load to medium load, the fuel efficiency improvement effect obtained by increasing the ignition energy from the initial value W ₀ (F ₀ in FIG. 5). −F _B or F ₀ ′ −F _B ′) is large, and the required increase in ignition energy (W _B −W ₀ in FIG. 5) is larger than the former operating range, but the power generation efficiency of the generator 18 is Lower than the driving range.

  The ECU 0 suppresses power generation by the generator 18 by lowering the upper limit of the power generation rate in the latter operation region where the power generation efficiency is low than in the former operation region. In a specific operation region, the upper limit of the power generation rate may be 0, that is, power generation may not be performed.

  On the other hand, in the former operation region where the power generation efficiency is high, the power generation by the generator 18 is promoted by raising the upper limit of the power generation rate, and the overall efficiency is optimized. The power generation rate may be raised higher than 100%.

As a result, the electrical energy input to the spark plug 12 in the latter region (the effect of improving the fuel efficiency due to the increase in ignition energy) is higher than the region in the former. Is lower than the electric energy input to the spark plug 12 in the former operation region, and the output voltage or power generation amount of the generator 18 in the latter operation region is higher than the output of the generator 18 in the former operation region. It will be lower than the voltage or power generation. By reducing the power generation rate, the fuel consumption rate of the internal combustion engine in the latter operating region approaches from F _B on the solid line shown in FIG. 5 to F _B ′ on the one-dot chain line.

  Note that if the upper limit of the power generation rate of the generator 18 is set low in a region where ΔF is large, the amount of power generated per unit time of the generator 18 is insufficient with respect to the power consumption per unit time in the region. Although the shortage of electric power is covered by the electric charge stored in the power storage device 17, at least a part of the electric charge is recovered by regenerative braking when the vehicle is decelerated in the past.

In the present embodiment, a spark ignition internal combustion engine that causes spark discharge between the electrodes of the spark plug 12 installed in the cylinder 1 to ignite the air-fuel mixture in the cylinder 1, and is supplied with rotational torque from the internal combustion engine. A vehicle control device 0 on which a generator 18 for generating electricity is mounted, which increases the magnitude of electric energy input to the spark plug 12 in accordance with the operating region of the internal combustion engine and does not involve power generation by the generator 18. The fuel consumption rate F _B obtained by increasing the electric energy input to the spark plug 12 and the increase in electric energy (W _B −W ₀ ) input to the spark plug 12 to the generator 18 by an amount corresponding to the increase (W _B −W ₀ ). When the difference ΔF from the fuel consumption rate F _B ′ caused by the power generation is large, the actual power generation increment of the generator 18 and the input to the spark plug 12 are compared with the case where the difference ΔF is small. The upper limit to be set for the power generation rate, which is a ratio to the increase in power generation necessary to compensate for the increase in electric energy (W _B −W ₀ ) to be reduced, is reduced, and the power generation that is insufficient is reduced. The control device 0 is configured to compensate by regenerative braking at the time.

In addition, in the present embodiment, a spark ignition internal combustion engine that causes spark discharge between the electrodes of the spark plug 12 installed in the cylinder 1 to ignite the air-fuel mixture in the cylinder 1, and rotational torque is supplied from the internal combustion engine. receiving the generator 18 for generating electricity is an control apparatus 0 for a vehicle to be mounted, improved worth of fuel consumption obtained by increasing the predetermined value W ₀ in the electrical energy input to the spark plug 12 (F ₀ -F _B , F ₀ '-F _B ', F ₀ -F _B 'or F ₀ ' -F _B ), in the operating region, the improvement (F ₀ -F _B , F ₀ '-F _B ', Compared with the operation region in which F ₀ −F _B ′ or F ₀ ′ −F _B ) is small, the electric energy input to the spark plug 12 is further increased from the predetermined value W ₀ , and the actual generator 18 the amount of increase in the electric energy entering the power generation amount of the increment and the ignition plug 12 (W _B - ₀₎ as well as lower limit to be set for the power factor of the ratio of the power generation amount of increment necessary to compensate for, configure the controller 0 to compensate for the power generation amount is insufficient by regenerative braking during deceleration of the vehicle did.

That is, when the increase in electric energy (W _B −W ₀ ) input to the spark plug 12 is large, the increase in electric energy (W _B −W ₀ ) input to the spark plug 12 is small. The upper limit of the power generation rate is lower. Further, in the operating region where the power generation efficiency of the generator 18 is high, the electric energy input to the spark plug 12 is increased from its initial value W ₀ (W _B −W ₀ ) compared to the operating region where the power generation efficiency is poor. (The increase amount may be set to 0 depending on the operation region).

  According to the present embodiment, in a situation where the ignitability of the air-fuel mixture and the improvement effect of the thermal-mechanical energy conversion efficiency can be expected, the electrical energy input to the spark plug 12, in other words, the spark discharge energy is increased. The air-fuel mixture filled in the cylinder 1 is stably ignited and burned. The amount of electric power consumed as the electric energy input to the spark plug 12 is increased is generated in an operating region where the power generation efficiency of the generator 18 is high, and is generated and recovered by regenerative braking. Accordingly, it is possible to realize the improvement of the overall fuel consumption performance of the internal combustion engine as well as the stabilization of the ignition combustion of the air-fuel mixture and the improvement of the drivability.

  The present invention is not limited to the embodiment described in detail above. For example, the upper limit set for the power generation rate of the generator 18 is adjusted according to the current power storage amount of the power storage device (particularly, battery) 17, in other words, the terminal voltage (battery voltage) of the power storage device 17. Also good. Even in a low / medium speed, low / medium load operating region where ΔF is large, when the amount of power stored in the power storage device 17 is decreasing and the terminal voltage of the power storage device 17 is decreasing, the amount of decrease is It is preferable to suppress the overdischarge of the power storage device 17 and maintain the power storage amount by raising the upper limit for the power generation amount of the generator 18 as the value increases.

Further, a threshold value as a condition for determining whether or not the electric energy input to the spark plug 12 is increased from its initial value W ₀ , that is, an improvement in the fuel consumption rate obtained by increasing the ignition energy from the initial value W ₀ ( F ₀ -F _B , F ₀ '-F _B ', F ₀ -F _B 'or F ₀ ' -F _B ) may be made variable according to the operating range of the internal combustion engine. Specifically, in the operation region where the power generation efficiency of the generator 18 is high, the threshold value is made larger than in the operation region where the power generation efficiency is poor so that the ignition energy is less likely to increase (instead, focusing on power generation and charging). Is possible).

  The magnitude of the electrical energy input to the spark plug 12 installed in each of the plurality of cylinders 1 included in the internal combustion engine may be equal for each cylinder 1 or may be different for each cylinder 1.

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

  The present invention can be applied to control of a spark ignition internal combustion engine mounted on a vehicle and a generator associated with the internal combustion engine.

0 ... Control unit (ECU)
DESCRIPTION OF SYMBOLS 1 ... Cylinder 11 ... Injector 12 ... Spark plug 13 ... Igniter 14 ... Ignition coil 17 ... Power storage device (battery and / or capacitor)
18 ... Generator b ... Crank angle signal c ... Accelerator opening signal i ... Ignition signal m ... Control signal

Claims (2)

A spark ignition type internal combustion engine that causes spark discharge between spark plug electrodes installed in a cylinder to ignite an air-fuel mixture in the cylinder, and a generator that generates electric power by receiving rotational torque from the internal combustion engine are mounted. A control device for a vehicle,
While increasing the magnitude of the electrical energy input to the spark plug according to the operating region of the internal combustion engine,
The fuel consumption rate obtained without power generation by the generator and the fuel consumption rate that takes into account the deterioration of the fuel consumption rate caused by causing the generator to generate electricity by an amount corresponding to the electrical energy input to the spark plug When the difference is large, this is the ratio between the actual power generation increment of the generator and the power generation increment required to compensate for the increase in electrical energy input to the spark plug, compared to the case where the difference is small. A control device that lowers the upper limit set for the power generation rate and compensates for the insufficient power generation amount by regenerative braking during deceleration of the vehicle. A spark ignition type internal combustion engine that causes spark discharge between spark plug electrodes installed in a cylinder to ignite an air-fuel mixture in the cylinder, and a generator that generates electric power by receiving rotational torque from the internal combustion engine are mounted. A control device for a vehicle,
In the operation region where the improvement in the fuel consumption rate obtained by increasing the electric energy input to the spark plug from a certain predetermined value is large, the electric energy input to the spark plug is smaller than in the operation region where the improvement is small. With respect to the power generation rate that is a ratio between the increase in the power generation amount of the actual generator and the increase in the power generation amount necessary to make up for the increase in the electric energy input to the spark plug, which is further increased from the predetermined value. A control device that lowers the upper limit to be set and compensates for insufficient power generation by regenerative braking when the vehicle is decelerated.

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