Determination device for spark ignition internal combustion engine

Abstract

To provide means which can easily inspect whether or not a spark discharge is properly generated in an ignitor of a spark ignition type internal combustion engine.SOLUTION: A determination device is related to a spark ignition type internal combustion engine for evoking a spark discharge by applying a high voltage induced at a secondary-side coil to an electrode of an ignition plug by carrying electricity to a primary-side coil of an ignition coil, and blocking the electricity-carrying, measures a primary current flowing through the primary-side coil at timing immediately after the block of the electricity-carrying to the primary-side coil or a primary voltage applied to the primary-side coil, and determines that whether or not the proper spark discharge is generated at the ignition plug on the basis of the measured primary current or primary voltage, .SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an apparatus for determining whether or not proper spark discharge occurs in a spark plug installed in a cylinder of a spark ignition internal combustion engine.

Background Art

[0002] In a spark ignition internal combustion engine mounted on a vehicle or the like, a spark plug for igniting an air-fuel mixture filled in a cylinder receives an induced voltage generated by an ignition coil and causes a discharge due to dielectric breakdown between a center electrode and a ground electrode.

[0003] An igniter having a semiconductor switching element is provided on an electric circuit for energizing the ignition coil. When the semiconductor switch of the igniter is arced (set to the ON state (conductive state)), current flows through the primary coil of the ignition coil. The primary current flowing through the primary coil increases while the semiconductor switch is arced. Then, when the semiconductor switch is extinguished (set to the OFF state (non-conductive state)) at the appropriate spark ignition timing, the primary current is interrupted, and a high voltage is generated in the primary coil of the ignition coil due to self-induction at that moment. Consequently, an even higher induced voltage is generated in the secondary coil that shares the magnetic circuit and magnetic flux with the primary coil. When this high induced voltage is applied to the center electrode of the spark plug, a discharge occurs between the center electrode and the ground electrode (see, for example, the following patent document).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The object of the present invention is to provide a means for simply inspecting whether or not a proper spark discharge occurs in this type of spark ignition device.

Means for Solving the Problems

[0006] The present invention relates to a spark ignition internal combustion engine that causes a spark discharge by applying a high voltage induced in a secondary coil to the electrodes of a spark plug by energizing and then interrupting the energization of a primary coil of an ignition coil. A determination device is configured to measure a primary current flowing through the primary coil or a primary voltage applied to the primary coil at a time immediately after the energization of the primary coil is interrupted, and to determine whether or not a proper spark discharge has occurred in the spark plug based on the measured primary current or primary voltage.

[0007] More specifically, Time point T when the energization of the primary coil is cut off 0 From that point, if normal spark discharge occurs, it is experimentally confirmed that a characteristic vibration appears in the waveform of the primary current or primary voltage. Set the time point T at the end of the period during which this occurs 1 Calculate the time integral value of the primary current or primary voltage during the period up to this time point T. If the time integral value exceeds the determination threshold value, it is determined that proper spark discharge has occurred at the spark plug. If it does not exceed, it is determined that proper spark discharge has not occurred 。

[0008] Unlike the present invention, it is not impossible to measure a secondary current flowing through a secondary coil directly connected to a spark plug or a secondary voltage generated in the secondary coil. However, the secondary voltage reaches 20 kV to 40 kV. In order to detect such an extremely high voltage and a small current, it is necessary to incorporate a large-sized measuring device or circuit, which is actually difficult. However, the method of the present invention can avoid such difficulties.

Advantages of the Invention

[0009] According to the present invention, it is possible to simply inspect whether or not a proper spark discharge occurs in the ignition device of a spark ignition internal combustion engine.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0011] An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an overview of an internal combustion engine for a vehicle in this embodiment. The internal combustion engine in this embodiment is a spark ignition type four-stroke gasoline engine and includes a plurality of cylinders 1 (for example, three cylinders). One of them is illustrated in FIG. 1. An injector 11 for injecting fuel toward the intake port is provided in the vicinity of the intake port connected to each cylinder 1, upstream of the intake valve of each cylinder 1.

[0012] Further, a spark plug 12 is attached to the ceiling portion of the combustion chamber of each cylinder 1. The spark plug 12 receives the application of the induced voltage generated by the ignition coil 14 and causes a spark discharge between the center electrode and the ground electrode. The ignition coil 14 is integrally built into the coil case together with an igniter 13 which is a semiconductor switching element.

[0013] An intake passage 3 for supplying intake air to the cylinder 1 takes in air from the outside and guides it to the intake port of each cylinder 1. An air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged on the intake passage 3 in this order from upstream.

[0014] An exhaust passage 4 for discharging exhaust from the cylinder 1 guides the exhaust generated by burning fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42 and a three-way catalyst 41 for exhaust purification are arranged on this exhaust passage 4.

[0015] The exhaust gas recirculation (EGR) device 2 includes an external EGR passage 21 that connects the exhaust passage 4 and the intake passage 3, 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 the EGR gas flowing through the EGR passage 21. The inlet of the EGR passage 21 is connected to a predetermined location downstream of the catalyst 41 in the exhaust passage 4, for example. The outlet of the EGR passage 21 is connected to a predetermined location (particularly, the surge tank 33) downstream of the throttle valve 32 in the intake passage 3, for example.

[0016] The (Electronic Control Unit) 0 that controls the operation of the internal combustion engine of the present embodiment is a microcomputer system having a processor, a memory, an input interface, an output interface, etc. The ECU 0 may be such that a plurality of ECUs or controllers are communicably connected to each other via an electric communication line such as a CAN (Controller Area Network).

[0017] The input interface of the ECU 0 receives 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 a crank angle sensor that detects the rotation angle and engine speed of the crankshaft of the internal combustion engine, an accelerator opening signal c output from a sensor that detects the depression amount of the accelerator pedal or the opening degree of the throttle valve 32 as the accelerator opening (so-called, the required engine load rate or engine torque), a coolant water temperature signal d output from a coolant water temperature sensor that detects the coolant water temperature of the internal combustion engine, an intake air temperature·intake air pressure signal e output from a temperature·pressure sensor that detects the intake air temperature and intake air pressure in the intake passage 3 (particularly, the surge tank 33), a brake signal f 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 depression amount of the brake pedal, a cam angle signal g output from a cam angle sensor at a plurality of cam angles of the intake camshaft of the internal combustion engine, an atmospheric pressure signal h output from an atmospheric pressure sensor that detects the atmospheric pressure, etc.

[0018] From the output interface of ECU0, an ignition signal i is output to the igniter 13 of the spark ignition device, a fuel injection (valve opening) signal j is output to the injector 11, a throttle valve opening operation signal k is output to the throttle valve 32, a throttle valve opening operation signal l is output to the EGR valve 23, and so on.

[0019] The processor of ECU0 interprets and executes a program pre-stored in the memory, calculates operating parameters, and controls the operation of the internal combustion engine. ECU0 acquires various types of information a, b, c, d, e, f, g, h necessary for the operation control of the internal combustion engine through the input interface, and knows the current operating region of the internal combustion engine [engine speed, accelerator opening (or intake pressure in the surge tank 33, amount of air (fresh air) inhaled into cylinder 1)]. Then, various operating parameters such as the required fuel injection amount corresponding to the intake air amount (necessary to realize the target air-fuel ratio), fuel injection timing (including the number of fuel injections for one combustion), fuel injection pressure, ignition timing (including the number of ignitions for one combustion), required EGR rate (or EGR gas amount), etc., are determined. ECU0 applies various control signals i, j, k, l corresponding to the operating parameters through the output interface.

[0020] Fig. 2 shows the electric circuit of the spark ignition device of the present embodiment. As already described, the internal combustion engine of the present embodiment includes a plurality of cylinders 1. What is shown in Fig. 2 is the electric circuit of the spark ignition device corresponding to one cylinder 1. Therefore, the spark plug 12, the igniter 13, and the ignition coil 14 are individual for each cylinder 1, and the number thereof is the same as the number of cylinders 1 of the internal combustion engine.

[0021] For each ignition coil 14 that supplies a high voltage for spark ignition to the spark plug 12 installed in each cylinder 1, the primary coil 141 and the secondary coil 142 form a pair. The primary coil 141 is connected to the in-vehicle power storage device 16 via the semiconductor switch 13 of the igniter. The semiconductor switch 13 is, for example, a power transistor, an IGBT (Insulated Gate Bipolar Transistor), or the like. The power storage device 16 is a battery (lead battery, lithium ion battery, nickel metal hydride battery, etc.), a capacitor, or the like. The noise prevention diode 15 interposed between the primary coil 141 and the secondary coil 142 prevents reverse current from flowing from the secondary side 142 to the primary side 141.

[0022] When the igniter attached to the ignition coil 14 receives the ignition signal i from the ECU0, first, the semiconductor switch 13 arcs, and the DC voltage supplied from the power storage device 16 is applied to the primary coil 141 of the ignition coil 14, starting the energization of the primary coil 141. Assuming that the primary electrical circuit including the power storage device 16 and the primary coil 141 is an RL series circuit, when the DC voltage E is applied at t = 0, the primary current I(t) flowing through the primary coil 141 is I(t)≒{1 - e -(R / L)t}E / R That is, as a transient phenomenon, the primary current I(t) increases (however, after a certain amount of time has elapsed since the start of energization, the rate of increase decreases, and finally the primary current I(t) saturates at E / R).

[0023] When the primary current becomes sufficiently large, the ECU0 extinguishes the arc of the semiconductor switch 13 in accordance with the ignition timing for the air-fuel mixture filled in the cylinder 1, thereby cutting off the energization of the primary coil 141. Then, self-induction occurs, and a high voltage is generated in the primary coil 141. Since the primary coil 141 and the secondary coil 142 of the ignition coil 14 share a magnetic circuit and magnetic flux, an even higher induced voltage is generated in the secondary coil 142. The high induced voltage is applied to the center electrode of the spark plug 12, and a discharge due to dielectric breakdown occurs between the center electrode and the ground electrode.

[0024] Furthermore, in the present embodiment, immediately after the energization of the primary coil 141 of the ignition coil 14 is interrupted, the primary current flowing through the primary coil 141 or the primary voltage applied to the primary coil 141 is measured, and based on the measured primary current or primary voltage, it is determined whether or not proper spark discharge has occurred in the spark plug 12.

[0025] FIG. 3 illustrates the transition of the fluctuation of the primary current flowing through the primary coil 141 of the spark ignition device associated with the cylinder 1. In FIG. 3, the solid line depicts an example of the primary current measured when proper spark discharge has occurred at the spark plug 12, and the dashed line depicts an example of the primary current measured when proper spark discharge has not occurred at the spark plug 12.

[0026] In FIG. 3, T0 is the time point when the energization of the primary coil is interrupted. When proper spark discharge has occurred at the spark plug 12, as represented by the solid line, the primary current vibrates greatly up and down immediately after the time point T0. On the other hand, when proper spark discharge has not occurred at the spark plug 12, as represented by the dashed line, the obvious up and down movement of the primary current as in the former case does not occur immediately after the time point T0.

[0027] Thus, depending on whether or not proper spark discharge has occurred at the spark plug 12, the waveform of the primary current or primary voltage immediately after the energization of the primary coil 141 is interrupted may differ. In view of the above, in the present embodiment, the primary current or primary voltage is repeatedly measured actually at a constant short period, and based on the time series of the primary current value or primary voltage value, it is determined whether or not proper spark discharge has occurred.

[0028] As shown in FIG. 2, the determination device 5 of the present embodiment is connected to a line connecting the ECU 0 and the primary coil 141 of the ignition coil 14, and measures the primary current or primary voltage on that line (that is, constantly measures the primary current or primary voltage of the primary coil 141 of the ignition coil 14 for each cylinder 1), and a measurement unit 51 that enables this, and a determination unit 52 that determines whether or not a discharge has occurred between the electrodes of the spark plug 12 connected to the secondary coil 142 of the ignition coil 14 based on the primary current or primary voltage measured via the measurement unit 51.

[0029] The measurement unit 51 (the circuit that becomes it) may be pre-mounted on the spark ignition device of the internal combustion engine, or may be connected retroactively to the line connected to the primary coil 141 of the spark ignition device (such as during an inspection to confirm whether the spark discharge in the spark plug 12 is properly executed).

[0030] The determination unit 52 is a microcomputer system having a processor, a memory, an input interface, an output interface, etc. The processor of the determination unit 52 interprets and executes a program stored in the memory in advance, and determines whether or not a spark discharge has properly occurred at the spark plug 12 based on the time series of the primary current value or primary voltage value acquired via the measurement unit 51. The determination unit 52 may be pre-mounted on the spark ignition device of the internal combustion engine, or may be connected retroactively to the line connected to the primary coil 141 of the spark ignition device.

[0031] Of course, the ECU 0 that controls the internal combustion engine can take on the function of the determination unit 52. In this case, the ECU 0 serving as the determination unit 52 receives the primary current value or primary voltage value measured via the measurement unit 51, and the ECU 0 determines whether or not a spark discharge has properly occurred at the spark plug 12 mainly.

[0032] The determination unit 52 may be a known external diagnostic tool (also called a scan tool or service tool). Recent ECUs 0 are equipped with a function as an on-board diagnostics, and when detecting a defect, disconnection of various sensors, or any abnormality in the internal combustion engine, information regarding the abnormality can be recorded. The information may include the time series of the primary current value or primary voltage value of the primary coil 141. The external diagnostic tool can be communicably connected to the ECU 0 by wire (connecting a cable (coupler) to a diagnostic connector (OBD connector) mounted on the vehicle) or wirelessly, and read the information stored and held by the ECU 0. Then, with reference to the time series of the primary current value or primary voltage value included therein, it is determined whether a spark discharge has appropriately occurred at the spark plug 12.

[0033] The measurement unit 51 and the determination unit 52 may be integrated into one device. The device functioning as the determination device 5 may be detachable from the spark ignition device of the vehicle or the internal combustion engine like a known external diagnostic tool, or may be installed so as not to be detached from the vehicle or the spark ignition device.

[0034] The determination unit 52, for example, calculates the time integral value of the primary current or primary voltage in the period immediately after the time point T0 when the energization to the primary coil 141 is cut off, in other words, the integrated value of the time series of the primary current value or primary time voltage value repeatedly measured at a constant period by the measurement unit 51, compares the time integral value with a determination threshold value A, and determines whether an appropriate spark discharge has occurred at the spark plug 12. As respectively shown by the solid line and the broken line in FIG. 3, between the case where an appropriate spark discharge has occurred at the spark plug 12 and the case where an appropriate spark discharge has not occurred, there is a difference in the primary current or primary voltage during the period from the time point T0 when the energization to the primary coil 141 is cut off to a predetermined time point T1. to A difference occurs 。The determination unit 52 calculates the time integral value during a predetermined period from time point T0 to time point T1. If the time integral value exceeds the determination threshold A, it determines that a proper spark discharge has occurred at the spark plug 12; if it does not exceed, it determines that a proper spark discharge has not occurred. Here, the time point T1 is set to the end of a period where it has been experimentally confirmed that if a normal spark discharge occurs, vibrations characteristic of the waveform of the primary current or primary voltage will appear.

[0035] In addition to comparing the time integral value of the primary current or primary voltage during a predetermined period with the determination threshold A, the determination unit 52 processes the waveform of the primary current or primary voltage, that is, the time series of the measured values, during a predetermined period from time point T0 to time point T1 measured via the measurement unit 51 with a frequency filter that allows components in a specific frequency band to pass through and attenuates or blocks components in other frequency bands, and determines whether a proper spark discharge has occurred at the spark plug 12 by comparing the maximum value, minimum value, or time integral value of the components processed by the frequency filter with the determination threshold.

[0036] Alternatively, the determination unit 52 determines whether a proper spark discharge has occurred at the spark plug 12 by determining whether vibrations characteristic (having a specific frequency band and / or amplitude) of the waveform of the primary current or primary voltage appear during a predetermined period from time point T0 to time point T1, or by comparing the length of the elapsed time until characteristic vibrations appear after time point T0 with the determination threshold.

[0037] In the present embodiment, it relates to a spark ignition internal combustion engine that applies a high voltage induced in the secondary coil 142 to the electrodes of the spark plug 12 by energizing and then interrupting the energization of the primary coil 141 of the ignition coil 14 to cause a spark discharge. A determination device 5 is configured to measure the primary current flowing through the primary coil 141 or the primary voltage applied to the primary coil 141 at a time immediately after interrupting the energization of the primary coil 141 (during a predetermined period from time point T0 to time point T1), and determine whether a proper spark discharge has occurred at the spark plug 12 based on the measured primary current or primary voltage.

[0038] In particular, in the present embodiment, the primary current flowing through the primary coil 141 or the primary voltage applied to the primary coil 141 at a time immediately after the energization of the primary coil 141 is interrupted is measured, and whether or not a proper spark discharge has occurred in the spark plug 12 is determined by comparing the time integral value of the measured primary current or primary voltage with a determination threshold value A. [[ID=​1]] [[ID=​2]]

[0039] [[ID=​3]] [[ID=​4]]According to the determination device 5 of the present embodiment, it is possible to simply inspect whether or not a proper spark discharge occurs in the ignition device of the spark ignition internal combustion engine. [[ID=​5]] [[ID=​6]]

[0040] [[ID=​7]] [[ID=​8]]Note that the present invention is not limited to the embodiments described in detail above. Various modifications are possible for the specific configurations of each part, the processing procedures, etc., without departing from the spirit of the present invention. [[ID=​9]] [[ID=​10]]

Description of Reference Numerals

[0041] [[ID=​14]] [[ID=​15]]12…Spark plug [[ID=​16]] [[ID=​17]]14…Ignition coil [[ID=​18]] [[ID=​19]]141…Primary coil [[ID=​20]] [[ID=​21]]142…Secondary coil [[ID=​22]] [[ID=​23]]5…Determination device [[ID=​24]] [[ID=​25]]i…Ignition signal

Claims

【Claim 1】 A spark ignition internal combustion engine that applies a high voltage induced in a secondary coil to an electrode of a spark plug by energizing and then interrupting energization of a primary coil of an ignition coil to cause a spark discharge. It measures a primary current flowing through the primary coil or a primary voltage applied to the primary coil at a time immediately after interruption of energization to the primary coil, and determines whether or not proper spark discharge has occurred in the spark plug based on the measured primary current or primary voltage. A determination device that calculates a time integral value of a primary current or a primary voltage during a period from a time point T0 when energization to the primary coil is interrupted to a time point T1 set at the end of a period experimentally confirmed that if normal spark discharge occurs, a characteristic vibration appears in the waveform of the primary current or the primary voltage, and determines that proper spark discharge has occurred at the spark plug if the time integral value exceeds a determination threshold, and determines that proper spark discharge has not occurred if it does not exceed.

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