JP2011058376A - Method for controlling glow plug of internal combustion engine, and internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for controlling the glow plug of an internal combustion engine and the internal combustion engine, improving the exhaust gas performance of the internal combustion engine. <P>SOLUTION: The duty ratio of the control signals of the glow plugs 7a-7d of cylinders 4a-4d are set according to a difference between target ignition timing set so that the exhaust gas performance is optimized with respect to the cylinders 4a-4d of the engine 1 and actually measured ignition timing detected by sensors 9a-9d with respect to the cylinders 4a-4d, and the amount of power distributed to each of the glow plugs 7a-7d is controlled. Thereby, the combustion state of each of the cylinders 4a-4d is improved in the exhaust gas performance. Accordingly, the exhaust gas performance of the engine 1 is improved. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an internal combustion engine blow plug control method and an internal combustion engine, and more particularly to an internal combustion engine glow plug control method and an internal combustion engine capable of improving exhaust gas performance of the internal combustion engine.

  In general, a diesel engine is provided with a glow plug that preheats a combustion region and assists ignition by causing a current to flow through a coil or a rod built in the spark plug to cause red heat to improve startability. Normally, when the ignition switch of a diesel engine is turned on, a current (hereinafter referred to as a glow current) flows through the glow plug, and the current supply is stopped after a certain period of time. In particular, hydrocarbons (HC) and carbon monoxide (CO) For example, there is an example (afterglow) in which the glow current continues to flow for a certain period even when the fuel is expected to be stably combusted after starting the diesel engine.

  At this time, when there is a slight difference in condition (combustion caused by fuel injection, intake air, etc.) due to differences in individual fuel injection nozzles or actual piston compression ratios in each cylinder. In some cylinders, combustion is slow, and in some cylinders, combustion is active. FIG. 8 is a graph showing in-cylinder pressure (heat generation rate) measured during cryogenic operation with an in-cylinder pressure sensor attached to each cylinder. As shown in this result, it can be seen that the combustion state of each cylinder is clearly different, such that the ignition timing is early in the cylinder C1 and the ignition timing is late in the cylinder C2.

  However, when the combustion state is different for each cylinder in this way, there is a problem that the exhaust gas performance at the time of starting the engine varies. The original purpose of the glow plug is to assist slow combustion, and it is not necessary to control the conventional glow plug in spite of the fact that no glow current needs to flow through the glow plug of the cylinder that is actively burning. The glow current continues to flow in the same manner for all cylinders. For this reason, a glow current also flows through a glow plug of a cylinder in which the combustion state is active, so that there is a problem that wasteful power is consumed and the fuel consumption rate increases accordingly.

  As a method for controlling the glow plug, a method for controlling the energization amount of the glow plug according to the position of the piston when the vehicle is stopped (see, for example, Patent Document 1), and energization of the glow plug according to the engine temperature and the rotational speed. A method for controlling the amount (see, for example, Patent Document 2), a first control value of the glow plug supply power with the glow plug as a target temperature, and a second control value of the glow plug supply power corresponding to the operating state, and these A method for controlling the power supply to the glow plug according to the comparison result (for example, see Patent Document 3), a method for controlling the energization to the glow plug according to the fuel injection amount (for example, see Patent Document 4), etc. There is.

JP 2004-176469 A JP-A-6-108960 Japanese Patent Laid-Open No. 8-312515 JP 2008-106612 A

  An object of the present invention is to provide a glow plug control method for an internal combustion engine and an internal combustion engine that can improve the exhaust gas performance of the internal combustion engine.

  In order to achieve the above object, a glow plug control method for an internal combustion engine according to the present invention applies heat to a glow plug provided in each of a plurality of cylinders when the internal combustion engine is started to apply heat to a combustion region of each cylinder. In the glow plug control method for an internal combustion engine that assists ignition, the energization amount to the glow plug is set so that actual ignition is performed at a target ignition timing that is preset so as to be optimal in terms of exhaust gas performance for each cylinder. Is controlled for each cylinder.

  In the glow plug control method for an internal combustion engine, the energization amount to the glow plug is set for each cylinder according to a difference between the actually measured ignition timing detected for each cylinder and the target ignition timing for each cylinder. To control.

  Further, in the glow plug control method for an internal combustion engine, the temperature of the glow plug is increased by increasing a duty ratio of a glow current to the glow plug according to a delay of the measured ignition timing with respect to the target ignition timing, When the mounting ignition timing is not delayed with respect to the target ignition timing, the duty ratio of the current flowing through the glow plug is set to zero, and control is performed so that no current flows through the glow plug.

  This makes it possible to cause combustion at the target ignition timing by increasing the energization amount to the glow plug so that combustion is likely to occur in a slow-combustion cylinder, and to reduce the energization amount to the glow plug in a cylinder where combustion is active. Lowering power consumption can be reduced.

  In the above-described glow plug control method for an internal combustion engine, the target ignition timing is created using map data in which the engine speed, the fuel injection amount, and the environmental correction term are variables.

  As a result, the target ignition position can be set according to, for example, operating conditions and environmental conditions (cooling water temperature, atmospheric pressure, temperature, etc.), so that the setting accuracy of the target ignition timing can be improved. Therefore, the energization control of each glow plug can be performed more appropriately. Therefore, the exhaust gas performance of each cylinder can be further improved, and the exhaust gas performance of the internal combustion engine can be further improved.

  Further, the internal combustion engine of the present invention for achieving the above-mentioned object is ignited by applying heat to the glow plugs provided in each of the plurality of cylinders when the internal combustion engine is started to apply heat to the combustion regions of the respective cylinders. An internal combustion engine having an auxiliary glow plug control device includes detection means for detecting an actual ignition timing for each cylinder, an actual ignition timing detected for each cylinder by the detection means, and exhaust gas for each cylinder. The control unit is configured to control the energization amount to the glow plug for each cylinder according to a difference from a target ignition timing set in advance so as to be optimal in terms of performance.

  According to the glow plug control method and internal combustion engine of an internal combustion engine of the present invention, when the internal combustion engine is started, the energization amount to the glow plug is such that actual ignition is performed at each target ignition timing of each of the plurality of cylinders of the internal combustion engine. By controlling for each cylinder, the combustion state of each cylinder can be made better in terms of exhaust gas performance, so that the exhaust gas performance of the internal combustion engine can be improved.

It is a principal part block diagram of the internal combustion engine of embodiment of this invention. FIG. 2 is a stroke diagram of a glow plug control method for the internal combustion engine of FIG. 1. It is a wave form diagram of the example of a signal detected by the sensor of each cylinder of the internal-combustion engine of Drawing 1. It is a wave form diagram of the example of a signal detected by the sensor of each cylinder of the internal-combustion engine of Drawing 1. It is a wave form chart of the example of a signal detected by the sensor of each cylinder at the time of performing the glow plug control method of the internal-combustion engine of an embodiment of the invention. It is a graph which shows the exhaust gas performance at the time of performing the glow plug control method of the internal combustion engine of embodiment of this invention. It is the graph which compared and showed the electric power used when the glow plug control method of the internal combustion engine of embodiment of this invention is performed, and the case where it is not performed. It is a graph which shows the cylinder pressure (heat generation rate) in each cylinder of the conventional internal combustion engine. It is a wave form diagram of the signal detected by the sensor of each cylinder when not performing glow control itself. It is a graph which shows the exhaust gas performance in the case of FIG. It is a wave form diagram of the signal detected by the sensor of each cylinder at the time of performing the conventional glow plug control method. It is a graph which shows the exhaust gas performance in the case of FIG.

  Hereinafter, an internal combustion engine according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a configuration diagram of a main part of the internal combustion engine of the present embodiment. The internal combustion engine of the present embodiment is configured as an in-line four-cylinder common rail type diesel engine (hereinafter simply referred to as an engine) 1 mounted on an automobile such as a truck, for example, and includes an engine block (engine body) 2 and a glow And a plug control device 3.

  In the engine block 2, for example, four cylinders 4a to 4d are installed. In each of the cylinders 4a to 4d, a piston (not shown) and a nozzle of a fuel injection device are installed. This piston is installed in a state in which it can reciprocate along the longitudinal direction of the cylinders 4a to 4d. Further, the nozzle of the fuel injection device is installed at a position facing the piston top surface in a state where a part thereof faces each combustion chamber (combustion region) of each cylinder 4a to 4d.

  In each combustion chamber of each cylinder 4a to 4d, fuel is supplied from the nozzle of the fuel injection device to the compressed and heated air to cause self-ignition, and each cylinder 4a is caused by the expansion gas generated by combustion by self-ignition at this time. Each piston in -4d is driven.

  An intake manifold 5 is connected to the intake ports of the cylinders 4a to 4d. Although not shown, the intake manifold 5 is connected to the outlet of the compressor of the supercharger through an intake pipe. On the other hand, an exhaust manifold 6 is connected to the exhaust ports of the cylinders 4a to 4d. Although not shown, the exhaust manifold 6 is connected to an inlet of a turbocharger turbine through an exhaust pipe.

  The glow plug control device 3 of the engine 1 combusts the cylinders 4a to 4d by energizing the glow plugs 7a to 7d provided in each of the plurality of cylinders 4a to 4d when the engine 1 is started (particularly when cold). A device for assisting ignition by applying heat to the chamber, for example, four glow plugs 7a to 7d, a relay circuit 8, for example, four sensors (detection means) 9a to 9d, a glow controller (control unit) 10, have.

  The glow plugs 7a to 7d are components that assist the ignition by directly heating the air in the combustion chambers of the cylinders 4a to 4d when the engine 1 is started, and the heat generating parts of the glow plugs 7a to 7d are each cylinder 4a. It is attached to the engine block 2 so as to face the combustion chamber of 4d.

  As the glow plugs 7a to 7d, for example, ceramic type glow plugs are used. A ceramic glow plug has a structure in which a heater element is embedded in ceramics (for example, silicon nitride), and is excellent in heat resistance and durability. By using a ceramic-type glow plug, the temperature can be raised more quickly than when a metal-type glow plug is used, so the preheating time can be shortened. However, a metal-type glow plug can also be used. In the case of a metal-type glow plug, the heat generating coil is housed in a tube made of a heat-resistant alloy, which is excellent in terms of reliability.

  The relay circuit 8 is a circuit that controls whether or not the power supply voltage is supplied to the glow plugs 7a to 7d. For example, four n-channel power MOSFETs (hereinafter referred to simply as power MOSs) are used. ) Q1 to Q4. The glow plugs 7a to 7d are electrically connected to the power source 14 through the power MOSs Q1 to Q4. The power source 14 is, for example, a battery or an alternator.

  The input terminals (gate electrodes) of the power MOSs Q1 to Q4 are electrically connected to the glow controller 10, and the relay circuit 8 is controlled by the glow controller 10 turning on and off the power MOSs Q1 to Q4.

  Each of the sensors 9a to 9d is a part for detecting an actual combustion state in each of the cylinders 4a to 4d, particularly an actual ignition timing (ignition position), and is directly attached to each of the cylinders 4a to 4d.

  As the sensors 9a to 9d, for example, pressure sensors such as knock sensors are used, and are set so that the combustion states of the respective cylinders 4a to 4d can be detected. However, the present invention is not limited to the knock sensor as long as the combustion state of each of the cylinders 4a to 4d can be predicted by attaching one sensor to some representative point of each of the cylinders 4a to 4d.

  The sensors 9a to 9d are electrically connected to the glow controller 10, and vibrations generated when the engine 1 is started are converted into electric signals by the piezoelectric elements in the sensors 9a to 9d and transmitted to the glow controller 10. It is like that.

  The glow controller 10 is a control unit that controls the heating of the combustion chamber by the glow plugs 7a to 7d, and includes information S1 on the engine speed, information S2 on the fuel injection amount, environmental correction terms (cooling water temperature, atmospheric pressure, temperature, etc.). ), Information S4 such as cylinder discrimination information, cam angle signal, crank signal, and the like.

  The glow controller 10 includes an actually measured ignition timing (combustion state) detected by the sensors 9a to 9d for each of the cylinders 4a to 4d, and a target ignition timing that is preset so as to be optimal in terms of exhaust gas performance for each of the cylinders 4a to 4d. The energization amount (including zero) to each of the glow plugs 7a to 7d is controlled for each cylinder 4a to 4d according to the difference between the cylinders 4a to 4d.

  The glow controller 10 has a PWM (Pulse Width Modulation) circuit, and can output a PWM control signal to each of the glow plugs 7a to 7d. In the PWM control method, the period is constant, the duty cycle of the pulse width (ratio of high (H) to low (L) of the pulse width) is changed according to the magnitude of the input signal, and the passing time is changed. This is a method for variably controlling the average output. The duty ratio is the ratio between the period and the pulse width when a periodic pulse wave is output. When the duty ratio is D, the pulse width is τ, and the period is T, D = τ / T.

  That is, the glow controller 10 determines the actual ignition timing of the cylinders 4a to 4d and the target ignition timing of the cylinders 4a to 4d so that actual ignition occurs when the cylinders 4a to 4d are optimal in terms of exhaust gas performance. The energization amount to each glow plug 7a-7d is controlled by changing the duty ratio of the control pulse signal energized to each glow plug 7a-7d according to the difference. Thereby, since the combustion state of each cylinder 4a-4d can be made into a better state on exhaust gas performance, the exhaust gas performance of the engine 1 can be improved.

The target ignition timing can be automatically created by the glow controller 10 using map data with variables of the engine speed , the fuel injection amount, and the information S1 to S3 of the environmental correction term. Thereby, it can respond to the fluctuation | variation of the target ignition position by a driving | running condition, an environmental condition, etc. That is, since the setting accuracy of the target ignition timing can be improved, the energization control of each of the glow plugs 7a to 7d can be performed more appropriately. As a result, the combustion state of each of the cylinders 4a to 4d can be further improved in terms of exhaust gas performance, so that the exhaust gas performance of the engine 1 can be further improved. The map data is stored in a ROM (Read Only Memory) of the controller 10.

  Next, a glow plug control method for the engine 1 of the present embodiment will be described with reference to FIGS.

  In the glow plug control method for the engine 1 according to the present embodiment, at the time of starting the engine 1 (particularly when it is cold), the target ignition timing is preset for each of the cylinders 4a to 4d so as to be optimal in terms of exhaust gas performance. The energization amount (including zero) to each of the glow plugs 7a to 7d is controlled for each cylinder 4a to 4d so that the actual ignition in the cylinders 4a to 4d is performed. That is, the energization to each of the glow plugs 7a to 7d is made according to the difference between the actually measured ignition timing (measured ignition position) detected for each of the cylinders 4a to 4d and the target ignition timing (target ignition position) for each of the cylinders 4a to 4d. The amount is controlled for each of the cylinders 4a to 4d. Thereby, since the combustion state of each cylinder 4a-4d can be made into a better state on exhaust gas performance, the exhaust gas performance of the engine 1 can be improved. Specifically, for example, the following is performed.

  First, in step 100 of FIG. 2, the target ignition timing is determined for each of the cylinders 4a to 4d. The target ignition timing may be determined in advance by experiments, but is preferably set according to vehicle operating conditions (speed, load, etc.) and environmental conditions (cooling water temperature, atmospheric pressure, temperature, etc.). This is because, as shown in FIG. 3, the target ignition timing PA may vary depending on operating conditions, environmental conditions, etc., as indicated by the target ignition timings PA1 and PA2. This is because the relationship between the target ignition timing PA and the actual ignition timing will also change if the operating conditions and environmental conditions change.

  Therefore, in the glow plug control method according to the present embodiment, each cylinder 4a is input using map data, which is input to the glow controller 10, using information S1 to S3 of the engine speed, fuel injection amount, and environment correction term as variables. Data of the target ignition timing PA of ˜4d is automatically created.

  Thereby, since the target ignition timing of each cylinder 4a-4d can be set according to driving | running conditions, environmental conditions, etc., the setting precision of target ignition timing can be improved. For this reason, the energization control of each of the glow plugs 7a to 7d can be performed more appropriately, and the combustion state of each of the cylinders 4a to 4d can be further improved in terms of the exhaust gas performance. It can be further improved.

  Subsequently, in step 101 of FIG. 2, the difference between the target ignition timing of each cylinder 4a-4d and the actual ignition timing (actual ignition timing) of each cylinder 4a-4d detected by each sensor 9a-9d is obtained. .

  FIG. 4 shows an example of signal waveforms detected by the sensors 9a to 9d. In the cylinder 4a, the difference E1 between the measured ignition timing PR and the target ignition timing PA (broken line) is large. In the cylinder 4b, the measured ignition timing PR and the target ignition timing PA are the same. In the cylinder 4c, the difference E2 between the measured ignition timing PR and the target ignition timing PA is smaller than the difference E1 between the cylinders 4a, and the measured ignition timing PR is close to the target ignition timing PA. In the cylinder 4d, the difference E3 between the measured ignition timing PR and the target ignition timing PA is the largest, and the measured ignition timing PR is far behind the target ignition timing PA.

  Subsequently, in step 102 of FIG. 2, the difference between the target ignition timing PA and the actual ignition timing PR of each of the cylinders 4a to 4d obtained in step 101 (the delay amount of the actual ignition timing PR with respect to the target ignition timing PA). Accordingly, the duty ratio, which is the control value of the PWM circuit of the glow controller 10, is determined for each of the glow plugs 7a to 7d of the cylinders 4a to 4d.

  Subsequently, a control signal set to a desired duty ratio is transmitted for each of the glow plugs 7a to 7d of the cylinders 4a to 4d. Reference numerals CS1 to CS4 in FIG. 1 indicate examples of the control signals.

  Here, according to the delay of the measured ignition timing PR with respect to the target ignition timing PA, that is, the difference between the measured ignition timing PR with respect to the target ignition timing PA is larger (the actual ignition is delayed than the target ignition timing). The duty ratio of the control signals CS1, CS3, CS4 (glow current) to the glow plugs 7a, 7c, 7d is increased to raise the glow temperature of each cylinder 4a, 4c, 4d.

  For example, in the cylinder 4d, since the difference between the target ignition timing PA and the measured ignition timing PR is the largest as shown in FIG. 4, the duty ratio of the control signal CS4 to the glow plug 7d of the cylinder 4d is as shown in FIG. The biggest. Further, for example, in the cylinder 4c, the difference between the target ignition timing PA and the actually measured ignition timing PR is smaller than that of the cylinders 4a and 4d as shown in FIG. 4, so that the glow plug 7c of the cylinder 4c is shown in FIG. The duty ratio of the control signal CS3 is smaller than the duty ratio of the control signals CS1 and CS4 to the glow plugs 7a and 7d of the cylinders 4a and 4c.

  On the other hand, when the mounting ignition timing PR is not delayed with respect to the target ignition timing PA, that is, when there is no difference between the target ignition timing PA and the mounting ignition timing PR (the actual ignition is delayed from the target ignition timing. In the case of combustion at an appropriate ignition timing) or negative (the ignition timing is advanced), the duty ratio of the control signal CS2 to the glow plug 7b is set to zero, and the glow plug 7b Don't let glow current flow through.

  As described above, in the glow plug control method of the present embodiment, the target ignition is performed by increasing the energization amount to the glow plugs 7a, 7c, and 7d so that combustion is likely to occur in the cylinders 4a, 4c, and 4d that are slow in combustion. Combustion can occur at the time. FIG. 5 shows signal waveforms detected by the sensors 9a to 9d of the cylinders 4a to 4d when the glow plug control method of the present embodiment is performed. It can be seen that actual ignition combustion occurs in the vicinity of the target ignition timing PA in each of the cylinders 4a to 4d. Therefore, the combustion state of each of the cylinders 4a to 4d can be made better in terms of exhaust gas performance, so that the exhaust gas performance of the engine 1 can be improved. FIG. 6 shows the exhaust gas performance when the glow plug control method of the present embodiment is performed. Symbol A indicates the target value of the exhaust gas amount under a certain operating condition. It can be seen that nitrogen oxide (NOx), hydrocarbon (HC), and carbon monoxide (CO) all achieve the target. For comparison, FIGS. 9 and 10 show a case where no glow current flows, and FIGS. 11 and 12 show a case of conventional glow control.

  FIG. 9 shows signal waveforms detected by the sensors 9a to 9d of the respective cylinders 4a to 4d when the glow control itself is not performed, and FIG. 10 shows the exhaust gas performance in the case of FIG. In this case, as shown in FIG. 9, misfiring has occurred in the cylinders 4 a and 4 d, so that the exhaust gas amounts of HC and CO exceed the target value A as shown in FIG. 10.

  FIG. 11 shows signal waveforms detected by the sensors 9a to 9d of the cylinders 4a to 4d in the case of conventional glow control, and FIG. 12 shows the exhaust gas performance in the case of FIG. In this case, as shown in FIG. 11, since pre-ignition occurs in the cylinders 4b and 4c, the NOx exhaust gas amount exceeds the target value A as shown in FIG.

  Further, in the glow plug control method of the present embodiment, the power consumption can be reduced by reducing the energization amount (including zero) to the glow plug 7b of the cylinder 4b in which combustion is active. FIG. 7 is a graph showing a comparison of power consumption when the glow plug control method of the present embodiment is used (right: with control) and when it is not used (left: without control). When the glow plug control method according to the present embodiment is used, the power consumption can be reduced by the rest Pb of the cylinder 4b and the energy saving Pac of the cylinders 4a and 4c, compared to the case without control.

  The glow plug control method for an internal combustion engine and the internal combustion engine according to the present invention allow the glow ignition so that actual ignition is performed at the target ignition timing of each of the plurality of cylinders of the internal combustion engine when the internal combustion engine is started (particularly during cold). By controlling the energization amount to the plug for each cylinder, the combustion state of each cylinder can be made better in terms of exhaust gas performance, and the exhaust gas performance of the internal combustion engine can be improved. The present invention can be used for a glow plug control method and an internal combustion engine.

1 Diesel engine (internal combustion engine)
2 Engine block (engine body)
3 Glow plug control devices 4a to 4d Cylinder 5 Intake manifold 6 Exhaust manifolds 7a to 7d Glow plug 8 Relay circuits 9a to 9d Sensor (detection means)
10 Glow controller (control unit)
14 Power supply PA, PA1, PA2 Target ignition timing PR Actual ignition timing CS1-CS4 Control signal

Claims (5)

In a glow plug control method for an internal combustion engine that assists ignition by applying heat to a glow plug provided in each of a plurality of cylinders when starting the internal combustion engine to apply heat to the combustion region of each cylinder,
Glow plug control method for an internal combustion engine for controlling the energization amount to the glow plug for each cylinder so that actual ignition is performed at a target ignition timing set in advance so as to be optimal in terms of exhaust gas performance for each cylinder .   The glow plug of the internal combustion engine according to claim 1, wherein an energization amount to the glow plug is controlled for each cylinder according to a difference between the actually measured ignition timing detected for each cylinder and the target ignition timing for each cylinder. Control method. Increase the glow plug temperature by increasing the duty ratio of the glow current to the glow plug according to the delay of the measured ignition timing relative to the target ignition timing,
The internal combustion engine according to claim 2, wherein when the mounting ignition timing is not delayed with respect to the target ignition timing, the duty ratio of the current flowing through the glow plug is set to zero, and control is performed so that no current flows through the glow plug. Glow plug control method.   The glow plug control method for an internal combustion engine according to any one of claims 1 to 3, wherein the target ignition timing is created using map data in which an engine speed, a fuel injection amount, and an environmental correction term are variables. In an internal combustion engine comprising a glow plug control device that assists ignition by applying heat to a glow plug provided in each of a plurality of cylinders when starting the internal combustion engine to apply heat to the combustion region of each cylinder.
A detection means for detecting an actual ignition timing for each cylinder is provided, and an actual ignition timing detected for each cylinder by the detection means and a target set in advance so as to be optimal in terms of exhaust gas performance for each cylinder. An internal combustion engine comprising a control unit that controls the amount of current supplied to the glow plug for each of the cylinders according to a difference from an ignition timing.

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