JP4396551B2 - Control device for spark ignition internal combustion engine - Google Patents

Description

  The present invention relates to a spark ignition type internal combustion engine represented by an automobile gasoline engine, and more particularly to a control device suitable for an internal combustion engine equipped with a turbocharger.

In a spark ignition internal combustion engine represented by an automobile gasoline engine, the fuel injection amount is increased on the high load side in order to avoid knocking. It is known to increase the fuel injection amount in order to avoid an excessive increase in exhaust temperature (hereinafter referred to as “exhaust temperature” as appropriate) (see Patent Document 1).
Japanese Patent Laid-Open No. 11-36906

  However, if such fuel increase is performed, problems such as a decrease in exhaust performance and fuel consumption performance naturally occur. In particular, in an internal combustion engine equipped with a turbocharger, the exhaust temperature tends to rise in a high rotation range, and there is a tendency that the engine operating range in which the amount of fuel is increased in order to suppress the exhaust temperature rise is expanded. It was.

  The present invention has been made in view of such a problem, and while suppressing an excessive increase in the exhaust temperature, the engine operating range in which the fuel is increased to suppress the exhaust temperature is reduced, thereby reducing the fuel consumption performance and the exhaust gas. The main object of the present invention is to provide a novel spark ignition type internal combustion engine control device capable of effectively improving the performance.

In a control device for a spark ignition internal combustion engine having an ignition device for spark ignition of an air-fuel mixture in a combustion chamber, the engine operating range including the engine speed and the engine load is higher than the first engine operating range including idle. In the second engine operating range, the ignition timing is advanced from the optimal ignition timing at which the engine output becomes the highest, while the exhaust temperature is lowered in the fourth engine operating range higher than the second engine operating range. In order to increase the amount of fuel .

  In the second engine operating range, the ignition timing is advanced from the optimal ignition timing, so that the increase in the exhaust temperature can be suppressed. Therefore, the increase in the fuel injection amount for suppressing the excessive increase in the exhaust temperature is reduced. It can be suppressed or avoided, and fuel efficiency performance and output performance can be improved accordingly.

  For example, in an internal combustion engine equipped with a turbocharger, the exhaust temperature may rise excessively on the high rotation side even in an operation region where the load is relatively low. Such an operation region is set as the second engine operation region. By performing the above-described advance angle control of the ignition timing, it is possible to effectively suppress an increase in fuel for reducing the exhaust temperature.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows a configuration of a gasoline engine with a turbocharger as an embodiment of an internal combustion engine according to the present invention. A plurality of cylinders 2 are arranged in series on the cylinder block 1, and pistons 3 are slidably fitted in the cylinders 2. The cylinder head 4 covering the top of the cylinder 2 is formed with an intake port 6 that is opened and closed by an intake valve 5 and an exhaust port 8 that is opened and closed by an exhaust valve 7. A turbocharger 9, specifically a compressor 9a, is interposed upstream of the intake passage connected to the intake port 6. An exhaust turbine 9 b that drives the compressor 9 a is interposed in an exhaust passage downstream of the exhaust port 8. Further, the outlet side and the inlet side of the exhaust turbine 9 b are connected by an exhaust bypass passage 10, and an electronically controlled waste gate valve 11 is interposed in the passage 10. Further, a supercharging pressure sensor 12 for detecting a supercharging pressure is disposed on the outlet side of the compressor 9a, that is, on the upstream side of the intake port 6.

  The waste gate valve 11 is opened on the engine high speed side so as to keep the supercharging pressure at a predetermined characteristic, and is controlled by the control unit 13. The control unit 13 includes an engine speed by the speed sensor 15, an engine (request) load by the accelerator opening sensor 18, that is, an engine torque, a cooling water temperature by the water temperature sensor 16, a lubricating oil pressure by the hydraulic sensor 17, and the supercharging pressure. A detection signal such as a supercharging pressure by the sensor 12 is input. Then, the control unit 13 outputs a control signal to the above-described waste gate valve 11 based on various detection signals representing these engine operating states, and controls the supercharging pressure to a characteristic according to the engine operating conditions. The control signal is output to the fuel injection valve 19 and the spark plug 20 to control the fuel injection timing, the fuel injection amount, the ignition timing, and the like. As is well known, the spark plug 20 as an ignition device is disposed in the combustion chamber 2A of the cylinder 2 and sparks the mixture in the combustion chamber 2A.

  The cylinder block 1 is provided with a knocking sensor 14 for detecting knocking vibration of a predetermined frequency, and the knocking detection signal is input to the control unit 13. For example, an in-cylinder pressure sensor may be provided in the washer portion of the spark plug 20 to detect knocking based on a change in the in-cylinder pressure. The control unit 13 variably controls the ignition timing by the ignition plug 20 based on the detection of the knocking.

  Next, with reference to FIG. 2 and FIG. 3, characteristic control contents of the present embodiment will be described. As shown in FIG. 2, in this embodiment, the engine operating range determined by the engine speed and the engine load (torque) is roughly classified into four regions R1 to R4. In the first engine operating range R1 on the low rotation / low load side that is the engine normal range including the idle and partial load range, the fuel injection amount and the intake air amount are controlled so as to maintain the theoretical air-fuel ratio, and the ignition timing is It is set at the MBT point (see FIG. 3), which is the optimum ignition timing at which the engine output becomes the highest.

  By the way, generally, the ignition timing is the optimum ignition timing at which the engine output becomes the highest, that is, the MBT point, or the trace knock point on the retard side from the MBT point. As disclosed in Patent Document 1 above, in a situation where the ignition timing is controlled to the trace knock point based on the output of the knocking sensor 14, the ignition timing is advanced as far as possible toward the MBT point. When knocking at a predetermined level is detected, the occurrence of knocking can be suppressed with good responsiveness by retarding the ignition timing to the predetermined level.

  On the other hand, in the present embodiment, in the second engine operating range R2 on the higher load side than the first engine operating range R1, the ignition timing is set to the over-advanced angle point P1 that is further advanced than the MBT point. is doing. That is, the ignition timing is advanced from the MBT point only in the predetermined second engine operating range R2. As shown in FIG. 3, at the over-advanced angle point P1, the engine output (torque) is reduced compared to the MBT point, but the exhaust temperature can be reduced. Therefore, in the second engine operating region R2, by excessively increasing the ignition timing, it is possible to suppress an excessive increase in the exhaust gas temperature and to avoid or reduce the fuel increase. Fuel efficiency and exhaust performance can be improved. That is, by making the ignition timing over-advance, it is possible to substantially reduce the operating range where the fuel increase should be performed and to expand the operating range at the stoichiometric air-fuel ratio.

  In the third engine operating region R3 on the high load side including the fully open region, knocking is likely to occur. Therefore, in order to suppress and avoid the occurrence of knocking, the fuel injection amount necessary to maintain the stoichiometric air-fuel ratio. More than the amount. That is, a rich operation in which the fuel is richer than the stoichiometric air-fuel ratio is performed. Further, in the fourth engine operating region R4 on the higher rotation side than the second engine operating region R2 and on the lower load side than the third engine operating region R3, the exhaust temperature is sufficiently increased only by the above-described advance angle. In order to prevent knocking by retarding the ignition timing, basically, the ignition timing is not excessively advanced, that is, the ignition timing is set to the MBT point. It is set thereafter and the increase in the exhaust gas temperature is suppressed by increasing the fuel injection amount.

  FIG. 2 shows a road load (load load: load necessary to drive the vehicle without acceleration / deceleration on a flat road surface) line L1 and a general (over-advance angle control of ignition timing on the road load line L1). (Not performed) A setting example T1 and a setting example T2 including the over-advance angle control of this embodiment are shown. As shown in the figure, according to the present embodiment, the fuel injection amount is obtained by over-igniting the ignition timing instead of the fuel increase amount from the point A to the point B which is the second engine operating range R2. Without increasing the amount of fuel, that is, without performing rich operation, the exhaust temperature can be suppressed, and fuel efficiency and exhaust performance can be improved by the amount that fuel is not increased. When the engine speed and the engine load further increase from the point B and shift to the third engine operating range R3, the amount of fuel is increased in order to suppress and avoid the occurrence of knocking.

  Further, in the case of moving from point B to point C, that is, when shifting from the second engine operating range R2 to the third engine operating range R3 (or the fourth engine operating range R4), the operation is caused by a sudden change in the ignition timing. In order to prevent the deterioration of the engine performance, control is performed in which the fuel increase is gradually increased while gradually decreasing the degree of over-advanced ignition timing. That is, among the third engine operating range R3 and the fourth engine operating range R4, in the region close to the second engine operating range R2 (for example, the operating range between point B and point C), the second engine operating range R2 The ignition timing can be smoothly changed by increasing the degree of over-advanced angle as it approaches. When such control is applied, it is possible to suppress the fuel increase amount by over-advancing in the region in the vicinity of the second engine operating region R2, that is, in the range ΔD from the point A to the point C, Exhaust performance can be improved.

  However, when the ignition timing is over-advanced as described above, as shown in FIG. 3, the engine output torque is reduced while the above-described remarkable effects of exhaust and fuel efficiency are obtained. Therefore, preferably, the fuel consumption mode M1 in which the over-advance angle is performed and the normal mode M2 in which the over-advance angle is not performed can be switched by a changeover switch 21 (see FIG. 1) that can be operated by the driver. .

  An example of the control routine is shown in FIG. When the changeover switch 21 is set to the fuel efficiency mode M1, the process proceeds from step (simply indicated as “S” in the figure) 1 to step 2, and the ignition timing is over-advanced in the second engine operating range R2 in FIG. At the same time, a control map of preset ignition timing and fuel injection amount is selected so as to avoid or suppress the fuel increase. On the other hand, when the changeover switch 21 is set to the normal mode M2, the process proceeds from step 1 to step 3 and is set in advance so as to increase the fuel without performing the advance timing of the ignition timing in the second engine operating range R2. A control map of the ignition timing and the fuel injection amount is selected. The control map in the normal mode M2 is different from the control map in the fuel efficiency mode M1, and is set in advance and stored in a storage medium such as a memory. In step 5, based on the engine operating state such as the engine speed and engine load (torque) read in step 4, the control timing selected in step 2 or 3 is referred to, and the ignition timing and fuel injection amount ( Or the amount of increase). By using the changeover switch 21 as described above, it is possible to properly use the fuel consumption mode M1 in which the overtravel angle is performed and the normal mode M2 in which the overtravel angle is not performed, according to the driver's request.

  The characteristic technical ideas of the present invention that can be understood from the above description are listed. However, the present invention is not limited to the configuration of the embodiment given the reference numerals, and includes various modifications and changes without departing from the spirit thereof.

  (1) In a control device for a spark ignition type internal combustion engine having an ignition device (ignition plug) 20 for spark ignition of an air-fuel mixture in the combustion chamber 2A, the engine operating range including the engine speed and the engine load includes an idle. In the second engine operating range R2 on the higher rotation side than the one engine operating range R1, the ignition timing is advanced from the optimum ignition timing (MBT point) at which the engine output becomes the highest.

  (2) The first engine operating range R1 is, for example, a low rotation / low load side engine normal range including a partial load range, and the ignition timing is set to the optimal ignition timing (MBT point).

  (3) The third engine operation region R3 is a region on the high load side including full opening, and preferably increases the fuel injection amount in order to avoid knocking. The second engine operating range R2 is an operating range on a lower load side than the third engine operating range R3.

  (4) More preferably, the exhaust gas temperature is lowered in the fourth engine operating region R4 on the higher rotation side than the second engine operating region R2 and on the lower load side than the third engine operating region R3. Increase the amount of fuel.

  (5) More preferably, the fuel consumption mode M1 in which the ignition timing is advanced from the optimal ignition timing MBT in the second engine operating range R2, and the ignition timing is matched or delayed with the optimal ignition timing in the second engine operating range R2. There is a switching means (switch 21) that can switch between the normal mode M2 for turning corners.

  (6) In particular, in an internal combustion engine equipped with the turbocharger 9, the exhaust temperature tends to rise excessively on the high rotation side, so the control of the present invention is extremely effective.

BRIEF DESCRIPTION OF THE DRAWINGS The system figure which shows simply the structure of the spark ignition type internal combustion engine to which the control apparatus of one Example of this invention is applied. Explanatory drawing for demonstrating the control content which concerns on a present Example. Explanatory drawing which shows the relationship between ignition timing and engine output torque. The flowchart which shows the flow of the switching control of the operation mode which concerns on a present Example.

Explanation of symbols

2A ... Combustion chamber 9 ... Turbocharger 20 ... Spark plug (ignition device)

Claims (6)

In a control device for a spark ignition internal combustion engine having an ignition device for spark ignition of an air-fuel mixture in a combustion chamber,
In the second engine operating range where the engine operating range including the engine speed and the engine load is higher than the first engine operating range including idle, the ignition timing is advanced from the optimum ignition timing at which the engine output is highest. On the other hand, a control device for a spark ignition type internal combustion engine, characterized in that fuel is increased in order to lower the exhaust temperature in a fourth engine operating region at a higher speed than the second engine operating region .   2. The spark ignition type internal combustion engine control device according to claim 1, wherein the ignition timing is set to the optimum ignition timing in the first engine operating range. In the third engine operating range, increase the fuel injection amount to avoid knocking,
The control apparatus for a spark ignition type internal combustion engine according to claim 1 or 2, wherein the second engine operating range is on a lower load side than the third engine operating range. Switching that can be switched between a fuel efficiency mode in which the ignition timing is advanced from the optimal ignition timing in the second engine operating range and a normal mode in which the ignition timing is matched or retarded to the optimal ignition timing in the second engine operating range control apparatus for a spark ignition type internal combustion engine according to claim 1, characterized in that the perforated means. The control device for a spark ignition type internal combustion engine according to any one of claims 1 to 4, further comprising a turbocharger . When the operating point shifts from the second engine operating range to the third engine operating range or the fourth engine operating range, the fuel increase is gradually increased while gradually decreasing the degree of advance of the ignition timing. control apparatus for a spark ignition type internal combustion engine according to claim 3, characterized in that to perform.

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